GLP-1 derivatives with functional sequences transit and migrate through trigeminal neurons.

Patients with dementia are increasing with the aging of the population, and dementia has become a disease with high unmet medical needs. Glucagon-like peptide-1 (GLP-1), a neuropeptide, has been reported to improve learning and memory following intracerebroventricular administration. We focused on intranasal administration, which can deliver drugs noninvasively and efficiently to the brain. Although much of the human nasal mucosa is occupied by respiratory epithelium, many capillaries are present in the paracellular route of respiratory epithelium. Therefore, to incorporate GLP-1 into cells, we created a GLP-1 derivative by adding cell-penetrating peptides (CPP) and penetration accelerating sequences (PAS) to GLP-1. We investigated in vitro and in vivo function of PAS-CPP-GLP-1 to enable the translocation of GLP-1 directly from nose to brain. PAS-CPP-GLP-1 enhanced cellular uptake by macropinocytosis with CPP, efficiently escaped from the endosomes due to PAS, and exited the cells. PAS-CPP-GLP-1 also transited trigeminal nerve cells through axon transport and migrated to the adjacent trigeminal nerve cell. Moreover, PAS-CPP-GLP-1 showed significant improvement in learning memory in mice within 20 min of intranasal administration. These results suggested CPP and PAS may be important for the efficient transfer of GLP-1 to the site of action in the brain following intranasal administration.

Involvement of trigeminal axons in nose-to-brain delivery of glucagon-like peptide-2 derivative.

In our previous study, we created a glucagon-like peptide-2 (GLP-2) derivative with the functional sequence PAS-CPP to achieve efficient uptake by the respiratory epithelium and trigeminal nerve. By using octaarginine for cell penetrating peptides (CPP) and FFLIPKG, a reverse sequence of a part of the cathepsin D sequence for the penetration accelerating sequence (PAS), we found that the derivative was taken up by the cells through macropinocytosis and efficiently escaped from the endosomes and exited the cells. Moreover, it showed drug effects by intranasal (in.) administration at the same dose as intracerebroventricular (icv.) administration, which is direct drug administration into the brain. The purpose of this study was to elucidate the cause of the drug effect of in. administered PAS-CPP-GLP-2 at the same dose as that by icv. administration. The present results suggested that although icv. administered PAS-CPP-GLP-2 entered the cerebrospinal fluid, it barely penetrated the perivascular space of the brain, and therefore, only a small amount of the administered dose may have reached the site of action in the brain. In contrast, it was qualitatively suggested that in. administered PAS-CPP-GLP-2 migrates from the trigeminal nerve to the central nervous system via the principal sensory trigeminal nucleus and then through the trigeminal lemniscus. The present results show that nose-to-brain delivery by trigeminal axons, which is assumed to be a transcellular pathway, may be possible. As the drug can be delivered into the nerve, it is expected to be applied not only as a central delivery route but also for the treatment of neurological diseases.

Pulmonary administration of curcumin inhibits B16F10 melanoma lung metastasis and invasion in mice.

PURPOSE: Curcumin is expected to have beneficial effects including an anti-cancer effect. However, its lower bioavailability is a critical concern and limits the utility of curcumin in clinical practice. In this study, we investigated whether transpulmonary delivery of curcumin is pharmacologically effective along with improving its bioavailability in mice with lung metastasis. METHODS: C57BL/6J mice were injected with B16F10 melanoma cells via their tail vein and given curcumin by pulmonary administration every other day. The lung tissue of the vehicle-treated mice on day 17 was covered by nodules of metastatic melanoma. RESULTS: Pulmonary curcumin administration significantly and dose-dependently protected the lung metastasis of melanoma. The phosphorylation of JNK (c-Jun NH2 terminal kinase) and HLJ1 expression levels in the lung metastatic nodules of the melanoma were significantly increased by pulmonary curcumin administration. The anti-metastatic effect of curcumin was blunted in mice injected with HLJ1 knocked-down B16F10 melanoma. Systemic bioavailability after pulmonary administration was 61-times higher than after oral administration. Additionally, the curcumin concentration in the lung tissue was sustained to a high level until 24 h after pulmonary administration. CONCLUSIONS: This study showed the usefulness of curcumin to suppress lung metastasis of melanoma by pulmonary administration, a method that may overcome the low-bioavailability of curcumin.