Toll-Like Receptor 4 Signaling is Involved in IgA-Stimulated Mesangial Cell Activation
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Purpose: Deposition of polymeric IgA1 in the kidney mesangium is the hallmark of IgA nephropathy, but the molecular mechanisms of IgA-mediated mesangial responses and inflammatory injuries remain poorly understood. We hypothesize that Toll-like receptor 4 (TLR4) is involved in IgA-induced mesangial cell activation. Materials and Methods: Mouse mesangial cells were stimulated with lipopolysaccharide (LPS) (1 μg/mL), IgA (20 μg/mL), or both, and TLR4 expression was measured by real time RT-PCR and Western blot. Intracellular responses to LPS or IgA were assessed by Western blot for ERK1/2, JNK, p38 MAP kinases (MAPKs), Iκ-Bα degradation and fibronectin secretion. MCP-1 secretion was assessed by ELISA. Small interfering RNA (siRNA) of TLR4 was used to confirm that the effects were caused by TLR4 activity. Results: LPS- or IgA-treatment upregulated the levels of TLR4 mRNA and protein in cultured MMC at 24 h. LPS and IgA induced rapid phosphorylation of MAPKs, but degradation of Iκ-Bα was observed only in LPS-treated MMC. LPS, but not IgA, induced increased secretion of MCP-1 and fibronectin at 24 h or 48 h. Combined LPS and IgA treatment did not cause additional increases in TLR4 mRNA and protein levels or Iκ-Bα degradation,and MCP-1 and fibronectin secretions were less than with LPS alone. LPS- or IgA-induced TLR4 protein levels and MAPK activation were inhibited by transfection with TLR4 siRNA. Conclusion: These results indicate that the activation of MAPKs and MCP-1 secretion are mediated by TLR4, at least in part, in IgA-treated mesangial cells. TLR4 is involved in mesangial cell injury by induction of pro-inflammatory cytokines in IgA nephropathy.
Abstract
Purpose: Deposition of polymeric IgA1 in the kidney mesangium is the hallmark of IgA nephropathy, but the molecular mechanisms of IgA-mediated mesangial responses and inflammatory injuries remain poorly understood. We hypothesize that Toll-like receptor 4 (TLR4) is involved in IgA-induced mesangial cell activation. Materials and Methods: Mouse mesangial cells were stimulated with lipopolysaccharide (LPS) (1 μg/mL), IgA (20 μg/mL), or both, and TLR4 expression was measured by real time RT-PCR and Western blot. Intracellular responses to LPS or IgA were assessed by Western blot for ERK1/2, JNK, p38 MAP kinases (MAPKs), Iκ-Bα degradation and fibronectin secretion. MCP-1 secretion was assessed by ELISA. Small interfering RNA (siRNA) of TLR4 was used to confirm that the effects were caused by TLR4 activity. Results: LPS- or IgA-treatment upregulated the levels of TLR4 mRNA and protein in cultured MMC at 24 h. LPS and IgA induced rapid phosphorylation of MAPKs, but degradation of Iκ-Bα was observed only in LPS-treated MMC. LPS, but not IgA, induced increased secretion of MCP-1 and fibronectin at 24 h or 48 h. Combined LPS and IgA treatment did not cause additional increases in TLR4 mRNA and protein levels or Iκ-Bα degradation,and MCP-1 and fibronectin secretions were less than with LPS alone. LPS- or IgA-induced TLR4 protein levels and MAPK activation were inhibited by transfection with TLR4 siRNA. Conclusion: These results indicate that the activation of MAPKs and MCP-1 secretion are mediated by TLR4, at least in part, in IgA-treated mesangial cells. TLR4 is involved in mesangial cell injury by induction of pro-inflammatory cytokines in IgA nephropathy.
