Resveratrol inhibits Toxoplasma gondii-induced lung injury, inflammatory cascade and evidences of its mechanism of action

Abstract

Background: Toxoplasma gondii is an opportunistic protozoan that can infect host to cause toxoplasmosis. We have previously reported that resveratrol (RSV) has protective effects against liver damage in T. gondii infected mice. However, the effect of RSV on lung injury caused by T. gondii infection and its mechanism of action remain unclear.

Purpose: In this work, we studied the protective effects of RSV on lung injury caused by T. gondii infection and explored the underlying mechanism.

Methods: Molecular docking and localized surface plasmon resonance assay were used to detect the molecular interactions between RSV and target proteins. In vitro, the anti-T. gondii effects and potential anti-inflammatory mechanisms of RSV were investigated by quantitative competitive-PCR, RT-PCR, ELISA, Western blotting and immunofluorescence using RAW 264.7 cells infected with tachyzoites of T. gondii RH strain. In vivo, the effects of RSV on lung injury caused by T. gondii infection were assessed by observing pathological changes and the expression of inflammatory factors of lung.

Results: RSV inhibited T. gondii loads and T. gondii-derived heat shock protein 70 (T.g.HSP70) expression in RAW 264.7 cells and lung tissues. Moreover, RSV interacts with T.g.HSP70 and toll-like receptor 4 (TLR4), respectively, and interferes with the interaction between T.g.HSP70 and TLR4. It also inhibited the overproduction of inducible nitric oxide synthase, TNF-α and high mobility group protein 1 (HMGB1) by down-regulating TLR4/nuclear factor kappa B (NF-κB) signaling pathway, which is consistent with the effect of TLR4 inhibitor CLI-095. In vivo, RSV improved the pathological lung damage produced by T. gondii infection, as well as decreased the number of inflammatory cells in bronchoalveolar lavage fluid and the release of HMGB1 and TNF-α.

Conclusion: These findings indicate that RSV can inhibit the proliferation of T. gondii and T.g.HSP70 expression both in vitro and in vivo. RSV can inhibit excessive inflammatory response by intervening T.g.HSP70 and HMGB1 mediated TLR4/NF-κB signaling pathway activation, thereby ameliorating lung injury caused by T. gondii infection. The present study provides new data that may be useful for the development of RSV as a new agent for the treatment of lung damage caused by T. gondii infection.

Keywords: Resveratrol; T. gondii HSP70; TLR4/NF-κB; Toxoplasma gondii; inflammation; lung injury.