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Shelley JR, McHugh BJ, Wills J, Dorin JR, Weller R, Clarke DJ, Davidson DJ. A mechanistic evaluation of human beta defensin 2 mediated protection of human skin barrier in vitro. Sci Rep 2023; 13:2271. [PMID: 36755116 PMCID: PMC9908873 DOI: 10.1038/s41598-023-29558-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/06/2023] [Indexed: 02/10/2023] Open
Abstract
The human skin barrier, a biological imperative, is impaired in inflammatory skin diseases such as atopic dermatitis (AD). Staphylococcus aureus is associated with AD lesions and contributes to pathological inflammation and further barrier impairment. S. aureus secretes extracellular proteases, such as V8 (or 'SspA'), which cleave extracellular proteins to reduce skin barrier. Previous studies demonstrated that the host defence peptide human beta-defensin 2 (HBD2) prevented V8-mediated damage. Here, the mechanism of HBD2-mediated barrier protection in vitro is examined. Application of exogenous HBD2 provided protection against V8, irrespective of timeline of application or native peptide folding, raising the prospect of simple peptide analogues as therapeutics. HBD2 treatment, in context of V8-mediated damage, modulated the proteomic/secretomic profiles of HaCaT cells, altering levels of specific extracellular matrix proteins, potentially recovering V8 damage. However, HBD2 alone did not substantially modulate cellular proteomic/secretomics profiles in the absence of damage, suggesting possible therapeutic targeting of lesion damage sites only. HBD2 did not show any direct protease inhibition or induce expression of known antiproteases, did not alter keratinocyte migration or proliferation, or form protective nanonet structures. These data validate the barrier-protective properties of HBD2 in vitro and establish key protein datasets for further targeted mechanistic analyses.
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Affiliation(s)
- Jennifer R Shelley
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, BioQuarter, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, Scotland, UK.
- The Commonwealth Building, The Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - Brian J McHugh
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, BioQuarter, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, Scotland, UK
| | - Jimi Wills
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Cancer, The University of Edinburgh, Western General Hospital Campus, Crewe Road, Edinburgh, EH4 2XU, Scotland, UK
| | - Julia R Dorin
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, BioQuarter, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, Scotland, UK
| | - Richard Weller
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, BioQuarter, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, Scotland, UK
| | - David J Clarke
- The EastChem School of Chemistry, University of Edinburgh, Joseph Black Building, Brewster Road, Edinburgh, EH9 3FJ, UK
| | - Donald J Davidson
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, BioQuarter, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, Scotland, UK
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Dorin JR, Porteous DJ. Role of animal models in gene therapy. Gene Ther 2020. [DOI: 10.1201/9781003076919-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Defensins are short, rapidly evolving, cationic antimicrobial host defence peptides with a repertoire of functions, still incompletely realised, that extends beyond direct microbial killing. They are released or secreted at epithelial surfaces, and in some cases, from immune cells in response to infection and inflammation. Defensins have been described as endogenous alarmins, alerting the body to danger and responding to inflammatory signals by promoting both local innate and adaptive systemic immune responses. However, there is now increasing evidence that they exert variable control on the response to danger; creating a dichotomous response that can suppress inflammation in some circumstances but exacerbate the response to danger and damage in others and, at higher levels, lead to a cytotoxic effect. Focussing in this review on human β-defensins, we discuss the evidence for their functions as proinflammatory, immune activators amplifying the response to infection or damage signals and/or as mediators of resolution of damage, contributing to a return to homeostasis. Finally, we consider their involvement in the development of autoimmune diseases.
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Affiliation(s)
- Jennifer R Shelley
- Centre for Inflammation Research, The University of Edinburgh, Edinburgh BioQuarter, Edinburgh, Scotland
| | - Donald J Davidson
- Centre for Inflammation Research, The University of Edinburgh, Edinburgh BioQuarter, Edinburgh, Scotland
| | - Julia R Dorin
- Centre for Inflammation Research, The University of Edinburgh, Edinburgh BioQuarter, Edinburgh, Scotland
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Boeckel SRV, Hrabalkova L, Baker TL, MacPherson H, Frew L, Boyle AK, McHugh BJ, Wilson K, Norman JE, Dorin JR, Davidson DJ, Stock SJ. Cathelicidins and the Onset of Labour. Sci Rep 2019; 9:7356. [PMID: 31089176 PMCID: PMC6517412 DOI: 10.1038/s41598-019-43766-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 05/01/2019] [Indexed: 01/07/2023] Open
Abstract
Preterm birth, defined as delivery before 37 weeks of gestation, is the leading cause of neonatal mortality and morbidity. Infection and inflammation are frequent antecedents of spontaneous preterm birth. Cathelicidin, an antimicrobial host defence peptide, is induced by infection and inflammation and although expressed in the reproductive tract and fetal tissues, its role in the pathogenesis of spontaneous preterm birth is unknown. Here we demonstrate that cathelicidin expression is increased at RNA and protein level in the mouse uterus in a model of inflammation-induced labour, where ultrasound guided intrauterine injection of lipopolysaccharide (LPS) at E17 stimulates preterm delivery within 24 hours. Cathelicidin-deficient (Camp−/−) mice are less susceptible to preterm delivery than wild type mice following intrauterine injection of 1 μg of LPS, and this is accompanied by a decrease in circulating IL-6, an inflammatory mediator implicated in the onset of labour. We also show that the proportion of cathelicidin expressing cells in the myometrium is higher in samples obtained from women in labour at term than pre-labour. Together, these data suggest that cathelicidin has roles in mediating pro-inflammatory responses in a murine model of inflammation-induced labour, and in human term labour.
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Affiliation(s)
- Sara R van Boeckel
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Lenka Hrabalkova
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Tina L Baker
- University of Edinburgh Centre for Inflammation Research, QMRI, Edinburgh, United Kingdom
| | - Heather MacPherson
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Lorraine Frew
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Ashley K Boyle
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Brian J McHugh
- University of Edinburgh Centre for Inflammation Research, QMRI, Edinburgh, United Kingdom
| | - Kirsten Wilson
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Jane E Norman
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom
| | - Julia R Dorin
- University of Edinburgh Centre for Inflammation Research, QMRI, Edinburgh, United Kingdom
| | - Donald J Davidson
- University of Edinburgh Centre for Inflammation Research, QMRI, Edinburgh, United Kingdom
| | - Sarah J Stock
- Tommy's Centre for Maternal and Fetal Health at the MRC Centre for Reproductive Health, University of Edinburgh, QMRI, Edinburgh, United Kingdom.
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McHugh BJ, Wang R, Li HN, Beaumont PE, Kells R, Stevens H, Young L, Rossi AG, Gray RD, Dorin JR, Gwyer Findlay EL, Brough D, Davidson DJ. Cathelicidin is a "fire alarm", generating protective NLRP3-dependent airway epithelial cell inflammatory responses during infection with Pseudomonas aeruginosa. PLoS Pathog 2019; 15:e1007694. [PMID: 30978238 PMCID: PMC6481867 DOI: 10.1371/journal.ppat.1007694] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 04/24/2019] [Accepted: 03/11/2019] [Indexed: 01/23/2023] Open
Abstract
Pulmonary infections are a major global cause of morbidity, exacerbated by an increasing threat from antibiotic-resistant pathogens. In this context, therapeutic interventions aimed at protectively modulating host responses, to enhance defence against infection, take on ever greater significance. Pseudomonas aeruginosa is an important multidrug-resistant, opportunistic respiratory pathogen, the clearance of which can be enhanced in vivo by the innate immune modulatory properties of antimicrobial host defence peptides from the cathelicidin family, including human LL-37. Initially described primarily as bactericidal agents, cathelicidins are now recognised as multifunctional antimicrobial immunomodulators, modifying host responses to pathogens, but the key mechanisms involved in these protective functions are not yet defined. We demonstrate that P. aeruginosa infection of airway epithelial cells promotes extensive infected cell internalisation of LL-37, in a manner that is dependent upon epithelial cell interaction with live bacteria, but does not require bacterial Type 3 Secretion System (T3SS). Internalised LL-37 acts as a second signal to induce inflammasome activation in airway epithelial cells, which, in contrast to myeloid cells, are relatively unresponsive to P. aeruginosa. We demonstrate that this is mechanistically dependent upon cathepsin B release, and NLRP3-dependent activation of caspase 1. These result in LL-37-mediated release of IL-1β and IL-18 in a manner that is synergistic with P. aeruginosa infection, and can induce caspase 1-dependent death of infected epithelial cells, and promote neutrophil chemotaxis. We propose that cathelicidin can therefore act as a second signal, required by P. aeruginosa infected epithelial cells to promote an inflammasome-mediated altruistic cell death of infection-compromised epithelial cells and act as a "fire alarm" to enhance rapid escalation of protective inflammatory responses to an uncontrolled infection. Understanding this novel modulatory role for cathelicidins, has the potential to inform development of novel therapeutic strategies to antibiotic-resistant pathogens, harnessing innate immunity as a complementation or alternative to current interventions.
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Affiliation(s)
- Brian J. McHugh
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Rongling Wang
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Hsin-Ni Li
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Paula E. Beaumont
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Rebekah Kells
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Holly Stevens
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Lisa Young
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Adriano G. Rossi
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Robert D. Gray
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Julia R. Dorin
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - Emily L. Gwyer Findlay
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
| | - David Brough
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Donald J. Davidson
- Centre for Inflammation Research at the University of Edinburgh, Queens’ Medical Research Institute, Edinburgh BioQuarter, Little France Crescent, Edinburgh, United Kingdom
- * E-mail:
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Sun CQ, Arnold RS, Hsieh CL, Dorin JR, Lian F, Li Z, Petros JA. Discovery and mechanisms of host defense to oncogenesis: targeting the β-defensin-1 peptide as a natural tumor inhibitor. Cancer Biol Ther 2019; 20:774-786. [PMID: 30900935 PMCID: PMC6605992 DOI: 10.1080/15384047.2018.1564564] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 11/27/2018] [Accepted: 12/25/2018] [Indexed: 12/28/2022] Open
Abstract
Human beta-defensin-1 (hBD-1) is one of a number of small cationic host-defense peptides. Besides its well-known broad-spectrum antimicrobial function, hBD-1 has recently been identified as a chromosome 8p tumor-suppressor gene. The role of hBD-1 in modulating the host immune response to oncogenesis, associated with cell signaling and potential therapeutic applications, has become increasingly appreciated over time. In this study, multiple approaches were used to illustrate hBD-1 anti-tumor activities. Results demonstrate that hBD-1 peptide alters human epidermal growth factor receptor 2 (HER2) signal transduction and represses retroviral-mediated transgene expression in cancer cells. Loss of orthologous murine defense-1 (mBD1) in mice enhances nickel sulfate-induced leiomyosarcoma and causes mouse kidney cells to exhibit increased susceptibility to HPV-16 E6/7-induced neoplastic transformation. Furthermore, for the first time, a novel function of the urine-derived hBD-1 peptide was discovered to suppress bladder cancer growth and this may lead to future applications in the treatment of malignancy.
