Glucagon-like peptide-1 receptor signaling modifies the extent of diabetic kidney disease through dampening the receptor for advanced glycation end products-induced inflammation.

Glucagon like peptide-1 (GLP-1) is a hormone produced and released by cells of the gastrointestinal tract following meal ingestion. GLP-1 receptor agonists (GLP-1RA) exhibit kidney-protective actions through poorly understood mechanisms. Here we interrogated whether the receptor for advanced glycation end products (RAGE) plays a role in mediating the actions of GLP-1 on inflammation and diabetic kidney disease. Mice with deletion of the GLP-1 receptor displayed an abnormal kidney phenotype that was accelerated by diabetes and improved with co-deletion of RAGE in vivo. Activation of the GLP-1 receptor pathway with liraglutide, an anti-diabetic treatment, downregulated kidney RAGE, reduced the expansion of bone marrow myeloid progenitors, promoted M2-like macrophage polarization and lessened markers of kidney damage in diabetic mice. Single cell transcriptomics revealed that liraglutide induced distinct transcriptional changes in kidney endothelial, proximal tubular, podocyte and macrophage cells, which were dominated by pathways involved in nutrient transport and utilization, redox sensing and the resolution of inflammation. The kidney-protective action of liraglutide was corroborated in a non-diabetic model of chronic kidney disease, the subtotal nephrectomised rat. Thus, our findings identify a novel glucose-independent kidney-protective action of GLP-1-based therapies in diabetic kidney disease and provide a valuable resource for exploring the cell-specific kidney transcriptional response ensuing from pharmacological GLP-1R agonism.

Decreasing severity of obesity from early to late adolescence and young adulthood associates with longitudinal metabolomic changes implicated in lower cardiometabolic disease risk.

BACKGROUND: Obesity in childhood is associated with metabolic dysfunction, adverse subclinical cardiovascular phenotypes and adult cardiovascular disease. Longitudinal studies of youth with obesity investigating changes in severity of obesity with metabolomic profiles are sparse. We investigated associations between (i) baseline body mass index (BMI) and follow-up metabolomic profiles; (ii) change in BMI with follow-up metabolomic profiles; and (iii) change in BMI with change in metabolomic profiles (mean interval 5.5 years). METHODS: Participants (n = 98, 52% males) were recruited from the Childhood Overweight Biorepository of Australia study. At baseline and follow-up, BMI and the % >95th BMI-centile (percentage above the age-, and sex-specific 95th BMI-centile) indicate severity of obesity, and nuclear magnetic resonance spectroscopy profiling of 72 metabolites/ratios, log-transformed and scaled to standard deviations (SD), was performed in fasting serum. Fully adjusted linear regression analyses were performed. RESULTS: Mean (SD) age and % >95th BMI-centile were 10.3 (SD 3.5) years and 134.6% (19.0) at baseline, 15.8 (3.7) years and 130.7% (26.2) at follow-up. Change in BMI over time, but not baseline BMI, was associated with metabolites at follow-up. Each unit (kg/m2) decrease in sex- and age-adjusted BMI was associated with change (SD; 95% CI; p value) in metabolites of: alanine (-0.07; -0.11 to -0.04; p < 0.001), phenylalanine (-0.07; -0.10 to -0.04; p < 0.001), tyrosine (-0.07; -0.10 to -0.04; p < 0.001), glycoprotein acetyls (-0.06; -0.09 to -0.04; p < 0.001), degree of fatty acid unsaturation (0.06; 0.02 to 0.10; p = 0.003), monounsaturated fatty acids (-0.04; -0.07 to -0.01; p = 0.004), ratio of ApoB/ApoA1 (-0.05; -0.07 to -0.02; p = 0.001), VLDL-cholesterol (-0.04; -0.06 to -0.01; p = 0.01), HDL cholesterol (0.05; 0.08 to 0.1; p = 0.01), pyruvate (-0.08; -0.11 to -0.04; p < 0.001), acetoacetate (0.07; 0.02 to 0.11; p = 0.005) and 3-hydroxybuturate (0.07; 0.02 to 0.11; p = 0.01). Results using the % >95th BMI-centile were largely consistent with age- and sex-adjusted BMI measures. CONCLUSIONS: In children and young adults with obesity, decreasing the severity of obesity was associated with changes in metabolomic profiles consistent with lower cardiovascular and metabolic disease risk in adults.

