Age-related differences in the functional properties of lips compared with skin

Human lip vermilion: Physiology and age-related changes

BACKGROUND

The human lip vermilion, also known as the red lip, is important to the quality of life and has long attracted the attention of cosmetic researchers. However, there is limited existing literature on the physiological characteristics and age-related alterations in the human vermilion.

OBJECTIVE

We aim to provide an overview of the physiological characteristics and age-related alterations in the human vermilion.

METHODS

This article is a result of previous research. We conducted a literature search using various academic databases such as Google Scholar, Web of Science, and PubMed. Our findings provided a comprehensive understanding of the physiological characteristics and age-related changes of the human lip vermilion.

RESULTS

The human lip vermilion has a unique structure and physiological characteristics, and during the aging process, a few changes may occur in the human lip vermilion.

CONCLUSION

Understanding the human lip vermilion's physiological characteristics and age-related changes can provide key information for the future innovation of lip vermilion care products. Further investigations are necessary to reach a consensus on the physiological characteristics and age-related alterations in the human vermilion.

Image-based investigation of lip aging features in a large number of Korean women

BACKGROUND

The lips play a significant role in shaping facial aesthetics. Due to the distinct attributes of lips in contrast to other facial skin, a unique approach is imperative for managing lip aging. We analyzed lip characteristics (morphology, wrinkles, and color) to investigate visual changes and distinctive attributes of aging lips.

METHODS

By utilizing image data processing methods, including facial landmark detection, pattern recognition, and color quantification, we extracted 11 lip characteristic indices (four morphological indices, four wrinkle indices, and three color indices) from high-resolution images of 1000 Korean women aged 20-69. Correlation tests were conducted to assess the relationship between lip characteristic indices and age, and also between lip morphological and wrinkle indices.

RESULTS

Lip height significantly decreased, while lip width and lip ratio (lip width divided by the sum of the upper and lower lip height) significantly increased with aging. Lip wrinkles significantly increased with aging, whereas lip colors (redness and yellowness) decreased. The lip wrinkle indices, which are segmented for the first time in this study, exhibited significant correlations with lip width, and three of them additionally were correlated with lip ratio (p < 0.05). The results imply such morphological changes can be associated with wrinkle formation of human lips.

CONCLUSION

The indices suggested in this study can be used for assessing lip aging characteristics, and the study results can contribute to deeper understanding of lip aging.

Novel assessment of lip redness and microcirculation using optical coherence tomography after dermal filler injection

OBJECTIVES

Lip filler injections are one of the most popular procedures in esthetic dermatology. In this study, we used three-dimensional colorimetric photography to assess lip color and optical coherence tomography-angiography (OCT-A), a noninvasive alternative to histopathology, to evaluate microcirculation after hyaluronic acid (HA) injection. The pain of the injection procedure was also assessed.

METHODS

An average of 0.85cc of the total volume of HA with lidocaine was injected into the upper and lower lip of eighteen young (<30yo) and nine postmenopausal healthy women. OCT-A, two-dimensional, and three-dimensional images were acquired immediately before (visit 1) and 15 days after injection (visit 2). Custom-made software was used to analyze the imaging data to detect vessel morphology and redness changes. The Wong-Baker FACES pain rating scale (0-10) was used to score the subject procedural pain.

RESULTS

For young and old subjects, three-dimensional lip volume was greater than the injected volume. OCT-A images of the lips showed higher vessel density and thickness, reaching statistical significance in the younger cohort. The overall trend of increased redness assessed by three-dimensional colorimetric imaging and increased vascularity evaluated by OCT-A imaging were similar. However, the correlation was not statistically significant for standard two-dimensional digital photography. The average pain score after the first needle insertion and overall procedure were 2.9 and 3.5, respectively.

