The prevalence of obesity has reached epidemic proportions and keeps growing. Obesity seems implicated in the pathogenesis of cognitive dysfunction, Alzheimer’s disease and dementia, and vice versa. Growing scientific efforts are being devoted to the identification of central mechanisms underlying the frequent association between obesity and cognitive dysfunction. Glucose brain handling undergoes dynamic changes during the life-course, suggesting that its alterations might precede and contribute to degenerative changes or signaling abnormalities. Imaging of the glucose analog 18F-labeled fluorodeoxyglucose (18FDG) by positron emission tomography (PET) is the gold-standard for the assessment of cerebral glucose metabolism in vivo. This review summarizes the current literature addressing brain glucose uptake measured by PET imaging, and the effect of insulin on brain metabolism, trying to embrace a life-course vision in the identification of patterns that may explain (and contribute to) the frequent association between obesity and cognitive dysfunction. The current evidence supports that brain hypermetabolism and brain insulin resistance occur in selected high-risk conditions as a transient phenomenon, eventually evolving toward normal or low values during life or disease progression. Associative studies suggest that brain hypermetabolism predicts low BDNF levels, hepatic and whole body insulin resistance, food desire and an unfavorable balance between anticipated reward from food and cognitive inhibitory control. Emerging mechanistic links involve the microbiota and the metabolome, which correlate with brain metabolism and cognition, deserving attention as potential future prevention targets.
Patricia Iozzo and Maria Angela Guzzardi
Richard H Tuligenga
The aim of this meta-analysis was to compare the effect of intensive vs standard glycaemic control on cognitive decline in type 2 diabetic patients. A systematic search of PubMed and ALOIS was conducted from inception up to October 30, 2014. Randomised controlled trials (RCTs) of type 2 diabetic patients comparing the rate of change in cognitive function among participants assigned to intensive vs standard glycaemic control were included. An inverse-variance-weighted random effects model was used to calculate standardised mean differences (SMDs) and 95% CIs. A total of 24 297 patients from five RCTs were included in the meta-analysis. Follow-up ranged from 3.3 to 6.2 years. The result from the pooled analysis showed that intensive glycaemic control was not associated with a slower rate of cognitive decline in patients with type 2 diabetes, compared with standard glycaemic control (SMD=0.02; 95% CI=−0.03 to 0.08) although there was some heterogeneity across individual studies (I 2=68%, P for heterogeneity=0.01). There are few diabetes control trials including cognitive endpoints and a small number of trials comparing intensive and standard treatment strategies. Currently, intensive glycaemic control should not be recommended for prevention of cognitive decline in patients with type 2 diabetes because there is no evidence of its effectiveness. Moreover, the use of intensive diabetes treatment results in an increase of risk of hypoglycaemia, which is linked to a greater risk of poor cognition.
Frederique Van de Velde, Marlies Bekaert, Anja Geerts, Anne Hoorens, Arsène-Hélène Batens, Samyah Shadid, Margriet Ouwens, Yves Van Nieuwenhove and Bruno Lapauw
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.
To assess which histological components of NAFLD associate with IR in subjects with obesity, and if so, to what extent.
This cross-sectional study included 78 obese subjects (mean age 46 ± 11 years; BMI 42.2 ± 4.7 kg/m2). 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.
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.
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.
Charlotte Höybye, Laia Faseh, Christos Himonakos, Tomasz Pielak and Jesper Eugen-Olsen
Growth hormone deficiency (GHD) syndrome is associated with adverse levels of several risk factors for cardiovascular diseases (CVD), including metabolic inflammation. However, the impact of GHD and GH treatment on low-grade inflammation is unknown. The aim of the study was to establish the level of the low-grade inflammation biomarker soluble urokinase plasminogen activator receptor (suPAR) in adults with GHD and the response to long-term GH treatment. Measurements of suPAR and CRP were performed in bio-bank serum samples from 72 adults, 34 males and 38 females, with GHD before and during at least 5 years of GH treatment. Mean age was 52.5 ± 15.5 years, BMI 27.3 ± 5 kg/m2. Clinical evaluations and blood sampling were performed at routine visits. Data on demography, anthropometry, lab results and clinical events were retrieved from post-marketing surveillance study databases and medical records. suPAR and high-sensitive (hs) CRP were analysed using ELISA and immunochemistry, respectively. At baseline blood pressure, lipid profile and fasting glucose were within the normal reference range. Baseline geometric mean and 95% CI of suPAR was 2.9 (2.7–3.3) ng/mL and of CRP 2.3 (0.6–4.0) mg/L. Mean follow-up was 8 ± 2 years. The suPAR levels remained stable during follow-up, although individual increases were seen on occurrence or presence of co-morbidities. In contrast, levels of CRP decreased. In conclusion, the decrease in CRP and indirectly the absence of an expected increase in suPAR over time indicates a favourable effect of GH on low-grade inflammation.
