Proteomics reveals novel oxidative and glycolytic mechanisms in type 1 diabetic patients' skin which are normalized by kidney-pancreas transplantation

Inhibition of acyl-CoA binding protein (ACBP) by means of a GABAARγ2-derived peptide

Acyl-CoA binding protein (ACBP) encoded by diazepam binding inhibitor (DBI) is an extracellular inhibitor of autophagy acting on the gamma-aminobutyric acid A receptor (GABAAR) γ2 subunit (GABAARγ2). Here, we show that lipoanabolic diets cause an upregulation of GABAARγ2 protein in liver hepatocytes but not in other major organs. ACBP/DBI inhibition by systemically injected antibodies has been demonstrated to mediate anorexigenic and organ-protective, autophagy-dependent effects. Here, we set out to develop a new strategy for developing ACBP/DBI antagonists. For this, we built a molecular model of the interaction of ACBP/DBI with peptides derived from GABAARγ2. We then validated the interaction between recombinant and native ACBP/DBI protein and a GABAARγ2-derived eicosapeptide (but not its F77I mutant) by pull down experiments or surface plasmon resonance. The GABAARγ2-derived eicosapeptide inhibited the metabolic activation of hepatocytes by recombinant ACBP/DBI protein in vitro. Moreover, the GABAARγ2-derived eicosapeptide (but not its F77I-mutated control) blocked appetite stimulation by recombinant ACBP/DBI in vivo, induced autophagy in the liver, and protected mice against the hepatotoxin concanavalin A. We conclude that peptidomimetics disrupting the interaction between ACBP/DBI and GABAARγ2 might be used as ACBP/DBI antagonists. This strategy might lead to the future development of clinically relevant small molecules of the ACBP/DBI system.

A Composite Biomarker Signature of Type 1 Diabetes Risk Identified via Augmentation of Parallel Multi-Omics Data from a Small Cohort

Background

Biomarkers of early pathogenesis of type 1 diabetes (T1D) are crucial to enable effective prevention measures in at-risk populations before significant damage occurs to their insulin producing beta-cell mass. We recently introduced the concept of integrated parallel multi-omics and employed a novel data augmentation approach which identified promising candidate biomarkers from a small cohort of high-risk T1D subjects. We now validate selected biomarkers to generate a potential composite signature of T1D risk.

Methods

Twelve candidate biomarkers, which were identified in the augmented data and selected based on their fold-change relative to healthy controls and cross-reference to proteomics data previously obtained in the expansive TEDDY and DAISY cohorts, were measured in the original samples by ELISA.

Results

All 12 biomarkers had established connections with lipid/lipoprotein metabolism, immune function, inflammation, and diabetes, but only 7 were found to be markedly changed in the high-risk subjects compared to the healthy controls: ApoC1 and PON1 were reduced while CETP, CD36, FGFR1, IGHM, PCSK9, SOD1, and VCAM1 were elevated.

Conclusions

Results further highlight the promise of our data augmentation approach in unmasking important patterns and pathologically significant features in parallel multi-omics datasets obtained from small sample cohorts to facilitate the identification of promising candidate T1D biomarkers for downstream validation. They also support the potential utility of a composite biomarker signature of T1D risk characterized by the changes in the above markers.

Kidney Disease and Proteomics: A Recent Overview of a Useful Tool for Improving Early Diagnosis

Kidney disease is a critical and potentially life-threatening degenerative condition that poses a significant global public health challenge due to its elevated rates of morbidity and mortality. It manifests primarily in two distinct clinical forms: acute kidney injury (AKI) and chronic kidney disease (CKD). The development of these conditions hinges on a multitude of factors, including the etiological agents and the presence of coexisting medical conditions. Despite disparities in their underlying pathogenic mechanisms, both AKI and CKD can progress to end-stage kidney disease (ESKD). This advanced stage is characterized by organ failure and its associated complications, greatly increasing the risk of mortality. There is an urgent need to delve into the pathogenic mechanisms underlying these diseases and to identify novel biomarkers that can facilitate earlier diagnosis. Such early detection is crucial for enhancing the efficacy of therapy and impeding disease progression. In this context, proteomic approaches have emerged as invaluable tools for uncovering potential new markers of different pathological conditions, including kidney diseases. In this chapter, we overview the recent discoveries achieved through diverse proteomic techniques aimed at identifying novel molecules that may play a pivotal role in kidney diseases such as diabetic kidney disease (DKD), IgA nephropathy (IgAN), CKD of unknown origin (CKDu), autosomal dominant polycystic kidney disease (ADPKD), lupus nephritis (LN), hypertensive nephropathy (HN), and COVID-19-associated acute kidney injury (COVID-AKI).

The anti-inflammatory and immunological properties of SGLT-2 inhibitors

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT-2i) are antidiabetic oral drugs that act on proximal renal tubules promoting renal glucose excretion. Although SGLT-2i belong to the class of hypoglycemic agents, in the last years great interest has emerged in studying their pleiotropic effects, beyond their ability to lower glucose levels.

PURPOSE

In this review we are describing the anti-inflammatory and immunological properties of SGLT-2i; furthermore, we are addressing how the mechanisms associated with the aforementioned anti-inflammatory properties may contribute to the beneficial effects of SGLT-2i in diabetes.

METHODS

A systematic search was undertaken for studies related the properties of SGLT-2i in reducing the inflammatory milieu of acute and chronic disease by acting on the immune system, independently by glycemia.

RESULTS

Recently, some data described the anti-inflammatory and immunological properties of SGLT-2 in both pre-clinical and clinical studies. Numerous data confirmed the cardio- and -renal protective effects of SGLT-2i in patients with heart failure and kidney diseases, with or without diabetes.

CONCLUSIONS

SGLT-2i are promising drugs with anti-inflammatory and immunological properties. Despite the mechanism of action of SGLT-2i is not fully understood, these drugs demonstrated anti-inflammatory effects, which may help in keeping under control the variety of complications associated with diabetes.

Novel small molecules inhibit proteotoxicity and inflammation: Mechanistic and therapeutic implications for Alzheimer's Disease, healthspan and lifespan- Aging as a consequence of glycolysis

Inflammation drives many age-related, especially neurological, diseases, and likely mediates age-related proteotoxicity. For example, dementia due to Alzheimer's Disease (AD), cerebral vascular disease, many other neurodegenerative conditions is increasingly among the most devastating burdens on the American (and world) health system and threatens to bankrupt the American health system as the population ages unless effective treatments are developed. Dementia due to either AD or cerebral vascular disease, and plausibly many other neurodegenerative and even psychiatric conditions, is driven by increased age-related inflammation, which in turn appears to mediate Abeta and related proteotoxic processes. The functional significance of inflammation during aging is also supported by the fact that Humira, which is simply an antibody to the pro-inflammatory cytokine TNF-a, is the best-selling drug in the world by revenue. These observations led us to develop parallel high-throughput screens to discover small molecules which inhibit age-related Abeta proteotoxicity in a C. elegans model of AD AND LPS-induced microglial TNF-a. In the initial screen of 2560 compounds (Microsource Spectrum library) to delay Abeta proteotoxicity, the most protective compounds were, in order, phenylbutyrate, methicillin, and quetiapine, which belong to drug classes (HDAC inhibitors, beta lactam antibiotics, and tricyclic antipsychotics, respectably) already robustly implicated as promising to protect in neurodegenerative diseases, especially AD. RNAi and chemical screens indicated that the protective effects of HDAC inhibitors to reduce Abeta proteotoxicity are mediated by inhibition of HDAC2, also implicated in human AD, dependent on the HAT Creb binding protein (Cbp), which is also required for the protective effects of both dietary restriction and the daf-2 mutation (inactivation of IGF-1 signaling) during aging. In addition to methicillin, several other beta lactam antibiotics also delayed Abeta proteotoxicity and reduced microglial TNF-a. In addition to quetiapine, several other tricyclic antipsychotic drugs also delayed age-related Abeta proteotoxicity and increased microglial TNF-a, leading to the synthesis of a novel congener, GM310, which delays Abeta as well as Huntingtin proteotoxicity, inhibits LPS-induced mouse and human microglial and monocyte TNF-a, is highly concentrated in brain after oral delivery with no apparent toxicity, increases lifespan, and produces molecular responses highly similar to those produced by dietary restriction, including induction of Cbp inhibition of inhibitors of Cbp, and genes promoting a shift away from glycolysis and toward metabolism of alternate (e.g., lipid) substrates. GM310, as well as FDA-approved tricyclic congeners, prevented functional impairments and associated increase in TNF-a in a mouse model of stroke. Robust reduction of glycolysis by GM310 was functionally corroborated by flux analysis, and the glycolytic inhibitor 2-DG inhibited microglial TNF-a and other markers of inflammation, delayed Abeta proteotoxicity, and increased lifespan. These results support the value of phenotypic screens to discover drugs to treat age-related, especially neurological and even psychiatric diseases, including AD and stroke, and to clarify novel mechanisms driving neurodegeneration (e.g., increased microglial glycolysis drives neuroinflammation and subsequent neurotoxicity) suggesting novel treatments (selective inhibitors of microglial glycolysis).

