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Naseef Pathoor N, Viswanathan A, Wadhwa G, Ganesh PS. Understanding the biofilm development of Acinetobacter baumannii and novel strategies to combat infection. APMIS 2024; 132:317-335. [PMID: 38444124 DOI: 10.1111/apm.13399] [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: 12/08/2023] [Accepted: 02/22/2024] [Indexed: 03/07/2024]
Abstract
Acinetobacter baumannii (A. baumannii) is a Gram-negative, nonmotile, and aerobic bacillus emerged as a superbug, due to increasing the possibility of infection and accelerating rates of antimicrobial agents. It is recognized as a nosocomial pathogen due to its ability to form biofilms. These biofilms serve as a defensive barrier, increase antibiotic resistance, and make treatment more difficult. As a result, the current situation necessitates the rapid emergence of novel therapeutic approaches to ensure successful treatment outcomes. This review explores the intricate relationship between biofilm formation and antibiotic resistance in A. baumannii, emphasizing the role of key virulence factors and quorum sensing (QS) mechanisms that will lead to infections and facilitate insight into developing innovative method to control A. baumannii infections. Furthermore, the review article looks into promising approaches for preventing biofilm formation on medically important surfaces and potential therapeutic methods for eliminating preformed biofilms, which can address biofilm-associated A. baumannii infections. Modern advances in emerging therapeutic options such as antimicrobial peptide (AMPs), nanoparticles (NPs), bacteriophage therapy, photodynamic therapy (PDT), and other biofilm inhibitors can assist readers understand the current landscape and future prospects for effectively treating A. baumannii biofilm infections.
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Affiliation(s)
- Naji Naseef Pathoor
- Department of Microbiology, Centre for Infectious Diseases, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University (Deemed to be University), Chennai, Tamil Nadu, India
| | - Akshaya Viswanathan
- Department of Microbiology, Centre for Infectious Diseases, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University (Deemed to be University), Chennai, Tamil Nadu, India
| | - Gulshan Wadhwa
- Department of Biotechnology, Ministry of Science and Technology, New Delhi, India
| | - Pitchaipillai Sankar Ganesh
- Department of Microbiology, Centre for Infectious Diseases, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University (Deemed to be University), Chennai, Tamil Nadu, India
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Jeffreys S, Tompkins MP, Aki J, Papp SB, Chambers JP, Guentzel MN, Hung CY, Yu JJ, Arulanandam BP. Development and Evaluation of an Immunoinformatics-Based Multi-Peptide Vaccine against Acinetobacter baumannii Infection. Vaccines (Basel) 2024; 12:358. [PMID: 38675740 PMCID: PMC11054912 DOI: 10.3390/vaccines12040358] [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: 02/27/2024] [Revised: 03/21/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Multi-drug-resistant (MDR) Acinetobacter baumannii is an opportunistic pathogen associated with hospital-acquired infections. Due to its environmental persistence, virulence, and limited treatment options, this organism causes both increased patient mortality and incurred healthcare costs. Thus, prophylactic vaccination could be ideal for intervention against MDR Acinetobacter infection in susceptible populations. In this study, we employed immunoinformatics to identify peptides containing both putative B- and T-cell epitopes from proteins associated with A. baumannii pathogenesis. A novel Acinetobacter Multi-Epitope Vaccine (AMEV2) was constructed using an A. baumannii thioredoxin A (TrxA) leading protein sequence followed by five identified peptide antigens. Antisera from A. baumannii infected mice demonstrated reactivity to rAMEV2, and subcutaneous immunization of mice with rAMEV2 produced high antibody titer against the construct as well as peptide components. Immunization results in increased frequency of IL-4-secreting splenocytes indicative of a Th2 response. AMEV2-immunized mice were protected against intranasal challenge with a hypervirulent strain of A. baumannii and demonstrated reduced bacterial burden at 48 h. In contrast, all mock vaccinated mice succumbed to infection within 3 days. Results presented here provide insight into the effectiveness of immunoinformatic-based vaccine design and its potential as an effective strategy to combat the rise of MDR pathogens.
