Mice with miR-146a deficiency develop severe gouty arthritis via dysregulation of TRAF 6, IRAK 1 and NALP3 inflammasome

Abstract

BackgroundMicroRNAs (miRNAs) serve as important regulators of inflammatory and immune responses and are implicated in several immune disorders including gouty arthritis. The expression of miR-146a is upregulated in the peripheral blood mononuclear cells of patients with inter-critical gout when compared to normouricemic and hyperuricemic controls and those patients with acute gout flares. However, the role of miR-146a in the development of gout remains unknown. Here, we used miR-146a knockout (KO) mice to test miR-146a function in a monosodium urate (MSU)-induced gouty arthritis model.MethodsThe footpad or ankle joint of miR-146a KO and wild-type (WT) mice were injected with an MSU suspension to induce acute gouty arthritis. Bone marrow-derived macrophages (BMDMs) were stimulated with MSU and the gene expression of miR-146a; interleukin 1 beta (IL-1β); tumor necrosis factor-α (TNF-α); and the NACHT, LRR and PYD domains-containing protein 3 (NALP3) inflammasome was evaluated. TNF-α and IL-1β protein levels in BMDMs were assessed by fluorescence-activated cell sorting and western blot analyses. Gene and protein levels of TNF receptor-associated factor 6 (TRAF6) and IL-1 receptor-associated kinase (IRAK1), the targets of miR-146a, were also measured.ResultsSignificantly increased paw swelling and index and ankle joint swelling were observed in miR-146a KO mice compared to WT controls after MSU treatment. MiR-146a expression in BMDMs from WT mice was dramatically upregulated at 4 h following MSU stimulation. Additionally, the expression of IL-1β, TNF-α, and NALP3 was higher in BMDMs from miR-146a KO mice after exposure to MSU crystals compared to those from WT mice. Consistent with the observed gene expression, the IL-1β and TNF-α proteins were upregulated in miR-146a KO mice. Additionally quantitative RT-PCR and western blot demonstrated that TRAF6 and IRAK1 were dramatically upregulated in BMDMs from miR-146 KO mice compared to those from WT mice.ConclusionsCollectively, these observations suggest that miR-146a provides negative feedback regulation of gouty arthritis development and lack of miR-146a enhances gouty arthritis via upregulation of TRAK6, IRAK-1, and the NALP3 inflammasome function.

Resolvin D1 suppresses pannus formation via decreasing connective tissue growth factor caused by upregulation of miRNA-146a-5p in rheumatoid arthritis

“…MiRNA-146a was also known as a major molecular regulator in arthritis. Mice with miRNA-146a deficiency are more likely to develop severe gouty arthritis [33]. What is more, miRNA-146a could inhibit pathogenic bone erosion in inflammatory arthritis [34].…”

Cortical Neurotoxic Astrocytes with Early ALS Pathology and miR-146a Deficit Replicate Gliosis Markers of Symptomatic SOD1G93A Mouse Model

“…Accordingly, our preliminary data on the benefits of miR-146a upregulation indicated a reduction in aberrancy ALS astrocyte biomarkers (data not shown). Indeed, miR-146a was shown to act as a negative-feedback regulator of the inflammatory pathway, and to directly target IRAK1 and TRAF6, both downstream components of the TLR cascade and mediators of inflammation via NF-kB activation [90,48]. Other studies revealed that miR-146a by downregulating IRAK1 and TRAF6 in macrophages reduced the production of pro-inflammatory cytokines [91].…”

Dysregulation of Inflammasome Priming and Activation by MicroRNAs in Human Immune-Mediated Diseases

“…Overexpression of miR-302b-3p directly downregulates IRAK4 and thereby inhibits NLRP3 expression (63). Another research group investigated the function of miR-146a-5p in response to MSU stimulation (64). The mRNA and protein expression of TRAF6, IRAK1 and downstream NLRP3, ASC, and caspase-1 were upregulated in MSU-induced bone marrow-derived macrophages of miR-146a-5p knockout mice as compared with wild-type mice.…”