Secondary membranoproliferative glomerulonephritis

Understanding the relationship between HCV infection and progression of kidney disease

Hepatitis C virus (HCV) can cause a range of kidney diseases. HCV is the primary cause of mixed cryoglobulinaemia, which leads to cryoglobulinaemic vasculitis and cryoglobulinaemic glomerulonephritis (GN). Patients with acute cryoglobulinaemic vasculitis often exhibit acute kidney disease due to HCV infection, which typically progresses to acute kidney injury (AKI). HCV also increases the risk of chronic kidney disease (CKD) and the likelihood of developing end-stage renal disease (ESRD). Currently, direct-acting antiviral agents (DAAs) can be used to treat kidney disease at different stages. This review focuses on key findings regarding HCV and kidney disease, discusses the impact of DAAs, and highlights the need for further research and treatment.

Membranoproliferative Glomerulonephritis Pattern of Injury

Membranoproliferative glomerulonephritis (MPGN) is no longer a disease but a pattern of injury in various diseases. Characterized by electron-dense deposits, mesangial proliferation, and duplication of the glomerular basement membrane, MPGN was previously classified by findings seen by electron microscopy. However, recognizing complement dysfunction in relation to cases with the MPGN pattern of injury substantially changed our view of its pathogenesis. A new classification, including immune complex-mediated and complement-mediated MPGN, has become preferable and has been adopted by international guidelines. Despite these advancements, accurate diagnosis of MPGN remains a clinical challenge, given the pathological and clinical similarities between immune complex-mediated and complement-mediated MPGN. Additional testing, such as molecular and genetic testing, is often necessary. Here, we will summarize our current understanding of the MPGN pattern of injury from a pathology perspective as an introductory article in the following chapters.

[Influenza A: H1N1 post-viral membranoproliferative glomerulonephritis occurring in aggressive systemic mastocytosis: Case report and literature review]

Systemic mastocytosis is characterised by tissular infiltration and a cytokine storm due to mast cells excessive proliferation and activation. Herein, we report an extraordinary case of AH1N1 influenza post-viral glomerulonephritis occurring in the course of an aggressive systemic mastocytosis with an associated hematological neoplasm. Because of a multisystemic involvement including the liver and lungs, we treated mastocytosis with midostaurin (multiple inhibitor of kinase protein), anti H1/H2 blockers and dexamethasone as first line treatment. One month later and despite vaccination, he developed a severe acute lung injury with respiratory distress due to AH1N1 influenza in association with the nephrotic syndrome. Kidney biopsy disclosed a membranoproliferative glomerulonephritis that was successfully treated with mycophenolate mofetil. Only a few cases of influenza post-viral or post-vaccination glomerulonephritis are documented in the medical literature. This is an exceptional association of uncommon conditions occurring within only a few months in the same patient.

Immune Thrombocytopenic Purpura Complicated by Hepatitis C Virus-related Membranoproliferative Glomerulonephritis after Rituximab Therapy

We herein report the case of a 54-year-old Japanese man with hepatitis C virus (HCV)-related membranoproliferative glomerulonephritis (MPGN), which developed at the time of relapse of immune thrombocytopenic purpura (ITP) after rituximab therapy. Antiviral therapy for HCV led to the improvement of both MPGN and ITP. Rituximab therapy may have contributed to the exacerbation of HCV infection and induced the development of HCV-related MPGN and the relapse of ITP. Our case suggested that HCV treatment should be prioritized over rituximab therapy for HCV-positive patients with ITP and that antiviral therapy for HCV may be effective for treating ITP itself.

Immunotactoid Glomerulopathy with Nontuberculous Mycobacterial Infection: A Novel Association

A 70-year-old woman underwent a renal biopsy due to nephrotic syndrome. She had suffered from nontuberculous mycobacterial infection (NTM) for 14 years. The patient was diagnosed as having membranoproliferative glomerulonephritis (MPGN) type 3 and immunoglobulin (Ig)-associated MPGN based upon LM/erythromycin and IF findings, respectively. In high-magnification imaging, electron-dense deposits showed immunotactoid glomerulopathy (ITG). There was no evidence of hematological cancer, and the patient improved after receiving treatments for NTM. To the best of our knowledge, this patient is the first to show an association between ITG and NTM. Although ITG is generally considered as related to lymphoproliferative disease, it is suggested that ITG is driven by bacterial infection and is a potential outcome of Ig-associated MPGN.

Poststreptococcal acute glomerulonephritis in a girl with renal cell carcinoma: possible pathophysiological association

The severity of the poststreptococcal acute glomerulonephritis is considered to be modulated by the immune response of each individual, although there had been few reports regarding specific factors. Renal cell carcinoma is a cancer frequently associated with paraneoplastic syndrome, characterized by fever, leukocytosis, elevated cytokines, and elevated hormone levels. All of these symptoms resolve after tumor resection. A girl with renal cell carcinoma developed renal failure rapidly, which resolved promptly right after nephrectomy for the carcinoma. She was diagnosed as having poststreptococcal acute glomerulonephritis according to the results of pathological and serological examinations. In addition, elevated serum interleukin-6 level before the surgery was detected. Six and a half years after the diagnosis, the patient's renal function was within normal range and she was tumor free. Because of the quick resolution of her renal dysfunction after the nephrectomy, paraneoplastic syndrome induced by renal cell carcinoma seemed to play a key role in the accentuation of poststreptococcal acute glomerulonephritis.

