Immunopathogenesis Of Rheumatoid Arthritis Research Articles

The Role of Autophagy as a Trigger of Post-Translational Modifications of Proteins and Extracellular Vesicles in the Pathogenesis of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease, characterized by persistent joint inflammation, leading to cartilage and bone destruction. Autoantibody production is directed to post-translational modified (PTM) proteins, i.e., citrullinated or carbamylated. Autophagy may be the common feature in several types of stress (smoking, joint injury, and infections) and may be involved in post-translational modifications (PTMs) in proteins and the generation of citrullinated and carbamylated peptides recognized by the immune system in RA patients, with a consequent breakage of tolerance. Interestingly, autophagy actively provides information to neighboring cells via a process called secretory autophagy. Secretory autophagy combines the autophagy machinery with the secretion of cellular content via extracellular vesicles (EVs). A role for exosomes in RA pathogenesis has been recently demonstrated. Exosomes are involved in intercellular communications, and upregulated proteins and RNAs may contribute to the development of inflammatory arthritis and the progression of RA. In RA, most of the exosomes are produced by leukocytes and synoviocytes, which are loaded with PTM proteins, mainly citrullinated proteins, inflammatory molecules, and enzymes that are implicated in RA pathogenesis. Microvesicles derived from cell plasma membrane may also be loaded with PTM proteins, playing a role in the immunopathogenesis of RA. An analysis of changes in EV profiles, including PTM proteins, could be a useful tool for the prevention of inflammation in RA patients and help in the discovery of personalized medicine.

Activated CD90/Thy-1 fibroblasts co-express the Δ133p53β isoform and are associated with highly inflamed rheumatoid arthritis

BackgroundThe p53 isoform Δ133p53β is known to be associated with cancers driven by inflammation. Many of the features associated with the development of inflammation in rheumatoid arthritis (RA) parallel those evident in cancer progression. However, the role of this isoform in RA has not yet been explored. The aim of this study was to determine whether Δ133p53β is driving aggressive disease in RA.MethodsUsing RA patient synovia, we carried out RT-qPCR and RNAScope-ISH to determine both protein and mRNA levels of Δ133p53 and p53. We also used IHC to determine the location and type of cells with elevated levels of Δ133p53β. Plasma cytokines were also measured using a BioPlex cytokine panel and data analysed by the Milliplex Analyst software.ResultsElevated levels of pro-inflammatory plasma cytokines were associated with synovia from RA patients displaying extensive tissue inflammation, increased immune cell infiltration and the highest levels of Δ133TP53 and TP53β mRNA. Located in perivascular regions of synovial sub-lining and surrounding ectopic lymphoid structures (ELS) were a subset of cells with high levels of CD90, a marker of ‘activated fibroblasts’ together with elevated levels of Δ133p53β.ConclusionsInduction of Δ133p53β in CD90+ synovial fibroblasts leads to an increase in cytokine and chemokine expression and the recruitment of proinflammatory cells into the synovial joint, creating a persistently inflamed environment. Our results show that dysregulated expression of Δ133p53β could represent one of the early triggers in the immunopathogenesis of RA and actively perpetuates chronic synovial inflammation. Therefore, Δ133p53β could be used as a biomarker to identify RA patients more likely to develop aggressive disease who might benefit from targeted therapy to cytokines such as IL-6.

Current understanding of the immunological basis of rheumatoid arthritis: from post-translational modification of proteins to the use of disease-modifying antirheumatic drugs

Background. Rheumatoid arthritis (RA) is a multietiological chronic systemic autoimmune disease associated with inflammatory joint damage and extra-articular processes in internal organs. RA is recognized as the most common autoimmune inflammatory arthritis with an incidence of 0.4% to 1.3% of the population. Objective. Summarize current information on the immunopathogenesis of RA based on data from open sources of information. Methods. The selection of publications that covered information about the immunopathogenesis of rheumatoid arthritis was performed using the following keywords: systemic autoimmune diseases, RA, citrullination, carbamylation. Results. RA is considered an immune-mediated disease with a strong genetic influence. An important role in the initiation of the development of RA is played by genetic factors and damage to the mucous membranes in the lungs, oral cavity, and gastrointestinal tract.. In response to the appearance of post-translationally modified (citrullinated/carbamylated) proteins, B-cells induce the production of antibodies to cyclic citrullinated peptide (anti-citrullinated peptide antibodies – ACPA). Rheumatoid factor is another well-studied autoantibody involved in the development of RA. Given the complex role that dendritic cells play in the pathogenesis of RA, targeted therapies are being developed to block their immunogenic or enhance their tolerogenic functions. Dysfunction of fibroblast-like synoviocytes leads to synovial hyperplasia. Disease-modifying antirheumatic drugs (DMARDs) are used to target inflammation and prevent disease progression. Conclusions. Genetic predisposition and specific post-translational modifications of proteins play a significant role in the development of RA. The introduction of DMARDs and the prospects for the use of mesenchymal stem cells and their derivatives allows for the development of new effective treatment strategies to implement more effective control over this disease.

