Altered expression and localization of estrogen receptors alpha and beta in the testes of a cryptorchid rat model

CYP19 and ESR2 polymorphisms as potential culprits in cryptorchidism

INTRODUCTION

Cryptorchidism impairs sperm development and increases the risk of infertility and testicular cancer. Estrogen signalling is critical for proper descent of the testicles, and hormonal imbalances play a role in cryptorchidism. CYP19, also known as aromatase, encodes an enzyme that converts testosterone, a male sex hormone, into estradiol, the main form of estrogen. While estrogen receptors can be activated by estrogen, CYP19 plays an important role in regulating local estrogen levels in tissues such as the testes, as it affects cellular processes controlled by estrogen receptors.

OBJECTIVE

We aimed to investigate the relationship between polymorphisms in the CYP19 (rs2414096) and ESR2 (rs4986938) and susceptibility to cryptorchidism.

STUDY DESIGN

We genotyped CYP19 (rs2414096) and ESR2 (rs4986938) polymorphisms using PCR-RFLP in DNA isolated from blood samples of cryptorchid children (n = 41) and healthy controls (n = 42). The differences in genotype and allele frequencies between the cryptorchidism and control groups were calculated using the chi-square (χ2).

RESULTS

In cryptorchidism patients, genotypes (p < 0.05) and allele frequencies (p < 0.05) of CYP19 (rs2414096) and ESR2 (rs4986938) polymorphisms showed significant differences compared to controls. CYP19 (rs2414096) and ESR2 (rs4986938), the AA genotype and A allele frequency may be risk factors for cryptorchidism, while the GG genotype and G allele may be protective against cryptorchidism.

DISCUSSION

Our study provides compelling evidence for a significant association between polymorphisms in the CYP19 (rs2414096) and ESR2 (rs4986938) polymorphisms and cryptorchidism susceptibility. These findings extend previous research implicating genetic factors in testicular descent but go further by identifying specific polymorphisms associated with increased risk. While previous studies have suggested a role for estrogen imbalance in cryptorchidism, our results provide concrete genetic evidence supporting this hypothesis. The relatively small sample size necessitates replication in larger cohorts to further validate our findings. Additionally, functional studies are warranted to elucidate the precise mechanisms by which these genetic variants influence cryptorchidism risk. Despite these limitations, our results represent a significant step in unravelling the complex aetiology of this common birth defect.

CONCLUSION

Our findings show that polymorphisms in CYP19 (rs2414096) and ESR2 (rs4986938), which play a role in estrogen production, are significantly associated with cryptorchidism susceptibility, highlighting the potential role of estrogen pathway variations in testicular descent.

AZIN2 is associated with apoptosis of germ cells in undescended testis

Undescended testis (UDT), known as cryptorchidism (CRY), is a common congenital disorder in which one or both testicles do not descend normally into the scrotum. A unilateral UDT model was established by inducing UDT in mice through surgery. The results showed that the testis in the UDT model group was abnormal; the lumen of the seminiferous tubule was atrophic; apoptosis, necrosis and shedding were observed in many of the germ cells; the level of sex hormones was abnormal; and mature sperm was reduced. Subsequently, transcriptome sequencing was conducted on the testicular tissue of UDT model mice. Through analysis and verification of differential genes, AZIN2 was identified as playing a key role in the decline in male fertility caused by cryptorchidism. AZIN2 expression and spermine content was down-regulated in the testis of the UDT group. We then used a combination of hypoxanthine and xanthine to create a GC-1 cell damage model. In this model, AZIN2 expression and spermine content was down-regulated. When si-Azin2 transfected GC-1 cells, cell viability and proliferation were decreased. However, in the GC-1 cell damage model transfected with Azin2 over-expressed plasmid, AZIN2 expression and spermine content was up-regulated, reversing the cell damage caused by hypoxanthine and xanthine, and restoring the proliferation ability of GC-1 cells. These results indicate that in UDT, down-regulated AZIN2 expression is a factor in testicular damage. This discussion of the connection between AZIN2 and germ cells has important clinical significance as it provides an important reference for the diagnosis and treatment of cryptorchidism.

