Quantitative changes in skin collagen in morphoea

Osteoporosis, a unitary hypothesis of collagen loss in skin and bone

Progress in osteoporosis has been stultified by repetitive, statistic-driven studies and catechistic reviews; in the absence of concept and hypothesis research is aimless, and the trivial associations it continually reveals, has led to the cul-de-sac of multifactorialism. A return to hypothesis-led research which seeks major causal defects and the conclusive therapies that arise from them is essential. The hypothesis proposed evolved from research into the mechanism of senile purpura. This predicted a causal loss of skin collagen that was contrary to contemporary opinion, but was confirmed when collagen was expressed absolutely, instead as a percentage or ratio: women have less collagen than men and it decreases by 1% a year in exposed and unexposed skin. Corticosteroids (which also produce shear purpura) reduce skin collagen and androgen and virilism increase it; growth hormone produces the greatest increase, and there is a decrease in hypopituitarism. All these changes in skin collagen correspond to changes in bone density, and the circumstances are too various for coincidence. This led to the hypothesis that the changes found in skin collagen also occur in bone collagen, leading to the associated changes in bone density; thus a loss of collagen in skin and bones with aging is the causal counterpart to loss of bone density in senile osteoporosis. If this is correct then, as with aging, androgen and virilisation, corticosteroids, growth hormone and hypopituitarism, changes in bone density should correspond to systemic changes in skin collagen. This correspondence is found to occur in osteogenesis imperfecta and Ehlers-Danlos syndrome, two genetically discrete families of disordered collagen production, and other situations, e.g., scurvy and homocystinuria. A primary loss of collagen in osteoporotic bones is an essential prediction of the hypothesis; in fact this loss is well established but, inexplicably, it has been assumed to be secondary to the bone loss. Because of the comparable changes in skin and bones, the hypothesis implies that skin collagen could be used to predict the state of the bones and their response to treatment. It also implies androgen should be an effective treatment of osteoporosis, and growth hormone even more effective (likewise, of course, skin aging). More importantly, skin collagen and the production of collagen by skin fibroblasts could be used for the assay and industrial development of more potent, if not less toxic treatments and prevention of loss of bone (and skin) substance.

Quantification of cutaneous sclerosis with a skin elasticity meter in patients with generalized scleroderma

BACKGROUND

The skin score, a subjective assessment of skin elasticity, is widely used in patients with systemic sclerosis. Although this scoring method is regarded as a validated and accepted tool, the interobserver and intraobserver reproducibility is relatively poor.

OBJECTIVE

Our purpose was to investigate whether the recently developed SEM 474 cutometer, which exerts a controlled vacuum force to the skin, can measure skin elasticity more objectively than the skin score.

METHODS

Skin elasticity was measured in 74 different body areas in patients with systemic sclerosis and compared with the skin score obtained from the same areas.

RESULTS

The cutometer produced quantitative and reproducible data. A large-diameter (8 mm) measuring probe was superior to a small probe. The interobserver intraclass correlation coefficient (ICC) was 0.92; the intraobserver ICC was 0.94. A linear correlation was found with the clinical skin score; the Spearman rank correlation test was 0.69.

CONCLUSION

The correlation with the skin score was reasonable, despite the observation that regional differences in skin elasticity were detected by the cutometer but not by the human observer, who automatically compensates for these factors and integrates them into the skin score. The high interobserver and intraobserver ICC makes the cutometer more suitable for quantifying changes in skin thickness than the subjective skin score.

Skin thickness and collagen content in progressive systemic sclerosis and localized scleroderma

Skin biopsies of uniform location and surface area (7 mm diameter) were obtained from the extensor aspect of the forearm of 147 patients with progressive systemic sclerosis (PSS) (107 with diffuse scleroderma, 40 with the CREST syndrome variant) and 58 individuals with normal skin. After careful removal of all subcutaneous fatty tissue, the skin cores were weighed and their water and hydroxyproline content determined. Despite recent claims to the contrary, it was found that there is a marked and highly significant increase in the thickness of the skin during the indurative phase of PSS, and that this is associated with a proportionate increase in total dermal collagen content. A similar degree of thickening was found in the skin of patients with eosinophilic fasciitis and acromegaly. A close correlation was observed between clinical estimation of the degree of skin thickening and the weight of the skin biopsy cores. Change in the weight of skin cores was observed during the course of illness of the patients with PSS and may serve as a useful measurement of alteration in the degree of skin thickening.

The influence of age and sex on skin thickness, skin collagen and density

Forearm skin collagen, dermal thickness and collagen density were measured in a large number of normal subjects as a standard reference for future studies. Skin collagen decreased with age and was less in the females at all ages. There is a direct relationship between skin collagen and dermal thickness but variations in collagen density in disease limit the use of dermal thickness as a guide to changes in its collagen content.

Skin collagen and thickness in simple obesity

The effects of stretching of the skin on its collagen content and thickness have been studied in a group of subjects with chronic obesity. Despite the increase in skin surface a normal skin thickness, collagen content, and density were maintained. It is concluded that the skin stretching induced by prolonged obesity led to hypertrophy of collagen and that this had maintained both skin thickness and collagen content. It is not known whether this is due to enhanced synthesis or decreased degradation.

Osteoporosis, skin collagen, and androgen

Total skin collagen was found to be decreased in untreated patients with osteoporosis, particularly women, but increased after treatment with androgens in women. Decreased body collagen may possibly be a primary defect in osteoporosis, while androgens may increase total skin collagen.

Skin collagen and thickness in women with hirsuties

Total skin collagen is greatly increased in women with hirsuties. This is presumably due to androgen, whether locally produced or circulating.