Dermis Ageing

Path. Res. Pract, 178, 515-517 (1984)

Dermis Ageing H. Bouissou Service d'Anatomie Pathologique (Pr. H. Bouissou), Toulouse, France

M. Th. Pieraggi and M. Julian Chargee de Recherches au C.N.R.S., Toulouse, France

SUMMARY

On ageing majorchanges within connective components of the dermis can be seen: collagen looses its regular and fascicular appearance, while groundsubstance increases, elastic material decreases and the fibroblast cell population becomes "at rest,,2-5, 10. The resulting dermal ageing is different according to individuals and is related to genetic back ground and exposition to multiple aggressions. This review presents these changes of thesuperficial dermis andthe role of fibroblasts in the conservation of the connective tissue integrity.

Dennis of Young Adults In the dermis, the papillary part was only examined since the more inportant lesions were developed in this

area. With light microscopy the dermis of young adults showed the presence of numerous elastic fibers, leaving the parallel network and reaching the epidermis. They were regularly distributed and clung to the dermal epidermal junction. The thick, well organized collagen bundles were remained closely packed. Sirius Red stain enhanced the preponderance of collagen lover collagen III (the collagen I appeared stained in red, orange or yellow, the collagen III being green). This observation was in agreement with Fleischmajer's (1980) and Meigel's (1977) results, where the skin type III collagen represented about 16 th of the total collagen and the type I at least 80% of the total dermal collagen. This aspect of the young skin corresponds to normal skin or "type 0" skin. © 1984 by GustavFischer Verlag, Stuttgart

Using immunofluorescence, fibronectin co-distributed with collagen fibrils was shown to be abundant forming a papillary network and a reticular pattern in the lower zone. The immunofluorescent staining was enhanced in dermal epidermal junction and around vessels. By scanningelectron microscopy, groups of thick regular and well oriented collagen bundles were observed. They were lightly waved and generally assembled the ones to the others in a parallel way. However in the papillary dermis, some bundles were thin and small. Transmission electron microscopy revealed dense, thick and voluminous collagen bundles. The narrow spaces between collagen fascicles contained cellular extensions, variable amounts of mature elastic fibers and matrix (proteoglycans-glycosaminoglycans). The collagen fibers had regular diameter and characteristic periodicity of about 64 nm. The essential element of the dermic connective tissue was the fibroblast. The cell was in close contact with collagen fascicles. It was an elongated, often enlarged stel0344-0338/84/0178-0515$3.50/0

516 . H. Bouissou, M. Th. Pieraggi and M. Juhan

lated cell with thin extensions . In its most inflated part, was observed an oval central nucleus with a prominent nucleolus. The fibroblasts appeared as active and secreting cells. Their most notable characteristic was the presence of a well developed rough endoplasmic reticulum and a prominent Golgi complex. Variable numbers of mitochondria, mono and polyribosomes were also seen. The amount of ergastoplasm appeared in relation with the secretory activity of the cell. The endoplasmic reticulum filled the cytoplasm almost entirely and contained more or less distented profiles with floculent pale material. The cytoskeleton of these cells was made of a fine network of rnicrofilaments visible throughout the cytoplasm. They were grouped in small bundles at a periphery of nuclei but were predominant in the vicinity of secretory areas. In young subjects dermis was composed by compact collagen bundles. The fibroblast was an active cell, in close contact with collagen bundles.

Dennis of Ageing Adults With ageing, the dermis was modified.

By light microscopy, the modifications were characterized by the slow disappearance of the papillary elastic network and by morphological changes of collagen bundles. The latter lost its typical fascicular pattern and become granular. So we can describe two degrees in ageing: skin of type I was characterized by a decrease of the number of elastic fibers but elastic fibers were seen from place to place and reached the epidermic membrane; skin of type II with complete disappearance of the elastic tissue associated with desorganization of the collagen bundles. With Sirius Red stain, the intense yellow orange staining of the dermis confirmed the predominance of type I collagen. Scanty amounts of type III collagen were also demonstrated as small fascicles immediately in the vicinity of epidermis. This is actually explained by the looser consistancy of papillary dermis (since it has been shown that there was no quantitative variation of the amount of collagen along the life). By immunofluorescence, the papillary network of fibronectin was less developed as revealed by investigation using the antifibronectin antibody, particularly there was a decrease of papillary network. The fluorescence staining was only seen around capillaries and in the dermal epidermal junction. By scanning electron microscopy, superficial dermis appeared disordered. The collagen bundles were irregular in shape and had a rough surface, they were thin and often separated by conspicuous interfibrillar spaces. Transmission electron microscopy showed short and thin fascicles of collagen fibers, separated by empty spaces corresponding to ground substance. With high resolutions

