A Prospective Analysis of the Metyrapone Short Test Using Targeted and Untargeted Metabolomics.

INTRODUCTION: The present study aimed to prove the metyrapone short test in a day clinic to be suitable for examining the integrity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with suspected secondary and tertiary adrenal insufficiency and to identify novel effector molecules in acute stress response. METHODS: 44 patients were prospectively enrolled. Based on stimulated 11-deoxycortisol levels, patients were divided into a physiological (11-deoxycortisol ≥70 µg/L) and a pathological (11-deoxycortisol <70 µg/L) response group. Clinical follow-up examination was performed for validation. Ultraperformance liquid chromatography tandem mass spectrometry and a Fourier-transform-ion-cyclotron-resonance-mass-spectrometry were used for targeted and untargeted steroid metabolomics. RESULTS: At baseline, lower levels of cortisone (42 vs. 50 nmol/L, p = 0.048) and 17-OH-progesterone (0.6 vs. 1.2 nmol/L, p = 0.041) were noted in the pathological response group. After metyrapone administration, the pathological response group exhibited significantly lower 11-deoxycortisol (39.0 vs. 94.2 µg/L, p < 0.001) and ACTH (49 vs. 113 pg/mL, p < 0.001) concentrations as well as altered upstream metabolites. Untargeted metabolomics identified a total of 76 metabolites to be significantly up- or downregulated by metyrapone. A significant increase of the bile acid glycochenodeoxycholic acid (GCDC, p < 0.01) was detected in both groups with an even stronger increase in the physiological response group. After a mean follow-up of 17.2 months, an 11-deoxycortisol cut-off of 70 µg/L showed a high diagnostic performance (sensitivity 100%, specificity 96%). CONCLUSION: The metyrapone short test is safe and feasible in a day clinic setting. The alterations of the bile acid GCDC indicate that the liver might be involved in the acute stress response of the HPA axis.

Cohort profile: the Food Chain Plus (FoCus) cohort.

The Food Chain Plus (FoCus) cohort was launched in 2011 for population-based research related to metabolic inflammation. To characterize this novel pathology in a comprehensive manner, data collection included multiple omics layers such as phenomics, microbiomics, metabolomics, genomics, and metagenomics as well as nutrition profiling, taste perception phenotyping and social network analysis. The cohort was set-up to represent a Northern German population of the Kiel region. Two-step recruitment included the randomised enrolment of participants via residents' registration offices and via the Obesity Outpatient Centre of the University Medical Center Schleswig-Holstein (UKSH). Hence, both a population- and metabolic inflammation- based cohort was created. In total, 1795 individuals were analysed at baseline. Baseline data collection took place between 2011 and 2014, including 63% females and 37% males with an age range of 18-83 years. The median age of all participants was 52.0 years [IQR: 42.5; 63.0 years] and the median baseline BMI in the study population was 27.7 kg/m2 [IQR: 23.7; 35.9 kg/m2]. In the baseline cohort, 14.1% of participants had type 2 diabetes mellitus, which was more prevalent in the subjects of the metabolic inflammation group (MIG; 31.8%). Follow-up for the assessment of disease progression, as well as the onset of new diseases with changes in subject's phenotype, diet or lifestyle factors is planned every 5 years. The first follow-up period was finished in 2020 and included 820 subjects.

Secreted frizzled-related protein 5 serum levels in human periodontitis-A nested case-control study.

AIM: Recombinant secreted frizzled-related protein 5 (sFRP5) improved periodontal status in mice. Thus, this study aimed to investigate this finding in human periodontitis using an epidemiological approach. MATERIALS AND METHODS: sFRP5 and wnt5a concentrations were determined in human serum from the Food Chain Plus cohort using ELISAs. A total of 128 patients with periodontitis and tooth loss and 245 patients with periodontitis without tooth loss were compared to 373 sex-, smoker-, age- and BMI-matched individuals in a nested case-control design. RESULTS: Systemic sFRP5 serum levels were significantly lower in patients with periodontitis and tooth loss (2.5 [0.0-10.4] ng/ml, median [IQR]) compared to patients with periodontitis without tooth loss (6.0 [2.5-15.8] ng/ml, median [IQR], p = 0.04] and matched controls (7.0 [2.5-18.3] ng/ml, median [IQR], p = 0.02). No significant differences in sFRP5 serum levels were found among patients with periodontitis without tooth loss (6.0 [2.5-15.8] ng/ml, median [IQR]) and controls (3.1 [0.0-10.6] ng/ml, median [IQR], p = 0.06). CONCLUSIONS: sFRP5 might serve as a novel biomarker for periodontitis severity. Modulating the inflammatory background of severe forms of periodontitis, in the time of precision medicine, needs to be revealed in further studies.

