Microglial phagocytosis is an energetically demanding process that plays a critical role in the removal of toxic protein aggregates in Alzheimer’s disease (AD). Recent evidence indicates that a switch in energy production from mitochondrial respiration to glycolysis disrupts this important protective microglial function and may provide therapeutic targets for AD. Here, we demonstrate that the translocator protein (TSPO) and a member of its mitochondrial complex, hexokinase-2 (HK), play critical roles in microglial respiratory-glycolytic metabolism and phagocytosis. Pharmacological and genetic loss-of-function experiments showed that TSPO is critical for microglial respiratory metabolism and energy supply for phagocytosis, and its expression is enriched in phagocytic microglia of AD mice. Meanwhile, HK controlled glycolytic metabolism and phagocytosis via mitochondrial binding or displacement. In cultured microglia, TSPO deletion impaired mitochondrial respiration and increased mitochondrial recruitment of HK, inducing a switch to glycolysis and reducing phagocytosis. To determine the functional significance of mitochondrial HK recruitment, we developed an optogenetic tool for reversible control of HK localization. Displacement of mitochondrial HK inhibited glycolysis and improved phagocytosis in TSPO-knockout microglia. Mitochondrial HK recruitment also coordinated the inflammatory switch to glycolysis that occurs in response to lipopolysaccharide in normal microglia. Interestingly, cytosolic HK increased phagocytosis independent of its metabolic activity, indicating an immune signaling function. Alzheimer’s beta amyloid drastically stimulated mitochondrial HK recruitment in cultured microglia, which may contribute to microglial dysfunction in AD. Thus, targeting mitochondrial HK may offer an immunotherapeutic approach to promote phagocytic microglial function in AD.

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) that prevails mainly in western countries. Due to the unknown etiology of UC, the purpose of treatments has predominantly comprised symptomatic and pain relief. With extensive research focusing on the pathogenesis of UC, various novel treatments have emerged, although their efficiency has remained unsatisfactory. Hedysarum multijugum Maxim (HMM), a crucial constituent of traditional Chinese medicine, has a broad application in many diseases and has been found beneficial for UC patients.Methods: In this study, network pharmacology and molecular docking analyses were applied to explore the potential mechanism of HMM treating UC. Active ingredients of HMM and target genes were acquired from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP).UC-related genes were obtained from three disease databases. Common genes were selected from these two gene sets, and a compound-genes network was drawn by Cytoscape. Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO) enrichment, and protein-protein interaction (PPI) analyses were performed to identify the essential pathways and proteins in UC.Results: A total of 121 genes were found related to UC and targeted by HMM. The GO and KEGG analyses showed that these genes were associated with inflammation and immune signaling pathways and inflammation-related biological processes (BP) such as the tumor necrosis factor (TNF) and PI3K-AKT signaling pathways. Four active ingredients (quercetin, kaempferol, formononetin, and isorhamnetin) and five genes (RELA, MAPK14, MAPK1, JUN, AKT1) were reserved after screening. Molecular docking further showed that the receptor had a high binding affinity with HMM active ingredients.Conclusions: This study revealed that HMM treats UC through four active ingredients (quercetin, kaempferol, formononetin, and isorhamnetin) targeting five hub genes (RELA, MAPK14, MAPK1, JUN, AKT1) by regulating the PI3K-AKT1 and TNF signaling pathways.