Analysis of the gut microbiome to validate a mouse model of pellagra

Pellagra is caused by an abnormal intake and/or use of niacin, but its phenotypes are diverse. The phenotypes of pellagra can also be atypical, such as nausea. We previously reported a mouse model of pellagra-related nausea. However, the mechanism of this model is unclear. In this study, we found that the gut microbiota, which is thought to be a source of niacin, played an important role in the development of pellagra-related nausea in germ-free mice. We also investigated the gut microbiome. We compared urinary niacin metabolite levels and the dermal response between mice fed a normal diet and those fed a low-niacin diet to investigate the putative trigger of pellagra. Epoxyeicosatrienoic and hydroxyeicosatetraenoic acid levels were higher in mice fed a low-niacin diet compared with those fed a normal diet. Furthermore, histological studies indicated a dermatological response to the low-niacin diet. Interestingly, higher levels of oxidised fatty acids in response to the germ-free state were also observed. These findings indicate successful establishment of our newly established mouse model of pellagra via the gut microbiota. We believe that this model could enable the discovery of the putative cause of pellagra and phenotypes of pellagra that have not been recognised yet.