Spray-Dried Formulation of Epicertin, a Recombinant Cholera Toxin B Subunit Variant That Induces Mucosal Healing

Abstract

Epicertin (EPT) is a recombinant variant of the cholera toxin B subunit, modified with a C-terminal KDEL endoplasmic reticulum retention motif. EPT has therapeutic potential for ulcerative colitis treatment. Previously, orally administered EPT demonstrated colon epithelial repair activity in dextran sodium sulfate (DSS)-induced acute and chronic colitis in mice. However, the oral dosing requires cumbersome pretreatment with sodium bicarbonate to conserve the acid-labile drug substance while transit through the stomach, hampering its facile application in chronic disease treatment. Here, we developed a solid oral formulation of EPT that circumvents degradation in gastric acid. EPT was spray-dried and packed into enteric-coated capsules to allow for pH-dependent release in the colon. A GM1-capture KDEL-detection ELISA and size-exclusion HPLC indicated that EPT powder maintains activity and structural stability for up to 9 months. Capsule disintegration tests showed that EPT remained encapsulated at pH 1 but was released over 180 min at pH 6.8, the approximate pH of the proximal colon. An acute DSS colitis study confirmed the therapeutic efficacy of encapsulated EPT in C57BL/6 mice upon oral administration without gastric acid neutralization pretreatment compared to vehicle-treated mice (p < 0.05). These results provide a foundation for an enteric-coated oral formulation of spray-dried EPT.

Characterization and utility of novel monoclonal antibodies to cholera toxin B subunit

“…The pleiotropic functions of CTB have recently been expanded through the construction of CTB variants with novel biological activities, including a plant-made CTB variant modified with C-terminal hexapeptide extension containing a KDEL endoplasmic reticulum (ER) retention motif, 19 later designated as EPICERTIN, 20 which showed a significant enhancement of mucosal wound healing activity in the colon. [21][22][23][24][25] In mice, oral administration of EPICERTIN increased specific subsets of immune cell populations, such as macrophages, natural killer cells, Treg cells and T H 17 cells in the colon lamina propria and upregulated wound healing pathways mediated by TGF-β in the colon.…”

Characterization and utility of novel monoclonal antibodies to cholera toxin B subunit

“…The pleiotropic functions of CTB have recently been expanded through the construction of CTB variants with novel biological activities, including a plant-made CTB variant modi ed with C-terminal hexapeptide extension containing a KDEL endoplasmic reticulum (ER) retention motif, 19 later designated as EPICERTIN, 20 which showed a signi cant enhancement of mucosal wound healing activity in the colon. [21][22][23][24][25] In mice, oral administration of EPICERTIN increased speci c subsets of immune cell populations, such as macrophages, natural killer cells, Treg cells and T H 17 cells in the colon lamina propria and upregulated wound healing pathways mediated by TGF-β in the colon.…”