Osteopontin (OPN) is a bone-derived phosphoglycoprotein related to physiological and pathological mechanisms that nowadays has gained relevance due to its role in the immune system response to chronic degenerative diseases, including rheumatoid arthritis (RA) and osteoarthritis (OA). OPN is an extracellular matrix (ECM) glycoprotein that plays a critical role in bone remodeling. Therefore, it is an effector molecule that promotes joint and cartilage destruction observed in clinical studies, in vitro assays, and animal models of RA and OA. Since OPN undergoes multiple modifications, including posttranslational changes, proteolytic cleavage, and binding to a wide range of receptors, the mechanisms by which it produces its effects, in some cases, remain unclear. Although there is strong evidence that OPN contributes significantly to the immunopathology of RA and OA when considering it as a common denominator molecule, some experimental trial results argue for its protective role in rheumatic diseases. Elucidating in detail OPN involvement in bone and cartilage degeneration is of interest to the field of rheumatology. This review aims to provide evidence of the OPN’s multifaceted role in promoting joint and cartilage destruction and propose it as a common denominator of AR and OA immunopathology.

Objective. To evaluate whether serum titers of second-generation anticyclic citrullinated peptide antibodies (anti-CCP2) are associated with the severity and extent of interstitial lung disease in rheumatoid arthritis (RA-ILD).Methods. In across-sectional study, 39 RA-ILD patients confirmed by high-resolution computed tomography (HRCT) were compared with 42 RA without lung involvement (RA only). Characteristics related to RA-ILD were assessed in all of the patients and serum anti-CCP2 titers quantified.Results. Higher anti-CCP2 titers were found in RA-ILD compared with RA only (medians 77.9 versus 30.2 U/mL,P<0.001). In the logistic regression analysis after adjustment for age, disease duration (DD), smoke exposure, disease activity, functioning, erythrocyte sedimentation rate, and methotrexate (MTX) treatment duration, the characteristics associated with RA-ILD were higher anti-CCP2 titers (P=0.003) and + RF (P=0.002). In multivariate linear regression, the variables associated with severity of ground-glass score were anti-CCP2 titers (P=0.02) and with fibrosis score DD (P=0.01), anti-CCP2 titers (P<0.001), and MTX treatment duration (P<0.001).Conclusions. Anti-CCP2 antibodies are markers of severity and extent of RA-ILD in HRCT. Further longitudinal studies are required to identify if higher anti-CCP2 titers are associated with worst prognosis in RA-ILD.

Autoimmune rheumatic diseases are a cluster of heterogeneous disorders that share some clinical symptoms such as pain, tissue damage, immune deregulation, and the presence of inflammatory mediators. Biologic disease-modifying antirheumatic drugs are some of the most effective treatments for rheumatic diseases. However, their molecular and pharmacological complexity makes them potentially immunogenic and capable of inducing the development of anti-drug antibodies. TNF inhibitors appear to be the main contributors to immunogenicity because they are widely used, especially in rheumatoid arthritis. Immunogenicity response on these treatments is crucial since the appearance of ADAs has consequences in terms of safety and efficacy. Therefore, this review proposes an overview of the immunogenicity of biological agents used in autoimmune rheumatic diseases highlighting the prevalence of anti-drug antibodies.

The main cause of death in rheumatoid arthritis (RA) is cardiovascular events. We evaluated the relationship of anticyclic citrullinated peptide (anti-CCP) antibody levels with increased carotid intima-media thickness (cIMT) in RA patients.Methods. Forty-five anti-CCP positive and 37 anti-CCP negative RA patients, and 62 healthy controls (HC) were studied. All groups were assessed for atherogenic index of plasma (AIP) and cIMT. Anti-CCP, C-reactive protein (CRP), and levels of tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay (ELISA).Results. The anti-CCP positive RA patients showed increased cIMT compared to HC and anti-CCP negative (P<0.001). Anti-CCP positive versus anti-CCP negative RA patients, had increased AIP, TNFαand IL-6 (P<0.01), and lower levels of high density lipoprotein cholesterol (HDL-c) (P=0.02). The cIMT correlated with levels of anti-CCP (r=0.513,P=0.001), CRP (r=0.799,P<0.001), TNFα(r=0.642,P=0.001), and IL-6 (r=0.751,P<0.001). In multiple regression analysis, cIMT was associated with CRP (P<0.001) and anti-CCP levels (P=0.03).Conclusions. Levels of anti-CCP and CRP are associated with increased cIMT and cardiovascular risk supporting a clinical role of the measurement of cIMT in RA in predicting and preventing cardiovascular events.