Intratesticular testosterone is increased in men with Klinefelter syndrome and may not be released into the bloodstream owing to altered testicular vascularization - a preliminary report

Intratesticular Testosterone and Its Precursors among Azoospermic Men: A Pilot Study

PURPOSE

The study aimed to comprehensively analyze testosterone and precursor concentrations in the testicular interstitial fluid (TIF) of men with azoospermia, exploring their significance in the testicular microenvironment and their correlation with testicular sperm retrieval outcomes.

MATERIALS AND METHODS

We analyzed 37 TIF samples, including 5 from men with obstructive azoospermia (OA) and 32 from men with non-obstructive azoospermia (NOA). Liquid chromatography with tandem mass spectrometry quantified testosterone and precursor levels. Comparative assessments of the outcomes of testicular sperm retrieval were performed between the OA and NOA groups as well as among men with NOA.

RESULTS

Men with NOA who had not undergone hormone treatment exhibited significantly higher intratesticular concentrations of testosterone (median 1,528.1 vs. 207.5 ng/mL), androstenedione (median 10.6 vs. 1.9 ng/mL), and 17-OH progesterone (median 13.0 vs. 1.8 ng/mL) than men diagnosed with OA. Notably, in the subgroup of patients with NOA subjected to medical treatment, men with successful sperm retrieval had significantly reduced levels of androstenedione (median androstenedione 5.7 vs. 18.5 ng/mL, p=0.004). Upon a more detailed analysis of these men who underwent hormone manipulation treatment, the testosterone/androstenedione ratio (indicative of HSD17B3 enzyme activity) was markedly increased in men with successful sperm retrieval (median: 365.8 vs. 165.0, p=0.008) compared with individuals with NOA who had unsuccessful sperm recovery. Furthermore, within the subset of men with NOA who did not undergo medical treatment before microdissection testicular sperm extraction but achieved successful sperm retrieval, the ratio of 17-OH progesterone/progesterone (indicative of CYP17A1 activity) was substantially higher.

CONCLUSIONS

The study suggests distinct testosterone biosynthesis pathways in men with compromised spermatogenesis and those with normal spermatogenesis. Among NOA men with successful retrieval after hormone optimization therapy, there was decreased androstenedione and increased HSD17B3 enzyme activity. These findings have diagnostic and therapeutic implications for the future.

The testicular microvasculature in Klinefelter syndrome is immature with compromised integrity and characterized by excessive inflammatory cross-talk

STUDY QUESTION

Does Klinefelter syndrome (KS) lead to a distinct gene expression pattern at single-cell level in the testes that could provide insight into the reported microvascular dysfunction in the testes?

SUMMARY ANSWER

A distinct gene expression pattern within microvascular-associated cells of males with KS suggests excessive endothelial cell (EC) activation, disorganized vessel formation, and the presence of immature vessels with compromised integrity.

WHAT IS KNOWN ALREADY

Recent studies show that males with KS exhibit microvascular dysfunction in their testes, which affects blood flow and is associated with lower circulating levels of testosterone.

STUDY DESIGN, SIZE, DURATION

A comparative cross-sectional study of males with KS (n = 6), non-obstructive azoospermia (NOA) (n = 5), cryptozoospermia (n = 3), and controls (n = 15) was carried out.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We analyzed publicly available single-cell RNA sequencing data of testicular cells from males with KS, males with NOA, males with cryptozoospermia, and controls. The integration of these datasets allowed us to analyze gene expression profiles and communication patterns among the cell types within the testis and to identify capillary ECs to investigate changes at the microvascular level.

MAIN RESULTS AND THE ROLE OF CHANCE

Rooted in changes at the single-cell level, our study demonstrates a shift in gene expression forming the foundation for altered cellular communication, microvascular remodeling, and pro-inflammatory responses within the testes of males with KS. We identified genes that were dysregulated in capillary ECs from males with KS (Padj < 0.05). Specifically, the unique microvascular gene expression in males with KS indicated enhanced capillary EC activation and increased inflammatory cross-talk, leading to impaired vessel maturation and increased EC barrier permeability.

LIMITATIONS, REASONS FOR CAUTION

Our study is constrained by an unbalanced design, with varying sample sizes and number of cells within each group. We acknowledge the restricted access to clinical information. In addition, our findings were deduced from changes in gene expression, which limits us to infer potential biological consequences arising from these alterations. Furthermore, the absence of a pre-pubertal age group limits the generalizability of our findings and warrants further investigation.

WIDER IMPLICATIONS OF THE FINDINGS

This study offers novel insights into the testicular pathophysiology in KS and underscores the potential contribution of microvascular dysfunction to the hypogonadism and infertility observed in males with KS. While this study aims to better understand the microvascular dysfunction in KS, the precise connections to testosterone deficiency and testicular atrophy remain to be fully elucidated.

STUDY FUNDING/COMPETING INTEREST(S)

A.S. was supported by the Independent Research Fund Denmark (0134-00130B). C.H.G. was supported by Novo Nordisk Foundation (NNF15OC0016474, NNF20OC0060610), 'Fonden til lægevidenskabens fremme', the Familien Hede Nielsen foundation and the Independent Research Fund Denmark (0134-00406A). E.B.J. was supported by Aarhus University and E.B.J. and C.H.G by the Independent Research Fund Denmark (2096-00165A). J.M.K. was supported by Lundbeckfonden (R307-2018-3667), Carlsberg Fonden (CF19-0687), Novo Nordisk Fonden (0073440) and Steno Diabetes Center Aarhus (SDCA). The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Leydig cell metabolic disorder act as a new mechanism affecting for focal spermatogenesis in Klinefelter syndrome patients: a real world cross-sectional study base on the age

Background

Klinefelter's syndrome (KS) was once considered infertile due to congenital chromosomal abnormalities, but the presence of focal spermatozoa changed this. The key to predict and promote spermatogenesis is to find targets that regulate focal spermatogenesis.

Objective

To explore the trend of fertility changes in KS patients at different ages and identify potential therapeutic targets.

Methods

Bibliometric analysis was used to collect clinical research data on KS from the Web of Science Core Collection (WoSCC) from 1992 to 2022. A cross-sectional study was conducted on 75 KS patients who underwent microscopic testicular sperm extraction (mTESE) from 2017 to 2022 in the real world. The reproductive hormones, testicular histopathology, androgen receptors, insulin-like factor 3 (INSL3) receptors and sperm recovery rate (SRR) were analyzed.

Results

Male infertility, dysplasia, Sertoli cells, Leydig cells, testosterone and spermatogenesis were the research focuses related to KS. Luteinizing hormone (LH), testosterone, and INSL3 were evaluation indicators of Leydig cell function that fluctuate with age. Testosterone and LH peaked at ages 13-19 and 30-45, while INSL3 only peaked at ages 13-19. 27 patients (27/75) recovered sperm through mTESE and experienced SRR peaks at the ages of 20, 28, 34, and 37. The SRR of fibrosis patients was 46.15%, fatty degeneration was 7.14%, and melanosis was 40.00%. The INSL3 and androgen receptors were highly expressed and roughly balanced in focal spermatogenesis.

Conclusion

Abnormal metabolism of Leydig cells led to imbalanced expression of INSL3 and androgen receptors, which might be a potential target for spermatogenesis in KS.

Testicular Dysfunction in 47,XXY Boys: When It All Begins. A Semilongitudinal Study

OBJECTIVE

Klinefelter syndrome is the most common chromosomal disorder in males and the most common cause of hypergonadotropic hypogonadism. We describe the natural history of testicular dysfunction in patients with Klinefelter syndrome through the integration of clinical, hormonal, and quantitative ultrasound data in a life-course perspective.

DESIGN

Prospective semilongitudinal study.

