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Huang J, Kang W, Yi D, Zhu S, Xiang Y, Liu C, Li H, Dai D, Su J, He J, Liang Z. Intranasal B5 promotes mucosal defence against Actinobacillus pleuropneumoniae via ameliorating early immunosuppression. Virulence 2024; 15:2316459. [PMID: 38378464 PMCID: PMC10880497 DOI: 10.1080/21505594.2024.2316459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 02/04/2024] [Indexed: 02/22/2024] Open
Abstract
Actinobacillus pleuropneumoniae (APP) is an important pathogen of the porcine respiratory disease complex, which leads to huge economic losses worldwide. We previously demonstrated that Pichia pastoris-producing bovine neutrophil β-defensin-5 (B5) could resist the infection by the bovine intracellular pathogen Mycobacterium bovis. In this study, the roles of synthetic B5 in regulating mucosal innate immune response and protecting against extracellular APP infection were further investigated using a mouse model. Results showed that B5 promoted the production of tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and interferon (IFN)-β in macrophages as well as dendritic cells (DC) and enhanced DC maturation in vitro. Importantly, intranasal B5 was safe and conferred effective protection against APP via reducing the bacterial load in lungs and alleviating pulmonary inflammatory damage. Furthermore, in the early stage of APP infection, we found that intranasal B5 up-regulated the secretion of TNF-α, IL-1β, IL-17, and IL-22; enhanced the rapid recruitment of macrophages, neutrophils, and DC; and facilitated the generation of group 3 innate lymphoid cells in lungs. In addition, B5 activated signalling pathways associated with cellular response to IFN-β and activation of innate immune response in APP-challenged lungs. Collectively, B5 via the intranasal route can effectively ameliorate the immune suppression caused by early APP infection and provide protection against APP. The immunization strategy may be applied to animals or human respiratory bacterial infectious diseases. Our findings highlight the potential importance of B5, enhancing mucosal defence against intracellular bacteria like APP which causes early-phase immune suppression.
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Affiliation(s)
- Jingsheng Huang
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Weichao Kang
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Dandan Yi
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Shuxin Zhu
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Yifei Xiang
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Chengzhi Liu
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Han Li
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Dejia Dai
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Jieyu Su
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Jiakang He
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Zhengmin Liang
- College of Animal Science and Technology, Guangxi University, Nanning, China
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2
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Hemmati S, Saeidikia Z, Seradj H, Mohagheghzadeh A. Immunomodulatory Peptides as Vaccine Adjuvants and Antimicrobial Agents. Pharmaceuticals (Basel) 2024; 17:201. [PMID: 38399416 PMCID: PMC10892805 DOI: 10.3390/ph17020201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/25/2024] Open
Abstract
The underdevelopment of adjuvant discovery and diversity, compared to core vaccine technology, is evident. On the other hand, antibiotic resistance is on the list of the top ten threats to global health. Immunomodulatory peptides that target a pathogen and modulate the immune system simultaneously are promising for the development of preventive and therapeutic molecules. Since investigating innate immunity in insects has led to prominent achievements in human immunology, such as toll-like receptor (TLR) discovery, we used the capacity of the immunomodulatory peptides of arthropods with concomitant antimicrobial or antitumor activity. An SVM-based machine learning classifier identified short immunomodulatory sequences encrypted in 643 antimicrobial peptides from 55 foe-to-friend arthropods. The critical features involved in efficacy and safety were calculated. Finally, 76 safe immunomodulators were identified. Then, molecular docking and simulation studies defined the target of the most optimal peptide ligands among all human cell-surface TLRs. SPalf2-453 from a crab is a cell-penetrating immunoadjuvant with antiviral properties. The peptide interacts with the TLR1/2 heterodimer. SBsib-711 from a blackfly is a TLR4/MD2 ligand used as a cancer vaccine immunoadjuvant. In addition, SBsib-711 binds CD47 and PD-L1 on tumor cells, which is applicable in cancer immunotherapy as a checkpoint inhibitor. MRh4-679 from a shrimp is a broad-spectrum or universal immunoadjuvant with a putative Th1/Th2-balanced response. We also implemented a pathway enrichment analysis to define fingerprints or immunological signatures for further in vitro and in vivo immunogenicity and reactogenicity measurements. Conclusively, combinatorial machine learning, molecular docking, and simulation studies, as well as systems biology, open a new opportunity for the discovery and development of multifunctional prophylactic and therapeutic lead peptides.
