Embryo-maternal communication in dogs: Immune system related factors

In the bitch, establishment of pregnancy is believed to be mainly initiated by the free-floating embryo in the uterus that is under progesterone influence. As in other species, the active participation of the embryo is no longer questioned. Secretory products are transported to the embryo-maternal interface and contribute to extra-cellular matrix (ECM) degradation, a change in the intrauterine immune milieu towards a reduction of immune cells and a change in lymphocyte subsets, cell differentiation, angiogenesis, and the balance between proliferation and apoptosis. For cell-to-cell communication between embryo and maternal tissue, biomolecules inclusive microRNAs might be transported and exchanged via extracellular vesicles (EVs) as in other species. Maternal acceptance of the fetal allograft is vital for the establishment of pregnancy. Findings so far indicate that the embryo avoids attacks from the maternal system via passive and active mechanisms. One hypothesis is that expression or suppression of surface molecules help the canine embryo to hide from the maternal immune system on one side and to actively destroy cytotoxic immune cells on the other side; there are further clues that the canine embryo blocks activation of intrauterine leukocytes. Intracellular repair mechanisms via heat shock proteins (HSP) are candidates under investigation. The presence and function of immunomodulatory intrauterine cells like Treg cells and their interaction with the embryo have been intensely studied in other species but remains to be investigated in the canine preimplantation uterus.

Short-term energy restriction during late gestation of beef cows decreases postweaning calf humoral immune response to vaccination

Our objectives were to evaluate the pre- and postweaning growth and measurements of innate and humoral immune response of beef calves born to cows fed 70 or 100% of NEm requirements during the last 40 d of gestation. On d 0 (approximately 40 d before calving), 30 multiparous Angus cows pregnant to embryo transfer (BW = 631 ± 15 kg; age = 5.2 ± 0.98 yr; BCS = 6.3 ± 0.12) were randomly allocated into 1 of 10 drylot pens (3 cows/pen). Treatments were randomly assigned to pens (5 pens/treatment) and consisted of cows limit-fed (d 0 to calving) isonitrogenous, total-mixed diets formulated to provide 100 (CTRL) or 70% (REST) of daily NEm requirements of a 630-kg beef cow at 8 mo of gestation. Immediately after calving, all cow-calf pairs were combined into a single management group and rotationally grazed on tall fescue pastures (6 pastures; 22 ha/pasture) until weaning (d 266). All calves were assigned to a 40-d preconditioning period in a drylot from d 266 to 306 and vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea virus (BVDV), , and spp. on d 273 and 287. Blood samples from jugular vein were collected from cows on d 0, 17, and 35 and from calves within 12 h of birth and on d 266, 273, 274, 276, 279, and 287. By design, REST cows consumed less ( ≤ 0.002) total DMI, TDN, and NEm but had similar CP intake ( = 0.67), which tended ( = 0.06) to increase BW loss from d 0 to calving, than CTRL cows (-1.09 vs. -0.70 ± 0.14 kg/d, respectively). However, gestational NEm intake did not affect ( ≥ 0.30) plasma concentrations of cortisol, insulin, and glucose during gestation and BCS at calving as well as postcalving pregnancy rate, BW, and BCS change of cows. Calf serum IgG concentrations and plasma concentrations of haptoglobin and cortisol at birth as well as calf pre- and postweaning BW and ADG did not differ ( ≥ 0.15) between calves born to REST and CTRL cows. However, calf postweaning overall plasma concentrations of cortisol; plasma haptoglobin concentrations on d 274, 276, and 279; and serum BVDV-1a titers on d 306 were less for REST calves than for CTRL calves ( ≤ 0.05). Hence, a NEm restriction to 70% of daily requirements during the last 40 d of gestation had minimal effects on cow precalving growth and did not affect postcalving cow growth and reproductive performance. However, it decreased postweaning vaccination-induced humoral immunity, inflammatory, and physiological stress responses of calves.

Impact of in vitro treatments of physiological levels of estradiol and progesterone observed in pregnancy on bovine monocyte-derived dendritic cell differentiation and maturation

The specific factors which regulate differentiation and maturation of dendritic cells in bovine pregnancy remain unclear. We evaluated the influence of physiologically relevant in vitro treatments of progesterone (PG) and estradiol (E2) observed in late pregnancy on the differentiation and maturation of CD14+ monocyte-derived dendritic cell (moDC) from non-pregnant, lactating dairy cows (n=7). We found that moDC differentiated in the presence of both E2 and PG had impaired E. coli-induced phenotypic maturation, specifically a significant reduction in CD80 and MHC II expression. Contrary to our previous work characterizing moDC from late gestating dairy cattle, we did not observe an increase in CD14 expression relative to the untreated control; this increase was only observed in the current data in the dexamethasone-treated moDC. The moDC treated with a combination of both E2 and PG had significantly greater upregulation of anti-inflammatory cytokine IL-10 relative to the untreated control, but TNFα production was not suppressed; only dexamethasone-treated moDC showed abrogated TNFα production. These data suggest moDC may be regulated by E2 and PG to hinder phenotypic maturation and regulate inflammatory responses. Pregnancy-associated hormone profiles appear to be involved in the generation of maternal immune tolerance in pregnancy. These hormone-facilitated changes to moDC in pregnancy may also impede optimal immune responses to both invading pathogens and routine vaccinations administered in late gestation through limited antigen presentation and increased anti-inflammatory cytokine production. These results provide insight into maternal immune modulation and elucidate potential immune changes necessary to facilitate bovine pregnancy.

Murine uterine decidualization is a novel function of autoimmune regulator-beyond immune tolerance

PROBLEM

Autoimmune polyendocrinopathy, candidiasis, and ectodermal dystrophy (APECED, APS-1) patients characterized by Aire (autoimmune regulator) mutations and Aire homozygous knockouts (Aire(-/-) ) exhibit infertility. It is not clear as to what contributes to infertility in the above.

METHOD OF STUDY

This study investigates the expression of "AIRE in the uterus" and its contribution to early pregnancy of mice by using quantitative real-time PCR analysis, immunohistochemistry, Western blotting, and in vivo Aire silencing experiments.

RESULTS

Aire (Isoform 1a) is expressed in the uterus during the "window of implantation" and decidualization. In vivo Aire silencing interfered with formation of implantation sites and stromal cell transformation by regulating bone morphogenetic protein-2,4 (Bmp2, Bmp4), homeobox A10 (Hoxa10), and insulin-like growth factor-binding protein 1(Igfbp1) leading to pregnancy failure.

CONCLUSION

Our consolidated results on extrathymic uterine expression of AIRE during early pregnancy and decidualization and impaired fertility on in vivo silencing are suggestive of its importance in pregnancy via a role beyond immune tolerance.

Pregnancy boosts vaccine-induced Bovine Neonatal Pancytopenia-associated alloantibodies

Although maternal vaccination is generally considered to be safe, the occurrence of Bovine Neonatal Pancytopenia (BNP) in cattle shows that maternal vaccination may pose a risk to the offspring. Pregsure BVD-induced maternal alloantibodies cause BNP in newborn calves. The occurrence of BNP years after last Pregsure BVD vaccination indicates that alloantibody levels may remain high in dams. Since pregnancy induces alloantibodies we hypothesized that pregnancy boosts the vaccine-induced alloantibody response. Alloantibody levels in Pregsure BVD-vaccinated dams increased from conception towards the end of gestation and declined after parturition. In parallel, BVDV-antibody levels remained constant, indicating that there is specific boosting of alloantibodies. Since the rise in alloantibodies coincides with pregnancy and other alloantigen sources were excluded, we concluded that fetal alloantigens expressed during pregnancy boost the alloimmune response in the dam. These results help explain why BNP cases occur even years after Pregsure BVD has been taken off the market.

Extracellular ATP decreases trophoblast invasion, spiral artery remodeling and immune cells in the mesometrial triangle in pregnant rats

INTRODUCTION

Preeclampsia is characterized by deficient trophoblast invasion and spiral artery remodeling, a process governed by inflammatory cells. High levels of the danger signal extracellular adenosine triphosphate (ATP) have been found in women with preeclampsia and infusion of ATP in pregnant rats induced preeclampsia-like symptoms such as albuminuria and placental ischemia. We hypothesized that ATP inhibits trophoblast invasion and spiral artery remodeling and affects macrophages and natural killer (NK) cells present in the rat mesometrial triangle.

METHODS

Pregnant rats were infused with ATP or saline (control) on day 14 of pregnancy. Rats were sacrificed on day 15, 17 or 20 of pregnancy and placentas with mesometrial triangle were collected. Sections were stained for trophoblast cells, α-smooth muscle actin (spiral artery remodeling), NK cells and various macrophage populations. Expression of various cytokines in the mesometrial triangle was analyzed using real-time RT-PCR.

RESULTS

ATP infusion decreased interstitial trophoblast invasion on day 17 and spiral artery remodeling on day 17 and 20, increased activated tartrate resistant acid phosphatase (TRAP)-positive macrophages on day 15, decreased NK cells on day 17 and 20, and decreased inducible nitric oxide synthase (iNOS)-positive and CD206-positive macrophages and TNF-α and IL-33 expression at the end of pregnancy (day 20).

DISCUSSION

Interstitial trophoblast invasion and spiral artery remodeling in the rat mesometrial triangle were decreased by infusion of ATP. These ATP-induced modifications were preceded by an increase in activated TRAP-positive macrophages and coincided with NK cell numbers, suggesting that they are involved.