Time spent watching television impacts on body mass index in youth with obesity, but only in those with shortest sleep duration.

AIM: To determine the interplay between sleep and sedentary behaviours on body mass index (BMI) in children with obesity. METHODS: Cross-sectional study of 343 children with obesity aged 4-17 years, from a tertiary care weight management clinic in Melbourne, Victoria, Australia. Multifaceted data relating to activity and sleep from child and parent questionnaires analysed with anthropometric data collected during routine clinical care. Associations between sleep duration and activity measures were examined via regression models with adjustment for potential confounders. RESULTS: Higher BMI was associated with more hours spent watching television (P = 0.04), as well as less reported enjoyment of physical activity (P = 0.005) and less time spent in organised sport activity (P = 0.005). Higher BMI was also associated with higher levels of obstructive sleep apnoea (P = 0.002). Less time in bed was associated with higher levels of BMI (P = 0.03) but analysis by sex revealed this association to only hold for males. In the whole group, a significant television and sleep interaction was seen, such that increasing television watching was associated with higher BMI, but only in those with shortest sleep duration. CONCLUSIONS: Both poor sleep and increasing screen time (including television viewing, smart-phone use, internet use or video-gaming) appear to impact BMI in children with obesity, with a particular detrimental effect of television viewing in those who sleep less. Efforts to improve sleep time and quality in children may minimise negative effects of screen time on increasing BMI and should be included in public health strategies to combat obesity in childhood.

Sex and puberty-related differences in metabolomic profiles associated with adiposity measures in youth with obesity.

BACKGROUND: Specific patterns of metabolomic profiles relating to cardiometabolic disease are associated with increased weight in adults. In youth with obesity, metabolomic data are sparse and associations with adiposity measures unknown. OBJECTIVES: Primary, to determine associations between adiposity measures and metabolomic profiles with increased cardiometabolic risks in youth with obesity. Secondary, to stratify associations by sex and puberty. METHODS: Participants were from COBRA (Childhood Overweight BioRepository of Australia; a paediatric cohort with obesity). Adiposity measures (BMI, BMI z-score, %truncal and %whole body fat, waist circumference and waist/height ratio), puberty staging and NMR metabolomic profiles from serum were assessed. Statistics included multivariate analysis (principal component analysis, PCA) and multiple linear regression models with false discovery rate adjustment. RESULTS: 214 participants had metabolomic profiles analyzed, mean age 11.9 years (SD ± 3.1), mean BMI z-score 2.49 (SD ± 0.24), 53% females. Unsupervised PCA identified no separable clusters of individuals. Positive associations included BMI z-score and phenylalanine, total body fat % and lipids in medium HDL, and waist circumference and tyrosine; negative associations included total body fat % and the ratio of docosahexaenoic acid/total fatty acids and histidine. Stratifying by sex and puberty, patterns of associations with BMI z-score in post-pubertal males included positive associations with lipid-, cholesterol- and triglyceride-content in VLDL lipoproteins; total fatty acids; total triglycerides; isoleucine, leucine and glycoprotein acetyls. CONCLUSION: In a paediatric cohort with obesity, increased adiposity measures, especially in post-pubertal males, were associated with distinct patterns in metabolomic profiles.

Psychosocial measures and weight change in a clinical paediatric population with obesity.

