Probiotics as a targeted intervention in anti-ageing: a review

CONTEXT

The age-induced disruption of gut flora, termed gut dysbiosis, is intimately tied to compromised immune function, augmented oxidative stress and a spectrum of age-linked disorders.

OBJECTIVE

This review examines the fundamental mechanisms employed by probiotic strains to modulate gut microbiota composition and metabolic profiles, mitigate cognitive decline via the gut-brain axis (GBA), modulate gene transcription and alleviate inflammatory responses and oxidative stress.

CONCLUSION

We elucidate the capacity of probiotics as a precision intervention to restore gut microbiome homeostasis and alleviate age-related conditions, thereby offering a theoretical framework for probiotics to decelerate ageing, manage age-related diseases, and elevate quality of life.

The influence of lifestyle and environmental factors on host resilience through a homeostatic skin microbiota: An EAACI Task Force Report

Human skin is colonized with skin microbiota that includes commensal bacteria, fungi, arthropods, archaea and viruses. The composition of the microbiota varies at different anatomical locations according to changes in body temperature, pH, humidity/hydration or sebum content. A homeostatic skin microbiota is crucial to maintain epithelial barrier functions, to protect from invading pathogens and to interact with the immune system. Therefore, maintaining homeostasis holds promise to be an achievable goal for microbiome-directed treatment strategies as well as a prophylactic strategy to prevent the development of skin diseases, as dysbiosis or disruption of homeostatic skin microbiota is associated with skin inflammation. A healthy skin microbiome is likely modulated by genetic as well as environmental and lifestyle factors. In this review, we aim to provide a complete overview of the lifestyle and environmental factors that can contribute to maintaining the skin microbiome healthy. Awareness of these factors could be the basis for a prophylactic strategy to prevent the development of skin diseases or to be used as a therapeutic approach.

The Role of Probiotics in Skin Care: Advances, Challenges, and Future Needs

The skin, being the largest organ in the human body, plays a pivotal role in safeguarding the body against invasive pathogens. Therefore, it is essential to reinforce and protect this vital organ. Current research supports the impact of probiotics on skin health and their ability to alleviate various skin disorders. However, the effectiveness and probable side effects of probiotics in skin care remain a subject of debate, necessitating further investigation and analysis. Hence, this study aims to highlight existing gaps and future needs in the current research on probiotics in skin care and pave the way for future investigations. Therefore, we scrutinized the effects of oral (fermented foods and dietary supplements) and non-oral/topical probiotics on skin care, and the mechanism of probiotics that affect skin health. The results of most studies showed that fermented foods containing probiotics, particularly dairy products, positively impact skin health. The research results regarding the efficacy of probiotic supplements and live strains in treating skin disorders show promising potential. However, safety evaluations are crucial, to identify any potential adverse effects. While research has identified numerous potential mechanisms by which probiotics may influence skin health, a complete understanding of their precise mode of action remains elusive. However, it seems that probiotics can exert their positive effects through the gut-skin and gut-skin-brain axis on the human body. Therefore, following the identification of safe probiotics, additional studies should be carried out to establish optimal dosages, potential side effects, suitable regulatory guidelines, and validation methods.

Probiotics in Dermatology: An Evidence-based Approach

Probiotics are viable microorganisms that confer health benefits when administered to the host in adequate amounts. Over the past decade, there has been a growing demand for the use of oral and topical probiotics in several inflammatory conditions such as atopic dermatitis, psoriasis, acne vulgaris, etc., although their role in a few areas still remains controversial. The objective of this article is to shed light on understanding the origin and implications of microbiota in the pathophysiology of these dermatological conditions and the effect of probiotic usage. We have conducted a comprehensive search of the literature across multiple databases (PubMed, EMBASE, MEDLINE, and Google Scholar) on the role of probiotics in dermatological disorders. Commensal microbes of the skin and gastrointestinal tract play an important role in both health and disease. Increased use of probiotics has asserted a good safety profile, especially in this era of antibiotic resistance. With the advent of new products in the market, the indications, mechanism of action, efficacy, and safety profile of these agents need to be validated. Further studies are required. Oral and topical probiotics may be tried as a treatment or prevention modality in cutaneous inflammatory disorders, thus facilitating decreased requirement for topical or systemic steroids and antimicrobial agents. Tempering microbiota with probiotics is a safe and well-tolerated approach in this era of antimicrobial resistance.

Exploring the impact of solar radiation on skin microbiome to develop improved photoprotection strategies

The skin microbiome undergoes constant exposure to solar radiation (SR), with its effects on health well-documented. However, understanding SR's influence on host-associated skin commensals remains nascent. This review surveys existing knowledge on SR's impact on the skin microbiome and proposes innovative sun protection methods that safeguard both skin integrity and microbiome balance. A team of skin photodamage specialists conducted a comprehensive review of 122 articles sourced from PubMed and Research Gateway. Key terms included skin microbiome, photoprotection, photodamage, skin cancer, ultraviolet radiation, solar radiation, skin commensals, skin protection, and pre/probiotics. Experts offered insights into novel sun protection products designed not only to shield the skin but also to mitigate SR's effects on the skin microbiome. Existing literature on SR's influence on the skin microbiome is limited. SR exposure can alter microbiome composition, potentially leading to dysbiosis, compromised skin barrier function, and immune system activation. Current sun protection methods generally overlook microbiome considerations. Tailored sun protection products that prioritize both skin and microbiome health may offer enhanced defense against SR-induced skin conditions. By safeguarding both skin and microbiota, these specialized products could mitigate dysbiosis risks associated with SR exposure, bolstering skin defense mechanisms and reducing the likelihood of SR-mediated skin issues.

