Deposição de DNA no fígado como um novo fenômeno da lesão hepática medicamentosa

Abstract

Drug-induced liver injury (DILI) is an important cause of acute liver failure (FHA), but with limited therapeutic options. During DILI, oncotic necrosis with concomitant release and recognition of intracellular content amplifies liver inflammation and injury. Amongst these molecules, DNA has been widely shown to trigger inflammatory and autoimmune diseases; however, the mechanisms involved in DNA release from damaged hepatocytes, whether it accumulates into the necrotic liver, and the impact of its recognition by the immune system remains elusive. Here we showed that treatment with two different hepatotoxic compounds (acetaminophen and thioacetamide) caused DNA release to the hepatocyte cytoplasm, which occurred in parallel with cell death in vitro. Administration of these compounds in vivo caused massive DNA deposition within the liver necrotic areas, together with a widespread intravascular DNA coating. Using confocal intravital microscopy, we revealed that liver injury due to hepatotoxic overdose led to a directional migration of neutrophils to DNA-rich areas, where they exhibited an active patrolling behavior. DNA removal by intravenous DNASE1 injection or blockage of TLR9-mediated sensing significantly reduced systemic inflammation, liver neutrophil recruitment and hepatotoxicity. Analysis of liver leukocytes by flow cytometry revealed that emigrated neutrophils upregulated TLR9 expression in the plasma membrane during liver necrosis, and these cells sensed and reacted to extracellular DNA by up-regulating NF-κB and CXCR2 expression. Interestingly, adoptive transfer of wild-type neutrophils to TLR9-/- mice reversed the hepatoprotective phenotype otherwise observed in TLR9 absence. We concluded that hepatic DNA accumulation is a novel feature of DILI pathogenesis and blockage of DNA recognition by the innate immune system may consist in a promising therapeutic venue for DILI and FHA.