Independent and opposite associations of serum levels of omentin-1 and adiponectin with increases of glycaemia and incident type 2 diabetes in an older population: KORA F4/FF4 study

Omentin Increases Glucose Uptake, but Not Insulin Sensitivity in Human Myotubes Dependent on Extracellular Lactotransferrin

INTRODUCTION

Omentin (intelectin-1) is an adipokine produced by the stromal vascular fraction of visceral adipose tissue and has been positively associated with insulin sensitivity. The underlying mechanism of action, however, is largely unknown. It has been described that omentin may increase insulin sensitivity and glucose uptake of adipocytes, but effects on other insulin-sensitive tissues such as skeletal muscle are unexplored. We therefore investigated effects of omentin on insulin sensitivity and metabolism of primary human myotubes.

METHODS

Primary human myotubes were treated with 0.5 or 2 µg/mL omentin and subsequently protein detection, glucose uptake assay, lactate assay, and lipidomics analysis were performed.

RESULTS

Omentin did not affect skeletal muscle insulin signaling, as assessed by basal and insulin-stimulated phosphorylation of IRS1 and AKT. Omentin increased basal, but not insulin-stimulated glucose uptake. While increased glycolytic activity was confirmed by elevated lactate release after omentin treatment, effects on cellular lipid composition were limited to an increase in total triacylglycerol concentration. Increased glucose uptake by omentin was counteracted by addition of extracellular lactotransferrin, which can bind to omentin.

CONCLUSIONS

Overall, increased basal glucose uptake in skeletal muscle cells suggests differential effects of omentin on insulin-sensitive tissues. Moreover, an involvement of lactotransferrin in omentin's mechanism of action may partially explain contradictory results of epidemiological studies on the role of omentin in different diseases.

Omentin associates with serum metabolite profiles indicating lower diabetes risk: KORA F4 Study

INTRODUCTION

Circulating omentin levels have been positively associated with insulin sensitivity. Although a role for adiponectin in this relationship has been suggested, underlying mechanisms remain elusive. In order to reveal the relationship between omentin and systemic metabolism, this study aimed to investigate associations of serum concentrations of omentin and metabolites.

RESEARCH DESIGN AND METHODS

This study is based on 1124 participants aged 61-82 years from the population-based KORA (Cooperative Health Research in the Region of Augsburg) F4 Study, for whom both serum omentin levels and metabolite concentration profiles were available. Associations were assessed with five multivariable regression models, which were stepwise adjusted for multiple potential confounders, including age, sex, body mass index, waist-to-hip ratio, lifestyle markers (physical activity, smoking behavior and alcohol consumption), serum adiponectin levels, high-density lipoprotein cholesterol, use of lipid-lowering or anti-inflammatory medication, history of myocardial infarction and stroke, homeostasis model assessment 2 of insulin resistance, diabetes status, and use of oral glucose-lowering medication and insulin.

RESULTS

Omentin levels significantly associated with multiple metabolites including amino acids, acylcarnitines, and lipids (eg, sphingomyelins and phosphatidylcholines (PCs)). Positive associations for several PCs, such as diacyl (PC aa C32:1) and alkyl-alkyl (PC ae C32:2), were significant in models 1-4, whereas those with hydroxytetradecenoylcarnitine (C14:1-OH) were significant in all five models. Omentin concentrations were negatively associated with several metabolite ratios, such as the valine-to-PC ae C32:2 and the serine-to-PC ae C32:2 ratios in most models.

CONCLUSIONS

Our results suggest that omentin may influence insulin sensitivity and diabetes risk by changing systemic lipid metabolism, but further mechanistic studies investigating effects of omentin on metabolism of insulin-sensitive tissues are needed.

Evaluation of serum adipokines (omentin-1 and visfatin) in coronary artery disease at a North Indian hospital

Objective. Adipose tissue is considered to be an endocrine organ that secretes bioactive substances known as adipokines that contribute to the pathophysiology of metabolic and coronary diseases related to obesity. In this study, various novel biomarkers, such as inflammatory markers that are pro-inflammatory (visfatin) and anti-inflammatory (omentin-1), as prognostic indicators for people with coronary artery disease (CAD) were investigated. Methods. In this study, 30 diabetic patients with CAD, 30 diabetic patients without CAD, and 30 healthy control counterparts were included. Serum omentin and visfatin concentrations were evaluated by solid-phase enzyme linked immunosorbent assay (ELISA) kit. Patients with established diagnosis of CAD based on angiography, ECG, and elevated cardiac marker level were included into the study. Patients with cardioembolic stroke, cerebral venous sinus thrombosis, CNS vasculitis, and hemorrhage due to trauma, tumor, vascular malformation, and coagulopathy were excluded. Results. The serum omentin-1 levels were significantly higher in the healthy controls in comparison with the diabetic group (p<0.0001) and serum visfatin levels were significantly higher in the diabetic group in comparison with the healthy controls (p<0.0001). The serum omentin levels were significantly higher in the diabetic group in comparison with the cardio-diabetic group (p<0.0001) and serum visfatin levels were significantly higher in the cardio-diabetic group in comparison with the diabetic group (p<0.0001). The serum omentin-1 showed negative correlation with the serum visfatin in the cardio-diabetic group. Conclusion. The adipokines, such as omentin and visfatin, may be good therapeutic candidates in preventing or ameliorating CAD.

