Visceral Adipose Tissue Inflammatory Factors (TNF-Alpha, SOCS3) in Gestational Diabetes (GDM): Epigenetics as a Clue in GDM Pathophysiology

Circulating Inflammatory Cytokines and Female Reproductive Diseases: A Mendelian Randomization Analysis

CONTEXT

Extensive studies have provided considerable evidence suggesting the role of inflammation in the development of female reproductive diseases. However, causality has not been established.

OBJECTIVE

To explore whether genetically determined circulating levels of cytokines are causally associated with female reproductive diseases and discover potential novel drug targets for these diseases.

METHODS

Instrumental variables (IVs) for 47 circulating cytokines were obtained from a genome-wide association study (GWAS) meta-analysis of 31 112 European individuals. Protein quantitative trait loci and expression quantitative trait loci close to genes served as our IVs. Summary data of 9 female reproductive diseases were mainly derived from GWAS meta-analysis of the UK biobank and FinnGen. We elevated the association using the Wald ratio or inverse variance-weighted Mendelian randomization (MR) with subsequent assessments for MR assumptions in several sensitivity and colocalization analyses. We consider a false discovery rate <0.05 as statistical significance in MR analyses. Replication studies were conducted for further validation, and phenome-wide association studies were designed to explore potential side effects.

RESULTS

Our results indicated that high levels of macrophage colony-stimulating factor (MCSF), growth-regulated oncogene-alpha (GROα), and soluble intercellular adhesion molecule-1 were associated with increased risks of endometriosis, female infertility, and pre-eclampsia, respectively. High platelet-derived growth factor-BB (PDGF-BB) levels that reduced the risk of ovarian aging were also supported. Replication analysis supported the relationship between GROα and female infertility, and between MCSF and endometriosis.

CONCLUSION

We identified 4 correlated pairs that implied potential protein drug targets. Notably, we preferred highlighting the value of PDGF-BB as a drug target for ovarian aging, and MCSF as a drug target for endometriosis.

Research Note: Heat stress affects immune and oxidative stress indices of the immune organs of broilers by changing the expressions of adenosine triphosphate-binding cassette subfamily G member 2, sodium-dependent vitamin C transporter-2, and mitochondrial calcium uniporter

This study aimed to determine the mechanisms of heat-induced oxidative stress in the thymus and spleen of broilers. After 28 d, 30 broilers were randomly divided into the control (25°C ± 2°C; 24 h/d) and heat-stressed (36°C ± 2°C; 8 h/d) groups; the experiment lasted for 1 wk. The broilers in each group were euthanized, and some samples were collected and analyzed at 35 d. The results showed that the birds subjected to heat stress reduced the weight (P < 0.01) and the indices of thymus (P < 0.01), the activities of T-AOC (P < 0.01) and SOD (P < 0.05) of spleen, and levels of IL-10 (P < 0.05) and the GSH-PX (P < 0.05) in thymus and spleen, and increased the IL-6 content of thymus (P < 0.05), the MDA content (P < 0.01), and the reactive oxygen species (ROS) levels (P < 0.01) in thymus and spleen. Moreover, the expression of the IgG gene in the thymus and spleen of heat-stressed broilers was increased (P < 0.05); however, the expression of the IgM gene in the spleen was increased (P < 0.05), with no difference (P > 0.05) in the thymus of heat-stressed broilers compared with the control. Furthermore, the relative expression of adenosine triphosphate-binding cassette subfamily G member 2 (ABCG2) in the thymus and spleen both increased (P < 0.05). The sodium-dependent vitamin C transporter-2 (SVCT-2) (P < 0.01) and mitochondrial calcium uniporter (MCU) (P < 0.01) mRNA levels in the thymus of heat-stressed broilers increased, and the expression of ABCG2 (P < 0.05), SVCT-2 (P < 0.01), and MCU (P < 0.01) proteins in the thymus and spleen of heat-stressed broilers increased compared with the control group. This study confirmed that heat stress-induced oxidative stress in the immune organs of broilers, further reducing immune function.

