Lipopolysaccharide-induced epididymitis disrupts epididymal beta-defensin expression and inhibits sperm motility in rats

The potential influence and intervention measures of gut microbiota on sperm: it is time to focus on testis-gut microbiota axis

As the global male infertility rate continues to rise, there is an urgent imperative to investigate the underlying causes of sustained deterioration in sperm quality. The gut microbiota emerges as a pivotal factor in host health regulation, with mounting evidence highlighting its dual influence on semen. This review underscores the interplay between the Testis-Gut microbiota axis and its consequential effects on sperm. Potential mechanisms driving the dual impact of gut microbiota on sperm encompass immune modulation, inflammatory responses mediated by endotoxins, oxidative stress, antioxidant defenses, gut microbiota-derived metabolites, epigenetic modifications, regulatory sex hormone signaling. Interventions such as probiotics, prebiotics, synbiotics, fecal microbiota transplantation, and Traditional natural herbal extracts are hypothesized to rectify dysbiosis, offering avenues to modulate gut microbiota and enhance Spermatogenesis and motility. Future investigations should delve into elucidating the mechanisms and foundational principles governing the interaction between gut microbiota and sperm within the Testis-Gut microbiota Axis. Understanding and modulating the Testis-Gut microbiota Axis may yield novel therapeutic strategies to enhance male fertility and combat the global decline in sperm quality.

Loss of DIS3L in the initial segment is dispensable for sperm maturation in the epididymis and male fertility

DIS3L, a catalytic exoribonuclease associated with the cytoplasmic exosome complex, degrades cytoplasmic RNAs and is implicated in cancers and certain other diseases in humans. Epididymis plays a pivotal role in the transport, maturation, and storage of sperm required for male fertility. However, it remains unclear whether DIS3L-mediated cytoplasmic RNA degradation plays a role in epididymis biology and functioning. Herein, we fabricated a Dis3l conditional knockout (Dis3l cKO) mouse line in which DIS3L was ablated from the principal cells of the initial segment (IS). Morphological analyses showed that spermatogenesis and IS differentiation occurred normally in Dis3l cKO mice. Additionally, the absence of DIS3L had no dramatic influence on the transcriptome of IS. Moreover, the sperm count, morphology, motility, and acrosome reaction frequency in Dis3l cKO mice were comparable to that of the control, indicating that the Dis3l cKO males had normal fertility. Collectively, our genetic model demonstrates that DIS3L inactivation in the IS is nonessential for sperm maturation and male fertility.

The Sperm-Associated Antigen 11A (Spag11a) Knockout Mice Display Sub-Fertility and Perturbations in the Sperm Proteome

Spermatogenesis and sperm maturation that occur in the testis and epididymis respectively are crucial for fertility. Factors secreted by the testicular and epididymal epithelial cells govern the processes of gametogenesis and maturation. Proteins encoded by the sperm-associated antigen 11a (Spag11a) gene are implicated as having a possible role in sperm maturation. However, studies that demonstrate their definite role in fertility and sperm function using knockout models have not yet reported. In this study, Spag11a knockout mice were generated, genotyped and the reproductive parameters (fecundity, sperm count, capacitation, and acrosome reaction) and sperm proteome were determined. Litter size and sperm count were decreased in the Spag11a knockout mice when compared to the wild-type controls. Spermatozoa from the knockout mice were able to undergo capacitation. However, acrosome reaction did not occur in sperm obtained from knockout mice. Structural abnormalities in the head and tail structures were evident in the spermatozoa of knockout mice. Perturbations in the expression of sperm proteins that are involved in gametogenesis were evident. The subfertility observed in Spag11a knockout mice could be a manifestation of lower sperm count, impaired acrosome reactions, and disturbances in the sperm proteome. The results of this study lend further support to the role of Spag11a gene in male gamete function.

Immunodeviation towards T cell-mediated immune response in the testes of LPS-induced mouse epididymo-orchitis

The testicular consequences of acute epididymo-orchitis remain largely unelucidated in long-term damage, which might be a neglected factor for male infertility. In this study, the differential phenotype of testicular immune cell subpopulations in lipopolysaccharide (LPS)-induced mouse epididymo-orchitis were analyzed by flow cytometry on day 1, day 7, and day 28. The number of macrophages, neutrophils, and myeloid-derived suppressor cells (MDSCs) steadily decreased in the testes with inoculation. Total F4/80-CD11c+ dendritic cells (DCs) maintained a relatively stable level, whereas conventional type 1 dendritic cells (cDC1) increased gradually from day 1 to day 28. There was a lower number of CD4+ and CD8+ T cells at day 1 and day 7, and they had similar results with a ceiling level at day 28. The testes displayed a higher level of CD3+ T cells but a lower frequency of macrophages, cDC2, and neutrophils at 28 days post-inoculation compared with the epididymis. In summary, our data indicates acute epididymo-orchitis could lead to long-term damage in the testes, which is characterized by CD3+ T cell (including CD4+ and CD8+ T cells)-mediated immune responses.

The gut microbiota contributes to methamphetamine-induced reproductive toxicity in male mice

Methamphetamine (METH) is a psychostimulant drug belonging to the amphetamine-type stimulant class, known to exert male reproductive toxicity. Recent studies suggest that METH can disrupt the gut microbiota. Furthermore, the gut-testis axis concept has gained attention due to the potential link between gut microbiome dysfunction and reproductive health. Nonetheless, the role of the gut microbiota in mediating the impact of METH on male reproductive toxicity remains unclear. In this study, we employed a mouse model exposed to escalating doses of METH to assess sperm quality, testicular pathology, and reproductive hormone levels. The fecal microbiota transplantation method was employed to investigate the effect of gut microbiota on male reproductive toxicity. Transcriptomic, metabolomic, and microbiological analyses were conducted to explore the damage mechanism to the male reproductive system caused by METH. We found that METH exposure led to hormonal disorders, decreased sperm quality, and changes in the gut microbiota and testicular metabolome in mice. Testicular RNA sequencing revealed enrichment of several Gene Ontology terms associated with reproductive processes, as well as PI3K-Akt signaling pathways. FMT conveyed similar reproductive damage from METH-treated mice to healthy recipient mice. The aforementioned findings suggest that the gut microbiota plays a substantial role in facilitating the reproductive toxicity caused by METH, thereby highlighting a prospective avenue for therapeutic intervention in the context of METH-induced infertility.

Histological study of Bactrian camel cryptorchidism and expression of immunoglobulin λ light chain in the testicular and epididymis of cryptorchid Bactrian camel

Lambda light chains (λ-LCs) are frequently responsible for triggering the activation of inflammatory factors in autoimmune disorders, and an increase in their levels will cause various pathological changes in serum. The aim of this study was to determine the histological differences between the epididymis and testis of normal and cryptorchid Bactrian camels and the differences in λ-LC expression in the epididymis and testis of normal and cryptorchid Bactrian camels. Haematoxylin and eosin (H&E) staining was used to examine the pathological changes in cryptorchidism. The gene and protein levels of λ-LC were determined using RT-qPCR and western blot. The distribution of λ-LCs was assessed by immunohistochemistry and immunofluorescence. Compared with that in normal Bactrian camels, the diameter of the epididymal lumen and the thickness of the epithelium were decreased in the epididymis of cryptorchidic animals. Additionally, no sperm was detected in the cavity of the cryptorchidic epididymis. Meanwhile, the expression of λ-LC was significantly increased in the cryptorchidic epididymis at both the mRNA and protein levels (p < .05). The highest protein expression of λ-LC was found in epididymal epithelial halo cells and testicular Sertoli cells. These findings suggested that the structural changes observed in the epididymal epithelium of cryptorchidic camels affect its secretory and absorptive functions. Additionally, the high level of λ-LC expression recorded in halo cells suggested that these cells play an important role in epithelial immunity in cryptorchidic Bactrian camels. Furthermore, the high λ-LC expression levels detected in normal testicular Sertoli cells indicated that λ-LCs may be involved in spermatogenesis. The results of this study provide clues for an in-depth study of immunological sterility in cryptorchidic Bactrian camels.

