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RelA/MicroRNA-30a/NLRP3 signal axis is involved in rheumatoid arthritis via regulating NLRP3 inflammasome in macrophages

ABSTRACT: NLRP3 inflammasome plays an important role in the pathogenesis of rheumatoid arthritis (RA). However, the post-transcriptional regulation of NLRP3 expression by miRNA in synovial macrophages is still not well understood. The aim of the study is to elucidate the mechanisms of RA with the focus on miRNAs mediated post-transcriptional regulation of the NLRP3 inflammasome. Here, we used NLRP3-deficient mice (NLRP3KO) to cross with TNFα-transgenic mice (TNFTG) to generate NLRP3KO/TNFTG mice, and compared their joint phenotypes with those of their TNFTG and wild-type (WT) littermates at 5 months of age. In comparison to WT mice, articular bone volume and cartilage area are decreased, whereas inflammed area, eroded surface, ALP+ osteoblast number, TRAP+ osteoclast number, and the areas of RelA+F4/80+, Caspase-1+F4/80+, IL-1β+F4/80+ synoviocytes are increased in the TNFTG mice. Knockout of NLRP3 ameliorates joint inflammation and bone damage in TNFTG mice. Further, in TNFα-primed BMDMs, RelA positively regulates NLRP3 expression, but negatively regulates miR-30a. Additionally, miR-30a negatively mediates NLRP3 expression by directly binding to its 3ʹ UTR, suggesting a miR-30a-mediated feedforward loop acting on NLRP3. Finally, intra-articular injection of AAV-miR-30a inhibits NLRP3 inflammasome activation, reduces joint inflammation, and attenuates bone damage in TNFTG mice. Thus, RelA/miR-30a/NLRP3 signal axis is involved in RA through regulating NLRP3 Inflammasome in macrophages.

SUBMITTER: Yang Q

PROVIDER: S-EPMC8575917 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Toll-like receptor 4 (TLR4) is well known for activating the innate immune system; however, it is also highly expressed in adaptive immune cells, such as CD4+ T-helper 17 (Th17) cells, which play a key role in multiple sclerosis (MS) pathology. However, the function and governing mechanism of TLR4 in Th17 remain unclear. METHODS:The changes of TLR4 in CD4+ T cells from MS patients and experimental autoimmune encephalomyelitis (EAE) mice were tested. TLR4-deficient (TLR4-/-) naïve T cells were induced in vitro and transferred into Rag1-/- mice to measure Th17 differentiation and EAE pathology. DNA sequence analyses combining with deletion fragments and mutation analyses, chromatin immunoprecipitation (ChIP), and electrophoretic mobility shift assay (EMSA) were used to explore the mechanism of TLR4 signaling pathway in regulating Th17 differentiation. RESULTS:The levels of TLR4 were increased in CD4+ Th17 cells both from MS patients and EAE mice, as well as during Th17 differentiation in vitro. TLR4-/- CD4+ naïve T cells inhibited their differentiation into Th17, and transfer of TLR4-/- CD4+ naïve T cells into Rag1-/- mice was defective in promoting EAE, characterized by less demyelination and Th17 infiltration in the spinal cord. TLR4 signal enhanced Th17 differentiation by activating RelA, downregulating the expression of miR-30a, a negative regulator of Th17 differentiation. Inhibition of RelA activity increased miR-30a level, but decreased Th17 differentiation rate. Furthermore, RelA directly regulated the expression of miR-30a via specific binding to a conserved element of miR-30a gene. CONCLUSIONS:TLR4-/- CD4+ naïve T cells are inadequate in differentiating to Th17 cells both in vitro and in vivo. TLR4-RelA-miR-30a signal pathway regulates Th17 differentiation via direct binding of RelA to the regulatory element of miR-30a gene. Our results indicate modulating TLR4-RelA-miR-30a signal in Th17 may be a therapeutic target for Th17-mediated neurodegeneration in neuroinflammatory diseases.

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RelA/MicroRNA-30a/NLRP3 signal axis is involved in rheumatoid arthritis via regulating NLRP3 inflammasome in macrophages

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