Investigation of Age-Related Changes in the Skin Microbiota of Korean Women

Exploring the interplay between stress mediators and skin microbiota in shaping age-related hallmarks: A review

Psychological stress is a major contributing factor to several health problems (e.g., depression, cardiovascular disease). Around 35 % of the world's population suffers from it, including younger generations. Physiologically, stress manifests through neuroendocrine pathways (Hypothalamic-Pituitary-Adrenal (HPA) axis and Sympathetic-Adrenal-Medullary (SAM) system) which culminate in the production of stress mediators like cortisol, epinephrine and norepinephrine. Stress and its mediators have been associated to body aging, through molecular mechanisms such as telomere attrition, mitochondrial dysfunction, cellular senescence, chronic inflammation, and dysbiosis, among others. Regarding its impact in the skin, stress impacts its structural integrity and physiological function. Despite this review focusing on several hallmarks of aging, emphasis was placed on skin microbiota dysbiosis. In this line, several studies, comprising different age groups, demographic contexts and body sites, have reported skin microbiota alterations associated with aging, and some effects of stress mediators on skin microbiota have also been reviewed in this paper. From a different perspective, since it is not a "traditional" stress mediator, oxytocin, a cortisol antagonist, has been related to glucorticoids inhibition and to display positive effects on cellular aging. This hormone dysregulation has been associated to psychological issues such as depression, whereas its upregulation has been linked to positive social interaction.

Interaction between the microbiota and the skin barrier in aging skin: a comprehensive review

The interplay between the microbes and the skin barrier holds pivotal significance in skin health and aging. The skin and gut, both of which are critical immune and neuroendocrine system, harbor microbes that are kept in balance. Microbial shifts are seen with aging and may accelerate age-related skin changes. This comprehensive review investigates the intricate connection between microbe dynamics, skin barrier, and the aging process. The gut microbe plays essential roles in the human body, safeguarding the host, modulating metabolism, and shaping immunity. Aging can perturb the gut microbiome which in turn accentuates inflammaging by further promoting senescent cell accumulation and compromising the host's immune response. Skin microbiota diligently upholds the epidermal barrier, adeptly fending off pathogens. The aging skin encompasses alterations in the stratum corneum structure and lipid content, which negatively impact the skin's barrier function with decreased moisture retention and increased vulnerability to infection. Efficacious restoration of the skin barrier and dysbiosis with strategic integration of acidic cleansers, emollients with optimal lipid composition, antioxidants, and judicious photoprotection may be a proactive approach to aging. Furthermore, modulation of the gut-skin axis through probiotics, prebiotics, and postbiotics emerges as a promising avenue to enhance skin health as studies have substantiated their efficacy in enhancing hydration, reducing wrinkles, and fortifying barrier integrity. In summary, the intricate interplay between microbes and skin barrier function is intrinsically woven into the tapestry of aging. Sound understanding of these interactions, coupled with strategic interventions aimed at recalibrating the microbiota and barrier equilibrium, holds the potential to ameliorate skin aging. Further in-depth studies are necessary to better understand skin-aging and develop targeted strategies for successful aging.

Sacha inchi albumin delays skin-aging by alleviating inflammation, oxidative stress and regulating gut microbiota in d-galactose induced-aging mice

BACKGROUND

Sacha inchi albumin exhibits considerable functional activity with notable anti-inflammatory and antioxidation properties, which could delay skin aging. However, its underlying mechanisms for delaying skin aging have not been elucidated. The aim of the present study was to investigate the anti-skin-aging effect of sacha inchi albumin (SIA) in d-galactose induced-aging mice.

RESULTS

Sacha inchi albumin improved moisture content, collagen level, and the state of aged skin in rats. Sacha inchi albumin intervention markedly increased the skin antioxidant enzymatic activities including those of glutathione peroxidase, and catalase, but decreased the malondialdehyde content. It also regulated inflammation by reducing the level of tumor necrosis factor-α (TNF-α) and increasing the level of interleukin-6 (IL-6). Administration of SIA also increased the expression level of collagen I and III, increased the expression of tissue inhibitor of metalloprotease-1, and decreased the expression of metalloproteinases. Sacha inchi albumin can also activate the transforming growth factor-β (TGF-β)/Smad pathway. Meanwhile, 16S rRNA sequencing analysis revealed that SIA treatment altered the composition of microbiota, and increased the relative abundance of Lactobacillus, but decreased the relative abundance of Alloprevotella and Helicobacter, etc. Helicobacter was positively associated with malondialdehyde (MDA) content and was negatively related to IL-6.

