Figure 4.

Potential mechanisms of interaction between HFD and chronic diseases via LPS. LPS, a structural component of the outer membrane of gram‐negative bacteria, penetrate the intestinal wall and reaches the corresponding tissues such as the blood systemic circulation and brain. TLR4 is expressed in immune cells, adipocytes, glial cells, and other cells. Hence, LPS causes inflammation via NF‐κB, thus promoting obesity and brain degeneration. Furthermore, LPS inhibits the expression of BDNF and CREB phosphorylation, and inhibits the expression level of synapsin‐1 in the brain. BDNF, brain derived neurotrophic factor; CD14, cluster of differentiation 14; CREB, cAMP response element‐binding protein; IL‐6, interleukin 6; IL‐1β, interleukin 1β; LPS, lipopolysaccharide; NF‐κB, nuclear factor κB; TLR4, Toll‐like receptor 4; TNF‐α, tumor necrosis factor α.