Neurovascular Dysfunction and Glymphatic Impairment: An Unexplored Therapeutic Frontier in Neurodegeneration
Abstract
1. Introduction
2. Methodology of Literature Search
3. Pathophysiology of Neurovascular Unit Dysfunction
3.1. From Components to Pericyte-Driven Pathology
3.2. Vascular Endothelial Growth Factor as a Dual-Acting Therapeutic Target
3.3. The Glymphatic-Lymphatic Interface
3.4. Aquaporin-4 Polarity Loss: A Therapeutic Target
3.5. Meningeal Lymphatic Vessels: A Novel Drainage Target
4. Neuroinflammation and the Tripartite Synapse
4.1. Microglial Dysfunction and Synaptic Clearance
4.2. Complement-Mediated Synaptic Pruning
4.3. MicroRNA-Mediated Inflammation Control
5. Discussion
5.1. Inadequacy of Protein-Centric Approaches
5.2. Blood–Brain Barrier Permeability as an Overlooked Target
5.3. Inflammation-Mediated Neurovascular Damage
5.4. Precision Medicine Approaches to Neurovascular Dysfunction
| Therapeutic Target | Mechanism of Action | Preclinical Evidence | Proposed Therapeutic Approach | Potential Benefits | Challenges/Considerations | Key References |
|---|---|---|---|---|---|---|
| PDGF-BB/PDGFRβ Signaling | Maintains pericyte survival and BBB integrity via ERK and PI3K pathways | PDGFRβ ± mice show accelerated BBB breakdown and neurodegeneration; restoration protects against vascular damage | PDGF-BB supplementation; prevention of PDGFRβ shedding; APOE4-targeted interventions | Preserves pericyte coverage; maintains BBB integrity; prevents early vascular damage | Timing critical; systemic effects; optimal dosing unclear | [35,78] |
| VEGF-C/VEGFR-3 Signaling | Enhances meningeal lymphatic vessel function and promotes lymphangiogenesis for brain waste clearance | VEGF-C administration in AD mice increases mLV diameter, reduces CSF and brain Aβ, restores cognition | Recombinant VEGF-C (intrathecal or systemic); VEGFR-3 agonists; transcranial radiofrequency stimulation | Enhances protein clearance; reduces tau and Aβ accumulation; improves cognitive function | Delivery route optimization; potential angiogenic effects; dose-finding needed | [30,31] |
| AQP4 Polarization Restoration | Restores proper localization of AQP4 at perivascular astrocytic endfeet to enhance glymphatic flow | Exercise and calmodulin inhibition restore AQP4 polarization and improve Aβ clearance in AD models | High-intensity interval training; aerobic exercise; calmodulin inhibitors (trifluoperazine); pharmacological AQP4 modulators | Enhances glymphatic clearance; reduces protein accumulation; improves waste removal | Exercise compliance; pharmacological specificity; avoiding edema | [79,80,81] |
| Complement C1q Inhibition | Blocks initiation of classical complement cascade; prevents C1q tagging of synapses for elimination | C1q deletion or neutralizing antibodies protect synapses and improve cognition in AD mouse models | Anti-C1q monoclonal antibodies; C1q inhibitor peptides; selective C1q blockers | Prevents excessive synaptic pruning; preserves cognitive function; reduces neuroinflammation | Balancing physiological vs. pathological complement; immune surveillance concerns | [19,82,83] |
| Complement C3 Modulation | Prevents C3 cleavage and iC3b-mediated synaptic tagging; blocks complement amplification | C3 deficiency prevents age-related synapse loss and improves LTP in aged mice; protects against AD pathology | C3 inhibitors (compstatin analogs); C3 convertase inhibitors | Reduces synaptic loss; improves cognitive outcomes; maintains neuronal networks | Timing of intervention; systemic complement functions; infection risk | [18,84,85] |
| CR3 (CD11b/CD18) Blockade | Prevents microglial engulfment of iC3b-tagged synapses | CR3 knockout mice protected from Aβ-induced synapse loss; reduced microglial phagocytosis | CR3 antagonists; CD11b-blocking antibodies; small molecule inhibitors | Preserves synapses; reduces microglial-mediated damage; maintains circuit function | Microglial function preservation; specificity for pathological pruning | [19,20] |
