Mitigation of monocyte inflammation by inhibition of sodium phosphate co-transporter with phosphonoformic acid and parthenolide in diabetic nephropathy uremia
Purpose: To investigate the effect of sodium phosphate co-transporter (Pit-1) on the regulation of monocyte inflammation in diabetic nephropathy uremia (DNU) patients and the underlying principles of inflammatory immune response during DNU pathogenesis.
Methods: The levels of CD14+ CD16+ and Pit-1 on peripheral blood mononuclear cells (PBMC) were measured by flow cytometry. Serum C-reactive protein (CRP) and 25(OH)D3 were detected by immunoturbidimetry while IL-6 and MCP-1 were assayed with enzyme-linked immunoassay (ELISA). The amounts of vitamin D receptors (VDRs) and Pit-1 mRNA in human acute monocytic leukemia cell lines (THP-1) were determined by quantitative real-time polymerase chain reaction (qRT-PCR), while western blot was utilized for measurement of NF-κB p65 and p-STAT5.
Results: Compared to the healthy group, DNU patients showed markedly higher CD14+CD16+, Pit-1, CRP, IL-6 and MCP-1, while 25(OH) D3 was reduced. Following stimulation with PFA or PTN, comparison with DNU group revealed that THP-1 monocytes showed a significant down-regulation of Pit-1 (1.34 ± 0.06 for PFA; 1.60 ± 0.25 for PTN; p < 0.05); NF-κB p65 (2.65 ± 0.25 for PFA; 3.88 ± 0.13 for PTN; p < 0.01), p-STAT5 (2.49 ± 0.10 for PFA; 3.03 ± 0.09 for PTN; p < 0.01) and a significant decrease in levels of IL-6 (55.38 ± 3.22 for PFA, 68.68 ± 6.01 for PTN; p < 0.05); MCP-1( 39.67 ± 3.62 for PFA; 52.62 ± 5.00 for PTN; p < 0.01), except for VDR (0.64 ± 0.15 for PFA, 0.43 ± 0.03 for PTN; p < 0.05) .
Conclusion: The level of expression of Pit-1 has a positive correlation with the level of inflammatory monocytes, which indicates that Pit-1 can be used as a new biomarker for DNU diagnosis. In addition, since Pit-1 is connected to NF-κB and STAT5 signaling pathways which are critical to inflammatory immune response, development of drugs that target Pit-1 could be an approach in developing new strategies for DNU therapy.
Keywords: Pit-1, Diabetic nephropathy, Uremia, Monocytes, Inflammation, NF-κB, STAT5
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