Gingival mesenchymal stem cell-derived exosomes ameliorate human adult keratinocyte transformed cell line inflammation and apoptosis via the TLR4/NF-κB pathway.

OBJECTIVE

This study sought to elucidate the regulatory mechanisms of exosomes derived from gingival mesenchymal stem cells (GMSC-Exo) in the context of inflammation associated with oral lichen planus (OLP).

DESIGN

An in vitro OLP inflammatory model was established by stimulating the Human Adult Keratinocyte Transformed Cell Line (Hacat) with lipopolysaccharide (LPS). The cellular uptake of GMSC-Exo was detected by immunofluorescence. Enzyme-linked immunosorbent assay (ELISA) was employed to assess the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10). Cell viability and apoptosis were measured by Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. The mRNA levels of Toll-like receptor 4 (TLR4) were determined via reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and the protein expression levels of TLR4, phosphorylated nuclear factor kappa B subunit p65 (p-P65), P65, phosphorylated IκBα (p-IκBα), and IκBα were further validated by Western Blot.

RESULTS

LPS stimulation significantly increased the secretion of pro-inflammatory cytokines (TNF-α, IL-6), decreased the production of the anti-inflammatory cytokine IL-10, and promoted Hacat cell apoptosis while impairing cell viability. Notably, administration of GMSC-Exo effectively alleviated these LPS-induced effects. Mechanistically, GMSC-Exo suppressed LPS-induced TLR4 overexpression and blocked downstream nuclear factor kappa B (NF-κB) signaling activation, as evidenced by decreased phosphorylation of IκBα and P65.

CONCLUSIONS

GMSC-Exo alleviates LPS-induced inflammation and apoptosis in Hacat cells by downregulating the TLR4/NF-κB signaling pathway. Our findings offer novel insights and potential therapeutic strategies for treating OLP.