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Objective: The aim of this study was to investigate whether a shared genetic susceptibility exists between individuals with rheumatoid arthritis (RA) and individuals with myocardial infarction (MI)—including major MI risk factors—and to quantify the degree of any such overlap. Methods: Genome‐wide association study (GWAS) data for individuals with RA were constructed from a sample of 26,637 Swedish patients with RA and controls without RA. For patients with MI, GWAS data were obtained from a previously published meta‐analysis. Genome‐wide genetic correlation was estimated via linkage disequilibrium score regression. LAVA was employed to estimate local genetic correlations in ~2,500 nonoverlapping loci, including the major histocompatibility complex. The controls without RA were used for reference panel data. We also assessed stratified estimates of both genome‐wide and local genetic correlation based on subsamples of individuals with seropositive RA and those with seronegative RA. Furthermore, genome‐wide genetic correlation was estimated between RA and selected cardiovascular risk factors to elucidate pleiotropic relationships. Results: Following quality control, our GWAS of patients with RA consisted of 25,826 individuas. Genome‐wide genetic correlation between patients with RA and MI was estimated to 0.13 (95% confidence interval –0.03 to 0.29). Six regions exhibited significant local genetic correlation, though none harbored any known risk single‐nucleotide polymorphisms for either of the two traits. Estimates were similar in both individuals with seropositive RA and those with seronegative RA. No statistically significant genetic correlations were observed between RA risk factors and any of the MI risk factors. Conclusion: Our findings indicate that genetic overlap between patients with RA and MI is minor. Furthermore, genetic overlap between RA and MI risk factors seem unlikely to provide a major contribution to the increased risk of MI observed in patients with RA. [ABSTRACT FROM AUTHOR]

Objectives To investigate the influence of genetic factors on persistence with treatment of early RA with MTX monotherapy. Methods We conducted a genome-wide association study (GWAS) in a sample of 3902 Swedish early-RA patients initiating MTX in DMARD monotherapy as their first-ever DMARD. The outcome, short- and long-term MTX treatment persistence, was defined as remaining on MTX at 1 and at 3 years, respectively, with no additional DMARDs added. As genetic predictors, we investigated individual SNPs, and then calculated a polygenic risk score (PRS) based on SNPs associated with RA risk. The SNP-based heritability of persistence was estimated overall and by RA serostatus. Results No individual SNP reached genome-wide significance (P  < 5 × 10−8), either for persistence at 1 year or at 3 years. The RA PRS was not significantly associated with MTX treatment persistence at 1 year [relative risk (RR) = 0.98 (0.96–1.01)] or at 3 years [RR = 0.96 (0.93–1.00)]. The heritability of MTX treatment persistence was estimated to be 0.45 (0.15–0.75) at 1 year and 0.14 (0–0.40) at 3 years. The results in seropositive RA were comparable with those in the analysis of RA overall, while heritability estimates and PRS RRs were attenuated towards the null in seronegative RA. Conclusion Despite being the largest GWAS on an MTX treatment outcome to date, no genome-wide significant associations were detected. The modest heritability observed, coupled with the broad spread of suggestively associated loci, indicate that genetic influence is of polygenic nature. Nevertheless, MTX monotherapy persistence was lower in patients with a greater genetic disposition, per the PRS, towards RA. [ABSTRACT FROM AUTHOR]

Objective. We aimed to investigate if aberrant intracellular production of NADPH oxidase-derived reactive oxygen species (ROS) in neutrophils is a disease mechanism in the autoinflammatory disease SAPHO syndrome, characterized by synovitis, acne, pustulosis, hyperostosis and osteitis, as has previously been suggested based on a family with SAPHO syndrome-like disease. Methods. Neutrophil function was explored in a cohort of four patients with SAPHO syndrome, two of whom were sampled during both inflammatory and non-inflammatory phase. Intracellular neutrophil ROS production was determined by luminol-amplified chemiluminescence in response to phorbol myristate acetate. Results. Cells from all patients produced normal amounts of ROS, both intra- and extracellularly, when compared with internal controls as well as with a large collection of healthy controls assayed in the laboratory over time (showing an extensive inter-personal variability in a normal population). Further, intracellular production of ROS increased during the inflammatory phase. Neutrophil activation markers were comparable between patients and controls. Conclusion. Dysfunctional generation of intracellular ROS in neutrophils is not a generalizable feature in SAPHO syndrome. Secondly, serum amyloid A appears to be a more sensitive inflammatory marker than CRP during improvement and relapses in SAPHO syndrome. [ABSTRACT FROM AUTHOR]

Objective. T helper 17 (Th17) and mast cells produce IL-17A in RA and critically contribute to the pathogenesis of RA. However, the complete IL-17 cytokine profile in RA is unknown. The aim of the study was to systematically study the expression of IL-17 family cytokines in RA.Methods. The expression of all IL-17 cytokines in RA synovium and pannus as well as in the synovium of OA was determined using quantitative RT-PCR (qRT-PCR). IL-17A and IL-17B were immunostained. Peripheral blood neutrophils were analysed for IL-17B. The effect of IL-17B alone or in combination with TNF-α was tested in vitro on fibroblasts and endothelial cells.Results. In all tissues IL-17B was the most expressed IL-17 family cytokine, found in lining but most strongly expressed in human neutrophil elastase containing polymorphonuclear cells. This pattern was distinct from that of IL-17A, which was found in mast cell tryptase immunoreactive cells. Circulating neutrophils contained IL-17B, verifying the in vivo results. Fibroblasts up-regulated the expression of IL-17RB, a putative receptor of IL-17B, after TNF-α stimulation. IL-17B significantly enhanced TNF-α-induced production of G-CSF and IL-6 in fibroblasts.Conclusion. IL-17B, which is present in synovium, may contribute to the pathogenesis of RA. IL-17B can enhance the effects of TNF-α on the production of cytokines and chemokines that control immune cell trafficking and neutrophil homeostasis in the inflamed tissues. [ABSTRACT FROM PUBLISHER]