Acyl coenzyme A binding protein (ACBP): An aging- and disease-relevant "autophagy checkpoint"

Acyl coenzyme A binding protein (ACBP), also known as diazepam-binding inhibitor (DBI), is a phylogenetically ancient protein present in some eubacteria and the entire eukaryotic radiation. In several eukaryotic phyla, ACBP/DBI transcends its intracellular function in fatty acid metabolism because it can be released into the extracellular space. This ACBP/DBI secretion usually occurs in response to nutrient scarcity through an autophagy-dependent pathway. ACBP/DBI and its peptide fragments then act on a range of distinct receptors that diverge among phyla, namely metabotropic G protein-coupled receptor in yeast (and likely in the mammalian central nervous system), a histidine receptor kinase in slime molds, and ionotropic gamma-aminobutyric acid (GABA)A receptors in mammals. Genetic or antibody-mediated inhibition of ACBP/DBI orthologs interferes with nutrient stress-induced adaptations such as sporulation or increased food intake in multiple species, as it enhances lifespan or healthspan in yeast, plant leaves, nematodes, and multiple mouse models. These lifespan and healthspan-extending effects of ACBP/DBI suppression are coupled to the induction of autophagy. Altogether, it appears that neutralization of extracellular ACBP/DBI results in "autophagy checkpoint inhibition" to unleash the anti-aging potential of autophagy. Of note, in humans, ACBP/DBI levels increase in various tissues, as well as in the plasma, in the context of aging, obesity, uncontrolled infection or cardiovascular, inflammatory, neurodegenerative, and malignant diseases.

Antibiotic-induced gut microbiota depletion exacerbates host hypercholesterolemia

Hypercholesterolemia is a major driver of atherosclerosis, thus contributing to high morbidity and mortality worldwide. Gut microbiota have been identified as modulator of blood lipids including cholesterol levels. Few studies have already linked certain bacteria and microbial mechanisms to host cholesterol. However, in particular mouse models revealed conflicting results depending on genetics and experimental protocol. To gain further insights into the relationship between intestinal bacteria and host cholesterol metabolism, we first performed fecal 16S rRNA targeted metagenomic sequencing in a human cohort (n = 24) naïve for cholesterol lowering drugs. Here, we show alterations in the gut microbiota composition of hypercholesterolemic patients with depletion of Bifidobacteria, expansion of Clostridia and increased Firmicutes/Bacteroidetes ratio. To test whether pharmacological intervention in gut microbiota impacts host serum levels of cholesterol, we treated hypercholesterolemic Apolipoprotein E knockout with oral largely non-absorbable antibiotics. Antibiotics increased serum cholesterol, but only when mice were fed normal chow diet and cholesterol was measured in the random fed state. These elevations in cholesterol already occurred few days after treatment initiation and were reversible after stopping antibiotics with re-acquisition of intestinal bacteria. Gene expression analyses pointed to increased intestinal cholesterol uptake mediated by antibiotics in the fed state. Non-targeted serum metabolomics suggested that diminished plant sterol levels and reduced bile acid cycling were involved microbial mechanisms. In conclusion, our work further enlightens the link between gut microbiota and host cholesterol metabolism. Pharmacological disruption of the gut flora by antibiotics was able to exacerbate serum cholesterol and may impact cardiovascular disease.

Biomarkers of autoimmunity and beta cell metabolism in type 1 diabetes

Posttranslational protein modifications (PTMs) are an inherent response to physiological changes causing altered protein structure and potentially modulating important biological functions of the modified protein. Besides cellular metabolic pathways that may be dictated by PTMs, the subtle change of proteins also may provoke immune attack in numerous autoimmune diseases. Type 1 diabetes (T1D) is a chronic autoimmune disease destroying insulin-producing beta cells within the pancreatic islets, a result of tissue inflammation to specific autoantigens. This review summarizes how PTMs arise and the potential pathological consequence of PTMs, with particular focus on specific autoimmunity to pancreatic beta cells and cellular metabolic dysfunction in T1D. Moreover, we review PTM-associated biomarkers in the prediction, diagnosis and in monitoring disease activity in T1D. Finally, we will discuss potential preventive and therapeutic approaches of targeting PTMs in repairing or restoring normal metabolic pathways in pancreatic islets.

Exploring Computational Data Amplification and Imputation for the Discovery of Type 1 Diabetes (T1D) Biomarkers from Limited Human Datasets

Background: Type 1 diabetes (T1D) is a devastating disease with serious health complications. Early T1D biomarkers that could enable timely detection and prevention before the onset of clinical symptoms are paramount but currently unavailable. Despite their promise, omics approaches have so far failed to deliver such biomarkers, likely due to the fragmented nature of information obtained through the single omics approach. We recently demonstrated the utility of parallel multi-omics for the identification of T1D biomarker signatures. Our studies also identified challenges. Methods: Here, we evaluated a novel computational approach of data imputation and amplification as one way to overcome challenges associated with the relatively small number of subjects in these studies. Results: Using proprietary algorithms, we amplified our quadra-omics (proteomics, metabolomics, lipidomics, and transcriptomics) dataset from nine subjects a thousand-fold and analyzed the data using Ingenuity Pathway Analysis (IPA) software to assess the change in its analytical capabilities and biomarker prediction power in the amplified datasets compared to the original. These studies showed the ability to identify an increased number of T1D-relevant pathways and biomarkers in such computationally amplified datasets, especially, at imputation ratios close to the “golden ratio” of 38.2%:61.8%. Specifically, the Canonical Pathway and Diseases and Functions modules identified higher numbers of inflammatory pathways and functions relevant to autoimmune T1D, including novel ones not identified in the original data. The Biomarker Prediction module also predicted in the amplified data several unique biomarker candidates with direct links to T1D pathogenesis. Conclusions: These preliminary findings indicate that such large-scale data imputation and amplification approaches are useful in facilitating the discovery of candidate integrated biomarker signatures of T1D or other diseases by increasing the predictive range of existing data mining tools, especially when the size of the input data is inherently limited.

Inflammation and vascular dysfunction: The negative synergistic combination of diabetes and COVID-19

AIMS

Several reports indicate that diabetes determines an increased mortality risk in patients with coronavirus disease 19 (COVID-19) and a good glycaemic control appears to be associated with more favourable outcomes. Evidence also supports that COVID-19 pneumonia only accounts for a part of COVID-19 related deaths. This disease is indeed characterised by abnormal inflammatory response and vascular dysfunction, leading to the involvement and failure of different systems, including severe acute respiratory distress syndrome, coagulopathy, myocardial damage and renal failure. Inflammation and vascular dysfunction are also well-known features of hyperglycemia and diabetes, making up the ground for a detrimental synergistic combination that could explain the increased mortality observed in hyperglycaemic patients.

