Seminal elastase-inhibitor complex, a marker of genital tract inflammation, and negative IVF outcome measures: role for a silent inflammation?

Integrative Assessment of Seminal Plasma Biomarkers: A Narrative Review Bridging the Gap between Infertility Research and Clinical Practice

Infertility represents a significant global health challenge impacting millions of couples worldwide. Approximately half of all infertile couples exhibit compromised semen quality, indicative of diminished male fertility. While the diagnosis of male infertility traditionally relies on semen analysis, its limitations in providing a comprehensive assessment of male reproductive health have spurred efforts to identify novel biomarkers. Seminal plasma, a complex fluid containing proteins, lipids, and metabolites, has emerged as a rich source of such indicators. Reproduction depends heavily on seminal plasma, the primary transporter of chemicals from male reproductive glands. It provides a non-invasive sample for urogenital diagnostics and has demonstrated potential in the identification of biomarkers linked to illnesses of the male reproductive system. The abundance of seminal proteins has enabled a deeper understanding of their biological functions, origins, and differential expression in various conditions associated with male infertility, including azoospermia, asthenozoospermia, oligozoospermia, teratozoospermia, among others. The true prevalence of male infertility is understated due to the limitations of the current diagnostic techniques. This review critically evaluates the current landscape of seminal plasma biomarkers and their utility in assessing male infertility. Βy bridging the gap between research and clinical practice, the integrative assessment of seminal plasma biomarkers offers a multimodal approach to comprehensively evaluate male infertility.

A systematic review identifying seminal plasma biomarkers and their predictive ability on IVF and ICSI outcomes

The diverse nature and high molecule concentration of seminal plasma (SP) makes this fluid a good potential source for a potential biomarker that could predict assisted reproductive technology (ART) outcomes. Currently, semen quality parameters cannot accurately predict ART outcomes. A systematic literature search was conducted to identify human SP biomarkers with potential predictive ability for the outcomes of IVF and intracytoplasmic sperm injection. Observational cohort and case-control studies describing the association between biomarkers in human SP and the outcome of infertile men attending for ART were included. Forty-three studies were selected, reporting on 89 potential SP biomarkers (grouped as oxidative stress, proteins glycoproteins, metabolites, immune system components, metals and trace elements and nucleic acids). The present review supports 32 molecules in SP as potentially relevant biomarkers for predicting ART outcomes; 23 molecules were reported once and nine molecules were reported in more than one study; IL-18 and TGF-β1-IL-18 ratio were confirmed in distinct studies. This review presents the most comprehensive overview of relevant SP biomarkers to predict ART outcomes to date, which is of clinical interest for infertility investigations and assisted reproduction; nevertheless, its potential is under-exploited. This review could serve as starting point for designing an all-encompassing study for biomarkers in SP and their predictive ability for ART outcomes, and for developing a non-invasive diagnostic tool.

Effects of leukocyte elastase in semen on sperm quality

The study analyzed the effect of leukocyte elastase (LE) in 460 semen on sperm quality, and explore the reference interval of normal level of LE in semen. The differences of LE levels between normal semen and few, weak and abnormal semen were analyzed. Referring to domestic standards, the samples were divided into normal group (LE ≤ 250 ng/mL), occult infection (250 < LE ≤ 1000 ng/mL), and infection group (LE > 1000 ng/mL), and the differences in semen quality among the groups were compared. According to European standards, the samples were divided into normal group (≤600 ng/mL) and abnormal group (>600 ng/mL), and the differences in semen quality between the 2 groups were compared. The correlation between LE levels in semen and semen quality were analyzed. The positive rates of LE in the normal semen group and abnormal semen groups were 30.7% versus 34.7%, and there was no significant difference between the two groups (P > .05). When the semen divided into 3 groups, there was no significant difference between the physicochemical parameters, kinetic parameters, movement trajectory parameters, morphological parameters, and sperm DNA fragmentation index (DFI) (P > .05). There were significant differences in sperm morphology and sperm DFI between the two groups at 600 ng/mL (P < .05). Spearman correlation analysis showed that there was no significant difference between the level of LE in semen and physicochemical parameters, sperm kinetic parameters, sperm movement trajectory parameters, sperm morphological parameters, and sperm DFI (P > .05). It is appropriate to use 600 ng/mL as the threshold for the concentration of LE in semen; the correlation between the level of LE and sperm quality is not significant.

Leucocyte subpopulations in the seminal plasma and their effects on fertilisation rates in an IVF cycle

Controversy exists on the role of leucocytospermia on fertilisation rates and IVF outcomes. The aim of our study was to identify the effect of leucocytes and leucocyte subpopulations on fertilisation rates in an IVF cycle. A prospective comparative study of the leucocyte subpopulations of seminal fluid of partners of women attending an IVF cycle was conducted. The samples underwent immunocytochemical staining. The monoclonal antibodies used in this study include CD3, CD4, CD8 (T Cells), CD14 (monocytes/macrophages), CD16 (granulocytes), CD20 (B Cells), CD45 (Pan Leucocytes), CD56 (natural killer cells) and CD69 (activated T and B Cells). Of 21 patients who were recruited into the study, seven were identified as poor fertilisers (<35%) and 14 were identified as good fertilisers (>60%). Data were analysed with SPSS version 14. The total leucocyte counts (CD45) between the poor and good fertilisers were not statistically significant. The macrophages and the monocytes (CD14) were significantly elevated in the good fertilisers group in comparison with the poor fertilisers (P < 0.05). We also found that T cells (CD2, CD4, CD8) and CD14 (macrophages) correlated significantly (r = 0.47, P value < 0.01) with the fertilisation rate. Our study confirms that the presence of leucocytes does not adversely affect the fertilisation rates and the outcome of an IVF cycle. However, macrophages and the monocytes (CD14) were significantly elevated in the good fertilisers group. The increased phagocytic activity in these individuals might increase their fertilising potential by removing spermatozoa with abnormal morphology.

