[Pioglitazone inhibits dendritic cell adhesion and transmigration through down-regulation of dendritic cell-specific intercellular adhesion molecule-3 grabbing nonintegrin].

OBJECTIVE

To investigate the effect of pioglitazone (Pio) on dendritic cell-(DC) specific intercellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) expression in DCs and explore the possible mechanism of Pio inhibiting DC adhesion and transmigration.

METHODS

DCs derived from human peripheral blood mononuclear cells were cultured and divided into 6 groups: blank control group, Pio 0.1 micromol/L group, Pio 1.0 micromol/L group, Pio 10 micromol/L group, GW9662, a peroxisome proliferator activated receptor (PPAR)-gamma antagonist, 10 micromol/L group, and GW9662 10 micromol/L + Pio 10 micromol/L group. Western blotting was used to detect the protein expression of DC-SIGN 24 h later. Human umbilical vein endothelial cells (HUVECs) were obtained and co-cultured with the DCs undergoing different treatments. Immunofluorescence test was used to detect the protein expression of DC-SIGN. DCs labeled with 5-chloromethylfluorescein diacetate (CMFDA) were added into the monocellular layer of fused ECs. Blank DCs and DCs pretreated with anti-DC-SIGN antibody were used as blank and experimental groups. Laser confocal microscopy was used to observe the adhesion ability of the DCs. HUVECs were inoculated into the upper chamber of Transwell plate and CMFDA-labeled DCs of above mentioned groups were added to the mono-cellular layer of these ECs. Serum-free culture medium with monocyte chemoattractant protein-1 was added into the lower chamber. Eight hours later the transmigration ability was observed.

RESULTS

Western blotting showed that the DC-SIGN protein expression levels of the DCs of the Pio 1.0 micromol/L and Pio 10 micromol/L group were 0.96 +/- 0.09 and 0.80 +/- 0.08 respectively, both significantly lower than that of the blank control group (1.25 +/- 0.23, P < 0.05 and P < 0.01); and the DC-SIGN protein expression level of the GW9662 10 micromol/L + Pio 10 micromol/L group was 1.10 +/- 0.12, significantly higher than that of the Pio 10 micromol/L group (P < 0.05). Immunofluorescence test showed that the DC-SIGN protein expression levels of the DCs of the Pio 1.0 micromol/L and Pio 10 micromol/L group were 22.3 +/- 5.4 and 14.4 +/- 2.3 respectively, both significantly lower than that of the control group (29.5 +/- 5.1, P < 0.05 and P < 0.01), and the DC-SIGN protein expression level of the GW9662 10 micromol/L + Pio 10 micromol/L group was 24.9 +/- 4.3, significantly higher than that of the Pio 10 micromol/L group (P < 0.01), and not significantly different from that of the blank control group (P > 0.05). The adhesion rates of the Pio 1.0 micromol/L and Pio 10 micromol/L groups were 10.8% +/- 2.0% and 7.6% +/- 1.5% respectively, both significantly lower than that of the control group (13.4% +/- 2.1%, P < 0.05 and P < 0.01); and the adhesion rate of the GW9662 + Pio 10 micromol/L group was 12.1% +/- 1.9%, significantly higher than that of the Pio 10 micromol/L group (P < 0.01), and not significantly different from that of the blank control group (P > 0.05). The transmigration inhibition rate of DCs of the Pio 0.1, 1.0, and 10 micromol/L groups were 4.1%, 12.9%, and 17.2% compared with the transmigration rate of the blank control group (P < 0.05, P < 0.05, and P < 0.01). The transmigration rate of the GW9662 + Pio 10 micromol/L group was significantly higher than that of the Pio 10 micromol/L group (P < 0.05), and not significantly different from that of the blank control group (P > 0.05). The transmigration rate of the anti-DC-SIGN intervention group was lower by 17.8% than that of the control group (P < 0.01).

CONCLUSION

Pio down-regulates the DC-SIGN protein expression and inhibits DC adhesion and transmigration through the pathway of PPAR-gamma.