The Role of Phosphatidylethanolamine N-Methyltransferase (PEMT) and Its Waist-Hip-Ratio-Associated Locus rs4646404 in Obesity-Related Metabolic Traits and Liver Disease.

In previous genome-wide association studies (GWAS), genetic loci associated with obesity and impaired fat distribution (FD) have been identified. In the present study, we elucidated the role of the PEMT gene, including the waist-hip-ratio-associated single nucleotide polymorphism rs4646404, and its influence on obesity-related metabolic traits. DNA from 2926 metabolically well-characterized subjects was used for genotyping. PEMT expression was analyzed in paired visceral (vis) and subcutaneous (sc) adipose tissue (AT) from a subset of 574 individuals. Additionally, PEMT expression was examined in vis, sc AT and liver tissue in a separate cohort of 64 patients with morbid obesity and liver disease. An in vitro Pemt knockdown was conducted in murine epididymal and inguinal adipocytes. Our findings highlight tissue-specific variations in PEMT mRNA expression across the three studied tissues. Specifically, vis PEMT mRNA levels correlated significantly with T2D and were implicated in the progression of non-alcoholic steatohepatitis (NASH), in contrast to liver tissue, where no significant associations were found. Moreover, sc PEMT expression showed significant correlations with several anthropometric- and metabolic-related parameters. The rs4646404 was associated with vis AT PEMT expression and also with diabetes-related traits. Our in vitro experiments supported the influence of PEMT on adipogenesis, emphasizing its role in AT biology. In summary, our data suggest that PEMT plays a role in regulating FD and has implications in metabolic diseases.

Obesity and COVID-19: What are the Consequences?

Obesity is an increasing health problem all over the world. In combination with the current COVID-19 pandemic, this has turned into a massive challenge as individuals with overweight and obesity at all ages show a significant increase in their risk of getting severe COVID-19. Around 20% of all patients that were hospitalized for COVID-19 suffered from obesity alone, whereas obesity in combination with other metabolic comorbidities, such as type 2 diabetes and hypertension, account for up to 60% of all hospitalizations in relation to COVID-19. Therefore, it is of immense importance to put the spotlight on the high incidence of obesity present already in childhood both by changing the individual minds and by encouraging politicians and the whole society to commence preventive interventions for achieving a better nutrition for all social classes all over the world. In the current review, we aim to explain the different pathways and mechanisms that are responsible for the increased risk of severe COVID-19 in people with overweight and obesity. Furthermore, we discuss how the pandemic has led to weight gains in many people during lockdown. At the end, we discuss the importance of preventing such an interface between a non-communicable disease like obesity and a communicable disease like COVID-19 in the future.

Adipsin Serum Concentrations and Adipose Tissue Expression in People with Obesity and Type 2 Diabetes.

(1) Adipsin is an adipokine that may link increased fat mass and adipose tissue dysfunction to obesity-related cardiometabolic diseases. Here, we investigated whether adipsin serum concentrations and adipose tissue (AT) adipsin mRNA expression are related to parameters of AT function, obesity and type 2 diabetes (T2D). (2) Methods: A cohort of 637 individuals with a wide range of age and body weight (Age: 18-85 years; BMI: 19-70 kg/m2) with (n = 237) or without (n = 400) T2D was analyzed for serum adipsin concentrations by ELISA and visceral (VAT) and subcutaneous (SAT) adipsin mRNA expression by RT-PCR. (3) Results: Adipsin serum concentrations were significantly higher in patients with T2D compared to normoglycemic individuals. We found significant positive univariate relationships of adipsin serum concentrations with age (r = 0.282, p < 0.001), body weight (r = 0.264, p < 0.001), fasting plasma glucose (r = 0.136, p = 0.006) and leptin serum concentrations (r = 0.362, p < 0.001). Neither VAT nor SAT adipsin mRNA expression correlated with adipsin serum concentrations after adjusting for age, sex and BMI. Independent of T2D status, we found significantly higher adipsin expression in SAT compared to VAT (4) Conclusions: Our data suggest that adipsin serum concentrations are strongly related to obesity and age. However, neither circulating adipsin nor adipsin AT expression reflects parameters of impaired glucose or lipid metabolism in patients with obesity with or without T2D.

