Plasma interleukin-6 levels in patients with cirrhosis. Relationship to endotoxemia, tumor necrosis factor-alpha, and hyperdynamic circulation.

BACKGROUND: Liver cirrhosis with portal hypertension is associated with hyperdynamic circulation characterized by generalized vasodilatation and increased cardiac output and regional blood flows. Patients with liver cirrhosis present with increased levels of interleukin-6 (IL-6), which may inhibit vascular smooth-muscle contraction. We investigated whether increased plasma IL-6 levels contribute to the pathogenesis of hyperdynamic circulation observed in cirrhotic patients and whether they are correlated with plasma tumor necrosis factor-alpha (TNF-alpha) and endotoxin concentrations.

METHODS: In 58 consecutive cirrhotic patients and 34 healthy subjects the plasma concentrations of TNF-alpha and IL-6 were measured with enzyme-linked immunosorbent assay, and endotoxin determinations with a limulus assay. In addition, 52 cirrhotic patients underwent a hemodynamic study using Swan-Ganz catheterization.

RESULTS: Plasma TNF-alpha, IL-6, and endotoxin levels were significantly higher in cirrhotic patients than in healthy subjects (7.3 +/- 0.2 versus 5.8 +/- 0.1 pg/ml, 6.4 +/ 0.8 versus 2.0 +/- 0.2 pg/ml, and 7.6 +/- 1.2 versus 2.8 +/- 0.3 pg/ml, respectively; p < 0.01). In cirrhotic patients the plasma levels of TNF-alpha IL-6, and endotoxin progressively increased in relation to the severity of liver dysfunction (graded by Pugh's classification). A significant correlation was observed between plasma TNF-alpha and IL-6 levels (r = 0.48, p < 0.001), whereas no correlation was observed between plasma endotoxin levels and plasma TNF-alpha and IL-6 levels. Plasma IL-6 levels correlated negatively with systemic vascular resistance in patients with cirrhosis (r = 0.5, p < 0.01).

CONCLUSIONS: Plasma IL-6 levels are increased in patients with cirrhosis. The severity of liver cirrhosis is an important factor for the occurrence of increased IL-6 levels. IL-6 may play a role in the hyperdynamic circulation observed in patients with cirrhosis.