Increased vascular permeability after cardiopulmonary bypass in patients with diabetes is associated with increased expression of vascular endothelial growth factor and hepatocyte growth factor

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

Decreased expression of ErbB2 on left ventricular epicardial cells in patients with diabetes mellitus

We investigated the cell surface expression of ErbB receptors on left ventricular (LV) epicardial endothelial cells and CD105⁺ cells obtained from cardiac biopsies of patients undergoing coronary artery bypass grafting surgery (CABG). Endothelial cells and CD105⁺ non-endothelial cells were freshly isolated from LV epicardial biopsies obtained from 15 subjects with diabetes mellitus (DM) and 8 controls. The expression of ErbB receptors was examined using flow cytometry. We found that diabetes mellitus (DM) and high levels of hemoglobin A1C are associated with reduced expression of ErbB2. To determine if the expression of ErbB2 receptors is regulated by glucose levels, we examined the effect of high Glucose in human microvascular endothelial cells (HMEC-1) and CD105⁺ non-endothelial cells, using a novel flow cytometric approach to simultaneously determine the total level, cell surface expression, and phosphorylation of ErbB2. Incubation of cells in the presence of 25 mM d-glucose resulted in decreased cell surface but not total levels of ErbB2. The level of ErbB2 at the cell surface is controlled by disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) that is expressed on LV epicardial cells. Inhibition of ADAM10 prevented the high glucose-dependent decrease in the cell surface expression of ErbB2. We suggest that high Glucose depresses ErbB receptor signaling in endothelial cells and cardiac progenitor cells via the promotion of ADAM10-dependent cleavage of ErbB2 at the cell surface, thus contributing to vascular dysfunction and adverse remodeling seen in diabetic patients.

Narrative review of the systemic inflammatory reaction to cardiac surgery and cardiopulmonary bypass

Background

Data from large cardiac surgery registries have been depicting a downward trend of mortality and morbidities in the last 20 years. However, despite decades of medical evolution, cardiac surgery and cardiopulmonary bypass still provoke a systemic inflammatory response, which occasionally leads to worsened outcome. This article seeks to outline the mechanism of the phenomenon.

Methods

A thorough review of the literature has been performed. Criteria for considering studies for this non‐systematic review were as follows: observational and interventional studies investigating the systemic inflammatory response to cardiac surgery, experimental studies describing relevant molecular mechanisms, and essential review studies pertinent to the topic.

Results

The intrinsic variability of the inflammatory response to cardiac surgery, together with its heterogenous perception among clinicians, as well as the arduousness to early discriminate high‐responder patients from those who will not develop a clinically relevant reaction, concurred to hitherto unconclusive randomized controlled trials. Furthermore, peremptory knowledge about the pathophysiology of maladaptive inflammation following heart surgery is still lacking.

Conclusions

Systemic inflammation following cardiac surgery is a frequent entity that occasionally becomes clinically relevant. Specific genomic differences, age, and other preoperative factors influence the magnitude of the response, which elements display extreme redundancy and pleiotropism that the target of a single pathway cannot represent a silver bullet.

Chronic Inhibition of mROS Protects Against Coronary Endothelial Dysfunction in Mice With Diabetes

Diabetes is associated with coronary endothelial dysfunction. Persistent oxidative stress during diabetes contributes to coronary endothelial dysfunction. The mitochondria are main sources of reactive oxygen species (ROS) in diabetes, and mitochondria-targeted antioxidant mito-Tempo can prevent mitochondrial reactive oxygen species (mROS) generation in a variety of disorders. Inhibition/inactivation of small-conductance Ca²⁺-activated K⁺ (SK) channels contribute to diabetic downregulation of coronary endothelial function/relaxation. However, few investigated the role of mROS on endothelial dysfunction/vasodilation and endothelial SK channel downregulation in diabetes. The aim of present study was to investigate the chronic administration of mito-Tempo, on coronary vasodilation, and endothelial SK channel activity of mice with or without diabetes. Mito-Tempo (1 mg/kg/day) was applied to the mice with or without diabetes (n = 10/group) for 4 weeks. In vitro relaxation response of pre-contracted arteries was examined in the presence or absence of the vasodilatory agents. SK channel currents of the isolated mouse heart endothelial cells were measured using whole-cell patch clamp methods. At baseline, coronary endothelium-dependent relaxation responses to ADP and the selective SK channel activator NS309 and endothelial SK channel currents were decreased in diabetic mice compared with that in non-diabetic (ND) mice (p < 0.05). After a 4-week treatment with mito-Tempo, coronary endothelium-dependent relaxation response to ADP or NS309 and endothelial SK channel currents in the diabetic mice was significantly improved when compared with that in untreated diabetic mice (p < 0.05). Interestingly, coronary relaxation responses to ADP and NS309 and endothelial SK channel currents were not significantly changed in ND mice after mito-Tempo treatment, as compared to that of untreated control group. Chronic inhibition of endothelial mROS appears to improve coronary endothelial function/dilation and SK channel activity in diabetes, and mROS inhibitors may be a novel strategy to treat vascular complications in diabetes.

