AIM

To study the cellular immunity induced by H.pylori vaccine with chitosan as adjuvant and the mechanism of immunological protection.

METHODS

BALB/c mice were randomly divided into nine groups and immunized by (1)PBS alone, (2)chitosan solution alone, (3)chitosan particles alone, (4)H.pylori antigen alone, (5)H.pylori antigen plus chitosan solution, (6)H.pylori antigen plus chitosan particles, (7)H.pylori antigen plus cholera toxin (CT), (8)H.pylori antigen plus chitosan solution and CT, (9)H.pylori antigen plus chitosan particles and CT orally respectively once a week for four weeks. At 4 weeks after the last immunization, mice were challenged by alive H.pylori (1x10(9) CFU/mL) twice at two days intervals. Before and after the challenge, mice were killed in batches and the H.pylori-infection in gastric mucosa was detected by H.pylori culture and Giemsa stain. ELISA and HE stain were used to detect IL-2, IL-4, IL-10 levels and pathologic change in gastric mucosa.

RESULTS

(1)In the groups with chitosan as an adjuvant, 60% mice could achieve immunological protection, which was consistent with using CT as an adjuvant (58.33%), and was more than that when using H.pylori antigen alone or without H.pylori antigen. (2)After challenge, the IL-2 levels in gastric mucosa in the groups with adjuvants were significantly higher than those in the control group (P<0.001-0.05). Moreover, IL-2 levels in the groups with adjuvants after challenge were significantly higher than those before challenge (P<0.05). Before challenge, the IL-10 and IL-4 levels in gastric mucosa were significantly higher in the groups with chitosan as adjuvant than those in non-adjuvant groups (P<0.05). After challenge, IL-10 levels were significantly higher in the groups with chitosan particles as adjuvant than those in other groups (P<0.05); IL-4 levels were significantly higher in the groups with chitosan particles as an adjuvant than those in the group with CT as an adjuvant, and those in the group with chitosan solution as an adjuvant were significantly higher than those in control group, non-adjuvant group and the groups with CT (P<0.05). IL-10 and IL-4 in the groups with adjuvants after challenge were significantly lower than those before challenge (P<0.05). (3)The degree of inflammation in gastric mucosa was significantly lower in the groups with chitosan and chitosan particles as adjuvant than those with CT as adjuvant(P<0.05).

CONCLUSION

(1)H.pylori vaccine with chitosan as an adjuvant has the immune protective effect against H.pylori infection. (2)H.pylori vaccine with chitosan as an adjuvant could reverse the inhibition of Th2 induced by H.pylori infection and recover the Th1/Th2 imbalance, which might contribute to the immune protection against H.pylori. (3)The rate of gastritis induced by H.pylori vaccine with chitosan as adjuvant was significantly lower than those with CT as adjuvant.