Abstract
AIM: To investigate the effects of a Chinese medicine formula "Qingxuan Runmu Yin" (QRY) on ocular surface inflammation in a rat model of dry eye, and its mechanism via the toll-like receptor 4 (TLR4)/transforming growth factor kinase 1 (TAK1)/p38 mitogen-activated protein kinase (p38MAPK) signaling pathway. METHODS: Seventy-two Sprague-Dawley rats were randomly divided into six groups (n=12 each): the control group, model group, 3 groups of QRY (with low-, medium-, and high-doses), and SB203580 group. Dry eye was induced using benzalkonium chloride. Schirmer's test (SIT) and corneal fluorescein staining (CFS) were performed every 14d throughout the experiment. Histopathological changes in corneal and conjunctival tissues were observed using hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) staining. Protein expression levels of key inflammatory markers and signaling pathway targets were assessed via immunohistochemistry, ELISA, and Western blotting. RESULTS: Compared to the control group, the model group showed significant reductions in SIT and increases in CFS scores, alongside structural disorganization of corneal/conjunctival tissues, decreased conjunctival goblet cell (CGC) numbers, and elevated expression of inflammatory markers [interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase-9 (MMP9)] and pathway proteins (TLR4, p-TAK1, p-p38MAPK; P<0.05). Treatment with QRY (low, medium, and high doses) and SB203580 significantly improved SIT scores, reduced CFS scores, restored corneoconjunctival structure, increased CGC numbers, and decreased expression levels of IL-1β, IL-6, TNF-α, MMP9, TLR4, p-TAK1, and p-p38MAPK proteins compared to the model group (P<0.05). CONCLUSION: QRY may alleviate ocular surface inflammation associated with dry eye by inhibiting the TLR4/TAK1/p38MAPK signaling pathway, highlighting its potential therapeutic efficacy for dry eye.