Schistosoma mansoni–Induced Oxidative Stress Triggers Hepatocellular ProliferationSummary

Background & Aims: Schistosomiasis is one of the most prominent parasite-induced infectious diseases, affecting more than 250 million people. Schistosoma mansoni causes metabolic exhaustion and a strong redox imbalance in the liver, causing parenchymal damage, and may predispose for cancer. We investigated whether oxidative stress provokes hepatocellular proliferation upon S. mansoni infection. Methods: The cell cycle, replication stress response, and proliferation were analyzed on transcriptional and protein levels in the livers of S. mansoni–infected hamsters and by mechanistic gain- and loss-of-function experiments in human hepatoma cells. Major results were validated in human biopsy specimens of S. mansoni–infected patients. Results: S. mansoni infection induced licensing factors of DNA replication and cell-cycle checkpoint cyclins in parallel with a DNA damage response in hamster hepatocytes. Moreover, even unisexual infection without egg effects, as a reflection of a chronic inflammatory process, resulted in a moderate activation of several cell-cycle markers. S. mansoni soluble egg antigens induced proliferation of human hepatoma cells that could be abolished by reduced glutathione. Conclusions: Our data suggest that hepatocellular proliferation is triggered by S. mansoni egg-induced oxidative stress.