The fertility of women declines sharply after age 35 and is essentially lost upon menopause at age 51. The ovary plays an important part in aging-associated changes in women’s physiology since it is an essential component of both the reproductive and endocrine systems. Several previous studies in mice have shown that the ovarian tissue goes through drastic changes over the course of aging and exhibits signs of aging-associated chronic inflammation (inflammaging), which may contribute to the marked decline of oocyte quality in aged individuals. To further examine aging-associated gene expression changes in the ovary and to characterize the development of inflammaging, we performed detailed transcriptomic analysis of whole ovaries from mice of six different age groups over the mouse reproductive lifespan and identified more than 5000 genes with significant expression change over the course of aging. Intriguingly, we found aging-associated changes in the expression of several markers that indicate alterations in the composition of ovarian macrophages, which are known to be central players of inflammaging. Using flow cytometry, we analyzed and compared macrophage populations and polarization in young and old ovaries and found a significant increase in monocyte recruitment and macrophage alternative activation (M2) in the old ovaries compared to those in young. Our results are consistent with previous findings of aging-associated increase of fibrosis in the ovarian stromal extracellular matrix, and they provide new clues about the development of inflammaging in the mammalian ovary.

Parotid glands are treated clinically as though the distribution of functional burden were homogeneous. Radiotherapy treatments are planned using whole parotid mean dose to predict risk of salivary dysfunction. Recent progress has identified specific parotid non-homogeneities by demonstrating the existence of regional, bath-and-shower, and dose-volume effects. In this work, parotid regional effects and their impact on salivary function are quantified using a nonparametric (model-free) approach. Regional effects have implications for clinical sparing practices. Radiotherapy planning contours, dose profiles, and late clinical outcomes from a single cohort consisting of N = 332 patients was used. Pre-radiotherapy and one year post-radiotherapy whole mouth stimulated saliva were collected for assessment of salivary dysfunction. Organ-at-risk parotid glands were segmented into 2, 3, 4, 18, and 96 equal-volume sub-segments. Sub-segment relative importance was derived from mean dose regressors using random forests and conditional inference trees. Regressor multicollinearity, cohort homogeneity, and overfitting were addressed. Linear and exponential whole parotid mean dose models were also implemented for comparison purposes. Exclusion of caudal-anterior sub-segments negatively impacted prediction the most. The most important sub-segments had importances 2.4× (on average over all segmentation methods) or >4× (at the finest level of segmentation) that of an equivalent sub-segment in a theoretical homogeneous parotid. In contrast, the least important sub-segments held virtually no importance for prediction. Both random forests and conditional inference trees outperformed parametric (model-based) techniques. Both improved prediction as segmentation was refined. Radiation dose to caudalanterior aspects of the parotid are the strongest predictors of radiotherapy-induced late stimulated whole mouth saliva, and are thus the most clinically-relevant regions for controlling dysfunction. Cranial and posterior aspects are less important. Shifting dose from regions of high importance to low importance may therefore improve patient outcomes.

Multidrug resistance transporters (MDRs) are best known for their pathological role in neoplastic evasion of chemotherapeutics and antibiotics. Here we show that MDR-1 is present in the oocyte mitochondrial membrane, and it protects the female gamete from oxidative stress. Female mdr1a mutant mice have no significant difference in ovarian follicular counts and stages, nor in reproductively functioning hormone levels, yet these mice are significantly more vulnerable to gonadotoxic chemotherapy, have chronically elevated reactive oxygen species in immature germinal vesicle oocytes, exhibit a significant over-accumulation of metabolites involved in the tricarboxylic acid cycle (TCA), and have abnormal mitochondrial membrane potential. The mdr1a mutant ovaries have a dramatically different transcriptomic profile with upregulation of genes involved in metabolism. Our findings indicate that functionality of MDR-1 reveals a critical intersection of metabolite regulation, oxidative stress, and mitochondrial dysfunction that has direct implications for human infertility, premature reproductive aging due to oxidative stress, and gonadoprotection.