Complement inhibition and statins prevent fetal brain cortical abnormalities in a mouse model of preterm birth

Transplacental SARS-CoV-2 protein ORF8 binds to complement C1q to trigger fetal inflammation

Prenatal SARS-CoV-2 infection is associated with higher rates of pregnancy and birth complications, despite that vertical transmission rates are thought to be low. Here, multi-omics analyses of human placental tissues, cord tissues/plasma, and amniotic fluid from 23 COVID-19 mother-infant pairs revealed robust inflammatory responses in both maternal and fetal compartments. Pronounced expression of complement proteins (C1q, C3, C3b, C4, C5) and inflammatory cytokines (TNF, IL-1α, and IL-17A/E) was detected in the fetal compartment of COVID-19-affected pregnancies. While ~26% of fetal tissues were positive for SARS-CoV-2 RNA, more than 60% of fetal tissues contained SARS-CoV-2 ORF8 proteins, suggesting transplacental transfer of this viral accessory protein. ORF8-positive fetal compartments exhibited increased inflammation and complement activation compared to ORF8-negative COVID-19 pregnancies. In human placental trophoblasts in vitro, exogenous ORF8 exposure resulted in complement activation and inflammatory responses. Co-immunoprecipitation analysis demonstrated that ORF8 binds to C1q specifically by interacting with a 15-peptide region on ORF8 (C37-A51) and the globular domain of C1q subunit A. In conclusion, an ORF8-C1q-dependent complement activation pathway was identified in COVID-19-affected pregnancies, likely contributing to fetal inflammation independently of fetal virus exposure.

Elevated Adipsin and Reduced C5a Levels in the Maternal Serum and Follicular Fluid During Implantation Are Associated With Successful Pregnancy in Obese Women

INTRODUCTION

Complement factors mediate the recruitment and activation of immune cells and are associated with metabolic changes during pregnancy. The aim of this study was to determine whether complement factors in the maternal serum and follicular fluid (FF) are associated with in vitro fertilization (IVF) outcomes in overweight/obese women.

METHODS

Forty overweight/obese (BMI = 30.8 ± 5.2 kg/m²) female patients, 33.6 ± 6.3 years old, undergoing IVF treatment for unexplained infertility were recruited. Baseline demographic information, including biochemical hormonal, metabolic, and inflammatory markers, and pregnancy outcome, was collected. Levels of 14 complement markers (C2, C4b, C5, C5a, C9, adipsin, mannose-binding lectin, C1q, C3, C3b/iC3b, C4, factor B, factor H, and properdin) were assessed in the serum and FF and compared to IVF outcome, inflammatory, and metabolic markers using multivariate and univariate models.

RESULTS

Out of 40 IVF cycles, 14 (35%) resulted in pregnancy. Compared to women with failed pregnancies, women with successful pregnancies had higher levels of adipsin in the serum and FF (p = 0.01) but lower C5a levels (p = 0.05). Serum adipsin levels were positively correlated with circulating levels of vitamin D (R = 0.5, p = 0.02), glucagon (R = 0.4, p = 0.03), leptin (R = 0.4, p = 0.01), resistin (R = 0.4, p = 0.02), and visfatin (R = 0.4, p = 0.02), but negatively correlated with total protein (R = -0.5, p = 0.03). Higher numbers of top-quality embryos were associated with increased levels of C3, properdin, C1q, factors H and B, C4, and adipsin, but with reduced C2 and C5a levels (p ≤ 0.01).

CONCLUSIONS

Higher adipsin and lower C5a levels in the maternal serum during implantation are potential markers of successful outcome in obese women undergoing IVF-assisted pregnancies.

The cerebrospinal fluid proteome of preterm infants predicts neurodevelopmental outcome

BACKGROUND

Survival rate increases for preterm infants, but long-term neurodevelopmental outcome predictors are lacking. Our primary aim was to determine whether a specific proteomic profile in cerebrospinal fluid (CSF) of preterm infants differs from that of term infants and to identify novel biomarkers of neurodevelopmental outcome in preterm infants.

METHODS

Twenty-seven preterm infants with median gestational age 27 w + 4 d and ten full-term infants were enrolled prospectively. Protein profiling of CSF were performed utilizing an antibody suspension bead array. The relative levels of 178 unique brain derived proteins and inflammatory mediators, selected from the Human Protein Atlas, were measured.

RESULTS

The CSF protein profile of preterm infants differed from that of term infants. Increased levels of brain specific proteins that are associated with neurodevelopment and neuroinflammatory pathways made up a distinct protein profile in the preterm infants. The most significant differences were seen in proteins involved in neurodevelopmental regulation and synaptic plasticity, as well as components of the innate immune system. Several proteins correlated with favorable outcome in preterm infants at 18-24 months corrected age. Among the proteins that provided strong predictors of outcome were vascular endothelial growth factor C, Neurocan core protein and seizure protein 6, all highly important in normal brain development.