CONCLUSION

Trophoblast invasion and spiral artery remodeling may be inhibited by ATP-induced activated macrophages and decreased NK cells in the mesometrial triangle in rat pregnancy.

The interleukin-1β system in the corpora lutea of pigs during early pregnancy and the estrous cycle

Expression of mRNAs encoding interleukin-1β (IL-1β), IL-1β receptor I (IL-1RI), IL-1 receptor accessory protein (IL-1RAcP) and IL-1 receptor antagonist (IL-1Ra), as well as synthesis of IL-1β and IL-1RI proteins, were examined in the corpus luteum (CL) during critical stages of CL activity on days 10-16 of pregnancy and 2-16 of the estrous cycle. Luteal cells were cultured in vitro with IL-1β, and the effect on release of steroid hormones was determined. Expression of the IL-1β system in the CL changed significantly during pregnancy and the estrous cycle. IL-1β, IL-1RI, and IL-1Ra mRNA levels were elevated on days 12-13, whereas IL-1RAcP mRNA was increased on days 15-16 of pregnancy. In cyclic CL, expression of IL-1β, IL-1RI, and IL-1RAcP mRNAs was increased on days 12-13. IL-1β and IL-1RI protein were highest in the CL on days 10-11 and 8-11 of pregnancy and the estrous cycle. Luteal cells harvested from gravid and cyclic CL produced IL-1β in vitro. IL-1β increased progesterone and estradiol-17β (E2) release by luteal cells on days 10-16 and 10-11 of pregnancy, respectively and on days 2-11 of the estrous cycle. IL-1β decreased the level of E2 produced by regressed CL (days 15-16). Expression of the IL-1β system in CL and IL-1β secretion from luteal cells changed depending on the status of the CL. These data show that IL-1β may be involved in intraluteal, luteotrophic regulation of CL functions in gravid and cyclic pigs.

Pregnancy and pregnancy-associated hormones alter immune responses and disease pathogenesis

During pregnancy, it is evolutionarily advantageous for inflammatory immune responses that might lead to fetal rejection to be reduced and anti-inflammatory responses that promote transfer of maternal antibodies to the fetus to be increased. Hormones modulate the immunological shift that occurs during pregnancy. Estrogens, including estradiol and estriol, progesterone, and glucocorticoids increase over the course of pregnancy and affect transcriptional signaling of inflammatory immune responses at the maternal-fetal interface and systemically. During pregnancy, the reduced activity of natural killer cells, inflammatory macrophages, and helper T cell type 1 (Th1) cells and production of inflammatory cytokines, combined with the higher activity of regulatory T cells and production of anti-inflammatory cytokines, affects disease pathogenesis. The severity of diseases caused by inflammatory responses (e.g., multiple sclerosis) is reduced and the severity of diseases that are mitigated by inflammatory responses (e.g., influenza and malaria) is increased during pregnancy. For some infectious diseases, elevated inflammatory responses that are necessary to control and clear a pathogen have a negative consequence on the outcome of pregnancy. The bidirectional interactions between hormones and the immune system contribute to both the outcome of pregnancy and female susceptibility to disease.

Passive transfer of maternal GnRH antibodies does not affect reproductive development in elk (Cervus elaphus nelsoni) calves

Gonadotropin-releasing hormone is intermittently released from the hypothalamus in consistent patterns from before birth to final maturation of the hypothalamic-pituitary-gonadal axis at puberty. Disruption of this signaling via GnRH vaccination during the neonatal period can alter reproduction at maturity. The objective of this study was to investigate the long-term effects of GnRH-antibody exposure on reproductive maturation and function in elk calves passively exposed to high concentrations of GnRH antibodies immediately after birth. Fifteen elk calves (eight males and seven females) born to females treated with GnRH vaccine or sham vaccine during midgestation were divided into two groups based on the concentration of serum GnRH antibodies measured during the neonatal period. Those with robust (>15 pmol (125)I-GnRH bound per mL of serum) titers (N = 10; four females and six males) were designated as the exposed group, whereas those with undetectable titers (N = 5; three females and two males) were the unexposed group. Onset of puberty, reproductive development, and endocrine function in antibody-exposed and unexposed male and female elk calves were compared. Neonatal exposure to high concentrations of GnRH antibodies had no effect on body weight (P = 0.968), endocrine profiles (P > 0.05), or gametogenesis in either sex. Likewise, there were no differences between groups in gross or histologic structure of the hypothalamus, pituitary, testes, or ovaries. Pituitary stimulation with a GnRH analog before the second potential reproductive season induced substantial LH secretion in all experimental elk. All females became pregnant during their second reproductive season and all males exhibited similar mature secondary sexual characteristics. There were no differences between exposure groups in hypothalamic GnRH content (P = 0.979), pituitary gonadotropin content (P > 0.05) or gonadal structure. We concluded that suppressing GnRH signaling through immunoneutralization during the neonatal period likely does not alter long-term reproductive function in this species.

Tumor necrosis factor-alpha and acute-phase proteins in early pregnant ewes after challenge with peptidoglycan-polysaccharide

Bacterial infection shortly after mating interferes with establishment of pregnancy. Injection of peptidoglycan-polysaccharide (PG-PS), a component of gram-positive bacteria, into sheep on day 5 after mating reduces pregnancy rate. Experiments were designed to evaluate the acute-phase response (APR) in ewes to injection of PG-PS on day 5 after mating (day 0). Catheters were inserted into the jugular and posterior vena cava on day 4. On day 5, ewes were challenged with saline or 30 microg/kg body weight (BW) PG-PS (Exp 1) or 60 microg/kg BW PG-PS (Exp 2). Blood samples were collected every 15 min for 6 h (Exp 1) and every 15 min for 2 h, hourly for 12 h, and at 24, 36, and 48 h (Exp 2). Body temperature and clinical signs of infection were monitored in Exp 2. Plasma was assayed for concentrations of a pro-inflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha); 2 APR proteins, serum amyloid A (SAA) and haptoglobin (Hp); and progesterone (P(4)). Ewes injected with 60 microg/kg BW PG-PS exhibited fever, vaginal discharge, loss of appetite, and lethargy. After challenge with either 30 microg/kg or 60 microg/kg BW PG-PS, TNF-alpha increased in the posterior vena cava. Concentrations of SAA and Hp in the jugular increased after challenge with 60 microg/kg BW PG-PS. Only half (5/10) of the ewes treated with 60 microg/kg BW PG-PS had ultrasonically visible embryos, and none of them had functional corpora lutea (CL) (<1 ng/mL of P(4)) on day 21. On the other hand, 8/9 (88.9%) control ewes had visible embryos and all had functional CL on day 21. Using logistic regression, pregnancy on day 21 was predicted to depend on concentrations of TNF-alpha and Hp on day 5 and concentration of P(4) on day 14. In summary, injection of PG-PS on day 5 after mating resulted in fever; increased concentrations of TNF-alpha, Hp, and SAA on the day of and the day after the PG-PS challenge; and decreased concentrations of P(4) on days 14 and 21. These factors were related to failure to establish pregnancy.

Characterisation of lymphocyte subsets in the equine oviduct

REASONS FOR PERFORMING STUDY

The equine oviduct is the site of fertilisation and location of embryonic development during the first 5 or 6 days. It therefore has an important influence on mare fertility. Although histopathological changes have been described previously, there is limited information regarding lymphocyte subtypes present in the mucosa of the normal equine oviduct.

OBJECTIVES

To characterise the distribution of CD3+, CD4+, CD8+ and B lymphocytes in the equine oviduct from inseminated mares during oestrus and dioestrus, and from noninseminated mares during the immediate post ovulatory period.

METHODS

Oviductal tissues were collected from noninseminated mares at oestrus (> 30 mm follicle, n = 4), at Day 1 post ovulation (n = 3) and at dioestrus (Day 7 post ovulation; n = 4). Oviducts were also collected from inseminated mares at Days 1, 2, and 3 post ovulation (n = 4 for each period). Cross-sections of tissues from the ampullar-isthmic junction from each oviduct were snap frozen and cryostat sections stained by the immunoperoxidase technique with monoclonal antibodies directed against equine lymphocyte surface markers for B cells as well as CD3+, CD4+ and CD8+ cells.

RESULTS

In all oviductal sections examined, B cells were rare whereas T cells were relatively abundant. The predominant cell type found was the CD8+ phenotype, with a lesser number of CD4+ cells. Among mares, individual variation was large; therefore, although breeding status and stage of oestrous cycle appeared to alter lymphocyte populations, these differences were not significant.

CONCLUSIONS AND POTENTIAL RELEVANCE

A population of CD3+, CD4+ and CD8+ cells exists within the mucosal region of the equine oviduct. The density of these cells is similar to that described in the human oviduct. Their function is not currently known, but they may be involved with modulation of the maternal response to the presence of spermatozoa or the early conceptus within the equine oviduct. As our capacity to differentiate these cell types improves, along with the ability to identify the specific cytokines they produce, their functional significance will become more apparent.

