Effects of stage of the estrous cycle and steroid treatment on uterine immunoglobulin content and polymorphonuclear leukocytes in cattle

Bovine reproductive immunoinfertility: pathogenesis and immunotherapy

Infertility is one of the primary factors for cattle reproduction in the present scenario. Reproduction-related immunoinfertility mainly involves immunization against the antigens related to reproductive hormones (LHRH, GnRH, Gonadal steroids, PGF2α and oxytocin), spermatozoa, seminal plasma and ovum. Anovulation, delayed ovulation, sperm immobilization, failure of fertilization, prolonged uterine involution, extended calving interval, prolonged post-partum estrus and reduced conception rate could be a result of immunoinfertility that occur due to the blockage of receptor site by antibodies formed against hormones, sperm and ovum. Immunoinfertility can be treated in the animal by giving sexual rest to females, by using various reproductive technologies such as in-vitro fertilization, gamete intra fallopian tube transfer, and intracytoplasmic sperm injection, sperm washing and by treating the animals with immunomodulators such as LPS, Oyster glycogen, etc. This review summarizes the different causes of bovine reproductive immunoinfertility and amelioration strategies to overcome it.

Type I interferon receptors and interferon-τ-stimulated genes in peripheral blood mononuclear cells and polymorphonuclear leucocytes during early pregnancy in beef heifers

This study characterised the expression of interferon (IFN)-τ-stimulated genes (ISGs) and Type I IFN receptors in circulating polymorphonuclear cells (PMNs) of beef heifers and compared it with expression in peripheral blood mononuclear cells (PBMCs) up to Day 20 of gestation. Nelore heifers (n=26) were subjected to fixed-time AI (FTAI) on Day 0. PMNs and PBMCs were isolated on Days 0, 10, 14, 16, 18 and 20 after FTAI. The abundance of target transcripts (ubiquitin-like protein (ISG15), 2'-5'-oligoadenylate synthetase 1 (OAS1), myxovirus resistance 1 (MX1), myxovirus resistance 2 (MX2), IFN receptor I (IFNAR1) and IFN receptor 2 (IFNAR2)) was determined using real-time quantitative polymerase chain reaction and compared between pregnant (n=8) and non-pregnant (n=9) females. In both PBMCs and PMNs, ISG15 and OAS1 expression was greater in pregnant than non-pregnant heifers on Days 18 and 20. There were no significant differences in the expression of ISGs between PBMCs and PMNs. A time effect on expression was found for IFNAR1 in PBMCs and IFNAR2 in PMNs, with decreased expression of both genes on Days 18 and 20. When the expression of these genes was compared between cell types only in pregnant heifers, IFNAR2 expression in PMNs had an earlier decrease when compared to its expression in PBMCs, starting from Day 18. In conclusion, PMNs do not respond earlier to the conceptus stimulus, and ISG15 and OAS1 expression in both PMNs and PBMCs can be used as a suitable marker for pregnancy diagnosis on Days 18 and 20. In addition, gestational status did not affect IFNAR1 and IFNAR2 expression, but IFNAR2 showed a distinct response between PMNs and PBMCs of pregnant heifers.

Ovarian function and the establishment and maintenance of pregnancy in dairy cows with and without evidence of postpartum uterine disease

Uterine disease early postpartum reduces fertility during the breeding period. One potential mechanism involves the reduced functional capacity of the uterus to support pregnancy. A second potential mechanism involves damage to ovarian follicles associated with systemic inflammation. We categorized lactating Holstein cows into healthy (n = 63) and diseased (n = 39) uterus groups based on the percentage of polymorphonuclear neutrophils in the uterine lumen during the second and third month postpartum and evaluated the functionality of their ovaries and their capacity to establish and maintain pregnancy. Cows were enrolled in a timed artificial insemination protocol (Presynch Ovsynch) so that the first artificial insemination was approximately 75 d postpartum. Ovarian follicles and corpora lutea were counted and measured using transrectal ultrasound, ovulatory responses were assessed, and luteal phase progesterone concentrations were measured. Pregnancy was detected on d 18, 20, 22, 25, 32, and 45 through chemical (d 18 to 25) or ultrasonographic methods (d 32 and 45). The percentage of cows ovulating during the Presynch period; the number, diameter, and ovulatory capacity of follicles during the Ovsynch period; and plasma progesterone concentrations following ovulation were similar for healthy and diseased cows. The initial period of pregnancy establishment (d 18 to 22) appeared to be unaffected by disease because a similar percentage of healthy and diseased cows were pregnant during this period. Embryonic loss occurred in both healthy and diseased cows after d 22. Based on a relatively small number of pregnancies (n = 30 healthy and n = 17 diseased), the cumulative embryonic loss after d 22 was greater in diseased compared with healthy cows. In short, uterine disease as defined in this study did not affect cyclicity, ovarian follicular growth, or plasma progesterone concentrations. Percentages of healthy and diseased cows that were pregnant were similar from d 18 to 22 after artificial insemination. Greater embryonic loss was observed after d 22 in diseased compared with healthy cows, but this observation was based on a small number of pregnancies and should be studied further in larger trials with greater statistical power.

