The impact of high-density lipoprotein (HDL) cholesterol on the development of atherosclerosis and diseases of systemic circulation has been well documented both in experimental and registry studies. Recent discoveries in pulmonary arterial hypertension (PAH) revealed a significant impact of HDL on pulmonary artery vasoreactivity and patients’ prognosis. The vasoprotective activity of HDL primarily involves vascular endothelium that also plays a central role in pulmonary arterial hypertension (PAH) pathobiology. However, the exact mechanism in which this lipoprotein fraction exerts its effect in pulmonary circulation is still under investigation. This paper reviews potential vasoprotective mechanisms of HDL in pulmonary circulation and presents current clinical reports on the role of HDL in PAH patients.

Pulmonary arterial hypertension (PAH) is a complex disorder characterized by increased pressure in the pulmonary arteries, leading to right heart failure. While the exact mechanisms underlying PAH are not fully understood, cytokines have been implicated in the pathogenesis of the disease. Cytokines play a crucial role in regulating immune responses and inflammation. These small proteins also play a key role in shaping the immunophenotype, which refers to the specific characteristics and functional properties of immune cells, which can have a significant impact on the development of PAH. The aim of this study was to determine the immunophenotype and the concentration of selected cytokines, IL-2, IL-4, IL-6, IL-10, and IFN-gamma, in patients diagnosed with PAH (with particular emphasis on subtypes) in relation to healthy volunteers. Based on the obtained results, we can conclude that in patients with PAH, the functioning of the immune system is deregulated as a result of a decrease in the percentage of selected subpopulations of immune cells in peripheral blood and changes in the concentration of tested cytokines in relation to healthy volunteers. In addition, a detailed analysis showed that there are statistically significant differences between the PAH subtypes and the tested immunological parameters. This may indicate a significant role of the immune system in the pathogenesis of PAH.

Background: Inflammatory response and endothelial dysfunction contribute to the progression of chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to assess changes in biomarkers involved in those processes in inoperable CTEPH patients treated with balloon pulmonary angioplasty (BPA). Methods: We enrolled 20 patients with inoperable CTEPH qualified for BPA and a control group. Interleukin 6, 8, 10 (IL-6, IL-8, IL-10), monocyte chemoattractant protein-1 (MCP-1), and C-reactive protein (hsCRP) constituted the markers of systemic inflammation. Endothelin 1 (ET-1) served as a marker of endothelial dysfunction. Selected markers were assessed before the BPA treatment, 24 h after the first BPA, and six months after completion of the BPA treatment. Results: At baseline, the CTEPH patients had increased serum concentrations of IL-6, IL-8 and ET-1. Twenty-four hours after a BPA session, we observed an increase in concentrations of IL-6 (∆ = 3.67 (1.41; 7.16); p < 0.001), of IL-10 (∆ = 0.25 (0; 0.47); p = 0.003), of MCP-1 (∆ = 111 (60.1; 202.8); p = 0.002), and of hsCRP (∆ = 4.81 (3.46; 8.47); p < 0.001). Six months after completion of the BPA treatment, there was a decrease in concentrations of IL-6 (∆ = −1.61 (−3.11; −0.20); p = 0.03), of IL8 (∆ = −3.24 (−7.72; 0.82); p = 0.01), and of ET-1 (∆ = −0.47 (−0.96; 0.05); p = 0.005). Conclusions: Patients with inoperable CTEPH exhibit increased systemic inflammation and endothelial dysfunction, which improves after completion of the BPA treatment. A single BPA session evokes an acute inflammatory response.

Chronic thromboembolic pulmonary hypertension (CTEPH) results from an obstruction of pulmonary arteries (PAs) by organized thrombi. The stenosed PAs are targeted during balloon pulmonary angioplasty (BPA). We aimed to evaluate the mechanism of BPA in inoperable patients with CTEPH. We analyzed stenosed PAs with intravascular grey-scale ultrasound (IVUS) to determine the cross-sectional area (CSA) of arterial lumen and of organized thrombi. The composition of organized thrombi was assessed using virtual histology. We distinguished two mechanisms of BPA: Type A with dominant vessel stretching, and type B with dominant thrombus compression. PAs were assessed before (n = 159) and after (n = 98) BPA in 20 consecutive patients. Organized thrombi were composed of dark-green (57.1 (48.0–64.0)%), light-green (34.0 (21.4–46.4)%), red (6.4 (2.9–11.7)%;) and white (0.2 (0.0–0.9)%) components. The mechanism type depended on vessel diameter (OR = 1.09(1.01–1.17); p = 0.03). In type B mechanism, decrease in the amount of light-green component positively correlated with an increase in lumen area after BPA (r = 0.50; p = 0.001). The mechanism of BPA depends on the diameter of the vessel. Dilation of more proximal PAs depends mainly on stretching of the vessel wall while dilation of smaller PAs depends on compression of the organized thrombi. The composition of the organized thrombi contributes to the effect of BPA.