Hypertension in response to autoantibodies to the angiotensin II type I receptor (AT1-AA) in pregnant rats: role of endothelin-1

Agonistic autoantibodies to the angiotensin II type I receptor (AT1-AA) and endothelin -1 (ET-1) are suggested to be important links between placental ischemia and hypertension during preeclampsia. Activation of the angiotensin II type 1 receptor (AT1R) increases endothelial cell production of ET-1; however, the importance of ET-1 in response to AT1-AA-mediated AT1 R activation during preeclampsia is unknown. Furthermore, the role of AT1-AA-mediated increases in blood pressure during pregnancy remains unclear. The objective of this study was to test the hypothesis that AT1-AA, increased to levels observed in preeclamptic women and placental ischemic rats, increases mean arterial pressure (MAP) by activation of the ET-1 system. Chronic infusion of purified rat AT1-AA into normal pregnant (NP) rats for 7 days increased AT1-AA from 0.68+/-0.5 to 10.88+/-1.1 chronotropic units (P<0.001). The increased AT1-AA increased MAP from 99+/-1 to 119+/-2 mm Hg (P<0.001). The hypertension was associated with significant increases in renal cortices (11-fold) and placental (4-fold) ET-1. To determine whether ET-1 mediates AT1-AA-induced hypertension, pregnant rats infused with AT1-AA and NP rats were treated with an ET(A) receptor antagonist. MAP was 100+/-1 mm Hg in AT1-AA+ET(A) antagonist-treated rats versus 98+/-2 mm Hg in ET(A) antagonist-treated rats. Collectively, these data support the hypothesis that one potential pathway whereby AT1-AAs increase blood pressure during pregnancy is by an ET-1-dependent mechanism.

Expression of essential B cell genes and immunoglobulin isotypes suggests active development and gene recombination during equine gestation

Many features of the equine immune system develop during fetal life, yet the naïve or immature immune state of the neonate renders the foal uniquely susceptible to particular pathogens. RT-PCR and immunohistochemical experiments investigated the progressive expression of developmental B cell markers and immunoglobulins in lymphoid tissues from equine fetus, pre-suckle neonate, foal, and adult horses. Serum IgM, IgG isotype, and IgA concentrations were also quantified in pre-suckle foals and adult horses. The expression of essential B cell genes suggests active development and gene recombination during equine gestation, including immunoglobulin isotype switching. The corresponding production of IgM and IgG proteins is detectable in a limited scale at birth. Although the equine neonate humoral response seems competent, B cell activation factors derived from antigen presenting cells and T cells may control critical developmental regulation and immunoglobulin production during the initial months of life.

Pregnancy alters the proliferation and apoptosis of mouse splenic erythroid lineage cells and leukocytes

Pregnancy induces dynamic changes in the maternal environment that include reversible modifications in response to systemic mediators and local signals. The spleen can be used to determine the effects of pregnancy on multiple cellular populations, including those of the erythroid lineage and the immune system. Current evidence suggests that the transient increase in the size of the spleen during pregnancy is due to the expansion of erythroid precursors. However, it is unclear what factors contribute to this increase. Moreover, the additional erythroid cells may compete with neighboring leukocytes for growth factors or space, and this may in turn alter the function of these populations. Therefore, we assessed proliferation and apoptosis throughout gestation using in vivo bromodeoxyuridine incorporation and the TUNEL assay, respectively. Here, we show that erythroid-lineage TER-119(+) cells expanded significantly in midgestation because of enhanced proliferation and diminished apoptosis. This correlated with increased expression of the erythropoietin receptor (Epor) and decreased expression of the death receptor Fas, respectively. Leukocytes demonstrated population-specific responses. Natural killer cells proliferated in early pregnancy. Both lymphocytes and CD11B(+) cells underwent enhanced proliferation during midgestation. In contrast, neutrophils exhibited augmented proliferation throughout pregnancy. These subset-specific alterations in proliferation and death in the spleen suggest that complex regulation of population dynamics exists during pregnancy.

Dehydroepiandrosterone and metformin modulate progesterone-induced blocking factor (PIBF), cyclooxygenase 2 (COX2) and cytokines in early pregnant mice

The present study examined the mechanism by which metformin (N,N'-dimethylbiguanide) prevents embryonic resorption induced in mice by dehydroepiandrosterone (DHEA). Treatment with DHEA (60mg/kg, s.c. 24 and 48h post-implantation) induces embryo resorption of early pregnant BALB/c mice while simultaneous treatment with metformin (240mg/kg, oral 24 and 48h post-implantation) prevents it. During pregnancy progesterone-induced blocking factor (PIBF) modulates prostaglandins (PGs) and cytokine production. These findings prompted us to investigate the effect of DHEA and metformin on both PIBF and cyclooxygenase 2 (COX2) expressions at the implantation sites, as well as cytokine production. PIBF and COX2 expression were detected by immunohistochemistry from DHEA and DHEA+ metformin treated 8 days-pregnant mice and serum cytokine levels of these animals were determined by ELISA. DHEA treatment both abolished PIBF expression and increased COX2 expression. Embryo resorption correlates with the lack of PIBF expression, diminished IL-6 levels and increased IL-2 concentration while metformin was able to reverse the effect of DHEA on both PIBF and COX2 expression and IL-6 levels. We concluded that hyperandrogenization induces embryo resorption in early pregnancy diminishing PIBF in implantation sites, having a pro-inflammatory effect. Metformin is able to prevent such effects.

Microenvironment of the feto–maternal interface protects the semiallogenic fetus through its immunomodulatory activity on dendritic cells

OBJECTIVE

To investigate the immunomodulatory activity of decidual culture supernatant on dendritic cell (DC) functions.

DESIGN

In vivo and in vitro experimental study using mice.

SETTING

Academic research laboratory.

ANIMAL(S)

C57BL/6-mated female Balb/c mice.

INTERVENTION(S)

Culture supernatants of decidual cells obtained from the uteri of allogenic pregnant mice (Balb/c x C57BL/6) were collected. Dendritic cells were purified from Balb/c mice spleens and pulsed with antigen during overnight culture. In some cultures, decidual supernatant was added at 5%, 10%, or 20% final concentration. Endometrial culture supernatant-treated DCs served as a control. Antigen-pulsed DCs were injected into the front footpads of syngeneic mice.

MAIN OUTCOME MEASURE(S)

Lymph nodes of primed mice were removed 5 days after DC injection. Antigen-specific proliferation and interleukin-10 and interferon gamma production by lymphocytes were measured by (3)H-Thymidine incorporation and ELISA, respectively.

RESULT(S)

The results showed that decidual culture supernatant markedly blocked in vivo antigen presentation by DCs and inhibited their capacity to induce interferon gamma (but not interleukin-10) production by primed lymphocytes.

CONCLUSION(S)

It seems that soluble factors produced by decidual cells are important mediators of immunoregulation at the feto-maternal interface, which provide the two fundamental requirements for protection of the semiallogenic fetus, namely immunologic tolerance and predominance of T helper 2 immunity, through modulation of DCs function.

Antigen-specific peripheral immune responses are unaltered during normal pregnancy in sheep

A shift in the balance of T(Helper) (T(H))1/T(H)2 cytokine production by maternal peripheral blood leukocytes is regarded as a common important feature of successful mammalian pregnancy. Although the phenomenon has been studied extensively in animals with invasive hemochorial placentae, the paradigm has not been studied in detail in species with less-invasive placentae, such as sheep that have a synepitheliochorial placenta. Sixteen sheep were immunised with the nominal antigen chicken egg albumin (Ova) and antigen-specific humoral and cellular responses were established in all sheep. The 16 sheep were synchronised, 11 were mated and successfully conceived, the remaining 5 served as non-pregnant controls. Peripheral blood mononuclear cells (PBMC) were isolated approximately every 2 weeks and restimulated in vitro with either Ova or the T cell mitogen concanavalin A (ConA), and cell proliferation and cytokine production measured. There were no detectable differences in antigen-driven PBMC proliferation, interferon-gamma (IFN-gamma), interleukin (IL)-4 or IL-10 production between pregnant and non-pregnant sheep. Also, there were no appreciable differences in ConA-induced IFN-gamma, IL-4 or IL-10 between the groups. These data suggest that a shift in T(H)1/T(H)2 cytokine production does not occur in pregnant sheep and indicate that further comparative reproductive immunology studies on species with non-invasive placentation will be informative of materno-fetal interactions and immune regulation during pregnancy.

Central and peripheral neuroimmune responses: hyporesponsiveness during pregnancy

There are periods in the life of a healthy animal (including humans) when the febrile response to an immune challenge is suppressed. One such period is during late pregnancy, particularly around the time of parturition. In the 30 or so years since this 'febrile hyporesponsiveness' was first noted, much work has been done to investigate the mechanisms and adaptive significance of this phenomenon. In this review we present some insight into how and why the body deliberately re-programmes itself to develop smaller fevers in response to an immune challenge and therefore to be potentially less successful at fighting infection.

Immunological mechanisms affecting angiogenesis and their relation to porcine pregnancy success

Prenatal mortality due to loss of lymphocyte-promoted endometrial angiogenesis is being investigated as a major cause of litter reductions during pregnancy in pigs. This review discusses immune mechanisms influencing porcine endometrial angiogenesis as well as additional signalling molecules that may play important roles in the compromise of peri-implantation and mid-gestation fetal pig survival. These include dendritic cells, signalling molecules such as toll-like receptors, chemokines and ficolins. Together these cells and molecules regulate immune responses and, ideally, protect the mother and prevent immune-based conceptus losses. Dendritic cells were recently shown to be angiogenic. Their tolerogenic role at the maternal-fetal interface coupled with the ability to secrete and respond to angiogenic factors suggests that dendritic cells are the key coordinators of angiogenesis at the porcine maternal-fetal interface. Chemokines coordinate the localization of immune effector and endothelial cells. The balance between pro-angiogenic and anti-angiogenic chemokines is addressed in relation to conceptus viability. Ficolins, components of the lectin-mediated complement activation pathway, are used for self/non-self recognition. Together, these components of the immune system could regulate lymphocyte- and non-lymphocyte-promoted endometrial angiogenesis to determine conceptus survival.

