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Jin G, Zou M, Li L, Liu Z, Young C, Qi H, Zheng D. Corneal biomechanics and their association with severity of lens dislocation in Marfan syndrome. Int Ophthalmol 2024; 44:148. [PMID: 38502381 DOI: 10.1007/s10792-024-03079-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 02/16/2024] [Indexed: 03/21/2024]
Abstract
PURPOSE To investigate corneal biomechanical properties and its associations with the severity of lens dislocation in patients with Marfan syndrome. METHODS A total of 30 patients with Marfan syndrome and 30 age-, sex- and axial length (AL)-matched controls were recruited. Corneal biomechanical parameters of both groups were measured by CorVis ST and were compared between groups. Potential associations between corneal biomechanical parameters and severity of lens dislocation were also investigated. RESULTS Lower applanation 1 velocity (A1V) (0.13 ± 0.004 vs. 0.15 ± 0.003, P = 0.016), shorter applanation 2 time (A2T)(22.64 ± 0.11 vs. 22.94 ± 0.11, P = 0.013), longer peak distance (PD) (5.03 ± 0.07 vs. 4.81 ± 0.05, P = 0.008), longer radius (R) of highest concavity (7.44 ± 0.16 vs. 6.93 ± 0.14, P = 0.012), greater Ambrosio relational thickness horizontal (ARTh) (603 ± 20 vs. 498 ± 12, P < 0.001), and integrated radius (IR) (8.32 ± 0.25 vs. 8.95 ± 0.21, P = 0.033) were detected among Marfan eyes compared with controls (all P < 0.05). Marfan individuals with more severe lens dislocation tended to have increased stiffness parameter as longer A1T, slower A1V, shorter A2T, slower application 2 velocity (A2V), smaller PD and smaller Distance Amplitude (DA) (P < 0.05). CONCLUSION Marfan patients were detected to have increased corneal stiffness compared with normal subjects. Corneal biomechanical parameters were significantly associated with the severity of lens dislocation in Marfan patients.
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Affiliation(s)
- Guangming Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Minjie Zou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Longhui Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Zhenzhen Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Charlotte Young
- Albany Medical College, 49 New Scotland Ave, Albany, NY, USA
| | - Haotian Qi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Danying Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China.
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Mishra D, Gade S, Glover K, Sheshala R, Singh TRR. Vitreous Humor: Composition, Characteristics and Implication on Intravitreal Drug Delivery. Curr Eye Res 2023; 48:208-218. [PMID: 36036478 DOI: 10.1080/02713683.2022.2119254] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose: Intravitreal administration of drug molecules is one of the most common routes for treating posterior segment eye diseases. However, the properties of vitreous humour changes with the time. A number of ocular complications such as liquefaction of the vitreous humour, solidification of the vitreous humour in the central vitreous cavity and detachment of the limiting membrane due to the shrinking of vitreous humour are some of the factors that can drastically affect the efficacy of therapeutics delivered via intravitreal route. Although significant research has been conducted for studying the properties of vitreous humour and its changes during the ageing process, there have been limited work to understand the effect of these changes on therapeutic efficacy of intravitreal drug delivery systems. Therefore, in this review we discussed both the coomposition and characteristics of the vitreous humour, and their subsequent influence on intravitreal drug delivery.Methods: Articles were searched on Scopus, PubMed and Web of Science up to March 2022.Results: In this review, we discussed the biological composition and biomechanical properties of vitreous humour, methods to study the properties of vitreous humour and the changes in these properties and their relevance in ocular drug delivery field, with the aim to provide a useful insight into these aspects which can aid the process of development of novel intravitreal drug delivery systems.Conclusions: The composition and characteristics of the vitreous humour, and how these change during natural aging processes, directly influence intravitreal drug delivery. This review therefore highlights the importance of understanding the properties of the vitreous and identifies the need to achieve greater understanding of how changing properties of the vitreous affect the therapeutic efficacy of drugs administered for the treatment of posterior eye diseases.
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Affiliation(s)
- Deepakkumar Mishra
- School of Pharmacy, Medical Biology Centre, Queen's University Belfast, Belfast, UK
| | - Shilpkala Gade
- School of Pharmacy, Medical Biology Centre, Queen's University Belfast, Belfast, UK
| | - Katie Glover
- School of Pharmacy, Medical Biology Centre, Queen's University Belfast, Belfast, UK
| | - Ravi Sheshala
- Faculty of Pharmacy, Research Group of Affinity, Safety and Efficacy Studies (OASES), Universiti Teknologi MARA Selangor, Kuala Selangor, Malaysia
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3
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Carstens N, Goolam S, Hulley M, Brandenburg JT, Ramsay M, Williams SEI. Exome-based mutation screening in South African children with primary congenital glaucoma. Eye (Lond) 2023; 37:362-368. [PMID: 35094026 PMCID: PMC9873788 DOI: 10.1038/s41433-022-01941-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 01/03/2022] [Accepted: 01/14/2022] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVES To identify pathogenic variants in a cohort of 23 black South African children with sporadic primary congenital glaucoma (PCG) using an exome-based approach. METHODS Children with PCG were recruited from two Paediatric Ophthalmology Clinics in Johannesburg, South Africa. Whole exome sequencing was performed on genomic DNA. Of the 23 children, 19 were male and 19 had bilateral PCG. A variant prioritization strategy was employed whereby variants in known PCG genes (CYP1B1, LTBP2 and TEK) were evaluated first, followed by the identification of putative disease-causing variants in other genes related to eye diseases and phenotypes. RESULTS Validated pathogenic variants in the CYP1B1 gene (c.1169 G>A; p.Arg390His) and TEK gene (c.922 G>A; p.Gly308Arg) were identified in one child each. No LTBP2 mutations were identified in this cohort. In silico predictions identified potentially damaging rare variants in genes previously associated with eye development phenotypes or glaucoma in a further 12 children. CONCLUSIONS This study demonstrates the value of whole exome sequencing in identifying disease-causing variants in African children with PCG. It is the first report of a TEK disease-causing variant in an African PCG patient. Potential causative variants detected in PCG candidate genes warrant further investigation.
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Affiliation(s)
- Nadia Carstens
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Saadiah Goolam
- Division of Ophthalmology, Department of Neurosciences, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michaella Hulley
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Jean-Tristan Brandenburg
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michele Ramsay
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Susan Eileen Isabella Williams
- Division of Ophthalmology, Department of Neurosciences, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
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Darian-Smith E, Safran SG, Coroneo MT. Zonular and capsular bag disorders: a hypothetical perspective based on recent pathophysiological insights. J Cataract Refract Surg 2023; 49:207-212. [PMID: 36700888 DOI: 10.1097/j.jcrs.0000000000001098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/13/2022] [Indexed: 01/27/2023]
Abstract
The purpose of this article was to look at the pathophysiology behind and devise a classification system for the causes of zonular apparatus-capsular bag (ZACB) insufficiency. Also discussed is dystrophic bag syndrome, including clinical cases and addressing where it lies on the ZACB spectrum. There has been interest in the emergence of in-the-bag intraocular lens (IOL) subluxation, the prevalence of which is increasing. There has also been a recent report of dead bag syndrome, which the authors believe is part of the same disease spectrum. The authors put these phenomena into perspective and provide a classification system based on the possible causes of what they have termed ZACB insufficiency. The basic aspects of capsular bag-IOL ocular pathophysiology are summarized with a focus on functional aspects and the consequences for IOL fastening. Within this framework, dystrophic bag syndrome is a form of primary capsular ZACB insufficiency. The contribution of factors such as intraocular drugs may suggest a reconsideration of agents used and their mode of application.
