Influence of carnosine supplementation on disease progression in a rat model of focal segmental glomerulosclerosis.

In diabetic kidney disease models, carnosine supplementation ameliorates renal pathology, but its influence in other renal pathologies is less explored. Thus, using the transgenic rat TGRNeph-hAT1 with sex-dependent focal segmental glomerulosclerosis, we first tested whether renal expression levels of carnosine system components correlate with disease. Next, we assessed whether carnosine supplementation in male rats improves pathology.

Serum Carnosinase 1 Is Not Associated with Insulin Resistance or Glucose Metabolism in a Type 1 Diabetes Cohort.

: Preclinical studies suggest that the deleterious effect of a high serum carnosinase 1 (CN1) concentration is attributed to its adverse effects on insulin sensitivity and glucose metabolism. However, there is little evidence for a modulating role of CN1 in glucose metabolism in humans. : We measured serum CN1 concentration in an observational type 1 diabetes cohort of 172 patients in whom glucose variability (MAGE, MODD, SD of individual blood glucose, mean, and CV) was recorded by blinded continuous glucose monitoring for 5-7 days.

Serum carnosinase 1, an early indicator for incident microalbuminuria in type 1 diabetes.

Aims: Carnosinase (CN1) polymorphisms have been linked to diabetic kidney disease (DKD), as CN1 degrades dipeptides which scavenge oxidative metabolites and prevent the formation of advanced glycation end-products. In this work, we studied the association between serum CN1, the systemic redox status and long-term renal outcome in type 1 diabetes.

Methods: Serum CN1 was measured in a prospective type 1 diabetes cohort ( = 218) with a 16-year follow-up.

Gene regulation for inflammation and inflammation resolution differs between umbilical arterial and venous endothelial cells.

Systemic inflammation affects the whole vasculature, yet whether arterial and venous endothelial cells differ in their abilities to mediate inflammation and to return to homeostasis after an inflammatory stimulus has not been addressed thoroughly. We assessed gene-expression profiles in isolated endothelial cells from human umbilical arteries (HUAEC) or veins (HUVEC) under basal conditions, after TNF-α stimulation and various time points after TNF-α removal to allow reinstatement of homeostasis. TNF-α regulates the expression of different sets of transcripts that are significantly changed only in HUAEC, only in HUVEC or changed in both.

Lipopolysaccharide Tolerance in Human Primary Monocytes and Polarized Macrophages.

Innate immune memory allows macrophages to adequately respond to pathogens to which they have been pre-exposed. To what extent different pattern recognition receptors, cytokines and resolution signals influence innate immune memory needs further elucidation. The present study assessed whether lipopolysaccharide (LPS) tolerance in monocytes and macrophages is affected by these factors.

Association Between Serum Carnosinase Concentration and Activity and Renal Function Impairment in a Type-2 Diabetes Cohort.

Genetic studies have identified associations of carnosinase 1 (CN1) polymorphisms with diabetic kidney disease (DKD). However, CN1 levels and activities have not been assessed as diagnostic or prognostic markers of DKD in cohorts of patients with type 2 diabetes (T2D). We established high-throughput, automated CN1 activity and concentration assays using robotic systems.

Influence of carnosine and carnosinase-1 on diabetes-induced afferent arteriole vasodilation: implications for glomerular hemodynamics.

Dysregulation in glomerular hemodynamics favors hyperfiltration in diabetic kidney disease (DKD). Although carnosine supplementation ameliorates features of DKD, its effect on glomerular vasoregulation is not known. We assessed the influence of carnosine and carnosinase-1 (CN1) on afferent glomerular arteriole vasodilation and its association with glomerular size, hypertrophy, and nephrin expression in diabetic BTBR mice.

Concurrent stimulation of monocytes with CSF1 and polarizing cytokines reveals phenotypic and functional differences with classical polarized macrophages.

In atherosclerotic lesions, macrophages are exposed to CSFs and various microenvironmental cues, which ultimately drive their polarization state. We studied the expression of different CSFs in artery specimen and cultured vascular cells and assessed whether concurrent stimulation (CS) of monocytes with CSF1 and polarizing cytokines generated macrophages (CSM1 and CSM2) that were phenotypically and functionally different from classically polarized M1 and M2 macrophages. We also assessed the influence of acetylsalicylic acid (ASA) on the capacity of polarized macrophages to stimulate T-cell proliferation.

