Nunziatina Burrello

Sperm aneuploidy in infertile men

A recent line of research has shown that infertile male patients produce cytogenetically abnormal spermatozoa, despite a normal somatic karyotype, as a result of an altered intra-testicular environment that affects negatively the mechanisms controlling chromosome segregation during cell division. The rate of aneuploid spermatozoa production is significantly higher in patients with abnormal sperm parameters compared with those of normozoospermic subjects or infertile patients with normal sperm parameters. All chromosomes are subject to aneuploidy, although at a different rate; the heterochromosomes are more often altered than are the autosomes. A negative correlation has been reported to exist between aneuploidy and the main sperm parameters, suggesting that greater testicular damage is associated with a greater chance of chromosome malsegregation events. Abnormally-shaped spermatozoa are more likely to have chromosome abnormalities, particularly those with an enlarged head. More studies are necessary, however, to evaluate whether other types of sperm head abnormalities are also associated with an abnormal sperm chromosome complement. The possibility of retrieving testicular or epididymal spermatozoa in patients with azoospermia and using them in assisted reproduction techniques has prompted the evaluation of their chromosomal status. Studies have shown that testicular and epididymal spermatozoa have a greater rate of aneuploidy compared with that of ejaculated spermatozoa. Some authors have also shown that patients with non-obstructive azoospermia have a significantly higher sperm aneuploidy rate compared with that of patients with obstructive azoospermia. Sperm aneuploidy seems to have a negative impact on assisted reproduction technique outcome. Although it does not affect the fertilization rate, an elevated sperm aneuploidy rate is associated with a greater rate of pregnancy failure. Nevertheless, some patients with elevated sperm aneuploidy rate can still achieve a pregnancy, but with an increased risk of generating an aneuploid offspring. Thus, sperm aneuploidy evaluation is recommended in infertile patients with abnormal semen parameters, particularly if they undergo IVF programmes.

γ-Aminobutyric acid (GABA) a and b receptors mediate the stimulatory effects of GABA on the human sperm acrosome reaction: interaction with progesterone

OBJECTIVE To evaluate which gamma-aminobutyric acid (GABA) receptor mediates the stimulatory effects of this neurotransmitter on the human sperm acrosome reaction, and to examine the interaction of progesterone, a physiologic inducer of the acrosome reaction, with the GABA(A) receptor. DESIGN Prospective study. SETTING A university clinic of andrology. PATIENT(S) Men with normal sperm analysis parameters. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) The acrosome reaction of motile spermatozoa. RESULT(S) The acrosome reaction was stimulated by GABA in a dose-dependent manner. This effect was inhibited completely by bicuculline, a GABA(A) receptor antagonist, and only partially by saclofen, a GABA(B) receptor antagonist. Accordingly, muscimol, a GABA(A) receptor agonist, stimulated the acrosome reaction to the same extent as GABA, whereas baclofen, a GABA(B) receptor agonist, was less effective. Preincubation with progesterone followed by the addition of GABA resulted in a significant increase in the percentage of acrosome-reacted spermatozoa compared with progesterone alone. However, this increase was less than a simple addition of effects, suggesting that GABA and progesterone act through the same receptor and/or use the same mechanism of action. To test this hypothesis, the ability of progesterone to induce acrosome reaction was tested in the presence of bicuculline, which suppressed the stimulatory effects of progesterone. Given that the GABA(A) receptor is linked to the chloride channel, we tested whether picrotoxin, a blocker of this channel, could modulate the effects of progesterone or GABA. Picrotoxin completely suppressed the acrosome reaction induced by progesterone and only partially suppressed that caused by GABA. CONCLUSION(S) gamma-Aminobutyric acid stimulated the acrosome reaction in human spermatozoa, acting mainly through the GABA(A) receptor and to a lesser extent through the GABA(B) receptor. Progesterone interacted with the GABA(A) receptor to induce the acrosome reaction, and the functional integrity of the chloride channel was vital for this effect.

Glucocorticoids inhibit gonadotropin-releasing hormone by acting directly at the hypothalamic level

Glucocorticoids, the end-product of the hypothalamic-pituitary-adrenal (HPA) axis, suppress gonadotropin release by acting at the level of the pituitary gland. However, experimental evidence suggests that they may also act at the hypothalamic level to suppress gonadotropin-releasing hormone (GnRH) release. The lack of a direct demonstration of this assumption, prompted us to evaluate the effects of glucocorticoids on hypothalamic GnRH release from individually-incubated hemi-hypothalami explanted from male rats. Since testosterone (T), dihydrotestosterone (DHT), and progesterone suppress GnRH release and androgens potentiate the effects of glucocorticoids on GnRH release, we studied also the interaction of these steroids with glucocorticoids on GnRH release. Corticosterone (B), the main glucocorticoid of the rodents with greater affinity for the type I glucocorticoid receptor, and dexamethasone (DEX), a synthetic type II glucocorticoid receptor agonist, were able to suppress basal GnRH release in a concentration-dependent fashion. DEX induced a more profound suppression of GnRH release. Neither T (0.1 nM) nor DHT (0.01 nM) modulated the suppressive effects of low (10 nM) or high (100 nM) concentrations of B on GnRH release. On the other hand, progesterone counteracted the suppressive effect of low concentrations of B (10 nM) on GnRH release, but had no effect on the suppression caused by a higher concentration of B (100 nM). The ability of glucocorticoids to inhibit directly GnRH release suggests that these stress-responsive hormones act also at the hypothalamic level to suppress the reproductive function. The suppressive effect of B was not modulated by androgens, but it was neutralized by progesterone, al least when B was used at low concentrations. We speculate that this steroid “protects” the GnRH-secreting neuron only during basal, but not stress-induced, HPA axis activity when the concentrations of glucocorticoids are more elevated.

