Development of a High-Throughput Urosepsis Mouse Model

by Selleckchem | Sep 11 2023

Murine sepsis models are typically polymicrobial, and are associated with high mortality. We aimed to develop a high-throughput murine model that mimics a slow-paced, monomicrobial sepsis originating from the urinary tract. A total of 23 male C57Bl/6 mice underwent percutaneous insertion of a 4 mm catheter into the bladder using an ultrasound-guided method, previously developed by our group. The following day, Proteus mirabilis (PM) was introduced percutaneously in the bladder in three groups: g1-50 µL 1 × 108 CFU/mL solution (n = 10); g2-50 µL 1 × 107 CFU/mL solution (n = 10); and g3 (sham mice)-50 µL sterile saline (n = 3). On day 4, mice were sacrificed. The number of planktonic bacteria in urine, adherent to catheters, and adherent to/invaded into the bladder and spleen was assessed. Cell-free DNA, D-dimer, thrombin-antithrombin complex (TAT), and 32 pro-/anti-inflammatory cytokines/chemokines were quantified in the blood. All mice survived the 4 day postinterventional period. Mean weight loss was 11% in g1, 9% in g2, and 3% in the control mice. Mean urine CFU counts were highest in group 1. All catheters showed high catheter-adhered bacterial counts. Of the infected mice, 17/20 had CFU counts in the splenic tissue, indicating septicemia. Plasma levels of cell-free DNA, D-dimer, and the proinflammatory cytokines IFN-γ, IL-6, IP-10, MIG, and G-CSF were significantly elevated in infected mice versus controls. We present a reproducible, monomicrobial murine model of urosepsis that does not lead to rapid deterioration and death, and is useful for studying prolonged urosepsis.

Comments:

Your study aimed to develop a murine model that mimics a slow-paced, monomicrobial sepsis originating from the urinary tract. In this study, 23 male C57Bl/6 mice were used, and a catheter was percutaneously inserted into their bladders using an ultrasound-guided method. The following day, Proteus mirabilis (PM), a bacterium commonly associated with urinary tract infections, was introduced percutaneously into the bladder in three different groups: g1 received a 50 µL solution containing 1 × 108 CFU/mL of PM (n = 10), g2 received a 50 µL solution containing 1 × 107 CFU/mL of PM (n = 10), and g3 (sham mice) received a 50 µL sterile saline solution (n = 3). On day 4, the mice were sacrificed, and various assessments were performed.

The study evaluated the number of planktonic bacteria in the urine, as well as bacteria adherent to the catheters, bladder, and spleen. Additionally, several biomarkers and cytokines were measured in the blood, including cell-free DNA, D-dimer, thrombin-antithrombin complex (TAT), and 32 pro-/anti-inflammatory cytokines/chemokines.

The results showed that all mice survived the 4-day post-interventional period, indicating that the model did not lead to rapid deterioration and death. The mean weight loss was 11% in g1, 9% in g2, and 3% in the control mice. The mean urine colony-forming unit (CFU) counts were highest in group 1, indicating a higher bacterial load in the bladder.

Furthermore, all catheters showed high bacterial counts, indicating bacterial adherence to the catheter surfaces. Among the infected mice, 17 out of 20 had CFU counts in the splenic tissue, suggesting the presence of septicemia.

In terms of biomarkers and cytokines, plasma levels of cell-free DNA, D-dimer, and several pro-inflammatory cytokines (IFN-γ, IL-6, IP-10, MIG, and G-CSF) were significantly elevated in infected mice compared to the control group. This suggests an immune response and inflammation associated with the urosepsis model.

Overall, the study successfully developed a reproducible murine model of monomicrobial urosepsis originating from the urinary tract. The model did not result in rapid deterioration and death, allowing for the study of prolonged urosepsis. The findings provide valuable insights into the mechanisms and biomarkers associated with urosepsis in a controlled experimental setting.