Bifidobacteria in disease: from head to toe

Bifidobacteria as a strictly anaerobic gram-positive bacteria, is widely distributed in the intestine, vagina and oral cavity, and is one of the first gut flora to colonize the early stages of life. Intestinal flora is closely related to health, and dysbiosis of intestinal flora, especially Bifidobacteria, has been found in a variety of diseases. Numerous studies have shown that in addition to maintaining intestinal homeostasis, Bifidobacteria may be involved in diseases covering all parts of the body, including the nervous system, respiratory system, genitourinary system and so on. This review collects evidence for the variation of Bifidobacteria in typical diseases among various systems, provides mild and effective therapeutic options for those diseases that are difficult to cure, and moves Bifidobacteria from basic research to further clinical applications.

Bifidobacterium longum 68S mediated gut-skin axis homeostasis improved skin barrier damage in aging mice

BACKGROUND

Bifidobacterium as probiotics, play important roles in skin status, while the potential mechanisms interaction remains unknown. The study further explored the potential mechanism of B. longum 68S in ameliorating skin barrier damage from the perspective of the gut-skin axis in aging mice.

METHODS

B. longum 68S supplied natural aging mouse model and fecal microbiota transplantation (FMT) experiment proves the key role of intestinal microbiota in B. longum 68S up-regulating the production of ceramide synthesis key enzyme (SPT1) and ceramide level and improving skin barrier damage. Moreover, B. longum 68S supplied SPT1 gene deletion mouse model to investigate the mechanism of B. longum 68S on improving skin barrier damage.

RESULTS

Transcriptome analysis and 16S rRNA high-throughput pyrosequencing demonstrated that aging mice exhibited skin barrier dysfunction and intestinal dysbiosis. Meanwhile, aging mice exhibited an up-regulation in the trans epidermal water loss (TEWL) and a down-regulation in the level of SPT1, ceramide and skin barrier-related proteins (Loricrin, Keratin 10 and Desmoglein 1). Similarity, the FMT from aging mice to normal mice and SPT1 gene deletion mice could rebuild skin barrier damage and B. longum 68S supplementation exerted a positive effect on it. Further, B. longum 68S-mediated SPT1-derived ceramide production prevented impaired ceramide synthesis-induced endoplasmic reticulum stress and apoptotic response, ultimately improving skin barrier damage in vitro.

CONCLUSION

Emerging anti-aging therapies are necessary given the poor safety profiles of current pharmaceutical drugs. B. longum 68S may be better alternatives, considering the association between the gut microbiota and healthy aging. The findings suggested that B. longum 68S-mediated gut-skin axis homeostasis, thereby exhibiting an anti-aging effect and facilitate a better understanding of the mechanisms governing the various beneficial effects of B. longum 68S.

The Role of Probiotics in Skin Health and Related Gut-Skin Axis: A Review

Aging skin, wrinkles, pigmentation, and dryness are problems that plague people, and researchers are working to solve them. Recent studies have shown that intestinal microbiota homeostasis can influence skin health, demonstrating the existence of a gut-skin axis. Recently, improving skin health through probiotic interventions has been proposed, and micro-ecological skin care is becoming a popular concept. By regulating skin health and gut-skin axis interactions, probiotics can be used as potential management tools to suppress and improve skin diseases in multiple ways, including decreasing oxidative stress, suppressing inflammatory responses, and keeping immune effects. The purpose of this paper is to provide a comprehensive review of the application and mechanisms of probiotic-mediated gut microbiota homeostasis in skin care and to offer a theoretical basis for the application of probiotics in skin care.

Effects of probiotics supplementation on skin photoaging and skin barrier function: A systematic review and meta-analysis

BACKGROUND

Ultraviolet (UV) irradiation is one of the major causes of skin aging. To date, there remains limited evidence on using oral probiotics for skin anti-photoaging.

OBJECTIVES

This systematic review and meta-analysis aims to assess the effects of probiotics on skin photoaging.

METHODS

We searched the PubMed and Embase databases for studies published until August 31, 2021, and included randomized controlled trials, murine randomized controlled experiments, and in vitro studies. Skin barrier function was compared between UV irradiated probiotics and controls.

RESULTS

After given oral probiotics supplements, a significant reduction was shown in all types of measured MMPs in both murine and in vitro studies. Oral probiotics supplementation significantly reversed UV-induced increase of epidermal thickness (standardized mean differences [SMD] = -1.76; 95% confidence interval [CI] = -3.04 to -0.49; p = .007; I²  = 81%), UV-induced increase trans-epidermal water loss (SMD = -1.72; 95% CI = -2.76 to -0.67; p = .001; I²  = 57%), and UV-induced skin dehydration (SMD = 1.85; 95% CI = 1.16 to 2.55; p < .00001; I²  = 4%).

CONCLUSIONS

Probiotics are effective against skin photoaging in terms of MMP pathways and reversing skin barrier function from murine randomized data. Further randomized controlled trials on humans are required to warrant these results.