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Affiliation(s)
- Carrie Q. Sun
- Department of Urology and Winship Cancer Institute, Emory University, Atlanta, Georgia
| | - Rebecca S. Arnold
- Department of Urology and Winship Cancer Institute, Emory University, Atlanta, Georgia
| | - Chia-Ling Hsieh
- Department of Molecular Medicine, China Medical University Hospital, Taipei, Taiwan
| | - Julia R. Dorin
- Center for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - Fei Lian
- Emory University School of Medicine, Emory University, Atlanta, Georgia
| | - Zhenghong Li
- School of Medicine, Central South University, Changsha City, Human Province, P. R. China
| | - John A. Petros
- Department of Urology and Winship Cancer Institute, Emory University, Atlanta, Georgia
- Atlanta Veterans Affairs Medical Center, Atlanta, Georgia
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7
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McGlasson SL, Semple F, MacPherson H, Gray M, Davidson DJ, Dorin JR. Human β-defensin 3 increases the TLR9-dependent response to bacterial DNA. Eur J Immunol 2017; 47:658-664. [PMID: 28102569 PMCID: PMC5412915 DOI: 10.1002/eji.201646799] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 12/22/2016] [Accepted: 01/17/2017] [Indexed: 01/20/2023]
Abstract
Human β-defensin 3 (hBD3) is a cationic antimicrobial peptide with potent bactericidal activity in vitro. HBD3 is produced in response to pathogen challenge and can modulate immune responses. The amplified recognition of self-DNA by human plasmacytoid dendritic cells has been previously reported, but we show here that hBD3 preferentially enhances the response to bacterial DNA in mouse Flt-3 induced dendritic cells (FLDCs) and in human peripheral blood mononuclear cells. We show the effect is mediated through TLR9 and although hBD3 significantly increases the cellular uptake of both E. coli and self-DNA in mouse FLDCs, only the response to bacterial DNA is enhanced. Liposome transfection also increases uptake of bacterial DNA and amplifies the TLR9-dependent response. In contrast to hBD3, lipofection of self-DNA enhances inflammatory signaling, but the response is predominantly TLR9-independent. Together, these data show that hBD3 has a role in the innate immune-mediated response to pathogen DNA, increasing inflammatory signaling and promoting activation of the adaptive immune system via antigen presenting cells including dendritic cells. Therefore, our data identify an additional immunomodulatory role for this copy-number variable defensin, of relevance to host defence against infection and indicate a potential for the inclusion of HBD3 in pathogen DNA-based vaccines.
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Affiliation(s)
| | - Fiona Semple
- MRC Human Genetics UnitIGMMUniversity of EdinburghEdinburghUK
| | | | - Mohini Gray
- MRC Centre for Inflammation ResearchQMRIUniversity of EdinburghEdinburghUK
| | - Donald J. Davidson
- MRC Centre for Inflammation ResearchQMRIUniversity of EdinburghEdinburghUK
| | - Julia R. Dorin
- MRC Human Genetics UnitIGMMUniversity of EdinburghEdinburghUK
- MRC Centre for Inflammation ResearchQMRIUniversity of EdinburghEdinburghUK
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Wang B, McHugh BJ, Qureshi A, Campopiano DJ, Clarke DJ, Fitzgerald JR, Dorin JR, Weller R, Davidson DJ. IL-1β-Induced Protection of Keratinocytes against Staphylococcus aureus-Secreted Proteases Is Mediated by Human β-Defensin 2. J Invest Dermatol 2017; 137:95-105. [PMID: 27702565 PMCID: PMC5176011 DOI: 10.1016/j.jid.2016.08.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/12/2016] [Accepted: 08/23/2016] [Indexed: 12/11/2022]
Abstract
Atopic dermatitis (AD) is a common chronic inflammatory skin disease that results in significant morbidity. A hallmark of AD is disruption of the critical barrier function of upper epidermal layers, causatively linked to environmental stimuli, genetics, and infection, and a critical current target for the development of new therapeutic and prophylactic interventions. Staphylococcus aureus is an AD-associated pathogen producing virulence factors that induce skin barrier disruption in vivo and contribute to AD pathogenesis. We show, using immortalized and primary keratinocytes, that S. aureus protease SspA/V8 is the dominant secreted factor (in laboratory and AD clinical strains of S. aureus) inducing barrier integrity impairment and tight junction damage. V8-induced integrity damage was inhibited by an IL-1β-mediated mechanism, independent of effects on claudin-1. Induction of keratinocyte expression of the antimicrobial/host defense peptide human β-defensin 2 (hBD2) was found to be the mechanism underpinning this protective effect. Endogenous hBD2 expression was required and sufficient for protection against V8 protease-mediated integrity damage, and exogenous application of hBD2 was protective. This modulatory property of hBD2, unrelated to antibacterial effects, gives new significance to the defective induction of hBD2 in the barrier-defective skin lesions of AD and indicates therapeutic potential.
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Key Words
- ad, atopic dermatitis
- hbd, human β-defensin
- hdp, host defense peptide
- hpek, human primary epidermal keratinocyte
- lps, lipopolysaccharide
- lta, lipoteichoic acid
- oe, overexpressing
- shrna, small hairpin rna
- ssp, staphylococcus aureus serine protease
- tj, tight junction
- vo, vector only
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Affiliation(s)
- Bingjie Wang
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Brian J McHugh
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Ayub Qureshi
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | | | - David J Clarke
- School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - J Ross Fitzgerald
- The Roslin Institute and Edinburgh Infectious Diseases, University of Edinburgh, Easter Bush, Midlothian, UK
| | - Julia R Dorin
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Richard Weller
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Donald J Davidson
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK.
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Abstract
β-defensin peptides are a large family of antimicrobial peptides. Although they kill microbes in vitro and interact with immune cells, the precise role of these genes in vivo remains uncertain. Despite their inducible presence at mucosal surfaces, their main site of expression is the epididymis. Recent evidence suggests that a major function of these peptides is in sperm maturation. In addition to previous work suggesting this, work at the MRC Human Genetics Unit, Edinburgh, has shown that homozygous deletion of a cluster of nine β-defensin genes in the mouse results in profound male sterility. The spermatozoa derived from the mutants had reduced motility and increased fragility. Epididymal spermatozoa isolated from the cauda region of the homozygous mutants demonstrated precocious capacitation and increased spontaneous acrosome reactions compared with those from wild-types. Despite this, these mutant spermatozoa had reduced ability to bind to the zona pellucida of oocytes. Ultrastructural examination revealed a disintegration of the microtubule structure of mutant-derived spermatozoa isolated from the epididymal cauda region, but not from the caput. Consistent with premature acrosome reaction and hyperactivation, spermatozoa from mutant animals had significantly increased intracellular calcium content. This work demonstrates that in vivo β-defensins are essential for successful sperm maturation, and that their disruption alters intracellular calcium levels, which most likely leads to premature activation and spontaneous acrosome reactions that result in hyperactivation and loss of microtubule structure of the axoneme. Determining which of the nine genes are responsible for the phenotype and the relevance to human sperm function is important for future work on male infertility.
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Affiliation(s)
- Julia R Dorin
- Formerly at MRC Human Genetics Unit, IGMM, University of Edinburgh, now at MRC Centre for Inflammation Research, University of Edinburgh, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, United Kingdom
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10
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Semple F, MacPherson H, Webb S, Kilanowski F, Lettice L, McGlasson SL, Wheeler AP, Chen V, Millhauser GL, Melrose L, Davidson DJ, Dorin JR. Human β-Defensin 3 [corrected] Exacerbates MDA5 but Suppresses TLR3 Responses to the Viral Molecular Pattern Mimic Polyinosinic:Polycytidylic Acid. PLoS Genet 2015; 11:e1005673. [PMID: 26646717 PMCID: PMC4672878 DOI: 10.1371/journal.pgen.1005673] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/26/2015] [Indexed: 11/19/2022] Open
Abstract
Human β-defensin 3 (hBD3) is a cationic host defence peptide and is part of the innate immune response. HBD3 is present on a highly copy number variable block of six β-defensin genes, and increased copy number is associated with the autoimmune disease psoriasis. It is not known how this increase influences disease development, but psoriasis is a T cell-mediated disease and activation of the innate immune system is required for the initial trigger that leads to the amplification stage. We investigated the effect of hBD3 on the response of primary macrophages to various TLR agonists. HBD3 exacerbated the production of type I Interferon-β in response to the viral ligand mimic polyinosinic:polycytidylic acid (polyI:C) in both human and mouse primary cells, although production of the chemokine CXCL10 was suppressed. Compared to polyI:C alone, mice injected with both hBD3 peptide and polyI:C also showed an enhanced increase in Interferon-β. Mice expressing a transgene encoding hBD3 had elevated basal levels of Interferon-β, and challenge with polyI:C further increased this response. HBD3 peptide increased uptake of polyI:C by macrophages, however the cellular response and localisation of polyI:C in cells treated contemporaneously with hBD3 or cationic liposome differed. Immunohistochemistry showed that hBD3 and polyI:C do not co-localise, but in the presence of hBD3 less polyI:C localises to the early endosome. Using bone marrow derived macrophages from knockout mice we demonstrate that hBD3 suppresses the polyI:C-induced TLR3 response mediated by TICAM1 (TRIF), while exacerbating the cytoplasmic response through MDA5 (IFIH1) and MAVS (IPS1/CARDIF). Thus, hBD3, a highly copy number variable gene in human, influences cellular responses to the viral mimic polyI:C implying that copy number may have a significant phenotypic effect on the response to viral infection and development of autoimmunity in humans. Defensins are classically known as antimicrobial peptides due to their ability to rapidly kill pathogens including bacteria, viruses and fungi. They are produced in the presence of infectious agents at body surfaces exposed to the environment. Increasingly, their functional repertoire is expanding, and they have been shown to modulate the immune system. In humans, there is a block of six β-defensin genes that varies in copy number in the population. Individuals with an increased number of β-defensin genes have an increased likelihood of developing the skin autoimmune disease psoriasis. It is not known how this increase in gene copy number influences development of the disease, and psoriasis is a complex interplay of genomic and environmental factors that trigger disease progression and include exposure to viruses. We examined whether a molecular pattern characteristic of viruses produces an altered immune response in the presence of the defensin human β-defensin 3 (hBD3). We find that hBD3 triggers a larger interferon defence response to this viral mimic by increasing accessibility to a cellular receptor that recognises viral patterns. Interferon is known to be important in autoimmunity and our work may explain why individuals with increased β-defensin number are predisposed to develop psoriasis.
