Pregnancy and preeclampsia affect monocyte subsets in humans and rats

Innate immune responses to toll-like receptor stimulation are altered during the course of pregnancy

During pregnancy the maternal immune system has to develop tolerance towards the developing fetus. These changes in maternal immunity can result in increased severity of certain infections, but also in amelioration of autoimmune diseases. Pregnancy-related hormones have been suggested to play a central role in the adaptation of the maternal immune system, but their specific effects on innate immune function is not well understood. In a longitudinal study of pregnant women, we investigated innate immune cell function in response to toll-like receptors (TLR) 4 and 7 stimulation, two TLR pathways playing a critical role in early innate immune recognition of bacteria and viruses. IFNα production by TLR7-stimulated pDCs was decreased in early pregnancy, and increased towards the end of pregnancy. In contrast, pro-inflammatory TLR4-induced TNFα production by monocytes was increased during early pregnancy, but declined after the first trimester. Changes in cytokine production were associated with changes in pregnancy-related hormones and monocyte subpopulations over the course of pregnancy. These data demonstrating a significant association between pregnancy-related hormones and modulation of innate immune responses mediated by TLRs provide novel insights into the immunological adaptations occurring during pregnancy.

Angiotensin II responsiveness after preeclampsia: translational data from an experimental rat model and early-onset human preeclampsia

OBJECTIVE

Formerly preeclamptic women have an increased risk for cardiovascular and renal disease later in life. It is unknown which mechanisms contribute to this increased risk and whether this is induced by preeclampsia or by prepregnancy factors. We hypothesized that the increased risk for cardiovascular disease is partly due to an increased angiotensin II (ang II) responsiveness postpartum and that preeclampsia itself is involved in inducing this increased ang II responsiveness.

METHODS

In never-pregnant, formerly healthy pregnant rats and rats with former experimental preeclampsia [experimental preeclampsia model induced by low-dose endotoxin infusion on day 14 of pregnancy; endotoxin-infused pregnant rats (EP-rats)], ang II responsiveness was studied by measuring changes in blood pressure (BP) and proteinuria after chronic ang II infusion with osmotic minipumps (200 ng/kg per min). In addition, we measured BP and responses to ang II (0.3, 1.0 and 3.0 ng/kg per min) in 18 formerly early-onset preeclamptic, without comorbidities, and 18 formerly healthy pregnant women (controls).

RESULTS

In rats, a significantly higher systolic BP at termination was observed in formerly EP-rats vs. never-pregnant rats after ang II infusion (159.5 ± 29.5 vs. 136.7 ± 16.8; P = 0.049). In response to ang II, there was a significant increase in proteinuria in formerly EP-rats vs. healthy pregnant and never-pregnant rats (P < 0.01 for both). In humans, 1.0 ng/kg per min ang II showed a trend towards an increased mean arterial BP response in formerly preeclamptic women vs. controls (P = 0.057).

CONCLUSION

Our data show an increased ang II responsiveness following (experimental) preeclampsia and support a role for preeclampsia itself in altered ang II responsiveness postpartum.

VEGF may contribute to macrophage recruitment and M2 polarization in the decidua

It is increasingly evident that cytokines and growth factors produced in the decidua play a pivotal role in the regulation of the local immune microenvironment and the establishment of pregnancy. One of the major growth factors produced in the decidua is vascular endothelial growth factor (VEGF), which acts not only on endothelial cells, but also on multiple other cell types, including macrophages. We sought to determine whether decidua-derived VEGF affects macrophage recruitment and polarization using human endometrial/decidual tissue samples, primary human endometrial stromal cells (ESCs), and the human monocyte cell line THP1. In situ hybridization was used for assessment of local VEGF expression and immunohistochemistry was used for identification and localization of CD68-positive endometrial macrophages. Macrophage migration in culture was assessed using a transwell migration assay, and the various M1/M2 phenotypic markers and VEGF expression were assessed using quantitative real-time PCR (qRT-PCR). We found dramatic increases in both VEGF levels and macrophage numbers in the decidua during early pregnancy compared to the secretory phase endometrium (non-pregnant), with a significant increase in M2 macrophage markers, suggesting that M2 is the predominant macrophage phenotype in the decidua. However, decidual samples from preeclamptic pregnancies showed a significant shift in macrophage phenotype markers, with upregulation of M1 and downregulation of M2 markers. In THP1 cultures, VEGF treatment significantly enhanced macrophage migration and induced M1 macrophages to shift to an M2 phenotype. Moreover, treatment with conditioned media from decidualized ESCs induced changes in macrophage migration and polarization similar to that of VEGF treatment. These effects were abrogated by the addition of a potent VEGF inhibitor. Together these results suggest that decidual VEGF plays a significant role in macrophage recruitment and M2 polarization, and that inhibition of VEGF signaling may contribute to the shift in macrophage polarity observed in different pregnancy disorders, including preeclampsia.

Heterogeneity of Bovine Peripheral Blood Monocytes

Peripheral blood monocytes of several species can be divided into different subpopulations with distinct phenotypic and functional properties. Herein, we aim at reviewing published work regarding the heterogeneity of the recently characterized bovine monocyte subsets. As the heterogeneity of human blood monocytes was widely studied and reviewed, this work focuses on comparing bovine monocyte subsets with their human counterparts regarding their phenotype, adhesion and migration properties, inflammatory and antimicrobial functions, and their ability to interact with neutrophilic granulocytes. In addition, the differentiation of monocyte subsets into functionally polarized macrophages is discussed. Regarding phenotype and distribution in blood, bovine monocyte subsets share similarities with their human counterparts. However, many functional differences exist between monocyte subsets from the two species. In contrast to their pro-inflammatory functions in human, bovine non-classical monocytes show the lowest phagocytosis and reactive oxygen species generation capacity, an absent ability to produce the pro-inflammatory cytokine IL-1β after inflammasome activation, and do not have a role in the early recruitment of neutrophils into inflamed tissues. Classical and intermediate monocytes of both species also differ in their response toward major monocyte-attracting chemokines (CCL2 and CCL5) and neutrophil degranulation products (DGP) in vitro. Such differences between homologous monocyte subsets also extend to the development of monocyte-derived macrophages under the influence of chemokines like CCL5 and neutrophil DGP. Whereas the latter induce the differentiation of M1-polarized macrophages in human, bovine monocyte-derived macrophages develop a mixed M1/M2 macrophage phenotype. Although only a few bovine clinical trials analyzed the correlation between changes in monocyte composition and disease, they suggest that functional differences between human and bovine monocyte subsets are also reflected in their different clinical relevance for distinct diseases. In opposite to the human system, where higher blood cell number of non-classical monocytes was widely correlated with several human infectious and non-infectious diseases, higher counts of bovine intermediate monocytes are suggested as a potential biomarker for inflammatory responses postpartum.

