1
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Boushehri S, Holey H, Brosz M, Gumbsch P, Pastewka L, Aponte-Santamaría C, Gräter F. O-glycans Expand Lubricin and Attenuate Its Viscosity and Shear Thinning. Biomacromolecules 2024; 25:3893-3908. [PMID: 38815979 PMCID: PMC11238335 DOI: 10.1021/acs.biomac.3c01348] [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: 12/07/2023] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 06/01/2024]
Abstract
Lubricin, an intrinsically disordered glycoprotein, plays a pivotal role in facilitating smooth movement and ensuring the enduring functionality of synovial joints. The central domain of this protein serves as a source of this excellent lubrication and is characterized by its highly glycosylated, negatively charged, and disordered structure. However, the influence of O-glycans on the viscosity of lubricin remains unclear. In this study, we employ molecular dynamics simulations in the absence and presence of shear, along with continuum simulations, to elucidate the intricate interplay between O-glycans and lubricin and the impact of O-glycans on lubricin's conformational properties and viscosity. We found the presence of O-glycans to induce a more extended conformation in fragments of the disordered region of lubricin. These O-glycans contribute to a reduction in solution viscosity but at the same time weaken shear thinning at high shear rates, compared to nonglycosylated systems with the same density. This effect is attributed to the steric and electrostatic repulsion between the fragments, which prevents their conglomeration and structuring. Our computational study yields a mechanistic mechanism underlying previous experimental observations of lubricin and paves the way to a more rational understanding of its function in the synovial fluid.
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Affiliation(s)
- Saber Boushehri
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, Heidelberg 69118, Germany
- University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg 69120, Germany
- Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Hannes Holey
- Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Department of Microsystems Engineering, University of Freiburg, Georges-Köhler-Allee 103, Freiburg 79110, Germany
| | - Matthias Brosz
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, Heidelberg 69118, Germany
- University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg 69120, Germany
| | - Peter Gumbsch
- Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Fraunhofer IWM, Wöhlerstraße 11, Freiburg 79108, Germany
| | - Lars Pastewka
- Department of Microsystems Engineering, University of Freiburg, Georges-Köhler-Allee 103, Freiburg 79110, Germany
| | - Camilo Aponte-Santamaría
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, Heidelberg 69118, Germany
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, Heidelberg 69118, Germany
- University of Heidelberg, Im Neuenheimer Feld 205, Heidelberg 69120, Germany
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2
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Ghelich P, Samandari M, Hassani Najafabadi A, Tanguay A, Quint J, Menon N, Ghanbariamin D, Saeedinejad F, Alipanah F, Chidambaram R, Krawetz R, Nuutila K, Toro S, Barnum L, Jay GD, Schmidt TA, Tamayol A. Dissolvable Immunomodulatory Microneedles for Treatment of Skin Wounds. Adv Healthc Mater 2024; 13:e2302836. [PMID: 38299437 DOI: 10.1002/adhm.202302836] [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: 08/31/2023] [Revised: 12/21/2023] [Indexed: 02/02/2024]
Abstract
Sustained inflammation can halt or delay wound healing, and macrophages play a central role in wound healing. Inflammatory macrophages are responsible for the removal of pathogens, debris, and neutrophils, while anti-inflammatory macrophages stimulate various regenerative processes. Recombinant human Proteoglycan 4 (rhPRG4) is shown to modulate macrophage polarization and to prevent fibrosis and scarring in ear wound healing. Here, dissolvable microneedle arrays (MNAs) carrying rhPRG4 are engineered for the treatment of skin wounds. The in vitro experiments suggest that rhPRG4 modulates the inflammatory function of bone marrow-derived macrophages. Degradable and detachable microneedles are developed from gelatin methacryloyl (GelMA) attach to a dissolvable gelatin backing. The developed MNAs are able to deliver a high dose of rhPRG4 through the dissolution of the gelatin backing post-injury, while the GelMA microneedles sustain rhPRG4 bioavailability over the course of treatment. In vivo results in a murine model of full-thickness wounds with impaired healing confirm a decrease in inflammatory biomarkers such as TNF-α and IL-6, and an increase in angiogenesis and collagen deposition. Collectively, these results demonstrate rhPRG4-incorporating MNA is a promising platform in skin wound healing applications.
