β-Adrenergic Signaling Contributes to Circadian and Lipid Dysregulation in Meibomian Glands During Chronic Psychological Stress

Purpose: To investigate how chronic psychological stress alters circadian, immune, and lipid regulatory networks in meibomian glands (MGs) and to assess the efficacy of β-adrenergic blockade in mitigating these effects. Methods: Male C57BL/6J mice were exposed to daily 4-hour restraint stress for 14 days. Experimental groups included control, stress alone, stress with propranolol (a nonselective β-adrenergic receptor antagonist), and stress with metyrapone (a glucocorticoid synthesis inhibitor). MGs were collected at 3-hour intervals across a 24-hour period for bulk RNA sequencing. Additional analyses included single-cell RNA sequencing, untargeted lipidomics, and immunohistochemistry. Circulating levels of corticotropin-releasing hormone, adrenocorticotropic hormone, corticosterone, norepinephrine, and epinephrine were measured. Adrenal glands and superior cervical ganglia were examined to evaluate neuroendocrine activation. Results: Chronic stress activated both the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, leading to broad transcriptional reprogramming in MGs. Circadian gene expression became phase-dispersed, immune-related pathways were suppressed, and lipid profiles shifted toward elevated triglycerides and reduced phospholipid content. Propranolol, but not metyrapone, partially restored circadian rhythmicity, immune signaling, T-cell infiltration, and lipid composition. Increased proliferation of MG epithelial cells under stress was reduced by propranolol. β-Adrenergic receptors ADRB1 and ADRB2 were localized to MG epithelial subsets. Conclusions: Chronic psychological stress disrupts MG homeostasis through sympathetic overactivation, affecting circadian regulation, immune responses, and lipid metabolism. β-Adrenergic blockade partially reverses these changes, highlighting a potential therapeutic approach for stress-related evaporative dry eye.