Activation Of Maternal Immune System Research Articles

Zika virus vertical transmission induces neuroinflammation and synapse impairment in brain cells derived from children born with Congenital Zika Syndrome

Zika virus (ZIKV) infection was first reported in 2015 in Brazil as causing microcephaly and other developmental abnormalities in newborns, leading to the identification of Congenital Zika Syndrome (CZS). Viral infections have been considered an environmental risk factor for neurodevelopmental disorders outcome, such as Autism Spectrum Disorder (ASD). Moreover, not only the infection per se, but maternal immune system activation during pregnancy, has been linked to fetal neurodevelopmental disorders. To understand the impact of ZIKV vertical infection on brain development, we derived induced pluripotent stem cells (iPSC) from Brazilian children born with CZS, some of the patients also being diagnosed with ASD. Comparing iPSC-derived neurons from CZS with a control group, we found lower levels of pre- and postsynaptic proteins and reduced functional synapses by puncta co-localization. Furthermore, neurons and astrocytes derived from the CZS group showed decreased glutamate levels. Additionally, the CZS group exhibited elevated levels of cytokine production, one of which being IL-6, already associated with the ASD phenotype. These preliminary findings suggest that ZIKV vertical infection may cause long-lasting disruptions in brain development during fetal stages, even in the absence of the virus after birth. These disruptions could contribute to neurodevelopmental disorders manifestations such as ASD. Our study contributes with novel knowledge of the CZS outcomes and paves the way for clinical validation and the development of potential interventions to mitigate the impact of ZIKV vertical infection on neurodevelopment.

Role of Maternal Immune Factors in Neuroimmunology of Brain Development.

Inflammation during pregnancy may occur due to various factors. This condition, in which maternal immune system activation occurs, can affect fetal brain development and be related to neurodevelopmental diseases. MIA interacts with the fetus's brain development through maternal antibodies, cytokines, chemokines, and microglial cells. Antibodies are associated with the development of the nervous system by two mechanisms: direct binding to brain inflammatory factors and binding to brain antigens. Cytokines and chemokines have an active presence in inflammatory processes. Additionally, glial cells, defenders of the nervous system, play an essential role in synaptic modulation and neurogenesis. Maternal infections during pregnancy are the most critical factors related to MIA; however, several studies show the relation between these infections and neurodevelopmental diseases. Infection with specific viruses, such as Zika, cytomegalovirus, influenza A, and SARS-CoV-2, has revealed effects on neurodevelopment and the onset of diseases such as schizophrenia and autism. We review the relationship between maternal infections during pregnancy and their impact on neurodevelopmental processes.

“Comparative evaluation of different chemical agents induced Autism Spectrum Disorder in experimental Wistar rats”

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition with uncertain etiology and pathophysiology. Several studies revealed that the commonly used animal models like Valproic Acid (VPA) and Propionic Acid (PPA) do not precisely represent the disease as the human patient does. The current study was conducted on different chemically (VPA, PPA, Poly I:C, Dioxin (2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)) & Chlorpyrifos (CPF)) induced ASD-like animal models and validated the best suitable experimental animal model, which would closely resemble with clinical features of the ASD. This validated model might help to explore the pathophysiology of ASD. This study included rat pups prenatally exposed to VPA, PPA, Poly I:C, Dioxin & CPF within GD9 to GD15 doses. The model groups were validated through developmental and behavioral parameters, Gene Expressions, Oxidative Stress, and Pro-inflammatory and Anti-inflammatory cytokines levels. Developmental and neurobehavioral parameters showed significant changes in model groups compared to the control. In oxidative stress parameters and neuro-inflammatory cytokines levels, model groups exhibited high oxidative stress and neuro-inflammation compared to control groups. Gene expression profile of ASD-related genes showed significant downregulation in model groups compared to the control group. Moreover, the Poly I:C group showed more significant results than other model groups. The comparison of available ASD-like experimental animal models showed that the Poly I:C induced model represented the exact pathophysiology of ASD as the human patient does. Poly I:C was reported in the maternal immune system activation via the inflammatory cytokines pathway, altering embryonic development and causing ASD in neonates.

Disruptions in Hypothalamic-Pituitary-Gonadal Axis Development and Their IgG Modulation after Prenatal Systemic Inflammation in Male Rats.