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Affiliation(s)
- Fiona Semple
- MRC Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute (QMRI), Edinburgh, United Kingdom
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Heather MacPherson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Sheila Webb
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Fiona Kilanowski
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Laura Lettice
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Sarah L. McGlasson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Ann P. Wheeler
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
| | - Valerie Chen
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Glenn L. Millhauser
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Lauren Melrose
- MRC Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute (QMRI), Edinburgh, United Kingdom
| | - Donald J. Davidson
- MRC Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute (QMRI), Edinburgh, United Kingdom
| | - Julia R. Dorin
- MRC Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute (QMRI), Edinburgh, United Kingdom
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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11
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Abstract
Recent work in humans and mouse has confirmed the involvement of the host defence β-defensin peptides in male fertility. We discuss here the work that has implicated β-defensins in sperm function including the identification of the epididymis as the predominant site of expression of the peptides and the in vivo consequences of mutation and deletion. The potential dual role of these peptides in the regulation of infection and control of sperm maturation is compelling and may combine their antimicrobial activity with the ability of these molecules to interact with cell membrane receptors and modulate ion transport.
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Affiliation(s)
- Julia R Dorin
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Christopher L R Barratt
- Reproductive and Developmental Biology, Medical School, University of Dundee, Ninewells Hospital, Dundee, UK
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12
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Zhou YS, Webb S, Lettice L, Tardif S, Kilanowski F, Tyrrell C, MacPherson H, Semple F, Tennant P, Baker T, Hart A, Devenney P, Perry P, Davey T, Barran P, Barratt CL, Dorin JR. Partial deletion of chromosome 8 β-defensin cluster confers sperm dysfunction and infertility in male mice. PLoS Genet 2013; 9:e1003826. [PMID: 24204287 PMCID: PMC3812073 DOI: 10.1371/journal.pgen.1003826] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/09/2013] [Indexed: 01/06/2023] Open
Abstract
β-defensin peptides are a family of antimicrobial peptides present at mucosal surfaces, with the main site of expression under normal conditions in the male reproductive tract. Although they kill microbes in vitro and interact with immune cells, the precise role of these genes in vivo remains uncertain. We show here that homozygous deletion of a cluster of nine β-defensin genes (DefbΔ9) in the mouse results in male sterility. The sperm derived from the mutants have reduced motility and increased fragility. Epididymal sperm isolated from the cauda should require capacitation to induce the acrosome reaction but sperm from the mutants demonstrate precocious capacitation and increased spontaneous acrosome reaction compared to wild-types but have reduced ability to bind the zona pellucida of oocytes. Ultrastructural examination reveals a defect in microtubule structure of the axoneme with increased disintegration in mutant derived sperm present in the epididymis cauda region, but not in caput region or testes. Consistent with premature acrosome reaction, sperm from mutant animals have significantly increased intracellular calcium content. Thus we demonstrate in vivo that β-defensins are essential for successful sperm maturation, and their disruption leads to alteration in intracellular calcium, inappropriate spontaneous acrosome reaction and profound male infertility. β-defensins are small molecules, considered primarily to be antimicrobials and important in the first defence response to invading organisms. They are predominantly produced at surfaces in contact with the outside environment and these include skin, airway and reproductive tract. We show here that when we delete from the mouse a subset of nine β-defensin genes, surprisingly the main consequence is that the male mice are completely infertile. When normal sperm leave the male and enter the female reproductive tract they are triggered to undergo a reaction that alters the membrane properties of the sperm and allows fertilisation. We show here that sperm isolated from the male mice, that no longer make these β-defensins, are prematurely ready to fertilise an egg. It is far too early for this to happen and as a consequence the sperm are severely reduced in their ability to move and have a major defect in the structure of their tail. We provide evidence that the reason this has happened is due to a dysregulation of calcium transport. This work is important for understanding defensin gene function in a living organism and may enable the design of novel contraceptives with additional antibiotic ability.
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Affiliation(s)
- Yu S. Zhou
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Sheila Webb
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Laura Lettice
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Steve Tardif
- Reproductive and Developmental Biology, Medical School, University of Dundee, Ninewells Hospital, Dundee, Scotland, United Kingdom
| | - Fiona Kilanowski
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Christine Tyrrell
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Heather MacPherson
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Fiona Semple
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Peter Tennant
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Tina Baker
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Alan Hart
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Paul Devenney
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Paul Perry
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Tracey Davey
- EM Research Services, Newcastle Medical School, Newcastle University, Newcastle, England, United Kingdom
| | - Perdita Barran
- School of Chemistry, Joseph Black Building, Edinburgh, Scotland
| | - Chris L. Barratt
- Reproductive and Developmental Biology, Medical School, University of Dundee, Ninewells Hospital, Dundee, Scotland, United Kingdom
| | - Julia R. Dorin
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
- * E-mail:
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13
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Reijns MAM, Rabe B, Rigby RE, Mill P, Astell KR, Lettice LA, Boyle S, Leitch A, Keighren M, Kilanowski F, Devenney PS, Sexton D, Grimes G, Holt IJ, Hill RE, Taylor MS, Lawson KA, Dorin JR, Jackson AP. Enzymatic removal of ribonucleotides from DNA is essential for mammalian genome integrity and development. Cell 2012; 149:1008-22. [PMID: 22579044 PMCID: PMC3383994 DOI: 10.1016/j.cell.2012.04.011] [Citation(s) in RCA: 349] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 02/21/2012] [Accepted: 04/23/2012] [Indexed: 12/01/2022]
Abstract
The presence of ribonucleotides in genomic DNA is undesirable given their increased susceptibility to hydrolysis. Ribonuclease (RNase) H enzymes that recognize and process such embedded ribonucleotides are present in all domains of life. However, in unicellular organisms such as budding yeast, they are not required for viability or even efficient cellular proliferation, while in humans, RNase H2 hypomorphic mutations cause the neuroinflammatory disorder Aicardi-Goutières syndrome. Here, we report that RNase H2 is an essential enzyme in mice, required for embryonic growth from gastrulation onward. RNase H2 null embryos accumulate large numbers of single (or di-) ribonucleotides embedded in their genomic DNA (>1,000,000 per cell), resulting in genome instability and a p53-dependent DNA-damage response. Our findings establish RNase H2 as a key mammalian genome surveillance enzyme required for ribonucleotide removal and demonstrate that ribonucleotides are the most commonly occurring endogenous nucleotide base lesion in replicating cells.
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Affiliation(s)
- Martin A M Reijns
- Medical Research Council Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
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14
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Semple F, Dorin JR. β-Defensins: multifunctional modulators of infection, inflammation and more? J Innate Immun 2012; 4:337-48. [PMID: 22441423 DOI: 10.1159/000336619] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/17/2012] [Indexed: 12/13/2022] Open
Abstract
Defensins comprise one of the largest groups of host defence peptides, present throughout evolution, in fungi and flowering plants as well as in invertebrates and vertebrates. These cysteine-rich, cationic peptides have a common ability to kill a broad range of microorganisms including bacteria, yeast and viruses. As such, they are a strong component of the arsenal that is an organism's innate immunity. It is becoming increasingly clear, however, that antimicrobial action is only one of the numerous roles of these multifunctional peptides. In recent years, the functions of defensins in immunomodulation have been widely investigated, and their involvement in other processes (such as fertility) is becoming evident. This review addresses recent advances in the immunomodulatory activity of β-defensins as well as the involvement of β-defensins in fertility, development, wound healing and cancer.
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Affiliation(s)
- Fiona Semple
- MRC Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
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15
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Semple F, MacPherson H, Webb S, Cox SL, Mallin LJ, Tyrrell C, Grimes GR, Semple CA, Nix MA, Millhauser GL, Dorin JR. Human β-defensin 3 affects the activity of pro-inflammatory pathways associated with MyD88 and TRIF. Eur J Immunol 2011; 41:3291-300. [PMID: 21809339 PMCID: PMC3494976 DOI: 10.1002/eji.201141648] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/15/2011] [Accepted: 07/26/2011] [Indexed: 12/20/2022]
Abstract
β-Defensins are cationic host defense peptides that form an amphipathic structure stabilized by three intramolecular disulfide bonds. They are key players in innate and adaptive immunity and have recently been shown to limit the production of pro-inflammatory cytokines in TLR4-stimulated macrophages. In the present study, we investigate the mechanism underlying the anti-inflammatory effect of human β-defensin 3 (hBD3). We show that the canonical structure of hBD3 is required for this immunosuppressive effect and that hBD3 rapidly associates with and enters macrophages. Examination of the global effect of hBD3 on transcription in TLR4-stimulated macrophages shows that hBD3 inhibits the transcription of pro-inflammatory genes. Among the altered genes there is significant enrichment of groups involved in the positive regulation of NF-κB including components of Toll-like receptor signaling pathways. We confirm these observations by showing corresponding decreases in protein levels of pro-inflammatory cytokines and cell surface molecules. In addition, we show that hBD3 reduces NF-κB signaling in cells transfected with MyD88 or TRIF and that hBD3 inhibits the TLR4 response in both MyD88- and TRIF-deficient macrophages. Taken together these findings suggest that the mechanism of hBD3 anti-inflammatory activity involves specific targeting of TLR signaling pathways resulting in transcriptional repression of pro-inflammatory genes.
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Affiliation(s)
- Fiona Semple
- MRC Human Genetics Unit, IGMM, Edinburgh, Scotland, UK.
