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To investigate the relationship between NF-kappaB activation and hepatic stellate cell (HSC) apoptosis in hepatosplenic schistosomiasis, hepatic biopsies from patients with Schistosoma mansoni-induced periportal fibrosis, hepatitis C virus-induced cirrhosis, and normal liver were submitted to alpha-smooth muscle actin (alpha-SMA) and NF-kappaB p65 immunohistochemistry, as well as to NF-kappaB Southwestern histochemistry and TUNEL assay. The numbers of alpha-SMA-positive cells and NF-kappaB- and NF-kappaB p65-positive HSC nuclei were reduced in schistosomal fibrosis relative to liver cirrhosis. In addition, increased HSC NF-kappaB p65 and TUNEL labeling was observed in schistosomiasis when compared to cirrhosis.These results suggest a possible relationship between the slight activation of the NF-kappaB complex and the increase of apoptotic HSC number in schistosome-induced fibrosis, taking place to a reduced HSC number in schistosomiasis in relation to liver cirrhosis. Therefore, the NF-kappaB pathway may constitute an important down-regulatory mechanism in the pathogenesis of human schistosomiasis mansoni, although further studies are needed to refine the understanding of this process.

This study compares the populations of liver mesenchymal cells (LMCs) and their proliferative activity in schistosomal periportal fibrosis and in hepatitis C virus-induced cirrhosis. LMCs were evaluated by immunohistochemical double staining for proliferating cell nuclear antigen (PCNA) and alpha-smooth muscle actin (alpha-SMA) or glial fibrillary acid protein (GFAP) in liver biopsies from humans with schistosomal fibrosis (n=40), hepatitis C virus-induced cirrhosis (n=20), and normal controls (n=20). The number of LMCs was found to be higher in schistosomal fibrosis than in the normal liver, but lower than in cirrhosis. alpha-SMA- and GFAP-positive cells were increased in both diseases, but more so in cirrhosis. In cirrhotic liver, alpha-SMA-positive cells were highly predominant in relation to GFAP-positive cells. However, there was an inverted ratio between these cells in schistosomiasis as compared to cirrhosis. The PCNA labeling index was higher in alpha-SMA-positive cells than in GFAP-positive cells, and did not differ between pipe-stem fibrosis and liver cirrhosis regarding alpha-SMA- or GFAP-positive cells. The predominance of GFAP-positive cells observed in schistosomiasis suggests that hepatic stellate cells (HSCs) have a major role in connective tissue deposition in the human schistosomal liver. On the other hand, the smaller number of LMCs in schistosomal fibrosis in comparison to liver cirrhosis may be related to mild and limited injury due to the schistosomal egg-induced inflammatory response. The granulomatous inflammation around Schistosoma mansoni eggs appears to mobilize and activate a reduced number of mesenchymal cells in comparison to the scattered necro-inflammatory reaction produced by the hepatitis C virus.