Protective effects of leflunomide on salivary function of submandibular gland in NOD mice

Objective To investigate the therapeutic effects of leflunomide on salivary gland secretion hypofunction in NOD mice with Sjogren′s syndrome. Methods NOD mice were randomly divided into four groups: prevention group, prevention control group, treatment group and treatment control group. Salivary flow rate was measured after pilocarpine stimulation. Changes in the average number and area of infiltrating lesions were compared after hematoxylin and eosin (HE) staining. The percentages of CD3+ T, CD4+ T, CD8+ T, CD44+ CD62L-CD4+ T, CD19+ B and CD138+ B cells in submandibular gland and spleen were detected by flow cytometry. The levels of TNF-α, IL-17A and IL-6 in serum were detected by CBA method. Results The salivary flow rate (t=-5.81, P<0.001; t=-3.61, P<0.05), the number of infiltrating lesions(t=3.95, P<0.01; t=4.94, P<0.001)and the average area of infiltrating lesions(t=3.18, P<0.05; t=2.35, P<0.05)were significantly ameliorated in the prevention and treatment groups. Moreover, CD3+ CD4+ T cells(t=2.39, P<0.05; t=3.82, P<0.01)and CD44+ CD62L-CD4+ T cells(t=3.53, P<0.05; t=3.36, P<0.05)in the submandibular gland were significantly decreased. CD3+ T(t=6.08, P<0.001; t=2.76, P<0.05), CD3+ CD4+ T (t=3.73, P<0.05; t=2.39, P<0.05), CD19+ B (t=5.88, P<0.001; t=4.23, P<0.01) and CD138+ B cells (t=4.30, P<0.001; t=4.46, P<0.01) in the spleen were also significantly reduced. Serum IL-17A (t=4.15, P<0.01; t=3.36, P<0.01) in the two groups and TNF-α (t=4.56, P<0.001) in the prevention group were down-regulated, but no significant difference was observed in IL-6 level. Conclusions This study suggested that leflunomide could prevent and improve salivary gland hypofunction and inhibit immune activation in NOD mice, providing reference for evaluating leflunomide in the treatment of Sjogren′s syndrome. Key words: Sjogren′s syndrome; Leflunomide; NOD mice; Salivary gland function; Lymphocyte; Inflammatory cytokine