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Thymol Protects against Aspergillus Fumigatus Keratitis by Inhibiting the LOX-1/IL-1β Signaling Pathway

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Abstract

Objective

To explore the anti-inflammatory effects and mechanisms of action of thymol in Aspergillus fumigatus (A. fumigatus) keratitis.

Methods

The minimum inhibitory concentration of thymol against A. fumigatus was detected. To characterize the anti-inflammatory effects of thymol, mouse corneas and human corneal epithelial cells were pretreated with thymol or dimethyl sulfoxide (DMSO) before infection with A. fumigatus spores. Slit-lamp microscopy, immunohistochemistry, myeloperoxidase detection, quantitative real-time polymerase chain reaction, and Western blotting were used to assess infection. Neutrophil and macrophage recruitment, in addition to the secretion of LOX-1 and IL-1β, were quantified to evaluate the relative contribution of thymol to the inflammatory response.

Results

We confirmed that the growth of A. fumigatus was directly inhibited by thymol. In contrast with the DMSO group, there was a lower degree of inflammation in the mouse corneas of the thymol-pretreated group. This was characterized by significantly lower clinical scores, less inflammatory cell infiltration, and lower expression of LOX-1 and IL-1β. Similarly, in vitro experiments indicated that the production of LOX-1 and IL-1β was significantly inhibited after thymol treatment, in contrast with the DMSO-pretreated group.

Conclusion

Our findings demonstrate that thymol exerted a direct fungistatic activity on A. fumigatus. Furthermore, thymol played a protective role in fungal keratitis by inhibiting LOX-1/IL-1β signaling pathway and reducing the recruitment of neutrophils and macrophages.

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Author notes

  1. These authors contributed equally to this work.

Authors and Affiliations

  1. Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao, 266003, China

    Li-mei Wang, Hua Yang, Hai-jing Yan, Yun-xiao Wang, Sha-sha Xue, Lin Li, Le-yu Lyu & Cheng-ye Che

  2. Department of Otorhinolaryngology-Head and Neck Surgery, the Affiliated Hospital of Qingdao University, Qingdao, 266003, China

    Rui-feng Ge

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  1. Li-mei Wang
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  2. Hua Yang
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Correspondence to Cheng-ye Che.

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Conflict of Interest Statement

The authors have no conflicts of interest.

This project was supported by grants from the National Natural Science Foundation of China (No. 82171019), Natural Science Foundation of Shandong Province (No. ZR2021MH368), Traditional Chinese Medicine Research Project of Qingdao (No. 2020-zyy055) and Shandong Qingdao Outstanding Health Professional Development Fund.

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Wang, Lm., Yang, H., Yan, Hj. et al. Thymol Protects against Aspergillus Fumigatus Keratitis by Inhibiting the LOX-1/IL-1β Signaling Pathway. CURR MED SCI 42, 620–628 (2022). https://doi.org/10.1007/s11596-022-2512-9

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  • DOI: https://doi.org/10.1007/s11596-022-2512-9

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