Seminal Plasma miRNAs Research Articles

Association between metabolic disorders and seminal plasma miRNA levels: a pilot study

BackgroundExcess weight and metabolic disorders have a negative impact on male reproductive functions. The mechanisms involved are numerous and complex and epigenetic mechanisms may also be involved, notably through the small non-coding RNAs. Among them, microRNAs (miRNAs) are of particular interest. This preliminary study aimed to identify the miRNAs differentially enriched in seminal plasma related to metabolic disorders and if some are also associated with spermatic parameters alterations. One hundred and sixty men between 18 to 45 years, partners of infertile couple, were included in this cohort. The miRNAs associated with metabolism were selected from the literature and assayed by quantitative real-time PCR using TaqMan gene expression assays. A subset of those with an interesting profile in seminal plasma were secondarily tested in blood.ResultsAmong the 11 selected miRNAs, seven were detected in seminal plasma (miR10b, miR19a, miR19b, miR34b, miR34c, miR133b, miRlet7c). A negative correlation was observed between seminal miR19a levels and metabolic syndrome, blood glucose and C-peptide. Seminal miR19b levels were also negatively correlated with metabolic syndrome. Seminal miR34c levels were negatively correlated with body mass index (BMI) and waist circumference. Seminal miR133b levels were positively correlated with BMI, waist circumference and leptin levels. Interestingly, modifications of miRNAs in seminal plasma seem specific since highlighted above correlations were not retrieved in the blood plasma for the miR19a, 19b, 10b, 34c.ConclusionFew metabolic and anthropometric disorders are correlated with the level of specific miRNAs in seminal plasma. Further studies will be required to decipher if other small non-coding RNAs may also be correlated with metabolic and anthropometric disorders and to assess their potential implication in the alteration of reproductive functions in men with obesity or metabolic disorders.Clinical studyMetabolic Syndrome and Male Infertility (Metasperme): Trial registration: NCT01974947. Registered 18 July 2013.

Differentially expressed miRNAs and potential therapeutic targets for asthenospermia.

Asthenozoospermia is detected in 40% of infertile men, and characterised by low sperm motility. MicroRNAs (miRNAs) play essential roles in spermatogenesis, but little is known regarding the function of seminal plasma miRNAs in asthenozoospermia. In this study, we collected seminal plasma samples from patients with asthenospermia and healthy men and employed high-throughput sequence technology to identify differentially expressed miRNAs. Thirteen altered miRNAs were confirmed by qRT-PCR. Six of these miRNAs were upregulated, and seven were downregulated. Five of the miRNAs (hsa-miR-34c-5p, hsa-miR-34b-5p, hsa-miR-146b-5p, hsa-miR-449a and has-miR-765) had been characterised previously, and eight of the others (miR-5000-3p, miR-4289, miR-6514-3p, miR-6882-5p and miR-6739-5p, miR-135a-5p, miR-509-3p and miR-196b-5p) were identified in asthenospermia for the first time in this study. These miRNAs were significantly associated with PI3K-Akt signaling pathway, MAPK signaling pathway, HIF-1 signaling pathway and FoxO signaling pathway. The identified dysregulated miRNA may be the key to the development of new and enhanced diagnosis and prognosis technologies for asthenospermia, and may also provide new therapeutic possibilities in the field of personalised medicine.

Correlation Between Protamine-2 and miRNA-122 in Sperm from Heroin-addicted Men: A Case-Control Study.

