[Diagnostic Algorithm and Screening of Pulmonary Hypertension]. / Diagnose Algorithmus der pulmonalen Hypertonie und Screening-Verfahren.

The new guidelines for the diagnosis and treatment of pulmonary hypertension include a new diagnostic algorithm and provide specific recommendations for the required diagnostic procedures, including screening methods. These recommendations are commented on by national experts under the auspices of the DACH. These comments provide additional decision support and background information, serving as a further guide for the complex diagnosis of pulmonary hypertension.

Impairment of Inspiratory Muscle Function after COVID-19.

BACKGROUND: Persistent symptoms after acute coronavirus-disease-2019 (COVID-19) are common, and there is no significant correlation with the severity of the acute disease. In long-COVID (persistent symptoms >4 weeks after acute COVID-19), respiratory symptoms are frequent, but lung function testing shows only mild changes that do not explain the symptoms. Although COVID-19 may lead to an impairment of the peripheral nervous system and skeletal muscles, respiratory muscle function has not been examined in this setting. METHODS: In this study, we assessed the severity of dyspnea (NYHA-function class) in long-COVID patients and analyzed its association with body mass index (BMI), FEV1, forced vital capacity, other parameters of body plethysmography, diffusing capacity for carbon monoxide (DLCO), arterial blood gases, and inspiratory muscle function, assessed by airway occlusion pressure (P0.1) and maximal inspiratory pressure (PImax) in two respiratory clinics in Germany between Oct 2020 and Aug 2021. RESULTS: A total of 116 patients were included in the study. The mean age was 50.2 ± 14.5 years; BMI, 26.7 ± 5.87 kg/m2; NYHA class I, 19%; II, 27%; III, 41%; and IV, 14%. While lung function values and computed tomography or conventional X-ray of the chest were in the normal range, inspiratory muscle function was markedly impaired. P01 was elevated to 154 ± 83%predicted and PImax was reduced to 41 ± 25%predicted. PImax reduction was strongly associated with the severity of dyspnea but independent of BMI, time after acute COVID-19 and most of the other parameters. CONCLUSIONS: This study shows that in long-COVID patients, respiratory symptoms may be mainly caused by reduced inspiratory muscle strength. Assessment of PImax and P0.1 might better explain dyspnea than classical lung function tests and DLCO. A prospective study is needed to confirm these results.

Correspondence between Capnovolumetric and Conventional Lung Function Parameters in the Diagnosis of Obstructive Airway Diseases.

BACKGROUND: Capnovolumetry is of interest as a method for the diagnosis of obstructive airway diseases, requiring little cooperation from the patient. OBJECTIVE: To help in the interpretation of capnovolumetric parameters, we aimed to identify their correspondence to conventional lung function indices. METHODS: We studied 978 patients from a diagnostic study with complete functional data and the clinical diagnosis of asthma, chronic obstructive pulmonary disease (COPD), or no respiratory disease. Using path analysis, four capnovolumetric parameters (slope of expiratory phase 3, ratio of slopes of phases 3 and 2, volume of phase 2, and the ratio area/volume of phase 3) previously identified as predictors of airway obstruction in terms of spirometry and body ple-thysmography, were analyzed regarding their relationship to each other and the diagnostic categories of asthma or COPD versus control, or obstruction versus no obstruction. We then identified four lung function parameters showing relationships as much as possible isomorphic to those between capnovolumetric parameters. RESULTS: The four capnovolumetric parameters were related to COPD and obstruction via both direct and indirect influences, but only two of them to asthma. Regarding the correspondence to lung function parameters, the slope of expiratory phase 3 corresponded best to the ratio of residual volume to total lung capacity, the ratio of slopes of phases 3 and 2 to forced expiratory volume in 1 s, the volume of phase 2 to forced expired flow at 50% of vital capacity, and the ratio area/volume of phase 3 to forced vital capacity. CONCLUSIONS: Our results indicated an intricate relationship of capnovolumetric parameters to each other and to airway obstruction, asthma, or COPD. The correspondence to conventional lung function measures seemed to reflect the entities lung hyperinflation, overall ventilatory impairment, bronchoconstriction, and ventilated lung volume, in that order. These findings might be helpful for clinicians in the interpretation of capnovolumetry.

