Membrane Cholesterol Inhibits Progesterone-Mediated Sperm Function through the Possible Involvement of ABHD2.

Abhydrolase domain containing 2-acylglycerol lipase (ABHD2) was recently claimed as the membrane receptor of progesterone (P4) in sperm cells, mediating cell processes such as sperm chemotaxis and acrosome reaction. Here, we investigated the role of membrane cholesterol (Chol) on ABHD2-mediated human sperm chemotaxis. Human sperm cells were obtained from twelve normozoospemic healthy donors. ABHD2-Chol interaction was modelled by computational molecular-modelling (MM). Sperm membrane Chol content was depleted by incubating cells with cyclodextrin (CD) or augmented by the incubation with the complex between CD and Chol (CD:Chol). Cell Chol levels were quantified by liquid chromatography-mass spectrometry. Sperm migration upon P4 gradient was evaluated through the accumulation assay in a specific migration device. Motility parameters were evaluated by sperm class analyzer, whilst intracellular calcium concentration, acrosome reaction and mitochondrial membrane potential were evaluated with calcium orange, FITC-conjugated anti-CD46 antibody and JC-1 fluorescent probes, respectively. MM analysis showed the possible stable binding Chol to ABHD2, resulting in to major impact on the protein backbone flexibility. The treatment with CD was associated with a dose-dependent increase in sperm migration in a 160 nM P4 gradient, together with increase in sperm motility parameters and levels of acrosome reaction. The treatment with CD:Chol was associated with essentially opposite effects. Chol was, thus, suggested to inhibit P4-mediated sperm function through the possible inhibition of ABHD2.

Lipidomic Profile of Human Sperm Membrane Identifies a Clustering of Lipids Associated with Semen Quality and Function.

Reduced sperm motility and/or count are among the major causes of reduced fertility in men, and sperm membranes play an important role in the spermatogenesis and fertilization processes. However, the impact of sperm lipid composition on male fertility remains under-investigated. The aim of the present study was to perform a lipidomic analysis of human sperm membranes: we performed an untargeted analysis of membrane lipid composition in fertile (N = 33) and infertile subjects (N = 29). In parallel, we evaluated their serum lipid levels. Twenty-one lipids were identified by their mass/charge ratio and post-source decay spectra. Sulfogalactosylglycerolipid (SGG, seminolipid) was the most abundant lipid component in the membranes. In addition, we observed a significant proportion of PUFAs. Important differences have emerged between the fertile and infertile groups, leading to the identification of a lipid cluster that was associated with semen parameters. Among these, cholesterol sulfate, SGG, and PUFAs represented the most important predictors of semen quality. No association was found between the serum and sperm lipids. Dietary PUFAs and SGG have acknowledged antioxidant functions and could, therefore, represent sensitive markers of sperm quality and testicular function. Altogether, these results underline the important role of sperm membrane lipids, which act independently of serum lipids levels and may rather represent an independent marker of reproductive function.

Investigation of the Interaction between Human Serum Albumin and Branched Short-Chain Perfluoroalkyl Compounds.

The current trend dealing with the production of per- and polyfluoroalkyl substances (PFASs) involves the shifting toward branched short-chain fluorinated compounds known as new-generation PFASs. A key aspect to be clarified, to address the adverse health effects associated with the exposure to PFASs, is their binding mode to human serum albumin (hSA), the most abundant protein in plasma. In this study, we investigated the interaction between hSA and two representative branched short-chain PFASs, namely, HPFO-DA and C6O4. In-solution studies revealed that both compounds bind hSA with affinities and stoichiometries lower than that of the legacy long-chain perfluoroalkyl compound PFOA. Competition experiments using hSA-binding drugs with known site-selectivity revealed that both HPFO-DA and C6O4 bound to pockets located in subdomain IIIA. The crystal structure of hSA in complex with HPFO-DA unveiled the presence of two binding sites. The characterization and direct comparison of hSA interactions with new-generation PFASs may be key elements for the understanding of the toxicological impact of these compounds.

