Purpose: Interleukin (IL)-1A C-889T, IL-1B C-511T, IL-1B C-31T, IL-1B C3954T, and IL-1RN 86-bp VNTR (variable number of tandem repeats) are polymorphisms potentially influencing IL-1 beta production. This review summarizes 1) the biological roles of IL-1 beta, 2) allele frequencies of the polymorphisms, and 3) the reported associations between these polymorphisms and disease risk.
Methods: Papers were obtained from PubMed with keywords "IL-1, polymorphism", as well as from the references in each paper. The most relevant papers were then selected. In this review, a narrative approach was adopted.
Results: IL-1 beta is a multifunctional proinflammatory cytokine, whose signal is transduced through IL-1 receptor I (IL-1RI) on the cell surface. Binding levels are influenced by the IL-1 receptor antagonist (IL-1Ra), IL-1RII (decoy receptor with no signal transduction), soluble IL-1RI, and soluble IL-1RII. IL-1B encoding IL-1 beta is located on chromosome 2q14, along with IL-1A encoding IL-1 alpha and IL-1RN encoding IL-1Ra. The minor alleles, IL-1A-889T, IL-1B 3954T, and IL-1RN 2R, are rarer in Japanese than in Caucasians, while IL-1B-511T and IL-1B-31C are more frequent. These polymorphisms have been reported to have potential associations with the risk of diseases, such as stomach cancer, breast cancer, inflammatory bowel, Alzheimer's, and osteoporosis.
Discussion: Although there are many inconsistent findings on associations with the polymorphisms, IL-1B C-511T and the tightly linked T-31C may be useful for predicting the risk of diseases with an inflammation basis among Japanese.