Hypoxia inducible factor-1α/vascular endothelial growth factor signaling activation correlates with response to radiotherapy and its inhibition reduces hypoxia-induced angiogenesis in lung cancer

Like other tumors, lung cancer must induce angiogenesis as it grows. Hypoxia-inducible factor 1α (HIF-1α) is the inducible subunit of the HIF-1 transcription factor that regulates genes involved in the response to hypoxia, some of which contributes to angiogenesis. Vascular endothelial growth factor (VEGF) is one of the genes upregulated by HIF-1 and is the primary cytokine in relation to angiogenesis. In this study we tested whether aberrant activation of hypoxia inducible factor-1α/vascular endothelial growth factor (HIF-1α/VEGF) pathway correlates with response to radiotherapy and examined the response of lung cancer cells to hypoxia in vitro. We determined increased expressions of HIF-1α and VEGF-A in 76 cancerous tissues of responders (complete remission and partial remission). HIF-1α and VEGF-A were shown to be upregulated in lung cancer cells in response to hypoxia. The treatment with anti-HIF-1α siRNA prior to hypoxia exposure was shown to decrease HIF-1α and VEGF-A expressions and reduce hypoxia-induced angiogenesis, suggesting that HIF-1α expression resulted in increased VEGF-A expression and activation of HIF-1α/VEGF pathway was responsible for hypoxia-induced angiogenesis. In conclusion, we identified the relationship between HIF-1α/VEGF pathway and response to radiotherapy and its role in angiogenesis in lung cancer in vitro. HIF-1α/VEGF pathway as a target for antiangiogenic treatment strategies for this tumor requires further investigation.

Microvascular dysfunction in patients with diabetes after cardioplegic arrest and cardiopulmonary bypass

PURPOSE OF REVIEW

The purpose of the current review is to describe the changes of microvascular function in patients with diabetes after cardioplegic arrest and cardiopulmonary bypass (CPB) and cardiac surgery.

RECENT FINDINGS

Cardiac surgery, especially that involving cardioplegia and CPB, is associated with significant changes in vascular reactivity of coronary/peripheral microcirculation, vascular permeability, gene/protein expression, and programmed cell death, as well as with increased morbidity and mortality after surgical procedures. In particular, these changes are more profound in patients with poorly controlled diabetes.

SUMMARY

Because alterations in vasomotor regulation are critical aspects of mortality and morbidity of cardioplegia/CPB, a better understanding of diabetic regulation of microvascular function may lead to improved postoperative outcomes of patients with diabetes after cardioplegia/CPB and cardiac surgery.

Diabetes Upregulation of Cyclooxygenase 2 Contributes to Altered Coronary Reactivity After Cardiac Surgery

BACKGROUND

We hypothesized that upregulation of inducible cyclooxygenase 2 (COX-2) contributes to altered coronary arteriolar reactivity early after cardioplegic arrest and cardiopulmonary bypass (CP/CPB) in patients with diabetes mellitus who are undergoing cardiac surgery.

METHODS

The right atrial tissue samples of nondiabetes (ND), controlled diabetes (CDM), and uncontrolled diabetes (UDM) patients undergoing cardiac surgery were harvested before and after CP/CPB. Coronary arterioles (80 to 150 μm) were dissected from the harvested atrial tissue samples, cannulated, and pressurized. The changes in diameter were measured with video microscopy. The protein expression and localization of COX-1 and COX-2 were assayed by Western blot and immunohistochemistry.

