Soluble fibrin formation in the mesangial area of IgA nephropathy

A high value of fibrinogen in immunoglobulin A nephropathy patients is associated with a worse renal tubular atrophy/interstitial fibrosis score

Purpose

The purpose of our study was to investigate the relationship between serum fibrinogen value and renal tubular atrophy/interstitial fibrosis in immunoglobulin A nephropathy patients with eGFR ≥90 ml/min/1.73 m².

Patients and Methods

Of 359 patients diagnosed with immunoglobulin A nephropathy after renal biopsy were enrolled in this retrospective study. Demographic, histopathological features, and clinical data were collected. The relationships among these factors were analyzed by using Student's t test, Mann‐Whitney U test, Kruskal‐Wallis test, Chi‐square test, or Fisher's exact test, where appropriate. The logistic regression analysis was performed to examine the independent risk factors.

Results

Of 176 immunoglobulin A nephropathy patients with eGFR ≥90 ml/min/1.73 m² were included in this study, and patients were classified into low fibrinogen (fibrinogen <304.6 mg/dl) and high fibrinogen (fibrinogen ≥304.6 mg/dl) groups, respectively. High fibrinogen groups had advanced age, a higher classification of renal tubular atrophy/interstitial fibrosis, and higher levels of systolic pressure, D‐dimer, 24 h urine protein quantitation, nag enzyme. Multivariate logistic analysis showed that fibrinogen (OR = 1.018) was significantly associated with tubular atrophy/interstitial fibrosis.

Conclusion

Among patients with immunoglobulin A nephropathy, the higher levels of fibrinogen and uric acid may mean a higher score of tubular atrophy/interstitial fibrosis, which suggests the renal biopsy should be performed for these patients as early as possible to defined pathological classification, even though there is no obvious abnormal change in the test of renal function.

Coagulation parameters are associated with the prognosis of immunoglobulin a nephropathy: a retrospective study

Background

Interstitial fibrosis/tubular atrophy (T) score is a known determinant of the progression of immunoglobulin A nephropathy (IgAN). Strong evidence indicates that the components of the coagulation system closely linked with fibrotic events have been highlighted in the kidney. However, whether the coagulation system can affect the renal outcome of IgAN remains unclear. Herein, we investigated the association of coagulation parameters and pathological phenotype of IgAN and their combined effects on the deterioration of renal function.

Methods

This retrospective study included N = 291 patients with biopsy-proven IgAN from May 2009 to April 2013 in the Second Xiangya Hospital. Clinical data, pathological features were collected, and the associations of coagulation parameters at biopsy, T score, and renal outcome were evaluated. T score indicated the degree of tubular atrophy or interstitial fibrosis. The renal outcome was defined as an end-stage renal disease (ESRD) or an irreversible 50% estimated glomerular filtration rate (eGFR) reduction.

Results

Shorter prothrombin time (PT) and the activated partial thromboplastin time (APTT) were significantly associated with T (both p < 0.001). PT (< 11.15 s) or APTT (< 29.65 s) had worse cumulative survival rate (p = 0.008, p = 0.027 respectively) and were significantly but not independently associated with a higher risk of renal outcome (p = 0.012, p = 0.032 respectively). In the combined analyses of PT, APTT, and T lesions, the odd ratios for the outcome were significantly higher in the presence of T with PT (< 11.15 s) or APTT (< 29.65 s).

Conclusion

Shorter PT and APTT are associated with an increased incidence of the T lesion and are additional factors that portend a poorer prognosis in IgAN. Monitoring coagulation function might be important when assessing the risk of progression. Additional studies exploring the molecular mechanism between coagulation and IgAN pathology are needed.

Roles of coagulation pathway and factor Xa in the progression of diabetic nephropathy in db/db mice

