Dysfunctional Mitochondria in Microglia Drive Cognitive Aging and Neurodegeneration via cGAS-STING.

From metabolism to neurodegeneration: how microglial functional reprogramming drives neurodegenerative diseases

Microglia are brain-resident myeloid cells that maintain central nervous system homeostasis and respond dynamically to neuronal injury, protein aggregation, and alterations in the local metabolic environment. Single-cell and single-nucleus studies demonstrate that microglial responses in neurodegenerative diseases are highly heterogeneous and cannot be adequately explained by the classical M1/M2 polarization model. Increasing evidence further indicates that metabolic remodeling is not merely a consequence of activation but a determinant of microglial migration, phagocytosis, inflammatory signaling, redox balance, organelle function, and interactions with surrounding neural cells. In this review, we propose a microglial immunometabolic trajectory framework in which metabolic states are viewed as branching and potentially reversible determinants of cellular function rather than fixed stages of a universal disease pathway. We summarize how glucose metabolism, mitochondrial function, lipid metabolism, amino acid metabolism, lysosomal activity, and redox regulation shape microglial plasticity. We further examine relationships among transcriptionally defined states, including disease-associated microglia, microglia associated with neurodegeneration, lipid-droplet-accumulating microglia, and other disease-enriched populations, while emphasizing that transcriptional similarity does not necessarily imply metabolic function or lineage progression. Comparative evidence from Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis indicates that common metabolic regulators, including HIF-1α, mTOR, PKM2, TREM2, APOE, and NLRP3, exert disease-specific effects with unequal mechanistic support. We further distinguish associative metabolic signatures from intervention-based causal evidence and discuss limitations of animal models, immortalized cell lines, postmortem tissue, and induced pluripotent stem cell-derived microglia. Finally, we highlight the need for cell-specific, state-resolved, and temporally precise metabolic interventions that restore defined microglial functions without compromising physiological immune surveillance.

Metabolic Reprogramming of Brain Microglia: Implications for Aging and Aging‐Associated Neurodegenerative Diseases

Microglia, the resident macrophages of the central nervous system (CNS), are key players in maintaining brain and spinal cord homeostasis and protecting the CNS from damage and disease. During aging, the brain undergoes profound changes—including chronic low‐grade inflammation, synaptic dysfunction, and increased vulnerability to neurodegenerative diseases—all of which are closely related to alterations in microglial function. One emerging theme is that microglial metabolism is a crucial determinant of their immune and homeostatic activity. In this mini‐review, we explore how metabolic programs shape brain microglial behavior and how these processes change during aging and in neurodegenerative diseases. We first highlight the link between specific metabolic pathways and key microglial functions, including phagocytosis, cytokine production, and the oxidative stress response. We then discuss how microglial metabolism is reprogrammed during healthy aging and in Alzheimer's disease and Parkinson's disease, including sex‐specific differences. Finally, we examine regulators that influence microglial metabolic states and discuss how these pathways contribute to disease susceptibility and progression. Collectively, recent findings highlight the central role of metabolic reprogramming in shaping microglial responses during aging and in neurodegenerative diseases. We emphasize the need for integrative studies that consider microglial subsets, sex differences, disease context, and upstream molecular regulators to better understand how microglial metabolism contributes to brain health and pathology. A deeper understanding of these pathways may offer new opportunities for therapeutic strategies aimed at restoring microglial homeostasis and mitigating harmful neuroinflammatory processes.

Microglial immunometabolic reprogramming in Alzheimer's disease: From mitochondrial dysfunction and redox imbalance to NLRP3 inflammasome-driven neuroinflammation.

Alzheimer's disease (AD) is increasingly recognized as a disorder in which amyloid-β deposition and tau pathology interact with neuroinflammation and metabolic dysregulation. Although mitochondrial dysfunction, redox imbalance, and NLRP3 inflammasome activation have each been implicated in AD pathogenesis, their mechanistic continuity within microglial immunometabolic reprogramming remains insufficiently defined. This narrative review integrates mechanistic, preclinical, and human-relevant evidence to propose a stage-dependent mitochondrial dysfunction-redox imbalance-NLRP3 inflammasome axis. We discuss how AD-related stimuli shift microglia toward a pro-inflammatory metabolic phenotype; how impaired mitochondrial quality control promotes reactive oxygen species generation and oxidized mitochondrial DNA release; and how these signals facilitate NLRP3 inflammasome activation and sustained inflammatory amplification. We further summarize therapeutic strategies targeting upstream mitochondrial homeostasis, intermediate metabolic-redox coupling, and downstream NLRP3 signaling, while emphasizing the translational limitations and biomarker needs. We conclude that this proposed axis provides a testable stage-dependent framework for interpreting chronic, self-amplifying neuroinflammation in AD and may inform biomarker-guided, combinatorial therapeutic strategies.

Microglia extracellular traps (MiETs) in Neurodegeneration: Mechanisms, Evidence Gaps, and Untapped Therapeutic Promise.

Microglial mitophagy as an immunometabolic checkpoint in alzheimer's disease: linking mitochondrial quality control to neuroinflammation.

AD is a complex neurodegenerative disorder characterized by chronic neuroinflammation. Microglia, the brain's resident immune cells, centrally regulate AD pathophysiology. Recent studies have highlighted microglial mitophagy as an important interface linking mitochondrial quality control to innate immune responses.Intact mitophagy facilitates the timely clearance of damaged mitochondria, thereby limiting the release of mitochondrial DAMPs (e.g., mtDNA and mtROS) and helping restrain aberrant activation of the cGAS-STING pathway and the NLRP3 inflammasome.In the AD pathological milieu, however, factors including Aβ deposition, tau pathology, and genetic risk variants such as TREM2 and APOE4 disrupt mitophagy at multiple levels-from initiation and recognition to lysosomal degradation. This review systematically summarizes the molecular regulatory network of microglial mitophagy, with a particular focus on the mechanisms by which AD-associated pathological factors impair this process. We further discuss potential mechanisms through which mitophagic dysfunction may contribute to the amplification of neuroinflammation, including the release of mitochondrial DAMPs, the reprogramming of TBK1 signaling, and intercellular interactions. Finally, we outline current therapeutic strategies aimed at restoring mitophagy and discuss their potential to modulate neuroinflammatory responses and AD-related pathological processes, while highlighting the challenges and future directions in this emerging field.

Glycogen-Dependent Metabolic Reprogramming Regulates Microglial Activation and Dysfunction in Neurodegenerative Disease

Microglia are central regulators of neuroinflammation in Alzheimer’s disease (AD), yet how metabolic states modulate function remains unclear. Here we show that microglia from the APPNL-G-F mouse model revealed upregulation of glycolytic enzymes coinciding with onset of microglial activation. Surprisingly, this glycolytic shift occurred alongside reduced expression of glucose transporters, suggesting that extracellular glucose may not be the primary fuel source, implicating glycogenolysis as the potential metabolic driver. Consistent with this, significant microglial glycogen accumulation was noted in late disease, when cells exhibited features of metabolic exhaustion and functional impairment. Pharmacological inhibition of glycogenolysis blunted microglia responses to Abeta aggregates and markedly reduced Abeta uptake, confirming a functional role for glycogen metabolism in shaping microglial states. Together, these findings identify glycogen as a central regulator of microglial metabolic health and function, highlighting glycogen homeostasis as a potential therapeutic target for promoting Abeta clearance and preserving protective microglial functions in AD.