The first trimester gravid serum regulates procalcitonin expression in human macrophages skewing their phenotype in vitro

Contribution of macrophages to fetomaternal immunological tolerance

The semi-allogeneic fetus develops in a uniquely immune tolerant environment within the uterus. For successful pregnancy, both the innate and adaptive immune systems must favor acceptance of the fetal allograft. Macrophages are the second most abundant immune cells after natural killer (NK) cells in the decidua. In coordination with decidual NK cells and dendritic cells, macrophages aid in implantation, vascular remodeling, placental development, immune tolerance to placental cells, and maintenance of tissue homeostasis at the maternal-fetal interface. Decidual macrophages show the classical activated (M1) and alternatively activated (M2) phenotypes under the influence of the local milieu of growth factors and cytokines, and appropriate temporal regulation of the M1/M2 switch is vital for successful pregnancy. Disturbances in the mechanisms that control the M1/M2 balance and associated functions during pregnancy can trigger a spectrum of pregnancy complications ranging from preeclampsia and fetal growth restriction to preterm delivery. This review addresses various mechanisms of tolerance, focusing on the basic biology of macrophages, their plasticity and polarization, and their protective roles at the immune-privileged maternal-fetal interface, including direct and indirect roles in promoting fetomaternal immune tolerance.

Sexual Dimorphism in Innate Immunity: The Role of Sex Hormones and Epigenetics

Sexual dimorphism refers to differences between biological sexes that extend beyond sexual characteristics. In humans, sexual dimorphism in the immune response has been well demonstrated, with females exhibiting lower infection rates than males for a variety of bacterial, viral, and parasitic pathogens. There is also a substantially increased incidence of autoimmune disease in females compared to males. Together, these trends indicate that females have a heightened immune reactogenicity to both self and non-self-molecular patterns. However, the molecular mechanisms driving the sexually dimorphic immune response are not fully understood. The female sex hormones estrogen and progesterone, as well as the male androgens, such as testosterone, elicit direct effects on the function and inflammatory capacity of immune cells. Several studies have identified a sex-specific transcriptome and methylome, independent of the well-described phenomenon of X-chromosome inactivation, suggesting that sexual dimorphism also occurs at the epigenetic level. Moreover, distinct alterations to the transcriptome and epigenetic landscape occur in synchrony with periods of hormonal change, such as puberty, pregnancy, menopause, and exogenous hormone therapy. These changes are also mirrored by changes in immune cell function. This review will outline the evidence for sex hormones and pregnancy-associated hormones as drivers of epigenetic change, and how this may contribute to the sexual dimorphism. Determining the effects of sex hormones on innate immune function is important for understanding sexually dimorphic autoimmune diseases, sex-specific responses to pathogens and vaccines, and how innate immunity is altered during periods of hormonal change (endogenous or exogenous).

Relationships between serum procalcitonin level, severity and different stresses of non-septic critically ill patients

Background: To explore the relationships between serum procalcitonin (PCT) level, severity and different stresses of non-septic critically ill patients.

Materials and Methods: Patients were divided into traumatic stress, stroke-induced stress and non-infectious inflammatory stress groups. According to 28-day prognosis, they were divided into survival and death groups. The factors affecting prognosis were studied by multivariate logistic regression analysis.

Results: PCT level was significantly positively correlated with Acute Physiology and Chronic Health Evaluation II (APACHE II) and sequential organ failure assessment (SOFA) scores (P=0.001). The PCT level and abnormality rate of the traumatic stress group significantly exceeded those of other groups (P---lt---0.05). The APACHE II score, SOFA score and 28-day mortality rate of traumatic stress and stroke-induced stress groups significantly exceeded those of the non-infectious inflammatory stress group (P---lt---0.05). The PCT level, APACHE II score and SOFA score of the death group significantly surpassed those of the survival group (P---lt---0.05). With rising PCT level, APACHE II score, SOFA score and 28-day mortality rate all increased, with significant intergroup differences (P---lt---0.01). Multivariate logistic analysis showed that serum PCT level, APACHE II score and SOFA score were independent risk factors for prognosis. The area under ROC curve for prognosis evaluated by PCT level was 0.797 (95%CI = 0.710~0.878, P=0.000). At a 4.3 μg/L cut-off, the sensitivity and specificity for predicting 28-day mortality were 87.4% and 78.1%, respectively.

Conclusion: The serum PCT level of non-septic critically ill patient was positively correlated with severity, which was more likely elevated by traumatic stress than other stresses.

Human Chorionic Gonadotropin-Mediated Immune Responses That Facilitate Embryo Implantation and Placentation

Human chorionic gonadotropin (hCG) serves as one of the first signals provided by the embryo to the mother. Exactly at the time when the first step of the implantation process is initiated and the blastocyst adheres to the maternal endometrium, the embryonic tissue starts to actively secrete hCG. Shortly thereafter, the hormone can be detected in the maternal circulation where its concentration steadily increases throughout early pregnancy as it is continuously released by the forming placenta. Accumulating evidence underlines the critical function of hCG for embryo implantation and placentation. hCG not only regulates biological aspects of these early pregnancy events but also supports maternal immune cells in their function as helpers in the establishment of an adequate embryo-endometrial relationship. In view of its early presence in the maternal circulation, hCG has the potential to influence both local uterine immune cell populations as well as peripheral ones. The current review aims to summarize recent literature on the participation of innate and adaptive immune cells in embryo implantation and placentation with a specific focus on their regulation by hCG.

