Liver Fat and Insulin Sensitivity Define Metabolite Profiles During a Glucose Tolerance Test in Young Adult Twins

Characterizing human postprandial metabolic response using multiway data analysis

INTRODUCTION

Analysis of time-resolved postprandial metabolomics data can improve our understanding of the human metabolism by revealing similarities and differences in postprandial responses of individuals. Traditional data analysis methods often rely on data summaries or univariate approaches focusing on one metabolite at a time.

OBJECTIVES

Our goal is to provide a comprehensive picture in terms of the changes in the human metabolism in response to a meal challenge test, by revealing static and dynamic markers of phenotypes, i.e., subject stratifications, related clusters of metabolites, and their temporal profiles.

METHODS

We analyze Nuclear Magnetic Resonance (NMR) spectroscopy measurements of plasma samples collected during a meal challenge test from 299 individuals from the COPSAC2000 cohort using a Nightingale NMR panel at the fasting and postprandial states (15, 30, 60, 90, 120, 150, 240 min). We investigate the postprandial dynamics of the metabolism as reflected in the dynamic behaviour of the measured metabolites. The data is arranged as a three-way array: subjects by metabolites by time. We analyze the fasting state data to reveal static patterns of subject group differences using principal component analysis (PCA), and fasting state-corrected postprandial data using the CANDECOMP/PARAFAC (CP) tensor factorization to reveal dynamic markers of group differences.

RESULTS

Our analysis reveals dynamic markers consisting of certain metabolite groups and their temporal profiles showing differences among males according to their body mass index (BMI) in response to the meal challenge. We also show that certain lipoproteins relate to the group difference differently in the fasting vs. dynamic state. Furthermore, while similar dynamic patterns are observed in males and females, the BMI-related group difference is observed only in males in the dynamic state.

CONCLUSION

The CP model is an effective approach to analyze time-resolved postprandial metabolomics data, and provides a compact but a comprehensive summary of the postprandial data revealing replicable and interpretable dynamic markers crucial to advance our understanding of changes in the metabolism in response to a meal challenge.

Untargeted Metabolomics Based on Liquid Chromatography-Mass Spectrometry for the Analysis of Plasma and Erythrocyte Samples in Childhood Obesity

The circulating metabolome of human peripheral blood provides valuable information to investigate the molecular mechanisms underlying the development of diseases and to discover candidate biomarkers. In particular, erythrocytes have been proposed as potential systemic indicators of the metabolic and redox status of the organism. To accomplish wide-coverage metabolomics analysis, the combination of complementary analytical techniques is necessary to manage the physicochemical complexity of the human metabolome. Herein, we describe an untargeted metabolomics method to capture the plasmatic and erythroid metabolomes based on ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry, combining reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography. The method provides comprehensive metabolomics fingerprinting of plasma and erythrocyte samples, thereby enabling the elucidation of the distinctive metabolic disturbances behind childhood obesity and associated comorbidities, such as insulin resistance.

Dynamic patterns of postprandial metabolic responses to three dietary challenges

Food intake triggers extensive changes in the blood metabolome. The kinetics of these changes depend on meal composition and on intrinsic, health-related characteristics of each individual, making the assessment of changes in the postprandial metabolome an opportunity to assess someone's metabolic status. To enable the usage of dietary challenges as diagnostic tools, profound knowledge about changes that occur in the postprandial period in healthy individuals is needed. In this study, we characterize the time-resolved changes in plasma levels of 634 metabolites in response to an oral glucose tolerance test (OGTT), an oral lipid tolerance test (OLTT), and a mixed meal (SLD) in healthy young males (n = 15). Metabolite levels for samples taken at different time points (20 per individual) during the challenges were available from targeted (132 metabolites) and non-targeted (502 metabolites) metabolomics. Almost half of the profiled metabolites (n = 308) showed a significant change in at least one challenge, thereof 111 metabolites responded exclusively to one particular challenge. Examples include azelate, which is linked to ω-oxidation and increased only in OLTT, and a fibrinogen cleavage peptide that has been linked to a higher risk of cardiovascular events in diabetes patients and increased only in OGTT, making its postprandial dynamics a potential target for risk management. A pool of 89 metabolites changed their plasma levels during all three challenges and represents the core postprandial response to food intake regardless of macronutrient composition. We used fuzzy c-means clustering to group these metabolites into eight clusters based on commonalities of their dynamic response patterns, with each cluster following one of four primary response patterns: (i) “decrease-increase” (valley-like) with fatty acids and acylcarnitines indicating the suppression of lipolysis, (ii) “increase-decrease” (mountain-like) including a cluster of conjugated bile acids and the glucose/insulin cluster, (iii) “steady decrease” with metabolites reflecting a carryover from meals prior to the study, and (iv) “mixed” decreasing after the glucose challenge and increasing otherwise. Despite the small number of subjects, the diversity of the challenges and the wealth of metabolomic data make this study an important step toward the characterization of postprandial responses and the identification of markers of metabolic processes regulated by food intake.

