AIMS: To elucidate the role of alveolar macrophages (AM) in the pathogenesis of hypoxic pulmonary hypertension (HPH), we tested the effects of sustained hypoxia on AM polarization and on the formation of superoxide by AM in vivo and in vitro. MAIN METHODS: Rat AM were obtained by bronchoalveolar lavage. 4-day exposure to hypoxia (10% O2) was carried out in vivo (rats in isobaric hypoxic chamber, controls kept in air) or in vitro (control AM in 21% O2 and 5% CO2). Superoxide production was measured by luminol-orthovanadate chemiluminescence, AM polarization was detected immunocytochemically. To ascertain the effect of substances contained in the alveolar environment, we cultivated cells also in the presence of non-cellular components of the bronchoalveolar lavage fluid (BALF) either from controls or from rats exposed to 4 days of hypoxia. KEY FINDINGS: In vivo, but not in vitro, hypoxia increased AM superoxide production. Both types of hypoxia polarized AM into M2 (pro-proliferative) type. While the presence of control BALF attenuated superoxide production in AM cultivated in normoxia, BALF from the hypoxia-exposed rats had no effect. In AM cultivated in hypoxia, superoxide production was not altered by control BALF and elevated by BALF obtained from hypoxic rats. SIGNIFICANCE: Hypoxia does not influence superoxide production by AM directly but rather by modulating their milieu and their sensitivity to external influences.
- MeSH
- alveolární makrofágy metabolismus patologie MeSH
- bronchoalveolární lavážní tekutina chemie MeSH
- hypoxie patofyziologie MeSH
- krysa rodu rattus MeSH
- kultivované buňky MeSH
- potkani Wistar MeSH
- superoxidy metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Exposure to hypoxia, leading to hypoxic pulmonary hypertension (HPH), is associated with activation of alveolar macrophages (AM). However, it remains unclear how AM participate in this process. There are studies which imply that the AM product monocyte chemoattractant protein-1 (MCP-1) plays an important role. Thus we tested: 1. if the selective elimination of AM attenuates HPH in rats, 2. the correlation of MCP-1 plasmatic concentrations with the presence and absence of AM during exposure to hypoxia, 3. the direct influence of hypoxia on MCP-1 production in isolated AM. We found that experimental depletion of AM attenuated the chronic hypoxia-induced increase in mean pulmonary arterial pressure, but did not affect the serum MCP-1 concentrations. Furthermore, the MCP-1 production by AM in vitro was unaffected by hypoxia. Thus we conclude that AM play a significant role in the mechanism of HPH, but MCP-1 release from these cells is most likely not involved in this process. The increase of MCP-1 accompanying the development of HPH probably originates from other sources than AM.
- MeSH
- alveolární makrofágy sekrece MeSH
- chemokin CCL2 krev MeSH
- dichlormethylendifosfonát terapeutické užití MeSH
- hypoxie komplikace MeSH
- plicní hypertenze imunologie prevence a kontrola MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
To test whether macrophages can play any role in hypoxic pulmonary vasoconstriction, we tested the in vitro response of rings from small pulmonary arteries to the activation of macrophages by FMLP, a substance stimulating predominantly membrane-bound NADPH oxidase. A small vessel myograph was used to measure the responses of rings from small pulmonary arteries (300-400 microm) isolated from rat lungs. Rings from 5 rats were placed into both chambers of the myograph. The vessels were stabilized for 40 min and then normalized by automatic stretching to a wall tension equivalent to the intravascular pressure 30 mm Hg. At the start of each experiment, vessels were exposed to 80 mM K+ to obtain maximal contractile response, which was used to normalize subsequent contractile responses. 2x10(6) viable macrophages, obtained by peritoneal lavage, were added into one chamber, then 5 microM FMLP was administrated to both chambers and the tension measurement was started. The hydrogen peroxide concentration produced by stimulated macrophages was measured luminometrically. The concentrations of H2O2 in specimens from chambers containing activated macrophages rose from 3.5+/-1.5 nM to 110+/-28 nM within 25 min of stimulation, while FMLP itself didn't increase the H2O2 concentration from the baseline value (4.5+/-3 nM) in samples from control chambers. After FMLP administration, the tension of the vessel rings in the presence of macrophages reached 0.23+/-0.07 of maximal contractile response, it did not change in controls. The addition of ROS scavenger 4-hydroxy-TEMPO blocked the contractile response to the activation of macrophages. We conclude that the activation of macrophages stimulates the contraction of small pulmonary arteries and that this contraction is probably mediated by reactive oxygen species.
