Cell-penetrating albumin enhances the sublingual delivery of antigens through macropinocytosis.

Innovations in oral immunotherapy have greatly advanced the therapeutic control of allergies. However, these therapeutic effects suffer from the fact that the amount of antigen delivered to antigen-presenting cells is limited given the formulations that are currently available. We recently designed a cell-penetrating albumin and found that this modified albumin enters cells via the induction of macropinocytosis. Herein, we report on a novel system for delivering antigens based on cell-penetrating albumin-inducible macropinocytosis that allows larger amounts of antigens to be delivered to antigen-presenting cells. A treatment with cell-penetrating albumin significantly increased the permeability of ovalbumin (45 kDa) or dextran (2000 kDa) on monolayers derived from human oral squamous carcinoma cells. Flow cytometric analyses showed that the cell-penetrating albumin treatment resulted in a significant elevation in the amount of dextran that was delivered to two types of antigen-presenting cells. Finally, mice that had been sensitized by Japanese cedar pollen extract (JCPE) and cell-penetrating albumin showed a decline in the frequency of nose-rubbing against a subsequent intranasal administration of JCPE. These findings suggest that the sublingual administration of cell-penetrating albumin efficiently delivers antigens to antigen-presenting cells via the induction of macropinocytosis, resulting in an enhancement in the therapeutic effect of sublingual immunotherapy.

Involvement of the Parathyroid Hormone-Related Protein on Changes in the CYP3A Expression in Cancer Cachexia.

Parathyroid hormone-related protein (PTHrP), which is secreted from a tumor, contributes to the progression of cachexia, a condition that is observed in half of all cancer patients. Although drug clearance was reported to decrease in patients with cancer cachexia, the details have not been clarified. The present study reports on an investigation of whether PTHrP is involved in the alternation of drug metabolism in cases of cancer cachexia. Cancer cachexia model rats with elevated serum PTHrP levels showed a significant decrease in hepatic and intestinal CYP3A2 protein expression. When midazolam, a CYP3A substrate drug, was administered intravenously or orally to the cancer cachexia rats, its area under the curve (AUC) was increased by about 2 and 5 times, as compared to the control group. Accordingly, the bioavailability of midazolam was increased by about 3 times, thus enhancing its pharmacological effect. In vitro experiments using HepG2 cells and Caco-2 cells showed that the addition of serum from cancer cachexia rats or active PTHrP (1-34) to each cell resulted in a significant decrease in the expression of CYP3A4 mRNA. Treatment with a cell-permeable cAMP analog also resulted in a decreased CYP3A4 expression. Pretreatment with protein kinase A (PKA), protein kinase C (PKC), and nuclear factor-kappa B (NF-κB) inhibitors recovered the decrease in CYP3A4 expression that was induced by PTHrP (1-34). These results suggest that PTHrP suppresses CYP3A expression via the cAMP/PKA/PKC/NF-κB pathway. Therefore, it is likely that PTHrP would be involved in the changes in drug metabolism observed in cancer cachexia.

Development of a long acting FGF21 analogue-albumin fusion protein and its anti-diabetic effects.

Fibroblast growth factor 21 (FGF21) is a hormone-like protein that improves blood glucose and lipid metabolism. However, its short half-life and instability are bottlenecks to its clinical applications. In this study, to extend its pharmacological action, we created a stabilized mutant FGF21 (mFGF21:ΔHPIP, P171G, A180E, L118C-A134C, S167A) and then genetically fused it with human albumin (HSA-mFGF21) via a polypeptide linker. Physicochemical analyses suggested that HSA-mFGF21 was formed from both intact HSA and mFGF21. Pharmacokinetic findings indicated the half-life of HSA-mFGF21 was 20 times longer than that of FGF21. In addition, HSA-mFGF21 was persistently distributed in adipose tissue as a target tissue. The in vivo hypoglycemic activity of HSA-mFGF21 using streptozotocin (STZ)-induced type I diabetes model mice, in which insulin secretion was suppressed, showed that a single intravenous administration of HSA-mFGF21 rapidly alleviated hyperglycemia. At that time, HSA-mFGF21 increased GLUT1 mRNA expression in adipose tissue without having any effect on insulin secretion. A twice weekly administration of HSA-mFGF21 continuously suppressed blood glucose levels and ameliorated the abnormalities of adipose tissue induced by STZ treatment. Interestingly, HSA-mFGF21 showed no hypoglycemic effects in healthy mice. Together, HSA-mFGF21 could be a novel biotherapeutic for the treatment of metabolic disorders including diabetes mellitus.