A Narrative Review Discussing Vasectomy-Related Impact upon the Status of Oxidative Stress and Inflammation Biomarkers and Semen Microbiota

Background: Male contraceptive approaches besides tubal sterilization involve vasectomy and represent the method of choice among midlife men in developing countries thanks to many advantages. However, the subsidiary consequences of this intervention are insufficiently explored since the involved mechanisms may offer insight into a much more complex picture. Methods: Thus, in this manuscript, we aimed to reunite all available data by searching three separate academic database(s) (PubMed, Web of Knowledge, and Scopus) published in the past two decades by covering the interval 2000–2023 and using a predefined set of keywords and strings involving “oxidative stress” (OS), “inflammation”, and “semen microbiota” in combination with “humans”, “rats”, and “mice”. Results: By following all evidence that fits in the pre-, post-, and vasectomy reversal (VR) stages, we identified a total of n = 210 studies from which only n = 21 were finally included following two procedures of eligibility evaluation. Conclusions: The topic surrounding this intricate landscape has created debate since the current evidence is contradictory, limited, or does not exist. Starting from this consideration, we argue that further research is mandatory to decipher how a vasectomy might disturb homeostasis.

Beta-defensins as marker for male fertility: a comprehensive review†

Bovine male fertility in animals has a direct impact on the productivity of dairy herds. The epididymal sperm maturations involve extensive sperm surface modifications to gain the fertilizing ability, especially by absorptions of the plethora of biomolecules, including glycoprotein beta-defensins (BDs), enzymes, organic ions, protein, and phospholipids. Defensins are broad-range nonspecific antimicrobial peptides that exhibit strong relations with innate and adaptive immunity, but their roles in male fertility are relatively recently identified. In the course of evolution, BD genes give rise to different clusters with specific functions, especially reproductive functions, by undergoing duplications and nonsynonymous mutations. BD polymorphisms have been reported with milk compositions, disease resistance, and antimicrobial activities. However, in recent decades, the link of BD polymorphisms with fertility has emerged as an appealing improvement of reproductive performance such as sperm motility, membrane integrity, cervical mucus penetration, evading of uterus immunosurveillance, oviduct cell attachment, and egg recognition. The reproductive-specific glycosylated BD class-A BDs (CA-BDs) have shown age- and sex-specific expressions in male reproductive organs, signifying their physiological pleiotropism, especially in the sperm maturation and sperm transport in the female reproductive tract. By considering adult male reproductive organ-specific BD expressions, importance in sperm functionalities, and bioinformatic analysis, we have selected two bovine BBD126 and BBD129 genes as novel potential biomarkers of bovine male fertility. Despite the importance of BDs, however, genomic characterization of most BD genes across most livestock and nonmodel organisms remains predictive/incomplete. The current review discusses our understanding of BD pleiotropic functions, polymorphism, and genomic structural attributes concerning the fertilizability of the male gamete in dairy animals.

Chronic alcohol-induced dysbiosis of the gut microbiota and gut metabolites impairs sperm quality in mice

Studies have indicated that the ethanol exposure impairs the gut microbiota, At the same time, high levels of alcohol exposure damage sperm in mice. However, whether the gut microbiota is involved in mediating the effects of alcohol on sperm quality remains unclear. This study aimed to assess the effect of chronic alcohol consumption on intestinal microbiota in mice and analyze the potential pathophysiological effect of altered intestinal microbiota on sperm quality. We established a mouse model of chronic alcohol consumption by allowing male C57 mice to freely ingest 10% ethanol for 10 weeks, and collected the fecal microbiota of the male mice in the chronic drinking group (alcohol) and the control group (control) and transplanted the specimens into the transplant groups (the alcohol-fecal microbiota transplantation [FMT] group and the control-FMT group). Sperm quality was significantly decreased in the alcohol-FMT group compared with the control-FMT group. Gut microbiota analysis revealed that the abundance of 11 operational taxonomic units (OTUs) was altered in the alcohol-FMT group. Nontargeted metabolomics identified 105 differentially altered metabolites, which were mainly annotated to amino acids, lipids, glycerophosphoethanolamine, organic oxygenic compounds, organic acids and their derivatives, steroids, and flavonoids. In particular, the oxidative phosphorylation pathway, which is the key to spermatogenesis, was significantly enriched in the alcohol-FMT group. Moreover, compared with the control-FMT group, the alcohol-FMT group presented significantly higher serum endotoxin and inflammatory cytokine levels, with more pronounced T cell and macrophage infiltration in the intestinal lamina propria and elevated levels of testicular inflammatory cytokines. In addition, RNA sequencing showed significant differences in the expression of testis-related genes between the alcohol-FMT group and the control-FMT group. In particular, the expression of genes involved in gamete meiosis, testicular mitochondrial function, and the cell division cycle was significantly reduced in alcohol-FMT mice. In conclusion, these findings indicated that intestinal dysbiosis induced by chronic alcohol consumption may be an important factor contributing to impaired sperm quality. Chronic alcohol consumption induces intestinal dysbiosis, which then leads to metabolic disorders, elevated serum endotoxin and inflammatory cytokine levels, testicular inflammation, abnormal expression of related genes, and ultimately, impaired sperm quality. These findings are potentially useful for the treatment of male infertility.

Defensins: defenders of human reproductive health

BACKGROUND

Reproductive tract infection is an important factor leading to male and female infertility. Among female infertility factors, microbial and viral infections are the main factors affecting female reproductive health and causing tubal infertility, ectopic tubal pregnancy and premature delivery. Among male infertility factors, 13-15% of male infertility is related to infection. Defensins are cationic antibacterial and antiviral peptides, classified into α-defensins, β-defensins and θ-defensins. Humans only have α-defensins and β-defensins. Apart from their direct antimicrobial functions, defensins have an immunomodulatory function and are involved in many physiological processes. Studies have shown that defensins are widely distributed in the female reproductive tract (FRT) and male reproductive tract (MRT), playing a dual role of host defence and fertility protection. However, to our knowledge, the distribution, regulation and function of defensins in the reproductive tract and their relation to reproduction have not been reviewed.

OBJECTIVE AND RATIONALE

This review summarizes the expression, distribution and regulation of defensins in the reproductive tracts to reveal the updated research on the dual role of defensins in host defence and the protection of fertility.

SEARCH METHODS

A systematic search was conducted in PubMed using the related keywords through April 2022. Related data from original researches and reviews were integrated to comprehensively review the current findings and understanding of defensins in the human reproductive system. Meanwhile, female and male transcriptome data in the GEO database were screened to analyze defensins in the human reproductive tracts.

OUTCOMES

Two transcriptome databases from the GEO database (GSE7307 and GSE150852) combined with existing researches reveal the expression levels and role of the defensins in the reproductive tracts. In the FRT, a high expression level of α-defensin is found, and the expression levels of defensins in the vulva and vagina are higher than those in other organs. The expression of defensins in the endometrium varies with menstrual cycle stages and with microbial invasion. Defensins also participate in the local immune response to regulate the risk of spontaneous preterm birth. In the MRT, a high expression level of β-defensins is also found. It is mainly highly expressed in the epididymal caput and corpus, indicating that defensins play an important role in sperm maturation. The expression of defensins in the MRT varies with androgen levels, age and the status of microbial invasion. They protect the male reproductive system from bacterial infections by neutralizing lipopolysaccharide and downregulating pro-inflammatory cytokines. In addition, animal and clinical studies have shown that defensins play an important role in sperm maturation, motility and fertilization.