CONCLUSIONS

The results suggest an increased microvasculature network observed in OCT-A images in young females. The increased blood vessel density and thickness observed by OCT-A after HA lip filler injection is associated with increased lip redness and volume as assessed by colorimetric three-dimensional photography; however, more research is needed to confirm these findings. This study presents OCT-A as a novel noninvasive tool to investigate changes in lip microvascularity after HA filler injection and indicates that HA filler procedures may affect lip vascularity.

Development of a lip vermilion epithelium reconstruction model using keratinocytes from skin and oral mucosa

Lip vermilion is unique and can be distinguished from the adjacent skin and oral mucosa. However, because of the lack of appropriate evaluation tools, skin and/or oral mucosa substitutes such as in vitro vermilion epithelial models have been used for lip product testing. We aimed to develop and characterize a lip vermilion epithelium reconstruction model (LVERM) using skin and oral keratinocytes. LVERM was manufactured by co-culturing primary skin and oral keratinocytes, using a device that allowed the separation of cell seeding, and created an intercalated cell-free zone, referred to as the vermilion part. After removing the device, LVERM construction was completed in 8 days, in a submerged condition. Subsequently, they were placed in an air-liquid interface for 7 days. To determine the epithelial characteristics of LVERM, keratin 2e (KRT2) and small proline-rich protein 3 (SPRR3) expression patterns were examined. The in vivo expression profiles of KRT2 and SPRR3 genes in vermilion were also examined. We found that a continuous multi-layered epithelium was generated in the LVERM that exhibited ortho- and para-keratinization in the skin and oral mucosa parts, respectively. Although an intermediate keratinization pattern was observed in the vermilion part, KRT2 and SPRR3 were co-expressed in the suprabasal layer, consistent with the expression pattern of a single vermilion epithelial model. Clustering analysis revealed that KRT2 and SPRR3 gene expression in vermilion was location-dependent within the sample. Therefore, LVERM can be used as an evaluation tool for lip products and has great importance in innovative approaches for cosmetic testing.

Lip color measurement: A new hyperspectral imaging device

INTRODUCTION

The lips are of significant interest among the facial features for self-perception and social interactions. Such perceptions could rely in part upon the contrast in color between the lips and the surrounding skin. In contrast to skin color, lip color ethnic diversity measurement provides a challenge and is less documented in the literature, most likely due primarily to challenges in measurement based upon the lip characteristics of size and contour. Accurate measurement and reproduction of lip color are essential to build strong cross-sectional knowledge about lip color.

OBJECTIVE

This preliminary experiment of a large-scale project on lip and skin color was designed to assess accuracy in lip color measurement and recommend instruments and protocols for good measurement practice.

METHODS

The study involved 19 healthy French Caucasian women. Their inferior and superior natural lip color was measured twice with three devices in order to extract the standard colorimetric parameters of lightness (L*), chroma (C*), and hue (h): the VISIA-CR® (high-resolution digital camera, Canfield Scientific Inc.); the spectrophotometer VS3200 (45°:0° spectrophotometer, MetaVue™ VS3200, X-Rite Inc.); and the SpectraFace® (new hyperspectral imaging system, Newtone Technologies). The intercomparison and color distribution between the different instruments and the measurement repeatability of each one were assessed.

RESULTS

Our results showed a reliable and equivalent repeatability for the three tested instruments. Moreover, the three tools led to the same conclusion regarding lip color heterogeneity (lighter, redder, less yellow and more saturated inferior lip versus superior lip). Agreement between the SpectraFace® and the spectrophotometer measurements was higher, and the SpectraFace® allowed to identify three separated lip color typologies.

CONCLUSION

In conclusion, the combination of imaging technology and hyperspectral measurement makes the SpectraFace® a useful tool to investigate lip color characterization and establish a large-scale cross-sectional knowledge study about lip color.

Feasibility of smartphone colorimetry of the face as an anaemia screening tool for infants and young children in Ghana

BACKGROUND

Anaemia affects approximately a quarter of the global population. When anaemia occurs during childhood, it can increase susceptibility to infectious diseases and impair cognitive development. This research uses smartphone-based colorimetry to develop a non-invasive technique for screening for anaemia in a previously understudied population of infants and young children in Ghana.

