Prognostic value of tricuspid valve regurgitation in patients with pulmonary arterial hypertension and CTEPH: A longitudinal study.

Aims: The prognostic value of functional tricuspid valve regurgitation (TR) in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (CTEPH) remains undetermined. This study primarily aims to quantify the prognostic role of TR in relation to right ventricle (RV) dysfunction on clinical outcomes and secondarily the evolution of TR and RV dysfunction over time. Methods: Adult PAH or CTEPH patients diagnosed by right heart catheterization were included. Exclusion criteria were prevalent patients and age < 18 years.The primary endpoint was a composite of death or lung transplantation. Longitudinal evolution of TR and RV dysfunction were modelled with generalized mixed-effect models, which were inserted in a cox model under the joint-modelling framework in order to investigate the association of TR and RV dysfunction with the endpoint. Results: We included 76 PAH and 44 CTEPH patients (median age:59, females:62 %), with a mean follow-up of 3.2 ± 2.1 years. 31 patients reached the endpoint (2 transplant, 29 mortality). On average the probability of moderate-to-severe TR decreased during follow-up, whereas the probability of moderate-to-severe RV dysfunction remained stable. The cumulative effect of moderate-to-severe TR (HRper day 1.01 95 %CI[1.00-1.01],P < 0.001) and moderate-to-severe RV dysfunction (HRper day: 1.01 95 %CI[1.00-1.01],P < 0.001) was associated with the endpoint in univariable joint-models. In a multivariable joint-model with both the evolutions of TR and RV dysfunction only TR remained significant (HR per day: 1.01 95 %CI[1.00-1.01],P < 0.001). Conclusion: Persistent moderate-to-severe tricuspid valve regurgitation during follow-up predicts adverse outcomes and might be a better predictor of lung transplantation and mortality compared to right ventricle dysfunction.

Plasma Dephosphorylated-Uncarboxylated Matrix Gla-Protein in Systemic Sclerosis Patients: Biomarker Potential for Vascular Calcification and Inflammation.

BACKGROUND: Systemic sclerosis (SSc) patients face an elevated risk of cardiovascular disease (CVD), even when classic cardiovascular risk factors are considered. Plasma dephosphorylated-uncarboxylated Matrix Gla-protein (dp-ucMGP), an inactive form of MGP, is associated with increased CVD risk. Smooth muscle cells, implicated in SSc's development, are the primary dp-ucMGP producers. This study assessed dp-ucMGP levels and initial CVD events in early-diagnosed SSc patients, investigating its potential as a CVD and all-cause mortality predictor over time. METHODS: In a cohort of 87 SSc patients (excluding those with pre-existing CVD or on dialysis), baseline dp-ucMGP levels were measured, along with cardiovascular risk factors. Validation involved assessing dp-ucMGP in a subset of treatment-naive SSc patients. RESULTS: A significantly elevated median dp-ucMGP level of 634 pmol/L (IQR 301) compared with healthy controls (dp-ucMGP < 393 pmol/L; p < 0.001) was observed. Validation in a treatment-naive SSc patient subset yielded similar results (median 589 pmol/L; IQR 370). During a median 10.5-year follow-up among 78 SSc patients, 33.3% experienced their first CVD event, independent of traditional risk factors. Elevated dp-ucMGP levels (>634 pmol/L) correlated with a higher risk of CVD and/or death (log-rank test: p < 0.01). CONCLUSIONS: In summary, dp-ucMGP emerges as a novel biomarker in SSc patients, with elevated levels indicating an increased risk of CVD and/or mortality in this population.

Sexual function is impaired in women and men with pulmonary hypertension.

