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Published online before print March 29, 2006, 10.1183/09031936.06.00080105
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Eur Respir J 2006; 28:370-377
Copyright ©ERS Journals Ltd 2006

Allergic lung inflammation induces pulmonary vascular hyperresponsiveness

M. Witzenrath1, B. Ahrens2, S. M. Kube1, A. C. Hocke1, S. Rosseau1, E. Hamelmann2, N. Suttorp1 and H. Schütte1

1 Dept of Internal Medicine, Infectious Diseases and Respiratory Medicine, and 2 Dept of Paediatric Pneumology and Immunology, Charité, Universitätsmedizin Berlin, Berlin, Germany.

CORRESPONDENCE: M. Witzenrath, Dept of Internal Medicine, Infectious Diseases and Respiratory Medicine, Charité, Universitätsmedizin Berlin, Schumannstr 20/21, 10117 Berlin, Germany. Fax: 49 30450553979. E-mail: martin.witzenrath{at}charite.de

Keywords: Allergic inflammation, 5-hydroxytryptamine, isolated mouse lung, ovalbumin, pulmonary hypertension, serotonin

Received: July 8, 2005
Accepted March 19, 2006


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Pulmonary arterial vasoconstriction is an important early component of pulmonary hypertension. Inflammatory mechanisms play a prominent role in the pathogenesis of pulmonary hypertension. The present authors investigated the potential role of acute allergic lung inflammation for alterations in pulmonary haemodynamics.

BALB/c mice were intraperitoneally sensitised to ovalbumin and challenged by ovalbumin inhalation. Subsequently, lungs were ventilated and perfused ex vivo, and pulmonary arterial pressure (Ppa) was continuously monitored.

Isolated perfused lungs of allergen-sensitised and -challenged mice showed five-fold enhanced Ppa responses to serotonin, which is reported to be a significant contributor to pulmonary hypertension in humans. This increase in Ppa was abolished by the serotonin receptor-2A antagonist ketanserin, but not the serotonin receptor-1B antagonist GR127935. Intracellular signalling to serotonin involved phosphatidylcholine-specific phospholipase C and protein kinase C, as well as Rho-kinase, as assessed by employing the specific inhibitors D609, bisindolylmaleimide and Y27632, respectively. In addition to serotonin, impressively enhanced Ppa increases in allergic lungs were also evoked by the thromboxane receptor agonist U46619 [GenBank] , angiotensin II and endothelin-1.

In conclusion, allergic lung inflammation was accompanied by impressive pulmonary vascular hyperresponsiveness. These results suggest a possible role for allergic inflammation in the development of pulmonary arterial hypertension.

In inflammatory airway disorders, inflammation is not restricted to the airways, but may also affect pulmonary vessels. Examination of lungs from patients who died during an asthma attack revealed that inflammation, including eosinophilia, involves the tissue and large pulmonary arteries adjacent to bronchi 1. Moreover, in lungs from long-term smokers, morphological changes in pulmonary arteries in parallel with small airway disease and emphysema were found 2, and inflammatory mechanisms are assumed to contribute to alterations of the pulmonary circulation in chronic obstructive pulmonary disease (COPD) 3, 4. Against this background, it is noteworthy that a variety of autoimmune disorders and infectious diseases have been reported to be associated with pulmonary arterial hypertension (PAH) 5. Taken together, inflammatory mechanisms may, therefore, play an important role in the pathogenesis of PAH 5.

Structural and functional changes of the pulmonary circulation in PAH include remodeling of the pulmonary arterial wall, endothelial dysfunction and thrombosis 6, as well as pulmonary vasoconstriction, which is assumed to be an important early component of the hypertensive process 7. In this context, the vasoconstrictive agent serotonin (5-hydroxytryptamine; 5-HT) has been identified as a relevant contributor to PAH 7. Medication with the appetite suppressants aminorex fumarate and fenfluramine, resulting in elevated plasma 5-HT, was associated with an increased incidence of PAH 8, 9, but the predisposing factors that are essential for the manifestation of the disease are unknown 10.

In order to model pulmonary hypertension in rodents, intravascular monocrotaline application has been widely used, leading to neutrophilic pulmonary vascular inflammation, pulmonary hypertension and cor pulmonale 11. Perivascular immune responses with leukocyte infiltration were also observed in a variety of airway inflammation models 12. In particular, in a mouse model of allergic airway inflammation, extensive eosinophil and mononuclear cell infiltrates were seen around the pulmonary blood vessels 13, 14, and a recent study in mice showed that central features of allergen-induced airway remodeling were also present in the pulmonary vessels, including smooth muscle enlargement 15. These findings provide further evidence that, beyond airway alterations, allergic inflammation may also affect the pulmonary vascular bed. However, the functional consequences of these findings remain unknown.

