Characterization and Localization of Citrullinated Proteoglycan Aggrecan in Human Articular Cartilage

Glant, Tibor T.; Ocskó, Tímea; Markovics, Adrienn; Szekanecz, Zoltán; Katz, Robert S.; Rauch, Tibor A.; Mikecz, Katalin

doi:10.1371/journal.pone.0150784

Cited by 14 publications

(17 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies have reported immunogenic aggrecan peptides and demonstrated responses to citrullinated aggrecan in samples from patients with RA . To corroborate the relevance of citrullinated aggrecan epitope–specific T cells, we compared the frequency of T cells specific for Cit‐aggrecan 225 and Cit‐aggrecan 553 in RA patients and healthy controls with DRB1*04:01 haplotypes.…”

Section: Resultsmentioning

confidence: 95%

“…IgM depletion was verified by anti‐IgM Western blotting. For enzyme‐linked immunosorbent assay (ELISA), wells of 96‐well ELISA plates (Nunc) were coated overnight with recombinant human aggrecan G1 or citrullinated recombinant human aggrecan G1 domain (0.2 μg/well each) in 100 μl/well of 0.15 M sodium carbonate buffer (pH 9.6) at room temperature . Unbound antigen was removed by washing with horseradish peroxidase (HRP) wash buffer (Inova Diagnostics).…”

Section: Methodsmentioning

confidence: 99%

“…Emerging data suggest that the matrix protein proteoglycan aggrecan is recognized as a citrullinated antigen . Aggrecan is an abundant component of extracellular matrix within the joints (along with proteins such as tenascin‐C and type II collagen) and has been conclusively shown to be citrullinated in human articular cartilage . The presence of aggrecan fragments has been documented within synovial fluid and is reported to increase with age .…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, immunization with aggrecan was shown to induce arthritis in murine models . Levels of autoantibodies to citrullinated epitopes within the G1 domain are elevated in RA but not in osteoarthritis, indicating that such antibodies are specifically associated with autoimmunity rather than merely accompanying joint damage . Citrullinated CD4+ T cell epitopes from aggrecan have been described, and elevated responses to some were shown to be associated with RA .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Citrullinated Aggrecan Epitopes as Targets of Autoreactive CD4+ T Cells in Patients With Rheumatoid Arthritis

Rims

Uchtenhagen

Kaplan

et al. 2019

Arthritis & Rheumatology

Self Cite

View full text Add to dashboard Cite

Objective. Recognition of citrullinated antigens such as vimentin, fibrinogen, and α-enolase is associated with rheumatoid arthritis (RA). Emerging data suggest that the matrix protein aggrecan is also recognized as a citrullinated antigen. This study was undertaken to directly visualize Cit-aggrecan-specific T cells and characterize them in patients with RA.Methods. Citrullinated aggrecan peptides with likely DRB1 * 04:01 binding motifs were predicted using a previously published scanning algorithm. Peptides with detectable binding were assessed for immunogenicity by HLA tetramer staining, followed by single cell cloning. Selectivity for citrullinated peptide was assessed by tetramer staining and proliferation assays. Ex vivo tetramer staining was then performed to assess frequencies of aggrecan-specific T cells in peripheral blood. Finally, disease association was assessed by comparing T cell frequencies in RA patients and controls and correlating aggrecan-specific T cells with levels of aggrecan-specific antibodies.Results. We identified 6 immunogenic peptides, 2 of which were the predominant T cell targets in peripheral blood. These 2 epitopes were citrullinated at HLA binding residues and shared homologous sequences. RA patients had significantly higher frequencies of Cit-aggrecan-specific T cells than healthy subjects. Furthermore, T cell frequencies were significantly correlated with antibodies against citrullinated aggrecan.Conclusion. Our findings indicate that T cells that recognize citrullinated aggrecan are present in patients with RA and correlate with antibodies that target this same antigen. Consequently, aggrecan-specific T cells and antibodies are potentially relevant markers that could be used to monitor patients with RA or at-risk subjects.

show abstract

Section: Resultsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Citrullinated Aggrecan Epitopes as Targets of Autoreactive CD4+ T Cells in Patients With Rheumatoid Arthritis

Rims

Uchtenhagen

Kaplan

et al. 2019

Arthritis & Rheumatology

Self Cite

View full text Add to dashboard Cite

show abstract

“…In RA, multiple proteins are citrullinated, especially in target organs of the disease, primarily the synovium but also in the lungs (20) and in myocardial tissue (21). In the RA joints, citrullinated fibrin is not only particularly abundant (22) but also several other citrullinated proteins including vimentin and aggrecan (23) are detectable. Citrullination is not an RA-specific process, and citrullinated proteins are present in several other inflammatory processes including the inflamed skeletal muscle tissue in myositis (24) and the synovium of spondyloarthritis patients (25).…”

