PSVII-16 Recombinant bovine lactoferrin expressed in <i>Schizochytrium sp.</i> alleviates inflammation and oxidative damage in calf intestinal epithelial cells

Abstract This study aims to generate recombinant bovine lactoferrin (rbLF) by expressing it in Schizochytrium sp. (SZ) and evaluate its effects on calf intestinal epithelial cells (CIECs) exposed to lipopolysaccharide (LPS) or hydrogen peroxide-induced damage. The bovine lactoferrin expression cassette was transfected into Schizochytrium sp. via 18s rRNA gene recombination. Primary CIECs were utilized in this investigation, and the optimal dose of rbLF was evaluated by cell counting kit-8 assay after being treated with different concentrations of rbLF for 24 h. The optimal dose of rbLF was then used as a medium supplement before or after 24 h of 80 μg/mL LPS challenge or 4 h of 400 μM of hydrogen peroxide (H2O2) challenge. Cell viability, gene expression of tumor necrosis factor (TNF) -α, toll-like receptor (TLR) -4, interleukin (IL) -17A, zonula occludens-1 (ZO-1), and claudin-1, as well as protein levels of TNF-α, IL-17A, ZO-1, and claudin-1, were assessed to elucidate the preventive and therapeutic effects of rbLF. Data analysis was performed using SAS 9.4 by F-test, The statistical significance was declared at P &amp;lt; 0.05. Results indicate that rbLF demonstrated no cytotoxicity within the 50 to 1,000 μg/mL range on CIECs. Treatment with 175 μg/mL rbLF for 24 h increased cell viability, expression, and protein concentrations of ZO-1 and claudin following hydrogen peroxide challenge (P &amp;lt; 0.05). Moreover, rbLF pretreatment for 24 hours, despite decreasing cell viability after the H2O2 challenge, increased the expression and protein concentrations of ZO-1 and claudin-1 compared with non-rbLF-treated groups (P &amp;lt; 0.05). When used to prevent LPS-induced inflammation, rbLF enhanced the gene expression and protein concentrations of TNF-α, ZO-1, and claudin-1 compared with controls (P &amp;lt; 0.05). As a treatment for LPS-induced inflammation, rbLF decreased TLR4, TNF-α, and IL-17A expression levels (P &amp;lt; 0.05). These findings suggest that SZ-expressed rbLF is safe for calve intestinal cells and 175 μg/mL of rbLF may mitigate inflammation-induced intestinal barrier dysfunction.