The development of the neuroendocrine system, including the hypothalamic-pituitary-gonadal (HPG) axis, is sensitive to environmental impacts during critical developmental periods. Maternal immune system activation by bacterial or viral infection may be one of the negative impacts. This study focused on the effect of systemic inflammation induced by lipopolysaccharides (LPS E. coli) on the HPG axis development in male rat offspring, corrected by the anti-inflammatory action of polyclonal IgG and monoclonal anti-interleukin (IL)-6 receptor antibodies (IL-6RmAbs). A single LPS exposure on the 12th embryonic day (ED) led to a decrease in the number of afferent synaptic inputs on gonadotropin-releasing, hormone-producing neurons in adult male offspring. LPS exposure on ED18 did not lead to such disruptions. Moreover, after the LPS injections on ED12, circulating follicle-stimulating hormone and sex steroid levels were reduced, and the gonadal structure was disrupted. A prenatal IL-6R blockade with IL-6RmAbs and polyclonal IgG reduced the negative effects of inflammation on fetal HPG axis development. Overall, the data obtained confirm the morphogenetic effect of inflammation on fetal HPG development and IL-6 involvement in these processes.

S100B dysregulation during brain development affects synaptic SHANK protein networks via alteration of zinc homeostasis

Autism Spectrum Disorders (ASD) are caused by a combination of genetic predisposition and nongenetic factors. Among the nongenetic factors, maternal immune system activation and zinc deficiency have been proposed. Intriguingly, as a genetic factor, copy-number variations in S100B, a pro-inflammatory damage-associated molecular pattern (DAMP), have been associated with ASD, and increased serum S100B has been found in ASD. Interestingly, it has been shown that increased S100B levels affect zinc homeostasis in vitro. Thus, here, we investigated the influence of increased S100B levels in vitro and in vivo during pregnancy in mice regarding zinc availability, the zinc-sensitive SHANK protein networks associated with ASD, and behavioral outcomes. We observed that S100B affects the synaptic SHANK2 and SHANK3 levels in a zinc-dependent manner, especially early in neuronal development. Animals exposed to high S100B levels in utero similarly show reduced levels of free zinc and SHANK2 in the brain. On the behavioral level, these mice display hyperactivity, increased stereotypic and abnormal social behaviors, and cognitive impairment. Pro-inflammatory factors and zinc-signaling alterations converge on the synaptic level revealing a common pathomechanism that may mechanistically explain a large share of ASD cases.

Brain Structural and Functional Alterations in Mice Prenatally Exposed to LPS Are Only Partially Rescued by Anti-Inflammatory Treatment.

Aberrant immune activity during neurodevelopment could participate in the generation of neurological dysfunctions characteristic of several neurodevelopmental disorders (NDDs). Numerous epidemiological studies have shown a link between maternal infections and NDDs risk; animal models of maternal immune activation (MIA) have confirmed this association. Activation of maternal immune system during pregnancy induces behavioral and functional alterations in offspring but the biological mechanisms at the basis of these effects are still poorly understood. In this study, we investigated the effects of prenatal lipopolysaccharide (LPS) exposure in peripheral and central inflammation, cortical cytoarchitecture and behavior of offspring (LPS-mice). LPS-mice reported a significant increase in interleukin-1β (IL-1β) serum level, glial fibrillary acidic protein (GFAP)- and ionized calcium-binding adapter molecule 1 (Iba1)-positive cells in the cortex. Furthermore, cytoarchitecture analysis in specific brain areas, showed aberrant alterations in minicolumns’ organization in LPS-mice adult brain. In addition, we demonstrated that LPS-mice presented behavioral alterations throughout life. In order to better understand biological mechanisms whereby LPS induced these alterations, dams were treated with meloxicam. We demonstrated for the first time that exposure to LPS throughout pregnancy induces structural permanent alterations in offspring brain. LPS-mice also present severe behavioral impairments. Preventive treatment with meloxicam reduced inflammation in offspring but did not rescue them from structural and behavioral alterations.