MATERIALS AND METHODS

In this work, we conduct a narrative review on this intriguing connection. Together with this, we also present the clinical characteristics, outcomes, laboratory and histopathological findings related to this topic of a cohort of nearly 1000 subjects with COVID-19 admitted to a third-level Hospital in Milan.

RESULTS

We found an increased mortality in subjects with COVID-19 and diabetes, together with an altered inflammatory profile.

CONCLUSIONS

This may support the hypothesis that diabetes and COVID-19 meet at the crossroads of inflammation and vascular dysfunction. (ClinicalTrials.gov NCT04463849 and NCT04382794).

Acute and long-term disruption of glycometabolic control after SARS-CoV-2 infection

Patients with coronavirus disease 2019 (COVID-19) are reported to have a greater prevalence of hyperglycaemia. Cytokine release as a consequence of severe acute respiratory syndrome coronavirus 2 infection may precipitate the onset of metabolic alterations by affecting glucose homeostasis. Here we describe abnormalities in glycometabolic control, insulin resistance and beta cell function in patients with COVID-19 without any pre-existing history or diagnosis of diabetes, and document glycaemic abnormalities in recovered patients 2 months after onset of disease. In a cohort of 551 patients hospitalized for COVID-19 in Italy, we found that 46% of patients were hyperglycaemic, whereas 27% were normoglycaemic. Using clinical assays and continuous glucose monitoring in a subset of patients, we detected altered glycometabolic control, with insulin resistance and an abnormal cytokine profile, even in normoglycaemic patients. Glycaemic abnormalities can be detected for at least 2 months in patients who recovered from COVID-19. Our data demonstrate that COVID-19 is associated with aberrant glycometabolic control, which can persist even after recovery, suggesting that further investigation of metabolic abnormalities in the context of long COVID is warranted.

Pioglitazone corrects dysregulation of skeletal muscle mitochondrial proteins involved in ATP synthesis in type 2 diabetes

CONTEXT

In this study, we aimed to identify the determinants of mitochondrial dysfunction in skeletal muscle (SKLM) of subjects with type 2 diabetes (T2DM), and to evaluate the effect of pioglitazone (PIO) on SKLM mitochondrial proteome.

METHODS

Two different groups of adults were studied. Group I consisted of 8 individuals with normal glucose tolerance (NGT) and 8 with T2DM, subjected to SKLM mitochondrial proteome analysis by 2D-gel electrophoresis followed by mass spectrometry-based protein identification. Group II included 24 individuals with NGT and 24 with T2DM, whose SKLM biopsies were subjected to immunoblot analysis. Of the 24 subjects with T2DM, 20 were randomized to receive placebo or PIO (15 mg daily) for 6 months. After 6 months of treatment, SKLM biopsy was repeated.

RESULTS

Mitochondrial proteomic analysis on Group I revealed that several mitochondrial proteins involved in oxidative metabolism were differentially expressed between T2DM and NGT groups, with a downregulation of ATP synthase alpha chain (ATP5A), electron transfer flavoprotein alpha-subunit (ETFA), cytochrome c oxidase subunit VIb isoform 1 (CX6B1), pyruvate dehydrogenase protein X component (ODPX), dihydrolipoamide dehydrogenase (DLDH), dihydrolipoamide-S-succinyltransferase (DLST), and mitofilin, and an up-regulation of hydroxyacyl-CoA-dehydrogenase (HCDH), 3,2-trans-enoyl-CoA-isomerase (D3D2) and delta3,5-delta2,4-dienoyl-CoA-isomerase (ECH1) in T2DM as compared to NGT subjects. By immunoblot analysis on SKLM lysates obtained from Group II we confirmed that, in comparison to NGT subjects, those with T2DM exhibited lower protein levels of ATP5A (-30%, P = 0.006), ETFA (-50%, P = 0.02), CX6B1 (-30%, P = 0.03), key factors for ATP biosynthesis, and of the structural protein mitofilin (-30%, P = 0.01). T2DM was associated with a reduced abundance of the enzymes involved in the Krebs cycle DLST and ODPX (-20%, P ≤ 0.05) and increased levels of HCDH and ECH1, enzymes implicated in the fatty acid catabolism (+30%, P ≤ 0.05). In subjects with type 2 diabetes treated with PIO for 6 months we found a restored SKLM protein abundance of ATP5A, ETFA, CX6B1, and mitofilin. Moreover, protein levels of HCDH and ECH1 were reduced by -10% and - 15% respectively (P ≤ 0.05 for both) after PIO treatment.

CONCLUSION

Type 2 diabetes is associated with reduced levels of mitochondrial proteins involved in oxidative phosphorylation and an increased abundance of enzymes implicated in fatty acid catabolism in SKLM. PIO treatment is able to improve SKLM mitochondrial proteomic profile in subjects with T2DM.

Placental proteome abnormalities in women with gestational diabetes and large-for-gestational-age newborns

INTRODUCTION

Gestational diabetes mellitus (GDM) is the most frequent metabolic complication during pregnancy and is associated with development of short-term and long-term complications for newborns, with large-for-gestational-age (LGA) being particularly common. Interestingly, the mechanism behind altered fetal growth in GDM is only partially understood.

RESEARCH DESIGN AND METHODS

A proteomic approach was used to analyze placental samples obtained from healthy pregnant women (n=5), patients with GDM (n=12) and with GDM and LGA (n=5). Effects of altered proteins on fetal development were tested in vitro in human embryonic stem cells (hESCs).

RESULTS

Here, we demonstrate that the placental proteome is altered in pregnant women affected by GDM with LGA, with at least 37 proteins differentially expressed to a higher degree (p<0.05) as compared with those with GDM but without LGA. Among these proteins, 10 are involved in regulating tissue differentiation and/or fetal growth and development, with bone marrow proteoglycan (PRG2) and dipeptidyl peptidase-4 (DPP-4) being highly expressed. Both PRG2 and DPP-4 altered the transcriptome profile of stem cells differentiation markers when tested in vitro in hESCs, suggesting a potential role in the onset of fetal abnormalities.

CONCLUSIONS

Our findings suggest that placental dysfunction may be directly responsible for abnormal fetal growth/development during GDM. Once established on a larger population, inhibitors of the pathways involving those altered factors may be tested in conditions such as GDM and LGA, in which therapeutic approaches are still lacking.

Pancreatic Tissue Proteomics Unveils Key Proteins, Pathways, and Networks Associated with Type 1 Diabetes

PURPOSE

Type 1 diabetes (T1D) is characterized by autoimmune mediated self-destruction of the pancreatic islet beta cells and the resultant insulin deficiency. However, little is known about the underlying molecular pathogenesis at the pancreatic tissue level given the limited availability of clinical specimens.

EXPERIMENTAL DESIGN

Quantitative proteomic studies is performed on age-matched T1D and healthy cadaveric pancreatic tissues (n = 18 each) using TMT 10plex-based isobaric labeling and BoxCar-based label-free LC-MS/MS approaches. ELISA is used to validate the differentially expressed proteins (DEPs).

RESULTS

Overall, the two quantitative proteomics approaches identified 8824 proteins, of which 261 are DEPs. KEGG pathway and functional network analyses of the DEPs reveal dysregulations to pancreatic exocrine function, complement coagulation cascades, and extracellular matrix receptor interaction pathways in T1D. A selected list of the DEPs associated with pathways, subnetworks, and plasma proteome of T1D are validated using ELISA.

CONCLUSIONS AND CLINICAL RELEVANCE

Integrating labeling and label-free approaches improve the confidence in quantitative profiling of pancreatic tissue proteome, which furthers the understanding of the dysregulated pathways and functional subnetworks associated with T1D pathogenesis and may aid to develop diagnostic and therapeutic strategies for T1D.

