An intestinal paracellular pathway biased toward positively-charged macromolecules

Khaled Almansour, Alistair Taverner, Jerrold Turner, Ian Eggleston, Randall Mrsny

Research output: Contribution to journalArticlepeer-review

18 Citations (SciVal)


Lacking an effective mechanism to safely and consistently enhance macromolecular uptake across the intestinal epithelium, prospects for successful development of oral therapeutic peptide drugs remain unlikely. We previously addressed this challenge by identifying an endogenous mechanism that controls intestinal paracellular permeability that can be activated by a peptide, termed PIP 640, which can increase cellular levels of phosphorylated myosin light chain at position S 19 (MLC-pS 19). Apical application in vitro or luminal application in vivo was shown to increase macromolecular solute transport within minutes that recovered completely within a few hours after removal. We now examine the nature of PIP 640-mediated permeability changes. Confluent Caco-2 cell monolayers treated with PIP 640 enhanced apical-to-basolateral (AB) transport of 4-kDa, but not 10-kDa, dextran. Expression and/or cellular distribution changes of tight junction (TJ) proteins were restricted to increased claudin-2 over a time course that correlated with an apparent shift in its distribution from the nucleus to the membrane fraction of the cell. PIP 640-mediated epithelial changes were distinct from the combined actions of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). While TNF-α/IFN-γ treatment also increased MLC-pS 19 levels, these cytokines enhanced AB transport for 70-kDa dextran and decreased occludin expression at TJs. Claudin-2-dependent changes induced by PIP 640 resulted in an AB transport bias for positively-charged macromolecules demonstrated in vitro using charge variants of 4-kDa dextrans and by comparing transport of salmon calcitonin to exenatide. Comparable outcomes of increased TJ localization of claudin-2 and enhanced transport of these therapeutic peptides that biased toward cationic characteristics was demonstrated in vivo following after intra-luminal injection into rat jejunum. Together, these data have shown a potential mechanism for PIP 640 to enhance paracellular permeability of solutes in the size range of small therapeutic peptides that is biased toward positively-charged solutes.

Original languageEnglish
Pages (from-to)111-125
Number of pages15
JournalJournal of Controlled Release
Early online date6 Sept 2018
Publication statusPublished - 28 Oct 2018

Bibliographical note

Copyright © 2018 Elsevier B.V. All rights reserved.


  • Cell penetrating peptide
  • Insulin delivery
  • Myosin light chain phosphatase
  • Paracellular transport
  • Protein-protein interactions
  • Tight junction function

ASJC Scopus subject areas

  • Pharmaceutical Science


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