Proteolysis Targeting Chimeric Molecules: Tuning Molecular Strategies for a Clinically Sound Listening.

From seminal evidence in the early 2000s, the opportunity to drive the specific knockdown of a protein of interest (POI) through pharmacological entities called Proteolysis Targeting Chimeric molecules, or PROTACs, has become a possible therapeutic option with the involvement of these compounds in clinical trials for cancers and autoimmune diseases. The fulcrum of PROTACs pharmacodynamics is to favor the juxtaposition between an E3 ligase activity and the POI, followed by the ubiquitination of the latter and its degradation by the proteasome system. In the face of an apparently modular design of these drugs, being constituted by an E3 ligase binding moiety and a POI-binding moiety connected by a linker, the final structure of an efficient PROTAC degradation enhancer often goes beyond the molecular descriptors known to influence the biological activity, specificity, and pharmacokinetics, requiring a rational improvement through appropriate molecular strategies. Starting from the description of the basic principles underlying the activity of the PROTACs to the evaluation of the strategies for the improvement of pharmacodynamics and pharmacokinetics and rational design, this review examines the molecular elements that have been shown to be effective in allowing the evolution of these compounds from interesting proof of concepts to potential aids of clinical interest.

Structural Analysis of Human Serum Albumin in Complex with the Fibrate Drug Gemfibrozil.

Gemfibrozil (GEM) is an orally administered lipid-regulating fibrate derivative drug sold under the brand name Lopid®, among others. Since its approval in the early 80s, GEM has been largely applied to treat hypertriglyceridemia and other disorders of lipid metabolism. Though generally well tolerated, GEM can alter the distribution and the free, active concentration of some co-administered drugs, leading to adverse effects. Most of them appear to be related to the ability of GEM to bind with high affinity human serum albumin (HSA), the major drug-carrier protein in blood plasma. Here, we report the crystal structure of HSA in complex with GEM. Two binding sites have been identified, namely Sudlow's binding sites I (FA7) and II (FA3-FA4). A comparison of the crystal structure of HSA in complex with GEM with those of other previously described HSA-drug complexes enabled us to appreciate the analogies and differences in their respective binding modes. The elucidation of the molecular interaction between GEM and HSA might offer the basis for the development of novel GEM derivatives that can be safely and synergistically co-administered with other drugs, enabling augmented therapeutic efficacies.

E2F1 copy number variations in germline and breast cancer: a retrospective study of 222 Italian women.

BACKGROUND: Breast cancer is the most common neoplasia among women in developed countries. The risk factors of breast cancer can be distinguished in modifiable and unmodifiable factors and, among the latter, genetic factors play a key role. Copy number variations (CNVs) are genetic variants that are classified as rare when present in less than 1% of the healthy population. Since rare CNVs are often cause of diseases, over the last years, their contribution in carcinogenesis has become a relevant matter of study. E2F1 is a transcriptional factor that plays an important role in regulating cell cycle and apoptosis. Its double and conflicting role is the reason why it acts both as oncogene and as tumour suppressor, depending on cell context. Since anomalies in expression or in number of copies of E2F1 have been related to several cancers, we aimed to study number of germline copies of E2F1 in women with breast cancer in order to better elucidate their contribution as predisposing factor to this tumour. METHODS: We performed, hence, a retrospective study on 222 Italian women with breast cancer recruited from October 2002 to December 2007. TaqMan CNV assay and Real-Time PCR were carried out to analyse, respectively, E2F1 CNV and E2F1 expression in the subjects of the study. Chi square test or Fisher's exact test and Student's t-test were used to calculate the frequency of CNVs and differences in continuous variables between groups, respectively. RESULTS: Intriguingly, we found that 10/222 (4.5%) women with breast cancer had more copies than controls (0/200, 0%), furthermore, the number of copies positively correlated with E2F1 gene expression in breast cancer tissue, suggesting that the constitutive gain of the gene could translate into an increased risk of genomic instability. Additionally, we found that altered E2F1 copies were present prevalently in the patients with contralateral breast cancer (20%) and all of them had a positive family history, both typically associated with hereditary cancer. CONCLUSIONS: Our findings suggest that copy number variations of E2F1 might be a susceptibility factor for breast cancer, however, further studies on large cohorts are to be performed in order to better delineate the phenotype linked to the gain of E2F1 copies.

