Figure 5. FABP4 deficiency reduces diabetogenic T cells and inflammatory macrophages in pancreatic islets of NOD mice.

(A) Representative FACS plots showing the frequencies of cytotoxic T cells and helper T cells in total T cells from islets of 10-week-old FABP4^+/+NOD and FABP4^–/–NOD mice. (B) Quantification of the absolute numbers of cytotoxic T cells and helper T cells in total T cells from islets (n = 5). (C) Quantification of the absolute numbers of Th1, Th2, Th17, and Treg cells in helper T cells from islets (n = 5). (D) Quantification of the absolute number of IFN-γ, perforin, and granzyme B in cytotoxic T cells from islets (n = 5). (E) Representative images of IHC staining of macrophages (F4/80⁺, green; DAPI, blue) in islets of 4-week-old and 6-week-old FABP4^+/+NOD and FABP4^–/–NOD mice. Scale bar: 20 μm, with original magnification of 400× (n = 6). (F) Infiltration of macrophage (MΦ) among CD45⁺cells in islets of 4-week-old and 6-week-old FABP4^+/+NOD and FABP4^–/–NOD mice. (G) Quantification of absolute number of macrophages (MΦ) among CD45⁺ cells from islets (n = 6). (H) Representative FACS plots showing the absolute number of M1 and M2 macrophages from islets in 4-week-old and 6-week-old FABP4^+/+NOD and FABP4^–/–NOD mice. (I and J) The quantification of the absolute number of (I) M1 or (J) M2 macrophages in total macrophages from islets (n = 6). (K) The relative mRNA abundance of inflammatory cytokines in macrophages sorted from the pancreases of mice (n = 6). (L and M) Bone marrow–derived macrophages from FABP4^+/+NOD or FABP4^–/–NOD mice were treated with LPS (10 ng/mL) + IFN-γ (100 ng/mL) to induce M1 polarization or IL-4 (10 ng/mL) to induce M2 polarization. The mRNA abundance of (L) iNOS or (M) arginase was determined by real-time PCR analysis (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.