Effect of progesterone on the vaccination and immune response against Chlamydia abortus in sheep

Chlamydia abortus produces ovine enzootic abortion (OEA). Symptoms are not observed until the organism colonises the placenta, eventually causing abortion. Infected animals become carriers and will shed the organism in the following oestruses. This process suggests that sex hormones might play an important role in the physiopathology of OEA, affecting the success of chlamydial clearance and also jeopardising the effectiveness of vaccination. However, the mechanisms through which sex hormones are involved in chlamydial pathogenicity remain unclear. The aim of this study, therefore, was to determine the effect of progesterone on the immune response against C. abortus and on the protection conferred by an experimental inactivated vaccine in sheep. Eighteen sheep were ovariectomised and divided into four groups: vaccinated and progesterone-treated (V-PG), vaccinated and non-treated (V-NT), non-vaccinated and non-treated (NV-NT) and non-vaccinated and progesterone-treated sheep (NV-PG). Animals from both PG groups were treated with commercial medroxyprogesterone acetate impregnated intravaginal sponges before and during the vaccination (V-PG) or just before challenge (NV-PG). The animals from both V groups were subcutaneously immunised with an experimental inactivated vaccine, which was seen to confer high protection in previous studies. All sheep were challenged intratracheally with C. abortus strain AB7 and were sacrificed on day 8 post-infection. Morbidity was measured as the variation in rectal temperature and samples of sera were collected for antibody and cytokine (IFN-γ and IL-10) analysis by commercial ELISA. In addition, lung and lymph node samples were collected for chlamydial detection by qPCR and for histopathological and immunohistochemical analyses. Sheep from the V-PG group showed less severe or no lesions and lower morbidity than the other groups. They also had the highest abundance of regulatory T-cells. The sheep from V-NT also manifested high antibody levels against C. abortus and less severe lesions than those observed in non-vaccinated sheep, which showed high morbidity, low antibody levels and severe lesions, especially in NV-NT. These results confirm the effectiveness of the experimental vaccine employed and suggest that progesterone could enhance the effect.

Progesterone suppresses the lipopolysaccharide-induced pro-inflammatory response in primary mononuclear cells isolated from human placental blood

Progesterone is an essential hormone that induces deep immune adaptations favoring pregnancy maintenance. We aimed at evaluating the effects of progesterone on the synthesis of pro- and anti-inflammatory cytokines by mononuclear cells isolated from human placental blood stimulated with lipopolysaccharide, emulating an infection-inflammation environment. Mononuclear cells isolated form human placental blood were obtained from nine women undergoing elective cesarean delivery at term (not in labor), isolated by density gradient sedimentation, cultured and co-stimulated with lipopolysaccharide (500 ng/ml) from Escherichia coli in the presence or not of progesterone (0.01, 0.1, or 1.0 µM) for 24 h. Culture supernatants were assayed for pro-inflammatory (IL-1β, TNFα, IL-6), anti-inflammatory (IL-10) cytokines, chemokines (IL-8, MIP-1α) and total MMP-9 by ELISA. In comparison with basal conditions, lipopolysaccharide treatment induced IL-1β, TNFα, IL-6, IL-8, MIP-1α, and MMP-9 synthesis. lipopolysaccharide co-treatment with progesterone significantly decreased the bacterial endotoxin-induced IL-1β, TNF-α, IL-6, IL-8, and MIP-1α secretion. In contrast, co-treatment with progesterone increased the level of IL-10 secreted to the culture medium. The present results support the concept that progesterone can modulate--partially--the inflammatory response of professional immune cells isolated from placental blood. Therefore, progesterone might be part of the natural compensatory mechanism that limits the cytotoxic effects associated with an intrauterine infection process during gestation.