METHODS

We propose a colorimetric algorithm for screening for anaemia which uses a novel combination of three regions of interest: the lower eyelid (palpebral conjunctiva), the sclera, and the mucosal membrane adjacent to the lower lip. These regions are chosen to have minimal skin pigmentation occluding the blood chromaticity. As part of the algorithm development, different methods were compared for (1) accounting for varying ambient lighting, and (2) choosing a chromaticity metric for each region of interest. In comparison to some prior work, no specialist hardware (such as a colour reference card) is required for image acquisition.

RESULTS

Sixty-two patients under 4 years of age were recruited as a convenience clinical sample in Korle Bu Teaching Hospital, Ghana. Forty-three of these had quality images for all regions of interest. Using a naïve Bayes classifier, this method was capable of screening for anaemia (<11.0g/dL haemoglobin concentration) vs healthy blood haemoglobin concentration (≥11.0g/dL) with a sensitivity of 92.9% (95% CI 66.1% to 99.8%), a specificity of 89.7% (72.7% to 97.8%) when acting on unseen data, using only an affordable smartphone and no additional hardware.

CONCLUSION

These results add to the body of evidence suggesting that smartphone colorimetry is likely to be a useful tool for making anaemia screening more widely available. However, there remains no consensus on the optimal method for image preprocessing or feature extraction, especially across diverse patient populations.

Non-ablative laser treatment improves lip volume, texture, and color

Lips undergo several changes with age, decreased volume, elasticity, turgor, and collagen content. Q-switched Nd:YAG laser are known to increase the production of procollagen and elastin and can promote the generation of collagen, which visibly improves facial imperfections. We aimed to determine the efficacy of a 1064 nm Q-switched Nd:YAG fractional laser on improving lip definition, color, and volume. 32 female patients were treated every 2-3 weeks for a total of 3-5 treatments. Improvement was measured in a follow-up visit a month after the final treatment (29.9 ± 1.4 days) by patients' self-satisfaction questionnaire and physicians blinded evaluations (Likert scale). Patients achieved meaningful aesthetic improvement in in lip color (94% of patients), volume (72%), texture (91%), and overall lip appearance (82%). Furthermore, 91% were satisfied with treatment results and 100% from the overall experience. There were no associated side effects, and the associated pain level (on a 0-10 scale) was rated as 0 in 84% of individuals and 16% as 1. Therefore, laser treatment using a 1064 nm Q-switched Nd:YAG fractional laser on lips is a safe, noninvasive treatment that increases the color and volume of lips, with results that are maintained for at least one month following treatments.

Relationship between lip skin biophysical and biochemical characteristics with corneocyte unevenness ratio as a new parameter to assess the severity of lip scaling

Objective

Lip skin dryness and chapping are major concerns related to lip skin care in many populations. The distinctive features of lip skin, such as the low water‐holding capacity and weak skin barrier, are strongly associated with these problems; however, few studies have examined lip skin characteristics and the mechanisms underlying these issues. This study was conducted to identify the biophysical properties of dry lip skin and molecular targets affecting lip skin physiology.

Methods

Skin hydration, transepidermal water loss and lip skin scaling were evaluated in 40 female subjects. Skin scaling was assessed as a percentage area divided into five categories (G0, G1, G2, G3 and G4) according to the thickness level of tape‐stripped corneocytes. The activities and amounts of proteases, cathepsin D and bleomycin hydrolase were measured as markers for the desquamation process and skin hydration, respectively.