BACKGROUND: Sexual health related quality of life (SHRQoL) is an important pillar of health related quality of life (HRQoL). The aim of this study was to investigate sexual functioning in men and women with pulmonary hypertension (PH). METHODS AND RESULTS: In this cross-sectional study, a total of 78 patients were included, 49 were diagnosed with pulmonary arterial hypertension and 29 with chronic thromboembolic pulmonary hypertension (median age 53 [IQR: 46-67 years], 66.7% female). All patients completed SHRQoL questionnaires; for women: ASEX, FSFI, and FSDS and for men: ASEX and IIEF. A PH-specific SHRQoL questionnaire was created based on 4 semi-structured interviews to investigate PH-specific barriers in sexuality. More than half of the patients experienced symptoms during sexual activity, mainly dyspnea (52.6%) and palpitations (32.1%). Sexual dysfunction was present, according to the FSFI-questionnaire, in 63.0% of women. All of the men experienced at least mild dysfunction in one of the domains of the IIEF and erectile dysfunction was present in 48.0%. Sexual dysfunction occurred more often in both men and women with PH than in the general population. PAH-specific medication was not associated with sexual dysfunction, nor was subcutaneous or intravenous pump therapy (OR 1.14, 95%-CI: 0.75-1.73). Diuretics were associated with sexual dysfunction in women (OR 4.01, 95%-CI: 1.04-15.41). Of all patients committed in a relationship, 69.0% would like to discuss sexuality with their healthcare provider. CONCLUSION: This study showed a high prevalence of sexual dysfunction in men and women with PH. It is important for healthcare providers to discuss sexuality with patients.

Role of the electrocardiogram in the risk stratification of pulmonary hypertension.

INTRODUCTION: The prognosis of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) remains dismal. Better risk prediction is needed. This study investigated the prognostic value of ECG characteristics. METHODS: In this single-centre prospective study, consecutive treatment-naïve patients with PAH or CTEPH were included at time of diagnosis. From the 12-lead ECG, obtained at baseline, the following parameters were collected: heart rate (HR), rhythm, QRS axis, conduction times, P-top amplitudes in II, R-top and S-wave amplitudes in V1 and V5 and repolarisation disorders. Associations between the ECG and transplant-free survival was assessed by Kaplan-Meier curves and Cox-proportional hazard regressions. RESULTS: In total, 140 patients were included (median age: 60.7 years, 63.6% female). The ECG was abnormal in 86.2%: sinus rhythm was not present in 9.3%, right QRS axis was observed in 47.8%, mean QRS duration was 101±17 ms. Only 42.5% of the patients had normal repolarisation, 34.5% had right ventricular strain and 14.4% non-specific repolarisation disorders. Over a median follow-up time of 3.49 (IQR: 1.37-6.42) years, 45 patients (32.5%) died or underwent lung transplantation. Transplant-free survival was worse in patients presenting with an abnormal ECG (64.0% vs 86.0%; p=0.037). The following ECG characteristics were associated with all-cause mortality or lung transplantation: heart rate (HR 1.02, 95% CI: 1.00 to 1.05), QRS duration >120 ms (HR 2.61, 95% CI: 1.01 to 6.71) and S-wave amplitude in V5 (HR 1.10, 95% CI: 1.04 to 1.17). CONCLUSION: Only 13.8% of patients with PAH and CTEPH presented with a normal ECG, which is associated with favourable outcome. The ECG provides additional prognostic value to current clinical parameters and should be considered in risk prediction.

The evolution of survival of pulmonary arterial hypertension over 15 years.

The prognosis of pulmonary arterial hypertension (PAH) remains dismal. Over the years, multiple therapeutic advances have been introduced. This study evaluates the evolution of PAH survival over the past 15 years. We included 293 consecutive adult patients diagnosed with PAH between 2005 and 2019 (median age: 61.8 years, 70.3% female). Patients were divided into three cohorts based on the time of diagnosis: 2005-2009, 2010-2014, and 2015-2019 (2005-2009: n = 56; 2010-2014: n = 111; 2015-2019: n = 126). Transplant-free survival was measured from the date of right heart catheterization until patients reached the composite endpoint of lung transplant or death. Multivariable cox-pulmonary hypertension regression was used to study the effect of the time of diagnosis. The final cox model was fitted in both younger and older patients to evaluate the difference between these groups. During a median follow-up time of 4.1 (interquartile range: 2.2-7.3) years, 9 patients underwent lung transplantation and 151 patients died. The median overall transplant-free survival was 6.2 (5.5-8.0) years. Patients older than 56 years at baseline who were diagnosed in 2005-2009 showed better survival compared to patients diagnosed in 2010-2014 and 2015-2019 with an adjusted hazard ratio of, respectively, 2.12 (1.11-4.03) and 2.83 (1.41-5.69). Patients younger than 56 years showed neither an improved nor deteriorated survival over time. In conclusion, survival in patients with PAH did not improve over time, despite more available therapeutic options. This might be partly due to the changed demographic characteristics of the PAH patients and a still important diagnostic delay.

Kynurenine metabolites predict survival in pulmonary arterial hypertension: A role for IL-6/IL-6Rα.