Metabolic Effects of the Waist-To-Hip Ratio Associated Locus GRB14/COBLL1 Are Related to GRB14 Expression in Adipose Tissue.

GRB14/COBLL1 locus has been shown to be associated with body fat distribution (FD), but neither the causal gene nor its role in metabolic diseases has been elucidated. We hypothesize that GRB14/COBLL1 may act as the causal genes for FD-related SNPs (rs10195252 and rs6738627), and that they may be regulated by SNP to effect obesity-related metabolic traits. We genotyped rs10195252 and rs6738627 in 2860 subjects with metabolic phenotypes. In a subgroup of 560 subjects, we analyzed GRB14/COBLL1 gene expression in paired visceral and subcutaneous adipose tissue (AT) samples. Mediation analyses were used to determine the causal relationship between SNPs, AT GRB14/COBLL1 mRNA expression, and obesity-related traits. In vitro gene knockdown of Grb14/Cobll1 was used to test their role in adipogenesis. Both gene expressions in AT are correlated with waist circumference. Visceral GRB14 mRNA expression is associated with FPG and HbA1c. Both SNPs are associated with triglycerides, FPG, and leptin levels. Rs10195252 is associated with HbA1c and seems to be mediated by visceral AT GRB14 mRNA expression. Our data support the role of the GRB14/COBLL1 gene expression in body FD and its locus in metabolic sequelae: in particular, lipid metabolism and glucose homeostasis, which is likely mediated by AT GRB14 transcript levels.

DNA methylation of SSPN is linked to adipose tissue distribution and glucose metabolism.

DNA methylation is a crucial epigenetic mechanism in obesity and fat distribution. We explored the Sarcospan ( SSPN) gene locus by using genome-wide data sets comprising methylation and expression data, pyrosequencing analysis in the promoter region, and genetic analysis of an SNP variant rs718314, which was previously reported to associate with waist-to-hip ratio. We found that DNA methylation influences several clinical variables related to fat distribution and glucose metabolism, while SSPN mRNA levels showed directionally opposite effects on these traits. Complete DNA methylation of the SSPN promoter construct suppressed the gene expression of firefly luciferase in MCF7 cells. Moreover, rs718314 was associated with waist and with DNA methylation at CpG sites. Our data strongly support the role of the SSPN locus in body fat composition and glucose homeostasis, and suggest that this is most likely the result of changes in DNA methylation of SSPN in adipose tissue.-Keller, M., Klös, M., Rohde, K., Krüger, J., Kurze, T., Dietrich, A., Schön, M. R., Gärtner, D., Lohmann, T., Dreßler, M., Stumvoll, M., Blüher, M., Kovacs, P., Böttcher, Y. DNA methylation of SSPN is linked to adipose tissue distribution and glucose metabolism.

Measuring Biological Age via Metabonomics: The Metabolic Age Score.

Chronological age is one of the most important risk factors for adverse clinical outcome. Still, two individuals at the same chronological age could have different biological aging states, leading to different individual risk profiles. Capturing this individual variance could constitute an even more powerful predictor enhancing prediction in age-related morbidity. Applying a nonlinear regression technique, we constructed a metabonomic measurement for biological age, the metabolic age score, based on urine data measured via (1)H NMR spectroscopy. We validated the score in two large independent population-based samples by revealing its significant associations with chronological age and age-related clinical phenotypes as well as its independent predictive value for survival over approximately 13 years of follow-up. Furthermore, the metabolic age score was prognostic for weight loss in a sample of individuals who underwent bariatric surgery. We conclude that the metabolic age score is an informative measurement of biological age with possible applications in personalized medicine.

Telomere length differences between subcutaneous and visceral adipose tissue in humans.