NTPDase1/CD39 and aberrant purinergic signalling in the pathogenesis of COPD.

Purinergic receptor activation via extracellular ATP is involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Nucleoside triphosphate diphosphohydrolase-1/CD39 hydrolyses extracellular ATP and modulates P2 receptor signalling.We aimed to investigate the expression and function of CD39 in the pathogenesis of cigarette smoke-induced lung inflammation in patients and preclinical mouse models. CD39 expression and soluble ATPase activity were quantified in sputum and bronchoalveolar lavage fluid (BALF) cells in nonsmokers, smokers and COPD patients or mice with cigarette smoke-induced lung inflammation. In mice, pulmonary ATP and cytokine concentrations, inflammation and emphysema were analysed in the presence or absence of CD39.Following acute cigarette smoke exposure CD39 was upregulated in BALF cells in smokers with further increases in COPD patients. Acute cigarette smoke exposure induced CD39 upregulation in murine lungs and BALF cells, and ATP degradation was accelerated in airway fluids. CD39 inhibition and deficiency led to augmented lung inflammation; treatment with ATPase during cigarette smoke exposure prevented emphysema.Pulmonary CD39 expression and activity are increased in COPD. CD39 deficiency leads to enhanced emphysema in mice, while external administration of a functional CD39 analogue partially rescues the phenotype. The compensatory upregulation of pulmonary CD39 might serve as a protective mechanism in cigarette smoke-induced lung damage.

Production of serotonin by tryptophan hydroxylase 1 and release via platelets contribute to allergic airway inflammation.

RATIONALE: 5-Hydroxytryptamine (5-HT) is involved in the pathogenesis of allergic airway inflammation (AAI). It is unclear, however, how 5-HT contributes to AAI and whether this depends on tryptophan hydroxylase (TPH) 1, the critical enzyme for peripheral 5-HT synthesis. OBJECTIVES: To elucidate the role of TPH1 and the peripheral source of 5-HT in asthma pathogenesis. METHODS: TPH1-deficient and TPH1-inhibitor-treated animals were challenged in ovalbumin and house dust mite models of AAI. Experiments with bone marrow chimera, mast cell-deficient animals, platelets transfusion, and bone marrow dendritic cells (BMDC) driven model of AAI were performed. 5-HT levels were measured in bronchoalveolar lavage fluid or serum of animals with AAI and in human asthma. MEASUREMENTS AND MAIN RESULTS: 5-HT levels are increased in bronchoalveolar lavage fluid of mice and people with asthma after allergen provocation. TPH1 deficiency and TPH1 inhibition reduced all cardinal features of AAI. Administration of exogenous 5-HT restored AAI in TPH1-deficient mice. The pivotal role of 5-HT production by structural cells was corroborated by bone marrow chimera experiments. Experiments in mast cell-deficient mice revealed that mast cells are not a source of 5-HT, whereas transfusion of platelets from wild-type and TPH1-deficient mice revealed that only platelets containing 5-HT enhanced AAI. Lack of endogenous 5-HT in vitro and in vivo was associated with an impaired Th2-priming capacity of BMDC. CONCLUSIONS: In summary, TPH1 deficiency or inhibition reduces AAI. Platelet- and not mast cell-derived 5-HT is pivotal in AAI, and lack of 5-HT leads to an impaired Th2-priming capacity of BMDC. Thus, targeting TPH1 could offer novel therapeutic options for asthma.

Safety and efficacy of exercise training in various forms of pulmonary hypertension.

