Gut microbiota of psoriasis patients: less diverse and reduced functionality

The microbiota of patients with psoriasis are less diverse compared with healthy controls. Moreover, psoriasis patients show a decreased functional richness compared with both healthy controls and healthy partners that live in the same household.

Advances in technology have led to an increased number of studies investigating the microbiome in patients with inflammatory diseases. Growing evidence supports an altered gut microbiota in patients with psoriasis. Culture-based studies have identified an increased presence of oral Candida in patients with psoriasis [1]. Interestingly, probiotics have been associated with a significant improvement in the severity of psoriasis but did not change microbiota [1]. “There is an association, but, according to our recently published review, the results are quite heterogeneous,” Dr Tanja Todberg (University of Copenhagen, Denmark) explained [1,2]. This can in part be explained by poor study design with most studies lacking relevant inclusion criteria and baseline information [1].

To further assess microbiota in psoriasis, Dr Todberg and colleagues defined 3 different research questions: Do patients with psoriasis exhibit an aberrant gut microbial profile compared with healthy individuals? Do patients with psoriasis exhibit an aberrant gut microbial profile compared with their healthy partners that live in the same house? And is the known seasonal change of psoriasis severity associated with a shift in the composition of the gut microbiota?

The researchers collected 126 faecal samples: 53 from patients with plaque psoriasis without systemic treatment, another 52 from healthy controls matched for age, sex, body mass index (BMI), and geographical location, and 21 of the healthy cohabitants of the psoriasis patients. All participants with psoriasis had to have a Psoriasis Area Severity Index (PASI) score of ≥8, restriction of antibiotics and systemic anti-inflammatory treatment for >3 months, and a BMI <35. Patients with diabetes or other inflammatory conditions were excluded. “We assessed patients with more severe disease to be able to see a difference. There is definitely a correlation between differences in gut microbiota and increasing severity of disease,” Dr Todberg explained.

“Our psoriasis patients had moderate-to-severe disease with early-onset and a normal weight. What separated them from the control group is that they smoked significantly more, and their level of physical activity was significantly lower,” Dr Todberg said. The microbial composition of the patients with psoriasis was characterised by a significantly lower richness (P=0.007) and difference in community composition (P=0.01) of metagenomic species compared with healthy controls. Moreover, the functional richness was decreased in patients with psoriasis compared with healthy controls (P=0.01) and partners (P=0.05). Interestingly, no seasonal differences were detectable in the gut microbiota.

In conclusion, the study showed that patients with psoriasis exhibit a dysbiotic taxonomic and functional gut microbiota compared with age, sex, and BMI-matched healthy controls. Despite the similar environment, a significantly lower microbial diversity was seen in patients with psoriasis compared with their partners (P=0.04). As Dr Todberg commented in the discussion, a pilot study examined the effect of adalimumab on gut microbiota in 10 psoriasis patients. Although the therapy had a very positive impact on the skin lesions, the gut microbiota stayed the same, even after 5–6 months of adalimumab therapy.

1. 
   
   1.  Todberg T, et al. Acta Derm Venereol. 2021;101(7):dv00512.
   
   
   2. Todberg T, et al. Characteristics of the gut microbiota in patients with psoriasis. FC09, Psoriasis from Gene to Clinic 2021, 9–11 December.

 

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Posted on 2 February, 20222 February, 2022