Proinflammatory and Oxidative Stress States Induced by Human Papillomavirus and Chlamydia trachomatis Coinfection Affect Sperm Quality in Asymptomatic Infertile Men

From infection to infertility: a review of the role of human papillomavirus-induced oxidative stress on reproductive health and infertility

Infertility has emerged as a significant global health concern, affecting nearby 8-12% of couples in reproductive age worldwide. Increasing evidence suggests a potential link between human papillomavirus (HPV) and infertility in both men and women. Some research indicate that HPV can infect various components of semen, potentially affecting sperm quality by decreasing motility, viability, and increasing DNA fragmentation, all of which may contribute to male infertility. The virus can attach to the equatorial region of the sperm head, enabling infected sperm to transmit the virus to the oocyte or placenta. Consequently, HPV potentially induces apoptosis in trophoblastic cells and disrupts their adhesion to endometrial cells, which raises the risk of miscarriage. HPV may also affect ovarian reserve by causing chronic inflammation, which can impair granulosa cell function and lower serum anti-Müllerian hormone (AMH) levels. Besides, HPV-related immune responses also contribute to infertility by producing anti-sperm antibodies (ASAs), which cause sperm clumping, reduce motility through cervical mucus, activate the complement system that damages sperm in the female reproductive tract and interfere with sperm-egg interactions. Moreover, HPV infection has been linked to reduced success rates in assisted reproductive technologies (ART), potentially disrupting critical processes such as the acrosome reaction, sperm-oocyte interaction, and fusion. One potential mechanism through which HPV contributes to infertility is oxidative stress (OS). Triggered OS can negatively impact sperm quality and cause damage to the female reproductive system, ultimately contributing to infertility. Despite these associations, the precise mechanisms and the strength of the relationship remain uncertain. Thus, this review seeks to investigate the potential impact of HPV on infertility, particularly its effects on the reproductive system through OS. A clearer understanding of these processes could inform future health strategies for addressing HPV-related infertility.

HPV and co-infections: impacts on semen inflammation, oxidative stress, and sperm quality

Introduction

Human papillomavirus (HPV) is the most common sexually transmitted viral infection worldwide, which has been suggested to induce male urogenital inflammation and affect fertility. However, reported evidence is scarce and inconclusive. Moreover, the putative effects of coinfections remain largely unexplored. This study aimed to analyze HPV male urogenital infection, both as a single infection and in conjunction with other common uropathogens, along with its impact on inflammatory biomarkers in semen, oxidative stress and sperm quality.

Methods

The prevalence of HPV urogenital infection and its coinfection with several other uropathogens was analyzed in a cohort of 205 men attending a urology clinic. Furthermore, levels of sperm leukocyte subsets and inflammatory cytokines, semen analysis, sperm apoptosis and necrosis, and sperm ROS production were assessed.

Results

A considerable prevalence (19%) of HPV male urogenital infection was found. Interestingly, HPV was detected coinfecting with at least one other uropathogen in most cases (74.4%). Notably, the most frequently detected coinfection was C. trachomatis (CT, 52% of cases). Remarkably, patients solely infected with HPV showed no significant alterations in conventional sperm quality parameters as well as reduced concentrations of IL-6 and leukocytes in semen. However, patients coinfected with HPV and CT showed significantly impaired sperm concentration and motility and increased levels of IL-6 in semen.

Conclusion

These results indicate that HPV infection alone does not associate with semen inflammation or major changes in sperm quality. However, co-infection with CT is associated with both semen inflammation and reduced sperm quality. This indicates that, besides being prevalent, concurrent HPV and CT infections in semen may represent a unique clinical entity with particular characteristics.

The possible pathogenic mechanisms of microorganisms in infertility: a narrative review

