We started by testing the effect of an unhealthy diet, named here as Feast Diet (FD) on T cells and consequently on intestinal homeostasis in mouse models. We found that after a short consumption of FD, the intestinal microbiota and the T cell composition in the intestine and mucosal-associated lymphoid tissues (MALTs) were drastically impacted and consequently the intestinal homeostasis was compromised. This effect could be reverted by a switched to a “healthy” diet. This data show how rapid the capacity of the T cells to adapt to environmental changes is and consequently how they mediate the effect of the diet on our health.
In parallel, we studied the molecular mechanisms of T cell adaptability and found one key signaling pathway, namely TGFβR/SMADs, which regulates this mechanism. In essence, we have made one initial step toward the development of future immune therapies that could “force” the anti-inflammatory fate of Th17 cells by targeting these specific molecular mechanisms, and thereby possibly reset the homeostasis in inflamed tissues of patients affected by Th17 cell-mediated immune-mediated inflammatory diseases.
Finally, we found that short-term consumption of a diet rich in tryptophan led to an increased concentration of the microbiota-derived metabolite indole-3-acetic acid (3-IAA) in the circulation of mice. The combination of 3-IAA and chemotherapy, licensed by neutrophil-derived myeloperoxidase, increases oxidative stress, reduces autophagic activity and ultimately halts colon and pancreatic cancer cell proliferation. Translating these findings back to humans, we found a strong correlation between the concentration of 3-IAA and the response to chemotherapy in two independent cohorts of pancreatic cancer patients.