Expression of macrophage markers in cryoglobulinemic glomerulonephritis - a possible role of CXCL9

The Clinical and Histopathological Feature of Renal Manifestation of TAFRO Syndrome

Introduction

Thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, and organomegaly (TAFRO) syndrome is a severe subtype of idiopathic multicentric Castleman’s disease, characterized by thrombocytopenia, anasarca, fever, reticulin myelofibrosis, and organomegaly. Renal complication of this disease can be life-threatening and sometimes requires hemodialysis, but it has not been elucidated in detail.

Methods

Case-series was designed to evaluate the renal histology of patients with TAFRO syndrome treated at our hospital.

Results

Seven patients were eligible to the criteria. All of them had severe diuretic-resistant anasarca and 6 of 7 had mild proteinuria (<1 g daily). On light microscopy, all patients showed glomerular endotheliopathy characterized by endothelial cell swelling and a double contour of the glomerular basement membrane with mesangiolysis or mesangial loosening. Immunofluorescent staining and electron microscopy did not detect immune deposits in any patient. Electron microscopy revealed endothelial cell swelling with diffuse expansion of the subendothelial space, loss of mesangial architecture, and loss of endothelial cell fenestrations. Treatment with glucocorticoids and molecular-targeting agents, including tocilizumab and rituximab, improved renal dysfunction and anasarca. In 4 of 7 patients with persistent thrombocytopenia, hemorrhagic events occurred despite platelet transfusion or thrombopoietin receptor antagonist therapy.

Conclusion

Severe diuretic-resistant anasarca with mild proteinuria and severe glomerular endotheliopathy were common characteristics of renal dysfunction due to TAFRO syndrome. In addition, endothelial changes mediated via interleukin (IL)-6 and vascular endothelial growth factor (VEGF) that lead to vascular hyperpermeability and water leakage might contribute to anasarca, because molecular-targeting therapy directed against IL-6 or VEGF improved renal dysfunction and severe endothelial damage.

Serial Manifestation of Acute Kidney Injury and Nephrotic Syndrome in a Patient with TAFRO Syndrome

A 76-year-old woman suddenly developed anasarca and a fever, and an examination revealed thrombocytopenia, reticulin fibrosis, and acute kidney injury, yielding the diagnosis of thrombocytopenia, anasarca, fever, reticulin fibrosis, organomegaly (TAFRO) syndrome. Renal replacement therapy and steroid treatment were soon started. Her proteinuria was minor at first; however, once the kidney function improved, nephrotic syndrome occurred. A kidney biopsy showed membranoproliferative glomerulonephritis-like glomerulopathy with massive macrophage infiltration. Although kidney dysfunction is often observed in TAFRO syndrome patients, its detailed mechanism is unclear. This case suggests that TAFRO syndrome involves both acute kidney injury with minor proteinuria and nephrotic syndrome, and these disorders can develop serially in the same patient.

ABIN1 Determines Severity of Glomerulonephritis via Activation of Intrinsic Glomerular Inflammation

Transcription factor NF-κB regulates expression of numerous genes that control inflammation and is activated in glomerular cells in glomerulonephritis (GN). We previously identified genetic variants for a NF-κB regulatory, ubiquitin-binding protein ABIN1 as risk factors for GN in systemic autoimmunity. The goal was to define glomerular inflammatory events controlled by ABIN1 function in GN. Nephrotoxic serum nephritis was induced in wild-type (WT) and ubiquitin-binding deficient ABIN1[D485N] mice, and renal pathophysiology and glomerular inflammatory phenotypes were assessed. Proteinuria was also measured in ABIN1[D485N] mice transplanted with WT mouse bone marrow. Inflammatory activation of ABIN1[D472N] (D485N homolog) cultured human-derived podocytes, and interaction with primary human neutrophils were also assessed. Disruption of ABIN1 function exacerbated proteinuria, podocyte injury, glomerular NF-κB activity, glomerular expression of inflammatory mediators, and glomerular recruitment and retention of neutrophils in antibody-mediated nephritis. Transplantation of WT bone marrow did not prevent the increased proteinuria in ABIN1[D845N] mice. Tumor necrosis factor-stimulated enhanced expression and secretion of NF-κB-targeted proinflammatory mediators in ABIN1[D472N] cultured podocytes compared with WT cells. Supernatants from ABIN1[D472N] podocytes accelerated chemotaxis of human neutrophils, and ABIN1[D472N] podocytes displayed a greater susceptibility to injurious morphologic findings induced by neutrophil granule contents. These studies define a novel role for ABIN1 dysfunction and NF-κB in mediating GN through proinflammatory activation of podocytes.

Reduction in Renal Ischemia-Reperfusion Injury in Mice by a Phosphoinositide 3-Kinase p110gamma-Specific Inhibitor

BACKGROUND

Although renal ischemia-reperfusion injury (IRI) can cause delayed graft function, a targeted therapy is not yet available. Because phosphoinositide 3-kinases (PI3K) p110γ and p110δ play important roles in immune cell migration and function, we investigated the effects of PI3K p110γ- and p110δ-specific inhibitors in a murine renal IRI model.

METHODS

Renal function was assessed by serum creatine and hematoxylin-eosin staining. Immune cell migration was assessed by flow cytometry and an in vitro cell migration assay using Transwell plates. Gene expression analysis and a multiplex cytokine/chemokine assay were performed to find cytokines/chemokines whose expression was upregulated in renal IRI and affected by p110γ-specific inhibitor.

RESULTS

The PI3K p110γ-specific inhibitor, but not p110δ-specific inhibitor, significantly reduced serum creatine levels and acute tubular necrosis. These were accompanied by reduced infiltration of B cells and reduced expression of CXCL9, a CXCR3 ligand, suggesting that p110γ plays an important role in B-cell migration toward injured kidneys. An in vitro cell migration assay revealed for the first time that B-cell migration to injured kidney cells and to CXCL9 requires p110γ.

CONCLUSIONS

p110γ-specific inhibitor ameliorates renal IRI by reducing necrosis and immune cell migration. This inhibitor may have the potential to reduce renal graft failure caused by renal IRI.