Monocyte profile in peripheral blood of gestational diabetes mellitus patients

OBJECTIVE

Gestational diabetes Mellitus has been considered an inflammatory disease involving different cells and mediators in its development. The role of innate immune cells in GDM physiopathology remains unclear, therefore this study was conducted to assess monocyte profile in GDM patients.

DESIGN

This was a case-control study including 20 glucose-tolerant pregnant women (controls) and 18 GDM patients.

METHODS

Flow cytometry was used to assess peripheral blood monocytes subsets (classical, intermediate, non-classical), the expression of TLR4 and CCR2 chemokine receptor (CD192) and cytokines (TNFA, IL6, IL10) secretion by monocytes subsets. In addition, sCD14 serum levels were evaluated by ELISA.

RESULTS

We observed increased percentage of CD14⁺ cells, decreased frequency of intermediate monocytes (CD14⁺CD16⁺), and lower percentage of circulating monocytes (classical, intermediate and non-classical) that express TLR4 in the diabetic group compared to controls. Soluble CD14⁺ serum levels were higher in GDM patients compared to controls. There were no differences in the expression of the CCR2 chemokine receptor and cytokines (TNFA, IL6 and IL10) secretion between the studied groups.

CONCLUSIONS

Our results demonstrated that GDM patients present impaired monocyte profile in the peripheral blood, suggesting that these cells are involved in GDM physiopathology.

Advanced glycation end products and lipopolysaccharides stimulate interleukin-6 secretion via the RAGE/TLR4-NF-κB-ROS pathways and resveratrol attenuates these inflammatory responses in mouse macrophages

Macrophages are essential for regulating the physiology of pregnancy; however, excessive inflammatory responses to macrophages, induced by infection and/or endogenous danger signals, may potentially result in complications during pregnancy. Advanced glycation end-products (AGE) and lipopolysaccharides (LPS) are known to induce inflammation and are associated with adverse developmental outcomes. The aim of the present study was to examine the effect of AGE and LPS on cytokines in the J774 murine macrophage cell line and the potential effect of resveratrol on AGE- and LPS-induced inflammation in macrophages. AGE and LPS significantly increased IL-6 mRNA expression and secretion in J774 macrophages (P<0.05). Although AGE and LPS significantly stimulated IL-1β mRNA expression (P<0.05), they had no significant effect on IL-1β secretion. To assess the receptors for AGE and LPS, including receptor for AGE (RAGE) and Toll-like receptor (TLR4), blocking reagents (RAGE antagonist or TLR4 inhibitor) were added to the J774 macrophages. IL-6 secretion induced by AGE or LPS was significantly inhibited by pretreatment with RAGE antagonist (P<0.05) or TLR4 inhibitor (P<0.05). IL-6 secretion was dependent on nuclear factor (NF)-κB activation and the production of reactive oxygen species (ROS; P<0.05). Resveratrol suppressed mRNA expression and intracellular IL-6 production, resulting in significantly decreased IL-6 secretion after treatment with LPS or AGE (P<0.01). Furthermore, treatment with Ex527, which is a sirtuin-1 (SIRT1) inhibitor, significantly attenuated the anti-inflammatory effect of resveratrol (P<0.05), and treatment with 5-aminoimidazole-4-carboxamide ribonucleotide, which is a 5' adenosine monophosphate-activated protein kinase (AMPK) activator, resulted in a significant decrease in IL-6 secretion in J774 macrophages (P<0.05). The results of the present study indicated that AGE and LPS increase IL-6 secretion depending on NF-κB activation and ROS production through RAGE and/or TLR4 in the J774 murine macrophage cell line. Based on the present study, resveratrol appears to be an effective regulator of the inflammatory responses associated with SIRT1 and AMPK activation in macrophages. These results suggest that resveratrol may have therapeutic applications for controlling immune responses during pregnancy.

Asian Zika virus strains target CD14+ blood monocytes and induce M2-skewed immunosuppression during pregnancy

Blood CD14⁺ monocytes are frontline immunomodulators categorized into classical, intermediate or non-classical subsets, and subsequently differentiated into M1 pro- or M2 anti-inflammatory macrophages on stimulation. Although the Zika virus (ZIKV) rapidly establishes viraemia, the target cells and immune responses, particularly during pregnancy, remain elusive. Furthermore, it is unknown whether African- and Asian-lineage ZIKV have different phenotypic impacts on host immune responses. Using human blood infection, we identified CD14⁺ monocytes as the primary target for African- or Asian-lineage ZIKV infection. When immunoprofiles of human blood infected with ZIKV were compared, a classical/intermediate monocyte-mediated M1-skewed inflammation by the African-lineage ZIKV infection was observed, in contrast to a non-classical monocyte-mediated M2-skewed immunosuppression by the Asian-lineage ZIKV infection. Importantly, infection of the blood of pregnant women revealed an enhanced susceptibility to ZIKV infection. Specifically, Asian-lineage ZIKV infection of pregnant women's blood led to an exacerbated M2-skewed immunosuppression of non-classical monocytes in conjunction with a global suppression of type I interferon-signalling pathway and an aberrant expression of host genes associated with pregnancy complications. Also, 30 ZIKV⁺ sera from symptomatic pregnant patients showed elevated levels of M2-skewed immunosuppressive cytokines and pregnancy-complication-associated fibronectin-1. This study demonstrates the differential immunomodulatory responses of blood monocytes, particularly during pregnancy, on infection with different lineages of ZIKV.