| C5aR1 (C5a Receptor) Antagonism | Blocks C5a-mediated microglial activation; reduces excessive synaptic pruning | C5aR1 deletion or PMX205 treatment reduces synapse loss and improves cognition in multiple AD models | PMX205 or PMX53 (C5aR1 antagonists); small molecule C5aR1 inhibitors | Reduces synaptic loss; improves behavior; modulates neuroinflammation without blocking upstream complement | Better therapeutic window than C1q/C3 inhibition; preserves beneficial complement functions | [86,87,88] |
| miR-124 Replacement Therapy | Restores anti-inflammatory signaling; promotes M2 microglial polarization; inhibits inflammatory mediators | miR-124 overexpression reduces neuroinflammation and promotes neuroprotection in injury models | Lipid nanoparticle-encapsulated miR-124; viral vector delivery; synthetic miR-124 mimics | Shifts microglia to anti-inflammatory phenotype; reduces TNF-α; increases IL-10 | Delivery to CNS; off-target effects; stability of miRNA therapeutics | [27] |
| miR-155 Inhibition | Reduces pro-inflammatory signaling; decreases NF-κB activation; attenuates M1 microglial responses | miR-155 deletion improves outcomes in spinal cord injury and reduces neuroinflammation in MS models | AntagomiR-155; locked nucleic acid (LNA) anti-miR-155; GapmeR inhibitors | Reduces neuroinflammation; improves functional recovery; modulates TLR signaling | Delivery challenges; dosing optimization; potential immune effects | [29,89] |
| Meningeal Lymphatic Enhancement | Physical or pharmacological enhancement of mLV structure and function | Exercise enhances mLV flow; VEGF-C expands mLV diameter and improves clearance in aged mice | Aerobic exercise protocols; VEGF-C administration; minimally invasive mLV stimulation | Enhances brain-to-cervical lymph node drainage; improves clearance of proteins and immune cells | Age-related mLV degeneration; non-invasive enhancement methods needed | [30,90] |
| TREM2 Modulation | Regulates microglial phagocytic capacity and metabolic state; modulates complement-mediated pruning | TREM2 deficiency alters microglial response to plaques; affects synaptic engulfment | TREM2 agonistic antibodies; TREM2 activity enhancers (context-dependent) | Modulates microglial function; may enhance beneficial phagocytosis while reducing excessive pruning | Complex role (protective vs. detrimental); stage-dependent effects | [91,92,93] |
| CD200-CD200R Axis Enhancement | Maintains microglial quiescence; promotes M2 polarization; reduces inflammatory activation | CD200-Fc treatment shifts macrophages/microglia from M1 to M2; reduces pro-inflammatory cytokines | CD200-Fc fusion protein; CD200R agonists | Reduces neuroinflammation; promotes neuroprotective microglial phenotype; decreases oxidative stress | Systemic delivery; CNS penetration; long-term safety | [94] |
5.5. Molecular Pathway-Based Therapeutic Targets
5.6. Comparative Therapeutic Efficacy and Intervention Windows
6. Future Directions and Research Priorities
6.1. Current and Planned Clinical Trials
6.2. Neurovascular Unit-Targeted Drug Delivery
6.3. Combination Therapy Approaches
6.4. Translational Challenges and Biomarker Development
7. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Abbreviations
| Aβ | Amyloid-β |
| Akt | Protein Kinase B |
| APOE4 | Apolipoprotein Epsilon 4 |
| AQP4 | Aquaporin-4 |
| ARG-1 | Arginase 1 |
| BBB | Blood–Brain Barrier |
| C/EBPα | CCAAT/Enhancer-Binding Protein alpha |
| C1q | Complement component 1q |
| C3 | Complement component 3 |
| C5aR1 | C5a Receptor 1 |
| CD200-CD200R | CD200-CD200 Receptor |
| CR3 | Complement Receptor 3 |
| CREB1 | cAMP Response Element Binding Protein 1 |
| CSF | Cerebrospinal Fluid |
| ERK | Extracellular signal-Regulated Kinase |
| GFAP | Glial Fibrillary Acidic Protein |
| IL-10 | Interleukin 10 |
| IL-1β | Interleukin 1 beta |
| LPS | Lipopolysaccharide |
| MAPK | Mitogen-Activated Protein Kinase |
| miR-124 | microRNA 124 |
| miR-155 | microRNA 155 |
| NF-κB | Nuclear Factor kappa B |
| PDGF-BB | Platelet-Derived Growth Factor-BB |
| PDGFRβ | Platelet-Derived Growth Factor Receptor-β |
| PI3K | Phosphatidylinositol 3-Kinase |
| PU.1 | PU.1 (also known as SPI1) |
| Qalb | CSF/Plasma Albumin Ratio |
| Ser276 | Serine at position 276 |
