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Schlievert PM, Kilgore SH, Beck LA, Yoshida T, Klingelhutz AJ, Leung DYM. Host Cationic Antimicrobial Molecules Inhibit S. aureus Exotoxin Production. mSphere 2023; 8:e0057622. [PMID: 36598227 PMCID: PMC9942567 DOI: 10.1128/msphere.00576-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 12/02/2022] [Indexed: 01/05/2023] Open
Abstract
Innate immune molecules, including antimicrobial peptides (for example, defensins) and lysozyme, function to delay or prevent bacterial infections. These molecules are commonly found on mucosal and skin surfaces. Staphylococcus aureus is a common pathogen and causes millions of infections annually. It is well known that innate immune molecules, such as defensins and lysozyme, either poorly inhibit or do not inhibit the growth of S. aureus. Our current studies show that the α-defensin human neutrophil α-defensin-1 (HNP-1) and lysozyme inhibit exotoxin production, both hemolysins and superantigens, which are required for S. aureus infection. HNP-1 inhibited exotoxin production at concentrations as low as 0.001 μg/mL. Lysozyme inhibited exotoxin production at 0.05 to 0.5 μg/mL. Both HNP-1 and lysozyme functioned through at least one two-component system (SrrA/B). The β-defensin human β-defensin 1 (HBD-1) inhibited hemolysin but not superantigen production. The cation chelator S100A8/A9 (calprotectin), compared to EDTA, was tested for the ability to inhibit exotoxin production. EDTA at high concentrations inhibited exotoxin production; these were the same concentrations that interfered with staphylococcal growth. S100A8/A9 at the highest concentration tested (10 μg/mL) had no effect on S. aureus growth but enhanced exotoxin production. Lower concentrations had no effect on growth or exotoxin production. Lysostaphin is regularly used to lyse S. aureus. The lytic concentrations of lysostaphin were the only concentrations that also inhibited growth and exotoxin production. Our studies demonstrate that a major activity of innate defensin peptides and lysozyme is inhibition of staphylococcal exotoxin production but not inhibition of growth. IMPORTANCE Staphylococcus aureus causes large numbers of both relatively benign and serious human infections, which are mediated in large part by the organisms' secreted exotoxins. Since 1921, it has been known that lysozyme and, as shown later in the 1900s, other innate immune peptides, including human neutrophil α-defensin-1 (HNP-1) and human β-defensin 1 (HBD-1), are either not antistaphylococcal or are only weakly inhibitory to growth. Our study confirms those findings but, importantly, shows that at subgrowth inhibitory concentrations, these positively charged innate immune peptides inhibit exotoxin production, including both hemolysins and the superantigen toxic shock syndrome toxin-1. The data show that the principal activity of innate immune peptides in the host is likely to be inhibition of exotoxin production required for staphylococcal mucosal or skin colonization rather than growth inhibition.
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Affiliation(s)
- Patrick M. Schlievert
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Samuel H. Kilgore
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Lisa A. Beck
- Department of Dermatology, University of Rochester Medical Center, Rochester, New York, USA
| | - Takeshi Yoshida
- Department of Dermatology, University of Rochester Medical Center, Rochester, New York, USA
| | - Aloysius J. Klingelhutz
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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Kling C, Pulliainen AT, Barth H, Ernst K. Human Peptides α-Defensin-1 and -5 Inhibit Pertussis Toxin. Toxins (Basel) 2021; 13:toxins13070480. [PMID: 34357952 PMCID: PMC8310310 DOI: 10.3390/toxins13070480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/01/2021] [Accepted: 07/09/2021] [Indexed: 01/13/2023] Open
Abstract
Bordetella pertussis causes the severe childhood disease whooping cough, by releasing several toxins, including pertussis toxin (PT) as a major virulence factor. PT is an AB5-type toxin, and consists of the enzymatic A-subunit PTS1 and five B-subunits, which facilitate binding to cells and transport of PTS1 into the cytosol. PTS1 ADP-ribosylates α-subunits of inhibitory G-proteins (Gαi) in the cytosol, which leads to disturbed cAMP signaling. Since PT is crucial for causing severe courses of disease, our aim is to identify new inhibitors against PT, to provide starting points for novel therapeutic approaches. Here, we investigated the effect of human antimicrobial peptides of the defensin family on PT. We demonstrated that PTS1 enzyme activity in vitro was inhibited by α-defensin-1 and -5, but not β-defensin-1. The amount of ADP-ribosylated Gαi was significantly reduced in PT-treated cells, in the presence of α-defensin-1 and -5. Moreover, both α-defensins decreased PT-mediated effects on cAMP signaling in the living cell-based interference in the Gαi-mediated signal transduction (iGIST) assay. Taken together, we identified the human peptides α-defensin-1 and -5 as inhibitors of PT activity, suggesting that these human peptides bear potential for developing novel therapeutic strategies against whooping cough.
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Affiliation(s)
- Carolin Kling
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (C.K.); (H.B.)
| | - Arto T. Pulliainen
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, FI-20520 Turku, Finland;
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (C.K.); (H.B.)
| | - Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany; (C.K.); (H.B.)
