Detection of monocyte chemotactic and activating factor (MCAF) and interleukin (IL)-6 in human seminal plasma and effect of leukospermia on these cytokine levels

Immune regulatory cytokines in seminal plasma of healthy men: A scoping review and analysis of variance

OBJECTIVE

Seminal plasma cytokines are associated with fertility and reproductive health, but progressing their clinical utility is hampered by absence of reference data on concentration ranges of relevant cytokines in healthy men. We employed a systematic approach to assemble current evidence on the concentrations of immune regulatory cytokines present in seminal plasma (SP) of normozoospermic and/or fertile men and evaluated the impact of different platform methodologies for cytokine quantification.

EVIDENCE REVIEW

A systematic literature search was performed utilising PubMed, Web of Science and Scopus. Databases were searched from inception until 30th June 2022 inclusive, using combinations of keywords pertaining to seminal fluid and cytokines, and was restricted to human participants. Original data with values reported as concentration of specific cytokines in SP of men clearly defined as fertile or normozoospermic were extracted from studies written in English.

RESULTS

A total of 3769 publications were initially identified, of which 118 fulfilled the eligibility criteria for inclusion. A total of 51 individual cytokines are detectable in SP of healthy men. The number of studies reporting on each cytokine range from 1 to >20. The reported concentrations for many cytokines linked with fertility status, including IL6, CXCL8/IL8, and TNFA, are highly variable between published studies. This is associated with the different immunoassay methodologies utilised and may be exacerbated by a lack of validation of assays to ensure suitability for SP assessment. Due to the large variation between studies, accurate reference ranges for healthy men cannot be determined from the published data.

CONCLUSIONS

The concentrations of cytokines and chemokines detected in SP is inconsistent and highly variable between studies and cohorts, limiting current capacity to define reference ranges for cytokine concentrations in fertile men. The lack of standardisation in methods used to process and store SP, and variation in platforms used to evaluate cytokine abundance, are factors contributing to the observed heterogeneity. To progress the clinical utility of SP cytokine analysis will require standardisation and validation of methodologies so that reference ranges for healthy fertile men can be defined.

Critical Review: Immunomodulation by Seminal Factors and Implications for Male-to-Female HIV-1 Transmission

The role of semen in heterosexual transmission of the HIV-1 has been marginally viewed as an inert vehicle for the delivery of virus. However, studies from the field of reproductive biology have made it clear that seminal fluid is a complex and dynamic medium containing high concentrations of factors that play key roles in modulating the local immune response in the female reproductive tract during fertilization and embryogenesis. It is therefore strongly implied that the same seminal factors responsible for guiding the immune response in reproduction also play a role in male-to-female transmission of HIV-1. To begin to understand how these factors affect male-to-female HIV-1 transmission, multiple studies have comparatively profiled the contents of seminal fluid collected from uninfected and HIV-1-infected men. This review provides an overview of these studies, as well as a discussion of the potential impact of semen on HIV-1 transmission.

Characteristics and quantities of HIV host cells in human genital tract secretions

Human immunodeficiency virus (HIV)-infected leukocytes have been detected in genital secretions from HIV-infected men and women and may play an important role in the sexual transmission of HIV. However, they have been largely overlooked in studies on mechanisms of HIV transmission and in the design and testing of HIV vaccine and microbicide candidates. This article describes the characteristics and quantities of leukocytes in male and female genital secretions under various conditions and also reviews evidence for the involvement of HIV-infected cells in both horizontal and vertical cell-associated HIV transmission. Additional research is needed in this area to better target HIV prevention strategies.

Multiplex determination of murine seminal fluid cytokine profiles

Seminal fluid is known to be responsible for orchestrating mating-induced immunomodulation. Central to this process are numerous cytokines that modulate uterine leukocyte recruitment and trafficking. Despite this, a comprehensive analysis of the cytokine profile of murine seminal fluid is lacking. This study addressed this issue by using multiplex immunoassays to characterise the profile of interleukin (IL)-1α , IL-1β , IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12 (p40), IL-12 (p70), IL-13, IL-17, eotaxin, granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon (IFN)-γ, keratinocyte-derived chemokine (KC), monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α , MIP-1β , regulated upon activation normal T-cell expressed and secreted (RANTES), and tumour necrosis factor (TNF)-α in fluid drawn from the seminal vesicles of single mice (n= 18). Their levels and ratios were compared with those found in serum. IL-1α , IL-1β , IL-2, IL-5, IL-9, IL-12 (p40), IL-12 (p70), IL-13, IL-17, GM-CSF, IFN-γ, MCP-1 and TNF-α levels were significantly higher in serum; IL-4, G-CSF, eotaxin, KC and RANTES exhibited the opposite trend. Based on these findings, we propose a model of mating-induced immunomodulation that implicates seminal eotaxin, RANTES and MIP-1α in the relocation and concentration of extravasated migrating endometrial eosinophils to the luminal epithelium. Furthermore, KC may participate in uterine neutrophil chemotaxis and activation. Eotaxin and MIP-α , together with IL-1β and IL-9, may also enhance further cytokine synthesis for endometrial antigen-presenting cell recruitment for processing paternal ejaculate antigens. IL-4 and G-CSF could also minimise deleterious cell-mediated immunity and modulate IFN-γ production, thereby supporting the establishment of pregnancy.