ET-CORM Mediated Vasorelaxation of Small Mesenteric Arteries: Involvement of Kv7 Potassium Channels.

Although the vasoactive properties of carbon monoxide (CO) have been extensively studied, the mechanism by which CO mediates vasodilation is not completely understood. Through-out published studies on CO mediated vasodilation there is inconsistency on the type of K-channels that are activated by CO releasing molecules (CORMs). Since the vasorelaxation properties of enzyme triggered CORMs (ET-CORMs) have not been studied thus far, we first assessed if ET-CORMs can mediate vasodilation of small mesenteric arteries and subsequently addressed the role of soluble guanylate cyclase (sGC) and that of K-channels herein.

Urinary Carnosinase-1 Excretion is Associated with Urinary Carnosine Depletion and Risk of Graft Failure in Kidney Transplant Recipients: Results of the TransplantLines Cohort Study.

Carnosine affords protection against oxidative and carbonyl stress, yet high concentrations of the carnosinase-1 enzyme may limit this. We recently reported that high urinary carnosinase-1 is associated with kidney function decline and albuminuria in patients with chronic kidney disease. We prospectively investigated whether urinary carnosinase-1 is associated with a high risk for development of late graft failure in kidney transplant recipients (KTRs).

Meat intake and risk of mortality and graft failure in kidney transplant recipients.

Background: It is unknown whether meat intake is beneficial for long-term patient and graft survival in kidney transplant recipients (KTR).

Objectives: We first investigated the association of the previously described meat intake biomarkers 1-methylhistidine and 3-methylhistidine with intake of white and red meat as estimated from a validated food frequency questionnaire (FFQ). Second, we investigated the association of the meat intake biomarkers with long-term outcomes in KTR.

Methylglyoxal induces p53 activation and inhibits mTORC1 in human umbilical vein endothelial cells.

Methylglyoxal (MGO), a precursor of advanced glycation end products (AGEs), is regarded as a pivotal mediator of vascular damage in patients with diabetes. We have previously reported that MGO induces transcriptional changes compatible with p53 activation in cultured human endothelial cells. To further substantiate this finding and to explore the underlying mechanisms and possible consequences of p53 activation, we aimed (1) to provide direct evidence for p53 activation in MGO-treated human umbilical vein endothelial cells (HUVECs), (2) to assess putative mechanisms by which this occurs, (3) to analyze down-stream effects on mTOR and autophagy pathways, and (4) to assess the potential benefit of carnosine herein.

Rat donor lung quality deteriorates more after fast than slow brain death induction.

Donor brain death (BD) is initiated by an increase in intracranial pressure (ICP), which subsequently damages the donor lung. In this study, we investigated whether the speed of ICP increase affects quality of donor lungs, in a rat model for fast versus slow BD induction. Rats were assigned to 3 groups: 1) control, 2) fast BD induction (ICP increase over 1 min) or 3) slow BD induction (ICP increase over 30 min).

Human carnosinase 1 overexpression aggravates diabetes and renal impairment in BTBR mice.

Objective: To assess the influence of serum carnosinase (CN1) on the course of diabetic kidney disease (DKD).

Methods: hCN1 transgenic (TG) mice were generated in a BTBR genetic background to allow the spontaneous development of DKD in the presence of serum carnosinase. The influence of serum CN1 expression on obesity, hyperglycemia, and renal impairment was assessed.

Serum Carnosinase-1 and Albuminuria Rather than the Genotype Correlate with Urinary Carnosinase-1 in Diabetic and Nondiabetic Patients with Chronic Kidney Disease.

Background: Carnosinase-1 (CN-1) can be detected in 24 h urine of healthy individuals and patients with type 2 diabetes (T2DM). We aimed to assess whether urinary CN-1 is also reliably measured in spot urine and investigated its association with renal function and the albumin/creatinine ratio (ACR). We also assessed associations between the (CTG) genotype and CN-1 concentrations in serum and urine.

N-Octanoyl-Dopamine inhibits cytokine production in activated T-cells and diminishes MHC-class-II expression as well as adhesion molecules in IFNγ-stimulated endothelial cells.