- Correspondence:
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Tian LM, Ke D. Acne Vulgaris is Associated with the Human β-Defensin 1-Gene Polymorphisms in Han Chinese Ethnic Group Patients. Clin Cosmet Investig Dermatol 2021; 14:123-128. [PMID: 33568929 PMCID: PMC7869712 DOI: 10.2147/ccid.s292797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/10/2021] [Indexed: 12/26/2022]
Abstract
Objective To study the relationship between the single nucleotide polymorphisms (SNPs) of the human β-defensin 1-gene (DEFB1) and the genetic susceptibility of acne vulgaris in the Han Chinese ethnic group. Methods A total of 104 patients with acne vulgaris and 126 healthy participants were included in our study. We analyzed the association between acne vulgaris and the polymorphisms in the DEFB1 G-52A, C-44G, and G-20A gene. We then analyzed the relationship between the different genotypes and the susceptibility to acne vulgaris. Results The frequency of DEFB1 C-44G genetic polymorphisms between the acne vulgaris group and the control group was significantly different (P < 0.05). The frequency of DEFB1 G-20A genetic polymorphisms between the acne vulgaris group and the control group was also significantly different (P < 0.05). Conclusion The −44G or −20A allele showed a low expression in acne vulgaris, which has already been shown to correlate with the low risk of acne vulgaris among Chinese Han patients. This further supports the contribution of the DEFB1 gene to the pathogenesis of acne.
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Affiliation(s)
- Li-Ming Tian
- Department of Dermatology, Wuhan No.1 Hospital, Hospital of Traditional Chinese and Western Medicine Affiliated to Hubei University of Chinese Medicine, Wuhan Hospital of Traditional Chinese and Western Medicine Affiliated to Huazhong University of Science and Technology, Wuhan, 430022, People's Republic of China
| | - Dan Ke
- Department of Dermatology, Chongqing Traditional Chinese Medicine Hospital, Chongqing, 400000, People's Republic of China
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Tan N, Hu S, Hu Z, Wu Z, Wang B. Quantitative proteomic characterization of microvesicles/exosomes from the cerebrospinal fluid of patients with acute bilirubin encephalopathy. Mol Med Rep 2020; 22:1257-1268. [PMID: 32468033 PMCID: PMC7339682 DOI: 10.3892/mmr.2020.11194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/06/2020] [Indexed: 01/10/2023] Open
Abstract
Severe hyperbilirubinemia causes neurotoxicity and may lead to acute bilirubin encephalopathy (ABE) during the critical period of central nervous system development. The aim of the present study was to identify differentially expressed proteins (DEPs) in microvesicles/exosomes (MV/E) isolated from the cerebrospinal fluid (CSF) of patients with ABE. Co-precipitation was used to isolate the MV/E from the CSF of patients with ABE and age-matched controls. Isobaric tagging for relative and absolute quantification-based proteomic technology combined with liquid chromatography/tandem mass spectrometry was used to identify DEPs in the MV/E. Bioinformatics analysis was subsequently performed to investigate Gene Ontology functional annotation and Kyoto Encyclopedia of Genes and Genomes enriched signaling pathways of these DEPs. A total of four proteins were selected for further validation via western blotting. A total of 291 dysregulated proteins were identified by comparing the patients with ABE with the controls. Bioinformatics analysis indicated the involvement of immune-inflammation-associated cellular processes and signaling pathways in the pathophysiology of ABE. In conclusion, the present study identified the proteomic profile of MV/E isolated from the CSF of patients with ABE. These results may provide an improved understanding of the pathogenesis of ABE and may help to identify early diagnostic biomarkers and therapeutic targets.
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Affiliation(s)
- Ning Tan
- Department of Pediatrics, Zhujiang Hospital, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong 510280, P.R. China
| | - Shuiwang Hu
- Guangdong Provincial Key Laboratory of Proteomics, Department of Pathophysiology, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Zhen Hu
- National and Local Joint Engineering Laboratory for High‑through Molecular Diagnosis Technology, Translational Medicine Institute, Collaborative Research Center for Post‑doctoral Mobile Stations of Central South University, Affiliated The First People's Hospital of Chenzhou, Southern Medical University, University of South China, Chenzhou, Hunan 423000, P.R. China
| | - Zhouli Wu
- Department of Neonatology, Affiliated The First People's Hospital of Chenzhou, Southern Medical University, University of South China, Chenzhou, Hunan 423000, P.R. China
| | - Bin Wang
- Department of Pediatrics, Zhujiang Hospital, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong 510280, P.R. China
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Sasani N, Roghanian R, Emtiazi G, Aghaie A. A Novel Approach on Leukodepletion Filters: Investigation of Synergistic Anticancer Effect of Purified α-Defensins and Nisin. Adv Pharm Bull 2020; 11:378-384. [PMID: 33880361 PMCID: PMC8046393 DOI: 10.34172/apb.2021.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 12/09/2019] [Accepted: 04/15/2020] [Indexed: 12/22/2022] Open
Abstract
Purpose: There are number of reports available regarding defensins activity against mammalian cells besides their antimicrobial and immune regulatory activities. This study aims to investigate anticancer and apoptosis activity of the purified defensins from leukodepletion filters alone or in synergism with bacterial peptide, nisin, on prostate and colorectal cancer. Methods: Leucoflex LCR-5 filters were backflushed by an optimized elution system. Isolated granulocytes were sonicated and the supernatant treated before further purification by high performance liquid chromatography (HPLC). SDS-PAGE and western blot testing verified the fraction. Cell culture on PC-3 (human prostate adenocarcinoma), and HCT-116 (human colorectal carcinoma) were conducted following by MTT assays in addition to annexin flow cytometry for sole and synergistic effects with peptide nisin. Results: Viable and active neutrophils could recover, and α-defensins were extracted and purified. Combinations of an optimal dose of α-defensins and nisin showed a remarkable synergistic effect on cancer cell lines (over 90% and 70% for PC-3 and HCT-116, respectively). Conclusion: It also observed that less than 40% of both cells could survive after co-treatment with optimal dose. Also, apoptosis was increased after treatment by these peptides together. Annexin Vpositive populations significantly increased in percentage in comparison with control.