IL-6 blockade by monoclonal antibodies inhibits apolipoprotein (a) expression and lipoprotein (a) synthesis in humans.

Lipoprotein (a) [Lp(a)] is a highly atherogenic lipid particle. Although earlier reports suggested that Lp(a) levels are mostly determined by genetic factors, several recent studies have revealed that Lp(a) induction is also caused by chronic inflammation. Therefore, we aimed to examine whether cytokine blockade by monoclonal antibodies may inhibit Lp(a) metabolism. We found that interleukin 6 (IL-6) blockade by tocilizumab (TCZ) reduced Lp(a) while TNF-α-inhibition by adalimumab in humans had no effect. The specificity of IL-6 in regulating Lp(a) was further demonstrated by serological measurements of human subjects (n = 1,153) revealing that Lp(a) levels are increased in individuals with elevated serum IL-6. Transcriptomic analysis of human liver biopsies (n = 57) revealed typical IL-6 response genes being correlated with the LPA gene expression in vivo. On a molecular level, we found that TCZ inhibited IL-6-induced LPA mRNA and protein expression in human hepatocytes. Furthermore, examination of IL-6-responsive signal transducer and activator of transcription 3 binding sites within the LPA promoter by reporter gene assays, promoter deletion experiments, and electrophoretic mobility shift assay analysis showed that the Lp(a)-lowering effect of TCZ is specifically mediated via a responsive element at -46 to -40. Therefore, IL-6 blockade might be a potential therapeutic option to treat elevated Lp(a) serum concentrations in humans and might be a noninvasive alternative to lipid apheresis in the future.

Soluble receptor for advanced glycation end products as a potential biomarker to predict weight loss and improvement of insulin sensitivity by a very low calorie diet of obese human subjects.

INTRODUCTION: Obesity is associated with low-grade systemic inflammation which is thought to trigger the development of comorbidities such as type 2 diabetes. The soluble receptor for advanced glycation end products (sRAGE) belongs to the innate immune system and has been linked to obesity, recently. The aim of the present study was to examine whether serum sRAGE concentrations are related to the grade of weight loss and improvement of insulin resistance due to a very low calorie diet (VLCD). METHODS: 22 severe obese subjects (Median Body Mass Index (BMI): 44.5kg/m(2)) were included in a dietary intervention study of 6month, consisting of a very low calorie formula diet phase (VLCD: 800kcal/d) for 12 weeks and a following 12 week weight maintenance phase. Fasting glucose, fasting insulin, adiponectin, leptin and sRAGE were determined from sera. Insulin sensitivity was estimated by Homeostasis Model Assessment (HOMA) index and leptin-to-adiponectin-ratio (LAR). RESULTS: Mean body weight reduction by VLCD accounted to 21.7kg with a significant improvement of insulin resistance. At baseline, sRAGE serum levels were significantly inversely related to BMI (rS=-0.642, p=0.001) and HOMA (rS=-0.419, p=0.041). Of interest, sRAGE serum levels at baseline were significantly lower in study subjects with greater reduction of BMI (p=0.017). In addition, a significantly greater HOMA reduction was observed in subjects with lower sRAGE serum levels at baseline (p=0.006). Finally, correlation analysis revealed, that changes of sRAGE serum levels were significantly correlated to changes of BMI (rS=-0.650, p=0.022) during intervention. CONCLUSION: Anti-inflammatory sRAGE might be a potential future biomarker to predict weight loss and improvement of insulin resistance by a VLCD whereby lower baseline sRAGE serum levels indicate a better outcome of the dietary intervention.