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Affiliation(s)
- Erica Darian-Smith
- From the Department of Ophthalmology, Prince of Wales Hospital at University of New South Wales, Sydney, Australia (Darian-Smith, Safran, Coroneo); Sydney University Medical School, Sydney, Australia (Darian-Smith); Capital Health System, New Jersey Surgery Centre, Pennington, New Jersey
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DeDreu J, Le PM, Menko AS. The ciliary zonules provide a pathway for immune cells to populate the avascular lens during eye development. Exp Biol Med (Maywood) 2022; 247:2251-2273. [PMID: 36633170 PMCID: PMC9899985 DOI: 10.1177/15353702221140411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/20/2022] [Indexed: 01/13/2023] Open
Abstract
The eye is an immune-privileged site, with both vasculature and lymphatics absent from the central light path. Unique adaptations have made it possible for immune cells to be recruited to this region of the eye in response to ocular injuries and pathogenic insults. The induction of such immune responses is typically activated by tissue resident immune cells, considered the sentinels of the immune system. We discovered that, despite the absence of an embedded vasculature, the embryonic lens becomes populated by resident immune cells. The paths by which they travel to the lens during development were not known. However, our previous studies show that in response to corneal wounding immune cells travel to the lens from the vascular-rich ciliary body across the zonules that link these two tissues. We now examined whether the zonule fibers provide a path for immune cells to the embryonic lens, and the zonule-associated matrix molecules that could promote immune cell migration. The vitreous also was examined as a potential source of lens resident immune cells. This matrix-rich site in the posterior of the eye harbors hyalocytes, an immune cell type with macrophage-like properties. We found that both the zonules and the vitreous of the embryonic eye contained fibrillin-2-based networks and that migration-promoting matrix proteins like fibronectin and tenascin-C were linked to these fibrils. Immune cells were seen emerging from the ciliary body, migrating along the ciliary zonules to the lens, and invading through the lens capsule at its equator. This is just adjacent to where immune cells take up residence in the embryonic lens. In contrast, the immune cells of the vitreous were not detected in the region of the lens. These results strongly suggest that the ciliary zonules are a primary path of immune cell delivery to the developing lens.
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Affiliation(s)
- JodiRae DeDreu
- Department of Pathology and Genomic
Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia,
PA 19107, USA
| | - Phuong M Le
- Department of Pathology and Genomic
Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia,
PA 19107, USA
| | - A. Sue Menko
- Department of Pathology and Genomic
Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia,
PA 19107, USA
- Department of Ophthalmology, Sidney
Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107,
USA
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Stanciu PE, O'Regan A, Cosgrave E. Late onset sclerotomy dehiscence in a patient with Marfan syndrome presenting as recurrent episodes of raised intraocular pressure. BMJ Case Rep 2022; 15:15/8/e249990. [PMID: 36041776 PMCID: PMC9438104 DOI: 10.1136/bcr-2022-249990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A man in his 50s presented to the eye emergency department on three separate occasions complaining of blurred vision and discomfort in the left eye. He had a history of Marfan syndrome and had undergone bilateral 20-gauge (G) pars plana vitrectomy and lensectomy 20 years prior for ectopia lentis. On examination he had epithelial corneal oedema, raised intraocular pressure >40 mm Hg and conjunctival chemosis, which later appeared as a bleb-like conjunctival elevation. Acute treatment with oral acetazolamide and topical ocular hypotensive agents produced a marked reduction in intraocular pressure to 2–4 mm Hg. A presumed diagnosis of a leaking scleral wound was made. He underwent scleral exploration under general anaesthesia and a leaking sclerotomy was uncovered. The defect was repaired successfully using a scleral patch graft. Late dehiscence of a sclerotomy has been reported rarely in patients with Marfan syndrome. This is the first reported case to present atypically with intermittent episodes of raised intraocular pressure rather than with hypotony.
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Affiliation(s)
| | - Amy O'Regan
- Ophthalmology department, University Hospital Waterford, Waterford, Ireland
| | - Edel Cosgrave
- Ophthalmology department, University Hospital Waterford, Waterford, Ireland
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Rezar-Dreindl S, Eibenberger K, Told R, Unterluggauer V, Sacu S, Schmidt-Erfurth U, Stifter E. Microvascular retinal changes in patients with Marfan syndrome. Curr Eye Res 2022; 47:1186-1192. [PMID: 35416099 DOI: 10.1080/02713683.2022.2066698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Purpose. To determine microvascular changes in patients with genetically proven Marfan syndrome.Methods. In a cross-sectional study, 32 eyes of 16 patients with genetically proven Marfan syndrome were evaluated using swept-source optical coherence tomography angiography (SS-OCTA). Patients were analyzed regarding lens status and systemic vascular disease. The foveal avascular zone (FAZ) and vessel density (VD) of the superficial and deep vascular plexus and central retinal thickness (CRT) were evaluated on SS-OCTA.Results. 44/56% patients presented without/with subluxation of the lens. 69% of patients had presence of mitral valve insufficiency, aortic dilatation or aneurysm of the aortic root. In patients with Marfan syndrome the mean area of the FAZ was 0.2 ± 0.1mm and the average VD of the superficial/deep vascular plexus was 36 ± 5%/22 ± 7%. In patients with subluxation of the lens FAZ area and perimeter were larger when compared to patients without subluxation of the lens (0.18 ± 0.08/0.28 ± 0.10 mm and 1.7 ± 0.4/2.3 ± 0.8; p = 0.02). VD of the superficial vascular plexus was reduced in patients with subluxation of the lens (on average 39 ± 3/33 ± 8; p = 0.01) together with an increased CRT in the inner segments of the ETDRS grid when compared to patients without subluxation of the lens. In patients with systemic vascular disease a larger FAZ area (0.19 ± 0.06/0.25 ± 0.1mm; p = 0.04) and reduced VD of the superficial vascular plexus in the central ETDRS grid (28 ± 7/21 ± 6; p = 0.02) was observed in comparison to patients without systemic vascular changes.Conclusions. In patients with Marfan syndrome SS-OCTA imaging revealed microvascular differences in patients with lens subluxation and/or systemic vascular disease.
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Affiliation(s)
- Sandra Rezar-Dreindl
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Katharina Eibenberger
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Reinhard Told
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Veronika Unterluggauer
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Stefan Sacu
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Eva Stifter
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
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Safran SG, Darian-Smith E, Coroneo MT. Intraocular lens explantation following cataract surgery: Indications, techniques, and video demonstrations. Eur J Ophthalmol 2021; 32:1333-1339. [PMID: 34407662 DOI: 10.1177/11206721211039686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
As techniques for modern cataract surgery have expanded and premium intraocular lens (IOL) use is now widespread, patient expectations are high. The need for IOL explantation, whilst still low, remains an ongoing issue. Intraocular lens explantation can be challenging for a number of reasons and as such we have introduced an additional technique to add to the surgeon's repertoire. Bimanual haptic stripping of fibrosis at the specific area where the haptic is adherent to the capsular bag is an effective strategy to aid in dissection of haptics without compromising the capsule or zonules. Given the challenges associated with IOL explantation, newly designed IOLs need to avoid these "sticking points" at which the IOLs interact with the fibrosed capsule. Techniques we have evolved and which are described below should assist anterior segment surgeons to facilitate IOL removal in an efficient and safe way.
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Affiliation(s)
- Steven G Safran
- Capital Health System, New Jersey Surgery Center, Hamilton Township, NJ, USA
| | - Erica Darian-Smith
- Department of Ophthalmology, University of New South Wales at Prince of Wales Hospital, Sydney, NSW, Australia.,Sydney University Medical School, Sydney, NSW, Australia
| | - Minas T Coroneo
- Department of Ophthalmology, University of New South Wales at Prince of Wales Hospital, Sydney, NSW, Australia
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Investigation of fibrillin microfibrils in the canine cruciate ligament in dogs with different predispositions to ligament rupture. Res Vet Sci 2020; 133:53-58. [PMID: 32937286 DOI: 10.1016/j.rvsc.2020.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 06/03/2020] [Accepted: 09/08/2020] [Indexed: 11/20/2022]
Abstract
Cranial cruciate ligament disease (CCLD) is the most common cause of pelvic limb lameness in dogs but its precise aetiopathogenesis is uncertain. Fibrillin microfibrils (FM) are complex macro-molecular assemblies found in many tissues including ligaments, where they are thought to play an important mechanical role. We hypothesised that FM ultrastructural variation correlates with the differing predisposition of canine breeds to CCLD. Non-diseased cranial and caudal cruciate ligaments (CCLs and CaCLs) were obtained from Greyhound (GH) and Staffordshire Bull Terrier (SBT) cadavers. Fibrillin microfibrils were extracted from the ligaments by bacterial collagenase digestion, purified by size-exclusion chromatography and subsequently visualized by atomic force microscopy (AFM). With AFM, FMs have a characteristic beads-on-a-string appearance. For each FM, periodicity (bead-bead distance) and length (number of beads/FM) was measured. Fibrillin microfibril length was found to be similar for GH and SBT, with non-significant inter-breed and inter-ligament differences. Fibrillin microfibril periodicity varied when comparing GH and SBT for CCL (GH 60.2 ± 1.4 nm; SBT 56.2 ± 0.8 nm) and CaCL (GH 55.5 ± 1.6 nm; SBT 61.2 ± 1.2 nm). A significant difference was found in the periodicity distribution when comparing CCL for both breeds (P < 0.00001), further, intra-breed differences in CCL vs CaCL were statistically significant within both breeds (P < 0.00001). The breed at low risk of CCLD exhibited a periodicity profile which may be suggestive of a repair and remodelling within the CCL.
