MCP-1and IL-1β expression in the myocardia of two young patients with Type 1 diabetes mellitus and fatal diabetic ketoacidosis

The Role of NLRP3 Inflammasome Signaling on Arrhythmias in Diabetes

Diabetes is a significant risk factor for arrhythmias. However, the pathophysiology of diabetes-related arrhythmias still needs to be elucidated, presumably associated with structural and electrical remodeling. There is growing evidence that inflammation and arrhythmias are intimately associated, which has spurred significant interest in exploring the regulatory links in diabetes. Recent research findings have revealed a vital role for the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling, and facilitated the occurrence of arrhythmias in diabetes, including NLRP3 inflammasome activation by multiple stressors and its downstream cytokines, interleukin-1β (IL-1β) and interleukin-18 (IL-18). This narrative review aims to summarize the complex interaction between NLRP3 inflammasomes signaling and diabetes-related arrhythmias. Articles regarding the role of NLRP3 inflammasome in diabetes-related arrhythmias and relevant mechanisms were selected. Relevant articles were selected from PubMed. The search terms were "NLRP3 inflammasome" and "diabetes" and "arrhythmia". Important references from selected articles were also retrieved. The role of NLRP3 inflammasome signaling in diabetes-induced arrhythmias may provide a new option for the prevention and treatment diabetes-related arrhythmias.

SGLT2 Inhibition by Dapagliflozin Attenuates Diabetic Ketoacidosis in Mice with Type-1 Diabetes

BACKGROUND

SGLT2 inhibitors increase plasma ketone concentrations. It has been suggested that insulinopenia, along with an increase in the counter-regulatory hormones epinephrine, corticosterone, glucagon and growth hormone, can induce ketoacidosis, especially in type-1 diabetes (T1DM). Dehydration precipitates SGLT2 inhibitor-induced ketoacidosis in type-2 diabetes. We studied the effects of dapagliflozin and water deprivation on the development of ketoacidosis and the associated signaling pathways in T1DM mice.

METHODS

C57BL/6 mice were fed a high-fat diet. After 7 days, some mice received intraperitoneal injection of streptozocin + alloxan (STZ/ALX). The treatment groups were control + water at lib; control + dapagloflozin + water at lib; control + dapagloflozin + water deprivation; STZ/ALX + water at lib; STZ/ALX + water deprivation; STZ/ALX + dapagloflozin + water at lib; STZ/ALX + dapagloflozin + water deprivation. Dapagliflozin was given for 7 days. In the morning of day 18, food was removed, and water was removed in the water deprivation groups. ELISA, rt-PCR, and immunoblotting were used to assess blood, heart, liver, white and brown adipose tissues.

RESULTS

The T1DM mice had ketoacidosis even without water deprivation. Water deprivation increased plasma levels of β-hydroxybutyrate, acetoacetate, corticosterone, and epinephrine and reduced the levels of adiponectin in T1DM mice. Interleukin (IL) 1β, IL-6, IL-8, and TNFα were also increased in the T1DM mice with water deprivation. Dapagliflozin attenuated the changes in the T1DM mice without and with water deprivation. Likewise, water deprivation increased the activation of the inflammasome in the heart, liver, and white fat of the T1DM mice and dapagliflozin attenuated these changes. Dapagliflozin reduced the mRNA levels of glucagon receptors in the liver and the increase in GPR109a in white and brown fat. In the liver, dapagliflozin increased AMPK phosphorylation, and attenuated the phosphorylation of TBK1 and the activation of NFκB.

CONCLUSIONS

Dapagliflozin reduced ketone body levels and attenuated the activation of NFκB and the activation of the inflammasome in T1DM mice with ketoacidosis.

