Plasma lipid promotes immune suppression

A lipid molecule elevated in the blood of individuals with a type of cirrhosis (a form of advanced liver disease) is associated with immune suppression, according to a study published this week in Nature Medicine. In mice with liver disease, reducing the levels of this lipid with albumin can reduce the risk of infection, suggesting additional clinical trials are warranted regarding the use of albumin in immunosuppressed individuals with liver disease.

Patients with cirrhosis can develop scarring and poor liver function, and are at an increased risk of infection; however, the mechanism underlying immune suppression in these patients remains unclear.

Derek W Gilroy and colleagues found that the concentration of PGE2, a lipid molecule released from immune cells, was elevated in the blood of patients with two forms of cirrhosis: acutely decompensated cirrhosis and end-stage liver disease. Blood samples from these patients impaired the function of immune cells in culture and reduced their ability to kill bacteria. Albumin, a protein commonly found in the blood, is reduced in patients with liver disease and can reduce levels of PGE2 as well. Addition of albumin to the cultured immune cells reversed these suppressive effects. In two mouse models of liver disease, administration of albumin improved the survival of mice with liver disease following an infectious challenge with Group B Streptococcus.