Pathophysiology and Treatment of Chronic Thromboembolic Pulmonary Hypertension

The significance of CD16+ monocytes in the occurrence and development of chronic thromboembolic pulmonary hypertension: insights from single-cell RNA sequencing

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious pulmonary vascular disease characterized by residual thrombi in the pulmonary arteries and distal pulmonary microvascular remodeling. The pathogenesis of CTEPH remains unclear, but many factors such as inflammation, immunity, coagulation and angiogenesis may be involved. Monocytes are important immune cells that can differentiate into macrophages and dendritic cells and play an important role in thrombus formation. However, the distribution, gene expression profile and differentiation trajectory of monocyte subsets in CTEPH patients have not been systematically studied. This study aims to reveal the characteristics and functions of monocytes in CTEPH patients using single-cell sequencing technology, and to provide new insights for the diagnosis and treatment of CTEPH.

Methods

Single-cell RNA sequencing (scRNA-seq) were performed to analyze the transcriptomic features of peripheral blood mononuclear cells (PBMCs) from healthy controls, CTEPH patients and the tissues from CTEPH patients after the pulmonary endarterectomy (PEA). We established a CTEPH rat model with chronic pulmonary embolism caused by repeated injection of autologous thrombi through a central venous catheter, and used flow cytometry to detect the proportion changes of monocyte subsets in CTEPH patients and CTEPH rat model. We also observed the infiltration degree of macrophage subsets in thrombus tissue and their differentiation relationship with peripheral blood monocyte subsets by immunofluorescence staining.

Results

The results showed that the monocyte subsets in peripheral blood of CTEPH patients changed significantly, especially the proportion of CD16+ monocyte subset increased. This monocyte subset had unique functional features at the transcriptomic level, involving processes such as cell adhesion, T cell activation, coagulation response and platelet activation, which may play an important role in pulmonary artery thrombus formation and pulmonary artery intimal remodeling. In addition, we also found that the macrophage subsets in pulmonary endarterectomy tissue of CTEPH patients showed pro-inflammatory and lipid metabolism reprogramming features, which may be related to the persistence and insolubility of pulmonary artery thrombi and the development of pulmonary hypertension. Finally, we also observed that CD16+ monocyte subset in peripheral blood of CTEPH patients may be recruited to pulmonary artery intimal tissue and differentiate into macrophage subset with high expression of IL-1β, participating in disease progression.

Conclusion

CD16+ monocytes subset had significant gene expression changes in CTEPH patients, related to platelet activation, coagulation response and inflammatory response. And we also found that these cells could migrate to the thrombus and differentiate into macrophages with high expression of IL-1β involved in CTEPH disease progression. We believe that CD16+ monocytes are important participants in CTEPH and potential therapeutic targets.

Tissue factor regulates autophagy in pulmonary artery endothelial cells from chronic thromboembolic pulmonary hypertension rats via the p38 MAPK-FoxO1 pathway

AIMS

To detect the expression of autophagy components, p38 MAPK (p38) and phosphorylated forkhead box transcription factor O-1 (pFoxO1) in pulmonary vascular endothelial cells of chronic thromboembolic pulmonary hypertension (CTEPH) rats and to investigate the possible mechanism through which tissue factor (TF) regulates autophagy.

METHODS

Pulmonary artery endothelial cells (PAECs) were isolated from CTEPH (CTEPH group) and healthy rats (control group (ctrl group)) which were cocultured with TF at different time points including 12 h, 24 h, 48 h and doses including 0 nM,10 nM, 100 nM, 1µM, 10µM, 100µM and cocultured with TFPI at 48 h including 0 nM, 2.5 nM, 5 nM. The expression of forkhead box transcription factor O-1 (FoxO1), pFoxO1, p38, Beclin-1 and LC3B in PAECs was measured. Coimmunoprecipitation (co-IP) assays were used to detect the interaction between FoxO1 and LC3.

RESULTS

The protein expression of p-FoxO1/FoxO1 was significantly lower in the CTEPH groups (cocultured with TF from 0 nM to 100 µM) than in the ctrl group at 12 h, 24 h, and 48 h (P < 0.05) and was significantly lower in the CTEPH groups (cocultured with TFPI from 0 nM to 5 nM) than in the ctrl group at 48 h (P < 0.05). The protein expression of p38 in the CTEPH groups treated with 0 nM, 10 nM, 100 nM or 1 µM TF for 48 h significantly increased than ctrl groups (P < 0.05) and was significantly increased in the CTEPH groups (cocultured with TFPI concentration from 0 nM to 5 nM) than in the ctrl group at 48 h (P < 0.05). The protein expression of Beclin1 at the same concentration (cocultured with TF from 0 nM to 100 µM) was significantly lower in the CTEPH groups than ctrl groups after 24 h and 48 h (P < 0.05) and was significantly decreased in the CTEPH groups (cocultured with TFPI concentration from 2.5 nM to 5 nM) than in the ctrl group at 48 h (P < 0.05). The protein expression of LC3-II/LC3-I at the same concentration (cocultured with TF 0 nM, 1 µM, 10 µM, and 100 µM) was significantly lower in the CTEPH than in the ctrl groups after 12 h (P < 0.05) and was significantly lower in the CTEPH groups (cocultured with TFPI concentration from 0 nM to 5 nM) than in the ctrl group at 48 h (P < 0.05). There were close interactions between FoxO1 and LC3 in the control and CTEPH groups at different doses and time points.