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Affiliation(s)
- Pejman Ghelich
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Mohamadmahdi Samandari
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Alireza Hassani Najafabadi
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Adam Tanguay
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Jacob Quint
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Nikhil Menon
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Delaram Ghanbariamin
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Farnoosh Saeedinejad
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Fatemeh Alipanah
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Ramaswamy Chidambaram
- Center for Comparative Medicine, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Roman Krawetz
- McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, AB, T2N 4Z6, Canada
- Department of Surgery, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Kristo Nuutila
- US Army Institute of Surgical Research, Fort Sam Houston, Texas, 78234, USA
| | - Steven Toro
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Lindsay Barnum
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Gregory D Jay
- Emergency Medicine, Brown University, Providence, RI, 02908, USA
| | - Tannin A Schmidt
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Ali Tamayol
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, CT, 06030, USA
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3
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Martin-Alarcon L, Govedarica A, Ewoldt RH, Bryant SL, Jay GD, Schmidt TA, Trifkovic M. Scale-Dependent Rheology of Synovial Fluid Lubricating Macromolecules. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306207. [PMID: 38161247 DOI: 10.1002/smll.202306207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 11/20/2023] [Indexed: 01/03/2024]
Abstract
Synovial fluid (SF) is the complex biofluid that facilitates the exceptional lubrication of articular cartilage in joints. Its primary lubricating macromolecules, the linear polysaccharide hyaluronic acid (HA) and the mucin-like glycoprotein proteoglycan 4 (PRG4 or lubricin), interact synergistically to reduce boundary friction. However, the precise manner in which these molecules influence the rheological properties of SF remains unclear. This study aimed to elucidate this by employing confocal microscopy and multiscale rheometry to examine the microstructure and rheology of solutions containing recombinant human PRG4 (rhPRG4) and HA. Contrary to previous assumptions of an extensive HA-rhPRG4 network, it is discovered that rhPRG4 primarily forms stiff, gel-like aggregates. The properties of these aggregates, including their size and stiffness, are found to be influenced by the viscoelastic characteristics of the surrounding HA matrix. Consequently, the rheology of this system is not governed by a single length scale, but instead responds as a disordered, hierarchical network with solid-like rhPRG4 aggregates distributed throughout the continuous HA phase. These findings provide new insights into the biomechanical function of PRG4 in cartilage lubrication and may have implications in the development of HA-based therapies for joint diseases like osteoarthritis.
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Affiliation(s)
- Leonardo Martin-Alarcon
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Aleksandra Govedarica
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Randy H Ewoldt
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Steven L Bryant
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Gregory D Jay
- Department of Emergency Medicine - Warren Alpert Medical School & School of Engineering, Brown University, Providence, RI, 02912, USA
| | - Tannin A Schmidt
- Biomedical Engineering Department, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Milana Trifkovic
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada
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4
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Ninkovic N, Sparks HD, Ponjevic D, Muench G, Biernaskie JA, Krawetz RJ. Proteoglycan 4 (PRG4) treatment improves skin wound healing in a porcine model. FASEB J 2024; 38:e23547. [PMID: 38498368 DOI: 10.1096/fj.202301289rrr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 02/08/2024] [Accepted: 02/26/2024] [Indexed: 03/20/2024]
Abstract
Proteoglycan 4 (PRG4) is a boundary lubricant originally identified in articular cartilage and has been since shown to have immunomodulation and antifibrotic properties. Previously, we have demonstrated that recombinant human (rh)PRG4 treatment accelerates auricular cartilage injury closure through an inhibition of the fibrotic response, and promotion of tissue regeneration in mice. The purpose of the current study was to examine the effects of rhPRG4 treatment (vs. a DMSO carried control) on full-thickness skin wound healing in a preclinical porcine model. Our findings suggest that while rhPRG4 did not significantly accelerate nor impede full-thickness skin wound closure, it did improve repair quality by decreasing molecular markers of fibrosis and increasing re-vascularization. We also demonstrated that rhPRG4 treatment increased dermal adipose tissue during the healing process specifically by retaining adipocytes in the wound area but did not inhibit lipolysis. Overall, the results of the current study have demonstrated that rhPRG4 acts as antifibrotic agent and regulates dermal adipose tissue during the healing processes resulting in a tissue with a trajectory that more resembles the native skin vs. a fibrotic patch. This study provides strong rationale to examine if rhPRG4 can improve regeneration in human wounds.
