Antigens In Rheumatoid Arthritis Research Articles

Study of some genetic and molecular markers for some rheumatoid arthritis patients in Iraq.

Rheumatoid arthritis is an autoimmune disorder, and genetic factors strongly contribute to a genetic predisposition to developing the disease. This study evaluated the genetic and molecular indicators of some Iraqi patients with rheumatoid arthritis. The study included (100) patients with rheumatoid arthritis with (100) healthy individuals who attended Al-Hussain General Teaching Hospital, Department of Arthritis and Joints Centre, al Blood Bank in Baghdad for the period from the beginning of January 2022 until the end of March 2022. The patients were diagnosed under the supervision of medical committees specialized in joint diseases. The human leukocyte antigen is one of the essential genetic factors in regulating the immune response, as these antigens contribute to the susceptibility to disease. Human leukocyte antigen (HLA) class II (Class-II- HLA-DR, -DQ) was genotyped using lymphocytotoxicity assay and PCR-SSP method. The results showed that there was a significant increase in the recurrence of human leukocyte antigens (DR4 R53) in rheumatoid arthritis patients compared to the healthy ones, as well as an increase in the recurrence of human leukocyte antigens (HLA-DQ3) with a significant difference in rheumatoid arthritis patients compared to the healthy ones. Regarding HLA-DRB1 and -DQB1 alleles, it was found that there was a significant increase in the frequency of HLA-DRB1*04 (01-22, not 0415) compared to healthy controls, while the percentage of HLA-DRB1*0701 alleles was less frequent in patients compared to healthy controls. Moreover, the frequency of HLADQB1*03(02,07) alleles was high in the patients compared to the healthy ones, while HLA-DQB1*0303 showed a highly significant difference in the healthy group compared to the patients. Keywords: Rheumatoid arthritis, genetic factors, HLA-DRB1, -DQB1 alleles, PCR.

Anti-Citrullinated Protein Antibody Reactivity towards Neutrophil-Derived Antigens: Clonal Diversity and Inter-Individual Variation.

Why the adaptive immune system turns against citrullinated antigens in rheumatoid arthritis (RA) and whether anti-citrullinated protein antibodies (ACPAs) contribute to pathogenesis are questions that have triggered intense research, but still are not fully answered. Neutrophils may be crucial in this context, both as sources of citrullinated antigens and also as targets of ACPAs. To better understand how ACPAs and neutrophils contribute to RA, we studied the reactivity of a broad spectrum of RA patient-derived ACPA clones to activated or resting neutrophils, and we also compared neutrophil binding using polyclonal ACPAs from different patients. Neutrophils were activated by Ca2+ ionophore, PMA, nigericin, zymosan or IL-8, and ACPA binding was studied using flow cytometry and confocal microscopy. The roles of PAD2 and PAD4 were studied using PAD-deficient mice or the PAD4 inhibitor BMS-P5. ACPAs broadly targeted NET-like structures, but did not bind to intact cells or influence NETosis. We observed high clonal diversity in ACPA binding to neutrophil-derived antigens. PAD2 was dispensable, but most ACPA clones required PAD4 for neutrophil binding. Using ACPA preparations from different patients, we observed high patient-to-patient variability in targeting neutrophil-derived antigens and similarly in another cellular effect of ACPAs, the stimulation of osteoclast differentiation. Neutrophils can be important sources of citrullinated antigens under conditions that lead to PAD4 activation, NETosis and the extrusion of intracellular material. A substantial clonal diversity in targeting neutrophils and a high variability among individuals in neutrophil binding and osteoclast stimulation suggest that ACPAs may influence RA-related symptoms with high patient-to-patient variability.

The dimeric form of HLA-G molecule is associated with the response of early rheumatoid arthritis (ERA) patients to methotrexate.

