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Brücksken KA, Loreto Palacio P, Hanschmann EM. Thiol Modifications in the Extracellular Space—Key Proteins in Inflammation and Viral Infection. Front Immunol 2022; 13:932525. [PMID: 35833136 PMCID: PMC9271835 DOI: 10.3389/fimmu.2022.932525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 05/23/2022] [Indexed: 11/13/2022] Open
Abstract
Posttranslational modifications (PTMs) allow to control molecular and cellular functions in response to specific signals and changes in the microenvironment of cells. They regulate structure, localization, stability, and function of proteins in a spatial and temporal manner. Among them, specific thiol modifications of cysteine (Cys) residues facilitate rapid signal transduction. In fact, Cys is unique because it contains the highly reactive thiol group that can undergo different reversible and irreversible modifications. Upon inflammation and changes in the cellular microenvironment, many extracellular soluble and membrane proteins undergo thiol modifications, particularly dithiol–disulfide exchange, S-glutathionylation, and S-nitrosylation. Among others, these thiol switches are essential for inflammatory signaling, regulation of gene expression, cytokine release, immunoglobulin function and isoform variation, and antigen presentation. Interestingly, also the redox state of bacterial and viral proteins depends on host cell-mediated redox reactions that are critical for invasion and infection. Here, we highlight mechanistic thiol switches in inflammatory pathways and infections including cholera, diphtheria, hepatitis, human immunodeficiency virus (HIV), influenza, and coronavirus disease 2019 (COVID-19).
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2
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Sato Y, Wang Y, Song Y, Geng W, Yan S, Nakamura K, Kikukawa T, Demura M, Ayabe T, Aizawa T. Potent bactericidal activity of reduced cryptdin-4 derived from its hydrophobicity and mediated by bacterial membrane disruption. Amino Acids 2022; 54:289-297. [PMID: 35037097 DOI: 10.1007/s00726-021-03115-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 11/29/2021] [Indexed: 11/28/2022]
Abstract
Defensin is a cysteine-rich antimicrobial peptide with three disulphide bonds under normal oxidative conditions. Cryptdin-4 (Crp4) is a defensin secreted by Paneth cells in the small intestine of mice, and only reduced Crp4 (Crp4red) shows activity against enteric commensal bacteria, although both oxidised Crp4 (Crp4ox) and Crp4red can kill non-commensal bacteria. To investigate the molecular factors that affect the potent antimicrobial activity of Crp4red, the bactericidal activities of Crp4ox and Crp4red, Crp4 with all Cys residues substituted with Ser peptide (6C/S-Crp4), and Crp4 with all thiol groups modified by N-ethylmaleimide (NEM-Crp4) were assessed. All peptides showed bactericidal activity against non-commensal bacteria, whereas Crp4red and NEM-Crp4 showed bactericidal activity against commensal bacteria. These potent peptides exhibited high hydrophobicity, which was strongly correlated with membrane insertion. Intriguingly, Crp4ox formed electrostatic interactions with the membrane surface of bacteria, even without exerting bactericidal activity. Moreover, the bactericidal activity of both oxidised and reduced forms of Crp4 was abolished by inhibition of electrostatic interactions; this finding suggests that Crp4red targets bacterial membranes. Finally, a liposome leakage assay against lipids extracted from commensal bacteria demonstrated a correlation with bactericidal activity. These results suggest that the potent bactericidal activity of Crp4red is derived from its hydrophobicity, and the bactericidal mechanism involves disruption of the bacterial membrane. Findings from this study provide a better understanding of the bactericidal mechanism of both Crp4ox and Crp4red.
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Affiliation(s)
- Yuji Sato
- Protein Science Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yi Wang
- Protein Science Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yuchi Song
- Protein Science Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Weiming Geng
- Protein Science Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Shaonan Yan
- Protein Science Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kiminori Nakamura
- Innate Immunity Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Takashi Kikukawa
- Laboratory of Biological Information Analysis Science, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Makoto Demura
- Laboratory of Biological Information Analysis Science, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Tokiyoshi Ayabe
- Innate Immunity Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Tomoyasu Aizawa
- Protein Science Laboratory, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan.
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3
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Jensen SK, Pærregaard SI, Brandum EP, Jørgensen AS, Hjortø GM, Jensen BAH. OUP accepted manuscript. Gastroenterol Rep (Oxf) 2022; 10:goac008. [PMID: 35291443 PMCID: PMC8915887 DOI: 10.1093/gastro/goac008] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/07/2022] [Accepted: 02/16/2022] [Indexed: 11/24/2022] Open
Abstract
Organismal survival depends on a well-balanced immune system and maintenance of host–microbe mutualism. The fine-tuned relationship between the gut microbiota and host immunity is constantly challenged by opportunistic bacteria testing the integrity of gastrointestinal (GI) barrier defenses. Barrier dysfunction reduces immunological tolerance towards otherwise innocuous microbes; it is a process that may instigate chronic inflammation. Paradoxically, sustained inflammation further diminishes barrier function, enabling bacterial translocation to extra-intestinal tissues. Once translocated, these bacteria stimulate systemic inflammation, thereby compromising organ function. While genetic risk alleles associate with barrier dysfunction, environmental stressors are key triggers of GI inflammation and associated breakdown in immune tolerance towards resident gut microbes. As dietary components dictate substrate availability, they also orchestrate microbiota composition and function, including migratory and pro-inflammatory potential, thus holding the capacity to fuel both GI and extra-intestinal inflammation. Additionally, Western diet consumption may weaken barrier defenses via curbed Paneth cell function and diminished host-defense peptide secretion. This review focuses on intervenable niches of host–microbe interactions and mucosal immunity with the ambition to provide a framework of plausible strategies to improve barrier function and regain tolerance in the inflamed mucosa via nutritional intervention.
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Affiliation(s)
- Sune K Jensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simone I Pærregaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emma P Brandum
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Astrid S Jørgensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gertrud M Hjortø
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Benjamin A H Jensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Corresponding author. Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Build. 22.5.39, Copenhagen N 2200, Denmark. Tel: +45-35330188;
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4
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Fasina YO, Obanla T, Dosu G, Muzquiz S. Significance of Endogenous Antimicrobial Peptides on the Health of Food Animals. Front Vet Sci 2021; 8:585266. [PMID: 34262957 PMCID: PMC8273337 DOI: 10.3389/fvets.2021.585266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 05/20/2021] [Indexed: 11/13/2022] Open
Abstract
Acquired resistance to in-feed antibiotic growth promoters continues to be an imperative problem in the livestock industries, thereby necessitating continuous pursuit for alternatives. Antimicrobial peptides (AMPs) represent a critical part of the host's innate immune system and have been documented to have immunomodulatory activity. Increasing research evidence suggests that in contrast to antibiotics, AMPs exert broad-spectrum antibacterial activity in a manner that reduces bacterial acquisition of resistance genes. This review summarizes current knowledge on the protective effects of endogenous (natural) AMPs in the gastrointestinal tract of food animals. Factors limiting the efficacy of these AMPs were also discussed and mitigating strategies were proposed.
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Affiliation(s)
- Yewande O Fasina
- Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC, United States
| | - Temitayo Obanla
- Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC, United States
| | - George Dosu
- Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC, United States
| | - Sierra Muzquiz
- Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC, United States
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5
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Javitt G, Kinzel A, Reznik N, Fass D. Conformational switches and redox properties of the colon cancer-associated human lectin ZG16. FEBS J 2021; 288:6465-6475. [PMID: 34077620 PMCID: PMC9291870 DOI: 10.1111/febs.16044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/16/2021] [Accepted: 06/01/2021] [Indexed: 11/30/2022]
Abstract
Zymogen granule membrane protein 16 (ZG16) is produced in organs that secrete large quantities of enzymes and other proteins into the digestive tract. ZG16 binds microbial pathogens, and lower ZG16 expression levels correlate with colorectal cancer, but the physiological function of the protein is poorly understood. One prominent attribute of ZG16 is its ability to bind glycans, but other aspects of the protein may also contribute to activity. An intriguing feature of ZG16 is a CXXC motif at the carboxy terminus. Here, we describe crystal structures and biochemical studies showing that the CXXC motif is on a flexible tail, where it contributes little to structure or stability but is available to engage in redox reactions. Specifically, we demonstrate that the ZG16 cysteine thiols can be oxidized to a disulfide by quiescin sulfhydryl oxidase 1, which is a sulfhydryl oxidase present together with ZG16 in the Golgi apparatus and in mucus, as well as by protein disulfide isomerase. ZG16 crystal structures also draw attention to a nonproline cis peptide bond that can isomerize within the protein and to the mobility of glycine‐rich loops in the glycan‐binding site. An understanding of the properties of the ZG16 CXXC motif and the discovery of internal conformational switches extend existing knowledge relating to the glycan‐binding activity of the protein.