Activation of the kynurenine pathway (KP) has been reported in patients with pulmonary arterial hypertension (PAH) undergoing PAH therapy. We aimed to determine KP-metabolism in treatment-naïve PAH patients, investigate its prognostic values, evaluate the effect of PAH therapy on KP-metabolites and identify cytokines responsible for altered KP-metabolism. KP-metabolite levels were determined in plasma from PAH patients (median follow-up 42 months) and in rats with monocrotaline- and Sugen/hypoxia-induced PH. Blood sampling of PAH patients was performed at the time of diagnosis, six months and one year after PAH therapy. KP activation with lower tryptophan, higher kynurenine (Kyn), 3-hydroxykynurenine (3-HK), quinolinic acid (QA), kynurenic acid (KA), and anthranilic acid was observed in treatment-naïve PAH patients compared with controls. A similar KP-metabolite profile was observed in monocrotaline, but not Sugen/hypoxia-induced PAH. Human lung primary cells (microvascular endothelial cells, pulmonary artery smooth muscle cells, and fibroblasts) were exposed to different cytokines in vitro. Following exposure to interleukin-6 (IL-6)/IL-6 receptor α (IL-6Rα) complex, all cell types exhibit a similar KP-metabolite profile as observed in PAH patients. PAH therapy partially normalized this profile in survivors after one year. Increased KP-metabolites correlated with higher pulmonary vascular resistance, shorter six-minute walking distance, and worse functional class. High levels of Kyn, 3-HK, QA, and KA measured at the latest time-point were associated with worse long-term survival. KP-metabolism was activated in treatment-naïve PAH patients, likely mediated through IL-6/IL-6Rα signaling. KP-metabolites predict response to PAH therapy and survival of PAH patients.

Peripheral Blood T Cells of Patients with IPAH Have a Reduced Cytokine-Producing Capacity.

Pulmonary arterial hypertension (PAH) is rare disease that is categorized as idiopathic (IPAH) when no underlying cause can be identified. Lungs of most patients with IPAH contain increased numbers of T cells and dendritic cells (DCs), suggesting involvement of the immune system in its pathophysiology. However, our knowledge on circulating immune cells in IPAH is rather limited. We used flow cytometry to characterize peripheral blood DCs and T cells in treatment-naive IPAH patients, compared with connective-tissue disease-PAH (CTD-PAH) patients and healthy controls (HCs). At diagnosis, T-helper (Th) cells of IPAH patients were less capable of producing TNFα, IFNγ, IL-4 and IL-17 compared to HCs. IPAH patients showed a decreased frequency of Th2 cells and significantly enhanced expression of the CTLA4 checkpoint molecule in naive CD4+ T cells and both naive and memory CD8+ T cells. Frequencies and surface marker expression of circulating DCs and monocytes were essentially comparable between IPAH patients and HCs. Principal component analysis (PCA) separated IPAH patients-but not CTD-PAH patients-from HCs, based on T-cell cytokine profiles. At 1-year follow-up, the frequencies of IL-17+ production by memory CD4+ T cells were increased in IPAH patients and accompanied by increased proportions of Th17 and Tc17 cells, as well as decreased CTLA4 expression. Treatment-naive IPAH patients displayed a unique T-cell phenotype that was different from CTD-PAH patients and was characterized by reduced cytokine-producing capacity. These findings point to involvement of adaptive immune responses in IPAH, which may have an implication for the development of therapeutic interventions.

Evidence for a Role of CCR6+ T Cells in Chronic Thromboembolic Pulmonary Hypertension.

Introduction: Previous studies have shown an increase of T cells and chemokines in vascular lesions of patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, detailed characterization of these T cells is still lacking, nor have treatment effects been evaluated. Methods: We included 41 treatment-naive CTEPH patients at diagnosis, 22 patients at 1-year follow-up, and 17 healthy controls (HCs). Peripheral blood T cells were characterized by flow cytometry for subset distribution, cytokine expression and activation marker profile. We used multiplex immunofluorescence to identify CCR6+ T cells in endarterectomy tissue from 25 patients. Results: At diagnosis, proportions of CCR6+ CD4+ T cells were increased in CTEPH patients compared with HCs. Patients displayed a significantly reduced production capacity of several cytokines including TNFα, IFNγ, GM-CSF and IL-4 in CD4+ T cells, and TNFα and IFNγ in CD8+ T cells. CD4+ and CD8+ T cells showed increased expression of the immune checkpoint protein CTLA4. Multivariate analysis separated CTEPH patients from HCs, based on CCR6 and CTLA4 expression. At 1-year follow-up, proportions of CCR6+CD4+ T cells were further increased, IFNγ and IL-17 production capacity of CD4+ T cells was restored. In nearly all vascular lesions we found substantial numbers of CCR6+ T cells. Conclusion: The observed increase of CCR6+ T cells and modulation of the IFNγ and IL-17 production capacity of circulating CD4+ T cells at diagnosis and 1-year follow-up - together with the presence of CCR6+ T cells in vascular lesions - support the involvement of the Th17-associated CCR6+ T cell subset in CTEPH.