WIDER IMPLICATIONS

As a broad-spectrum antimicrobial peptide without drug resistance, defensin has great potential for developing new natural antimicrobial treatments for reproductive tract infections. However, increasing evidence has shown that defensins can not only inhibit microbial invasion but can also promote the invasion and adhesion of some microorganisms in certain biological environments, such as human immunodeficiency virus. Therefore, the safety of defensins as reproductive tract anti-infective drugs needs more in-depth research. In addition, the modulatory role of defensins in fertility requires more in-depth research since the current conclusions are based on small-size samples. At present, scientists have made many attempts at the clinical transformation of defensins. However, defensins have problems such as poor stability, low bioavailability and difficulties in their synthesis. Therefore, the production of safe, effective and low-cost drugs remains a challenge.

S100A4 promotes the progression of lipopolysaccharide-induced acute epididymitis in mice†

S100A4 has been suggested to be a critical regulator of tumor metastasis and is implicated in the progression of inflammation. The aim of this study is to investigate the expression and possible role of S100A4 in epididymitis. Using a mouse model of epididymitis induced by the injection of lipopolysaccharide (LPS) in the deferent duct, we found that LPS administration induced an upregulation of S100a4 transcription (P < 0.05) and a recruitment of S100A4 positive cells in the epididymal interstitium of wild type (WT) mice. Co-immunofluorescence showed that S100A4 was mainly expressed by granulocytes, CD4 lymphocytes, and macrophages. Deficiency of S100A4 reduced epididymal pathological reaction and the mRNA levels of the pro-inflammatory cytokines IL-1β and TNF-α (P < 0.01), suggesting that S100A4 promotes the progression of epididymitis. Furthermore, S100A4 deficiency alleviated the decline of sperm motility and rectified the abnormal expression of sperm membrane protein AMAD3, which suggested that in the progression of epididymitis, S100A4 aggravates the damage to sperm vitality. In addition, both Ki-67 marked cell proliferation and transferase-mediated dUTP-biotin nick end labeling detected cell apoptosis were reduced in S100a4-/- mice compared with WT mice after LPS treatment, indicating that S100A4 promotes both cell proliferation and cell apoptosis in epididymitis. Overall, these results demonstrate that S100A4 promotes the progression of LPS-induced epididymitis and facilitates a decline in sperm vitality, and its function may be related to the process of cell proliferation and apoptosis during inflammation.

C-Type Natriuretic Peptide Plays an Anti-Inflammatory Role in Rat Epididymitis Induced by UPEC

Human epididymitis is mainly caused by retrograde urinary tract infection with uropathogenic Escherichia coli (UPEC). This disease is an important factor (accounting for 20-30%) causing male infertility. C-type natriuretic peptide (CNP), a protein composed of 22 amino acids, is proved to play an immunoregulatory role in respiratory and cardiovascular systems. CNP is expressed extremely high in the epididymis, but whether CNP plays the same role in acute epididymitis is unclear. At first, we established an acute caput epididymitis model in rats with UPEC and treated them with CNP to measure inflammatory damage. Then RNA-seq transcriptome technology was used to reveal potential signal pathways. Secondly, the turbidity and activity of UPEC were assessed using a microplate reader and the amount of UPEC by agar plates after incubation with CNP. Thirdly, macrophages in caput epididymis were tested by immunohistochemistry (IHC). Meanwhile, lipopolysaccharide (LPS) with or without CNP was used to stimulate the macrophage (RAW264.7) in vitro and to detect the expression level of pro-inflammatory factors. Finally, the macrophage (RAW264.7) was treated with CNP, 8-Br-cGMP [cyclic guanosinc monophosphate (cGMP) analog] and KT5823 [protein kinase G (PKG) inhibitor], and the expression level of nuclear factor-k-gene binding (NF-kB) signal pathway was examined. The results showed that the damage of epididymis induced by UPEC as well as the pro-inflammatory factors could be alleviated significantly with CNP treatment. CNP could inhibit the activity and numbers of bacteria in both in vivo and in vitro experiments. Moreover, CNP repressed the invasion, and the expression of pro-inflammatory factors (such as NF-kB, IL-1β, IL-6, TNF-α) in macrophages and its effect could be inhibited by KT5823. Therefore, we drew a conclusion from the above experiments that CNP alleviates the acute epididymitis injury induced by UPEC. On one hand, CNP could inhibit the growth of UPEC. On the other hand, CNP could decrease invasion and inflammatory reaction of macrophages; the mechanism was involved in inhibiting NF-kB signal pathway through the cGMP/PKG in macrophages. This research would open up the possibility of using CNP as a potential treatment for epididymitis.

Deficiency for Lcn8 causes epididymal sperm maturation defects in mice

Lipocalin family members, LCN8 and LCN9, are specifically expressed in the initial segment of mouse caput epididymis. However, the biological functions of the molecules in vivo are yet to be clarified. In this study, CRISPR/Cas9 technology was used to generate Lcn8 and Lcn9 knockout mice, respectively. Lcn8-/- and Lcn9-/- male mice showed normal spermatogenesis and fertility. In the cauda epididymis of Lcn8-/- male mice, morphologically abnormal sperm was increased significantly, the proportion of progressive motility sperm was decreased, the proportion of immobilized sperm was elevated, and the sperm spontaneous acrosome reaction (AR) frequency was increased. Conversely, the knockout of Lcn9 did not have any effect on the ratio of morphologically abnormal sperm, sperm motility, and sperm spontaneous AR frequencies. These results demonstrated the role of LCN8 in maintaining the sperm quality in the epididymis, and suggested that the deficiency of LCN8 leads to epididymal sperm maturation defects.

The truncated human beta-defensin 118 can modulate lipopolysaccharide mediated inflammatory response in RAW264.7 macrophages

The family of human β-defensins consists of small cysteine-rich peptides, which are receiving significant attention due to their antimicrobial activity. The N-terminal cysteine motif of β-defensin is considered to contribute to its biological activity. Human β-defensin 118 (DEFB 118) is a particular anion β-defensin expressed predominantly in the male reproductive tract, but its physiological activity has not yet been revealed. In order to verify the potential role of the N-terminal domain of DEFB118 peptide in the regulation of infection, the truncated β-defensin core region of DEFB118 peptide was expressed with IMPACT-pTWIN1 system in Escherichia coli. Herein, the purified homogeneous DEFB118 peptide was identified by mass spectrometry and circular dichroism spectroscopy. The in vitro experiments revealed that DEFB118 peptide exhibited prominent LPS-binding potency (K_D: 2.94 nM). Moreover, the DEFB118 core peptide significantly inhibited the mRNA level of LPS-induced inflammatory cytokines including IL-α, IL-1β, IL-6 and TNF-α in RAW264.7 cells, and correspondingly decreased secretion of IL-6 and TNF-α. We concluded that strong binding of DEFB118 to LPS might prevent LPS from binding to its receptor, and hence inhibited cytokines secretion. The results of this study may be a benefit to elucidate the immune protection of DEFB118 in the male reproductive tract.

Differential Immune Response to Infection and Acute Inflammation Along the Epididymis

The epididymis is a tubular structure connecting the vas deferens to the testis. This organ consists of three main regions—caput, corpus, and cauda—that face opposing immunological tasks. A means of combating invading pathogens is required in the distally located cauda, where there is a risk of ascending bacterial infections originating from the urethra. Meanwhile, immune tolerance is necessary at the caput, where spermatozoa with immunogenic neo-antigens originate from the testis. Consistently, when challenged with live bacteria or inflammatory stimuli, the cauda elicits a much stronger immune response and inflammatory-inflicted damage than the caput. At the cellular level, a role for diverse and strategically positioned mononuclear phagocytes is emerging. At the mechanistic level, differential expression of immunoprotective and immunomodulatory mediators has been detected between the three main regions of the epididymis. In this review, we summarize the current state of knowledge about region-specific immunological characteristics and unveil possible underlying mechanisms on cellular and molecular levels. Improved understanding of the different immunological microenvironments is the basis for an improved therapy and counseling of patients with epididymal infections.

