老年皮肤的变化

老年皮肤的表皮与真皮变薄,表真皮交界处界面变平，黑素细胞和朗格汉斯细胞减少，真皮体积可减少205左右，皮肤附属器结构和功能发生改变和减退，致使表皮更替速率、修复速率变慢，对损伤的反应、屏障功能、清除化学物质速率、感觉功能、血管反应性、体温调节能力均有所下降，因此老年人易患皮肤干燥、瘙痒、色素改变（增加或减退）、大疱性类天疱疮以及各种增生性疾病等。     

Morphology of skin microvasculature in psoriasis

To establish the character of microvascular changes in psoriatic skin and their specificity, 29 skin biopsies of psoriatics (20 in exacerbation and 9 in a stationary stage) were investigated using histologic, histochemical, immunomorphologic, electron-microscopic, and morphometric methods. Five biopsies of uninvolved skin in scleroderma and five of diabetes mellitus patients were studied with the same technique for comparison. The results showed that structural changes depend on disease stage and the clinical appearance of lesions. Microvascular changes precede papule appearance during exacerbation and gradually increase during papule development. They comprise vascular dilatation, bridged fenestrations and gaps in endothelium, edematous areas in the cytoplasm of endotheliocytes, myocytes and pericytes, basement-membrane-zone thickening, and cell extravasation--signs of increased vascular permeability. Immunoglobulin G deposits in vascular walls, degranulation of mast cells, and extravasation of lymphocytes and neutrophils indicate that inflammation is a basic process during exacerbation and that immune mechanisms play an important role in the pathogenesis of inflammation. Microvascular changes in scleroderma and diabetes mellitus are different in nature and do not resemble those in psoriasis.     

PIXE analysis in uninvolved skin of atopic patients and aged skin.

PIXE (proton-induced X-ray emission) analysis was used to determine the elemental distribution in normal-appearing skin of patients suffering from atopic eczema and in the skin of elderly people. With this technique, elements with atomic numbers greater than or equal to 14 can be detected simultaneously in cryosections of skin biopsies down to a concentration of 1 ppm. Compared with a control group, the epidermal concentrations of Zn and Cu, which are constituent parts of a variety of enzymes, were increased in uninvolved skin of patients with atopic eczema. An increased concentration of these two metals might indicate that even in the epidermis of clinically normal skin of atopic patients, the content of certain enzymes is increased. In the epidermis of elderly people the level of K was lower and that of Ca was higher than in the epidermis of a younger age group. The decreased K level may reflect a reduction of the intracellular volume in the epidermis of aged skin. As high Ca concentrations inhibit the proliferation of and promote the differentiation of keratinocytes, elevated Ca levels may be of importance for the age-associated decrease in epidermal turnover rate.     

Modulation of skin collagen metabolism in aged and photoaged human skin in vivo.

To the best of our knowledge, no study has been conducted to date to directly compare the collagen metabolism of photoaged and naturally aged human skin. In this study, we compared collagen synthesis, matrix metalloproteinase-1 levels, and gelatinase activity of sun-exposed and sun-protected skin of both young and old subjects. Using northern blot analysis, immunohistochemical stain, and Western blot analysis, we demonstrated that the levels of procollagen type I mRNA and protein in photoaged and naturally aged human skin in vivo are significantly lower than those of young skin. Furthermore, we demonstrated, by northern blot analysis, that the procollagen alpha1(I) mRNA expression of photoaged skin is much greater than that of sun-protected skin in the same individual. In situ hybridization and immunohistochemical stain were used to show that the expression of type I procollagen mRNA and protein in the fibroblasts of photoaged skin is greater than for naturally aged skin. In addition, it was found, by Western blot analysis using protein extracted from the dermal tissues, that the level of procollagen type I protein in photoaged skin is lower than that of naturally aged skin. The level of matrix metalloproteinase-1 protein and the activity of matrix metalloproteinase-2 were higher in the dermis of photoaged skin than in naturally aged skin. Our results suggest that the natural aging process decreases collagen synthesis and increases the expression of matrix metalloproteinases, whereas photoaging results in an increase of collagen synthesis and greater matrix metalloproteinase expression in human skin in vivo. Thus, the balance between collagen synthesis and degradation leading to collagen deficiency is different in photoaged and naturally aged skin.     