[Chronic inflammatory and autoimmune mediated dermatoses during pregnancy. Course and prognosis for mother and child]

Chronic inflammatory dermatoses during pregnancy can take varying courses in mother and child. The dominant Th2-response characteristic for pregnancy may explain why atopic eczema or lupus erythematosus may deteriorate while psoriasis vulgaris may improve. In contrast, impetigo herpetiformis frequently shows a severe course. Lupus erythematosus and other autoantibody-triggered dermatoses like pemphigus vulgaris pose an increased risk for the child because of placental transfer of autoantibodies with specific skin changes or systemic manifestations of the disease as well as placental insufficiency, growth retardation and premature birth. Such risks are not associated with linear IgA dermatosis. A severe pityriasis rosea during the first 20 weeks of pregnancy may lead to an increased risk of abortion or premature delivery. Early diagnosis and individually adjusted therapy of skin diseases is mandatory to avoid any risk for mother or child.

Uterine natural killer cells: a specialized differentiation regulated by ovarian hormones

In adult females of many species, a transient population of natural killer (NK) cells appears in cycles within the uterine endometrium (lining). Appearance of these lymphocytes coincides with specific phases of the ovarian hormone cycle and/or early pregnancy. Studies in rodents, women, and pigs dominate the literature and suggest the uterine (u)NK cells are an activated subset sharing many but not all features with circulating or lymphoid organ-residing NK cells. During successful murine pregnancy, uNK cells appear to regulate initiation of structural changes in the feed arterial systems that support maternal endometrial tissue at sites of implantation and subsequent placental development. These changes, which reverse after pregnancy, create a higher volume arterial bed with flaccid vessels unresponsive to vasoactive compounds. These unique pregnancy-associated arterial changes elevate the volume of low-pressure, nutrient-rich, maternal arterial blood available to conceptuses. Regulation of the differentiation, activation, and functions of uNK cells is only partially known, and there is lively debate regarding whether and how uNK cells participate in infertility or spontaneous abortion. This review highlights the biology of uNK cells during successful pregnancy.

Essential Role for IL-10 in Resistance to Lipopolysaccharide-Induced Preterm Labor in Mice

IL-10 is highly expressed in the uterus and placenta and is implicated in controlling inflammation-induced pathologies of pregnancy. To investigate the role of IL-10 in regulating preterm labor, the response of IL-10 null mutant mice to low-dose LPS in late gestation was evaluated. When IL-10 null mutant C57BL/6 (IL-10(-/-)) and control (IL-10(+/+)) mice were administered LPS on day 17 of pregnancy, the dose of LPS required to elicit 50% preterm fetal loss was 10-fold lower in IL-10(-/-) mice than in IL-10(+/+) mice. Surviving fetuses in IL-10(-/-) mice exhibited fetal growth restriction at lower doses of LPS than IL-10(+/+) mice. Marked elevation of LPS-induced immunoactive TNF-alpha and IL-6 was evident in the serum, uterus, and placenta of IL-10(-/-) mice, and TNF-alpha and IL-6 mRNA expression was elevated in the uterus and placenta, but not the fetus. Serum IL-1alpha, IFN-gamma, and IL-12p40 were increased and soluble TNFRII was diminished in the absence of IL-10, with these changes also reflected in the gestational tissues. Administration of rIL-10 to IL-10(-/-) mice attenuated proinflammatory cytokine synthesis and alleviated their increased susceptibility to preterm loss. Exogenous IL-10 also protected IL-10(+/+) mice from fetal loss. These data show that IL-10 modulates resistance to inflammatory stimuli by down-regulating proinflammatory cytokines in the uterus and placenta. Abundance of endogenous IL-10 in gestational tissues is therefore identified as a critical determinant of resistance to preterm labor, and IL-10 may provide a useful therapeutic agent in this common condition.

