Grey boxes depict the mechanisms involved on the inhibition of inflammation and autoimmunity by neuropeptides. Black arrow, stimulation. Back-crossed line, inhibition. ▲, increase; ▼, decrease. Treg, regulatory T cells; Tr-1, type 1 Treg; DC, dendritic cells; MΦ, macrophages; NO, nitric oxide; PGE2, prostaglandin E2; PPARγ, peroxisome proliferator-activated receptor-γ; HMGB1, high-mobility group box-1; IL, interleukin; TNF, tumor necrosis factor; IL-1Ra, IL-1 receptor antagonist.