PURPOSE: Poor quality of life has been shown to occur in youth with obesity. This study aimed to assess associations between health-related quality of life, general mental health and general psychological distress measures, collectively termed psychosocial health questionnaires (PSH), with weight outcomes in a busy paediatric weight management service. METHODS: A cross-sectional longitudinal clinical cohort, 'Childhood Overweight BioRepository of Australia (COBRA)', was used (n = 250, median age 11, range 2-18 year, mean BMI z-score 2.5 ± 0.2). Clinical data were collected and HRQOL questionnaires; Pediatric Quality of Life 4.0 (PedsQL), 'Sizing Me/Them Up' (SMU/STU), and psychological well-being questionnaires; strengths and difficulties questionnaire (SDQ) and Kessler 10 (K10) were completed by the child and primary caregiver. PSH results were compared to age- and sex-adjusted BMI z-score at baseline and follow-up. Direct logistic regression modelling was performed to assess the impact of PSH factors on the likelihood of successful weight reduction over a period of ≥ 12 months. RESULTS: Mean self-report PSH scores were: 68.0 ± 15.28 (PedsQL, range 0-100), 64.8 ± 15.8, (SMU, range 0-100), 17.3 ± 4.4 (SDQ, range 0-40) and 20.0 ± 7.7 (K10, range 0-50). A significant negative correlation was observed between PSH scores and childhood obesity (baseline BMI z-scores (p < 0.01)). No correlations were observed between psychological well-being measures and BMI z-scores. Higher subscale scores of the PedsQL and SDQ, which measure impaired psychosocial health and more difficulties with hyperactivity and inattention, significantly predict weight loss in children with obesity after 12 months. CONCLUSION: PSH questionnaires may be useful in identifying individuals who require additional support to achieve weight loss goals in a tertiary weight management service.

Maternal inheritance of BDNF deletion, with phenotype of obesity and developmental delay in mother and child.

Childhood obesity is a significant world health problem. Understanding the genetic and environmental factors contributing to the development of obesity in childhood is important for the rational design of strategies for obesity prevention and treatment. Brain-derived neurotrophic factor (BDNF) plays an important role in the growth and development of the central nervous system, there is also an evidence that BDNF plays a role in regulation of appetite. Disruption of the expression of this gene in a child has been previously reported to result in a phenotype of severe obesity, hyperphagia, impaired cognitive function, and hyperactivity. We report a mother and child, both with micro-deletions encompassing the BDNF gene locus, who both have obesity and developmental delay, although without hyperactivity. This report highlights the maternal inheritance of a rare genetic cause of childhood obesity.

Mapping time-course mitochondrial adaptations in the kidney in experimental diabetes.

Oxidative phosphorylation (OXPHOS) drives ATP production by mitochondria, which are dynamic organelles, constantly fusing and dividing to maintain kidney homoeostasis. In diabetic kidney disease (DKD), mitochondria appear dysfunctional, but the temporal development of diabetes-induced adaptations in mitochondrial structure and bioenergetics have not been previously documented. In the present study, we map the changes in mitochondrial dynamics and function in rat kidney mitochondria at 4, 8, 16 and 32 weeks of diabetes. Our data reveal that changes in mitochondrial bioenergetics and dynamics precede the development of albuminuria and renal histological changes. Specifically, in early diabetes (4 weeks), a decrease in ATP content and mitochondrial fragmentation within proximal tubule epithelial cells (PTECs) of diabetic kidneys were clearly apparent, but no changes in urinary albumin excretion or glomerular morphology were evident at this time. By 8 weeks of diabetes, there was increased capacity for mitochondrial permeability transition (mPT) by pore opening, which persisted over time and correlated with mitochondrial hydrogen peroxide (H2O2) generation and glomerular damage. Late in diabetes, by week 16, tubular damage was evident with increased urinary kidney injury molecule-1 (KIM-1) excretion, where an increase in the Complex I-linked oxygen consumption rate (OCR), in the context of a decrease in kidney ATP, indicated mitochondrial uncoupling. Taken together, these data show that changes in mitochondrial bioenergetics and dynamics may precede the development of the renal lesion in diabetes, and this supports the hypothesis that mitochondrial dysfunction is a primary cause of DKD.

Deletion of bone-marrow-derived receptor for AGEs (RAGE) improves renal function in an experimental mouse model of diabetes.