Effect of obesity on the associations of 25-hydroxyvitamin D with prevalent and incident distal sensorimotor polyneuropathy: population-based KORA F4/FF4 study

Background/objectives

The association between vitamin D and DSPN has been investigated in cross-sectional studies in individuals with diabetes. However, evidence from prospective and population-based studies is still lacking. Also, the potential modifying effect of obesity and glucose tolerance has not been investigated. Therefore, we examined the cross-sectional and prospective associations of serum 25(OH)D with DSPN and assessed possible effect modifications.

Subjects/methods

The study included individuals aged 62–81 years who participated in the German KORA F4 (2006–2008) and FF4 (2013–2014) studies. DSPN was assessed using the Michigan Neuropathy Screening Instrument. Cross-sectional analyses (n = 1065; 33% of the participants had obesity) assessed the associations of baseline 25(OH)D with prevalent DSPN, while prospective analyses (n = 422) assessed the associations of 25(OH)D with incident DSPN.

Results

No association was found between 25(OH)D and prevalent DSPN in the total sample after adjustment for age, sex, season of blood sampling, BMI, metabolic variables, lifestyle factors, and comorbidities. However, a decrease by 10 nmol/L in 25(OH)D was associated with prevalent DSPN (RR (95% CI) 1.08 (1.01, 1.16)) in individuals with obesity but not in normal-weight individuals (RR (95% CI) 0.97 (0.92, 1.02), p_interaction = 0.002). No evidence for effect modification by glucose tolerance was found (p > 0.05). In the prospective analysis, 25(OH)D levels in the first and second tertiles were associated with higher risk of DSPN (RR (95% CI) 1.18 (1.02; 1.38) and 1.40 (1.04; 1.90)) compared to the third tertile after adjustment for age, sex, season of blood sampling, and BMI. There was no evidence for effect modification by obesity or glucose tolerance categories.

Conclusions

Our study did not show consistent evidence for cross-sectional and prospective associations between serum 25(OH)D levels and DSPN in the total study population of older individuals. However, there was evidence for an association between lower serum 25(OH)D levels and higher prevalence of DSPN in individuals with obesity.

Omentin-1: A newly discovered warrior against metabolic related diseases

INTRODUCTION

: Chronic metabolism-related diseases are challenging clinical problems. Omentin-1 is mainly expressed in stromal vascular cells of adipose tissue and can also be expressed in airway goblet cells, mesothelial cells, and vascular cells. Omentin-1 has been found to exert important anti-inflammatory, antioxidative and anti-apoptotic roles and to regulate endothelial dysfunction. Moreover, omentin-1 also has protective effects against cancer, atherosclerosis, type 2 diabetes mellitus, and bone metabolic diseases. The current review will discuss the therapeutic potential of omentin-1.

AREAS COVERED

: This review summarizes the biological actions of omentin-1 and provides an overview of omentin-1 in metabolic-related diseases. The relevant literature was derived from a PubMed search spanning 1998-2021 using these search terms: omentin-1, atherosclerosis, diabetes mellitus, bone, cancer, inflammation, and oxidative stress.

EXPERT OPINION

: As a novel adipocytokine, omentin-1 is a promising therapeutic target in metabolic-related diseases. Preclinical animal studies have shown encouraging results. Moreover, circulating omentin-1 has excellent potential as a noninvasive biomarker. In the future, strategies for regulating omentin-1 need to be investigated further in clinical trials in a large cohort.

Association of circulating MR-proADM with all-cause and cardiovascular mortality in the general population: Results from the KORA F4 cohort study

Background and aim

Despite its vasodilatory effect, adrenomedullin and its surrogate mid-regional pro-adrenomedullin (MR-proADM) have been found to be positively associated with all-cause and cardiovascular mortality. However, the underlying mechanisms thereof remain unclear and the associations were mostly shown in geriatric cohorts or in patients with chronic diseases. Therefore, we aimed to investigate the possible involvement of abdominal obesity, selected adipokines, and biomarkers of subclinical inflammation in the association of MR-proADM with mortality in a population based study cohort.