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Affiliation(s)
- Gabriel Javitt
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Alisa Kinzel
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Nava Reznik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Deborah Fass
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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Significance of Mast Cell Formed Extracellular Traps in Microbial Defense. Clin Rev Allergy Immunol 2021; 62:160-179. [PMID: 34024033 PMCID: PMC8140557 DOI: 10.1007/s12016-021-08861-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2021] [Indexed: 02/07/2023]
Abstract
Mast cells (MCs) are critically involved in microbial defense by releasing antimicrobial peptides (such as cathelicidin LL-37 and defensins) and phagocytosis of microbes. In past years, it has become evident that in addition MCs may eliminate invading pathogens by ejection of web-like structures of DNA strands embedded with proteins known together as extracellular traps (ETs). Upon stimulation of resting MCs with various microorganisms, their products (including superantigens and toxins), or synthetic chemicals, MCs become activated and enter into a multistage process that includes disintegration of the nuclear membrane, release of chromatin into the cytoplasm, adhesion of cytoplasmic granules on the emerging DNA web, and ejection of the complex into the extracellular space. This so-called ETosis is often associated with cell death of the producing MC, and the type of stimulus potentially determines the ratio of surviving vs. killed MCs. Comparison of different microorganisms with specific elimination characteristics such as S pyogenes (eliminated by MCs only through extracellular mechanisms), S aureus (removed by phagocytosis), fungi, and parasites has revealed important aspects of MC extracellular trap (MCET) biology. Molecular studies identified that the formation of MCET depends on NADPH oxidase-generated reactive oxygen species (ROS). In this review, we summarize the present state-of-the-art on the biological relevance of MCETosis, and its underlying molecular and cellular mechanisms. We also provide an overview over the techniques used to study the structure and function of MCETs, including electron microscopy and fluorescence microscopy using specific monoclonal antibodies (mAbs) to detect MCET-associated proteins such as tryptase and histones, and cell-impermeant DNA dyes for labeling of extracellular DNA. Comparing the type and biofunction of further MCET decorating proteins with ETs produced by other immune cells may help provide a better insight into MCET biology in the pathogenesis of autoimmune and inflammatory disorders as well as microbial defense.
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7
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Milner S, Swanson E, Granick M, Sopko N. Addressing Full-Thickness Skin Defects: A Review of Clinically Available Autologous Skin Replacements. Surg Technol Int 2021; 38:73-78. [PMID: 33755940 DOI: 10.52198/21.sti.38.wh1403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Autologous keratinocyte culture, and combinations of scaffolds, different cell types, solutions of macromolecules, or growth factors have contributed to the resurfacing of full-thickness skin defects. Ideally, a treatment for full-thickness skin defects should not merely reestablish continuity of the surface of the skin but should restore its structure to allow skin to function as a dynamic biological factory that can participate in protein synthesis, metabolism, and cell signaling, and form an essential part of the body's immune, nervous, and endocrine systems. This paper provides a review of clinically available autologous skin replacements, highlighting the importance of regenerating an organ that will function physiologically.
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Affiliation(s)
- Stephen Milner
- Department of Research and Development, PolarityTE, Salt Lake City, Utah
| | - Edward Swanson
- Department of Research and Development, PolarityTE, Salt Lake City, Utah
| | - Mark Granick
- Department of Surgery, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Nikolai Sopko
- Department of Research and Development, PolarityTE, Salt Lake City, Utah
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8
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Redox Active Antimicrobial Peptides in Controlling Growth of Microorganisms at Body Barriers. Antioxidants (Basel) 2021; 10:antiox10030446. [PMID: 33805777 PMCID: PMC7998263 DOI: 10.3390/antiox10030446] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/05/2021] [Accepted: 03/09/2021] [Indexed: 01/14/2023] Open
Abstract
Epithelia in the skin, gut and other environmentally exposed organs display a variety of mechanisms to control microbial communities and limit potential pathogenic microbial invasion. Naturally occurring antimicrobial proteins/peptides and their synthetic derivatives (here collectively referred to as AMPs) reinforce the antimicrobial barrier function of epithelial cells. Understanding how these AMPs are functionally regulated may be important for new therapeutic approaches to combat microbial infections. Some AMPs are subject to redox-dependent regulation. This review aims to: (i) explore cysteine-based redox active AMPs in skin and intestine; (ii) discuss casual links between various redox environments of these barrier tissues and the ability of AMPs to control cutaneous and intestinal microbes; (iii) highlight how bacteria, through intrinsic mechanisms, can influence the bactericidal potential of redox-sensitive AMPs.
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9
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Lorenzen I, Eble JA, Hanschmann EM. Thiol switches in membrane proteins - Extracellular redox regulation in cell biology. Biol Chem 2020; 402:253-269. [PMID: 33108336 DOI: 10.1515/hsz-2020-0266] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/17/2020] [Indexed: 12/11/2022]
Abstract
Redox-mediated signal transduction depends on the enzymatic production of second messengers such as hydrogen peroxide, nitric oxide and hydrogen sulfite, as well as specific, reversible redox modifications of cysteine-residues in proteins. So-called thiol switches induce for instance conformational changes in specific proteins that regulate cellular pathways e.g., cell metabolism, proliferation, migration, gene expression and inflammation. Reduction, oxidation and disulfide isomerization are controlled by oxidoreductases of the thioredoxin family, including thioredoxins, glutaredoxins, peroxiredoxins and protein dsisulfide isomerases. These proteins are located in different cellular compartments, interact with substrates and catalyze specific reactions. Interestingly, some of these proteins are released by cells. Their extracellular functions and generally extracellular redox control have been widely underestimated. Here, we give an insight into extracellular redox signaling, extracellular thiol switches and their regulation by secreted oxidoreductases and thiol-isomerases, a topic whose importance has been scarcely studied so far, likely due to methodological limitations. We focus on the secreted redox proteins and characterized thiol switches in the ectodomains of membrane proteins, such as integrins and the metalloprotease ADAM17, which are among the best-characterized proteins and discuss their underlying mechanisms and biological implications.
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Affiliation(s)
- Inken Lorenzen
- Centre of Biochemistry and Molecular Biology, Structural Biology, Christian-Albrecht University of Kiel, Am Botanischen Garten 1-9, D-24118Kiel, Germany
| | - Johannes A Eble
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Waldeyerstr. 15, D-48149Münster, Germany
| | - Eva-Maria Hanschmann
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Life Science Center, Merowingerplatz 1a, D-40225Düsseldorf, Germany
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10
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Tanaka LY, Oliveira PVS, Laurindo FRM. Peri/Epicellular Thiol Oxidoreductases as Mediators of Extracellular Redox Signaling. Antioxid Redox Signal 2020; 33:280-307. [PMID: 31910038 DOI: 10.1089/ars.2019.8012] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Significance: Supracellular redox networks regulating cell-extracellular matrix (ECM) and organ system architecture merge with structural and functional (catalytic or allosteric) properties of disulfide bonds. This review addresses emerging evidence that exported thiol oxidoreductases (TORs), such as thioredoxin, protein disulfide isomerases (PDIs), quiescin sulfhydryl oxidases (QSOX)1, and peroxiredoxins, composing a peri/epicellular (pec)TOR pool, mediate relevant signaling. pecTOR functions depend mainly on kinetic and spatial regulation of thiol-disulfide exchange reactions governed by redox potentials, which are modulated by exported intracellular low-molecular-weight thiols, together conferring signal specificity. Recent Advances: pecTOR redox-modulates several targets including integrins, ECM proteins, surface molecules, and plasma components, although clear-cut documentation of direct effects is lacking in many cases. TOR catalytic pathways, displaying common patterns, culminate in substrate thiol reduction, oxidation, or isomerization. Peroxiredoxins act as redox/peroxide sensors, contrary to PDIs, which are likely substrate-targeted redox modulators. Emerging evidence suggests important pecTOR roles in patho(physio)logical processes, including blood coagulation, vascular remodeling, mechanosensing, endothelial function, immune responses, and inflammation. Critical Issues: Effects of pecPDIs supporting thrombosis/platelet activation have been well documented and reached the clinical arena. Roles of pecPDIA1 in vascular remodeling/mechanosensing are also emerging. Extracellular thioredoxin and pecPDIs redox-regulate immunoinflammation. Routes of TOR externalization remain elusive and appear to involve Golgi-independent routes. pecTORs are particularly accessible drug targets. Future Directions: Further understanding mechanisms of thiol redox reactions and developing assays for assessing pecTOR redox activities remain important research avenues. Also, addressing pecTORs as disease markers and achieving more efficient/specific drugs for pecTOR modulation are major perspectives for diagnostic/therapeutic improvements.
