Effects of 1,25-(OH)2D3 on the expressions of vitamin D receptor, STAT5 and cytoskeletal rearrangement in human monocytes incubated with sera from type 2 diabetes patients and diabetic nephropathy patients with uremia
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To explore the effects of 1,25-(OH)2D3 and lipopolysaccharide (LPS) plus human recombinant interleukin-15 (IL-15) on expression of vitamin D receptor (VDR) and STAT5, and cytoskeletal rearrangement in human monocytes incubated with sera from type 2 diabetes (T2DM) patients and diabetic nephropathy (DN) patients with uremia.
Materials and methods
Peripheral sera were isolated from healthy volunteers (control group, T2DM patients and DN uremic non-dialysis patients). After incubation with or without 1,25(OH)2D3, THP-1 monocytes were treated with LPS plus IL-15 prior to the collection of cells and supernatants. VDR mRNA transcription was examined by RT-PCR, whilst THP-1 monocytic VDR, STAT5 and p-STAT5 expressions were investigated by Western blotting. Concentrations of IL-6 and monocyte chemoattractant protein-1 (MCP-1) in supernatants were assessed by ELISA. Immunofluorescence and a laser confocal microscopy was used to examine the expression of VDR and cytoskeletal proteins.
Compared to the normal control, LPS and IL-15 down-regulate monocytic VDR expression in T2DM patients and DN uremic patients, whilst with cytoskeletal rearrangement, they up-regulate p-STAT5 expression as well as IL-6 and MCP-1 activity. Such effects could be in part blocked by 1,25-(OH)2D3.
The above results suggest that the anti-inflammatory mechanism of 1,25-(OH)2D3 may be related to cytoskeletal proteins, VDR and STAT5 signaling pathway.
Keywords1,25-(OH)2D3 Type 2 diabetes mellitus Diabetic nephropathy Uremia Monocytes
We thank Professor Qifu Li, Dr Lai Han and Wei Xue Tang, for their cooperation in patient collection and design of the study and data analysis. This study was supported in part by the outstanding doctoral dissertation fund of Chongqing Medical University. Supported by the Key Project of Chongqing Municipal Health Bureau (2010-1-16).
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