T cell trafficking to the small intestine in Cryptosporidium infection

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Project Summary The apicomplexan parasite Cryptosporidium is a leading cause of diarrhea and death due in immunocompromised individuals and malnourished children globally. Control of Cryptosporidium requires T cells to migrate to the small intestine. However, there are significant gaps in our understanding of the regulation of T cell responses against the parasite. This is in large part due to difficulties analyzing T cell populations in the gut, which is home to many activated cells at baseline. The Hunter and Striepen laboratories have developed a novel system for studying T cell responses by engineering Cryptosporidium to express both MHCI- and MHCII-restricted model antigens. This allows for the first-time identification of parasite- specific T cells within the gut, facilitating the study of T cell priming and trafficking. Using this system, I have found that cDC1s induce gut-homing integrins on T cells during Cryptosporidium infection. In addition, I have found evidence for changes in mLN DC ability to induce the canonical gut-homing integrin LPAM-1(⍺4β7) during infection compared to homeostasis, pointing to an infection-induced gene expression program in these DC, possibly related to their ability to produce retinoic acid. However, when LPAM-1 is blocked, mice still control infection at unchanged kinetics, indicating LPAM-1-independent mechanisms of T cell trafficking. Based on my preliminary data, I will investigate the effect of Cryptosporidium infection on dendritic cells in the intestinal mucosa and will ascertain the role of the integrin LPAM-1 and other homing molecules in resistance to Cryptosporidium. I will utilize a combination of novel transgenic parasites, genetic mouse models, single-cell RNA sequencing, and high-dimensional flow cytometry to address these aims. These studies will provide an opportunity to train in cross- disciplinary approaches in parasitology and immunology to better understand how immunity to infection in the gut is regulated. The studies proposed here will impact our fundamental understanding of mucosal immunology and drive the development treatment and prevention for an important source of childhood mortality.