[Role of cytokines in implantation and maintenance of pregnancy]

The starting point of reproductive immunology is the understanding of the immunological mechanism for maintenance of pregnancy; why the fetus, which is a semi-allograft for the mother, is not rejected by the maternal immune system. Since Medawar pointed out this immunological contradiction in 1953, many investigators have addressed this question. As a result, we are coming to understand that not only a mere immunological tolerance but also immunotrophism, by which the immune system recognizes the fetal antigen actively, is important for the formation and maintenance of pregnancy. In addition, we are also coming to understand the importance of cytokines such as LIF and the cytokine environment of Th2 dominant. However, the cellular and microbiological mechanisms of these cytokines in the reproductive phenomenon are not well known. It is considered that the understanding of these mechanisms is useful for the clinical application to infertility or habitual abortion.

Immunosuppressive effect of pregnant mouse serum on allostimulatory activity of dendritic cells

In normal pregnancy, the maternal immune system is directed towards tolerance or suppression in order to prevent rejection of the semi-allogenic fetus. Antigen-presenting cells, especially dendritic cells (DCs), are key cells in initiation and regulation of immune responses. The presence of potent immunostimulatory DCs in the decidual tissue of pregnancy has been demonstrated. The aim of this study was to determine how allostimulatory activity of DCs could be affected during pregnancy. DCs were isolated from spleen of pregnant or non-pregnant Balb/c mice and co-cultured with allogenic T lymphocytes prepared from brachial lymph nodes of C57BL/6 mice. Some cultures of non-pregnant female DCs were treated by 2.5% serum obtained from pregnant mice at early, middle or late gestational periods, and were used in the same mixed lymphocyte reaction (MLR) settings. Cell proliferation was measured by 3H-thymidine incorporation, and cytokine production measured in supernatants of MLR cultures using ELISA. The effect of pregnant mouse serum on expression of DC surface markers was evaluated by flow cytometry. No significant difference was found between stimulatory potential of splenic DCs from pregnant and non-pregnant mice in induction of allogenic T cell proliferative response. Moreover, serum of early or late pregnancy did not have any effect on DC function in comparison with non-pregnant mouse serum, while mid-pregnancy serum significantly inhibited allostimulatory activity of DCs. IFNgamma production in co-culture of DCs treated with pregnant mouse serum was significantly lower than that of the control group; however, no significant difference in IL-10 production was observed. Treatment of DCs with pregnant mouse serum did not influence the percentage of cells expressing MHC-II, CD86, CD8alpha or CD11b. However, a marked reduction of the mean fluorescence intensity of MHC-II was observed. Collectively, our results concerning the diminished capacity of DCs to induce production of Th1 cytokines and allogenic T cell proliferation after treatment with pregnant mouse serum reveal a new way of immunologic tolerance against the semi-allogenic fetus.

Preferential distribution of NK cells into uteri of C57Bl/6J mice after adoptive transfer of lymphocytes

Circulating natural killer (NK) cells can migrate into target organs and possess tissue-associated differentiation and function under normal conditions. By adoptive transfer of spleen mononuclear cells (MNC) to C57Bl/6J mice at gestation day (gd) 6.5, it was found that 24h later both NK1.1(+) and CD3(+) cell populations migrated to the fetal-maternal interface. Although there was no statistical difference between the relative number of CFDA-SE(+) NK1.1(+) cells migrated into the decidua (1.13+/-0.18%) and that into liver (0.96+/-0.14%) or spleen (0.15+/-0.08%), it was noted that, by comparing the ratio of CFDA-SE(+) NK1.1(+) to CFDA-SE(+) CD3(+) cells in different tissues, peripheral NK1.1(+) but not CD3(+) cell populations, had preferentially migrated to decidua (1.61+/-0.08%) compared with that to liver (0.44+/-0.06%; p<0.05) or spleen (0.09+/-0.02%, p<0.05), respectively. This suggested that implantation sites were a primary site for NK cell homing when undergoing the decidualization reaction. But NK cell homeostasis can be altered when systemic Toll-like receptor (TLR) 3 signaling was evoked. In the case of poly I:C administration, adoptively transferred NK cells accumulated in liver, but not in uteri or spleen. It was concluded that there were different requirements for NK cell trafficking into given tissue niche during the pregnancy; mesometrial decidua render a privileged microenvironment for NK1.1(+) cell migration during the normal condition compared with liver or spleen. The constitution of the uterine NK cell pool was revealed not only in a spatiotemporal pattern but also in a stimuli-dependent manner.

Secreted phosphoprotein 1 (osteopontin) is expressed by stromal macrophages in cyclic and pregnant endometrium of mice, but is induced by estrogen in luminal epithelium during conceptus attachment for implantation

Secreted phosphoprotein 1 (SPP1, osteopontin) is the most highly upregulated extracellular matrix/adhesion molecule/cytokine in the receptive phase human uterus, and Spp1 null mice manifest decreased pregnancy rates during mid-gestation as compared with wild-type counterparts. We hypothesize that Spp1 is required for proliferation, migration, survival, adhesion, and remodeling of cells at the conceptus-maternal interface. Our objective was to define the temporal/spatial distribution and steroid regulation of Spp1 in mouse uterus during estrous cycle and early gestation. In situ hybridization localized Spp1 to luminal epithelium (LE) and immune cells. LE expression was prominent at proestrus, decreased by estrus, and was nearly undetectable at diestrus. During pregnancy, Spp1 mRNA was not detected in LE until day 4.5 (day 1 = vaginal plug). Spp1-expressing immune cells were scattered within the endometrial stroma throughout the estrous cycle and early pregnancy. Immunoreactive Spp1 was prominent at the apical LE surface by day 4.5 of pregnancy and Spp1 protein was also co-localized with subsets of CD45-positive (leukocytes) and F4/80-positive (macrophages) cells. In ovariectomized mice, estrogen, but not progesterone, induced Spp1 mRNA, whereas estrogen plus progesterone did not induce Spp1 in LE. These results establish that estrogen regulates Spp1 in mouse LE and are the first to identify macrophages that produce Spp1 within the peri-implantation endometrium of any species. We suggest that Spp1 at the apical surface of LE provides a mechanism to bridge conceptus to LE during implantation, and that Spp1-positive macrophages within the stroma may be involved in uterine remodeling for conceptus invasion.

The effect of skin allografting on the equine endometrial cup reaction

This research tested the hypothesis that immunological sensitization of mares by skin allografting, followed by the establishment of pregnancy using semen from the skin-graft donor, would give rise to secondary immune responses to the developing horse conceptus, resulting in an earlier demise of the fetally derived endometrial cups. Maiden mares received skin allografts from a stallion homozygous for Major Histocompatibility Complex (MHC) antigens and/or equivalent autografts and were subsequently mated to the skin-graft donor stallion during the next two breeding seasons. Mares that had been immunologically primed to the foreign MHC class I antigens of the skin-graft donor stallion developed strong secondary antibody responses early in their first pregnancies, whereas autografted mares made weak primary antibody responses in their first pregnancies and strong secondary responses in their second pregnancies. In contrast, histological examination of the endometrial cups after surgical pregnancy termination at Day 60 of gestation revealed no discernible differences between allografted and autografted mares, and there were no significant differences in the concentrations and/or duration of secretion of the endometrial cup-specific hormone, equine chorionic gonadotrophin (eCG), between allografted and autografted mares, nor in either group between first and second pregnancies. The vigorous antibody response observed in the pregnant allografted mares supported the first part of our hypothesis, providing evidence of systemic immunological priming. However, there was a lack of an equivalent heightened cellular response to the endometrial cups. These findings provided strong evidence for an asymmetric immune response to the conceptus, characterized by strong humoral immunity and a dampened cellular response.

Periparturient cortisol, acute phase cytokine, and acute phase protein profiles of gilts housed in groups or stalls during gestation

Use of gestation stalls in pork production remains a controversial topic in animal welfare. Immune status and measures are frequently used to assess stress levels and thus well-being of confined animals. The important welfare issue of close confinement among gestating gilts was tested by quantifying cortisol, acute phase cytokine, and acute phase protein pro-files before and after farrowing of gilts housed in 2 systems. Landrace x Yorkshire crossbred gilts housed in groups of 4 (group, n = 8) in pens (3.9 x 2.4 m with 4 individual feeding spaces, 9.36 m(2) total or 2.34 m(2)/gilt) were compared with gilts housed in standard industry stalls (stall, n = 16; 2.2 x 0.6 m, 1.32 m(2)/gilt). Floors were fully slatted, and a substrate was not provided for either system. Cortisol was determined from saliva on d 105 of gestation, 1 h after moving the gilts into farrowing stalls (d 111), and 24 h and 7 d after farrowing. Cortisol was greater (P = 0.04) for group gilts compared with stall gilts 1 h after moving them into farrowing stalls and 24 h after farrowing. Cortisol concentrations decreased (P = 0.001) over time. Leukocyte mRNA expression of IL-1, IL-1 receptor antagonist, and tumor necrosis factor-alpha was determined by quantitative, reverse transcription PCR on d 35, 63, and 91 of gestation and 72 h after farrowing. Cytokine mRNA expression of peripheral blood mononuclear cells did not differ between housing systems for IL-1, its receptor antagonist, or for tumor necrosis factor-alpha. Acute phase proteins, including fibrinogen, haptoglobin, and alpha(1)-acid glycoprotein were determined for plasma samples taken at d 35, 63, and 91 of gestation and 72 h and 14 d after farrowing. In contrast to cortisol, plasma fibrinogen concentrations increased (P < 0.005) over time. Haptoglobin did not differ between treatments (P > 0.10). Stall gilts tended to have greater (P = 0.07) plasma alpha(1)-acid glycoprotein concentrations than group animals at d 35 of gestation and d 14 after farrowing. These data showed a trend (P < 0.07) for alpha(1)-acid glycoprotein concentrations to return to baseline more quickly in group-housed gilts, which did not appear to be directly related to increased cortisol just before farrowing. In conclusion, few differences in the acute phase response were detected between housing systems, suggesting that the resting immunological responses are only mildly affected by gestation stalls.