The Effects of a Fasting Mimicking Diet on Skin Hydration, Skin Texture, and Skin Assessment: A Randomized Controlled Trial

Diet and nutrition have been shown to impact dermatological conditions. This has increased attention toward integrative and lifestyle medicine in the management of skin health. Emerging research around fasting diets, specifically the fasting-mimicking diet (FMD), has provided clinical evidence for chronic inflammatory, cardiometabolic, and autoimmune diseases. In this randomized controlled trial, we evaluated the effects of a five-day FMD protocol, administrated once a month for three months, on facial skin parameters, including skin hydration and skin roughness, in a group of 45 healthy women between the ages of 35 to 60 years old over the course of 71 days. The results of the study revealed that the three consecutive monthly cycles of FMD resulted in a significant percentage increase in skin hydration at day 11 (p = 0.00013) and at day 71 (p = 0.02) relative to baseline. The results also demonstrated maintenance of skin texture in the FMD group compared to an increase in skin roughness in the control group (p = 0.032). In addition to skin biophysical properties, self-reported data also demonstrated significant improvement in components of mental states such as happiness (p = 0.003) and confidence (0.039). Overall, these findings provide evidence for the potential use of FMD in improving skin health and related components of psychological well-being.

Topical Lactiplantibacillus plantarum LB244R® ointment alleviates skin aging: An exploratory trial

BACKGROUND

The skin is of vital importance for health and well-being. As people age, the skin undergoes visual and morphological changes such as wrinkling, loss of elasticity, increased pigmentation, and decreased cell turnover. This is not only visually unappealing to many but can also pose health issues.

AIM

In this study, a probiotic ointment (PO) containing live lactic acid bacteria (LAB) (Lactiplantibacillus plantarum LB244R®) was investigated for its ability to alleviate symptoms of skin aging in an exploratory clinical trial.

METHODS

The PO was applied twice daily for 56 days by 21 subjects. Anti-aging efficacy was evaluated by skin ultrasonography, skin biomechanical properties, skin hydration, and clinical evaluations at day 0, 28, and 56.

RESULTS

Sub-epidermal low echogenic band thickness decreased (0.261 ± 0.069 mm to 0.247 ± 0.055 mm) after 56 days. Dermal density increased (324.689 ± 57.506 pixel/mm² to 367.831 ± 75.790 pixel/mm² ). Skin hydration increased (34.1 ± 6.9 to 51.3 ± 10.0 AU). Additionally, skin firmness increased, as shown by decreasing values (0.264 ± 0.038 to 0.228 ± 0.037 mm). Skin elasticity increased (0.578 ± 0.045 to 0.618 ± 0.044). Trans-epidermal water loss decreased (9.1 ± 2.0 g/h/m² to 8.5 ± 1.3). All clinical evaluations, Crow's feet, spot score, smoothness score, and complexion radiance, were improved.

CONCLUSION

The PO improved all measured parameters with statistical significance after 56 days of application, clearly demonstrating the potential of the PO as an anti-aging agent and reaffirming the potential of topical probiotic LAB. Future studies need to elucidate the mode of action of anti-aging effects by probiotics, but at present time, this study paves the way for the use of probiotic LAB topically to alleviate aging of the skin.

Probiotics in dermatological and cosmetic products – application and efficiency

The term “probiotics” has first been used in 1907 by Elie Metchnikoff. Since then, probiotics have been part of research not only in regards of digestive health, but also inflammatory diseases. Lately, there has been an increased interest of probiotic’s effects in skincare. The management of atopic dermatitis, acne, psoriasis, photo aging, skin cancer, intimate care, oral care, wound healing is getting harder each passing day, due to increased antibiotic resistance and other side effects of conventional therapy. Therefore, new ingredients have been investigated and probiotics have been proved to be effective in treating various skin conditions. This review aims to evaluate the scientific evidence on topical and oral probiotics, and to evaluate the efficacy of cosmetic and dermatological products containing probiotics. Many studies have shown that skin and gut microbiome alterations have an important role in skin health. Although this is a new topic in dermatology and cosmetology, there have been some promising results in lots of research studies that the use of probiotics in cosmetic products may help improve the patient’s outcome. While oral probiotics have been shown to promote gut health, which influences the host immune system and helps treat different skin diseases, the mechanism of action of topical probiotics is not yet fully understood. Although the number of commercial probiotic cosmetic products released in the market is increasing and most of the studies have not shown any serious side effect of probiotics, further studies, in larger and heterogeneous groups are needed.

Prospective Placebo-Controlled Assessment of Spore-Based Probiotic Supplementation on Sebum Production, Skin Barrier Function, and Acne

Probiotic supplementation has been shown to modulate the gut-skin axis. The goal of this study was to investigate whether oral spore-based probiotic ingestion modulates the gut microbiome, plasma short-chain fatty acids (SCFAs), and skin biophysical properties. This was a single-blinded, 8-week study (NCT03605108) in which 25 participants, 7 with noncystic acne, were assigned to take placebo capsules for the first 4 weeks, followed by 4 weeks of probiotic supplementation. Blood and stool collection, facial photography, sebum production, transepidermal water loss (TEWL), skin hydration measurements, and acne assessments were performed at baseline, 4, and 8 weeks. Probiotic supplementation resulted in a decreasing trend for the facial sebum excretion rate and increased TEWL overall. Subanalysis of the participants with acne showed improvement in total, noninflammatory, and inflammatory lesion counts, along with improvements in markers of gut permeability. The gut microbiome of the nonacne population had an increase in the relative abundance of Akkermansia, while the subpopulation of those with acne had an increase in the relative abundance of Lachnospiraceae and Ruminococcus gnavus. Probiotic supplementation augmented the circulating acetate/propionate ratio. There is preliminary evidence for the use of spore-based probiotic supplementation to shift the gut microbiome and augment short-chain fatty acids in those with and without acne. Further spore-based supplementation studies in those with noncystic acne are warranted.

