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Introduction and Review of Biological Background
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Elastins are very large, highly cross-linked proteins similar to collagens. Elastins form a three-dimensional mesh network in various tissues to give elastic, resilient properties to tissues. The mesh network can be stretched into almost parallel fibers, which return to their original shape. Elastins are rich in ligaments, skin, large blood vessels, and lungs, which are all tissues with the need for expansion and reversion to original shape. Because of the highly cross-linked structure of elastin meshes, turnover is very slow (months to years), and elastins are very resistant to degradation. Unlike collagens, elastins form desmosine, an amino acid unique to elastin, that forms covalent bonds for cross-links to adjacent elastin polypeptide chains. Some of the synthetic machinery used for collagen synthesis is also duplicated for elastin (such as prolyl hydroxylase), but there is no hydroxylation of lysine in elastin. For nutritional purposes, elastin synthesis relies on many of the same nutrient needs as collagen, but without the specific needs for copper or calcium (see Table 3).
Proteins for Conditioning Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Elastin is the second most common connective tissue protein after collagen, constituting 60-80% of the dry weight of blood vessels and ligaments. Its unique amino acids are desmosine and isodesmosine. In skin, elastin fibers enmeshed in collagen provide skin with its elastic strength (23). Excessive sun exposure leads to abnormal, disoriented elastin fibers and folding of the epidermis (i.e., wrinkles) (26). Like hydrolyzed collagen, hydrolyzed elastin of 2000 to 5000 Da is a good film former, but is much less hygroscopic due to its much lower polar and charged amino acid content (see Tables 2 and 3). As a result it has much higher hydroalcoholic and polyol solubility and can reduce swelling of hair during permanent waving and coloring processes. Like other low-polarity protein hydrolyzates, such as silk (17), it may be preferable to collagen (and other more hydrophilic hydrolyzates) where humidity resistance is desirable.
The Noncollagenous Proteins of the Intervertebral Disc *
Published in Peter Ghosh, The Biology of the Intervertebral Disc, 2019
Elastin is a highly insoluble protein rich in hydrophobic amino acids and contains few polar functional groups. It is synthesized as a soluble precursor molecule, tropoelastin (mol wt 72,000), of similar amino acid composition to insoluble elastin, but contains additional lysine residues which are subsequently involved in cross-link formation. These convert the tyopoelastin to insoluble elastin. Cross-linking is achieved via aldehyde (allysine) formation derived from lysine residues by the enzyme lysyloxidase. The cross-links of elastin contain the unique amino acids desmosine and isodesmosine.78,79 Other cross-links have recently been described,80–83 some of which are identical to those present in collagen.84 However, all of the known cross links of elastin are derived from lysine, whereas hydroxylysine is also utilized in collagen cross-link formation. In mature elastin, dihydrodesmosine and dihydroisodesmosine are more prevalent than the desmosine and isodesmosine ring structures. Problems, however, are encountered in the unequivocal demonstration of cross-linking structures in mature elastin, since the harsh extractive conditions required for its solubilization partially destroy desmosine/isodesmosine and intermediate cross-link structures.85,86
Gene therapy for alpha-1 antitrypsin deficiency: an update
Published in Expert Opinion on Biological Therapy, 2023
Debora Pires Ferreira, Alisha M Gruntman, Terence R Flotte
The progression of destruction of the lung tissue is currently being evaluated using both imaging and biochemical biomarkers. The measurement of computed tomography (CT) lung density has been particularly informative in studies of augmentation therapy, including the RAPID trial and the RAPID extension [76, 77]. In those studies, the rate of loss of lung density was reduced by nearly half among the group receiving an early start on augmentation therapy. The preservation of CT lung density corresponds with a preservation of pulmonary function by spirometry as well, but with less variability in the measurement. In a similar fashion, biochemical biomarkers of ECM loss have proven to be valuable outcome measures in evaluating the effects of therapies in this patient population. In particular, the measurement of desmosine and isodesmosine have correlated well with improvements in a wide range of pro-inflammatory cytokines, serum markers of protease/antiprotease imbalance and other indices of AAT biological activity [78].
Personalizing liver targeted treatments and transplantation for patients with alpha-1 antitrypsin deficiency
Published in Expert Review of Precision Medicine and Drug Development, 2021
Anita Pye, Sheeba Khan, Tony Whitehouse, Alice M Turner
One difference in liver disease is that the major outcome measure currently being used in phase II trials is invasive – liver biopsy – unlike the lung function measures used in emphysema. Invasive measures for efficacy of augmentation therapy (eg. measurement of AAT level in bronchoalveolar lavage) have typically only been used in phase I trials. However the principle of showing that a quantitative imaging measure relates to an accepted measure of disease still holds, as does the idea that a blood biomarker could add value. Elastography, or MRI-elastography may have promise in the imaging arena for the liver, indeed current phase II work (NCT03945292) uses adaptive design to try and reduce the need for biopsy if imaging is sufficiently reflective of biopsy. In emphysema desmosine, a marker of elastin breakdown, has been shown to change with augmentation therapy [74], and a number of phase II studies are now looking at this as an outcome; whether it will be suitable for use in phase III is not yet known, but the potential for combination with an imaging measure to further aid patient stratification or selection is interesting.
Association between serum elastin-derived peptides and abdominal aortic calcification in peritoneal dialysis patients: a cross-sectional study
Published in Renal Failure, 2021
Shizhu Zhao, Jingyuan Cao, Jianzhong Li, Xiaochun Yang, Peiyang Cao, Jingjing Lan, Guoyuan Lu
Elastin degradation participates in the pathogenesis of atherosclerosis and medial calcification [25,26], both of which coexist in CKD. EDPs in CKD patients were significantly higher than in controls and were associated with increased aortic stiffness and all-cause mortality [27]. Desmosine was also found to correlate with coronary artery calcification rather than emphysema in patients with COPD [28], indicating EDPs was more relevant to elastin of the vascular rather than the lungs. Apart from that, circulating EDPs were also considerably elevated in diabetes with microvascular complications such as albuminuria and retinopathy [29]. Similar to those researches of strong correlation between EDPs and vascular disease, we found serum EDPs was significantly higher in PD patients with AAC, and it increased as the calcificaiton worsened. Further, elevated EDPs was a vital factor related to the risk of AAC and severe AAC in PD patients, prompting its important role in AAC risk stratification.