Anti-LPS antibodies protect against Klebsiella pneumoniae by empowering neutrophil-mediated clearance without neutralizing TLR4
Taylor S. Cohen, … , Qun Wang, C. Kendall Stover
Taylor S. Cohen, … , Qun Wang, C. Kendall Stover
Published May 4, 2017
Citation Information: JCI Insight. 2017;2(9):e92774. https://doi.org/10.1172/jci.insight.92774.
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Research Article Infectious disease Microbiology

Anti-LPS antibodies protect against Klebsiella pneumoniae by empowering neutrophil-mediated clearance without neutralizing TLR4

Abstract

Initial promising results with immune sera guided early human mAb approaches against Gram-negative sepsis to an LPS neutralization mechanism, but these efforts failed in human clinical trials. Emergence of multidrug resistance has renewed interest in pathogen-specific mAbs. We utilized a pair of antibodies targeting Klebsiella pneumoniae LPS, one that both neutralizes LPS/TLR4 signaling and mediates opsonophagocytic killing (OPK) (54H7) and one that only promotes OPK (KPE33), to better understand the contribution of each mechanism to mAb protection in an acutely lethal pneumonia model. Passive immunization 24 hours prior to infection with KPE33 protected against lethal infection significantly better than 54H7, while delivery of either mAb 1 hour after infection resulted in similar levels of protection. These data suggest that early neutralization of LPS-induced signaling limits protection afforded by these mAbs. LPS neutralization prevented increases in the numbers of γδT cells, a major producer of the antimicrobial cytokine IL-17A, the contribution of which was confirmed using il17a-knockout mice. We conclude that targeting LPS for OPK without LPS signaling neutralization has potential to combat Gram-negative infection by engaging host immune defenses, rather than inhibiting beneficial innate immune pathways.

Authors

Taylor S. Cohen, Mark Pelletier, Lily Cheng, Meghan E. Pennini, Jessica Bonnell, Romana Cvitkovic, Chew-shun Chang, Xiaodong Xiao, Elisabetta Cameroni, Davide Corti, Elena Semenova, Paul Warrener, Bret R. Sellman, JoAnn Suzich, Qun Wang, C. Kendall Stover

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Figure 1

Anti-LPS mAbs protect against K.

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Anti-LPS mAbs protect against K. pneumoniaepneumonia. (A) In vitro neut...
pneumoniaepneumonia. (A) In vitro neutralization of LPS at various concentrations of mAb or polymixin b (PMB) control. (B) Survival of C57BL/6 mice prophylactically immunized with control or anti-LPS mAbs and infected 24 hours later with K. pneumoniae (1 × 104 CFU KP8045) (****P < 0.0001 KPE33 vs. 54H7) (n = 26 per group). (C) Survival of C3H/HeOuJ mice prophylactically immunized 24 hours prior to infection (1 × 104 CFU KP8045) (n = 20, *P = 0.0042). mpk, mg/kg. (D) Survival of C57BL/6 mice treated with control or anti-LPS mAbs 1 hour after infection with K. pneumoniae (1 × 104 CFU KP8045) (n = 10 per group). (E) Survival of C3H/HeJ mice prophylactically immunized with control or anti-LPS mAbs and infected 24 hours later with K. pneumoniae (1 × 104 CFU KP8045) (n = 20 per group). (F) K. pneumoniae CFU recovered from the lungs of C57BL/6 mice prophylactically immunized with control or anti-LPS mAbs 24 hours prior to infection (1 × 104 CFU KP8045) (*P < 0.05 vs. c-IgG). (G) K. pneumoniae CFU recovered from the lungs of C3H/HeOuJ mice at 48 hours after infection. Mice were prophylactically immunized with either control or anti-LPS mAbs 24 hours prior to infection or similar (1 × 104 CFU KP8045) (*P < 0.0001 vs. c-IgG). (H) K. pneumoniae CFU recovered from the lungs of C3H/HeJ mice prophylactically immunized with control or anti-LPS mAbs 24 hours prior to infection (1 × 104 CFU KP8045). Statistical significance was determined by ANOVA followed by Dunn’s test (bacterial CFU) or log-rank test (survival). Data are representative of at least 2 independent experiments (A and F–H) or the compilation of at least 2 independent experiments (B–E). (F–H) Bars represent medians.