Recreational use of illicit drugs is one of the main factors affecting male fertility. However, the mechanisms of heroin smoke-associated damage to mature spermatozoa are still completely unknown. The aim of this study was to concomitantly examine the levels of protamine-2 gene and protein concentrations, the amount of miRNA-122 in seminal plasma and semen analysis findings in heroin-addicted men. In a case control study, twenty-four fertile men that lacked any recreational drug abuse were considered as the healthy group, and 24 addicted men who used only heroin for at least four months were selected as the addicted group. Semen samples were gathered by masturbation after 2 - 5 days of sexual abstinence. Following the preparation of a semen analysis by computer-assisted sperm analysis according to WHO (2010), the level of protamine-2 gene expression in sperm and miRNA-122 in seminal plasma was measured using real-time sqPCR. Also, protamine-2 protein concentrations were quantified by nuclear protein extraction, SDS-Page and western blotting. Among the studied variables, body mass index (27.75±0.88 vs. 22.30±0.36, p=0.001), seminal pH (7.79±0.06 vs. 7.58±0.06, p=0.003), white blood cell count in semen (1.69±0.41 vs. 8.61±1.73, p=0.001), motility (65.51±2.57 vs. 41.96±3.58, p=0.001) and survival rate (87.41±1.00 vs. 71.50±4.59, p=0.002) of sperm cells was significantly different between the healthy and addicted groups. In addition, the levels of protamine-2 gene and protein expression in the addicted group (0.05±0.02 and 0.10±0.02, respectively) were significantly lower than the healthy group (3.59±0.94 and 0.27±0.06, respectively) (p=0.002 and p=0.017, respectively). Seminal miRNA-122 levels in addicted men (3.51±0.73) were statistically higher than in healthy men (1.52±0.54) (p=0.034). However, there were some significant relationship between the studied parameters and addiction (p<0.05). This is one study on human infertility that evaluates the effects of heroin on protamine deficiency and seminal small RNAs expression levels. Heroin abuse may lead to male infertility by causing leukocytospermia, asthenozoospermia, protamine deficiency, and seminal plasma miRNA profile alteration.

Seminal plasma miRNAs in Klinefelter syndrome and in obstructive and non-obstructive azoospermia.

MicroRNAs are small, non-coding, single-strand oligonucleotides which regulate gene expression. There is little evidence in the literature about their role in azoospermia and no studies have investigated their presence in the seminal plasma of men with Klinefelter syndrome. This retrospective study investigated if there were any differences in microRNA expression (miR-509-5p, miR-122-5p, miR-34b-3p, miR-34c-5p) in the seminal plasma of patients with obstructive azoospermia, non-obstructive azoospermia and Klinefelter syndrome. Hormone levels were also investigated to identify any correlations with microRNA expression. We analysed 200 subjects (40 Klinefelter syndrome, 60 non-obstructive azoospermia with a normal karyotype, 60 obstructive azoospermia and 40 who were normozoospermic). All subjects underwent semen examination. Total RNA was obtained from seminal plasma and microRNA expression was analysed by RT-qPCR. There was a significant reduction in the expression of all investigated miRNAs in the seminal plasma of all patient categories in comparison with controls. There was a weak negative correlation between FSH values and miR-509-5p expression in non-obstructive azoospermic patients (r = -0.391; p = 0.014). We hypothesize that in non-obstructive azoospermia and Klinefelter syndrome patients, the downregulation of microRNAs may be caused by damage to the germ cells and aberrant spermatogenesis. In our opinion the identification of seminal plasma microRNAs deriving almost exclusively from the testes could be essential for the development of specific biomarkers for male infertility. The expression of such microRNAs, in combination with hormone values, could comprise testicular markers of abnormal spermatogenesis and failed mature sperm production.

Heterogenic Origin of Micro RNAs in Atlantic Salmon (Salmo salar) Seminal Plasma.

The origin and contribution of seminal plasma RNAs into the whole semen RNA repertoire are poorly known, frequently being overlooked or neglected. In this study, we used high-throughput sequencing and RT-qPCR to profile microRNA (miRNA) constituents in the whole semen, as well as in fractionated spermatozoa and seminal plasma of Atlantic salmon (Salmo salar). We found 85 differentially accumulated miRNAs between spermatozoa and the seminal plasma. We identified a number of seminal plasma-enriched and spermatozoa-enriched miRNAs. We localized the expression of some miRNAs in juvenile and mature testes. Two abundant miRNAs, miR-92a-3p and miR-202-5p, localized to both spermatogonia and somatic supporting cells in immature testis, and they were also highly abundant in somatic cells in mature testis. miR-15c-5p, miR-30d-5p, miR-93a-5p, and miR-730-5p were detected only in mature testis. miRs 92a-3p, 202-5p, 15c-5p, and 30d-5p were also detected in a juvenile ovary. The RT-qPCR experiment demonstrated lack of correlation in miRNA transcript levels in seminal plasma versus blood plasma. Our results indicate that salmon semen is rich in miRNAs, which are present in both spermatozoa and seminal plasma. Testicular-supporting somatic cells are likely the source of seminal plasma enrichment, whereas blood plasma is unlikely to contribute to the seminal plasma miRNA repertoire.