Lactic Acid Bacteria Improve the Photoprotective Effect via MAPK/AP-1/MMP Signaling Pathway on Skin Fibroblasts

Ultraviolet B (UVB) exposure causes a breakdown of collagen, oxidative stress, and inflammation. UVB activates mitogen-activated protein kinase (MAPK), activator protein-1 (AP-1), and matrix metalloproteinases (MMPs). In this study, we evaluated 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radical scavenging activity and the photoprotective effect of lactic acid bacteria LAB strains, including Lactobacillus, Bifidobacterium, and Streptococcus genera in UVB-exposed skin fibroblasts. Nine LAB strains displayed antioxidant activity by regulating superoxide dismutase in UVB-exposed skin fibroblasts. Four LAB strains (MG4684, MG5368, MG4511, and MG5140) recovered type I procollagen level by inhibiting MMPs, MAPK, and AP-1 protein expression. Additionally, these four strains reduced the expression of proinflammatory cytokines by inhibiting oxidative stress. Therefore, L. fermentum MG4684, MG5368, L. rhamnosus MG4511, and S. thermophilus MG5140 are potentially photoprotective.

Protective Effect of Bifidobacterium animalis subs. lactis MG741 as Probiotics against UVB-Exposed Fibroblasts and Hairless Mice

Skin photoaging, which causes wrinkles, increased epidermal thickness, and rough skin texture, is induced by ultraviolet B (UVB) exposure. These symptoms by skin photoaging have been reported to be involved in the reduction of collagen by the expression of matrix metalloproteinases (MMPs) and activator protein-1 (AP-1). This study investigated the protective effects of Bifidobacterium animalis subsp. lactis MG741 (Bi. lactis MG741) in Hs-68 fibroblasts and hairless mice (HR-1) following UVB exposure. We demonstrated that the Bi. lactis MG741 reduces wrinkles and skin thickness by downregulating MMP-1 and MMP-3, phosphorylation of extracellular signal-regulated kinase (ERK), and c-FOS in fibroblasts and HR-1. Additionally, in UVB-irradiated dorsal skin of HR-1, Bi. lactis MG741 inhibits the expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), an inflammation-related factor. Thus, Bi. lactis MG741 has the potential to prevent wrinkles and skin inflammation by modulating skin photoaging markers.

Potential anti-ageing effects of probiotic-derived conditioned media on human skin cells

In this study, the protective functions of bacteria-free conditioned media from Bifidobacterium and Lactobacillus species against ultraviolet radiation-induced skin ageing and associated cellular damage were investigated. The effects of ultraviolet radiation-induced reactive oxygen species production were suppressed by all conditioned media; particularly, the loss of cell viability and downregulation of collagen gene expression were significantly reversed by the conditioned media from B. longum and B. lactis. Further exa mination of potential anti-pigmentation effects revealed that the B. lactis-derived conditioned media significantly inhibited tyrosinase activity and alpha-melanocyte-stimulating hormone-induced melanin production in human epidermal melanocytes. Further, the conditioned media suppressed the phosphorylation of extracellular signal- related kinase, which functions as an upstream regulator of melanogenesis. Therefore, B. lactis-derived conditioned media can potentially protect against cellular damage involved in skin-ageing processes.

How Microbiomes Affect Skin Aging: The Updated Evidence and Current Perspectives

The skin has a multifactorial aging process, caused by both intrinsic and extrinsic factors. A major theory of aging involves cellular senescence or apoptosis resulting from oxidative damage as the skin’s antioxidant system tends to weaken with age. The human microbiota is a complex ecosystem that is made up of microorganisms (bacteria, fungi, and viruses). Both gut and skin microbiota have essential roles in the protection against invading pathogens, mediating inflammatory conditions, and the modulation of the immune system which is involved in both innate and adaptive immune responses. However, the human microbiome could be changed during the life stage and affected by various perturbations. An alteration of the intestinal bacteria results in “microbial dysbiosis” which is associated with the influence of various diseases, including aging. The skin interactome is a novel integration of the “genome-microbiome-exposome” that plays a significant role in skin aging and skin health. Mitigating the negative impacts of factors influencing the skin interactome should be the future strategy to protect, prevent, and delay skin aging along with preserving healthy skin conditions. This review summarizes the current evidence on how human microbiomes affect skin aging and demonstrates the possible interventions, relating to human microbiomes, to modulate skin health and aging. Probiotics-based products are currently available mainly for the add-on treatment of many dermatologic conditions. However, at this point, there are limited clinical studies on skin anti-aging purposes and more are required as this evolving concept is on the rise and might provide an insight into future therapeutic options.

