Effect of 1,25(OH)2 D on M1 and M2 phenotype switching. (a) Experimental model of M1 and M2 phenotype switching with hypothesized effects of 1,25(OH)2 D (1,25D) identified with arrows. (b–d) Effects of 1,25(OH)2 D on (b) NOS2 mRNA, (c) Arg1 mRNA, or (d) Arg1/NOS2 mRNA ratio during IL-4–mediated of M1 to M2 phenotype switching. (e–g) Effects of 1,25(OH)2 D on (e) NOS2 mRNA, (f) Arg1 mRNA, or (g) NOS2/Arg1 mRNA ratio during IFNγ + LPS–mediated M2 to M1 phenotype switching. Bars are representative data from one of three replicate experiments are shown (n = 3 replicates in each experiment). Numbers above bars in (b), (e), and (g) are the overall percentage change of the data combined from all three replicates (n = 3 experiments). In (a), (c), and (f), bars with different letter superscripts are significantly different at P < 0.05. In (d), *P < 0.05 versus M1, #P < 0.1 versus M1-M2. In (e) and (g), * P < 0.05 versus vitamin D–treated group). AU, arbitrary units.