Rheumatoid arthritis and osteoimmunology: The adverse impact of a deregulated immune system on bone metabolism.

The term osteoimmunology describes an interdisciplinary research field that links the investigation of osteology (bone cells) with immunology. The crosstalk between innate and adaptive immune cells and cells involved in bone remodeling, mainly bone-resorbing osteoclasts and bone-forming osteoblasts, becomes particularly obvious in the inflammatory autoimmune disease rheumatoid arthritis (RA). Besides striking inflammation of the joints, RA causes bone loss, leading to joint damage and disabilities as well as generalized osteoporosis. Mechanistically, RA-associated immune cells (macrophages, T cells, B cells etc.) produce high levels of pro-inflammatory cytokines, receptor activator of nuclear factor κB ligand (RANKL) and autoantibodies that promote bone degradation and at the same time counteract new bone formation. Today, antirheumatic therapy effectively ceases joint inflammation and arrests bone erosion. However, the repair of established bone lesions still presents a challenging task and requires improved treatment options. In this review, we outline the knowledge gained over the past years about the immunopathogenesis of RA and the impact of a dysregulated immune system on bone metabolism.

Ultrasound-guided lymph node biopsy sampling to study the immunopathogenesis of rheumatoid arthritis: a well-tolerated valuable research tool

BackgroundAnalyses of lymphoid organs are required to further elucidate the pathogenesis of inflammatory diseases like rheumatoid arthritis (RA). Yet, invasive tissue collection methods are scarcely applied, because they are often considered burdensome, although patients do not always consider invasive methods as a high burden. We aimed to investigate the perspectives of study participants undergoing ultrasound-guided inguinal lymph node (LN) needle biopsy sampling and determine the molecular and cellular quantity and quality of LN biopsies.MethodsTogether with patient research partners, questionnaires were developed to evaluate the motives, expectations, and experiences of participants undergoing a LN biopsy. Healthy controls and RA(-risk) patients were asked to complete these questionnaires before and after the procedure. RNA and lymphocyte yields from obtained LN biopsies were also calculated.ResultsWe included 50 individuals, of which 43 (86%) reported their pre- and post-procedure experiences. The median reported pain on a 5-point Likert scale (1 not to 5 very painful) was 1. Interestingly, almost all (n = 32; 74%) study participants would undergo a second procedure and more than half (n = 23; 54%) would encourage others to take part in the LN biopsy study. Motives for current and future participation were mostly altruistic. Inguinal hematoma occurred frequently, but no other significant or unexpected complications ensued. The LN biopsies yielded sufficient and high-quality RNA and lymphocyte numbers.ConclusionsUltrasound-guided inguinal LN biopsy sampling is well-tolerated, safe, and provides sufficient material for further molecular and cellular analyses. Our participants’ positive experiences endorse the application of this research tool to further elucidate the pathogenesis of RA and other inflammatory diseases.

Recommendations of the Brazilian Society of Rheumatology for the use of JAK inhibitors in the management of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic and autoimmune systemic inflammatory disease that can cause irreversible joint deformities, with increased morbidity and mortality and a significant impact on the quality of life of the affected individual. The main objective of RA treatment is to achieve sustained clinical remission or low disease activity. However, up to 40% of patients do not respond to available treatments, including bDMARDs. New therapeutic targets for RA are emerging, such as Janus kinases (JAKs). These are essential for intracellular signaling (via JAK-STAT) in response to many cytokines involved in RA immunopathogenesis. JAK inhibitors (JAKi) have established themselves as a highly effective treatment, gaining increasing space in the therapeutic arsenal for the treatment of RA. The current recommendations aim to present a review of the main aspects related to the efficacy and safety of JAKis in RA patients, and to update the recommendations and treatment algorithm proposed by the Brazilian Society of Rheumatology in 2017.