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Affiliation(s)
- Leonardo Y Tanaka
- Vascular Biology Laboratory, LIM-64 (Translational Cardiovascular Biology), Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Percillia V S Oliveira
- Vascular Biology Laboratory, LIM-64 (Translational Cardiovascular Biology), Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Francisco R M Laurindo
- Vascular Biology Laboratory, LIM-64 (Translational Cardiovascular Biology), Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil
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11
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12
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The Ancestral N-Terminal Domain of Big Defensins Drives Bacterially Triggered Assembly into Antimicrobial Nanonets. mBio 2019; 10:mBio.01821-19. [PMID: 31641083 PMCID: PMC6805989 DOI: 10.1128/mbio.01821-19] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
β-Defensins are host defense peptides controlling infections in species ranging from humans to invertebrates. However, the antimicrobial activity of most human β-defensins is impaired at physiological salt concentrations. We explored the properties of big defensins, the β-defensin ancestors, which have been conserved in a number of marine organisms, mainly mollusks. By focusing on a big defensin from oyster (Cg-BigDef1), we showed that the N-terminal domain lost during evolution toward β-defensins confers bactericidal activity to Cg-BigDef1, even at high salt concentrations. Cg-BigDef1 killed multidrug-resistant human clinical isolates of Staphylococcus aureus. Moreover, the ancestral N-terminal domain drove the assembly of the big defensin into nanonets in which bacteria are entrapped and killed. This discovery may explain why the ancestral N-terminal domain has been maintained in diverse marine phyla and creates a new path of discovery to design β-defensin derivatives active at physiological and high salt concentrations. Big defensins, ancestors of β-defensins, are composed of a β-defensin-like C-terminal domain and a globular hydrophobic ancestral N-terminal domain. This unique structure is found in a limited number of phylogenetically distant species, including mollusks, ancestral chelicerates, and early-branching cephalochordates, mostly living in marine environments. One puzzling evolutionary issue concerns the advantage for these species of having maintained a hydrophobic domain lost during evolution toward β-defensins. Using native ligation chemistry, we produced the oyster Crassostrea gigas BigDef1 (Cg-BigDef1) and its separate domains. Cg-BigDef1 showed salt-stable and broad-range bactericidal activity, including against multidrug-resistant human clinical isolates of Staphylococcus aureus. We found that the ancestral N-terminal domain confers salt-stable antimicrobial activity to the β-defensin-like domain, which is otherwise inactive. Moreover, upon contact with bacteria, the N-terminal domain drives Cg-BigDef1 assembly into nanonets that entrap and kill bacteria. We speculate that the hydrophobic N-terminal domain of big defensins has been retained in marine phyla to confer salt-stable interactions with bacterial membranes in environments where electrostatic interactions are impaired. Those remarkable properties open the way to future drug developments when physiological salt concentrations inhibit the antimicrobial activity of vertebrate β-defensins.
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Chen F, Tang Y, Zheng H, Xu Y, Wang J, Wang C. Roles of the Conserved Amino Acid Residues in Reduced Human Defensin 5: Cysteine and Arginine Are Indispensable for Its Antibacterial Action and LPS Neutralization. ChemMedChem 2019; 14:1457-1465. [DOI: 10.1002/cmdc.201900282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/21/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Fang Chen
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Yong Tang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Hong Zheng
- Department of Thoracic Surgery, Xinqiao HospitalThird Military Medical University Chongqing 400037 China
| | - Yang Xu
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Junping Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Cheng Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
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14
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Wendler J, Schroeder BO, Ehmann D, Koeninger L, Mailänder-Sánchez D, Lemberg C, Wanner S, Schaller M, Stange EF, Malek NP, Weidenmaier C, LeibundGut-Landmann S, Wehkamp J. Proteolytic Degradation of reduced Human Beta Defensin 1 generates a Novel Antibiotic Octapeptide. Sci Rep 2019; 9:3640. [PMID: 30842543 PMCID: PMC6403363 DOI: 10.1038/s41598-019-40216-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 02/07/2019] [Indexed: 01/06/2023] Open
Abstract
Microbial resistance against clinical used antibiotics is on the rise. Accordingly, there is a high demand for new innovative antimicrobial strategies. The host-defense peptide human beta-defensin 1 (hBD-1) is produced continuously by epithelial cells and exhibits compelling antimicrobial activity after reduction of its disulphide bridges. Here we report that proteolysis of reduced hBD-1 by gastrointestinal proteases as well as human duodenal secretions produces an eight-amino acid carboxy-terminal fragment. The generated octapeptide retains antibiotic activity, yet with distinct characteristics differing from the full-length peptide. We modified the octapeptide by stabilizing its termini and by using non-natural D-amino acids. The native and modified peptide variants showed antibiotic activity against pathogenic as well as antibiotic-resistant microorganisms, including E. coli, P. aeruginosa and C. albicans. Moreover, in an in vitro C. albicans infection model the tested peptides demonstrated effective amelioration of C. albicans infection without showing cytotoxity on human cells. In summary, protease degradation of hBD-1 provides a yet unknown mechanism to broaden antimicrobial host defense, which could be used to develop defensin-derived therapeutic applications.
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Affiliation(s)
- Judith Wendler
- Department of Internal Medicine 1, University Hospital Tuebingen, Tuebingen, Germany
| | - Bjoern O Schroeder
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart and University of Tuebingen, Tuebingen, Germany.,Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Dirk Ehmann
- Department of Internal Medicine 1, University Hospital Tuebingen, Tuebingen, Germany
| | - Louis Koeninger
- Department of Internal Medicine 1, University Hospital Tuebingen, Tuebingen, Germany
| | | | - Christina Lemberg
- Institute of Dermatology, University Hospital Tuebingen, Tuebingen, Germany.,Institute of Immunology, Vetsuisse Faculty, University of Zürich, Zurich, Switzerland
| | - Stephanie Wanner
- Institute of Dermatology, University Hospital Tuebingen, Tuebingen, Germany.,Institute of Medical Microbiology and Hygiene, University Hospital Tuebingen, Tuebingen, Germany
| | - Martin Schaller
- Institute of Dermatology, University Hospital Tuebingen, Tuebingen, Germany
| | - Eduard F Stange
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart and University of Tuebingen, Tuebingen, Germany
| | - Nisar P Malek
- Department of Internal Medicine 1, University Hospital Tuebingen, Tuebingen, Germany
| | - Christopher Weidenmaier
- Institute of Medical Microbiology and Hygiene, University Hospital Tuebingen, Tuebingen, Germany
| | | | - Jan Wehkamp
- Department of Internal Medicine 1, University Hospital Tuebingen, Tuebingen, Germany.