Section: Neutrophils Citrullination and Netosis In Ramentioning

confidence: 99%

NETosis as Source of Autoantigens in Rheumatoid Arthritis

et al. 2016

View full text Add to dashboard Cite

In neutrophils (but also in eosinophils and in mast cells), different inflammatory stimuli induce histone deimination, chromatin decondensation, and NET formation. These web-like structures that trap and kill microbes contain DNA, cationic granule proteins, and antimicrobial peptides, but the most abundant proteins are core histones. Histones contained in NETs have been deiminated, and arginines are converted in citrullines. While deimination is a physiological process amplified in inflammatory conditions, only individuals carrying genetic predisposition to develop rheumatoid arthritis (RA) make antibodies to deiminated proteins. These antibodies, collectively identified as anti-citrullinated proteins/peptides antibodies (ACPA), react with different deiminated proteins and display partially overlapping specificities. In this paper, we will summarize current evidence supporting the role of NETosis as critical mechanism in the breach of tolerance to self-antigens and in supporting expansion and differentiation of autoreactive cells. In fact, several lines of evidence connect NETosis with RA: RA unstimulated synovial fluid neutrophils display enhanced NETosis; sera from RA patients with Felty’s syndrome bind deiminated H3 and NETs; a high number of RA sera bind deiminated H4 contained in NETs; human monoclonal antibodies generated from RA synovial B cells decorate NETs and bind deiminated histones. In RA, NETs represent on one side an important source of autoantigens bearing posttranslational modifications and fueling the production of ACPA. On the other side, NETs deliver signals that maintain an inflammatory milieu and contribute to the expansion and differentiation of ACPA-producing B cells.

show abstract

Serologic Biomarkers of Progression Toward Diagnosis of Rheumatoid Arthritis in Active Component Military Personnel

Loza

Nagpal

Cole

et al. 2022

Arthritis & Rheumatology

View full text Add to dashboard Cite

Objective. To identify a panel of serum biomarkers that could specifically identify imminent cases of rheumatoid arthritis (RA) before diagnosis.Methods. Serum samples were collected at 4 time points from active component US military personnel, including 157 anti-citrullinated protein antibody (ACPA)-seropositive and 50 ACPA-seronegative RA subjects, 100 reactive arthritis (ReA) subjects, and 76 healthy controls. The cohorts were split into 2 phases, with samples tested on independent proteomic platforms for each phase. Classification models of RA diagnosis based on samples obtained within 6 months prior to diagnosis were developed both in univariate analyses and by multivariate random forest modeling of training sample sets and testing sample sets from each phase.Results. Increases in serum analytes, including C-reactive protein levels, serum amyloid A, and soluble programmed cell death 1 (PD-1), were observed in seropositive RA subjects at the time point closest to diagnosis, up to several years before diagnosis. Only a small fraction of RA subjects had levels above the 95th percentile of healthy control levels until the time period within 6 months of diagnosis. For classification of RA diagnosis using samples obtained within 6 months prior to diagnosis, soluble PD-1 provided superior specificity compared to ReA cases (>89%), with a sensitivity of 48% for RA classification. An 8-analyte model provided superior sensitivity (69%), with comparable specificity relative to ReA (>82%). Conclusion.Our findings demonstrate that imminent RA diagnosis could be classified with high specificity, relative to healthy controls and ReA cases, using a panel of cytokines measured in serum samples collected within 6 months before actual diagnosis.The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, the Department of Veterans Affairs, nor the US government. This is a US government work. There are no restrictions on its use. There were no financial conflicts of interests among any of the authors.Some authors are employees of the US government. This work was prepared as part of their official duties.

show abstract

Characterization and Localization of Citrullinated Proteoglycan Aggrecan in Human Articular Cartilage

Cited by 14 publications

References 45 publications

Citrullinated Aggrecan Epitopes as Targets of Autoreactive CD4+ T Cells in Patients With Rheumatoid Arthritis

Citrullinated Aggrecan Epitopes as Targets of Autoreactive CD4+ T Cells in Patients With Rheumatoid Arthritis

NETosis as Source of Autoantigens in Rheumatoid Arthritis

Serologic Biomarkers of Progression Toward Diagnosis of Rheumatoid Arthritis in Active Component Military Personnel

Contact Info

Product

Resources

About