Immune-modulatory effects of syncytiotrophoblast extracellular vesicles in pregnancy and preeclampsia

Unique immunologic adaptations exist to successfully establish and maintain pregnancy and to avoid an immune attack against the semi allogenic fetus. These adaptations occur both locally at the maternofetal interface and in the peripheral circulation and affect the innate as well as the adaptive immune system. Pregnancy is characterized by a general inflammatory state with activation of monocytes and granulocytes, but also with suppressive lymphocytes (regulatory T cells), and skewing towards T helper 2 immunity. The pregnancy complication preeclampsia is associated with an exaggerated inflammatory state and predominance of T helper 1 and 17 immunity. The syncytiotrophoblast has been found to secrete extracellular vesicles as communication factors into the maternal circulation. Syncytiotrophoblast extracellular vesicles from normal pregnancy have been shown to interact with monocytes, granulocytes, T cells and natural killer cells and influence the function of these cells. In doing so, they may support the inflammatory state of normal pregnancy as well as the suppressive lymphocyte phenotype. During preeclampsia, syncytiotrophoblast extracellular vesicles are not only increased in numbers but also showed an altered molecular load. Based on data from in vitro studies, it can be suggested that syncytiotrophoblast extracellular vesicles from preeclamptic pregnancies may support the exaggerated inflammatory state during preeclampsia. In this review, we discuss the immunological functions of syncytiotrophoblast extracellular vesicles and their involvement in adapting the maternal peripheral immunological adaptations to pregnancy.

Bone Marrow-Derived Mesenchymal Stem Cells-Mediated Protection Against Organ Dysfunction in Disseminated Intravascular Coagulation Is Associated With Peripheral Immune Responses

Disseminated intravascular coagulation (DIC) is a fatal thrombohemorrhagic disorder. Bone marrow-derived mesenchymal stem cells (BMSCs) are multipotent stem cells that have tremendous therapeutic effect. Our aim was to explore whether the immune mechanisms were associated with BMSCs-afforded protection against DIC. We generated a rat model of DIC by lipopolysaccharide (LPS, 3 mg/kg) injection via the tail vein. In the treatment group, rats were pre-treated with 1 × l0³ , 1 × l0⁴ , 1 × l0⁵ , and 1 × l0⁶ allogeneic BMSCs before LPS injection. Blood sample was withdrawn from the abdominal aorta at 0 (before), 4, and 8 h after LPS injection and used for biochemical analyses. After experiments, the mice were sacrificed and their organs were harvested and observed by H&E and PTAH staining. Continuous infusion of LPS into the rats gradually impaired the hemostatic parameters and damaged organ functions. However, pre-treatment with BMSCs dose-dependently improved the hemostatic parameters. Meanwhile, the treatment significantly suppressed the fibrin microthrombi formation and alleviated liver, heart, lung, and renal injuries. Flow cytometry analysis demonstrated that BMSCs pre-treatment inhibited LPS-induced upregulation of CD3⁺ CD8⁺ T cells and CD3⁺ /CD161a⁺ NKT cells in the peripheral blood. BMSCs pre-treatment reversed the upregualtion of the B-cell population and the percentage of CD43⁺ /CD172a⁺ monocytes in the DIC models. Finally, BMSCs pre-treatment decreased the levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1β (IL-1β), and interleukin-6 (IL-6) and increased the levels of interleukin-10 (IL-10) in LPS-induced DIC models. Pre-treatment with BMSCs can reduce coagulation and alleviate organ dysfunction via peripheral immune responses in LPS-induced DIC rat model. J. Cell. Biochem. 118: 3184-3192, 2017. © 2017 Wiley Periodicals, Inc.

Extracellular ATP and adenosine: The Yin and Yang in immune responses?

Extracellular adenosine 5'-triphosphate (ATP) and adenosine molecules are intimately involved in immune responses. ATP is mostly a pro-inflammatory molecule and is released during hypoxic condition and by necrotic cells, as well as by activated immune cells and endothelial cells. However, under certain conditions, for instance at low concentrations or at prolonged exposure, ATP may also have anti-inflammatory properties. Extracellular ATP can activate both P2X and P2Y purinergic receptors. Extracellular ATP can be hydrolyzed into adenosine in a two-step enzymatic process involving the ectonucleotidases CD39 (ecto-apyrase) and CD73. These enzymes are expressed by many cell types, including endothelial cells and immune cells. The counterpart of ATP is adenosine, which is produced by breakdown of intra- or extracellular ATP. Adenosine has mainly anti-inflammatory effects by binding to the adenosine, or P1, receptors (A1, A2A, A2B, and A3). These receptors are also expressed in many cells, including immune cells. The final effect of ATP and adenosine in immune responses depends on the fine regulatory balance between the 2 molecules. In the present review, we will discuss the current knowledge on the role of these 2 molecules in the immune responses.

Myometrial cytokines and their role in the onset of labour

Human labour is an inflammatory event, physiologically driven by an interaction between hormonal and mechanical factors and pathologically associated with infection, bleeding and excessive uterine stretch. The initiation and communicators of inflammation is still not completely understood; however, a key role for cytokines has been implicated. We summarise the current understanding of the nature and role of cytokines, chemokines and hormones and their involvement in signalling within the myometrium particularly during labour.