Loss of WNT4 in the gubernaculum causes unilateral cryptorchidism and fertility defects

Undescended testis (UDT) affects 6% of male births. Despite surgical correction, some men with unilateral UDT may experience infertility with the contralateral descended testis (CDT) showing no A-dark spermatogonia. To improve our understanding of the etiology of infertility in UDT, we generated a novel murine model of left unilateral UDT. Gubernaculum-specific Wnt4 knockout (KO) mice (Wnt4-cKO) were generated using retinoic acid receptor β2-cre mice and were found to have a smaller left-unilateral UDT. Wnt4-cKO mice with abdominal UDT had an increase in serum follicle-stimulating hormone and luteinizing hormone and an absence of germ cells in the undescended testicle. Wnt4-cKO mice with inguinal UDT had normal hormonal profiles, and 50% of these mice had no sperm in the left epididymis. Wnt4-cKO mice had fertility defects and produced 52% fewer litters and 78% fewer pups than control mice. Wnt4-cKO testes demonstrated increased expression of estrogen receptor α and SOX9, upregulation of female gonadal genes, and a decrease in male gonadal genes in both CDT and UDT. Several WNT4 variants were identified in boys with UDT. The presence of UDT and fertility defects in Wnt4-cKO mice highlights the crucial role of WNT4 in testicular development.

The Fate of Leydig Cells in Men with Spermatogenic Failure

The steroidogenic cells in the testicle, Leydig cells, located in the interstitial compartment, play a vital role in male reproductive tract development, maintenance of proper spermatogenesis, and overall male reproductive function. Therefore, their dysfunction can lead to all sorts of testicular pathologies. Spermatogenesis failure, manifested as azoospermia, is often associated with defective Leydig cell activity. Spermatogenic failure is the most severe form of male infertility, caused by disorders of the testicular parenchyma or testicular hormone imbalance. This review covers current progress in knowledge on Leydig cells origin, structure, and function, and focuses on recent advances in understanding how Leydig cells contribute to the impairment of spermatogenesis.

Immunohistochemical examination of androgen receptor and estrogen receptor alpha expressions in obstructive and non-obstructive azoospermia

In this study, the expression of the androgen receptor (AR) and estrogen receptor alpha (ERα) in testicular tissue of male patients with obstructive azoospermia (OA) and non-obstructive azoospermia (NOA) were evaluated by immunohistochemistry. NOA (n = 23) and OA (n = 21) groups were created according to clinical and laboratory archival records. Testicular sperm extraction tissue sections were evaluated according to Johnsen's tubular biopsy scoring (JTBS) method. ERα and AR immunostaining results were evaluated semiquantitatively. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and estradiol were analyzed. Serum FSH and LH concentrations were greater, and testosterone concentrations were lower than the normal values in the NOA group, whereas the OA group revealed normal hormonal values. Serum estradiol concentrations in groups were in the normal range. JTBSs were significantly lower in the NOA group. Decreased AR expression and increased ERα expression were observed in the NOA group compared to the OA group. This suggests that ERα and AR are expressed in Sertoli cells, Leydig cells, and myoid cells and are required for normal testicular function. Decreased expression of the AR and increased expression of ERα in the testis may negatively affect spermatogenesis.Abbreviations: AR: androgen receptor; ER: estrogen receptor; ERα: estrogen receptor alpha; FSH: follicle-stimulating hormone; JTBS: Johnsen's tubular biopsy scoring; LH: luteinizing hormone; NOA: non-obstructive azoospermia; OA: obstructive azoospermia; TESE: testicular sperm extraction.