The role of NK cells in rheumatoid arthritis.

Natural killer (NK) cells are part of the innate immune system which not only provides a primary response to pathogenic conditions but can also play an important regulatory role in immune responses. Furthermore, these cells can influence immune responses by affecting other involved cells. Human NK cells can be classified as CD56dim and CD56bright; the former demonstrates mostly cytotoxic effects, while the latter comprises mostly tolerant or regulatory NK cells. These cells participate in the immunopathogenesis of rheumatoid arthritis (RA) and their role remains still unclear. We searched PubMed/MEDLINE and Scopus databases to review and analyze relevant literature on the impact of NK cells in the pathogenesis of RA. Although the percentage of NK cells increases in peripheral blood of RA patients compared to healthy individuals, the cytotoxic function of these cells is impaired. It is demonstrated by reduced "perforin+ NK cells" and decreased per-cell lytic function. These cytotoxic NK cells may control the pathogenic bone absorptive function of osteoclasts by directly targeting these cells. Collectively, the evidence collected in the current review emphasizes the possible protective role of CD56dim NK cells in the pathogenesis of RA.

IL-23/IL-17 axis and soluble receptors isoforms sIL-23R and sIL-17RA in patients with rheumatoid arthritis-presenting periodontitis.

BackgroundRheumatoid arthritis (RA) and periodontitis (P) are chronic inflammatory diseases characterized by joint and radiographic bone loss, respectively. IL‐23 and IL‐17 have an essential role in the immunopathogenesis of RA, and P. IL‐23 stimulates Th17 cells through which produces IL‐17, IL‐21, and RANKL. IL‐17 stimulates fibroblasts to produce RANKL, which initiates bone loss in the joints in RA and the periodontal tissue in periodontitis. The aim of this study was to determine the expression pattern of IL‐23/IL‐17 axis and soluble receptors isoforms sIL‐23R and sIL‐17RA of patients with RA presenting P (RAP).Material and methodsHealthy subjects (HS) (n = 42), patients with P (n = 40), RA (n = 20), and patients with RAP (n = 40) were included. Plasma samples were obtained to evaluate the IL‐23, IL‐17A, sIL‐23R, and sIL‐17RA by ELISA technique. A nonparametric Mann‐Whitney U test was used to compare the differences between groups. A Chi‐square was used to compare gender, grade and stage of periodontitis, and DAS28‐ESR between the groups. Spearman's rank correlation coefficient was used to study the association between the molecules and clinical parameters.ResultsIL‐23 levels were increased in the RAP group, and lower sIL‐23R levels were found in the RAP groups. However, IL‐17A was lower in the P and RAP group but not in RA patients. RAP group showed a decrease IL‐17A levels in advanced stages of the periodontal disease.ConclusionThese results suggest that IL‐23 and IL‐17A tend to downregulate their expression patterns when patients present both rheumatoid arthritis and periodontitis.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis.

Microbiota is a balancedecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalisandPrevotellacopri,respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

CCR2/CCL2 and CMKLR1/RvE1 chemokines system levels are associated with insulin resistance in rheumatoid arthritis.

Rheumatoid arthritis (RA) has been associated with insulin resistance (IR). Due to an excess in storage of white adipose tissue, IR has an inflammatory process that overlaps with RA. This is performed by the activation/migration of monocytes carried out by the CCR2/CCL2 and CMKLR1/RvE1 chemokines systems. Furthermore, these can potentiate chronic inflammation which is the central axis in the immunopathogenesis of RA. We evaluated the association between the relative expression of CCR2 and CMKLR1 and the serum levels of their ligands CCL2 and RvE1, in the context of adiposity status with IR as a comorbidity in RA. We studied 138 controls and 138 RA-patients classified with and without IR. We evaluated adiposity, RA activity, IR status and immunometabolic profiles by routine methods. Insulin, CCL2 and RvE1 serum levels were determined by ELISA. Relative expression of CCR2, CMKLR1 and RPS28 as constitutive gene by SYBR green RT-qPCR and 2-ΔΔCT method. Increased measurements were observed of body adiposity and metabolic status as follows: RA with IR>control group with IR>RA without IR> control group without IR. CCR2 and CMKLR1 relative expression was increased in RA without IR versus control without IR. CCR2: 2.3- and 1.3-fold increase and CMKLR1: 3.5- and 2.7-fold increase, respectively. Whereas, CCR2 expression correlates with CMKLR1 expression (rho = 0.331) and IR status (rho = 0.497 to 0.548). CMKLR1 expression correlates with inflammation markers (rho = 0.224 to 0.418). CCL2 levels were increased in the RA groups but levels of RvE1 were increased in RA without IR. We conclude that in RA with IR, the chemokine receptors expression pattern showed a parallel increase with their respective ligands. RA and IR in conjunction with the pathological distribution of body fat mass might exacerbate chronic inflammation. These results suggest that high CCL2 levels and compensatory RvE1 levels might not be enough to resolve the inflammation by themselves.

