Excessive Neutrophil Activity in Gestational Diabetes Mellitus: Could It Contribute to the Development of Preeclampsia?

The role of neutrophils and neutrophil extracellular traps (NETs) in stages, outcomes and pregnancy complications

Neutrophils are the main components of innate immunity to eliminate infectious pathogens. Neutrophils play a role in several stages of the reproductive cycle, and their presence in the female reproductive system is highly regulated, so their function may change during pregnancy. Emerging evidence suggests that neutrophils are important at all stages of pregnancy, from implantation, placentation, and connective tissue regeneration to birth, as well as birth itself. Neutrophil extracellular traps (NETs) are defined as extracellular strands of unfolded DNA together with histone complexes and neutrophil granule proteins. NET formation is a new mechanism of these cells for their defense function. These strands containing DNA and antimicrobial peptides were initially recognized as one of the defense mechanisms of neutrophils, but later it was explained that they are involved in a variety of non-infectious diseases. Since the source of inflammation and tissue damage is the irregular activity of neutrophils, it is not surprising that NETosis are associated with a number of inflammatory conditions and diseases. The overexpression of NET components or non-principled NET clearance is associated with the risk of production and activation of autoantibodies, which results in participation in autoinflammatory and autoimmune disorders (SLE, RA), fibrosis, sepsis and other disorders such as vascular diseases, for example, thrombosis and atherosclerosis. Recent published articles have shown the role of neutrophils and extracellular traps (NETs) in pregnancy, childbirth and pregnancy-related diseases. The aim of this study was to identify and investigate the role of neutrophils and neutrophil extracellular traps (NETs) in the stages of pregnancy, as well as the complications caused by these cells.

Exosomal small RNA profiling in first-trimester maternal blood explores early molecular pathways of preterm preeclampsia

Introduction

Preeclampsia (PE) is a severe obstetrical syndrome characterized by new-onset hypertension and proteinuria and it is often associated with fetal intrauterine growth restriction (IUGR). PE leads to long-term health complications, so early diagnosis would be crucial for timely prevention. There are multiple etiologies and subtypes of PE, and this heterogeneity has hindered accurate identification in the presymptomatic phase. Recent investigations have pointed to the potential role of small regulatory RNAs in PE, and these species, which travel in extracellular vesicles (EVs) in the circulation, have raised the possibility of non-invasive diagnostics. The aim of this study was to investigate the behavior of exosomal regulatory small RNAs in the most severe subtype of PE with IUGR.

Methods

We isolated exosomal EVs from first-trimester peripheral blood plasma samples of women who later developed preterm PE with IUGR (n=6) and gestational age-matched healthy controls (n=14). The small RNA content of EVs and their differential expression were determined by next-generation sequencing and further validated by quantitative real-time PCR. We also applied the rigorous exceRpt bioinformatics pipeline for small RNA identification, followed by target verification and Gene Ontology analysis.

Results

Overall, >2700 small RNAs were identified in all samples and, of interest, the majority belonged to the RNA interference (RNAi) pathways. Among the RNAi species, 16 differentially expressed microRNAs were up-regulated in PE, whereas up-regulated and down-regulated members were equally found among the six identified Piwi-associated RNAs. Gene ontology analysis of the predicted small RNA targets showed enrichment of genes in pathways related to immune processes involved in decidualization, placentation and embryonic development, indicating that dysregulation of the induced small RNAs is connected to the impairment of immune pathways in preeclampsia development. Finally, the subsequent validation experiments revealed that the hsa_piR_016658 piRNA is a promising biomarker candidate for preterm PE associated with IUGR.

Discussion

Our rigorously designed study in a homogeneous group of patients unraveled small RNAs in circulating maternal exosomes that act on physiological pathways dysregulated in preterm PE with IUGR. Therefore, our small RNA hits are not only suitable biomarker candidates, but the revealed biological pathways may further inform us about the complex pathology of this severe PE subtype.