Expression of miRNA-371a-3p in seminal plasma and ejaculate is associated with sperm concentration.

The microRNAs of the miR-371-3 cluster are novel serum markers for testicular germ cell tumors. Sporadic reports suggested the expression of this miRNA in semen. To verify the expression of miR-371a-3p in seminal plasma and unprocessed ejaculate; to compare seminal plasma miRNA levels in germ cell tumors patients with those of controls; to look for an association of miRNA levels with semen quality. The miR-371a-3p expression was analyzed with qPCR. The study population consisted of 100 participants: seminal plasma samples from 20 germ cell tumors patients and 30 controls, serum samples from 12 healthy men, ejaculate samples from 38 men undergoing fertility testing. The seminal plasma miR-371a-3p levels of germ cell tumors patients were not different from controls. The miRNA expression was very low in serum but much higher in seminal plasma. In ejaculate samples, the miRNA expression significantly correlated with sperm concentration and the total sperm count. miR-371-a-3p is present in sperm-containing fluids. Seminal plasma levels cannot be used to distinguish germ cell tumors from controls. The correlation with sperm concentration in ejaculate samples suggests the spermatozoa as possible source of miR-371a-3p production. The miR-371a-3p levels in ejaculate could represent a novel biomarker for the non-invasive evaluation of male infertility.

Altered microRNAs expression levels of sperm and seminal plasma in patients with infertile ejaculates compared with normozoospermic males

Approximately 15% of couples are unable to conceive after one year of unprotected intercourse. Because sperm can be accessed with ease, it is reasonable to search for non-invasive biomarkers in semen. MicroRNAs are a family of short single-stranded non-coding RNA molecules that are capable of regulating gene expression and causing mRNA degradation. We studied the most common 11 spermatogenesis-related microRNAs expression levels in sperm and seminal plasma from patients with oligozoospermic or asthenozoospermic ejaculates, and in men with normozoospermic ejaculates. Five of these miRNAs were significantly upregulated and three were downregulated in infertile males compared to men with normozoospermic ejaculates. A statistically significant negative correlation was found between the sperm concentration and several microRNA expression level (let-7a, miR-7-1-3p, miR-141, miR-200a, and miR-429, p < 0.0001) both in sperm and in seminal plasma. We also found positive correlation between sperm concentration and some miRNA expression levels (miR-15b, miR-34b, and miR-122, p < 0.001) in sperm and in seminal plasma. This is the first study to demonstrate differences between sperm and seminal plasma miRNA expression level and to identify a correlation between the sperm concentration and miRNAs expression level. Therefore, these MiRNAs could have the potential be used as non-invasive biomarkers to diagnose males with impaired sperm production.

Cytological and molecular aspects of the ageing sperm.

