Chemoattraction

A number of adipokines are linked to inflammation and immunity (Fig. 1). This includes both leptin and adiponectin, and also a number of other key inflammatory proteins, particularly cytokines and chemokines [1]. The cytokines and chemokines encompass interleukin-1(3 (EL-1 (3), IL-6, DL-10, TNFa, monocyte chemoattractant protein-1 (MCP-1), and macrophage migration inhibitory factor (MIF). Other major inflammation-related adipokines include nerve growth factor (NGF), and acute phase proteins such as serum amyloid A and haptoglobin. In addition, adipocytes secrete plasminogen activator inhibitor-1 (PAI-1), which is an important thrombotic factor as well as an acute phase protein. 

T-cells, representing the adaptive arm of the immune response, also play a critical role in atherogenesis, and enter lesions in response to the chemokines inducible protein-10 (DP-10), monokine induced by DFN-y (MIG), and DFN-inducible T-cell a-chemoattractant (I-TAC), which bind CXCR3 (a chemokine receptor containing two cysteine residues separated by one amino acid), highly expressed by T lymphocytes in the plaque. The... 

The atherosclerotic plaque overexpresses another chemoattractant, eotaxin, that may mediate mast cell... 

Inflammation. Figure 1 Sequence of events in the recruitment of leukocytes in postcapillary venules adjacent to injured tissue. At the site of lesion, diverse reactive substances stimulate the endothelium to produce inflammatory cytokines, chemoattractants and other inflammatory mediators. The cytokine-activated endothelium expresses adhesion molecules that lead to the low affinity interactions between leukocytes and endothelium, which is mediated by selectins and described as rolling. Subsequently integrins mediate the firm adhesion of leukocytes, which allows emigration of the cells from venules into the interstitial compartment. Activated mast cells, PMNs and macrophages secrete cytokines (TNFa), lipid mediators (LTB4) and other inflammatory players (histamine, NO). 

In the interstitium, angiotensin II induces proliferation of mesangial cells and fibroblasts and the synthesis of collagen and other matrix molecules by these cells via the ATI receptor. Moreover, by the concomitant stimulation of chemoattractant cytokines, inflammation is induced. These processes are mediated by endothelin, transforming growth factor(3, and reactive oxygen species, and finally lead to interstitial fibrosis and glomerulosclerosis observed in hypertension and diabetes. 

Cheese Reaction Chemical Chaperone Chemical Library Chemical Neurotransmission Chemoattractant Receptors Chemokine Receptors Chemokines... 

Figure 2. (1) Neutrophils circulating passively in blood capillary. (2) Chemoattractants may be detected by the circulating neutrophils, by the endothelial cells lining the lumen, or both in order that the neutrophils become adhesive. This adhesion is mediated by selectins, a group of cell surface proteins. Neutrophils roll on the surface of the endothelial cells and then actively locomote seeking out spaces between the endothelial cells. (3) The adhesive neutrophils begin to squeeze between endothelial cells. (4) Cells move through the extracellular matrix towards the site of infection. Here adhesion is low and may not be necessary for locomotion. (5) At the site of infection, neutrophils become trapped by increased adhesion where they phagocytose bacteria and liberate the contents of their granules. After Lackie (1982,1986).

These cells respond to a number of different chemoattractants which have specific and distinct receptors on the membrane surface (for recent reviews see Refs. 3 and 4). Such chemoattractants include N-formylpeptides, which are bacterial peptides, and mediators of inflammation such as leukotriene B4, C5a, and platelet activating factor. 

Zink MC, Coleman GD, Mankowski JL, Adams RJ, Tarwater PM, Fox K, Clements JE (2001) Increased macrophage chemoattractant protein-1 in cerebrospinal fluid precedes and predicts simian immunodeficiency virus encephalitis. J Infect Dis 184(8) 1015-1021... 

White FA, Sun J et al (2005b) Excitatory monocyte chemoattractant protein-1 signaling is up-regulated in sensory neurons after chronic compression of the dorsal root ganglion. Proc Natl Acad Sci USA 102(39) 14092-14097... 

Biemacki K, Prat A, Blain M, Antel JP (2001) Regulation of Thl and Th2 lymphocyte migration by human adult brain endothelial cells. J Neuropathol Exp Neurol 60 1127-1136 Bleul CC, Farzan M, Choe H, Parolin C, Clark-Lewis I, Sodroski J, Springer TA (1996a) The lymphocyte chemoattractant SDF-1 is a ligand for LESTR/fusin and blocks HIV-1 entry. Nature 382 829-833... 

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