Increased elastase and cathepsin G activity in activated lymphocytes from aged patients: role of denutrition and dementia.

Elastase and cathepsin G activities in cell-lysates and in culture supernates of activated human lymphocytes (incubated for 96 h in the presence of 5 microg/ml of phytohemagglutinin with/without 2 microg/ml of elastin peptides) of 25 old, hospitalized patients (average age: 88.48+/-6.81 years), suffering from vascular-type dementia or denutrition were examined, in comparison with samples of 11 young, healthy donors.

[The importance of the Maillard reaction in ophtalmology].

Non enzymatic glycosylation( glycation) of proteins, described by L. C. Maillard in 1912, results in the formation of advanced glycation end products (AGE-s).

[Demonstration of the cytotoxic effect of Advanced Glycation Endproducts (AGE-s)].

Advanced Glycation End-products (AGE-s) were shown to exhibit a number of potentially harmful properties in contact with cells and tissues. As their concentrations increases with age, faster even in hyperglycemic individuals, they are considered important for aging- and age-associated pathologies, especially for athero-arteriosclerosis and type II diabetes. We describe here the methods used for the demonstration of a direct cytotoxicity of several AGE-products when added to human skin fibroblast cultures.

Effect of cellular aging on collagen biosynthesis: I. Methodological considerations and pharmacological applications.

The study of the age and passage dependent modifications of collagen biosynthesis requires a simple, rapid and reproducible procedure adaptable to serial cell cultures. To make such a method comparable to other methods of collagen determination, we calibrated a colorimetric procedure both by hydroxyproline (HYP) determinations and in terms of collagen concentration. For collagen types I and IV, widely different slopes were obtained with the colorimetric procedure.

Pharmacological properties of rhamnose-rich polysaccharides, potential interest in age-dependent alterations of connectives tissues.

Rhamnose-rich oligo- and polysaccharides (RROPs) were tested for their potential pharmacological properties using human skin fibroblasts in serial cultures. The substances tested were shown to stimulate cell proliferation, decrease elastase-type activity, stimulate collagen biosynthesis, and protect hyaluronan against free radical mediated degradation. These reactions appear to be triggered by the mediation of a specific alpha-L-rhamnose recognizing lectin-site acting as a receptor, transmitting signals to the cell-interior.

Effect of advanced glycation end-products on cell proliferation and cell death.

The effect of advanced glycation end products (AGE-s) was studied on the proliferation and cell death of human skin fibroblasts in culture. Several AGE-products were prepared from proteins, a peptide and amino acids, using Glucose or Fructose, with or without Fe2+. The AGE preparations increased cell death at the 7th day, after only 72 hours of incubation.

Pharmacological properties of fucose. Applications in age-related modifications of connective tissues.

Fucose is the only component of glycoconjugates of vertebrates in the L-configuration. It exhibits a number of unique and interesting biological properties reviewed briefly in this article. Its constant end-standing position on glycan chains predisposes fucose to play a key role in cell-cell and cell-matrix interactions, mediated by several receptors such as those recognising the Lewis-type blood group substances, fucose-recognising lectines and the mannose-fucose receptors.

Studies on skin aging. Preparation and properties of fucose-rich oligo- and polysaccharides. Effect on fibroblast proliferation and survival.

Skin aging represents an important chapter of connective tissue aging and concerns an organ of vital importance. Here we describe the preparation as well as the biological properties of fucose-rich oligo- and polysaccharides (FROPs), composed of polymers of a trisaccharide containing galactose, acetyl galacturonic acid and fucose, from the original high molecular weight bacterial polysaccharide (Fucogel), Solabia, France). Using endoglycosidases, oligo- and polysaccharides were prepared and characterized by physical and chemical procedures.

Protection by L-fucose and fucose-rich polysaccharides against ROS-produced cell death in presence of ascorbate.

It was shown previously, that millimolar concentrations of ascorbate have cytotoxic and anti-proliferative effects (Eur. J. Clin.

Regulation of elastase-type endopeptidase activity, MMP-2 and MMP-9 expression and activation in human dermal fibroblasts by fucose and a fucose-rich polysaccharide.

