Age-related skin changes

Med Pregl 2012; LXV (5-6): 191-195. Novi Sad: maj-juni. 191 ORIGINALNI NAUČNI RADOVI ORIGINAL STUDIES Clinical Center of Vojvodina, Novi Sad Center for Pathology and Histology Originalni naučni rad Original study UDK 616.5-001.15-091.8 DOI: 10.2298/MPNS1206191L AGE-RELATED SKIN CHANGES STAROSNE PROMENE NA KOŽI Aleksandra LEVAKOV, Nada VUČKOVIĆ, Matilda ĐOLAI, Mihaela MOCKO KAĆANSKI and Snežana BOŽANIĆ Summary – Age-related skin changes can be induced by chronological ageing, manifested in subcutaneous fat reduction, and photo-ageing eliciting increased elastotic substance in the upper dermis, destruction of its fibrilar structure, augmented intercellular substance and moderate inflammatory infiltrate. Forty-five biopsy skin samples of the sun-exposed and sun-protected skin were analyzed. The patients were both males and females, aged from 17 to 81 years. The thickness of the epidermal layers and the number of cellular living layers is greater in younger skin. The amount of keratohyaline granules is enlarged in older skin. Dermoepidermal junction is flattened and the presence of elastotic material in the dermis is pronounced with age. The amount of inflammatory infiltrate is increased, the fibrous trabeculae are thickened in older skin and the atrophy of the hypodermis is observed. Chronological ageing alters the fibroblasts metabolism by reducing their life span, capacity to divide and produce collagen. During ageing, the enlargement of collagen fibrils diminishes the skin elasticity. Key words: Skin Aging; Skin + physiopathology; Adolescent; Adult; Middle Aged; Aged; Female; Male; Ultraviolet Rays; Sunlight + adverse effects; Collagen; Elastic Tissue; Dermis; Epidermis Introduction The skin provides a large body interface with the environment that change with ageing. These changes begin before thirty and are developed by lifestyle and sun exposure. Skin ageing results from two processes: chronological ageing and photo-ageing [1-3]. Intrinsic ageing is a naturally occurring process that results in slow tissue degeneration [2]. Its features are: atrophy of the dermis due to the loss of collagen, degeneration in the elastic fiber network and reduced hydration [2]. Skin ageing changes can be manifested in atrophy of the lower dermis and reduction of subcutaneous fat. Photo-ageing of the skin results from the advanced cumulative effects of ultraviolet (UV) radiation leading to increased elastotic substance in the upper dermis, destruction of its fibrilar structure, augmented amount of intercellular substance and moderate inflammatory infiltrate. Ageing alters the metabolism of fibroblasts by reducing their lifespan as well as their capacity to divide, and produce collagen. During ageing, the proportional reduction in large proteoglycans (chondroitin-sulfate), along with simultaneous increase in small proteoglycans (dermatan-sulfate), causes intensified synthesis of collagen fibrils and their enlargement, which diminishes the skin elasticity. Wound healing is affected by systemic factors (endocrine, metabolic, nutrition etc.) and local disorders (vascular, neurological). Ageing is connected with the decrease in fibronectin at the site of a scar, delayed inflammatory response and re-epithelization. On the contrary, healing in the young produces dense and firm scars. The speed of healing is increased at the expense of the scar quality, probably due to an altered inflammatory response. Dermal blood vessels changes can compromise inflammatory reaction at the injury spot. Raised amounts of elastin II and fibrillin affect the proximal dermal blood vessels, restore the structure of papillary dermis and improve healing. Extrinsic ageing is a result of environmental factors, principally ultraviolet exposure. The distinguishing feature of photo-ageing is a massive accumulation of elastotic material in the upper and middle dermis, a process termed solar elastosis [2]. The effects of UV on the skin are inevitable and this is scarcely surprising as the skin contains many cells as well as subcellular