Per my wife (an actual microbiologist with her undergrad focusing on immunology - providing this as context for why she I asked her, not just an appeal to authority) the core mechanisms are not new, quoting verbatim from messages:

    That’s actually not new science 

    That’s antibody / mhc molecule immuno treatment 

    In cell lines and just started in mice 

So this sounds like what they've done is found a set of molecules/receptors/something that are responsible for the MS and chrohns auto immune disorders that don't take out other things.

This doesn't mean this isn't a major development - MS especially is an awful condition - just the underlying mechanism isn't itself new.