Effects of microRNA-146a on the proliferation and apoptosis of human osteochondrocytes by targeting TRAF6 through the NF- κB signalling pathway

Circulating miR-146b and miR-27b are efficient biomarkers for early diagnosis of Equidae osteoarthritis

One of the most orthopedic problems seen in the equine is osteoarthritis (OA). The present study tracks some biochemical, epigenetic, and transcriptomic factors along different stages of monoiodoacetate (MIA) induced OA in donkeys in serum and synovial fluid. The aim of the study was the detection of sensitive noninvasive early biomarkers. OA was induced by a single intra-articular injection of 25 mg of MIA into the left radiocarpal joint of nine donkeys. Serum and synovial samples were taken at zero-day and different intervals for assessment of total GAGs and CS levels as well as miR-146b, miR-27b, TRAF-6, and COL10A1 gene expression. The results showed that the total GAGs and CS levels increased in different stages of OA. The level of expression of both miR-146b and miR-27b were upregulated as OA progressed and then downregulated at late stages. TRAF-6 gene was upregulated at the late stage while synovial fluid COL10A1 was over-expressed at the early stage of OA and then decreased at the late stages (P < 0.05). In conclusion, both miR-146b and miR-27b together with COL10A1 could be used as promising noninvasive biomarkers for the very early diagnosis of OA.

miRNAs' Cross-Involvement in Skin Allergies: A New Horizon for the Pathogenesis, Diagnosis and Therapy of Atopic Dermatitis, Allergic Contact Dermatitis and Chronic Spontaneous Urticaria

Skin inflammation is a common underlying feature of atopic dermatitis, allergic contact dermatitis and chronic spontaneous urticaria. The pathogenetic mechanisms have not been fully elucidated. The purpose of this study was to examine whether miRNA, by regulating inflammatory mechanisms through the modulation of innate and adaptive immune responses, could play a major role in the pathogenesis of these skin conditions. We conducted a narrative review using the Pubmed and Embase scientific databases and search engines to find the most relevant miRNAs related to the pathophysiology, severity and prognosis of skin conditions. The studies show that miRNAs are involved in the pathogenesis and regulation of atopic dermatitis and can reveal an atopic predisposition or indicate disease severity. In chronic spontaneous urticaria, different miRNAs which are over-expressed during urticaria exacerbations not only play a role in the possible response to therapy or remission, but also serve as a marker of chronic autoimmune urticaria and indicate associations with other autoimmune diseases. In allergic contact dermatitis, miRNAs are upregulated in inflammatory lesions and expressed during the sensitization phase of allergic response. Several miRNAs have been identified as potential biomarkers of these chronic skin conditions, but they are also possible therapeutic targets.

Exosomal circ-BRWD1 contributes to osteoarthritis development through the modulation of miR-1277/TRAF6 axis

Background

Circular RNAs (circRNAs) can act as vital players in osteoarthritis (OA). However, the roles of circRNAs in OA remain obscure. Herein, we explored the roles of exosomal circRNA bromodomain and WD repeat domain containing 1(circ-BRWD1) in OA pathology.

Methods

In vitro model of OA was constructed by treating CHON-001 cells with interleukin-1β (IL-1β). Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used for circ-BRWD1, BRWD, miR-1277, and TNF receptor-associated factor 6 (TRAF6) levels. RNase R assay was conducted for the feature of circ-BRWD1. Transmission electron microscopy (TEM) was employed to analyze the morphology of exosomes. Western blot assay was performed for protein levels. Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis, and 5-Ethynyl-2′-deoxyuridine (EDU) assay were adopted for cell viability, apoptosis, and proliferation, respectively. Enzyme-linked immunosorbent assay (ELISA) was carried out for the concentrations of interleukin-6 (IL-6) and interleukin-8 (IL-8). Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to analyze the interaction between miR-1277 and circ-BRWD1 or TRAF6.

