Structural diversity of Burkholderia pseudomallei lipopolysaccharides affects innate immune signaling

PLoS Negl Trop Dis. 2017 Apr 28;11(4):e0005571. doi: 10.1371/journal.pntd.0005571. eCollection 2017 Apr.

Abstract

Burkholderia pseudomallei (Bp) causes the disease melioidosis. The main cause of mortality in this disease is septic shock triggered by the host responding to lipopolysaccharide (LPS) components of the Gram-negative outer membrane. Bp LPS is thought to be a weak inducer of the host immune system. LPS from several strains of Bp were purified and their ability to induce the inflammatory mediators TNF-α and iNOS in murine macrophages at low concentrations was investigated. Innate and adaptive immunity qPCR arrays were used to profile expression patterns of 84 gene targets in response to the different LPS types. Additional qPCR validation confirmed large differences in macrophage response. LPS from a high-virulence serotype B strain 576a and a virulent rough central nervous system tropic strain MSHR435 greatly induced the innate immune response indicating that the immunopathogenesis of these strains is different than in infections with strains similar to the prototype strain 1026b. The accumulation of autophagic vesicles was also increased in macrophages challenged with highly immunogenic Bp LPS. Gene induction and concomitant cytokine secretion profiles of human PBMCs in response to the various LPS were also investigated. MALDI-TOF/TOF was used to probe the lipid A portions of the LPS, indicating substantial structural differences that likely play a role in host response to LPS. These findings add to the evolving knowledge of host-response to bacterial LPS, which can be used to better understand septic shock in melioidosis patients and in the rational design of vaccines.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Burkholderia pseudomallei / chemistry*
  • Burkholderia pseudomallei / immunology*
  • Cell Line
  • Gene Expression Profiling
  • Immunity, Innate*
  • Immunologic Factors / genetics
  • Lipopolysaccharides / chemistry*
  • Lipopolysaccharides / immunology*
  • Lipopolysaccharides / isolation & purification
  • Macrophages / immunology*
  • Macrophages / microbiology
  • Mice, Inbred BALB C
  • Nitric Oxide Synthase Type II / analysis
  • Real-Time Polymerase Chain Reaction
  • Signal Transduction*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Tumor Necrosis Factor-alpha / analysis

Substances

  • Immunologic Factors
  • Lipopolysaccharides
  • Tumor Necrosis Factor-alpha
  • Nitric Oxide Synthase Type II

Grants and funding

This work was supported in part by the US Department of Homeland Security grant no. HSHQDC-10-C-00135 and by the UF Emerging Pathogens Institute to AT, and the UF Emerging Pathogens Institute Seed grant 16-3 to MHN. HPS was supported by Preeminence Program start up funds from the University of Florida. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.