Lipopolysaccharide-induced epididymitis modifies the transcriptional profile of Wfdc genes in mice†

Whey-acidic protein four-disulfide core domain (WFDC) genes display putative roles in innate immunity and fertility. In mice, a locus on chromosome 2 contains 5 and 11 Wfdc genes in its centromeric and telomeric subloci, respectively. Although Wfdc genes are highly expressed in the epididymis, their contributions to epididymal function remain elusive. Here, we investigated whether Wfdc genes are regulated in response to lipopolysaccharide (LPS)-induced epididymitis, an inflammatory condition that impairs male fertility. We induced epididymitis in mice via (i) interstitial LPS injection into epididymal initial segment and (ii) intravasal LPS injection into the vas deferens towards cauda epididymis. Interstitial and intravasal LPS induced a differential upregulation of inflammatory mediators (interleukin 1 beta, interleukin 6, tumor necrosis factor, interferon gamma, and interleukin 10) in the initial segment and cauda epididymis within 72 h post-treatment. These changes were accompanied by a time-dependent endotoxin clearance from the epididymis. In the initial segment, interstitial LPS upregulated all centromeric (Slpi, Wfdc5, Wfdc12, Wfdc15a, and Wfdc15b) and five telomeric (Wfdc2, Wfdc3, Wfdc6b, Wfdc10, and Wfdc13) Wfdc transcripts at 24 and 72 h. In the cauda epididymis, intravasal LPS upregulated Wfdc5 and Wfdc2 transcripts at 24 h, followed by a downregulation of Wfdc15b and three telomeric (Wfdc6a, Wfdc11, and Wfdc16) gene transcripts at 72 h. Pharmacological inhibition of nuclear factor kappa B activation prevented LPS-induced upregulation of centromeric and telomeric Wfdc genes depending on the epididymal region. We show that LPS-induced inflammation differentially regulated the Wfdc locus in the proximal and distal epididymis, indicating region-specific roles for the Wfdc family in innate immune responses during epididymitis.

Wolbachia-induced expression of kenny gene in testes affects male fertility in Drosophila melanogaster

Wolbachia are Gram-negative endosymbionts that are known to cause embryonic lethality when infected male insects mate with uninfected females or with females carrying a different strain of Wolbachia, a situation characterized as cytoplasmic incompatibility (CI). However, the mechanism of CI is not yet fully understood, although recent studies on Drosophila melanogaster have achieved great progress. Here, we found that Wolbachia infection caused changes in the expressions of several immunity-related genes, including significant upregulation of kenny (key), in the testes of D. melanogaster. Overexpression of key in fly testes led to a significant decrease in egg hatch rates when these flies mate with wild-type females. Wolbachia-infected females could rescue this embryonic lethality. Furthermore, in key overexpressing testes terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling signal was significantly stronger than in the control testes, and the level of reactive oxygen species was significantly increased. Overexpression of key also resulted in alterations of some other immunity-related gene expressions, including the downregulation of Zn72D. Knockdown of Zn72D in fly testes also led to a significant decrease in egg hatch rates. These results suggest that Wolbachia might induce the defect in male host fertility by immunity-related pathways and thus cause an oxidative damage and cell death in male testes.

The Immune Characteristics of the Epididymis and the Immune Pathway of the Epididymitis Caused by Different Pathogens

The epididymis is an important male accessory sex organ where sperm motility and fertilization ability develop. When spermatozoa carrying foreign antigens enter the epididymis, the epididymis shows "immune privilege" to tolerate them. It is well-known that a tolerogenic environment exists in the caput epididymis, while pro-inflammatory circumstances prefer the cauda epididymis. This meticulously regulated immune environment not only protects spermatozoa from autoimmunity but also defends spermatozoa against pathogenic damage. Epididymitis is one of the common causes of male infertility. Up to 40% of patients suffer from permanent oligospermia or azoospermia. This is related to the immune characteristics of the epididymis itself. Moreover, epididymitis induced by different pathogenic microbial infections has different characteristics. This article elaborates on the distribution and immune response characteristics of epididymis immune cells, the role of epididymis epithelial cells (EECs), and the epididymis defense against different pathogenic infections (such as uropathogenic Escherichia coli, Chlamydia trachomatis, and viruses to provide therapeutic approaches for epididymitis and its subsequent fertility problems.

Leptin is upregulated in epididymitis and promotes apoptosis and IL-1β production in epididymal epithelial cells by activating the NLRP3 inflammasome

Epididymitis, one of the most common urological disease, is a significant cause of male infertility. Leptin is capable of modulating both reproduction and immune response. We analyzed the serum and seminal plasma levels of leptin in infertile patients with or without chronic epididymitis. Experimental epididymitis models were generated by administrating 200 μg Lipopolysaccharide (LPS) to Sprague-Dawley rats. The expression of leptin in epididymis were detected using qPCR, Western blots 6-72 h after injection, and using immunohistochemistry 72 h after injection. Besides, rat epididymal epithelial cells were isolated as an in vitro model and were treated with leptin (5-40 ng/ml, 6-48 h), LPS (1ug/ml, 6 h), and NLRP3 inflammasome inhibitor MCC950 (10 μM, 2 h). Cell Counting Kits-8 assay and Annexin V/PE assay were used to evaluate cell viability and apoptosis. Quantitive PCR and ELISA assay were used to detected inflammatory cytokines interleukin-1beta (IL-1β) production. Western Blots were used to detect molecular related to cell apoptosis, IL-1β maturation, and NLRP3 inflammasome. We found that patients with chronic epididymitis presented a significantly higher level of seminal plasma leptin and correlated declined sperm progressive motility. Leptin and leptin receptor expression in epididymis was significantly upregulated 24 h after LPS administration both in mRNA and protein level, and highly expressed in the epididymis epithelium 72 h after LPS administration. In epididymal epithelial cells, leptin reduced cell viability and promoted apoptosis in a concentration-dependent manner via cleavage of caspase-9, caspase-3, and PARP. Leptin enhanced the LPS-induced production of IL-1β, which was associated with increased IL-1β maturation and caspase-1 activation. Furthermore, NLRP3 inhibitor MCC950 attenuated the effects of leptin or co-treatment with LPS on NLRP3, ASC expression, IL-1β maturation, and caspase-1 activation, which indicated that leptin promotes IL-1β production via activating the NLRP3 inflammasome. These data suggested that leptin may act as a potential evaluation and treatment target for epididymitis and male subfertility.

Impairment of spermatogenesis and sperm motility by the high-fat diet-induced dysbiosis of gut microbes

OBJECTIVE

High-fat diet (HFD)-induced metabolic disorders can lead to impaired sperm production. We aim to investigate if HFD-induced gut microbiota dysbiosis can functionally influence spermatogenesis and sperm motility.

DESIGN

Faecal microbes derived from the HFD-fed or normal diet (ND)-fed male mice were transplanted to the mice maintained on ND. The gut microbes, sperm count and motility were analysed. Human faecal/semen/blood samples were collected to assess microbiota, sperm quality and endotoxin.

RESULTS

Transplantation of the HFD gut microbes into the ND-maintained (HFD-FMT) mice resulted in a significant decrease in spermatogenesis and sperm motility, whereas similar transplantation with the microbes from the ND-fed mice failed to do so. Analysis of the microbiota showed a profound increase in genus Bacteroides and Prevotella, both of which likely contributed to the metabolic endotoxaemia in the HFD-FMT mice. Interestingly, the gut microbes from clinical subjects revealed a strong negative correlation between the abundance of Bacteroides-Prevotella and sperm motility, and a positive correlation between blood endotoxin and Bacteroides abundance. Transplantation with HFD microbes also led to intestinal infiltration of T cells and macrophages as well as a significant increase of pro-inflammatory cytokines in the epididymis, suggesting that epididymal inflammation have likely contributed to the impairment of sperm motility. RNA-sequencing revealed significant reduction in the expression of those genes involved in gamete meiosis and testicular mitochondrial functions in the HFD-FMT mice.

CONCLUSION

We revealed an intimate linkage between HFD-induced microbiota dysbiosis and defect in spermatogenesis with elevated endotoxin, dysregulation of testicular gene expression and localised epididymal inflammation as the potential causes.

