DOCSLIB.ORG

The Science of Aging Skin Leslie Baumann, MD; Susan Weinkle, MD

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Science of Aging Skin Leslie Baumann, MD; Susan Weinkle, MD REVIEW Improving Elasticity: The Science of Aging Skin Leslie Baumann, MD; Susan Weinkle, MD Although collagen changes from both chronologic aging and photoaging have been well stud- ied, there is a dearth of research into the elastin component of the dermis. No products have been approved by the US Food and Drug Administration for either replacing elastin or stimulating its syn- thesis. Recently, a zinc complex was shown to increase dermal elastin staining, hypodermal fat, and epidermal thickness in animal studies. Histologic studies of the same zinc complex in humans have revealed increased deposition of functional elastin fibers following 10 days of use. In the clinical trials reported here, there was an increase in functional elastin, as well as improvements in fine lines and wrinkles. COSNo adverse events were noted. DERM ollagen and elastin are the fibers that make collagen bundles and endow the skin with rebounding up the dermal matrix. Cosmetic dermatol- properties. Tropoelastin molecules, which are precur- ogists have long used topical medications, sors to elastin, bind covalently with cross-links to form fillers, and light-based and laser-based elastin. Elastin fibers are assembled on bundles of micro- therapies to improve the loss of collagen fibrils composed of fibrillin. The latter forms a template Cthat occurs in aging skin. However, until recently, no fill- on which elastin is deposited.1 Most elastin production ers orDo topical agents have been availableNot to treat the loss is restricted Copy to a narrow window of development. Elas- of function of elastin, which is also an important feature togenesis increases dramatically during fetal life, peaks of dermal photoaging. The loss of collagen, elastin, and near birth and early neonatal life, decreases significantly other dermal matrix components translates into the wrin- thereafter, and is nearly nonexistent by maturity. kled, sagging, fragile skin associated with chronologic In contrast to collagen fibers, elastin fibers are present aging and photoaging. in various stages of maturity. Oxytalan fibers, the least mature elastin fibers, course perpendicularly from the THE ROLE OF ELASTIN IN THE dermal-epidermal junction to the top of the reticular APPEARANCE OF AGING SKIN dermis whereas elaunin fibers, the more mature elastin Elastin is a resilient connective tissue in the extracel- fibers, attach to a horizontal plexus of fibers found in lular matrix. Elastin fibers are found at the periphery of the reticular dermis. Elaunin fibers are more mature because they have more elastin deposited on the fibril- Dr. Baumann is Chief, Division of Cosmetic Dermatology, lin mesh. The most mature elastin fibers are unnamed and Associate Professor, Department of Dermatology and and are found deeper in the reticular dermis.1,2 This Cutaneous Surgery, Univesity of Miami School of Medicine, fibrous network running from the uppermost section of Florida. Dr. Weinkle is Assistant Clinical Professor of the papillary dermis to just beneath the basement mem- Dermatology, University of South Florida, Tampa, and in private brane lends elasticity to young skin. As this network practice, Bradenton, Florida. deteriorates with age, the loss of or damage to elastin Dr. Baumann is an advisory board member and investi- fibers may play a significant role in skin sagging and loss gator for Allergan, Inc; Dermik Laboratories; and Medicis of youthful resilience.3,4 Pharmaceutical Corporation; and an advisory board member Photoaging initially leads to hyperplasia of elastin fibers and consultant for Revance Therapeutics, Inc. according to the level of UV exposure. Later, a degenerative 168 Cosmetic Dermatology® • MARCH 2007 • VOL. 20 NO. 3 Copyright Cosmetic Dermatology 2010. No part of this publication may be reproduced, stored, or transmitted without the prior written permission of the