Adipocyte hypertrophy and hyperplasia have been shown to be associated with shorter telomere length, which may reflect aging, altered cell proliferation and adipose tissue (AT) dysfunction. In individuals with obesity, differences in fat distribution and AT cellular composition may contribute to obesity related metabolic diseases. Here, we tested the hypotheses that telomere lengths (TL) are different between: (1) abdominal subcutaneous and omental fat depots, (2) superficial and deep abdominal subcutaneous AT (SAT), and (3) adipocytes and cells of the stromal vascular fraction (SVF). We further asked whether AT TL is related to age, anthropometric and metabolic traits. TL was analyzed by quantitative PCR in total human genomic DNA isolated from paired subcutaneous and visceral AT of 47 lean and 50 obese individuals. In subgroups, we analyzed TL in isolated small and large adipocytes and SVF cells. We find significantly shorter TL in subcutaneous compared to visceral AT (P < 0.001) which is consistent in men and subgroups of lean and obese, and individuals with or without type 2 diabetes (T2D). Shorter TL in SAT is entirely due to shorter TL in the SVF compared to visceral AT (P < 0.01). SAT TL is most strongly correlated with age (r = -0.205, P < 0.05) and independently of age with HbA1c (r = -0.5, P < 0.05). We found significant TL differences between superficial SAT of lean and obese as well as between individuals with our without T2D, but not between the two layers of SAT. Our data indicate that fat depot differences in TL mainly reflect shorter TL of SVF cells. In addition, we found an age and BMI-independent relationship between shorter TL and HbA1c suggesting that chronic hyperglycemia may impair the regenerative capacity of AT more strongly than obesity alone.

Global DNA methylation levels in human adipose tissue are related to fat distribution and glucose homeostasis.

AIMS/HYPOTHESIS: Epigenetic alterations may influence the metabolic pathways involved in human obesity. We hypothesised that global DNA methylation levels in adipose tissue might be associated with obesity and related phenotypes. METHODS: We measured global DNA methylation levels in paired samples of subcutaneous adipose tissue (SAT) and omental visceral adipose tissue (OVAT) from 51 individuals, and in leucocytes from 559 Sorbs, a population from Germany, using LUminometric Methylation Assay (LUMA). To further investigate the underlying mechanisms of the observed associations, we measured global methylation levels in 3T3-L1 adipocytes exposed to glucose, insulin and lipids. RESULTS: Global methylation levels (±SD) were significantly higher in OVAT (74.27% ± 2.2%) compared with SAT (71.97% ± 2.4%; paired t test, p < 1 × 10(-9)). Furthermore, global methylation levels in SAT were positive correlates of measures of fat distribution (waist measurement, WHR) and glucose homeostasis (HbA1c) (all p < 0.015 after accounting for multiple testing and covariates). Global methylation levels in the German Sorb cohort were associated with glucose homeostasis, but this association did not withstand adjustment for covariates. Exposure of 3T3-L1 adipocytes to insulin, palmitate and glucose decreased global methylation levels 1 h after treatment relative to controls. CONCLUSIONS/INTERPRETATION: Our data suggest that the variability in global methylation in adipose tissue might be related to alterations in glucose metabolism.

Sex-Specific Effects of the Genetic Variant rs10487505 Upstream of leptin in the Development of Obesity.

The SNP rs10487505 in the promotor region of the leptin gene was reported to be associated with decreased circulating leptin and increased body mass index (BMI). However, the phenotypic outcomes affected by rs10487505 in the leptin regulatory pathway have not been systematically studied. Therefore, the aim of this study was to elucidate the influence of rs10487505 on leptin mRNA expression and obesity-related parameters. We genotyped rs10487505 in DNA samples from 1665 patients with obesity and lean controls and measured leptin gene expression in paired samples of adipose tissue (AT, N = 310), as well as circulating leptin levels. We confirm the leptin-lowering effect of rs10487505 in women. In contrast to the previously reported data from population-based studies, in this mainly obese cohort, we describe a lower mean BMI in women carrying the C allele of rs10487505. However, no association of rs10487505 with AT leptin mRNA expression was found. Our data suggest that reduced circulating leptin levels are not a result of the direct silencing of leptin mRNA expression. Furthermore, leptin reduction by rs10487505 does not associate with BMI in a linear manner. Instead, the decreasing effect on BMI might be dependent on the severity of obesity.

Defective suppressor function of human CD4+ CD25+ regulatory T cells in autoimmune polyglandular syndrome type II.