Tryptophan, kynurenine pathway, and diabetic ketoacidosis in type 1 diabetes

Diabetic ketoacidosis (DKA) is a serious complication of complete insulin deficiency and insulin resistance in Type 1 diabetes (T1D). This results in the body producing high levels of serum ketones in an attempt to compensate for the insulin deficiency and decreased glucose utilization. DKA's metabolic and immunologic dysregulation results in gradual increase of systemic and cerebral oxidative stress, along with low grade systemic and cerebral inflammation and the development of pretreatment subclinical BE. During treatment the early progression of oxidative stress and inflammation is hypothesized to advance the possibility of occurrence of crisis of clinical brain edema (BE), which is the most important cause of morbidity and mortality in pediatric DKA. Longitudinal neurocognitive studies after DKA treatment show progressive and latent deficits of cognition and emphasize the need for more effective DKA treatment of this long-standing conundrum of clinical BE, in the presence of systemic osmotic dehydration, metabolic acidosis and immune dysregulation. Candidate biomarkers of several systemic and neuroinflammatory pathways prior to treatment also progress during treatment, such as the neurotoxic and neuroprotective molecules in the well-recognized tryptophan (TRP)/kynurenine pathway (KP) that have not been investigated in DKA. We used LC-MS/MS targeted mass spectrometry analysis to determine the presence and initiation of the TRP/KP at three time points: A) 6-12 hours after initiation of treatment; B) 2 weeks; and C) 3 months following DKA treatment to determine if they might be involved in the pathogenesis of the acute vasogenic complication of DKA/BE. The Trp/KP metabolites TRP, KYN, quinolinic acid (QA), xanthurnenic acid (XA), and picolinic acid (PA) followed a similar pattern of lower levels in early treatment, with subsequent increases. Time point A compared to Time points B and C were similar to the pattern of sRAGE, lactate and pyruvic acid. The serotonin/melatonin metabolites also followed a similar pattern of lower quantities at the early stages of treatment compared to 3 months after treatment. In addition, glutamate, n-acetylglutamate, glutamine, and taurine were all lower at early treatment compared to 3 months, while the ketones 3-hydroxybutaric acid and acetoacetate were significantly higher in the early treatment compared to 3 months. The two major fat metabolites, L-carnitine and acetyl-L-carnitine (ALC) changed inversely, with ALC significantly decreasing at 2 weeks and 3 months compared to the early stages of treatment. Both anthranilic acid (AA) and 3-OH-anthranilic acid (3OH-AA) had overall higher levels in the early stages of treatment (A) compared to Time points (B and C). Interestingly, the levels of AA and 3OH-AA early in treatment were higher in Caucasian females compared to African American females. There were also differences in the metabolite levels of QA and kynurenic acid (KA) between genders and between races that may be important for further development of custom targeted treatments. We hypothesize that the TRP/KP, along with the other inflammatory pathways, is an active participant in the metabolic and immunologic pathogenesis of DKA's acute and chronic insults.

Interleukin 1-beta is Linked to Chronic Low-Grade Inflammation and Cardiovascular Risk Factors in Overweight Adolescents

AIM

We hypothesized that IL-1β concentrations are augmented in overweight adolescents, who do not display metabolic syndrome. Additionally, we aimed to correlate the IL-1β concentrations with several established risk factors for CVD.

METHODS

Overweight or control subjects, aging from 14-18 years, were classified according to their adjusted body mass index and evaluated for biochemical and anthropometric parameters. The proinflammatory cytokine IL-1β was assessed in the serum.

RESULTS

Increased body fat percentage, waist circumference, triglycerides, total cholesterol, Very Low-Density Lipoprotein (VLDL) cholesterol, Low-Density Lipoprotein (LDL) cholesterol, Castelli I index, IL-1β, and IL-8 levels, were observed in overweight adolescents. No differences were observed in systolic blood pressure, diastolic blood pressure, glucose or High-Density Lipoprotein (HDL) cholesterol. Positive correlations between IL-1β with anthropometric and or biochemical parameters were found.

CONCLUSION

In conclusion, increased IL-1β levels correlate to dyslipidemic factors and may further support low-grade inflammation. IL-1β may further predict the early onset of cardiovascular disease in this population, taking into consideration its important regulatory role.

Soluble Receptor for Glycation End-products Concentration Increases Following the Treatment of Severe Diabetic Ketoacidosis

OBJECTIVE

To determine the time relationships of soluble receptor for glycation end-products (sRAGE), [a decoy of the advanced glycation end-products (AGE)-RAGE axis] and D-lactate, (a metabolite of methylglyoxal) in the inflammatory response to diabetic ketoacidosis (DKA).

METHODS

Sixteen children and adolescents with type 1 diabetes (T1D) had blood samples obtained, 6-12 hours into treatment, at three weeks and three months post start of treatment. sRAGE and D-lactate concentrations at three months were considered baseline. Expression of RAGE was investigated in the myocardium of a newly diagnosed and untreated young person with fatal T1D/DKA.

RESULTS

sRAGE 6-12 hours after the start of treatment was 39% lower than the values at two weeks (p=0.0036) and at three months (p=0.0023) post treatment. D-lactate was higher during treatment than at three weeks (p=0.04) and at three months (p=0.035).