Clinical and Pathophysiological Insights Into Immunological Mediated Glomerular Diseases in Childhood

The kidney is often the target of immune system dysregulation in the context of primary or systemic disease. In particular, the glomerulus represents the anatomical entity most frequently involved, generally as the expression of inflammatory cell invasion or circulant or in situ immune-complex deposition. Glomerulonephritis is the most common clinical and pathological manifestation of this involvement. There are no universally accepted classifications for glomerulonephritis. However, recent advances in our understanding of the pathophysiological mechanisms suggest the assessment of immunological features, biomarkers, and genetic analysis. At the same time, more accurate and targeted therapies have been developed. Data on pediatric glomerulonephritis are scarce and often derived from adult studies. In this review, we update the current understanding of the etiologic events and genetic factors involved in the pathogenesis of pediatric immunologically mediated primitive forms of glomerulonephritis, together with the clinical spectrum and prognosis. Possible new therapeutic targets are also briefly discussed.

Chronic Chagastic cardiomyopathy associated with membranoproliferative glomerulonephritis: Report of an autopsy case

An autopsy case of chronic Chagas disease, a debilitating disorder caused by persistent infection by protozoa, Trypanosoma cruzi (Tr. cruzi), is reported. The patient was a 73-year-old Brazilian woman of Japanese descent, who had emigrated to Japan at the age of about 40 years. She died of chronic cardiac insufficiency about 8 years after the onset of cardiac symptoms. At autopsy, the heart showed typical features of chronic Chagastic cardiomyopathy: chronic lymphocytic myocarditis with extensive fibrosis and the formation of an apical aneurysm. The pathogenic protozoa were not detected in the cardiac tissue. The kidney showed typical features of membranoproliferative glomerulonephritis (MPGN). On the basis of experimental data which suggested that chronic infection of Tr. cruzi could elicit immune complex-mediated glomerulonephritis, we considered that the chronic persistent infection by Tr. cruzi contributed to the pathogenesis of MPGN in this patient.

A case of Graves' disease associated with membranoproliferative glomerulonephritis and leukocytoclastic vasculitis

Background The association of hyperthyroidism with renal disease is very rare and the importance of timely clinical recognition cannot be overemphasized. Case presentation An 11-year-old girl presented with gastrointestinal symptoms while hypertension, edema and abdominal pain were noticed on clinical examination. Laboratory investigation revealed: hemoglobin 9.4 (11.5-15.5) g/dL, total white cell count 16 (4.5-12)×109/L, platelets 247 (150-450)×109/L, C-reactive protein (CRP) 31.8 (<5) mg/L, blood urea nitrogen (BUN) 126 (13-43) mg/dL, creatinine 0.98 (0.53-0.79) mg/dL, albumin 25 (35-52) g/dL, complement factor C3 0.7 (0.9-1.8) g/L, complement factor C4 0.1 (0.1-0.4) g/L, tri-iodothyronine 6.5 (2.5-5.2) pg/mL, free thyroxine 2.4 (1-1.7) ng/dL, thyroid stimulating hormone (TSH) <0.02 (0.5-4.3) mU/L. Urinalysis showed nephrotic range proteinuria. Renal function deteriorated necessitating hemodialysis (HD). A renal biopsy revealed an immune complex-mediated membranoproliferative glomerulonephritis (MPGN). Elevated thyroid hormones and suppressed TSH levels with elevated thyroperoxidase antibodies and thyroid stimulating immunoglobulins confirmed the diagnosis of Graves' disease. Corticosteroids were commenced and eventually thiamazole was added with gradual improvement of renal function, cessation of HD and discharge from the hospital. Conclusions Graves' disease complicated by MPGN is extremely rare, but can cause life-threatening complications.

C3 Glomerulopathy

Recent advances in our understanding of the disease pathology of membranoproliferative glomerulonephritis has resulted in its re-classification as complement C3 glomerulopathy (C3G) and immune complex-mediated glomerulonephritis (IC-GN). The new consensus is based on its underlying pathomechanism, with a key pathogenetic role for the complement alternative pathway (AP), rather than on histomorphological characteristics. In C3G, loss of AP regulation leads to predominant glomerular C3 deposition, which distinguishes C3G from IC-GN with predominant immunoglobulin G staining. Electron microscopy further subdivides C3G into C3 glomerulonephritis and dense deposit disease depending on the presence and distribution pattern of electron-dense deposits within the glomerular filter. Mutations or autoantibodies affecting the function of AP activators or regulators, in particular the decay of the C3 convertase (C3 nephritic factor), have been detected in up to 80 % of C3G patients. The natural outcome of C3G is heterogeneous, but 50 % of patients progress slowly and reach end-stage renal disease within 10-15 years. The new classification not only marks significant advancement in the pathogenic understanding of this rare disease, but also opens doors towards more specific treatment with the potential for improved outcomes.

Reclassification of membranoproliferative glomerulonephritis: Identification of a new GN: C3GN

This review revises the reclassification of the membranoproliferative glomerulonephritis (MPGN) after the consensus conference that by 2015 reclassified all the glomerulonephritis basing on etiology and pathogenesis, instead of the histomorphological aspects. After reclassification, two types of MPGN are to date recognized: The immunocomplexes mediated MPGN and the complement mediated MPGN. The latter type is more extensively described in the review either because several of these entities are completely new or because the improved knowledge of the complement cascade allowed for new diagnostic and therapeutic approaches. Overall the complement mediated MPGN are related to acquired or genetic cause. The presence of circulating auto antibodies is the principal acquired cause. Genetic wide association studies and family studies allowed to recognize genetic mutations of different types as causes of the complement dysregulation. The complement cascade is a complex phenomenon and activating factors and regulating factors should be distinguished. Genetic mutations causing abnormalities either in activating or in regulating factors have been described. The diagnosis of the complement mediated MPGN requires a complete study of all these different complement factors. As a consequence, new therapeutic approaches are becoming available. Indeed, in addition to a nonspecific treatment and to the immunosuppression that has the aim to block the auto antibodies production, the specific inhibition of complement activation is relatively new and may act either blocking the C5 convertase or the C3 convertase. The drugs acting on C3 convertase are still in different phases of clinical development and might represent drugs for the future. Overall the authors consider that one of the principal problems in finding new types of drugs are both the rarity of the disease and the consequent poor interest in the marketing and the lack of large international cooperative studies.

