Pulmonary veno-occlusive disease: illustrative cases and literature review.

Pulmonary veno-occlusive disease (PVOD), also known as "pulmonary arterial hypertension (PAH) with overt features of venous/capillary involvement", is a rare cause of PAH characterised by substantial small pulmonary vein and capillary involvement, leading to increased pulmonary vascular resistance and right ventricular failure. Environmental risk factors have been associated with the development of PVOD, such as occupational exposure to organic solvents and chemotherapy, notably mitomycin. PVOD may also be associated with a mutation in the EIF2AK4 gene in heritable forms of disease. Distinguishing PVOD from PAH is critical for guiding appropriate management. Chest computed tomography typically displays interlobular septal thickening, ground-glass opacities and mediastinal lymphadenopathy. Life-threatening pulmonary oedema is a complication of pulmonary vasodilator therapy that can occur with any class of PAH drugs in PVOD. Early referral to a lung transplant centre is essential due to the poor response to therapy when compared with other forms of PAH. Histopathological analysis of lung explants reveals microvascular remodelling with typical fibrous veno-occlusive lesions. This review covers the main features distinguishing PVOD from PAH and two clinical cases that illustrate the challenges of PVOD management.

[Genetic diagnostics and molecular approaches in pulmonary arterial hypertension]. / Genetische Diagnostik und molekulare Ansätze bei pulmonalarterieller Hypertonie.

The recently published new European guidelines for diagnosis and treatment of pulmonary hypertension now offer the so far most extensive description of genetic testing and counselling for pulmonary arterial hypertension patients. In addition, the importance of a clinical screening of healthy mutation carriers is highlighted as well as the genetic testing of patients with a suspicion of pulmonary veno-occlusive disease. We frame the respective parts of the guidelines on genetic testing and counselling in the context of recent data and provide comments. Finally, we give an outlook on novel molecular approaches starting from Sotatercept, addressing ion channels and novel therapeutic developments.

Diagnosis and management of pulmonary veno-occlusive disease.

INTRODUCTION: Pulmonary veno-occlusive disease (PVOD) is an orphan disease and uncommon etiology of pulmonary arterial hypertension (PAH) characterized by substantial small pulmonary vein and capillary involvement. AREAS COVERED: PVOD, also known as 'PAH with features of venous/capillary involvement' in the current ESC/ERS classification. EXPERT OPINION: In recent years, particular risk factors for PVOD have been recognized, including genetic susceptibilities and environmental factors (such as exposure to occupational organic solvents, chemotherapy, and potentially tobacco). The discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD has been a breakthrough in understanding the molecular basis of PVOD. Venous and capillary involvement (PVOD-like) has also been reported to be relatively common in connective tissue disease-associated PAH (especially systemic sclerosis), and in rare pulmonary diseases like sarcoidosis and pulmonary Langerhans cell granulomatosis. Although PVOD and pulmonary arterial hypertension (PAH) exhibit similarities, including severe precapillary PH, it is essential to differentiate between them since PVOD has a worse prognosis and requires specific management. Indeed, PVOD patients are characterized by poor response to PAH-approved drugs, which can lead to pulmonary edema and clinical deterioration. Due to the lack of effective treatments, early referral to a lung transplantation center is crucial.

T-cell dysregulation and inflammatory process in Gcn2 (Eif2ak4-/-)-deficient rats in basal and stress conditions.

Hereditary pulmonary veno-occlusive disease (hPVOD) is a severe form of autosomal recessive pulmonary hypertension and is due to biallelic loss of function of the EIF2AK4 gene (alias GCN2) coding for GCN2. GCN2 is a stress kinase that belongs to the integrated stress response pathway (ISR). Three rat lines carrying biallelic Gcn2 mutation were generated and found phenotypically normal and did not spontaneously develop a PVOD-related disease. We submitted these rats to amino acid deprivation to document the molecular and cellular response of the lungs and to identify phenotypic changes that could be involved in PVOD pathophysiology. Gcn2-/- rat lungs were analyzed under basal conditions and 3 days after a single administration of PEG-asparaginase (ASNase). Lung mRNAs were analyzed by RNAseq and single-cell RNAseq (scRNA-seq), flow cytometry, tissue imaging, and Western blots. The ISR was not activated after ASNase treatment in Gcn2-/- rat lungs, and apoptosis was increased. Several proinflammatory and innate immunity genes were overexpressed, and inflammatory cells infiltration was also observed in the perivascular area. Under basal conditions, scRNA-seq analysis of Gcn2-/- rat lungs revealed increases in two T-cell populations, a LAG3+ T-cell population and a proliferative T-cell population. Following ASNase administration, we observed an increase in calprotectin expression involved in TLR pathway activation and neutrophil infiltration. In conclusion, under basal and asparagine and glutamine deprivation induced by asparaginase administration, Gcn2-/- rats display molecular and cellular signatures in the lungs that may indicate a role for Gcn2 in immune homeostasis and provide further clues to the mechanisms of hPVOD development.

