ABSTRACT
AIMS: Pulmonary hypertension (PH) is characterised by an increase in pulmonary arterial pressure, ultimately leading to right ventricular failure and death. We have previously shown that nerve growth factor (NGF) plays a critical role in PH. Our objectives here were to determine whether NGF controls Connexin-43 (Cx43) expression and function in the pulmonary arterial smooth muscle, and whether this mechanism contributes to NGF-induced pulmonary artery hyperreactivity. METHODS AND RESULTS: NGF activates its TrkA receptor to increase Cx43 expression, phosphorylation, and localization at the plasma membrane in human pulmonary arterial smooth muscle cells, thus leading to enhanced activity of Cx43-dependent GAP junctions as shown by Lucifer Yellow dye assay transfer and fluorescence recovery after photobleaching -FRAP- experiments. Using both in vitro pharmacological and in vivo SiRNA approaches, we demonstrate that NGF-dependent increase in Cx43 expression and activity in the rat pulmonary circulation causes pulmonary artery hyperreactivity. We also show that, in a rat model of PH induced by chronic hypoxia, in vivo blockade of NGF or of its TrkA receptor significantly reduces Cx43 increased pulmonary arterial expression induced by chronic hypoxia and displays preventive effects on pulmonary arterial pressure increase and right heart hypertrophy. CONCLUSIONS: Modulation of Cx43 by NGF in pulmonary arterial smooth muscle cells contributes to NGF-induced alterations of pulmonary artery reactivity. Since NGF and its TrkA receptor play a role in vivo in Cx43 increased expression in PH induced by chronic hypoxia, these NGF/Cx43-dependent mechanisms may therefore play a significant role in human PH pathophysiology.
Subject(s)
Connexin 43 , Myocytes, Smooth Muscle , Nerve Growth Factor , Pulmonary Artery , Animals , Humans , Male , Rats , Cells, Cultured , Connexin 43/metabolism , Gap Junctions/metabolism , Gap Junctions/drug effects , Hypertension, Pulmonary/metabolism , Muscle, Smooth, Vascular/metabolism , Muscle, Smooth, Vascular/drug effects , Myocytes, Smooth Muscle/metabolism , Myocytes, Smooth Muscle/drug effects , Nerve Growth Factor/metabolism , Phosphorylation , Pulmonary Artery/drug effects , Pulmonary Artery/metabolism , Pulmonary Artery/pathology , Rats, Sprague-Dawley , Rats, Wistar , Receptor, trkA/metabolismABSTRACT
BACKGROUND AND PURPOSE: Pulmonary hypertension (PH) is a cardiovascular disease characterised by an increase in pulmonary arterial (PA) resistance leading to right ventricular (RV) failure. Reactive oxygen species (ROS) play a major role in PH. OP2113 is a drug with beneficial effects on cardiac injuries that targets mitochondrial ROS. The aim of the study was to address the in vivo therapeutic effect of OP2113 in PH. EXPERIMENTAL APPROACH: PH was induced by 3 weeks of chronic hypoxia (CH-PH) in rats treated with OP2113 or its vehicle via subcutaneous osmotic mini-pumps. Haemodynamic parameters and both PA and heart remodelling were assessed. Reactivity was quantified in PA rings and in RV or left ventricular (LV) cardiomyocytes. Oxidative stress was detected by electron paramagnetic resonance and western blotting. Mitochondrial mass and respiration were measured by western blotting and oxygraphy, respectively. KEY RESULTS: In CH-PH rats, OP2113 reduced the mean PA pressure, PA remodelling, PA hyperreactivity in response to 5-HT, the contraction slowdown in RV and LV and increased the mitochondrial mass in RV. Interestingly, OP2113 had no effect on haemodynamic parameters, both PA and RV wall thickness and PA reactivity, in control rats. Whereas oxidative stress was evidenced by an increase in protein carbonylation in CH-PH, this was not affected by OP2113. CONCLUSION AND IMPLICATIONS: Our study provides evidence for a selective protective effect of OP2113 in vivo on alterations in both PA and RV from CH-PH rats without side effects in control rats.
Subject(s)
Heart Failure , Hypertension, Pulmonary , Ventricular Dysfunction, Right , Rats , Animals , Hypertension, Pulmonary/metabolism , Reactive Oxygen Species/metabolism , Heart Ventricles/metabolism , Pulmonary Artery , Heart Failure/metabolism , Hypoxia/complications , Hypoxia/drug therapy , Hypoxia/metabolism , Ventricular Dysfunction, Right/metabolism , Ventricular Function, Right , Disease Models, AnimalABSTRACT
Pulmonary hypertension (PH) is a severe and multifactorial disease characterized by a progressive elevation of pulmonary arterial resistance and pressure due to remodeling, inflammation, oxidative stress, and vasoreactive alterations of pulmonary arteries (PAs). Currently, the etiology of these pathological features is not clearly understood and, therefore, no curative treatment is available. Since the 1990s, hydrogen sulfide (H2S) has been described as the third gasotransmitter with plethoric regulatory functions in cardiovascular tissues, especially in pulmonary circulation. Alteration in H2S biogenesis has been associated with the hallmarks of PH. H2S is also involved in pulmonary vascular cell homeostasis via the regulation of hypoxia response and mitochondrial bioenergetics, which are critical phenomena affected during the development of PH. In addition, H2S modulates ATP-sensitive K+ channel (KATP) activity, and is associated with PA relaxation. In vitro or in vivo H2S supplementation exerts antioxidative and anti-inflammatory properties, and reduces PA remodeling. Altogether, current findings suggest that H2S promotes protective effects against PH, and could be a relevant target for a new therapeutic strategy, using attractive H2S-releasing molecules. Thus, the present review discusses the involvement and dysregulation of H2S metabolism in pulmonary circulation pathophysiology.