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Affiliation(s)
- Niloofar Sasani
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, P. O Box 81746-79441, Isfahan, Iran
| | - Rasoul Roghanian
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, P. O Box 81746-79441, Isfahan, Iran
| | - Giti Emtiazi
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, P. O Box 81746-79441, Isfahan, Iran
| | - Afsaneh Aghaie
- Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
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Fischer S, Ückert AK, Landenberger M, Papatheodorou P, Hoffmann-Richter C, Mittler AK, Ziener U, Hägele M, Schwan C, Müller M, Kleger A, Benz R, Popoff MR, Aktories K, Barth H. Human peptide α-defensin-1 interferes with Clostridioides difficile toxins TcdA, TcdB, and CDT. FASEB J 2020; 34:6244-6261. [PMID: 32190927 DOI: 10.1096/fj.201902816r] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/23/2019] [Accepted: 02/27/2020] [Indexed: 12/15/2022]
Abstract
The human pathogenic bacterium Clostridioides difficile produces two exotoxins TcdA and TcdB, which inactivate Rho GTPases thereby causing C. difficile-associated diseases (CDAD) including life-threatening pseudomembranous colitis. Hypervirulent strains produce additionally the binary actin ADP-ribosylating toxin CDT. These strains are hallmarked by more severe forms of CDAD and increased frequency and severity. Once in the cytosol, the toxins act as enzymes resulting in the typical clinical symptoms. Therefore, targeting and inactivation of the released toxins are of peculiar interest. Prompted by earlier findings that human α-defensin-1 neutralizes TcdB, we investigated the effects of the defensin on all three C. difficile toxins. Inhibition of TcdA, TcdB, and CDT was demonstrated by analyzing toxin-induced changes in cell morphology, substrate modification, and decrease in transepithelial electrical resistance. Application of α-defensin-1 protected cells and human intestinal organoids from the cytotoxic effects of TcdA, TcdB, CDT, and their combination which is attributed to a direct interaction between the toxins and α-defensin-1. In mice, the application of α-defensin-1 reduced the TcdA-induced damage of intestinal loops in vivo. In conclusion, human α-defensin-1 is a specific and potent inhibitor of the C. difficile toxins and a promising agent to develop novel therapeutic options against C. difficile infections.
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Affiliation(s)
- Stephan Fischer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Anna-Katharina Ückert
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Marc Landenberger
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | | | | | - Ann-Katrin Mittler
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Ulrich Ziener
- Institute of Organic Chemistry III, Ulm University, Ulm, Germany
| | - Marlen Hägele
- Department of Internal Medicine I, University of Ulm Medical Center, Ulm, Germany
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Martin Müller
- Department of Internal Medicine I, University of Ulm Medical Center, Ulm, Germany
| | - Alexander Kleger
- Department of Internal Medicine I, University of Ulm Medical Center, Ulm, Germany
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Michel R Popoff
- Department of Anaerobic Bacteria, Pasteur Institute, Paris, France
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
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Sher Khan R, Iqbal A, Malak R, Shehryar K, Attia S, Ahmed T, Ali Khan M, Arif M, Mii M. Plant defensins: types, mechanism of action and prospects of genetic engineering for enhanced disease resistance in plants. 3 Biotech 2019; 9:192. [PMID: 31065492 PMCID: PMC6488698 DOI: 10.1007/s13205-019-1725-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 04/19/2019] [Indexed: 10/26/2022] Open
Abstract
Natural antimicrobial peptides have been shown as one of the important tools to combat certain pathogens and play important role as a part of innate immune system in plants and, also adaptive immunity in animals. Defensin is one of the antimicrobial peptides with a diverse nature of mechanism against different pathogens like viruses, bacteria and fungi. They have a broad function in humans, vertebrates, invertebrates, insects, and plants. Plant defensins primarily interact with membrane lipids for their biological activity. Several antimicrobial peptides (AMPs) have been overexpressed in plants for enhanced disease protection. The plants defensin peptides have been efficiently employed as an effective strategy for control of diseases in plants. They can be successfully integrated in plants genome along with some other peptide genes in order to produce transgenic crops for enhanced disease resistance. This review summarizes plant defensins, their expression in plants and enhanced disease resistance potential against phytopathogens.
