Effect of Invariant Natural Killer T cells on Mouse Gut Microbiota

Invariant Natural Killer T (iNKT) cells are unconventional T cells that respond to glycolipid antigens found in microbes in a CD1d-dependent manner. iNKT cell exert innate-like functions and produce copious amounts of cytokines, chemokines and cytotoxic molecules within only minutes of activation. As such, iNKT cells can fuel or dampen inflammation in a context-dependent manner. In addition, iNKT cells provide potent immunity against bacteria, virus, parasites and fungi. Although microbiota-iNKT cell interaction are not well-characterized, mounting evidence suggest that microbiota colonization early in life impacts their homeostasis and functions in disease. In this study, we showed that CD1d-/- and V14 Tg mice, which lack and have increased numbers of iNKT cells, respectively, had no alterations in gut microbiota composition compared to their littermate controls. Furthermore, specific iNKT cell activation by glycolipid antigens only resulted in a transient and minimal shift in composition, when compared to the natural drift found in our colony. Our findings demonstrate that iNKT cells have little to no influence in regulating commensal bacteria at steady state.