scholarly journals Diastolic dysfunction in a pre-clinical model of diabetes is associated with changes in the cardiac non-myocyte cellular composition

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Charles D. Cohen ◽  
Miles J. De Blasio ◽  
Man K. S. Lee ◽  
Gabriella E. Farrugia ◽  
Darnel Prakoso ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Diastolic Dysfunction ◽  
Systolic Function ◽  
Cardiac Fibroblasts ◽  
Detailed Examination ◽  
Diabetic Mice ◽  
Cellular Mechanisms ◽  
Clinical Model ◽  
Cardiac Ventricles

Abstract Background Diabetes is associated with a significantly elevated risk of cardiovascular disease and its specific pathophysiology remains unclear. Recent studies have changed our understanding of cardiac cellularity, with cellular changes accompanying diabetes yet to be examined in detail. This study aims to characterise the changes in the cardiac cellular landscape in murine diabetes to identify potential cellular protagonists in the diabetic heart. Methods Diabetes was induced in male FVB/N mice by low-dose streptozotocin and a high-fat diet for 26-weeks. Cardiac function was measured by echocardiography at endpoint. Flow cytometry was performed on cardiac ventricles as well as blood, spleen, and bone-marrow at endpoint from non-diabetic and diabetic mice. To validate flow cytometry results, immunofluorescence staining was conducted on left-ventricles of age-matched mice. Results Mice with diabetes exhibited hyperglycaemia and impaired glucose tolerance at endpoint. Echocardiography revealed reduced E:A and e’:a’ ratios in diabetic mice indicating diastolic dysfunction. Systolic function was not different between the experimental groups. Detailed examination of cardiac cellularity found resident mesenchymal cells (RMCs) were elevated as a result of diabetes, due to a marked increase in cardiac fibroblasts, while smooth muscle cells were reduced in proportion. Moreover, we found increased levels of Ly6Chi monocytes in both the heart and in the blood. Consistent with this, the proportion of bone-marrow haematopoietic stem cells were increased in diabetic mice. Conclusions Murine diabetes results in distinct changes in cardiac cellularity. These changes—in particular increased levels of fibroblasts—offer a framework for understanding how cardiac cellularity changes in diabetes. The results also point to new cellular mechanisms in this context, which may further aid in development of pharmacotherapies to allay the progression of cardiomyopathy associated with diabetes.

Diastolic Dysfunction in a Pre-clinical Model of Diabetes Is Associated With Changes in the Cardiac Non-myocyte Cellular Composition

2021 ◽  
Author(s):  
Charles D. Cohen ◽  
Miles J. De Blasio ◽  
Man K. S. Lee ◽  
Gabriella E. Farrugia ◽  
Darnel Prakoso ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Diastolic Dysfunction ◽  
Systolic Function ◽  
Cardiac Fibroblasts ◽  
Detailed Examination ◽  
Diabetic Mice ◽  
Cellular Mechanisms ◽  
Clinical Model ◽  
Cardiac Ventricles

Abstract Background:Diabetes is associated with a significantly elevated risk of cardiovascular disease and its specific pathophysiology remains unclear. Recent studies have changed our understanding of cardiac cellularity, with cellular changes accompanying diabetes yet to be examined in detail. This study aims to characterise the changes in the cardiac cellular landscape in murine diabetes to identify potential cellular protagonists in the diabetic heart.Methods:Diabetes was induced in male FVB/N mice by low-dose streptozotocin and a high-fat diet for 26-weeks. Cardiac function was measured by echocardiography at endpoint. Flow cytometry was performed on cardiac ventricles as well as blood, spleen, liver, and bone-marrow at endpoint from non-diabetic and diabetic mice. To validate flow cytometry results, immunofluorescence staining was conducted on left-ventricles of age-matched mice.ResultsMice with diabetes exhibited hyperglycaemia and impaired glucose tolerance at endpoint. Echocardiography revealed reduced E:A and e’:a’ ratios in diabetic mice indicating diastolic dysfunction. Systolic function was not different between the experimental groups. Detailed examination of cardiac cellularity found resident mesenchymal cells (RMCs) were elevated as a result of diabetes, due to a marked increase in cardiac fibroblasts, while smooth muscle cells were reduced in proportion. Moreover, we found increased levels of Ly6Chi monocytes in both the heart and in the blood. Consistent with this, the proportion of bone-marrow haematopoietic stem cells were increased in diabetic mice.Conclusions:Murine diabetes results in distinct changes in cardiac cellularity. These changes—in particular increased levels of fibroblasts—offer a framework for understanding how cardiac cellularity changes in diabetes. The results also point to new cellular mechanisms in this context, which may further aid in development of pharmacotherapies to allay the progression of cardiomyopathy associated with diabetes.