CONCLUSION

Our data suggest a vulnerability of the preterm brain to postnatal events and that alterations in protein levels may contribute to unfavorable neurodevelopmental outcome.

Immunological and physiopathological approach of COVID-19 in pregnancy

Coronavirus disease-2019 (COVID-19) related to Coronavirus-2 (SARS-CoV-2) is a worldwide health concern. Despite the majority of patients will evolve asymptomatic or mild-moderate upper respiratory tract infections, 20% will develop severe disease. Based on current pathogenetic knowledge, a severe COVID-19 form is mainly a hyperinflammatory, immune-mediated disorder, triggered by a viral infection. Due to their particular immunological features, pregnant women are supposed to be particularly susceptible to complicate by intracellular infections as well as immunological disturbances. As an example, immune-thrombosis has been identified as a common immune-mediated and pathogenic phenomenon both in COVID-19, in obstetric diseases and in COVID-19 pregnant women. According to extensive published clinical data, is rationale to expect an interference with the normal development of pregnancy in selected SARS-CoV-2-infected cases, mainly during third trimester.This manuscript provides insights of research to elucidate the potential harmful responses to SARS-CoV-2 and /or other coronavirus infections, as well as bidirectional interactions between COVID-19 and pregnancy to improve their respective management.

Ggps1 deficiency in the uterus results in dystocia by disrupting uterine contraction

Dystocia is a serious problem for pregnant women, and it increases the cesarean section rate. Although uterine dysfunction has an unknown etiology, it is responsible for cesarean delivery and clinical dystocia, resulting in neonatal morbidity and mortality; thus, there is an urgent need for novel therapeutic agents. Previous studies indicated that statins, which inhibit the mevalonate (MVA) pathway of cholesterol synthesis, can reduce the incidence of preterm birth, but the safety of statins for pregnant women has not been thoroughly evaluated. Therefore, to unambiguously examine the function of the MVA pathway in pregnancy and delivery, we employed a genetic approach by using myometrial cell-specific deletion of geranylgeranyl pyrophosphate synthase (Ggps1) mice. We found that Ggps1 deficiency in myometrial cells caused impaired uterine contractions, resulting in disrupted embryonic placing and dystocia. Studies of the underlying mechanism suggested that Ggps1 is required for uterine contractions to ensure successful parturition by regulating RhoA prenylation to activate the RhoA/Rock2/p-MLC pathway. Our work indicates that perturbing the MVA pathway might result in problems during delivery for pregnant females, but modifying protein prenylation with supplementary farnesyl pyrophosphate or geranylgeranyl pyrophosphate might be a strategy to avoid side effects.

Essential Role of Complement in Pregnancy: From Implantation to Parturition and Beyond

The complement cascade was identified over 100 years ago, yet investigation of its role in pregnancy remains an area of intense research. Complement inhibitors at the maternal-fetal interface prevent inappropriate complement activation to protect the fetus. However, this versatile proteolytic cascade also favorably influences numerous stages of pregnancy, including implantation, fetal development, and labor. Inappropriate complement activation in pregnancy can have adverse lifelong sequelae for both mother and child. This review summarizes the current understanding of complement activation during all stages of pregnancy. In addition, consequences of complement dysregulation during adverse pregnancy outcomes from miscarriage, preeclampsia, and pre-term birth are examined. Finally, future research directions into complement activation during pregnancy are considered.

Complement System in Brain Architecture and Neurodevelopmental Disorders

Current evidence indicates that certain immune molecules such as components of the complement system are directly involved in neurobiological processes related to brain development, including neurogenesis, neuronal migration, synaptic remodeling, and response to prenatal or early postnatal brain insults. Consequently, complement system dysfunction has been increasingly implicated in disorders of neurodevelopmental origin, such as schizophrenia, autism spectrum disorder (ASD) and Rett syndrome. However, the mechanistic evidence for a causal relationship between impaired complement regulation and these disorders varies depending on the disease involved. Also, it is still unclear to what extent altered complement expression plays a role in these disorders through inflammation-independent or -dependent mechanisms. Furthermore, pathogenic mutations in specific complement components have been implicated in the etiology of 3MC syndrome, a rare autosomal recessive developmental disorder. The aims of this review are to discuss the current knowledge on the roles of the complement system in sculpting brain architecture and function during normal development as well as after specific inflammatory insults, such as maternal immune activation (MIA) during pregnancy, and to evaluate the existing evidence associating aberrant complement with developmental brain disorders.

