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[Experimental urinary tract infection caused by Escherichia coli in diabetic mouse--uroepithelial colonization and
1Department of Urology, Okayama University Medical School.
Abstract:
Relationship between polymorphonuclear leukocyte (PMN) function and susceptibility to infections in diabetic mice was studied. In the experimental urinary tract infections, 6 strains of Escherichia coli with different fimbrial expression and hemolysin production were used. In contrast with non-fimbriated strains, fimbriated strains were more susceptible to phagocytosis by PMN. MS+.MR+ strains, however, showed resistance to intracellular killing by PMN. OEC-709, OEC-716 (MS+.MR+ strains), and OEC-734 (MS+.MR- strains), also showed resistance to the bactericidal activity of the serum. The killing activities of PMN derived from diabetic mice against these 3 strains were significantly lower than those of PMN from normal mice. In normal mice, MS+.MR+ strains showed the strongest colonization ability to the bladder and kidney, whereas MS-.MR- strains showed the weakest ability among the strains. In diabetic mice, the number of bacteria colonizing to the bladder and kidney was higher than that in normal mice, except for one MS-.MR- strain. Significant differences were observed in the strains (OEC-709, 716, 734), in which PMN was concerned strongly in the bacterial killing. Finally, these findings suggest that deterioration of the bactericidal activity of PMN in a diabetic state is involved in increased susceptibility of diabetic mice.
Insights
Diabetic mice exhibit impaired polymorphonuclear leukocyte (PMN) function, increasing susceptibility to bacterial infections like urinary tract infections. This study highlights reduced bacterial killing by PMN in diabetic conditions.
Area of Science:
- Immunology
- Microbiology
- Diabetology
Context:
- Diabetes mellitus is associated with increased infection susceptibility.
- Polymorphonuclear leukocytes (PMNs) are critical for innate immunity against bacterial pathogens.
- Urinary tract infections (UTIs) are common in diabetic patients.
Purpose:
- To investigate the relationship between polymorphonuclear leukocyte (PMN) function and susceptibility to urinary tract infections (UTIs) in diabetic mice.
- To evaluate the impact of bacterial virulence factors (fimbrial expression, hemolysin production) on PMN activity and bacterial colonization in diabetic and normal mice.
Summary:
- Fimbriated Escherichia coli strains were more readily phagocytosed by PMNs, but MS+.MR+ strains resisted intracellular killing.
- Specific bacterial strains (OEC-709, OEC-716, OEC-734) showed resistance to serum bactericidal activity.
- PMNs from diabetic mice demonstrated significantly reduced killing activity against these strains compared to PMNs from normal mice.
- Diabetic mice showed higher bacterial colonization in the bladder and kidney, except for one strain.
- Impaired PMN bactericidal activity in diabetic mice contributes to increased susceptibility to UTIs.
Impact:
- These findings underscore the role of compromised PMN function in the heightened infection risk observed in diabetic individuals.
- Understanding these mechanisms can inform strategies for preventing and managing infections in diabetic patients.
- Highlights the interplay between host immune status, bacterial virulence, and infection outcomes in diabetes.