Methods

Prospective analysis of the KORA F4 study; median follow-up 9.1 (8.8–9.4) years. Complete data on MR-proADM and mortality was available for 1551 participants, aged 56.9±12.9 years (mean±SD). Correlation and regression analyses of MR-proADM with overall (BMI) and abdominal obesity (waist circumference), selected adipokines and biomarkers of subclinical inflammation. Cox proportional hazard models on the association of MR-proADM with all-cause and cardiovascular mortality with adjustment for cardiovascular risk factors and selected biomarkers in study subgroups (n = 603–1551).

Results

MR-proADM associated with all-cause (HR (95%CI): 2.37 (1.72–3.26) and 2.31 (1.67–3.20)) and cardiovascular mortality (4.28 (2.19–8.39) and 4.44 (2.25–8.76)) after adjustment for traditional cardiovascular risk factors including BMI or waist circumference, respectively. MR-proADM was further associated with four out of seven examined adipokines (leptin, retinol-binding protein-4, chemerin, and adiponectin) and with five out of eleven examined biomarkers of subclinical inflammation (high-sensitivity C-reactive protein, interleukin-6, myeloperoxidase, interleukin-22, and interleukin-1 receptor antagonist) after multivariable adjustment and correction for multiple testing. However, only IL-6 substantially attenuated the association of MR-proADM with all-cause mortality.

Conclusions

We found an association of MR-proADM with (abdominal) obesity, selected adipokines, and biomarkers of subclinical inflammation. However, the association of MR-proADM with mortality was independent of these parameters. Future studies should investigate the role of IL-6 and further characteristics of subclinical inflammation in the association between MR-proADM and all-cause mortality.

Omentin as an Independent Predictor of Metabolic Syndrome and Obesity Among Adolescents in Northeast China

PURPOSE

We investigated the association of omentin with metabolic syndrome (MetS), MetS components, and obesity in adolescents.

METHODS

A total of 742 middle-school students from Liaoyang City were enrolled in this cross-sectional study using the stratified cluster sampling method. Clinical information and blood samples were collected, and serum omentin levels were measured using enzyme-linked immunosorbent assay.

RESULTS

Mean plasma omentin levels were lower in male than in female participants (88.25 (interquartile range 63.02-133.61) vs 99.46 (interquartile range 69.08-188.35) ng/L, P = 0.004). The participants were divided into four groups according to the quartile (Q) values of omentin from low to high. With increasing omentin levels from Q1 to Q4, the age of adolescents and the proportion of males gradually increased (P < 0.05), whereas the body mass index (BMI) (P < 0.05) and prevalence of MetS (P > 0.05) tended to decrease. Omentin levels were significantly and negatively correlated with waist circumference and BMI (correlation coefficients of -0.099 and -0.115, respectively). Regression analysis showed that omentin level was independently associated with the risk of MetS (Odds ratio, OR = 0.639, 95% confidence interval, CI (0.432, 0.945)), which was attributed to the association with central obesity (OR = 0.775, 95% CI (0.605, 0.993)) among MetS components. Increased omentin levels also indicated a reduced risk of obesity (OR = 0.700, 95% CI (0.563, 0.870)).

CONCLUSION

Omentin is an independent predictor of MetS and obesity among adolescents in northeast China.

Association of renin and aldosterone with glucose metabolism in a Western European population: the KORA F4/FF4 study

INTRODUCTION

Primary aldosteronism is associated with impaired glucose tolerance. Whether plasma aldosterone and/or renin concentrations are associated with type 2 diabetes and continuous measures of glucose metabolism in the general population is still under debate.

RESEARCH DESIGN AND METHODS

The analyses included 2931 participants of the KORA F4 study at baseline and 2010 participants of the KORA FF4 study after a median follow-up of 6.5 years. The associations of active plasma renin and aldosterone concentrations with type 2 diabetes and continuous measures of glucose metabolism were assessed using logistic and linear regression models. Results were adjusted for sex, age, body mass index (BMI), estimated glomerular filtration rate, potassium, use of ACE inhibitors, angiotensin receptor blockers, beta blockers, diuretics and calcium channel blockers.

