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Background We examined whether grip strength differentiates youth with obesity with increased cardiometabolic risk. Methods The sample comprised 43 youth with severe obesity (mean age 14.8, standard deviation 3.0 years) enrolled in the Childhood Overweight BioRepository of Australia. Grip strength was normalized to body mass and categorized as low and moderate/high. Results Youth with low grip strength had higher systolic blood pressure (mean difference 13 mmHg), low-density lipoprotein cholesterol (0.26 mmol/l), continuous metabolic syndrome score (0.36), and carotid intima-media thickness (0.05 mm) compared with those with moderate/high grip strength. Conclusions Low grip strength may differentiate youth with obesity with increased cardiometabolic risk.

Contains fulltext : 286838.pdf (Publisher’s version ) (Closed access) 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/m(2)) 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 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.

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 11.1 years, 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.

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 β-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 β-cell effects, NOD-derived MIN6N8 β-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 β-cell function.

This study shows how highly processed foods can cause innate immune inflammation that promotes chronic microvascular disease., 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.

Contains fulltext : 245700.pdf (Publisher’s version ) (Open Access) 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

Insulin-like growth factor binding protein 2 (IGFBP-2) may represent a critical link between body composition and insulin sensitivity. We investigated the relationship between circulating IGFBP-2 levels, body composition, insulin sensitivity, energy intake and physical activity in children with obesity. Children were recruited via the Weight Management Service at the Royal Children's Hospital, Melbourne, as part of the Childhood Overweight BioRepository of Australia (COBRA). Comprehensive anthropometric, biochemical and environmental data were collected and compared to serum IGFBP-2 levels (measured by enzyme-linked immunosorbent assay). Multiple regression modelling was used to assess the influence of circulating IGFBP-2 levels on anthropometric and biochemical measures. One hundred and ninety-four children were included in this study (46% male). Circulating IGFBP-2 negatively correlated with age, anthropometric measures, blood pressure and insulin concentration. Positive associations were observed between insulin sensitivity index-homeostasis model assessment (ISI-HOMA) and serum IGFBP-2. In multiple regression modelling, IGFBP-2 significantly contributes to variance in systolic blood pressure (-19%, P < 0.05), circulating triglycerides (-16%, P < 0.05) and ISI-HOMA (18%, P < 0.05). No associations were observed between dietary energy intake or physical activity and IGFBP-2 levels. Circulating IGFBP-2 levels in children with obesity correlate inversely with body mass and markers of metabolic dysfunction, and positively with insulin sensitivity. These findings suggest that reduced levels of IGFBP-2 may play an important role in the pathogenesis of obesity complications in early life.

Signaling via the receptor of advanced glycation end products (RAGE)—though complex and not fully elucidated in the setting of diabetes—is considered a key injurious pathway in the development of diabetic nephropathy (DN). We report here that RAGE deletion resulted in increased expression of fibrotic markers (collagen I and IV, fibronectin) and the inflammatory marker MCP-1 in primary mouse mesangial cells (MCs) and in kidney cortex. RNA sequencing analysis in MCs from RAGE−/− and wild-type mice confirmed these observations. Nevertheless, despite these gene expression changes, decreased responsiveness to transforming growth factor-β was identified in RAGE−/− mice. Furthermore, RAGE deletion conferred a more proliferative phenotype in MCs and reduced susceptibility to staurosporine-induced apoptosis. RAGE restoration experiments in RAGE−/− MCs largely reversed these gene expression changes, resulting in reduced expression of fibrotic and inflammatory markers. This study highlights that protection against DN in RAGE knockout mice is likely to be due in part to the decreased responsiveness to growth factor stimulation and an antiapoptotic phenotype in MCs. Furthermore, it extends our understanding of the role of RAGE in the progression of DN, as RAGE seems to play a key role in modulating the sensitivity of the kidney to injurious stimuli such as prosclerotic cytokines.

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

The accumulation of advanced glycation end products (AGEs) have been implicated in the development and progression of diabetic kidney disease (DKD). There has been interest in investigating the potential of AGE clearance receptors, such as oligosaccharyltransferase-48kDa subunit (OST48) to prevent the detrimental effects of excess AGE accumulation seen in the diabetic kidney. Here the objective of the study was to increase the expression of OST48 to examine if this slowed the development of DKD by facilitating the clearance of AGEs. Groups of 8-week-old heterozygous knock-in male mice (n=9-12/group) over-expressing the gene encoding for OST48, dolichyl-diphosphooligosaccharide-protein glycosyltransferase (DDOST+/-) and litter mate controls were randomised to either (i) no diabetes or (ii) diabetes induced via multiple low-dose streptozotocin and followed for 24 weeks. By the study end, global over expression of OST48 increased glomerular OST48. This facilitated greater renal excretion of AGEs but did not affect circulating or renal AGE concentrations. Diabetes resulted in kidney damage including lower glomerular filtration rate, albuminuria, glomerulosclerosis and tubulointerstitial fibrosis. In diabetic mice, tubulointerstitial fibrosis was further exacerbated by global increases in OST48. There was significantly insulin effectiveness, increased acute insulin secretion, fasting insulin concentrations and AUCinsulin observed during glucose tolerance testing in diabetic mice with global elevations in OST48 when compared to diabetic wild-type littermates. Overall, this study suggested that despite facilitating urinaryrenal AGE clearance, there were no benefits observed on kidney functional and structural parameters in diabetes afforded by globally increasing OST48 expression. However, the improvements in insulin secretion seen in diabetic mice with global over-expression of OST48 and their dissociation from effects on kidney function warrant future investigation.

