Neuroinflammation as a Double-Edged Sword in the Central Nervous System: Cellular, Molecular, and Temporal Determinants of Neurodegeneration

Abstract

Background: Neuroinflammation is a tightly regulated biological response in the central nervous system (CNS), serving as both a protective mechanism and a driver of pathological progression. Under physiological conditions, it supports immune surveillance, synaptic remodelling, and tissue repair. However, when dysregulated or chronically sustained, it disrupts neuronal homeostasis and accelerates neurodegenerative cascades. Objective: This review examines the cellular, molecular, and temporal frameworks that dictate inflammatory outcomes in the CNS and delineates the mechanistic boundaries between acute resolution and chronic neurotoxicity. Methodology: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for narrative reviews, the review synthesised peer-reviewed literature on glial biology, cytokine signalling, phase-specific immune dynamics, and biomarker strategies. Thematic analysis was used to integrate findings across cellular, molecular, and temporal domains. Results: Resident glia, particularly microglia and astrocytes, coordinate dynamic cross-talk with neurons, vascular elements, and peripherally derived immune cells. Their activation states are governed by pattern-recognition receptors, intracellular signalling cascades, and cytokine networks that shift between reparative and destructive phenotypes depending on contextual cues and exposure duration. Neuroinflammation is a dynamic, context-dependent process. Precision immunomodulation guided by cellular specificity, temporal staging, and molecular profiling offers a more viable therapeutic pathway than broad immunosuppression. Conclusion: This review outlines actionable research priorities for next-generation CNS therapeutics. Recommendations: Prioritise phase-specific immunomodulation over broad immunosuppression to preserve protective clearance mechanisms; and integrate multi-omics and fluid biomarker profiling for precise patient stratification in clinical trials.