chromophores which are capable of absorbing energy within the UV spectrum. Cellular chromophores include keratinocytes, melanocytes, dermal fibroblasts, Langerhans and mast cells. Subcellular chromophores include keratin, melanin, collagen, elastin, lipids and steroids [3,4]. Chronic photodamage of the skin manifests itself as extrinsic skin ageing (photo-ageing) and photocarcinogenesis. Deoxyribonucleic acid (DNA) photodamage and UV-generated reactive oxygen species (ROS) are the initial molecular events leading to the typical histological and clinical manifestations of chronic photodamage of the skin [4]. The exposure Corresponding author: Asist. mr sc. med. Aleksandra Levakov, Centar za patologiju i histologiju, 21000 Novi Sad, Hajduk Veljkova 1-7, E-mail: [email protected] 192 Abbreviations UV – ultraviolet rays DNA – deoxyribonucleic acid DCs – Dendritic cells LCs – Langerhans cells IL – interleukine UVB – ultraviolet B rays of human skin to environmental and artificial UV irradiation has increased dramatically. The reason for increased solar UV irradiation is not only the stratospheric ozone depletion but also the very popular although unjustified visits to the tanning salons to get ”suntan”. In addition, travelling to equatorial regions gives its contribution to the individual annual UV damage [5]. The long-term detrimental effects caused by energy absorption of UV photons are immuno-suppression and skin cancer, but the photo-oxidative damage leads to quantitative and qualitative alterations of cells and structural macromolecules of the dermal connective tissue responsible for tensile strength, resilience and stability of the skin. The clinically manifesting results of UV induced damage are wrinkles, skin laxity, leathery appearance, sensitivity, impaired wound healing capacities and higher vulnerability of skin [5]. Previous studies have described changes in epidermis, which becomes thinner during chronological ageing. The thickness of human skin and epidermis is variable, depending on their localization. Thinning is worse at the deepest portions of wrinkles, with or without reduction in the number of cellular layers [6]. The decrease in epidermal thickness corresponds to the reduction in number of cellular layers. On the other hand, stratum corneum of the wrinkle is thickened by the accumulation of corneocytes forming a horny plug. Keratohyaline granules are more abundant in stratum granulosum of the flanks than at the bottom of the wrinkle [6]. The dermoepidermal junction becomes flattened during ageing. This shape is a result of disappearing dermal papillae and epidermal buds. During ageing, the dermis becomes atrophied due to the reduction in collagen and some glycosaminoglycans and so does the adipose tissue of hypodermis. These reductions lead to wrinkle formation. Atrophy of the hypodermis with fibrous trabeculae thickening is the most intense under the wrinkle itself. In photodamaged skin, the elastic tissue in the reticular dermis undergoes marked proliferation named actinic elastosis. This elastotic tissue forms real pads on each side of the wrinkle and vanishes at the bottom of the wrinkle. There is a severe decrease of oxylatan fibers forming a Grenz zone in papillary dermis. Fibrillin microfibrilar network of the papillary dermis is particularly susceptible to degradation by UV irradiation and results in depletion and re-organization of fibrillin in dermoepidermal junction [6]. The most important function of dendritic cells (DCs) is their ability to activate T cells and induce their proliferation. By producing cytokines and chemokines, the DCs modify the survival of immune effectors. Levakov A, et al. Age-related skin changes They play a crucial role in initiating and regulating immune responses so they can be directly involved in altered antitumor immunity with ageing. Immune function declines with ageing in contrast to increased susceptibility to infections, malignancies and autoimmune diseases. Both T and B cell immune responses are dramatically affected by ageing. DCs are present in non-lymphoid