METHODS

We included 155 subjects with 47,XXY karyotype (age range: 7 months-55 years) naïve to testosterone replacement therapy. Subjects were divided according to pubertal stage and age group (transition age and adults). Serial clinical, hormonal, and testicular ultrasound (US) assessments were performed.

RESULTS

Testicular development progresses until Tanner stage 4, with subsequent regression, whereas Sertoli and germ cell impairment is not hormonally detected before Tanner stages 3-4, as reflected by normal inhibin B values until stage 4 and the fall in the inhibin B/follicle-stimulating hormone ratio thereafter. The testosterone/luteinizing hormone ratio peaks during Tanner stages 2-3 and declines from Tanner stage 4 onward, preceding the development of overt hypogonadism. US echotexture progressively worsens until transition age, reflecting ongoing gonadal compromise, whereas quantitative US echotexture measures and the presence of both hypoechoic lesions and microlithiasis independently and significantly predict a lower circulating testosterone level.

CONCLUSIONS

The findings from this large prospective study contribute to our understanding of the natural history of testicular dysfunction in Klinefelter syndrome, underlining the importance of quantitative testicular US in infancy and childhood, as well as during pubertal development and transition age, for the optimal care of Klinefelter syndrome patients.

Successful Bilateral Sperm Retrieval in a Hypogonadal Patient with Non-Obstructive Azoospermia Showing Normal Serum 17-Hydroxyprogesterone Levels Suggestive of Normal Intratesticular Testosterone Production: A Case Report

The impact of hypogonadism on the probability of retrieving testicular sperm from patients with non-obstructive azoospermia (NOA) is still a matter of debate. Conflicting evidence in this field may be justified by the striking differences between serum and intratesticular testosterone (ITT) levels found in men with severe spermatogenic dysfunction, so that normal ITT levels may coexist with low serum testosterone levels. Here we report the case of a patient with NOA with a steadily reduced serum testosterone level irresponsive to hormonal stimulation with human chorionic gonadotropin. Supported by his normal serum 17-hydroxyprogesterone (17 OHP) levels, previously suggested to be marker of ITT levels, microdissection testicular sperm extraction was performed for both testes on two separate occasions, resulting in the retrieval of enough sperm for ICSI. Three ICSI cycles were then performed, one blastocyst was transferred, and five were cryopreserved. This case report suggests that normal serum 17 OHP levels, being suggestive of normal ITT levels, may support the decision to proceed with surgical sperm retrieval in hypogonadal patients with NOA, even for those irresponsive to hormonal treatment.

The Klinefelter Syndrome and Testicular Sperm Retrieval Outcomes

Klinefelter syndrome (KS), caused by the presence of an extra X chromosome, is the most prevalent chromosomal sexual anomaly, with an estimated incidence of 1:500/1000 per male live birth (karyotype 47,XXY). High stature, tiny testicles, small penis, gynecomastia, feminine body proportions and hair, visceral obesity, and testicular failure are all symptoms of KS. Endocrine (osteoporosis, obesity, diabetes), musculoskeletal, cardiovascular, autoimmune disorders, cancer, neurocognitive disabilities, and infertility are also outcomes of KS. Causal theories are discussed in addition to hormonal characteristics and testicular histology. The retrieval of spermatozoa from the testicles for subsequent use in assisted reproduction treatments is discussed in the final sections. Despite testicular atrophy, reproductive treatments allow excellent results, with rates of 40–60% of spermatozoa recovery, 60% of clinical pregnancy, and 50% of newborns. This is followed by a review on the predictive factors for successful sperm retrieval. The risks of passing on the genetic defect to children are also discussed. Although the risk is low (0.63%) when compared to the general population (0.5–1%), patients should be informed about embryo selection through pre-implantation genetic testing (avoids clinical termination of pregnancy). Finally, readers are directed to a number of reviews where they can enhance their understanding of comprehensive diagnosis, clinical care, and fertility preservation.

Testicular microlithiasis in paediatric patients with Klinefelter syndrome from infancy till adolescence: early start of degenerative process in the testes-preliminary results

To present the results of testicular ultrasonography supported by clinical and hormonal aspects in paediatric patients with Klinefelter syndrome (KS). Prospective analysis of medical files of 20 patients diagnosed with KS between 2016 and 2022. Assessed data included analysis of causes of referral, ultrasound, and clinical characterisation with hormonal evaluation of serum FSH, LH, testosterone, inhibin B, and anti-Müllerian hormone. Non-mosaic Klinefelter syndrome (47, XXY) was diagnosed in 65% of cases (13/20) by the geneticist (including 7 cases prenatally), in 25% (5/20) by the endocrinologist and in 10% (2/20) by the hematologist. Ultrasound assessment revealed bilateral testicular microlithiasis (TM) in all patients. The youngest KS patient with TM was 3 months old. TM patterns have not changed during follow-ups of up to 6 years in any of the patients. In all KS patients markedly reduced echogenicity and in pubertal KS patients, also irregular echostructure of the testes was observed. The hormonal patterns observed in the study group were typical for those already described in KS. Sertoli and Leydig cell function was intact in prepubertal patients and deteriorated after the start of puberty.

CONCLUSION

Although the degenerative process in the testicular tissue starts very early in the testes in KS and is reflected in morphological changes seen in ultrasonography, Sertoli and Leydig cell hormonal function is normal in prepubertal KS patients.

WHAT IS KNOWN

• So far, normal Leydig and Sertoli cell function was observed in infants and prepubertal KS patients.

WHAT IS NEW

• The morphological changes in the testes in KS may already be seen in early infancy.

Transcriptomic differences between fibrotic and non-fibrotic testicular tissue reveal possible key players in Klinefelter syndrome-related testicular fibrosis

Klinefelter syndrome (KS; 47,XXY) affects 1-2 in 1000 males. Most men with KS suffer from an early germ cell loss and testicular fibrosis from puberty onwards. Mechanisms responsible for these processes remain unknown. Previous genomics studies on testis tissue from men with KS focused on germ cell loss, while a transcriptomic analysis focused on testicular fibrosis has not yet been performed. This study aimed to identify factors involved in the fibrotic remodelling of KS testes by analysing the transcriptome of fibrotic and non-fibrotic testicular tissue. RNA sequencing was performed to compare the genes expressed in testicular samples with (KS and testis atrophy) and without (Sertoli cell-only syndrome and fertile controls) fibrosis (n = 5, each). Additionally, differentially expressed genes (DEGs) between KS and testis atrophy samples were studied to reveal KS-specific fibrotic genes. DEGs were considered significant when p < 0.01 and log2FC > 2. Next, downstream analyses (GO and KEGG) were performed. Lastly, RNA in situ hybridization was performed to validate the results. The first analysis (fibrotic vs non-fibrotic) resulted in 734 significant DEGs (167 up- and 567 down-regulated). Genes involved in the extracellular structure organization (e.g. VCAM1) were found up-regulated. KEGG analysis showed an up-regulation of genes involved in the TGF-β pathway. The KS vs testis atrophy analysis resulted in 539 significant DEGs (59 up- and 480 down-regulated). Chronic inflammatory response genes were found up-regulated. The overlap of X-linked DEGs from the two analyses revealed three genes: matrix-remodelling associated 5 (MXRA5), doublecortin (DCX) and variable charge X-Linked 3B (VCX3B). RNA in situ hybridization showed an overexpression of VCAM1, MXRA5 and DCX within the fibrotic group compared with the non-fibrotic group. To summarize, this study revealed DEGs between fibrotic and non-fibrotic testis tissue, including VCAM1. In addition, X-linked fibrotic genes were revealed, e.g. MXRA5, DCX and VCX3B. Their potential role in KS-related testicular fibrosis needs further study.

