Oxidative Stress and Heat Stress in Experimental Amoebic Liver Abscess

Several species belonging to the Genus Entamoeba can colonize the mouth or the human gut; however, only Entamoeba histolytica is pathogenic to the host, causing amoebiasis. This illness leads to one hundred thousand deaths per year worldwide, affecting mainly underdeveloped countries in areas with poor sanitary conditions. Throughout its life cycle or during the invasion of human tissues, the parasite is constantly subjected to stress conditions. In in vitro culture, this microaerophilic parasite can tolerate up to 50 μM oxygen concentrations; however, during invasion the parasite has to cope with the higher oxygen content found in the blood and well perfused tissues (60–130 μM) and with reactive oxygen and nitrogen species (ROS and NOS, respectively) derived from both the host (as a first line of defense against the infection) and from the oxygen and nitrogen detoxification systems within the parasite. Furthermore, notwithstanding that host body temperatures (36.5–39 ℃) observed during amoebic liver infection affect amoebic growth in culture (~50% survival); during tissue invasion the parasite adapts to this stress and proliferates. In the present work, we analyzed the possible mechanisms by which E. histolytica resists the physiological stressors present during the host tissue invasion. It is also discussed that during the experimental amoebic liver abscess development in hamsters, several adaptation stages are occurring, including a host liver metabolic reprograming that creates a reductive environment that favors amoebic survival.