peripheral tissues where they recognize environmental antigens. They play a key role in maintaining the host integrity through the host defense and immunity. A linear decrease in DCs, including Langerhans cells (LCs), might reduce immunosurveillance in the aged skin. In addition to the reduction in their number, Langerhans cells themselves show morphological signs of atrophy with only few dendrites and several Birbeck granules (BGs). These morphological changes are associated with the loss of DC functions, and contribute to the age-associated development of skin cancer. The number of DCs, their distribution, and development from hematopoietic precursors CD (cluster of differentiation) 34+ are markedly inhibited in the elderly. Currently, 60% of all neoplasm occur in persons aged 65 years and older. A significant decrease in DCs with ageing reduces the capacity for generating efficient anti-infectious and antitumor immune responses. The DC system is significantly impaired in the tumor microenvironment and usually manifests as decreased dendropoiesis and DC maturation, suppressed ability of DCs to produce interleukin (IL)-12, increased synthesis of IL-10, inability to induce T cell proliferation and shortened survival of DCs [7]. Material and Methods We analyzed skin structure in biopsies perfor med for various pathologic changes (nevus, basal cell carcinoma, actinic keratosis, sqaumous cell carcinoma, hemangioma etc.). Histological slides were routinely prepared at Pathology and Histology Centre, Clinical Center of Vojvodina, Novi Sad. Surgical material was fixed in formalin. Paraffin embedded tissue sections of 5-7μ were further stained with hematoxylin-eosin and observed at low and high light microscope magnification. Masson’s trichrome staining serves for showing collagen fibers, whereas orcein dye is for elastotic material. Alcian bluePAS shows glycogen content. Forty-five biopsy samples were observed from various body regions (frontal, face, parietal, neck, abdominal, back, lumbar, gluteal, limbs). The patients were of both genders, their age ranging from 17 to 81 years. The intact skin next to a pathological change was under observation. Two groups of patients were analyzed: specimens of the sun exposed skin and specimens of the sun protected skin. The patients were categorized according to their age. Med Pregl 2012; LXV (5-6): 191-195. Novi Sad: maj-juni. The obtained results were processed with respect to quality and quantity and the taken images were also analyzed. All these parameters were counted manually by one examiner. The following paramters were observed: – thickness of the epidermal layers, – number of cellular living layers in epidermis, – horny plug formation, – amount of keratohyaline granules in stratum granulosum, – shape of dermoepidermal junction, – presence of elastotic material in the upper and middle dermis, – atrophy of the adipose tissue in hypodermis, – amount of inflammatory infiltrate, – thickness of fibrous trabeculae. Results Various body regions in both groups of patients showed different changes. Specimens of the sun exposed skin (frontal, face, parietal, neck, back, limbs) and specimens of the sun protected skin (abdominal, lumbar, gluteal) were analyzed. The patients were divided into two age groups: from 17 to 49 and from 50 to 81 years. The following parameters were reported in the skin specimens from the older group: – flattened shape of dermoepidermal junction (Figure 1) – number of cellular living layers in epidermis is reduced (Figure 2) – accumulation of keratohyaline granules in stratum granulosum (Figure 3) – presence of elastotic material in the dermis is pronounced with age (Figure 4) – atrophy of the adipose tissue in hypodermis is observed with ageing – a mount of perivascular inflammatory infiltrate is slightly raised (Figure 5) 193 Fig. 2. Reduction in number of living cell layers of epidermis, age 78, head parietal (HE, x 40) Slika 2. Smanjen broj slojeva živih ćelija epidermisa, 78 godina, poglavina parijetalno (HE, x 40) Fig. 3. Accumulation of keratinized