Sympathetic nervous system hyperactivity-induced oxidative stress promoting endothelial dysfunction is dependent on the NADPH oxidases/SGLT2 crosstalk: potential role in cardiogenic shock

Background

Hyperactivity of the sympathetic nervous system (SNS) promotes cardiac dysfunction, that can contribute to heart failure and even cardiogenic shock. Endothelial dysfunction associated with increased formation of reactive oxygen species (ROS) has been suggested to promote cardiac dysfunction and heart failure. Our previous results showed that SGLT2 and ROS derived from endothelial NADPH oxidases contribute to cardiac dysfunction.

Purpose

Therefore, this study examined whether cardiogenic shock and hyperactivation of the SNS involve NADPH oxidases and SGLT2 in the development of endothelial dysfunction using in vitro and in vivo approaches.

Methods

Peripheral blood from patients with cardiogenic shock and healthy controls was drawn by vein puncture into tubes containing sodium citrate. Cultured human microvascular endothelial cells (HMEC-1) were stimulated with either 100 nM of the β-adrenergic agonist isoproterenol or with heparinized (10 U/ml) patient plasma. Male wild-type mice and mice lacking the NADPH oxidase subunit p22phox in the endothelium (p22phox ecKO, 11-week-old) were treated with isoproterenol (100 mg/kg) for five consecutive days and sacrificed at day 14. ROS levels were assessed by dihydroethidium fluorescence, and the expression levels of target genes and proteins by RT-qPCR and Western blot, respectively. siRNA approaches were used to down-regulate the NADPH oxidase subunit p22phox or SGLT2.

Results

Exposure of HMEC-1 to either plasma from patients suffering from cardiogenic shock or isoproterenol stimulated the formation of ROS. ROS levels were reduced by N-acetylcysteine (an antioxidant) and silencing of p22phox, by empagliflozin (a selective SGLT2 inhibitor) and silencing of SGLT2 as well as by metoprolol (a beta1 adrenergic receptor antagonist) and ICI-118,551 (a beta2 adrenergic receptor antagonist). Cardiogenic shock patient plasma and isoproterenol upregulated the NADPH oxidase subunits p22phox and Nox4 as well as SGLT2. These responses were prevented by silencing of either p22phox or SGLT2, and by empagliflozin. In addition to improved cardiac function and blunted SGLT2 expression, p22phox ecKO mice were protected against isoproterenol-induced endothelial dysfunction and senescence, characterized by upregulation of eNOS, nitrotyrosine, VCAM-1 and p16 in the left ventricle.

Conclusion

SNS hyperactivity and cardiogenic shock-derived patient plasma cause a feed forward loop between NADPH oxidases and SGLT2, promoting pro-oxidant responses and endothelial dysfunction via activation of both beta1 and beta2 adrenergic receptors. The NADPH oxidase/SGLT2 crosstalk also contributes to SNS hyperactivity-induced senescence, cardiac and endothelial dysfunction. Thus, the endothelial NADPH oxidases/SGLT2 crosstalk appears to have a major role in cardiac diseases associated with SNS hyperactivity such as cardiogenic shock.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Deutsches Herzzentrum München

A miRNA derived from the 17/92 cluster is a novel player in programming pulmonary hypertension in response to gestational hypoxia via NADPH oxidases and the mTOR pathway

Background

Gestational hypoxia can lead to intrauterine growth restriction (IUGR) and programming of cardiovascular diseases in adulthood via different, although not completely understood, epigenetic mechanisms. We have previously shown that reactive oxygen species (ROS) derived from NADPH oxidases contribute to hypoxia induced pulmonary hypertension (PH). However, their role in disease programming by gestational hypoxia is not resolved.

Purpose

We aimed to elucidate the role of NADPH oxidases and redox sensitive miRNAs in the cardiovascular response of adult offspring to transient gestational hypoxia.

