scholarly journals FRI0005 DIVERSITY OF ANTI-CITRULLINATED PROTEIN ANTIBODY COMPOSITIONS INFLUENCE SYNOVIAL FIBROBLAST REACTIVITY

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 573.2-574
Author(s):  
M. Sun ◽  
B. Réthi ◽  
A. Krishnamurthy ◽  
V. Joshua ◽  
A. Circiumaru ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Monoclonal Antibodies ◽  
Synovial Tissue ◽  
Trichostatin A ◽  
Synovial Fibroblasts ◽  
Cross Reactivity ◽  
Anacardic Acid ◽  
Cellular Targets ◽  
Fibroblast Migration ◽  
Citrullinated Protein

Background:Anti-citrullinated protein antibodies (ACPAs) play an important role in rheumatoid arthritis (RA) pathogenesis. We hypothesized that the effect of these antibodies is mediated by their binding to synovial fibroblasts and inducing an increased mobility of fibroblasts1.Objectives:In our study, we analyzed and compared fibroblast modulation by ACPA pools obtained from different patients or by a set of monoclonal ACPAs with different fine specificity that were obtained from different tissue sites.Methods:Synovial fibroblasts were isolated from RA patients synovial tissue biopsies. Individual polyclonal ACPA and control IgGs were purified from sera of four ACPA-positive RA patients by affinity purification on protein G and CCP-2 columns. Monoclonal antibodies were derived from memory B cell isolated from blood2, synovial fluid or bronchoalveolar lavage of RA patients. Whole antibodies and F(ab’)2 fragments were tested in fibroblast migration using IncuCyte live-cell analysis. Blocking experiments were performed with soluble citrullinated proteins in SF migration. Cross-reactivity of the antibodies to citrullinated and acetylated epitopes was tested using PAD inhibitors (Cl-amidine and GSK199), histone acetyltransferases (anacardic acid) and deacetylases (trichostatin A). Binding patterns of monoclonal ACPAs, both whole and F(ab’)2 fragments were analyzed in synovial biopsies obtained from both healthy donors and RA patients.Results:Three out of four tested individual ACPA were able to promote fibroblast migration. Five out of nine tested monoclonal ACPAs stimulated fibroblast migration. One of these antibodies, clone 1325:01B09 is characterized by cross-reactivity to citrullinated, homocitrullinated and acetylated targets. The effect of 1325:01B09 on fibroblast migration was completely abolished by Cl-amidine or by pre-incubating the antibody with citrullinated fibrinogen or histone but not citrullinated enolase or vimentin. Despite the cross-reactivity to acetylated epitopes, neither anacardic acid nor trichostatin A could modulate the 1325:01B09 effect on fibroblast migration. F(ab’)2 fragments of this antibody stimulated fibroblast migration and labelled podoplanin-positive fibroblasts in inflamed RA synovium similarly to the intact antibody, indicating an Fc-independent effect.Conclusion:The effect on fibroblast mobility was likely to be mediated by binding to citrullinated epitopes but not through Fc receptors. Detection of fibroblast modulating ACPAs in majority of RA patients indicated that fibroblasts might be key cellular targets in disease pathogenesis, although individual variability might exist in the composition of ACPA cellular targets.References:[1]Sun M, Rethi B, Krishnamurthy A, et al. Anticitrullinated protein antibodies facilitate migration of synovial tissue-derived fibroblasts. Ann Rheum Dis 2019;78(12):1621-31. doi: 10.1136/annrheumdis-2018-214967 [published Online First: 2019/09/05][2]Amara K, Lena Israelsson, Ragnhild Stålesen, et al. A Refined Protocol for Identifying Citrulline-specific Monoclonal Antibodies from Single Human B Cells from Rheumatoid Arthritis Patient Material. Bio-protocol 2019;9(16)Disclosure of Interests:Meng Sun: None declared, Bence Réthi: None declared, Akilan Krishnamurthy: None declared, Vijay Joshua: None declared, Alexandra Circiumaru: None declared, Marianne Engström: None declared, Caroline Grönwall: None declared, Vivianne Malmström Grant/research support from: VM has had research grants from Janssen Pharmaceutica, Khaled Amara: None declared, Lars Klareskog: None declared, Heidi Wähämaa: None declared, Anca Catrina: None declared

scholarly journals Mechanism of miR-218-5p in autophagy, apoptosis and oxidative stress in rheumatoid arthritis synovial fibroblasts is mediated by KLF9 and JAK/STAT3 pathways

2021 ◽  
pp. jim-2020-001437
Author(s):  
Ming Chen ◽  
Minghui Li ◽  
Na Zhang ◽  
Wenwen Sun ◽  
Hui Wang ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Oxidative Stress ◽  
Signaling Pathway ◽  
Synovial Tissue ◽  
Synovial Fibroblasts ◽  
Reverse Transcription Pcr ◽  
Stat3 Signaling ◽  
Stat3 Signaling Pathway ◽  
Interfering Rna ◽  
And Oxidative Stress

