desmosine and Arteriosclerosis

The elastic fibers present in various connective tissues of the body are responsible for physiologic elasticity of the organs. These fibers consist of 2 distinct components, elastin and the elastic fiber microfibrils. Controlled synthesis and balanced interaction of these 2 components are essential for normal fibrillogenesis. The intracellular biosynthesis of elastin by connective tissue cells, such as smooth muscle cells, involves assembly of the polypeptide chains on the membrane-bound ribosomes, hydroxylation of some prolyl residues to hydroxyproline, and secretion of the polypeptides packaged in Golgi vacuoles. In the extracellular space the elastin molecules assemble into fiber structures which are stabilized by the synthesis of complex covalent cross-links, desmosines. Recently, aberrations in the structure or metabolism of elastin have been detected in a variety of heritable and acquired diseases affecting skin and other connective tissues. These conditions include pseudoxanthoma elasticum, cutis laxa, and elastosis perforans serpiginosa, as well as arteriosclerosis and other degenerative changes of the vascular connective tissues.

Topics: Amino Acids; Arteriosclerosis; Chemical Phenomena; Chemistry; Collagen Diseases; Connective Tissue; Contractile Proteins; Cutis Laxa; Desmosine; Ehlers-Danlos Syndrome; Elastic Tissue; Elastin; Female; Glycoproteins; Humans; Hydroxyproline; Marfan Syndrome; Menkes Kinky Hair Syndrome; Muscle Proteins; Pancreatic Elastase; Peptide Biosynthesis; Protein Precursors; Pseudoxanthoma Elasticum; X Chromosome

Topics: Aging; Amino Acid Sequence; Amino Acids; Animals; Arteriosclerosis; Calcium; Cholesterol; Copper; Cyanogen Bromide; Desmosine; Diet; Elastin; Microbial Collagenase; Models, Chemical; Molecular Weight; Protein Conformation; Swine; Tyrosine

Elastin, an extracellular matrix protein, constitutes about 30% of the dry weight of the arteries. Elastolysis induced by inflammatory processes is active in chronic arterial diseases. However, elastogenesis in arterial diseases has received little attention. In this work we hypothesized that disordered elastogenesis is active in matrix remodeling in atheroma and abdominal aortic aneurysm (AAA).. Human AAA and atheroma have 4- to 6-fold more tropoelastin protein than nondiseased arteries. The smooth muscle cell-containing media and fibrous cap of atherosclerotic arteries contain ordered mature elastin, whereas macrophage (MPhi)-rich regions often have disorganized elastic fibers. Surprisingly, in addition to smooth muscle cells, MPhis in diseased arteries also produce the elastin precursor tropoelastin, as shown by double immunostaining, in situ hybridization, and reverse transcription-polymerase chain reaction for tropoelastin mRNA. Cultured monocyte-derived MPhis can express the elastin gene. AAA have 9-fold but atheroma only 1.6-fold lower levels of desmosine, a marker for mature cross-linked elastin, than normal arteries.. This study demonstrates ongoing but often ineffective elastogenesis in arterial disease and establishes human macrophages as a novel source for this important matrix protein. These results have considerable import for understanding mechanisms of extracellular matrix remodeling in arterial diseases.

Topics: Aorta; Aortic Aneurysm, Abdominal; Arteriosclerosis; Cells, Cultured; Desmosine; Elastin; Extracellular Matrix Proteins; Humans; In Situ Hybridization; Macrophages; RNA, Messenger; Tropoelastin