Pulmonary arterial hypertension (PAH) is a rare disease with a serious prognosis. The aim of this study was to identify biomarkers for PAH in the breath phase and to prepare an automatic classification method to determine the changing metabolome trends and molecular mapping. A group of 37 patients (F/M: 8/29 women, mean age 60.4 ± 10.9 years, BMI 27.6 ± 6.0 kg/m²) with diagnosed PAH were enrolled in the study. The breath phase of all the patients was collected on a highly porous septic material using a special patented holder PL230578, OHIM 002890789-0001. The collected air was then examined with gas chromatography coupled with mass spectrometry (GC/MS). The algorithms of Spectral Clustering, KMeans, DBSCAN, and hierarchical clustering methods were used to perform the cluster analysis. The identification of the changes in the ratio of the whole spectra of biomarkers allowed us to obtain a multidimensional pathway for PAH characteristics and showed the metabolome differences in the four subgroups divided by the cluster analysis. The use of GC/MS, supported with novel porous polymeric materials, for the breath phase analysis seems to be a useful tool in selecting bio-fingerprints in patients with PAH. The four metabolome classes which were obtained constitute novel data in the PAH population.

Introduction: Pulmonary arterial hypertension (PAH) is a rare, severe disorder of multifactorial origin. Genetic alterations in BMP/SMAD pathways were previously associated with disease development, however the exact role of other genetic factors from BMP/SMAD signalling is still unclear. Purpose: We aimed to search for known PAH-associated mutations and potential novel variants responsible for disease onset in Polish PAH patients. Methods: We prospectively recruited 93 consecutive idiopathic PAH patients from a single pulmonary hypertension reference centre between years 2009 and 2020. Eligible patients had pre-capillary pulmonary hypertension with pulmonary vascular resistance >3 Wood units in the absence of other causes of pre-capillary pulmonary hypertension. The presence of large gene rearrangements was analyzed by the Multiplex Ligation-dependent Probe Amplification (MLPA) reactions in the ENG, ACVRL1 and BMPR2 genes (SALSA MLPA Kit, MRC-Holland). We have further sequenced a panel of selected 48 genes from BMP/SMAD and related pathways using next-generation sequencing (SureSelect XT library preparation Kit, Agilent; NextSeq 500 sequencer, Illumina) and assessed causative potential of rare variants (minor allele frequency in non-finish Europeans below 1%) with Mutation Taster web-based tool. Results: We identified at least one likely-causative variant of investigated genes in 51 (54.8%) subjects. Large genomic rearrangements were found by MLPA in 2 patients in ENG and ACVRL1 (ALK1) genes. We have found mutations in BMPR2 gene in 12 patients (12.5%) from our cohort with most variants present in one sample and 3 variants present in 2 samples. Mutations were located mostly in protein kinase domain (6 variants) and Activin type I and II receptor domain (2 variants). We have found 5 likely pathogenic variants in 6 patients in genes previously associated with PAH other than BMPR2 (SMAD9, KCNA5, KCNK3, EIF2AK4). In total, potentially disease causing mutations in literature-known genes, were present in 18 patients, which accounted for 18.75% of tested cohort. Medium impact variants were also present in KCNA5, TGFBR2, AQP7, BMP6, EIF2AK4, FBP1, NOTCH1, NOTCH3, SMAD7, TBX4, TGFB2, TOPBP1, GDF5, IL6, PPARA, RXRA, KCNK3, KLF4, BMPR1B, ILK, TGFBR1, SMAD9, PPARD and TGFB3 genes. Additionally, in one patient with clinical diagnosis of pulmonary venoocclusive disease we identified an unknown homozygous frameshift variant (p.Phe1523fs/c.4567_4570delTTTG) in exon 35 of EIF2AK4 gene. Conclusions: We found potentially disease causing mutations in 18,75% Polish patients diagnosed with IPAH most of them were present in BMPR2 gene which is in line with data from other European cohorts. Additionally we found an unknown mutation in the EIF2AK4 gene. Funding Acknowledgement: Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Narodowe Centrum Nauki - National Science Centre