Photodynamic therapy treats acne by altering the composition of the skin microbiota

Abstract

Background: Acne is the eighth-most prevalent inflammatory skin disease with no optimal treatment. Photodynamic therapy (PDT) is an effective treatment for severe acne.

Aims: The effect of PDT on the composition and diversity of skin microflora in severe acne patients was studied.

Materials and methods: A total of 18 patients with severe acne and 8 healthy individuals were selected for this study. Patients were treated with 5-aminolevulinic acid-mediated PDT once a week three times in total; the skin microbiome was measured by 16S ribosomal RNA gene sequencing before and after treatment (1 week after each PDT).

Results: The microflora composition was different between healthy controls and patients, and between patients before and after treatment. Alpha diversity indices were lower in patients than those in control. There were 15 bacterial genera with high relative abundance that had noticeable changes during treatment. At the genus level,particularly Cutibacterium acnes (C. acnes formerly Propionibacterium acnes), there was no statistically significant difference among different group. The abundances of Staphylococcus epidermidis and Staphylococcus aureus were low.

Discussion: The microbial composition is different between severe acne patients acne patients and healthy individuals. The therapeutic efficacy of severe acne treated with PDT is associated with the composition and diversity of skin microbiota.

Conclusion: The skin microbial composition changes after PDT treatment. PDT is an effective method for the treatment of severe acne.

Keywords: 16S sequencing; Cutibacterium acnes; photodynamic therapy; severe acne; skin microbiota.

FIGURE 1

Taxonomy plot of the microbial communities of all samples at the genus level (X: samples, H [n = 8], healthy control; PTB [n = 18], pre photodynamic therapy group; PTT1 [n = 16], the first photodynamic therapy group; PTT2 [n = 18], the second photodynamic therapy group; PTT3 [n = 12], the third photodynamic therapy group; Y: the relative abundance of bacteria in different samples at the genus level)

FIGURE 2

Heatmap revealed the top 30 skin microflora of patients and healthy individuals in the genus level. The horizontal coordinate is sample; the vertical coordinate is genus. The colors range from red to blue refers that the log10 value of the relative abundance of different isolates in different samples is from 2 to 0. (H group [green], healthy control; PTB group [red], pre photodynamic therapy; PTT1 group [pink], the first photodynamic therapy group; PTT2 group [blue], the second photodynamic therapy group; PTT3 group [yellow], the third photodynamic therapy group)

FIGURE 3

The features of the comparison of microflora between various groups at the genus level (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1 group, the first photodynamic therapy group; PTT2 group, the second photodynamic therapy group; PTT3 group, the third photodynamic therapy group)

FIGURE 4

Microbiota α diversity index (observed OTU [operational taxonomic unit], Chao1, ACE, Shannon, and Simpson indices) in different groups (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1, the first photodynamic therapy group; PTT2, the second photodynamic therapy group; PTT3, the third photodynamic therapy group)

FIGURE 5

Distance heatmap at the genus level. The horizontal and vertical coordinates are the different samples. The colors range from red to blue refers that the Bray–Curtis distance value of different samples is from 0.8 to 0. (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1 group, the first photodynamic therapy group; PTT2 group, the second photodynamic therapy group; PTT3 group, the third photodynamic therapy group)

FIGURE 6

Principal coordinate analysis (PCoA) plots of all skin samples stratified by different groups (H group, healthy control; PTB group, pre photodynamic therapy; PTT1 group, the first photodynamic therapy group; PTT2 group, the second photodynamic therapy group; PTT3 group, the third photodynamic therapy group)

FIGURE 7

UPGMA clustering of skin samples from different groups (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1 group, the first photodynamic therapy group; PTT2 group, the second photodynamic therapy group; PTT3 group, the third photodynamic therapy group)

FIGURE 8

Analysis of similarity (ANOSIM) analysis was used to examine the differences in microbial community composition among these groups at the genus level. (H group, healthy control; PTB group, pre photodynamic therapy; PTT1 group, the first photodynamic therapy group; PTT2 group, the second photodynamic therapy group; PTT3 group, the third photodynamic therapy group)

FIGURE 9

Analysis of similarity (ANOSIM) analysis was used to examine the differences in microbial community composition among different individuals. (X: different individuals, those patients who were not involved in all three treatments were eliminated in this figure.)

FIGURE 10

The taxonomic composition distribution histograms in five groups at the levels of phylum, class, order, family, genus, and species (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1, the first photodynamic therapy group; PTT2, second photodynamic therapy group; PTT3, third photodynamic therapy group)

FIGURE 11

Relative abundance of selected bacterial genera at various groups (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1, the first photodynamic therapy group; PTT2, second photodynamic therapy group; PTT3, third photodynamic therapy group)

FIGURE 12

The change in abundance of Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus between different groups (H group, healthy control; PTB group, pre photodynamic therapy group; PTT1, the first photodynamic therapy group; PTT2, the second photodynamic therapy group; PTT3, the third photodynamic therapy group)