Immune status during postpartum, peri-implantation and early pregnancy in cattle: An updated view

Throughout the estrous cycle the mammalian endometrium undergoes morphological and functional changes that are essential for the establishment of pregnancy and proper ovarian and uterine functions. Among these changes, the most important are alterations in both inter- and intracellular signalling molecules, many of which modulate immune processes. In the endometrial tissue there are local innate (nonspecific) and adaptive (specific/acquired) response mechanisms which vary because of the endocrine status during the estrous cycle, pregnancy and postpartum period. Endometrial cells have responses that support the immune system by producing pro-inflammatory factors such as cytokines, sensors, effector molecules and chemokines. This response is important during gestation, pregnancy, and fetal growth, as well as in preventing infection, and immuno-rejection of the semi-allogeneic embryo. In dairy cows, both before and immediately after calving, there are marked changes in the values for hormonal and metabolic variables and the immune status is impaired. Thus, in several studies there has been assessment of the physiological and/or abnormal maternal immune changes and possible effects on dairy cow reproductive performance. The objective with this review is to summarize the novel information about the immune mechanisms involved during the postpartum period, subsequent peri-implantation period and pregnancy in dairy cows, and the possible effects on reproductive performance. This information provides for an enhanced understanding of the local and systemic immune responses associated with the metabolic and hormonal status of dairy cows, and alterations in the immune system of high producing cows and the possible effects on subsequent fertility.

Physiology and Endocrinology Symposium: maternal immunological adjustments to pregnancy and parturition in ruminants and possible implications for postpartum uterine health: is there a prepartum-postpartum nexus?

Establishment of microbial infections in the reproductive tract can have negative consequences for reproductive function of the postpartum female. Most periparturient cows experience bacterial contamination of the uterus after parturition, but only a fraction of these develop subclinical or clinical disease. It is not well understood why one female resolves uterine infections after parturition while another develops disease. Perhaps those that develop metritis or endometritis are exposed to a greater bacterial load at parturition than those that successfully restore the uterus to a healthy condition. A second possibility is that females that develop bacterial disease have compromised immune function, either systemically or in the reproductive tract and associated lymph nodes. Here, the possibility is raised that maternal immunological adjustments to the presence of the allogeneic conceptus may predispose some females to metritis or endometritis. Several regulatory processes ensure that adaptive immune responses against paternal antigens on the conceptus are downregulated during pregnancy. Among these are immunosuppressive effects of progesterone, local accumulation of immune cells that can inhibit inflammation and T cell responses, including M2 macrophages and γδ T cells, and differentiation of regulatory T cells to inhibit alloreactive lymphocytes. Some immunological adjustments to the conceptus also make the uterus more susceptible to bacterial infection. For example, progesterone not only depresses skin graft rejection but also reduces uterine capacity to eliminate bacterial infections. Macrophages of M2 phenotype can inhibit inflammation and facilitate persistence of some microbial infections. At parturition, immune defenses in the uterus may be further weakened by loss of the luminal epithelium of the endometrium, which is part of the innate immune system, as well as by disappearance of intraepithelial γδ T cells that produce the antibacterial proteins granulysin and perforin. It is currently not known whether molecules and cells that inhibit immune responses during pregnancy persist after parturition but, if so, they could contribute to compromised immune function in the uterus. It is hypothesized that individual variation in immune adjustments to pregnancy and parturition and the reversal of these changes in the postpartum period are important determinants of susceptibility of the uterus to infection.

Postpartum suppression of ovarian activity with a Deslorelin implant enhanced uterine involution in lactating dairy cows

