Is depression an inflammatory disease? In the paper:


Michael Berk et al, So depression is an inflammatory disease, but where does the inflammation come from?, BMC Medicine 2013, 11:200, doi:10.1186/1741-7015-11-200


it is presented as an undisputed fact that depression is an inflammatory disease.

For example (the first sentence of the abstract):


  We now know that depression is associated with a chronic, low-grade inflammatory response and activation of cell-mediated immunity, as well as activation of the compensatory anti-inflammatory reflex system.


However, AFAIK, we are far from understanding the etiology of depression (perhaps there is no universal one). Sure, there are many correlates (for example – levels of neurotransmitters), but I haven't heard  that there a single, accepted cause (except for the cited paper). For the reference, Wikipedia mentions inflammation as one of multiple related conditions in the "Other hypotheses" section. 

So, as of now, is it universally accepted that depression is an inflammatory disease?
And if not, is it at least one of many mainstream opinions?

Discussion on HN, through which I've learnt about this paper
There certainly isn't a single cause of depression. Wikipedia does not list inflammation, so that seems to be sufficient disproof of universal acceptance, and at least one candidate for representative of mainstream opinions. Berk and colleagues (2013) make a pretty convincing case though, so it may only be a matter of time, exposure to the evidence, and someone bothering to update Wikipedia.

For another, partially independent (probably cites some of the same studies), preexisting reference on the matter, check out Psychology Today's article, "The Brain on Fire: Inflammation and Depression: Inflammation and Its Effects on Mood" (Greenblatt, 2011, November 23). It too supports the potentially causal relationship, though I don't see any direct evidence of inflammation causing depression here. You may want to scrutinize it more closely than I have; if you find anything, please comment or edit!