We all know that depression can be caused by life events; but it is possible that may be different from the depression that is caused by underlying physical abnormalities of the brain, abnormalities such as neuroinflammation.
Or it may be that people who experience depression from life events may be predisposed to doing so, by having latent abnormalities of the brain that manifest into depression in times of adverse life events.
I think the article also references the claim that trauma/ psychological distress can trigger immune activation. Which, if you accept, means the depression is driven by inflammation hypothesis holds up whether attributed to biological factors like infection, or psychological. This all makes it quite complicated figuring out what is going on and where it is most efficacious to intervene, but trials of anti-inflammatory agents seem reasonable.
I thought the article was an interesting read but muddled in places. I'm not sure that chest pain due to anxiety (panic attack?) involves the immune system, rather the ANS. At one point I thought the author was going suggest it possible to manifest fatal levels of TNF, just by having bad thoughts.