Understanding the complement-mediated glomerular diseases: focus on membranoproliferative glomerulonephritis and C3 glomerulopathies

An enhanced understanding of the role of complement in the pathogenesis of membranoproliferative glomerulonephritis has led to reclassification of the latter into immunoglobulin-mediated and non-immunoglobulin-mediated disease. The new classification schema resulted in improved diagnostic clinical algorithms, while it brought into light again the diseases, which are characterized by the presence of glomerular deposits, composed predominantly by C3, in the absence of significant amounts of immunoglobulins in renal biopsy, namely, C3 glomerulopathies (dense deposit disease and C3 glomerulonephritis). Despite the lack of randomized controlled trials following the advances in the understanding of the pathogenetic pathways involved in membranoproliferative glomerulonephritis, it is important that the new mechanistic approach has opened new roads for the exploration and discovery of targeted therapies.

Membranoproliferative glomerulonephritis recurrence after kidney transplantation: using the new classification

Background

Membranoproliferative glomerulonephritis (MPGN) is an uncommon glomerular disorder that may lead to end stage renal disease (ESRD). With new understanding of the disease pathogenesis, the classical classification as MPGN types I, II, III has changed. Data on post-transplant MPGN, in particular with the newly refined classification, is limited. We present our center’s experience of MPGN after kidney transplantation using the new classification.

Methods

This is a retrospective study of 34 patients with ESRD due to MPGN who received 40 kidney transplants between 1994 and 2014. We reviewed the available biopsies’ data using the new classification. We assessed post transplantation recurrence rate, risk factors of recurrence, the response to therapy and allografts’ survival.

Results

Median time of follow up was 5.3 years (range 0.5–14 years). Using the new classification, we found that pre-transplant MPGN disease was due to immune complex-mediated glomerulonephritis (ICGN) in 89 % of cases and complement-mediated glomerulonephritis (CGN) in 11 %. Recurrence was detected in 18 transplants (45 %). Living related allografts (P = 0.045), preemptive transplantations (P = 0.018), low complement level (P = 0.006), and the presence of monoclonal gammopathy (P = 0.010) were associated with higher recurrence rate in ICGN cases. Half of the patients with recurrence lost their allografts. The use of ACEi/ARB was associated with a trend toward less allograft loss.

Conclusions

MPGN recurs at a high rate after kidney transplantation. The risk of MPGN recurrence increases with preemptive transplantation, living related donation, low complement level, and the presence of monoclonal gammopathy. Recurrence of MPGN leads to allograft failure in half of the cases.

A case of membranoproliferative glomerulonephritis and AA amyloidosis complicated with pulmonary nontuberculous mycobacterial infection

A 75-year-old man was diagnosed with pulmonary nontuberculous mycobacterial (NTM) infection in February 2005 and was treated with rifampicin, ethambutol, and clarithromycin. However, the infection was resistant to treatment, and his chest radiograph showed an abnormality that gradually seemed to aggravate. The patient's sputum was positive for Mycobacteria. Moreover, the patient had dyspnea and an underlying chronic inflammation in the lungs. He visited our hospital because of dyspnea and leg edema in June 2011. Laboratory evaluation on admission revealed proteinuria (6 g/day) and decreased serum total protein (5.8 g/dL) and albumin (1.6 g/dL) levels, indicating nephrotic syndrome. Percutaneous renal biopsy revealed membranoproliferative glomerulonephritis (MPGN) in the acute stage and AA amyloidosis of mild degree. AA amyloidosis was also diagnosed histologically on gastric and colonic biopsy, in addition to renal biopsy. His renal function decreased gradually, and therefore, he underwent hemodialysis therapy in January 2012. However, his gastrointestinal-related symptoms persisted, and his appetite diminished, because of which he had become severely malnourished; he died 8 months later. This is a rare case of a patient with two different renal lesions (MPGN and AA amyloidosis) complicated with NTM. Our case suggests that MPGN and amyloidosis should be considered in elderly patients with nephrotic syndrome onset and chronic inflammation.

Membranoproliferative glomerulonephritis in patients with chronic venous catheters: a case report and literature review

Chronic indwelling catheters have been reported to be associated with membranoproliferative glomerulonephritis (MPGN) via the activation of the classical complement pathway in association with bacterial infections such as coagulase negative staphylococcus. We herein provide supporting evidence for the direct causal relationship between chronic catheter infections and MPGN via a case of recurrent MPGN associated with recurrent catheter infections used for total parenteral nutrition (TPN) in a man with short gut syndrome. We also present a literature review of similar cases and identify common clinical manifestations that may serve to aid clinicians in the early identification of MPGN associated with infected central venous catheterization or vice versa. The importance of routine monitoring of kidney function and urinalysis among patients with chronic central venous catheterization is highlighted as kidney injury may herald or coincide with overtly infected chronic indwelling central venous catheters.

