| IL30 — Interleukin 30 (p28) | |
|---|---|
| Symbol | IL30 |
| Full Name | Interleukin 30 (IL-27 p28 subunit) |
| Chromosome | 1p13.1 |
| NCBI Gene ID | 359710 |
| Protein Class | Cytokine (IL-12 family member) |
| UniProt | Q8TD97 |
| Alias | IL27, p28, IL-27A |
| Expression | Immune cells, CNS [microglia](/cell-types/microglia-neuroinflammation), [astrocytes](/entities/astrocytes) |
IL30 (Interleukin 30), also known as IL-27p28 or simply p28, is the α-chain subunit of the heterodimeric cytokine IL-27. Initially characterized as an IL-27-specific subunit, IL30 can be secreted independently of its partner molecule EBI3 (Epstein-Barr virus-induced gene 3), functioning both as a component of IL-27 and as a standalone cytokine with distinct biological activities. Located on chromosome 1p13.1, this gene encodes a secreted glycoprotein that plays critical roles in immune regulation, particularly in the context of neuroinflammation, autoimmunity, and potentially neurodegenerative diseases.
The IL-30 protein represents an important member of the IL-12 cytokine family, which also includes IL-12 (p35/p40), IL-23 (p19/p40), and IL-35 (p35/EBI3). Each heterodimeric cytokine in this family has distinct immunological functions, with IL-27/IL-30 occupying a unique position at the interface between innate and adaptive immunity.
The IL30 gene (NCBI Gene ID: 359710) spans approximately 7.5 kb and consists of 5 exons. The encoded protein contains a signal peptide at the N-terminus that directs secretion, followed by a four-helix bundle cytokine domain characteristic of the IL-12 family. Alternative splicing generates multiple transcript variants, though the canonical form encodes a 241-amino acid secreted protein with a molecular weight of approximately 27 kDa.
IL30 can exist in multiple forms:
IL-27 Heterodimer: IL30 forms a disulfide-bonded heterodimer with EBI3 (IL-27B), creating the mature IL-27 cytokine. The crystal structure reveals that this heterodimer resembles a "pocket" shape, with IL30 contributing the central beta-sheet and EBI3 forming the sides.
IL-30 Monomer: IL30 can be secreted independently, particularly by certain activated immune cells. This monomeric form has distinct biological activities that differ from the IL-27 heterodimer.
IL-30 Homodimer: Some evidence suggests IL30 can form homodimers, though the functional significance remains under investigation.
IL-27 (IL30+EBI3) signals through a heterodimeric receptor composed of:
Signaling through this receptor complex activates the JAK-STAT pathway, particularly STAT1 and STAT3, leading to downstream transcriptional regulation.
Notably, IL30 alone (without EBI3) may signal through alternate receptors or present different binding kinetics, explaining its distinct functional profile.
IL30 is expressed by multiple immune cell populations:
Expression is typically induced by:
Within the CNS, IL30 is expressed by:
The CNS expression of IL30 places it in a prime position to modulate neuroinflammatory processes relevant to neurodegenerative diseases.
IL-30/IL-27 exhibits a complex, context-dependent immunoregulatory profile:
Pro-inflammatory Effects:
Anti-inflammatory Effects:
This dual nature means IL-30 can either promote or suppress inflammation depending on the cellular context, disease stage, and cytokine milieu.
Multiple Sclerosis and EAE
IL-30 has been extensively studied in the context of multiple sclerosis (MS) and its mouse model, experimental autoimmune encephalomyelitis (EAE):
The complexity is illustrated by studies showing that while systemic recombinant IL-30 exacerbates EAE, local CNS expression may be protective—a paradox requiring further investigation.
Rheumatoid Arthritis
IL-30 levels are elevated in rheumatoid arthritis synovial fluid, where it may contribute to joint inflammation through effects on T cells and fibroblasts.
In infection settings, IL-30/IL-27:
While direct evidence for IL30 involvement in AD remains limited, several mechanistic links suggest potential relevance:
Neuroinflammation: AD is characterized by chronic neuroinflammation, with microglial activation contributing to disease progression. IL30 modulates microglial function and could influence the neuroinflammatory milieu.
IL-10 Induction: IL-30's potent ability to induce anti-inflammatory IL-10 could theoretically suppress harmful neuroinflammation, though this remains theoretical in AD context.
Aging Effects: Aging increases neuroinflammation. Given IL30's role in modulating age-related immune changes, it may influence neurodegeneration through immunosenescence pathways.
Therapeutic Targeting: The IL-27/IL-30 pathway has been proposed as a therapeutic target in AD, though direct evidence is lacking.
Similarly, IL30 connections to PD are indirect but mechanistically plausible:
Microglial Activation: PD involves microglial activation in the substantia nigra. IL30 modulates microglial phenotype and could influence dopaminergic neuron survival.
Neuroinflammation: As in AD, chronic neuroinflammation contributes to PD pathogenesis. IL-30's immunomodulatory properties could theoretically modify this process.
Alpha-synuclein Pathology: Some evidence links cytokine pathways to alpha-synuclein aggregation and spread; IL-30 could potentially influence these mechanisms.
ALS shows connections to IL-30/IL-27 signaling:
The strongest case exists for IL30 in MS:
While IL30 forms the heterodimeric IL-27 cytokine with EBI3, monomeric IL-30 has distinct functions:
| Property | IL-27 (IL30+EBI3) | IL-30 (Monomer) |
|---|---|---|
| Receptor | IL27RA + GP130 | May differ |
| STAT Activation | STAT1, STAT3 | Primarily STAT3 |
| Primary Effect | Th1 promotion | Immunosuppression |
| IL-10 Induction | Strong | Variable |
IL-30 shares the GP130 receptor subunit with IL-6, IL-11, LIF, OSM, and CNTF. This creates potential for:
The IL-30/IL-27 pathway represents a compelling therapeutic target for several reasons:
Agonists:
Antagonists:
The IL-27/IL-30 pathway has been targeted in:
Translation to neurodegenerative disease treatment remains an active area of investigation.
Multiple SNPs in the IL30 gene have been associated with:
These genetic associations underscore the functional importance of IL-30 in immune regulation.
IL30 expression is subject to epigenetic control:
IL-30 and IL-27 levels in:
These can serve as biomarkers of disease activity and treatment response.