Publisher. IMPROVING ELASTICITY IN AGING SKIN response occurs with resultant loss of skin elasticity.5,6 When viewed by light microscopy, degraded elastin appears as an amorphous substance that accumulates in UV Reactive Oxygen Species the papillary dermis.1,7 The resultant elastosis, a hallmark of photoaged skin, is due to the breakdown of elastic fibers and loss of functional elastin. Defective or dam- aged elastin may lead to wrinkles, even in the absence of Map Kinases sun exposure and aging. A child with wrinkled skin syn- drome was shown to have a deficiency of elastin fibers, ERK JNK which demonstrates the important contribution of elastin to skin integrity.1 Studies have demonstrated that, with aging, there is a c-Jun c-Fos reduction in the elastin content of protected areas of the skin. In a study of Egyptian subjects, the relative amount of elastin in the non–UV-exposed abdominal skin decreased significantly from 49.2%±0.6% in the first decade of life to Activator Protein 1 30.4%±0.8% in the ninth decade.2 Another study on elas- tin content in the non–UV-exposed skin of the buttocks of Complicated signaling cascade that leads to collagen degradation. 91 white subjects between 20 and 80 years of age showed ERK indicates extracellular signal–related kinase; JNK, c-Jun amino- a 51% reduction in elastin tissue.8 terminal kinase. MECHANISMS OF DERMAL AGING Although chronologic aging and photoaging have often formation of advanced glycation end products, which form been considered to be separate processes, research indi- covalent cross-links between proteins that can alter their cates a potential overlap at the molecular and clinical structure and function. Advanced glycation end products 9,11 COS DERM levels. There is substantial evidence that skin aging have been shown to accumulate in tissues with a low is mediated by direct absorption of UV radiation by turnover rate, including dermal collagen and elastin. At chromophores in the skin leading to the production of approximately 35 years of age, glycation of the dermis has reactive oxygen species (ROS).10 ROS-mediated photo- been shown to begin; it then increases rapidly with age.13 chemical reactions can oxidize cutaneous proteins, lipids, Although changes in dermal collagen are well studied, and DNA. The Figure shows the complicated signaling research on changes in dermal elastin is less extensive. cascadeDo that leads to collagen degradation.Not UV radiation In a studyCopy designed to demonstrate differences between leads to the generation of ROS and the formation of the chronologically aged and photoaged elastic tissue, Bouissou mitogen-activated protein kinases (MAPKs), extracellular et al14 found that low–sun-exposed skin showed a disap- signal–related kinase, and c-Jun amino-terminal kinase. pearance of oxytalan fibers beginning at 30 years of age. This, in turn, leads to upregulation of the transcrip- By 40 years of age, there were no oxytalan fibers, and there tion factor c-Jun. When sufficient c-Jun is expressed to was significant lysis of elastic fibers. In high–sun-exposed heterodimerize with c-Fos, activator protein 1 (AP-1) is skin, the same age-related lesions were noted, but elastotic produced.9,10 AP-1 is a transcription factor that stimulates degeneration in the reticular and deep dermis was also the matrix metalloproteinases (MMPs) and reduces type I seen. Chronologic aging appeared to be characterized by procollagen, both of which are seen in chronologically the disintegration of elastic fibers, whereas photoaging was aged and photoaged skin.9,10 Findings reported by Varani characterized by thicker, elastotic fibers. The authors sug- et al11 have suggested that both chronologically aged gested that the lesions of chronologic aging may be due to and photoaged skin also exhibit similar features, such proteases originating in fibroblasts and that the lesions of as connective tissue alterations (eg, progressive loss of photoaging may be due to UV stimulation of fibroblasts. dermal fibroblasts, increased space between connective Scharffetter-Kochanek