Pharmacological modulation of C‐X‐C motif chemokine receptor 4 influences development of acute respiratory distress syndrome after lung ischaemia–reperfusion injury

Abstract

Activation of C-X-C motif chemokine receptor 4 (CXCR4) has been reported to result in lung protective effects in various experimental models. The effects of pharmacological CXCR4 modulation on the development of acute respiratory distress syndrome (ARDS) after lung injury, however, are unknown. Thus, we studied whether blockade and activation of CXCR4 influences development of ARDS in a unilateral lung ischaemia-reperfusion injury rat model. Anaesthetized, mechanically ventilated animals underwent right lung ischaemia (series 1, 30 minutes; series 2, 60 minutes) followed by reperfusion for 300 minutes. In series 1, animals were treated with vehicle or 0.7 μmol/kg of AMD3100 (CXCR4 antagonist) and in series 2 with vehicle, 0.7 or 3.5 μmol/kg ubiquitin (non-cognate CXCR4 agonist) within 5 minutes of reperfusion. AMD3100 significantly reduced PaO /FiO ratios, converted mild ARDS with vehicle treatment into moderate ARDS (PaO /FiO ratio<200) and increased histological lung injury. Ubiquitin dose-dependently increased PaO /FiO ratios, converted moderate-to-severe into mild-to-moderate ARDS and reduced protein content of bronchoalveolar lavage fluid (BALF). Measurements of cytokine levels (TNFα, IL-6, IL-10) in lung homogenates and BALF showed that AMD3100 reduced IL-10 levels in homogenates from post-ischaemic lungs, whereas ubiquitin dose-dependently increased IL-10 levels in BALF from post-ischaemic lungs. Our findings establish a cause-effect relationship for the effects of pharmacological CXCR4 modulation on the development of ARDS after lung ischaemia-reperfusion injury. These data further suggest CXCR4 as a new drug target to reduce the incidence and attenuate the severity of ARDS after lung injury.

Effects of cognate, non-cognate and synthetic CXCR4 and ACKR3 ligands on human lung endothelial cell barrier function

“…Thus, we performed post-treatment experiments and detected that activation of CXCR4 after thrombin-exposure of hPPAEC and HULEC5a cells attenuates thrombin-mediated impairment of lung endothelial barrier function. These findings support the concept that CXCR4 agonists have therapeutic potential to limit thrombin-mediated pulmonary vascular leakage, which likely contributed to lung protective effects of CXCR4 agonists that have been observed in various models when administered after the insult [ 15 , 17 , 18 , 21 , 43 ].…”

Natural and engineered chemokine (C-X-C motif) receptor 4 agonists prevent acute respiratory distress syndrome after lung ischemia–reperfusion injury and hemorrhage

“…These CXCL12 variants were chosen based on their efficacy and potency to protect lung endothelial cell barrier function in vitro, and based on their distinct physicochemical properties, such as resistance to proteolytic cleavage and heparan sulfate proteoglycan binding affinity, which could result in altered functional outcomes after administration of the proteins in vivo 9,20,21 . www.nature.com/scientificreports/ The effects of the non-cognate CXCR4 agonist ubiquitin on ARDS development in the present study are consistent with our previous observations 2, 5,6,10 . Although a synthetic CXCL12 analogue and wild-type CXCL12 have been reported to attenuate lipopolysaccharide and oleate induced lung injury, their effects on lung function, i.e.…”

“…The findings from the present study demonstrate that wild-type CXCL12, CXCL12 1 and CXCL12 2 are equally efficacious but more potent than ubiquitin to preserve lung function in our ARDS model. These observations are in agreement with the previously described detrimental effects of the CXCR4 antagonist AMD3100 on lung function after isolated lung ischemia-reperfusion injury, and with the lower affinity of ubiquitin for CXCR4, when compared with the affinity of CXCL12 5,23 . The observation that CXCL12 (3-68) did not affect ARDS development is consistent with the loss of function of N-terminal truncated CXCL12 in other assay systems 9,24,25 and documents specificity of the effects of CXCL12, CXCL12 1 and CXCL12 2 .…”

“…In series 3 animals were treated with vehicle (n = 5) or with 0.14 μmol/ kg of CXCL12 (n = 4) or the engineered variants CXCL12 1 (n = 3), CXCL12 2 (n = 4) and CXCL12 K27A/R41A/ R47A (n = 3). The dosing of the CXCR4 agonists was selected based on our previous observations in other animal models 5,10,43 .…”

“…The slides were examined under a light microscope by 4 investigators who were blinded as to the identity of the specimens. Histopathology was assessed using a previously described lung injury score (LIS) 5,44 . In brief, each investigator rendered a score of 0 (no damage) to 4 (maximal damage) based on the following criteria: (1) alveolar congestion, (2) presence of hemorrhage, (3) interstitial edema, (4) alveolar wall thickness, (5) infiltration of polymorphonuclear neutrophils (PMN) in the vessel wall and (6) infiltration of PMN in the alveoli.…”