Testosterone Deficiency is Not Protective Against the Development of Adenocarcinoma of the Prostate in a Type 1 Diabetic Patient

We present a case of prostate cancer (PC) developing in a hypogonadal patient with well-controlled type 1 diabetes. The purpose of reporting this case is to emphasize that regular prostate examinations and prostate-specific antigen (PSA) measurements should be preformed in the diabetic male, even though the incidence of PC is lower in this group of patients. In addition, these examinations and tests need to be preformed even in the hypogonadal patient with diabetes since the presence of a low serum testosterone (T) level does not preclude the development of PC. This is because the development of PC is not related to serum androgen levels but to the androgen levels within the prostate, and dihydrotestosterone (DHT) levels and not T levels within the prostate gland are responsible for the development of PC. In the hypogonadal male, intraprostatic DHT may be high since DHT can be formed from adrenal androgens, particularly androstenedione, through activation of 5α-reductase 2, which is the minority enzyme in the normal prostate but becomes the major enzyme in the formation and growth of PC.

Leptin secreted from testicular microenvironment modulates hedgehog signaling to augment the endogenous function of Leydig cells

Although testosterone deficiency (TD) may be present in one out of five men 40 years or older, the factors responsible for TD remain largely unknown. Leydig stem cells (LSCs) differentiate into adult Leydig cells (ALC) and produce testosterone in the testes under the pulsatile control of luteinizing hormone (LH) from the pituitary gland. However, recent studies have suggested that the testicular microenvironment (TME), which is comprised of Sertoli and peritubular myoid cells (PMC), plays an instrumental role in LSC differentiation and testosterone production under the regulation of the desert hedgehog signaling pathway (DHH). It was hypothesized that the TME releases paracrine factors to modulate LSC differentiation. For this purpose, cells (Sertoli, PMCs, LSCs, and ALCs) were extracted from men undergoing testis biopsies for sperm retrieval and were evaluated for the paracrine factors in the presence or absence of the TME (Sertoli and PMC). The results demonstrated that TME secretes leptin, which induces LSC differentiation and increases testosterone production. Leptin's effects on LSC differentiation and testosterone production, however, are inversely concentration-dependent: positive at low doses and negative at higher doses. Mechanistically, leptin binds to the leptin receptor on LSCs and induces DHH signaling to modulate LSC differentiation. Leptin-DHH regulation functions unidirectionally insofar as DHH gain or loss of function has no effect on leptin levels. Taken together, these findings identify leptin as a key paracrine factor released by cells within the TME that modulates LSC differentiation and testosterone release from mature Leydig cells, a finding with important clinical implications for TD.

Retrospective analysis of factors affecting sperm retrieval with microscopic testicular sperm extraction in infertile men with Klinefelter syndrome: A multicentre study

The aim of this study was to evaluate the data currently available on predictors of sperm retrieval (SR) in infertile men with Klinefelter syndrome (KS). The data of infertile patients with KS who were evaluated for primary infertility in the andrology outpatient clinics of six centres were retrospectively reviewed. SR, fertilization and pregnancy rates were evaluated. While SR was achieved with microscopic testicular sperm extraction (mTESE) in 57.7% of the cases, the positive pregnancy rate was 22%. While mosaicism was significantly associated with achieving pregnancy, it was not significant for SR (p = 0.002 and p = 0.136 respectively). However, receiving medical treatment prior to mTESE was a positive factor for both achieving pregnancy (p = 0.010) and successful SR (p = 0.032). Unsurprisingly, fertilization rate was a variable that increased the pregnancy rate (p = 0.001). In addition, total testosterone value correlated with SR (p < 0.001). For patients with KS, pregnancy can be achieved by obtaining sperm through mTESE, especially in those with mosaic karyotype, normal partner fertility, a high fertilization rate and who receive appropriate medical treatment before mTESE.

Testicular Microvascular Flow Is Altered in Klinefelter Syndrome and Predicts Circulating Testosterone

CONTEXT

Experimental studies on Klinefelter syndrome (KS) reported increased intratesticular testosterone (T) levels coexisting with reduced circulating levels. Abnormalities in testicular microcirculation have been claimed; however, no studies investigated in vivo testicular blood flow dynamics in humans with KS.

OBJECTIVE

To analyze the testicular microcirculation in KS by contrast-enhanced ultrasonography (CEUS) and correlate vascular parameters with endocrine function.

DESIGN AND SETTING

Prospective study. University setting.

PATIENTS

Sixty-eight testicular scans, 34 testes from 19 T-naïve subjects with KS and 34 testes from age-matched eugonadal men (control) who underwent CEUS for incidental nonpalpable testicular lesions.

MAIN OUTCOMES

CEUS kinetic parameters.

RESULTS

CEUS revealed slower testicular perfusion kinetics in subjects with KS than in age-matched controls. Specifically, the wash-in time (P = 0.018), mean transit time (P = 0.035), time to peak (P < 0.001), and wash-out time (P = 0.004) were all prolonged. Faster testicular blood flow was associated with higher total T levels. Principal component analysis and multiple linear regression analyses confirmed the findings and supported a role for reduced venous blood flow as independent predictor of total T levels.

CONCLUSIONS

Testicular venous blood flow is altered in KS and independently predicts T peripheral release.

Endocrine, sexual and reproductive functions in patients with Klinefelter syndrome compared to non-obstructive azoospermic patients

AIMS

We aimed to investigate fertilisation rates, quality of embryo, pregnancy and live birth rates, endocrine, sexual function, psychological status and quality of life of cases diagnosed with Klinefelter syndrome (KS).

METHODS

Clinical findings, hormone values and semen analyses in patients with nonmosaic KS (Group 1, n = 121) and those with non-genetic nonobstructive azoospermia (NOA) (Group 2, n = 178) were retrospectively analysed. Sperm retrieval outcomes with microdissection testicular sperm extraction (micro-TESE), fertilisation rates and embryo quality, pregnancy, abortion and live birth rates were compared. Sexual functions were assessed using IIEF-15, quality of life was evaluated and psychological status was assessed.

RESULTS

There was no difference in terms of age between groups. Sperm retrieval rates was 38% and 55.6% in Groups 1 and 2, respectively (P = .012). Sperm retrieval rates were higher in Group 1 before 31.5 years than in Group 2 (AUC = 0.620 and 0.578). Compared to Group 2, the fertilisation rate was low in Group 1, whereas embryo quality was similar. Live birth rates were 12.5% and 23% in Groups 1 and 2, respectively (P = .392). The education level, libido, erectile functions and general health satisfaction were lower in Group 1 than in Group 2 (P < .005). Depression and anxiety levels were higher in Group 2 than Group 1 (P < .001).

CONCLUSION

Higher sperm retrieval rate has been achieved in Group 1 younger than 31.5 years. Similar embryo quality is provided between groups. Sexual dysfunction and psychiatric problems were higher in Group 1, with lower satisfaction and general health than Group 2. Patients with KS should be monitored not only with their reproductive functions but also with their general health status.

Testicular immune cells and vasculature in Klinefelter syndrome from childhood up to adulthood

STUDY QUESTION

Is the distribution of immune cells and the testicular vasculature altered in testicular biopsies from patients with Klinefelter syndrome (KS)?

SUMMARY ANSWER

Increased numbers of macrophages and mast cells, an increased expression of decorin and an increased blood vessel density were found in KS samples compared to controls.

WHAT IS KNOWN ALREADY

Most KS patients are infertile due to an early germ cell loss. From puberty onwards, testicular fibrosis can be detected. How this fibrotic process is initiated remains unknown.

