ABSORPTION MECHANISMS FOR PEPTIDE/PROTEIN DRUGS VIA LUNG

生物技术的进步导致新的肽/蛋白质药物对人类健康有很大的希望。不幸的是，口服给药通常是无效的，这些药物必须通过肠外注射。最近，经肺给药作为全身给药的替代途径显示出相当大的潜力。因此，在这项建议中，我们的长期目标是阐明肽和蛋白质药物通过肺泡上皮吸收的机制，肺泡上皮是药物从肺间隙吸收的表面。尽管在动物实验中已经证明蛋白质/多肽药物的肺递送具有良好的生物利用度，但其吸收机制和途径实际上是未知的。与肺给药相关的生物工程问题包括配方模式、给药途径和经上皮转运。其中，我们选择描述肽/蛋白药物在肺泡上皮吸收中可能普遍存在的特定机制。我们将以原代培养的大鼠肺泡上皮细胞单层为体外模型，以二/三肽、粒细胞集落刺激因子和人生长激素为模型药物。我们建议i)描述模型蛋白药物通过肺泡上皮屏障吸收的机制和途径（即细胞旁扩散、液相胞吞作用、受体介导和/或吸附胞吞作用），ii)研究通过肺泡上皮屏障胞吞作用刺激蛋白药物吸收的机制，iii)研究肽药物如何通过肺泡上皮吸收。iv)测定理化变量对蛋白/肽类药物肺泡上皮吸收的刺激作用。通过四个不同的生物医学研究实验室利用跨越细胞生物学到生物（化学）工程的实验方法对肺蛋白/肽药物吸收的合作研究，这些项目的结果将为推进肺药物递送的生物工程方法提供新的信息，包括开发通过肺泡上皮屏障提高生物利用度的新方法。

Biotechnological advances are leading to new peptide/protein drugs of great promise for human health. Unfortunately, oral administration usually is ineffective in delivering such drugs, which must be taken parenterally. Recently, transpulmonary drug delivery has shown considerable potential as an alternative route of systemic delivery. Therefore, in this proposal, our long term goals are to elucidate the mechanisms for absorption of peptide and protein drugs across the alveolar epithelium, the surface across which drug absorption from lung airspaces must occur. Although pulmonary delivery of protein/peptide drugs has been shown in animal studies to lead to promising bioavailabilities, absorption mechanisms and pathways are virtually unknown. Bioengineering related issues pertaining to pulmonary drug delivery include formulation modalities, delivery approaches and transepithelial transport. Of these, we chose to delineate specific mechanisms that may prevail in absorption of peptide / protein drugs across alveolar epithelium. We will utilize primary cultured rat alveolar epithelial cell monolayers as an in vitro model and use di-/tri-peptides, granulocyte-colony stimulating factor and human growth hormone as model drugs. We propose to i) delineate the mechanisms and pathways (i.e., paracellular diffusion, fluid-phase transcytosis, receptor-mediated and/or adsorptive transcytosis) for absorption of model protein drugs across the alveolar epithelial barrier, ii) investigate the mechanisms underlying stimulation of protein drug absorption via transcytosis across the alveolar epithelial barrier, iii) investigate how peptide drugs are absorbed across the alveolar epithelium, and iv) determine the stimulatory effect of physicochemical variables on alveolar epithelial absorption of protein/peptide drugs. Through the collaborative investigation of pulmonary protein/peptide drug absorption among four different biomedical research laboratories utilizing experimental approaches spanning cell biology to bio(chemical)engineering, results from these projects will provide new information for advancing bioengineering approaches to pulmonary drug delivery, including development of new methodologies to improve bioavailability via the alveolar epithelial barrier.