1
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Bernstein KE, Cao D, Shibata T, Saito S, Bernstein EA, Nishi E, Yamashita M, Tourtellotte WG, Zhao TV, Khan Z. Classical and nonclassical effects of angiotensin-converting enzyme: How increased ACE enhances myeloid immune function. J Biol Chem 2024; 300:107388. [PMID: 38763333 PMCID: PMC11208953 DOI: 10.1016/j.jbc.2024.107388] [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: 02/26/2024] [Revised: 05/01/2024] [Accepted: 05/07/2024] [Indexed: 05/21/2024] Open
Abstract
As part of the classical renin-angiotensin system, the peptidase angiotensin-converting enzyme (ACE) makes angiotensin II which has myriad effects on systemic cardiovascular function, inflammation, and cellular proliferation. Less well known is that macrophages and neutrophils make ACE in response to immune activation which has marked effects on myeloid cell function independent of angiotensin II. Here, we discuss both classical (angiotensin) and nonclassical functions of ACE and highlight mice called ACE 10/10 in which genetic manipulation increases ACE expression by macrophages and makes these mice much more resistant to models of tumors, infection, atherosclerosis, and Alzheimer's disease. In another model called NeuACE mice, neutrophils make increased ACE and these mice are much more resistant to infection. In contrast, ACE inhibitors reduce neutrophil killing of bacteria in mice and humans. Increased expression of ACE induces a marked increase in macrophage oxidative metabolism, particularly mitochondrial oxidation of lipids, secondary to increased peroxisome proliferator-activated receptor α expression, and results in increased myeloid cell ATP. ACE present in sperm has a similar metabolic effect, and the lack of ACE activity in these cells reduces both sperm motility and fertilization capacity. These nonclassical effects of ACE are not due to the actions of angiotensin II but to an unknown molecule, probably a peptide, that triggers a profound change in myeloid cell metabolism and function. Purifying and characterizing this peptide could offer a new treatment for several diseases and prove potentially lucrative.
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Affiliation(s)
- Kenneth E Bernstein
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA.
| | - DuoYao Cao
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Tomohiro Shibata
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Suguru Saito
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ellen A Bernstein
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Erika Nishi
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Physiology, São Paulo School of Medicine, Universidade Federal de São Paulo, Sao Paulo, Brazil
| | - Michifumi Yamashita
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Warren G Tourtellotte
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Tuantuan V Zhao
- Research Oncology, Gilead Sciences, Foster City, California, USA
| | - Zakir Khan
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA; Institute for Myeloma & Bone Cancer Research, West Hollywood, California, USA
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2
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Francis D, Bhairaddy A, Joy A, Hari GV, Francis A. Secretory proteins in the orchestration of microbial virulence: The curious case of Staphylococcus aureus. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 133:271-350. [PMID: 36707204 DOI: 10.1016/bs.apcsb.2022.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Microbial virulence showcases an excellent model for adaptive changes that enable an organism to survive and proliferate in a hostile environment and exploit host resources to its own benefit. In Staphylococcus aureus, an opportunistic pathogen of the human host, known for the diversity of the disease conditions it inflicts and the rapid evolution of antibiotic resistance, virulence is a consequence of having a highly plastic genome that is amenable to quick reprogramming and the ability to express a diverse arsenal of virulence factors. Virulence factors that are secreted to the host milieu effectively manipulate the host conditions to favor bacterial survival and growth. They assist in colonization, nutrient acquisition, immune evasion, and systemic spread. The structural and functional characteristics of the secreted virulence proteins have been shaped to assist S. aureus in thriving and disseminating effectively within the host environment and exploiting the host resources to its best benefit. With the aim of highlighting the importance of secreted virulence proteins in bacterial virulence, the present chapter provides a comprehensive account of the role of the major secreted proteins of S. aureus in orchestrating its virulence in the human host.
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Affiliation(s)
- Dileep Francis
- Department of Life Sciences, Kristu Jayanti College, Autonomous, Bengaluru, Karnataka, India.
| | - Anusha Bhairaddy
- Department of Life Sciences, Kristu Jayanti College, Autonomous, Bengaluru, Karnataka, India
| | - Atheene Joy
- Department of Life Sciences, Kristu Jayanti College, Autonomous, Bengaluru, Karnataka, India
| | | | - Ashik Francis
- Rajiv Gandhi Centre for Biotechnology, Trivandrum, Kerala, India
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3
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Yildirim F, Sudagidan M, Aydin A, Akyazi I, Bayrakal GM, Yavuz O, Gurel A. In Vivo Pathogenicity of Methicillin-Susceptible Staphylococcus aureus Strains Carrying Panton-Valentine Leukocidin Gene. Life (Basel) 2022; 12:2126. [PMID: 36556491 PMCID: PMC9780921 DOI: 10.3390/life12122126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/07/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Toxin-producing Staphylococcus aureus strains posing a potential risk for public health have long been a topic of scientific research. Effects of Panton-Valentine leukocidin (PVL) on tissue destruction mechanisms and activities of inflammatory cells were presented in animal models of pneumonia and skin infections induced by PVL-producing S. aureus strains. This study aimed to demonstrate the in vivo pathogenicity of PVL-producing S. aureus strains isolated from some foodstuffs, which can be a potential risk to public health. PVL-positive methicillin-susceptible S. aureus (MSSA) strains M1 and YF1B-b isolated from different foodstuffs and a PVL-positive MSSA strain HT480 (positive control) were administered to New Zealand rabbits. Blood samples were harvested three and six hours after the intratracheal inoculation. Lung tissue samples were collected for gross and microscopic exams and immunohistochemical (IHC) demonstration of IL-6, IL8, IL-10, and TNF-α expressions. Serum cytokine levels were also measured by ELISA. The strains isolated from lung tissue samples were confirmed by pulsed-field gel electrophoresis. The development of acute necrotising pneumonia and a significant elevation in IL-6, IL-8, IL-10, and TNF-α expressions demonstrated the significance of foodborne PVL-positive MSSA strains in public health for the first time.
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Affiliation(s)
- Funda Yildirim
- Department of Pathology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, Istanbul 34500, Turkey
| | - Mert Sudagidan
- Scientific and Technology Application and Research Center, Mehmet Akif Ersoy University, Burdur 15030, Turkey
| | - Ali Aydin
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, Istanbul 34500, Turkey
| | - Ibrahim Akyazi
- Department of Physiology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, Istanbul 34500, Turkey
| | - Gulay Merve Bayrakal
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, Istanbul 34500, Turkey
| | - Orhan Yavuz
- Scientific and Technology Application and Research Center, Mehmet Akif Ersoy University, Burdur 15030, Turkey
| | - Aydin Gurel
- Department of Pathology, Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa, Istanbul 34500, Turkey
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4
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Sannigrahi A, Chattopadhyay K. Pore formation by pore forming membrane proteins towards infections. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:79-111. [PMID: 35034727 DOI: 10.1016/bs.apcsb.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last 25 years, the biology of membrane proteins, including the PFPs-membranes interactions is seeking attention for the development of successful drug molecules against a number of infectious diseases. Pore forming toxins (PFTs), the largest family of PFPs are considered as a group of virulence factors produced in a large number of pathogenic systems which include streptococcus, pneumonia, Staphylococcus aureus, E. coli, Mycobacterium tuberculosis, group A and B streptococci, Corynebacterium diphtheria and many more. PFTs are generally utilized by the disease causing pathogens to disrupt the host first line of defense i.e. host cell membranes through pore formation strategy. Although, pore formation is the principal mode of action of the PFTs but they can have additional adverse effects on the hosts including immune evasion. Recently, structural investigation of different PFTs have imparted the molecular mechanistic insights into how PFTs get transformed from its inactive state to active toxic state. On the basis of their structural entity, PFTs have been classified in different types and their mode of actions alters in terms of pore formation and corresponding cellular toxicity. Although pathogen genome analysis can identify the probable PFTs depending upon their structural diversity, there are so many PFTs which utilize the local environmental conditions to generate their pore forming ability using a novel strategy which is known as "conformational switch" of a protein. This conformational switch is considered as characteristics of the phase shifting proteins which were often utilized by many pathogenic systems to protect them from the invaders through allosteric communication between distant regions of the protein. In this chapter, we discuss the structure function relationships of PFTs and how activity of PFTs varies with the change in the environmental conditions has been explored. Finally, we demonstrate these structural insights to develop therapeutic potential to treat the infections caused by multidrug resistant pathogens.
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Affiliation(s)
- Achinta Sannigrahi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka, India.
| | - Krishnananda Chattopadhyay
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
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5
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Zhang J, Conly J, McClure J, Wu K, Petri B, Barber D, Elsayed S, Armstrong G, Zhang K. A Murine Skin Infection Model Capable of Differentiating the Dermatopathology of Community-Associated MRSA Strain USA300 from Other MRSA Strains. Microorganisms 2021; 9:microorganisms9020287. [PMID: 33573328 PMCID: PMC7912111 DOI: 10.3390/microorganisms9020287] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/23/2021] [Accepted: 01/26/2021] [Indexed: 12/31/2022] Open
Abstract
USA300 is a predominant and highly virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain that is a leading cause of skin and soft tissue infections. We established a murine intradermal infection model capable of demonstrating dermatopathological differences between USA300 and other MRSA strains. In this model, USA300 induced dermonecrosis, uniformly presenting as extensive open lesions with a histologically documented profound inflammatory cell infiltrate extending below the subcutis. In contrast, USA400 and a colonizing control strain M92 caused only localized non-ulcerated skin infections associated with a mild focal inflammatory infiltrate. It was also determined that the dermonecrosis induced by USA300 was associated with significantly increased neutrophil recruitment, inhibition of an antibacterial response, and increased production of cytokines/chemokines associated with disease severity. These results suggest that induction of severe skin lesions by USA300 is related to over-activation of neutrophils, inhibition of host antibacterial responses, and selective alteration of host cytokine/chemokine profiles.
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Affiliation(s)
- Jack Zhang
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada; (J.Z.); (J.C.); (J.M.); (K.W.); (D.B.)
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
| | - John Conly
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada; (J.Z.); (J.C.); (J.M.); (K.W.); (D.B.)
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
- Department of Medicine, University of Calgary, Calgary, AB T2N4N1, Canada
- Centre for Antimicrobial Resistance, Alberta Health Services, Alberta Precision Laboratories, University of Calgary, Calgary, AB T2N4N1, Canada
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N4N1, Canada
| | - JoAnn McClure
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada; (J.Z.); (J.C.); (J.M.); (K.W.); (D.B.)
- Centre for Antimicrobial Resistance, Alberta Health Services, Alberta Precision Laboratories, University of Calgary, Calgary, AB T2N4N1, Canada
| | - Kaiyu Wu
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada; (J.Z.); (J.C.); (J.M.); (K.W.); (D.B.)