Infertility can harm a patient in physical, psychological, spiritual, and medical ways. This illness is unusual because it affects the patient's companion and the patient individually. Infertility is a multifactorial disease, and various etiological factors like infection are known to develop this disorder. Recently published studies reported that different bacteria, such as Chlamydia trachomatis, Mycoplasma spp., Ureaplasma urealyticum, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, can lead to infertility by immunopathological effects, oxidative stress, and adverse effects on sperm concentration, motility, morphology, and DNA condensation. Among viruses, Human papillomavirus and Herpes simplex virus reduce sperm progressive motility and sperm concentration. The viruses can lead to the atrophy of the germinal epithelium and degenerative changes in the testes. Candida albicans also harm sperm quality, motility, and chromatin integrity and induce apoptosis in sperm cells. Finally, Trichomonas vaginalis leads to distorted heads, broken necks, and acrosomes exocytosis in sperms. This parasite decreases sperm viability and functional integrity. Noteworthy, oxidative stress could have a role in many pathological changes in the reproductive system. Recent findings show that microorganisms can increase reactive oxygen species concentration inside the host cells, leading to oxidative stress and sperm distress and dysfunction. Therefore, this article explores the potential significance of critical bacteria linked to infertility and their pathogenic mechanisms that can affect sperm function and the female reproductive system.

Impact of human papillomavirus and coinfection with other sexually transmitted pathogens on male infertility

ABSTRACT

This study primarily aimed to investigate the prevalence of human papillomavirus (HPV) and other common pathogens of sexually transmitted infections (STIs) in spermatozoa of infertile men and their effects on semen parameters. These pathogens included Ureaplasma urealyticum, Ureaplasma parvum, Chlamydia trachomatis, Mycoplasma genitalium , herpes simplex virus 2, Neisseria gonorrhoeae, Enterococcus faecalis, Streptococcus agalactiae, Pseudomonas aeruginosa , and Staphylococcus aureus . A total of 1951 men of infertile couples were recruited between 23 March 2023, and 17 May 2023, at the Department of Reproductive Medicine of The First People's Hospital of Yunnan Province (Kunming, China). Multiplex polymerase chain reaction and capillary electrophoresis were used for HPV genotyping. Polymerase chain reaction and electrophoresis were also used to detect the presence of other STIs. The overall prevalence of HPV infection was 12.4%. The top five prevalent HPV subtypes were types 56, 52, 43, 16, and 53 among those tested positive for HPV. Other common infections with high prevalence rates were Ureaplasma urealyticum (28.3%), Ureaplasma parvum (20.4%), and Enterococcus faecalis (9.5%). The prevalence rates of HPV coinfection with Ureaplasma urealyticum, Ureaplasma parvum, Chlamydia trachomatis, Mycoplasma genitalium , herpes simplex virus 2, Neisseria gonorrhoeae, Enterococcus faecalis, Streptococcus agalactiae , and Staphylococcus aureus were 24.8%, 25.4%, 10.6%, 6.4%, 2.4%, 7.9%, 5.9%, 0.9%, and 1.3%, respectively. The semen volume and total sperm count were greatly decreased by HPV infection alone. Coinfection with HPV and Ureaplasma urealyticum significantly reduced sperm motility and viability. Our study shows that coinfection with STIs is highly prevalent in the semen of infertile men and that coinfection with pathogens can seriously affect semen parameters, emphasizing the necessity of semen screening for STIs.

The Human 8-oxoG DNA Glycosylase 1 (OGG1) Ser326Cys Polymorphism in Infertile Men

BACKGROUND/OBJECTIVES

8-hydroxy-2'-deoxyguanosine (8-OHdG) is a form of oxidative DNA damage caused by oxidative stress (OS), which is considered a major factor in male infertility. The cellular defense system against 8-OHdG involves base excision repair (BER) with the enzyme 8-Oxoguanine DNA glycosylase 1 (OGG1). However, studies on the single-nucleotide polymorphism (SNP) OGG1 Ser326Cys have demonstrated that the Cys326Cys genotype could be the cause of an increment in oxidative DNA damage. In this study, the OGG1 Ser326Cys polymorphism and its effect on DNA oxidation were evaluated in 118 infertile men.

METHODS

Polymorphic screening was performed using TaqMan allelic discrimination assays, and oxidative DNA damage was evaluated through the quantification of 8-OHdG and total antioxidant capacity (TAC); in addition, electrical bioimpedance spectroscopy (EBiS) measurements were used as a reference for different electrical properties associated with 8-OHdG concentrations.

RESULTS

The detected Cys (G) allele frequency (0.4) was higher compared to the allele frequency reported in the "Allele Frequency Aggregator" (ALFA) and "Haplotype Map" (HapMap) projects for American populations (0.21-0.29), suggesting that the Cys (G) allele carrier could be a factor associated with American infertile populations. The values of 8-OHdG were twofold higher in carriers of the Cys326Cys (GG) genotype than the other genotypes and, in concordance, the TAC levels were threefold lower in Cys326Cys (GG) genotype carriers compared to the other genotypes. Moreover, the EBiS magnitude exhibited potential for the detection of different oxidative damage in DNA samples between genotypes.

