The role of citrullinated protein antibodies in predicting erosive disease in rheumatoid arthritis: a systematic literature review and meta-analysis

Anti-mutated citrullinated vimentin antibodies in antiphospholipid syndrome: diagnostic value and relationship with clinical features

Antiphospholipid antibodies (aPLs) are a heterogeneous group of autoantibodies essential for the diagnosis of antiphospholipid syndrome (APS) but do not predict clinical manifestations or disease progression. Hence, the co-presence of other antibodies may prove useful. Autoimmunity directed toward vimentin and other citrullinated peptides was established in rheumatoid arthritis (RA) and in other autoimmune conditions including systemic lupus erythematosus (SLE). We have previously described the presence of autoantibodies directed against vimentin/cardiolipin complex in patients with antiphospholipid syndrome (APS), but there are no data on the role of citrullinated vimentin in APS. Thus, we evaluated the prevalence and clinical significance of anti-MCV in APS patients. The study group consisted of 79 unselected outpatients with APS. Control groups included 25 patients with SLE, 30 patients with RA, and 20 healthy subjects age- and sex-matched. To detect anti-MCV, anti-vimentin, anti-vimentin/cardiolipin, and anti-CCP2 antibodies, commercial or homemade enzyme-linked immunosorbent assays (ELISA) were performed. Anti-MCV antibodies were found in a high percentage of APS patients (26.6%). A significant correlation between anti-MCV and anti-vimentin/cardiolipin serum levels was observed (p = 0.029). Moreover, vimentin reactivity was increased by its citrullination or conjugation with cardiolipin (p = 0.01 and p < 0.001, respectively). Interestingly, anti-MCV was found associated with the presence of arthritis (p = 0.011) and anti-vimentin/cardiolipin was highly specific for the presence of arterial or venous thrombosis in APS (p = 0.003 and p = 0.002, respectively). The detection of additional autoantibodies may contribute to clinical assessment of APS patients. Citrullination may occur in APS and play a role in the pathogenesis of this condition.

KEY POINTS

•Anti-MCV antibodies can be found in APS patients and are associated with the presence of arthritis. •Anti-vimentin/cardiolipin is strongly associated with the presence of thrombosis (both arterial and venous). •Citrullination occurs in APS, participate in disease pathogenesis, and influence clinical picture.

Vitamin D and rheumatoid arthritis: an ongoing mystery

PURPOSE OF REVIEW

In recent years, there has been a growing interest in the value of vitamin D and its effects on autoimmunity. The aim of this review is to summarize the current knowledge on the association between vitamin D and rheumatoid arthritis (RA) in terms of prevalence, disease activity, clinical expression, serology and gene polymorphisms of vitamin D receptors.

RECENT FINDINGS

Studies have shown contrasting findings concerning the association between vitamin D levels and RA. Vitamin D seems to have immunomodulatory properties. Therefore, low vitamin D levels could contribute to increased immune activation. However, the potential role of vitamin D supplementation in preventing RA manifestation and its beneficial role as a component of RA treatment remain controversial. The relationship between RA susceptibility and vitamin D polymorphisms is also unclear.

SUMMARY

Despite advancements synthesized by some recent meta-analyses, the relationship between vitamin D and RA requires further evaluation. Further research is needed to confirm the relationship between RA susceptibility and vitamin D polymorphisms and to determine whether vitamin D plays a role in preventing the manifestation of RA. Finally, additional studies are required to determine the impact and optimal amount of vitamin D supplementation in the treatment of RA patients.

Cost-Effectiveness Analysis of Abatacept Compared with Adalimumab on Background Methotrexate in Biologic-Naive Adult Patients with Rheumatoid Arthritis and Poor Prognosis

OBJECTIVES

To assess cost effectiveness of abatacept versus adalimumab, each administered with methotrexate, in treating patients with rheumatoid arthritis (RA) stratified according to baseline anticitrullinated protein antibody (ACPA) levels (marker of poor prognosis in RA).

