Immunoregulatory role of 1, 25-dihydroxyvitamin D(3)-treated dendritic cells in allergic airway inflammation

Abstract

To explore the mechanism and immunoregulatory role of 1, 25-dihydroxy vitamin D(3) [1, 25 (OH)(2)D(3)]-treated dendritic cells (DCs) in allergic airway inflammation. Mouse bone marrow-derived DCs were treated by 1, 25 (OH)(2)D(3) for 72 h. The expression levels of different Notch ligands: Jagged1, Jagged2, Delta1, Delta3, and Delta4 in these DCs were detected by RT-PCR and Western blotting. Mouse spleen CD4+ T cells were cultured with 1, 25 (OH)(2)D(3)-treated DCs or 1, 25 (OH)(2)D(3)-treated DCs blocked by polyclonal antibody of Jagged1 or Jagged2 (control group) for 48 h. The percentage of CD4+CD25+Foxp3+ T cells in CD4+ T cells was detected by flow cytometry (FCM). Ten mice underwent intraperitoneal injection of ovalbumin (OVA) to be sensitized and then divided into 2 groups to inhale 1, 25 (OH)(2)D(3)-treated DC suspension and PBS-DC suspension respectively for 6 successive days. Then the mice were killed. Bronchoalveolar lavage fluid was obtained to detect the eosinophil count and the levels of interleukin (IL)-4, IL-6, IL-13, and interferon (IFN)-gamma, and pathological examination of lung was conducted. Spleens were taken out to isolate the CD4+ T cells, and immunolabeling and FCM were used to detect the percentage of CD4+CD25+Foxp3+ T cells. The mRNA and protein expression levels of Jagged1 and Jagged2 in the 1, 25 (OH)(2)D(3)-treated DCs were (0.376 +/- 0.029) and (0.786 +/- 0.034), and (0.564 +/- 0.018) and (0.632 +/- 0.026) respectively, all significantly higher than those of the control group [(0.146 +/- 0.032) and (0.124 +/- 0.025), and (0.267 +/- 0.012) and (0.098 +/- 0.012) respectively, all P < 0.01)]. The percentage of CD4+CD25+Foxp3+ T cells in the CD4+ T cells cultured with 1, 25 (OH)(2)D(3)-treated DCs was (22.49% +/- 0.56%), significantly higher than that of the a PBS control group [(6.67% +/- 0.60%), P < 0.01]. The percentage of CD4+CD25+Foxp3+ T cells in CD4+ T cells after cultured with 1, 25 (OH)(2)D(3)-treated DC blocked by polyclonal antibody of Jagged2 was (6.56% +/- 1.89%), significantly lower than that of the un-blocked control group [(20.37% +/- 1.64%), P < 0.01]. The levels of IL-4, IL-5, IL-13, and IFN-gamma, and eosinophil count in the BALF of the 1, 25 (OH)(2)D(3)-treated DC group were (33 +/- 5) pg/ml, (134 +/- 23) pg/ml, (91 +/- 11) pg/ml, and undetectable (< 12.5 pg/ml), and (236 +/- 29) x 10(3)/ml, all significantly lower than those of the PBS-DC group [(55 +/- 7) pg/ml, (332 +/- 49) pg/ml, (152 +/- 19) pg/ml, and (23 +/- 6) pg/ml, and (588 +/- 56) x 10(3)/ml, all P < 0.01]. The percentage of CD4+CD25+Foxp3+ T cells in the spleens of the 1, 25 (OH)(2)D(3)-treated DC group was (14.69% +/- 1.14%), significantly higher than that of the PBS-treated DC group [(2.38% +/- 0.14%, P < 0.01). Treatment of the DCs with 1, 25 (OH)(2)D(3) inhibits the allergic inflammation in the airway, maybe via the induction of CD4+CD25+Foxp3+ regulatory T cells by 1, 25 (OH)(2)D(3)-treated DCs through Jagged2-mediated Notch signal pathway.