A growing body of evidence indicates a possible involvement of HLA (human leukocyte antigen)-G antigens in rheumatoid arthritis (RA), mainly in the HLA-G dimeric isoform, the most active HLA-G form with the strongest immunosuppression, that showed an excellent anti-inflammatory effect in collagen-induced arthritis model mice. However, the relevance of HLA-G dimers in RA response to methotrexate (MTX) treatment is still unknown. We analyzed the HLA-G dimers' amount in plasma samples from early rheumatoid arthritis (ERA) patients before MTX therapy and evaluated the role of these molecules as biomarker of the different response to the treatment. Plasma sHLA-G levels were detected by ELISA, and HLA-G dimeric and monomeric forms were revealed by Western blot in 12 MTX responder (reaching DAS28 remission <2.6) and 8 MTX non-responder (DAS28 ≥5.1) patients before the therapy. The response to MTX was evaluated after 6months of treatment. All ERA patients reaching remission showed higher plasma sHLA-G levels and the 78kDa HLA-G dimeric form. Unresponsive ERA patients were characterized by lower plasma sHLA-G levels, and only one patient presented the 78kDa HLA-G dimeric form (DAS28 5.1). Our preliminary results support the hypothesis that in ERA patients, sHLA-G and, in particular, the presence of the dimeric form in plasma samples before MTX therapy could be an a priori biomarker for the response to MTX treatment.

Sequential high-content profiling of the IgG-autoantibody repertoire reveals novel antigens in rheumatoid arthritis.

BackgroundThe aim was to identify novel diagnostic autoantibody candidates for rheumatoid arthritis (RA) by comprehensive screening for autoreactivity.MethodWe incubated 5892 recombinant proteins coupled to fluorescent beads, with patients’ sera for the detection of IgG-autoantibodies in three independent patient cohorts: A (n = 72 patients with established RA); B/B- (n = 116 patients with early RA (B) and n = 51 CCP-negative patients with early RA from B (B-)); and C (n = 184 patients with early seronegative RA), in comparison to matched healthy controls. Intersects of significantly increased autoantibodies as determined by the Mann-Whitney test were sought.ResultScreening of 5892 antigens in RA cohorts A and B, or the seronegative cohorts B- and C revealed intersects of 23 and 13 significantly increased autoantibodies, respectively. Reactivity to three antigens was increased in all cohorts tested: N-acetylglucosamine-1-phosphate transferase, gamma subunit (GNPTG), heterogeneous nuclear ribonucleoprotein A1-like 2 (HNRNPA1), and insulin-like growth factor binding protein 2 (IGFBP2).ConclusionsComprehensive sequential screening for autoantibodies reveals novel candidates for diagnostic markers in both seropositive and seronegative RA and suggests new fields of research into the pathogenesis of RA.

Mutations in the Fc-region of IgG from synovial fluids of patients with rheumatoid arthritis

AbstractRheumatoid arthritis an antigen-driven autoimmune disease and the eliciting antigens are unknown. They should be present in immune complexes of synovial fluids. The immune complexes were isolated from synovial fluids of patients with rheumatoid arthritis and analyzed by polyacrylamide gel electrophoresis and Western blotting. Immune complexes contained IgG as major protein. The antibodies dissociated at pH 2.5 and self-aggregated upon neutralization. In ELISA assays, they had the highest specificity to homologous IgG, less to normal IgG and lowest of heterologous arthritic IgG confirming earlier results that altered IgG structures were antigenic. Sequencing of the Fc-regions revealed mutations in all patients analyzed. Therefore, mutations within the Fc-regions of IgG could be antigens in rheumatoid arthritis. We propose that methods should be developed to prove this hypothesis.