CONCLUSION

Sacha inchi albumin exhibits excellent anti-skin-aging effect, which provide a new insight for the development of functional sacha inchi albumin. © 2023 Society of Chemical Industry.

Compositional Variations between Adult and Infant Skin Microbiome: An Update

Human skin and its commensal microbiome form the first layer of protection to the outside world. A dynamic microbial ecosystem of bacteria, fungi and viruses, with the potential to respond to external insult, the skin microbiome has been shown to evolve over the life course with an alteration in taxonomic composition responding to altered microenvironmental conditions on human skin. This work sought to investigate the taxonomic, diversity and functional differences between infant and adult leg skin microbiomes. A 16S rRNA gene-based metataxonomic analysis revealed significant differences between the infant and adult skin groups, highlighting differential microbiome profiles at both the genus and species level. Diversity analysis reveals differences in the overall community structure and associated differential predicted functional profiles between the infant and adult skin microbiome suggest differing metabolic processes are present between the groups. These data add to the available information on the dynamic nature of skin microbiome during the life course and highlight the predicted differential microbial metabolic process that exists on infant and adult skin, which may have an impact on the future design and use of cosmetic products that are produced to work in consort with the skin microbiome.

The impact of different diets and genders on fecal microbiota in Hanwoo cattle

Bovine fecal microbiota is important for host health and its composition can be affected by various factors, such as diet, age, species, breed, regions, and environments. The objective of this study was to evaluate the impact of diet and gender on fecal microbiota in Korean native Hanwoo cattle. The 16S rRNA gene amplicon sequencing of fecal microbiota was conducted from 44 Hanwoo cattle divided into four groups: (1) 11 heifers fed an oat hay plus total mixed ration (TMR) diet for breeding (HOTB), (2) 11 heifers fed an early fattening TMR diet (HEFT), (3) 11 steers fed the early fattening TMR diet (SEFT), and (4) 11 steers fed the late fattening TMR diet (SLFT). Firmicutes and Bacteroidota were the first and second most dominant phyla in all the samples, respectively. The Firmicutes/Bacteroidota (F/B) ratio associated with feed efficiency was significantly greater in the SLFT group than in the other groups. At the genus level, Romboutsia, Paeniclostridium, and Turicibacterwere the most abundant in the SLFT while Akkermansia, Bacteroides, and Monoglobus were the most abundant in the HOTB group. Although the same early fattening TMR diet was fed to Hanwoo heifers and steers, Marvinbryantia and Coprococcus were the most abundant in the HEFT group while Alistipes and Ruminococcus were the most abundant in the SEFT group. Shannon and Simpson diversity indices were significantly lower in the SLFT group than in the other groups. Distribution of fecal microbiota and functional genetic profiles were significantly different among the four treatment groups. The present study demonstrates that different diets and genders can affect fecal microbiota and the F/B ratio may be associated with feed efficiency in Hanwoo cattle. Our results may help develop strategies to improve gut health and productivity through manipulation of fecal microbiota using the appropriate diet considering Hanwoo cattle gender.

Effects of Air Pollution on Cellular Senescence and Skin Aging

The human skin is exposed daily to different environmental factors such as air pollutants and ultraviolet (UV) light. Air pollution is considered a harmful environmental risk to human skin and is known to promote aging and inflammation of this tissue, leading to the onset of skin disorders and to the appearance of wrinkles and pigmentation issues. Besides this, components of air pollution can interact synergistically with ultraviolet light and increase the impact of damage to the skin. However, little is known about the modulation of air pollution on cellular senescence in skin cells and how this can contribute to skin aging. In this review, we are summarizing the current state of knowledge about air pollution components, their involvement in the processes of cellular senescence and skin aging, as well as the current therapeutic and cosmetic interventions proposed to prevent or mitigate the effects of air pollution in the skin.

A Genome-Wide Association Study and Machine-Learning Algorithm Analysis on the Prediction of Facial Phenotypes by Genotypes in Korean Women

Purpose

Changes in facial appearance are affected by various intrinsic and extrinsic factors, which vary from person to person. Therefore, each person needs to determine their skin condition accurately to care for their skin accordingly. Recently, genetic identification by skin-related phenotypes has become possible using genome-wide association studies (GWAS) and machine-learning algorithms. However, because most GWAS have focused on populations with American or European skin pigmentation, large-scale GWAS are needed for Asian populations. This study aimed to evaluate the correlation of facial phenotypes with candidate single-nucleotide polymorphisms (SNPs) to predict phenotype from genotype using machine learning.