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Pillai MR, Mihi B, Ishiwata K, Nakamura K, Sakuragi N, Finkelstein DB, McGargill MA, Nakayama T, Ayabe T, Coleman ML, Bix M. Myc-induced nuclear antigen constrains a latent intestinal epithelial cell-intrinsic anthelmintic pathway. PLoS One 2019; 14:e0211244. [PMID: 30807587 PMCID: PMC6391002 DOI: 10.1371/journal.pone.0211244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 01/09/2019] [Indexed: 01/06/2023] Open
Abstract
Expulsion of parasitic gastrointestinal nematodes requires diverse effector mechanisms coordinated by a Th2-type response. The evolutionarily conserved JmjC protein; Myc Induced Nuclear Antigen (Mina) has been shown to repress IL4, a key Th2 cytokine, suggesting Mina may negatively regulate nematode expulsion. Here we report that expulsion of the parasitic nematode Trichuris muris was indeed accelerated in Mina deficient mice. Unexpectedly, this was associated not with an elevated Th2- but rather an impaired Th1-type response. Further reciprocal bone marrow chimera and conditional KO experiments demonstrated that retarded parasite expulsion and a normal Th1-type response both required Mina in intestinal epithelial cells (IECs). Transcriptional profiling experiments in IECs revealed anti-microbial α-defensin peptides to be the major target of Mina-dependent retention of worms in infected mice. In vitro exposure to recombinant α-defensin peptides caused cytotoxic damage to whipworms. These results identify a latent IEC-intrinsic anthelmintic pathway actively constrained by Mina and point to α-defensins as important effectors that together with Mina may be attractive therapeutic targets for the control of nematode infection.
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Affiliation(s)
- Meenu R Pillai
- St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Belgacem Mihi
- Department of Innovative Medicine, Graduate School of Medicine and Institute for Global Prominent Research, Chiba University, Chiba, Japan
| | - Kenji Ishiwata
- Department of Tropical Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Kiminori Nakamura
- Department of Cell Biological Science, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Naoya Sakuragi
- Department of Cell Biological Science, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - David B Finkelstein
- St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Maureen A McGargill
- St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Toshinori Nakayama
- Department of Immunology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Tokiyoshi Ayabe
- Department of Cell Biological Science, Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Mathew L Coleman
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Mark Bix
- Department of Innovative Medicine, Graduate School of Medicine and Institute for Global Prominent Research, Chiba University, Chiba, Japan
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Paneth cell α-defensins HD-5 and HD-6 display differential degradation into active antimicrobial fragments. Proc Natl Acad Sci U S A 2019; 116:3746-3751. [PMID: 30808760 PMCID: PMC6397583 DOI: 10.1073/pnas.1817376116] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Paneth cells provide intestinal host defense against pathogens and control the healthy microbiota by secreting antimicrobial peptides. We show that the most abundant secreted Paneth cell products, human defensin HD-5 and HD-6, show a distinct susceptibility to proteolytic digestion by human duodenal fluid. While HD-5 is digested in many fragments, HD-6 is stable and still able to form nanonets. The occurring fragments of HD-5 were antimicrobially active against microorganisms. We provide proof of concept about microbiome modulating capacities in vivo, which includes an increase of Akkermansia sp. Our results indicate that fragmentation of defensins increases antimicrobial diversity and further adds to the complexity of host microbial interaction at interfaces. Fragmentation could lead to new antimicrobial peptides with possible therapeutic usage. Antimicrobial peptides, in particular α-defensins expressed by Paneth cells, control microbiota composition and play a key role in intestinal barrier function and homeostasis. Dynamic conditions in the local microenvironment, such as pH and redox potential, significantly affect the antimicrobial spectrum. In contrast to oxidized peptides, some reduced defensins exhibit increased vulnerability to proteolytic degradation. In this report, we investigated the susceptibility of Paneth-cell–specific human α-defensin 5 (HD-5) and -6 (HD-6) to intestinal proteases using natural human duodenal fluid. We systematically assessed proteolytic degradation using liquid chromatography–mass spectrometry and identified several active defensin fragments capable of impacting bacterial growth of both commensal and pathogenic origins. Of note, incubation of mucus with HD-5 resulted in 255–8,000 new antimicrobial combinations. In contrast, HD-6 remained stable with consistent preserved nanonet formation. In vivo studies demonstrated proof of concept that a HD-5 fragment shifted microbiota composition (e.g., increases of Akkermansia sp.) without decreasing diversity. Our data support the concept that secretion of host peptides results in an environmentally dependent increase of antimicrobial defense by clustering in active peptide fragments. This complex clustering mechanism dramatically increases the host’s ability to control pathogens and commensals. These findings broaden our understanding of host modulation of the microbiome as well as the complexity of human mucosal defense mechanisms, thus providing promising avenues to explore for drug development.
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17
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Klag T, Courth L, Ostaff MJ, Ott G, Stange EF, Malek NP, Seifarth W, Wehkamp J. Human Endogenous Retroviruses: Residues of Ancient Times Are Differentially Expressed in Crohn's Disease. Inflamm Intest Dis 2018; 3:125-137. [PMID: 30820434 DOI: 10.1159/000494026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 09/22/2018] [Indexed: 12/12/2022] Open
Abstract
Background Eight percent of the human genome consists of human endogenous retroviruses (HERV). These genetic elements are remnants of ancient retroviral germ-line infections. Altered HERV expression is associated with several chronic inflammatory diseases. A physiological role of the HERV-derived proteins syncytin-1 and -2 has been described for the integrity of the human placental cell layer in terms of maintaining feto-maternal tolerance. The aim of this project was to investigate HERV expression in Crohn's disease (CD) with a further focus on syncytins in the gut. Material and Methods Seventy-four ileal and colonic tissue samples of CD patients and healthy controls have been investigated for mRNA expression of major HERV groups by a comprehensive microarray screening. The most prominent differences have been validated by qRT-PCR. Immunohistochemistry (IHC), Western Blot (WB) and qRT-PCR were performed for syncytin-1 and -2. Results HERV microarray screening revealed a distinct expression profile in ileal and colonic tissue, as well as differential expression in CD compared to healthy controls. qRT-PCR validated differential expression of at least 3 HERV-groups in CD. qRT-PCR, IHC and WB showed a tissue-dependent diminished epithelial expression of syncytins in inflamed CD. Conclusion For the first time, HERV expression has been comprehensively studied in the gut. Between CD and healthy controls we could show a tissue dependent differential HERV expression profile. Notably, we could show that syncytin-1 and -2 are expressed in the epithelial layer in ileal and colonic tissue samples, whereas their diminished tissue-dependent expression in inflamed CD might modulate inflammatory processes at the gut barrier.
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Affiliation(s)
- Thomas Klag
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Lioba Courth
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Maureen J Ostaff
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
| | - German Ott
- Department of Pathology, Robert-Bosch-Hospital, Stuttgart, Germany
| | - Eduard F Stange
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Nisar P Malek
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Wolfgang Seifarth
- Department of Internal Medicine III, University of Heidelberg, University Hospital Mannheim, Mannheim, Germany
| | - Jan Wehkamp
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
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Álvarez ÁH, Martínez Velázquez M, Prado Montes de Oca E. Human β-defensin 1 update: Potential clinical applications of the restless warrior. Int J Biochem Cell Biol 2018; 104:133-137. [PMID: 30236992 DOI: 10.1016/j.biocel.2018.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/15/2018] [Accepted: 09/15/2018] [Indexed: 01/06/2023]
Abstract
Human β-defensin 1 (hBD-1) is a multifaceted antimicrobial peptide being a tumour suppressor and, depending on call of duty, capable of inducing self-nets and neutrophil extracellular traps (NETs) to capture and/or kill bacteria, participates in inflammatory responses in chronic diseases including hBD-3 upregulation and also capable of up/downregulation in the presence of certain species of Lactobacillus sp. Thus, is regulated by host microbiota. Alleles, genotypes and/or altered gene expression of its coding gene, DEFB1, have been associated with several human diseases/conditions ranging from metabolic/chronic (e.g. cancer), infectious (e.g. tuberculosis, HIV/AIDS), inflammatory (gastrointestinal diseases), male infertility and more recently, neurologic (e.g. depression and Alzheimer) and autoimmune diseases (e.g. vitiligo and systemic lupus erythematosus). The present update focuses on novel DEFB1/hBD-1 properties and biomarker features, its biological function and the pharmaceutical potential uses of antimicrobial peptide elicitors (APEs) or the engineered peptide in the treatment of hBD-1-related human diseases.
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Affiliation(s)
- Ángel H Álvarez
- Personalized Medicine National Laboratory (LAMPER), Medical and Pharmaceutical Biotechnology Unit, Research Center of Technology and Design Assistance of Jalisco State (CIATEJ), National Council of Science and Technology (CONACYT), Av. Normalistas 800, Col. Colinas de la Normal, Guadalajara, Mexico
| | - Moisés Martínez Velázquez
- Personalized Medicine National Laboratory (LAMPER), Medical and Pharmaceutical Biotechnology Unit, Research Center of Technology and Design Assistance of Jalisco State (CIATEJ), National Council of Science and Technology (CONACYT), Av. Normalistas 800, Col. Colinas de la Normal, Guadalajara, Mexico
| | - Ernesto Prado Montes de Oca
- Personalized Medicine National Laboratory (LAMPER), Medical and Pharmaceutical Biotechnology Unit, Research Center of Technology and Design Assistance of Jalisco State (CIATEJ), National Council of Science and Technology (CONACYT), Av. Normalistas 800, Col. Colinas de la Normal, Guadalajara, Mexico.
