Plin2 Coordinates Immune and Metabolic Reprogramming in Lacrimal Gland Aging.

Purpose: Aging impairs lacrimal gland function, contributing to dry eye syndrome and reduced quality of life. This study aimed to identify core molecular regulators of lacrimal gland aging and delineate their roles in immune imbalance and metabolic dysfunction.

Methods: Bulk transcriptomic profiling and single-cell RNA sequencing (scRNA-seq) were performed on lacrimal glands from young and aged C57BL/6 mice. Differentially expressed genes (DEGs) were screened, followed by machine learning-based feature selection using least absolute shrinkage and selection operator regression and support vector machine-recursive feature elimination. Immune cell composition was inferred using the CIBERSORT algorithm, and functional enrichment (gene ontology, Kyoto Encyclopedia of Genes and Genomes, and gene set enrichment analysis) and cell-type-resolved spatial analyses were conducted to elucidate aging-associated pathways.

Results: Among 659 DEGs, Perilipin-2 (Plin2) emerged as the sole hub gene identified by both algorithms, with perfect classification performance (area under the curve = 1.00). Aging was associated with increased infiltration of pro-inflammatory cells (naïve B cells, M1 macrophages) and depletion of anti-inflammatory subsets (plasma cells, M2 macrophages). Plin2 expression exhibited a significant inverse association with pro-senescent immune populations and a positive correlation with regulatory immune cells. Functional analyses linked Plin2 to T/B cell receptor signaling, cytokine interaction, and ribosomal biosynthesis. scRNA-seq revealed Plin2 downregulation in fibroblasts and Mono/Mφ/DC subsets in aged glands (P < 0.001), indicating stromal-immune dysfunction.

Conclusions: Our study identifies Plin2 as a master regulator of immune-metabolic aging in the lacrimal gland. Its decline accelerates inflammaging and metabolic reprogramming, contributing to tissue atrophy and tear deficiency. Plin2 represents a promising candidate biomarker and potential therapeutic target for age-related ocular diseases.