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Protective properties of milk sphingomyelin against dysfunctional lipid metabolism, gut dysbiosis, and inflammation. J Nutr Biochem 2019; 73:108224. [DOI: 10.1016/j.jnutbio.2019.108224] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/25/2019] [Accepted: 07/31/2019] [Indexed: 12/20/2022]
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2
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Wu Z, Zhang Z, Lei Z, Lei P. CD14: Biology and role in the pathogenesis of disease. Cytokine Growth Factor Rev 2019; 48:24-31. [PMID: 31296363 DOI: 10.1016/j.cytogfr.2019.06.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 06/21/2019] [Indexed: 12/22/2022]
Abstract
Human monocyte differentiation antigen CD14 is a pattern recognition receptor (PRR) that enhances innate immune responses. CD14 was first identified as a marker of monocytes to signal intracellular responses upon bacterial encounters. Given the absence of an intracellular tail, CD14 was doubted to have the signaling capacities. Later CD14 was confirmed as the TLR co-receptor for the detection of pathogen-associated molecular patterns. However, CD14 has been revealed as a multi-talented receptor. In last decade, CD14 was identified to activate NFAT to regulate the life cycle of myeloid cells in a TLR4-independent manner and to transport inflammatory lipids to induce phagocyte hyperactivation. And its influences on multiple related diseases have been further considered. In this review, we summarize advancements in the basic biology of the CD14 including its structure, binding ligands, signaling pathways, and its roles in the pathogenesis of inflammation, atherosclerosis, tumor and metabolic diseases. We also discuss the therapeutic potential of targeting the CD14 in related diseases.
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Affiliation(s)
- Zhenghao Wu
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Department of Breast and Thyroid Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Zhenxiong Zhang
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Zehua Lei
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Department of Orthopaedic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ping Lei
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Lee JTY, Wang G, Tam YT, Tam C. Membrane-Active Epithelial Keratin 6A Fragments (KAMPs) Are Unique Human Antimicrobial Peptides with a Non-αβ Structure. Front Microbiol 2016; 7:1799. [PMID: 27891122 PMCID: PMC5105358 DOI: 10.3389/fmicb.2016.01799] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 10/26/2016] [Indexed: 11/23/2022] Open
Abstract
Antibiotic resistance is a pressing global health problem that threatens millions of lives each year. Natural antimicrobial peptides and their synthetic derivatives, including peptoids and peptidomimetics, are promising candidates as novel antibiotics. Recently, the C-terminal glycine-rich fragments of human epithelial keratin 6A were found to have bactericidal and cytoprotective activities. Here, we used an improved 2-dimensional NMR method coupled with a new protocol for structural refinement by low temperature simulated annealing to characterize the solution structure of these kerain-derived antimicrobial peptides (KAMPs). Two specific KAMPs in complex with membrane mimicking sodium dodecyl sulfate (SDS) micelles displayed amphipathic conformations with only local bends and turns, and a central 10-residue glycine-rich hydrophobic strip that is central to bactericidal activity. To our knowledge, this is the first report of non-αβ structure for human antimicrobial peptides. Direct observation of Staphylococcus aureus and Pseudomonas aeruginosa by scanning and transmission electron microscopy showed that KAMPs deformed bacterial cell envelopes and induced pore formation. Notably, in competitive binding experiments, KAMPs demonstrated binding affinities to LPS and LTA that did not correlate with their bactericidal activities, suggesting peptide-LPS and peptide-LTA interactions are less important in their mechanisms of action. Moreover, immunoprecipitation of KAMPs-bacterial factor complexes indicated that membrane surface lipoprotein SlyB and intracellular machineries NQR sodium pump and ribosomes are potential molecular targets for the peptides. Results of this study improve our understanding of the bactericidal function of epithelial cytokeratin fragments, and highlight an unexplored class of human antimicrobial peptides, which may serve as non-αβ peptide scaffolds for the design of novel peptide-based antibiotics.
