INSL3 and AMH in patients with previously congenital or acquired undescended testes

Diagnoses and Treatment of Acquired Undescended Testes: A Review

Acquired undescended testes were once considered a sporadic disease. In recent years, reports suggest that they are not uncommon, with an incidence rate about 3 times that of congenital undescended testes. The etiology of acquired undescended testes remains inconclusive, clinical diagnostic standards are unclear, and treatment approaches are still controversial. There is ongoing debate about the mechanism of testicular ascent. The prevailing view is that acquired undescended testes occur due to the partial absorption of the gubernaculum, which forms part of the parietal peritoneum. The residual gubernacular fibers continuously pull on the spermatic cord, preventing the spermatic cord from elongating proportionately to somatic growth, leading to a re-ascent of the testis. Acquired undescended testes may increase the risk of testicular cancer, but this is still debated. The preferred treatment method is also controversial. However, surgical fixation has an immediate effect; no studies have proven that early surgery improves fertility in patients. The etiology of acquired undescended testes is closely related to the continuous pull of the residual gubernacular fibers on the spermatic cord, which prevents the cord from extending proportionately to body growth. There are no clear diagnostic standards for acquired undescended testes yet, and spontaneous descent is possible, so testicular fixation surgery may not be the preferred treatment method.

Anti-Müllerian hormone, testicular descent and cryptorchidism

Anti-Müllerian hormone (AMH) is a Sertoli cell-secreted glycoprotein involved in male fetal sex differentiation: it provokes the regression of Müllerian ducts, which otherwise give rise to the Fallopian tubes, the uterus and the upper part of the vagina. In the first trimester of fetal life, AMH is expressed independently of gonadotropins, whereas from the second trimester onwards AMH testicular production is stimulated by FSH and oestrogens; at puberty, AMH expression is inhibited by androgens. AMH has also been suggested to participate in testicular descent during fetal life, but its role remains unclear. Serum AMH is a well-recognized biomarker of testicular function from birth to the first stages of puberty. Especially in boys with nonpalpable gonads, serum AMH is the most useful marker of the existence of testicular tissue. In boys with cryptorchidism, serum AMH levels reflect the mass of functional Sertoli cells: they are lower in patients with bilateral than in those with unilateral cryptorchidism. Interestingly, serum AMH increases after testis relocation to the scrotum, suggesting that the ectopic position result in testicular dysfunction, which may be at least partially reversible. In boys with cryptorchidism associated with micropenis, low AMH and FSH are indicative of central hypogonadism, and serum AMH is a good marker of effective FSH treatment. In patients with cryptorchidism in the context of disorders of sex development, low serum AMH is suggestive of gonadal dysgenesis, whereas normal or high AMH is found in patients with isolated androgen synthesis defects or with androgen insensitivity. In syndromic disorders, assessment of serum AMH has shown that Sertoli cell function is preserved in boys with Klinefelter syndrome until mid-puberty, while it is affected in patients with Noonan, Prader-Willi or Down syndromes.

New Insights into the Role of INSL-3 in the Development of Cryptorchidism

Cryptorchidism, defined as the failure of at least one or both testicles to descend into the scrotal pouches, is the most frequent (1.6-9% at birth, 1/20 males at birth) congenital anomaly encountered in newborn males, resulting in one of the most frequent causes of non-obstructive azoospermia in men. Similar to other congenital malformations, cryptorchidism is thought to be caused by endocrine and genetic factors, combined with maternal and environmental influences. The etiology of cryptorchidism is unknown, as it involves complex mechanisms aiming to control the testicular development and descent from their initial intra-abdominal location in scrotal pouches. The implication of insulin-like 3 (INSL-3) associated with its receptor (LGR8) is critical. Genetic analysis discloses functionally deleterious mutations in INSL3 and GREAT/LGR8 genes. In this literature review, we discuss and analyze the implication of INSL3 and the INSL3/LGR8 mutation in the occurrence of cryptorchidism in both human and animal models.

Association of antimullerian hormone with the size of the appendix testis, the androgen and estrogen receptors and their expression in the appendix testis, in congenital cryptorchidism

OBJECTIVES

Antimullerian hormone (AMH) causes regression of the mullerian ducts in the male fetus. The appendix testis (AT) is a vestigial remnant of mullerian duct origin, containing both androgen (AR) and estrogen (ER) receptors. The role of both AMH and AT in testicular descent is yet to be studied. We investigated the possible association of AMH with AT size, the AR and ER, and their expression in the AT, in congenital cryptorchidism.

METHODS

A total of 26 patients with congenital unilateral cryptorchidism and 26 controls with orthotopic testes were investigated, and 21 ATs were identified in each group. AMH and insulin-like three hormone (INSL3) concentrations were measured with spectrophotometry. AR and ER receptor expression was assessed with immunohistochemistry using monoclonal antibodies R441 for AR and MAB463 for ER. For the estimation of receptor expression, the Allred Score method was used.

