Novel Liver Injury Phenotypes and Outcomes in Clinical Trial Participants with Pulmonary Hypertension.

RATIONALE: Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) cause right ventricular dysfunction which can impact other solid organs. However, the profiles and consequences of hepatic injury due to PAH and CTEPH have not been well-studied. OBJECTIVES: We aimed to identify underlying patterns of liver injury in a cohort of PAH and CTEPH patients enrolled in 15 randomized clinical trials conducted between 1998 and 2014. METHODS: We used unsupervised machine learning to identify liver injury clusters in 13 trials and validated the findings in two additional trials. We then determined whether these liver injury clusters were associated with clinical outcomes or treatment effect heterogeneity. MEASUREMENTS AND MAIN RESULTS: Our training dataset included 4,219 patients and our validation dataset included 1,756 patients with serum total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and albumin data. Using k-means clustering, we identified phenotypes with no liver injury, hepatocellular injury, cholestatic injury, and combined injury patterns. Patients in the cholestatic injury liver cluster had the shortest time to clinical worsening and the highest risk of mortality. The cholestatic injury group also experienced the greatest placebo-corrected treatment effect on six-minute walk distance. Randomization to the experimental arm transitioned patients to a healthier liver status. CONCLUSIONS: Liver injury was associated with adverse outcomes in patients with PAH and CTEPH. Randomization to active treatment had beneficial effects on liver health compared to placebo. The role of liver disease (often subclinical) in determining outcomes warrants prospective studies.

Novel Liver Injury Phenotypes and Outcomes in Pulmonary Arterial Hypertension.

Background: Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are disorders of the pulmonary vasculature that cause right ventricular dysfunction. Systemic consequences of right ventricular dysfunction include damage to other solid organs, such as the liver. However, the profiles and consequences of hepatic injury due to PAH and CTEPH have not been well-studied. Methods: We aimed to identify underlying patterns of liver injury in a cohort of PAH and CTEPH patients enrolled in 15 randomized clinical trials conducted between 1998 and 2012. We used unsupervised machine learning to identify liver injury clusters in 13 trials and validated the findings in two additional trials. We then determined whether these liver injury clusters were associated with clinical outcomes or treatment effect heterogeneity. Results: Our training dataset included 4,219 patients and our validation dataset included 1,756 patients with complete liver laboratory panels (serum total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and albumin). Using k-means clustering paired with factor analysis, we identified four unique liver phenotypes (no liver injury, hepatocellular injury, cholestatic injury, and combined injury patterns). Patients in the cholestatic injury liver cluster had the shortest time to clinical worsening and highest chance of worsening World Health Organization functional class. Randomization to the experimental arm was associated with a transition to healthier liver clusters compared to randomization to the control arm. The cholestatic injury group experienced the greatest placebo-corrected treatment benefit in terms of six-minute walk distance. Conclusions: Liver injury patterns were associated with adverse outcomes in patients with PAH and CTEPH. Randomization to active treatment of pulmonary hypertension in these clinical trials had beneficial effects on liver health compared to placebo. The independent role of liver disease (often subclinical) in determining outcomes warrants prospective studies of the clinical utility of liver phenotyping for PAH prognosis and contribution to clinical disease.

Distinct plasma gradients of microRNA-204 in the pulmonary circulation of patients suffering from WHO Groups I and II pulmonary hypertension.

Pulmonary hypertension (PH), a heterogeneous vascular disease, consists of subtypes with overlapping clinical phenotypes. MicroRNAs, small non-coding RNAs that negatively regulate gene expression, have emerged as regulators of PH pathogenesis. The muscle-specific micro RNA (miR)-204 is known to be depleted in diseased pulmonary artery smooth muscle cells (PASMCs), furthering proliferation and promoting PH. Alterations of circulating plasma miR-204 across the trans-pulmonary vascular bed might provide mechanistic insights into the observed intracellular depletion and may help distinguish PH subtypes. MiR-204 levels were quantified at sequential pulmonary vasculature sites in 91 patients with World Health Organization (WHO) Group I pulmonary arterial hypertension (PAH) (n = 47), Group II PH (n = 22), or no PH (n = 22). Blood from the right atrium/superior vena cava, pulmonary artery, and pulmonary capillary wedge was collected. Peripheral blood mononuclear cells (PBMCs) were isolated (n = 5/group). Excretion of miR-204 by PAH-PASMCs was also quantified in vitro. In Group I patients only, miR-204 concentration increased sequentially along the pulmonary vasculature (log fold-change slope = 0.22 [95% CI = 0.06-0.37], P = 0.008). PBMCs revealed insignificant miR-204 variations among PH groups ( P = 0.12). Cultured PAH-PAMSCs displayed a decrease of intracellular miR-204 ( P = 0.0004), and a converse increase of extracellular miR-204 ( P = 0.0018) versus control. The stepwise elevation of circulating miR-204 across the pulmonary vasculature in Group I, but not Group II, PH indicates differences in muscle-specific pathobiology between subtypes. Considering the known importance of miR-204 in PH, these findings may suggest pathologic excretion of miR-204 in Group I PAH by PASMCs, thereby accounting for decreased intracellular miR-204 concentration.