Maternal monocytes in pregnancy and preeclampsia in humans and in rats

Monocytes are short-lived cells, arising from the bone marrow and maturing in the circulation. They play an important role in immune responses and are thought to be important for healthy pregnancy. In humans, 3 subpopulations of monocytes have been identified: classical, intermediate and non-classical monocytes. These subpopulations have different functions and phenotypical characteristics. Healthy pregnancy is characterized by a pro-inflammatory condition, with increased numbers of monocytes and monocyte activation as well as with increased numbers of intermediate monocytes and decreased numbers of classical monocytes. This may suggest monocyte maturation. Preeclampsia is an important pregnancy complication characterized by hypertension and proteinuria developing in the second half of pregnancy. The pathophysiology of preeclampsia is associated with further activation of the inflammatory response, further activation of monocytes and further monocyte maturation. In the present review we focus on the role of monocyte activation and maturation in healthy and preeclamptic pregnancy.

Impact of Systemic Inflammation on the Progression of Gestational Diabetes Mellitus

With increasing rates of obesity and new diagnostic criteria for gestational diabetes mellitus (GDM), the overall prevalence of GDM is increasing worldwide. Women with GDM have an increased risk of maternal and fetal complications during pregnancy as well as long-term risks including higher prevalence of type 2 diabetes mellitus and cardiovascular disease. In recent years, the role of immune activation and inflammation in the pathogenesis of GDM has gained increasing attention. This monograph explores the current state of the literature as regards the expression of markers of inflammation in the maternal circulation, placenta, and adipose tissue of women with GDM.

The role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding

BACKGROUND

Human pregnancy requires robust hemostasis to prevent hemorrhage during extravillous trophoblast (EVT) invasion of the decidualized endometrium, modification of spiral arteries and post-partum processes. However, decidual hemorrhage (abruption) can occur throughout pregnancy from poorly transformed spiral arteries, causing fetal death or spontaneous preterm birth (PTB), or it can promote the aberrant placentation observed in intrauterine growth restriction (IUGR) and pre-eclampsia; all leading causes of perinatal or maternal morbidity and mortality. In non-fertile cycles, the decidua undergoes controlled menstrual bleeding. Abnormal uterine bleeding (AUB) accompanying progestin-only, long-acting, reversible contraception (pLARC) accounts for most discontinuations of these safe and highly effective agents, thereby contributing to unwanted pregnancies and abortion. The aim of this study was to investigate the role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding.

METHODS

We conducted a critical review of the literature arising from PubMed searches up to December 2015, regarding in situ and in vitro expression and regulation of several specific proteins involved in uterine hemostasis in decidua and cycling endometrium. In addition, we discussed clinical and molecular mechanisms associated with pLARC-induced AUB and pregnancy complications with abruptions, chorioamnionitis or pre-eclampsia.

RESULTS

Progestin-induced decidualization of estradiol-primed human endometrial stromal cells (HESCs) increases in vivo and in vitro expression of tissue factor (TF) and type-1 plasminogen activator inhibitor (PAI-1) while inhibiting plasminogen activators (PAs), matrix metalloproteinases (MMPs), and the vasoconstrictor, endothelin-1 (ET-1). These changes in decidual cell-derived regulators of hemostasis, fibrinolysis, extracellular matrix (ECM) turnover, and vascular tone prevent hemorrhage during EVT invasion and vascular remodeling. In non-fertile cycles, progesterone withdrawal reduces TF and PAI-1 while increasing PA, MMPs and ET-1, causing menstrual-associated bleeding, fibrinolysis, ECM degradation and ischemia. First trimester decidual hemorrhage elicits later adverse outcomes including pregnancy loss, pre-eclampsia, abruption, IUGR and PTB. Decidual hemorrhage generates excess thrombin that binds to decidual cell-expressed protease-activated receptors (PARs) to induce chemokines promoting shallow placentation; such bleeding later in pregnancy generates thrombin to down-regulate decidual cell progesterone receptors and up-regulate cytokines and MMPs linked to PTB. Endometria of pLARC users display ischemia-induced excess vasculogenesis and progestin inhibition of spiral artery vascular smooth muscle cell proliferation and migration leading to dilated fragile vessels prone to bleeding. Moreover, aberrant TF-derived thrombin signaling also contributes to the pathogenesis of endometriosis via induction of angiogenesis, inflammation and cell survival.

CONCLUSION

Perivascular decidualized HESCs promote endometrial hemostasis during placentation yet facilitate menstruation through progestational regulation of hemostatic, proteolytic, and vasoactive proteins. Pathological endometrial hemorrhage elicits excess local thrombin generation, which contributes to pLARC associated AUB, endometriosis and adverse pregnancy outcomes through several biochemical mechanisms.

A Single 9-Colour Flow Cytometric Method to Characterise Major Leukocyte Populations in the Rat: Validation in a Model of LPS-Induced Pulmonary Inflammation

The rat is a commonly used model for immunological investigation. Yet basic research and characterisation of leukocyte populations and sub-sets lags far behind murine research, with inconsistency on reported leukocyte markers and their overlap. These shortcomings limit the opportunity for more complex and advanced rat immunology research. In this study, we developed a robust 9-colour flow-cytometric protocol to elucidate the major blood and tissue rat leukocyte populations, and validated it in a model of LPS-induced pulmonary inflammation. Blood and tissues (lung, BALF, spleen, liver, bone marrow) from naïve Sprague-Dawley rats were collected and analysed by flow cytometry (FCM). Rats were exposed to aerosolised saline or LPS (1 mg/mL), at 3 and 24 hrs thereafter blood, lung and BALF were collected and analysed using FCM and ELISA. Neutrophils, two monocyte subsets, NK Cells, B Cells, CD4+, CD8+ T Cells and alveolar macrophages can be identified simultaneously across different tissues using a 9-colour panel. Neutrophils and monocytes can be distinguished based upon differential expression of CD43 and His48. Neutrophils and CD43Lo/His48Hi monocyte-macrophages are elevated in the lung at 3 and 24 hrs during LPS-induced pulmonary inflammation. This validated method for leukocyte enumeration will offer a platform for greater consistency in future rat immunology and inflammation research.

