IL-6 Trans-Signaling Is Increased in Diabetes, Impacted by Glucolipotoxicity, and Associated With Liver Stiffness and Fibrosis in Fatty Liver Disease

Many people living with diabetes also have nonalcoholic fatty liver disease (NAFLD). Interleukin-6 (IL-6) is involved in both diseases, interacting with both membrane-bound (classical) and circulating (trans-signaling) soluble receptors. We investigated whether secretion of IL-6 trans-signaling coreceptors are altered in NAFLD by diabetes and whether this might associate with the severity of fatty liver disease. Secretion patterns were investigated with use of human hepatocyte, stellate, and monocyte cell lines. Associations with liver pathology were investigated in two patient cohorts: 1) biopsy-confirmed steatohepatitis and 2) class 3 obesity. We found that exposure of stellate cells to high glucose and palmitate increased IL-6 and soluble gp130 (sgp130) secretion. In line with this, plasma sgp130 in both patient cohorts positively correlated with HbA1c, and subjects with diabetes had higher circulating levels of IL-6 and trans-signaling coreceptors. Plasma sgp130 strongly correlated with liver stiffness and was significantly increased in subjects with F4 fibrosis stage. Monocyte activation was associated with reduced sIL-6R secretion. These data suggest that hyperglycemia and hyperlipidemia can directly impact IL-6 trans-signaling and that this may be linked to enhanced severity of NAFLD in patients with concomitant diabetes.

ARTICLE HIGHLIGHTS

IL-6 and its circulating coreceptor sgp130 are increased in people with fatty liver disease and steatohepatitis. High glucose and lipids stimulated IL-6 and sgp130 secretion from hepatic stellate cells. sgp130 levels correlated with HbA1c, and diabetes concurrent with steatohepatitis further increased circulating levels of all IL-6 trans-signaling mediators. Circulating sgp130 positively correlated with liver stiffness and hepatic fibrosis. Metabolic stress to liver associated with fatty liver disease might shift the balance of IL-6 classical versus trans-signaling, promoting liver fibrosis that is accelerated by diabetes.

Preoperative predictors of type 2 diabetes remission after bilio-pancreatic diversion with duodenal switch

BACKGROUND

Many patients achieve short-term type 2 diabetes (T2D) remission after bariatric surgery, but relapses are common. Diabetes outcomes after bariatric surgery vary across procedures and populations. T2D remission scores are simple clinical tools developed to predict remission after bariatric surgery. However, they have never been tested after Biliopancreatic diversion with duodenal switch (BPD-DS).

OBJECTIVES

The aim of this study was to compare the predictive value of T2D remission scores and preoperative diabetes characteristics in predicting T2D remission after BPD-DS.

SETTING

Quebec Heart and Lung Institute - Laval University.

METHODS

We retrospectively identified 918 patients with preoperative T2D who had undergone BPD-DS. Retrospective chart review was performed and variables used to calculate predictive scores were captured. T2D status was assessed annually for up to 10 years postop. Predictive values for each score (DiarRem, Ad Diarem, and Diabetter) and single preoperative diabetes characteristics used to construct these algorithms were evaluated by area under receiver operating characteristic curves (AUC).

RESULTS

Diabetter showed greater performance for prediction of durable diabetes remission than other algorithms with acceptable discriminative ability (AUC between .69 and .79), but was not superior to T2D duration as a single predictor (P = .24 and P = .18). At 10 years, T2D duration had a better discriminative ability for the prediction of T2D remission than all 3 predictive models (AUC = .85, P < .05).

CONCLUSIONS

Better chances for T2D remission following BPD-DS are associated with a shorter duration or T2D before surgery. Duration of T2D alone offers an excellent predictive ability and is a convenient alternative to diabetes remission scores to estimate chances of long-term diabetes remission after BPD-DS.

Adipocyte Size, Adipose Tissue Fibrosis, Macrophage Infiltration and Disease Risk Are Different in Younger and Older Individuals with Childhood and Adulthood Onset Obesity

Objectives

The timing of obesity onset and age have been shown to affect the risk of obesity-related comorbidities, although the impact of each of these factors on markers of adipose tissue function remains unclear. The aim of this study is to determine whether differences in regional adipose tissue characteristics vary with age and age of obesity onset, and whether these differences are associated with the markers of cardiometabolic health.

Methods

Adipose tissue samples were from 80 female bariatric surgery candidates who were classified by age of obesity onset and age into 4 groups: 1) younger adults (<40 y) with childhood-onset obesity (< 18 y) (Childhood-Young); 2) younger adults with adulthood-onset obesity (>18 y) (Adulthood-Young); 3) older adults (>55 y) with childhood-onset obesity (Childhood-Old); and 4) older adults with adulthood-onset obesity (Adulthood-Old). Adipocyte diameter, adipose tissue fibrosis and macrophage infiltration were determined in subcutaneous (SAT) and visceral adipose tissue (VAT). Clinical parameters were obtained from participants’ medical records.

Results

Visceral adipocyte size in the Childhood-Young group was the smallest of all the groups. Age affected visceral infiltration of M1-like cells in both older groups, whereas onset, specifically childhood-onset, was related to visceral infiltration of M2-like cells in the Childhood-Old group. Fibrosis accumulation in SAT and VAT varied with age and onset, particularly in the Childhood-Old group having the lowest fibrosis levels. Markers of cardiometabolic health (fasting glucose, glycated hemoglobin, total, HDL- and LDL-cholesterol and triglyceride concentrations) were positively and well associated with adipose tissue characteristics of the Childhood-Old group but not of the Adulthood-Young group.

