The aim of this study was to investigate the role of TLR2, TLR4 and MyD88 in sepsis-induced AKI. C57BL/6 TLR2−/−, TLR4−/− and MyD88−/− male mice were subjected to sepsis by cecal ligation and puncture (CLP). Twenty four hours later, kidney tissue and blood samples were collected for analysis. The TLR2−/−, TLR4−/− and MyD88−/− mice that were subjected to CLP had preserved renal morphology, and fewer areas of hypoxia and apoptosis compared with the wild-type C57BL/6 mice (WT). MyD88−/− mice were completely protected compared with the WT mice. We also observed reduced expression of proinflammatory cytokines in the kidneys of the knockout mice compared with those of the WT mice and subsequent inhibition of increased vascular permeability in the kidneys of the knockout mice. The WT mice had increased GR1+low cells migration compared with the knockout mice and decreased in GR1+high cells migration into the peritoneal cavity. The TLR2−/−, TLR4−/−, and MyD88−/− mice had lower neutrophil infiltration in the kidneys. Depletion of neutrophils in the WT mice led to protection of renal function and less inflammation in the kidneys of these mice. Innate immunity participates in polymicrobial sepsis-induced AKI, mainly through the MyD88 pathway, by leading to an increased migration of neutrophils to the kidney, increased production of proinflammatory cytokines, vascular permeability, hypoxia and apoptosis of tubular cells.

SummaryEnteropathogenic Escherichia coli (EPEC) forms attaching and effacing lesions in the intestinal mucosa characterized by intimate attachment to the epithelium by means of intimin (an outer membrane adhesin encoded by eae). EPEC is subgrouped into typical (tEPEC) and atypical (aEPEC); only tEPEC carries the EAF (EPEC adherence factor) plasmid that encodes the bundle-forming pilus (BFP). Characteristically, after 3 h of incubation, tEPEC produces localized adherence (LA) (with compact microcolonies) in HeLa/HEp-2 cells by means of BFP, whereas most aEPEC form looser microcolonies. We have previously identified nine aEPEC strains displaying LA in extended (6 h) assays (LA6). In this study, we analysed the kinetics of LA6 pattern development and the role of intimin in the process. Transmission electron microscopy and confocal laser microscopy showed that the invasive process of strain 1551-2 displays a LA phenotype. An eae-defective mutant of strain 1551-2 prevented the invasion although preserving intense diffused adherence. Sequencing of eae revealed that strain 1551-2 expresses the omicron subtype of intimin. We propose that the LA phenotype of aEPEC strain 1551-2 is mediated by intimin omicron and hypothesize that this strain expresses an additional novel adhesive structure. The present study is the first to report the association of compact microcolony formation and an intense invasive ability in aEPEC.

The presence of the pathogenicity island (PAI) O122 genes, efa1 (lifA), sen, pagC, nleB, and nleE, in typical and atypical enteropathogenic Escherichia coli (EPEC) strains was investigated. The simultaneous occurrence of all genes was statistically associated with diarrhea due to atypical EPEC. Detection of the complete PAI O122 could aid in the identification of potential pathogenic strains of atypical EPEC.Enteropathogenic Escherichia coli (EPEC) and Shiga toxin (Stx)-producing E. coli (STEC) are important human enteropathogens (9). EPEC is further subgrouped into typical (tEPEC) and atypical (aEPEC) EPEC (8, 21). tEPEC strains are major causative agents of acute diarrhea in infants in developing countries, whereas aEPEC strains affect children and adults worldwide (5,7,9,21). The main difference between tEPEC and aEPEC is the presence of the EPEC adherence factor (EAF) plasmid in tEPEC (8,21). This plasmid encodes the bundle-forming pilus (BFP), which mediates localized adherence to intestinal cells (9), which is an essential property to differentiate tEPEC from aEPEC strains (1,7,21).Formation of the attaching-and-effacing (AE) lesion is the major virulence mechanism of EPEC and an additional virulence property of enterohemorrhagic E. coli (EHEC) strains, a subset of STEC strains (9). This lesion consists of intimate bacterial adherence to the intestinal epithelial cells, cytoskeleton remodeling, and microvillus effacement (9). The genes encoding the AE lesion are located in a pathogenicity island (PAI) known as the locus of enterocyte effacement (LEE) (9). Despite the recognized importance of AE lesion formation, other putative virulence genes among AE-producing E. coli strains have been described. Efa1 (EHEC factor for adherence) is an adhesin originally described in some EHEC strains (16). The efa1 gene is almost identical to lifA, an EPEC gene encoding lymphostatin (LifA) (13). LifA inhibits the proliferation of mitogen-activated lymphocytes and the synthesis of proinflammatory cytokines (13). Efa1/LifA contributes to EPEC adherence to epithelial cells and is critical for intestinal colonization by Citrobacter rodentium, which is an AE lesion-producing bacterial pathogen of mice (12). Although, in the prototype EHEC O157:H7 strain EDL933, efa1 (lifA) lacks the 3Ј region (efaC), the adherence ability of this strain is preserved (20).efa1 (lifA) is outside the LEE and inside PAI O122 (16). This island also harbors genes which are very similar to pagC of Salmonella enterica serovar Typhimurium, sen of Shigella flexneri, and two C. rodentium non-LEE genes, nleB and nleE. PagC is required for bacterial survival within macrophages and is immunogenic to humans, while sen encodes an S. flexneri enterotoxin (10). NleB is linked to colonization and disease in mice (11), and NleE induces polymorphonuclear (PMN) transepithelial migration and is involved in the blockage of 24). Afset et al. (2) found that, of 182 virulence genes searched for among aEPEC strains, 12 were statistically associated with diarrhea, includi...

Four of six adhesin-encoding genes (lpfA, paa, iha, and toxB) from Shiga toxin-producing Escherichia coli strains were detected in typical and atypical enteropathogenic E. coli (EPEC) strains of various serotypes. Although the most prevalent gene was lpfA in both groups, paa was the only potential diarrhea-associated gene in atypical EPEC.

Enteroaggregative Escherichia coli (EAEC) comprises an important diarrheagenic pathotype, while uropathogenic E. coli (UPEC) is the most important agent of urinary tract infection (UTI). Recently, EAEC virulence factors have been detected in E. coli strains causing UTI, showing the importance of these hybrid-pathogenic strains. Previously, we detected an E. coli strain isolated from UTI (UPEC-46) presenting characteristics of EAEC, e.g ., the aggregative adherence (AA) pattern and EAEC-associated genes ( aatA, aap , and pet ). In this current study, we analyzed the whole genomic sequence of UPEC-46 and characterized some phenotypic traits. The AA phenotype was observed in cell lineages of urinary and intestinal origin. The production of curli, cellulose, bacteriocins, and Pet toxin was detected. Additionally, UPEC-46 was not capable of forming biofilm using different culture media and human urine. The genome sequence analysis showed that this strain belongs to serotype O166:H12, ST10, and phylogroup A, harbors the tet, aadA , and dfrA / sul resistance genes, and is phylogenetically more related to EAEC strains isolated from human feces. UPEC-46 harbors three plasmids. Plasmid p46-1 (~135 kb) carries some EAEC marker genes and those encoding the aggregate-forming pili (AFP) and its regulator ( afpR ). A mutation in afpA (encoding the AFP major pilin) led to the loss of pilin production and assembly, and notably, a strongly reduced adhesion to epithelial cells. In summary, the genetic background and phenotypic traits analyzed suggest that UPEC-46 is a hybrid strain (UPEC/EAEC) and highlights the importance of AFP adhesin in the adherence to colorectal and bladder cell lines.