RESULTS

Cross-sectionally, renin was associated with type 2 diabetes (OR per SD: 1.25, 95% CI 1.10 to 1.43, p<0.001), fasting glucose, 2-hour glucose, insulin, proinsulin, HOMA-B (homeostasis model assessment of beta cell function) and HOMA-IR (homeostasis model assessment of insulin resistance) (all p values <0.001). Aldosterone was not associated with type 2 diabetes (OR: 1.04, 95% CI 0.91 to 1.19; p=0.547) but with insulin, proinsulin and HOMA-IR (all p values <0.001). The aldosterone-renin ratio was inversely associated with type 2 diabetes and several measures of glucose metabolism. Longitudinally, neither renin (OR: 1.12, 95% CI 0.92 to 1.36) nor aldosterone (OR: 0.91, 95% CI 0.74 to 1.11) were associated with incident type 2 diabetes. Renin was inversely associated with changes of insulin concentrations.

CONCLUSIONS

In the KORA F4/FF4 study, renin and aldosterone were not associated with incident type 2 diabetes and largely unrelated to changes of measures of glucose metabolism. Cross-sectionally, aldosterone was associated with surrogate parameters of insulin resistance. However, these associations were not independent of renin.

Relationship of Plasma Gremlin 1 Levels with Body Adiposity and Glycemic Control in Saudi Female Type 2 Diabetes Patients

OBJECTIVE

Gremlin 1 is a novel adipokine that plays an important role in obesity and type 2 diabetes mellitus (T2DM). In the current study, we aimed to evaluate plasma levels of Gremlin 1 in diabetic and non-diabetic Saudi adult females and its correlation with body composition, glycemic control and lipid profile.

METHODS

A case-control study was conducted among 41 T2DM and 31 non-diabetic adult age matched females (controls). All patients underwent body composition by bioelectrical impedance analysis, with a commercially available body analyzer. Fasting venous samples were analyzed for glycemic markers and lipids, while plasma Gremlin 1 was measured by ELISA. The results were compared between the two groups and correlated with other anthropometric and adiposity parameters.

RESULTS

Gremlin 1 levels were elevated in T2DM patients (345 ± 26 ng/mL) when compared to control subjects (272 ± 16 ng/mL, p < 0.05). Diabetic patients having poor glycemic control had significantly higher Gremlin 1 levels (382 ± 34 ng/mL) compared to patients with good glycemic control (291 ± 37 ng/mL, p < 0.05). Pearson correlation analysis revealed a positive correlation of Gremlin 1 with fat mass (r = 0.246, p = 0.012), HbA1C (r = 0.262, p = 0.008) and HOMA-IR index (r = 0.321, p = 0.001).

CONCLUSION

Our study demonstrates an important role of Gremlin 1 in glycemic control and body adiposity in the pathophysiology of obesity and T2DM. Gremlin 1 may emerge as a promising biomarker and therapeutic target in obesity and T2DM.

Association of serum uromodulin with adipokines in dependence of type 2 diabetes

BACKGROUND

The renal tubular glycoprotein uromodulin is associated with obesity and type 2 diabetes, but the underlying mechanisms are elusive. We investigated the association of serum uromodulin with adipokines and tested the effect modification by diabetes status.

METHODS

The associations of serum uromodulin with eight adipokines were assessed in 795-1080 participants of the KORA F4 study aged 62-81 years using linear regression models adjusted for sex, age, BMI, estimated glomerular filtration rate and diabetes. Significant associations were assessed for effect modification by diabetes status. We further tested using logistic regression whether adjustment for the significant adipokines affected the association of uromodulin with type 2 diabetes.

RESULTS

Serum uromodulin was inversely associated with chemerin and retinol-binding protein-4 after multivariable adjustment (p < 0.001) and Bonferroni correction for multiple testing. No significant association was observed between uromodulin and the other adipokines (leptin, adiponectin, secreted frizzled-related protein 5, progranulin, omentin-1 and vaspin) after correcting for multiple testing. The association of uromodulin with chemerin and retinol-binding protein-4 was stronger in participants with type 2 diabetes than in participants without diabetes (p for interaction < 0.05). However, inclusion of chemerin and retinol-binding protein-4 in logistic regression models did not attenuate the association of serum uromodulin with diabetes.

CONCLUSIONS

Serum uromodulin was inversely associated with the predominantly pro-inflammatory adipokines chemerin and retinol-binding protein-4. The associations were stronger in participants with type 2 diabetes compared to participants without diabetes. However, the association of serum uromodulin with type 2 diabetes was independent of chemerin and retinol-binding protein-4.