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Affiliation(s)
- Sean Jeffreys
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Megan P. Tompkins
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Jadelynn Aki
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Sara B. Papp
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - James P. Chambers
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - M. Neal Guentzel
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Chiung-Yu Hung
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Jieh-Juen Yu
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Bernard P. Arulanandam
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
- Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA
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Weng Z, Yang N, Shi S, Xu Z, Chen Z, Liang C, Zhang X, Du X. Outer Membrane Vesicles from Acinetobacter baumannii: Biogenesis, Functions, and Vaccine Application. Vaccines (Basel) 2023; 12:49. [PMID: 38250862 PMCID: PMC10818702 DOI: 10.3390/vaccines12010049] [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: 11/16/2023] [Revised: 12/25/2023] [Accepted: 12/29/2023] [Indexed: 01/23/2024] Open
Abstract
This review focuses on Acinetobacter baumannii, a Gram-negative bacterium that causes various infections and whose multidrug resistance has become a significant challenge in clinical practices. There are multiple bacterial mechanisms in A. baumannii that participate in bacterial colonization and immune responses. It is believed that outer membrane vesicles (OMVs) budding from the bacteria play a significant role in mediating bacterial survival and the subsequent attack against the host. Most OMVs originate from the bacterial membranes and molecules are enveloped in them. Elements similar to the pathogen endow OMVs with robust virulence, which provides a new direction for exploring the pathogenicity of A. baumannii and its therapeutic pathways. Although extensive research has been carried out on the feasibility of OMV-based vaccines against pathogens, no study has yet summarized the bioactive elements, biological activity, and vaccine applicability of A. baumannii OMVs. This review summarizes the components, biogenesis, and function of OMVs that contribute to their potential as vaccine candidates and the preparation methods and future directions for their development.
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Affiliation(s)
- Zheqi Weng
- The Second Clinical Medical School, Nanjing Medical University, Nanjing 210011, China
| | - Ning Yang
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing 210011, China
| | - Shujun Shi
- The Second Clinical Medical School, Nanjing Medical University, Nanjing 210011, China
| | - Zining Xu
- The Second Clinical Medical School, Nanjing Medical University, Nanjing 210011, China
| | - Zixu Chen
- The Second Clinical Medical School, Nanjing Medical University, Nanjing 210011, China
| | - Chen Liang
- The Second Clinical Medical School, Nanjing Medical University, Nanjing 210011, China
| | - Xiuwei Zhang
- Department of Respiratory and Critical Care Medicine, The Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing 211100, China
| | - Xingran Du
- Department of Respiratory and Critical Care Medicine, The Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing 211100, China
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Sadeghi L, Mohit E, Moallemi S, Ahmadi FM, Bolhassani A. Recent advances in various bio-applications of bacteria-derived outer membrane vesicles. Microb Pathog 2023; 185:106440. [PMID: 37931826 DOI: 10.1016/j.micpath.2023.106440] [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: 06/24/2023] [Revised: 10/12/2023] [Accepted: 11/02/2023] [Indexed: 11/08/2023]
Abstract
Outer membrane vesicles (OMVs) are spherical nanoparticles released from gram-negative bacteria. OMVs were originally classified into native 'nOMVs' (produced naturally from budding of bacteria) and non-native (produced by mechanical means). nOMVs and detergent (dOMVs) are isolated from cell supernatant without any detergent cell disruption techniques and through detergent extraction, respectively. Growth stages and conditions e.g. different stress factors, including temperature, nutrition deficiency, and exposure to hazardous chemical agents can affect the yield of OMVs production and OMVs content. Because of the presence of bacterial antigens, pathogen-associated molecular patterns (PAMPs), various proteins and the vesicle structure, OMVs have been developed in many biomedical applications. OMVs due to their size can be phagocytized by APCs, enter lymph vessels, transport antigens efficiently, and induce both T and B cells immune responses. Non-engineered OMVs have been frequently used as vaccines against different bacterial and viral infections, and various cancers. OMVs can also be used in combination with different antigens as an attractive vaccine adjuvant. Indeed, foreign antigens from target microorganisms can be trapped in the lumen of nonpathogenic vesicles or can be displayed on the surface through bacterial membrane protein to increase the immunogenicity of the antigens. In this review, different factors affecting OMV production including time of cultivation, growth media, stress conditions and genetic manipulations to enhance vesiculation will be described. Furthermore, recent advances in various biological applications of OMVs such as vaccine, drug delivery, cancer therapy, and enzyme carrier are discussed. Generally, the application of OMVs as vaccine carrier in three categories (i.e., non-engineered OMVs, OMVs as an adjuvant, recombinant OMVs (rOMVs)), as delivery system for small interfering RNA and therapeutic agents, and as enzymes carrier will be discussed.