METHODS

A payer-perspective cost-effectiveness model simulated disease progression in patients with RA who had previously failed conventional disease-modifying antirheumatic drugs and were starting biologic therapy. Patients commenced treatment with abatacept or adalimumab plus methotrexate and were evaluated after 6 months. Therapy continuation was based on the European League Against Rheumatism treatment response; disease progression was based on the Health Assessment Questionnaire Disability Index score. These score changes were used to estimate health state utilities and direct medical costs. Quality-adjusted life-years (QALYs) and incremental cost per QALY gained were calculated by baseline ACPA groups (Q1, 28-234 AU/ml; Q2, 235-609 AU/ml; Q3, 613-1045 AU/ml; and Q4, 1060-4894 AU/ml). Scenario analysis and one-way and probabilistic sensitivity analyses were used to evaluate robustness of model assumptions.

RESULTS

Abatacept resulted in QALY gain versus adalimumab in ACPA Q1, Q3, and Q4; between-treatment difference (difference: Q1, -0.115 Q2, -0.009 Q3, 0.045; and Q4, 0.279). Total lifetime discounted cost was higher for abatacept versus adalimumab in most quartiles (Q2, £77,612 vs. £77,546; Q3, £74,441 vs. £73,263; and Q4, £78,428 vs. £76,696) because of longer time on treatment. Incremental cost per QALY for abatacept (vs. adalimumab) was the lowest in the high ACPA titer group (Q4, £6200/QALY), followed by the next lowest titer group (Q3, £26,272/QALY).

CONCLUSIONS

Abatacept is a cost effective alternative to adalimumab in patients with RA with high ACPA levels.

Relationship between cartilage oligomeric matrix protein (COMP) and rheumatoid arthritis severity

Background

Serum cartilage oligomeric matrix protein (COMP) is a non-collagen glycoprotein produced by the cartilage, synovium, tendon, and meniscus. Recent studies showed that COMP is a reliable factor for monitoring cartilage damage.

Objective

To determine the relationship between serum COMP concentration and the severity of rheumatoid arthritis (RA).

Methods

This cross-sectional study lasted from 2013 to 2015 at the Rheumatology Clinic of Ghaem Hospital, Mashhad, Iran. The study population consisted of eligible patients who presented to our clinic during the study period. Four groups (150 subjects) were included as early RA (50 patients), late RA (50 patients), grades II and III OA (osteoarthritis) (25 cases, 17 grade II and 8 grade III joint destruction), and healthy controls (25 individuals). These were included consecutively. Serum COMP level was assessed by sandwich ELISA technique. In addition, ESR, hs-CRP, serum RF, and anti-CCP were assayed. X-rays of the knees (in OA) and hands (in RA) were examined for the degree of joint damage/erosion using the Short Erosion Scale (SES) in RA and Kellgren-Lawrence grading in OA. Analysis of variance (ANOVA) to compare mean COMP level among the groups and ROC (Receiver Operating Characteristic) analysis to determine the diagnostic accuracy of COMP in diagnosis of late RA were used by SPSS software (ver. 20.0).

Results

Mean (±SD) serum COMP levels were 18 (±10.6) U/L in early RA, 19.3 (±9.6) U/L in late RA, 10.9 (±4.5) U/L in OA, and 4.2 (±3.8) in controls; p<0.001. Serum COMP level was higher in RA and OA groups when compared to control group. Mean (±SD) SES score was 13.5 (±7.5) in early RA and 16.4 (±9.7) in late RA (p=0.093). There was a significant positive correlation between COMP level and disease severity in early RA (r=0.677, p<0.001) as well as in late RA (r=0.753, p<0.001). Serum COMP level at a concentration of 15.25 U/L had a sensitivity of 68% and specificity of 70% to discriminate late RA from early RA (area under curve= 69% (95% CI: 58% to 79%; p=0.001).

Conclusion

COMP had positive significant correlation with early and late RA severity. This serum biomarker can be a useful and easy tool for monitoring of RA patients either at early or late stages of the disease.

