Ginsenoside Rh2-B1 stimulates cell proliferation and IFN-γ production by activating the p38 MAPK and ERK-dependent signaling pathways in CTLL-2 cells.

CONTEXT: Ginsenoside Rh2, an active component of ginseng, exhibits immunoregulatory and anti-inflammatory properties. Rh2-B1, a sulfated derivative, was prepared to enhance its water solubility. We studied the effect of Rh2-B1 on CTLL-2, a CD8⁺ cytotoxic T cell line that was known for protecting against viral infection. OBJECTIVE: We aimed to investigate the effect of Rh2-B1 on interferon (IFN)-γ production and cell proliferation and its possible mechanism. MATERIALS AND METHODS: Enzyme-linked immunosorbent assay (ELISA) was employed to analyze the IFN-γ concentration of the whole blood and the supernatant of CTLL-2 cell culture. Cell proliferation assay was conducted using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Western blots were used to evaluate changes in signal transduction pathways in CTLL-2 cells. RESULTS: Rh2-B1 was able to enhance IFN-γ production from whole blood culture of Balb/c mice. We then evaluated the effect of Rh2-B1 on a cytotoxic T cell line, CTLL-2 for cell proliferation, IFN-γ production and its molecular mechanism. Rh2-B1 promoted cell proliferation and IFN-γ production of CTLL-2 cells. It also induced activation of p38 mitogen-activated protein kinase (MAPK) and extracellular-signal-regulated kinases (ERK), but inhibited p56 Lck and transducer and activator of transcription 5 (STAT5) expression. The effect was blocked by the specific p38 MAPK inhibitor SB203580 and ERK inhibitor U0126. CONCLUSION: Rh2-B1 could stimulate cell proliferation and IFN-γ production by activating the p38 MAPK- and ERK-dependent signaling pathways in cytotoxic T cells. This may be a novel medicine for treatment of viral infections.

Peimine impairs pro-inflammatory cytokine secretion through the inhibition of the activation of NF-κB and MAPK in LPS-induced RAW264.7 macrophages.

In the previous study, we found that peimine has good anti-inflammatory effects in vivo. However, the anti-inflammatory mechanism of peimine remains unclear. We, therefore, assessed the effects of peimine on inflammatory cytokines in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that peimine (0-25 mg/L) significantly inhibited tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1ß, and increased IL-10 production. Furthermore, peimine significantly inhibited the phosphorylation of p38, ERK and c-jun N-terminal kinase (JNK) as well as decreased p65 and IκB. The present results indicate that peimine inhibits the production of inflammatory cytokines induced by LPS through blocking MAPKs and NF-κB signaling pathways.

Inhibitory effects of sulfated 20(S)-ginsenoside Rh2 on the release of pro-inflammatory mediators in LPS-induced RAW 264.7 cells.

Ginsenoside Rh2 is one of the most important ginsenosides in ginseng with anti-inflammatory and antitumor effects. However, the extremely poor oral bioavailability induced by its low water solubility greatly limits the potency of Rh2 in vivo. In the previous study, we sulfated 20(S)-ginsenoside Rh2 with chlorosulfonic acid and pyridine method, and got one novel derivative, Rh2-B1, with higher water solubility and greater immunologic enhancement than Rh2. However, the anti-inflammatory effect of Rh2-B1 remains unclear. We therefore investigated the effects of Rh2-B1 on lipopolysaccharide (LPS)-induced proinflammatory mediators in RAW 264.7 macrophages. We found that Rh2-B1 dramatically inhibited LPS-induced overproduction of nitric oxide, prostaglandin E2, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6. Consistently, the protein and mRNA expression levels of inducible nitric oxide synthase and cyclooxygenase-2 were remarkably decreased by Rh2-B1. In addition, Rh2-B1 significantly suppressed the phosphorylations of p38, c-Jun N-terminal kinase, and extracellular signal receptor-activated kinase 1/2 induced by LPS. Rh2-B1 was further shown to inhibit NF-κB p65 translocation into the nucleus by suppressing IκBα degradation. In conclusion, we demonstrate that Rh2-B1 inhibits the release of LPS-induced pro-inflammatory mediators through blocking mitogen-activated protein kinases and NF-κB signaling pathways, suggesting that sulfated ginsenosides could be potential agents for anti-inflammatory therapies.