AIMS/HYPOTHESIS: The AGEs and the receptor for AGEs (RAGE) are known contributors to diabetic complications. RAGE also has a physiological role in innate and adaptive immunity and is expressed on immune cells. The aim of this study was to determine whether deletion of RAGE from bone-marrow-derived cells influences the pathogenesis of experimental diabetic nephropathy. METHODS: Groups (n = 8/group) of lethally irradiated 8 week old wild-type (WT) mice were reconstituted with bone marrow from WT (WT → WT) or RAGE-deficient (RG) mice (RG → WT). Diabetes was induced using multiple low doses of streptozotocin after 8 weeks of bone marrow reconstitution and mice were followed for a further 24 weeks. RESULTS: Compared with diabetic WT mice reconstituted with WT bone marrow, diabetic WT mice reconstituted with RG bone marrow had lower urinary albumin excretion and podocyte loss, more normal creatinine clearance and less tubulo-interstitial injury and fibrosis. However, glomerular collagen IV deposition, glomerulosclerosis and cortical levels of TGF-ß were not different among diabetic mouse groups. The renal tubulo-interstitium of diabetic RG → WT mice also contained fewer infiltrating CD68(+) macrophages that were activated. Diabetic RG → WT mice had lower renal cortical concentrations of CC chemokine ligand 2 (CCL2), macrophage inhibitory factor (MIF) and IL-6 than diabetic WT → WT mice. Renal cortical RAGE ligands S100 calgranulin (S100A)8/9 and AGEs, but not high mobility box protein B-1 (HMGB-1) were also decreased in diabetic RG → WT compared with diabetic WT → WT mice. In vitro, bone-marrow-derived macrophages from WT but not RG mice stimulated collagen IV production in cultured proximal tubule cells. CONCLUSIONS/INTERPRETATION: These studies suggest that RAGE expression on haemopoietically derived immune cells contributes to the functional changes seen in diabetic nephropathy by promoting macrophage infiltration and renal tubulo-interstitial damage.

Targeting the AGE-RAGE axis improves renal function in the context of a healthy diet low in advanced glycation end-product content.

AIM: Mouse chow is commonly high in advanced glycation end-products, known contributors to diabetic nephropathy. The aim of this study was to evaluate if targeting of the AGE-RAGE axis was still effective in the context of a diet low in AGE content, which is more comparable to diets consumed by individuals with type 1 diabetes. METHODS: C57BL/6J wild-type and mice deficient in the receptor for AGEs (RAGE-KO) consumed a diet low in AGE content. Groups of mice were given (i) vehicle; (ii) streptozotocin; or (iii) streptozotocin + AGE lowering therapy (alagebrium chloride) and followed for 24 weeks. RESULTS: Diabetic mice had high urinary albumin excretion rates, hyperfiltration and release of urinary Kim-1, not seen in diabetic RAGE-KO mice. Diabetic mice also had renal fibrosis, measured by glomerulosclerosis, tubulointerstitial expansion, TGF-ß1 and glomerular collagen-IV deposition which almost all improved by RAGE-KO or alagebium. Diabetic mice had a greater renal burden of AGEs and increased expression of renal specific PKC-α phosphorylation, which was improved in RAGE-KO mice, or those treated with alagebrium. CONCLUSION: Diabetic mice given a low-AGE diet still developed renal disease, which could be attenuated by targeting of the AGE-RAGE axis.

Change in adiposity is associated with change in glycoprotein acetyls but not hsCRP in adolescents with severe obesity.

