Objective: To investigate the effect of complete Freund's adjuvant (CFA) on islet beta cell apoptosis in preventing diabetes in non-obese diabetic (NOD) mice, and the influence on apoptotic related-gene expression.
Methods: Four-week-old female NOD mice were randomly divided into Group CFA (n=5) and Group saline (NS) control (n=5). Mice in Group CFA were injected in the hind footpad with 50 microL CFA and mice in Group NS with 50 microL NS. Blood sugar was monitored and diabetes was diagnosed if blood sugar was higher than 11.1 mmol/L for 2 continuous days in the NOD mice. The mice were sacrificed when diagnosed as diabetes or at 30 weeks of age. Pancreatic sections were made for: evaluation of insulitis severity with HE staining; counting of apoptotic beta cells with the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL) method, and ABC immunohistochemical double labeling; counting of Fas, FasL and Bcl-x positive cells respectively with ABC immunohistochemical method.
Results: By 30 weeks of age, none of the 5 CFA-treated mice, compared with 3 of the 5 control mice, had developed diabetes. The insulitis score was lower (1.820+/-0.962 vs. 3.020+/-1.040, P<0.05), the rates of apoptotic beta cells, Fas positive cells and FasL positive cells were lower [(10.2+/-2.8)% vs. (15.9+/-6.5)%, (54.9+/-14.5)% vs. (75.7+/-12.9)%, (20.3+/-10.4)% vs. (27.9+/-12.0)%, P<0.05), and the Bcl-x positive cell rate was higher [(74.9+/-10.7)% vs. (66.0+/-18.3)%, P<0.05] in the CFA-treated group than those in the NS-treated group respectively.
Conclusion: CFA may inhibit beta cell apoptosis in NOD mice by regulating Fas, FasL and Bcl-x expression on cells within islets.