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Affiliation(s)
- Leila Sadeghi
- Department of Hepatitis and AIDS, Pasteur Institute of Iran, Tehran, Iran
| | - Elham Mohit
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Protein Technology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Samaneh Moallemi
- School of Biomedical Sciences, Faculty of Medicine, UNSW Sydney, NSW, 2052, Australia
| | | | - Azam Bolhassani
- Department of Hepatitis and AIDS, Pasteur Institute of Iran, Tehran, Iran.
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Park J, Woo SJ, Hong Y, Lee JJ, Hong JY. Association between the Respiratory Microbiome and Plasma Microbial Extracellular Vesicles in Intubated Patients. Microorganisms 2023; 11:2128. [PMID: 37763972 PMCID: PMC10537887 DOI: 10.3390/microorganisms11092128] [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: 07/21/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Extracellular vesicles (EVs) regulate various cellular and immunological functions in human diseases. There is growing interest in the clinical role of microbial EVs in pneumonia. However, there is a lack of research on the correlation between lung microbiome with microbial EVs and the microbiome of other body sites in pneumonia. We investigated the co-occurrence of lung microbiome and plasma microbe-derived EVs (mEVs) in 111 samples obtained from 60 mechanically ventilated patients (41 pneumonia and 19 non-pneumonia cases). The microbial correlation between the two samples was compared between the pneumonia and non-pneumonia cases. Bacterial composition of the plasma mEVs was distinct from that of the lung microbiome. There was a significantly higher correlation between lung microbiome and plasma mEVs in non-pneumonia individuals compared to pneumonia patients. In particular, Acinetobacter and Lactobacillus genera had high correlation coefficients in non-pneumonia patients. This indicates a beneficial effect of mEVs in modulating host lung immune response through EV component transfer.
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Affiliation(s)
- Jinkyeong Park
- Department of Pulmonary, Allergy and Critical Care Medicine, Kyung Hee University Hospital at Gangdong, School of Medicine, Kyung Hee University, Seoul 05278, Republic of Korea;
| | - Seong Ji Woo
- Institute of New Frontier Research Team, Hallym University College of Medicine, Chuncheon 24253, Republic of Korea; (S.J.W.); (J.J.L.)
| | - Yoonki Hong
- Department of Internal Medicine, Kangwon National University Hospital, School of Medicine, Kangwon National University, Chuncheon 24289, Republic of Korea;
| | - Jae Jun Lee
- Institute of New Frontier Research Team, Hallym University College of Medicine, Chuncheon 24253, Republic of Korea; (S.J.W.); (J.J.L.)
| | - Ji Young Hong
- Institute of New Frontier Research Team, Hallym University College of Medicine, Chuncheon 24253, Republic of Korea; (S.J.W.); (J.J.L.)
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Chuncheon Sacred Heart Hospital, Hallym University Medical Center, Chuncheon 24253, Republic of Korea
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Jeffreys S, Chambers JP, Yu JJ, Hung CY, Forsthuber T, Arulanandam BP. Insights into Acinetobacter baumannii protective immunity. Front Immunol 2022; 13:1070424. [PMID: 36466845 PMCID: PMC9716351 DOI: 10.3389/fimmu.2022.1070424] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022] Open
Abstract
Acinetobacter baumannii is a nosocomic opportunistic Gram-negative bacteria known for its extensive drug-resistant phenotype. A. baumannii hospital-acquired infections are major contributors to increased costs and mortality observed during the COVID-19 pandemic. With few effective antimicrobials available for treatment of this pathogen, immune-based therapy becomes an attractive strategy to combat multi-drug resistant Acinetobacter infection. Immunotherapeutics is a field of growing interest with advances in vaccines and monoclonal antibodies providing insight into the protective immune response required to successfully combat this pathogen. This review focuses on current knowledge describing the adaptive immune response to A. baumannii, the importance of antibody-mediated protection, developments in cell-mediated protection, and their respective therapeutic application going forward. With A. baumannii’s increasing resistance to most current antimicrobials, elucidating an effective host adaptive immune response is paramount in the guidance of future immunotherapeutic development.