Developmental influences on schizophrenia-like cognitive and neurophysiological outcomes in a rat model of maternal immune challenge

The developing brain is sensitive to early-life insults, which can increase the risk of neuropsychiatric disorders such as schizophrenia. Maternal immune system activation during gestation via infection is a known risk factor for schizophrenia. Here we examine the role of early-life immune activation on schizophrenia-related behavioural and electrophysiological outcomes. Pregnant Wistar rats were injected with the viral mimic, Poly(I:C) or vehicle at either gestational day (GD) 10 or GD19. Adult offspring were examined for behaviour (prepulse inhibition (PPI) and working memory) and electrophysiology (generation 50Hz auditory steady-state responses (aSSRs)).Brain tissue was examined for NMDA receptor (NMDAR) binding. Rats exposed to Poly(I:C) at GD10 were found to exhibit reduced PPI, whereas those exposed to Poly(I:C) during late gestation exhibited working memory impairments. In addition, late gestation-exposed rats exhibited reduced power of 50Hz aSSRs, indicating an impaired ability to generate neural oscillations in the high-frequency (gamma) range. Adult offspring exposed to Poly(I:C) on GD19 had increased binding to the NMDAR2A subunit and the NMDAR channel in the hippocampus. Maternal immune activation via a viral mimic was sufficient to alter the trajectory of brain development such that there were long-term impacts of several behavioural and electrophysiological outcomes in adulthood. Several of the behavioural and electrophysiological changes identified here are also found in patients with schizophrenia, indicating that the Maternal Immune Activated rat may model aspects of the disorder.

Abstract P612: TLR3-Induced Placental miR-155 Contributes to Preeclampsia by Augmenting Inflammation

Hypertensive disorders of pregnancy including preeclampsia (PE) affect ~15% of all pregnancies. We have previously demonstrated that excessive maternal immune system activation via Toll-like receptor 3 (TLR3) contributes to the development of PE-like symptoms such as hypertension, endothelial dysfunction, and proteinuria in mice only when pregnant. Recently, increased miR-155 (an inflammation-related miRNA) expression was reported in placentas from women with PE compared to normotensive women suggesting a pathophysiological role of miR-155 in PE. Whether miRNAs play a role in the etiology of PE by augmenting inflammation is unknown. We confirmed miR-155 expression was up-regulated in placentas of poly I:C (a TLR3 agonist) treated wild type mice by microarray (P-PIC: 1.56 fold, p<0.5 vs controls) and qRT-PCR analyses (P-PIC: 3.15 fold, p<0.05 vs. controls). Based on our data we hypothesized that TLR3 activation induces placental miR-155 expression that augments maternal inflammation leading to PE. Transcription factors NF-κB and AP-1 which are known to bind to the promoter of miR-155 were increased in placentas of P-PIC mice. TargetScan, a target identification algorithm predicted suppressor of cytokine signaling 1 (SOCS1) as a putative target of miR-155. SOCS1 prevents overactivation of immune responses but failed to increase in P-PIC mice. ICAM, a marker of inflammation increased significantly in P-PIC mice. P-PIC TLR3 KO mice did not develop hypertension and proteinuria as well as did not exhibit increased placental levels of NF-κB, AP-1, miR-155 expression and ICAM or decreased levels of SOCS1. To determine the placental etiology, human cytotrphoblasts (CTBs) were treated with poly I:C and NF-κB, AP-1 transcription factor levels and miR-155 expression were increased significantly while SOCS1 levels decreased. Together, these data suggest that TLR3 activation increases placental miR-155 expression which downregulates SOCS1 levels and increases inflammation which may contribute to the development of PE.

Decreased alloreactivity toward non-inherited maternal antigen (NIMA) allows successful kidney transplantation in regraft patient: Case report

Background During pregnancy contact with paternal HLA-antigen can lead to activation of maternal immune system while exposure of the child to the non inherited (NIMA) antigens may lead to tolerance due to immaturity of the child immune system in utero. Multiple studies on hematopoietic stem cell transplantation demonstrate this beneficial effect but studies on NIMA-specific tolerance in renal transplant are generally few and demonstrated improved kidney graft from sibling who is mismatched at the NIMA haplotype. We report here a case of a successful kidney retansplant from a sibling who is mismatched at the NIMA after failed initial graft from the mother. 26-year-old female with ESRD was referred for second kidney transplantation. Her mother offered the first graft which shortly after the transplantation possibly due to chronic rejection. Investigation revealed weak DSA against DQ2. A haploidentical brother offered the second NIMA-mismatched graft. FXM results were negative for both T and B with second donor. She received Thymoglobulin induced second transplant from her brother. The first post transplant SAB results showed remarkable increase in DQ2, MFI of 11380. We alerted the clinician to this increment in DSA, so he put the patient under close observation despite normal creatinine level. A kidney biopsy was unremarkable. Because of persistence elevation of DSA in view of normal kidney function the treating team questioned our reports and a second biopsy was performed which showed the same findings, however C4d was focally positive in the second biopsy. Consequently the patient received full rejection therapy. The lack of expected response in DSA level guided us to reanalyze our data. HR typing confirmed HLA-DQB1∗02:02 associated with DQA1∗02:01 for both donors but careful analysis of DQ2 coated bead reaction showed that what we reported as DSA was actually non donor specific and directed against sub group of DQ2 indicating tolerance to mismatch NIMA despite repeated exposures. Our case is a further confirmation for the superior graft outcome from sibling expressing NIMA compared to maternal graft expressing the same NIMA.