This study was aimed to investigate the effects of miR-218-5p on the proliferation, apoptosis, autophagy, and oxidative stress of rheumatoid arthritis synovial fibroblasts (RASFs), and the related mechanisms. Quantitative reverse transcription–PCR showed that the expression of miR-218-5p in rheumatoid arthritis synovial tissue was significantly higher than that in healthy synovial tissue. Compared with healthy synovial fibroblasts, miR-218-5p expression was obviously upregulated in RASFs, while KLF9 protein expression was markedly downregulated. Mechanistically, miR-218-5p could directly bind to the 3′ untranslated region of KLF9 to inhibit the expression of KLF9. Additionally, transfection of miR-218-5p small interfering RNA (siRNA) inhibited the proliferation but promoted apoptosis and autophagy of RASFs. Simultaneously, miR-218-5p silencing reduced reactive oxygen species and malondialdehyde levels and increased superoxide dismutase and glutathione peroxidase activity to improve oxidative stress in RASFs. More importantly, the introduction of KLF9 siRNA reversed the effects of miR-218-5p siRNA transfection on RASF proliferation, apoptosis, autophagy, and oxidative stress. What is more, silencing miR-218-5p inhibited the activation of JAK2/STAT3 signaling pathway by targeting KLF9. Collectively, knockdown of miR-218-5p could regulate the proliferation, apoptosis, autophagy and oxidative stress of RASFs by increasing the expression of KLF9 and inhibiting the activation of the JAK2/STAT3 signaling pathway, which may provide a potential target for the mechanism research of RA.

Hierarchy in the Avidity and Cross-reactivity of Anti-citrullinated Protein Antibodies in the Serum of Patients With Rheumatoid Arthritis

2020 ◽  
Author(s):  
Akihisa Haraguchi ◽  
Hisakata Yamada ◽  
Takahide Sakuragi ◽  
Tomomi Tsuru ◽  
Masakazu Kondo ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Immune Response ◽  
Serum Antibody ◽  
Cross Reactivity ◽  
Sodium Thiocyanate ◽  
Fine Specificity ◽  
Thiocyanate Solution ◽  
Citrullinated Protein ◽  
Citrullinated Peptide ◽  
Substantial Extent

Abstract BackgroundFine specificity of anti-citrullinated protein antibodies (ACPAs), in which cross-reactivity exists, varies among patients with rheumatoid arthritis (RA), but it is unclear whether the mechanism of ACPA production is same or different among individuals. Since avidity of serum antibody reflects the direction of immune response, we compared the levels of avidity and cross-reactivity between various ACPAs in a cohort of RA patient.MethodsSera from 180 RA patients positive for anti-cyclic citrullinated peptide (CCP) 2 antibody were screened for positivity of antibodies against CCP1, and citrullnated fibrinogen (cFib), enolase (cEno), and vimentin (cVim) peptides. Avidity of the four ACPAs, and some autoantibodies and antibodies against foreign antigens was determined by an elution assay using sodium thiocyanate solution. Cross-reactivity between different ACPAs was estimated by measuring the inhibition of binding by competitor peptides. ResultsThe prevalence of anti-CCP1, anti-cFib, anti-cEno, and anti-cVim antibodies in the anti-CCP2-positive RA cohort were 37.7%, 38.3%, 15.6%, and 23.9%, respectively. The avidity of ACPAs, except for anti-cVim antibody, was significantly lower than that of antibodies against foreign antigens, while there was a large variety in the avidity of other autoantibodies. At individual levels, the avidity of anti-cVim was significantly higher than that of other ACPAs, and there was a significant correlation in the avidity of anti-CCP and anti-cFib antibodies. Substantial extent of cross-reactivity was seen between different ACPAs, which also showed a fixed hierarchy.ConclusionThe fixed hierarchy in the avidity and cross-reactivity between different ACPAs suggests that the mechanism underlying ACPA production is common to all RA patients. Presence of a dominant antigen that induces whole ACPA response is speculated.

scholarly journals Different classes of anti-modified protein antibodies are induced on exposure to antigens expressing only one type of modification

2019 ◽  
Vol 78 (7) ◽  
pp. 908-916 ◽  
Author(s):  
Arieke Suzanna Berendina Kampstra ◽  
Jacqueline Stephanie Dekkers ◽  
Mikhail Volkov ◽  
Annemarie L Dorjée ◽  
Lise Hafkenscheid ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
B Cell ◽  
Cell Response ◽  
Cross Reactivity ◽  
Single Type ◽  
Mutual Relationship ◽  
Post Translational Modifications ◽  
Modified Proteins ◽  
Relationship Of ◽  
Citrullinated Protein