Results

Circ-BRWD1 was increased in OA cartilage tissues, IL-1β-treated CHON-001 cells, and the exosomes derived from IL-1β-treated CHON-001 cells. Exosome treatment elevated circ-BRWD1 level, while exosome blocker reduced circ-BRWD1 level in IL-1β-treated CHON-001 cells. Silencing of circ-BRWD1 promoted cell viability and proliferation and repressed apoptosis, inflammation, and extracellular matrix (ECM) degradation in IL-1β-stimulated CHON-001 cells. For mechanism analysis, circ-BRWD1 could serve as the sponge for miR-1277 to positively regulate TRAF6 expression. Moreover, miR-1277 inhibition ameliorated the effects of circ-BRWD1 knockdown on IL-1β-mediated CHON-001 cell damage. Additionally, miR-1277 overexpression relieved IL-1β-induced CHON-001 cell injury, while TRAF6 elevation restored the impact.

Conclusion

Exosomal circ-BRWD1 promoted IL-1β-induced CHON-001 cell progression by regulating miR-1277/TRAF6 axis.

MicroRNA-146a-Mediated IL-6/Signal Transducer and Activator of Transcription 3 Signaling Pathway in Chondrocyte Proliferation and Apoptosis in Mice with Osteoarthritis

Background: To investigate the MicroRNA-146a targeting regulation of IL-6/STAT3 signaling pathway activity and influence the proliferation and apoptosis behavior-related mechanisms of OA chondrocytes. Material and Methods: 10 C57 mice were isolated and cultured with membrane protease and type II collagenase. The experiment was divided into blank group, MicroRNA-146a overexpression group and low expression group. The chondrocytes were transfected with plasmid vector. After 48 hours of culture, the proliferation rate of chondrocytes was detected by MTT method. The levels of type ii collagen, MMP-9, IL-1, IL-6, and TNF-α in culture medium were detected by ELISA. Luciferase reported experimental analysis of MircoRNA-146a targeting regulation of IL-6 genes. Results: Compared with the blank group, the proliferation rate of chondrocytes in the overexpression group was significantly decreased, the apoptosis rate was increased, the levels of IL-6 and p-STAT3 protein, type II collagen, MMP-9, IL-1, IL-6 and TNF-α were increased, while the low expression group was correlated (P < 0.05). Luciferase reporter experiments confirmed that MicroRNA-146a had a better binding effect with the IL-6 gene. Conclusion: MicroRNA-146a overexpression may mediate activation of IL-6/STAT3 signaling pathway and participate in decreased proliferation activity and increased apoptosis activity in OA chondrocytes. IL-6 gene may have targeted regulatory sites for MicroRNA-146a.

Knockdown of TRAF6 inhibits chondrocytes apoptosis and inflammation by suppressing the NF-κB pathway in lumbar facet joint osteoarthritis

Tumor necrosis factor receptor-associated factor 6 (TRAF6), a regulator of NF-κB signaling, has been discovered recently to be probably related to osteoarthritis, while the function of TRAF6 in lumbar facet joint osteoarthritis(FJOA)still remains unknown. The aim of this study was to probe the specific function of TRAF6 in chondrocytes and its connection with the pathophysiology of FJOA. We found upregulation of TRAF6 in FJOA cartilage by western blot analysis. In vitro, we stimulated immortalized human chondrocytes by LPS to establish the cells apoptosis model. Western blot analysis demonstrated that levels of TRAF6 and cleaved caspase-3/8 in the chondrocyte injury model increased significantly. Knockdown of TRAF6 suppressed the expression of matrix metallopeptidase-13 (MMP-13) and interleukin-6 (IL-6) induced by LPS, and alleviated cell apoptosis. Meanwhile, western blot and immunofluorescent staining demonstrated that IκBα degradation and p65 nuclear transportation were also inhibited, revealing that knockdown of TRAF6 suppressed activation of the NF-κB pathway in LPS-induced chondrocytes apoptosis model. Collectively, our findings suggest that TRAF6 plays a crucial role in FJOA development by regulating NF-κB signaling pathway. Knockdown of TRAF6 may supply a potential therapeutic strategy for FJOA.

Correlations between microRNA-146a and immunoglobulin and inflammatory factors in Guillain-Barré syndrome

Objective

To study correlations between expression of microRNA-146a (miR-146a) and immunoglobulin and inflammatory cytokines in serum of patients with Guillain–Barré syndrome (GBS).

Methods

Eighty-four patients with GBS were selected as the experimental group and 50 healthy individuals as controls. Reverse transcription-PCR was used to detect expression of miR-146a in peripheral blood of all participants. Immunoturbidometric assay was used to detect immunoglobulins (Ig)G, IgA, and IgM in peripheral blood of all participants. The levels of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor α (TNF-α) were measured by ELISA in peripheral blood. The expression of miR-146a was compared between the two groups and Pearson correlation analysis was used to analyze correlations between miR-146a and immunoglobulin and inflammatory factors.