Immune Mechanisms Linking Obesity and Preeclampsia

Preeclampsia (PE) is characterized by hypertension occurring after the twentieth week of pregnancy. It is a significant contributor to maternal and perinatal morbidity and mortality in developing countries and its pervasiveness is increasing within developed countries including the USA. However, the mechanisms mediating the pathogenesis of this maternal disorder and its rising prevalence are far from clear. A major theory with strong experimental evidence is that placental ischemia, resulting from inappropriate remodeling and widening of the maternal spiral arteries, stimulates the release of soluble factors from the ischemic placenta causing maternal endothelial dysfunction and hypertension. Aberrant maternal immune responses and inflammation have been implicated in each of these stages in the cascade leading to PE. Regarding the increased prevalence of this disease, it is becoming increasingly evident from epidemiological data that obesity, which is a state of chronic inflammation in itself, increases the risk for PE. Although the specific mechanisms whereby obesity increases the rate of PE are unclear, there are strong candidates including activated macrophages and natural killer cells within the uterus and placenta and activation in the periphery of T helper cells producing cytokines including TNF-α, IL-6 and IL-17 and the anti-angiogenic factor sFlt-1 and B cells producing the agonistic autoantibodies to the angiotensin type 1 receptor (AT1-aa). This review will focus on the immune mechanisms that have been implicated in the pathogenesis of hypertension in PE with an emphasis on the potential importance of inflammatory factors in the increased risk of developing PE in obese pregnancies.

Competitive SWIFT cluster templates enhance detection of aging changes

Clustering‐based algorithms for automated analysis of flow cytometry datasets have achieved more efficient and objective analysis than manual processing. Clustering organizes flow cytometry data into subpopulations with substantially homogenous characteristics but does not directly address the important problem of identifying the salient differences in subpopulations between subjects and groups. Here, we address this problem by augmenting SWIFT—a mixture model based clustering algorithm reported previously. First, we show that SWIFT clustering using a “template” mixture model, in which all subpopulations are represented, identifies small differences in cell numbers per subpopulation between samples. Second, we demonstrate that resolution of inter‐sample differences is increased by “competition” wherein a joint model is formed by combining the mixture model templates obtained from different groups. In the joint model, clusters from individual groups compete for the assignment of cells, sharpening differences between samples, particularly differences representing subpopulation shifts that are masked under clustering with a single template model. The benefit of competition was demonstrated first with a semisynthetic dataset obtained by deliberately shifting a known subpopulation within an actual flow cytometry sample. Single templates correctly identified changes in the number of cells in the subpopulation, but only the competition method detected small changes in median fluorescence. In further validation studies, competition identified a larger number of significantly altered subpopulations between young and elderly subjects. This enrichment was specific, because competition between templates from consensus male and female samples did not improve the detection of age‐related differences. Several changes between the young and elderly identified by SWIFT template competition were consistent with known alterations in the elderly, and additional altered subpopulations were also identified. Alternative algorithms detected far fewer significantly altered clusters. Thus SWIFT template competition is a powerful approach to sharpen comparisons between selected groups in flow cytometry datasets. © 2015 The Authors. Published Wiley Periodicals Inc.

Immunological Adaptations to Pregnancy in Women with Type 1 Diabetes

Despite adequate glycemic control, pregnancy outcome of women with type 1 diabetes (T1D) is still unfavorable as compared to healthy women. In a rat-model of T1D under normoglycemic conditions, adverse pregnancy outcome was also observed, which was associated with aberrant immunological adaptations to pregnancy. Because similar processes may occur in women with T1D we studied the systemic immune response in non-pregnant and pregnant women with and without T1D. The systemic immune response was assessed by using flow cytometry to evaluate the number and activational status of subpopulations of lymphocytes, Natural Killer cells and monocytes in peripheral blood of non-pregnant and pregnant women with and without T1D. An increased white blood cell count, an increased Th1/Th2 ratio, increased Natural Killer cell expression of CD335 and enhanced activation of intermediate and non-classical monocytes was observed in pregnant women with T1D vs. healthy pregnant women. Also, the pregnancy outcome (i.e. incidence of preterm delivery and macrosomia) of women with T1D was unfavorable as compared to healthy women. This study showed that in T1D, the immunological adaptations to pregnancy are disturbed. In addition to hyperglycemia, these different immunological adaptations may be responsible for the greater frequency of complications in pregnant women with T1D.

Remote Ischemic Preconditioning-Mediated Neuroprotection against Stroke is Associated with Significant Alterations in Peripheral Immune Responses

AIMS

Remote ischemic preconditioning (RIPC) of a limb is a clinically feasible strategy to protect against ischemia-reperfusion injury after stroke. However, the mechanism underlying RIPC remains elusive.

METHODS

We generated a rat model of noninvasive RIPC by four repeated cycles of brief blood flow constriction (5 min) in the hindlimbs using a tourniquet. Blood was collected 1 h after preconditioning and 3 days after brain reperfusion. The impact of RIPC on immune cell and cytokine profiles prior to and after transient middle cerebral artery occlusion (MCAO) was assessed.

RESULTS

Remote ischemic preconditioning protects against focal ischemia and preserves neurological functions 3 days after stroke. Flow cytometry analysis demonstrated that RIPC ameliorates the post-MCAO reduction of CD3(+)CD8(+) T cells and abolishes the reduction of CD3(+)/CD161a(+) NKT cells in the blood. In addition, RIPC robustly elevates the percentage of B cells in peripheral blood, thereby reversing the reduction in the B-cell population after stroke. RIPC also markedly elevates the percentage of CD43(+)/CD172a(+) noninflammatory resident monocytes, without any impact on the percentage of CD43(-)/CD172a(+) inflammatory monocytes. Finally, RIPC induces IL-6 expression and enhances the elevation of TNF-α after stroke.

CONCLUSION

Our results reveal dramatic immune changes during RIPC-afforded neuroprotection against cerebral ischemia.

