Fig. 1

Ac2-26 ameliorates meningeal granulocyte infiltration and bacterial load during pneumococcal meningitis. Wildtype (WT) mice were infected by application of 10⁴ colony-forming units (CFU) of Streptococcus pneumoniae D39 type 2 strain into the subarachnoid space with or without Ac2-26 i.p. injection 2, 8, and 24 h after infection. a Ac2-26 reduces neutrophil infiltration into the choroid plexus of the third ventricle (left site) and the frontal interhemispheric region (right site), demonstrated by naphthol AS-D chloroacetate esterase (NCAE) reaction. The figures show representative results from one of five to seven mice per group. b Quantification of neutrophil granulocyte infiltration using neutrophil score (see “Methods” section for detail; t test; **p < 0.01). c Coronal brain sections stained with antibodies against neutrophil granulocytes 28 h after infection with Streptococcus pneumoniae with or without Ac2-26 i.p. injection 2, 8, and 24 h after infection (scale bar = 100 μm). d Densitometric quantification of neutrophil staining was assessed from five mice per experimental group (t test; *p < 0.05). e Quantification of the bacterial load in the blood, spleen, and cerebellum of infected WT mice with or without Ac2-26 treatment (n ≥ 10 each group; Mann-Whitney U test; **p = 0.004 for WT vs. WT + Ac2-26)