Cotreatment with interleukin 4 and interleukin 10 modulates immune cells and prevents hypertension in pregnant mice.

Excessive maternal immune system activation plays a central role in the development of the hypertensive disorder of pregnancy preeclampsia (PE). The immunomodulatory cytokines interleukin 4 (IL-4) and interleukin 10 (IL-10) are dysregulated during PE; therefore we hypothesized that treatment with both recombinant IL-4 and IL-10 during pregnancy could prevent the development of PE in mice. Using our mouse model of PE in which immune system activation is induced by the double-stranded RNA receptor agonist poly I:C, we gave daily injections of IL-4, IL-10, or both on days 13-17 of pregnancy. Mice were then killed on day 18. Poly I:C caused a significant increase in systolic blood pressure in pregnant (P-PIC) mice compared with vehicle-treated pregnant (P) mice. All 3 treatments significantly decreased blood pressure in P-PIC mice to P levels, ameliorated the endothelial dysfunction, and decreased placental TLR3 levels in P-PIC mice. However, only IL-4/IL-10 cotreatment prevented the proteinuria and increased incidence of fetal demise in P-PIC mice; IL-4 or IL-10 alone had no effect. Additionally, only IL-4/IL-10 cotreatment prevented the significant increase in CD3(+)/γδ(+) T cells and CD11c(+) dendritic cells and significant decrease in CD11b(+)/CD14(-) suppressor monocytes, as well as completely prevented placental necrosis, in P-PIC mice. Importantly, IL-4/IL-10 cotreatment in P mice had no detrimental effects. Taken together, these data demonstrate that exogenous IL-4 and IL-10 administration concurrently during pregnancy can normalize immune cell subsets and prevent PE induced by maternal immune system activation.

Effects of Activation of Maternal Immune System at Early Stages of Pregnancy on Antitumor Immunity of the Progeny

The effects of maternal immune system on the formation and functioning of the fetus is an important problem. Single stimulation of immune system of female C57Bl/6 mice with concanavalin A at the early stages of pregnancy before the formation of fetal immune organs was followed by impairment of antitumor immunity in the progeny by the time of puberty. These changes manifested in the increased survival rate of B16 melanoma, high rate of death of tumor-bearing animals, and low cytotoxic activity of spleen cells on L-929 fibrosarcoma cells.

Abstract 7: Both Maternal Systemic and Paternal-Derived Placental Trophoblast TLR3 Activation Are Necessary for the Development of Preeclampsia in Mice