RESULTS

AMH concentrations did not present significant differences between patients with congenital cryptorchidism and the controls. Also, no correlation was found between AMH, INSL3, and AT length. Allred scores did not present significant differences. However, expression percentiles and intensity for both receptors presented significant differences. Three children with cryptorchidism and the highest AMH levels also had the highest estrogen receptor scores in the AT.

CONCLUSIONS

No association was found between AMH and the studied major parameters. However, higher AMH concentrations, in combination with higher estrogen receptor scores in the AT, may play a role in cryptorchidism in some children. Larger population samples are needed to verify this observation.

Multicenter Analysis of Acquired Undescended Testis and Its Impact on the Timing of Orchidopexy

OBJECTIVE

To assess whether late orchidopexy for undescended testis represents delayed treatment of primary undescended testis or later-occurring acquired undescended testis.

STUDY DESIGN

We examined boys undergoing orchidopexy for cryptorchidism regarding age at surgery and entity of undescended testis. We characterized differences between primary undescended testis and acquired undescended testis and evaluated the knowledge regarding the diagnosis and management of acquired undescended testis among practicing physicians. We conducted an observational study using a mixed-method multicenter cross-sectional design. A total of 310 consecutive boys undergoing orchidopexy for undescended testis at 6 pediatric medical centers in Germany between April 2016 and June 2018 were investigated regarding testicular position at birth and age at surgery. In addition, a survey on acquired undescended testis management was carried out in 1017 multidisciplinary physicians and final-year medical students.

RESULTS

Only 13% of all patients were operated on in their first year of life. Among patients with known previous testicular position (67%), primary undescended testis (n = 103) and acquired undescended testis (n = 104) were equally frequent. More than one-half (56%) of orchidopexies performed after the first year of life were due to acquired undescended testis. Remarkably, only 15% of physicians considered acquired undescended testis as an indication for late surgery.

CONCLUSIONS

Acquired undescended testis is more common than previously perceived and accounts for a significant proportion of "late" orchidopexies in patients with undescended testis. Acquired undescended testis needs to be better recognized in clinical practice and screening should continue in older children with previously descended testes.

TRIAL REGISTRATION

German Clinical Trials Registry: DRKS00015903.

Biomarcadores de hipogonadismo masculino en la infancia y la adolescencia

El eje hipotálamo-hipófiso-testicular es activo en la vida fetal y durante los primeros meses de la vida posnatal: la hipófisis secreta hormona luteinizante (LH) y folículo-estimulante (FSH), mientras que el testículo produce testosterona y factor insulino-símil 3 (INSL3) en las células de Leydig y hormona anti-Mülleriana (AMH) e inhibina B en las células de Sertoli. En la infancia, los niveles séricos de gonadotrofinas, testosterona y factor INSL3 disminuyen a valores prácticamente indetectables, pero los de AMH e inhibina B permanecen altos. En la pubertad, se reactivan las gonadotrofinas y la producción de testosterona e INSL3, aumenta la inhibina y disminuye la AMH, como signo de maduración de la célula de Sertoli. Sobre la base del conocimiento de la fisiología del desarrollo del eje, es posible utilizar clínicamente estos biomarcadores para interpretar la fisiopatología y diagnosticar las diferentes formas de hipogonadismo que pueden presentarse en la infancia y la adolescencia.

Biomarkers of male hypogonadism in childhood and adolescence

Objectives

The objective of this review was to characterize the use of biomarkers of male hypogonadism in childhood and adolescence.

Contents

The hypothalamic-pituitary-gonadal (HPG) axis is active during fetal life and over the first months of postnatal life. The pituitary gland secretes follicle stimulating hormone (FSH) and luteinizing hormone (LH), whereas the testes induce Leydig cells to produce testosterone and insulin-like factor 3 (INSL), and drive Sertoli cells to secrete anti-Müllerian hormone (AMH) and inhibin B. During childhood, serum levels of gonadotropins, testosterone and insulin-like 3 (INSL3) decline to undetectable levels, whereas levels of AMH and inhibin B remain high. During puberty, the production of gonadotropins, testosterone, and INSL3 is reactivated, inhibin B increases, and AMH decreases as a sign of Sertoli cell maturation.

Summary and outlook

Based on our knowledge of the developmental physiology of the HPG axis, these biomarkers can be used in clinical practice to interpret the physiopathology of hypogonadism. Additionally, these markers can have diagnostic value in different forms of hypogonadism that may appear during childhood and adolescence.

