Clinical characteristics and outcomes of immune-complex membranoproliferative glomerulonephritis and C3 glomerulopathy in Japanese children

BACKGROUND

Membranoproliferative glomerulonephritis (MPGN) can be divided into immune-complex MPGN (IC-MPGN) and C3 glomerulopathy (C3G), which includes dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). These conditions result from abnormalities in different complement pathways and may lead to different prognoses. However, there are limited studies describing the respective clinical courses.

METHODS

In this study, Japanese pediatric patients diagnosed with MPGN based on kidney biopsies conducted between February 2002 and December 2022 were reclassified as having IC-MPGN or C3G (DDD or C3GN). We retrospectively analyzed the clinical characteristics and outcomes of these patients.

RESULTS

Out of 25 patients with MPGN, three (12.0%) were diagnosed with DDD, 20 (80.0%) with C3GN, and two (8.0%) with IC-MPGN. There were 13 (65.0%) patients and one (33.3%) patient in remission after treatment for C3GN and DDD, respectively, and no patients with IC-MPGN achieved remission. The median follow-up period was 5.3 (2.5-8.9) years, and none of the patients in either group progressed to an estimated glomerular filtration rate < 15 ml/min/1.73 m2. Patients with C3GN presenting mild to moderate proteinuria (n = 8) received a renin-angiotensin system inhibitor (RAS-I) alone, and these patients exhibited a significant decrease in the urinary protein creatinine ratio and a notable increase in serum C3 levels at the last follow-up.

CONCLUSIONS

Most patients with MPGN were diagnosed with C3GN. The remission rate for C3GN was high, and no patients developed kidney failure during the approximately 5-year follow-up. Additionally, patients with C3GN with mild to moderate proteinuria had good outcomes with RAS-I alone, but continued vigilance is necessary to determine long-term prognosis.

Successful treatment with avacopan (CCX168) in a pediatric patient with C3 glomerulonephritis

BACKGROUND

C3 glomerulonephritis (C3GN) is a subtype of C3 glomerulopathy (C3G), characterized by dysregulation of the alternative pathway of complement and by dominant C3 by immunofluorescence on the kidney biopsy. There is no approved treatment for patients with C3G. Immunosuppressive drugs as well as biologics have been used with limited success. In recent decades, substantial advances in the understanding of the complement system have led to the development of new complement inhibitors. Avacopan (CCX168) is an orally administered small-molecule C5aR antagonist that blocks the effects of C5a, one of the most potent pro-inflammatory mediators of the complement system.

CASE REPORT

We describe a child with biopsy-proven C3GN treated with avacopan. She was enrolled in the ACCOLADE double-blind placebo-controlled Phase 2 study (NCT03301467), where during the first 26 weeks she was randomized to receive an avacopan-matching placebo orally twice daily, while in the following 26 weeks, the study was open-label and she received avacopan. After a wash-out period, she was restarted on avacopan through an expanded access program.

CONCLUSIONS

In this case, use of avacopan in a pediatric patient with C3GN was safe and well tolerated. On avacopan, the patient was able to discontinue mycophenolate mofetil (MMF) while maintaining remission.

IgA nephropathy to proliferative glomerulonephritis with monoclonal IgAκ deposits: a pattern switch

We report the case of a 31-year-old male who presented with repeated episodes of nephritic-nephrotic syndrome in concomitance with infection. IgA was diagnosed and was initially responsive to treatment with immunosuppressors but further disease flare did not respond to treatment. Based on three consecutive renal biopsies over 8 years, a pattern switch from endocapillary proliferative IgA nephropathy to membranous proliferative glomerulonephritis with monoclonal IgAκ deposits was observed. Bortezomib-dexamethasone combination therapy finally led to a favorable renal response. This case provides new insights into the pathophysiological mechanisms of proliferative glomerulonephritis with monoclonal immunoglobin deposits (PGNMID), highlighting the importance of repeat renal biopsies and routine evaluation of monoclonal immunoglobin deposits in proliferative glomerulonephritis with refractory nephrotic syndrome.

