Curcumin attenuates ovalbumin-induced asthma via regulating Th9 cell production
Abstract: Curcumin is a polyphenol compound with anti-inflammatory effect. It can reduce the oxidative stress response of asthmatic patients by inhibiting the production of NO, thus alleviating the occurrence of airway inflammation. In this study, we further studied the molecular mechanism of curcumin in ovalbumin (OVA)-sensitized mice. Compared with OVA group, injection of curcumin reduced the number of inflammatory cells in bronchoalveolar lavage fluid (BALF) and attenuated airway sensitivity in mice. ELISA tests showed that curcumin reduced levels of tumor growth factor (TGF)-β, interleukin (IL)-4, IL-9, and IL-10 in BALF; IL-9 and IL-10 were also reduced in lung tissues. Western blot showed that curcumin inhibited collagen deposition and α-smooth muscle actin (α-SMA) secretion in lung tissues; meanwhile TGF-β and phosphorylated Smad3 was down-regulated. Flow cytometry analysis showed that the proportion of T helper (Th) 9 cells in peripheral blood mononuclearcells decreased after curcumin injection. These results suggested that curcumin could attenuate OVA-induced asthma in mice via regulating Th9 differentiation. Inhibition of TGF-β/Smad signaling pathway was probably involved.