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Affiliation(s)
- Raham Sher Khan
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Aneela Iqbal
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Radia Malak
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Kashmala Shehryar
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Syeda Attia
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Talaat Ahmed
- Department of Biological and Environmental Sciences, College of Arts and Science, Qatar University, Doha, Qatar
| | - Mubarak Ali Khan
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Muhammad Arif
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Masahiro Mii
- Center for Environment, Health and Field Sciences, Chiba University Japan, Chiba, Japan
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Fischer S, Popoff MR, Barth H. Human alpha-defensin-1 protects cells from intoxication with Clostridium perfringens iota toxin. Pathog Dis 2018; 76:4931056. [PMID: 29635426 DOI: 10.1093/femspd/fty022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/06/2018] [Indexed: 02/06/2023] Open
Abstract
Iota toxin is produced by Clostridium perfringens type E strains and associated with diarrhea in cattle and lambs. This binary protein toxin comprises the enzyme component iota a (Ia), which ADP-ribosylates G-actin, and the separate transport component iota b (Ib), which delivers Ia into the cytosol of target cells. Ib binds to cell receptors and forms biologically active toxin complexes with Ia, which cause rounding of adherent cells due to the destruction of the actin cytoskeleton. Here, we report that the human peptide α-defensin-1 protects cultured cells including human colon cells from intoxication with iota toxin. In contrast, the related ß-defensin-1 had no effect, indicating a specific mode of action. The α-defensin-1 did not inhibit ADP-ribosylation of actin by Ia in vitro. Pretreatment of Ib with α-defensin-1 prior to addition of Ia prevented intoxication. Additionally, α-defensin-1 protected cells from cytotoxic effects mediated by Ib in the absence of Ia, implicating that α-defensin-1 interacts with Ib to prevent the formation of biologically active iota toxin on cells. In conclusion, the findings contribute to a better understanding of the functions of α-defensin-1 and suggest that this human peptide might be an attractive starting point to develop novel pharmacological options to treat/prevent diseases associated with iota toxin-producing Clostridium perfringens strains.
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Affiliation(s)
- Stephan Fischer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89081 Ulm, Germany
| | - Michel R Popoff
- Department of Anaerobic Bacteria, Pasteur Institute, 75015 Paris, France
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, 89081 Ulm, Germany
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Subramanian K, Bergman P, Henriques-Normark B. Vitamin D Promotes Pneumococcal Killing and Modulates Inflammatory Responses in Primary Human Neutrophils. J Innate Immun 2017; 9:375-386. [PMID: 28241127 DOI: 10.1159/000455969] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 01/10/2017] [Indexed: 11/19/2022] Open
Abstract
Streptococcus pneumoniae is a major human pathogen and a leading cause of pneumonia, septicemia, and meningitis worldwide. Despite clinical studies linking vitamin D deficiency and pneumonia, molecular mechanisms behind these observations remain unclear. In particular, the effects of vitamin D on neutrophil responses remain unknown. Using pneumococcal strains, primary neutrophils isolated from human blood, and sera from patients with frequent respiratory tract infections (RTIs), we investigated the effects of vitamin D on neutrophil bactericidal and inflammatory responses, including pattern recognition receptors, antimicrobial peptides, and cytokine regulation. We found that vitamin D upregulated pattern recognition receptors, TLR2, and NOD2, and induced the antimicrobial human neutrophil peptides (HNP1-3) and LL-37, resulting in increased killing of pneumococci in a vitamin D receptor-dependent manner. Antibodies targeting HNP1-3 inhibited bacterial killing. Vitamin D supplementation of serum from patients with bacterial RTIs enhanced neutrophil killing. Moreover, vitamin D lowered inflammatory cytokine production by infected neutrophils via IL-4 production and the induction of suppressor of cytokine signaling (SOCS) proteins SOCS-1 and SOCS-3, leading to the suppression of NF-κB signaling. Thus, vitamin D enhances neutrophil killing of S. pneumoniae while dampening excessive inflammatory responses and apoptosis, suggesting that vitamin D could be used alongside antibiotics when treating pneumococcal infections.
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Affiliation(s)
- Karthik Subramanian
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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Xie S, Spelmink L, Codemo M, Subramanian K, Pütsep K, Henriques-Normark B, Olliver M. Cinobufagin Modulates Human Innate Immune Responses and Triggers Antibacterial Activity. PLoS One 2016; 11:e0160734. [PMID: 27529866 PMCID: PMC4986986 DOI: 10.1371/journal.pone.0160734] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/25/2016] [Indexed: 02/06/2023] Open
Abstract
The traditional Chinese medicine Chan-Su is widely used for treatment of cancer and cardiovascular diseases, but also as a remedy for infections such as furunculosis, tonsillitis and acute pharyngitis. The clinical use of Chan-Su suggests that it has anti-infective effects, however, the mechanism of action is incompletely understood. In particular, the effect on the human immune system is poorly defined. Here, we describe previously unrecognized immunomodulatory activities of cinobufagin (CBG), a major bioactive component of Chan-Su. Using human monocyte-derived dendritic cells (DCs), we show that LPS-induced maturation and production of a number of cytokines was potently inhibited by CBG, which also had a pro-apoptotic effect, associated with activation of caspase-3. Interestingly, CBG triggered caspase-1 activation and significantly enhanced IL-1β production in LPS-stimulated cells. Finally, we demonstrate that CBG upregulates gene expression of the antimicrobial peptides (AMPs) hBD-2 and hBD-3 in DCs, and induces secretion of HNP1-3 and hCAP-18/LL-37 from neutrophils, potentiating neutrophil antibacterial activity. Taken together, our data indicate that CBG modulates the inflammatory phenotype of DCs in response to LPS, and triggers an antibacterial innate immune response, thus proposing possible mechanisms for the clinical effects of Chan-Su in anti-infective therapy.