The Infectious Basis of ACPA-Positive Rheumatoid Arthritis

Rheumatoid arthritis (RA) is associated with HLA-DRB1 shared epitope (HLA-DRB1SE) and anti-citrullinated protein autoantibodies (ACPAs). ACPAs precedes the onset of clinical and subclinical RA. There are strong data for three infectious agents as autoimmunity triggers in RA, namely Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans causes of periodontal disease (PD), and Epstein-Barr virus (EBV). P. gingivalis expresses arginine gingipains, that cleave proteins at the arginine residues, and peptidyl arginine deiminase (PPAD), which citrullinates arginine residues of proteins, thus forming neoantigens that lead to ACPA production. Peripheral blood plasmablasts from ACPA+RA patients produce ACPAs the majority of which react against P. gingivalis. A. actinocycetemcomitans produces leukotoxin A, a toxin that forms pores in the neutrophil membranes and leads to citrullination and release of citrullinated autoantigens in the gums. EBV can infect B cells and epithelial cells and resides as latent infection in resting B cells. Abs against citrullinated peptides derived from EBV nuclear antigen appear years before RA and cross-react with human citrullinated fibrin. Citrullinated proteins are potential arthritogenic autoantigens in RA. The conversion of arginine to citrulline increases the peptide binding affinity to HLA-DRB1SE. Also, citrullinated fibrinogen induces arthritis in HLA-DRB1^*0401 transgenic mice, and transfer of their splenic T cells causes arthritis to recipient mice.

A critical role for plasma kallikrein in the pathogenesis of autoantibody-induced arthritis

The plasma kallikrein-kinin system (KKS) consists of serine proteases, prekallikrein (pKal) and factor XII (FXII), and a cofactor, high-MW kininogen (HK). Upon activation, activated pKal and FXII cleave HK to release bradykinin. Activation of this system has been noted in patients with rheumatoid arthritis, and its pathogenic role has been characterized in animal arthritic models. In this study, we generated 2 knockout mouse strains that lacked pKal and HK and determined the role of KKS in autoantibody-induced arthritis. In a K/BxN serum transfer-induced arthritis (STIA) model, mice that lacked HK, pKal, or bradykinin receptors displayed protective phenotypes in joint swelling, histologic changes in inflammation, and cytokine production; however, FXII-deficient mice developed normal arthritis. Inhibition of Kal ameliorated arthritis severity and incidence at early stage STIA and reduced the levels of major cytokines in joints. In addition to releasing bradykinin from HK, Kal directly activated monocytes to produce proinflammatory cytokines, up-regulated their C5aR and FcRIII expression, and released C5a. Immune complex increased pKal activity, which led to HK cleavage. The absence of HK is associated with a decrease in joint vasopermeability. Thus, we identify a critical role for Kal in autoantibody-induced arthritis with pleiotropic effects, which suggests that it is a new target for the inhibition of arthritis.-Yang, A., Zhou, J., Wang, B., Dai, J., Colman, R. W., Song, W., Wu, Y. A critical role for plasma kallikrein in the pathogenesis of autoantibody-induced arthritis.

Role of tenascin-C in articular cartilage

Tenascin-C (TN-C) is a glycoprotein component of the extracellular matrix (ECM). TN-C consists of four distinct domains, including the tenascin assembly domain, epidermal growth factor-like repeats, fibronectin type III-like repeats, and the fibrinogen-like globe (FBG) domain. This review summarizes the role of TN-C in articular cartilage. Expression of TN-C is associated with the development of articular cartilage but markedly decreases during maturation of chondrocytes and disappears almost completely in adult articular cartilage. Increased expression of TN-C has been found at diseased cartilage and synovial sites in osteoarthritis (OA) and rheumatoid arthritis (RA). TN-C is increased in the synovial fluid in patients with OA and RA. In addition, serum TN-C is elevated in RA patients. TN-C could be a useful biochemical marker for joint disease. The addition of TN-C results in different effects among TN-C domains. TN-C fragments might be endogenous inducers of cartilage matrix degradation; however, full-length TN-C could promote cartilage repair and prevent cartilage degeneration. The deficiency of TN-C enhanced cartilage degeneration in the spontaneous OA in aged joints and surgical OA model. The clinical significance of TN-C effects on cartilage is not straightforward.

