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Uropathogenic Escherichia coli P and Type 1 fimbriae act in synergy in a living host to facilitate renal colonization leading to nephron obstruction.

Melican K, Sandoval RM, Kader A, Josefsson L, Tanner GA, Molitoris BA, Richter-Dahlfors A - PLoS Pathog. (2011)

Bottom Line: The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h.Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen.Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden.

ABSTRACT
The progression of a natural bacterial infection is a dynamic process influenced by the physiological characteristics of the target organ. Recent developments in live animal imaging allow for the study of the dynamic microbe-host interplay in real-time as the infection progresses within an organ of a live host. Here we used multiphoton microscopy-based live animal imaging, combined with advanced surgical procedures, to investigate the role of uropathogenic Escherichia coli (UPEC) attachment organelles P and Type 1 fimbriae in renal bacterial infection. A GFP+ expressing variant of UPEC strain CFT073 and genetically well-defined isogenic mutants were microinfused into rat glomerulus or proximal tubules. Within 2 h bacteria colonized along the flat squamous epithelium of the Bowman's capsule despite being exposed to the primary filtrate. When facing the challenge of the filtrate flow in the proximal tubule, the P and Type 1 fimbriae appeared to act in synergy to promote colonization. P fimbriae enhanced early colonization of the tubular epithelium, while Type 1 fimbriae mediated colonization of the center of the tubule via a mechanism believed to involve inter-bacterial binding and biofilm formation. The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h. Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen. Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis.

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Expression, binding and infection characteristics of P and Type 1 isogenic strains.(A) qRT-PCR analysis of micro-dissected tissues 8 h after infusion with LT004 or PBS. Bars show cycle of threshold for detection of gfp+ (white), papA_2 (black) and fimA (grey) transcript. n/d  =  not detectable. Each group is from an individual animal (B) Relative agglutination of human O type red blood cells, indicating PapG mediated agglutination (black) and yeast cell agglutination in the absence of mannose, indicating FimH mediated agglutination (white) for indicated strains using LB medium as control. (C) Bacterial adhesion (counted per 40 cells) to A498 human renal epithelial cells. * P = 0.001, ** P = 0.045 Error bars in (a, c)  =  standard deviation. (D) Number of bacteria in the kidney, shown by CFU/g tissue, following a 4-day ascending infection.
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ppat-1001298-g002: Expression, binding and infection characteristics of P and Type 1 isogenic strains.(A) qRT-PCR analysis of micro-dissected tissues 8 h after infusion with LT004 or PBS. Bars show cycle of threshold for detection of gfp+ (white), papA_2 (black) and fimA (grey) transcript. n/d  =  not detectable. Each group is from an individual animal (B) Relative agglutination of human O type red blood cells, indicating PapG mediated agglutination (black) and yeast cell agglutination in the absence of mannose, indicating FimH mediated agglutination (white) for indicated strains using LB medium as control. (C) Bacterial adhesion (counted per 40 cells) to A498 human renal epithelial cells. * P = 0.001, ** P = 0.045 Error bars in (a, c)  =  standard deviation. (D) Number of bacteria in the kidney, shown by CFU/g tissue, following a 4-day ascending infection.

Mentions: Genetic analysis of the expression pattern of Type 1 and P fimbriae in carefully controlled in vitro experiments has shown that an individual E. coli bacterium express only one fimbriae type at a time due to co-regulation of the fimbriae operons [28], [29], [30]. To analyze the gene expression patterns of Type 1 and/or P fimbriae by UPEC colonizing the renal tubule, the spatial-temporally controlled micro-infusion model was used. Tissue infused with LT004 8 h previously was carefully excised and bacterial mRNA was isolated. qRT-PCR analysis revealed substantial expression of both major fimbriae structural proteins PapA_2 and FimA (Figure 2A). This suggested a bacterial population with heterogeneous expression of adhesion organelles at this early stage of infection.