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16
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Douvaras P, Webb S, Whitaker DA, Dorà N, Hill RE, Dorin JR, West JD. Rare corneal clones in mice suggest an age-related decrease of stem cell activity and support the limbal epithelial stem cell hypothesis. Stem Cell Res 2011; 8:109-19. [PMID: 22099025 DOI: 10.1016/j.scr.2011.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 08/05/2011] [Accepted: 08/27/2011] [Indexed: 01/10/2023] Open
Abstract
The anterior ocular surface comprises the cornea, conjunctiva and a narrow intermediate region called the limbus. It is widely accepted that the corneal epithelium is maintained by stem cells but different hypotheses propose that the stem cells that maintain the mouse corneal epithelium during normal homeostasis are located either in the basal limbal epithelium or throughout the basal corneal epithelium. There are no specific markers to help test these alternatives and new methods are required to distinguish between them. We observed that KRT5(LacZ/-) transgenic mice produced rare β-galactosidase (β-gal)-positive radial stripes in the corneal epithelium. These stripes are likely to be clonal lineages of cells derived from stem cells, so they provide a lineage marker for actively proliferating stem cells. The distributions of the β-gal-positive radial stripes suggested they extended centripetally from the limbus, supporting the limbal epithelial stem cell (LESC) hypothesis. Stripe frequency declined between 15 and 30 weeks, which predicts a reduction in stem cell function with age. Pax6(+/-), KRT5(LacZ/-) corneas had small patches rather than stripes, which confirms that corneal maintenance is abnormal in Pax6(+/-) mice.
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Affiliation(s)
- Panagiotis Douvaras
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh EH8 9XD, Scotland, UK
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17
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Macmillan D, De Cecco M, Reynolds NL, Santos LFA, Barran PE, Dorin JR. Synthesis of cyclic peptides through an intramolecular amide bond rearrangement. Chembiochem 2011; 12:2133-6. [PMID: 21805553 DOI: 10.1002/cbic.201100364] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Indexed: 12/15/2022]
Affiliation(s)
- Derek Macmillan
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
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18
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Semple F, Webb S, Li HN, Patel HB, Perretti M, Jackson IJ, Gray M, Davidson DJ, Dorin JR. Human beta-defensin 3 has immunosuppressive activity in vitro and in vivo. Eur J Immunol 2010; 40:1073-8. [PMID: 20104491 PMCID: PMC2948537 DOI: 10.1002/eji.200940041] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Beta-defensins are antimicrobial peptides with an essential role in the innate immune response. In addition beta-defensins can also chemoattract cells involved in adaptive immunity. Until now, based on evidence from dendritic cell stimulation, human beta defensin-3 (hBD3) was considered pro-inflammatory. We present evidence here that hBD3 lacks pro-inflammatory activity in human and mouse primary Mphi. In addition, in the presence of LPS, hBD3 and the murine orthologue Defb14 (but not hBD2), effectively inhibit TNF-alpha and IL-6 accumulation implying an anti-inflammatory function. hBD3 also inhibits CD40/IFN-gamma stimulation of Mphi and in vivo, hBD3 significantly reduces the LPS-induced TNF-alpha level in serum. Recent work has revealed that hBD3 binds melanocortin receptors but we provide evidence that these are not involved in hBD3 immunomodulatory activity. This implies a dual role for hBD3 in antimicrobial activity and resolution of inflammation.
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Affiliation(s)
- Fiona Semple
- MRC Human Genetics Unit, Western General Hospital, Institute of Genetics and Molecular Medicine, Edinburgh, Scotland, UK.
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19
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De Cecco M, Seo ES, Clarke DJ, McCullough BJ, Taylor K, Macmillan D, Dorin JR, Campopiano DJ, Barran PE. Conformational preferences of linear beta-defensins are revealed by ion mobility-mass spectrometry. J Phys Chem B 2010; 114:2312-8. [PMID: 20102218 DOI: 10.1021/jp9111662] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In recent times there has been an enormous rise in resistance to synthetic antibiotics as well as an increase in the virulence of bacteria, the so-called "superbugs". This problem has catalyzed a search for novel molecules to fight bacteria, which in turn relies on a better understanding of the molecular basis of the immune response. Beta-defensins are a class of small, cationic, cysteine-rich antimicrobial peptides expressed by humans and other animals to act against incoming pathogens. As well as their antimicrobial properties, beta-defensins also act as chemokines, recruiting cells to the sites of infection. Here the relationship between the tertiary structures of beta-defensin analogs and their chemotactic activities has been investigated using ion mobility-mass spectrometry (IM-MS) and biochemical assays. A panel of derivatives of the murine beta-defensin Defb14 has been formed and the ability of these peptides to chemoattract the receptor CCR6 has been assessed in vitro. The derivatives can be divided into two groups, those with chemotactic activity equal to that of the unmodified parent peptide, and those whose chemotactic activity has been lost upon modification. Analysis by ion mobility-mass spectrometry reveals the conformational preferences of these peptides upon ionization from different solvents. Under denaturing conditions, the chemotactic peptides adopt more compact conformations in the gas-phase at higher charge states than those which are inactive. While the conditions of these experiments are not akin to the environment around the receptor in vivo, this technique provides an in vacuo method for distinguishing between the different chemotactic activities of beta-defensin derivatives.
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Affiliation(s)
- Martin De Cecco
- School of Chemistry, University of Edinburgh, Edinburgh, EH9 3JJ, UK
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20
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Tyrrell C, De Cecco M, Reynolds NL, Kilanowski F, Campopiano D, Barran P, Macmillan D, Dorin JR. Isoleucine/leucine2 is essential for chemoattractant activity of beta-defensin Defb14 through chemokine receptor 6. Mol Immunol 2010; 47:1378-82. [PMID: 20022113 DOI: 10.1016/j.molimm.2009.11.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 11/21/2009] [Indexed: 11/30/2022]
Abstract
Beta-defensins are both antimicrobial and able to chemoattract various immune cells including immature dendritic cells and CD4 T cells through CCR6. They are short, cationic peptides with a highly conserved six-cysteine motif. It has been shown that only the fifth cysteine is critical for chemoattraction of cells expressing CCR6. In order to identify other residues essential for functional interaction with CCR6 we used a library of peptide deletion derivatives based on Defb14. Loss of the initial two amino acids from the Defb14-1C(V) derivative destroys its ability to chemoattract cells expressing CCR6. As the second amino acid is an evolutionarily conserved leucine, we make full-length Defb14-1C(V) peptides with substitution of the leucine(2) for glycine (L2G), lysine (L2K) or isoleucine (L2I). Defb14-1C(V) L2G and L2K and are unable to chemoattract CCR6 expressing cells but the semi-conservative change L2I has activity. By circular dichroism spectroscopy we can see no evidence for a significant change in secondary structure as a consequence of these substitutions and so cannot attribute loss of chemotactic activity with disruption of the N-terminal helix. We conclude that isoleucine/leucine in the N-terminal alpha-helix region of this beta-defensin is essential for CCR6-mediated chemotaxis.
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21
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Vargues T, Morrison GJ, Seo ES, Clarke DJ, Fielder HL, Bennani J, Pathania U, Kilanowski F, Dorin JR, Govan JRW, Mackay CL, Uhrín D, Campopiano DJ. Efficient production of human beta-defensin 2 (HBD2) in Escherichia coli. Protein Pept Lett 2009; 16:668-76. [PMID: 19519528 DOI: 10.2174/092986609788490122] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human beta-defensin 2 (HBD2) has been shown to interact with pathogenic bacteria and components of the mammalian innate and adaptive immune response. We describe a quick and reliable method for the production of HBD2 in Escherichia coli. HBD2 was expressed as an insoluble fusion, chemically cleaved and oxidised to give a single, folded HBD2 beta-isoform. The purified peptide was analysed by high resolution mass spectrometry, displayed a well-dispersed (1)H NMR spectrum, was a chemoattractant to HEK293 cells expressing CCR6 and acted as an antimicrobial agent against E. coli, P. aeruginosa, C. albicans and S. aureus.
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Affiliation(s)
- Thomas Vargues
- School of Chemistry, EastChem, University of Edinburgh, Edinburgh, Scotland, Scotland, United Kingdom
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22
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Richardson J, Lundegaard PR, Reynolds NL, Dorin JR, Porteous DJ, Jackson IJ, Patton EE. mc1r Pathway regulation of zebrafish melanosome dispersion. Zebrafish 2009; 5:289-95. [PMID: 19133827 DOI: 10.1089/zeb.2008.0541] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Zebrafish rapidly alter their pigmentation in response to environmental changes. For black melanocytes, this change is due to aggregation or dispersion of melanin in the cell. Dispersion and aggregation are controlled by intracellular cyclic adenosine monophosphate (cAMP) levels, which increase upon stimulation by alpha melanocyte-stimulating hormone (alpha-MSH) or reduce with melanin-concentrating hormone (MCH). In mammals and birds, the melanocortin-1-receptor (MC1R) responds to MSH, and stimulates the synthesis of black eumelanin. While MSH-cAMP signaling stimulates melanogenesis in mammals, and melanosome dispersal in cold-blood vertebrates, the pathway components are highly conserved. However, it has only been assumed that mc1r mediates melanosome dispersal in fish. Here, using morpholino oligonucleotides designed to knockdown mc1r expression, we find that mc1r morphants are unable to disperse melanosomes when grown in dark conditions. We also use chemical modifiers of the cAMP pathway, and find an unexpected response to the specific phosphodiesterase 4 (PDE4) inhibitor, rolipram, in melanosome dispersal. When treated with the drug, melanosomes fail to fully disperse in dark conditions, despite presumed increased levels of cAMP, and in contrast to the effects of the nonselective PDE inhibitor, 3-isobutyl-1-methylxanthine. In conclusion, we demonstrate a direct role for mc1r in zebrafish melanosome dispersal in response to background, and use chemical modification of this pathway to uncover a possible new layer of regulation in melanosome dispersal in zebrafish.
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Affiliation(s)
- Jennifer Richardson
- Institute for Genetics & Molecular Medicine , MRC Human Genetics Unit and The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, United Kingdom
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23
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Kang J, Reynolds NL, Tyrrell C, Dorin JR, Macmillan D. Peptide thioester synthesis through N→S acyl-transfer: application to the synthesis of a β-defensin. Org Biomol Chem 2009; 7:4918-23. [DOI: 10.1039/b913886b] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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24
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Abstract
The beta-defensins comprise a large family of small cationic antimicrobial peptides widely distributed in plants, mammals and insects. These cysteine rich peptides display multifunctional properties with implications as potential therapeutic agents. Recent research has highlighted their role in both the innate and adaptive immune systems as well as being novel melanocortin ligands. Studies investigating structure and function provide an insight into the molecular basis of their immunological properties.
