Liquiritin Alleviates Inflammation in Lipopolysaccharide-Induced Human Corneal Epithelial Cells

Abstract

Purpose

This research was designed to elucidate the anti-inflammatory impacts of liquiritin on lipopolysaccharide (LPS)-activated human corneal epithelial cells (HCECs).

Methods

The Cell Counting kit-8 (CCK-8) assay was adopted to assess cell viability. The enzyme-linked immunosorbent assay (ELISA) was used to detect the secretion levels of the proinflammatory cytokines IL-6, IL-8, and TNF-α. Transcriptome analysis was conducted to identify the genes that exhibited differential expression between different treatment. The model group included cells treated with LPS (10 µg/mL), the treatment group comprised cells treated with liquiritin (80 µM) and LPS (10 µg/mL), and the control group consisted of untreated cells. To further validate the expression levels of the selected genes, including CSF2, CXCL1, CXCL2, CXCL8, IL1A, IL1B, IL24, IL6, and LTB, quantitative real-time PCR was performed. The expression of proteins related to the Akt/NF-κB signaling pathway was assessed through western blot analysis. NF-κB nuclear translocation was evaluated through immunofluorescence staining.

Results

The secretion of IL-6, IL-8, and TNF-α in LPS-induced HCECs was significantly downregulated by liquiritin. Based on the transcriptome analysis, the mRNA expression of pro-inflammatory cytokines, namely IL-6, IL-8, IL-1β, IL-24, TNF-α, and IL-1α was overproduced by LPS stimulation, and suppressed after liquiritin treatment. Furthermore, the Western blot results revealed a remarkable reduction in the phosphorylation degrees of NF-κB p65, IκB, and Akt upon treatment with liquiritin. Additionally, immunofluorescence analysis confirmed liquiritin’s inhibition of LPS-induced p65 nuclear translocation.

Conclusions

Collectively, these findings imply that liquiritin suppresses the expression of proinflammatory cytokines, and the anti-inflammatory impacts of liquiritin may be caused by its repression of the Akt/NF-κB signaling pathway in LPS-induced HCECs. These data indicate that liquiritin could provide a potential therapeutic application for inflammation-associated corneal diseases.

Keywords:

• Liquiritin
• inflammation
• human corneal epithelial cells
• transcriptome analysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding authors, [LF and XC], upon reasonable request.

Correction Statement

This article has been republished with minor change. This change do not impact the academic content of the article.

Additional information

Funding

This work was supported by Zhejiang Provincial Pharmaceutical Regulatory System Technology Program (No. 2022031); Zhejiang Provincial Natural Science Foundation of China (No. LGD22C040004).