Figure 7. Impact of C. jejuni formic acid metabolism and perception on immunopathology in “humanized” mice.

Hfa mice were generated as described (see methods) and orally infected with the C. jejuni wildtype strain (B2 WT), or with isogenic mutants deficient in the formate dehydrogenase subunit D (B2ΔfdhD) or the formic acid receptor (B2Δcj0952c). The average numbers of apoptotic cells (positive for Caspase-3, panel A), neutrophilic granulocytes (neutrophils, positive for MPO-7, panel B), T-lymphocytes (positive for CD3, panel C), regulatory T-cells (Treg, positive for FOXP3, panel D) and B-lymphocytes (positive for B220, panel E) from at least six high power fields (HPF, 400× magnification) per animal were determined microscopically in immunohistochemically stained colon sections of naïve, non-infected (None, open circles) and infected (B2 WT: filled circles; B2ΔfdhD: grey circles; B2Δcj0952c: crossed circles) mice at d12 post infection. Numbers of analyzed animals are given in parentheses. Means (black bars) and levels of significance (P-values) as compared to the respective groups (determined by Student's t-test) are indicated. Data shown are representative for three independent experiments.