Preconceptual leptin levels in gestational diabetes and hypertensive pregnancy

Mid-late gestation leptin infusion induces placental mitochondrial and endoplasmic reticulum unfolded protein responses in a mouse model of preeclampsia

INTRODUCTION

Preeclamptic patients, both lean and obese, present with elevated leptin levels which are associated with the development of maternal endothelial dysfunction and adverse fetal outcomes, such as growth restriction, leading to low birth weight. Recent studies in pregnant mice demonstrate that mid-late gestation leptin infusion induces clinical characteristics of preeclampsia, including elevated maternal blood pressure, maternal endothelial dysfunction and fetal growth restriction. However, whether leptin triggers placental stress responses that contribute to adverse fetal outcomes as in preeclampsia is unknown.

METHODS

In the current study we measured the expression of proteins involved in the endoplasmic reticulum (UPRer) and mitochondrial (UPRmt) unfolded protein responses in placentas of wild-type sham normal pregnant and leptin-infused preeclamptic mice.

RESULTS

The data show that mid-late gestation leptin infusion induced activation of indices of placental UPRer and UPRmt, while reducing placental repair mechanisms to UPRmt in preeclamptic mice. Mid-late gestation infusion with leptin upregulated markers of placental oxidative stress, reduced the placental expression levels of mitochondrial electron transport chain complexes I and II and increased the expression of placental endothelin-1 (ET-1) in preeclamptic mice. The leptin-induced activation of several placental UPRmt markers as well as ET-1 levels correlated with fetal growth restriction and impaired maternal endothelial function in preeclamptic mice.

DISCUSSION

Collectively, these data indicate that elevated levels of leptin in mid-late pregnancy in mice promote placental stress responses, akin to those in pregnant women with preeclampsia.

Probiotic therapy as a promising strategy for gestational diabetes mellitus management

INTRODUCTION

Gestational diabetes mellitus (GDM) has become the most common pregnancy medical complication, and its prevalence has increased in recent years. The GDM treatment primarily relies on adopting healthy eating habits, physical exercise, and insulin therapy. However, using probiotics to modulate the gut microbiota has been the subject of clinical trials as a promising therapeutic strategy for GDM management.

AREAS COVERED

Due to the adverse effects of gut dysbiosis in women with GDM, strategies targeting the gut microbiota to mitigate hyperglycemia, low-grade inflammation, and adverse pregnancy outcomes have been explored. Probiotic supplementation may improve glucose metabolism, lipid profile, oxidative stress, inflammation, and blood pressure in women with GDM. Furthermore, decreased fasting blood glucose, insulin resistance, and inflammatory markers, such as TNF-α and CRP, as well as increased total antioxidant capacity, lipid profile modulation, and improved blood pressure in women with GDM, are some of the important results reported in the available literature.

EXPERT OPINION

To fill the knowledge gap, further studies are needed focusing on modulating gut microbiota composition and metabolic activity and their systemic repercussions in GDM.

Implications of pregnancy on cardiometabolic disease risk: preeclampsia and gestational diabetes

Cardiometabolic disorders, such as obesity, insulin resistance, and hypertension, prior to and within pregnancy are increasing in prevalence worldwide. Pregnancy-associated cardiometabolic disease poses a great risk to the short- and long-term well-being of the mother and offspring. Hypertensive pregnancy, notably preeclampsia, as well as gestational diabetes are the major diseases of pregnancy growing in prevalence as a result of growing cardiometabolic disease prevalence. The mechanisms whereby obesity, diabetes, and other comorbidities lead to preeclampsia and gestational diabetes are incompletely understood and continually evolving in the literature. In addition, novel therapeutic avenues are currently being explored in these patients to offset cardiometabolic-induced adverse pregnancy outcomes in preeclamptic and gestational diabetes pregnancies. In this review, we discuss the emerging pathophysiological mechanisms of preeclampsia and gestational diabetes in the context of cardiometabolic risk as well as the most recent preclinical and clinical updates in the pathogenesis and treatment of these conditions.

