A systemic mechanism of increased transendothelial migration of leukocytes through the blood-brain barrier in hepatic encephalopathy.

Background: Hepatic encephalopathy (HE) is a frequent neurological complication of cirrhosis. Evidence suggests a synergic pathophysiological implication of hyperammonemia and systemic inflammation. In addition, the blood-brain barrier (BBB) permeability can be impaired in cirrhotic patients, notably in those displaying HE. We hypothesized that systemic inflammation could trigger leukocytes transendothelial migration (TEM) through the BBB in cirrhotic patients and especially those with HE.

Methods: We studied the effects of patients' plasma on the TEM of the leukocyte U937 cell line in vitro, using a validated BBB model (hCMEC/D3 cell line). We compared TEM of U937 leukocytes across hCMEC/D3 monolayer incubated with the plasma of i) patients with cirrhosis without HE, ii) patients with cirrhosis and HE, iii) healthy controls.

Results: We show that the plasma of cirrhotic patients with HE enhances TEM of U937 leukocytes across hCMEC/D3 BBB model. We found a correlation between U937 TEM on the one hand, the West-Haven score and ammonemia on the other one. A trend towards a correlation between U937 TEM and PS-100Beta in plasma, a marker of BBB solute's permeability increase, was also found.

Conclusion: These findings suggest that circulating factors could increase leukocytes TEM in cirrhotic patients and contribute to the increased BBB permeability that has been described in cirrhotic patients with HE.