et al15 have suggested that the AP-1 tissue fiber bundles, and increased disorganization of and MMP cascade may be operative in the characteris- fiber bundles). In addition to the activation of AP-1 and tic elastin changes because MMP-2 has been shown to the MMP cascade, matrix degradation is also mediated degrade both elastin and collagen. by inhibition of transforming growth factor b signaling.12 Human leukocyte elastase (HLE) may play a role in Recently, there has been interest in the contribution elastin degradation. It has been shown that lysosyme of glycation to skin aging. Protein damage by reducing binding to elastin fibers, which may be induced by UV sugars and other reactive carbonyl species leads to the exposure, may prevent their degradation by HLE. A study VOL. 20 NO. 3 • MARCH 2007 • Cosmetic Dermatology® 169 Copyright Cosmetic Dermatology 2010. No part of this publication may be reproduced, stored, or transmitted without the prior written permission of the Publisher. IMPROVING ELASTICITY IN AGING SKIN by Seite et al8 revealed that the elastolytic activity of HLE the cosignaling pathways involved, moderate epidermal was reduced by up to 38% after lysosyme binding to areas thickening and marked reversal of hypodermal fat atro- of damaged elastin. phy will also occur over concentration ranges effective for elastin production. COSMETIC MANAGEMENT OF THE AGING DERMIS: FOCUS ON ELASTIN CLINICAL STUDY 1 Cosmetic dermatologists have long addressed colla- Patients and Methods gen loss via collagen replacement injections or topical In a prospective, randomized, double-blind, vehicle- products that support the formation of new collagen. controlled clinical study, both eyes of each of 26 subjects However, no products or procedures have been available received once-daily applications of either a zinc complex to address the changes in elastin resulting in the char- cream for the eye area or a copper peptide formulation. acteristic loss of resilience seen in chronologically aged Subjects were healthy adult females aged 37 to 60 years and photoaged skin.16 Although many topical products who were regular users of eye creams. Clinical follow-up contain collagen and elastin and claim to increase the was at 1, 2, and 4 weeks.
Load more

Recommended publications
  • Flavio Akira Sakae Distribuição Das Fibras Colágenas E Do Sistema De
    Flavio Akira Sakae Distribuição das fibras colágenas e do sistema de fibras elásticas na camada superficial da lâmina própria da prega vocal com edema de Reinke Tese apresentada à Faculdade de Medicina da Universidade de São Paulo para obtenção do título de Doutor em Ciências Área de concentração: Otorrinolaringologia Orientador: Prof. Dr. Domingos Hiroshi Tsuji São Paulo 2008 Dados Internacionais de Catalogação na Publicação (CIP) Preparada pela Biblioteca da Faculdade de Medicina da Universidade de São Paulo Óreprodução autorizada pelo autor Sakae, Flavio Akira Distribuição das fibras colágenas e do sistema de fibras elásticas na camada superficial da lâmina própria da prega vocal com edema de Reinke / Flavio Akira Sakae. -- São Paulo, 2008. Tese(doutorado)--Faculdade de Medicina da Universidade de São Paulo. Departamento de Oftalmologia e Otorrinolaringologia. Área de concentração: Otorrinolaringologia. Orientador: Domingos Hiroshi Tsuji. Descritores: 1.Edema laríngeo 2.Colágeno 3.Tecido elástico 4.Membrana mucosa 5.Cordas vocais USP/FM/SBD-146/08 "O único homem que está isento de erros, é aquele que não arrisca acertar." Albert Einstein Dedicatória Aos meus queridos pais, Masao e Junko, por tudo que fazem por mim, pelo apoio incondicional e amor eterno. São os meus ídolos. A minha esposa, Renata, amor da minha vida, pela alegria de viver, companheirismo e incentivo constante. A minha irmã, Cristiane, por ter contribuído em todos os passos de minha vida. Agradecimentos Ao meu orientador, Prof. Dr. Domingos Hiroshi Tsuji pela oportunidade e apoio na concretização deste sonho. Sua amizade e franqueza foram essenciais na elaboração deste trabalho. É o grande mestre. Ao Prof. Dr.
