Multiomic Analysis of the Gut Microbiome in Psoriasis Reveals Distinct Host‒Microbe AssociationsOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This pilot study examined the systemic, gut-based component of psoriasis by combining several data types from the same people. The goal was to link gut microbes to host immune biology and to psoriasis comorbidity risk. Investigators ran shotgun metagenomic sequencing of stool for microbial taxa, gene families, and pathways. They added RNA sequencing of sigmoid colon biopsies and flow cytometry of blood immune cells. They then built multiomic correlation networks integrating microbial and host features. Differential abundance used DESeq2 with adjustment for sex, age, and batch.
Who was studied?
The cohort was 33 adults with psoriasis not on systemic therapy and 15 age- and sex-matched healthy controls, recruited in the San Francisco Bay Area of the United States. Psoriasis patients had a mean PASI of 14.2, indicating moderate-to-severe disease, and all had a normal-appearing lower endoscopy. Patients on recent biologics, systemic drugs, or antibiotics were excluded. Stool went to metagenomics (48 samples), while 42 subjects also provided colon biopsies and blood. A 40-subject subset with complete data (26 psoriasis, 14 healthy) entered the integrated multiomic analysis.
What were the most important findings?
Psoriasis gut microbiomes showed higher microbial functional diversity, though overall taxonomic diversity and community structure looked similar to healthy controls. Clustering of microbial gene families revealed three subgroups. Two were almost entirely psoriasis patients (nine each), and each subgroup carried distinct microbial pathways and immune profiles despite similar disease severity. Some subgroup signatures resembled inflammatory bowel disease or psoriatic arthritis. Notably, all patients in the PSO3 subgroup reported joint pain or swelling. Certain microbial pathways correlated with circulating IL-17 production only in psoriasis.
What are the greatest implications of this study?
The results argue that psoriasis is biologically heterogeneous and that host-microbe interactions may be context dependent, differing by patient subgroup rather than following a single pattern. Subgroups that mirror IBD or psoriatic arthritis signatures hint that microbial and immune profiling could one day help stratify which patients are at risk for specific comorbidities. The authors stress this is a small pilot needing validation in a larger, ideally longitudinal cohort. The associations are correlational and do not establish that microbes cause psoriasis or its comorbidities.