Preeclampsia (PE) is a pregnancy-specific hypertensive disorder which affects ~8% of all pregnancies worldwide. The placenta is considered to be the main culprit in the etiology of PE as the symptoms of PE typically abate following removal of the placenta. PE is also known to be mediated in part by excessive maternal immune system activation and inflammation. We developed a mouse model of PE by excessively activating TLR3, which recognizes dsRNA from necrotic tissue and viruses; however, it is unknown whether TLR3 activation in maternal systemic cells, in paternally-derived placental trophoblasts, or both play a role in the development of hypertension during pregnancy. We hypothesized that both contribute and to test this we used the following mating schemes: 1) female WT mice mated with male WT mice (control), 2) female TLR3 KO mated with WT male (Ma TLR3 KO, TLR3 deficiency in all maternal cells), 3) male TLR3 KO mated with female WT (Pa TLR3 KO, TLR3 deficiency in paternally-derived trophoblasts, the major cell type in the placenta), and 4) female TLR3 KO mated with male TLR3 KO (MaPa TLR3 KO, TLR3 deficiency in all maternal cells and trophoblasts). Pregnant WT and TLR3 KO (Ma, Pa, and MaPa) mice were subjected to poly I:C or saline treatment on gestational days 13, 15, and 17. Poly I:C treatment induced pregnancy-dependent hypertension in pregnant WT mice (PPIC WT) (day 17 SBP in mmHg: PPIC WT: 147±5 vs. P WT: 100±4; p<0.05), however this was attenuated in PPIC Ma TLR3 KO mice (109±2 mmHg; p<0.05 vs. P WT) and PPIC Pa TLR3 KO mice (109±1 mmHg; p<0.05 vs. P WT), and completely normalized in PPIC MaPa TLR3 KO mice (102±3 mmHg; P>0.05 vs. P WT). PPIC WT mice exhibited endothelial dysfunction, proteinuria, and increased fetal demise compared to P WT mice which were attenuated in PPIC Ma TLR3 KO and PPIC Pa TLR3 KO mice, but completely normalized in PPIC MaPa TLR3 KO mice. PPIC WT mice exhibited splenomegaly which was only completely reduced in PPIC MaPa TLR3 KO mice. In conclusion, our data suggest that both maternal systemic and paternal-derived placental trophoblast TLR3 activation contribute to the full development of PE-like symptoms in mice.

Is immune system activation/systemic inflammation a prerequesite for successful reproduction? association of immune system activation with embryo quality during in vitro fertilization (IVF)

Requiring implantation and tolerance of semi-allograft, pregnancy mandates complex immunological processes. Degree of immune system activation has been associated with pregnancy complications. Effects of immune system activation on embryo quality has, however, never been investigated. Cohort study. 125 infertile women underwent 169 IVF cycles. Embryo quality was defined as good (4-cell d-2; 8-cell d-3, Grade 4-5), poor (arrested or degenerated, Grade ≤ 2) or fair (all embryos in between). Immune system activation was tested utilizing immune parameters, demonstrated effective in prior studies in identifying immune system activation with good sensitivity: thyroid antibodies (peroxidase, thyroglobulin, thyroid receptor antibodies), total immunoglobulins (IgG, IgM, IgA, IgE), antiphospholipid antibodies (β2 glycoprotein, anticardiolipin, antiphosphatidylserine, lupus anticoagulant), antinuclear antibody, anti-adrenal antibody (21-hydroxylase) and anti-ovarian antibodies. Any positive finding was considered indicative of immune activation. Patient age was 38.9 ± 5.5 years. Immune system activation was associated with significantly better embryo quality (P=0.008). This association persisted after adjustment for age and repeat IVF cycles (P=0.006). Observed improvement in embryo quality derived mostly from better embryo grade (3.7 ± 0.05 vs. 3.4 ± 0.07, P=0.002). This is the first report associating improved embryo quality with maternal immune system activation. These data relate to recent report from our center that normal androgen levels appear associated with immune system activation, while low androgen levels fail to show such activation (Gleicher et al ESHRE 2013/Reprod Biol Encocrinol 2013; In press). Combined, these data suggest that immune system activation/systemic inflammation, possibly via androgen effects on follicle maturation, contributes to embryo quality and pregnancy success with IVF.

Abstract 208: TLR3-Induced Placental miR-210 Down-Regulates the STAT6/IL-4 Pathway

