C57BL/6 mice were immunized sublingually with H. pylori lysate antigens and cholera toxin adjuvant or left unimmunized, and then challenged with live H. pylori bacteria. Stomach tissue was taken at 3, 7, 14 and 21 days after challenge and bacterial colonization, chemokine and chemokine receptor gene expression, and influx of cells into the stomach mucosa were evaluated.
RT-PCR array screening revealed differential expression of a broad range of chemokine and chemokine receptor genes between immunized and unimmunized mice. A significant upregulation of chemokines known to attract, among other cells, eosinophils (CCL8), T cells (CXCL10, CXCL11) and neutrophils (CXCL2, CXCL5) and of their cognate receptors CCR3, CXCR3 and CXCR2, preceded or coincided with vaccine-induced protection, which was first evident 7 days after infection and was then sustained at the later time-points. Consistent with the increase in chemokines and chemokine receptors flow cytometric analysis indicated a sequential accumulation of CD4+ T cells, eosinophils, neutrophils and CD103+ dendritic cells in the gastric lamina propria of immunized mice.
This study provides insights into vaccination-induced chemokines that guide the influx of protective immune cells into the stomach of H. pylori infected mice.