The role of complement in preterm birth and prematurity

Complications of preterm birth (PTB) are the global leading cause of death in children younger than 5 years of age. Almost 15 million children are born prematurely in the world each year. Increasing evidence suggests that labor and delivery have many hallmarks of an inflammatory reaction, where complement activation has an active participation. As one of the most important components of inflammation, the role of complement during labor and PTB is becoming an attractive research target. The complement components C1q and C5b-9 are deposited on fetal membranes and release inflammatory mediators that contribute to uterine contractions, cervical ripening, cell chemotaxis, metalloproteinases production, membrane awaking and rupture, and it participates as a co-adjuvant in the onset and progress of labor. This article reviews a basic description of the complement system, its role in preterm birth and current concepts regarding its contribution in novel therapy strategies and new biomarkers.

Repurposing simvastatin as a therapy for preterm labor: evidence from preclinical models

Preterm birth (PTB), the leading cause of neonatal morbidity and mortality, urgently requires novel therapeutic agents. Spontaneous PTB, resulting from preterm labor, is commonly caused by intrauterine infection/inflammation. Statins are well-established, cholesterol-lowering drugs that can reduce inflammation and inhibit vascular smooth muscle contraction. We show that simvastatin reduced the incidence of PTB in a validated intrauterine LPS-induced PTB mouse model, decreased uterine proinflammatory mRNA concentrations (IL-6, Cxcl1, and Ccl2), and reduced serum IL-6 concentration. In human myometrial cells, simvastatin reduced proinflammatory mediator mRNA and protein expression (IL-6 and IL-8) and increased anti-inflammatory cytokine mRNA expression (IL-10 and IL-13). Critically, simvastatin inhibited myometrial cell contraction, basally and during inflammation, and reduced phosphorylated myosin light chain concentration. Supplementation with mevalonate and geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, abolished these anticontractile effects, indicating that the Rho/Rho-associated protein kinase pathway is critically involved. Thus, simvastatin reduces PTB incidence in mice, inhibits myometrial contractions, and exhibits key anti-inflammatory effects, providing a rationale for investigation into the repurposing of statins to treat preterm labor in women.—Boyle, A. K., Rinaldi, S. F., Rossi, A. G., Saunders, P. T. K., Norman, J. E. Repurposing simvastatin as a therapy for preterm labor: evidence from preclinical models.

The Cerebrospinal Fluid Inflammatory Response to Preterm Birth

Background: Preterm birth is the leading risk factor for perinatal white matter injury, which can lead to motor and neuropsychiatric impairment across the life course. There is an unmet clinical need for therapeutics. White matter injury is associated with an altered inflammatory response in the brain, primarily led by microglia, and subsequent hypomyelination. However, microglia can release both damaging and trophic factors in response to injury, and a comprehensive assessment of these factors in the preterm central nervous system (CNS) has not been carried out.

Method: A custom antibody array was used to assess relative levels of 50 inflammation- and myelination-associated proteins in the cerebrospinal fluid (CSF) of preterm infants in comparison to term controls.

Results: Fifteen proteins differed between the groups: BDNF, BTC, C5a, FasL, Follistatin, IL-1β, IL-2, IL-4, IL-9, IL-17A, MIP-1α, MMP8, SPP1, TGFβ, and TNFβ (p < 0.05). To investigate the temporal regulation of these proteins after injury, we mined a gene expression dataset of microglia isolated from a mouse model of developmental white matter injury. Microglia in the experimental model showed dynamic temporal expression of genes encoding these proteins, with an initial and sustained pro-inflammatory response followed by a delayed anti-inflammatory response, and a continuous expression of genes predicted to inhibit healthy myelination.

Conclusion: Preterm CSF shows a distinct neuroinflammatory profile compared to term controls, suggestive of a complex neural environment with concurrent damaging and reparative signals. We propose that limitation of pro-inflammatory responses, which occur early after perinatal insult, may prevent expression of myelination-suppressive genes and support healthy white matter development.