Detection of erythropoietin in human seminal plasma

OBJECTIVE

To examine the presence of erythropoietin (EPO) in ejaculates and the association between EPO levels in seminal plasma and semen parameters.

DESIGN

Retrospective analysis.

SETTING

University hospital in Japan.

PATIENT(S)

Eighty-three infertile males and 16 volunteers with proven fertility.

INTERVENTION(S)

Semen was obtained by masturbation after 5 days of abstinence. Blood sample and split ejaculates of 16 volunteers with proven fertility were collected.

MAIN OUTCOME MEASURE(S)

Western blot analysis and enzyme-linked immunoassay in the seminal plasma and sperm parameters.

RESULT(S)

Western blot analysis showed that EPO protein was present in the seminal plasma. The EPO titers in the seminal plasma ranged from 1.5 mIU/mL to 45.0 mIU/mL by enzyme-linked immunoassay. There was no significant association between EPO levels and semen parameters. The first fraction of samples obtained by split ejaculation contained almost the same amount of EPO as the second fraction.

CONCLUSION(S)

Erythropoietin protein was constitutively present in seminal plasma. The seminal EPO originated from the prostate and seminal vesicle. No association between EPO levels in seminal plasma and sperm parameters was found in the present study.

Levels of interleukin-6 and interleukin-8 in seminal fluid of men attending an andrological clinic

The presence of interleukins (IL) and other cytokines in seminal plasma was demonstrated in the literature. In particular, the levels of IL-6 were found to be related to male accessory gland inflammation. The close correlation to leucocyte count indicates a production of interleukins from the leucocytes and by the prostate gland. No relation of IL-6 levels to spermatogenic activity was quoted in the literature. We measured IL-6 and IL-8 in 454 men and compared the values with seminal parameters. The mean values of IL-6 30.7 +/- 101.2 pg ml-1 and IL-8 2023 +/- 1721 pg ml-1. The correlation analysis revealed a significant correlation of IL-6 and/or IL-8 to age, total fructose, immunoglobulin G (IgG) concentration and leucocyte count. The significant correlation of IL-6 and fructose levels indicates that also the seminal vesicles take part in the production of seminal IL-6. No correlation of the two interleukins measured to sperm parameters occurred. The calculation of a single harmonic trend revealed a significant trend over the year of the levels of IL-6 with a maximum in December and a peak-to-trough variation of 33% of the mean. It may be the consequence of a higher frequency of seminal tract inflammations in autumn and winter.

Distinct expression pattern of cytokines in semen of men with genital infection and oligo-terato-asthenozoospermia

PROBLEM

The objective of this study was to evaluate the possible relevance of cytokines in seminal plasma (SP) of patients with accessory gland infection and oligoterato-asthenozoospermia.

METHOD OF STUDY

Semen samples were obtained by masturbation from 90 men and were examined for the presence of interleukin (IL)-2, IL-6, IL-8, IL-11 and soluble CD23 (sCD23) by enzyme-linked immunosorbent assay. Five groups were included: (1) fertile men (n = 20), (2) infertile men with varicocele and oligo-teratoasthenozoospermia (V-OTA, n = 20), (3) infertile men with genital infection and OTA (INF-OTA, n = 20), (4) infertile men with idiopathic testicular lesion and OTA (ITL-OTA, n = 20) and (5) infertile men with azoospermia (AZOO, n = 10).

RESULTS

We found that the mean level of IL-2 was higher in SP from infertile men compared with SP from fertile men (P < 0.05). Mean levels of IL-6, IL-8, IL-11 in SP of INF-OTA were higher than that of all other groups (P < 0.05, P < 0.05, P < 0.001, respectively). However, no significant differences could be detected between other groups. A significant increase was noted in sCD23 levels in SP from men with ITL-OTA compared with all other groups (P < 0.01). We have not observed any correlations between IL-2, IL-6, IL-8, IL-11 and sCD23 levels in SP and semen parameters. Spearman's correlation coefficient revealed that there was a significant association between IL-6, IL-8, IL-11 levels in men with INF-OTA.

