Topical microencapsulated benzoyl peroxide may improve rosacea by shifting skin microbiome

Key takeaways:

• A reduced abundance of Staphylococcus epidermidis correlated with improved rosacea.
• Patients treated with microencapsulated benzoyl peroxide had improved sebum level, facial erythema and inflammation.

Topical microencapsulated benzoyl peroxide improved the skin microbiome and physical properties and clinical symptoms among patients with rosacea, according to results of a study published in Journal of Clinical and Aesthetic Dermatology.

“Imbalances in cutaneous organisms (eg, Staphylococcus epidermidis, Cutibacterium acnes, Demodex folliculorum, and Bacillus oleronius) have been implicated in the pathogenesis of rosacea,” Yvonne Nong, MD, MS, with Integrative Skin Science and Research, the Pacific Skin Institute and the department of dermatology at University of California, Davis and colleagues wrote.

Although the mechanism of action is unknown, Nong and colleagues theorized that the antimicrobial properties of microencapsulated benzoyl peroxide (E-BPO) may contribute to its efficacy as a treatment for rosacea.

To further investigate changes in the skin microbiome and physical properties following treatment with E-BPO, Nong and colleagues conducted a randomized, double-blind, crossover, single-center vehicle-controlled study from February 2020 to July 2021 that included 31 patients with facial rosacea who had an IGA severity score of 3 (moderate) or 4 (severe).

Researchers randomly assigned patients to receive a pea-sized amount of topical E-BPO 5% (n = 15) or vehicle cream (n = 16) once daily for 8 weeks, after which they switched to the opposite treatment for 4 weeks.

The researchers performed clinical assessments for rosacea inflammation, inflammatory lesion counts and erythema at baseline and weeks 1, 2, 4, 8, 12 and 16. They measured facial sebum excretion rates using Sebumeter (Courage + Khazaka) and changes in the skin microbiome using DNA extraction on facial swab samples.

The researchers found that patients who received E-BPO first experienced a reduction in the relative abundance of Staphylococcus and an increase in Cutibacterium from baseline to week 8. In terms of species, this group had an increased abundance of C. acnes and a decreased abundance of S. epidermidis at 8 weeks, which these levels remaining unchanged after the group crossed over to vehicle cream treatment.

Researchers observed no notable changes in bacteria genus or species in the group that received vehicle cream first at week 8.

Additionally, participants in both groups showed similar bacterial diversity profiles based on the Shannon diversity index.

The E-BPO group achieved significantly improved sebum levels from baseline to week 8 (31.68 µg/cm²; P = .011), whereas the vehicle cream group saw a reduction (–2.15 µg/cm²), representing a significant difference between groups (P = .0087).

Compared with the vehicle cream group, a greater proportion of the E-BPO group achieved a “clear”/”almost clear” IGA score (78.57% vs. 37.5%), no/mild facial erythema (85.71% vs. 43.75%) and no/mild inflammation (92.86% vs. 37.5%) at week 8.

Researchers noted that patients who crossed over from vehicle cream to E-BPO demonstrated similar improvements from weeks 8 to 12.

Additionally, all adverse effects were considered mild or moderate and only one out of four adverse effects that occurred among patients treated with E-BPO — a case of contact dermatitis — was deigned treatment-related. Researchers credited the microencapsulation of the treatment for its safety profile, as it’s been noted that unencapsulated BPO often is poorly tolerated.

The researchers identified several limitations to this study, including its small population size and the use of only surface swabs for microbiome sampling.

Overall, the researchers noted their results suggest that a decrease in the abundance of S. epidermidis correlated with an improvement in rosacea, although further mechanistic analyses are needed to evaluate how S. epidermidis functions in relation to the disease.

“Overall, the bacterial diversity did not significantly change, suggesting that more than diversity alone may be needed to assess the microbiome. Individual changes in species quantity may be more important than overall diversity shifts in rosacea,” Nong and colleagues wrote.

They concluded that E-BPO may encourage a shift toward a more balanced cutaneous microbiome, which helps to alleviate rosacea symptoms. Future research should evaluate the follicular microbiome in rosacea and use larger populations to confirm these results, the researchers wrote.