Mechanisms of Helminth-Mediated Host Immunomodulation: A History and Overview of Current Research and Potential Applicat

Parasite-host interactions have been investigated in-depth for years, leading to the discovery of numerous methods by which parasites communicate with and influence their host. One notable effect of these interactions is the ability of parasites to modulate the host immune system, presumably as an adaptation to allow for parasite survival and evasion of the host's defenses. While described in virtually all parasites, many investigations have focused on parasitic helminths, given their endoparasitic nature, resulting in a potentially longer-lasting host interaction as compared to ectoparasites, and given the extensive pathology associated with many helminth infections. Adaptations range from mechanical methods such as mucus production or elaboration of protective barriers, to more molecular means, such as the excretion of immunomodulatory products including proteins and extracellular vesicles. Here, we provide an overview of the immunomodulatory mechanisms utilized by parasitic helminths. We will begin with a brief introduction of the history of parasite-host interactions, followed by current research related to the host immune response to endoparasites, and helminth-host immunomodulation studies. We will conclude with a brief overview of the future directions of this research, and implications of these findings as related to human and animal health.