Abstract
Cucurbitacin B (CuB) is a triterpenoid that is widely distributed in the plant kingdom and has a variety of biological activities. However, the immunomodulatory and anti-inflammatory effects of CuB have not been well characterized. Therefore, in this study, we investigated the effects of CuB on parameters related to antigen presentation and T-cell activation. Specifically, we examined the effects of CuB on basal and lipopolysaccharide (LPS)-induced expression of class I and II MHC molecules, CD40, CD54, CD80, and CD86 in peritoneal macrophages. The LPS-a expression of MHC II, CD40, CD54, and CD80 was significantly attenuated by CuB. However, expression levels of MHC I and CD86 were not changed by CuB. CuB inhibited the production of intracellular reactive oxygen species induced by LPS and blocked the LPS-activated release of pro-inflammatory mediators, such as nitric oxide (NO), prostaglandin E2, tumor necrosis factor-α, interleukin (IL)-6, IL-12, and IL-1β, without any cytotoxicity. Consistent with this, CuB also reduced the expression levels of inducible NO synthase and cyclooxygenase-2 induced by LPS. Furthermore, we demonstrated that the anti-inflammatory effects of CuB were dependent on the induction of heme oxygenase-1 expression via Nrf2 activation. Taken together, these data indicate that CuB possesses immunomodulatory and anti-inflammatory effects, and it may be used as an effective herbal remedy for the treatment and prevention of inflammation.
Declaration of interest
The authors report that they have no conflict of interests. This study was also financially supported by the 2012 Post-DOC. Development Program of Pusan National University. This research was financially supported by the ministry of Trade, Industry and Energy (MOTIE) and Korea Institute for Advancement of Technology (KIAT) through the Promoting Regional specialized Industry (R0002986).