This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Alcoholic cardiomyopathy (ACM) resulting from excess alcohol consumption is an important cause of heart failure (HF). Although it is assumed that the cardiotoxicity of the ethanol (EtOH)-metabolite acetaldehyde (ACA) is central for its development and progression, the exact mechanisms remain obscure. Murine cardiomyocytes (CMs) exposed to ACA or EtOH showed increased superoxide (O2•−) levels and decreased mitochondrial polarization, both being normalized by NADPH oxidase (NOX) inhibition. C57BL/6 mice and mice deficient for the ACA-degrading enzyme mitochondrial aldehyde dehydrogenase (ALDH-2−/−) were fed a 2% EtOH diet for 5 weeks creating an ACA-overload. 2% EtOH-fed ALDH-2−/− mice exhibited a decreased cardiac function, increased heart-to-body and lung-to-body weight ratios, increased cardiac levels of the lipid peroxidation product malondialdehyde (MDA) as well as increased NOX activity and NOX2/glycoprotein 91phox (NOX2/gp91phox) subunit expression compared to 2% EtOH-fed C57BL/6 mice. Echocardiography revealed that ALDH-2−/−/gp91phox−/− mice were protected from ACA-overload-induced HF after 5 weeks of 2% EtOH-diet, demonstrating that NOX2-derived O2•− contributes to the development of ACM. Translated to human pathophysiology, we found increased gp91phox expression in endomyocardial biopsies of ACM patients. In conclusion, ACM is promoted by ACA-driven mitochondrial dysfunction and can be improved by ablation of NOX2/gp91phox. NOX2/gp91phox therefore might be a potential pharmacological target to treat ACM.

Pulmonary embolism (PE) results from deep vein thrombosis (DVT) and can lead to chronic thromboembolic pulmonary hypertension (CTEPH) involving vascular dysfunction. Mechanisms are incompletely understood, in part due to lack of mouse models. We induced PE in C57BL/6 mice by intravenous injection of thrombin (166 U/kg BW), confirmed by a sudden bradycardia, bradypnea, and an increase in pulmonary artery (PA) pressure observed by high-frequency ultrasound. While symptoms resolved rapidly after single thrombin application, repeated PEs resulted in sustained PA-pressure increase, increased PA superoxide formation assessed by oxidative fluorescent microtopography, increased PA gp91phox expression, and endothelial dysfunction assessed by isometric tension studies of isolated PA segments after 24 hours. DVT was modeled in C57BL/6 mice by ligation of the inferior vena cava (IVC). Importantly, small pulmonary emboli could be detected along with a mild phenotype of PA endothelial dysfunction and oxidative stress in the absence of PA-pressure elevation. mRNA expression of plasminogen activator inhibitor-1 was increased in PAs of mice with recurrent PE after repetitive thrombin injections and to a lesser extent in DVT mice. In summary, our data suggest that PA endothelial dysfunction, induced by gp91phox-derived ROS, is an early event upon repetitive PE. This phenomenon might help to elucidate the mechanisms of PA dysfunction in the pathogenesis of CTEPH.

Aims. The neutrophil recruiting cytokine Interleukin-17A (IL-17A) is a key component in vascular dysfunction and arterial hypertension. Moreover, IL-17A has a central role for the vascular infiltration of myeloid cells into the arterial wall in Angiotensin II-induced vascular inflammation. The intention of our study was to analyze the impact of T cell-derived IL-17A on hypertension, vascular function, and inflammation. Methods and Results. Chronic IL-17A overexpression in T cells (CD4-IL-17Aind/+ mice) resulted in elevated reactive oxygen species in the peripheral blood and a significant vascular dysfunction compared to control mice. The vascular dysfunction seen in the CD4-IL-17Aind/+ mice was only accompanied by a modest and nonsignificant accumulation of inflammatory cells within the vessel wall. Therefore, infiltrating myeloid cells did not serve as an explanation of the vascular dysfunction seen in a chronic IL-17A-driven mouse model. In addition to vascular dysfunction, CD4-IL-17Aind/+ mice displayed vascular fibrosis with highly proliferative fibroblasts. This fibroblast proliferation was induced by exposure to IL-17A as confirmed by in vitro experiments with primary murine fibroblastic cells. We also found that the ⋅NO/cGMP pathway was downregulated in the vasculature of the CD4-IL-17Aind/+ mice, while levels of protein tyrosine kinase 2 (PYK2), an oxidative stress-triggered process associated with T cell activation, were upregulated in the perivascular fat tissue (PVAT). Conclusions. Our data demonstrate that T cell-derived IL-17A elicits vascular dysfunction by mediating proliferation of fibroblasts and subsequent vascular fibrosis associated with PYK2 upregulation.

Aims Heart failure (HF) ensuing myocardial infarction (MI) is characterized by the initiation of a systemic inflammatory response. We aimed to elucidate the impact of myelomonocytic cells and their activation by angiotensin II on vascular endothelial function in a mouse model of HF after MI. Methods and results HF was induced in male C57BL/6J mice by permanent ligation of the left anterior descending coronary artery. Compared to sham, HF mice had significantly impaired endothelial function accompanied by enhanced mobilization of Sca-1+c-Kit+ haematopoietic stem cells and Sca-1−c-Kit+ common myeloid and granulocyte-macrophage progenitors in the bone marrow as well as increased vascular infiltration of CD11b+Ly6G−Ly6Chigh monocytes and accumulation of CD11b+ F4/80+ macrophages, assessed by flow cytometry. Using mice with Cre-inducible expression of diphtheria toxin receptor in myeloid cells, we selectively depleted lysozyme M+ myelomonocytic cells for 10 days starting 28 days after MI. While the cardiac phenotype remained unaltered until 38 days post-MI, myeloid cell depletion attenuated vascular accumulation of Nox2+CD45+ cells, endothelial dysfunction, oxidative stress, and vascular expression of adhesion molecules and angiotensin II receptor type 1 (AT1R). Pharmacological blockade of this receptor for 4 weeks did not significantly alter cardiac function, but mimicked the effects of myeloid cell depletion: telmisartan (20 mg/kg/day, fed to C57BL/6J mice) diminished bone marrow myelopoesis and myeloid reactive oxygen species production, attenuated endothelial leucocyte rolling and vascular accumulation of CD11b+Ly6G−Ly6Chigh monocytes and macrophages, resulting in improved vascular function with less abundance of Nox2+CD45+ cells. Conclusion Endothelial dysfunction in HF ensuing MI is mediated by inflammatory Nox2+ myeloid cells infiltrating the vessel wall that can be targeted by AT1R blockade.