Seminar

Male infertility

The function and regulatory mechanisms of 5-methylcytidine (m⁵C) in oligoasthenospermia remain unclear. In this study, we made a mouse model of oligoasthenospermia through the administration of busulfan (BUS). For the first time, we demonstrated that m⁵C levels decreased in oligoasthenospermia. The m⁵C levels were upregulated through the treatments of 5-methylcytidine. The testicular morphology and sperm concentrations were improved via upregulating m⁵C. The cytoskeletal regenerations of testis and sperm were accompanying with m⁵C treatments. m⁵C treatments improved T levels and reduced FSH and LH levels. The levels of ROS and MDA were significantly reduced through m⁵C treatments. RNA sequencing analysis showed m⁵C treatments increased the expression of genes involved in spermatid differentiation/development and cilium movement. Immunofluorescent staining demonstrated the regeneration of cilium and quantitative PCR (qPCR) confirmed the high expression of genes involved in spermatogenesis. Collectively, our findings suggest that the upregulation of m⁵C in oligoasthenospermia facilitates testicular morphology recovery and male infertility via multiple pathways, including cytoskeletal regeneration, hormonal levels, attenuating oxidative stress, spermatid differentiation/development and cilium movement. m⁵C may be a potential therapeutic agent for oligoasthenospermia.

SAYSVFN domain-containing protein 1 (SAYSD1) is an evolutionarily conserved membrane protein that has recently been identified as a ubiquitin-fold modifier 1 (UFM1)-conjugated ribosome-recognition protein that plays a critical role in translocation-associated quality control (TAQC). However, its expression and roles in mammals in vivo remain largely unknown. We found that SAYSD1 is predominantly expressed in round and elongating spermatids and localizes in the endoplasmic reticulum (ER) of mouse testes, but not in differentiated spermatozoa. Mice deficient in Saysd1 developed normally post-partum. Furthermore, Saysd1-deficient mice were fertile, with no apparent differences in sperm morphology or motility compared with wild-type sperm, although the cauda epididymis contained slightly less sperm. Expression of the ER stress markers spliced X-box binding protein 1s (XBP1s) and CCAAT/enhancer binding protein (C/EBP)-homologous protein (CHOP) in the testes was comparable between Saysd1-deficient and wild-type mice. These results suggested that SAYSD1 is involved in sperm production in mice but is dispensable for their development and fertility.

Infertility is defined as inability to conceive despite regular unprotected sexual intercourse for greater than 1 year. Conditions involving the male partner accounts for the infertility in approximately 50% of cases. The goals of imaging in male infertility are to detect treatable/ reversible causes, imaging for sperm retrieval from testis or epididymis for assisted reproductive techniques like in vitro fertilization or intracytoplasmic sperm injection and to provide appropriate genetic counselling for prevention of occurrence of disease in future offspring. The purpose of this article is to describe imaging features in various causes of male infertility to acquaint radiologists with various imaging appearances of causes of male infertility to avoid missing these pathologies.

Nonobstructive azoospermia (NOA) is the most serious form of spermatogenesis abnormalities in male infertility. Genetic factors are important to consider as elements leading to NOA. Although many pathogenic genes have been reported, the causative genes of NOA for many patients are still unknown. In this study, we found ten point mutations in the gene encoding homeodomain-interacting protein kinase 4 (HIPK4) in patients with NOA, and using in vitro studies, we determined a premature termination point mutation (p. Lys490∗, c.1468A>T) that can cause decreased expression of HIPK4. Our phosphoproteomic analysis of Hipk4^−/− testes revealed phosphorylation of multiple proteins regulated by HIPK4 during spermiogenesis. We also confirmed that a substrate of HIPK4 with four downregulated phosphorylation sites matching the xSPx motif is the known manchette-related protein RIMS-binding protein 3, which is required for sperm head morphogenesis. Therefore, we conclude HIPK4 regulates the phosphorylation of manchette protein RIMS-binding protein 3 and plays essential roles in sperm head shaping and male fertility.

To investigate the association between subfertility and risk of cardiovascular disease (CVD) outcomes.

Prospective study.

Population-based cohort.

We studied 31,629 women and 17,630 men participating in the Trøndelag Health Study.

Self-reported subfertility. As men were not directly asked about fertility, male partners of female participants were identified through linkage to the Medical Birth Registry of Norway and assigned the fertility information obtained from their partners.

The primary outcomes were stroke and coronary heart disease in women and men with and without a history of subfertility. The secondary outcomes were myocardial infarction and angina (subgroups of coronary heart disease) and any CVD (stroke or coronary heart disease). Information on CVD was available by linkage to hospital records. We used Cox proportional hazards models adjusted for age at participation in the Trøndelag Health Study (linear + squared), birth year, smoking history, cohabitation, and education. Cardiometabolic factors were assessed in separate models.