Results

Expression of miR-146a was higher in the GBS group than in controls. Expression of IL-6, CRP, TNF-α, and IgG was significantly higher in the GBS group than in controls. miR-146a was significantly and positively correlated with IL-6, CRP, TNF-α, and IgG but not with IgA and IgM.

Conclusion

The expression profile of miR-146a in patients with GBS differs from that in healthy individuals. Thus, miR-146a may participate in the pathogenesis of GBS by regulating immune and inflammatory responses.

MiR-21-5p regulates extracellular matrix degradation and angiogenesis in TMJOA by targeting Spry1

BACKGROUND

Due to the lack of research on the pathological mechanism of temporomandibular joint osteoarthritis (TMJOA), there are few effective treatment measures in the clinic. In recent years, microRNAs (miRs) have been demonstrated to play an important role in the pathogenesis of osteoarthritis (OA) by regulating a variety of target genes, and the latest evidence shows that miR-21-5p is specifically overexpressed in OA. The purpose of this project was to clarify whether miR-21-5p can regulate the TMJOA process by targeting Spry1.

METHODS

TMJOA was induced by a unilateral anterior crossbite (UAC) model, and the effect of miR-21-5p knockout on TMJOA was evaluated by toluidine blue (TB), immunohistochemical (IHC) staining, Western blotting (WB) and RT-qPCR. Primary mouse condylar chondrocytes (MCCs) were isolated, cultured and transfected with a series of mimics, inhibitors, siRNA-Spry1 or cDNA Spry1. WB, RT-qPCR, IHC and TB were used to detect the effect of miR-21-5p and its target gene Spry1 on the expression of MMP-13, VEGF and p-ERK1/2 in TMJOA. The effect of miR-21-5p on angiogenesis was evaluated by chick embryo chorioallantoic membrane (CAM) assay and WB.

RESULTS

In the UAC model, the cartilage thickness and extracellular matrix of miR-21-5p knockout mice were less damaged, and miR-21-5p and UAC model were shown to affect the expression of Spry1, IL-1β, MMP-13, and VEGF. Luciferase experiments confirmed that Spry1 was the direct target of miR-21-5p. The expression levels of Spry1, MMP-13, VEGF and p-ERK1/2 in MCCs transfected with miR-21-5p mimic were higher than those in the inhibitor group. Under the simulated inflammatory environment of IL-1β, the expression levels of MMP-13, VEGF and p-ERK1/2 were positively correlated with miR-21-5p, while Spry1 was negatively correlated with miR-21-5p. Inhibition of miR-21-5p expression and overexpression of Spry1 enhanced the inhibition of MMP-13, VEGF and p-ERK1/2 expression. MiR-21-5p had a significant role in promoting angiogenesis in the chick embryo CAM assay, and this role was clearly mediated by the ERK-MAPK signalling pathway.

CONCLUSION

This study verified that miR-21-5p can promote the process of TMJOA by targeting Spry1, which provides a new direction for future research on the treatment of this disease.

Anti-inflammatory effects of miRNA-146a induced in adipose and periodontal tissues

MicroRNA (miRNA) plays an important role in diverse cellular biological processes such as inflammatory response, differentiation and proliferation, and carcinogenesis. miR-146a has been suggested as a negative regulator of the inflammatory reaction. Although, it has been reported as expressed in inflamed adipose and periodontal tissues, however, miR-146a's inhibitory effects against inflammatory response in both the tissues, are not well understood. Therefore, in this study, the inhibitory effects of miR-146a on both adipose and periodontal inflammation, was investigated. In vitro study has revealed that miR-146a transfection into either adipocytes or gingival fibroblasts, has resulted in a reduced cytokine gene expression, observed on co-culturing the cells with macrophages in the presence of lipopolysaccharides (LPS), in comparison to the control miRNA transfected. Similarly, miR-146a transfection into macrophages resulted in a reduced expression of TNF-α gene and protein in response to LPS stimulation. In vivo study revealed that a continuous intravenous miR-146a administration into mice via tail vein, protected the mice from developing high-fat diet-induced obesity and the inflammatory cytokine gene expression was down-regulated in both adipose and periodontal tissues. miR-146a appeared to be induced by macrophage-derived inflammatory signals such as TNF-α by negative feed-back mechanism, and it suppressed inflammatory reaction in both adipose and periodontal tissues. Therefore, miR-146a could be suggested as a potential therapeutic molecule and as a common inflammatory regulator for both obesity-induced diabetes and related periodontal diseases.

