Acne and the Gut Microbiome
Acne vulgaris is an inflammatory condition affecting hair follicles and oil producing and secreting (also called sebaceous) glands. Acne is defined by skin eruptions of various forms including pimples – whiteheads or blackheads- papules, pustules, nodules, and cysts. This disorder is exceedingly common, estimated to affect 90% of teenagers and – in a recent study – approximately 9.8% of the global population with burden of disease most significant in Western Europe, Asia Pacific, and East Asia. It can affect all races, genders, and ages, though is most prevalent in adolescents, likely because sex hormones rise during puberty which result in increased oil production by the sebaceous glands. One specific type of bacteria called Cutibacterium acnes (previously Propionibacterium acnes) has been implicated in development of acne due to its predominance in skin areas rich in oil producing (sebaceous) glands. While bacterial proliferation may play a role, research has suggested that the pathogenesis is more complicated and may in an analogous fashion as in the gut, involve an interaction between skin, gut microbes, and host immunity through a proposed gut-brain-skin axis. Understanding this complex interaction may allow for more comprehensive treatment approaches.
“While bacterial proliferation may play a role, research has suggested that the pathogenesis is more complicated and may in an analogous fashion as in the gut, involve an interaction between skin, gut microbes, and host immunity through a proposed gut-brain-skin axis.”
Understanding the Gut-Brain-Skin Axis
A connection between the gastrointestinal system, the brain/psyche, and acne was first proposed in 1930 by two dermatologists, Dr. Stokes, and Dr. Pillsbury. They suggested a gut-brain-skin ‘emotional linkage theory’ describing how mood states such as depression and anxiety influence the gut and its microbiome, which can lead to increased intestinal permeability (“leaky gut”) with local and widespread inflammation seen through skin eruptions. Hormone changes, oil production, dietary changes, and certain medications have also been implicated in the development of acne. It has also become increasingly clear that the immune system is involved, with 70-80% of immune cells being located in the gut. Optimal immunity requires a successful interplay between the microbes within the intestinal lining and the local mucosal immune system and influences overall immunity of the host. Further evidence for the gut-brain-skin axis comes from studies that have shown constipation is more common among adolescents with acne, who have lower levels of Lactobacillus and Bifidobacterium, increased intestinal permeability, and enhanced immune response.
“Optimal immunity requires a successful interplay between the microbes within the intestinal lining and the local mucosal immune system and influences overall immunity of the host.”
Role of Probiotics in Acne Treatment?
Traditional therapies for acne have historically neglected to address the brain or gut component and generally are aimed at addressing hormone production and bacterial flora. They follow a “step up” approach, starting with more mild regimens and progress to stronger ones as necessary to control the skin outbreaks. A patient’s individual factors such as age, location, duration, and extent of acne must also be considered. First line topical medications in the form of creams, lotions, gels, or solutions are benzoyl peroxide (kills bacteria), retinoids (unclog pimples by encouraging cell turnover), and salicylic acid. The next level of treatment includes oral medications, primarily antibiotics, such as doxycycline and erythromycin (both with anti-inflammatory properties), trimethoprim (alone or combined with sulfamethoxazole), and – in most severe cases – oral isoretinoin. All of these medications come with side effects of varying degrees of severity from sun sensitivity to GI upset to mood swings. A decrease in gut microbial diversity and richness, and the development of bacterial resistance are also serious consequences of repeated courses of antibiotics, and the latter has decreased the efficacy of antibiotic therapies.
“Traditional therapies for acne have historically neglected to address the brain or gut component and generally are aimed at addressing hormone production and bacterial flora.”
Probiotics, defined in a Food and Agriculture Organization and World Health Organization consensus statement as “live microorganisms which when administered in adequate amounts confer a health benefit on the host,” may offer a supplemental treatment option for acne sufferers. Over the past decade, probiotics have gained public interest for their health promoting benefits, though robust evidence has thus far only supported use of a few strains when applied in very specific conditions. Dr. Stokes and Dr. Pillsbury first recommended use of L. acidophilus fermented milk products as a treatment modality for the gut-brain-skin axis. Since then, multiple studies have presented evidence that oral probiotics as an adjunct to standard acne therapies can improve antibiotic tolerance, facilitate clinical improvement, and even reduce lesions and oil an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. Production. Topical probiotics also show promise for their anti-microbial and anti-inflammatory properties.
There is much more to be learned about the gut-brain-skin axis and significant potential for more mainstream multi-modal therapeutic approaches to the management of acne. A better understanding of the interaction between the gut microbiome, immune system, and inflammation in development of dermatologic conditions will offer an opportunity for the development of comprehensive therapies to improve quality of life for those affected.
MariaLisa Itzoe, DO, MPH is an Internal Medicine resident at Pennsylvania Hospital of the University of Pennsylvania, with a passion for helping patients who experience disorders of brain-gut interaction. She has a special interest in neuro-gastroenterology and health communication. MariaLisa is also a certified yoga instructor who loves cooking and sharing nutritious meals with family and friends.