DHCR24 Deficiency Drives Age-Related Meibomian Gland Dysfunction by Regulating Lipid Metabolic Imbalance and Cytosolic mtDNA-Induced cGAS-STING Activation.

Dysregulated lipid metabolism and chronic inflammation are hallmarks of aging, yet their interplay in age-related tissue disorders remains poorly defined. In the ocular surface, age-related meibomian gland dysfunction (ARMGD) is highly prevalent but mechanistically unclear, leading to significant visual impairment without targeted therapies. To identify key molecular drivers of ARMGD, we performed integrated multi-omics screening of aging mouse meibomian glands (MGs) and identified DHCR24, a key cholesterol metabolism enzyme, as a critical regulator of gland homeostasis. Single-cell sequencing identified age-associated downregulation of Dhcr24 predominantly in meibocytes. Based on this finding, we generated a meibocyte-specific Dhcr24 knockout (cKO) model, which exhibited typical ARMGD pathology including glandular atrophy, disrupted lipid homeostasis, and inflammatory activation. Further in vitro studies using SZ95 sebocytes demonstrated that DHCR24 deficiency induces mitochondrial dysfunction and cytosolic mitochondrial DNA (mtDNA) leakage, triggering cGAS/STING-dependent inflammatory senescence. Notably, AAV-mediated restoration of DHCR24 in mice reversed age-related gland pathology. Our findings establish DHCR24 as a dual-target regulator that maintains cholesterol metabolic homeostasis while suppressing mtDNA-driven inflammation via the cGAS-STING pathway, highlighting its therapeutic potential for ARMGD and related disorders characterized by lipid-inflammatory imbalance.