Strain-level immunomodulatory variation of gut bacteria.

The gut microbiota and the immune system have co-evolved to interact and cooperate in many ways. A recent study characterizing the immunomodulatory effects of over 60 different human-derived gut microbes across phyla showed that bacteria-induced immunomodulations are not dictated by the bacterial phylogeny. Yet, it remains unclear whether strains from the same species induce the same immunomodulatory effects on the host. We analyzed the strain-level data from this recent study and found that strains from the same species can induce distinct and sometimes even opposing immunophenotypes. Hence, we suggest that the immunomodulatory capabilities of gut bacteria can be strain-specific.