| sPDGFRβ | soluble Platelet-Derived Growth Factor Receptor-β |
| TLR | Toll-Like Receptor |
| TNF-α | Tumor Necrosis Factor-α |
| TREM2 | Triggering Receptor Expressed on Myeloid cells 2 |
| VEGF | Vascular Endothelial Growth Factor |
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| Biomarker | Source/Location | Pathophysiological Role | Clinical Significance | Detection Method | Key References |
|---|---|---|---|---|---|
| sPDGFRβ | CSF, released from injured pericytes | Indicates pericyte injury and BBB breakdown; correlates with neuroinflammation | Elevated in early-stage neurodegenerative disorders; correlates with cognitive decline and BBB dysfunction (QAlb) | ELISA, MSD electrochemiluminescence | [12,13,14,15] |
| CSF/Plasma Albumin Ratio (QAlb) | CSF and plasma | Reflects BBB permeability; increased ratio indicates BBB breakdown | Correlates with age, pericyte damage, and neuroinflammation; elevated in MCI and AD | Nephelometry, ELISA | [12,13,16] |
| C1q | Brain tissue, synapses (microglia-derived) | Tags synapses for complement-mediated elimination; initiates classical complement cascade | Increased and localized to synapses before plaque deposition in AD; associated with early synapse loss | Immunohistochemistry, Western blot | [17,18,19] |
| C3/iC3b | Brain tissue, synapses (astrocyte and microglia-derived) | Opsonizes synapses for microglial phagocytosis via CR3 receptor | Elevated in vulnerable brain regions; C3 deficiency protects against age-related synapse loss | Immunohistochemistry, flow cytometry | [18,19,20] |
| AQP4 Polarization Index | Astrocytic perivascular endfeet | Maintains glymphatic fluid flow; loss of polarization impairs waste clearance | Depolarization correlates with disease progression and impaired Aβ clearance | Immunofluorescence microscopy | [21,22,23] |
| CSF YKL-40 | CSF (astrocyte activation marker) | Indicates astrocytic activation and neuroinflammation | Elevated in AD and correlates with BBB dysfunction and PDGFRβ | ELISA | [24,25] |
| CSF GFAP | CSF (astrocyte marker) | Reflects astrocytic reactivity and glial activation | Increased with age and neuroinflammation; associated with BBB dysfunction | ELISA, Simoa | [26] |
| miR-124 | Plasma, CSF, brain tissue | Anti-inflammatory microRNA; maintains microglial quiescence | Downregulated in neurodegeneration; loss promotes M1 microglial polarization | qRT-PCR, sequencing | [27] |
| miR-155 | Plasma, CSF, brain tissue | Pro-inflammatory microRNA; promotes neuroinflammation | Upregulated in MS and AD; correlates with disease severity | qRT-PCR, sequencing | [28,29] |
| VEGF-C | CSF, brain tissue | Regulates meningeal lymphatic vessel function and lymphangiogenesis | Reduced levels associated with impaired brain clearance; therapeutic target | ELISA, Western blot | [30,31] |
| CSF Fibrinogen | CSF (blood-derived) | BBB leakage marker; promotes neuroinflammation | Elevated in AD; correlates with pericyte loss and reduced oxygenation | ELISA, immunohistochemistry | [12] |
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Mansour, G.K.; Bolgova, O.; Hajjar, A.W.; Mavrych, V. Neurovascular Dysfunction and Glymphatic Impairment: An Unexplored Therapeutic Frontier in Neurodegeneration. Int. J. Mol. Sci. 2025, 26, 11843. https://doi.org/10.3390/ijms262411843
Mansour GK, Bolgova O, Hajjar AW, Mavrych V. Neurovascular Dysfunction and Glymphatic Impairment: An Unexplored Therapeutic Frontier in Neurodegeneration. International Journal of Molecular Sciences. 2025; 26(24):11843. https://doi.org/10.3390/ijms262411843
Chicago/Turabian StyleMansour, Ghaith K., Olena Bolgova, Ahmad W. Hajjar, and Volodymyr Mavrych. 2025. "Neurovascular Dysfunction and Glymphatic Impairment: An Unexplored Therapeutic Frontier in Neurodegeneration" International Journal of Molecular Sciences 26, no. 24: 11843. https://doi.org/10.3390/ijms262411843
APA StyleMansour, G. K., Bolgova, O., Hajjar, A. W., & Mavrych, V. (2025). Neurovascular Dysfunction and Glymphatic Impairment: An Unexplored Therapeutic Frontier in Neurodegeneration. International Journal of Molecular Sciences, 26(24), 11843. https://doi.org/10.3390/ijms262411843