    [Show full text]
  • Differentiation of the Secondary Elastic Cartilage in the External Ear of the Rat
    Int..I. Dc\'. Bi,,!. 35: 311-320 (1991) 311 Differentiation of the secondary elastic cartilage in the external ear of the rat ZELIMIR BRADAMANTE*', LJILJANA KOSTOVIC-KNEZEVIC', BOZICA LEVAK-SVAJGER' and ANTON SVAJGER' 'Institute of Histology and Embryology and 2/nstitute of Biology, Faculty of Medicine, University of Zagreb, Republic of Croatia, Yugoslavia ABSTRACT The cartilage in the external ear of the rat belongs to the group of secondary cartilages and it has a unique structural organization. The chondrocytes aretransformed intotypical adipose cells, the proteoglycan cartilage matrix is reduced to thin capsules around the cells and the rest of the extracelullar matrix is occupied by a network of coarse elastic fibers. It appears late in development 116-day fetus) and needs more than one month for final development. The differentiation proceeds in several steps which partly overlap: the appearance of collagen fibrils, elastin fibers, the proteoglycan matrix, and the adipose transformation of chondrocytes. The phenotype of this cartilage and the course of its differentiation are very stable, even in very atypical experimental environmental conditions. The only exceptions are explants in organ culture in vitro and perichondrial regenerates. In these conditions the development of elastic fibers is slow and poor while the production of the proteogycan matrix is abundant. The resulting cartilage then displays structural characteristics of hyaline cartilage rather than those of the initial elastic one. KEY WORDS: elastic mrlilagf, tI/(Wdrogfllt'.\'i.\. plasfogellf'.\is, extenuil Ntr, rat Introduction Structural organization The elastic cartilage belongs to the group of secondary or ac- According to Baecker (1928) and Schaffer (1930) the cartilage cessory cartilages since it is not a part of the cartilagineous in the external ear (external auditory meatus and pinna) of the rat primordium of the body skeleton as is most hyaline cartilage can be defined as: a) cellular or parenchymatous, [jecause of the (Schaffer, 1930).
    [Show full text]
  • Clinical Outcomes of Elastin Fibre Defects
    ytology & f C H i o s l t a o n l o r g u y o Hassan et al., J Cytol Histol 2013, 4:1 J Journal of Cytology & Histology DOI: 10.4172/2157-7099.1000166 ISSN: 2157-7099 CommentaryResearch Article OpenOpen Access Access Clinical Outcomes of Elastin Fibre Defects Ashfaq Ul Hassan1*, Ghulam Hassan2, Zahida Rasool3 and Shabinul Hassan3 1Anatomy Department, SKIMS Medical College, Bemina, Srinagar, Kashmir, India 2Department of Anatomy, Al Qassim University, Saudi Arabia 3Islamic University of Science and Technology, Kashmir, India Abstract Elastic fibres are a major class of extracellular matrix fibres that are abundant in dynamic connective tissues such as arteries, lungs, skin and ligaments. Their structural role is to endow tissues with elastic recoil and resilience. They also act as an important adhesion template for cells, and they regulate growth factor availability. Mutations in major structural components of elastic fibres, especially elastin, fibrillins and fibulin-5, cause severe, often life-threatening, heritable connective tissue diseases such as Marfan syndrome, Menkes Syndrome, Cutis laxa. Elastic-fibre function is also frequently compromised in damaged or aged elastic tissues. The ability to regenerate or engineer elastic fibres and tissues remains a significant challenge, requiring improved understanding of the molecular and cellular basis of elastic-fibre biology and pathology. The aim of the article is to present in brief the structural details of elastin fibres, the defects and pleiotrophic effects as a result of damage and various clinical conditions associated with defects in elastin fibres ranging from rare pediatric syndromes to common entities like hypertension.
    [Show full text]
  • The Distribution of Elastin in Developing and Adult Rat Organs Using Immunocytochemical Techniques
    J. Anat. (1989), 165, pp. 225-236 225 With 6 figures Printed in Great Britain The distribution of elastin in developing and adult rat organs using immunocytochemical techniques COLIN FARQUHARSON AND SIMON P. ROBINS Rowett Research Institute, Biochemistry Division, Bucksburn, Aberdeen, Scotland (Accepted 20 December 1988) INTRODUCTION Elastin is the major protein of elastic system fibres, the principal connective tissue components responsible for the elasticity of a number of compliant organs such as aorta and skin. The elastic system fibres include elastic fibres, elaunin fibres and oxytalan fibres (Cotta-Pereira, Rodrigo & Bittencourt-Sampio, 1976). The elastic fibre consists of two morphologically distinct components (Ross & Bornstein, 1969): large amounts of an amorphous elastin core surrounded by a few microfibrils which are glycoprotein in nature (Sear, Grant & Jackson, 1981). Elaunin fibres also contain both components but are composed predominantly of microfibrils with little amorphous elastin, whereas oxytalan fibres are, exclusively, bundles of microfibrils (Cotta-Pereira et al. 1976). Oxytalan and elaunin fibres appear to be precursors of the mature elastic fibre (Gawlik, 1965). By light microscopy, demonstration of elastin has relied on characteristic staining reactions, chiefly with orcein, aldehyde-fuchsin and resorcin-fuchsin based stains. These classical stains do not however provide unequivocal identification of elastin as their specificity is now in doubt (Puchtler, Meloan & Pollard, 1976; Fakan & Saskova, 1982), thus limiting the use of these tinctorial dyes. Recently, there have been a number of reports using immunocytochemical detection of elastin by light microscopy (McCullagh, Barnard, Davies & Partridge, 1980; Barnard et al. 1982a; Barnard, Davies & Young, 1982 b; Fukuda, Ferrans & Crystal, 1983; Akita, Barrach & Merker, 1986).
