Combined use of hydrogen-rich water and enzyme-digested edible bird's nest improves PMA/LPS-impaired wound healing in human inflammatory gingival tissue equivalents

Abstract

Gingival wound healing plays a critical role in maintaining oral health. However, this process can be delayed by oxidative stress and excessive inflammatory responses. In this study, we established a human inflammatory gingival tissue equivalent (iGTE) to investigate the inhibitory effects of hydrogen-rich water (HW), enzyme-digested edible bird's nest (EBND) and sialic acid (SA) on PMA (an inducer of oxidative free radicals)- and LPS (an inflammatory stimulus)-impaired wound healing. The iGTE was constructed by human gingival fibroblasts (hGFs), keratinocytes and macrophages under three-dimensional conditions. Wounds in the iGTE and hGF/keratinocyte monolayers were created by mechanical injury. Tissues and cells were pretreated with HW, EBND, and SA, and then exposed to the inflammatory and oxidative environment induced by PMA (10 ng/mL) and LPS (250 ng/mL). The inflammatory cytokines IL-6 and IL-8 were quantitatively analyzed by ELISA. Histopathological image analysis was performed by HE and immunofluorescence staining. In the iGTE, PMA/LPS significantly reduced the epithelial thickness while causing a decrease in K8/18, E-cadherin, laminin and elastin expression and an increase in COX-2 expression along with ulcer-like lesions. In mechanically scratched hGFs and keratinocyte monolayers, PMA/LPS significantly impaired wound healing, and promoted the secretion of IL-6 and IL-8. Pretreatment of HW, EBND, and SA significantly suppressed PMA/LPS-induced wound healing delay and inflammatory responses in cell monolayers, as well as in the iGTE. Remarkably, the combined use of HW and EBND exhibited particularly robust results. Combined use of HW and EBND may be applied for the prevention and treatment of wound healing delay.

Keywords: Edible bird’s nest; Gingival tissue engineering; Hydrogen rich water; Inflammation; Wound healing delay.