RESUMO
In asymptomatic bacteriuria (ABU), bacteria colonize the urinary tract without provoking symptoms. Here, we compared the virulence properties of a collection of ABU Escherichia coli strains to cystitis and pyelonephritis strains. Specific urinary tract infection (UTI)-associated virulence genes, hemagglutination characteristics, siderophore production, hemolysis, biofilm formation, and the ability of strains to adhere to and induce cytokine responses in epithelial cells were analyzed. ABU strains were phylogenetically related to strains that cause symptomatic UTI. However, the virulence properties of the ABU strains were variable and dependent on a combination of genotypic and phenotypic factors. Most ABU strains adhered poorly to epithelial cells; however, we also identified a subgroup of strongly adherent strains that were unable to stimulate an epithelial cell IL-6 cytokine response. Poor immune activation may represent one mechanism whereby ABU E. coli evade immune detection after the establishment of bacteriuria.
Assuntos
Bacteriúria/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Infecções Urinárias/microbiologia , Fatores de Virulência/biossíntese , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Aderência Bacteriana , Biofilmes/crescimento & desenvolvimento , Cistite/microbiologia , Citocinas/metabolismo , Células Epiteliais/microbiologia , Escherichia coli/isolamento & purificação , Proteínas de Escherichia coli/biossíntese , Proteínas de Escherichia coli/genética , Feminino , Hemaglutinação , Hemólise , Humanos , Masculino , Pessoa de Meia-Idade , Pielonefrite/microbiologia , Sideróforos/biossíntese , Fatores de Virulência/genéticaRESUMO
A series of N-heterocyclic dipeptide aldehydes 4-13 have been synthesised and evaluated as inhibitors of ovine calpain 1 (o-CAPN1) and ovine calpain 2 (o-CAPN2). 5-Formyl-pyrrole 9 (IC(50) values of 290 and 25nM against o-CAPN1 and o-CAPN2, respectively) was the most potent and selective o-CAPN2 inhibitor, displaying >11-fold selectivity. The amino acid sequences of o-CAPN1 and o-CAPN2 have been determined. Because of the lack of available structural information on the ovine calpains, in silico homology models of the active site cleft of o-CAPN1 and o-CAPN2 were developed based on human calpain 1 (h-CAPN1) X-ray crystal structure (PDB code 1ZCM). These models were used to rationalise the observed SAR for compounds 4-13 and the selectivity observed for 9. The o-CAPN2 selective inhibitor 9 (CAT0059) was assayed in an in vitro ovine lens culture system and shown to successfully protect the lens from calcium-induced opacification.