Hyaluronidase-based swim-up for semen selection in patients with human papillomavirus semen infection.

Infection by human papillomavirus (HPV) represents one of the most common sexually transmitted diseases in both men and women worldwide. Recently, the detection of HPV virions in the semen of a large percentage of sexually active men has been associated with detrimental effects on both sperm parameters and on assisted reproductive technologies (ART) treatment outcomes. Conventional semen washing procedure used in ART have proved to be ineffective in removing HPV bound to sperm, requiring the identification of more effective and specific methods. In the present study, we assessed the possible use of hyaluronidase for the detachment of HPV from sperm cell surface. Semen samples from five normozoospermic control subjects (CTRL) were incubated with HPV virus-like particles (HPV-VLP) and treated with hyaluronidase by both a modified swim-up procedure (M-SU) and single-cell approach (SCA). The treatment with hyaluronidase was associated with the complete loss of HPV-VLP signal on sperms by both M-SU and SCA. In addition, semen samples from 12 HPV-positive infertile patients were treated with hyaluronidase 80 IU/mL by M-SU, resulting in the complete loss of HPV-DNA signal from sperm surface. Finally, the possible impact of hyaluronidase treatment on sperm parameters was assessed on both sperms from the five CTRL subjects and on further five oligo-astheno-terato-zoospermic (OAT) patients, both HPV negative. The treatment with hyaluronidase was equally associated with a slight reduction of sperm viability and progressive motility in both CTRL and OAT. In conclusion, the treatment with hyaluronidase removed efficiently and safely HPV virions bound to spermatozoa.

Identification of Rare LRP5 Variants in a Cohort of Males with Impaired Bone Mass.

Osteoporosis is the most common bone disease characterized by reduced bone mass and increased bone fragility. Genetic contribution is one of the main causes of primary osteoporosis; therefore, both genders are affected by this skeletal disorder. Nonetheless, osteoporosis in men has received little attention, thus being underestimated and undertreated. The aim of this study was to identify novel genetic variants in a cohort of 128 males with idiopathic low bone mass using a next-generation sequencing (NGS) panel including genes whose mutations could result in reduced bone mineral density (BMD). Genetic analysis detected in eleven patients ten rare heterozygous variants within the LRP5 gene, which were categorized as VUS (variant of uncertain significance), likely pathogenic and benign variants according to American College of Medical Genetics and Genomics (ACMG) guidelines. Protein structural and Bayesian analysis performed on identified LRP5 variants pointed out p.R1036Q and p.R1135C as pathogenic, therefore suggesting the likely association of these two variants with the low bone mass phenotype. In conclusion, this study expands our understanding on the importance of a functional LRP5 protein in bone formation and highlights the necessity to sequence this gene in subjects with idiopathic low BMD.

Sperm Cholesterol Content Modifies Sperm Function and TRPV1-Mediated Sperm Migration.

Transient receptor potential channels-vanilloid receptor 1 (TRPV1) regulates thermotaxis in sperm-oriented motility. We investigated the role of membrane cholesterol (Chol) on TRPV1-mediated human sperm migration. Semen samples were obtained from five normozoospemic healthy volunteers. Sperm membrane Chol content, quantified by liquid chromatography-mass spectrometry, was modified by incubating cells with 2-hydroxypropyl-ß-cyclodextrin (CD) or the complex between CD and Chol (CD:Chol). The effect on sperm migration on a 10 µM capsaicin gradient (CPS), a TRPV1 agonist, was then investigated. Motility parameters were evaluated by Sperm Class Analyser. Intracellular calcium concentration and acrosome reaction were measured by staining with calcium orange and FITC-conjugated anti-CD46 antibody, respectively. TRPV1-Chol interaction was modelled by computational molecular-modelling (MM). CD and CD:Chol, respectively, reduced and increased membrane Chol content in a dose-dependent manner, resulting in a dose-dependent increase and reduction of sperm migration in a CPS gradient. MM confirmed a specific interaction of Chol with a TRPV1 domain that appeared precluded to the Chol epimer epicholesterol (Epi-Chol). Accordingly, CD:Epi-Chol was significantly less efficient than CD:Chol, in reducing sperm migration under CPS gradient. Chol inhibits TRPV1-mediated sperm function by directly interacting with a consensus sequence of the receptor.