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Affiliation(s)
- Karen Taylor
- MRC Human Genetics Unit, Edinburgh, Scotland, United Kingdom
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25
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Taylor K, Clarke DJ, McCullough B, Chin W, Seo E, Yang D, Oppenheim J, Uhrin D, Govan JRW, Campopiano DJ, MacMillan D, Barran P, Dorin JR. Analysis and separation of residues important for the chemoattractant and antimicrobial activities of beta-defensin 3. J Biol Chem 2008; 283:6631-9. [PMID: 18180295 DOI: 10.1074/jbc.m709238200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
beta-Defensins are important in mammalian immunity displaying both antimicrobial and chemoattractant activities. Three canonical disulfide intramolecular bonds are believed to be dispensable for antimicrobial activity but essential for chemoattractant ability. However, here we show that HBD3 (human beta-defensin 3) alkylated with iodoactemide and devoid of any disulfide bonds is still a potent chemoattractant. Furthermore, when the canonical six cysteine residues are replaced with alanine, the peptide is no longer active as a chemoattractant. These findings are replicated by the murine ortholog Defb14. We restore the chemoattractant activity of Defb14 and HBD3 by introduction of a single cysteine in the fifth position (Cys V) of the beta-defensin six cysteine motif. In contrast, a peptide with a single cysteine at the first position (Cys I) is inactive. Moreover, a range of overlapping linear fragments of Defb14 do not act as chemoattractants, suggesting that the chemotactic activity of this peptide is not dependent solely on an epitope surrounding Cys V. Full-length peptides either with alkylated cysteine residues or with cysteine residues replaced with alanine are still strongly antimicrobial. Defb14 peptide fragments were also tested for antimicrobial activity, and peptides derived from the N-terminal region display potent antimicrobial activity. Thus, the chemoattractant and antimicrobial activities of beta-defensins can be separated, and both of these functions are independent of intramolecular disulfide bonds. These findings are important for further understanding of the mechanism of action of defensins and for therapeutic design.
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Affiliation(s)
- Karen Taylor
- Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, Scotland, United Kingdom
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26
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Affiliation(s)
- Julia R Dorin
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK.
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27
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Taylor K, McCullough B, Clarke DJ, Langley RJ, Pechenick T, Hill A, Campopiano DJ, Barran PE, Dorin JR, Govan JRW. Covalent dimer species of beta-defensin Defr1 display potent antimicrobial activity against multidrug-resistant bacterial pathogens. Antimicrob Agents Chemother 2007; 51:1719-24. [PMID: 17353239 PMCID: PMC1855538 DOI: 10.1128/aac.01531-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Beta defensins comprise a family of cationic, cysteine-rich antimicrobial peptides, predominantly expressed at epithelial surfaces. Previously we identified a unique five-cysteine defensin-related peptide (Defr1) that, when synthesized, is a mixture of dimeric isoforms and exhibits potent antimicrobial activity against Escherichia coli and Pseudomonas aeruginosa. Here we report that Defr1 displays antimicrobial activity against an extended panel of multidrug-resistant nosocomial pathogens for which antimicrobial treatment is limited or nonexistent. Defr1 fractions were collected by high-pressure liquid chromatography and analyzed by gel electrophoresis and mass spectrometry. Antimicrobial activity was initially investigated with the type strain Pseudomonas aeruginosa PAO1. All fractions tested displayed equivalent, potent antimicrobial activity levels comparable with that of the unfractionated Defr1. However, use of an oxidized, monomeric six-cysteine analogue (Defr1 Y5C), or of reduced Defr1, gave diminished antimicrobial activity. These results suggest that the covalent dimer structure of Defr1 is crucial to antimicrobial activity; this hypothesis was confirmed by investigation of a synthetic one-cysteine variant (Defr1-1cys). This gave an activity profile similar to that of synthetic Defr1 but only in an oxidized, dimeric form. Thus, we have shown that covalent, dimeric molecules based on the Defr1 beta-defensin sequence demonstrate antimicrobial activity even in the absence of the canonical cysteine motif.
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Affiliation(s)
- Karen Taylor
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, Scotland, UK
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28
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Abstract
Defensins are small cationic peptides involved in innate immunity and are components of the first line of defence against invading pathogens. beta-defensins are a subgroup of the defensin family that display a particular cysteine spacing and pattern of intramolecular bonding. These molecules are produced mostly by epithelia lining exposed surfaces and appear to have both antimicrobial and cell signalling functions. The unusually high degree of sequence variation in the mature peptide produced by the paralogous and in some cases orthologous genes implies extensive specialisation and species specific adaptation. Here we review recent functional data that are an important addition to our knowledge of the innate immune response and novel antibiotic design. We also consider the organisation and evolution of the genomic loci harbouring these genes where radical and rapid changes in beta-defensin sequences have been shown to result from the interplay of both positive and negative selection. Consequently these genes provide some unusually clear glimpses of the processes of duplication and specialisation that have shaped the mammalian genome.
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Affiliation(s)
- Colin A Semple
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, UK
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MacPherson H, Keir PA, Edwards CJ, Webb S, Dorin JR. Following damage, the majority of bone marrow-derived airway cells express an epithelial marker. Respir Res 2006; 7:145. [PMID: 17177981 PMCID: PMC1764737 DOI: 10.1186/1465-9921-7-145] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 12/19/2006] [Indexed: 11/10/2022] Open
Abstract
Background Adult-derived bone marrow stem cells are capable of reconstituting the haematopoietic system. However there is ongoing debate in the literature as to whether bone marrow derived cells have the ability to populate other tissues and express tissue specific markers. The airway has been an organ of major interest and was one of the first where this was demonstrated. We have previously demonstrated that the mouse airway can be repopulated by side population bone marrow transplanted cells. Here we investigate the frequency and phenotypic nature of these bone marrow derived cells. Methods Female mice were engrafted with male whole bone marrow or side population (SP) cells and subjected to detergent-induced damage after 3 months. Donor cells were identified by Y chromosome fluorescence in situ hybridisation and their phenotype was assessed by immunohistochemistry on the same sections. Slides were visualised by a combination of widefield and deconvolved microscopy and whole cells were analysed on cytospin preparations. Results The frequencies of engraftment of male cells in the airway of mice that show this (9/10), range from 1.0 – 1.6% with whole marrow and 0.6 – 1.5% with SP cells. Undamaged controls have only between 0.1 and 0.2% male cells in the trachea. By widefield microscopy analysis we find 60.2% (53/88) of male donor derived cells express cytokeratins as a marker of epithelial cells. These results were reinforced using deconvolved microscopy and scored by two independent investigators. In addition cytospin analysis of cells dissociated from the damaged trachea of engrafted mice also reveals donor derived Y chromosome positive cells that are immunopositive for cytokeratin. Using cytokeratin and the universal haematopoietic marker CD45 immunohistochemistry, we find the donor derived cells fall into four phenotypic classes. We do not detect cytokeratin positive cells in whole bone marrow using cytokeratin immunostaining and we do not detect any cytokeratin mRNA in SP or bone marrow samples by RT-PCR. Conclusion The appearance of bone marrow derived cells in the tracheal epithelium is enriched by detergent-induced tissue damage and the majority of these cells express an epithelial marker. The cytokeratin positive donor derived cells in the tracheal epithelium are not present in the injected donor cells and must have acquired this novel phenotype in vivo.
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Affiliation(s)
- Heather MacPherson
- MRC Human Genetics Unit, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Pamela A Keir
- MRC Human Genetics Unit, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Carol J Edwards
- MRC Human Genetics Unit, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Sheila Webb
- MRC Human Genetics Unit, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK
| | - Julia R Dorin
- MRC Human Genetics Unit, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK
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Semple CAM, Taylor K, Eastwood H, Barran PE, Dorin JR. β-Defensin evolution: selection complexity and clues for residues of functional importance. Biochem Soc Trans 2006; 34:257-62. [PMID: 16545088 DOI: 10.1042/bst20060257] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have examined the evolution of the genes at the major human beta-defensin locus and the orthologous loci in a range of other primates and mammals. For the first time, these data allow us to examine selective episodes in the more recent evolutionary history of this locus as well as in the ancient past. We have used a combination of maximum-likelihood-based tests and a maximum-parsimony-based sliding window approach to give a detailed view of the varying modes of selection operating at this locus. We provide evidence for strong positive selection soon after the duplication of these genes within an ancestral mammalian genome. During the divergence of primates, however, variable selective pressures have acted on beta-defensin genes in different evolutionary lineages, with episodes of both negative and, more rarely, positive selection. Positive selection appears to have been more common in the rodent lineage, accompanying the birth of novel rodent-specific beta-defensin gene clades. Sites in the second exon have been subject to positive selection and, by implication, are important in functional diversity. A small number of sites in the mature human peptides were found to have undergone repeated episodes of selection in different primate lineages. Particular sites were consistently implicated by multiple methods at positions throughout the mature peptides. These sites are clustered at positions that are predicted to be important for the function of beta-defensins.
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Affiliation(s)
- C A M Semple
- MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, Scotland, UK
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McMichael JW, Maxwell AI, Hayashi K, Taylor K, Wallace WA, Govan JR, Dorin JR, Sallenave JM. Antimicrobial activity of murine lung cells against Staphylococcus aureus is increased in vitro and in vivo after elafin gene transfer. Infect Immun 2005; 73:3609-17. [PMID: 15908390 PMCID: PMC1111862 DOI: 10.1128/iai.73.6.3609-3617.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a pathogen often found in pneumonia and sepsis. In the context of the resistance of this organism to conventional antibiotics, an understanding of the regulation of natural endogenous antimicrobial molecules is of paramount importance. Previous studies have shown that both human and mouse airways express a variety of these molecules, including defensins, cathelicidins, and the four-disulfide core protein secretory leukocyte protease inhibitor. We demonstrate here by culturing mouse tracheal epithelial cells at an air-liquid interface that, despite the production of Defb1, Defb14, and Defr1 in this system, these cells are unable to clear S. aureus when exposed to this respiratory pathogen. Using an adenovirus (Ad)-mediated gene transfer strategy, we show that overexpression of elafin, an anti-elastase/antimicrobial molecule (also a member of the four-disulfide core protein family), dramatically improves the clearance of S. aureus. In addition, we also demonstrate that this overexpression is efficient in vivo and that intratracheal instillation of Ad-elafin significantly reduced the lung bacterial load and demonstrates concomitant anti-inflammatory activity by reducing neutrophil numbers and markers of lung inflammation, such as bronchoalveolar lavage levels of tumor necrosis factor and myeloperoxidase. These findings show that an increased antimicrobial activity phenotype is provided by the elafin molecule and have implications for its use in S. aureus-associated local and systemic infections.
