1. Effects of defensin and lactoferrin on functional activity of endothelial cells in vitro
A V Krylov, E P Kisseleva, G M Aleshina, O V Shamova, V N Kokryakov Bull Exp Biol Med. 2007 Sep;144(3):331-4. doi: 10.1007/s10517-007-0325-2.
We studied the effects of antibacterial peptides and proteins (defensins and lactoferrins) on functional activity of endothelial cells in vitro: proliferative activity and adhesion of human endothelial ECV-304 cells to the matrix were evaluated, alpha-Defensin (NP-2) from rabbit neutrophils, total alpha-defensin (HNP 1-3) from human neutrophils, and lactoferrins from porcine neutrophils and human milk were studied. Defensins stimulated and lactoferrin in doses of 1-10 microg/ml inhibited proliferation and adhesion of endothelial cell. The stimulatory effect of defensins on proliferation and adhesion was reproduced in fibroblast culture. Lactoferrins did not modify proliferation of fibroblasts, but suppressed their adhesion. These data suggest that antibiotic proteins and peptides are prospective objects for the creation of drugs regulating angiogenesis.
2. Dynamic changes in neutrophil defensins during endotoxemia
M E Klut, B A Whalen, J C Hogg Infect Immun. 2001 Dec;69(12):7793-9. doi: 10.1128/IAI.69.12.7793-7799.2001.
Bacterial endotoxin or lipopolysaccharide (LPS) is an important causative agent of sepsis. This study determines the expression of defensins NP-2 and NP-5 and the function of polymorphonuclear leukocytes (PMN) in rabbits treated with LPS. PMN functional activity was assessed by measuring CD18 expression and H(2)O(2) production and by examining the lungs. NP-2 and, to a minor extent, NP-5 of circulating PMN increase during endotoxemia. This early increase is concomitant with neutrophilia and elevated CD18 expression and H(2)O(2) production, as well as with enhanced NP-2 immunoreactivity in pulmonary microvessels. A decline in defensins, shortly after the last LPS treatment, is associated with a decrease in the circulating activated PMN and enhanced immunoreactivity in the inflammatory cells, as well as with lung tissue damage. This study shows that LPS-induced changes in the defensins of circulating PMN correlate with the number and activated condition of these cells and suggests that PMN-derived products implement the inflammatory reaction that leads to lung injury and sepsis.
3. Interaction of macrophage cationic proteins with the outer membrane of Pseudomonas aeruginosa
J G Sawyer, N L Martin, R E Hancock Infect Immun. 1988 Mar;56(3):693-8. doi: 10.1128/iai.56.3.693-698.1988.
The interaction of the polycationic rabbit alveolar macrophage cationic proteins MCP-1 and MCP-2 (or their identical neutrophil equivalents NP-1 and NP-2) with the surface of Pseudomonas aeruginosa was investigated. Both proteins bound avidly to purified lipopolysaccharide, as judged by their ability to competitively displace the probe dansyl polymyxin with 50% inhibition (I50) values of 2 to 3 microM. Similar I50 were measured with dansyl polymyxin as a probe for cell surface binding, suggesting that the initial binding site for MCP-1 and MCP-2 on the surface of cells was lipopolysaccharide. Both MCP-1 and MCP-2 permeabilized outer membranes to the hydrophobic fluorescent probe 1-N-phenylnaphthylamine (NPN). The initial rate of NPN uptake plotted against the concentration of MCP-1 or MCP-2 gave sigmoidal curves, suggesting cooperative permeabilization of the outer membrane. Replotting the data as a Hill plot gave an affinity parameter, S0.5, the concentration of MCP giving a half-maximal increase in the rate of NPN uptake, of 5 and 25 microM for MCP-1 and MCP-2, respectively, and thus subsequent studies concentrated on the more active permeabilizer MCP-1. Permeabilization of outer membranes to NPN was a function of buffer pH, with lower pH considerably favoring the permeabilizing effects of MCP-1. Thin-section electron microscopic visualization of MCP-1-treated cells showed production of extended blebs. Further evidence of an altered cell surface after MCP-1 treatment was obtained by demonstrating that treated unopsonized cells were more efficiently phagocytosed by unelicited rabbit alveolar macrophages. The data overall suggest that macrophage cationic proteins interact with the P. aeruginosa outer membrane in a manner typical of other polycations and suggest that one of their major functions may be to permeabilize the outer membrane.
