Myeloproliferative Diseases as Possible Risk Factor for Development of Chronic Thromboembolic Pulmonary Hypertension-A Genetic Study

Clonal Hematopoiesis in Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

The cause of chronic thromboembolic pulmonary hypertension (CTEPH) remains largely unknown. Recently, clonal hematopoiesis (CH) has been reported to be associated with cardiovascular and thromboembolic diseases. Here, we investigated the prevalence and clinical impact of CH in patients with CTEPH.

METHODS AND RESULTS

Whole-exome sequencing and deep-panel sequencing were performed in 214 patients with CTEPH. Clinical data before and after treatment were compared between patients with and without CH. RNA sequencing and serum analysis were performed to explore the pathogenesis that CH contributes to CTEPH. Among the enrolled patients, 20.1%, notably 44.4% who were 80 to 89 years old, had variants in CH-associated genes. In regard to clinical impact, B-type natriuretic peptide levels and home oxygen therapy rate were significantly higher, and 6-minute walk distance was significantly shorter after treatment in patients with CH than in those without CH. Moreover, novel clot reformation in the pulmonary artery despite the use of anticoagulants and additional angioplasty events after treatment completion were more frequent in patients with CH. RNA sequencing analysis revealed that blood coagulation and neutrophil extracellular trap formation pathways were enriched in patients with CH. Additionally, serum citrullinated histone H3 levels were higher in patients with CH than those without CH. These results were consistent in the subgroup of patients who did not have the history of hematological disorders.

CONCLUSIONS

The findings in this study raise the possibility that CH will induce a more prothrombotic state through neutrophil activation and neutrophil extracellular trap formation, contributing to pathogenesis and poor treatment response in patients with CTEPH.

Myeloproliferative Neoplasms and Cardiovascular Disease: A Review

OPINION STATEMENT

Myeloproliferative neoplasms (MPN) are a heterogenous group of disorders of clonal hematopoiesis characterized by constitutive activation of the JAK/STAT signaling pathway leading to proliferation of blood cells. Cardiovascular disease (CVD) contributes significantly to the morbidity and mortality of patients with MPN. Particularly well-known CVD complications of MPNs are arterial and venous thrombotic events. However, MPNs are also associated with other forms of CVD including atrial fibrillation, heart failure, and pulmonary hypertension. Recent studies have characterized outcomes of patients with MPN and CVD, including acute myocardial infarction (AMI), heart failure, atrial fibrillation, and pulmonary hypertension. Additionally, optimal cardiovascular disease prevention strategies in patients with MPN are not yet clear. Further investigation is warranted to improve CVD outcomes in patients with MPN. Clinicians should be aware of cardiovascular complications of MPN, including thrombotic as well as non-thrombotic complications (heart failure, arrhythmias, pulmonary hypertension).

Genetic background of pulmonary (vascular) diseases - how much is written in the codes?

PURPOSE OF REVIEW

To provide a comprehensive overview of the underlying genetic defects of pulmonary (vascular) diseases and novel treatment avenues.

RECENT FINDINGS

Pulmonary arterial hypertension (PAH) is the prime example of a pulmonary vascular disease, which can be caused by genetic mutations in some patients. Germline mutations in the BMPR2 gene and further genes lead to vessel remodelling, increase of pulmonary vascular resistance and onset of heritable PAH. The PAH genes with the highest evidence and strategies for genetic testing and counselling have been assessed and evaluated in 2023 by international expert consortia. Moreover, first treatment options have just arisen targeting the molecular basis of PAH.

SUMMARY

Apart from PAH, this review touches on the underlying genetic causes of further lung diseases including alpha 1 antitrypsin deficiency, cystic fibrosis, familial pulmonary fibrosis and lymphangioleiomyomatosis. We point out the main disease genes, the underlying pathomechanisms and novel therapies trying not only to relieve symptoms but to treat the molecular causes of the diseases.