CONCLUSION

sRAGE concentration was decreased during treatment, compared to concentrations at two weeks and three months after treatment. The increased D-lactate during treatment was in keeping with the known increase in dicarbonyls at this time. The finding of RAGE expression in a young myocardium prior to DKA treatment suggested cardiovascular inflammation pre-treatment and at a young age.

Spleen tyrosine kinase‑induced JNK‑dependent NLRP3 activation is involved in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a leading contributor to the increased morbidity and mortality rates associated with diabetes. Persistent inflammation has previously been reported to be involved in the pathogenesis of DCM. However, the exact underlying molecular mechanisms remain to be fully elucidated. In the present study, the role of spleen tyrosine kinase (Syk) and c‑Jun N‑terminal kinase (JNK) in NLR family pyrin domain‑containing 3 (NLRP3 inflammasome) activation in DCM were investigated in vivo and in vitro. Streptozotocin (65 mg/kg) was injected intraperitoneally into Sprague‑Dawley rats to induce a rat model of diabetes. Neonatal rat cardiomyocytes and H9c2 cells were cultured to detect the expression of JNK, NLRP3 and its associated downstream molecules, following treatment with Syk/JNK inhibitor or Syk/JNK‑small interfering (si)RNA in high glucose (HG) conditions. It was revealed that the protein and mRNA expression levels of phospho (p)‑Syk, p‑JNK, NLRP3 and its associated downstream molecules, including interleukin (IL)‑1β, were upregulated in vivo and in vitro. The JNK inhibitor significantly decreased the expression of NLRP3 and its downstream molecules in neonatal rat cardiomyocytes and H9c2 cells treated with HG. Furthermore, Syk‑siRNA and the Syk inhibitor markedly inhibited the HG‑induced activation of JNK, followed by the downregulation of NLRP3 and its downstream molecules at the mRNA and protein levels in cells. Therefore, it was demonstrated that the HG‑induced activation of NLRP3 was mediated by the activation of Syk/JNK, which subsequently increased the protein expression levels of mature IL‑1β, suggesting that the Syk/JNK/NLRP3 signaling pathway serves a critical role in the pathogenesis of DCM.

IL-1β Inhibition in Cardiovascular Complications Associated to Diabetes Mellitus

Diabetes mellitus (DM) is a chronic disease that affects nowadays millions of people worldwide. In adults, type 2 diabetes mellitus (T2DM) accounts for the majority of all diagnosed cases of diabetes. The course of the T2DM is characterized by insulin resistance and a progressive loss of β-cell mass. DM is associated with a number of related complications, among which cardiovascular complications and atherosclerosis are the main cause of morbidity and mortality in patients suffering from the disease. DM is acknowledged as a low-grade chronic inflammatory state characterized by the over-secretion of pro-inflammatory cytokines, including interleukin (IL)-1β, which reinforce inflammatory signals thus contributing to the development of complications. In this context, the pharmacological approaches to treat diabetes should not only correct hyperglycaemia, but also attenuate inflammation and prevent the development of metabolic and cardiovascular complications. Over the last years, novel biological drugs have been developed to antagonize the pathophysiological actions of IL-1β. The drugs currently used in clinical practice are anakinra, a recombinant form of the naturally occurring IL-1 receptor antagonist, the soluble decoy receptor rilonacept and the monoclonal antibodies canakinumab and gevokizumab. This review will summarize the main experimental and clinical findings obtained with pharmacological IL-1β inhibitors in the context of the cardiovascular complications of DM, and discuss the perspectives of IL-1β inhibitors as novel therapeutic tools for treating these patients.

Macrophage-dependent IL-1β production induces cardiac arrhythmias in diabetic mice

Diabetes mellitus (DM) encompasses a multitude of secondary disorders, including heart disease. One of the most frequent and potentially life threatening disorders of DM-induced heart disease is ventricular tachycardia (VT). Here we show that toll-like receptor 2 (TLR2) and NLRP3 inflammasome activation in cardiac macrophages mediate the production of IL-1β in DM mice. IL-1β causes prolongation of the action potential duration, induces a decrease in potassium current and an increase in calcium sparks in cardiomyocytes, which are changes that underlie arrhythmia propensity. IL-1β-induced spontaneous contractile events are associated with CaMKII oxidation and phosphorylation. We further show that DM-induced arrhythmias can be successfully treated by inhibiting the IL-1β axis with either IL-1 receptor antagonist or by inhibiting the NLRP3 inflammasome. Our results establish IL-1β as an inflammatory connection between metabolic dysfunction and arrhythmias in DM.