Is ageing associated with a decline in semen quality and molecular changes to human sperm? Semen quality declines with advancing age and characteristic molecular changes take place during the ageing process, including increased sperm DNA damage, altered sperm protamination and altered seminal plasma miRNA profile. During ageing, the reproductive system is exposed to physiological changes and potentially damaging factors that may impair testicular function. Reactive oxygen species (ROS) can induce errors during DNA replication, transcription or post-transcriptional events (fragmentation, chromatin condensation abnormalities and protamine expression defects). Semen parameters from 2626 healthy men aged 20-81 years were evaluated retrospectively from those attending our University Laboratory between 2011 and 2016 for andrological screening or as part of an andrological work-up. Subjects were divided into six groups by age (20-32, 33-37, 38-40, 41-44, 45-50, 51-81 years). From these subjects, semen samples from 40 elderly men (50-81 years) and 40 young men (20-40 years) (control group), all non-smokers of normal weight, were selected for the evaluation of sperm chromatin integrity, PRM1, PRM2, TNP1 and TNP2 gene expression, and microRNA expression profile in seminal plasma. Semen was analysed according to WHO 2010. Sperm DNA fragmentation (SDF) was evaluated using TUNEL assay; sperm PRM1, PRM2, TNP1 and TNP2 gene expression was evaluated by quantitative RT-PCR amplification; miRNA expression profiles were analysed by TaqMan Array Cards and validated by RT-PCR amplification. Cytological analysis - Semen volume, progressive motility and number of progressively motile sperm were significantly lower in elderly than in younger subjects (sextiles 51-81 versus 20-32 years; P < 0.001), while the percentage of abnormal forms in these subjects was significantly higher than in the 20-32 age group (P = 0.002). Binomial logistic regression models revealed an association between age and semen parameters: age 51-81 was associated with changes in total sperm number (OR 2.47; 95% CI 1.52-4.02; P < 0.001), progressive motility (OR 3.63; 95% CI 2.49-5.30; P < 0.001), and abnormal forms (OR 3.89; 95% CI 2.71-7.26; P < 0.001). Obesity was associated with reduced progressive motility (OR 1.58; 95% CI 1.14-2.19; P = 0.006) and an increase in abnormal forms (OR 1.87; 95% CI 1.02-3.57; P = 0.021). In contrast, smoking did not contribute significantly to changes in semen parameters. Molecular analysis - Elderly men showed a significantly higher percentage of SDF (23.1 ± 8.7 versus 9.8 ± 2.6%; P < 0.001) and a significantly lower expression of PRM1 (mean fold change 2.2; P = 0.016) and PRM2 (mean fold change 4.6; P < 0.001), compared to younger controls. Furthermore, miR-146a showed a 3-fold lower expression (P < 0.001), miR-371 a 14-fold lower expression (P < 0.001), and miR-122 a 5-fold lower expression (P = 0.01) in the elderly men. While typical chronic age-related conditions (cardiovascular, respiratory diseases) were excluded, the presence of subclinical underlying diseases cannot be excluded in the elderly population. Subjects referred to our clinic might not be fully representative of the general population. Although a careful medical history and physical examination excluded most andrological conditions that might affect spermatogenesis, we cannot exclude the presence of possible asymptomatic or idiopathic conditions. Furthermore, TUNEL, in common with other SDF detection methods (with the exception of the alkaline comet assay), does not distinguish between single and double strand breaks. The role of obesity suggests that conditions related to lifestyle factors may further worsen age-related sperm parameter impairment. Increased SDF and altered protamine expression suggest the genomic fragility of sperm in advanced age. Changes in the miRNA expression pattern with age could contribute to the identification of a characteristic molecular signature of the ageing process, a potential new biomarker for male reproductive function during the physiological ageing process. This work was supported by a grant from the Italian Ministry of Education and Research (MIUR-PRIN 2015- 2015XSNA83-002) and 'Sapienza' University of Rome Faculty of Medicine. The authors have no conflicts of interest. N/A.

Patterns of expression of sperm and seminal plasma microRNAs in boar semen

Although sperm and seminal plasma differ in their origin, biophysical and biochemical properties of seminal plasma influence the sperm function. Seminal plasma is a fluid medium containing substances from testes, epididymides and accessory glands. Composition of seminal plasma varies among animal species and in boars, prostate and bulbourethral glands are major contributors to the volume and contents. While the origin of some components of seminal plasma are known, the source of recently discovered seminal plasma microRNAs remains unknown, in part due to the difficulty of recovering and characterizing RNA from porcine sperm and seminal plasma. To test the hypothesis that seminal plasma miRNAs interact with sperm, the first objective was to validate protocols for recovering RNAs from porcine seminal plasma and sperm, whereas the second objective was to characterize expression patterns of 84 prioritized microRNAs employing real time PCR methodology. The study identified a relationship between sperm and seminal plasma microRNAs, based on the normalized threshold cycle of amplifying cDNA in sperm and seminal plasma from the same semen of Landrace boars. Therefore, it was concluded that seminal plasma miRNAs may originate from sperm or these miRNAs may shuttle between sperm and seminal plasma in order to facilitate cell-to-cell communication.