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miR-146a induced by adipose and periodontal inflammation via macrophage mediators.

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miR-146a is a negative inflammation regulator in adipose and periodontal tissues.

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miR-146a is a potential therapeutic target against obesity and periodontal diseases.

Impact of miR-SNP rs2910164 on miR-146a expression in osteoarthritic chondrocytes

PURPOSE

MiR-146a acts as a negative inflammatory mediator in different diseases and has been implicated in osteoarthritis (OA) pathogenesis. In our study, we investigated the association between miR-SNP rs2910164 and OA susceptibility and its role on the expression of miR-146a, inflammatory and catabolic mediators in osteoarthritic chondrocytes.

MATERIALS AND METHODS

Genetic association analysis was performed in 1688 knee OA patients and healthy individuals of Greek origin. Genomic DNA was extracted from blood and genotyped for rs2910164 (G > C) using Restriction-Fragment Length Polymorphism (RFLP). Total RNA was extracted from chondrocytes of 18 OA patients and miR-146a, IL-1 Receptor-Associated Kinase 1 (IRAK-1), TNF Receptor-Associated Factor 6 (TRAF-6), A Disintegrin and Metalloproteinase with Thrombospondin Motifs 5 (ADAMTS-5), Matrix Metalloproteinase-13 (MMP-13), Interleukin-6 (IL-6), Interleukin-1 Beta (IL-1β) and Tumor Necrosis Factor-Alpha (TNF-α) expression was evaluated using quantitative Real-Time PCR (qRT-PCR).

RESULTS

OA patients carrying rs2910164-GC and CC genotypes did not have an increased risk for OA development compared to GG genotype carriers. MiR-146a expression in OA chondrocytes was significantly lower in patients with rs2910164-GC genotype than in the GG carriers. OA patients carrying the rs2910164-GC genotype in their chondrocytes exhibited increased IRAK-1, TRAF-6, MMP-13, IL-1β and IL-6 expression levels compared with rs2910164-GG carriers.

CONCLUSION

We demonstrate, for the first time, that miR-SNP rs2910164 in miR-146a gene is associated with reduced miR-146a and increased inflammatory and catabolic mediators' expression in OA chondrocytes. Our data imply that genetic variations in miRNAs linked to OA pathogenesis may regulate their expression levels, suggesting new therapeutic strategies for patients with cartilage diseases.

The synergistic function of miR-140-5p and miR-146a on TLR4-mediated cytokine secretion in osteoarthritic chondrocytes

ΜiR-140-5p and miR-146a regulate inflammatory pathways including TLR4/NF-κB signaling and have been found to be involved in OA pathogenesis. In this study, we investigated the effect of the synergistic function of miR-140-5p and miR-146a on inflammation mediated by TLR4 in ΟΑ chondrocytes. Bioinformatics analysis revealed that TLR4 was the only common OA-related target gene of miR-140-5p and miR-146a, located in the sub-network with the highest MCODE score; it also showed that the target genes of miR-140-5p and miR-146a which located in MCODE sub-networks were enriched in OA-related biological processes and pathways. Overexpression of miR-140-5p or miR-146a and combined miR-140-5p/miR-146a overexpression in OA chondrocytes demonstrated that combined treatment had the strongest negative effect on TLR4 expression. Moreover, simultaneous overexpression of miR-140-5p and miR-146a resulted in the highest reduction of NF-κΒ phosphorylation levels, as well as IL-1b, IL-6 and TNFa expression levels in OA chondrocytes as compared to the reductions observed when either miR-140-5p or miR-146a was overexpressed. Our results, therefore, demonstrate for the first time, that the synergistic function of miR-140-5p and miR-146a have a strong protective effect against inflammatory mediators' production in OA chondrocytes through targeting the TLR4/NF-κB signaling.

