Importance of Skin-Gut Axis Communication in Homeostasis
The review explored the “emerging” term gut-skin axis and aimed to decipher the bidirectional signaling of the skin and gastrointestinal tract during homeostatic and disease states.
Researchers identified a dynamic relationship between the skin and gastrointestinal organs, which both play a crucial role in maintaining homeostasis, according to data published in Gut Microbes.1
“The human body develops and grows while in constant contact with its external environment, primarily through 2 interfaces, namely the skin and the gastrointestinal (GI) tract,” wrote authors of the study. “Both sites receive an array of environmental signals that are transduced to deeper tissues, usually eliciting beneficial and/or homeostatic responses. Unfortunately, they also represent vulnerable target sites for both biotic and abiotic threats.”
When it comes to biotic threats, acne is the most common skin condition in the US, affecting close to 50 million Americans each year.2 For GI diseases, according to the American College of Gastroenterology, irritable bowel syndrome is the most common disease diagnosed by gastroenterologists.3
Researchers explored the emerging skin-and-gut-health relationship and highlighted the importance of how each organ communicates with the other. | image credit: bonnontawat / stock.adobe.com
While these conditions are often revealed through notable symptoms and diagnoses from a health care provider, other abiotic threats could be just as demoralizing as biotic threats from various skin or GI conditions.
READ MORE: Social Media Significantly Influences Attitudes, Behaviors Toward Skin Health
“Furthermore, [the skin and the gut] are both extensively vascularized and innervated, allowing rapid communication with the immune and central nervous systems, thereby facilitating rapid responses to environmental threats,” continued the authors.1 “Notably, both surfaces host diverse communities of commensal microbes, collectively known as the microbiome.”
Amid growing evidence that supports a unique and crucial link between the skin and the gut—what researchers refer to as the gut-skin axis (GSA)—they wanted to better understand the gut-to-skin relationship and focus on how the environment plays a role.
“This review provides a summary of recent findings that support the concept of bidirectional communication between the skin and the gut, as well as the roles played by various molecular players, including but not limited to microbial metabolites, signaling molecules, and environmental factors,” the authors wrote. “By elucidating these pathways, we seek to deepen our understanding of how diverse environmental signals promote tissue homeostasis, as well as propose that ultraviolet b (UVB) light may offer a novel therapeutic approach for the human GI tract, acting via the GSA.”
Before diving into the role of environmental factors on the GSA, researchers explored the emerging skin-and-gut-health relationship, highlighting the importance of how each organ communicates with the other. The key player that facilitates communication between the skin and the gut is the microbiota in each organ system, along with various metabolites and micronutrients.
Next, they touched on the routes of communication between the gut and the skin, explaining how general knowledge of 1-way communication from the gut to the skin is much more robust than communication from the skin to the gut. However, through environmental exposures, especially those from the sun, researchers of the current review put a spotlight on the skin’s ability to communicate with the gut.
While it is known that vitamin D consumption can impact the gut, and sun exposure can impact the skin, a study explored in the review showed how vitamin D exposure of the skin can play a role in changing the gut microbiome.
“Recently, exposing the skin to UVB light was shown to modulate the gut microbiota composition of vitamin D insufficient, but otherwise healthy, women,” they wrote.1 “In both the skin and gut, vitamin D receptor activation plays a critical role in regulating the production of antimicrobial peptides such as cathelicidin, which help maintain microbiota homeostasis and provide protection against pathogens.”
Finally, they explored the potential for using UV radiation as a therapeutic treatment option for patients experiencing conditions linked to the GSA. While vitamin D has previously shown capabilities of displaying protective properties against immune-mediated disorders, concentrated UV radiation has also been explored for its therapeutic effects on the GSA, not just the skin.
“UV radiation has been investigated for its potential therapeutic effects on the skin, with studies suggesting that it can impact the cutaneous immune system through the GSA,” continued the authors.1 “An exciting concept is that sunlight, particularly UVB light, may offer protective properties against a range of immune-mediated disorders, extending beyond the conventional role of vitamin D.”
Despite the current consensus being that UV radiation as a therapy still needs to be developed further, the findings in this review have the ability to inform many providers and patients experiencing GSA challenges on a day-to-day basis. With the discovery of further evidence supporting the GSA relationship, more avenues of research for this crucial relationship will be opened up.
“In conclusion, our review highlights the dynamic communication in the skin and gut axis. While the various organs interact, these 2 organs are uniquely exposed to the environment, and play a crucial role in maintaining homeostasis, and balancing between beneficial and detrimental effects of environmental factors,” concluded the authors.1 “Ultimately, further research will help to clarify how environmental stimuli such as UV treatment can control the complex signaling networks that control human health and disease, offering prospects for improved patient outcomes and enhanced health care practices.”
READ MORE: Dermatology Resource Center
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