Effect of boar seminal plasma and seminal vesicle fluid on porcine lymphocytes

Cytokine expression in the gilt oviduct: effects of seminal plasma, spermatozoa and extender after insemination

Effects of semen components [fresh semen in extender, spermatozoa in extender (Spz), seminal plasma (SP)], or extender alone (Beltsville thawing solution, BTS) on the expression of selected cytokines [interleukin (IL)-1beta, IL-6, IL-10 and transforming growth factor (TGF)-beta1)] as well as the presence of cells positive for CD8 or CD25 were studied in the pig oviduct. In addition, cytokines in SP and oviductal flushings were analyzed. In experiment (Exp) I, groups of gilts were sampled at 5-6h after insemination with SP, Spz, fresh semen in BTS or only BTS (control). In Exp II, gilts were sampled 35-40 h after insemination with SP, Spz, BTS or only catheter insertion (control). Most oviductal flushing samples were positive (> or =detectable limits) for IL-10 and TGF-beta1 but only few for IL-6. The IHC-labelling of IL-6, IL-10 and TGF-beta1 was evident, especially in the epithelial cells of the isthmus and infundibulum as well as in the cells of the regional (mesometrial) lymph node. Cilia of the epithelium were positive for IL-6 (strongest in the infundibulum) and TGF-beta1 (strongest in the isthmus) but negative for IL-10. There were no consistent differences in IHC-labelling of the cytokines in relation to different treatments, except at 35-40 h after insemination (Exp II), when IL-6 was slightly higher in epithelium of the SP group and IL-10 in the infundibular connective tissue was higher in the SP and Spz groups. In the isthmus and infundibulum, there were no differences between animals inseminated with BTS (control) and the semen components for any of the cytokine mRNAs at 5-6h after insemination (Exp I). However, later (35-40 h, Exp II), insemination with SP, Spz and BTS alone appeared to up-regulate TGF-beta1 mRNA expression compared with the control group (without any fluid infused). In all treatment groups, the mRNA level for TGF-beta1 was higher than for IL-1beta, IL-6 and IL-10. Higher mRNA levels of all cytokines were found in the isthmus compared with the infundibulum. Numbers of CD8-positive cells (both in epithelium and connective tissue) appeared higher in the infundibulum compared with the isthmus and were mostly higher shortly (Exp I) after treatment with SP, SPZ and BTS than later (Exp II) in both segments. CD25-positive cells were few and found solely in the sub-epithelial connective tissue. The results indicate that in the porcine oviduct, IL-6, IL-10 and TGF-beta1 are endogenous produced and that TGF-beta1 may have a more important role for immunomodulation than the other cytokines, especially in isthmus. Differences between isthmus and infundibulum in cytokine mRNA expression and in presence of CD8-positive cells indicate different patterns of immune reactivity in the upper and lower parts of the oviduct.

Purified porcine seminal plasma protein enhances in vitro immune activities of porcine peripheral lymphocytes

The porcine seminal plasma protein (PSP) accounts for much more than 50% of the total proteins in seminal plasma. PSP has been previously purified and its biochemical properties characterized. However, the biological functions of PSP remain to be elucidated. We hypothesize that PSP is involved in the regulation of uterine immune activity. In the current study, effects of PSP on in vitro lymphocyte activities and the presence of PSP binding sites on lymphocytes were examined. In mitogen-induced proliferation assay, lymphocytes from peripheral blood of gilts were cultured with pokeweed mitogen (PWM), phytohemagglutinin (PHA), or concanavalin A (Con A) in the presence or absence of PSP. PSP at 50, 125, and 250 ng/well augmented PWM-induced [3H]thymidine uptake in a dose-responsive manner by 152.8 +/- 8.1%, 225.9 +/- 35.2%, and 274.8 +/- 53.6%, respectively, compared with that of control. PSP did not alter lymphocyte proliferation in the absence of PWM. Similarly, PSP had little or no effect on PHA- or Con A-induced lymphocyte proliferation. In one-way mixed lymphocyte reactions, PSP at 50, 125, and 250 ng/well enhanced [3H]thymidine uptake in a dose-responsive manner by 181.5 +/- 16.5%, 339.9 +/- 48.2%, and 600.1 +/- 84.8% of control, respectively. Using biotinylated PSP-I, PSP binding sites were localized on approximately 3-5% of the lymphocyte population. In summary, we have demonstrated that PSP itself is not a mitogen/antigen to porcine lymphocytes but that it has a stimulatory effect on lymphocyte activities initiated by PWM or surface antigens of lymphocytes. PSP may exert its functions by interacting with PSP binding sites on a subpopulation of porcine lymphocytes. The high potency of PSP on lymphocyte activities and the abundance of PSP in seminal plasma have suggested that PSP may play an important role in regulating immune responses in the porcine uterine environment.

