IL-8 Is Upregulated in the Tissue-Derived EVs of Odontogenic Keratocysts

Background: Interleukin 8 (IL-8) is a chemotactic cytokine released by various cells including leukocytes, endothelial cells, and epithelial cells. IL-8 has multiple functions in inflammation, tumour invasion, or angiogenesis. Human odontogenic cystic lesions are chronic and frequently inflamed. Tissue-derived extracellular vesicles (Ti-EVs) are widely present in various tissues and could more accurately reflect the characteristics of the primary tissue. However, the involvement of IL-8 in Ti-EVs of human odontogenic lesions is still unclear. This study aimed to explore the expression of IL-8 in Ti-EVs of human odontogenic lesions and the potential roles of Ti-EVs that carried IL-8.

Methods: Fresh tissue samples of dentigerous cyst (DC, n = 5) and odontogenic keratocyst (OKC, n = 5) were collected for Ti-EVs isolation. Ti-EVs were characterised by transmission electron microscopy and nano-flow cytometry analysis. The cytokine profile of Ti-EVs was explored by cytokine antibody array. The IL-8 expression was examined by immunochemical staining in tissue of odontogenic lesions (DC, n =12; OKC, n =28). Antioxidants (N-acetyl-L-cysteine and diphenyleneiodonium) were employed to treat HaCaT cells, and the expression of IL-8 was detected by enzyme-linked immunosorbent assay. The gene expression of MMP9 was explored by quantitative real-time polymerase chain reaction in co-culture system of fibroblasts of OKC with Ti-EVs.

Results: Compared with DC, the expression of IL-8 in Ti-EVs and fixed tissue specimens of OKC was markedly upregulated. The antioxidants decreased the expression level of IL-8 protein in the supernatant of HaCaT cells. The Ti-EVs treatment (10 μg/ml) of fibroblasts significantly induced the MMP9 mRNA expressions in OKC fibroblasts.

Conclusions: IL-8 was upregulated in Ti-EVs of OKC and might be involved in the tissue destruction of OKC.