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Affiliation(s)
- Shiva Hemmati
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz 71345-1583, Iran
- Biotechnology Research Center, Shiraz University of Medical Sciences, Shiraz 71345-1583, Iran
- Department of Pharmaceutical Biology, Faculty of Pharmaceutical Sciences, UCSI University, Cheras, Kuala Lumpur 56000, Malaysia
| | - Zahra Saeidikia
- Student Research Committee, Shiraz University of Medical Sciences, Shiraz 71345-1583, Iran;
| | - Hassan Seradj
- Department of Medicinal Chemistry, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz 71345-1583, Iran;
| | - Abdolali Mohagheghzadeh
- Department of Phytopharmaceuticals, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz 71345-1583, Iran;
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Solanki SS, Singh P, Kashyap P, Sansi MS, Ali SA. Promising role of defensins peptides as therapeutics to combat against viral infection. Microb Pathog 2021; 155:104930. [PMID: 33933603 PMCID: PMC8084285 DOI: 10.1016/j.micpath.2021.104930] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/13/2022]
Abstract
Antimicrobial peptides (AMPs) are ubiquitously present small peptides, which play a critical function in the innate immune system. The defensin class of AMPs represented an evolutionarily ancient family containing cationic cysteine residue and frequently expressed in epithelial or neutrophils cells. It plays myriad functions in host innate immune responses against various infection. Defensin has a broad spectrum of antimicrobial activities, including anti-bacteria, anti-viruses (AVPs), anti-fungi, anti-cancers, and also overcoming bacterial drug resistance. In this review, we compiled the progress on defensin, particularly incorporating the mechanism of action, their application as an antiviral agent, prospects in different areas, and limitations to be solved as an antiviral peptide. Defensins were explored, in particular, their capacity to stimulate innate and adaptive immunity by trigging as anti-coronavirus (COVID-19) peptides. The present review summarised its immunomodulatory and immunoenhancing properties and predominantly focused on its promising therapeutic adjuvant choices for combat against viral infection.
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Affiliation(s)
| | - Parul Singh
- Cell Biology and Proteomics Lab, Animal Biotechnology Centre, National Dairy Research Institute, Karnal, 132001, Haryana, India
| | - Poonam Kashyap
- Animal Genomics Lab, National Dairy Research Institute, Karnal, 132001, India
| | - Manish Singh Sansi
- Animal Biochemistry Division, National Dairy Research Institute, Karnal, 132001, Haryana, India
| | - Syed Azmal Ali
- Cell Biology and Proteomics Lab, Animal Biotechnology Centre, National Dairy Research Institute, Karnal, 132001, Haryana, India; Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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4
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Immunoregulatory and Antimicrobial Activity of Bovine Neutrophil β-Defensin-5-Loaded PLGA Nanoparticles against Mycobacterium bovis. Pharmaceutics 2020; 12:pharmaceutics12121172. [PMID: 33271900 PMCID: PMC7760669 DOI: 10.3390/pharmaceutics12121172] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 01/28/2023] Open
Abstract
Mycobacterium bovis (M. bovis) is a member of the Mycobacterium tuberculosis complex imposing a high zoonotic threat to human health. The limited efficacy of BCG (Bacillus Calmette-Guérin) and upsurges of drug-resistant tuberculosis require new effective vaccination approaches and anti-TB drugs. Poly (lactic-co-glycolic acid) (PLGA) is a preferential drug delivery system candidate. In this study, we formulated PLGA nanoparticles (NPs) encapsulating the recombinant protein bovine neutrophil β-defensin-5 (B5), and investigated its role in immunomodulation and antimicrobial activity against M. bovis challenge. Using the classical water-oil-water solvent-evaporation method, B5-NPs were prepared, with encapsulation efficiency of 85.5% ± 2.5%. These spherical NPs were 206.6 ± 26.6 nm in diameter, with a negatively charged surface (ζ-potential -27.1 ± 1.5 mV). The encapsulated B5 protein from B5-NPs was released slowly under physiological conditions. B5 or B5-NPs efficiently enhanced the secretion of tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-10 in J774A.1 macrophages. B5-NPs-immunized mice showed significant increases in the production of TNF-α and immunoglobulin A (IgA) in serum, and the proportion of CD4+ T cells in spleen compared with B5 alone. In immunoprotection studies, B5-NPs-immunized mice displayed significant reductions in pulmonary inflammatory area, bacterial burden in the lungs and spleen at 4-week after M. bovis challenge. In treatment studies, B5, but not B5-NPs, assisted rifampicin (RIF) with inhibition of bacterial replication in the lungs and spleen. Moreover, B5 alone also significantly reduced the bacterial load in the lungs and spleen. Altogether, our findings highlight the significance of the B5-PLGA NPs in terms of promoting the immune effect of BCG and the B5 in enhancing the therapeutic effect of RIF against M. bovis.
