SPARC (Secreted Protein Acidic and Rich in Cysteine) knockdown protects mice from acute liver injury by reducing vascular endothelial cell damage

ATORRASAGASTI C; MAZZOLINI G; BOVER L; VIEN L

Conferencia; Global Academic Programs (GAP) Conference; 2019

Background: Acute liver failure is a clinical syndrome characterized by the sudden onset of severe acute hepatitis. Pathophysiological mechanisms are not fully understood, and therapeutic approach is difficult. SPARC is an extracellular glycoprotein involved in many biological processes including cell interaction and adhesion. After injury, SPARC is overexpressed inducing different cellular processes. We have demonstrated that inhibition of SPARC expression results in attenuation of liver fibrosis after chronic injury. Aims: The aim of this study was to investigate the biological effects of SPARC in fulminant hepatitis and developed strategies to block SPARC.Methods: Two models of acute liver damage were used: concanavalin A (Con A) and the agonistic anti-CD95 antibody on SPARC wild type (SPARC+/+) and knockout (SPARC-/-) mice. Liver injury was assessed after different time point by H&E stain, TUNEL, IHC assay, FC analysis and ELISA for measure cytokines levels. Endothelial sinusoidal barrier preservation was evaluated by electronic microscopy. Hepatocyte and liver sinusoidal endothelial cells (LSEC) primary cultures from SPARC+/+ and SPARC-/- were used for in vitro assays. Results: SPARC was overexpressed after injury. Knockdown of SPARC decreased hepatic damage in both models. Liver tissue of SPARC-/- mice showed decrease necrosis, less apoptosis and less CD4+/CD8+ cells infiltration compared with SPARC+/+. Serum AST, ALT, IL-6 and TNFα levels were significantly lower in SPARC-/- and decrease TGFβ1 expression was found in SPARC-/-. ConA-treated SPARC-/- mice showed preservation and less activation of sinusoidal endothelial barrier that was clearly damage in SPARC+/+. LSEC primary cultured assays showed less activation and no alterations in actin cytoskeleton organization SPARC-/-conA-treated LSEC. Conclusions: SPARC plays a significant role in acute liver failure. Interventions to block SPARC, like monoclonal antibodies, are suggested as promising approaches for treatment. mAb against SPARC will be generate in MD Anderson monoclonal antibody facility and test in vitro in conA-treated LSEC.