Gender differences in response to acute and chronic angiotensin II infusion: a translational approach

Women with renal disease progress at a slower rate to end stage renal disease than men. As angiotensin II has both hemodynamic and direct renal effects, we hypothesized that the female protection may result from gender differences in responses to angiotensin II. Therefore, we studied gender differences in response to angiotensin II, during acute (human) and chronic (rats) angiotensin II administration. In young healthy men (n = 18) and women (n = 18) we studied the responses of renal hemodynamics (¹²⁵I-iothalamate and ¹³¹I-Hippuran) and blood pressure to graded angiotensin II infusion (0.3, 1.0, and 3.0 ng/kg/min for 1 h). Men had increased responses of diastolic blood pressure (P = 0.01), mean arterial pressure (P = 0.05), and a more pronounced decrease in effective renal plasma flow (P = 0.009) than women. We measured the changes in proteinuria and blood pressure in response to chronic administration (200 ng/kg/min for 3 weeks) of angiotensin II in rats. Male rats had an increased response of proteinuria compared with females (GEE analysis, P = 0.001). Male, but not female, angiotensin II-treated rats had increased numbers of renal interstitial macrophages compared to sham-treated rats (P < 0.001). In conclusion, gender differences are present in the response to acute and chronic infusion of angiotensin II. Difference in angiotensin II sensitivity could play a role in gender differences in progression of renal disease.

CD14++ CD16+ HLA-DR+ Monocytes in Peripheral Blood are Quantitatively Correlated with the Severity of Pre-eclampsia

PROBLEM

We aim to investigate the proportion and absolute counts of peripheral blood monocyte subsets in women with normal pregnancy (NP) and pre-eclampsia (PE), and their correlation with the clinical manifestation and severity of PE.

METHOD OF STUDY

Peripheral blood was obtained from women with NP (n = 30), mild PE (MPE, n = 15) and severe PE (SPE, n = 30). The proportion and absolute counts of CD16(+) monocytes and the subsets including intermediate (CD14(++) CD16(+) HLA-DR(+) ) and non-classical (CD14(+) CD16(++) HLA-DR(+) ) monocytes were determined by flow cytometric analysis.

RESULTS

Women with MPE and SPE had significantly increased absolute count of CD14(++) CD16(+) HLA-DR(+) monocyte subsets (P < 0.01 each) as compared to NP women. In addition, there were significant differences in the absolute count of CD14(++) CD16(+) HLA-DR(+) monocyte subsets between MPE and SPE groups (P < 0.05). The proportion of CD14(++) CD16(+) HLA-DR(+) monocyte subsets was significantly increased in SPE compared to MPE and NP (P < 0.01 each). The absolute count (r = 0.332, P < 0.05) and proportion (r = 0.447, P < 0.01) of CD14(++) CD16(+) HLA-DR(+) monocytes were positively correlated with the severity of PE. Multivariate logistic regression analysis further revealed that the absolute count of CD14(++) CD16(+) HLA-DR(+) monocytes was a potential marker for PE (P < 0.01).

CONCLUSION

A preferential increase in peripheral blood CD14(++) CD16(+) HLA-DR(+) monocytes is quantitatively correlated with clinical manifestation of PE.

Trophoblast induces monocyte differentiation into CD14+/CD16+ macrophages

PROBLEM

During early pregnancy, macrophages and trophoblast come into close contact during placenta development, and regulated cross talk between these cellular compartments is crucial for maintaining a healthy pregnancy. As trophoblast cells constitutively secrete many chemokines and cytokines, we hypothesize that trophoblast-secreted factors can differentiate monocytes into a decidual phenotype. In this study, we describe a unique macrophage phenotype, following monocytes' exposure to trophoblast-soluble factors.

METHOD OF STUDY

Peripheral blood monocytes were treated with or without conditioned media (CM) from first trimester trophoblast cells. Phenotypic changes and phagocytic capacity were determined by flow cytometry. Cytokine and chemokine production was determined by multiplex analysis.

RESULTS

Monocytes exposed to trophoblast factors undergo morphologic changes characterized by a gain in size and complexity and acquire a unique phenotype characterized by gain of CD14 surface expression as well as CD16. The presence of CD14+/CD16+ macrophages was confirmed in normal decidua. These cells secrete higher levels of IL-1b, IL-10, and IP-10 and have increased capacity for phagocytosis.

CONCLUSION

We demonstrate that trophoblast-secreted factors can induce monocyte differentiation into a unique macrophage phenotype. These findings suggest that the microenvironment of the placenta can modulate the phenotype of macrophages present at the decidua.

Reprint of: Monocyte subsets in man and other species

Monocytes are white blood cells that belong to the mononuclear phagocyte system. They derive from precursors in bone marrow, from there they go into blood, where they have a half-life of 1-2 days, and then they migrate into the various tissues. Monocyte subsets were discovered by means of flow cytometry in human blood some 20 years ago and their phenotype and function has been characterized in detail in health and disease. The subset classification as classical, intermediate and non-classical monocytes appears to apply to other species as well, as reviewed in here by comparing data on human monocytes with the respective cells in the mouse, the rat, the pig, the cow and the horse. The data show that the subsets are homologous between the species but there are important differences in subset-specific gene expression such that findings in a given species cannot be directly translated to man.

Monocytes and macrophages in pregnancy and pre-eclampsia

Preeclampsia is an important complication in pregnancy, characterized by hypertension and proteinuria in the second half of pregnancy. Generalized activation of the inflammatory response is thought to play a role in the pathogenesis of pre-eclampsia. Monocytes may play a central role in this inflammatory response. Monocytes are short lived cells that mature in the circulation and invade into tissues upon an inflammatory stimulus and develop into macrophages. Macrophages are abundantly present in the endometrium and play a role in implantation and placentation in normal pregnancy. In pre-eclampsia, these macrophages appear to be present in larger numbers and are also activated. In the present review, we focused on the role of monocytes and macrophages in the pathophysiology of pre-eclampsia.