Peripheral Blood Mononuclear Cells’ Proliferative Response to Human Parvovirus B19 Antigens in Patients with Rheumatoid Arthritis / Reimatoīdā Artrīta Slimnieku Perifēro Asiņu Mononukleāro Šūnu Proliferativā Atbilde Uz Cilvēka Parvovīrusa B19 Antigēniem

Abstract This study aimed to determine peripheral blood mononuclear cells’ (PBMC) proliferative response to parvovirus B19 (B19) antigens in rheumatoid arthritis (RA) patients and possible changes in proliferative response due to chemotherapy. Serum and blood samples of 52 RA patients and 25 sex and age matched healthy individuals were examined for the presence of anti-B19 IgG and IgM class antibodies and virus specific DNA sequence by the recomLine B19 test and nested polymerase chain reaction, respectively. The PBMC proliferative activity was estimated on the 3rd and 6th day of PBMC cultivation in the presence of virus and B19 VP1/VP2 peptide, using thymidine incorporation assay. On the 3rd day, PBMC response to B19 antigens was detected in 74.1% RA patients with active, in 44.8% - with remote and in 40% - with latent stage of persistent B19 infection, while in the control group the response was observed only in two individuals with active viral infection. On the 6th day, the response was found in 50% RA patients with active, 68.9% - with remote and in 80% - with latent stage of latent persistent infection as well as in 41.1% remotely infected control individuals. The highest PBMC mean stimulation indices were detected in the RA patients and control persons with active infection as well as in RA patients with latent stage of persistent viral infection. On the 3rd and 6th day, strong proliferative response was significantly more frequently observed in RA patients not receiving methotrexate treatment, compared to the patients receiving methotrexate treatment in different combinations with other drugs. RA patients had more frequent and faster response to B19 antigens than apparently healthy persons.

Disease-Specific and Common HLA and Non-HLA Genetic Markers in Susceptibility to Rheumatoid Arthritis, Type 1 Diabetes Mellitus and Multiple Sclerosis

Autoimmune diseases cause numerous health and social problems throughout the world. The common spectrum of autoimmune diseases affect the majority of tissues within the body, including pancreatic beta cells in type 1 diabetes (T1DM), myelin surrounding nerve axons in Multiple sclerosis (MS) and synovial joint antigens in Rheumatoid Arthritis (RA). The diseases are likely caused by a complex interaction between multiple HLA- and non- HLA related genes and environmental factors. The well documented co-clustering of autoimmune diseases within families and individuals, together with apparent sharing of number risk genes between the diseases suggests at least some common mechanisms of autoimmune development.

Correlación de la respuesta a antígenos de Mycobacterium tuberculosis y la prueba cutánea tuberculina en pacientes con artritis reumatoide

Rheumatoid arthritis patients under treatment with anti-TNF-α are at a high risk of developing active tuberculosis, and therefore, screening for latent tuberculosis infection is recommended before anti-TNF-α therapy. To compare the tuberculin test and IFNγ production induced by culture filtrate proteins(CFPs) and Mycobacterium tuberculosis-specific CFP-10 antigens in rheumatoid arthritis patients. An analytic transversal study was conducted in rheumatoid arthritis patients treated at Hospital Universitario San Vicente Fundación between January and December 2007. IFNγ production in response to CFPs and CFP-10 was measured in the supernatants of whole blood cultures and evaluated for correlations with tuberculin reactivity. The degree of concordance between both tests was also established. Forty-five patients were included, of which 14 (31.1%) had a tuberculin reaction of ≥10 mm of induration, 9 (20%) produced IFNγ in response to CFP-10, and 7 were positive for both tests. The correlation between tests was r=0.53 (IC 95%:0.28-0.72), and the global concordance between tests was80%, with a Kappa coefficient of 0.48 (IC95%:0.20-0.76). Only two tuberculin (-)/CFP-10+ "anergic" patients were observed. By contrast, six tuberculin +/CFP-10(-) "tuberculin false-positive" patients were observed. These data suggest that the tuberculin test is not an appropriate tool for determining the need for tuberculosis prophylaxis.