The objective of this prospective study was to assess safety and efficacy of exercise training in a large cohort of patients with different forms and World Health Organization (WHO) functional classes of chronic pulmonary hypertension (PH). 183 patients with PH (pulmonary arterial hypertension (PAH), chronic thromboembolic PH and PH due to respiratory or left heart diseases received exercise training in hospital for 3 weeks and continued at home. Adverse events have been monitored during the in-hospital training programme. Efficacy parameters were evaluated at baseline, and after 3 and 15 weeks. After 3 and 15 weeks, patients significantly improved the distance walked in 6 min (6MWD) compared to baseline, scores of quality of life, WHO functional class, peak oxygen consumption, oxygen pulse, heart rate and systolic pulmonary artery pressure at rest and maximal workload. The improvement in 6MWD was similar in patients with different PH forms and functional classes. Even in severely affected patients (WHO functional class IV), exercise training was highly effective. Adverse events, such as respiratory infections, syncope or presyncope, occurred in 13% of patients. Exercise training in PH is an effective but not a completely harmless add-on therapy, even in severely diseased patients, and should be closely monitored.

Purinergic receptor inhibition prevents the development of smoke-induced lung injury and emphysema.

Extracellular ATP acts as a "danger signal" and can induce inflammation by binding to purinergic receptors. Chronic obstructive pulmonary disease is one of the most common inflammatory diseases associated with cigarette smoke inhalation, but the underlying mechanisms are incompletely understood. In this study, we show that endogenous pulmonary ATP levels are increased in a mouse model of smoke-induced acute lung inflammation and emphysema. ATP neutralization or nonspecific P2R-blockade markedly reduced smoke-induced lung inflammation and emphysema. We detected an upregulation the purinergic receptors subtypes on neutrophils (e.g., P2Y2R), macrophages, and lung tissue from animals with smoke-induced lung inflammation. By using P2Y(2)R deficient ((-/-)) animals, we show that ATP induces the recruitment of blood neutrophils to the lungs via P2Y(2)R. Moreover, P2Y(2)R deficient animals had a reduced pulmonary inflammation following acute smoke-exposure. A series of experiments with P2Y(2)R(-/-) and wild type chimera animals revealed that P2Y(2)R expression on hematopoietic cell plays the pivotal role in the observed effect. We demonstrate, for the first time, that endogenous ATP contributes to smoke-induced lung inflammation and then development of emphysema via activation of the purinergic receptor subtypes, such as P2Y(2)R.

Purinergic receptor type 6 contributes to airway inflammation and remodeling in experimental allergic airway inflammation.

RATIONALE: Extracellular nucleotides have recently been identified as proinflammatory mediators involved in asthma pathogenesis by signaling via purinergic receptors, but the role of the purinergic receptor type 6 (P2Y6R) has not been previously investigated. OBJECTIVES: To investigate the role of P2Y6R in asthma pathogenesis. METHODS: Acute and chronic OVA model and also HDM model of allergic inflammation in C57Bl/6 mice treated with specific P2Y6R antagonist and P2Y6R(-/-) mice were evaluated for classical features of asthmatic inflammation. In addition, primary epithelial cell culture from human and epithelial cell lines from mouse and human were stimulated with P2Y6R agonist and treated with P2Y6R antagonist and assessed for IL-6, IL-8/CXCL8 and KC levels. Experiments with P2Y6R(-/-) and P2Y6R(+/+) chimera were performed to discriminate the role of P2Y6R activation in structural lung cells and in cells from hematopoietic system. MEASUREMENTS AND MAIN RESULTS: We observed that the intratracheal application of a P2Y6R antagonist (MRS2578) and P2Y6R deficiency inhibited cardinal features of asthma, such as bronchoalveolar lavage eosinophilia, airway remodeling, Th2 cytokine production, and bronchial hyperresponsiveness in the ovalbumin-alum model. MRS2578 was also effective in reducing airway inflammation in a model using house dust mite extracts to induce allergic lung inflammation. Experiments with bone marrow chimeras revealed the importance of the P2Y6R expression on lung structural cells in airway inflammation. In accordance with this finding, we found a strong up-regulation of P2Y6 expression on airway epithelial cells of animals with experimental asthma. Concerning the underlying mechanism, we observed that MRS2578 inhibited the release of IL-6 and IL-8/KC by lung epithelial cells in vivo, whereas intrapulmonary application of the P2Y6R agonist uridine-5'-diphosphate increased the bronchoalveolar levels of IL-6 and KC. In addition, selective activation of P2Y6 receptors induced the release of IL-6 and KC/IL-8 by murine and human lung epithelial cells in vitro. CONCLUSIONS: P2Y6R expression on airway epithelial cells is up-regulated during acute and chronic allergic airway inflammation, and selective blocking of P2Y6R or P2Y6R deficiency on the structural cells reduces cardinal features of experimental asthma. Thus, blocking pulmonary P2Y6R might be a target for the treatment of allergic airway inflammation.

