Insulin resistance associates with hepatic lobular inflammation in subjects with obesity

Purpose: Obese subjects with nonalcoholic fatty liver disease (NAFLD) are more prone to develop additional metabolic disturbances such as systemic insulin resistance (IR) and type 2 diabetes. NAFLD is defined by hepatic steatosis, lobular inflammation, ballooning and stage of fibrosis, but it is unclear if and which components could contribute to IR. Objective: To assess which histological components of NAFLD associate with IR in subjects with obesity, and if so, to what extent. Methods: This cross-sectional study included 78 obese subjects (mean age 46 +/- 11 years; BMI 42.2 +/- 4.7 kg/m(2)). Glucose levels were analysed by hexokinase method and insulin levels with electrochemiluminescence. Homeostasis model assessment-estimated insulin resistance (HOMA-IR) was calculated. Liver biopsies were evaluated for histological components of NAFLD. Results: A positive association between overall NAFLD Activity Score and HOMA-IR was found (r(s) = 0.259, P = 0.022). As per individual components, lobular inflammation and fibrosis stage were positively associated with HOMA-IR, glucose and insulin levels (P < 0.05), and HOMA-IR was higher in patients with more inflammatory foci or higher stage of fibrosis. These findings were independent of age, BMI, triglyceride levels, diabetes status and sex (all P < 0.043). In a combined model, lobular inflammation, but not fibrosis, remained associated with HOMA-IR. Conclusion: In this group of obese subjects, a major contributing histological component of NAFLD to the relation between NAFLD severity and IR seems to be the grade of hepatic lobular inflammation. Although no causal relationship was assessed, preventing or mitigating this inflammatory response in obesity might be of importance in controlling obesity-related metabolic disturbances

The effects of age and obesity on postprandial dynamics of serum testosterone levels in men

Objective Guidelines recommend using fasting samples to evaluate testosterone (T) levels in men, as free and total T levels decrease postprandially. However, it is not clear whether these dynamics are affected by age or obesity. This could be relevant given the obesity epidemic, ageing population and the barrier for screening which fasting could impose. Design/Participants A total of 43 men underwent a solid mixed meal tolerance test. Serum samples were taken fasting, and at 30, 60 and 120 minutes postprandially. A commercial immunoassay was used to determine sex hormone-binding globulin (SHBG) levels, liquid chromatography coupled to tandem mass spectroscopy for total T concentrations and free T levels were calculated. Results Postprandially, both total and free T were lower at all-time points compared with fasting (all, P < .005). At 60 minutes, maximum mean decreases of 15 +/- 15% and 17 +/- 16% were seen for total and free T levels, respectively. Younger men had greater decreases in both total and free T levels compared with men older than 40 years (all, P < .05). A greater decrease at 30 and 60 minutes postprandially was observed for both total and free T levels in nonobese vs obese men (all, P < .05). Conclusions After a mixed meal, total and free T serum levels decreased whereas SHBG levels did not change. Interestingly, postprandial decreases were less pronounced in men older than 40 years and/or with obesity. Although this study indicates less pronounced decreases in certain men, fasting samples remain a prerequisite for establishing correct diagnosis of male hypogonadism

The adipokine sFRP4 induces insulin resistance and lipogenesis in the liver

Secreted frizzled-related protein (sFRP) 4 is an adipokine with increased expression in white adipose tissue from obese subjects with type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). Yet, it is unknown whether sFRP4 action contributes to the development of these pathologies. Here, we determined whether sFRP4 expression in visceral fat associates with NAFLD and whether it directly interferes with insulin action and lipid and glucose metabolism in primary hepatocytes and myotubes. The association of sFRP4 with clinical measures was investigated in obese men with or without type 2 diabetes and with or without biopsy-proven NAFLD. To determine the impact of sFRP4 on metabolic parameters, primary human myotubes (hSkMC), or primary hepatocytes from metabolic healthy C57B16 and from systemic insulin-resistant mice, i.e. aP2-SREBP-1c, were used. Gene expression of sFRP4 in visceral fat from obese men associated with insulin sensitivity, triglycerides and NAFLD. In C57B16 hepatocytes, sFRP4 disturbed insulin action. Specifically, sFRP4 decreased the abundance of IRS1 and FoxO1 together with impaired insulin-mediated activation of Akt-signalling and glycogen synthesis and a reduced suppression of gluconeogenesis by insulin. Moreover, sFRP4 enhanced insulin-stimulated hepatic de novo lipogenesis (DNL). In hSkMC, sFRP4 induced glycolysis rather than inhibiting insulin signalling. Finally, in hepatocytes from aP2-SREBP-1c mice, sFRP4 potentiates existing insulin resistance. Collectively, we show that sFRP4 interferes with hepatocyte insulin action. Physiologically, sFRP4 promotes DNL in hepatocytes and glycolysis in myotubes. These sFRP4-mediated responses may result in a vicious cycle, in which enhanced rates of DNL and glycolysis aggravate hepatic lipid accumulation and insulin resistance

Endoglycosidase S enables a highly simplified clinical chemistry procedure for direct assessment of serum IgG undergalactosylation in chronic inflammatory disease