    [Show full text]
  • Connective Tissue and Mesenchymal Tissue
    Connective tissue & mesenchymal tissue Prepared by: Ms. BR Tsauses Anatomical Pathology 2A (ANP611S) April 2020 Learning objectives • Understand connective and mesenchymal tissues in order to describe and apply appropriate staining techniques in Histology. Pre-learning Quiz • Please take the pre-learning quiz before proceeding with the presentation. Introduction • Connective tissue (CT) is of the four tissue types • Derived fom latin word connectere meaning to bind. • Is to connect together and provide support Introduction cont… • During embryonic development: ectoderm + endoderm = mesoderm • This germ layer is known as mesenchymal • Mesos means middle • Enchyma means infusion Connective tissue CT are divided into: 1. Connective tissue proper (dense, areolar, regular,adipose regular and reticular 2. Cartilage (hyaline elastic, fibrocartilage) 3. Bone( spongy or cancellous and dense or cortical) 4. Blood 5. Blood-forming (hematopoietic) Connective tissue cell types • Fibroblast • Mast cells • Histocytes • Adipose cells • Reticulor cells • Osteoblast and osteocytes • Chondroblast and chondrocytes • Blood cells and blood forming cells Intercellular substance • Intercellular substance (ICS) is composed of both amorphous(sulfated and non sulfated mucopolysaccharides) and formed elements (collagen, reticular fibers and elastic fibers) • The nature of these substance varies according its function (hard or dense or soft.) • Classified into: formed or fibrous type : gel or amorphous type Formed or fibrous intercellular substances Collagenenic fibers • Most common ICS found in large quantities in most sites • Appear as individual fibers as in loose areolar tissues e. g tendon • Collagenic fibers do not branch • Collagen types: Type (i) up to (vi) Reticular fibers • Provide bulk of supporting network of more cellular organs e. g spleen, lymph nodes, liver.
    [Show full text]
  • Tumours of the Anterior Uvea. III. Oxytalan Fibres in the Differential Diagnosis of Leiomyoma and Malignant Melanoma of the Iris
    Br J Ophthalmol: first published as 10.1136/bjo.64.11.867 on 1 November 1980. Downloaded from British Journal of Ophthalmology, 1980, 64, 867-874 Tumours of the anterior uvea. III. Oxytalan fibres in the differential diagnosis of leiomyoma and malignant melanoma of the iris M. S. NOOR SUNBA, A. H. S. RAHI, A. GARNER, R. A. ALEXANDER, AND G. MORGAN From the Department of Pathology, Institute of Ophthalmology, Judd Street, London SUMMARY The diagnostic potential of oxytalan fibre demonstration in differentiating between leiomyomas and spindle-cell malignant melanomas of the iris was investigated. It was found that oxytalan fibres were abundant in leiomyomata, both between and around the tumour cells, whereas they were found in small numbers only and usually near the iris muscle in malignant melanomata. Their presence and distribution, therefore, appear to offer a satisfactory method of differentiating between these tumours. Since the human choroid and ciliary body normally contain oxytalan fibres, the above findings are not relevant to malignant melanoma of these structures. Naevi and regressing aggregates of iris melanoma cells away from the main tumour mass may similarly be surrounded by misleading amounts of these fibres. Smooth muscle tumours of the iris have their origin the Mallory phosphotungstic acid haematoxylin copyright. in the dilator and sphincter muscles. Occasionally, stain, the Masson trichrome stain, and the gold however, they are found at other sites such as the impregnation technique is the most important anterior surface of the iris, where smooth muscle is diagnostic criterion. Since myoglial fibrils, which not naturally present.' Leiomyomas of the iris are are composed of contractile proteins, have been less common than malignant melanomata, their demonstrated in tissues other than smooth incidence varying between 4% and 33% of primary muscle,7-10 it is clear that their presence cannot be iris tumours.2 5 regarded as a pathognomonic feature of leiomyoma.
