Systemic Sclerosis Patients’ Intestinal Microbiome Found To Be Enriched by Inflammatory Bacteria

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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According to a study recently presented at the Annual European Congress of Rheumatology (EULAR), Rome, patients with systemic sclerosis harbor a unique microbiome in their gut when compared to healthy individuals, which may contribute to patients’ immune dysfunction.

Systemic sclerosis, also known as scleroderma, is an autoimmune disease (autoimmune diseases arise due to an abnormal immune response of the body against substances and tissues normally present in the body) and is characterized by skin thickening — a process known as fibrosis. While in some types of systemic sclerosis skin hardening is confined to head, face and feet, in more severe cases it affects internal organs such as kidneys, heart, lungs and intestine. The disease currently lacks an FDA-approved treatment and is associated with high mortality rates.

In this study, researchers at the University of California, Los Angeles (UCLA) studied the microbial communities (microbiome) present in the gut of 17 patients with systemic sclerosis and compared the microbial identity with those of 17 healthy individuals. The team discovered that systemic sclerosis patients’ microbiomes are enriched by inflammatory bacteria while protective bacteria were reduced, with systemic sclerosis patients exhibiting a microbiota flora similar to patients with Crohn’s disease (a type of inflammatory bowel disease, characterized by chronic inflammation at the digestive tract).

Elizabeth Volkmann, a rheumatologist and clinical instructor at UCLA commented, “Gastrointestinal tract dysfunction affects 90% of systemic sclerosis patients and is a leading cause of morbidity and mortality in these patients. Symptoms such as constipation and fecal incontinence are among the most disruptive physical problems for systemic sclerosis patients, and we really don’t know the cause of them at this point. We found significant and profound differences. Even with our small sample size, there were still statistically significant differences, including [in systemic sclerosis patients] a decrease in normal, healthy bacteria and an increase in more pathogenic bacteria that in other disease states cause inflammation.”

Researchers found an enrichment of bacteria species Erwinia and Trabulsiella in systemic sclerosis patients with the most severe symptoms, suggesting that “not only are there differences in the microbiota composition between systemic sclerosis patients and healthy controls, but these differences may contribute to clinical symptoms,” Dr. Volkmann explained.

Notably, they found that systemic sclerosis patients surprisingly were also enriched in two bacteria species usually found in healthy individuals, Lactobacillus and Bifidobacterium, which are usually reduced in inflammatory diseases patients. As these species are the main component of probiotic diets, which may explain the finding. However, patients were asked to stop taking probiotics before the study.

The team is continuing to study the role of the microbiome in systemic sclerosis in order to understand if the alterations observed are a cause or consequence of the disease. This knowledge will allow design in the future potential new therapeutics against systemic sclerosis.