cells, age 78, neck (HE, x 40) Slika 3. Nagomilavanje keratinizovanih ćelija, 78 godina, vrat (HE, x 40) Fig. 1. The flattened shape of dermoepidermal junction in older skin, age 69, face (HE, x 40) Slika 1. Zaravnjena dermoepidermalna granica u starijoj koži, 69 godina, lice (HE, x 40) – thickness of fibrous trabeculae is observed in the aged skin The following changes were recorded in the skin specimens from the younger age group: – greater thickness of the epidermal layers – number of cellular living layers in epidermis is greater 194 Fig. 4. Dermal accumulation of abnormal elastic fibers, age 82, lumbar (orcein, x 20) Slika 4. Nakupljanje elastičnih vlakana u dermisu, 82 godine, lumbalno (orcein, x 20) Fig. 5. Dermis contains inflammatory infiltrates, mostly perivascular and perifollicular, age 69, face (HE, x 10) Slika 5. Inflamatorni infiltrat u dermisu smešten perivaskularno i perifolikularno, 69 godina, lice (HE, x 10) – shape of dermoepidermal junction is more wavelike – small amount of elastotic material in the dermis – larger amount of the adipose tissue in hypodermis – slight amount of inflammatory infiltrate. The horny plug formation depends on the site of the skin, and is not in correlation with ageing. Discussion Chronological ageing and photo ageing induce atrophy of all cutaneous structures with the exception of elastotic hypertrophy in dermis. This study showed a reduction in the number of living cell layers of epidermis. In addition, there was a disorder in the cell differentiation or desquamation process and the result was the accumulation of keratinized cells. Levakov A, et al. Age-related skin changes Collagen IV forms a dense network at the level of dermoepidermal junction. Its diminution could weaken this junction and compromise the mechanical stability of the skin itself. Some studies have shown that there is no significant alteration of collagen IV pattern in photodamaged skin; however, there is a significant reduction in it at the bottom of the wrinkles [6]. Collagen VII forms anchoring fibrils that stabilize binding of the basement membrane to the underlying papillary dermis. The number of anchoring fibrils in the photodamaged skin is lower than in the sun protected areas. The disappearance of collagen VI weakens the bond between the epidermis and dermis and contributes to the wrinkle formation [6]. Chondroitin-sulphates consolidate collagen fibers and participate in cutaneous hydration. They are also decreased during ageing [6]. Photo-ageing is associated with the accumulation of abnormal elastic fibers in the dermis due to decreased degradation and overproduction of elastic fibers. Separated material has been derived from disintegrated elastic fibers resulting from the long exposure to UV irradiation. Histological studies of chronically sun-exposed skin show that the dermis contains inflammatory infiltrates, mostly perivascular and perifollicular. Mast cells are more abundant in photodamaged skin than in the normal skin. They synthesize and release mediators which modulate directly or indirectly extra cellular matrix production and degradation [7]. Ultrastructural studies of the sun-exposed skin have also shown infiltration of the epidermis by macrophage (dendritic like cells), but with fewer Langerhans cells [1,8]. Ultraviolet B rays (UVB) irradiation has been reported to induce photo-ageing and suppress systemic immune function, thus leading to photocarcinogenesis [9]. The measurements have shown a significant increase in skin surface roughness and the loss of skin elasticity. The sample of the skin exposed to UVB irradiation exhibited a significant increase in epithelial keartins, elastins and metaloproteinases as well as the degradation of collagens (I,IV,VII) [10]. Several investigators have shown that exposure of the skin to UV induces leukocyte infiltration and elastase secreted by leukocytes or dermal fibroblasts [11]. Conclusion It is generally accepted that there are two different processes: chronological and photo-induced skin ageing, both being present in the sun