TheAGERgene encodes for a number of RAGE isoforms, with the membrane bound signal transduction and “decoy” circulating soluble RAGE being the best characterised. Here we demonstrate a novel nuclear isoform of RAGE in mice and human kidney cortex which by cell and size fractionation we determined to be approximately 37kda. This nuclear RAGE isoform is functional and binds to DNA sequences within the upstream 5’ promoter region of its own gene,AGER. This binding was shown to be abrogated by mutating the DNA consensus binding sequences during electromobility shift assay (EMSA) and was independent of NF-□B or AP-1 binding. Cotransfection of expression constructs encoding various RAGE isoforms along withAGERgene promoter reporter-plasmids identified that the most likely source of the nuclear isoform of RAGE was a cleavage product of the nt-RAGE isoform. In obese mice with impaired kidney function, there was increased binding of nuclear RAGE within the A. Region ofagergene promoter with corresponding increases in membrane bound RAGE in renal cells. These findings were reproducedin vitrousing proximal tubule cells. Hence, we postulate that RAGE expression is in part, self-regulated by the binding of a nuclear RAGE isoform to the promoter of theAGERgene (encoding RAGE) in the kidney. We also suggest that this RAGE self-regulation is altered under pathological conditions and this may have implications for chronic kidney disease.

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.

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. 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. 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

Liver glycogen, a highly branched polymer, acts as our blood-glucose buffer. While past structural studies have extracted glycogen from fresh or frozen tissue using a cold-water, sucrose-gradient centrifugation technique, a method for the extraction of glycogen from formalin-fixed liver would allow the analysis of glycogen from human tissues that are routinely collected in pathology laboratories. In this study, both sucrose-gradient and formalin-fixed extraction techniques were carried out on piglet livers, with the yields, purities and size distributions (using size exclusion chromatography) compared. The formalin extraction technique, when combined with a protease treatment, resulted in higher yields (but lower purities) of glycogen with size distributions similar to the sucrose-gradient centrifugation technique. This formalin extraction procedure was also significantly faster, allowing glycogen extraction throughput to increase by an order of magnitude. Both extraction techniques were compatible with mass spectrometry proteomics, with analysis showing the two techniques were highly complementary.

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. 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. 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-β 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. 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.

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-β1 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.

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-β ) 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- β , 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. Low interleukin-6 released from adipocytes might be associated with accelerated renal impairment. copy; 2011 Asian Pacific Society of Nephrology.

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.

A diet high in fat induces cardiac hypertrophy, inflammation, and oxidative stress. Although such actions have largely been ascribed to fat deposition, the accumulation of advanced glycation end products (AGEs) and subsequent activation of the receptor for AGEs (RAGE) may also represent important mediators of cardiac injury following exposure to a Western diet. In this study, male C57BL6J and RAGE knockout mice were placed on either a standard diet (7% fat) or a Western “fast-food” diet (21% fat). Animals receiving a high-fat diet were further randomized to receive the AGE inhibitor alagebrium chloride (1 mg·kg−1·day−1) and followed for 16 wk. A Western diet was associated with cardiac hypertrophy, inflammation, mitochondrial-dependent superoxide production, and cardiac AGE accumulation in wild-type mice. Although RAGE-KO mice fed a Western diet also became obese and accumulated intramyocardial lipid, cardiomyocyte hypertrophy, inflammation, and oxidative stress were attenuated compared with wild-type mice. Similarly, mice of both strains receiving alagebrium chloride had reduced levels of inflammation and oxidative stress, in association with a reduction in cardiac AGEs and RAGE. This study suggests that AGEs represent important mediators of cardiac injury associated with a Western fast-food diet. These data point to the potential utility of AGE-reducing strategies in the prevention and management of cardiac disease.