In the current study, it was observed that allergen-induced lung inflammation induced increased pulmonary arterial pressor responses to 5-HT measured in isolated perfused mouse lungs. The present authors investigated the contribution of the 5-HT2A and 5-HT1B/D receptor, addressed the 5-HT specificity of the observed phenomenon, and analysed the intracellular signalling pathways related to the 5-HT induced pulmonary vascular responses.


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Allergen sensitisation and challenge
All experimental procedures were approved by local authorities. Pathogen-free female BALB/c mice (20–23 g; BgVV, Berlin, Germany) were maintained on an ovalbumin (OVA)-free diet. Systemic sensitisation with OVA (20 µg·injection-1; Sigma, Deisenhofen, Germany) adsorbed to 2 mg Al(OH)3 (Pierce, Rockford, IL, USA) by i.p. injections on days 0 and 14, and repeated airway challenges with aerosolised 1% OVA (weight/volume) in PBS (20 min) on days 28, 29 and 30 were performed as described 16 (fig. 1Go).


Figure 1
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  		Fig. 1— Diagram to show the animal treatment protocol. Mice were sensitised to ovalbumin (OVA) adsorbed to Al(OH)3, by i.p. injections or received vehicle on days 0 and 14. On indicated days, airway challenges were performed with 1% OVA or solvent (PBS), delivered by aerosolisation for 20 min. The airway response to methacholine was measured in vivo on day 31 by means of whole body plethysmography (WBP) determining "enhanced pause" (Penh). On day 32, ex vivo airway and vascular responses were determined in the isolated perfused and ventilated mouse lung (IPL).

 
Preparation of bronchoalveolar lavage fluid
Animals were killed 24 h after the last airway challenge, and the tracheas were cannulated. Airways underwent lavage twice with 1 mL of ice-cold PBS, and cell numbers were determined as previously described 17. Total leukocytes, lymphocytes, eosinophils and macrophages were differentiated in bronchoalveolar lavage fluid (BALF) according to morphological criteria 17.

Histochemistry
Lung tissue was fixed in 4% formalin, dehydrated, mounted in paraffin, sectioned and stained with periodic acid-Schiff (PAS) reaction using a standard protocol.

Serum levels of total and OVA-specific immunoglobulin E
On day 31, serum levels of total and OVA-specific immunoglobulin (Ig)E were measured by means of ELISA, as previously described 18. Levels of OVA-specific IgE were related to pooled standards generated in the authors’ laboratory and expressed as arbitrary units per mL. Total serum IgE (Sigma, Taufkirchen, Germany) levels were calculated by comparison with known mouse IgE standards and expressed in ng·mL-1.

In vivo airway responsiveness
Airway responsiveness (AR) was measured in unrestrained animals by barometric whole body plethysmography (Buxco®; EMKA Technologies, Paris, France) as described elsewhere 16. As an index of in vivo airway obstruction, enhanced pause (Penh) values were calculated 16.

Isolated perfused mouse lung
Mouse lungs were prepared as described previously 19, 20. Lungs were perfused with 37°C sterile Krebs-Henseleit-hydroxyethylamylopectine buffer (1 mL·min-1; Serag–Wiesner, Naila, Germany) in a nonrecirculating fashion, and left atrial pressure was adjusted at +2.2 cmH2O. Pulmonary arterial pressure (Ppa) and venous pressure were continuously monitored and digitised. Following isolation, lungs were ventilated by constant negative pressure (expiration: 4.5 cmH2O to inspiration -9.0 cmH2O; 90 breaths·min-1) in a closed chamber. Hyperinflation (-24 cmH2O) was performed at 4-min intervals. The chamber pressure was continuously measured by a differential pressure transducer, and airflow velocity was monitored by means of a pneumotachograph connected to a second differential pressure transducer. Signals were amplified and registered with Pulmodyn® software, and the data for airway resistance (Raw) were analysed as described previously 21. All hardware and software were purchased from HSE Harvard Apparatus, March-Hugstetten, Germany.

Airway and vascular responsiveness in isolated perfused mouse lung
After a steady state period of 30 min, 5-HT (Sigma, Taufkirchen, Germany) or, alternatively, the thromboxane receptor agonist U46619 [GenBank] , angiotensin II or endothelin-1 (all Calbiochem, Darmstadt, Germany) were administered to the perfusate for 30 s, 3, 2 or 10 min, respectively. The concentration of either agent was increased in 12-min intervals. Raw and Ppa were determined 30 s before and at the respective maximum response after 5-HT, U46619 [GenBank] , angiotensin II or endothelin-1 administration. The change in Raw was expressed as fold Raw, and the difference in Ppa ({Delta}Ppa) was expressed in cmH2O.

Ketanserin (1 µM; Sigma, Taufkirchen, Germany), GR127935 (0.1 µM; donated by GlaxoSmithKline, Munich, Germany), D609 (100 µM; Sigma), xestospongin C (1 µM; Biomol, Hamburg, Germany), bisindolylmaleimide (10 µM), or Y27632 (5 µM; both Calbiochem, Darmstadt, Germany) were administered to the perfusate 10 min prior to 5-HT application.