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Affiliation(s)
- Shanshan Xie
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin, China
| | - Laura Spelmink
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Mario Codemo
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Karthik Subramanian
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Katrin Pütsep
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
- Department of Clinical Microbiology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Marie Olliver
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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Elevated Concentration of Defensins in Hepatitis C Virus-Infected Patients. J Immunol Res 2016; 2016:8373819. [PMID: 27413763 PMCID: PMC4931052 DOI: 10.1155/2016/8373819] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 04/17/2016] [Accepted: 04/27/2016] [Indexed: 12/23/2022] Open
Abstract
Hepatitis C virus (HCV) is the major etiological agent of human non-A and non-B hepatitis, affecting around 180 million people worldwide. Defensins, small cysteine-rich cationic peptides, are shown to have potent antibacterial, antiviral, and antifungal properties. Defensins can be found in both normal and microbial infected patients, at variable concentrations. Notably, viral infections are often associated with elevated concentrations of defensins. The current study aimed to estimate the concentrations of total, α-, and β-defensins in serum taken from normal and HCV-infected patients. 12 healthy (noninfected) and 34 HCV-infected patients were enrolled. Standardized immunoassay kits were used to obtain serum concentrations of defensins. The obtained results were calibrated against kit standard reagents. Total defensin concentrations in HCV-infected patients were significantly higher (2- to 105-fold) compared to healthy individuals. The concentrations of α-defensins were also significantly elevated in the HCV-infected patients (31–1398 ng/50 μL). However, concentrations of β-defensins ranged from 44.5 ng/50 μL to 1056 ng/50 μL. The results did not reveal differences in serum defensin concentration between male and female HCV-infected patients. A-defensin concentration of ≥250 ng/50 μL was found to contain more β-defensins than total defensins and α-defensins. This study concludes, for the first time, that serum defensin levels are elevated in HCV-infected patients.
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12
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Antimicrobial potentials and structural disorder of human and animal defensins. Cytokine Growth Factor Rev 2016; 28:95-111. [DOI: 10.1016/j.cytogfr.2015.11.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/24/2015] [Accepted: 11/03/2015] [Indexed: 02/07/2023]
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13
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Lu W, de Leeuw E. Functional intersection of Human Defensin 5 with the TNF receptor pathway. FEBS Lett 2014; 588:1906-12. [PMID: 24681099 DOI: 10.1016/j.febslet.2014.03.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 03/06/2014] [Accepted: 03/14/2014] [Indexed: 12/21/2022]
Abstract
Defensins are cationic antimicrobial peptides that contribute to regulation of host cell function also. Here, we report on the regulation of cell death by Human Defensin 5, the major antimicrobial peptide of ileal Paneth cells. We find that Human Defensin 5-mediated cellular effects depend on functional expression of Tumor Necrosis Factor receptors and downstream mediators of TNF signaling. Our data indicate the involvement of interactions between Human Defensin 5 and the extra-cellular domain of Tumor Necrosis Factor receptor 1. Human Defensin-5 also induces apoptosis intrinsically by targeting the mitochondrial membrane.
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Affiliation(s)
- Wuyuan Lu
- Institute of Human Virology, University of Maryland Baltimore School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Erik de Leeuw
- Institute of Human Virology, University of Maryland Baltimore School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
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Lehrer RI, Cole AM, Selsted ME. θ-Defensins: cyclic peptides with endless potential. J Biol Chem 2012; 287:27014-9. [PMID: 22700960 DOI: 10.1074/jbc.r112.346098] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
θ-Defensins, the only cyclic peptides of animal origin, have been isolated from the leukocytes of rhesus macaques and baboons. Their biogenesis is unusual because each peptide is an 18-residue chimera formed by the head-to-tail splicing of nonapeptides derived from two separate precursors. θ-Defensins have multiple arginines and a ladder-like tridisulfide array spanning their two antiparallel β-strands. Human θ-defensin genes contain a premature stop codon that prevents effective translation of the needed precursors; consequently, these peptides are not present in human leukocytes. Synthetic θ-defensins with sequences that correspond to those encoded within the human pseudogenes are called retrocyclins. Retrocyclin-1 inhibits the cellular entry of HIV-1, HSV, and influenza A virus. The rhesus θ-defensin RTD-1 protects mice from an experimental severe acute respiratory syndrome coronavirus infection, and retrocyclin-1 protects mice from infection by Bacillus anthracis spores. The small size, unique structure, and multiple host defense activities of θ-defensins make them intriguing potential therapeutic agents.
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Affiliation(s)
- Robert I Lehrer
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1688, USA.
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15
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Fu LB, Yu JL, Liu WH. [Biological characteristics of defensin and its disease-resistance genetic engineering]. YI CHUAN = HEREDITAS 2011; 33:512-519. [PMID: 21586398 DOI: 10.3724/sp.j.1005.2011.00512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Defensin is a kind of cysteine-rich small peptide, which has a broad spectrum of resistance to bacteria with a special resistance mechanism. So far, a large number of studies on defensins have been reported, and the different types of defensins have been isolated from various organisms. A broad prospect of application on defensins has been displayed both in genetic engineering and medicine field. This article reviewed the classification and the biological characteristics of defensins, including mammalian α-, β-, θ-defensins, insect defensins, and plant defensins. The molecular structures, antibacterial activities, and antibacterial mechanisms of these definsins were summarized. The two mechanisms of de-fensin, including independent membrane mechanism and targeting of intracellular compounds by defensins, are ex-pounded. This paper also summarized the researches on isolation and expression of defensin genes and disease resistance genetic engineering of mammal and plant defensins. A prospect of the future applications of defensin both in biophar-maceutical sciences and plant disease resistance genetic engineering was discussed.
