Microencapsulated benzoyl peroxide shifts skin microbiome in rosacea

Microencapsulated benzoyl peroxide improved rosacea and shifted the skin microbiome after 8 weeks, reducing Staphylococcus epidermidis and increasing Cutibacterium acnes. Furthermore, the authors of the current study argued that an increase in the histidine degradation pathway may be indicative of a functional change in the skin.

“Benzoyl peroxide, if normally formulated, is highly reactive and not well tolerated by patients with rosacea,” Prof. Raja Sivamani (Pacific Skin Institute, CA, USA) started his presentation [1]. “In fact, it will create more inflammation and free radical damage. However, microencapsulated benzoyl peroxide is efficacious and well tolerated. Our aim is not to figure out if it works, but why it works.” Participants with rosacea were randomised to receive microencapsulated benzoyl peroxide (n=15) or a placebo (n=16). The main purpose of the study was to evaluate changes to the skin microbiome. Prof. Sivamani emphasised that the study method only allowed for the collection of aerobic environments and not anaerobic environments.

After 8 weeks of treatment, no difference was observed in the Shannon diversity index in either the active group or the placebo group. “However, looking at the actual genera, a couple of bacteria drew our attention,” Prof. Sivamani added. A non-significant slight reduction in Staphylococcus epidermidis (P=0.11) and an increase in Cutibacterium acne (P=0.034) were reported from baseline to week 8 in the active treatment group. These shifts were not observed in the placebo arm. Furthermore, a significant elevation in the histidine degradation pathway was reported in the active arm. “If the microbes are degrading histidine, the thought is that they are being delivered more histidine,” argued Prof. Sivamani. “And histidine is one of the vital amino acids of the skin barrier. In combination with the improvement in rosacea, we argue that histidine utilisation is going up, reflecting the improved skin barrier that we observed from the clinical data.”

In conclusion, microencapsulated benzoyl peroxide improved rosacea symptoms by shifting the skin microbiome. The changes observed in the histidine degradation pathway suggest a functional change in the skin as well. “The next step is to analyse whether changes in the skin microbiome persist after the treatment is ended,” Prof. Sivamani concluded.

1. Sivamani RK, et al. Microencapsulated Benzoyl Peroxide Cream, 5% Effects on the Microbiome of the Skin in Subjects With Moderate to Severe Rosacea. Late-breaker Session 1, WCD 2023, 3-8 July, Singapore, Singapore.