Correlation between reproductive status and steady-state messenger ribonucleic acid levels of the Myxovirus resistance gene, MX2, in peripheral blood leukocytes of dairy heifers

The objectives of the current study were to evaluate the correlation between reproductive status and steady-state levels of Myxovirus resistance gene (MX2) mRNA in peripheral blood leukocytes (PBL) of dairy heifers and the reliability of using change in MX2 messenger RNA (mRNA) for identification of nonpregnant heifers 18 to 19 d after AI. Holstein heifers (n = 266), 13 +/- 1 mo of age, were assigned randomly to be inseminated (BRED; n = 214) or not (NONBRED; n = 52). Estrous cycles of all heifers were synchronized with an intravaginal insert containing progesterone for 7 d. At insert removal, heifers received an injection of PGF2alpha. Heifers in the BRED group were inseminated on detection of estrus or at a fixed time, 72 h after insert removal concomitant with a GnRH treatment. Heifers in the NONBRED group received an injection of GnRH 48 h after insert removal. Blood samples collected on d 0 (d of AI or estrus) and 18 were used to determine steady-state levels of MX2 mRNA. Samples collected on d 0, 7, 14, and 21 were analyzed for progesterone concentration. Pregnancy was determined retrospectively by progesterone concentration on d 21 and was diagnosed at 30 +/- 1 and 60 +/- 3 d after AI. The fold change in levels of MX2 mRNA from d 0 to 18 was greater for heifers classified and diagnosed as pregnant on d 21 (P < 0.05) and 30 +/- 1 (P < 0.05) and 60 +/- 3 (P < 0.05) d after AI compared with nonpregnant (bred but not pregnant) and NONBRED heifers. Heifers that experienced pregnancy loss from 21 to 30 +/- 1 (P = 0.11) or 21 to 60 +/- 3 (P = 0.08) d of gestation tended to have smaller fold increases in MX2 mRNA expression than those that maintained pregnancy. The sensitivity (range 57.1 to 65.6%) and negative predictive values (range 47.9 to 57.1%) of determining reproductive status on d 18 according to the change in the level of MX2 mRNA expression in PBL were low, and the correlation between diagnosis of pregnancy by fold change in MX2 mRNA expression and other methods was small (r = 0.20 to 0.36). The current study indicates that increased expression of MX2 mRNA in PBL is related to pregnancy approximately 21, 30, and 60 d after AI in dairy heifers and that losses that occurred later in pregnancy were associated with lower fold increases in MX2 mRNA. However, using the change in MX2 mRNA expression was not a reliable method for diagnosis of pregnancy at 18 d after AI because of the low sensitivity and negative predictive value.

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.

The influence of pre- and post-ovulatory insemination and early pregnancy on the infiltration by cells of the immune system in the sow oviduct

The aim of this study was to investigate the influence of pre- and post-ovulatory insemination and early pregnancy on the distribution of immune cells in the oviduct. Eighteen sows were pre-ovulatory and sixteen sows were post-ovulatory inseminated and slaughtered at different times, 5-6 h after insemination, 20-25 h and approximately 70 h after ovulation, day 11 and day 19. Immediately after slaughter, oviductal samples of three different segments (isthmus, ampulla and infundibulum) were fixed, embedded in plastic resin and stained with toluidine blue or cryofixed and stored in a freezer at -70 degrees C until analysed by immunohistochemistry (pre-ovulatory inseminated sows) with an avidin-biotin peroxidase method. Quantitative and qualitative examinations of oviductal epithelium and subepithelial connective tissue were performed by light microscopy. After pre- or post-ovulatory insemination, neutrophils were not observed in the oviductal epithelium from any of the segments or groups. The numbers of intraepithelial lymphocytes of all sows as well as CD2- and CD3-positive cells of the pre-ovulatory inseminated sows were higher in the infundibulum than in the other segments (p < or = 0.001). In the subepithelial connective tissue of the pre-ovulatory inseminated sows, significantly higher numbers of lymphocytes (p < or = 0.001) and plasma cells (p < or = 0.001) were found in infundibulum than in isthmus. Neutrophils were found mainly in infundibulum, the number approximately 40 h after pre-ovulatory insemination was significantly higher (p < or = 0.05) than in the other groups and segments. Significantly higher numbers of CD2 than CD3-positive cells were found for all groups and segments. In the subepithelial connective tissue of post-ovulatory inseminated sows, the numbers of lymphocytes was higher (p < or = 0.001) at day 19 than up to 50 h after insemination and lower (p < or = 0.001) in isthmus than in ampulla and infundibulum. Neutrophils were found in infundibulum in almost all groups and the number was significantly higher (p < or = 0.05) in the infundibulum up to 50 h after insemination than in other segments. In the oviductal epithelium, no influence of insemination was found on the presence of phagocytes, i.e. neutrophils and macrophages, but on lymphocytes. In the infundibular connective tissue, pre-ovulatory insemination had an effect on neutrophil distribution, indicating an active immune response to insemination in the upper segment. Post-ovulatory insemination changed the oviductal immune cell pattern.

Regulation of immune cells in the uterus during pregnancy in ruminants1

Pregnancy results in a change in number and function of immune cells in utero that potentially affects fetal survival and uterine defense mechanisms postpartum. These changes are driven by local signals from the conceptus as well as from hormonal changes mediated by the placenta or maternal system. In sheep, for example, macrophages accumulate in the uterine endometrium during pregnancy (Tekin and Hansen, 2004). Use of a unilaterally pregnant model, in which pregnancy is surgically confined to 1 uterine horn, has revealed that accumulation of macrophages is due to systemic signals (numbers of cells in the nonpregnant uterine horn of the unilaterally pregnant ewe higher than amounts in uteri of nonpregnant ewes) and locally produced signals (number of cells in the uterus of unilaterally ligated ewes higher in the pregnant horn than in the nonpregnant horn; Tekin and Hansen, 2004). Gamma-delta T cells also accumulate in uterine epithelium during pregnancy as a result of unidentified systemic signals (Lee et al., 1992; Majewski et al., 2001). These cells may participate in growth of the conceptus, immunosuppression, or placental detachment at parturition. One of the key regulators of uterine immune function is progesterone. In sheep, progesterone can block tissue graft rejection in utero when injected to achieve concentrations too low to directly inhibit lymphocyte proliferation (Majewski and Hansen, 2002; Padua et al., 2005). Progesterone probably inhibits uterine immune responses in sheep indirectly by inducing secretion of a member of the serine proteinase inhibitor family called uterine serpin from the endometrial epithelium. Uterine serpin can block lymphocyte proliferation in vitro in sheep (Peltier et al., 2000) and natural killer cell-mediated abortion in vivo in mice (Liu and Hansen, 1993). Uterine serpin is also present in cattle, goats, and pigs, but its role in immune function in these species has not been documented. The relevance of changes in uterine immune function to the reproductive and immune status of ruminants has not been fully established. There is evidence for immunological causes of pregnancy loss associated with cloned fetuses (Hill et al., 2002) and with mastitis (Hansen et al., 2004), but it is not known whether inappropriate recognition of alloantigens on the conceptus is an important cause of pregnancy loss. It is also possible that downregulation of uterine immune function during pregnancy can lead to a postpartum uterus with a compromised capacity for preventing establishment of infectious disease. Thus, optimal immune function in utero requires a balance between the need to maintain effective immune surveillance and effector mechanisms with the requirement that immunological responses leading to conceptus demise are minimized.

Effect of the level of iodine in the diet of pregnant ewes on the concentration of immunoglobulin G in the plasma of neonatal lambs following the consumption of colostrum

Excessive I in the diet of pregnant sheep can reduce the concentration of antibodies in the blood plasma of the lambs after they have consumed colostrum. Our aim was to determine the dose of dietary I that would avoid this effect, and to relate this to changes in the concentrations of hormones and metabolites in the lambs. Four groups of pregnant ewes received concentrate containing 5·5, 9·9, 14·8, and 21·0 mg I/kg DM, respectively. Hay and molasses (containing 0·16 and 0·29 mg I/kg DM, respectively) were available ad libitum. The lambs were prevented from suckling for the first 24 h of life and were fed a fixed quantity of artificial colostrum in four feeds. At 24 h, the average plasma concentrations of immunoglobulin G in the lambs were 6·08, 5·06, 3·18 and 3·10 g/l for the 5·5, 9·9, 14·8 and 21·0 mg/kg groups, respectively. Supplementation with I was associated with higher levels of tri-iodothyronine and thyroxine in the lambs at birth. There was no effect of treatment on the plasma concentrations of insulin, cortisol, glucose or NEFA in the lambs. The concentration of dietary I that had an effect on the immunoglobulin concentration in the lambs is marginally above the levels added to commercial concentrate feeds; we tentatively identify 9·9 mg I/kg DM (approximately 9 mg I/ewe per day) as the upper safe limit of I supplementation according to the criterion of the concentration of immunoglobulin G in the plasma of lambs at 24 h after birth.

