Ecology of danger-dependent cytokine-boosted spontaneous abortion in the CBA x DBA/2 mouse model: II. Fecal LPS levels in colonies with different basal abortion rates

Inflammatory conditions promote a switch of oligosaccharyltransferase (OST) catalytic subunit isoform expression

Oligosaccharyltransferase (OST) complex catalyzes the N-glycosylation of nascent polypeptides in the endoplasmic reticulum. Glycoproteins are critical for normal cell-cell interactions, especially during an immune response. Abnormal glycosylation is an insignia of several inflammatory diseases. However, the mechanisms that regulate the differential N-glycosylation are not fully understood. The OST complex can be assembled with one out of two catalytic subunits, STT3A or STT3B, which have different enzymatic properties. In this work, we investigated the expression of STT3A and STT3B in several mouse models such as a crossbreeding of normal and abortion-prone mice and an intestinal inflammation model. These animals were either exposed or not to acoustic stress (acute or chronic). The expression of the isoforms was analysed by immunohistochemistry and protein immunoblot. Finally, we investigated the gene regulatory elements employing public databases. Results demonstrated that inflammation alters the balance between the expression of both isoforms in the affected tissues. In homoeostatic conditions, STT3A expression predominates over STT3B, especially in epithelial cells. This relation is reversed as a consequence of inflammation. An increase in STT3B activity was associated to the generation of mannose-rich N-glycans. Accordingly, this type of N-glycans were found to decorate diverse inflamed tissues. The STT3A and STT3B genes are differentially regulated, which could account for the differences in the expression levels observed here. Our results support the idea that these isoforms could play different roles in cellular physiology. This study opens the possibility of studying the STT3A/STT3B expression ratio as a biomarker in acute inflammation or chronic diseases.

Intravenously Injected Pluripotent Stem Cell-derived Cells Form Fetomaternal Vasculature and Prevent Miscarriage in Mouse

Miscarriage is the most common complication of pregnancy, and about 1% of pregnant women suffer a recurrence. Using a widely used mouse miscarriage model, we previously showed that intravenous injection of bone marrow (BM)-derived endothelial progenitor cells (EPCs) may prevent miscarriage. However, preparing enough BM-derived EPCs to treat a patient might be problematic. Here, we demonstrated the generation of mouse pluripotent stem cells (PSCs), propagation of sufficient PSC-derived cells with endothelial potential (PSC-EPs), and intravenous injection of the PSC-EPs into the mouse miscarriage model. We found that the injection prevented miscarriage. Three-dimensional reconstruction images of the decidua after tissue cleaning revealed robust fetomaternal neovascularization induced by the PSC-EP injection. Additionally, the injected PSC-EPs directly formed spiral arteries. These findings suggest that intravenous injection of PSC-EPs could become a promising remedy for recurrent miscarriage.

Expression of Toll-like receptors and costimulatory molecules in splenic B cells in a normal and abortion-prone murine pregnancy model

PROBLEM

The regulatory role of B lymphocytes in the pregnancy-induced maternal immune response is not well recognized. B lymphocytes function as antigen-presenting cells (APCs) and regulate Toll-like receptors and costimulatory molecule expression in response to intrinsic and extrinsic signals. Therefore, the aim of this study was to determine the expression of TLR2, TLR4, TLR9, and MHC class II and the costimulatory molecules CD80, CD86, and CD40 in splenic B cells in a normal and abortion-prone murine pregnancy model.

METHODS OF STUDY

The expression level of these molecules on female splenic B cells was investigated using real-time PCR and flow cytometry. The analysis was performed on the 3rd and 14th day of normal (CBA/JxBALB/c) and abortion-prone (CBA/JxDBA/2J) murine pregnancy.

RESULTS

The expression of Tlr9, Cd86, and H2-Ab1 in splenic B cells on the 3rd day after mating was upregulated, whereas Tlr2 was downregulated in abortion-prone females. On day 14, we observed lower expression levels of Tlr4 and Cd80 and higher expression levels of Cd86 in CBA/J females mated with DBA/2J males. At the protein level, the differences were observed only on day 3 of pregnancy. TLR4 and CD40 molecules were upregulated in splenic B cells, while TLR9 and CD86 were downregulated in abortion-prone mice.

CONCLUSION

Differential expression of TLRs and costimulatory molecules in splenic B cells in abortion-prone and normal pregnancies suggests the involvement of these cells in the regulation of the immune response at the periphery in pregnant females.

A unified (but in fact not fully testable) model of preeclampsia triggering

In this summary of my presentation in the last Reunion workshop I discuss a few assertions on preeclampsia, then turn on a (not fully testable) model where an embryonic defect in expression of embryo/ placental regulatory proteins results in complement activation, itself responsible for a down regulation of the T regs activity, resulting in a very early lack of complete down regulation of the preimplantation decidual inflammation, causing in the post implantation stage a low grade but chronic inflammatory state.