RESULTS

In the diabetes arterioles, bradykinin-induced relaxation response was inhibited by the selective COX-2 inhibitor NS398 at baseline (p < 0.05). This effect was more pronounced in UDM arterioles than CDM (p < 0.05). After CP/CPB, bradykinin-induced responses in all groups were inhibited by NS398, but this effect was more pronounced in the UDM patients (p < 0.05). The intensities of COX-2 staining of coronary arterioles and COX-2 protein levels in myocardium were higher in diabetes than nondiabetes at baseline (p < 0.05). The post-CP/CPB protein levels of the inducible COX-2 were significantly increased compared with pre-CP/CPB values in all groups (p < 0.05), whereas this increase was higher with diabetes than with ND (p < 0.05). Furthermore, these effects were more profound in UDM than CDM (p < 0.05).

CONCLUSIONS

Diabetes and CP/CPB are associated with upregulation in COX-2 expression in human coronary vasculature. Upregulation of COX-2 expression may contribute to bradykinin-induced coronary arteriolar relaxation in diabetic patients undergoing cardiac surgery.

Cyclooxygenase 2 contributes to bradykinin-induced microvascular responses in peripheral arterioles after cardiopulmonary bypass

BACKGROUND

Diabetic patients are associated with impaired peripheral microvascular function after cardiopulmonary bypass (CPB) and cardiac surgery. We hypothesized that upregulation of the inducible cyclooxygenase 2 (COX-2) contributes to altered microvascular reactivity of peripheral arterioles in diabetic patients undergoing CPB and cardiac surgery.

METHODS

Skeletal muscle samples of nondiabetic (ND) patients and patients with diabetes mellitus (DM; n = 8 per group) undergoing cardiac surgery were harvested before and after CPB. The protein expression/localization of COX-2 was assayed by Western blotting and immunohistochemistry. Peripheral arterioles were dissected from the harvested skeletal muscle tissue samples, the isolated arterioles (80-180 μm) were cannulated and pressurized, and changes in diameter were measured with video microscopy. In-vitro relaxation responses of precontracted arterioles were examined in the presence of the endothelium-dependent vasodilator bradykinin (10^-10 to 10^-6M) and in the presence or absence of the selective COX-2 inhibitor NS398 (10^-5M).

RESULTS

The post-CPB protein levels of the inducible COX-2 were significantly increased compared with pre-CPB values in both the ND and DM groups (P < 0.05), whereas, this increase was higher in DM than that of ND (P < 0.05). In the DM arterioles, not the ND vessels, bradykinin-induced relaxation response was inhibited in the presence of the specific COX-2 inhibitor NS398 at baseline (P < 0.05). After CPB, bradykinin-induced relaxation response of the ND and DM arterioles was inhibited in the presence of the specific COX-2 inhibitor NS398, but this effect was more pronounced in the diabetic patients (P < 0.05).

CONCLUSIONS

Diabetes and CPB are associated with upregulation in COX-2 expression/activation in human peripheral microvasculature. This alteration may lead to altered peripheral microvascular reactivity in diabetic patients undergoing cardiac surgery.

Diabetes and Cardioplegia

Cardiac surgery with cardiopulmonary bypass and cardioplegic arrest is associated with injury to the vasculature and microcirculation leading to coronary microvascular dysfunction, permeability changes and cardiac dysfunction. In the setting of cardiopulmonary bypass with cardioplegia, poorly-controlled diabetes is associated with significant changes in endothelium-dependent and independent vascular dysfunction, vascular reactivity, vascular permeability, protein expression, cell death, coronary/peripheral microcirculation and reduced vasomotor tone leading to hypotension and impaired endothelial function. The gene expression profiles after cardiopulmonary bypass with cardioplegic arrest is quantitatively and qualitatively different in patients with diabetes. Gene expression profiling capitalizing on the differences between patients with and without diabetes is a good place to identify potential medical targets.

Effects of diabetes and cardiopulmonary bypass on expression of adherens junction proteins in human peripheral tissue

BACKGROUND

We investigated the changes in adherens junction proteins, such as vascular endothelial-cadherin and β-catenin, of skeletal muscle and vessels in patients with or without diabetes in the setting of cardiopulmonary bypass and cardiac operation.

