Objective: To investigate the potential role of adipocytes fatty acid binding protein (A-FABP)inhibitor to prevent pancreatic islet cells from cytotoxic injury by inflammatory cytokines released from macrophage.
Methods: Co-culture system for RAW264.7 macrophage and MIN6 insulinoma cells was established through transwell combined with A-FABP inhibitor BMS309403 treatment for 48 h. Meanwhile, cultured RAW264.7 and MIN6 respectively were set up as controls. In the inhibitor group, BMS309403 preprocessing (5 µmol/L) was performed 2 h before co-culture. The expression of toll-like receptors(TLR)4 and A-FABP in RAW264.7 macrophages was detected by RT-PCR and Western blotting, interleukin (IL)-1β and tumor necrosis factor(TNF)-α levels in the supernatant were detected by ELISA, Glucose-stimulated insulin level was detected by insulin radioimmuno-assay kits for the function of islets.
Results: (1) The mRNA and protein levels of both TLR4 and A-FABP in RAW264.7 macrophages as well as the concentrations of IL-1β and TNF-α in the supernatant were significantly higher in co-culture group than in macrophages control group (P < 0.05). (2) Insulin secretion stimulated by high glucose was obviously decreased in co-culture group when compared with insulinoma cells control group [(16.0 ± 2.2) vs (41.1 ± 6.6) ng/ml, P < 0.05]. After the treatment with A-FABP inhibitor, the mRNA and protein levels of both TLR4 and A-FABP as well as the concentrations of IL-1β and TNF-α in the supernatant were significantly lower than in co-culture control (P < 0.05). However, insulin secretion stimulated by high glucose was significantly enhanced when compared with insulinoma cells control group [(31.4 ± 3.3) vs (16.0 ± 2.2) ng/ml, P < 0.05].
Conclusions: This study demonstrated that co-culture of macrophage and islet cells can activate inflammation pathway, stimulate inflammatory cytokine release and decrease insulin secretion from islet cells. A-FABP inhibitor can protect islet cells from macrophage-mediated cytotoxicity and preserve its insulin secretory function.