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Langton AK, Tsoureli-Nikita E, Merrick H, Zhao X, Antoniou C, Stratigos A, Akhtar R, Derby B, Sherratt MJ, Watson RE, Griffiths CE. The systemic influence of chronic smoking on skin structure and mechanical function. J Pathol 2020; 251:420-428. [PMID: 32472631 DOI: 10.1002/path.5476] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/15/2020] [Accepted: 05/20/2020] [Indexed: 12/21/2022]
Abstract
One of the major functions of human skin is to provide protection from the environment. Although we cannot entirely avoid, for example, sun exposure, it is likely that exposure to other environmental factors could affect cutaneous function. A number of studies have identified smoking as one such factor that leads to both facial wrinkle formation and a decline in skin function. In addition to the direct physical effects of tobacco smoke on skin, its inhalation has additional profound systemic effects for the smoker. The adverse effects on the respiratory and cardiovascular systems from smoking are well known. Central to the pathological changes associated with smoking is the elastic fibre, a key component of the extracellular matrices of lungs. In this study we examined the systemic effect of chronic smoking (>40 cigarettes/day; >5 years) on the histology of the cutaneous elastic fibre system, the nanostructure and mechanics of one of its key components, the fibrillin-rich microfibril, and the micromechanical stiffness of the dermis and epidermis. We show that photoprotected skin of chronic smokers exhibits significant remodelling of the elastic fibre network (both elastin and fibrillin-rich microfibrils) as compared to the skin of age- and sex-matched non-smokers. This remodelling is not associated with increased gelatinase activity (as identified by in situ zymography). Histological remodelling is accompanied by significant ultrastructural changes to extracted fibrillin-rich microfibrils. Finally, using scanning acoustic microscopy, we demonstrated that chronic smoking significantly increases the stiffness of both the dermis and the epidermis. Taken together, these data suggest an unappreciated systemic effect of chronic inhalation of tobacco smoke on the cutaneous elastic fibre network. Such changes may in part underlie the skin wrinkling and loss of skin elasticity associated with smoking. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Abigail K Langton
- Centre for Dermatology Research, The University of Manchester & Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.,NIHR Manchester Biomedical Research Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Evridiki Tsoureli-Nikita
- First Department of Dermatology, Andreas Syggros Hospital of Cutaneous & Venereal Diseases, Athens University Medical School, Athens, Greece
| | - Holly Merrick
- Centre for Dermatology Research, The University of Manchester & Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Xuegen Zhao
- School of Materials, The University of Manchester, Manchester, UK
| | - Christina Antoniou
- First Department of Dermatology, Andreas Syggros Hospital of Cutaneous & Venereal Diseases, Athens University Medical School, Athens, Greece
| | - Alexander Stratigos
- First Department of Dermatology, Andreas Syggros Hospital of Cutaneous & Venereal Diseases, Athens University Medical School, Athens, Greece
| | - Riaz Akhtar
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, UK
| | - Brian Derby
- School of Materials, The University of Manchester, Manchester, UK
| | - Michael J Sherratt
- Division of Cell Matrix Biology & Regenerative Medicine, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK
| | - Rachel Eb Watson
- Centre for Dermatology Research, The University of Manchester & Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.,NIHR Manchester Biomedical Research Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Christopher Em Griffiths
- Centre for Dermatology Research, The University of Manchester & Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.,NIHR Manchester Biomedical Research Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
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Zech JC, Putoux A, Decullier E, Fargeton AE, Edery P, Plauchu H, Dupuis-Girod S. Classifying Ectopia Lentis in Marfan Syndrome into Five Grades of Increasing Severity. J Clin Med 2020; 9:jcm9030721. [PMID: 32155956 PMCID: PMC7141252 DOI: 10.3390/jcm9030721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/12/2020] [Accepted: 02/27/2020] [Indexed: 11/16/2022] Open
Abstract
Purpose: To describe a five-grade classification of ectopia lentis in Marfan syndrome (MFS) and to evaluate the positive predictive value of the early grades of ectopia lentis. Methods: We prospectively included MFS patients and their healthy relatives. The anterior segment examination was classified into grades 0 to 5, and we studied the sensitivity, specificity, and positive predictive value of ectopia lentis in this classification. Results: Seventy-four MFS patients and thirty-six healthy controls were examined. In the MFS group, grades 1, 2, 3, and 4 were present in 15, 24, 17, and 7 patients, respectively, whereas 11 patients in this group did not present ectopia lentis. In the control group, grades 0 and 1 were observed in 30 and 6 individuals, respectively. Sensitivity to ectopia lentis of at least grade 2 was 64.9%, with 100% specificity, whereas sensitivity to ectopia lentis of at least grade 1 was 85.1%, with 83.3% specificity. The positive predictive value of ectopia lentis that was greater than or equal to grade 2 was 100%, whereas that of ectopia lentis greater than or equal to grade 1 was 91.3%. Conclusions: High positive predictive values s were found to be associated with grades 2 and higher of the five-grade classification of ectopia lentis. This classification should help to harmonize clinical practices for this major feature of MFS.
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Affiliation(s)
| | - Audrey Putoux
- Service de Génétique, Unité de Génétique Clinique, Centre Labellisé Anomalies du Développement, Hospices Civils de Lyon, 69500 Bron, France; (A.P.); (P.E.)
- Centre de Recherche en Neurosciences de Lyon, Equipe GENDEV, INSERM U1028, UMR CNRS 5292, Université Claude Bernard Lyon 1, 69500 Bron, France
| | - Evelyne Decullier
- Unité de Recherche Clinique, Pôle Santé Publique, Hospices Civils de Lyon, 69003 Lyon, France;
| | - Anne-Emmanuelle Fargeton
- Service de Génétique, Unité de Génétique Clinique, Centre de Compétence Syndrome de Marfan et Apparentés, Hospices Civils de Lyon, 69500 Bron, France; (H.P.); (S.D.-G.)
- Correspondence:
| | - Patrick Edery
- Service de Génétique, Unité de Génétique Clinique, Centre Labellisé Anomalies du Développement, Hospices Civils de Lyon, 69500 Bron, France; (A.P.); (P.E.)
- Centre de Recherche en Neurosciences de Lyon, Equipe GENDEV, INSERM U1028, UMR CNRS 5292, Université Claude Bernard Lyon 1, 69500 Bron, France
| | - Henri Plauchu
- Service de Génétique, Unité de Génétique Clinique, Centre de Compétence Syndrome de Marfan et Apparentés, Hospices Civils de Lyon, 69500 Bron, France; (H.P.); (S.D.-G.)
| | - Sophie Dupuis-Girod
- Service de Génétique, Unité de Génétique Clinique, Centre de Compétence Syndrome de Marfan et Apparentés, Hospices Civils de Lyon, 69500 Bron, France; (H.P.); (S.D.-G.)