Prognostic value of brain natriuretic peptides in patients with pulmonary arterial hypertension: A systematic review and meta-analysis.

BACKGROUND: Multiple biomarkers have been investigated in the risk stratification of patients with pulmonary arterial hypertension (PAH). This systematic review and meta-analysis is the first to investigate the prognostic value of (NT-pro)BNP in patients with PAH. METHODS: A systematic literature search was performed using MEDLINE, Embase, Web of Science, the Cochrane Library and Google scholar to identify studies on the prognostic value of baseline (NT-pro)BNP levels in PAH. Studies reporting hazard ratios (HR) for the endpoints mortality or lung transplant were included. A random effects meta-analysis was performed to calculate the pooled HR of (NT-pro)BNP levels at the time of diagnosis. To account for different transformations applied to (NT-pro)BNP, the HR was calculated for a 2-fold difference of the weighted mean (NT-pro)BNP level of 247 pmol/L, for studies reporting a HR based on a continuous (NT-pro)BNP measurement. RESULTS: Sixteen studies were included, representing 6999 patients (mean age 45.2-65.0 years, 97.3% PAH). Overall, 1460 patients reached the endpoint during a mean follow-up period between 1 and 10 years. Nine studies reported HRs based on cut-off values. The risk of mortality or lung transplant was increased for both elevated NT-proBNP and BNP with a pooled HR based on unadjusted HRs of 2.75 (95%-CI: 1.86-4.07) and 3.87 (95% CI 2.69-5.57) respectively. Six studies reported HRs for (NT-pro)BNP on a continues scale. A 2-fold difference of the weighted mean NT-proBNP resulted in an increased risk of mortality or lung transplant with a pooled HR of 1.17 (95%-CI: 1.03-1.32). CONCLUSIONS: Increased levels of (NT-pro)BNP are associated with a significantly increased risk of mortality or lung transplant in PAH patients.

Prevalence of Micronutrient Deficiencies and Relationship with Clinical and Patient-Related Outcomes in Pulmonary Hypertension Types I and IV.

BACKGROUND: Pulmonary hypertension (PH) is a rare progressive and lethal disease affecting pulmonary arteries and heart function. The disease may compromise the nutritional status of the patient, which impairs their physical performance. This study aimed to determine the prevalence of micronutrient deficiencies in pulmonary arterial hypertension (PAH) and chronic thrombo-embolic pulmonary hypertension (CTEPH) patients. METHODS: Eighty-one blood samples from a prospective observational cohort study were analyzed for concentrations of micronutrients and inflammation-related factors. The samples consisted of newly diagnosed (treatment-naive) PAH and CTEPH patients and patients treated for 1.5 years according to ERS/ESC guidelines. RESULTS: In the newly diagnosed group, 42% of PAH patients and 21% of CTEPH patients were iron deficient compared to 29% of PAH patients and 20% of CTEPH patients in the treatment group. Vitamin D deficiency occurred in 42% of the newly diagnosed PAH patients, 71% of the newly diagnosed CTEPH patients, 68% of the treated PAH patients, and 70% of the treated CTEPH patients. Iron levels correlated with the 6 min walking distance (6MWD). CONCLUSIONS: Iron and vitamin D deficiencies are highly prevalent in PAH and CTEPH patients, underlining the need for monitoring their status. Studies evaluating the effects of supplementation strategies for iron and vitamin D are necessary.

