Gene Expression Changes Underlying Idiopathic Central Hypogonadism in Cryptorchidism with Defective Mini-Puberty

Abstract

The whole genome RNA profiling of testicular biopsies by DNA strand-specific RNA sequencing was examined to determine a potential causative role of isolated congenital cryptorchidism in azoospermia and/or infertility in the context of our previously published GeneChip data. Cryptorchid patients, aged 7 months to 5 years and otherwise healthy, were enrolled in this prospective study. During surgery, testicular tissue biopsies were obtained for histological examination and RNA sequencing. Fifteen patients were selected based on the histological results and were divided into 2 groups. Seven were classified as belonging to the high infertility risk (HIR) and 8 to the low infertility risk (LIR) group. Cryptorchid boys in the HIR group lacked transformation of gonocytes into Ad spermatogonia due to impaired mini-puberty. This group of patients will be infertile despite successful surgery. The new important finding was a decreased PROK2, CHD7, FGFR1, and SPRY4 gene expression in the HIR group. Furthermore, identification of multiple differences in gene expression between HIR and LIR groups underscores the importance of an intact hypothalamic-pituitary-gonadal axis for fertility development. Our RNA profiling data strongly support the theory that in the HIR group of cryptorchid boys insufficient PROK2/CHD7/FGFR1/SPRY4 gene expression induces deficient LH secretion, resulting in impaired mini-puberty and infertility. We therefore recommend hormonal treatment for this cohort of cryptorchid boys with defective mini-puberty following a seemingly successful orchidopexy.

GnRHa Treatment of Cryptorchid Boys Affects Genes Involved in Hormonal Control of the HPG Axis and Fertility

“…These data strongly support the theory that in HIR cryptorchid boys, insufficient PROK2, CHD7, FGFR1 , and SPRY4 gene expression induces deficient LH secretion, which results in impaired mini-puberty and ultimately in adult infertility [Hadziselimovic et al, 2016]. In male infants, gonadotropin secretion increases between 2 and 4 months after birth, which stimulates Leydig cells to secrete testosterone [Forest et al, 1974;Winter et al, 1976].…”

“…The second testis of all patients was orchidopexied and biopsied 6 months after their initial surgery. In addition, RNA sequencing data from our previous study (7 HIR and 8 LIR patients) were included [Hadziselimovic et al, 2016]. Thus, altogether results from 22 patients were compared.…”

Genes Involved in Long-Term Memory Are Expressed in Testis of Cryptorchid Boys and Respond to GnRHa Treatment

“…It is, however, possible to compare normal and pathological testis to extract meaningful information about mRNA levels associated with specific cell populations [Hadziselimovic et al, 2009[Hadziselimovic et al, , 2016Chalmel et al, 2012]. In this study, samples from HIR patients before and after GnRHa treatment were analyzed and compared to the samples from untreated LIR patients (controls).…”

“…Our results are consistent with the hypothesis that hypogonadotropic hypogonadism in cryptorchid boys with altered mini-puberty may affect neuronal genes important for memory and learning, which could help explaining the negative correlation between cryptorchidism and intellectual abilities. During mini-puberty, which occurs at 30 to 90 days after birth, increased levels of luteinizing hormone (LH) and testosterone induce the transition of gonocytes into Ad (dark) spermatogonia that are stem cells for sperm development [Hadziselimovic et al, 2005[Hadziselimovic et al, , 2016. Ad spermatogonia are a key marker of potential fertility, since in the testis of cryptorchid boys who belong to the high infertility risk (HIR) group, the transition of gonocytes into Ad spermatogonia is lacking due to impaired LH and testosterone secretion [Hadziselimovic and Hoecht, 2008].…”

“…expression controlled through the master regulatory genes EGR4 and PITIX1 [Hadziselimovic et al, 2016]. Among patients who had orchidopexy during childhood, sperm counts were normal in 94% of the cases whose prepubertal testis contained Ad spermatogonia (low infertility risk, LIR), while an abnormally low sperm count was found in 92% of men who lacked Ad spermatogonia at the time of orchidopexy [Hadziselimovic and Hoecht, 2008].…”