Oxygen and Redox Reactions Contribute to the Protection of Free-Living and Parasite Helminths against Pathogens and/or Host Response

Abstract

Millions of years ago, the reductive atmosphere environment of Earth was replaced by an oxidative one because of redox reactions. These conditions allowed aerobic organisms to populate the planet and control the toxicity of oxygen. Aerobic organisms began to produce reactive oxygen species (ROS) via oxygen redox reactions and used them for their physiology process. Free-living helminths appeared in the early Paleozoic era and parasite helminths in the late same era. Free-living helminths, such as Caenorhabditis elegans and earthworms, have been used as host models to understand their micro pathogen defenses, particularly those associated with ROS. We speculate that the micro pathogens of C. elegans are equivalent to the parasite helminth hosts in terms of generating a worm’s defense response. Therefore, parasite helminths may share similar defense mechanisms to humans, as in C. elegans. This last observation suggests the existence of a conservative pathogen protection process for centuries. This review discusses the evolution of oxygen molecules and redox reactions, as well as of the Earth’s atmosphere, and changes over time in the protection of helminths mechanisms. These mechanisms have been so successful that have improved our understanding and have had a positive impact on humans.