The circadian rhythm: an influential soundtrack in the diabetes story

Type 2 Diabetes Mellitus (T2DM) has been the main category of metabolic diseases in recent years due to changes in lifestyle and environmental conditions such as diet and physical activity. On the other hand, the circadian rhythm is one of the most significant biological pathways in humans and other mammals, which is affected by light, sleep, and human activity. However, this cycle is controlled via complicated cellular pathways with feedback loops. It is widely known that changes in the circadian rhythm can alter some metabolic pathways of body cells and could affect the treatment process, particularly for metabolic diseases like T2DM. The aim of this study is to explore the importance of the circadian rhythm in the occurrence of T2DM via reviewing the metabolic pathways involved, their relationship with the circadian rhythm from two perspectives, lifestyle and molecular pathways, and their effect on T2DM pathophysiology. These impacts have been demonstrated in a variety of studies and led to the development of approaches such as time-restricted feeding, chronotherapy (time-specific therapies), and circadian molecule stabilizers.

Evaluating the Adipose Tissue Depth as a Predictor Factor for Gestational Diabetes in Later Pregnancy-A Systematic Review

The increasing prevalence of gestational diabetes mellitus (GDM) requires non-invasive and precise techniques for evaluating the predisposing risk factors such as visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). According to PRISMA, we developed a systematic review and searched after "visceral adipose tissue AND gestational diabetes" and identified 221 articles on the MEDLINE and Word of Science databases. After assessing them for inclusion criteria and two researchers screened them, 11 relevant articles were included. Although evidence is conflicting, more studies favor using US-determined VAT in GDM prediction. VAT may be more valuable than body mass index or SAT in predicting GDM. VAT can represent an additive factor to the prediction tool of the risk of developing GDM when used in conjunction with other anthropometric or biological parameters or maternal risk factors. US measurements are heterogeneous given different evaluation techniques, cut-off values and inter-operator variation. A significant limitation is the lack of a gold standard to identify GDM confidently. Pregnant women may benefit from early monitoring and preventive care if classified as high risk for GDM early in the gestational period. US-measured VAT during the first trimester of pregnancy seems a valuable and inexpensive screening approach to predict GDM development later in pregnancy, either by itself or if used in conjunction with other clinical and biological parameters.

Differential Expression of FXR and Genes Involved in Inflammation and lipid Metabolism Indicate Adipose Tissue Dysfunction in Gestational Diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) is the most frequent metabolic alteration in pregnancy. Several abnormalities in visceral adipose tissue (VAT) have been described as part of its pathophysiology including hypertrophy, inflammation and altered lipid metabolism. Farnesoid X receptor (FXR) is involved in adipocyte physiology and inflammation, so its expression may correlate with the expression of tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), lipoprotein lipase (LPL), and two fatty acid transporters (SLC27A2, and SLC27A4).

AIM

To compare the FXR, LPL, SLC27A2, SLC27A4, TNF-α, and IL-10 mRNA expression in VAT between women with GDM and healthy pregnant (HP) women. Secondarily, to evaluate the potential correlation between these expression levels.

MATERIALS AND METHODS

Cross-sectional study of 50 GDM and 50 HP women. Conventional biochemical tests were performed and relative mRNA expression in VAT was measured by RT-qPCR.

RESULTS

Gene expression levels of FXR and IL-10 were lower, whereas those of LPL, as well as the TNF-α/IL-10 ratio, were higher in women with GDM compared to HP. Pre-pregnancy BMI was the main significant independent variable for FXR levels in VAT from women with GDM. In all women, LPL expression levels correlated positively with those of SLC27A2. Only in women with GDM, IL-10 expression levels correlated negatively with those of SLC27A2, and SLC27A4.

CONCLUSIONS

GDM is associated with decreased expression of FXR and IL-10 and increased expression of LPL, as well as a higher TNF/IL-10 ratio in VAT. These results suggest increased lipid storage and pro-inflammatory state indicating VAT dysfunction in this metabolic disorder.

