CXC chemokine receptor 4 expression and stromal cell-derived factor-1α-induced chemotaxis in CD4+ T lymphocytes are regulated by interleukin-4 and interleukin-10

摘要

We report that interleukin (IL)-4 and IL-10 can significantly up- or down-regulate CXC chemokine receptor 4 (CXCR4) expression on CD4⁺ T lymphocytes, respectively. Stromal cell-derived factor-1α (SDF-1α)-induced CD4⁺ T-lymphocyte chemotaxis was also correspondingly regulated by IL-4 and IL-10. IL-4 and IL-10 up- or down-regulated CXCR4 mRNA expression in CD4⁺ T lymphocytes, respectively, as detected by real-time quantitative reverse transcription–polymerase chain reaction (RT–PCR). Scatchard analysis revealed a type of CXCR4 with affinity (Kd ≈ 6·3 nm), and ≈ 70 000 SDF-1α-binding sites per cell, among freshly isolated CD4⁺ T lymphocytes, and two types of CXCR4 with different affinities (Kd1 ≈ 4·4 nm and Kd2 ≈ 14·6 nm), and a total of ≈ 130 000 SDF-1α-binding sites per cell, among IL-4-stimulated CD4⁺ T lymphocytes. The regulation of CXCR4 expression in CD4⁺ T lymphocytes by IL-4 and IL-10 could be blocked by a selective inhibitor of protein kinase (staurosporine) or by a selective inhibitor of cAMP- and cGMP-dependent protein kinase (H-8), indicating that these cytokines regulate CXCR4 on CD4⁺ T lymphocytes via both cAMP and cGMP signalling pathways. The fact that cyclosporin A or ionomycin were able to independently change the CXCR4 expression and block the effects of IL-4 and IL-10 on CXCR4 expression implied that the capacity of IL-4 and IL-10 to regulate CXCR4 on CD4⁺ T lymphocytes is not linked to calcium-mobilization stimulation. These results indicate that the effects of IL-4 and IL-10 on the CXCR4–SDF-1 receptor–ligand pair may be of particular importance in the cytokine/chemokine environment concerning the inflammatory processes and in the progression of human immunodeficiency virus (HIV) infection.