Several research groups have confirmed that in the pathogenesis of the chronic inflammatory
skin disorder rosacea, the composition of the skin and fecal microbiome of affected
patients differs from that of healthy individuals. We studied the stool, blood and
skin microbiomes of rosacea and control patients using 16S rRNA sequencing. Our goals
were to determine 1. whether the microbiome characteristics of rosacea patients differ
from that of healthy individuals, 2. whether the change experienced on the skin can
be confirmed by alterations in the stool microbiome through the mediation of the blood
and 3. whether the metabolic activity of the changed skin, blood or fecal microbiome
can play a role in the pathogenesis of rosacea. The rosacea skin microbiome differed
significantly from the healthy skin microbiome in both alpha and beta diversity, as
well as in the abundance of the genera. Only a few genera abundances differed significantly
in stool and blood samples. The most significant representatives of the rosacea skin
microbiome, Staphylococcus, Cutibacterium, Corynebacterium and Neisseria, cannot be
derived from the feces or blood. The metabolic pathways associated with healthy fecal
microbiome contributed to the production of anti-inflammatory short-chain fatty acids.
While the increased production of adenosylcobalamin, L-isoleucine and thiazole by
the microbiome of healthy skin appeared to have a protective effect, the excessive
heme and H2S production experienced in rosacea skin likely contribute to the deterioration
of the pathology.