ObjectivesAutoantibodies against post-translationally modified proteins (anti-modified protein antibodies or AMPAs) are a hallmark of rheumatoid arthritis (RA). A variety of classes of AMPAs against different modifications on proteins, such as citrullination, carbamylation and acetylation, have now been described in RA. At present, there is no conceptual framework explaining the concurrent presence or mutual relationship of different AMPA responses in RA. Here, we aimed to gain understanding of the co-occurrence of AMPA by postulating that the AMPA response shares a common ‘background’ that can evolve into different classes of AMPAs.MethodsMice were immunised with modified antigens and analysed for AMPA responses. In addition, reactivity of AMPA purified from patients with RA towards differently modified antigens was determined.ResultsImmunisation with carbamylated proteins induced AMPAs recognising carbamylated proteins and also acetylated proteins. Similarly, acetylated proteins generated (autoreactive) AMPAs against other modifications as well. Analysis of anti-citrullinated protein antibodies from patients with RA revealed that these also display reactivity to acetylated and carbamylated antigens. Similarly, anti-carbamylated protein antibodies showed cross-reactivity against all three post-translational modifications.ConclusionsDifferent AMPA responses can emerge from exposure to only a single type of modified protein. These findings indicate that different AMPA responses can originate from a common B-cell response that diversifies into multiple distinct AMPA responses and explain the presence of multiple AMPAs in RA, one of the hallmarks of the disease.

scholarly journals The Autophagy Level Is Increased in the Synovial Tissues of Patients with Active Rheumatoid Arthritis and Is Correlated with Disease Severity

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Li Zhu ◽  
Huaizhou Wang ◽  
Yu Wu ◽  
Zhengwen He ◽  
Yanghua Qin ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Synovial Tissue ◽  
Active Rheumatoid Arthritis ◽  
Synovial Fibroblasts ◽  
Serum Levels ◽  
Serum Markers ◽  
Effector Cells ◽  
Joint Replacement Surgery ◽  
Replacement Surgery ◽  
Synovial Tissues

Rheumatoid arthritis (RA) is a complex and not fully understood autoimmune disease associated with multijoint damage. The main effector cells, the synovial fibroblasts, are apoptosis resistant and hyperplastic which indicate that autophagy level is high in synovial tissue. Real-time PCR, immunocytochemistry, and western blotting were used in this paper to study the autophagy status of the synovial tissues obtained from RA and OA patients at the time of joint replacement surgery. We further evaluated the correlation between autophagy levels with RA activity-associated serum markers with SPSS. The results showed that the expression levels (both in mRNA and in protein level) of autophagy-related proteins (belcin1, Atg5, and LC3) in the synovial tissue of patients with active rheumatoid arthritis (n=20) were significantly higher than those in OA patients (n=16). We further showed that the LC3-II/β-actin relative gray value was strongly correlated with the serum levels of several RA activity-related markers: CRP, ESR, CCP, and RF. Our results indicate that evaluating the autophagy level of synovial biopsies might be a useful way to diagnose RA and to estimate the disease activity. Reducing the expression level of autophagy-related genes might become a new therapeutic target for active rheumatoid arthritis.

Multiple antibody reactivities to citrullinated antigens in sera from patients with rheumatoid arthritis: association with HLA-DRB1 alleles

2008 ◽  
Vol 68 (5) ◽  
pp. 736-743 ◽  
Author(s):  
O Snir ◽  
M Widhe ◽  
C von Spee ◽  
J Lindberg ◽  
L Padyukov ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Shared Epitope ◽  
Type Ii Collagen ◽  
Cross Reactivity ◽  
Igg Antibodies ◽  
Serum Samples ◽  
Hla Dr ◽  
Citrullinated Proteins ◽  
The Relationship ◽  
Citrullinated Protein

Background:Autoantibodies to cyclic citrullinated peptides (anti-CCP) are present in most patients with rheumatoid arthritis (RA), and associate with HLA-DRB1 shared epitope (SE) alleles.Objective:To investigate reactivities of anti-CCP to various citrullinated proteins/peptides, which represent potential autoantigens in RA, and to examine the relationship between such antibodies, and their association with genetic variants within HLA-DRB1 SE alleles.Methods:Serum samples from 291 patients with established RA and 100 sex- and age-matched healthy subjects were included in this study. Sera were first analysed for presence of anti-CCP antibodies and further for IgG and IgA antibodies towards candidate autoantigens in both their native and citrullinated form including: fibrinogen, α-enolase peptide-1 and the C1-epitope of type II collagen (C1III). Antibody specificity was confirmed by cross-reactivity tests. HLA-DR genotyping was performed.Results:72% of patients with RA were anti-CCP positive. Among the candidate autoantigens examined, IgG antibodies to citrullinated fibrinogen were found in 66% of patients’ sera and in 41% for both citrullinated α-enolase peptide-1 and citrullinated C1III. These antibodies were mainly seen in the anti-CCP-positive patient group; they were specific for their respective antigen and displayed limited cross reactivity. IgA responses were also detected, but less frequently than IgG. Anti-CCP and anti-citrullinated protein antibodies were associated with HLA-DRB1*04 rather than with HLA-DRB1*01 alleles.Conclusions:Antibodies directed against several citrullinated antigens are present in CCP-positive RA, with many patients displaying multireactivity. All specific reactivities were primarily associated with the HLA-DRB1*04 alleles, suggesting common pathways of anti-citrulline immunity.

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