Serum osteopontin levels as a predictor of portal inflammation in patients with nonalcoholic fatty liver disease

BackgroundOsteopontin is a secreted phosphorylated glycoprotein that is expressed by a variety of cell types and that mediates numerous and diverse biological functions.Osteopontin knockout mice are protected from obesity-induced hepatic steatosis. In the present study, we sought to investigate whether serum osteopontin concentrations are associated with liver histology in patients with nonalcoholic fatty liver disease.MethodsSerum levels of osteopontin were measured by enzyme-linked immunosorbent assay in 179 well-characterized patients with nonalcoholic fatty liver referred for liver histology and 123 control subjects.ResultsSerum osteopontin levels were markedly higher in patients with nonalcoholic fatty liver disease than in controls (p < 0.001). Multivariable analysis showed that osteopontin levels were strongly and independently associated with both portal inflammation (β = 0.294, p < 0.01) and serum aminotransferase levels (aspartate aminotransferase: β = 0.295, p < 0.01; alanine aminotransferase; β = 0.285, p < 0.01).ConclusionIn summary, these data demonstrate that serum levels of osteopontin are elevated in nonalcoholic fatty liver disease and are a significant independent predictor of portal inflammation in this clinical entity.