This is a mechanism module, not a specific disease. Disorder entries reference individual nodes via conforms_to (e.g., "pulmonary_vascular_remodeling#Obstructive Pulmonary Vascular Remodeling"). The module defines the expected pathophysiology structure; conforming nodes in disorder files should include the corresponding cell types, biological processes, and causal edges, specialized to their disease context. Key disorder-specific substitutions: heritable PAH substitutes a BMPR2 loss-of-function lesion at the trigger node; idiopathic PAH substitutes acquired endothelial injury; connective-tissue-disease-associated PAH (e.g., systemic sclerosis) substitutes immune/inflammatory endothelial injury. The pulmonary artery endothelial cell and pulmonary artery smooth muscle cell are the conserved central cell types.
Pulmonary Endothelial Dysfunction and Impaired BMP Signaling
trigger
The initiating lesion is injury to and dysfunction of pulmonary arterial endothelial cells, with impaired bone morphogenetic protein (BMP) signaling (loss-of-function BMPR2 mutations in heritable PAH, acquired suppression in idiopathic and associated PAH). Dysfunctional endothelium loses its ability to produce vasodilatory mediators such as nitric oxide and prostacyclin while favoring vasoconstrictors such as endothelin-1, and undergoes hyperproliferation with early apoptosis followed by enrichment of apoptosis-resistant cells. This endothelial trigger generalizes across heritable, idiopathic, and connective-tissue-disease-associated PAH.
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Pulmonary Artery Smooth Muscle Cell Proliferation and Vasoconstriction
Show evidence (2 references)
"Compelling evidence from animal models suggests endothelial cell dysfunction is a key initial trigger of pulmonary vascular remodeling, which is characterised by hyperproliferation and early apoptosis followed by enrichment of apoptosis-resistant populations. Dysfunctional pulmonary arterial..."
Establishes endothelial dysfunction as the key initial trigger of pulmonary vascular remodeling and links loss of vasodilatory mediators to downstream smooth muscle responses. Evidence source is OTHER because this is a review synthesizing animal-model and human data.
"Although mutation in the bone morphogenetic protein receptor 2 (BMPR2) gene has been identified as the main genetic cause of PAH, the underlying pathways involving the pathophysiology of PAH are complex and still not fully understood. Endothelial dysfunction has been observed in PAH development..."
Ties impaired BMPR2 (BMP receptor) signaling to endothelial dysfunction as the central conserved trigger across PAH. Evidence source is OTHER because this is a review article.
Pulmonary Artery Smooth Muscle Cell Proliferation and Vasoconstriction
amplifier
Paracrine signals from the dysfunctional endothelium drive a cancer-like pro-proliferative, anti-apoptotic switch in pulmonary artery smooth muscle cells (PASMCs), together with sustained vasoconstriction. PASMCs acquire migratory capacity and resistance to apoptosis, increasing medial cellularity. This amplifying step is conserved across PAH subtypes regardless of the specific initiating endothelial injury.
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Obstructive Pulmonary Vascular Remodeling
Show evidence (2 references)
"Finally, EC signalling promotes proliferative and antiapoptotic PAH-PASMC phenotypes, which acquire migratory capacities, resulting in increased vascular wall thickness and muscularization of small pulmonary arterioles."
Directly describes the endothelium-driven proliferative and anti-apoptotic PASMC phenotype that thickens the vascular wall, the conserved amplifying step. Evidence source is OTHER because this is a review article.
"Underlying or contributing to the development of these lesions is hypertrophy, proliferation, migration, and resistance to apoptosis of medial cells and this article is concerned with the cellular and molecular mechanisms of these processes."
Establishes proliferation and resistance to apoptosis of medial (smooth muscle) cells as the cellular basis of the remodeling lesions. Evidence source is OTHER because this is a comprehensive physiology review.
Obstructive Pulmonary Vascular Remodeling
central effector
Sustained PASMC proliferation, neointima formation, and endothelial dysregulation remodel the pulmonary arterial wall, producing medial and adventitial hypertrophy, muscularization of previously nonmuscular peripheral arteries, and intimal and plexiform lesions that obliterate the lumen of small pulmonary arteries. This structural obstruction is the central effector of the module and is conserved across PAH subtypes.
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Increased Pulmonary Vascular Resistance
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"Pulmonary vascular remodeling is characterized by adventitial and medial hypertrophy due to fibroblast and smooth muscle cell proliferation, neointimal proliferation, intimal, and plexiform lesions that obliterate the lumen, muscularization of precapillary arterioles, and in situ thrombosis."
Directly describes the conserved obstructive remodeling lesions (medial hypertrophy, plexiform lesions, lumen obliteration). Evidence source is OTHER because this is a comprehensive physiology review.
"In PAH, the pulmonary vasculature is dynamically obstructed by vasoconstriction, structurally obstructed by adverse vascular remodeling, and pathologically non-compliant as a result of vascular fibrosis and stiffening."
Confirms that adverse vascular remodeling structurally obstructs the pulmonary vasculature, the central effector of the module. Evidence source is OTHER because this is a review.
Increased Pulmonary Vascular Resistance
effector
Structural obstruction and sustained vasoconstriction of the small pulmonary arteries increase pulmonary vascular resistance. The combination of dynamic (vasoconstrictive) and fixed (remodeling) obstruction raises the resistance the right ventricle must pump against.
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Pulmonary Arterial Hypertension
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"Pulmonary hypertension is a multifactorial disease characterized by sustained elevation of pulmonary vascular resistance (PVR) and pulmonary arterial pressure (PAP). Central to the pathobiology of this disease is the process of vascular remodelling."
Directly ties vascular remodeling to sustained elevation of pulmonary vascular resistance and pulmonary arterial pressure. Evidence source is OTHER because this is a comprehensive physiology review.
Pulmonary Arterial Hypertension
consequence
The convergent consequence is a sustained elevation of pulmonary arterial pressure. The increased resistance imposes a chronic pressure overload on the right ventricle, causing right ventricular hypertrophy and, in many patients, maladaptive remodeling that progresses to right ventricular failure and premature death. This is the named clinical phenotype (HP:0002092; MONDO:0005149).
Show evidence (2 references)
"Obstructive pulmonary vascular remodeling in PAH increases right ventricular afterload causing right ventricular hypertrophy. In some patients, maladaptive changes in the right ventricle, including ischemia and fibrosis, reduce right ventricular function and cause right ventricular failure."
Directly states that obstructive remodeling raises right ventricular afterload, causing hypertrophy and ultimately right ventricular failure, the defining consequence of the module. Evidence source is OTHER because this is a review.
"Disease pathogenesis is driven by progressive remodeling of peripheral pulmonary arteries, caused by the excessive proliferation of vascular wall cells, including endothelial cells, smooth muscle cells and fibroblasts, and perivascular inflammation."
Summarizes the whole conserved chain, attributing PAH pathogenesis to progressive pulmonary artery remodeling driven by excessive vascular-wall cell proliferation. Evidence source is OTHER because this is a review.