The longitudinal use of EmPHasis-10 and CAMPHOR questionnaire health-related quality of life scores in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

BACKGROUND: Health-related quality of life (HRQoL) is impaired in patients with pulmonary hypertension (PH). The EmPHasis-10 and CAMPHOR questionnaires are developed to evaluate HRQoL specifically in patients with PH. Data on the longitudinal use of both questionnaires are still limited. We evaluated the longitudinal value of both questionnaires and established minimal clinically important differences (MCID). METHODS: Sixty-one treatment naïve pulmonary arterial hypertension or chronic thromboembolic patients were prospectively included. Patients were treated according to the current ESC/ERS guidelines. We compared EmPHasis-10 and CAMPHOR scores between baseline, 6 and 12 months of follow-up and evaluated the correlation between these scores and a 5-scale symptom severity score, 5-scale overall health score, NYHA-classification, 6 min walk test distance (6MWD), NT-proBNP and echocardiographic parameters. RESULTS: After one year of treatment a significant reduction in EmPHasis-10 score and CAMPHOR QoL and symptoms domain score was observed. Moderate to good correlations were observed between the questionnaires and the overall-health and symptom severity score and 6MWD. No relevant correlations were seen between the questionnaires and NT-pro-BNP and echocardiographic parameters. EmPHasis-10 scores showed strong correlations with all CAMPHOR domains. The MCID for the EmPHasis-10 questionnaire was -8. The MCIDs for the CAMPHOR domains were: activity -3, symptoms -4, QoL -3. CONCLUSION: The EmPHasis-10 and CAMPHOR questionnaires are valid tools for the longitudinal measurement of HRQoL in patients with PH. The much shorter EmPHasis-10 correlates well with the CAMPHOR domain scores and with the clinical endpoints and it may be easier to use in daily practice.

Imatinib in patients with severe COVID-19: a randomised, double-blind, placebo-controlled, clinical trial.

BACKGROUND: The major complication of COVID-19 is hypoxaemic respiratory failure from capillary leak and alveolar oedema. Experimental and early clinical data suggest that the tyrosine-kinase inhibitor imatinib reverses pulmonary capillary leak. METHODS: This randomised, double-blind, placebo-controlled, clinical trial was done at 13 academic and non-academic teaching hospitals in the Netherlands. Hospitalised patients (aged ≥18 years) with COVID-19, as confirmed by an RT-PCR test for SARS-CoV-2, requiring supplemental oxygen to maintain a peripheral oxygen saturation of greater than 94% were eligible. Patients were excluded if they had severe pre-existing pulmonary disease, had pre-existing heart failure, had undergone active treatment of a haematological or non-haematological malignancy in the previous 12 months, had cytopenia, or were receiving concomitant treatment with medication known to strongly interact with imatinib. Patients were randomly assigned (1:1) to receive either oral imatinib, given as a loading dose of 800 mg on day 0 followed by 400 mg daily on days 1-9, or placebo. Randomisation was done with a computer-based clinical data management platform with variable block sizes (containing two, four, or six patients), stratified by study site. The primary outcome was time to discontinuation of mechanical ventilation and supplemental oxygen for more than 48 consecutive hours, while being alive during a 28-day period. Secondary outcomes included safety, mortality at 28 days, and the need for invasive mechanical ventilation. All efficacy and safety analyses were done in all randomised patients who had received at least one dose of study medication (modified intention-to-treat population). This study is registered with the EU Clinical Trials Register (EudraCT 2020-001236-10). FINDINGS: Between March 31, 2020, and Jan 4, 2021, 805 patients were screened, of whom 400 were eligible and randomly assigned to the imatinib group (n=204) or the placebo group (n=196). A total of 385 (96%) patients (median age 64 years [IQR 56-73]) received at least one dose of study medication and were included in the modified intention-to-treat population. Time to discontinuation of ventilation and supplemental oxygen for more than 48 h was not significantly different between the two groups (unadjusted hazard ratio [HR] 0·95 [95% CI 0·76-1·20]). At day 28, 15 (8%) of 197 patients had died in the imatinib group compared with 27 (14%) of 188 patients in the placebo group (unadjusted HR 0·51 [0·27-0·95]). After adjusting for baseline imbalances between the two groups (sex, obesity, diabetes, and cardiovascular disease) the HR for mortality was 0·52 (95% CI 0·26-1·05). The HR for mechanical ventilation in the imatinib group compared with the placebo group was 1·07 (0·63-1·80; p=0·81). The median duration of invasive mechanical ventilation was 7 days (IQR 3-13) in the imatinib group compared with 12 days (6-20) in the placebo group (p=0·0080). 91 (46%) of 197 patients in the imatinib group and 82 (44%) of 188 patients in the placebo group had at least one grade 3 or higher adverse event. The safety evaluation revealed no imatinib-associated adverse events. INTERPRETATION: The study failed to meet its primary outcome, as imatinib did not reduce the time to discontinuation of ventilation and supplemental oxygen for more than 48 consecutive hours in patients with COVID-19 requiring supplemental oxygen. The observed effects on survival (although attenuated after adjustment for baseline imbalances) and duration of mechanical ventilation suggest that imatinib might confer clinical benefit in hospitalised patients with COVID-19, but further studies are required to validate these findings. FUNDING: Amsterdam Medical Center Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek/ZonMW, and the European Union Innovative Medicines Initiative 2.

