Fibrillary glomerulonephritis with small fibrils in a patient with the antiphospholipid antibody syndrome successfully treated with immunosuppressive therapy

Fibrillary Glomerulonephritis and DnaJ Homolog Subfamily B Member 9 (DNAJB9)

Fibrillary GN (FGN) is a rare glomerular disease that is diagnosed based on the presence of fibrils in glomeruli. The fibrils are typically noncongophilic, randomly oriented, and measure 12–24 nm. Traditionally, electron microscopy (EM) has been an important tool to aid in the diagnosis of FGN by identifying the fibrils and to distinguish it from other entities that could mimic FGN. However, recently DnaJ homolog subfamily B member 9 (DNAJB9) has emerged as both a specific and sensitive biomarker in patients with FGN. It allows prompt diagnosis and alleviates reliance on EM. DNAJB9 is a cochaperone of heat shock protein 70 and is involved in endoplasmic reticulum protein-folding pathways. But its role in the pathogenesis of FGN remains elusive. DNAJB9 may act as a putative antigen or alternatively it may secondarily bind to misfolded IgG in the glomeruli. These hypotheses need future studies to elucidate the role of DNAJB9 in the pathogenesis of FGN. The treatment regimen for FGN has been limited due to paucity of studies. Most patients receive combination immunosuppressive regimens. Rituximab has been studied the most in FGN and it may delay disease progression. Prognosis of FGN remains poor and 50% require dialysis within 2 years of diagnosis. Despite its poor prognosis in native kidneys, the rate of recurrence post-transplantation is low (20%) and patient as well as allograft outcomes are similar to patients without FGN.

Chronic thrombotic microangiopathy secondary to antiphospholipid syndrome, presenting with severe hypertension and chronic renal impairment

A 42-year-old woman was referred from a primary care centre for severe hypertension, stage 3A chronic kidney disease and proteinuria. This was associated with a significant obstetric history of pre-eclampsia during her previous two pregnancies. Secondary hypertension was suspected and autoimmune workup was positive for anticardiolipin IgG and lupus anticoagulant. A renal biopsy showed evidence of chronic thrombotic microangiopathy, with electron microscopy features suggestive of fibrillar glomerulonephritis. The diagnosis of antiphospholipid syndrome with antiphospholipid-associated nephropathy was made. She was started on anticoagulation with warfarin, and her hypertension was controlled with lisinopril and amlodipine with subsequent improvement in proteinuria. She remains on regular follow-up to monitor for possible development of malignancy or connective tissue disease.

Rare diagnosis in a patient with diabetes with nephrotic proteinuria

We report a 63-year-old man with well-controlled type 2 diabetes mellitus and hypertension, who presented with new onset nephrotic proteinuria and rapid deterioration in renal function. The atypical clinical presentation prompted us to consider a non-diabetic and non-hypertensive cause and to perform a renal biopsy. A diagnosis of fibrillarglomerulonephritis (FGn) was made based on electronic microscopy. Proteinuria remained in nephrotic range despite treatment with prednisolone, and renal function deteriorated. We suggest that other causes of proteinuria should be considered in patients with diabetes who present with the nephrotic syndrome when there is no other evidence of microvascular disease. We review the spectrum of fibrillar glomerulopathies including FGn, primary and secondary amyloidosis and immunotactoid glomerulonephritis.

Long-term kidney disease outcomes in fibrillary glomerulonephritis: a case series of 27 patients

BACKGROUND

Fibrillary glomerulonephritis (GN) is a rare disorder with poor renal prognosis. Therapeutic strategies, particularly the use of immunosuppressive drugs, are debated.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

27 adults with fibrillary GN referred to 15 nephrology departments in France between 1990 and 2011 were included. All patients were given renin-angiotensin system blockers and 13 received immunosuppressive therapy, including rituximab (7 patients) and cyclophosphamide (3 patients).