The G-Protein-Coupled Membrane Estrogen Receptor Is Present in Horse Cryptorchid Testes and Mediates Downstream Pathways

Cryptorchidism in horses is a commonly occurring malformation. The molecular basis of this pathology is not fully known. In addition, the origins of high intratesticular estrogen levels in horses remain obscure. In order to investigate the role of the G-protein-coupled membrane estrogen receptor (GPER) and establish histological and biochemical cryptorchid testis status, healthy and cryptorchid horse testes were subjected to scanning electron microscopy analysis, histochemical staining for total protein (with naphthol blue black; NBB), acid content (with toluidine blue O; TBO), and polysaccharide content (with periodic acid-Schiff; PAS). The expression of GPER was analyzed by immunohistochemistry and Western blot. GPER-mediated intracellular cAMP and calcium (Ca2+) signaling were measured immunoenzymatically or colorimetrically. Our data revealed changes in the distribution of polysaccharide content but not the protein and acid content in the cryptorchid testis. Polysaccharides seemed to be partially translocated from the interstitial compartment to the seminiferous tubule compartment. Moreover, the markedly decreased expression of GPER and GPER downstream molecules, cAMP and Ca2+, suggests their potential role in testis pathology. Increased estrogen levels in cryptorchid conditions may be linked to disturbed GPER signaling. We postulate that GPER is a prominent key player in testis development and function and may be used as a new biomarker of horse testis in health and disease.

Differential abundances of AQP3 and AQP5 in reproductive tissues from dogs with and without cryptorchidism

Aquaporins (AQPs) are integral transmembrane proteins facilitating transport of water and small solutes, such as glycerol and urea, between cells. In male reproductive tracts, AQPs maintain a milieu conducive for sperm formation, maturation, and storage. The aim of this study was to clarify effects of testicular and epidydimal function on male fertility by investigating localisation and abundances of AQP3 and AQP5 in testes and epididymal segments from dogs with and without unilateral cryptorchidism. Immunohistochemistry results indicated AQP3 and AQP5 have different distribution patterns in reproductive tissues of dogs with and without unilateral cryptorchidism. The AQP3, an aquaglyceroprotein, is present in different germ and Sertoli cells in testis of dogs without cryptorchidism. The AQP5 protein was not detected in germ cells but was present in Sertoli and Leydig cells and in endothelia of blood vessels. In cryptorchid dogs, AQP3 was detected in early-developing germ and Sertoli cells, and AQP5 had a distribution pattern similar to testes of dogs without cryptorchidism. In the epididymis, AQP3 and AQP5 were localised in epithelial cells of dogs with and without cryptorchidism in a cell-specific manner. The AQP3 and AQP5 protein was in larger abundance in the gonads from dogs with and without cryptorchidism. In contrast, AQP3 and AQP5 abundance increased in each segment of the cryptorchid epididymis, likely as a compensatory mechanism associated with the pathologic condition. These results indicate involvement of AQP3 and AQP5 in spermatogenesis and sperm maturation. Results from the present study indicate dogs are a useful for comparative reproductive biology studies.

Estrogens and development of the rete testis, efferent ductules, epididymis and vas deferens

Estrogen has always been considered the female hormone and testosterone the male hormone. However, estrogen's presence in the testis and deleterious effects of estrogen treatment during development have been known for nearly 90 years, long before estrogen receptors (ESRs) were discovered. Eventually it was learned that testes actually synthesize high levels of estradiol (E2) and sequester high concentrations in the reproductive tract lumen, which seems contradictory to the overwhelming number of studies showing reproductive pathology following exogenous estrogen exposures. For too long, the developmental pathology of estrogen has dominated our thinking, even resulting in the "estrogen hypothesis" as related to the testicular dysgenesis syndrome. However, these early studies and the development of an Esr1 knockout mouse led to a deluge of research into estrogen's potential role in and disruption of development and function of the male reproductive system. What is new is that estrogen action in the male cannot be divorced from that of androgen. This paper presents what is known about components of the estrogen pathway, including its synthesis and target receptors, and the need to achieve a balance between androgen- and estrogen-action in male reproductive tract differentiation and adult functions. The review focuses on what is known regarding development of the male reproductive tract, from the rete testis to the vas deferens, and examines the expression of estrogen receptors and presence of aromatase in the male reproductive system, traces the evidence provided by estrogen-associated knockout and transgenic animal models and discusses the effects of fetal and postnatal exposures to estrogens. Hopefully, there will be enough here to stimulate discussions and new investigations of the androgen:estrogen balance that seems to be essential for development of the male reproductive tract.