TRIAL REGISTRATION NUMBER

NCT03634644.

Comprehensive transcriptome analysis based on RNA sequencing identifies critical genes for lipopolysaccharide-induced epididymitis in a rat model

Epididymitis is a commonly diagnosed disease associated with male infertility. However, little is known about the molecules that are involved in its development. This study was to identify critical genes associated with lipopolysaccharide-induced epididymitis and analyze the molecular mechanism of epididymitis through RNA sequencing. Experimental epididymitis models were generated by administering male Sprague–Dawley rats' lipopolysaccharide. A total of 1378 differentially expressed genes, including 531 upregulated and 847 downregulated genes, were identified in the epididymitis model rats compared with those in sham-operated rats by RNA sequencing. Functional enrichment analyses suggested that the upregulated genes were markedly enriched in inflammation-related biological processes, as well as in the tumor necrosis factor (TNF) signaling pathway, cytokine–cytokine receptor interactions, complement and coagulation cascades, and in the chemokine signaling pathway. Four downregulated genes (collagen type XXVIII alpha 1 chain [Col28α1], cyclin-dependent kinase-like 1 [Cdkl1], phosphoserine phosphatase [Psph], and fatty acid desaturase 2 [Fads2]) and ten upregulated genes (CCAAT/enhancer-binding protein beta [Cebpβ], C-X-C motif chemokine receptor 2 [Cxcr2], interleukin 11 [Il11], C-C motif chemokine ligand 20 [Ccl20], nuclear factor-kappa-B inhibitor alpha [Nfkbiα], claudin 4 [Cldn4], matrix metallopeptidase 9 [Mmp9], heat shock 70 kDa protein 8 [Hspa8], intercellular cell adhesion molecule-1 [Icam1], and Jun) were successfully confirmed by real-time polymerase chain reaction. Western blot demonstrated that CDKL1 was decreased, while MMP9 and NFKBIA were increased in the experimental model group compared with those in the sham-operated group. Our study sheds new light on the understanding of the early response of the epididymis during bacterial epididymitis.

Differential tissue-specific damage caused by bacterial epididymo-orchitis in the mouse

Ascending bacterial urinary tract infections can cause epididymo-orchitis. In the cauda epididymidis, this frequently leads to persistent tissue damage. Less coherent data is available concerning the functional consequences of epididymo-orchitis on testis and caput epididymidis. This in vivo study addresses the functional and spatial differences in responsiveness of murine epididymis and testis to infection with uropathogenic Escherichia coli (UPEC). Whole transcriptome analysis (WTA) was performed on testis, caput, corpus and cauda epididymidis of adult C57BL/6 J wildtype mice. Following UPEC-induced epididymo-orchitis in these mice, epididymal and testicular tissue damage was evaluated histologically and semi-quantitatively at 10 days and 31 days post-inoculation. Expression of inflammatory markers and candidate antimicrobial genes were analysed by RT-qPCR. WTA revealed distinct differences in gene signatures between caput and cauda epididymidis, particularly amonst immunity-related genes. Cellular and molecular signs of testicular inflammation and disruption of spermatogenesis were noticed at day 10, but recovery was observed by day 31. In contrast to the cauda, the caput epididymidis did not reveal any signs of gross morphological damage or presence of pro-inflammatory processes despite confirmed infection. In contrast to beta-defensins, known UPEC-associated antimicrobial peptides (AMP), like Lcn2, Camp and Lypd8, were inherently highly expressed or upregulated in the caput following infection, potentially allowing an early luminal protection from UPEC. At the time points investigated, the caput epididymidis was protected from any obvious infection/inflammation-derived tissue damage. Studies addressing earlier time-points will conclude whether in the caput epididymidis a pro-inflammatory response is indeed not essential for effective protection from UPEC.

Immunomodulatory significance of natural peptides in mammalians: Promising agents for medical application

Modulation of immune responses by immunoregulatory agents, such as the natural or synthetic immunomodulatory peptides, has been suggested as a potential strategy to modulate immune system against infection and other immune-related diseases. These compositionally simple peptides have attracted much attention for many drug developers, due to their high activity, low toxicity and clear target specificity. Host defence peptides and milk-derived peptides are two kinds of natural immunomodulatory peptides which have been widely studied in mammalians. They could participate at the interface of innate and adaptive immunity by regulating immune effector cells. This review summarizes the recent advances in host defence peptides and milk-derived peptides as well as their general characteristics, immunomodulatory functions and possible applications.

Status of beta defensin-1 in Indian goat breeds

The present study was carried out to know the status of Beta Defensin-1 in goat semen before and after cryopreservation with beta defensin-1 supplemented semen diluent and in blood of different breeds of goat (Barbari, Jamunapari and Jakhrana). Goat semen (N-10) from each breed was collected by artificial vagina method. Immediately after collection, the volume, colour, consistency, and mass motility of ejaculate were assessed and were extended with Tris-Egg yolk-Fructose diluent having 10% (v/v) egg yolk and glycerol 6% (v/v). Samples were divided for estimation of beta defensin–1 and rest parts were cryopreserved with semen diluent having beta defensin-1 @ 10 ng/mL. Blood samples (N-30) were also collected from the same animal after semen collection. The samples were stored at –20°C until assayed. Plasma membrane of sperm was broken by freeze thaw followed by ultracentrifugation (20,000 × g for 5 min) at room temperature before ELISA test. The samples were diluted with Phosphate buffer (1:2) before analysis. The samples were analyzed using goat specific beta defensin–1 commercial kit (EO6D0419) as per the manufacturer’s instruction. The result showed that with supplementation of beta defensin-1 in goat semen, diluent maintains the concentration of beta defensin-1 even after cryopreservation. There was significant decrease (P<0.05) in beta defensin-1 concentration in sample which had no supplement in semen diluent after cryopreservation. The supplementation of beta defensin-1 in goat semen diluent improved the post-thaw immune modulatory properties of semen.

Genetic resistance to DEHP-induced transgenerational endocrine disruption

Di(2-ethylhexyl)phthalate (DEHP) interferes with sex hormones signaling pathways (SHP). C57BL/6J mice prenatally exposed to 300 mg/kg/day DEHP develop a testicular dysgenesis syndrome (TDS) at adulthood, but similarly-exposed FVB/N mice are not affected. Here we aim to understand the reasons behind this drastic difference that should depend on the genome of the strain. In both backgrounds, pregnant female mice received per os either DEHP or corn oil vehicle and the male filiations were examined. Computer-assisted sperm analysis showed a DEHP-induced decreased sperm count and velocities in C57BL/6J. Sperm RNA sequencing experiments resulted in the identification of the 62 most differentially expressed RNAs. These RNAs, mainly regulated by hormones, produced strain-specific transcriptional responses to prenatal exposure to DEHP; a pool of RNAs was increased in FVB, another pool of RNAs was decreased in C57BL/6J. In FVB/N, analysis of non-synonymous single nucleotide polymorphisms (SNP) impacting SHP identified rs387782768 and rs29315913 respectively associated with absence of the Forkhead Box A3 (Foxa3) RNA and increased expression of estrogen receptor 1 variant 4 (NM_001302533) RNA. Analysis of the role of SNPs modifying SHP binding sites in function of strain-specific responses to DEHP revealed a DEHP-resistance allele in FVB/N containing an additional FOXA1-3 binding site at rs30973633 and four DEHP-induced beta-defensins (Defb42, Defb30, Defb47 and Defb48). A DEHP-susceptibility allele in C57BL/6J contained five SNPs (rs28279710, rs32977910, rs46648903, rs46677594 and rs48287999) affecting SHP and six genes (Svs2, Svs3b, Svs4, Svs3a, Svs6 and Svs5) epigenetically silenced by DEHP. Finally, targeted experiments confirmed increased methylation in the Svs3ab promoter with decreased SEMG2 persisting across generations, providing a molecular explanation for the transgenerational sperm velocity decrease found in C57BL/6J after DEHP exposure. We conclude that the existence of SNP-dependent mechanisms in FVB/N inbred mice may confer resistance to transgenerational endocrine disruption.

