Innate immune responses to malaria-infected erythrocytes in pregnant women: Effects of gravidity, malaria infection, and geographic location.

BACKGROUND: Malaria in pregnancy causes maternal, fetal and neonatal morbidity and mortality, and maternal innate immune responses are implicated in pathogenesis of these complications. The effects of malaria exposure and obstetric and demographic factors on the early maternal immune response are poorly understood. METHODS: Peripheral blood mononuclear cell responses to Plasmodium falciparum-infected erythrocytes and phytohemagglutinin were compared between pregnant women from Papua New Guinea (malaria-exposed) with and without current malaria infection and from Australia (unexposed). Elicited levels of inflammatory cytokines at 48 h and 24 h (interferon γ, IFN-γ only) and the cellular sources of IFN-γ were analysed. RESULTS: Among Papua New Guinean women, microscopic malaria at enrolment did not alter peripheral blood mononuclear cell responses. Compared to samples from Australia, cells from Papua New Guinean women secreted more inflammatory cytokines tumor necrosis factor-α, interleukin 1ß, interleukin 6 and IFN-γ; p<0.001 for all assays, and more natural killer cells produced IFN-γ in response to infected erythrocytes and phytohemagglutinin. In both populations, cytokine responses were not affected by gravidity, except that in the Papua New Guinean cohort multigravid women had higher IFN-γ secretion at 24 h (p = 0.029) and an increased proportion of IFN-γ+ Vδ2 γδ T cells (p = 0.003). Cytokine levels elicited by a pregnancy malaria-specific CSA binding parasite line, CS2, were broadly similar to those elicited by CD36-binding line P6A1. CONCLUSIONS: Geographic location and, to some extent, gravidity influence maternal innate immunity to malaria.

Increased HLA-G Expression in Term Placenta of Women with a History of Recurrent Miscarriage Despite Their Genetic Predisposition to Decreased HLA-G Levels.

Human leukocyte antigen (HLA)-G is an immune modulating molecule that is present on fetal extravillous trophoblasts at the fetal-maternal interface. Single nucleotide polymorphisms (SNPs) in the 3 prime untranslated region (3'UTR) of the HLA-G gene can affect the level of HLA-G expression, which may be altered in women with recurrent miscarriages (RM). This case-control study included 23 women with a medical history of three or more consecutive miscarriages who delivered a child after uncomplicated pregnancy, and 46 controls with uncomplicated pregnancy. Genomic DNA was isolated to sequence the 3'UTR of HLA-G. Tissue from term placentas was processed to quantify the HLA-G protein and mRNA levels. The women with a history of RM had a lower frequency of the HLA-G 3'UTR 14-bp del/del genotype as compared to controls (Odds ratio (OR) 0.28; p = 0.039), which has previously been related to higher soluble HLA-G levels. Yet, HLA-G protein (OR 6.67; p = 0.006) and mRNA (OR 6.33; p = 0.010) expression was increased in term placentas of women with a history of RM as compared to controls. In conclusion, during a successful pregnancy, HLA-G expression is elevated in term placentas from women with a history of RM as compared to controls, despite a genetic predisposition that is associated with decreased HLA-G levels. These findings suggest that HLA-G upregulation could be a compensatory mechanism in the occurrence of RM to achieve an ongoing pregnancy.

