Sterile faecal filtrate transplantation alters phage-microbe dynamics in individuals with metabolic syndrome
Bacteriophages  (phages)  are bacterial viruses thathave  been  shown  to  shape  microbial communities. Previous studies have shown that faecal virome transplantation can decrease weight gain and normalize blood glucose tolerance in diet-induced obese mice. Therefore,we performed a double-blind, randomised, placebo-controlled pilot study in which  individuals with  MetSyn  were  randomised  to  receive  a  faecal  filtrate  transplantation (FFT) from  a  lean healthy  donor  or  a  placebo.  From  baseline  up  to   days,  we  assessed  safety,  effects  on glucose metabolism, and longitudinal changes within the bacteriome and phageome. The FFT was  well-tolerated  and  safe,  and glucose  variability  (time  between  3.9-10  mmol/L  glucose) improved in the week following the FFT.The phage virion composition was significantly altered two  days  after  FFT  as  compared  to  placebo,  which  coincided  with  more  virulent  phage-microbe  interactions. In  conclusion,  we provide  evidencethat  gut  phages  can  be  safely administered to transiently alter the gut microbiota of recipients.