Data analysis
Data are expressed as mean±SEM. Differences were analysed by ANOVA, followed by post hoc Student–Newman–Keuls test.


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Allergen-induced lung inflammation
On day 31, allergen-induced lung inflammation was evaluated. The total number of cells, as well as the number of eosinophils and lymphocytes, was increased in BALF of OVA/OVA mice compared with all other groups (fig. 2aGo). Plasma levels of total IgE and OVA-specific IgE were increased in OVA-sensitised animals compared with PBS/PBS and PBS/OVA animals (fig. 2bGo). OVA/OVA mice showed increased in vivo AR, whereas OVA/PBS, PBS/OVA and PBS/PBS treated mice displayed low AR, as assessed by measuring Penh in unrestrained animals by barometric whole body plethysmography after inhalative challenges with increasing methacholine doses (data not given). PAS stained lung sections of OVA/OVA mice revealed peribronchial and perivascular infiltrates (fig. 2cGo).


Figure 2
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  		Fig. 2— Allergic lung inflammation following ovalbumin (OVA)-sensitisation and challenge. Animals were sensitised and challenged as described in figure 1Go. a) Bronchoalveolar lavage (BAL) was performed for cell count (n = 8–10). b) Day 31, blood was sampled for total immunoglobulin (Ig)E detection (n = 4–8) and c) ovalbumin (OVA)-specific IgE detection. d, e) Representative view of lung sections stained with haematoxylin-eosin and periodic acid-Schiff stain in PBS/PBS and OVA/OVA (d and e, respectively). {square}: total cells; blk12: eosinophils; blk14: lymphocytes. Values are given as mean±SEM. Error bars are missing when falling into symbols. *: p<0.05; ***: p<0.001 versus all other groups. #: p<0.001 versus PBS/OVA.

 
Airway and vascular responsiveness to 5-HT in isolated perfused mouse lung
On day 32 of the protocol, lungs were ventilated and perfused ex vivo. 5-HT infusion induced a large, rapid and dose-dependent Ppa increase in the lungs of OVA-sensitised and OVA-challenged mice, whereas lungs of all control groups displayed only minor Ppa changes (fig. 3aGo). Lungs of OVA/OVA mice responded immediately to 5-HT perfusion, with Ppa peaking after 1 min and reaching baseline values within <4 min (≤10-5 M 5-HT) or within 10–20 min (10-4 M 5-HT). Importantly, in the isolated lungs, neither baseline Ppa values (OVA/OVA 8.83±0.23 cmH2O; OVA/PBS 9.28±0.31 cmH2O; PBS/OVA 7.98±0.50 cmH2O; PBS/PBS 8.79±0.37 cmH2O), nor baseline values for airway resistance (OVA/OVA 1.50±0.06 cmH2O·s-1·mL-1; OVA/PBS 1.52±0.08 cmH2O·s·mL-1; PBS/OVA 1.68±0.06 cmH2O·s·mL-1; PBS/PBS 1.55±0.08 cmH2O·s·mL-1) differed between the experimental groups. Isolated lungs of allergen-sensitised and -challenged mice showed enhanced AR to 5-HT as compared with all other experimental groups (fig. 3bGo).


Figure 3
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  		Fig. 3— Increase of pulmonary arterial pressure (Ppa) and airway resistance (Raw) in response to 5-hydroxytryptamine (5-HT) in isolated mouse lungs. Mice were sensitised and challenged as described in figure 1Go. Perfusion of the isolated lung was repetitively changed to buffer 5-HT (30 s each dose). Ppa (a) and Raw (b) were determined considering values 30 s before 5-HT perfusion and at maximum Ppa and Raw, respectively. {blacksquare}: ovalbumin (OVA)/OVA; •: PBS/PBS; {blacktriangleup}: OVA/PBS; {blacktriangledown}: PBS/OVA. Values are given as mean±SEM (n = 6 each). Error bars are missing when falling into symbols. *: p<0.05; **: p<0.01; ***: p<0.001 versus all other groups.

 
5-HT induced vasoconstriction is mediated via the 5-HT2A receptor
The current authors then analysed whether 5-HT contributed to the development of acute pulmonary vasoconstriction via the Gi-coupled 5-HT1 receptor or via the Gq-coupled 5-HT2A receptor. The specific 5-HT2A receptor antagonist ketanserin reduced the 5-HT-induced Ppa responses by >95%. In contrast, the 5-HT1-specific receptor antagonist GR127935 22 did not affect the pressor response to 5-HT, neither in lungs from OVA-sensitised and -challenged mice nor in lungs from nonsensitised, nonchallenged controls (fig. 4Go).


