Study on the therapeutic effect of chitosan nanoparticles used as a Bla g 7 polypeptide antigen in sensitized mice.

To investigate the therapeutical effect of the chitosan(CS) nana-paritclessingle administration of Blag 7 polypeptide-CS nanoparticles used as a Bla g 7 polypeptide antigen in the sensitized mice and to explore its immune mechanism,the polypeptide Blag 7 was enclosed into CS to develop the Blag 7 polypeptide entrapped CS nano-particles.In the present experiment,25 BALB/c mice were divided randomly into the Blag 7 polypeptide treated group(group A,n= 5),Blag 7 polypeptide plus CS treated group(group B,n= 5),CS=control group(group C,n= 5),model group(group D,n= 5) and negative control group(group E,n= 5),After sensitization by intraperitoneal route and challenged by intranasal instillation with crude extracts of German cockroach,the inflammatory changes in the mouse lung tissues were observed after the lung tissues were fixed and stained with haematoxylin and eosin(HE).The total cell number and the cellular composition of bronchoalveolar lavage fluid(BALF) were detected;and the changes of the mouse airway hyper-reactivity were determined by the whole body plethysmograohy pre-and post-treatments.In these ways,the Bla g 7 peptide CS nano-particel vaccine was successfully developed.It was found that the pathological changes in mouse lungs in group D were not so prominent in comparison with those of group A of mice sensitized with crude extract of German cockroach.in which the development of eosinophil infiltration in the airway of mice in D group could be demonstrated.The lung inflammatory reactions and the mucus secretion in lungs of D group were significantly alleviated than those of the B group.but there was no therapeutical effect for the mice fed with the isodoses of Blag 7 polypeptide or CS.It was also shown that the airway hyper-reactivity of mice was depressed after treatment(P0.05).It is evident that CS nano-particles show definite therapeutical effect and may serve as a powerful vehicle to improve the tolerance effect of the Blag 7 polypeptide-CS nanoparticle vaccine,and a single administration of Blag 7 polypeptide-CS nanoparticle vaccine may hold promise as a new strategy to desensitize the Blag 7 sensitized disease.