Polyphyllin I Inhibits Propionibacterium acnes-Induced Inflammation In Vitro

Propionibacterium acnes (P. acnes) has been implicated in the progression of acne inflammation. Because current acne medications have various side effects, it is necessary to explore alternative medications possessing anti-inflammatory activity against P. acnes. We investigated the inhibitory effects of polyphyllin I (PPI) on P. acnes-induced inflammation in vitro. In this study, we examined the effects of PPI on the production of inflammatory cytokines in HaCaT keratinocytes treated with heat-killed P. acnes. These treated HaCaT keratinocytes showed increased expression of Toll-like receptor 2 (TLR2) and production of inflammatory cytokines. PPI significantly suppressed the secretion of inflammatory cytokines, including interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α, and the expression of TLR2 in P. acnes-treated cells. Moreover, we studied the influence of PPI on the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways in P. acnes-treated keratinocytes. PPI diminished the activation of NF-κB. Phosphorylated p38 levels were markedly increased after treatment with heat-killed P. acnes but were decreased after treatment with PPI, while the effect of PPI on ERK phosphorylation was not significant. Heat-killed P. acnes and PPI did not have any effect on JNK phosphorylation. Furthermore, we confirmed that NF-κB p65 inhibitor (BAY11-7082), p38 MAPK inhibitor (SB203580), and PPI blocked the expression of IL-8 in heat-killed P. acnes-treated cells. These results demonstrated that PPI has potential for development as a treatment for acne inflammation.