Biogenic Synthesis of Novel Functionalized Selenium Nanoparticles by Lactobacillus casei ATCC 393 and Its Protective Effects on Intestinal Barrier Dysfunction Caused by Enterotoxigenic Escherichia coli K88

Abstract

Selenium (Se) is an essential element for human and animal health. Biogenic selenium nanoparticles (SeNPs) by microorganism possess unique physical and chemical properties and biological activities compared with inorganic Se and organic Se. The study was conducted to investigate the mainly biological activities of SeNPs by <i>Lactobacillus casei</i> ATCC 393 (<i>L. casei</i> 393). The results showed that <i>L. casei</i> 393 transformed sodium selenite to red SeNPs with the size of 50-80 nm, and accumulated them intracellularly. <i>L. casei</i> 393-SeNPs promoted the growth and proliferation of porcine intestinal epithelial cells (IPEC-J2), human colonic epithelial cells (NCM460), and human acute monocytic leukemia cell (THP-1)-derived macrophagocyte. <i>L. casei</i> 393-SeNPs significantly inhibited the growth of human liver tumor cell line-HepG2, and alleviated diquat-induced IPEC-J2 oxidative damage. Moreover, <i>in vivo</i> and <i>in vitro</i> experimental results showed that administration with <i>L. casei</i> 393-SeNPs protected against Enterotoxigenic <i>Escherichia coli</i> K88 (ETEC K88)-caused intestinal barrier dysfunction. ETEC K88 infection-associated oxidative stress (glutathione peroxidase activity, total superoxide dismutase activity, total antioxidant capacity, and malondialdehyde) was ameliorated in <i>L. casei</i> 393-SeNPs-treated mice. These findings suggest that <i>L. casei</i> 393-SeNPs with no cytotoxicity play a key role in maintaining intestinal epithelial integrity and intestinal microflora balance in response to oxidative stress and infection.