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Affiliation(s)
- Nicoletta Ninkovic
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, Alberta, Canada
| | - Holly D Sparks
- McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, Alberta, Canada
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Dragana Ponjevic
- McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, Alberta, Canada
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Greg Muench
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jeff A Biernaskie
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Roman J Krawetz
- McCaig Institute for Bone & Joint Health, University of Calgary, Calgary, Alberta, Canada
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Biomedical Engineering, University of Calgary, Calgary, Alberta, Canada
- Department Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
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5
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Madl AC, Liu C, Cirera-Salinas D, Fuller GG, Myung D. A Mucin-Deficient Ocular Surface Mimetic Platform for Interrogating Drug Effects on Biolubrication, Antiadhesion Properties, and Barrier Functionality. ACS APPLIED MATERIALS & INTERFACES 2022; 14:18016-18030. [PMID: 35416028 PMCID: PMC9052192 DOI: 10.1021/acsami.1c22280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 03/03/2022] [Indexed: 05/14/2023]
Abstract
Dry eye disease (DED) affects more than 100 million people worldwide, causing significant patient discomfort and imposing a multi-billion-dollar burden on global health care systems. In DED patients, the natural biolubrication process that facilitates pain-free blinking goes awry due to an imbalance of lipids, aqueous medium, and mucins in the tear film, resulting in ocular surface damage. Identifying strategies to reduce adhesion and shear stresses between the ocular surface and the conjunctival cells lining the inside of the eyelid during blink cycles is a promising approach to improve the signs and symptoms of DED. However, current preclinical models for screening ocular lubricants rely on scarce, heterogeneous tissue samples or model substrates that do not capture the complex biochemical and biophysical cues present at the ocular surface. To recapitulate the hierarchical architecture and phenotype of the ocular interface for preclinical drug screening, we developed an in vitro mucin-deficient DED model platform that mimics the complexity of the ocular interface and investigated its utility in biolubrication, antiadhesion, and barrier protection studies using recombinant human lubricin, a promising investigational therapy for DED. The biomimetic platform recapitulated the pathological changes in biolubrication, adhesion, and barrier functionality often observed in mucin-deficient DED patients and demonstrated that recombinant human lubricin can reverse the damage induced by mucin loss in a dose- and conformation-dependent manner. Taken together, these results highlight the potential of the platform─and recombinant human lubricin─in advancing the standard of care for mucin-deficient DED patients.
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Affiliation(s)
- Amy C. Madl
- Department
of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Chunzi Liu
- Department
of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Daniel Cirera-Salinas
- Biologics
Analytical Research and Development, Novartis
Pharma AG, Basel 4002, Switzerland
| | - Gerald G. Fuller
- Department
of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - David Myung
- Department
of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Byers
Eye Institute, Stanford University School
of Medicine, Palo Alto, California 94303, United States
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6
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Das N, Menon NG, de Almeida LGN, Woods PS, Heynen ML, Jay GD, Caffery B, Jones L, Krawetz R, Schmidt TA, Dufour A. Proteomics Analysis of Tears and Saliva From Sjogren's Syndrome Patients. Front Pharmacol 2021; 12:787193. [PMID: 34950038 PMCID: PMC8689002 DOI: 10.3389/fphar.2021.787193] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/02/2021] [Indexed: 12/17/2022] Open
Abstract
Sjogren's syndrome (SS) is characterized by dysfunctional mucous membranes and dysregulated moisture-secreting glands resulting in various symptoms, including dry mouth and dry eyes. Here, we wanted to profile and compare the tear and saliva proteomes of SS patients to healthy controls. Tear and saliva samples were collected and subjected to an isotopic dimethylation labeling shotgun proteomics workflow to identify alterations in protein levels. In tear samples, we identified 83 upregulated and 112 downregulated proteins. Pathway enrichment analysis of the changing proteins by Metascape identified leukocyte transendothelial migration, neutrophil degranulation, and post-translation protein phosphorylation in tears of SS patients. In healthy controls' tears, an enrichment for proteins related to glycolysis, amino acid metabolism and apoptotic signaling pathway were identified. In saliva, we identified 108 upregulated and 45 downregulated proteins. Altered pathways in SS patients' saliva included cornification, sensory perception to taste and neutrophil degranulation. In healthy controls' saliva, an enrichment for proteins related to JAK-STAT signaling after interleukin-12 stimulation, phagocytosis and glycolysis in senescence were identified. Dysregulated protease activity is implicated in the initiation of inflammation and immune cell recruitment in SS. We identified 20 proteases and protease inhibitors in tears and 18 in saliva which are differentially expressed between SS patients and healthy controls. Next, we quantified endogenous proteoglycan 4 (PRG4), a mucin-like glycoprotein, in tear wash and saliva samples via a bead-based immune assay. We identified decreased levels of PRG4 in SS patients' tear wash compared to normal samples. Conversely, in saliva, we found elevated levels of PRG4 concentration and visualized PRG4 expression in human parotid gland via immunohistological staining. These findings will improve our mechanistic understanding of the disease and changes in SS patients' protein expression will help identify new potential drug targets. PRG4 is among the promising targets, which we identified here, in saliva, for the first time.
