Assessment of transport rates of proteins and peptides across primary human alveolar epithelial cell monolayers.
In this study, we investigated bi-directional fluxes (i.e., in absorptive and secretive directions) of human serum proteins [albumin (HSA), transferrin (TF), and immunoglobulin G (IgG)] and peptides/proteins of potential therapeutic relevance [insulin (INS), glucagon-like peptide-1 (GLP-1), growth hormone (GH), and parathyroid hormone (PTH)] across tight monolayers of human alveolar epithelial cells (hAEpC) in primary culture. Apparent permeability coefficients (P(app); x10(-7)cm/s, mean+/-S.D.) for GLP-1 (6.13+/-0.87 (absorptive) versus 1.91+/-0.51 (secretive)), HSA (2.45+/-1.02 versus 0.21+/-0.31), TF (0.88+/-0.15 versus 0.30+/-0.03), and IgG (0.36+/-0.22 versus 0.15+/-0.16) were all strongly direction-dependent, i.e., net absorptive, while PTH (2.20+/-0.30 versus 1.80+/-0.77), GH (8.33+/-1.24 versus 9.02+/-3.43), and INS (0.77+/-0.15 versus 0.72+/-0.36) showed no directionality. Trichloroacetic acid precipitation analysis of tested molecules collected from donor and receiver fluids exhibited very little degradation. This is the first study on permeability data for a range of peptides and proteins across an in vitro model of the human alveolar epithelial barrier. These data indicate that there is no apparent size-dependent transport conforming to passive restricted diffusion for the tested substances across human alveolar barrier, in part confirming net absorptive transcytosis. The obtained data differ significantly from previously published reports utilising monolayers from different species. It can be concluded that the use of homologous tissue should be preferred to avoid species differences.
Saarland University, Biopharmaceutics and Pharmaceutical Technology, 66123 Saarbrücken, Germany.
Michael
M
Bur
Hanno
H
Huwer
Claus-Michael
CM
Lehr
Nina
N
Hagen
Mette
M
Guldbrandt
Kwang-Jin
KJ
Kim
Carsten
C
Ehrhardt
D001798:Blood Proteins / Q000378:metabolism*; D018929:Cell Culture Techniques; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D004058:Diffusion; D004847:Epithelial Cells / Q000378:metabolism*; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism; D006728:Hormones / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D010281:Parathyroid Hormone / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D012709:Serum Albumin / Q000378:metabolism; D013045:Species Specificity; D013997:Time Factors; D014168:Transferrin / Q000378:metabolism
D001798:Blood Proteins; D006728:Hormones; D007074:Immunoglobulin G; D007328:Insulin; D010281:Parathyroid Hormone; D012709:Serum Albumin; D014168:Transferrin; D052216:Glucagon-Like Peptide 1; D013006:Growth Hormone