Investigating the Postprandial Metabolome after Challenge Tests to Assess Metabolic Flexibility and Dysregulations Associated with Cardiometabolic Diseases

This review focuses on the added value provided by a research strategy applying metabolomics analyses to assess phenotypic flexibility in response to different nutritional challenge tests in the framework of metabolic clinical studies. We discuss findings related to the Oral Glucose Tolerance Test (OGTT) and to mixed meals with varying fat contents and food matrix complexities. Overall, the use of challenge tests combined with metabolomics revealed subtle metabolic dysregulations exacerbated during the postprandial period when comparing healthy and at cardiometabolic risk subjects. In healthy subjects, consistent postprandial metabolic shifts driven by insulin action were reported (e.g., a switch from lipid to glucose oxidation for energy fueling) with similarities between OGTT and mixed meals, especially during the first hours following meal ingestion while differences appeared in a wider timeframe. In populations with expected reduced phenotypic flexibility, often associated with increased cardiometabolic risk, a blunted response on most key postprandial pathways was reported. We also discuss the most suitable statistical tools to analyze the dynamic alterations of the postprandial metabolome while accounting for complexity in study designs and data structure. Overall, the in-depth characterization of the postprandial metabolism and associated phenotypic flexibility appears highly promising for a better understanding of the onset of cardiometabolic diseases.

The Association Between Fecal Short-Chain Fatty Acids, Gut Microbiota, and Visceral Fat in Monozygotic Twin Pairs

PURPOSE

To examine the association of short-chain fatty acids (SCFAs), gut microbiota and obesity in individual twins and to control for genetic and shared environmental effects by studying monozygotic intrapair differences.

PATIENTS AND METHODS

The study recruited 20 pairs of monozygotic twins. Body composition measurements were performed by using the multi-frequency bioelectrical impedance technique. SCFAs were extracted from feces and quantified by gas chromatography-mass spectrometer. Gut microbiota was evaluated by 16S rRNA gene sequencing.

RESULTS

Fecal SCFAs were negatively correlated with adiposity parameters including body mass index, visceral adipose tissue and waist circumference (all P < 0.05). Metastat analysis showed that the top 5 relatively abundant bacterial taxa of viscerally obese and non-obese groups were Bacteroides, Collinsella, Eubacterium rectale group, Lachnoclostridium, and Tyzzerella. Participants with visceral obesity had lower abundance of Bacteroides and Collinsella compared to non-obese patients (P < 0.05). Among them, the abundance of Collinsella was positively correlated with acetic acid concentrations (r = 0.63, P = 0.011). There were no significant intrapair differences in each SCFA concentrations between the twins in our study (P > 0.05).

CONCLUSION

Low fecal concentrations of SCFAs were associated with visceral obesity, and the gut microbiota might be involved in the underlying mechanism.

Comparison of pancreatic function and quality of life between patients with infected pancreatitis necrosis undergoing open necrosectomy and minimally invasive drainage: A long-term study

The present study aimed to determine whether a difference in pancreatic function and quality of life (QoL) is present between patients with infected pancreatitis necrosis (IPN) undergoing open necrosectomy (ON) and minimally invasive drainage (MID). The medical records of patients with IPN discharged from Jinling Hospital were retrospectively analyzed. Pancreatic function and QoL were compared between patients treated with ON and MID. Pancreatic endocrine and exocrine function were assessed using the oral glucose tolerance test and fecal elastase-1 (FE-1) test, respectively. The standard Short Form 36 health questionnaire was used to evaluate the QoL of patients. The analysis included 101 patients who underwent either ON (n=40, 39.6%) or MID (n=61, 60.4%). There were no significant differences in exocrine and endocrine pancreatic function between the two groups evaluated based on FE-1, fasting blood glucose, glycated hemoglobin and 2-h plasma glucose (P<0.05). The scores of the QoL questionnaire were significantly higher in patients treated with MID than in patients treated with ON, including the scores of general health perception (19.39±3.07 vs. 17.37±3.63, P=0.003), vitality (18.93±2.88 vs. 17.57±3.47, P=0.035), social role functioning (8.85±1.43 vs. 8.15±1.98, P=0.042), emotional role functioning (5.33±1.07 vs. 4.82±1.25, P=0.034), mental health (24.21±3.31 vs. 22.57±3.91, P=0.026) and the total QoL score (125.12±13.16 vs. 116.50±16.94, P=0.005). In conclusion, although the initial health of the patient may have influenced the treatment provided, patients with IPN who received MID achieved a better post-treatment QoL than those treated with ON. No significant differences between the two groups were observed regarding the endocrine and exocrine functions of the pancreas.

