In a particular observational study comparing the gut microbiota composition of 34 monozygotic twin pairs discordant for MS, an increased abundance of A. muciniphila was reported in the untreated twins affected by MS compared with either the healthy twins or those affected by MS who were receiving treatment; FMT from twins with MS induced a significantly higher incidence of disease in transgenic mouse models of spontaneous brain autoimmunity, with IL-10 being involved in preventing disease development [157]. Here, IL10 is linked to myeloid sarcoma.