    [Show full text]
  • The Role of Elastic Fibers in Pathogenesis of Conjunctivochalasis
    Int J Ophthalmol, Vol. 10, No. 9, Sep.18, 2017 www.ijo.cn Tel:8629-82245172 8629-82210956 Email:[email protected] ·Review· The role of elastic fibers in pathogenesis of conjunctivochalasis Jing-Yun Gan, Qing-Song Li, Zhen-Yong Zhang, Wei Zhang, Xing-Ru Zhang Department of Ophthalmology, Putuo Hospital, Shanghai and even the whole body. Under the normal physiological University of Traditional Chinese Medicine, Shanghai 200062, conditions, elastic fibers are important components of China extracellular matrix, and influence the tissue flexibility and Correspondence to: Xing-Ru Zhang. Department of elasticity. Ophthalmology, Putuo Hospital, Shanghai University of In 1998, Meller and Tseng[2] proposed the hypothesis which Traditional Chinese Medicine, Shanghai 200062, China. states that mechanism of CCh is via accumulation of degrading [email protected] enzymes which resulted in elastotic degeneration and Received: 2016-11-22 Accepted: 2017-03-23 collagenolysis of bulbar conjunctiva in the tears as a result of delayed tear clearance. Abstract Although, a lot of research has been done on it, the precise ● The PubMed, MEDLINE databases and China National etiology of CCh remains obscure. So we summarize the Knowledge Infrastructure (CNKI) were searched for previous literatures and analyze the current situation on the information regarding the etiology and pathogenesis hypothesis of elastic fibers. of conjunctivochalasis (CCh) and the synthesis and MATERIALS AND METHODS degradation of elastic fibers. After analysis of the literature, The following electronic databases were screened: PubMed, we found elastic fibers was a complex protein molecule China National Knowledge Infrastructure (CNKI). The from the structure and composition; the degradation of following search equation was used: “CCh (all fields)” OR elastic fibers was one of the histopathological features “elastic tissue (MeSH terms)”, “elastic tissue (MeSH terms)” of the disease; the vast majority of the factors related to AND “2011/1/1 (PDAT):2016/5/31 (PDAT)”.
    [Show full text]
  • Elastic Fibers in the Rat Exorbital Lacrimal Gland Duct System
    Investigative Ophthalmology & Visual Science, Vol. 30, No. 9, September 1989 Copyright © Association for Research in Vision and Ophthalmology Elastic Fibers in the Rat Exorbital Lacrimal Gland Duct System Mortimer Lorber In the rat, each paired subcutaneous exorbital lacrimal gland overlies the retromandibular area. The fibrous cord containing its ducts passes over the masticatory muscles to the temporal canthus. Thus, the lacrimal system must accomodate both jaw and lid movements. To see whether elastic fibers exist to modulate alterations in tension caused by such movements, light and electron micrographs were made of its duct system. The innermost elastic fibers are connected by elaunin fibrils and oxytalan microfibrils to the lamina densa, particularly near the hemidesmosomes. The innermost elastic fibers appear to be longitudinal and about 0.2 nm from the lamina densa. Circumferential fibers exist about 0.8-3.2 nm from that structure. More peripheral fibers of both orientations also exist. Light micros- copy of the extraglandular duct demonstrated circumferential fibers near the basement membrane and longitudinal and angular elastic fibers amid the collagenous layers. Some of the longitudinal fibers assume a loose cross-weave. Intraglandularly, as duct size diminishes elastic fibers progressively decrease in number and size until the smallest ducts have none. Thus, an elastic gradient exists. It is believed that recoil of the angular elastic fibers aids distension of the large and medium ducts when secretion is great and that recoil of the circumferential ones permits those duct diameters to diminish when secretion does. The longitudinal elastic fibers would allow all but the smallest ducts to recoil from the stretching of much of the exorbital lacrimal duct system accompanying blinking and other facial movements.