Chromosome abnormalities in spermatozoa of patients with azoospermia and normal somatic karyotype

Since epididymal and testicular spermatozoa of azoospermic patients are frequently used for intracytoplasmic sperm injection (ICSI), many studies have been carried out to evaluate their karyotype. This article will review all published data on this topic. In most of the studies, spermatozoa have been retrieved from the testis or the epididymis of patients with nonobstructive (NOA) or obstructive (OA) azoospermia, respectively. Sperm aneuploidy has been evaluated by fluorescence in situ hybridization using probes for sex chromosomes and an array of autosomes. A significantly higher sperm aneuploidy rate has been reported in patients with NOA and OA compared to ejaculated spermatozoa, mainly for sex chromosomes. The magnitude of the increase varies between studies, probably because of the heterogeneity of case selection as well as of the methodology employed. The majority of the studies reported that patients with NOA have a greater sperm aneuploidy rate compared to OA. The greater frequency of sperm aneuploidy in azoospermic patients increases the risk of transmitting a karyotype abnormality to the offspring generated by ICSI.

Chromosome analysis of epididymal and testicular spermatozoa in patients with azoospermia.

Azoospermic patients can now father children once spermatozoa have been retrieved from the epididymis or the testis. However, there are concerns about the risk of chromosomal abnormalities since an increase in sperm aneuploidy rate has been reported in samples from patients with abnormal sperm parameters. The purpose of this study was therefore to evaluate the sperm aneuploidy and diploidy rates for chromosomes 8, 12, 18, X and Y in spermatozoa extracted from the epididymes (n=10) or the testes (n=6) of patients with azoospermia. Ejaculated spermatozoa of healthy men (n=14) served as control. Epididymal and testicular spermatozoa had an aneuploidy rate significantly higher than that found in ejaculated spermatozoa. The aneuploidy and diploidy rates of testicular spermatozoa were higher, but not significantly different, than those found in epididymal spermatozoa. This study has shown that azoospermic patients have an increased sperm aneuploidy rate. They should therefore be given appropriate genetic counselling before entering in-vitro fertilisation programs.

Relationship between tumour necrosis factor α and sex steroid concentrations in the follicular fluid of women with immunological infertility

Experimental evidence suggests a tight relationship between cytokines and the reproductive system. Tumour necrosis factor alpha (TNF alpha), a cytokine produced by activated macrophages and mesenchymal cells, seems to participate in the control of fertility. Therefore, the present study was undertaken to evaluate the concentrations of TNF alpha in the follicular fluid of female patients with immunological infertility, as well as the possible role of this cytokine in follicular development. Concentrations of TNF alpha, 17 beta-oestradiol, progesterone, androstenedione and testosterone were measured in the follicular fluid of patients with immunological infertility and patients with a tubal factor of infertility, who served as a control group. Patients with immunological infertility had significantly higher concentrations of TNF alpha in their follicular fluid compared to the control group. In contrast, oestradiol concentrations were significantly lower in the former group. The intrafollicular concentrations of the other steroids measured did not differ significantly between the two groups. The fertilization rate of ova from follicles included in the study was significantly lower in patients with immunological infertility compared to control subjects (19.1 and 57.1% respectively). In conclusion, this study shows that patients with infertility of immunological origin have increased follicular fluid concentrations of TNF alpha and lower oestradiol concentrations. We speculate that elevated TNF alpha concentrations in the human follicle may negatively influence both ovulation-and fertilization-related events.

Inhibition of oocyte fertilization by assisted reproductive techniques and increased sperm DNA fragmentation in the presence of Candida albicans: a case report

The effects of Candida albicans on sperm parameters and the outcome of infertility treatment are unclear. This report describes a lack of fertilization after assisted reproductive techniques and increased sperm DNA fragmentation in an infertile patient with male accessory gland infection due to Candida albicans. He had normal sperm parameters and, therefore, underwent conventional IVF for a female factor of infertility. No spermatozoa or only one spermatozoon per oocyte were found attached to the zona pellucida of the six mature oocytes retrieved. A new semen sample was then requested from the patient to perform intracytoplasmic sperm injection (ICSI) on the same oocytes, but again no fertilization resulted. Candida albicans was detected in the medium where spermatozoa were co-incubated with oocytes and subsequently in the urethral swabs. It did not have any detrimental effect on sperm parameters soon after ejaculation or following separation of motile spermatozoa by swim-up technique. Fertilization failure after assisted reproduction treatment was associated with an increased percentage of motile spermatozoa having chromatin packaging abnormalities, externalization of phosphatidylserine and DNA fragmentation. In conclusion, Candida albicans did not affect sperm parameters, but increased sperm chromatin packaging damage and apoptosis that might have caused fertilization failure after assisted reproduction treatment in this couple.

