Purpose: To observe the anti-caries effect of transgenic tomato anti-caries vaccine after immunization with SD rats by gavage and to explore its immunity mechanism initially.
Methods: SD rats were used to establish an experimental caries model. The transgenic anti-caries tomatoes expressing the target protein were cultivated and identified. The SIgA and IgG contents of specific anti-PAcA in saliva and blood samples of SD rats were detected by ELISA. Then, the SD rats were sacrificed, the maxillary and mandibular bones were taken for Keyes dental caries score, and spleens were taken for the analysis of RNA-seq. Statistical analysis was performed with SPSS 18.0 software package.
Results: The target protein concentration in the transgenic tomato anti-caries vaccine was 36.28 μg/mL. After vaccine immunization of SD rats, group D (8 mL/kg) produced the highest levels of specific SIgA and IgG antibodies at week 6 and was significantly different from the other groups(P＜0.05), and caries counting score was also significantly different than the other groups (P＜0.05). The spleen mRNA of SD rats in group D was extracted and sequenced by RNA-seq, and 40 genes with significant differences in mRNA expression were obtained(P-adjust＜0.05, |Fold Change|≥1.5). 26 genes were significantly upregulated, including IGFBP6 and COL15A1. The upregulated gene GO enrichment was enriched to humoral immune response, B-cell activation, and immunoglobulin receptor binding; KEGG enrichment was enriched to 56 signaling pathways, including PI3K-AKT and NF-κB, and F＜0.001. Fourteen genes were significantly downregulated, but the analysis of downregulated gene GO and KEGG enrichment was not statistically significant(F＞0.1).
Conclusions: Transgenic tomato anti-caries vaccine may reduce caries occurrence by upregulating the activation of PI3K-AKT signaling pathway mediated by IGFBP6 in SD rats.