STUDY DESIGN, SIZE, DURATION

In this study, the number of macrophages, mast cells and their secretory products were evaluated in KS, Sertoli cell only (SCO) and control patient samples. The association between immune cell numbers and level of fibrosis in KS tissue was examined. In addition, the vascularization within these testicular tissue biopsies was studied. For immunohistochemical evaluation, KS patients at different stages of testicular development were included: prepubertal (aged 4-7 years; n = 4), peripubertal (aged 11-17 years; n = 21) and adult (aged >18 years; n = 37) patients. In addition, testicular tissue biopsies of adult SCO (n = 33) and control samples for the three KS age groups (prepubertal n = 9; peripubertal n = 5; adult n = 25) were analysed. Gene expression analysis was performed on adult testicular tissue from KS (n = 5), SCO (n = 5) and control (n = 5) patients.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Adult (>18 years) KS, SCO and control testicular tissue biopsies were obtained during a testicular sperm extraction procedure. KS peripubertal (11-18 years), prepubertal (<11 years) and age-matched control biopsies were obtained from the biobank of the university hospital. Immunohistochemistry was used to determine the tubular structure (H/PAS), the number of spermatogonia (MAGE-A4), macrophages (CD68) and mast cells (tryptase) and the blood vessel density (Von Willebrand factor). In addition, quantitative real-time polymerase chain reaction was used to determine the expression of secretory products of macrophages and mast cells (tryptase, tumour necrosis factor alpha and decorin).

MAIN RESULTS AND THE ROLE OF CHANCE

A significant increase in the number of macrophages (P < 0.0001) and mast cells (P = 0.0008) was found in the peritubular compartment of testes of adult KS patients compared to control samples. However, no association between the number of immune cells and the degree of fibrosis was observed. In adult SCO samples, a significant increase was seen for peritubular macrophage (P < 0.0001) and mast cell (P < 0.0001) numbers compared to control samples. In the interstitial compartment, a significant increase in mast cell number was found in adult SCO samples compared to KS (P < 0.0001) and control (P < 0.0001) tissue. A significant difference (P = 0.0431) in decorin expression could be detected in adult KS compared to control patients. Decorin expression was mostly seen in the walls of the seminiferous tubules. When comparing the vascularization between KS patients and age-matched controls, a significant increase (P = 0.0081) in blood vessel density could be observed only in prepubertal KS testicular tissue.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

As controls for this study, testicular tissue biopsies of men who underwent a vasectomy reversal or orchiectomy were used, but these men may not represent fertile controls. In addition, a high variability in immune cell numbers, secretory products expression and number of blood vessels could be observed amongst all patient samples.

WIDER IMPLICATIONS OF THE FINDINGS

Increased numbers of macrophages and mast cells have previously been described in non-KS infertile men. Our results show that these increased numbers can also be detected in KS testicular tissue. However, no association between the number of macrophages or mast cells and the degree of fibrosis in KS samples could be detected. Decorin has previously been described in relation to fibrosis, but it has not yet been associated with testicular fibrosis in KS. Our results suggest a role for this proteoglycan in the fibrotic process since an increased expression was observed in adult KS tissue compared to controls. Impaired vascularization in KS men was suggested to be responsible for the KS-related disturbed hormone levels. Our results show a significant difference in blood vessel density, especially for the smallest blood vessels, between prepubertal KS samples and age-matched controls. This is the first study to report differences between KS and control testicular tissue at prepubertal age.

STUDY FUNDING/COMPETING INTEREST(S)

The project was funded by grants from the Vrije Universiteit Brussel (E.G.) and the scientific Fund Willy Gepts from the UZ Brussel (D.V.S.). D.V.S. is a post-doctoral fellow of the Fonds voor Wetenschappelijk Onderzoek (FWO; 12M2819N). No conflict of interest is declared for this research project.

Central hypogonadism in Klinefelter syndrome: report of two cases and review of the literature

PURPOSE

Klinefelter syndrome (KS) is characterized by late adolescence/young adulthood onset of primary hypogonadism. Hypogonadotropic hypogonadism (HH), when congenital, is usually associated with absent/incomplete puberty and low/normal gonadotropins. We report the clinical and genetic features of two subjects with KS and an unexpected HH hormone profile.

METHODS

Magnetic resonance imaging (MRI) of hypothalamus-pituitary region and next generation sequencing (NGS) of congenital HH-associated genes were obtained. A narrative review of the literature was conducted.

RESULTS

Patients were diagnosed with Klinefelter syndrome following karyotype analysis. Nevertheless, they showed unusual features: both had incomplete puberty, low gonadotropins and testosterone levels, and the first one was anosmic. Sellar lesions were excluded by MRI, and NGS was negative in both subjects. Our data add to those of the only 14 similar cases reported so far. Unexplained HH rarely occurs in KS and is variably associated with anosmia, other pituitary hormones deficiencies and heterogeneous karyotypes. However, most cases show an early, pre-pubertal onset of hypogonadism. If the causes behind this gonadotropins defect are largely unknown, hereby we provide the first review of the literature on this topic and propose some pathogenetic hypotheses, including the coexistence of KS and congenital HH as suggested by overlapping clinical features in some of these patients.

CONCLUSION

HH is an exceptional occurrence in Klinefelter syndrome and is associated with heterogeneous phenotypes and, probably, aetiologies. Moreover, KS could underlie HH nonresponsive to gonadotropins. An exhaustive diagnostic workup and a tailored clinical management are advisable in these rare forms.

Testicular Involvement is a Hallmark of Apo A-I Leu75Pro Mutation Amyloidosis

CONTEXT

Apo A-I Leu75Pro is a rare hereditary form of amyloidosis that mainly involves the kidney, the liver, and the testis.

OBJECTIVE

To define the characteristics of organ damage and testis impairment in the largest cohort collected to date of men with Apo A-I Leu75Pro amyloidosis.

DESIGN, SETTING, AND PATIENTS

Retrospective study from a prospectively collected database of 129 male subjects >18 years with Apo A-I Leu75Pro amyloidosis from a reference center at the University Hospital of Brescia, Italy.

MAIN OUTCOME MEASURES

We evaluated liver and renal function, scrotal ultrasound, reproductive hormone levels, testis biopsy, hypogonadal symptoms, and fertility.

RESULTS

Progressive involvement of testis, kidney, and liver was observed in 96/129 (74.4%) cases. Testis impairment was found in 88/129 patients (68.2%), liver in 59 (45.7%) and renal in 50 (38.8%). Testis damage was often the first manifestation of the disease and the only dysfunction in 30% of younger patients (<38 years). Testicular involvement was characterized mainly by primary (73/88 patients, 83.0%) and subclinical (8/88, 9.1%) hypogonadism. Almost all (85/88, 96.6%) also had high follicle-stimulating hormone, suggesting a primary global damage of endocrine and spermatogenic functions, and 30% of them did not conceive. Macroorchidism was found in 53/88 (60.2%) patients, especially in men <54 years (30/33, 90.9%). Apo A-I amyloid deposits were found in Sertoli cells, germinal epithelium, and vessel walls.

CONCLUSION

In men with Apo A-I Leu75Pro amyloidosis, testicular involvement is the hallmark of the disease, characterized by global primary testicular dysfunction and macroorchidism due to amyloid deposits.

Infertility considerations in klinefelter syndrome: From origin to management

Klinefelter syndrome (KS) is defined as the presence of one or more extra "X" chromosome in a male patient. It affects approximately 1 in 600 newborn males and the most common chromosomal abnormality, leading to male hypogonadism and infertility. There is a lack of data supporting best practices for KS patients' care. In this paper we review controversial issues in KS research ranging from mechanisms of variation in KS phenotype to abnormalities resulting in reduced sperm production to successful sperm retrieval disparities after testicular sperm extraction (TESE). Translation to live birth and offspring health is also examined. Finally, medical therapies used to optimize the hormonal status and chances of fertility in KS patients are reviewed. We will also discuss the experimental spermatogonial stem cell (SSC) treatments, which are considered the future for TESE negative patients.

