The microbiome of the “sterile” pustules in palmoplantar pustulosis

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.

Molecular detection of fungal and bacterial DNA from pustules in patients with palmoplantar pustulosis: special focus on Malassezia species

“…To determine if bacteria were present in the PPP pustules, we used the 16S small subunit ribosomal gene . We found no bacterial DNA in the pustules, contrary to the report of Masuda‐Kuroki et al . We used the primer set for a full‐length sequence of the nine specific regions (V1–V9) due to the accurate taxonomic classification, whereas Masuda‐Kuroki et al .…”

“…used primers specific to the V1–V2 region, which can yield a positive result. In addition, Masuda‐Kuroki et al . reported that bacterial DNA fragments were detected in the vesicular fluid but not in the pustular fluid.…”

Palmoplantar pustulosis emerged on a case of generalized pustular psoriasis successfully treated by secukinumab

“…As far as we know, only six children with TMEP have been reported. 1 We herein report a child with TMEP with characteristic linear distribution following Blaschko lines.…”

“…2 Levels of both IL-23 and Th17-derived cytokines, such as IL-17 and IL-22, are upregulated in PPP lesions, suggesting a similar Th17-mediated cytokine circumstance to psoriasis. 1 However, secukinumab, an IL-17A inhibitor, did not show the effectiveness against PPP, in contrast to the excellent effect on psoriasis. 3 In the present case, the GPP lesions had completely been remitted by secukinumab therapy, but not PPP lesions.…”

“…Acrosyringium is supposed to be a main inflammatory site of PPP, and vesicles/pustules converted from vesicles (pustulovesicles) limited on palms and soles can be a representative feature of the lesions. 1 The recent advance of research and molecule-targeted therapy elucidate the similar but distinct molecular mechanism.…”