Pravastatin alleviates lipopolysaccharide-induced placental TLR4 over-activation and promotes uterine arteriole remodeling without impairing rat fetal development

Preeclampsia is associated with over-activation of the innate immune system in the placenta, in which toll-like receptor 4 (TLR4) plays an essential part. With their potent anti-inflammatory effects, statins have been suggested as potential prevention or treatment of preeclampsia, although evidence remains inadequate. Herewith, we investigated whether pravastatin could ameliorate preeclampsia-like phenotypes in a previously established lipopolysaccharide (LPS)-induced rat preeclampsia model, through targeting the TLR4/NF-κB pathway. The results showed that pravastatin reduced the blood pressure [maximum decline on gestational day (GD) 12, (101.33±2.49) mmHg vs. (118.3±1.37) mmHg, P<0.05] and urine protein level [maximum decline on GD9, (3,726.23±1,572.86)μg vs. (1,991.03±609.37)μg, P<0.05], which were elevated following LPS administration. Pravastatin also significantly reduced the rate of fetal growth restriction in LPS-treated rats (34.10% vs. 8.99%, P<0.05). Further pathological analyses suggested a restoration of normal spiral artery remodeling in preeclampsia rats by pravastatin treatment. These effects of pravastatin were associated with decreased TLR4/NF-κB protein levels in the placenta and IL-6/MCP-1 levels in serum. Additionally, no obvious abnormalities in fetal liver, brain, and kidney were found after administration of pravastatin. These results provide supportive evidence for use of pravastatin in preventing preeclampsia.

Complement activation, a threat to pregnancy

Pregnancy poses a challenge for the immune systems of placental mammals. As fetal tissues are semi-allogeneic and alloantibodies that commonly develop in the mother, the fetus and the placenta might be subject to complement-mediated immune attack with the potential risk of adverse pregnancy outcomes. Here, I describe how the use of animal models was pivotal in demonstrating that complement inhibition at the fetomaternal interface is essential for a successful pregnancy. Studies in animals also helped the identification of uncontrolled complement activation as a crucial effector in the pathogenesis of recurrent miscarriages, intrauterine growth restriction, preeclampsia, and preterm birth. Clinical studies employing complement biomarkers in plasma and urine showed an association between dysregulation of the complement system and adverse pregnancy outcomes. A better understanding of the role of the complement system in pregnancy complications will allow a rational approach to manipulate its activation as a potential therapeutic strategy with the goal of protecting pregnancies and improving long-term outcomes for mother and child.

Complement C5a is present in CSF of human newborns and is elevated in association with preterm birth

Neuroinflammation contributes to developmental brain injury associated with preterm birth, but the mediators that drive it are incompletely understood. Previous studies have shown that complement C5a is present and injurious in the brains of foetal mice exposed to preterm labour. Here, we demonstrate that C5a is present in the cerebrospinal fluid of newborn human infants and that levels are elevated in those born preterm. The difference is not explained by systemic infection. Complement activation in the neonatal brain and its role as a potential therapeutic target in preterm brain injury warrant further study. Activation in the neonatal brain and its role as a potential therapeutic target for preterm brain injury warrants further study.

Simvastatin prevents and reverses chronic pulmonary hypertension in newborn rats via pleiotropic inhibition of RhoA signaling

Chronic neonatal pulmonary hypertension (PHT) frequently results in early death. Systemically administered Rho-kinase (ROCK) inhibitors prevent and reverse chronic PHT in neonatal rats, but at the cost of severe adverse effects, including systemic hypotension and growth restriction. Simvastatin has pleiotropic inhibitory effects on isoprenoid intermediates that may limit activity of RhoA, which signals upstream of ROCK. We therefore hypothesized that statin treatment would safely limit pulmonary vascular RhoA activity and prevent and reverse experimental chronic neonatal PHT via downstream inhibitory effects on pathological ROCK activity. Sprague-Dawley rats in normoxia (room air) or moderate normobaric hypoxia (13% O2) received simvastatin (2 mg·kg−1·day−1 ip) or vehicle from postnatal days 1–14 (prevention protocol) or from days 14–21 (rescue protocol). Chronic hypoxia increased RhoA and ROCK activity in lung tissue. Simvastatin reduced lung content of the isoprenoid intermediate farnesyl pyrophosphate and decreased RhoA/ROCK signaling in the hypoxia-exposed lung. Preventive or rescue treatment of chronic hypoxia-exposed animals with simvastatin decreased pulmonary vascular resistance, right ventricular hypertrophy, and pulmonary arterial remodeling. Preventive simvastatin treatment improved weight gain, did not lower systemic blood pressure, and did not cause apparent toxic effects on skeletal muscle, liver or brain. Rescue therapy with simvastatin improved exercise capacity. We conclude that simvastatin limits RhoA/ROCK activity in the chronic hypoxia-exposed lung, thus preventing or ameliorating hemodynamic and structural markers of chronic PHT and improving long-term outcome, without causing adverse effects.

Histological chorioamnionitis shapes the neonatal transcriptomic immune response

BACKGROUND

Histologic chorioamnionitis (HCA) is commonly associated with preterm birth and deleterious post-natal outcomes including sepsis and necrotizing enterocolitis. Transcriptomic analysis has been used to uncover gene signatures that permit diagnosis and prognostication, show new therapeutic targets, and reveal mechanisms that underlie differential outcomes with other complex disease states in neonates such as sepsis.