CONCLUSIONS

The Cys326Cys (GG) genotype is associated with oxidative DNA damage that could contribute to male infertility.

Impact of high-risk and low-risk human papillomavirus infections on the male genital tract: effects on semen inflammation and sperm quality

Human Papillomavirus (HPV), a prevalent sexually transmitted infection, comprises high-risk (HR-HPV) and low-risk (LR-HPV) viruses, the former posing a high risk for developing malignancies whereas the latter mainly for benign warts. Despite increasing awareness of HPV's impact on men's health, the influence of HR-HPV and LR-HPV urogenital infections on male fertility potential remains uncertain. This study aimed to investigate whether male urogenital infection with HR- or LR-HPV associates with impaired sperm quality, oxidative stress, and inflammation. A total of 205 male patients attending an urology clinic were enrolled. Semen samples were analyzed for HPV using PCR and genotyped by RFLP. Semen quality was evaluated following WHO guidelines. Semen leukocytes, reactive oxygen species (ROS), and sperm viability were analyzed using flow cytometry. HPV was detected in 19% (39/205) of semen samples. HR-HPV infections were more prevalent, with HPV-16 being the most frequent genotype. Neither HR-HPV nor LR-HPV were associated with significant alterations in routine sperm quality parameters. However, HR-HPV+ individuals showed significantly higher levels of sperm necrosis and exhibited increased proportions of ROS+ spermatozoa compared to LR-HPV+ or control individuals. Furthermore, no significant semen inflammation was detected in patients infected with either HR-HPV or LR-HPV, and unexpectedly reduced semen leukocytes and inflammatory cytokines (IL-6 and IL-1β) were observed in HR-HPV+ patients compared to controls. These observations underscore the importance of comprehensive HPV screening, including genotyping, in urology and fertility clinics to understand the progression of the infection, potential adverse effects on reproductive health, and the oncogenic risks involved.

Molecular detection of transcriptionally active ovine papillomaviruses in commercial equine semen

Virological evaluation was performed on equine semen to detect the presence of papillomaviruses (PVs) using droplet digital polymerase chain reaction (ddPCR) as the aim of this study was to investigate whether the sperm from asymptomatic stallions harbors ovine papillomaviruses (OaPVs). Twenty-seven semen samples were analyzed, 18 of which were commercially acquired. The remaining nine samples comprising semen and peripheral blood, were collected from nine stallions with no apparent signs of PV-related diseases during clinical examination at the Didactic Veterinary University Hospital (DVUH) of Naples. OaPV was detected in 26 semen samples. OaPV1 was the most prevalent virus infecting equine semen. OaPV1 infected 21 semen samples (~80.8%) and showed a high number of DNA and RNA copies per microliter. qPCR was used to detect OaPV1 DNA in the 18 semen samples. ddPCR was used to detect and quantify the expression of OaPV2, OaPV3, and OaPV4. qPCR failed to detect DNA for these genotypes. Additionally, ddPCR was used to detect the transcriptionally active OaPV1 in six blood and semen samples from the same stallion. ddPCR failed to detect any nucleic acids in OaPVs in peripheral blood samples from the three stallions. In one semen sample, ddPCR detected OaPV1 DNA but failed to detect any nucleic acid in the remaining two semen samples, and peripheral blood from the same animals of the remaining 18 semen samples was not available, OaPV1 and OaPV4 were responsible for nine and five single infections, respectively. No single infections with either OaPV3 or OaPV4 were seen.