Uterine NK Cells Mediate Inflammation-Induced Fetal Demise in IL-10-Null Mice

Specialized NK cells are recruited in high numbers to the mammalian embryo implantation sites, yet remain pregnancy compatible. It is not well understood whether uterine NK (uNK) cells become adversely activated and mediate fetal demise, a common complication of early pregnancy. In this study we show that mating of IL-10(-/-) mice resulted in fetal resorption or intrauterine growth restriction in response to very low doses of LPS. Pregnancy in congenic wild-type mice was normal even at 10-fold higher LPS doses. Fetal resorption in IL-10(-/-) mice was associated with a significant increase in uNK cell cytotoxic activation and invasion into the placenta. Depletion of uNK cells, TNF-alpha neutralization, or IL-10 administration rescued pregnancy in LPS-treated IL-10(-/-) animals. Our results identify an immune mechanism of fetal demise involving IL-10 deficiency, NK cells, and inflammation. These results may provide insight into adverse pregnancy outcomes in humans.

Evidence for a role of phosphodiesterase 4 in lipopolysaccharide-stimulated prostaglandin E2 production and matrix metalloproteinase-9 activity in human amniochorionic membranes

Chorioamniotic infection is a leading cause of preterm premature rupture of fetal membranes (amnion and chorion). Bacterial infection induces an inflammatory response characterized by elevated production of proinflammatory cytokines; the latter activate the production of both PGs that stimulate uterine contractions, and matrix metalloproteinases (MMPs) that degrade the extracellular matrix of the chorioamniotic membranes. The inflammatory response is under the control of cAMP content, which is partly regulated by phosphodiesterases (PDE). In this study, we investigated the role of the PDE4 family in the inflammatory process triggered by LPS in a model of amniochorionic explants. We found that PDE4 family is the major cAMP-PDE expressed in human fetal membranes and that PDE4 activity is increased by LPS treatment. Selective inhibition of PDE4 activity affected LPS signaling, because PDE4 inhibitors (rolipram and/or cilomilast) reduced the release of the proinflammatory cytokine TNF-alpha and increased the release of the anti-inflammatory cytokine IL-10. PDE4 inhibition reduced cyclooxygenase-2 protein expression and PGE(2) production and also modulated MMP-9, a key mediator of the membrane rupture process, by inhibiting pro-MMP-9 mRNA expression and pro-MMP-9 activity. These results demonstrate that the PDE4 family participates in the regulation of the inflammatory response associated with fetal membrane rupture during infection. The PDE4 family may be an appropriate pharmacological target for the management of infection-induced preterm delivery.

Critical paracrine interactions between TNF-alpha and IL-10 regulate lipopolysaccharide-stimulated human choriodecidual cytokine and prostaglandin E2 production

Increased production of PGs by gestational membranes is believed to be a principal initiator of term and preterm labor. Intrauterine infection is associated with an inflammatory response in the choriodecidua characterized by elevated production of cytokines and PGs. The precise physiological significance of enhanced choriodecidual cytokine production in the mechanism of preterm labor remains uncertain. These studies were undertaken to dissect the roles and regulation of endogenous cytokines in regulating PG production by human choriodecidua. We used LPS treatment of human choriodecidual explants as our model system. In choriodecidual explant cultures, LPS (5 microg/ml) induced a rapid increase in TNF-alpha production, peaking at 4 h. In contrast, IL-10, IL-1beta, and PGE2 production rates peaked 8, 12, and 24 h, respectively, after LPS stimulation. Immunoneutralization studies indicated that TNF-alpha was a primary regulator of IL-1beta, IL-10, and PGE2 production, while IL-1beta stimulated only PGE2 production. Neutralization of endogenous IL-10 resulted in increased TNF-alpha and PGE2 production. IL-10 treatment markedly decreased TNF-alpha and IL-1beta production, but had no effect on PGE2 production. Taken together, these results demonstrate that the effects of LPS on choriodecidual cytokine and PG production are modulated by both positive and negative feedback loops. In the setting of an infection of the intrauterine, TNF-alpha may be a potential target for treatment intervention; IL-10 could be one such therapeutic.