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
| | - Bjӧrn Petri
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N4N1, Canada
| | - Duane Barber
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada; (J.Z.); (J.C.); (J.M.); (K.W.); (D.B.)
| | - Sameer Elsayed
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
- Department of Medicine, University of Western Ontario, London, ON N6A5C1, Canada
| | - Glen Armstrong
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
| | - Kunyan Zhang
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada; (J.Z.); (J.C.); (J.M.); (K.W.); (D.B.)
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB T2N4N1, Canada; (B.P.); (S.E.); (G.A.)
- Department of Medicine, University of Calgary, Calgary, AB T2N4N1, Canada
- Centre for Antimicrobial Resistance, Alberta Health Services, Alberta Precision Laboratories, University of Calgary, Calgary, AB T2N4N1, Canada
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N4N1, Canada
- Correspondence: ; Tel.: +1-403-210-8484
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6
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Research Techniques Made Simple: Mouse Bacterial Skin Infection Models for Immunity Research. J Invest Dermatol 2020; 140:1488-1497.e1. [PMID: 32407714 DOI: 10.1016/j.jid.2020.04.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 01/11/2023]
Abstract
Bacterial skin infections are a major societal health burden and are increasingly difficult to treat owing to the emergence of antibiotic-resistant strains such as community-acquired methicillin-resistant Staphylococcus aureus. Understanding the immunologic mechanisms that provide durable protection against skin infections has the potential to guide the development of immunotherapies and vaccines to engage the host immune response to combat these antibiotic-resistant strains. To this end, mouse skin infection models allow researchers to examine host immunity by investigating the timing, inoculum, route of infection and the causative bacterial species in different wild-type mouse backgrounds as well as in knockout, transgenic, and other types of genetically engineered mouse strains. To recapitulate the various types of human skin infections, many different mouse models have been developed. For example, four models frequently used in dermatological research are based on the route of infection, including (i) subcutaneous infection models, (ii) intradermal infection models, (iii) wound infection models, and (iv) epicutaneous infection models. In this article, we will describe these skin infection models in detail along with their advantages and limitations. In addition, we will discuss how humanized mouse models such as the human skin xenograft on immunocompromised mice might be used in bacterial skin infection research.
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7
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Hoppe PA, Holzhauer S, Lala B, Bührer C, Gratopp A, Hanitsch LG, Humme D, Kieslich M, Kallinich T, Lau S, Leistner R, Niebank M, Pokrywka A, Ringe H, Schaper AS, Schröder JT, Schwarz C, Staab D, Stegemann MS, Thee S, Varnholt V, von Bernuth H, Weber-Carstens S, Wendt A, Krüger R. Severe infections of Panton-Valentine leukocidin positive Staphylococcus aureus in children. Medicine (Baltimore) 2019; 98:e17185. [PMID: 31567961 PMCID: PMC6756729 DOI: 10.1097/md.0000000000017185] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Infections caused by Panton-Valentine leukocidin-positive Staphylococcus aureus (PVL-SA) mostly present as recurrent skin abscesses and furunculosis. However, life-threatening infections (eg, necrotizing pneumonia, necrotizing fasciitis, and osteomyelitis) caused by PVL-SA have also been reported.We assessed the clinical phenotype, frequency, clinical implications (surgery, length of treatment in hospitals/intensive care units, and antibiotic treatments), and potential preventability of severe PVL-SA infections in children.Total, 75 children treated for PVL-SA infections in our in- and outpatient units from 2012 to 2017 were included in this retrospective study.Ten out of 75 children contracted severe infections (PVL-methicillin resistant S aureus n = 4) including necrotizing pneumonia (n = 4), necrotizing fasciitis (n = 2), pyomyositis (n = 2; including 1 patient who also had pneumonia), mastoiditis with cerebellitis (n = 1), preorbital cellulitis (n = 1), and recurrent deep furunculosis in an immunosuppressed patient (n = 1). Specific complications of PVL-SA infections were venous thrombosis (n = 2), sepsis (n = 5), respiratory failure (n = 5), and acute respiratory distress syndrome (n = 3). The median duration of hospital stay was 14 days (range 5-52 days). In 6 out of 10 patients a history suggestive for PVL-SA colonization in the patient or close family members before hospital admission was identified.PVL-SA causes severe to life-threatening infections requiring lengthy treatments in hospital in a substantial percentage of symptomatic PVL-SA colonized children. More than 50% of severe infections might be prevented by prompt testing for PVL-SA in individuals with a history of abscesses or furunculosis, followed by decolonization measures.
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Affiliation(s)
- Pia-Alice Hoppe
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | | | | | | | | | | | - Daniel Humme
- Department of Dermatology, Venerology and Allergy
| | | | | | - Susanne Lau
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | | | | | | | - Hannelore Ringe
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | | | | | - Carsten Schwarz
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | - Doris Staab
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | | | - Stephanie Thee
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | - Verena Varnholt
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | - Horst von Bernuth
- Department of Pediatric Pneumology, Immunology and Intensive Care
- Department of Immunology, Labor Berlin Charité-Vivantes GmbH
- Berlin-Brandenburg Center for Regenerative Therapies
| | - Steffen Weber-Carstens
- Department of Anesthesiology and Operative Intensive Care Medicine Campus Mitte and Campus-Virchow Klinikum, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Anke Wendt
- Department of Pediatric Pneumology, Immunology and Intensive Care
| | - Renate Krüger
- Department of Pediatric Pneumology, Immunology and Intensive Care
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8
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Young BC, Earle SG, Soeng S, Sar P, Kumar V, Hor S, Sar V, Bousfield R, Sanderson ND, Barker L, Stoesser N, Emary KR, Parry CM, Nickerson EK, Turner P, Bowden R, Crook DW, Wyllie DH, Day NP, Wilson DJ, Moore CE. Panton-Valentine leucocidin is the key determinant of Staphylococcus aureus pyomyositis in a bacterial GWAS. eLife 2019; 8:42486. [PMID: 30794157 PMCID: PMC6457891 DOI: 10.7554/elife.42486] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 02/21/2019] [Indexed: 02/07/2023] Open
Abstract
Pyomyositis is a severe bacterial infection of skeletal muscle, commonly affecting children in tropical regions, predominantly caused by Staphylococcus aureus. To understand the contribution of bacterial genomic factors to pyomyositis, we conducted a genome-wide association study of S. aureus cultured from 101 children with pyomyositis and 417 children with asymptomatic nasal carriage attending the Angkor Hospital for Children, Cambodia. We found a strong relationship between bacterial genetic variation and pyomyositis, with estimated heritability 63.8% (95% CI 49.2–78.4%). The presence of the Panton–Valentine leucocidin (PVL) locus increased the odds of pyomyositis 130-fold (p=10-17.9). The signal of association mapped both to the PVL-coding sequence and to the sequence immediately upstream. Together these regions explained over 99.9% of heritability (95% CI 93.5–100%). Our results establish staphylococcal pyomyositis, like tetanus and diphtheria, as critically dependent on a single toxin and demonstrate the potential for association studies to identify specific bacterial genes promoting severe human disease. Certain bacteria that normally live on the skin or in the nose without causing problems can sometimes lead to diseases elsewhere in the body. For example, the bacterium Staphylococcus aureus can cause blood infections or a severe and painful infection of the muscle called pyomyositis, which is very common in children who live in the tropics. Scientists believe that pyomyositis happens when S. aureus bacteria in the blood stream infect the muscles. Some strains of this bacteria are more likely to cause such infections, but why is unclear. One potential cause is a toxin produced by some S. aureus bacteria called Panton-Valentine leucocidin (PVL). So far, studies looking at whether PVL-producing bacteria are more likely to cause pyomyositis have had conflicting results. Now, Young et al. show that the gene for PVL is always present in S. aureus strains that cause pyomyosistis in Cambodian children, but is rarely found in S. aureus taken from the noses of their healthy counterparts. In the experiments, bacteria were collected from 101 children with pyomyositis and from the noses of 417 healthy children at the Angkor Hospital for Children in Cambodia over a 5-year period. The DNA in these bacteria were compared using very sensitive genetic techniques. The comparisons showed having the gene for PVL increased the odds of having pyomyositis 130-fold, showing that this one toxin likely accounts for much of the risk of developing this disease. If more studies confirm the link between PVL and pyomyositis, developing vaccines that block the gene for PVL might be one way to protect children in the tropics from developing this infection. Treating children with pyomyositis with antibiotics that reduce the production of the PVL toxin may also be helpful.
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Affiliation(s)
- Bernadette C Young
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.,NIHR Oxford Biomedical Research Centre, Infection Theme, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, United Kingdom
| | - Sarah G Earle
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Sona Soeng
- Cambodia Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia
| | - Poda Sar
- Cambodia Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia
| | - Varun Kumar
- Department of Pediatrics, East Tennessee State University Quillen College of Medicine, Johnson City, United States
| | - Songly Hor
- Cambodia Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia
| | - Vuthy Sar
- Cambodia Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia
| | - Rachel Bousfield
- Department of Infectious Diseases, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Nicholas D Sanderson
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Leanne Barker
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Nicole Stoesser
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.,Public Health England Academic Collaborating Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Katherine Rw Emary
- NIHR Oxford Biomedical Research Centre, Infection Theme, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, United Kingdom
| | - Christopher M Parry
- Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Emma K Nickerson
- Department of Infectious Diseases, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Paul Turner
- Cambodia Oxford Medical Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Rory Bowden
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Derrick W Crook
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.,NIHR Oxford Biomedical Research Centre, Infection Theme, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, United Kingdom.,Public Health England Academic Collaborating Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - David H Wyllie
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.,Public Health England Academic Collaborating Centre, John Radcliffe Hospital, Oxford, United Kingdom.,The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Nicholas Pj Day
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Daniel J Wilson
- Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.,Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.,Institute for Emerging Infections, Oxford Martin School, University of Oxford, Oxford, United Kingdom
| | - Catrin E Moore
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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9
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Subscapular Abscess Caused by Panton-Valentine Leukocidin-Positive Staphylococcus aureus: An Atypical Presentation. Case Rep Orthop 2018; 2018:8256428. [PMID: 29984024 PMCID: PMC6015668 DOI: 10.1155/2018/8256428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 04/29/2018] [Indexed: 11/17/2022] Open
Abstract
Subscapular abscess is an uncommon condition which requires early recognition followed by prompt surgical intervention. We present a case of spontaneous subscapular abscess following blunt trauma to the shoulder in a patient with a history of recurrent superficial soft tissue infections, in which Panton-Valentine leukocidin-producing S. aureus was identified as the infectious agent. This strain due to its virulence can lead to fatal infections in otherwise healthy individuals; therefore, a high index of suspicion is needed to investigate with an MRI to rule out abscess formation in a patient with acute shoulder girdle pain and negative joint aspirate. Urgent surgical intervention and targeted antimicrobial therapy against PVL-positive S. aureus in accordance with microbiologist yield good outcomes.
