Sertoli cell-only syndrome: advances, challenges, and perspectives in genetics and mechanisms.

Male infertility can be caused by quantitative and/or qualitative abnormalities in spermatogenesis, which affects men's physical and mental health. Sertoli cell-only syndrome (SCOS) is the most severe histological phenotype of male infertility characterized by the depletion of germ cells with only Sertoli cells remaining in the seminiferous tubules. Most SCOS cases cannot be explained by the already known genetic causes including karyotype abnormalities and microdeletions of the Y chromosome. With the development of sequencing technology, studies on screening new genetic causes for SCOS are growing in recent years. Directly sequencing of target genes in sporadic cases and whole-exome sequencing applied in familial cases have identified several genes associated with SCOS. Analyses of the testicular transcriptome, proteome, and epigenetics in SCOS patients provide explanations regarding the molecular mechanisms of SCOS. In this review, we discuss the possible relationship between defective germline development and SCOS based on mouse models with SCO phenotype. We also summarize the advances and challenges in the exploration of genetic causes and mechanisms of SCOS. Knowing the genetic factors of SCOS offers a better understanding of SCO and human spermatogenesis, and it also has practical significance for improving diagnosis, making appropriate medical decisions, and genetic counseling. For therapeutic implications, SCOS research, along with the achievements in stem cell technologies and gene therapy, build the foundation to develop novel therapies for SCOS patients to produce functional spermatozoa, giving them hope to father children.

MALDI Imaging Mass Spectrometry Reveals Lipid Alterations in Physiological and Sertoli Cell-Only Syndrome Human Testicular Tissue Sections.

Azoospermia, the absence of sperm cells in semen, affects around 15% of infertile males. Sertoli cell-only syndrome (SCOS) is the most common pathological lesion in the background of non-obstructive azoospermia and is characterised by the complete absence of germinal epithelium, with Sertoli cells exclusively present in the seminiferous tubules. Studies have shown a correlation between successful spermatogenesis and male fertility with lipid composition of spermatozoa, semen, seminal plasma or testis. The aim of this research was to discover the correlation between the Johnsen scoring system and phospholipid expressions in testicular cryosections of SCOS patients. MALDI imaging mass spectrometry is used to determine spatial distributions of molecular species, such as phospholipids. Phosphatidylcholines (PCs), phosphatidylethanolamines (PEs) and sphingomyelins (SMs) are the most abundant phospholipids in mammalian cells and testis. SMs, the structural components of plasma membranes, are crucial for spermatogenesis and sperm function. Plasmalogens, are unique PCs in testis with strong antioxidative properties. This study, using imaging mass spectrometry, demonstrates the local distribution of phospholipids, particularly SMs, PCs, plasmalogens and PEs in human testicular samples with SCOS for the first time. This study found a strong relationship between the Johnsen scoring system and phospholipid expression levels in human testicular tissues. Future findings could enable routine diagnostic techniques during microTESE procedures for successful sperm extraction.

Testis cell pyroptosis mediated by CASP1 and CASP4: possible sertoli cell-only syndrome pathogenesis.

BACKGROUND: Sertoli cell-only syndrome (SCOS) is the most serious pathological type of non-obstructive azoospermia. Recently, several genes related to SCOS have been identified, including FANCM, TEX14, NR5A1, NANOS2, PLK4, WNK3, and FANCA, but they cannot fully explain the pathogenesis of SCOS. This study attempted to explain spermatogenesis dysfunction in SCOS through testicular tissue RNA sequencing and to provide new targets for SCOS diagnosis and therapy. METHODS: We analyzed differentially expressed genes (DEGs) based on RNA sequencing of nine patients with SCOS and three patients with obstructive azoospermia and normal spermatogenesis. We further explored the identified genes using ELISA and immunohistochemistry. RESULTS: In total, 9406 DEGs were expressed (Log2|FC|≥ 1; adjusted P value < 0.05) in SCOS samples, and 21 hub genes were identified. Three upregulated core genes were found, including CASP4, CASP1, and PLA2G4A. Thus, we hypothesized that testis cell pyroptosis mediated by CASP1 and CASP4 might be involved in SCOS occurrence and development. ELISA verified that CASP1 and CASP4 activities in the testes of patients with SCOS were significantly higher than those in patients with normal spermatogenesis. Immunohistochemical results showed that CASP1 and CASP4 in the normal spermatogenesis group were mainly expressed in the nuclei of spermatogenic, Sertoli, and interstitial cells. CASP1 and CASP4 in the SCOS group were mainly expressed in the nuclei of Sertoli and interstitial cells because of the loss of spermatogonia and spermatocytes. CASP1 and CASP4 expression levels in the testes of patients with SCOS were significantly higher than those in patients with normal spermatogenisis. Furthermore, the pyroptosis-related proteins GSDMD and GSDME in the testes of patients with SCOS were also significantly higher than those in control patients. ELISA also showed that inflammatory factors (IL-1 ß, IL-18, LDH, and ROS) were significantly increased in the SCOS group. CONCLUSIONS: For the first time, we found that cell pyroptosis-related genes and key markers were significantly increased in the testes of patients with SCOS. We also observed many inflammatory and oxidative stress reactions in SCOS. Thus, we propose that testis cell pyroptosis mediated by CASP1 and CASP4 could participate in SCOS occurrence and development.