Extracellular adenosine triphosphate affects systemic and kidney immune cell populations in pregnant rats

PROBLEM

Changes in the systemic immune response are found in preeclampsia. This may be related to high extracellular adenosine triphosphate (ATP) levels. The question arose whether ATP could affect immune responses in pregnancy. Previously, we investigated whether ATP affected monocyte activation and subpopulations. Here, we investigated ATP-induced changes in other immune cell populations in pregnant rats, systemically and in the kidney, an affected organ in preeclampsia.

METHOD OF STUDY

Using flow cytometry or immunohistochemistry, blood and kidney leukocytes were studied in pregnant and non-pregnant rats at different intervals after ATP or saline infusion.

RESULTS

Adenosine triphosphate (ATP) infusion induced increased peripheral blood non-classical monocytes and decreased T lymphocyte subsets in pregnant rats only, higher glomerular macrophage and T lymphocyte numbers in non-pregnant animals 1 day after infusion, and higher glomerular macrophage numbers in pregnant rats 6 days after infusion.

CONCLUSION

Adenosine triphosphate (ATP) infusion in pregnant rats induced a pregnancy-specific inflammatory response. Increased ATP levels could potentially contribute to development of the inflammatory response of preeclampsia.

Monocyte subsets in man and other species

Monocytes are white blood cells that belong to the mononuclear phagocyte system. They derive from precursors in bone marrow, from there they go into blood, where they have a half-life of 1-2 days, and then they migrate into the various tissues. Monocyte subsets were discovered by means of flow cytometry in human blood some 20 years ago and their phenotype and function has been characterized in detail in health and disease. The subset classification as classical, intermediate and non-classical monocytes appears to apply to other species as well, as reviewed in here by comparing data on human monocytes with the respective cells in the mouse, the rat, the pig, the cow and the horse. The data show that the subsets are homologous between the species but there are important differences in subset-specific gene expression such that findings in a given species cannot be directly translated to man.

Decreased seizure threshold in an eclampsia-like model induced in pregnant rats with lipopolysaccharide and pentylenetetrazol treatments

Objective

Eclampsia is a poorly understood but potentially fatal complication of pregnancy. Research to date on this disorder has been hampered by the lack of a suitable animal model. To correct this deficiency, this report describes the generation of a rat eclampsia-like model using pentylenetetrazol (PTZ) in a previously established rat preeclampsia model.

Method

Rats were administered lipopolysaccharide (1.0 µg/kg) by tail vein injection on gestational day 14 to establish preeclampsia (PE). PE and control rats (non-pregnant, NP; normal-pregnant, P) were injected intraperitoneally (i.p.) with PTZ (40 mg/kg) to induce seizures. In separate experiments, MgSO₄ (270 mg/kg IP) was injected in advance of PTZ into PE rats to observe its effect on PTZ-induced seizures.

Results

PE conditions were verified in rats after LPS administration by significantly higher blood pressure (P<0.01) and urinary albumin excretion (P<0.05), elevated sFlt-1 (P<0.05) and decreased PlGF serum levels (P<0.05), and evidence of hepatic dysfunction compared to control groups. PTZ successfully induced seizure activity in all groups studied. Latency to seizure was significantly (P<0.01) less in the PE-PTZ group (73.2±6.6 sec.) than in PTZ-treated controls (107.0±7.4 sec.). Pretreatment with MgSO₄ prolonged (P<0.05) latency to seizure, shortened seizure duration and decreased seizure rates. Significant increased (P<0.05) in the serum levels of the inflammatory cytokines TNF-α and IL-1β in PE and PE-PTZ groups, and decreased (P<0.05) in their levels following MgSO₄ administration.

Conclusion

This PTZ-induced eclampsia-like rat model is comparable to the human condition of eclampsia and may serve as a useful research tool for future studies of this disease. The increased inflammatory cytokines in preeclampsia are coincident with a decreased threshold for PTZ-induced seizures, suggesting that an inflammatory mechanism may contribute to the susceptibility to seizure activity and inflammation might have an important role in eclampsia.

Systemic increase in human maternal circulating CD14+CD16- MCP-1+ monocytes as a marker of labor

OBJECTIVES

To study the influence of pregnancy and labor on the proportion and level of activation of monocyte subpopulations in human pregnancy.

STUDY DESIGN

Peripheral blood samples were obtained from healthy nonpregnant women (n = 6); women in the third-trimester of healthy pregnancies (n = 18) and women with preterm premature rupture of membranes (n = 46), just before delivery for the last 2 groups. Monocyte subpopulations were characterized by flow cytometry using CD14, CD16, and activation level using macrophage chemoattractant protein-1 (MCP-1) and CCR2 antibodies.

RESULTS

The relative proportion of each monocyte subset in nonpregnant women was similar to that in women with healthy or complicated pregnancies. However, pregnancy was associated with a significant decrease in MCP-1 expressing monocytes (79.5% ± 19.8% vs 9.3% ± 6.8% and 11.9% ± 8.3% for nonpregnant, healthy pregnancy, and preterm premature rupture of membranes (respectively, P < .05). Spontaneous labor was associated with a return to nonpregnant values for the proportion of MCP-1 expressing monocytes in both normal (74.4% ± 16.9) and preterm premature rupture of membranes pregnancy (68.4% ± 35.6), irrespective of the mode of delivery (vaginal or cesarean section). This was not observed in women who delivered without spontaneous labor onset. CCR-2 (MCP-1 receptor) expression was not modified in monocytes at the time of labor, but was significantly increased in granulocytes (3646 ± 1080 vs 7338 ± 2718 for nonlaboring and laboring preterm premature rupture of membranes, respectively, P < .05) CONCLUSION: In light of previous reports of a role for MCP-1 in labor, our results suggest the downregulation of activation levels of monocytes, via MCP-1 expression might be involved in maternofetal immune tolerance. Monocyte reactivation might be associated with labor.

