Fig. 4.

Cytokine and chemokine transcription in peripheral blood with experimental A. phagocytophilum infection compared to mock-infected controls differs modestly between untreated and dexamethasone-treated horses. A. phagocytophilum infection in untreated horses (gray bars) induced a proinflammatory response with reduced IL-4 and IL-10 transcription and abundant IL-12 and modest IFNG transcription. Dexamethasone treatment during infection (black bars) dampened or delayed IL-12B and IL-18 transcription and abrogated the suppressed IL-4 transcription, resulting in altered ratios of IL-10 to IFNG and IL-10 to IL-12B throughout most of the infection. Significant differences (repeated-measure ANOVA; P < 0.05) in transcription between untreated and dexamethasone-treated horses are denoted by P values. The lines between panels delineate groups of proinflammatory or anti-inflammatory cytokine or chemokine gene transcriptional responses or ratios of selected responses. The light-gray zones delineate the 2-fold up- and downregulation limits compared to those of mock-infected controls.