The skin is home to a diverse mix of microorganisms including bacteria, fungi, protozoa and viruses known as the ‘skin microbiome’.
New research from a team of European Academy of Allergy & Clinical Immunology (EAACI) researchers provides a complete list of lifestyle and environmental factors that impact the skin microbiome and can aid future skin care product development.
The study explores how the balance of this microbiota is key to maintaining skin homeostasis, protecting against pathogens and interacting with the body’s immune system. Meanwhile, disruption of this balance (dysbiosis) is associated with various skin conditions.
The findings, published in the European Journal of Allergy & Clinical Immunology, can be used to inform both preventative and therapeutic approaches to skin conditions and also highlight potential applications for the cosmetic and dermatological industries focused on microbiome compatibility.
Key findings from the research
Some of the main findings concluded that:
- Skin microbiota composition is variable both geographically and anatomically. It is influenced by environmental factors like temperature, pH, sebum production and hydration levels. It also contributes to barrier function, antimicrobial activity and immune modulation, which means it plays a protective role against disease.
- A stable and diverse skin microbiota is linked to the resilience and proper function of the cutaneous barrier. ‘Friendly’ bacteria compete with potential pathogens, secrete antimicrobial peptides (AMPs) and communicate with host immune cells to modulate immune response.
- Dysbiosis (disruption of the skin microbiome balance) can result from both intrinsic and extrinsic factors and is related to inflammatory skin disorders like atopic dermatitis, acne vulgaris and psoriasis.
- Lifestyle influences contribute to the health of the skin microbiome. For example, with circadian rhythms, skin microbial diversity fluctuates diurnally. This has implications for barrier function and immune responses, while disruptions to sleep and circadian habits can potentially worsen inflammatory skin conditions.
- The intersection of diet, gut health and skin microbiota shows a bidirectional relationship where nutrients affect microbial composition, influencing systemic inflammation and skin conditions.
- While there are potential benefits of exercise on microbiota diversity, the relationship between physical activity, sweat and microbial shifts needs more exploration, with a particular focus on contact sports and their associated risks for skin infections.
- Effective hygiene practices support microbial homeostasis, but excessive antimicrobial use can lead to disruptions. Although the findings emphasize proper handwashing and its role in skin microbiota diversity.
The role of environmental factors
Environmental factors were also explored, with findings including:
- Increased urban environments correlated with reduced skin microbial diversity and higher incidences of skin disorders.
- Exposure to environmental stressors such as particulate matter and volatile organic compounds altered skin’s microbial community, which potentially lead to skin inflammation and conditions.
- The impact of heavy metals and other pollutants on microbial resilience is a critical area for future research.
- While UV radiation can benefit skin health by promoting vitamin D synthesis and AMPs, excessive UV exposure has a dramatic effect on microbial populations. A balanced approach to sun exposure is needed in for optimum skin health.
Skin microbiome: ‘A crucial function for human health’
Dr. Chris Callewaert, senior post-doctoral researcher at the Center for Microbial Ecology and Technology at Ghent University and one of the co-authors of the study, said that many of these influences are in the hands of the individuals themselves.
“The diet you consume, the hygiene habits you choose, the products you buy that you get on your skin, the sedentary/active lifestyle, the sleep you get,” he explained. “Perhaps a good new year’s resolution is to take good care of your body, while also protecting the skin microbiome.”
He added there are also many external factors beyond an individual’s control like sun and pollution exposure, hot/cold climate and contact with nature.
The research also serves to highlight the presence and importance of the skin microbiome, particularly for R&D.
“It is there and has a crucial function for human health,” he said.
“When creating a face cream, deodorant, sunscreen, skin moisturizer, shampoo, eczema product, it is important to take into account the skin microbiome and their potential modulation. By all means, the skin microbiome cannot be modulated to enrich the pathogens.”
Exposome, epigenetics and the microbiome
Dr. Callewaert previewed that the EAACI task force is currently working on a follow-up review on the internal factors that can determine skin microbiome, such as age, biological sex, hormones, genetics, skin pH, immune system and stress.
“These are influences coming from inside our body that also steer the microbiome for a large part,” he said. “All of these factors are part of the exposome, part of the epigenetics, that determine how and if we get autoinflammatory diseases and how our immune system is trained.”
Dr. Callewaert added that those factors are far more important than genetics alone.
“That is the main reason why in Western society we all have some form of autoinflammatory pathology (be it acne or cardiovascular diseases or cancer) and why people living a traditional hunter-gatherer lifestyle never have any cancer, acne, eczema or stress,” he explained.
“They are among the happiest people in the world. They barely have any wrinkles or grey hair, while they are usually exposed to sun all the time. We envision an important protective element of the skin microbiome.”