Interleukin-6 and tumour necrosis factor-α differentially regulate lincRNA transcripts in cells of the innate immune system in vivo in human subjects with rheumatoid arthritis.

lincRNAs recently have been discovered as evolutionary conserved transcripts of non-coding DNA sequences and have been implicated in the regulation of cellular differentiation. In humans, molecular studies have suggested a functional role for lincRNAs in cancer development. The aim of the present study was to examine whether these novel molecules are specifically regulated by different cytokines in cells of the innate immune system in humans in vivo and whether lincRNAs thereby might be involved in the pathophysiology of rheumatoid arthritis (RA). Therefore, CD14(+) monocytes were isolated from RA patients before and after anti-IL-6R (tocilizumab) or anti-TNF-α (adalimumab) therapy and lincRNA transcription was analysed by a microarray based experiment. As expected, we found lincRNAs to be present in CD14(+) monocytes of RA patients. However, of the total number of 7.419 lincRNAs examined in this study only a very small number was significantly regulated by either IL-6 or TNF-α (85 lincRNAs, corresponding to 1.1%). The numbers of lincRNAs regulated was higher due to TNF-α compared to IL-6. Interestingly, none of the identified lincRNAs was influenced by both, IL-6 and TNF-α, suggesting the regulation of lincRNA transcription to be highly specific for distinct cytokines. Taken together, our results suggest (1) that lincRNAs are novel intracellular molecular effectors of specific cytokines in cells of the innate immune system in humans in vivo and (2) that lincRNAs might be involved in the molecular pathophysiology of RA.

Effects of lifestyle and associated diseases on serum CC16 suggest complex interactions among metabolism, heart and lungs.

INTRODUCTION: Clara cell 16-kDa protein (CC16) is an anti-inflammatory, immunomodulatory secreted pulmonary protein with reduced serum concentrations in obesity according to recent data. OBJECTIVE: Studies focused solely on bodyweight, which does not properly reflect obesity-associated implications of the metabolic and reno-cardio-vascular system. The purpose of this study was therefore to examine CC16 in a broad physiological context considering cardio-metabolic comorbidities of primary pulmonary diseases. METHODS: CC16 was quantified in serum samples in a subset of the FoCus (N = 497) and two weight loss intervention cohorts (N = 99) using ELISA. Correlation and general linear regression analyses were applied to assess CC16 effects of lifestyle, gut microbiota, disease occurrence and treatment strategies. Importance and intercorrelation of determinants were validated using random forest algorithms. RESULTS: CC16 A38G gene mutation, smoking and low microbial diversity significantly decreased CC16. Pre-menopausal female displayed lower CC16 compared to post-menopausal female and male participants. Biological age and uricosuric medications increased CC16 (all p < 0.01). Adjusted linear regression revealed CC16 lowering effects of high waist-to-hip ratio (est. -11.19 [-19.4; -2.97], p = 7.99 × 10-3), severe obesity (est. -2.58 [-4.33; -0.82], p = 4.14 × 10-3) and hypertension (est. -4.31 [-7.5; -1.12], p = 8.48 × 10-3). ACEi/ARB medication (p = 2.5 × 10-2) and chronic heart failure (est. 4.69 [1.37; 8.02], p = 5.91 × 10-3) presented increasing effects on CC16. Mild associations of CC16 were observed with blood pressure, HOMA-IR and NT-proBNP, but not manifest hyperlipidemia, type 2 diabetes, diet quality and dietary weight loss intervention. CONCLUSION: A role of metabolic and cardiovascular abnormalities in the regulation of CC16 and its modifiability by behavioral and pharmacological interventions is indicated. Alterations by ACEi/ARB and uricosurics could point towards regulatory axes comprising the renin-angiotensin-aldosterone system and purine metabolism. Findings altogether strengthen the importance of interactions among metabolism, heart and lungs.

Dipeptidylpeptidase (DPP)-4 inhibitor therapy increases circulating levels of anti-inflammatory soluble frizzle receptor protein (sFRP)-5 which is decreased in severe COVID-19 disease.

Obesity and type 2 diabetes (T2D) show an increased risk for a severe COVID-19 disease. Treatment with DPP4 inhibitor (DPP4i) results in reduced mortality and better clinical outcome. Here, we aimed to identify potential mechanisms for the observed DPP4i effect in COVID-19. Comparing T2D subjects with and without DPP4i treatment, we identified a significant increase of the anti-inflammatory adipokine sFRP5 in relation to DPP4 inhibition. sFRP5 is a specific antagonist to Wnt5a, a glycopeptide secreted by adipose tissue macrophages acting pro-inflammatory in various diseases. We therefore examined sFRP5 levels in patients hospitalised for severe COVID-19 and found significant lower levels compared to healthy controls. Since sFRP5 might consequently be a molecular link for the beneficial effects of DPP4i in COVID-19, we further aimed to identify the exact source of sFRP5 in adipose tissue on cellular level. We therefore isolated pre-adipocytes, mature adipocytes and macrophages from adipose tissue biopsies and performed western-blotting. Results showed a sFRP5 expression specifically in mature adipocytes of subcutaneous and omental adipose tissue. In summary, our data suggest that DPP4i increase serum levels of anti-inflammatory sFRP5 which might be beneficial in COVID-19, reflecting a state of sFRP5 deficiency.