Testosterone is sequestered in dysfunctional adipose tissue, modifying androgen-responsive genes.

BACKGROUND/OBJECTIVE: The recognized association between male hypogonadism and obesity has multifactorial implications on adipose tissue (AT) physiology. The fat solubility of testosterone (T) suggests a sequestration process in fat depots, leading to reduced circulating levels of T in obesity. Several evidence suggest that steroids play a two-sided inhibitory role on adipogenesis by locally decreasing lipid accumulation and by stimulating lipolysis. The current study investigates T trafficking and activity in dysfunctional AT. SUBJECTS/METHODS: Samples of subcutaneous AT (SAT) were obtained from explants from lipoaspirate plastic surgery in six obese and six normal weight male patients. Experimental procedures on both SAT explants and insulin-resistant (IR) 3T3-L1 adipocytes were performed, including real-time PCR and mass-spectrometry quantification. RESULTS: A significant deregulation of gene responsiveness to androgens in IR cells and obese SAT was observed (all p < 0.05), together with reduced T release after adrenergic stimulation (-10% compared with -55% in lean SAT, p = 0.021). Higher concentrations of intracellular T and estradiol in obese SAT were also observed (2.4 vs. 1.3 ng/g, p = 0.013 and 0.075 vs. 0.22 ng/g, p = 0.004, respectively). Testosterone accumulation resulted in even lower expression in androgen-responsive genes involved in lipolytic and anti-adipogenic pathways from both in vitro and ex vivo experiments. CONCLUSIONS: These results suggest an altered response of dysfunctional fat cells to testosterone stimulation, which normally favors lipolysis and induces an anti-adipogenic effect. The considerable reduction of lipolytic T release after adrenergic stimulation in obese SAT contributes to AT dysfunction, in a feedforward loop further reducing T levels in obese hypogonadal males.

Increased Cardiovascular Risk Associated with Chemical Sensitivity to Perfluoro-Octanoic Acid: Role of Impaired Platelet Aggregation.

Perfluoro-alkyl substances (PFAS), particularly perfluoro-octanoic acid (PFOA), are persisting environmental chemicals showing bioaccumulation in human tissues. Recently, exposure to PFAS has been associated with increased prevalence of cardiovascular diseases (CVDs). However, a causal role of PFAS in atherosclerosis pathogenesis is under-investigated. Here, we investigated the effect of PFOA exposure on platelets' function, a key player in atherosclerosis process. PFOA accumulation in platelets was evaluated by liquid chromatography-mass spectrometry. Changes in platelets' membrane fluidity and activation after dose-dependent exposure to PFOA were evaluated by merocyanine 540 (MC540) and anti P-Selectin immune staining at flow cytometry, respectively. Intracellular calcium trafficking was analyzed with Fluo4M probe, time-lapse live imaging. Platelets' aggregation state was also evaluated with Multiplate® aggregometry analyzer in 48 male subjects living in a specific area of the Veneto region with high PFAS environmental pollution, and compared with 30 low-exposure control subjects. Platelets' membrane was the major target of PFOA, whose dose-dependent accumulation was associated in turn with increased membrane fluidity, as expected by a computational model; increased activation at resting condition; and both calcium uptake and aggregation upon activation. Finally, exposed subjects had higher serum and platelets levels of PFOA, together with increased aggregation parameters at Multiplate®, compared with controls. These data help to explain the emerging association between PFAS exposure and CVD.