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Affiliation(s)
- Lan-Bao Fu
- 1. The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing 100193, China.
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16
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Human alpha-defensins inhibit hemolysis mediated by cholesterol-dependent cytolysins. Infect Immun 2009; 77:4028-40. [PMID: 19581399 DOI: 10.1128/iai.00232-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Many pathogenic gram-positive bacteria release exotoxins that belong to the family of cholesterol-dependent cytolysins. Here, we report that human alpha-defensins HNP-1 to HNP-3 acted in a concentration-dependent manner to protect human red blood cells from the lytic effects of three of these exotoxins: anthrolysin O (ALO), listeriolysin O, and pneumolysin. HD-5 was very effective against listeriolysin O but less effective against the other toxins. Human alpha-defensins HNP-4 and HD-6 and human beta-defensin-1, -2, and -3 lacked protective ability. HNP-1 required intact disulfide bonds to prevent toxin-mediated hemolysis. A fully linearized analog, in which all six cysteines were replaced by aminobutyric acid (Abu) residues, showed greatly reduced binding and protection. A partially unfolded HNP-1 analog, in which only cysteines 9 and 29 were replaced by Abu residues, showed intact ALO binding but was 10-fold less potent in preventing hemolysis. Surface plasmon resonance assays revealed that HNP-1 to HNP-3 bound all three toxins at multiple sites and also that solution-phase HNP molecules could bind immobilized HNP molecules. Defensin concentrations that inhibited hemolysis by ALO and listeriolysin did not prevent these toxins from binding either to red blood cells or to cholesterol. Others have shown that HNP-1 to HNP-3 inhibit lethal toxin of Bacillus anthracis, toxin B of Clostridium difficile, diphtheria toxin, and exotoxin A of Pseudomonas aeruginosa; however, this is the first time these defensins have been shown to inhibit pore-forming toxins. An "ABCDE mechanism" that can account for the ability of HNP-1 to HNP-3 to inhibit so many different exotoxins is proposed.
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Abstract
A new, hypervirulent strain of Clostridium difficile, called NAP1/BI/027, has been implicated in C. difficile outbreaks associated with increased morbidity and mortality since the early 2000s. The epidemic strain is resistant to fluoroquinolones in vitro, which was infrequent prior to 2001. The name of this strain reflects its characteristics, demonstrated by different typing methods: pulsed-field gel electrophoresis (NAP1), restriction endonuclease analysis (BI) and polymerase chain reaction (027). In 2004 and 2005, the US Centers for Disease Control and Prevention (CDC) emphasized that the risk of C. difficile-associated diarrhea (CDAD) is increased, not only by the usual factors, including antibiotic exposure, but also gastrointestinal surgery/manipulation, prolonged length of stay in a healthcare setting, serious underlying illness, immune-compromising conditions, and aging. Patients on proton pump inhibitors (PPIs) have an elevated risk, as do peripartum women and heart transplant recipients. Before 2002, toxic megacolon in C. difficile-associated colitis (CDAC), was rare, but its incidence has increased dramatically. Up to two-thirds of hospitalized patients may be infected with C. difficile. Asymptomatic carriers admitted to healthcare facilities can transmit the organism to other susceptible patients, thereby becoming vectors. Fulminant colitis is reported more frequently during outbreaks of C. difficile infection in patients with inflammatory bowel disease (IBD). C. difficile infection with IBD carries a higher mortality than without underlying IBD. This article reviews the latest information on C. difficile infection, including presentation, vulnerable hosts and choice of antibiotics, alternative therapies, and probiotics and immunotherapy. We review contact precautions for patients with known or suspected C. difficile-associated disease. Healthcare institutions require accurate and rapid diagnosis for early detection of possible outbreaks, to initiate specific therapy and implement effective control measures. A comprehensive C. difficile infection control management rapid response team (RRT) is recommended for each health care facility. A communication network between RRTs is recommended, in coordination with each country’s department of health. Our aim is to convey a comprehensive source of information and to guide healthcare professionals in the difficult decisions that they face when caring for these oftentimes very ill patients.
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Droin N, Hendra JB, Ducoroy P, Solary E. Human defensins as cancer biomarkers and antitumour molecules. J Proteomics 2009; 72:918-27. [PMID: 19186224 DOI: 10.1016/j.jprot.2009.01.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 01/06/2009] [Accepted: 01/07/2009] [Indexed: 12/20/2022]
Abstract
Human defensins, which are small cationic peptides produced by neutrophils and epithelial cells, form two genetically distinct alpha and beta subfamilies. They are involved in innate immunity through killing microbial pathogens or neutralizing bacterial toxins and in adaptive immunity by serving as chemoattractants and activators of immune cells. alpha-defensins are mainly packaged in neutrophil granules (HNP1, HNP2, HNP3) or secreted by intestinal Paneth cells (HD5, HD6), while beta-defensins are expressed in mucosa and epithelial cells. Using surface enhanced laser desorption/ionisation time-of-flight (SELDI-TOF) mass spectrometry (MS), alpha-defensins were found to be expressed in a variety of human tumours, either in tumour cells or at their surface. HNP1-3 peptides are also secreted and their accumulation in biological fluids was proposed as a tumour biomarker. Conversely, beta-defensin-1 (HBD-1) is down-regulated in some tumour types in which it could behave as a tumour suppressor protein. Alpha-defensins promote tumour cell growth or, at higher concentration, provoke cell death. These peptides also inhibit angiogenesis, which, in addition to immunomodulation, indicates a complex role in tumour development. This review summarizes current knowledge of defensins to discuss their role in tumour growth, tumour monitoring and cancer treatment.