Frequency and phenotype of EHV-1 specific, IFN-gamma synthesising lymphocytes in ponies: the effects of age, pregnancy and infection

Equine herpesvirus-1 (EHV-1) infects horses, causing acute respiratory disease, neurological signs, and is also a leading cause of abortion. Protection from EHV-1 infection and disease depends on both humoral (virus neutralising antibody) and cellular (mainly cytotoxic T lymphocytes, CTL) immune responses. CTL activity after EHV-1 infection has been extensively investigated and is closely associated with an alternative measure of cell mediated immunity (CMI), interferon-gamma (IFN-gamma) synthesis. This study investigates EHV-1-specific IFN-gamma synthesising cells in potentially immunocompromised horses; foals, pregnant mares and aged animals, after field or experimental infection with EHV-1. In foals and pregnant mares, the kinetics after experimental infection were similar and the phenotype of IFN-gamma+ synthesising cells after EHV-1 stimulation was mainly CD8alpha+. In contrast, in samples collected from primed healthy ponies exposed to EHV-1 several months previously or in old ponies (28 years old), the majority of EHV-1-specific IFN-gamma+ lymphocytes expressed a CD5+, CD8alpha- phenotype. This study highlights the complexity of the relationship between EHV-1, a common pathogen in horses, and the virus-specific cellular immune response as measured using IFN-gamma synthesis.

Characterization of the immune response in the placenta of cattle experimentally infected with Neospora caninum in early gestation

A serial examination of three groups of cattle infected intravenously (iv) (Group 1, n=8) or subcutaneously (sc) (Group 2, n=8) with live Neospora caninum tachyzoites or with VERO cells (Group 3, n=8) at 70 days' gestation was carried out and the nature of the inflammatory responses in the placenta and the presence of parasite antigen were analysed. Immune cells expressing CD3, CD4, CD8, gamma delta (gammadelta) T-cell receptors (TCR), CD79alpha cytoplasmic (cy) (B cells) and NKp46 [natural killer (NK) cells] antigens were identified immunohistochemically and cells expressing mRNA for interferon-gamma (IFN-gamma) were labelled by in-situ hybridization. Intravenous inoculation caused mortality in all fetuses from 28 days post-inoculation (dpi) onwards. Subcutaneous inoculation caused mortality in 50% of the animals by 28dpi. Pathological changes in the placenta consisted of necrosis of fetal placental villi, necrosis and inflammation in adjacent areas of the maternal septum and inflammation at the base of the maternal caruncle. The inflammatory infiltrate consisted mainly of CD3(+) lymphocytes, dominated by CD4(+) and gammadelta TCR(+) cells, with CD8(+) cells present to a lesser extent. The results from the control group indicated fewer NK cells than those occurring in the placenta of human beings or mice. Infiltration of CD4(+) cells and NKp46(+) cells was observed in the caruncular base and septa 14 days after infection, whereas infiltration of gammadelta TCR(+) cells was observed from 28 dpi onwards. To our knowledge this is the first report on the presence and distribution of NK cells in the bovine placenta. Maternal inflammatory cells expressing mRNA for IFN-gamma were identified in animals inoculated with parasites iv or sc at 14 and 28 dpi, respectively. In the sc-inoculated dams with live fetuses at 28, 42 and 56dpi, there was no evidence of parasite antigen, infiltration of immune cells or production of IFN-gamma, suggesting that the parasite had not reached the placenta. The exact cause of fetal death was not established. Tissue destruction by the parasite may have occurred; in addition, there may have been a T helper 1 (Th-1) immune response to the neospora infection at the materno-fetal interface, resulting in infiltrations of CD4T cells, gammadelta T cells and NK cells and the subsequent production of IFN-gamma. It is possible that a pro-inflammatory Th-1 response early in gestation protects the dam by eliminating the parasite; however, it may lead to destruction of the placental tissues themselves and thus be incompatible with fetal survival.

Dendritic Cells Therapy Confers a Protective Microenvironment in Murine Pregnancy

The fetal-placental unit is a semi-allograft and immunological recognition of pregnancy, together with the subsequent response of the maternal immune system, is necessary for a successful pregnancy. Dendritic cells (DC) show a biological plasticity that confers them special characteristics regulating both immunity and tolerance. Therapy employing DC proved to diminish the abortion in the DBA/2J-mated CBA/J females; however, the underlying mechanisms remain unknown. Here, we evaluated whether DC therapy influences the presence of immunoregulatory populations of cells at the fetal-maternal interface. To address this hypothesis, we analysed the pregnancy-protective CD8, gammadelta cell populations as well as transforming growth factor (TGF)-beta1 and progesterone-induced blocking factor (PIBF) expression at the fetal-maternal interface from abortion-prone female mice that had previously received adoptive transfer of syngeneic DC. Syngeneic DC therapy induced an increase in the number of CD8 and gammadelta cells. Additionally, an upregulation of TGF-beta1 and PIBF expression could be detected after DC transfer. We suggest that DC therapy differentially upregulates a regulatory/protective population of cells at the fetal-maternal interface. It is reasonable to assure that this mechanism would be responsible for the lower abortion rate.

Regulatory T cells in pregnancy

Tolerance mechanisms are responsible for the survival of the fetus within the maternal uterus without being attacked by the cells of the maternal immune system despite their direct contact. Regulatory T cells (Treg) were claimed to be important players in the tolerance towards the fetus bearing alloantigens. Recent evidence confirmed an augmentation in the number of Treg during pregnancy and, most importantly, diminished numbers of Treg were associated with immunological rejection of the fetus. This could be prevented by adoptively transferring CD4(+)/CD25(+) Treg cells from normal pregnant mice into abortion-prone animals. Treg prevented abortion while creating a transient tolerant microenvironment characterized by high levels of TGF-beta, LIF, and HO-1. Downregulated levels of Treg were accordingly also reported during human miscarriage. Furthermore, we have evidence suggesting that, to be protective, Treg need to be activated by male antigens during pregnancy.

Effects of modified-live bovine viral diarrhea virus vaccines containing either type 1 or types 1 and 2 BVDV on heifers and their offspring after challenge with noncytopathic type 2 BVDV during gestation

OBJECTIVE

To compare the efficacy of modified-live virus (MLV) vaccines containing either type 1 bovine viral diarrhea virus (BVDV) or types 1 and 2 BVDV in protecting heifers and their offspring against infection associated with heterologous noncytopathic type 2 BVDV challenge during gestation.

DESIGN

Randomized controlled study.

ANIMALS

160 heifers and their offspring.

PROCEDURES

After inoculation with a placebo vaccine, 1 or 2 doses of an MLV vaccine containing type 1 BVDV, or 1 dose of an MLV vaccine containing both types 1 and 2 BVDV, heifers were bred naturally and challenge exposed with a type 2 BVDV field isolate between 62 and 104 days of gestation. Pregnancies were monitored; after parturition, virus isolation and immunohistochemical analyses of ear-notch specimens were used to determine whether calves were persistently infected. Blood samples were collected at intervals from heifers for serologic evaluation and virus isolation.

RESULTS

Persistent infection was detected in 18 of 19 calves from heifers in the control group and in 6 of 18 calves and 7 of 19 calves from heifers that received 1 or 2 doses of the type 1 BVDV vaccine, respectively. None of the 18 calves from heifers that received the type 1-type 2 BVDV vaccine were persistently infected.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the incidence of persistent BVDV infection among offspring from dams inoculated with 1 dose of the MLV vaccine containing types 1 and 2 BVDV was decreased, compared with 1 or 2 doses of the MLV vaccine containing only type 1 BVDV.

Immune activation during pregnancy in mice leads to dopaminergic hyperfunction and cognitive impairment in the offspring: a neurodevelopmental animal model of schizophrenia

BACKGROUND

Maternal viral infection is associated with increased risk for schizophrenia. It is hypothesized that the maternal immune response to viruses may influence fetal brain development and lead to schizophrenia.

METHODS

To mimic a viral infection, the synthetic double strand RNA polyriboinosinic-polyribocytidilic acid (poly I:C) was administered into pregnant mice. Behavioral evaluations (thigmotaxis, methamphetamine [MAP]-induced hyperactivity, novel-object recognition test [NORT]), sensorimotor gating (prepulse inhibition [PPI]), and biochemical evaluation of the dopaminergic function of the offspring of phosphate-buffered saline (PBS)-treated dams (PBS-mice) and that of poly I:C-treated dams (poly I:C-mice) were examined.

RESULTS

In juveniles, no difference was found between the poly I:C-mice and PBS-mice. However, in adults, the poly I:C-mice exhibited attenuated thigmotaxis, greater response in MAP-induced (2 mg/kg) hyperlocomotion, deficits in PPI, and cognitive impairment in NORT compared with the PBS-mice. Cognitive impairment in the adult poly I:C-mice could be improved by subchronic administration of clozapine (5.0 mg/kg) but not haloperidol (.1 mg/kg). Increased dopamine (DA) turnover and decreased receptor binding of D2-like receptors, but not D1-like receptors, in the striatum were found in adult poly I:C-mice.

CONCLUSIONS

Prenatal poly I:C administration causes maturation-dependent increased subcortical DA function and cognitive impairment in the offspring, indicating a neurodevelopmental animal model of schizophrenia.