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Affiliation(s)
- Nabangshu Das
- Departments of Physiology and Pharmacology and Kinesiology, University of Calgary, Calgary, AB, Canada
- McCaig Institute, University of Calgary, Calgary, AB, Canada
| | - Nikhil G. Menon
- Department of Biomedical Engineering, School of Dental Medicine, UConn Health, Farmington, CT, United States
| | - Luiz G. N. de Almeida
- Departments of Physiology and Pharmacology and Kinesiology, University of Calgary, Calgary, AB, Canada
- McCaig Institute, University of Calgary, Calgary, AB, Canada
| | - Paige S. Woods
- Department of Emergency Medicine, Warren Alpert Medical School and School of Engineering, Brown University, Providence, RI, United States
| | - Miriam L. Heynen
- Centre for Ocular Research and Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Gregory D. Jay
- Department of Emergency Medicine, Warren Alpert Medical School and School of Engineering, Brown University, Providence, RI, United States
| | | | - Lyndon Jones
- Centre for Ocular Research and Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Roman Krawetz
- McCaig Institute, University of Calgary, Calgary, AB, Canada
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Tannin A. Schmidt
- McCaig Institute, University of Calgary, Calgary, AB, Canada
- Department of Biomedical Engineering, School of Dental Medicine, UConn Health, Farmington, CT, United States
| | - Antoine Dufour
- Departments of Physiology and Pharmacology and Kinesiology, University of Calgary, Calgary, AB, Canada
- McCaig Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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7
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Matheson AR, Sheehy EJ, Jay GD, Scott WM, O'Brien FJ, Schmidt TA. The role of synovial fluid constituents in the lubrication of collagen-glycosaminoglycan scaffolds for cartilage repair. J Mech Behav Biomed Mater 2021; 118:104445. [PMID: 33740688 DOI: 10.1016/j.jmbbm.2021.104445] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 02/15/2021] [Accepted: 03/02/2021] [Indexed: 11/18/2022]
Abstract
Extracellular matrix (ECM)-derived scaffolds have shown promise as tissue-engineered grafts for promoting cartilage repair. However, there has been a lack of focus on fine-tuning the frictional properties of scaffolds for cartilage tissue engineering as well as understanding their interactions with synovial fluid constituents. Proteoglycan-4 (PRG4) and hyaluronan (HA) are macromolecules within synovial fluid that play key roles as boundary mode lubricants during cartilage surface interactions. The overall objective of this study was to characterize the role PRG4 and HA play in the lubricating function of collagen-glycosaminoglycan (GAG) scaffolds for cartilage repair. As a first step towards this goal, we aimed to develop a suitable in vitro friction test to establish the boundary mode lubrication parameters for collagen-GAG scaffolds articulated against glass in a phosphate buffered saline (PBS) bath. Subsequently, we sought to leverage this system to determine the effect of physiological synovial fluid lubricants, PRG4 and HA, on the frictional properties of collagen-GAG scaffolds, with scaffolds hydrated in PBS and bovine synovial fluid (bSF) serving as negative and positive controls, respectively. At all compressive strains examined (ε = 0.1-0.5), fluid depressurization within hydrated collagen-GAG scaffolds was >99% complete at ½ minute. The coefficient of friction was stable at all compressive strains (ranging from a low 0.103 ± 0.010 at ε = 0.3 up to 0.121 ± 0.015 at ε = 0.4) and indicative of boundary-mode conditions. Immunohistochemistry demonstrated that PRG4 from recombinant human (rh) and bovine sources adsorbed to collagen-GAG scaffolds and the coefficient of friction for scaffolds immersed in rhPRG4 (0.067 ± 0.027) and normal bSF (0.056 ± 0.020) solution decreased compared to PBS (0.118 ± 0.21, both p < 0.05, at ε = 0.2). The ability of the adsorbed rhPRG4 to reduce friction on the scaffolds indicates that its incorporation within collagen-GAG biomaterials may enhance their lubricating ability as potential tissue-engineered cartilage replacements. To conclude, this study reports the development of an in vitro friction test capable of characterizing the coefficient of friction of ECM-derived scaffolds tested in a range of synovial fluid lubricants and demonstrates frictional properties as a potential design parameter for implants and materials for soft tissue replacement.
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Affiliation(s)
- Austyn R Matheson
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada
| | - Eamon J Sheehy
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland; Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, Ireland
| | - Gregory D Jay
- Department of Emergency Medicine, Warren Alpert Medical School & School of Engineering, Brown University, Providence, RI, USA
| | - W Michael Scott
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Fergal J O'Brien
- Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland; Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, Ireland
| | - Tannin A Schmidt
- Biomedical Engineering Department, University of Connecticut Health Center, Farmington, CT, USA.
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9
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Hino T, Furumatsu T, Miyazawa S, Fujii M, Kodama Y, Kamatsuki Y, Okazaki Y, Masuda S, Okazaki Y, Ozaki T. A histological study of the medial meniscus posterior root tibial insertion. Connect Tissue Res 2020; 61:546-553. [PMID: 31181971 DOI: 10.1080/03008207.2019.1631298] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Purpose/Aim of the study: Posterior root injury of the medial meniscus often leads to articular cartilage degeneration due to altered biomechanics. To avoid dysfunction, the attachment must be repaired using the transtibial pullout technique. To guide appropriate placement of the tibial tunnel, additional details on the normal anatomy of the meniscus insertion are needed. Therefore, we performed a histological analysis of a tibial bone slice with the medial meniscus posterior insertion obtained during total knee arthroplasty surgery. Materials and methods: Horizontal slices of the proximal tibia were obtained from 7 patients with osteoarthritis who underwent total knee arthroplasty. After decalcification, the region of the posterior horn was cut out and segmented into four pieces (2.0 mm thickness; medial to lateral). Sagittal sections were evaluated by safranin O staining or immunohistochemistry with anti-type collagen antibody. Results: Safranin O staining showed that the insertion of the posterior root consisted primarily of fibrocartilaginous layers in segment 2. Anatomically, segment 2 corresponded to the sagittal plane passing through the peak of the medial intercondylar tubercle. In this section, safranin O staining and immunohistochemistry revealed that the anterior one-third of the posterior root insertion was richer in proteoglycans and type II collagen than the central and posterior one-third. Conclusions: Anatomical insertion of the posterior root of the medial meniscus was located at the sagittal plane passing through the peak of the medial intercondylar tubercle. The structure of the medial meniscus posterior insertion was mainly localized in the anterior one-third.