Immune Complexome Analysis of Serum and Its Application in Screening for Immune Complex Antigens in Rheumatoid Arthritis

Analysis of circulating immune complexes (CICs) produced during an immune response may be useful in elucidating some aspects of this process. Identification of antigens incorporated into CICs provides information that may be helpful in developing diagnostic and treatment strategies for autoimmune diseases, infection, cancer, and transplantation therapy, and such information might be more relevant than information on free antigens. Because CICs may contain many antigens, comprehensive identification and profiling of such antigens is more effective than immunoblotting detection. We developed a novel proteomic strategy (immune complexome analysis) in which immune complexes (ICs) are separated from serum, digested directly with trypsin, and then subjected to nano-liquid chromatography-tandem mass spectrometry for identifying and profiling antigens in CICs. We applied this strategy to the analysis of CICs in 21 rheumatoid arthritis (RA) patients. Serum samples from 13 healthy donors and 8 osteoarthritis patients were used as controls. CICs containing thrombospondin-1 (TSP-1) and platelet factor 4 (PF4) were found in the serum of 81% and 52% of RA patients, respectively, and in none of the controls. The ICs in the serum of a majority of the RA patients contained TSP-1 or PF4, and these ICs may have potential as alternative biomarkers. Our technique for immune complexome analysis uses routine clinical samples, simple protocols, and widely available equipment. This method may be generally applicable to the study of the relationship between CICs and certain diseases associated with the immune response in animals and humans.

Anti-PAD4 autoantibodies in rheumatoid arthritis: levels in serum over time and impact on PAD4 activity as measured with a small synthetic substrate

Isoform 4 of the human peptidylarginine deiminase (hPAD4) enzyme may be responsible for the citrullination of antigens in rheumatoid arthritis (RA) and has been shown to be itself the target of disease-specific autoantibodies. Here, we have tested whether the level of serum anti-hPAD4 antibodies in RA patients is stable over a period of 10 years and whether the antibodies influence hPAD4-mediated deimination of the small substrate N-α-Benzoyl-l-arginine ethyl ester. RA sera (n = 128) obtained at baseline and after 10 years were assessed for anti-hPAD4 antibodies by a specific immunoassay. For 118 RA patients, serum anti-hPAD4 IgG levels were stable over 10 years. Seven patients who were negative for anti-PAD4 IgG at baseline had become positive after 10 years. Further, total IgG from selected RA patients and controls were purified, and a fraction was depleted for anti-hPAD4 antibodies. Kinetic deimination assays were performed with total IgG and depleted fractions. The k cat and K m values of hPAD4-mediated deimination of N-α-Benzoyl-l-arginine ethyl ester were not affected by the depletion of the anti-hPAD4 antibodies from the total IgG pool. In conclusion, RA patients remain positive for anti-hPAD4 antibodies over time and some patients who are initially anti-hPAD4 negative become positive later in the disease course. The anti-hPAD4 antibodies did not affect the enzymatic activity of hPAD4 when the small substrate N-α-Benzoyl-l-arginine ethyl ester was used. However, this finding may not exclude an effect of these autoantibodies on citrullination of protein substrates in RA.

Gene-environment interaction influences the reactivity of autoantibodies to citrullinated antigens in rheumatoid arthritis

Gene-environment interaction influences the reactivity of autoantibodies to citrullinated antigens in rheumatoid arthritis

Reply to “Gene-environment interaction influences the reactivity of autoantibodies to citrullinated antigens in rheumatoid arthritis”

Reply to “Gene-environment interaction influences the reactivity of autoantibodies to citrullinated antigens in rheumatoid arthritis”

Antibodies to citrullinated proteins in arthritis: pathology and promise

The purpose of this review is to describe how the current knowledge of antibodies to citrullinated protein antigens in rheumatoid arthritis and related conditions emerged; to discuss the diagnostic and prognostic value associated with antibodies to citrullinated protein antigens as a biomarker; and most importantly for this review, to discuss the potential pathogenetic significance of these antibodies. Antibodies to citrullinated protein antigens have evolved from being mainly a diagnostic marker, to being recognized as something that can help us understand fundamental etiologic and pathogenetic features of rheumatoid arthritis. Fundamental in this context is the finding that rheumatoid arthritis can be divided into two distinct subsets by means of presence or absence of antibodies to citrullinated protein antigens. Thus, several genetic as well as environmental risk factors differ between these two variants of rheumatoid arthritis. From analysis of these genetic and environmental risk factors, new testable hypotheses have been produced concerning triggering of antibodies to citrullinated protein antigens, and potential pathogenicity of antibodies to citrullinated protein antigens and accompanying immune reactions. The implications of the findings are that antibodies to citrullinated protein antigens can be used for early and precise diagnosis of a subset of rheumatoid arthritis with worse prognosis than other polyarthritides, and that a new basis is formed for etiologic and pathogenetic studies of antibodies to citrullinated protein antigens-positive rheumatoid arthritis.

