Neutralization of IL-17A abrogates protection, and reduces gastric inflammation and proliferation of MLN cells in sublingually immunized IFN-γ^-/- mice.

<p>IFN-γ^<b>-/-</b> mice were sublingually immunized with <i>H</i>. <i>pylori</i> lysate antigens and CT (SL) or left unimmunized (Inf) and infected with live <i>H</i>. <i>pylori</i> bacteria. Mice were injected intraperitoneally neutralizing IL-17A antibody (αIL-17A) or control IgG antibody (IgG). Two weeks post infection mice were sacrificed. <b>A.</b> Stomach tissue was analyzed for <i>H</i>. <i>pylori</i> colonization by quantitative culture and expressed as mean log₁₀ cfu per stomach, and SEM. <b>B.</b> analysis of IL-17A secretion in stomach tissue extracts and <b>C.</b> Atrophy and <b>D.</b> Infiltration in stomach tissue was scored. n = 6–11 mice/group, pool of two experiments. Bars represent mean. Statistically significant difference between sublingually immunized IFN-γ^<b>-/-</b> mice injected neutralizing IL-17A antibody compared to immunized mice injected isotype control antibody was calculated by an unpaired two-tailed t-test with Welch correction and denoted by * (p<0.05), ** (p<0.01), *** (p<0.001). <b>F.</b> single cell suspensions of MLN were prepared and cultured <i>in vitro</i> with <i>H</i>. <i>pylori</i> lysate antigens. Counts per minute (cpm) of incorporated radioactive thymidine was used as a measure of proliferation of the cells. Bars represent mean value and standard deviation (SD) counts in 6 individual wells in pooled mice (n = 5–7 mice/group) <b>G.</b> Supernatants were collected from <i>in vitro</i> cultured MLN (from D) and assessed for IL-17A shown in pg/ml, of six pooled wells. Data pool of two independent experiments. <b>E.</b> Stomach tissue was analyzed for gene expression of Lcn (Lipocalin-2) and expressed as relative gene expression where unimmunized infection control was set to 1. Statistically significant difference between sublingually immunized IFN-γ^<b>-/-</b> mice injected neutralizing IL-17A antibody compared to immunized mice injected isotype control antibody was calculated by an unpaired two-tailed t-test with Welch’s correction and denoted by *** (p<0.001).