RESUMEN
OBJECTIVES: To investigate whether growing human nasal epithelium as primary cultures alters aminopeptidase B (APB), aminopeptidase N (APN) and dipeptidyldipeptidase (DPPIV) metabolic characteristics, and mRNA gene transcript expression. METHODS: The formation of 7-amino-methyl coumarin from specific substrates for APN (L-alanine-4-methyl-coumaryl-7-amide, APB (L-arginine-4-methyl-coumaryl-7-amide) and DPPIV (glycyl-L-proline-4-methyl-coumaryl-7-amide) was used to estimate the KM, Vmax and the effect of aminopeptidases inhibitors on the enzymes. Polymerase chain reaction was used to investigate gene expression. KEY FINDINGS: Results of this study showed that: (1) both the excised tissues and primary cultures of human nasal epithelium expressed APN, APB and DPPIV activity; (2) the KM of APB, APN and DPPIV was not significantly different in cell and tissue homogenates; (3) except for APN, the Vmax was not significantly different in the two metabolism models; (4) there was no statistically significant difference in the behaviours of APB, APN and DPPIV in response to inhibition by puromycin and bestatin in the two models; (5) the mRNA transcripts that encode APB, APN and DPPIV were expressed in both cell culture and tissue homogenate. CONCLUSIONS: Based on the results of this study, it may be concluded that nasal primary culture system is suitable for investigating peptide and protein metabolism and enzymatic stability in human nasal epithelium. Except for APN, the tissue culture conditions did not significantly alter the functional and molecular expression of the aminopeptidases.
Asunto(s)
Aminopeptidasas/metabolismo , Antígenos CD13/metabolismo , Dipeptidil Peptidasa 4/metabolismo , Mucosa Nasal/enzimología , Aminopeptidasas/antagonistas & inhibidores , Aminopeptidasas/genética , Antígenos CD13/antagonistas & inhibidores , Antígenos CD13/genética , Células Cultivadas , Cumarinas/metabolismo , Dipeptidil Peptidasa 4/genética , Células Epiteliales/enzimología , Humanos , Técnicas In Vitro , Cinética , Leucina/análogos & derivados , Leucina/farmacología , Mucosa Nasal/citología , Reacción en Cadena de la Polimerasa , Inhibidores de Proteasas/farmacología , Inhibidores de la Síntesis de la Proteína/farmacología , Puromicina/farmacologíaRESUMEN
Nasal drug delivery has now been recognized as a very promising route for delivery of therapeutic compounds including biopharmaceuticals. It has been demonstrated that low absorption of drugs can be countered by using absorption enhancers or increasing the drug residence time in the nasal cavity, and that some mucoadhesive polymers can serve both functions. This article reviews the background of nasal mucoadhesive drug delivery with special references to the biological and pharmaceutical considerations for nasal mucoadhesive drug administration. Applications of nasal mucoadhesives for the delivery of small organic molecules, antibiotics, proteins, vaccines and DNA are also discussed. Furthermore, new classes of functionalized mucoadhesive polymers, the characterization and safety aspects of nasal drug products as well as the opportunities presented by nasal drug delivery are extensively discussed.
Asunto(s)
Administración Intranasal , Sistemas de Liberación de Medicamentos , Mucosa Nasal , Adhesividad , Animales , Fenómenos Biofísicos , Biofisica , Sistemas de Liberación de Medicamentos/efectos adversos , Humanos , Adhesivos TisularesRESUMEN
The objective of this study was to investigate absorption enhancing approaches for systemic delivery of methionine enkephalin via the nose. Absorption promotion of methionine enkephalin in the presence of protease inhibitors (bestatin, puromycin) and absorption enhancers (glycocholate, dimethyl-beta-cyclodextrin) were investigated in human nasal epithelium. Co-administration of the peptide with protease inhibitors and absorption enhancers resulted in a remarkable increase in Met-Enk permeation (4- to 94-fold). The increase was proportional to transepithelial resistance reduction and permeation of paracellular marker dye. Perturbation of the epithelial tight junctions seen in vitro may not occur in vivo due to mucus protection and mucociliary clearance.