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19
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Klag T, Thomas M, Ehmann D, Courth L, Mailänder-Sanchez D, Weiss TS, Dayoub R, Abshagen K, Vollmar B, Thasler WE, Stange EF, Berg CP, Malek NP, Zanger UM, Wehkamp J. β-Defensin 1 Is Prominent in the Liver and Induced During Cholestasis by Bilirubin and Bile Acids via Farnesoid X Receptor and Constitutive Androstane Receptor. Front Immunol 2018; 9:1735. [PMID: 30100908 PMCID: PMC6072844 DOI: 10.3389/fimmu.2018.01735] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 07/13/2018] [Indexed: 12/12/2022] Open
Abstract
Background & aims Knowledge about innate antimicrobial defense of the liver is limited. We investigated hepatic expression and regulation of antimicrobial peptides with focus on the human beta defensin-1 (hBD-1). Methods Radial diffusion assay was used to analyze antimicrobial activity of liver tissue. Different defensins including hBD-1 and its activator thioredoxin-1 (TXN) were analyzed in healthy and cholestatic liver samples by qPCR and immunostaining. Regulation of hBD-1 expression was studied in vitro and in vivo using bile duct-ligated mice. Regulation of hBD-1 via bilirubin and bile acids (BAs) was studied using siRNA. Results We found strong antimicrobial activity of liver tissue against Escherichia coli. As a potential mediator of this antimicrobial activity we detected high expression of hBD-1 and TXN in hepatocytes, whereas other defensins were minimally expressed. Using a specific antibody for the reduced, antimicrobially active form of hBD-1 we found hBD-1 in co-localization with TXN within hepatocytes. hBD-1 was upregulated in cholestasis in a graded fashion. In cholestatic mice hepatic AMP expression (Defb-1 and Hamp) was enhanced. Bilirubin and BAs were able to induce hBD-1 in hepatic cell cultures in vitro. Treatment with siRNA and/or agonists demonstrated that the farnesoid X receptor (FXR) mediates basal expression of hBD-1, whereas both constitutive androstane receptor (CAR) and FXR seem to be responsible for the induction of hBD-1 by bilirubin. Conclusion hBD-1 is prominently expressed in hepatocytes. It is induced during cholestasis through bilirubin and BAs, mediated by CAR and especially FXR. Reduction by TXN activates hBD-1 to a potential key player in innate antimicrobial defense of the liver.
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Affiliation(s)
- Thomas Klag
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Maria Thomas
- Dr. Margarete Fischer-Bosch Institute for Clinical Pharmacology, Stuttgart and University of Tuebingen, Tuebingen, Germany
| | - Dirk Ehmann
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Lioba Courth
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | | | - Thomas S Weiss
- University Children Hospital (KUNO), Regensburg University Hospital, Regensburg, Germany
| | - Rania Dayoub
- University Children Hospital (KUNO), Regensburg University Hospital, Regensburg, Germany
| | - Kerstin Abshagen
- Rudolf-Zenker-Institute for Experimental Surgery, University Medicine Rostock, Rostock, Germany
| | - Brigitte Vollmar
- Rudolf-Zenker-Institute for Experimental Surgery, University Medicine Rostock, Rostock, Germany
| | - Wolfgang E Thasler
- Department of Surgery, Grosshadern Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Eduard F Stange
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Christoph P Berg
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Nisar P Malek
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
| | - Ulrich M Zanger
- Dr. Margarete Fischer-Bosch Institute for Clinical Pharmacology, Stuttgart and University of Tuebingen, Tuebingen, Germany
| | - Jan Wehkamp
- Department of Internal Medicine I, University of Tübingen, Tübingen, Germany
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20
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Bacterial Periplasmic Oxidoreductases Control the Activity of Oxidized Human Antimicrobial β-Defensin 1. Infect Immun 2018; 86:IAI.00875-17. [PMID: 29378796 DOI: 10.1128/iai.00875-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/18/2018] [Indexed: 12/21/2022] Open
Abstract
The antimicrobial peptide human β-defensin 1 (hBD1) is continuously produced by epithelial cells in many tissues. Compared to other defensins, hBD1 has only minor antibiotic activity in its native state. After reduction of its disulfide bridges, however, it becomes a potent antimicrobial agent against bacteria, while the oxidized native form (hBD1ox) shows specific activity against Gram-negative bacteria. We show that the killing mechanism of hBD1ox depends on aerobic growth conditions and bacterial enzymes. We analyzed the different activities of hBD1 using mutants of Escherichia coli lacking one or more specific proteins of their outer membrane, cytosol, or redox systems. We discovered that DsbA and DsbB are essential for the antimicrobial activity of hBD1ox but not for that of reduced hBD1 (hBD1red). Furthermore, our results strongly suggest that hBD1ox uses outer membrane protein FepA to penetrate the bacterial periplasm space. In contrast, other bacterial proteins in the outer membrane and cytosol did not modify the antimicrobial activity. Using immunogold labeling, we identified the localization of hBD1ox in the periplasmic space and partly in the outer membrane of E. coli However, in resistant mutants lacking DsbA and DsbB, hBD1ox was detected mainly in the bacterial cytosol. In summary, we discovered that hBD1ox could use FepA to enter the periplasmic space, where its activity depends on presence of DsbA and DsbB. HBD1ox concentrates in the periplasm in Gram-negative bacteria, which finally leads to bleb formation and death of the bacteria. Thus, the bacterial redox system plays an essential role in mechanisms of resistance against host-derived peptides such as hBD1.
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21
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Colgan SP, Campbell EL. Oxygen metabolism and innate immune responses in the gut. J Appl Physiol (1985) 2017; 123:1321-1327. [PMID: 28705991 DOI: 10.1152/japplphysiol.00113.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/27/2017] [Accepted: 07/06/2017] [Indexed: 01/02/2023] Open
Abstract
Epithelial cells of the mucosa provide a first line of defense to prevent the inappropriate translocation of luminal antigens, and therefore contribute significantly to nonspecific innate immunity. In the gastrointestinal (GI) tract, barrier is provided by multiple components of the mucosa, including mucus production, epithelial junctional complexes, and the production of antimicrobial molecules. In recent years, it is better appreciated that tissue oxygen metabolism is key to homeostasis in the mucosa. The intestine, for example, maintains a low baseline Po2 level due to high rates of metabolism, countercurrent blood flow, and the presence of a steep oxygen gradient across the luminal aspect of tissue surface. As a result, hypoxia and hypoxia-inducible factor (HIF)-dependent signaling exists even in the healthy, unperturbed intestinal mucosa. In a number of examples, HIF has been demonstrated both to promote barrier function during homeostasis and to promote resolution of active inflammation. Hypoxia-elicited factors that contribute to innate responses in the mucosa include the transcriptional regulation of mucin genes, junction proteins, and autophagic flux. Here, we review current literature related to hypoxia and innate immunity in health and during mucosal inflammation.
