916. Adenosine A2A Receptor Agonists Reduce Recurrence and Late Mortality in Clostridium difficile-infected Mice treated with Vancomycin
Session: Poster Abstract Session: Bacterial Pathogenesis
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Clostridium difficile infection (CDI) is characterized by intense intestinal and systemic inflammatory reactions, especially in moderate to severe disease.  Previous studies have shown that A2A adenosine receptor (A2AAR) activation was associated with decreased production of inflammatory cytokines, prevention of C. difficile toxin A-induced enteritis and, in combination with antibiotics, increased survival from sepsis in mice. We investigate whether A2AAR agonists improve outcomes in the murine model of CDI. 

Methods: C57BL/6 mice, 8-wk old, were pretreated with an antibiotic cocktail (vancomycin [Vanc], colistin, gentamicin, metronidazole, clindamycin) and infected with VPI 10463 (105/mouse). Mice (4-6/group/experiment; 3 experiments) were treated with either Vanc (50 mg/kg/day orally for 3 days) alone, A2AAR agonist ATL 370 (1-10 ng/Kg/min subcutaneously by Alzet pump for 7 or 14 days) alone, or both and monitored for weight loss, diarrhea, and mortality. Moribund mice were euthanized. Cecal and colonic tissues were harvested for histopathology.

Results: Infected, untreated mice lost weight, developed diarrhea and had mortality rates of 50-60% (deaths starting at day 3 post-infection). Infected, Vanco-treated mice had minimal weight loss and diarrhea but mortality of 80-100% (deaths starting at day 8 post-infection). Infected mice treated with ATL 370 alone had 80-100% mortality.  Infected mice treated with both Vanc and ATL 370 (1 ng/kg/min) had minimal weight loss and long-term mortality of 40-60%. No differences in outcomes were seen when the duration (7 vs 14 days) and timing (day 1 or 4 post-infection) of ATL 370 administration were varied.  ATL 370 tended to improve histopathology scores in treated mice but the differences were not statistically significant.

Conclusion:  In a murine model of CDI, Vanc treatment resulted to reduced weight loss and diarrhea during acute infection, but was associated with high recurrence and late-onset death, with overall mortality being worse than untreated infected controls.  The administration of an A2AAR agonist prevented the late mortality associated with Vanc use, suggesting a possible benefit of A2AAR agonists in the management of CDI to prevent recurrent disease and improve survival.


Subject Category: B. Bacterial pathogenesis, studies in animal models, molecular pathogenicity

Yuesheng Li, MD, PhD1, Glynis L. Kolling, PhD1, Robert A. Figler, PhD2,3, Jayson Rieger, PhD3, Ralph W. Stevenson, PhD3, Joel Linden, PhD4, Richard Guerrant, MD1 and Cirle Alcantara Warren, MD1, (1)Division of Infectious Disease and International Health, University of Virginia, Charlottesville, VA, (2)Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, (3)Dogwood Pharmaceuticals, Inc., New Haven, CT, (4)Division of Inflammation and Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA

Disclosures:

Y. Li, None

G. L. Kolling, None

R. A. Figler, Dogwood Pharmaceuticals: Employee, Salary

J. Rieger, Dogwood: Employee, Salary

R. W. Stevenson, Dogwood: Employee, Salary

J. Linden, Forest Labs (ower of Dogwood Therapeutics): Scientific Advisor, Consulting fee

R. Guerrant, None

C. A. Warren, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.