In autoimmune polyglandular syndromes (APS), several organ-specific autoimmune diseases are clustered. Although APS type I is caused by loss of central tolerance, the etiology of APS type II (APS-II) is currently unknown. However, in several murine models, depletion of CD4(+) CD25(+) regulatory T cells (T(regs)) causes a syndrome resembling human APS-II with multiple endocrinopathies. Therefore, we hypothesized that loss of active suppression in the periphery could be a hallmark of this syndrome. T(regs) from peripheral blood of APS-II, control patients with single autoimmune endocrinopathies, and normal healthy donors showed no differences in quantity (except for patients with isolated autoimmune diseases), in functionally important surface markers, or in apoptosis induced by growth factor withdrawal. Strikingly, APS-II T(regs) were defective in their suppressive capacity. The defect was persistent and not due to responder cell resistance. These data provide novel insights into the pathogenesis of APS-II and possibly human autoimmunity in general.

Effects of Weight Loss on Glutathione Peroxidase 3 Serum Concentrations and Adipose Tissue Expression in Human Obesity.

BACKGROUND/AIMS: Altered expression and circulating levels of glutathione peroxidase 3 (GPX3) have been observed in obesity and type 2 diabetes (T2D) across species. Here, we investigate whether GPX3 serum concentrations and adipose tissue (AT) GPX3 mRNA expression are related to obesity and weight loss. METHODS: GPX3 serum concentration was measured in 630 individuals, including a subgroup (n = 293) for which omental and subcutaneous (SC) GPX3 mRNA expression has been analyzed. GPX3 analyses include three interventions: 6 months after bariatric surgery (n = 80) or combined exercise/hypocaloric diet (n = 20) or two-step bariatric surgery (n = 24) studies. RESULTS: Bariatric surgery-induced weight loss (-25.8 ± 8.4%), but not a moderate weight reduction of -8.8 ± 6.5% was associated with significantly reduced GPX3 serum concentrations. GPX3 mRNA is significantly higher expressed in AT from individuals with normal glucose metabolism compared to T2D patients. SC AT GPX3 expression is significantly higher in lean compared to obese as well as in insulin-sensitive compared insulin-resistant individuals with obesity. Weight loss after bariatric surgery causes a significant increase in SC AT GPX3 expression. AT GPX3 expression significantly correlates with age, BMI, fat distribution, insulin sensitivity (only SC AT), but not with circulating GPX3. CONCLUSION: Our data support the notion that SC AT GPX3 expression is associated with obesity, fat distribution and related to whole body insulin resistance.

IRS1 DNA promoter methylation and expression in human adipose tissue are related to fat distribution and metabolic traits.

The SNP variant rs2943650 near IRS1 gene locus was previously associated with decreased body fat and IRS1 gene expression as well as an adverse metabolic profile in humans. Here, we hypothesize that these effects may be mediated by an interplay with epigenetic alterations. We measured IRS1 promoter DNA methylation and mRNA expression in paired human subcutaneous and omental visceral adipose tissue samples (SAT and OVAT) from 146 and 41 individuals, respectively. Genotyping of rs2943650 was performed in all individuals (N = 146). We observed a significantly higher IRS1 promoter DNA methylation in OVAT compared to SAT (N = 146, P = 8.0 × 10-6), while expression levels show the opposite effect direction (N = 41, P = 0.011). OVAT and SAT methylation correlated negatively with IRS1 gene expression in obese subjects (N = 16, P = 0.007 and P = 0.010). The major T-allele is related to increased DNA methylation in OVAT (N = 146, P = 0.019). Finally, DNA methylation and gene expression in OVAT correlated with anthropometric traits (waist- circumference waist-to-hip ratio) and parameters of glucose metabolism in obese individuals. Our data suggest that the association between rs2943650 near the IRS1 gene locus with clinically relevant variables may at least be modulated by changes in DNA methylation that translates into altered IRS1 gene expression.

Genome-wide DNA promoter methylation and transcriptome analysis in human adipose tissue unravels novel candidate genes for obesity.