Maternal and Placental DNA Methylation Changes Associated with the Pathogenesis of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is an important metabolic complication of pregnancy, which affects the future health of both the mother and the newborn. The pathogenesis of GDM is not completely clear, but what is clear is that with the development and growth of the placenta, GDM onset and blood glucose is difficult to control, while gestational diabetes patients' blood glucose drops and reaches normal after placenta delivery. This may be associated with placental secretion of insulin-like growth factor, adipokines, tumor necrosis factor-α, cytokines and insulin resistance. Therefore, endocrine secretion of placenta plays a key role in the pathogenesis of GDM. The influence of DNA methylation of these molecules and pathway-related genes on gene expression is also closely related to the pathogenesis of GDM. Here, this review attempts to clarify the pathogenesis of GDM and the related maternal and placental DNA methylation changes and how they affect metabolic pathways.

New Insights into Adipokines in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is the most common metabolic disorder of pregnancy and has considerable short- and long-term consequences for the health of both the mother and the newborn. Within its pathophysiology, genetic, nutritional, epigenetic, immunological, and hormonal components have been described. Within the last two items, it is known that different hormones and cytokines secreted by adipose tissue, known collectively as adipokines, are involved in the metabolic alterations underlying GDM. Although the maternal circulating profile of adipokines in GDM has been extensively studied, and there are excellent reviews on the subject, it is in recent years that more progress has been made in the study of their expression in visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), placenta, and their concentrations in the umbilical circulation. Thus, this review compiles and organizes the most recent findings on the maternal and umbilical circulating profile and the levels of expression of adipokines in VAT, SAT, and placenta in GDM.

Maternal body mass index is associated with an altered immunological profile at 28 weeks of gestation

Healthy pregnancy is accompanied by various immunological and metabolic adaptations. Maternal obesity has been implicated in adverse pregnancy outcomes such as miscarriage, preeclampsia, and gestational diabetes mellitus (GDM), while posing a risk to the neonate. There is a lack of knowledge surrounding obesity and the maternal immune system. The objective of this study was to consider if immunological changes in pregnancy are influenced by maternal obesity. Peripheral blood was collected from fasted GDM-negative pregnant women at 26-28 weeks of gestation. Analysis was done using immunoassay, flow cytometry, bioenergetics analysis, and cell culture. The plasma profile was significantly altered with increasing BMI, specifically leptin (r = 0.7635), MCP-1 (r = 0.3024), and IL-6 (r = 0.4985). Circulating leukocyte populations were also affected with changes in the relative abundance of intermediate monocytes (r = -0.2394), CD4:CD8 T-cell ratios (r = 0.2789), and NKT cells (r = -0.2842). Monocytes analysed in more detail revealed elevated CCR2 expression and decreased mitochondrial content with increased BMI. However, LPS-stimulated cytokine production and bioenergetic profile of PBMCs were not affected by maternal BMI. The Th profile skews towards Th17 with increasing BMI; Th2 (r = -0.3202) and Th9 (r = -0.3205) cells were diminished in maternal obesity, and CytoStim™-stimulation exacerbates IL-6 (r = 0.4166), IL-17A (r = 0.2753), IL-17F (r = 0.2973), and IL-22 (r = 0.2257) production with BMI, while decreasing IL-4 (r = -0.2806). Maternal obesity during pregnancy creates an inflammatory microenvironment. Successful pregnancy requires Th2-biased responses yet increasing maternal BMI favours a Th17 response that could be detrimental to pregnancy. Further research should investigate key populations of cells identified here to further understand the immunological challenges that beset pregnant women with obesity.

NLRP3 inflammasome activation in gestational diabetes mellitus placentas is associated with hydrogen sulfide synthetase deficiency

