Tacrolimus exerts anti-inflammatory effects in moderate to severe dry eye through activation of autophagy-lysosomal pathway.

Abstract

This study aimed to investigate the therapeutic potential and anti-inflammatory mechanisms of tacrolimus (FK506) in moderate to severe dry eye by clinical, in vivo, and in vitro studies. We evaluated the effect of 0.1&#xa0;% FK506 versus 0.1&#xa0;% fluorometholone eye drops on patients with moderate to severe dry eye. Ocular surface disease index questionnaire (OSDI), tear breakup time (TBUT), corneal erosion, Schirmer's I test, and conjunctival impression cytology were measured at 2, 4, and 8 weeks. Tear samples from patients before and after FK506 treatment were subjected to proteomic analysis. The underlying mechanisms of FK506 were clarified using dry eye rat model and hypertonic-stimulated human corneal epithelial cells. Results demonstrated that FK506 showed transiently superior efficacy over fluorometholone in OSDI at week 2 (P&#xa0;=&#xa0;0.041) and TBUT at week 4 (P&#xa0;=&#xa0;0.001), despite both groups achieving significant improvements in all parameters from baseline to week 8 (P&#xa0;<&#xa0;0.001). Tear proteomics revealed FK506-mediated modulation of autophagy-lysosomal pathway. FK506 improved ocular surface damage, reduced TNF-&#x3b1; and IL-1&#x3b2;, and upregulated LC3B II, TFEB, and LAMP1 protein expression, accompanied by reduced P62 in the rat cornea. In vitro, FK506 suppressed pro-inflammatory cytokines via enhanced autophagic flux, promoted TFEB nuclear translocation, restored lysosomal structural and functional integrity, while inhibited mTOR phosphorylation. Knockdown of TFEB reversed the FK506-mediated benefits. Overall, FK506 alleviates the symptoms and signs of moderate to severe dry eye by suppressing the inflammatory response in corneal epithelial cells. This therapeutic effect is mediated through the activation of the TFEB-driven autophagy-lysosomal pathway.