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 (M phi) 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 M phi might augment profibrotic events in CD. Cultured (RAW 264.7 and THP-1) M phi infected with T. cruzi and primary cardiac and splenic M phi 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 beta (TGF-beta). M phi release of MMPs and TGF-beta signaled the cardiac fibroblast to myofibroblast differentiation, as evidenced by a shift from S100A4 to alpha smooth muscle actin (alpha-SMA) expression. Incubation of infected M phi with MMP2 and MMP9 inhibitors resulted in 60 to 74% decline in TGF-beta release, and MMP9 and PARP1 inhibitors resulted in 57 to 70% decline in M phi TGF-beta-driven cardiac fibroblast differentiation. Likewise, histological studies showed a 12- to 16-fold increase in myocardial expression of CD68 (M phi marker) and its colocalization with MMP9/TGF-beta, galectin-3, and vimentin in wildtype mice with CD. In comparison, chronically infected Parp1(-/-) mice exhibited a >50% decline in myocardial levels of M phi 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 M phi signaling of the AP-1MMP9-TGF-beta pathway. IMPORTANCE Cardiomyopathy is the most important clinical manifestation of T. cruzi-driven CD. Recent studies have suggested the detrimental role of the matrix metalloproteinases MMP2 and MMP9 in extracellular matrix (ECM) degradation during cardiac remodeling in T. cruzi infection. Peripheral TGF-beta levels are increased in clinically symptomatic CD patients over those in clinically asymptomatic seropositive individuals. We provide the first evidence that during T. cruzi infection, M phi release of MMP2 and MMP9 plays an active role in activation of TGF-beta signaling of ECM remodeling and cardiac fibroblast-to-myofibroblast differentiation. We also determined that PARP1 signals c-Fos- and JunB-mediated AP-1 transcriptional activation of profibrotic gene expression and demonstrated the significance of PARP1 inhibition in controlling chronic fibrosis in Chagas disease. Our study provides a promising therapeutic approach for controlling T. cruzi-driven fibroblast differentiation in CD by PARP1 inhibitors through modulation of the M phi signaling of the AP-1-MMP9-TGF-beta pathway.