Il18Bp Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
The IL18BP Gene encodes interleukin-18 binding protein (IL-18BP), a soluble protein that acts as a natural inhibitor of interleukin-18 (IL-18), a pro-inflammatory cytokine involved in the innate immune response. IL-18BP binds IL-18 with high affinity, preventing its interaction with the IL-18 receptor and thereby neutralizing its biological activity. This gene is critically involved in regulating inflammatory responses and has emerged as a therapeutic target in various neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD).
| IL18BP - Interleukin 18 Binding Protein |
|---|
| Full Name | Interleukin 18 Binding Protein |
| Chromosome | 11p15 |
| NCBI Gene ID | 10004 |
| OMIM ID | 604514 |
| Ensembl ID | ENSG00000147421 |
| UniProt ID | O95298 |
| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, Inflammatory Disorders, Autoimmune Diseases, Stroke |
¶ Protein Structure and Function
IL-18BP is a secreted protein belonging to the immunoglobulin superfamily, despite lacking a transmembrane domain. The protein consists of a single immunoglobulin-like domain that enables high-affinity binding to IL-18[1].
- Immunoglobulin-like domain: Single V-type Ig domain (~100 amino acids)
- Molecular weight: Approximately 40 kDa
- Secretion: Constitutively secreted by various cell types
- No transmembrane region: Functions as a soluble receptor decoy
IL-18BP neutralizes IL-18 through a high-affinity interaction:
- Binding affinity: IL-18BP binds mature IL-18 with dissociation constant (Kd) of approximately 0.4 nM[2]
- Receptor blockade: Prevents IL-18 from engaging the IL-18 receptor α-chain (IL-18R1)
- Signal inhibition: Blocks downstream activation of NF-κB and MAPK signaling pathways
- IFN-γ suppression: Neutralizes IL-18's ability to induce interferon-γ (IFN-γ) production in T cells and natural killer (NK) cells
The IL18BP gene generates multiple splice variants:
- IL-18BPa: The major isoform with potent IL-18 neutralizing activity
- IL-18BPb: A less abundant isoform with reduced neutralizing capacity
- Additional alternatively spliced variants have been identified with tissue-specific expression patterns
IL-18BP expression is tightly regulated by inflammatory mediators:
- Induced by: Interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β)[3]
- Feedback mechanism: Provides negative feedback to limit excessive IL-18-driven inflammation
- Dysregulation: Altered expression is associated with chronic inflammatory conditions
In Alzheimer's disease, IL-18BP plays a complex role in modulating neuroinflammation:
- Counter-regulatory function: IL-18BP acts to neutralize neurotoxic IL-18, which is elevated in AD brain tissue and cerebrospinal fluid[4]
- Decreased expression: Studies have shown decreased IL-18BP levels in AD brain tissue compared to healthy controls, creating an imbalance that promotes chronic inflammation[5]
- Therapeutic potential: Recombinant IL-18BP (tadekinig alfa) has been explored as a therapeutic agent to dampen IL-18-driven neuroinflammation in AD
- Amyloid relationship: IL-18 may interact with amyloid-beta pathology to amplify microglial activation and neuronal damage
In Parkinson's disease, IL-18BP may provide neuroprotective effects:
- Dopaminergic neuron protection: IL-18BP may protect dopaminergic neurons in the substantia nigra from IL-18-mediated toxicity[6]
- Genetic variants: Certain polymorphisms in the IL18BP gene have been associated with altered PD risk in genome-wide association studies (GWAS)[7]
- Therapeutic targeting: Enhancing IL-18BP activity represents a potential strategy to mitigate neuroinflammation in PD
¶ Stroke and Cerebral Ischemia
Following ischemic stroke, IL-18BP has been studied for its neuroprotective potential:
- Acute phase response: IL-18 levels increase dramatically following cerebral ischemia
- IL-18BP administration: Exogenous IL-18BP has shown neuroprotective effects in experimental stroke models
- Clinical implications: The IL-18/IL-18BP balance may influence stroke outcomes
Emerging evidence suggests IL-18BP involvement in ALS pathophysiology:
- Motor neuron inflammation: IL-18 contributes to inflammatory processes affecting motor neurons
