SAT0363 DELPHINIDIN DOSE-DEPENDENTLY DIMINISHES PERIPHERAL IL-17 AND IFN-Γ PRODUCING LYMPHOCYTES IN PSORIATIC ARTHRITIS

Abstract

Background:Delphinidin, a dietary anthocyanidin and powerful anti-oxidant from pigmented fruits and vegetables, has broad anti-inflammatory properties. In a human skin model of psoriasis, delphinidin reduced expression of proliferative and inflammatory markers (1).Objectives:The rationale of our study was to assess whether delphinidin can in vitro suppress IL-17 and IFN-γ production in peripheral blood mononuclear cell (PBMC) subsets from patients with psoriatic arthritis (PsA).Methods:PBMCs were obtained from 24 patients with PsA attending the outpatient clinic of the Department of Rheumatology/clinical Immunology at the University General Hospital of Larissa, Greece. 16 age- and sex-matched healthy volunteers were also included in the study. Delphinidin was supplemented at a concentration ranging from 1 to 50μg/ml, one hour prior to cell stimulation. Cell viability (Annexin V staining) and innate/adaptive lymphocyte subpopulations were assessed by flow cytometry with a panel of fluorochrome-conjugated antibodies against CD56, CD3, CD4 and CD8. Intracellular expression of IL-17 and IFN-γ was measured following PMA/ionomycin stimulation for 5 hours using standard cell permeabilization protocols and monoclonal antibodies against IL-17 and IFN-γResults:Delphinidin at concentration ≥10 μg/ml sharply diminished IL-17-production by CD4(+) T cells (Th17) and CD56(+)CD3(+) (NKT) cells from patients with psoriatic arthritis and normal controls (p≤0.05). IFN-γ producing T (CD4 and CD8) cells, as well as NK and NKT cells were also dose-dependently suppressed following delphinidin pre-incubation in both patients and healthy controls. Inhibition of IFN-γ(+) cells ranged from 27 to 69% and peaked at delphinidin concentration 20-50μg/ml. The inhibitory effect of delphinidin on IL-17 and IFN-γ producing lymphocytes was not due to compromised cell viability, as assessed by annexin V binding.Conclusion:Delphinidin exerts, in a dose-dependent manner, a profound in vitro inhibitory effect on T cell and NKT cell IL-17 and IFN-γ production in PsA, and therefore, it may be used as a dietary immunosuppressant, complementary to standard treatment.