M A Webb, H Mani, S J Robertson, H L Waller, D R Webb, C L Edwardson, D H Bodicoat, T Yates, K Khunti and M J Davies
Physical activity has been proposed to be an effective non-pharmacological method of reducing systemic inflammation and therefore may prove particularly efficacious for women with polycystic ovary syndrome (PCOS) who have been shown to have high levels of inflammation and an increased risk of type 2 diabetes (T2DM) and cardiovascular disease (CVD). Therefore, the aim of the present study was to assess whether modest changes in daily step count could significantly reduce levels of inflammatory markers in women with PCOS.
Subjects and Methods
Sixty-five women with PCOS were assessed at baseline and again at 6 months. All had been provided with an accelerometer and encouraged to increase activity levels. Multivariate linear regression analyses (adjusted for age, ethnicity, baseline step count, change in BMI and change in accelerometer wear-time) were used to assess changes in daily step count against clinical and research biomarkers of inflammation, CVD and T2DM.
Mean step count/day at baseline was 6337 (±270). An increase in step count (by 1000 steps) was associated with a 13% reduction in IL6 (β: −0.81 ng/L; 95% CI, −1.37, −0.25, P = 0.005) and a 13% reduction in CRP (β: −0.68 mg/L; 95% CI, −1.30, −0.06, P = 0.033). Additionally, there was a modest decrease in BMI (β: 0.20 kg/m2; 95% CI, −0.38, −0.01, P = 0.038). Clinical markers of T2DM and CVD were not affected by increased step count.
Modest increases in step count/day can reduce levels of inflammatory markers in women with PCOS, which may reduce the future risk of T2DM and CVD.
Lars Peter Sørensen, Tina Parkner, Esben Søndergaard, Bo Martin Bibby, Holger Jon Møller and Søren Nielsen
Monocyte/macrophage-specific soluble CD163 (sCD163) concentration is associated with insulin resistance and increases with deteriorating glycemic control independently of BMI. This led to the proposal of the hypothesis that obesity-associated white adipose tissue inflammation varies between individuals. The objective was to examine the effect of male overweight/obesity and type 2 diabetes mellitus (T2DM) on associations between adiposity parameters and sCD163. A total of 23 overweight/obese non-diabetic men, 16 overweight/obese men with T2DM, and a control group of 20 normal-weight healthy men were included. Body composition and regional body fat distribution were determined by whole-body dual X-ray absorptiometry scan and abdominal computed tomography (CT) scan. Serum sCD163 concentrations were determined by ELISA. Associations between adiposity parameters and sCD163 were investigated using multiple linear regression analysis. In the normal-weight healthy men, there was no significant association between adiposity parameters and sCD163, whereas in the overweight/obese non-diabetic men, measures of general and regional adiposity were positively associated with sCD163. In the overweight/obese men with T2DM, only visceral adipose tissue (VAT) and the ratio of VAT to abdominal subcutaneous adipose tissue (SAT), a measure of relative body fat distribution between VAT and SAT depots, were positively associated with sCD163. In a multivariate analysis, including VAT, upper-body SAT, and lower-body fat, adjusted for BMI and age, VAT remained a significant predictor of sCD163 in the overweight/obese T2DM men, but not in the overweight/obese non-diabetic men. Our results indicate that VAT inflammation is exaggerated in men with T2DM, and that propensity to store excess body fat viscerally is particularly detrimental in men with T2DM.
Henrik H Thomsen, Holger J Møller, Christian Trolle, Kristian A Groth, Anne Skakkebæk, Anders Bojesen, Christian Høst and Claus H Gravholt
Soluble CD163 (sCD163) is a novel marker linked to states of low-grade inflammation such as diabetes, obesity, liver disease, and atherosclerosis, all prevalent in subjects with Turner syndrome (TS) and Klinefelter syndrome (KS). We aimed to assess the levels of sCD163 and the regulation of sCD163 in regards to treatment with sex hormone therapy in males with and without KS and females with and without TS. Males with KS (n=70) and age-matched controls (n=71) participating in a cross-sectional study and 12 healthy males from an experimental hypogonadism study. Females with TS (n=8) and healthy age-matched controls (n=8) participating in a randomized crossover trial. The intervention comprised of treatment with sex steroids. Males with KS had higher levels of sCD163 compared with controls (1.75 (0.47–6.90) and 1.36 (0.77–3.11) respectively, P<0.001) and the levels correlated to plasma testosterone (r=−0.31, P<0.01), BMI (r=0.42, P<0.001), and homeostasis model of assessment insulin resistance (r=0.46, P<0.001). Treatment with testosterone did not significantly lower sCD163. Females with TS not receiving hormone replacement therapy (HRT) had higher levels of sCD163 than those of their age-matched healthy controls (1.38±0.44 vs 0.91±0.40, P=0.04). HRT and oral contraceptive therapy decreased sCD163 in TS by 22% (1.07±0.30) and in controls by 39% (0.55±0.36), with significance in both groups (P=0.01 and P=0.04). We conclude that levels of sCD163 correlate with endogenous testosterone in KS and are higher in KS subjects compared with controls, but treatment did not significantly lower levels. Both endogenous and exogenous estradiol in TS was associated with lower levels of sCD163.