P. falciparum infection and maternofetal antibody transfer in malaria-endemic settings of varying transmission.

INTRODUCTION: During pregnancy, immunoglobulin G (IgG) is transferred from the mother to the fetus, providing protection from disease in early infancy. Plasmodium falciparum infections may reduce maternofetal antibody transfer efficiency, but mechanisms remain unclear. METHODS: Mother-cord paired serum samples collected at delivery from Papua New Guinea (PNG) and the Thailand-Myanmar Border Area (TMBA) were tested for IgG1 and IgG3 to four P. falciparum antigens and measles antigen, as well as total serum IgG. Multivariable linear regression was conducted to assess the association of peripheral P. falciparum infection during pregnancy or placental P. falciparum infection assessed at delivery with maternofetal antibody transfer efficiency. Path analysis assessed the extent to which associations between P. falciparum infection and antibody transfer were mediated by gestational age at delivery or levels of maternal total serum IgG. RESULTS: Maternofetal antibody transfer efficiency of IgG1 and IgG3 was lower in PNG compared to TMBA (mean difference in cord antibody levels (controlling for maternal antibody levels) ranged from -0.88 to 0.09, median of -0.20 log2 units). Placental P. falciparum infections were associated with substantially lower maternofetal antibody transfer efficiency in PNG primigravid women (mean difference in cord antibody levels (controlling for maternal antibody levels) ranged from -0.62 to -0.10, median of -0.36 log2 units), but not multigravid women. The lower antibody transfer efficiency amongst primigravid women with placental infection was only partially mediated by gestational age at delivery (proportion indirect effect ranged from 0% to 18%), whereas no mediation effects of maternal total serum IgG were observed. DISCUSSION: Primigravid women may be at risk of impaired maternofetal antibody transport with placental P. falciparum infection. Direct effects of P. falciparum on the placenta, rather than earlier gestational age and elevated serum IgG, are likely responsible for the majority of the reduction in maternofetal antibody transfer efficiency with placental infection.

Rapid and strong de novo donor-specific antibody development in a lung transplant recipient: Short communication/case report.

A 66-yo female patient (typed B*39:01, 44:02) underwent first left single lung transplant (typed B*81:01, 15:17) on 02/07/2016 with negative for DSA in current and historical samples. On 02/17/2016 strong de novo DSA (MFI=15,200, C1q+) to B81 were detected. The recipient has two children typed B*07:02, 44:02 B*27:03, 39:01, and had received multiple vaccinations. Twinrix, Zostavax and MMR vaccines contain viruses grown on live human lung fibroblasts (MRC-5, typed B*07:02, 44:02, and WI-38, typed B*08:01, 58:01). Each dose of vaccine used for injection is known to contain protein components of fibroblasts including HLA. Most likely rapid de novo DSA development is due to booster effect produced by five exposures to mismatched B locus alleles which share the following epitopes: 70IAQ, 65QIA, 65QIA+76esn, 69aa+80n, and 163ew+73te. The later three consist of paired non-self and self eplets. Although likelihood of bystander effect produced by multiple vaccinations is low its impact cannot be ruled out.

Helminth infection, fecundity, and age of first pregnancy in women.

Infection with intestinal helminths results in immunological changes that influence co-infections, and might influence fecundity by inducing immunological states affecting conception and pregnancy. We investigated associations between intestinal helminths and fertility in women, using 9 years of longitudinal data from 986 Bolivian forager-horticulturalists, experiencing natural fertility and 70% helminth prevalence. We found that different species of helminth are associated with contrasting effects on fecundity. Infection with roundworm (Ascaris lumbricoides) is associated with earlier first births and shortened interbirth intervals, whereas infection with hookworm is associated with delayed first pregnancy and extended interbirth intervals. Thus, helminths may have important effects on human fertility that reflect physiological and immunological consequences of infection.

Differential recognition of terminal extracellular Plasmodium falciparum VAR2CSA domains by sera from multigravid, malaria-exposed Malian women.

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediates parasite sequestration in small capillaries through tissue-specific cytoadherence. The best characterized of these proteins is VAR2CSA, which is expressed on the surface of infected erythrocytes that bind to chondroitin sulfate in the placental matrix. Antibodies to VAR2CSA prevent placental cytoadherence and protect against placental malaria. The size and complexity of the VAR2CSA protein pose challenges for vaccine development, but smaller constitutive domains may be suitable for subunit vaccine development. A protein microarray was printed to include five overlapping fragments of the 3D7 VAR2CSA extracellular region. Malian women with a history of at least one pregnancy had antibody recognition of four of these fragments and had stronger reactivity against the two distal fragments than did nulliparous women, children, and men from Mali, suggesting that the C-terminal extracellular VAR2CSA domains are a potential focus of protective immunity. With carefully chosen sera from longitudinal studies of pregnant women, this approach has the potential to identify seroreactive VAR2CSA domains associated with protective immunity against pregnancy-associated malaria.

Prior reproductive experience alters prolactin-induced macrophage responses in pregnant rats.