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Proteomics reveals a set of highly enriched proteins in epiretinal membrane compared with inner limiting membrane. Exp Eye Res 2019; 186:107722. [PMID: 31302158 DOI: 10.1016/j.exer.2019.107722] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 07/03/2019] [Accepted: 07/09/2019] [Indexed: 12/28/2022]
Abstract
Few data exist regarding the protein composition of idiopathic epiretinal membrane (iERM). In the present study we compared the proteome of epiretinal membrane of iERM with the proteome of the inner limiting membrane (ILM) of idiopathic macular hole (iMH). Twelve epiretinal membrane samples were obtained from patients with iERM undergoing therapeutic vitrectomy. Twelve ILM samples from patients with iMH were used as controls. Proteomic analysis was conducted with discovery-based label-free quantitative nano-liquid chromatography - tandem mass spectrometry (LFQ nLC-MS/MS). Verification of results was performed with targeted MS using selected reaction monitoring on a different set of samples. Discovery data were searched against the Uniprot Homo sapiens protein database using MaxQuant Software. Identified proteins were filtered with Perseus software. Bioinformatic analysis of the differences in protein expression between epiretinal membrane from iERM and ILM from iMH was performed using STRING. A total of 2,183 different proteins were identified. 357 proteins were found to be present in all samples. The protein profile of iERM was highly different from iMH with 62 proteins found at significantly higher levels in iERM. The proteins upregulated more than 10-fold in iERM were: fibrillin-1, tenascin, prolargin, biglycan, opticin, collagen alpha-1(II) chain, protein-glutamine gamma-glutamyltransferase 2, fibronectin, filamin-A, collagen alpha-2(IX) chain, spectrin alpha chain, transforming growth factor beta induced protein ig-h3, dihydropyrimidinase - related protein 3, endoplasmin and glutamate dehydrogenase 1. Proteins with high level in iERM consisted of proteins that especially localized to the actin cytoskeleton, the extracellular matrix and the mitochondrion. Analysis of all proteins indicated that the disease process in iERM at least in part can be characterized as skin formation with perturbation of nucleotide metabolism. Our study identified proteins that have not earlier been associated with iERM. Fifteen proteins are found at very high concentration, 10-fold or more, and amongst these four proteins, fibrillin-1, tenascin, prolargin and biglycan were found at more than a 100-fold higher content compared to ILM of iMH. These proteins may be potential therapeutic targets. Data are available via ProteomeXchange with identifier PXD014286.
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Eckersley A, Mellody KT, Pilkington S, Griffiths CEM, Watson REB, O'Cualain R, Baldock C, Knight D, Sherratt MJ. Structural and compositional diversity of fibrillin microfibrils in human tissues. J Biol Chem 2018; 293:5117-5133. [PMID: 29453284 PMCID: PMC5892578 DOI: 10.1074/jbc.ra117.001483] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/07/2018] [Indexed: 12/11/2022] Open
Abstract
Elastic fibers comprising fibrillin microfibrils and elastin are present in many tissues, including the skin, lungs, and arteries, where they confer elasticity and resilience. Although fibrillin microfibrils play distinct and tissue-specific functional roles, it is unclear whether their ultrastructure and composition differ between elastin-rich (skin) and elastin-poor (ciliary body and zonule) organs or after in vitro synthesis by cultured cells. Here, we used atomic force microscopy, which revealed that the bead morphology of fibrillin microfibrils isolated from the human eye differs from those isolated from the skin. Using newly developed pre-MS preparation methods and LC-MS/MS, we detected tissue-specific regions of the fibrillin-1 primary structure that were differentially susceptible to proteolytic extraction. Comparing tissue- and culture-derived microfibrils, we found that dermis- and dermal fibroblast–derived fibrillin microfibrils differ in both bead morphology and periodicity and also exhibit regional differences in fibrillin-1 proteolytic susceptibility. In contrast, collagen VI microfibrils from the same dermal or fibroblast samples were invariant in ultrastructure (periodicity) and protease susceptibility. Finally, we observed that skin- and eye-derived microfibril suspensions were enriched in elastic fiber– and basement membrane–associated proteins, respectively. LC-MS/MS also identified proteins (such as calreticulin and protein-disulfide isomerase) that are potentially fundamental to fibrillin microfibril biology, regardless of their tissue source. Fibrillin microfibrils synthesized in cell culture lacked some of these key proteins (MFAP2 and -4 and fibrillin-2). These results showcase the structural diversity of these key extracellular matrix assemblies, which may relate to their distinct roles in the tissues where they reside.
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Affiliation(s)
| | - Kieran T Mellody
- From the Division of Cell Matrix Biology and Regenerative Medicine
| | | | - Christopher E M Griffiths
- the Division of Musculoskeletal and Dermatological Sciences.,the NIHR Manchester Biomedical Research Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | - Rachel E B Watson
- the Division of Musculoskeletal and Dermatological Sciences.,the NIHR Manchester Biomedical Research Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9PT, United Kingdom
| | | | - Clair Baldock
- From the Division of Cell Matrix Biology and Regenerative Medicine.,the Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom and
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White TL, Lewis PN, Young RD, Kitazawa K, Inatomi T, Kinoshita S, Meek KM. Elastic microfibril distribution in the cornea: Differences between normal and keratoconic stroma. Exp Eye Res 2017; 159:40-48. [PMID: 28315339 PMCID: PMC5451143 DOI: 10.1016/j.exer.2017.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/15/2017] [Accepted: 03/12/2017] [Indexed: 11/28/2022]
Abstract
The optical and biomechanical properties of the cornea are largely governed by the collagen-rich stroma, a layer that represents approximately 90% of the total thickness. Within the stroma, the specific arrangement of superimposed lamellae provides the tissue with tensile strength, whilst the spatial arrangement of individual collagen fibrils within the lamellae confers transparency. In keratoconus, this precise stromal arrangement is lost, resulting in ectasia and visual impairment. In the normal cornea, we previously characterised the three-dimensional arrangement of an elastic fiber network spanning the posterior stroma from limbus-to-limbus. In the peripheral cornea/limbus there are elastin-containing sheets or broad fibers, most of which become microfibril bundles (MBs) with little or no elastin component when reaching the central cornea. The purpose of the current study was to compare this network with the elastic fiber distribution in post-surgical keratoconic corneal buttons, using serial block face scanning electron microscopy and transmission electron microscopy. We have demonstrated that the MB distribution is very different in keratoconus. MBs are absent from a region of stroma anterior to Descemet's membrane, an area that is densely populated in normal cornea, whilst being concentrated below the epithelium, an area in which they are absent in normal cornea. We contend that these latter microfibrils are produced as a biomechanical response to provide additional strength to the anterior stroma in order to prevent tissue rupture at the apex of the cone. A lack of MBs anterior to Descemet's membrane in keratoconus would alter the biomechanical properties of the tissue, potentially contributing to the pathogenesis of the disease.
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Affiliation(s)
- Tomas L White
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Philip N Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Robert D Young
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
| | - Koji Kitazawa
- Department of Ophthalmology, Kyoto Prefectural University, Kyoto, Japan; Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University, Kyoto, Japan
| | - Tsutomu Inatomi
- Department of Ophthalmology, Kyoto Prefectural University, Kyoto, Japan
| | - Shigeru Kinoshita
- Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University, Kyoto, Japan
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
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A potential role for endogenous proteins as sacrificial sunscreens and antioxidants in human tissues. Redox Biol 2015; 5:101-113. [PMID: 25911998 PMCID: PMC4412910 DOI: 10.1016/j.redox.2015.04.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 01/19/2023] Open
Abstract
Excessive ultraviolet radiation (UVR) exposure of the skin is associated with adverse clinical outcomes. Although both exogenous sunscreens and endogenous tissue components (including melanins and tryptophan-derived compounds) reduce UVR penetration, the role of endogenous proteins in absorbing environmental UV wavelengths is poorly defined. Having previously demonstrated that proteins which are rich in UVR-absorbing amino acid residues are readily degraded by broadband UVB-radiation (containing UVA, UVB and UVC wavelengths) here we hypothesised that UV chromophore (Cys, Trp and Tyr) content can predict the susceptibility of structural proteins in skin and the eye to damage by physiologically relevant doses (up to 15.4 J/cm2) of solar UVR (95% UVA, 5% UVB). We show that: i) purified suspensions of UV-chromophore-rich fibronectin dimers, fibrillin microfibrils and β- and γ-lens crystallins undergo solar simulated radiation (SSR)-induced aggregation and/or decomposition and ii) exposure to identical doses of SSR has minimal effect on the size or ultrastructure of UV chromophore-poor tropoelastin, collagen I, collagen VI microfibrils and α-crystallin. If UV chromophore content is a factor in determining protein stability in vivo, we would expect that the tissue distribution of Cys, Trp and Tyr-rich proteins would correlate with regional UVR exposure. From bioinformatic analysis of 244 key structural proteins we identified several biochemically distinct, yet UV chromophore-rich, protein families. The majority of these putative UV-absorbing proteins (including the late cornified envelope proteins, keratin associated proteins, elastic fibre-associated components and β- and γ-crystallins) are localised and/or particularly abundant in tissues that are exposed to the highest doses of environmental UVR, specifically the stratum corneum, hair, papillary dermis and lens. We therefore propose that UV chromophore-rich proteins are localised in regions of high UVR exposure as a consequence of an evolutionary pressure to express sacrificial protein sunscreens which reduce UVR penetration and hence mitigate tissue damage. Major structural proteins such as collagen I and tropoelastin are UVA-resistant. In contrast, proteins which are rich in Cys, Trp and Tyr residues are UV-susceptible. These proteins are concentrated in UV exposed tissues. UV-chromophore (Cys, Trp, Tyr)-rich proteins may act as endogenous sunscreens.
