A2A Adenosine Receptors Regulate Multiple Organ Failure After Hemorrhagic Shock in Mice

Abstract

Trauma hemorrhagic shock (T/HS) is a clinical condition that causes multiple organ failure that needs rapid intervention. Restricted oxygen at the cellular level causes inflammation and subsequent cell death. Adenosine triphosphate is the universal intracellular energy currency and an important extracellular inflammatory signaling molecule. Adenosine, an endogenous nucleotide formed as a result of the breakdown of adenosine triphosphate, is also released during T/HS. Adenosine binds to four G protein–coupled receptors (A1R, A2a, A2b, A3R) called adenosine receptors or P1 receptors. In the present study, we evaluated the effect of activation, inactivation, and genetic absence of A2aR (A2aR−/− mice) on T/HS-induced multiple organ failure. Wild-type mice were pretreated (30 min before shock induction) with an agonist or antagonist and then subjected to T/HS by withdrawing arterial blood and maintaining the blood pressure between 28 and 32 mm Hg. A2aR−/− mice were subjected to T/HS in the absence of pharmacologic treatment. Neutrophil sequestration was assessed by detecting myeloperoxidase, and Evans blue dye (EBD) method was used to analyze lung permeability. Blood and lung inflammatory cytokine levels were determined by sandwich enzyme-linked immunosorbent assay. The liver enzymes aspartate aminotransferase and alanine aminotransferase were determined spectrophotometrically from plasma. Activation of the apoptotic cascade was evaluated using a mouse apoptosis array. Our results demonstrate that the selective A2aR agonist CGS21680 decreases lung neutrophil sequestration, lung proinflammatory cytokines IL-6 and TNF-α, and bronchoalveolar lavage EBD. Pretreatment with the selective antagonist ZM241385 and genetic blockade in A2aR−/− mice increased neutrophil sequestration, proinflammatory cytokine levels, and bronchoalveolar lavage fluid EBD. The myeloperoxidase level in the lung was also increased in A2aR−/− mice. We observed that antiapoptotic markers decreased significantly with the absence of A2aR in the lung and spleen after T/HS. In conclusion, our data demonstrate that activation of A2aR regulates organ injury and apoptosis in the setting of T/HS.

Adenosine Influences Foxp3 Expression of Tregs via the A2ar/Creb Pathway in a Mouse Model of Sepsis

“…The ability to block A2aR to improve survival in a CLP model of sepsis has been reported widely (13,14,41). As in previous studies, we found that the blockade of A2aR improved survival and suppressed Foxp3 expression (14).…”

Adenosine metabolized from extracellular ATP ameliorates organ injury by triggering A2BR signaling

“…The mice were given anesthesia using 1% isoflurane and their rectal temperature was maintained between 36.5 and 37.5 °C using a feedback-controlled homeothermic blanket heating system (Sumno-suite, Kent Scientific). Hemorrhagic shock was induced using a fixed-pressure model [ 34 ] as described in the Additional data. Initially, a midline laparotomy of 2 cm was performed on the anesthetized mice, which was later closed with a 4 − 0 silk suture (034902, Covetrus, USA).…”

“…Briefly, after a small incision a syringe with a 23G needle filled with 1 ml of sterile saline was inserted into the trachea. After centrifugation (1500 x g for 15 min at 4 °C) the supernatant was used for the assays [ 34 ]. ATP (ab83355, Abcam, USA) and cAMP (KGE012B, R&D Systems, USA) in BALF were measured by a colorimetric assay.…”

“…The supernatant of BALF was assayed at 620 nm spectrophotometrically. The amount of Evans blue dye in the BALF was then expressed as a proportion of the amount in the plasma [ 5 , 34 ].…”

“…The A 2B R is expressed on many immune and non-immune cell types, and in general, it has anti-inflammatory and tissue restorative functions [ 6 , 20 – 33 ]. We have previously shown that the A 2A R has a protective role against organ injury after T/HS [ 5 , 6 , 34 ]. However, the role of the A 2B R and upstream CD39 and CD73 have not been explored.…”