Application and mechanism of probiotics in skin care: A review

BACKGROUND

Skin problems have been the focus of attention in recent years. Skin aging, wrinkles, pigmentation, dryness has been a problem that makes people feel troubled. Researchers have been devoted to find ways to solve these skin problems. Micro-ecological skin care is a popular concept these days, and improving skin health through the use of probiotics is a hot topic of discussion.

OBJECTIVE

Many experimental studies have shown that probiotics have a good effect on improving skin problems. This paper aims to comprehensively review the application and mechanism of probiotics in skin care and provide theoretical basis for the application of probiotics in skin care.

METHODS

Literatures in this review were searched in PubMed, China National Knowledge Infrastructure (CNKI), Web of Science, and Science Direct.

RESULTS

Probiotics have potent effects on skin whitening, moisturizing, anti-aging, anti-wrinkle and removing body odor.

CONCLUSIONS

The effects of probiotics on skin whitening, skin moisturizing, anti-aging, improving skin wrinkles and removing body odor were reviewed, which provided a new basis for the extensive application of probiotics in skin care.

Microbiota Targeted Interventions of Probiotic Lactobacillus as an Anti-Ageing Approach: A Review

With the implementation of modern scientific protocols, the average human lifespan has significantly improved, but age-related problems remain a challenge. With the advent of ageing, there are alterations in gut microbiota and gut barrier functions, weak immune responses, increased oxidative stress, and other age-related disorders. This review has highlighted and discussed the current understanding on the significance of gut microbiota dysbiosis and ageing and its inherent effects against age-related oxidative stress as well as on the gut health and gut-brain axis. Further, we have discussed the key mechanism of action of Lactobacillus strains in the longevity of life, alleviating gut dysbiosis, and improving oxidative stress and inflammation to provide an outline of the role of Lactobacillus strains in restoration of gut microbiota dysbiosis and alleviating certain conditions during ageing. Microbiota-targeted interventions of some characterized strains of probiotic Lactobacillus for the restoration of gut microbial community are considered as a potential approach to improve several neurological conditions. However, very limited human studies are available on this alarmed issue and recommend further studies to identify the unique Lactobacillus strains with potential anti-ageing properties and to discover its novel core microbiome-association, which will help to increase the therapeutic potential of probiotic Lactobacillus strains to ageing.

Lactobacillus rhamnosus GG Colonization in Early Life Ameliorates Inflammaging of Offspring by Activating SIRT1/AMPK/PGC-1α Pathway

Inflammaging refers to chronic, low-grade inflammation during aging, which contributes to the pathogenesis of age-related diseases. Studies have shown that probiotic intervention in the aging stage could delay aging-related disorders. However, whether the application of probiotics in early life could have antiaging effects on offspring was unknown. Here, we investigated the effects of Lactobacillus rhamnosus GG (LGG) colonization in early life on inflammaging of offspring. Pregnant mice with the same conception time were given LGG live bacteria (LC group) or LGG fixed bacteria (NC group) from the 18th day after pregnancy until natural birth. The progeny mice were treated with 10⁷ cfu of live or fixed LGG for 0-5 days after birth, respectively. LGG colonization could be detected in the feces of 3-week offspring. The 16S rRNA sequencing analysis of 3-week-old offspring showed that colonization of LGG in early life could alter the composition and diversity of gut microbiota. Interestingly, the beneficial effects of LGG colonization in early life on the microbiota lasted to 8 months old. The abundance of longevity-related bacteria (Lactobacillus, Bifidobacterium, and Akkermansia muciniphila) increased significantly in the LGG colonization group. In addition, LGG colonization increased the abundance of short-chain fatty acid- (SCFA-) producing bacteria and the production of cecal SCFAs. LGG colonization in early life protected the intestinal barrier, enhanced antioxidant defense, attenuated epithelial cell DNA damage, and inhibited intestinal low-grade inflammation in 8-month-old progeny mice. Mechanically, LGG could upregulate Sirtuin1 (SIRT1)/Adenosine 5'-monophosphate-activated protein kinase (AMPK)/Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) pathway and repress activation of nuclear factor-kappa B (NF-κB), while the protective effect of LGG was blunted after SIRT1 gene silencing. Together, LGG colonization in early life could ameliorate inflammaging of offspring, which would provide a new strategy for the prevention of age-related diseases.

The skin microbiome and the gut-skin axis

The microbiome plays a significant role in human health, homeostasis, immune system, and disease pathogenesis. Disrupted communication between the microbiome and host has been extensively studied in gastrointestinal diseases. To a lesser extent, there is emerging research on the skin microbiome and its connection with the gut, referred to as the gut-skin axis and its effects on dermatologic conditions. A basic overview will be provided of the gut and skin microbiome with a focus on the impact of this connection on cutaneous diseases, such as psoriasis, atopic dermatitis, rosacea, acne vulgaris, photoaging, and cutaneous wounds. In addition, we shall discuss nutrition-based approaches mediated through the gut-skin axis and topical treatments that could serve as potential adjunctive management by manipulation of the microbiome. In particular, there is a growing body of research on oral probiotics, prebiotics, and dietary modifications that may help improve symptoms for a variety of dermatologic conditions in select demographic groups.