OBJECTIVE/METHODS: DNA methylation plays an important role in obesity and related metabolic complications. We examined genome-wide DNA promoter methylation along with mRNA profiles in paired samples of human subcutaneous adipose tissue (SAT) and omental visceral adipose tissue (OVAT) from non-obese vs. obese individuals. RESULTS: We identified negatively correlated methylation and expression of several obesity-associated genes in our discovery dataset and in silico replicated ETV6 in two independent cohorts. Further, we identified six adipose tissue depot-specific genes (HAND2, HOXC6, PPARG, SORBS2, CD36, and CLDN1). The effects were further supported in additional independent cohorts. Our top hits might play a role in adipogenesis and differentiation, obesity, lipid metabolism, and adipose tissue expandability. Finally, we show that in vitro methylation of SORBS2 directly represses gene expression. CONCLUSIONS: Taken together, our data show distinct tissue specific epigenetic alterations which associate with obesity.

Efficacy and tolerability of pegylated IFN-alpha in patients with neuroendocrine gastroenteropancreatic carcinomas.

Interferon-alpha (IFN-alpha) is well established in the treatment of neuroendocrine carcinomas (NEC). Treatment is accompanied by fatigue and flu-like symptoms. In patients with chronic hepatitis C, pegylated IFN (PEGIFN) leads to improved antiviral efficacy and good tolerability. Our aim was to assess the efficacy and tolerability of PEG-IFN on the management of patients with well-differentiated NEC of the gastroenteropancreatic system. In 17 patients, the effect of PEG-IFN-alpha2b was studied. After first-line octreotide treatment, IFN-alpha was added at the time of tumor progression. Six patients were switched from conventional IFN-alpha, and 11 patients were IFN naive. Inhibition of tumor growth, including stabilization of disease, occurred in 13 of 17 patients, and biochemical and symptomatic responses were seen in 7 of 10 patients with functionally active tumors. Tolerability of PEG-IFN-alpha2b was much better than that of IFN-alpha. Fatigue occurred in 59% of all patients but was mild in severity. Eleven of thirteen patients who had a benefit remained on therapy for a median time of 20 months (range 6-30 months). PEG-IFN-alpha2b provides symptomatic and antiproliferative efficacy in patients with NEC. Better tolerability of PEG-IFN-alpha2b improved patients' compliance, justifying its use in patients who do not tolerate conventional IFN-alpha treatment.

Enhanced platelet activation by prolactin in patients with ischemic stroke.

Prolactin and leptin are newly recognised platelet co-stimulators due to potentiation of ADP-induced platelet aggregation. Elevated leptin levels have recently been found to be a risk factor for ischemic stroke in both men and women, and especially in combination with increased blood pressure for hemorrhagic stroke in men. Until now an association between hyperprolactinemia and ischemic stroke has not been investigated systematically. We determined plasma prolactin and leptin levels as well as platelet P-selectin expression in 36 patients with ischemic stroke or transient ischemic attack and detected a significant correlation between increased prolactin values and enhanced ADP stimulated P-selectin expression on platelets. In contrast, no correlation of leptin values with platelet P-selectin expression was found. Next we determined plasma prolactin and leptin as well as acquired and congenital risk factors of thrombophilia in patients with first-ever non-hemorrhagic stroke with or without atrial fibrillation. Excluding patients with such preexisting risk factors, 21 patients with and 59 patients without atrial fibrillation were identified. Patients without atrial fibrillation revealed significantly higher plasma prolactin levels than patients with atrial fibrillation. Furthermore, the influence of aspirin or clopidogrel on prolactin stimulated P-selectin expression in vitro was tested, showing that aspirin was without effect, whereas clopidogrel significantly inhibited platelet P-selectin expression. In conclusion, hyperprolactinemia might be a novel risk factor for stroke mediating its thrombogenic effect through enhanced platelet reactivity, and this might correspond to a higher efficacy of antiplatelet combination therapy with clopidogrel compared to aspirin therapy alone.

Fat depot-specific expression of HOXC9 and HOXC10 may contribute to adverse fat distribution and related metabolic traits.

