Early life γδT cell activation enforces intestinal barrier integrity during intergenerational C. difficile colonization

Thurairajah, B.; Westfall, S.; Chiggiato, L.; Keogh, L.; Sinha, A.; Olsen, K.; Tafesse, Y.; Lypaczewski, P.; Fontes, G.; Shapiro, B. J.; Cousineau, B.; Gruenheid, S.; Vermijlen, D.; Castagner, B.; Saliba, A.-E.; King, I. L.

doi:10.64898/2026.04.28.721483

bioRxiv · 10.64898/2026.04.28.721483

Early life γδT cell activation enforces intestinal barrier integrity during intergenerational C. difficile colonization

Thurairajah, B.·Westfall, S.·Chiggiato, L.·Keogh, L.·Sinha, A.·Olsen, K.·Tafesse, Y.·Lypaczewski, P.·Fontes, G.·Shapiro, B. J.·Cousineau, B.·Gruenheid, S.·Vermijlen, D.·Castagner, B.·Saliba, A.-E.·King, I. L.

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Abstract

Early postnatal life is a highly dynamic period in which the intestine is inundated with billions of microbes that not only battle for colonization, but also strongly influence immune system function and long-term health. This brief period of development provides a window of opportunity to imprint resilience against disease, yet the intercellular dialogue that dictates tissue protection are only beginning to be discovered. By performing a kinetic analysis of immune cell activation in the colon of mice from early life to adulthood, we identified transient activation of a microbiota-dependent type 3 immune response during the weaning period. This response was characterized by a selective increase in IL-17 production by fetal-derived {gamma}{delta} T cells that occurred in an IL-1 receptor-dependent, cell-intrinsic manner. The subsequent differentiation of IL-10 producing Ror{gamma}t+ T regulatory cells extinguished IL-17 production by {gamma}{delta} T cells and prevented immunopathology. Microbial gain-of-function approaches determined that colonic {gamma}{delta} T cell activation occurred in response to passive acquisition of C. difficile at birth. In turn, IL-17 limited C. difficile growth and intestinal barrier breach by the commensal microbiota. Collectively, our results reveal how an agile immune cell network meets the demands of a maturing microbiota to support gut health during early life. Highlights- Colonic {gamma}{delta}17 T cells are activated during early life in a microbiota-specific manner - Fetal-derived {gamma}{delta}17 T cells require IL-1 signals for activation - Passive acquisition of C.difficile induces {gamma}{delta}17 T cell activation - IL-17 limits C. difficile growth and systemic dissemination of commensals

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Thurairajah, B., Westfall, S., Chiggiato, L., Keogh, L., Sinha, A., Olsen, K., Tafesse, Y., Lypaczewski, P., Fontes, G., Shapiro, B. J., Cousineau, B., Gruenheid, S., Vermijlen, D., Castagner, B., Saliba, A.-E., King, I. L.. 2026-05-01. Early life γδT cell activation enforces intestinal barrier integrity during intergenerational C. difficile colonization. https://doi.org/10.64898/2026.04.28.721483

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