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Affiliation(s)
- J W McMichael
- Rayne Laboratory, Respiratory Medicine Unit, MRC Centre for Inflammation Research, University of Edinburgh, Edinburgh EH8 9AG, Scotland, United Kingdom
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Semple CAM, Maxwell A, Gautier P, Kilanowski FM, Eastwood H, Barran PE, Dorin JR. The complexity of selection at the major primate beta-defensin locus. BMC Evol Biol 2005; 5:32. [PMID: 15904491 PMCID: PMC1156880 DOI: 10.1186/1471-2148-5-32] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 05/18/2005] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND We have examined the evolution of the genes at the major human beta-defensin locus and the orthologous loci in a range of other primates and mouse. For the first time these data allow us to examine selective episodes in the more recent evolutionary history of this locus as well as the ancient past. We have used a combination of maximum likelihood based tests and a maximum parsimony based sliding window approach to give a detailed view of the varying modes of selection operating at this locus. RESULTS We provide evidence for strong positive selection soon after the duplication of these genes within an ancestral mammalian genome. Consequently variable selective pressures have acted on beta-defensin genes in different evolutionary lineages, with episodes both of negative, and more rarely positive selection, during the divergence of primates. Positive selection appears to have been more common in the rodent lineage, accompanying the birth of novel, rodent-specific beta-defensin genes. These observations allow a fuller understanding of the evolution of mammalian innate immunity. In both the rodent and primate lineages, sites in the second exon have been subject to positive selection and by implication are important in functional diversity. A small number of sites in the mature human peptides were found to have undergone repeated episodes of selection in different primate lineages. Particular sites were consistently implicated by multiple methods at positions throughout the mature peptides. These sites are clustered at positions predicted to be important for the specificity of the antimicrobial or chemoattractant properties of beta-defensins. Surprisingly, sites within the prepropeptide region were also implicated as being subject to significant positive selection, suggesting previously unappreciated functional significance for this region. CONCLUSIONS Identification of these putatively functional sites has important implications for our understanding of beta-defensin function and for novel antibiotic design.
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Affiliation(s)
- Colin AM Semple
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Alison Maxwell
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Philippe Gautier
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Fiona M Kilanowski
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Hayden Eastwood
- School of Chemistry, The University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh, EH9 3JJ, UK
| | - Perdita E Barran
- School of Chemistry, The University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh, EH9 3JJ, UK
| | - Julia R Dorin
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
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Campopiano DJ, Clarke DJ, Polfer NC, Barran PE, Langley RJ, Govan JRW, Maxwell A, Dorin JR. Structure-Activity Relationships in Defensin Dimers. J Biol Chem 2004; 279:48671-9. [PMID: 15317821 DOI: 10.1074/jbc.m404690200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Defensins are cationic antimicrobial peptides that have a characteristic six-cysteine motif and are important components of the innate immune system. We recently described a beta-defensin-related peptide (Defr1) that had potent antimicrobial activity despite having only five cysteines. Here we report a relationship between the structure and activity of Defr1 through a comparative study with its six cysteine-containing analogue (Defr1 Y5C). Against a panel of pathogens, we found that oxidized Defr1 had significantly higher activity than its reduced form and the oxidized and reduced forms of Defr1 Y5C. Furthermore, Defr1 displayed activity against Pseudomonas aeruginosa in the presence of 150 mm NaCl, whereas Defr1 Y5C was inactive. By using nondenaturing gel electrophoresis and Fourier transform ion cyclotron resonance mass spectrometry, we observed Defr1 and Defr1 Y5C dimers. Two complementary fragmentation techniques (collision-induced dissociation and electron capture dissociation) revealed that Defr1 Y5C dimers form by noncovalent, weak association of monomers that contain three intramolecular disulfide bonds. In contrast, Defr1 dimers are resistant to collision-induced dissociation and are only dissociated into monomers by reduction using electron capture. This is indicative of Defr1 dimerization being mediated by an intermolecular disulfide bond. Proteolysis and peptide mass mapping revealed that Defr1 Y5C monomers have beta-defensin disulfide bond connectivity, whereas oxidized Defr1 is a complex mixture of dimeric isoforms with as yet unknown inter- and intramolecular connectivities. Each isoform contains one intermolecular and four intramolecular disulfide bonds, but because we were unable to resolve the isoforms by reverse phase chromatography, we could not assign each isoform with a specific antimicrobial activity. We conclude that the enhanced activity and stability of this mixture of Defr1 dimeric isoforms are due to the presence of an intermolecular disulfide bond. This first description of a covalently cross-linked member of the defensin family provides further evidence that the antimicrobial activity of a defensin is linked to its ability to form stable higher order structures.
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Affiliation(s)
- Dominic J Campopiano
- School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK
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Davidson DJ, Webb S, Teague P, Govan JRW, Dorin JR. Lung pathology in response to repeated exposure to Staphylococcus aureus in congenic residual function cystic fibrosis mice does not increase in response to decreased CFTR levels or increased bacterial load. Pathobiology 2004; 71:152-8. [PMID: 15051928 DOI: 10.1159/000076470] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2003] [Accepted: 10/23/2003] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To establish the role of defects in murine Cftr in the susceptibility to Staphylococcus aureus lung disease using mouse models of cystic fibrosis (CF), congenic or inbred strains. METHODS We describe the histopathological analyses of CF mice repeatedly exposed by aerosolisation to a CF isolate of S. aureus, using residual function Cftr mice and compound heterozygotes generated by intercrossing these with Cftr 'null' mice, all congenic on the C57Bl6/N background. RESULTS We demonstrate that mice congenic on the C57Bl/6 background develop significantly more severe lung pathology than non-CF littermates in response to repeated exposure to the most frequent early CF lung pathogen S. aureus. Furthermore, reducing the level of Cftr by half in compound heterozygote mice does not impact upon disease severity, even in response to an increased bacterial dose. CONCLUSIONS These results are consistent with an airway clearance defect, or abnormal inflammatory response secondary to Cftr mutation. These studies confirm the primary role for Cftr mutation in the development of this lung phenotype. In addition, these results demonstrate that a further 50% decrease in residual wild-type Cftr mRNA levels in this model does not impact the severity of the histopathological response to S. aureus, suggesting a critical threshold level for functional CFTR.
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Abstract
We describe an air-liquid interface primary culture method for murine tracheal epithelial cells on semi-permeable membranes, forming polarized epithelia with a high transepithelial resistance, differentiation to ciliated and secretory cells, and physiologically appropriate expression of key genes and ion channels. We also describe the isolation of primary murine nasal epithelial cells for patch-clamp analysis, generating polarised cells with physiologically appropriate distribution and ion channel expression. These methods enable more physiologically relevant analysis of murine airway epithelial cells in vitro and ex vivo, better utilisation of transgenic mouse models of human pulmonary diseases, and have been approved by the European Working Group on CFTR expression.
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Affiliation(s)
- Donald J Davidson
- B.C. Research Institute, Room 381, University of British Columbia, 950 West 28th Avenue, Vancouver, BC, Canada V5Z 4H4.
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36
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Charizopoulou N, Jansen S, Dorsch M, Stanke F, Dorin JR, Hedrich HJ, Tümmler B. Instability of the insertional mutation in CftrTgH(neoim)Hgu cystic fibrosis mouse model. BMC Genet 2004; 5:6. [PMID: 15102331 PMCID: PMC419339 DOI: 10.1186/1471-2156-5-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Accepted: 04/21/2004] [Indexed: 11/22/2022] Open
Abstract
Background A major boost to the cystic fibrosis disease research was given by the generation of various mouse models using gene targeting in embryonal stem cells. Moreover, the introduction of the same mutation on different inbred strains generating congenic strains facilitated the search for modifier genes. From the original CftrTgH(neoim)Hgu CF mouse model we have generated using strict brother × sister mating two inbred CftrTgH(neoim)Hgu mouse lines (CF/1 and CF/3). Thereafter, the insertional mutation was introgressed from CF/3 into three inbred backgrounds (C57BL/6, BALB/c, DBA/2J) generating congenic animals. In every backcross cycle germline transmission of the insertional mutation was monitored by direct probing the insertion via Southern RFLP. In order to bypass this time consuming procedure we devised an alternative PCR based protocol whereby mouse strains are differentiated at the Cftr locus by Cftr intragenic microsatellite genotypes that are tightly linked to the disrupted locus. Results Using this method we were able to identify animals carrying the insertional mutation based upon the differential haplotypic backgrounds of the three inbred strains and the mutant CftrTgH(neoim)Hgu at the Cftr locus. Moreover, this method facilitated the identification of the precise vector excision from the disrupted Cftr locus in two out of 57 typed animals. This reversion to wild type status took place without any loss of sequence revealing the instability of insertional mutations during the production of congenic animals. Conclusions We present intragenic microsatellite markers as a tool for fast and efficient identification of the introgressed locus of interest in the recipient strain during congenic animal breeding. Moreover, the same genotyping method allowed the identification of a vector excision event, posing questions on the stability of insertional mutations in mice.
