microRNA-223 Deficiency Exacerbates Acute Inflammatory Response to Monosodium Urate Crystals by Targeting NLRP3.

OBJECTIVE: MicroRNAs were identified as master-switch molecules limiting acute inflammatory response. This study investigated the potential role of microRNA (miR)-223 in the mechanism of gout. METHODS: Wild-type (WT) and miR-223 knock-out (KO) mice were used to evaluate the phenotypes of gout models. Inflammatory cytokines were measured in air pouch and peritoneal cavity lavage fluid. In addition to miR-223 level in gout patients, miR-223 and pro-inflammatory genes were examined in bone marrow-derived macrophages (BMDMs) from mice as well as peripheral blood mononuclear cells from healthy controls (HC) treated with monosodium urate (MSU) crystals in vitro. RESULTS: MiR-223 was up-regulated in the early phase in BMDMs from WT mice after MSU challenge and decreased rapidly, and this was not observed in miR-223 KO mice in vitro. In addition, miR-223 was required for macrophages homeostasis. In comparison with WT mice in vivo, miR-223 deficiency exacerbated swelling index of MSU-induced inflammation in foot pad and ankle joint models. MiR-223 deficiency also markedly aggravated inflammatory cells infiltration and cytokines release including interleukin (IL)-1ß, IL-6 and monocyte chemotactic protein-1 (MCP-1) in the air pouch and peritonitis models. In the in vitro experiments, miR-223 deficiency promoted the inflammatory response by targeting NLR family pyrin domain containing protein 3 (NLRP3). Besides, miR-223 level was down-regulated in gout patients and in HC exposed to MSU in vitro. CONCLUSION: MiR-223 was down-regulated in gout patients and miR-223 deficiency exacerbated inflammatory response in diverse murine models, suggesting that up-regulation of miR-223 could be a potential therapeutic strategy for alleviating gouty inflammation.

Downregulation of Transcription Factor T-Bet as a Protective Strategy in Monosodium Urate-Induced Gouty Inflammation.

Gout is sterile joint inflammation triggered by the damaging effects of monosodium urate (MSU) crystals accumulation. Previous studies suggest transcription factor T-bet plays an important role in inflammatory arthritis. Notably, mice lacking T-bet markedly reduced joint inflammation of rheumatoid arthritis models, however, the involvement of T-bet in gouty inflammation has yet to be clarified. Here, we took advantage of T-bet knockout (KO) mice to investigate the role of T-bet in the pathogenesis of MSU-induced gout inflammation. T-bet KO and wild type (WT) mice were used for models of acute inflammation induced with MSU crystals, including footpad, air pouch and peritonitis models. Inflammatory cytokines and phagocytosis were detected in bone-marrow-derived macrophages (BMDMs) from T-bet KO and WT mice treated with MSU crystals in vitro. In addition, T-bet expression in peripheral blood mononuclear cells (PBMCs) from gout patients was measured, as well as plasma inflammatory cytokines. We found that the levels of interleukin (IL)-17, IL-23, and interferon-γ were reduced, but tumor necrosis factor-α was not, in BMDMs from T-bet KO compared with WT mice after MSU challenge in vitro, as well as MSU phagocytosis. In comparison with WT mice in vivo, the swelling index of T-bet KO mice was significantly decreased in the footpad model. T-bet deficiency also dramatically relieved MSU-induced inflammatory cell infiltration in peritonitis and air pouch models in vivo, and as well as the IL-1ß levels of air pouch lavage fluid (APLF). In addition, plasma IL-17 and IL-23 levels were elevated in acute gout, whereas protein levels of T-bet were downregulated in PBMCs from acute gout patients and intercritical gout treated with MSU crystals in vitro as well. Transcription factor T-bet deficiency protects against MSU-induced gouty inflammation, suggesting that downregulation of T-bet could be a protective strategy and contribute to spontaneous remission of inflammation in acute gout.

Resveratrol ameliorates gouty inflammation via upregulation of sirtuin 1 to promote autophagy in gout patients.