- MeSH
- arteria pulmonalis metabolismus MeSH
- krysa rodu rattus MeSH
- orgánové kultury - kultivační techniky MeSH
- peritoneální makrofágy metabolismus MeSH
- potkani Wistar MeSH
- reaktivní formy kyslíku metabolismus MeSH
- vazokonstrikce fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Chronic hypoxia causes oxidative injury of pulmonary vessels and attenuates their reactivity to different stimuli. When combined with hypercapnia, biochemical markers of this injury are reduced but the effect of concomitant hypoxia and hypercapnia on vascular reactivity is not fully understood. This study was therefore designed to test whether hypercapnia can prevent also the hypoxia-induced loss of reactivity of pulmonary vessels. The reactivity of vessels from rats exposed either to hypoxia or hypoxia combined with hypercapnia was tested using a small vessel myograph (M 500A, Linton, Norfolk, GB). The second and third intrapulmonary branches of pulmonary arteries were isolated under a dissecting microscope from lungs of 8 control rats (group N), 6 rats exposed to hypoxia for 5 days (isobaric, 10 % O(2), group H) and 7 rats exposed to hypoxia combined with hypercapnia for 5 days (10 % O(2), 5 % CO(2), group H+CO(2)). The transmural pressure was set by automatic normalization to 30 mm Hg. The vessel size did not vary among the groups. After stabilization we challenged the vessels twice with KCl (80 mM) and once with PGF(2alpha) (0.1 mM). There were no significant differences in KCl induced contractions among the groups. The responses to PGF(2alpha) were expressed as a ratio to the maximal tension obtained by the exposure to 80 mM KCl. Contractions induced by PGF(2alpha) were markedly reduced in group H (0.07+/-0.02) and in group H+CO(2) (0.26+/-0.03) in comparison with group N (0.83+/-0.07). The vessels of group H responded to PGF(2alpha) less than those of group H+CO(2). However we observed the attenuated reactivity also in group H+CO(2) in comparison with N. Hypercapnia therefore partially blunted the hypoxia-induced loss of reactivity in pulmonary arteries. This finding supports the hypothesis that hypercapnia significantly alters the nature of lung injury induced by chronic hypoxia.
- MeSH
- arteria pulmonalis účinky léků patofyziologie MeSH
- časové faktory MeSH
- chronická nemoc MeSH
- hyperkapnie patofyziologie MeSH
- hypoxie patofyziologie MeSH
- krysa rodu rattus MeSH
- modely nemocí na zvířatech MeSH
- potkani Wistar MeSH
- vazokonstrikce * účinky léků MeSH
- vazokonstriktory farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Pulmonary hypertension resulting from chronic hypoxia is at least partly caused by the increased production of reactive oxygen species (ROS). The goal of the presented study was to investigate the dynamics and the site of production of ROS during chronic hypoxia. In our study Wistar rats were kept for 1, 4 and 21 days in an isobaric hypoxic chamber (FiO2=0.1), while controls stayed in normoxia. We compared NO production in expired air, plasma and perfusate drained from isolated rat lungs and measured superoxide concentration in the perfusate. We also detected the presence of superoxide products (hydrogen peroxide and peroxynitrite) and the level of ROS-induced damage expressed as the concentration of lipid peroxydation end products. We found that the production and release of ROS and NO during early phase of chronic hypoxia has specific timing and differs in various compartments, suggesting the crucial role of ROS interaction for development of hypoxic pulmonary hypertension.
- MeSH
- arteria pulmonalis metabolismus MeSH
- hypoxie komplikace metabolismus MeSH
- krysa rodu rattus MeSH
- kyselina peroxydusitá metabolismus MeSH
- oxid dusnatý biosyntéza krev MeSH
- peroxid vodíku metabolismus MeSH
- plicní hypertenze etiologie MeSH
- potkani Wistar MeSH
- reaktivní formy kyslíku metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
Hypoxic pulmonary hypertension (HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries. Mast cells have an important role in many inflammatory diseases and they are also involved in tissue remodeling. Tissue hypoxia is associated with mast cell activation and the release of proteolytic enzymes, angiogenic and growth factors which mediate tissue destruction and remodeling in a variety of physiological and pathological conditions. Here we focused on the role of mast cells in the pathogenesis of hypoxic pulmonary hypertension from the past to the present.
- MeSH
- hypoxie buňky MeSH
- lidé MeSH
- mastocyty metabolismus MeSH
- plicní hypertenze metabolismus patologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
