151
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Gong L, Devenish RJ, Prescott M. Autophagy as a macrophage response to bacterial infection. IUBMB Life 2012; 64:740-7. [PMID: 22815102 DOI: 10.1002/iub.1070] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 06/13/2012] [Indexed: 01/07/2023]
Abstract
The macrophage is a key component of host defense mechanisms against pathogens. In addition to the phagocytosis of bacteria and secretion of proinflammatory mediators by macrophages, autophagy, a process involved in turnover of cellular material, is a recently identified component of the immune response to bacterial infection. Despite the bactericidal effect of autophagy, some species of intracellular bacteria are able to survive by using one or more strategies to avoid host autophagic attack. Here, we review the latest findings on the interactions between bacteria and autophagy in macrophages.
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Affiliation(s)
- Lan Gong
- Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Vic., Australia
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152
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Rosales-Reyes R, Saldías MS, Aubert DF, El-Halfawy OM, Valvano MA. The suhB gene of Burkholderia cenocepacia is required for protein secretion, biofilm formation, motility and polymyxin B resistance. MICROBIOLOGY-SGM 2012; 158:2315-2324. [PMID: 22767545 DOI: 10.1099/mic.0.060988-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia cenocepacia is a member of the Burkholderia cepacia complex (Bcc), a group of Gram-negative opportunistic pathogens that cause severe lung infections in patients with cystic fibrosis and display extreme intrinsic resistance to antibiotics, including antimicrobial peptides. B. cenocepacia BCAL2157 encodes a protein homologous to SuhB, an inositol-1-monophosphatase from Escherichia coli, which was suggested to participate in post-transcriptional control of gene expression. In this work we show that a deletion of the suhB-like gene in B. cenocepacia (ΔsuhB(Bc)) was associated with pleiotropic phenotypes. The ΔsuhB(Bc) mutant had a growth defect manifested by an almost twofold increase in the generation time relative to the parental strain. The mutant also had a general defect in protein secretion, motility and biofilm formation. Further analysis of the type II and type VI secretion systems (T2SS and T6SS) activities revealed that these secretion systems were inactive in the ΔsuhB(Bc) mutant. In addition, the mutant exhibited increased susceptibility to polymyxin B but not to aminoglycosides such as gentamicin and kanamycin. Together, our results demonstrate that suhB(Bc) deletion compromises general protein secretion, including the activity of the T2SS and the T6SS, and affects polymyxin B resistance, motility and biofilm formation. The pleiotropic effects observed upon suhB(Bc) deletion demonstrate that suhB(Bc) plays a critical role in the physiology of B. cenocepacia.
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Affiliation(s)
- Roberto Rosales-Reyes
- Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, México D.F., C.P. 02200 México.,Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - María Soledad Saldías
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Daniel F Aubert
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Omar M El-Halfawy
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt.,Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Miguel A Valvano
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
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153
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Kopp BT, Abdulrahman BA, Khweek AA, Kumar SB, Akhter A, Montione R, Tazi MF, Caution K, McCoy K, Amer AO. Exaggerated inflammatory responses mediated by Burkholderia cenocepacia in human macrophages derived from Cystic fibrosis patients. Biochem Biophys Res Commun 2012; 424:221-7. [PMID: 22728038 DOI: 10.1016/j.bbrc.2012.06.066] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 06/15/2012] [Indexed: 10/28/2022]
Abstract
Cystic fibrosis (CF) is accompanied with heightened inflammation worsened by drug resistant Burkholderia cenocepacia. Human CF macrophage responses to B. cenocepacia are poorly characterized and variable in the literature. Therefore, we examined human macrophage responses to the epidemic B. cenocepacia J2315 strain in order to identify novel anti-inflammatory targets. Peripheral blood monocyte derived macrophages were obtained from 23 CF and 27 non-CF donors. Macrophages were infected with B. cenocepacia J2315 and analyzed for cytokines, cytotoxicity, and microscopy. CF macrophages demonstrated significant increases in IL-1β, IL-10, MCP-1, and IFN-γ production in comparison to non-CF controls. CF patients on prednisone exhibited globally diminished cytokines compared to controls and other CF patients. CF macrophages also displayed increased bacterial burden and cell death. In conclusion, CF macrophages demonstrate exaggerated IL-1β, IL-10, MCP-1, and IFN-γ production and cell death during B. cenocepacia infection. Treatment with corticosteroids acutely suppressed cytokine responses.
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Affiliation(s)
- Benjamin T Kopp
- Section of Pediatric Pulmonology, Nationwide Children's Hospital, Columbus, OH, United States.
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154
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Akhter A, Caution K, Abu Khweek A, Tazi M, Abdulrahman BA, Abdelaziz DHA, Voss OH, Doseff AI, Hassan H, Azad AK, Schlesinger LS, Wewers MD, Gavrilin MA, Amer AO. Caspase-11 promotes the fusion of phagosomes harboring pathogenic bacteria with lysosomes by modulating actin polymerization. Immunity 2012; 37:35-47. [PMID: 22658523 DOI: 10.1016/j.immuni.2012.05.001] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 03/14/2012] [Accepted: 05/02/2012] [Indexed: 01/24/2023]
Abstract
Inflammasomes are multiprotein complexes that include members of the NLR (nucleotide-binding domain leucine-rich repeat containing) family and caspase-1. Once bacterial molecules are sensed within the macrophage, the inflammasome is assembled, mediating the activation of caspase-1. Caspase-11 mediates caspase-1 activation in response to lipopolysaccharide and bacterial toxins, and yet its role during bacterial infection is unknown. Here, we demonstrated that caspase-11 was dispensable for caspase-1 activation in response to Legionella, Salmonella, Francisella, and Listeria. We also determined that active mouse caspase-11 was required for restriction of L. pneumophila infection. Similarly, human caspase-4 and caspase-5, homologs of mouse caspase-11, cooperated to restrict L. pneumophila infection in human macrophages. Caspase-11 promoted the fusion of the L. pneumophila vacuole with lysosomes by modulating actin polymerization through cofilin. However, caspase-11 was dispensable for the fusion of lysosomes with phagosomes containing nonpathogenic bacteria, uncovering a fundamental difference in the trafficking of phagosomes according to their cargo.
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Affiliation(s)
- Anwari Akhter
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210, USA
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