Effects of GH and IGF1 on Basal and FSH-Modulated Porcine Sertoli Cells In-Vitro

Investigational follicle-stimulating hormone receptor agonists for male infertility therapy

INTRODUCTION

According to estimates by the World Health Organization, about 17.5% of the adult population - roughly 1 in 6 globally - experience infertility. The causes of male infertility remain poorly understood and have yet to be fully evaluated. Follicle-stimulating hormone (FSH) represents an available and useful therapeutic strategy for the treatment of idiopathic infertility.

AREAS COVERED

We provide here an overview of the molecular mechanisms by which FSH stimulates Sertoli cells and the schemes, dosages, and formulations of FSH most prescribed so far and reported in the literature. We also evaluated the possible predictor factors of the response to FSH administration and the indications of the latest guidelines on the use of FSH for the treatment of male infertility.

EXPERT OPINION

FSH therapy should be considered for infertile male patients with oligoasthenoteratozoospermia and normal serum FSH levels to quantitatively and qualitatively improve sperm parameters and pregnancy and birth rates. The grade of evidence is very low to low, due to the limited number of randomized controlled studies and patients available, the heterogeneity of the studies, and the limited effect size. To overcome these limitations, preclinical and clinical research is needed to evaluate the most effective dose and duration of FSH administration.

Zinc restores functionality in porcine prepubertal Sertoli cells exposed to subtoxic cadmium concentration via regulating the Nrf2 signaling pathway

INTRODUCTION

Among substances released into the environment by anthropogenic activities, the heavy metal cadmium (Cd) is known to induce severe testicular injury causing male subfertility/infertility. Zinc (Zn) is another heavy metal that, unlike Cd, is physiologically present in the testis, being essential for spermatogenesis. We aimed to examine the possibility that 50 µM ZnCl₂ could counteract the toxic effects induced by Cd in an in vitro model of porcine prepubertal Sertoli cells (SCs) exposed to both subtoxic (5 μM) and toxic (10 μM) concentrations of CdCl₂ for 48 h.

MATERIALS AND METHODS

Apoptosis, cell cycle, and cell functionality were assessed. The gene expression of Nrf2 and its downstream antioxidant enzymes, ERK1/2, and AKT kinase signaling pathways were evaluated.

MATERIALS AND RESULTS

We found that Zn, in co-treatment with subtoxic and toxic Cd concentration, increased the number of metabolically active SCs compared to Cd exposure alone but restored SC functionality only in co-treatment with subtoxic Cd concentration with respect to subtoxic Cd alone. Exposure of Cd disrupted cell cycle in SCs, and Zn co-treatment was not able to counteract this effect. Cd alone induced SC death through apoptosis and necrosis in a dose-dependent manner, and co-treatment with Zn increased the pro-apoptotic effect of Cd. Subtoxic and toxic Cd exposures activated the Nrf2 signaling pathway by increasing gene expression of Nrf2 and its downstream genes (SOD, HO-1, and GSHPx). Zn co-treatment with subtoxic Cd attenuated upregulation on the Nrf2 system, while with toxic Cd, the effect was more erratic. Studying ERK1/2 and AKT pathways as a target, we found that the phosphorylation ratio of p-ERK1/2 and p-AKT was upregulated by both subtoxic and toxic Cd exposure alone and in co-treatment with Zn.

DISCUSSION

Our results suggest that Zn could counteract Cd effects by increasing the number of metabolically active SCs, fully or partially restoring their functionality by modulating Nrf2, ERK1/2, and AKT pathways. Our SC model could be useful to study the effects of early Cd exposure on immature testis, evaluating the possible protective effects of Zn.

Role of the GH-IGF1 axis on the hypothalamus-pituitary-testicular axis function: lessons from Laron syndrome

BACKGROUND

Animal studies suggest that insulin-like growth factor 1 (IGF1) may influence the function of the hypothalamus-pituitary-testicular axis, especially in childhood, but the evidence in humans is scanty. Laron syndrome, a human model of IGF1 deficiency, may help to solve this issue.