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Localized micro- and nano-scale remodelling in the diabetic aorta. Acta Biomater 2014; 10:4843-4851. [PMID: 25014552 PMCID: PMC4199142 DOI: 10.1016/j.actbio.2014.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/22/2014] [Accepted: 07/01/2014] [Indexed: 11/20/2022]
Abstract
Diabetes is strongly associated with cardiovascular disease, but the mechanisms, structural and biomechanical consequences of aberrant blood vessel remodelling remain poorly defined. Using an experimental (streptozotocin, STZ) rat model of diabetes, we hypothesized that diabetes enhances extracellular protease activity in the aorta and induces morphological, compositional and localized micromechanical tissue remodelling. We found that the medial aortic layer underwent significant thickening in diabetic animals but without significant changes in collagen or elastin (abundance). Scanning acoustic microscopy demonstrated that such tissue remodelling was associated with a significant decrease in acoustic wave speed (an indicator of reduced material stiffness) in the inter-lamellar spaces of the vessel wall. This index of decreased stiffness was also linked to increased extracellular protease activity (assessed by semi-quantitative in situ gelatin zymography). Such a proteolytically active environment may affect the macromolecular structure of long-lived extracellular matrix molecules. To test this hypothesis, we also characterized the effects of diabetes on the ultrastructure of an important elastic fibre component: the fibrillin microfibril. Using size exclusion chromatography and atomic force microscopy, we isolated and imaged microfibrils from both healthy and diabetic aortas. Microfibrils derived from diabetic tissues were fragmented, morphologically disrupted and weakened (as assessed following molecular combing). These structural and functional abnormalities were not replicated by in vitro glycation. Our data suggest that proteolysis may be a key driver of localized mechanical change in the inter-lamellar space of diabetic rat aortas and that structural proteins (such as fibrillin microfbrils) may be biomarkers of diabetes induced damage.
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Inoue T, Ohbayashi T, Fujikawa Y, Yoshida H, Akama TO, Noda K, Horiguchi M, Kameyama K, Hata Y, Takahashi K, Kusumoto K, Nakamura T. Latent TGF-β binding protein-2 is essential for the development of ciliary zonule microfibrils. Hum Mol Genet 2014; 23:5672-82. [PMID: 24908666 DOI: 10.1093/hmg/ddu283] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Latent TGF-β-binding protein-2 (LTBP-2) is an extracellular matrix protein associated with microfibrils. Homozygous mutations in LTBP2 have been found in humans with genetic eye diseases such as congenital glaucoma and microspherophakia, indicating a critical role of the protein in eye development, although the function of LTBP-2 in vivo has not been well understood. In this study, we explore the in vivo function of LTBP-2 by generating Ltbp2(-/-) mice. Ltbp2(-/-) mice survived to adulthood but developed lens luxation caused by compromised ciliary zonule formation without a typical phenotype related to glaucoma, suggesting that LTBP-2 deficiency primarily causes lens dislocation but not glaucoma. The suppression of LTBP2 expression in cultured human ciliary epithelial cells by siRNA disrupted the formation of the microfibril meshwork by the cells. Supplementation of recombinant LTBP-2 in culture medium not only rescued the microfibril meshwork formation in LTBP2-suppressed ciliary epithelial cells but also restored unfragmented and bundled ciliary zonules in Ltbp2(-/-) mouse eyes under organ culture. Although several reported human mutant LTBP-2 proteins retain normal domain structure and keep the fibrillin-1-binding site intact, none of these mutant proteins were secreted from their producing cells, suggesting secretion arrest occurred to the LTBP-2 mutants owing to conformational alteration. The findings of this study suggest that LTBP-2 is an essential component for the formation of microfibril bundles in ciliary zonules.
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Affiliation(s)
- Tadashi Inoue
- Department of Pharmacology, Department of Plastic and Reconstructive Surgery
| | - Tetsuya Ohbayashi
- Division of Laboratory Animal Science, Research Center for Bioscience and Technology and
| | | | - Hideyuki Yoshida
- Department of Pharmacology, Department of Ophthalmology, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Tomoya O Akama
- Department of Pharmacology, Tumor Microenvironment Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Kazuo Noda
- Department of Pharmacology, Department of Plastic and Reconstructive Surgery, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan and
| | - Masahito Horiguchi
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Katsuro Kameyama
- Division of Integrative Bioscience, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Sciences, Yonago, Tottori 683-8503, Japan
| | - Yoshio Hata
- Division of Integrative Bioscience, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Sciences, Yonago, Tottori 683-8503, Japan
| | - Kanji Takahashi
- Department of Ophthalmology, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
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Cankaya AB, Teberik P, Acaroglu G. Alterations in anterior chamber depth in primary open-angle glaucoma patients during latanoprost therapy. Acta Ophthalmol 2011; 89:274-7. [PMID: 19860780 DOI: 10.1111/j.1755-3768.2009.01683.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE The aim of this study was to evaluate changes in the anterior chamber depth (ACD) in primary open-angle glaucoma (POAG) patients during latanoprost therapy. METHODS We carried out a prospective study in which we enrolled 66 newly diagnosed POAG patients treated with latanoprost 0.005% (group 1) and 50 ocular hypertensive and ⁄ or glaucoma suspect cases who were given no therapy (group 2 [control]). Measurements of the ACD were performed by A-scan ultrasonography before and after cycloplegia at baseline and at 3 months of latanoprost therapy. Differences in ACD and their correlations with the ocular hypotensive effect of the agent as well as the clinical significance of changes in ACD were analysed using Student’s t-test and Pearson’s correlation coefficient. Statistical significance was set at p < 0.05. RESULTS Mean baseline ACD was 3.13 ± 0.35 mm (range 2.45–3.84 mm) in group 1 and 3.14 ± 0.36 mm (range 2.54–3.80 mm) in group 2 (p = 0.89). At 1 hour after instillation of cyclopentolate 1%, mean ACD in groups 1 and 2 was 3.18 ± 0.38 mm (range 2.45–3.92 mm) and 3.19 ± 0.37 mm (range 2.56–3.91 mm), respectively (p = 0.91). After 3 months of treatment, mean ACD in group 1 both without (3.05 ± 0.36 mm, range 2.14–3.76 mm) and with (3.09 ± 0.4 mm, range 2.20–3.96 mm) cycloplegia was significantly reduced compared with baseline values (p < 0.001 for both). However, there was no significant difference between mean ACD at baseline and that at month 3 in group 2. No correlation was demonstrated between the changes in ACD and the ocular hypotensive effect of latanoprost (p = 0.96, r = – 0.006). There were no changes in refractive status or visual acuity. CONCLUSIONS The overall results seem to suggest that latanoprost decreases mean ACD in patients with POAG. The clinical significance of this effect is uncertain.