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Affiliation(s)
- Sean Jeffreys
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - James P. Chambers
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Jieh-Juen Yu
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Chiung-Yu Hung
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Thomas Forsthuber
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Bernard P. Arulanandam
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
- Department of Immunology, Tufts University School of Medicine, Boston, MA, United States
- *Correspondence: Bernard P. Arulanandam,
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Long Q, Zheng P, Zheng X, Li W, Hua L, Yang Z, Huang W, Ma Y. Engineered bacterial membrane vesicles are promising carriers for vaccine design and tumor immunotherapy. Adv Drug Deliv Rev 2022; 186:114321. [PMID: 35533789 DOI: 10.1016/j.addr.2022.114321] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/18/2022] [Accepted: 04/30/2022] [Indexed: 02/06/2023]
Abstract
Bacterial membrane vesicles (BMVs) have emerged as novel and promising platforms for the development of vaccines and immunotherapeutic strategies against infectious and noninfectious diseases. The rich microbe-associated molecular patterns (MAMPs) and nanoscale membrane vesicle structure of BMVs make them highly immunogenic. In addition, BMVs can be endowed with more functions via genetic and chemical modifications. This article reviews the immunological characteristics and effects of BMVs, techniques for BMV production and modification, and the applications of BMVs as vaccines or vaccine carriers. In summary, given their versatile characteristics and immunomodulatory properties, BMVs can be used for clinical vaccine or immunotherapy applications.
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Bacterial Outer Membrane Vesicles as a Versatile Tool in Vaccine Research and the Fight against Antimicrobial Resistance. mBio 2021; 12:e0170721. [PMID: 34372691 PMCID: PMC8406158 DOI: 10.1128/mbio.01707-21] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gram-negative bacteria include a number of pathogens that cause disease in humans and animals. Although antibiotics are still effective in treating a considerable range of infections caused by Gram-negative bacteria, the alarming increase of antimicrobial resistance (AMR) induced by excessive use of antibiotics has raised global concerns. Therefore, alternative strategies must be developed to prevent and treat bacterial infections and prevent the advent of a postantibiotic era. Vaccines, one of the greatest achievements in the history of medical science, hold extraordinary potential to prevent bacterial infections and thereby reduce the need for antibiotics. Novel bacterial vaccines are urgently needed, however, and outer membrane vesicles (OMVs), naturally produced by Gram-negative bacteria, represent a promising and versatile tool that can be employed as adjuvants, antigens, and delivery platforms in the development of vaccines against Gram-negative bacteria. Here, we provide an overview of the many roles OMVs can play in vaccine development and the mechanisms behind these applications. Methods to improve OMV yields and a comparison of different strategies for OMV isolation aiming at cost-effective production of OMV-based vaccines are also reviewed.
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Zingl FG, Leitner DR, Thapa HB, Schild S. Outer membrane vesicles as versatile tools for therapeutic approaches. MICROLIFE 2021; 2:uqab006. [PMID: 37223254 PMCID: PMC10117751 DOI: 10.1093/femsml/uqab006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/05/2021] [Indexed: 05/25/2023]
Abstract
Budding of the bacterial surface results in the formation and secretion of outer membrane vesicles, which is a conserved phenomenon observed in Gram-negative bacteria. Recent studies highlight that these sphere-shaped facsimiles of the donor bacterium's surface with enclosed periplasmic content may serve multiple purposes for their host bacterium. These include inter- and intraspecies cell-cell communication, effector delivery to target cells and bacterial adaptation strategies. This review provides a concise overview of potential medical applications to exploit outer membrane vesicles for therapeutic approaches. Due to the fact that outer membrane vesicles resemble the surface of their donor cells, they represent interesting nonliving candidates for vaccine development. Furthermore, bacterial donor species can be genetically engineered to display various proteins and glycans of interest on the outer membrane vesicle surface or in their lumen. Outer membrane vesicles also possess valuable bioreactor features as they have the natural capacity to protect, stabilize and enhance the activity of luminal enzymes. Along these features, outer membrane vesicles not only might be suitable for biotechnological applications but may also enable cell-specific delivery of designed therapeutics as they are efficiently internalized by nonprofessional phagocytes. Finally, outer membrane vesicles are potent modulators of our immune system with pro- and anti-inflammatory properties. A deeper understanding of immunoregulatory effects provoked by different outer membrane vesicles is the basis for their possible future applications ranging from inflammation and immune response modulation to anticancer therapy.