The placenta may play a key role in the activation of inflammation and initiation of insulin resistance (IR) during gestational diabetes mellitus (GDM) pathogenesis. Interleukin (IL)-1β and IL-18, regulated by NLR family pyrin domain containing-3 (NLRP3) inflammasome, are important inflammatory cytokines in the initiation of maternal IR during GDM. However, the mechanism responsible for the regulatory of NLRP3 inflammasome in placenta remains unknown. Hydrogen sulfide (H₂S) exerts anti-inflammatory function partially via suppressing the activation of the NLPR3 inflammasome. The present study aimed to investigate the role of NLRP3 inflammasome, H₂S synthetase cystathionine-γ-lyase (CSE) and cystathionine-β-synthetase (CBS) in placenta in the pathogenesis of GDM. Clinical placenta samples were collected from pregnant women with GDM (n=16) and healthy pregnant women at term (n=16). Western blot analysis was performed to detect the protein expression levels of NLRP3, cleaved caspase-1, CBS and CSE in the placenta samples. Pearson's correlation analysis was performed to assess the correlation between NLRP3 inflammasome and H₂S synthetase. Human placental cells were cultured and treated with different concentrations of NaHS (0, 10, 25 and 50 nmol/l) or L-cysteine (0, 0.25, 0.50 and 1.00 mmol/l). In addition, western blot analysis was performed to detect the protein expression levels of NLRP3 and cleaved caspase-1, while ELISA was performed to measure the production of IL-1β and IL-18 in the culture media. The results demonstrated that the expression levels of NLRP3 and cleaved caspase-1 increased, while the expression levels of CBS and CSE decreased in the placenta samples. In addition, the expression levels of NLRP3 and cleaved caspase-1 were inversely correlated with the expression levels of CBS and CSE. Notably, NaHS and L-cysteine significantly suppressed the expression levels of NLRP3 and cleaved caspase-1, and the production of IL-1 and IL-18 in human placental cells. Taken together, the results of the present study suggest that H₂S synthetase deficiency in placenta may contribute to excessive activation of NLRP3 inflammasome in GDM.

Epigenetic Alterations Related to Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is the most common metabolic complication in pregnancy, which affects the future health of both the mother and the newborn. Its pathophysiology involves nutritional, hormonal, immunological, genetic and epigenetic factors. Among the latter, it has been observed that alterations in DNA (deoxyribonucleic acid) methylation patterns and in the levels of certain micro RNAs, whether in placenta or adipose tissue, are related to well-known characteristics of the disease, such as hyperglycemia, insulin resistance, inflammation and excessive placental growth. Furthermore, epigenetic alterations of gestational diabetes mellitus are observable in maternal blood, although their pathophysiological roles are completely unknown. Despite this, it has not been possible to determine the causes of the epigenetic characteristics of GDM, highlighting the need for integral and longitudinal studies. Based on this, this article summarizes the most relevant and recent studies on epigenetic alterations in placenta, adipose tissue and maternal blood associated with GDM in order to provide the reader with a general overview of the subject and indicate future research topics.

In severe obesity, subcutaneous adipose tissue cell-derived cytokines are early markers of impaired glucose tolerance and are modulated by quercetin

BACKGROUND

Excessive adiposity provides an inflammatory environment. However, in people with severe obesity, how systemic and local adipose tissue (AT)-derived cytokines contribute to worsening glucose tolerance is not clear.

METHODS

Ninty-two severely obese (SO) individuals undergoing bariatric surgery were enrolled and subjected to detailed clinical phenotyping. Following an oral glucose tolerance test, participants were included in three groups, based on the presence of normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or type 2 diabetes (T2D). Serum and subcutaneous AT (SAT) biopsies were obtained and mesenchymal stem cells (MSCs) were isolated, characterized, and differentiated in adipocytes in vitro. TNFA and PPARG mRNA levels were determined by qRT-PCR. Circulating, adipocyte- and MSC-released cytokines, chemokines, and growth factors were assessed by multiplex ELISA.

RESULTS

Serum levels of IL-9, IL-13, and MIP-1β were increased in SO individuals with T2D, as compared with those with either IGT or NGT. At variance, SAT samples obtained from SO individuals with IGT displayed levels of TNFA which were threefold higher compared to those with NGT, but not different from those with T2D. Elevated levels of TNFα were also found in differentiated adipocytes, isolated from the SAT specimens of individuals with IGT and T2D, compared to those with NGT. Consistent with the pro-inflammatory milieu, IL-1β and IP-10 secretion was significantly higher in adipocytes from individuals with IGT and T2D. Moreover, increased levels of TNFα, both mRNA and secreted protein were detected in MSCs obtained from IGT and T2D, compared to NGT SO individuals. Exposure of T2D and IGT-derived MSCs to the anti-inflammatory flavonoid quercetin reduced TNFα levels and was paralleled by a significant decrease of the secretion of inflammatory cytokines.

CONCLUSION

In severe obesity, enhanced SAT-derived inflammatory phenotype is an early step in the progression toward T2D and maybe, at least in part, attenuated by quercetin.