Severe gestational diabetes mellitus in lean dams is associated with low IL-1α levels and affects the growth of the juvenile mouse offspring

We investigated how maternal gestational diabetes (GDM) impacts the metabolic status of offspring. GDM was induced in CD1 mice consuming a fast-food diet (FFD) by repeated low-dose streptozotocin injections before mating. Offspring of normoglycemic standard chow or the FFD consuming dams served as controls. In 4-week-old offspring weaned to standard chow, plasma concentrations of extracellular DNA, inflammatory markers, and parameters of the cardiometabolic status (glycemia, liver lipid content; body, organ, and fat weight) were determined. Two-factor analysis of variance indicated that the male offspring of GDM dams manifest postnatal growth retardation and lower relative kidney weight. Regardless of sex, GDM offspring manifest the lowest IL-1α levels, and other inflammatory markers showed mild and inconsistent alterations. Offspring of dams consuming the FFD displayed higher liver triacylglycerols content. The three groups of offspring showed no significant differences in glycemia and extracellular DNA. Partial least squares-discriminant analysis indicated that male GDM offspring present lower kidney, body, and brown adipose tissue weights; lower IL-1α levels, and higher concentrations of GM-CSF and IL-10 compared with their FFD counterparts. The model failed to select discriminative variables in females. In conclusion, in mice, maternal GDM in the absence of obesity adversely affects the early growth of juvenile male offspring.

Gestational Diabetes Mellitus and Preeclampsia: Correlation and Influencing Factors

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are common pregnancy complications with similar risk factors and pathophysiological changes. Evidence from previous studies suggests that the incidence of PE is significantly increased in women with GDM, but whether GDM is independently related to the occurrence of PE has remained controversial. GDM complicated by PE further increases perinatal adverse events with greater impact on the future maternal and offspring health. Identify factors associated with PE in women with GDM women, specifically those that are controllable, is important for improving pregnancy outcomes. This paper provides the findings of a review on the correlation between GDM and PE, factors associated with PE in women with GDM, possible mechanisms, and predictive markers. Most studies concluded that GDM is independently associated with PE in singleton pregnancy, and optimizing the treatment and management of GDM can reduce the incidence of PE, which is very helpful to improve pregnancy outcomes.

The regulatory mechanism of neutrophil extracellular traps in cancer biological behavior

As the predominant host defense against pathogens, neutrophil extracellular traps (NETs) have attracted increasing attention due to their vital roles in infectious inflammation in the past few years. Interestingly, NETs also play important roles in noninfectious conditions, such as rheumatism and cancer. The process of NETs formation can be regulated and the form of cell death accompanied by the formation of NETs is regarded as "NETosis". A large amount of evidence has confirmed that many stimuli can facilitate the release of NETs from neutrophils. Furthermore, it has been illustrated that NETs promote tumor growth and progression via many molecular pathways. Meanwhile, NETs also can promote metastasis in many kinds of cancers based on multiple studies. In addition, some researchs have found that NETs can promote coagulation and cancer-associated thrombosis. In the present review, it will highlight how NETosis, which is stimulated by various stimuli and signaling pathways, affects cancer biological behaviors via NETs. Given their crucial roles in cancer, NETs will become possible therapeutic targets for inhibiting proliferation, metastasis and thrombosis in cancer patients.

Mechanism of neutrophil extracellular traps generation and their role in trophoblasts apoptosis in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a metabolic syndrome occurring in pregnant women and increases the risk of placental dysplasia. Neutrophil extracellular traps (NETs) may play a critical role in placental dysplasia. NETosis (neutrophil cell death by NET release) depends on NADPH/ROS pathway. In view of the adiponectin which is widely believed to be reduced in GDM patients suppresses NADPH oxidase and ROS generation of neutrophil. We speculate that increased NET release is associated with hypoadiponectinemia. Trophoblast apoptosis is significantly increased in GDM patients, but it is not clear whether NETs promotes cell apoptosis. This study aims to reveal the mechanism of Neutrophil Extracellular Traps generation and their role in trophoblast apoptosis in Gestational Diabetes Mellitus. We investigated the generation of NETs by cell-free DNA (cf-DNA) quantification, live-cell imaging, and reactive oxygen species (ROS) measurement. ERK1/2 and p38 MAPK signalling pathway proteins were detected by western blotting. The Cell Counting Kit-8 (CCK-8) assay, flow cytometry, and western blotting were performed to explore the effects of NETs on trophoblast apoptosis. We found that adiponectin inhibited NET release by suppressing ROS production, and p38 MAPK and ERK1/2 proteins were involved in the process. Further, NETs promoted trophoblast apoptosis by activating the ROS-dependent mitochondrial pathway, which is mediated by ERK1/2 signalling. The current study demonstrated that hypoadiponectinemia is the cause of NETs formation and NETs promoting trophoblast apoptosis.