Holstein cows received, subcutaneously a non-degradable implant containing 5mg of the GnRH agonist Deslorelin (DESL) or no implant (CON) at 2+/-1 days postpartum (dpp). All cows were injected with PGF(2alpha) at 9 dpp. Previous pregnant (PPH) and non-pregnant uterine horns (PNPH) were determined by palpation per rectum. In Experiment 1, cows [DESL implant (n=10) and CON (n=9)] were examined by ultrasonography to record ovarian structures (23, 30 and 37 dpp) and uterine horn and cervical diameters (16, 23, 30 and 37 dpp). Uterine tone was scored before ultrasonography. Vaginoscopy was conducted just after ultrasonography examination to assess cervical discharge and color of the external cervical os. Blood samples were collected on a weekly basis for hormonal analyses. In Experiment 2, cows [DESL implant (n=77) and CON (n=70)] were palpated per rectum and vaginoscopy at 30 dpp for scoring of uterine tone, uterine horns, cervical diameter, and discharge. Blood samples were collected only at 9 dpp. In Experiment 1, DESL-implant-treated cows had more Class 1 follicles (P<0.01), less Class 2 (P<0.01) and Class 3 follicles (P<0.01) and no corpus luteum (CL) formation (P<0.01). In CON cows, six of nine animals had visible CL at 25+/-7 dpp. At 9 dpp plasma concentration of E(2), P(4) (P<0.01) and PGFM (P<0.05) were less in the DESL-implant treatment group. Diameter of PPH (P<0.01), PNPH (P<0.01) and cervix (P=0.08) were less in the DESL-implant treatment associated with greater uterine tone (P=0.07). The DESL-implant cows had a greater frequency of clear cervical discharge (P=0.09) and pink cervical os (P=0.06). In Experiment 2, plasma concentrations of PGFM were less at 9 dpp in DESL-implant treatment (P<0.01). Diameters of the PPH (P<0.01) and PNPH (P<0.01) were less and more uterine tone (P<0.01) in the DESL-implant treatment. Diameter of cervix and frequency of a cervical discharge score did not differ between treatments. Treatment with non-degradable Deslorelin (5mg) implant during postpartum: (1) suppressed ovarian follicular development, (2) enhanced physical involution of the uterus and cervix, (3) increased tone of the uterine wall, (4) decreased frequency of purulent cervical discharges, and (5) reduced inflammatory processes of the reproductive tract.

The immune status of the bovine uterus during the peripartum period

The post-partum period in cattle is characterised by an increased risk of infection of the uterus, as the anatomical barriers are broached during parturition and remain open for several days. Infection of the uterus is largely influenced by the balance between bacterial contamination and the local and systemic immune status during pregnancy and around parturition. Infectious diseases are more prevalent during this period, because of an impaired immune status before and immediately after parturition. Neutrophils play a primary role in the defence of the uterus against infection. Influx of neutrophils into the uterus is thought to be mediated by chemoattractants, chemokines and adhesion molecules, such as beta2-integrin (complement receptor 3) and L-selectin (CD62L). Other cellular components activated in the uterus during this period include lymphocytes, eosinophils, mast cells and macrophages. The major classes of immunoglobulins (IgM, IgA and IgG), either by passive diffusion or local production, play an important protective role in the uterus by acting as opsonins to enhance phagocytosis, stimulating the complement pathways or blocking pathogens from adhering to mucosal surfaces. Endometrial cells express toll-like receptor 4 (TLR4), which recognises lipopolysaccharides of Escherichia coli and other Gram negative bacteria, the most common causes of bovine endometritis. Activation of TLR4 triggers the production of tumour necrosis factor alpha and other pro-inflammatory cytokines. The periparturient period is also characterised by an increased secretion of prostaglandin F(2alpha), which enhances uterine immune defences.

Impact of estrous synchronization methods on cellular proportions in cervical mucus and serum hormone concentrations

The objective of this study was to examine cytological changes of cervical mucus following the induction of estrus with intra-vaginal drug release (CIDR) devices in dairy cows. Sixty healthy Holstein Frisian cows, averaging 80 (+/-10) days post-partum, were selected from a commercial dairy farm around Shiraz. Cows in the control group were synchronized by the Ovsynch protocol. Cows in the second group (OV+CIDR) were subjected to the same Ovsynch protocol but in addition were administered a progesterone-releasing CIDR. Cows in the third group (OV+S-CIDR) were subjected to Ovsynch procedures but received the skeleton of a CIDR device, which did not release progesterone. Cows in the fourth group (E2+CIDR) received a progesterone releasing CIDR but were injected with estradiol benzoate. Cows in group 5 (E2+S-CIDR) received a CIDR skeleton and estrodial benzoate. CIDR devices were removed from cows in groups 2-4 and all cows were injected with PGF2alpha on day -3. Blood samples and cervical mucus discharges were collected from all cows on days -10, -3, 0 and 12 relative to AI. On the day of AI, the mean+/-S.D. percentage of neutrophils was significantly higher (p<0.05) in the S-CIDR+OV and S-CIDR+E2 groups than in Ovsynch group. Comparing the percentage of neutrophils in cervical mucus of Ovsynch group (less than 1%) with that of other treatment groups on the day of AI (from 5 to 39%) revealed the influential effect of a CIDR device on the reproductive tract. Results of the current study did not reveal hormonal effects but did identify mechanical effects of CIDRs on cell percentages in cervical mucus. The hormonal effects were probably masked by mechanical effects. Therefore, we were not able to confirm hormonal effects on proportions of different cells in cervical mucus. Consequently, additional research on hormonal effects and the mechanical effects of CIDR on the uterus is required.

Prostaglandin F2alpha Upregulates Uterine Immune Defenses in the Presence of the Immunosuppressive Steroid Progesterone

PROBLEM

Uterine infections often develop in some livestock species during the first luteal phase postpartum. Exogenous prostaglandin F(2alpha) (PGF(2alpha)) induces luteolysis, reduces progesterone, and enables the uterus to resolve infections. However, the effects of PGF(2alpha) on luteal function and on immune functions are confounded. These effects must be disentangled to determine whether alternatives to antibiotic treatments can be successfully developed.