Demographics and treatment of patients with primary membranoproliferative glomerulonephritis in Japan using a national registry of clinical personal records

BACKGROUND

Membranoproliferative glomerulonephritis (MPGN) is a rare glomerular injury that causes nephrotic syndrome and end-stage kidney disease. The nationwide demographics and treatment of Japanese patients with primary MPGN have not yet been reported.

METHODS

We collected clinical personal records of patients with primary MPGN between 2015 and 2018 from the national registry organized by the Japanese Ministry of Health, Labour, and Welfare and investigated the characteristics of primary MPGN throughout Japan.

RESULTS

Of 258 patients with primary MPGN, 199 and 59 showed nephrotic and non-nephrotic syndrome, respectively. The median age at onset was higher in patients with nephrotic syndrome than in those with non-nephrotic syndrome (45 [24-63] vs. 35 [14-53] years, respectively; P = 0.010). The use of oral prednisolone was significantly higher in patients with nephrotic syndrome than in those with non-nephrotic syndrome (73.9% vs. 59.3%, respectively; P = 0.032). When patients were divided into three age groups: adolescent and young adult group (≤ 39 years; n = 80), middle adult group (40-64 years; n = 111), and older adult group (≥ 65 years; n = 67), the use of oral prednisolone, cyclosporine, and mizoribine was significantly higher in the adolescent and young adult group than in the middle adult group. The mean dosage of oral prednisolone and mizoribine showed no differences among the three age groups.

CONCLUSION

The national registry of clinical personal records of primary MPGN could provide an informative insight into the characteristics, clinical features, and treatment approaches for patients with primary MPGN in Japan.

Gaucher disease in a patient with membranoproliferative glomerulonephritis: case report

BACKGROUND

Gaucher disease (GD) is a rare autosomal recessive inherited, lysosomal storage disoder that involves liver, spleen, lung, bone, bone marrow even central nervous. However, GD associated membranoproliferative glomerulonephritis (MPGN) is seldom reported.

CASE PRESENTATION

Here we described a case of 35-year-old man suffering from GD with hepatosplenomegaly, ascites, bone destruction, myelofibrosis and MPGN. Renal biopsy revealed MPGN and Gaucher cells presented in the glomeruli capillaries. β-glucosidase activity was 1.95nmol/1 h/mg and gene detection demonstrated that one homozygous pathogenic variant Leu483Pro in GBA. He received the treatment of oral prednisone and mycophenolate mofetil and his ascites and renal outcomes had been significantly improved.

CONCLUSIONS

Therapy of prednisone and mycophenolate mofetil may be an optional choice for patients with Gaucher disease who have no opportunity to use enzyme treatment.

Clinical features and outcomes of patients with diacylglycerol kinase epsilon nephropathy: a nationwide experience

BACKGROUND

Thrombotic microangiopathy (TMA) is usually caused due to dysregulation of the alternative complement pathway. Rarely, thrombotic microangiopathy is caused by non-complement mediated mutations in diacylglycerol kinase epsilon (DGKE); information about therapy and outcome of these patients is limited.

METHODS

Medical records of patients, younger than 18 years, diagnosed with TMA and variants in DGKE were reviewed to include 12 patients from seven centers. Genetic studies included targeted exome sequencing and multiplex-ligation dependent probe amplification of CFH-CFHR5.

RESULTS

Patients presented at a median age of 11 (7.5, 12.3) months; all were younger than 2 years. All patients had an infectious prodrome; enteroinvasive, enteropathogenic, and enterotoxigenic Escherichia coli were detected in two patients with diarrhea. Chief features included those of microangiopathic hemolysis (n = 11), microscopic hematuria (n = 10), nephrotic range proteinuria (n = 10), hypoalbuminemia (n = 6), elevated total cholesterol (n = 6), and hypocomplementemia (n = 4). Histopathology showed thrombotic microangiopathy (n = 4), overlapping with membranoproliferative pattern of injury (n = 1). At median 3.3 years of follow-up, significant hypertension and/or proteinuria (40%), relapses (66.7%), and death or progression to CKD (60%) were common. Genetic sequencing showed 13 homozygous and compound heterozygous variants (7 pathogenic, 3 likely pathogenic) located throughout DGKE; 11 variants were novel.