Cardiovascular Risk in Philadelphia-Negative Myeloproliferative Neoplasms: Mechanisms and Implications-A Narrative Review

Myeloproliferative neoplasms (MPNs), encompassing disorders like polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are characterized by clonal hematopoiesis without the Philadelphia chromosome. The JAK2 V617F mutation is prevalent in PV, ET, and PMF, while mutations in MPL and CALR also play significant roles. These conditions predispose patients to thrombotic events, with PMF exhibiting the lowest survival among MPNs. Chronic inflammation, driven by cytokine release from aberrant leukocytes and platelets, amplifies cardiovascular risk through various mechanisms, including atherosclerosis and vascular remodeling. Additionally, MPN-related complications like pulmonary hypertension and cardiac fibrosis contribute to cardiovascular morbidity and mortality. This review consolidates recent research on MPNs' cardiovascular implications, emphasizing thrombotic risk, chronic inflammation, and vascular stiffness. Understanding these associations is crucial for developing targeted therapies and improving outcomes in MPN patients.

Clonal Hematopoiesis of Indeterminate Potential in Chronic Thromboembolic Pulmonary Hypertension: A Multicenter Study

BACKGROUND

The pathogenesis of chronic thromboembolic pulmonary hypertension (CTEPH) is multifactorial and growing evidence has indicated that hematological disorders are involved. Clonal hematopoiesis of indeterminate potential (CHIP) has recently been associated with an increased risk of both hematological malignancies and cardiovascular diseases. However, the prevalence and clinical relevance of CHIP in patients with CTEPH remains unclear.

METHODS

Using stepwise calling on next-generation sequencing data from 499 patients with CTEPH referred to 3 centers between October 2006 and December 2021, CHIP mutations were identified. We associated CHIP with all-cause mortality in patients with CTEPH. To provide insights into potential mechanisms, the associations between CHIP and inflammatory markers were also determined.

RESULTS

In total, 47 (9.4%) patients with CTEPH carried at least 1 CHIP mutation at a variant allele frequency of ≥2%. The most common mutations were in DNMT3A, TET2, RUNX1, and ASXL1. During follow-up (mean, 55 months), deaths occurred in 22 (46.8%) and 104 (23.0%) patients in the CHIP and non-CHIP groups, respectively (P<0.001, log-rank test). The association of CHIP with mortality remained robust in the fully adjusted model (hazard ratio, 2.190 [95% CI, 1.257-3.816]; P=0.006). Moreover, patients with CHIP mutations showed higher circulating interleukin-1β and interleukin-6 and lower interleukin-4 and IgG galactosylation levels.

CONCLUSIONS

This is the first study to show that CHIP mutations occurred in 9.4% of patients with CTEPH are associated with a severe inflammatory state and confer a poorer prognosis in long-term follow-up.

[Genetic counselling and testing in pulmonary arterial hypertension - A consensus statement on behalf of the International Consortium for Genetic Studies in PAH - French version]

Pulmonary arterial hypertension (PAH) is a rare disease that can be caused by (likely) pathogenic germline genomic variants. In addition to the most prevalent disease gene, BMPR2 (bone morphogenetic protein receptor 2), several genes, some belonging to distinct functional classes, are also now known to predispose to the development of PAH. As a consequence, specialist and non-specialist clinicians and healthcare professionals are increasingly faced with a range of questions regarding the need for, approaches to and benefits/risks of genetic testing for PAH patients and/or related family members. We provide a consensus-based approach to recommendations for genetic counselling and assessment of current best practice for disease gene testing. We provide a framework and the type of information to be provided to patients and relatives through the process of genetic counselling, and describe the presently known disease causal genes to be analysed. Benefits of including molecular genetic testing within the management protocol of patients with PAH include the identification of individuals misclassified by other diagnostic approaches, the optimisation of phenotypic characterisation for aggregation of outcome data, including in clinical trials, and importantly through cascade screening, the detection of healthy causal variant carriers, to whom regular assessment should be offered.

Defining the clinical validity of genes reported to cause pulmonary arterial hypertension

PURPOSE

Pulmonary arterial hypertension (PAH) is a rare, progressive vasculopathy with significant cardiopulmonary morbidity and mortality. Genetic testing is currently recommended for adults diagnosed with heritable, idiopathic, anorexigen-, hereditary hemorrhagic telangiectasia-, and congenital heart disease-associated PAH, PAH with overt features of venous/capillary involvement, and all children diagnosed with PAH. Variants in at least 27 genes have putative evidence for PAH causality. Rigorous assessment of the evidence is needed to inform genetic testing.