The Impact of Diabetes Mellitus on Cardiovascular Risk Onset in Children and Adolescents

The prevalence of diabetes mellitus is rising among children and adolescents worldwide. Cardiovascular diseases are the main cause of morbidity and mortality in diabetic patients. We review the impact of diabetes on establishing, during childhood and adolescence, the premises for cardiovascular diseases later in life. Interestingly, it seems that hyperglycemia is not the only factor that establishes an increased cardiovascular risk in adolescence. Other factors have been recognized to play a role in triggering the onset of latent cardiovascular diseases in the pediatric population. Among these cardiovascular risk factors, some are modifiable: glucose variability, hypoglycemia, obesity, insulin resistance, waist circumference, hypertension, dyslipidemia, smoking alcohol, microalbuminuria and smoking. Others are unmodifiable, such as diabetes duration and family history. Among the etiological factors, subclinical endothelial dysfunction represents one of the earliest key players of atherosclerosis and it can be detected during early ages in patients with diabetes. A better assessment of cardiovascular risk in pediatric population still represents a challenge for clinicians, and thus further efforts are required to properly identify and treat pediatric patients who may suffer from cardiovascular disease later in early adulthood.

Preclinical and clinical results regarding the effects of a plant-based antidiabetic formulation versus well established antidiabetic molecules

Diabetes mellitus (DM) is a complex syndrome with debilitating long-term complications, comprising alterations of carbohydrate, protein and lipid metabolisms, along increased oxidative stress and chronic low-grade inflammation. Diet management and plant-based formulations can improve the metabolic status of patients, being used as adjuvants of classic antidiabetic therapy. The purpose of our study was to evaluate the impact of a plant-based antidiabetic formulation (PBAF), containing Vaccinium myrtillus, Ribes nigrum, Rosa canina and Capsicum annuum, on the increased oxidative burden found in diabetes mellitus, comparing it with the effects of metformin and gliclazide. Firstly, we characterized the individual plant-derived components of this formulation and also assessed their in vitro radical scavenging capacity. We devised a preclinical study protocol to examine the impact of the PBAF, along metformin and gliclazide, on tissue histology as well as on the redox status of tissue, mitochondria, serum and serum lipoproteins of alloxan-induced diabetic Wistar rats. Subsequently, we assessed their long-term impact on the redox status of serum and isolated serum lipoproteins of type 2 DM (T2DM) patients, taking into consideration their cardiometabolic profile. In the preclinical stage, we found that PBAF was able to enhance total serum antioxidant defense, while metformin yielded the best results regarding the advanced glycation and protein/lipid oxidation of serum and of serum lipoproteins. The latter also improved overall serum redox status and HDL redox function. Also, antidiabetic treatment seemed to increase mitochondrial redox activity, without overturning overall tissue redox balance. Histologically, liver and brain tissues of treated diabetic rats were fairly similar to those of non-diabetic rats. In T2DM patients, the most striking results involved the effects on serum lipoproteins. The tested PBAF exerted protective antioxidant effects on low-density and, especially, on high density lipoproteins. We conclude that this formulation might constitute a good addition to the well-established pharmacological approach of DM, contributing to the reduction of overall oxidative burden.

A critical review of adverse effects to the kidney: mechanisms, data sources, and in silico tools to assist prediction

INTRODUCTION

The kidney is a major target for toxicity elicited by pharmaceuticals and environmental pollutants. Standard testing which often does not investigate underlying mechanisms has proven not to be an adequate hazard assessment approach. As such, there is an opportunity for the application of computational approaches that utilize multiscale data based on the Adverse Outcome Pathway (AOP) paradigm, coupled with an understanding of the chemistry underpinning the molecular initiating event (MIE) to provide a deep understanding of how structural fragments of molecules relate to specific mechanisms of nephrotoxicity. Aims covered: The aim of this investigation was to review the current scientific landscape related to computational methods, including mechanistic data, AOPs, publicly available knowledge bases and current in silico models, for the assessment of pharmaceuticals and other chemicals with regard to their potential to elicit nephrotoxicity. A list of over 250 nephrotoxicants enriched with, where possible, mechanistic and AOP-derived understanding was compiled. Expert opinion: Whilst little mechanistic evidence has been translated into AOPs, this review identified a number of data sources of in vitro, in vivo, and human data that may assist in the development of in silico models which in turn may shed light on the interrelationships between nephrotoxicity mechanisms.

Divergent antioxidant capacity of human islet cell subsets: A potential cause of beta-cell vulnerability in diabetes and islet transplantation

Background

Type 1 and Type 2 diabetes mellitus (T1DM and T2DM) are caused by beta(β)-cell loss and functional impairment. Identification of mechanisms of β-cell death and therapeutic interventions to enhance β-cell survival are essential for prevention and treatment of diabetes. Oxidative stress is a common feature of both T1DM and T2DM; elevated biomarkers of oxidative stress are detected in blood, urine and tissues including pancreas of patients with DM. Islet transplantation is a promising treatment for diabetes. However, exposure to stress (chemical and mechanical) and ischemia-reperfusion during isolation and transplantation causes islet loss by generation of reactive oxygen species (ROS). Human intracellular antioxidant enzymes and related molecules are essential defenses against ROS. Antioxidant enzyme levels including superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) have been shown to be low in islet cells. However, little is known about the expression and function of antioxidant enzymes within islet cell subsets. We evaluated the expression of the key antioxidant enzymes in β- and alpha(α)-cell and accessed effects of oxidative stress, islet isolation and transplantation on β/α-cell ratio and viability in human islets.

Methods

Human pancreata from T1DM, T2DM and non-diabetic deceased donors were obtained and analyzed by confocal microscopy. Isolated islets were (I) transplanted in the renal sub-capsular space of streptozotocin-induced diabetic nude mice (in vivo bioassay), or (II) exposed to oxidative (H₂O₂) and nitrosative (NO donor) stress for 24 hrs in vitro. The ratio, % viability and death of β- and α-cells, and DNA damage (8OHdG) were measured.

Results and conclusions

Catalase and GPX expression was much lower in β- than α-cells. The β/α-cell ratio fells significantly following islet isolation and transplantation. Exposure to oxidative stress caused a significantly lower survival and viability, with higher DNA damage in β- than α-cells. These findings identified the weakness of β-cell antioxidant capacity as a main cause of vulnerability to oxidative stress. Potential strategies to enhance β-cell antioxidant capacity might be effective in prevention/treatment of diabetes.

Role of the PI3K/AKT signalling pathway in apoptotic cell death in the cerebral cortex of streptozotocin-induced diabetic rats

Diabetes mellitus is associated with cognitive dysfunction. Numerous previous studies have shown that type 1 diabetes-induced hyperglycaemia causes structural brain damage, such as a decrease in whole-brain grey matter. The impact of diabetes mellitus on the cerebral cortex is poorly understood and requires further clarification. In the present study, diabetes was induced via an intraperitoneal injection of streptozotocin (50 mg/kg). Hematoxylin and eosin (H&E) staining was performed to detect the morphological changes in the cerebral cortex, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) staining was used to detect neuronal apoptosis and western blotting was performed to determine protein expression levels. Nine weeks after the induction of diabetes, the body weight was significantly lower and the blood glucose levels were significantly higher in the diabetic rats than in the control rats (P<0.05). H&E staining revealed nuclear chromatin condensation and cytoplasmic shrinkage in the cerebral cortex of the diabetic rats and TUNEL staining further indicated apoptotic changes in the cerebral cortex of the diabetic rats. The ratio of B-cell lymphoma 2 (Bcl-2) -associated X protein/Bcl-2 and the expression of cytochrome c and activated caspase-3 (cleaved caspase-3) were significantly increased, whereas the ratio of phosphorylated AKT/AKT was significantly decreased in the diabetic rats compared with that in the control rats (P<0.05). Taken together, these results suggested that diabetes mellitus may induce neuronal apoptosis in the cerebral cortex by downregulating AKT phosphorylation.

