Mechanisms Underlying Altitude-Induced and Group 3 Pulmonary Hypertension

Pulmonary hypertension is a progressive and life-threatening disorder affecting approximately 1% of the global population, with increasing prevalence among elderly individuals. Although it most commonly arises as a complication of chronic cardiac or pulmonary diseases, it may also develop in otherwise healthy individuals exposed to chronic hypoxia at high altitude. In this setting, sustained alveolar hypoxia triggers pulmonary vasoconstriction and vascular remodeling, key processes driving the elevation of pulmonary arterial pressure and highlighting the critical role of environmental stressors in disease pathogenesis. In this review, we examine the molecular mechanisms underlying the hypoxia-pulmonary hypertension axis, focusing on the complex and interconnected signaling networks involving redox imbalance, PI3K-Akt signaling, Na⁺/H⁺ exchange, nitric oxide bioavailability, autophagy, mitochondrial dynamics and mitophagy, metabolic reprogramming, inflammation, adventitial remodeling with particular emphasis on pulmonary arterial adventitial fibroblasts, and erythropoietin signaling. We also discuss current knowledge gaps and emerging therapeutic opportunities that may arise from a deeper understanding of these pathways. Collectively, while many of the signaling mechanisms implicated in hypoxia-induced pulmonary hypertension offer therapeutic promise, none have yet proven fully translatable, underscoring the multifactorial and tightly integrated nature of this disease.