Down-regulated let-7b-5p represses glycolysis metabolism by targeting AURKB in asthenozoospermia

Glycolysis, through anaerobic respiration, can supply energy for human sperm motility. MicroRNAs (miRNAs) could participate in the glycolytic pathway through regulating target genes. To investigate the potential role of glycolysis-related miRNAs in asthenozoospermia, TaqMan Low Density Array (TLDA) was used to screen potentially functional miRNAs, and seven glycolysis-related miRNAs were isolated to be related to asthenozoospermia. After qRT-PCR validation, only one seminal plasma miRNA, let-7b-5p, was found significantly decreased in severe asthenozoospermia cases compared with healthy controls. To further understand whether let-7b-5p is involved in asthenozoospermia by regulating the glycolytic pathway, we carried out gain-and-loss function study of let-7b-5p in GC-2 cells and detected the glycolytic activities. Our results showed that knocking down let-7b-5p could inhibit glycolytic activities. Besides, we also found overexpressed Aurkb (a target gene of let-7b-5p) could recapitulate the effects of knocking down let-7b-5p. Our findings indicated that low expression of let-7b-5p could repress glycolysis in asthenozoospermia by targeting AURKB.

Role of microRNAs in spermatogenesis

Male germ cells have a complex transcriptome. In addition to proteincoding messenger RNAs, many noncoding RNAs, including microRNAs (miRNAs), are produced. The miRNAs are important regulators of gene expression. They function mainly post-transcriptionally to control the stability or translation of their target messenger RNAs. The miRNAs are expressed in a cell-specific manner during spermatogenesis to participate in the control of each stage of male germ cell differentiation. Clinical studies have exploited the well-defined expression profiles of miRNAs, and human spermatozoal or seminal plasma miRNAs have been explored as potential biomarkers for male factor infertility.

Mitochondria-related miR-151a-5p reduces cellular ATP production by targeting CYTB in asthenozoospermia.

Mitochondria, acting as the energy metabolism factory, participate in many key biological processes, including the maintenance of sperm viability. Mitochondria-related microRNA (miRNA), encoded by nuclear genome or mitochondrial genome, may play an important regulatory role in the control of mitochondrial function. To investigate the potential role of mitochondria-related miRNAs in asthenozoospermia, we adopted a strategy consisting of initial screening by TaqMan Low Density Array (TLDA) and further validation with quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Validation of the profiling results was conducted in two independent phases. Eventually, two seminal plasma miRNAs (sp-miRs) (miR-101-3p, let-7b-5p) were found to be significantly decreased, while sp-miR-151a-5p was significantly increased in severe asthenozoospermia cases compared with healthy controls. To further study their potential roles in asthenozoospermia, we then evaluated mitochondrial function of GC-2 cells transfected with these potentially functional miRNAs. Our results demonstrated that transfection with miR-151a-5p mimics decreased the mitochondrial respiratory activity. Besides, Adenosine Triphosphate (ATP) level was decreased when transfected with miR-151a-5p mimics. In addition, Cytochrome b (Cytb) mRNA and protein levels were also decreased when miR-151a-5p was overexpressed. These results indicate that miR-151a-5p may participate in the regulation of cellular respiration and ATP production through targeting Cytb.

Genome-wide microRNA expression profiling in idiopathic non-obstructive azoospermia: significant up-regulation of miR-141, miR-429 and miR-7-1-3p