A potential role for P2X7R in allergic airway inflammation in mice and humans.

P2X7R deficiency is associated with a less severe outcome in acute and chronic inflammatory disorders. Recently, we demonstrated that extracellular adenosine triphosphate is involved in the pathogenesis of asthma by modulating the function of dendritic cells (DCs). However, the role of the purinergic receptor subtype P2X7 is unknown. To elucidate the role of P2X7R in allergic airway inflammation (AAI) in vitro and in vivo, P2X7R expression was measured in lung tissue and immune cells of mice or in humans with allergic asthma. By using a specific P2X7R-antagonist and P2X7R-deficient animals, the role of this receptor in acute and chronic experimental asthma was explored. P2X7R was found to be up-regulated during acute and chronic asthmatic airway inflammation in mice and humans. In vivo experiments revealed the functional relevance of this finding because selective P2X7R inhibition or P2X7R deficiency was associated with reduced features of acute and chronic asthma in the ovalbumin-alum or HDM model of AAI. Experiments with bone marrow chimeras emphasized that P2X7R expression on hematopoietic cells is responsible for the proasthmatic effects of P2X7R signaling. In the DC-driven model of AAI, P2X7R-deficient DCs showed a reduced capacity to induce Th2 immunity in vivo. Up-regulation of P2X7R on BAL macrophages and blood eosinophils could be observed in patients with chronic asthma. Our data suggest that targeting P2X7R on hematopoietic cells (e.g., DCs or eosinophils) might be a new therapeutic option for the treatment of asthma.

P2X7 receptor signaling in the pathogenesis of smoke-induced lung inflammation and emphysema.

Extracellular ATP is up-regulated in the airways of patients with chronic obstructive pulmonary disease, and may contribute to the pathogenesis of the disease. However, the precise mechanisms are poorly understood. Our objective was to investigate the functional role of the ATP receptor P2X(7) in the pathogenesis of cigarette smoke (CS)-induced lung inflammation and emphysema in vivo. Expression of the P2X(7) receptor (P2X(7)R) was measured in lung tissue und immune cells of mice with CS-induced lung inflammation. In a series of experiments using P2X(7) antagonists and genetically engineered mice, the functional role of the P2X(7)R in CS-induced lung inflammation was explored. CS-induced inflammation was associated with an up-regulation of the P2X(7)R on blood and airway neutrophils, alveolar macrophages, and in whole lung tissue. Selective intrapulmonary inhibition of the P2X(7)R reduced CS-induced lung inflammation and prevented the development of emphysema. Accordingly, P2X(7)R knockout mice showed a reduced pulmonary inflammation after acute CS exposure. Experiments with P2X(7)R chimera animals revealed that immune cell P2X(7)R expression plays an important role in CS-induced lung inflammation and emphysema. Extracellular ATP contributes to the development of CS-induced lung inflammation and emphysema via activation of the P2X(7)R. Inhibition of this receptor may be a new therapeutic target for the treatment of chronic obstructive pulmonary disease.