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein with dual roles in redox signaling and programmed cell death. Deficiency in AIF is known to result in defective oxidative phosphorylation (OXPHOS), via loss of complex I activity and assembly in other tissues. Because the kidney relies on OXPHOS for metabolic homeostasis, we hypothesized that a decrease in AIF would result in chronic kidney disease (CKD). Here, we report that partial knockdown of Aif in mice recapitulates many features of CKD, in association with a compensatory increase in the mitochondrial ATP pool via a shift toward mitochondrial fusion, excess mitochondrial reactive oxygen species production, and Nox4 upregulation. However, despite a 50% lower AIF protein content in the kidney cortex, there was no loss of complex I activity or assembly. When diabetes was superimposed onto Aif knockdown, there were extensive changes in mitochondrial function and networking, which augmented the renal lesion. Studies in patients with diabetic nephropathy showed a decrease in AIF within the renal tubular compartment and lower AIFM1 renal cortical gene expression, which correlated with declining glomerular filtration rate. Lentiviral overexpression of Aif1m rescued glucose-induced disruption of mitochondrial respiration in human primary proximal tubule cells. These studies demonstrate that AIF deficiency is a risk factor for the development of diabetic kidney disease.

After the discovery of the db gene in 1966, it was determined that a blood-borne satiety factor was produced excessively, but was not responded to, in db/db mice. This model for type 2 diabetes is widely used since it phenocopies human disease and its co-morbidities including obesity, progressive deterioration in glucose tolerance, hypertension and hyperlipidaemia. Db/db mice, unlike their non-diabetic controls, have consistently elevated levels of liver glycogen, most likely due to hyperphagia. In transmission electron micrographs, liver glycogen usually shows a composite cauliflower-like morphology of large "α particles" (with a wide range of sizes) made up of smaller "β particles" bound together. New studies have explored the size distribution of liver glycogen molecules and found that α particles in db/db mice are more chemically fragile than those in healthy mice, and can readily break apart to smaller β particles. There is evidence that smaller glycogen particles have a higher association with glycogen phosphorylase, a key enzyme involved in glycogen degradation, as well as being degraded more rapidly in vitro; therefore the inability to form stable large glycogen α particles is predicted to result in a faster, less controlled degradation into glucose. The implications of this for glycaemic control remain to be fully elucidated. However, "rescuing" the more fragile diabetic glycogen to decrease hepatic glucose output in type 2 diabetes, may provide a potential therapeutic target which is the subject of this review.

In type 2 diabetes, hyperglycemia is present when an increased demand for insulin, typically due to insulin resistance, is not met as a result of progressive pancreatic beta cell dysfunction. This defect in beta cell activity is typically characterized by impaired insulin biosynthesis and secretion, usually accompanied by oxidative and endoplasmic reticulum (ER) stress. We demonstrate that multiple inflammatory cytokines elevated in diabetic pancreatic islets induce beta cell oxidative and ER stress, with interleukin-23 (IL-23), IL-24 and IL-33 being the most potent. Conversely, we show that islet-endogenous and exogenous IL-22, by regulating oxidative stress pathways, suppresses oxidative and ER stress caused by cytokines or glucolipotoxicity in mouse and human beta cells. In obese mice, antibody neutralization of IL-23 or IL-24 partially reduced beta cell ER stress and improved glucose tolerance, whereas IL-22 administration modulated oxidative stress regulatory genes in islets, suppressed ER stress and inflammation, promoted secretion of high-quality efficacious insulin and fully restored glucose homeostasis followed by restitution of insulin sensitivity. Thus, therapeutic manipulation of immune regulators of beta cell stress reverses the hyperglycemia central to diabetes pathology.

Glycaemic control, reduction of blood pressure using agents that block the renin-angiotensin system and control of dyslipidaemia are the major strategies used in the clinical management of patients with diabetes mellitus. Each of these approaches interrupts a number of pathological pathways, which directly contributes to the vascular complications of diabetes mellitus, including renal disease, blindness, neuropathy and cardiovascular disease. However, research published over the past few years has indicated that many of the pathological pathways important in the development of the vascular complications of diabetes mellitus are equally relevant to the initiation of diabetes mellitus itself. These pathways include insulin signalling, generation of cellular energy, post-translational modifications and redox imbalances. This Review will examine how the development of diabetes mellitus has come full circle from initiation to complications and suggests that the development of diabetes mellitus and the progression to chronic complications both require the same mechanistic triggers.

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.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.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-β1 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.Diabetic mice given a low-AGE diet still developed renal disease, which could be attenuated by targeting of the AGE-RAGE axis.

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.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-β(1) ) activity and monocyte chemotactic protein-1 (MCP-1) levels were measured via ELISA.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-β(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.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.

