Tomato saponin supplementation ameliorates the development of experimental arthritis by regulating inflammatory responses

Abstract

We evaluated the effect of tomato saponin, containing esculeoside A, a major saponin found in Japanese pink-colored tomato, on collagen-induced arthritis DBA/1J mice. Arthritis scores in collagen-injected mice were markedly lower by tomato saponin supplementation than that of the control throughout the 15-days observation period. Notably, there was a significant negative correlation between the arthritis scores and serum concentrations of esculeogenin A, an aglycon of esculeoside A (R2 = 0.84, p < 0.05). Additionally, mRNA expression of pro-inflammatory cytokines in the knee joint were significantly decreased by tomato saponin. Moreover, CD38+CD45R+ splenocytes were significantly increased by tomato saponin, suggesting the shift to the type II helper T cell (Th2) response. In cultured splenocytes from DBA/1J mice, purified esculeogenin A also significantly suppressed the lipopolysaccharide-induced IL-12p40, Th1-driving component, and pro-inflammatory cytokines. Our results suggest that esculeogenin A potentially ameliorates collagen-induced arthritis by inhibiting the pro-inflammatory cytokines involved in the activation of Th1.

Keywords

• Collagen-induced arthritis
• Esculeogenin A
• Inflammatory cytokines
• Tomato saponin