Resumen de Stress Response in Entamoeba histolytica
Alfonso Olivos-García, Emma Saavedra, Erika Rubí Luis-García, Mario Nequiz, Ruy Pérez Tamayo
Several species belonging to the genus Entamoeba can colonize the mouth or the human gut; only Entamoeba histolytica, however, is pathogenic to the host, causing the disease amebiasis. This illness is responsible for one hundred thousand human deaths per year worldwide, affecting mainly underdeveloped countries. Throughout its entire life cycle, or invasion of human tissues, the parasite is constantly subjected to stress conditions. Under in vitro culture, this microaerophilic parasite can tolerate up to 5% oxygen concentrations; however, during tissue invasion the parasite has to cope with the higher oxygen content found in well perfused tissues (4-14%) and with reactive oxygen and nitrogen species (ROS and NOS, respectively) derived from both host and parasite. In almost all living cells, a low-dose, tightly regulated generation of ROS and NOS mediates several physiological functions such as growth, differentiation and metabolism; an excess of ROS and NOS, however, damages DNA, proteins and lipids, leading to cell death. In this chapter we review the latest findings regarding the physiological and pathological molecular functions of oxidative and nitrosative stresses in E. histolytica and discuss whether the molecules involved in the antioxidant system of the parasite can be appropriate drug targets for the treatment of amebiasis.