[C3 glomerulopathy]

C3 glomerulopathy is an heterogeneous group of glomerular diseases associated with acquired or genetic abnormalities of complement alternative pathway (AP) components. It is characterized by predominant C3 deposits in the mesangium and along the glomerular basement membrane (GBM). Presenting features comprise proteinuria (sometimes with nephritic syndrome), haematuria, hypertension and renal failure. C3 glomerulopathy have a poor renal prognosis with progression to end stage renal disease (ESRD) in 50% of cases during the first decade after initial presentation. Moreover, C3 deposits recur in most of cases after renal transplantation. Patients frequently have low serum C3 level attributed to the activation of the alternative pathway of complement. Animal models have confirmed the role of excessive C3 activation in the pathogenesis of C3 glomerulopathy. To date, the optimal treatment remains unknown. It is currently based on the use of angiotensin-converting-enzyme inhibitors (ACEI) and angiotensin II-receptor blockers (ARB), sometimes associated with immunosuppressive therapy. Blockade of C5a release with eculizumab, a monoclonal anti-C5 antibody, may be of particular interest in the treatment of C3G.

Membranoproliferative glomerulonephritis associated with autoimmune diseases

Membranoproliferative glomerulonephritis (MPGN) has been classified based on its pathogenesis into immune complex-mediated and complement-mediated MPGN. The immune complex-mediated type is secondary to chronic infections, autoimmune diseases or monoclonal gammopathy. There is a paucity of data on MPGN associated with autoimmune diseases. We reviewed the Mayo Clinic database over a 10-year period and identified 12 patients with MPGN associated with autoimmune diseases, after exclusion of systemic lupus erythematosus. The autoimmune diseases included rheumatoid arthritis, primary Sjögren's syndrome, undifferentiated connective tissue disease, primary sclerosing cholangitis and Graves' disease. Nine of the 12 patients were female, and the mean age was 57.9 years. C4 levels were decreased in nine of 12 patients tested. The serum creatinine at time of renal biopsy was 2.2 ± 1.0 mg/dl and the urinary protein was 2,850 ± 3,543 mg/24 h. Three patients required dialysis at the time of renal biopsy. Renal biopsy showed an MPGN in all cases, with features of cryoglobulins in six cases; immunoglobulin (Ig)M was the dominant Ig, and both subendothelial and mesangial electron dense deposits were noted. Median follow-up was 10.9 months. Serum creatinine and proteinuria improved to 1.6 ± 0.8 mg/dl and 428 ± 677 mg/24 h, respectively, except in 3 patients with end-stage renal disease. In summary, this study describes the clinical features, renal biopsy findings, laboratory evaluation, treatment and prognosis of MPGN associated with autoimmune diseases.

Update on membranoproliferative GN

Membranoproliferative GN represents a pattern of injury seen on light microscopy. Historically, findings on electron microscopy have been used to further subclassify this pathologic entity. Recent advances in understanding of the underlying pathobiology have led to a proposed classification scheme based on immunofluorescence findings. Dysregulation of the complement system has been shown to be a major risk factor for the development of a membranoproliferative GN pattern of injury on kidney biopsy. Evaluation and treatment of this complex disorder rest on defining the underlying mechanisms.

Membranoproliferative glomerulonephritis and circulating cryoglobulins

Background

Previous studies on membranoproliferative glomerulonephritis (MPGN) and cryoglobulinemic glomerulopathy (CG) were based upon case series that were performed before hepatitis C virus (HCV) infection was routinely investigated. Therefore, it remains unknown how far HCV contributes to MPGN or CG, and there have only been a few reports about HCV-negative idiopathic MPGN.

Patients and methods

Thirty-five patients with MPGN diagnosed by renal biopsy who underwent examination for HCV infection at our institute between 1990 and 2008 were recruited for this study. Patients with HCV infection at presentation were included, but patients with complications such as underlying lymphoproliferative disorders, autoimmune diseases like lupus nephritis, infection, and liver disease due to hepatitis B virus or alcohol abuse were excluded. A total of 35 patients were enrolled and they were divided into two groups according to the presence/absence of circulating cryoglobulins (cryo). The 23 patients who had cryo-negative and HCV-negative idiopathic MPGN were divided into subgroups with type 1 and type 3 disease.

Results

In the cryo-positive group (n = 9), 7 patients were positive for HCV infection, while 2 patients were negative. In the cryo-negative group (n = 26), 3 patients were positive for HCV infection, while 23 patients were negative (idiopathic MPGN). Compared with the cryo-negative group, the cryo-positive group had several characteristics such as more severe thrombocytopenia, higher serum immunoglobulin (Ig)G and IgM levels, lower levels of hemolytic complement (CH50) and complement component (C)4, predominant IgM staining, and type 1 histology. Patients with cryo-negative and HCV-negative ‘idiopathic’ MPGN showed predominant staining for IgG in both type 1 and type 3 cases, unlike the predominant staining for IgM in the cryo-positive group. Compared with type 3 cases, type 1 cases had a younger age, lower levels of CH50, C3 and C4, and less proteinuria. In the cryo-positive group, 4 patients (44.4 %) died, with death from B cell lymphoma and liver failure in 2 patients each, while 1 patient (8 %) developed end-stage renal failure requiring dialysis. In contrast, all patients in the cryo-negative group remained alive during follow-up, although 4 patients (2 type 1 cases and 2 type 3 cases) required dialysis.

Conclusion

Cryo-positive MPGN shows a close relationship with HCV infection and IgM, resulting in a poor prognosis. Cryo-negative and HCV-negative idiopathic MPGN has a close relationship with IgG staining, and type 1 cases feature characteristics such as a younger age, more severe hypocomplementemia, and less proteinuria than in type 3 cases.

