Efficacy of Albendazole-Chitosan Microsphere-based Treatment for Alveolar Echinococcosis in Mice

Abstract

This study aimed to investigate the pharmacology and anti-parasitic efficacy of albendazole-chitosan microspheres (ABZ-CS-MPs) for established intraperitoneal infections of Echinococcus multilocularis metacestodes in an experimental murine model. Male outbred Kunming mice infected with E. multilocularis Metacestodes were administered with three ABZ formulations, namely, ABZ-CS-MPs, Liposome-Albendazole (L-ABZ), and albendazole tablet (ABZ-T). Each of the ABZ formulations was given orally at three different doses of 37.5, 75, and 150 mg/kg, three times a week for 12 weeks postinfection. After administering the drugs, we monitored the pharmacological performance and anti-parasitic efficacy of ABZ-CS-MPs compared with L-ABZ, and ABZ-T treated mice. ABZ-CS-MPs reduced the weight of tissues containing E. multilocularis metacestodes most effectively compared with the ABZ-T group and untreated controls. Metacestode grown was Highly suppressed during treatment with ABZ-CS-MPs. Significantly higher plasma levels of ABZ metabolites were measured in mice treated with ABZ-CS-MPs or L-ABZ compared with ABZ-T. In particular, enhanced ABZ-sulfoxide concentration profiles were observed in the mice given 150 mg/kg of ABZ-CS-MPs, but not in the mice treated with L-ABZ. Histological examination showed that damages caused disorganization of both the germinal and laminated layers of liver hyatid cysts, demolishing their characteristic structures after treatment with ABZ-CS-MPs or L-ABZ. Over time, ABZ-CS-MPs treatment induced a shift from Th2-dominant to Th1-dominant immune response. CS-MPs As a new carrier exhibited improved absorption and increased bioavailability of ABZ in the treatment of E. multilocularis infections in mice.

Fig 1. Albendazole chitosan microspheres (ABZ-CS-MPs).

ABZ-CS was successfully entrapped by MPs (black arrows) (A: 40×, bar = 500 μm), (B: 100×, bar = 200 μm), (C: 200×, bar = 100 μm), (D: 400×, bar = 50 μm).

Fig 2. Hepatic lesions of mice infected with Echinococcus multilocularis.

(A) ABZ-CS-MPs treated group: Note the highly suppressed vesicular development and yellow discoloration. Metacestodes were obviously calcified. (B) L-ABZ treated group: Note the degeneration of the metacestode biomass on the liver and cloudy white discoloration. (C) ABZ-T treated group: Note the large metacestode biomass. (D) Infection control group: Note the striped translucent vesicles and large metacestode mass almost occupying the entire liver. All infected livers shown were chosen from the 75 mg/kg subgroups.

Fig 3. Histological sections of ABZ-treated and untreated metacestode tissue.

(A) ABZ-CS-MP treatment: Note the high number of germinal layer cells dissolved and the partial dissolution of the laminated layer. (B) L-ABZ treatment: Note the thin, swollen structure of the laminated layer. (C) ABZ-T treatment: Note the irregularly thin laminated layer and the partially detached germinal layer cells. (D) Untreated infection control tissue: Note the intact, regular structure of the laminated and germinal layers. GL: germinal layer; LL: laminated layer; IC: inflammatory cell; FT: fibrous tissue; CT: calcified tissue; (200×).

Fig 4. Transmission electron microscopy (TEM) analysis of drug efficacy in mice infected with E. multilocularis metacestodes and treated with ABZ-CS-MPs, L-ABZ, or ABZ-T.

(A) Untreated infection control: Microtriches (white arrows) appeared intact and were densely arranged with clear structure of laminated layer (LL). A large number of microtriches protrude well into the laminated layer. Cortical cell (Cor) was present (black arrow). (B) and (C) ABZ-CS-MPs and L-ABZ treatment: Note the complete absence of microtriches at the tegumental-laminated layer interface (white arrows). Metacestode tissue appeared severely damaged, with regression of the germinal layer. Structural integrity of the germinal layer was destroyed. Laminated layer sheets were lacking, with vacuolization (vac) of the tissue in germinal layer. (D) ABZ-T treatment: Tegument of laminated layer lessened. A: (5000×, bar = 5 μm); B: (8000×, bar = 2 μm); C: (8000×, bar = 2 μm); D: (8000×, bar = 2 μm).