Insulin resistance and systemic metabolic changes in oral glucose tolerance test in 5340 individuals: an interventional study

BACKGROUND

Insulin resistance (IR) is predictive for type 2 diabetes and associated with various metabolic abnormalities in fasting conditions. However, limited data are available on how IR affects metabolic responses in a non-fasting setting, yet this is the state people are mostly exposed to during waking hours in the modern society. Here, we aim to comprehensively characterise the metabolic changes in response to an oral glucose test (OGTT) and assess the associations of these changes with IR.

METHODS

Blood samples were obtained at 0 (fasting baseline, right before glucose ingestion), 30, 60, and 120 min during the OGTT. Seventy-eight metabolic measures were analysed at each time point for a discovery cohort of 4745 middle-aged Finnish individuals and a replication cohort of 595 senior Finnish participants. We assessed the metabolic changes in response to glucose ingestion (percentage change in relative to fasting baseline) across the four time points and further compared the response profile between five groups with different levels of IR and glucose intolerance. Further, the differences were tested for covariate adjustment, including gender, body mass index, systolic blood pressure, fasting, and 2-h glucose levels. The groups were defined as insulin sensitive with normal glucose (IS-NGT), insulin resistant with normal glucose (IR-NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and new diabetes (NDM). IS-NGT and IR-NGT were defined as the first and fourth quartile of fasting insulin in NGT individuals.

RESULTS

Glucose ingestion induced multiple metabolic responses, including increased glycolysis intermediates and decreased branched-chain amino acids, ketone bodies, glycerol, and triglycerides. The IR-NGT subgroup showed smaller responses for these measures (mean + 23%, interquartile 9-34% at 120 min) compared to IS-NGT (34%, 23-44%, P < 0.0006 for difference, corrected for multiple testing). Notably, the three groups with glucose abnormality (IFG, IGT, and NDM) showed similar metabolic dysregulations as those of IR-NGT. The difference between the IS-NGT and the other subgroups was largely explained by fasting insulin, but not fasting or 2 h glucose. The findings were consistent after covariate adjustment and between the discovery and replication cohort.

CONCLUSIONS

Insulin-resistant non-diabetic individuals are exposed to a similar adverse postprandial metabolic milieu, and analogous cardiometabolic risk, as those with type 2 diabetes. The wide range of metabolic abnormalities associated with IR highlights the necessity of diabetes diagnostics and clinical care beyond glucose management.

Effect of the disease severity on the risk of developing new-onset diabetes after acute pancreatitis

Endocrine pancreatic insufficiency secondary to acute pancreatitis (AP) drew increasing attention in the recent years. The aim of the present study was to assess the impact of pancreatic necrosis and organ failure on the risk of developing new-onset diabetes after AP.The follow-up study was conducted for patients recovered from AP in the treatment center of Jinling Hospital. Endocrine function was evaluated by simplified oral glucose tolerance test (OGTT). Pancreatic necrosis was examined by abdominal contrast-enhanced CT (CECT) scan during hospitalization. The data including APACHE II score, Balthazar's score, organ failure (AKI and ARDS) was also collected from the medical record database. All patients were divided into group diabetes mellitus (DM) and group non-DM according to the endocrine function and group pancreatic necrosis (PN) and persistent organ failure (OF), group PN and non-OF, group non-PN and OF, and group non-PN and non-OF according to the occurrence of pancreatic necrosis and persistent organ failure.Around 256 patients were included for the final analysis. 154 patients (60.2%) were diagnosed with DM (include impaired glucose tolerance, IGT), while 102 patients (39.8%) were deemed as normal endocrine function. APACHE II score and Balthazar score of the patients in the group DM were significant higher than those in the non-DM group (F = 6.09, P = .01; F = 10.74, P = .001). The incidence of pancreatic necrosis in group DM and group non-DM was, respectively, 64.7% and 53.0% (χ = 3.506, P = .06). The patients underwent necrosis debridement by percutaneous catheter drainage (PCD) and/or the operative necrosectomy (ON) were more likely to developed new onset DM than the patients without PCD or ON (χ = 2.385, P = .02). The morbidity of new-onset DM after AP gradually increased from group non-PN and non-OF, group non-PN and OF, group PN and non-OF to group PN and OF in order (χ = 4.587, P = .03). The value of HOMA-IR of patients at follow-up time was significant higher in group DM than group non-DM (F = 13.414, P = .000).Patients with both PN and persistent OF may were at increased risk of developing new-onset diabetes after AP. Insulin resistance could be the pivotal mechanism of the development of diabetes.