PURPOSE

This systematic review aims to analyze puberty onset and progression, testicular volume, gonadotropin, and total testosterone serum levels, sperm parameters and fertility, and penile length in patients with Laron syndrome.

METHODS

Specific keywords were used. All data on male patients with Laron syndrome were included.

RESULTS

Seventeen articles matched the inclusion criteria and were entered in the analysis, for a total of 125 male patients. Puberty was absent in 8.9% and delayed in 35.6% of untreated patients of pubertal age. After onset, the duration of the pubertal process was prolonged in 76.9% of untreated patients. The growth spurt was absent in 52.6% and delayed in 31.6% of untreated patients. The testicular volume was small in the two patients who did not receive any treatment. Treatment with IGF1 increased gonadotropin and testosterone serum levels in five out of five patients of pubertal age. No effect was found in four out of four patients younger than 5 years. No study reported data on sperm parameters and fertility. Micropenis occurred in 67.2% of patients.

CONCLUSION AND FUTURE PERSPECTIVES

Delayed puberty is common in patients with Laron syndrome. The growth hormone-IGF1 axis may influence the time of puberty onset. Serum levels of IGF1 should be investigated in children with delayed puberty, scarce progression of testicular growth, and/or micropenis. IGF1 levels might be measured in children with delayed puberty, poor testicular growth, and/or micropenis.

Role of Akt and mammalian target of rapamycin signalling in insulin-like growth factor 1-mediated cell proliferation in porcine Sertoli cells

The critical role of insulin-like growth factor (IGF) 1 in promoting Sertoli cell proliferation invivo and invitro has been established, but its downstream signalling mechanisms remain unknown. In addition to mitogenic effects, a role for IGF1 in mediating cholesterol biosynthesis within testes has been implied. The aims of this study were to investigate the roles of: (1) phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (mTOR) signalling in IGF1-mediated Sertoli cell proliferation; and (2) IGF1 in mediating cholesterol biosynthesis in Sertoli cells. Primary cultures of Sertoli cells were prepared from 1-week-old porcine testes. On Day 3 of culture, Sertoli cells were treated with 300ng mL-1 IGF1, alone or in combination with inhibitors of IGF1 receptor (2μM picropodophyllotoxin), Akt (1μM wortmannin) or mTOR (200nM rapamycin). Cells were cultured for 30min and phosphorylation levels of Akt, mTOR and p70 ribosomal protein S6 kinase (p70S6K) were determined by immunoblotting. Cell proliferation and quantitative polymerase chain reaction assays were conducted using cells cultured for 24h. IGF1 increased phosphorylation of Akt, mTOR and p70S6K and cell proliferation, and these effects were inhibited by inhibitors of IGF1R, Akt and mTOR. Furthermore, IGF1 upregulated the expression of cholesterol biosynthetic genes (3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS1) and cytochrome P450, family 5, subfamily A, polypeptide 1 (CYP5A1)), but not sterol regulatory element-binding transcription factor 1 (SREBF1). Increased phosphorylation of p70S6K, a major downstream target of mTOR, and upregulated expression of genes involved in cholesterol biosynthesis are indicative of the key role played by IGF1 in regulating the synthesis of cholesterol, the precursor for steroid hormones.

Severe Acute Respiratory Syndrome Coronavirus 2 and Male Reproduction: Relationship, Explanations, and Clinical Remedies

Coronavirus disease 2019 (COVID-2019) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been an ongoing pandemic and worldwide public health emergency, having drawn a lot of attention around the world. The pathogenesis of COVID-19 is characterized by infecting angiotensin-converting enzyme 2 (ACE2)-expressing cells, including testis-specific cells, namely, Leydig, Sertoli, and spermatogenic cells, which are closely related to male reproduction. This leads to aberrant hyperactivation of the immune system generating damage to the infected organs. An impairment in testicular function through uncontrolled immune responses alerts more attention to male infertility. Meanwhile, the recent clinical data indicate that the infection of the human testis with SARS-CoV-2 may impair male germ cell development, leading to germ cell loss and higher immune cell infiltration. In this review, we investigated the evidence of male reproductive dysfunction associated with the infection with SARS-CoV-2 and its possible immunological explanations and clinical remedies.

