Trypanosoma cruzi Induces the PARP1/AP-1 Pathway for Upregulation of Metalloproteinases and Transforming Growth Factor β in Macrophages: Role in Cardiac Fibroblast Differentiation and Fibrosis in Chagas Disease

Chagas disease (CD), caused by Trypanosoma cruzi, is a degenerative heart condition. In the present study, we investigated the role of poly [ADP-ribose] polymerase 1/activator protein 1 (PARP1/AP-1) in upregulation of profibrotic macrophages (Mϕ) and subsequent development of cardiac fibrosis in CD. We used in vitro and in vivo models of T. cruzi infection and chemical and genetic inhibition of Parp1 to examine the molecular mechanisms by which Mϕ might augment profibrotic events in CD. Cultured (RAW 264.7 and THP-1) Mϕ infected with T. cruzi and primary cardiac and splenic Mϕ of chronically infected mice exhibited a significant increase in the expression, activity, and release of metalloproteinases (MMP2, MMP9, and MMP12) and the cytokine transforming growth factor β (TGF-β). Mϕ release of MMPs and TGF-β signaled the cardiac fibroblast to myofibroblast differentiation, as evidenced by a shift from S100A4 to alpha smooth muscle actin (α-SMA) expression. Incubation of infected Mϕ with MMP2 and MMP9 inhibitors resulted in 60 to 74% decline in TGF-β release, and MMP9 and PARP1 inhibitors resulted in 57 to 70% decline in Mϕ TGF-β-driven cardiac fibroblast differentiation. Likewise, histological studies showed a 12- to 16-fold increase in myocardial expression of CD68 (Mϕ marker) and its colocalization with MMP9/TGF-β, galectin-3, and vimentin in wild-type mice with CD. In comparison, chronically infected Parp1(−/−) mice exhibited a >50% decline in myocardial levels of Mϕ and associated fibrosis markers. Further study showed that PARP1 synergized with c-Fos and JunB AP-1 family members for transcriptional activation of profibrotic response after T. cruzi infection. We conclude that PARP1 inhibition offers a potential therapy for controlling the T. cruzi-driven fibroblast differentiation in CD through modulation of the Mϕ signaling of the AP-1–MMP9–TGF-β pathway.