CONCLUSIONS

This case series highlights the need to suspect DGKE nephropathy in young patients with TMA, especially those with severe proteinuria. Medium-term outcomes are unsatisfactory with risk of relapses, progressive kidney failure, and death. A higher resolution version of the Graphical abstract is available as Supplementary information.

Nephrotic-range proteinuria and membranoproliferative glomerulonephritis-like pattern caused by interferon-β1b in a patient with multiple sclerosis

Interferon-beta (IFN-β) subtypes are widely used as immunomodulatory agents for relapsing-remitting multiple sclerosis (MS). Although generally well tolerated, a growing number of reports have recently shown association of long-term IFN-β therapy with several types of glomerulonephritis. Here, we present the case of a 42-year-old woman with MS who developed nephrotic-range proteinuria after taking IFN-β1b for nine years. Initially, due to the presence of histological features consistent with immunoglobulin A (IgA) nephropathy (granular IgA deposits in mesangial lesions), a tonsillectomy plus steroid pulse therapy was performed. However, proteinuria did not significantly decrease after these treatments. Therefore, a second renal biopsy was performed after three years, revealing a membranoproliferative glomerulonephritis-like pattern without immune complex. Further immunofluorescence analysis showed attenuated IgA staining. Consequently, IFN-β1b was replaced with dimethyl fumarate, resulting in complete remission, with proteinuria decreasing to the level of 0.2 g/day. Although it is a rare adverse effect, physicians should pay careful attention to the symptoms and findings of nephritis during the follow-up of patients under treatment with this agent.

Infection related membranoproliferative glomerulonephritis secondary to anaplasmosis: A case report

BACKGROUND

Anaplasmosis is a tick-borne disease with a range of clinical manifestations, from a flu-like illness with fever and myalgias to a severe systemic disease with multisystem organ failure. Although renal involvement is not a common presentation, there have been few cases reporting acute kidney injury from Anaplasmosis.

CASE SUMMARY

We present a 55-year-old female with anaplasmosis who developed acute kidney injury due to membranoproliferative glomerulonephritis (MPGN). The patient originally presented with cough and shortness of breath. She was admitted to the hospital with a diagnosis of community acquired pneumonia and received antibiotics. During the hospital course she developed severe acute renal failure. Initial serological work up didn’t provide any conclusive diagnosis. Hence, she underwent kidney biopsy which showed MPGN pattern suggesting autoimmune, multiple myeloma or infectious etiology. Extensive work up was undertaken which was negative for autoimmune diseases, vasculitis panel, paraproteinemias but tested positive for IgG anaplasma with high titers indicating Anaplasmosis.

CONCLUSION

Our case shows a unique presentation of severe acute renal failure from MPGN from tick borne illness. MPGN is usually seen with autoimmune diseases, hepatitis C virus infections, paraproteinemias. Hence, we suggest that tick borne illness should also be considered when evaluating acute renal failure cases in tick borne prevalent regions.

Siltuximab Monotherapy in Tafro Syndrome: A Case Report and Review of the Literature

TAFRO syndrome is characterized by the presence of thrombocytopenia, anasarca, fever, reticular myelofibrosis, organomegaly, and is frequently associated with kidney damage in the form of membranoproliferative glomerulonephritis (MPGN) or thrombotic microangiopathy (TMA). Treatment is based on corticosteroids. A 59-year-old man who suffered from heart disease, pancytopenia and hepatosplenomegaly of unknown etiology developed nephrotic syndrome and progressive renal insufficiency, with a kidney biopsy suggestive of MPGN with a "full-house" immunofluorescence pattern. Positron emission tomography (PET) revealed multiple lymphadenopathies which histologically were compatible with multicentric Castleman's disease. The patient was diagnosed with TAFRO syndrome and treatment with siltuximab was started, with evident improvement at 3 months. TAFRO syndrome is a rare entity which may present with severe kidney involvement and histological findings of MPGN or TMA, with or without immune complex deposits. Our case suggests that a corticosteroid-free regimen with siltuximab could be an attractive therapeutic option.