The role of DEFB126 variation in male infertility and medically assisted reproduction technique outcome

RESEARCH QUESTION

Human DEFB126 is an important component of the glycocalyx of human spermatozoa. Beta-defensins play a primary role in male infertility due to their involvement in maturation and capacitation of spermatozoa. A 2-nt deletion of DEFB126 affects sperm function and so this study investigated the possible association between DEFB126 variants and its protein expression on medically assisted reproduction (MAR) technique outcome in Iranian infertile males.

DESIGN

The presence of a 2-nt deletion of DEFB126, and its protein expression in spermatozoa, were investigated by standard polymerase chain reaction (PCR) sequencing and immunocytochemistry, respectively. MAR technique outcome according to clinical pregnancy rates was assessed in 277 Iranian males with unexplained infertility, including 139 patients who underwent intrauterine insemination (IUI) and 103 patients who underwent IVF/intracytoplasmic sperm injection (ICSI), as well as 35 infertile males who declined to use any MAR treatment. As the control group, 100 fertile males with a normal spermiogram were enrolled.

RESULTS

The 2-nt deletion of DEFB126 was significantly higher in infertile patients than controls (P ≤ 0.05). The presence of this deletion resulted in significantly lower clinical pregnancy rates following IUI (P ≤ 0.05); however, there were no differences in IVF/ICSI outcomes according to genotype. The protein expression in del/del males was also remarkably lower than that of the other genotypes.

CONCLUSIONS

This sequence variation of DEFB126 may impair male reproductive function and can be related to male infertility. Interestingly, males with the del/del genotype have a normal spermiogram; however, their spermatozoa are evidently functionally impaired, which can affect IUI treatment outcome, but not treatment by IVF/ICSI.

DICER1 regulates antibacterial function of epididymis by modulating transcription of β-defensins

DICER1 is a key enzyme responsible for the maturation of microRNAs. Recent evidences suggested that DICER1 and microRNAs expressed in epididymis were involved in the control of male fertility. However, the exact mechanism remains to be elucidated. Here, we created a mouse line by targeted disruption of Dicer1 gene in the principal cells of distal caput epididymis. Our data indicated that a set of β-defensin genes were downregulated by DICER1 rather than by microRNAs. Moreover, DICER1 was significantly enriched in the promoter of β-defensin gene and controlled transcription. Besides, the antibacterial ability of the adult epididymis significantly declined upon Dicer1 deletion both in vitro and in vivo. And a higher incidence of reproductive defect was observed in middle-aged Dicer1-/- males. These results suggest that DICER1 plays an important role in transcription of β-defensin genes, which are associated with the natural antibacterial properties in a microRNA-independent manner, and further impacts the male fertility.

β-defensins and the epididymis: contrasting influences of prenatal, postnatal, and adult scenarios

β-defensins are components of host defense, with antimicrobial and pleiotropic immuno-modulatory properties. Research over the last 15 years has demonstrated abundant expression of a variety of β-defensins in the postnatal epididymis of different species. A gradient of region- and cell-specific expression of these proteins is observed in the epithelium of the postnatal epididymis. Their secretion into the luminal fluid and binding to spermatozoa as they travel along the epididymis has suggested their involvement in reproduction-specific tasks. Therefore, continuous attention has been given to various β-defensins for their role in sperm function and fertility. Although β-defensins are largely dependent on androgens, the underlying mechanisms regulating their expression and function in the epididymis are not well understood. Recent investigation has pointed out to a new and interesting scenario where β-defensins emerge with a different expression pattern in the Wolffian duct, the embryonic precursor of the epididymis, as opposed to the adult epididymis, thereby redefining the concept concerning the multifunctional roles of β-defensins in the developing epididymis. In this review, we summarize some current views of β-defensins in the epididymis highlighting our most recent data and speculations on their role in the developing epididymis during the prenatal-to-postnatal transition, bringing attention to the many unanswered questions in this research area that may contribute to a better understanding of epididymal biology and male fertility.

Effect of Lipopolysaccharide (LPS) Exposure on the Reproductive Organs of Immature Female Rats

Lipopolysaccharide (LPS), an endotoxin, elicits strong immune responses in mammals. Several lines of evidence demonstrate that LPS challenge profoundly affects female reproductive function. For example, LPS exposure affects steroidogenesis and folliculogenesis, resulting in delayed puberty onset. The present study was conducted to clarify the mechanism underlying the adverse effect of LPS on the delayed puberty in female rats. LPS was daily injected for 5 days (50 μg/kg, PND 25-29) to treated animals and the date at VO was evaluated through daily visual examination. At PND 39, animals were sacrificed, and the tissues were immediately removed and weighed. Among the reproductive organs, the weights of the ovaries and oviduct from LPS-treated animals were significantly lower than those of control animals. There were no changes in the weights of uterus and vagina between the LPS-treated and their control animals. Immunological challenge by LPS delayed VO. Multiple corpora lutea were found in the control ovaries, indicating ovulations were occurred. However, none of corpus luteum was present in the LPS-treated ovary. The transcription level of steroidogenic acute regulatory protein (StAR), CYP11A1, CYP17A1 and CYP19 were significantly increased by LPS treatment. On the other hand, the levels of 3β- HSD, 17β-HSD and LH receptor were not changed by LPS challenge. In conclusion, the present study demonstrated that the repeated LPS exposure during the prepubertal period could induce multiple alterations in the steroidogenic machinery in ovary, and in turn, delayed puberty onset. The prepubertal LPS challenge model used in our study is useful to understand the reciprocal regulation of immune (stress) - reproductive function in early life.

Epididymitis: revelations at the convergence of clinical and basic sciences

Acute epididymitis represents a common medical condition in the urological outpatient clinic. Mostly, epididymitis is caused by bacterial ascent through the urogenital tract, with pathogens originating either from sexually transmitted diseases or urinary tract infections. Although conservative antimicrobial therapy is possible in the majority of patients and is usually sufficient to eradicate the pathogen, studies have shown persistent oligozoospermia and azoospermia in up to 40% of these patients. Animal models of epididymitis are created to delineate the underlying reasons for this observation and the additional impairment of sperm function that is often associated with the disease. Accumulated data provide evidence of a differential expression of immune cells, immunoregulatory genes and pathogen-sensing molecules along the length of the epididymal duct. The evidence suggests that a tolerogenic environment exists in the caput epididymidis, but that inflammatory responses are most intense toward the cauda epididymidis. This is consistent with the need to provide protection for the neo-antigens of spermatozoa emerging from the testis, without compromising the ability to respond to ascending infections. However, severe inflammatory responses, particularly in the cauda, may lead to collateral damage to the structure and function of the epididymis. Convergence of the clinical observations with appropriate animal studies should lead to better understanding of the immunological environment throughout the epididymis, the parameters underlying susceptibility to epididymitis, and to therapeutic approaches that can mitigate epididymal damage and subsequent fertility problems.

Novel phenotype of mouse spermatozoa following deletion of nine β-defensin genes

β-defensin peptides are a large family of antimicrobial peptides. Although they kill microbes in vitro and interact with immune cells, the precise role of these genes in vivo remains uncertain. Despite their inducible presence at mucosal surfaces, their main site of expression is the epididymis. Recent evidence suggests that a major function of these peptides is in sperm maturation. In addition to previous work suggesting this, work at the MRC Human Genetics Unit, Edinburgh, has shown that homozygous deletion of a cluster of nine β-defensin genes in the mouse results in profound male sterility. The spermatozoa derived from the mutants had reduced motility and increased fragility. Epididymal spermatozoa isolated from the cauda region of the homozygous mutants demonstrated precocious capacitation and increased spontaneous acrosome reactions compared with those from wild-types. Despite this, these mutant spermatozoa had reduced ability to bind to the zona pellucida of oocytes. Ultrastructural examination revealed a disintegration of the microtubule structure of mutant-derived spermatozoa isolated from the epididymal cauda region, but not from the caput. Consistent with premature acrosome reaction and hyperactivation, spermatozoa from mutant animals had significantly increased intracellular calcium content. This work demonstrates that in vivo β-defensins are essential for successful sperm maturation, and that their disruption alters intracellular calcium levels, which most likely leads to premature activation and spontaneous acrosome reactions that result in hyperactivation and loss of microtubule structure of the axoneme. Determining which of the nine genes are responsible for the phenotype and the relevance to human sperm function is important for future work on male infertility.

