Hypoxia-Driven Pulmonary Adaptation in the Yak: A Homeostatic Mechanism Mediated by Cell Adhesion Molecules

Cell adhesion molecules (CAMs) are key regulators of tissue structural integrity and functional coordination, yet their specific role in the adaptation of yak lung tissue to high-altitude hypoxia remains unelucidated. Thus, we employed transcriptomic sequencing (RNA-seq), molecular biology assays, and single-cell RNA-seq (scRNA-seq) to analyze the expression characteristics of CAMs in yak lung tissues at high and low altitudes. Trypsin or collagenase digestion showed higher cell counts in high-altitude yak lungs (p < 0.05). RNA-seq analysis revealed significant enrichment of differentially expressed genes (DEGs) in adhesion-related pathways. Inductively coupled plasma mass spectrometry detected elevated Ca²⁺ levels in high-altitude yak lungs (p < 0.05). Quantitative real-time PCR (qRT-PCR) detection of key genes from five major families of CAMs revealed the downregulation of cadherin and integrin family-related genes, and upregulation of immunoglobulin superfamily-related genes, in high-altitude yak lungs (p < 0.05), corroborated by immunohistochemical (IHC) staining. A 10× scRNA-seq revealed adhesion changes in 9 of 15 lung cell subpopulations, with differentially expressed CAMs involving integrins. This study demonstrates that yak lung tissue establishes a sophisticated adhesive homeostasis through differential CAMs regulation. This strategy optimizes pulmonary immune responses and energy allocation, ensures structural integrity and functional coordination, and thereby facilitates superior acclimatization to higher-altitude hypoxia.