CONCLUSION

The autophagic activity of PAECs from CTEPH rats was disrupted. TF, FoxO1 and p38 MAPK play key roles in the autophagic activity of PAECs. TF may regulate autophagic activity through the p38 MAPK-FoxO1 pathway.

Effects of right ventricular remodeling in chronic thromboembolic pulmonary hypertension on the outcomes of balloon pulmonary angioplasty: a 2D-speckle tracking echocardiography study

BACKGROUND

Balloon pulmonary angioplasty (BPA) improves the prognosis of chronic thromboembolic pulmonary hypertension (CTEPH). Right ventricle (RV) is an important predictor of prognosis in CTEPH patients. 2D-speckle tracking echocardiography (2D-STE) can evaluate RV function. This study aimed to evaluate the effectiveness of BPA in CTEPH patients and to assess the value of 2D-STE in predicting outcomes of BPA.

METHODS

A total of 76 patients with CTEPH underwent 354 BPA sessions from January 2017 to October 2022. Responders were defined as those with mean pulmonary artery pressure (mPAP) ≤ 30 mmHg or those showing ≥ 30% decrease in pulmonary vascular resistance (PVR) after the last BPA session, compared to baseline. Logistic regression analysis was performed to identify predictors of BPA efficacy.

RESULTS

BPA resulted in a significant decrease in mPAP (from 50.8 ± 10.4 mmHg to 35.5 ± 11.9 mmHg, p < 0.001), PVR (from 888.7 ± 363.5 dyn·s·cm-5 to 545.5 ± 383.8 dyn·s·cm-5, p < 0.001), and eccentricity index (from 1.3 to 1.1, p < 0.001), and a significant increase in RV free wall longitudinal strain (RVFWLS: from 15.7% to 21.0%, p < 0.001). Significant improvement was also observed in the 6-min walking distance (from 385.5 m to 454.5 m, p < 0.001). After adjusting for confounders, multivariate analysis showed that RVFWLS was the only independent predictor of BPA efficacy. The optimal RVFWLS cutoff value for predicting BPA responders was 12%.

CONCLUSIONS

BPA was found to reduce pulmonary artery pressure, reverse RV remodeling, and improve exercise capacity. RVFWLS obtained by 2D-STE was an independent predictor of BPA outcomes. Our study may provide a meaningful reference for interventional therapy of CTEPH.

Predominance of M2 macrophages in organized thrombi in chronic thromboembolic pulmonary hypertension patients

Chronic thromboembolic pulmonary hypertension (CTEPH) is a debilitating disease characterized by thrombotic occlusion of pulmonary arteries and vasculopathy, leading to increased pulmonary vascular resistance and progressive right-sided heart failure. Thrombotic lesions in CTEPH contain CD68+ macrophages, and increasing evidence supports their role in disease pathogenesis. Macrophages are classically divided into pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages, which are involved in wound healing and tissue repair. Currently, the phenotype of macrophages and their localization within thrombotic lesions of CTEPH are largely unknown. In our study, we subclassified thrombotic lesions of CTEPH patients into developing fresh thrombi (FT) and organized thrombi (OT), based on the degree of fibrosis and remodeling. We used multiplex immunofluorescence histology to identify immune cell infiltrates in thrombotic lesions of CPTEH patients. Utilizing software-assisted cell detection and quantification, increased proportions of macrophages were observed in immune cell infiltrates of OT lesions, compared with FT. Strikingly, the proportions with a CD206+INOS- M2 phenotype were significantly higher in OT than in FT, which mainly contained unpolarized macrophages. Taken together, we observed a shift from unpolarized macrophages in FT toward an expanded population of M2 macrophages in OT, indicating a dynamic role of macrophages during CTEPH pathogenesis.

Analysis of genes characterizing chronic thrombosis and associated pathways in chronic thromboembolic pulmonary hypertension

PURPOSE

In chronic thromboembolic pulmonary hypertension (CTEPH), fibrosis of thrombi in the lumen of blood vessels and obstruction of blood vessels are important factors in the progression of the disease. Therefore, it is important to explore the key genes that lead to chronic thrombosis in order to understand the development of CTEPH, and at the same time, it is beneficial to provide new directions for early identification, disease prevention, clinical diagnosis and treatment, and development of novel therapeutic agents.

METHODS

The GSE130391 dataset was downloaded from the Gene Expression Omnibus (GEO) public database, which includes the full gene expression profiles of patients with CTEPH and Idiopathic Pulmonary Arterial Hypertension (IPAH). Differentially Expressed Genes (DEGs) of CTEPH and IPAH were screened, and then Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) functional enrichment analyses were performed on the DEGs; Weighted Gene Co-Expression Network Analysis (WGCNA) to screen the key gene modules and take the intersection genes of DEGs and the key module genes in WGCNA; STRING database was used to construct the protein-protein interaction (PPI) network; and cytoHubba analysis was performed to identify the hub genes.