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Affiliation(s)
- Franz G Zingl
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Deborah R Leitner
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Himadri B Thapa
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria
- BioTechMed-Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
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Liu AR, Du WJ, Xie JF, Xu JY, Huang YZ, Qiu HB, Yang Y. Role of immunodeficiency in Acinetobacter baumannii associated pneumonia in mice. Chin Med J (Engl) 2021; 133:2161-2169. [PMID: 32842019 PMCID: PMC7508442 DOI: 10.1097/cm9.0000000000001027] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background Acinetobacter baumannii (A. baumannii) has become one of the most important opportunistic pathogens inducing nosocomial pneumonia and increasing mortality in critically ill patients recently. The interaction between A. baumannii infection and immune response can influence the prognosis of A. baumannii related pneumonia. The target of the present study was to investigate the role of immunodeficiency in A. baumannii induced pneumonia. Methods Male BALB/c mice were randomly divided into the normal immunity control (NIC) group, normal immunity infection (NIA) group, immune compromised control (CIC) group, and immune compromised infection (CIA) group (n = 15 for each group). Intraperitoneal injection of cyclophosphamide and intranasal instillation of A. baumannii solution were used to induce compromised immunity and murine pneumonia, respectively. The mice were sacrificed at 6 and 24 h later and the specimens were collected for further tests. Seven-day mortality of mice was also assessed. Results After A. baumannii stimulation, the recruitment of neutrophils in mice with normal immunity increased sharply (P = 0.030 at 6 h), while there was no significant raise of neutrophil counts in mice with compromised immune condition (P = 0.092 at 6 h, P = 0.772 at 24 h). The Th cell polarization presented with pulmonary interleukin (IL)-4 and interferon (IFN)-γ level in response to the A. baumannii in CIA group were significantly depressed in comparison with in NIA group (IFN-γ: P = 0.003 at 6 h; P = 0.001 at 24 h; IL-4: P < 0.001 at 6 h; P < 0.001 at 24 h). The pulmonary conventional dendritic cell accumulation was even found to be inhibited after A. baumannii infection in immunocompromised mice (P = 0.033). Correspondingly, A. baumannii associated pneumonia in mice with compromised immunity caused more early stage death, more severe histopathological impairment in lung. Conclusion A. baumannii could frustrate the immune response in immunocompromised conditions, and this reduced immune response is related to more severe lung injury and worse outcome in A. baumannii induced pneumonia.
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Affiliation(s)
- Ai-Ran Liu
- Department of Critical Care Medicine, Zhong-Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, China
| | - Wen-Jing Du
- Department of Critical Care Medicine, Xuzhou Central Hospital, Xuzhou, Jiangsu 221009, China
| | - Jian-Feng Xie
- Department of Critical Care Medicine, Zhong-Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, China
| | - Jing-Yuan Xu
- Department of Critical Care Medicine, Zhong-Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, China
| | - Ying-Zi Huang
- Department of Critical Care Medicine, Zhong-Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, China
| | - Hai-Bo Qiu
- Department of Critical Care Medicine, Zhong-Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, China
| | - Yi Yang
- Department of Critical Care Medicine, Zhong-Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, China
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Behrens F, Funk-Hilsdorf TC, Kuebler WM, Simmons S. Bacterial Membrane Vesicles in Pneumonia: From Mediators of Virulence to Innovative Vaccine Candidates. Int J Mol Sci 2021; 22:3858. [PMID: 33917862 PMCID: PMC8068278 DOI: 10.3390/ijms22083858] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 04/03/2021] [Accepted: 04/06/2021] [Indexed: 02/07/2023] Open
Abstract
Pneumonia due to respiratory infection with most prominently bacteria, but also viruses, fungi, or parasites is the leading cause of death worldwide among all infectious disease in both adults and infants. The introduction of modern antibiotic treatment regimens and vaccine strategies has helped to lower the burden of bacterial pneumonia, yet due to the unavailability or refusal of vaccines and antimicrobials in parts of the global population, the rise of multidrug resistant pathogens, and high fatality rates even in patients treated with appropriate antibiotics pneumonia remains a global threat. As such, a better understanding of pathogen virulence on the one, and the development of innovative vaccine strategies on the other hand are once again in dire need in the perennial fight of men against microbes. Recent data show that the secretome of bacteria consists not only of soluble mediators of virulence but also to a significant proportion of extracellular vesicles-lipid bilayer-delimited particles that form integral mediators of intercellular communication. Extracellular vesicles are released from cells of all kinds of organisms, including both Gram-negative and Gram-positive bacteria in which case they are commonly termed outer membrane vesicles (OMVs) and membrane vesicles (MVs), respectively. (O)MVs can trigger inflammatory responses to specific pathogens including S. pneumonia, P. aeruginosa, and L. pneumophila and as such, mediate bacterial virulence in pneumonia by challenging the host respiratory epithelium and cellular and humoral immunity. In parallel, however, (O)MVs have recently emerged as auspicious vaccine candidates due to their natural antigenicity and favorable biochemical properties. First studies highlight the efficacy of such vaccines in animal models exposed to (O)MVs from B. pertussis, S. pneumoniae, A. baumannii, and K. pneumoniae. An advanced and balanced recognition of both the detrimental effects of (O)MVs and their immunogenic potential could pave the way to novel treatment strategies in pneumonia and effective preventive approaches.