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Affiliation(s)
- Tomohito Hino
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Takayuki Furumatsu
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Shinichi Miyazawa
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Masataka Fujii
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Yuya Kodama
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Yusuke Kamatsuki
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Yoshiki Okazaki
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Shin Masuda
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Yuki Okazaki
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
| | - Toshifumi Ozaki
- Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
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10
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Sarkar A, Chanda A, Regmi SC, Karve K, Deng L, Jay GD, Jirik FR, Schmidt TA, Bonni S. Recombinant human PRG4 (rhPRG4) suppresses breast cancer cell invasion by inhibiting TGFβ-Hyaluronan-CD44 signalling pathway. PLoS One 2019; 14:e0219697. [PMID: 31361756 PMCID: PMC6667139 DOI: 10.1371/journal.pone.0219697] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 06/28/2019] [Indexed: 01/02/2023] Open
Abstract
Metastasis is the major cause of cancer-related morbidity and mortality. The ability of cancer cells to become invasive and migratory contribute significantly to metastatic growth, which necessitates the identification of novel anti-migratory and anti-invasive therapeutic approaches. Proteoglycan 4 (PRG4), a mucin-like glycoprotein, contributes to joint synovial homeostasis through its friction-reducing and anti-adhesive properties. Adhesion to surrounding extracellular matrix (ECM) components is critical for cancer cells to invade the ECM and eventually become metastatic, raising the question whether PRG4 has an anti-invasive effect on cancer cells. Here, we report that a full-length recombinant human PRG4 (rhPRG4) suppresses the ability of the secreted protein transforming growth factor beta (TGFβ) to induce phenotypic disruption of three-dimensional human breast cancer cell-derived organoids by reducing ligand-induced cell invasion. In mechanistic studies, we find that rhPRG4 suppresses TGFβ-induced invasiveness of cancer cells by inhibiting the downstream hyaluronan (HA)-cell surface cluster of differentiation 44 (CD44) signalling axis. Furthermore, we find that rhPRG4 represses TGFβ-dependent increase in the protein abundance of CD44 and of the enzyme HAS2, which is involved in HA biosynthesis. It is widely accepted that TGFβ has both tumor suppressing and tumor promoting roles in cancer. The novel finding that rhPRG4 opposes HAS2 and CD44 induction by TGFβ has implications for downregulating the tumor promoting roles, while maintaining the tumor suppressive aspects of TGFβ actions. Finally, these findings point to rhPRG4's potential clinical utility as a therapeutic treatment for invasive and metastatic breast cancer.
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Affiliation(s)
- Anusi Sarkar
- The Arnie Charbonneau Cancer Institute and Department of Biochemistry & Molecular Biology, The Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Ayan Chanda
- The Arnie Charbonneau Cancer Institute and Department of Biochemistry & Molecular Biology, The Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Suresh C. Regmi
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Kunal Karve
- The Arnie Charbonneau Cancer Institute and Department of Biochemistry & Molecular Biology, The Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Lili Deng
- The Arnie Charbonneau Cancer Institute and Department of Biochemistry & Molecular Biology, The Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Gregory D. Jay
- Department of Emergency Medicine—Alpert Medical School & School of Engineering, Brown University, Providence, Rhode Island, United States of America
| | - Frank R. Jirik
- The Arnie Charbonneau Cancer Institute and Department of Biochemistry & Molecular Biology, The Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Tannin A. Schmidt
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Biomedical Engineering Department, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- * E-mail: (SB); (TS)
| | - Shirin Bonni
- The Arnie Charbonneau Cancer Institute and Department of Biochemistry & Molecular Biology, The Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- * E-mail: (SB); (TS)
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11
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Bloom AK, Samsom ML, Regmi SC, Steele BL, Schmidt TA. Investigating the effect of proteoglycan 4 on hyaluronan solution properties using confocal fluorescence recovery after photobleaching. BMC Musculoskelet Disord 2019; 20:93. [PMID: 30808331 PMCID: PMC6391837 DOI: 10.1186/s12891-019-2469-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/18/2019] [Indexed: 11/17/2022] Open