Multi-Omics Interpretation of Anti-Aging Mechanisms for ω-3 Fatty Acids

Aging is one of the hottest topics in biomedicine. Previous research suggested that ω-3 fatty acids have preventive effects on aging. However, most of previous studies on the anti-aging effects of ω-3 fatty acids are focused on clinical observations, and the anti-aging mechanisms of ω-3 fatty acids have not been fully elucidated. This stimulated our interest to use multi-omics data related to ω-3 fatty acids in order to interpret the anti-aging mechanisms of ω-3 fatty acids. First, we found that ω-3 fatty acids can affect methylation levels and expression levels of genes associated with age-related diseases or pathways in humans. Then, a Mendelian randomization analysis was conducted to determine whether there is a causal relationship between the effect of ω-3 fatty acids on blood lipid levels and variation in the gut microbiome. Our results indicate that the impact of ω-3 fatty acids on aging is partially mediated by the gut microbiome (including Actinobacteria, Bifidobacteria and Streptococcus). In conclusion, this study provides deeper insights into the anti-aging mechanisms of ω-3 fatty acids and supports the dietary supplementation of ω-3 fatty acids in aging prevention.

Challenges in exploring and manipulating the human skin microbiome

The skin is the exterior interface of the human body with the environment. Despite its harsh physical landscape, the skin is colonized by diverse commensal microbes. In this review, we discuss recent insights into skin microbial populations, including their composition and role in health and disease and their modulation by intrinsic and extrinsic factors, with a focus on the pathobiological basis of skin aging. We also describe the most recent tools for investigating the skin microbiota composition and microbe-skin relationships and perspectives regarding the challenges of skin microbiome manipulation. Video abstract.

Boosting the Photoaged Skin: The Potential Role of Dietary Components

Skin photoaging is mainly induced by ultraviolet (UV) irradiation and its manifestations include dry skin, coarse wrinkle, irregular pigmentation, and loss of skin elasticity. Dietary supplementation of nutraceuticals with therapeutic and preventive effects against skin photoaging has recently received increasing attention. This article aims to review the research progress in the cellular and molecular mechanisms of UV-induced skin photoaging. Subsequently, the beneficial effects of dietary components on skin photoaging are discussed. The photoaging process and the underlying mechanisms are complex. Matrix metalloproteinases, transforming growth factors, skin adipose tissue, inflammation, oxidative stress, nuclear and mitochondrial DNA, telomeres, microRNA, advanced glycation end products, the hypothalamic-pituitary-adrenal axis, and transient receptor potential cation channel V are key regulators that drive the photoaging-associated changes in skin. Meanwhile, mounting evidence from animal models and clinical trials suggests that various food-derived components attenuate the development and symptoms of skin photoaging. The major mechanisms of these dietary components to alleviate skin photoaging include the maintenance of skin moisture and extracellular matrix content, regulation of specific signaling pathways involved in the synthesis and degradation of the extracellular matrix, and antioxidant capacity. Taken together, the ingestion of food-derived functional components could be an attractive strategy to prevent skin photoaging damage.

The Role of Bifidobacteria in Predictive and Preventive Medicine: A Focus on Eczema and Hypercholesterolemia

Bifidobacteria colonize the human gastrointestinal tract early on in life, their interaction with the host starting soon after birth. The health benefits are strain specific and could be due to the produced polysaccharides. The consumption of probiotics may prevent obesity, irritable bowel syndrome, eczema or atopic dermatitis, and asthma. Non-replicative strains of Bifidobacterium longum (NCC3001 and NCC2705) promote the differentiation of normal human epidermal keratinocytes (NHEKs), inducing a high expression of differentiation markers (keratin —KRT1—, and transglutaminase —TGM1—) and pro-regeneration markers (cathepsins), including β-defensin-1, which plays an important role in modulating the cutaneous immune response. Strains belonging to the genera Bifidobacterium and Lactobacillus can increase tight-junction proteins in NHEKs and enhance barrier function. Bifidobacteria and lactobacilli may be used as prophylactic or therapeutic agents towards enteric pathogens, antibiotic-associated diarrhea, lactose intolerance, ulcerative colitis, irritable bowel syndrome, colorectal cancer, cholesterol reduction, and control of obesity and metabolic disorders. Bifidobacterium bifidum showed an in vitro capability of lowering cholesterol levels thanks to its absorption into the bacterial membrane. Several strains of the species Lactobacillus acidophilus, L. delbrueckii subsp. bulgaricus, L. casei, and L. gasseri led to a reduced amount of serum cholesterol due to their ability to assimilate cholesterol (in vitro). Lactococcus lactis KF147 and Lactobacillus plantarum Lp81 have also been shown to reduce cholesterol levels by 12%. Clarifying the specific health mechanisms of Bifidobacterium and Lactobacillus strains in preventing high-cost pathologies could be useful for delineating effective guidelines for the treatment of infants and adults.