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Affiliation(s)
- Felix Behrens
- Institute of Physiology, Charité—Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; (F.B.); (T.C.F.-H.); (S.S.)
- Berlin Institute of Health (BIH), 10178 Berlin, Germany
| | - Teresa C. Funk-Hilsdorf
- Institute of Physiology, Charité—Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; (F.B.); (T.C.F.-H.); (S.S.)
| | - Wolfgang M. Kuebler
- Institute of Physiology, Charité—Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; (F.B.); (T.C.F.-H.); (S.S.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10117 Berlin, Germany
- The Keenan Research Centre for Biomedical Science at St. Michael’s, Toronto, ON M5B 1X1, Canada
- Departments of Surgery and Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Szandor Simmons
- Institute of Physiology, Charité—Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; (F.B.); (T.C.F.-H.); (S.S.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 10117 Berlin, Germany
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12
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Ma C, Chen W. Where are we and how far is there to go in the development of an Acinetobacter vaccine? Expert Rev Vaccines 2021; 20:281-295. [PMID: 33554671 DOI: 10.1080/14760584.2021.1887735] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Healthcare-associated infections caused by multidrug-resistant Acinetobacter baumannii are becoming alarming worldwide. However, the pipeline of new antibiotics is very limited. Vaccination is one of the most cost effective and promising strategies to prevent infections and can play an important role in combat multidrug resistance A. baumannii and prevent the development of new drug resistance. AREA COVERED This review gives an overview of the research and development of A. baumannii vaccines during the past five years (2015-2020), discusses the key progresses and current challenges of the field, and speculates on the future of A. baumannii vaccine development. EXPERT OPINION Moderate progresses have been made in the research and development of A. baumannii vaccine in the last five years, in particular in the areas of identification of new protein targets, development of multicomponent vaccines, and use of vaccines and antibodies as adjuncts for antibiotics therapies. However, substantial scientific and logistic challenges, such as selection of lead vaccine candidates and formulation, vaccine clinical trials and targeted population, and financial incentives, remain. Thus, innovative strategies will be needed before an A. baumannii vaccine candidate can be brought into late stage of preclinical development in next five years.
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Affiliation(s)
- Crystal Ma
- Human Health Therapeutics Research Center (HHT), National Research Council Canada, Ottawa, Ontario Canada
| | - Wangxue Chen
- Human Health Therapeutics Research Center (HHT), National Research Council Canada, Ottawa, Ontario Canada.,Department of Biology, Brock University, St. Catharines, Ontario Canada
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Chen W. Host Innate Immune Responses to Acinetobacter baumannii Infection. Front Cell Infect Microbiol 2020; 10:486. [PMID: 33042864 PMCID: PMC7521131 DOI: 10.3389/fcimb.2020.00486] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 08/05/2020] [Indexed: 12/23/2022] Open
Abstract
Acinetobacter baumannii has emerged as a major threat to global public health and is one of the key human pathogens in healthcare (nosocomial and community-acquired)-associated infections. Moreover, A. baumannii rapidly develops resistance to multiple antibiotics and is now globally regarded as a serious multidrug resistant pathogen. There is an urgent need to develop novel vaccines and immunotherapeutics as alternatives to antibiotics for clinical management of A. baumannii infection. However, our knowledge of host immune responses to A. baumannii infection and the identification of novel therapeutic targets are significantly lacking. This review highlights the recent advances and critical gaps in our understanding how A. baumannii interacts with the host innate pattern-recognition receptors, induces a cascade of inflammatory cytokine and chemokine responses, and recruits innate immune effectors (such as neutrophils and macrophages) to the site of infection for effective control of the infection. Such knowledge will facilitate the identification of new targets for the design and development of effective therapeutics and vaccines to fight this emerging threat.
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Affiliation(s)
- Wangxue Chen
- Human Health and Therapeutics (HHT) Research Center, National Research Council Canada, Ottawa, ON, Canada.,Department of Biology, Brock University, St. Catharines, ON, Canada
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