Emerging paradigms: unmasking the role of oxidative stress in HPV-induced carcinogenesis

The contribution of the human papillomavirus (HPV) to cancer is significant but not exclusive, as carcinogenesis involves complex mechanisms, notably oxidative stress. Oxidative stress and HPV can independently cause genome instability and DNA damage, contributing to tumorigenesis. Oxidative stress-induced DNA damage, especially double-strand breaks, aids in the integration of HPV into the host genome and promotes the overexpression of two viral proteins, E6 and E7. Lifestyle factors, including diet, smoking, alcohol, and psychological stress, along with genetic and epigenetic modifications, and viral oncoproteins may influence oxidative stress, impacting the progression of HPV-related cancers. This review highlights various mechanisms in oxidative-induced HPV-mediated carcinogenesis, including altered mitochondrial morphology and function leading to elevated ROS levels, modulation of antioxidant enzymes like Superoxide Dismutase (SOD), Glutathione (GSH), and Glutathione Peroxidase (GPx), induction of chronic inflammatory environments, and activation of specific cell signaling pathways like the Phosphoinositide 3-kinase, Protein kinase B, Mammalian target of rapamycin (PI3K/AKT/mTOR) and the Extracellular signal-regulated kinase (ERK) signaling pathway. The study highlights the significance of comprehending and controlling oxidative stress in preventing and treating cancer. We suggested that incorporating dietary antioxidants and targeting cancer cells through mechanisms involving ROS could be potential interventions to mitigate the impact of oxidative stress on HPV-related malignancies.

DNA damage in testicular germ cells and spermatozoa. When and how is it induced? How should we measure it? What does it mean?

This review surveys the causes and consequences of DNA damage in the male germ line from spermatogonial stem cells to fully differentiated spermatozoa. Within the stem cell population, DNA integrity is well maintained as a result of excellent DNA surveillance and repair; however, a progressive increase in background mutation rates does occur with paternal age possibly as a result of aberrant DNA repair as well as replication error. Once a germ cell has committed to spermatogenesis, it responds to genetic damage via a range of DNA repair pathways or, if this process fails, by the induction of apoptosis. When fully-differentiated spermatozoa are stressed, they also activate a truncated intrinsic apoptotic pathway which results in the activation of nucleases in the mitochondria and cytoplasm; however, the physical architecture of these cells prevents these enzymes from translocating to the nucleus to induce DNA fragmentation. Conversely, hydrogen peroxide released from the sperm midpiece during apoptosis is able to penetrate the nucleus and induce DNA damage. The base excision repair pathway responds to such damage by cleaving oxidized bases from the DNA, leaving abasic sites that are alkali-labile and readily detected with the comet assay. As levels of oxidative stress increase and these cells enter the perimortem, topoisomerase integrated into the sperm chromatin becomes activated by SUMOylation. Such activation may initially facilitate DNA repair by reannealing double strand breaks but ultimately prepares the DNA for destruction by nucleases released from the male reproductive tract. The abasic sites and oxidized base lesions found in live spermatozoa are mutagenic and may increase the mutational load carried by the offspring, particularly in the context of assisted conception. A variety of strategies are described for managing patients expressing high levels of DNA damage in their spermatozoa, to reduce the risks such lesions might pose to offspring health.

When Bacteria and Viruses Collide: A Tale of Chlamydia trachomatis and Sexually Transmitted Viruses

The global incidence of sexually transmitted infections (STIs) remains high, with the World Health Organization (WHO) estimating that over 1 million people acquire STIs daily. STIs can lead to infertility, pregnancy complications, and cancers. Co-infections with multiple pathogens are prevalent among individuals with an STI and can lead to heightened infectivity and more severe clinical manifestations. Chlamydia trachomatis (CT) is the most reported bacterial STI worldwide in both men and women, and several studies have demonstrated co-infection of CT with viral and other bacterial STIs. CT is a gram-negative bacterium with a unique biphasic developmental cycle including infectious extracellular elementary bodies (EBs) and metabolically active intracellular reticulate bodies (RBs). The intracellular form of this organism, RBs, has evolved mechanisms to persist for long periods within host epithelial cells in a viable but non-cultivable state. The co-infections of CT with the most frequently reported sexually transmitted viruses: human immunodeficiency virus (HIV), human papillomavirus (HPV), and herpes simplex virus (HSV) have been investigated through in vitro and in vivo studies. These research studies have made significant strides in unraveling the intricate interactions between CT, these viral STIs, and their eukaryotic host. In this review, we present an overview of the epidemiology of these co-infections, while specifically delineating the underlying mechanisms by which CT influences the transmission and infection dynamics of HIV and HSV. Furthermore, we explore the intricate relationship between CT and HPV infection, with a particular emphasis on the heightened risk of cervical cancer. By consolidating the current body of knowledge, we provide valuable insights into the complex dynamics and implications of co-infection involving CT and sexually transmitted viruses.