Evaluation of cell-free seminal mRNA for the diagnosis of obstruction as the cause of azoospermia in infertile men: A prospective cohort study.

Differentiating obstructive (OA) from non-obstructive (NOA) azoospermia is clinically important in managing infertile men. Classically, the differentiation has been based on clinical, hormonal and histological analysis. Histological tests are invasive and may miss spermatogenic areas. Seminal fluid can serve as a medium to assess the status of spermatogenesis and presence or absence of certain markers can help diagnosing and differentiating azoospermia. We evaluated the role of cell-free seminal markers: DDX4, PRM1 and PRM2 in diagnosing and differentiating between OA and NOA and classifying their subtypes. We observed DDX4 was more sensitive for NOA compared with OA. Among various subtypes of NOA, DDX4 positivity was higher in patients with maturation arrest and hypospermatogenesis compared with Sertoli cell only syndrome. PRM1 and PRM2 had very low positivity rate for any meaningful comparison. Seminal cell-free markers can serve as non-invasive tests in diagnosing and differentiating etiologies of azoospermia but their validity needs to be proved in long-term trials with more refined molecular techniques.

A systemic review and meta-analysis exploring the predictors of sperm retrieval in patients with non-obstructive azoospermia and chromosomal abnormalities.

To identify the most prevalent chromosomal abnormalities in patients with non-obstructive azoospermia (NOA), consolidate their surgical sperm retrieval (SSR) rates and determine the significant predictors of positive SSR in this patient population. A systematic review and meta-analysis were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Fifty-three studies including 2965 patients were identified through searching the PubMed database. Klinefelter Syndrome (KS) was the most prevalent chromosomal abnormality reported in 2239 cases (75.5%). Azoospermia factor c (AZFc) microdeletions were the second most common (18.6%), but men with these deletions had higher SSR rates than patients with KS (41.95% with AZFc vs. 38.63% with KS). When examining predictors of SSR in KS patients, younger age was a significant predictor of positive SSR in patients undergoing microsurgical testicular sperm extraction (micro-TESE). Higher testosterone was a favourable predictor in those undergoing micro-TESE and conventional TESE. Lower luteinizing hormone (LH) and follicular stimulating hormone (FSH) values were significantly associated with positive SSR with testicular sperm aspiration (TESA). No parameter predicted SSR rates in patients with AZFc microdeletions. Overall, genetic abnormalities have significant implications on SSR success in patients with NOA.

Copy number variants within AZF region of Y chromosome and their association with idiopathic male infertility in Serbian population.

Results of numerous studies gave contradictory conclusions when analysing associations between copy number variants (CNVs) within the azoospermia factor (AZF) locus of the Y chromosome and idiopathic male infertility. The aim of this study was to identify the presence and possible association of CNVs in the AZF region of Y chromosome with idiopathic male infertility in the Serbian population. Using the multiplex ligation-dependent probe amplification technique, we were able to detect CNVs in 24 of 105 (22.86%) infertile men and in 11 of 112 (9.82%) fertile controls. The results of Fisher's exact test showed a statistically significant difference between cases and controls after merging g(reen)-r(ed)/g(reen)-r(ed) and b(lue)2/b(lue)3 partial deletions identified in the AZFc region (p = 0.024). At the same time, we observed a trend towards statistical significance for a deletion among gr/gr amplicons (p = 0.053). In addition to these, we identified a novel complex CNV involving inversion of r2/r3 amplicons, followed by b2/b3 duplication and b3/b4 deletion, respectively. Additional analyses on a larger study group would be necessary to draw meaningful conclusions about associations among CNVs that presented with higher frequency in the infertile men than the fertile controls.