We tried to develop an experimental model using mice for the primary screening of antiatherosclerotic agents. Male ICR strain mice were given a high-cholesterol diet supplemented with 10% linoleic acid for 14 weeks. Throughout the experimental period, weight gain of these mice was significantly inhibited as compared to that of control mice given a basal diet, but displayed a steady increase comparable to that of the high-cholesterol diet without linoleic acid. The cholesterol and linoleic acid-fed mice showed increased serum cholesterol and phospholipid levels, and decreased serum triglyceride and high-density lipoprotein-(HDL) cholesterol levels and lecithin/cholesterol acyltransferase (LCAT) activity, as well as a markedly increased lipid peroxide level which was a characteristic appearance in the serum of this mouse model. At the end of the experiment, uniform and significant increases in cholesterol, notably cholesteryl ester, were observed in the aorta. Also found were marked decreases in the aorta contents of desmosine and isodesmosine, which are cross-linking amino acids present only in the elastin. Histological observations showed accumulations of fatty droplets in the intima. These changes were much less in mice receiving a high-cholesterol diet without linoleic acid. In this mouse model, probucol prevented elevation of serum cholesterol, phospholipid, and cholesterol accumulation in the aorta. Increases in lipid peroxide level and decreases in LCAT activity were also prevented. These findings indicate that this mouse model is useful for primary screening of antiatherosclerotic agents with antioxidative activity.

Topics: Animals; Anticholesteremic Agents; Aorta; Arteriosclerosis; Cholesterol; Cholesterol, Dietary; Desmosine; Disease Models, Animal; Drug Evaluation, Preclinical; Hypercholesterolemia; Linoleic Acid; Linoleic Acids; Lipid Peroxides; Lipids; Male; Mice; Mice, Inbred ICR; Phosphatidylcholine-Sterol O-Acyltransferase; Probucol

A rapid, sensitive high-performance liquid chromatographic method has been developed for the determination of desmosine (DES) and isodesmosine (IDE), the specific cross-linking amino acids of elastin, in the tissue hydrolysates of rats. DES and IDE in the hydrolysate samples were separated on a C18 column using 0.1 M phosphate buffer-acetonitrile (2.8:1) containing 20 mM sodium dodecyl sulphate (final pH 4.5) followed by detection at 270 nm. The recoveries of the added standards of DES and IDE from the aorta hydrolysate samples were 99.6 +/- 2.7% and 98.4 +/- 1.8%, respectively (n = 10). At DES and IDE concentrations of 2 micrograms/ml, within- and between-run precisions were 1.11-1.85% and 0.55-1.24%, respectively. The detection limits of DES and IDE were 0.1 microgram/ml with a 50-microliter injection at a signal-to-noise ratio of 3. The method was successfully applied to a study of the alteration of DES and IDE contents (i.e. elstin contents) in the tissues of rats treated with beta-aminopropionitrile and an atherogenic diet. A negative correlation between the contents of these amino acids and of cholesterol was noted in the atherosclerotic aorta.

Topics: Amino Acids; Animals; Arteriosclerosis; Chromatography, High Pressure Liquid; Desmosine; Diet, Atherogenic; Elastin; Hydrogen-Ion Concentration; Isodesmosine; Liver; Lung; Male; Muscle, Smooth, Vascular; Rats; Rats, Inbred Strains

The cross-links histidinoalanine (HA); pyridinoline (Pyr); desmosine (Des); and isodesmosine (Ides) in human atherosclerotic aortas were studied. Only HA showed a significant increase in calcified aortas, with a high concentration in the insoluble "mineralized" fraction, which was separated out after treatment of tissues with pronase E. The cross-links composition was similar among "mineralized" fractions prepared from tissues of varying degrees of calcification: values were 2.40; 0.10; 0.17; and 0.16 moles per 1000 moles of amino acid residues for HA; Pyr; Des; and Ides, respectively. The findings suggest that the HA-containing peptide may play an important role in the calcification process of aortic tissues.

Topics: Amino Acids; Aorta; Arteriosclerosis; Calcinosis; Cross-Linking Reagents; Desmosine; Dipeptides; Humans; Isodesmosine

Topics: Adolescent; Adult; Aged; Aging; Aorta; Arteriosclerosis; Breast; Breast Neoplasms; Child; Desmosine; Elastin; Female; Humans; Middle Aged; Pancreatic Elastase