Methods

Wildtype (WT) and nmf333 mice, lacking a functional p22phox dependent NADPH oxidase, were exposed to gestational hypoxia from E10.5 to E11.5. Embryos and adult offspring were analyzed by functional, immunohistochemical and molecular methods including mRNA and miRNA profiling. miRNA mimics or inhibitors were applied in vivo and in vitro using embryoid bodies (EBs). Heart samples from patients with right heart disease associated with congenital heart disease (CHD) were used to validate target miRNA expression.

Results

Transient gestational hypoxia was sufficient to induce IUGR in embryos and pulmonary hypertension (PH) characterized by right ventricular hypertrophy, increased right ventricular pressure and pulmonary vascular remodeling in adult offspring from WT mice while p22phox-deficient nmf333 mice were protected. Cardiac mRNA and miRNA profiling followed by qPCR validation identified several single miRNAs derived from the 17/92 miRNA cluster as downregulated by gestational hypoxia and NADPH oxidases in embryos and adult offspring hearts. In vitro analyses using EBs validated a single miRNA from this cluster to be sufficient to induce cardiac differentiation in response to hypoxia and p22phox, and target analyses identified the mTOR pathway as dysregulated. Treatment with an inhibitor targeting this miRNA was sufficient to induce PH in adult mice, while treating offspring derived from gestational hypoxia pregnancies with an miRNA mimic prevented the development of PH in the adult and dysregulation of the mTOR pathway. Importantly, expression of this single miRNA from the miRNA 17/92 cluster was negatively correlated to right ventricular pressure in CHD patients.

Conclusions

In this study, we demonstrate that gestational hypoxia programs PH in adulthood by upregulating NADPH oxidases and downregulating miRNAs derived from the 17/92 cluster subsequently affecting the mTOR pathway. Since dysregulation of a single miRNA from this cluster induced not only PH but was also associated with right ventricular pressure in CHD patients, these findings might open novel options for diagnosis, prevention and treatment of right heart disease.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): DZHK (German Centre for Cardiovascular Research)

Endothelial NADPH oxidases protect against sympathetic nervous system hyperactivity-induced cardiac dysfunction and remodeling in mice: contribution of SGLT2

Background

NADPH oxidase-derived reactive oxygen species (ROS) contribute to cardiac dysfunction, often characterized by coronary microvascular dysfunction, an inflammatory response and cardiomyocyte hypertrophy. Hyperactivity of the sympathetic nervous system (SNS) induces oxidative stress, promoting cardiac dysfunction and the development of heart failure. Selective inhibitors of sodium-glucose co-transporter 2 (SGLT2), have shown remarkable cardioprotective effects in clinical studies. Recently, SGLT2 inhibitors have been reported to prevent endothelial dysfunction and pro-inflammatory responses in endothelial cells in response to angiotensin II involving NADPH oxidases.

Purpose

Therefore, the aim of the study was to determine whether endothelial NADPH oxidases promote SNS-induced cardiac dysfunction and to clarify the role of SGLT2.

Methods

Male wild-type mice and mice lacking the NADPH oxidase subunit p22phox in the endothelium (p22phox ecKO, 11-week-old) were treated with isoproterenol (100 mg/kg) for five consecutive days and sacrificed at day 14. Hemodynamic measurements of left (LV) and right (RV) ventricles were performed by a transthoracic approach. Heart tissue sections were stained with Sirius red to evaluate fibrosis and wheat germ agglutinin to assess cardiomyocyte size. Cultured human microvascular endothelial cells (HMEC-1) were stimulated with 100 nM isoproterenol and ROS levels were assessed by dihydroethidium fluorescence. The expression level of target genes and proteins was assessed by quantitative real-time PCR and Western blot, respectively. siRNA approaches were used to down-regulate either the NADPH oxidase subunit p22phox or SGLT2.