Recombinant human soluble thrombomodulin as an anticoagulation therapy improves recurrent miscarriage and fetal growth restriction due to placental insufficiency - The leading cause of preeclampsia

INTRODUCTION

Placental insufficiency is one of the major risk factors for growth restriction and preeclampsia. The aim of this study is to investigate whether recombinant human Thrombomodulin(r-TM) improves fetal conditions and physiological outcomes.

METHODS

We used CBA/J × BALB/C mice as a control and CBA/J × DBA/2 mice - a well-studied model of recurrent spontaneous miscarriage. Pregnant mice received daily subcutaneous injections of r-TM or saline from day 0-15. The fetal resorption rate, fetal weight, and litter size were calculated at day 15. Additionally, we analyzed the mRNA expression of angiogenic factors and the concentration of soluble Flt-1 (sFlt-1) using the ELISA kit.

RESULTS

The rate of fetal resorption in CBA/J × DBA/2 mice treated with r-TM was significantly lower compared with mice without r-TM treatment. Additionally, fetal weight and litter size were also significantly higher in the r-TM treated mice. Fibrinogen deposition in the labyrinth area of the CBA/J × DBA/2 mice treated with r-TM was significantly lower compared with deposits in the mice untreated with r-TM. As well, r-TM significantly increased the gene expression level of VEGF and Flt-1 mRNA in the placentas of the CBA/J × DBA/2 mice. r-TM treatment also significantly decreased the production of sFlt-1 protein in the placentas of preeclampsia-like diseased mice.

CONCLUSION

r-TM as an anticoagulation therapy has the potential for the medical treatment of recurrent miscarriage and fetal growth restriction due to improved angiogenic factors. Additionally, r-TM treatment has the potential for the recovery of preeclampsia.

IL-17 Induces Fetal Loss in a CBA/J×BALB/c Mouse Model, and an Anti-IL-17 Antibody Prevents Fetal Loss in a CBA/J×DBA/2 Mouse Model

PROBLEM

Many researchers have demonstrated that the expression of interleukin-17(IL-17) is higher in spontaneous abortion. However, whether Th17 cells are an independent factor in inducing abortion is not known.

METHOD OF STUDY

This study investigated the effect of exogenous recombinant IL-17 and an anti-IL-17 antibody in a normal and an abortion mouse model using flow cytometry, enzyme-linked immunosorbent assay, real-time PCR, and Western blot.

RESULTS

Th17 cells and the related factors, IL-17 and RORγt, were significantly upregulated in abortion mice, and Treg cells and the related factor, Foxp3, were downregulated. Intraperitoneal injection of recombinant IL (rIL)-17 induced fetal loss in a normal mouse model, and an anti-IL-17 antibody prevented fetal loss in an abortion mouse model.

CONCLUSION

This study confirmed an imbalance of the Th17/Treg paradigm in abortion mice and IL-17 as a risk factor of fetal loss. An anti-IL-17 antibody may prevent abortion.

The Role of C5a Receptor Signaling in Endotoxin-Induced Miscarriage and Preterm Birth

PROBLEM

Complement factor 5a (C5a), a potent pro-inflammatory mediator of the complement system, has been implicated in fetal rejection throughout gestation, from miscarriage to preterm birth. This study aimed to investigate the role of the principal C5a receptor, C5aR1 (CD88), in both miscarriage and preterm birth, in a bacterial endotoxin (lipopolysaccharide; LPS) murine model.

METHOD OF STUDY

Wild-type and C5ar1 knockout mice were administered LPS at 9.5 or 15.5 days post-conception to induce miscarriage or preterm birth, respectively.

RESULTS

C5ar1 knockout mice were protected against miscarriage in response to administration of LPS in early gestation. However, the absence of C5aR1 had no effect on the rates of preterm birth when LPS was administered in late gestation.

CONCLUSION

There may be a gestational window in which excessive activation of C5a can exert deleterious effects in pregnancy. Future strategies targeting the C5a-C5aR1 signaling axis should be considered to ameliorate miscarriages in patients with recurrent pregnancy loss.

Comparative analysis of gut microbiota in elderly people of urbanized towns and longevity villages

Background

To understand differences in the gut microbiota between elderly people of urbanized town communities (UTC) and longevity village communities (LVC), we analyzed fecal microbiota collected from individuals living in 2 UTC (Seoul and Chuncheon) and 3 LVC (Gurye, Damyang, and Soonchang) selected on the basis of indices for superlongevity (the ratio of centenarians to the total population) and longevity (the ratio of those aged 85 years or greater to those aged 65 years or greater) in South Korea by 454 pyrosequencing.