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Ryan LK, Hise AG, Hossain CM, Ruddick W, Parveen R, Freeman KB, Weaver DG, Narra HP, Scott RW, Diamond G. A Novel Immunocompetent Mouse Model for Testing Antifungal Drugs Against Invasive Candida albicans Infection. J Fungi (Basel) 2020; 6:E197. [PMID: 33007818 PMCID: PMC7712810 DOI: 10.3390/jof6040197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/22/2020] [Accepted: 09/28/2020] [Indexed: 12/12/2022] Open
Abstract
Disseminated infection by Candida species represents a common, often life-threatening condition. Increased resistance to current antifungal drugs has led to an urgent need to develop new antifungal drugs to treat this pathogen. However, in vivo screening of candidate antifungal compounds requires large numbers of animals and using immunosuppressive agents to allow for fungal dissemination. To increase the efficiency of screening, to use fewer mice, and to remove the need for immunosuppressive agents, which may interfere with the drug candidates, we tested the potential for a novel approach using in vivo imaging of a fluorescent strain of Candida albicans, in a mouse strain deficient in the host defense peptide, murine β-defensin 1 (mBD-1). We developed a strain of C. albicans that expresses red fluorescent protein (RFP), which exhibits similar infectivity to the non-fluorescent parent strain. When this strain was injected into immunocompetent mBD-1-deficient mice, we observed a non-lethal disseminated infection. Further, we could quantify its dissemination in real time, and observe the activity of an antifungal peptide mimetic drug by in vivo imaging. This novel method will allow for the rapid in vivo screening of antifungal drugs, using fewer mice, and increase the efficiency of testing new antifungal agents.
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Affiliation(s)
- Lisa K. Ryan
- Division of Infectious Disease and Global Medicine, Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32610, USA;
| | - Amy G Hise
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA;
- Medicine Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA
| | - Chowdhury Mobaswar Hossain
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA; (C.M.H.); (W.R.); (R.P.)
| | - William Ruddick
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA; (C.M.H.); (W.R.); (R.P.)
| | - Rezwana Parveen
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA; (C.M.H.); (W.R.); (R.P.)
| | - Katie B. Freeman
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, Doylestown, PA 18902, USA; (K.B.F.); (D.G.W.); (R.W.S.)
| | - Damian G. Weaver
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, Doylestown, PA 18902, USA; (K.B.F.); (D.G.W.); (R.W.S.)
| | - Hema P. Narra
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Richard W. Scott
- Fox Chase Chemical Diversity Center, Inc., Pennsylvania Biotechnology Center, Doylestown, PA 18902, USA; (K.B.F.); (D.G.W.); (R.W.S.)
| | - Gill Diamond
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA; (C.M.H.); (W.R.); (R.P.)
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY 40902, USA
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Kamanova J. Bordetella Type III Secretion Injectosome and Effector Proteins. Front Cell Infect Microbiol 2020; 10:466. [PMID: 33014891 PMCID: PMC7498569 DOI: 10.3389/fcimb.2020.00466] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 07/29/2020] [Indexed: 01/09/2023] Open
Abstract
Pertussis, also known as whooping cough, is a resurging acute respiratory disease of humans primarily caused by the Gram-negative coccobacilli Bordetella pertussis, and less commonly by the human-adapted lineage of B. parapertussis HU. The ovine-adapted lineage of B. parapertussis OV infects only sheep, while B. bronchiseptica causes chronic and often asymptomatic respiratory infections in a broad range of mammals but rarely in humans. A largely overlapping set of virulence factors inflicts the pathogenicity of these bordetellae. Their genomes also harbor a pathogenicity island, named bsc locus, that encodes components of the type III secretion injectosome, and adjacent btr locus with the type III regulatory proteins. The Bsc injectosome of bordetellae translocates the cytotoxic BteA effector protein, also referred to as BopC, into the cells of the mammalian hosts. While the role of type III secretion activity in the persistent colonization of the lower respiratory tract by B. bronchiseptica is well recognized, the functionality of the type III secretion injectosome in B. pertussis was overlooked for many years due to the adaptation of laboratory-passaged B. pertussis strains. This review highlights the current knowledge of the type III secretion system in the so-called classical Bordetella species, comprising B. pertussis, B. parapertussis, and B. bronchiseptica, and discusses its functional divergence. Comparison with other well-studied bacterial injectosomes, regulation of the type III secretion on the transcriptional and post-transcriptional level, and activities of BteA effector protein and BopN protein, homologous to the type III secretion gatekeepers, are addressed.