The immunology of rheumatoid arthritis.

The immunopathogenesis of rheumatoid arthritis (RA) spans decades, beginning with the production of autoantibodies against post-translationally modified proteins (checkpoint 1). After years of asymptomatic autoimmunity and progressive immune system remodeling, tissue tolerance erodes and joint inflammation ensues as tissue-invasive effector T cells emerge and protective joint-resident macrophages fail (checkpoint 2). The transition of synovial stromal cells into autoaggressive effector cells converts synovitis from acute to chronic destructive (checkpoint 3). The loss of T cell tolerance derives from defective DNA repair, causing abnormal cell cycle dynamics, telomere fragility and instability of mitochondrial DNA. Mitochondrial and lysosomal anomalies culminate in the generation of short-lived tissue-invasive effector T cells. This differentiation defect builds on a metabolic platform that shunts glucose away from energy generation toward the cell building and motility programs. The next frontier in RA is the development of curative interventions, for example, reprogramming T cell defects during the period of asymptomatic autoimmunity.

Interactions between Gut Microbiota and Immunomodulatory Cells in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases caused by abnormal immune activation and immune tolerance. Immunomodulatory cells (ICs) play a critical role in the maintenance and homeostasis of normal immune function and in the pathogenesis of RA. The human gastrointestinal tract is inhabited by trillions of commensal microbiota on the mucosal surface that play a fundamental role in the induction, maintenance, and function of the host immune system. Gut microbiota dysbiosis can impact both the local and systemic immune systems and further contribute to various diseases, such as RA. The neighbouring intestinal ICs located in distinct intestinal mucosa may be the most likely intermediary by which the gut microbiota can affect the occurrence and development of RA. However, the reciprocal interaction between the components of the gut microbiota and their microbial metabolites with distinct ICs and how this interaction may impact the development of RA are not well studied. Therefore, a better understanding of the gut microbiota, ICs, and their interactions might improve our knowledge of the mechanisms by which the gut microbiota contribute to RA and facilitate the further development of novel therapeutic approaches. In this review, we have summarized the roles of the gut microbiota in the immunopathogenesis of RA, especially the interactions between the gut microbiota and ICs, and further discussed the strategies for treating RA by targeting/regulating the gut microbiota.

Interleukin 17A gene polymorphism in patients with rheumatoid arthritis

Interleukin 17 plays a key role in the immunopathogenesis of rheumatoid arthritis (RA) and serves as a link between activation of innate and adaptive immune cells, whereas its increased expression may represent one of the causes for uncontrolled inflammation and formation of immunopathological reactions. Among members of the interleukin 17 family, most studied is IL-17A, which is characterized by peak biological activity. IL-17A is one of the important immune mediators able to induce production of other pro-inflammatory cytokines and chemokines and promote recruitment of inflammatory cells, such as monocytes and neutrophils, into inflamed organs. IL17A gene contains a number of polymorphic sites, wherein single-nucleotide substitutions particularly at position the -197G/A may affect its expression level. Here in case-control study we retrospectively examined contribution of genetic polymorphism at the -197G/A position within the IL17A gene. Allele-specific PCR was used to iderntify the -197G/A polymorphism in IL17A gene in groups of patients with rheumatoid arthritis and healthy donors of the Russian ethnic group. Our study was made within a framework on assessing immunogenetic component for rheumatoid arthritis in ethnic Russian subjects in the Chelyabinsk Region. Prevalence of IL17A gene alleles and genotypes obtained in the work is in agreement with the Hardy– Weinberg equilibrium, and is characterized by rather high frequency of allele replacement (40%), which is typical for Caucasoid populations. Thus, it was found that interpopulation differences are characteristic of such gene polymorphism shown not to be associated with predisposition to rheumatoid arthritis in ethnic Russian subjects in the Chelyabinsk Region. Women with RA in our study were found to display certain changfes in frequencies of alleles and genotypes formed due to single-nucleotide substitution in IL17A gene at position -197G/A. However, in women such features cannot be considered as additional risk factors for developing RA. Allele -197*G, homozygous genotype -197G/G may be considered as markers of late-onset for the first RA attack in women. Analysis on distribution of SNP -197G/A alleles and genotypes within the IL17A gene showed that such polymorphism is of low value predictor likely being more associated with some RA clinical variants, but not with predisposition to RA development.