Reproductive experience (i.e., pregnancy and lactation) induces physiological changes in mammals. A previous reproductive experience was recently shown to modulate the activity of dopaminergic hypothalamic systems while decreasing serum prolactin levels and oxidative burst activity in peritoneal macrophages. Dopamine receptor antagonists increase serum prolactin levels, and both prolactin and dopamine receptors may be involved in the modulation of macrophage activity, providing a means of communication between the nervous and immune systems. The present study evaluated the in vitro effects of prolactin and a dopamine D2 receptor antagonist on the peritoneal activity of macrophages from primigravid and multigravid female rats during the third trimester of pregnancy. Oxidative bursts and phagocytosis in peritoneal macrophages were evaluated by flow cytometry. Primigravid and multigravid Wistar rats, during the third trimester of pregnancy (i.e., days 17-21), were used. Peritoneal fluid samples from these rats were first incubated with prolactin (10 and 100 nM) for different periods of time. The same procedure was repeated to evaluate the effects of domperidone (10 and 100 nM) on macrophage activity. Our results showed that macrophages from multigravid rats responded more effectively to in vitro incubation with prolactin, especially with regard to the intensity and percentage of phagocytosis. Additionally, these effects were more pronounced after incubation periods of 30 min or 4 h. These data suggest that macrophages during a second pregnancy become more sensitive to the phagocytotic effects of prolactin.

Plasma TNF-α levels are higher in early pregnancy in patients with secondary compared with primary recurrent miscarriage.

PROBLEM: Specific pro-inflammatory cytokine profiles in plasma may characterize women with recurrent miscarriage (RM) but the dynamics of the cytokine profiles with progressing pregnancy is largely unknown. METHOD OF STUDY: Plasma was repeatedly sampled in the first trimester from 47 RM patients. The concentrations of five cytokines including tumour necrosis factor alpha (TNF-α) were measured. TNF-α levels were correlated to carriage of five TNFA promoter polymorphisms. RESULTS: TNF-α levels increased (P = 0.014) with progressing pregnancy, with higher levels in secondary than primary RM (P = 0.042) but with no significant impact on outcome. Carriage of TNFA -863C and TNFA -1031T was associated with higher TNF-α levels, and the former was found more often in secondary than primary RM (P < 0.02). CONCLUSION: Plasma TNF-α levels increase during early pregnancy in RM women regardless of outcome, but are higher in secondary than primary RM, which may be partly genetically determined.

Within-woman change in regulatory T cells from pregnancy to the postpartum period.

Regulatory T cells (Treg cells) are an important area of investigation in human health and disease. In this study, the trajectory of percentage of Treg cells (defined as CD4+CD25+Foxp3+CD127--lymphocytes) was measured in the blood of 208 women during pregnancy and up to three additional times in the postpartum period (1, 6 and 12 months postpartum). Whether the trajectory was affected by gravidity, parity, neonatal sex, pet exposure, maternal atopic and asthma status, smoking, maternal race or other pregnancy factors was examined. Multilevel models were fit using full maximum likelihood methods and included both random and fixed effects. Overall, percentages of Treg cells increased from the prenatal to the postpartum period. Among women who were not atopic, nulliparous women had lower percentages of Treg cells over time compared with parous women. Atopic women with pets in the home during pregnancy had lower percentages of Treg cells than atopic women who did not have pets. The trajectory was not affected by the other factors investigated. We conclude that within-woman change in percentages of Treg cells may vary by time in relation to delivery, as well as by maternal atopic status and exposure to pets and number of prior births. The data did not indicate an overall decline in Treg cells in the postpartum period. Future work to better identify the role of Treg cells in successful pregnancy would ideally include a set of well characterized women sampled serially starting prior to pregnancy and throughout the postpartum period.

Influence of the mother's preceding pregnancies on fetal development and postnatal survival of the neonate, in normal pregnancy. An immunological phenomenon?