Materials and Methods

A total of 749 Korean women aged 30–50 years were enrolled in this study and evaluated for five facial phenotypes (melanin, gloss, hydration, wrinkle, and elasticity). To find highly related SNPs with each phenotype, GWAS analysis was used. In addition, phenotype prediction was performed using three machine-learning algorithms (linear, ridge, and linear support vector regressions) using five-fold cross-validation.

Results

Using GWAS analysis, we found 46 novel highly associated SNPs (p < 1×10⁻⁰⁵): 3, 20, 12, 6, and 5 SNPs for melanin, gloss, hydration, wrinkle, and elasticity, respectively. On comparing the performance of each model based on phenotypes using five-fold cross-validation, the ridge regression model showed the highest accuracy (r² = 0.6422–0.7266) in all skin traits. Therefore, the optimal solution for personal skin diagnosis using GWAS was with the ridge regression model.

Conclusion

The proposed facial phenotype prediction model in this study provided the optimal solution for accurately predicting the skin condition of an individual by identifying genotype information of target characteristics and machine-learning methods. This model has potential utility for the development of customized cosmetics.

Characterization of Distinct Microbiota Associated with Scalp Dermatitis in Patients with Atopic Dermatitis

Recent studies have focused on the role of skin microbiota in the pathogenesis of atopic dermatitis (AD). Among the various clinical phenotypes of AD, scalp dermatitis is a commonly observed clinical feature of AD. However, little is known about the pathogenesis of scalp dermatitis in AD. Hence, the aim of this study was to identify the distinct microbiota associated with scalp dermatitis in patients with AD. Using scalp swab samples from 10 patients with AD and 10 healthy controls, this study characterized the scalp microbiota in patients with AD via V3–V4 regions of the 16S rRNA gene sequencing for bacterial identification, and ITS2 gene sequencing for fungal identification. Among bacterial genera, Staphylococcus was the most abundant in AD than in healthy controls, whereas Cutibacterium was the most abundant species in the healthy controls. The most predominant scalp fungal microbiota was Malassezia both in AD and healthy controls, while a higher diversity of non-Malassezia fungi was observed in AD than in healthy controls. The study findings indicate the dysbiosis of scalp microbiota in AD and highlight the potential biomarker role of specific microbiota in AD on the scalp dermatitis.

Comparative analysis of human facial skin microbiome between topical sites compared to entire face

BACKGROUND

Skin is an essential outer barrier and supports the growth of commensal microorganisms that protects a host from the offense of foreign toxic organisms. With the rapid development of next-generation sequencing (NGS)-based applications, skin microbiome research for facial health care has reached industry growth, such as therapy and cosmetic product development. Despite the acceleration of skin microbiome research, experimental standardization protocol has not yet been established in the facial site and method of sampling.

OBJECTIVE

Thus, we aimed to investigate the differences in microbial composition at each facial site (cheek, mouth, forehead, and entire face) using comprehensive microbiome analysis.

METHODS

Twelve specimens from three men (four specimens per one person) were collected. The hypervariable regions (V3-V4) of the bacterial 16S rRNA gene were targeted for 16S amplicon library construction and classification of bacterial taxonomy. Skin microbial composition for all specimens was investigated, and the differences site-by-site in skin microbial composition were analyzed and evaluated by the various statistical tests.

RESULTS

We were able to validate the independent correlation between the skin microbiome composition and the facial sites. The cheek site showed the highest alpha-diversity in richness and evenness scores compared to the forehead and mouth. The cheek and mouth sites showed a positive correlation (R² value > 0.93) with the entire face, while the forehead sites were negatively correlated (R² value < 0.2). Given the relative abundance based on statistical correlation analysis, we estimated that the cheek site could be considered an optimal topical site to replace the entire face.

CONCLUSION

Our study suggests that skin microbiome profiling of four facial sites confirms that the cheek shows the most similar skin flora with the entire face. This study would be informative for preventing bias caused by sampling methods before researching and understanding skin cosmetics development or skin diseases.

