Impact Of Hydroxychloroquine On Plasmacytoid Dendritic Cells Activated By CpG-ODN

Objective To investigate the impact of hydroxychloroquine onplasmacytoid dendritic cells activation induced by CpG-ODN and signalingpathway of TLR-like receptor9and myeloid differentiation factor88invitro，to further understand the mechanism of action of hydroxychloroquinein the treatment of systemic lupus erythematosus.Methods PBMC from10patients with systemic lupus erythematosuswere collected. Expressions of TLR9and MyD88mRNA in PBMC weredetected using RT-PCR after co-cultured with CpG-ODN2216orCpG-ODN2216plus HCQ. Thirty-six cord blood were collected fromdelivery room. Monocytes were obtained from250-300ml cord blood usingdensity gradient centrifugation. BDCA-4beads sorting was used to obtainthe precursor pDCs. Precursor pDCs were co-cultured with IL-3, IL-3plusCpG-ODN2216or IL-3plus CpG-ODN2216and HCQ for3days. Flowcytometry was used to measure surface expression of BDCA-2, CD86andCD32on the pDCs. The concentration of IFN-α in the supernatants wasdetected using ELISA. Result①TLR-9and MyD88mRNA expression of PBMC from SLEpatients were significantly lower in CpG-ODN plus HCQ group than that inCpG-ODN group (P <0.05).②BDCA-2expression and MFI on pDCswere significantly lower in IL-3plus CpG-ODN group than that in IL-3group(P<0.05).③CD86and CD32expression and MFI on pDCs weresignificantly higher in IL-3plus CpG-ODN group than that in IL-3group(P<0.05).④IFN-α concentration in the supernatant was significantlyhigher in IL-3plus CpG-ODN group than that in IL-3group(P <0.05).⑤CD32expression and MFI were significantly lower in IL-3plusCpG-ODNandHCQ group than that in IL-3plus CpG-ODN group(P<0.05)；IFN-αconcentration in the supernatant was significantly lower inIL-3+CpG-ODN+HCQ group than that in IL-3+CpG-ODN group (P<0.05).⑥Compared with IL-3+CpG-ODN group, BDCA-2and CD86expression and MFI on pDCs in IL-3plus CpG-ODN and HCQ group hada tendency to increase, but the difference was not statistically significant(P>0.05).Conclusion HCQ may inhibit the activation of the pDCs and thesecretion of IFN-α induced by CpG-ODN2216via reduction of CD32expression on pDCs and inhibition of downstream signal transduction ofTLR9and MyD88.