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10
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Angiotensin-converting enzyme enhances the oxidative response and bactericidal activity of neutrophils. Blood 2017; 130:328-339. [PMID: 28515091 DOI: 10.1182/blood-2016-11-752006] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 05/15/2017] [Indexed: 01/04/2023] Open
Abstract
Angiotensin-converting enzyme (ACE) inhibitors are widely used to reduce blood pressure. Here, we examined if an ACE is important for the antibacterial effectiveness of neutrophils. ACE knockout mice or mice treated with an ACE inhibitor were more susceptible to bacterial infection by methicillin-resistant Staphylococcus aureus (MRSA). In contrast, mice overexpressing ACE in neutrophils (NeuACE mice) have increased resistance to MRSA and better in vitro killing of MRSA, Pseudomonas aeruginosa, and Klebsiella pneumoniae ACE overexpression increased neutrophil production of reactive oxygen species (ROS) following MRSA challenge, an effect independent of the angiotensin II AT1 receptor. Specifically, as compared with wild-type (WT) mice, there was a marked increase of superoxide generation (>twofold, P < .0005) in NeuACE neutrophils following infection, whereas ACE knockout neutrophils decreased superoxide production. Analysis of membrane p47-phox and p67-phox indicates that ACE increases reduced NAD phosphate oxidase activity but does not increase expression of these subunits. Increased ROS generation mediates the enhanced bacterial resistance of NeuACE mice because the enhanced resistance is lost with DPI (an inhibitor of ROS production by flavoenzymes) inhibition. NeuACE granulocytes also have increased neutrophil extracellular trap formation and interleukin-1β release in response to MRSA. In a mouse model of chemotherapy-induced neutrophil depletion, transfusion of ACE-overexpressing neutrophils was superior to WT neutrophils in treating MRSA infection. These data indicate a previously unknown function of ACE in neutrophil antibacterial defenses and suggest caution in the treatment of certain individuals with ACE inhibitors. ACE overexpression in neutrophils may be useful in boosting the immune response to antibiotic-resistant bacterial infection.
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11
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Agarwal N, Aroor S, Saini P, Gupta A, Kaur N. Pyomyositis: Are We Missing the Diagnosis? Surg Infect (Larchmt) 2016; 17:615-21. [PMID: 27463090 DOI: 10.1089/sur.2015.191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Pyomyositis (PY) is a primary infection of the skeletal muscles, leading to inflammation of the muscle fibers followed by pus formation and even necrosis in late stages. Because of overlap in presentation of intermuscular abscess (IM) and PY, the exact incidence and severity of PY is under-appreciated. PATIENTS AND METHODS We conducted a prospective analytical study in a tertiary care center in North India from October 2011 to January 2013, recruiting patients with abscesses involving the chest wall, abdomen (parietal wall including back), and extremities. Subcutaneous, hepatic, intra-abdominal abscess, and secondary abscesses were excluded. Primary PY was defined as a primary infection of skeletal muscle without any foci from adjacent skin, soft tissue, or bone. Clinical, radiologic, pathologic, and operative findings suggested diagnosis; loss of striations and lymphocytic infiltration in the muscle fibers was confirmatory. The chief outcome variables were death and length of hospital stay. RESULTS Thirty patients with a mean age of 29.5 y (IM: 29.7 ± 16.7, PY: 25.28 ± 17.6) were classified as IM (18/30, 60%) or PY (12/30, 40%). Most PY occurred in the lower limb (41.7% had multi-site involvement); most had a history of trauma or immunocompromised state. Fever, tachycardia, tachypnea, hypotension, pallor, and hyperesthesia were significantly higher (p < 0.05) in PY. Mean Sequential Organ Failure Assessment (SOFA) score was 0.33 for IM, 2.5 for PY. Staphylococcus aureus was predominant in both groups; however, all four patients with methicillin-resistant S. aureus (MRSA) were in the PY group. Both deaths also occurred in the PY group. The mean duration of hospital stay was 3.22 ± 1.11 d for IM and 10.27 ± 2.32 d for PY patients (p = 0.03). CONCLUSION PY is a specific and potentially fatal infection, which is common in our country and must be differentiated from IM. A high index of suspicion and early institution of specific antibiotics followed by operation is therapeutic.
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Affiliation(s)
- Nitin Agarwal
- Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India
| | - Shashank Aroor
- Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India
| | - Pradeep Saini
- Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India
| | - Arun Gupta
- Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India
| | - Navneet Kaur
- Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India
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Tseng CW, Biancotti JC, Berg BL, Gate D, Kolar SL, Müller S, Rodriguez MD, Rezai-Zadeh K, Fan X, Beenhouwer DO, Town T, Liu GY. Increased Susceptibility of Humanized NSG Mice to Panton-Valentine Leukocidin and Staphylococcus aureus Skin Infection. PLoS Pathog 2015; 11:e1005292. [PMID: 26618545 PMCID: PMC4664407 DOI: 10.1371/journal.ppat.1005292] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 10/30/2015] [Indexed: 12/23/2022] Open
Abstract
Staphylococcus aureus is a leading cause of skin and soft-tissue infections worldwide. Mice are the most commonly used animals for modeling human staphylococcal infections. However a supra-physiologic S. aureus inoculum is required to establish gross murine skin pathology. Moreover, many staphylococcal factors, including Panton-Valentine leukocidin (PVL) elaborated by community-associated methicillin-resistant S. aureus (CA-MRSA), exhibit selective human tropism and cannot be adequately studied in mice. To overcome these deficiencies, we investigated S. aureus infection in non-obese diabetic (NOD)/severe combined immune deficiency (SCID)/IL2rγnull (NSG) mice engrafted with human CD34+ umbilical cord blood cells. These “humanized” NSG mice require one to two log lower inoculum to induce consistent skin lesions compared with control mice, and exhibit larger cutaneous lesions upon infection with PVL+ versus isogenic PVL-S. aureus. Neutrophils appear important for PVL pathology as adoptive transfer of human neutrophils alone to NSG mice was sufficient to induce dermonecrosis following challenge with PVL+S. aureus but not PVL-S. aureus. PMX53, a human C5aR inhibitor, blocked PVL-induced cellular cytotoxicity in vitro and reduced the size difference of lesions induced by the PVL+ and PVL-S. aureus, but PMX53 also reduced recruitment of neutrophils and exacerbated the infection. Overall, our findings establish humanized mice as an important translational tool for the study of S. aureus infection and provide strong evidence that PVL is a human virulence factor. S. aureus infection has emerged in the past decade as a major burden to public health and is responsible for a surge in preclinical research. Mice are the most commonly studied animals for modeling of human S. aureus infection. However, it is increasingly evident that available murine models poorly mimic human S. aureus disease. Routinely, a supra-physiologic inoculum is required to establish soft-tissue pathology. Additionally, many S. aureus factors exhibit unique human tropism and cannot be adequately investigated in rodents. Here we investigated S. aureus infection in NSG mice engrafted with human umbilical CD34+ cells. We showed that a one to two log lower infectious inoculum of S. aureus establishes consistent skin lesions in humanized NSG mice. This inoculum is comparable to published inocula required to induce infection in humans. In addition, we showed that Panton-Valentine Leucocidin, a human tropic factor secreted by S. aureus, contributes to the development of dermonecrosis in the humanized mice, and its interaction with human neutrophils and human C5a receptor appears to be important for immunopathology. Overall our study suggests that humanized mice are an improved tool for modeling of human S. aureus infection.
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Affiliation(s)
- Ching Wen Tseng
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail: (GYL); (CWT)
| | - Juan Carlos Biancotti
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Bethany L. Berg
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - David Gate
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Stacey L. Kolar
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Sabrina Müller
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Maria D. Rodriguez
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Kavon Rezai-Zadeh
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Xuemo Fan
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - David O. Beenhouwer
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Terrence Town
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - George Y. Liu
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail: (GYL); (CWT)
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Melehani JH, James DBA, DuMont AL, Torres VJ, Duncan JA. Staphylococcus aureus Leukocidin A/B (LukAB) Kills Human Monocytes via Host NLRP3 and ASC when Extracellular, but Not Intracellular. PLoS Pathog 2015; 11:e1004970. [PMID: 26069969 PMCID: PMC4466499 DOI: 10.1371/journal.ppat.1004970] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 05/22/2015] [Indexed: 12/27/2022] Open
Abstract
Staphylococcus aureus infections are a growing health burden worldwide, and paramount to this bacterium’s pathogenesis is the production of virulence factors, including pore-forming leukotoxins. Leukocidin A/B (LukAB) is a recently discovered toxin that kills primary human phagocytes, though the underlying mechanism of cell death is not understood. We demonstrate here that LukAB is a major contributor to the death of human monocytes. Using a variety of in vitro and ex vivo intoxication and infection models, we found that LukAB activates Caspase 1, promotes IL-1β secretion and induces necrosis in human monocytes. Using THP1 cells as a model for human monocytes, we found that the inflammasome components NLRP3 and ASC are required for LukAB-mediated IL-1β secretion and necrotic cell death. S. aureus was shown to kill human monocytes in a LukAB dependent manner under both extracellular and intracellular ex vivo infection models. Although LukAB-mediated killing of THP1 monocytes from extracellular S. aureus requires ASC, NLRP3 and the LukAB-receptor CD11b, LukAB-mediated killing from phagocytosed S. aureus is independent of ASC or NLRP3, but dependent on CD11b. Altogether, this study provides insight into the nature of LukAB-mediated killing of human monocytes. The discovery that S. aureus LukAB provokes differential host responses in a manner dependent on the cellular contact site is critical for the development of anti-infective/anti-inflammatory therapies that target the NLRP3 inflammasome. Staphylococcus aureus infections are becoming increasingly common, aggressive, and difficult to manage clinically. S. aureus produces a number of pore-forming toxins that target and kill immune cells. In this study, we demonstrate that LukAB is primarily responsible for S. aureus-mediated targeting and killing of human monocytes. We show that the NLRP3-ASC inflammasome, a sensor of cell membrane damage and trigger of inflammation, is critical for this response. S. aureus uses LukAB to kill immune cells both through external interactions (LukAB on the cell surface) and through internal interactions (LukAB secretion after S. aureus is engulfed by the immune cell). Interestingly, we show that the mechanism by which LukAB kills immune cells in these two settings differs. This is the first report of a S. aureus toxin manipulating unique immune signaling pathways depending on the cellular site of contact. Understanding the multitude of ways by which S. aureus evades the immune response is critical for our ability to treat infections with this pathogen.
