Findings presented at today's EADV 2021 Spring Symposium suggest that an imbalance in gut microbiota (dysbiosis), could play a significant role in the progression of inflammatory skin disease, Hidradenitis Suppurativa (HS).

HS is a painful, long-term skin condition, with a chronic and relapsing nature that significantly impacts patients' quality of life. Researchers at Hacettepe University collected faecal samples from 15 patients with HS and 15 age and sex-matched healthy individuals and analysed regions of the bacterial 16S rRNA gene to investigate differences in their gut microbiota. Researchers found that the relative abundance of three genera of bacteria (known collectively as Firmicutes), unclassified Clostridiales, unclassified Firmicutes and Fusicatenibacter in HS patients were significantly lower than that in controls (p = 0.005, p = 0.029, and p = 0.046, respectively).

Reduced amounts of these bacteria are known to disrupt the regulatory balance within the gut and stimulate an inflammatory response. The human gastrointestinal tract is inhabited by a wide variety of bacterial organisms, known collectively as the gut microbiome. Studies have increasingly demonstrated that the gut microbiome and skin are intrinsically connected, offering defence against pathogens in the environment.

This relationship is known as the 'gut-skin axis' and has been linked to many inflammatory and autoimmune skin disorders, such as acne and psoriasis. This connection inspired the researchers to characterise the composition of HS patients' intestinal microbiome, hypothesising that imbalance may play a role in the high inflammatory burden of this condition.

HS is a multifactorial disease caused by both genetic and environmental factors. Obesity and smoking can significantly exacerbate symptoms, and both of these have an impact on the gut microbiome. Dr Neslihan Demirel Ogut, Usak University Training and Research Hospital explains, "Our research provides evidence the gut-skin axis is implicated in the progression of this chronic inflammatory skin disorder. While further evidence is required, our research suggests that dietary alteration and personalised probiotic supplementation might also be beneficial for HS patients, particularly since treatment options are limited for these individuals".

Gut microbiota plays a critical role in human health through the development of the immune response, controlled by specific pathways and the products of metabolism, known as short-chain fatty acids (SCFA). Bacteria in the gut (such as Firmicutes) produce these SCFAs that ensure a balance between immune cells that stimulate or suppress an inflammatory response is maintained. Any disruption to this balance, as demonstrated by the reduced abundance of these organisms in the gut microbiome of HS patients, may induce an unwanted inflammatory response.

Additional research is required to further understand and explain the connections between gut microbiota and excessive inflammatory state in HS patients. "As one of the preliminary studies investigating HS, this pioneering research lays the foundation for future research into the management of this debilitating condition. It is an exciting breakthrough in a topic currently at the forefront of scientific research", says Marie-Aleth Richard, EADV Board Member and Professor at the University Hospital of La Timone, Marseille.