The lectin-like domain of thrombomodulin interferes with complement activation and protects against diabetic nephropathy

Abstract. The presence of plasma proteins in the tubular lumen has variety of adverse effects on the tubular cells. Among various plasma proteins filtered through glomerular barrier, complement has been proven as the possible candidate inducing tubulointerstitial injury. To study the role of intratubular complement activation in proteinuric patients, complement activation products (CAP) at C3 level (iC3b and Bb) and C9 level (membrane attack complex) were measured in both plasma and urine of patients with minimal change nephrotic syndrome (MCNS), focal glomerular sclerosis, IgA nephropathy, membranous nephropathy, and diabetic nephropathy. For evaluation of the effect of metabolic acidosis on the intratubular complement activation, urinary CAP were measured before and after sodium bicarbonate administration in patients with renal insufficiency. The following results were obtained: (1) Patients with focal glomerular sclerosis and diabetic nephropathy showed the highest level of urinary CAP excretion rate (unit/creatinine), while MCNS revealed no increase. (2) Patients with membranous nephropathy showed a unique finding,i.e., isolated increase of membrane attack complex excretion. (3) There was no significant correlation between urine and plasma levels of CAP. (4) Except for MCNS patients, the urinary excretion rate of CAP significantly increased when the level of proteinuria exceeded the nephrotic range, and it was significantly correlated with the serum creatinine level. (5) Urinary CAP excretion rate significantly decreased 2 wk after sodium bicarbonate administration without affecting the level of proteinuria or plasma CAP. These results suggest that the degree of intratubular complement activation correlates with the level of proteinuria, type of glomerular disease, impairment of renal function, and metabolic acidosis.

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Extra-immunological role of complement activation in diabetic nephropathy

OA Nephrology ◽

10.13172/2053-0293-1-2-900 ◽

2013 ◽

Vol 1 (2) ◽

Cited By ~ 1

Author(s):

T Fujita

Keyword(s):

Diabetic Nephropathy ◽

Complement Activation

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The lectin-like domain of thrombomodulin ameliorates diabetic glomerulopathy via complement inhibition

Thrombosis and Haemostasis ◽

10.1160/th12-07-0460 ◽

2012 ◽

Vol 108 (12) ◽

pp. 1141-1153 ◽

Cited By ~ 29

Author(s):

Ilya Vinnikov ◽

Khurrum Shahzad ◽

Fabian Bock ◽

Satish Ranjan ◽

Juliane Wolter ◽

...

Keyword(s):

Endothelial Cells ◽

Diabetic Nephropathy ◽

Complement Activation ◽

Protein C ◽

Interactive Systems ◽

Diabetic Glomerulopathy ◽

Podocyte Injury ◽

Complement Inhibition ◽

Discrete Domains ◽

Complement Deposition

SummaryCoagulation and complement regulators belong to two interactive systems constituting emerging mechanisms of diabetic nephropathy. Thrombomodulin (TM) regulates both coagulation and complement activation, in part through discrete domains. TM’s lectin like domain dampens complement activation, while its EGF-like domains independently enhance activation of the anticoagulant and cytoprotective serine protease protein C (PC). A protective effect of activated PC in diabetic nephropathy is established. We hypothesised that TM controls diabetic nephropathy independent of PC through its lectin-like domain by regulating complement. Diabetic nephropathy was analysed in mice lacking TM’s lectin-like domain (TMLeD/LeD) and controls (TMwt/wt). Albuminuria (290 μg/mg vs. 166 μg/mg, p=0.03) and other indices of experimental diabetic nephropathy were aggravated in diabetic TMLeD/LeDmice. Complement deposition (C3 and C5b-9) was markedly increased in glomeruli of diabetic TMLeD/LeDmice. Complement inhibition with enoxaparin ameliorated diabetic nephropathy in TMLeD/LeDmice (e.g. albuminuria 85 μg/mg vs. 290 μg/mg, p <0.001). In vitroTM’s lectin-like domain cell-autonomously prevented glucose-induced complement activation on endothelial cells and –notably –on podocytes. Podocyte injury, which was enhanced in diabetic TMLeD/LeDmice, was reduced following complement inhibition with enoxaparin. The current study identifies a novel mechanism regulating complement activation in diabetic nephropathy. TM’s lectin-like domain constrains glucose-induced complement activation on endothelial cells and podocytes and ameliorates albuminuria and glomerular damage in mice.