Pulmonary veno-occlusive disease in Sjogren's syndrome: a case report.

BACKGROUND: Pulmonary arterial hypertension (PAH) associated with connective tissue disease (CTD) belongs to Group 1 pulmonary hypertension. Pulmonary veno-occlusive disease (PVOD), which is characterized by venous system aberrations, has been previously reported in CTD-PAH; however, it has rarely been observed in Sjogren's syndrome (SS). CASE PRESENTATION: Our 28-year-old female patient was admitted to the hospital with recurrent shortness of breath even after minimal physical activity. Her chest high-resolution CT scan demonstrated pulmonary artery dilatation and bilateral ground-glass nodules. A subsequent right heart catheterization confirmed pulmonary hypertension because her mean pulmonary arterial pressure was 62 mmHg. Our inquisitive genomic assessment identified a novel EIF2AK4 mutation at c.1021 C > T (p. Gln341*), the dominant causal gene of PVOD. Histological examination demonstrated stenosis and occlusions in the pulmonary veins. Because she presented with features such as dry eyes and Raynaud's phenomenon, we performed a biopsy on the labial salivary gland, which confirmed SS. Her treatment regimen included PAH-targeted therapies (tadalafil and macitentan) in combination with hydroxychloroquine. Although she was hospitalized several times due to acute exacerbation of PAH, her disease progression was under control, and she did not demonstrate any signs of pulmonary edema even after a three-year treatment period. CONCLUSION: Here, we report the case of an SS-PAH patient with PVOD who carried a novel biallelic EIF2AK4 mutation, and PAH-targeted therapies were well tolerated by our patient.

Lipidomic Profile Analysis of Lung Tissues Revealed Lipointoxication in Pulmonary Veno-Occlusive Disease.

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary arterial hypertension (PAH) occurring in a heritable form (hPVOD) due to biallelic inactivating mutations of EIF2AK4 (encoding GCN2, general control nonderepressible 2) or in a sporadic form in older age (sPVOD), following exposure to chemotherapy or organic solvents. In contrast to PAH, PVOD is characterized by a particular remodeling of the pulmonary venous system and the obliteration of small pulmonary veins by fibrous intimal thickening and patchy capillary proliferation. The pathobiological knowledge of PVOD is poor, explaining the absence of medical therapy for PVOD. Lung transplantation remains the only therapy for eligible PVOD patients. As we recently demonstrated, respiratory diseases, chronic obstructive pulmonary disease, or cystic fibrosis exhibit lipointoxication signatures characterized by excessive levels of saturated phospholipids contributing to the pathological features of these diseases, including endoplasmic reticulum stress, pro-inflammatory cytokines production, and bronchoconstriction. In this study, we investigated and compared the clinical data and lung lipid signature of control (10 patients), idiopathic PAH (7 patients), heritable PAH (9 BMPR2 mutations carriers), hPVOD (10 EIF2AK4 mutation carriers), and sPVOD (6 non-carriers) subjects. Mass spectrometry analyses demonstrated lung lipointoxication only in hPVOD patients, characterized by an increased abundance of saturated phosphatidylcholine (PC) at the expense of the polyunsaturated species in the lungs of hPVOD patients. The present data suggest that lipointoxication could be a potential player in the etiology of PVOD.

A rare compound heterozygous EIF2AK4 mutation in pulmonary veno-occlusive disease.

BACKGROUND: Pulmonary veno-occlusive disease (PVOD) is a rare, progressive, and oft-fatal condition of pulmonary arterial hypertension that is typically difficult to diagnose and treat. However, with the development of next-generation sequencing technology, an increasing number of patients with PVOD are being diagnosed. METHODS: Initially, we used whole exome sequencing (WES) to identify the proband as a rare compound heterozygous mutation of EIF2AK4 in PVOD. Subsequently, the parents of patient underwent EIF2AK4 screening by Sanger sequencing. RESULTS: In this study, we describe the family tree of a patient with PVOD with a rare compound heterozygous EIF2AK4 mutation. Moreover, we identified a new EIF2AK4 mutation, c.2236_2237insAAGTCCTTCT, in exon 12 of the proband and his mother. This frameshift mutation led to premature termination of the coding protein sequence and widespread loss of protein function, which promoted the development of PVOD. CONCLUSIONS: Our results expand our understanding of the EIF2AK4 mutation spectrum in patients with PVOD, as well as highlight the clinical applicability of WES.