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Affiliation(s)
- Jana Kamanova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
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7
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Bayram J, Malcova I, Sinkovec L, Holubova J, Streparola G, Jurnecka D, Kucera J, Sedlacek R, Sebo P, Kamanova J. Cytotoxicity of the effector protein BteA was attenuated in Bordetella pertussis by insertion of an alanine residue. PLoS Pathog 2020; 16:e1008512. [PMID: 32776984 PMCID: PMC7446853 DOI: 10.1371/journal.ppat.1008512] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 08/20/2020] [Accepted: 06/24/2020] [Indexed: 11/30/2022] Open
Abstract
Bordetella bronchiseptica and Bordetella pertussis are closely related respiratory pathogens that evolved from a common bacterial ancestor. While B. bronchiseptica has an environmental reservoir and mostly establishes chronic infections in a broad range of mammals, B. pertussis is a human-specific pathogen causing acute pulmonary pertussis in infants and whooping cough illness in older humans. Both species employ a type III secretion system (T3SS) to inject a cytotoxic BteA effector protein into host cells. However, compared to the high BteA-mediated cytotoxicity of B. bronchiseptica, the cytotoxicity induced by B. pertussis BteA (Bp BteA) appears to be quite low and this has been attributed to the reduced T3SS gene expression in B. pertussis. We show that the presence of an alanine residue inserted at position 503 (A503) of Bp BteA accounts for its strongly attenuated cytotoxic potency. The deletion of A503 from Bp BteA greatly enhanced the cytotoxic activity of B. pertussis B1917 on mammalian HeLa cells and expression of Bp BteAΔA503 was highly toxic to Saccharomyces cerevisiae cells. Vice versa, insertion of A503 into B. bronchiseptica BteA (Bb BteA) strongly decreased its cytotoxicity to yeast and HeLa cells. Moreover, the production of Bp BteAΔA503 increased virulence of B. pertussis B1917 in the mouse model of intranasal infection (reduced LD50) but yielded less inflammatory pathology in infected mouse lungs at sublethal infectious doses. This suggests that A503 insertion in the T3SS effector Bp BteA may represent an evolutionary adaptation that fine-tunes B. pertussis virulence and host immune response. Pertussis remains the least-controlled vaccine-preventable infectious disease and the mechanisms by which Bordetella pertussis subverts defense mechanisms of human airway mucosa remain poorly understood. We found that B. pertussis had the cytotoxic activity of its type III secretion system-delivered effector BteA strongly attenuated by insertion of an alanine residue at position 503 as compared to the BteA homologue of the animal pathogen B. bronchiseptica. This functional adaptation reduced the capacity of B. pertussis to suppress host inflammatory response and may contribute to an acute course of the pulmonary form of human infant pertussis.