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Affiliation(s)
- Nikoletta Charizopoulou
- Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
| | - Silke Jansen
- Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
| | - Martina Dorsch
- Zentrales Tierlaboratorium, OE 8600, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
| | - Frauke Stanke
- Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
| | - Julia R Dorin
- MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Hans-Jürgen Hedrich
- Zentrales Tierlaboratorium, OE 8600, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
| | - Burkhard Tümmler
- Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
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Abstract
beta-Defensin genes encode broad spectrum antimicrobial cationic peptides. We have analysed the largest murine and human clusters of these genes, which localise to mouse and human chromosome 8. Using hidden Markov models, we identified novel mouse and human beta-defensin genes. We subsequently found full-length expressed transcripts for these novel genes. Expression in the mouse was high in brain and reproductive tissues. Fourteen murine beta-defensins could be grouped into two clear sub-groups by virtue of their position and high signal sequence (exon 1 encoded) identity. In contrast, there was a very low level of sequence conservation in the exon 2 region encoding the mature antimicrobial peptide. Evolutionary analysis revealed strong evidence that following gene duplication, exon 1 and surrounding non-coding DNA show little divergence within subfamilies. The focus for rapid sequence divergence is localised in the DNA encoding the mature peptide and this is driven by accelerated positive selection. In the human we also conclude that the locus has evolved by successive rounds of duplication followed by substantial divergence involving positive selection, to produce a diverse cluster of paralogous genes prior to human-baboon divergence. This mechanism of adaptive evolution is consistent with the role of this gene family as defence against bacterial pathogens. In order to look at function of these rapidly evolving genes, we characterised one of the novel mouse beta-defensin genes. This gene deviates from the canonical six cysteine motif present in the mature functional peptide of all other beta defensins. This defensin related gene (Defr1) is most highly expressed in testis and heart and the genomic organisation is highly similar to Defb3-6. A synthetic Defr1 peptide was shown to exist as a dimer and yet displayed both antimicrobial and chemotactic activity. The antimicrobial activity of Defr1 against S. aureus, E. coli and B. cepacia was found to be reduced in raised concentration of NaCl, but its action against P. aeruginosa was independent of NaCl concentration. These data have major implications on the structure and functions of these important host defence molecules.
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Affiliation(s)
- A I Maxwell
- MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, UK
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Larbig M, Jansen S, Dorsch M, Bernhard W, Bellmann B, Dorin JR, Porteous DJ, Von Der Hardt H, Steinmetz I, Hedrich HJ, Tuemmler B, Tschernig T. Residual cftr expression varies with age in cftr(tm1Hgu) cystic fibrosis mice: impact on morphology and physiology. Pathobiology 2003; 70:89-97. [PMID: 12476034 DOI: 10.1159/000067308] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mouse models for cystic fibrosis (CF) mimic intestinal manifestations of the human disease, but the lung disease phenotypes are lacking in most strains. In this work, the issue was addressed whether aging of the respiratory tract leads to lung pathophysiology in the exon 10 insertional mutant cftr(tm1Hgu) mouse. Weight gain, body weight and life-span of cftr(tm1Hgu) mice were significantly reduced compared with control mice. cftr(tm1Hgu) mice expressed 20, 21 or 37% (median) of wild-type cystic fibrosis conductance transmembrane regulator (cftr) mRNA transcript in lungs, intestine and kidney. Wild-type cftr mRNA in renal and respiratory epithelia varied with age from levels similar to Ztm:MF1 controls at the age of 2 and 4 months to levels seen in patients with CFTR splice mutations beyond the age of 6 months. The morphology of the bronchi and more distal airways was apparently normal in cftr(tm1Hgu) mice during their first year of life. The alveolar surfactant phospholipid pool was increased in cftr(tm1Hgu) mice by 1.5- to 2-fold compared with Ztm:MF1 controls. Alveolar clearance of gamma-labelled scandium oxide - the first report of lung clearance measurement in living mice - was reduced in cftr(tm1Hgu) mice compared with littermate controls. Although no progressive lung pathology was seen in the cftr expression of cftr(tm1Hgu) mice, surfactant phospholipid homeostasis, and alveolar and mucociliary clearance were abnormal. Therefore, the described model is useful for studying the initial CF lung pathophysiology.
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Affiliation(s)
- M Larbig
- Fraunhofer Institute Toxicology and Aerosol Research, Medical School of Hannover, Hannover, Germany
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Semple CAM, Rolfe M, Dorin JR. Duplication and selection in the evolution of primate beta-defensin genes. Genome Biol 2003; 4:R31. [PMID: 12734011 PMCID: PMC156587 DOI: 10.1186/gb-2003-4-5-r31] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2003] [Revised: 03/18/2003] [Accepted: 04/03/2003] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Innate immunity is the first line of defense against microorganisms in vertebrates and acts by providing an initial barrier to microorganisms and triggering adaptive immune responses. Peptides such as beta-defensins are an important component of this defense, providing a broad spectrum of antimicrobial activity against bacteria, fungi, mycobacteria and several enveloped viruses. Beta-defensins are small cationic peptides that vary in their expression patterns and spectrum of pathogen specificity. Disruptions in beta-defensin function have been implicated in human diseases, including cystic fibrosis, and a fuller understanding of the variety, function and evolution of human beta-defensins might form the basis for novel therapies. Here we use a combination of laboratory and computational techniques to characterize the main human beta-defensin locus on chromosome 8p22-p23. RESULTS In addition to known genes in the region we report the genomic structures and expression patterns of four novel human beta-defensin genes and a related pseudogene. These genes show an unusual pattern of evolution, with rapid divergence between second exon sequences that encode the mature beta-defensin peptides matched by relative stasis in first exons that encode signal peptides. CONCLUSIONS We conclude that the 8p22-p23 locus has evolved by successive rounds of duplication followed by substantial divergence involving positive selection, to produce a diverse cluster of paralogous genes established before the human-baboon divergence more than 23 million years ago. Positive selection, disproportionately favoring alterations in the charge of amino-acid residues, is implicated as driving second exon divergence in these genes.
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Affiliation(s)
- Colin A M Semple
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK.
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Morrison GM, Semple CAM, Kilanowski FM, Hill RE, Dorin JR. Signal sequence conservation and mature peptide divergence within subgroups of the murine beta-defensin gene family. Mol Biol Evol 2003; 20:460-70. [PMID: 12644567 DOI: 10.1093/molbev/msg060] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Beta-defensins are two exon genes which encode broad spectrum antimicrobial cationic peptides. We have analyzed the largest murine cluster of these genes which localizes to chromosome 8. Using hidden Markov models, we identified six beta-defensin exon 2-like sequences and subsequently found full-length expressed transcripts for these novel genes. Expression was high in brain and reproductive tissues. Eleven beta-defensins could be grouped into two clear subgroups by virtue of their position and high signal sequence (exon 1 encoded) identity. In contrast, however, there was a very low level of sequence conservation in the exon 2 region encoding the mature antimicrobial peptide. Examination of the gene sequences of orthologs in other rodents also revealed an excess of nucleotide changes that altered amino acids in the mature peptide region. Evolutionary analysis revealed strong evidence that following gene duplication, exon 1 and surrounding noncoding DNA show little divergence within subgroups. The focus for rapid sequence divergence is localized in the DNA encoding the mature peptide and this is driven by accelerated positive selection. This mechanism of evolution is consistent with the role of this gene family as defense against bacterial pathogens and the sequence changes have implications for novel antibiotic design.
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Morrison GM, Rolfe M, Kilanowski FM, Cross SH, Dorin JR. Identification and characterization of a novel murine beta-defensin-related gene. Mamm Genome 2002; 13:445-51. [PMID: 12226710 DOI: 10.1007/s00335-002-3014-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2002] [Accepted: 04/11/2002] [Indexed: 10/26/2022]
Abstract
Beta-defensins comprise a family of cationic peptides, which are predominately expressed at epithelial surfaces and have a broad-range antimicrobial activity. We have assembled two BAC-based contigs from the chromosomal region 8A4 that contain the murine defensins, and we have mapped six reported beta-defensin genes. In addition, we have isolated and functionally characterized a novel beta-defensin gene that deviates from the canonical six cysteine motif present in the mature functional peptide of all other beta-defensins. This defensin-related gene (Defr1) is most highly expressed in testis and heart. The genomic organization is highly similar to Defb3, 4, 5, and 6, and the exon 1 sequence is very highly conserved. A synthetic Defr1 peptide displayed antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Burkholderia cepacia. The antimicrobial activity of Defr1 against S. aureus, E.coli, and B. cepacia was found to be reduced in raised concentration of NaCl, but its action against P. aeruginosa was independent of NaCl concentration. This is the first report of a functional beta defensin that lacks one of the conserved cysteine residues in its predicted mature peptide. This study has major implications for the structure and functions of these important host defense molecules.
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Affiliation(s)
- Gillian M Morrison
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, Scotland, UK
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Harmar AJ, Marston HM, Shen S, Spratt C, West KM, Sheward WJ, Morrison CF, Dorin JR, Piggins HD, Reubi JC, Kelly JS, Maywood ES, Hastings MH. The VPAC(2) receptor is essential for circadian function in the mouse suprachiasmatic nuclei. Cell 2002; 109:497-508. [PMID: 12086606 DOI: 10.1016/s0092-8674(02)00736-5] [Citation(s) in RCA: 422] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The neuropeptides pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are implicated in the photic entrainment of circadian rhythms in the suprachiasmatic nuclei (SCN). We now report that mice carrying a null mutation of the VPAC(2) receptor for VIP and PACAP (Vipr2(-/-)) are incapable of sustaining normal circadian rhythms of rest/activity behavior. These mice also fail to exhibit circadian expression of the core clock genes mPer1, mPer2, and mCry1 and the clock-controlled gene arginine vasopressin (AVP) in the SCN. Moreover, the mutants fail to show acute induction of mPer1 and mPer2 by nocturnal illumination. This study highlights the role of intercellular neuropeptidergic signaling in maintenance of circadian function within the SCN.
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Affiliation(s)
- Anthony J Harmar
- Department of Neuroscience, University of Edinburgh, 1 George Square, United Kingdom.
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Dickinson P, Smith SN, Webb S, Kilanowski FM, Campbell IJ, Taylor MS, Porteous DJ, Willemsen R, de Jonge HR, Farley R, Alton EWFW, Dorin JR. The severe G480C cystic fibrosis mutation, when replicated in the mouse, demonstrates mistrafficking, normal survival and organ-specific bioelectrics. Hum Mol Genet 2002; 11:243-51. [PMID: 11823443 DOI: 10.1093/hmg/11.3.243] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The majority of cystic fibrosis patients produce a mutant form of CFTR (DeltaF508) which has been shown to be mislocalized in both humans and mice. G480C, another clinically 'severe' mutation, has also been demonstrated to be defective in its intracellular processing, but when allowed to traffic in Xenopus oocytes showed similar channel characteristics to that of wild-type CFTR. We have replicated the G480C mutation in the murine Cftr gene using the 'hit and run' double recombination procedure. As expected, the G480C cystic fibrosis mouse model expresses the G480C mutant transcript at a level comparable to that of wild-type CFTR: The homozygous mutant mice were fertile, had normal survival, weight, tooth colour and no evidence of caecal blockage, despite mild goblet cell hypertrophy in the intestine. Analysis of the mutant protein revealed that the majority of G480C CFTR was abnormally processed and no G480C CFTR-specific immunostaining in the apical membranes of intestinal cells was detected. The bioelectric phenotype of these mice revealed organ-specific electrophysiological effects. In contrast to DeltaF508 'hit and run' homozygotes, the classic defect of forskolin-induced chloride ion transport is not replicated in the caecum, but the response to low chloride in the nose is clearly defective in the G480C mutant animals. The mild phenotype of these G480C mutant animals combined with the defective chloride transport in the nose uniquely provides a valuable resource to test novel pharmacological agents aimed at improving trafficking and correcting the electrophysiological defect in the respiratory tract.