Abstract
Background The objective of this study was to use confocal fluorescence recovery after photobleaching (FRAP) to examine the specific and dose-dependent effect of proteoglycan 4 (PRG4) on hyaluronan (HA) solutions of different molecular weight; and assess the effect of reduction and alkylation (R/A) of PRG4 on its effects on HA solutions. Methods Confocal FRAP was used to determine the diffusion coefficient of fluorescein isothiocyanate (FITC)-dextran tracer (Dt) through 1500 kDa and 500 kDa HA solutions (0–3.3 mg/ml) ± PRG4 or a control protein, bovine serum albumin (BSA), at physiological (450 μg/ml) or pathophysiological (45 μg/ml) concentrations. The effect of PRG4 or R/A PRG4 on 1500 kDa HA solutions was also investigated. Empirical constants obtained from fitting data to the universal scaling equation were used to calculate the average distribution of apparent mesh sizes. Results PRG4 at both 45 and 450 μg/ml slowed the diffusion of the FITC-dextran tracer for all concentrations of HA and caused a decrease in the apparent mesh size within the HA solution. This effect was specific to PRG4, not observed with BSA, but not dependent on its tertiary/quaternary structure as the effect remained after R/A of PRG4. Conclusions These results demonstrate that PRG4 can significantly alter the solution properties of HA; PRG4 essentially reduced the permeability of the HA network. This effect may be due to PRG4 entangling HA molecules through binding and/or HA crowding PRG4 molecules into a self-assembled network. Collectively these findings contribute to the understanding of PRG4 and HA interaction(s) in solution and therefore the function of SF in diarthroidal joints.
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Affiliation(s)
- Adam K Bloom
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada
| | - Michael L Samsom
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada
| | - Suresh C Regmi
- Faculty of Kinesiology, KNB 426, 2500 University Dr. NW, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Bridgett L Steele
- Faculty of Kinesiology, KNB 426, 2500 University Dr. NW, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Tannin A Schmidt
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada. .,Faculty of Kinesiology, KNB 426, 2500 University Dr. NW, University of Calgary, Calgary, AB, T2N 1N4, Canada. .,Biomedical Engineering Department, University of Connecticut Health Center, Farmington, CT, USA.
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12
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Huang J, Qiu X, Xie L, Jay GD, Schmidt TA, Zeng H. Probing the Molecular Interactions and Lubrication Mechanisms of Purified Full-Length Recombinant Human Proteoglycan 4 (rhPRG4) and Hyaluronic Acid (HA). Biomacromolecules 2019; 20:1056-1067. [PMID: 30608145 DOI: 10.1021/acs.biomac.8b01678] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Probing the adsorption and lubrication behavior of lubricin, also known as proteoglycan 4 (PRG4), is important for understanding the ultralow friction of cartilage lubrication. Most previous research has focused on native lubricin either purified from synovial fluid or articular cartilage explant culture media. In this work, the adsorption behavior and lubrication mechanism of full-length recombinant human PRG4 (rhPRG4) on mica as well as the effect of adding hyaluronic acid (HA, a polysaccharide) were systematically investigated using a surface forces apparatus (SFA) technique. A low friction coefficient (μ ∼ 0.04) was measured when multilayer rhPRG4 (∼31 nm) was confined in between mica surfaces, even when the load increased to ∼1.2 MPa. Intriguingly, a previously unreported ultralow friction coefficient (μ < 0.005) was observed at a low sliding velocity ( v = 0.14 μm/s) with the applied load P reaching ∼3.6 MPa when a diluted rhPRG4 solution (∼90 μg/mL) was used. The distinct friction behavior is likely due to the smooth and more close-packed lubricin coating, as made evident by the atomic force microscope imaging. Adding HA onto multilayer rhPRG4-coated mica increased the friction coefficient μ to ∼0.1; however, the load bearing property increased, indicating potential synergistic effect between rhPRG4 and HA, which was further demonstrated by the weak adhesion observed when separating rhPRG4-coated mica and HA-coated aminopropyltriethoxysilane-mica (APTES-mica). Alternatively, adding premixed rhPRG4-HA on mica had a friction coefficient (μ ∼ 0.1) close to that of injecting concentrated rhPRG4 (∼450 μg/mL) with lower load sustainability. Our results provide fundamental insights into the adsorption and lubrication behavior of lubricin and its interaction with HA, with useful implications for the underlying mechanism of ultralow friction provided by synovial fluid.