AIMS

To define the transcriptomic and inflammatory protein response in peripheral blood among infants with exposure to histologic chorioamnionitis.

STUDY DESIGN

Prospective, observational study.

SUBJECTS

Uninfected preterm neonates retrospectively categorized based on placental pathology with no HCA exposure (n=18) or HCA exposure (n=15).

OUTCOMES MEASURES

We measured the transcriptomic and inflammatory mediator response in prospectively collected whole blood.

RESULTS

We found 488 significant (p<0.001), differentially expressed genes in whole blood samples among uninfected neonates with HCA exposure that collectively represented activated innate and adaptive immune cellular pathways and revealed a potential regulatory role for the pleotropic microRNA molecule miR-155. Differentially secreted plasma cytokines in patients with HCA exposure compared to patients without HCA included MCP-1, MPO, and MMP-9 (p<0.05).

CONCLUSIONS

Exposure to HCA distinctively activates the neonatal immune system in utero with potentially long-term health consequences.

Simvastatin improves the homing of BMSCs via the PI3K/AKT/miR-9 pathway

Bone marrow‐derived mesenchymal stem cells (BMSCs) have great therapeutic potential for many diseases. However, the homing of BMSCs to injury sites remains a difficult problem. Recent evidence indicates that simvastatin stimulates AKT phosphorylation, and p‐AKT affects the expression of chemokine (CXC motif) receptor‐4 (CXCR4). Therefore, simvastatin may improve the expression of CXCR4 in BMSCs, and microRNAs (miRs) may participate in this process. In this study, we demonstrated that simvastatin increased both the total and the surface expression of CXCR4 in BMSCs. Stromal cell‐derived factor‐1α (SDF‑1α)‐induced migration of BMSCs was also enhanced by simvastatin, and this action was inhibited by AMD 3100(a chemokine receptor antagonist for CXCR4). The PI3K/AKT pathway was activated by simvastatin in this process, and LY294002 reversed the overexpression of CXCR4 caused by simvastatin. MiR‐9 directly targeted CXCR4 in rat BMSCs, and simvastatin decreased miR‐9 expression. P‐AKT affected the expression of miR‐9; as the phosphorylation of AKT increased, miR‐9 expression decreased. In addition, LY294002 increased miR‐9 expression. Taken together, our results indicated that simvastatin improved the migration of BMSCs via the PI3K/AKT pathway. MiR‐9 also participated in this process, and the phosphorylation of AKT affected miR‐9 expression, suggesting that simvastatin might have beneficial effects in stem cell therapy.

Complement Activation in Placental Malaria

Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.

Longitudinal in vivo maturational changes of metabolites in the prefrontal cortex of rats exposed to polyinosinic-polycytidylic acid in utero

Proton magnetic resonance spectroscopy ((1)H MRS) studies in schizophrenia patients generally report decreased levels of N-acetyl-aspartate (NAA), glutamate and glutathione, particularly in frontal cortex. However, these data are inconsistent in part due to confounds associated with clinical samples. The lack of validated diagnostic biomarkers also hampers analysis of the neurodevelopmental trajectory of neurochemical abnormalities. Rodent models are powerful tools to address these issues, particularly when combined with (1)H MRS (clinically comparable technology). We investigated the trajectory of metabolic changes in the prefrontal cortex during brain maturation from adolescence to adulthood in vivo using (1)H MRS in rats exposed prenatally to polyinosinic-polycytidylic acid (POL), a rodent model of maternal immune activation (MIA), an epidemiological risk factor for several psychiatric disorders with a neurodevelopmental origin. Longitudinal in vivo (1)H MRS revealed a significant decrease in PFC levels of GSH and taurine in adult, but not adolescent rats. Significant age×MIA interactions for PFC levels of NAA were also observed. These data replicate some deficits observed in the PFC of patients with schizophrenia. There were no significant changes in the levels of glutamate or any other metabolite. These data suggest prenatal exposure to POL leads to subtle metabolic perturbations of the normal maturing PFC, which may be related to subsequent behavioural abnormalities. Further work is however required to examine any potential confound of shipping stress on the presumed imbalances in PFC metabolites in POL-exposed offspring. Testing the interactions between MIA with stress or genetic risk variants will also be an important advance.