Association between RNA-binding protein Ptbp2 and germ cell injury in an experimentally-induced unilateral cryptorchidism murine model

RNA binding protein polypyrimidine tract binding protein 2 (Ptbp2) as a key alternative splicing regulator for male germ cell development is well established. However, its expression levels and role in cryptorchidism testes tissues has not been explored. Additionally, the molecular mechanism of heat stress impacts the correct proliferation and differentiation of germ cells is unclear. To investigate whether changes in Ptbp2 expression are correlated with heat stress-induced germ cell injury in testicular tissue, we used a murine model of intraperitoneal cryptorchidism with surgical operation. Here we present compelling evidence that germ cells are severely damaged in mice with unilateral cryptorchidism, with non-obstructive azoospermia. And the Ptbp2 and Pgk2 mRNA levels were significantly decreased in parallel, leading us to conclude that the negative correlation between Ptbp2 levels and germ cell injury in unilateral cryptorchidism murine model. We hypothesize that Ptbp2 is susceptible to heat stress and its disruption has resulted in stability decline of germ cell transcripts Pgk2 mRNA, which consequently lead to germ cell injury in cryptorchidism testes. Thus, we confirm that Ptbp2 is an essential factor in heat stress-induced sperm cell injury and non-obstructive azoospermia.

Risk factors for cryptorchidism

Undescended testis - known as cryptorchidism - is one of the most common congenital abnormalities observed in boys, and is one of the few known risk factors for testicular cancer. The key factors that contribute to the occurrence of cryptorchidism remain elusive. Testicular descent is thought to occur during two hormonally-controlled phases in fetal development - between 8-15 weeks (the first phase of decent) and 25-35 weeks gestation (the second phase of descent); the failure of a testis to descend permanently is probably caused by disruptions to one or both of these phases, but the causes and mechanisms of such disruptions are still unclear. A broad range of putative risk factors have been evaluated in relation to the development of cryptorchidism but their plausibility is still in question. Consistent evidence of an association with cryptorchidism exists for only a few factors, and in those cases in which evidence seems unequivocal the factor is likely to be a surrogate for the true causal exposure. The relative importance of each risk factor could vary considerably between mother-son pairs depending on an array of genetic, maternal, placental and fetal factors - all of which could vary between regions. Thus, the role of causative factors in aetiology of cryptorchidism requires further research.

A allele of SNP12 in estrogen receptor 1 was a risk factor for cryptorchidism in Asians: a systematic review with meta-analysis and trial sequential analysis

OBJECTIVE

Some studies have been carried out to evaluate the association between SNP12 in estrogen receptor 1 and cryptorchidism, but the results remain inconsistent. We carried out a meta-analysis to explore the association between this polymorphism and cryptorchidism risk.

METHODS

All eligible studies were searched in PubMed, Web of Science, Embase and Cochrane Library. Pooled odds ratios, with 95 % confidence intervals, were assessed for the association using fixed- and random-effects models.

RESULTS

Overall, four case-control studies (363 cases, 415 controls) were included in the meta-analysis. No significant publication bias (P Begg = 0.308, P Egger = 0.288) was found. A allele of SNP12 in estrogen receptor 1 was protective factor to cryptorchidism in allele model, dominant genetic model and heterozygote comparison in Caucasians, but the result was turned out to be false positive by trial sequential analysis. However, A in allele model was risk factor to cryptorchidism in Asians (odds ratio 2.02, 95 % confidence interval 1.03-3.01, p = 0.946 for heterogeneity) and the result was turned out to be true positive by trial sequential analysis, even though there were merely two original studies.

