β-chemokine function in experimental lung ischemia-reperfusion injury

Background Although chemokines are functionally important in models of ischemia-reperfusion injury, little is known about their role in lung ischemia-reperfusion injury (LIRI). This study examined the role of the β-chemokines, macrophage inflammatory protein (MIP)-1α, monocyte chemoattractant protein (MCP)-1, and regulated upon activation normal T cells expressed and secreted (RANTES) in LIRI. Methods Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received anti–MIP-1α, anti–MCP-1, or anti-RANTES antibodies before reperfusion. Changes in lung vascular permeability were measured with iodine 125–labeled bovine serum albumin. Neutrophil accumulation in the lung parenchyma was determined by myeloperoxidase activity, and bronchoalveolar lavage was performed to measure leukocyte cell counts. Western blots, Northern blots, and ribonuclease protection assays assessed β-chemokine messenger RNA and protein levels. Results Animals receiving anti–MIP-1α demonstrated reduced vascular permeability compared with controls (p< 0.001). Attenuation of permeability was less dramatic in animals treated with anti–MCP-1 and anti-RANTES antibody, which demonstrated permeability decreases of 15% and 16%, respectively (p< 0.02). Lung neutrophil accumulation was reduced in animals receiving anti–MIP-1α antibody (p< 0.005) but was unchanged in animals receiving either anti–MCP-1 or anti-RANTES. Bronchoalveolar lavage leukocyte content was also reduced by treatment with anti–MIP-1α (p< 0.003) and was unchanged in anti–MCP-1–treated and anti-RANTES–treated animals. MIP-1α treatment decreased tumor necrosis factor-α messenger RNA in injured left lungs. Conclusions MIP-1α is functionally significant in the development of LIRI. It likely exerts its effects in part by mediating the expression of proinflammatory and antiinflammatory cytokines and influencing tissue neutrophil recruitment. MCP-1 and RANTES seem to play relatively minor roles in the development of direct LIRI.