Specialty: Rheumatology

Keywords: ultra-processed food, gut microbiome, systemic sclerosis

Background: Ultra-processed food (UPF) consumption has been associated with both pro-inflammatory changes in the gut microbiota and chronic inflammatory disease. Alterations in the gut microbiota have also been reported in patients with systemic sclerosis (SSc), a complex autoimmune disorder characterized by inflammation and fibrosis across multiple organ systems, including the gastrointestinal (GI) tract. No prior studies have investigated the impact of UPF consumption on the gut microbiome in patients with SSc. 

Objective: Our study aimed to examine the relationship between UPF consumption and the GI microbiota in patients with SSc.

Methods: Adult SSc patients provided stool samples and completed the Diet History Questionnaire II (DHQ-2). Shotgun metagenomics were performed using the Illumina NovaSeq 6000 with a target depth of 20 million 150x2 sequences per sample. Shotgun reads were inputted into MetaPh1An2 for taxonomic identification of species for compositional analysis, and samples were filtered to retain species with at least 10% non-zero counts. 54 items on the DHQ-2 were identified as UPF by the NOVA scale of food classification. UPF intake was calculated as a continuous variable by gram-per-week consumption according to patient reported frequency. General linear models were created to identify differentially abundant species based on UPF consumption, adjusting for BMI, current PPI use, current probiotic use, current or prior immunomodulatory therapy, and presence of small intestinal bacterial overgrowth. The False Discovery Rate (FDR) was used to correct for multiple hypothesis testing.

Results: Of the 69 total SSc patients included, 59 were female (85.5%). Among 257 species analyzed, the abundance of 10 bacterial species was significantly altered based on UPF consumption in study participants. Upon adjusting for aforementioned covariates, 5 bacterial species were significantly associated with UPF consumption [Table 1], including Limosilactobacillus fermentum (Std-beta 0.32; p<0.01) and Faecalicatena fissicatena (Std-beta -0.35; p<0.01). 

Conclusions: SSc patients reporting a higher UPF consumption demonstrated alterations in GI microbial composition even after adjusting for factors known to affect the microbiota of patients with SSc. Future studies are needed to determine whether interventions at lowering UPF consumption may improve outcomes for patients with SSc.