Cardiovascular benefits of ubiquinone have been previously demonstrated, and we administered it as a novel therapy in an experimental model of type 2 diabetic nephropathy. db/db and dbH mice were followed for 10 weeks, after randomization to receive either vehicle or ubiquinone (CoQ10; 10mg/kg/day) orally. db/db mice had elevated urinary albumin excretion rates and albumin:creatinine ratio, not seen in db/db CoQ10-treated mice. Renal cortices from db/db mice had lower total and oxidized CoQ10 content, compared with dbH mice. Mitochondria from db/db mice also contained less oxidized CoQ10(ubiquinone) compared with dbH mice. Diabetes-induced increases in total renal collagen but not glomerulosclerosis were significantly decreased with CoQ10 therapy. Mitochondrial superoxide and ATP production via complex II in the renal cortex were increased in db/db mice, with ATP normalized by CoQ10. However, excess renal mitochondrial hydrogen peroxide production and increased mitochondrial membrane potential seen in db/db mice were attenuated with CoQ10. Renal superoxide dismutase activity was also lower in db/db mice compared with dbH mice. Our results suggest that a deficiency in mitochondrial oxidized CoQ10 (ubiquinone) may be a likely precipitating factor for diabetic nephropathy. Therefore CoQ10 supplementation may be renoprotective in type 2 diabetes, via preservation of mitochondrial function.

Background. Advanced glycation end-products (AGEs) and their receptors are prominent contributors to diabetic kidney disease.Methods. Flow cytometry was used to measure the predictive capacity for kidney impairment of the AGE receptors RAGE, AGE-R1, and AGE-R3 on peripheral blood mononuclear cells (PBMCs) in experimental models of type 2 diabetes (T2DM) fed varied AGE containing diets and in obese type 2 diabetic and control human subjects.Results. Diets high in AGE content fed to diabetic mice decreased cell surface RAGE on PBMCs and in type 2 diabetic patients with renal impairment (RI). All diabetic mice had elevated Albumin excretion rates (AERs), and high AGE fed dbdb mice had declining Glomerular filtration rate (GFR). Cell surface AGE-R1 expression was also decreased by high AGE diets and with diabetes in dbdb mice and in humans with RI. PBMC expression of AGE R3 was decreased in diabetic dbdb mice or with a low AGE diet.Conclusions. The most predictive PBMC profile for renal disease associated with T2DM was an increase in the cell surface expression of AGE-R1, in the context of a decrease in membranous RAGE expression in humans, which warrants further investigation as a biomarker for progressive DN in larger patient cohorts.

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.

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.

for 30-min after exit from the hyperbaric chamber whilst breathing normobaric air. Reductions in serum inflammatory markers MCP-1 and TNFwere observed after 4 days of HBOT in both groups (P < 0.05), whilst IL-6 was increased in non-diabetics only (P = 0.05). The increase in IL-6 correlated with the increase in insulin sensitivity (r2 = .36, p = .02). Conclusion: Insulin sensitivity was increased by HBOT in individuals with and without type 2 diabetes and this effect was maintained for at least 30-min after exit from the hyperbaric chamber. Changes in inflammatory cytokines may partly explain this effect.

Background: Advanced glycation end products (AGE)-receptor for AGE (RAGE) axis and renin-angiotensin system (RAS) play a role in diabetic nephropathy (DN). Matrix metalloproteinase-2 (MMP-2) activation also contributes to DN. However, the pathological interaction among AGE-RAGE, RAS and MMP-2 in DN remains unknown. We examined here the involvement of AGE and RAS in MMP-2 activation in streptozotocin (STZ)-induced diabetic rats and in AGE-exposed rat renal proximal tubular cells (RPTCs). Methods: Experimental diabetes was induced in 6-week-old male Sprague–Dawley (SD) rats by intravenous injection of STZ. Diabetic rats received ramipril (3 mg/kg body weight/day) or vehicle for 32 weeks. AGE-modified rat serum albumin (AGE-RSA) or RSA was intraperitoneally administrated to 6-week-old male SD rats for 16 weeks. RPTCs were stimulated with 100 μg/ml AGE-modified bovine serum albumin (AGE-BSA) or BSA in the presence or absence of 10 �7 M ramiprilat, an inhibitor of angiotensin-converting enzyme or 100 nM BAY11-7082, an IκB-α phosphorylation inhibitor. Results: AGE and RAGE expression levels and MMP-2 activity in the tubules of diabetic rats was significantly increased in association with increased albuminuria, all of which were blocked by ramipril. AGE infusion induced tubular MMP-2 activation and RAGE gene expression in SD rats. Ramiprilat or BAY11-7082 inhibited the AGE-induced MMP-2 activation or reactive oxygen species generation in RPTCs. Angiotensin II increased MMP-2 gene expression in RPTCs, which was blocked by BAY11-7082. Conclusions: Our present study suggests the involvement of AGE-RAGE-induced, RAS-mediated MMP-2 activation in experimental DN. Blockade of AGE-RAGE axis by ramipril may protect against DN partly via suppression of MMP-2.