The Evaluation Of Sensitive Skin And The Study Of Gene Polymorphism For TRPV1

Background Sensitive skin(SS) refers to the hyper-intolerance of skin, abnormal sensations(pruritc, burning, stinging, tightness and pain) appear after exposed to cosmetic or certain conditions, occasionally with erythema, furfuration, et al. The frequency of sensitive skin is 13% in our country(8.62% in men and 15.93% in women), but about 50% in Japan and occident. The possible pathogenesis was the decreased barrier function of skin, the increased signal input of sensory nerve, inflammation or vascular reaction and genetic factor. At present, the decreased barrier function has been studies relatively comprehensive but few about the heighted neural and vascular reaction. The most common position of sensitive skin was face, then is scalp, neck, hand and trunk, et al. Various kind of environment factors(the variation of temperature, pollution, air-condition, water), climatic factors(cold, heat, sun, wind, dryness or moist air), cosmetic, mental factors(stress, emotion) and physiological factor(menstrual cycle) can induce or aggravate sensitive skin. The methods for the evaluation of sensitive skin include subjective evaluation, half-subjective evaluation and objective evaluation. The subjective evaluation has two forms of question and questionnaire. The half-evaluation refers to chemical probe test. And the objective evaluation is the measurement of biophysics parameters of skin by noninvasive instruments. The transient receptor potential vanilloid 1(TRPV1) on keratinocyte and sensory nerve has close relation with the occurrence of sensitive skin. The stimulated TRPV1 by capsaicin can release neuropeptide to induce neurogenic inflammation. Previous studies demonstrated the human TRPV1 has single nucleotide polymorphisms(SNPs). Our study select 4 TRPV1 gene SNPs into study, which include RS222747, RS224534, RS4790523 and RS8065080.Objective Evaluate the neural and vascular hyper-reactivity of sensitive skin and explore the characteristic of gene polymorphism of TRPV1; Investigate the epidemiological difference between sensitive facial skin and sensitive scalp.Methods The first session: The evaluation of neural and vascular hyper-reactivity of sensitive skin and the study of SNPs of TRPV1. 183 healthy women completed the test. The whole process include two stages. In selection phase, 183 self-perceived sensitive skin subjects were screened by lactic acid stinging test(LAST). Venous blood(5ml) were collected for standby. In the formal test phase, the baseline value of blood flow(BL) and current perception threshold(CPT) was measured by noninvasive instruments firstly. Then, the 0.001% capsaicin was applied to the nasolabial fold for 5min. After the capsaicin test(CAT), the BF(immediately after the CAT) and the CPT(1h later after the CAT) were measured again. The collected blood samples were used for the analysis for the SNPs of TRPV1. The second session: The survey of difference between sensitive scalp and sensitive facial skin in Shanghai. Total 337 healthy women completed the questionnaire. According to the different influence factors in specific position of face and scalp and related articles, two sets of questionnaire were designed: sensitive facial skin questionnaire and sensitive scallp questionnaire. Each questionnaire was consist of three parts:(1) self assessment of facial skin or scalp whether sensitive or not;(2) If the answer is sure, the instruction of general Labeled Magnitude scale(g LMS) was explained to the informants, then let them to assess the total level of sensitivity of themselves. 0 means “no sensitive” and 10 means “the strongest sensitive imagiable”;(3) Evaluating the frequency of various influence factors and aymptoms of sensitive facial skin and sensitive scalp respectively. All subjects completed two sets of questionnaires.Results The first session: The positive-group had lower baseline value of CPT at 5Hz(p(27)0.01) and 250Hz(p(27)0.01) compared with the negative-group, but no difference in baseline value of BF(p(29)0.05). After the CAT, significant variation of CPT at 5Hz(p(27)0.01) and 250Hz(p(27)0.05) as well as the BF(p(27)0.01) were found in positive-group but not in negative-group. The genotype frequencies of AG/GG in RS224534 and AC/CC in RS4790523 in the positive-group were higher than the negative-group. The second session: Total 337 individuals completed the survey. The incidence of SPSP was slightly higher than SPSS. There was no difference(p(29)0.05)of the incidence for each age group. The predominant triggering factor of SPSS was the variation of temperature(78.16%), and the most common manifestation was tightness(73.56%). As for SPSP, its uppermost triggering factor was dryness(60.50%) and the most common sensation was itching(79.83%). The self-assessment of SPSS was higher(p(27)0.05) than that of SPSP. But for the population with both SPSS and SPSP, no difference was found between them in self-assessment(p>0.05). There was no correlation between age and the intensity of SPSS and SPSP.Conclusion The sensitive subjects were prone to be stimulated by capsaicin to trigger neural and vascular hyperreactivity. The genetic variation of TRPV1 demonstrate that TRPV1 play an important role in the pathogenesis of sensitive skin. Our study suggest that sensory irritation inhibitors and anti-inflammatory compounds should be considered to be added in cosmetics to reduce the heighted neural and vascular reaction of sensitive skin. Except for the sensitive facial skin, sensitive scalp has been got more and more attention. Because of the different anatomical sites and physiological feature, the sensitivity in different position were different, which mainly include frequency, manifestation and triggering factors. Three different methods were involved in our study. Different methods are aimed at different purposes. Sensitive questionnaires always used for epidemiological survey. Then the chemical probe test and noninvasive detection are mainly used to screen SS and measure the biophysics parameters.