Influenza A virus elevates active cathepsin B in primary murine DC

Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA.
International Immunology (Impact Factor: 2.54). 06/2007; 19(5):645-55. DOI: 10.1093/intimm/dxm030
Source: PubMed


Dendritic cells (DCs) act as a first-line recognition system for invading pathogens, such as influenza A. The interaction of DC with influenza A virus results in DC activation via endosomal Toll-like receptors and also leads to presentation of viral peptides on MHC class II molecules. Prior work demonstrated that influenza A virus (A/HKx31; H3N2) infection of BALB/c mice activates lung DCs for antigen presentation, and that the enhanced function of these cells persists long after viral clearance and resolution of the virus-induced inflammatory response. Whether influenza A virus has acute or longer-lasting effects on the endo/lysosomal antigen-processing machinery of DCs has not been studied. Here, we show that antigen presentation from intact protein antigen, but not peptide presentation, results in increased T cell stimulation by influenza-exposed lung DCs, suggesting increased antigen processing/loading in these DCs. We find that cathepsin (Cat) B levels and activity are substantially up-regulated in murine lung DCs, harvested 30 days after A/HKx31 infection. CatB levels and activity are also increased in murine splenic and bone marrow-derived DCs, following short-term in vitro exposure to UV-inactivated influenza A virus. Modest effects on CatX are also seen during in vivo and in vitro exposure to influenza A virus. Using a cell permeable Cat inhibitor, we show Cats in influenza-exposed DCs to be functional and required for generation of a T cell epitope from intact ovalbumin. Our findings indicate that influenza A virus affects the MHC class II antigen-processing pathway, an essential pathway for CD4(+) T cell activation.

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Available from: Matthew Bogyo, Oct 09, 2015
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    • "Due to the developed lysosomal apparatus, macrophages are showing microbicidal activity by the secretion of lysosomal proteases. In the conditions of viral infections the most important are proteolytic enzymes from the group of endopeptidase (lysozyme, cathepsin D, and myeloperoxidase ), asking for intracellular disintegration of the protein structures of viruses [18] [19]. Thus, the high pathogenicity of HPAI H5N1 in mammals is associated with the features of immune response. "
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    ABSTRACT: Highly pathogenic avian influenza H5N1 (HPAI H5N1) viruses can infect mammals, including humans, causing severe systemic disease with the inhibition of the immune system and a high mortality rate. In conditions of lymphoid tissue depletion, the liver plays an important role in host defence against viruses. The changes in mice liver infected with HPAI H5N1 virus A/goose/Krasnoozerskoye/627/05 have been studied. It has been shown that the virus persistence in the liver leads to the expression of proinflammatory cytokines (TNF- α , IL-6) and intracellular proteases (lysozyme, cathepsin D, and myeloperoxidase) by Kupffer cells. Defective antiviral response exacerbates destructive processes in the liver accelerating the development of liver failure.
    Clinical and Developmental Immunology 12/2013; 2013:342686. DOI:10.1155/2013/342686 · 2.93 Impact Factor
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    • "In this study, we showed that MDM released active cathepsin B and that HIV-1 infection increased levels of active cathepsin B over time of infection. Other groups have associated increased cathepsin B activity with infections by several other viruses, such as human Papilloma virus [68], Influenza A virus [69], Adeno-associated virus [70], and Norovirus [71]. In terms of cathepsin B’s mechanism of action after viral infection, our observations confirm the results of Furman’s group, and extend them by showing that not only does cathepsin B increase after viral infection, but the activity of secreted cathepsin B is also modulated. "
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    ABSTRACT: Chronic HIV infection leads to the development of cognitive impairments, designated as HIV-associated neurocognitive disorders (HAND). The secretion of soluble neurotoxic factors by HIV-infected macrophages plays a central role in the neuronal dysfunction and cell death associated with HAND. One potentially neurotoxic protein secreted by HIV-1 infected macrophages is cathepsin B. To explore the potential role of cathepsin B in neuronal cell death after HIV infection, we cultured HIV-1(ADA) infected human monocyte-derived macrophages (MDM) and assayed them for expression and activity of cathepsin B and its inhibitors, cystatins B and C. The neurotoxic activity of the secreted cathepsin B was determined by incubating cells from the neuronal cell line SK-N-SH with MDM conditioned media (MCM) from HIV-1 infected cultures. We found that HIV-1 infected MDM secreted significantly higher levels of cathepsin B than did uninfected cells. Moreover, the activity of secreted cathepsin B was significantly increased in HIV-infected MDM at the peak of viral production. Incubation of neuronal cells with supernatants from HIV-infected MDM resulted in a significant increase in the numbers of apoptotic neurons, and this increase was reversed by the addition of either the cathepsin B inhibitor CA-074 or a monoclonal antibody to cathepsin B. In situ proximity ligation assays indicated that the increased neurotoxic activity of the cathepsin B secreted by HIV-infected MDM resulted from decreased interactions between the enzyme and its inhibitors, cystatins B and C. Furthermore, preliminary in vivo studies of human post-mortem brain tissue suggested an upregulation of cathepsin B immunoreactivity in the hippocampus and basal ganglia in individuals with HAND. Our results demonstrate that HIV-1 infection upregulates cathepsin B in macrophages, increases cathepsin B activity, and reduces cystatin-cathepsin interactions, contributing to neuronal apoptosis. These findings provide new evidence for the role of cathepsin B in neuronal cell death induced by HIV-infected macrophages.
    PLoS ONE 05/2012; 7(5):e36571. DOI:10.1371/journal.pone.0036571 · 3.23 Impact Factor
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    • "It can thus function as both an initiator and executioner protease that acts upstream of cytochrome C release from mitochondria. Lastly, this protein has been shown to play multiple roles during viral infection such as PCD signaling with human papilloma virus [37] and uncoating of adeno-associated viruses 2 and 8 [38] and is induced by grass carp hemorrhage [39], and influenza A viruses [20,24,40]. "
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    ABSTRACT: Noroviruses are the leading cause of viral gastroenteritis. Because a suitable in vitro culture system for the human virus has yet to be developed, many basic details of the infection process are unknown. Murine norovirus (MNV) serves as a model system for the study of norovirus infection. Recently it was shown that infection of RAW 264.7 cells involved a novel apoptotic pathway involving survivin. Using a different set of approaches, the up-regulation of caspases, DNA condensation/fragmentation, and membrane blebbing, all of which are markers of apoptosis, were confirmed. Live cell imaging and activity-based protein profiling showed that activation of caspase-like proteases occurred within two hours of infection, followed by morphological changes to the cells. MNV infection in the presence of caspase inhibitors proceeded via a distinct pathway of rapid cellular necrosis and reduced viral production. Affinity purification of activity-based protein profiling targets and identification by peptide mass fingerprinting showed that the cysteine protease cathepsin B was activated early in infection, establishing this protein as an upstream activator of the intrinsic apoptotic pathway. This work adds cathepsin B to the noncanonical programmed cell death induced by MNV, and provides data suggesting that the virus may induce apoptosis to expand the window of time for viral replication. This work also highlights the significant power of activity-based protein profiling in the study of viral pathogenesis.
    Virology Journal 10/2009; 6(1):139. DOI:10.1186/1743-422X-6-139 · 2.18 Impact Factor
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