RESULTS

A total of 924 DEGs were screened, and the MEturquoise module with the strongest correlation was selected to take the intersection with DEGs A total of 757 intersecting genes were screened. The top ten hub genes were analyzed by cytoHubba: IL-1B, CXCL8, CCL22, CCL5, CCL20, TNF, IL-12B, JUN, EP300, and CCL4.

CONCLUSION

IL-1B, CXCL8, CCL22, CCL5, CCL20, TNF, IL-12B, JUN, EP300, and CCL4 have diagnostic and therapeutic value in CTEPH disease, especially playing a role in chronic thrombosis. The discovery of NF-κB, AP-1 transcription factors, and TNF signaling pathway through pivotal genes may be involved in the disease progression process.

Clinical outcomes between direct oral anticoagulants versus vitamin K antagonists in chronic thromboembolic pulmonary hypertension: A systematic review and meta-analysis

Pulmonary hypertension (PH) is a known chronic condition that can lead to increased morbidity and mortality. Patients who develop PH due to thromboembolic disease are catalogued as chronic thromboembolic pulmonary hypertension (CTEPH). Anticoagulation remains a topic of interest in these patients. PUBMED, EMBASE and COCHRANE databases were searched by two investigators until December 2023. Information was analyzed for all-cause mortality, venous thromboembolism and major bleeding. We included a total of 10 studies in this meta-analysis. Our pooled analysis demonstrated that DOACs were non-inferior in all-cause mortality [OR 0.88, 95 % CI (0.48, 1.61)], venous thromboembolism [OR 1.00, 95 % CI (0.50, 1.98)] and major bleeding [OR 0.78, 95 % CI (0.43, 1.40)] when compared to VKAs. In conclusion, our meta-analysis supports the use of DOACs in patients with CTEPH. Further randomized trials are still needed to confirm our results in terms of safety and mortality.

Pathophysiology and Treatment of Pulmonary Arterial Hypertension

Pulmonary hypertension (PH) is recognized as a pathophysiological disorder encompassing a wide spectrum of clinical conditions related to various cardiovascular and respiratory diseases [...].

Prevalence and Prognosis of Hypothyroidism in Patients With Chronic Thromboembolic Pulmonary Hypertension: An Updated Review With Description of Case Series

Hypothyroidism has been shown to have several effects on organs, including derangements in the coagulation system, impairing endothelial function, but data on the importance of hypothyroidism in the pathogenesis and development of chronic thromboembolic pulmonary hypertension (CTEPH) are limited. This report presents an updated review of the prevalence and prognosis of hypothyroidism in patients diagnosed with CTEPH, including a detailed retrospective description of the series. The descriptive case series included 34 adult patients diagnosed with CTEPH, of whom 11 patients were diagnosed with hypothyroidism. The prevalence of hypothyroidism in CTEPH was found to be 32.35%. All patients with hypothyroidism had NYHA functional Class II-III. Hemodynamic values obtained through right heart catheterization (RHC) showed that patients with hypothyroidism had significantly higher mean pulmonary arterial pressures (mPAP), with a mean of 56.91 mm Hg vs 43.93 mm Hg (p = 0.026), and the PVR in dynes/sec/cm5 was 932 vs 541 (p = 0.027). Significant differences in PVR were found in wood units (WU) 11.91 vs 7.11 (p = 0.042). The mean level of brain natriuretic peptide (BNP) between both groups was 797.3 pg/mL for patients with hypothyroidism vs 262.02 pg/mL in patients with euthyroidism (p = .032). Hypothyroidism may significantly affect patients' clinical and hemodynamic outcomes in patients with CTEPH. Hypothyroidism as a risk factor in the evaluation and treatment of these patients is vital to optimize outcomes in CTEPH; further research is warranted whether hypothyroidism therapies could alter such outcomes.

Evaluation of total intravenous anesthesia with remimazolam in general anesthesia for pulmonary endarterectomy of chronic thromboembolic pulmonary hypertension: a case report

BACKGROUND

Pulmonary endarterectomy (PEA) is a treatment modality for chronic thromboembolic pulmonary hypertension (CTEPH). PEA requires anesthesia management to prevent an increase in pulmonary vascular resistance (PVR) and circulatory failure. Therefore, it is necessary to select an anesthetic agent that can achieve these goals as much as possible. On the other hand, remimazolam, a short-acting sedative, was launched in Japan in 2020, and its use in various cases has been increasingly reported. This report demonstrates that remimazolam can be used safely in the anesthetic management of PEA.

CASE PRESENTATION

A 57-year-old man was scheduled to undergo PEA for CTEPH. Remimazolam was used for sedation from induction of anesthesia. Hemodynamics were stable during surgery without circulatory failure. Anesthesia was managed intraoperatively without any particular increase in PVR.

DISCUSSION

Anesthesia was successfully managed without any complications. This case suggests that remimazolam is one of the options for anesthetic management in PEA.