Taxonomic profiling of skin microbiome and correlation with clinical skin parameters in healthy Koreans

The interest in skin microbiome differences by ethnicity, age, and gender is increasing. Compared to other ethnic groups, studies on the skin microbiome of Koreans remains insufficient; we investigated facial skin microbiome characteristics according to gender and age among Koreans. Fifty-one healthy participants were recruited, the facial skin characteristics of each donor were investigated, their skin bacterial DNA was isolated and metagenomic analysis was performed. The donors were divided into two groups for age and sex each to analyze their skin microbiomes. Moreover, we investigated the correlation between the skin microbiome and clinical characteristics. The alpha diversity of the skin microbiome was significantly higher in the elderly, and beta diversity was significantly different according to age. The comparative skin microbials showed that the genus Lawsonella was more abundant in the younger age group, and Enhydrobacter was predominant in the older age group. Staphylococcus and Corynebacterium were more abundant in males, while Lactobacillus was more abundant in females. Lawsonella had a negative correlation with skin moisture and brown spots. Staphylococcus and Corynebacterium both had negative correlations with the number of UV spots and positive correlations with transepidermal water loss (TEWL). Furthermore, Staphylococcus aureus had a negative correlation with skin moisture parameters.

Evaluation of the microbiome composition in particulate matter inside and outside of pig houses

Particulate matter (PM) produced in pig houses may contain microbes which can spread by airborne transmission, and PM and microbes in PM adversely affect human and animal health. To investigate the microbiome in PM from pig houses, nine PM samples were collected in summer 2020 inside and outside of pig houses located in Jangseong-gun, Jeollanam-do Province, Korea, comprising three PM samples from within a nursery pig house (I-NPH), three samples from within a finishing pig house (I-FPH), and three samples from outside of the pig houses (O-PH). Microbiomes were analyzed using 16S rRNA gene amplicon sequencing. Firmicutes was the most dominant phylum and accounted for 64.8%–97.5% of total sequences in all the samples, followed by Proteobacteria (1.4%–21.8%) and Bacteroidetes (0.3%–13.7%). In total, 31 genera were represented by > 0.3% of all sequences, and only Lactobacillus, Turicibacter, and Aerococcus differed significantly among the three PM sample types. All three genera were more abundant in the I-FPH samples than in the O-PH samples. Alpha diversity indices did not differ significantly among the three PM types, and a principal coordinate analysis suggested that overall microbial communities were similar across PM types. The concentration of PM did not significantly differ among the three PM types, and no significant correlation of PM concentration with the abundance of any potential pathogen was observed. The present study demonstrates that microbial composition in PM inside and outside of pig houses is similar, indicating that most microbe-containing PM inside pig houses leaks to the outside from where it, along with microbe-containing PM on the outside, may re-enter the pig houses. Our results may provide useful insights regarding strategies to mitigate potential risk associated with pig farming PM and pathogens in PM.

Cellular Senescence and Inflammaging in the Skin Microenvironment

Cellular senescence and aging result in a reduced ability to manage persistent types of inflammation. Thus, the chronic low-level inflammation associated with aging phenotype is called “inflammaging”. Inflammaging is not only related with age-associated chronic systemic diseases such as cardiovascular disease and diabetes, but also skin aging. As the largest organ of the body, skin is continuously exposed to external stressors such as UV radiation, air particulate matter, and human microbiome. In this review article, we present mechanisms for accumulation of senescence cells in different compartments of the skin based on cell types, and their association with skin resident immune cells to describe changes in cutaneous immunity during the aging process.

Dysbiosis and Enhanced Beta-Defensin Production in Hair Follicles of Patients with Lichen Planopilaris and Frontal Fibrosing Alopecia

Despite their distinct clinical manifestation, frontal fibrosing alopecia (FFA) and lichen planopilaris (LPP) display similar histopathologic features. Aberrant innate immune responses to endogenous or exogenous triggers have been discussed as factors that could drive inflammatory cascades and the collapse of the stem cell niche. In this exploratory study, we investigate the bacterial composition of scalp skin and plucked hair follicles (HF) of patients with FFA, LPP and alopecia areata circumscripta (AAc), as well as healthy individuals, in relation to cellular infiltrates and the expression of defense mediators. The most abundant genus in lesional and non-lesional HFs of LPP and FFA patients was Staphylococcus, while Lawsonella dominated in healthy individuals and in AAc patients. We observed statistically significant differences in the ratio of Firmicutes to Actinobacteria between healthy scalp, lesional, and non-lesional sites of FFA and LPP patients. This marked dysbiosis in FFA and LPP in compartments close to the bulge was associated with increased HβD1 and HβD2 expression along the HFs from lesional sites, while IL-17A was increased in lesional HF from AAc patients. The data encourage further studies on how exogenous factors and molecular interactions across the HF epithelium could contribute to disease onset and propagation.