Increased platelet, leukocyte and endothelial microparticles predict enhanced coagulation and vascular inflammation in pulmonary hypertension.

Pulmonary hypertension (PH) is associated with platelet activation, vascular inflammation and endothelial dysfunction leading to often life threatening thrombo-embolic complications. Microparticles (MPs) are cell vesicles with strong coagulatory and inflammatory effects being released during cell activation and apoptosis. As there are currently no established surrogate markers predicting platelet activation and pro-coagulation in PH patients, the aim of the study was to analyze different pro-coagulatory MP populations that might be related to thrombo-embolic complications in PH patients. Circulating MPs from platelet- (PMP, CD31(+)/61(+)), leukocyte- (LMP, CD11b(+)) and endothelial- (EMP, CD62E(+)) origin were measured by flow cytometry in 19 PH patients and were compared to 16 controls. PH patients had increased levels of PMP (PH vs. control 1,016 ± 201 vs. 527 ± 59 counts per min [cpm], P = 0.032), LMP (PH vs. control 31 ± 3 cpm vs. 18 ± 2 cpm, P = 0.001) and EMP (PH vs. control 99 ± 14 cpm vs. 46 ± 6 cpm, P = 0.001). Furthermore, PMP correlated to LMP (PMP vs. LMP: r = 0.75, P < 0.001) and LMP correlated to EMP levels (LMP vs. EMP, r = 0.74, P < 0.001) indicating a functional interaction between the different types of MP. In comparison to non-embolic PH patients, patients with a thrombo-embolic PH suffered from enhanced endothelial cell dysfunction as represented by significantly increased EMP levels (thrombo-embolic PH vs. non-embolic PH 137 ± 27 vs. 72 ± 10, P = 0.02). PH patients have increased levels of platelet-, leukocyte- and endothelial MP indicating an increased vascular pro-coagulation and inflammation which might be related to thrombo-embolic complications as well as PH progression.

Extracellular adenosine triphosphate and chronic obstructive pulmonary disease.

RATIONALE: Extracellular ATP promotes inflammation, but its role in chronic obstructive pulmonary disease (COPD) is unknown. OBJECTIVES: To analyze the expression of ATP and its functional consequences in never-smokers, asymptomatic smokers, and patients with COPD. METHODS: ATP was quantified in bronchoalveolar lavage fluid (BALF) of never-smokers, asymptomatic smokers, and patients with COPD of different severity. The expression of specific ATP (purinergic) receptors was measured in airway macrophages and blood neutrophils from control subjects and patients with COPD. The release of mediators by macrophages and neutrophils and neutrophil chemotaxis was assessed after ATP stimulation. MEASUREMENTS AND MAIN RESULTS: Chronic smokers had elevated ATP concentrations in BALF compared with never-smokers. Acute smoke exposure led to a further increase in endobronchial ATP concentrations. Highest ATP concentrations in BALF were present in smokers and ex-smokers with COPD. In patients with COPD, BALF ATP concentrations correlated negatively with lung function and positively with BALF neutrophil counts. ATP induced a stronger chemotaxis and a stronger elastase release in blood neutrophils from patients with COPD, as compared with control subjects. In addition, airway macrophages from patients with COPD responded with an increased secretion of proinflammatory and tissue-degrading mediators after ATP stimulation. These findings were accompanied by an up-regulation of specific purinergic receptors in blood neutrophils and airway macrophages of patients with COPD. CONCLUSIONS: COPD is characterized by a strong and persistent up-regulation of extracellular ATP in the airways. Extracellular ATP appears to contribute to the pathogenesis of COPD by promoting inflammation and tissue degradation.

Activation of human alveolar macrophages via P2 receptors: coupling to intracellular Ca2+ increases and cytokine secretion.

