Intestinal bacteria linked to psoriasis

This article is written by Edward Alain Pajarillo, MSc, Ph.D. Research Associate @ Florida A&M University.

Recently, a friend of mine consulted about a condition known as psoriasis. And since no medical doctor could help her in her long-lasting condition (at least at the moment), I tried to help her through my expertise. As a gut microbiologist, I am interested in the link of various diseases with what is inside us. Personally, I believe in the saying that says “What you eat is what you are” or “Garbage In, Garbage Out“.

psoriasis-neckPsoriasis is an autoimmune disease characterized by red, itchy and scaly patches. Although psoriasis is relatively less damaging, long-term effects could lead and be associated with other serious diseases. The cause of psoriasis is not fully understood, several theories suggest it could be genetic, lifestyle, human immunodeficiency virus (HIV) infection, microbiota- or drug-induced. What if the doctor could not determine the cause or the cure for your psoriasis? That is why it is important to explore other possibilities that could be linked to such ailments. Now, let’s look into an unconventional cause for psoriasis – the gut microbiome.

In a study published last year, scientists investigated the composition of the gastrointestinal tract of experimental mice in association with psoriasis and immune response. Zákostelská and colleagues analyzed this link by inducing psoriasis to mice using imiquimod. Experimental set-up includes antibiotic-free and antibiotic-treated psoriatic (imiquimod-induced) mice.  The antibiotic treatment contains a mixture of metronidazol, colistin and streptomycin. Analysis for bacterial composition and T helper 17 (Th17) cell were performed. According to their results, antibiotic treatment increased Lactobacillus and reduced Coriobacteria and Clostridia after antibiotic treatment. In addition, Th17 cell, a marker for inflammation, was lower when given the antibiotic. Overall, antibiotic-treated mice had a lower incidence of psoriasis compared with antibiotic-free mice.

Findings suggest that increasing Lactobacillus and decreasing Coribacteria/Clostridia could be associated with decreased inflammation leading to the control of psoriasis. It is interesting to look for which particular species of Lactobacillus, a generally safe and probiotic bacteria. Another direction of this study is which particular harmful bacteria induces psoriasis, and what functional activities are being induced or hindered by these bacteria. Lastly, something to take note, imiquimod-induced psoriasis may not reflect the condition of psoriasis patients, it will only mimic the symptoms of this disease as a model for this experiment.

This article is published by Zákostelská et al., 2016 in the Public Library of Science (PLOS) One “Intestinal microbiota promotes psoriasis-like skin inflammation by enhancing Th17 response”. (



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