Hepatic microcirculation – A critical but neglected factor for the outcome of viral hepatitis☆

Aggravation of viral hepatitis by platelet-derived serotonin. Lang PA, Contaldo C, Georgiev P, El-Badry AM, Recher M, Kurrer M, Cervantes-Barragan L, Ludewig B, Calzascia T, Bolinger B, Merkler D, Odermatt B, Bader M, Graf R, Clavien PA, Hegazy AN, Löhning M, Harris NL, Ohashi PS, Hengartner H, Zinkernagel RM, Lang KS.

More than 500 million people worldwide are persistently infected with hepatitis B virus or hepatitis C virus. Although both viruses are poorly cytopathic, persistence of either virus carries a risk of chronic liver inflammation, potentially resulting in liver steatosis, liver cirrhosis, end-stage liver failure or hepatocellular carcinoma. Virus-specific T cells are a major determinant of the outcome of hepatitis, as they contribute to the early control of chronic hepatitis viruses, but they also mediate immunopathology during persistent virus infection. We have analyzed the role of platelet-derived vasoactive serotonin during virus-induced CD8(+) T cell-dependent immunopathological hepatitis in mice infected with the noncytopathic lymphocytic choriomeningitis virus. After virus infection, platelets were recruited to the liver, and their activation correlated with severely reduced sinusoidal microcirculation, delayed virus elimination and increased immunopathological liver cell damage. Lack of platelet-derived serotonin in serotonin-deficient mice normalized hepatic microcirculatory dysfunction, accelerated virus clearance in the liver and reduced CD8(+) T cell-dependent liver cell damage. In keeping with these observations, serotonin treatment of infected mice delayed entry of activated CD8(+) T cells into the liver, delayed virus control and aggravated immunopathological hepatitis. Thus, vasoactive serotonin supports virus persistence in the liver and aggravates virus-induced immunopathology.

[Abstract reproduced by permission of Nat Med 2008;14:756–761].