What is the profile of miRNAs in seminal plasma of patients with non-obstructive azoospermia (NOA)? miR-141, miR-429 and miR-7-1-3p are significantly increased in seminal plasma of patients with NOA compared with fertile controls. There is currently an urgent need to develop a noninvasive diagnostic test for NOA. Altered microRNA (miRNA) profiles have been proposed as potential biomarkers for the diagnosis of disease states. A total of 200 subjects (n = 100 for NOA, n = 100 for fertile control) were recruited to participate in this study. Recruitment took place from May 2008 to June 2010. We employed a strategy consisting of initial screening by TaqMan Low Density Array then further validation with a TaqMan quantitative RT-PCR assay. Validation of the profiling results was conducted in two independent phases. In addition, the expression of the three validated seminal plasma miRNAs (sp-miRNAs) was examined in testicular tissues of patients with NOA and of fertile controls. Methylation status and functional analyses were also performed for the identified sp-miRNAs. miR-141, miR-429 and miR-7-1-3p were significantly increased in seminal plasma of patients with NOA compared with fertile controls. As sensitive and specific biomarkers, the profiling of these three identified sp-miRNAs provides a novel noninvasive, semen-based test for NOA diagnosis. The methylation status of these sp-miRNAs was inversely associated with their expression patterns. Additionally, we found that Cbl and Tgfβ2 were down-regulated by miR-141, while Rb1 and Pik3r3 were down-regulated by miR-7-1-3p. miRNA expression profile was investigated in seminal plasma samples from only a small number of NOA patients. In future investigations, a larger sample size should be adopted and the functional role of the three sp-miRNAs should be further characterized in animal models. Given that sp-miRNAs show reproducible and stable expression levels, they are potentially novel noninvasive biomarkers for the diagnosis of NOA. We propose that the three sp-miRNAs described above may participate in a methylation-miRNA-gene network related to NOA development. This work provides a foundation for interpretation of miRNA changes associated with pathogenesis of NOA and extends the current understanding of human NOA pathogenesis.

Seminal plasma microRNAs: potential biomarkers for spermatogenesis status

MicroRNAs (miRNAs) are small non-coding RNAs (18-25 nt), playing important regulatory roles via interaction with cellular messenger RNAs. The altered expression of miRNAs in specific tissues has been associated with diseases such as cancer and diabetes. We examined the presence of two selected miRNAs (miR-19b and let-7a) in human seminal plasma from fertile men and idiopathic infertile patients with oligozoospermia and non-obstructive azoospermia (NOA) using quantitative real-time PCR. We detected miRNAs in the seminal plasma of humans. The levels of miRNAs in the seminal plasma were reproducible in repeat samples from the same individuals. In addition, we examined the expression patterns of two selected miRNAs in 96 idiopathic infertile males (48 oligozoospermia and 48 NOA) and 48 fertile controls. Another 48 individuals of each group were used for verification. Our data showed that the expression levels of these two miRNAs in the seminal plasma significantly increased in idiopathic infertile males with NOA compared with fertile controls, whereas the expression levels were similar between idiopathic infertile males with oligozoospermia and fertile controls. In conclusion our results indicate that the expression of miR-19b and let-7a in the seminal plasma are reproducible and stable. Aberrant over-expression levels of miR-19b and let-7a may be an indicator of spermatogenic failure.

Altered Profile of Seminal Plasma MicroRNAs in the Molecular Diagnosis of Male Infertility

Although microRNAs (miRNAs) play essential roles in spermatogenesis, little is known about seminal plasma miRNAs in infertile men. We investigated the profile of seminal plasma miRNAs in infertile men to identify miRNAs that are altered in infertility; we then evaluated their diagnostic value. Seminal plasma samples were obtained from 289 infertile men and 168 age-matched fertile control individuals. The stability of the miRNAs was first assessed by time-course and freeze-thaw cycle analyses. The Solexa sequencing technology was used for an initial screen of the miRNAs in samples pooled from 45 patients with nonobstructive azoospermia, 58 patients with asthenozoospermia, and 100 fertile controls. A stem-loop quantitative reverse-transcription PCR (RT-qPCR) assay was conducted in the training and verification sets to confirm the concentrations of the altered miRNAs in 73 patients with nonobstructive azoospermia, 79 patients with asthenozoospermia, 34 patients with oligospermia, and 68 fertile controls. The miRNAs in seminal plasma were stable. The Solexa sequencing analysis demonstrated 19 markedly altered miRNAs in the patient groups, compared with the control group. RT-qPCR analysis identified 7 miRNAs (miR-34c-5p, miR-122, miR-146b-5p, miR-181a, miR-374b, miR-509-5p, and miR-513a-5p) as markedly decreased in azoospermia but increased in asthenozoospermia. The area under the ROC curve for these miRNAs ranged from 0.733 to 0.921, markedly higher than for routine biochemical parameters (0.510-0.622). Moreover, the concentrations of some selected miRNAs were also increased in the semen sperm of the asthenozoospermia patients. The measurement of miRNAs in seminal plasma provides a novel, noninvasive approach for diagnosing male infertility.