METHODS

An international panel of experts in PAH applied a semi-quantitative scoring system developed by the NIH Clinical Genome Resource to classify the relative strength of evidence supporting PAH gene-disease relationships based on genetic and experimental evidence.

RESULTS

Twelve genes (BMPR2, ACVRL1, ATP13A3, CAV1, EIF2AK4, ENG, GDF2, KCNK3, KDR, SMAD9, SOX17, and TBX4) were classified as having definitive evidence and 3 genes (ABCC8, GGCX, and TET2) with moderate evidence. Six genes (AQP1, BMP10, FBLN2, KLF2, KLK1, and PDGFD) were classified as having limited evidence for causal effects of variants. TOPBP1 was classified as having no known PAH relationship. Five genes (BMPR1A, BMPR1B, NOTCH3, SMAD1, and SMAD4) were disputed because of a paucity of genetic evidence over time.

CONCLUSION

We recommend that genetic testing includes all genes with definitive evidence and that caution be taken in the interpretation of variants identified in genes with moderate or limited evidence. Genes with no known evidence for PAH or disputed genes should not be included in genetic testing.

Antiproliferative effect of selexipag active metabolite MRE-269 on pulmonary arterial smooth muscle cells from patients with chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a group 4 pulmonary hypertension (PH) characterized by nonresolving thromboembolism in the central pulmonary artery and vascular occlusion in the proximal and distal pulmonary artery. Medical therapy is chosen for patients who are ineligible for pulmonary endarterectomy or balloon pulmonary angioplasty or who have symptomatic residual PH after surgery or intervention. Selexipag, an oral prostacyclin receptor agonist and potent vasodilator, was approved for CTEPH in Japan in 2021. To evaluate the pharmacological effect of selexipag on vascular occlusion in CTEPH, we examined how its active metabolite MRE-269 affects platelet-derived growth factor-stimulated pulmonary arterial smooth muscle cells (PASMCs) from CTEPH patients. MRE-269 showed a more potent antiproliferative effect on PASMCs from CTEPH patients than on those from normal subjects. DNA-binding protein inhibitor (ID) genes ID1 and ID3 were found by RNA sequencing and real-time quantitative polymerase chain reaction to be expressed at lower levels in PASMCs from CTEPH patients than in those from normal subjects and were upregulated by MRE-269 treatment. ID1 and ID3 upregulation by MRE-269 was blocked by co-incubation with a prostacyclin receptor antagonist, and ID1 knockdown by small interfering RNA transfection attenuated the antiproliferative effect of MRE-269. ID signaling may be involved in the antiproliferative effect of MRE-269 on PASMCs. This is the first study to demonstrate the pharmacological effects on PASMCs from CTEPH patients of a drug approved for the treatment of CTEPH. Both the vasodilatory and the antiproliferative effect of MRE-269 may contribute to the efficacy of selexipag in CTEPH.

Genetic counselling and testing in pulmonary arterial hypertension: a consensus statement on behalf of the International Consortium for Genetic Studies in PAH

Pulmonary arterial hypertension (PAH) is a rare disease that can be caused by (likely) pathogenic germline genomic variants. In addition to the most prevalent disease gene, BMPR2 (bone morphogenetic protein receptor 2), several genes, some belonging to distinct functional classes, are also now known to predispose to the development of PAH. As a consequence, specialist and non-specialist clinicians and healthcare professionals are increasingly faced with a range of questions regarding the need for, approaches to and benefits/risks of genetic testing for PAH patients and/or related family members. We provide a consensus-based approach to recommendations for genetic counselling and assessment of current best practice for disease gene testing. We provide a framework and the type of information to be provided to patients and relatives through the process of genetic counselling, and describe the presently known disease causal genes to be analysed. Benefits of including molecular genetic testing within the management protocol of patients with PAH include the identification of individuals misclassified by other diagnostic approaches, the optimisation of phenotypic characterisation for aggregation of outcome data, including in clinical trials, and importantly through cascade screening, the detection of healthy causal variant carriers, to whom regular assessment should be offered.

