Scientists: Protein IL-17 fights infection, acts on the brain, inducing anxiety

Surprisingly enough, this partially exposes the link between depression and some of the autoimmunal diseases. One example is how patients with psoriasis have significantly elevated levels of proteins from the IL-17 family (namely, IL-17A, IL-17C, and IL-17F) - up to 4 to 8 times above nominal values.

At the same time, bimekizumab, one of the bleeding-edge psoriasis and psoriatic arthritis treatments, suppresses production of IL-17A and IL-17F (methotrexate does that, too, albeit to a much smaller degree). As a result, people receiving IL-17 suppressors become happier over the course of years, and not only due to months-long remission - I had a chance to see this in one of the experimental treatment programs.

Ketamine curbs IL-17 secretion pretty hard. Psoriasis tends to vanish pretty quick after a therapy session.