Trace the profile and function of circular RNAs in Sertoli cell only syndrome.

Studies increasingly show the involvement of circular RNAs (circRNAs) in several diseases. This study aims to explore the circRNA expression pattern in the testicular tissues of patients with Sertoli only cell syndrome (SCOS) and their potential functions. High throughput circRNA microarray analysis indicated that 399 circRNAs were upregulated and 1195 were down-regulated (fold change >2, P < 0.05) in SCOS relative to obstructive azoospermia (OA). The hsa_circRNA_101222, hsa_circRNA_001387, hsa_circRNA_001153, hsa_circRNA_101373 and hsa_circRNA_103864 were validated by qRT-PCR. Furthermore, the hosting genes of the differentially expressed circRNAs (DEcircRNAs) were enriched in biological processes related to cell cycle and intercellular communication. Also, the overlapping genes between the hosting genes of SCOS-related DEcircRNAs and those highly expressed in Sertoli cells of non-obstructive azoospermia (NOA) were enriched in immune cell development and cell communication. Taken together, aberrantly expressed circRNAs likely mediate SCOS development by regulating the function of Sertoli cells and the spermatogenic microenvironment.

Sertoli cell-only syndrome: etiology and clinical management.

Almost 50% of infertility cases are due to male factors, and spermatogenesis failure is one of the most severe forms of male infertility. Sertoli cell-only syndrome (SCOS) also known as germ cell aplasia is characterized by azoospermia in which the seminiferous tubules of testicular biopsy are lined only with Sertoli cells. The definitive diagnosis of SCOS is by diagnostic testicular biopsy. Although SCOS may be a result of Klinefelter syndrome, most of the SCOS men have a normal karyotype. Along with genetic aberrations, signaling pathways and endocrine processes might be major factors in the development of SCOS. Sperm retrieval and intracytoplasmic sperm injection (ICSI) are available treatments for SCOS. However, some SCOS patients do not have therapeutic options to help them having a biological child. This review aims to summarize our present knowledge about SCOS and to highlight the importance of future researches in the diagnosis and treatment of this disorder.

Expression and localization of retinoid receptors in the testis of normal and infertile men.

Retinoic acid (RA), the active metabolite of vitamin A, is one of the most important factors regulating spermatogenesis. RA activates downstream pathways through its receptors (retinoic acid receptor alpha [RARA], retinoic acid receptor beta, and retinoic acid receptor gamma [RARG]) and retinoid X receptors (retinoid X receptor alpha [RXRA], retinoid X receptor beta [RXRB], and retinoid X receptor gamma [RXRG]). These receptors may serve as therapeutic targets for infertile men. However, the localization and expression of retinoid receptors in normal and infertile men were unknown. In this study, we found RARA and RARG were mostly localized in spermatocytes and round spermatids, RXRB was mainly expressed in Sertoli cells, and RXRG was expressed in most cell types in the fertile human testis. The localization of RARA, RARG, RXRB, and RXRG in men with hypospermatogenesis (HYPO) was similar to that of men with normal fertility. In addition, the messenger RNA expression levels of RARA, RARG, RXRA, RXRB, and RXRG were significantly decreased in men with Sertoli cell-only syndrome (SCOS) and maturational arrest (MA), but not in men with HYPO. These results suggest that reduced levels of RARA, RARG, RXRB, RXRA, and RXRG are more closely associated with SCOS and MA spermatogenetic failure. These results could contribute to the development of new molecular indicators of spermatogenic dysfunction and might provide novel therapeutic targets for treating male infertility.

Ran-binding protein 3 is associated with human spermatogenesis and male infertility.