Personalized medicine in rheumatology: the paradigm of serum autoantibodies

The sequencing of the human genome is now well recognized as the starting point of personalized medicine. Nonetheless, everyone is unique and can develop different phenotypes of the same disease, despite identical genotypes, as well illustrated by discordant monozygotic twins. To recognize these differences, one of the easiest and most familiar examples of biomarkers capable of identifying and predicting the outcome of patients is represented by serum autoantibodies. In this review, we will describe the concept of personalized medicine and discuss the predictive, prognostic and preventive role of antinuclear antibodies (ANA), anti-citrullinated peptide antibodies (ACPA), rare autoantibodies and anti-drug antibodies (ADA), to evaluate how these can help to identify different disease immune phenotypes and to choose the best option for treating and monitoring rheumatic patients in everyday practice. The importance of ANA resides in the prediction of clinical manifestations in systemic sclerosis and systemic lupus erythematosus and their association with malignancies. ACPA have a predictive role in rheumatoid arthritis, they are associated with the development of a more aggressive disease, extra-articular manifestations and premature mortality in RA patients; moreover, they are capable of predicting therapeutic response. Rare autoantibodies are associated with different disease manifestations and also with a greater incidence of cancer. The determination of ADA levels may be useful in patients where the clinical efficacy of TNF-α inhibitor has dropped, for the assessment of a right management. The resulting scenario supports serum autoantibodies as the cornerstone of personalized medicine in autoimmune diseases.

Circulating DNA in rheumatoid arthritis: pathological changes and association with clinically used serological markers

Background

Early diagnosis of rheumatoid arthritis (RA) is crucial to providing effective therapy and often hampered by unspecific clinical manifestations. Elevated levels of extracellular circulating DNA (cirDNA) in patients with autoimmune disease were found to be associated with etiopathogenesis. To our knowledge, this is the first study to investigate the putative diagnostic use of cirDNA in RA and its association with disease activity.

Methods

Blood samples were taken from 63 healthy subjects (HS) and 74 patients with RA. cirDNA was extracted from plasma and cell surface-bound cirDNA fractions (csbDNA). cirDNA concentration was measured by quantitative real-time polymerase chain reaction. Rheumatoid factor was analyzed by immunonephelometry, whereas C-reactive protein and anticitrullinated protein/peptide antibodies (ACPA) were detected by enzyme-linked immunosorbent assay.

Results

Plasma cirDNA was significantly elevated in patients with RA compared with HS (12.0 versus 8.4 ng/ml, p < 0.01). In contrast, nuclear csbDNA (n-csbDNA) was significantly decreased (24.0 versus 50.8 ng/ml, p < 0.01), whereas mitochondrial csbDNA (m-csbDNA) was elevated (1.44 × 10⁶ copies/ml versus 0.58 × 10⁶ copies/ml, p < 0.05) in RA. The combination of csbDNA (mitochondrial + nuclear) with ACPA reveals the best positive/negative likelihood ratios (LRs) for the discrimination RA from HS (LR+ 61.00, LR− 0.03) in contrast to ACPA (LR+ 9.00, LR− 0.19) or csbDNA (LR+ 8.00, LR− 0.18) alone.

Conclusions

Nuclear and mitochondrial cirDNA levels in plasma and on the surface of blood cells are modulated in RA. Combination of cirDNA values with ACPA can improve the serological diagnosis of RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1295-z) contains supplementary material, which is available to authorized users.

