Pulmonary veno-occlusive disease as an occupational lung disease

Comparison of Human and Experimental Pulmonary Veno-Occlusive Disease

Pulmonary veno-occlusive disease (PVOD) occurs in humans either as a heritable form (hPVOD) due to biallelic inactivating mutations of EIF2AK4 (encoding GCN2) or as a sporadic form in older age (sPVOD). The chemotherapeutic agent mitomycin C (MMC) is a potent inducer of PVOD in humans and in rats (MMC-PVOD). Here, we compared human hPVOD and sPVOD, and MMC-PVOD pathophysiology at the histological, cellular, and molecular levels to unravel common altered pathomechanisms. MMC exposure in rats was associated primarily with arterial and microvessel remodeling, and secondarily by venous remodeling, when PVOD became symptomatic. In all forms of PVOD tested, there was convergent GCN2-dependent but eIF2α-independent pulmonary protein overexpression of HO-1 (heme oxygenase 1) and CHOP (CCAAT-enhancer-binding protein [C/EBP] homologous protein), two downstream effectors of GCN2 signaling and endoplasmic reticulum stress. In human PVOD samples, CHOP immunohistochemical staining mainly labeled endothelial cells in remodeled veins and arteries. Strong HO-1 staining was observed only within capillary hemangiomatosis foci, where intense microvascular proliferation occurs. HO-1 and CHOP stainings were not observed in control and pulmonary arterial hypertension lung tissues, supporting the specificity for CHOP and HO-1 involvement in PVOD pathobiology. In vivo loss of GCN2 (EIF2AK4 mutations carriers and Eif2ak4^-/- rats) or in vitro GCN2 inhibition in cultured pulmonary artery endothelial cells using pharmacological and siRNA approaches demonstrated that GCN2 loss of function negatively regulates BMP (bone morphogenetic protein)-dependent SMAD1/5/9 signaling. Exogenous BMP9 was still able to reverse GCN2 inhibition-induced proliferation of pulmonary artery endothelial cells. In conclusion, we identified CHOP and HO-1 inhibition, and BMP9, as potential therapeutic options for PVOD.

Case 276: Pulmonary Veno-Occlusive Disease and Pulmonary Capillary Hemangiomatosis Disease

HistoryA 34-year-old man presented to the emergency department of our hospital for progressive shortness of breath and worsening productive cough of 2 weeks duration. He reported a 10-kg weight loss over 4 months but denied experiencing fever, chills, night sweats, or gastrointestinal, musculoskeletal, or neurologic symptoms. His medical history was unremarkable. Although he was a native of Morocco, he had lived in Europe for many years and worked as a truck driver. The patient had a smoking history but had quit smoking 5 years prior to presentation. He denied alcohol abuse or recreational drug use. He did not have any allergies. Besides bilateral clubbing, the physical examination findings were normal. At the time of admission, he had an oxygen (O₂) saturation of 87% at ambient air, which increased to 100% with 1 L of O₂ administered via a nasal cannula. The blood sample revealed a slight increase in his hemoglobin concentration (18.7 g/dL; normal range, 13.6-17.2 g/dL) and hematocrit level (50.8%; normal range, 39%-49%). His inflammatory parameters were normal, as were his hepatic and renal function. The arterial blood gas test showed partially compensated pulmonary alkalosis (pH, 7.43; normal range, 7.35-7.42; PCO₂, 26 mmHg; normal range, 38-42 mmHg; PO₂, 89 mmHg; normal range, 75-100 mmHg; bicarbonate level, 17 mEq/L [17 mmol/L]; normal range 22-26 mEq/L [22-26 mmol/L]). The results of the pulmonary function tests were expressed as the percentage of predicted values and were 92% for forced vital capacity, 93% for forced expiratory volume in 1 second, 116% for total lung capacity, and 60% for diffusing capacity of carbon monoxide. Anteroposterior chest radiography and enhanced chest CT were also performed at admission.

Learning from registries in pulmonary arterial hypertension: pitfalls and recommendations

Pulmonary arterial hypertension is a rare and incurable chronic disease characterised by a progressive increase in pulmonary vascular resistance and right heart failure. Patient registries collecting observational data can be of great value in the understanding of clinical problems. While clinical trials provide data in selected patient populations, registries better depict real-life practice. This review aims to reflect the input of patient registries in the general knowledge of the disease. Advances in epidemiology of the different subgroups, including data on incidence and/or prevalence, increasing age at presentation and stagnating diagnostic delay are reported. The importance of haemodynamic definition criteria and cardiac comorbidities are underscored. The review also shows the major transformation that pulmonary arterial hypertension therapeutic management has undergone, with still insufficient use of combination therapies; consecutive improvement in outcome; upcoming evidence in disfavour of anticoagulation; and validity of the available risk-stratification tools derived from large registries. Product registries are also briefly presented. Finally, the benefits of registries and methodological aspects are discussed, including immortal time bias, registry data quality and recommendations from EU organisations (EUCERD and PARENT).

Pulmonary veno-occlusive disease in a patient with recently diagnosed systemic sclerosis

Pulmonary veno-occlusive disease is a rare cause of pulmonary hypertension in patients with systemic sclerosis that can be misclassified as pulmonary arterial hypertension. Differentiation between pulmonary veno-occlusive disease and pulmonary arterial hypertension is challenging because of the similar clinical picture. Nevertheless, discrimination is important because pulmonary veno-occlusive disease has a worse prognosis. Vasodilators including phosphodiesterase type 5 inhibitors and endothelin receptor antagonists should be started with caution and often in combination with diuretics to prevent pulmonary edema.