Apoptosis and secondary necrosis of neutrophils and monocytes in the immunopathogenesis of rheumatoid arthritis: a cohort study.

Rheumatoid arthritis (RA) is a progressive chronic inflammatory and autoimmune joint disease. Neutrophils and monocytes are the main target cells of innate immune defense that modulate the course of inflammatory rheumatic diseases. Dysfunctional phagocytosis is a common feature in RA. The aim of this study was to evaluate the diagnostic value of apoptotic changes in neutrophils and monocytes and their relationship with rheumatoid activity measured by the DAS28 score. We used the APOLECT flow cytometric assay for evaluating primary necrotic, apoptotic, and secondary necrotic neutrophils and monocytes determination in RA patients compared with healthy controls. The apoptotic granulocytes were greater in RA patients compared to healthy controls (0.76 ± 0.15% vs. 0.58 ± 0.17%, P < 0.05). The percentage of primary necrotic granulocytes was significantly elevated in RA patients compared to healthy controls (3.84 ± 0.5% vs. 1.96 ± 0.33%). No significant difference was noted for primary necrotic monocytes. The number of secondary necrotic granulocytes and monocytes was high in RA patients (0.94 ± 0.15% vs. 0.4 ± 0.06% and 4.83 ± 1.06% vs. 1.8 ± 0.33%, respectively). The obtained results suggest that neutrophils and monocytes undergo apoptotic modifications which are accompanied by secondary necrotic cells formation in RA. These shifts may lead to autoantigen accumulation that results in the progressive course RA.

An imbalance between blood CD4+CXCR5+Foxp3+ Tfr cells and CD4+CXCR5+Tfh cells may contribute to the immunopathogenesis of rheumatoid arthritis

BackgroundFollicular helper T (Tfh) cells are a subgroup of activated CD4+ T cells which can assist the formation and maintenance of germinal centers. Follicular regulatory T (Tfr) cells are a new class of regulatory T cells which play a major role in suppressing cells in humoral immunity. In contrast to the role of Tfh cells, Tfr cells can inhibit the function of Tfh cells and B cells. Imbalance of blood Tfr/Tfh ratio resulted in the expansion of auto-reactive B cells and auto-antibody production (). However, the effect of Tfr cells and Tfh cells in the pathogenesis of RA (rheumatoid arthritis) is unclear. The purpose of this study was to investigate the function of Tfr cells and Tfh cells in the pathogenesis of RA. MethodsWe recruited 20 patients fulfilled the the American College of Rheumatology diagnosis criteria and 20 healthy controls (HCs). The number of CD4+CXCR5+Foxp3+ Tfr cells and CD4+CXCR5+ Tfh cells in 20 RA patients were measured by flow cytometry analysis. Furthermore, the correlations between the Tfr/Tfh ratio and the characteristic clinical parameters were assessed. The serum levels of IL-21(interleukin-21), CXCL13 (chemokine (C-X-C motif) ligand 13) and TGF-β (Transforming growth factor-β) were measured by ELISA. The formation of ectopic germinal center (GC) of synovial membrane was examined by H&E staining. The transcriptional levels of CXCR5 (C-X-C chemokine receptor type 5), CXCL13, ICOS (inducible co-stimulater) and TGF-β mRNA were also analyzed. In addition, the expression of Bcl-6 (B-cell lymphoma 6), CXCR5, CXCL13 and ICOS in synovial membrane were examined by immunohistochemistry. ResultsRA patients had more Tfh cells in peripheral blood, conversely, the frequency of blood Tfr cells (p < 0.05) and the ratio of Tfr/Tfh were significantly decreased compared to healthy controls (p < 0.05, p < 0.01). Furthermore, the ratio of Tfr/Tfh was negatively correlated with values of ESR (r=-0.57, p < 0.05), RF (r=-0.5275, p < 0.001), CRP (r=-0.4486, p < 0.001), IgG (r=-0.4631, p < 0.05), DAS28 scores (r=-0.5645, p < 0.01), as well as the levels of IL-21(r=-0.7398, p < 0.01), CXCL13 (r=-0.4832, p < 0.05). However, the ratio of Tfr/Tfh was positively with the serum level of TGF-β (r=0.5115, p < 0.05). Higher mRNA expression of CXCR5, CXCL13, ICOS and lower TGF-β mRNA expression were observed in RA patients. The serum expression level of IL-21, CXCL13 was significantly increased and expression of TGF-β was significantly decreased in RA patients. Furthermore, ectopic germinal center formation and higher expression of Bcl-6, CXCR5, ICOS, CXCL13 in the synovial membrane of the joints in RA patients were observed. ConclusionsThe decreased blood CD4+CXCR5+Foxp3+ Tfr cells/CD4+CXCR5+ Tfhcells may be responsible for the immunopathogenesis of RA.

