Study deepens understanding of a dangerous parasite
Schistosoma haematobium (S. haematobium) is a parasite that is originally distributed in Africa and the Middle East. It triggers urogenital schistosomiasis, a debilitating disease affecting as many as 112 million people. In addition, it is found to strongly correlate with bladder cancer. In a word, S. haematobium severely threatens human health.
According to a study published last week in the journal Infection and Immunity, S. haematobium produces a protein termed H-IPSE, which can enter host cells, causing tissue damage and disease spread. Notably, the expression of H-IPSE is restricted to the egg stage of female adult parasites. The study, carried out by a group of scientists from Stanford University, University of Nottingham, Biomedical Research Institute, and University of California, deepens our understanding of the relationship between host cells and S. haematobium.
Franco Falcone, lead researcher of the study and associate professor of the University of Nottingham, believes that their findings will enable the development of vaccines and therapies to combat severe S. haematobium infections.
The life cycle of S. haematobium is very complex. The parasite has both an intermediate and a definitive host. Freshwater snails are an intermediate host for it, and mammals are the most important definitive host. People get infected when they contact with water containing cercariae released from infected snails. The cercariae enter the body, spread, grow, and reproduce. The parasites usually live in blood vessels in human bladder. At the egg stage, female adult parasites produce eggs, which penetrate the bladder walls to be excreted in the urine. Many of the eggs become trapped in tissues, triggering inflammatory responses. This is the major pathogenesis of S. haematobium-associated diseases.
Falcone and colleagues found that S. haematobium expresses multiple variants of H-IPSE protein and that H-IPSE protein is only detectable in mature eggs but not adults. They also found that H-IPSE protein is able to enter host cells and translocate to the nucleus, where it is likely to act as a transcription factor. These data suggest that H-IPSE may aid egg egress by weakening tissue.
Although more research is needed to verify the findings, the study has implications to the research and treatment of diseases caused by S. haematobium.