Patient-specific and gene-corrected induced pluripotent stem cell-derived endothelial cells elucidate single-cell phenotype of pulmonary veno-occlusive disease.

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension characterized by the preferential remodeling of the pulmonary venules. Hereditary PVOD is caused by biallelic variants of the EIF2AK4 gene. Three PVOD patients who carried the compound heterozygous variants of EIF2AK4 and two healthy controls were recruited and induced pluripotent stem cells (iPSCs) were generated from human peripheral blood mononuclear cells (PBMCs). The EIF2AK4 c.2965C>T variant (PVOD#1), c.3460A>T variant (PVOD#2), and c.4832_4833insAAAG variant (PVOD#3) were corrected by CRISPR-Cas9 in PVOD-iPSCs to generate isogenic controls and gene-corrected-iPSCs (GC-iPSCs). PVOD-iPSC-endothelial cells (ECs) exhibited a decrease in GCN2 protein and mRNA expression when compared with control and GC-ECs. PVOD-ECs exhibited an abnormal EC phenotype featured by excessive proliferation and angiogenesis. The abnormal phenotype of PVOD-ECs was normalized by protein kinase B inhibitors AZD5363 and MK2206. These findings help elucidate the underlying molecular mechanism of PVOD in humans and to identify promising therapeutic drugs for treating the disease.

Pediatric pulmonary veno-occlusive disease associated with a novel BMPR2 variant.

Pulmonary veno-occlusive disease (PVOD) and idiopathic/heritable pulmonary arterial hypertension (I/HPAH) cause progressive PH on the distinct genetic impact. A 29-month-old boy presented with a loss of consciousness. He had severe PH refractory to pulmonary vasodilators. Hypoxemia and ground-glass opacity on the chest computed tomography were present, and significant pulmonary edema developed after the introduction of continuous intravenous prostaglandin I2 . Based on the clinical diagnosis of PVOD, he underwent a single living-donor lobar lung transplantation with the right lower lobe of his mother. The pathological findings of his explanted lung showed intimal thickening and luminal narrowing of the pulmonary vein. A genetic test revealed a novel heterozygous splice acceptor variant (c.77-2A>C) in BMPR2, which is typically associated with I/HPAH. This is the first pediatric case of PVOD with BMPR2 variant, supporting the concept that I/HPAH and PVOD are part of a spectrum of pulmonary vascular disease.

Identification of a Novel EIF2AK Variant and Genetics-Assisted Approach to Diagnosis of Pulmonary Capillary Hemangiomatosis.

Pulmonary capillary hemangiomatosis (PCH) is an uncommon type of pulmonary vascular disease characterized by capillary proliferation and very poor prognosis owing to misdiagnosis and lack of effective therapeutic options. Mutations in the eukaryotic translation initiation factor 2α kinase 4 (EIF2AK4) gene have been reported in pulmonary veno-occlusive disease and PCH. In this report, we present a patient whose diagnosis of PCH was delayed by 2 ½ years despite prior surgical lung biopsy and clinical and laboratory findings suggestive of pulmonary hypertension. Genotyping revealed a novel likely pathogenic variant in the EIF2AK4 gene. Review of surgical lung biopsy performed 2 ½ years prior confirmed PCH histology along with constrictive bronchiolitis.

A 24-Year-Old Woman With Dyspnea, Chest Pain, and Dry Cough.

CASE PRESENTATION: A 24-year-old woman, a baby-sitter with no known comorbidities, presented to the outpatient department with complaints of modified Medical Research Council grade IV breathlessness for 3 months, chest pain, and dry cough for 2 weeks. There was no known disease history, including respiratory, flu-like illness, or connective tissue disorder. There was no use of chemotherapeutic, oral contraceptive drugs, exposure to toxic substances, or smoking. A review of systems was negative for fever, arthralgia, myalgia, Raynaud phenomenon, skin thickening, rash, or leg swelling. The patient had no family history suggestive of a genetic syndrome.

Good response to pulmonary arterial hypertension-targeted therapy in 2 pulmonary veno-occlusive disease patients: A case report.