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Affiliation(s)
- Jason H. Melehani
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - David B. A. James
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Ashley L. DuMont
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (VJT); (JAD)
| | - Joseph A. Duncan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Medicine, Division of Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail: (VJT); (JAD)
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14
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The bicomponent pore-forming leucocidins of Staphylococcus aureus. Microbiol Mol Biol Rev 2015; 78:199-230. [PMID: 24847020 DOI: 10.1128/mmbr.00055-13] [Citation(s) in RCA: 192] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ability to produce water-soluble proteins with the capacity to oligomerize and form pores within cellular lipid bilayers is a trait conserved among nearly all forms of life, including humans, single-celled eukaryotes, and numerous bacterial species. In bacteria, some of the most notable pore-forming molecules are protein toxins that interact with mammalian cell membranes to promote lysis, deliver effectors, and modulate cellular homeostasis. Of the bacterial species capable of producing pore-forming toxic molecules, the Gram-positive pathogen Staphylococcus aureus is one of the most notorious. S. aureus can produce seven different pore-forming protein toxins, all of which are believed to play a unique role in promoting the ability of the organism to cause disease in humans and other mammals. The most diverse of these pore-forming toxins, in terms of both functional activity and global representation within S. aureus clinical isolates, are the bicomponent leucocidins. From the first description of their activity on host immune cells over 100 years ago to the detailed investigations of their biochemical function today, the leucocidins remain at the forefront of S. aureus pathogenesis research initiatives. Study of their mode of action is of immediate interest in the realm of therapeutic agent design as well as for studies of bacterial pathogenesis. This review provides an updated perspective on our understanding of the S. aureus leucocidins and their function, specificity, and potential as therapeutic targets.
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15
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Bar-Gal GK, Blum S, Hadas L, Ehricht R, Monecke S, Leitner G. Host-specificity of Staphylococcus aureus causing intramammary infections in dairy animals assessed by genotyping and virulence genes. Vet Microbiol 2015; 176:143-54. [DOI: 10.1016/j.vetmic.2015.01.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/31/2014] [Accepted: 01/07/2015] [Indexed: 02/04/2023]
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16
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Gillet-Vittori L, Afanetti M, Dupont A, Gondon E, Dupont D. [Life-threatening Panton-Valentine leukocidin-associated staphylococcal infections in children. A broad spectrum of clinical presentations]. Arch Pediatr 2014; 21:1220-5. [PMID: 25284731 DOI: 10.1016/j.arcped.2014.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 05/08/2014] [Accepted: 08/01/2014] [Indexed: 11/26/2022]
Abstract
Panton-Valentine leukocidin (PVL) is a major toxic virulence factor secreted by community-acquired methicillin-sensitive or methicillin-resistant Staphylococcus aureus (SA). SA-PVL can be responsible for life-threatening infections in healthy children with a wide spectrum of clinical presentations involving lung, skin, and soft tissues or bones and joints. PVL production should always be considered in severe SA infections. The pediatric medicine community remains poorly informed regarding the therapeutic management of this infection, which should be early and aggressive. Intravenous empiric antibiotics against SA and its toxins must be given with early and sometimes iterative surgical procedures to drain abscesses and to stop bacterial proliferation and necrosis in the tissues. Here, we report the cases of three patients admitted for SA-PVL infections to the pediatric intensive care unit. Initial clinical presentation in the three patients was multifocal osteomyelitis associated with necrotizing pneumonia; severe skin infection with septic shock; and non-necrotic pneumonia with pleural and pericardial effusion. Appropriate treatments resulted in a good outcome in all cases. Following these illustrations, we describe a number of practical key points in the optimal medical and surgical management of severe SA-PVL infections, with a review of the literature.
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Affiliation(s)
- L Gillet-Vittori
- Service de réanimation pédiatrique, hôpitaux pédiatriques, CHU Lenval, 57, avenue de la Californie, 06000 Nice, France.
| | - M Afanetti
- Service de réanimation pédiatrique, hôpitaux pédiatriques, CHU Lenval, 57, avenue de la Californie, 06000 Nice, France
| | - A Dupont
- Service de réanimation pédiatrique, hôpitaux pédiatriques, CHU Lenval, 57, avenue de la Californie, 06000 Nice, France
| | - E Gondon
- Service de réanimation pédiatrique, hôpitaux pédiatriques, CHU Lenval, 57, avenue de la Californie, 06000 Nice, France
| | - D Dupont
- Service de réanimation pédiatrique, hôpitaux pédiatriques, CHU Lenval, 57, avenue de la Californie, 06000 Nice, France
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17
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De Waele JJ. Management of necrotizing skin and soft tissue infections. Expert Rev Anti Infect Ther 2014; 10:805-14. [PMID: 22943403 DOI: 10.1586/eri.12.64] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Although rare, necrotizing skin and soft tissue infections can be devastating infections that are difficult to diagnose and challenging to manage. Clinical presentation is often insidious, and a low index of suspicion is critical. Various diagnostic tools, such as scoring systems or imaging techniques, have been introduced, but none is convincingly superior to sound clinical judgment. Early diagnosis allows early adequate therapy that includes antibiotic therapy, critical care support, specific interventions such as intravenous immunoglobulin in selected patients and, most importantly, early source control. Empirical antibiotic therapy should cover a broad range of both Gram-negative and Gram-positive aerobic and anaerobic microorganisms, and clindamycin is recommended when group A Streptococcus is a suspected pathogen.
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Affiliation(s)
- Jan J De Waele
- Department of Critical Care Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
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18
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Figueiredo AMS, Ferreira FA. The multifaceted resources and microevolution of the successful human and animal pathogen methicillin-resistant Staphylococcus aureus. Mem Inst Oswaldo Cruz 2014; 109:265-78. [PMID: 24789555 PMCID: PMC4131778 DOI: 10.1590/0074-0276140016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/12/2014] [Indexed: 11/22/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important bacterial pathogens based on its incidence and the severity of its associated infections. In addition, severe MRSA infections can occur in hospitalised patients or healthy individuals from the community. Studies have shown the infiltration of MRSA isolates of community origin into hospitals and variants of hospital-associated MRSA have caused infections in the community. These rapid epidemiological changes represent a challenge for the molecular characterisation of such bacteria as a hospital or community-acquired pathogen. To efficiently control the spread of MRSA, it is important to promptly detect the mecA gene, which is the determinant of methicillin resistance, using a polymerase chain reaction-based test or other rapidly and accurate methods that detect the mecA product penicillin-binding protein (PBP)2a or PBP2'. The recent emergence of MRSA isolates that harbour a mecA allotype, i.e., the mecC gene, infecting animals and humans has raised an additional and significant issue regarding MRSA laboratory detection. Antimicrobial drugs for MRSA therapy are becoming depleted and vancomycin is still the main choice in many cases. In this review, we present an overview of MRSA infections in community and healthcare settings with focus on recent changes in the global epidemiology, with special reference to the MRSA picture in Brazil.
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Affiliation(s)
- Agnes Marie Sá Figueiredo
- Departamento de Microbiologia Médica , Instituto de Microbiologia Paulo de
Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , RJ ,
Brasil
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19
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Poojary NS, Ramlal S, Urs RM, Sripathy MH, Batra HV. Application of monoclonal antibodies generated against Panton-Valentine Leukocidin (PVL-S) toxin for specific identification of community acquired methicillin resistance Staphylococcus aureus. Microbiol Res 2014; 169:924-30. [PMID: 24935729 DOI: 10.1016/j.micres.2014.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 05/05/2014] [Accepted: 05/09/2014] [Indexed: 10/25/2022]
Abstract
Panton-Valentine Leukocidin (PVL) produced by community acquired methicillin Staphylococcus aureus (CA-MRSA) involved in skin and soft-tissue infections and necrotizing pneumonia comprised of two fractions, namely PVL S and PVL F. In the present study, three monoclonal antibodies designated as MAb1, MAb9 and MAb10 were generated against recombinant PVL-S (35kDa) protein of S. aureus. All the three MAbs specifically reacted to confirm PVL-S positive strains of S. aureus recovered from clinical samples in Western blot analysis. Similarly all the three MAbs did not show any binding to other tested 14 different pathogenic bacteria belonging to other genera and species in Western blot analysis. Furthermore, a simple dot-ELISA method was standardized for the identification of PVL-S toxin containing S. aureus strains. Initially in dot-ELISA, Protein A (Spa) of S. aureus posed background noise problems due to the non-specific binding of antibodies resulting in false positive reactions. With the addition of 10mM diethylpyrocarbonate (DEPC) along with 5% milk in PBS in the blocking step prevented this non-specific binding of Spa to mouse anti-PVL monoclonal antibodies in dot-ELISA. Once standardized, this simple dot-ELISA was evaluated with nine PVL positive strains recovered from food, environmental and clinical samples and the results were compared with PCR assay for the presence of PVL toxin genes and also with Western blot analysis. A 100% correlation was found between dot-ELISA, PCR assay and Western blot analysis. Collectively our results suggest the newly developed simple dot-ELISA system can be of immense help in providing, rapid detection of the PVL toxin containing S. aureus strains at a relatively low cost and will be a valuable tool for the reliable identification of CA-MRSA.
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Affiliation(s)
- Niveditha Sundar Poojary
- Division of Microbiology, Defence Food Research Laboratory, Siddartha Nagar, Mysore 570011, Karnataka, India.
| | - Shylaja Ramlal
- Division of Microbiology, Defence Food Research Laboratory, Siddartha Nagar, Mysore 570011, Karnataka, India.
| | - Radhika Madan Urs
- Division of Microbiology, Defence Food Research Laboratory, Siddartha Nagar, Mysore 570011, Karnataka, India.
| | | | - Harsh Vardhan Batra
- Division of Microbiology, Defence Food Research Laboratory, Siddartha Nagar, Mysore 570011, Karnataka, India.
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20
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Residues essential for Panton-Valentine leukocidin S component binding to its cell receptor suggest both plasticity and adaptability in its interaction surface. PLoS One 2014; 9:e92094. [PMID: 24643034 PMCID: PMC3958440 DOI: 10.1371/journal.pone.0092094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 02/18/2014] [Indexed: 01/01/2023] Open
Abstract
Panton-Valentine leukocidin (PVL), a bicomponent staphylococcal leukotoxin, is involved in the poor prognosis of necrotizing pneumonia. The present study aimed to elucidate the binding mechanism of PVL and in particular its cell-binding domain. The class S component of PVL, LukS-PV, is known to ensure cell targeting and exhibits the highest affinity for the neutrophil membrane (Kd∼10−10 M) compared to the class F component of PVL, LukF-PV (Kd∼10−9 M). Alanine scanning mutagenesis was used to identify the residues involved in LukS-PV binding to the neutrophil surface. Nineteen single alanine mutations were performed in the rim domain previously described as implicated in cell membrane interactions. Positions were chosen in order to replace polar or exposed charged residues and according to conservation between leukotoxin class S components. Characterization studies enabled to identify a cluster of residues essential for LukS-PV binding, localized on two loops of the rim domain. The mutations R73A, Y184A, T244A, H245A and Y250A led to dramatically reduced binding affinities for both human leukocytes and undifferentiated U937 cells expressing the C5a receptor. The three-dimensional structure of five of the mutants was determined using X-ray crystallography. Structure analysis identified residues Y184 and Y250 as crucial in providing structural flexibility in the receptor-binding domain of LukS-PV.