IFNγ enhances allograft immunogenicity and facilitates T-cell mediated rejection. This may cause interstitial fibrosis and tubular atrophy (IFTA), contributing to chronic allograft loss. We assessed if inhibition of T-cell activation by N-octanoyl dopamine (NOD) impairs adherence of activated T-cells to endothelial cells and the ability of activated T-cells to produce IFNγ.

The Cholinergic Anti-Inflammatory Pathway as a Conceptual Framework to Treat Inflammation-Mediated Renal Injury.

Background: The cholinergic anti-inflammatory pathway, positioned at the interface of the nervous and immune systems, is the efferent limb of the "inflammatory reflex" which mainly signals through the vagus nerve. As such, the brain can modulate peripheral inflammatory responses by the activation of vagal efferent fibers. Importantly, immune cells in the spleen express most cholinergic system components such as acetylcholine (ACh), choline acetyltransferase, acetylcholinesterase, and both muscarinic and nicotinic ACh receptors, making communication between both systems possible.

Methylglyoxal down-regulates the expression of cell cycle associated genes and activates the p53 pathway in human umbilical vein endothelial cells.

Although methylglyoxal (MGO) has emerged as key mediator of diabetic microvascular complications, the influence of MGO on the vascular transcriptome has not thoroughly been assessed. Since diabetes is associated with low grade inflammation causing sustained nuclear factor-kappa B (NF-κB) activation, the current study addressed 1) to what extent MGO changes the transcriptome of human umbilical vein endothelial cells (HUVECs) exposed to an inflammatory milieu, 2) what are the dominant pathways by which these changes occur and 3) to what extent is this affected by carnosine, a putative scavenger of MGO. Microarray analysis revealed that exposure of HUVECs to high MGO concentrations significantly changes gene expression, characterized by prominent down-regulation of cell cycle associated genes and up-regulation of heme oxygenase-1 (HO-1).

Carnosinase concentration, activity, and CNDP1 genotype in patients with type 2 diabetes with and without nephropathy.

This study assessed if serum carnosinase (CNDP1) activity and concentration in patients with type 2 diabetes mellitus (T2D) with diabetic nephropathy (DN) differs from those without nephropathy. In a cross-sectional design 127 patients with T2D with DN ((CTG) homozygous patients n = 45) and 145 patients with T2D without nephropathy ((CTG) homozygous patients n = 47) were recruited. Univariate and multivariate regression analyses were performed to predict factors relevant for serum CNDP1 concentration.

Donor Dopamine Does Not Affect Liver Graft Survival: Evidence of Safety From a Randomized Controlled Trial.

Treatment of donation after brain death (DBD) donors with low-dose dopamine improves the outcomes after kidney and heart transplantation. This study investigates the course of liver allografts from multiorgan donors enrolled in the randomized dopamine trial between 2004 and 2007 (clinicaltrials.gov identifier: NCT00115115).

Impact of Donor Core Body Temperature on Graft Survival After Heart Transplantation.

Background: A previous donor intervention trial found that induction of mild therapeutic hypothermia in the brain-dead donor reduced the dialysis requirement after kidney transplantation. Consequences on the performance of cardiac allografts after transplantation were not explored to date.

Methods: Cohort study investigating 3-year heart allograft survival according to spontaneous core body temperature (CBT) assessed on the day of organ procurement.

Detection of carnosinase-1 in urine of healthy individuals and patients with type 2 diabetes: correlation with albuminuria and renal function.

Low serum carnosinase (CN-1) concentrations are associated with low risk for development of diabetic nephropathy (DN) in patients with type 2 diabetes (T2D). Although CN-1 is expressed in the kidney, urinary CN-1 (CNU) excretion and its pathological relevance in patients with T2D have not been investigated to date. The present study therefore assessed the extent of CNU excretion in healthy subjects (n = 243) and in patients with T2D (n = 361) enrolled in the DIAbetes and LifEstyle Cohort Twente-1 (DIALECT-1) in relation to functional renal parameters.

Identification and characterisation of carnostatine (SAN9812), a potent and selective carnosinase (CN1) inhibitor with in vivo activity.

Carnosinase 1 (CN1) has been postulated to be a susceptibility factor for developing diabetic nephropathy (DN). Although its major substrate, carnosine, is beneficial in rodent models of DN, translation of these findings to humans has been hampered by high CN1 activity in human serum resulting in rapid degradation of carnosine. To overcome this hurdle, we screened a protease-directed small-molecule library for inhibitors of human recombinant CN1.