METHOD OF STUDY

Treatments were in a 2 x 2 x 2 factorial arrangement. Main effects were ovariectomy or sham on day 0 (i.e. estrus), exogenous progesterone or sesame oil from day 0 to 11, and exogenous PGF(2alpha) or saline on day 9. Intrauterine inoculations with Arcanobacterium pyogenes and Escherichia coli were administered on day 6.

RESULTS

Ewes treated with exogenous PGF(2alpha) either did not have uterine infections, infections were less severe, or infections were resolving when uteri were examined on day 12, despite increased progesterone.

CONCLUSIONS

Exogenous PGF(2alpha) has effects on the resolution of uterine infections that are independent of its effects on luteal progesterone production.

Uterine Response to Multiple Inoculations with Arcanobacterium pyogenes and Escherichia coli in Nulliparous Ewes

PROBLEM

Uterine infections seem more severe in nulliparous animals. Our objective was to determine whether intrauterine inoculation of nulliparous ewes with Arcanobacterium pyogenes and Escherichia coli would produce an antibody response and reduce the severity of subsequent infections.

METHOD OF STUDY

Nulliparous ewes (n = 9/treatment) received (i) 'primary intrauterine inoculation' with phosphate-buffered saline (PBS) and 'secondary intrauterine inoculation' with PBS; (ii) primary PBS-secondary 75 x 10(7) cfu of A. pyogenes and 35 x 10(7) cfu of E. coli (PBS-Bacteria); (iii) primary bacteria-secondary PBS; or (iv) primary bacteria-secondary bacteria (Bacteria-Bacteria).

RESULTS

Inoculations evoked an antibody response. Postmortem examinations 6 days after the secondary inoculation indicated that PBS-treated ewes did not develop uterine infections, but all bacteria-treated ewes did. Infections were either less severe or closer to resolution in Bacteria-Bacteria than they were in PBS-Bacteria ewes.

CONCLUSIONS

Intrauterine inoculation of nulliparous ewes with A. pyogenes and E. coli evokes an antibody response that may help the uterus reduce the severity of subsequent infections.

Steroidal regulation of uterine immune defenses

Progesterone suppresses uterine immune defenses and predisposes postpartum animals to nonspecific uterine infections. Progesterone can also suppress uterine eicosanoid synthesis. This effect of progesterone seems to be an important factor in the onset of uterine infections because eicosanoids can enhance uterine immune defenses. In fact, exogenous prostaglandin F(2alpha) (PGF(2alpha)), an eicosanoid that stimulates uterine PGF(2alpha) production, enhances uterine immune defenses and promotes the ability of ewes and sows to resolve uterine infections, even when progesterone is maintained at luteal phase concentrations. Prostaglandin F(2alpha) is also a proinflammatory molecule that stimulates the production of proinflammatory cytokines and may enhance uterine production of leukotriene B(4) (LTB(4)), which stimulates various neutrophil functions. Neutrophils seem to mount the initial response to bacteria that enter the uterus, and proinflammatory cytokines and LTB(4) enhance phagocytic activity of neutrophils. Even though there are clear associations among PGF(2alpha), LTB(4), proinflammatory cytokines, phagocytosis, and the ability of the uterus to resist or resolve infections, the mechanisms of action of exogenous PGF(2alpha) in mitigating the immunosuppressive effects of progesterone have not yet been defined. However, defining the PGF(2alpha) mechanisms should yield important new information that can be used to develop novel prevention and treatment strategies that do not rely on antibiotic and antimicrobial compounds for managing uterine infections.

Comparison of ceftiofur hydrochloride and estradiol cypionate for metritis prevention and reproductive performance in dairy cows affected with retained fetal membranes

The objective of this study was to compare the effect of ceftiofur hydrochloride and estradiol cypionate (ECP) administration for metritis prevention and reproductive performance in dairy cows affected with retained fetal membranes (RFMs). After parturition, 97 dairy cows affected with RFM from a single dairy herd were randomly allocated to 1 of 3 treatment groups. Cows in-group 1 (n=31) were treated daily for 5 days with ceftiofur hydrochloride (2.2mg/kg, i.m.); cows in group 2 (n=33) were treated once with ECP (4 mg, i.m.); and cows in group 3 (n=33) were not treated. The proportion of cows with metritis, uterine involution patterns and the calving-to-conception interval were compared between groups. The proportion of cows that developed metritis was significantly different (P<0.05) in cows treated with ceftiofur hydrochloride (13%), compared with cows treated with ECP (42%) or cows that received no treatment (42%). Uterine involution patterns (i.e. median time to complete retraction of the uterus and mean diameter measure of cervix and uterine horns) were not significantly different between groups. Cows treated with ECP were 0.40 times as likely to conceive as control cows (P=0.05); median time to conception in cows treated with ECP (192 days) was longer, compared to control cows (124 days). We conclude that systemic administration of ceftioufur hydrochloride is beneficial for prevention of metritis, but its effect on reproductive performance was not significantly different to that of ECP or no treatment. In addition, administration of ECP did not have beneficial effects on metritis prevention and reproductive performance.

