Thrombospondin‐1 worsens acetaminophen‐induced acute liver failure in mice through its activation of TGFβ1

Abstract

IntroductionAcute liver failure results from a significant loss of liver function and has few effective treatments and poor clinical outcomes. Previously we have demonstrated that transforming growth factor beta 1 (TGFβ1) is upregulated during azoxymethane‐induced acute liver failure in mice and this signaling pathway promotes hepatic encephalopathy progression. Recently TGFβ1 has been shown to promote acetaminophen‐induced liver injury by promoting senescence of hepatocytes. TGFβ1 requires interactions with other proteins, such as thrombospondin‐1 (TSP‐1), to become activated and to be capable of binding its receptors. Therefore, we hypothesize that TSP‐1 activates TGFβ1 during acetaminophen‐induced acute liver failure worsening outcomes.MethodsMale C57Bl/6 mice or TSP‐1 knockout mice were injected with acetaminophen (APAP; 300 and 600 mg/kg) to generate acute liver injury. APAP‐treated mice had serum and liver collected at up to 24 hours post injection. Liver pathology was assessed by H&E staining, TUNEL staining, malondialdehyde assay, glutathione assay, nitrotyrosine expression and transaminase assessments. TGFβ1, TSP‐1, IL‐1β, IL‐6, TNF‐α, SOD1, iNOS and phosphorylated/total JNK expression were assessed by immunoblotting, immunohistochemistry, immunofluorescence, ELISA and/or real‐time PCR assays.ResultsMice injected with APAP had elevated hepatic TGFβ1 and TSP‐1 levels, which co‐localized primarily to hepatocytes. APAP‐treated mice with genetic knockout of TSP‐1 had reduced hepatic injury and hepatocyte necrosis as evident by improved serum transaminases, restored glutathione levels, reduced phosphorylated JNK signaling and less TUNEL staining compared to wildtype APAP‐treated mice. Expression of oxidative and nitrosative stress markers, as well as proinflammatory cytokines, were reduced in TSP‐1 knockout mice compared to wildtype mice administered APAP.ConclusionsStrategies employed to reduce TSP‐1 signaling in APAP‐treated mice reduced liver damage and pathology. Therefore, targeting TSP‐1 signaling may be a novel therapeutic target for the management of APAP‐induced acute liver failure.Support or Funding InformationThis study was funded by NIH R01 awards (DK082435 and DK112803) and a VA Merit award (BX002638) from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service to Dr. DeMorrow. This study was also funded by a VA Career Development award (BX003486) from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service to Dr. McMillin.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.