Inflammatory response in the pig uterus induced by seminal plasma

The immunological and physiological influence of seminal plasma on the local uterine environment was investigated by immunohistochemical and flow cytometrical studies on uterine tissues and lymph nodes taken from gilts after mating with a vasectomised boar and from control, unmated gilts. These studies revealed that mating with a vasectomised boar induces an acute transient inflammatory response in the endometrium resulting in marked changes in the presence and distribution of leukocytes and extensive proliferation of the endometrial glands. At the same time there was an increase in CD8L and sIg+ cells and an up-regulation of MHC class II and IL-2 receptor expression in the uterine lymph nodes of mated pigs. This would suggest that seminal plasma deposited in the uterus can activate cells in the local draining lymph nodes. Together, these results demonstrate in utero that pronounced immunological and physiological changes are induced in vivo by seminal plasma.

Binding characteristics and immunolocalization of porcine seminal protein, PSP-I

PSP-I, a 13 kDa protein purified from boar seminal plasma, was found to have about 50% amino acid sequence homology with a family of zona pellucida-binding proteins known as spermadhesins. These proteins are produced by the accessory gland(s) of the male reproductive tract and coat the spermatozoa during ejaculation. In this study, we have investigated the possible biological functions of PSP-I using a solid-phase protein binding assay and its site of synthesis using both Western blot and immunocytochemical analyses. PSP-I was found to bind a number of proteins including endo-beta-galactosidase digested ZP3, soybean trypsin inhibitor, IgA, IgG and alpha-casein, indicating that it may have multiple functions. The protein or carbohydrate structures were not critical in the binding, since polyvinyl sulfate could effectively inhibit the binding of PSP-I to these proteins. Western blot analysis using specific antiserum to PSP-I showed that the protein was present in the seminal vesicle but not in the testes, epididymis or prostate. The protein was revealed by immunocytochemical analysis in the epithelium of seminal vesicles but not in the testes or the epididymis. It is concluded that PSP-I is synthesized by the epithelium of the seminal vesicles, secreted into the semen during ejaculation, and may be involved in various reproductive functions, such as preventing premature acrosome reaction and immunosuppression.

Biological functions of the water-insoluble fraction of mouse seminal vesicle fluid. I. Suppression of the blastogenic response of lymphocytes

The effects of the water-insoluble fraction of mouse seminal vesicle fluid (WIF-SVF) on lymphocytes was investigated to clarify its role in reproductive immunity. WIF-SVF inhibited the blastogenic response of T-cells to concanavalin-A (Con-A), but it did not inhibit the blastogenic response of B-cells to lipopolysaccharide (LPS). Pretreatment of splenocytes with WIF-SVF did not suppress the blastogenic response of splenocytes to Con-A when treated cells were washed prior to culture. WIF-SVF did not inhibit the proliferation of Con-A activated splenocytes, the response of listeria-immune splenocytes to listerial antigen, or the proliferation of IL 2-dependent HT-2 cells, or the growth of tumour cells (Yac 1 cells, Ehrlich ascites carcinoma cells, EL-4 cells). A listerial antigen-specific immune response was not induced after mice were immunized with both listerial antigen and WIF-SVF. WIF-SVF is mainly composed of protein and its suppressive activity was enhanced by heating at 100 degrees C. These results suggest that WIF-SVF inhibits the responsiveness of T-cells to antigens or mitogens non-specifically at the initial stage.