Several clinical studies have reported differential expression of microRNAs (miRs) in placentas from women with preeclampsia (PE) compared to normotensive women. Whether or not miRs play a role in the etiology of PE is unknown. Given the important role of maternal immune system activation and inflammation in PE, we developed a mouse model of PE via activation of Toll-like receptor 3 (TLR3) which exhibit hypertension, endothelial dysfunction, and proteinuria only when pregnant. miR-210 is increased in placentas of women with PE, but whether TLR3 activation in pregnant mice and human cytotrophoblasts (CTBs) increases miR-210 and the effects on miR-210 targets related to inflammation are unknown. miR-210 expression was up-regulated in placentas of poly I:C-treated control mice (P-PIC: 4.9 fold, p<0.05 vs. controls) similar to that in women with PE. Both HIF-1α and NF-κB p50 are known to bind to the promoter of miR-210 and induce its expression. HIF-1α (1.5 fold, p<0.05 vs. controls) and NF-κB p50 (2.7 fold, p<0.05 vs. controls) expression were increased significantly in placentas of P-PIC mice. Target identification algorithms and gene ontology predicted STAT6 as a target of miR-210 related to inflammation and STAT6 was decreased significantly in placentas of P-PIC mice. Increased production of the anti-inflammatory cytokine IL-4, which is regulated by STAT6, plays a critical role during normotensive pregnancy but failed to increase in P-PIC mice. Pregnant TLR3 KO mice treated with poly I:C, which did not develop hypertension, did not have increased placental expression of HIF-1α, NF-κB p50, and miR-210 or decreased expression of STAT6 and IL-4. To determine the placental etiology, human CTBs were treated with poly I:C and HIF-1α, NF-κB p50, and miR-210 expression were increased significantly while STAT6 and IL-4 expression decreased significantly. Inhibition of miR-210 in CTBs using anti-miR-210 significantly increased STAT6 and IL-4 expression and overexpression of miR-210 decreased STAT6 and IL-4 expression in CTBs. Taken together our data suggest that TLR3 activation induces placental miR-210 via HIF-1α and NF-κB p50 which in turn decreases STAT6 and IL-4 expression and may contribute to the development of PE.

Placental Toll-Like Receptor 3 and Toll-Like Receptor 7/8 Activation Contributes to Preeclampsia in Humans and Mice

Preeclampsia (PE) is a pregnancy-specific hypertensive syndrome characterized by excessive maternal immune system activation, inflammation, and endothelial dysfunction. Toll-like receptor (TLR) 3 activation by double-stranded RNA (dsRNA) and TLR7/8 activation by single-stranded RNA (ssRNA) expressed by viruses and/or released from necrotic cells initiates a pro-inflammatory immune response; however it is unknown whether viral/endogenous RNA is a key initiating signal that contributes to the development of PE. We hypothesized that TLR3/7/8 activation will be evident in placentas of women with PE, and sufficient to induce PE-like symptoms in mice. Placental immunoreactivity and mRNA levels of TLR3, TLR7, and TLR8 were increased significantly in women with PE compared to normotensive women. Treatment of human trophoblasts with the TLR3 agonist polyinosine-polycytidylic acid (poly I:C), the TLR7-specific agonist imiquimod (R-837), or the TLR7/8 agonist CLO97 significantly increased TLR3/7/8 levels. Treatment of mice with poly I:C, R-837, or CLO97 caused pregnancy-dependent hypertension, endothelial dysfunction, splenomegaly, and placental inflammation. These data demonstrate that RNA-mediated activation of TLR3 and TLR7/8 plays a key role in the development of PE.

Exposure of foetal neural progenitor cells to IL‐1β impairs their proliferation and alters their differentiation – a role for maternal inflammation?

During pregnancy, activation of the maternal immune system results in inflammation in the foetal nervous system. The causative agents are pro-inflammatory cytokines like interleukin-1β (IL-1β), produced by the foetus. In this study, we examine the effect of IL-1β on the proliferation and differentiation of neural progenitor cells (NPCs) to better understand its potential effects on the developing brain. We find that the IL-1β receptor (IL-1R1) is expressed in the ventral mesencephalon of the developing brain. Furthermore, IL-1R1 is expressed on Nestin-positive, Sox-2-positive NPCs. IL-1β treatment reduced the numbers of proliferating NPCs, an effect prevented by the IL-1R1 receptor antagonist. LDH and MTT assays, and western blot analysis for cleaved caspase 3 and poly(ADP-ribose) polymerase, confirmed that this was not due to an increase in cell death but rather an induction of differentiation. To further study the effects of IL-1β on cell fate determination, we differentiated NPCs in the presence and absence of IL-1β. Il-1β promoted gliogenesis and inhibited neurogenesis, an effect that required p38-MAPK kinase signalling. In summary, these data show that exposure of NPCs to IL-1β affects their development. This necessitates an examination of the consequences that maternal immune system activation during pregnancy has on the cellular architecture of the developing brain.

