Mucosal administration of alpha-fodrin inhibits experimental Sjögren's syndrome autoimmunity

alpha-Fodrin is an autoantigen in Sjögren's syndrome. We hypothesized that mucosal administration of alpha-fodrin might prevent the disease.

Four-week-old NOD mice were immunized (intranasal) with a 1 microg or 10 microg dose of alpha-fodrin every other day. PBS 10 microl/dose and Glutathione transferase (GST 10 microg/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-alpha-fodrin, and anti-type 3 muscarinic acetylcholine receptor polypeptide (anti-M3RP) by immunofluorescence or ELISA. The cytokines IFNgamma 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-alpha-fodrin and anti-M3RP antibodies was delayed in mice immunized with alpha-fodrin. The titers of anti-alpha-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 alpha-fodrin 1 microg/dose group, and three out of eight mice in the alpha-fodrin 10 microg/dose were positive for antinuclear antibodies. The levels of serum IFNgamma in mice immunized with 1 microg/dose or 10 microg/dose alpha-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 alpha-fodrin groups compared with the PBS and GST control groups (P < 0.05). Lymphocytic infiltration and expression of alpha-fodrin in the salivary glands was decreased in alpha-fodrin-treated groups. The fluid intake of mice in the 1 microg/dose alpha-fodrin, 10 microg/dose alpha-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 alpha-fodrin effectively inhibited the progression of experimental Sjögren's syndrome autoimmunity.