Testicular Growth and Pubertal Onset in GH-Deficient Children Treated With Growth Hormone: A Retrospective Study

The prevalence of idiopathic oligozoospermia has been esteemed as high as 75%. An Italian survey has reported bilateral testicular hypotrophy in 14% of final-year high school students. The search for determinants of testicular growth in childhood is important for the primary prevention of spermatogenic failure. Therefore, this retrospective study aimed to evaluate the testicular growth and pubertal onset in deficient children treated recombinant human growth hormone (rhGH). To accomplish this, the clinical charts of 93 patients with GH deficiency (GHD) were carefully reviewed. Their mean age at the time of diagnosis was 11.2 ± 2.4 years. rhGH was administered for 44.0 ± 22.4 months, and the onset of puberty was recorded after a mean of 25.8 ± 22.4 months from the first rhGH administration. As expected, serum insulin-like growth factor 1 (IGF1) levels increased significantly after treatment. Before rhGH therapy, the Tanner stage was I in 59 out of 70 boys (84.3%), II in 8/70 (11.4%), III in 3/70 (4.3%). No one was on stage IV or V. The mean Tanner stage was 1.19 ± 0.51. At the last visit, the Tanner stage was I in 8/72 boys (11.1%), II in 6/72 (8.3%), III in 6/72 (8.3%), IV in 16/72 (22.2%), and V in 36/72 (50.0%). After a mean of 44.0 ± 22.4 months of rhGH treatment, the mean Tanner stage was 4.05 ± 1.30. Patients treated with rhGH showed a significant testicular volume (TV) growth over time, whereas no growth was observed in age-matched but not yet treated patients, even when the age was compatible with a spontaneous start of puberty. The multivariate regression analysis showed that the duration of treatment and the mean rhGH dose significantly predicted the percentage of TV increase. In contrast, age, serum FSH, and IGF1 levels, and final rhGH dose did not impact TV growth over time. In conclusion, these findings suggest that GH may play a role in testicular growth and pubertal onset, despite the descriptive nature of this study. Further properly designed studies are needed to confirm these findings. This knowledge may be useful to implement the diagnostic-therapeutic algorithm in case of a lack of testicular growth in childhood.

Effects of Heshouwuyin on gene expression of the insulin/IGF signalling pathway in rat testis and spermatogenic cells

CONTEXT

The Chinese herbal formula Heshouwu decoction (Heshouwuyin) has protective effects on testicular function in aging male rats, but the mechanism is unknown.

OBJECTIVE

This study investigated whether Heshouwuyin affects the testicular function of aging rats by regulating the insulin/IGF signalling pathway.

MATERIALS AND METHODS

Sixteen-month-old male Wistar rats in the Heshouwuyin group and the natural-aging group were orally administered Heshouwuyin granules (0.056 g/kg) or equivalent normal saline for 60 d. The testicular tissue of 12-month-old male Wistar rats was removed as a young control group (n = 10). The testicular tissue and spermatogenic cells were studied.

RESULTS

The immunofluorescence results revealed that the insulin receptor (INSR)- (0.056 ± 0.00548), insulin receptor substrate 1(IRS1)- (0.251 ± 0.031), IRS2 (0.230 ± 0.019)- and insulin-like growth factor 1 (IGF1)-positive cell rate (0.33 ± 0.04) in the aging group was higher than that in the young control group (0.116 ± 0.011, 0.401 ± 0.0256, 0.427 ± 0.031, 0.56 ± 0.031; p < 0.01), and the IGF-binding protein 3 (IGFBP3)-positive cell rate (0.42 ± 0.024) was lower than that (0.06 ± 0.027) in the young group (p < 0.01). The intervention of Heshouwuyin reversed the above phenomena. The qPCR and immunoblot results were consistent with those of the immunofluorescence. The same results were obtained in spermatogenic cells.