Differential Effects of Obesity, Hyperlipidaemia, Dietary Intake and Physical Inactivity on Type I versus Type IV Allergies.

BACKGROUND: Alongside metabolic diseases (esp. obesity), allergic disorders are becoming increasingly prevalent. Since both obesity and allergies are highly impacted by environmental determinants, with this study we assessed the potential link between metabolic implications and two distinct types of allergies. METHODS: Using cross-sectional data from the German FoCus cohort, n = 385 allergy cases, either hay fever (=type I allergy, n = 183) or contact allergy (=type IV allergy, n = 202) were compared to age- and sex-matched healthy control subjects (1:1 ratio, in total n = 770) regarding their metabolic phenotype, diet, physical activity, sleep, gut microbial composition, and serum metabolite profile using suitable BMI-adjusted models. RESULTS: Obesity and metabolic alterations were found significantly more prevalent in subjects with allergies. In fact, this relation was more pronounced in contact allergy than hay fever. Subsequent BMI-adjusted analysis reveals particular importance of co-occurring hyperlipidaemia for both allergy types. For contact allergy, we revealed a strong association to the dietary intake of poly-unsaturated fatty acids, particularly α-linolenic acid, as well as the enrichment of the corresponding metabolic pathway. For hay fever, there were no major associations to the diet but to a lower physical activity level, shorter duration of sleep, and an altered gut microbial composition. Finally, genetic predisposition for hyperlipidaemia was associated to both contact allergy and hay fever. CONCLUSIONS: Reflected by higher allergy prevalence, our findings indicate an impaired immune response in obesity and hyperlipidaemia, which is differentially regulated in type I and type IV allergies by an unfavourable lifestyle constellation and subsequent microbial and metabolic dysfunctions.

Brief Research Report: Serum clara cell 16 kDa protein levels are increased in patients hospitalized for severe SARS-CoV-2 or sepsis infection.

Background: Clara cell 16 kDa protein (CC16) is a secretory protein primarily expressed in epithelial cells in the lungs. Previous studies show that CC16 exerts anti-inflammatory and immune-modulatory properties in both acute and chronic pulmonary diseases. However, despite the evidence of CC16's high biomarker potential, evaluation of its role in infectious diseases is yet very limited. Methods: Serum CC16 concentrations were measured by ELISA and assessed in two different types of severe infections. Using a case-control study design, patients treated for either severe SARS-CoV-2 or severe non-pulmonary sepsis infection were compared to age- and sex-matched healthy human subjects. Results: Serum CC16 was significantly increased in both types of infection (SARS-CoV-2: 96.22 ± 129.01 ng/ml vs. healthy controls: 14.05 ± 7.48 ng/ml, p = 0.022; sepsis: 35.37 ± 28.10 ng/ml vs. healthy controls: 15.25 ± 7.51 ng/ml, p = 0.032) but there were no distinct differences between infections with and without pulmonary focus (p = 0.089). Furthermore, CC16 serum levels were positively correlated to disease duration and inversely to the platelet count in severe SARS-CoV-2 infection. Conclusions: Increased CC16 serum levels in both SARS-CoV-2 and sepsis reinforce the high potential as a biomarker for epithelial cell damage and bronchoalveolar-blood barrier leakage in pulmonary as well as non-pulmonary infectious diseases.

A dietary carbohydrate - gut Parasutterella - human fatty acid biosynthesis metabolic axis in obesity and type 2 diabetes.