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21
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Aman MJ, Adhikari RP. Staphylococcal bicomponent pore-forming toxins: targets for prophylaxis and immunotherapy. Toxins (Basel) 2014; 6:950-72. [PMID: 24599233 PMCID: PMC3968370 DOI: 10.3390/toxins6030950] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/22/2014] [Accepted: 02/26/2014] [Indexed: 01/09/2023] Open
Abstract
Staphylococccus aureus represents one of the most challenging human pathogens as well as a common colonizer of human skin and mucosal surfaces. S. aureus causes a wide range of diseases from skin and soft tissue infection (SSTI) to debilitating and life-threatening conditions such as osteomyelitis, endocarditis, and necrotizing pneumonia. The range of diseases reflects the remarkable diversity of the virulence factors produced by this pathogen, including surface antigens involved in the establishment of infection and a large number of toxins that mediate a vast array of cellular responses. The staphylococcal toxins are generally believed to have evolved to disarm the innate immune system, the first line of defense against this pathogen. This review focuses on recent advances on elucidating the biological functions of S. aureus bicomponent pore-forming toxins (BCPFTs) and their utility as targets for preventive and therapeutic intervention. These toxins are cytolytic to a variety of immune cells, primarily neutrophils, as well as cells with a critical barrier function. The lytic activity of BCPFTs towards immune cells implies a critical role in immune evasion, and a number of epidemiological studies and animal experiments relate these toxins to clinical disease, particularly SSTI and necrotizing pneumonia. Antibody-mediated neutralization of this lytic activity may provide a strategy for development of toxoid-based vaccines or immunotherapeutics for prevention or mitigation of clinical diseases. However, certain BCPFTs have been proposed to act as danger signals that may alert the immune system through an inflammatory response. The utility of a neutralizing vaccination strategy must be weighed against such immune-activating potential.
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Affiliation(s)
- M Javad Aman
- Integrated BioTherapeutics Inc., 21 Firstfield Rd., Gaithersburg, MD 20878, USA.
| | - Rajan P Adhikari
- Integrated BioTherapeutics Inc., 21 Firstfield Rd., Gaithersburg, MD 20878, USA.
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22
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Chronisch rezidivierende Infektionen der Haut und Weichgewebe durch Staphylococcus aureus. Hautarzt 2014; 65:15-25. [DOI: 10.1007/s00105-013-2636-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zaidi T, Zaidi T, Yoong P, Pier GB. Staphylococcus aureus corneal infections: effect of the Panton-Valentine leukocidin (PVL) and antibody to PVL on virulence and pathology. Invest Ophthalmol Vis Sci 2013; 54:4430-8. [PMID: 23737477 DOI: 10.1167/iovs.13-11701] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
PURPOSE Community-associated methicillin-resistant Staphylococcus aureus strains expressing Panton-Valentine leukocidin (PVL) are associated with severe skin and soft tissue infections, necrotizing pneumonia, and eye infections. We determined PVL's toxicity on infected mouse and cultured human corneal epithelial cells and the role of PVL and antibody to PVL in pathogenesis of murine keratitis. METHODS Cytotoxicity on corneas and corneal epithelial cells was evaluated by LDH assays. Scratched corneas of female A/J mice were inoculated with approximately 10⁷ CFU/eye of either WT S. aureus, isogenic ΔPVL, or strains overproducing PVL. Antibodies to PVL or control sera were topically applied to infected corneas 0, 24, and 32 hours postinfection, corneas scored for pathology and tissue levels of S. aureus were determined. RESULTS PVL expression augmented the cytotoxicity of S. aureus on infected mouse corneas and human cultured corneal epithelial cells. Variable effects on leukocyte recruitment, pathogenesis, and immunity were obtained in the in vivo studies. Inactivation of PVL in USA300 strains caused reduced pathology and bacterial counts. Results were variable when comparing WT and ΔPVL USA400 strains, while USA400 strains overproducing PVL caused increased bacterial burdens. Topical treatment with polyclonal antibody to PVL yielded significant reductions in corneal pathology and bacterial CFU in corneas infected with USA300 strains, whereas effects were inconsistent in eyes infected with USA400 strains. CONCLUSIONS PVL enhanced the virulence of a subset of MRSA strains in a keratitis model. Coupled with a variable effect of antibody treatment, it appears that PVL plays an inconsistent role in pathogenesis and immunity to S. aureus corneal infection.
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Affiliation(s)
- Tanweer Zaidi
- Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Los FCO, Randis TM, Aroian RV, Ratner AJ. Role of pore-forming toxins in bacterial infectious diseases. Microbiol Mol Biol Rev 2013; 77:173-207. [PMID: 23699254 PMCID: PMC3668673 DOI: 10.1128/mmbr.00052-12] [Citation(s) in RCA: 299] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.
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Affiliation(s)
| | - Tara M. Randis
- Department of Pediatrics, Columbia University, New York, New York, USA
| | - Raffi V. Aroian
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, USA
| | - Adam J. Ratner
- Department of Pediatrics, Columbia University, New York, New York, USA
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Sharma-Kuinkel BK, Zhang Y, Yan Q, Ahn SH, Fowler VG. Host gene expression profiling and in vivo cytokine studies to characterize the role of linezolid and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA) murine sepsis model. PLoS One 2013; 8:e60463. [PMID: 23565251 PMCID: PMC3614971 DOI: 10.1371/journal.pone.0060463] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/26/2013] [Indexed: 01/11/2023] Open
Abstract
Linezolid (L), a potent antibiotic for Methicillin Resistant Staphylococcus aureus (MRSA), inhibits bacterial protein synthesis. By contrast, vancomycin (V) is a cell wall active agent. Here, we used a murine sepsis model to test the hypothesis that L treatment is associated with differences in bacterial and host characteristics as compared to V. Mice were injected with S. aureus USA300, and then intravenously treated with 25 mg/kg of either L or V at 2 hours post infection (hpi). In vivo alpha-hemolysin production was reduced in both L and V-treated mice compared to untreated mice but the reduction did not reach the statistical significance [P = 0.12 for L; P = 0.70 for V). PVL was significantly reduced in L-treated mice compared to untreated mice (P = 0.02). However the reduction of in vivo PVL did not reach the statistical significance in V- treated mice compared to untreated mice (P = 0.27). Both antibiotics significantly reduced IL-1β production [P = 0.001 for L; P = 0.006 for V]. IL-6 was significantly reduced with L but not V antibiotic treatment [P<0.001 for L; P = 0.11 for V]. Neither treatment significantly reduced production of TNF-α. Whole-blood gene expression profiling showed no significant effect of L and V on uninfected mice. In S. aureus-infected mice, L altered the expression of a greater number of genes than V (95 vs. 42; P = 0.001). Pathway analysis for the differentially expressed genes identified toll-like receptor signaling pathway to be common to each S. aureus-infected comparison. Expression of immunomodulatory genes like Cxcl9, Cxcl10, Il1r2, Cd14 and Nfkbia was different among the treatment groups. Glycerolipid metabolism pathway was uniquely associated with L treatment in S. aureus infection. This study demonstrates that, as compared to V, treatment with L is associated with reduced levels of toxin production, differences in host inflammatory response, and distinct host gene expression characteristics in MRSA sepsis.
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Affiliation(s)
- Batu K. Sharma-Kuinkel
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail: (BKSK); (SHA)
| | - Yurong Zhang
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Qin Yan
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sun Hee Ahn
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail: (BKSK); (SHA)
| | - Vance G. Fowler
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Clinical Research Institute, Durham, North Carolina, United States of America
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Grumann D, Nübel U, Bröker BM. Staphylococcus aureus toxins--their functions and genetics. INFECTION GENETICS AND EVOLUTION 2013; 21:583-92. [PMID: 23541411 DOI: 10.1016/j.meegid.2013.03.013] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/07/2013] [Accepted: 03/09/2013] [Indexed: 02/07/2023]
Abstract
The outcome of encounters between Staphylococcus (S.) aureus and its human host ranges from life-threatening infection through allergic reactions to symptom-free colonization. The pan-genome of this bacterial species encodes numerous toxins, known or strongly suspected to cause specific diseases or symptoms. Three toxin families are in the focus of this review, namely (i) pore-forming toxins, (ii) exfoliative toxins and (iii) superantigens. The majority of toxin-encoding genes are located on mobile genetic elements (MGEs), resulting in a pronounced heterogeneity in the endowment with toxin genes of individual S. aureus strains. Recent population genomic analysis have provided a framework for an improved understanding of the temporal and spatial scales of the motility of MGEs and their associated toxin genes. The distribution of toxin genes among clonal lineages within the species S. aureus is not random, and phylogenetic (sub-)lineages within clonal complexes feature characteristic toxin signatures. When studying pathogenesis, this lineage association, which is caused by the clonal nature of S. aureus makes it difficult to discriminate effects of specific toxins from contributions of the genetic background and/or other associated genetic factors.
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Affiliation(s)
- Dorothee Grumann
- Institute of Immunology and Transfusion Medicine, University of Greifswald, 17487 Greifswald, Germany
| | | | - Barbara M Bröker
- Institute of Immunology and Transfusion Medicine, University of Greifswald, 17487 Greifswald, Germany.
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Iwanaga N, Fukuda Y, Nakamura S, Imamura Y, Miyazaki T, Izumikawa K, Kakeya H, Yanagihara K, Soda H, Tashiro T, Kohno S. Necrotizing pneumonia due to femoral osteomyelitis caused by community-acquired methicillin-resistant Staphylococcus aureus. Intern Med 2013; 52:1531-6. [PMID: 23812205 DOI: 10.2169/internalmedicine.52.9561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A chest X-ray of a young healthy African-American man with acute respiratory failure revealed bilateral multiple nodular shadows in the lungs, while community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was detected in blood and sputum cultures. Magnetic resonance imaging showed osteomyelitis of the left thigh, and computed tomography revealed bilateral cavitary lesions in the chest, indicating necrotizing pneumonia with pulmonary embolism caused by osteomyelitis as a result of infection with CA-MRSA. CA-MRSA should be suspected as a causative agent of severe community-acquired pneumonia, even in Japan, among patients who belong to communities at high risk of CA-MRSA infection.