OBJECTIVES: The objective of this study is to test for an association between the sex of conceptuses of the mother's preceding pregnancies and fetal development and early neonatal survival in normal pregnancy. METHODS: A population of 27,243 neonates, including a subsample of 7,773 "newborn/mother/placenta units" were divided into cohorts according to the sex of the neonate and the sex and number of conceptuses of the mother's preceding pregnancies. The average birth weight, placenta weight and early neonatal mortality rate were measured for each cohort and compared. The "dose effect" of preceding pregnancy was tested by linear and quadratic regression analysis, and by chi-square trend test for linearity of proportions. RESULTS: The results have shown an association between these three variables and the preceding pregnancies of the mother. Fetal development and early survival of the neonate are positively associated with the mother's preceding pregnancies of same sex as the neonate, and negatively associated with the preceding pregnancies of opposite sex to the neonate. The strength of the phenomenon increases with parity, at least for the first three parities. The association is statistically significant. CONCLUSIONS: The association between fetal development and neonatal survival and preceding pregnancies of the mother would be compatible with the action of male and female specific antigens capable of affecting selective implantation of blastocysts, which commands subsequent fetal development as well as early neonatal survival.

Allergic women show reduced T helper type 1 alloresponses to fetal human leucocyte antigen mismatch during pregnancy.

Low-level alloreactivity between mother and fetus may provide stimulation for fetal T helper type 1 (Th1) cell immune maturation. This study explored the effects of human leucocyte antigen (HLA) mismatch on materno-fetal interactions detected as cytokine responses and lymphoproliferation in mixed lymphocyte reactions, and whether this was altered in allergic women (n = 62) who have a Th2 propensity compared with non-allergic women (n = 65). HLA-DRbeta1 mismatch was associated with significantly increased Th1 interferon (IFN)-gamma, Th2 interleukin (IL)-13 and lymphoproliferative responses by both mothers and fetuses. Allergic women showed significantly lower IFN-gamma Th1 production in response to HLA-DRbeta1 mismatch. The infants of these women also showed significantly lower IL-10 and lower IFN-gamma production relative to IL-13. Both HLA-DRbeta1 mismatch and maternal allergy had significant independent effects on maternal IFN-gamma Th1 responses. Maternal allergy modifies HLA-mediated alloreactivity between the mother and the fetus, reducing Th1 activation. This may affect the cytokine milieu at the materno-fetal interface and could be implicated in the attenuated Th1 responses observed commonly in infants of atopic mothers.

Platelet-specific alloantigens and antibodies in Tunisian women after three or more pregnancies.

Pregnancy may allow alloimmunization against human platelet antigens (HPA), which can lead to neonatal alloimmune thrombocytopenia (NAIT). The specificities of alloantibodies are closely related to the distribution of the HPA systems. A total of 281 Tunisian multiparous women (mean number of pregnancies: 4.5) were phenotyped for the HPA-1, -3 and -5 systems, by monoclonal antibody immobilization of platelet antigens (MAIPA). We searched for antibodies against HPA-1a, HPA-3a, HPA-5b and HPA-5a in HPA-1b1b, HPA-3b3b, HPA-5a5a and HPA-5b5b individuals, respectively. The gene frequencies were: 0.83 for HPA-1a, 0.17 for HPA-1b, 0.78 for HPA-3a, 0.22 for HPA-3b, 0.82 for HPA-5a and 0.18 for HPA-5b. Anti-HPA-5b antibodies were present in eight sera and anti-HPA-3a antibodies were present in one serum. The anti-HPA-5b system is the most frequently involved in platelet alloimmunization in Tunisian multiparous women. However, prospective trials are required to confirm this result and to determine the exact frequencies and clinical relevance of platelet alloantibodies in pregnant Tunisian women.

Recrudescent Plasmodium berghei from pregnant mice displays enhanced binding to the placenta and induces protection in multigravida.

Pregnancy-associated malaria (PAM) is associated with placenta pathology and poor pregnancy outcome but the mechanisms that control the malaria parasite expansion in pregnancy are still poorly understood and not amenable for study in human subjects. Here, we used a set of new tools to re-visit an experimental mouse model of pregnancy-induced malaria recrudescence, BALB/c with chronic Plasmodium berghei infection. During pregnancy 60% of the pre-exposed primiparous females showed pregnancy-induced malaria recrudescence and we demonstrated that the recrudescent P. berghei show an unexpected enhancement of the adherence to placenta tissue sections with a marked specificity for CSA. Furthermore, we showed that the intensity of parasitemia in primigravida was quantitatively correlated with the degree of thickening of the placental tissue and up-regulation of inflammation-related genes such as IL10. We also confirmed that the incidence of pregnancy-induced recrudescence, the intensity of the parasitemia peak and the impact on the pregnancy outcome decreased gradually from the first to the third pregnancy. Interestingly, placenta pathology and fetal impairment were also observed at low frequency among non-recrudescent females. Together, the data raise the hypothesis that recrudescent P. berghei displays selected specificity for the placenta tissue enabling on one hand, the triggering of the pathological process underlying PAM and on the other hand, the induction of PAM protection mechanisms that are revealed in subsequent pregnancies. Thus, by exploiting P. berghei pregnancy-induced recrudescence, this experimental system offers a mouse model to study the susceptibility to PAM and the mechanisms of disease protection in multigravida.