Risk factors for intracranial haemorrhage in patients with pulmonary embolism treated with thrombolytic therapy Development of the PE-CH Score.

Pulmonary embolism (PE) is a major cause of morbidity and mortality world-wide, and the use of thrombolytic therapy has been associated with favourable clinical outcomes in certain patient subsets. These potential benefits are counterbalanced by the risk of bleeding complications, the most devastating of which is intracranial haemorrhage (ICH). We retrospectively evaluated 9703 patients from the 2003-2012 nationwide in-patient sample database (NIS) who received thrombolytics for PE. All patients with ICH during the PE hospitalisation were identified and a clinical risk score model was developed utilizing demographics and comorbidities. The dataset was divided 1:1 into derivation and validation cohorts. During 2003-2012, 176/9705 (1.8 %) patients with PE experienced ICH after thrombolytic use. Four independent prognostic factors were identified in a backward logistic regression model, and each was assigned a number of points proportional to its regression coefficient: pre-existing Peripheral vascular disease (1 point), age greater than 65 years (Elderly) (1 point), prior Cerebrovascular accident with residual deficit (5 points), and prior myocardial infarction (Heart attack) (1 point). In the derivation cohort, scores of 0, 1, 2 and ≥ 5 points were associated with ICH risks of 1.2 %, 1.9 %, 2.4 % and 17.8 %, respectively. Rates of ICH were similar in the validation cohort. The C-statistic for the risk score was 0.65 (0.61-0.70) in the derivation cohort and 0.66 (0.60-0.72) in the validation cohort. A novel risk score, derived from simple clinical historical elements was developed to predict ICH in PE patients treated with thrombolytics.

Autophagic protein LC3B confers resistance against hypoxia-induced pulmonary hypertension.

RATIONALE: Pulmonary hypertension (PH) is a progressive disease with unclear etiology. The significance of autophagy in PH remains unknown. OBJECTIVES: To determine the mechanisms by which autophagic proteins regulate tissue responses during PH. METHODS: Lungs from patients with PH, lungs from mice exposed to chronic hypoxia, and human pulmonary vascular cells were examined for autophagy using electron microscopy and Western analysis. Mice deficient in microtubule-associated protein-1 light chain-3B (LC3B(-/-)), or early growth response-1 (Egr-1(-/-)), were evaluated for vascular morphology and hemodynamics. MEASUREMENTS AND MAIN RESULTS: Human PH lungs displayed elevated lipid-conjugated LC3B, and autophagosomes relative to normal lungs. These autophagic markers increased in hypoxic mice, and in human pulmonary vascular cells exposed to hypoxia. Egr-1, which regulates LC3B expression, was elevated in PH, and increased by hypoxia in vivo and in vitro. LC3B(-/-) or Egr-1(-/-), but not Beclin 1(+/-), mice displayed exaggerated PH during hypoxia. In vitro, LC3B knockdown increased reactive oxygen species production, hypoxia-inducible factor-1α stabilization, and hypoxic cell proliferation. LC3B and Egr-1 localized to caveolae, associated with caveolin-1, and trafficked to the cytosol during hypoxia. CONCLUSIONS: The results demonstrate elevated LC3B in the lungs of humans with PH, and of mice with hypoxic PH. The increased susceptibility of LC3B(-/-) and Egr-1(-/-) mice to hypoxia-induced PH and increased hypoxic proliferation of LC3B knockdown cells suggest adaptive functions of these proteins during hypoxic vascular remodeling. The results suggest that autophagic protein LC3B exerts a protective function during the pathogenesis of PH, through the regulation of hypoxic cell proliferation.

Autophagy in vascular disease.

Autophagy, or "self eating," refers to a regulated cellular process for the lysosomal-dependent turnover of organelles and proteins. During starvation or nutrient deficiency, autophagy promotes survival through the replenishment of metabolic precursors derived from the degradation of endogenous cellular components. Autophagy represents a general homeostatic and inducible adaptive response to environmental stress, including endoplasmic reticulum stress, hypoxia, oxidative stress, and exposure to pharmaceuticals and xenobiotics. Whereas elevated autophagy can be observed in dying cells, the functional relationships between autophagy and programmed cell death pathways remain incompletely understood. Preclinical studies have identified autophagy as a process that can be activated during vascular disorders, including ischemia-reperfusion injury of the heart and other organs, cardiomyopathy, myocardial injury, and atherosclerosis. The functional significance of autophagy in human cardiovascular disease pathogenesis remains incompletely understood, and potentially involves both adaptive and maladaptive outcomes, depending on model system. Although relatively few studies have been performed in the lung, our recent studies also implicate a role for autophagy in chronic lung disease. Manipulation of the signaling pathways that regulate autophagy could potentially provide a novel therapeutic strategy in the prevention or treatment of human disease.