Reproductive responses of early postpartum dairy cattle to continuous treatment with a GnRH agonist (deslorelin) for 28 days to delay the resumption of ovulation

An experiment was conducted to investigate the potential of chronic delivery of a potent GnRH agonist (deslorelin) via subcutaneous implants to delay the resumption of ovulatory cycles in postpartum dairy cattle. Cows received either a single deslorelin implant (n=40; DES) within 7 days of calving or were untreated (n=24; CON). Blood samples were collected thrice weekly during the period the implants were in place. Plasma concentrations of progesterone (P4) and 17beta-oestradiol (E2) were measured along with selected serum metabolites. Implants were removed after 28 days and cattle monitored daily for behavioral oestrus. Serial weekly blood samples were collected to detect the occurrence of ovulation. Cows were artificially inseminated as they were detected in oestrus from 30 days after implant removal. Pregnancy status was subsequently determined by manual palpation of uterine contents at strategic intervals. Insertion of implants induced ovulation in 3/40 cows as determined by a rise in progesterone 7 days later. Deslorelin implants delayed the onset of ovulatory cycles compared with untreated herdmates (mean 43.4+/-4.2 versus 57.3+/-1.6 days postpartum; P<0.001). A noticeable delay of at least 12 days was observed between implant removal and the first animals ovulating. Mean plasma E2 concentrations during the period the implants were in place were similar for DES and CON cows that experienced a prolonged spontaneous postpartum anoestrus (low P4 >60 days), although both groups had concentrations only 20% of CON cows that had ovulated prior to 30 days postpartum. The patterns of recovery following implant removal were highly variable. A number of DES cows showed a low and transient rise in plasma progesterone around 21 days after implant removal. Some cows displayed oestrus but did not appear to form a fully functional corpus luteum with this phenomenon being more prevalent among DES cows (7 of 37 versus 1 of 21; P<0.05). Overall, significantly more DES cows were detected in oestrus without ovulating compared to CON cows. Final pregnancy rates did not differ between DES and CON groups. The mean time to conception for DES cows was longer (21.2+/-5.6 versus 41.1+/-7.4 days, CON versus DES; P<0.01). This difference was not present if the time from first ovulation to conception was compared (50.5+/-5.3 versus 43.5+/-9.3 days, CON versus DES; P>0.05). Deslorelin implants provided a reliable method of inducing anoestrus when treatment was initiated prior to 3 days postpartum. A variable pattern of recovery was observed which delayed conception but did not ultimately reduce the final proportion pregnant at the completion of mating. The study demonstrates the potential of GnRH agonists to control postpartum reproductive function to manipulate the fertility of dairy cows.

Lochial secretions of Escherichia coli- or Arcanobacterium pyogenes-infected bovine uteri modulate the phenotype and the functional capacity of neutrophilic granulocytes

It has been suggested that in cases of puerperal endometritis of cattle infected with Escherichia coli and Arcanobacterium pyogenes, the neutrophils are compromised in their defense capacity or downregulated functionally. In addition to direct bacterial effects, contents of lochial secretions and secreted products of locally activated polymorphonuclear neutrophilic granulocytes (PMNs) may also account for changes in function of freshly immigrating neutrophils. In this study, lochial secretions were obtained from healthy cows and from cows infected by E. coli or A. pyogenes. Separated uterine PMN of infected cows displayed an altered phenotype and function which correlated with the degree of bacterial contamination. Concurrently tested circulating PMN showed no such changes. Infected lochial secretions sterilized by filtration also changed the phenotype of blood PMN. Lochial secretions of healthy cows displayed only minor effects. The effects on PMN function in infected cows varied: ingestion was less affected, whereas generation of reactive oxygen species (ROS) was severely depressed. Concurrently tested purified bacterial products (solubles and fragments) of E. coli and A. pyogenes did not induce the phenotypical and functional changes observed in blood PMN. Since infected lochia also contained high numbers of immigrated and probably activated PMN, the influence of supernatants from phorbol myristate acetate-activated PMN were tested on freshly isolated blood PMN. Such supernatants also increased the expression of certain surface molecules and inhibited the ROS generation. Thus, reduced function and altered phenotypes of PMN which immigrate into the uteri of cows with bacterial endometritis is due not only to interactions with bacteria or bacterial products, but is also to the uterine milieu.

