P-337 A novel senotherapeutic strategy with azithromycin for preventing endometriosis progression

Abstract Study question Could azithromycin (AZM) prevent endometriotic lesion progression by targeting cellular senescence? Summary answer AZM can prevent the progression of endometriotic lesions by inhibiting the secretion of interleukin-6 (IL-6), a senescence-associated secretory phenotype (SASP). What is known already Endometriosis is an estrogen-dependent chronic inflammatory disease. Senescent cells cause chronic inflammation via SASP. Pharmacotherapy targeting senescent cells has garnered attention for various diseases, such as chronic diseases and cancer. Study design, size, duration Nine patients without endometriosis and 22 with endometriosis were recruited for this in vitro study. All samples were obtained from surgical specimens and histologically diagnosed at Nagoya University Hospital between July 2018 and November 2021. This in vivo study involved 12 female BALB/c mice to establish an endometriosis model. Participants/materials, setting, methods Normal endometrial stromal cells (nESCs), endometrial stromal cells with endometriosis (eESCs), and chocolate cyst-derived stromal cells (CSCs) were isolated. To compare cell types, the senescence markers were assessed through morphological features and semi-quantitative immunofluorescence staining (senescence-associated β-galactosidase; SA-β-Gal, p16INK4a and laminB1). The expression of SASP markers was examined in cell culture supernatants using a cytokine array. The effects of senolytic drugs (AZM and navitoclax [ABT263]) on endometriosis were evaluated in vitro and in vivo. Main results and the role of chance CSCs strongly express senescence markers. Semi-quantitative SA-β-Gal and p16INK4a staining intensities were significantly increased, while LaminB1 levels decreased in CSCs compared to those in nESCs and eESCs (SA-b-Gal, P < 0.001; p16INK4a, P < 0.05; LaminB1, P < 0.05). Cytokine array analysis revealed elevated levels of SASP-related cytokines, including IL-6, in CSC supernatants compared with those in nESCs. AZM and ABT263 reduced the viable fraction of CSCs (AZM, P < 0.001; ABT263, P < 0.01). AZM suppressed IL-6 expression in CSC culture supernatants (P < 0.05). In the murine model, AZM administration reduced the endometriotic lesion volume compared to controls (P < 0.05). Proliferative activity, IL-6 expression levels, and fibrosis within endometriotic lesions were also decreased (Ki67, P < 0.01; IL-6, P < 0.001; fibrosis, P < 0.001). Limitations, reasons for caution This study was conducted using a murine model of peritoneal endometriosis, and it was not possible to evaluate the effects of AZM on ovarian function. Further investigation using mouse models of ovarian endometriosis is needed. Wider implications of the findings Our findings suggest that AZM may serve as a potential non-hormonal treatment for endometriosis. A new focus on cellular senescence may reveal novel therapeutic approaches. Trial registration number No