Omentin Is Independently Associated with Stroke Severity and Ipsilateral Carotid Artery Stenosis in Patients with Acute Cerebral Ischemia

Mounting evidence indicates an association between adipokines and inflammation-related atherosclerosis. Here, we sought to investigate the association of vaspin and omentin with clinical characteristics and outcomes of patients with acute cerebral ischemia (ACI). Consecutive ACI patients were evaluated within 24 h from symptom-onset. Stroke aetiology was classified using TOAST criteria. Adipokines were assayed using quantikine enzyme immunoassay commercially available kits. Stroke severity was assessed by NIHSS-score, and ipsilateral carotid stenosis (≥50% by NASCET criteria) by ultrasound and CT/MR angiography. Major cerebrovascular events were assessed at three months. We included 135 ACI patients (05 (78%) and 30 (22%) with acute ischemic stroke and transient ischemic attack, respectively; mean age ± SD: 59 ± 10 years; 68% men; median NIHSS-score: 3 (IQR:1–7)). Omentin was strongly correlated to admission stroke severity (Spearman rho coefficient: +0.303; p < 0.001). Patients with ipsilateral carotid stenosis had higher omentin levels compared to patients without stenosis (13.3 ± 8.9 ng/mL vs. 9.5 ± 5.5 ng/mL, p = 0.014). Increasing omentin levels were independently associated with higher stroke severity (linear regression coefficient = 0.290; 95%CI: 0.063–0.516; p = 0.002) and ipsilateral carotid stenosis (linear regression coefficient = 3.411; 95%CI: 0.194–6.628; p = 0.038). No association of vaspin with clinical characteristics and outcomes was found. Circulating omentin may represent a biomarker for the presence of atherosclerotic plaque, associated with higher stroke severity in ACI patients.

Novel biomarkers of inflammation, kidney function and chronic kidney disease in the general population

BACKGROUND

Inflammatory processes have been implicated in the development of chronic kidney disease (CKD). We investigated the association of a large panel of inflammatory biomarkers reflecting aspects of immunity with kidney function and CKD incidence.

METHODS

We used data from two independent population-based studies, KORA F4 (discovery, n = 1,110, mean age 70.3 years, 48.7% male) and ESTHER (replication, n = 1,672, mean age 61.9 years, 43.6% male). Serum levels of biomarkers were measured using proximity extension assay technology. The association of biomarkers with estimated glomerular filtration rate (eGFR) at baseline and with incident CKD was investigated using linear and logistic regression models adjusted for cardiorenal risk factors. Independent results from prospective analyses of both studies were pooled. The significance level was corrected for multiple testing by false-discovery rate (PFDR < 0.05.).

RESULTS

In the KORA F4 discovery study, 52 out of 71 inflammatory biomarkers were inversely associated with eGFR estimated based on serum creatinine. Top biomarkers included CD40, TNFRSF9 and IL10RB. Forty-two of these 52 biomarkers were replicated in the ESTHER study. Nine of the 42 biomarkers were associated with incident CKD independently of cardiorenal risk factors in the meta-analysis of the KORA (n = 142, mean follow-up of 6.5 years) and ESTHER (n = 103, mean follow-up of 8 years) studies. Pathway analysis revealed the involvement of inflammatory and immunomodulatory processes reflecting cross-communication of innate and adaptive immune cells.

CONCLUSIONS

Novel and known biomarkers of inflammation were reproducibly associated with kidney function. Future studies should investigate their clinical utility and underlying molecular mechanisms in independent cohorts.

Reversion from prediabetes to normoglycaemia after weight change in older persons: The KORA F4/FF4 study

BACKGROUND AND AIMS

In a non-interventional study of older persons, we assessed the impact of changes in BMI and waist circumference (WC) on reversion from glucose- and HbA1c-defined prediabetes to normoglycaemia (in short: reversion) and on persistence of normoglycaemia. Moreover, we studied whether reversion reduced cardiovascular risk.

METHODS AND RESULTS

From the population-based KORA S4/F4/FF4 cohort study conducted in Southern Germany, we utilized data from the second and third visit to the study center (median follow-up 6.5 years). We used two overlapping data sets, one with 563 persons with HbA1c<6.5% (mean age 69 years, 51.5% men), one with 510 persons with glucose-based prediabetes or normal glucose tolerance. We calculated proportions of reversion, and estimated adjusted relative risks for the association between initial BMI/WC and change of BMI/WC, respectively, and reversion (and persistence of normoglycaemia, respectively). We estimated 10-year cardiovascular risks using the Framingham 2008 score. Overall, 27.3% of persons with HbA1c-defined prediabetes and 9.2% of persons with glucose-based prediabetes returned to normoglycaemia during follow-up. Lower initial BMI/WC and reduction of BMI/WC were associated with larger probabilities of returning to normoglycaemia (e.g., for HbA1c 5.7-6.4%, RR = 1.24 (95% CI: 1.09-1.41) per 1 kg/m² decline of BMI). Moreover, reduction of BMI/WC increased probabilities of maintaining normoglycaemia (e.g., for glucose-based prediabetes, RR = 1.09 (1.02-1.16) per 1 kg/m² decline of BMI). 10-year cardiovascular risk was 5.6 (1.7-9.6) percentage points lower after reversion from glucose-based prediabetes to normoglycaemia.

