Lipopolysaccharide Induces Interleukin-8 Production By Human Cervical Smooth Muscle Cells

Seminal plasma pro-inflammatory cytokines interferon-γ (IFNG) and C-X-C motif chemokine ligand 8 (CXCL8) fluctuate over time within men

STUDY QUESTION

Do seminal plasma pro-inflammatory cytokines interferon-γ (IFNG) and C-X-C motif chemokine ligand 8 (CXCL8) vary within individual men over time?

SUMMARY ANSWER

IFNG exhibits substantial variation that is independent of duration of abstinence but correlates with lipopolysaccharide (LPS) content, while CXCL8 varies moderately in association with duration of abstinence.

WHAT IS KNOWN ALREADY

Pro-inflammatory cytokines IFNG and CXCL8 in seminal fluid can adversely impact male and female fertility. Other cytokines as well as sperm parameters fluctuate considerably within individuals over time, but whether IFNG and CXCL8 vary similarly, and the determinants of variance, are unknown.

STUDY DESIGN, SIZE, DURATION

Between two and seven semen samples were collected from 14 proven fertile donors at 6-10 week intervals over the course of ~12 months, to assess variation over time in cytokines and LPS, and to investigate relationships with sperm parameters and possible regulatory factors.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The concentrations and total amounts per ejaculate of IFNG and CXCL8 were determined using commercial ELISA. Sperm parameters were assessed according to World Health Organization (WHO) IV standards and LPS was measured by limulus amebocyte lysate (LAL) assay. Mixed model analysis was utilized to determine the relative contribution of between- and within-individual factors in explaining variance. Relationships between cytokines, LPS and sperm parameters, as well as effect of age and duration of abstinence, were investigated by correlation analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Within-individual variability contributed to total variance particularly for both IFNG, CXCL8 and LPS, and was a stronger determinant than between-individual variability for IFNG and LPS. Normal sperm motility correlated inversely with CXCL8, and sperm concentration correlated inversely with LPS. Duration of abstinence was a determinant of total CXCL8, but not IFNG or LPS. Associations between LPS, IFNG and CXCL8 suggest IFNG and perhaps CXCL8 are influenced by microbial populations.

LIMITATIONS, REASONS FOR CAUTION

A limited number of donors from a single clinic were investigated. Clinical information on complete microbiology, BMI, nutrition, smoking and other lifestyle factors was unavailable. Further studies are required to determine whether the findings can be generalized to larger populations and different ethnicities.

WIDER IMPLICATIONS OF THE FINDINGS

These data reveal substantial variation over time in pro-inflammatory seminal fluid cytokines and imply existence of microbial or other environmental regulatory factors.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the National Health and Medical Research Council of Australia. The authors have no competing interests to disclose.

Spermatozoa and seminal plasma induce a greater inflammatory response in the ovine uterus at oestrus than dioestrus

Leukocyte infiltration and increased synthesis of cytokines in response to insemination is considered to enhance reproductive success. The present study investigated the inflammatory response to whole semen, spermatozoa and seminal plasma, with and without the addition of antibiotics, in the ovine uterus at oestrus and dioestrus. Seminal plasma and spermatozoa both contributed to increased IL-8 secretion (P < 0.01) by endometrial epithelial cells and a concurrent infiltration by neutrophils (P < 0.01). Increased GM-CSF secretion (P < 0.01) occurred in response to whole semen and spermatozoa when antibiotics were not used. Macrophages and eosinophils increased (P < 0.05) in the endometrial stroma when antibiotics were not used, and fewer mast cells were detected in the deep endometrial stroma after treatments containing antibiotics (P < 0.05). Neutrophil and IL-8 responses to insemination were greater at oestrus (P < 0.01) than at dioestrus and the GM-CSF response followed a similar trend. Eosinophil numbers were increased at oestrus (P < 0.01) but minimally affected by insemination. More macrophages were located in the superficial endometrial stroma at oestrus. These results indicate that spermatozoa, seminal plasma and possibly bacteria contribute to the post-insemination inflammatory response, and that leukocytes, GM-CSF and IL-8 secretion in the ovine uterus are influenced by ovarian hormones.

Innate and adaptive immunity in female genital tract: cellular responses and interactions

The mucosal immune system in the female reproductive tract (FRT) has evolved to meet the unique requirements of dealing with sexually transmitted bacterial and viral pathogens, allogeneic spermatozoa, and the immunologically distinct fetus. Analysis of the FRT indicates that the key cells of the innate and adaptive immune systems are present and functionally responsive to antigens. Acting through Toll-like receptors in the Fallopian tubes, uterus, cervix, and in the vagina, epithelial cells, macrophages, natural killer cells, and neutrophils confer protection through the production of chemokines and cytokines, which recruit and activate immune cells, as well as bactericidal and virucidal agents, which confer protection at times when adaptive immunity is downregulated by sex hormones to meet the constraints of procreation. The overall goal of this paper is to define the innate immune system in the FRT and, where possible, to define the regulatory influences that occur during the menstrual cycle that contribute to protection from and susceptibility to potential pathogens. By understanding the nature of this protection and the ways in which innate and adaptive immunity interact, these studies provide the opportunity to contribute to the foundation of information essential for ensuring reproductive health.