most of the fibers had a normal structure with a characteristic periodicity. However, a few number of fibers did not show the typical periodicity (this latter was shaded) moreover their extensions appeared to separate forming microfibrils giving a "bruched" aspect. Elastic fibers were not seen in the ageing papillary dermis. Fibroblast was a flattened and less elongated cell. Its cytoplasm was poor in rough endoplasmic reticulum and ribosomes, numerous dense bodies of lysosomial type and frequent membran bound lipid vacuoles were obseved. But the main modification of this cell consisted of disorganization of cytoskeleton: it was characterized by voluminous fascicles or bundles which occupied large cytoplasmic areas, often in contact with mitochondrias, but without any relation with the plasma membrane. The fibroblast lost its secretory function and became a "quiescent" cell. The close association between collagen fibers and fibroblasts was not readily seen and consequently the cell population was isolated within the interstitial matrix!', The fragmentation of collagen fibers, the absence of elastic material, the occurence of quiescent fibroblasts without any direct contact with collagen fascicles represent the morphologic changes of ageing dermis. So with ageing, two major morphologic modifications can be described: the loss of fibroblast collagen bundle contact and the changes of the cytoskeleton architecture. The decrease of dermal fibronectin in subjects aged 60 to 75 may explain these two lesions indeed, recent studies having established the presence of binding site between alpha chain of collagen and fibronectin and between actin and fibronectin chain also" 8, 9, 11, 14-16. In our study the loss of cell matrix adhesion in old individuals associated to a decrease of fibronectin suggest that this glycoprotein is an important factor to assume the integrity of cell collagen adhesion. In our investigation, the cytoskeleton architecture changes, already shown in cultured fibroblasts with the gradual ageing of culture, can be interpreted as the result of a drecrease in oxygen consumption and of an ATP reduction observed during senescence1, 12. Consequently knowing the essential role of cytoskeleton in the migration and the excretion of secretions, it can be postulated that the cytoskeleton changes observed in old fibroblasts could represent a deficiency in procollagen transport within the cell, an altered secretory process and a loss of relationship with fibronectin. In conclusion, it could be suggested that dermal ageing is consequent to a dysfunction of the cell interstitial matrix unit in which fibronectin, cytoskeleton and plasma membrane are deeply involved. The resulting progressive morphologic destabilisation correlate with the alterations of fibroblastic metabolism, particularly the protidic moiety. If we have a better understanding about mechanisms involved in the ageing of the cell and its dysfunction, endogenous agents to the inductive process are still poorly known.

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References 1 Bershadsky AD, Gelfand VI, Svitkina TM , Tint IS (1980) Destruction of microfilaments bundles in mouse embryo fibroblasts treated with inhibitors of energy metabolism. Exp Cell Res 127: 421-429 2 Bouissou H, Fabre MTh , Julian M, Rumeau JL, Huron R (1970) La biopsie cutanee permet-elle de connaitre l'etat de la paroi vasculaire? Rev Europ Et Clin BIOI 15: 444--453 3 Bouissou H, Pieraggi MTh , Julian M (1971) Le fibroblaste cutane au cours du vieillissement et de certa ins etats pathologiques. Ann Anat Path 16: 373-386 4 Bouissou H, Pieraggi MTh , Julian M, Douste-Blazy L (1973) Cutaneous ageing; its relation with arteriosclerosis and atheroma. Front Matrix Bioi 1: 190-211 5 Bouissou H, De Graeve J, Solera ML, Thiers JC, Wulfert E, Enjalbert A, Puel P (1981) Apoproteine B et cholesterol cutanes et seriques, Paroi Arterielle/Arterial Wall 7: 22-28 6 Engvall E, Ruoslahti E (1977) Binding of soluble form of fibroblast surface protein, fibronectin , to collagen. Int J Cancer

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7 Fleischmajer R, Gay S, Perlish J, Cesarini JP (1980) Irnrnunoelectron microscopy of type 1II collagen in normal and scleroderma skin. J Invest Dermatol 75: 189-191

8 Keski OJ, Sen A, Todaro GS (1980) Direct association of fibronectin and actin molecules in vitro. J Cell Bioi 85: 527-533 9 Mc Donagh J (1981) Fibronectin a molecular glue. Arch Pathol Lab Med 105: 393-396 10 Meigel WN, Gay S, Weber L (1977) Dermal architecture and collagen type distribution. Arch Dermatol Res 259: 1-10 11 Mosher DF, Furch TLT (1981) Fibronectin: review of its structure and possible functions . J Invest Dermatol 77: 175-180 12 Pena SDJ (1980) A new technique for the visualization of the cytoskeleton in cultured fibroblasts with cooma ssie blue R 250. Cell Bioi Intern Rep 4: 149-153 13 Pieraggi MTh, Julian M, Bouissou H (1984) Fibroblast changes and cutaneous ageing. Virchow Archiv. A (in press) 14 Ruoslahti E, Engvall E, Hayman EG (1981) Fibronectin : current concepts of its structure and functions. Coli Res 1: 95-128 15 Ruoslahti E, Pierschbacher M, Engvall E, Oldberg A, Hayman EG (1982) Molecular and biological interactions of fibronectin. J Invest Dermatol 79: 655-685 16 Vogel KG, Kelley R, Stewart C (1981) Loss of organized fibronectin matrix from the surface of aging diploid fibroblast. Mech Ageing and Develop 16: 295-302

Received September 12, 1983 . Accepted October 31, 1983

Key words: Dermis ageing. H. Bouissou, Service d'Anatomie Pathologique, C.H.U. Rangueil, Chemin du Vallon F-31054 Toulouse Cedex.