A case of membranoproliferative glomerulonephritis developed over twenty years with three different findings of renal pathology

A 31-year-old woman with proteinuria, hypocomplementemia, rheumatoid factor, and high serum polyclonal IgM concentration was admitted to our hospital for renal biopsy. She had a past history of two renal biopsies. When she was 12 years old, she developed proteinuria, microscopic hematuria, and hypocomplementemia. She was diagnosed as having 'IgM nephropathy' based on minor glomerular abnormalities as determined by light microscopy and IgM and C3 deposition in the mesangial region by immunofluorescence microscopy at the first biopsy. Despite corticosteroid treatment, her proteinuria did not improve and she discontinued regular outpatient checkups. When she was 29 years old and pregnant, she developed preeclampsia and, after delivery, a second renal biopsy was implemented. She was diagnosed as having progressed 'IgM nephropathy' with endotheliosis induced by preeclampsia. She was treated with angiotensin II receptor blocker and her proteinuria diminished; however, 1 year after the delivery, she developed proteinuria again, along with microscopic hematuria and hypocomplementemia. A third renal biopsy was conducted at 31 years of age and she was diagnosed as having membranoproliferative glomerulonephritis (MPGN) type I on the basis of diffuse mesangial proliferation, endocapillary hypercellularity with double contour of the capillary wall, and lobular formation in glomeruli, as determined by light microscopy. Immunofluorescence staining demonstrated deposits of C3, C4, C1q, and IgM in the mesangial region and capillary wall. She underwent corticosteroid therapy followed by normalization of urinalysis and serum complement level. Although she had initially been diagnosed with 'IgM nephropathy', she was finally diagnosed with secondary MPGN and was successfully treated by corticosteroid therapy.

Membranoproliferative glomerulonephritis and inflammatory pseudotumour of the spleen

Inflammatory pseudotumour is a rare condition that can affect various organs. The clinical and histologic appearance of the pseudotumour may mimic haematological, lymphoproliferative, paraneoplastic or malignant processes. A previously healthy 39-year-old man presented with nephrotic syndrome. He had a history of headaches, nausea and swollen ankles. Computed tomography of the abdomen revealed a 6-cm mass in the spleen. Following a renal biopsy, a diagnosis of membranoproliferative glomerulonephritis (MPGN) type I was made. Splenectomy was performed and the examination revealed a mixed population of lymphocytes with predominantly T-cells, B-cells and lymphoplasmacytoid cells. Immunostaining confirmed that the small cells were mostly T-cells positive for all T-cell markers including CD2, CD3, CD4, CD5, CD7 and CD8. A diagnosis of inflammatory pseudotumour was established. The removal of the spleen was followed by remission of glomerulonephritis, but it was complicated by a subphrenic abscess and pneumonia. This association between an inflammatory pseudotumour of the spleen and MPGN has not been previously described. Abnormal immune response due to the inflammation leading to secondary glomerulonephritis might be the main pathogenic mechanism.

Borrelia and nephropathy: cryoglobulinaemic membranoproliferative glomerulonephritis responsive to doxycyclin in active Lyme disease

The association of membranoproliferative glomerulonephritis (MPGN) with Lyme borreliosis has only been reported for the C1q-negative subtype. A 64-year-old male presenting with rising creatinine, nephrotic syndrome and monoarthritis few months after a tick bite was noted to have mixed cryoglobulinaemia, a positive borrelia western blot and 'full-house' pattern MPGN with interstitial granuloma. Findings resolved with prednisolone and doxycyclin therapy. The histology is consistent with MPGN secondary to cryoglobulinaemia, which has most likely been caused by borrelia infection. 'Full-house' pattern MPGN may result from Lyme borreliosis through cryoglobulinaemia and may be treated successfully with the appropriate antibiotic therapy.

Idiopathic membranoproliferative glomerulonephritis: does it exist?

When membranoproliferative glomerulonephritis (MPGN) was first delineated as a discrete clinico-pathological entity more than a half-century ago, most cases were regarded as idiopathic (or primary) in nature. Advances in analysis of pathogenetic mechanisms and etiologies underlying the lesion of MPGN have radically altered the prevalence of the truly idiopathic form of MPGN. In addition, MPGN as a category among renal biopsies showing glomerulonephritis has diminished over time. In the modern era, MPGN is mainly classified morphologically on the basis of immunoglobulin (Ig; monoclonal or polyclonal) and complement (C3 only or combined with Ig) deposition and secondarily on the basis of its appearance on ultra-structural examination. Idiopathic MPGN is a diagnosis of exclusion, at least in many adults and a portion of children, and a systematic approach to evaluation will often uncover a secondary cause, such as an infection, autoimmune disease, monoclonal gammopathy, neoplasia, complement dysregulation or a chronic thrombotic microangiopathy. Idiopathic MPGN remains an 'endangered species' after its separation from these known causes.

Recurrent membranoproliferative glomerulonephritis after second renal graft treated with plasmapheresis and rituximab

We present a case of a 45-year-old man who suffered from idiopatic membranoproliferative glomerulonephritis (MPGN) in the native kidney that relapsed after his first and second renal grafts. The patient was diagnosed in 1990 with lobular MPGN type I, receiving his first renal graft in 1996. In 2001, a biopsy showed recurrence of MPGN type I (rMPGN). He underwent a second renal graft in 2008. In January 2010, he experienced increased proteinuria and creatinine. Upon electron microscopy of a renal graft biopsy we diagnosed a new rMPGN. At the time of the biopsy, complement levels were normal, although C3 and C4 decreased further. We administered 12 plasmapheresis (PP) sessions and four doses of rituximab. Due to persistent renal impairment, we performed a new biopsy 3 months later, showing less severity of the acute lessions. He received a new cycle of treatment (PP+rituximab). One year later, his renal function was stable with a creatinine ranging between 2 and 2.5 mg/dL and a protein/creatinine ratio less than 1 mg/mg. We concluded that the treatment stopped the disease progression.