METHODS

Skeletal muscle tissue samples were harvested pre- and post-cardiopulmonary bypass from nondiabetic (hemoglobin A1c: 5.4 ± 0.1), controlled diabetic (hemoglobin A1c: 6.3 ± 0.1), and uncontrolled diabetic patients (hemoglobin A1c: 9.6 ± 0.3) undergoing coronary artery bypass grafting operation (n = 8 per group). The expression/phosphorylation of adherens junction proteins vascular endothelial-cadherin and β-catenin were assessed by immunoblotting and immuno-histochemistry. Endothelial function of skeletal muscle arterioles was determined by videomicroscopy in response to the vasodilator substance P.

RESULTS

The protein expression of total vascular endothelial-cadherin was not changed at baseline or between pre-and post-cardiopulmonary bypass among groups. The pre-cardiopulmonary bypass level of phospho-vascular endothelial-cadherin was found to be significantly increased in the uncontrolled diabetic patients group compared with the nondiabetic or controlled diabetic groups (P < .05). The post-cardiopulmonary bypass levels of phospho-vascular endothelial-cadherin were significantly increased compared with pre-cardiopulmonary bypass in all groups (P < .05 each), and this increase was greater in the uncontrolled diabetic patients group than that of the nondiabetic or controlled diabetic groups (P < .05). Expression of basal β-catenin protein in the uncontrolled diabetic group was decreased compared with nondiabetic or controlled diabetic groups (P < .05). There were significant decreases in the β-catenin protein expression between pre- and post-cardiopulmonary bypass in all 3 groups (P < .05 each), and this decrease was greater in the uncontrolled diabetic patients group than the nondiabetic group (P < .05). There were decreases in the relaxation response of skeletal muscle arterioles to substance P after cardiopulmonary bypass in all 3 groups (P < .05), and this alteration was more pronounced in the uncontrolled diabetic patients (P < .05).

CONCLUSION

Uncontrolled diabetes causes inactivation and reduction in the expression of endothelial adherens junction proteins in the arterioles of skeletal muscle early after cardiopulmonary bypass. The enhanced phosphorylation of vascular endothelial-cadherin and degradation of β-catenin indicate deterioration of these proteins and damage of the cell-cell endothelial junctions, specifically in the diabetic peripheral vessels. These alterations may contribute to the increases in peripheral vascular permeability and endothelial dysfunction.

New continuous-flow total artificial heart and vascular permeability

BACKGROUND

We tested the short-term effects of completely nonpulsatile versus pulsatile circulation after ventricular excision and replacement with total implantable pumps in an animal model on peripheral vascular permeability.

METHODS

Ten calves underwent cardiac replacement with two HeartMate III continuous-flow rotary pumps. In five calves, the pump speed was rapidly modulated to impart a low-frequency pulse pressure in the physiologic range (10-25 mm Hg) at a rate of 40 pulses per minute (PP). The remaining five calves were supported with a pulseless systemic circulation and no modulation of pump speed (NP). Skeletal muscle biopsies were obtained before cardiac replacement (baseline) and on postoperative days (PODs) 1, 7, and 14. Skeletal muscle-tissue water content was measured, and morphologic alterations of skeletal muscle were assessed. VE-cadherin, phospho-VE-cadherin, and CD31 were analyzed by immunohistochemistry.

RESULTS

There were no significant changes in tissue water content and skeletal muscle morphology within group or between groups at baseline, PODs 1, 7, and 14, respectively. There were no significant alterations in the expression and/or distribution of VE-cadherin, phospho-VE-cadherin, and CD31 in skeletal muscle vasculature at baseline, PODs 1, 7, and 14 within each group or between the two groups, respectively. Although continuous-flow total artificial heart (CFTAH) with or without a pulse pressure caused slight increase in tissue water content and histologic damage scores at PODs 7 and 14, it failed to reach statistical significance.

CONCLUSIONS

There was no significant adherens-junction protein degradation and phosphorylation in calf skeletal muscle microvasculature after CFTAH implantation, suggesting that short term of CFTAH with or without pulse pressure did not cause peripheral endothelial injury and did not increase the peripheral microvascular permeability.

Pre-B-cell colony enhancing factor (PBEF) increases endothelial permeability in hypoxia/re-oxygenation model

OBJECTIVE

This study aims to explore the relationship between PBEF and VEGF and p-MLC and the mechanism of PBEF increasing permeability of endothelial cells in hypoxia/re-oxygenation.