Alveolar macrophages play a crucial role in the pathogenesis of inflammatory airway diseases. By the generation and release of different inflammatory mediators they contribute to both recruitment of different leukocytes into the lung and to airway remodeling. A potent stimulus for the release of inflammatory cytokines is ATP, which mediates its cellular effects through the interaction with different membrane receptors, belonging to the P2X and P2Y families. The aim of this study was to characterize the biological properties of purinoceptors in human alveolar macrophages obtained from bronchoalveolar lavages in the context of inflammatory airway diseases. The present study is the first showing that human alveolar macrophages express mRNA for different P2 subtypes, namely P2X(1), P2X(4), P2X(5), P2X(7), P2Y(1), P2Y(2), P2Y(4), P2Y(6), P2Y(11), P2Y(13), and P2Y(14). We also showed that extracellular ATP induced Ca(2+) transients and increased IL-1beta secretion via P2X receptors. Furthermore, extracellular nucleotides inhibited production of IL-12p40 and TNF-alpha, whereas IL-6 secretion was up-regulated. In summary, our data further support the hypothesis that purinoceptors are involved in the pathogenesis of inflammatory lung diseases.

Definition, clinical classification and initial diagnosis of pulmonary hypertension: Updated recommendations from the Cologne Consensus Conference 2018.

In the summer of 2016, delegates from the German Society of Cardiology (DGK), the German Respiratory Society (DGP), and the German Society of Pediatric Cardiology (DGPK) met in Cologne, Germany, to define consensus-based practice recommendations for the management of patients with pulmonary hypertension (PH). These recommendations were built on the 2015 European Pulmonary Hypertension guidelines, aiming at their practical implementation, considering country-specific issues, and including new evidence, where available. To this end, a number of working groups was initiated, one of which was specifically dedicated to the definition, clinical classification and initial diagnosis of PH. While the European guidelines provide a detailed clinical classification and a structured approach for diagnostic testing, their application in routine care may be challenging, particularly given the changing phenotype of PH patients who are nowadays often elderly and may present with multiple potential causes of PH, as well as comorbid conditions. Specifically, the working group addresses the thoroughness of diagnostic testing, and the roles of echocardiography, exercise testing, and genetic testing in diagnosing PH. Furthermore, challenges in the diagnostic work-up of patients with various causes of PH including "PAH with comorbidities", CTEPH and coexisting conditions are highlighted, and a modified diagnostic algorithm is provided. The detailed results and recommendations of the working group on definition, clinical classification and initial diagnosis of PH, which were last updated in the spring of 2018, are summarized in this article.

IL-6 and IL-8 release is mediated via multiple signaling pathways after stimulating dendritic cells with lysophospholipids.

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive lipid mediators, which are known to play major roles in allergic reactions as well as in tumor pathogenesis. Here, the biological activities and signal pathways of these lysophospholipids (LPLs) in dendritic cells (DCs) were characterized further. Flow cytometric and immunoblot analyses indicate that immature as well as mature DCs express the LPL receptors S1P1, S1P3, S1P5, and LPA2, but not S1P2, S1P4, LPA1, or LPA3. Moreover, enzyme-linked immunosorbent assay experiments demonstrate that simultaneous addition of these LPLs to immature DCs in the presence of lipopolysaccharide enhanced the secretion of the inflammatory cytokines interleukin (IL)-6 and IL-8 in maturing DCs. In contrast, no modification of IL-6 or IL-8 release was observed after exposure of mature DCs to LPLs alone. In addition, studies with pertussis toxin and mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059 suggested that Gi proteins and MAPK pathway are involved in these LPL-induced cell responses. Corroborating these findings, we observed that LPLs induce the phosphorylation of extracellular signal-regulated kinase 1/2 in immature DCs but not in mature DCs. Further analyses show that inhibitors of phosholipase D, Rho, and protein kinase C also inhibited the LPL-induced release of IL-6 and IL-8. Therefore, our findings suggest that lipopolysaccharide in DCs uncouples LPL receptors from the signal-transducing machinery during maturation and that exposure of LPLs at early time-points to maturing DCs modifies the proinflammatory capacity of mature DCs.