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J Mol Biol. 2018 Aug 17;430(17):2641-2660. doi: 10.1016/j.jmb.2018.06.032. Epub 2018 Jun 24.

Mass Spectrometry-based Structural Analysis and Systems Immunoproteomics Strategies for Deciphering the Host Response to Endotoxin.

Author information

1
Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA; University of Maryland School of Medicine, Baltimore, MD 21201, USA.
2
Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA.
3
Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.
4
Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA. Electronic address: dgoodlett@rx.umaryland.edu.
5
Laboratory of Immune System Biology (LISB), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD 20814, USA. Electronic address: nitalazarau@niaid.nih.gov.

Abstract

One cause of sepsis is systemic maladaptive immune response of the host to bacteria and specifically, to Gram-negative bacterial outer-membrane glycolipid lipopolysaccharide (LPS). On the host myeloid cell surface, proinflammatory LPS activates the innate immune system via Toll-like receptor-4/myeloid differentiation factor-2 complex. Intracellularly, LPS is also sensed by the noncanonical inflammasome through caspase-11 in mice and 4/5 in humans. The minimal functional determinant for innate immune activation is the membrane anchor of LPS called lipid A. Even subtle modifications to the lipid A scaffold can enable, diminish, or abolish immune activation. Bacteria are known to modify their LPS structure during environmental stress and infection of hosts to alter cellular immune phenotypes. In this review, we describe how mass spectrometry-based structural analysis of endotoxin helped uncover major determinations of molecular pathogenesis. Through characterization of LPS modifications, we now better understand resistance to antibiotics and cationic antimicrobial peptides, as well as how the environment impacts overall endotoxin structure. In addition, mass spectrometry-based systems immunoproteomics approaches can assist in elucidating the immune response against LPS. Many regulatory proteins have been characterized through proteomics and global/targeted analysis of protein modifications, enabling the discovery and characterization of novel endotoxin-mediated protein translational modifications.

KEYWORDS:

LPS; Proteomics; TLR4; caspase-4/5/11; innate and adaptive immunity

PMID:
29949751
DOI:
10.1016/j.jmb.2018.06.032

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