IL-18

Pro-inflammatory cytokine primarily involved in epithelial barrier repair, polarized T-helper 1 (Th1) cell and natural killer (NK) cell immune responses (PubMed:10653850). Upon binding to IL18R1 and IL18RAP, forms a signaling ternary complex which activates NF-kappa-B, triggering synthesis of inflammatory mediators (PubMed:14528293, PubMed:25500532, PubMed:37993714). Synergizes with IL12/interleukin-12 to induce IFNG synthesis from T-helper 1 (Th1) cells and natural killer (NK) cells (PubMed:10653850). Involved in transduction of inflammation downstream of pyroptosis: its mature form is specifically released in the extracellular milieu by passing through the gasdermin-D (GSDMD) pore (PubMed:33883744).

The pro-IL-18 precursor is processed by CASP1, CASP4 or CASP5 to yield its mature, active form (PubMed:15326478, PubMed:25261253, PubMed:37993712, PubMed:37993714, PubMed:9334240). The pro-IL-18 precursor features autoinhibitory interactions between the propeptide and the post-cleavage-site region, preventing recognition by the IL18R1 receptor (PubMed:37993714). Processing by CASP1, CASP4 or CASP5 induces conformational changes to generate critical receptor-binding sites (PubMed:37993714). The mature form is then secreted and released in the extracellular milieu by passing through the gasdermin-D (GSDMD) pore (PubMed:33883744, PubMed:37993714). In contrast, cleavage by CASP3 inactivates IL18 (PubMed:37993714, PubMed:9334240).

Belongs to the IL-1 family.

Isoform 2

Expressed in ovarian carcinoma but undetectable in normal ovarian epithelial cells. Resistant to proteolytic activation by caspase-1 and -4.

• Cytoplasm
• Cytosol
• Secreted
• The precursor is cytosolic (PubMed:33883744). In response to inflammasome-activating signals, cleaved and secreted (PubMed:33883744, PubMed:37993712, PubMed:37993714). Mature form is secreted and released in the extracellular milieu by passing through the gasdermin-D (GSDMD) pore (PubMed:33883744, PubMed:37993714). In contrast, the precursor form is not released, due to the presence of an acidic region that is proteolytically removed by CASP1, CASP4 or CASP5 during maturation (PubMed:33883744, PubMed:37993714). The secretion is dependent on protein unfolding and facilitated by the cargo receptor TMED10 (PubMed:32272059).

IGIF, IL1F4, IL18, Interleukin-18, IL-18, Iboctadekin, Interferon gamma-inducing factor, Interleukin-1 gamma, IFN-gamma-inducing factor, IL-1 gamma

• entrezGene:3606
• omim:600953
• swissprot:Q14116

Proteins

Immunology & Infectious Disease

• Immuno-oncology

22326Da