CONCLUSION

In older adults, even moderate weight reduction contributes to reversion from prediabetes to normoglycaemia and to maintaining normoglycaemia.

Newly Discovered Adipokines: Pathophysiological Link Between Obesity and Cardiometabolic Disorders

With the increasing prevalence of obesity, obesity-related problems such as cardiometabolic disorders (CMD), are also rapidly increasing. To prevent and alleviate the progressive course of CMD, it is important to discover the pathophysiological mechanisms between obesity and CMD. Adipose tissue is now recognized as an active endocrine organ that releases adipokines. Adipokines play a pivotal role in chronic low-grade inflammation, oxidative stress, and impaired insulin signaling, contributing to metabolic derangement and leading to CMD. Recent studies have provided substantial evidence supporting the association between adipokines and CMD. In this review, we highlight the pathophysiological action of adipokines in CMD that includes metabolic syndrome, type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular diseases. We focused on translational and clinical research of novel adipokines associated with metabolic and cardiovascular regulation. Exploration of the role of these adipokines connecting obesity and CMD may provide a perspective on adipokine-based therapeutic implications for CMD.

Higher circulating omentin is associated with increased risk of primary cardiovascular events in individuals with diabetes

AIMS/HYPOTHESIS

Higher concentrations of the adipokine omentin are associated with lower levels of cardiometabolic risk factors in experimental and cross-sectional studies, but with higher risk of type 2 diabetes and cardiovascular diseases in population-based cohort studies. However, it is unknown whether high omentin concentrations are associated with increased risk of cardiovascular events in people with established diabetes. Therefore, the present study investigated the association between serum omentin concentrations and the risk of cardiovascular events in individuals with diabetes.

METHODS

This prospective study was based on participants of the German ESTHER cohort with diabetes and without previous cardiovascular event. The ESTHER cohort consists of individuals aged 50-75 years at baseline who were recruited by their general practitioners. After exclusion of individuals with serum C-reactive protein ≥10 mg/l (≥95.24 nmol/l), the final analysis population consisted of 933 individuals. At baseline, serum omentin concentrations were measured by ELISA. Cox regression models were fitted to estimate HRs and their corresponding 95% CIs for associations of omentin tertiles with a composite endpoint of cardiovascular events and separately with incident myocardial infarction, stroke and cardiovascular death.

RESULTS

During 14 years of follow-up, 228 individuals experienced a primary cardiovascular event (myocardial infarction, stroke or cardiovascular death). After comprehensive adjustment for age, sex, BMI, metabolic and lifestyle factors and medication use, HRs (95% CIs) for the 2nd and 3rd tertile of omentin compared with the 1st tertile were: 1.24 (95% CI 0.86, 1.79) and 1.63 (1.15, 2.32) (p_trend = 0.005) for the composite cardiovascular endpoint; 1.39 (0.78, 2.47) and 1.71 (0.98, 2.99) (p_trend = 0.065) for incident myocardial infarction; 1.40 (0.78, 2.53) and 2.05 (1.17, 3.58) (p_trend = 0.010) for incident stroke; and 1.43 (0.85, 2.40) and 1.72 (1.04, 2.83) (p_trend = 0.040) for cardiovascular death. Effect estimates and p values were almost unaltered after additional adjustment for adiponectin.

CONCLUSIONS/INTERPRETATION

Higher omentin concentrations are associated with an increased risk for cardiovascular events in individuals with diabetes after adjustment for multiple cardiovascular risk factors. Given data from preclinical studies, it appears possible that this association reflects a compensatory, but insufficient upregulation of omentin concentrations as a response to stimuli that increase cardiovascular risk.

Increased Release of Proinflammatory Proteins in Primary Human Adipocytes and Activation of the Inflammatory NFĸB, p38, and ERK Pathways upon Omentin Treatment

OBJECTIVES

To investigate the impact of omentin on the release of inflammation-related biomarkers and inflammatory pathways in primary human adipocytes.

METHODS

Adipocytes were treated with or without omentin (500 and 2,000 ng/mL), and the supernatants were analyzed for inflammation-related biomarkers using proximity extension assay technology. Potential upstream regulators of the omentin-stimulated proteins were identified using Ingenuity Pathway Analysis. Protein levels of components of inflammatory pathways were measured using Western blotting.