The nephrologist of tomorrow: towards a kidney-omic future

Omics refers to the collective technologies used to explore the roles and relationships of the various types of molecules that make up the phenotype of an organism. Systems biology is a scientific discipline that endeavours to quantify all of the molecular elements of a biological system. Therefore, it reflects the knowledge acquired by omics in a meaningful manner by providing insights into functional pathways and regulatory networks underlying different diseases. The recent advances in biotechnological platforms and statistical tools to analyse such complex data have enabled scientists to connect the experimentally observed correlations to the underlying biochemical and pathological processes. We discuss in this review the current knowledge of different omics technologies in kidney diseases, specifically in the field of pediatric nephrology, including biomarker discovery, defining as yet unrecognized biologic therapeutic targets and linking omics to relevant standard indices and clinical outcomes. We also provide here a unique perspective on the field, taking advantage of the experience gained by the large-scale European research initiative called "Systems Biology towards Novel Chronic Kidney Disease Diagnosis and Treatment" (SysKid). Based on the integrative framework of Systems biology, SysKid demonstrated how omics are powerful yet complex tools to unravel the consequences of diabetes and hypertension on kidney function.

Type 1 Diabetes and Dysfunctional Intestinal Homeostasis

Despite the relatively high frequency of gastrointestinal (GI) disorders in individuals with type 1 diabetes (T1D), termed diabetic enteropathy (DE), the pathogenic mechanisms of these disorders remain to be elucidated. While previous studies have assumed that DE is a manifestation of diabetic autonomic neuropathy, other contributing factors such as enteric hormones, inflammation, and microbiota were later recognized. More recently, the emerging role of intestinal stem cells (ISCs) in several GI diseases has led to a new understanding of DE. Given the absence of diagnostic methods and the lack of broadly efficacious therapeutic remedies in DE, targeting factors and pathways that control ISC homeostasis and are dysfunctional in DE may represent a new path for the detection and cure of DE.

Circulating IGF-I and IGFBP3 Levels Control Human Colonic Stem Cell Function and Are Disrupted in Diabetic Enteropathy

The role of circulating factors in regulating colonic stem cells (CoSCs) and colonic epithelial homeostasis is unclear. Individuals with long-standing type 1 diabetes (T1D) frequently have intestinal symptoms, termed diabetic enteropathy (DE), though its etiology is unknown. Here, we report that T1D patients with DE exhibit abnormalities in their intestinal mucosa and CoSCs, which fail to generate in vitro mini-guts. Proteomic profiling of T1D+DE patient serum revealed altered levels of insulin-like growth factor 1 (IGF-I) and its binding protein 3 (IGFBP3). IGFBP3 prevented in vitro growth of patient-derived organoids via binding its receptor TMEM219, in an IGF-I-independent manner, and disrupted in vivo CoSC function in a preclinical DE model. Restoration of normoglycemia in patients with long-standing T1D via kidney-pancreas transplantation or in diabetic mice by treatment with an ecto-TMEM219 recombinant protein normalized circulating IGF-I/IGFBP3 levels and reestablished CoSC homeostasis. These findings demonstrate that peripheral IGF-I/IGFBP3 controls CoSCs and their dysfunction in DE.

Membranous nephropathy and cerebellar degeneration with anti-GAD antibodies in type 2 diabetes mellitus

AIMS

To study the potential pathogenic significance of the coexistence of membranous nephropathy, cerebellar degeneration and anti-glutamic acid decarboxylase (GAD) autoantibodies in patients with diabetes.

METHODS

We performed a direct immunocytochemistry on human kidney slides, electron microscopy on human kidney biopsy, direct immunofluorescence on human kidney biopsy. Baboon and rat kidney cell lines were fractionated and subjected to western blotting with antibodies to GAD.

RESULTS

In this patient we demonstrate the presence of autoantibodies to GAD, which is highly enriched in podocytes plasma membrane and tubular cells of the kidney as well as sub-endothelial IgG and complement C3 deposits in the glomerular basement membrane (GBM).

CONCLUSIONS

We hypothesize the existence in this patient of a common autoimmune pathogenic mechanism with GAD as the autoantigenic determinant, underlying cerebellar degeneration and membranous nephropathy.

Explaining the increased mortality in type 1 diabetes

Despite large improvements in the management of glucose levels and in the treatment of cardiovascular risk factors, the mortality rate in individuals with type 1 diabetes (T1D) is still high. Recently, Lind et al found that T1D individuals with glycated hemoglobin levels of 6.9% or lower had a risk of death from any cause or from cardiovascular causes that is twice as high as the risk for matched controls. T1D is a chronic disease with an early onset (e.g., pediatric age) and thus in order to establish a clear correlation between death rate and the glycometabolic control, the whole history of glycemic control should be considered; particularly in the early years of diabetes. The switch from a normo- to hyperglycemic milieu in an individual with T1D in the pediatric age, represents a stressful event that may impact outcomes and death rate many years later. In this paper we will discuss the aforementioned issues, and offer our view on these findings, paying a particular attention to the several alterations occurring in the earliest phases of T1D and to the many factors that may be associated with the chronic history of T1D. This may help us to better understand the recently published death rate data and to develop future innovative and effective preventive strategies.

NETosis is induced by high glucose and associated with type 2 diabetes

AIMS

The role of neutrophils in diabetes and its complications is unclear. Upon challenge with microbes and inflammatory triggers, neutrophils release enzymes and nuclear material, forming neutrophils extracellular traps (NETs) and thereby dying by NETosis. We herein tested NET formation and NETosis products in high glucose and in the setting of type 2 diabetes (T2D).

METHODS

NETosis was assessed in vitro in cells exposed to 0, 5, 25 mM glucose and 25 mM mannitol, DMSO and PMA using immunofluorescence staining for elastase, DNA and chromatin. Single-cell morphometric analysis was used to detect enter of elastase in the nucleus and extrusion of nuclear material. Release of NETs was quantified by staining with Hoechst 33342. In 38 T2D and 38 age- and sex-matched non-diabetic individuals, we determined plasma elastase, mono- and oligonucleosomes and double-strand (ds) DNA, as circulating NETosis products.

RESULTS

NETosis was accurately reproduced in vitro: high (25 mM) glucose increased NETosis rate and release of NETs compared with 5 mM glucose and 25 mM mannitol. T2D patients showed increased plasma elastase, mono- and oligonucleosomes and dsDNA compared with non-diabetic control individuals. A positive correlation was found between HbA1c and mono- and oligonucleosomes, whereas dsDNA was correlated with the presence of nephropathy and cardiovascular disease. Serum IL-6 concentrations were higher in T2D compared with CTRL and correlated with serum dsDNA levels.

CONCLUSIONS

High glucose and hyperglycemia increase release of NETs and circulating markers of NETosis, respectively. This finding provides a link among neutrophils, inflammation and tissue damage in diabetes.

Glycemic Variability: Assessing Glycemia Differently and the Implications for Dietary Management of Diabetes

The primary therapeutic target for diabetes management is the achievement of good glycemic control, of which glycated hemoglobin (HbA1c) remains the standard clinical marker. However, glycemic variability (GV; the amplitude, frequency, and duration of glycemic fluctuations around mean blood glucose) is an emerging target for blood glucose control. A growing body of evidence supports GV as an independent risk factor for diabetes complications. Several techniques have been developed to assess and quantify intraday and interday GV. Additionally, GV can be influenced by several nutritional factors, including carbohydrate quality, quantity; and distribution; protein intake; and fiber intake. These factors have important implications for clinical nutrition practice and for optimizing blood glucose control for diabetes management. This review discusses the available evidence for GV as a marker of glycemic control and risk factor for diabetes complications. GV quantification techniques and the influence of nutritional considerations for diabetes management are also discussed.

