title: Effect of different intestinal conditions on the intermolecular interaction between insulin and cell-penetrating peptide penetratin and on its contribution to stimulation of permeation through intestinal epithelium.
abstract: Our recent studies have shown that the coadministration of cell-penetrating peptides (CPPs) is a potential strategy for oral delivery of peptide- and protein-based biopharmaceuticals. The intermolecular interaction between drug and CPP is an essential factor in the effective delivery of these drugs, but the characteristics of the interaction under the conditions of the intestinal lumen remain unknown. In this study, therefore, we examined the characteristics of binding of the amphipathic CPP penetratin to insulin and the efficiency of its enhancement of epithelial insulin transport at different pH and in simulated intestinal fluids (SIFs). The binding between insulin and penetratin was pH dependent and particularly decreased at pH 5.0. In addition, we clarified that the sodium taurocholate (NaTC) present in two types of SIF (fasted-state SIF [FaSSIF] and fed-state SIF [FeSSIF]) affected binding efficiency. However, the permeation of insulin through a Caco-2 cell monolayer was significantly facilitated by coincubation with l- or d-penetratin at various pH values. Moreover, the permeation-stimulating effect of l-penetratin was observed in FaSSIF containing NaTC and lecithin, but not in 3mM NaTC solution, suggesting that the presence of lecithin was the key factor in maintaining the ability of penetratin to enhance the intestinal absorption of biopharmaceuticals. This report describes the essential considerations for in vivo use and clinical application of a CPP-based oral delivery strategy.
authors.affiliation: Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe, Hyogo 650-8586, Japan.
authors.forename: Noriyasu
authors.initials: N
authors.lastname: Kamei
authors.affiliation: Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe, Hyogo 650-8586, Japan.
authors.forename: Yukina
authors.initials: Y
authors.lastname: Aoyama
authors.affiliation: Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe, Hyogo 650-8586, Japan; Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Suez Canal University, Ismailia 415-22, Egypt.
authors.forename: El-Sayed
authors.initials: el-S
authors.lastname: Khafagy
authors.affiliation: Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe, Hyogo 650-8586, Japan.
authors.forename: Mao
authors.initials: M
authors.lastname: Henmi
authors.affiliation: Laboratory of Drug Delivery Systems, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe, Hyogo 650-8586, Japan. Electronic address: mmtakeda@pharm.kobegakuin.ac.jp.
authors.forename: Mariko
authors.initials: M
authors.lastname: Takeda-Morishita
mesh_terms: D000284:Administration, Oral; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D057846:Cell-Penetrating Peptides; D002626:Chemistry, Pharmaceutical; D004337:Drug Carriers; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D007328:Insulin / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007700:Kinetics; D054709:Lecithins / Q000737:chemistry; D008954:Models, Biological; D010539:Permeability; D011485:Protein Binding; D013656:Taurocholic Acid / Q000737:chemistry; D013678:Technology, Pharmaceutical / Q000379:methods; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D004337:Drug Carriers; D007004:Hypoglycemic Agents; D007328:Insulin; D054709:Lecithins; D013656:Taurocholic Acid; C414409:penetratin
keywords: Caco-2 cells; Cell-penetrating peptide; Insulin; Intermolecular interaction; Oral absorption; Penetratin