Collagen Autoantibodies and Their Relationship to CCP Antibodies and Rheumatoid Factor in the Progression of Early Rheumatoid Arthritis

Serum autoantibodies to cyclic citrullinated peptides (anti-CCP) and rheumatoid factor (RF) are important markers for diagnosis and prognosis of rheumatoid arthritis (RA), but their autoantigens are not cartilage-specific. Autoantibodies to joint-specific type II collagen (CII) also occur in RA, and monoclonal antibodies of similar specificity induce collagen antibody-induced arthritis in animals, but their role in RA is uncertain. We utilized an enzyme-linked immunosorbent assay (ELISA) with the CB10 peptide of CII to compare the frequency of autoantibodies with those of anti-CCP and RF in stored sera from a prospective study of 82 patients with early RA to examine the outcome, defined as remission (n = 23), persisting non-erosive arthritis (n = 27), or erosions (n = 32). Initial frequencies of anti-CB10, anti-CCP and RF were 76%, 54%, and 57% in RA, and 4%, 0%, and 9% in 136 controls. The frequency of anti-CB10 was unrelated to outcome, but anti-CCP and RF increased with increasing severity, and the number of autoantibodies mirrored the severity. We suggest RA is an immune complex-mediated arthritis in which the three antibodies interact, with anti-CII inducing localized cartilage damage and inflammation resulting in citrullination of joint proteins, neoepitope formation, and a strong anti-CCP response in genetically-susceptible subjects, all amplified and modified by RF.

Bone as a Target Organ in Rheumatic Disease: Impact on Osteoclasts and Osteoblasts

Dysregulated bone remodeling occurs when there is an imbalance between bone resorption and bone formation. In rheumatic diseases, including rheumatoid arthritis (RA) and seronegative spondyloarthritis, systemic and local factors disrupt the process of physiologic bone remodeling. Depending upon the local microenvironment, cell types, and local mechanical forces, inflammation results in very different effects on bone, promoting bone loss in the joints and in periarticular and systemic bone in RA and driving bone formation at enthesial and periosteal sites in diseases such as ankylosing spondylitis (AS), included within the classification of axial spondyloarthritis. There has been a great deal of interest in the role of osteoclasts in these processes and much has been learned over the past decade about osteoclast differentiation and function. It is now appreciated that osteoblast-mediated bone formation is also inhibited in the RA joint, limiting the repair of erosions. In contrast, osteoblasts function to produce new bone in AS. The Wnt and BMP signaling pathways have emerged as critical in the regulation of osteoblast function and the outcome for bone in rheumatic diseases, and these pathways have been implicated in both bone loss in RA and bone formation in AS. These pathways provide potential novel approaches for therapeutic intervention in diseases in which inflammation impacts bone.

Inflammation and epigenetic regulation in osteoarthritis

Osteoarthritis (OA) was once defined as a non-inflammatory arthropathy, but it is now well-recognized that there is a major inflammatory component to this disease. In addition to synovial cells, articular chondrocytes and other cells of diarthrodial joints are also known to express inflammatory mediators. It has been proposed that targeting inflammation pathways could be a promising strategy to treat OA. There have been many reports of cross-talk between inflammation and epigenetic factors in cartilage. Specifically, inflammatory mediators have been shown to regulate levels of enzymes that catalyze changes in DNA methylation and histone structure, as well as alter levels of non-coding RNAs. In addition, expression levels of a number of these epigenetic factors have been shown to be altered in OA, thereby suggesting potential interplay between inflammation and epigenetics in this disease. This review provides information on inflammatory pathways in arthritis and summarizes published research on how epigenetic regulators are affected by inflammation in chondrocytes. Furthermore, we discuss data showing how altered expression of some of these epigenetic factors can induce either catabolic or anti-catabolic effects in response to inflammatory signals. A better understanding of how inflammation affects epigenetic factors in OA may provide us with novel therapeutic strategies to treat this condition.

The role of anticitrullinated protein antibodies in the early stages of rheumatoid arthritis

PURPOSE OF REVIEW

This review provides an update on the recent discoveries on the role of anticitrullinated protein antibodies (ACPA) in early rheumatoid arthritis (RA).

RECENT FINDINGS

RA is characterized by an immune response against posttranslationally modified proteins, in particular citrullinated proteins. Recent studies have found that the ACPA response matures shortly before clinical disease manifests itself and is characterized by an increase in titre, isotype switching, antigen-recognition profile, and a change in the Fc-glycosylation pattern. To date, many citrullinated autoantigens have been identified and novel studies suggest that the human leucocyte antigen class II locus may directly influence the maturation of the ACPA response via antigen-specific T cells. Clinical studies have demonstrated that effective treatment of arthritis can lead to reduced ACPA levels or a change in composition of ACPA. In addition to ACPA, autoantibodies targeting other posttranslational modifications have been identified and may be associated with disease prognosis.