MicroRNA‑146a as a potential regulator involved in the pathogenesis of atopic dermatitis

Previous studies have demonstrated that microRNA (miR)‑146a is involved in the inflammatory response of atopic dermatitis (AD). The aim of the present study was to investigate the expression of miR‑146a in the serum of patients with AD and in skin lesions of AD animal models. In addition, we aimed to predict and verify the target genes of miR‑146a. miR‑146a expression was measured in AD patient serum via reverse transcription‑quantitative PCR. T‑helper (Th)1 [CD4+; interferon (IFN)‑γ+] and Th2 [CD4+; interleukin (IL)‑4+] expression in peripheral blood mononuclear cells was evaluated using flow cytometry. Following the establishment of a 2,4‑dinitrofluorobenzene‑induced C57BL/6 mouse AD model, Th1 (CD4+IFN‑γ+) and Th2 (CD4+IL‑4+) expression was analyzed in murine spleen cells via flow cytometry. Plasmids were transfected into 293T cells and at 48 h post‑transfection, cells were analyzed using a luciferase assay system. The results revealed that the AD group had a significantly lower Th1/Th2 ratio and a significantly higher miR‑146a expression compared with the control group (P<0.05). Furthermore, a decreased Th1/Th2 ratio and a significantly increased miR‑146a expression were observed in the model group compared with the control group (P<0.01). We also conducted a dual‑luciferase assay to determine whether small ubiquitin‑related modifier 1 (SUMO1) if the target gene of miR‑146a. We observed a ~30% decrease in the relative luciferase activity in cells containing the 3'‑untranslated region of SUMO1 + miR‑146a). The results of the luciferase assay indicated that may be a direct mRNA target of miR‑146a; however, the quantification of band density of SUMO1 expression following western blotting did not significantly differ. The development of animal models in AD research is of vital importance. The results revealed that miR‑146a may be a potential regulator involved in the pathogenesis of AD. Furthermore, the current study determined that miR‑146a could be a valuable marker of AD and thus, may be applied in the development of therapeutic strategies for treating AD.

miR-21-5p protects IL-1β-induced human chondrocytes from degradation

OBJECTIVE

Osteoarthritis (OA) is a prevalent degenerative disease caused by various factors. MicroRNAs are important regulators in OA. MiR-21-5p expression is decreased in OA cartilage, but the effects of modulating miR-21-5p on cartilage regeneration are unknown. Therefore, our aim was to investigate the effects of miR-21-5p on cartilage metabolism of OA chondrocytes.

DESIGN

We used IL-1β (10 ng/ml) to mimic OA chondrocytes. OA chondrocytes were transfected with miR-21-5p, the gene expression of COL2A1, MMP13, and ADAMTS5 was detected by qPCR. At the same time, COL2A1, MMP13, and ADAMTS5 were analyzed at the protein level by Western blot. CCK8 measured the cell's viability and SA-β-gal detected the cell's senescence.

RESULTS

Upregulation of miR-21-5p had increased COL2A1 expression and decreased MM P13 and ADAMTS5 expression, which were in accord with Western blot data. SA-β-gal activity significantly increased, the viability was decreased in OA chondrocytes, and upregulation of miR-21-5p can decrease the SA-β-gal activity and increase cell viability.

CONCLUSION

MiR-21-5p might be a potential disease-modifying compound in OA, as it promotes hyaline cartilage production. These results provided that novel insights into the important function in OA pathological development.

Long noncoding RNA CHRF exacerbates IL-6-induced inflammatory damages by downregulating microRNA-146a in ATDC5 cells