Functional Role of Probiotics and Prebiotics on Skin Health and Disease

Scientific and commercial interest of probiotics, prebiotics and their effect on human health and disease has increased in the last decade. The aim of this review article is to evaluate the role of pro- and prebiotics on the normal function of healthy skin as well as their role in the prevention and therapy of skin disease. Lactobacilli and Bifidobacterium are the most commonly used probiotics and thought to mediate skin inflammation, treat atopic dermatitis (AD) and prevent allergic contact dermatitis (ACD). Probiotics are shown to decolonise skin pathogens (e.g., P. aeruginosa, S. aureus, A. Vulgaris, etc.) while kefir is also shown to support the immunity of the skin and treat skin pathogens through the production of antimicrobial substances and prebiotics. Finally, prebiotics (e.g., Fructo-oligosaccharides, galacto-oligosaccharides and konjac glucomannan hydrolysates) can contribute to the treatment of diseases including ACD, acne and photo aging primarily by enhancing the growth of probiotics.

Protective effects of tyndallized Lactobacillus acidophilus IDCC 3302 against UVB‑induced photodamage to epidermal keratinocytes cells

Photoaging is a consequence of chronic exposure to ultraviolet (UV) radiation and results in skin damage. In this study, whether tyndallizate of the probiotic bacterium Lactobacillus acidophilus IDCC 3302 (ACT 3302) can protect against UVB‑induced photodamage to the skin was investigated. For this, HaCaT keratinocytes were used as a model for skin photoaging. HaCaT cells were treated with ACT 3302 prior to UVB exposure and skin hydration factors and matrix metalloproteinase (MMP)‑1, MMP‑2, and MMP‑9 levels in the culture supernatant were evaluated by ELISA. The protective effects of ACT 3302 against UVB‑induced oxidative stress in HaCaT cells was also assessed by measuring superoxide dismutase and catalase activity and detecting the expression of pro‑inflammatory cytokine‑encoding genes and mitogen‑activated protein kinase (MAPK) signaling components by reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. UVB exposure increased MMP expression and MAPK activation; these changes were attenuated by pretreatment with ACT 3302. Treatment with ACT 3302 prior to UVB exposure also attenuated inflammation. These results demonstrate that tyndallized ACT 3302 can mitigate photodamage to the skin induced by UVB radiation through the suppression of MMPs and could therefore be used clinically to prevent wrinkle formation.

Probiotics in Extraintestinal Diseases: Current Trends and New Directions

Probiotics are defined as live microorganisms that when administered in adequate amounts confer a health benefit to the host. Their positive supplementation outcomes on several gastrointestinal disorders are well defined. Nevertheless, their actions are not limited to the gut, but may also impart their beneficial effects at distant sites and organs. In this regard, in this review article we: (i) comprehensively describe the main mechanisms of action of probiotics at distant sites, including bones, skin, and brain; (ii) critically present their therapeutic potential against bone, skin, and neuronal diseases (e.g., osteoporosis, non-healing wounds and autoimmune skin illnesses, mood, behavior, memory, and cognitive impairments); (iii) address the current gaps in the preclinical and clinical research; and (iv) indicate new research directions and suggest future investigations.

Lactobacillus plantarum HY7714 Restores TNF-α Induced Defects on Tight Junctions

In addition to intestinal balance, probiotics are known to have beneficial effects on skin inflammation, metabolic diseases, and emotions. Previously, we have reported the skin anti-aging effects of Lactobacillus plantarum HY7714 (HY7714) in a clinical trial. To prove the protective skin effects of HY7714 through the intestinal tight junction (TJ), we investigated the effects of HY7714 on the intestines through tumor necrosis factor (TNF)-α induced TJ defects in Caco-2 cells. Specifically, 24 h treatment with HY7714 restored the decreased expression of zonula occludens-1, occludin, and claudin-1 compared to the TNF-α-treated groups (P<0.05). It also attenuated the level of pro-inflammatory cytokines interleukin-6, 8, and 1β. Further, increases in the mRNA levels of Elk-1, nuclear factor-κB, and myosin light chain kinase expression induced by TNF-α were recovered by HY7714. These findings imply that HY7714 improves intestinal barrier integrity and is a potential therapeutic agent for dysfunctions derived from TJ defects.

Purified thioredoxin reductase from O2-sensitive Bifidobacterium bifidum degrades H2O2 by interacting with alkyl hydroperoxide reductase

Bifidobacterium is beneficial for host health and exhibits different O₂ sensitivity levels among species or strains via unknown mechanisms. Bifidobacterium bifidum JCM1255^T, a type species of Bifidobacterium, is an O₂-sensitive bacterium that can grow under low-O₂ (5%) conditions, and the growth of this species is inhibited under high-O₂ conditions (10% ∼) with accumulation of H₂O₂. We previously reported that NADH or NAD(P)H oxidase-active fractions were detected during purification using microaerobically grown B. bifidum cells, and the active enzyme was purified from the NADH oxidase-active fraction. The purified enzyme was identified as b-type dihydroorotate dehydrogenase (DHODb) and characterized as a dominant H₂O₂ producer in B. bifidum. In this study, we performed further purification of the enzyme from the NAD(P)H oxidase-active fraction and characterized the purified enzyme as a part of the H₂O₂ degradation system in B. bifidum. This purified enzyme was identified as thioredoxin reductase (TrxR); the NAD(P)H oxidase activity of this enzyme was not expressed in anaerobically grown B. bifidum, and mRNA expression was induced by O₂ exposure. Furthermore, the purified B. bifidum TrxR interacted with recombinant alkyl hydroperoxide reductase (rAhpC) and exhibited NAD(P)H peroxidase activity. These results suggest that TrxR responds to O₂ and protects B. bifidum from oxidative stress by degrading H₂O₂ via the TrxR-AhpC system.

