Successful pregnancy and delivery after testicular sperm extraction despite an undetectable concentration of serum inhibin B in a patient with nonobstructive azoospermia

Proteomics and integrative genomics for unraveling the mysteries of spermatogenesis: the strategies of a team

The strikingly complex structural organization of the mammalian testis in vivo creates particular difficulties for studies of its organization, function and regulation. These difficulties are particularly pronounced for investigations of the molecular communication networks within the seminiferous tubules that govern spermatogenesis. The use of classical molecular and cell biology approaches to unravel this complexity has proved problematic, due to difficulties in maintaining differentiated germ cells in vitro, in particular. The lack of a suitable testing ground has led to a greater reliance on high-quality proteomic and genomic analyses as a prelude to the in vitro antx1d in vivo testing of hypotheses. In this study, we highlight the options currently available for research, as used in our laboratory, in which proteomic and integrative genomic strategies are applied to the study of spermatogenesis in mammals. We will comment on results providing insight into the molecular mechanisms underlying normal and pathological spermatogenesis and new perspectives for the treatment of male infertility in humans. Finally, we will discuss the relevance of our strategies and the unexpected potential and perspectives they offer to teams involved in the study of male reproduction, within the framework of the Human Proteome Project.

SIGNIFICANCE

Integrative genomics is becoming a powerful strategy for discovering the biological significance hidden in proteomic datasets. This work introduces some of the integrative genomic concepts and works used by our team to gain new insight into mammalian spermatogenesis, a remarkably sophisticated process. We demonstrate the relevance of these integrative approaches to understand the cellular cross talks established between the somatic Sertoli cells and the germ cell lineage, within the seminiferous epithelium. Our work also contributes to new knowledge on the pathophysiology of testicular function, with promising clinical applications. This article is part of a Special Issue entitled: 20years of Proteomics in memory of Viatliano Pallini. Guest Editors: Luca Bini, Juan J. Calvete, Natacha Turck, Denis Hochstrasser and Jean-Charles Sanchez.

Inhibins in female and male reproductive physiology: role in gametogenesis, conception, implantation and early pregnancy

A great deal of new information has arisen in the recent years concerning inhibin physiology and clinical relevance in reproductive medicine. It is now recognized that the two inhibin isoforms, named inhibin A and inhibin B, are produced by the gonads in the course of gamete maturation and in women have a different pattern of secretion throughout the menstrual cycle. Since inhibins are also produced by placenta and fetal membranes, it has been suggested that there is an involvement in physiological adaptation of pregnancy. Evidence from several sources has underlined the clinical usefulness of the measurement of inhibin-related proteins in the diagnosis and follow-up of different fertility disturbances and early pregnancy viability. In the male, inhibin B is produced in the testis, principally by the Sertoli cells. Inhibin B expression and secretion are positively correlated with Sertoli cell function, sperm number, and spermatogenic status and are negatively correlated with FSH. This review covers the most recent advances on the role of inhibins in human reproductive function. Considerable progress in the understanding of inhibin physiology has resulted from selective measurement of the two inhibin molecular forms, named inhibin A and B. Newly recognized alterations of inhibin levels in gynaecological diseases as well as in normal and pathological pregnancy are discussed, with particular emphasis on the potential clinical usefulness of assessing inhibin levels in serum and other biological fluids.

Effects of low concentrations of inhibin B on the outcomes of testicular sperm extraction and intracytoplasmic sperm injection

OBJECTIVE

To study the effects of undetectable inhibin B concentrations on the outcomes of testicular sperm extraction (TESE) and of intracytoplasmic sperm injection (ICSI).

DESIGN

Retrospective study.

SETTING

Obstetrics, gynecology, and reproductive biology departments.

PATIENT(S)

We carried out TESE on 75 men with nonobstructive azoospermia: 42 men had an inhibin B concentration of <m15 pg/mL (group 1), and 33 had an inhibin B concentration of > or = 15 pg/mL (group 2). Twenty-five ICSI cycles were carried out using sperm from men in group 1 (group A1), and 35 ISCI cycles were carried out using sperm from men in group 2 (group A2). The outcomes of ICSI in groups A1 and A2 were compared with those of 81 ICSI cycles performed for obstructive azoospermia (group B).

INTERVENTION(S)

Testicular sperm extraction, testicular spermatozoa cryopreservation, and ICSI.

MAIN OUTCOME MEASURE(S)

Testicular sperm extraction outcome, pregnancy, and delivery.

RESULT(S)

Sperm were significantly less likely to be successfully recovered from men in group 1 than from those in group 2 (21% vs. 48%). The inhibin B concentration was significantly lower in men in whom TESE failed, but the FSH concentration did not differ. The implantation rate per embryo transferred was twofold lower in group A1 (7.4%) than in group B (16%), but this difference is not statistically significant.

CONCLUSION(S)

Patients with undetectable inhibin B concentration should be informed of the low chances of positive testicular biopsy, and more embryos should be transferred to improve the success rate.

Inhibin B: a novel marker of spermatogenesis

Subfertility affects about 15% of all couples. Assessment of spermatogenesis has a central role in the evaluation of the subfertile couple. Classical markers of spermatogenesis, such as semen analysis, testicular biopsy and endocrine evaluation all have their diagnostic limitations. There is a clear need for accurate additional markers of spermatogenesis. Recently, the serum inhibin B level has emerged as a sensitive endocrine marker of spermatogenesis. This paper summarises the pros and cons of different markers of spermatogenesis, with specific focus on serum inhibin B. The serum inhibin B level has been shown to be associated with classical markers of spermatogenesis, particularly testicular histology, and to be the most accurate endocrine marker of spermatogenesis. A subnormal serum inhibin B level clearly reflects disturbed spermatogenesis. Before puberty, when no spermatogenesis takes place, inhibin B is a marker of testicular integrity. Clinical applications of serum inhibin B in childhood and adulthood are given, and a view on future directions and research is presented. The serum inhibin B level has proven to be valuable in the evaluation of spermatogenesis, and holds a promise for further research.