METHODS

Hypoxia/re-oxygenation model was established and PBEF siRNA was synthesized. According to the different HUVEC treatment, it can be divided into normal control group, PBEF siRNA group; hypoxia (20 hours) and re-oxygenation (3 h) group, hypoxia (20 h) and re-oxygenation (6 h) group, hypoxia (20 h) and re-oxygenation (9 hours) group, hypoxia (20 h)/re-oxygenation (12 h). The expressions of PBEF, VEGF and p-MLC were tested by RT-PCR and Western blot.

RESULTS

The mRNA and protein expression of PBEF in PBEF siRNA group were significantly lower compared to liposome group and the negative controls (P < 0.05). The expression of PBEF protein in hypoxia/re-oxygenation group was significantly higher than the normal control group. It increased in the 3 h of re-oxygenation group, peaked at 9 h, until 12 h started to decline (P < 0.05). When the PBEF gene was knockdown, the expression of VEGF and p-MLC in hypoxia and re-oxygenation are significantly lower.

CONCLUSIONS

PBEF siRNA can effectively inhibit the expression of PBEF in endothelial cells. The expression of PBEF, VEGF and p-MLC were significantly higher in endothelial cell after Hypoxia/re-oxygenation. PBEF may change the permeability of endothelial cells by regulating the expression of VEGF and the phosphorylation of MLC.

Differential impairment of adherens-junction expression/phosphorylation after cardioplegia in diabetic versus non-diabetic patients

OBJECTIVES

Previous animal studies have demonstrated that endothelial adherens-junction molecules are significantly altered in animal myocardium and microvasculature after cardioplegia and cardiopulmonary bypass (CP/CPB). We investigated the effects of diabetes on expression/phosphorylation/localization of vascular endothelial (VE)-cadherin, β- and γ-catenin in human atrial myocardium and coronary vasculature in the setting of CP/CPB.

METHODS

Right atrial tissue was harvested pre- and post-CP/CPB from non-diabetic (ND) [haemoglobin A1c (HbA1c): 5.4 ± 0.15], controlled (CDM) (HbA1c: 6.3 ± 0.14) and uncontrolled diabetic (UDM) (HbA1c: 9.9 ± 0.72) patients (n = 10/group). Expression/phosphorylation/localization of VE-cadherin, β- and γ-catenin were assessed by immunoblotting, immunoprecipitation and immunohistochemistry. In vitro atrial microvascular reactivity was assessed by videomicroscopy in response to the endothelium-dependent vasodilator adenosine 5'-diphosphate (ADP).

RESULTS

There were no significant differences in VE-cadherin protein expression between pre- and post-CP/CPB among groups. There were significant decreases in VE-cadherin densities in vessels of the UDM group versus the ND group at baseline or post-CP/CPB, respectively (P < 0.05). The level of basal phosphorylated VE-cadherin tends to be higher in the UDM compared with the ND group (P < 0.05). CP/CPB induced more phosphorylation of VE-cadherin in all groups (versus pre-CP/CPB; P < 0.05, respectively) and this effect was more pronounced in the UDM group (P < 0.05 versus ND or CDM). The protein levels of both catenins (β and γ) were lower in post-CP/CPB in UDM than ND patients (P < 0.05). There were significant decreases in vasodilatory response to endothelial-dependent vasodilator ADP after CP/CPB (P < 0.05). This alteration was more pronounced in UDM patients (P < 0.05).

CONCLUSIONS

These data suggest that poorly controlled diabetes down-regulates endothelial adherens-junction protein activation/expression/localization in the setting of CP/CPB. The increased tyrosine phosphorylation and deterioration of VE-cadherin indicate the damage of the cell-cell endothelial junctions in the diabetic vessels undergoing CP/CPB and cardiac surgery. These alterations may lead to increase in vascular permeability and endothelial dysfunction and affect outcomes in diabetic patients after cardiac surgery.

