I-mfa stimulates MCP-1 production by glomerular mesangial cells

Background: Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease. Renal inflammation is known to contribute to the onset and progression of the disease. Glomerular mesangial cells (MCs) are the major cell type involved in the pathogenesis of DKD. Monocyte chemoattracting protein 1 (MCP-1) is one of major inflammatory cytokines produced by MCs in DKD. Inhibitor of MyoD family A (I-mfa) is a small cytosolic protein that functions as a transcription modulator regulating transcription activity of multiple genes. Recently, we found that I-mfa was expressed in glomerular MCs. However, its function in MCs, particularly its association with MC pathology is not known. The aim of the present study was to determine if I-mfa stimulated production of MCP-1 and extracellular matrix proteins by MCs. Methods: Human MCs were cultured in high glucose (HG, 25 mM) or normal glucose (NG, 5 mM) with/without transfection with human I-mfa expression plasmid or empty vector as the control using lipofectomine 3000. The protein abundance of I-mfa and MCP-1 was assessed by western blot of the whole cell lysates. qRT-PCR was used to evaluate the mRNA level of MCP-1. Diabetes was generated in male I-mfa+/+ and I-mfa-/- mice by multiple low-dose streptozotocin (STZ) (50 mg/kg, Sigma-Aldrich) injection (intraperitoneal, once one day for 5 days). Mice of non diabetes (non Db) were injected with 10 mM citrate buffer (vehicle). Immunofluorescence staining and immunohistochemistry in paraffin embedded kidney sections were used to evaluate glomerular I-mfa level and glomerular macrophage infiltration, respectively. Results: High glucose treatment increased I-mfa protein abundance in MCs. I-mfa expression in glomerulus/MCs was upregulated in mice with DKD. Abundance of MCP-1 was significantly greater at both mRNA and protein levels in I-mfa-transfected MCs compared to cells both without transfection and control transfection. Furthermore, diabetes significantly increased deposition of macrophages in glomerulus of I-mfa+/+ mice. However, this inflammatory response was significantly mitigated in I-mfa-/- mice. Conclusion: I-mfa stimulates production of MCP-1 by MCs and macrophage infiltration in diabetic kidney. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.