Pulmonary hypertension is a complex and heterogeneous condition with five main subtypes (groups). This review focuses on pulmonary hypertension caused by chronic hypoxia (hypoxic pulmonary hypertension, HPH, group 3). It is based mainly on our own experimental work, especially our collaboration with the group of Professor Herget, whose fifth anniversary of death we commemorate. We have found that oxidation and degradation of the extracellular matrix (ECM) in vitro, in either the presence or the absence of pro-inflammatory cells, activate vascular smooth muscle cell (VSMC) proliferation. Significant changes in the ECM of pulmonary arteries also occurred in vivo in hypoxic rats, namely a decrease in collagen VI and an increase in matrix metalloproteinase 9 (MMP-9) in the tunica media, which may also contribute to the growth activation of VSMCs. The proliferation of VSMCs was also enhanced in their co-culture with macrophages, most likely due to the paracrine production of growth factors in these cells. However, hypoxia itself has a dual effect: on the one hand, it can activate VSMC proliferation and hyperplasia, but on the other hand, it can also induce VSMC hypertrophy and increased expression of contractile markers in these cells. The influence of hypoxia-inducible factors, microRNAs and galectin-3 in the initiation and development of HPH, and the role of cell types other than VSMCs (endothelial cells, adventitial fibroblasts) are also discussed. Keywords: Vasoconstriction, Remodeling, Oxidation, Degradation, Extracellular matrix, Collagen, Proteolytic enzymes, Metalloproteinases, Macrophages, Mast cells, Smooth muscle cells, Endothelial cells, Fibroblasts, Mesenchymal stem cells, Hypoxia-inducible factor, microRNA, Galectins, Hyperplasia, Hypertrophy, Therapy of hypoxic pulmonary hypertension.

• MeSH
• Hypoxia * metabolism   MeSH
• Humans MeSH
• Myocytes, Smooth Muscle * metabolism   pathology   MeSH
• Hypertension, Pulmonary * metabolism   pathology   MeSH
• Cell Proliferation MeSH
• Muscle, Smooth, Vascular * metabolism   pathology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

Adverse events during the perinatal period are associated with an increased risk to develop cardiometabolic diseases later in life. We established a murine model to study long-term effects of perinatal hypoxia (PH) on the pulmonary circulation. We previously demonstrated that PH led to an impaired regulation of pulmonary vascular tone in adulthood, linked to alterations in K+ channels in males and in the nitric oxide (NO)/cyclic guanosine monophosphate pathway in females. Moreover, simultaneous administration of inhaled NO (iNO) during PH exposure prevented adverse effects of PH on adult pulmonary vasculature in females. The present study showed that PH induced a significant increase in right ventricular pressure in males and females, and an enhanced sensitivity to acute hypoxia in females. PH significantly reduced acetylcholine-induced relaxation in pulmonary artery, to a greater extent in females than in males. PH led to right ventricular hypertrophy in adulthood, appearing earlier in males than in females. Morphometric measurements showed a significant increase in the number of 25-75-µm pulmonary vessels in male lungs following PH, probably resulting in increased pulmonary vascular resistance. The effects of prolonged hypoxia in adulthood differed between males and females. Perinatal iNO during PH prevented PH-induced alterations in the cardiopulmonary system, whereas perinatal iNO alone could have some adverse effects. Therefore, PH led to long-lasting alterations in the regulation of adult pulmonary circulation, which vary between males and females. In males, the increased pulmonary vascular resistance was associated with morphological changes besides functional alterations, whereas females showed an important pulmonary vascular dysfunction. Keywords: Perinatal hypoxia, Pulmonary circulation, Endothelium-dependent relaxation, Phosphodiesterases, Sex differences.

• MeSH
• Pulmonary Artery metabolism   physiopathology   drug effects   MeSH
• Vascular Resistance physiology   MeSH
• Hypoxia * physiopathology   metabolism   MeSH
• Disease Models, Animal MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Animals, Newborn MeSH
• Nitric Oxide metabolism   MeSH
• Pulmonary Circulation * physiology   MeSH
• Sex Characteristics MeSH
• Sex Factors MeSH
• Pregnancy MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Nitric Oxide MeSH

Remodeling of the distal pulmonary artery wall is a characteristic feature of pulmonary hypertension (PH). In hypoxic PH, the most substantial pathologic changes occur in the adventitia. Here, there is marked fibroblast proliferation and profound macrophage accumulation. These PH fibroblasts (PH-Fibs) maintain a hyperproliferative, apoptotic-resistant, and proinflammatory phenotype in ex vivo culture. Considering that a similar phenotype is observed in cancer cells, where it has been associated, at least in part, with specific alterations in mitochondrial metabolism, we sought to define the state of mitochondrial metabolism in PH-Fibs. In PH-Fibs, pyruvate dehydrogenase was markedly inhibited, resulting in metabolism of pyruvate to lactate, thus consistent with a Warburg-like phenotype. In addition, mitochondrial bioenergetics were suppressed and mitochondrial fragmentation was increased in PH-Fibs. Most importantly, complex I activity was substantially decreased, which was associated with down-regulation of the accessory subunit nicotinamide adenine dinucleotide reduced dehydrogenase (ubiquinone) Fe-S protein 4 (NDUFS4). Owing to less-efficient ATP synthesis, mitochondria were hyperpolarized and mitochondrial superoxide production was increased. This pro-oxidative status was further augmented by simultaneous induction of cytosolic nicotinamide adenine dinucleotide phosphate reduced oxidase 4. Although acute and chronic exposure to hypoxia of adventitial fibroblasts from healthy control vessels induced increased glycolysis, it did not induce complex I deficiency as observed in PH-Fibs. This suggests that hypoxia alone is insufficient to induce NDUFS4 down-regulation and constitutive abnormalities in complex I. In conclusion, our study provides evidence that, in the pathogenesis of vascular remodeling in PH, alterations in fibroblast mitochondrial metabolism drive distinct changes in cellular behavior, which potentially occur independently of hypoxia.

• Keywords
• adventitial fibroblasts, complex I, mitochondria, oxidative metabolism, pulmonary hypertension,
• MeSH
• Cell Respiration MeSH
• Chronic Disease MeSH
• Citric Acid Cycle MeSH
• Down-Regulation MeSH
• Energy Metabolism MeSH
• Phenotype MeSH
• Fibroblasts metabolism   MeSH
• Glycolysis MeSH
• Hypoxia complications   pathology   MeSH
• Pyruvic Acid metabolism   MeSH
• Humans MeSH
• Macrophages metabolism   MeSH
• Mitochondria metabolism   MeSH
• Oxidation-Reduction MeSH
• Oxidative Phosphorylation MeSH
• Paracrine Communication MeSH
• Lung pathology   MeSH
• Hypertension, Pulmonary complications   metabolism   pathology   MeSH
• Cellular Reprogramming * MeSH
• Pyruvate Dehydrogenase Complex metabolism   MeSH
• Electron Transport Complex I metabolism   MeSH
• Cattle MeSH
• Superoxides metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Cattle MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Pyruvic Acid MeSH
• Pyruvate Dehydrogenase Complex MeSH
• Electron Transport Complex I MeSH
• Superoxides MeSH