Th immune response induced by H pylori vaccine with chitosan as adjuvant and its relation to immune protection

摘要

AIM:To study the immunological protective effect of H pylori vaccine with chitosan as an adjuvant and its mechanism.METHODS:Female BALB/c mice were randomly divided into seven groups and orally immunized respectively with PBS,chitosan solution,chitosan particles,H pylori antigen,H pylori antigen plus cholera toxin(CT),H pylori antigen plus chitosan solution,H pylori antigen plus chitosan particles once a week for four weeks.Four weeks after the last immunization,the mice were challenged twice by alive H pylori(1 × 109 CFU/mL)and sacrificed.Part of the gastric mucosa was embedded in paraffin,cut into sections and assayed with Giemsa staining.Part of the gastric mucosa was used to quantitatively culture H pylori.ELISA was used to detect cytokine level in gastric mucosa and anti-H pylori IgG1,IgG2a levels in serum.RESULTS:In the groups with chitosan as an adjuvant,immunological protection was achieved in 60% mice,which was significantly higher than in groups with H pylori antigen alone and without H pylori antigen(P < 0.05 or 0.001).Before challenge,the level of IFN and IL-12 in gastric mucosa was significantly higher in the groups with chitosan as an adjuvant than in the control group and the group without adjuvant(P < 0.05 or 0.005).After challenge,the level of IFN and IL-12 was significantly higher in the groups with adjuvant than in the groups without adjuvant and antigen(P < 0.05 or 0.001).Before challenge,the level of IL-2 in gastric mucosa was not different among different groups.Afterchallenge the level of IL-2 was significantly higher in the groups with adjuvant than in the control group(P < 0.05 or 0.001).Before challenge,the level of IL-10 in gastric mucosa was significantly higher in the groups with chitosan as an adjuvant than in other groups without adjuvant(P < 0.05 or 0.01).After challenge,the level of IL-10 was not different among different groups.Before challenge,the level of IL-4 in gastric mucosa was significantly higher in the groups with chitosan as an adjuvant than in other groups without adjuvant(P < 0.05).After challenge,the level of IL-4 was significantly higher in the groups with chitosan particles as an adjuvant than in the group with CT as an adjuvant(P < 0.05),and in the group with chitosan solution as an adjuvant,the level of IL-4 was significantly higher than that in control group,non-adjuvant group and the groups with CT(P < 0.05 or 0.001).The ratio of anti-H pylori IgG2a/IgG1 in serum was significantly lower in the groups with chitosan as an adjuvant than in the groups with CT as an adjuvant or without adjuvant(P < 0.01).CONCLUSION:H pylori vaccine with chitosan as an adjuvant can protect against H pylori infection and induce both Th1 and Th2 type immune response.