Influence of Dendritic Cell LKB1 Signaling on Mucosal Adjuvant Effect of FimH

doi:10.13701/j.cnki.kqyxyj.2024.05.004

Abstract

Abstract: Objective: To investigate the impact of liver kinase B1 (LKB1) expression in dendritic cells (DCs) in oral mucosa on the response to mucosal vaccine adjuvants. Methods: CD11^ccre-GFP;LKB1^fl/fl mice (conditional knockout, cKO) were used and littermate LKB1^fl/fl mice were set as wild-type (WT). Firstly, 6-8-week-old cKO and WT mice (n=12 each) were selected, and flow cytometry was used to isolate DCs from mouse oral mucosa for transcriptome high-throughput sequencing. Secondly, using cKO and WT mice (n=16 each), a mouse mucosal immune model was established. Immunizations were performed with ovalbumin (OVA) via submucosal injection in the cheek after 0, 2, and 4 weeks, with or without FimH protein from S.typhimurium (FimH-ST). Serum and saliva were collected at week 3 post-immunization to detect OVA-specific IgG1 and IgG2b in serum and OVA-specific IgA in saliva by enzyme-linked immunosorbent assay (ELISA). At week 6 post-immunization, flow cytometry was performed to detect the number and proportion of immune cells in mouse cheek mucosa and draining lymph nodes (dLN), including submandibular, cervical, and neck lymph nodes. Results: The up-regulated genes of oral mucosal dendritic cells in cKO mice were enriched in innate immune responses and B cell mediated immunity in the Gene Ontology (GO) database. The Toll-like receptor signaling pathway and mTOR signaling pathway were enriched in Gene Set Enrichment Analysis (GSEA). Compared to the WT-OVA group, the WT-OVA+FimH-ST group showed increased levels of serum OVA-specific IgG1 and IgG2b and saliva OVA-specific IgA antibodies; and the numbers and proportions of mucosal local immune B cells and plasma cells were increased. The cKO-OVA group showed higher levels of serum IgG1 and IgG2b and saliva IgA antibodies compared to the WT-OVA group, along with increased proportions of follicular helper T cells (Tfh) and B cells in dLN (P<0.05). However, there was no difference in antibody secretion levels between the cKO-OVA+FimH-ST group and the cKO-OVA group, only showing an increase in Tfh and B cells in dLN. Conclusion: LKB1 regulates innate immune responses and B cell function through DCs; FimH-ST exhibits adjuvant effects when injected submucosally in the mouse oral mucosa; the activation of oral mucosal immune responses by DCs depends on LKB1, and defective LKB1 on DCs leads to the loss of the adjuvant effect of FimH-ST.

Key words: FimH, oral mucosal immune, dendritic cells, liver kimase B1, oral mucosal vaccine

LIU Xinyuan, LIN Yuhong, CHEN Junlan, HUANG Bingbing, LI Yuhong. Influence of Dendritic Cell LKB1 Signaling on Mucosal Adjuvant Effect of FimH[J]. Journal of Oral Science Research, 2024, 40(5): 393-400.

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