OBJECTIVE: Independent previous studies in both rodents and humans suggest a role of developmental genes in the origin of obesity and body fat distribution. Here, the hypothesis that human adipose tissue (AT) expression of the developmental genes homeobox transcription factors C9 (HOXC9) and C10 (HOXC10) is fat depot-specific and related to obesity-related traits was tested. METHODS: In 636 individuals, HOXC9 and HOXC10 mRNA expression was investigated in paired abdominal subcutaneous (SC) and omental AT samples in relation to a wide range of age, BMI, fat distribution, and metabolic parameters and in subfractions of isolated adipocytes and cells of the stromal vascular fraction (SVF). RESULTS: HOXC9 and HOXC10 mRNA expression is significantly higher in SC compared to omental AT. HOXC9 and HOXC10 mRNA expression significantly correlates with body fat mass, even after adjustment for age and gender. In smaller subgroups (depending on the availability of data), fat depot-related significant gender- and BMI-independent associations between HOXC9 and HOXC10 gene expression and parameters of glucose metabolism and AT biology were found (e.g., adipocyte size). CONCLUSIONS: Taken together, these data suggest that HOXC9 and HOXC10 may play an important role in the development of obesity, adverse fat distribution, and subsequent alterations in whole-body metabolism and AT function.

Hypoxia-inducible factor 3A gene expression and methylation in adipose tissue is related to adipose tissue dysfunction.

Recently, a genome-wide analysis identified DNA methylation of the HIF3A (hypoxia-inducible factor 3A) as strongest correlate of BMI. Here we tested the hypothesis that HIF3A mRNA expression and CpG-sites methylation in adipose tissue (AT) and genetic variants in HIF3A are related to parameters of AT distribution and function. In paired samples of subcutaneous AT (SAT) and visceral AT (VAT) from 603 individuals, we measured HIF3A mRNA expression and analyzed its correlation with obesity and related traits. In subgroups of individuals, we investigated the effects on HIF3A genetic variants on its AT expression (N = 603) and methylation of CpG-sites (N = 87). HIF3A expression was significantly higher in SAT compared to VAT and correlated with obesity and parameters of AT dysfunction (including CRP and leucocytes count). HIF3A methylation at cg22891070 was significantly higher in VAT compared to SAT and correlated with BMI, abdominal SAT and VAT area. Rs8102595 showed a nominal significant association with AT HIF3A methylation levels as well as with obesity and fat distribution. HIF3A expression and methylation in AT are fat depot specific, related to obesity and AT dysfunction. Our data support the hypothesis that HIF pathways may play an important role in the development of AT dysfunction in obesity.

ADCY5 gene expression in adipose tissue is related to obesity in men and mice.

Genome wide association studies revealed an association of the single nucleotide polymorphism rs11708067 within the ADCY5 gene--encoding adenylate cyclase 5--with increased type 2 diabetes (T2D) risk and higher fasting glucose. However, it remains unclear whether the association between ADCY5 variants and glycemic traits may involve adipose tissue (AT) related mechanisms. We therefore tested the hypothesis that ADCY5 mRNA expression in human and mouse AT is related to obesity, fat distribution, T2D in humans and high fat diet (HFD) in mice. We measured ADCY5 mRNA expression in paired samples of visceral and subcutaneous adipose tissue from 244 individuals with a wide range of body weight and parameters of hyperglycemia, which have been genotyped for rs11708067. In addition, AT ADCY5 mRNA was assessed in C57BL/6NTac which underwent a 10 weeks standard chow (n = 6) or high fat diet (HFD, n = 6). In humans, visceral ADCY5 expression is significantly higher in obese compared to lean individuals. ADCY5 expression correlates with BMI, body fat mass, circulating leptin, fat distribution, waist and hip circumference, but not with fasting plasma glucose and HbA1c. Adcy5 expression in mouse AT is significantly higher after a HFD compared to chow (p<0.05). Importantly, rs11708067 is not associated with ADCY5 mRNA expression levels in either fat depot in any of the genetic models tested. Our results suggest that changes in AT ADCY5 expression are related to obesity and fat distribution, but not with impaired glucose metabolism and T2D. However, altered ADCY5 expression in AT does not seem to be the mechanism underlying the association between rs11708067 and increased T2D risk.