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Affiliation(s)
- Naoki Iwanaga
- Division of Respiratory Medicine, Sasebo City General Hospital, Japan
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Ceftobiprole efficacy in vitro against Panton-Valentine leukocidin production and in vivo against community-associated methicillin-resistant Staphylococcus aureus osteomyelitis in rabbits. Antimicrob Agents Chemother 2012; 56:6291-7. [PMID: 23027197 DOI: 10.1128/aac.00926-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) can cause osteomyelitis with severe sepsis and/or local complications in which a Panton-Valentine leukocidin (PVL) role is suspected. In vitro sub-MIC antibiotic effects on growth and PVL production by 11 PVL(+) MRSA strains, including the major CA-MRSA clones (USA300, including the LAC strain; USA400; and USA1000), and 11 PVL(+) methicillin-susceptible S. aureus (MSSA) strains were tested in microplate culture. Time-kill analyses with ceftobiprole at its MIC were also run with LAC. Efficacies of ceftobiprole (40 mg/kg of body weight subcutaneously [s.c.] four times a day [q.i.d.]) or vancomycin (60 mg/kg intramuscularly [i.m.] twice a day [b.i.d.]) alone or combined with rifampin (10 mg/kg b.i.d.) against rabbit CA-MRSA osteomyelitis, induced by tibial injection of 3.4 × 10(7) CFU of LAC, were compared. Treatment, started 14 days postinoculation, lasted 14 days. In vitro, 6/11 strains cultured with sub-MICs of ceftobiprole produced 1.6- to 4.8-fold more PVL than did the controls, with no link to specific clones. Rifampin decreased PVL production by all tested strains. In time-kill analyses at the LAC MIC (0.75 mg/liter), PVL production rose transiently at 6 and 8 h and then declined 2-fold at 16 h, concomitant with a 2-log(10)-CFU-count decrease. In vivo, the mean log(10) CFU/g of bone for ceftobiprole (1.44 ± 0.40) was significantly lower than that for vancomycin (2.37 ± 1.22) (P = 0.034), with 7/10 versus 5/11 bones sterilized, respectively. Combination with rifampin enhanced ceftobiprole (1.16 ± 0.04 CFU/g of bone [P = 0.056], 11/11 sterile bones) and vancomycin (1.23 ± 0.06 CFU/g [P = 0.011], 11/11 sterile bones) efficacies. Ceftobiprole bactericidal activity and the rifampin anti-PVL effect could play a role in these findings, which should be of interest for treating CA-MRSA osteomyelitis.
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Kyme P, Thoennissen NH, Tseng CW, Thoennissen GB, Wolf AJ, Shimada K, Krug UO, Lee K, Müller-Tidow C, Berdel WE, Hardy WD, Gombart AF, Koeffler HP, Liu GY. C/EBPε mediates nicotinamide-enhanced clearance of Staphylococcus aureus in mice. J Clin Invest 2012; 122:3316-29. [PMID: 22922257 DOI: 10.1172/jci62070] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 07/05/2012] [Indexed: 02/06/2023] Open
Abstract
The myeloid-specific transcription factor, CCAAT/enhancer-binding protein ε (C/EBPε) is a critical mediator of myelopoiesis. Mutation of this gene is responsible for neutrophil-specific granule deficiency in humans, a condition that confers susceptibility to Staphylococcus aureus infection. We found that C/EBPε-deficient mice are severely affected by infection with S. aureus, and C/EBPε deficiency in neutrophils contributes to the infectious phenotype. Conversely, exposure to the epigenetic modulator nicotinamide (vitamin B3) increased expression of C/EBPε in WT myeloid cells. Further, nicotinamide increased the activity of C/EBPε and select downstream antimicrobial targets, particularly in neutrophils. In a systemic murine infection model as well as in murine and human peripheral blood, nicotinamide enhanced killing of S. aureus by up to 1,000 fold but had no effect when administered to either C/EBPε-deficient mice or mice depleted of neutrophils. Nicotinamide was efficacious in both prophylactic and therapeutic settings. Our findings suggest that C/EBPε is an important target to boost killing of bacteria by the innate immune system.
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Affiliation(s)
- Pierre Kyme
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
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Tseng CW, Kyme PA, Arruda A, Ramanujan VK, Tawackoli W, Liu GY. Innate immune dysfunctions in aged mice facilitate the systemic dissemination of methicillin-resistant S. aureus. PLoS One 2012; 7:e41454. [PMID: 22844481 PMCID: PMC3406035 DOI: 10.1371/journal.pone.0041454] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 06/26/2012] [Indexed: 12/27/2022] Open
Abstract
Elderly humans show increased susceptibility to invasive staphylococcal disease after skin and soft tissue infection. However, it is not understood how host immunity changes with aging, and how that predisposes to invasive disease. In a model of severe skin infection, we showed that aged mice (16- to 20-month-old) exhibit dramatic bacterial dissemination compared with young adult mice (2-month-old). Bacterial dissemination was associated with significant reductions of CXCL1 (KC), polymorphonuclear cells (PMNs), and extracellular DNA traps (NETs) at the infection site. PMNs and primary skin fibroblasts isolated from aged mice showed decreased secretion of CXCL2 (MIP-2) and KC in response to MRSA, and in vitro analyses of mitochondrial functions revealed that the mitochondrial electron transport chain complex I plays a significant role in induction of chemokines in the cells isolated from young but not old mice. Additionally, PMNs isolated from aged mice have reduced ability to form NETs and to kill MRSA. Expression of nuclease by S. aureus led to increased bacterial systemic dissemination in young but not old mice, suggesting that defective NETs formation in elderly mice permitted nuclease and non-nuclease expressing S. aureus to disseminate equally well. Overall, these findings suggest that gross impairment of both skin barrier function and innate immunity contributes to the propensity for MRSA to disseminate in aged mice. Furthermore, the study indicates that contribution of bacterial factors to pathogenicity may vary with host age.
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Affiliation(s)
- Ching Wen Tseng
- Division of Pediatric Infectious Diseases, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- The Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- * E-mail: (CWT); (GYL)
| | - Pierre A. Kyme
- Division of Pediatric Infectious Diseases, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- The Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Andrea Arruda
- Division of Pediatric Infectious Diseases, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- The Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - V. Krishnan Ramanujan
- Department of Surgery & Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Wafa Tawackoli
- Department of Surgery & Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - George Y. Liu
- Division of Pediatric Infectious Diseases, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- The Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- * E-mail: (CWT); (GYL)
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Adhikari RP, Ajao AO, Aman MJ, Karauzum H, Sarwar J, Lydecker AD, Johnson JK, Nguyen C, Chen WH, Roghmann MC. Lower antibody levels to Staphylococcus aureus exotoxins are associated with sepsis in hospitalized adults with invasive S. aureus infections. J Infect Dis 2012; 206:915-23. [PMID: 22807524 DOI: 10.1093/infdis/jis462] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Staphylococcus aureus has numerous virulence factors, including exotoxins that may increase the severity of infection. This study was aimed at assessing whether preexisting antibodies to S. aureus toxins are associated with a lower risk of sepsis in adults with S. aureus infection complicated by bacteremia. METHODS We prospectively identified adults with S. aureus infection from 4 hospitals in Baltimore, MD, in 2009–2011. We obtained serum samples from prior to or at presentation of S. aureus bacteremia to measure total immunoglobulin G (IgG) and IgG antibody levels to 11 S. aureus exotoxins. Bacterial isolates were tested for the genes encoding S. aureus exotoxins using polymerase chain reaction (PCR). RESULTS One hundred eligible subjects were included and 27 of them developed sepsis. When adjusted for total IgG levels and stratified for the presence of toxin in the infecting isolate as appropriate, the risk of sepsis was significantly lower in those patients with higher levels of IgG against α-hemolysin (Hla), δ-hemolysin (Hld), Panton Valentine leukocidin (PVL), staphylococcal enterotoxin C-1 (SEC-1), and phenol-soluble modulin α3 (PSM-α3). CONCLUSIONS Our results suggest that higher antibody levels against Hla, Hld, PVL, SEC-1, and PSM-α3 may protect against sepsis in patients with invasive S. aureus infections.
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Watkins RR, David MZ, Salata RA. Current concepts on the virulence mechanisms of meticillin-resistant Staphylococcus aureus. J Med Microbiol 2012; 61:1179-1193. [PMID: 22745137 DOI: 10.1099/jmm.0.043513-0] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Meticillin-resistant Staphylococcus aureus (MRSA) strains are prevalent bacterial pathogens that cause both health care and community-associated infections. Increasing resistance to commonly prescribed antibiotics has made MRSA a serious threat to public health throughout the world. The USA300 strain of MRSA has been responsible for an epidemic of community-associated infections in the US, mostly involving skin and soft tissue but also more serious invasive syndromes such as pneumonia, severe sepsis and endocarditis. MRSA strains are particularly serious and potentially lethal pathogens that possess virulence mechanisms including toxins, adhesins, enzymes and immunomodulators. One of these is Panton-Valentine leukocidin (PVL), a toxin associated with abscess formation and severe necrotizing pneumonia. Earlier studies suggested that PVL was a major virulence factor in community-associated MRSA infections. However, some recent data have not supported this association while others have, leading to controversy. Therefore, investigators continue to search for additional mechanisms of pathogenesis. In this review, we summarize the current understanding of the biological basis of MRSA virulence and explore future directions for research, including potential vaccines and antivirulence therapies under development that might allow clinicians to more successfully treat and prevent MRSA infections.
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Affiliation(s)
- Richard R Watkins
- Division of Infectious Diseases, Akron General Medical Center, Akron, OH 44302, USA
| | - Michael Z David
- Departments of Medicine and Health Studies, The University of Chicago, Chicago, IL, USA
| | - Robert A Salata
- Division of Infectious Diseases and HIV Medicine, University Hospitals Case Medical Center, Cleveland, OH, USA
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Immune-activating properties of Panton-Valentine leukocidin improve the outcome in a model of methicillin-resistant Staphylococcus aureus pneumonia. Infect Immun 2012; 80:2894-904. [PMID: 22665379 DOI: 10.1128/iai.06360-11] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Panton-Valentine leukocidin (PVL) is a cytotoxin expressed by many methicillin-resistant Staphylococcus aureus (MRSA) strains that cause community-acquired infections (CA-MRSA). Its role in virulence however, is controversial, with clinical data suggesting that PVL-producing strains may cause less severe disease in humans. PVL is capable of lysing human white blood cells, but at sublytic amounts, PVL can activate protective host immunity in the absence of cell damage. The concentration-dependent reactions it elicits from host cells could be the reason for seemingly contradictory results about PVL's role in virulence. We hypothesized that a key to understanding PVL's action on host cells and, possibly, outcomes from infection is the amount of toxin present, a hypothesis previously supported in studies using a low-inoculum skin infection model, where low levels of PVL augmented innate immune resistance to infection. Here, we present additional data supporting this hypothesis using a mouse model of MRSA pneumonia, wherein we found increased virulence of isogenic Δpvl strains and further confirmed PVL's capacity to activate proinflammatory responses from mouse and human neutrophils and pulmonary cells. Activation was measured as the production of phosphorylated p38 mitogen-activated protein kinase (MAPK) and proinflammatory cytokines interleukin-8 (IL-8) and KC (from human and mouse cells, respectively), as well as the release of antibacterial factors. Conversely, PVL lowered the levels of tumor necrosis factor alpha (TNF-α) produced in active pulmonary infection, while low doses induced apoptosis, suggesting that PVL also has the capacity to regulate inflammation. Our data indicate that, independent of its cytotoxic effects, PVL also plays an important and positive immunomodulatory role during MRSA infections.