Uterine Immunity and Microbiota: A Shifting Paradigm

The female reproductive tract harbors distinct microbial communities, as in the vagina, cervical canal, uterus, and fallopian tubes. The nature of the vaginal microbiota is well-known; in contrast, the upper reproductive tract remains largely unexplored. Alteration in the uterine microbiota, which is dependent on the nutrients and hormones available to the uterus, is likely to play an important role in uterine-related diseases such as hysteromyoma, adenomyosis, and endometriosis. Uterine mucosa is an important tissue barrier whose main function is to offer protection against pathogens and other toxic factors, while maintaining a symbiotic relationship with commensal microbes. These characteristics are shared by all the mucosal tissues; however, the uterine mucosa is unique since it changes cyclically during the menstrual cycle as well as pregnancy. The immune system, besides its role in the defense process, plays crucial roles in reproduction as it ensures local immune tolerance to fetal/paternal antigens, trophoblast invasion, and vascular remodeling. The human endometrium contains a conspicuous number of immune cells, mainly Natural Killers (NK) cells, which are phenotypically distinct from peripheral cytotoxic NK, cells and macrophages. The endometrium also contains few lymphoid aggregates comprising B cell and CD8⁺ T cells. The number and the phenotype of these cells change during the menstrual cycle. It has become evident in recent years that the immune cell phenotype and function can be influenced by microbiota. Immune cells can sense the presence of microbes through their pattern recognition receptors, setting up host-microbe interaction. The microbiota exerts an appropriately controlled defense mechanism by competing for nutrients and mucosal space with pathogens. It has recently been considered that uterus is a non-sterile compartment since it seems to possess its own microbiota. There has been an increasing interest in characterizing the nature of microbial colonization within the uterus and its apparent impact on fertility and pregnancy. This review will examine the potential relationship between the uterine microbiota and the immune cells present in the local environment.

Role of Macrophages in Pregnancy and Related Complications

Macrophages (MФs) are the leukocytes produced from differentiation of monocytes and are located in almost all tissues of human body. They are involved in various processes, such as phagocytosis, innate and adaptive immunity, proinflammatory (M1) and anti-inflammatory (M2) activity, depending on the tissue microenvironment. They play a crucial role in pregnancy, and their dysfunction or alteration of polarity is involved in pregnancy disorders, like preeclampsia, recurrent spontaneous abortion, infertility, intrauterine growth restriction, and preterm labor. About 50-60% of decidual leukocytes are natural killer (NK) cells followed by MФs (the second largest population). MФs are actively involved in trophoblast invasion, tissue and vascular remodeling during early pregnancy, besides their role as major antigen-presenting cells in the decidua. These cells have different phenotypes and polarities in different stages of pregnancy. They have also been observed to enhance tumor growth by their anti-inflammatory activity (M2 type) and prevent immunogenic rejection. Targeted alteration of polarity (M1-M2 or vice versa) could be a major focus in the future treatment of pregnancy complications. This review is focused on the role of MФs in pregnancy, their involvement in pregnancy disorders, and decidual MФs as possible therapeutic targets for the treatment of pregnancy complications.

Effect of pregnancy hormone mixtures on cytokine production and surface marker expression in naïve and LPS-activated THP-1 differentiated monocytes/macrophages

In pregnancy, maternal monocytes and macrophages acquire a specific phenotype that enables them to maintain immune tolerance and facilitate hormone–immune cell interactions, which are necessary for gestational progression. The aim of this study was to determine the effect of pregnancy hormone mixtures of the first and third trimesters on both resting and activated monocytes and macrophages. Pregnancy hormone levels (cortisol, estradiol, progesterone, and prolactin) were quantified at the first and third trimesters. The average of the levels obtained was used to prepare two mixtures of synthetic hormones: low and high. These mixtures were then used to stimulate THP-1 monocytes and macrophages, resting or activated with LPS. Cytokine production in the culture supernatants and surface marker expression (CD14, CD86, and CD163) were evaluated by ELISA and flow cytometry, respectively. We found that the hormones modulated the pro-inflammatory response of THP-1 cells, LPS-activated monocytes, and macrophages, inducing high levels of IL-10 and low levels of IL-8, IL-1-β, and IL-6. All hormone stimulation increased the CD163 receptor in both resting and LPS-activated monocytes and macrophages in a dose-independent manner, unlike CD14 and CD86. Pregnancy hormones promote the expression of the markers associated with the M2-like phenotype, modulating their pro-inflammatory response. This phenotype regulation by hormones could be a determinant in pregnancy.

