Expression and cellular localization of fibrillin-1 in normal and pathological human liver

Background: The expression and the distribution of fibrillin-1 and elastin were studied in normal and pathological human liver samples. Methods: As controls, histologically normal/subnormal liver samples (n=24) were used. Pathological samples corresponded to seven cirrhosis and eight hepatocellular carcinomas (HCC) developed on cirrhotic (four) or non-cirrhotic (four) liver. Results: In normal liver, fibrillin-1 and elastin co-localized in vessel walls and portal tract connective tissue. Fibrillin-1 alone was detected along sinusoids and in portal spaces at the interface with the limiting hepatocytic plates and close to the basement membrane of bile ducts. By transmission electron microscopy, typical bundles of microfibrils were detected both in Disse space and in portal zones. Cirrhotic nodules were usually rich in fibrillin-1 along sinusoids; fibrillin-1 and elastin were co-localized in fibrotic septa surrounding nodules. In HCC, fibrillin-1 was present between tumoral hepatocytes; stromal reaction around the tumors contained both fibrillin-1 and elastin. Conclusions: Fibrillin-1 was associated with elastin in portal mesenchyme and vessel walls of normal liver, in fibrotic septa around cirrhotic nodules and stromal reaction around HCC, but was expressed alone in the perisinusoidal space. The functional roles for fibrillin-1 in non-elastic tissues, such as the liver, remain to be elucidated.