A three‐dimensional skin equivalent reflecting some aspects of in vivo aged skin

Human skin undergoes morphological, biochemical and functional modifications during the ageing process. This study was designed to produce a 3‐dimensional (3D) skin equivalent in vitro reflecting some aspects of in vivo aged skin. Reconstructed skin was generated by co‐culturing skin fibroblasts and keratinocytes on a collagen–glycosaminoglycan–chitosan scaffold, and ageing was induced by the exposition of fibroblasts to Mitomycin‐C (MMC). Recently published data showed that MMC treatment resulted in a drug‐induced accelerated senescence (DIAS) in human dermal fibroblast cultures. Next to established ageing markers, histological changes were analysed in comparison with in vivo aged skin. In aged epidermis, the filaggrin expression is reduced in vivo and in vitro. Furthermore, in dermal tissue, the amount of elastin and collagen is lowered in aged skin in vivo as well as after the treatment of 3D skin equivalents with MMC in vitro. Our results show histological signs and some aspects of ageing in a 3D skin equivalent in vitro, which mimics aged skin in vivo.     

Smoking effect on skin wrinkling in the aged population

OBJECTIVES: Smoking causes premature wrinkling and is one of the more potent risk factors for atherosclerosis. The aims of the present study were to verify: (i) whether there is a difference between the wrinkling appearance in aged smokers and the nonsmoking population; and (ii) whether the systemic effects of smoking, such as atherothrombotic disease and cerebrovascular disease, are associated with a more striking appearance of wrinkling. PARTICIPANTS: Eighty volunteers (mean age, 76 years) were included in the study, 40 of whom were smokers and 20 of whom had suffered a stroke. RESULTS: The mean value of the wrinkling score measured for the smokers' group (stroke and nonstroke) was significantly higher than that for the nonsmokers' group (analysis of variance, ANOVA; P < 0.01). There was no significant difference between the smokers who had suffered from stroke and smokers who had not. CONCLUSION: The study indicated that prominent facial wrinkling was significantly more common among smokers than nonsmokers, not only in the relatively young but also among the aged population.     

Peptide-pro complex serum: Investigating effects on aged skin

Background

Effective anti-aging treatments are an unmet consumer need.

Aim

Ex vivoand clinical tests have evaluated the efficacy of a topical facial serum containing a proprietary blend of neuropeptides, proteins, amino acids, and marine extracts on aged skin.

Methods

In the ex vivo study the facial serum was compared to a commercially marketed face serum and to an untreated control on skin explants using microrelief, smoothness, and epidermal thickness endpoints. The 12 weeks monadic clinical study was designed for the test product to be used on the whole face. Subjects functioned as their own control; evaluating change from baseline. Skin was evaluated clinically by a Dermatologist for tolerability and for efficacy. Also part of the product assessment was skin hydration measurements, imaging, and a subject questionnaire.

Results

The facial serum improved skin condition by significant reductions in skin surface area occupied by microfolds and in skin roughness. Additionally, it increased epidermal thickness as compared to the untreated control as well as the commercially marketed face serum. The facial serum provided a statistically increased skin moisturization compared to pretreatment values. Dermatological evaluation of the skin concluded that there were statistically and clinically significant improvements in skin smoothness, wrinkles severity, fine lines visibility and lifting, and tightening effects at crow's feet area, forehead, and upper lip.

Conclusion

A facial serum, containing a proprietary blend of neuropeptides, proteins, amino acids, and marine extracts, has been shown to improve the overall quality of aged skin in a series of ex vivo and clinical tests.     

Collagen glycation triggers the formation of aged skin in vitro

Glycation products accumulate during the aging of many slowly renewing tissues, including skin. We have developed an in vitro model of chronologic aging of skin based on reconstructed skin modified by artificially glycating the collagen used to prepare the dermal compartment. The morphology of the modified skin is close to the morphology usually observed except that the dermis is altered in its fibrillar structure. Moreover, the analysis of skin markers revealed several unexpected biological and morphological modifications, which reflect in vivo aging and could be related to glycation per se. These include the activation of fibroblasts, increase of matrix molecules (collagen type III and collagen type IV) and metalloproteinase production (MMP1, MMP2 and MMP9), thickening of the basement membrane zone, and more strikingly, the modification of alpha6 and beta1 integrin patterns especially in epidermis, in a way closely resembling aged skin in vivo. We also found that these effects could be related to the production of putative diffusible factors by the dermal fibroblasts activated by glycation. Finally, we show that all these effects are likely to be glycation specific since they could be inhibited by aminoguanidine, a well-known glycation inhibitor. We conclude that the reconstructed skin model modified by glycation of the collagen closely mimics chronologic aging of skin in vivo. Taken together, these results strengthen the importance of glycation reactions in skin aging.     

