Background
Cardiac injury and dysfunction are contributors to disease progression and mortality in sepsis. This study evaluated the cardiovascular role of intrinsic A&sub2;A adenosine receptor (A&sub2;AAR) activity during lipopolysaccharide (LPS)-induced inflammation.
Conclusions
These experimental data suggest that preservation of A&sub2;AAR functionality might provide therapeutic benefit in human sepsis.
Methods
We assessed the impact of 24 h of LPS challenge (20 mg/kg, IP) on cardiac injury, coronary function and inflammatory mediator levels in Wild-Type (WT) mice and mice lacking functional A&sub2;AARs (A&sub2;AAR KO).
Results
Cardiac injury was evident in LPS-treated WTs, with ~7-fold elevation in serum cardiac troponin I (cTnI), and significant ventricular and coronary dysfunction. Absence of A&sub2;AARs increased LPS-provoked cTnI release at 24 h by 3-fold without additional demise of contraction function. Importantly, A&sub2;AAR deletion per se emulated detrimental effects of LPS on coronary function, and LPS was without effect in coronary vessels lacking A&sub2;AARs. Effects of A&sub2;AAR KO were independent of major shifts in circulating C-reactive protein (CRP) and haptoglobin. Cytokine responses were largely insensitive to A&sub2;AAR deletion; substantial LPS-induced elevations (up to 100-fold) in IFN-γ and IL-10 were unaltered in A&sub2;AAR KO mice, as were levels of IL-4 and TNF-α. However, late elevations in IL-2 and IL-5 were differentially modulated by A&sub2;AAR KO (IL-2 reduced, IL-5 increased). Data demonstrate that in the context of LPS-triggered cardiac and coronary injury, A&sub2;AAR activity protects myocardial viability without modifying contractile dysfunction, and selectively modulates cytokine (IL-2, IL-5) release. A&sub2;AARs also appear to be targeted by LPS in the coronary vasculature. Conclusions: These experimental data suggest that preservation of A&sub2;AAR functionality might provide therapeutic benefit in human sepsis.