Toll-like receptor-2 and toll-like receptor-4 expression on maternal neutrophils during pregnancy

Maternal Immunological Adaptation During Normal Pregnancy

The risk and severity of specific infections are increased during pregnancy due to a combination of physiological and immunological changes. Characterizing the maternal immune system during pregnancy is important to understand how the maternal immune system maintains tolerance towards the allogeneic fetus. This may also inform strategies to prevent maternal fatalities due to infections and optimize maternal vaccination to best protect the mother-fetus dyad and the infant after birth. In this review, we describe what is known about the immunological changes that occur during a normal pregnancy.

Early pregnancy-related changes in toll-like receptors expression in ovine trophoblasts and peripheral blood leukocytes

In the present study, we aimed to 1) demonstrate the presence of all 10 toll-like receptors (TLRs) in ovine trophoblasts, and 2) investigate the expression profiles of TLR1-10 mRNAs in peripheral blood leukocytes (PBLs) in ewes during early pregnancy. For those purposes, ovine trophoblasts (n = 6) were collected from pregnant ewes on day 13. PBLs were collected from non-pregnant (n = 6) and pregnant ewes (n = 17) on days of mating (d) 0 and 18. TLR mRNAs in ovine trophoblasts were visualized by free-floating in situ hybridization (ISH). To assess the expression profiles of TLR1-10 in PBLs, total RNA was isolated and transcribed to cDNA. TLR1-10 mRNA levels were determined by real-time PCR in triplicate. The Relative Expression Software Tool (REST 2009) was used for statistical analysis. We detected mRNAs for TLR2, TLR4, TLR5, TLR6, TLR7, TLR8, and TLR10 but not for TLR1, TLR3, and TLR9 in trophoblasts. TLR2, TLR5, TLR6, TLR7, TLR8, and TLR10 mRNAs were expressed by all trophoblasts, whereas TLR4 mRNA and protein in trophoblasts were more limited. In PBLs, TLR expression did not differ between day 0 and day 18 in non-pregnant ewes; however, ewes in early pregnancy exhibited significantly upregulated expression of TLR2 (2.3-fold), TLR4 (3.1-fold), TLR6 (1.7-fold), and TLR8 (2.2-fold) on day 18 compared with day 0. In contrast, TLR10 was downregulated (2-fold) on day 18 by pregnancy. Similar results were also obtained for TLR2, TLR4, TLR6, TLR8 and TLR10 from the comparison between day 18 non -pregnant and day 18 pregnant groups. According to these results, the presence of TLRs in early ovine trophoblasts suggests that these cells play an immunological role at the maternal-fetal interface. The results also suggest that tight regulation of some components of TLRs in PBLs due to embryo- and/or pregnancy-related factors is necessary for successful establishment of early pregnancy in ewes.

Novel Noncompetitive IL-1 Receptor-Biased Ligand Prevents Infection- and Inflammation-Induced Preterm Birth

Preterm birth (PTB) is firmly linked to inflammation regardless of the presence of infection. Proinflammatory cytokines, including IL-1β, are produced in gestational tissues and can locally upregulate uterine activation proteins. Premature activation of the uterus by inflammation may lead to PTB, and IL-1 has been identified as a key inducer of this condition. However, all currently available IL-1 inhibitors are large molecules that exhibit competitive antagonism properties by inhibiting all IL-1R signaling, including transcription factor NF-κB, which conveys important physiological roles. We hereby demonstrate the efficacy of a small noncompetitive (all-d peptide) IL-1R-biased ligand, termed rytvela (labeled 101.10) in delaying IL-1β-, TLR2-, and TLR4-induced PTB in mice. The 101.10 acts without significant inhibition of NF-κB, and instead selectively inhibits IL-1R downstream stress-associated protein kinases/transcription factor c-jun and Rho GTPase/Rho-associated coiled-coil-containing protein kinase signaling pathways. The 101.10 is effective at decreasing proinflammatory and/or prolabor genes in myometrium tissue and circulating leukocytes in all PTB models independently of NF-κB, undermining NF-κB role in preterm labor. In this work, biased signaling modulation of IL-1R by 101.10 uncovers a novel strategy to prevent PTB without inhibiting NF-κB.

