1 alpha,25-dihydroxyvitamin D-3 induces an autoantigen-specific T-helper 1/T-helper 2 immune shift in NOD mice immunized with GAD65 (p524-543)

Prevention of type 1 diabetes in NOD mice by 1,25-dihydroxyvitamin D-3 [1 a lpha,25(OH)(2)D-3] is accompanied by a T-helper (Th) 1/Th2 cytokine shift i n the pancreas. The aim of this study was to investigate whether this immun e shift also occurs outside of the pancreas and whether it is limited to au toantigen-specific immune responses. NOD mice treated with 1 alpha,25(OH)(2 )D-3 (5 mu g/kg every 2 days) or control vehicle were immunized with GAD65 (p524-543) or ovalbumin (OVA) in the rear footpads. First, we examined T-ce ll proliferation and cytokine production (via enzyme-linked immunosorbent a ssay) of draining lymph node cells in vitro with or without peptide rechall enge. Although no differences in proliferation were measured between contro l and 1 alpha,25(OH)(2)D-3-treated mice after in vitro GAD65 rechallenge, a marked shift in cytokine secretion profile was seen in 1 alpha,25(OH)(2)D- 3-treated mice: interleukin-4 was increased (37 +/- 5 vs. 21 +/- 12 pg/ml i n controls, P < 0.005), whereas gamma-interferon levels were decreased (6 /- 3 vs. 9 +/- 3 ng/ml in controls, P < 0.05). This shift was absent in OVA -primed mice. Second, we measured cytokine profiles by reverse transcriptas e-polymerase chain reaction in popliteal lymph nodes at different time poin ts after priming with GAD65 or OVA in vivo. A marked Th1/Th2 shift occurred in 1 alpha,25(OH)(2)D-3-treated mice after in vivo priming with GAD65. Aga in, this shift was absent after OVA immunization. Finally, we measured cyto kine profiles after rechallenge with a panel of autoantigens (GAD65, heat s hock protein 65, insulin B-chain) and control antigens (OVA, keyhole limpet hemocyanine, myelin proteolipid protein, tetanus toxin) and confirmed the Th1/Th2 shift in autoantigen-injected mice but not in control antigen-injec ted mice. In conclusion, the immune deviation induced by 1 alpha,25(OH)(2)D -3 in NOD mice can also be induced in the peripheral immune system but is l imited to pancreatic autoantigens.