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

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.

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.

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.

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.