Angela Köninger, Philippos Edimiris, Laura Koch, Antje Enekwe, Claudia Lamina, Sabine Kasimir-Bauer, Rainer Kimmig and Hans Dieplinger
Oxidative stress seems to be present in patients with polycystic ovary syndrome (PCOS). The aim of this study was to evaluate the correlation between characteristics of PCOS and serum concentrations of afamin, a novel binding protein for the antioxidant vitamin E. A total of 85 patients with PCOS and 76 control subjects were investigated in a pilot cross-sectional study design between 2009 and 2013 in the University Hospital of Essen, Germany. Patients with PCOS were diagnosed according to the Rotterdam ESHRE/ASRM-sponsored PCOS Consensus Workshop Group. Afamin and diagnostic parameters of PCOS were determined at early follicular phase. Afamin concentrations were significantly higher in patients with PCOS than in controls (odds ratio (OR) for a 10 mg/ml increase in afamin=1.3, 95% CI=1.08–1.58). This difference vanished in a model adjusting for age, BMI, free testosterone index (FTI), and sex hormone-binding globulin (SHBG) (OR=1.05, 95% CI=0.80–1.38). In patients with PCOS, afamin correlated significantly with homeostatic model assessment-insulin resistance (HOMA-IR), fasting glucose, BMI, FTI, and SHBG (P<0.001), but in a multivariate linear model, only HOMA-IR remained significantly associated with afamin (P=0.001). No correlation was observed between afamin and androgens, LH, FSH, LH/FSH ratio, antral follicle count, ovarian volume, or anti-Müllerian hormone. In conclusion, elevated afamin values may indicate a state of oxidative stress and inflammation, strongly associated with IR and offering an indicator of impaired glucose tolerance in patients with PCOS irrespective of obesity.
Mengxue Yang, Bowen Sun, Jianhui Li, Bo Yang, Jie Xu, Xue Zhou, Jie Yu, Xuan Zhang, Qun Zhang, Shan Zhou and Xiaohua Sun
The pathogenesis of Graves’ disease (GD) remains unclear. In terms of environmental factors, GD development may be associated with chronic inflammation caused by alteration of the intestinal flora. This study explored the association of intestinal flora alteration with the development of GD among the Han population in southwest China.
Design and methods
Fifteen GD patients at the Affiliated Hospital of Zunyi Medical College between March 2016 and March 2017 were randomly enrolled. Additionally, 15 sex- and age-matched healthy volunteers were selected as the control group during the same period. Fresh stool samples were collected, and bacterial 16S RNA was extracted and amplified for gene sequencing with the Illumina MiSeq platform. The sequencing results were subjected to operational taxonomic unit-based classification, classification verification, alpha diversity analysis, taxonomic composition analysis and partial least squares-discriminant analysis (PLS-DA).
The diversity indices for the GD group were lower than those for the control group. The GD group showed significantly higher abundances of Firmicutes, Proteobacteria and Actinobacillus and a higher Firmicutes/Bacteroidetes ratio than the control group. PLS-DA suggested the satisfactory classification of the flora between the GD group and the control group. The abundances of the genera Oribacterium, Mogibacterium, Lactobacillus, Aggregatibacter and Mogibacterium were significantly higher in the GD group than in the control group (P < 0.05).
The intestinal flora of GD patients was significantly different from that of the healthy population. Thus, alteration of intestinal flora may be associated with the development of GD.
Fahim Ebrahimi, Sandrine A Urwyler, Philipp Schuetz, Beat Mueller, Luca Bernasconi, Peter Neyer, Marc Y Donath and Mirjam Christ-Crain
Anti-inflammatory treatment with interleukin-1 (IL-1) antagonism decreases both cortisol and adrenocorticotropin hormone (ACTH) levels in individuals with obesity in short term. However, it remains unknown whether these effects persist upon prolonged treatment.
In this double-blind, parallel-group trial involving patients with features of the metabolic syndrome, 33 patients were randomly assigned to receive 100 mg of anakinra (recombinant human IL-1 receptor antagonist) subcutaneously twice-daily and 34 patients to receive placebo for 4 weeks. For this analysis, change in cortisol and ACTH levels from baseline to 4 weeks were predefined end points of the trial.
The mean age was 54 years, baseline cortisol levels were 314 nmol/L (IQR 241–385) and C-reactive protein (CRP) levels were 3.4 mg/L (IQR 1.7–4.8). Treatment with anakinra led to a significant decrease in cortisol levels at day 1 when compared to placebo with an adjusted between-group difference of 28 nmol/L (95% CI, −7 to −43; P = 0.03). After 4 weeks, the cortisol-lowering effect of anakinra was attenuated and overall was statistically not significant (P = 0.72). Injection-site reactions occurred in 21 patients receiving anakinra and were associated with higher CRP and cortisol levels.
IL-1 antagonism decreases cortisol levels in male patients with obesity and chronic low-grade inflammation on the short term. After prolonged treatment, this effect is attenuated, probably due to injection-site reactions (ClinicalTrials.gov, NCT02672592).