Results

Taxonomy-based analysis showed that The relative abundance of Firmicutes, Tenericutes, and Actinobacteria was significantly lower in LVC than in UTC. Due to an increase of Firmicutes and a reduction of Bacteroidetes, the ratio of Firmicutes to Bacteroidetes in the gut microbiota was greater in UTC adults than in UTC children or LVC adults. The population levels of Bacteroides, Prevotella, and Lachnospira were significantly higher in LVC than in UTC, but the levels of Dialister, Subdoligranulum, Megamonas, EF401882_g, and AM275436_g were lower in LVC than in UTC. Although most of the species detected in LVC were detected in UTC, some Bacteroides spp. and Faecalibacterium spp. were detected only in LVC. Among Bacteroides spp., ACWH_s, EF403317_s, and EF403722_s were detected in children and LVC samples only but FJ363527_s, 4P000677_s, and 4P000015_s were detected in UTC samples. EF402172_s and EF404388_s, members of Faecalibacterium spp., which are known to have anti-inflammatory properties, were detected in LVC and children only (>3.9% of total sequence). In addition, the fecal lipopolysaccharides (LPS) content was significantly higher in UTC than in LVC.

Conclusions

These findings suggest that maintaining gut microbiota, including Faecalibacterium spp. EF402172_s and EF404388_s, as well as low LPS levels may play an important role in preserving residents’ health in LVC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0386-8) contains supplementary material, which is available to authorized users.

Inflammation, NK cells and implantation: friend and foe (the good, the bad and the ugly?): replacing placental viviparity in an evolutionary perspective

This review summarises an invited talk presented at the 2012 ESRI/ASRI meeting in Hamburg, concerning current views of inflammation in pregnancy, which is timely given that the effects of a local injury in the uterus acts to favour implantation. Recalling that inflammation can be good (it is useful and necessary for implantation), bad (in implantation failure, RSA) and ugly (at the extreme, endometriosis is associated with pain and infertility) leads to consideration of its status in pregnancy. Its role in implantation and the fact that pregnancy maintains some aspects of inflammation throughout, leads to revision of not only concepts of immunosuppression and the Th1/Th2 paradigm, but also the feto-maternal relationship as seen since Medawar's hypotheses were advanced. This is examined from an evolutionary perspective, which should lead to further review of our perception of uterine NK cells, and the emergence of Treg cells to control some aspects of adaptive immunity, which appeared long after placentation.

High fat diet-induced gut microbiota exacerbates inflammation and obesity in mice via the TLR4 signaling pathway

Background & Aims

While it is widely accepted that obesity is associated with low-grade systemic inflammation, the molecular origin of the inflammation remains unknown. Here, we investigated the effect of endotoxin-induced inflammation via TLR4 signaling pathway at both systemic and intestinal levels in response to a high-fat diet.

Methods

C57BL/6J and TLR4-deficient C57BL/10ScNJ mice were maintained on a low-fat (10 kcal % fat) diet (LFD) or a high–fat (60 kcal % fat) diet (HFD) for 8 weeks.

Results

HFD induced macrophage infiltration and inflammation in the adipose tissue, as well as an increase in the circulating proinflammatory cytokines. HFD increased both plasma and fecal endotoxin levels and resulted in dysregulation of the gut microbiota by increasing the Firmicutes to Bacteriodetes ratio. HFD induced the growth of Enterobecteriaceae and the production of endotoxin in vitro. Furthermore, HFD induced colonic inflammation, including the increased expression of proinflammatory cytokines, the induction of Toll-like receptor 4 (TLR4), iNOS, COX-2, and the activation of NF-κB in the colon. HFD reduced the expression of tight junction-associated proteins claudin-1 and occludin in the colon. HFD mice demonstrated higher levels of Akt and FOXO3 phosphorylation in the colon compared to the LFD mice. While the body weight of HFD-fed mice was significantly increased in both TLR4-deficient and wild type mice, the epididymal fat weight and plasma endotoxin level of HFD-fed TLR4-deficient mice were 69% and 18% of HFD-fed wild type mice, respectively. Furthermore, HFD did not increase the proinflammatory cytokine levels in TLR4-deficient mice.

Conclusions

HFD induces inflammation by increasing endotoxin levels in the intestinal lumen as well as in the plasma by altering the gut microbiota composition and increasing its intestinal permeability through the induction of TLR4, thereby accelerating obesity.