Cardiovascular Disease in Myeloproliferative Neoplasms: JACC: CardioOncology State-of-the-Art Review

Myeloproliferative neoplasms are associated with increased risk for thrombotic complications. These conditions most commonly involve somatic mutations in genes that lead to constitutive activation of the Janus-associated kinase signaling pathway (eg, Janus kinase 2, calreticulin, myeloproliferative leukemia protein). Acquired gain-of-function mutations in these genes, particularly Janus kinase 2, can cause a spectrum of disorders, ranging from clonal hematopoiesis of indeterminate potential, a recently recognized age-related promoter of cardiovascular disease, to frank hematologic malignancy. Beyond thrombosis, patients with myeloproliferative neoplasms can develop other cardiovascular conditions, including heart failure and pulmonary hypertension. The authors review the pathophysiologic mechanisms of cardiovascular complications of myeloproliferative neoplasms, which involve inflammation, prothrombotic and profibrotic factors (including transforming growth factor-beta and lysyl oxidase), and abnormal function of circulating clones of mutated leukocytes and platelets from affected individuals. Anti-inflammatory therapies may provide cardiovascular benefit in patients with myeloproliferative neoplasms, a hypothesis that requires rigorous evaluation in clinical trials.

Reduction of BMPR2 mRNA Expression in Peripheral Blood of Pulmonary Arterial Hypertension Patients: A Marker for Disease Severity?

Pulmonary arterial hypertension (PAH) can be caused by pathogenic variants in the gene bone morphogenetic protein receptor 2 (BMPR2). While BMPR2 protein expression levels are known to be reduced in the lung tissue of heritable PAH (HPAH) patients, a systematic study evaluating expression in more easily accessible blood samples and its clinical relevance is lacking. Thus, we analyzed the BMPR2 mRNA expression in idiopathic/HPAH patients and healthy controls in blood by quantitative polymerase chain reaction and protein expression by enzyme-linked immunosorbent assay. Clinical parameters included right heart catherization, echocardiography, six-minute walking test and laboratory tests. BMPR2 variant-carriers (n = 23) showed significantly lower BMPR2 mRNA expression in comparison to non-carriers (n = 56) and healthy controls (n = 30; p < 0.0001). No difference in BMPR2 protein expression was detected. Lower BMPR2 mRNA expression correlated significantly with greater systolic pulmonary artery pressure and pulmonary vascular resistance. Higher BMPR2 mRNA expression correlated with greater glomerular filtration rate, cardiac index and six-minute walking distance. We demonstrated the feasibility to assess BMPR2 expression in blood and, for the first time, that BMPR2 mRNA expression levels are significantly reduced in variant carriers and correlated with clinical parameters. Further studies may evaluate the usefulness of BMPR2 mRNA expression in blood as a new marker for disease severity.

Integrated Bioinformatics Analysis Reveals Marker Genes and Potential Therapeutic Targets for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare cardiovascular disease with very high mortality rate. The currently available therapeutic strategies, which improve symptoms, cannot fundamentally reverse the condition. Thus, new therapeutic strategies need to be established. Our research analyzed three microarray datasets of lung tissues from human PAH samples retrieved from the Gene Expression Omnibus (GEO) database. We combined two datasets for subsequent analyses, with the batch effects removed. In the merged dataset, 542 DEGs were identified and the key module relevant to PAH was selected using WGCNA. GO and KEGG analyses of DEGs and the key module indicated that the pre-ribosome, ribosome biogenesis, centriole, ATPase activity, helicase activity, hypertrophic cardiomyopathy, melanoma, and dilated cardiomyopathy pathways are involved in PAH. With the filtering standard (|MM| > 0.95 and |GS| > 0.90), 70 hub genes were identified. Subsequently, five candidate marker genes (CDC5L, AP3B1, ZFYVE16, DDX46, and PHAX) in the key module were found through overlapping with the top thirty genes calculated by two different methods in CytoHubb. Two of them (CDC5L and DDX46) were found to be significantly upregulated both in the merged dataset and the validating dataset in PAH patients. Meanwhile, expression of the selected genes in lung from PAH chicken measured by qRT-PCR and the ROC curve analyses further verified the potential marker genes' predictive value for PAH. In conclusion, CDC5L and DDX46 may be marker genes and potential therapeutic targets for PAH.