Utility of the Citrobacter rodentium infection model in laboratory mice.
ABSTRACT There have been considerable advances in our understanding of the molecular pathogenesis of enteropathogenic Escherichia coli and enterohemorrhagic E. coli infection. Given the difficulty of infecting laboratory mice with these diarrhea-causing pathogens, a growing number of studies have found the murine bacterial pathogen Citrobacter rodentium to provide a robust, relevant in-vivo model system.
All inbred strains and outbred stocks of laboratory mice studied to date have been found to be susceptible to C. rodentium infection. The natural course of disease ranges from subclinical epithelial hyperplasia in the colon, to clinical diarrhea and colitis, to fatal infection, depending on the age, genetic background, and health status of the host. Infection is self-limiting, leading to disease resolution and protective immunity. Here we review recent discoveries related to bacterial virulence determinants, epithelial hyperplasia, innate and adaptive immune responses, and mechanisms of diarrhea.
Infection of laboratory mice with C. rodentium provides a useful in-vivo model for studying the pathogenesis of infectious gastroenteritis and acute diarrheal illness, and for preclinical evaluation of candidate preventive and therapeutic agents.
Article: CX(3)CR1(+) macrophages support IL-22 production by innate lymphoid cells during infection with Citrobacter rodentium.[show abstract] [hide abstract]
ABSTRACT: Innate immune cells, such as intestinal epithelial cells, dendritic cells (DCs), macrophages, granulocytes, and innate lymphoid cells provide a first line of defence to enteric pathogens. To study the role of CX(3)CR1(+) DCs and macrophages in host defence, we infected CX(3)CR1-GFP animals with Citrobacter rodentium. When transgenic CX(3)CR1-GFP animals are infected with the natural mouse pathogen C. rodentium, CX(3)CR1(-/-) animals showed a delayed clearance of C. rodentium as compared with (age- and sex-matched) wild-type B6 animals. The delayed clearance of C. rodentium is associated with reduced interleukin (IL)-22 expression. In C. rodentium-infected CX(3)CR1-GFP animals, IL-22 producing lymphoid-tissue inducer cells (LTi cells) were selectively reduced in the absence of CX(3)CR1. The reduced IL-22 expression correlates with decreased expression of the antimicrobial peptides RegIIIβ and RegIIIγ. The depletion of CX(3)CR1(+) cells by diphtheria toxin injection in CX(3)CR1-GFP × CD11c.DOG animals confirmed the role of CX(3)CR1(+) phagocytes in establishing IL-22 production, supporting the clearance of a C. rodentium infection.Mucosal Immunology advance online publication 1 August 2012. doi:10.1038/mi.2012.61.Mucosal Immunology 08/2012; · 6.96 Impact Factor
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ABSTRACT: Genetic complementation in many bacteria is commonly achieved by reintroducing functional copies of the mutated or deleted genes on a recombinant plasmid. Chromosomal integration systems using the Tn7 transposon have the advantage of providing a stable single-copy integration that does not require selective pressure. Previous Tn7 systems have been developed, although none have been shown to work effectively in a variety of enterobacteria. We have developed several mini-Tn7 and transposase vectors to provide a more versatile system. Transposition of Tn7 at the chromosomal attTn7 site was achieved by a classical conjugation approach, wherein the donor strain harbored the mini-Tn7 vector and the recipient strain possessed the transposase vector. This approach was efficient for five different pathogenic enterobacterial species. Thus, this system provides a useful tool for single-copy complementation at an episomal site for research in bacterial genetics and microbial pathogenesis. Furthermore, these vectors could also be used for the introduction of foreign genes for use in biotechnology applications, vaccine development, or gene expression and gene fusion constructs.Applied and environmental microbiology 06/2012; 78(17):6001-8. · 3.69 Impact Factor
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ABSTRACT: Enterohemorrhagic E. coli (EHEC) is an important subset of Shiga toxin-producing (Stx-producing) E. coli (STEC), pathogens that have been implicated in outbreaks of food-borne illness and can cause intestinal and systemic disease, including severe renal damage. Upon attachment to intestinal epithelium, EHEC generates "attaching and effacing" (AE) lesions characterized by intimate attachment and actin rearrangement upon host cell binding. Stx produced in the gut transverses the intestinal epithelium, causing vascular damage that leads to systemic disease. Models of EHEC infection in conventional mice do not manifest key features of disease, such as AE lesions, intestinal damage, and systemic illness. In order to develop an infection model that better reflects the pathogenesis of this subset of STEC, we constructed an Stx-producing strain of Citrobacter rodentium, a murine AE pathogen that otherwise lacks Stx. Mice infected with Stx-producing C. rodentium developed AE lesions on the intestinal epithelium and Stx-dependent intestinal inflammatory damage. Further, the mice experienced lethal infection characterized by histopathological and functional kidney damage. The development of a murine model that encompasses AE lesion formation and Stx-mediated tissue damage will provide a new platform upon which to identify EHEC alterations of host epithelium that contribute to systemic disease.The Journal of clinical investigation 10/2012; · 15.39 Impact Factor