RESULTS

2,000 ng/mL omentin induced the release of 30 biomarkers 97.1 ± 31.1-fold in the supernatants (all p < 0.05). Most biomarkers were proin-flammatory chemokines and cytokines. We identified the transcription factor nuclear factor "kappa-light-chain-enhancer" of activated B cells (NFĸB) and the kinases p38 and extracellular signal-regulated kinase (ERK)1/2 as potential upstream regulators in silico. On the cellular level, treatment with 2,000 ng/mL omentin for 24 h enhanced the phosphorylation levels of NFĸB 2.1 ± 0.3-fold (p < 0.05), of p38 2.6 ± 0.4-fold (p < 0.05), and of ERK1/2 1.8 ± 0.2-fold (p < 0.05).

CONCLUSIONS

These data argue that omentin exerts proinflammatory effects through the activation of the inflammatory NFĸB, p38, and ERK1/2 pathways in cultured primary adipocytes.

The association between omentin and diabetes: a systematic review and meta-analysis of observational studies

AIMS

A number of studies have examined the association between the serum levels of omentin and diabetes, but the findings have been inconclusive. Herein, we systematically reviewed available observational studies to elucidate the overall relationship between omentin and diabetes, including type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and impaired glucose tolerance (IGT) among adolescent and adult population.

METHODS

PubMed, Cochrane's Library, Science Direct, Scopus, Google Scholar, and ISI Web of Science databases were searched for all available literature until January 2019 for studies assessing the association between omentin and diabetes. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of each study.

RESULTS

A total of 28 articles met the inclusion criteria and were included in our systematic review and meta-analysis. There was a significant association between serum omentin and diabetes (WMD-1.68; 95% CI, -2.17 to -1.19; P<0.001). The result of our sub-group analysis based on participants' health status revealed that omentin was significantly lower in T2DM and IGT subjects but not in T1DM ones compared to healthy controls.

CONCLUSION

We found that serum omentin level is significantly lower in T2DM and IGT patients but not in T1DM ones. These data could be used by clinicians for early diagnosis and management of diabetes. Furthermore, we need more clinical trials to investigate new agents which could influence omentin levels.

Omentin-regulated proteins combine a pro-inflammatory phenotype with an anti-inflammatory counterregulation in human adipocytes: A proteomics analysis

AIMS

Experimental and epidemiological studies reported controversial data on the role of omentin in type 2 diabetes and cardiovascular diseases. This study aimed to characterise the impact of omentin on the secretome of human adipocytes to analyse the enrichment of these proteins in metabolic and cellular signalling pathways underlying its physiological function.

MATERIAL/METHODS

Differentiated primary human adipocytes were treated without or with 500 or 2000 ng/mL omentin for 24 hours. The secretome was analysed by liquid chromatography coupled tandem-mass spectrometry. Differences in protein secretion between untreated and omentin-treated adipocytes were compared using a paired t-test. Other potential upstream regulators and the overrepresentation in canonical pathways of omentin-stimulated proteins were analysed using Ingenuity Pathway Analysis.

RESULTS

The supernatant of adipocytes contained 3493 proteins, of which 140 were differentially secreted by both concentrations of omentin compared with untreated adipocytes. Among the most strongly increased proteins, tumour necrosis factor-inducible gene 6 protein (TNFAIP6) was increased by 140-fold in the supernatant. Omentin-regulated proteins were overrepresented in seven canonical pathways including eukaryotic initiation factor 2 signalling, complement system, and inhibition of matrix metalloproteases. We further identified 25 other potential upstream activators of omentin-regulated proteins, mainly pro-inflammatory cytokines and transcription regulators including NFκB.

CONCLUSIONS

In differentiated human adipocytes, the release of the anti-inflammatory TNFAIP6 might be part of a counterregulatory response to the pro-inflammatory action of omentin. Omentin-regulated proteins were overrepresented in pathways indicating cellular stress, a pro-inflammatory environment and a crosstalk with other organs. Other potential activators of omentin-regulated proteins point towards a central role of NFκB activation in the omentin-induced secretory process.

