Down-regulation of lysyl oxydase-like in aging and venous insufficiency

Background: Elastin expression is higher in tissues where elastic fibres are essential for the correct maintenance of function such as blood vessels. Elastin expression usually diminishes with age, however, it may be re-expressed in response to injury or repair processes. Some authors attribute the characteristic loss of elasticity of the varicose vein to a drop in the population of smooth muscle cells in the media layer. A reduction in elastin has been observed in chronic venous insufficiency, but little is known about some of the factors involved in elastin synthesis such as lysyl oxidases. The aim of this study was to examine the in vivo expression of the elastin precursor, tropoelastin (TE), and lysyl oxidase-like 1 (LOXL1), a cross-linking enzyme responsible for elastin polymer deposition. The effects of age on these expression patterns were also evaluated. Methods: Saphenous vein segments were obtained during surgery from organ donors (controls, n=20) and subjects with venous insufficiency (varicose veins, n=20). Both these groups were subdivided according to subject age into <50 years (n=10) and ³ 50 years (n=10). Control and varicose vein tissue specimens were immunolabelled using anti-tropoelastin and antiLOXL1 antibodies and also subjected to Western blot analysis. Results: Our results indicate that the levels of these markers of elastin synthesis (LOXL/tropoelastin) in the vein wall diminish in a significant way (p<0.05) with the age factor. Excluding the age factor, LOXL1 was significantly decreased in the varicose condition (p<0.05). In the younger pathological population they showed an inverse relationship (LOXL decreased, tropoelastin increased). Conclusions: The already established reduction in elastin in the varicose condition may be related, at least in part, to the decreased LOXL1 levels observed here. These events could reduce spontaneous reticulation of elastin and the partial loss of tissue elasticity in this group of patients

Biological properties of synthetic elastin peptides

Biological properties of synthetic elastin peptide

Latent-transforming growth factor beta-binding protein-2 (LTBP-2) is required for longevity but not for development of zonular fibers

Latent-transforming growth factor beta-binding protein 2 (LTBP-2) is a major component of arterial and lung tissue and of the ciliary zonule, the system of extracellular fibers that centers and suspends the lens in the eye. LTBP-2 has been implicated previously in the development of extracellular microfibrils, although its exact role remains unclear. Here, we analyzed the three-dimensional structure of the ciliary zonule in wild type mice and used a knockout model to test the contribution of LTBP-2 to zonule structure and mechanical properties. In wild types, zonular fibers had diameters of 0.5–1.0 micrometers, with an outer layer of fibrillin-1-rich microfibrils and a core of fibrillin-2-rich microfibrils. LTBP-2 was present in both layers. The absence of LTBP-2 did not affect the number of fibers, their diameters, nor their coaxial organization. However, by two months of age, LTBP-2-depleted fibers began to rupture, and by six months, a fully penetrant ectopia lentis phenotype was present, as confirmed by in vivo imaging. To determine whether the seemingly normal fibers of young mice were compromised mechanically, we compared zonule stress/strain relationships of wild type and LTBP-2-deficient mice and developed a quasi-linear viscoelastic engineering model to analyze the resulting data. In the absence of LTBP-2, the ultimate tensile strength of the zonule was reduced by about 50%, and the viscoelastic behavior of the fibers was altered significantly. We developed a harmonic oscillator model to calculate the forces generated during saccadic eye movement. Model simulations suggested that mutant fibers are prone to failure during rapid rotation of the eyeball. Together, these data indicate that LTBP-2 is necessary for the strength and longevity of zonular fibers, but not necessarily for their formation.Y. Shi, W. Jones, W. Beatty, Q. Tan, R.P. Mecham, H. Kumra, D.P. Reinhardt, M.A. Gibson, M.A. Reilly, J. Rodriguez and S. Bassnet

Optimization of elastolysis conditions and elastolytic kinetic analysis with elastase from Bacillus licheniformis ZJUEL31410

The solubilization of elastin by Bacillus licheniformis elastase cannot be analyzed by conventional kinetic methods because the biologically relevant substrate is insoluble and the concentration of enzyme-substrate complex has no physical meaning. In this paper we report the optimization of elastolysis conditions and analysis of elastolytic kinetics. Our results indicated that the hydrolyzing temperature and time are very important factors affecting elastolysis rate. The optimized conditions using central composite design were as follows: elastolysis temperature 50 °C, elastase concentration 1×10(4) U/ml, elastin 80 mg, elastolytic time 4 h. Investigation of the effects of substrate content, elastase concentration and pH was also revealed that low or high elastin content inhibits the elastolysis process. Increasing elastase improves elastin degradation, but high elastase may change the kinetics characterization. Alkaline environment can decrease elastin degradation rate and pH may affect elastolysis by changing elastase reaction pH. To further elucidate the elastolysis process, the logistic model was used to elastolysis kinetics study showing clearly that the logistic model can reasonably explain the elastolysis process, especially under lower elastase concentration. However, there is still need for more investigations with the aid of other methods, such as biochemical and molecular methods