Blocking CCL5 with a neutralizing monoclonal antibody attenuates neutrophil and macrophage infiltration in the ischemic site and improves survival and cardiac function after coronary ligation in mice (15). Therefore , development of new treatment strategy for this life-threatening disease is required. Hypoxia due to marked reduction of blood supply impairs barrier function of endothelial cells. As a result, vessel permeability is enhanced and leukocyte infiltration through vessel walls is subsequently augmented (1, 2). Injured or dead cells and damaged extracellular matrix due to prolonged hypoxia release danger associated molecular patterns (DAMPs) which activate innate immune system to release inflammatory mediators such as cytokines, chemokines and PSI-6206 13CD3 adhesive molecules via pattern recognition receptors (PRRs) including toll-like receptors (TLRs) and subsequently recruit immune cells into the infarcted site (2, 3). DAMPs also trigger the enhance cascade which induces further chemotaxis (2, 4). Recovery of blood flow during this period induces reperfusion injury because the sudden supply of oxygen in this scenario with excess succinate released by damaged cells allows the reverse flow of electrons through complex II of the electron transport chain, succinate dehydrogenase, such that reactive oxygen species (ROS) are generated in excess (5). This ROS production amplifies tissue damage and additional activation of the enhance pathway (1, 2). When blood supply to the tissue is markedly reduced, neutrophils are initially recruited into the IL-15 ischemic zone. They release proteolytic enzymes and more ROS to perpetuate local cytotoxicity. They also secrete further inflammatory mediators and induce subsequent monocyte migration into the ischemic site (2, three or more, 6, 7). Humans and mice possess at least two monocyte subsets. The first is the classical inflammatory monocyte which is typically identified as CD14+CD16monocyte in humans and as Ly6Chighmonocytes in mice (which like human monocytes are CD14+CD16(8). The other subset is the non-classical inflammatory monocyte, which is typically identified as CD14lowCD16+in humans and Ly6Clowmonocyte in mice (9). These human and mouse monocyte subsets possess gene expression similarities (8, 10). After coronary ligation PSI-6206 13CD3 of mice, classical monocytes are recruited to the infarcted site and perform proteolytic and inflammatory activity initially. When recovery goes well, these monocytes differentiate into cells that at least transiently resemble non-classical monocytes that in turn become repair-promoting macrophages (11, 12). In skeletal muscle injury, blockade of monocyte recruitment prevents effective recovery (11). Often , however , recruited monocytes develop detrimental phenotypes, particularly when their recruitment leads to the replacement of cardiac resident macrophages which have inherent regenerative potential (13). In this PSI-6206 13CD3 case, inhibition of monocyte recruitment preserves the population of those resident macrophages and attenuates cardiomyocyte injury in mice (13) and chronic heart failure (14). Chemokines are a group of chemotactic heparin-binding cytokines. Many chemokines like CCL2, which attracts CCR2-expressing classical monocytes, are released from the infarcted site and play a critical role in disease processes. Among the many chemokines characterized is CCL5 (also known as RANTES: regulated on activation, normal To cell expressed and secreted). CCL5 recruits monocytes, neutrophils and lymphocytes through binding to multiple chemokine receptors, CCR1, CCR3 and CCR5. Blocking CCL5 with a neutralizing monoclonal antibody attenuates neutrophil and macrophage infiltration in the ischemic site and improves survival and cardiac function after coronary ligation in mice (15). However , Ccl5/mice show a decrease in antigen-specific T cell proliferation and production of interferon gamma (IFN-) and IL-2 by T cells (16), and they are immune compromised due to delayed viral clearance (17). Therefore , direct inhibition of CCL5 in a therapeutic setting may have an negative effect on immune response against pathogen contamination. Moreover, CCL5 is reported to be required for ischemia-induced angiogenesis (18), which could limit the healing effect of CCL5 inhibiting therapy. Thus, if it were possible to selectively affect certain activities of CCL5, therapeutic potential of focusing on the role of CCL5 in cardiovascular disease would be greater. A recent newspaper by Alardet al. raises such a possible, more.