Loss of immune homeostasis in patients with idiopathic pulmonary arterial hypertension.

INTRODUCTION: Autoreactivity against pulmonary vascular structures is thought to be involved in idiopathic pulmonary arterial hypertension (IPAH), but the underlying mechanisms remain poorly understood. We hypothesised that aberrant B-cell activation contributes to IPAH aetiology. METHODS: Mice with enhanced B-cell activation due to B-cell-specific overexpression of the B-cell receptor (BCR) signalling molecule Bruton's tyrosine kinase (BTK) were subjected to lung injury and examined for several pulmonary hypertension (PH) indices. Peripheral blood lymphocytes from patients with IPAH (n=13), connective tissue disease-associated PAH (CTD-PAH, n=9), congenital heart disease PAH (n=7), interstitial lung disease associated PH (n=17) and healthy controls (n=19) were characterised by 14-colour flow cytometry. RESULTS: Following pulmonary injury, BTK-overexpressing mice showed prolonged activation of B cells and CXCR5+ follicular T-helper (Tfh) cells, as well as features of PH development. Patients with CTD-PAH and CHD-PAH displayed reduced proportions of circulating non-switched-memory B cells (p=0.03, p=0.02, respectively). Interestingly, we observed increased BTK protein expression in naive (p=0.007) and memory B-cell subsets of patients with IPAH and CTD-PAH. BTK was particularly high in patients with IPAH with circulating autoantibodies (p=0.045). IPAH patients had low frequencies of circulating CXCR5+ Tfh cells (p=0.005). Hereby, the increased BTK protein expression in B cells was associated with high proportions of Tfh17 (p=0.018) and Tfh17.1 (p=0.007) cells within the circulating Tfh population. CONCLUSIONS: Our study shows that pulmonary injury in combination with enhanced B-cell activation is sufficient to induce PH symptoms in mice. In parallel, immune homeostasis in patients with IPAH is compromised, as evidenced by increased BCR signalling and cTfh17 polarisation, indicating that adaptive immune activation contributes to IPAH disease induction or progression.

Central Role of Dendritic Cells in Pulmonary Arterial Hypertension in Human and Mice.

The pathogenesis of idiopathic pulmonary arterial hypertension (IPAH) is not fully understood, but evidence is accumulating that immune dysfunction plays a significant role. We previously reported that 31-week-old Tnfaip3DNGR1-KO mice develop pulmonary hypertension (PH) symptoms. These mice harbor a targeted deletion of the TNFα-induced protein-3 (Tnfaip3) gene, encoding the NF-κB regulatory protein A20, specifically in type I conventional dendritic cells (cDC1s). Here, we studied the involvement of dendritic cells (DCs) in PH in more detail. We found various immune cells, including DCs, in the hearts of Tnfaip3DNGR1-KO mice, particularly in the right ventricle (RV). Secondly, in young Tnfaip3DNGR1-KO mice, innate immune activation through airway exposure to toll-like receptor ligands essentially did not result in elevated RV pressures, although we did observe significant RV hypertrophy. Thirdly, PH symptoms in Tnfaip3DNGR1-KO mice were not enhanced by concomitant mutation of bone morphogenetic protein receptor type 2 (Bmpr2), which is the most affected gene in PAH patients. Finally, in human IPAH lung tissue we found co-localization of DCs and CD8+ T cells, representing the main cell type activated by cDC1s. Taken together, these findings support a unique role of cDC1s in PAH pathogenesis, independent of general immune activation or a mutation in the Bmpr2 gene.

DNGR1-Cre-mediated Deletion of Tnfaip3/A20 in Conventional Dendritic Cells Induces Pulmonary Hypertension in Mice.