Conclusions

Older adults with childhood onset obesity, who had the greatest duration of obesity exposure, were particularly vulnerable to the cardiometabolic effects associated with perturbations in adipose tissue characteristics. These results, suggest that age and age of obesity onset may have independent and cumulative effects on obesity pathology.

Funding Sources

Sylvia Santosa holds a Canada Research Chair – Tier 2 in Clinical Nutrition. This research is also supported by a Discovery Grant from The Natural Science and Engineering Research Council of Canada.

Spontaneous neural activity changes after bariatric surgery: A resting-state fMRI study

BACKGROUND

Metabolic disorders associated with obesity could lead to alterations in brain structure and function. Whether these changes can be reversed after weight loss is unclear. Bariatric surgery provides a unique opportunity to address these questions because it induces marked weight loss and metabolic improvements which in turn may impact the brain in a longitudinal fashion. Previous studies found widespread changes in grey matter (GM) and white matter (WM) after bariatric surgery. However, findings regarding changes in spontaneous neural activity following surgery, as assessed with the fractional amplitude of low frequency fluctuations (fALFF) and regional homogeneity of neural activity (ReHo), are scarce and heterogenous. In this study, we used a longitudinal design to examine the changes in spontaneous neural activity after bariatric surgery (comparing pre- to post-surgery), and to determine whether these changes are related to cardiometabolic variables.

METHODS

The study included 57 participants with severe obesity (mean BMI=43.1 ± 4.3 kg/m²) who underwent sleeve gastrectomy (SG), biliopancreatic diversion with duodenal switch (BPD), or Roux-en-Y gastric bypass (RYGB), scanned prior to bariatric surgery and at follow-up visits of 4 months (N = 36), 12 months (N = 29), and 24 months (N = 14) after surgery. We examined fALFF and ReHo measures across 1022 cortical and subcortical regions (based on combined Schaeffer-Xiao parcellations) using a linear mixed effect model. Voxel-based morphometry (VBM) based on T1-weighted images was also used to measure GM density in the same regions. We also used an independent sample from the Human Connectome Project (HCP) to assess regional differences between individuals who had normal-weight (N = 46) or severe obesity (N = 46).

RESULTS

We found a global increase in the fALFF signal with greater increase within dorsolateral prefrontal cortex, precuneus, inferior temporal gyrus, and visual cortex. This effect was more significant 4 months after surgery. The increase within dorsolateral prefrontal cortex, temporal gyrus, and visual cortex was more limited after 12 months and only present in the visual cortex after 24 months. These increases in neural activity measured by fALFF were also significantly associated with the increase in GM density following surgery. Furthermore, the increase in neural activity was significantly related to post-surgery weight loss and improvement in cardiometabolic variables, such as blood pressure. In the independent HCP sample, normal-weight participants had higher global and regional fALFF signals, mainly in dorsolateral/medial frontal cortex, precuneus and middle/inferior temporal gyrus compared to the obese participants. These BMI-related differences in fALFF were associated with the increase in fALFF 4 months post-surgery especially in regions involved in control, default mode and dorsal attention networks.

CONCLUSIONS

Bariatric surgery-induced weight loss and improvement in metabolic factors are associated with widespread global and regional increases in neural activity, as measured by fALFF signal. These findings alongside the higher fALFF signal in normal-weight participants compared to participants with severe obesity in an independent dataset suggest an early recovery in the neural activity signal level after the surgery.

THE METAL-CATALYZED AUTOXIDATION OF TETRALIN: II. THE COBALT-CATALYZED AUTOXIDATION OF UNDILUTED TETRALIN AND OF TETRALIN IN CHLOROBENZENE

The catalysis of the autoxidation of tetralin by the cobalt salts of 10 organic acids has been examined at 50 °C over a concentration range from 2 × 10−6to 1.0 mole/l, of cobalt. The measured rate of oxidation reaches a limiting value at cobalt concentrations above 2 × 10−2mole/l., which is about half the expected limiting rate. The cobalt salt catalysts are deactivated during the oxidation, probably in the initiation reaction with hydroperoxide, each cobalt atom being capable of decomposing about 100 molecules of hydroperoxide. Upon correcting the measured limiting rate for cobalt deactivation and for the amount of tetralin consumed at the point where the rate reaches a maximum value an extrapolated limiting rate about equal to the expected value is obtained. Although no steady concentration of hydroperoxide occurs during the oxidation the results suggest that the limiting rate of oxidation is basically due to the same phenomena that produce a limiting rate for the cobalt-catalyzed autoxidation of tetralin in acetic acid (Y. Kamiya et al. Can. J. Chem. 41, 2020 (1963)).

THE METAL-CATALYZED AUTOXIDATION OF TETRALIN: I. INTRODUCTION. THE COBALT-CATALYZED AUTOXIDATION IN ACETIC ACID

The catalytic effect of transition metal salts on the rate of autoxidation of organic substances reaches a constant value at some critical catalyst concentration. Three possible explanations of this phenomena are critically examined. The cobalt acetate catalyzed autoxidation of tetralin in acetic acid has been reinvestigated and the limiting rate of oxidation at high cobalt concentrations has been shown to be due to the production of a steady-state concentration of hydroperoxide. The present results are in fair agreement with the experimental work of Woodward and Mesrobian (J. Am. Chem. Soc. 75, 6189 (1953)) and are in excellent agreement with theoretical predictions.