The active type of coagulation factor X (factor Xa) activates various cell-types through protease-activated receptor 2 (PAR2). We previously reported that a factor Xa inhibitor could suppress Thy-1 nephritis. Considering that fibrin deposition is observed in diabetic nephropathy as well as in glomerulonephritis, this study examined the roles of the coagulation pathway and factor Xa in the development of diabetic nephropathy using type 2 diabetic model mice. Diabetic (db/db) and normoglycemic (m+/m+) mice were immunohistochemically evaluated for their expression/deposition of PAR2, transforming growth factor (TGF)-β, fibrin, extracellular matrix (ECM) proteins, and CD31 at week 20. Significantly greater numbers of PAR2-positive cells and larger amounts of fibronectin, and collagen IV depositions were observed in the glomeruli of db/db mice than those in m+/m+ mice. Next, expression of PAR2 versus deposition of collagen IV and fibronectin was compared between week 20 and week 30, and the number of PAR2-positive cells in the glomeruli decreased in contrast with the increased accumulation of ECM proteins. In an intervention study, fondaparinux, a factor Xa inhibitor, was subcutaneously administered for ten weeks from week 10 to 20. Fondaparinux treatment significantly suppressed urinary protein, glomerular hypertrophy, fibrin deposition, expression of connective tissue growth factor, and ECM proteins deposition together with CD31-positive capillaries. These results suggest that coagulation pathway and glomerular PAR2 expression are upregulated in the early phase of diabetes, together with the increase of profibrotic cytokines expression, ECM proteins deposition and CD-31-positive vessels. Factor Xa inhibition may ameliorate glomerular neoangiogenesis and ECM accumulation in diabetic nephropathy.

Elevated tissue factor expression contributes to exacerbated diabetic nephropathy in mice lacking eNOS fed a high fat diet

BACKGROUND

 Human eNOS (NOS3) polymorphisms that lower its expression are associated with advanced diabetic nephropathy (DN), and the lack of eNOS accelerates DN in diabetic mice. Diabetes is associated with fibrin deposition. Lack of nitric oxide and fatty acids stimulates the NF-kB pathway, which increases tissue factor (TF).

OBJECTIVES

 To test the hypothesis that TF contributes to the severity of DN in the diabetic eNOS(-/-) mice fed a high-fat diet (HF).

METHODS

 We made eNOS(-/-) and wild-type mice diabetic with streptozotocin. Half of them were placed on HF.

RESULTS

 Blood glucose levels were not affected by either the diet or eNOS genotype. Lack of eNOS in the diabetic mice increased urinary albumin excretion, glomerulosclerosis, interstitial fibrosis, and glomerular basement membrane thickness. HF by itself did not affect DN in the wild-type mice, but significantly enhanced DN in eNOS(-/-) mice. More than half of diabetic eNOS(-/-) mice on HF died prematurely with signs of thrombotic complications. Diabetic kidneys contained fibrin and TF, and their levels were increased by the lack of eNOS and by HF in an additive fashion. The HF diet increased the kidney expression of inflammatory genes. The increase in TF preceded DN, and administration of an anti-mouse TF antibody to diabetic mice reduced the expression of inflammatory genes.

CONCLUSION

 Together, these data indicate a causal link between TF and the exacerbation of DN in eNOS(-/-) mice. The condition is significantly worsened by enhanced inflammatory responses to an HF diet via TF.

Tissue Factor and Factor V Involvement in Rat Peritoneal Fibrosis

Objective

Fibrin deposition on the peritoneum has been frequently observed in peritoneal fibrosis induced by long-term peritoneal dialysis. The present study was conducted to clarify the contribution of factor Xa through tissue factor and factor V expression in peritoneal fibrosis.

Methods

Wistar rats were intraperitoneally injected with chlorhexidine gluconate (CG) every day. For the interventional study, the factor Xa inhibitor fondaparinux was subcutaneously administered. After 28 days of CG injection, peritoneal specimens were examined by immunohistochemical analyses and in situ hybridization.

Results

The peritoneal submesothelial compact zone was observed to be markedly thicker in the CG-injected groups than in the normal group, and that thickness was dose dependent. Immunohistochemical study revealed massive fibrin, fibronectin, and type IV collagen depositions in the CG-injected groups, which was markedly higher than that in the normal group. Macrophage infiltration and staining for tissue factor, factor V, factor X, and protease-activated receptor-2 were intense in the CG-injected groups and negative/trace in the normal group. Tissue factor and factor V mRNAs were abundant in cells in the thickened peritoneum. A double-labeling experiment revealed that tissue factor was observed mainly in macrophages, and factor V was abundantly distributed in the fibrotic tissue together with macrophages. Fondaparinux treatment decreased the thickness of submesothelial fibrotic tissue, and size and number of CD31-positive vessels.

Conclusion

These results suggest that expression of tissue factor and factor V in infiltrated macrophages, together with factor X deposition, may progress angiogenesis and accumulation of extracellular matrix components, partly via profibrotic and procoagulant mechanisms in the peritoneum after inflammatory stimulation.