Dynamic changes in the spatio-temporal expression of the β-defensin SPAG11C in the developing rat epididymis and its regulation by androgens

Herein, we characterized the spatio-temporal expression, cellular distribution and regulation by androgens of the β-defensin SPAG11C, the rat ortholog of the human SPAG11B isoform C, in the developing epididymis by using RT-PCR, in situ hybridization and immunohistochemistry. We observed that Spag11c mRNA was ubiquitously expressed in rat fetuses, but preferentially detected in male reproductive tissues at adulthood. SPAG11C (mRNA and protein) was prenatally mainly detected in the mesenchyme of the Wolffian duct, switching gradually after birth to a predominant localization in the epididymis epithelium during postnatal development. In the adult epididymis, smooth muscle and interstitial cells were also identified as sources of SPAG11C. Furthermore, SPAG11C was differentially immunolocalized on spermatozoa surface during their transit from testis throughout caput and cauda epididymis. Developmental and surgical castration studies suggested that androgens contribute to the epididymal cell type- and region-specific modulation of SPAG11C mRNA levels and immunolocalization. Together our findings provide novel insights into the potential role of β-defensins in the epididymis.

Another functional frame-shift polymorphism of DEFB126 (rs11467497) associated with male infertility

DEFB126 rs140685149 mutation was shown to cause sperm dysfunction and subfertility. Indel rs11467497 is another 4-nucleotide frame-shift mutation (151bp upstream of rs140685149) that leads to the premature termination of translation and the expression of peptide truncated at the carboxyl terminus. In the present study, we performed a comprehensive association study to check the contribution of rs140685149 and rs11467497 to male infertility. Our results confirmed the previous findings that there was no association between rs140685149 and sperm motility. In contrast, we found a significant association of another indel rs11467497 with male infertility. Moreover, rs11467497 was shown to be associated with higher number of round cells in the infertile males with low sperm motility. Surprisingly, the two mutations commonly existed in the sperm donors (n = 672), suggesting a potential application of the two indels in the screening for eligible sperm donors. Western blotting assays showed the sperms with rs140685149 2-nt deletion tended to have unstable DEFB126 protein in contrast of no DEFB126 protein expressed in the sperms with rs11467497 4-nt deletion, suggesting a more severe consequence caused by rs11467497 mutation. In conclusion, our study presented a significant contribution of another functional frame-shift polymorphism of DEFB126 (rs11467497) to male infertility.

The blood-epididymis barrier and inflammation

The blood-epididymis barrier (BEB) is a critical structure for male fertility. It enables the development of a specific luminal environment that allows spermatozoa to acquire both the ability to swim and fertilize an ovum. The presence of tight junctions and specific cellular transporters can regulate the composition of the epididymal lumen to favor proper sperm maturation. The BEB is also at the interface between the immune system and sperm. Not only does the BEB protect maturing spermatozoa from the immune system, it is also influenced by cytokines released during inflammation, which can result in the loss of barrier function. Such a loss is associated with an immune response, decreased sperm functions, and appears to be a contributing factor to post-testicular male infertility. Alterations in the BEB may be responsible for the formation of inflammatory conditions such as sperm granulomas. The present review summarizes current knowledge on the morphological, physiological and pathological components associated with the BEB, the role of immune function on the regulation of the BEB, and how disturbance of these factors can result in inflammatory lesions of the epididymis.

Transcriptional regulation of the rat sperm-associated antigen 11e (Spag 11e) gene during endotoxin challenge

The lipopolysaccharide (LPS) inducible expression of antimicrobial proteins of the Sperm-Associated Antigen 11 (Spag11) family is dependent on nuclear factor-κB (NF-κB) activation and epigenetic factors. However, the regulatory mechanisms that govern their gene expression during endotoxin challenge are unknown. In this study, we demonstrate that the Spag11e gene upstream sequence contains binding sites for androgen receptor (AR), NF-κB, nuclear factor-1, E-twenty-six and activator protein 2. The role of these transcription factors in inducing Spag11e gene during LPS challenge was analysed by measuring luciferase activity in HEK cells transiently transfected with deletion constructs that lacked one or more of the binding sites. Deletion of AR-binding site resulted in loss of luciferase activity and no further decrease was observed when progressive deletions of the other transcription factor binding sites were made. Mutations in AR or NF-κB binding site resulted in loss of luciferase activity. Electrophoretic gel-mobility shift assays indicated that AR and NF-κB proteins bind to the synthesised radio-labelled oligomers used as probes and the mobility shifted when respective antibodies were added. Results of this study indicate the direct involvement of AR and NF-κB in LPS-induced Spag11e expression, thereby expanding our understanding of antimicrobial gene expression during endotoxin challenge.

Effect of chocolate and Propolfenol on rabbit spermatogenesis and sperm quality following bacterial lipopolysaccharide treatment

The aims of the study were to evaluate the effects of chocolate and propolis-enriched diets on rabbit spermatogenesis, sperm motility, and ultrastructure following bacterial lipopolysaccharide (LPS) treatment. Thirty-two New Zealand White rabbits were divided into four groups. The LPS-Propolfenol(®) group received propolis (500 mg/kg/day) in their diet for 15 days, while the LPS-chocolate group was fed 70% cacao chocolate (1 g/1 kg/day) for the same period. Following the diet treatments, rabbits in the LPS-Propolfenol(®) and LPS-chocolate groups, and an LPS group received a single intraperitoneal dose of 50 μg/kg LPS, and the control group received only saline. Kinematic sperm traits were evaluated with a computer assisted sperm analyzer (CASA) system, and ultrastructural characteristics were examined by transmission electron microscopy (TEM). Testicular and epididymal tissues were observed by light microscopy and TEM and multiplex real time reverse transcriptase-polymerase chain reaction (RT-PCR) assay was used to detect and quantify toll-like receptor-4 (TLR-4) gene expression. The values of the analyzed semen parameters of rabbits treated with LPS-Propolfenol(®) and LPS-chocolate did not show any variations compared with the control group, but they were lower in rabbits treated only with LPS. Alterations observed in the testicular tissue of LPS treated-rabbits were not detected in specimens from the LPS-chocolate and LPS-Propolfenol(®) groups, which showed normal spermatogenesis. The TLR-4 mRNA expression was similar in controls, in LPS treated, and in LPS-chocolate groups, but it was significantly (p < 0.01) decreased in LPS-Propolfenol(®) rabbits. In conclusion, a chocolate and propolis-enriched diet showed a protective effect on the spermatogenetic process of buck rabbits following LPS treatment.

Experimental Escherichia coli epididymitis in rats: assessment of testicular involvement in a long-term follow-up

The objective of this study was to investigate spermatogenesis and testicular inflammation in a rat model of unilateral Escherichia coli epididymitis in a long-term follow-up. Unilateral epididymitis was induced in 30 Sprague-Dawley rats by injecting E. coli into the right ductus deferens. Oral antimicrobial treatment with sparfloxacin (50 mg kg(-1) body weight/7 days) was administered in half of the animals 24 h after infection. Five treated and five untreated rats were killed at 2 weeks, 3 months and 6 months after infection. Spermatogenesis was investigated using a histological semi-quantitative score. The presence of inflammatory cells (B- and T lymphocytes, macrophages and granulocytes) in the testicular tissues was evaluated by immunohistochemistry. The testes were sterile at all times. Over the course of 6 months, spermatogenesis underwent significant incremental impairment on the inoculated side as compared to the contralateral side (P < 0.001). However, overall spermatogenesis scores were not significantly different between treated and untreated animals (P > 0.3 at each time point). Finally, loss of testicular architecture on the inoculated side was not associated with any cellular inflammatory response. Thus, adjuvant therapies need to be studied, and research is necessary on how to prevent deterioration of testicular function in bacterial epididymitis.

