Journal of Jilin University(Medicine Edition) ›› 2021, Vol. 47 ›› Issue (2): 315-322.doi: 10.13481/j.1671-587X.20210209

• Research in basic medicine • Previous Articles     Next Articles

Regulatory effect of luteolin on Aspergillus fumigatus keratitis through TLR4/MyD88 signaling pathway in rats

Shurong ZHANG(),Qiying ZHANG   

  1. Department of Ophthalmology,Affiliated Third Hospital,Qiqihar Medical College,Qiqihar 161000,China
  • Received:2020-05-08 Online:2021-03-28 Published:2021-03-25
  • Contact: Shurong ZHANG E-mail:hk122221@163.com

Abstract:

Objective: To investigate the regulatory effects of luteolin on the Aspergillus fumigatus keratitis (AFK) through Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88(MyD88) signaling pathway in the rats, and to elucidate its mechanism of inhibiting AFK inflammatory response.

Methods

Fifteen rats were randomly selected from 100 SD rats as sham operation group [without injection of Aspergillus funmigatus (AF) spore suspension], and the other 85 rats were injected with spore suspension of AF to establish the AFK models. Seventy-two rats were successfully established and randomly divided into model group (14 rats), low dose of luteolin group (14 rats), medium dose of luteolin group (14 rats), high dose of luteolin group (15 rats), LPS + luteolin group (15 rats). The rats in low, medium and high doses of luteolin groups were given local eye drop of 50 μL luteolin with concentrations of 5, 10 and 20 g·L-1;the rats in sham operation group and model group were given the same amount of 1% DMSO solution;the rats in LPS + luteolin group were given 20 g·L-1 luteolin solution and 1.0 μg LPS solution for local eye drops;lasted for 7 d. The general changes of cornea of the rats in various groups were observed and the cornea inflammation index was evaluated. The corneal tissue samples were obtained, and the pathomorphology of cornea tissue was observed by HE staining method. The levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-12 (IL-12) in cornea tissue of the rats in various groups were detected by enzyme-linked immunosorbent assay (ELISA). The expression levels of TLR4, MyD88, and nuclear transcription factor-κB (NF-κB) proteins in cornea tissue of the rats in various groups were detected by Western blotting method.

Results

The cornea tissue epithelium of the rats in sham operation group was intact without inflammatory cell infiltration.The cornea of rats in model group and LPS + luteolin group showed white dense ulcers, edema and dull surface, the iris was not visible, and the area of ulcers in LPS + luteolin group was larger. In low, medium and high doses of luteolin groups, the areas of ulcer focus were gradually decreased and the lesions were alleviated. The HE staining results showed that the collagen fibers were swollen and disordered in model group and LPS + luteolin group, a large number of inflammatory cells were infiltrated, and the above changes were alleviated in low, middle and high doses of luteolin groups, especially in high dose of luteolin group. Compared with model group, the cornea inflammation index, the levels of IL-1β, TNF-α, IL-12 and the experssion levels of TLR4, MyD88, NF-κB proteins in corneal tissue in low, medium and high doses of luteolin groups were decreased (P<0.05).The above indexes of the rats in LPS + luteolin group were higher than those in model group and low, medium and high doses of luteolin groups (P<0.05).

Conclusion

Luteolin has a therapeutic effect in the AFK rats and can effectively inhibit corneal inflammation, and its mechanism may be ralated to inhibiting the expressions of TLR4 / MyD88 signaling pathway-related proteins and its down-stream inflammatory factors.

Key words: Aspergillus fumigatus keratitis, luteolin, Toll-like receptor 4, myeloid cell differentiation factor 88, inflammatory factor

CLC Number: 

  • R772.21