BACKGROUND: Obesity-associated chronic inflammation mediates the development of adverse cardiometabolic outcomes. There are sparse data on associations between severe obesity and inflammatory biomarkers in adolescence; most are cross-sectional and limited to acute phase reactants. Here, we investigate associations between adiposity measures and inflammatory biomarkers in children and adolescents with severe obesity both cross-sectionally and longitudinally. METHODS: From the Childhood Overweight Biorepository of Australia (COBRA) study, a total of n = 262 participants, mean age 11.5 years (SD 3.5) with obesity had measures of adiposity (body mass index, BMI; % above the 95th BMI-centile, %>95th BMI-centile; waist circumference, WC; waist/height ratio, WtH; % total body fat, %BF; % truncal body fat, %TF) and inflammation biomarkers (glycoprotein acetyls, GlycA; high-sensitivity C-Reactive Protein, hsCRP; white blood cell count, WBC; and neutrophil/lymphocyte ratio, NLR) assessed at baseline. Ninety-eight individuals at mean age of 15.9 years (3.7) participated in a follow-up study 5.6 (2.1) years later. Sixty-two individuals had longitudinal data. Linear regression models, adjusted for age and sex for cross-sectional analyses were applied. To estimate longitudinal associations between change in adiposity measures with inflammation biomarkers, models were adjusted for baseline measures of adiposity and inflammation. RESULTS: All adiposity measures were cross-sectionally associated with GlycA, hsCRP and WBC at both time points. Change in BMI, %>95th BMI-centile, WC, WtH and %TF were associated with concomitant change in GlycA and WBC, but not in hsCRP and NLR. CONCLUSION: GlycA and WBC but not hsCRP and NLR may be useful in assessing adiposity-related severity of chronic inflammation over time.

Obesity-induced renal impairment is exacerbated in interleukin-6-knockout mice.

AIM: Interleukin-6 (IL-6) is secreted from adipose tissue and thought to contribute to obesity-related disorders. The aim of this study was to assess if IL-6-knockout (IL-6-/-) mice would develop obesity-induced renal impairment. METHODS: Wild-type (WT) and IL-6-/- mice were high-fat fed (HFF) for 16 weeks to induce obesity. At the end of the study, renal function was measured via albumin/creatinine ratio and serum creatinine levels, using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). Glomerulosclerotic index (GSI) was scored in periodic acid Schiff-stained sections and collagen IV accumulation was assessed by immunohistochemistry. Renal cortical tumour growth factor beta (TGF-ß(1) ) activity and monocyte chemotactic protein-1 (MCP-1) levels were measured via ELISA. RESULTS: Renal IL-6 concentrations were increased with obesity. Although both WT HFF and IL-6-/- HFF mice exhibited renal impairment as measured by increased serum creatinine and urinary albumin/creatinine ratios, this was exacerbated in IL-6-/- mice. Obese mice had renal activation of cortical TGF-ß(1) , which was also higher in IL-6-/- mice. Collagen IV staining was not affected by obesity. GSI was increased with obesity in both WT and IL-6-/- mice. CONCLUSION: Obese IL-6-/- mice demonstrated renal functional and structural abnormalities above that seen in obese WT mice. We suggest that absence or low IL-6 levels may be an important accelerating factor implicated in the development and progression of obesity-induced renal disease.

Targeted reduction of advanced glycation improves renal function in obesity.

Obesity is highly prevalent in Western populations and is considered a risk factor for the development of renal impairment. Interventions that reduce the tissue burden of advanced glycation end-products (AGEs) have shown promise in stemming the progression of chronic disease. Here we tested if treatments that lower tissue AGE burden in patients and mice would improve obesity-related renal dysfunction. Overweight and obese individuals (body mass index (BMI) 26-39 kg/m(2)) were recruited to a randomized, crossover clinical trial involving 2 weeks each on a low- and a high-AGE-containing diet. Renal function and an inflammatory profile (monocyte chemoattractant protein-1 (MCP-1) and macrophage migration inhibitory factor (MIF)) were improved following the low-AGE diet. Mechanisms of advanced glycation-related renal damage were investigated in a mouse model of obesity using the AGE-lowering pharmaceutical, alagebrium, and mice in which the receptor for AGE (RAGE) was deleted. Obesity, resulting from a diet high in both fat and AGE, caused renal impairment; however, treatment of the RAGE knockout mice with alagebrium improved urinary albumin excretion, creatinine clearance, the inflammatory profile, and renal oxidative stress. Alagebrium treatment, however, resulted in decreased weight gain and improved glycemic control compared with wild-type mice on a high-fat Western diet. Thus, targeted reduction of the advanced glycation pathway improved renal function in obesity.

Modest decrease in severity of obesity in adolescence associates with low arterial stiffness.

