¶ CCL5 — C-C Motif Chemokine Ligand 5
CCL5 (C-C Motif Chemokine Ligand 5), also known as RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted), is a pro-inflammatory chemokine that plays a critical role in immune cell recruitment and neuroinflammation. Originally identified as a T-cell attractant, CCL5 has emerged as a significant mediator in the pathogenesis of Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions[@appay2001].
| Property |
Value |
| Gene Symbol |
CCL5 |
| Gene Name |
C-C Motif Chemokine Ligand 5 |
| Aliases |
RANTES, SIS1, SCYA5 |
| Chromosomal Location |
17q12 |
| NCBI Gene ID |
6352 |
| OMIM |
187011 |
| Ensembl ID |
ENSG00000161570 |
| UniProt ID |
P08246 |
| Associated Diseases |
Alzheimer's Disease, Parkinson's Disease, Multiple Sclerosis, HIV-associated Neurocognitive Disorder |
The CCL5 gene is located on chromosome 17q12 and consists of three exons spanning approximately 8.5 kb. The gene encodes a 91-amino acid secreted protein that is produced as a precursor with a 23-amino acid signal peptide.
CCL5 belongs to the CC chemokine family characterized by two conserved cysteine residues adjacent to the N-terminus:
- N-terminal region — Contains the signal peptide (aa 1-23)
- CC motif — Two conserved cysteines (aa 35-36)
- Core domain — Receptor binding and specificity determining regions
- C-terminal region — Heparin-binding domain for proteoglycan interaction
The mature, secreted CCL5 is a 68-amino acid polypeptide that forms homomers and can also form heteromers with other chemokines.
CCL5 signals through three G protein-coupled receptors[@appay2001]:
- CCR1 — Expressed on monocytes, neutrophils, T cells
- CCR3 — Expressed on eosinophils, Th2 cells
- CCR5 — Expressed on T cells, monocytes, macrophages; major HIV co-receptor
Signal Transduction:
- Gαi-mediated inhibition of adenylate cyclase
- PLCβ activation and IP3/DAG production
- Calcium mobilization
- PI3K/Akt and MAPK pathway activation
- Actin polymerization and chemotaxis
- T cell recruitment — Potent attractant for CD4+ and CD8+ T lymphocytes
- Monocyte recruitment — Facilitates monocyte migration into tissues
- Basophil activation — Induces histamine release
- Eosinophil recruitment — Critical for allergic inflammation
- Memory T cell homing — Guides tissue-specific trafficking
- HIV restriction — Natural CCR5 ligand can block HIV entry
¶ Expression and Regulation
CCL5 is produced by multiple cell types:
- T cells — Especially CD8+ cytotoxic and CD4+ memory T cells
- Macrophages — Pro-inflammatory M1 phenotype
- Platelets — Stored in α-granules
- Fibroblasts — In response to inflammatory signals
- Endothelial cells — Under inflammatory conditions
- Neurons — Particularly in pathological states
CCL5 expression is dynamically regulated:
- Transcriptional — NF-κB, AP-1, STAT1 response elements
- Post-transcriptional — AU-rich elements in 3' UTR affect mRNA stability
- Inducers — TNF-α, IFN-γ, IL-1β, viral infection
- Inhibitors — Glucocorticoids, IL-4, IL-10
In the CNS, CCL5 is expressed by:
CCL5 is significantly implicated in AD pathogenesis[@galimberti2020]:
- Elevated Expression — CCL5 is increased in AD brain tissue, CSF, and plasma
- Aβ Interaction — Amyloid-beta stimulates CCL5 production in glia
- Neuroinflammation — Drives chronic neuroinflammatory response
- T Cell Recruitment — Promotes peripheral immune cell infiltration into brain
- Therapeutic Target — CCL5/CCR5 axis being explored for AD modulation
- Biomarker Potential — CSF CCL5 levels correlate with disease severity
Mechanistic Pathways:
Aβ accumulation → Microglial activation → CCL5 secretion →
T cell recruitment → Chronic inflammation → Neuronal dysfunction
In PD, CCL5 contributes to neuroinflammation[@kho2011]:
- Elevated in SN — Increased CCL5 in substantia nigra of PD brains
- Microglial Activation — CCL5 produced by activated microglia
- Dopaminergic Neurons — May contribute to neuronal death
- T Cell Involvement — Peripheral T cells recruited to PD brain
- Therapeutic Implications — CCR5 antagonists under investigation
- Demyelination — CCL5 promotes inflammatory demyelination
- Lesion Formation — High CCL5 in MS plaques
- Therapeutic Target — CCR5 antagonists explored in MS models
¶ HIV-Associated Neurocognitive Disorder (HAND)
- Viral Infection — HIV induces CCL5 expression in brain
- Neuroinflammation — Contributes to HIV-induced neurotoxicity
- CCR5 Role — HIV uses CCR5 as entry co-receptor
¶ Stroke and Brain Injury
- Ischemic Injury — CCL5 upregulated in response to stroke
- Reperfusion Damage — Contributes to secondary injury
- Therapeutic Potential — CCR5 blockade may reduce damage
Targeting the CCL5/CCR5 axis:
- Maraviroc — CCR5 antagonist approved for HIV, being explored for neurodegeneration
- Vicriviroc — CCR5 antagonist in clinical trials for various indications
- CCR5 Knockdown — Gene therapy approaches under development
- HIV-related trials with CCR5 antagonists have shown CNS penetration
- Ongoing studies in AD and MS using CCR5 modulators
- CSF CCL5 as marker of neuroinflammation
- Plasma CCL5 as peripheral biomarker
- Correlation with disease progression
- CCL5 Knockout Mice — Viable with altered immune responses
- Transgenic Overexpressors — CCL5 overexpression models
- AAV-mediated Delivery — Viral vector delivery for CNS expression
- ELISA — Quantify protein levels in tissues and fluids
- qPCR — Measure mRNA expression
- Immunohistochemistry — Localization in brain tissue
- Flow Cytometry — Surface CCR5 measurement
- Appay V, Rowland-Jones SL, RANTES: a chemokine with multiple roles (2001)
- Galimberti D et al, CCL5 in Alzheimer's disease: a novel biomarker and therapeutic target (2020)
- McGeer PL, McGeer EG, The inflammatory response system of brain: implications for therapy of Alzheimer and Parkinson disease (1999)
- Kho DS et al, Chemokines and their receptors in Parkinson's disease (2011)