Adipose tissue and liver

Adipose tissue and liver are central tissues in whole body energy metabolism. Their composition, structure, and function can be noninvasively imaged using a variety of measurement techniques that provide a safe alternative to an invasive biopsy. Imaging of adipose tissue is focused on quantitating the distribution of adipose tissue in subcutaneous and intra-abdominal (visceral) adipose tissue depots. Also, detailed subdivisions of adipose tissue can be distinguished with modern imaging techniques. Adipose tissue (or adipocyte) accumulation or infiltration of other organs can also be imaged, with intramuscular adipose tissue a common example. Although liver fat content is now accurately imaged using standard magnetic resonance imaging (MRI) techniques, inflammation and fibrosis are more difficult to determine noninvasively. Liver imaging efforts are therefore concerted on developing accurate imaging markers of liver fibrosis and inflammatory status. Magnetic resonance elastography (MRE) is presently the most reliable imaging technique for measuring liver fibrosis but requires an external device for introduction of shear waves to the liver. Methods using multiparametric diffusion, perfusion, relaxometry, and hepatocyte-specific MRI contrast agents may prove to be more easily implemented by clinicians, provided they reach similar accuracy as MRE. Adipose tissue imaging is experiencing a revolution with renewed interest in characterizing and identifying distinct adipose depots, among them brown adipose tissue. Magnetic resonance spectroscopy provides an interesting yet underutilized way of imaging adipose tissue metabolism through its fatty acid composition. Further studies may shed light on the role of fatty acid composition in different depots and why saturated fat in subcutaneous adipose tissue is a marker of high insulin sensitivity.

Endocrine and exocrine pancreatic insufficiency after acute pancreatitis: long-term follow-up study

BACKGROUND

Patients could develop endocrine and exocrine pancreatic insufficiency after acute pancreatitis (AP), but the morbidity, risk factors and outcome remain unclear. The aim of the present study was to evaluate the incidence of endocrine and exocrine pancreatic insufficiency after AP and the risk factors of endocrine pancreatic insufficiency through a long-term follow-up investigation.

METHODS

Follow-up assessment of the endocrine and exocrine function was conducted for the discharged patients with AP episodes. Oral Glucose Tolerance Test (OGTT) and faecal elastase-1(FE-1) test were used as primary parameters. Fasting blood-glucose (FBG), fasting insulin (FINS), glycosylated hemoglobin HBA1c, 2-h postprandial blood glucose (2hPG), Homa beta cell function index (HOMA-β), homeostasis model assessment of insulin resistance (HOMA-IR) and FE-1 were collected. Abdominal contrast-enhanced computed tomography (CECT) was performed to investigate the pancreatic morphology and the other related data during hospitalization was also collected.

RESULTS

One hundred thirteen patients were included in this study and 34 of whom (30.1%) developed diabetes mellitus (DM), 33 (29.2%) suffered impaired glucose tolerance (IGT). Moreover, 33 patients (29.2%) developed mild to moderate exocrine pancreatic insufficiency with 100μg/g

CONCLUSION

The integrated morbidity of DM and IGT after AP was 59.25%, which was higher than exocrine pancreatic insufficiency. 6.2% and 29.2% of patients developed severe and mild to moderate exocrine pancreatic insufficiency, respectively. The extent of pancreatic necrosis>50%, WON and insulin resistance were the independent risk factors of new onset diabetes after AP.

Collapse

Key Words

• Acute pancreatitis
• Endocrine pancreatic insufficiency
• Exocrine pancreatic insufficiency
• Follow-up study
• Insulin resistance
• Pancreatic necrosis

Collapse

MESH Headings

• Acute Disease
• Diabetes Complications
• Exocrine Pancreatic Insufficiency/etiology
• Female
• Follow-Up Studies
• Glucose Intolerance/complications
• Humans
• Male
• Middle Aged
• Pancreatitis/complications
• Regression Analysis
• Risk Factors

Collapse

Grants

• National Natural Science Foundation of China
• Science and Technology Foundation of Zhejiang Province

Collapse

Affiliation(s)

Jianfeng Tu Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Shangtang road 158#, Hangzhou, 310014 China
Jingzhu Zhang Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Lu Ke Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Yue Yang Hangzhou Medical College, Binwen road 481#, Hangzhou, 310053 China
Qi Yang Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Guotao Lu Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Baiqiang Li Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Zhihui Tong Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Weiqin Li Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China
Jieshou Li Research Institute of General Surgery, Jinling Hospital, Medical School of Nanjing University, 305 East Zhongshan Road, Nanjing, 210002 China

Collapse