Transport Study of Egg-Derived Antihypertensive Peptides (LKP and IQW) Using Caco-2 and HT29 Coculture Monolayers

Abstract

The objective of this study was to investigate the mechanisms of the transport of antihypertensive tripeptides LKP (Leu-Lys-Pro) and IQW (Ile-Gln-Trp) derived from egg white using a coculture system of Caco-2 and HT29 cell monolayers. The results revealed that LKP and IQW have no cytotoxicity to the cell viability after 2 h incubation, could be transported intact across coculture monolayers (apparent permeability coefficient: (18.11 ± 1.57) × 10 and (13.21 ± 1.12) × 10 cm/s, respectively), and were resistant to peptidase secreted by enterocytes. In addition, the transports were significantly inhibited by dipeptide Gly-Pro (P < 0.05), a competitive substance of peptide transporter 1 (PepT1). The transports from apical to basolateral side were significantly higher than that of the reverse direction (P < 0.05). These results suggest that PepT1 is involved in LKP and IQW transports. The transports were also significantly decreased by theaflavin-3'-O-gallate (P < 0.05), an enhancer of tight junction (TJ) and increased by cytochalasin D (P < 0.05), a disruptor of TJ but not influenced by wortamanin, a transcytosis inhibitor, suggesting that passive paracellular route via TJs is also involved in LKP and IQW transports but not transcytosis. In addition, siRNA was also used to knockdown the expression of PepT1 and significantly inhibited the transport (P < 0.05), confirming that PepT1 is involved in transport process. Therefore, both passive paracellular route via TJ and active route via PepT1 coexist in the transport of antihypertensive LKP and IQW across Caco-2/HT29 coculture monolayers.

Current understanding of transport and bioavailability of bioactive peptides derived from dairy proteins: a review

“…The human GIT has many paracellular diffusion pores, also called TJs consisting of zonula occludens‐1, occludin and claudin proteins. Table shows that a variety of DBPs are transported by the energy‐independent paracellular route via TJs (Quirós et al ., ), such as His‐Leu‐Pro‐Leu‐Pro (HLPLP; Quirós et al ., ), Lys‐Val‐Leu‐Pro‐Val‐Pro (KVLPVP; Sun et al ., ), LKP (Gleeson et al ., , ; Xu et al ., ), Arg‐Leu‐Ser‐Phe‐Asn‐Pro (RLSFNP; Guo et al ., ), Arg‐Trp‐Gln (RWQ), Trp‐Gln (WQ; Fernández‐Musoles et al ., ), Ser‐Arg‐Tyr‐Pro‐Ser‐Tyr (SRYPSY), Tyr‐Pro‐Phe‐Pro‐Gly (YPFPG), Tyr‐Pro‐Phe‐Pro‐Gly‐Pro‐Ile (YPFPGPI; Sienkiewicz‐Szłapka et al ., ), Val‐Leu‐Pro‐Val‐Pro (VLPVP; Lei et al ., ) and VPP (Satake et al ., ). However, β‐casein‐f(193–209) cannot be transported via diffusion due to its long length and hydrophobicity (Regazzo et al ., ).…”

“…Peptides are transported via PepT1 coupled with H + . Various DBPs are transported via PepT1 (Table 2), including Ile-Pro-Pro (IPP; Gleeson et al, 2017Gleeson et al, , 2018, Leu-Lys-Pro (LKP; Gleeson et al, 2017Gleeson et al, , 2018Xu et al, 2017), b-Ala-His (Shimizu, 2004) and Tyr-Pro-Ile (Miguel et al, 2008). However, PepT1 cannot transport peptide C (Val-Leu-Pro-Val-Pro-Gln-Lys, VLPVPQK) or BCM-5 (Tyr-Pro-Phe-Pro-Gly, YPFPG; Vij et al, 2016), and its transport capacity is limited to di-and tripeptides only.…”

“…Transport mechanism of DBPs across the intestinal brush-border membrane presented in the lumen are transported across the intestinal brush-border membrane into the bloodstream via one or more of the following routes: (i) peptide transport 1 (PepT1)-mediated route, (ii) paracellular route via tight junctions (TJs), (iii) transcytosis route and (iv) passive transcellular diffusion (Daniel, 2004;Horner et al, 2016;Xu et al, 2017;Matsui, 2018). In the epithelial cells and blood, DBPs are partially hydrolyzed by peptidases into AAs (Fig.…”

Dipeptide (Methionyl-Methionine) Transport and Its Effect on β-Casein Synthesis in Bovine Mammary Epithelial Cells

“…Uptake of small peptides by the cells is mediated by peptide transporters located on the plasma membrane of different epithelial cells [8]. Four peptide transporters, including peptide transporter 1 (PepT1), peptide transporter 2 (PepT2), peptide histidine transporter 1 (PhT1), and peptide histidine transporter 2 (PhT2) have been identified in mammalian cells [8][9][10][11]. PepT2 is predominantly expressed in the kidney and mammary gland [9,10].…”

Preparation, Bioavailability, and Mechanism of Emerging Activities of Ile‐Pro‐Pro and Val‐Pro‐Pro

“…Paracellular route via TJ is also common in the absorption of di-and tripeptides (Fernandez-Musoles et al, 2013). Besides, some peptides are transported by both active and passive routes (Xu, Fan, Yu, Hong, & Wu, 2017).…”