Figure 6. Macrophage-expressed FABP4 contributes to the development of insulitis and diabetes in NOD mice.

Two-week-old female FABP4^+/+NOD mice and FABP4^–/–NOD mice were intravenously injected with GdCl₃ (1 mg/kg) or saline every 3 days (i.v.) for 6 weeks. Diabetes incidence was monitored in the following 30 weeks. (A) Infiltration and (B) quantification of F4/80⁺ macrophages among CD45⁺ cells in islets of NOD mice treated with GdCl₃ or vehicle for 6 weeks (n = 5). (C) Diabetes incidence in FABP4^+/+NOD mice and FABP4^–/–NOD mice treated with GdCl₃ or vehicle. Diabetes incidence was diagrammed with the Kaplan-Meier method, and incidences between different groups were compared with the log-rank test (n = 18 in each group). (D) Glucose tolerance test of 14-week-old FABP4^+/+NOD and FABP4^–/–NOD mice treated with GdCl3 and vehicle control. (E) The quantification of area under curve of different groups (n = 5). (F) Insulitis scores determined by histological evaluation of pancreatic sections as in Figure 4B (n = 6). (G) Quantification of TUNEL-positive β cells in islets of 10-week-old FABP4^+/+NOD mice and FABP4^–/–NOD mice (n = 5). (H) Cleaved caspase-3 activity in pancreatic lysate of FABP4^+/+NOD mice and FABP4^–/–NOD mice treated with GdCl₃ or vehicle for 6 weeks measured by Caspase-3 Fluorometric Assay Kit (BioVision, Inc.) (n = 5). (I) Quantification of the absolute number of CD8⁺ T cells in total T cells (CD3⁺) from islets of above mice (n = 5). (J) Quantification of the absolute numbers of Th1 (IFN-γ⁺CD4⁺), Th2 (IL-4⁺CD4⁺), Th17 (IL-17⁺CD4⁺), and Treg (Foxp3⁺CD4⁺) cells in total helper T cells (CD4⁺CD3⁺) from islets of above mice (n = 5). (K) The relative mRNA abundance of inflammatory cytokines (IFNγ, TNFα, IL1β, and MCP1) in macrophages sorted from the pancreases of above mice treated with GdCl₃ or vehicle (n = 6). Data are expressed as mean ± standard deviation. Statistical significance was determined by 1-way analysis of variance or Student’s t test. *P < 0.05, **P < 0.01, ***P < 0.001.