scholarly journals Rap1a Overlaps the AGE/RAGE Signaling Cascade to Alter Expression of α-SMA, p-NF-κB, and p-PKC-ζ in Cardiac Fibroblasts Isolated from Type 2 Diabetic Mice

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 557
Author(s):  
Stephanie D. Burr ◽  
James A. Stewart
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Hydrogen Peroxide ◽  
Cardiac Fibroblasts ◽  
The Body ◽  
Signaling Cascade ◽  
Diabetic Mice ◽  
Pkc Ζ ◽  
Type 2 Diabetic

Cardiovascular disease, specifically heart failure, is a common complication for individuals with type 2 diabetes mellitus. Heart failure can arise with stiffening of the left ventricle, which can be caused by “active” cardiac fibroblasts (i.e., myofibroblasts) remodeling the extracellular matrix (ECM). Differentiation of fibroblasts to myofibroblasts has been demonstrated to be an outcome of AGE/RAGE signaling. Hyperglycemia causes advanced glycated end products (AGEs) to accumulate within the body, and this process is greatly accelerated under chronic diabetic conditions. AGEs can bind and activate their receptor (RAGE) to trigger multiple downstream outcomes, such as altering ECM remodeling, inflammation, and oxidative stress. Previously, our lab has identified a small GTPase, Rap1a, that possibly overlaps the AGE/RAGE signaling cascade to affect the downstream outcomes. Rap1a acts as a molecular switch connecting extracellular signals to intracellular responses. Therefore, we hypothesized that Rap1a crosses the AGE/RAGE cascade to alter the expression of AGE/RAGE associated signaling proteins in cardiac fibroblasts in type 2 diabetic mice. To delineate this cascade, we used genetically different cardiac fibroblasts from non-diabetic, diabetic, non-diabetic RAGE knockout, diabetic RAGE knockout, and Rap1a knockout mice and treated them with pharmacological modifiers (exogenous AGEs, EPAC, Rap1a siRNA, and pseudosubstrate PKC-ζ). We examined changes in expression of proteins implicated as markers for myofibroblasts (α-SMA) and inflammation/oxidative stress (NF-κB and SOD-1). In addition, oxidative stress was also assessed by measuring hydrogen peroxide concentration. Our results indicated that Rap1a connects to the AGE/RAGE cascade to promote and maintain α-SMA expression in cardiac fibroblasts. Moreover, Rap1a, in conjunction with activation of the AGE/RAGE cascade, increased NF-κB expression as well as hydrogen peroxide concentration, indicating a possible oxidative stress response. Additionally, knocking down Rap1a expression resulted in an increase in SOD-1 expression suggesting that Rap1a can affect oxidative stress markers independently of the AGE/RAGE signaling cascade. These results demonstrated that Rap1a contributes to the myofibroblast population within the heart via AGE/RAGE signaling as well as promotes possible oxidative stress. This study offers a new potential therapeutic target that could possibly reduce the risk for developing diabetic cardiovascular complications attributed to AGE/RAGE signaling.

scholarly journals DPP-4 inhibitor induces FGF21 expression via sirtuin 1 signaling and improves myocardial energy metabolism

