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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 effect of high glucose on the activity of iNOS. (a) RAW264.7 cells were stimulated with glucose in a dose- (11.1 mM, 20 mM, 25 mM, and 30 mM) dependent manner. After 24 h, the cells were collected. A concentration of 11.1 mM glucose was used as the control. *P < 0.05 versus control; (b) RAW264.7 cells were stimulated with glucose in a time- (0 h, 6 h, 12 h, 24 h, 36 h, and 48 h) dependent manner. A concentration of 11.1 mM glucose was used as the control. Data are presented as the mean ± SD (n = 3-4 per group). #P < 0.05 versus control at the same time point; &P < 0.05 versus 0 h in the same group.
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fig1: The effect of high glucose on the activity of iNOS. (a) RAW264.7 cells were stimulated with glucose in a dose- (11.1 mM, 20 mM, 25 mM, and 30 mM) dependent manner. After 24 h, the cells were collected. A concentration of 11.1 mM glucose was used as the control. *P < 0.05 versus control; (b) RAW264.7 cells were stimulated with glucose in a time- (0 h, 6 h, 12 h, 24 h, 36 h, and 48 h) dependent manner. A concentration of 11.1 mM glucose was used as the control. Data are presented as the mean ± SD (n = 3-4 per group). #P < 0.05 versus control at the same time point; &P < 0.05 versus 0 h in the same group.

Mentions: In order to ascertain the optimum glucose concentration and time point, RAW264.7 cells were first stimulated with glucose in dose- (11.1 mM, 20 mM, 25 mM, and 30 mM) and time- (0 h, 6 h, 12 h, 24 h, 36 h, and 48 h) dependent manners, and the activity of inducible nitric oxide synthase (iNOS) was measured. As shown in Figure 1(a), the iNOS activity was increased by glucose in a dose-dependent manner. Particularly, 25 mM glucose gave the maximum response, and there was no difference between the control group and mannitol group, which excluded the effect of hyperosmolarity. As shown in Figure 1(b), from 0 h to 24 h, the iNOS activity increased in a time-dependent manner, and the peak level was achieved at 24 h after 25 mM glucose intervention. Then, there was a sharp decline in iNOS activity after 24 h. From 36 to 48 h, no significant difference in iNOS activity was found between high glucose and the control group. Thus, we used the 25 mM glucose concentration and 24 h time period in later experiments. Then, we explored the effect of glucose on macrophage phenotype by quantifying TNF-α and IL-12 in the supernatant and the expression of cell-specific markers of M1 and M2. As we can see, 25 mM glucose induced more secretion of inflammatory cytokines, including TNF-α and IL-12, in the supernatant, while anti-inflammatory IL-10 was not influenced (Figure 2 and Table 1). Similarly, when compared with the control, high glucose also stimulated high expression of an M1 marker, iNOS, but downregulated the expression of the M2 markers MR and Arg-1, which accorded with the classical activation model of M1 macrophages (Figure 3 and Table 2).


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 effect of high glucose on the activity of iNOS. (a) RAW264.7 cells were stimulated with glucose in a dose- (11.1 mM, 20 mM, 25 mM, and 30 mM) dependent manner. After 24 h, the cells were collected. A concentration of 11.1 mM glucose was used as the control. *P < 0.05 versus control; (b) RAW264.7 cells were stimulated with glucose in a time- (0 h, 6 h, 12 h, 24 h, 36 h, and 48 h) dependent manner. A concentration of 11.1 mM glucose was used as the control. Data are presented as the mean ± SD (n = 3-4 per group). #P < 0.05 versus control at the same time point; &P < 0.05 versus 0 h in the same group.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4417570&req=5

fig1: The effect of high glucose on the activity of iNOS. (a) RAW264.7 cells were stimulated with glucose in a dose- (11.1 mM, 20 mM, 25 mM, and 30 mM) dependent manner. After 24 h, the cells were collected. A concentration of 11.1 mM glucose was used as the control. *P < 0.05 versus control; (b) RAW264.7 cells were stimulated with glucose in a time- (0 h, 6 h, 12 h, 24 h, 36 h, and 48 h) dependent manner. A concentration of 11.1 mM glucose was used as the control. Data are presented as the mean ± SD (n = 3-4 per group). #P < 0.05 versus control at the same time point; &P < 0.05 versus 0 h in the same group.
Mentions: In order to ascertain the optimum glucose concentration and time point, RAW264.7 cells were first stimulated with glucose in dose- (11.1 mM, 20 mM, 25 mM, and 30 mM) and time- (0 h, 6 h, 12 h, 24 h, 36 h, and 48 h) dependent manners, and the activity of inducible nitric oxide synthase (iNOS) was measured. As shown in Figure 1(a), the iNOS activity was increased by glucose in a dose-dependent manner. Particularly, 25 mM glucose gave the maximum response, and there was no difference between the control group and mannitol group, which excluded the effect of hyperosmolarity. As shown in Figure 1(b), from 0 h to 24 h, the iNOS activity increased in a time-dependent manner, and the peak level was achieved at 24 h after 25 mM glucose intervention. Then, there was a sharp decline in iNOS activity after 24 h. From 36 to 48 h, no significant difference in iNOS activity was found between high glucose and the control group. Thus, we used the 25 mM glucose concentration and 24 h time period in later experiments. Then, we explored the effect of glucose on macrophage phenotype by quantifying TNF-α and IL-12 in the supernatant and the expression of cell-specific markers of M1 and M2. As we can see, 25 mM glucose induced more secretion of inflammatory cytokines, including TNF-α and IL-12, in the supernatant, while anti-inflammatory IL-10 was not influenced (Figure 2 and Table 1). Similarly, when compared with the control, high glucose also stimulated high expression of an M1 marker, iNOS, but downregulated the expression of the M2 markers MR and Arg-1, which accorded with the classical activation model of M1 macrophages (Figure 3 and Table 2).

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