Characteristics linking ischemia-reperfusion to chronic lung allograft dysfunction in lung transplantation: A single-cell bioinformatics analysis.

BACKGROUNDLung transplantation offers a life-saving procedure to patients with end-stage lung diseases with 85-89 % one year and 60 % five-year survival rates. Lung transplants are complicated by early ischemia/reperfusion injury (IRI) and late chronic lung allograft dysfunction (CLAD). However, the cellular and molecular links between IRI and CLAD remain unclear.

MATERIALS AND METHODSWe integrated single-cell RNA-seq results from GSE220797 and GSE224210 data sets. After quality filtering, we performed Louvain clustering and UMAP visualization. We applied Augur method to prioritize cell populations by transcriptional responsiveness to IRI and CLAD. We also performed dynamic trajectory analyses to map pseudotemporal transitions. Pathway activity was characterized by differential expression analysis and module scoring. Intercellular communication was assessed using CellChat and MEBOCOST analyses. Regulon inference was performed with pySCENIC analysis.

RESULTSOverall, epithelial cells showed progressive metabolic suppression and activation of cuproptosis, a programmed cell death (PCD) triggered by excessive copper accumulation within cells. Club cells, found in the small airways of the lungs, exhibited developmental plasticity and predictive potential across IRI and CLAD conditions. Among myeloid populations, M1 proinflammatory (AM_M1TM) macrophages underwent macrophage-to-myofibroblast transition (MMT) and produced excessive extracellular matrix (ECM) supporting a network of proteins surrounding cells. Metabolite and cell-cell communication analyses revealed declining macrophage/epithelial metabolic crosstalk and differential signaling flux from normal through IRI to CLAD transition.

CONCLUSIONSThe integrated single-cell atlas delineates interaction of multiple cells and their signaling pathways linking IRI to CLAD processes. These findings require further verification through studies in animal models and clinical samples.