Biological functions of mouse seminal vesicle fluid. II. Role of water-soluble fraction of seminal vesicle fluid as a nonspecific immunomodulator

The suppressive mechanisms of T cells induced by water-soluble fraction of mouse seminal vesicle fluid (WSF-SVF) were investigated to clarify its immunological roles in the reproductive immunity. WSF-SVF inhibited the blastogenic responses to concanavalin A (Con A) or phytohemagglutinin (PHA) of T cells. Pretreatment of splenocytes with WSF-SVF did not suppress the blastogenesis of splenocytes to Con A when treated cells were washed before cultures. WSF-SVF did not inhibit the proliferation of Con A-activated splenocytes, that of listeria-immune splenocytes to listeral antigen and growth of tumor cells (Yac 1 cells, Ehrlich ascites carcinoma cells, EL 4 cells). Listerial antigen-specific immune response was not observed when mice were immunized with both listerial antigen and WSF-SVF, whereas it was observed when mice were immunized with only listerial antigen. WSF-SVF also significantly inhibited allogenic MLR. WSF-SVF did not adsorb Con A, and its suppressive activity was rather enhanced by heating at 56 degrees C for 30 min. These results suggest that WSF-SVF inhibits the stage of sensitization of T cells with antigen or stimulant, such as mitogen nonspecifically, without adsorption to antigen or mitogen, and its substance is stable.

Biological functions of mouse seminal vesicle fluid. I. Suppression of blastogenic responses of lymphocytes

The effect of mouse seminal vesicle fluid (SVF) on blastogenic response of splenocytes to mitogens was investigated. SVF significantly suppressed blastogenic response of splenocytes to concanavalin A and phytohemagglutinin in a dose-dependent manner, but blastogenic response to lipopolysaccharide was suppressed only at low, although significant, levels, even at high concentrations of SVF. Extensive dialysis did not reduce the capacity of SVF to inhibit blastogenesis of splenocytes. For elucidation of the mechanisms of suppression of blastogenic response, interleukin-2 (IL-2)-dependent cells were cultured in the presence of IL-2 and various concentrations of SVF. The presence of SVF did not inhibit the proliferative response of IL-2-dependent cells to IL-2. These results suggest that the suppression of blastogenic response of T lymphocytes to mitogens in seminal plasma is caused by an undialyzable component (or components) derived from seminal vesicle and is attributable to the alteration of receptors for mitogens or of IL-2 receptors that are expressed on stimulation by mitogens.

Effects of mouse testicular extract on immunocompetent cells

We investigated mouse testicular extract (TE) to clarify its biological functions in reproductive immunity. TE, at concentrations of 50-300 micrograms/ml, enhanced macrophage activities of spreading, glucose consumption, and cytostasis against a susceptible tumor cell line. On the other hand, TE inhibited concanavalin A (Con A)-induced T-cell blastogenesis in the dose range of 10-600 micrograms/ml. To elucidate the origin of TE, W/Wv mice, which genetically lack germ cells, were used. TE obtained from W/Wv mice enhanced the spreadability of macrophages and inhibited Con A-induced blastogenesis of T cells. The enhancement of macrophage spreading was only achieved by the interstitial fluid (IF), while the suppression of Con A-induced T-cell responses was detected in seminiferous tubule fluid (STF) as well as in IF. TE did not affect listerial antigen-specific responses of lymphocytes in vitro. These results suggest that TE has the capacity to regulate the biological responses associated with reproduction.

In vivo and in vitro immunosuppressions in mice by a 100-110-Kd fraction from boar seminal plasma

The activity of a 100-110-Kd immunosuppressive fraction (ISF), isolated from boar seminal plasma, was investigated in mice. In vitro, this fraction was found to inhibit a unidirectional mixed lymphocyte response and cell-mediated lymphocytotoxicity, as well as antisheep red blood cells (T-dependent) and antitrinitrophenylated lipopolysaccharide (T-independent) responses. The ISF also inhibited the macrophage phagocytosis of erythrocytes coated with IgG antibodies, but it did not suppress the natural killer activity. In vivo, ISF was found to lower both the primary responses to T-dependent and to T-independent antigens. Trypsin or pronase digestion of ISF provided active molecules of 30 Kd or 2-5 Kd respectively, thus showing that the activity is due to a protein. This ISF factor, capable of suppressing a wide variety of immune functions and remaining active after cleavage by proteases, could play a role in the lack of immune response against the spermatozoa present in the sow genital tract after intercourse. The use of this factor as a therapeutic agent in humans could eventually be considered after further molecular characterization.