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Affiliation(s)
- Jun Huang
- Center for Advanced Jet Engineering Technologies (CaJET), Key Laboratory of High-efficiency and Clean Mechanical Manufacture (Ministry of Education), Department of Mechanical Engineering , Shandong University , Jingshi Road 17923 , Jinan 250061 , China.,Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Xiaoyong Qiu
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Lei Xie
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Gregory D Jay
- Department of Emergency Medicine , Warren Alpert Medical School of Brown University , Providence , Rhode Island 02903 , United States.,Department of Engineering , Brown University , Providence , Rhode Island 02903 , United States
| | - Tannin A Schmidt
- Biomedical Engineering Department, School of Dental Medicine , University of Connecticut Health Center , 263 Farmington Avenue , Farmington , Connecticut 06030 , United States
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
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13
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Kobler JB, Tynan MA, Zeitels SM, Liss AS, Gianatasio MT, Morin AA, Schmidt TA. Lubricin/proteoglycan 4 detected in vocal folds of humans and five other mammals. Laryngoscope 2019; 129:E229-E237. [PMID: 30613972 DOI: 10.1002/lary.27783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2018] [Indexed: 12/28/2022]
Abstract
OBJECTIVES/HYPOTHESIS Lubricin/proteoglycan-4 (PRG4) lubricates connective tissues such as joints and tendon sheaths, enabling them to better withstand shearing and frictional forces during motion. We wondered whether PRG4 might play a role in phonation, as normal vocal folds withstand repetitive, high-velocity deformations remarkably well. As a first step, we tested whether PRG4 is expressed in vocal folds. STUDY DESIGN Laboratory study. METHODS Anatomical and molecular methods were applied to 47 larynges from humans, macaque (Macaca fascicularis), canines, pigs, calves, and rats. Immunohistochemistry (IHC), Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR) methods were used to test for the presence of PRG4. RESULTS In all species, the true vocal fold lamina propria (TVF-LP) was positive for PRG4 by IHC, whereas immunoreactivity of the false vocal fold was weak or absent, depending on the species. Human TVF-LP was strongly stained across all layers. Immunoreactivity was seen variably on the vocal fold surface and within the vocal fold epithelium, in the conus elasticus and thyroglottic ligament, and at the tip of vocal process. Western blots of four humans and six pigs demonstrated immunoreactivity at appropriate molecular weight. qRT-PCR of pig tissues confirmed PRG4 mRNA expression, which was highest in the TVF-LP. CONCLUSIONS PRG4 was found in phonatory tissues of six mammals. We suggest it might act as a lubricant within the lamina propria and possibly on the vocal fold surface, limiting phonation-related damage to vocal fold extracellular matrix and epithelium, and enhancing vocal efficiency by reducing internal friction (viscosity) within the vocal fold. LEVEL OF EVIDENCE NA Laryngoscope, 129:E229-E237, 2019.
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Affiliation(s)
- James B Kobler
- Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts, U.S.A.,Department of Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Monica A Tynan
- Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts, U.S.A
| | - Steven M Zeitels
- Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts, U.S.A.,Department of Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Andrew S Liss
- Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts, U.S.A.,Department of Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Maria T Gianatasio
- Cancer Center Histopathology Core, Massachusetts General Hospital, Boston, Massachusetts, U.S.A
| | - Alyssa A Morin
- Biomedical Engineering Department, University of Connecticut Health Center, Farmington, Connecticut, U.S.A
| | - Tannin A Schmidt
- Biomedical Engineering Department, University of Connecticut Health Center, Farmington, Connecticut, U.S.A
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14
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Das N, Schmidt TA, Krawetz RJ, Dufour A. Proteoglycan 4: From Mere Lubricant to Regulator of Tissue Homeostasis and Inflammation. Bioessays 2018; 41:e1800166. [DOI: 10.1002/bies.201800166] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/19/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Nabangshu Das
- Faculty of Kinesiology; University of Calgary; Calgary Alberta T2N4N1 Canada
| | - Tannin A. Schmidt
- Biomedical Engineering Department; School of Dental Medicine; University of Connecticut Health Center; Farmington CT 06030 USA
| | - Roman J. Krawetz
- Cell Biology and Anatomy; Cumming School of Medicine; University of Calgary; 3330 Hospital Drive NW Calgary Alberta T2N4N1 Canada
- McCaig institute for Bone and Joint Health; University of Calgary; Calgary Alberta T2N4N1 Canada
| | - Antoine Dufour
- McCaig institute for Bone and Joint Health; University of Calgary; Calgary Alberta T2N4N1 Canada
- Physiology & Pharmacology; Cumming School of Medicine; University of Calgary; Calgary Alberta T2N4N1 Canada
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15