    [Show full text]
  • 707 the Cell-Elastin-Elastase(S) Interacting Triade Directs Elastolysis W
    [Frontiers in Bioscience 16, 707-722, January 1, 2011] The cell-elastin-elastase(s) interacting triade directs elastolysis William Hornebeck, Herve Emonard Universite de Reims Champagne-Ardenne, UMR 6237 CNRS, Faculte de Medecine, 51 rue Cognacq Jay, 51095 Reims Cedex, France TABLE OF CONTENTS 1. Abstract 2. Introduction 3. Human elastases: definition, classification and properties 3.1. Serine peptidases 3.2. Cysteine peptidases 3.3. Metallopeptidases 4. Mechanism of elastolysis 4.1. Adsorption of elastases onto elastin 4.2. Ex vivo degradation of elastin by elastases 4.3. Cell-directed elastolysis 5. Elastin peptides as potent matrikines 5.1. The elastin-receptor complex 5.2. Dualism in elastin peptide properties 6. Role of fatty acids and heparin(s) in the control of elastases 7. Concluding remarks 8. Acknowledgements 9. References 1. ABSTRACT 2. INTRODUCTION Human elastases have been identified within Fragmentation of elastic fibers is a hallmark of serine, cysteine and metallopeptidase families. These cardio-vascular diseases (1, 2) and emphysema (3). It is enzymes are able to adsorb rapidly onto elastin, but they also observed in skin during intrinsic ageing (4) and can also bind onto cell surface-associated proteins such as melanoma progression (5). These alterations are attributed heparan sulfate proteoglycans, both interactions involving to the action of proteases designated as elastases. Elastases enzyme exosites distinct form active site. Immobilization of are defined as endopeptidases that can generate soluble elastin at the cell surface will create a sequestered peptides from elastin (6). Such a definition excludes microenvironment and will favour elastolysis. Generated proteases able to cleave only a few peptide bonds within elastin peptides are potent matrikines displaying dual the polymer but lacking the ability to release peptides to biological functions in physiopathology that are described appreciable extent.
    [Show full text]
  • Connective Tissue Learning Objectives * Understand the Feature and Classification of the Connective Tissue
    Connective Tissue Learning objectives * Understand the feature and classification of the connective tissue. * Understand the structure and function of varied composition of the loose connective tissue. * Know the composition of the matrix. * Know the features of fibers. * Know the composition of the ground substance. * Know the basic structure and function of the dense connective tissue, reticular tissue and adipose tissue. General characteristic: - Connective tissue is formed by cells and extracellular matrix (ECM). - It differ from the epithelium. - It has a small number of cells and a large amount of extracellular matrix. - The cells in C. T have no polarity. That means they have no the free surface and the basal surface. - They are scattered throughout the ECM. - The extracellular matrix is composed of . fibers ( constitute the formed elements) , an . amorphous ground substance and . tissue fluid. - Connective tissue originate from the mesenchyme, which is embryonal C. T. The cells have multiple developmental potentialities. They have the bility to differentiate different kinds of C. T cells, endothelial cells and smooth muscle cells. - Connective tissue forms a vast and continuous compartment throughout the body, bounded by the basal laminae of the various epithelia and by the basal or external laminae of muscle cells and nerve-supporting cells. - Different types of connective tissue are responsible for a variety of functions. Functions of connective tissues: The functions of the various connective tissues are reflected in the types of cells and fibers present within the tissue and the composition of the ground substance in the ECM. - Binding and packing of tissue ……….CT Proper; - Connect, anchor and support………...Tendon and ligament; - Transport of metabolites……………..Through ground substance; - Defense against infection…………….Lymphocytes, macrophages; - Repair of injury……………………….Scar tissue; - Fat storage…………………………… Adipose tissue.