Modulation of mononuclear phagocyte inflammatory response by liposome-encapsulated voltage gated sodium channel inhibitor ameliorates myocardial ischemia/reperfusion injury in rats

BACKGROUND

Emerging evidence shows that anti-inflammatory strategies targeting inflammatory monocyte subset could reduce excessive inflammation and improve cardiovascular outcomes. Functional expression of voltage-gated sodium channels (VGSCs) have been demonstrated in monocytes and macrophages. We hypothesized that mononuclear phagocyte VGSCs are a target for monocyte/macrophage phenotypic switch, and liposome mediated inhibition of mononuclear phagocyte VGSC may attenuate myocardial ischemia/reperfusion (I/R) injury and improve post-infarction left ventricular remodeling.

METHODOLOGY/PRINCIPAL FINDINGS

Thin film dispersion method was used to prepare phenytoin (PHT, a non-selective VGSC inhibitor) entrapped liposomes. Pharmacokinetic study revealed that the distribution and elimination half-life of PHT entrapped liposomes were shorter than those of free PHT, indicating a rapid uptake by mononuclear phagocytes after intravenous injection. In rat peritoneal macrophages, several VGSC α subunits (NaV1.1, NaV1.3, NaV1.4, NaV1.5, NaV1.6, NaV1.7, NaVX, Scn1b, Scn3b and Scn4b) and β subunits were expressed at mRNA level, and PHT could suppress lipopolysaccharide induced M1 polarization (decreased TNF-α and CCL5 expression) and facilitate interleukin-4 induced M2 polarization (increased Arg1 and TGF-β1 expression). In vivo study using rat model of myocardial I/R injury, demonstrated that PHT entrapped liposome could partially suppress I/R injury induced CD43+ inflammatory monocyte expansion, along with decreased infarct size and left ventricular fibrosis. Transthoracic echocardiography and invasive hemodynamic analysis revealed that PHT entrapped liposome treatment could attenuate left ventricular structural and functional remodeling, as shown by increased ejection fraction, reduced end-systolic and end-diastolic volume, as well as an amelioration of left ventricular systolic (+dP/dt max) and diastolic (-dP/dt min) functions.

CONCLUSIONS/SIGNIFICANCE

Our work for the first time demonstrates the therapeutic potential of VGSC antagonism via liposome mediated monocyte/macrophage targeting in acute phase after myocardial I/R injury. These results suggest that VGSCs in mononuclear phagocyte system might be a novel target for immunomodulation and treatment of myocardial I/R injury.

Aberrant Pregnancy Adaptations in the Peripheral Immune Response in Type 1 Diabetes: A Rat Model

Introduction

Despite tight glycemic control, pregnancy complication rate in type 1 diabetes patients is higher than in normal pregnancy. Other etiological factors may be responsible for the development of adverse pregnancy outcome. Acceptance of the semi-allogeneic fetus is accompanied by adaptations in the maternal immune-response. Maladaptations of the immune-response has been shown to contribute to pregnancy complications. We hypothesized that type 1 diabetes, as an autoimmune disease, may be associated with maladaptations of the immune-response to pregnancy, possibly resulting in pregnancy complications.

Methods

We studied pregnancy outcome and pregnancy-induced immunological adaptations in a normoglycemic rat-model of type 1 diabetes, i.e. biobreeding diabetes-prone rats (BBDP; 5 non-pregnant rats, 7 pregnant day 10 rats and 6 pregnant day 18 rats) , versus non-diabetic control rats (i.e. congenic non-diabetic biobreeding diabetes-resistant (BBDR; 6 non-pregnant rats, 6 pregnant day 10 rats and 6 pregnant day 18 rats) and Wistar-rats (6 non-pregnant, 6 pregnant day 10 rats and 5 pregnant day 18 rats)).

Results

We observed reduced litter size, lower fetal weight of viable fetuses and increased numbers of resorptions versus control rats. These complications are accompanied by various differences in the immune-response between BBDP and control rats in both pregnant and non-pregnant animals. The immune-response in non-pregnant BBDP-rats was characterized by decreased percentages of lymphocytes, increased percentages of effector T-cells, regulatory T-cells and natural killer cells, an increased Th1/Th2-ratio and activated monocytes versus Wistar and BBDR-rats. Furthermore, pregnancy-induced adaptations in BBDP-rats coincided with an increased Th1/Th2-ratio, a decreased mean fluorescence intensity CD161a/NKR-P1b ratio and no further activation of monocytes versus non-diabetic control rats.

Conclusion

This study suggests that even in the face of strict normoglycemia, pregnancy complications still occur in type 1 diabetic pregnancies. This adverse pregnancy outcome may be related to the aberrant immunological adaptations to pregnancy in diabetic rats.

The Placenta in Toxicology. Part II

During pregnancy, the maternal immune system is challenged by the semiallogeneic fetus, which must be tolerated without compromising fetal or maternal health. This review updates the systemic and local immune changes taking place during human pregnancy, including some examples in rodents. Systemic changes are induced by contact of maternal blood with placental factors and include enhanced innate immunity with increased activation of granulocytes and nonclassical monocytes. Although a bias toward T helper (Th2) and regulatory T cell (Treg) immunity has been associated with healthy pregnancy, the relationship between different circulating Th cell subsets is not straightforward. Instead, these adaptations appear most evidently at the fetal–maternal interface, where for instance Tregs are enriched and promote fetal tolerance. Also innate immune cells, that is, natural killer cells and macrophages, are enriched, constituting the majority of decidual leukocytes. These cells not only contribute to immune regulation but also aid in establishing the placenta by promoting trophoblast recruitment and angiogenesis. Thus, proper interaction between leukocytes and placental trophoblasts is necessary for normal placentation and immune adaptation. Consequently, spontaneous maladaptation or interference of the immune system with toxic substances may be important contributing factors for the development of pregnancy complications such as preeclampsia, preterm labor, and recurrent miscarriages.