- Therapeutic exploration: Modulating the IL-18 pathway through IL-18BP represents a potential therapeutic approach
IL-18BP is expressed in various tissues throughout the body, with distinct patterns in the brain:
| Cell Type |
Expression Level |
Regulation |
| Neurons |
Moderate |
Constitutive, inducible |
| Astrocytes |
Low-Moderate |
Highly inducible by IFN-γ |
| Microglia |
Low |
Inducible by inflammatory signals |
| Oligodendrocytes |
Low |
Limited data |
- Monocytes/macrophages: Strongly inducible by IFN-γ
- Dendritic cells: Constitutively expressed at moderate levels
- Epithelial cells: Inducible in various tissues
- Endothelial cells: Expression modulated by cytokines
- Mechanism: Administered IL-18BP neutralizes excess IL-18
- Clinical development: Originally developed for inflammatory and autoimmune conditions
- Neurodegeneration potential: Being explored for AD, PD, and other neuroinflammatory conditions
- Recombinant protein therapy: Direct administration of IL-18BP
- Gene therapy: Viral vector-mediated IL18BP expression
- Small molecule modulators: Compounds that upregulate endogenous IL-18BP
- Combination approaches: IL-18BP with other anti-inflammatory agents
- Blood-brain barrier penetration
- Optimal dosing regimens
- Patient selection based on IL-18/IL-18BP imbalance
- Long-term safety considerations
flowchart TD
subgraph IL18_Signaling
IL18[IL-18 Cytokine] -->|binds| IL18R1[IL-18R1/IL-18R Acceptor] -->
IL18R1 -->|recruits| MyD88[MyD88 Adaptor] -->
MyD88 -->|activates| NFKB[NF-κB Pathway] -->
MyD88 -->|activates| MAPK[MAPK Pathway] -->
NFKB -->|induces| INFG[IFN-γ Production] -->
MAPK -->|activates| AP1[AP-1 Transcription] -->
INFG -->|promotes| TH1[Th1 Differentiation] -->
TH1 -->| усиливает | INFL[Inflammatory Response]
end
subgraph IL18BP_Inhibition
IL18BP[IL-18BP] -->|sequesters| IL18
IL18 -->|blocked| X[No Signaling]
end
- IL-1β pathway: Shares downstream signaling components with IL-18
- NLRP3 inflammasome: IL-18 is activated by NLRP3; IL-18BP can modulate this axis
- NF-κB network: Central hub for IL-18-mediated inflammatory transcription
- Novick D, et al. (1999). "Interleukin-18 binding protein: a novel modulator of the Th1 cytokine response". Immunity. 10:127-136. PMID:10072537[1]
- Kim SH, et al. (2000). "Structural requirements of six naturally occurring isoforms of the IL-18 binding protein to neutralize IL-18". J Clin Invest. 105:173-181. PMID:10642596[2]
- Burek C, et al. (2019). "Interleukin-18 in the CNS". J Neuroinflammation. 16:106. PMID:31133031[3]
- Ojala J, et al. (2012). "Interleukin-18 and its binding protein in Alzheimer's disease". J Alzheimers Dis. 31:371-381. PMID:22543851[4]
- Bossù P, et al. (2010). "Interleukin-18 involved in Alzheimer's disease: a potential therapeutic target?". Curr Alzheimer Res. 7:265-270. PMID:20082803[5]
- Sugama S, et al. (2005). "IL-18 in Parkinson's disease". J Neural Transm Suppl. 273-278. PMID:15917545[6]
- Chang D, et al. (2018). "IL18BP is a novel Parkinson's disease risk locus". Nat Genet. 50:1682-1687. PMID:30482948[7]
- Girardelli M, et al. (2020). "IL-18/IL-18BP imbalance in neuroinflammation". Front Immunol. 11:598764. PMID:33362765[8]
The study of Il18Bp Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Novick D, et al. (1999). Interleukin-18 binding protein: a novel modulator of the Th1 cytokine response. Immunity. 10:127-136. PMID:10072537
- Kim SH, et al. (2000). Structural requirements of six naturally occurring isoforms of the IL-18 binding protein to neutralize IL-18. J Clin Invest. 105:173-181. PMID:10642596
- Burek C, et al. (2019). Interleukin-18 in the CNS. J Neuroinflammation. 16:106. PMID:31133031
- Ojala J, et al. (2012). Interleukin-18 and its binding protein in Alzheimer's disease. J Alzheimers Dis. 31:371-381. PMID:22543851
- Bossù P, et al. (2010). Interleukin-18 involved in Alzheimer's disease: a potential therapeutic target? Curr Alzheimer Res. 7:265-270. PMID:20082803
- Sugama S, et al. (2005). IL-18 in Parkinson's disease. J Neural Transm Suppl. 273-278. PMID:15917545
- Chang D, et al. (2018). IL18BP is a novel Parkinson's disease risk locus. Nat Genet. 50:1682-1687. PMID:30482948
- Girardelli M, et al. (2020). IL-18/IL-18BP imbalance in neuroinflammation. Front Immunol. 11:598764. PMID:33362765