Ran-binding protein 3 (RanBP3) is a Ran-interacting protein, which participates in the Ran GTPase system in cancer cell biology. However, the expression pattern and physiological role of RanBP3 remain largely unknown. In this study, we found that RanBP3 was expressed in human testes and localised to spermatogonium and spermatocyte of germ cells. In subcellular structure, its localisation is in the nucleus and cytoplasm. Interestingly, compared with normal groups, RanBP3 expression was lower in groups of patients with Maturation Arrest (MA) and Sertoli cell-only syndrome (SCO) when considered by the Johnson Score. RanBP3 expression in the MA group and SCO groups was dramatically lower than that in the normal control group. Studies have shown that RanBP3, which is one of the helper factors of Ran, is mainly participate in the nucleocytoplasmic transport of cells. RanBP3 helps Ran to achieve some functions such as nucleocytoplasmic transport, spindle assembly during mitosis and nuclear assembly after mitosis. Consequent changes in the expression of RanBP3 may associate with human spermatogenesis disorders and male infertility. The identification and characterisation of RanBP3 enhances our understanding of the molecular mechanisms underpinning its function in human spermatogenesis and male infertility.

Decreased expression of MRE11 and RAD50 in testes from humans with spermatogenic failure.

PURPOSE: To assess testicular mRNA and protein expression levels of MRE11 and RAD50 in human azoospermia patients. METHODS: Patients diagnosed with maturation arrest at the spermatocyte stage (MA) and Sertoli cell-only syndrome (SCOS) were recruited through diagnostic testicular biopsy. Patients with normal spermatogenesis were studied as controls. In addition, knockdown of MRE11 and RAD50 was performed in GC-2spd(ts) cells to investigate their roles in cellular proliferation and apoptosis. RESULTS: mRNA and protein expression levels of MRE11 and RAD50 were measured using quantitative polymerase chain reaction, western blotting, and immunohistochemistry, respectively. Knockdown of both MRE11 and RAD50 utilized transfection with small interfering RNAs. CONCLUSION: Our findings demonstrated altered expression levels of MRE11 and RAD50 in human testes with MA and SCOS, and showed that these alterations might be associated with impaired spermatogenesis. These results offer valuable new perspectives into the molecular mechanisms of male infertility.

From exome analysis in idiopathic azoospermia to the identification of a high-risk subgroup for occult Fanconi anemia.

PURPOSE: In about 10% of patients affected by Fanconi anemia (FA) the diagnosis is delayed until adulthood, and the presenting symptom in these "occult" FA cases is often a solid cancer and cancer treatment-related toxicity. Highly predictive clinical parameter(s) for diagnosing such an adult-onset cases are missing. METHODS: (1) Exome sequencing (ES), (2) Sanger sequencing of FANCA, (3) diepoxybutane (DEB)-induced chromosome breakage test. RESULTS: ES identified a pathogenic homozygous FANCA variant in a patient affected by Sertoli cell-only syndrome (SCOS) and in his azoospermic brother. Although they had no overt anemia, chromosomal breakage test revealed a reverse somatic mosaicism in the former and a typical FA picture in the latter. In 27 selected SCOS cases, 1 additional patient showing compound heterozygous pathogenic FANCA variants was identified with positive chromosomal breakage test. CONCLUSION: We report an extraordinarily high frequency of FA in a specific subgroup of azoospermic patients (7.1%). The screening for FANCA pathogenic variants in such patients has the potential to identify undiagnosed FA before the appearance of other severe clinical manifestations of the disease. The definition of this high-risk group for "occult" FA, based on specific testis phenotype with mild/borderline hematological alterations, is of unforeseen clinical relevance.

Spermatogenesis disorder is associated with mutations in the ligand-binding domain of an androgen receptor.

Androgens play a key role in spermatogenesis, and their functions are mediated by the androgen receptor (AR). Some mutations in the AR gene have the potential to alter the primary structure and function of the protein. The aim of this study was to investigate the AR gene mutations in a cohort of males with idiopathic azoospermia referred to Royan Institute. Fifty-one biopsy samples were obtained for routine clinical purposes from 15 men with hypospermatogenesis (HS), 17 patients with maturation arrest (MA) and 19 patients with Sertoli cell-only syndrome (SCOS). The AR cDNAs were prepared from tissue mRNAs and were sequenced. One synonymous variant and three nonsynonymous protein coding single nucleotide polymorphisms (nsSNPs) were detected. Protein structure prediction demonstrated that the S815I and M746T nonsynonymous variants would affect protein structure and its normal function. Our study suggests that mutations in the AR gene would change or disturb the receptor's normal activity. Although these variations may influence spermatogenesis, it is difficult to say that they lead to a lack of spermatogenesis.

Disordered APC/C-mediated cell cycle progression and IGF1/PI3K/AKT signalling are the potential basis of Sertoli cell-only syndrome.

