TGF-β1 prevents up-regulation of the P2X7 receptor by IFN-γ and LPS in leukemic THP-1 monocytes

• Published in: Biochimica et biophysica acta 2010-11, Vol.1798 (11), p.2058-2066
• Main Authors: Gadeock, Safina, Tran, Jimmy N.S.N., Georgiou, Jennifer G., Jalilian, Iman, Taylor, Rosanne M., Wiley, James S., Sluyter, Ronald
• Format: Article
• Language: English
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - analogs & derivatives; 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - pharmacology; Adenosine Triphosphate - pharmacology; Antigens, CD - analysis; Apyrase - analysis; B7-2 Antigen - analysis; Cells, Cultured; Humans; Inflammation; Interferon-gamma - pharmacology; Lipopolysaccharide Receptors - analysis; Lipopolysaccharides - pharmacology; Macrophage; Monocyte; Monocytes - chemistry; Monocytes - drug effects; P2X receptor; Purinergic receptor; Receptors, Purinergic P2 - analysis; Receptors, Purinergic P2 - drug effects; Receptors, Purinergic P2 - genetics; Receptors, Purinergic P2 - physiology; Receptors, Purinergic P2X7; Transforming growth factor; Transforming Growth Factor beta1 - pharmacology; Up-Regulation
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2010.07.022

The P2X7 receptor is an extracellular ATP-gated cation channel critical in inflammation and immunity, and can be up-regulated by IFN-γ and LPS. This study aimed to examine the effect of TGF-β1 on the up-regulation of P2X7 function and expression in leukemic THP-1 monocytes differentiated with IFN-γ and LPS. Cell-surface molecules including P2X7 were examined by immunofluorescence staining. Total P2X7 protein and mRNA was assessed by immunoblotting and RT-PCR respectively. P2X7 function was evaluated by ATP-induced cation dye uptake measurements. Cell-surface P2X7 was present on THP-1 cells differentiated for 3 days with IFN-γ and LPS but not on undifferentiated THP-1 cells. ATP induced ethidium + uptake into differentiated but not undifferentiated THP-1 cells, and the P2X7 antagonist, KN-62, impaired ATP-induced ethidium + uptake. Co-incubation of cells with TGF-β1 plus IFN-γ and LPS prevented the up-regulation of P2X7 expression and ATP-induced ethidium + uptake in a concentration-dependent fashion with a maximum effect at 5 ng/ml and with an IC 50 of ~ 0.4 ng/ml. Moreover, ATP-induced YO-PRO-1 2+ uptake and IL-1β release were abrogated in cells co-incubated with TGF-β1. TGF-β1 also abrogated the amount of total P2X7 protein and mRNA induced by IFN-γ and LPS. Finally, TGF-β1 prevented the up-regulation of cell-surface CD86, but not CD14 and MHC class II, by IFN-γ and LPS. These results indicate that TGF-β1 prevents the up-regulation of P2X7 function and expression by IFN-γ and LPS in THP-1 monocytes. This suggests that TGF-β1 may limit P2X7-mediated processes in inflammation and immunity.