TRANSCELLULAR DELIVERY OF AN INSULIN-TRANSFERRIN CONJUGATE IN ENTEROCYTE-LIKE CACO-2 CELLS

Authors
Citation
D. Shah et Wc. Shen, TRANSCELLULAR DELIVERY OF AN INSULIN-TRANSFERRIN CONJUGATE IN ENTEROCYTE-LIKE CACO-2 CELLS, Journal of pharmaceutical sciences, 85(12), 1996, pp. 1306-1311
Citations number
25
Categorie Soggetti
Chemistry,"Pharmacology & Pharmacy
ISSN journal
00223549
Volume
85
Issue
12
Year of publication
1996
Pages
1306 - 1311
Database
ISI
SICI code
0022-3549(1996)85:12<1306:TDOAIC>2.0.ZU;2-0
Abstract
Insulin, acylated with dimethylmaleic anhydride, was conjugated to tra nsferrin (Tf) via a disulfide linkage. The molar insulin: Tf ratio in the conjugate was 3:1. The insulin-Tf conjugate (insulin-Tf) was teste d for the transport of insulin across enterocyte-like Caco-2 cell mono layers by the process of transferrin receptor (TfR)-mediated transcyto sis. The uptake of insulin-Tf in Caco-2 cells was TfR-mediated but not insulin receptor-mediated. Transport studies showed that insulin-Tf t ransport was 5- to 15-fold higher than free insulin transport across C aco-2 cells in both apical-to-basal and basal-to-apical directions. Br efeldin A (BFA), an agent that we have previously shown to cause an in crease in TfR transcytosis, further enhanced the transport of the conj ugated insulin three-fold in both directions; thus, a combination of t he conjugate and BFA can cause a net 45-fold increase in the apical-to -basolateral transport of insulin across Caco-2 cell monolayers. The t ransported conjugate was intact as indicated by elution on a Sephadex G-50 column. Insulin in the transcytosed conjugate, unlike the origina l dimethylmaleyl insulin, was capable of binding to anti-insulin antib odies, indicating that free amino groups of insulin were regenerated e ither during or after the transcytotic process. Because Caco-2 cell mo nolayers provide a good model for intestinal epithelium, the insulin-T f conjugate in combination with BFA can be a rational approach to incr ease the oral absorption of insulin in vivo.