Early-life high-fat diet-induced obesity programs hippocampal development and cognitive functions via regulation of gut commensal Akkermansia muciniphila.

Obesity is one of the most serious public health challenges in the world. Obesity during early life has been associated with an increased risk of neurodevelopmental disorders, including deficits in learning and memory, yet the underlying mechanisms remain unclear. Here, we show that early life high-fat diet (HFD) feeding impairs hippocampus-dependent contextual/spatial learning and memory, and alters the gut microbiota, particularly by depleting Akkermansia muciniphila (A. muciniphila), in mice. Transplantation of the HFD microbiota confers hippocampus-dependent learning and memory deficits to mice fed a chow diet. Oral treatment of HFD-fed mice with the gut commensal A. muciniphila corrects gut permeability, reduces hippocampal microgliosis and proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6) expression, and restores neuronal development and synapse plasticity, thus ameliorates defects in learning and memory. Interestingly, treatment of mice with lipopolysaccharide (LPS) mimics HFD-induced hippocampus-dependent cognitive impairment in chow-fed mice. In line with these findings, pharmacologic blockade of Toll-like receptor 4 (TLR4) signalling or antibiotics treatment both effectively prevent hippocampus-dependent learning and memory deficits in HFD-fed mice. Collectively, our findings demonstrate an unexpected pivotal role of gut microbiota in HFD-induced cognitive deficits and identify a potential probiotic therapy for obesity associated with cognitive dysfunction during early life.