Figure 4
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  		Fig. 4— Increase of pulmonary arterial pressure (Ppa) in response to 5-hydroxytryptamine (5-HT) perfusion in presence or absence of the 5-HT1B receptor antagonist GR127935 (0.1 µM), or the 5-HT2A receptor antagonist ketanserin (1 µM). Mice were sensitised and challenged according to the protocol depicted in figure 1Go. Inhibitors were infused starting 10 min prior to perfusion with 5-HT (100 µM). Difference in Ppa ({Delta}Ppa) was determined considering values 30 s before 5-HT perfusion and at maximum Ppa. {square}: PBS/PBS; blk12: ovalbumin (OVA)/OVA. Data are presented as mean±SEM (n = 4 each). #: p<0.001 versus 5-HT- and 5-HT/GR127935-exposed OVA/OVA lungs; ***: p<0.001 versus 5-HT- and 5-HT/GR127935-exposed PBS/PBS lungs.

 
Vascular hyperresponsiveness in isolated perfused mouse lungs is not 5-HT specific
Similarly to 5-HT, the vasoconstrictors thromboxane A2, angiotensin II and endothelin-1 act via Gq-coupled receptors. When lungs were perfused with the thromboxane receptor agonist U46619 [GenBank] (3x10-9 to 3x10-8 M), Ppa in OVA/OVA lungs increased manifold as compared with all other groups (fig. 5aGo). Interestingly, AR to U46619 [GenBank] in OVA/OVA lungs was not different from all other groups (fig. 5bGo). Furthermore, in response to angiotensin II and endothelin-1, Ppa in OVA/OVA lungs showed higher increases compared with PBS/PBS lungs (fig. 5cGo and d).


Figure 5
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  		Fig. 5— Increase of pulmonary arterial pressure (Ppa) in isolated mouse lungs in response to a) U46619 c) angiotensin II, d) endothelin-1, and b) airway resistance (Raw) in response to U46619. Mice were sensitised and challenged as described in figure 1Go. Perfusion of the isolated lung was repetitively changed to buffer containing U46619 (3 min each dose), angiotensin II (2 min) or endothelin-1 (10 min). Difference in Ppa ({Delta}Ppa; a, c, d) and Raw (b) was determined considering values 30 s before perfusion with any agent and at maximum Ppa and Raw, respectively. {blacksquare}: ovalbumin (OVA)/OVA; {blacktriangleup}: OVA/PBS; {blacktriangledown}: PBS/OVA; •: PBS/PBS. Data are presented as mean±SEM (n = 4–5 each). Error bars are missing when falling into symbols. *: p<0.05; **: p<0.01; ***: p<0.001 versus all other groups.

 
Pressor response to 5-HT in OVA/OVA lungs mediated via phosphatidylcholine-specific phospholipase C and protein kinase C
Finally, the intracellular cascade involved in the signalling downstream of 5-HT was investigated. Pre-treatment of perfused OVA/OVA lungs with the phosphatidylcholine-specific phospholipase C (PC-PLC) inhibitor D609 largely attenuated the pressor responses to 5-HT (fig. 6Go). As D609 additionally inhibits sphingomyelin synthase 23, the current authors excluded a major importance of sphingomyelin synthesis for the pressor response by using the sphingomyelinase inactivator imipramine 24. Imipramine did not significantly reduce the Ppa increase to 5-HT (5-HT: 46.5±10.83 cmH2O; 5-HT+imipramine: 36.81±11.57 cmH2O; p = 0.69), suggesting that the pressor response depended on PC-PLC rather than sphingomyelin. Inhibition of a downstream effector of PC-PLC, inositol-1,4,5-triphosphate (IP3), using the IP3 receptor antagonist xestospongin C did not affect the 5-HT induced vasoconstriction. In contrast, pre-treatment with the selective protein kinase C (PKC) inhibitor bisindolylmaleimide almost completely abolished 5-HT-induced vasoconstriction in lungs from sensitised and challenged mice. Furthermore, blockade of the Rho-kinase pathway by the highly selective Rho-kinase inhibitor Y-27632 resulted in a distinct reduction of the Ppa increase (fig. 6Go).


Figure 6
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  		Fig. 6— Increase of pulmonary arterial pressure (Ppa) in response to 5-hydroxytryptamine (5-HT) in presence (blk12) or absence ({square}) of specific inhibitors for phosphatidylcholine-specific phospholipase C (D609; 10 µM), protein kinase C (bisindolylmaleimide (BIM); 10 µM), the inositol triphosphate receptor antagonist xestospongin C (xesto; 1 µM), or the Rho-kinase (Y27632; 5 µM). Mice were sensitised and challenged according to the protocol depicted in figure 1Go. Inhibitors were infused starting 10 min prior to perfusion with 5-HT (100 µM). Difference in Ppa ({Delta}Ppa) was determined considering values 30 s before 5-HT perfusion and at maximum Ppa. Data are presented as mean±SEM (n = 4 each). **: p<0.01 versus control; ***: p<0.001 versus control.