Parenchymal and Stromal Cells Contribute to Pro-Inflammatory Myocardial Environment at Early Stages of Diabetes: Protective Role of Resveratrol

Background: Little information is currently available concerning the relative contribution of cardiac parenchymal and stromal cells in the activation of the pro-inflammatory signal cascade, at the initial stages of diabetes. Similarly, the effects of early resveratrol (RSV) treatment on the negative impact of diabetes on the different myocardial cell compartments remain to be defined. Methods: In vitro challenge of neonatal cardiomyocytes and fibroblasts to high glucose and in vivo/ex vivo experiments on a rat model of Streptozotocin-induced diabetes were used to specifically address these issues. Results: In vitro data indicated that, besides cardiomyocytes, neonatal fibroblasts contribute to generating initial changes in the myocardial environment, in terms of pro-inflammatory cytokine expression. These findings were mostly confirmed at the myocardial tissue level in diabetic rats, after three weeks of hyperglycemia. Specifically, monocyte chemoattractant protein-1 and Fractalkine were up-regulated and initial abnormalities in cardiomyocyte contractility occurred. At later stages of diabetes, a selective enhancement of pro-inflammatory macrophage M1 phenotype and a parallel reduction of anti-inflammatory macrophage M2 phenotype were associated with a marked disorganization of cardiomyocyte ultrastructural properties. RSV treatment inhibited pro-inflammatory cytokine production, leading to a recovery of cardiomyocyte contractile efficiency and a reduced inflammatory cell recruitment. Conclusion: Early RSV administration could inhibit the pro-inflammatory diabetic milieu sustained by different cardiac cell types.

Cardiac antibody production to self-antigens in children and adolescents during and following the correction of severe diabetic ketoacidosis

Diabetic cardiomyopathy (DC) is an independent phenotype of diabetic cardiovascular disease. The understanding of the pathogenesis of DC in young patients with type 1 diabetes (T1D) is limited. The cardiac insults of diabetic ketoacidosis (DKA) and progression of DC could include development of antibodies (Abs) to cardiac self-antigens (SAgs) such as: myosin (M), vimentin (V) and k-alpha 1 tubulin (Kα1T). The goal of this study is to determine if the insults of severe DKA and its inflammatory cascade are associated with immune responses to SAgs. Development of Abs to the SAgs were determined by an ELISA using sera collected at three time points in relation to severe DKA (pH < 7.2). Results demonstrate significant differences between the development of Abs to VIM and a previously reported diastolic abnormality (DA) during DKA and its treatment and a NDA group at 2-3 months post DKA (p = 0.0452). A significant association is present between T1D duration (<3 years) and Abs to Kα1T (p = 0.0134). Further, Abs to MYO and VIM are associated with inflammatory cytokines. We propose that severe DKA initiates the synthesis of Abs to cardiac SAgs that are involved in the early immunopathogenesis of DC in young patients with T1D.

Anti-Diabetic Effects of Madecassic Acid and Rotundic Acid

Anti-diabetic effects of madecassic acid (MEA) and rotundic acid (RA) were examined. MEA or RA at 0.05% or 0.1% was supplied to diabetic mice for six weeks. The intake of MEA, not RA, dose-dependently lowered plasma glucose level and increased plasma insulin level. MEA, not RA, intake dose-dependently reduced plasminogen activator inhibitor-1 activity and fibrinogen level; as well as restored antithrombin-III and protein C activities in plasma of diabetic mice. MEA or RA intake decreased triglyceride and cholesterol levels in plasma and liver. Histological data agreed that MEA or RA intake lowered hepatic lipid droplets, determined by ORO stain. MEA intake dose-dependently declined reactive oxygen species (ROS) and oxidized glutathione levels, increased glutathione content and maintained the activity of glutathione reductase and catalase in the heart and kidneys of diabetic mice. MEA intake dose-dependently reduced interleukin (IL)-1β, IL-6, tumor necrosis factor-α and monocyte chemoattractant protein-1 levels in the heart and kidneys of diabetic mice. RA intake at 0.1% declined cardiac and renal levels of these inflammatory factors. These data indicated that MEA improved glycemic control and hemostatic imbalance, lowered lipid accumulation, and attenuated oxidative and inflammatory stress in diabetic mice. Thus, madecassic acid could be considered as an anti-diabetic agent.