Neutrophil Recruitment and Participation in Severe Diseases Caused by Flavivirus Infection

Neutrophils are first-line responders to infections and are recruited to target tissues through the action of chemoattractant molecules, such as chemokines. Neutrophils are crucial for the control of bacterial and fungal infections, but their role in the context of viral infections has been understudied. Flaviviruses are important human viral pathogens transmitted by arthropods. Infection with a flavivirus may result in a variety of complex disease manifestations, including hemorrhagic fever, encephalitis or congenital malformations. Our understanding of flaviviral diseases is incomplete, and so is the role of neutrophils in such diseases. Here we present a comprehensive overview on the participation of neutrophils in severe disease forms evolving from flavivirus infection, focusing on the role of chemokines and their receptors as main drivers of neutrophil function. Neutrophil activation during viral infection was shown to interfere in viral replication through effector functions, but the resulting inflammation is significant and may be detrimental to the host. For congenital infections in humans, neutrophil recruitment mediated by CXCL8 would be catastrophic. Evidence suggests that control of neutrophil recruitment to flavivirus-infected tissues may reduce immunopathology in experimental models and patients, with minimal loss to viral clearance. Further investigation on the roles of neutrophils in flaviviral infections may reveal unappreciated functions of this leukocyte population while increasing our understanding of flaviviral disease pathogenesis in its multiple forms.

Gestational diabetes mellitus and inflammatory biomarkers of neutrophil-lymphocyte ratio and platelet-lymphocyte ratio: a systematic review and meta-analysis

PURPOSE

To evaluate the association between two inflammatory biomarkers of neutrophil -lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) with gestational diabetes mellitus (GDM).

METHODS AND MATERIALS

Systematic search was performed up to June 2020 in databases such as PubMed, Embase, Scopus, Web of Science, and Google scholar. The random-effects model was utilised to combine the weighted mean differences (WMDs) and their 95% confidence intervals (CIs).

RESULTS

Out of a total of 849 articles, sixteen studies were eligible. Our findings indicated higher NLR (WMD = 0.48, 95% CI: 0.25, 0.71) and PLR (WMD = 8.22, 95% CI: -0.50, 16.94) values in pregnancies diagnosed with GDM compared with non-GDM control pregnancies. However, the difference in PLR value did not reach a statistically significant level (Z = 1.85, p = 0.065). In meta-regression analysis, we found no significant influence of total sample size [for NLR (B= -0.0, p = 0.13), for PLR (B= -0.02, p = 0.55)] and publication year [for NLR (B= -0.02, p = 0.61), for PLR (B = 0.89, p = 0.75)] on association between NLR and PLR with GDM.

CONCLUSION

The current meta-analysis is the first, to our knowledge, to show that NLR value is significantly associated with GDM. However, PLR showed no significant association with GDM.

Gestational Diabetes Mellitus and Maternal Immune Dysregulation: What We Know So Far

Gestational diabetes mellitus (GDM) is an obstetric complication that affects approximately 5-10% of all pregnancies worldwide. GDM is defined as any degree of glucose intolerance with onset or first recognition during pregnancy, and is characterized by exaggerated insulin resistance, a condition which is already pronounced in healthy pregnancies. Maternal hyperglycaemia ensues, instigating a 'glucose stress' response and concurrent systemic inflammation. Previous findings have proposed that both placental and visceral adipose tissue play a part in instigating and mediating this low-grade inflammatory response which involves altered infiltration, differentiation and activation of maternal innate and adaptive immune cells. The resulting maternal immune dysregulation is responsible for exacerbation of the condition and a further reduction in maternal insulin sensitivity. GDM pathology results in maternal and foetal adverse outcomes such as increased susceptibility to diabetes mellitus development and foetal neurological conditions. A clearer understanding of how these pathways originate and evolve will improve therapeutic targeting. In this review, we will explore the existing findings describing maternal immunological adaption in GDM in an attempt to highlight our current understanding of GDM-mediated immune dysregulation and identify areas where further research is required.

Proteomic identification of Placental Protein 1 (PP1), PP8, and PP22 and characterization of their placental expression in healthy pregnancies and in preeclampsia

INTRODUCTION

Placental Protein 1 (PP1), PP8, and PP22 were isolated from the placenta. Herein, we aimed to identify PP1, PP8, and PP22 proteins and their placental and trophoblastic expression patterns to reveal potential involvement in pregnancy complications.