 

   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The main findings of the current study were as follows. 1) Allergic lung inflammation induced by allergen-sensitisation and -challenge caused impressive pulmonary vascular hyperresponsiveness to 5-HT in mice. 2) The increased vascular response to 5-HT was mediated by the Gq-coupled 5-HT2A receptor. 3) Allergen-induced pulmonary vascular hyperresponsiveness was not specific to 5-HT. 4) The intracellular signalling process in response to 5-HT involved PC-PLC and PKC, as well as Rho-kinase.

At present, the relevance of these findings for human disease remains unknown and it is not clear if allergen-induced pulmonary vascular hyperresponsiveness parallels airway hyperresponsiveness (a cardinal feature of asthma 25) in humans.

However, pulmonary arterial vasoconstriction is regarded as an important early step in pulmonary hypertension (PH) pathogenesis 7. PH can be associated with diverse inflammatory diseases, including infections (HIV 26, human herpes virus 8 27, schistosomiasis 28) and autoimmune disorders (e.g. lupus erythematosus 29, scleroderma 30), as well as COPD, suggesting a role for inflammatory mechanisms in PH 7. In COPD, airway inflammation is assumed to affect the entire lung including the pulmonary vasculature 4, which might be relevant for PH pathogenesis. Moreover, in exacerbations of COPD triggered by respiratory infections, deterioration of cor pulmonale frequently occurs 3, 31.

There is only very little information concerning a link between allergic lung inflammation and pulmonary vascular responses, and the current study did not identify the exact mechanism. Due to the close vicinity of the pulmonary vessels and the airways, it is tempting to speculate that overspill of inflammatory mediators 32 may contribute to vascular hyperresponsiveness. Notably, a recent study demonstrated that the alterations in the protein expression profile after allergen sensitisation and challenge partly correlated with those observed in hypoxia 33, which is known to induce PAH and increased vascular responses to vasoconstrictors 34, 35.

In a variety of airway inflammation models, perivascular immune responses were observed 12, and important features of airway remodeling were noted in the pulmonary vessels of allergen-sensitised and -challenged mice 15. In order to investigate the impact of acute allergic lung inflammation on the pulmonary circulation, the current authors employed a well established murine model of acute allergen-sensitisation and challenge, which is characterised by several important features of allergic airway inflammation, including AR, eosinophil infiltration of the airways, and production of allergen-specific IgE 16, 36. Histology showed peribronchial and perivascular leukocyte infiltrations, thus suggesting acute inflammation in the pulmonary vascular bed. Chronic allergen exposure, however, may have different biological impact on the pulmonary circulation, but was beyond the scope of the current study.

5-HT appears to be involved in the pathogenesis of PAH 7. In the current model, 5-HT caused an immediate, dramatic Ppa increase in lungs of allergen-sensitised and -challenged mice in addition to enhanced bronchoconstriction. In control lungs, 5-HT evoked only a moderate vascular pressor response, which is in line with previous studies 21. Acute vasoconstriction to 5-HT was mediated by the 5-HT1B receptor in human pulmonary arteries ex vivo 37 and in vivo 38, whereas in normal rat pulmonary arteries, these responses were mediated predominantly by the 5-HT2A receptor 39. In ex vivo perfused lungs of allergen-sensitised and -challenged mice, as well as control mice, the 5-HT-evoked Ppa responses were blocked by the 5-HT2A receptor antagonist ketanserin, whereas 5-HT1B receptor antagonism by GR127935 did not diminish vasoconstriction. Moreover, the 5-HT1B/D receptor agonist sumatriptan (1–100 µM) did not affect Ppa (data not given in detail). These results suggest an exclusive role of the 5-HT2A receptor, without the modulatory function of the 5-HT1B receptor described in chronic hypoxic rats 39 and mice 34, where 5-HT2A (Gq-coupled) and 5-HT1B (Gi-coupled) receptors were assumed to act synergistically 40.

In addition to 5-HT, thromboxane, endothelin-1 and angiotensin II, which also bind to G-protein coupled receptors in the pulmonary vasculature 40, have all been reported to cause acute pulmonary arterial vasoconstriction 21, 41, 42. In the present study, low doses of the thromboxane receptor agonist U46619 [GenBank] caused an impressive Ppa response in lungs of allergen-sensitised and -challenged mice. As the employed doses were lower than reported to cause bronchial constriction in previous studies 21, airway resistance was only marginally affected by U46619. [GenBank] Therefore, a possible contribution of mechanical interaction between airway pressure and Ppa to the Ppa increase was excluded.

Furthermore, perfusion with endothelin-1 or angiotensin II also resulted in a pronounced arterial pressor response in OVA/OVA, as compared with PBS/PBS-lungs. Although these vasoconstrictors may not exclusively act via Gq-coupled receptors, the current results suggest an important role of this pathway.

