A Novel In Vitro Membrane Permeability Methodology Using Three-dimensional Caco-2 Tubules in a Microphysiological System Which Better Mimics In Vivo Physiological Conditions.

The aim of this study was to develop an in vitro drug permeability methodology which mimics the gastrointestinal environment more accurately than conventional 2D methodologies through a three-dimensional (3D) Caco-2 tubules using a microphysiological system. Such a system offers significant advantages, including accelerated cellular polarization and more accurate mimicry of the in vivo environment. This methodology was confirmed by measuring the permeability of propranolol as a model compound, and subsequently applied to those of solifenacin and bile acids for a comprehensive understanding of permeability for the drug product in the human gastrointestinal tract. To protect the Caco-2 tubules from bile acid toxicity, a mucus layer was applied on the surface of Caco-2 tubules and it enables to use simulated intestinal fluid. The assessment using propranolol reproduced results equivalent to those obtained from conventional methodology, while that using solifenacin indicated fluctuations in the permeability of solifenacin due to various factors, including interaction with bile acids. We therefore suggest that this model will serve as an alternative testing system for measuring drug absorption in an environment closely resembling that of the human gastrointestinal tract.

The mechanism of solifenacin release from a pH-responsive ion-complex oral suspension in the fasted upper gastrointestinal lumen.

The main objective of this study was to investigate the mechanism of solifenacin release from a pH-responsive ion-complex oral resinate suspension under conditions simulating the environment in the upper gastrointestinal lumen. A secondary objective was to propose an appropriate in vitro methodology for evaluating the quality of orally administered solifenacin suspensions. The mechanism of solifenacin release from polacrilin potassium resin (Amberlite® IRP88) was investigated using biorelevant media and compendial setups (USP Apparatus 2 and USP Apparatus 4) and using newer, recently validated in vitro methodologies [biorelevant gastrointestinal transfer (BioGIT) system]. We evaluated the impact of particle size and concentration of the resin; thickener concentration (carbomer homopolymer, type B); and the impact of pH, cationic strength, agitation intensity and level of simulation of contents in the upper gastrointestinal lumen. Data suggested that solifenacin release from the resinate was determined by the resin particle size, the medium pH, cationic strength (when the conditions in the upper small intestine are simulated) and the level of simulation of contents in the upper small intestine. The interaction of solifenacin with taurocholic acid/lecithin aggregates was significant, but unlikely to affect the degree of solifenacin absorption, as a BCS Class I compound. Under acidic conditions, solifenacin was dissociated and released from the pH-responsive resin rapidly. Under conditions simulating the contents of the upper small intestine, solifenacin was replaced by cations from the testing media and diffused through the resin matrix. All three in vitro systems with or without a pH gradient are useful in distinguishing solifenacin release characteristics from resinate suspensions with different particle sizes. Because of this drug release mechanism, USP Apparatus 2 with fixed pH media demonstrated equivalent or slightly higher discriminative sensitivity than the other setups and appears to be appropriate for product quality control.

Effect of 4-[(5,6,7,8-Tetrahydro-5,5,8,8-Tetramethyl-2-Naphthalenyl)Carbamoyl]Benzoic Acid (Am80) on Alveolar Regeneration in Adiponectin Deficient-Mice Showing a Chronic Obstructive Pulmonary Disease-Like Pathophysiology.

Chronic obstructive pulmonary disease (COPD) is an intractable pulmonary disease that causes widespread and irreversible alveolar collapse. Although COPD occurs worldwide, only symptomatic therapy is currently available. Our objective is the development of therapeutic agents to eradicate COPD. Therefore, we focused on 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl) carbamoyl] benzoic acid (Am80), which is a derivative of all-trans retinoic acid. We evaluated the effects of Am80 on alveolar repair in a novel COPD model of adiponectin-deficient mice. This mouse model has more symptoms similar to human COPD than the classic elastase-induced emphysema mouse model. Lung volume, computed tomography (CT) values, low-attenuation area ratios, and bone and fat mass were measured by CT. However, the administration of Am80 did not affect these results. To examine the degree of destruction in the alveoli, the mean linear intercept of the alveolar walls was calculated, and assessment of this value confirmed that there was a significant difference between the control (46.3 ± 2.3 µm) and 0.5 mg/kg Am80-treated group (34.4 ± 1.7 µm). All mice survived the treatment, which lasted for more than 6 months, and we did not observe any abnormalities in autopsies performed at 80 weeks of age. These results suggested that Am80 was effective as a novel therapeutic compound for the treatment of COPD.

