Midkine inhibits inducible regulatory T cell differentiation by suppressing the development of tolerogenic dendritic cells.

Abstract

Midkine (MK), a heparin-binding growth factor, reportedly contributes to inflammatory diseases, including Crohn's disease and rheumatoid arthritis. We previously showed that MK aggravates experimental autoimmune encephalomyelitis (EAE) by decreasing regulatory CD4(+)CD25(+)Foxp3(+) T cells (Tregs), a population that regulates the development of autoimmune responses, although the precise mechanism remains uncertain. In this article, we show that MK produced in inflammatory conditions suppresses the development of tolerogenic dendritic cells (DCregs), which drive the development of inducible Treg. MK suppressed DCreg-mediated expansion of the CD4(+)CD25(+)Foxp3(+) Treg population. DCregs expressed significantly higher levels of CD45RB and produced significantly less IL-12 compared with conventional dendritic cells. However, MK downregulated CD45RB expression and induced IL-12 production by reducing phosphorylated STAT3 levels via src homology region 2 domain-containing phosphatase-2 in DCreg. Inhibiting MK activity with anti-MK RNA aptamers, which bind to the targeted protein to suppress the function of the protein, increased the numbers of CD11c(low)CD45RB(+) dendritic cells and Tregs in the draining lymph nodes and suppressed the severity of EAE, an animal model of multiple sclerosis. Our results also demonstrated that MK was produced by inflammatory cells, in particular, CD4(+) T cells under inflammatory conditions. Taken together, these results suggest that MK aggravates EAE by suppressing DCreg development, thereby impairing the Treg population. Thus, MK is a promising therapeutic target for various autoimmune diseases.

• Authors: Yoshifumi Sonobe, Hua Li, Shijie Jin, Satoshi Kishida, Kenji Kadomatsu, Hideyuki Takeuchi, Tetsuya Mizuno, Akio Suzumura
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 188 Issue 6 Pg. 2602-11 (Mar 15 2012) ISSN: 1550-6606 [Electronic] United States
• PMID: 22323540 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adoptive Transfer
• Animals
• Blotting, Western
• Cell Differentiation (immunology)
• Cell Separation
• Dendritic Cells (immunology, metabolism)
• Encephalomyelitis, Autoimmune, Experimental (immunology, metabolism, pathology)
• Enzyme-Linked Immunosorbent Assay
• Female
• Flow Cytometry
• Immune Tolerance (immunology)
• Lymphocyte Activation (immunology)
• Lymphocyte Culture Test, Mixed
• Mice
• Mice, Inbred BALB C
• Mice, Inbred C57BL
• Real-Time Polymerase Chain Reaction
• Reverse Transcriptase Polymerase Chain Reaction
• T-Lymphocytes, Regulatory (cytology, immunology, metabolism)