Effects of CpG-ODNs on phenotype and function of monocyte-derived dendritic cells in chronic hepatitis B

Abstract

Aim: To study the effects of synthetic nonmethylated CpG-containing oligodeoxynucleotides (CpG-ODNs), either alone or combined with recombinant Hepatitis B surface antigen (HBsAg) polypeptide, on the phenotype, function, and intracellular signaling pathways of monocyte-derived dendritic cells (DCs) in patients with chronic hepatitis B (CHB).

Methods: Peripheral blood monocytes isolated from CHB patients and healthy volunteers were induced to be dendritic cells by recombinant human granulocyte-monocyte colony stimulating factor and interleukin-4. The DCs were then treated with CpG-ODNs, CpG-ODNs/HBsAg, or tumor necrosis factor (TNF)-α for 18 h. The expression of surface molecules including HLA-DR, CD86, and CD1a in DCs were detected by flow cytometry, and the expression of signal transducers and activators of transcription (STAT1, 3, 4, 5, 6) and suppressors of cell signaling (SOCS1, 3) were determined by Western blotting assay. In addition, the capacity of DCs to stimulate allogeneic T lymphocytes and the amount of IL-12p70 released from DCs were measured.

Results: In the DCs derived from patients with CHB, treatment with TNF-α, CpG-ODNs, or CpG-ODNs/HBsAg, as compared to the vector control, significantly increased the expression of HLA-DR, stimulated the release of IL-12p70, and enhanced the capacity of DCs to stimulate allogenic T lymphocytes. The expressions of STAT1/4/6 and SOCS1/3, but not STAT3/5, were upregulated by TNF-α, CpG-ODNs, and CpG-ODNs/HBsAg. In addition, the expression of CD1a was upregulated only in the presence of both CpG-ODNs and HBsAg.

Conclusion: The treatment with CpG-ODNs, either alone or combined with HBsAg, has a remarkable stimulatory effect on the impaired phenotype and function of DCs in CHB, possibly by regulating the expression of STAT1, 4, 6 and SOCS1, 3.

Keywords: Chronic hepatitis B; CpG oligodeoxynucleotides; Dendritic cell; Hepatitis B surface antigen; Signal transduction.

Figure 1

A representative image of monocyte-derive dendritic cells under transmission electron microscope after 7-d induction with recombinant granulocyte-macrophage colony-stimulating factor and interleukin-4 (magnification × 7500). Dendritic cells were irregular in form, and abundant in extended beard-like prick and mitochondria in cytoplasm.

Figure 2

Expression levels of cytoplasmic signal transducers and activators of transcription and suppressors of cell signaling in dendritic cells stimulated with different immunologic adjuvants. 1: Dendritic cells (DCs) from healthy subjects stimulated with synthetic nonmethylated CpG-containing oligodeoxynucleotides (CpG-ODNs); 2-5: DCs from patients with chronic hepatitis B (CHB) stimulated respectively with PBS, CpG-ODNs, TNF-α and CpG-ODNs plus HBsAg. CpG, CpG + HBsAg, TNF-α, and HBsAg are the different adjuvants on DCs. STAT1, 3, 4, 5 and SOCS1, 3 respectively represents the expressing levels of the intracellular signaling molecules including signal transducers and activators of transcription-1, 3, 4, 5 and suppressors of cell signaling-1, 3 in CHB-derived DCs. HBsAg: Hepatitis B surface antigen; TNF: Tumor necrosis factor.