Mesenchymal Stem Cells Improve Rheumatoid Arthritis Progression by Controlling Memory T Cell Response.

In the last years, mesenchymal stem cell (MSC)-based therapies have become an interesting therapeutic opportunity for the treatment of rheumatoid arthritis (RA) due to their capacity to potently modulate the immune response. RA is a chronic autoimmune inflammatory disorder with an incompletely understood etiology. However, it has been well described that peripheral tolerance defects and the subsequent abnormal infiltration and activation of diverse immune cells into the synovial membrane, are critical for RA development and progression. Moreover, the imbalance between the immune response of pro-inflammatory and anti-inflammatory cells, in particular between memory Th17 and memory regulatory T cells (Treg), respectively, is well admitted to be associated to RA immunopathogenesis. In this context, MSCs, which are able to alter the frequency and function of memory lymphocytes including Th17, follicular helper T (Tfh) cells and gamma delta (γδ) T cells while promoting Treg cell generation, have been proposed as a candidate of choice for RA cell therapy. Indeed, given the plasticity of memory CD4+ T cells, it is reasonable to think that MSCs will restore the balance between pro-inflammatory and anti-inflammatory memory T cells populations deregulated in RA leading to prompt their therapeutic function. In the present review, we will discuss the role of memory T cells implicated in RA pathogenesis and the beneficial effects exerted by MSCs on the phenotype and functions of these immune cells abnormally regulated in RA and how this regulation could impact RA progression.

The roles of anti-citrullinated protein antibodies in the immunopathogenesis of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a common systemic autoimmune disease. Its major manifestation is persistent joint inflammation, which can lead to bone destruction and severe disability. The immunopathogenesis of RA is very complex, involving both innate and adaptive immune systems. Recently, the discovery of anti-citrullinated protein antibodies (ACPAs) has revolutionized the diagnosis and our understanding of the immunopathogenesis of RA. The presence of ACPAs is also closely linked to the disease activity of RA. Therefore, it is reasonable to believe that ACPAs and protein citrullination are key issues for the development of RA. We have summarized the recent study results in this review. The first theory concerning the pathogenesis of RA proposed that ACPAs link the well-known genetic and environmental risk factors for developing RA. However, due to the close association between joint inflammation and ACPAs, a more direct role of ACPAs in the immunopathogenesis of RA is anticipated. Within the past 10 years, many studies, including some of our own, have shown that ACPAs can promote an inflammatory response through complement activation, formation of neutrophil extracellular traps, and direct binding to key players, including monocytes, osteoclasts, and osteoblasts, in the mediation of bone destruction in the joints of RA patients. We also present some new perspectives and issues that need to be further investigated.

Imbalance of circulating Tfr/Tfh ratio in patients with rheumatoid arthritis.