Gq-coupled receptors activate PLC, thereby increasing cytosolic IP3 43 and diacylglycerol (DAG). IP3 induces cytosolic Ca2+ increase, followed by myosin light chain (MLC) phosphorylation and subsequent smooth muscle contraction 43. DAG activates PKC, leading to increased MLC phosphorylation via diverse mechanisms 43, 44. By using specific inhibitors, the current authors demonstrated that the enhanced Ppa response to 5-HT in allergen-sensitised and -challenged murine lungs was PC-PLC and PKC dependent. In contrast, the IP3-receptor antagonist xestospongin C did not influence the 5-HT-induced pressor response, although the employed concentration was three-fold above 50% of the median inhibitory concentration 45. However, at this concentration xestospongin prevented acetylcholine-induced calcium-signalling in lung slices 46 and attenuated platelet activating factor-induced oedema formation in isolated lungs 47.

Beyond IP3 and PKC, activated Rho-kinase indirectly increases MLC phosphorylation contributing to additional contractile force of myofilaments without changes in Ca2+ concentration 48. Pre-treatment with the highly selective Rho-kinase inhibitor Y27632 49 reduced the enhanced pressor response significantly. Interestingly, augmented contribution of Rho-kinase to airway smooth muscle contraction in allergen-sensitised guinea pigs has recently been described 50. Moreover, Rho-kinase was upregulated in carotid arteries of spontaneously hypertensive rats 51 and in coronary arteries of interleukin-1ß-treated pigs 52, leading to vascular hyperresponsiveness to 5-HT. Against this background, a role for the Ca2+ sensitising Rho-kinase pathway in allergen-induced pulmonary vascular hyperresponsiveness may be assumed.

Concerning the role of 5-HT in human airways, several issues remain unsettled. Interestingly, in addition to being implicated in PH pathogenesis, serum 5-HT levels were associated with clinical severity and pulmonary function in human asthma, and were increased in asthma attacks 53. However, a contribution of elevated serum 5-HT to PH and right heart failure in acute severe human asthma is currently not known.

In conclusion, the present authors have shown that allergen sensitisation and inhalative challenge of mice, which is well established to induce allergic lung inflammation and airway hyperresponsiveness, results in distinct vascular hyperresponsiveness to different vasoconstrictive agonists. These results suggest that allergic inflammation of the lung may play a role in the pathobiology of pulmonary hypertension.