Interleukin 10 Deficiency Exacerbates Toll-Like Receptor 3–Induced Preeclampsia-Like Symptoms in Mice

Preeclampsia may result from overactivation of the maternal immune system and is characterized by endothelial dysfunction and excessive inflammation. Given the importance of maternal immune system regulation and anti-inflammatory cytokines in normotensive pregnancies, we hypothesized that maternal immune system activation via Toll-like receptor 3 during pregnancy would cause preeclampsia-like symptoms in mice, which would be made worse by deficiency of the anti-inflammatory cytokine interleukin 10. The Toll-like receptor 3 agonist polyinosine-polycytidylic acid (poly I:C) caused hypertension, endothelial dysfunction, and proteinuria in mice only when pregnant. In the absence of poly I:C, pregnant interleukin 10 knockout mice exhibited a significant increase in systolic blood pressure, endothelial dysfunction, and serum proinflammatory cytokines, as well as aortic and placental platelet-endothelial cell adhesion molecule expression compared with pregnant wild-type mice. Deficiency of interleukin 10 further augmented these measures in poly I:C-treated pregnant mice. In addition, sera from poly I:C-treated pregnant wild-type mice significantly decreased relaxation responses and increased platelet-endothelial cell adhesion molecule expression in isolated aortas from nonpregnant wild-type mice, and these effects were augmented by sera from poly I:C-treated interleukin 10 knockout mice. Coincubation with recombinant interleukin 10 normalized relaxation responses and platelet-endothelial cell adhesion molecule expression in all of the groups. Collectively, Toll-like receptor 3 activation during pregnancy causes preeclampsia-like symptoms, which are exacerbated by the absence of interleukin 10. Exogenous interleukin 10 treatment had beneficial effects on endothelial function and may be beneficial in women with preeclampsia.

Do double-stranded RNA receptors play a role in preeclampsia?

Dysregulation of the maternal immune system during pregnancy has been implicated in the development of preeclampsia (PE), however the pathogenetic signals and mechanisms have not been completely elucidated. Here we provide a hypothesis and evidence that dsRNA is a danger signal leading to maternal immune system activation and an “antiviral” immune response that manifests as PE. dsRNA released from necrotic cells and/or from viruses causes excessive activation of dsRNA receptors and PE-like symptoms in animals. Additionally, high expression levels of dsRNA receptors have been identified in human and animal placental tissue as well as trophoblast cells, and these receptors appear to be excessively activated in PE. These key components of the innate immune system that respond to invading pathogens and dead or necrotic tissue likely play a major role in the development of PE.

742: IL-4 KO mice exhibit gestational hypertension which is augmented following dsRNA-induced maternal immune system activation

Excessive maternal immune system activation and inflammation have been shown to play a major role in gestational hypertension (GH). Little is known about the role of the prototypical anti-inflammatory cytokine interleukin-4 (IL-4) in the development of GH. IL-4 KO mice have fairly normal pregnancies with respect to fetal development, however maternal blood pressure and endothelial function were not examined during normal pregnancy or in response to immune system activation during pregnancy.

Toll-Like Receptor 3 Activation During Pregnancy Elicits Preeclampsia-Like Symptoms in Rats

Preeclampsia (PE), a pregnancy-specific hypertensive syndrome, is one of the leading causes of premature births as well as fetal and maternal death. There is strong evidence that maternal immune system activation, of which Toll-like receptors (TLRs) play a major role, contributes to the development of PE. Viral infections, sensed by TLR3, are associated with hypertensive disorders of pregnancy. We tested the hypothesis that TLR3 activation during pregnancy would cause hypertension, endothelial dysfunction, proteinuria, and intrauterine growth restriction in normal pregnant rats. We treated pregnant and nonpregnant rats with the viral mimetic polyinosinic:polycytidylic acid (poly I:C) or vehicle every other day beginning at day 10 of gestation and measured systolic blood pressure, aortic vasodilation, urinary protein concentration, fetal growth, and serum and placental cytokine levels. Pregnant rats treated with poly I:C displayed significantly elevated systolic blood pressures compared to pregnant rats and nonpregnant rats treated with poly I:C on day 18 of gestation. Poly I:C-treated pregnant rats also exhibited significantly decreased aortic vasodilation, significantly increased urinary protein concentrations, and had more malformed pups/litter. Additionally, poly I:C-treated rats exhibited a significant increase in placental TLR3 expression and proinflammatory/anti-inflammatory cytokine ratio compared to vehicle-treated rats. Poly I:C treatment of nonpregnant control rats had no effect on systolic blood pressure, aortic vasodilation, or urinary protein concentrations. These findings demonstrate that sustained maternal immune system activation via TLR3 during pregnancy causes PE-like symptoms in rats and suggest that viral infection during pregnancy may contribute to the development of PE.