Lactoferrin attenuates lipopolysaccharide-stimulated inflammatory responses and barrier impairment through the modulation of NF-κB/MAPK/Nrf2 pathways in IPEC-J2 cells

Lactoferrin (LF) plays critical roles in various physiological processes. However, its protective effects on small intestinal epithelial cells remain poorly understood. This study aimed to investigate its protective effects and underlying mechanisms in vitro on lipopolysaccharide (LPS)-challenged intestinal porcine epithelial cells (IPEC-J2 cells). The IPEC-J2 cells were treated with or without LPS and LF for 24 h and analyzed using various assays. The results indicated that the LPS treatment induced the secretion of pro-inflammatory cytokines [interleukin (IL)-1β, IL-8, and TNF-α], increased cell permeability, and enhanced reactive oxygen species (ROS) production. The LF treatment decreased the secretion and gene expression of IL-1β and downregulated the phosphorylation levels of NF-κB, IκB, P38, and ERK1/2 in LPS-challenged cells. Moreover, the LF treatment decreased cell permeability, enhanced the expression of claudin-1 protein, and inhibited the expression of the myosin light-chain kinase (MLCK) protein in LPS-challenged cells. It also reduced the ROS and MDA production as well as upregulated the GSH-Px activity and the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) protein. Taken together, these results suggested that LF alleviated the LPS-induced cellular inflammation through the attenuation of nuclear factor kappa B (NF-κB)/mitogen-activated protein kinase (MAPK) pathways, maintaining cellular barrier integrity and mitigating oxidative stress.