The Possible Protective Effects of leuprolide against Cyclophosphamide-Induced ovarian toxicity Via Modulation of the Cgas-STING Pathway in Rats.

Abstract

Premature Ovarian Insufficiency (POI) is defined as a premature loss of ovarian activity that results in low levels of estrogen, loss of follicles and infertility before age 40. The potent chemotherapeutic agent cyclophosphamide (CTX) causes significant gonadotoxic effects and early onset of follicular atresia. Recent discoveries suggest that the cyclic GMP-AMP synthase (cGAS)–stimulator of interferon genes (STING) pathway is an innate immune sensor of cytosolic double-stranded DNA (dsDNA) and is implicated in downstream inflammation and cellular injury during DNA damage.
Objective: This study aimed to assess the protective effect of Leuprolide acetate (GnRH agonist) in ovarian toxicity induced by CTX through modulating inflammation by the cGAS-STING pathway, and compare its results with the specific STING inhibitor, H-151.
Materials and Methods: Forty eight adult female Albino rats (6-8 weeks old) were divided into six different experimental groups (n=8 per group): Control, Cyclophosphamide , Leuprolide protective , Leuprolide with cyclophosphamide , STING Inhibitor group , and H-151 + Cyclophosphamide . Anti-Müllerian Hormone (AMH) and Autophagy progression was evaluated by the quantification of the hormone using ELISA. RT-qPCR was used to measure the gene expression of the downstream nuclear factor-kappa B (NF-κB). Immunohistochemical scoring and light microscopy were used to assess apoptotic indexes (Caspase and Bcl-2), and to determine the histopathological architectural changes.
Results: AMH reserve markers were significantly reduced (33.49±5.93) and cell stress mediated LC3B autophagy markers were significantly elevated (6.53±1.28), alongside with enhanced levels of apoptosis markers (Caspase score: 8, Bcl-2 score: 2) after CTX induction. The co-treatment with Leuprolide or H-151 before CTX induction significantly maintained high AMH reserves (74.20±11.84), and restored the baseline expression of homeostatic LC3B (1.39±0.25). In addition, combination therapies limited the fold change in NF-κB downstream of the fold, reduced the level of apoptotic signal through the activation of Caspase and maintained primary/secondary follicular morphometrics.
Conclusion: pre-Treatment with Leuprolide is protective against ovarian collapse induced by chemotherapy. This preservation is due to the inhibition of downstream cGAS-STING signalling pathway, which fails to cause chronic inflammatory damage and preserve normal follicular architecture.