ROME – Patients with systemic sclerosis have a distinct colonic microbiota, compared with healthy individuals, which could contribute to their immune dysfunction and symptoms, according to a new study.
As with chronic inflammatory states such as inflammatory bowel disease, systemic sclerosis (SSc) patients had decreased commensal gut bacteria such as Bacteroides and Faecalibacterium, and increased pathogenic genera such as Enterobacteriales and Fusobacterium, in the cecum and sigmoid, compared with healthy controls.
Dr. Elizabeth Volkmann
In addition, SSc patients had increased sigmoid and cecum Bifidobacterium, which is typically found in lower abundance in inflammatory bowel disease. Additional taxa alterations also were observed. These differences had never been described in scleroderma before, according to lead study author Dr. Elizabeth Volkmann, a rheumatologist and clinical instructor at the University of California, Los Angeles.
“Gastrointestinal tract dysfunction affects 90% of systemic sclerosis patients and is a leading cause of morbidity and mortality in these patients,” Dr. Volkmann said in an interview. “Symptoms such as constipation and fecal incontinence are among the most disruptive physical problems for SSc patients, and we really don’t know the cause of them at this point.”
Dr. Volkmann and her colleagues studied 17 patients with SSc: Eighty-eight percent were women, the median age was 52 years, and the median disease duration was nearly 7 years. They compared these patients to age- and gender-matched healthy controls. The SSc patients had a mean total score of 0.7 on the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract (UCLA SCTC GIT) 2.0 questionnaire, indicating moderate symptom severity.
At baseline, the patients underwent a colonoscopy. Researchers obtained cecum and sigmoid mucosal lavage samples for analysis; they used 16S sequencing to determine the microbiota and the Greengenes database to determine operational taxonomic units, in addition to other tests. Patients also completed the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract (UCLA SCTC GIT) 2.0 questionnaire to assess gastrointestinal symptom severity at the time of colonoscopy, she said at the European Congress of Rheumatology.
“We found significant and profound differences in the microbial composition” between SSc patients and controls, Dr. Volkmann said. “Even with our small sample size, there were still statistically significant differences, including [in SSc patients] a decrease in normal, healthy bacteria and an increase in more pathogenic bacteria that in other disease states cause inflammation.”
Comparisons between SSc patients and healthy controls demonstrated numerous differences in the microbial communities in both the cecum and sigmoid, including a much higher abundance of the species Erwinia and Trabulsiella in patients with the most severe symptoms.
“This suggests not only are there differences in the microbiota composition between SSc patients and healthy controls, but these differences may contribute to clinical symptoms,” Dr. Volkmann said.
The SSc patients had a mean total score of 0.7 on the GIT 2.0, indicating moderate symptom severity. They also had moderate severity on the distension, constipation, emotional well-being, and social functioning domains on the GIT 2.0, and mild symptom severity on the diarrhea and fecal soilage domains.
Replacing healthy bacteria through probiotic supplements may be a potential therapy, she said. However, some SSc patients had an increase in Lactobacillus and Bifidobacterium, which normally are decreased in patients with inflammation, she said. Probiotic therapy should be used to target only species that are decreased, and many commercial probiotics are rich in Lactobacillus and Bifidobacterium.
One potential hypothesis for why some SSc patients had higher levels of Lactobacillus and Bifidobacterium may be because most were using a probiotic, she said. However, they asked patients to stop using a probiotic 3 weeks before their colonoscopy.
Her group is continuing studies in this population to evaluate microbiome changes over the course of a year.
Dr. Volkmann did not report any relevant financial disclosures.