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Galy R, Bergeret F, Keller D, Mourey L, Prévost G, Maveyraud L. Crystallization and preliminary crystallographic studies of both components of the staphylococcal LukE-LukD leukotoxin. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:663-7. [PMID: 22684065 PMCID: PMC3370905 DOI: 10.1107/s1744309112014662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 04/04/2012] [Indexed: 06/01/2023]
Abstract
Soluble forms of recombinant LukE protein (expressed in Escherichia coli) and of wild-type LukD protein (expressed in Staphylococcus aureus), which together form the staphylococcal LukE-LukD leukotoxin, were purified to homogeneity and crystallized using the sitting-drop vapour-diffusion method. The crystals of LukE belonged to space group I4, with unit-cell parameters a = b = 134.50, c = 64.43 Å, and diffracted X-rays to 1.6 Å resolution. The crystals of LukD belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 48.04, b = 50.99, c = 137.40 Å, and diffracted to 1.9 Å resolution. Molecular replacement using the LukF-PV structure (PDB entry 1pvl) as a template model allowed the identification of an initial structure solution for the LukD data. In the case of LukE, a solution comprising only a single copy of the search model (LukS-PV; PDB entry 1t5r) was found, although the unit-cell parameters indicated that up to three molecules could be accommodated in the asymmetric unit.
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Affiliation(s)
- Romain Galy
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France
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High genetic diversity among community-associated Staphylococcus aureus in Europe: results from a multicenter study. PLoS One 2012; 7:e34768. [PMID: 22558099 PMCID: PMC3338755 DOI: 10.1371/journal.pone.0034768] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 03/05/2012] [Indexed: 01/22/2023] Open
Abstract
Background Several studies have addressed the epidemiology of community-associated
Staphylococcus aureus (CA-SA) in Europe; nonetheless, a
comprehensive perspective remains unclear. In this study, we aimed to
describe the population structure of CA-SA and to shed light on the origin
of methicillin-resistant S. aureus (MRSA) in this
continent. Methods and Findings A total of 568 colonization and infection isolates, comprising both MRSA and
methicillin-susceptible S. aureus (MSSA), were recovered in
16 European countries, from community and community-onset infections. The
genetic background of isolates was characterized by molecular typing
techniques (spa typing, pulsed-field gel electrophoresis
and multilocus sequence typing) and the presence of PVL and ACME was tested
by PCR. MRSA were further characterized by SCCmec typing.
We found that 59% of all isolates were associated with
community-associated clones. Most MRSA were related with USA300 (ST8-IVa and
variants) (40%), followed by the European clone (ST80-IVc and
derivatives) (28%) and the Taiwan clone (ST59-IVa and related clonal
types) (15%). A total of 83% of MRSA carried Panton-Valentine
leukocidin (PVL) and 14% carried the arginine catabolic mobile
element (ACME). Surprisingly, we found a high genetic diversity among MRSA
clonal types (ST-SCCmec), Simpson’s index of
diversity = 0.852 (0.788–0.916). Specifically,
about half of the isolates carried novel associations between genetic
background and SCCmec. Analysis by BURP showed that some
CA-MSSA and CA-MRSA isolates were highly related, suggesting a probable
local acquisition/loss of SCCmec. Conclusions Our results imply that CA-MRSA origin, epidemiology and population structure
in Europe is very dissimilar from that of USA.
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Cheung GYC, Otto M. The potential use of toxin antibodies as a strategy for controlling acute Staphylococcus aureus infections. Expert Opin Ther Targets 2012; 16:601-12. [PMID: 22530584 DOI: 10.1517/14728222.2012.682573] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION The pandemic human pathogen, Staphylococcus aureus, displays high levels of antibiotic resistance and is a major cause of hospital- and community-associated infections. S. aureus disease manifestation is to a great extent due to the production of a large arsenal of virulence factors, which include a series of secreted toxins. Antibodies to S. aureus toxins are found in people who are infected or asymptomatically colonized with S. aureus. Immunotherapies consisting of neutralizing anti-toxin antibodies could provide immediate aid to patients with impaired immune systems or in advanced stages of disease. AREAS COVERED Important S. aureus toxins, their roles in pathogenesis, rationales for selecting S. aureus toxins for immunization efforts, and caveats associated with monoclonal antibody-based passive immunization are discussed. This review will focus on hyper-virulent community-associated methicillin-resistant S. aureus because of their recent surge and clinical importance. EXPERT OPINION Antibodies against genome-encoded toxins may be more broadly applicable than those directed against toxins found only in a sub-population of S. aureus isolates. Furthermore, there is substantial functional redundancy among S. aureus toxins. Thus, an optimal anti-S. aureus formulation may consist of multiple antibodies directed against a series of key S. aureus genome-encoded toxins.
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Affiliation(s)
- Gordon Y C Cheung
- Laboratory of Human Bacterial Pathogenesis, NIAID, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA
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39
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CodY deletion enhances in vivo virulence of community-associated methicillin-resistant Staphylococcus aureus clone USA300. Infect Immun 2012; 80:2382-9. [PMID: 22526672 DOI: 10.1128/iai.06172-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The Staphylococcus aureus global regulator CodY responds to nutrient availability by controlling the expression of target genes. In vitro, CodY represses the transcription of virulence genes, but it is not known if CodY also represses virulence in vivo. The dominant community-associated methicillin-resistant S. aureus (CA-MRSA) clone, USA300, is hypervirulent and has increased transcription of global regulators and virulence genes; these features are reminiscent of a strain defective in CodY. Sequence analysis revealed, however, that the codY genes of USA300 and other sequenced S. aureus isolates are not significantly different from the codY genes in strains known to have active CodY. codY was expressed in USA300, as well as in other pulsotypes assessed. Deletion of codY from a USA300 clinical isolate resulted in modestly increased expression of the global regulators agr and saeRS, as well as the gene encoding the toxin alpha-hemolysin (hla). A substantial increase (>30-fold) in expression of the lukF-PV gene, encoding part of the Panton-Valentine leukocidin (PVL), was observed in the codY mutant. All of these expression differences were reversed by complementation with a functional codY gene. Moreover, purified CodY protein bound upstream of the lukSF-PV operon, indicating that CodY directly represses expression of lukSF-PV. Deletion of codY increased the virulence of USA300 in necrotizing pneumonia and skin infection. Interestingly, deletion of lukSF-PV from the codY mutant did not attenuate virulence, indicating that the hypervirulence of the codY mutant was not explained by overexpression of PVL. These results demonstrate that CodY is active in USA300 and that CodY-mediated repression restrains the virulence of USA300.
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40
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Ma X, Chang W, Zhang C, Zhou X, Yu F. Staphylococcal Panton-Valentine leukocidin induces pro-inflammatory cytokine production and nuclear factor-kappa B activation in neutrophils. PLoS One 2012; 7:e34970. [PMID: 22529963 PMCID: PMC3329533 DOI: 10.1371/journal.pone.0034970] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 03/08/2012] [Indexed: 12/21/2022] Open
Abstract
Panton-Valentine leukocidin (PVL) is a cytotoxin secreted by Staphylococcus aureus and associated with severe necrotizing infections. PVL targets polymorphonuclear leukocytes, especially neutrophils, which are the first line of defense against infections. Although PVL can induce neutrophil death by necrosis or apoptosis, the specific inflammatory responses of neutrophils to this toxin are unclear. In this study, both in vivo and in vitro studies demonstrated that recombinant PVL has an important cytotoxic role in human neutrophils, leading to apoptosis at low concentrations and necrosis at high concentrations. Recombinant PVL also increased the levels of pro-inflammatory cytokine secretion from neutrophils. The up-regulation of pro-inflammatory cytokines was due to nuclear factor-kappa B (NF-κB) activation induced by PVL. Moreover, blocking NF-κB inhibited the production of inflammatory cytokines. To test the role of neutrophil immune responses during the pathogenesis of PVL-induced acute lung injury, we used immunocompetent or neutropenic rabbits to develop a model of necrotizing pneumonia. Immunocompetent rabbits challenged with PVL demonstrated increased inflammation containing neutrophilic infiltrates. In addition, there were elevated levels of inflammatory cytokines (IL-6, IL-8, TNF-α and IL-10) and NF-κB in the lung homogenate. In contrast, the lung tissues from neutropenic rabbits contained mild or moderate inflammation, and the levels of inflammatory cytokines and NF-κB increased only slightly. Data from the current study support growing evidence that neutrophils play an important role in the pathogenesis of PVL-induced tissue injury and inflammation. PVL can stimulate neutrophils to release pro-inflammatory mediators, thereby causing an acute inflammatory response. The ability of PVL to induce inflammatory cytokine release may be associated with the activation of NF-κB or its pore-forming properties.
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Affiliation(s)
- Xiaoling Ma
- Department of Laboratory Medicine, Anhui Provincial Hospital, Anhui Medical University, Hefei, China.
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41
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Ning RD, Zhang XL, Li QT, Guo XK. The effect of Staphylococcus aureus on apoptosis of cultured human osteoblasts. Orthop Surg 2012; 3:199-204. [PMID: 22009652 DOI: 10.1111/j.1757-7861.2011.00146.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE To investigate the effect of Staphylococcus aureus (S. aureus) on cultured human osteoblast apoptosis and the corresponding mode of action. METHODS Transmission electron microscopy (TEM), assessment of DNA laddering, and flow cytometry assays were used to investigate human osteoblast apoptosis following infection with S. aureus. RESULTS TEM examination and DNA laddering assessment indicated that S. aureus can induce cultured human osteoblast apoptosis. Flow cytometry assays showed that human osteoblast apoptosis occurs in a dose-dependent manner following infection with S. aureus. In addition, compared with under co-culture conditions, inhibition of invasion by S. aureus resulted in a 64.62% reduction in the percentage of early apoptotic cells (P < 0.01); 7.09% ± 1.21% of human osteoblasts under indirect co-culture with S. aureus at a multiplicity of infection of 250 showed an early apoptotic profile compared with uninfected controls(P < 0.01). CONCLUSIONS S. aureus induces cultured human osteoblast apoptosis in a dose-dependent manner. Intracellular S. aureus is mainly responsible for cultured human osteoblast apoptosis following infection; secreted soluble factor(s) of S. aureus playing a minor role in this process.
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Affiliation(s)
- Ren-de Ning
- Department of Orthopaedics, the Third Affiliated Hospital of Anhui Medical University, Hefei, China
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42
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Vandenesch F, Lina G, Henry T. Staphylococcus aureus hemolysins, bi-component leukocidins, and cytolytic peptides: a redundant arsenal of membrane-damaging virulence factors? Front Cell Infect Microbiol 2012; 2:12. [PMID: 22919604 PMCID: PMC3417661 DOI: 10.3389/fcimb.2012.00012] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 01/31/2012] [Indexed: 12/17/2022] Open
Abstract
One key aspect of the virulence of Staphylococcus aureus lies in its ability to target the host cell membrane with a large number of membrane-damaging toxins and peptides. In this review, we describe the hemolysins, the bi-component leukocidins (which include the Panton Valentine leukocidin, LukAB/GH, and LukED), and the cytolytic peptides (phenol soluble modulins). While at first glance, all of these factors might appear redundant, it is now clear that some of these factors play specific roles in certain S. aureus life stages and diseases or target specific cell types or species. In this review, we present an update of the literature on toxin receptors and their cell type and species specificities. Furthermore, we review epidemiological studies and animal models illustrating the role of these membrane-damaging factors in various diseases. Finally, we emphasize the interplay of these factors with the host immune system and highlight all their non-lytic functions.
