TLR4-dependent early recruitment of phagocytes to airways is critical for Bordetella pertussis clearance

MORENO, GRISELDA ; AGUSTINA ERREA; ROY ROBERTS; AUGUSTO GRAIEB; MAELE, LAURYE VAN ; SIRARD, JEAN CLAUDE ; BENEKE, ARNDT ; RUMBO M,; DANIELA HOZBOR.

Bs As

Congreso; Pimer congreso Franco- Argentino de Inmunología; 2010

Though it is well known that TLR4 dependent processes contribute to adaptative anti-pertussis immunity, there is scarce knowledge on antimicrobial scenario during the early stage of B. pertussis infection. The aim of this study was to characterize the cell populations recovered from broncoalveolar lavage at 2, 6, and 24 h after B. pertussis mice intranasal infection (1.108CFU/40μl). By flow cytometry we observed that the influx of neutrophils (PMN, CD11c-, CD11b+, Ly6G+) into the airways was significant in TLR4 competent mice, rising from less than 1.103/BALF to 7.105 ± 1.105 cells/BALF at 6h. For TLR4 deficient mice strain (C3H/HeJ mice strain), recruitment of PMN was evident only at 24h, being in all time points analyzed lower than in TLR4 competent strain. Thus, the expression of proinflammatory chemokines such as CXCL1, CXCL2, CXCL5 was higher in TLR4 competent mice in comparison with those observed in C3H/HeJ mice. Depletion of PMN by specific monoclonal antibodies, increased bacterial loads from 7.7±0.12 to 8.4±0.53 logCFU/lung at 24 hs (p=0.097) and 7.15 ± 0.21 to 8.36 ± 0.026 log CFU/lung at 48h (p=0.002). Using CFSE labeled bacteria we observed that during the first 24h of infection bacteria were mainly associated to PMN (27,66±0,66 vs 11,41±1,99% at 6h and 16,54±3,02 vs 7,29±6,33% at 24h. This result seems to be independent of TLR4 since there was no difference between TLR4 competent and deficient mice strains. As an effector mechanism we observed that PMN contained higher level of reactive oxygen species (ROS) in comparison with AM cell population PMN ROS+: 33.72±1.50% vs AM ROS+: 9.10±3.89% at 6hs; 57.70±10.18 vs 18.50±5.10% at 24h), indicated that PMN were the main producer of ROS in the first 24hs of infection. Alltogether the results presented here indicate that TLR4 activation at early time points of B. pertussis infection is critical for eliciting anti-pertussis response and PMNs recruitment participates actively in this elimination activity.