RATIONALE: Pulmonary veno-occlusive disease (PVOD) is a kind of rare and fatal pulmonary arterial hypertension (PAH). Different from other subtypes of PAH, PVOD patients have a very poor prognosis because of the progressive nature of pulmonary vascular involvement and fatal pulmonary edema induced by PAH-targeted drugs. Lung transplantation is the only choice for these patients. PATIENT CONCERNS: We reported 2 cases of PVOD which was misdiagnosed as idiopathic pulmonary arterial hypertension initially due to the lack of typical findings of PVOD. Right heart catheterization was done. The results showed severe PAH with mean pulmonary artery pressure at 76 mmHg and 68 mmHg. DIAGNOSIS: The diagnosis of idiopathic pulmonary arterial hypertension was corrected by eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) mutation screening. Biallelic mutations (c.1387delT (p. Arg463fs); c.989-990 delAA (p. Lys330fs)) were detected by next-generation sequencing for whole exome from blood sample. The presence of biallelic EIF2AK4 mutation was sufficient to confirm the diagnosis of PVOD. INTERVENTIONS: The 2 patients had good response to PAH-targeted therapy (Ambrisentan 10 mg once a day and tadalafil 20 mg once a day) in the following 1 year. OUTCOMES: Because the patients had a good response to targeted drugs, the treatment of the 2 cases was unchanged. Over 1-year period, they still have a good response to PAH-targeted drugs. There was no sign of pulmonary edema. LESSONS: All these results may indicate that PVOD is not so rare and typical findings of PVOD are lacking in some patients. EIF2AK4 mutation screening by next-generation sequencing maybe useful to differentiate PVOD from other PAH subtypes. PVOD is a heterogeneity population and different patients have different characteristics including response to PAH-targeted therapy. How to pick off this portion of patients timely is the core issue. Further study is necessary to answer this question.

GCN2 Regulates ATF3-p38 MAPK Signaling Transduction in Pulmonary Veno-Occlusive Disease.

Pulmonary veno-occlusive disease (PVOD) is a fatal disease of pulmonary vascular lesions leading to right heart failure. Heritable PVOD (hPVOD) is related to biallelic mutation of EIF2AK4 (encoding GCN2), but its molecular mechanism remains unclear. In this study, we aimed to investigate the pathogenesis of PVOD and to find potential drug targets for PVOD. GCN2 dysfunction led to an enhanced transcription of collagen I gene (col1a1 and col1a2) through decreasing ATF3-dependent p38 phosphorylation inhibition in PVOD, which promotes the collagen I synthesis in pulmonary arterial smooth muscle cells (PASMCs) and eventually leads to increased collagen deposition in pulmonary artery. Four GCN2 knockout (KO) cell lines (exon 15 or 33 mutation) were successfully constructed by epiCRISPR system. Two induced pluripotent stem cells (iPSCs) were generated by reprogramming peripheral blood mononuclear cells (PBMCs) of PVOD patient. It was also comfirmed that GCN2 dysfunction could lead to increased expression of collagen I in lateral plate mesoderm lineage-smooth muscle cells (LM-SMCs) differentiated from both GCN2 KO cell lines and iPSCs. SB203580 (a specific inhibitor of p38) improved hemodynamics and pulmonary vascular remodeling in mitomycin C (MMC)-induced PVOD rats by right ventricle echocardiography. On the whole, we proposed that GCN2 deficiency decreased ATF3-dependent p38 phosphorylation inhibition in PVOD development and suggested a potential therapeutic reagent of SB203580 for the treatment of the disease.

[Familial pulmonary veno-occlusive disease with a composite biallelic heterozygous EIF2AK4 mutation]. / Une maladie veino-occlusive pulmonaire familiale avec mutation biallélique hétérozygote composite d'EIF2AK4.

Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension. Heritable and sporadic forms have been distinguished. Hypoxemia, profound reduction in the diffusion of carbon monoxide and haemodynamic confirmation of pre-capillary pulmonary hypertension are the major diagnostic criteria. Thoracic CT scanning and a response to pharmaceutical therapy provide additional information to confirm the diagnosis. A 52-year-old patient, three of whose siblings had pulmonary hypertension, was admitted with dyspnoea, malaise and palpitations. Right heart catheterisation confirmed pre-capillary pulmonary hypertension. A search for an EIF2AK4 mutation was carried out, and this showed a composite biallelic heterozygous mutation compatible with the diagnosis of familial PVOD, identical to that showed in one of his brothers. Given the signs of severity of the disease and the diagnosis of PVOD, whose response to pharmaceutical therapy is often poor, the patient was placed on a waiting list for lung transplantation. Despite a similar diagnosis in 3 brothers and follow-up proposed 11 years before the diagnosis, pulmonary hypertension appeared within a few weeks and led immediately to a severe clinical situation. Annual clinical and echocardiographic monitoring had been strongly advised to the patient, but had not allowed diagnosis at a mild or moderate stage of the disease. This clinical case shows that the identification of factors predicting the development of heritable PVOD at a pre-symptomatic stage is an important issue for clinical research.

