Summary Background There is increasing evidence of the key role that the gut microbiota plays in inflammatory diseases. Objectives To identify differences in the faecal microbial composition of patients with psoriasis compared with healthy individuals in order to unravel the microbiota profiling in this autoimmune disease. Methods 16S rRNA gene sequencing and bioinformatic analyses were performed with the total DNA extracted from the faecal microbiota of 19 patients with psoriasis and 20 healthy individuals from the same geographic location. Results Gut microbiota composition of patients with psoriasis displayed a lower diversity and different relative abundance of certain bacterial taxa compared with healthy individuals. Conclusions The gut microbiota profile of patients with psoriasis displayed a clear dysbiosis that can be targeted for microbiome‐based therapeutic approaches. What's already known about this topic? Psoriasis is a chronic inflammatory immune‐mediated skin disease, the aetiology of which remains unclear. The human microbiota is a complex microbial community that inhabits our body and has been related with the maintenance of a healthy status. Several studies have focused on the skin microbiome and its connection with psoriasis although less attention has been focused on the potential role of the gut microbiota in psoriatic disease. What does this study add? This study unravels the gut microbiome dysbiosis present in a cohort of patients with psoriasis, compared with a healthy control group from the same geographical location. This study shows a lower bacterial diversity and different relative abundance of certain bacterial taxa in patients with psoriasis. We gain knowledge and insight into the microbiome alterations in psoriatic disease, opening new avenues for therapeutic approaches to reshape the human microbiome towards a healthy status.

bFor many years, bacterial exopolysaccharides (EPS) have received considerable scientific attention, mainly due to their contribution to biofilm formation and, above all, because EPS are potential virulence factors. In recent times, interest in EPS research has enjoyed a welcome boost thanks to the discovery of their ability to mediate communication processes with their surrounding environment and to their contribution to host health maintenance. In this review, we provide a fresh perspective on the genetics and activity of these polymers in members of the Bifidobacterium genus, a common gut inhabitant of humans and animals that has been associated with several health-promoting effects. Bifidobacteria can use EPS to protect themselves against the harsh conditions of the gastrointestinal tract, thus improving their persistence in the host. Indeed, the relevant function of EPS for bifidobacteria is underlined by the fact that most genomes sequenced until now contain genes related to EPS biosynthesis. A high interspecies variability in the number of genes and structural organization is denoted among species/subspecies; thus, eps clusters in this genus do not display a consensus genetic architecture. Their different G؉C content compared to that of the whole genome suggests that eps genes have been acquired by horizontal transfer. From the host perspective, EPS-producing bifidobacteria are able to trigger both innate and adaptive immune responses, and they are able to modulate the composition and activity of the gut microbiota. Thus, these polymers seem to be critical in understanding the physiology of bifidobacteria and their interaction with the host.