Liver protein profiles in insulin receptor-knockout mice reveal novel molecules involved in the diabetes pathophysiology

Liver has a principal role in glucose regulation and lipids homeostasis. It is under a complex control by substrates such as hormones, nutrients, and neuronal impulses. Insulin promotes glycogen synthesis, lipogenesis, and lipoprotein synthesis and inhibits gluconeogenesis, glycogenolysis, and VLDL secretion by modifying the expression and enzymatic activity of specific molecules. To understand the pathophysiological mechanisms leading to metabolic liver disease, we analyzed liver protein patterns expressed in a mouse model of diabetes by proteomic approaches. We used insulin receptor-knockout (IR(-/-)) and heterozygous (IR(+/-)) mice as a murine model of liver metabolic dysfunction associated with diabetic ketoacidosis and insulin resistance. We evaluated liver fatty acid levels by microscopic examination and protein expression profiles by orthogonal experimental strategies using protein 2-DE MALDI-TOF/TOF and peptic nLC-MS/MS shotgun profiling. Identified proteins were then loaded into Ingenuity Pathways Analysis to find possible molecular networks. Twenty-eight proteins identified by 2-DE analysis and 24 identified by nLC-MS/MS shotgun were differentially expressed among the three genotypes. Bioinformatic analysis revealed a central role of high-mobility group box 1/2 and huntigtin never reported before in association with metabolic and related liver disease. A different modulation of these proteins in both blood and hepatic tissue further suggests their role in these processes. These results provide new insight into pathophysiology of insulin resistance and hepatic steatosis and could be useful in identifying novel biomarkers to predict risk for diabetes and its complications.

Knockout of the TauT gene predisposes C57BL/6 mice to streptozotocin-induced diabetic nephropathy

Diabetic nephropathy is the leading cause of end stage renal disease in the world. Although tremendous efforts have been made, scientists have yet to identify an ideal animal model that can reproduce the characteristics of human diabetic nephropathy. In this study, we hypothesize that taurine insufficiency is a critical risk factor for development of diabetic nephropathy associated with diabetes mellitus. This hypothesis was tested in vivo in TauT heterozygous (TauT^+/-) and homozygous (TauT^-/-) knockout in C57BL/6 background mice. We have shown that alteration of the TauT gene (also known as SLC6A6) has a substantial effect on the susceptibility to development of extensive diabetic kidney disease in both TauT^+/- and TauT^-/-mouse models of diabetes. These animals developed histological changes characteristic of human diabetic nephropathy that included glomerulosclerosis, nodular lesions, arteriosclerosis, arteriolar dilation, and tubulointerstitial fibrosis. Immunohistochemical staining of molecular markers of smooth muscle actin, CD34, Ki67 and collagen IV further confirmed these observations. Our results demonstrated that both homozygous and heterozygous TauT gene deletion predispose C57BL/6 mice to develop end-stage diabetic kidney disease, which closely replicates the pathological features of diabetic nephropathy in human diabetic patients.

Novel therapeutic and diagnostic management of heart transplant patients

Heart transplantation was performed for the first time 40 years ago and it is now universally considered the "gold standard" treatment for individuals suffering from end-stage heart failure. The increased understanding of the molecular mechanisms and of the role of the immune system in allograft rejection led to an overall improvement of graft survival, which is now around 10 years. The introduction of novel immunosuppressive drugs reduced the rate of acute allograft rejection but did not improve significantly the long-term graft survival. In addition, adverse effects (e.g. infections, cancer and renal failure) associated with immunosuppressive drugs are increasing over time and may affect post-transplantation outcomes. An immunosuppression-free protocol based on tolerance induction is the Holy Grail for heart transplant recipients, but it is still far beyond our reach. In this review, we discuss the landscape of immunological challenges that heart transplanted individuals face and we critically review the novel immunological approaches available to overcome these remaining issues. Some of the novel approaches, successfully tested in preclinical and clinical models, may lead to a prolongation of patient's and heart allograft survival.

GTP cyclohydrolase I gene polymorphisms are associated with endothelial dysfunction and oxidative stress in patients with type 2 diabetes mellitus

BACKGROUND

The genetic background of atherosclerosis in type 2 diabetes mellitus (T2DM) is complex and poorly understood. Studying genetic components of intermediate phenotypes, such as endothelial dysfunction and oxidative stress, may aid in identifying novel genetic components for atherosclerosis in diabetic patients.

METHODS

Five polymorphisms forming two haplotype blocks within the GTP cyclohydrolase 1 gene, encoding a rate limiting enzyme in tetrahydrobiopterin synthesis, were studied in the context of flow and nitroglycerin mediated dilation (FMD and NMD), intima-media thickness (IMT), and plasma concentrations of von Willebrand factor (vWF) and malondialdehyde (MDA).

RESULTS

Rs841 was associated with FMD (p = 0.01), while polymorphisms Rs10483639, Rs841, Rs3783641 (which form a single haplotype) were associated with both MDA (p = 0.012, p = 0.0015 and p = 0.003, respectively) and vWF concentrations (p = 0.016, p = 0.03 and p = 0.045, respectively). In addition, polymorphism Rs8007267 was also associated with MDA (p = 0.006). Haplotype analysis confirmed the association of both haplotypes with studied variables.

CONCLUSIONS

Genetic variation of the GCH1 gene is associated with endothelial dysfunction and oxidative stress in T2DM patients.

Novel therapeutic approaches for diabetic nephropathy and retinopathy

Diabetes mellitus is a chronic disease that in the long-term increases the microvascular and macrovascular degenerative complications thus being responsible for a large part of death associated with diabetes. During the years, while preventive care for diabetic patients has improved, the increase in the prevalence of diabetes worldwide is continuous. The detrimental effects of diabetes mellitus result in microvascular diseases, which recognize hyperglycemia as major determinant. A significant number of potential therapeutic targets for the treatment of diabetic microvascular complications have been proposed, but the encouraging results obtained in preclinical studies, have largely failed in clinical trials. Currently, the most successful strategy to prevent microvascular complications of diabetes is the intensive treatment of hyperglycemia or the normalization of glycometabolic control achieved with pancreatic and islet transplantation. In this review, we focus on the novel therapeutic targets to prevent the development and progression of diabetic nephropathy and retinopathy microvascular complications.

Novel immunological strategies for islet transplantation

Islet transplantation has been demonstrated to improve glycometabolic control, to reduce hypoglycemic episodes and to halt the progression of diabetic complications. However, the exhaustion of islet function and the side effects related to chronic immunosuppression limit the spread of this technique. Consequently, new immunoregulatory protocols have been developed, with the aim to avoid the use of a life-time immunosuppression. Several approaches have been tested in preclinical models, and some are now under clinical evaluation. The development of new small molecules and new monoclonal or polyclonal antibodies is continuous and raises the possibility of targeting new costimulatory pathways or depleting particular cell types. The use of stem cells and regulatory T cells is underway to take advantage of their immunological properties and to induce tolerance. Xenograft islet transplantation, although having severe problems in terms of immunological compatibility, could theoretically provide an unlimited source of donors; using pigs carrying human immune antigens has showed indeed promising results. A completely different approach, the use of encapsulated islets, has been developed; synthetic structures are used to hide islet alloantigen from the immune system, thus preserving islet endocrine function. Once one of these strategies is demonstrated safe and effective, it will be possible to establish clinical islet transplantation as a treatment for patients with type 1 diabetes long before the onset of diabetic-related complications.

Influencing factors of new-onset diabetes after a renal transplant and their effects on complications and survival rate

OBJECTIVE

To discuss the onset of and relevant risk factors for new-onset diabetes after a transplant (NODAT) in patients who survive more than 1 year after undergoing a renal transplant and the influence of these risk factors on complications and long-term survival.

METHOD

A total of 428 patients who underwent a renal transplant between January 1993 and December 2008 and were not diabetic before surgery were studied. The prevalence rate of and relevant risk factors for postoperative NODAT were analyzed on the basis of fasting plasma glucose (FPG) levels, and differences in postoperative complications and survival rates between patients with and without NODAT were compared.

