LL-37 alone and in combination with IL17A enhances proinflammatory cytokine expression in parallel with hyaluronan metabolism in human synovial sarcoma cell line SW982-A step toward understanding the development of inflammatory arthritis.

LL-37 is the only human cathelicidin-family host defense peptide and has been reported to interact with invading pathogens causing inflammation at various body sites. Recent studies showed high levels of LL-37 in the synovial-lining membrane of patients with rheumatoid arthritis, a common type of inflammatory arthritis. The present study aims to investigate the role of LL-37 on mechanisms associated with pathogenesis of inflammatory arthritis. The effects of LL-37 on the expression of proinflammatory cytokines, hyaluronan (HA) metabolism-related genes, cell death-related pathways, and cell invasion were investigated in SW982, a human synovial sarcoma cell line. Time-course measurements of proinflammatory cytokines and mediators showed that LL-37 significantly induced IL6 and IL17A mRNA levels at early time points (3-6 hr). HA-metabolism-related genes (i.e., HA synthase 2 (HAS2), HAS3, hyaluronidase 1 (HYAL1), HYAL2, and CD44) were co-expressed in parallel. In combination, LL-37 and IL17A significantly enhanced PTGS2, TNF, and HAS3 gene expression concomitantly with the elevation of their respective products, PGE2, TNF, and HA. Cell invasion rates and FN1 gene expression were also significantly enhanced. However, LL-37 alone or combined with IL17A did not affect cell mortality or cell cycle. Treatment of SW982 cells with both LL-37 and IL17A significantly enhanced IKK and p65 phosphorylation. These findings suggest that the chronic production of a high level of LL-37 may synchronize with its downstream proinflammatory cytokines, especially IL17A, contributing to the co-operative enhancement of pathogenesis mechanisms of inflammatory arthritis, such as high production of proinflammatory cytokines and mediators together with the activation of HA-metabolism-associated genes and cell invasion.

Ethanolic extract of Kaempferia parviflora interrupts the mechanisms-associated rheumatoid arthritis in SW982 culture model via p38/STAT1 and STAT3 pathways.

BACKGROUND: Kaempferia parviflora Wall. ex Baker (KP) has long been used in traditional medicine to treat various diseases because active compounds in rhizome extracts are important anti-inflammatory agents. PURPOSE: This study aims to investigate the effects of an ethanolic extract of KP on the molecular mechanisms associated with rheumatoid arthritis (RA), which was induced by a combination of proinflammatory cytokines (IL-1ß or TNF-α with IL-17A) in a human synovial sarcoma cell line (SW982) culture model. METHODS: SW982 cells pretreated with cytokines were incubated with KP extract at 3-30 µg/ml, or three major compounds of KP (5,7-dimethoxyflavone, 5,7,4'-trimethoxyflavone, and 3,5,7,3',4'-pentamethoxyflavone) for up to 72 h. Dexamethasone was used as positive control. RA-associated genes and inflammatory products were measured in parallel with cell death genes. Apoptosis by flow cytometry and migration assay were also analyzed. Western blotting was used to examine the effects on intracellular signaling mechanisms. RESULTS: KP extract markedly reduced the expression of genes and levels of proinflammatory cytokines, inflammatory mediators, and matrix-degraded enzymes, but neither induced apoptosis nor altered the cell cycle. Its major constituents differently exerted suppressive effects on inflammatory genes. The KP extract downregulated the expression of genes associated with autophagosome and necroptosome formations. The extract also inhibited cell migration, reduced the mRNA expression of cadherin-11, and selectively reduced the phosphorylation of p38 MAPK, STAT1, and STAT3 signaling molecules, but did not interfere with the NF-κB pathway. CONCLUSION: These results suggest that the anti-arthritic potential of KP extract results from anti-inflammation and anti-migration via the suppression of the cytokines-induced p38/STAT1 and STAT3 pathways.