α-Fodrin is an autoantigen in Sjögren's syndrome. We hypothesized that mucosal administration of α-fodrin might prevent the disease.
Four-week-old NOD mice were immunized (intranasal) with a 1 μg or 10 μg dose of α-fodrin every other day. PBS 10 μl/dose and Glutathione transferase (GST 10 μg/dose (control mice) were intranasally administrated by the same procedure. The salivary flow was maintained in immunized animals. The animals were analyzed for the presence of anti-Sjögren's syndrome A, anti-Sjögren's syndrome B, rheumatoid factor and antinuclear, anti-α-fodrin, and anti-type 3 muscarinic acetylcholine receptor polypeptide (anti-M3RP) by immunofluorescence or ELISA. The cytokines IFNγ and IL-10 were measured by ELISA. Salivary glands were examined by H&E staining and immunohistochemical analysis. The water-volume intake was calculated for each group. The induction of regulatory T cells was assessed by fluorescence-activated cell sorting analysis for the frequency of Foxp3+ cells among peripheral CD4+CD25+ T cells.
The appearance of anti-α-fodrin and anti-M3RP antibodies was delayed in mice immunized with α-fodrin. The titers of anti-α-fodrin and anti-M3RP antibodies were lower in immunized mice (P < 0.05), but there was no significant difference between the low-dose or high-dose immunization groups. Five out of eight mice in the GST group, five of eight mice in the PBS group, two of eight mice in the α-fodrin 1 μg/dose group, and three out of eight mice in the α-fodrin 10 μg/dose were positive for antinuclear antibodies. The levels of serum IFNγ in mice immunized with 1 μg/dose or 10 μg/dose α-fodrin, with PBS, and with GST were 41.9 ± 16.2 pg/ml, 37.1 ± 15.4 pg/ml, 86.8 ± 17.8 pg/ml and 71.6 ± 11.1 pg/ml, respectively, while we found no difference in the levels of serum IL-10 among the groups. The number of Foxp3+ CD4+CD25+ regulatory T cells was higher in the α-fodrin groups compared with the PBS and GST control groups (P < 0.05). Lymphocytic infiltration and expression of α-fodrin in the salivary glands was decreased in α-fodrin-treated groups. The fluid intake of mice in the 1 μg/dose α-fodrin, 10 μg/dose α-fodrin, PBS, and GST groups was 39.2 ± 2.1 ml, 40.4 ± 2.5 ml, 49.3 ± 3.1 ml and 51.6 ± 2.8 ml, respectively.
Mucosal administration of α-fodrin effectively inhibited the progression of experimental Sjögren's syndrome autoimmunity.