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1,25-Dihydroxyvitamin D₃ Promotes High Glucose-Induced M1 Macrophage Switching to M2 via the VDR-PPARγ Signaling Pathway.

Zhang X, Zhou M, Guo Y, Song Z, Liu B - Biomed Res Int (2015)

Bottom Line: However, the above effects of 1,25-dihydroxyvitamin D3 were abolished when the expression of VDR and PPARγ was inhibited by VDR siRNA and a PPARγ antagonist.In addition, PPARγ was also decreased upon treatment with VDR siRNA.The above results demonstrate that active vitamin D promoted M1 phenotype switching to M2 via the VDR-PPARγ pathway.

View Article: PubMed Central - PubMed

Affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu 210009, China.

ABSTRACT
Macrophages, especially their activation state, are closely related to the progression of diabetic nephropathy. Classically activated macrophages (M1) are proinflammatory effectors, while alternatively activated macrophages (M2) exhibit anti-inflammatory properties. 1,25-Dihydroxyvitamin D3 has renoprotective roles that extend beyond the regulation of mineral metabolism, and PPARγ, a nuclear receptor, is essential for macrophage polarization. The present study investigates the effect of 1,25-dihydroxyvitamin D3 on macrophage activation state and its underlying mechanism in RAW264.7 cells. We find that, under high glucose conditions, RAW264.7 macrophages tend to switch to the M1 phenotype, expressing higher iNOS and proinflammatory cytokines, including TNFα and IL-12. While 1,25-dihydroxyvitamin D3 significantly inhibited M1 activation, it enhanced M2 macrophage activation; namely, it upregulated the expression of MR, Arg-1, and the anti-inflammatory cytokine IL-10 but downregulated the M1 markers. However, the above effects of 1,25-dihydroxyvitamin D3 were abolished when the expression of VDR and PPARγ was inhibited by VDR siRNA and a PPARγ antagonist. In addition, PPARγ was also decreased upon treatment with VDR siRNA. The above results demonstrate that active vitamin D promoted M1 phenotype switching to M2 via the VDR-PPARγ pathway.

No MeSH data available.


Related in: MedlinePlus

The iNOS, MR, VDR, and PPARγ immunofluorescence expression after VDR siRNA intervention (200x).
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fig10: The iNOS, MR, VDR, and PPARγ immunofluorescence expression after VDR siRNA intervention (200x).

Mentions: siRNA targeting VDR was transfected into RAW264.7 cells. A non-target control (NTC) siRNA was used to eliminate the nonspecific effects of the transfection reagents. All three specific VDR siRNAs inhibited VDR expression, but significant differences appeared only with VDR siRNA-1 (0.44 ± 0.05) and VDR siRNA-2 (0.47 ± 0.04) when compared with the control (1.15 ± 0.19) and NTC (1.00 ± 0.00) groups. The inhibition ratios of VDR siRNA-1, 2, and 3 were 56%, 53.5%, and 29.0%, respectively, so we used VDR siRNA-1 as the final intervention siRNA. NTC siRNA clearly showed no effect on VDR expression (Figure 8). As shown in Figure 9(a), depletion of VDR blocked the 1,25(OH)2D3-mediated increase in MR mRNA (VD versus VDR siRNA: 2.63 ± 0.61 versus 1.41 ± 0.44) and decrease in iNOS mRNA expression (VD versus VDR siRNA: 0.91 ± 0.07 versus 1.36 ± 0.22), indicating that suppression of VDR expression eliminated the 1,25(OH)2D3-induced M1 macrophage switch to M2. The protein level showed the same change as the gene level. In addition, we further found that PPARγ was synchronously decreased after inhibition of VDR expression, which indicated that PPARγ may locate downstream of the vitamin D signaling pathway (Figure 9(b)). Immunofluorescence staining showed the change of each marker (Figure 10). In conclusion, the above results suggested that VDR-PPARγ cross talk may play an important role in the regulation of macrophage activation by 1,25-dihydroxyvitamin D3.


