sST2

sST2, or soluble suppression of tumorigenicity 2, is the soluble isoform of the ST2 receptor, part of the interleukin-1 receptor family. The ST2 gene (IL1RL1) yields two main isoforms by alternative splicing: a transmembrane form (ST2L) and a soluble form (sST2). sST2 circulates in the blood and functions primarily as a decoy receptor for interleukin-33 (IL-33), binding IL-33 and preventing signaling through ST2L on target cells.

Physiology and pathophysiology: IL-33/ST2 signaling is involved in cardiac and inflammatory responses. Mechanical stress and tissue injury promote IL-33 release; sST2 rises in response to myocardial stress and systemic inflammation. By sequestering IL-33, elevated sST2 can blunt protective IL-33/ST2L signaling, which is associated with adverse cardiac remodeling and progression of heart failure.

Clinical relevance: sST2 is used as a biomarker in cardiovascular disease, especially for prognosis in heart failure and acute coronary syndromes. Higher baseline and rising sST2 levels correlate with increased mortality and hospitalization risk, providing information that complements natriuretic peptides. It is not a diagnostic test for heart failure but a prognostic tool and may aid in risk stratification and treatment decisions in some settings. Levels are measured in serum or plasma with immunoassays such as ELISA; cutoff values depend on the assay. Levels may be influenced by non-cardiac factors and renal function.

See also: Related topics include IL-1 receptor family member IL1RL1, its ligand IL-33, and the membrane receptor ST2L.