Yokukansan, a Japanese Herbal Medicine, Suppresses Substance PInduced Production of Interleukin-6 and Interleukin-8 by Human U373 MG Glioblastoma Astrocytoma Cells.

BACKGROUND: Yokukansan is a traditional Japanese herbal medicine that has an antiallodynic effect in patients with chronic pain. However, the mechanisms by which yokukansan inhibits neuropathic pain are unclear. OBJECTIVE: This study aimed to investigate the molecular effects of yokukansan on neuroinflammation in U373 MG glioblastoma astrocytoma cells, which express a functional high-affinity neurokinin 1 receptor (substance P receptor), and produce interleukin (IL)-6 and IL-8 in response to stimulation by substance P (SP). METHODS: We assessed the effect of yokukansan on the expression of ERK1/2, P38 MAPK, nuclear factor (NF)-κB, and cyclooxygenase-2 (COX-2) in U373 cells by western blot assay. Levels of IL-6 and IL-8 in conditioned medium obtained after stimulation of cells with SP for 24 h were measured by enzyme-linked immunosorbent assay. All experiments were conducted in triplicate. Results were analyzed by one-way ANOVA, and significance was accepted at p < 0.05. RESULTS: Yokukansan suppressed SP-induced production of IL-6 and IL-8 by U373 MG cells, and downregulated SP-induced COX-2 expression. Yokukansan also inhibited phosphorylation of ERK1/2 and p38 MAPK, as well as nuclear translocation of NF-κB, induced by SP stimulation of U373 MG cells. CONCLUSION: Yokukansan exhibits anti-inflammatory activity by suppressing SP-induced production of IL-6 and IL-8 and downregulating COX-2 expression in U373 MG cells, possibly via inhibition of the activation of signaling molecules, such as ERK1/2, p38 MAPK, and NF-κB.

Evaluation of the anti-inflammatory actions of various functional food materials including glucosamine on synovial cells.

The anti-inflammatory actions of glucosamine (GlcN) on arthritic disorders involve the suppression of inflammatory mediator production from synovial cells. GlcN has also been reported to inhibit the activation of the p38 mitogen-activated protein kinase (MAPK) pathway. The present study aimed to determine the cooperative and anti­inflammatory actions of functional food materials and evaluated the production of interleukin (IL)­8 and phosphorylation of p38 MAPK in IL-1ß-activated synovial cells, incubated with the combination of GlcN and various functional food materials containing L­methionine (Met), undenatured type II collagen (UC­II), chondroitin sulfate (CS), methylsulfonylmethane (MSM) and agaro-oligosaccharide (AO). The results indicated that Met, UC­II, CS, MSM and AO slightly or moderately suppressed the IL-1ß-stimulated IL­8 production by human synovial MH7A cells. The same compounds further decreased the IL­8 level lowered by GlcN. Similarly, they slightly suppressed the phosphorylation level of p38 MAPK and further reduced the phosphorylation level lowered by GlcN. These observations suggest a possibility that these functional food materials exert an anti­inflammatory action (inhibition of IL­8 production) in combination with GlcN by cooperatively suppressing the p38 MAPK signaling (phosphorylation).

Glucosamine Downregulates the IL-1ß-Induced Expression of Proinflammatory Cytokine Genes in Human Synovial MH7A Cells by O-GlcNAc Modification-Dependent and -Independent Mechanisms.

Osteoarthritis (OA) is one of the major joint diseases, and the synovial inflammation is involved in the pathogenesis and progression of OA. Glucosamine (GlcN) is widely used as a dietary supplement for OA, and is expected to exert the antiinflammatory action in OA. However, the detailed mechanism for the antiinflammatory action of GlcN remains poorly understood. In this study, to elucidate the molecular mechanism involved in the GlcN-medicated regulation of synovial cell activation, we comprehensively analyzed the effect of GlcN on the gene expression using a human synovial cell line MH7A by DNA microarray. The results indicated that GlcN significantly downregulates the expression of 187 genes (≤1/1.5-fold) and upregulates the expression of 194 genes (≥1.5-fold) in IL-1ß-stimulated MH7A cells. Interestingly, pathway analysis indicated that among the 10 pathways into which the GlcN-regulated genes are categorized, the 4 pathways are immune-related. Furthermore, GlcN suppressed the expression of proinflammatory cytokine genes (such as IL-6, IL-8, IL-24 and TNF-α genes). In addition, GlcN-mediated O-GlcNAc modification was involved in the downregulation of TNF-α and IL-8 genes but not IL-6 and IL-24 genes, based on the effects of alloxan, an O-GlcNAc transferase inhibitor. Thus, GlcN likely exerts an antiinflammatroy action in OA by suppressing the expression of proinflammatory cytokine genes in synovial MH7A cells by O-GlcNAc modification-dependent and -independent mechanisms.