Protein markers and risk of type 2 diabetes and prediabetes: a targeted proteomics approach in the KORA F4/FF4 study

The objective of the present study was to identify proteins that contribute to pathophysiology and allow prediction of incident type 2 diabetes or incident prediabetes. We quantified 14 candidate proteins using targeted mass spectrometry in plasma samples of the prospective, population-based German KORA F4/FF4 study (6.5-year follow-up). 892 participants aged 42–81 years were selected using a case-cohort design, including 123 persons with incident type 2 diabetes and 255 persons with incident WHO-defined prediabetes. Prospective associations between protein levels and diabetes, prediabetes as well as continuous fasting and 2 h glucose, fasting insulin and insulin resistance were investigated using regression models adjusted for established risk factors. The best predictive panel of proteins on top of a non-invasive risk factor model or on top of HbA1c, age, and sex was selected. Mannan-binding lectin serine peptidase (MASP) levels were positively associated with both incident type 2 diabetes and prediabetes. Adiponectin was inversely associated with incident type 2 diabetes. MASP, adiponectin, apolipoprotein A-IV, apolipoprotein C-II, C-reactive protein, and glycosylphosphatidylinositol specific phospholipase D1 were associated with individual continuous outcomes. The combination of MASP, apolipoprotein E (apoE) and adiponectin improved diabetes prediction on top of both reference models, while prediabetes prediction was improved by MASP plus CRP on top of the HbA1c model. In conclusion, our mass spectrometric approach revealed a novel association of MASP with incident type 2 diabetes and incident prediabetes. In combination, MASP, adiponectin and apoE improved type 2 diabetes prediction beyond non-invasive risk factors or HbA1c, age and sex.

Adipocytokine correlations with thyroid function and autoimmunity in euthyroid sardinians

OBJECTIVE

Cytokines release by adipocytes could interact with TSH secretion. We evaluated the relationship between adipocytokines and TSH. We further tested for association of cytokines and thyroid autoimmunity.

METHODS

We conducted a cross-sectional study in a community-based sample including 5385 individuals (2964 female) with TSH within the reference range. Subjects who reported taking thyroid medications or drugs that alter thyroid function were excluded. TSH, FT4, adiponectin, leptin, antibody against thyroperoxidase and against thyroglobulin were measured. Linear and logistic regression models were used to test for association.

RESULTS

Females had higher adiponectin and leptin level and increased frequency of thyroid antibodies. In multiple regression analysis TSH was directly associated with leptin (β = 0.003, p = 0.001) and the presence of circulating antibody against thyroperoxidase (β = 0.315, p < 0.001), but negatively associated with age (β = -0.012, p < 0.001) and FT4 (β = -0.359, p < 0.001). Adiponectin, the presence of antibody against thyroglobulin and smoking habit were not associated with TSH levels (p = 0.223, p = 0.174 and p = 0.788, respectively). Logistic regression analysis revealed that higher adiponectin levels were associated with thyroid autoimmunity.

CONCLUSIONS

Leptin is positively associated with TSH levels in euthyroid individuals, suggesting an effect of the adipokine on TSH secretion. Our results support the hypothesis that the leptin and pituitary-thyroid axis might interact in the context of energy homeostasis. The effect of adiponectin on thyroid autoimmunity will require more studies.

Myeloperoxidase, superoxide dismutase-3, cardiometabolic risk factors, and distal sensorimotor polyneuropathy: The KORA F4/FF4 study

BACKGROUND

Oxidative stress has been proposed as important pathomechanism of cardiometabolic diseases and distal sensorimotor polyneuropathy (DSPN). However, the relevance of biomarkers of oxidative stress has not been investigated in this context. Therefore, this study aimed to assess the association of the prooxidant myeloperoxidase (MPO) and the antioxidant extracellular superoxide dismutase (SOD3) with cardiometabolic risk factors and with prevalence and incidence of DSPN.

METHODS

Cross-sectional analyses comprised 1069 participants (40.3% with prediabetes and 20.5% with type 2 diabetes) of the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4 study (2006-2008), 181 of whom had DSPN at baseline. Prospective analyses included 524 individuals without DSPN at baseline who also participated in the KORA FF4 study (2013-2014), 132 of whom developed DSPN during the 6.5-year follow-up. Serum MPO and SOD3 were measured by ELISA, and their association with cardiometabolic risk factors and DSPN were estimated by using linear and logistic regression analyses.

RESULTS

Higher MPO and SOD levels showed multiple positive associations with cardiometabolic risk factors including age, indices of obesity, insulin resistance, serum lipids, renal dysfunction, and biomarkers of inflammation. Higher MPO levels were associated with prevalent DSPN (fully adjusted OR 1.38 [95% CI 1.10; 1.72] per doubling of MPO). Higher baseline SOD3 levels were related to incident DSPN (age and sex-adjusted OR 2.14 [1.02; 4.48] per doubling of SOD3), which was partially explained by cardiometabolic risk factors.

CONCLUSIONS

Systemic levels of both pro- and antioxidant enzymes appear involved in cardiometabolic risk and development of DSPN.