Interleukin-4 suppresses TIMP-2 transcription during endometriosis: Allele-specific regulation of the TIMP-2 -418G/C promoter by SP1

Abstract Tissue inhibitor of metalloproteinase-2 (TIMP-2) is a critical regulator of extracellular matrix (ECM) homeostasis in inflammatory disorder, but the mechanisms underlying its dysregulation in endometriosis remain poorly understood. Furthermore, whether inflammatory cytokine signaling and functional genetic variants within the TIMP-2 promoter contribute to its altered expression during disease progression is unknown. This study investigated the regulation of TIMP-2 expression by interleukin-4 (IL-4) signaling and the functional significance of the TIMP-2 -418G/C promoter polymorphism in endometriosis. We found that TIMP-2 expression was significantly reduced in ectopic lesions and serum samples from endometriosis patients in comparison to normal. Functional promoter analyses revealed that the -418C allele exhibited higher basal transcriptional activity than the G allele while displayed greater sensitivity to IL-4-mediated repression. IL-4 activated STAT6 signaling concomitant with SP1 and TIMP-2 downregulation, whereas SP1 overexpression restored TIMP-2 expression and SP1 silencing further suppressed its transcription, identifying SP1 as a positive regulator of TIMP-2. Single-cell transcriptomic analyses identified fibroblasts and mesenchymal populations as the major TIMP-2-expressing cell types and revealed enhanced inflammatory signaling and ECM remodeling networks in endometriosis. Collectively, these findings identify an IL-4-SP1-TIMP-2 regulatory axis that contributes to aberrant ECM turnover in endometriosis. Furthermore, the TIMP-2 -418G/C promoter polymorphism influences cytokine-mediated transcriptional regulation of TIMP-2, providing new mechanistic insights into the interplay between inflammatory signaling, genetic variation, and ECM homeostasis during endometriosis progression.