CONCLUSIONS

Our research shows that Heshouwuyin can regulate the insulin/IGF signalling pathway to improve testicular function, and provides an experimental basis for further clinical use.

The 2039 A/G FSH receptor gene polymorphism influences glucose metabolism in healthy men

OBJECTIVE

To assess the role of c. 2039 A/G (p. Asp680Ser) (rs6166) and c. -29 G/A (rs1394205) follicle-stimulating hormone receptor (FSHR) gene single nucleotide polymorphisms (SNPs) in a cohort of healthy men.

METHODS

One-hundred twenty-seven healthy men underwent evaluation of the anthropometric parameters, assessment of metabolic and lipid profile, measurement FSH serum levels, and genotyping of both the aforementioned FSHR SNPs. Data grouped according to the FSHR rs6166 or rs1394205 genotypes underwent to statistical analysis.

MAIN RESULTS

The three groups of men for each FSHR SNP did not differ statistically significantly for body mass index and serum FSH levels. As for FSHR rs6166 SNP, glucose levels were significantly lower in men with the GG genotype compared with those with the AA genotype. Men with AG had lower insulin levels and HOMA index values compared with those carrying the genotype AA (p < 0.05). The GG group showed a negative correlation between serum FSH levels and insulin and between serum FSH levels and HOMA index (p < 0.05). In contrast, men grouped according to the FSHR rs1394205 genotype showed no significant difference in blood glucose, serum insulin levels, and HOMA index. The AG group showed a negative correlation between FSH insulin and between serum FSH levels and HOMA index (p < 0.05).

CONCLUSIONS

Men with the genotype GG of the FSHR rs6166 SNP have lower blood glucose levels than those with the AA genotype. Their FSH levels inversely correlated with insulin and HOMA index. In contrast, the genotype FSHR rs6166 A/G did not reveal any role of FSH on glucose metabolism in healthy men. The inverse relationship between FSH and insulin or HOMA index in the group with the genotype GG of the FSHR rs6166 SNP suggests a possible cross-talk between FSH and insulin.

Single-cell analysis of developing and azoospermia human testicles reveals central role of Sertoli cells

Clinical efficacy of treatments against non-obstructive azoospermia (NOA), which affects 1% of men, are currently limited by the incomplete understanding of NOA pathogenesis and normal spermatogenic microenvironment. Here, we profile >80,000 human testicular single-cell transcriptomes from 10 healthy donors spanning the range from infant to adult and 7 NOA patients. We show that Sertoli cells, which form the scaffold in the testicular microenvironment, are severely damaged in NOA patients and identify the roadmap of Sertoli cell maturation. Notably, Sertoli cells of patients with congenital causes (Klinefelter syndrome and Y chromosome microdeletions) are mature, but exhibit abnormal immune responses, while the cells in idiopathic NOA (iNOA) are physiologically immature. Furthermore, we find that inhibition of Wnt signaling promotes the maturation of Sertoli cells from iNOA patients, allowing these cells to regain their ability to support germ cell survival. We provide a novel perspective on the development of diagnostic methods and therapeutic targets for NOA.

Non-obstructive azoospermia affects 1% of men. Here, authors perform single-cell transcriptomic analysis of human testicular cells from healthy donors and non-obstructive azoospermia patients and find that inhibition of Wnt signaling promotes the maturation of Sertoli cells from patients.

Disorders of Puberty: Endocrinology of the Pre-Pubertal Testis

Male infertility is a widespread condition among western countries. Meta-regression data show that sperm concentration and total sperm count have halved in the last decades. The reasons of this decline are still unclear. The evaluation of testicular function in pre-pubertal children may be effective in the timely detection of Sertoli cell (SC) disfunction, which anticipates the diagnosis of male infertility. The aim of this Special Issue is to gather together in vitro evidence on SC physiology, causes of SC dysfunction, and to suggest a practical approach to be adopted in children.