Neuroinflammation in Alzheimer's and Parkinson's diseases: pathogenic mechanisms and therapeutic strategies.

Abstract

Neuroinflammation is increasingly recognized as a key contributor and amplifier associated with the pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD). Neuroinflammation occurs throughout various stages of these diseases with expanding complexity. Currently, no effective therapies exist that specifically target neuroinflammatory processes in these disorders. In this review, we synthesize current understanding of central and peripheral inflammatory mechanisms implicated in both diseases. We illustrate how endogenous pathological triggers, such as amyloid-β (Aβ) peptide, hyperphosphorylated tau, and α-synuclein, activate glial cells, contributing to chronic neuroinflammation that exacerbates neurodegeneration. Additionally, peripheral factors, including systemic inflammation, environmental exposures, and gut-brain axis interactions, are discussed for their roles in modulating neuroinflammatory responses. Notably, the underappreciated roles of oligodendrocyte precursor cells and oligodendrocytes in neuroimmune crosstalk are also highlighted. Advanced methodologies, including glial cell imaging, single-cell transcriptomics, and human induced pluripotent stem cell-derived organoid models, are providing unprecedented insights into the molecular and cellular mechanisms underlying neuroinflammation. Finally, we evaluate emerging therapeutic strategies and ongoing clinical trials targeting neuroinflammatory pathways and analyze the potential of immunomodulatory approaches to slow disease progression. This comprehensive review emphasizes that precise targeting of neuroinflammation represents a tractable strategy for developing effective disease‑modifying treatments for AD and PD.