Disparate natural killer T cell subsets exhibit opposing regulatory effects on the cytokine storm.

Abstract

Abstract Inflammation is both a critical component of the immune system for effective clearance of microbial challenges and a mechanism by which some pathogens cause disease, e.g., tularemia, dengue fever, and COVID-19. The bacterium Francisella tularensis (Ft), the causative agent of tularemia, elicits a cytokine storm in which the immune system over-responds to the bacterium, releasing massive amounts of proinflammatory cytokines. Untreated, tularemia can reach a mortality rate as high as 30% in healthy adults with inhalation of as few as 10 colony forming units inducing respiratory tularemia. While Ftis spread from zoonotic sources in nature, the ease of aerosol spread and high mortality led to its weaponization and continued concern for bioterrorism applications. Natural Killer T (NKT) cells are important immune cells with the capability of modulating the inflammatory response. NKT cells are activated early following Ftinfection suggesting a role in the innate immune response in tularemia. NKT cells are categorized into two distinct subsets, type I and type II based on their antigen recognition, or not, of α-galactosylceramide. Literature suggests that these subsets have opposing regulatory phenotypes, however, a clear understanding of their roles in regulating inflammation remains unknown and an emerging frontier in NKT research. Our lab has observed opposing roles in suppressing the cytokine storm by NKT subtypes. Ongoing studies will elucidate the mechanism utilized to influence the cytokine storm. This project will yield a better understanding of NKT cell-mediated inflammation during Ftinfection and, more broadly, characterize their involvement and potential for therapeutic targeting for a number of NIH priority pathogens. Supported by grants from National Institute of General Medical Sciences (NIGMS) Research Initiative for Scientific Enhancement (RISE) grant R25 GM 06921-18