Differences Observed in Gut Microbiomes of Patients with HS Versus Controls

Notable differences have been identified in the gut microbiome compositions of pediatric patients with hidradenitis suppurativa (HS) compared with control participants and adults with HS, new findings suggest, indicating a potential connection to microbiome dysregulation.1

Marianne Collard, PhD—from the Boston University Aram V. Chobanian and Edward Avedisian School of Medicine Department of Dermatology—led the analysis that led to these findings. They noted that prior evaluations of the gut microbiome in those with HS had been conducted.

These prior studies had identified perturbations in gut microbiome compositions compared to matched controls.2 However, this study by Collard et al was carried out with the intention of emphasizing pediatric patients.

“In this follow-up to these studies, we report an analysis of the gut microbiome in 8 patients with HS and 8 matched controls, emphasizing the pediatric population, which has been excluded from previous studies,” Collard and coauthors wrote.1

The investigative team included participants and matched controls, who they aligned based on sex, age, and ethnicity, in this prospective observational analysis. They excluded any potential subjects if they had, in the prior 4 weeks, implemented systemic antibiotics, oral isotretinoin, immunosuppressants, or biologics; had any gastrointestinal conditions; or had a known diagnosis of inflammatory bowel disease or any active gastrointestinal illness.

The investigators gathered fecal specimens, and the V4 region of the 16S rRNA gene was sequenced by the team using the 515F-806R primer set in a polymerase chain reaction protocol. They then followed established protocols for their analysis of the resulting data.

Using Mann-Whitney U tests, Collard et al made statistical comparisons between participants with HS and control subjects, and their results were reported as means and standard deviations. A p-value of less than .05 was considered statistically significant.

The study findings revealed comparable read counts across both study cohorts, and no significant distinctions were noted in β diversity. This, they noted, reflected inter-individual differences in gut microbial communities. This was assessed using unweighted UniFrac and Bray-Curtis principal coordinate analyses.

However, it was also highlighted that a reduction in α diversity—representing within-individual microbial diversity—was also identified in HS participants when measured via Pielou evenness, though other diversity indices did not reflect this change.

In their comparisons of pediatric and adult subjects living with HS, increased abundances of the Ruminococcus and Clostridium genera, along with Bifidobacterium adolescentis, were seen in the pediatric arm of the analysis. Nevertheless, the investigative team noted that no statistically significant differences in α diversity were seen between pediatric and adult patients with HS.

When assessing pediatric patients with HS (n = 4) against pediatric controls (n = 5), the coauthors' principal coordinate analysis showed tighter clustering among the controls, suggesting distinct phylogenetic profiles between the cohorts. While α diversity was not shown to be significantly distinct between children with HS and controls, a trend was shown toward increased representation of the Bacteroidetes phylum in the HS arm.

Additional taxonomic comparison indicated higher levels of an unidentified genus within the Ruminococcaceae family and the Bilophila genus among those in the pediatric HS group. Notably, Faecalibacterium prausnitzii, a species that has been linked to gut health, was also elevated in the pediatric HS group relative to the controls.

Overall, such results echoed the aforementioned earlier results, with Bilophila abundance elevated in HS patients across both pediatric and combined cohort analyses. The investigators highlighted their observation of significant reductions in Pielou evenness α diversity when all trial participants were compared, suggesting potential gut dysbiosis.

In 1 notable observation, B. adolescentis was entirely absent in adults with HS but found in all pediatric patients with HS. Given that the abundance of B. adolescentis typically increases as age increases, its absence in adults may signal a disruption in gut microbiome development. They also noted that bacterium is known to produce γ-aminobutyric acid (GABA), a key neurotransmitter involved in gut-brain communication and connected to anxiety and depressive issues.

“Overall, we found significant differences in gut microbiome composition of pediatric patients with HS compared with pediatric control participants and adult patients with HS, suggesting that gut microbiome dysregulation may extend to pediatric patients with HS and should be investigated further,” they concluded.”1

References

1. Collard M, Grbic N, Mumber H, Wyant WA, Shen L, Alani RM. Gut Microbiome in Adult and Pediatric Patients With Hidradenitis Suppurativa. JAMA Dermatol. Published online May 28, 2025. doi:10.1001/jamadermatol.2025.1318.

2. McCarthy S, Barrett M, Kirthi S, et al. Altered skin and gut microbiome in hidradenitis suppurativa. J Invest Dermatol. 2022;142(2):459-468.e15. doi:10.1016/j.jid.2021.05.036.