Healthy centenarians show high levels of circulating interleukin-22 (IL-22).

Aging is characterized by a progressive alteration of homeostatic mechanisms modulated by
environmental and genetic factors. It is associated with a pro-inflammatory status. In centenarians,
an increase of pro-inflammatory cytokine production balanced by anti-inflammatory immune response
that would promote longevity is observed. Cytokine dysregulation is believed to play a key role in the
proposed remodeling of the immune-inflammatory responses accompanying old age. IL-22 is a proinflammatory
cytokine belonging to the IL-10 family and represents an important effector molecule of
activated T helper (Th)-22, Th-1, and Th-17 cells. We recruited 17 healthy centenarians (4 males, 13
females, range 100–105 years). All ultralongeval subjects were living at home or in a nursing home.
Sixteen healthy, sex-matched individuals (4 males, 12 females, range 60–95 years) were also recruited as
controls. Centenarians displayed significantly higher circulating IL-22 levels compared to control
population (45.7 66.9 pg/ml versus 11.1 6.5 pg/ml; p = 0.031). It’s well known that IL-22 is a proinflammatory
cytokine produced by activated T lymphocytes and NK cells. IL-22 stimulates the production of
acute phase reactants and promotes the antimicrobial defense. The results of the present study show, for the
first time, that there is an increase of IL-22 in healthy centenarians. This pro-inflammatory condition
probably is protective against infection, promoting the longevity of these subjects.