Elastin peptides prepared by alcoholic potassium hydroxide degradation of highly purified fibrous elastin from bovine ligamentum nuchae (c-elastin) were shown to act on the ion channels of human monocytes, aorta smooth muscle cells, and skin fibroblasts. In small amounts (between 0.1 and 1 ,ug/ml), elastin peptides strongly increased calcium influx and inhibited calcium efflux by an apparently calmodulindependent mechanism. They also were shown to increase sodium influx and to decrease rubidium influx in monocyte preparations obtained from human blood. Only the ouabainsensitive portion of rubidium influx was inhibited. The action of elastin peptides is strongly concentration-dependent; the maximal activity observed in the above reactions was <1 /.g/ml. These results suggest that elastin peptides may play a role in the regulation of the biological activity of mesenchymal cells, in the proximity of which they are released by the action of elastase-type enzymes. Such enzymes were demonstrated in aorta smooth muscle cells (membrane-bound serine protease) and in fibroblasts (metalloprotease). Monocytes and polymorphonuclear leukocytes were also shown to carry elastase-type enzymes. The release of peptides from elastin by elastase-type enzymes and the action of such peptides on the ion fluxes through the cell membrane may well be involved in mechanisms of the modulation ofthe phenotype ofmesenchymal cells during aging as well as in the development of age-dependent pathologies such as arterioclerosis.The degradation of elastin by elastases was shown to play an important role in several pathological processes such as the development of emphysema (1-3), of atherosclerosis (4-6), and of a variety of skin diseases (7-9). This action was shown to be due to several proteases of the elastase type, that is, proteases that have an affinity for aliphatic amino acid sequences in hydrophobic proteins. Such enzymes have been described on the surface membrane of aorta smooth muscle cells (SMC) (10)(11)(12); in fibroblasts obtained from human skin, chicken embryo, pig aorta adventitia, and human vulva (13-15); and also in monocytes and macrophages (16). Platelets (17-19) and leukocytes (20, 21) also have been shown to carry a potent elastase-type protease.All of these enzymes, although of different nature (metalloprotease or seine protease), are able to attack elastin fibers and release soluble peptides. It also has been shown that soluble elastin peptides, such as a-elastin prepared by oxalic acid degradation (22) Here we report on the effect of elastin peptides on ion fluxes in fibroblasts and SMC as well as in human bloodderived mononuclear cells.
MATERIALS AND METHODSPatients. Monocytes were obtained from 20 middle-aged healthy men (age 25-52 years) after informed consent. The selection of the subjects was based on the following criteria: good physical and mental health confirmed by clinical, radiological, and biological examinations.Monocytes were separated by Ficoll/Hypaque gradient centrifugation without any modificat...
The age-dependent alterations of phagocytosis and age-dependent cell change (ADCC) activity through Fey receptors of human monocyte monolayers using anti-D human IgG-coated 51Cr-labeled human red blood cells were determined. 40 healthy aged subjects of both sexes (age: 60–85 years) and 20 healthy young people of both sexes (age: 18–25 years) were studied. The phagocytosis increased significantly with aging in both sexes, whereas a decrease in ADCC activity was found.
Angiotensin II (Ang II) is able to induce free radical generation in neutrophils, which is more elevated in neutrophils of patients with hypercholesterolemia (HC). In addition, the signal processing through angiotensin I (Ang I) receptors is altered. In present study, we compared the Ang II-triggered free radical generation of neutrophils obtained from patients with relatively isolated forms of metabolic syndrome (MS) with membrane-bound cholesterol content and membrane fluidity. We determined the enhancement of Ang II-induced superoxide anion and leukotriene C(4) (LTC(4)) generation, membrane fluidity and cell-bound cholesterol content of neutrophils obtained from 12 control subjects, 11 patients with obesity (Ob), 10 patients with type 2 diabetes mellitus (t2-DM) and 12 patients with HC. The alteration of signal processing was studied after preincubation with different inhibiting drugs. Superoxide anion, LTC(4) production and membrane rigidity were increased in the following order: control < Ob < t2-DM < HC. Both Ang II-induced superoxide anion and LTC(4) generation were decreased in control cells by pertussis toxin and fluvastatin (Flu), whereas in each patient group, mepacrin, verapamil and Flu were effective, suggesting alterations in signal pathways, which may be attributed to isoprenylation. The enhancement of superoxide anion and LTC(4) generation correlated significantly with membrane rigidity, independently from the experimental groups and membrane-bound cholesterol content. Membrane rigidity of neutrophils, obtained from patients with MS, plays a role in Ang II-induced free radical generation independent of intracellular cholesterol homeostasis.
Met-enkephalin (ME) exerts a bimodal effect on functional activities of rat peritoneal macrophages (PM); in a range of low concentration (10(-9)-10(-7)M) antibody dependent cellular cytotoxicity (ADCC) was markedly stimulated with a simultaneous decrease of Fc gamma receptor (Fc gamma R) medicated phagocytosis while the opposite was observed at 10(-6)-10(-5)M concentrations. Studying the possible underlying mechanism(s) the followings were recorded: (1) ME in all applied concentrations induced an early Na+ influx which was followed by a Ca2+ efflux in the range of low concentrations. In the range of high concentrations Na+ influx was accompanied by a Ca2+ influx. (2) ME at 10(-8) M concentration induced a rise in cGMP level with a plateau in the 60-120th min of incubation. This effect was prevented by 10(-5) M of naloxone. At 10(-6) M concentration a transient rise of cAMP level was recorded which was not affected by naloxone. (3) Verapamil in 10(-6) M abolished both the Ca2+ influx and the rise in cAMP level induced by 10(-6)-10(-5) M ME but not the rise in cGMP level induced by lower ME concentrations. (4) cAMP elevation by high ME concentrations was abolished by enkephalinase inhibitory puromycin. (5) PM-enkephalinase as assessed by the cleavage of fluorogenic substrate L-alanine beta naphthylamide (ABNA), was inhibited by 10(-6)-10(-5) M of ME. This inhibition was abolished by verapamil, but not affected by naloxone. In the range of low concentrations ME appears to act on specific delta opioid receptors and its action is positively coupled to guanylate cyclase. In relatively higher concentrations ME-action is not mediated by specific delta opioid receptors and it appears to involve Ca2+ influx, adenylate cyclase activation as well as the processing of hormone by PM-enkephalinase.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.