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Affiliation(s)
- Sean P Colgan
- Department of Medicine and the Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado; and
| | - Eric L Campbell
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
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22
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Park SC, Kim YM, Lee JK, Kim NH, Kim EJ, Heo H, Lee MY, Lee JR, Jang MK. Targeting and synergistic action of an antifungal peptide in an antibiotic drug-delivery system. J Control Release 2017; 256:46-55. [DOI: 10.1016/j.jconrel.2017.04.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/29/2017] [Accepted: 04/17/2017] [Indexed: 10/19/2022]
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23
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Raschig J, Mailänder-Sánchez D, Berscheid A, Berger J, Strömstedt AA, Courth LF, Malek NP, Brötz-Oesterhelt H, Wehkamp J. Ubiquitously expressed Human Beta Defensin 1 (hBD1) forms bacteria-entrapping nets in a redox dependent mode of action. PLoS Pathog 2017; 13:e1006261. [PMID: 28323883 PMCID: PMC5376342 DOI: 10.1371/journal.ppat.1006261] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/31/2017] [Accepted: 02/26/2017] [Indexed: 11/19/2022] Open
Abstract
Ever since the discovery of endogenous host defense antimicrobial peptides it has been discussed how these evolutionary conserved molecules avoid to induce resistance and to remain effective. Human ß-defensin 1 (hBD1) is an ubiquitously expressed endogenous antimicrobial peptide that exhibits qualitatively distinct activities between its oxidized and reduced forms. Here, we explore these antimicrobial mechanisms. Surprisingly, using electron microscopy we detected a so far unknown net-like structure surrounding bacteria, which were treated with the reduced but not the oxidized form of hBD1. A transmigration assay demonstrated that hBD1-derived nets capture bacteria and inhibit bacterial transmigration independent of bacterial killing. The presence of nets could completely prevent migration of hBD1 resistant pathogens and are stable in the presence of human duodenal secretion with a high amount of proteases. In contrast to HD6, cysteins are necessary for net formation. This redox-dependent function serves as an additional mechanism of action for hBD1 and differs from net formation by other defensins such as Paneth cell-derived human α-defensin 6 (HD6). While hBD1red and hBD1ox have distinct antimicrobial profiles and functions, only the reduced form provides additional host protection by entrapping bacteria in extracellular net structures preventing bacterial invasion. Better understanding of the modes of action of endogenous host peptides will help to find new antimicrobial strategies.
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Affiliation(s)
- Judith Raschig
- Internal Medicine I, University Hospital Tuebingen, Tuebingen, Germany
| | | | - Anne Berscheid
- Department for Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Germany
| | - Jürgen Berger
- Max-Planck Institute for Developmental Biology, Electron Microscopy, Tuebingen, Germany
| | - Adam A. Strömstedt
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, Uppsala, Sweden
| | - Lioba F. Courth
- Internal Medicine I, University Hospital Tuebingen, Tuebingen, Germany
| | - Nisar P. Malek
- Internal Medicine I, University Hospital Tuebingen, Tuebingen, Germany
| | - Heike Brötz-Oesterhelt
- Department for Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Germany
| | - Jan Wehkamp
- Internal Medicine I, University Hospital Tuebingen, Tuebingen, Germany
- * E-mail:
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24
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Glover LE, Lee JS, Colgan SP. Oxygen metabolism and barrier regulation in the intestinal mucosa. J Clin Invest 2016; 126:3680-3688. [PMID: 27500494 DOI: 10.1172/jci84429] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mucosal surfaces are lined by epithelial cells and provide an important barrier to the flux of antigens from the outside. This barrier is provided at a number of levels, including epithelial junctional complexes, mucus production, and mucosa-derived antimicrobials. Tissue metabolism is central to the maintenance of homeostasis in the mucosa. In the intestine, for example, baseline pO2 levels are uniquely low due to counter-current blood flow and the presence of large numbers of bacteria. As such, hypoxia and HIF signaling predominates normal intestinal metabolism and barrier regulation during both homeostasis and active inflammation. Contributing factors that elicit important adaptive responses within the mucosa include the transcriptional regulation of tight junction proteins, metabolic regulation of barrier components, and changes in autophagic flux. Here, we review recent literature around the topic of hypoxia and barrier function in health and during disease.
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25
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Abstract
Disulfide bonds represent versatile posttranslational modifications whose roles encompass the structure, catalysis, and regulation of protein function. Due to the oxidizing nature of the extracellular environment, disulfide bonds found in secreted proteins were once believed to be inert. This notion has been challenged by the discovery of redox-sensitive disulfides that, once cleaved, can lead to changes in protein activity. These functional disulfides are twisted into unique configurations, leading to high strain and potential energy. In some cases, cleavage of these disulfides can lead to a gain of function in protein activity. Thus, these motifs can be referred to as switches. We describe the couples that control redox in the extracellular environment, examine several examples of proteins with switchable disulfides, and discuss the potential applications of disulfides in molecular biology.
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Affiliation(s)
- Michael C Yi
- Department of Chemical Engineering, Stanford University, Stanford, California 94305; ,
| | - Chaitan Khosla
- Department of Chemical Engineering, Stanford University, Stanford, California 94305; , .,Department of Chemistry, Stanford University, Stanford, California 94305
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26
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Reduction Impairs the Antibacterial Activity but Benefits the LPS Neutralization Ability of Human Enteric Defensin 5. Sci Rep 2016; 6:22875. [PMID: 26960718 PMCID: PMC4785407 DOI: 10.1038/srep22875] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 02/22/2016] [Indexed: 01/01/2023] Open
Abstract
Oxidized human defensin 5 (HD5OX), a Paneth cell-secreted antibacterial peptide with three characteristic disulfide bonds, protects the host from invasion by morbigenous microbes in the small intestine. HD5OX can be reduced by thioredoxin (Trx) in vitro, while the biochemical properties of the reduced linear peptide, HD5RED, remain unclear. Here, we first confirm that HD5RED does exist in vivo. Furthermore, we reveal that the recruitment of HD5RED to the outer membrane of Gram-negative bacteria and to the anionic lipid A is lower than that of HD5OX, and HD5RED is less efficient in penetrating bacterial outer and inner membranes and inducing membrane depolarization, which confers an attenuated antibacterial activity to HD5RED. However, due to its higher structural flexibility, the binding of HD5RED to bacterial lipopolysaccharide (LPS) is markedly stronger than that of HD5OX. Consequently, HD5RED is more effective in suppressing the production of the pro-inflammatory cytokine TNF-α in LPS-stimulated macrophages by blocking the interaction between LPS and LPS-binding protein, thus suggesting that HD5RED might act as a scavenger to neutralize LPS in the gut. This study provides insights into the antibacterial and immunoregulatory effects of HD5RED and expands the known repertoire of the enteric defensins.
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27
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Güncü GN, Yilmaz D, Könönen E, Gürsoy UK. Salivary Antimicrobial Peptides in Early Detection of Periodontitis. Front Cell Infect Microbiol 2015; 5:99. [PMID: 26734583 PMCID: PMC4689996 DOI: 10.3389/fcimb.2015.00099] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/11/2015] [Indexed: 12/16/2022] Open
Abstract
In the pathogenesis of periodontitis, an infection-induced inflammatory disease of the tooth-supporting tissues, there is a complex interaction between the subgingival microbiota and host tissues. A periodontal diagnostic tool for detecting the initiation and progression of the disease, monitoring the response to therapy, or measuring the degree of susceptibility to future disease progression has been of interest for a long time. The value of various enzymes, proteins, and immunoglobulins, which are abundant constituents of saliva, as potential biomarkers has been recognized and extensively investigated for periodontal diseases. Gingival defensins and cathelicidins are small cationic antimicrobial peptides that play an important role in innate immune response. However, their applicability as salivary biomarkers is still under debate. The present review focuses on proteomic biomarkers and antimicrobial peptides, in particular, to be used at early phases of periodontitis.
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Affiliation(s)
- Güliz N Güncü
- Faculty of Dentistry, University of Hacettepe Ankara, Turkey
| | - Dogukan Yilmaz
- Faculty of Dentistry, University of Istanbul Medipol Istanbul, Turkey
| | - Eija Könönen
- Periodontology, Institute of Dentistry, University of TurkuTurku, Finland; Welfare Division, Oral Health CareTurku, Finland
| | - Ulvi K Gürsoy
- Periodontology, Institute of Dentistry, University of Turku Turku, Finland
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28
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Adamczyk M, Griffiths R, Dewitt S, Knäuper V, Aeschlimann D. P2X7 receptor activation regulates rapid unconventional export of transglutaminase-2. J Cell Sci 2015; 128:4615-28. [PMID: 26542019 PMCID: PMC4696497 DOI: 10.1242/jcs.175968] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/29/2015] [Indexed: 12/24/2022] Open
Abstract
Transglutaminases (denoted TG or TGM) are externalized from cells via an unknown unconventional secretory pathway. Here, we show for the first time that purinergic signaling regulates active secretion of TG2 (also known as TGM2), an enzyme with a pivotal role in stabilizing extracellular matrices and modulating cell–matrix interactions in tissue repair. Extracellular ATP promotes TG2 secretion by macrophages, and this can be blocked by a selective antagonist against the purinergic receptor P2X7 (P2X7R, also known as P2RX7). Introduction of functional P2X7R into HEK293 cells is sufficient to confer rapid, regulated TG2 export. By employing pharmacological agents, TG2 release could be separated from P2X7R-mediated microvesicle shedding. Neither Ca2+ signaling alone nor membrane depolarization triggered TG2 secretion, which occurred only upon receptor membrane pore formation and without pannexin channel involvement. A gain-of-function mutation in P2X7R associated with autoimmune disease caused enhanced TG2 externalization from cells, and this correlated with increased pore activity. These results provide a mechanistic explanation for a link between active TG2 secretion and inflammatory responses, and aberrant enhanced TG2 activity in certain autoimmune conditions. Summary: Purinergic signaling regulates unconventional secretion of transglutaminase-2 (TG2) and explains the link between aberrant protein modifications and inflammatory responses in TG2-dependent autoimmunity.