Experimental Malaria in Pregnancy Induces Neurocognitive Injury in Uninfected Offspring via a C5a-C5a Receptor Dependent Pathway

The in utero environment profoundly impacts childhood neurodevelopment and behaviour. A substantial proportion of pregnancies in Africa are at risk of malaria in pregnancy (MIP) however the impact of in utero exposure to MIP on fetal neurodevelopment is unknown. Complement activation, in particular C5a, may contribute to neuropathology and adverse outcomes during MIP. We used an experimental model of MIP and standardized neurocognitive testing, MRI, micro-CT and HPLC analysis of neurotransmitter levels, to test the hypothesis that in utero exposure to malaria alters neurodevelopment through a C5a-C5aR dependent pathway. We show that malaria-exposed offspring have persistent neurocognitive deficits in memory and affective-like behaviour compared to unexposed controls. These deficits were associated with reduced regional brain levels of major biogenic amines and BDNF that were rescued by disruption of C5a-C5aR signaling using genetic and functional approaches. Our results demonstrate that experimental MIP induces neurocognitive deficits in offspring and suggest novel targets for intervention.

A growing body of evidence has established the importance of the in utero environment on neurodevelopment and long-term cognitive and behavioral outcomes. These data suggest factors that disrupt the tightly regulated in utero environment can modify normal neurodevelopmental processes. Approximately 125 million pregnancies worldwide are at risk of malaria infection every year. However the impact of in utero exposure to MIP on fetal neurodevelopment is unknown. Here we use a mouse model of malaria in pregnancy to examine the impact of maternal malaria exposure on neurocognitive outcomes in offspring. We observed impaired learning and memory and depressive-like behavior in malaria-exposed offspring that were neither congenitally infected nor low birth weight. These neurocognitive impairments were associated with decreased tissue levels of neurotransmitters in regions of the brain linked to the observed deficits. Disruption of maternal C5a complement receptor signaling restored the levels of neurotransmitters and rescued the associated cognitive phenotype observed in malaria-exposed offspring. This study provides the first evidence implicating a causal link between pre-natal exposure to malaria, complement signaling and subsequent neurocognitive impairment in offspring.

Imaging of activated complement using ultrasmall superparamagnetic iron oxide particles (USPIO)--conjugated vectors: an in vivo in utero non-invasive method to predict placental insufficiency and abnormal fetal brain development

In the current study, we have developed a magnetic resonance imaging-based method for non-invasive detection of complement activation in placenta and foetal brain in vivo in utero. Using this method, we found that anti-complement C3-targeted ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles bind within the inflamed placenta and foetal brain cortical tissue, causing a shortening of the T2* relaxation time. We used two mouse models of pregnancy complications: a mouse model of obstetrics antiphospholipid syndrome (APS) and a mouse model of preterm birth (PTB). We found that detection of C3 deposition in the placenta in the APS model was associated with placental insufficiency characterised by increased oxidative stress, decreased vascular endothelial growth factor and placental growth factor levels and intrauterine growth restriction. We also found that foetal brain C3 deposition was associated with cortical axonal cytoarchitecture disruption and increased neurodegeneration in the mouse model of APS and in the PTB model. In the APS model, foetuses that showed increased C3 in their brains additionally expressed anxiety-related behaviour after birth. Importantly, USPIO did not affect pregnancy outcomes and liver function in the mother and the offspring, suggesting that this method may be useful for detecting complement activation in vivo in utero and predicting placental insufficiency and abnormal foetal neurodevelopment that leads to neuropsychiatric disorders.

Heme oxygenase and the immune system in normal and pathological pregnancies

Normal pregnancy is an immunotolerant state. Many factors, including environmental, socioeconomic, genetic, and immunologic changes by infection and/or other causes of inflammation, may contribute to inter-individual differences resulting in a normal or pathologic pregnancy. In particular, imbalances in the immune system can cause many pregnancy-related diseases, such as infertility, abortions, pre-eclampsia, and preterm labor, which result in maternal/fetal death, prematurity, or small-for-gestational age newborns. New findings imply that myeloid regulatory cells and regulatory T cells (Tregs) may mediate immunotolerance during normal pregnancy. Effector T cells (Teffs) have, in contrast, been implicated to cause adverse pregnancy outcomes. Furthermore, feto-maternal tolerance affects the developing fetus. It has been shown that the Treg/Teff balance affects litter size and adoptive transfer of pregnancy-induced Tregs can prevent fetal rejection in the mouse. Heme oxygenase-1 (HO-1) has a protective role in many conditions through its anti-inflammatory, anti-apoptotic, antioxidative, and anti-proliferative actions. HO-1 is highly expressed in the placenta and plays a role in angiogenesis and placental vascular development and in regulating vascular tone in pregnancy. In addition, HO-1 is a major regulator of immune homeostasis by mediating crosstalk between innate and adaptive immune systems. Moreover, HO-1 can inhibit inflammation-induced phenotypic maturation of immune effector cells and pro-inflammatory cytokine secretion and promote anti-inflammatory cytokine production. HO-1 may also be associated with T-cell activation and can limit immune-based tissue injury by promoting Treg suppression of effector responses. Thus, HO-1 and its byproducts may protect against pregnancy complications by its immunomodulatory effects, and the regulation of HO-1 or its downstream effects has the potential to prevent or treat pregnancy complications and prematurity.