The rs2274911 polymorphism in GPRC6A gene is associated with insulin resistance in normal weight and obese subjects.

OBJECTIVE: Identification of the novel endocrine role of osteocalcin (OC) and its receptor GPRC6A has given rise to a new branch of research in OC/GPRC6A axis related to glucose metabolism. GPRC6A- and OC-deficient mice share features of the metabolic syndrome, in addition to male infertility. Recently, the polymorphism rs2274911 in GPRC6A was shown to be associated with testicular impairment. We aimed to investigate the role of rs2274911 polymorphism in glucose and lipid metabolism in a cohort of normal weight and obese subjects DESIGN, PATIENTS, SETTINGS: A total of 392 male and females, including 218 obese patients and 174 age-matched normal weight controls, were retrospectively selected. RESULTS: The distribution of rs2274911 alleles and genotypes did not differ either between normal weight and obese subjects or sexes (all P > 0·05). Age- and OC-adjusted multivariate analysis revealed that, in the normal weight group, fasting insulin and HOMA-IR increased in GA (P = 0·016 and P = 0·025) and AA genotypes (P = 0·033 and P = 0·040) compared with GG homozygotes. In the obese group, AA homozygotes had increased fasting glucose (P = 0·041 vs GG). Triglycerides, fasting insulin and HOMA-IR increased in both GA (P = 0·020, P < 0·001 and P = 0·001) and AA genotype (P = 0·021, P = 0·013 and P = 0·013). CONCLUSION: In a cohort of normal weight and obese subjects, we found that the nonrare polymorphism rs2274911 in the GPRC6A gene was associated with insulin resistance features, independently of the metabolic phenotype and OC levels.

Deregulation of sertoli and leydig cells function in patients with Klinefelter syndrome as evidenced by testis transcriptome analysis.

BACKGROUND: Klinefelter Syndrome (KS) is the most common abnormality of sex chromosomes (47,XXY) and represents the first genetic cause of male infertility. Mechanisms leading to KS testis degeneration are still not completely defined but considered to be mainly the result of germ cells loss. In order to unravel the molecular basis of global testis dysfunction in KS patients, we performed a transcriptome analysis on testis biopsies obtained from 6 azoospermic non-mosaic KS patients and 3 control subjects. RESULTS: The analysis found that, compared to controls, KS patients showed the differential up- and down-expression of 656 and 247 transcripts. The large majority of the deregulated transcripts were expressed by Sertoli cells (SCs) and Leydig cells (LCs). Functional analysis of the deregulated transcripts indicated changes of genes involved in cell death, inflammatory response, lipid metabolism, steroidogenesis, blood-testis-barrier formation and maintenance, as well as spermatogenesis failure. CONCLUSIONS: Taken together, present data highlight the modulation of hundreds of genes in the somatic components of KS patient testis. The increased LCs steroidogenic function together with the impairment of inflammatory pathways and BTB structure, result in increased apoptosis. These findings may represent a critical roadmap for therapeutic intervention and prevention of KS-related testis failure.

Role of zinc trafficking in male fertility: from germ to sperm.

