Biomarkers of ovarian ageing

The ovary is the main regulator of female fertility, and its biologic clock is set to ensure reproductive success during a definite life stage. According to the evolutionary concept that organisms maximize fitness by promoting production of progeny, allocation of resources between reproductive and somatic functions is finely regulated during life. Thus, it has been speculated that the premature ageing of the ovary when compared with somatic organs might result from increased energy demand for maintenance and repair processes in the soma compartment during ageing. According to the human biologic clock, the gradual loss of female fertility becomes more dramatic in the late 30s with a steep decrease beginning after age 35, ending in menopause at mean age of 51 years. This would preserve women from the physical stress of pregnancy in advanced age and maximize the length of time they can bear children. As a result, increasing postponement of the first pregnancy represents a crucial factor in the widespread of subfertility in industrialized societies. Given the intrapopulation variability of the reproductive life span, it is generally accepted that coping with this issue requires a careful reproductive counselling based on accurate predictive markers. Ovarian functional decline with ageing has been so far extensively characterized in terms of gradual depletion of ovarian follicles and reduced ability to produce oocytes competent for fertilization and further development. The analysis of the molecular and cellular aspects of follicle ageing would require careful consideration. In fact, oocytes and granulosa cells of primordial follicles might remain in ‘resting’ phase for a long time, thus behaving as post-mitotic cells which can be required to start growing after 10–50 years. Furthermore, both primordial and growing follicles become exposed to environmental factors related to the ageing of the ovarian somatic compartment, and finally, the development of a competent oocyte intimately depends on the crosstalk between all compartments in the ovary. For decades, research on reproductive ageing has been focusing on the so-called quantitative aspect of ovarian ageing, which has led to mathematical models predicting follicle loss on the basis of chronologic age without taking into account biologic markers. When the concept of oocyte ageing as the main determinant of fertility decline has become clear, researchers have begun to expand investigations into the whole ovarian microenvironment in search of age-related changes with potential effects on follicle and oocyte competence. Although it is generally accepted that ageing is a result of both inborn and environmental factors, most of the numerous theories of ageing share the concept that age-associated malfunction results from physiological accumulation of irreparable damage to biomolecules as an unavoidable side effect of normal metabolism and underline the importance of the capability of defensive repair. More than a decade after the free radical theory of ovarian ageing first proposed by Tarin, biological and clinical research has provided numerous evidence that increased reactive oxygen species (ROS), which are among the most important physiological inducers of cellular injury associated with ageing, is a main determinant to follicle ageing. ROS generated by mitochondrial dysfunction is considered the main cause for telomere shortening, chromosomal segregation disorders, maturation and fertilization failures or oocyte/embryo fragmentation. Looking for ROS aetiology and widespread, a relevant role has been ascribed to advanced glycation end products (AGEs) , factors that may hamper ovarian stroma vessels, follicular growth, assembly of an efficient system of antioxidant enzymatic defence as well as development of an efficient perifollicular vascularization. Further evidence for ROS in the ovarian follicle was obtained by research on stress signalling pathways in aged granulosa and cumulus cells. Enzymatic activity and protein level of superoxide dismutase (SOD), the enzyme that reacts with superoxide anion radicals to form oxygen and H2 O2 , were found to decrease with age, and lower levels of SOD activity are associated with unsuccessful IVF outcomes. Nevertheless, there are poor evidences for possible benefits from antioxidant treatments in humans, suggesting that further actors are involved in modulating stress adaptive response in the ovary during agein

Gene expression in cumulus cells and oocyte quality

Infertility is a worldwide growing issue, and female factors account for about 30 % of the total cases of infertility. The majority of couples affected by infertility undergo in vitro fertilization (IVF) protocols following women hormonal hyperstimulation cycles to obtain mature oocytes to fertilize in vitro. Nowadays, the oocyte/embryo quality is mainly assessed by morphokinetic parameters even if these approaches have low objective prediction value. The rate of live newborns after IVF is relatively low, ranging from about 30 % in younger women to 10 % in the older ones. Aging, in fact, is a well-known critical factor for the success of IVF protocols. As a consequence, a primary goal in older women is to increase the pregnancy rate, with a crucial point represented by the selection of the oocytes to fertilize in vitro and transfer in women. In this view, transcriptomic information about granulosa cells (GCs) might shed light on the oocyte viability, thereby providing a non-invasive method of oocyte/embryo selection. The nutritional support and trafficking of macromolecules that this system allows may be particularly important for oocytes due to the avascular nature of the granulose layer. The signaling between GCs and oocyte via cytoplasmic processes penetrating the zona pellucid and forming gap junctions at the oocyte surface is a key means of disseminating local and endocrine signals to the oocyte. In fact, GCs functionality is a key determinant of the oocyte quality and competence, since GCs are the somatic cells strictly connected to the growing oocyte by a bidirectional communication ensuring the environment for its correct development. It is clear that the role of the oocyte extends far beyond its functions in the transmission of genetic information and supply of raw materials to the early embryo. It also has a critical part to play in mammalian follicular control and the regulation of oogenesis, ovulation rate, and fecundity. This chapter is aimed to explore the GCs gene activity in physiological and pathological conditions