The cause of Sertoli cell-only syndrome (SCOS), a condition in which only Sertoli cells line the seminiferous tubules in the testis, is unknown. Three microarray data sets were downloaded from public databases and were used to compare SCOS and control group. A total of 291 genes differentially expressed (Log2 |FC| ≥ 1 and adjusted p value < 0.05) in SCOS patients. Further 238 genes were significantly downregulated, and 53 genes were significantly upregulated. To identify the hub genes in the differentially expressed genes, we constructed a protein-protein interaction network, and CCNB1, CCNA2, AURKA, KIF11, CCNB2, CDC6, PRC1, NCAPG, KIF2C and PLK4 were screened from the network for the downregulated genes. Since the upregulated genes could not form a network, we concentrated on the genes with a higher fold change, and CPA3, NFIB, LONRF2, LYVE1, ATP8B4, IGF1, ITPR1 and PLAT were identified as the top 50% fold change genes in any of the three microarray data sets. Among downregulated hub genes, CDC6, CCNA2, CCNB1 and CCNB2 were involved in APC/C-mediated cell cycle progression. Among key upregulated genes, IGF1 was involved in the PI3K/AKT pathway, while the other genes have not been reported in Sertoli or Leydig cells. In conclusion, SCOS appears to be caused by disordered APC/C-mediated cell cycle progression and PI3K/AKT signalling.

Duplications in 19p13.3 are associated with male infertility.

PURPOSE: To identify genomic imbalances and candidate loci in idiopathic male infertility. METHODS: Affymetrix CytoScan 750K Array was used to analyze genomic imbalances and candidate loci in 34 idiopathic infertile cases of different phenotypes (hypo-spermatogenesis, n = 8; maturation arrest, n = 7; and Sertoli cell-only syndrome, n = 13, severe oligozoospermia, n = 6, and 10 normozoospermic fertile men). Ten ethnically matched controls were screened for comparison. RESULTS: The cytogenetic array analysis detected a genomic gain at the 19p13.3 region in 9 (26.47%) cases, with the highest frequency in patients with Sertoli cell-only syndrome (SCOS) (38%). Its complete absence in the control group suggests its likely pathogenic nature. In addition to Y-classical, micro, and partial deletions, the duplication in 19p13.3 could serve as a unique biomarker for evaluation of infertility risk. The common region across the individuals harboring the duplication identified STK11, ATP5D, MIDN, CIRBP, and EFNA2 genes which make them strong candidates for further investigations. The largest duplicated region identified in this study displayed a major network of 7 genes, viz., CIRBP, FSTL3, GPX4, GAMT, KISS1R, STK11, and PCSK4, associated with reproductive system development and function. The role of chance was ruled out by screening of ethnically matched controls. CONCLUSION: The result clearly indicates the significance of 19p13.3 duplication in infertile men with severe testicular phenotypes. The present study underlines the utility and significance of whole genomic analysis in the cases of male infertility which goes undiagnosed due to limitations in the conventional cytogenetic techniques and for identifying genes that are essential for spermatogenesis.

Male infertility in Sertoli cell-only syndrome: An investigation of autosomal gene defects.

OBJECTIVES: To detect autosomal genetic defects and to determine candidate genes in Sertoli cell-only syndrome infertile men. METHODS: Single-nucleotide polymorphism + comparative genomic hybridization microarray technology was carried out on 39 Sertoli cell-only syndrome infertile patients in the present study. Array comparative genomic hybridization compares the patient's genome against a reference genome, and identifies uncover deletions, amplifications and loss of heterozygosity. RESULTS: A link between defective spermatogenesis genes and infertility was examined, and amplifications and deletions in several genes were detected, including homeobox gene; synaptonemal complex element protein 1; collagen, type I, alpha 1; imprinted maternally expressed transcript; and potassium voltage-gated channel subfamily Q member 1. CONCLUSIONS: The present data suggest that several genes can play an important role in spermatogenesis and progression of Sertoli cell-only syndrome.

Identification of Premeiotic, Meiotic, and Postmeiotic Cells in Testicular Biopsies Without Sperm from Sertoli Cell-Only Syndrome Patients.