BACKGROUND: Resveratrol exerts an anti-inflammatory effect on collagen-induced arthritis and osteoarthritis in rats via activation of sirtuin 1 (SIRT1). Autophagy can be induced by resveratrol and leads to amelioration of interleukin-1 beta (IL-1ß) release in vitro. We aimed to determine the anti-inflammatory mechanisms of resveratrol in patients with gout. METHODS: Blood samples were obtained from patients with acute gout, intercritical gout (IG) and healthy controls (HC). The mRNA and protein levels of SIRT1 and nuclear factor-kappa B (NF-kB) p65 were determined in peripheral blood mononuclear cells (PBMCs) lysate from these patients. In the in vitro experiment, SIRT1, autophagy-related genes (beclin-1 and microtubule-associated protein 1 light-chain 3) and key genes involved in the gouty inflammatory pathway, including NF-κB p65, NLR family pyrin domain containing 3 (NLRP3), caspase-1 and IL-1ß, were determined in PBMCs lysate or plasma from IG patients exposed to monosodium urate (MSU) crystals with or without resveratrol. RESULTS: The mRNA and protein levels of SIRT1 were downregulated in PBMCs from gout patients in comparison with HC. In the in vitro experiment, the protein levels of SIRT1 were downregulated in PBMCs from IG patients exposed to MSU crystals and were restored by resveratrol in a dose-dependent manner. Furthermore, high doses of resveratrol ameliorated the release of the inflammatory cytokine IL-1ß. In addition, the mRNA levels of NLRP3 and NF-κB p65 were regulated by resveratrol, but caspase-1 and IL-1ß were not. Furthermore, resveratrol promoted MSU-induced autophagy in PBMCs from patients with gout. CONCLUSION: These findings suggest that resveratrol ameliorates gouty inflammation via upregulation of SIRT1 to promote autophagy in patients with gout.

Systemic lupus erythematosus complicated by noncirrhotic portal hypertension: A case report and review of literature.

A 48 year-old Chinese woman suffering from polyarthritis, irregular fever and trichomadesis was admitted to the hospital. A diagnosis of systemic lupus erythematosus (SLE) was made based on polyarthritis, pancytopenia, reduced complement 3, multiple positive autoantibodies, a positive Coomb's test and protein in her urine. In addition, splenomegaly was detected during physical examination and confirmed by abdominal ultrasonography and magnetic resonance imaging, indicating that the patient had SLE and portal hypertension. Further negative investigations ruled out the possibility of cirrhosis. The patient was diagnosed with active SLE complicated by noncirrhotic portal hypertension (NCPH) without liver histopathology, due to the patient's refusal for liver biopsy. Portal vein diameter and splenomegaly decreased following treatment with methylprednisolone, hydroxychloroquine and metoprolol tartrate. To date, SLE complicated by NCPH has rarely been reported, as it is under-recognized clinically as well as pathologically. Here we describe a case of SLE complicated by NCPH and review the literature for its characteristics, which may contribute to improving the recognition of NCPH and reducing missed and delayed diagnosis of this disorder.

Association of NLRP3 polymorphisms with susceptibility to primary gouty arthritis in a Chinese Han population.

The NLRP3-interleukin1ß (IL1ß) signaling pathway is involved in monosodium urate (MSU)-mediated inflammation. The aim of this present study was to determine whether single nucleotide polymorphisms (SNPs) in the NLRP3 gene are associated with susceptibility to gouty arthritis (GA) and whether these SNPs alter the expression of components of the NLRP3-IL1ß signaling pathway. The rs10754558, rs4612666, and rs1539019 SNPs were detected in 583 patients with GA and 459 healthy subjects. NLRP3 and IL1ß mRNA levels in peripheral blood mononuclear cells (PBMCs) and serum IL1ß levels were measured in different genotype carriers, and correlations between the NLRP3 SNPs and NLRP3 mRNA, IL1ß mRNA, and serum IL1ß levels were investigated. The GG genotype of NLRP3 rs10754558 was found to be significantly associated with patients with GA compared to the healthy control subjects via multivariate logistic regression analysis (adjusted OR = 2.68, P = 0.006). The CGA haplotypes were independently associated with patients with GA compared to the healthy control subjects (adjusted OR = 1.968, P = 0.02). The levels of NLRP3 mRNA, IL1ß mRNA, and serum IL1ß in the patients with GA were significantly different among the three genotypes of rs10754558 (all P < 0.01). The GG genotype of rs10754558 and the CGA haplotype of rs4612666-C, rs10754558-G, and rs1539019-A are both independent risk factors for primary GA development. The rs10754558 polymorphism might participate in regulating immune and inflammation responses in patients with GA by influencing the expression of components of the NLRP3 inflammasome. Future multicenter studies aimed at replicating these findings in an independent population as well as functional tests will aid in further defining the role of these SNPs in the development of GA.