2020 ◽  
Vol 36 (1) ◽  
pp. 136-146
Author(s):  
Nozomi Furukawa ◽  
Norimichi Koitabashi ◽  
Hiroki Matsui ◽  
Hiroaki Sunaga ◽  
Yogi Umbarawan ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Systolic Function ◽  
Cardiac Fibroblasts ◽  
Left Ventricular ◽  
Sirtuin 1 ◽  
Fibroblast Growth Factor 21 ◽  
Mouse Heart ◽  
Acid Uptake ◽  
Dipeptidyl Peptidase 4 ◽  
Fgf21 Expression

AbstractDipeptidyl peptidase-4 (DPP-4) inhibitors are widely used incretin-based therapy for the treatment of type 2 diabetes. We investigated the cardioprotective effect of a DPP-4 inhibitor, vildagliptin (vilda), on myocardial metabolism and cardiac performance under pressure overload. Mice were treated with either vehicle or vilda, followed by transverse aortic constriction (TAC). After 3 weeks of TAC, cardiac hypertrophy and impairment of systolic function were attenuated in vilda-treated mice. Pressure–volume analysis showed that vilda treatment significantly improved left-ventricular contractile efficiency in TAC heart. Myocardial energy substrate analysis showed that vilda treatment significantly increased glucose uptake as well as fatty acid uptake. Fibroblast growth factor 21 (FGF21), a peptide involved in the regulation of energy metabolism, increased in TAC heart and was further increased by vilda treatment. FGF21 was strongly expressed in cardiac fibroblasts than in cardiomyocytes in mouse heart after TAC with vilda treatment. Vilda treatment markedly induced FGF21 expression in human cardiac fibroblasts through a sirtuin (Sirt) 1-mediated pathway, suggesting that fibroblast-mediated FGF21 expression may regulate energy metabolism and exert vilda-mediated beneficial effects in stressed heart. Vilda induced a metabolic regulator, FGF21 expression in cardiac fibroblasts via Sirt1, and increased contractile efficiency in murine pressure-overloaded heart.

Immature platelet values indicate impaired megakaryopoietic activity in neonatal early-onset thrombocytopenia

2010 ◽  
Vol 103 (05) ◽  
pp. 1016-1021 ◽  
Author(s):  
Hannes Hammer ◽  
Christoph Bührer ◽  
Christof Dame ◽  
Malte Cremer ◽  
Andreas Weimann
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Intensive Care ◽  
Early Onset ◽  
Absolute Number ◽  
Severe Thrombocytopenia ◽  
Platelet Counts ◽  
Immature Platelet Fraction ◽  
Neonatal Thrombocytopenia ◽  
Immature Platelets

SummaryNewly released platelets, referred to as immature platelets, can be reliably quantified based on their RNA content by flow cytometry in an automated blood analyser. The absolute number of immature platelets (IPF#) and the immature platelet fraction (IPF%) reflect megakaryopoietic activity. We aimed to analyse the implication of these parameters in analysing the pathomechanism of early-onset neonatal thrombocytopenia. Platelet counts and IPF were determined at day 1 to 3 (d1 to d3) in 857 neonates admitted to intensive care. In thrombocytopenic patients (platelet counts<150 x 109/l, n=129), IPF# was significantly lower (8.5 ± 2.7 x 109/l), than in non-thrombocytopenic neonates (9.5 ± 3.6 x 109/l, n=682, p<0.05). IPF% was significantly higher in thrombocytopenic (9.3 ± 7.9%) vs. non-thrombocytopenic neonates (4.1 ± 1.8%, p<0.001). While neonates with early-onset infection (n=134) had lower platelet counts (199 ± 75 x 109/l) compared to controls (230 ± 68 x 109/l, n=574, p<0.01), there were no differences in IPF# or IPF%. Likewise, “small for gestational age” infants (SGA, n=149) had lower platelet counts at d1 (199 ± 75 x 109/l, p<0.001) than controls, but no differences in IPF. A trend towards lower IPF# was detected if SGA infants with platelet counts <100 x 109/l (5.4 ± 3.9 x 109/l, n=11) and thrombocytopenic neonates with infection (9.9 ± 7.3 x 109/l, n=10, p=0.11) were compared. The evaluation of IPF# indicates that thrombocytopenia in neonates is likely due to a combination of increased platelet consumption and inadequate megakaryopoietic response by the neonatal bone marrow. Furthermore, SGA neonates with moderate and severe thrombocytopenia might have a pronounced suppression of megakaryopoiesis compared to neonates with infection.

