Rationale: Normal mean pulmonary arterial pressure (mPAP) is 14.0 ± 3.3 mm Hg (mean ± SD). The prognostic relevance of mildly elevated mPAP not fulfilling the definition of pulmonary hypertension (PH; mPAP ≥ 25 mm Hg) has not been prospectively evaluated in a real-world setting. Objectives: To assess the association of resting mPAP with all-cause mortality in a retrospective and a prospective cohort of patients with unexplained dyspnea and/or at risk of PH. Methods: Prognostic cutoffs were calculated by means of 1) classification and regression tree (CART) analysis without any preset thresholds, and 2) preset thresholds on the basis of literature data defining mPAP as lower-normal (≤mean + 1 SD), upper-normal (between mean + 1 SD and mean + 2 SD), borderline (between mean + 2 SD and 25 mm Hg), and manifest PH (≥25 mm Hg). We performed univariate and multivariate survival analysis adjusted for age and comorbidities. Measurements and Main Results: We enrolled 547 patients, of whom 137, 56, 64, and 290 presented with lower-normal, upper-normal, or borderline mPAP, and manifest PH, respectively. The CART analysis on mPAP discriminated three prognostic groups: mPAP less than 17 mm Hg, 17 to 26 mm Hg, and greater than 26 mm Hg, with significantly decreasing survival. The univariate analysis on the basis of preset thresholds showed that upper-normal mPAP, borderline mPAP, and manifest PH were significantly associated with poor survival compared with lower-normal mPAP. In the multivariate model, considering age and comorbidities, only borderline mPAP (hazard ratio, 2.37; 95% confidence interval, 1.14–4.97; P = 0.022) and manifest PH (hazard ratio, 5.05; 95% confidence interval, 2.79–9.12; P < 0.001) were significantly associated with poor survival. Conclusions: In patients at risk for PH and/or with unexplained dyspnea, CART analysis detects prognostic thresholds at a resting mPAP of 17 mm Hg and 26 mm Hg, and values between 20 mm Hg and 25 mm Hg represent an independent predictor of poor survival. Clinical trial registered with www.clinicaltrials.gov (NCT 01607502).

Background: Biomarkers for predicting response to immune checkpoint inhibitors (ICI) are scarce and often lack external validation. This study provides a comprehensive investigation of pretreatment C-reactive protein (CRP) levels as well as its longitudinal trajectories as a marker of treatment response and disease outcome in patients with advanced non-small cell lung cancer (NSCLC) undergoing immunotherapy with anti PD-1 or anti PD-L1 agents. Methods: We performed a retrospective bi-center study to assess the association between baseline CRP levels and anti PD-(L)1 treatment outcomes in the discovery cohort (n = 90), confirm these findings in an external validation cohort (n = 101) and explore the longitudinal evolution of CRP during anti PD-(L)1 treatment and the potential impact of dynamic CRP changes on treatment response and disease outcome in the discovery cohort. Joint models were implemented to evaluate the association of longitudinal CRP trajectories and progression risk. Primary treatment outcomes were progression-free survival (PFS) and overall survival (OS), while the objective response rate (ORR) was a secondary outcome, respectively. Results: In the discovery cohort, elevated pretreatment CRP levels emerged as independent predictors of worse PFS (HR per doubling of baseline CRP = 1.37, 95% CI: 1.16–1.63, p < 0.0001), worse OS (HR per doubling of baseline CRP = 1.42, 95% CI: 1.18–1.71, p < 0.0001) and a lower ORR ((odds ratio (OR) of ORR per doubling of baseline CRP = 0.68, 95% CI: 0.51–0.92, p = 0.013)). In the validation cohort, pretreatment CRP could be fully confirmed as a predictor of PFS and OS, but not ORR. Elevated trajectories of CRP during anti PD-(L)1 treatment (adjusted HR per 10 mg/L increase in CRP = 1.22, 95% CI: 1.15–1.30, p < 0.0001), as well as a faster increases of CRP over time (HR per 10 mg/L/month faster increase in CRP levels = 13.26, 95% CI: 1.14–154.54, p = 0.039) were strong predictors of an elevated progression risk, whereas an early decline of CRP was significantly associated with a reduction in PFS risk (HR = 0.91, 95% CI: 0.83–0.99, p = 0.036), respectively. Conclusion: These findings support the concept that CRP should be further explored by future prospective studies as a simple non-invasive biomarker for assessing treatment benefit during anti PD-(L)1 treatment in advanced NSCLC.