Tissue loss during ageing and age-dependent pathologies are the result of a disturbed regulation of proteolytic activities. Elastase-type endopeptidases, especially MMP-2 and -9, play an important role in this respect. Dermal fibroblast cultures and skin explant cultures were used in order to measure the efficiency of fucose and fucose-rich polysaccharides to downregulate the elastase-type endopeptidase activity.

Inhibition of cell proliferation and fibronectin biosynthesis by Na ascorbate.

Background: The importance of ascorbate on the production of extracellular matrix proteins (as elastin and collagens) is now well documented, but no studies have been published concerning its effects on fibronectin biosynthesis. Fibronectin is important for cell attachment and for proliferation.

Materials And Methods: The effects of Na ascorbate were investigated on cell attachment, proliferation, viability and fibronectin biosynthesis by human skin fibroblasts in vitro.

Cell death by overload of the elastin-laminin receptor on human activated lymphocytes: protection by lactose and melibiose.

Background: Activated human lymphocytes were shown to express the elastin-laminin receptor in vitro and also in vivo in atherosclerotic plaques. In the presence of the agonist, elastin peptides, this receptor was shown to mediate an increased cell proliferation and an increased synthesis and excretion of an elastase-type serine endopeptidase. In this study, we investigated the variation of the above reaction as a function of agonist concentration.

Cell death induced in lymphocytes expressing the elastin-laminin receptor by excess agonists: necrosis and apoptosis.

This manuscript summarizes our experiments carried out during the last years on the expression of the elastin-laminin receptor on human activated lymphocytes and cell death triggered by the activation of this receptor by its agonists, elastin peptides. We could distinguish two types of cell reactions, depending on the elastin peptide concentration added to the cell culture media of lymphocytes. At low concentrations (1-10 micrograms/mL, 1.

Aging and matrix biology.

This introduction to a theme issue of Pathologie Biologie on the extracellular matrix starts with a brief overview of the advances made over the last few years and of the increasing specialization they have resulted in. A review is then presented of cell-matrix interactions, with emphasis on those mediated by the elastin-laminin receptor during physiologic processes and during aging and age-related diseases. The activated human lymphocyte expressing the elastin-laminin receptor is used as an example.

Lymphocytes in human atherosclerotic plaque exhibit the elastin-laminin receptor: potential role in atherogenesis.

The purpose of this immuno-histochemical study was to investigate if lymphocytes, present in the human atherosclerotic plaque, exhibit the elastin-laminin receptor. We showed recently that human activated lymphocytes in vitro express this receptor. Briefly, we demonstrated by immuno-localization experiments and by flow cytometry that this receptor is available on the cell surface of human activated lymphocytes, free to react with ligands and show capping.

Human helper and memory lymphocytes exhibit an inducible elastin-laminin receptor.

We showed recently that human activated lymphocytes express the elastin-laminin receptor. In this study, we were interested in the kinetics of the induction of this receptor on human activated lymphocytes in vitro and in the quantification of its expression on different human lymphocyte subsets. It appears that the expression of the elastin-laminin receptor is a general property of most activated human lymphocytes but strongly dependent on the lymphocyte subsets.

Presence of the elastin-laminin receptor on human activated lymphocytes.

A variety of cells - fibroblasts, vascular smooth muscle cells, endothelial cells, monocytes and polymorphonuclear leukocytes (PMNs) - carry the elastin-laminin receptor. The activation of this receptor by elastin peptides triggers a variety of reactions as chemotactic movements to an elastin peptide gradient, release of lytic enzymes and oxygen-free radicals, modifications of ion fluxes. We now show that human lymphocytes also express this receptor.

Alterations in nucleoside monophosphate concentrations in 3LL tumours after combined treatment with tiazofurin and 5-hexyl-2'-deoxyuridine.

The IMP and GMP concentrations were compared after treatment with tiazofurin alone and in combination with 5-hexyl-2'-deoxyuridine (HUdR) in 3LL-HH adenocarcinoma in vivo. The elevation in IMP/GMP ratio, indicating guanylate depletion and increase of inosine-5'-monophosphate concentration, showed a dose dependence and was the highest at the 7th hour after treatment with tiazofurin. HUdR application alone caused only a modest change in the nucleotide concentration of LL-HH tumour.