Skin Moisturizing and Antiphotodamage Effects of Tyndallized Lactobacillus acidophilus IDCC 3302

Photoaging is generally the result of chronic exposure to the sun and ultraviolet (UV) radiation, which causes skin damage. In this study, we developed a UVB-induced hairless mouse model to determine whether Lactobacillus acidophilus IDCC 3302 tyndallizate (ACT3302) can enhance photodamaged skin repair. Mice (6 weeks old) were divided into six groups containing normal, UVB-treated vehicle, and UVB-treated ACT3302 (1 × 10⁵, 1 × 10⁶, 1 × 10⁷, and 1 × 10⁸ cells). Epidermal thickness was increased by UVB, but the thickening was lessened by ACT3302 as was the transepidermal water loss (TEWL). However, ACT3302 increased capacitance and decreased TEWL. Skin tissue staining to evaluate skin collagen increases in the number of skin collagen bundles in UVB-treated ACT3302 mice. UVB irradiation increased matrix metalloproteinase (MMP) and proinflammatory cytokine expression and activated mitogen-activated protein kinases in hairless mice; these changes were also attenuated by ACT3302. We conclude that ACT3302 effectively suppressed wrinkle formation induced by UVB irradiation through MMP downregulation. Therefore, ACT3302 potentially prevents skin photoaging and wrinkle formation.

Origination, change, and modulation of geriatric disease-related gut microbiota during life

The age-related changes in the diversity and composition of the gut microbiota are well described in recent studies. These changes have been suggested to be influenced by age-associated weakening of the immune system and low-grade chronic inflammation, resulting in numerous age-associated pathological conditions. Gut microbiota homeostasis is important throughout the life of the host by providing vital functions to regulate various immunological functions and homeostasis. Based on published results, we summarize the relationship between the gut microbiota and aging-related diseases, especially Parkinson's disease, immunosenescence, rheumatoid arthritis, bone loss, and metabolic syndrome. The change in composition of the gut microbiota and gut ecosystem during life and its influence on the host immunologic and metabolic phenotype are also analyzed to determine factors that affect aging-related diseases. Approaches to maintain host health and prevent or cure geriatric diseases are also discussed.

The green tea modulates large intestinal microbiome and exo/endogenous metabolome altered through chronic UVB-exposure

The attenuating effects of green tea supplements (GTS) against the ultraviolet (UV) radiation induced skin damages are distinguished. However, the concomitant effects of GTS on the large intestinal microbiomes and associated metabolomes are largely unclear. Herein, we performed an integrated microbiome-metabolome analysis to uncover the esoteric links between gut microbiome and exo/endogenous metabolome maneuvered in the large intestine of UVB-exposed mice subjected to dietary GTS. In UVB-exposed mice groups (UVB), class Bacilli and order Bifidobacteriales were observed as discriminant taxa with decreased lysophospholipid levels compared to the unexposed mice groups subjected to normal diet (NOR). Conversely, in GTS fed UVB-exposed mice (U+GTS), the gut-microbiome diversity was greatly enhanced with enrichment in the classes, Clostridia and Erysipelotrichia, as well as genera, Allobaculum and Lachnoclostridium. Additionally, the gut endogenous metabolomes changed with an increase in amino acids, fatty acids, lipids, and bile acids contents coupled with a decrease in nucleobases and carbohydrate levels. The altered metabolomes exhibited high correlations with GTS enriched intestinal microflora. Intriguingly, the various conjugates of green tea catechins viz., sulfated, glucuronided, and methylated ones including their exogenous derivatives were detected from large intestinal contents and liver samples. Hence, we conjecture that the metabolic conversions for the molecular components in GTS strongly influenced the gut micro-environment in UVB-exposed mice groups, ergo modulate their gut-microbiome as well as exo/endogenous metabolomes.

The role of microbiota, and probiotics and prebiotics in skin health

During the past decade, scientists have made great strides in understanding the microbiome's role in human health. Today, the microbiome has become key in scientific research, therapeutic development, medical treatment, and as a news feature in the media. Most studies have focused on the microbiome of our gut, but recently researchers have turned their attention to other microbiomes, including that of the skin. These studies of gut and skin microbiomes are yielding very informative results, new treatment strategies, and the development of new prebiotic and probiotic products for the treatment of many skin conditions.

Gut microbiota: A player in aging and a target for anti-aging intervention

Aging-associated alterations in composition, diversity and functional features of intestinal microbiota are well-described in the modern literature. They are suggested to be caused by an age-related decline in immune system functioning (immunosenescence) and a low-grade chronic inflammation (inflammaging), which accompany many aging-associated pathologies. The microbiota-targeted dietary and probiotic interventions have been shown to favorably affect the host health and aging by an enhancement of antioxidant activity, improving immune homeostasis, suppression of chronic inflammation, regulation of fat deposition and metabolism and prevention of insulin resistance. Recently, a high effectiveness and safety of novel therapeutic application such as fecal microbiota transplantation in the prevention and treatment of age-related pathological conditions including atherosclerosis, type 2 diabetes and Parkinson's disease has been demonstrated. In this review, recent research findings are summarized on the role of gut micribiota in aging processes with emphasis on therapeutic potential of microbiome-targeted interventions in anti-aging medicine.