A total of 17% of women and 15% of men reported subfertility. In women, subfertility was modestly associated with an increased risk of stroke (age-adjusted hazard ratio [aaHR], 1.19; 95% confidence interval [CI], 1.02–1.39; adjusted hazard ratio [aHR]; 1.18; 95% CI, 1.01–1.37) and coronary heart disease (aaHR, 1.19; 95% CI, 1.06–1.33; aHR, 1.16; 95% CI, 1.03–1.30) compared with fertile women. In men, we observed a weak positive association for stroke (aaHR, 1.11; 95% CI, 0.91–1.34; aHR, 1.10; 95% CI, 0.91–1.33) and a weak inverse association for coronary heart disease (aaHR, 0.92; 95% CI, 0.81–1.05; aHR, 0.93; 95% CI, 0.81–1.06).

We observed modestly increased risks of CVD outcomes in women and some weak associations in men, although with no strong statistical evidence on sex differences. We acknowledge that we were only able to include men linked to pregnancies ending at 12 completed gestational weeks or later, potentially resulting in selection bias and misclassification of history of subfertility in analyses of male partners. Despite the large sample size, our results indicate the need for larger studies to obtain precise results in both sexes and determine whether there are true sex differences.

Riesgo de enfermedad cardiovascular en mujeres y hombres con subfertilidad: Trøndelag Health Study.

Investigar la asociación entre subfertilidad y el riesgo en los resultados de enfermedades cardiovasculares (CVD).

Estudio prospectivo.

Estudio de cohortes poblacional.

Estudiamos 31,629 mujeres y 17,630 varones que participaron en el Trøndelag Health Study.

Subfertilidad informada por ellos mismos. Puesto que a los varones no se les preguntó directamente sobre la fertilidad, se identificó a las parejas masculinas de las mujeres participantes a través del enlace con el Registro de Nacimientos de Noruega y se les asignó la información sobre fertilidad obtenida de sus parejas.

Los resultados principales fueron accidente cerebrovascular y patología coronaria en mujeres y hombres con y sin historia de subfertilidad. Los resultados secundarios fueron infarto de miocardio y angina (subgrupos de enfermedad coronaria cardiaca) y cualquier enfermedad cardiovascular (accidente cerebrovascular o enfermedad coronaria cardiaca). La información sobre CVD estaba disponible a través de enlace con los registros hospitalarios. Se utilizaron los modelos de riesgos proporcionales de Cox ajustados por edad y participación en el Trøndelag Health Study (lineal + cuadrado), año de nacimiento, historia de tabaquismo, convivencia y nivel de estudios. Los factores cardiometabólicos se evaluaron en modelos separados.

Un total de 17% de mujeres y un 15% de hombres reportaron subfertilidad. En mujeres, la subfertilildad se asoció de manera modesta con aumento de riesgo de accidente cerebrovascular (ratio de riesgo ajustado por edad [aaHR], 1.19; 95% intervalo de confianza [CI], 1.02–1.39; ratio de riesgo ajustado [aHR]; 1.18; 95% CI, 1.01–1.37) y enfermedad coronaria cardiaca (aaHR, 1.19; 95% CI, 1.06–1.33; aHR, 1.16; 95% CI, 1.03–1.30) en comparación con mujeres fértiles. En varones, se observó una débil asociación con ictus (aaHR, 1.11; 95% CI, 0.91–1.34; aHR, 1.10; 95% CI, 0.91– 1.33) y una asociación inversa débil con enfermedad coronaria cardiaca (aaHR, 0.92; 95% CI, 0.81–1.05; aHR, 0.93; 95% CI, 0.81–1.06).

Se observó un modesto incremento del riesgo de resultados de CVD en mujeres y alguna asociación débil en hombres, aunque no hubo evidencias estadísticas fuertes en las diferencias de sexo. Reconocemos que solamente fuimos capaces de incluir hombres relacionados con embarazos finalizados a las 12 semanas completas o más de gestación, lo cual puede resultar en un sesgo de selección y clasificación errónea de la historia de subfertilidad en el análisis de las parejas masculinas. A pesar del amplio tamaño muestral, nuestros resultados indican la necesidad de estudios más grandes para obtener resultados precisos en ambos sexos y determinar si existen diferencias reales entre los dos sexos.

The importance of the epididymis on sperm maturation and consequently male fertility has been well documented. The pseudostratified epithelium of the epididymis is comprised of multiple cell types, including principal cells, which are the most abundant, and basal cells. The role of basal cells has been unclear and has been a source of discussion in the literature. However, the recent demonstration that these cells are multipotent or adult stem cells has opened new areas of research in epididymal biology. One such avenue is to understand the regulation of these stem cells, and to exploit their properties to develop tools for toxicological studies to elucidate the effects of chemicals on cell differentiation and epididymal function in vitro. Studies in both rat and mouse have shown that purified single epididymal basal cells cultured under 3D conditions can proliferate and differentiate to form organoids, or mini organs. Furthermore, these epididymal basal stem cells can self-renew and differentiate into other epididymal cell types. It is known that during epididymal development, basal cells are derived from undifferentiated columnar cells, which have been reported to share common properties to stem cells. Like basal cells, these undifferentiated columnar cells can also form organoids under 3D culture conditions and can differentiate into basal, principal and clear cells. Organoids derived from either basal cells or columnar cells offer unique models for toxicology studies and represent an exciting and emerging approach to understand the epididymis.