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19
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Abstract
Emberben az antimikrobiális peptidek három fő csoportját a defensinek, a cathelicidinek és a histatinok képezik. Ezek biokémiai sajátságaikban és antimikrobiális hatásuk spektruma tekintetében igen különbözőek, de valamennyi hasznosan szolgálja a szervezet mikrobiális fertőzésekkel szembeni védelmét. Ezeket a peptideket jó ideig csupán új típusú antimikrobiális ágenseknek tekintették, újabb tanulmányok során azonban feltárták, hogy antimikrobiális aktivitásuk mellett sok más – ugyancsak a gazdavédelmet szolgáló – biológiai aktivitással rendelkeznek. A veleszületett immunitás fontos komponenseinek bizonyultak, továbbá azt is kimutatták róluk, hogy az éretlen dendritikus sejteken és lymphocytákon lévő különböző receptorokkal való kölcsönhatás révén tulajdonképpen ezek a peptidek indítják be az adaptív immunválasz-reakciókat is, amelyekben aztán további immunmodulátori szerepet játszanak. Az LL-37-tel kapcsolatban pedig egyenesen azt állítják, hogy annak immunmoduláló aktivitása erősebb az antimikrobiális aktivitásnál. A humán α-defensinekről pedig azt is kimutatták, hogy más fajban is megőrzik aktivitásukat, egerekben ugyanis immunadjuváns hatást fejtettek ki. Újabban egyre több közleményben arról számolnak be, hogy számos emberi betegséggel társultan e gazdavédő kis peptidek termelődésének károsodása és/vagy funkcióinak zavarai figyelhetők meg. E peptidek multifunkcionális szerepének felismerése pedig a gyógyszeripar irántuk való fokozott érdeklődését eredményezte.
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Affiliation(s)
- Károly Lapis
- 1 Semmelweis Egyetem, Általános Orvostudományi Kar I. Patológia és Kísérleti Rákkutató Intézet Budapest Üllői út 26. 1085
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Dawson RM, Liu CQ. Properties and applications of antimicrobial peptides in biodefense against biological warfare threat agents. Crit Rev Microbiol 2008; 34:89-107. [PMID: 18568863 DOI: 10.1080/10408410802143808] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent advances in knowledge of the properties of antimicrobial peptides (AMPs) are reviewed. AMPs are typically small, positively charged, amphipathic peptides that interact electrostatically and non-stereospecifically with the bacterial cell membrane, resulting in its permeabilization and cell death. Classes of AMPs, their mechanisms of action, hemolytic activity, and cytotoxicity towards host cells are discussed. A particular focus is AMPs with potential for use in defense against biological warfare agents. Some AMPs cytotoxic to Bacillus anthracis have been described. Synthesis of these peptides in multivalent form leads to a synergistic increase in antibacterial activity. Strategies to enhance the potency, stability, and selectivity of AMPs are discussed.
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Hudson MJ, Beyer W, Böhm R, Fasanella A, Garofolo G, Golinski R, Goossens PL, Hahn U, Hallis B, King A, Mock M, Montecucco C, Ozin A, Tonello F, Kaufmann SH. Bacillus anthracis: balancing innocent research with dual-use potential. Int J Med Microbiol 2008; 298:345-64. [PMID: 18375178 PMCID: PMC7106442 DOI: 10.1016/j.ijmm.2007.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 09/21/2007] [Accepted: 09/28/2007] [Indexed: 12/30/2022] Open
Abstract
Anthrax Euronet, a Coordination Action of the EU 6th Framework Programme, was designed to strengthen networking activities between anthrax research groups in Europe and to harmonise protocols for testing anthrax vaccines and therapeutics. Inevitably, the project also addressed aspects of the current political issues of biosecurity and dual-use research, i.e. research into agents of important diseases of man, livestock or agriculture that could be used as agents of bioterrorism. This review provides a comprehensive overview of the biology of Bacillus anthracis, of the pathogenesis, epidemiology and diagnosis of anthrax, as well as vaccine and therapeutic intervention strategies. The proposed requirement for a code of conduct for working with dual-use agents such as the anthrax bacillus is also discussed.