[Medical treatments and hygiene and dietary measures]

The causes of male infertility may be identified, with the possibility of drugs treatment, or they may be idiopathic, for which treatments are at the research stage. The treatments available aim to increase the quantity and quality of spermatozoa produced by increasing their fertilising capacity and protecting their nuclear structure. Hormone treatments - recombinant FSH, purified FSH - give different results depending on whether studies examine semen parameters or fertilisation and pregnancy rates. In the case of non-hormone treatments (folates, zinc, vitamins E or C, selenium, glutathione and carnitine), the data in the literature is also contradictory and there is no clear consensus of opinion. However, the studies make use of highly variable methodologies and many of them are non-randomised. In terms of hygiene and dietary measures, tobacco, alcohol and excess weight have a negative effect on semen parameters and it is relevant to encourage patients to adopt a healthier lifestyle.

Sperm quality and pregnancy rate after COX-2 inhibitor therapy of infertile males with abacterial leukocytospermia

BACKGROUND

Leukocytes are a frequent finding in seminal plasma of infertile males with abacterial inflammation. We evaluated the effects of treatment with rofecoxib, a cyclooxygenase-2 inhibitor, on sperm quality and pregnancy rate after intrauterine insemination (IUI) or monitored intercourse.

METHODS

We selected 47 infertile patients referred to our sterility centre for semen analysis. Sperm evaluation was performed by light microscopy with Papanicolau and eosin staining, before and 1 month after therapy. Swim-up selection was carried out in two steps. Starting 6-8 weeks after the end of therapy, couples underwent different procedures of assisted fertilization according to their semen parameters.

RESULTS

Semen analysis 30 days after the end of therapy showed a significant reduction in leukocyte concentrations with respect to baseline, an improvement of sperm motility and morphology, particularly the presence and shape of the acrosomal complex and tail structure. After monitored intercourse and IUI, pregnancy rate was 15.8 and 11.3%, respectively.

CONCLUSIONS

Our results suggest that a decrease in leukocytospermia after rofecoxib therapy was associated with recovery of all seminal characteristics in basal and swim-up selected samples. This general improvement could justify the positive outcome of ART after anti-inflammatory therapy.

Role of granulocyte elastase and interleukin-6 in the diagnosis of male genital tract inflammation

Chronic genital tract inflammations are a frequent cause or at least a concomitant factor of male fertility disturbances. The diagnosis is difficult because of the mostly asymptomatic course of the disease. Therefore, determination of biochemical markers of inflammation in addition to the number of leucocytes in the seminal plasma has been recommended. The aim of the study was to find out whether determination of granulocyte elastase and interleukin-6 provide comparable and reliable results with regard to diagnosis of genital tract inflammation; in addition, the association between genital tract inflammation and semen quality should be evaluated with special focus on potentially disturbed sperm functions like sperm motility and DNA integrity. In a prospective study, the concentrations of interleukin-6 (IL-6) and granulocyte elastase were determined in seminal plasma samples from 340 patients to investigate the relationship with other parameters of genital tract inflammation such as the number of peroxidase-positive cells and conventional semen parameters. Microbiological investigations were included. As post-testicular inflammatory influences may cause sperm DNA damage, the correlation between IL-6 and elastase and DNA integrity was evaluated by the sperm chromatin structure assay. IL-6 and elastase were significantly correlated both with each other (P < 0.01) and the number of peroxidase-positive cells (P < 0.01). IL-6 showed a highly significant negative correlation with sperm vitality (P < 0.01) and a significant negative correlation with sperm motility (P < 0.05). Elastase concentrations were highly significantly associated with the number of peroxidase-positive cells (P < 0.01) and negatively correlated with sperm vitality (P < 0.01). Moreover, there were significantly negative correlations with sperm motility (P < 0.05), progressive motility according to WHO a quality (P < 0.05) as well as sperm morphology (P < 0.05). In addition, a significant negative correlation was observed between elastase concentrations and percentage of spermatozoa with intact DNA, which may suggest the use of anti-inflammatory treatment. It can be concluded that both IL-6 and granulocyte elastase are useful and suitable as markers for silent genital tract inflammation; in contrast to previous contributions there were clear correlations of IL-6 and granulocyte elastase with sperm parameters, the relationship of elastase with semen quality being more marked. Moreover, the results of the study confirm the need for a change of the threshold value of peroxidase-positive cells according to WHO definition to lower levels for definition of silent genital tract inflammation.

[Sperm biochemical markers of genital tract inflammation: usefulness of elastase determination]

Genital tract inflammation was for a long time suspected of inducing sterility in the male. The role of leukocytes in sperm changes is still debated. The identification of inflammation is based on the presence of activated leukocytes and the elastase measurement. Residual inflammation is evaluated by the reactive oxygen species activity. The true damage caused by inflammation on spermatozoa is reflected in negative changes observed during sperm apoptosis. Increased sperm DNA fragmentation is frequently observed while classical sperm characteristics are not modified automatically. The diagnosis of genital tract inflammation, follow-up after treatment and prognosis in terms of fertility require the use of different and complementary parameters.