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Affiliation(s)
- Magdalena Adamczyk
- Matrix Biology & Tissue Repair Research Unit and Arthritis Research UK Biomechanics and Bioengineering Center of Excellence, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK
| | - Rhiannon Griffiths
- Matrix Biology & Tissue Repair Research Unit and Arthritis Research UK Biomechanics and Bioengineering Center of Excellence, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK
| | - Sharon Dewitt
- Matrix Biology & Tissue Repair Research Unit and Arthritis Research UK Biomechanics and Bioengineering Center of Excellence, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK
| | - Vera Knäuper
- Matrix Biology & Tissue Repair Research Unit and Arthritis Research UK Biomechanics and Bioengineering Center of Excellence, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK
| | - Daniel Aeschlimann
- Matrix Biology & Tissue Repair Research Unit and Arthritis Research UK Biomechanics and Bioengineering Center of Excellence, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK
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29
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Zheng L, Kelly CJ, Colgan SP. Physiologic hypoxia and oxygen homeostasis in the healthy intestine. A Review in the Theme: Cellular Responses to Hypoxia. Am J Physiol Cell Physiol 2015; 309:C350-60. [PMID: 26179603 DOI: 10.1152/ajpcell.00191.2015] [Citation(s) in RCA: 295] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In recent years, the intestinal mucosa has proven to be an intriguing organ to study tissue oxygenation. The highly vascularized lamina propria juxtaposed to an anaerobic lumen containing trillions of metabolically active microbes results in one of the most austere tissue microenvironments in the body. Studies to date have determined that a healthy mucosa contains a steep oxygen gradient along the length of the intestine and from the lumen to the serosa. Advances in technology have allowed multiple independent measures and indicate that, in the healthy mucosa of the small and large intestine, the lumen-apposed epithelia experience Po2 conditions of <10 mmHg, so-called physiologic hypoxia. This unique physiology results from a combination of factors, including countercurrent exchange blood flow, fluctuating oxygen demands, epithelial metabolism, and oxygen diffusion into the lumen. Such conditions result in the activation of a number of hypoxia-related signaling processes, including stabilization of the transcription factor hypoxia-inducible factor. Here, we review the principles of mucosal oxygen delivery, metabolism, and end-point functional responses that result from this unique oxygenation profile.
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Affiliation(s)
- Leon Zheng
- Department of Medicine and Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Caleb J Kelly
- Department of Medicine and Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Sean P Colgan
- Department of Medicine and Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
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30
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Schroeder BO, Ehmann D, Precht JC, Castillo PA, Küchler R, Berger J, Schaller M, Stange EF, Wehkamp J. Paneth cell α-defensin 6 (HD-6) is an antimicrobial peptide. Mucosal Immunol 2015; 8:661-71. [PMID: 25354318 PMCID: PMC4424388 DOI: 10.1038/mi.2014.100] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 09/21/2014] [Indexed: 02/04/2023]
Abstract
Defensins protect human barriers from commensal and pathogenic microorganisms. Human α-defensin 6 (HD-6) is produced exclusively by small intestinal Paneth cells but, in contrast to other antimicrobial peptides (AMPs) for HD-6, no direct antibacterial killing activity has been detected so far. Herein, we systematically tested how environmental factors, like pH and reducing conditions, affect antimicrobial activity of different defensins against anaerobic bacteria of the human intestinal microbiota. Remarkably, by mimicking the intestinal milieu we detected for the first time antibacterial activity of HD-6. Activity was observed against anaerobic gut commensals but not against some pathogenic strains. Antibiotic activity was attributable to the reduced peptide and independent of free cysteines or a conserved histidine residue. Furthermore, the oxidoreductase thioredoxin, which is also expressed in Paneth cells, is able to reduce a truncated physiological variant of HD-6. Ultrastructural analyses revealed that reduced HD-6 causes disintegration of cytoplasmic structures and alterations in the bacterial cell envelope, while maintaining extracellular net-like structures. We conclude that HD-6 is an antimicrobial peptide. Our data suggest two distinct antimicrobial mechanisms by one peptide: HD-6 kills specific microbes depending on the local environmental conditions, whereas known microbial trapping by extracellular net structures is independent of the reducing milieu.
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Affiliation(s)
- B O Schroeder
- Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany,University of Tuebingen, Tuebingen, Germany,Department of Microbiology and Immunology, School of Medicine, University of California, Davis, California, USA
| | - D Ehmann
- Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany,University of Tuebingen, Tuebingen, Germany
| | - J C Precht
- Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany,University of Tuebingen, Tuebingen, Germany
| | - P A Castillo
- Department of Microbiology and Immunology, School of Medicine, University of California, Davis, California, USA
| | - R Küchler
- Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany,University of Tuebingen, Tuebingen, Germany
| | - J Berger
- Max-Planck-Institute for Developmental Biology, Electron Microscopy Unit, Tuebingen, Germany
| | - M Schaller
- Department of Dermatology, University Hospital Tuebingen, Tuebingen, Germany
| | - E F Stange
- Department of Internal Medicine I, Robert Bosch Hospital, Stuttgart, Germany
| | - J Wehkamp
- Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany,University of Tuebingen, Tuebingen, Germany,Department of Internal Medicine I, Robert Bosch Hospital, Stuttgart, Germany,Department of Internal Medicine I, University Hospital Tuebingen, Tuebingen, Germany,()
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31
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Koper T, Polit A, Sobiecka-Szkatula A, Wegrzyn K, Scire A, Figaj D, Kadzinski L, Zarzecka U, Zurawa-Janicka D, Banecki B, Lesner A, Tanfani F, Lipinska B, Skorko-Glonek J. Analysis of the link between the redox state and enzymatic activity of the HtrA (DegP) protein from Escherichia coli. PLoS One 2015; 10:e0117413. [PMID: 25710793 PMCID: PMC4339722 DOI: 10.1371/journal.pone.0117413] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 12/22/2014] [Indexed: 11/19/2022] Open
Abstract
Bacterial HtrAs are proteases engaged in extracytoplasmic activities during stressful conditions and pathogenesis. A model prokaryotic HtrA (HtrA/DegP from Escherichia coli) requires activation to cleave its substrates efficiently. In the inactive state of the enzyme, one of the regulatory loops, termed LA, forms inhibitory contacts in the area of the active center. Reduction of the disulfide bond located in the middle of LA stimulates HtrA activity in vivo suggesting that this S-S bond may play a regulatory role, although the mechanism of this stimulation is not known. Here, we show that HtrA lacking an S-S bridge cleaved a model peptide substrate more efficiently and exhibited a higher affinity for a protein substrate. An LA loop lacking the disulfide was more exposed to the solvent; hence, at least some of the interactions involving this loop must have been disturbed. The protein without S-S bonds demonstrated lower thermal stability and was more easily converted to a dodecameric active oligomeric form. Thus, the lack of the disulfide within LA affected the stability and the overall structure of the HtrA molecule. In this study, we have also demonstrated that in vitro human thioredoxin 1 is able to reduce HtrA; thus, reduction of HtrA can be performed enzymatically.