exposed skin. The amount of chondroitin-sulphates that consolidate collagen fibers is reduced during the ageing process. The linear decrease in DCs, including LCs as well, might reduce immunosurveillance and lead to carcinogenesis in the aged skin. Infiltration of the epidermis by macrophages (dendritic-like cells), but with fewer Langerhans cells, was observed in the sun exposed skin, which could also contribute to the higher incidence of skin cancer. Med Pregl 2012; LXV (5-6): 191-195. Novi Sad: maj-juni. UVB exposed skin has a rough surface and loses its elasticity; it contains leukocyte infiltrates which release elastase, causing further skin damage. Knowledge of the ultravolet-absorbing chromophores in the skin and of the molecular mechanisms 195 leading to the unwanted effects of sun exposure provides the basis to develop novel strategies in the prevention and repair of photo-ageing. References 1. Rocquet C, Bonte F. Molecular aspect of skin ageing-recent data. Acta Dermatovenerol 2002;11(3):71-94. 2. Uitto J. The role of elastin and collagen in cutaneous aging: intrinsic aging versus photo exposure. J Drugs in Dermatol 2008;7 (2):12-6 3. Dalziel KL. Aspects of cutaneous ageing. Clin Exp Dermatol 1991;16(5):315-23 4. Fisher GJ, Kang S, Varani J, Bata Csorgo Z, Wan Y, Dattaet S. Mechanisms of photo aging and chronological skin aging. Arch Dermatol 2002;138:1462-70. 5. Ma W, Wlaschek M, Tantcheva-Poór I, Schneider LA, Naderi L, Razi-Wolf Z, et al. Chronological ageing and photo-ageing of the fibroblasts and the dermal connective tissue. Clin Exp Dermatol 2001;26(7):592-9 6. Content-Audonneau JL, JeanMarie C, Pauly G. A histological study of human wrinkle structures: comparison between sun-exposed areas of the face, with or without wrinkles, and sun-protected areas. Brit J Dermatol 1999;140:1038-47. 7. Milosavljević Z, Ljujić B. Produkcija humanog dermalnog ekvivalenta u in vitro uslovima. Med Pregl 2010;63(7-8):459-64. 8. Shurin MR, Shurin GV, Chatta GS. Aging and the dendritic cell system: implications for cancer. Crit Rev Oncol Hematol 2007;64:90-105. 9. Trautinger F. Mechanisms of photodamage of the skin and its functional consequences for skin ageing. Clin Exp Dermatol 2001; 26(7):573-7. 10. Hachiya A, Sriwiryanont P, Fujimura T, Ohuchi A, Kitahara T, Takema Y, et al. Mechanistic effects of long-term ultraviolet B irradiation induce epidermal and dermal changes in human skin xenografts. Am J Pathol 2009;174(2):401-13. 11. Muto J, Kuroda K, Wachi H, Hirose S, Tajima S. Accumulation of elafin in actinic elastosis of sun-damaged skin: elafin binds to elastin and prevents elastolytic degradation. J Invest Dermatol 2007;127(6):1358-66. Sažetak Uvod Starosne promene kože su rezultat: hronološkog procesa i kumulativnog dejstva UV zračenja. Materijal i metode Analizirani su isečci kože izloženi i zaštićeni od sunca, kod pacijenata oba pola, uzrasta 17–81 godina. Rezultati Debljina epidermisa i broj slojeva živih ćelija veći su u mlađoj koži. Starija koža sadrži više keratohijalinih granula i veću količinu keratinizovanih ćelija u epidermisu. Dermoepidermalna granica je zaravnjena, s izraženim elastotičnim metarijalom u dermisu. Inflamatorni infiltrat je povećan, a fibrozne trabekule su zadebljale u starijoj koži. Primetna je i atrofija hipodermisa. Zaključak Hronološko starenje oštećuje metabolizam fibroblasta skraćenjem njihovog života, kao i sposobnosti da se dele i proizvode kolagen. Tokom starenja se sa uvećanjem kolagenih vlakana smanjuje elastičnost kože. Starenje je udruženo sa smanjenjem količine fibronektina u ožiljku, zakasnelim inflamatornim odgovorom i reepitelizacijom tkiva. Starenjem opada funkcija imuniteta, nasuprot povećanoj podložnosti za infekcije, malignitete i autoimune bolesti. Ključne reči: Starenje kože; Koža + patofiziologija; Adolescenti; Odrasli; Srednjih godina; Stari; Žensko; Muško; Ultraljubičasti zraci; Sunčeva svetlost + neželjeni efekti; Kolagen; Elastično tkivo; Dermis; Epidermis Rad je primljen 22. VIII 2011. Prihvaćen za štampu 14. IX 2011. BIBLID.0025-8105:(2012):LXV:5-6:191-195.