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Affiliation(s)
- Judy T Y Lee
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA
| | - Guangshun Wang
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center Omaha, NE, USA
| | - Yu Tong Tam
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison Madison, WI, USA
| | - Connie Tam
- Department of Ophthalmic Research, Cole Eye Institute and Lerner Research Institute, Cleveland ClinicCleveland, OH, USA; Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve UniversityCleveland, OH, USA
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Kell DB, Pretorius E. On the translocation of bacteria and their lipopolysaccharides between blood and peripheral locations in chronic, inflammatory diseases: the central roles of LPS and LPS-induced cell death. Integr Biol (Camb) 2016; 7:1339-77. [PMID: 26345428 DOI: 10.1039/c5ib00158g] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have recently highlighted (and added to) the considerable evidence that blood can contain dormant bacteria. By definition, such bacteria may be resuscitated (and thus proliferate). This may occur under conditions that lead to or exacerbate chronic, inflammatory diseases that are normally considered to lack a microbial component. Bacterial cell wall components, such as the endotoxin lipopolysaccharide (LPS) of Gram-negative strains, are well known as potent inflammatory agents, but should normally be cleared. Thus, their continuing production and replenishment from dormant bacterial reservoirs provides an easy explanation for the continuing, low-grade inflammation (and inflammatory cytokine production) that is characteristic of many such diseases. Although experimental conditions and determinants have varied considerably between investigators, we summarise the evidence that in a great many circumstances LPS can play a central role in all of these processes, including in particular cell death processes that permit translocation between the gut, blood and other tissues. Such localised cell death processes might also contribute strongly to the specific diseases of interest. The bacterial requirement for free iron explains the strong co-existence in these diseases of iron dysregulation, LPS production, and inflammation. Overall this analysis provides an integrative picture, with significant predictive power, that is able to link these processes via the centrality of a dormant blood microbiome that can resuscitate and shed cell wall components.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry and The Manchester Institute of Biotechnology, The University of Manchester, 131, Princess St, Manchester M1 7DN, Lancs, UK.
| | - Etheresia Pretorius
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Arcadia 0007, South Africa.
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Nagel M, Brauckmann S, Moegle-Hofacker F, Effenberger-Neidnicht K, Hartmann M, de Groot H, Mayer C. Impact of bacterial endotoxin on the structure of DMPC membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2271-6. [DOI: 10.1016/j.bbamem.2015.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/03/2015] [Accepted: 06/07/2015] [Indexed: 12/22/2022]
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Ruysschaert JM, Lonez C. Role of lipid microdomains in TLR-mediated signalling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1860-7. [PMID: 25797518 DOI: 10.1016/j.bbamem.2015.03.014] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 12/13/2022]
Abstract
Over the last twenty years, evidence has been provided that the plasma membrane is partitioned with microdomains, laterally mobile in the bilayer, providing the necessary microenvironment to specific membrane proteins for signalling pathways to be initiated. We discuss here the importance of such microdomains for Toll-like receptors (TLR) localization and function. First, lipid microdomains favour recruitment and clustering of the TLR machinery partners, i.e. receptors and co-receptors previously identified to be required for ligand recognition and signal transmission. Further, the presence of the so-called Cholesterol Recognition Amino-Acid Consensus (CRAC) sequences in the intracellular juxtamembrane domain of several Toll-like receptors suggests a direct role of cholesterol in the activation process. This article is part of a Special Issue entitled: Lipid-protein interactions.
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Affiliation(s)
- Jean-Marie Ruysschaert
- Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium
| | - Caroline Lonez
- Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium; Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
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Płóciennikowska A, Hromada-Judycka A, Borzęcka K, Kwiatkowska K. Co-operation of TLR4 and raft proteins in LPS-induced pro-inflammatory signaling. Cell Mol Life Sci 2014; 72:557-581. [PMID: 25332099 PMCID: PMC4293489 DOI: 10.1007/s00018-014-1762-5] [Citation(s) in RCA: 501] [Impact Index Per Article: 50.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 10/01/2014] [Accepted: 10/13/2014] [Indexed: 11/28/2022]
Abstract
Toll-like receptor 4 (TLR4) is activated by lipopolysaccharide (LPS), a component of Gram-negative bacteria to induce production of pro-inflammatory mediators aiming at eradication of the bacteria. Dysregulation of the host responses to LPS can lead to a systemic inflammatory condition named sepsis. In a typical scenario, activation of TLR4 is preceded by binding of LPS to CD14 protein anchored in cholesterol- and sphingolipid-rich microdomains of the plasma membrane called rafts. CD14 then transfers the LPS to the TLR4/MD-2 complex which dimerizes and triggers MyD88- and TRIF-dependent production of pro-inflammatory cytokines and type I interferons. The TRIF-dependent signaling is linked with endocytosis of the activated TLR4, which is controlled by CD14. In addition to CD14, other raft proteins like Lyn tyrosine kinase of the Src family, acid sphingomyelinase, CD44, Hsp70, and CD36 participate in the TLR4 signaling triggered by LPS and non-microbial endogenous ligands. In this review, we summarize the current state of the knowledge on the involvement of rafts in TLR4 signaling, with an emphasis on how the raft proteins regulate the TLR4 signaling pathways. CD14-bearing rafts, and possibly CD36-rich rafts, are believed to be preferred sites of the assembly of a multimolecular complex which mediates the endocytosis of activated TLR4.
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Affiliation(s)
- Agnieszka Płóciennikowska
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093, Warsaw, Poland
| | - Aneta Hromada-Judycka
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093, Warsaw, Poland
| | - Kinga Borzęcka
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093, Warsaw, Poland
| | - Katarzyna Kwiatkowska
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093, Warsaw, Poland.