Some aspects of immunology of the bovine uterus related to treatments for endometritis

Endometritis in breeding cattle occurs during the postpartum period, and is associated primarily with contamination of the reproductive tract involving Arcanobacter pyogenes (formerly Actinomyces pyogenes) together with Gram-negative anaerobes. Polymorphonuclear inflammatory cells (PMNs) contribute partly to the defense mechanisms against micro-organisms contaminating the vagina and uterine lumen, whose phagocytic activity depends on bacterial opsonisation by humoral antibodies; significant numbers of lymphocytes are also present. Whilst leukocyte numbers in the uterine lumen are relatively high during metoestrus and dioestrus compared to other phases of the oestrous cycle, their functional activity is unaffected. Humoral antibody concentrations in the reproductive tract are stimulated following exposure to local antigen, and the response is site dependent; of the several different classes of immunoglobulins, IgG predominates in the uterus and IgA the vagina. Only a portion of the total IgG1 found on the uterine lumen is synthesised locally in the endometrium, the remainder and all of the IgG2 is derived from the local uterine blood supply. Generally, concentrations of immunosuppressant proteins present in the uterine lumen increase under progesterone dominance, and these inhibit lymphocyte proliferation, making the uterus more susceptible to infection. The relationship between uterine susceptibility to micro-organism contamination and the luteal phase of the oestrous cycle is still unclear. Intrauterine infusion of immunomodulators such as E. coli lipopolysaccharides (LPS) or oyster glycogen, in healthy cows and those with endometritis, stimulates leukocytes to migrate into the uterine lumen. At a dosage rate of 100 microg, lipopolysaccharides are not absorbed by the healthy endometrium and do not alter the oestrous cycle length. It is unknown, whether a similar dose can be absorbed through an inflamed endometrium in naturally occurring cases of endometritis to cause systemic illness. Currently, prostaglandin F2alpha is recommended for treating endometritis in both cycling and non-cycling cows, but its mode of action in non-cycling cows is not fully understood. The efficacy of endometritis treatment using an intrauterine infusion of an immunomodulator in cases occurring naturally has not been determined on a large scale.

Pregnancy-specific protein B (bPSPB) and progesterone monitoring of post-partum dairy cows with placental retention

The relationship between placental retention, progesterone and pregnancy-specific protein B (bPSPB) was determined in 60 calving Holstein cows. The cows were divided into two groups with placental retention (WPR, n = 16) and no placental retention (NPR, n = 44). Every 4 days, until 60 days post-partum, blood samples were taken and the uteri were checked using ultrasonographv. The puerperal characteristics of NPR and WPR were as follows: mean days of abnormal vaginal discharge: 20.2+/-5 versus 35.6+/-7 (P < 0.01); mean intervals to uterine involution: 21.4+/-3.7 versus 27.6+/-7.6 days (P < 0.01); rate of endometritis: 25 versus 100% (P < 0.01). The mean numbers of oestrus cycles per cow were 1.75+/-0.5 versus 0.85-/+0.9 (P < 0.05) and the mean durations of the first oestrus cycle were 18+/-3.5 versus 16+/-2.1 days (P > 0.05). The mean intervals to first ovulation were 21.5+/-8.4 versus 35+/-19 days (P < 0.01). bPSPB blood concentrations were higher in the WPR group at calving with 955+/-170 versus 750+/-205 ng/ml (P < 0.01) and also during the first 32 days post-partum with 173.68+/-47.3 versus 131.0+/-29.2 ng/ml (P < 0.01). The mean bPSPB half-life was similar in the two groups: 6.9+/-2.5 versus 6.5+/-2.1 days (P > 0.05). In conclusion, it was found that placental retention was associated with a higher rate of endometritis, a lower number of cycles, longer interval to first post-partum ovulation and higher concentration of bPSPB at calving and during the post-partum period. The positive relationship between bPSPB concentrations and calf birth weight and their association with post-partum pathological events may be useful in monitoring animals presenting high concentrations at calving.

Influence of Escherichia coli and Arcanobacterium pyogenes isolated from bovine puerperal uteri on phenotypic and functional properties of neutrophils

When cows develop endometritis after birth, Escherichia coli and Arcanobacterium pyogenes are usually the most prominent bacteria present in bovine uterine lochial secretions. A. pyogenes alone is rarely found in the course of a disturbed puerperium. This was confirmed in this study, since average and high-grade uterine contaminations were always associated with the presence of both bacteria. The contamination grade was positively correlated with uterine polymorphonuclear granulocyte (PMN) numbers and negatively correlated with blood PMN numbers. Whether E. coli and A. pyogenes affect the phenotype and function of bovine PMN in a similar or differential way was subject to in vitro studies. PMN were tested in the presence of washed bacterial fragments or culture supernatants taken as a source for soluble and/or secreted bacterial products. Fragments and soluble products differed only quantitatively in their effects on PMN. Usually, long-time exposure (24h) of PMN to fragments induced the strongest effects. Accelerated death of granulocytes was only moderately induced by both E. coli and A. pyogenes products. Both E. coli and A. pyogenes products induced the enhanced expression of a membrane molecule detected by mAb IL-A110 and of CD11b. Expression of other surface structures remained largely unchanged (MHC class I, CD11c). Functional parameters of PMN (phagocytosis; generation of reactive oxygen species, ROS; antibody-independent cellular cytotoxicity, AICC) generally declined after pre-incubation for 24h with products of E. coli or A. pyogenes. Interestingly, soluble products of A. pyogenes stimulated the phagocytosis of PMN. However, co-incubation with E. coli products abrogated this stimulatory effect. The results supply evidence for similar modes of action of the gram-negative E. coli and the gram-positive A. pyogenes on bovine PMN. Alterations in PMN function and phenotype are mainly triggered by direct contact between bacterial fragments and PMN. Inhibition experiments with polymyxin B demonstrated that E. coli-mediated effects were not solely due to the action of lipopolysaccharide. The dominant functional depression of neutrophils by E. coli products strengthens the suggestion that the earlier appearance of E. coli in the uterus may support the co-infection of this organ by A. pyogenes at later times.