Chronic perivascular inflammation is a prominent feature in the lungs of idiopathic pulmonary arterial hypertension. Although the proportions of conventional dendritic cells (cDCs) and plasmacytoid DCs are increased in idiopathic pulmonary arterial hypertension lungs, it remains unknown whether activated cDCs play a pathogenic role. The Tnfaip3 gene encodes the ubiquitin-binding protein A20, which is a negative regulator of NF-κB, critically involved in DC activation. Targeting of Tnfaip3/A20 in cDCs was achieved by Clec9a (DNGR1)-Cre-mediated excision of the Tnfaip3 gene in Tnfaip3DNGR1-KO mice. Mice were evaluated for signs of pulmonary hypertension (PH) using right heart catheterization, echocardiography, and measurement of the Fulton index. Inflammation was assessed by immunohistochemistry and flow cytometry. Pulmonary cDCs and monocyte-derived DCs from 31-week-old Tnfaip3DNGR1-KO mice showed modulated expression of cell surface activation markers compared with Tnfaip3DNGR1-WT mice. Tnfaip3DNGR1-KO mice developed elevated right ventricular systolic pressure and right ventricular hypertrophy. The lungs of these mice displayed increased vascular remodeling and perivascular and peribronchial immune cell infiltration resembling tertiary lymphoid organs. Proportions of activated T cells and expression of IL-1ß, IL-6, and IL-10 were enhanced in the lungs of Tnfaip3DNGR1-KO mice. Autoreactive IgA and IgG1 was detected in BAL and autoreactive IgA recognizing pulmonary endothelial antigens was present in the serum of Tnfaip3DNGR1-KO mice. All signs of PH were ameliorated in Tnfaip3DNGR1-KO mice by anti-IL-6 antibody treatment. These results indicate that activation of the NF-κB pathway in DCs, through deletion of A20/Tnfaip3, leads to experimental PH with accompanied pulmonary inflammation in an IL-6-dependent fashion.

Lower Plasma Melatonin Levels Predict Worse Long-Term Survival in Pulmonary Arterial Hypertension.

: Exogenous melatonin has been reported to be beneficial in the treatment of pulmonary hypertension (PH) in animal models. Multiple mechanisms are involved, with melatonin exerting anti-oxidant and anti-inflammatory effects, as well as inducing vasodilation and cardio-protection. However, endogenous levels of melatonin in treatment-naïve patients with PH and their clinical significance are still unknown. Plasma levels of endogenous melatonin were measured by liquid chromatography-tandem mass spectrometry in PH patients (n = 64, 43 pulmonary arterial hypertension (PAH) and 21 chronic thromboembolic PH (CTEPH)) and healthy controls (n = 111). Melatonin levels were higher in PH, PAH, and CTEPH patients when compared with controls (Median 118.7 (IQR 108.2-139.9), 118.9 (109.3-147.7), 118.3 (106.8-130.1) versus 108.0 (102.3-115.2) pM, respectively, p all < 0.001). The mortality was 26% (11/43) in the PAH subgroup during a long-term follow-up of 42 (IQR: 32-58) months. Kaplan-Meier analysis showed that, in the PAH subgroup, patients with melatonin levels in the 1st quartile (<109.3 pM) had a worse survival than those in quartile 2-4 (Mean survival times were 46 (95% CI: 30-65) versus 68 (58-77) months, Log-rank, p = 0.026) with an increased hazard ratio of 3.5 (95% CI: 1.1-11.6, p = 0.038). Endogenous melatonin was increased in treatment-naïve patients with PH, and lower levels of melatonin were associated with worse long-term survival in patient with PAH.

Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: An Immunological Perspective.