STUDY QUESTION: What are the dynamics of zinc (Zn) trafficking in sperm, at the testicular, epididymal and ejaculate levels? SUMMARY ANSWER: Zn transporters are peculiarly expressed in the cells of the germ line and Zn uptake is maximal at the post-epididymal phase, where Zn is involved in the regulation of sperm functions. WHAT IS KNOWN ALREADY: Zn is known to influence several phases of sperm life, from germ cell development to spermiation. Zn trafficking across the membrane is allowed by specific families of transporters known as the ZnTs, which are involved in effluent release, and the Zips, which mediate uptake. STUDY DESIGN, SIZE, DURATION: We enrolled 10 normozoospermic healthy participants in an infertility survey programme, as well as 5 patients affected by testicular germ cell cancer, and 18 patients presenting with obstructive azoospermia, without mutations of the CFTR gene, and undergoing assisted reproductive technologies. PARTICIPANTS/MATERIALS, SETTING, METHODS: The research study was performed at our University Clinic. Semen samples, or biopsies or fine needle aspirates from the testis or epididymis, were obtained from each of the participants. Protein expression of main members of the ZnT and Zip families of Zn transporters was examined in human testis and epididymis samples by immunofluorescence. Quantification of sperm Zn content was performed by flow cytometry, atomic absorption spectrometry (AA) and autometallography. MAIN RESULTS AND THE ROLE OF CHANCE: Intratubular cells of the germ line displayed a high redundancy of Zip family members involved in Zn uptake, while ZnT transporters were more represented in epididymis. Testicular and epididymal spermatozoa contained less Zn than ejaculated spermatozoa (2.56 ± 0.51 and 12.58 ± 3.16 versus 40.48 ± 12.71 ng Zn/10(6)cells, respectively). Gain of hypermotility and acrosomal reaction were significantly linked to the loss of Zn content in ejaculated spermatozoa. LIMITATIONS, REASONS FOR CAUTION: This was an ancillary study performed on a small cohort of normozoospermic subjects. Although these results clarify the Zn trafficking during different phases of sperm life, no conclusive information can be drawn about the fertilizing potential of sperm, and the overall pregnancy outcomes, after Zn supplementation. WIDER IMPLICATIONS OF THE FINDINGS: Our data disclose the dynamics of Zn trafficking during over the sperm lifespan. STUDY FUNDING/COMPETING INTEREST(S): No external funding was sought or obtained for this study. No conflict of interest is declared.

Proteomics for the identification of peripheral markers in pituitary disease.

Although precision medicine moved its first steps from genomic medicine, it has gone far beyond genomics, considering the full complexity of cellular physiology. Therefore, the present time might be considered as the "post-genomic era." In detail, proteomics captures the overall protein profile of an analyzed sample. The goals of proteomic analysis are to perform a global analysis of protein expression and function, to systematically define the role proteins in physiological and pathological condition, to increase mechanistic understanding of the biological processes and to discover new biomarkers and therapeutic targets. In this narrative mini-review, the role of proteomics is discussed with a particular focus on the few attempts of the application of proteomic platforms for the identification of new biomarkers in pituitary diseases, namely in acromegaly, GH deficiency and male secondary hypogonadism.

Emerging Role of Eruca sativa Mill. in Male Reproductive Health.

A growing interest has been drawn to the use of traditional medicinal plants for the treatment of human diseases and, in particular, infertility and reproductive toxicity associated with environmental factors. The Mediterranean basin area is a recognized source of plant species with therapeutic interest. In this frame, Eruca sativa (ES) is an annual edible plant and a member of the Brassicaceae family. A relatively large number of studies, focusing on the biological effects of the extract from the leaves of ES on in vitro and in vivo models of disease, have been published in recent years. The present narrative review aims to analyze the phytochemical constituents, traditional uses, possible pharmacological activities, and recognized effects of ES on male reproductive outcomes. Available investigations have revealed the presence of a number of compounds with antioxidant properties, such as polyphenols, glucosinolates, flavonoids, and carotenoids in extracts from ES. Based on the chemical and pharmacological characteristics of the aforementioned compounds, we show that ES has possible preventive properties and therapeutic uses, especially in the functional derangements of the male reproductive system.

Emerging Role of Non-collagenous Bone Proteins as Osteokines in Extraosseous Tissues.

