151. Role of class 1 serine protease autotransporter in the pathogenesis of Citrobacter rodentium colitis
- Author
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Roy M. Robins-Browne, Rachel S. Smith, Mark A. Smith, James P. Nataro, Vidhya Vijayakumar, Araceli E. Santiago, and Fernando Ruiz-Perez
- Subjects
Colon ,Neutrophils ,T-Lymphocytes ,Immunology ,Mutant ,Bacterial Toxins ,Biology ,Microbiology ,Virulence factor ,Pathogenesis ,Mice ,Bacterial Proteins ,Citrobacter rodentium ,Animals ,RNA, Messenger ,Pathogen ,Serine protease ,Analysis of Variance ,B-Lymphocytes ,Gene Expression Regulation, Bacterial ,Bacterial Infections ,biology.organism_classification ,Colitis ,Enterobacteriaceae ,humanities ,Mice, Mutant Strains ,Mice, Inbred C57BL ,Disease Models, Animal ,Protein Transport ,Infectious Diseases ,biology.protein ,Cytokines ,Parasitology ,Tumor necrosis factor alpha ,Serine Proteases ,Gene Deletion - Abstract
A growing family of virulence factors called serine protease autotransporters of Enterobacteriaceae (SPATEs) are secreted by Shigella , Salmonella , and Escherichia coli pathotypes. SPATEs are subdivided into class 1 and class 2 based on structural features and phylogenetics. Class 1 SPATEs induce cytopathic effects in numerous epithelial cell lines, and several have been shown to cleave the cytoskeletal protein spectrin in vitro . However, to date the in vivo role of class 1 SPATEs in enteric pathogenesis is unknown. Citrobacter rodentium , a natural mouse pathogen, has recently been shown to harbor class 1 and class 2 SPATEs. To better understand the contribution of class 1 SPATEs in enteric infection, we constructed a class 1 SPATE null mutant (Δ crc1 ) in C. rodentium . Upon infection of C57BL/6 mice, the Δ crc1 mutant exhibited a hypervirulent, hyperinflammatory phenotype compared with its parent, accompanied by greater weight loss and a trend toward increased mortality in young mice; the effect was reversed when the crc1 gene was restored. Using flow cytometry, we observed increased infiltration of T cells, B cells, and neutrophils into the lamina propria of the distal colon in mice fed the Δ crc1 mutant, starting as early as 5 days after infection. No significant difference in epithelial cytotoxicity was observed. Reverse transcription-PCR (RT-PCR) analysis of distal colonic tissue on day 10 postinfection showed significant increases in mRNA encoding cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), IL-1β, and inducible nitric oxide synthase (iNOS) but not in mRNA encoding IL-17, IL-4, or IL-10 in the Δ crc1 mutant-infected mice. Our data suggest a previously unsuspected role for class 1 SPATEs in enteric infection.
- Published
- 2014