Pulmonary hypertension (PH) is a debilitating progressive disease characterized by increased pulmonary arterial pressures, leading to right ventricular (RV) failure, heart failure and, eventually, death. Based on the underlying conditions, PH patients can be subdivided into the following five groups: (1) pulmonary arterial hypertension (PAH), (2) PH due to left heart disease, (3) PH due to lung disease, (4) chronic thromboembolic PH (CTEPH), and (5) PH with unclear and/or multifactorial mechanisms. Currently, even with PAH-specific drug treatment, prognosis for PAH and CTEPH patients remains poor, with mean five-year survival rates of 57%-59% and 53%-69% for PAH and inoperable CTEPH, respectively. Therefore, more insight into the pathogenesis of PAH and CTEPH is highly needed, so that new therapeutic strategies can be developed. Recent studies have shown increased presence and activation of innate and adaptive immune cells in both PAH and CTEPH patients. Moreover, extensive biomarker research revealed that many inflammatory and immune markers correlate with the hemodynamics and/or prognosis of PAH and CTEPH patients. Increased evidence of the pathological role of immune cells in innate and adaptive immunity has led to many promising pre-clinical interventional studies which, in turn, are leading to innovative clinical trials which are currently being performed. A combination of immunomodulatory therapies might be required besides current treatment based on vasodilatation alone, to establish an effective treatment and prevention of progression for this disease. In this review, we describe the recent progress on our understanding of the involvement of the individual cell types of the immune system in PH. We summarize the accumulating body of evidence for inflammation and immunity in the pathogenesis of PH, as well as the use of inflammatory biomarkers and immunomodulatory therapy in PAH and CTEPH.

Growth differentiation factor-15 as candidate predictor for mortality in adults with pulmonary hypertension.

OBJECTIVE: Despite its predictive value for mortality in various diseases, the relevance of growth differentiation factor-15 (GDF-15) as prognostic biomarker in pulmonary hypertension (PH) remains unclear. This study investigated the association between GDF-15 and outcomes in adults with PH. METHODS: This is a single-centre prospective observational cohort study. All adults with PH were included at the day of their diagnostic right heart catheterisation between 2012 and 2016. PH due to left heart disease was excluded. Venous blood sampling was performed and included GDF-15 and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements. Kaplan-Meier curves and Cox regression analysis were used to investigate the association between GDF-15 and a composite endpoint of death or lung transplantation. We adjusted for age and NT-proBNP in multivariable analysis. Reference values were established by GDF-15 measurements in healthy controls. RESULTS: GDF-15 was measured in 103 patients (median age 59.2 years, 65% women, 51% pulmonary arterial hypertension). GDF-15 was elevated in 76 patients (74%). After a median follow-up of 3.4 (IQR 2.3-4.6) years, 32 patients (31.1%) reached the primary endpoint. Event-free survival 2 years after diagnosis was 100% in patients with normal GDF-15 versus 72.4% in patients with elevated GDF-15 (p=0.007). A significant association was found between GDF-15 and the primary endpoint (HR per twofold higher value 1.77, 95% CI 1.39 to 2.27, p<0.001), also after adjustment for age and NT-proBNP (HR 1.41, 95% CI 1.02 to 1.94, p=0.038). CONCLUSIONS: High GDF-15 levels are associated with an increased risk of death or transplant in adults with PH, independent of age and NT-proBNP. As non-specific biomarker, GDF-15 could particularly be useful to detect low-risk patients.

The Prognostic Value of Soluble ST2 in Adults with Pulmonary Hypertension.

Soluble ST2 (sST2) is upregulated in response to myocardial stress and may serve as biomarker in adults with pulmonary hypertension (PH). This prospective cohort study investigated sST2 levels and its association with echocardiographic and hemodynamic measures, and adverse clinical outcomes in adults with PH of different etiologies. sST2 was measured during the diagnostic right heart catheterization for PH, in adult patients enrolled between May 2012 and October 2016. PH due to left heart failure was excluded. The association between sST2 and a primary endpoint composed of death or lung transplantation and a secondary composite endpoint including death, lung transplantation or heart failure, was investigated using Cox regression with adjustment for NT-proBNP. In total 104 patients were included (median age was 59 years, 66% woman, 51% pulmonary arterial hypertension). Median sST2 was 28 [IQR 20-46] ng/mL. Higher sST2 was associated with worse right ventricular dysfunction and higher mean pulmonary and right atrial pressures. Median follow-up was 3.3 [IQR 2.3-4.6] years. The primary and secondary endpoint occurred in 33 (31.7%) and 43 (41.3%) patients, respectively. sST2 was significantly associated with both endpoints (HR per 2-fold higher value 1.53, 95%CI 1.12-2.07, p = 0.007 and 1.45, 95%CI 1.10-1.90, p = 0.008, respectively). However, after adjustment for NT-proBNP, both associations did not reach statistical significance. In conclusions, higher sST2 levels are associated with more severe PH and right ventricular dysfunction and yields prognostic value in adults with PH, although not independently of NT-proBNP.