The role of inflammation in perinatal brain injury

Inflammation is increasingly recognized as being a critical contributor to both normal development and injury outcome in the immature brain. The focus of this Review is to highlight important differences in innate and adaptive immunity in immature versus adult brain, which support the notion that the consequences of inflammation will be entirely different depending on context and stage of CNS development. Perinatal brain injury can result from neonatal encephalopathy and perinatal arterial ischaemic stroke, usually at term, but also in preterm infants. Inflammation occurs before, during and after brain injury at term, and modulates vulnerability to and development of brain injury. Preterm birth, on the other hand, is often a result of exposure to inflammation at a very early developmental phase, which affects the brain not only during fetal life, but also over a protracted period of postnatal life in a neonatal intensive care setting, influencing critical phases of myelination and cortical plasticity. Neuroinflammation during the perinatal period can increase the risk of neurological and neuropsychiatric disease throughout childhood and adulthood, and is, therefore, of concern to the broader group of physicians who care for these individuals.

The complement system and adverse pregnancy outcomes

Adverse pregnancy outcomes significantly contribute to morbidity and mortality for mother and child, with lifelong health consequences for both. The innate and adaptive immune system must be regulated to insure survival of the fetal allograft, and the complement system is no exception. An intact complement system optimizes placental development and function and is essential to maintain host defense and fetal survival. Complement regulation is apparent at the placental interface from early pregnancy with some degree of complement activation occurring normally throughout gestation. However, a number of pregnancy complications including early pregnancy loss, fetal growth restriction, hypertensive disorders of pregnancy and preterm birth are associated with excessive or misdirected complement activation, and are more frequent in women with inherited or acquired complement system disorders or complement gene mutations. Clinical studies employing complement biomarkers in plasma and urine implicate dysregulated complement activation in components of each of the adverse pregnancy outcomes. In addition, mechanistic studies in rat and mouse models of adverse pregnancy outcomes address the complement pathways or activation products of importance and allow critical analysis of the pathophysiology. Targeted complement therapeutics are already in use to control adverse pregnancy outcomes in select situations. A clearer understanding of the role of the complement system in both normal pregnancy and complicated or failed pregnancy will allow a rational approach to future therapeutic strategies for manipulating complement with the goal of mitigating adverse pregnancy outcomes, preserving host defense, and improving long term outcomes for both mother and child.

Ultrasound-guided intrauterine injection of lipopolysaccharide as a novel model of preterm birth in the mouse

Mouse models are used to study mechanisms that link intrauterine infection and preterm birth (PTB). To mimic intrauterine infection, lipopolysaccharide (LPS) is commonly injected into the uterus via minilaparotomy, which is invasive, and can cause PTB in control animals. We hypothesized that less-invasive ultrasound-guided intrauterine LPS injection or intravaginal LPS administration could induce PTB by stimulating an inflammatory response of the uteroplacental tissues, while minimizing PTB in control animals. On day 17 of gestation mice received LPS intravaginally (10 to 240 μg; n = 3 to 8) or into the uterus (20 μg) under ultrasound guidance (n = 7) or via laparotomy (n = 7). Control animals received phosphate-buffered saline (PBS; n = 5 to 7). Intrauterine administration of LPS, both under ultrasound guidance and via laparotomy, induced delivery earlier than in PBS control groups (P < 0.01). Intravaginal LPS administration did not stimulate PTB. Quantitative real-time PCR and immunohistochemistry of tissues harvested 6 hours after treatment confirmed that ultrasound-guided LPS administration induced a localized inflammatory response. Ultrasound-guided intrauterine LPS injection reliably induces PTB in the mouse and mimics the local inflammatory and immune responses observed in the more-invasive laparotomy model of inflammation-induced PTB. Ultrasound-guided intrauterine LPS injection is a useful novel model of PTB for future studies and concords with the principles of reduction, replacement, and refinement.