The initial interplay between HIV and mucosal innate immunity

Human Immunodeficiency Virus (HIV) is still one of the major global health issues, and despite significant efforts that have been put into studying the pathogenesis of HIV infection, several aspects need to be clarified, including how innate immunity acts in different anatomical compartments. Given the nature of HIV as a sexually transmitted disease, one of the aspects that demands particular attention is the mucosal innate immune response. Given this scenario, we focused our attention on the interplay between HIV and mucosal innate response: the different mucosae act as a physical barrier, whose integrity can be compromised by the infection, and the virus-cell interaction induces the innate immune response. In addition, we explored the role of the mucosal microbiota in facilitating or preventing HIV infection and highlighted how its changes could influence the development of several opportunistic infections. Although recent progress, a proper characterization of mucosal innate immune response and microbiota is still missing, and further studies are needed to understand how they can be helpful for the formulation of an effective vaccine.

Effects of Ureaplasma urealyticum infection on semen quality and sperm morphology

INTRODUCTION

Ureaplasma urealyticum (U. urealyticum) infection is primarily associated with damage to male fertility through its effects on male sperm parameters. However, its effects on sperm semiological variables remain unclear. Therefore, this study aimed to investigate whether U. urealyticum infection was associated with semen quality and sperm morphology.

METHODS

From 2019 to 2021, this cross-sectional study analyzed infective pathogens and semen variables in 1064 males (22-30 years old) recruited from our reproductive center and the general public. Routine semen parameters and normal sperm morphology rate were analyzed using methods outlined by the World Health Organization. The associations between semen quality, sperm morphology, and U. urealyticum infection were studied using general linear models.

RESULTS

The participants were categorized into three groups: (i) U. urealyticum infection (n=328), (ii) non-U. urealyticum infection (including males with urogenital tract infection symptoms but no U. urealyticum detected in their semen samples, n=377), and (iii) normal volunteers (males without symptoms of urogenital tract infection and no pathogens detected in semen samples, n=359). U. urealyticum in semen samples was observed to be associated with lower sperm concentrations (p<0.001) and a lower ratio of anterograde motile spermatozoa (p<0.001). Semen cultures positive for U. urealyticum were associated with lower normal sperm morphology (p<0.001) compared to semen cultures negative for U. urealyticum.

CONCLUSION

This study shows the importance of proper investigations for U. urealyticum during routine clinical examinations and diagnoses of males with infertility.

Detection of Chlamydia trachomatis inside spermatozoa using flow cytometry: Effects of antibiotic treatment (before and after) on sperm count parameters

There is increasing evidence that Chlamydia trachomatis (CT) infection can directly affect male fertility. However, only few have investigated the effects of CT on semen parameters, and mostly with inconclusive results. The main aims of this study were to identify CT inside spermatozoa, and the possible pre and post antibiotic treatment effects on the overall semen parameters. We developed a flow cytometric method for the detection of CT inside spermatozoa (SPI™). Briefly, sperm cells were fixed, membrane permeabilized and DNA was loosened using DNAse. Sperm cells were incubated with a primary monoclonal antibody against CT and with a secondary fluorescent antibody (vs primary), and analysed using a flow cytometer. Of 2415 infertile individuals, 48.61% were found positive for CT. 170 CT+ samples were included in the CT antibiotic treatment study. 78.82% (134/170) of the CT+ showed a significant reduction in the percentage of the iCT infected spermatozoa after the antibiotic treatment; 59.70% (80/134) decreased to non-detectable levels. Spermcount data were also recorded. Spermatozoa morphology (normal and teratozoospermia index, TZI) and motility (fast progressive and non-progressive spermatozoa) were statistically significant altered in CT+ pre-treatment vs control group. CT antibiotic treatment showed statistically significant effects on normal spermatozoa morphology, mid-piece and tail defects, and TZI. The study demonstrated that semen flow cytometric analysis of semen could be a valuable tool for faster and accurate identification of individuals with asymptomatic CT infection. It also identified a positive effect of antibiotic therapy on semen parameters, that could help males with infertility.