De novo membranoproliferative glomerulonephritis III in a renal transplant patient: case report and review of the literature

Idiopathic membranoproliferative glomerulonephritis (MPGN) is a rare cause of renal failure with a cumulative incidence of 0.3% of all ESRD and 4% of all primary glomerulonephritis for types I and II. Membranoproliferative glomerulonephritis type III is more uncommon and idiopathic de novo MPGN III in a renal transplant patient has not been reported. We present the case of a 57-year old white female patient with a diagnosis of lithium toxicity as cause of end stage renal disease (ESRD) who developed MPGN III in her allograft 6 years after a renal transplant. Despite treatment, she progressed to ESRD within four and a half years from the time of diagnosis.

Development of Renal Failure without Proteinuria in a Patient with Monoclonal Gammopathy of Undetermined Significance: An Unusual Presentation of AL Kappa Amyloidosis

AL amyloidosis complicating monoclonal gammopathy of undetermined significance (MGUS) has usually a predominant glomerular deposition of lambda light chain. Heavy proteinuria is one of its cardinal manifestations. A 78-year-old man with a 9-year history of IgG kappa light-chain-MGUS and normal urine protein excretion developed severe renal failure. Serum levels of kappa light chain and serum IgG had been stable while proteinuria was absent throughout the nine-year period. For the first eight years, he had stable stage III chronic kidney disease attributed to bladder outlet obstruction secondary to prostatic malignancy. In the last year, he developed progressive serum creatinine elevation, without any increase in the serum or urine levels of paraproteins or any sign of malignancy. Renal ultrasound and furosemide renogram showed no evidence of urinary obstruction. Renal biopsy revealed AL amyloidosis, with reactivity exclusive for kappa light chains, affecting predominantly the vessels and the interstitium. Glomerular involvement was minimal. Melphalan and prednisone were initiated. However, renal function continues deteriorating. Deposition of AL kappa amyloidosis developing during the course of MGUS predominantly in the wall of the renal vessels and the renal interstitium, while the involvement of the glomeruli is minimal, leads to progressive renal failure and absence of proteinuria. Renal biopsy is required to detect both the presence and the sites of deposition of renal AL kappa light chain amyloidosis.

Membranoproliferative glomerulonephritis: pathogenetic heterogeneity and proposal for a new classification

Membranoproliferative glomerulonephritis (MPGN) is a pattern of injury that results from subendothelial and mesangial deposition of Igs caused by persistent antigenemia and/or circulating immune complexes. The common causes of Ig-mediated MPGN include chronic infections, autoimmune diseases, and monoclonal gammopathy/dysproteinemias. On the other hand, MPGN also can result from subendothelial and mesangial deposition of complement owing to dysregulation of the alternative pathway (AP) of complement. Complement-mediated MPGN includes dense deposit disease and proliferative glomerulonephritis with C3 deposits. Dysregulation of the AP of complement can result from genetic mutations or development of autoantibodies to complement regulating proteins with ensuing dense deposit disease or glomerulonephritis with C3 deposits. We propose a new histologic classification of MPGN and classify MPGN into 2 major groups: Ig-mediated and complement-mediated. MPGN that is Ig-mediated should lead to work-up for infections, autoimmune diseases, and monoclonal gammopathy. On the other hand, complement-mediated MPGN should lead to work-up of the AP of complement. Initial AP screening tests should include serum membrane attack complex levels, an AP functional assay, and a hemolytic assay, followed by tests for mutations and autoantibodies to complement-regulating proteins.

Hepatitis-related renal disease

Many glomerular diseases can be caused by viral infections based on the diagnostic criteria, including clinical and laboratory data, and molecular analysis of tissue. Operative pathogenetic mechanisms include kidney tropism of the virus, immune complex formation, direct cytopathogenic effect, and multi-organ failure. Chronic infection with hepatitis virus is etiologically linked to well-defined glomerulopathies. In endemic areas, HBV is associated with both membranous nephropathy and mesangiocapillary glomerulonephritis, while HCV is known to cause cryoglobulinemia-mediated glomerulonephritis and other forms of glomerulonephritis. Renal biopsy with appropriate serological and molecular testing helps to define virus-related glomerular lesions and provides a prognostic and therapeutic guide. Antiviral agents remain the mainstay of treatment.

The 2010 nephrology quiz and questionnaire: part 2

Presentation of the Nephrology Quiz and Questionnaire (NQQ) has become an annual "tradition" at the meetings of the American Society of Nephrology. It is a very popular session judged by consistently large attendance. Members of the audience test their knowledge and judgment on a series of case-oriented questions prepared and discussed by experts. They can also compare their answers in real time, using audience response devices, to those of program directors of nephrology training programs in the United States, acquired through an Internet-based questionnaire. As in the past, the topics covered were transplantation, fluid and electrolyte disorders, end-stage renal disease and dialysis, and glomerular disorders. Two challenging cases representing each of these categories along with single best answer questions were prepared by a panel of experts (Drs. Hricik, Palmer, Bargman, and Fervenza, respectively). The "correct" and "incorrect" answers then were briefly discussed, after the audience responses and the results of the questionnaire were displayed. The 2010 version of the NQQ was exceptionally challenging, and the audience, for the first time, gained a better overall correct answer score than the program directors, but the margin was small. Last month we presented the transplantation and fluid and the electrolyte cases; in this issue we present the remaining end-stage renal disease and dialysis and the glomerular disorder cases. These articles try to recapitulate the session and reproduce its educational value for a larger audience--that of the readers of the Clinical Journal of the American Society of Nephrology. Have fun.