Temporal expression pattern of Duffy antigen in rheumatoid arthritis: Up‐regulation in early disease

Temporal expression pattern of Duffy antigen in rheumatoid arthritis: Up‐regulation in early disease

High diagnostic performance of ELISA detection of antibodies to citrullinated antigens in rheumatoid arthritis

Objective: We investigated the rheumatoid arthritis (RA) diagnostic performances of anti‐cyclic citrullinated peptide antibody (anti‐CCP) and antifilaggrin antibody (AFA) in comparison with RF and matrix metalloproteinase‐3 (MMP‐3).Methods: We used a second generation enzyme‐linked immunosorbent assay (ELISA) kit for the detection of anti‐CCP. We constructed recombinant human filaggrin, which was citrullinated in vitro by human peptidylarginine deiminase, and subsequently used it as the coating antigen for AFA‐ELISA. A total of 549 RA patients and 208 other rheumatic disease patients were included in the study.Results: The specificities of anti‐CCP (88.9%) and AFA (94.7%) were superior to those of RF (81.7%) and MMP‐3 (49.5%). The sensitivity of anti‐CCP (87.6%) was superior to all others. However, the sensitivity of AFA (68.7%) was inferior to those of RF (69.8%) and MMP‐3 (75.7%). Furthermore, receiver operating characteristic curves of anti‐CCP and AFA passed closer to the upper left corner than those of RF and MMP‐3, and the areas under the curves (AUC) of AFA and anti‐CCP were significantly larger. In addition, the AUC of anti‐CCP was significantly larger than that of AFA.Conclusion: ELISA detection of antibodies to citrullinated antigens, especially a second generation anti‐CCP, showed higher discriminative ability than other assays, including RF, and would be useful to aid the diagnosis of RA in clinical practice.

What we learn from arthritis models to benefit arthritis patients.

Chronic arthritis is characterized by persistent joint inflammation and concomitant joint destruction. Animal models have been of great value in understanding potential pathogenetic pathways and studying therapeutic principles. The first models were based on T cell-driven pathways and taught us that arthritis can be induced by a variety of stimuli. This suggests that the involvement of a single (auto)antigen in rheumatoid arthritis is unlikely and suggests that the regulation of arthritis can best be approached via bystander suppression. Insight into the pivotal role of TNF alpha and IL-1 has emerged from studies employing a range of common and also novel transgenic models. Combination treatment with both TNF and IL-1 blockers is warranted to control both joint inflammation and joint destruction. Novel approaches with viral gene constructs of cytokines and cytokine inhibitors teach us that efficient gene therapy is a possibility for small joints.

Presence of rheumatoid arthritis (RA) synovial autoantigen recognized by T cells in RA joints

The disease-specific antigen in rheumatoid arthritis (RA) is still unknown. Analyses of the T cell receptor (TCR) repertoire suggested that certain antigen-driven T cells infiltrate into the legion. Efforts to establish T cell lines or clones which recognize RA-specific antigen showed that multiple antigen-reactive T cells were detected in inflamed joints. These antigens fall in two categories, one is foreign antigens which induce molecular mimicry and the other is autoantigens. To date, few etiological studies have shown convincing relationships between RA and infectious diseases. Further, lymphocytes reactive to candidate RA autoantigens were often observed in other autoimmune patients. To determine the primary and RA-specific autoantigen, we focused on T cells specific for RA synovial nurse cells. In the present review, we summarize previous studies on tissue-infiltrating T cells in RA and our recent studies on RA synovial nurse cell-specific autoantigen recognized by T cell clones established from RA joints.

