Antidepressant effects of selective serotonin reuptake inhibitors (SSRIs) are attenuated by antiinflammatory drugs in mice and humans

This study found that frontal cortical levels of certain cytokines (TNF alpha and Interferon gamma ) were increased by antidepressant serotonin reuptake inhibitors and that these effects were inhibited by antiinflammatory agents. Furthermore a retrospective analysis of patient data suggested that this antagonistic effect was also seen in the clinic. i.e. anti-inflammatories block the effects of antidepressants.
The interest is twofold - why do SSRI's increase cytokine levels and - is this in any way relevant to their effects ? and why should blocking inflammation stop antidepressants working ?