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Hann CR, Fautsch MP. The elastin fiber system between and adjacent to collector channels in the human juxtacanalicular tissue. Invest Ophthalmol Vis Sci 2011; 52:45-50. [PMID: 20720231 DOI: 10.1167/iovs.10-5620] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To determine the composition and investigate the elastin fiber system in the juxtacanalicular tissue adjacent to and between collector channel orifices in normal human eyes. METHODS Normal human eyes (71.0 ± 8.6 years; mean ± SD; n = 4) were perfusion fixed at low (10 mm Hg) and high pressure (20 mm Hg) with 3% paraformaldehyde/0.1 M phosphate buffer. Frontal serial sections were cut from paraffin blocks, and regions with and without collector channels were selected. Sections were stained using Weigert's resorcin-fuchsin stain with oxidation. Immunohistochemistry was performed using antibodies against elastin, fibrillin-1, and microfibrillar-associated protein-1/2. RESULTS Elastin, elaunin, and oxytalan fibers were identified within the juxtacanalicular tissue of the inner and outer walls in low- and high-pressure eyes. These fibers were found at collector channel orifices, between collector channels, and within collector channel walls. Fibrillin-1 was located at the base and lateral edges of Schlemm's canal endothelial cells. Microfibrillar-associated protein-1/2 was found with elastin-like fibers at the base of Schlemm's canal endothelium cells, in the juxtacanalicular tissue, and in the uveal region. CONCLUSIONS Elastin, elaunin, oxytalan, and elastin-associated proteins fibrillin-1 and microfibrillar-associated protein-1/2 were identified within the juxtacanalicular tissue of the inner and outer walls and within collector channel walls of human eyes perfused at low and high pressure. No differences in labeling patterns for elastin, elaunin, and oxytalan were found in the juxtacanalicular tissue adjacent to or between collector channel orifices. The elastin fiber system appears to have a significant role in the support and distensibility of the juxtacanalicular region under collector channels.
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Affiliation(s)
- Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA.
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Colitz CMH, Saville WJA, Renner MS, McBain JF, Reidarson TH, Schmitt TL, Nolan EC, Dugan SJ, Knightly F, Rodriguez MM, Mejia-Fava JC, Osborn SD, Clough PL, Collins SP, Osborn BA, Terrell K. Risk factors associated with cataracts and lens luxations in captive pinnipeds in the United States and the Bahamas. J Am Vet Med Assoc 2010; 237:429-36. [PMID: 20707754 DOI: 10.2460/javma.237.4.429] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine risk factors for lens luxation and cataracts in captive pinnipeds in the United States and the Bahamas. DESIGN Cross-sectional study. ANIMALS 111 pinnipeds (99 California sea lions [Zalophus californianus], 10 harbor seals [Phoca vitulina], and 2 walruses [Odobenus rosmarus]) from 9 facilities. PROCEDURES Eyes of each pinniped were examined by a veterinary ophthalmologist for the presence of cataracts or lens luxations and photographed. Information detailing husbandry practices, history, and facilities was collected with a questionnaire, and descriptive statistical analyses were performed for continuous and categorical variables. Odds ratios and associated 95% confidence intervals were estimated from the final model. RESULTS Risk factors for lens luxation, cataracts, or both included age >or= 15 years, history of fighting, history of ocular disease, and insufficient access to shade. CONCLUSIONS AND CLINICAL RELEVANCE Diseases of the lens commonly affect captive pinnipeds. Access to UV-protective shade, early identification and medical management of ocular diseases, and prevention of fighting can limit the frequency or severity of lens-related disease in this population. An extended life span may result from captivity, but this also allows development of pathological changes associated with aging, including cataracts.
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Affiliation(s)
- Carmen M H Colitz
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
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Sherratt MJ, Bayley CP, Reilly SM, Gibbs NK, Griffiths CEM, Watson REB. Low-dose ultraviolet radiation selectively degrades chromophore-rich extracellular matrix components. J Pathol 2010; 222:32-40. [PMID: 20552716 DOI: 10.1002/path.2730] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Photoageing of human skin due to chronic exposure to ultraviolet radiation (UVR) is characterized histologically by extensive remodelling of the dermal elastic fibre system. Whilst enzymatic pathways are thought to play a major role in mediating extracellular matrix (ECM) degeneration in UV-exposed skin, the substrate specificity of UVR-up-regulated and activated matrix metalloproteinases (MMPs) is low. It is unclear, therefore, how such cell-mediated mechanisms alone could be responsible for the reported selective degradation of elastic fibre components such as fibrillin-1 and fibulin-5 during the early stages of photoageing. Here we use atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM) to demonstrate that physiologically attainable doses (20-100 mJ/cm(2)) of direct UV-B radiation can induce profound, dose-dependent, changes in the structure of, and mass distribution within, isolated fibrillin microfibrils. Furthermore, using reducing and native PAGE in combination with AFM, we show that, whilst exposure to low-dose UV-B radiation significantly alters the macromolecular and quaternary structures of both UV chromophore (Cys, His, Phe, Trp and Tyr)-rich fibrillin microfibrils (fibrillin-1, 21.0%) and fibronectin dimers (fibronectin, 12.9%), similar doses have no detectable effect on UV chromophore-poor type I collagen monomers (2.2%). Analysis of the published primary amino acid sequences of 49 dermal ECM components demonstrates that most elastic fibre-associated proteins, but crucially neither elastin nor members of the collagen family, are rich in UV chromophores. We suggest, therefore, that the amino acid composition of elastic fibre-associated proteins [including the fibrillins, fibulins, latent TGFbeta binding proteins (LTBPs) and the lysyl oxidase family of enzymes (LOK/LOXLs)] may predispose them to direct degradation by UVR. As a consequence, this selective acellular photochemical pathway may play an important role in initiating and/or exacerbating cell-mediated ECM remodelling in UVR-exposed skin.
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Affiliation(s)
- Michael J Sherratt
- Regenerative Biomedicine, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.
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Kaul H, Riazuddin SA, Qazi ZA, Nasir IA, Zafar AU, Khan SN, Husnain T, Akram J, Hejtmancik JF, Riazuddin S. Ectopia lentis in a consanguineous pakistani family and a novel locus on chromosome 8q. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2010; 128:1046-9. [PMID: 20697006 PMCID: PMC3398798 DOI: 10.1001/archophthalmol.2010.165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To investigate the genetic basis and molecular characteristics of the isolated form of ectopia lentis. METHODS We ascertained a consanguineous Pakistani family with multiple individuals with ectopia lentis. All affected as well as unaffected members with isolated ectopia lentis underwent detailed ophthalmologic and medical examination. Blood samples were collected and DNA was extracted. A genome-wide scan was completed with 382 polymorphic microsatellite markers, and logarithm of odds (LOD) scores were calculated. RESULTS Maximum 2-point LOD scores of 5.68 and 2.88 at theta = 0 were obtained for markers D8S285 and D8S260, respectively, during the genome-wide scan. Additional microsatellite markers refined the disease locus to a 16.96-cM (14.07-Mb) interval flanked by D8S1737 proximally and D8S1117 distally. CONCLUSIONS We report on a new locus for nonsyndromic autosomal recessive ectopia lentis on chromosome 8q11.23-q13.2 in a consanguineous Pakistani family. Clinical Relevance Identification of genetic loci and genes involved in ectopia lentis will enhance our understanding of the disease at a molecular level, leading to better genetic counseling and family screening and possible future development of better treatment.
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Affiliation(s)
- Haiba Kaul
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
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Wang MC, Lu Y, Baldock C. Fibrillin microfibrils: a key role for the interbead region in elasticity. J Mol Biol 2009; 388:168-79. [PMID: 19268673 DOI: 10.1016/j.jmb.2009.02.062] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 02/26/2009] [Accepted: 02/26/2009] [Indexed: 11/16/2022]
Abstract
Fibrillin microfibrils have essential roles in elastic fiber formation and elastic tissue homeostasis, as well as transforming growth factor-beta sequestration. A role for fibrillin microfibrils in tissue elasticity has been implied by their ability to increase periodicity from 56 to 150 nm. In this study, we found that microfibril periodicity and structure are dependent on the ionic strength of the buffer and Ca(2+) concentration; we then used these properties of the microfibril to trap conformation intermediates. Transmission electron microscopy imaging of microfibrils with a range of periodicities between 56 and 154 nm revealed a gross conformational change in the interbead region that accommodates the length change. At periodicities below 85 nm, four thin filaments are visualized in the interbead region, but at periodicities greater than 85 nm, two thick filaments are seen. The diameter of the bead remains almost constant at all periodicities, but there is a decrease in stain-exclusion above 85 nm periodicity, which is likely to correspond to a decrease in bead mass. Additionally, we identified eight molecules in cross-section through a microfibril, allowing us to understand microfibril organization in three dimensions. In conclusion, when microfibrils extend, there is a large molecular rearrangement within the interbead region, and this highlights a possible role for Ca(2+) in stabilizing the microfibril architecture and moderating extension in vivo.