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Lectin-induced renal local complement activation is involved in tubular interstitial injury in diabetic nephropathy

Clinica Chimica Acta ◽

10.1016/j.cca.2018.03.033 ◽

2018 ◽

Vol 482 ◽

pp. 65-73 ◽

Cited By ~ 5

Author(s):

Jing-Min Zheng ◽

Xian-Guo Ren ◽

Zuan-Hong Jiang ◽

De-Jun Chen ◽

Wen-Jin Zhao ◽

...

Keyword(s):

Diabetic Nephropathy ◽

Complement Activation

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Complement Activation in Patients With Diabetic Nephropathy

Kidney International Reports ◽

10.1016/j.ekir.2017.10.005 ◽

2018 ◽

Vol 3 (2) ◽

pp. 302-313 ◽

Cited By ~ 12

Author(s):

Pascal Bus ◽

Jamie S. Chua ◽

Céline Q.F. Klessens ◽

Malu Zandbergen ◽

Ron Wolterbeek ◽

...

Keyword(s):

Diabetic Nephropathy ◽

Complement Activation

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The Lectin-Like Domain of Thrombomodulin Protects Against Diabetic Nephropathy by Inhibiting Complement Activation

Blood ◽

10.1182/blood.v116.21.654.654 ◽

2010 ◽

Vol 116 (21) ◽

pp. 654-654

Author(s):

Hongjie Wang ◽

Ilya Vinnikov ◽

Qianxing Zhou ◽

Thati Madhusudhan ◽

Khurrum Shahzad ◽

...

Keyword(s):

Endothelial Cells ◽

Diabetic Nephropathy ◽

Complement Activation ◽

Conflicts Of Interest ◽

Vascular Endothelial Cells ◽

Causative Role ◽

Coagulation Activation ◽

Histological Indices

Abstract Abstract 654 Introduction: Thrombomodulin (TM) is type 1 transmembrane glycoprotein predominately expressed on vascular endothelial cells. TM consists of distinct structural domains, which enable interaction with multiple ligands and thus modulation of coagulation, fibrinolysis, complement activation, inflammation, cell proliferation, and apoptosis. We have previously shown that TM protects against diabetic nephropathy (dNP) through activation of protein C (PC), which inhibits glomerular apoptosis. Recent studies showed that TM mediates cytoprotective effects independent of PC activation through it's lectin-like domain (LLD). The LLD directly interferes with complement activation and protect against arthritis. dNP is associated with an infiltration of inflammatory cells, enhanced cytokine production, and complement activation raising the question whether endothelial TM may protect against DN through a dual mechanism depending on (a) PC activation and (b) complement inhibition through the LLD. Methods: Experimental dNP was evaluated in mice with targeted deletion of the LLD of TM (TMLed/Led mice). Persistent hyperglycemia was induced using streptozotocin in TMLed/Led mice and in control wild type mice (wt). Subgroups of mice were treated with low molecular heparin (LMWH) to inhibit complement activation and coagulation activation, fondaparinux to inhibit coagulation activation, or treated with minocycline to inhibit glomerular apoptosis. After 28 weeks albuminuria was determined and mice were sacrificed to isolated tissues and blood samples for analyses. Results: Albuminuria, histological indices of diabetic nephropathy and glomerular C3 deposition were increased in diabetic wt mice and further increased in diabetic TMLed/Led mice. Only treatment with LMWH, but not with fondaparinux corrected the aggravated DN in TMLed/Led mice, despite equal anticoagulation in both groups. Glomerular complement depositions (immunohistochemistry) were significantly reduced following in vivo LMWH treatment, but no in fondaparinux treated mice. In vitro, endothelial cells expressing a TM mutant lacking the LLD had diminished capacity to bind and inactivate C3b and were thus sensitive to complement mediated cell lyses. Of note, apoptosis (TUNEL) and expression levels of apoptosis regulators (p53, Bax/Blc-2 ratio, Western) did not differ between untreated or LMWH/fondaparinux treated diabetic TMLed/Led mice, indicating that the protective effect of the LLD is independent of apoptosis inhibition. Consistently, inhibition of apoptosis with minocycline failed to normalize albuminuria or prevent histological indices of dNP in diabetic TMLed/Led mice. Likewise, we did not observe difference in HMGB-1 levels within the kidney or in plasma sample, and inhibition of HMGB-1 using sodium Tanshinon II asilate failed to reduce dNP in diabetic TMLed/Led mice. Discussion and Conclusion: We identify a novel pathway through which endothelial TM protects against dNP. TM protects against dNP by inhibiting complement activation through its LLD. This function is independent of the recently identified activated PC dependent inhibition of glomerular apoptosis. Thus, endothelial TM prevents dNP through two independent pathways. These results provide further experimental support for a causative role of endothelial dysfunction for DN. Disclosures: No relevant conflicts of interest to declare.