Suppressed oxytocin neuron responses to immune challenge in late pregnant rats: a role for endogenous opioids

Cytokine challenge (mimicking infection) with systemic interleukin-1beta (IL-1beta) stimulates oxytocin neurons via a noradrenergic brainstem pathway similar to that involved in parturition. As the responses of oxytocin neurons to several stimuli are reduced in late pregnancy, we have investigated whether responses to IL-1beta are also suppressed. In virgin Sprague-Dawley rats, IL-1beta (500 ng/kg i.v.) rapidly increased oxytocin secretion (3.2-fold), via a central action as the firing rate of oxytocin neurons in the supraoptic nucleus was increased. In contrast, IL-1beta had no significant effect on the electrical or secretory activity of oxytocin neurons in late pregnant rats. In pregnancy activation of a central inhibitory opioid mechanism restrains oxytocin neuron responses to various stimuli. Accordingly, we tested the effects of the opioid antagonist, naloxone, on oxytocin neuron responses to IL-1beta in pregnancy. Naloxone (5 mg/kg i.v.) did not affect the oxytocin secretory response to IL-1beta in virgin rats, whereas in late pregnant rats naloxone revealed a greater oxytocin secretory response to IL-1beta (3.5-fold) than in virgin rats. In virgin rats, naloxone decreased oxytocin neuron firing rate after IL-1beta, however, in pregnant rats naloxone increased the firing rate response to IL-1beta to the level seen in virgin rats. Thus, systemic IL-1beta acts centrally to increase oxytocin secretion. In pregnancy this response is suppressed by endogenous opioids, thus preserving neurohypophysial oxytocin stores for parturition and minimizing the risk of preterm labour. The exaggerated oxytocin secretory response to IL-1beta in pregnancy after naloxone reflects increased oxytocin stores and/or increased efficiency of excitation-secretion coupling at the posterior pituitary.

Placental and fetal membrane Nephrin and Neph1 gene expression: response to inflammation

OBJECTIVE

Fetal and amniotic fluid (AF) proteins (eg, alpha fetoprotein [AFP]) are measurable in the maternal circulation. Elevated maternal serum AFP levels indicate a risk for fetal anomalies or for obstetrical complications that are often associated with inflammation (eg, preterm labor). However, little is known of the mechanism of protein exchange between the fetus, AF, and maternal circulation. Nephrin and Neph1 are cell membrane proteins that restrict glomerular protein filtration and which are differentially expressed with renal inflammation. We sought to investigate whether nephrin and Neph1 were expressed in placenta and fetal membranes, and whether inflammation modified the expression.

METHODS

Pregnant rats at 18 days' gestation were injected with lipopolysacchride (LPS) or control saline intraperitoneally (IP) and killed at 1, 6, and 12 hours after injection. Placenta and fetal membranes were obtained and real-time polymerase chain reaction (PCR) performed for determination of nephrin and Neph1 levels.

RESULTS

Nephrin and Neph1 were expressed in both placenta and fetal membranes. Following maternal LPS administration, nephrin mRNA significantly increased in the membranes (0.22 +/- 0.02 to 0.51 +/- 0.050, P <.05), while Neph1 expression significantly declined in the placenta (0.19 +/- 0.05 to 0.10 +/- 0.01, P <.05).

CONCLUSION

Fetal membranes and placenta of the rat express mRNA for the protein barriers nephrin and Neph 1, suggesting a role in the regulation of protein transfer from the fetus to mother. Under basal conditions, AF AFP transfer across fetal membranes may account for maternal serum AFP levels, whereas gestational inflammatory conditions (eg, preterm labor, threatened abortion) may augment AFP transfer across the placenta.

Regulatory T cells induce a privileged tolerant microenvironment at the fetal-maternal interface

The mechanisms underlying immune tolerance during pregnancy are poorly understood. In this regard, Treg seem to play an important role in mediating maternal tolerance to the fetus. We proposed a crucial role of T regulatory cells (Treg) in avoiding immunological rejection of the fetus after observing diminished number and function of Treg in abortion-prone mice. We further confirmed the protective role of Treg during pregnancy by transferring pregnancy-induced Treg into abortion-prone mice, which prevented rejection. Here, we analyzed the mechanisms involved in Treg-mediated protection. As expected, Treg therapy prevented abortion, while expanding the peripheral and thymic Treg population. Surprisingly, the decidual levels of the Th1 cytokines IFN-gamma and TNF-alpha were not diminished after therapy. Interestingly, the mRNA levels of leukemia inhibitory factor, TGF-beta and heme oxygenase-1 at the fetal-maternal interface were dramatically up-regulated after Treg transfer, while the levels of indolamine 2,3-dioxygenase remained unchanged. Our data suggest that Treg treatment can not prevent T cell infiltration or high Th1 levels but is able to create a privileged tolerant microenvironment at the fetal-maternal interface, further shedding light onto the molecular mechanisms involved in pregnancy tolerance.

A Screening for the Occurrence of Autoreactive Antibodies in Sera of Pregnant and Non-pregnant Bitches

Sera of healthy pregnant (group I, n = 11) and non-pregnant (group II, n = 11) bitches were screened for autoantibodies (AAb). In both groups, blood samples were drawn every fifth day between days 5 and 55 after mating. Serum was analysed via indirect immunofluorescence (IIF) with the Canine ANA HEp-2 Screening Kit. In all animals, anticytoplasmic AAb were detected. Utilizing primate-heart substrate slides AAb against contractile proteins of the cytoplasm could be observed. The predominating fluorescence pattern in pregnant animals resembled above all desmin, which was proven via Western blot. The sera were then pre-incubated with tropomyosin, actin, vimentin, vinculin and keratin solutions, and assessed on HEp-2 slides and on human and canine fibroblasts as well. The latter substrate was used to verify whether the detected Ab were in fact AAb. Utilizing tropomyosin, revealed elimination of the cytoplasmic fluorescences on all three substrates. It is therefore assumed, that in sera of healthy dogs, AAb against contractile structure proteins of the cytoplasm are present regularly. The majority of pregnant bitches presented with higher end-point titres (EPT), than to be found in non-pregnant dogs. AAb against desmin played the key role in those patterns. In addition, sera were screened for thyroid specific AAb, namely thyroglobulin, thyroid peroxidase (TPO), T3 and T4, and for AAb against insulin by ELISA or Western blot (TPO). Only in two of the pregnant bitches a weak positive reaction (1:100) for T3-AAb was detected.

Attenuation of fever at near term: is interleukin-6-STAT3 signalling altered?

Pregnant rats in late gestation show a reduced fever response after stimulation with lipopolysaccharide (LPS). This can result from either an increased action of endogenous antipyretics or a reduction in the production or action of endogenous pyrogens. Nonpregnant rats given LPS release interleukin (IL)-6, which causes nuclear translocation of the signal transducer and activator of transcription 3 (STAT3) in the vascular organ of the lamina terminalis (OVLT), followed by a significant increase in core body temperature. The present study investigated whether the reduced fever response in near-term pregnant rats is associated with a reduced nuclear STAT3 response. Rats at gestation day 15 (G15), gestation day 21 (G21, near term) and at lactation day 5 (L5) were injected with LPS (50 microg/kg, i.p.) or vehicle. Only near-term pregnant rats responded with an attenuated body temperature during the fever response. Immunohistological analysis indicated no significant difference in nuclear STAT3 in the OVLT of the different animal groups 2 h after LPS. Measurement of total and phosphorylated STAT3 protein in the OVLT with semiquantitative western blot revealed no significant differences of this protein among these immune challenged animal groups. IL-6 concentrations were also similar at G15, G21 and L5 2 h after injection of LPS. These results lead to the conclusion that the attenuation of the fever response at near-term pregnancy is not associated with a reduced amount of nuclear STAT3 in the OVLT, indicating a maintained IL-6-STAT3 signalling pathway in the OVLT.

Fetal protection following exposure to calves persistently infected with bovine viral diarrhea virus type 2 sixteen months after primary vaccination of the dams

This study demonstrated that the bovine viral diarrhea virus (BVDV; types 1 and 2) fractions of a multivalent vaccine protected pregnant heifers and their fetuses at 149 to 217 days of gestation against exposure to calves persistently infected with BVDV type 2a. Eighty percent (eight of 10) of the control heifers were viremic at least 1 day following challenge, whereas all (20 of 20) BVDV-vaccinated heifers were virus isolation-negative on all postchallenge assessment days. Ninety percent (nine of 10) of the calves born to control heifers but only 5% (one of 20) of calves born to BVDV-vaccinated heifers seroconverted to BVDV type 2 before ingesting colostrum. One calf born to a control heifer was persistently infected. No calves from BVDV-vaccinated heifers were persistently infected.

Influence of sex steroids on the viability and CD11b, CD18 and CD47 expression of blood neutrophils from dairy cows in the last month of gestation

In the period around parturition, cows experience an increased susceptibility for the development of Escherichia coli mastitis. This increased susceptibility has been correlated with a decreased functionality of neutrophils. In the current study, it is suggested that the decreased neutrophil functionality may be induced by the extensive alterations in sex steroid levels occurring around parturition. It was first hypothesized that 17beta-estradiol and progesterone influence the viability, apoptosis and necrosis of blood neutrophils from cows in their last month of gestation. Subsequently, it was hypothesized that 17beta-estradiol modulates the expression of CD11b, CD18 or CD47 thereby explaining its influence on the migration of bovine neutrophils. Neither 17beta-estradiol nor progesterone significantly influenced viability, apoptosis or necrosis in spontaneous apoptosis conditions. However, when apoptosis was induced with TNF-alpha and gliotoxin, progesterone exerted a survival effect (P<0.05). In addition, 17beta-estradiol treatment of bovine blood neutrophils significantly decreased the expression of CD47 (P<0.05) but not of CD11b or CD18. It can be concluded that 17beta-estradiol and progesterone do not affect spontaneous apoptosis of bovine blood neutrophils while a survival effect was observed for progesterone on induced neutrophils apoptosis. Moreover, our results concerning the influence of 17beta-estradiol on the CD11b, CD18 and CD47 expression extend previous demonstrations of the suppressive effect of 17beta-estradiol on neutrophils migration and indicate that the altered expression of CD47 may contribute to this phenomenon.