OUTCOMES & MEASUREMENTS

Clinical and histologic features of patients and kidney disease outcome. Renal response was defined as a >50% decrease in 24-hour proteinuria with <15% decline in estimated glomerular filtration rate (eGFR).

RESULTS

All patients presented with proteinuria, associated with nephrotic syndrome (41%), hematuria (73%), and hypertension (70%). Baseline median eGFR was 49 mL/min/1.73 m(2). Eight patients had a history of autoimmune disease and none had evidence of hematologic malignancy during follow-up. Light microscopic studies showed mesangial GN (70%), predominant pattern of membranous GN (19%), or membranoproliferative GN (11%). By immunofluorescence, immunoglobulin G (IgG) deposits (IgG4, 15/15; IgG1, 9/15) were polyclonal in 25 cases. Serum IgG subclass distribution was normal in the 6 patients tested. After a median 46-month follow-up, renal response occurred in 6 of 13 patients who received immunosuppressive therapy with rituximab (5 patients) or cyclophosphamide (1 patient). Of these, 5 had a mesangial or membranous light microscopic pattern, and median eGFR before therapy was 76 mL/min/1.73 m(2). In contrast, chronic kidney disease progressed in 12 of 14 patients who were not given immunosuppressive therapy, 10 of whom reached end-stage renal disease.

LIMITATIONS

Number of patients, retrospective study, use of multiple immunosuppressive regimens.

CONCLUSIONS

The therapeutic approach in fibrillary GN remains challenging. The place of immunosuppressive therapy, particularly anti-B-cell agents, needs to be assessed in larger collaborative studies.

Renal involvement in autoimmune connective tissue diseases

Connective tissue diseases (CTDs) are a heterogeneous group of disorders that share certain clinical presentations and a disturbed immunoregulation, leading to autoantibody production. Subclinical or overt renal manifestations are frequently observed and complicate the clinical course of CTDs. Alterations of kidney function in Sjögren syndrome, systemic scleroderma (SSc), auto-immune myopathies (dermatomyositis and polymyositis), systemic lupus erythematosus (SLE), antiphospholipid syndrome nephropathy (APSN) as well as rheumatoid arthritis (RA) are frequently present and physicians should be aware of that.In SLE, renal prognosis significantly improved based on specific classification and treatment strategies adjusted to kidney biopsy findings. Patients with scleroderma renal crisis (SRC), which is usually characterized by severe hypertension, progressive decline of renal function and thrombotic microangiopathy, show a significant benefit of early angiotensin-converting-enzyme (ACE) inhibitor use in particular and strict blood pressure control in general. Treatment of the underlying autoimmune disorder or discontinuation of specific therapeutic agents improves kidney function in most patients with Sjögren syndrome, auto-immune myopathies, APSN and RA.In this review we focus on impairment of renal function in relation to underlying disease or adverse drug effects and implications on treatment decisions.

Plasmapheresis leading to remission of refractory nephrotic syndrome due to fibrillary glomerulonephritis: a case report

INTRODUCTION

Fibrillary glomerulonephritis (FibGN) is characterized by extracellular deposition of Congo red-negative microfibrils within the glomerular mesangium and leads to gross proteinuria or nephrotic syndrome. After diagnosis of FibGN, end-stage renal disease occurs within four years in 50% of patients.

CASE PRESENTATION

A 36-year-old Caucasian woman with proteinuria and intermittent nephrotic syndrome due to FibGN intermittently received immunosuppressive therapies, including glucocorticoids, mycophenolate mofetil, and rituximab, for 10 years. However, disease remission was not achieved and progressive kidney injury developed. Ultimately, in stage IV of chronic kidney disease (Kidney Disease: Improving Global Outcomes), three cycles of plasmapheresis of five to seven sessions each were performed every three to four months, reducing steady-state proteinuria from 7 to less than 1 g/day. Here, plasmapheresis led to a remission of nephrotic syndrome associated with FibGN.

CONCLUSIONS

Plasmapheresis therapy is proposed as a further option for immunosuppressant-refractory FibGN.