Novel androgen-induced activity of an antimicrobial β-defensin: Regulation of Wolffian duct morphogenesis

Human β-defensins: The multi-functional natural peptide

The increasing threat of antibiotic resistance among pathogenic microorganisms and the urgent demand for new antibiotics require immediate attention. Antimicrobial peptides exhibit effectiveness against microorganisms, fungi, viruses, and protozoa. The discovery of human β-defensins represents a major milestone in biomedical research, opening new avenues for scientific investigation into the innate immune system and its resistance mechanisms against pathogenic microorganisms. Multiple defensins present a promising alternative in the context of antibiotic abuse. However, obstacles to the practical application of defensins as anti-infective therapies persist due to the unique properties of human β-defensins themselves and serious pharmacological and technical challenges. To overcome these challenges, diverse delivery vehicles have been developed and progressively improved for the conjugation or encapsulation of human β-defensins. This review briefly introduces the biology of human β-defensins, focusing on their multistage structure and diverse functions. It also discusses several heterologous systems for producing human β-defensins, various delivery systems created for these peptides, and patent applications related to their utilization, concluding with a summary of current challenges and potential solutions.

Epididymal mRNA expression profiles for the protein disulfide isomerase gene family: Modulation by development and androgens

BACKGROUND

The endoplasmic reticulum (ER) is the central hub for protein quality control, where the protein disulfide isomerases (PDIs), encoded by at least 21 genes, play a pivotal role. These multifunctional proteins contribute to disulfide bond formation, proper folding, and protein modifications, and may act as hormone-binding proteins (e.g., steroids), influencing hormone biology. The interplay between ER proteostasis, PDIs, and epididymis-a crucial site for sperm maturation-remains largely understudied.

OBJECTIVES

This study characterizes transcriptional signatures of Pdi genes in the epididymis.

MATERIAL AND METHODS

Transcriptional profiles of selected Pdi genes were assessed in adult Wistar rat tissues, and epididymis under different experimental conditions (developmental stages, surgical castration, and efferent ductules ligation [EDL]). In silico bioinformatic analyses identified expression trends of this gene family in human epididymal segments.

RESULTS

P4hb, Pdia3, Pdia5, Pdia6, Erp44, Erp29, and Casq1 transcripts were detected in both reproductive and non-reproductive tissues, while Casq2 exhibited higher abundance in vas deferens, prostate, and heart. Pdilt, highly expressed in testis, and Pdia2, highly expressed in heart, showed minimal mRNA levels in the epididymis. In the mesonephric duct, epididymal embryonic precursor, P4hb, Pdia3, Pdia5, Pdia6, and Erp29 mRNAs were found at gestational day (GD) 17.5. Except for Erp29, which remained stable, these Pdi transcript levels increased from GD17.5 to GD20.5, when epididymal morphogenesis occurs, and were maintained to varying degrees in the epididymis during postnatal development. Surgical castration downregulated P4hb, Pdia3, Pdia5, Pdia6, Pdilt and Erp29 transcripts, an effect reversed by testosterone replacement. Conversely, transcript levels remained unaffected by EDL, except P4hb, which was reduced in caput epididymis. All 21 PDI genes exhibited diverse transcriptional profiles across the human epididymis.

DISCUSSION AND CONCLUSION

The findings lay the foundations to explore Pdi genes in epididymal biology. As a considerable proportion of male infertility cases are idiopathic, targeting hormonal regulation of protein quality control in epididymis represents a route to address male infertility and advance therapeutic interventions in this domain.

Crucial Convolution: Genetic and Molecular Mechanisms of Coiling during Epididymis Formation and Development in Embryogenesis

As embryonic development proceeds, numerous organs need to coil, bend or fold in order to establish their final shape. Generally, this occurs so as to maximise the surface area for absorption or secretory functions (e.g., in the small and large intestines, kidney or epididymis); however, mechanisms of bending and shaping also occur in other structures, notably the midbrain–hindbrain boundary in some teleost fish models such as zebrafish. In this review, we will examine known genetic and molecular factors that operate to pattern complex, coiled structures, with a primary focus on the epididymis as an excellent model organ to examine coiling. We will also discuss genetic mechanisms involving coiling in the seminiferous tubules and intestine to establish the final form and function of these coiled structures in the mature organism.

