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Fibroblast Chemotaxis Induction by Human Recombinant Interleukin-4

Interleukin-4 is a T lymphocyte- and mast cell-derived cytokine with pleiotropic properties with biological effects on a variety of target cells including B and T lymphocytes, macrophages, hematopoietic cells, mast cells, and fibroblasts. In addition to the proliferation effect of IL-4 on fibroblasts, which has been previously described, in this report the chemotactic properties of IL-4 for fibroblasts is described. Human recombinant IL-4 induced the chemotactic migration of dermal fibroblasts in vitro in modified Boyden-type chambers at concentrations between 10(-12) and 10(-11) M. The chemotactic activity of IL-4 was neutralized by anti-human recombinant IL-4 IgG antibodies. Oligopeptides representing the complete deduced amino acid sequence of human IL-4 were synthesized by the Merrifield technique and tested for their ability to induce fibroblast chemotaxis. Two peptides representing residues 70-88 and 89-122 induced fibroblast migration. Peptide 70-88 was the more potent of the two causing chemotaxis of fibroblasts at 10(-8)-10(-6) M while peptide 89-129 induced migration at 10(-7)-10(-5) M. Although the mechanism by which IL-4 and these two peptides induce fibroblast chemotaxis is unknown, each of these three compounds were able to chemotactically desensitize fibroblasts to the chemotactic effects of the other two but not to a structurally unrelated chemotactic cytokine, transforming growth factor beta-1. These studies suggest that IL-4 might function in vivo to induce the accumulation of fibroblasts at sites of tissue injury, inflammatory and immune reactions in which T lymphocytes and mast cells participate.

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Cigarette Smoke Inhibits Human Bronchial Epithelial Cell Repair Processes

By interfering with the ability of airway epithelial cells to support repair processes, cigarette smoke could contribute to alterations of airway structures and functions that characterize chronic obstructive pulmonary disease (COPD). The current study assessed the ability of cigarette smoke extract (CSE) to alter human airway epithelial cell chemotaxis, proliferation, and contraction of three-dimensional collagen gels, a model of extracellular matrix remodeling. The volatile components contained in cigarette smoke, acetaldehyde and acrolein, were able to inhibit all three processes. Nonvolatile components contained within lyophilized CSE also inhibited chemotaxis but displayed no activity in the other two bioassays. CSE also inhibited the ability of airway epithelial cells to release transforming growth factor (TGF)- β and fibronectin. Exogenous fibronectin was unable to restore epithelial cell contraction of collagen gels. Exogenous TGF- β partially restored the ability of airway epithelial cells to contract collagen gels and to produce fibronectin. This supports a role for inhibition of TGF- β release in mediating the inhibitory effects of cigarette smoke. Taken together, the results of the current study suggest that epithelial cells present in the airways of smokers may be altered in their ability to support repair responses, which may contribute to architectural disruptions present in the airways in COPD associated with cigarette smoking.

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Activation of the Phosphatidylinositol 3-Kinase/Protein Kinase Akt Pathway Mediates Nitric Oxide-Induced Endothelial Cell Migration and Angiogenesis

To test the hypothesis that the phosphatidylinositol 3-kinase (PI3 kinase)/protein kinase Akt signaling pathway is involved in nitric oxide (NO)-induced endothelial cell migration and angiogenesis, we treated human and bovine endothelial cells with NO donors, S-nitroso-l-glutathione (GSNO) and S-nitroso-N-penicillamine (SNAP). Both GSNO and SNAP increased Akt phosphorylation and activity, which were blocked by cotreatment with the PI3 kinase inhibitor wortmannin. The mechanism was due to the activation of soluble guanylyl cyclase because 8-bromo-cyclic GMP activated PI3 kinase and the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-α]quinoxalin-1-one (ODQ) blocked NO-induced PI3 kinase activity. Indeed, transfection with adenovirus containing endothelial cell NO synthase (eNOS) or protein kinase G (PKG) increased endothelial cell migration, which was inhibited by cotransfection with a dominant-negative mutant of PI3 kinase (dnPI3 kinase). In a rat model of hind limb ischemia, adenovirus-mediated delivery of human eNOS cDNA in adductor muscles resulted in time-dependent expression of recombinant eNOS, which was accompanied by significant increases in regional blood perfusion and capillary density. Coinjection of adenovirus carrying dnPI3 kinase abolished neovascularization in ischemic hind limb induced by eNOS gene transfer. These findings indicate that NO promotes endothelial cell migration and neovascularization via cGMP-dependent activation of PI3 kinase and suggest that this pathway is important in mediating NO-induced angiogenesis.

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Leptin Stimulates Rat Aortic Smooth Muscle Cell Proliferation and Migration

Leptin, a peptide secreted from adipose tissue, plays an important role in the regulation of food intake and energy expenditure. In obese patients, plasma leptin levels are elevated and obesity is one of the major risk factors for cardiovascular diseases. Therefore, in this study, we investigated the effect of leptin on vascular smooth muscle cell (VSMC) functions. Cultured rat aortic VSMC expressed 130-kDa short form of leptin receptor. Leptin stimulated both proliferation and migration of VSMC. Leptin stimulated phosphorylation and activation of mitogen-activated protein (MAP) kinases, and also increased phosphatidylinositol (PI) 3-kinase activity. Further, two distinct PI 3-kinase inhibitors, wortmannin and LY294002 inhibited the migratory effect of leptin. These results demonstrate that leptin is a proliferative and migratory factor for VSMC, implying that leptin may play a role in the formation and development of vascular lesions.

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Enhanced migration of fibroblasts derived from lungs with fibrotic lesions

The migration and proliferation of fibroblasts may be important in the pathogenesis  of pulmonary fibrosis.
Considerable data are available on the proliferation of fibroblasts, but very few on their migration.
Methods – The migratory activity of fibroblasts obtained from lung biopsy specimens from 11 patients with idiopathic pulmonary fibrosis (IPF) was studied using a 96-well chemotaxis chamber.
Fibroblasts from eight normal controls, seven patients with interstitial fibrosis associated with a collagen vascular disease (IP-CVD), and 13 patients with sarcoidosis were also examined. Migratory
activity was tested in a serum-free medium in the presence and absence of platelet derived growth factor (PDGF), 30 ng/mL, as a chemoattractant.