Adenylate kinase 5, a novel genetic risk factor for Alzheimer’s disease, regulates microglial inflammatory activation

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by memory loss, cognitive decline, and neuroinflammation, primarily mediated by microglia. In this study, we investigate the role of adenylate kinase 5 (AK5) in microglial function and its association with AD-related pathology. Analysis of brain tissues from AD patients and AD model mice revealed a significant reduction in AK5 expression. In vitro knockdown of AK5 in microglial cells attenuated lipopolysaccharide-induced pro-inflammatory responses, including decreased nitric oxide and tumor necrosis factor-alpha production, while enhancing phagocytic activity. Moreover, AK5 silencing induced metabolic reprogramming, evidenced by reduced lipid droplet accumulation and adipose triglyceride lipase mRNA levels, alongside increased farnesoid X receptor mRNA expression. Genome-wide association studies further identified two AK5 single nucleotide polymorphisms (SNPs), rs59556669 and rs75224576, significantly associated with hippocampal and amygdala atrophy as well as increased AD risk. Notably, these SNPs were not in linkage disequilibrium with the apolipoprotein E (APOE) locus, suggesting that AK5 may represent an independent genetic risk factor for AD. Collectively, our findings identify AK5 as a key regulator of microglial immune and metabolic function. The presence of AK5 variants may contribute to AD susceptibility, and AK5 expression or genetic status could serve as a potential biomarker for early risk assessment. Further exploration of AK5-targeted interventions may provide new therapeutic avenues for AD prevention or treatment.