European academy of andrology guidelines on Klinefelter Syndrome Endorsing Organization: European Society of Endocrinology

BACKGROUND

Knowledge about Klinefelter syndrome (KS) has increased substantially since its first description almost 80 years ago. A variety of treatment options concerning the spectrum of symptoms associated with KS exists, also regarding aspects beyond testicular dysfunction. Nevertheless, the diagnostic rate is still low in relation to prevalence and no international guidelines are available for KS.

OBJECTIVE

To create the first European Academy of Andrology (EAA) guidelines on KS.

METHODS

An expert group of academicians appointed by the EAA generated a consensus guideline according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.

RESULTS

Clinical features are highly variable among patients with KS, although common characteristics are severely attenuated spermatogenesis and Leydig cell impairment, resulting in azoospermia and hypergonadotropic hypogonadism. In addition, various manifestations of neurocognitive and psychosocial phenotypes have been described as well as an increased prevalence of adverse cardiovascular, metabolic and bone-related conditions which might explain the increased morbidity/mortality in KS. Moreover, compared to the general male population, a higher prevalence of dental, coagulation and autoimmune disorders is likely to exist in patients with KS. Both genetic and epigenetic effects due to the supernumerary X chromosome as well as testosterone deficiency contribute to this pathological pattern. The majority of patients with KS is diagnosed during adulthood, but symptoms can already become obvious during infancy, childhood or adolescence. The paediatric and juvenile patients with KS require specific attention regarding their development and fertility.

CONCLUSION

These guidelines provide recommendations and suggestions to care for patients with KS in various developmental stages ranging from childhood and adolescence to adulthood. This advice is based on recent research data and respective evaluations as well as validations performed by a group of experts.

Testicular blood supply is altered in the 41,XXY* Klinefelter syndrome mouse model

Hypergonadotropic hypogonadism is a major feature of Klinefelter syndrome (KS), assumed to be caused by testicular hormone resistance. It was previously shown that intratesticular testosterone levels in vivo and Leydig cell function in vitro seem to be normal indicating other functional constraints. We hypothesized that impaired testicular vascularization/blood flow could be a co-factor to the observed hypergonadotropic hypogonadism. We evaluated the testicular vascular system by measuring blood vessel sizes during postnatal development and testis blood flow in adult 41,XX^Y* mice. Proportional distribution and size of blood vessels were analyzed during testicular development (1, 3, 5, 7, 10, 21 dpp, 15 wpp). While ratios of the vessel/testis area were different at 15 wpp only, a lower number of smaller and mid-sized blood vessels were detected in adult KS mice. For testicular blood flow determination we applied contrast enhanced ultrasound. Floating and reperfusion time for testicular blood flow was increased in 41,XX^Y* mice (floating: XY* 28.8 ± 1.69 s vs XX^Y* 44.6 ± 5.6 s, p = 0.0192; reperfusion XY* 19.7 ± 2.8 s vs XX^Y*: 29.9 ± 6.2 s, p = 0.0134), indicating a diminished blood supply. Our data strengthen the concept that an impaired vascularization either in conjunction or as a result of altered KS testicular architecture contributes to hormone resistance.

Effects of acute hCG stimulation on serum INSL3 and 25-OH vitamin D in Klinefelter syndrome

BACKGROUND

It has recently been suggested that the hypergonadotropic hypogonadism characterizing Klinefelter syndrome (KS) might not be due to a steroidogenic dysfunction per se, but mainly to an altered testosterone (T) secretion into the bloodstream. However, the Leydig cell functionality remains incompletely studied in KS, and new markers should be considered. Previous data indicated that chronic hCG stimulation influences the production of both insulin-like peptide 3 (INSL3) and 25-hydroxy-vitamin D (25-VD) in eugonadal men.

AIM OF THE STUDY

To evaluate INSL3 and 25-VD serum levels, as markers of Leydig cell functionality, in association with sex steroids, after an acute hCG test in a group of KS patients and healthy volunteers.

METHODS

A retrospective analysis of a prospective case-control clinical trial was carried out. KS patients (n = 11) and age-matched healthy controls (n = 11) provided a basal blood sample (V0) immediately followed by a single intramuscular injection of hCG 5000 IU. Blood samples were taken in the following five days (V1-V5).

RESULTS

At baseline, INSL3 was lower in KS patients compared with controls (P = .007). When adjusted for INSL3 levels, the production of steroids was similar between KS patients and controls. 25-VD was in the insufficient range both in KS patients and in controls and was not different (P = .064). Acute hCG stimulation increased neither INSL3 nor 25-VD in both KS patients and controls. In controls, an inverse correlation was detected between INSL3 levels and body mass index (P = .020) and waist circumference (P = .020).

CONCLUSIONS

INSL3 secretion is independent from steroidogenesis, and its production is mostly not influenced by acute hCG stimulation both in KS men and in controls. INSL3 serum levels should be considered as a marker of Leydig cell differentiation and numbers rather than steroidogenesis. 25-VD serum levels are also not increased by a single acute hCG administration, which was not able to restore the normal concentrations of 25-VD.

Integration and reanalysis of transcriptomics and methylomics data derived from blood and testis tissue of men with 47,XXY Klinefelter syndrome indicates the primary involvement of Sertoli cells in the testicular pathogenesis

Klinefelter syndrome (KS; 47,XXY) is the most common sex chromosomal anomaly and causes a multitude of symptoms. Often the most noticeable symptom is infertility caused by azoospermia with testicular histology showing hyalinization of tubules, germ cells loss, and Leydig cell hyperplasia. The germ cell loss begins early in life leading to partial hyalinization of the testis at puberty, but the mechanistic drivers behind this remain poorly understood. In this systematic review, we summarize the current knowledge on developmental changes in the cellularity of KS gonads supplemented by a comparative analysis of the fetal and adult gonadal transcriptome, and blood transcriptome and methylome of men with KS. We identified a high fraction of upregulated genes that escape X-chromosome inactivation, thus supporting previous hypotheses that these are the main drivers of the testicular phenotype in KS. Enrichment analysis showed overrepresentation of genes from the X- and Y-chromosome and testicular transcription factors. Furthermore, by re-evaluation of recent single cell RNA-sequencing data originating from adult KS testis, we found novel evidence that the Sertoli cell is the most affected cell type. Our results are consistent with disturbed cross-talk between somatic and germ cells in the KS testis, and with X-escapee genes acting as mediators.

41,XXY * male mice: An animal model for Klinefelter syndrome

Klinefelter syndrome (KS, 47,XXY) is the most frequent male chromosomal aneuploidy resulting in a highly heterogeneous clinical phenotype associated with hormonal dysbalance, increased rate of co-morbidities, and reduced lifespan. Two hallmarks of KS-affecting testicular functions are consistently observed: Hypergonadotropic hypogonadism and germ cell (GC) loss resulting in infertility. Although KS is being studied for decades, the underlying mechanisms for the observed pathophysiology are still unclear. Due to ethical restrictions, studies in humans are limited, and consequently, suitable animal models are needed to address the consequences of a supernumerary X chromosome. Mouse strains with comparable aneuploidies have been generated and yielded highly relevant insights into KS. We briefly describe the establishment of the KS mouse models, summarize the knowledge gained by their use, compare findings from the mouse models to those obtained in clinical studies, and also reflect on limitations of the currently used models derived from the B6Ei.Lt-Y* mouse strain, in which the Y chromosome is altered and its centromere position changed into a more distal location provoking meiotic non-disjunction. Breeding such as XY* males to XX females, the target 41,XX^Y *, and 41,XXY males are generated. Here, we summarize features of both models but report in particular findings from our 41,XX^Y * mice including some novel data on Sertoli cell characteristics.