CONCLUSION

The measurement of each cytokine separately in the SP of men with INF-OTA, in spite of the existing significant differences, does not have a diagnostic value in male infertility. However, a combined determination of IL-6, IL-8, IL-11 in the SP of men with genital infection and oligo-terato-asthenozoospermia may provide clinically useful information for the diagnosis of male accessory gland infection.

Detection of fractalkine in human seminal plasma and its role in infertile patients

BACKGROUND

Fractalkine is a relatively newly discovered CX(3)C chemokine, which is a chemoattractant for T cells, monocytes and natural killer cells. Several reports have demonstrated the association between chemokine levels in seminal plasma and semen quality. The fractalkine levels in ejaculates from normal donors and infertile male patients with or without asthenozoospermia, were examined and correlated with sperm motility and morphology.

METHODS AND RESULTS

Western blot analysis showed fractalkine protein to be present in the seminal plasma. Fractalkine titres in the seminal plasma of infertile men with asthenozoospermia (0.64 +/- 0.04 microg/ml; n = 58) were lower than those in patients without asthenozoospermia (0.94 +/- 0.10 microg/ml; n = 22, P < 0.01) and fertile donors (1.04 +/- 0.07 microg/ml; n = 10, P < 0.001). There was no significant difference between fractalkine levels in patients with and without leukospermia. No significant correlation was found between fractalkine and interleukin-8 levels in seminal plasma. Sperm motility was positively correlated (R(2) = 0.14, P < 0.001) with fractalkine concentration. The existence of CX(3)CR-positive leukocytes in semen was confirmed using specific primers for CX(3)CR.

CONCLUSIONS

These results suggest that fractalkine is a chemokine associated with sperm motility and the migration of CX(3)CR-positive leukocytes into semen.

The effect of RANTES on human sperm chemotaxis

BACKGROUND

Follicular fluid (FF) is a powerful stimulator of human sperm hyperactivation and the acrosome reaction. FF causes sperm accumulation by way of chemotaxis. The chemoattractant in FF has not yet been identified in the human. It is well known that some types of chemokine such as RANTES (Regulated on Activation Normal T Expressed and Secreted Chemokine) exist in genital tract fluids (for example, FF, seminal plasma and uterine fluid). Few reports appear to exist concerning the direct effect of chemokines on the function of human sperm.

METHODS

The chemotactic effect of RANTES on human sperm were investigated by capillary and double-chamber assays, while the chemokinetic effect was investigated using computer-assisted sperm analysis.

RESULTS

Both the capillary and double-chamber assays demonstrated a significant chemotactic effect of RANTES on human sperm. Anti-RANTES rabbit IgG partially neutralized the chemotactic effect of FF. In contrast, no statistically significant chemokinetic effect was observed in any motility parameter.

CONCLUSIONS

Here, it was demonstrated that mRNA for the RANTES receptors CCR-1 and CCR-5 are present in human sperm. Furthermore, RANTES is involved in the chemotactic effect of FF in vitro.

Elevated nitric oxide concentration in the seminal plasma of infertile males: nitric oxide inhibits sperm motility

PROBLEM

To evaluate the effect of nitric oxide in the seminal plasma on sperm motility.

METHOD

Seminal plasma concentrations of NO2-, a stable end product of nitric oxide, of 108 males of infertile couples and 15 proven fertile donors were measured and compared with spermatogram parameters. Motile sperm was incubated with a nitric oxide-generating drug, sodium nitroprusside, for 6 hr in the absence or presence of oxyhemoglobin, an inhibitor of nitric oxide.

RESULTS

The NO2- concentration in the seminal plasma was 6.58 +/- 0.5.6 microM in 26 infertile males with leukocytospermia, 5.51 +/- 0.25 microM in 82 infertile males without leukocytospermia, and 3.91 +/- 0.16 microM in 15 controls. There was a significant correlation between the NO2- concentration and sperm motility. Sodium nitroprusside reduced the sperm motility in a dose- and time-dependent manner and its reduction was completely inhibited by the addition of oxyhemoglobin.

CONCLUSION

These findings indicate that nitric oxide concentration in the seminal plasma of infertile males is elevated and that nitric oxide is an inhibitor of sperm motion.