BACKGROUND AND AIMS: Childhood obesity is associated with cardiovascular risk factors (CVRF), subclinical cardiovascular phenotypes (carotid intima-media thickness, cIMT; pulse-wave velocity, PWV; and carotid elasticity), and adult cardiovascular disease (CVD) mortality. In youth with obesity (body mass index, BMI ≥95th centile), we investigated associations between changes in adiposity and CVRF in early adolescence and subclinical cardiovascular phenotypes in late adolescence. METHODS: Participants had adiposity measures (the severity of obesity in percentage >95th BMI-centile (%>95th BMI-centile)), waist circumference (WC), percentage total body fat (%BF) and CVRF (systolic blood pressure, SBP; glycoprotein acetyls, GlycA; and low-density lipoprotein cholesterol) assessed in early (mean age 10.2 ± 3.5y) and late (15.7 ± 3.7y) adolescence. Subclinical cardiovascular phenotypes were assessed in late adolescence. Multivariable regression analysis was performed. RESULTS: Decreasing the %>95th BMI-centile was associated with carotid elasticity (0.945%/10 mmHg, p = 0.002) in females, and with PWV in males (-0.75 m/s, p < 0.001). Changes in all adiposity measures (per 1-unit increase) were associated with carotid elasticity (-0.020 to -0.063%/10 mmHg, p < 0.005), and PWV (0.011-0.045 m/s, p < 0.005). Changes in GlycA (per 50µmol-increase) were associated with elasticity (-0.162%/10 mmHg, p = 0.042), and changes in SBP (per 10 mmHg-increase) were associated with PWV (0.260 m/s, p < 0.001). Adjusted for change in BMI, the coefficient for GlycA was reduced by 46% and for SBP by 12%. Only male sex was associated with cIMT (+34 µm, p = 0.006). CONCLUSIONS: In youth with obesity, decreasing or maintaining the severity of obesity, and decreasing the levels of SBP and GlycA from early to late adolescence was associated with low arterial stiffness.

Short Duration Alagebrium Chloride Therapy Prediabetes Does Not Inhibit Progression to Autoimmune Diabetes in an Experimental Model.

Mechanisms by which advanced glycation end products (AGEs) contribute to type 1 diabetes (T1D) pathogenesis are poorly understood. Since life-long pharmacotherapy with alagebrium chloride (ALT) slows progression to experimental T1D, we hypothesized that acute ALT therapy delivered prediabetes, may be effective. However, in female, non-obese diabetic (NODShiLt) mice, ALT administered prediabetes (day 50-100) did not protect against experimental T1D. ALT did not decrease circulating AGEs or their precursors. Despite this, pancreatic ß-cell function was improved, and insulitis and pancreatic CD45.1+ cell infiltration was reduced. Lymphoid tissues were unaffected. ALT pre-treatment, prior to transfer of primed GC98 CD8+ T cell receptor transgenic T cells, reduced blood glucose concentrations and delayed diabetes, suggesting islet effects rather than immune modulation by ALT. Indeed, ALT did not reduce interferon-γ production by leukocytes from ovalbumin-pre-immunised NODShiLt mice and NODscid recipients given diabetogenic ALT treated NOD splenocytes were not protected against T1D. To elucidate ß-cell effects, NOD-derived MIN6N8 ß-cell major histocompatibility complex (MHC) Class Ia surface antigens were examined using immunopeptidomics. Overall, no major changes in the immunopeptidome were observed during the various treatments with all peptides exhibiting allele specific consensus binding motifs. As expected, longer MHC Class Ia peptides were captured bound to H-2Db than H-2Kb under all conditions. Moreover, more 10-12 mer peptides were isolated from H-2Db after AGE modified bovine serum albumin (AGE-BSA) treatment, compared with bovine serum albumin (BSA) or AGE-BSA+ALT treatment. Proteomics of MIN6N8 cells showed enrichment of processes associated with catabolism, the immune system, cell cycling and presynaptic endocytosis with AGE-BSA compared with BSA treatments. These data show that short-term ALT intervention, given prediabetes, does not arrest experimental T1D but transiently impacts ß-cell function.

Processed foods drive intestinal barrier permeability and microvascular diseases.