MicroRNAs are stored in human MII oocyte and their expression profile changes in reproductive aging

Maternal RNAs are synthesized by the oocyte during its growth; some of them are utilized for oocyte-specific processes and metabolism, others are stored and used during early development before embryonic genome activation. The appropriate expression of complex sets of genes is needed for oocyte maturation and early embryo development. In spite of the basic role of noncoding RNAs in the regulation of gene expression, few studies have analyzed their role in human oocytes. In this study, we identified the microRNAs (miRNAs) expressed in human metaphase II stage oocytes, and found that some of them are able to control pluripotency, chromatin remodeling, and early embryo development. We demonstrated that 12 miRNAs are differentially expressed in women of advanced reproductive age and, by bioinformatics analysis, we identified their mRNA targets, expressed in human oocytes and involved in the regulation of pathways altered in reproductive aging. Finally, we found the upregulation of miR-29a-3p, miR-203a-3p, and miR-494-3p, evolutionarily conserved miRNAs, also in aged mouse oocytes, and demonstrated that their overexpression is antithetically correlated with the downregulation of DNA methyltransferase 3A (Dnmt3a), DNA methyltransferase 3B (Dnmt3b), phosphatase and tensin homolog (Pten), and mitochondrial transcription factor A (Tfam). We propose that oocyte miRNAs perform an important regulatory function in human female germ cells, and their altered regulation could explain the changes occurring in oocyte aging

The natural carotenoid crocetin and the synthetic tellurium compound as101 protect the ovary against cyclophosphamide by modulating sirt1 and mitochondrial markers

Cancer therapies are associated with increased infertility risk due to accelerated reproductive aging. Oxidative stress (OS) is a potential mechanism behind ovarian toxicity by cyclophosphamide (CPM), the most ovotoxic anticancer drug. An important sensor of OS is SIRT1, a NAD+-dependent deacetylase which regulates cellular defence and cell fate. This study investigated whether the natural carotenoid crocetin and the synthetic compound AS101 protect the ovary against CPM by modulating SIRT1 and mitochondrial markers. We found that the number of primordial follicles of female CD1 mice receiving crocetin plus CPM increased when compared with CPM alone and similar to AS101, whose protective effects are known. SIRT1 increased in CPM mouse ovaries revealing the occurrence of OS. Similarly, mitochondrial SIRT3 rose, whilst SOD2 and the mitochondrial biogenesis activator PGC1-α decreased, suggesting the occurrence of mitochondrial damage. Crocetin and AS101 administration prevented SIRT1 burst suggesting that preservation of redox balance can help the ovary to counteract ovarian damage by CPM. Decreased SIRT3 and increased SOD2 and PGC1-α in mice receiving crocetin or AS101 prior to CPM provide evidence for mitochondrial protection. Present results improve the knowledge of ovarian damage by CPM and may help to develop interventions for preserving fertility in cancer patients

Roadmap on thermoelectricity

The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices. In this Roadmap an overview is given about the most recent experimental and computational results obtained within the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices

Female Infertility and Autoimmunity

Autoimmune diseases occur when the immune system attacks and destroys the organs and tissues of its own host. Eighty percent of autoimmune patients are women and autoimmune disorders often start in women of childbearing age. These diseases are a heterogenous group of pathologies. Some are systemic, like systemic lupus erythematosus, antiphospholipid syndrome, polymyositis, dermatomyositis, while others are organ-specific, like thyroid autoimmune disease and celiac disease. The problem with autoimmune disease is that, once it has developed, a wider range of autoimmune reactions may be triggered, so that an individual may develop more than one autoimmune disorder. The following review focuses on thyroid autoimmunity and its association with other autoimmune diseases suspected of interfering with female reproductive outcome

PCOS and Assisted Reproduction Technique: Role and Relevance of Inositols

Polycystic ovary syndrome is an endocrine disorder often characterized by insulin resistance and hyperinsulinemia, especially in overweight/obese women. Among insulin sensitizers, the positive role of inositols has been increasingly established in recent years. The action of inositols not only concerns the metabolic parameters of these patients, but also the hormonal profile, resulting in beneficial effects on ovarian function. For this reason, many studies have tried to recognize their role in PCOS infertile women who underwent in vitro fertilization (IVF) procedures