Herpes simplex virus type 2 seroprevalence and associated factors in fertility-treatment-seeking population: A cross-sectional survey in the United Arab Emirates

Background

Herpes simplex virus type 2 (HSV-2) is a common genitally-transmitted viral infection affecting more than 400 million individuals globally. In the United Arab Emirates (UAE), in specific at-risk population groups, the burden of HSV-2 has not been reported. This study investigated the prevalence of HSV-2 IgG antibodies in patients seeking fertility treatment and characterized patients with seropositivity to HSV-2 IgG antibodies.

Methodology

A cross-sectional sample of patients seeking fertility treatment in a major fertility clinic in Abu Dhabi, UAE was surveyed from April to May 2021. Patients were consecutively invited to complete self-administered questionnaires and provide blood for HSV-2 testing. Information on sociodemographics, medical history, and infertility was collected. Serum specimens were screened using an enzyme-linked immunosorbent assay for HSV-2 IgG antibodies detection.

Results

Two hundred and ninety-nine patients were surveyed and provided blood samples. The mean age of the patients was 35.9 ± 6.8 [mean ± standard deviation (SD)] years with 89.3% being women. Sixty-six percent were overweight or obese, 25.0% had at least one chronic comorbidity, and 19.6% reported ever-had genital infection. More than two-thirds (68.3%) of the patients were infertile for ≥ 6 months. Of the 42 infertile males, 69.0% had an abnormal semen analysis. HSV-2 IgG antibodies was detected in 12.4% of patients. The HSV-2 IgG seropositive patients had a higher mean age (39.5 vs. 35.4 years; p < 0.001) compared to seronegative patients. HSV-2 IgG antibodies seropositivity was more common in males (15.6%) than females (12.0%), in patients with secondary (14.1%) vs. primary (9.2%) infertility, or in males with abnormal (10.3%) vs. normal (7.7%) semen.

Conclusion

Exposure to HSV-2 at any time in patients seeking fertility treatment in the UAE was found to be slightly common in more than one out of 10 patients. Tailored health campaigns on HSV-2 prevention are warranted.

Semen Quality Following Long-term Occupational Exposure to Formaldehyde in China

IMPORTANCE

The potential effects of long-term occupational exposure to formaldehyde (FA) on human semen quality is not clear.

OBJECTIVE

To assess whether long-term occupational exposure to FA is associated with semen quality.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study was conducted from June 1 to June 30, 2021, in Xi'an, China. Participants were adults aged 23 to 40 years who had lived in the study area for 24 months or longer. Data analysis was performed from September 1 to October 1, 2021.

EXPOSURES

Long-term occupational exposure to FA was measured using a formaldehyde detector, and the FA exposure index (FEI) was calculated as follows: FEI = final concentration of FA (mg/m3) × work time during a workday (hour) × cumulative workdays (year).

MAIN OUTCOMES AND MEASURES

Semen samples were collected by masturbation after 3 to 7 days of abstinence and were then assessed by the computer-automated semen analysis system, Baso-Papanicolaou staining, and sperm-chromatin structure assay.

RESULTS

A total of 205 men (mean [SD] age, 29.49 [3.64] years), with 124 individuals in the FA exposure group (mean [SD] FEI, 73.72 [54.86]) and 81 age-matched controls, were included in the final analysis. Long-term personal occupational exposure to FA was significantly associated with poor semen quality. Specifically, a 1-unit increase in FEI was associated with a change of -0.99% (95% CI, -1.00% to -0.98%) in total sperm motility, -0.99% (95% CI, -0.99% to -0.97%) in progressive sperm motility, -0.05% (95% CI, -0.08% to -0.02%) in curvilinear velocity, -0.07% (95% CI, -0.10% to -0.04%) in straight line velocity, -0.07% (95% CI, -0.10% to -0.04%) in time-average velocity, -0.98% (95% CI, -0.99% to -0.93%) in normal sperm morphology, -0.24% (95% CI, -0.35% to -0.11%) in seminal neutral glucosidase, -0.61% (95% CI, -0.66% to -0.56%) in seminal plasma zinc, 0.52% (95% CI, 0.15% to 1.02%) in beat cross frequency, and 0.10% (95% CI, 0.06% to 0.14%) in the DNA fragmentation index. These associations remained significant after adjusting for confounding factors. Furthermore, subgroup analysis found that high levels of oxidative stress might promote the associations between FA exposure and semen quality.

CONCLUSIONS AND RELEVANCE

This study found an association between long-term occupational exposure to FA and semen quality. This deterioration was dose and time dependent and might be induced by oxidative stress.

