The effect of MCP-1 depletion on chemokine and chemokine-related gene expression: evidence for a complex network in acute inflammation

The expression of chemokines has been suggested to involve an interdependent network, with the absence of a single chemokine affecting the expression of multiple other chemokines. Monocyte chemoattractant protein (MCP-1), a member of C-C chemokine superfamily, plays a critical role in the recruitment and activation of leukocytes during acute inflammation. To examine the effect of the loss of MCP-1 on expression of the chemokine network, we compared the mRNA expression profiles of MCP-1−/− and wild type mice during the acute inflammatory phase of excisional wounds. Utilizing a mouse cDNA array containing 514 chemokine and chemokine related genes, the loss of MCP-1 was observed to cause a significant upregulation of nine genes (Decorin, Persephin, IL-1β, MIP-2, MSP, IL1ra, CCR5, CCR3, IL-11) and significant downregulation of two genes (CCR4 and CD3Z) in acute wounds. The array data was confirmed by semi-quantitative RT-PCR. The effect of MCP-1 deletion on chemokine expression was further examined in isolated macrophages. Compared to wild type, LPS-stimulated peritoneal macrophages from MCP-1−/− mice showed a significant increase in the expression of RANTES, MIP-1β, MIP-1α and MIP-2 mRNA. The data suggest that loss of a single chemokine perturbs the chemokine network not only in the setting of acute inflammation but even in an isolated inflammatory cell, the macrophage.