Peripheral and intrauterine neutrophil function in the cow: the influence of endogenous and exogenous sex steroid hormones

It has been accepted for many years that the susceptibility of the genital tract to infection is reduced during the follicular phase compared with the luteal phase of the estrous cycle. Since the role of intrauterine neutrophils is paramount in the elimination of bacteria, it can be hypothesized that these differences in resistance to infection could be mediated by differences in uterine-derived neutrophil function. In order to test this hypothesis two groups of cows were used in this study. Group 1 cows (n=5) were studied at estrus, diestrus, after ovariectomy, after exogenous estradiol and after progesterone treatment, at which time they underwent intrauterine infusion with 1% oyster glycogen (OG) and a bacterial-free filtrate (BFF) of Actinomyces genes (BFF), the latter having been recovered from a clinical case of endometritis; neutrophils were harvested by flushing from the lumen 15 to 18 h later. A peripheral blood sample was collected at the time of flushing for the assay of estradiol and progesterone for a WBC and differential count and for the harvesting of neutrophils using a Percoll single-stage discontinuous gradient. After the recovery of the cells they were re-suspended in HBSS. Group 2 (n=4) were infused with BFF during during all reproductive states as Group 1, but with OG only after ovariectomy and after treatment with progesterone and estradiol. Neutrophil chemotaxis was assessed by measuring their migration using a modified Boyden chamber and Zymogen-activated serum as a chemoattractant. Phagocytic activity was measured by determining the number of Candida albicans ingested by each neutrophil after incubation. The percentage of kill was determined using a radiometric assay in which C. albicans was labeled with L-(5-3H) Proline. Peripheral WBC concentration was not influenced by the reproductive state of the cow; however, the mean neutrophil concentration was significantly different between the reproductive states (P<0.001) and between individual cows (P<0.001). In Group 1, there was little difference in the function of the peripheral and uterine neutrophils, and while there were differences in all 3 aspects of neutrophil function from both sources between reproductive states and individual cows, of which some were statistically significant, there was no consistent pattern. In Group 2, neutrophils recovered after the infusion of BFF had poorer function compared with those recovered after the infusion of OG. There was no consistent influence of the reproductive state or individual animal. The hypothesis that the influence of the reproductive state of the cow on the resistance of the uterus to infection is mediated by the inherent differences in either peripheral or intrauterine neutrophil function was not supported by this study.

Regulation of uterine immune function by progesterone--lessons from the sheep

Survival of the fetal allograft results from orchestrated adjustments in activity of maternal lymphoid cells as well as in trophoblast gene expression. One molecule that regulates uterine immune responsiveness is progesterone. In fact, uterine skin graft survival and susceptibility to bacterial infections are increased by progesterone. This review focuses on the role of progesterone in regulation of uterine immune function in the sheep. While the importance of progesterone as a regulator of immune function likely varies between species, concepts derived from the sheep model may prove pertinent to other species also. The actions of progesterone on uterine immune function in the ewe change during pregnancy. Before day 50 of gestation, i.e. when the uterus is still dependent upon the corpus luteum as a source of progesterone, concentrations of progesterone are probably not high enough at the maternal fetal interface to inhibit lymphocyte activation. During this early period of pregnancy, progesterone inhibits uterine immune function by inducing endometrial secretion of a protein called uterine milk protein (UTMP) that itself is inhibitory to lymphocyte function. After day 50 of pregnancy, it is likely that the placenta produces sufficient amounts of progesterone to directly inhibit lymphocyte proliferation. Additional inhibition is achieved because of sustained synthesis of UTMP. Accordingly, progesterone acts to regulate uterine immune function in ways that allows for inhibition of immune responses at the utero-placental interface without systemic immunosuppression.