참고문헌 (21)
- Akira S, "Pathogen recognition and innate immunity", Cell, 124, pp.783~801 (2006)
- Kawai T, "Pathogen recognition with Toll-like receptors", Curr Opin Immunol, 17, pp.338~344 (2005)
- Anders HJ, "Toll-like receptors: emerging concepts in kidney disease", Curr Opin Nephrol Hypertens, 16, pp.177~183 (2007)
- El-Achkar TM, "Renal Toll-like receptors: recent advances and implications for disease", Nat Clin Pract Nephrol, 2, pp.568~581 (2006)
- Kuki K, "Immunity of tonsil and IgA nephropathy--relationship between IgA nephropathy and tonsillitis", Acta Otolaryngol Suppl, 124, pp.6~9 (2004)
- Coppo R, "Toll-like receptor 4 expression is increased in circulating mononuclear cells of patients with immunoglobulin A nephropathy", Clin Exp Immunol, 159, pp.73~81 (2010)
- Patole PS, "Expression and regulation of Toll-like receptors in lupus-like immune complex glomerulonephritis of MRL-Fas(lpr) mice", Nephrol Dial Transplant, 21, pp.3062~3073 (2006)
- Brown HJ, "Toll-like receptor 4 ligation on intrinsic renal cells contributes to the induction of antibody-mediated glomerulonephritis via CXCL1 and CXCL2", J Am Soc Nephrol, 18, pp.1732~1739 (2007)
- Mattii L, "Kidney expression of RhoA, TGF-beta1, and fibronectin in human IgA nephropathy", Nephron Exp Nephrol, 101, pp.e16~e23 (2005)
- Kwon J, "Toll-like Receptor Expression in Patients With Renal Allograft Dysfunction", Transplantation Proceedings, 40(10), pp.3479~3480 (2008)
- Suzuki H, "Toll-like receptor 9 affects severity of IgA nephropathy", J Am Soc Nephrol, 19, pp.2384~2395 (2008)
- Allen AC, "Galactosylation of N- and O-linked carbohydrate moieties of IgA1 and IgG in IgA nephropathy", Clin Exp Immunol, 100, pp.470~474 (1995)
- Wolf G, "Angiotensin II upregulates toll-like receptor 4 on mesangial cells", J Am Soc Nephrol, 17, pp.1585~1593 (2006)
- Chen HC, "Induction of heat shock protein 70 protects mesangial cells against oxidative injury", Kidney Int, 56, pp.1270~1273 (1999)
- Lim BJ, "Renal tubular expression of Toll-like receptor 4 in cyclosporine nephrotoxicity", Apmis, 117(8), pp.583~591 (2009)
- Duque N, "Interaction of IgA with Fc alpha receptors of human mesangial cells activates transcription factor nuclear factor-kappa B and induces expression and synthesis of monocyte chemoattractant protein-1, IL-8, and IFN-inducible protein 10", J Immunol, 159, pp.3474~3482 (1997)
- Ka SM, "Mesangial cells of lupus-prone mice are sensitive to chemokine production", Arthritis Res Ther, 9, pp.R67~ (2007)
- Wolf HM, "Anti-inflammatory properties of human serum IgA: induction of IL-1 receptor antagonist and Fc alpha R (CD89)-mediated down-regulation of tumour necrosis factor-alpha (TNF-alpha) and IL-6 in human monocytes", Clin Exp Immunol, 105, pp.537~543 (1996)
- Olas K, "Immunomodulatory properties of human serum immunoglobulin A: anti-inflammatory and pro-inflammatory activities in human monocytes and peripheral blood mononuclear cells", Clin Exp Immunol, 140, pp.478~490 (2005)
- Shimosawa M, "Lipopolysaccharide-triggered acute aggravation of mesangioproliferative glomerulonephritis through activation of coagulation in a high IgA strain of ddY mice", Nephron Exp Nephrol, 112, pp.e81~e91 (2009)
- Arima S, "Significance of mononuclear phagocytes in IgA nephropathy", Kidney Int, 39, pp.684~692 (1991)