Complement in pregnancy: a delicate balance

The complement system is a key component of innate host defence that, under normal conditions, is responsible for the opsonization and destruction of potential pathogens. However, inappropriate or excessive activation of complement can have a detrimental effect on the host and has been implicated in the pathophysiology of numerous disease states. Recently, there has been increasing evidence for a role of the complement system and, in particular, the potent pro-inflammatory anaphylatoxin complement component 5a (C5a) in both normal and complicated pregnancy. The following review describes the results of in vitro, animal, and human clinical studies investigating the role of the complement system in healthy pregnancy, recurrent miscarriage, preterm birth, and preeclampsia.

Stress increases VCAM-1 expression at the fetomaternal interface in an abortion-prone mouse model

Sound stress exposure increases fetal loss via inflammatory pathways. Inflammation is known to up-regulate cell adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), which mediates the adhesion of leukocytes to the vascular endothelium. In this work, we studied the frequency of VCAM-1(+) vessels at the fetomaternal interface in stressed and non-stressed pregnant CBA/J female mice mated with DBA/2J (high fetal loss model) or BALB/c (low fetal loss model) males. The high fetal loss model had fewer large vessels on gestation day 6.5, and stress reduced the frequency of large vessels to a similar number in both high and low fetal loss models. In the high fetal loss model, however, the frequency of VCAM-1+ vessels was dramatically increased. This study shows that VCAM-1 expression is modulated by stress at the fetomaternal interface in abortion-prone cross-breeding.

Neutralization of LPS or blockage of TLR4 signaling prevents stress-triggered fetal loss in murine pregnancy

Maternal stress can cause loss of both histocompatible (syngeneic) and histoincompatible (semiallogeneic) embryos in pregnant mice. Stress increases abortogenic Th1 cytokines and reduces levels of anti-abortogenic Th2 cytokines, progesterone levels, and T regulatory cell activity. While physiological levels of interferon-γ promote vascular remodeling at the feto-maternal interface, an overshooting Th1 cytokine response requires a Toll-like receptor (TLR)-mediated "danger signal" such as lipopolysaccharide (LPS). Interestingly, stress can enhance permeability of mucosal membranes to entry of bacterial products and promote transmucosal migration of commensal bacteria. We hypothesized that bacterial component such as LPS may provide the danger signal through which stress triggers maternal immune activation, subsequently resulting in fetal rejection. Blocking the TLR4 receptor for LPS or neutralization of LPS using bactericidal permeability increasing protein abrogate fetal loss due to sonic stress challenge in DBA/2J-mated CBA/J mice. These treatments prevented stress-triggered immune responses in the decidua, upregulated Treg cells, and reduced the frequency of mature dendritic cells in uterine-draining lymph nodes but not in the uterus. Interestingly, anti-TLR4 treatment only partly ameliorated stress-induced endocrine responses, such as increased hypothalamic corticotropin releasing hormone and vasopressin mRNA expression but not decrease of serum progesterone. Galectin-1 knock-out mice were more susceptible to stress-triggered complete implantation failure rather than fetal loss, which was also abolished by LPS neutralization. Insights provided in this paper shed new light on the mechanisms by which stress affects pregnancy outcome and introduce microbial-derived LPS as a mediator within the cascade of stress-triggered immune and endocrine events during pregnancy.

Tolerance to the foetal allograft?

In this review, we will detail the concept of tolerance and its history in reproductive immunology. We will then consider whether it applies to the foetal-maternal relationship and discuss the mechanisms involved in non-rejection of the foeto-placental unit.

Pravastatin prevents miscarriages in mice: role of tissue factor in placental and fetal injury

Pregnancy loss and intrauterine growth restriction (IUGR) are serious pregnancy complications, and the triggers and mediators of placental and fetal damage are not completely understood. Using a mouse model of recurrent spontaneous miscarriages (DBA/2-mated CBA/J mice) that shares features with human recurrent miscarriage and fetal growth restriction, we identified tissue factor (TF) as an essential participating factor in placental and fetal injury. We have previously shown that C5a releases antiangiogenic molecule sFlt-1 in monocytes that causes defective placental development and fetal death in DBA/2-mated CBA/J mice. In this study, we found that TF not only activates the coagulation pathway, but it also mediates sFlt-1 release in monocytes causing defective placental development and fetal death. Blockade of TF with a monoclonal antibody inhibited sFlt-1 release, prevented the pathological activation of the coagulation pathway, restored placental blood flow, prevented placental oxidative stress, and rescued pregnancies. We also demonstrated that pravastatin, by down-regulating TF expression on monocytes and trophoblasts, prevented placental damage and protected pregnancies in DBA/2-mated CBA/J mice. These studies indicate that TF is an important mediator in fetal death and growth restriction and that statins may be a good treatment for women with recurrent miscarriages and IUGR.