Long-term levosimendan treatment improves systolic function and myocardial relaxation in mice with cardiomyocyte-specific disruption of the Serca2 gene

2013 ◽  
Vol 115 (10) ◽  
pp. 1572-1580 ◽  
Author(s):  
Vigdis Hillestad ◽  
Frank Kramer ◽  
Stefan Golz ◽  
Andreas Knorr ◽  
Kristin B. Andersson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heart Failure ◽  
Cardiac Function ◽  
Diastolic Dysfunction ◽  
Systolic Function ◽  
Cytosolic Calcium ◽  
Left Ventricular ◽  
Pressure Measurements ◽  
Human Heart Failure

In human heart failure (HF), reduced cardiac function has, at least partly, been ascribed to altered calcium homeostasis in cardiomyocytes. The effects of the calcium sensitizer levosimendan on diastolic dysfunction caused by reduced removal of calcium from cytosol in early diastole are not well known. In this study, we investigated the effect of long-term levosimendan treatment in a murine model of HF where the sarco(endo)plasmatic reticulum ATPase ( Serca) gene is specifically disrupted in the cardiomyocytes, leading to reduced removal of cytosolic calcium. After induction of Serca2 gene disruption, these mice develop marked diastolic dysfunction as well as impaired contractility. SERCA2 knockout (SERCA2KO) mice were treated with levosimendan or vehicle from the time of KO induction. At the 7-wk end point, cardiac function was assessed by echocardiography and pressure measurements. Vehicle-treated SERCA2KO mice showed significantly diminished left-ventricular (LV) contractility, as shown by decreased ejection fraction, stroke volume, and cardiac output. LV pressure measurements revealed a marked increase in the time constant (τ) of isovolumetric pressure decay, showing impaired relaxation. Levosimendan treatment significantly improved all three systolic parameters. Moreover, a significant reduction in τ toward normalization indicated improved relaxation. Gene-expression analysis, however, revealed an increase in genes related to production of the ECM in animals treated with levosimendan. In conclusion, long-term levosimendan treatment improves both contractility and relaxation in a heart-failure model with marked diastolic dysfunction due to reduced calcium transients. However, altered gene expression related to fibrosis was observed.

Abstract 12622: Western Diet for One Month Impairs Myocardial Energetics and Both Systolic and Diastolic Pump Function in the Mouse Heart

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ivan Luptak ◽  
Aaron L Sverdlov ◽  
Aly Elezaby ◽  
Edward J Miller ◽  
David R Pimentel ◽  
...  
Keyword(s):  
Diastolic Dysfunction ◽  
Mitochondrial Dysfunction ◽  
Systolic Function ◽  
Atp Synthesis ◽  
Contractile Reserve ◽  
31P Nmr Spectroscopy ◽  
Pump Function ◽  
High Workload ◽  
Myocardial Energetics ◽  
Intact Heart