RESULTS

The patients in this study were followed up for a mean of 5.65 ± 3.68 years. In total, 87 patients (20.3%) developed NODAT. Patients who converted from treatment with CSA to FK506 had increased prevalence rates of NODAT (P <0.05). Multi-factor analysis indicated that preoperative FPG level (odds ratio [OR]  =  1.48), age (OR  =  1.10), body mass index (OR  =  1.05), hepatitis C virus infection (OR  =  2.72), and cadaveric donor kidney (OR  =  1.18) were independent risk factors for NODAT (All P <0.05). Compared with the N-NODAT group, the NODAT group had higher prevalence rates (P < 0.05) of postoperative infection, hypertension, and dyslipidemia; in addition, the survival rate and survival time of the 2 groups did not significantly differ.

CONCLUSION

Among the patients who survived more than 1 year after a renal transplant, the prevalence rate of NODAT was 20.32%. Preoperative FPG level, age, body mass index, hepatitis C virus infection, and cadaveric donor kidney were independent risk factors for NODAT. Patients who converted from treatment with CSA to FK506 after a renal transplant had aggravated impairments in glycometabolism. Patients with NODAT were also more vulnerable to postoperative complications such as infection, hypertension, and hyperlipidemia.

Differential proteomic analysis of the pancreas of diabetic db/db mice reveals the proteins involved in the development of complications of diabetes mellitus

Type 2 diabetes mellitus is characterized by hyperglycemia and insulin-resistance. Diabetes results from pancreatic inability to secrete the insulin needed to overcome this resistance. We analyzed the protein profile from the pancreas of ten-week old diabetic db/db and wild type mice through proteomics. Pancreatic proteins were separated in two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and significant changes in db/db mice respect to wild type mice were observed in 27 proteins. Twenty five proteins were identified by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) and their interactions were analyzed using search tool for the retrieval of interacting genes/proteins (STRING) and database for annotation, visualization and integrated discovery (DAVID). Some of these proteins were Pancreatic α-amylase, Cytochrome b5, Lithostathine-1, Lithostathine-2, Chymotrypsinogen B, Peroxiredoxin-4, Aspartyl aminopeptidase, Endoplasmin, and others, which are involved in the metabolism of carbohydrates and proteins, as well as in oxidative stress, and inflammation. Remarkably, these are mostly endoplasmic reticulum proteins related to peptidase activity, i.e., they are involved in proteolysis, glucose catabolism and in the tumor necrosis factor-mediated signaling pathway. These results suggest mechanisms for insulin resistance, and the chronic inflammatory state observed in diabetes.

Role of podocyte B7-1 in diabetic nephropathy

Podocyte injury and resulting albuminuria are hallmarks of diabetic nephropathy, but targeted therapies to halt or prevent these complications are currently not available. Here, we show that the immune-related molecule B7-1/CD80 is a critical mediator of podocyte injury in type 2 diabetic nephropathy. We report the induction of podocyte B7-1 in kidney biopsy specimens from patients with type 2 diabetes. Genetic and epidemiologic studies revealed the association of two single nucleotide polymorphisms at the B7-1 gene with diabetic nephropathy. Furthermore, increased levels of the soluble isoform of the B7-1 ligand CD28 correlated with the progression to ESRD in individuals with type 2 diabetes. In vitro, high glucose conditions prompted the phosphatidylinositol 3 kinase-dependent upregulation of B7-1 in podocytes, and the ectopic expression of B7-1 in podocytes increased apoptosis and induced disruption of the cytoskeleton that were reversed by the B7-1 inhibitor CTLA4-Ig. Podocyte expression of B7-1 was also induced in vivo in two murine models of diabetic nephropathy, and treatment with CTLA4-Ig prevented increased urinary albumin excretion and improved kidney pathology in these animals. Taken together, these results identify B7-1 inhibition as a potential therapeutic strategy for the prevention or treatment of diabetic nephropathy.

The inflammatory status score including IL-6, TNF-α, osteopontin, fractalkine, MCP-1 and adiponectin underlies whole-body insulin resistance and hyperglycemia in type 2 diabetes mellitus

A state of subclinical systemic inflammation is characteristically present in obesity/insulin resistance and type 2 diabetes mellitus (T2DM). The aim of the study was to develop an integrated measure of the circulating cytokines involved in the subclinical systemic inflammation and evaluate its relation with whole-body insulin sensitivity and glucose metabolism in T2DM. T2DM patients (n = 17, M/F 13/4, age = 55.0 ± 1.7 years, BMI = 33.5 ± 1.5 kg/m(2), HbA(1c) = 7.7 ± 0.3%) and normal glucose-tolerant (NGT) subjects (n = 15, M/F 7/8, age = 49.1 ± 2.5 years, BMI = 31.8 ± 1.2 kg/m(2), HbA(1c) = 5.6 ± 0.1%) were studied in a cross-sectional design. Whole-body insulin sensitivity was quantified by the euglycemic clamp. Beta-cell function [disposition index (DI)] was calculated using insulin and glucose values derived from an oral glucose tolerance test and the euglycemic clamp. Body fat mass was evaluated by dual-energy X-ray absorptiometry. Plasma cytokine [TNF-α, IL-6, MCP-1, osteopontin, fractalkine and adiponectin] values were divided into quintiles. A score ranging from 0 (lowest quintile) to 4 (highest quintile) was assigned. The inflammatory score (IS) was the sum of each cytokine score from which adiponectin score was subtracted in each study subject. Inflammatory cytokine levels were all higher in T2DM. IS was higher in T2DM as compared to NGT (10.0 ± 1.1 vs. 4.8 ± 0.8; p < 0.001). IS positively correlated with fasting plasma glucose (r = 0.638, p < 0.001), 1-h plasma glucose (r = 0.483, p = 0.005), 2-h plasma glucose (r = 0.611, p < 0.001) and HbA1c (r = 0.469, p = 0.007). IS was inversely correlated with insulin sensitivity (r = -0.478, p = 0.006) and DI (r = -0.523, p = 0.002). IS did not correlate with BMI and body fat mass. IS was an independent predictor of fasting plasma glucose and had a high sensibility and sensitivity to predict insulin resistance (M/I < 4). A state of subclinical inflammation defined and quantifiable by inflammatory score including TNF-α, IL-6, MCP-1, osteopontin, fractalkine and adiponectin is associated with both hyperglycemia and whole-body insulin resistance in T2DM.

The role of nateglinide and repaglinide, derivatives of meglitinide, in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is one of the most common chronic diseases worldwide, presenting a great challenge to the public health systems due to high morbidity and mortality, because of frequent micro-/macro-vascular complications. Many treatment options are now available, with different efficacy as well as mechanisms of action to improve deranged glucose metabolism. We review some of the available data on derivatives of meglitinide, namely nateglinide and repaglinide. These two compounds increase insulin secretion by a mechanism similar to the one of sulfonylureas, but with a shorter half-life. Nateglinide and repaglinide, derivatives of meglitinides, have characteristic pharmacodynamic and pharmacokinetic properties that, together with their proposed mechanism of action, make them useful for type 2 diabetes mellitus, especially when used in combination therapy.

The current state of pancreas transplantation

For many patients with type 1 diabetes mellitus and selected patients with type 2 diabetes mellitus, a successful pancreas transplant is the only definitive long-term treatment that both restores euglycaemia without the risk of severe hypoglycaemia and prevents, halts or reverses secondary complications. These benefits come at the cost of major surgery and lifelong immunosuppression. Nevertheless, pancreas transplants are safe and effective, with patient survival rates currently >95% at 1 year and >88% at 5 years; graft survival rates are almost 85% at 1 year and >60% at 5 years. The estimated half-life of a pancreas graft is now 7-14 years. The improvements in graft survival are attributable to considerable reductions in technical failures and in immunologic graft losses. Pancreas recipients have reduced mortality compared with waiting candidates or patients with diabetes mellitus who undergo a kidney transplant alone. Pancreas transplants should be more frequently offered to nonuraemic patients with brittle diabetes mellitus to prevent the development of secondary diabetic complications and to avoid the need for a kidney transplant. Although the results of islet transplantation have also improved, islet recipients rarely maintain long-term insulin independence despite the use of multiple organ donor pancreases. Pancreas transplants and islet transplants should be considered complementary, not mutually exclusive, procedures that are chosen on the basis of the individual patient's surgical risk.

