Apigenin attenuates LPS-induced corneal inflammation by modulating NF-κB and JNK/ERK signaling pathways

Objective: To investigate the protective effects and molecular mechanisms of apigenin (API) on lipopolysaccharide (LPS)-induced corneal inflammation.

Methods: Immortalized human corneal epithelial cell line (HCECs) and primary human corneal epithelial cells (PHCECs) were used to establish LPS-induced inflammation models in vitro. IL-6 and IL-8 mRNA and protein levels were assessed by qRT-PCR and ELISA. Transcriptome Sequencing and KEGG/GO enrichment analyses were performed to identify key pathways. Western blotting evaluated the activation of MAPK (ERK, JNK, P38) and NF-κB (P65, IκBα) pathway proteins, and immunofluorescence was used to examine P65 nuclear translocation. Furthermore, following the establishment of an inflammation model via intrastromal LPS injection in mice, API was administered to assess its impact on ocular inflammation and pro-inflammatory cytokine expression.

Results: API significantly suppressed the expression and secretion of key pro-inflammatory mediators in LPS-stimulated corneal epithelial cells including IL-6, IL-8, and COX2. Transcriptomic analysis confirmed the MAPK and NF-κB pathways as critical components in API'a anti-inflammatory action. API inhibited the phosphorylation of key proteins in the MAPK-JNK/ERK and NF-κB signaling pathways, blocked the nuclear translocation of P65. In mice, API alleviated corneal edema and inflammatory cell infiltration and decreased IL-6 and TNF-α levels in corneal tissue.

Conclusion: API effectively attenuates LPS-induced corneal inflammation by inhibiting JNK/ERK and NF-κB signaling pathways and downstream effectors, thereby reducing the production of pro-inflammatory cytokines such as IL-6, IL-8, COX2, and TNF-α.

Apigenin; Corneal inflammation; JNK/ERK; LPS; NF-κB.