Bifidobacterium species lower serum glucose, increase expressions of insulin signaling proteins, and improve adipokine profile in diabetic mice

This study, using C57BL/6J mice with streptozotocin (STZ)-induced diabetes, aimed to determine whether Bifidobacterium species (spp.) both induces the expressions of proteins in the insulin signaling pathway and enhances the expressions of certain adipocytokines. The protein expressions of IκB kinase alpha (IKKα), IκB kinase beta (IKKβ), nuclear factor-kappaB inhibitor alpha (IκBα), and the mitogen-activated protein kinase (MAPK) pathway were also investigated. Oral administration of Bifidobacterium spp. reduced blood glucose levels significantly and increased the protein expressions of insulin receptor beta, insulin receptor substrate 1, protein kinase B (Akt/PKB), IKKα, and IκBα. Extracellular-signal-regulated kinase 2 (ERK2) showed increased expression. Bifidobacterium spp. also induced the adiponectin expression and decreased both macrophage chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) expression. In addition, IKKβ, c-Jun NH2-terminal kinase (JNK) and p38 MAP kinase expressions showed no significant changes in both groups. In conclusion, Bifidobacterium spp. may be the promising bacteria for treating diabetes.

A New Insight Into Sudden Cardiac Death in Young People: A Systematic Review of Cases of Takotsubo Cardiomyopathy

Takotsubo cardiomyopathy (TTC) causes sudden cardiac death and has garnered increased attention worldwide in recent years. However, few studies have clearly classified the risk factors for this disease, including gender, race and morbidity, as well as the physical and mental stressors that can exacerbate the disease, particularly in young patients. To better analyze the characteristics of young TTC patients, we performed a systematic review of reported cases involving young patients.A computer-assisted search was performed using prominent electronic medical information sources to identify literature published between January 1965 and December 2013. Relevant studies containing clinical data of young TTC patients were included.Ninety-six records that included information about 104 cases were ultimately selected for our review. Several of the following results were noted: First, physical stress was more likely to exacerbate TTC than was mental stress in young patients. Second, more female than male TTC patients were noted among both young patients and the general population. Third, ethnicity appears to play no role in the disease, as no significant differences were noted among individuals of different races with respect to clinical characteristics, morbidity or stressors. Fourth, the clinical manifestations of TTC were similar to those of other cardiac diseases, including coronary heart disease. However, TTC may be detected using the combination of echocardiography and ventriculography.Clinicians should consider TTC if young patients present with symptoms similar to those of coronary heart disease so that harmful treatments such as coronary artery stent placement may be avoided. Moreover, the answers to questions regarding the clinical diagnostic criteria, etiology, pathophysiology, and the management of this syndrome in youth remain unclear; therefore, further research is needed.

MCP-1-induced protein attenuates post-infarct cardiac remodeling and dysfunction through mitigating NF-κB activation and suppressing inflammation-associated microRNA expression

MCP-1-induced protein (MCPIP, also known as ZC3H12A) has recently been uncovered to act as a negative regulator of inflammation. Expression of MCPIP was elevated in the ventricular myocardium of patients with ischemic heart failure. However, the role of MCPIP in the development of post-infarct cardiac inflammation and remodeling is unknown. The objective of the present study was to investigate whether MCPIP exerts an inhibitory effect on the cardiac inflammatory response and adverse remodeling after myocardial infarction (MI). Mice with cardiomyocyte-specific expression of MCPIP and their wild-type littermates (FVB/N) were subjected to permanent ligation of left coronary artery. The levels of MCPIP were significantly increased in the ischemic myocardium and sustained for 4 weeks after MI. Acute infarct size was comparable between groups. However, constitutive overexpression of MCPIP in the murine heart resulted in improved survival rate, decreased cardiac hypertrophy, less of fibrosis and scar formation, and better cardiac performance at 28 days after MI, along with a markedly reduced monocytic cell infiltration, less cytokine expression, decreased caspase-3/7 activities and apoptotic cell death compared to the wild-type hearts. Cardiomyocyte-specific expression of MCPIP also attenuated activation of cardiac NF-κB signaling and expression of inflammation-associated microRNAs (miR-126, -146a, -155, and -199a) when compared with the post-infarct wild-type hearts. In vitro, MCPIP expression suppressed hypoxia-induced NF-κB-luciferase activity in cardiomyocytes. In conclusion, MCPIP expression in the ischemic myocardium protects against adverse cardiac remodeling and dysfunction following MI by modulation of local myocardial inflammation, possibly through mitigating NF-κB signaling and suppressing inflammation-associated microRNA expression.