Protocatechuic acid influences immune-metabolic changes in the adipose tissue of pregnant women with gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with immune metabolic changes that increase women's risk of developing metabolic disorders later in life. Nutritional intervention is a crucial component in reducing the burden of these pathological features. We examined whether protocatechuic acid (PCA), a major metabolite of anthocyanins abundant in plant food, is able to exert insulin-mimetic activity and modulate inflammation in the visceral adipose tissue (VAT) obtained at delivery, from pregnant women with GDM or normal glucose tolerance (NGT). PCA stimulated glucose uptake in the VAT from both GDM and NGT women. This capability was associated with increased phosphorylation of p38 mitogen-activated protein kinase (p38MAPK), as further demonstrated by the inhibitory effect of SB203580, a p38MAPK inhibitor, on PCA-induced glucose uptake. The GDM-VAT expressed lower adiponectin levels and PCA stimulated adiponectin release in the NGT-VAT and, albeit to a lower extent, in the GDM-VAT. Higher levels of IL6 and TNFα were secreted by the GDM-VAT compared with the NGT one, and PCA had no effects on them. PCA reduced the overexpression of vasoactive intestinal peptide receptor 2 (VPAC2) in the GDM-VAT. Further studies are needed to establish whether and how anthocyanins and food rich in these compounds may contribute to prevent or delay metabolic disorders in women with GDM.

Molecular Mechanisms and Functions of lncRNAs in the Inflammatory Reaction of Diabetes Mellitus

Diabetes is a chronic inflammatory state, and several studies have shown that the mechanisms of insulin resistance and abnormal islet β-cell function in diabetes are closely related to inflammatory reactions. Inflammation plays a critical role in diabetic complications. Long noncoding RNAs (lncRNAs), a new area of genomic research for gene regulation, have complex biological functions in various aspects of cellular biological activity. Recent studies have shown that lncRNAs are associated with the regulation of inflammatory responses in various ways, including at the epigenetic, transcriptional, and posttranscriptional levels. This paper presents a brief review of studies on the mechanisms of lncRNAs in diabetic inflammation. The purpose of this article is to determine the role of lncRNAs in the process of diabetic inflammation and to provide new strategies for the use of lncRNAs in the treatments for diabetic inflammation.

Effects of miR-22-3p targeted regulation of Socs3 on the hepatic insulin resistance in mice with gestational diabetes mellitus

OBJECTIVE

Gestational diabetes mellitus (GDM) is one of the common complications of pregnant women, with serious threatening to pregnant women and newborns. The pathogenesis of GDM remains unclear now. This study aims to explore the effects of miR-22-3p targeted regulation of suppressors of cytokine signaling 3 (Socs3) on the hepatic insulin resistance (HIR) in mice with GDM.

METHODS

Healthy SPF C57BL/6J mice were selected to establish GDM model and divided into 7 groups: Normal group, Model group, NC-(negative control) mimic group, miR-22-3p mimic group, NC-pcDNA3.0 group, pcDNA3.0-Socs3 group, and miR-22-3p mimic + pcDNA3.0-Socs3 group. The islet morphology, and the expressions of miR-22-3p, Socs3 mRNA and Socs3 protein in the islet tissues were detected by HE staining, qRT-PCR and Western blot. Fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) were measured. Oral glucose tolerance test (OGTT) was performed to detect FBG and fasting insulin (FINS) contents, and insulin resistance (HOMA-IR) was calculated.

RESULTS

Compared with the Normal group, the model group had decreased levels of miR-22-3p and HDL-C, while increased levels of Socs3 mRNA and protein expressions, OGTT, FBG, FINS, and HOMA-IR, TG and TC (all P < 0.05). Compared with the Model group, the above indicators (OGTT, FBG, FINS, HOMA-IR, TG, TC and HDL-C) were improved in the miR-22-3p mimic group, but worsened in the pcDNA3.0-Socs3 group (all P < 0.05).

CONCLUSION

miR-22-3p can down-regulate the expression of Socs3, thereby inhibiting HIR in GDM mice.