Results

Skin hydration showed a significantly positive correlation with the percentage area of evenly thin corneocytes (G0) and negative correlations with the percentage areas of slightly thick to severely thick corneocytes (G1‐G4). The corneocyte unevenness ratio (CUR) was calculated by dividing the sum of the G1, G2, G3 and G4 values with the G0 value. The CUR was significantly negatively correlated with skin hydration, suggesting that CUR is a new parameter representing the severity of lip scaling. Subjects with lower hydration and higher CUR had higher bleomycin hydrolase activity and lower cathepsin D activity, respectively, than subjects with higher hydration and lower CUR.

Conclusion

Our study revealed a correlation between lip skin hydration and severity of lip scaling and verified the association of protease activity with the hydration and chapping state of lip skin. These observations provide a basis for further studies of the persistent problem of lip skin dryness and chapping.

Age-related changes in the vasculature of the dermis of the upper lip vermilion

Lip redness is unique to humans and creates an important facial impression, but this redness decreases with age. Here, using histological and immunohistological staining of human upper lip vermilion from donors of different ages, we investigated blood vessels in the upper lip dermis and age-dependent histological changes. We found that both total vessel area in the dermis and vessel number in the upper dermis decreased with aging. Moreover, vessel number in the upper dermis correlated positively with development of rete ridges, which flattened with age, despite no significant change in the thickness of the stratified squamous epithelium. These findings suggest that age-related reductions in lip redness result from a decrease of blood vessels, which in turn leads to a flattening of the epithelium caused by the loss of rete ridges. This is the first study to histologically demonstrate age-related reductions in blood vessels in the lip. Our results provide an opportunity for enhancing blood flow/vascularization to improve the aesthetic appearance of the lips in the elderly.

Comprehensive histological investigation of age-related changes in dermal extracellular matrix and muscle fibers in the upper lip vermilion

OBJECTIVE

Few histological studies have directly examined age-related changes within the lips, although non-invasive investigations of such changes are increasing. Therefore, this study aimed to provide histological and molecular data on age-dependent alterations in the vermilion.

METHODS

Upper vermilion specimens from 15 female Caucasian cadavers (age range, 27-78 years) were investigated histologically or immunohistochemically.

RESULTS

Histologically, age-dependent decreases in areas occupied by hyaluronan and collagenous fibres in the dermis of upper vermilion were demonstrated. Elastic fibre content varied widely between individuals. The area occupied by muscle fibres in the orbicularis oris muscle region within the vermilion also correlated negatively with age. Immunohistochemically, signals of four proteins were attenuated in vermilion from older individuals compared with young individuals: procollagen type I, hyaluronan synthase (HAS)1, myosin heavy chain (MYH)2 (a component of fast-twitch oxidative muscle fibres) and MYH7 (a component of slow-twitch muscle fibres). In contrast, signals of cell migration inducing hyaluronidase 1 (CEMIP) were intensified in vermilion from older individuals. No marked differences between young and older individuals were seen in procollagen type III, HAS2, HAS3, hyaluronidase (HYAL)1, HYAL2, MYH1 or MYH4.

CONCLUSION

Age-dependent decreases of hyaluronan in the dermis of vermilion were prominent, possibly due to both the decrease in synthesis (HAS1) and the increase in degradation (CEMIP). Furthermore, age-dependent decreases in collagenous fibres and two types of muscle fibre in the vermilion were also identified histologically. Type I collagen, MYH2 and MYH7 appear to represent the molecules responsible for these respective decrements.

Characterization and validation of an in vivo confocal Raman spectroscopy led tri-method approach in the evaluation of the lip barrier

Background/Aim

It was the aim to establish and validate in vivo confocal Raman spectroscopy for characterization of the lip barrier in conjunction with transepidermal water loss (TEWL) and skin capacitance assessments. For the first time in vivo, barrier‐relevant components of the lip (derived, natural moisturizing factors (NMFs) and ceramides are described.

Methods

In 32 healthy volunteers, a dental tongue fixation device was inserted to prevent both voluntary and involuntary lip moisturization during measurements. Seventeen individual parameters relating to water, ceramide, and NMF content were assessed via Raman spectroscopy. Additionally, corneometry and TEWL were measured. To give a guidance for the required volunteer group size of future lip barrier studies for all test parameters, coefficients of variation (CV) were calculated and plots showing the required sample size for a given percentage treatment effect.