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Affiliation(s)
- François Vandenesch
- Bacterial Pathogenesis and Innate Immunity Laboratory, INSERM U851 "Immunity, Infection and Vaccination," Lyon, France
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43
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Comparative genomic analysis of the genus Staphylococcus including Staphylococcus aureus and its newly described sister species Staphylococcus simiae. BMC Genomics 2012; 13:38. [PMID: 22272658 PMCID: PMC3317825 DOI: 10.1186/1471-2164-13-38] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 01/24/2012] [Indexed: 01/28/2023] Open
Abstract
Background Staphylococcus belongs to the Gram-positive low G + C content group of the Firmicutes division of bacteria. Staphylococcus aureus is an important human and veterinary pathogen that causes a broad spectrum of diseases, and has developed important multidrug resistant forms such as methicillin-resistant S. aureus (MRSA). Staphylococcus simiae was isolated from South American squirrel monkeys in 2000, and is a coagulase-negative bacterium, closely related, and possibly the sister group, to S. aureus. Comparative genomic analyses of closely related bacteria with different phenotypes can provide information relevant to understanding adaptation to host environment and mechanisms of pathogenicity. Results We determined a Roche/454 draft genome sequence for S. simiae and included it in comparative genomic analyses with 11 other Staphylococcus species including S. aureus. A genome based phylogeny of the genus confirms that S. simiae is the sister group to S. aureus and indicates that the most basal Staphylococcus lineage is Staphylococcus pseudintermedius, followed by Staphylococcus carnosus. Given the primary niche of these two latter taxa, compared to the other species in the genus, this phylogeny suggests that human adaptation evolved after the split of S. carnosus. The two coagulase-positive species (S. aureus and S. pseudintermedius) are not phylogenetically closest but share many virulence factors exclusively, suggesting that these genes were acquired by horizontal transfer. Enrichment in genes related to mobile elements such as prophage in S. aureus relative to S. simiae suggests that pathogenesis in the S. aureus group has developed by gene gain through horizontal transfer, after the split of S. aureus and S. simiae from their common ancestor. Conclusions Comparative genomic analyses across 12 Staphylococcus species provide hypotheses about lineages in which human adaptation has taken place and contributions of horizontal transfer in pathogenesis.
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Do differences in Panton-Valentine leukocidin production among international methicillin-resistant Staphylococcus aureus clones affect disease presentation and severity? J Clin Microbiol 2012; 50:1773-6. [PMID: 22205815 DOI: 10.1128/jcm.06421-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Panton-Valentine leukocidin (PVL) production by methicillin-resistant Staphylococcus aureus (MRSA) was determined in vitro using the enzyme-linked immunosorbent assay (ELISA), and associations with clinical presentation and bacterial genetic characteristics were examined. PVL production ranged from 0.02 to 4.865 μg/ml and correlated with a multilocus sequence type (MLST) clonal complex associated with specific PVL phage types. A relationship between PVL production and clinical presentation or patient demographics could not be demonstrated.
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45
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Targeting the host–pathogen interface for treatment of Staphylococcus aureus infection. Semin Immunopathol 2011; 34:299-315. [DOI: 10.1007/s00281-011-0297-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 10/17/2011] [Indexed: 12/15/2022]
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Rigby KM, DeLeo FR. Neutrophils in innate host defense against Staphylococcus aureus infections. Semin Immunopathol 2011; 34:237-59. [PMID: 22080185 PMCID: PMC3271231 DOI: 10.1007/s00281-011-0295-3] [Citation(s) in RCA: 269] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 10/14/2011] [Indexed: 12/29/2022]
Abstract
Staphylococcus aureus has been an important human pathogen throughout history and is currently a leading cause of bacterial infections worldwide. S. aureus has the unique ability to cause a continuum of diseases, ranging from minor skin infections to fatal necrotizing pneumonia. Moreover, the emergence of highly virulent, drug-resistant strains such as methicillin-resistant S. aureus in both healthcare and community settings is a major therapeutic concern. Neutrophils are the most prominent cellular component of the innate immune system and provide an essential primary defense against bacterial pathogens such as S. aureus. Neutrophils are rapidly recruited to sites of infection where they bind and ingest invading S. aureus, and this process triggers potent oxidative and non-oxidative antimicrobial killing mechanisms that serve to limit pathogen survival and dissemination. S. aureus has evolved numerous mechanisms to evade host defense strategies employed by neutrophils, including the ability to modulate normal neutrophil turnover, a process critical to the resolution of acute inflammation. Here we provide an overview of the role of neutrophils in host defense against bacterial pathogens and discuss strategies employed by S. aureus to circumvent neutrophil function.
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Affiliation(s)
- Kevin M Rigby
- Laboratory of Human Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840, USA
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47
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Deville JG, Equils O, Huang DB, Ang JY. The impact of linezolid and vancomycin treatment on local signs and symptoms of inflammation among pediatric patients with complicated skin and skin structure infections. Clin Pediatr (Phila) 2011; 50:1064-7. [PMID: 21098522 DOI: 10.1177/0009922810385107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Jaime G Deville
- University of California at Los Angeles, Los Angeles, CA, USA
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48
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Changchien CH, Chen YY, Chen SW, Chen WL, Tsay JG, Chu C. Retrospective study of necrotizing fasciitis and characterization of its associated methicillin-resistant Staphylococcus aureus in Taiwan. BMC Infect Dis 2011; 11:297. [PMID: 22040231 PMCID: PMC3221646 DOI: 10.1186/1471-2334-11-297] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 10/31/2011] [Indexed: 12/23/2022] Open
Abstract
Background Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a prevalent pathogen of necrotizing fasciitis (NF) in Taiwan. A four-year NF cases and clinical and genetic differences between hospital acquired (HA)- and community-acquired (CA)-MRSA infection and isolates were investigated. Methods A retrospective study of 247 NF cases in 2004-2008 and antimicrobial susceptibilities, staphylococcal chromosomal cassette mec (SCCmec) types, pulsed field gel electrophoresis (PFGE) patterns, virulence factors, and multilocus sequence typing (MLST) of 16 NF-associated MRSA in 2008 were also evaluated. Results In 247 cases, 42 microbial species were identified. S. aureus was the major prevalent pathogen and MRSA accounted for 19.8% of NF cases. Most patients had many coexisting medical conditions, including diabetes mellitus, followed by hypertension, chronic azotemia and chronic hepatic disease in order of decreasing prevalence. Patients with MRSA infection tended to have more severe clinical outcomes in terms of amputation rate (p < 0.05) and reconstruction rate (p = 0.001) than those with methicillin-sensitive S. aureus or non-S. aureus infection. NF patients infected by HA-MRSA had a significantly higher amputation rate, comorbidity, C-reactive protein level, and involvement of lower extremity than those infected by CA-MRSA. In addition to over 90% of MRSA resistant to erythromycin and clindamycin, HA-MRSA was more resistant than CA-MRSA to trimethoprim-sulfamethoxazole (45.8% vs. 4%). ST59/pulsotype C/SCCmec IV and ST239/pulsotype A/SCCmec III isolates were the most prevalent CA- and HA-MRSA, respectively in 16 isolates obtained in 2008. In contrast to the gene for γ-hemolysin found in all MRSA, the gene for Panton-Valentine leukocidin was only identified in ST59 MRSA isolates. Other three virulence factors TSST-1, ETA, and ETB were occasionally identified in MRSA isolates tested. Conclusion NF patients with MRSA infection, especially HA-MRSA infection, had more severe clinical outcomes than those infected by other microbial. The prevalent NF-associated MRSA clones in Taiwan differed distinctly from the most predominant NF-associated USA300 CA-MRSA clone in the USA. Initial empiric antimicrobials with a broad coverage for MRSA should be considered in the treatment of NF patients in an endemic area.
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Affiliation(s)
- Chih-Hsuan Changchien
- Department of Microbiology, Immunology, and Biopharmaceuticals, National Chiayi University, No 300, University Road, Chiayi, 60004, Taiwan, ROC
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Park B, Iwase T, Liu GY. Intranasal application of S. epidermidis prevents colonization by methicillin-resistant Staphylococcus aureus in mice. PLoS One 2011; 6:e25880. [PMID: 21998712 PMCID: PMC3187813 DOI: 10.1371/journal.pone.0025880] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 09/12/2011] [Indexed: 01/31/2023] Open
Abstract
Methicillin-resistant S. aureus emerged in recent decades to become a leading cause of infection worldwide. Colonization with MRSA predisposes to infection and facilitates transmission of the pathogen; however, available regimens are ineffective at preventing MRSA colonization. Studies of human nasal flora suggest that resident bacteria play a critical role in limiting S. aureus growth, and prompted us to query whether application of commensal resident bacteria could prevent nasal colonization with MRSA. We established a murine model system to study this question, and showed that mice nasally pre-colonized with S. epidermidis became more resistant to colonization with MRSA. Our study suggests that application of commensal bacteria with antibiotics could represent a more effective strategy to prevent MRSA colonization.
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Affiliation(s)
- Bonggoo Park
- Division of Infectious Diseases, Department of Pediatrics, Research Division of Immunology, Department of Biomedical Sciences, and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Tadayuki Iwase
- Department of Bacteriology, The Jikei University School of Medicine, Tokyo, Japan
| | - George Y. Liu
- Division of Infectious Diseases, Department of Pediatrics, Research Division of Immunology, Department of Biomedical Sciences, and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- * E-mail:
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Fromageau A, Cunha P, Gilbert FB, Rainard P. Purified Staphylococcus aureus leukotoxin LukM/F' does not trigger inflammation in the bovine mammary gland. Microb Pathog 2011; 51:396-401. [PMID: 21951578 DOI: 10.1016/j.micpath.2011.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 09/12/2011] [Accepted: 09/15/2011] [Indexed: 12/01/2022]
Abstract
An early recruitment of neutrophils in mammary tissue and milk is considered an important component of the defense of the mammary gland against Staphylococcus aureus. We investigated whether the leukotoxin LukM/F', which is produced by a proportion of mastitis-causing strains of S. aureus, would be able to trigger inflammation in the udder. Infusion of purified LukM/F' toxin in lactating mammary glands did not cause neutrophil influx in milk, showing that the toxin was not able to cause mastitis on its own. Purified LukM/F' did not kill or stimulate mammary epithelial cells in culture. As expected, LukM bound to mammary macrophages and the complete LukM/F' toxin killed these cells, but subcytotoxic LukM/F' concentrations did not induce secretion of IL-8, TNF-α, IL-1β or IL-6 by macrophages. On the contrary, the production of these pro-inflammatory mediators by adhesion-stimulated macrophages was reduced. Overall, these results indicate that purified leukotoxin LukM/F' is not likely to contribute to the initiation of the inflammatory response and could even play an anti-inflammatory role in the mammary gland by inactivating macrophages.
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Affiliation(s)
- Angélina Fromageau
- INRA, UR 1282 Infectiologie Animale et Santé Publique, IASP Bat. 311, F-37380 Nouzilly, France
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