Intake of processed foods has increased markedly over the past decades, coinciding with increased microvascular diseases such as chronic kidney disease (CKD) and diabetes. Here, we show in rodent models that long-term consumption of a processed diet drives intestinal barrier permeability and an increased risk of CKD. Inhibition of the advanced glycation pathway, which generates Maillard reaction products within foods upon thermal processing, reversed kidney injury. Consequently, a processed diet leads to innate immune complement activation and local kidney inflammation and injury via the potent proinflammatory effector molecule complement 5a (C5a). In a mouse model of diabetes, a high resistant starch fiber diet maintained gut barrier integrity and decreased severity of kidney injury via suppression of complement. These results demonstrate mechanisms by which processed foods cause inflammation that leads to chronic disease.

Disparate effects on renal and oxidative parameters following RAGE deletion, AGE accumulation inhibition, or dietary AGE control in experimental diabetic nephropathy.

Advanced glycation end products (AGEs) and the receptor for AGEs (RAGE) generate ROS, and therefore this study evaluated the effects of RAGE deletion, decreasing AGE accumulation, or lowering dietary AGE content on oxidative parameters in diabetic nephropathy (DN). Control and diabetic male wild-type and RAGE-deficient (RAGE-/-) mice were fed high- or low-AGE diets, with two groups given the inhibitor of AGE accumulation, alagebrium chloride, and followed for 24 wk. Diabetic RAGE-/- mice were protected against albuminuria, hyperfiltration, glomerulosclerosis, decreased renal mitochondrial ATP production, and excess generation of both mitochondrial and cytosolic superoxide. Whereas glomerulosclerosis, tubulointerstitial expansion, and hyperfiltration were improved in diabetic mice treated with alagebrium, there was no effect on urinary albumin excretion. Both diabetic RAGE-/- and alagebrium-treated mice had an attenuation of renal RAGE expression and decreased renal and urinary AGE (carboxymethyllysine) levels. Low-AGE diets did not confer renoprotection, lower the AGE burden or renal RAGE expression, or improve cytosolic or mitochondrial superoxide generation. Renal uncoupling protein-2 gene expression and mitochondrial membrane potential were attenuated by all therapeutic interventions in diabetic mice. In the present study, diverse approaches to block the AGE-RAGE axis had disparate effects on DN, which has potential clinical implications for the way this axis should be targeted in humans.

RAGE-induced cytosolic ROS promote mitochondrial superoxide generation in diabetes.

Damaged mitochondria generate an excess of superoxide, which may mediate tissue injury in diabetes. We hypothesized that in diabetic nephropathy, advanced glycation end-products (AGEs) lead to increases in cytosolic reactive oxygen species (ROS), which facilitate the production of mitochondrial superoxide. In normoglycemic conditions, exposure of primary renal cells to AGEs, transient overexpression of the receptor for AGEs (RAGE) with an adenoviral vector, and infusion of AGEs to healthy rodents each induced renal cytosolic oxidative stress, which led to mitochondrial permeability transition and deficiency of mitochondrial complex I. Because of a lack of glucose-derived NADH, which is the substrate for complex I, these changes did not lead to excess production of mitochondrial superoxide; however, when we performed these experiments in hyperglycemic conditions in vitro or in diabetic rats, we observed significant generation of mitochondrial superoxide at the level of complex I, fueled by a sustained supply of NADH. Pharmacologic inhibition of AGE-RAGE-induced mitochondrial permeability transition in vitro abrogated production of mitochondrial superoxide; we observed a similar effect in vivo after inhibiting cytosolic ROS production with apocynin or lowering AGEs with alagebrium. Furthermore, RAGE deficiency prevented diabetes-induced increases in renal mitochondrial superoxide and renal cortical apoptosis in mice. Taken together, these studies suggest that AGE-RAGE-induced cytosolic ROS production facilitates mitochondrial superoxide production in hyperglycemic environments, providing further evidence of a role for the advanced glycation pathway in the development and progression of diabetic nephropathy.

Evidence for Protein Leverage in Children and Adolescents with Obesity.