Follow-up of secondary diabetic complications after pancreas transplantation

PURPOSE OF REVIEW

Successful pancreas transplantation restores physiologic glycemic and metabolic control. Its effects on overall patient survival (especially for simultaneous pancreas-kidney transplantation) are clear-cut. We herein review the available literature to define the impact of pancreas transplantation on chronic complications of diabetes mellitus.

RECENT FINDINGS

With longer-term follow-up, wider patient populations, and more accurate investigational tools (clinical and functional tests, noninvasive imaging, histology, and molecular biology), growing data show that successful pancreas transplantation may slow the progression, stabilize, and even favor the regression of secondary complications of diabetes, both microvascular and macrovascular, in a relevant proportion of recipients.

SUMMARY

Patients who are referred for pancreas transplantation usually suffer from advanced chronic complications of diabetes, which have classically been deemed irreversible. A successful pancreas transplantation is often able to slow the progression, stabilize, and even reverse many microvascular and macrovascular complications of diabetes. Growing clinical evidence shows that the expected natural history of long-term diabetic complications can be significantly modified by successful pancreas transplantation.

Impaired tissue regeneration corresponds with altered expression of developmental genes that persists in the metabolic memory state of diabetic zebrafish

As previously reported by our laboratory, streptozocin-induced diabetes mellitus (DM) in adult zebrafish results in an impairment of tissue regeneration as monitored by caudal fin regeneration. Following streptozocin withdrawal, a recovery phase occurs to reestablish euglycemia, via pancreatic beta-cell regeneration. However, DM-associated impaired fin regeneration continues indefinitely in the metabolic memory (MM) state, allowing for subsequent molecular analysis of the underlying mechanisms of MM. This study focuses on elucidating the molecular basis that explains the DM-associated impaired fin regeneration and why it persists into the MM state with the aim of better understanding MM. Using a combination of microarray analysis and bioinformatics approaches, our study found that of the 14,900 transcripts analyzed, aberrant expression of 71 genes relating to tissue developmental and regeneration processes were identified in DM fish and the altered expression of these 71 genes persisted in MM fish. Key regulatory genes of major development and signal transduction pathways were identified among this group of 71. The aberrant expression of key regulatory genes in the DM state that persist into the MM state provides a plausible explanation on how hyperglycemia induced impaired fin regeneration in the adult zebrafish DM/MM model.

Protein and peptide biomarkers in organ transplantation

Organ transplantation is the optimal treatment choice for end-stage organ failure in pediatric patients. The ideal maintenance of a transplanted organ requires efficient monitoring tools and an effective individualized post-transplant treatment plan. Currently available post-transplant monitoring options are not ideal because of their invasiveness or their lack of sensitivity and specificity when providing an accurate assessment of transplant injury. Current research on proteins and peptides, including mass spectrometry-based proteomics, can identify novel surrogate protein and peptide biomarkers that can assist in monitoring the graft in order to correctly assess the status of the transplanted organ. In this article, we have critically reviewed current relevant literature to highlight the importance of protein and peptide biomarkers in the field of pediatric organ transplantation, the status of research findings in the field of protein and peptide biomarkers in different organ transplantation and factors that impact and inhibit the progression of protein biomarker discovery in the field of solid-organ transplantation in pediatrics.

Reduction of oxidative stress and inflammation by blunting daily acute glucose fluctuations in patients with type 2 diabetes: role of dipeptidyl peptidase-IV inhibition

OBJECTIVE

Evaluate the effects of two dipeptidyl peptidase-IV (DPP-4) inhibitors, sitagliptin and vildagliptin, known to have different efficacy on mean amplitude of glycemic excursions (MAGE), on oxidative stress, and on systemic inflammatory markers in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A prospective, randomized, open-label PROBE design (parallel group with a blinded end point) study was performed in 90 patients with type 2 diabetes inadequately controlled by metformin. The study assigned 45 patients to receive sitagliptin (100 mg once daily; sitagliptin group) and 45 patients to receive vildagliptin (50 mg twice daily; vildagliptin group) for 12 weeks. MAGE, evaluated during 48 h of continuous subcutaneous glucose monitoring, allowed an assessment of daily glucose fluctuations at baseline and after 12 weeks in all patients. Assessment of oxidative stress (nitrotyrosine) and systemic levels of inflammatory markers interleukin (IL)-6 and IL-18 was performed at baseline and after 12 weeks in all patients.

RESULTS

HbA(1c), fasting and postprandial glucose, MAGE, and inflammatory and oxidative stress markers were similar between the groups at baseline. After 12 weeks, MAGE (P < 0.01) was lower in the vildagliptin group than in the sitagliptin group. After treatment, HbA(1c) and postprandial glucose evidenced similar changes between the groups (P = NS). Vildagliptin treatment was associated with a stronger decrease in nitrotyrosine (P < 0.01), IL-6 (P < 0.05), and IL-18 (P < 0.05) than sitagliptin treatment. Nitrotyrosine and IL-6 changes significantly correlated with changes in MAGE but not in fasting glucose and HbA(1c).

CONCLUSIONS

MAGE reduction is associated with reduction of oxidative stress and markers of systemic inflammation in type 2 diabetic patients. These effects were greater in the vildagliptin group than in the sitagliptin group.

Recent advances in biomarker discovery in solid organ transplant by proteomics

The identification and clinical use of more sensitive and specific biomarkers in the field of solid organ transplantation is an urgent need in medicine. Solid organ transplantation has seen improvements in the short-term survival of transplanted organs due to recent advancements in immunosuppressive therapy. However, the currently available methods of allograft monitoring are not optimal. Recent advancements in assaying methods for biomolecules such as genes, mRNA and proteins have helped to identify surrogate biomarkers that can be used to monitor the transplanted organ. These high-throughput 'omic' methods can help researchers to significantly speed up the identification and the validation steps, which are crucial factors for biomarker discovery efforts. Still, the progress towards identifying more sensitive and specific biomarkers remains a great deal slower than expected. In this article, we have evaluated the current status of biomarker discovery using proteomics tools in different solid organ transplants in recent years. This article summarizes recent reports and current status, along with the hurdles in efficient biomarker discovery of protein biomarkers using proteomics approaches. Finally, we will touch upon personalized medicine as a future direction for better management of transplanted organs, and provide what we think could be a recipe for success in this field.

Prospectively determined impact of type 1 diabetes on brain volume during development

OBJECTIVE

The impact of type 1 diabetes mellitus (T1DM) on the developing central nervous system is not well understood. Cross-sectional, retrospective studies suggest that exposure to glycemic extremes during development is harmful to brain structure in youth with T1DM. However, these studies cannot identify brain regions that change differentially over time depending on the degree of exposure to glycemic extremes.

RESEARCH DESIGN AND METHODS

We performed a longitudinal, prospective structural neuroimaging study of youth with T1DM (n = 75; mean age = 12.5 years) and their nondiabetic siblings (n = 25; mean age = 12.5 years). Each participant was scanned twice, separated by 2 years. Blood glucose control measurements (HbA(1c), glucose meter results, and reports of severe hypoglycemia) were acquired during the 2-year follow-up. Sophisticated image registration algorithms were performed, followed by whole brain and voxel-wise statistical analyses of the change in gray and white matter volume, controlling for age, sex, and age of diabetes onset.

RESULTS

The T1DM and nondiabetic control (NDC) sibling groups did not differ in whole brain or voxel-wise change over the 2-year follow-up. However, within the T1DM group, participants with more hyperglycemia had a greater decrease in whole brain gray matter compared with those with less hyperglycemia (P < 0.05). Participants who experienced severe hypoglycemia had greater decreases in occipital/parietal white matter volume compared with those with no severe hypoglycemia (P < 0.05) and compared with the NDC sibling group (P < 0.05).

CONCLUSIONS

These results demonstrate that within diabetes, exposure to hyperglycemia and severe hypoglycemia may result in subtle deviation from normal developmental trajectories of the brain.