Proliferative glomerulonephritis secondary to dysfunction of the alternative pathway of complement

BACKGROUND AND OBJECTIVES

dense deposit disease (DDD) is the prototypical membranoproliferative glomerulonephritis (MPGN), in which fluid-phase dysregulation of the alternative pathway (AP) of complement results in the accumulation of complement debris in the glomeruli, often producing an MPGN pattern of injury in the absence of immune complexes. A recently described entity referred to as GN with C3 deposition (GN-C3) bears many similarities to DDD. The purpose of this study was to evaluate AP function in cases of GN-C3.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Five recent cases of MPGN with extensive C3 deposition were studied. Renal biopsy in one case exhibited the classic findings of DDD. Three cases showed GN-C3 in the absence of significant Ig deposition; however, the classic hallmark of DDD-dense deposits along the glomerular basement membranes and mesangium-was absent. The remaining case exhibited features of both DDD and GN-C3.

RESULTS

Evidence of AP activation was demonstrable in all cases and included increased levels of soluble membrane attack complex (all cases), positive AP functional assays (four cases), and a positive hemolytic assay (one case). Autoantibodies were found to C3 convertase (two cases) and to factor H (one case). Factor H mutation screening identified the H402 allele (all cases) and a c.C2867T p.T956M missence mutation (one case). Laser microdissection and mass spectrometry of glomeruli of GN-C3 (two cases) showed a proteomic profile very similar to DDD.

CONCLUSIONS

These studies implicate AP dysregulation in a spectrum of rare renal diseases that includes GN-C3 and DDD.

Membranoproliferative glomerulonephritis

Membranoproliferative glomerulonephritis is an uncommon kidney disorder characterized by mesangial cell proliferation and structural changes in glomerular capillary walls. It can be subdivided into idiopathic and secondary forms, which are differentially diagnosed by a review of clinical features, laboratory data, and renal histopathology. Three types-I, II, and III-have been defined by pathologic features. All three types are associated with hypocomplementemia, but they manifest somewhat different mechanisms of complement activation. Type II, also known as "dense deposit disease", is associated with the presence of C3-nephritic factor. Membranoproliferative glomerulonephritis primarily affects children and young adults, with patients presenting with nephrotic or nephritic syndrome or with asymptomatic renal disease. This type of glomerulonephritis often progresses slowly to end-stage renal disease, and it tends to recur after renal transplantation, especially type II. The efficacy of various forms of treatment remains controversial; however, long-term steroid treatment seems to be effective in children with nephrotic-range proteinuria. Improvement in renal outcomes largely relies on the evaluation of more selective agents in carefully controlled studies.

Membranoproliferative glomerulonephritis secondary to monoclonal gammopathy

BACKGROUND AND OBJECTIVES

Membranoproliferative glomerulonephritis (MPGN) is an immune complex-mediated glomerulonephritis characterized by subendothelial and mesangial deposition of immune complexes. Autoimmune diseases and chronic infections, such as hepatitis C, are commonly recognized causes of MPGN; however, monoclonal gammopathy is a less widely recognized cause of MPGN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We reviewed all renal biopsies of MPGN in Mayo Clinic patients during a 6-year period to determine the association of monoclonal gammopathy with MPGN. Results were correlated with electrophoresis studies and bone marrow biopsies to clarify the relationship between MPGN and gammopathies.

RESULTS

Of 126 patients with MPGN, 20 did not have workup for hepatitis B or C. Of the remaining 106 patients, 25 (23.5%) were positive for hepatitis B or C. Of the 81 hepatitis-negative patients, 13 were not evaluated for gammopathies. Of the remaining 68 patients, 28 (41.1%) had serum and/or urine electrophoresis studies positive for monoclonal gammopathy. Serum immunofixation electrophoresis was the most sensitive method for diagnosing monoclonal gammopathy. Renal biopsy showed a membranoproliferative pattern of injury; immunofluorescence microscopy was often instrumental in diagnosing the underlying gammopathy. On the basis of the bone marrow biopsy, monoclonal gammopathy of undetermined significance was the most common entity associated with MPGN. Other, less common causes included multiple myeloma, low-grade B cell lymphoma, and chronic lymphocytic leukemia.

CONCLUSIONS

Monoclonal gammopathy is an important and common cause of MPGN; therefore, all patients with a diagnosis of MPGN should be evaluated for an underlying monoclonal gammopathy.

Recurrent membranoproliferative glomerulonephritis after kidney transplantation

On examination of the records of 1321 patients following kidney transplant over an 11-year period, we found that 29 patients had recurrent membranoproliferative glomerulonephritis (MPGN). We excluded from this analysis patients who had MPGN type II, those with clear evidence of secondary MPGN, and those lacking post-transplant biopsies. During an average of 53 months of follow-up, we found using protocol biopsies that 12 of these patients had recurrent MPGN diagnosed 1 week to 14 months post-transplant. In 4 of the 12 patients this presented clinically, whereas the remaining had subclinical disease. The risk of recurrence was significantly increased in patients with low complement levels. Serum monoclonal proteins were found in a total of six patients; appeared to be associated with earlier, more aggressive disease; and were more common in recurrent than non-recurrent disease. The recurrence of MPGN was marginally higher in recipients of living-donor kidneys. Some patients developed characteristic lesions within 2 months post-transplant, whereas others presented with minimal, atypical histological changes that progressed to MPGN. Of 29 patients, 5 lost their allograft and 2 patients remain on chronic plasmapheresis. Our study shows the risk of MPGN recurrence and progression depends on identifiable pretransplant characteristics, has variable clinical impact, and can result in graft failure.