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Affiliation(s)
- Tomasz Koper
- Department of Biochemistry, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Agnieszka Polit
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Krakow, Poland
| | | | - Katarzyna Wegrzyn
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Andrea Scire
- Department of Life and Environmental Sciences, Universita Politecnica delle Marche, Ancona, Italy
| | - Donata Figaj
- Department of Biochemistry, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Leszek Kadzinski
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Urszula Zarzecka
- Department of Biochemistry, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Dorota Zurawa-Janicka
- Department of Biochemistry, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Bogdan Banecki
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Adam Lesner
- Department of Biochemistry, Faculty of Chemistry, University of Gdansk, Gdansk, Poland
| | - Fabio Tanfani
- Department of Life and Environmental Sciences, Universita Politecnica delle Marche, Ancona, Italy
| | - Barbara Lipinska
- Department of Biochemistry, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Joanna Skorko-Glonek
- Department of Biochemistry, Faculty of Biology, University of Gdansk, Gdansk, Poland
- * E-mail:
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Defensins and sepsis. BIOMED RESEARCH INTERNATIONAL 2014; 2014:180109. [PMID: 25210703 PMCID: PMC4151856 DOI: 10.1155/2014/180109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 05/08/2014] [Accepted: 06/16/2014] [Indexed: 01/12/2023]
Abstract
Sepsis is a leading cause of mortality and morbidity in the critical illness. Multiple immune inflammatory processes take part in the pathogenesis of sepsis. Defensins are endogenous antimicrobial peptides with three disulphide bonds created by six cysteine residues. Besides the intrinsic microbicidal properties, defensins are active players which modulate both innate and adaptive immunity against various infections. Defensins can recruit neutrophils, enhance phagocytosis, chemoattract T cells and dendritic cells, promote complement activation, and induce IL-1β production and pyrotosis. Previous publications have documented that defensins play important roles in a series of immune inflammatory diseases including sepsis. This review aims to briefly summarize in vitro, in vivo, and genetic studies on defensins' effects as well as corresponding mechanisms within sepsis and highlights their promising findings which may be potential targets in future therapies of sepsis.
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Silva PM, Gonçalves S, Santos NC. Defensins: antifungal lessons from eukaryotes. Front Microbiol 2014; 5:97. [PMID: 24688483 PMCID: PMC3960590 DOI: 10.3389/fmicb.2014.00097] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 02/21/2014] [Indexed: 01/07/2023] Open
Abstract
Over the last years, antimicrobial peptides (AMPs) have been the focus of intense research toward the finding of a viable alternative to current antifungal drugs. Defensins are one of the major families of AMPs and the most represented among all eukaryotic groups, providing an important first line of host defense against pathogenic microorganisms. Several of these cysteine-stabilized peptides present a relevant effect against fungi. Defensins are the AMPs with the broader distribution across all eukaryotic kingdoms, namely, Fungi, Plantae, and Animalia, and were recently shown to have an ancestor in a bacterial organism. As a part of the host defense, defensins act as an important vehicle of information between innate and adaptive immune system and have a role in immunomodulation. This multidimensionality represents a powerful host shield, hard for microorganisms to overcome using single approach resistance strategies. Pathogenic fungi resistance to conventional antimycotic drugs is becoming a major problem. Defensins, as other AMPs, have shown to be an effective alternative to the current antimycotic therapies, demonstrating potential as novel therapeutic agents or drug leads. In this review, we summarize the current knowledge on some eukaryotic defensins with antifungal action. An overview of the main targets in the fungal cell and the mechanism of action of these AMPs (namely, the selectivity for some fungal membrane components) are presented. Additionally, recent works on antifungal defensins structure, activity, and cytotoxicity are also reviewed.
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Affiliation(s)
- Patrícia M Silva
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisbon, Portugal
| | - Sónia Gonçalves
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisbon, Portugal
| | - Nuno C Santos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisbon, Portugal
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Antoni L, Nuding S, Weller D, Gersemann M, Ott G, Wehkamp J, Stange EF. Human colonic mucus is a reservoir for antimicrobial peptides. J Crohns Colitis 2013; 7:e652-64. [PMID: 23787054 DOI: 10.1016/j.crohns.2013.05.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 05/14/2013] [Accepted: 05/22/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND AIMS To prevent bacterial adherence and translocation, the colonic mucosa is covered by a protecting mucus layer and the epithelium synthesizes antimicrobial peptides. The present qualitative study investigated the contents and interaction of these peptides in and with rectal mucus. METHODS Rectal mucus extracts were analyzed for antimicrobial activity and screened with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, Dot blot and immunohistochemistry for antimicrobial peptides. In addition, binding of AMPs to mucins was investigated by Western blot and enzyme-linked lectin assays. RESULTS In functional tests the mucus layer exhibited a strong antimicrobial activity. We detected 11 antimicrobial peptides in mucus extracts from healthy persons including the defensins HBD-1 and -3, the cathelicidin LL-37, ubiquitin, lysozyme, histones, high mobility group nucleosome-binding domain-containing protein 2, ubiquicidin and other ribosomal proteins. AMPs were bound by mucins but this was demonstrated to be reversible and inhibition of antibacterial activity was limited. CONCLUSION These findings indicate that epithelial antimicrobial peptides are retained in the intestinal mucus layer without losing their efficacy. Thus, the mucus layer and its composition provide an attractive drug target to restore antimicrobial barrier function in intestinal diseases.
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Affiliation(s)
- Lena Antoni
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, University of Tübingen, Stuttgart, Germany
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Zhang Y, Cougnon FBL, Wanniarachchi YA, Hayden JA, Nolan EM. Reduction of human defensin 5 affords a high-affinity zinc-chelating peptide. ACS Chem Biol 2013; 8:1907-11. [PMID: 23841778 DOI: 10.1021/cb400340k] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Human defensin 5 (HD5) is a 32-residue cysteine-rich host-defense peptide that exhibits three disulfide bonds in the oxidized form (HD5ox). It is abundant in small intestinal Paneth cells, which release HD5 into the intestinal lumen and house a labile Zn(II) store of unknown function. Here, we consider the redox properties of HD5 and report that the reduced form, HD5red, is a metal-ion chelator. HD5 has a midpoint potential of -257 mV at pH 7.0. HD5red utilizes its cysteine residues to coordinate one equivalent of Zn(II) with an apparent Kd1 value in the midpicomolar range. Zn(II) or Cd(II) binding perturbs the oxidative folding pathway of HD5red to HD5ox. Whereas HD5red is highly susceptible to proteolytic degradation, the Zn(II)-bound form displays resistance to hydrolytic breakdown by trypsin and other proteases. The ability of a reduced defensin peptide to coordinate Zn(II) provides a putative mechanism for how these peptides persist in vivo.
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Affiliation(s)
- Yunfei Zhang
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139, United States
| | - Fabien B. L. Cougnon
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139, United States
| | - Yoshitha A. Wanniarachchi
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139, United States
| | - Joshua A. Hayden
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139, United States
| | - Elizabeth M. Nolan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139, United States
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36
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Antimicrobial activity of high-mobility-group box 2: a new function to a well-known protein. Antimicrob Agents Chemother 2013; 57:4782-93. [PMID: 23877675 DOI: 10.1128/aac.00805-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The human intestinal tract is highly colonized by a vast number of microorganisms. Despite this permanent challenge, infections remain rare, due to a very effective barrier defense system. Essential effectors of this system are antimicrobial peptides and proteins (AMPs), which are secreted by intestinal epithelial and lymphoid cells, balance the gut microbial community, and prevent the translocation of microorganisms. Several antimicrobial proteins have already been identified in the gut. Nonetheless, we hypothesized that additional AMPs are yet to be discovered in this setting. Using biological screening based on antimicrobial function, here we identified competent antibacterial activity of high-mobility-group box 2 (HMGB2) against Escherichia coli. By recombinant expression, we confirmed this biologically new antimicrobial activity against different commensal and pathogenic bacteria. In addition, we demonstrated that the two DNA-binding domains (HMG boxes A and B) are crucial for the antibiotic function. We detected HMGB2 in several gastrointestinal tissues by mRNA analysis and immunohistochemical staining. In addition to the nuclei, we also observed HMGB2 in the cytoplasm of intestinal epithelial cells. Furthermore, HMGB2 was detectable in vitro in the supernatants of two different cell types, supporting an extracellular function. HMGB2 expression was not changed in inflammatory bowel disease but was detected in certain stool samples of patients, whereas it was absent from control individuals. Taken together, we characterized HMGB2 as an antimicrobial protein in intestinal tissue, complementing the diverse repertoire of gut mucosal defense molecules.
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