Results

The isoproterenol treatment increased LV and RV systolic pressures in wild-type mice but not in p22phox ecKO mice. p22phox ecKO mice were protected against isoproterenol-induced fibrosis, cardiac remodeling characterized by upregulation of mRNA levels of ANP, BNP and β-MHC, and pulmonary congestion. LV remodeling was associated with upregulation of the NADPH oxidase subunits p22phox, Nox2, and Nox4 as well as of SGLT2 in wild-type mice, however no such effects were observed in p22phox ecKO mice. Exposure of HMEC-1 to isoproterenol stimulated the formation of ROS and caused an upregulation of p22phox and SGLT2 protein levels in a time- and concentration-dependent manner. No such effects were observed following silencing of either p22phox or SGLT2, or use of a selective SGLT2 inhibitor.

Conclusion

Deletion of the NADPH oxidase subunit p22phox in the endothelium protected against SNS hyperactivity induced LV cardiac dysfunction and remodeling, and prevented upregulation of SGLT2. Since depletion of SGLT2 prevented the pro-oxidant response to isoproterenol in endothelial cells, the endothelial NADPH oxidase/SGLT2 pathway seems to have a prominent role in promoting cardiac remodeling and dysfunction in SNS hyperactivity.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Deutsches Herzzentrum München

Recombination events between the p47-phox gene and its highly homologous pseudogenes are the main cause of autosomal recessive chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited disease caused by defects in the superoxide-generating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase of phagocytes. Genetic lesions in any of 4 components of this antimicrobial enzyme have been detected. Family-specific mutations are found in 3 of 4 forms of CGD due to deficiencies of the gp91-phox, p22-phox, and p67-phox genes. In p47-phox-deficient CGD (autosomal recessive form A47 degrees ) patients, a GT deletion (triangle upGT) at the beginning of exon 2 of the p47-phox gene has been reported in 19 of 20 alleles. This GT deletion is also characteristic for the recently identified p47-phox pseudogenes. To explore a possible link between these findings, a sequence analysis of 28 unrelated, racially diverse A47 degrees CGD patients and 37 healthy individuals was performed. The GT deletion in exon 2 was present on all alleles in 25 patients. Only 3 patients but all healthy individuals contained the GTGT and triangle upGT sequences. A total of 22 patients carried additional pseudogene-specific intronic sequences on all alleles, either only in intron 1 or in intron 1 and intron 2, which lead to different types of chimeric DNA strands. It is concluded that recombination events between the p47-phox gene and its highly homologous pseudogenes result in the incorporation of triangle upGT into the p47-phox gene, thereby leading to the high frequency of GT deletion in A47 degrees CGD patients. (Blood. 2000;95:2150-2156)

In vitro antitumor activity of 2'-deoxy-5-fluorouridine-monoclonal antibody conjugates

5-Fluorouracil (5-FU) is an anticancer drug used in patients for the treatment of gastric and breast cancer and used either alone or in combination with methotrexate is one of the few drugs with some effect on colon cancer. 2'-Deoxy-5-fluorouridine (5-FUdr) (1) is an analogue based on 5-FU and can be covalently linked to a murine anti-Ly-2.1 monoclonal antibody (mAb) with the active ester derivative of 2'-deoxy-5-fluoro-3'-O-(carboxypropanoyl)uridine (5-FUdr-succ) (4). Such immunoconjugates can contain up to 42 residues of drug, although the most antibody activity was retained when substitution ratios were between 10 and 25 molecules of drug to mAb. In a cytotoxicity assay, 50% inhibition of [3H]deoxyuridine incorporation (IC50) with a murine Ly-2.1+ve thymoma cell line was 6 nM for 5-FUdr-anti-Ly-2.1, which is 12-fold more than that for free 5-FUdr (IC50 = 0.51 nM) but similar to that of 5-FUdr-succ (IC50 = 5.2 nM). The 5-FUdr-monoclonal antibody conjugates (5-FUdr-mAb) were 100-fold more active on the Ly-2.1+ve E3 cell line than on the Ly-2.1-ve BW5147 OU- cell line. The high in vitro activity and specificity of 5-FUdr-MoAb conjugates indicates that potent in vivo activity of these conjugates should be expected.