MCARD-mediated gene transfer of GRK2 inhibitor in ovine model of acute myocardial infarction

β-Adrenergic receptor (βAR) dysfunction in acute myocardial infarction (MI) is associated with elevated levels of the G-protein-coupled receptor kinase-2 (GRK2), which plays a key role in heart failure progression. Inhibition of GRK2 via expression of a peptide βARKct transferred by molecular cardiac surgery with recirculating delivery (MCARD) may be a promising intervention. Five sheep underwent scAAV6-mediated MCARD delivery of βARKct, and five received no treatment (control). After a 3-week period, the branch of the circumflex artery (OM1) was ligated. Quantitative PCR data showed intense βARKct expression in the left ventricle (LV). Circumferential fractional shortening was 23.4 ± 7.1 % (baseline) vs. -2.9 ± 5.2 % (p < 0.05) in the control at 10 weeks. In the MCARD-βARKct group, this parameter was close to baseline. The same trend was observed with LV wall thickening. Cardiac index fully recovered in the MCARD-βARKct group. LV end-diastolic volume and LV end-diastolic pressure did not differ in both groups. MCARD-mediated βARKct gene expression results in preservation of regional and global systolic function after acute MI without arresting progressive ventricular remodeling.

Changes in microvascular reactivity after cardiopulmonary bypass in patients with poorly controlled versus controlled diabetes

BACKGROUND

We investigated the effects of cardiopulmonary bypass (CPB) on peripheral arteriolar reactivity and associated signaling pathways in poorly controlled (UDM), controlled (CDM), and case-matched nondiabetic (ND) patients undergoing coronary artery bypass grafting (CABG).

METHODS AND RESULTS

Skeletal muscle arterioles were harvested before and after CPB from the UDM patients (hemoglobin A1c [HbA1c]=9.0 ± 0.3), the CDM patients (HbA1c=6.3 ± 0.15), and the ND patients (HbA1c=5.2 ± 0.1) undergoing CABG surgery (n=10/group). In vitro relaxation responses of precontracted arterioles to endothelium-dependent vasodilators adenosine 5'-diphosphate (ADP) and substance P and the endothelium-independent vasodilator sodium nitroprusside (SNP) were examined. The baseline responses to ADP, substance P, and SNP of arterioles from the UDM patients were decreased as compared with microvessels from the ND or CDM patients (P<0.05). The post-CPB relaxation responses to ADP and substance P were significantly decreased in all 3 groups compared with pre-CPB responses (P<0.05). However, these decreases were more pronounced in the UDM group (P<0.05). The post-CPB response to SNP was significantly decreased only in the UDM group, not in the other 2 groups compared with pre-CPB. The expression of protein kinase C (PKC)-α, PKC-β, protein oxidation, and nitrotyrosine in the skeletal muscle were significantly increased in the UDM group as compared with those of ND or CDM groups (P<0.05).

CONCLUSIONS

Poorly controlled diabetes results in impaired arteriolar function before and after CPB. These alterations are associated with the increased expression/activation of PKC-α and PKC-β and enhanced oxidative and nitrosative stress.

Decreased coronary microvascular reactivity after cardioplegic arrest in patients with uncontrolled diabetes mellitus

BACKGROUND

We investigated the effects of cardioplegic arrest and reperfusion on coronary arteriolar responses to endothelium-dependent and -independent vasodilators and associated signaling pathways in uncontrolled diabetic, well controlled diabetic, and case-matched nondiabetic patients undergoing coronary artery bypass graft surgery.

METHODS

Coronary arterioles from harvested right atrial tissues were dissected pre- and post-cardioplegic arrest and reperfusion from uncontrolled diabetic (n = 10; hemoglobin A1c = 9.3 ± 0.3), well controlled diabetic (n = 10; hemoglobin A1c = 6.2 ± 0.2), and nondiabetic patients (n = 10; hemoglobin A1c = 5.1 ± 0.1) undergoing coronary artery bypass graft surgery.

RESULTS

The baseline microvascular response to adenosine 5'-diphosphate, substance P, and sodium nitroprusside of arterioles from uncontrolled diabetic patients were decreased compared to the respective response from nondiabetic or well controlled diabetic patients (P < .05). The vasodilatory responses to adenosine 5'-diphosphate and substance P after cardioplegic arrest and reperfusion were significantly decreased in all 3 groups compared to pre-cardioplegic arrest and reperfusion responses (P < .05). However, these decreases were more pronounced in the uncontrolled diabetic group (P < .05). The expression of protein kinase C-α, protein kinase C-β, and protein oxidation in atrial tissues was significantly increased in the uncontrolled diabetic group compared to the nondiabetic or controlled diabetes groups.