METHODS

We analyzed PP1, PP8, and PP22 proteins with LC-MS. We compared the placental behaviors of PP1, PP8, and PP22 to the predominantly placenta-expressed PP5/TFPI-2. Placenta-specificity scores were generated from microarray data. Trophoblasts were isolated from healthy placentas and differentiated; total RNA was isolated and subjected to microarray analysis. We assigned the placentas to the following groups: preterm controls, early-onset preeclampsia, early-onset preeclampsia with HELLP syndrome, term controls, and late-onset preeclampsia. After histopathologic examination, placentas were used for tissue microarray construction, immunostaining with anti-PP1, anti-PP5, anti-PP8, or anti-PP22 antibodies, and immunoscoring.

RESULTS

PP1, PP8, and PP22 were identified as 'nicotinate-nucleotide pyrophosphorylase', 'serpin B6', and 'protein disulfide-isomerase', respectively. Genes encoding PP1, PP8, and PP22 are not predominantly placenta-expressed, in contrast with PP5. PP1, PP8, and PP22 mRNA expression levels did not increase during trophoblast differentiation, in contrast with PP5. PP1, PP8, and PP22 immunostaining were detected primarily in trophoblasts, while PP5 expression was restricted to the syncytiotrophoblast. The PP1 immunoscore was higher in late-onset preeclampsia, while the PP5 immunoscore was higher in early-onset preeclampsia.

DISCUSSION

PP1, PP8, and PP22 are expressed primarily in trophoblasts but do not have trophoblast-specific regulation or functions. The distinct dysregulation of PP1 and PP5 expression in either late-onset or early-onset preeclampsia reflects different pathophysiological pathways in these preeclampsia subsets.

Clinical significance of neutrophil-lymphocyte ratio and monocyte-lymphocyte ratio in women with hyperglycemia

Objective: Abnormal pro-inflammatory regulation of the immune system might contribute to the pathogenesis of hyperglycemia during pregnancy. We examined the correlations of neutrophil-lymphocyte ratio (NLR) and monocyte-lymphocyte ratio (MLR) with disease severity and assessed their predictive values. Methods: This retrospective case-control study included 311 cases of hyperglycemia first detected during pregnancy (HFDP) [153 with gestational diabetes mellitus (GDM) and 158 with diabetes in pregnancy (DIP)] and, as a control group, 172 pregnant women with normal glucose tolerance. The NLRs and MLRs were calculated from the blood test data. Results: The absolute leukocyte, neutrophil, monocyte, and lymphocyte counts as well as the NLR and MLR values of HFDP patients significantly differed from control values, but no significant differences were detected in the leukocyte, neutrophil, and monocyte counts of the GDM and DIP groups. Significantly different metrics were selected, binary analysis performed, and odds ratios calculated to identify risk factors. Age, BMI, NLR, and MLR were found to be risk factors for HFDP, and high systolic blood pressure (SBP) at triage and MLR related to the occurrence of DIP. Receiver operating characteristics curve analysis showed that NLR and MLR had better diagnostic accuracy in distinguishing HFDP from controls [NLR area under the curve (AUC) = 0.78; MLR AUC = 0.72] than age and BMI. Values for NLR > 4.394 or MLR > 0.309 correlated with the severity of maternal clinical symptoms and perinatal infant outcomes. MLR was the best predictor of DIP (AUC = 0.72) and MLR values > 0.299 could identify patients at risk for developing DIP and having poor fetal outcomes. Conclusion: Metrics derived from peripheral blood neutrophil, monocyte, and lymphocyte counts are thought to reflect systemic immune-inflammation. Elevated MLR and NLR may be unfavorable prognostic factors for clinical outcomes in patients with hyperglycemia during pregnancy.

Unveiling the pathophysiology of gestational diabetes: Studies on local and peripheral immune cells

Gestational diabetes mellitus (GDM) has been associated with impaired maternal immune response. Our aim was to review the available literature linking immune cells profile to GDM, in order to comprehend the role that different subpopulations play in the development of this pathology. We searched in PubMed for studies published in the last decade on circulating levels and placenta expression of immune cells on GDM. We identified 18 studies with several differences regarding the study design, clinical characteristics, number of participants, cell subpopulation and type of sample. Most studies assessed only one subpopulation either in peripheral blood or placenta and did not analyse functional properties of the cells. The most frequently evaluated immune cells were T lymphocytes, especially regulatory T (Tregs), and natural killer (NK) cells in the peripheral blood, and placental macrophages. No studies analysing B cells were identified, and only one study each evaluating γδT cells, dendritic cell (DC) and monocytes was found. Although there are controversies, at least one study reported positive association between GDM and CD4⁺ (activated), Tregs, Th17 and γδT cells; neutrophil/lymphocyte; NK cell (cytotoxic); macrophages; and monocytes. The number of studies is still small, so caution should be exercised in interpreting the data, and further research is required to validate these findings and establish the role of adaptive and innate immune cells in GDM pathophysiology.