Fetal and Placental Weight in Pre-Gestational Maternal Obesity (PGMO) vs. Excessive Gestational Weight Gain (EGWG)-A Preliminary Approach to the Perinatal Outcomes in Diet-Controlled Gestational Diabetes Mellitus

Both pre-gestational maternal obesity (PGMO) and excessive gestational weight gain (EGWG) increase the risk of gestational diabetes mellitus (GDM). Here, we conducted a retrospective study to comparatively examine the relation between fetal birth weight (FW) and placental weight (PW) in PGMO (n = 100) compared to EGWG (n = 100) with respect to perinatal outcomes in diet-controlled GDM. The control group was made up of 100 healthy pregnancies. The mean FW and the mean PW in EGWG were correlated with lowered fetal weight/placental weight ratio (FW/PW ratio). The percentage of births completed by cesarean section accounted for 47%, 32%, and 18% of all deliveries (EGWG, PGMO, and controls, respectively), with the predominance of FW-related indications for cesarean section. Extended postpartum hospital stays due to neonate were more frequent in EGWG, especially due to neonatal jaundice (p < 0.05). The results indicate the higher perinatal risk in mothers with EGWG compared to PGMO during GDM-complicated pregnancy. Further in-depth comparative studies involving larger patient pools are needed to validate these findings, the intent of which is to formulate guidelines for GDM patients in respect to management of PGMO and EGWG.

Altered SOCS3 DNA methylation within exon 2 is associated with increased mRNA expression in visceral adipose tissue in gestational diabetes

Overweight/obesity is the main risk factor for gestational diabetes mellitus (GDM). In our cohort of pregnant women with GDM, n = 19, and without, n = 22, we previously reported a significant increase in SOCS3 mRNA expression (+62%) in visceral adipose tissue (VAT) according to GDM, without altered promoter DNA-methylation. Here, we examined methylation status of additional SOCS3 exon 2 regions in VAT and maternal blood. We found significantly altered methylation at specific CpG sites corresponding to aberrant mRNA expression levels of SOCS3 in VAT. We propose a potential regulatory element/region within exon 2; however, this region does not appear to be a good blood-marker representing VAT.

Association of Single Nucleotide Polymorphisms of the IL-6, IL-10, and TNF-α Genes with Susceptibility to Gestational Diabetes Mellitus

Objective: To investigate any associations between the single nucleotide polymorphisms (SNPs) at the interleukin-6 (IL-6) rs1800796, interleukin-10 (IL-10) rs1800896, and the tumor necrosis factor-alpha (TNF-α) rs1800629 loci with gestational diabetes mellitus (GDM) susceptibility. Materials and Methods: A total of 242 GDM patients and 242 healthy controls were enrolled in this study. The genotypes of the IL-6 rs1800796, IL-10 rs1800896, and TNF-α rs1800629 loci were analyzed by Sanger sequencing. Interactions among these SNPs were analyzed through multifactor dimensionality reduction. Results: Women with the IL-6 rs1800796 G allele had a higher GDM susceptibility risk than those with the C allele (odds ratio [OR] = 1.44, 95% confidence interval [CI]: 1.10-1.90, p = 0.010). Women with the IL-10 rs1800896 C allele had a higher risk of GDM susceptibility than those with the T allele (OR = 2.94, 95% CI: 1.87-4.63, p < 0.001). Women with the TNF-α rs1800629 A allele had a higher risk of susceptibility to GDM than those with the G allele (OR = 3.73, 95% CI: 2.25-6.18, p < 0.001). The plasma levels of IL-6 and TNF-α in GDM patients were significantly higher than those in the control group, and the levels of IL-10 were significantly lower than those in the control group (p < 0.001). Women with the IL-6 rs1800796 CG/GG genotypes had higher plasma IL-6 levels than those with the CC genotype (p < 0.05). Women with the IL-10 rs1800896 TT genotype had higher IL-10 levels than those with the TC/CC genotypes (p < 0.05), and those with the TNF-α rs1800629 GA/AA genotypes had higher TNF-α levels than those with the GG genotype (p < 0.05). Conclusion: The results of this study show that the IL-6 rs1800796 G allele, the IL-10 rs1800896 C allele, and the TNF-α rs1800629 A allele are significantly associated with an increased risk of susceptibility to GDM.