Effect of Water-Soluble Fraction from Lysozyme-Treated Enterococcus faecalis FK-23 on Mortality Caused by Influenza A Virus in Mice
Central Research Laboratories, Nichinichi Pharmaceutical Corporation Ltd., Mie, Japan. Viral immunology
(Impact Factor: 1.45).
02/2012; 25(1):86-90. DOI: 10.1089/vim.2011.0056
To maintain homeostasis of the immune system is considered important for the prevention of influenza A virus infection. Aberrant systemic inflammation is frequently induced by influenza A virus infection, and the severity of the symptoms is associated with pathogenicity of the virus. Lactic acid bacteria are known to have a positive effect in maintaining the immune system. Furthermore, preparations of a lactic acid bacteria strain, Enterococcus faecalis FK-23 (FK-23), have been reported to exert preferable homeostatic effects on immune diseases such as allergic rhinitis and early asthmatic responses. In this study, we examined the efficacy of the water-soluble fraction of lysed and heat-treated FK-23 (SLFK) against a lethal influenza A virus challenge. Mice were orally administered SLFK from day -7 to day 20, and intranasally infected with influenza virus A/Puerto Rico/8/34 (H1N1) at 10(3) PFU on day 0. The survival rate of SLFK-administered mice after influenza A virus infection was significantly improved compared with that of control mice. In addition, the mRNA expression level of the anti-inflammatory cytokine interleukin-10 (IL-10) in lung tissues was enhanced by the oral administration of SLFK after influenza A virus infection. These observations suggest that the oral administration of SLFK exerts a protective effect against influenza virus infection through the activation of the anti-inflammatory response.
Available from: Yosuke Nakayama
- "An influenza virus strain , A / Puerto Rico / 8 / 34 ( H1N1 ; PR8 ) was used in this study . The infectious materials were handled in a biosafety level 2 facility under approved proto - cols in accordance with guidelines of Hokkaido University . The virus was prepared as described previously ( Kondoh et al . 2012 ) . In brief , the virus was propagated in the al - lantoic cavities of 10 - day - old embryonated chicken eggs at 35°C for 48 h , and then was concentrated and purified by density gradient centrifugation . The purified virus was suspended in phosphate - buffered saline ( PBS ) and stored at −80°C until use ."
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ABSTRACT: Infection with influenza A virus, one of the most common life-threatening viruses, causes the accumulation of inflammatory cells in the lung, which is directly correlated with influenza-associated morbidity and mortality. In this study, we investigated the potential of lysozyme-treated Enterococcus faecalis FK-23 (LFK) to prevent influenza in influenza virus-infected mice. C57BL/6N mice were orally administered LFK and intranasally infected with influenza virus A/Puerto Rico/8/34 (H1N1) at lethal doses. After infection with influenza A virus, the survival rate of the LFK-administered mice was significantly higher than that of saline-administered mice. Staining of lung sections with hematoxylin-eosin, and cell counts of lung and bronchoalveolar lavage fluid showed that oral administration of LFK suppressed the excessive infiltration of leukocytes into the lung after viral infection. Extravasation assay revealed that the arrest was mediated by modulation of pulmonary alveolar-capillary permeability. Expression levels of genes involved in matrix degradation, which are correlated with vascular permeability, were downregulated in LFK-administered mice. These findings suggest that stabilizing the integrity of the alveolar-capillary barrier by the administration of LFK improves survival rate.
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Available from: PubMed Central
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ABSTRACT: When activated by viral infection, plasmacytoid dendritic cells (pDCs) play a primary role in the immune response through secretion of IFN-α. Lactococcus lactis subsp. lactis JCM5805 (JCM5805) is a strain of lactic acid bacteria (LAB) that activates murine and human pDCs to express type I and type III interferons (IFNs). JCM5805 has also been shown to activate pDCs via a Toll-like receptor 9 (TLR9) dependent pathway. In this study, we investigated the anti-viral effects of oral administration of JCM5805 using a mouse model of murine parainfluenza virus (mPIV1) infection. JCM5805-fed mice showed a drastic improvement in survival rate, prevention of weight loss, and reduction in lung histopathology scores compared to control mice. We further examined the mechanism of anti-viral effects elicited by JCM5805 administration using naive mice. Microscopic observations showed that JCM5805 was incorporated into CD11c+ immune cells in Peyer's patches (PP) and PP pDCs were significantly activated and the expression levels of IFNs were significantly increased. Interestingly, nevertheless resident pDCs at lung were not activated and expressions levels of IFNs at whole lung tissue were not influenced, the expressions of anti-viral factors induced by IFNs, such as Isg15, Oasl2, and Viperin, at lung were up-regulated in JCM5805-fed mice compared to control mice. Therefore expressed IFNs from intestine might be delivered to lung and IFN stimulated genes might be induced. Furthermore, elevated expressions of type I IFNs from lung lymphocytes were observed in response to mPIV1 ex vivo stimulation in JCM5805-fed mice compared to control. This might be due to increased ratio of pDCs located in lung were significantly increased in JCM5805 group. Taken together, a specific LAB strain might be able to affect anti-viral immunological profile in lung via activation of intestinal pDC leading to enhanced anti-viral phenotype in vivo.
Available from: Guido Werner
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ABSTRACT: Enterococcus faecalis is a multifaceted microorganism known to act as a beneficial intestinal commensal bacterium. It is also a dreaded nosocomial pathogen causing life-threatening infections in hospitalised patients. Isolates of a distinct MLST type ST40 represent the most frequent strain type of this species, distributed worldwide and originating from various sources (animal, human, environmental) and different conditions (colonisation/infection). Since enterococci are known to be highly recombinogenic we determined to analyse the microevolution and niche adaptation of this highly distributed clonal type.
We compared a set of 42 ST40 isolates by assessing key molecular determinants, performing whole genome sequencing (WGS) and a number of phenotypic assays including resistance profiling, formation of biofilm and utilisation of carbon sources. We generated the first circular closed reference genome of an E. faecalis isolate D32 of animal origin and compared it with the genomes of other reference strains. D32 was used as a template for detailed WGS comparisons of high-quality draft genomes of 14 ST40 isolates. Genomic and phylogenetic analyses suggest a high level of similarity regarding the core genome, also demonstrated by similar carbon utilisation patterns. Distribution of known and putative virulence-associated genes did not differentiate between ST40 strains from a commensal and clinical background or an animal or human source. Further analyses of mobile genetic elements (MGE) revealed genomic diversity owed to: (1) a modularly structured pathogenicity island; (2) a site-specifically integrated and previously unknown genomic island of 138 kb in two strains putatively involved in exopolysaccharide synthesis; and (3) isolate-specific plasmid and phage patterns. Moreover, we used different cell-biological and animal experiments to compare the isolate D32 with a closely related ST40 endocarditis isolate whose draft genome sequence was also generated. D32 generally showed a greater capacity of adherence to human cell lines and an increased pathogenic potential in various animal models in combination with an even faster growth in vivo (not in vitro).
Molecular, genomic and phenotypic analysis of representative isolates of a major clone of E. faecalis MLST ST40 revealed new insights into the microbiology of a commensal bacterium which can turn into a conditional pathogen.
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