Safety of standardised treatments for haematologic malignancies as regards to testicular endocrine function in children and teenagers

STUDY QUESTION

Does standardised treatments used in children and adolescents with haematologic malignancies, including acute lymphoblastic (ALL) or myeloid leukaemia (AML) and non-Hodgkin lymphoma (NHL), affect endocrine function of the developing testes?

SUMMARY ANSWER

Therapy of haematologic malignancies do not provoke an overt damage of Sertoli and Leydig cell populations, as revealed by normal levels of anti-Müllerian hormone (AMH) and testosterone, but a mild primary testicular dysfunction may be observed, compensated by moderate gonadotropin elevation, during pubertal development.

WHAT IS KNOWN ALREADY

Evidence exists on the deleterious effect that chemotherapy and radiotherapy have on germ cells, and some attention has been given to the effects on Leydig and Sertoli cells of the adult gonads, but information is virtually non-existent on the effects of oncologic treatment on testicular somatic cell components during childhood and adolescence.

STUDY DESIGN, SIZE, DURATION

A retrospective, analytical, observational study included 97 boys with haematological malignancies followed at two tertiary paediatric public hospitals in Buenos Aires, Argentina, between 2002 and 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Clinical records of males aged 1-18 years, referred with the diagnoses of ALL, AML or NHL for the assessment of gonadal function, were eligible. We assessed serum levels of AMH and FSH as biomarkers of Sertoli cell endocrine function and testosterone and LH as biomarkers of Leydig cell function.

MAIN RESULTS AND THE ROLE OF CHANCE

All hormone levels were normal in the large majority of patients until early pubertal development. From Tanner stage G3 onwards, while serum AMH and testosterone kept within the normal ranges, gonadotropins reached mildly to moderately elevated values in up to 35.9% of the cases, indicating a compensated Sertoli and/or Leydig cell dysfunction, which generally did not require hormone replacement therapy.

LIMITATIONS, REASONS FOR CAUTION

Serum inhibin B determination and semen analysis were not available for most patients; therefore, we could not conclude on potential fertility impairment or identify whether primary Sertoli cell dysfunction resulted in secondary depleted spermatogenesis or whether primary germ cell damage impacted Sertoli cell function.

WIDER IMPLICATIONS OF THE FINDINGS

The regimens used in the treatment of boys and adolescents with ALL, AML or NHL in the past two decades seem relatively safe for endocrine testicular function; nonetheless, a mild primary testicular endocrine dysfunction may be observed, usually compensated by slightly elevated gonadotropin secretion by the pituitary in adolescents, and not requiring hormone replacement therapy. No clinically relevant risk factor, such as severity of the disease or treatment protocol, could be identified in association with the compensated endocrine dysfunction.

STUDY FUNDING/COMPETING INTEREST(S)

This work was partially funded by grants PIP 11220130100687 of Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and PICT 2016-0993 of Fondo para la Investigación Científica y Tecnológica (FONCYT), Argentina. R.A.R., R.P.G. and P.B. have received honoraria from CONICET (Argentina) for technology services using the AMH ELISA. L.A.A. is part-time employee of CSL Behring Argentina. The other authors have no conflicts of interest to disclose.

Novel combined insulin-like 3 variations of a single nucleotide in cryptorchidism

Background Insulin-like 3 hormone (INSL3) is involved in the process of testicular descent, and has been thoroughly studied in cryptorchidism. However, INSL3 allelic variations found in the human genome were heterozygous and only a few of them were found exclusively in patients with cryptorchidism. Under this perspective, we aimed to study the presence of INSL3 allelic variations in a cohort of patients with cryptorchidism and to estimate their potential consequences. Methods Blood samples were collected from 46 male patients with non-syndromic cryptorchidism and from 43 age-matched controls. DNA extraction and polymerase chain reaction (PCR) were performed for exons 1 and 2 of the INSL3 gene in all subjects. Sequencing analysis was carried out on the PCR products. All data were grouped according to testicular location. Results Seven variations of a single nucleotide (SNVs) were identified both in patients with cryptorchidism and in controls: rs2286663 (c.27G > A), rs1047233 (c.126A > G) and rs6523 (c.178A > G) at exon 1, rs74531687 (c.191-30C > T) at the intron, rs121912556 (c.305G > A) at exon 2 and rs17750642 (c.*101C > A) and rs1003887 (c.*263G > A) at the untranslated region (UTR). The allelic variants rs74531687 and rs121912556 were found for the first time in the Greek population. The novel homozygotic combination of the three allelic variants rs1047233-rs6523-rs1003887 seemed to present a stronger correlation with more severe forms of cryptorchidism. Conclusions The combination of specific INSL3 SNVs rather than the existence of each one of them alone may offer a new insight into the involvement of allelic variants in phenotypic variability and severity.