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P0998IDENTIFICATION OF DIFFERENTIALLY EXPRESSED GENES AND SIGNALING PATHWAYS IN DIABETIC NEPHROPATHY BY BIOINFORMATICS ANALYSIS

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfaa142.p0998 ◽

2020 ◽

Vol 35 (Supplement_3) ◽

Author(s):

Shumei Tang ◽

Xiangcheng Xiao

Keyword(s):

Diabetic Nephropathy ◽

Differentially Expressed Genes ◽

Complement Activation ◽

Molecular Mechanisms ◽

Bioinformatics Analysis ◽

Differentially Expressed ◽

Biological Processes ◽

Ppi Network ◽

String Database ◽

Molecular Functions

Abstract Background and Aims Diabetes has considerable negative impact on morbidity and mortality and causes huge social and economic burden. As one of the most serious microvascular complication of diabetes, diabetic nephropathy (DN) leads to a large population of end-stage renal disease in many countries. The pathogenesis of DN is always a hot topic and the underlying molecular events are not completely clear. Tubular injury plays an important role and may be the initial event. Although few therapeutic treatments could postpone the onset and development, the morbidity of DN remains high. More available therapeutic treatments are urgently needed as well as early stage diagnostic markers and more credible prognostic molecular markers. As a wide range application of high-throughput omics technology, various public network database platforms have included extensive transcriptomics data for deeper bioinformatics analysis. Integrating these data provides better understandings of molecular functions and biological processes. We performed integrated bioinformatics to recognize differentially expressed genes and discussed potential molecular mechanisms in DN. Method The expression profiles of GSE30529, GSE47184, GSE99325 and GSE104954 were downloaded from the Gene Expression Omnibus database. The four microarray datasets were centralized, integrated and performed a difference analysis. Next, differentially expressed genes (DEGs) were deeply analyzed by gene ontology annotation and enrichment analysis. STRING database was used to conducted a PPI network and Molecular Complex Detection (MCODE) software was used to identify central genes. Results The four files contain 63 tubular biopsy samples from patients with DN and 41 control tubule samples. We identified 18 target DEGs, C3, PROM1, LUM, CPA3, SERPINA3, ANXA1, CX3CR1, AGR2, CD48, REG1A, RARRES1, CYP24A1, C1R, CFB, CDH6, PVALB, GADD45B and KLK1. GO analysis indicated that biological processes of DEGs concentrate on proteolysis, inflammatory response, complement activation and regulation of complement activation. Main cellular components include extracellular exosome, extracellular region, extracellular space, blood microparticle, protein complex and plasma membrane. Molecular functions include calcium ion binding and serine-type endopeptidase activity. DEGs were found that maybe mainly involved in staphylococcus aureus infection, renin-angiotensin system, and complement and coagulation cascades by KEGG pathway analysis. The PPI network of DEGs were established by STRING database and one significant modules were identified by MCODE software. In addition, 3 hub genes, C3, CX3CR1 and ANXA1, were discerned from the PPI network. Conclusion To better clarify the underlying molecular mechanisms and provide more effective targets, this study screened DEGs and pathways in DN using bioinformatics analyses.

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