Follicular helper T(Tfh) cells and follicular regulatory T(Tfr) cells are critical for the development and maintenance of germinal center and humoral immune responses. Accumulating evidence has demonstrated that the dysregulation of either Tfh or Tfr cells contributes to the pathogenesis of autoimmune diseases. The aim of this study was to examine the numbers of Tfh and Tfr cells in patients with rheumatoid arthritis (RA). Twenty-four patients with RA patients and 20 health controls (HCs) were enrolled in this study. We analyzed the numbers of Tfh (CD4+ CXCR5+ PD-1hi) cells and Tfr (CD4+ CXCR5+CD127lo) cells in 24 RA patients via flow cytometry. The level of the soluble PD-1 and its ligands (sPD-L1 and sPDL-2) were examined by ELISA. Flow cytometry revealed that both circulating Tfh and Tfr cells were increased in RA patients compared with HCs. More importantly, the ratio of Tfr/Tfh was decreased, indicating a disruption of the balance between Tfh and Tfr. The Tfr/Tfh ratio was inversely correlated with level of serum CRP, ESR, RF, anti-CCP, IgG and DAS28 index. We also found that the serum level of sPD-1 was significantly elevated in the RA patients, which was positively correlated with CRP, ESR and the number of Tfh cells. These results indicate that an imbalance of circulating Tfr and Tfh cells may be involved in the immunopathogenesis of RA and may provide novel insight for the development of RA therapies.

The role of aberrant expression of T cell miRNAs affected by TNF-\u03b1 in the immunopathogenesis of rheumatoid arthritis

BackgroundTumor necrosis factor-alpha (TNF-α) can cause diverse T cell dysfunctions in patients with rheumatoid arthritis (RA). It is involved in the regulation of microRNAs (miRNAs) expression in different cell types. We hypothesized that the expression of T cell miRNAs would be affected by TNF-α, and these miRNAs could participate in the immunopathogenesis of RA.MethodsExpression profiles of 270 human miRNAs in Jurkat cells, cultured in the presence or absence of TNF-α for 7 days were analyzed by real-time polymerase chain reaction. Potentially aberrantly expressed miRNAs were validated using T cell samples from 35 patients with RA and 15 controls. Transfection studies were conducted to search for gene expression and biological functions regulated by specific miRNAs.ResultsInitial analysis revealed 12 miRNAs were significantly lower, whereas the expression level of miR-146a was significantly higher in Jurkat cells after being cultured with TNF-α for 7 days. Decreased expression of miR-139-3p, miR-204, miR-760, miR-524-5p, miR-136, miR-548d-3p, miR-214, miR-383, and miR-887 were noted in RA T cells. Expression levels of miR-139-3p, miR-204, miR-214, and miR-760 were correlated with the use of biologic agents. The transfection of miR-214 mimic suppressed TNF-α-mediated apoptosis of Jurkat cells. Increased phosphorylation of extracellular regulating kinase (ERK) and c-Jun N-terminal kinase (JNK) was noted in RA T cells and Jurkat cells after TNF-α exposure. Transfection of Jurkat cells with miR-214 mimic suppressed both the basal and TNF-α-mediated ERK and JNK phosphoryation.ConclusionsAmong T cell miRNAs affected by TNF-α, the expression levels of nine miRNAs were decreased in T cells from patients with RA. The expression levels of miR-139-3p, miR-204, miR-214, and miR-760 increased in RA patients receiving biologic agents. The transfection of miR-214 reversed the TNF-α-mediated cells apoptosis and inhibited the phosphorylation of ERK and JNK in Jurkat cells.

Characterization of IgG glycosylation in rheumatoid arthritis patients by MALDI-TOF-MSn and capillary electrophoresis.

An analytical method based on the combination of multistage mass spectrometry (MSn) and capillary electrophoresis (CE) was developed for the analysis of immunoglobulin G (IgG) glycosylation in rheumatoid arthritis (RA) patients. It has been recently suggested that IgG glycosylation defect may be involved in RA immunopathogenesis. Complete characterization of glycans, including both qualitative and quantitative analysis, requires a combination of different techniques, and accurate, robust, sensitive, and high-throughput methodologies are important for analysis of clinical samples. In the present study, N-glycosylation of IgG in RA patients and in healthy people was characterized through identification of the released glycans using multistage matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MSn), and quantitation by CE. Assignment of the IgG N-glycan structures was made through branching pattern analysis by MSn with high-throughput. Further accurate quantitation indicated that galactosylation and sialylation of IgG N-glycans in RA cases were significantly lower than in healthy subjects. The results indicate that CE coupled with MSn can identify abnormal glycosylation of IgG in RA patients compared with healthy people, and that the present work is useful for RA mechanism studies and RA diagnosis. Graphical Abstract Qualitative and quantitative analysis of IgG glycosylation in rheumatoid arthritis patients by MALDI-TOF-MSn and capillary electrophoresis.