Influenza, immune system, and pregnancy

Influenza is a major health problem worldwide. Both seasonal influenza and pandemics take a major toll on the health and economy of our country. The present review focuses on the virology and complex immunology of this RNA virus in general and in relation to pregnancy. The goal is to attempt to explain the increased morbidity and mortality seen in infection during pregnancy. We discuss elements of innate and adaptive immunity as well as placental cellular responses to infection. In addition, we delineate findings in animal models as well as human disease. Increased knowledge of maternal and fetal immunologic responses to influenza is needed. However, enhanced understanding of nonimmune, pregnancy-specific factors influencing direct interaction of the virus with host cells is also important for the development of more effective prevention and treatment options in the future.

Longitudinal expression of Toll-like receptors on dendritic cells in uncomplicated pregnancy and postpartum

OBJECTIVE

Toll-like receptors (TLRs) are integral parts of the innate immune system and have been implicated in complications of pregnancy. The longitudinal expression of TLRs on dendritic cells in the maternal circulation during uncomplicated pregnancies is unknown. The objective of this study was to prospectively evaluate TLRs 1-9 as expressed on dendritic cells in the maternal circulation at defined intervals throughout pregnancy and postpartum.

STUDY DESIGN

This was a prospective cohort of 30 pregnant women with uncomplicated pregnancies and 30 nonpregnant controls. TLRs and cytokine expression was measured in unstimulated dendritic cells at 4 defined intervals during pregnancy and postpartum. Basal expression of TLRs and cytokines was measured by multicolor flow cytometry. The percent-positive dendritic cells for each TLRs were compared with both nonpregnant and postpartum levels with multivariate linear regression.

RESULTS

TLRs 1, 7, and 9 were elevated compared with nonpregnant controls with persistent elevation of TLR 1 and interleukin-12 (IL-12) into the postpartum period. Concordantly, levels of IL-6, IL-12, interferon alpha, and tumor necrosis factor alpha increased during pregnancy and returned to levels similar to nonpregnant controls during the postpartum period. The elevated levels of TLR 1 and IL-12 were persistent postpartum, challenging notions that immunologic changes during pregnancy resolve after the prototypical postpartum period.

CONCLUSION

Normal pregnancy is associated with time-dependent changes in TLR expression compared with nonpregnant controls; these findings may help elucidate immunologic dysfunction in complicated pregnancies.

Do the placental barrier, parasite genotype and Toll-like receptor polymorphisms contribute to the course of primary infection with various Toxoplasma gondii genotypes in pregnant women?

Toxoplasma gondii has a highly clonal genetic structure classified into three major genetic types, I, II, and III, plus additional recombinant and atypical strains. In humans, type I and atypical strains usually associate with severe toxoplasmosis. Type II strains, predominantly identified in European countries and the United States, correlate with a differential course of toxoplasmosis. During pregnancy, the important protective role of the placenta against maternal–fetal T. gondii transmission has been reported. T. gondii preferentially colonizes extravillous trophoblasts as compared to syncytiotrophoblasts. The latter compartment was suggested to act as the real barrier to the fetal dissemination of T. gondii. Alterations in immune response to particular T. gondii strains were observed. Higher transcription levels of IP-10, IL-1β, IL-6, IL-10, IL-12 cytokines, and NF-κB translocation to the nucleus were more often documented for type II strains than type I strains. Since the induction of IL-12 during type II infection was Myd88-dependent, the involvement of Toll-like receptors (TLRs) in the immunity against these strains was suggested. Differential expression of TLRs depends on placental cell types and gestational age. The expression of TLR2 and TLR4 in the first trimester of pregnancy was reported only for villous cytotrophoblasts and extravillous trophoblasts, but not for syncytiotrophoblasts. The involvement of single-nucleotide polymorphisms (SNPs) in the TLR genes in infectious pathogenicity, including toxoplasmic retinochoroiditis, points at a possible involvement of TLR alterations in immunity against T. gondii. We conclude that studies on TLR contributions in the maternal–fetal transmission of particular parasite strains and congenital toxoplasmosis are warranted.