Activation of γδ T cells by mycobacterial antigens in rheumatoid arthritis

IL-17-producing γδ (γδ17) T cells form a versatile subset of cells that respond rapidly to innate stimuli and support the pro-inflammatory functions of different myeloid and lymphoid lineages, being particularly critical in the early stages of inflammatory and autoimmune responses. In mice, under homeostatic conditions, these innate-like lymphocytes are pre-programmed in the fetal thymus, through an intricate process involving both T cell receptor-dependent and -independent signals, which allows them to readily produce IL-17 upon stimulation. However, given their transcriptional and epigenetic wiring, γδ17 T cells are permissive to different environmental instructions, and can readily acquire the ability to co-produce multiple cytokines, such as IFN-γ, IL-22 and GM-CSF, that further propagate inflammation. Moreover, strong IL-23 signals, which are abundantly found in autoinflammatory conditions, are able to induce de novo differentiation of γδ17 T cells from uncommitted precursors, both in mice and humans. This notwithstanding, the exact mechanisms responsible for γδ17 T cell pathogenicity and multifunctionality are still poorly understood, especially in humans. The pathogenic roles attributed to γδ17 T cells in autoimmune diseases stem mainly from their ability to recruit different inflammatory myeloid populations to the target tissue, and to modulate αβ T cell function, either by enhancing inflammatory TH17 responses, or by restraining regulatory Treg cell activity. Given their capacity to link key inflammatory axes of innate and adaptive immunity, a better understanding of the molecular basis underpinning γδ17 T cell plasticity, and how much this feature accounts for their pathophysiological roles, may be critical for developing novel therapeutic approaches. In this review, we discuss the importance of γδ17 T cells in breaking tolerance and enhancing inflammation in various autoimmune diseases, such as multiple sclerosis, psoriasis and rheumatoid arthritis under the light of their basic biological traits, e.g. development, activation, effector functions and plasticity.

Nuclear factor-kappaB: a pivotal transcription factor in chronic inflammatory diseases.

In chronic inflammatory diseases, such as asthma, rheumatoid arthritis, inflammatory bowel disease, and psoriasis, several cytokines recruit activated immune and inflammatory cells to the site of lesions, thereby amplifying and perpetuating the inflammatory state.1 These activated cells produce many other mediators of inflammation. What causes these diseases is still a mystery, but the disease process results from an interplay of genetic and environmental factors. Genes, such as those for atopy in asthma and for HLA antigens in rheumatoid arthritis and inflammatory bowel disease, may determine a patient's susceptibility to the disease and the disease's severity, but environmental factors, often unknown, . . .

Immunologic Mechanisms in Common Rheumatologic Diseases

Rheumatoid arthritis and seronegative spondyloarthropathies are rheumatologic diseases that likely are caused by inflammatory reactions occurring in genetically predisposed individuals mounting an immune response to the antigen. Understanding the immunopathology of these diseases provides insight into their etiology, pathogenesis, and a rationale for therapies targeting immune component interactions. Although the antigen in rheumatoid arthritis is not known, several bacterial antigens have been associated with seronegative spondyloarthropathies. These antigens result in an interaction between the human leukocyte antigen-B27 restricted CD8 positive T lymphocytes and the antigen presenting cell, producing an inflammatory response. Rheumatoid factors are autoantibodies directed against the fragment crystallizable portion of the immunoglobulin G. Rheumatoid factor immunoglobulin G immune complexes contribute to the inflammatory events in the rheumatoid joint, and may play an important role in antigen presentation. A novel antigen capture enzyme linked immunosorbent assay was developed that mimicked B cell surface expressed rheumatoid factor. Conversely, a direct binding enzyme linked immunosorbent assay mimicked secreted rheumatoid factor. Comparison of rheumatoid binding enzyme linked immunosorbent assays showed that the physical state of rheumatoid factor can affect binding characteristics. The state of glycosylation of immunoglobulin G may contribute to its antigenic structure. These physical characteristics may be important in rheumatoid factor's pathogenic role in rheumatoid arthritis.