Expression and correlation of Chemerin and FABP4 in peripheral blood of gestational diabetes mellitus patients

Expression and correlation of Chemerin and fatty acid-binding protein 4 (FABP4) in peripheral blood of gestational diabetes mellitus (GDM) patients were investigated. Sixty patients with GDM from March 2018 to March 2019 in the People's Hospital of Zhangqiu Area were selected as the study group (SG) and another 50 healthy pregnant women corresponding to their age and pregnancy were selected as the control group (CG). Enzyme linked immunosorbent assay (ELISA) was used to detect the expression of Chemerin and FABP4 in serum. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of Chemerin and FABP4 in peripheral blood for GDM patients. Pearson's correlation coefficient was used to analyze the correlation between Chemerin and FABP4 and the correlation between Chemerin and inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Expression of Chemerin and FABP4 in peripheral blood of GDM patients were significantly higher than those in CG. The AUC of GDM patients diagnosed with Chemerin and FABP4 in peripheral blood was 0.820 and 0.814, while the AUC of GDM patients diagnosed with Chemerin combined with FABP4 in peripheral blood was 0.904. Expression of inflammatory factors IL-6 and TNF-α in the SG were significantly higher than those in the CG. Chemerin in the SG was positively correlated with FABP4 and positively correlated with inflammatory factors IL-6 and TNF-α. Patients with advanced age (≥35 years), family history of diabetes, hyperlipidemia, high pre-pregnancy BMI, high fasting blood glucose, high Chemerin and high FABP4 expression have high risk of GDM. In conclusion, Chemerin and FABP4 were upregulated in the peripheral blood of GDM patients. There was a positive correlation between the two and a positive correlation with the inflammatory factors IL-6 and TNF-α.

Exosomes-Associated DNA-New Marker in Pregnancy Complications?

Despite a large number of studies, the etiology of pregnancy complications remains unknown. The involvement of cell-free DNA or fetal cell-free DNA in the pathogenesis of pregnancy complications is currently being hypothesized. Cell-free DNA occurs in different forms-free; part of neutrophil extracellular traps; or as recently discovered, carried by extracellular vesicles. Cell-free DNA is believed to activate an inflammatory pathway, which could possibly cause pregnancy complications. It could be hypothesized that DNA in its free form could be easily degraded by nucleases to prevent the inflammatory activation. However, recently, there has been a growing interest in the role of exosomes, potential protectors of cell-free DNA, in pregnancy complications. Most of the interest from recent years is directed towards the micro RNA carried by exosomes. However, exosome-associated DNA in relation to pregnancy complications has not been truly studied yet. DNA, as an important cargo of exosomes, has been so far studied mostly in cancer research. This review collects all the known information on the topic of not only exosome-associated DNA but also some information on vesicles-associated DNA and the studies regarding the role of exosomes in pregnancy complications from recent years. It also suggests possible analysis of exosome-associated DNA in pregnancy from plasma and emphasizes the importance of such analysis for future investigations of pregnancy complications. A major obstacle to the advancement in this field is the proper uniformed technique for exosomes isolation. Similarly, the sensitivity of methods analyzing a small fraction of DNA, potentially fetal DNA, carried by exosomes is variable.

The role of neutrophil activation in determining the outcome of pregnancy and modulation by hormones and/or cytokines

Neutrophils are often exclusively considered as a first-line innate immune defence, able to rapidly kill or trap pathogens and causing in case of over-activation tissue damage. In the female reproductive tract, however, the presence and activity of neutrophils seems to be tightly regulated. Major players in orchestrating this regulation are cyclical steroid sex hormones present during the menstrual cycle and pregnancy. This review describes the role of sex hormones in regulating directly or indirectly the functionality of neutrophils, the role of neutrophils during fertilization and pregnancy and in controlling viral, fungal and bacterial infection. This review also discusses the consequence of overt neutrophil activation in pregnancy pathologies.