Recent rodent microbiome experiments suggest that besides Akkermansia, Parasutterella sp. are important in type 2 diabetes and obesity development. In the present translational human study, we aimed to characterize Parasutterella in our European cross-sectional FoCus cohort (n = 1,544) followed by validation of the major results in an independent Canadian cohort (n = 438). In addition, we examined Parasutterella abundance in response to a weight loss intervention (n = 55). Parasutterella was positively associated with BMI and type 2 diabetes independently of the reduced microbiome α/ß diversity and low-grade inflammation commonly found in obesity. Nutritional analysis revealed a positive association with the dietary intake of carbohydrates but not with fat or protein consumption. Out of 126 serum metabolites differentially detectable by untargeted HPLC-based MS-metabolomics, L-cysteine showed the strongest reduction in subjects with high Parasutterella abundance. This is of interest, since Parasutterella is a known high L-cysteine consumer and L-cysteine is known to improve blood glucose levels in rodents. Furthermore, metabolic network enrichment analysis identified an association of high Parasutterella abundance with the activation of the human fatty acid biosynthesis pathway suggesting a mechanism for body weight gain. This is supported by a significant reduction of the Parasutterella abundance during our weight loss intervention. Together, these data indicate a role for Parasutterella in human type 2 diabetes and obesity, whereby the link to L-cysteine might be relevant in type 2 diabetes development and the link to the fatty acid biosynthesis pathway for body weight gain in response to a carbohydrate-rich diet in obesity development.

BMI, Alcohol Consumption and Gut Microbiome Species Richness Are Related to Structural and Functional Neurological Abnormalities.

Background: The incidence of neurological diseases is increasing throughout the world. The aim of the present study was to identify nutrition and microbiome factors related to structural and functional neurological abnormalities to optimize future preventive strategies. Methods: Two hundred thirty-eight patients suffering from (1) structural (neurodegeneration) or (2) functional (epilepsy) neurological abnormalities or (3) chronic pain (migraine) and 612 healthy control subjects were analyzed by validated 12-month food frequency questionnaire (FFQ) and 16S rRNA microbiome sequencing (from stool samples). A binomial logistic regression model was applied for risk calculation and functional pathway analysis to show which functional pathway could discriminate cases and healthy controls. Results: Detailed analysis of more than 60 macro- and micronutrients revealed no distinct significant difference between cases and controls, whereas BMI, insulin resistance and metabolic inflammation in addition to alcohol consumption were major drivers of an overall neurological disease risk. The gut microbiome analysis showed decreased alpha diversity (Shannon index: p = 9.1× 10-7) and species richness (p = 1.2 × 10-8) in the case group as well as significant differences in beta diversity between cases and controls (Bray-Curtis: p = 9.99 × 10-4; Jaccard: p = 9.99 × 10-4). The Shannon index showed a beneficial effect (OR = 0.59 (95%-CI (0.40, 0.87); p = 8 × 10-3). Cases were clearly discriminated from healthy controls by environmental information processing, signal transduction, two component system and membrane transport as significantly different functional pathways. Conclusions: In conclusion, our data indicate that an overall healthy lifestyle, in contrast to supplementation of single micro- or macronutrients, is most likely to reduce overall neurological abnormality risk and that the gut microbiome is an interesting target to develop novel preventive strategies.

Effect of various weight loss interventions on serum NT-proBNP concentration in severe obese subjects without clinical manifest heart failure.

Obesity is associated with a "natriuretic handicap" indicated by reduced N-terminal fragment of proBNP (NT-proBNP) concentration. While gastric bypass surgery improves the natriuretic handicap, it is presently unclear if sleeve gastrectomy exhibits similar effects. We examined NT-proBNP serum concentration in n = 72 obese participants without heart failure before and 6 months after sleeve gastrectomy (n = 28), gastric bypass surgery (n = 19), and 3-month 800 kcal/day very-low calorie diet (n = 25). A significant weight loss was observed in all intervention groups. Within 6 months, NT-proBNP concentration tended to increase by a median of 44.3 pg/mL in the sleeve gastrectomy group (p = 0.07), while it remained unchanged in the other groups (all p ≥ 0.50). To gain insights into potential effectors, we additionally analyzed NT-proBNP serum concentration in n = 387 individuals with different metabolic phenotypes. Here, higher NT-proBNP levels were associated with lower nutritional fat and protein but not with carbohydrate intake. Of interest, NT-proBNP serum concentrations were inversely correlated with fasting glucose concentration in euglycemic individuals but not in individuals with prediabetes or type 2 diabetes. In conclusion, sleeve gastrectomy tended to increase NT-proBNP levels in obese individuals and might improve the obesity-associated "natriuretic handicap". Thereby, nutritional fat and protein intake and the individual glucose homeostasis might be metabolic determinants of NT-proBNP serum concentration.

