Hypertonic saline up-regulates A3 adenosine receptor expression of activated neutrophils and increases acute lung injury after sepsis*

Abstract

Objective Hypertonic saline resuscitation reduces tissue damage by inhibiting polymorphonuclear neutrophils. Hypertonic saline triggers polymorphonuclear neutrophils to release adenosine triphosphate that is converted to adenosine, inhibiting polymorphonuclear neutrophils through A2a adenosine receptors. polymorphonuclear neutrophils also express A3 adenosine receptors that enhance polymorphonuclear neutrophils functions. Here we investigated whether A3 receptors may diminish the efficacy of hypertonic saline in a mouse model of acute lung injury. Design Randomized animal study and laboratory investigation. Setting University research laboratory. Interventions The effect of A3 receptors on the efficacy of hypertonic saline resuscitation was assessed in A3 receptor knockout and wild-type mice. Animals were treated with hypertonic saline (7.5% NaCl, 4 mL/kg) before or after cecal ligation and puncture, and acute lung injury and mortality were determined. The effect of timing of hypertonic saline exposure on A3 receptor expression and degranulation was studied in vitro with isolated human polymorphonuclear neutrophils. Measurements and main results Treatment of human polymorphonuclear neutrophils with hypertonic saline before stimulation with formyl methionyl-leucyl-phenylalanine inhibited A3 receptor expression and degranulation, whereas hypertonic saline-treatment after formyl methionyl-leucyl-phenylalanine-stimulation augmented A3 receptor expression and degranulation. Acute lung injury in wild-type mice treated with hypertonic saline after cecal ligation and puncture was significantly greater than in wild-type mice pretreated with hypertonic saline. This aggravating effect of delayed hypertonic saline-treatment was absent in A3 receptor knockout mice. Similarly, mortality in wild-type mice with delayed hypertonic saline-treatment was significantly higher (88%) than in animals treated with hypertonic saline before cecal ligation and puncture (50%). Mortality in A3 receptor knockout mice remained only 50% regardless of timing of hypertonic saline administration. Conclusions Polymorphonuclear neutrophils A3 receptors expression determines whether hypertonic saline resuscitation inhibits or aggravates polymorphonuclear neutrophils-induced acute lung injury. These findings suggest that A3 antagonists could improve the efficacy of hypertonic saline resuscitation by reducing side effects in patients whose polymorphonuclear neutrophils are activated before hypertonic saline treatment.

Inhibition of Neutrophils by Hypertonic Saline Involves Pannexin-1, CD39, CD73, and Other Ectonucleotidases

“…Of particular interest is the fact that HS can block PMN activation and reduce host organ damage in animal models of shock (25, 27-31). Based on compelling preclinical evidence, the efficacy and immunomodulatory properties of HS resuscitation were recently tested in a large randomized clinical trial (32-33).…”

“…In this multi-center study, which was carried out in major trauma centers across North America, a 250-ml bolus of 7.5% hypertonic saline (HS) with or without 6% dextran-70 (HSD) was administered to patients in a pre-hospital setting. The trial was stopped prematurely when it became evident that the mortality during the first day after admission was higher in the HS group than in the HSD group and in the control group that received an equal volume of normal saline (31). Nevertheless, the long-term mortality rates and clinical outcome measures did not significantly differ among the three treatment groups.…”

Adenosine arrests breast cancer cell motility by A3 receptor stimulation

“…The antibodies were obtained from Santa Cruz Biotechnology (Santa Cruz, CA; A1 receptor), Abcam (Cambridge, MA; A2a receptor), EMD Millipore (Billerica, MA; A2b receptor), and Alpha Diagnostic International (San Antonio, TX; A3 receptor) and were used according to the manufacturers' directions. These antibodies have been extensively characterized and previously used by our group in several studies [3,[22][23][24][25].…”

Increased Neutrophil Adenosine A3 Receptor Expression Is Associated With Hemorrhagic Shock and Injury Severity in Trauma Patients

“…Recent work has demonstrated that hypertonic saline induces enhanced ATP release from PMNs that can result in PMN inhibition if A2a receptor expression predominates, but may exacerbate excessive PMN activation when A3 receptor expression is present (11-13). Furthermore, in a mouse model of sepsis, delayed resuscitation with HS actually increased A3 receptor expression and abolished the protective effects of hypertonic saline (11). This benefit was restored by the addition of an A3 receptor inhibitor (12).…”