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Affiliation(s)
- Ming-Chuan Wang
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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Abstract
PURPOSE OF REVIEW The mechanisms implicated in the clinical manifestations of zonular diseases, especially ectopia lentis, are reviewed. RECENT FINDINGS The molecular mechanisms involve fibrillin in a large spectrum of heritable diseases characterized by zonular stretching. The usual complications are refractive errors, especially myopia, glaucoma (either primary open angle, secondary angle closure and pupil block by anterior displacement of the lens) and retinal detachment. SUMMARY The genetics and molecular understanding provide information for genetic counseling. Treatment of myopia and glaucoma depend on the underlying mechanism, and lens surgery techniques are continuously improved.
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Nemet AY, Assia EI, Apple DJ, Barequet IS. Current concepts of ocular manifestations in Marfan syndrome. Surv Ophthalmol 2006; 51:561-75. [PMID: 17134646 DOI: 10.1016/j.survophthal.2006.08.008] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Marfan syndrome is a widespread disorder of connective tissue. It is characterized by systemic and ocular features due to mutations in the fibrillin gene. Awareness and prompt recognition of the ocular complications of Marfan syndrome may enable improvement and preservation of sight. Studies have been performed in the last few years that enable a better understanding of the genetics of the syndrome, earlier diagnosis, and improvement in the surgical techniques and options.
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Affiliation(s)
- Arie Y Nemet
- Department of Ophthalmology, Sapir Medical Center, Kfar Sava, Sackler Faculty of Medicine, Tel Aviv University, Israel
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Marfan Syndrome-causing Mutations in Fibrillin-1 Result in Gross Morphological Alterations and Highlight the Structural Importance of the Second Hybrid Domain. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84100-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Mellody KT, Freeman LJ, Baldock C, Jowitt TA, Siegler V, Raynal BDE, Cain SA, Wess TJ, Shuttleworth CA, Kielty CM. Marfan syndrome-causing mutations in fibrillin-1 result in gross morphological alterations and highlight the structural importance of the second hybrid domain. J Biol Chem 2006; 281:31854-62. [PMID: 16905551 DOI: 10.1074/jbc.m602743200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in fibrillin-1 result in Marfan syndrome, which affects the cardiovascular, skeletal and ocular systems. The multiorgan involvement and wide spectrum of associated phenotypes highlights the complex pathogenesis underlying Marfan syndrome. To elucidate the genotype to phenotype correlations, we engineered four Marfan syndrome causing mutations into a fibrillin-1 fragment encoded by exons 18-25, a region known to interact with tropoelastin. Biophysical and biochemical approaches, including small angle x-ray scattering, analytical ultracentrifugation, and circular dichroism, were used to study the impact of these mutations upon the structure and function of the protein. Mutations G880S, C862R, and C908R, situated within the second hybrid domain, disrupted the ratio of alpha-helix to beta-sheet leading to a more compact conformation. These data clearly demonstrate the importance of the previously uncharacterized hybrid domain in fibrillin-1 structure. In contrast, mutation K1023N situated within the linker region between the third eight cysteine motif and cbEGF 11 markedly extended the length of the fragment. However, none of the mutations affected tropoelastin binding. The profound effects of all four mutations on fragment conformation suggest that they contribute to the pathogenesis of Marfan syndrome by disrupting protein folding and its assembly into fibrillin-rich microfibrils.
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Affiliation(s)
- Kieran T Mellody
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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Lu Y, Sherratt MJ, Wang MC, Baldock C. Tissue specific differences in fibrillin microfibrils analysed using single particle image analysis. J Struct Biol 2006; 155:285-93. [PMID: 16697222 DOI: 10.1016/j.jsb.2006.03.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 03/20/2006] [Indexed: 11/19/2022]
Abstract
Fibrillin microfibrils endow mammalian connective tissues with elasticity and play a fundamental role in the deposition of elastin. The microfibrils are 57 nm periodic supramolecular protein polymers with a mass of 2.5 MDa per repeat. The organisation of molecules within a microfibril is still open to debate and structural studies are only just starting to unravel this issue. The contribution of microfibril associated proteins to microfibril ultrastructure and whether there are any tissue specific differences in microfibril structure is still unknown. Therefore, we have used low dose electron microscopy, single particle image analysis and atomic force microscopy to study the structure of fibrillin microfibrils from different tissues. EM images of microfibrils from aorta, ciliary zonules and vitreous humor were collected and more than 500 microfibril repeats from each sample were subjected to averaging. Averages from each sample were analysed using axial stain exclusion patterns and difference images to detect any variations between them. The overall morphology of fibrillin microfibrils was conserved between tissues and there were only very minor differences in the bead and shoulder region of microfibrils. These data suggest that the structure of isolated microfibrils represents the fibrillin scaffold, and either microfibril associated molecules are lost on purification or play only a minor role in microfibril structure.
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Affiliation(s)
- Yinhui Lu
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
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Morris RA, Dubielzig RR. Light-microscopy evaluation of zonular fiber morphology in dogs with glaucoma: secondary to lens displacement. Vet Ophthalmol 2005; 8:81-4. [PMID: 15762920 DOI: 10.1111/j.1463-5224.2005.00340.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lens displacement resulting in secondary glaucoma is common in terrier breeds. This study was carried out to evaluate whether light microscopy was useful in detecting abnormal patterns in zonular fiber protein. Eyes from 63 dogs with glaucoma secondary to lens displacement were evaluated for the presence of abnormal zonular fiber morphology using the following stains: hematoxylin and eosin, periodic acid Schiff (PAS), Masson's trichrome and Verhoeff's elastin stains. Two distinct forms of abnormal zonular fiber morphology were recognized and designated as zonular fiber dysplasia (ZFD) and zonular fiber collagenization (ZFC). ZFD protein morphology was characterized by being tightly adherent to the nonpigmented ciliary body epithelium, exhibiting a distinct lamellar and cross-hatched pattern and staining strongly positive with PAS and trichrome stains, and staining negative with elastin stains. ZFD was predominant in terrier breeds (18 of 29) and Shar-Pei dogs (4 of 29). ZFC abnormality was characterized by excessive zonular fiber that was not tightly adherent to the ciliary body epithelium and staining positive with PAS, trichrome (blue for collagen) and elastin stains. Only 7 of 19 dogs with ZFC changes were terrier breeds, and there was no pattern in the breeds affected. Fifteen of the 63 dogs used in the study had normal appearing zonular fibers. The staining pattern in these dogs matched normal controls by staining positive with PAS and Verhoeff's elastin stains and had only minimal positive staining with Masson's trichrome stain. Results suggest that light microscopy is useful in detecting breed-related changes in zonular fiber morphology in cases of glaucoma secondary to lens displacement. These changes may correlate with the presence of abnormal zonular fiber proteins and might be important in the pathogenesis of primary lens displacement in terrier and Shar-Pei dogs.
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Affiliation(s)
- Rebecca A Morris
- School of Veterinary Medicine, Comparative Ocular Pathology Laboratory of Wisconsin University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, USA
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Lu Y, Holmes DF, Baldock C. Evidence for the Intramolecular Pleating Model of Fibrillin Microfibril Organisation from Single Particle Image Analysis. J Mol Biol 2005; 349:73-85. [PMID: 15876369 DOI: 10.1016/j.jmb.2005.03.066] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 03/18/2005] [Accepted: 03/23/2005] [Indexed: 11/25/2022]
Abstract
Fibrillin microfibrils endow mammalian connective tissues with elasticity and are fundamental for the deposition of elastin. The microfibrils are 57nm periodic supramolecular protein polymers with a mass of 2.4MDa per repeat. The detailed structure and organisation of most matrix assemblies is poorly understood due to their large size and complexity and it has proved a major challenge to define their structural organisation. Therefore, we have used low dose electron microscopy and single particle image analysis to study the structure of fibrillin microfibrils. Three novel features were detected: a globular feature that bridges the "arm" region, a double band of density crossing the microfibril and stain penetrating holes present in the interbead region, possibly produced by the removal of microfibril associated proteins in the purification procedure. Fine filaments of approximately 2.4nm diameter are resolved in the interbead region, which correspond to the reported diameter of the fibrillin molecule. Comparison of the stain exclusion pattern of microfibrils with the theoretical stain exclusion pattern of fibrillin packing models indicates that the intramolecular pleating model, where each fibrillin molecule is pleated within one microfibril period allowing extensibility by unpleating, has the best fit to the data.