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Affiliation(s)
| | | | | | - Antonio Fasanella
- Istituto Zooprofilattico Sperimentale of Puglia and Basilicata, Foggia, Italy
| | - Giuliano Garofolo
- Istituto Zooprofilattico Sperimentale of Puglia and Basilicata, Foggia, Italy
| | - Robert Golinski
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, D-10117 Berlin, Germany
| | | | | | - Bassam Hallis
- Health Protection Agency, Porton Down, Salisbury, UK
| | | | | | | | - Amanda Ozin
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, D-10117 Berlin, Germany
| | | | - Stefan H.E. Kaufmann
- Department of Immunology, Max Planck Institute for Infection Biology, Charitéplatz 1, D-10117 Berlin, Germany
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Giesemann T, Guttenberg G, Aktories K. Human alpha-defensins inhibit Clostridium difficile toxin B. Gastroenterology 2008; 134:2049-58. [PMID: 18435932 DOI: 10.1053/j.gastro.2008.03.008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 02/27/2008] [Accepted: 03/06/2008] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS Clostridium difficile toxins A and B are major virulence factors implicated in pseudomembranous colitis and antibiotic-associated diarrhea. The toxins are glucosyltransferases, which inactivate Rho proteins involved in cellular signaling. Human alpha-defensins as part of the innate immune system inactivate various microbial pathogens as well as specific bacterial exotoxins. Here, we studied the effects of alpha-defensins human neutrophil protein (HNP)-1, HNP-3, and enteric human defensin (HD)-5 on the activity of C difficile toxins A and B. METHODS Inactivation of C difficile toxins by alpha-defensins in vivo was monitored by microscopy, determination of the transepithelial resistance of CaCo-2 cell monolayers, and analysis of the glucosylation of Rac1 in toxin-treated cells. In vitro glucosylation was used to determine K(m) and median inhibitory concentration (IC(50)) values. Formation of defensin-toxin complexes was analyzed by precipitation and turbidity studies. RESULTS Treatment of cells with human alpha-defensins caused loss of cytotoxicity of toxin B, but not of toxin A. Only alpha-defensins, but not beta-defensin-1 or cathelicidin LL-37, inhibited toxin B-catalyzed in vitro glucosylation of Rho guanosine triphosphatases in a competitive manner, increasing K(m) values for uridine 5'-diphosphate-glucose up to 10-fold. The IC(50) values for inhibition of toxin B-catalyzed glucosylation by the alpha-defensins were 0.6-1.5 micromol/L. At high concentrations, defensins (HNP-1 > or = 2 micromol/L) caused high-molecular-mass aggregates, comparable to Bacillus anthracis protective antigen and lethal factor. CONCLUSION Our data indicate that toxin B interacts with high affinity with alpha-defensins and suggest that defensins may provide a defense mechanism against some types of clostridial glucosylating cytotoxins.
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Affiliation(s)
- Torsten Giesemann
- Institut für Experimentelle and Klinische Pharmakologie und Toxikologie, Universität Freiburg, Freiburg, Germany
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24
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Kaufmann SHE. The contribution of immunology to the rational design of novel antibacterial vaccines. Nat Rev Microbiol 2007; 5:491-504. [PMID: 17558425 DOI: 10.1038/nrmicro1688] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In most cases, a successful vaccine must induce an immune response that is better than the response invoked by natural infection. Vaccines are still unavailable for several bacterial infections and vaccines to prevent such infections will be best developed on the basis of our increasing insights into the immune response. Knowledge of the signals that determine the best possible acquired immune response against a given pathogen - comprising a profound T- and B-cell memory response as well as long-lived plasma cells - will provide the scientific framework for the rational design of novel antibacterial vaccines.
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Affiliation(s)
- Stefan H E Kaufmann
- Max Planck Institute for Infection Biology, Department of Immunology, Charitéplatz 1, D-10117 Berlin, Germany.
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25
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King MR, Steenbergen SM, Vimr ER. Going for baroque at the Escherichia coli K1 cell surface. Trends Microbiol 2007; 15:196-202. [PMID: 17418577 DOI: 10.1016/j.tim.2007.03.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 03/01/2007] [Accepted: 03/22/2007] [Indexed: 01/23/2023]
Abstract
Phase variation is usually thought of as the stochastic switching between alternatively expressed ('on') and unexpressed ('off') phenotypic states. However, coupling synthesis of a monotonous homopolysaccharide to a mechanism of random but incomplete chemical modification produces almost infinite structural variation. Potentially limitless variability implies that evolution can produce highly ornate or extravagant flourishes reminiscent of the baroque style. Here, we describe an analysis of capsular polysialic acid form variation in Escherichia coli K1, demonstrating that the large number of variant structures is controlled by a single contingency locus. The mechanism for generating maximum structural diversity from maximal genetic parsimony is conferred by a simple translational switch carried on a K1-specific prophage.
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Affiliation(s)
- Michael R King
- Laboratory of Sialobiology, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
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Ceraul SM, Dreher-Lesnick SM, Gillespie JJ, Rahman MS, Azad AF. New tick defensin isoform and antimicrobial gene expression in response to Rickettsia montanensis challenge. Infect Immun 2007; 75:1973-83. [PMID: 17261604 PMCID: PMC1865714 DOI: 10.1128/iai.01815-06] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies aimed at elucidating the rickettsia-tick interaction have discovered that the spotted fever group rickettsia Rickettsia montanensis, a relative of R. rickettsii, the etiologic agent of Rocky Mountain spotted fever, induces differential gene expression patterns in the ovaries of the hard tick Dermacentor variabilis. Here we describe a new defensin isoform, defensin-2, and the expression patterns of genes for three antimicrobials, defensin-1 (vsnA1), defensin-2, and lysozyme, in the midguts and fat bodies of D. variabilis ticks that were challenged with R. montanensis. Bioinformatic and phylogenetic analyses of the primary structure of defensin-2 support its role as an antimicrobial. The tissue distributions of the three antimicrobials, especially the two D. variabilis defensin isoforms, are markedly different, illustrating the immunocompetence of the many tissues that R. montanensis presumably invades once acquired by the tick. Antimicrobial gene expression patterns in R. montanensis-challenged ticks suggest that antimicrobial genes play a role during the acquisition-invasion stages in the tick.
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Affiliation(s)
- Shane M Ceraul
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 660 West Redwood St., HH Room 324, Baltimore, MD 21201, USA.
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