Both endothelial mineralocorticoid receptor expression and hyperleptinemia are required for clinical characteristics of placental ischemia in mice

One of the initiating events in preeclampsia (PE) is placental ischemia. Rodent models of placental ischemia do not present with vascular endothelial dysfunction, a hallmark of PE. We previously demonstrated a role for leptin in endothelial dysfunction in pregnancy in the absence of placental ischemia. We hypothesized that placental ischemia requires hyperleptinemia and endothelial mineralocorticoid receptor (ECMR) expression to induce PE-associated endothelial dysfunction in pregnant mice. We induced placental ischemia via the reduced uterine perfusion pressure (RUPP) procedure in pregnant ECMR-intact (ECMR+/+) and ECMR deletion (ECMR-/-) mice at gestational day (GD) 13. ECMR+/+ RUPP pregnant mice also received concurrent leptin infusion via miniosmotic pump (0.9 mg/kg/day). RUPP increased blood pressure via radiotelemetry and decreased fetal growth in ECMR+/+ pregnant mice. Both increases in blood pressure and reduced fetal growth were abolished in RUPP ECMR-/- mice. Placental ischemia did not decrease endothelial-dependent relaxation to acetylcholine (ACh) but increased phenylephrine (Phe) contraction in mesenteric arteries of pregnant mice, which was ablated by ECMR deletion. Addition of leptin to RUPP mice significantly reduced ACh relaxation in ECMR+/+ pregnant mice, accompanied by an increase in soluble FMS-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PLGF) ratio. In conclusion, our data indicate that high leptin levels drive endothelial dysfunction in PE and that ECMR is required for clinical characteristics of hypertension and fetal growth restriction in placental ischemia PE. Collectively, we show that both ECMR and leptin play a role to mediate PE.NEW & NOTEWORTHY Leptin is a key feature of preeclampsia that initiates vascular endothelial dysfunction in preeclampsia characterized by placental ischemia. Endothelial mineralocorticoid receptor (ECMR) deletion in placental ischemia protects pregnant mice from elevations in blood pressure and fetal growth restriction in pregnancy. Increases in leptin production mediate the key pathological feature of endothelial dysfunction in preeclampsia in rodents. ECMR activation contributes to the increase in blood pressure and fetal growth restriction in preeclampsia.

The association between leptin and diabetes: A meta-analysis

PURPOSE

The study object was to determine the relationship between leptin and diabetes.

METHODS

We searched for the literature on the relationship between leptin and diabetes from PubMed, EMBASE, Cochrane Library, and CNKI databases. We carried out the meta-analysis by calculating the Std. Mean Difference (SMD) and 95% confidence intervals (CIs) to study the relationship between leptin and diabetes. We performed the Chi-square-based Q test and I2 statistics to evaluate the potential heterogeneity, and the sensitivity analysis was performed to evaluate the stability of our results. Moreover, Begg's test was performed to evaluate the publication bias.

RESULTS

There are 10 studies in this study for meta-analysis, which include 1879 patients (diabetic (n = 1024); and nondiabetic patients (n = 855)). The results indicated that the levels of serum leptin were significantly increased in patients with diabetes (SMD = 1.78, 95% CI [0.81, 2.76]), especially those with gestational diabetes mellitus compared with controls (SMD = 3.03, 95% CI [1.21, 4.86]). However, the results showed that there was no difference in serum leptin levels between type 2 diabetes and controls (SMD = 0.34, 95% CI [-1.06, 1.74]).

CONCLUSIONS

Our analysis indicated that the levels of serum leptin were significantly elevated in patients with diabetes especially those with gestational diabetes mellitus compared with controls.

Progress in Research on Biomarkers of Gestational Diabetes Mellitus and Preeclampsia

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are common complications in pregnancy, with incidence rates of 1-5% and 9.4%, respectively, in China. Both these phenomena can cause adverse pregnancy outcomes and are extremely harmful to the mother and fetus. In this study, we observed that several predictive factors have important value in GDM and PE. Among the GDM group, abnormal levels of adiponectin (APN), C-reactive protein (CRP), and Leptin were observed. The coexistence of PE and GDM in the pregnant population is not uncommon. Ultimately, we discovered abnormal levels of factors such as Visfatin, Advanced oxidative protein product (AOPP), Fibroblast growth factor 21 (FGF21), and resistin in both GDM and PE groups. Particularly, the FGF21 factor holds significant importance in our research. Therefore, we need to complete the analysis and discussion of relevant predictive factors to enable early prediction and disease monitoring of GDM, PE, and other pregnancy-related disorders, ultimately contributing to the long-term health of pregnant women.