CONCLUSIONS

The results of this meta-analysis suggest that A allele of SNP12 in estrogen receptor 1 may increase the risk of cryptorchidism in Asians. Meanwhile, further well-designed studies with large sample sizes are required to confirm the present findings, especially in Caucasians.

Differential expression of estrogen receptor α and progesterone receptor in the normal and cryptorchid testis of a dog

Descending of the testes is an important process for spermatogenesis and cryptorchidism is one of the most relevant genital defects in dogs. In a previous study, we observed abnormal morphology and proliferation of Sertoli cells in a cryptorchid testis. In the present study, we investigated the expression of estrogen and progesterone receptors in the normal and cryptorchid testis of a dog. Elective orchidectomy was performed on the dog's abdominal right testis (undescended, cryptorchid) and scrotal left testis (descended, normal). In the normal testis, estrogen receptor α immunoreactivity was detected in Leydig cells alone, while estrogen receptor α immunoreactivity in the cryptorchid testis was significantly prominent in the Sertoli cells as well. In addition, progesterone receptor immunoreactivity in the control testis was detected in the spermatids, but was not detected in the cryptorchid testis. This result suggests that unilateral cryptorchidism causes increases of estrogen receptor α expression in Sertoli cells.

Mast cells, estrogens, and cryptorchidism: A histological based review

If untreated, cryptorchidism leads to age dependent decreases in germ cell number (GCN) and testicular fibrosis. The pathophysiology of this process and its long-term effects on fertility are unclear. Mast cells are intricately involved in inflammation and fibrosis in a variety of organ systems. Their secretory products have mitogenic effects on fibroblasts and promote collagen deposition. Mast cell activation and migration are under the influence of estrogens and this interaction has been demonstrated in the testes in several animal models. Models of cryptorchidism have shown increased estrogen levels and expression of estrogen receptors in undescended testes compared to controls. Mast cell numbers have positively correlated with testicular fibrosis in human studies and decreased spermatogenesis as well. We found no human studies of mast cells in cryptorchid testes. However several animal models have investigated the effect of estrogens on mast cells and spermatogenesis in undescended testes. In this review we examine the possible links between estrogens, mast cells, and testicular fibrosis in cryptorchidism, focusing on histological studies.

Expression of estrogen receptors α and β in paratesticular tissues in boys operated on for unilateral cryptorchidism between the 1st and 4th years of life

BACKGROUND

The aim of this study was to assess the expression of estrogen receptors alpha and beta in paratesticular tissues in a group of boys with and without cryptorchidism, and evaluation of karyotypes, localization, morphology and the major length of the undescended testes.

MATERIAL/METHODS

Fifty boys (1-4 years old) with unilateral cryptorchidism were evaluated. Fifty healthy boys within the same age range, with inguinal hernia, served as a control group. Measurements concerning expression of ERalpha ERbeta receptors were preformed using monoclonal mouse antibodies against human receptor alpha and beta.

RESULTS

In the mesothelial layer, the expression of ERalpha was higher in the patients group with undescended testes and it was statistically significant (p=0.04). There was no difference in the expression of ERbeta in this layer between groups. In the stromal cell layer there was statistically significant higher expression of ERbeta (p<0.05) in the group of patients with undescended testes.

CONCLUSIONS

There was no difference between expressions of ERalpha in stromal cell layer. In the endothelial layer there was no difference in expression of ERalpha and ERbeta. In the smooth muscle layer there was no expression of ERalpha in either group. The expression of ERbeta in the smooth muscle layer was nearly identical in both groups. Undescended testes were generally found in the superficial inguinal pouch (n=46). The major lengths of the undescended testes were smaller in comparison to the testes positioned normally. In 9 of the cases the testes had different shape, and turgor deficit, and epididymides were smaller, dysplastic and separated from the testis.