Role of SOCS2 in Modulating Heart Damage and Function in a Murine Model of Acute Chagas Disease

Infection with Trypanosoma cruzi induces inflammation, which limits parasite proliferation but may result in chagasic heart disease. Suppressor of cytokine signaling 2 (SOCS2) is a regulator of immune responses and may therefore participate in the pathogenesis of T. cruzi infection. SOCS2 is expressed during T. cruzi infection, and its expression is partially reduced in infected 5-lipoxygenase-deficient [knock-out (KO)] mice. In SOCS2 KO mice, there was a reduction in both parasitemia and the expression of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), IL-6, IL-10, SOCS1, and SOCS3 in the spleen. Expression of IFN-gamma, TNF-alpha, SOCS1, and SOCS3 was also reduced in the hearts of infected SOCS2 KO mice. There was an increase in the generation and expansion of T regulatory (Treg) cells and a decrease in the number of memory cells in T. cruzi-infected SOCS2 KO mice. Levels of lipoxinA(4) (LXA(4)) increased in these mice. Echocardiography studies demonstrated an impairment of cardiac function in T. cruzi-infected SOCS2 KO mice. There were also changes in calcium handling and in action potential waveforms, and reduced outward potassium currents in isolated cardiac myocytes. Our data suggest that reductions of inflammation and parasitemia in infected SOCS2-deficient mice may be secondary to the increases in Treg cells and LXA(4) levels. This occurs at the cost of greater infection-associated heart dysfunction, highlighting the relevance of balanced inflammatory and immune responses in preventing severe T. cruzi-induced disease. (Am J Pathol 2012, 181:130-140; http://dx.doi.org/10.1016/j.ajpath.2012.03.042)