Germ cell loss in Klinefelter syndrome: When and why?

Klinefelter syndrome (KS) is a quite common disorder with an incidence of 1-2 in 1,000 new-born males. Most patients are diagnosed in the light of a clinical checkup when consulting a fertility clinic with an unfulfilled child wish. Infertility in KS patients is caused by a massive germ cell loss, leading to azoospermia in more than 90% of the adult patients. Most seminiferous tubules in the adult KS testis are degenerated or hyalinized and testicular fibrosis can be observed, starting from puberty. However, focal spermatogenesis can be found in the testis of some patients. This offers the opportunity to extract spermatozoa from the testis by testicular sperm extraction (TESE). Nevertheless, TESE is only successful in about half of the KS adults seeking to father children. The reason for the germ cell loss remains unclear. To date, it is still debated whether the testicular tissue changes and the germ cell loss seen in KS is directly caused by an altered X-linked gene expression, the altered somatic environment, or a deficiency in the germ cells. In this review, we provide an overview of the current knowledge about the germ cell loss in KS patients.

Management of cardiovascular complications in Klinefelter syndrome patients

INTRODUCTION

Klinefelter syndrome (KS), also known as 47, XXY, shows increased mortality when compared with mortality rates among the general population. Cardiovascular, hemostatic, metabolic diseases are implicated. Moreover, cardiac congenital anomalies in KS can contribute to the increase in mortality.

AREAS COVERED

In this study, we have systematically reviewed the relationships between KS and the cardiovascular system and the management of cardiovascular complication. In summary, patients with KS display increased cardiovascular risk profile, characterized by increased prevalence of metabolic alterations including dyslipidemia, diabetes mellitus (DM), and abnormalities in biomarkers of cardiovascular disease. KS subjects are characterized by subclinical abnormalities in endothelial function and in left ventricular (LV) systolic and diastolic function, which - when associated with chronotropic incompetence - may negatively influence cardiopulmonary performance. Moreover, KS patients appear to be at a higher risk for cardiovascular disease, due to thromboembolic events with high prevalence of recurrent venous ulcers, venous insufficiency, recurrent venous and arterial thromboembolism leading to deep venous thrombosis or pulmonary embolism.

EXPERT OPINION

Considering the unequivocal finding of increased mortality of KS patients, we suggest a periodic cardiovascular follow up in specialized centers with multidisciplinary care teams that comprise endocrinologists and cardiologists dedicated to KS syndrome.

When does germ cell loss and fibrosis occur in patients with Klinefelter syndrome?

STUDY QUESTION

When does germ cell loss and fibrosis occur in patients with Klinefelter syndrome (KS)?

SUMMARY ANSWER

In KS, germ cell loss is not observed in testicular tissue from fetuses in the second semester of pregnancy but present at a prepubertal age when the testicular architecture is still normal, while fibrosis is highly present at an adolescent age.

WHAT IS KNOWN ALREADY

Most KS patients are azoospermic at adult age because of a massive germ cell loss. However, the timing when this germ cell loss starts is not known. It is assumed that germ cell loss increases at puberty. Therefore, testicular sperm extraction (TESE) at an adolescent age has been suggested to increase the chances of sperm retrieval at onset of spermatogenesis. However, recent data indicate that testicular biopsies from peripubertal KS patients contain only a few germ cells.

STUDY DESIGN, SIZE, DURATION

In this study, we give an update on fertility preservation in adolescent KS patients and evaluate whether fertility preservation would be beneficial at prepubertal age. The possibility of retrieving testicular spermatozoa by TESE was evaluated in adolescent and adult KS men. The presence of spermatogonia and the degree of fibrosis were also analysed in testicular biopsies from KS patients at different ages. The patients were divided into four age groups: foetal (n = 5), prepubertal (aged 4-7 years; n = 4), peripubertal (aged 12-16 years; n = 20) and adult (aged 18-41 years; n = 27) KS patients.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In peripubertal and adult KS patients, retrieval of spermatozoa was attempted by semen analysis after masturbation, vibrostimulation, electroejaculation or by TESE. MAGE-A4 immunohistochemistry was performed to evaluate the presence of germ cells in testicular biopsies from foetal, prepubertal, peripubertal and adult KS patients. Tissue morphology was evaluated by haematoxylin-periodic acid Schiff (H/PAS) staining.

MAIN RESULTS AND THE ROLE OF CHANCE

Testicular spermatozoa were collected by TESE in 48.1% of the adult KS patients, while spermatozoa were recovered after TESE in only one peripubertal patient (5.0%). Germ cells were detectable in testicular biopsies from 21% of adult men for whom no spermatozoa could be retrieved by TESE and in 31.5% of peripubertal KS boys. Very small numbers of spermatogonia (0.03-0.06 spermatogonia/tubule) were detected in three out of four (75%) prepubertal patients. At a foetal age, the number of germ cells was similar for KS and control samples. Increased signs of fibrosis were not present at foetal and prepubertal ages, but peripubertal and adult KS patients showed high levels of fibrosis.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Only four prepubertal biopsies were included in this study, but they all showed a very low germ cell number. A high variability in the number of spermatogonia per mm2 was observed in the limited (n = 5) number of foetal biopsies. However, testicular biopsies from prepubertal and foetal Klinefelter patients are difficult to obtain.

WIDER IMPLICATIONS OF THE FINDINGS

Testicular tissue banking at a prepubertal age has been suggested as a potential method for fertility preservation in early diagnosed KS boys. However, our results show that a reduction in germ cell number has already taken place in childhood. Therefore, offering testicular tissue banking in young KS boys to prevent subsequent sterility might be a questionable strategy. However, this should be confirmed in a larger study population.

STUDY FUNDING/COMPETING INTEREST(S)

This project was funded by the scientific Fund Willy Gepts from the UZ Brussel (D.V.S., J.D.S.), grants from the Vrije Universiteit Brussel (E.G.) and a Methusalem grant (K.S.). D.V.S is a post-doctoral fellow of the Fonds Wetenschappelijk Onderzoek (FWO; 12M2815N). No conflict of interest is declared.

Subcutaneous Leydig Stem Cell Autograft: A Promising Strategy to Increase Serum Testosterone

Exogenous testosterone therapy can be used to treat testosterone deficiency; however, it has several adverse effects including infertility due to negative feedback on the hypothalamic-pituitary-gonadal (HPG) axis. Leydig stem cell (LSC) transplantation could provide a new strategy for treating testosterone deficiency, but clinical translatability of injecting stem cells inside the testis is not feasible. Here, we explore the feasibility of subcutaneously autografting LSCs in combination with Sertoli and myoid cells to increase testosterone. We also studied whether the grafted LSCs can be regulated by the HPG axis and the molecular mechanism behind this regulation. LSCs were isolated from the testes of 12-week-old C57BL/6 mice, and subcutaneously autografted in combination with Sertoli cells and myoid cells. We found that LSCs alone were incapable of self-renewal and differentiation. However, in combination with Sertoli cells and myoid cells, LSCs underwent self-renewal as well as differentiation into mature Leydig cells. As a result, the recipient mice that received the LSC autograft showed testosterone production with preserved luteinizing hormone. We found that testosterone production from the autograft was regulated by hedgehog (HH) signaling. Gain of function and loss of function study confirmed that Desert HH (DHH) agonist increased and DHH antagonist decreased testosterone production from autograft. This study is the first to demonstrate that LSCs, when autografted subcutaneously in combination with Sertoli cells and myoid cells, can increase testosterone production. Therefore, LSC autograft may provide a new treatment for testosterone deficiency while simultaneously preserving the HPG axis. Stem Cells Translational Medicine 2019;8:58-65.

