Increased seum levels of IL-22 in patients with nickel contact dermatitis

Nickel can elicit both Th1-type and
Th2-type responses in vitro in
patients with nickel allergic contact
dermatitis, but this complex cytokine
cascade has still to be clarified. The
recently discovered Th17 subset,
which has crucial functions in host
defence against infections and has
been implicated in the development
of autoimmune diseases, has been
supposed to play an important role
in some inflammatory and autoimmune
skin disorders,
Among TH17 cytokines, IL-22,
has been demonstrated to have a crucial
function in the development of
dermal inflammation and epidermal
acanthosis induced by IL-23 in mice.
We measured the circulating
levels of this cytokine in 31 patients
with allergic nickel contact dermatitis and in
15 controls.
IL-22 serum levels were significantly
higher in patients affected by
contact dermatitis compared with
controls.
It has been demonstrated
that the injection of IL-23
(a Th17-inducing cytokine) into mice
ears induces a model of psoriasis-like
lesions mediated by IL-17 and
IL-22. However,
the histological features found in these
murine models are not exclusively
characteristic of psoriasis but of allergic
contact dermatitis as well.
Our data suggest a possible involvement
of IL-22 in the pathogenesis of
human allergic contact dermatitis.
Therefore, as hypothesized for psoriasis,
IL-22 could be of potential interest
as a therapeutic target for the
treatment of the disease.