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Samsom M, Korogiannaki M, Subbaraman LN, Sheardown H, Schmidt TA. Hyaluronan incorporation into model contact lens hydrogels as a built-in lubricant: Effect of hydrogel composition and proteoglycan 4 as a lubricant in solution. J Biomed Mater Res B Appl Biomater 2017; 106:1818-1826. [DOI: 10.1002/jbm.b.33989] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 08/11/2017] [Accepted: 08/28/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Michael Samsom
- Biomedical Engineering Graduate Program; University of Calgary; Calgary Alberta Canada
| | - Myrto Korogiannaki
- Faculty of Chemical Engineering; McMaster University; Hamilton Ontario Canada
| | - Lakshman N. Subbaraman
- Centre for Contact Lens Research, School of Optometry & Vision Science; University of Waterloo; Waterloo Ontario Canada
| | - Heather Sheardown
- Faculty of Chemical Engineering; McMaster University; Hamilton Ontario Canada
| | - Tannin A. Schmidt
- Biomedical Engineering Graduate Program; University of Calgary; Calgary Alberta Canada
- Faculty of Kinesiology; University of Calgary; Calgary Alberta Canada
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16
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Degradation of proteoglycan 4/lubricin by cathepsin S: Potential mechanism for diminished ocular surface lubrication in Sjögren's syndrome. Exp Eye Res 2017; 161:1-9. [DOI: 10.1016/j.exer.2017.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 04/21/2017] [Accepted: 05/19/2017] [Indexed: 11/15/2022]
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17
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Samsom M, Iwabuchi Y, Sheardown H, Schmidt TA. Proteoglycan 4 and hyaluronan as boundary lubricants for model contact lens hydrogels. J Biomed Mater Res B Appl Biomater 2017; 106:1329-1338. [DOI: 10.1002/jbm.b.33895] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/07/2017] [Accepted: 03/28/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Michael Samsom
- Biomedical Engineering Graduate ProgramUniversity of CalgaryCalgary AB Canada
| | - Yuno Iwabuchi
- Faculty of KinesiologyUniversity of CalgaryCalgary AB Canada
| | - Heather Sheardown
- Department of Chemical EngineeringMcMaster UniversityHamilton ON Canada
| | - Tannin A. Schmidt
- Biomedical Engineering Graduate ProgramUniversity of CalgaryCalgary AB Canada
- Faculty of KinesiologyUniversity of CalgaryCalgary AB Canada
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18
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Ludwig TE, Hunter MM, Schmidt TA. Cartilage boundary lubrication synergism is mediated by hyaluronan concentration and PRG4 concentration and structure. BMC Musculoskelet Disord 2015; 16:386. [PMID: 26666513 PMCID: PMC4678696 DOI: 10.1186/s12891-015-0842-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/02/2015] [Indexed: 11/26/2022] Open
Abstract
Background Proteoglycan 4 (PRG4) and hyaluronan (HA) are key synovial fluid constituents that contribute synergistically to cartilage boundary lubrication; however, the effects of their concentrations as well as their structure, both of which can be altered in osteoarthritis, on this functional synergism are unknown. The objectives of this study were to evaluate cartilage boundary lubricating ability of 1) PRG4 + HA in solution at constant HA concentration in a range of PRG4 concentrations, 2) constant PRG4 concentration in a range of HA concentrations, 3) HA + reduced/alkylated (R/A) PRG4, and 4) hylan G-F 20 + PRG4. Methods Static and kinetic friction coefficients (μstatic,Neq, <μkinetic,Neq>) were measured using a previously characterized cartilage-cartilage boundary mode friction test for the following concentrations of purified PRG4 and HA: Test 1: HA (1.5 MDa, 3.3 mg/mL) + PRG4 from 4.5 – 1500 μg/mL; Test 2: PRG4 (450, 150, 45 μg/mL) + HA (1.5 MDa) from 0.3 – 3.3 mg/mL. Test 3: hylan G-F 20 (3. 3 mg/mL) + PRG4 (450 μg/mL). Test 4: HA (3.3 mg/mL) + R/A PRG4 (450 μg/mL). ANOVA was used to compare lubricants within (comparing 6 lubricants of interest) and between (comparing 3 lubricants of interest) test sequences, with Tukey and Fishers post-hoc testing respectively. Results This study demonstrates that both PRG4 and HA concentration, as well as PRG4 disulfide-bonded structure, can alter the cartilage boundary lubricating ability of PRG4 + HA solutions. The boundary lubricating ability of high MW HA + PRG4 solutions was limited by very low concentrations of PRG4. Decreased concentrations of high MW HA also limited the cartilage boundary lubricating ability of HA + PRG4 solutions, with the effect exacerbated by low PRG4 concentrations. The reduction of friction by addition of PRG4 to a cross-linked HA viscosupplement product, but not with addition of R/A PRG4 to HA, is consistent with a non-covalent mechanism of interaction where tertiary and quaternary PRG4 structure are important. Conclusions Collectively, these results demonstrate that deficiency of either or both PRG4 and HA, or alterations in PRG4 structure, may be detrimental to SF cartilage boundary lubricating function. This study provides further insight into the nature of cartilage boundary lubrication and advancement towards potential formulation of new intra-articular biotherapeutic treatments for osteoarthritis using PRG4 ± HA.
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Affiliation(s)
- Taryn E Ludwig
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Canada.
| | - Miles M Hunter
- Faculty of Kinesiology, University of Calgary, Calgary, Canada.
| | - Tannin A Schmidt
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Canada. .,Faculty of Kinesiology, University of Calgary, Calgary, Canada.
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