   REFERENCES
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Saetta M, Di Stefano A, Rosina C, Thiene G, Fabbri LM. Quantitative structural analysis of peripheral airways and arteries in sudden fatal asthma. Am Rev Respir Dis 1991;143:138–143.[ISI][Medline] [Order article via Infotrieve]
  2. Hale KA, Niewoehner DE, Cosio MG. Morphologic changes in the muscular pulmonary arteries: relationship to cigarette smoking, airway disease, and emphysema. Am Rev Respir Dis 1980;122:273–278.[ISI][Medline] [Order article via Infotrieve]
  3. Barbera JA, Peinado VI, Santos S. Pulmonary hypertension in chronic obstructive pulmonary disease. Eur Respir J 2003;21:892–905.[Abstract/Free Full Text]
  4. Voelkel NF, Cool CD. Pulmonary vascular involvement in chronic obstructive pulmonary disease. Eur Respir J 2003;22: Suppl. 46 28s–32s.[CrossRef][ISI]
  5. Dorfmuller P, Perros F, Balabanian K, Humbert M. Inflammation in pulmonary arterial hypertension. Eur Respir J 2003;22:358–363.[Abstract/Free Full Text]
  6. Rubin LJ. Primary pulmonary hypertension. N Engl J Med 1997;336:111–117.[Free Full Text]
  7. Humbert M, Morrell NW, Archer SL, et al. Cellular and molecular pathobiology of pulmonary arterial hypertension. J Am Coll Cardiol 2004;43: Suppl. 12 13S–24S.[Abstract/Free Full Text]
  8. Greiser E. Epidemiologic studies on the relation between use of appetite depressants and primary vascular pulmonary hypertension. Internist (Berl) 1973;14:437–442.[Medline] [Order article via Infotrieve]
  9. Mark EJ, Patalas ED, Chang HT, Evans RJ, Kessler SC. Fatal pulmonary hypertension associated with short-term use of fenfluramine and phentermine. N Engl J Med 1997;337:602–606.[Free Full Text]
  10. Michelakis ED, Weir EK. Anorectic drugs and pulmonary hypertension from the bedside to the bench. Am J Med Sci 2001;321:292–299.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  11. Wilson DW, Segall HJ, Pan LC, Lame MW, Estep JE, Morin D. Mechanisms and pathology of monocrotaline pulmonary toxicity. Crit Rev Toxicol 1992;22:307–325.[ISI][Medline] [Order article via Infotrieve]
  12. Pabst R, Tschernig T. Perivascular capillaries in the lung: an important but neglected vascular bed in immune reactions? J Allergy Clin Immunol 2002;110:209–214.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  13. Henderson WR Jr, Tang LO, Chu SJ, et al. A role for cysteinyl leukotrienes in airway remodeling in a mouse asthma model. Am J Respir Crit Care Med 2002;165:108–116.[Abstract/Free Full Text]
  14. Singh B, Shinagawa K, Taube C, Gelfand EW, Pabst R. Strain-specific differences in perivascular inflammation in lungs in two murine models of allergic airway inflammation. Clin Exp Immunol 2005;141:223–229.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  15. Tormanen KR, Uller L, Persson CG, Erjefalt JS. Allergen Exposure of Mouse Airways Evokes Remodeling of both Bronchi and Large Pulmonary Vessels. Am J Respir Crit Care Med 2005;171:19–25.[Abstract/Free Full Text]
  16. Hamelmann E, Schwarze J, Takeda K, et al. Noninvasive measurement of airway responsiveness in allergic mice using barometric plethysmography. Am J Respir Crit Care Med 1997;156:766–775.[Abstract/Free Full Text]
  17. Hamelmann E, Takeda K, Schwarze J, Vella AT, Irvin CG, Gelfand EW. Development of eosinophilic airway inflammation and airway hyperresponsiveness requires interleukin-5 but not immunoglobulin E or B lymphocytes. Am J Respir Cell Mol Biol 1999;21:480–489.[Abstract/Free Full Text]
  18. Hamelmann E, Oshiba A, Loader J, et al. Antiinterleukin-5 antibody prevents airway hyperresponsiveness in a murine model of airway sensitization. Am J Respir Crit Care Med 1997;155:819–825.[Abstract]
  19. von Bethmann AN, Brasch F, Nusing R, et al. Hyperventilation induces release of cytokines from perfused mouse lung. Am J Respir Crit Care Med 1998;157:263–272.[ISI][Medline] [Order article via Infotrieve]
  20. Seybold J, Thomas D, Witzenrath M, et al. Tumor necrosis factor-alpha-dependent expression of phosphodiesterase 2: role in endothelial hyperpermeability. Blood 2005;105:3569–3576.[Abstract/Free Full Text]
  21. Held HD, Martin C, Uhlig S. Characterization of airway and vascular responses in murine lungs. Br J Pharmacol 1999;126:1191–1199.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  22. Skingle M, Beattie DT, Scopes DI, et al. GR127935: a potent and selective 5-HT1D receptor antagonist. Behav Brain Res 1996;73:157–161.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  23. Luberto C, Hannun YA. Sphingomyelin synthase, a potential regulator of intracellular levels of ceramide and diacylglycerol during SV40 transformation. Does sphingomyelin synthase account for the putative phosphatidylcholine-specific phospholipase C? J Biol Chem 1998;273:14550–14559.[Abstract/Free Full Text]
  24. Hurwitz R, Ferlinz K, Sandhoff K. The tricyclic antidepressant desipramine causes proteolytic degradation of lysosomal sphingomyelinase in human fibroblasts. Biol Chem Hoppe Seyler 1994;375:447–450.[ISI][Medline] [Order article via Infotrieve]
  25. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention. NIH Publication No 02-3659. Bethesda, National Heart, Lung and Blood Institute and GINA Executive Committee, 2004
  26. Petitpretz P, Brenot F, Azarian R, et al. Pulmonary hypertension in patients with human immunodeficiency virus infection. Comparison with primary pulmonary hypertension. Circulation 1994;89:2722–2727.[Abstract/Free Full Text]
  27. Cool CD, Rai PR, Yeager ME, et al. Expression of human herpes virus 8 in primary pulmonary hypertension. N Engl J Med 2003;349:1113–1122.[Abstract/Free Full Text]