Uropathogenic Escherichia coli P and Type 1 fimbriae act in synergy in a living host to facilitate renal colonization leading to nephron obstruction.

Melican K, Sandoval RM, Kader A, Josefsson L, Tanner GA, Molitoris BA, Richter-Dahlfors A - PLoS Pathog. (2011)

Expression, binding and infection characteristics of P and Type 1 isogenic strains.(A) qRT-PCR analysis of micro-dissected tissues 8 h after infusion with LT004 or PBS. Bars show cycle of threshold for detection of gfp+ (white), papA_2 (black) and fimA (grey) transcript. n/d  =  not detectable. Each group is from an individual animal (B) Relative agglutination of human O type red blood cells, indicating PapG mediated agglutination (black) and yeast cell agglutination in the absence of mannose, indicating FimH mediated agglutination (white) for indicated strains using LB medium as control. (C) Bacterial adhesion (counted per 40 cells) to A498 human renal epithelial cells. * P = 0.001, ** P = 0.045 Error bars in (a, c)  =  standard deviation. (D) Number of bacteria in the kidney, shown by CFU/g tissue, following a 4-day ascending infection.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3044688&req=5

ppat-1001298-g002: Expression, binding and infection characteristics of P and Type 1 isogenic strains.(A) qRT-PCR analysis of micro-dissected tissues 8 h after infusion with LT004 or PBS. Bars show cycle of threshold for detection of gfp+ (white), papA_2 (black) and fimA (grey) transcript. n/d  =  not detectable. Each group is from an individual animal (B) Relative agglutination of human O type red blood cells, indicating PapG mediated agglutination (black) and yeast cell agglutination in the absence of mannose, indicating FimH mediated agglutination (white) for indicated strains using LB medium as control. (C) Bacterial adhesion (counted per 40 cells) to A498 human renal epithelial cells. * P = 0.001, ** P = 0.045 Error bars in (a, c)  =  standard deviation. (D) Number of bacteria in the kidney, shown by CFU/g tissue, following a 4-day ascending infection.
Mentions: Genetic analysis of the expression pattern of Type 1 and P fimbriae in carefully controlled in vitro experiments has shown that an individual E. coli bacterium express only one fimbriae type at a time due to co-regulation of the fimbriae operons [28], [29], [30]. To analyze the gene expression patterns of Type 1 and/or P fimbriae by UPEC colonizing the renal tubule, the spatial-temporally controlled micro-infusion model was used. Tissue infused with LT004 8 h previously was carefully excised and bacterial mRNA was isolated. qRT-PCR analysis revealed substantial expression of both major fimbriae structural proteins PapA_2 and FimA (Figure 2A). This suggested a bacterial population with heterogeneous expression of adhesion organelles at this early stage of infection.

Bottom Line: The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h.Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen.Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden.

ABSTRACT
The progression of a natural bacterial infection is a dynamic process influenced by the physiological characteristics of the target organ. Recent developments in live animal imaging allow for the study of the dynamic microbe-host interplay in real-time as the infection progresses within an organ of a live host. Here we used multiphoton microscopy-based live animal imaging, combined with advanced surgical procedures, to investigate the role of uropathogenic Escherichia coli (UPEC) attachment organelles P and Type 1 fimbriae in renal bacterial infection. A GFP+ expressing variant of UPEC strain CFT073 and genetically well-defined isogenic mutants were microinfused into rat glomerulus or proximal tubules. Within 2 h bacteria colonized along the flat squamous epithelium of the Bowman's capsule despite being exposed to the primary filtrate. When facing the challenge of the filtrate flow in the proximal tubule, the P and Type 1 fimbriae appeared to act in synergy to promote colonization. P fimbriae enhanced early colonization of the tubular epithelium, while Type 1 fimbriae mediated colonization of the center of the tubule via a mechanism believed to involve inter-bacterial binding and biofilm formation. The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h. Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen. Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis.

Show MeSH
Related in: MedlinePlus