Thyroid hormone-dependent epigenetic suppression of herpes simplex virus-1 gene expression and viral replication in differentiated neuroendocrine cells

A global HSV-1 gene repression occurs during latency in sensory neurons where most viral gene transcriptions are suppressed. The molecular mechanisms of gene silencing and how stress factors trigger the reactivation are not well understood. Thyroid hormones are known to be altered due to stress, and with its nuclear receptor impart transcriptional repression or activation depending upon the hormone level. Therefore we hypothesized that triiodothyronine (T3) treatment of infected differentiated neuron like cells would reduce the ability of HSV-1 to produce viral progeny compared to untreated infected cells. Previously we identified putative thyroid hormone receptor elements (TREs) within the promoter regions of HSV-1 thymidine kinase (TK) and other key genes. Searching for a human cell line that can model neuronal HSV-1 infection, we performed HSV-1 infection experiments on differentiated human neuroendocrine cells, LNCaP. Upon androgen deprivation these cells undergo complete differentiation and exhibit neuronal-like morphology and physiology. These cells were readily infected by our HSV-1 recombinant virus, expressing GFP and maintaining many processes iconic of dendritic morphology. Our results demonstrated that differentiated LNCaP cells produced suppressive effects on HSV-1 gene expression and replication compared to its undifferentiated counterpart and T3 treatment has further decreased the viral plaque counts compared to untreated cells. Upon washout of the T3 viral plaque counts were restored, indicating an increase of viral replication. The qRT-PCR experiments using primers for TK showed reduced expression under T3 treatment. ChIP assays using a panel of antibodies for H3 lysine 9 epigenetic marks showed increased repressive marks on the promoter regions of TK. In conclusion we have demonstrated a T3 mediated quiescent infection in differentiated LNCaP cells that has potential to mimic latent infection. In this HSV-1 infection model thyroid hormone treatment caused decreased viral replication, repressed TK expression and increased repressive histone tail marks on the TK promoter.

Statins prevent cervical remodeling, myometrial contractions and preterm labor through a mechanism that involves hemoxygenase-1 and complement inhibition

Preterm birth (PTB) is a major public health problem, with a global prevalence of 9.6% and over a million annual neonatal deaths. In a mouse model of preterm labor (PTL) induced by intravaginal administration of a subclinical dose of lipopolysaccharide (LPS), we previously demonstrated that LPS ascends to the cervix, inducing complement activation, cervical remodeling and PTL. Here we show that complement activation also plays a role in myometrial contractions during PTL in this model. Increased levels of C5a were detected in the myometrium of LPS-treated mice but not in age-matched control or term myometrium. Human and mouse myometrium incubated with C5a showed increased frequency of contractions and expression of connexin 43, suggesting that C5a is an uterotonic molecule. Statins, which showed beneficial effects in preventing complement-mediated pregnancy complications, prevented cervical remodeling, myometrial contractions and PTL in the LPS model. The protective effects of statins in PTL were associated with increased synthesis, expression and activity of heme oxygenase (HO-1) in myometrium and cervix. Coadministration of HO-1 inhibitor tin-protoporphyrin-IX with pravastatin abrogated the protective effects of pravastatin on cervical remodeling and myometrial contractions leading to PTB. In addition, pravastatin inhibited complement activation in the cervix by increasing the synthesis and expression of complement inhibitor decay-accelerating factor. This study in mice suggests that statins might be useful to prevent PTL in humans. Clinical trials in humans are needed and if these results are confirmed, they may form the basis for a new clinical approach to prevent PTB.

Modulators of complement activation: a patent review (2008 - 2013)

INTRODUCTION

The architecture of the complement system has evolved during the last 600 - 700 million years to become an amazingly efficient and highly versatile alerting and cell killing device. Under physiological conditions, this system acts as a well-regulated cascade, protecting the organism against pathogens and participating during the initial defensive steps of humoral and cellular response. The unregulated activation of this system may cause or even aggravate diseases; therefore, its modulation is currently considered of high importance.

AREAS COVERED

This review is a critical examination on patent literature published between 2008 and 2013. An insight is provided about the discovery and development of novel therapeutic agents. These include macromolecules, polysaccharides and proteins, specific antibodies, and hybrid or chimeric products. Peptides and low molecular weight organic compounds (natural products, their derivatives and fully synthetic molecules) are covered as well.

EXPERT OPINION

The search of specific inhibitors of the complement cascade has become one of the Holy Grails of Medicinal Chemistry for the last 30 - 40 years, with very few cases of success. Some highly specific macromolecules are currently available as modulators of the complement. However, there is still a marked need to find new, more specific, efficient and convenient alternatives, especially suited for chronic administration, including novel inexpensive small molecule inhibitors. Analogously, despite the initial success with specific monoclonal antibodies, a vast territory is awaiting to be explored and conquered, regarding the regulation of complement activation by antibody-mediated blockage of specific polypeptides or receptor sites.