Sertoli cell-only syndrome (SCOS) affects about 26.3⁻57.8% of azoospermic men, with their seminiferous tubules containing only Sertoli cells. Recently, it was reported that testicular biopsies from nonobstructive azoospermic (NOA) patients contained germ cells, and that sperm could be found in the tubules of 20% of SCOS patients using testicular sperm extraction technology. Since the patients without sperm in their testicular biopsies do not have therapy to help them to father a biological child, in vitro maturation of spermatogonial stem cells (SSCs) isolated from their testis is a new approach for possible future infertility treatment. Recently, the induction of human and mice SSCs proliferation and differentiation was demonstrated using different culture systems. Our group reported the induction of spermatogonial cell proliferation and differentiation to meiotic and postmeiotic stages in mice, rhesus monkeys, and prepubertal boys with cancer using 3D agar and methylcellulose (MCS) culture systems. The aim of the study was to identify the type of spermatogenic cells present in biopsies without sperm from SCOS patients, and to examine the possibility of inducing spermatogenesis from isolated spermatogonial cells of these biopsies in vitro using 3D MCS. We used nine biopsies without sperm from SCOS patients, and the presence of spermatogenic markers was evaluated by PCR and specific immunofluorescence staining analyses. Isolated testicular cells were cultured in MCS in the presence of StemPro enriched media with different growth factors and the development of colonies/clusters was examined microscopically. We examined the presence of cells from the different stages of spermatogenesis before and after culture in MCS for 3⁻7 weeks. Our results indicated that these biopsies showed the presence of premeiotic markers (two to seven markers/biopsy), meiotic markers (of nine biopsies, cAMP responsive element modulator-1 (CREM-1) was detected in five, lactate dehydrogenase (LDH) in five, and BOULE in three) and postmeiotic markers (protamine was detected in six biopsies and acrosin in three). In addition, we were able to induce the development of meiotic and/or postmeiotic stages from spermatogonial cells isolated from three biopsies. Thus, our study shows for the first time the presence of meiotic and/or postmeiotic cells in biopsies without the sperm of SCOS patients. Isolated cells from some of these biopsies could be induced to meiotic and/or postmeiotic stages under in vitro culture conditions.

The poly(A) polymerase beta gene may not be associated with azoospermia caused by Sertoli-cell-only syndrome in Japanese patients by comparing patients and normal controls.

Approximately 15% of couples are infertile, with half of these cases being due to a male factor. Testis-specific cytoplasmic poly(A) polymerase beta (PAPOLB) is known to be critical for spermatogenesis. In mice, the loss of function of the Papolb gene results in the arrest of spermiogenesis and in male infertility. To analyse the role of the PAPOLB gene in human male infertility, this study investigated the relevance of this gene to human Sertoli-cell-only syndrome (SCOS) with azoospermia. Mutation analysis of the PAPOLB coding region was performed on 139 Japanese patients by PCR and direct sequence analysis. No critical mutations directly causing SCOS were detected, but three single-nucleotide polymorphisms (SNPs; SNP1 (c1101C > T), SNP2 (c1347T > C) and SNP3 (c1903C > A)) were found in the coding region. However, there were no significant associations in the allelic and genotypic distributions of these three SNPs between the SCOS and control groups (p>.05). This study suggests a lack of association of PAPOLB with azoospermia due to SCOS in humans.

[In vitro culture of the testis tissue of BALB/c mice with spermatogenic dysfunction].

OBJECTIVE: To explore the pathways of development and maturation of the testis tissue in mice with spermatogenic dysfunction in vitro. METHODS: Sixty-eight 8-week-old BALB/c male mice were randomly divided into four groups of equal number, normal control, Sertoli cell only syndrome (SCOS), severe hypo-spermatogenesis (H-S1), and mild hypo-spermatogenesis (H-S2), and the models were established in the latter three groups by intraperitoneal injection of busulfan at 40 mg/kg for 4, 6 and 8 weeks, respectively. The testis tissues of the mice were cultured with the agarose gel method in vitro till the 4th week, followed by determination of the expressions of the marker proteins STRA8 at meiotic initiation, SCP3 during meiosis, and TNP1 after meiosis by immunohistochemistry. The development and maturation of the germ cells during the in vitro culture were evaluated, and their apoptosis detected by TUNEL. RESULTS: The more severe the testicular tissue injury, the lower the expression of the STRA8 protein in the SCOS, H-S1 and H-S2 groups as compared with the normal control before in vitro culture on agarose gel (P < 0.05), and the STRA8 expression was significantly upregulated in the former three groups after 4 weeks of culturing (P < 0.05). The expression of SCP3 was the lowest in the SCOS but the highest in the H-S2 group before culturing (P < 0.05), and was not as high as that in the control, though increased after 4 weeks of culturing. TNP1 was positively expressed in all the mice of the control, some individuals of the H-S1 and H-S2 groups (P< 0.05), but not in the SCOS group at 4 weeks. The apoptosis of germ cells was significantly increased in the SCOS but decreased in the H-S groups compared with that in the normal control after 4 weeks of culturing (P< 0.05). CONCLUSIONS: In vitro culture on agarose gel induces the meiosis of the testis tissue in BALB/c mice with spermatogenic dysfunction, and the effect is even better in those with mild spermatogenic dysfunction.

