So it is perfectly reasonable to focus attention on people with PEM but I think calling it PENE is a bit imaginative since we do not know what neuroimmune exhaustion would be.
I have never been comfortable with the PENE label/concept. It might be right but I think it is getting a bit ahead of the evidence at this point, and we are in danger of getting lost in the politico-linguistic forest.
Which doesn't mean there are not important neurological and immune features. Just that I don't think we are at the point where we can make definite statements about the nature of PEM, particularly about the causal relationships involved. Though I think we can certainly say it exists, and that understanding it is critical to understanding the whole disease.
From the International Consensus Primer:
The underlying pathophysiology of PENE involves a profound dysfunction of the regulatory control network
within and between the nervous systems
We don't know if this 'dysfunction' starts within those systems/processes, or if it is just the body's attempt to compensate for something else going wrong further back up the causal chain (e.g. via infection, etc). That is, we don't know enough to be sure about PEM's place in the causal chain.
Trying to treat immune parameters directly, for example, might be a dead end if that is not the cause of immune 'dysfunction' and the immune system is actually okay but is just having to deal with something that is pushing it outside its normal operating parameters.
PEM might be just the body's response to adverse circumstances, in the same kind of way that the sick feeling from the flu is from our otherwise healthy body's reaction to the flu virus, not from the virus itself.