Study On The Risks Of Facial Skin Aging Of Chinese And The Effects Of Cigarette Smoking Extract And Nicotine On Skin Cell Senescence

Skin aging is the chronic process that many factors can be involved in this skinchange. The presence of wrinkles and pigmentary changes, such as solar lentigo, aswell as mottled pigmentation on the face or other exposed areas of the body are themajor manifestations of skin aging. The aging process of the skin can be divided intoextrinsic aging and intrinsic aging. It is well documented that severe wrinkles andpigmentary changes of the exposed skin indicate substantial damage due to UVradiation. Intrinsic aging process is often described as natural aging which is affetedby a lot of physical factors, such as inherit factors, endocrine factors, etc. It isbelieved that this process is very complicated and many factors can be involved in thiscourse.Although the process of skin aging will take place to everybody, the clinicalpresences are different. Many investigators believe, based on experiences, that theprincipal manifestation of photodamage in Asians is pigmentary change rather thanwrinkling. However, to our knowledge, no well-designed study has investigated thecharacteristics of cutaneous photodamage in Asians. Because of the great differencebetween two ethnic, Mongoloids and Caucasians, many photographic scales for theassessment of photodamage in white subject may be not be applied to evaluate thechanges of the skin in Mongoloids. So we applied the system of photographic scalescreated by Jin Hochung, which can well evaluate Korean facial manifestations of skinaging, to assess the changes of Chinese facial skin. Furthermore, we also investigatedthe risks which may affect the skin aging of Chinese.Acoording to the previous epidemiology study, we studied the effects of cigarette smoking extract(CSE) and nicotine on skin cell senescence in vitro.Thefollowing study is divided into two parts: one is to study the effects of CSE andnicotine on cell proliferation and the growth of primary culture fibroblasts of skin; theother is to determine the effects of Cigarette Smoke Extract on the collagen sythesisand the mechanism of oxidative damage in the process of skin cell senescence byCSE.Objective:1. To investigate the risk factors that can affect the process of skin aging in Chinese;to assess the severity of wrinkles and dyspigmentation of facial skin aging inChinese.2. To study the effects of CSE and nicotine on cell proliferation and the growth of theprimary cultured skin fibroblasts.3. To investigate the effects of CSE on the collagen synthesis and the mechanism ofoxidative damage in the process of skin cell senescence induced by CSE.Methods:1.195 subjects were interviewed to learn the relationship between the skin aging andmany risk factors including sun exposure, smoking, sex, etc. by answering thequestionnaire and taking the photos of the face on the left side. After comparing thephotographes of the subjects with the album of standard photo, we can gradewrinkles and dyspigmentation seperatly of the facial skin in every person by 2separate scales of Jin Hochung.2. The potential of cell proliferation at different concentrations of CSE and nicotinewere detected by the tetrazolium dye colorimetric test (MTT test). Themorphological changes of fibroblasts treated by CSE for 24 hours were observed.The growth curves of fibroblasts treated by CSE and nicotine were drawn with MTTmethod. The positive cell rates of senescence-associatedβ-galactosidase offibroblasts treated for 5 passages by CSE were detected and analyzed. The growthcurves of fibroblasts treated by low concentration of CSE for 5 passages were drawnwith MTT method. Flow cytometry was used to estimate cell cycle phases after the fibroblasts were treated with different concentrations of CSE and the cells wereaffected at different time.3. The amount of cellular ROS, and activities of cellular SOD were determined bybiochemical methods; The production of collagen was deteced by photometricdetermination and the mRNA expression for typeâ… procollagen was detected byRT-PCR method.Research results found:1. Wrinkle is the major feature of photoaging in Chinese, as are pigmentary changes;smoking, sun exposure, and female sex are independent risk factors for wrinkles.2. The fibroblasts displayed morphological changes after 24 hours' effect of CSE. Thegrowth of fibroblasts was apparently slowed down by CSE, but the proliferation andthe growth of skin fibroblasts can be stimulated by the low concentration of nicotine.Theβ-galactosidase staining was detected in fibroblasts cultured with CSE for 5passages. The growth of fibroblasts treated by CSE for 5 passages was apparentlydelayed. Flow cytometry analysis demonstrated that CSE decreased the cells in Sphase and increased the cells in G₁ and G₂ phases.3. CSE can inhibit the synthesis of collagen. Oxidative damage may be one of themechanisms that contribute to the process of the skin aging.Conclusion:Wrinkle is the major feature of skin aging in Chinese, as are pigmentary changes;smoking, sun exposure, and female sex are independent risk factors for wrinkles.CSE can inhibit the proliferation and the growth of the primary cultured skinfibroblast.CSE can accelerate the process of skin aging. Futhermore, CSE can inhibitthe synthesis of collagen, and oxidative damage may be one of the mechanisms thatcontribute to the process of the skin aging.