Leydig cell dysfunction is associated with post-transcriptional deregulation of CYP17A1 in men with Sertoli cell-only syndrome.

STUDY QUESTION: Is the expression of steroidogenic enzyme 17α-Hydroxylase/17,20-Lyase (CYP17A1) down-regulated in Leydig cells (LCs) of men with spermatogenic failure and compensated impairment of LC function, i.e. a low testosterone to LH (T/LH) ratio? SUMMARY ANSWER: Although the transcriptional expression of CYP17A1 is increased, its protein expression is decreased, in isolated LCs of men with spermatogenic failure and reduced serum T/LH. WHAT IS KNOWN ALREADY: Primary spermatogenic defects have been associated with functional and morphological abnormalities of LCs, characterized by decreased serum testosterone (T) levels, decreased T/LH, increased 17ß-estradiol (E2) and E2/T ratio, and larger clusters of LCs (LC hyperplasia). CYP17A1 is a key enzyme in the testosterone pathway and has been implicated in the steroidogenic lesion produced by E2 stimulation. STUDY DESIGN, SIZE, DURATION: We studied 18 azoospermic patients with Sertoli cell-only syndrome (SCOS) and signs of LC dysfunction (cases) and 10 obstructive azoospermic/oligozoospermic men with normal spermatogenesis (controls). The SCOS patients were sub-grouped into 9 cases with T/LH <2 and 9 cases with T/LH ≥2. All of the men underwent testicular biopsy for sperm retrieval at the Reproductive Unit of a University Hospital. PARTICIPANTS/MATERIALS, SETTING, METHODS: The transcriptional expression of CYP17A1 and SF-1 (steroidogenic factor 1) was quantified by SYBR®Green-based qPCR in LCs isolated by laser capture microdissection (LCM), and relative expression to the control pool was assessed. CYP17A1 protein expression was semi-quantified by indirect immunofluorescence (IFI) using Image-Pro Plus v7.0 (Media Cybernetics) in testicular tissue. FSH and LH serum concentrations, and serum and intratesticular T (ITT) and E2 (ITE2) were measured by IRMA and RIA, respectively. MAIN RESULTS AND THE ROLE OF CHANCE: Relative CYP17A1 mRNA expression was increased in cases with T/LH <2 compared to cases with T/LH ≥2, by a mean of 3.3-fold (P = 0.002). No corresponding increase in protein expression was found; in fact, CYP17A1 immunostaining intensity assessed by the Integrated Optical Density (IOD) parameter was lower in the cases with T/LH <2 compared to controls (P = 0.008). Relative SF-1 mRNA expression was similar in both case subgroups. CYP17A1 mRNA expression correlated with ITE2 and intratesticular E2/T (r = 0.536; P = 0.026 and r = 0.542; P = 0.016, respectively), while an inverse association was observed for ITE2 and protein level expression (r = -0.421; P = 0.05). LARGE SCALE DATA: Not applicable. LIMITATIONS REASONS FOR CAUTION: We should interpret the results of the semi-quantification of immunofluorescent staining by Image-Pro Plus software with caution, because it is a semi-quantitative method that may have certain difficulties regarding the disposition of protein in the cells. However, it is not influenced by variations in the number of cells that express the protein, as could be the case of western blot analysis in testicular tissue. WIDER IMPLICATIONS OF THE FINDINGS: Dysfunctional LCs of men with SCOS show post-transcriptional deregulation of CYP17A1, with increased mRNA and decreased protein expression, which may be modulated by increased ITE2 levels. In addition, transcriptional expression of CYP17A1 was not associated with changes in SF-1 mRNA expression. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Fund for Scientific and Technological Development (FONDECYT) of Chile to A.C. [grant number 1120176]. The authors declare no conflict of interest.