Neutrophilic infiltration in alcoholic hepatitis

Leukocyte infiltration in the liver is one of the most important features of alcoholic liver disease. However, in alcoholic hepatitis, the role of polymorphonuclear neutrophils (PMNs) in liver injury still remains to be fully elucidated. Furthermore, the migration of PMNs and their presence in the liver during alcoholic hepatitis have not been fully investigated. Up-regulation of chemokine secretion and adhesion molecule expression on effector cells (i.e., PMNs) and target cells (i.e., hepatocytes) are important factors in neutrophilic infiltration of the liver. The CXC chemokines--that is, interleukin (IL)-8 (in human beings), cytokine-induced neutrophil chemoattractant (CINC) (in rats), and KC (in mice)--are proneutrophilic agents. They are up-regulated during chronic--that is, several years of--alcohol use in human beings and in up to 30 weeks in experimental models of ethanol intoxication in mice and rats. Up-regulation of these chemokines in the circulation and tissues is also associated with enhanced neutrophilic infiltration in the liver. In the rat, the up-regulation of CXC chemokine production is time dependent. For example, after 16 weeks of feeding, up-regulation of CXC chemokine is observed, whereas after 32 weeks, CC chemokines are enhanced. Concomitantly, selective migration of PMNs and mononuclear cells is observed. In another model, in which both CXC and CC chemokines were enhanced after chronic ethanol use for 12 weeks in mice, neutrophilic and mononuclear/lymphocytic infiltrations were also seen. This model correlates closely with alcoholic hepatitis in human beings, characterized by increased IL-8, RANTES (regulated upon activation, normal T cell expressed and secreted), and macrophage inflammatory protein-1 (MIP-1) and profound increases in neutrophils and lymphocytes in the liver.