Microbiome Modulation in Acne Patients and Clinical Correlations.

Background: The imbalance of skin microbiota in acne can induce changes leading to induction or to aggravation of chronic inflammatory lesions; complex mechanisms are involved. ( ribotypes RT4 and RT5 express more biofilm and are associated with inflammatory acne lesions. RT6 is a non-acne ribotype, beneficial for the skin.

Objectives: In an open clinical trial, acne adults were included and assessed clinically at baseline and at month 2 using the Investigator Global Assessment of Acne (IGA) score. A topical emulsion was applied twice daily for 2 months (M2) in each included patient. In the same series of acne patients, skin swab samples were collected from acne patients at baseline and M2 from lesional and non-lesional skin; skin swabs were collected for the metagenomic long-read analysis of microbiota.

Materials And Methods: Acne patients with a gravity score IGA of >1<3 were included in this pilot study. An emulsion of O/W formulated with vegetal extract of associated with a polysaccharide at 1% was applied twice daily for 2 months. At baseline and M2 clinical assessments were made; skin swab samples were also taken for microbiota analysis from lesional and non-lesional skin in each included patient. Extractions of genomic DNA (gDNA) from swab samples from baseline and from M2 were made, followed by full-length (V1-V9) amplification of the 16S rDNA and sequencing of amplicon libraries for strain-level bacterial community profiling.

Results: In a series of 32 adult acne patients, the mean initial IGA scale was 3.1; at M2 the IGA scale was 1.5 ( < 0.001). The mean decrease in acne lesions was by 63%. Microbiome metagenomic long-read analysis in these series was mainly dominated by followed by (. The density of ribotypes RT6 (non-acne strain) was increased at M2 compared to baseline and the density of ribotypes RT1 to RT5 was decreased at M2, compared to baseline ( < 0.0001). ribotypes (1 to 36) were non significantly increased at M2, compared to baseline ( < 0.1).

Conclusions: In a series of 32 acne patients that applied an emulsion based on vegetal extract of and a polysaccharide at 1% twice daily, a significant clinical improvement in IGA scale for acne lesions was seen at M2, compared to baseline ( < 0.0001). The clinical improvement was correlated with an improvement in skin microbiome at M2 compared to baseline, indicated by the increase in the relative abundance of non-acne strain of ribotype 6 and of the decrease in the relative abundance of acne strains ribotypes RT1 to RT5.