    [Show full text]
  • The Microfibril-Elastin Fiber System Distribution in Left Atrioventricular Valve of the Rat
    Int. J. Morphol., 29(3):907-913, 2011. The Microfibril-Elastin Fiber System Distribution in Left Atrioventricular Valve of the Rat Distribución del Sistema de Microfibrillas y fibras de Elastina en la Valva Atrioventricular Izquierda de la Rata *Vinícius Novaes Rocha; *Rodrigo Neto-Ferreira; **Carlos Alberto Mandarim-de-Lacerda & *Jorge José de Carvalho ROCHA, V. N.; NETO-FERREIRA, R.; MANDARIM-DE-LACERDA & CARVALHO, J. J. The microfibril-elastin fiber system distribuition in left atrioventricular valve of the rat. Int. J. Morphol., 29(3):907-913, 2011. SUMMARY: The microfibril-elastin fiber system, an important constituent of the extracellular matrix, was studied in the rat left atrioventricular valve to investigate the interrelationship of oxytalan, elaunin and elastic fibers in left atrioventricular valve morphology. The elastin fibers forms continuous bundles observed along the length of the valve in atrial and ventricular layers and oriented parallel to endothelium. The elaunin and oxytalan fibers are distributed in the thickest fiber bundles along the length of the valve. The thinner fibers which radiated towards both the atrial and spongiosa layers, either as isolated or arborescent fiber bundles were identified as oxytalan fibers. With transmission electron microscopy elastic fibers were seen mainly in the atrial layer. The spongiosa layer was composed of elaunin and oxytalan fibers and ventricular layer showed elaunin fibers arranged in continuous bundles parallel to the endothelium. Both fibrillin and elastin were seen and identified by immunocytochemistry with colloidal gold in the left atrioventricular valve spongiosa and atrial layers. These observations allow us to suggest that the microfibril-elastin fiber system plays a role in the mechanical protection and maintenance of the integrity of the rat left atrioventricular valve.
    [Show full text]
  • Morphological and Morphometric Study of Collagen and Elastic Fibers of the Gastroduodenal Junction of Adult and Old Wistar Rats
    Original article Morphological and morphometric study of collagen and elastic fibers of the gastroduodenal junction of adult and old Wistar rats Brito, MC.1,2*, Cury, DP.1,3, Barbosa, ACS.1,2, Silveira, MP.1,4 and Chopard RP.1,2 1Department of Surgery, Faculty of Veterinary Medicine and Animal Science, University of São Paulo – USP, Av. Prof. Dr. Orlando Marques de Paiva, 87, CEP 05508-270, São Paulo, SP, Brazil 2Laboratory of Cellular Biology and functional Anatomy, Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo – USP, Av. Prof. Lineu Prestes, 2415, CEP 05508-900 São Paulo, SP, Brazil 3Laboratory of Cell and Tissue Ultrastructure, Department of Anatomy, Institute of Biomedical Science, University of São Paulo – USP, Av. Prof. Lineu Prestes, 2415, CEP 05508-900, São Paulo, SP, Brazil 4Laboratory of Neurogastroenterology, Department of Anatomy, Institute of Biomedical Science, University of São Paulo – USP, Av. Prof. Lineu Prestes, 2415, CEP 05508-900, São Paulo, SP, Brazil *E-mail: [email protected] Abstract The aim of this work was to analyze the elastic fibers and collagen fibers of the gastroduodenal junction in rats at different ages. Through histomorphometric search, data on changes in connective tissue due to aging were obtained in order to understand its anatomical and functional relationships. Materials and Methods: We used 34 male rats divided into two groups: adult (03 months) and old group (18 months). To observe the connective tissue fibers of gastroduodenal junction, conventional histological techniques were applied and stained with the Verhoeff’s iron hematoxylin and Weigert’s resorcin fuchsin; Weigert’s resorcin fuchsin after oxidation with 1% aqueous solution of oxone, Picrosirius and hematoxylin-eosin.
    [Show full text]