Results

Raman spectroscopy assessed parameters on the lower lip comprehensively characterized the state of the lip barrier. Parameter variability was sufficiently low to corroborate changes in most parameters using relatively small study populations.

Conclusions

Lip skin is comparatively well hydrated. Biophysical measurement of the lip barrier function is a challenge, as unconscious licking of the lower lip has to be prevented. In vivo confocal Raman spectroscopy provides insightful parameters for the characterization of the lip barrier and sufficiently low inter‐individual variability to assess relatively small parameter changes employing relatively few study subjects. Differences at the molecular level and at a high spatial resolution are detectable, and these insights might provide a breakthrough in the evaluation of lip barrier function and developing solutions for lip care.

The effect of aging in primary human dermal fibroblasts

Skin aging is a complex process, and alterations in human skin due to aging have distinct characteristic as compared to other organs. The aging of dermal cells and the biological mechanisms involved in this process are key areas to understand skin aging. A large number of biological mechanisms, such as decreasing of protein synthesis of extracellular matrix or increasing of degradation, are known to be altered through skin aging. However, environmental influence can accelerate this characteristic phenotype. In this study, we analyzed primary human dermal fibroblasts in three different in-vitro aging models—UVB irradiation and accelerated proliferation of human dermal fibroblasts from young donors as well as from elderly donors—for the gene expression of COL1A1, COL1A2, COL3A1, COL4A1, COL7A1, MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP12, MMP13, MMP14, TIMP1, TIMP2, TIMP3, TIMP4, IL1B, IL1A, IL6, IL8, IL10, PTGS2, TP53, CASP3, LMNA, SIRT1. We compared the gene expression levels with young control. Furthermore, the behavior of skin fibroblasts was also evaluated using cell growth rate. The findings reveal that the gene expression levels in skin fibroblasts was altered in the process of aging in all three in-vitro aging models, and the cell growth rate was reduced, suggesting that these methods can be employed to understand skin aging mechanisms as well as drug discovery screening method.

Understanding rates of genital-anal injury: Role of skin color and skin biomechanics

PURPOSE

A series of studies suggest that non-Hispanic White women have significantly more injuries than non-Hispanic Black women after sexual assault and consensual sexual intercourse. One explanation for this difference is that the degree of skin protection may vary as skin mechanics and skin pigmentation vary. The aim of the study was to determine the association among genital-anal injury, skin color, skin viscoelasticity and skin hydration in women following consensual sexual intercourse when controlling for age, smoking history, body mass index (BMI), sun exposure, and health status.

PROCEDURES

We employed a prospective cohort study design to enroll women 21 years of age or older at two study sites. They underwent two data collection sessions, baseline and follow-up after consensual sexual intercourse. Baseline genital-anal injury identification occurred with a standard forensic examination (direct visualization, nuclear staining with toluidine blue contrast, and colposcopy examination) and measurements of other variables (skin color, skin viscoelasticity, skin hydration, age, smoking history, body mass index [BMI], sun exposure, and health status). Participants were then asked to have consensual sexual intercourse with a male partner of their choice and to return for a second forensic examination for injury detection. Genital-anal injury was regressed on skin color, skin viscoelasticity, skin hydration, age, smoking history, BMI, sun exposure, and health status.