Role of leptin in the pathophysiology of preeclampsia

Preeclampsia (PE) is a severe pregnancy complication. The exact pathogenesis of PE remains unclear, but it is related to immune, inflammatory, circulatory, and oxidative stress factors. Leptin is a protein involved in these processes and is essential for maintaining a normal pregnancy and healthy fetal growth. Abnormal increases in leptin levels have been observed in the peripheral blood and placenta of patients with PE. Disturbances in leptin can affect the proliferation and hypertrophy of vascular smooth muscle cells, which are important for placentation. Leptin also regulates arterial tension and trophoblast function in pregnant women. In addition, consistently high levels of leptin are linked to hyperactive inflammation and oxidative stress reactions in both patients with PE and animal models. This review focuses on the role of leptin in the pathophysiology of PE and elucidates its potential mechanisms.

Mechanisms of leptin-induced endothelial dysfunction

PURPOSE OF REVIEW

Endothelial dysfunction is a major risk factor for many cardiovascular diseases, notably hypertension. Obesity increases the risk of endothelial dysfunction in association with increasing production of the adipokine leptin. Preclinical studies have begun to unravel the mechanisms whereby leptin leads to the development of endothelial dysfunction, which are sex-specific. This review will summarize recent findings of mechanisms of leptin-induced endothelial impairment in both male and females and in pregnancy.

RECENT FINDINGS

Leptin receptors are found in high concentrations in the central nervous system (CNS), via which leptin promotes appetite suppression and upregulates sympathetic nervous system activation. However, leptin receptors are expressed in many other tissues, including the vascular endothelial cells and smooth muscle cells. Recent studies in mice with vascular endothelial or smooth muscle-specific knockdown demonstrate that endothelial leptin receptor activation plays a protective role against endothelial dysfunction in male animals, but not necessarily in females. Clinical studies indicate that women may be more sensitive to obesity-associated vascular endothelial dysfunction. Emerging preclinical data indicates that leptin and progesterone increase aldosterone production and endothelial mineralocorticoid receptor activation, respectively. Furthermore, decades of clinical studies indicate that leptin levels increase in the hypertensive pregnancy disorder preeclampsia, which is characterized by systemic endothelial dysfunction. Leptin infusion in mice induces the clinical characteristics of preeclampsia, including endothelial dysfunction.

SUMMARY

Novel preclinical data indicate that the mechanisms whereby leptin promotes endothelial dysfunction are sex-specific. Leptin-induced endothelial dysfunction may also play a role in hypertensive pregnancy as well.

Association of LEPTIN and other inflammatory markers with preeclampsia: A systematic review

Background: Preeclampsia is a serious pregnancy complication that affects 5%–10% of the obstetric population.

Objective: To study inflammatory markers associated with preeclampsia.

Search Strategy: Searches of articles on the topic published over a 10-year period (2009–2019) were performed in three databases (PubMed, Cochrane, and Embase) using the keywords preeclampsia and inflammatory markers. The PubMed search using 10 years and humans as filters retrieved 124 articles. Using an advanced search strategy, 0 articles were identified in Embase and 10 articles in Cochrane. After screening and eligibility assessment, 13 articles were included in the systematic review and meta-analysis. Meta-analysis and quality assessment of the studies were performed using the Review Manager 5.3 program.

Results: For meta-analysis, women with preeclampsia were compared to control women, i.e., pregnancies without arterial hypertension. Leptin levels were significantly higher (p < 0.0002) in women with preeclampsia compared to controls. Total cholesterol was also significantly elevated in women with preeclampsia (p < 0.0001). There was no significant difference in HDL between groups, but women with preeclampsia had significantly increased LDL (p < 0.01). The same was observed for triglycerides, which were significantly increased in women with preeclampsia (p < 0.04) compared to controls. Analysis of TNF-alpha, an important inflammatory marker, showed higher levels in women with preeclampsia (p < 0.03) compared to controls. The same was observed for another important inflammatory marker, interleukin 6, which was significantly increased in women with preeclampsia (p < 0.0002). There was a significant increase of C-reactive protein in women with preeclampsia (p < 0.003) compared to controls.

Conclusion: Women with preeclampsia have increased levels of inflammatory markers compared to control women.