Asunto(s)
Encefalina Metionina/farmacocinética , Leucina/análogos & derivados , Mucosa Nasal/metabolismo , Transporte Biológico/efectos de los fármacos , Células Cultivadas , Cilios , Dextrinas/farmacología , Encefalina Metionina/farmacología , Ácido Glicocólico/farmacología , Humanos , Leucina/farmacología , Mucosa Nasal/citología , Inhibidores de Proteasas/farmacología , Puromicina/farmacologíaRESUMEN
PURPOSE: The purpose of this study was to provide functional and molecular evidence to support the existence of large neutral amino acid transporters in human nasal epithelium using nasal primary cell culture model. METHODS: L-Phenylalanine was used as a model substrate to characterize carrier-mediated permeation of amino acids across human nasal epithelium. The influence of temperature, concentration, other amino acids, metabolic/transport inhibitors, and polarity/stereo-selectivity on transport of the model compound was investigated. Reverse transcriptase polymerase chain reaction was used for molecular characterization of the existence of the transporters. RESULTS: The transport of L-phenylalanine across the human nasal epithelium was polarized (apical --> basolateral >> basolateral --> apical), saturable (Km = 1.23 mM; Vmax = 805.1 nmol/mg protein/min) and stereo-selective (permeation of L-phenylalanine >> D-Phenylalanine). Its permeation was significantly (< 0.05) reduced by cationic, small and large neutral amino acids, oubain, amiloride, sodium-free medium, and temperature lowering. Reverse transcriptase polymerase chain reaction revealed the presence of the broad-scope cationic-dependent amino acid transporter gene (y+LAT-2) in the human nasal epithelium. CONCLUSIONS: Based on the results of this study, one may postulate that the human nasal epithelium expresses L-amino acid transporters. More studies are necessary for detailed characterization of the transporters.
Asunto(s)
Sistemas de Transporte de Aminoácidos/metabolismo , Mucosa Nasal/metabolismo , Fenilalanina/metabolismo , Sistemas de Transporte de Aminoácidos/genética , Animales , Transporte Biológico Activo , Células Cultivadas , Humanos , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , TemperaturaRESUMEN
The aim of this study was to investigate the suitability of a sequential monolayer-suspension culture system as a model to screen subacute effects of drug excipients on ciliary beat frequency (CBF). The CBF of the cultured cells was measured by computerized microscope photometry. Protease inhibitors (puromycin, bestatin, bacitracin, actinonin and thiomersal) were used as model compounds and the mechanisms of ciliary inhibition were investigated by probing the involvement of arachidonic acid metabolism, guanylate cyclase (cGMP), protein kinase C (PKC) and adenosinetriphosphate (ATP) inhibition. Bestatin concentration-dependently reduced CBF by inhibiting arachidonic acid metabolism, cGMP, PKC and endogenous ATP consumption. Thiomersal and DMSO used for dissolving actinonin reduced CBF (P<0.05) via a non-specific mechanism. Bacitracin (8 mM) and puromycin (135 mM) had no effect on CBF after acute exposure (15-30 min) (P>0.05), but significantly reduced the CBF by approximately 15.0% following daily 15-min exposure for 1 week. This study shows that (i) sequential monolayer-suspension culture system is a valid model to screen both acute and subacute effects of drug excipients on CBF; and (ii) bacitracin, puromycin and actinonin are more cilio-compatible than bestatin and thiomersal and as such are more potentially useful nasal absorption enhancer from ciliotoxicity perspective.
Asunto(s)
Mucosa Nasal/citología , Mucosa Nasal/efectos de los fármacos , Inhibidores de Proteasas/farmacología , Técnicas de Cultivo de Célula/métodos , Células Cultivadas , Cilios/efectos de los fármacos , Cilios/enzimología , Cilios/fisiología , Humanos , Mecánica , Mucosa Nasal/enzimología , Mucosa Nasal/fisiologíaRESUMEN
This study examined the potential usefulness of cultured human nasal epithelium as a model to investigate nasal absorption enhancement strategies for therapeutic peptides. The transport of leucine enkephalin (Leu-Enk) in the presence of bestatin and puromycin, respectively and various combinations of these protease inhibitors with absorption enhancers capable of inhibiting proteases or protecting peptides against protease degradation (glycocholate, dimethyl-beta-cyclodextrin (DM beta CD)) was studied. Epithelial membrane perturbation, protein leakage, bestatin/puromycin absorption and rebound aminopeptidase activity were used as toxicological end-points. The combination of puromycin with glycocholate or DM beta CD resulted in a higher absorption enhancement of Leu-Enk (9-14%) than when the absorption enhancers were combined with bestatin (1-3%) or when the inhibitors were used alone (2-4%). The higher absorption enhancement resulting from the combination of protease inhibitors with absorption enhancers caused a significant reduction of epithelial resistance and increased sodium fluorescein transport. Although only puromycin permeated the human nasal epithelium, both protease inhibitors induced a significant rebound aminopeptidase activity (25-61%), which can be associated with protein leakage (21-46%). This study highlighted (i) the potential usefulness of cultured human nasal epithelium as a model to study nasal absorption enhancement of therapeutic peptides; (ii) further studies using in vivo nasal models are required to ascertain whether the membrane perturbation and cytotoxicity observed with various combinations of the protease inhibitors and absorption enhancers really raise safety concerns.