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The microbiome of the "sterile" pustules in palmoplantar pustulosis
Kana Masuda-Kuroki1, Masamoto Murakami1, Naohito Tokunaga2
1Department of Dermatology, Ehime University Graduate School of Medicine, Shitsukawa, Toon City, Ehime, Japan.
Abstract:
The skin microbiome influences skin pathophysiology. Palmoplantar pustulosis (PPP) is a chronic skin disease characterized by infectious-like pustules on the palms and soles. These pustules are thought to be sterile because bacterial cultures obtained from the pustules are negative. However, culture methods are limited in their ability to identify all bacteria on the skin. We hypothesized that the "sterile" pustules of PPP do not lack bacteria, but rather contain a microbiome. To test this hypothesis, we identified bacteria in "sterile" pustules using non-culture methods. We conducted Sanger and 16S rRNA sequencing using primers specific to the V1-V2 region in PPP-pustulovesicles (PVs) (n = 43) and pompholyx vesicle fluids (n = 15). Sanger sequencing identified some Staphylococcus, Propionibacterium, Streptococcus and Pyrinomonas species in PPP-PVs but failed to identify any bacteria in most of the pompholyx vesicles. 16S rRNA sequencing of PPP-PVs indicated the presence of a microbiome that included various phyla, including Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. At the genus level, smokers had higher levels of Staphylococcus in PPP-PVs compared with non-smokers. These results indicate that a microbiome exists in "sterile" pustules of PPP and that PPP smokers had higher levels of Staphylococcus in pustules. It is therefore necessary to reconsider the pathogenesis of PPP from the perspective of the microbiome.
Insights
The skin microbiome plays a role in palmoplantar pustulosis (PPP). This study found a distinct bacterial microbiome within PPP pustules, challenging the notion that they are sterile and suggesting a role for the skin microbiome in PPP pathogenesis.
Area of Science:
- Dermatology
- Microbiology
- Genomics
Background:
- Palmoplantar pustulosis (PPP) is a chronic skin condition with pustules on the palms and soles.
- These pustules are traditionally considered sterile due to negative bacterial cultures.
- Limitations of culture methods may obscure the presence of a skin microbiome in PPP lesions.
Purpose of the Study:
- To investigate the presence of a bacterial microbiome in the "sterile" pustules of palmoplantar pustulosis (PPP).
- To compare bacterial identification in PPP pustulovesicles (PVs) and pompholyx vesicle fluids using non-culture methods.
- To explore potential differences in the PPP microbiome related to smoking status.
Main Methods:
- Utilized Sanger sequencing and 16S rRNA sequencing for bacterial identification in PPP-PVs (n=43) and pompholyx vesicles (n=15).
- Employed V1-V2 region-specific primers for comprehensive bacterial detection.
- Analyzed bacterial phyla and genera, including genus-level comparisons between smokers and non-smokers.
Main Results:
- Sanger sequencing detected some bacteria (Staphylococcus, Propionibacterium, Streptococcus, Pyrinomonas) in PPP-PVs but was largely negative for pompholyx vesicles.
- 16S rRNA sequencing revealed a diverse microbiome in PPP-PVs, encompassing Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes.
- Higher levels of Staphylococcus were observed in the pustules of PPP patients who smoked compared to non-smokers.
Conclusions:
- The "sterile" pustules in palmoplantar pustulosis harbor a complex bacterial microbiome.
- Bacterial culture methods are insufficient for fully characterizing the skin microbiome in PPP.
- The findings necessitate a re-evaluation of PPP pathogenesis, incorporating the role of the skin microbiome, with potential implications for smoking-related bacterial differences.