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Kim YH, Kim KJ, D’Argenio DZ, Crandall ED. Characteristics of Passive Solute Transport across Primary Rat Alveolar Epithelial Cell Monolayers. MEMBRANES 2021; 11:331. [PMID: 33946241 PMCID: PMC8145727 DOI: 10.3390/membranes11050331] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 11/16/2022]
Abstract
Primary rat alveolar epithelial cell monolayers (RAECM) were grown without (type I cell-like phenotype, RAECM-I) or with (type II cell-like phenotype, RAECM-II) keratinocyte growth factor to assess passive transport of 11 hydrophilic solutes. We estimated apparent permeability (Papp) in the absence/presence of calcium chelator EGTA to determine the effects of perturbing tight junctions on "equivalent" pores. Papp across RAECM-I and -II in the absence of EGTA are similar and decrease as solute size increases. We modeled Papp of the hydrophilic solutes across RAECM-I/-II as taking place via heterogeneous populations of equivalent pores comprised of small (0.41/0.32 nm radius) and large (9.88/11.56 nm radius) pores, respectively. Total equivalent pore area is dominated by small equivalent pores (99.92-99.97%). The number of small and large equivalent pores in RAECM-I was 8.55 and 1.29 times greater, respectively, than those in RAECM-II. With EGTA, the large pore radius in RAECM-I/-II increased by 1.58/4.34 times and the small equivalent pore radius increased by 1.84/1.90 times, respectively. These results indicate that passive diffusion of hydrophilic solutes across an alveolar epithelium occurs via small and large equivalent pores, reflecting interactions of transmembrane proteins expressed in intercellular tight junctions of alveolar epithelial cells.
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Affiliation(s)
- Yong Ho Kim
- Will Rogers Institute Pulmonary Research Center and Hastings Center for Pulmonary Research, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0906, USA; (Y.H.K.); (K.-J.K.)
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0906, USA
| | - Kwang-Jin Kim
- Will Rogers Institute Pulmonary Research Center and Hastings Center for Pulmonary Research, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0906, USA; (Y.H.K.); (K.-J.K.)
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0906, USA
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089-1111, USA;
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9037, USA
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089-9121, USA
| | - David Z. D’Argenio
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089-1111, USA;
| | - Edward D. Crandall
- Will Rogers Institute Pulmonary Research Center and Hastings Center for Pulmonary Research, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0906, USA; (Y.H.K.); (K.-J.K.)
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0906, USA
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-9092, USA
- Mork Family Department of Chemical Engineering and Materials Science, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089-1211, USA
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Angelo R, Rousseau K, Grant M, Leone-Bay A, Richardson P. Technosphere insulin: defining the role of Technosphere particles at the cellular level. J Diabetes Sci Technol 2009; 3:545-54. [PMID: 20144294 PMCID: PMC2769873 DOI: 10.1177/193229680900300320] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Technosphere Insulin (TI) is a novel inhalation powder for the treatment of diabetes mellitus. Technosphere Insulin delivers insulin with an ultra rapid pharmacokinetic profile that is distinctly different from all other insulin products but similar to natural insulin release. Such rapid absorption is often associated with penetration enhancers that disrupt cellular integrity. METHODS Technosphere Insulin was compared to a panel of known penetration enhancers in vitro using the Calu-3 lung cell line to investigate the effects of TI on insulin transport. RESULTS Measures of tight junction integrity such as transepithelial electrical resistance, Lucifer yellow permeability, and F-actin staining patterns were all unaffected by TI. Cell viability and plasma membrane integrity were also not affected by TI. In contrast, cells treated with comparable (or lower) concentrations of penetration enhancers showed elevated Lucifer yellow permeability, disruption of the F-actin network, reduced cell viability, and compromised plasma membranes. CONCLUSIONS These results demonstrate that TI is not cytotoxic in an in vitro human lung cell model and does not function as a penetration enhancer. Furthermore, TI does not appear to affect the transport of insulin across cellular barriers.
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Characterization of protein factor(s) in rat bronchoalveolar lavage fluid that enhance insulin transport via transcytosis across primary rat alveolar epithelial cell monolayers. Eur J Pharm Biopharm 2008; 69:808-16. [PMID: 18406118 DOI: 10.1016/j.ejpb.2008.01.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Revised: 01/22/2008] [Accepted: 01/25/2008] [Indexed: 11/20/2022]
Abstract
The aim of this study was to characterize factor(s) in rat bronchoalveolar lavage fluid (BALF) that enhance(s) insulin transport across primary rat alveolar epithelial cell monolayers (RAECM) in primary culture. BALF was concentrated 7.5-fold using the Centricon device and the retentate was used to characterize the factor(s) involved in enhancing apical-to-basolateral transport of intact 125I-insulin across various epithelial cell monolayers. These factor(s) enhanced transport of intact insulin across type II cell-like RAECM (3-fold increase) and type I cell-like RAECM (2-fold increase), but not across Caco-2 or MDCK cell monolayers. The insulin transport-enhancing factor(s) were temperature- and trypsin-sensitive. The mechanism of enhancement did not seem to involve paracellular transport or fluid-phase endocytosis, since fluxes of sodium fluorescein and FITC-dextran (70 kDa) were not affected by the factor(s) in the apical bathing fluid. BALF enhancement of intact 125I-insulin transport was abolished at 4 degrees C and in the presence of monensin, suggesting involvement of transcellular pathways. Sephacryl S-200 purification of BALF retentate, followed by LC-MS/MS, indicated that the high molecular weight (>100 kDa) fractions (which show some homology to alpha-1-inhibitor III, murinoglobulin gamma 2, and pregnancy-zone protein) appear to facilitate transcellular transport of insulin across RAECM.
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