PARP1-cGAS-NF-κB pathway of proinflammatory macrophage activation by extracellular vesicles released during Trypanosoma cruzi infection and Chagas disease.

Subhadip Choudhuri,Nisha Jain Garg,David Sacks

doi:10.1371/journal.ppat.1008474

Subhadip Choudhuri, Nisha Jain Garg + Show 1 more

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https://doi.org/10.1371/journal.ppat.1008474

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Abstract

Trypanosoma cruzi (T. cruzi) is the etiological agent of Chagas cardiomyopathy. In the present study, we investigated the role of extracellular vesicles (Ev) in shaping the macrophage (Mφ) response in progressive Chagas disease (CD). We purified T. cruzi Ev (TcEv) from axenic parasite cultures, and T. cruzi-induced Ev (TEv) from the supernatants of infected cells and plasma of acutely and chronically infected wild-type and Parp1-/- mice. Cultured (Raw 264.7) and bone-marrow Mφ responded to TcEV and TEv with a profound increase in the expression and release of TNF-α, IL-6, and IL-1β cytokines. TEv produced by both immune (Mφ) and non-immune (muscle) cells were proinflammatory. Chemical inhibition or genetic deletion of PARP1 (a DNA repair enzyme) significantly depressed the TEv-induced transcriptional and translational activation of proinflammatory Mφ response. Oxidized DNA encapsulated by TEv was necessary for PARP1-dependent proinflammatory Mφ response. Inhibition studies suggested that DNA-sensing innate immune receptors (cGAS>>TLR9) synergized with PARP1 in signaling the NFκB activation, and inhibition of PARP1 and cGAS resulted in >80% inhibition of TEv-induced NFκB activity. Histochemical studies showed intense inflammatory infiltrate associated with profound increase in CD11b+CD68+TNF-α+ Mφ in the myocardium of CD wild-type mice. In comparison, chronically infected Parp1-/- mice exhibited low-to-moderate tissue inflammation, >80% decline in myocardial infiltration of TNF-α+ Mφ, and no change in immunoregulatory IL-10+ Mφ. We conclude that oxidized DNA released with TEv signal the PARP1-cGAS-NF-κB pathway of proinflammatory Mφ activation and worsens the chronic inflammatory pathology in CD. Small molecule antagonists of PARP1-cGAS signaling pathway would potentially be useful in reprogramming the Mφ activation and controlling the chronic inflammation in CD.

Highlights

Chagas disease (CD) is an inflammatory, dilated cardiomyopathy caused by flagellated protozoa Trypanosoma cruzi (T. cruzi)
We show that extracellular vesicles (Ev) released by T. cruzi, T. cruzi-infected cells and in plasma of Chagas mice carry parasite and host DNA that is oxidized
We propose that chemical inhibitors of Poly(ADP-ribose) polymerase 1 (PARP1) offer a potential therapeutic target in arresting chronic inflammation in Chagas disease through modulation of the macrophage proinflammatory signaling

Summary

Introduction

Chagas disease (CD) is an inflammatory, dilated cardiomyopathy caused by flagellated protozoa Trypanosoma cruzi (T. cruzi). Several years later, ~30% of the infected patients progress into clinically symptomatic, chronic CD when they display cardiac insufficiency due to tissue fibrosis, ventricular dilation, and arrhythmia. Macrophages (Mφ) are the innate immune cells that play a critical role in modulating the host response to T. cruzi infection [3]. Activated Mφ, differentiated through the IL12/IFN-γ axis, play a critical role in control of T. cruzi infection [4]. A significant presence of Mφ is noted during the progression of chronic Chagas disease. Stimulus for Mφ proliferation and activation and the role these cells may play in chronic CD is not fully understood [2, 6]

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