Candida albicans experimental infection: effects on human sperm motility, mitochondrial membrane potential and apoptosis

Studies suggest Candida albicans infection has a negative effect on sperm function, including fertilizing ability. Assisted reproduction treatment using spermatozoa from a patient with unrecognized C. albicans infection did not result in fertilization. Preliminary evidence suggested an effect on sperm motility and apoptosis. This study was undertaken to evaluate the effects of experimentally induced C. albicans infection on motility, membrane mitochondrial potential (MMP), chromatin packaging and apoptosis [membrane phosphatidylserine (PS) externalization and DNA fragmentation] of spermatozoa isolated from normozoospermic healthy men. Motile spermatozoa were isolated by swim-up from 13 normal volunteers and exposed to increasing concentrations (0, 1000, 10,000, and 100,000 cfu/ml) of the fungus for 3 and 24 h. C. albicans was isolated from vaginal swabs, after identification, freshly prepared for experiments. Following incubation, sperm motility decreased significantly (P < 0.05 from 10,000 cfu/ml) and spermatozoa with reduced MMP or PS externalization, an early sign of apoptosis, increased in a time- and concentration-dependent manner. Sperm DNA fragmentation and chromatin integrity increased slightly after exposure to C. albicans, but the increase did not reach statistical significance. This study showed that C. albicans infection may decrease the functional competence of spermatozoa by reducing motility and MMP and by promoting molecular apoptosis mechanisms.

Effects of anti-neoplastic treatment on sperm aneuploidy rate in patients with testicular tumor: A longitudinal study

Objective: The adjuvant radio/chemotherapy, usually employed after orchidectomy in patients with testicular tumors, allows a long-term survival with a consequent increased request for fertility. However, little is known about the effects of the anti-neoplastic treatment on sperm cytogenetic asset. Therefore, this prospective, longitudinal study was designed to evaluate the effects of radio- and/or chemotherapyon sperm chromosome. Methods: Eleven patients with testicular tumor were enrolled and underwent sperm aneuploidy rate evaluation before and after 3, 6, 9, 12, 18, 24, and 36 months from radio- and/or chemo-therapy ending. A double and triple multicolor fluorescence in-situ hybridizations for chromosomes 8, 12, 18, X and Y were used to evaluate the sperm aneuploidy rate. To define normal sperm aneuploidy rate, 18 healthy, normozoospermic men were selected as controls. Results: Before treatment, testicular tumor patients had a higher total sperm aneuploidy rate compared with normal men. Total sperm aneuploidy rate showed a slight, but statistically significant increase 6 months after anti-neoplastic treatment. This increase was mainly related to the high sperm aneuploidy rate found in 2 patients which remained elevated up to 12 months in both of them. Conclusion: These results showed that anti-neoplastic treatment caused only slight and transient sperm malsegregation events in patients with testicular tumor. However, since a subset of them had an elevated sperm aneuploidy rate for about 1 yr, we suggest to counsel them to refrain from fatherhood for this length of time.

Asthenozoospermia and membrane remodeling enzymes: a new role for phospholipase A2

Phosholipase A2 (PLA2) activity in the seminal plasma and in sperm heads is closely related to sperm motility and male fertility. Therefore, the purpose of this study was to investigate the possible involvement of different isoforms of phospholipase in asthenozoospermia. To accomplish this, cPLA2, phospho‐cPLA2, iPLA2, and sPLA2 were evaluated by immunofluorescence and immunoblot analyses in spermatozoa obtained from 22 normozoospermic men and 28 asthenozoospermic patients. We found significant differences in cPLA2 and its phosphorylated/activated form, iPLA2, and sPLA2 content and distribution in normal and asthenozoospermic patients. cPLA2 was localized in heads, midpieces, and tails of all spermatozoa as constitutive enzyme, less expressed in the tail of spermatozoa with low progressive motility. While active phospho‐cPLA2 distribution was homogeneous throughout the cell body of control‐donor spermatozoa, lower levels were detected in the tails of asthenozoospermic patients, as opposed to its strong presence in heads. Low immunofluorescence signal for iPLA2 was found in astenozoospermic patients, whereas sPLA2 was significantly lower in the heads of asthenozoospermic patients. Spermatozoa with low progressive motility showed differences both in terms of total specific activity and of intracellular distribution. cPLA2, iPLA2, and sPLA2 specific activities correlated positively and in a significantly manner with sperm progressive motility both in normozoospermic men and asthenozoospermic patients. In conclusion, PLA2s are expressed in different areas of human spermatozoa. Spermatozoa with low motility showed differences in total specific activity and enzyme distributions. We speculated that PLA2 expression and/or different distribution could be potential biomarkers of asthenozoospermia, one of the major causes of male factor infertility.