All-trans-retinoic acid ameliorates the inflammation by inducing transforming growth factor beta 1 and interleukin 10 in mouse epididymitis

PROBLEM

Epididymitis, one of the most common urological diseases, can lead to the destruction of the epididymal duct and cause transient or permanent sterility. The aim of this study was to investigate the functions and related mechanisms of all trans retinoic acid (atRA) in alleviating the acute inflammation of epididymitis.

METHOD OF STUDY

The mouse model of the epididymitis was induced by injecting Escherichia coli into the cauda epididymis. atRA was administrated for five consecutive days through intraperitoneal injection. The expression levels of inflammatory cytokines were measured by real-time PCR and Western blot. In addition, cultured primary mouse epididymal epithelial cells were treated with different concentrations of atRA and RAR antagonists to identify whether the effect of atRA was mediated through RAR.

RESULTS

Our results demonstrate that atRA ameliorates the inflammation in mouse epididymitis by decreasing the expression of the pro-inflammatory cytokines and increasing the expression of anti-inflammatory factors including TGF-β1 and IL-10. Our results show that the upregulating effect of atRA on TGF-β1 was mediated by RARα, and the enhancing effect of atRA on IL-10 expression was mediated via RARβ.

CONCLUSION

These new results suggest that atRA is involved in regulating the inflammatory response of epididymis.

Bovine β-defensin gene family: opportunities to improve animal health?

Recent analysis of the bovine genome revealed an expanded suite of β-defensin genes that encode what are referred to as antimicrobial or host defense peptides (HDPs). Whereas primate genomes also encode α- and θ-defensins, the bovine genome contains only the β-defensin subfamily of HDPs. β-Defensins perform diverse functions that are critical to protection against pathogens but also in regulation of the immune response and reproduction. As the most comprehensively studied subclass of HDPs, β-defensins possess the widest taxonomic distribution, found in invertebrates as well as plants, indicating an ancient point of origin. Cross-species comparison of the genomic arrangement of β-defensin gene repertoire revealed them to vary in number among species presumably due to differences in pathogenic selective pressures but also genetic drift. β-Defensin genes exist in a single cluster in birds, but four gene clusters exist in dog, rat, mouse, and cow. In humans and chimpanzees, one of these clusters is split in two as a result of a primate-specific pericentric inversion producing five gene clusters. A cluster of β-defensin genes on bovine chromosome 13 has been recently characterized, and full genome sequencing has identified extensive gene copy number variation on chromosome 27. As a result, cattle have the most diverse repertoire of β-defensin genes so far identified, where four clusters contain at least 57 genes. This expansion of β-defensin HDPs may hold significant potential for combating infectious diseases and provides opportunities to harness their immunological and reproductive functions in commercial cattle populations.

Structural and functional integrity of spermatozoa is compromised as a consequence of acute uropathogenic E. coli-associated epididymitis

Uropathogenic Escherichia coli (UPEC)-associated epididymitis is commonly diagnosed in outpatient settings. Although the infection can be successfully cleared using antimicrobial medications, 40% of patients unexplainably show persistent impaired semen parameters even after treatment. Our aim was to investigate whether pathogenic UPEC and its associated virulence factor hemolysin (hlyA) perturb the structural and functional integrity of both the epididymis and sperm, actions that may be responsible for the observed impairment and possibly a reduction of fertilization capabilities. Semen collected from patients diagnosed with E. coli-only related epididymitis showed that sperm counts were low 14 days postantimicrobial treatment regardless of hlyA status. At Day 84 following treatment, hlyA production correlated with approximately 4-fold lower sperm concentrations than in men with hlyA-negative strains. In vivo experiments with the hlyA-producing UPEC CFT073 strain in a murine epididymitis model showed that just 3 days postinfection, structural damage to the epididymis (epithelial damage, leukocyte infiltration, and edema formation) was present. This was more severe in UPEC CFT073 compared to nonpathogenic E. coli (NPEC 470) infection. Moreover, pathogenic UPEC strains prematurely activated the acrosome in vivo and in vitro. Raman microspectroscopy revealed that UPEC CFT073 undermined sperm integrity by inducing nuclear DNA damage. Consistent with these observations, the in vitro fertilization capability of hlyA-treated mouse sperm was completely abolished, although sperm were motile. These findings provide new insights into understanding the possible processes underlying clinical manifestations of acute epididymitis.

The novel human β-defensin 114 regulates lipopolysaccharide (LPS)-mediated inflammation and protects sperm from motility loss

Lipopolysaccharide (LPS) is an important pathological factor involved in serious inflammatory diseases and male reproductive impairments. Emerging evidence demonstrates that antimicrobial peptides possess protective activity in response to LPS-induced inflammation. However, the LPS-binding and/or immunosuppressive activity of β-defensins (DEFBs) has been underestimated. In the present work, we characterized a novel human defensin, DEFB114, which was expressed predominantly in the epididymis and gingival cells at the RNA level. Homogenous recombinant DEFB114 peptides were prepared and characterized using mass spectrometry. DEFB114 protein exhibited a broad spectrum of antimicrobial activity with salt sensitivity against typical pathogenic microbes (i.e. Escherichia coli, Staphylococcus aureus, and Candida albicans). Interestingly, DEFB114 demonstrated novel LPS-binding activity in vitro and inhibited TNF-α release in RAW264.7 cultures through the inhibition of MAPK p42/44 when challenged with LPS. Moreover, DEFB114 could also rescue the LPS-induced reduction of human sperm motility in vitro and protect d-galactosamine-sensitized C57BL/6 mice from LPS-induced lethality in vivo. The protective activity of DEFB114 on RAW264.7, human sperm, and the d-galactosamine-sensitized mice was disulfide bond-dependent because alkylated DEFB114 lost its activity. The low cytotoxicity of the DEFB114 peptide toward human erythrocytes is indicative of its potential therapeutic use in the treatment of LPS-induced inflammation, LPS contamination, and potentially septic shock.

Human beta-defensin DEFB126 is capable of inhibiting LPS-mediated inflammation

β-Defensins are cationic, antimicrobial peptides that participate in antimicrobial defense as well as the regulation of innate and adaptive immunity. Human β-defensin 126 (DEFB126) is a multifunctional glycoprotein consisting of a conserved β-defensin core and a unique long glycosylated peptide tail. The long glycosylated peptide tail has been proven to be critical for efficient transport of sperm in the female reproductive tract, preventing their immune recognition, and efficient delivery of capacitated sperm to the site of fertilization. However, the functions of the conserved β-defensin core remain to be fully elucidated. In the present work, the conserved β-defensin core of the DEFB126 was expressed to explore its potential antimicrobial and anti-inflammatory activities. The DEFB126 core peptide exhibited both high potency for binding and neutralizing lipopolysaccharide (LPS) in vitro, and potent anti-inflammatory ability by down-regulating the mRNA expression of pro-inflammatory cytokines including IL-α, IL-1β, IL-6 and TNF-α in a murine macrophage cell line RAW264.7. The treatment with the DEFB126 core peptide also led to correspondingly decreased secretion of IL-6 and TNF-α. The blockade of LPS-induced p42/44 and p38 MAPK signal pathway might contribute to the anti-inflammation effects of the DEFB126 core peptide. Furthermore, fluorescence-labeled DEFB126 could enter RAW 264.7 cells and reduce the production of LPS-stimulated inflammatory factors, implying that DEFB126 might also participate in intracellular regulation beyond its direct LPS neutralization. In summary, our results demonstrate that the DEFB 126 core peptide has critical functions in parallel to its C-terminal tail by showing LPS-binding activity, anti-inflammatory effects and intracellular regulatory function.