We can take it one step further: There are microbes everywhere in your body, they matter and they do things. When you take them away or fuck with them too much, weird things start happening.
It is I think not a particularly surprising take. But then often it can be valuable to have things that are kind of obvious codified into a paper of some sort so that we no longer have to rely on "but isn't that obvious?" and can instead point to some primary source that actually explains what is true. That way it can be true for everyone, even the people for whom it wasn't already obvious.
The immune systems does nothing by accident. The immune system is always trying to keep the microbiome in balance and the microbiome helps the immune system as well.
Varying intestinal permeability has usually been related to inert compounds. More recently there has been some study on the significance of certain microbe metabolites, but the evidence for any kind of large scale microbial translocation in people that are not very sick (ie septic) is extremely tenuous.
"Key controversies in blood microbiome research are the susceptibility of low-biomass samples to exogenous contamination and undetermined microbial viability from NGS-based microbial profiling"
Just because you can amplify some sporadic bacteria DNA from the blood does not mean that bacteria are hanging out in the blood in a physiologically meaningful way.
A lot of it is frankly junk science in disreputable journals.
It is I think not a particularly surprising take. But then often it can be valuable to have things that are kind of obvious codified into a paper of some sort so that we no longer have to rely on "but isn't that obvious?" and can instead point to some primary source that actually explains what is true. That way it can be true for everyone, even the people for whom it wasn't already obvious.