Neutrophil migration into the uterine lumen of the cow: The influence of endogenous and exogenous sex steroid hormones using two intrauterine chemoattractants

Neutrophil migration into the uterine lumen in response to the intrauterine infusion of both an oyster glycogen suspension and a bacteria-free filtrate obtained after incubation of Actinomyces pyogenes in cooked meat medium was studied in 4 cows at estrus (Day 0) and at diestrus (Day 10). In addition, the same chemoattractants were used in 5 other cows following bilateral ovariectomy and after parenteral treatment with exogenous estradiol 17beta and progesterone in oil. Large numbers of cells (average viability >85%, purity 95%) were obtained with both chemoattractants. In cyclic and bilaterally ovariectomized cows bacteria-free filtrate produced a greater migratory response than oyster glycogen, and the differences were significant (P < 0.01 and P < 0.002, respectively). On Day 10 of the estrous cycle a higher number of neutrophils was recovered than on Day 0 following infusion of oyster glycogen and bacteria-free filtrate, and again the differences were significant (P < 0.003 and P < 0.001, respectively). Following treatment of ovariectomized cows with estradiol and progesterone, greater response was observed for progesterone than for estradiol after oyster glycogen and bacteria-free filtrate treatment with significant differences (P < 0.002 and P < 0.003, respectively). Both chemoattractants produced adequate numbers of viable neutrophils suitable for subsequent evaluation of their function in vitro. The increased neutrophil response induced by progesterone, both in normal cyclic cows and after ovariectomy following progesterone treatment, may be a compensatory one due to reduced neutrophil phagocytosis and bactericidal activity or to the suppression of other uterine defense mechanisms, since this response is inconsistent with the long-recognized observation that the uterus of the cow is more susceptible to infection in diestrus than in estrus.

Pharmacologic considerations in the management of peripartum conditions in the cow

As is true with the use of drugs in veterinary medicine in general, there are many controversial issues in the management of peripartum conditions in the cow. For example, the use of PG versus antibacterial drugs in the management of postpartum uterine infections has advocates for the use of either approach. Intrauterine versus systemic administration of antibacterial drugs for the prophylaxis or treatment of postpartum metritis is another area of debate. Clearly, more research is needed in this area. Equally clearly, however, the research results that are available are being disregarded on a daily basis. In considering this discussion of the use of drugs in the peripartum period, one is struck by the frequency that optimum drug therapy of a condition relies on the extralabel use of nonapproved preparations. What guidelines are available to the practitioner in this regard? One example is lack of availability of appropriate dosage regimens or withdrawal times for food derived from treated animals. Unfortunately, pharmacokinetic and residue studies that would aid in establishing guidelines generally are not available and, in most instances, are not forthcoming. Extrapolation of data from other species to the ruminant or extrapolation of information from one drug to a related compound (such as prediction of residue and withdrawal data from an approved aminoglycoside, dihydrostreptomycin, to another unapproved drug, gentamicin) is fraught with difficulties. The need for research in this area is obvious, and lack of such information is one of the major dilemmas in trying to establish rational drug therapy in the food-producing animal. Recent developments in drug therapy have led to innovative approaches for the management of peripartum and other diseases in cattle. The use of PG in the treatment of reproductive disorders, so commonplace and widely accepted in contemporary veterinary practice, is a relatively recent approach that continues to be refined with the development of new, more potent, more specific PG analogs. What will be the role of ceftiofur, a potent, third-generation cephalosporin that currently is approved only for the treatment of respiratory infections in cattle, in the management of reproductive tract infections? The fluoroquinolones, which represent a novel approach to the control of infectious diseases, are being increasingly used in veterinary and human medicine, and one may predict that these powerful antimicrobial drugs will find application in bovine practice, including for the treatment of peripartum infections. Pharmacologic manipulation of immune and defense mechanisms also is an approach with some promise.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of antigen- and mitogen-induced activation of mouse splenocytes by uterine secretions from pregnant and progesterone-treated ewes

Pregnant and progesterone-treated, ovariectomized ewes accumulate secretory products in the uterus that are immunosuppressive in mitogen-stimulated and mixed lymphocyte sheep cell cultures. In this study, uterine secretions from pregnant (Preg-UTM) and progesterone-treated, ovariectomized (P-UTM) ewes were equally effective in suppressing 3H-Tdr incorporation in mouse spleen cells stimulated with PHA. P-UTM inhibited PHA-stimulated, purified T-cells and separated L3T4+ and Lyt2+ T-cell subpopulations more than Preg-UTM, however. Both fluids were slightly inhibitory to conA-stimulated mouse spleen cells, enriched T-cells, and Lyt2+ T-cells but neither inhibited L3T4+ T-cells. For LPS-stimulated cells, P-UTM caused more suppression than Preg-UTM of enriched B-cells; however, suppression was similar for the two fluids on unseparated splenic cells. In antigen-stimulated mouse spleen cell cultures, both fluids inhibited antibody-forming cell responses to sheep erythrocytes, a thymus-dependent antigen, but neither suppressed antibody-forming cell responses to TNP-Ficoll, a thymus-independent antigen. These data indicate that uterine secretions in the ewe produced under the influence of progesterone or pregnancy contain immunoregulatory molecule(s) which modulate the activity of both homologous sheep and unrelated mouse lymphocytes. These studies establish the mouse as a useful in vivo model for studying the biological actions of these molecules.