The following is the summary of “Role of apoptosis and autophagy in ovarian follicle pool decline in children and women diagnosed with benign or malignant extra-ovarian conditions” published in the January 2023 issue of Human reproduction by Cacciottola, et al.

Which biological mechanisms underlie the age-related loss in a woman’s ovarian reserve and the pathological depletion of follicles caused by inflammation or a pro-oxidant environment? Autophagy plays a crucial part in the physiological reduction of the ovarian follicle pool in prepubescent girls, while apoptosis is responsible for the age-related drop and increases in the event of past chemotherapy in children. Follicle loss has been linked to apoptosis and autophagy, two forms of programmed cell death. While the role of apoptosis in the elimination of damaged follicles, such as those compromised by chemotherapy (CHT), is well established, its role in the physiological age-related reduction of follicles is less clear. While autophagy has been shown to play a critical role in the maintenance of follicle quiescence in murine models, its role in the control of follicle pools in humans remains unclear.

At the time of cryopreservation (between 2012 and 2021) at a tertiary care hospital, ovarian tissue from 84 individuals with benign or malignant extra-ovarian diseases was kept for histological studies. Hematoxylin and eosin staining was used to count and categorize follicles; cleaved caspase-3 immunostaining was used to identify follicle apoptosis; and microtubule-associated proteins 1A/1B light chain 3B immunolabeling was used to detect follicle autophagy, all using ovarian fragments. Oocytes and granulosa cells’ ultrastructural characteristics were also examined using transmission electron microscopy. Age, menstrual state (premenarchal=32; postmenarchal=52), potentially gonadotoxic CHT before cryopreservation (n = 14), endometriosis, and hormone treatment were also considered in all analyses. Total follicle density was higher in premenarchal individuals [mean, range 4979.98 (342.2-21789) versus 918.8 (26.18-3983), P<0.001] but there were more morphologically aberrant follicles (8.52 (0-25.37)% versus 3.54 (0-17.5%)%, P<0.001] and atretic follicles (15.8 (031.85)% versus 10. While apoptosis rates remained constant with age [27.94 (0-93.2)% in prepubertal subjects and 29.5 (0-100)% in postpubertal subjects], autophagic follicles were roughly 10 times more common in premenarchal than postmenarchal subjects [10.21 (0-62.3)% versus 1.34 (0-25)%, P<0.001]. These follicles play a crucial role in the age-related decline and elimination of ‘ The effects of a CHT diagnosis and history varied with age. More apoptotic follicles (40.22% vs. 26.79%, P<0.05) and fewer abnormal follicles (3.84 vs. 9.83, P<0.01) were found in premenarchal patients who had undergone CHT prior to ovarian tissue cryopreservation, indicating a direct effect on follicle elimination, particularly of those with abnormalities. Quiescent follicle rates were lower in postmenopausal women with a history of CHT compared to patients without a history of CHT before tissue freezing [71.57 (0-100)% versus 85.89 (50-100)%, P<0.05]. This finding suggests that follicle activation and growth are expedited in these patients. Furthermore, post-adolescent cancer diagnoses were associated with elevated autophagic activity [26.27 (0-100)% versus 9.48 (0-29.41)%, respectively, P<0.05] compared to post-adolescent benign diagnoses. 

Patients who had previously had CHT constituted a highly varied population, making it impossible to study the effect of different CHT regimens. This investigation expands their knowledge of the mechanisms that control follicular pool decrease by demonstrating, for the first time, the roles played by the apoptosis and autophagy pathways in physiological follicle depletion, the latter of which is particularly important prior to puberty. In addition, we found that the oocytes of premenarchal participants with a history of CHT had a greater apoptosis rate in response to non-physiological damage, confirming that this pathway is activated by medications known to generate DNA damage in oocytes, such as alkylating agents, but not by cancer itself. Grants from the Fondation contre le Cancer (grant 2018-042 awarded to A.Ca. ), the Fondazione Comunitaria del Varesotto and Provincia di Varese (‘Amalia Griffini’ Fellowship in Gynecology and Obstetrics awarded to A.Ce. ), the Fonds Spécialiux de Recherche, the Fondation St Luc, and donnatio ad benevolenti helped fund this study. Authors have no conflicts of interest to disclose.

Source: academic.oup.com/humrep/article-abstract/38/1/75/6809920?redirectedFrom=fulltext