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Affiliation(s)
- Paul Dickinson
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
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44
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Abstract
It is generally important to elucidate airway epithelial cell lineages and to identify multipotent progenitors as targets for gene therapy. Stem (S) cells are typically present in specialized compartments spatially proximal to their differentiated progeny, but an equivalent paradigm has not been demonstrated in the airway. We discovered a distinct population of cells displaying high levels of keratin expression in murine tracheal submucosal gland ducts, and tested the hypothesis that bromodeoxyuridine (BrdU) label-retaining cells (LRCs), thought to represent the S-cells, were present in this compartment. Mice received weekly epithelial damage by intratracheal detergent or SO(2) inhalation for 4 wk and received intraperitoneal injections of BrdU every 48 h during the injury and repair period. At 3 and 6 d after injury, BrdU-positive epithelial cells were noted along the entire tracheal length in both basal and lumenal cell positions. At later time points (20 and 95 d) LRCs were localized to gland ducts in the upper trachea and to systematically arrayed foci in the lower trachea, typically near the cartilage-intercartilage junction. LRCs were not pulmonary neuroendocrine cells. Heterotopic tracheal grafts after surface epithelial removal demonstrated reconstitution of a surface-like epithelium from gland remnants. These results suggest that airway epithelial S cells are localized to specific niches.
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Affiliation(s)
- D W Borthwick
- Medical Research Council Human Genetics Unit, Edinburgh, United Kingdom
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45
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Affiliation(s)
- D J Davidson
- Comparative and Developmental Genetics Section, MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH34 2XU, UK
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46
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Abstract
Submucosal glands (SMG) are important secretory glands that are present in the major airways and bronchioles of humans. In mice the structure, cellular composition, and density of SMG are similar to those seen in humans, but the glands are present only in the trachea. Characterization of SMG is important as they secrete bacteriocidal products such as lactoferrin, lysozyme, and defensins believed to be of importance in the innate defense system. Serous cells in SMG are the primary site of cystic fibrosis transmembrane conductance regulator (CFTR) gene expression and the initial site of histological abnormality in cystic fibrosis (CF) individuals. In this study, we examined four inbred strains of mice (A/J, C57BL/6N, FVB/N, and BALB/CAnN) and revealed that the extent to which glands descend in the mouse trachea varied between inbred strains. In particular, the A/J and C57BL/6N strains exhibited few SMG extending further than the first or second intercartilaginous space (mean depth of 0.4+/-0.11 and 1.5+/-0.32 tracheal rings respectively) in the trachea, whereas the FVB/N and BALB/CAnN strains had SMG extending beyond the fourth space (mean depths of 3.3+/-0.46 and 5.6+/-0.45 rings respectively). We have previously shown that in congenic C57Bl/ 6N Cftr mutant mice (CF mice), the SMG are distributed more distally than in wild-type C57Bl/6N but are indistinguishable from BALB/CAnN wild-type or CF mice. The implication that SMG distribution is influenced by Cftr gene expression (or a gene closely linked to Cftr) led us to investigate the genetic difference between C57Bl6/N and BALB/CAnN mice. In recombinant inbred strain (RIS) analysis (with BALB/CJ and C57BL/6J progenitors), two loci were identified as being linked to the SMG phenotype (peak likelihood statistic levels of 8.8 and 9.9 on Chrs 9 and 10 respectively, indicating suggestive linkage). A subsequent segregation analysis of an F2 intercross between the C57BL/6N and BALB/CAnN mice indicated that there were at least two major genetic factors responsible for SMG distribution. The loci indicated in the RI analysis were included in a targeted genome scan involving 235 F2 intercross animals (C57BL/6N and BALB/CAnN strain intercross). The genome scan confirmed the locus on Chr 9 (between genetic markers D9Mit11 and D9Mit182), designated Smgdl, as significantly linked to the SMG distribution phenotype (peak LOD score 5.8) within a 95% confidence interval of 12 cM.
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Affiliation(s)
- B A Innes
- Medical Research Council--Human Genetics Unit, Western General Hospital, Edinburgh, UK
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47
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Davidson DJ, Kilanowski FM, Randell SH, Sheppard DN, Dorin JR. A primary culture model of differentiated murine tracheal epithelium. Am J Physiol Lung Cell Mol Physiol 2000; 279:L766-78. [PMID: 11000138 DOI: 10.1152/ajplung.2000.279.4.l766] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The goal of this study was to develop a primary culture model of differentiated murine tracheal epithelium. When grown on semipermeable membranes at an air interface, dissociated murine tracheal epithelial cells formed confluent polarized epithelia with high transepithelial resistances ( approximately 12 kOmega. cm(2)) that remained viable for up to 80 days. Immunohistochemistry and light and electron microscopy demonstrated that the cells were epithelial in nature (cytokeratin positive, vimentin and alpha-smooth muscle actin negative) and differentiated to form ciliated and secretory cells from day 8 after seeding onward. With RT-PCR, expression of the cystic fibrosis transmembrane conductance regulator (Cftr) and murine beta-defensin (Defb) genes was detected (Defb-1 was constitutively expressed, whereas Defb-2 expression was induced by exposure to lipopolysaccharide). Finally, Ussing chamber experiments demonstrated an electrophysiological profile compatible with functional amiloride-sensitive sodium channels and cAMP-stimulated CFTR chloride channels. These data indicate that primary cultures of murine tracheal epithelium have many characteristics similar to those of murine tracheal epithelium in vivo. This method will facilitate the establishment of primary cultures of airway epithelium from transgenic mouse models of human diseases.
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Affiliation(s)
- D J Davidson
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
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48
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Dickinson P, Kimber WL, Kilanowski FM, Webb S, Stevenson BJ, Porteous DJ, Dorin JR. Enhancing the efficiency of introducing precise mutations into the mouse genome by hit and run gene targeting. Transgenic Res 2000; 9:55-66. [PMID: 10853269 DOI: 10.1023/a:1008915026660] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The creation of precise clinical mutations by targeting is important in elucidating disease pathogenesis using mouse models. 'Hit and run' gene targeting is an elegant method to achieve this goal. This uses first a positive selection to introduce the targeting vector carrying the required mutation and then a negative selection to identify clones which have removed vector and wild-type sequences by intrachromosomal recombination. However, this approach has only been successfully used in a handful of cases. We used this procedure to introduce precise clinical mutations into the exon 10 region of the cystic fibrosis transmembrane conductance regulator (Cftr) gene. Using a CMV promoter driven hygromycin/thymidine kinase (hyg/tk) fusion gene as both our dominant and negative selectable marker, we targeted the Cftr locus very efficiently but only identified false runs after the negative selection step. This defect in thymidine kinase induced toxicity to gancyclovir correlated with methylation of the transgene. Consequently we devised a stringent screening procedure to select only true 'run' clones. Unfortunately these 'run' clones had lost the mutation so we altered the vector design to bias the run step to retain the mutation and used a different tk selection cassette with a HSVtk promoter sequence. This new vector design allowed both efficient 'hit and run' for two cystic fibrosis (CF) mutations with no false positives and successful germline transmission of the novel G480C missense mutation.
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Affiliation(s)
- P Dickinson
- MRC Human Genetics Unit, Western General Hospital, Edinburgh
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49
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Abstract
We present here an in vivo mouse model for intestinal stem cell function and differentiation that uses postnatal intestinal epithelial cell aggregates to generate a differentiated murine small intestinal mucosa with full crypt-villus architecture. The process of neomucosal formation is highly similar to that of intestinal regeneration. Both in vivo grafting and primary culture of these cells reveal two different epithelial cell populations, which display properties consistent with intestinal epithelial transit amplifying and stem cell populations. Using this model system with a mixture of wild-type and transgene marked cells, we have shown that neomucosae originally develop from single aggregates, but that over time the mucosae fuse to form chimaeric mucosae. Despite fusion, the chimaeric mucosae maintain crypt clonality and villus polyclonality, demonstrating that clonal segregation persists during intestinal epithelial regeneration.
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Affiliation(s)
- E M Slorach
- Molecular Genetics Section, MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK. . uk
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50
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Borthwick DW, West JD, Keighren MA, Flockhart JH, Innes BA, Dorin JR. Murine submucosal glands are clonally derived and show a cystic fibrosis gene-dependent distribution pattern. Am J Respir Cell Mol Biol 1999; 20:1181-9. [PMID: 10340937 DOI: 10.1165/ajrcmb.20.6.3475] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Submucosal glands (SMGs) are the major site of expression of the cystic fibrosis (CF) transmembrane conductance regulator gene (CFTR) in the human lung. As such, SMGs may be a critical component of CF lung disease pathogenesis and an important target for gene therapy. Gene-targeted mouse models exist for CF and these are used to validate gene therapy or other interventions and to dissect CF phenotypes. It is important, therefore, to compare human and mouse SMGs. We show that SMGs in the mouse are similar in structure, cell types, and Cftr expression to those in the human. Murine SMGs were found to be present in the proximal regions of the trachea at the same density as in humans but, unlike in humans, did not extend below the trachea. Upon investigation of homozygous Cftr tm1HGU and Cftr tm1G551D mutant mice, SMGs were found to extend more distally than those in wild-type control mice (P < 0.05). To investigate the development of SMGs we generated aggregation chimeric mice. Chimeric offspring contained a contribution of transgenic cells that were detectable either by DNA in situ hybridization (reiterated beta-globin transgene TgN[Hbb-bl]83Clo) or beta-galactosidase histochemistry (Lac Z reporter gene TgR[ROSA26]- 26Sor). Analysis of the distribution of transgenic cells in chimeric SMGs suggests that SMGs are clonally derived.
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Affiliation(s)
- D W Borthwick
- MRC Human Genetics Unit, University of Edinburgh, Centre for Reproductive Biology, Edinburgh, United Kingdom
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