SUMMARY

Key studies have demonstrated that autoimmunity against citrullinated proteins is already present in preclinical RA and matures over time. Future studies are required to reveal whether autoantibodies and the B cells that produce them play a role in disease development or can function as biomarkers for disease maturation.

Anti-Citrullinated Cyclic Peptide Antibody and Functional Disability Are Associated With Poor Sleep Quality in Rheumatoid Arthritis

Objectives

This study aims to determine the predictors of poor sleep quality in rheumatoid arthritis (RA).

Patients and methods

This was a monocentric, cross sectional, case-control study which was conducted at the Putrajaya Hospital, Malaysia. We recruited 46 patients with RA (3 males; 43 females; mean age 48.15±14.96) and 46 age and sex-matched healthy controls (3 males; 43 females; mean age 47.11±12.22). RA patients were assessed for their disease activity based on disease activity score in 28 joints, disease damage based on radiographic erosions, and functional status based on Health Assessment Questionnaire Disability Index. The Pittsburgh Sleep Quality Index (PSQI) scores were determined by interviewing all the subjects. Subjects with RA were further subdivided based on their PSQI scores as "good sleepers" with PSQI scores of <5 and "poor sleepers" with PSQI scores of ≥5.

Results

The percentage of poor sleepers was significantly higher among RA patients (47.83% versus 9.57%). Median scores of 5 out of 7 components of the PSQI were higher among RA patients compared to controls. Among poor sleepers with RA, a significantly higher proportion tested positive for anti-citrullinated cyclic peptide autoantibodies (p=0.037). Besides, poor sleepers had significantly higher median Health Assessment Questionnaire Disability Index (p=0.017) than good sleepers. However, both Health Assessment Questionnaire Disability Index (p=0.968) and anti-citrullinated cyclic peptide (p=0.431) were insignificant when entered in the equation of a logistic regression model.

Conclusion

The findings of this study demonstrate a link between functional disability, anti-citrullinated cyclic peptide antibodies, and sleep quality in RA.

Pharmacological Value of Murine Delayed-type Hypersensitivity Arthritis: A Robust Mouse Model of Rheumatoid Arthritis in C57BL/6 Mice

In this MiniReview, we summarize the body of knowledge on the delayed-type hypersensitivity arthritis (DTHA) model, a recently developed arthritis model with 100% incidence, low variation and synchronized onset in C57BL/6 (B6) mice, and compare it to other murine arthritis models. It is desirable to have robust arthritis models in B6 mice, as many transgene strains are bred on this background. However, several of the most widely used mouse model of arthritis cannot be induced in B6 mice without the drawback of lower incidence, reduced severity and higher variation, if at all. DTHA is induced by modifying a classical methylated bovine serum albumin (mBSA)-induced DTH response by administering a cocktail of anti-type II collagen antibodies (anti-CII) between immunization and challenge. Arthritis affects one, predefined paw in which acute inflammation and severe arthritis rapidly develop and peak after 4-7 days. Disease is self-resolving over the course of around 3 weeks. Disease manifestations resemble those seen in other arthritis models and include bone erosion, cartilage destruction, oedema, pannus and new bone formation. Induction of DTHA is dependent on CD4⁺ T cells while B cells are dispensable. The DTHA model is set apart from other murine arthritis models in that it can be induced in B6 mice with 100% incidence and with high and consistent severity. This is the clearest advantage of the model, as the mechanisms of disease and clinical manifestations can be found in other arthritis models. The model holds potential for future modifications that may improve the lack of chronicity.