The role of TRPV1 channel in aged human skin

Transient receptor potential vanilloid 1 (TRPV1) is a member of the nonselective cationic channel family. Activation of TRPV1 induces an influx of divalent and monovalent cations (i.e., Ca²⁺, Na⁺, and Mg²⁺) which are activated by capsaicin, heat, and acid. TRPV1 is known to be expressed in the epidermis, but little is known about the physiological significance and functional role of TRPV1 in skin.Recent studies suggested that heat- and ultraviolet (UV)-induced matrix metalloproteinases-1 (MMP-1) expression may be partly mediated by TRPV1 activation in human keratinocytes. Also, heat and UV increased expression of TRPV1 proteins in human skin in vivo. TRPV1 protein was expressed more in the sun-protected (upper-inner arm) skin of the elderly than in young subjects. In addition, the photoaged (forearm) skin of the elderly showed increased TRPV1 expression compared to sun-protected skin of the same individuals. The increased TRPV1 expression in the old skin implies that TRPV1 may be related to senile skin symptoms, such as senile pruritus and neurogenic inflammation. This review provides a summary of current researches on the role of TRPV1 channel in human skin, especially in aged skin.     

Maintaining skin integrity in the aged: a systematic review

Ageing is associated with structural and functional changes of the skin that result in increased vulnerability. The aim of this systematic review is to synthesize empirical evidence about the efficacy and effectiveness of basic skin care interventions for maintaining skin integrity in the aged. The databases Medline, EMBASE, CINAHL (1990–2012), Scopus, SCI (February 2013) and reference lists were searched. Inclusion criteria were primary intervention studies using skin care products in physiologically aged skin (lower age limit 50 years). Study and sample characteristics, interventions and outcomes were extracted. The methodological quality was assessed and a level of evidence was assigned. From 1535 screened articles 188 were read in full text. From these, 33 articles were included reporting results on treating dry skin conditions, and preventing incontinence‐associated dermatitis and superficial ulcerations. Most studies had lower levels of evidence of 3 or 4. Skin‐cleansing products containing syndets or amphoteric surfactants compared with standard soap and water washing improved skin dryness and demonstrated skin‐protecting effects. Moisturizers containing humectants consistently showed statistically significant improvements in skin dryness. Skin barrier products containing occlusives reduced the occurrence of skin injuries compared with standard or no treatment. Owing to methodological limitations the current evidence base for basic skin care in the aged is weak. Using low‐irritating cleansing products and humectant‐ or occlusive‐containing moisturizers seems to be the best strategy for maintaining the skin barrier function and integrity. We know little about the effects of cleansing regimens and about the benefits of moisturizers when compared with each other.     

Morphometry and epidermal fas expression of unexposed aged versus young skin

Background:

Identifying the molecular mechanisms of intrinsic aging is critical in developing modalities for reversal of cutaneous aging.

Objective:

The objective was to evaluate the expression of epidermal Fas, epidermal thickness, collagen, and elastic fibers degeneration in unexposed skin of aged individuals compared with young ones.

Materials and Methods:

Skin biopsies were taken from normal skin of the back of 22 old subjects (age range: 48-75 years) and 15 young subjects (age range: 18-28 years). Skin sections were stained with hematoxylin and eosin, Masson trichrome, orcein. Epidermal thickness was measured with image analyzer and scoring was done for collagen and elastic fiber degeneration. Fas immunostaining was done. Quantitative and qualitative data were compared statistically between the old and young subjects.

Results:

A statistically significant decreased epidermal thickness was found in old compared with young skin (P<0.05). A statistically significant number of patients showed decreased epidermal thickness, density, and fragmentation of both collagen and elastic fibers in old compared with young skin (P<0.001). Epidermal Fas expression was detected in 19 of 22 old subjects (86.4%) compared with 2 of 15 young subjects (13.3%) (P<0.001). There was no statistically significant correlation between age of old subjects and each of epidermal thickness, collagen, and elastic fiber degeneration.

Conclusion:

The decreased epidermal thickness and morphological alteration of collagen and elastic fibers are not correlated with aging and Fas-mediated apoptosis could be involved in thinning of the epidermis in unexposed aged skin.