In patients with end-stage chronic obstructive pulmonary disease (COPD), severe pulmonary hypertension (PH) is frequently associated with less severe airway obstruction as compared to mild or no PH. However, the histologic correlate of this finding is not clear. We aimed to quantify remodeling of pulmonary arteries, airways, and parenchyma in random samples of explanted end-stage COPD lungs. We quantified remodeling of small pulmonary arteries, small airways, and the degree of emphysema (mean interseptal distance [MID]) with dedicated software. As primary objective, we compared COPD patients with severe PH (SevPH-COPD) with age- and sex-matched MildPH-COPD. For comparison, we also investigated COPD lungs with no PH (NoPH-COPD), idiopathic PAH (IPAH), and healthy donors. We included n = 17 SevPH-COPD (mPAP = 43 [39-45]mm Hg), n = 17 MildPH-COPD (mPAP = 28 [24-31]mm Hg), n = 5 NoPH-COPD (mPAP = 18 [16-19]mm Hg), n = 10 IPAH (mPAP = 72 [65-91]mm Hg), and n = 10 healthy donor lungs. SevPH-COPD versus MildPH-COPD was characterized by better preserved forced vital capacity (51% vs 40% predicted, p < 0.05), less emphysema (MID 169 µm vs 279 µm, p < 0.001), and less PAS-positive and CD45-positive mucosa cells (15% vs 22%, p = 0.063% and 5% vs 7%, p = 0.058) suggesting less airway inflammation. In COPD patients, intimal and medial thickening were strongly correlated with mPAP (r = 0.676, p < 0.001 and r = 0.595, p < 0.001). MID was negatively correlated with mPAP (r = -0.556, p < 0.001) and was highest in NoPH-COPD (mean 281 µm), suggesting that emphysema per se is not associated with PH. End-stage COPD with severe PH is characterized by pronounced pulmonary vascular remodeling, less inflammation of small airways, and less emphysema as compared to COPD with mild PH or no PH, suggesting that COPD with severe PH may represent a unique phenotype of COPD.

Background: The gut–lung axis could be a potential therapeutic target for improving post-acute COVID-19 symptoms, and probiotics have been proposed as possible modulators. Aim: We conducted a pilot study to understand alterations in the gut–lung axis and to explore the effects of a probiotic in post-acute COVID-19 disease. Methods: We included patients after severe COVID-19 disease (sCOV, n = 21) in a randomized, placebo-controlled trial to test the effect of a probiotic (Pro-Vi 5, Institute Allergosan, Graz, Austria) in a six-month intervention and used patients after mild disease (mCOV, n = 10) as controls, to compare the intestinal microbiome, metabolome, and patient-reported outcomes and biomarkers along the gut–lung axis at baseline and throughout probiotic intervention. Results: Compared to mCOV patients, sCOV patients showed lower microbial richness, which was significantly improved by probiotic intervention. A reorganization of Ruminococcaceae and Lachnospiraceae taxa was observed in sCOV patients but remained unaffected by the intervention. Serum metabolome showed a dysregulation of lipoproteins in accordance with higher BMI and comorbidities in sCOV patients. HDL and LDL fractions/components were temporarily decreased in the probiotic group. Stool metabolome was altered at baseline in sCOV patients and an increase in L-DOPA after 3 months and butyrate after 6 months of intervention could be observed. Probiotics partially improved reduced quality of life and modulated altered immune responses in sCOV patients. Increased intestinal permeability at baseline remained unaffected. Conclusion: The study provides evidence of long-term alterations of the gut–lung axis after severe COVID-19 infection and suggests that probiotics can modulate the biomarkers of the gut–lung axis.

Rationale: Pulmonary hypertension (PH) poses a significant health threat. Current biomarkers for PH lack specificity and have poor prognostic capabilities. Objectives: To develop better biomarkers for PH that are useful for patient identification and management. Methods: An explorative analysis was conducted of a broad spectrum of metabolites in patients with PH, healthy control subjects, and diseased control subjects in training and validation cohorts, together with in vitro studies on human pulmonary arteries. Measurements and Main Results: High-resolution mass spectrometry was performed in 233 subjects coupled with machine learning analysis. Histologic and gene expression analysis was conducted, with a focus on lipid metabolism in human pulmonary arteries of idiopathic pulmonary arterial hypertension lungs and assessment of the acute effects of extrinsic fatty acids (FAs). We enrolled a training cohort of 74 patients with PH, 30 diseased control subjects without PH, and 65 healthy control subjects, as well as an independent validation cohort of 64 subjects. Among other metabolites, FAs were significantly increased. Machine learning showed a high diagnostic potential for PH. In addition, we developed fully explainable lipid ratios with exceptional diagnostic accuracy for PH (areas under the curve of 0.89 in the training cohort and 0.90 in the external validation cohort), outperforming machine learning results. These ratios were also prognostic and complemented established clinical markers and scores, significantly increasing their hazard ratios for mortality risk. Idiopathic pulmonary arterial hypertension lungs showed lipid accumulation and altered expression of lipid homeostasis–related genes. In human pulmonary artery smooth muscle and endothelial cells, FAs caused excessive proliferation and barrier dysfunction, respectively. Conclusions: Our metabolomics approach suggests that lipid alterations in PH provide diagnostic and prognostic information, complementing established markers. These alterations may reflect pathologic changes in the pulmonary arteries of patients with PH.

Idiopathic pulmonary arterial hypertension (IPAH) pulmonary arteries (PAs) displayed the greatest proteoglycan (PG) changes, with PH associated with pulmonary fibrosis (PH-PF) and PH associated with chronic obstructive pulmonary disease (PH-COPD) following. Agrin, an endothelial cell-specific PG, was solely upregulated in IPAH. Among all cells, neo-intima-forming smooth muscle cells (SMCs) displayed the most significant PG increase. Increased levels of circulating decorin, lumican, and versican, mainly derived from SMCs, and adventitial fibroblasts, may serve as systemic indicators of pulmonary remodeling, reflecting perivascular fibrosis and neointima formation.