Klinefelter syndrome: more than hypogonadism

Klinefelter syndrome (KS) is the most frequent chromosome disorder in males (1:650 newborn males), defined by 47,XXY karyotype. The classical phenotype is that of a tall male with relatively long legs, small, firm testes and gynecomastia. Azoospermia and infertility are almost inevitably present, but may be overcome by TESE and ICSI. Nevertheless, a broad spectrum of phenotypes has been described and more than 70% of the actually existing KS men may remain undiagnosed throughout their lifespan. Accordingly, hypogonadism is usually not evident until early adulthood and progresses with ageing. KS patients present a series of comorbidities that increase morbidity and mortality by 40%. Such disturbances are the impaired metabolic profile (obesity, dyslipidemia, insulin resistance) and a tendency to thrombosis, which all favor cardiovascular disease. They also present susceptibility for specific neoplasias (breast cancer, extragonadal germ cell tumors), autoimmune diseases as well as osteoporosis and bone fractures. Moreover, KS has been associated with verbal processing and attention deficits as well as social skill impairments, leading KS individuals to academic and professional achievements inferior to those of their peers of comparable socio-economic status. Nevertheless, the majority fall within the average range regarding their intellectual abilities and adaptive functioning. Testosterone replacement therapy (TRT) is the mainstay of treatment in hypogonadal KS patients; however, randomized trials are needed to determine optimal therapeutic regimens and follow-up schedules.

Klinefelter Syndrome: Integrating Genetics, Neuropsychology, and Endocrinology

Although first identified over 70 years ago, Klinefelter syndrome (KS) continues to pose substantial diagnostic challenges, as many patients are still misdiagnosed, or remain undiagnosed. In fact, as few as 25% of patients with KS are accurately diagnosed and most of these diagnoses are not made until adulthood. Classic characteristics of KS include small testes, infertility, hypergonadothropic hypogonadism, and cognitive impairment. However, the pathophysiology behind KS is not well understood, although genetic effects are also thought to play a role. For example, recent developments in genetics and genomics point to a fundamental change in our understanding of KS, with global epigenetic and RNA expression changes playing a central role for the phenotype. KS is also associated with more general health markers, including higher morbidity and mortality rates and lower socioeconomic status (which likely affect both morbidity and mortality). In addition, hypogonadism is associated with greater risk of metabolic syndrome, type 2 diabetes, cardiovascular disease, breast cancer, and extragonadal germ cell tumors. Medical treatment typically focuses on testosterone replacement therapy (TRT), although the effects of this therapy have not been studied rigorously, and future studies need to evaluate the effects of TRT on metabolic risk and neurocognitive outcomes. This review presents a comprehensive interdisciplinary examination of recent developments in genetic, endocrine, and neurocognitive science, including the study of animal models. It provides a number of recommendations for improving the effectiveness of research and clinical practice, including neonatal KS screening programs, and a multidisciplinary approach to KS treatment from childhood until senescence.

Low testosterone in ApoE/LDL receptor double-knockout mice is associated with rarefied testicular capillaries together with fewer and smaller Leydig cells

The testis as a site for atherosclerotic changes has so far attracted little attention. We used the apolipoprotein E (ApoE)/low density lipoprotein (LDL) receptor deficient mouse model (KO) for atherosclerosis (20, 40, 60 and 87-week-old) to investigate whether Leydig cells or the capillary network are responsible for reduced serum testosterone levels previously observed in extreme ages of this model. In KO mice, overall testosterone levels were reduced whereas the adrenal gland-specific corticosterone was increased excluding a general defect of steroid hormone production. In addition to micro-CT investigations for bigger vessels, stereology revealed a reduction of capillary length, volume and surface area suggesting capillary rarefaction as a factor for diminished testosterone. Stereological analyses of interstitial cells demonstrated significantly reduced Leydig cell numbers and size. These structural changes in the testis occurred on an inflammatory background revealed by qPCR. Reduced litter size of the KO mice suggests hypo- or infertility as a consequence of the testicular defects. Our data suggest reduced testosterone levels in this atherosclerosis model might be explained by both, rarefication of the capillary network and reduced Leydig cell number and size. Thus, this study calls for specific treatment of male infertility induced by microvascular damage through hypercholesterolemia and atherosclerosis.

Aberrant ocular architecture and function in patients with Klinefelter syndrome

Klinefelter Syndrome (KS), the most common chromosomal disorder in men (47,XXY), is associated with numerous comorbidities. Based on a number of isolated case reports, we performed the first systematic and comprehensive evaluation of eye health in KS patients with a focus on ocular structure and vascularization. Twenty-one KS patients and 26 male and 38 female controls underwent a variety of non-invasive examinations investigating ocular morphology (examination of retinal thickness, optic nerve head, and cornea) and function (visual field testing and quantification of ocular vessel density by optical coherence tomography angiography). In comparison to healthy controls, KS patients exhibited a smaller foveal avascular zone and a decreased retinal thickness due to a drastically thinner outer nuclear layer. The cornea of KS patients showed a decreased peripheral thickness and volume. In perimetry evaluation, KS patients required brighter stimuli and gave more irregular values. KS patients show an ocular phenotype including morphological and functional features, which is very likely caused by the supernumerary X chromosome. Thus, KS should not be limited to infertility, endocrine dysfunction, neurocognitive and psychosocial comorbidities. Defining an aberrant ocular morphology and function, awareness for possible eye problems should be raised.

Prevalence of small testicular hyperechogenic foci in subgroups of 382 non-vasectomized, azoospermic men: a retrospective cohort study

Testicular hyperechogenic foci (THF) are associated with Klinefelter's syndrome, cryptorchidism, infertility, and testicular germ cell neoplasia. The aims of the study were to evaluate THF in relation to etiology of azoospermia and to Sertoli cell dysfunction. The structures inside the scrotum of consecutive non‐vasectomized, azoospermic were examined by ultrasonography, and hormone (FSH, LH, testosterone, and prolactin), and genetic analyses (karyotype, Y microdeletions, and CFTR mutations) were performed. At testicular ultrasonography, patients were graduated into: pronounced THF (>7 THF per transducer field), distributed universally (uTHF) or collected in plaques (pTHF), borderline THF (bTHF; 3–7 THF per transducer field), or no THF (<3 THF per transducer field). Diagnostic testicular biopsy was taken open or with TruCut needle (14G). THF status was sufficiently described in 382 of 449 potential participants, and testicular histology was available in 300 cases. Presence of ultrasonographically detectable THF was compared to presence of testicular microlithiasis (TM) detected histologically. Sertoli cell dysfunction was investigated in a subgroup using a three‐stage immunoperoxidase technique for detection of cytokeratin‐18 (CK‐18). The prevalence of THF was 13.4%. uTHF was found in 11 men (2.9%), the pattern was bilateral in four while other four had bTHF in the other testis. pTHF was detected in eight cases (2.1%), and except for one case with Klinefelter's syndrome, pTHF was in all cases occurring unilaterally. bTHF was detected in 32 cases (8.4%), bilaterally in 17 (53%). Pronounced THF was significantly associated with testicular malignancy. CK‐18 was detected in more azoospermic men with sperm production in ≤50% seminiferous tubules than in azoospermic men with spermatogenesis in ≥90% of seminiferous tubules and normal controls (p < 0.05). Unfortunately, TM detected histologically was not detected in any patient expressing THF, and neither THF nor TM was detected in any of the patients examined for CK‐18. Sertoli cell dysfunction was not associated with testicular microlithiasis or hyperechogenic foci.

Human chorionic gonadotropin stimulation gives evidence of differences in testicular steroidogenesis in Klinefelter syndrome, as assessed by liquid chromatography-tandem mass spectrometry

BACKGROUND

Men with Klinefelter syndrome (KS) show hypergonadotropic hypogonadism, but the pathogenesis of hypotestosteronemia remains unclear. Testicular steroidogenesis in KS men was evaluated over three decades ago after human chorionic gonadotropin (hCG) stimulation, but inconclusive results were obtained. Intriguingly, some recent studies show increased intratesticular testosterone concentrations in men with KS.