Osteoarthritis (OA) is a frequent chronic musculoskeletal disorder which lacks applicably effective therapeutic strategy. In this study, we attempted to investigate whether long noncoding RNA (lncRNA) cardiac hypertrophy-related factor (CHRF) participated in mediating interleukin-6 (IL-6)-induced in vitro inflammatory damages as well as the regulatory mechanisms. ATDC5 cells were stimulated with IL-6, and then cellular damages were evaluated on the basis of cell viability by CCK-8, apoptotic cells by observation with flow cytometry, apoptosis-associated proteins by western blot analysis, and accumulation of inflammatory factors by quantitative reverse transcription polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and western blot analysis. Then, effects of lncRNA CHRF on IL-6-treated cells were evaluated. We further explored the downstream factor of lncRNA CHRF and demonstrated whether lncRNA CHRF functioned through the downstream factor. Afterwards, crucial signaling cascades were anatomized. We found that IL-6 reduced cell viability, elevated apoptosis, induced upregulation of inflammatory factors, as well as upregulated lncRNA CHRF and down-regulated miR-146a expression. Then, we found lncRNA CHRF overexpression aggravated IL-6-induced alterations, and lncRNA CHRF knockdown showed the opposite effects. Furthermore, miR-146a was identified to be negatively regulated by lncRNA CHRF, and its overexpression abrogated the roles of lncRNA CHRF in IL-6-treated cells. IL-6-induced the accumulation of IκBα, p65, JAK1, and STAT3 at phosphorylated level was further facilitated by lncRNA CHRF whereas repressed by miR-146a. In conclusion, lncRNA CHRF aggravated the IL-6-induced inflammatory damages in ATDC5 cells. We further outlined a possible mechanism that through downregulating miR-146a, lncRNA CHRF evoked the activation of NF-κB and JAK1/STAT3 signaling cascades.

gga-miR-451 Negatively Regulates Mycoplasma gallisepticum (HS Strain)-Induced Inflammatory Cytokine Production via Targeting YWHAZ

Mycoplasma gallisepticum (MG) is the most economically significant mycoplasma pathogen of poultry that causes chronic respiratory disease (CRD) in chickens. Although miRNAs have been identified as a major regulator effect on inflammatory response, it is largely unclear how they regulate MG-induced inflammation. The aim of this study was to investigate the functional roles of gga-miR-451 and identify downstream targets regulated by gga-miR-451 in MG infection of chicken. We found that the expression of gga-miR-451 was significantly up-regulated during MG infection of chicken embryo fibroblast cells (DF-1) and chicken embryonic lungs. Overexpression of gga-miR-451 decreased the MG-induced inflammatory cytokine production, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), whereas inhibition of gga-miR-451 had the opposite effect. Gene expression data combined with luciferase reporter assays demonstrated that tyrosine3-monooxygenase/tryptophan5-monooxygenase activation protein zeta (YWHAZ) was identified as a direct target of gga-miR-451 in the context of MG infection. Furthermore, upregulation of gga-miR-451 significantly inhibited the MG-infected DF-1 cells proliferation, induced cell-cycle arrest, and promoted apoptosis. Collectively, our results demonstrate that gga-miR-451 negatively regulates the MG-induced production of inflammatory cytokines via targeting YWHAZ, inhibits the cell cycle progression and cell proliferation, and promotes cell apoptosis. This study provides a better understanding of the molecular mechanisms of MG infection.

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

BACKGROUND

MicroRNAs (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.

METHODS

The 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.

RESULTS

Significantly 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.

CONCLUSIONS

Collectively, 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.

Involvement of microRNA-146a in diabetic peripheral neuropathy through the regulation of inflammation

Purpose

Recent evidence has shown the involvement of inflammation in the development of diabetic peripheral neuropathy (DPN). MicroRNA-146a (miR-146a) is closely involved in the inflammatory response. However, the role of miR-146a in the inflammatory reaction in DPN has not been clarified. This study was designed to explore the role of miR-146a in the regulation of inflammatory responses in DPN.

Methods

Rats were randomly divided into three groups (n=6 per group): control group, type 2 diabetes mellitus (T2DM) group and DPN group. T2DM and DPN rats were intraperitoneally injected with streptozotocin. Sciatic nerve conduction velocity (NCV) was determined at the 6th week and the 12th week in each group. The expression of microRNAs was detected by quantitative real-time polymerase chain reaction in three sciatic nerves for each group of rats. Expression of inflammatory cytokines in nerve tissues and plasma was measured by Western blot and Bio-Plex Pro™ assays.

Results

The NCV and expression levels of miR-146a in the DPN group were significantly decreased (P<0.01) compared to the other two groups. Expression of tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in the DPN group was significantly increased compared with the control and T2DM groups (P<0.01). Pearson’s correlation analysis showed that the expression level of miR-146a was negatively correlated with the levels of IL-1β, TNF-α and NF-κB.

Conclusion

miR-146a is involved in the pathogenesis of DPN, and its expression level is closely related to the inflammatory responses that aggravate sciatic nerve injuries.