FINDINGS

We enrolled 341 participants, 88 non-Hispanic White (25.8%), 54 non-Hispanic Black (15.8%), 190 Hispanic/Latina (55.7), and 9 Other Identities (2.6%). At baseline the genital-anal injury prevalence was 57.77% and at follow-up after consensual sexual intercourse, injury prevalence was 72.73%. External genital injury prevalence was associated with increased L* (lightness) values (Adjusted Odds Ratio [AOR] = 1.98, 95% Confidence Interval [CI] = 1.03, 4.04) and decreased skin elasticity (AOR = 0.96, 95% CI = 0.93, 0.99) at baseline. Increased skin hydration was associated with a significantly higher frequency of external, internal, anal, and total genital-anal injuries (Adjusted Rate Ratio [ARR] > 1.27) at follow-up. Also at the follow-up examination, Hispanic/Latina participants had significantly lower external genital and total genital-anal injury prevalence and frequency as compared to non-Hispanic White participants (AOR < 0.40).

CONCLUSIONS

Our findings provide qualified support for the importance of skin color during the forensic examination. Women with lighter skin tones may have skin that is more easily injured than women with darker tones. In contrast, external genital injuries may be more easily identified in women with light as compared to dark skin, a situation that is important in both the health care and criminal justice systems. Additionally, women with decreased viscoelasticity and increased hydration may be more easily injured. These findings support the need to develop forensic procedures that are effective in people across the range of skin colors and to interpret forensic findings considering the innate properties of the skin.

Deposition of plant lipids after single application of a lip care product determined by confocal raman spectroscopy, corneometry and transepidermal water-loss

OBJECTIVE

Lip treatment products often incorporate oils and waxes in their formulations, and a desired outcome of their use is to prevent lip dryness and roughness as well as help to repair this condition. The objective of this study was to combine confocal Raman spectroscopy with skin capacitance (corneometry) and transepidermal water loss (closed chamber Aquaflux system) measurements, in the evaluation of the degree of moisturization and lip skin penetration of a fruit wax (Rhus vernicula peel cera) and natural oil-based (Cocos nucifera fruit oil and Olea europea oil) lip care product, following a single application.

METHODS

The study was conducted on a total of 15 healthy female volunteers. Instrumental measurements were performed before and 30 min, 2 h and 6 h after a single application of the product.

RESULTS

Lip skin barrier function as well as lip hydration were significantly improved and penetration of olive oil was maintained for at least 6 h post product application. The deposition of the three component lipids (berry fruit wax, coconut oil and olive oil) into the stratum corneum after a single application of the lip care product was maintained and data significant for 2-6 h post product application. Lipid deposition was regarded as a positive long-lasting skin care (depot-) effect combined with a profound hydrating effect for about 6 h.

CONCLUSION

The tri-method approach taken in this study is deemed relevant and valid for measuring lip hydration offering a complimentary assessment of the barrier function of lip skin and interactive effects of cosmetic ingredients.

Age-related changes in lip morphological and physiological characteristics in Korean women

OBJECTIVE

Age-related changes in lip morphological and physiological characteristics are key indices for estimating age based on facial features, as reported in many studies. Yet, a majority of studies have focused on Caucasian individuals, with few studies characterizing these changes in Asian female populations. Therefore, the aim of this study was to investigate lip morphological and physiological characteristics in a cohort of Korean women.

METHODS

A total of 114 volunteers participated in the study. Linear distances (length of philtrum, length of lip, width of lip, and lengths of lower and upper oral commissures), angle of the upper lip, 3D lip heights, and wrinkles were calculated and averaged for each age-group. We also measured lip color, hydration, trans-epidermal water loss (TEWL), and blood flow. Statistical analyses were performed using SPSS version 20.0 (significance level P < 0.05).

RESULTS

Length of the philtrum and lip width significantly increased with age while upper and lower lip lengths and length of the lower oral commissure significantly decreased with age. The angle of the upper lip tended to decrease with age, but this finding was no significance. Three-dimensional height of the upper lip, wrinkles, and TEWL also decreased with age while hydration increased with age. Finally, redness of the upper and lower lips as well as blood flow significantly decreased with age.

CONCLUSION

Lips tended to shorten in length and widen with age, resulting in a thinner and longer appearance. With regard to physiological parameters, there were important age-related changes in hydration and lip color.