CCR5 as a key modulator in neurocognitive disorders

This integrative review explores the emerging role of CC chemokine receptor type 5 (CCR5) as a critical regulator of neuroinflammation, synaptic plasticity, and cognitive function in the central nervous system. Initially identified as an immune receptor and a co-receptor for HIV entry, CCR5 is now increasingly recognized for its multifaceted role across diverse neurocognitive disorders. CCR5 is upregulated in neurons and glial cells in multiple neurological disorders, including Alzheimer's disease (AD), HIV-associated neurocognitive disorder (HAND), traumatic brain injury (TBI), multiple sclerosis (MS), Lewy body dementia (LBD), Parkinson's disease (PD), Huntington's disease (HD), stroke, and vascular dementia (VaD), where it regulates neuroinflammatory cascades, neuronal injury, and cognitive function. CCR5 also interacts with disease-specific pathological mechanisms, including amyloidosis, tau phosphorylation, cofilin-actin rod formation, and dendritic spine degeneration. Both genetic and pharmacologic inhibition of CCR5 have been shown to reduce microglial and astrocyte activation, preserve blood-brain barrier integrity, restore synaptic plasticity, and enhance cognitive performance in various clinical and preclinical models. While the preponderance of studies supports CCR5 inhibition as a therapeutic strategy to mitigate neuroinflammation and cognitive decline, some research has reported a protective role of CCR5 in AD, PD, stroke, and VaD, highlighting the complexity of its function. The divergent findings emphasize the need for the consideration of genetic background, cell-type-specific mutation or inhibition, the low prevalence of the homozygous CCR5Δ32 mutation in association studies, and context-specific approaches in the design of future studies. Such considerations will be essential for advancing CCR5 targeted interventions in neurocognitive disorders.