1,25-Dihydroxyvitamin D₃ Promotes High Glucose-Induced M1 Macrophage Switching to M2 via the VDR-PPARγ Signaling Pathway.

Zhang X, Zhou M, Guo Y, Song Z, Liu B - Biomed Res Int (2015)

The iNOS, MR, VDR, and PPARγ immunofluorescence expression after VDR siRNA intervention (200x).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4417570&req=5

fig10: The iNOS, MR, VDR, and PPARγ immunofluorescence expression after VDR siRNA intervention (200x).
Mentions: siRNA targeting VDR was transfected into RAW264.7 cells. A non-target control (NTC) siRNA was used to eliminate the nonspecific effects of the transfection reagents. All three specific VDR siRNAs inhibited VDR expression, but significant differences appeared only with VDR siRNA-1 (0.44 ± 0.05) and VDR siRNA-2 (0.47 ± 0.04) when compared with the control (1.15 ± 0.19) and NTC (1.00 ± 0.00) groups. The inhibition ratios of VDR siRNA-1, 2, and 3 were 56%, 53.5%, and 29.0%, respectively, so we used VDR siRNA-1 as the final intervention siRNA. NTC siRNA clearly showed no effect on VDR expression (Figure 8). As shown in Figure 9(a), depletion of VDR blocked the 1,25(OH)2D3-mediated increase in MR mRNA (VD versus VDR siRNA: 2.63 ± 0.61 versus 1.41 ± 0.44) and decrease in iNOS mRNA expression (VD versus VDR siRNA: 0.91 ± 0.07 versus 1.36 ± 0.22), indicating that suppression of VDR expression eliminated the 1,25(OH)2D3-induced M1 macrophage switch to M2. The protein level showed the same change as the gene level. In addition, we further found that PPARγ was synchronously decreased after inhibition of VDR expression, which indicated that PPARγ may locate downstream of the vitamin D signaling pathway (Figure 9(b)). Immunofluorescence staining showed the change of each marker (Figure 10). In conclusion, the above results suggested that VDR-PPARγ cross talk may play an important role in the regulation of macrophage activation by 1,25-dihydroxyvitamin D3.

Bottom Line: However, the above effects of 1,25-dihydroxyvitamin D3 were abolished when the expression of VDR and PPARγ was inhibited by VDR siRNA and a PPARγ antagonist.In addition, PPARγ was also decreased upon treatment with VDR siRNA.The above results demonstrate that active vitamin D promoted M1 phenotype switching to M2 via the VDR-PPARγ pathway.

View Article: PubMed Central - PubMed

Affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu 210009, China.

ABSTRACT
Macrophages, especially their activation state, are closely related to the progression of diabetic nephropathy. Classically activated macrophages (M1) are proinflammatory effectors, while alternatively activated macrophages (M2) exhibit anti-inflammatory properties. 1,25-Dihydroxyvitamin D3 has renoprotective roles that extend beyond the regulation of mineral metabolism, and PPARγ, a nuclear receptor, is essential for macrophage polarization. The present study investigates the effect of 1,25-dihydroxyvitamin D3 on macrophage activation state and its underlying mechanism in RAW264.7 cells. We find that, under high glucose conditions, RAW264.7 macrophages tend to switch to the M1 phenotype, expressing higher iNOS and proinflammatory cytokines, including TNFα and IL-12. While 1,25-dihydroxyvitamin D3 significantly inhibited M1 activation, it enhanced M2 macrophage activation; namely, it upregulated the expression of MR, Arg-1, and the anti-inflammatory cytokine IL-10 but downregulated the M1 markers. However, the above effects of 1,25-dihydroxyvitamin D3 were abolished when the expression of VDR and PPARγ was inhibited by VDR siRNA and a PPARγ antagonist. In addition, PPARγ was also decreased upon treatment with VDR siRNA. The above results demonstrate that active vitamin D promoted M1 phenotype switching to M2 via the VDR-PPARγ pathway.

No MeSH data available.


Related in: MedlinePlus