Intervening up-regulated SLC7A5 could mitigate inflammatory mediator by mTOR-P70S6K signal in rheumatoid arthritis synoviocytes.

Objective: The disruption of metabolic events and changes to nutrient and oxygen availability due to sustained inflammation in RA increases the demand of bioenergetic and biosynthetic processes within the damaged tissue. The current study aimed to understand the molecular mechanisms of SLC7A5 (amino acid transporter) in synoviocytes of RA patients.Methods: Synovial tissues were obtained from OA and RA patients. Fibroblast-like synoviocytes (FLS) were isolated and SLC7A5 expression was examined by using RT-qPCR, immunofluorescence and Western blotting. RNAi and antibody blocking treatments were used to knockdown SLC7A5 expression or to block its transporter activities. mTOR activity assay and MMPs expression levels were monitored in RA FLS under amino acid deprivation or nutrient rich conditions. Results: RA FLS displayed significantly upregulated expression of SLC7A5 compared to OA FLS. Cytokine IL-1β was found to play a crucial role in up-regulating SLC7A5 expression via NF-κB pathway. Intervening SLC7A5 expression with RNAi or blocking its function by monoclonal antibody ameliorated MMP3 and MMP13 protein expression. Conversely, up regulation of SLC7A5 or tryptophan supplementation enhanced mTOR-P70S6K signals which promoted the protein translation of MMP3 and MMP13 in RA FLS.Conclusion: Activated NF-κB pathway up-regulates SLC7A5, which enhances mTOR-P70S6K activity and MMP3 and MMP13 expression in RA FLS.

Intervening the up-regulated SLC7A5 could mitigate the inflammatory mediator by mTOR-P70S6K signal in rheumatoid arthritis synoviocytes.

Objective The increased bioenergetic and biosynthetic demands of sustained inflammation and changes to nutrient and oxygen availability are found in rheumatoid arthritis (RA). This study aimed to observe the effects of SLC7A5 (amino acid transporter) on synoviocytes of RA patients and pinpoint the underlying molecular mechanisms. Methods Synovial tissues were collected from OA and RA patients. Fibroblast-like synoviocytes (FLS) were isolated from synovial tissues from RA patients. SLC7A5 expression was evaluated by using RT-qPCR, immunofluorescence and Western blotting. Matrix metalloproteinases (MMPs) expression was evaluated by using RT-qPCR and Western blotting. RNAi and antibody blocking treatments were used to knockdown the expression of SLC7A5 or block its transporting function. Results The SLC7A5 expression was significantly upregulated in the FLS from RA patients compared with that in FLS from OA patients. Cytokine IL-1β played a crucial role in up-regulating SLC7A5 expression via NF-κB pathway in FLS. Intervening SLC7A5 expression with RNAi or blocking SLC7A5 function by monoclonal antibody could ameliorate the MMP3 and MMP13 protein expression. Furthermore, up regulation of SLC7A5 enhanced mTOR-P70SK6 signaling activation which could promote the protein translation of MMP3 and MMP13 in RA FLS. Conclusion SLC7A5 up-regulation could be induced by activated NF-κB pathway, further resulted in an enhanced mTOR-P70S6K activity and the protein expression of MMP3 and MMP13 in FLS from RA patients.

Lipid Peroxidation-Mediated Inflammation Promotes Cell Apoptosis through Activation of NF-κB Pathway in Rheumatoid Arthritis Synovial Cells

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of multiple joints. The central pathogenesis of RA is the proliferation of synovial fibroblasts in response to inflammatory cytokines. However, some of the targeted therapies for inflammation reactions do not display significant clinical improvement after initiation of therapy. Thus, the relationship between inflammatory responses and RA therapy is still incompletely understood. In the present study, we proposed to determine whether enhanced inflammations may lead to cell apoptosis in rheumatoid arthritis synoviocytes. Our results indicated that products of lipid peroxidations, 4-HNE, may induce synovial intrinsic inflammations by activating NF-κB pathways and it may lead to cell apoptosis. Pharmacological inhibition of NF-κB activation may reduce the 4-HNE mediated inflammation responses and subsequent cell apoptosis. Our results may help to clarify the role of inflammations on RA development and imply that blocking NF-κB activation may be partly beneficial for human RA therapy. These findings might provide a mechanism-based rationale for developing new strategy to RA clinical therapy.