Even though bacteria such as Propionibacterium acnes share the same genus and species, says an expert, recent research suggests that different P. acnes strains may behave differently, which could have profound implications for acne treatment.
Miami Beach, Fla. - Even though bacteria such as Propionibacterium acnes share the same genus and species, says an expert, recent research suggests that different P. acnes strains may behave differently, which could have profound implications for acne treatment.
Previously, says Whitney P. Bowe, M.D., “Most researchers felt comfortable classifying bacteria based on their genus and species. However, a new study adds yet another level of detail to the probiotic story.” Dr. Bowe is a dermatologist based in New York City and Westchester, N.Y. She is clinical assistant professor of dermatology, State University of New York Downstate Medical Center.
The study, conducted at the University of California, Los Angeles, spotlights the importance of identifying the particular strain of bacteria, not just the genus and species, she says. To characterize the population structure and diversity of P. acnes at the strain level, investigators compared samples from the nasal pilosebaceous units of 49 patients with acne and 52 healthy controls.
“By sequencing 66 previously unreported P. acnes strains and comparing 71 P. acnes genomes,” the authors wrote, “we identified potential genetic determinants of various P. acnes strains in association with acne or health (Fitz-Gibbon S, Tomida S, Chiu BH, et al. J Invest Dermatol. 2013 Jan 21. [Epub ahead of print]).”
In short, certain strains were strongly associated with the presence of acne, while other strains dominated in patients without acne. This suggests that, along with the quantity of bacteria present, dermatologists might have to consider the particular strains of P. acnes with which the patient is colonized, Dr. Bowe says. Based on this study, she adds, “One particular strain of P. acnes might actually protect the host from developing acne.”
Going forward, “We need additional research to identify which strains and species are most beneficial not only for acne, but also for other chronic diseases such as rosacea and atopic dermatitis.”
Dermatologists also must explore the best mode of delivery for these strains, she says. Options include topical application (creams, lotions and cleansers), and oral supplementation (capsules, lozenges and probiotic-containing foods such as yogurt).
In the latter area, a Korean study has demonstrated that patients with acne who drank fermented milk fortified with lactoferrin daily for 12 weeks experienced significant improvement in lesion counts and clinical acne grades, as well as reductions in sebum levels, versus those who drank fermented milk without the added lactoferrin (Kim J, Ko Y, Park YK, et al. Nutrition. 2010;26:902-909). Although the lactoferrin-enriched product achieved better results, Dr. Bowe says, “The benefits observed in patients who drank the unaccompanied probiotic drink suggest that probiotics might play an adjuvant role in acne therapy.”
Oral probiotics impact the gut-brain-skin axis (Bowe WP, Logan AC. Gut Pathog. 2011;3(1):1). More specifically, Dr. Bowe explains, probiotics and their metabolites interact with gut associated lymphoid tissue (GALT), which makes up nearly 70 percent of the immune system. “Through this interaction, the immune system learns to make good decisions about how it will respond to pathogens, allergens or commensal bacteria in the future.”
On a broader level, she says, psychological stress such as anxiety or depression - alone or combined with the consumption of processed comfort foods lacking in fiber - slows gut motility and changes the gastrointestinal flora by increasing the ratio of “unhealthy” organisms to healthy ones.
“In turn, this leads to increased intestinal permeability.” In this regard, Dr. Bowe says, receptors on human intestinal cells recognize bacteria and bacterial cell wall components. When these receptors encounter healthy bacteria, “The gut barrier remains intact. But when these receptors encounter unhealthy bacteria, it impacts the junctions between intestinal cells, causing a ‘leaky’ gut.”
When this happens, systemic inflammation, and markers thereof, increase, Dr. Bowe says. Other consequences include elevation of substance P, and a decrease in insulin sensitivity. In people already genetically predisposed to acne or rosacea, “This cascade is believed to influence the skin and potentially exacerbate these conditions,” she says.
Additionally, studies have shown that oral probiotics regulate the release of inflammatory cytokines within the skin (Hacini-Rachinel F, Gheit H, Le Luduec JB, et al. PLoS One. 2009;4(3):e4903) and improve insulin sensitivity in animal models (Hsieh FC, Lee CL, Chai CY, et al. Nutr Metab (Lond). 2013;10(1):35). “These findings are relevant in light of recent studies linking high glycemic-index diets with acne,” Dr. Bowe says.
Disclosures: Dr. Bowe is a co-inventor of patent USPN 8,415,289 Bacterial-Derived BLIS for treatment of acne. She recently filed a Return to Inventor Application (UPENN Docket No. S4013, supported by the University of Pennsylvania).
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