The Levonorgestrel Intrauterine System Attenuates the Expression of Angiopoietin-1, Angiopoietin-2, and Vascular Endothelial Growth Factor in Adenomyosis

Abstract

Background/Objectives: Adenomyosis is characterized by aberrant endometrial invasion and heavy menstrual bleeding, with angiogenesis being implicated as a key mechanism of this condition. We compared vascular endothelial growth factor (VEGF), angiopoietin-1 (ANGPT-1), and angiopoietin-2 (ANGPT-2) expression in eutopic and ectopic endometria from patients with adenomyosis and evaluated whether the levonorgestrel intrauterine system (LNG-IUS) modulates these angiogenic markers. Methods: In a case-control analysis, specimens from patients with adenomyosis without an LNG-IUS (n = 20), those with adenomyosis with prior LNG-IUS insertion (n = 18), and controls (n = 12) were analyzed. Immunohistochemistry with H-scores was used to assess protein expression in eutopic and ectopic tissues. ANGPT1, ANGPT2, and VEGFA mRNA in eutopic endometrial tissue were quantified by qRT-PCR. Results: In untreated adenomyosis patients, ectopic endometria showed higher protein expression than eutopic tissue for ANGPT-1, ANGPT-2, and VEGF (all p <= 0.05). The LNG-IUS was associated with significantly lower expression of all three markers in both eutopic and ectopic tissue (all p < 0.01), with eutopic levels approaching those of controls. qRT-PCR findings corroborated the decrease in ANGPT1, ANGPT2, and VEGFA transcript levels after LNG-IUS insertion (all p < 0.05). Conclusions: Adenomyosis is characterized by upregulated angiogenic signaling in both eutopic and ectopic endometria. The LNG-IUS attenuates ANGPT-1, ANGPT-2, and VEGF expression at both the protein and transcript levels, suggesting that modulation of angiogenic pathways may contribute to its therapeutic benefit in abnormal uterine bleeding associated with adenomyosis.