Enhanced expressions of endometrial tumour necrosis factor alpha and its receptors during early pregnancy in bonnet monkeys

Tumour necrosis factor alpha (TNF-alpha), a pro-inflammatory cytokine may play an active role in stimulating inflammatory reactions during pregnancy. However, the expression of endometrial TNF-alpha has not been investigated especially during early pregnancy, a phenomenon invariably accompanied by inflammatory reaction. In the present study, the endometrial expressions of TNF-alpha and its receptors (TNFR1 and TNFR2) during early pregnancy, when the embryo lies free in the zona hatched state in the uterine lumen, were analyzed by immunohistochemistry. The endometrial expressions of TNF-alpha, TNFR1 and TNFR2 were found to be significantly up-regulated (p < 0.05) in the glandular epithelium on day 6 post-ovulation in pregnant animals. The alteration in the expression of these molecules may contribute to the induction of local inflammatory reactions during implantation.

Blockade of CD80 and CD86 at the time of implantation inhibits maternal rejection to the allogeneic fetus in abortion-prone matings

CD28/CTLA-4 interactions with their specific B7-ligands (CD80 and CD86) play a decisive role in antigenic and allogenic responses. Recently, experimental transplant studies demonstrated that donor-specific tolerance was achieved by blocking these interactions. However, the role of blockade of CD28/B7 costimulatory pathway in the maintenance of materno-fetal tolerance has received little attention. In the present study, abortion-prone CBA/J females mated with DBA/2 males were administered with anti-CD80 and anti-CD86 monoclonal antibodies (mAbs) on day 4 of gestation (time of murine implantation). We demonstrated that the combined use of anti-CD80 and anti-CD86 mAbs induced maternal tolerance to the fetus in the abortion-prone CBA/J mice, and displayed expansion of the maternal CD4(+)CD25+ regulatory T cell population and up-regulated expression of CTLA-4, suggesting an active mechanism of regulatory T cells in suppressing maternal rejection to the fetus. In addition, the anti-CD80/86 mAbs treatment enhanced Th2 and reduced Th1 cytokine production in mice, implying that the development of Th2 cells might contribute to maternal tolerance to her fetus. Together, these findings indicated that blocking CD80 and CD86 enhanced maternal tolerance to her fetus in mice by increasing regulatory T cell function and skewing toward a Th2 response. Our data might provide an enhanced understanding of the maternal-fetal immune relationship and be helpful in clinical trials for immunotherapy of recurrent spontaneous abortion.

Macrophage density in the pregnant rat uterine cervix is modulated by mast cell degranulation

The uterine cervix at term undergoes histomorphological changes that resemble an inflammatory process. The aim of this study was to better characterize these changes, describing the temporal and spatial pattern of macrophages and mast cells (MC) distribution in the uterine cervix and assessing whether both cells exert a coordinated action on angiogenesis. Macrophages and MC were identified by immunohistochemistry in cervical tissue from cycling, pregnant and postpartum rats. In order to inhibit MC degranulation, pregnant rats were injected with disodium cromoglycate. The expression of vascular endothelial growth factor (VEGF) by macrophages was also evaluated. Results showed that macrophage density increased towards parturition and declined at postpartum, whereas MC density showed an inverse pattern. Interestingly, disodium cromoglycate-treated rats showed an increased number of macrophages. VEGF expression in macrophages was detected neither in control nor in treated animals; however, a coordinated action between MC and macrophages on angiogenesis could not be excluded. The present study provides a detailed mapping of macrophage and MC densities and distribution in the rat uterine cervix. Moreover, an association between macrophages and MC along pregnancy is shown, and evidence that macrophage density in the rat cervix is modulated by MC degranulation is presented.

Immunophenotypical Characterization of Lymphocyte Subpopulations of the Uterus of Non-pregnant and Pregnant Goats

The increased susceptibility during pregnancy to certain pathogens that cause abortions may be related to changes in the distribution and phenotype of lymphocyte subpopulations in the uterus. Histological, electron microscopic and immunocytochemical techniques were used in this study to examine whether such variations occur in different stages of the reproductive cycle of goats. The study of non-pregnant goats showed that most uterine lymphocytes were T cells and displayed both an intraepithelial and stromal distribution. CD8+ T lymphocytes were more numerous than CD4+ T lymphocytes. In the endometrial epithelium two lymphocyte subpopulations were observed: non-granulated CD2+ CD8+ T lymphocytes and granulated CD2+ CD8- T lymphocytes. During gestation, no lymphocytes were observed in the placentomal area, while a decreased number of T lymphocyte subpopulations were found in the inter-placentomal area. In the inter-caruncular epithelium, non-granulated CD2+ CD8+ T lymphocytes disappeared, whereas the granulated CD2+ CD8- T lymphocyte subpopulations increased their number and changed their morphology.

Species differences in the effect of pregnancy on lymphocyte cytokine production between human and rat

In the present study, we evaluated whether lymphocyte cytokine production during human and rat pregnancy shifts toward T helper cell type 2 (Th2) cytokine production. Therefore, blood samples were taken during the follicular and luteal phase and during pregnancy in rats and humans. Whole blood was ex vivo-stimulated with phorbol 12-myristate 13-acetate and calcium ionophore and intracellular interferon-gamma (IFN-gamma) and interleukin (IL)-4 production, and the percentage of cells in the various lymphocyte populations was measured using flow cytometry. Rats and humans adapted their immune responses to pregnancy but have different strategies: During human pregnancy, the percentage of lymphocytes producing IFN-gamma was decreased, and the percentage IL-4-producing lymphocytes was not affected. The rat adapts its immune response to pregnancy by decreasing the total number of the various lymphocyte populations, and the percentage of IFN-gamma- or IL-4-producing lymphocytes was not affected or increased (% IFN-gamma-producing cytotoxic lymphocytes). It is speculated that during rat pregnancy, there is no need to decrease the number of IFN-gamma-producing lymphocytes, as in nonpregnant rats, the total number of IFN-gamma-producing lymphocytes after stimulation is relatively low, and there is no necessity for a further decrease. In nonpregnant humans, the percentage IFN-gamma-producing lymphocytes is much higher and probably dangerous for pregnancy, and therefore, this percentage needs to decrease during pregnancy. In conclusion, although the data from humans concur with the Th1/Th2 paradigm, the data from rats do not concur with this paradigm. The present studies therefore challenge the classical Th1/Th2 paradigm during pregnancy.

Effects of feeding intensity during the dry period on leukocyte and lymphocyte sub-populations, neutrophil function and health in periparturient dairy cows

The objective of this investigation was to study (1) the numbers of leukocytes, (2) the proportions of lymphocytes expressing CD4, CD8, WC1, B or IL2R and (3) neutrophil phagocytosis and oxidative burst activity in blood around parturition in three groups of dairy cows fed different levels of a total mixed ration during the last eight weeks before calving. All cows were fed ad libitum during the first eight weeks of lactation. Serum concentration of the acute phase protein serum amyloid A (SAA), the milk somatic cell count (SCC) and disease incidence were also recorded. Special emphasis was given to the weeks just before and just after calving as dairy cows are known to be immune suppressed during this period. Dry period diet had only minor effects on leukocyte numbers, and did not influence neutrophil phagocytosis and oxidative burst. In addition, no effect was observed on disease incidence or SAA concentrations. However, an increase in the proportion of B-lymphocytes and a decrease in the proportion of WC1+ T lymphocytes were observed after calving in cows fed high or low energy rations during the dry period, but not in cows fed a medium energy ration. The weeks just before and after parturition were characterised by neutrophilia, eosinopenia, lymphopenia and monocytosis, but time had no effect on neutrophil phagocytosis and oxidative burst. The proportions of CD4+, CD8+, B+ and IL-2R+ lymphocytes increased in early lactation relative to the mid dry period. In addition, the concentration of SAA increased dramatically at calving. The results emphasise the need for more studies to clarify the complex interactions between nutrition and immunity during the peripartum period in dairy cattle.

Phenotypic changes associated with advancing gestation in maternal and fetal baboon lymphocytes

Baboons are very similar to humans in ontogeny, reproductive physiology, and placentation, and thus serve as an excellent nonhuman primate model for use in both normative and perturbation studies of pregnancy that cannot be performed on pregnant women. However, little is known about the changes induced by normal pregnancy in the maternal and fetal baboon in lymphocyte subset composition, and lymphocyte activation and proliferation. We performed multicolor flow cytometry analysis of peripheral venous blood samples obtained from pregnant baboons at mid-gestation (0.5 G), and from matched fetal heart (FH) and umbilical cord (UC) blood at the end of gestation (0.95 G). Compared with their mothers at 0.95 G, fetal lymphocytes had higher percentages of B and CD4+ T cells, and lower numbers of NK and CD8+ T cells. When comparing pregnant baboons at 0.5 and 0.95 G, we also found that pregnancy induces immune stimulation, measured as higher activation without proliferation of CD8+ T and NK cells in the maternal circulation. Our study adds new data to support the notion of pregnancy-induced immune activation and strengthens the value of the baboon as a nonhuman primate model for studies pertinent to human reproductive physiology, pathology, and vaccination.