Pulmonary administration of 1,25-dihydroxyvitamin D3 to the lungs induces alveolar regeneration in a mouse model of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disease with several causes, including smoking, and no curative therapeutic agent is available, particularly for destructive alveolar lesions. In this study, we investigated the differentiation-inducing effect on undifferentiated lung cells (Calu-6) and the alveolar regenerative effect of the active vitamin 1,25-dihydroxy vitamin D3 (VD3) with the ultimate goal of developing a novel curative drug for COPD. First, the differentiation-inducing effect of VD3 on Calu-6 cells was evaluated. Treatment with VD3 increased the proportions of type I alveolar epithelial (AT-I) and type II alveolar epithelial (AT-II) cells constituting alveoli in a concentration- and treatment time-dependent manner, demonstrating the potent differentiation-inducing activity of VD3 on Calu-6 cells. We thus administered VD3 topically to the mice lung using a previously developed intrapulmonary administration via self-inhalation method. To evaluate the alveolus-repairing effect of VD3, we administered VD3 intrapulmonarily to elastase-induced COPD model mice and computed the mean distance between the alveolar walls as an index of the extent of alveolar injury. Results showed significant decreases in the alveolar wall distance in groups of mice that received 0.01, 0.1, and 1µg/kg of intrapulmonary VD3, revealing excellent alveolus-regenerating effect of VD3. Furthermore, we evaluated the effect of VD3 on improving respiratory function using a respiratory function analyzer. Lung elasticity and respiratory competence [forced expiratory volume (FEV) 1 s %] are reduced in COPD, reflecting advanced emphysematous changes. In elastase-induced COPD model mice, although lung elasticity and respiratory competence were reduced, VD3 administered intrapulmonarily twice weekly for 2weeks recovered tissue elastance and forced expiratory volume in 0.05s to the forced vital capacity, which are indicators of lung elasticity and respiratory competence, respectively, to levels comparable to those in normal mice. These results revealed the potent activity of VD3 in inducing differentiation of the Calu-6 cells and the effect of topical administration of VD3 to the lungs to induce lung regeneration at histological and functional levels, demonstrating the potential of VD3 as a curative agent for alveolar destruction in COPD.

[Fusion vaccine therapy by IL-2-gene-transduced dendritic cells and tumor cells].

We evaluated the usefulness of fusion vaccine prepared from IL-2-gene-transduced splenic dendritic cells (DCs) and fibrosarcoma tumor cells (QRsP) in treating of lung metastasis. The IL-2 or LacZ gene was transferred into spleen-derived DCs using an adenoviral vector. Irradiated QRsP tumor cells were fused with IL-2 gene transduced DCs (fusion/IL-2) or LacZ gene transduced DCs (fusion/LacZ) by polyethyleneglycol. These fusion cells expressed major histocompatibility complex (MHC) class I and MHC class II, CD86, CD11c and CD8alpha. IFN-gamma and cytotoxic T lymphocyte (CTL) activity of splenic lymphocytes in mice vaccinated with fusion cells increased significantly as compared with those of DC or tumor cells vaccinated mice. CTL levels in fusion/IL-2-vaccinated mice were higher than that in fusion/LacZ-vaccinated mice. The number of lung metastasis in the fusion/IL-2 or fusion/LacZ-vaccineatd mice was significantly lower than that in mice vaccinated with DCs, tumor or PBS. The introduction of the IL-2 gene into fusion cells produced more potent therapeutic effects. Our results suggest that the fusion cells prepared from IL-2 gene transduced spleen derived DCs and tumor cells have the ability to induce therapeutic effect against lung metastasis.

[Reduction of immunosuppression and shift to Th1 response by tumor-DC (dendritic cells) fusion vaccine].

Immunotherapy with tumor-dendritic cells (DC) fusion vaccine has been shown to induce an immune response against multiple tumor antigens including unknown tumor antigens. In this study, we examined immunological changes by tumor-DC fusion vaccine. Nine patients with advanced or recurrent gastrointestinal cancer that was unresponsive to standard surgical therapy and chemotherapy were enrolled in this study after informed consent was obtained. Monocytes were separated from the peripheral blood collected by leukapheresis, and were cultured with GM-CSF and IL-4 for 6 days. Then, TNF-alpha, IL-1beta, IL-6 and PGE2 were added for maturation of DC. Fusion of irradiated tumor cells and DC was created by polyethylene glycol and electroporation. The fusion vaccine was injected subcutaneously into the inguinal region four times every two weeks. There were no adverse effects or autoimmune responses after vaccination in any patients. The clinical response was stable in five patients, and disease progression in four patients. Delayed skin tests changed to positive in six of the nine patients after vaccination. IAP levels decreased in five patients and TGF-beta levels decreased in six patients. Th1/Th2 and Tc1/Tc2 balances improved in six of the nine patients after vaccination. In this study, it was shown that immunosuppressive factors, such as IAP and TGF-beta, and Th1 balance are useful as markers of immunomonitoring for tumor-DC fusion vaccine in patients with advanced or recurrent gastrointestinal patients.