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Affiliation(s)
- Yinhui Lu
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, Michael Smith Building, University of Manchester, Manchester, M13 9PT, UK
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Marson A, Rock MJ, Cain SA, Freeman LJ, Morgan A, Mellody K, Shuttleworth CA, Baldock C, Kielty CM. Homotypic Fibrillin-1 Interactions in Microfibril Assembly. J Biol Chem 2005; 280:5013-21. [PMID: 15569675 DOI: 10.1074/jbc.m409029200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have defined the homotypic interactions of fibrillin-1 to obtain new insights into microfibril assembly. Dose-dependent saturable high affinity binding was demonstrated between N-terminal fragments, between furin processed C-terminal fragments, and between these N- and C-terminal fragments. The N terminus also interacted with a downstream fragment. A post-furin cleavage site C-terminal sequence also interacted with the N terminus, with itself and with the furin-processed fragment. No other homotypic fibrillin-1 interactions were detected. Some terminal homotypic interactions were inhibited by other terminal sequences, and were strongly calcium-dependent. Treatment of an N-terminal fragment with N-ethylmaleimide reduced homotypic binding. Microfibril-associated glycoprotein-1 inhibited N- to C-terminal interactions but not homotypic N-terminal interactions. These fibrillin-1 interactions are likely to regulate pericellular fibrillin-1 microfibril assembly.
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Affiliation(s)
- Andrew Marson
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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Abstract
Fibrillin microfibrils are widely distributed extracellular matrix assemblies that endow elastic and nonelastic connective tissues with long-range elasticity. They direct tropoelastin deposition during elastic fibrillogenesis and form an outer mantle for mature elastic fibers. Microfibril arrays are also abundant in dynamic tissues that do not express elastin, such as the ciliary zonules of the eye. Mutations in fibrillin-1-the principal structural component of microfibrils-cause Marfan syndrome, a heritable disease with severe aortic, ocular, and skeletal defects. Isolated fibrillin-rich microfibrils have a complex 56 nm "beads-on-a-string" appearance; the molecular basis of their assembly and elastic properties, and their role in higher-order elastic fiber formation, remain incompletely understood.
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Affiliation(s)
- Cay M Kielty
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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Kielty CM, Wess TJ, Haston L, Ashworth JL, Sherratt MJ, Shuttleworth CA. Fibrillin-rich microfibrils: elastic biopolymers of the extracellular matrix. J Muscle Res Cell Motil 2003; 23:581-96. [PMID: 12785107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Fibrillin-rich microfibrils are evolutionarily ancient macromolecular assemblies of the extracellular matrix. They have unique extensible properties that endow vascular and other tissues with long-range elasticity. Microfibril extensibility supports the low pressure closed circulations of lower organisms such as crustaceans. In higher vertebrates, microfibrils act as a template for elastin deposition and are components of mature elastic fibres. In man, the importance of microfibrils is highlighted by the linkage of mutations in their principal structural component, fibrillin-1, to the heritable disease Marfan syndrome which is characterised by severe cardiovascular, skeletal and ocular defects. When isolated from tissues, fibrillin-rich microfibrils have a complex ultrastructural organisation with a characteristic 'beads-on-a-strong' appearance. X-ray fibre diffraction studies and biomechanical testing have shown that microfibrils are reversibly extensible at tissue extensions of 100%. Ultrastructural analysis and 3D reconstructions of isolated microfibrils using automated electron tomography have revealed new details of how fibrillin molecules are aligned within microfibrils in untensioned and extended states, and delineated the role of calcium in regulating microfibril beaded periodicity, rest length and molecular organisation. The molecular basis of how fibrillin molecules assemble into microfibrils, the central role of cells in regulating this process, and the identity of other molecules that may coassemble into microfibrils are now being elucidated. This information will enhance our understanding of the elastic mechanism of these unique extracellular matrix polymers, and may lead to new microfibril-based strategies for repairing elastic tissues in ageing and disease.
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Affiliation(s)
- C M Kielty
- School of Medicine, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK.
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Abstract
Elastic fibres are essential extracellular matrix macromolecules comprising an elastin core surrounded by a mantle of fibrillin-rich microfibrils. They endow connective tissues such as blood vessels, lungs and skin with the critical properties of elasticity and resilience. The biology of elastic fibres is complex because they have multiple components, a tightly regulated developmental deposition, a multi-step hierarchical assembly and unique biomechanical functions. However, their molecular complexity is at last being unravelled by progress in identifying interactions between component molecules, ultrastructural analyses and studies of informative mouse models.
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Affiliation(s)
- Cay M Kielty
- School of Medicine, University of Manchester, UK.
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Kielty CM, Baldock C, Lee D, Rock MJ, Ashworth JL, Shuttleworth CA. Fibrillin: from microfibril assembly to biomechanical function. Philos Trans R Soc Lond B Biol Sci 2002; 357:207-17. [PMID: 11911778 PMCID: PMC1692929 DOI: 10.1098/rstb.2001.1029] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Fibrillins form the structural framework of a unique and essential class of extracellular microfibrils that endow dynamic connective tissues with long-range elasticity. Their biological importance is emphasized by the linkage of fibrillin mutations to Marfan syndrome and related connective tissue disorders, which are associated with severe cardiovascular, ocular and skeletal defects. These microfibrils have a complex ultrastructure and it has proved a major challenge both to define their structural organization and to relate it to their biological function. However, new approaches have at last begun to reveal important insights into their molecular assembly, structural organization and biomechanical properties. This paper describes the current understanding of the molecular assembly of fibrillin molecules, the alignment of fibrillin molecules within microfibrils and the unique elastomeric properties of microfibrils.
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Affiliation(s)
- Cay M Kielty
- School of Medicine, University of Manchester, Manchester M13 9PT, UK.
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Saika S, Miyamoto T, Tanaka T, Ishida I, Ohnishi Y, Ooshima A. Latent TGFbeta binding protein-1 and fibrillin-1 in human capsular opacification and in cultured lens epithelial cells. Br J Ophthalmol 2001; 85:1362-6. [PMID: 11673307 PMCID: PMC1723781 DOI: 10.1136/bjo.85.11.1362] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND/AIM It was previously reported that collagenous extracellular matrix (ECM) in human capsular opacification contained isoforms of transforming growth factor beta (TGFbeta). In the present study, the authors performed immunohistochemistry to examine whether ECM in human capsular opacification and in cultures of bovine lens epithelial cells (LECs) contained latent TGFbeta binding protein-1 (LTBP-1), TGFbeta1 latency associated peptide (beta1-LAP), and fibrillin-1, a suspected ligand of LTBP-1 as well as a component of the extracellular microfibrillar apparatus. The aim of the study was to further clarify the mechanism of TGFbeta1 deposition in ECM of capsular opacification. METHODS Human capsular opacification specimens and uninjured lens capsules, as well as cultured bovine LECs, were processed for immunohistochemistry using antibodies against LTBP-1, beta1-LAP, fibrillin-1, and collagen type I. RESULTS LTBP-1, beta1-LAP, and fibrillin-1 all were localised to the ECM in human capsular opacification. Uninjured lens epithelium stained for beta1-LAP, but not for LTBP-1 and fibrillin-1. ECM deposited in confluent LEC cultures stained for LTBP-1, beta1-LAP, and fibrillin-1, while cultures with only sparse cellularity were unstained for LTBP-1 or fibrillin-1. CONCLUSIONS LECs upregulate LTBP-1 and fibrillin-1 during postoperative healing. LTBP-1, beta1-LAP, and fibrillin-1 colocalised to the ECM in capsular opacification and in confluent LEC cultures. TGFbeta1 is considered to deposit in ECM in the large latent form. ECM secreted by LEC may function as a scavenger or repository of TGFbeta.
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Affiliation(s)
- S Saika
- Department of Ophthalmology, Wakayama Medical University School of Medicine, 811-1 Kimidera, Wakayama, 641-8509, Japan.
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