interleukin-8 and Hyperuricemia

Acute inflammation and hyperuricemia are associated with gouty arthritis. As an edible and therapeutic mushroom,

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Arthritis, Gouty; Edema; Hyperuricemia; Interleukin-8; Ligands; Matrix Metalloproteinase 9; Mice; Rats; Rodentia; Tumor Necrosis Factor-alpha; Uric Acid; Xanthine Oxidase

Hyperuricemia is an important risk factor for atherosclerosis, yet the potential mechanisms are not well understood. Migration and adhesion of leukocytes to endothelial cells play key roles in initiation and development of atherosclerosis. We investigated monocyte-endothelial cell interactions and potential signaling pathways under uric acid (UA)-stimulated conditions.. Primary human umbilical vein endothelial cells (HUVECs) were cultured and exposed to different concentrations of UA for various periods. Experimental hyperuricemia rat models were established. Expression of chemoattractant protein-1 (MCP-1), interleukin 8 (IL-8), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) were evaluated. Monocyte-endothelial cell interactions were elucidated by chemotaxis and adhesion assays, and nuclear factor-kappa B (NF-κB) pathway was studied using fluorescent microscopy and electrophoretic mobility shift assay. Results showed that high concentration of UA stimulated generation of chemokines and adhesion molecules in ex vivo and in vivo experiments. Migration and adhesion of human monocytic leukemia cell line THP-1 cells to HUVECs were promoted and activated NF-κB was significantly increased. UA-induced responses were ameliorated by organic anion transporter inhibitor probenecid and NF-κB inhibitor BAY11-7082. It was also observed that human endothelial cells expressed urate transporter-1, which was not regulated by UA.. High concentration of UA exerts unfavorable effects directly on vascular endothelium via the NF-κB signaling pathway, the process of which requires intracellular uptake of UA.

Topics: Animals; Atherosclerosis; Cell Adhesion; Cell Adhesion Molecules; Cell Survival; Chemokine CCL2; Chemokines; Disease Models, Animal; Endothelial Cells; Endothelium, Vascular; Gene Expression Regulation; Human Umbilical Vein Endothelial Cells; Humans; Hyperuricemia; Intercellular Adhesion Molecule-1; Interleukin-8; Male; Monocytes; NF-kappa B; Nitriles; Organic Anion Transporters; Organic Cation Transport Proteins; Rats; Rats, Wistar; Signal Transduction; Sulfones; Uric Acid; Vascular Cell Adhesion Molecule-1

MicroRNAs (miRNA) are small non-coding RNAs that function as post-transcriptional repressors of gene expression. We hypothesised that miRNA regulate gene expression of proinflammatory cytokines in response to monosodium urate (MSU) crystals.. We stimulated human monocytic THP-1 cells with MSU crystals and examined miRNA and proinflammatory cytokine gene expression. The effects of miR-146a overexpression were examined by transfecting THP-1 cells with miR-146a precursor. miR-146a expression was examined in the urate peritonitis model, in peripheral blood mononuclear cells from people with gout and control participants, and in gouty tophus samples.. MSU crystals increased miR-146a expression in THP-1 cells, but not other miRNA implicated in interleukin (IL)-1β regulation. Overexpression of miR-146a expression reduced MSU crystal-induced IL-1β, tumour necrosis factor-α (TNFα), monocyte chemoattractant protein-1 (MCP-1) and IL-8 gene expression. In the urate peritonitis model, reduced miR-146a expression was observed during the acute inflammatory response to MSU crystal injection. In people with intercritical gout, peripheral blood mononuclear cells expressed significantly higher levels of miR-146a, compared with normouricaemic and hyperuricaemic control participants and those with acute gout flares. Expression of miR-146a was also observed in all tophus samples.. Collectively, these data suggest that miR-146a is a transcriptional brake that is lost during the acute inflammatory response to MSU crystals.

Topics: Animals; Antioxidants; Case-Control Studies; Cell Line; Disease Models, Animal; Female; Gene Expression; Gout; Humans; Hyperuricemia; Interleukin-1beta; Interleukin-8; Male; Mice; MicroRNAs; Monocytes; Tumor Necrosis Factor-alpha; Uric Acid

Hyperuricemia-mediated uric acid crystal formation may cause joint inflammation and provoke the destruction of joints through the activation of inflammasome-mediated innate immune responses. However, the immunopathological effects and underlying intracellular regulatory mechanisms of uric acid crystal-mediated activation of fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA) have not been elucidated. Therefore, we investigated the in vitro effects of monosodium urate crystals, alone or in combination with the inflammatory cytokines tumor-necrosis factor (TNF)-α or interleukin (IL)-1β, on the activation of human FLS from RA patients and normal control subjects and the underlying intracellular signaling mechanisms of treatment with these crystals. Monosodium urate crystals were able to significantly increase the release of the inflammatory cytokine IL-6, the chemokine CXCL8 and the matrix metalloproteinase (MMP)-1 from both normal and RA-FLS (all P<0.05). Moreover, the additive or synergistic effect on the release of IL-6, CXCL8 and MMP-1 from both normal and RA-FLS was observed following the combined treatment with monosodium urate crystals and TNF-α or IL-1β. Further experiments showed that the release of the measured inflammatory cytokine, chemokine and MMP-1 stimulated by monosodium urate crystals were differentially regulated by the intracellular activation of extracellular signal-regulated kinase and c-Jun N-terminal kinase pathways but not the p38 mitogen-activated protein kinase pathway. Our results therefore provide a new insight into the uric acid crystal-activated immunopathological mechanisms mediated by distinct intracellular signal transduction pathways leading to joint inflammation in RA.

Topics: Arthritis, Rheumatoid; Cells, Cultured; Drug Synergism; Enzyme Activation; Enzyme-Linked Immunosorbent Assay; Extracellular Signal-Regulated MAP Kinases; Fibroblasts; Humans; Hyperuricemia; Inflammation; Interleukin-1beta; Interleukin-6; Interleukin-8; JNK Mitogen-Activated Protein Kinases; Matrix Metalloproteinase 1; Signal Transduction; Synovial Fluid; Tumor Necrosis Factor-alpha; Uric Acid