MicroRNA-146a (miR-146a) has been shown to play an important role in the regulation of inflammatory innate immune responses, and found to be differentially expressed in rheumatoid arthritis (RA). Through NF-κB pathway, this molecule is able to stimulate the release of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-17. It has been also suggested that single-nucleotide polymorphisms (SNPs) in miRNA sequences may alter miRNA expression and that miR-146a rs2910164 SNP may contribute to RA development. These observations prompted us to analyze the potential associations between the miR-146a-3p (rs2910164, G > C) and NFkB1 (rs28362491, ins/del ATTG) polymorphisms and miR-146a-5p expression in patients’ sera in relation to clinical outcome of the treatment as well as predisposition to RA. Genotyping was performed in 111 patients and 130 healthy individuals while 16 controls and 13 RA patients (before and after three months of therapy with TNF-α inhibitors (TNFi)) were studied for the circulating miR-146a-5p serum expression level. Patients carrying the NFkB1 ins/ins genotype were characterized by worse response to TNFi treatment (p = 0.023). In patients, before TNFi therapy, expression levels of miR-146a-5p were less (0.422 ± 0.171) as compared to those detected after three months of treatment (1.809 ± 0.658, p = 0.033) and observed for healthy controls (5.302 ± 2.112, p = 0.048). Moreover, patients with higher circulating miR-146a-5p levels after three months of TNFi administration were more frequently carrying the rs2910164-C allele (p = 0.032). These results support the hypothesis that miR-146a might be involved in pathogenesis of RA and imply that miR-146a-3p polymorphism may be associated with miR-146a-5p levels in serum after anti-TNF-α treatment.

Background and objectivesSystemic sclerosis (SSc) is a chronic multisystem autoimmune disease characterised by skin and  internal organs fibrosis and immune abnormalities. Recent evidence suggests that activated circulating monocytes from SSc patients play a role in SSc pathogenesis due to enhanced expression of tissue inhibitor of metalloproteinases 1 (TIMP-1), IL-8 and reactive oxygen species (ROS) induction, which contribute to fibrosis progression and chronic inflammation. The exact factors driving TIMP-1, IL-8 and ROS secretion are still unknown.The aim of this study was to investigate the expression pattern of profibrotic IL-8, TIMP-1, AP1 transcription factor-Fra2 and ROS induction in peripheral blood monocytes following DZNep (histone methyltransferase inhibitor) and TLR8 agonist (ssRNA) stimulation.Materials and methodsThe expression of Fra2, IL-8 and TIMP-1 and anti-oxidant superoxide dismutase 1 (SOD1) was measured by qRT-PCR in stimulated and unstimulated HC (n = 14) and SSc (n = 17) monocytes. Generation of ROS was determined using luciferase based assay. Fra2 DNA-binding activity was measured in AP-1 transcription assay in monocytic U937 cell line following epigenetic and TLR8 modifications. The level of anti-fibrotic miRNA-5196, which is predicted to bind and inhibit 3’UTR of Fra-2 gene, was also determined in HC and SSc monocytes.ResultsCombination of DZNep+TLR8 enhanced Fra2 (2-fold, p = 0.02), TIMP-1 (2-fold) and IL-8 (7.87-fold, p < 0.001) expression in SSc monocytes. Fra2 DNA-binding activity was 1.5-fold increased upon stimulation. Secreted level of TIMP-1 was 1.46-fold higher in SSc monocytes compared to unstimulated cells. Generated ROS was 2.21-fold (p = 0.0395) higher following DZNep+TLR8 stimulation in monocytic U937 cells. In contrast, miRNA-5196 expression was 2.13-fold decreased in SSc monocytes upon DZNep+TLR8 stimulation. Also the level of SOD1 was decreased in HC and SSc monocytes following stimulation, 2.16-fold (p = 0.025) and 1.56-fold, respectively.ConclusionsThese data suggest that DZNep and TLR8 agonist are able to enhance pro-fibrotic TIMP-1, IL-8 and oxidative stress generation. As opposed by the decrease of anti-fibrotic miRNA-5196 and anti-oxidant SOD1 expression in SSc monocytes, which might be used as a potential modulators of fibrogenesis in SSc.Supported by Homing Plus grant/2013–8/4 from Foundation for Polish Science and UMO-2015/16/S/NZ6/00041 from National Science Centre, Poland.