Whey protein hydrolysates decrease IL-8 secretion in lipopolysaccharide (LPS)-stimulated respiratory epithelial cells by affecting LPS binding to Toll-like receptor 4

Abstract

Whey proteins (WP) exert anti-inflammatory and antioxidant effects. Hyperbaric pressurisation of whey increases its digestibility and changes the spectrum of peptides released during digestion. We have shown that dietary supplementation with pressurised whey improves nutritional status and systemic inflammation in patients with cystic fibrosis (CF). Both clinical indices are largely affected by airway processes, to which respiratory epithelial cells actively contribute. Here, we tested whether peptides released from the digestion of pressurised whey can attenuate the inflammatory responses of CF respiratory epithelial cells. Hydrolysates of pressurised WP (pWP) and native WP (nWP, control) were generated in vitro and tested for anti-inflammatory properties judged by the suppression of IL-8 production in CF and non-CF respiratory epithelial cell lines (CFTE29o-and 1HAEo-, respectively). We observed that, in both cell lines, pWP hydrolysate suppressed IL-8 production stimulated by lipopolysaccharide (LPS) to a greater magnitude compared with nWP hydrolysate. Neither hydrolysate suppressed IL-8 production induced by TNF-a or IL-1b, suggesting an effect on the Toll-like receptor (TLR) 4 pathway, the cellular sensor for LPS. Further, neither hydrolysate affected TLR4 expression or neutralised LPS. Both pWP and nWP hydrolysates similarly reduced LPS binding to surface TLR4, while pWP tended to more potently increase extracellular antioxidant capacity. In conclusion: (1) anti-inflammatory properties of whey are enhanced by pressurisation; (2) suppression of IL-8 production may contribute to the clinical effects of pressurised whey supplementation on CF; (3) this effect may be partly explained by a combination of reduced LPS binding to TLR4 and enhanced extracellular antioxidant capacity.

Endotoxin-neutralizing activity and mechanism of action of a cationic α-helical antimicrobial octadecapeptide derived from α-amylase of rice

“…These results suggested that CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) specifically binds to the lipid A moiety of LPS because there was little or no difference in the EC 50 and K D of CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) between LPS and lipid A. However, the EC 50 and K D of AmyI-1-18 for lipid A are approximately 580-and 8600-fold lower than those of CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25), respectively. These results demonstrated that AmyI-1-18 has much higher binding affinity for lipid A than CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)…”

“…The almost negligible differences in both the EC 50 and K D of AmyI-1-18 between LPS and lipid A strongly supported the assertion that AmyI-1-18 specifically binds to the lipid A moiety of LPS through electrostatic and hydrophobic interactions and thereby is capable of detoxifying these endotoxins. In our previous study [45], we reported the ability of CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) to inhibit NO production in RAW264 cells stimulated with LPS or lipid A from E. coli CL(14-25) significantly repressed endotoxin-induced NO production in mouse microphage cells. Further, we examined the interaction between CL(14-25) and LPS or lipid A.…”

“…Further, we examined the interaction between CL(14-25) and LPS or lipid A. In a chromogenic LAL assay, the EC 50 values of CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) were 98 and 122 M for lipid A and LPS, respectively. In SPR analysis, the K D values of CL(14-25) were 4.8 × 10 −6 M and 3.0 × 10 −6 M for lipid A and LPS, respectively.…”

“…We also investigated the inhibitory ability of CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) against the endotoxic activities of LPSs from Escherichia coli and periodontopathic Aggregatibacter actinomycetemcomitans [45]. We found that CL (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) could inhibit both LPS-induced IL-6 production in human aortic endothelial cells and LPS-induced NO production in mouse macrophages (RAW264). Moreover, CL(14-25) exhibited a protective effect against lethal toxicity of LPS in mice.…”

Bioactive dietary peptides and amino acids in inflammatory bowel disease

“…A soyderived tri-peptide was recently identified with anti-inflammatory activity to modulate severity of colitis and suppress secretion of pro-inflammatory cytokines via an intestinal proton-dependent peptide transporter (h-PepT1) (KovacsNolan et al 2012 andYoung et al 2012). Also, dietary peptides derived from whey protein have been identified with anti-inflammatory properties to inhibit IL-8 production from lipopolysaccharide (LPS)-induced respiratory epithelial cells by blocking LPS binding with TLR4 (Iskandar et al 2013). Administration of a dietary Ala-Gln dipeptide was shown to reduce expression of inflammatory mediators and elevate expression of mucin 2 and heat shock protein 72, thereby enhancing the recovery of mucosa in a DSSinduced mouse model (Hou et al 2013).…”