Hematopoietic LTβR deficiency results in skewed T cell cytokine profiles during a mucosal viral infection.

The lymphotoxin signaling pathway plays an important role in the homeostasis and function of peripheral and mucosal dendritic cells, and dendritic cell-intrinsic lymphotoxin β receptor expression is required for optimal responses to opportunistic intestinal bacteria. However, it is unknown whether dendritic cell-intrinsic lymphotoxin β receptor signaling is required for responses to intestinal viral infections. We explored this question by orally administrating murine rotavirus to chimeric mice that lack lymphotoxin β receptor signaling in the myeloid compartment but retain lymphoid tissues. We found that although clearance of rotavirus was unimpaired in the lymphotoxin β receptor(-/-) → wild-type chimeric mice compared with wild-type → wild-type chimeric mice, IFN-γ-producing CD8(+) and CD4(+) T cells were significantly increased in the small intestinal lamina propria of lymphotoxin β receptor(-/-) → wild-type chimeric mice. In contrast, IL-17-producing CD4(+) T cells were reduced in lymphotoxin β receptor(-/-) → wild-type chimeric mice in the steady state, and this reduction persisted after rotavirus inoculation. In spite of this altered cytokine profile in the small intestinal lamina propria of lymphotoxin β receptor(-/-) → wild-type chimeric mice, the local production of rotavirus-specific IgA was unperturbed. Collectively, our results demonstrate that lymphotoxin β receptor signaling in radio-sensitive myeloid cells regulates the balance of IFN-γ and IL-17 cytokine production within the small intestinal lamina propria; however, these perturbations do not affect mucosal antiviral IgA responses.