Direct evidence of microbiota-gut-inflammasome-brain axis comes from a study by Shen et al., which shows that fecal transplantation from AD patients in APP/PS1 transgenic mice induces the activation of gut NLRP3 inflammasome and the production of proinflammatory cytokines, which further aggravate neuroinflammation and cognitive deficits [30]. Here, APP is linked to Alzheimer disease.