Bone is a unique tissue, composed of various types of cells embedded in a calcified extracellular matrix (ECM), whose dynamic structure consists of organic and inorganic compounds produced by bone cells. The main inorganic component is represented by hydroxyapatite, whilst the organic ECM is primarily made up of type I collagen and non-collagenous proteins. These proteins play an important role in bone homeostasis, calcium regulation, and maintenance of the hematopoietic niche. Recent advances in bone biology have highlighted the importance of specific bone proteins, named "osteokines", possessing endocrine functions and exerting effects on nonosseous tissues. Accordingly, osteokines have been found to act as growth factors, cell receptors, and adhesion molecules, thus modifying the view of bone from a static tissue fulfilling mobility to an endocrine organ itself. Since bone is involved in a paracrine and endocrine cross-talk with other tissues, a better understanding of bone secretome and the systemic roles of osteokines is expected to provide benefits in multiple topics: such as identification of novel biomarkers and the development of new therapeutic strategies. The present review discusses in detail the known osseous and extraosseous effects of these proteins and the possible respective clinical and therapeutic significance.

Genetic Causes of Qualitative Sperm Defects: A Narrative Review of Clinical Evidence.

Several genes are implicated in spermatogenesis and fertility regulation, and these genes are presently being analysed in clinical practice due to their involvement in male factor infertility (MFI). However, there are still few genetic analyses that are currently recommended for use in clinical practice. In this manuscript, we reviewed the genetic causes of qualitative sperm defects. We distinguished between alterations causing reduced sperm motility (asthenozoospermia) and alterations causing changes in the typical morphology of sperm (teratozoospermia). In detail, the genetic causes of reduced sperm motility may be found in the alteration of genes associated with sperm mitochondrial DNA, mitochondrial proteins, ion transport and channels, and flagellar proteins. On the other hand, the genetic causes of changes in typical sperm morphology are related to conditions with a strong genetic basis, such as macrozoospermia, globozoospermia, and acephalic spermatozoa syndrome. We tried to distinguish alterations approved for routine clinical application from those still unsupported by adequate clinical studies. The most important aspect of the study was related to the correct identification of subjects to be tested and the correct application of genetic tests based on clear clinical data. The correct application of available genetic tests in a scenario where reduced sperm motility and changes in sperm morphology have been observed enables the delivery of a defined diagnosis and plays an important role in clinical decision-making. Finally, clarifying the genetic causes of MFI might, in future, contribute to reducing the proportion of so-called idiopathic MFI, which might indeed be defined as a subtype of MFI whose cause has not yet been revealed.

Human papillomavirus proteins are found in peripheral blood and semen Cd20+ and Cd56+ cells during HPV-16 semen infection.

BACKGROUND: Human papillomavirus (HPV) currently represents an important risk factor for cancer development and infertility in humans. Whilst binding of HPV to spermatozoa has been associated with male infertility, an investigation about the presence of HPV-DNA in non-spermatozoal semen cells is lacking. Previous findings documented the presence of HPV in peripheral blood leukocytes. The aim of this study was to investigate the expression of HPV markers in semen and blood leukocytes during HPV-16 infection. METHODS: A total of 32 subjects, 16 patients affected by HPV-16 semen infection and 16 controls, were evaluated in our andrological centre and enrolled in the study. Semen non-spermatozoal cells from all subjects were isolated and evaluated for the expression of HPV-16 markers (DNA and L1, E6 proteins) and further characterized for their molecular phenotype. Analogue determination was performed on peripheral blood mononuclear cells. RESULTS: The presence of HPV-DNA by FISH analysis in a round cell population from semen, confirmed to be CD45+ leukocytes, was observed. These HPV-DNA containing-cells also displayed HPV-16-E6 and HPV-16-L1 viral proteins and, upon further investigation, were found to be CD20+ and CD56+, likely phenotypes of B cells and natural killer cells (NK) respectively. In 25% of the patient group, a very small population of peripheral blood mononuclear cells was found to be positive for HPV-DNA via FISH. These cells displayed the CD20+ and CD56+ phenotype alike. None of the control subjects displayed HPV-DNA in either semen or peripheral blood. CONCLUSION: Considering the role of CD20+ and CD56+ cell populations in the antiviral immune response, the detection of HPV markers on leukocytes may reflect the presence of virus particles within the endosomal compartment. However, the presence of HPV markers in circulating mononuclear cells raise concerns about the risk of developing cancers to distal organs.