The Use of Polysaccharide AOP30 from the Rhizome of Alpinia officinarum Hance to Alleviate Lipopolysaccharide-Induced Intestinal Epithelial Barrier Dysfunction and Inflammation via the TLR4/NfκB Signaling Pathway in Caco-2 Cell Monolayers

Abstract

Alpinia officinarum Hance is rich in carbohydrates and is flavored by natives. The polysaccharide fraction 30 is purified from the rhizome of A. officinarum Hance (AOP30) and shows excellent immunoregulatory ability when administered to regulate immunity. However, the effect of AOP30 on the intestinal epithelial barrier is not well understood. Therefore, the aim of this study is to investigate the protective effect of AOP30 on the intestinal epithelial barrier using a lipopolysaccharide (LPS)-induced intestinal epithelial barrier dysfunction model and further explore its underlying mechanisms. Cytotoxicity, transepithelial electrical resistance (TEER) values, and Fluorescein isothiocyanate (FITC)–dextran flux are measured. Simultaneously, the protein and mRNA levels of tight junction (TJ) proteins, including zonula occludens-1 (ZO-1), Occludin, and Claudin-1, are determined using Western blotting and reverse-transcription quantitative polymerase chain reaction methods, respectively. The results indicate that AOP30 restores the LPS-induced decrease in the TEER value and cell viability. Furthermore, it increases the mRNA and protein expression of ZO-1, Occludin, and Claudin-1. Notably, ZO-1 is the primary tight junction protein altered in response to LPS-induced intestinal epithelial dysfunction. Additionally, AOP30 downregulates the production of TNFα via the Toll-like receptor 4 (TLR4)/NF-κB signaling pathway. Collectively, the findings of this study indicate that AOP30 can be developed as a functional food ingredient or natural therapeutic agent for addressing intestinal epithelial barrier dysfunction. It sheds light on the role of AOP30 in improving intestinal epithelial function.