Fig 2: Anti-CCL20 antibody therapy lowers CSF inflammation in vivo. Although blockage of CCL20 using an anti-CCL20 antibody was not reflected in clinical differences, it resulted (A) in a decrease of CSF pleocytosis 24 h after infection. (B) This was associated with increased brain bacterial titers. (C) Blood bacterial titers were not affected. (*) p<0.05 compared with infected animals that received control antibodies. AB = antibody. N = 10 per group.

Fig 3: The pro-inflammatory effect of the CCL20/CCR6 axis seems independent of IL-17 production.IL17 was up-regulated in the CSF of (A) humans and (B) mice with pneumococcal meningitis. (C) However, antibody blockage of IL-17 in experimental pneumococcal meningitis did not lead to a reduction of inflammation in the CSF. P<0.05 as compared with uninfected controls. Number of animals: n = 5 mice per group.

Fig 4: In patients with acute bacterial meningitis, (A) CCL20 cerebrospinal fluid (CSF) levels were significantly elevated compared with controls.CCL20 CSF levels of patients with pneumococcal meningitis correlated to (B) CSF white blood cell (WBC) counts, (C) CSF blood glucose ratio, and (D) CSF protein levels (see text for details).

Fig 5: CCL20 chemoattracts granulocytes in vitro and in vivo. HoxB8 precursor cells could be differentiated into neutrophils, as indicated by the expression of Gr1. (A, B) The differentiated neutrophils were CCR6 positive. (C, D) Stimulation with TNF-α led to a marked increase of CCR6 expression in differentiated Hoxb8 neutrophils. Whereas (E, F) unstimulated bone marrow-derived neutrophils were CCR6-negative, (G, H) CCR6 became detectable on these cells upon exposure to heat-killed pneumococci (HKP). Using a chemotaxis assay, (I) differentiated Hoxb8 neutrophils and (K) bone marrow derived neutrophils migrated towards CCL20 in a dose-dependent way, demonstrating an in vitro chemotactic effect of CCL20 protein on CCR6 positive granulocytes. FMLP and CXCL2 were used as positive controls. (*) p<0.05 compared with Hoxb8 exposed to medium. (H) After intrathecal injection of recombinant CCL20 (rCCL20, n = 7) in wild type mice, a chemotactic effect was seen in comparison to injection with heat inactivated rCCL20 (rCCL20i, control, n = 7). In addition, rCCL20 co-administration to HKP led to a significant increase of the CSF-pleocytosis compared with rCCL20i co-administration to HKP (n = 8 for each group). (*) p<0.05 compared with rCCL20i or HKP+rCCL20i respectively.