Splenocytes restore salivary gland function in mice with Sjogren's syndrome

Background: Non-obese diabetic (NOD) mice develop autoimmune diabetes and Sjogren's-like syndrome. Our previous study has shown that injections of spleen cells with Complete Freund's Adjuvant (CFA) reversed diabetes and restored salivary flow rates (SFR) in NOD mice. However, that study did not assess the quality/ composition of the restored saliva and the frequency of SFR measurements were every 6 weeks. Objective: To test whether splenocyte-transplants can restore salivary gland's function (both SFR and composition) in NOD mice. Also this study will monitor more frequently SFR (once every other week as compared to 6 weeks in the previous study). Methods: Female NOD mice were randomized into two groups: Splenocyte-treatment group (N=6) versus control group (N=10; no cell injections, except insulin). Female NOD mice received male CByF1B6F1/J spleen cells. The cell transplants (107 or 106 cells) were either injected through the tail vein (IV) or intraperitoneally (IP). Serum Glucose levels were measured weekly and mice with blood sugar more than 13 mmol/l were labeled as diabetic and treated with daily insulin injection. SFR was determined every other week post splenocyte-treatment. Total protein concentration in saliva was assayed by Bicinchoninic Acid Assay (BCA) method. Results: At 26-week of age, free diabetic survival rate was higher in splenocyte-treated group (66%) than control group (33%). SFR was significantly higher (p<0.05) in treated group (47.73 ml/min/100g BW) when compared to the control group (10.26 ml/min/100g BW). SFR of untreated NOD mice continued to deteriorate over time and all untreated mice died at the end of week 26. Mice in treated group, on the other hand, were alive. Total protein concentration in saliva was lower (P<0.05) in splenocyte-treated group than control group. Conclusion: This study demonstrates that salivary gland function and composition was re-established in NOD mice treated with injections of splenocytes. Study supported by CIHR.