Differential effects of protein intake versus intake of a defined oligopeptide on FGF-21 in obese human subjects in vivo.

BACKGROUND: FGF-21 is described as a powerful metabolic regulator with beneficial effects including glucose-lowering and improvement of insulin sensitivity without hypoglycaemia. On the other hand, FGF-21 is activated when muscle and other tissues are stressed by external effects or internal cellular pathogens that lead to shortcomings in metabolic balance. Previous results suggested that FGF-21 could be a promising target to develop future metabolic therapeutics. PURPOSE: The present study was performed to gain deeper insight into the regulation of FGF-21 by protein metabolism in obese human subjects. METHODS: FGF-21 serum concentrations were measured in a cohort of n = 246 obese humans ± type 2 diabetes mellitus (T2DM) (median age 53.0 [46.0; 60.0] years and BMI 40.43 [35.11; 47.24] kg/m2) and related to the nutritional protein intake. In addition, the effect of a novel oligopeptide purified from a ß-casein hydrolysate on FGF-21 was examined in vitro in liver cells and in vivo in a human intervention study with the main focus on metabolic inflammation including 40 mainly obese subjects (mean age 41.08 ± 9.76 years, mean BMI 38.29 ± 9.4 kg/m2) in a randomized 20 weeks double-blind cross-over design. MAIN FINDINGS: In the cohort analysis, FGF-21 serum concentrations were significant lower with higher protein intake in obese subjects without T2DM but not in obese subjects with T2DM. Furthermore, relative methionine intake was inversely related to FGF-21. While global protein intake in obesity was inversely associated with FGF-21, incubation of HepG2 cells with a ß-casein oligopeptide increased FGF-21 expression in vitro. This stimulatory effect was also present in vivo, since in the clinical intervention study treatment of obese subjects with the ß-casein oligopeptide for 8 weeks significantly increased FGF-21 serum levels from W0 = 23.86 pg/mL to W8 = 30.54 pg/mL (p < 0.001), while no increase was found for placebo. CONCLUSION: While the total nutritional protein intake is inversely associated with FGF-21 serum levels, a purified and well characterised oligopeptide is able to induce FGF-21 serum levels in humans. These findings suggest a differential role of various components of protein metabolism on FGF-21, rather than this factor being solely a sensor of total nutritional protein intake.

Circulating sDPP-4 is Increased in Obesity and Insulin Resistance but Is Not Related to Systemic Metabolic Inflammation.

CONTEXT: Dipeptidylpeptidase (DPP)-4 is a key regulator of the incretin system. It exists in a membrane-bound form and a soluble form (sDPP-4). Initial human studies suggested sDPP-4 to be an adipokine involved in metabolic inflammation. However, recent mechanistic data in genetically modified mice has questioned these findings. OBJECTIVES: We examined circulating sDPP-4 in a cohort of n = 451 humans with different metabolic phenotypes and during 3 different weight loss interventions (n = 101) to further clarify its role in human physiology and metabolic diseases. DESIGN: sDPP-4 serum concentrations were measured by enzyme-linked immunosorbent assay and related to several phenotyping data including gut microbiome analysis. RESULTS: sDPP-4 increased with age and body weight and was positively associated with insulin resistance and hypertriglyceridemia but was reduced in manifest type 2 diabetes. In addition, we found reduced serum concentrations of sDPP-4 in subjects with arterial hypertension. In contrast to earlier reports, we did not identify an association with systemic markers of inflammation. Impaired kidney and liver functions significantly altered sDPP-4 concentrations while no relation to biomarkers for heart failure was observed. Having found increased levels of sDPP-4 in obesity, we studied surgical (gastric bypass and sleeve gastrectomy) and nonsurgical interventions, revealing a significant association of sDPP-4 with improvement of liver function tests but not with changes in body weight. CONCLUSIONS: Our data suggest that sDPP-4 is related to hepatic abnormalities in obesity rather than primarily functioning as an adipokine and that sDPP-4 is implicated both in glucose and in lipid metabolism, but not fundamentally in systemic inflammation.

Role of wnt5a in Metabolic Inflammation in Humans.

