Microbial and autoantibody immunogenic repertoires in TIF1? autoantibody positive dermatomyositis

Spyridon Megremis; Thomas Walker; Xiaotong He; James O'Sullivan; William E.R. Ollier; Hector Chinoy; Neil Pendleton; Antony Payton; Lynne Hampson; Ian Hampson; Janine Lamb

The number of enriched NGS reads per distinct microbial species significantly increased in DM P20 (95%CI: 4.83-4.92) compared to DM P10 (95%CI: 4.27-4.36), while no significant difference was observed in HC P20 (95%CI: 4.89-4.98) compared to HC P10 (95%CI: 4.80-4.89) ( Figure 2D ). The number of sequencing reads per unique microbial species did not differ significantly between DM P20 and DM P10 (adjusted p value >0.999), however it significantly decreased in the HC P20 (95%CI: 2.81-3.04) compared to the HC P10 (95%CI: 3.78-3.85) ( Figure 2F ). Overall, the differential effect of increased sample size on the observed microbial exposure between DM and HC suggests there is a higher biological variability in DM than in HC. DM P20 exhibited a significantly higher number of microbial AA epitopes per microbial species compared to the HC P20 ( Figure 2A ) and a higher number of total identified microbial species (832 versus 718). The same difference was observed in both distinct ( Figure 2C ) and unique epitope sequences ( Figure 2E ). Overall, we demonstrate that plasma from anti-TIF1 DM patients contain a higher number of microbial epitopes per species and against a wider microbial repertoire.