Cytokines and other important inflammatory mediators in gestation and bacterial intraamniotic infections

Intraamniotic infections caused by viruses, bacteria or mycoplasmas are frequently followed by damage of fetus or increased perinatal morbidity and mortality. Cytokines are key substances regulating a number of biological processes including reproductive and inflammatory processes. An association between intraamniotic infections, rising concentrations of inflammatory cytokines in amniotic fluid and preterm labor is suggested. A great effort is made to find reliable markers typical for intraamniotic infections with high predictive value that make possible prompt identification of patients with intraamniotic infection. This review concerns inflammatory mediators, especially IL-1, IL-6, IL-8, TNF-alpha, and other important biologically active substances as prostaglandins and NO metabolites and their roles in intraamniotic infections. Finally, we discuss their relevance for diagnosis of intraamniotic infections.

Labor-associated changes in interleukin-10 production and its regulation by immunomodulators in human choriodecidua

Parturition is associated with increased production of proinflammatory mediators by gestational tissues. Interleukin-10 (IL-10) is an antiinflammatory cytokine produced by human chorion, decidual, and trophoblast tissues. To study the effects of immunomodulators on IL-10, IL-6, and PGE2 production by human choriodecidua before and after labor, an organ explant system was established. Tissue disks (6 mm) were excised from choriodecidual membranes obtained at term by cesarean section before labor (n=6-7) or after spontaneous vaginal delivery (n=7-8). After 24-h equilibration in medium, the tissues were treated with IL-1beta (10 ng/mL), tumor necrosis factor-alpha (100 ng/mL), lipopolysaccharide (5 microg/mL), dexamethasone (1 micromol/ L), or an appropriate vehicle control (n=3 wells/treatment) for 24 h. Media were harvested, and IL-10, IL-6, and PGE2 concentrations were determined by immunoassay. Basal choriodecidual production rates of IL-10 were significantly decreased with labor (P < 0.001), whereas PGE2 and IL-6 production rates increased. The production of all three substances was increased by IL-1beta, tumor necrosis factor-alpha, and lipopolysaccharide, but inhibited by dexamethasone. In contrast to PGE2 and IL-6, there was significantly increased responsiveness of IL-10 production to inflammatory stimuli after labor, but decreased responsiveness to the inhibitory effects of dexamethasone. These data indicate that IL-10 could play a role in modulating or promoting resolution of the inflammatory processes associated with labor at term and with intrauterine infection-associated preterm labor.

Pre-term labor: an intra-uterine inflammatory response syndrome?

Emerging concepts of sepsis suggest that the host response to an infectious stimulus results in some cases of uncontrolled release of inflammatory cytokines leading to signs of sepsis. Systemic inflammatory response syndrome (SIRS) has been suggested as a diagnosis when no etiologic organism can be found. Infection may account for up to 30% of cases of pre-term labor, and may either be clinically-evident or sub-clinical. Inflammatory cytokines can be detected in elevated concentrations in the amniotic fluid and plasma of women with pre-term labor, and human gestational tissues are potentially rich sources of inflammatory cytokines, as found in in vivo and in vitro studies. Also, maternal decidua and fetal membranes produce mRNA for inflammatory cytokines in the setting of infection-associated pre-term labor and normal term labor. Notably, anti-inflammatory cytokines, such as interleukin-10 (IL-10) do not appear to be present in substantial quantities in these pathophysiologic and physiologic conditions. Animal models indicate that pre-term labor can be stimulated by bacteria, bacterial cell wall products, and inflammatory cytokines such as IL-1 and tumor necrosis factor. These findings suggest that: (1) infectious stimuli may result in the liberation of inflammatory cytokines from gestational tissues leading inevitably to pre-term labor and delivery; (2) inhibition of this process may either be overcome or abrogated, and (3) the mechanisms regulating cytokine production in maternal and fetal tissues are disturbed. Thus, pre-term labor associated with sub-clinical infection may result in a dysregulated local inflammatory response, in which the maternal host response causes an 'intra-uterine inflammatory response syndrome' leading to pre-term labor and delivery.