Effects of TNF Inhibitors on Parathyroid Hormone and Wnt Signaling Antagonists in Rheumatoid Arthritis

Tumor necrosis factor α inhibitors (TNFi) are the major class of biologic drug used for the treatment of Rheumatoid arthritis (RA). Their effects on inflammation and disease control are well established, but this is not true also for bone metabolism, especially for key factors as parathyroid hormone and Wnt pathway. Those two pathways are gaining importance in the pathogenesis RA bone damage, both systemic and local, but how the new treatment affects them is still largely unknown. We studied 54 RA patients who were starting an anti-TNFα treatment due to the failure of the conventional synthetic disease-modifying antirheumatic drugs. Serum levels of Wnt/βcatenin pathway inhibitors (Dickkopf-related protein 1, Dkk1, and Sclerostin), Parathyroid hormone (PTH), vitamin D, and bone turnover markers were measured at baseline in the morning after fasting and after 6 months of therapy. We found a significant percentage increase in serum PTH (+32 ± 55 %; p = 0.002) and a decrease in Dkk1 mean serum levels (-2.9 ± 12.1; p = 0.05). PTH percentage changes were positively correlated both with C-terminal telopeptide of type I collagen and Dkk1 percentage changes. Sclerostin serum levels showed no significant difference. TNFi treatment provokes in the short term a rise in PTH levels and a decrease in Dkk1 serum levels. The increase of PTH might promote bone resorption and blunt the normalization of Dkk1 serum levels in RA. Those data give a new insight into TNFi metabolic effects on bone and suggest new strategies to achieve better results in terms of prevention of bone erosions and osteoporosis with TNFi treatment in RA.

Factors predicting pain and early discontinuation of tumour necrosis factor-α-inhibitors in people with rheumatoid arthritis: results from the British society for rheumatology biologics register

Background

We examined pain levels in 2 cohorts assembled from the British Society for Rheumatology Biologics Register (BSRBR), and investigated which factors predicted Bodily Pain scores and discontinuation of TNFα-inhibitors.

Method

Data were retrieved from BSRBR-RA databases for up to 1 year after commencing TNFα-inhibitors (n = 11995) or being treated with non-biologic therapies (n = 3632). Bodily Pain scores were derived from the Short Form-36 (SF36) questionnaire and norm-transformed to allow comparison with UK population averages. Discontinuation data were from physician reports. Other data, including 28-joint disease activity score (DAS28) measurements, were from clinical examination, interview, medical records and self-report questionnaires. DAS28-P was derived as the proportion of DAS28 attributed to patient-reported factors (tender joint count and visual analogue score). Missing baseline variables from both cohorts were imputed into 20 replicate datasets. Odds ratios (OR) and adjusted OR were calculated for higher than median pain within each cohort.

Results

Participants reported moderate to severe pain at baseline, and pain scores remained >1SD worse than normal population standards at 1 year, even when disease activity responded to treatment. Baseline pain was associated with DAS28-P, worse physical function, worse mental health, and DAS28. After logistic regression, independent predictors of higher than median pain at follow up were baseline Bodily Pain score, higher DAS28-P, worse physical function or mental health and co-morbidities. Higher age, male gender, and higher BMI were additional independent predictors of higher pain in participants who received TNFα-inhibitors. Baseline pain was also one of the predictors of discontinuation of the first TNFα-inhibitor within 1 year, as were female gender, current smoking, co-morbidities, extra-articular manifestations and worse function.

Conclusion

Pain persists in people with treated RA, even in those for whom inflammation responds to treatment. Worse pain outcomes are predicted by factors different to those typically found to predict inflammatory disease activity in other studies. Worse pain at baseline also predicts discontinuation of TNFα-inhibitors. Improved pain management should complement inflammatory disease suppression in RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1192-7) contains supplementary material, which is available to authorized users.

