Treg responses are associated with PM_2.5-induced exacerbation of viral myocarditis

Abstract

The adverse cardiovascular events induced by ambient fine particles (PM_2.5) are paid more attention in the world. The current study was conducted to explore the mechanisms of T regulatory cells (Treg) responses in PM_2.5-induced exacerbation of viral myocarditis. The male BALB/c mice were administered an intratracheal (i.t.) instillation of 10 mg/kg b.w. PM_2.5 suspension. Twenty-four hours later, the mice were injected intraperitoneally (i.p.) with 100 μl of coxsackievirus B3 (CVB3) diluted in Eagle's minimal essential medium (EMEM). Seven days after the treatment, serum, splenetic, and cardiac tissues were examined. The results showed that pre-exposure to PM_2.5 aggravated the cardiac inflammation in the CVB3-infected mice along with an increase of Treg cells in the spleen. The mRNA expressions of interleukin-6 (IL-6), TNF-α, transforming growth factor-β (TGF-β), and Foxp3 were up-regulated in the PM_2.5-pretreated mice than that in the CVB3-treated mice. Similar results were found in the sera. In addition, compared with the CVB3-treated mice, the cardiac protein expression of TGF-β increased in the PM_2.5-pretreated mice. These results demonstrated that preexposure to PM_2.5 exacerbated virus-induced myocarditis possibly through the depression of the immune response and increase of inflammation in myocardium through the Treg responses.

• Inflammation
• PM_2.5
• treg cell
• viral myocarditis

Declaration of interest

The authors report that they have no conflicts of interests. This work was supported by grants from the National Natural Science Foundation of China (Nos. 81001229 and 81172617).