OBJECTIVE: The aim of this study was to test the protein leverage hypothesis in a cohort of youth with obesity. METHODS: A retrospective study was conducted in a cohort of youth with obesity attending a tertiary weight management service. Validated food questionnaires revealed total energy intake (TEI) and percentage of energy intake from carbohydrates (%EC), fats (%EF), and proteins (%EP). Individuals with a Goldberg cutoff ≥ 1.2 of the ratio of reported TEI to basal metabolic rate from fat-free mass were included. A subgroup had accelerometer data. Statistics included modeling of percentage of energy from macronutrients and TEI, compositional data analysis to predict TEI from macronutrient ratios, and mixture models for sensitivity testing. RESULTS: A total of 137 of 203 participants were included (mean [SD] age 11.3 [2.7] years, 68 females, BMI z score 2.47 [0.27]). Mean TEI was 10,330 (2,728) kJ, mean %EC was 50.6% (6.1%), mean %EF was 31.6% (4.9%), and mean %EP was 18.4% (3.1%). The relationship between %EP and TEI followed a power function (L coefficient -0.48; P < 0.001). TEI was inversely associated with increasing %EP. In the subgroup with < 60 min/d of moderate to vigorous physical activity (n = 48), lower BMI z scores were associated with higher %EP and moderate %EC. CONCLUSIONS: In youth with obesity, protein dilution by either carbohydrates or fats increases TEI. Assessment of dietary protein may be useful to assist in reducing TEI and BMI in youth with obesity.

A new perspective on therapeutic inhibition of advanced glycation in diabetic microvascular complications: common downstream endpoints achieved through disparate therapeutic approaches?

A commonality among the chemically disparate compounds that inhibit the formation and accumulation of advanced glycation end products (AGEs) or their signalling pathways is their end organ protection in experimental models of diabetes complications. Although this group of therapeutics are structurally and functionally distinct with numerous mechanisms of action, the most important factor governing their therapeutic capability is clearly their ability to alleviate the tissue burden of advanced glycation, rather than the biochemical mechanism by which this is achieved. However, it remains to be determined if it is the reduction in tissue AGE levels per se or inhibition of downstream signal pathways which is ultimately required for end organ protection. For example, a number of these agents stimulate antioxidant defences, modify lipid profiles and inhibit low-grade inflammation. These novel actions emphasise the importance of further examination of the advanced glycation pathway and in particular the diverse action of these agents in ameliorating the development of diabetic complications such as nephropathy.

Neighbourhood socioeconomic circumstances, adiposity and cardiometabolic risk measures in children with severe obesity.

BACKGROUND: It has recently been shown that neighbourhood socioeconomic disadvantage in childhood is associated with obesity, hypertension, fatty liver, and type 2 diabetes in adulthood. However, it is largely unknown whether neighbourhood socioeconomic circumstances are important predictors of adiposity and associated measures in children, especially in those with severe obesity. Therefore, we evaluated the associations between neighbourhood socioeconomic factors with the severity of obesity, and related cardiometabolic risk factors in a cohort of obese children. METHODS: The Childhood Overweight BioRepository of Australia (COBRA) cohort study comprises 444 children (mean age 11.1years, mean BMI z-score 2.5). Neighbourhood socioeconomic advantage/disadvantage was evaluated based on postcode information by the national Australian Socio-Economic Indexes for Areas (SEIFA) scores. Participants/parents also completed self-administered questionnaires on neighbourhood related facilities, family education and family income. RESULTS: In analyses adjusted for age, sex and pubertal status, SEIFA indicating neighbourhood education/occupation was negatively associated with BMI, waist circumference and body fat%. Higher family education was associated with lower BMI. Neighbourhood walkability was related to lower waist circumference. Good shopping facilities in the neighbourhood were associated with increased risk of dyslipidemia and fatty liver, and the existence of parks and playgrounds nearby was related to dyslipidemia. CONCLUSIONS: The present data suggest that neighbourhood-related issues are associated with less severe adiposity among children with established obesity. Concerning cardiometabolic risk factors, shopping facilities were related to dyslipidemia and fatty liver. These findings suggest that increased awareness and efforts are needed to diminish socioeconomic inequalities between neighbourhoods.