Context: Common nutrition-associated diseases like obesity and type 2 diabetes are linked to chronic low-grade inflammation. The secreted glycopeptide wingless-type mouse mammary tumor virus integration site family member 5a (wnt5a) has been implicated in metabolic inflammation in rodent models, suggesting a potential treatment target. Data on the role of wnt5a in human physiology have yielded conflicting results. Objective: Serum concentrations of wnt5a were measured in a cross-sectional cohort of 896 people to gain deeper insights into wnt5a physiology. Design: Serum concentrations of wnt5a were measured by ELISA and related to several phenotyping and genotyping data. In vitro experiments were performed in THP-1 macrophages to examine potential molecular mechanisms. Results: Wnt5a levels were significantly positively correlated to IL-6 and triglyceride levels. In subjects with diabetes, wnt5a levels were elevated and significantly correlated with fasting plasma glucose concentrations. Although wnt5a levels were not influenced by common single-nucleotide polymorphisms in the human wnt5a gene, environmental factors significantly altered wnt5a concentrations, as follows: (1) wnt5a levels were reduced in subjects with high nutritional load of the long-chain eicosatetraenoic acid independent of the total caloric intake and overall composition of the macronutrients, and (2) wnt5a levels were lower in humans with a high gut microbiome α diversity. In vitro experiments revealed that stimulation of the IL-6 receptor or the long-chain fatty acid receptor GPR40 directly affected wnt5a expression in human macrophages. Conclusion: Our data suggest that wnt5a is important in linking inflammation to metabolism. The nutrition and the microbiome might be interesting targets to prevent and/or treat wnt5a-mediated metabolic inflammation.

Targeted Microbiome Intervention by Microencapsulated Delayed-Release Niacin Beneficially Affects Insulin Sensitivity in Humans.

OBJECTIVE: Gut microbiota represent a potential novel target for future prediabetes and type 2 diabetes therapies. In that respect, niacin has been shown to beneficially affect the host-microbiome interaction in rodent models. RESEARCH DESIGN AND METHODS: We characterized more than 500 human subjects with different metabolic phenotypes regarding their niacin (nicotinic acid [NA] and nicotinamide [NAM]) status and their gut microbiome. In addition, NA and NAM delayed-release microcapsules were engineered and examined in vitro and in vivo in two human intervention studies (bioavailability study and proof-of-concept/safety study). RESULTS: We found a reduced α-diversity and Bacteroidetes abundance in the microbiome of obese human subjects associated with a low dietary niacin intake. We therefore developed delayed-release microcapsules targeting the ileocolonic region to deliver increasing amounts of NA and NAM to the microbiome while preventing systemic resorption to avoid negative side effects (e.g., facial flushing). In vitro studies on these delayed-release microcapsules revealed stable conditions at pH 1.4, 4.5, and 6.8, followed by release of the compounds at pH 7.4, simulating the ileocolonic region. In humans in vivo, gut-targeted delayed-release NA but not NAM produced a significant increase in the abundance of Bacteroidetes. In the absence of systemic side effects, these favorable microbiome changes induced by microencapsulated delayed-release NA were associated with an improvement of biomarkers for systemic insulin sensitivity and metabolic inflammation. CONCLUSION: Targeted microbiome intervention by delayed-release NA might represent a future therapeutic option for prediabetes and type 2 diabetes.

Hypothalamic Inflammation in Human Obesity Is Mediated by Environmental and Genetic Factors.

Obesity is associated with hypothalamic inflammation (HI) in animal models. In the current study, we examined the mediobasal hypothalamus (MBH) of 57 obese human subjects and 54 age- and sex- matched nonobese control subjects by MRI and analyzed the T2 hyperintensity as a measure of HI. Obese subjects exhibited T2 hyperintensity in the left but not the right MBH, which was strongly associated with systemic low-grade inflammation. MRS revealed the number of neurons in the left hypothalamic region to be similar in obese versus control subjects, suggesting functional but not structural impairment due to the inflammatory process. To gain mechanistic insights, we performed nutritional analysis and 16S rDNA microbiome sequencing, which showed that high-fat diet induces reduction of Parasutterella sp. in the gut, which is significantly correlated with MBH T2 hyperintensity. In addition to these environmental factors, we found subjects carrying common polymorphisms in the JNK or the MC4R gene to be more susceptible to HI. Finally, in a subgroup analysis, bariatric surgery had no effect on MBH T2 hyperintensity despite inducing significant weight loss and improvement of peripheral insulin sensitivity. In conclusion, obesity in humans is associated with HI and disturbances in the gut-brain axis, which are influenced by both environmental and genetic factors.