GM1-Binding Conjugates To Improve Intestinal Permeability

Abstract

Drugs and proteins with poor intestinal permeability have a limited oral bioavailability. To remediate this problem, a receptor-mediated endocytosis and transcytosis approach was explored. Indeed, the non-toxic β subunit of cholera toxin (CTB) can cross the intestinal barrier by binding to receptor GM1. In this study, we explored the use of GM1-binding peptides and CTB as potential covalent carriers of poorly permeable molecules. GM1-binding peptides (G23, P3) and CTB were conjugated to poorly permeable fluorescent probes such as FITC and albumin-FITC using triethylene glycol spacers and click chemistry.The affinity of the peptide conjugates with receptor GM1 was confirmed by isothermal titration calorimetry or microscale thermophoresis and the results suggested the involvement of non-specific interactions. Conjugating the model drugs to G23 and P3 improved the internalization into Caco-2 and T84 cells, although the process was not dependent of the amount of GM1 receptor. However, conjugation of BSA-FITC to CTB increased the internalization in the same cells in a GM1-dependent pathway.Peptides conjugates demonstrated a limited permeability through a Caco-2 monolayer, whereas G23-and CTB-conjugates slightly enhanced permeability through a T84 cell monolayer compared to model drugs alone. Since CTB can improve the permeability of large macromolecules such as albumin, it is an interesting carrier for the improvement of oral bioavailability of various other macromolecules such as heparins, proteins and siRNAs.

Liver‐Target and Glucose‐Responsive Polymersomes toward Mimicking Endogenous Insulin Secretion with Improved Hepatic Glucose Utilization

“…As shown in Figure S16 in the Supporting Information, the fluorescence intensity of Caco‐2 with GM1 incubation was almost the same as that of the epithelium. It is reported that GM1 was expressed in the intestinal epithelium cells; thus, we can reasonably speculate that in vivo absorption pathways can be estimated from in vitro cellular results 22…”

Retrograde Axonal Transport of Liposomes from Peripheral Tissue to Spinal Cord and DRGs by Optimized Phospholipid and CTB Modification

“…Several mechanisms may underlie this improvement. CTB efficiently enters axons via GM1 receptors [ 69 , 70 ], and CTB-modified liposomes enter cultured cells via the same mechanism as CTB alone [ 29 , 30 ]. Thus, the uptake of liposomes at axons seems to be improved by CTB modification.…”

Detection of Rare Objects by Flow Cytometry: Imaging, Cell Sorting, and Deep Learning Approaches

“…Recently, Chaganti et al described the modified protein FITC labeling technique employing tandem affinity purification tags at the N-and C-termini of the target protein [70]. Currently, FITC is widely used for labeling various entities of biological nature, such as peptides [71,72], antibodies [73,74] and, polysaccharides [75]. Thus, the strategy of cell labeling is based on the fact that specific cell populations express defined surface markers that are unambiguously identified by the corresponding antibodies conjugated with a fluorescent label.…”