Differential gene expression and hallmarks of stemness in epithelial cells of the developing rat epididymis

Epididymal development can be subdivided into three phases: undifferentiated, a period of differentiation, and expansion. The objectives of this study were (1) to assess gene expression profiles in epididymides, (2) predict signaling pathways, and (3) develop a novel 3D cell culture method to assess the regulation of epididymal development in vitro. Microarray analyses indicate that the largest changes in differential gene expression occurred between the 7- to 18-day period, in which 1452 genes were differentially expressed, while 671 differentially expressed genes were noted between days 18 and 28, and there were 560 differentially expressed genes between days 28 and 60. Multiple signaling pathways were predicted at different phases of development. Pathway associations indicated that in epididymides of 7- to 18-day old rats, there was a significant association of regulated genes implicated in stem cells, estrogens, thyroid hormones, and kidney development, while androgen- and estrogen-related pathways were enriched at other phases of development. Organoids were derived from CD49f + columnar cells from 7-day old rats, while no organoids developed from CD49f^- cells. Cells cultured in an epididymal basal cell organoid medium versus a commercial kidney differentiation medium supplemented with DHT revealed that irrespective of the culture medium, cells within differentiating organoids expressed p63, AQP9, and V-ATPase after 14 days of culture. The commercial kidney medium resulted in an increase in the number of organoids positive for p63, AQP9, and V-ATPase. Together, these data indicate that columnar cells represent an epididymal stem/progenitor cell population.

Epididymal embryonic development harbors TLR4/NFKB signaling pathway as a morphogenetic player

The Wolffian duct (WD) is an embryonic tissue that undergoes androgen-induced morphological changes to become the epididymis. Toll-like receptor 4 (TLR4)- and nuclear factor kB (NFKB)-induced effectors are expressed in the adult epididymis and represent important players in epididymal innate immune responses. TLR4/NFKB signaling pathway is evolutionarily conserved and plays a critical morphogenetic role in several species; however, its function during WD morphogenesis is unknown. We hypothesized that TLR4/NFKB pathway plays a role during WD development. Here we examined TLR4 expression and regulation of TLR4-target genes during rat WD morphogenesis between embryonic days (e) 17.5-20.5. The functionality of TLR4/NFKB signaling was examined using WD organotypic cultures treated with lipopolysaccharide (LPS) from E. coli (TLR4 agonist) and PDTC (NFKB inhibitor). TLR4 was detected at mRNA level in e17.5 (uncoiled duct) and e20.5 (coiled duct) WDs, and spatio-temporal changes in TLR4 immunoreactivity were observed between these two time points. Expression level analysis of a subset of TLR4-regulated genes showed that TLR4/NFKB pathway was activated after exposure of cultured WD to LPS (4 h), an event that was abrogated by PDTC. Long-term exposure of cultured WDs to LPS (96 h) resulted in dysregulations of morphogenetic events and LAMA1 immunodistribution changes, suggesting the extracellular matrix at the intersection between WD morphogenesis and balance of innate immune components. Our results unveil the epididymal morphogenesis as an event equipped with TLR4/NFKB signaling components that may serve developmental functions, and eventually transition to host defense function when the fetus is exposed to an infectious or noninfectious threat.

Beta-defensin126 is correlated with sperm motility in fertile and infertile men†

A crucial function of the epididymis is providing a surface glycocalyx that is important for sperm maturation and capacitation. Defensins are antimicrobial peptides expressed in the epididymis. In the macaque epididymis, defensin beta 126 (DEFB126) is important for sperm motility, however, it is not known whether this is the case in humans. The objectives were to determine: (1) if DEFB126 on human ejaculated sperm was correlated with sperm motility in fertile and infertile men, (2) that recombinant DEFB126 could induce immature sperm motility in vitro. Immunofluorescence staining indicated that the proportion of DEFB126-positive sperm was significantly higher in motile sperm. Furthermore, the proportion of DEFB126-labeled sperm was positively correlated with sperm motility and normal morphology. Additional studies indicated that the proportion of DEFB126-positive spermatozoa in fertile volunteers was significantly higher than in volunteers with varicocele, and in infertile volunteers with semen deficiencies. To determine the role of DEFB126 on sperm motility, the DEFB126 gene was cloned and used to generate recombinant DEFB126 in H9C2 cells (rat embryonic heart myoblast cells). Deletion mutations were created into two regions of the protein, which have been linked to male infertility. Immotile testicular spermatozoa were incubated with cells expressing the different forms of DEFB126. Full-length DEFB126 significantly increased motility of co-cultured spermatozoa. However, no increase in sperm motility was observed with the mutated forms of DEFB126. In conclusion, these results support the notion that DEFB126 is important in human sperm maturation and the potential use of DEFB126 for in vitro sperm maturation.