Expression of toll-like receptor 4 in maternal monocytes of patients with gestational diabetes mellitus

Toll-like receptors (TLRs) are pattern recognition receptors and play an important role in innate immune responses and the occurrence of inflammatory disease. TLR4 is a member of the TLR family and its activation is capable of inducing inflammatory responses, reflecting a relationship between the innate and adaptive immune systems. However, whether TLR4 is expressed in patients with gestational diabetes mellitus (GDM) has not been elucidated. The aim of the present study was to investigate whether TLR4 is expressed in maternal peripheral blood monocytes of patients with GDM. A case-control study, using standard quantitative polymerase chain reaction and western blotting, was performed to assess the TLR4 expression in 30 females with GDM and 32 healthy pregnant females at similar gestational ages. Serum tumor necrosis factor (TNF)-α levels were assessed using ELISA in all the females. The TLR4 expression levels in the maternal peripheral blood monocytes and the serum TNF-α levels were increased in females with GDM compared with healthy pregnant females (P<0.05). Additionally, there was a positive correlation between the TLR4 expression level in peripheral blood monocytes and serum TNF-α levels in all the females. These results indicate that TLR4-mediated release of inflammatory cytokines may represent one factor leading to increased glucose levels in patients with GDM. In addition, TLR4 may be involved in the pathogenesis of GDM.

Alterations in TLRs as new molecular markers of congenital infections with Human cytomegalovirus?

Toll-like receptors (TLRs) play a crucial role in non-specific immunity against various infections. The most common intrauterine infection, caused by Human cytomegalovirus (HCMV), results in perinatal morbidity and mortality of primary infected fetuses. The induction of immune response by TLRs was observed in HCMV infections in murine models and cell lines cultured in vitro. Studies reported an immunological response in pregnant women with primary HCMV infection and TLR2 activity in collecting of HCMV particles in placental syncytiotrophoblasts (STs) in vivo and cultured ST, and in stimulation of tumor necrosis factor (TNF)-α expression and damage of villous trophoblast. Expression levels of TLRs are associated with cell type, stage of pregnancy and response to microorganisms. We show the effect of HCMV infection on the development of pregnancy as well as the effect of TLR single-nucleotide polymorphisms on the occurrence and course of infectious diseases, immune response and diseases of pregnancy. We report the impact of TLRs on the function of miRNAs and the altered expression levels of these molecules, as observed in HCMV infections. We suggest that the methylation status of TLR gene promoter regions as epigenetic modifications may be significant in the immune response to HCMV infections. We conclude that it is important to study in detail the molecular mechanisms of TLR function in the immune response to HCMV infections in pregnancy.

Invariant NKT cells increase lipopolysacchride-induced pregnancy loss by a mechanism involving Th1 and Th17 responses

OBJECTIVE

To determine the role of invariant natural killer T (iNKT) cells in infection-associated pregnancy loss.

METHODS

B6 and iNKT cell-deficient Jα18(-/-) mice were injected i.p. with lipopolysaccharide (LPS) or vehicle, and pregnancy outcomes were examined. Decidual iNKT cell expression of CD69 and intracellular cytokine production were analyzed. Mouse decidual iNKT cells were co-cultured with LPS or PBS-treated dendritic cells (DCs), and iNKT cell CD69 expression and intracellular and extracellular cytokine production were assessed.

RESULTS

The embryo resorption rate was notably lessened for Jα18(-/-) mice treated with LPS on day 6 or day 9 gestation in comparison with B6 mice treated with LPS. Decidual iNKT cell CD69 expression and intracellular IFN-γ and IL-17 production for B6 mice injected with LPS on day 6 or day 9 gestation were significantly up-regulated compared with PBS-treated mice. Levels of IFN-γ and IL-17 in the supernatants of the co-culture of decidual iNKT cells and LPS-sensitized DCs were strikingly increased in comparison with the co-culture of iNKT cells and PBS-treated DCs. CD69 expression and intracellular IFN-γ and IL-17 production of iNKT cells co-cultured with LPS-sensitized DCs were remarkably up-regulated compared with iNKT cells co-cultured with PBS-treated DCs.

CONCLUSIONS

Our results suggest that iNKT cells may play a role in LPS-induced pregnancy loss by Th1 and Th17 cytokine-dependent manner.