Bacteriospermia - A formidable player in male subfertility

Bacterial colonization of male reproductive tissues, cells, and fluids, and the subsequent impact of bacteria on the sperm architecture, activity, and fertilizing potential, has recently gained increased attention from the medical and scientific community. Current evidence strongly emphasizes the fact that the presence of bacteria in semen may have dire consequences on the resulting male fertility. Nevertheless, the molecular basis underlying bacteriospermia-associated suboptimal semen quality is sophisticated, multifactorial, and still needs further understanding. Bacterial adhesion and subsequent sperm agglutination and immobilization represent the most direct pathway of sperm-bacterial interactions. Furthermore, the release of bacterial toxins and leukocytic infiltration, associated with a massive outburst of reactive oxygen species, have been repeatedly associated with sperm dysfunction in bacteria-infested semen. This review serves as a summary of the present knowledge on bacteriospermia-associated male subfertility. Furthermore, we strived to outline the currently available methods for assessing bacterial profiles in semen and to outline the most promising strategies for the prevention and/or management of bacteriospermia in practice.

The Penis, the Vagina and HIV Risk: Key Differences (Aside from the Obvious)

Globally, most Human Immunodeficiency Virus type 1 (HIV) transmission occurs through vaginal–penile sex (heterosexual transmission). The local immune environment at the site of HIV exposure is an important determinant of whether exposure during sex will lead to productive infection, and the vaginal and penile immune milieus are each critically shaped by the local microbiome. However, there are key differences in the microbial drivers of inflammation and immune quiescence at these tissue sites. In both, a high abundance of anaerobic taxa (e.g., Prevotella) is associated with an increased local density of HIV target cells and an increased risk of acquiring HIV through sex. However, the taxa that have been associated to date with increased risk in the vagina and penis are not identical. Just as importantly, the microbiota associated with comparatively less inflammation and HIV risk—i.e., the optimal microbiota—are very different at the two sites. In the vagina, Lactobacillus spp. are immunoregulatory and may protect against HIV acquisition, whereas on the penis, “skin type” flora such as Corynebacterium are associated with reduced inflammation. Compared to its vaginal counterpart, much less is known about the dynamics of the penile microbiome, the ability of clinical interventions to alter the penile microbiome, or the impact of natural/induced microbiome alterations on penile immunology and HIV risk.

High-Risk HPV with Multiple Infections Promotes CYP2E1, Lipoperoxidation and Pro-Inflammatory Cytokines in Semen of Asymptomatic Infertile Men

High-risk human papillomavirus (HR-HPV) infection, followed by chronic inflammation and oxidative stress, is a major risk factor of male infertility. In this study, we explored the potential impact of high-risk (HR) HPV genotypes in single infection (SI) and multiple infections (MI) that promote CYP2E1 expression, oxidative damage and pro-inflammatory cytokines, possibly contributing to sperm damage and male infertility. Semen samples from 101 infertile military men were studied. We analyzed seminal parameters, namely, HPV genotyping, cytochrome P450 2E1 (CYP2E1), oxidative stress biomarkers (total antioxidant capacity (TAC), catalase (CAT) and superoxide dismutase (SOD)), lipid peroxidation (LPO), 8-hydroxiguanosine (8-OHdG) and pro-inflammatory cytokines (IFN-γ, IL-1β, IL-4, IL-6 and IL-8). Eighty-one men (80.2%, 81/101) were positive for HPV infection, and MI-HR-HPV was higher than SI-HR-HPV (63% vs. 37%). HPV-52 was the most frequently detected type (18.5%), followed by HPV-33 (11.1%), and the most frequent combination of genotypes detected was HPV-33,52 (11.1%), followed by HPV-18,31 (6.2%). The group with infected samples presented lower normal morphology and antioxidant levels compared to non-infected samples. In concordance, the infected group showed high levels of LPO, IFN-γ, IL-1β, IL-4 and IL-6 and downregulation of CAT and SOD enzymes. Interestingly, changes in motility B, low levels of TAC, overexpression of CYP2E1, LPO and IL-8 levels were higher in MI-HR-HPV than SI-HR-HPV, suggesting that HPV infection promotes a chronic inflammatory process and a toxic and oxidative microenvironment, which increases with MI-HPV infections.