Over the past 30 years, it has been firmly established that a wide spectrum of (autoimmune) diseases such as rheumatoid arthritis, Crohn's and lupus, but also other pathologies like alcoholic and non-alcoholic steatohepatitis (ASH and NASH) are driven by chronic inflammation and are hallmarked by a reduced level of serum IgG galactosylation. IgG (under)galactosylation is a promising biomarker to assess disease severity, and monitor and adjust therapy. However, this biomarker has not been implemented in routine clinical chemistry because of a complex analytical procedure that necessitates IgG purification, which is difficult to perform and validate at high throughput. We addressed this issue by using endo-beta-N-acetyl-glucosaminidase from Streptococcus pyogenes (endoS) to specifically release Fc N-glycans in whole serum. The entire assay can be completed in a few hours and only entails adding endoS and labeling the glycans with APTS. Glycans are then readily analyzed through capillary electrophoresis. We demonstrate in two independent patient cohorts that IgG undergalactosylation levels obtained with this assay correlate very well with scores calculated from PNGaseF-released glycans of purified antibodies. Our new assay allows to directly and specifically measure the degree of IgG galactosylation in serum through a fast and completely liquid phase protocol, without the requirement for antibody purification. This should help advancing this biomarker toward clinical implementation

Serum vascular cell adhesion molecule-1 predicts significant liver fibrosis in non-alcoholic fatty liver disease

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and is strongly associated with obesity, dyslipidemia and insulin resistance. NAFLD often presents as simple steatosis (NAFL) but can progress to non-alcoholic steatohepatitis (NASH) and fibrosis. Current non-invasive biomarkers are not tailored to identify significant (>= F2) fibrosis, although recent guidelines recommend a stringent follow-up of this patient population. We and others have reported on the role of pathological angiogenesis in the pathogenesis of NAFLD, highlighting pro-angiogenic factors as potential diagnostic markers. OBJECTIVE: To investigate the applicability of angiogenic and endothelial dysfunction markers as non-invasive diagnostic tools for NASH or NASH-associated fibrosis in obese patients. METHODS: In a prospective cross-sectional study, male patients undergoing bariatric surgery (n = 61) and control patients (n = 35) were recruited. Serum protein levels and visceral adipose tissue gene expression of endothelial dysfunction and angiogenic markers were analyzed by multiplex bead-based assay and quantitative RT-PCR, respectively. For validation, we recruited a second cohort of patients undergoing bariatric surgery (n = 40) and a cohort of NAFLD patients from our outpatient clinic (n = 30). RESULTS: We identified serum vascular cell adhesion molecule-1 (VCAM-1) as an independent predictor for >= F2 fibrosis (median 14.0 vs 8.7 ng ml(-1) in patients with and without significant fibrosis; P<0.0001) with an area under the receiver-operating characteristics (AUROC) curve of 0.80. The cutoff point of 13.2 ng ml(-1) showed a sensitivity of 80% and specificity of 83%. In line with these results, VCAM-1 visceral adipose tissue gene expression was also elevated in patients with fibrosis (P=0.030). In the bariatric surgery and clinical validation cohorts, VCAM-1 displayed similar AUROCs of 0.89 and 0.85, respectively. CONCLUSIONS: VCAM-1 levels are able to accurately predict significant (>= F2) fibrosis in NAFLD patients

Late dumping syndrome or postprandial reactive hypoglycaemic syndrome after bariatric surgery

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Divergent dynamics in systemic and tissue-specific metabolic and inflammatory responses during weight loss in subjects with obesity

Aim: Dysfunction of adipose and muscle tissue associates with obesity-related co-morbidities such as insulin resistance (IR) and inflammation. This study investigates changes in systemic and tissue-specific markers of IR and inflammation after gastric bypass surgery (GBS) in subjects with obesity. Methods: Prospective study, twenty subjects with obesity (50 +/- 10 years, 14 men). Prior to, and six months and one year after GBS, subcutaneous abdominal adipose tissue (SAT), skeletal muscle and fasting serum samples were collected. Serum levels of C-reactive protein (CRP), glucose and insulin were determined using standard laboratory assays and serum IL-6, IL-10 and TNF-alpha levels were determined using ELISA. Tissue mRNA expression of inflammation and insulin/glucose metabolism markers were analyzed using qPCR. Results: After GBS, HOMA-IR, CRP and IL-6 serum levels decreased. In SAT, expression of bone morphogenetic protein 4 (BMP4), IL-6, IL-10 and MCP1 decreased and GLUT4 increased (all p < 0.05). In muscle, expression of BMP4, GLUT4 and IL-6 decreased and of MCP1 and IRS-1 increased (all p < 0.05). Conclusion: Systemic improvements in inflammation and IR after GBS are only partially mirrored by corresponding changes in adipokine and myokine expression patterns. As changes in expression of other markers of inflammation and insulin/glucose metabolism appear less consistent and even divergent between tissues, the inflammatory and IR status at systemic level cannot be extrapolated to the situation in metabolically active tissues

Histologically proven hepatic steatosis associates with lower testosterone levels in men with obesity

Men with obesity often present with low testosterone (T) and sex hormone-binding globulin (SHBG) levels. Several mechanisms for this have been proposed, but as SHBG is secreted by hepatocytes and sex steroids undergo hepatic metabolization, this study investigates whether severity and histological components of nonalcoholic fatty liver disease (NAFLD) are associated with sex steroid levels in obese men. This cross-sectional study included 80 obese men (age: 46 +/- 11 years; body mass index: 42.2 +/- 5.5 kg m-2). Serum levels of total T and estradiol (E2) were measured using liquid chromatography coupled with tandem mass spectroscopy (LC/MS-MS) and SHBG and gonadotropins by immunoassay. Liver biopsies were evaluated using Steatosis, Activity, and Fibrosis scoring. Participants with steatohepatitis had similar median (1stquartile-3rd quartile) total T levels (7.6 [5.0-11.0] nmol l-1 vs 8.2 [7.2-10.9] nmol l-1; P = 0.147), lower calculated free T (cFT) levels (148.9 [122.9-188.8] pmol l-1 vs 199.5 [157.3-237.6] pmol l-1; P = 0.006), and higher free E2/T ratios (10.0 [6.4-13.9] x10-3 vs 7.1 [5.7-10.7] x10-3