Telomere dysfunction impairs intestinal differentiation and predisposes to diet-induced colitis

Intestinal epithelium dysfunction causes barrier defects, malabsorption and dysbiosis, predicting local and systemic disease, morbidity and mortality in humans. However, the underlying causes are not well understood. Here we show that telomere shortening is a host intrinsic factor that impairs enterocyte differentiation. The presence of such undifferentiated enterocytes is associated with barrier disruption and malabsorption of nutrients, such as fructose. A fructose-rich diet causes increased fructose spillover to the colon and induces colitis in a microbiome-dependent manner. The microbiome uses fructose to synthesize essential metabolites, including NAD precursors, that complement the host’s low NAD pool in the inflamed colon. Thus, telomere shortening drives enterocyte dysfunction and predisposes to diet-induced colitis through barrier disruption, increased nutrient flux to the colon and modulation of the microbiome. This differerentiation defect expands the canonical stem cell failure-centered view of how telomere shortening impacts the intestine and predisposes to intestinal disease in conditions associated with short telomeres.