Researchers Uncover a Fatal Parasite’s Protective Mechanisms

November 28, 2018

Researchers from two Technion faculties have characterized the defense mechanisms of an intestinal parasite that kills approximately 100,000 people annually. The discovery could lead to the development of drugs that will eliminate the parasite from patient bodies. Published in the October 2018 issue of PLOS Pathogens, the research was led by Associate Professor Serge Ankri and Ph.D. student Yana Shaulov from the Technion’s Rappaport School of Medicine, and Assistant Professor Ayelet Lamm from the Technion Faculty of Biology.

Entamoeba histolytica (EH) is a single-celled intestinal parasite found in the gut of millions of people. After invading the human body through contaminated water and food, it settles in the large intestine and liver and feeds off of live bacteria.

In most cases, the parasite lives in the gut without causing any damage to the host, but in certain cases, amebiasis develops. This disease can cause bloody diarrhea and invasion into the liver and other organs, and eventually to host death. The current research sought to identify how EH evades the host defense systems. The Technion researchers found that the answer is connected to Escherichia coli — one of the most prevalent intestinal bacteria. They discovered that this bacterium protects the parasite from oxidative stress. E. coli confers parasite resistance to oxidative stress via an enzyme called malate dehydrogenase and its product, oxaloacetate. The researchers demonstrated that the same mechanism protects another organism — the C. elegans worm.

The findings have been warmly received by members of the medical community. Professor David Leitsch from the Medical University of Vienna, who was not involved in this study, wrote that “in recent years, we have learned a lot about the interplay of intestinal parasites such as EH and gut bacteria. The implications are manifold and include altered pathogenicity of the parasites and resistance to oxidative stress or defence measures of the host, respectively. In a very interesting suite of two papers, the lab of Serge Ankri at the Technion discovered the impact of E. coli on resistance to oxidative stress in E. histolytica and … the authors convincingly demonstrate that the protective effect of E. coli is due to oxaloacetate.”

The researchers project that discovery of this mechanism will lead to the development of drugs that will impair this protective mechanism, will eliminate the parasite and curb onset of the disease.

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