Monocyte chemoattractant protein-1 deficiency is protective in a murine stroke model

Inflammatory processes have been implicated in the pathogenesis of brain damage after stroke. In rodent stroke models, focal ischemia induces several proinflammatory chemokines, including monocyte chemoattractant protein-1 (MCP-1). The individual contribution to ischemic tissue damage, however, is largely unknown. To address this question, the authors subjected MCP-1-deficient mice (MCP-1−/−) to permanent middle cerebral artery occlusion (MCAO). Measurement of basal blood pressure, cerebral blood flow, and blood volume revealed no differences between wild-type (wt) and MCP-1−/− mice. MCAO led to similar cerebral perfusion deficits in wt and MCP-1−/− mice, excluding differences in the MCA supply territory and collaterals. However, compared with wt mice, the mean infarct volume was 29% smaller in MCP-1−/− mice 24 hours after MCAO (P = 0.022). Immunostaining showed a reduction of phagocytic macrophage accumulation within infarcts and the infarct border in MCP-1−/− mice 2 weeks after MCAO. At the same time point, the authors found an attenuation of astrocytic hypertrophy in the infarct border and thalamus in MCP-1−/− mice. However, these effects on macrophages and astrocytes in MCP-1−/− mice occurred too late to suggest a protective role in acute infarct growth. Of note: at 6 hours after MCAO, MCP-1−/− mice produced significantly less interleukin-1β in ischemic tissue; this might be related to tissue protection. The results of this study indicate that inhibition of MCP-1 signaling could be a new acute treatment approach to limit infarct size after stroke.