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.

An atlas of human proximal epididymis reveals cell-specific functions and distinct roles for CFTR

Spermatozoa released from the testis are unable to fertilize an egg without a coordinated process of maturation in the lumen of the epididymis. Relatively little is known about the molecular events that integrate this critical progression along the male genital ducts in man. Here, we use single cell RNA-sequencing to construct an atlas of the human proximal epididymis. We find that the CFTR, which is pivotal in normal epididymis fluid transport, is most abundant in surface epithelial cells in the efferent ducts and in rare clear cells in the caput epididymis, suggesting region-specific functional properties. We reveal transcriptional signatures for multiple cell clusters, which identify the individual roles of principal, apical, narrow, basal, clear, halo, and stromal cells in the epididymis. A marked cell type-specific distribution of function is seen along the duct with local specialization of individual cell types integrating processes of sperm maturation.

Differential gene expression profiles of human efferent ducts and proximal epididymis

BACKGROUND

Gene expression patterns along the epididymis are established by specific transcription factor networks that coordinate region-specific functions. In rodents, the epididymis can be divided in up to 19 segments. Based on gross anatomy, the human epididymis is divided into caput, corpus, and cauda segments together with efferent ducts that occupy the proximal part of this organ.

OBJECTIVES

To determine to which extent gene expression pattern is segmented along the efferent ducts and the proximal region of the epididymis in men of reproductive age.

MATERIALS AND METHODS

Epididymal transcriptome profiling was performed on eight distinct regions from three donors. Microarray analysis was performed on a gene-chip microarray. Differentially expressed genes (DEGs)>2-fold change (P < .05) were clustered in relation to their intensity profiles. Overrepresented biological functions from gene ontology were searched using DAVID 6.8. Expression profiles were validated by qRT-PCR quantification of selected genes.

RESULTS

There were no DEGs among segments 1-3 of efferent ducts region neither among segments 4-6 of the caput epididymis. 1058 DEGs were identified between efferent ducts and the epididymis, whereas 444 and 846 DEGs distinguished the caput from the corpus (section 7) and cauda (section 8) epididymis, respectively. A total of 131 DEGs were detected between corpus (7) and cauda (8) transcriptomes. Up-regulated DEGs in the efferent ducts were predominantly related to cilium assembly/movement and cell differentiation. Fertilization, defense, and immune responses were associated with caput epididymis (4-6), while spermatogenesis and protein binding were found all along the epididymis (4-8).

DISCUSSION

The proximal human epididymis is exclusively occupied by efferent ducts with a distinct DEG profile compared with the downstream epididymal segments. Moreover, gene expression profiling revealed two regions in the human epididymis: the caput and the distal corpus/cauda region.

CONCLUSIONS

Human epididymal transcriptome reveals limited DEGs, and efferent ducts have a distinct DEGs profile.

In search of new paradigms for epididymal health and disease: innate immunity, inflammatory mediators, and steroid hormones

The primary job of the epididymis is to mature and protect the luminally transiting spermatozoa. Mounting evidence is showing that innate immune components [including Toll-like receptors (TLRs) and antimicrobial proteins, among which are β-defensins] and inflammatory mediators, under the primary influence of androgens, participate in the cellular and molecular processes that define this tissue. Here, we present an overview of the contributions of these signaling pathway components during epididymal homeostasis and discuss the hypotheses as to their involvement in epididymitis, the most common urological inflammatory condition in men, frequently impairing their fertility. Drawing primarily from rodent models, we also focus on how the distribution and functional expression of innate immune components are differentially regulated in the prenatal developing epididymis, providing new insights into the disruption of these signaling pathways throughout the lifespan. Male infertility is caused by a variety of conditions, such as congenital malformations, genetic and endocrine disorders, exposure to environmental toxicants, and inflammatory/infectious conditions. More than one-third of infertile men with an idiopathic condition cannot currently be adequately diagnosed. Thinking about the innate immunity and inflammation context of the epididymis may provide new insights and directions as to how these systems contribute to male fertility, as well as also uncover urological and andrological outcomes that may aid clinicians in diagnosing and preventing epididymal pathologies.