CONCLUSION

Uncontrolled diabetes is associated with endothelium-dependent and -independent vascular dysfunction of coronary arterioles. In addition, uncontrolled diabetes worsens the recovery of coronary arteriolar function after cardioplegic arrest and reperfusion. These alterations are associated with an increased expression/activation of protein kinase C-α and protein kinase C-β and enhanced oxidative stress.

Whole blood transcriptomics in cardiac surgery identifies a gene regulatory network connecting ischemia reperfusion with systemic inflammation

Background

Cardiac surgery with cardiopulmonary bypass (CS/CPB) is associated with increased risk for postoperative complications causing substantial morbidity and mortality. To identify the molecular mechanisms underlying CS/CPB-induced pathophysiology we employed an integrative systems biology approach using the whole blood transcriptome as the sentinel organ.

Methodology/Principal Findings

Total RNA was isolated and globin mRNA depleted from whole blood samples prospectively collected from 10 patients at time points prior (0), 2 and 24 hours following CS/CPB. Genome-wide transcriptional analysis revealed differential expression of 610 genes after CS/CPB (p<0.01). Among the 375 CS/CPB-upregulated genes, we found a gene-regulatory network consisting of 50 genes, reminiscent of activation of a coordinated genetic program triggered by CS/CPB. Intriguingly, the highly connected hub nodes of the identified network included key sensors of ischemia-reperfusion (HIF-1alpha and C/EBPbeta). Activation of this network initiated a concerted inflammatory response via upregulation of TLR-4/5, IL1R2/IL1RAP, IL6, IL18/IL18R1/IL18RAP, MMP9, HGF/HGFR, CalgranulinA/B, and coagulation factors F5/F12 among others. Differential regulation of 13 candidate genes including novel, not hitherto CS/CBP-associated genes, such as PTX3, PGK1 and Resistin, was confirmed using real-time quantitative RT-PCR. In support of the mRNA data, differential expression of MMP9, MIP1alpha and MIP1beta plasma proteins was further confirmed in 34 additional patients.

Conclusions

Analysis of blood transcriptome uncovered critical signaling pathways governing the CS/CPB-induced pathophysiology. The molecular signaling underlying ischemia reperfusion and inflammatory response is highly intertwined and includes pro-inflammatory as well as cardioprotective elements. The herein identified candidate genes and pathways may provide promising prognostic biomarker and therapeutic targets.

Decreased contractile response to endothelin-1 of peripheral microvasculature from diabetic patients

BACKGROUND

We compared the contractile responses to endothelin-1 (ET-1) with and without the inhibition of ET-A receptors and protein kinase C-alpha (PKC-α) in the human peripheral microvasculature of diabetic and case-matched, nondiabetic patients.

METHODS

Chest wall skeletal muscle was harvested from patients with and without diabetics undergoing cardiac surgery. Peripheral arterioles (90-180 μm in diameter) were dissected from the harvested tissue. Microvascular constriction was assessed by videomicroscopy in response to ET-1 with and without an endothelin-A (ET-A) receptor antagonist, an endothelin B (ET-B) antagonist, or a PKC-α inhibitor.

RESULTS

ET-1 induced a dose-dependent contractile response of skeletal muscle arterioles from diabetic and nondiabetic patients. The contractile response of diabetic arterioles from both prebypass and postbypass to ET-1 (10(-9) mol/L) was decreased compared with those of nondiabetic patients (P < .05). The contractile responses of microvessels of both diabetics and nondiabetics to ET-1 were inhibited in the presence of either ET-A receptor antagonist BQ123 (10(-7) mol/L) or the PKC-α inhibitor safingol (2 × 10(-5) mol/L, P < .05, respectively). In contrast, the ET-1-induced vasoconstriction was not affected by the administration of the ET-B receptor antagonist BQ788 (10(-7) mol/L). There were no differences in skeletal muscle levels of the ET-A and ET-B receptors between diabetic and nondiabetic groups.

CONCLUSION

Diabetic patients demonstrated a decreased contractile response to ET-1 in human peripheral microvasculature. The contractile response of diabetic vessels to ET-1 occurs via activation of ET-A receptors and PKC-α. These results provide novel mechanisms of ET-1-induced contraction in vasomotor dysfunction in patients with diabetes.