The In Vitro Protective Role of Bovine Lactoferrin on Intestinal Epithelial Barrier

Abstract

The intestinal epithelial barrier plays a key protective role in the gut lumen. Bovine lactoferrin (bLF) has been reported to improve the intestinal epithelial barrier function, but its impact on tight junction (TJ) proteins has been rarely described. Human intestinal epithelial crypt cells (HIECs) were more similar to those in the human small intestine, compared with the well-established Caco-2 cells. Accordingly, both HIECs and Caco-2 cells were investigated in this study to determine the effects of bioactive protein bLF on their growth promotion and intestinal barrier function. The results showed that bLF promoted cell growth and arrested cell-cycle progression at the G2/M-phase. Moreover, bLF decreased paracellular permeability and increased alkaline phosphatase activity and transepithelial electrical resistance, strengthening barrier function. Immunofluorescence, western blot and quantitative real-time polymerase chain reaction revealed that bLF significantly increased the expression of three tight junction proteins—claudin-1, occludin, and ZO-1—at both the mRNA and protein levels, and consequently strengthened the barrier function of the two cell models. bLF in general showed higher activity in Caco-2 cells, however, HIECs also exhibited desired responses to barrier function. Therefore, bLF may be incorporated into functional foods for treatment of inflammatory bowel diseases which are caused by loss of barrier integrity.

Bovine Colostrum: Its Constituents and Uses

“…Lactoferrin is an iron binding glycoprotein (80 kDa) present in human colostrum and BC, although levels in BC are only about 10% of human values [ 58 , 59 ]. Lactoferrin induces multiple effects, including enhancing iron absorption as well as possessing antimicrobial activity [ 60 , 61 ], binding lipopolysaccharide, immune-modulating, and stimulating growth of intestinal epithelial cells and fibroblasts [ 62 ]. These findings suggest lactoferrin in BC may be relevant for the regulation of gut growth in neonates.…”

Lactoferrin in Aseptic and Septic Inflammation

“…These pathologies are characterized by a loss of barrier integrity and inflammatory processes [203]. Intestinal barrier integrity is a key feature in the health of humans, especially for newborns, because the neonatal immature gastrointestinal system and immune system are still developing [204].…”

“…The protective function of bLf in aseptic IBD has been reported in some in vitro and in vivo approaches. In a recent in vitro study, Zhao et al [203] have demonstrated that bLf triggers the up-regulation of claudin-1, occludin, and zonula occludens-1 expression, which, in turn, strengthen the barrier function of intestinal cells. Interestingly, the decrease of TNF-α mRNA levels, in a bLf dose-dependent manner (50 µg/mL and 100 µg/mL), and the consequent inhibition of NF-κB signal pathway were also observed [203].…”

“…In a recent in vitro study, Zhao et al [203] have demonstrated that bLf triggers the up-regulation of claudin-1, occludin, and zonula occludens-1 expression, which, in turn, strengthen the barrier function of intestinal cells. Interestingly, the decrease of TNF-α mRNA levels, in a bLf dose-dependent manner (50 µg/mL and 100 µg/mL), and the consequent inhibition of NF-κB signal pathway were also observed [203]. Concerning in vivo studies, Togawa et al [217] demonstrated that in dextran sulfate sodium-induced colitis in rats, mimicking human IBD, the oral administration of Lf (200 mg/kg for 7 days) decreased inflammation and myeloperoxidase activity used as a biochemical marker of neutrophil infiltration.…”

Lactoferrin in the Prevention and Treatment of Intestinal Inflammatory Pathologies Associated with Colorectal Cancer Development

“…The protective function of bLf towards intestinal barrier dysfunctions has been reported in two in vitro studies [ 236 , 237 ]. The study by Hering and colleagues demonstrated that bLf was able to: (i) restore TJ morphometry and inhibit apoptosis in TNF-α challenged human epithelial cell models; (ii) counteract trans-epithelial resistance drop and claudin-8 down-regulation in Y. enterocolitica infected human epithelial cell models [ 236 ].…”