Background/Introduction: Aberrant expression of Toll like receptors (TLR) plays a vital role in pathogenesis of rheumatoid arthritis (RA). Micro RNAs (miRs) could play important role in the related signaling pathways. The present study was undertaken to establish the link between miR-147 and TLR-7 in rat macrophages (in vitro) and in pristane (PS) induced arthritic rats.
Methodology: Dual luciferase assay was done to confirm the interaction between miR-147 and TLR-7. The effect of miR-147 on regulation of TLR-7 was done by RT-qPCR and Immunoblotting studies in rat macrophages (ATCC® CRL-2192TM) after treating them with miR-147 mimics and inhibitors. R-848 (Imiquimod) was used as TLR-7 stimulant, the mRNA and protein expression levels of IFN-β and TNF-α were recorded to determine the regulation of TLR-7. The levels of miR-147 and TLR-7 were evaluated during induction of rat bone marrow derived macrophage in the PS induced rat macrophages and spleens of methotrexate exposed rats. The miR-147 mimics was injected intraperitoneal to the PS treated rats and the severity of arthritis was studied.
Results: The study confirmed TLR-7 mRNA as the potential target of miR-147 in rats. Alterations in miR-147 by transfecting mimics or inhibitors in ATCC® CRL-2192TM cells exhibited suppression and amelioration of TLR-7 and cytokine expression. The alteration in expression of miR-147 was inversely correlated with expression of TLR-7 during bone marrow derived macrophages induction in PS exposed cells and spleens. The abnormal expression was reversed in spleens of methotrexate treated arthritic rats. The treatment of miR-147 mimic caused suppression in expression of TLR-7 and improved the severity of arthritis in PS induced arthritic rats.
Conclusions: MiR-147 inversely regulates the TLR-7 signaling by targeting TLR-7 itself both in vivo and in vitro. The study provides a novel approach for conditions involving abnormal TLR-7 expression in arthritis.
Keywords: Rheumatoid arthritis; TLR-7; miR-147; toll like receptors.