Puerarin alleviates delayed-type hypersensitivity via cytokine inhibition by modulating Th1/Th2 balance

Puerarin has long been used as a traditional Chinese medicine, which possesses various physiological properties, including anti-inflammation, anti-oxidative, anti-diabetic and anti-cancer activities. The aim of the current study was to investigate the effect of puerarin on delayed-type hypersensitivity (DTH) induced by ovalbumin (OVA) in mice and explore its underlying mechanisms. The results showed that puerarin significantly attenuated DTH, resulting from a decrement in footpad swelling, reduction in inflammatory cell as well as a decline in anti-OVA IgG in serum. In the homogenized supernatant of footpad tissues, the classic Th1-cytokines, including interferon (IFN)-γ was suppressed following puerarin treatment. Furthermore, a high dose of puerarin inhibited interleukin (IL)-4 production, the classic Th2-cytokine. The concanavalin A stimulation and MTT assays indicated a suppressive effect of puerarin on Th1 response via decreasing IFN-γ production in OVA-primed lymphocytes. Detailed studies revealed that puerarin modulated the Th1/Th2 balance in DTH responses, attributing to lower T-bet/GATA binding protein-3 mRNA and protein level ratios, which led to the shift change of IFN-γ/IL-4 with puerarin treatment. These findings demonstrate that puerarin alleviated inflammation in DTH triggered by OVA application via curbing inflammatory cytokines by modulating the Th1/Th2 balance. These results suggest that puerarin may be an alternative therapeutic option for the treatment of DTH.