  28. Bethlem EP, Schettino GP, Carvalho CR. Pulmonary schistosomiasis. Curr Opin Pulm Med 1997;3:361–365.[Medline] [Order article via Infotrieve]
  29. Carreira PE. Pulmonary hypertension in autoimmune rheumatic diseases. Autoimmun Rev 2004;3:313–320.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  30. Cool CD, Kennedy D, Voelkel NF, Tuder RM. Pathogenesis and evolution of plexiform lesions in pulmonary hypertension associated with scleroderma and human immunodeficiency virus infection. Hum Pathol 1997;28:434–442.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  31. Weitzenblum E, Apprill M, Oswald M, Chaouat A, Imbs JL. Pulmonary hemodynamics in patients with chronic obstructive pulmonary disease before and during an episode of peripheral edema. Chest 1994;105:1377–1382.[Medline] [Order article via Infotrieve]
  32. Fernandes DJ, Mitchell RW, Lakser O, Dowell M, Stewart AG, Solway J. Do inflammatory mediators influence the contribution of airway smooth muscle contraction to airway hyperresponsiveness in asthma? J Appl Physiol 2003;95:844–853.[Abstract/Free Full Text]
  33. Fajardo I, Svensson L, Bucht A, Pejler G. Increased levels of hypoxia-sensitive proteins in allergic airway inflammation. Am J Respir Crit Care Med 2004;170:477–484.[Abstract/Free Full Text]
  34. Keegan A, Morecroft I, Smillie D, Hicks MN, MacLean MR. Contribution of the 5-HT(1B) receptor to hypoxia-induced pulmonary hypertension: converging evidence using 5-HT(1B)-receptor knockout mice and the 5-HT(1B/1D)-receptor antagonist GR127935. Circ Res 2001;89:1231–1239.[Abstract/Free Full Text]
  35. Bonnet S, Belus A, Hyvelin JM, Roux E, Marthan R, Savineau JP. Effect of chronic hypoxia on agonist-induced tone and calcium signaling in rat pulmonary artery. Am J Physiol Lung Cell Mol Physiol 2001;281:L193–L201.[Abstract/Free Full Text]
  36. Hamelmann E, Cieslewicz G, Schwarze J, et al. Anti-interleukin 5 but not anti-IgE prevents airway inflammation and airway hyperresponsiveness. Am J Respir Crit Care Med 1999;160:934–941.[Abstract/Free Full Text]
  37. Morecroft I, Heeley RP, Prentice HM, Kirk A, MacLean MR. 5-hydroxytryptamine receptors mediating contraction in human small muscular pulmonary arteries: importance of the 5-HT1B receptor. Br J Pharmacol 1999;128:730–734.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  38. Hood S, Birnie D, Hillis S. The haemodynamic effects of subcutaneous sumatriptan, a 5HT1-receptor agonist. Br J Clin Pharmacol 1997;43:327–328.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  39. MacLean MR, Sweeney G, Baird M, McCulloch KM, Houslay M, Morecroft I. 5-Hydroxytryptamine receptors mediating vasoconstriction in pulmonary arteries from control and pulmonary hypertensive rats. Br J Pharmacol 1996;119:917–930.[ISI][Medline] [Order article via Infotrieve]
  40. MacLean MR. Pulmonary hypertension, anorexigens and 5-HT: pharmacological synergism in action? Trends Pharmacol Sci 1999;20:490–495.[CrossRef][Medline] [Order article via Infotrieve]
  41. Held HD, Uhlig S. Basal lung mechanics and airway and pulmonary vascular responsiveness in different inbred mouse strains. J Appl Physiol 2000;88:2192–2198.[Abstract/Free Full Text]
  42. Cargill RI, Lipworth BJ. The role of the renin-angiotensin and natriuretic peptide systems in the pulmonary vasculature. Br J Clin Pharmacol 1995;40:11–18.[ISI][Medline] [Order article via Infotrieve]
  43. Harnett KM, Biancani P. Calcium-dependent and calcium-independent contractions in smooth muscles. Am J Med 2003; 115: Suppl. 3A, 24S–30S
  44. Morgan KG, Leinweber BD. PKC-dependent signalling mechanisms in differentiated smooth muscle. Acta Physiol Scand 1998;164:495–505.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  45. Gafni J, Munsch JA, Lam TH, et al. Xestospongins: potent membrane permeable blockers of the inositol 1,4,5-trisphosphate receptor. Neuron 1997;19:723–733.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  46. Bergner A, Sanderson MJ. ATP stimulates Ca2+ oscillations and contraction in airway smooth muscle cells of mouse lung slices. Am J Physiol Lung Cell Mol Physiol 2002;283:L1271–L1279.[Abstract/Free Full Text]
  47. Göggel R, Uhlig S. PAF-induced edema is mediated partly by activation of the inositol trisphosphate (IP3)-receptor. Am J Respir Crit Care Med 2000;161:A418
  48. Somlyo AP, Somlyo AV. Signal transduction and regulation in smooth muscle. Nature 1994;372:231–236.[CrossRef][Medline] [Order article via Infotrieve]
  49. Uehata M, Ishizaki T, Satoh H, et al. Calcium sensitization of smooth muscle mediated by a Rho-associated protein kinase in hypertension. Nature 1997;389:990–994.[CrossRef][Medline] [Order article via Infotrieve]
  50. Schaafsma D, Gosens R, Bos IS, Meurs H, Zaagsma J, Nelemans SA. Allergic sensitization enhances the contribution of Rho-kinase to airway smooth muscle contraction. Br J Pharmacol 2004;143:477–484.[CrossRef][ISI][Medline] [Order article via Infotrieve]
  51. Mukai Y, Shimokawa H, Matoba T, et al. Involvement of Rho-kinase in hypertensive vascular disease: a novel therapeutic target in hypertension. FASEB J 2001;15:1062–1064.[Free Full Text]
  52. Kandabashi T, Shimokawa H, Miyata K, et al. Inhibition of myosin phosphatase by upregulated rho-kinase plays a key role for coronary artery spasm in a porcine model with interleukin-1beta. Circulation 2000;101:1319–1323.[Abstract/Free Full Text]
  53. Lechin F, van der DB, Orozco B, Lechin M, Lechin AE. Increased levels of free serotonin in plasma of symptomatic asthmatic patients. Ann Allergy Asthma Immunol 1996;77:245–253.[ISI][Medline] [Order article via Infotrieve]



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