Floyd, Alexandria N.

Abstract Invariant Natural Killer T (iNKT) cells recognize glycolipid antigens presented on CD1d and rapidily respond to direct immune responses. iNKT cells develop in the thymus and migrate to peripheral tissues in what has been presumed to be differentiated/committed states. Accordingly, colonic iNKT cells are established in early life, considered to remain ‘fixed’ post-weaning, and determine life-long colitis susceptibility. Using single cell RNA sequencing (scRNA-seq), we demonstrate that humans and mice contain colonic iNKT populations transcriptionally resembling immature and intermediate thymic iNKT precursors. Contrary to prevailing paradigms, we demonstrate colonic iNKT cell populations expand in adult mice when CD1d expressing colonic goblet cells form goblet cell-associated antigen passages. Expansion preferentially affected intermediate iNKT cells, was durable, and protective in a colitis model. These studies reveal that the adult colon harbors iNKT cells with retained plasticity and uncover a novel role for goblet cells as unconventional antigen presenting cells regulating this axis.

Abstract Invariant natural killer T (iNKT) cells are unique innate immune cell which secrete cytokines and immune mediators. These cells recognize self or microbial glycolipids presented in the context of CD1d. iNKT cells can contribute to host protection or pathogenesis during intestinal inflammation. Colonic iNKT cells are established under the influence of the microbiota in early life and the current understanding is that colonic iNKT cells are fixed and not manipulable in later life. Goblet cells (GCs) or/and goblet cell associated passages (GAPs) deliver luminal antigens and maintain peripheral T regulatory cells in the steady state. However, GAPs in the colon are absent in adult mice due to GCs microbial sensing. We found that the glycolipids can be delivered through GAPs and that inducing GAPs in the colon in adult mice resulted in significant iNKT cell expansion. Deletion of GCs or deletion of CD1d on GCs prevented iNKT cell expansion suggesting a role for colonic GCs in presenting glycolipids to iNKT cells. Single cell RNA sequencing of colonic-iNKT cells showed significantly increased iNKT2 and iNKT1 subsets after colonic GAP induction. Proteomic analysis of these iNKT cells further confirmed the characteristics of expanded iNKT subsets. Moreover, iNKT cells expanding after colonic GAP induction persisted and were protective in DSS-induced colitis. Adoptive transfer of the expanded colonic iNKT cells protected in the DSS-induced colitis model, indicating that expanded colonic iNKT cells were sufficient for protection in this model. These findings indicate that colonic iNKT cells are not fixed during early life but can be expanded in a GAP dependent and GC CD1d dependent manner and can be protective in some models of colitis. Crohn’s and Colitis Foundation

Late-onset sepsis (LOS) is a highly consequential complication of preterm birth and is defined by a positive blood culture obtained after 72 h of age. The causative bacteria can be found in patients’ intestinal tracts days before dissemination, and cohort studies suggest reduced LOS risk in breastfed preterm infants through unknown mechanisms. Reduced concentrations of epidermal growth factor (EGF) of maternal origin within the intestinal tract of mice correlated to the translocation of a gut-resident human pathogen Escherichia coli , which spreads systemically and caused a rapid, fatal disease in pups. Translocation of Escherichia coli was associated with the formation of colonic goblet cell-associated antigen passages (GAPs), which translocate enteric bacteria across the intestinal epithelium. Thus, maternally derived EGF, and potentially other EGFR ligands, prevents dissemination of a gut-resident pathogen by inhibiting goblet cell-mediated bacterial translocation. Through manipulation of maternally derived EGF and alteration of the earliest gut defenses, we have developed an animal model of pathogen dissemination which recapitulates gut-origin neonatal LOS.