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Affiliation(s)
- Jan Bayram
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ivana Malcova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Larisa Sinkovec
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Holubova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Gaia Streparola
- Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Kucera
- Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Radislav Sedlacek
- Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Kamanova
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
- * E-mail:
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8
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Molecular characterization of pulmonary defenses against bacterial invasion in allergic asthma: The role of Foxa2 in regulation of β-defensin 1. PLoS One 2019; 14:e0226517. [PMID: 31881038 PMCID: PMC6934329 DOI: 10.1371/journal.pone.0226517] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/26/2019] [Indexed: 02/05/2023] Open
Abstract
Allergic asthma, characterized by chronic airway Th2-dominated inflammation, is associated with an increased risk of infection; however, the underlying mechanisms are unclear. Forkhead box protein A2 (Foxa2) plays a critical role in Th2 inflammation and is associated with pulmonary defenses. To determining the role of Foxa2 in Th2-dominated lung inflammation against the invading bacteria, we established a mouse OVA-sensitized model, an Escherichia coli lung invasion model, and mice with conditional deletion of Foxa2 in respiratory epithelial cells. The number of bacteria in the lung tissue was counted to assess clearance ability of lung. Lung inflammation and histopathology was evaluated using HE and PAS staining. It was found that OVA-sensitized mice had decreased E. coli clearance, reduced Foxa2 expression, and decreased DEFB1 secretion. Conditional deletion of Foxa2 in respiratory epithelial cells led to decreased clearance of E. coli and impaired secretion of DEFB1, similar to the OVA-induced allergic condition. The impaired secretion of DEFB1 may be responsible for the increased risk of infection in the Th2-dominated airway inflammation. Dual luciferase assay demonstrated that Foxa2 regulates DEFB1 expression by affecting its promoter activity in HBE cells. Our study indicated that Foxa2 plays an important role in Th2-dominated airway inflammation against invading bacteria. Conditional deletion of Foxa2 in respiratory epithelial cells can reduce pulmonary's defense against bacterial invasion by inhibiting DEFB1expression.
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Huang C, Yang X, Huang J, Liu X, Yang X, Jin H, Huang Q, Li L, Zhou R. Porcine Beta-Defensin 2 Provides Protection Against Bacterial Infection by a Direct Bactericidal Activity and Alleviates Inflammation via Interference With the TLR4/NF-κB Pathway. Front Immunol 2019; 10:1673. [PMID: 31379864 PMCID: PMC6657668 DOI: 10.3389/fimmu.2019.01673] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 07/04/2019] [Indexed: 12/15/2022] Open
Abstract
Porcine beta-defensin 2 (PBD-2) which is a member of the family of antimicrobial peptides, is widely expressed in pig organs with a broad spectrum of bactericidal activities confirmed in vitro. We previously demonstrated that transgenic (TG) pigs overexpressing PBD-2 could resist the infection by the porcine pathogen Actinobacillus pleuropneumoniae. In this study, the roles of PBD-2 in protecting against bacterial infection were further investigated. The biochemical indexes of the blood sample, body weights, histological morphologies, and weights of the organs of TG mice expressing PBD-2 were measured. Results confirmed that these mice showed normal physiological features. An assay of Salmonella Typhimurium infection was conducted on wild-type (WT) and TG mice. The TG mice possessed higher survival rate, less body weight loss, and pathological changes and smaller recovery rates of bacteria after infection with S. Typhimurium. The in vitro synthetic PBD-2 and the serum and tissue homogenates from the TG mice displayed a direct bactericidal activity. Moreover, PBD-2 could inhibit the release of the proinflammatory cytokines, including IL-6, TNF-α, IL-1β, and IL-12, in the TG mice infected with S. Typhimurium or treated with lipopolysaccharide (LPS). The WT mice treated with PBD-2 and S. Typhimurium or LPS showed reduced levels of proinflammatory cytokines. The mouse macrophage cell line RAW 264.7 which expressed PBD-2 was constructed to detect the signal pathways affected by PBD-2. The suppressing effect of PBD-2 on the release of the proinflammatory cytokines was confirmed using RAW 264.7 either expressing PBD-2 or supplemented with PBD-2. The promoter activity and mRNA level of NF-κB were detected, and PBD-2 was shown to significantly inhibit the activation of the NF-κB pathway induced by LPS. The direct interaction of PBD-2 with TLR4 was revealed by isothermal titration calorimetry and far-Western blot in vitro and the coimmunoprecipitation of PBD-2 with TLR4 on RAW 264.7 cells. This interaction indicates one reason for the interference of NF-κB activation. Overall, this study showed that PBD-2 protected against bacterial infection through a direct bactericidal activity and alleviated inflammation by interfering with the TLR4/NF-κB pathway.
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Affiliation(s)
- Chao Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Xi Yang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Pig Industry Sciences, Chongqing Academy of Animal Sciences, Chongqing, China
| | - Jing Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Xiao Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Xiaoyu Yang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, China
| | - Hui Jin
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Qi Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, China.,International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, China
| | - Lu Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, China.,International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, China
| | - Rui Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.,Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, China.,International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, China
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