A Preliminary Study On The Colocalization Of MiR-574-5p With TLR7/8 In Cells And The Effects Of Inhibition Of MiR-574-5p-TLR7/8 Signaling On Lupus And Lupus Nephritis In A Line Of Lupus-prone Mice

MicroRNA(miRNA)is one small non-coding RNA that is well known to serve as epigenetic regulators of gene expression by targeting the 3’-untranslated region of messenger RNA(mRNA),thereby causing mRNA degradation and suppression of translation.A few recent studies,however,revealed an unconventional role for miRNAs,i.e.,to act as ligands or agonists for the endosomal ssRNA sensing Toll-like receptors(mTlr7/hTLR8).In cancer cells,it was recently demonstrated that tumor cell exosome-derived miR-21 and miR-29a were capable of binding with mTlr7/hTLR8,thereby promoting TLR signaling and inducing inflammatory responses.However,the function of miRNA in autoimmunity,and particularly in systemic lupus erythematosus(SLE)remains poorly elucidated.B6.MRL-Faslpr/J mice is a gentic mouse model of SLE characterized by autoantibody production,lymphosplenomegaly,and glomerulonephritis.Here,through immunofluorescence(IF),we demonstrated that miR-574-5p can bind with mouse mTlr7 and human hTLR8.MiR-574-5p was obviously increased in the serum and other tissues of SLE mice,whereas in vivo silencing of miR-574-5p using a lentivirus carrying shRNA for miR-574-5p ameliorates inflammatory in mice.The concentrations of the serum cytokines of TNF-a/IL-6 were lower.And the renal fibrosis,renal IgG deposit and macrophge in tissues were also significantly ameliorated following in vivo knockdown of miR-574-5p.Moreover,In vivo supression of miR-574-5p also greatly improved the lupus-associated Spt-GC formation.In this case,we desighed ssRNAs which were modified with Locked Nucleic Acid(LNA)to silence the miR-574-5p in B6.MRL-Faslpr/J mice.Finally,we found LNA-antimiR-574-5p can knockdown miR-574-5p and ameliorated the splenomegaly in mice.The levels TNF-a and IL-6 in serum were decreasing.In addition,the percentage of Tc cells,Tfh cells and GC B cells were reduced.In summary,our data establish that miR-574-5p is a self-ligand for mTlr7/hTLR8 and the miR-574-5p-mTlr7/hTLR8 signaling is an important axis of immune and inflammatory responses.miR-574-5p might become a valuable target for the development of immunotherapeutic drugs for the prevention or treatment of diseases including viral infection,cancers and autoimmune disorders.