Overview of procalcitonin in pregnancy and in pre-eclampsia

Procalcitonin (PCT), a precursor for calcitonin, is a prohormone involved in the inflammatory processes, which has been poorly studied in the context of pregnancy. During severe inflammation, PCT derives from almost all cell types, including monocytes and parenchymal tissues, making it a good predictive and diagnostic marker of an inflammatory state with rapidly increased serum levels in inflammation or sepsis. In normal pregnancy, PCT is basally expressed at very low level by decidual cells, even if decidual macrophages, which in normal pregnancy are skewed to M2 macrophages, are resistant to lipopolysaccharide (LPS)-induced production of PCT. As PCT increase is associated with an inflammatory state, several research groups investigated whether PCT can be considered a marker of pre-eclampsia, a pregnancy disease characterized by systemic inflammation. The first aim of this review is to summarize what is already known about the tissues synthesizing PCT, about the stimuli that cause the increase of circulating PCT levels and how PCT acts as a proinflammatory stimulus by itself. Secondly, we will describe the role of this prohormone in normal pregnancy and in pregnancies complicated by pre-eclampsia, highlighting the involvement of the decidual macrophages and the proinflammatory cytokine tumor necrosis factor-α in the modulation of PCT expression in the decidual microenvironment.

Changes in the immune system - the key to diagnostics and therapy of patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is one of the most common pathologies of that organ. The development of the disease involves a variety of mechanisms, including insulin resistance, oxidative stress, endoplasmic reticulum stress, endotoxins from the intestinal flora and genetic predispositions. Additionally, clinical data suggest that the presence of NAFLD is associated with excessive activation of the immune system. For practical purposes, attention should be paid to the moment when the subjects predisposed to NAFLD develop inflammatory infiltration and signs of fibrosis in the liver (non-alcoholic steatohepatitis - NASH). Their presence is an important risk factor for hepatic cirrhosis, hepatic failure, and hepatocellular carcinoma, as well as for the occurrence of cardiovascular events. Regardless of the diagnostic methods used, including laboratory tests and imaging, liver biopsy remains the gold standard to identify and differentiate patients with NAFLD and NASH. The search for other, safer, cheaper and more readily available diagnostic tests is still being continued. Attention has been drawn to the usefulness of markers of immune status of the organism, not only for the diagnosis of NASH, but also for the identification of NAFLD patients at risk of disease progression. Despite the effectiveness of medication, no recommendations have been established for pharmacotherapy of NAFLD. Data indicate the primary need for non-pharmacological interventions to reduce body weight. However, there is evidence of the applicability of certain drugs and dietary supplements, which, by their effect on the immune system, inhibit its excessive activity, thus preventing the progression of NAFLD to NASH.

Pre-eclampsia affects procalcitonin production in placental tissue

PROBLEM

Procalcitonin (PCT) is the prohormone of calcitonin which is usually released from neuroendocrine cells of the thyroid gland (parafollicular) and the lungs (K cells). PCT is synthesized by almost all cell types and tissues, including monocytes and parenchymal tissue, upon LPS stimulation. To date, there is no evidence for PCT expression in the placenta both in physiological and pathological conditions.

METHOD

Circulating and placental PCT levels were analysed in pre-eclamptic (PE) and control patients. Placental cells and macrophages (PBDM), stimulated with PE sera, were analysed for PCT expression. The effect of anti-TNF-α antibody was analysed.

RESULTS

Higher PCT levels were detected in PE sera and in PE placentae compared to healthy women. PE trophoblasts showed increased PCT expression compared to those isolated from healthy placentae. PE sera induced an upregulation of PCT production in macrophages and placental cells. The treatment of PBDM with PE sera in the presence of anti-TNF-α completely abrogated the effect induced by pathologic sera.

CONCLUSION

Trophoblast cells are the main producer of PCT in PE placentae. TNF-α, in association with other circulating factors present in PE sera, upregulates PCT production in macrophages and normal placental cells, thus contributing to the observed increased in circulating PCT in PE sera.

Alternative functions of the complement protein C1q at embryo implantation site

Complement component C1q is one of the recognition molecules of the complement system which can serve several functions unrelated to complement activation. This molecule is produced at foeto-maternal interface by macrophages as wells as by decidual endothelial cells and invading trophoblast. Foetal trophoblast cells migrating through the decidua in the early stages of pregnancy synthesize and express C1q on their surface, which is actively involved in promoting trophoblast endovascular and interstitial invasion of the decidua. These functions are mediated by two cell surface receptors, gC1qR and α4β1 integrin, which promote trophoblast adhesion and migration through the activation of ERK1/2 MAPKs. C1q^-/- mice manifest increased frequency of foetal resorption, reduced foetal weight, and smaller litter size when compared to their wild-type counterparts, suggesting that defective local production of C1q may be involved in pregnancy disorders, such as pre-eclampsia. C1q acts also as a strong angiogenic factor and promotes neovascularization. These studies suggest novel and unexpected roles of this complement component in physiological and pathological pregnancies.