Nε-(carboxymethyl)lysine promotes lipid uptake of macrophage via cluster of differentiation 36 and receptor for advanced glycation end products

Figure 1 N^ε-(carboxymethyl)lysine promotes lipid uptake and cluster of differentiation 36 and receptor for advanced glycation end products expression in Raw264. 7 cells. A: Oil Red O staining of lipid accumulation in Raw264.7 cells, Scale 20 μm; B: Oil Red O staining quantification of lipid accumulation in Raw264.7 cells; C-E: Protein levels of cluster of differentiation 36 (CD36) and receptor for advanced glycation end products (RAGE) in Raw264.7 macrophages; F and G: mRNA abundance of Cd36 (F) and RAGE (G) in Raw264.7 macrophages. ^aP < 0.01 compared with control (Ctrl) group. CML: N^ε-(carboxymethyl)lysine.

Figure 2 N^ε-(carboxymethyl)lysine has a higher binding affinity to cluster of differentiation 36 than to receptor for advanced glycation end products. A and B: Detection of N^ε-(carboxymethyl)lysine (CML) binding to cluster of differentiation 36 (CD36) (A) and to receptor for advanced glycation end products (RAGE) (B) by immunoprecipitation; C: Synthesis of N-succinimidyl-4-¹⁸F-fluorobenzoate-CML; D and E: Detection of the specific binding between CML and CD36 (D) and between CML and RAGE (E) with radioreceptor ligand binding assays; F: Molecular docking model of CML-CD36 binding; G: Detail of the binding site of CML to CD36; H: Amino acids for the binding interaction between CML and CD36. SB: Specific binding; NB: Non-specific binding; TB: Total binding. CPM: Counts/minute.

Figure 3 Blockade of cluster of differentiation 36 or receptor for advanced glycation end products inhibits the capture of N^ε-(carboxymethyl)lysine by macrophages. ^bP < 0.05, compared with IgG group. ^cP < 0.05, compared with Anti- cluster of differentiation 36 (CD36) group. ^dP < 0.05, compared with Anti-receptor for advanced glycation end products (RAGE) group. Ctrl: Control; CML: N^ε-(carboxymethyl)lysine; malBSA: maleylated-bovine serum albumin.

Figure 4 Blockade of cluster of differentiation 36 or receptor for advanced glycation end products inhibits the capture of N^ε-(carboxymethyl)lysine by macrophages. ^eP < 0.05, compared with IgG group. ^fP < 0.05, compared with Anti- cluster of differentiation 36 (CD36) group. ^gP < 0.05, compared with Anti-receptor for advanced glycation end products (RAGE) group. Ctrl: Control; CML: N^ε-(carboxymethyl)lysine; malBSA: maleylated-bovine serum albumin.

Figure 5 N^ε-(carboxymethyl)lysine promotes lipid uptake by macrophages through receptor for advanced glycation end products and cluster of differentiation 36. CD36: Cluster of differentiation 36; RAGE: Receptor for advanced glycation end products; CML: N^ε-(carboxymethyl)lysine.