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Ciesielski F, Griffin DC, Rittig M, Moriyón I, Bonev BB. Interactions of lipopolysaccharide with lipid membranes, raft models — A solid state NMR study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1731-42. [DOI: 10.1016/j.bbamem.2013.03.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/08/2013] [Accepted: 03/28/2013] [Indexed: 01/09/2023]
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Su Y, Waring AJ, Ruchala P, Hong M. Structures of β-hairpin antimicrobial protegrin peptides in lipopolysaccharide membranes: mechanism of gram selectivity obtained from solid-state nuclear magnetic resonance. Biochemistry 2011; 50:2072-83. [PMID: 21302955 PMCID: PMC3062705 DOI: 10.1021/bi101975v] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structural basis for the gram selectivity of two disulfide-bonded β-hairpin antimicrobial peptides (AMPs) is investigated using solid-state nuclear magnetic resonance (NMR) spectroscopy. The hexa-arginine PG-1 exhibits potent activities against both gram-positive and gram-negative bacteria, while a mutant of PG-1 with only three cationic residues maintains gram-positive activity but is 30-fold less active against gram-negative bacteria. We determined the topological structure and lipid interactions of these two peptides in a lipopolysaccharide (LPS)-rich membrane that mimics the outer membrane of gram-negative bacteria and in the POPE/POPG membrane, which mimics the membrane of gram-positive bacteria. (31)P NMR line shapes indicate that both peptides cause less orientational disorder in the LPS-rich membrane than in the POPE/POPG membrane. (13)C chemical shifts and (13)C-(1)H dipolar couplings show that both peptides maintain their β-hairpin conformation in these membranes and are largely immobilized, but the mutant exhibits noticeable intermediate-time scale motion in the LPS membrane at physiological temperature, suggesting shallow insertion. Indeed, (1)H spin diffusion from lipid chains to the peptides shows that PG-1 fully inserts into the LPS-rich membrane whereas the mutant does not. The (13)C-(31)P distances between the most hydrophobically embedded Arg of PG-1 and the lipid (31)P are significantly longer in the LPS membrane than in the POPE/POPG membrane, indicating that PG-1 does not cause toroidal pore defects in the LPS membrane, in contrast to its behavior in the POPE/POPG membrane. Taken together, these data indicate that PG-1 causes transmembrane pores of the barrel-stave type in the LPS membrane, thus allowing further translocation of the peptide into the inner membrane of gram-negative bacteria to kill the cells. In comparison, the less cationic mutant cannot fully cross the LPS membrane because of weaker electrostatic attractions, thus causing weaker antimicrobial activities. Therefore, strong electrostatic attraction between the peptide and the membrane surface, ensured by having a sufficient number of Arg residues, is essential for potent antimicrobial activities against gram-negative bacteria. The data provide a rational basis for controlling gram selectivity of AMPs by adjusting the charge densities.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, IA 50011
| | - Alan J. Waring
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA 92697-4560
| | - Piotr Ruchala
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095
| | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011
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Kusumoto S, Fukase K, Shiba T. Key structures of bacterial peptidoglycan and lipopolysaccharide triggering the innate immune system of higher animals: chemical synthesis and functional studies. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:322-337. [PMID: 20431259 PMCID: PMC3417798 DOI: 10.2183/pjab.86.322] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 03/03/2010] [Indexed: 05/29/2023]
Abstract
Chemistry-based investigation is reviewed which led to identification of the active entities responsible for the immunostimulating potencies of peptidoglycan and lipopolysaccharide. Though these glycoconjugates which ubiquitously occur in wide range of bacteria as the essential components of their cell envelopes have long been known to enhance the immunological responses of higher animals, neither the precise chemical structures required nor the mechanism of their action had been [corrected] elucidated until early 1970s. Chemical synthesis of partial structures of peptidoglycan proved N-acetylmuramyl-L-alanyl-D-isoglutamine to be the minimum structure responsible for the activity and led to later identification of its receptor protein Nod2 present in animal cells. Another active partial structure of peptidoglycan, gamma-D-glutamyl-meso-diaminopimelic acid, and its receptor Nod1 were also identified as well. With regard to lipopolysaccharide, its glycolipid part named lipid A was purified and the structure studied. Chemically synthesized lipid A according to the newly elucidated structure exhibited full activity described for lipopolysaccharide known as endotoxin. Synthetic homogeneous lipid A and its structural analogues and labeled derivatives enabled precise studies of their interaction with receptor proteins and the mechanism of their action. Chemical synthesis of homogeneous partial structures of peptidoglycan and lipopolysaccharide gave unequivocal evidences for the concept that definite small molecular parts of these complex macromolecular bacterial glycoconjugates are specifically recognized by their respective receptors and trigger our defense system now widely recognized as innate immunity.
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Affiliation(s)
- Shoichi Kusumoto
- Suntory Institute for Bioorganic Research, Wakayamadai 1-1-1, Shimamotocho, Osaka, Japan.
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