Targeting gut microbiota to alleviate neuroinflammation in Alzheimer’s disease

The gut microbiota for targeting neuroinflammation in AD. Three sites of inflammation are conceivable in AD: hyper-reactive microglia and astrocytes in the brain, peripheral inflammation, and inflammatory processes in the gut and mediators of this inter-organ communication as e.g. the vagus nerve or soluble factors acting via the blood or lymphatic system. All three sites offer routes for interfering by using knowledge on our microbial commensals and their impact on neuroinflammation (image created with biorender.com). [Display omitted] The gut microbiota came into focus within the last years regarding being associated with or even underlying neuropsychiatric diseases. The existence of the gut-brain-axis makes it highly plausible that bacterial metabolites or toxins that escape the intestinal environment or approach the vagal connections towards the brain, exert devastating effects on the central nervous system. In Alzheimer’s disease (AD), growing evidence for dysbiotic changes in the gut microbiota is obtained, even though the question for cause or consequence remains open. Nevertheless, using modulation of microbiota to address inflammatory processes seems an attractive therapeutic approach as certain microbial products such as short chain fatty acids have been proven to exert beneficial cognitive effects. In this review, we summarize, contemporary knowledge on neuroinflammation and inflammatory processes within the brain and even more detailed in the gut in AD, try to conclude whom to target regarding human microbial commensals and report on current interventional trials.