Posttranslational Modifications and the Immunogenicity of Biotherapeutics

Whilst the amino acid sequence of a protein is determined by its gene sequence, the final structure and function are determined by posttranslational modifications (PTMs), including quality control (QC) in the endoplasmic reticulum (ER) and during passage through the Golgi apparatus. These processes are species and cell specific and challenge the biopharmaceutical industry when developing a production platform for the generation of recombinant biologic therapeutics. Proteins and glycoproteins are also subject to chemical modifications (CMs) both in vivo and in vitro. The individual is naturally tolerant to molecular forms of self-molecules but nonself variants can provoke an immune response with the generation of anti-drug antibodies (ADA); aggregated forms can exhibit enhanced immunogenicity and QC procedures are developed to avoid or remove them. Monoclonal antibody therapeutics (mAbs) are a special case because their purpose is to bind the target, with the formation of immune complexes (ICs), a particular form of aggregate. Such ICs may be removed by phagocytic cells that have antigen presenting capacity. These considerations may frustrate the possibility of ameliorating the immunogenicity of mAbs by rigorous exclusion of aggregates from drug product. Alternate strategies for inducing immunosuppression or tolerance are discussed.

Depletion of regulatory T cells leads to an exacerbation of delayed-type hypersensitivity arthritis in C57BL/6 mice that can be counteracted by IL-17 blockade

Rodent models of arthritis have been extensively used in the elucidation of rheumatoid arthritis (RA) pathogenesis and are instrumental in the development of therapeutic strategies. Here we utilise delayed-type hypersensitivity arthritis (DTHA), a model in C57BL/6 mice affecting one paw with synchronised onset, 100% penetrance and low variation. We investigate the role of regulatory T cells (Tregs) in DTHA through selective depletion of Tregsand the role of IL-17 in connection with Tregdepletion. Given the relevance of Tregsin RA, and the possibility of developing Treg-directed therapies, this approach could be relevant for advancing the understanding of Tregsin inflammatory arthritis. Selective depletion of Tregswas achieved using aFoxp3-DTR-eGFPmouse, which expresses the diphtheria toxin receptor (DTR) and enhanced green fluorescent protein (eGFP) under control of theFoxp3gene. Anti-IL-17 monoclonal antibody (mAb) was used for IL-17 blockade. Numbers and activation of Tregsincreased in the paw and its draining lymph node in DTHA, and depletion of Tregsresulted in exacerbation of disease as shown by increased paw swelling, increased infiltration of inflammatory cells, increased bone remodelling and increased production of inflammatory mediators, as well as increased production of anti-citrullinated protein antibodies. Anti-IL-17 mAb treatment demonstrated that IL-17 is important for disease severity in both the presence and absence of Tregs, and that IL-17 blockade is able to rescue mice from the exacerbated disease caused by Tregdepletion and caused a reduction in RANKL, IL-6 and the number of neutrophils. We show that Tregsare important for the containment of inflammation and bone remodelling in DTHA. To our knowledge, this is the first study using theFoxp3-DTR-eGFPmouse on a C57BL/6 background for Tregdepletion in an arthritis model, and we here demonstrate the usefulness of the approach to study the role of Tregsand IL-17 in arthritis.

Rheumatoid arthritis-celiac disease relationship: joints get that gut feeling

Rheumatoid arthritis (RA) and celiac disease (CD) belong to the autoimmune disease family. Despite being separate entities they share multiple aspects. Epidemiologically they share comparable incidence environmental influences, associated antibodies and a recent incidental surge. They differ in their HLA pre-dispositions and specific predictive and diagnostic biomarkers. At the clinical level, celiac disease exhibits extra-intestinal rheumatic manifestations and RA gastrointestinal ones. Small bowel pathology exists in rheumatic patients. A trend towards responsiveness to a gluten free diet has been observed, ameliorating celiac rheumatic manifestations, whereas dietary interventions for rheumatoid arthritis remain controversial. Pathophysiologically, both diseases are mediated by endogenous enzymes in the target organs. The infectious, dysbiotic and increased intestinal permeability theories, as drivers of the autoimmune cascade, apply to both diseases. Contrary to their specific HLA pre-disposition, the diseases share multiple non-HLA loci. Those genes are crucial for activation and regulation of adaptive and innate immunity. Recently, light was shed on the interaction between host genetics and microbiota composition in relation to CD and RA susceptibility, connecting bugs and us and autoimmunity. A better understanding of the above mentioned similarities in the gut-joint inter-relationship, may elucidate additional facets in the mosaic of autoimmunity, relating CD to RA.