Pregnancy IFN-gamma responses to foetal alloantigens are altered by maternal allergy and gravidity status.

BACKGROUND: During pregnancy, variations in maternal-foetal cellular interactions may influence immune programming. This study was carried out to determine if maternal responses to foetal alloantigens are altered by maternal allergic disease and/or previous pregnancies. METHODS: For this cohort study, peripheral blood was collected from allergic (n = 69) and nonallergic (n = 63) pregnant women at 20, 30, 36-week gestation and 6-week postpartum (pp). Cord blood was collected at delivery. Mixed lymphocyte reactions were used to measure maternal cytokine responses [interleukin-6 (IL-6), IL-10, IL-13 and (interferon-gamma) IFN-gamma] at each time point towards foetal mononuclear cells. RESULTS: Maternal cytokine responses during pregnancy (20, 30 and 36 weeks) were suppressed compared to the responses at 6-week pp. The ratio of maternal IFN-gamma/IL-13 and IFN-gamma/IL-10 responses were lower during pregnancy. Allergic mothers had lower IFN-gamma responses at each time-point during pregnancy with the greatest difference in responses observed at 36-week gestation. When allergic and nonallergic women were further stratified by gravidity group, IFN-gamma responses of allergic multigravid mothers were significantly lower than nonallergic multigravid mothers during pregnancy. CONCLUSIONS: During normal pregnancy, peripheral T-cell cytokine responses to foetal alloantigens may be altered by both allergic status of the mother and previous pregnancies. These factors could influence the cytokine milieu experienced by the foetus and will be further explored in the development of allergic disease during early life.

Monocyte chemoattractant protein-1 (CCL-2) integrates mechanical and endocrine signals that mediate term and preterm labor.

Recent evidence suggests that leukocytes infiltrate uterine tissues at or around the time of parturition, implicating inflammation as a key mechanism of human labor. MCP-1 (also known as C-C chemokine motif ligand 2, CCL-2) is a proinflammatory cytokine that is up-regulated in human myometrium during labor. Myometrium was collected from pregnant rats across gestation and at labor. Total RNA and proteins were subjected to real-time PCR and ELISA, respectively. Ccl-2 gene and protein expression was significantly up-regulated in the gravid rat myometrium before and during labor, which might suggest that it is regulated positively by mechanical stretch of the uterus imposed by the growing fetus and negatively by physiological withdrawal of progesterone (P4). We confirmed in vivo that: 1) administration of P4 receptor antagonist RU486 induced an increase in Ccl-2 mRNA and preterm labor, whereas 2) artificial maintenance of elevated P4 levels at late gestation caused a significant decrease in gene expression and blocked labor; 3) Ccl-2 was elevated specifically in the gravid horn of unilaterally pregnant rats suggesting that mechanical strain imposed by the growing fetus controls its expression in the myometrium; 4) in vitro static mechanical stretch of primary rat myometrial smooth muscle cells (25% elongation) induced a release of Ccl-2 protein, which was repressed by pretreatment with P4 (1 microM); and 5) stretch enhanced their monocyte chemoattractant activity. These data indicate that Ccl-2 protein serves to integrate mechanical and endocrine signals contributing to uterine inflammation and the induction of labor and thus may represent a novel target for therapeutic prevention of preterm labor in humans.

NK cells and pre-eclampsia.