Background and Significance: Metabolic heart disease(MHD) is common in patients with obesity, type 2 diabetes and/or metabolic syndrome. We found cardiac mitochondrial dysfunction in mice with obesity-related MHD due to consumption of a high fat high sucrose (HFHS) diet. The effects of diet-induced obesity on cardiac energetics and pump function in the intact organ are largely unknown. Hypothesis: We tested the hypothesis that cardiac mitochondrial dysfunction due to HFHS diet for one month impairs energetic and contractile reserve in the intact heart. Methods and Results: Mice were fed a HFHS or control diet (CD) for 1 month. In isolated cardiac mitochondria from HFHS-fed mice (vs. CD) the maximal rate of ATP synthesis was decreased for complex I (down by 42%; p<0.05) and II (down by 37%; p<0.05) substrates. We measured myocardial energetics in isolated perfused hearts using 31P NMR spectroscopy at baseline (450 bpm, 2 mM Ca++) and high workload (600 bpm, 4 mM Ca++) in HFHS (n=7) and CD (n=8) hearts. In HFHS-fed hearts, myocardial ATP concentration was the same at baseline (10.5±0.4 vs 10.4±0.5 mM) and high workload (7.4±0.9 vs. 7.5±0.5 mM) as that of CD hearts. However, in HFHS-fed hearts the concentration of phosphocreatine, which reflects energy reserve, was decreased at baseline (13±0.7 vs. 17.5±0.8 mM; p<0.01) and decreased further at high workload (down to 7.3±0.7; p<0.01 vs. baseline and p<0.01 vs. CD at 10.5±0.4 mM) - indicating a mismatch between ATP production and utilization. In HFHS hearts, the diastolic pressure-volume relationship was shifted upward and leftward at baseline, indicative of diastolic dysfunction. In HFHS hearts, baseline systolic function was preserved (rate pressure product 41,600±2,200 vs. 41,000±2,000 mmHg/min), but was decreased at high workload (54,800±7,200 vs. 85,300±4,300 mmHg/min; p<0.01 vs. CD), reflecting an impaired contractile reserve. Conclusion: Consumption of a HFHS diet for one month causes cardiac mitochondrial dysfunction with reduced ATP synthesis leading to impaired energetic reserve in the intact heart. Diastolic dysfunction at rest and the impaired ability to increase systolic function with increased work demands may result from impaired energetics in MHD.

Abstract T P238: Microglial CX3CR1 Required for M2 Polarization and Recovery After Intracerebral Hemorrhage

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Roslyn A Taylor ◽  
Matthew D Hammond ◽  
Youxi Ai ◽  
Lauren H Sansing
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Intracerebral Hemorrhage ◽  
Gait Analysis ◽  
Functional Outcome ◽  
Cylinder Test ◽  
M2 Microglia ◽  
Inflammatory Phenotype ◽  
Peripheral Leukocytes ◽  
The Right

Introduction: Intracerebral hemorrhage (ICH) results in the activation of microglia, the resident immune cells of the central nervous system. Microglia may polarize into an M1, pro-inflammatory phenotype, or an M2 phenotype associated with repair. CX3CR1 is a chemokine receptor on microglia and monocyte subsets. CX3CR1-null microglia have been shown to have dysregulated inflammation. We hypothesize that CX3CR1-null microglia have a prolonged M1 phenotype, contributing to worse functional outcome after ICH. Methods: ICH was modeled by injection of 20μl of blood into the right striatum. Neurological deficit was quantified using digital gait analysis, cylinder test, and beam walking. Mice were sacrificed 14 days after ICH; brains were harvested for flow cytometry and immunohistochemistry (IHC). C57BL/6 (WT) and CX3CR1 GFP/GFP (CX3CR1-null) mice were irradiated and reconstituted with bone marrow from WT mice carrying the congenic marker CD45.1 to generate bone marrow chimeras (CD45.1WT or CD45.1CX3CR1-null). M1 microglia were identified as expressing MHCII and M2 microglia with CD206. Results: The CD45.1CX3CR1-null mice show worse functional outcome 14 days after ICH by cylinder test (p=0.002), beam walking (p=<0.001) and gait analysis (p=0.02). By flow cytometry, few peripheral leukocytes remain in the brain at 14 days, indicating that F4/80 + and CD11b + cells visualized by IHC are likely microglia, not peripheral macrophages. By IHC, CD45.1 CX3CR1-null mice have significantly more amoeboid F4/80 + MHCII + cells per field (M1 microglia) than CD45.1WT mice (p=0.02). CD45.1 CX3CR1-null mice have significantly fewer CD11b + CD206 + cells per field (M2 microglia) compared to CD45.1WT mice (p=0.04). Conclusions: Our results suggest microglial CX3CR1 signaling is necessary for microglia to transition from M1 to M2 and contribute to recovery after ICH.

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