4-Octyl Itaconate Alleviates Experimental Autoimmune Myocarditis Through Reducing M1-Like Macrophage

Background: Myocarditis is one of the important causes of acute and chronic heart failure.There is currently no specific treatment plan.Fulminant and severe myocarditis,which progresses rapidly and has a high mortality rate.The function and number of macrophages are closely related to the degree of Myocarditis.Acod-1/Itaconate as an intracellular metabolite can negatively regulate the function of macrophages,but its role is unclear in myocarditis.Methods: 6-8W male Balb/c mice were used to construct an experimental autoimmune myocarditis model(EAM).Mice were randomly divided into three groups: Sham group(subcutaneous injection of normal saline + intraperitoneal injection of normal saline),EAM group(subcutaneous injection of My HC-α/CFA mixture + intraperitoneal injection of normal saline),and OI group(subcutaneous My HC-α/CFA mixture + intraperitoneal injection of OI,100mg/kg·d).We recorded mouse body weight changes on day 0,day 7,day 14 and day 21,and collected serum and heart specimens on day 21.The degree of inflammation and fibrosis in mouse heart tissues was assessed by HE& Masson staining.The expression levels of inflammatory factors(TNF-α,IL-6 and IL-1β)were detected by PCR and WB.Immunofluorescence and immunohistochemistry were used to study immune cell infiltration and differentiation of macrophages.in vitro experiments,RAW264.7 were stimulated by LPS/INF-γ,and then were analyzed by flow cytometry(F4/80,CD86),q RT-PCR(i NOS,CD86)and western blot.Results: There are a large number of M1 infiltrated in myocarditis.In vivo,OI can reduce the heart weight/body weight ratio,reduce the levels of inflammatory factors(TNF-α,IL-6 and IL-1β)),and reduce M1 infiltration.In vitro experiments,OI reduced the inflammatory response of macrophages induced by LPS and inhibited macrophage polarization.In addition,Our research shows that OI reduces the inflammatory response of macrophages dependent on hypoxia-inducible factor 1-α.Conclusion: Based on the above results,we found that Acod-1/Itaconate is involved in the progression of autoimmune myocarditis.Exogenous Itaconate(OI)can inhibit the inflammatory response of macrophages in myocarditis tissue by regulating HIF-1α.It may be a new way to treat myocarditis.