OBJECTIVE

To analyze serum steroid profile, as a proxy of testicular steroidogenesis, after hCG stimulation in KS compared with control men.

DESIGN

A prospective, longitudinal, case-control, clinical trial.

METHODS

Thirteen KS patients (36±9 years) not receiving testosterone (TS) replacement therapy and 12 eugonadic controls (32±8 years) were enrolled. Serum steroids were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) at baseline and for five consecutive days after intramuscular injection of 5000IU hCG.

RESULTS

Progesterone (P), 17-hydroxyprogesterone (17OHP), TS, and estradiol (E2) showed a significant increase (P<0.001) after hCG stimulation in both groups. On the contrary, androstenedione (AS) and dehydroepiandrosterone did not increase after hCG stimulation. The 17OHP/P ratio increased in both groups (P<0.001), the TS/AS ratio (17β-hydroxysteroid dehydrogenase type 3 (17βHSD3) activity) did not increase after hCG in any group, and the E2/TS ratio (aromatase activity) increased significantly in both groups (P=0.009 in KS and P<0.001 in controls). Luteinizing hormone decreased after hCG in both groups (P=0.014 in KS and P<0.001 in controls), whereas follicle-stimulating hormone decreased only in control men (P<0.001).

CONCLUSION

This study demonstrates for the first time using LC-MS/MS that Leydig cells of KS men are able to respond to hCG stimulation and that the first steps of steroidogenesis are fully functional. However, the TS production in KS men is impaired, possibly related to reduced hydroxysteroid deydrogenase activity due to an unfavorable intratesticular metabolic state.

Spermatogenesis in humans and its affecting factors

Spermatogenesis is an extraordinary complex process. The differentiation of spermatogonia into spermatozoa requires the participation of several cell types, hormones, paracrine factors, genes and epigenetic regulators. Recent researches in animals and humans have furthered our understanding of the male gamete differentiation, and led to clinical tools for the better management of male infertility. There is still much to be learned about this intricate process. In this review, the critical steps of human spermatogenesis are discussed together with its main affecting factors.

Testis Development and Fertility Potential in Boys with Klinefelter Syndrome

Klinefelter syndrome (KS) is the leading genetic cause of primary hypogonadism and infertility in men. The clinical phenotype has expanded beyond the original description of infertility, small testes, and gynecomastia. Animal models, epidemiologic studies, and clinical research of male subjects with KS throughout the lifespan have allowed the better characterization of the variable phenotype of this condition. This review provides an overview on what is known of the epidemiology, clinical features, and pathophysiology of KS, followed by a more focused discussion of testicular development and the clinical management of hypogonadism and fertility in boys and men with KS.

Testicular Sperm Sampling by Subcapsular Orchiectomy in Klinefelter Patients: A New Simplified Treatment Approach

OBJECTIVE

To evaluate subcapsular orchiectomy as a method to retrieve spermatozoa from minute testicular foci in men with Klinefelter syndrome (KS).

METHODS

Fourteen men with KS were consecutively recruited to unilateral subcapsular orchiectomy. Testicular tissue was dissected mechanically and enzymatically to identify possible sperm. Previous testosterone replacement therapy was interrupted for 10 months (range: 9-12 months) to minimize a possible effect on the spermatogenesis. Two men with high estrogen/testosterone ratios were treated with aromatase inhibitor (letrozol, 2.5 mg/d for 3 months) before operation.

RESULTS

Testicular sperm were detected in 5 of 14 KS men giving an overall success rate of 36%. The success rate was 50% (5 of 10 men) after exclusion of the 4 men previous treated with androgen substitution. So far, 3 (21%) clinical pregnancies and 2 live births or ongoing pregnancies (14%) have been obtained. Testicular sperm could not be detected in the 2 men treated with aromatase inhibitor before operation. The maximum operative time was 20 minutes, and none had surgical complications such as pain, fever, or hematomas. The mean testosterone level, measured 1-4 months after orchiectomy, decreased to 72% (7.9 ± 2.4 nmol/L) of the preoperative level.

CONCLUSION

Subcapsular orchiectomy appears to be easy and quick compared with conventional microtesticular sperm extraction. However, in this pilot study, it has not been possible to demonstrate pregnancy and live birth rates as high as that reported with microtesticular sperm extraction, and further studies are needed before the procedure should be used routinely for sperm retrieval in patients with KS.

Deregulation of sertoli and leydig cells function in patients with Klinefelter syndrome as evidenced by testis transcriptome analysis

Background

Klinefelter Syndrome (KS) is the most common abnormality of sex chromosomes (47,XXY) and represents the first genetic cause of male infertility. Mechanisms leading to KS testis degeneration are still not completely defined but considered to be mainly the result of germ cells loss. In order to unravel the molecular basis of global testis dysfunction in KS patients, we performed a transcriptome analysis on testis biopsies obtained from 6 azoospermic non-mosaic KS patients and 3 control subjects.

Results

The analysis found that, compared to controls, KS patients showed the differential up- and down-expression of 656 and 247 transcripts. The large majority of the deregulated transcripts were expressed by Sertoli cells (SCs) and Leydig cells (LCs). Functional analysis of the deregulated transcripts indicated changes of genes involved in cell death, inflammatory response, lipid metabolism, steroidogenesis, blood-testis-barrier formation and maintenance, as well as spermatogenesis failure.

Conclusions

Taken together, present data highlight the modulation of hundreds of genes in the somatic components of KS patient testis. The increased LCs steroidogenic function together with the impairment of inflammatory pathways and BTB structure, result in increased apoptosis. These findings may represent a critical roadmap for therapeutic intervention and prevention of KS-related testis failure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1356-0) contains supplementary material, which is available to authorized users.

The FSHB -211G>T variant attenuates serum FSH levels in the supraphysiological gonadotropin setting of Klinefelter syndrome

Klinefelter syndrome (47, XXY) is the most frequent genetic cause of male infertility and individuals share the endocrine hallmark of hypergonadotropic hypogonadism. Single-nucleotide polymorphisms located within the FSHB/FSHR gene were recently shown to impact serum follicle-stimulating hormone (FSH) levels and other reproductive parameters in men. The objective of this study was to analyse the effect of FSHB-211G>T (c.-280G>T, rs10835638) as well as FSHR c.2039G>A (rs6166) and FSHR c.-29G>A (rs1394205) on endocrine and reproductive parameters in untreated and testosterone-treated Klinefelter patients. Patients were retrospectively selected from the clientele attending a university-based andrology centre. A total of 309 non-mosaic Klinefelter individuals between 18 and 65 years were included and genotyped for the variants by TaqMan assays. The untreated group comprised 248 men, in which the FSHB -211G>T allele was significantly associated with the reduced serum follicle-stimulating hormone levels (-6.5 U/l per T allele, P=1.3 × 10(-3)). Testosterone treatment (n=150) abolished the observed association. When analysing patients before and under testosterone treatment (n=89), gonadotropin levels were similarly suppressed independently of the FSHB genotype. The FSHR polymorphisms did not exhibit any significant influence in any group, neither on the endocrine nor reproductive parameters. In conclusion, a hypergonadotropic setting such as Klinefelter syndrome does not mask the FSHB -211G>T genotype effects on the follicle-stimulating hormone serum levels. The impact was indeed more pronounced compared with normal or infertile men, whereas gonadotropin suppression under testosterone treatment seems to be independent of the genotype. Thus, the FSHB -211G>T genotype is a key determinant in the regulation of gonadotropins in different reproductive-endocrine pathopyhsiologies.