Genetic Evaluation in a Cohort of 126 Dutch Pulmonary Arterial Hypertension Patients.

Pulmonary arterial hypertension (PAH) is a severe, life-threatening disease, and in some cases is caused by genetic defects. This study sought to assess the diagnostic yield of genetic testing in a Dutch cohort of 126 PAH patients. Historically, genetic testing in the Netherlands consisted of the analysis of BMPR2 and SMAD9. These genes were analyzed in 70 of the 126 patients. A (likely) pathogenic (LP/P) variant was detected in 22 (31%) of them. After the identification of additional PAH associated genes, a next generation sequencing (NGS) panel consisting of 19 genes was developed in 2018. Additional genetic testing was offered to the 48 BMPR2 and SMAD9 negative patients, out of which 28 opted for NGS analysis. In addition, this gene panel was analyzed in 56 newly identified idiopathic (IPAH) or pulmonary veno occlusive disease (PVOD) patients. In these 84 patients, NGS panel testing revealed LP/P variants in BMPR2 (N = 4), GDF2 (N = 2), EIF2AK4 (N = 1), and TBX4 (N = 3). Furthermore, 134 relatives of 32 probands with a LP/P variant were tested, yielding 41 carriers. NGS panel screening offered to IPAH/PVOD patients led to the identification of LP/P variants in GDF2, EIF2AK4, and TBX4 in six additional patients. The identification of LP/P variants in patients allows for screening of at-risk relatives, enabling the early identification of PAH.

Customized Massive Parallel Sequencing Panel for Diagnosis of Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension is a very infrequent disease, with a variable etiology and clinical expressivity, making sometimes the clinical diagnosis a challenge. Current classification based on clinical features does not reflect the underlying molecular profiling of these groups. The advance in massive parallel sequencing in PAH has allowed for the describing of several new causative and susceptibility genes related to PAH, improving overall patient diagnosis. In order to address the molecular diagnosis of patients with PAH we designed, validated, and routinely applied a custom panel including 21 genes. Three hundred patients from the National Spanish PAH Registry (REHAP) were included in the analysis. A custom script was developed to annotate and filter the variants. Variant classification was performed according to the ACMG guidelines. Pathogenic and likely pathogenic variants have been found in 15% of the patients with 12% of variants of unknown significance (VUS). We have found variants in patients with connective tissue disease (CTD) and congenital heart disease (CHD). In addition, in a small proportion of patients (1.75%), we observed a possible digenic mode of inheritance. These results stand out the importance of the genetic testing of patients with associated forms of PAH (i.e., CHD and CTD) additionally to the classical IPAH and HPAH forms. Molecular confirmation of the clinical presumptive diagnosis is required in cases with a high clinical overlapping to carry out proper management and follow up of the individuals with the disease.

Pulmonary capillary hemangiomatosis in Chinese patients without EIF2AK4 mutations.

BACKGROUND: Pulmonary capillary hemangiomatosis (PCH) is a very rare and refractory pulmonary vascular disease that causes pulmonary hypertension. Differentiation of PCH from idiopathic pulmonary arterial hypertension (iPAH) is essential because treatment and prognosis can vary greatly between these two diseases. CASE PRESENTATION: A 20-year-old female and a 33-year-old male both presented with progressive exertional dyspnea and cough. High-resolution computed tomography (HRCT) showed bilateral, diffuse, ill-defined centrilobular nodules of ground-glass opacity, without subpleural thickened septal lines or mediastinal lymphadenopathy. Both cases showed clinical and imaging features characteristic of pulmonary veno-occlusive disease (PVOD) or PCH. The entire EIF2AK4 coding sequence was detected with Sanger sequencing, and no pathogenic EIF2AK4 mutations were identified in either case. Video-assisted thoracoscopic surgery (VATS) was safely performed in both cases, and histopathological examinations of biopsies showed that both patients had PCH. CONCLUSION: Two patients presented with clinical and imaging characteristics suspicious for PVOD/PCH. Despite having no pathogenic EIF2AK4 mutations, both were diagnosed with PCH by VATS lung biopsies. The diagnostic distinction of PCH is important to prompt timely evaluations of patients who may need lung transplantations.