Pre-eclampsia, a disease of pregnancy, is a cause of maternal and fetal mortality worldwide and a major factor in preterm birth. Up to 10% of primipara suffer from this disorder, characterized by pregnancy-induced hypertension and proteinuria, usually in the third trimester when fetal demands on the placenta are greatly increased. The disease is thought to stem from an insufficiency in utero-placental blood flow triggering a cascade of events leading to the maternal syndrome, which may have been initiated by defective placentation early in pregnancy. Theories abound as to the primary cause of the placental pathologies associated with the disease, including those based on maternal immunity and the unique immune environment of the placental bed. Accumulating evidence from animal models, genetic studies, and isolated decidual leukocytes suggests that decidual natural killer (NK) cells supply factors necessary for development and arterial modification of the maternal-fetal interface. This beneficial role of NK cells to normal placentation may shed light on the cause of the placental pathologies observed in pre-eclampsia.

Maternal reactivity to fetal alloantigens is related to newborn immune responses and subsequent allergic disease.

BACKGROUND: Maternal allergy confers stronger allergy risk (than paternal allergy) suggesting that maternal patterns of immune response can directly influence immune development in offspring. Women prone to allergic immune responses to allergens may also have altered immune responses to other antigens including fetal antigens. OBJECTIVE: This exploratory study examines relationships between maternal immune responses to fetal antigens and the subsequent risk of allergy. METHODS: Mononuclear cells (MNC) were collected from 36 mother-infant pairs to compare maternal (and fetal) cellular immune responses to alloantigens (fetal, maternal or unrelated donor [URD]), and allergens in allergic (18 pairs) and non-allergic (18 pairs) mothers. Thirty children had documented allergic outcomes at 6 years of age. RESULTS: In this population, allergic outcomes in the offspring were associated more strongly with materno-fetal immune interactions than with a maternal family history of allergy. Specifically, allergic disease at 6 years of age was associated with significantly higher maternal responses to fetal alloantigens (lymphoproliferation, P=0.008; IL-13, P=0.02 and IFN-gamma, P=0.015), whereas associations with maternal allergy did not reach significance (P=0.07). Fetal IFN-gamma alloantigen responses were significantly correlated with the degree of human lymphocyte antigen (HLA) mismatch (maternal HLA class II antibodies) (tau=0.3, P=0.03). The capacity of the fetus to produce IL-13 (tau=0.4, P=0.001) and IL-10 (tau=0.3, P=0.029) was directly related to the level of these cytokines produced by the mother in response to fetal antigens. Allergic mothers showed a non-significant trend for stronger lymphoproliferation to fetal alloantigens. The number of previous pregnancies (gravidity) was associated with stronger maternal responses to fetal alloantigens, as shown by lymphoproliferation (Kendall tau=0.3, P=0.04) and IFN-gamma (tau=0.3, P=0.04) synthesis, but did not affect fetal responses to the various stimuli. CONCLUSIONS: Maternal responses to fetal antigens were related to fetal immune responses and subsequent allergy. This novel observation suggests that events at the materno-fetal interface have an important influence on early immune development and should be investigated further.

Th2/Th3 cytokine genotypes are associated with pregnancy loss.

Cytokines are critical immunoregulatory molecules, responsible for determining the nature of an immune response. It has been proposed that Th2/Th3 immune reactions support normal pregnancy, while Th1 immunity is considered detrimental to the fetus. Since cytokine production is partly under genetic control, it is possible that women suffering from a high incidence of abortions are genetically predisposed to mount a type of immune response inappropriate for pregnancy maintenance. This study investigated the frequencies of cytokine gene polymorphisms in abortion-prone women and women with successful pregnancies. We investigated the role of Th1/Th2/Th3 cytokine gene polymorphisms, such as TGF-beta1 codon 10 (TGFbetac10; C to T), TGF-beta1 codon 25 (TGFbetac25; G to C), TNFalpha promoter-308 (G to A), IL-6 promoter-174 (G to C), IL-10 promoter-1082 (G to A), IL-10 promoter-819 (C to T), IL-10 promoter-592 (C to A), and IFNgamma intron 1 +874 (A to T) in abortion-prone female patients. Our results support the importance of Th2/Th3 immune responses in pregnancy loss, and suggest that an individual's immunogenetic profile indicative of imbalances in Th2/Th3 cytokines is associated with pregnancy loss. Our results suggest that abortive events are determined by genetic factors, reflected in the female patient's immunogenetic profile.