Prognostic factors in children with membranoproliferative glomerulonephritis type I

The clinical outcome of patients with membranoproliferative glomerulonephritis (MPGN) varies, with some patients progressing to end-stage renal disease. The aim of this retrospective study was to analyze the initial clinical signs and laboratory test results associated with an MPGN prognosis. The study cohort consisted of 47 patients with idiopathic MPGN Type I treated at the National Institute of Pediatrics, Mexico City, between 1971 and 2001. The median follow-up was 3 years. The three different outcomes of interest were death, renal failure, and nephrotic syndrome. The patients' ages ranged between 4 and 16 years. All patients had different degrees of proteinuria, hyperlipidemia, and microscopic/macroscopic hematuria, and 85.1% of them showed hypocomplementemia. Clinical outcomes varied, however, the most common was nephrotic syndrome, either alone or combined with other syndromes, which accounted for 74.5% of all cases. Fifteen patients died. Treatment with methylprednisolone improved the patient's condition, while the use of chloroquine or cyclophosphamide worsened it. Twenty-two patients had some degree of renal failure; glomerular filtration rate (GFR) levels and albumin values were negatively associated to renal failure, while treatment with methylprednisolone decreased the probability of renal failure. Nephrotic syndrome persisted in 18 patients; hemolytic complement and hemoglobin values were negatively associated with nephrotic syndrome, while macroscopic hematuria was positively associated with it. Signs that suggested a poor prognosis during diagnosis were low GFR, low albumin, low hemolytic complement, and macroscopic hematuria. Treatment with methylprednisolone seemed to improve prognosis, however, this needs to be confirmed with randomized studies.

Translational mini-review series on complement factor H: renal diseases associated with complement factor H: novel insights from humans and animals

Factor H is the major regulatory protein of the alternative pathway of complement activation. Abnormalities in factor H have been associated with renal disease, namely glomerulonephritis with C3 deposition including membranoproliferative glomerulonephritis (MPGN) and the atypical haemolytic uraemic syndrome (aHUS). Furthermore, a common factor H polymorphism has been identified as a risk factor for the development of age-related macular degeneration. These associations suggest that alternative pathway dysregulation is a common feature in the pathogenesis of these conditions. However, with respect to factor H-associated renal disease, it is now clear that distinct molecular defects in the protein underlie the pathogenesis of glomerulonephritis and HUS. In this paper we review the associations between human factor H dysfunction and renal disease and explore how observations in both spontaneous and engineered animal models of factor H dysfunction have contributed to our understanding of the pathogenesis of factor H-related renal disease.

Factor I is required for the development of membranoproliferative glomerulonephritis in factor H-deficient mice

The inflammatory kidney disease membranoproliferative glomerulonephritis type II (MPGN2) is associated with dysregulation of the alternative pathway of complement activation. MPGN2 is characterized by the presence of complement C3 along the glomerular basement membrane (GBM). Spontaneous activation of C3 through the alternative pathway is regulated by 2 plasma proteins, factor H and factor I. Deficiency of either of these regulators results in uncontrolled C3 activation, although the breakdown of activated C3 is dependent on factor I. Deficiency of factor H, but not factor I, is associated with MPGN2 in humans, pigs, and mice. To explain this discordance, mice with single or combined deficiencies of these factors were studied. MPGN2 did not develop in mice with combined factor H and I deficiency or in mice deficient in factor I alone. However, administration of a source of factor I to mice with combined factor H and factor I deficiency triggered both activated C3 fragments in plasma and GBM C3 deposition. Mouse renal transplant studies demonstrated that C3 deposited along the GBM was derived from plasma. Together, these findings provide what we believe to be the first evidence that factor I-mediated generation of activated C3 fragments in the circulation is a critical determinant for the development of MPGN2 associated with factor H deficiency.

Dense deposit disease is not a membranoproliferative glomerulonephritis

Dense deposit disease (first reported in 1962) was classified as subtype II of membranoproliferative glomerulonephritis in the early 1970s. Over the last 30 years, marked differences in etiology and pathogenesis between type I membranoproliferative glomerulonephritis and dense deposit disease have become apparent. The sporadic observation that dense deposit disease can be seen with markedly different light microscopy appearances prompted this study. The goal was to examine a large number of renal biopsies from around the world to characterize the histopathologic features of dense deposit disease. Eighty-one cases of dense deposit disease were received from centers across North America, Europe and Japan. Biopsy reports, light microscopy materials and electron photomicrographs were reviewed and histopathologic features scored. Sixty-nine cases were acceptable for review. Five patterns were seen: (1) membranoproliferative n=17; (2) mesangial proliferative n=30; (3) crescentic n=12; (4) acute proliferative and exudative n=8 and (5) unclassified n=2. The age range was 3-67 years, with 74% in the range of 3-20 years; 15% 21-30 years and 11% over 30 years. Males accounted for 54% and females 46%. All patients with either crescentic dense deposit disease or acute proliferative dense deposit disease were between the ages of 3 and 18 years. The essential diagnostic feature of dense deposit disease is not the membranoproliferative pattern but the presence of electron dense transformation of the glomerular basement membranes. Based upon this study and the extensive data developed over the past 30 years, dense deposit disease is clinically distinct from membranoproliferative glomerulonephritis and is morphologically heterogeneous with only a minority of cases having a membranoproliferative pattern. Therefore, dense deposit disease should no longer be regarded as a subtype of membranoproliferative glomerulonephritis.