An Unusual Case of Seronegative Cryoglobulinemic Glomerulonephritis with Dominant Organized IgA Deposits Associated with Staphylococcal Infection: Casual or Causal Relationship?

Introduction

Cryoglobulinemia refers to the presence of cryoglobulins (CGs) in the serum, encompassing a group of diseases caused by the type of circulating GC. Cryoglobulinemic glomerulonephritis (CryoGN) is the principal manifestation of renal involvement. The diagnosis may be challenging because the hallmark of cryoglobulinemia is the detection of CG in the serum. However, cases of CryoGN without serological evidence of CGs are not uncommon in clinical practice, often diagnosed by anatomopathological findings in the renal biopsy.

Case Presentation

We report the case of an 86-year-old male who developed renal impairment, nephritic syndrome, and nephrotic-range proteinuria, without serological evidence of CGs, associated with staphylococcal bacteremia without apparent focus. Renal biopsy and pathological examination showed a membranoproliferative glomerulonephritis pattern with CD61-negative pseudothrombi. Immunofluorescence microscopy showed atypical IgA-dominant deposits. Electron microscopy revealed amorphous subendothelial and mesangial deposits and organized electrodense deposits within capillary loops (pseudothrombi) with microtubular substructure measuring 20-40 nm in thickness. These findings were consistent with seronegative CryoGN and microtubular organized atypical IgA-dominant deposits.

Discussion

In this report, we discuss the clinical, analytical, and histopathological findings of a rare case of CryoGN without serological evidence of CGs. Regarding the etiology that triggered the glomerular disease in our patient, we conducted an exhaustive study in order to determine the underlying cause of CryoGN. At the time of biopsy, the patient had an active staphylococcal bacteremia. There are reports that postulate that staphylococcal antigens drive activation of immune system and in consequence, could cause this rare form of IgA-dominant glomerulonephritis with cryoglobulinemic features. After ruling out other causes of cryoglobulinemia, we discuss a plausible causal relationship of the staphylococcal infection in the pathogenesis of CryoGN in our patient.

Poor outcomes of proliferative glomerulonephritis with monoclonal IgG deposits in renal allografts: a retrospective multicenter study

BACKGROUND

Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) in renal allografts is a rare, renal-limited disease. No study has reported the long-term outcomes and prognostic features of PGNMID in renal allografts in the Chinese population.

METHODS

We retrospectively included transplant patients diagnosed with PGNMID who underwent renal allograft biopsy at three transplant centers from April 2012 to July 2020. We observed the clinicopathologic features, explored the long-term graft survival, and investigated the characteristics associated with the prognosis.

RESULTS

A total of 13 transplant patients with PGNMID were included, out of 3821 biopsies. The mean follow-up time was 55 months since kidney transplantation (KTx). At diagnosis, all patients presented with proteinuria (100%) and most of them with hematuria (92%). IgG3κ (69%) was the main immunofluorescence (IF) subtype. The median graft survival of the total cohort was 17 months from diagnosis and 49 months from kidney transplantation. During follow-up, 9 patients needed dialysis and 2 out of 9 patients who progressed to dialysis died of infection. Primary membranoproliferative glomerulonephritis (MPGN) (P = 0.014) and MPGN pattern at diagnostic biopsy (P < 0.001) were associated with a higher risk of graft loss.

CONCLUSIONS

The long-term outcome of allograft PGNMID was relatively poor in the Chinese population. Primary MPGN and MPGN pattern in renal allograft were associated with  poor outcomes.

Diffuse alveolar hemorrhage: Rare presentation of type 1 cryoglobulinemia in marginal B-cell lymphoma

Cryoglobulinemia (CG) is defined as the presence of abnormal immunoglobulins (Igs)that precipitate at low temperatures and dissolve upon warming. The manifestations in type I cryoglobulinemia are often related to intravascular obstruction which include skin, joint, renal and neurological involvement. We report a rare case of type 1 CG that presented with diffuse alveolar hemorrhage. Following extensive workup, the patient was found to have membranoproliferative glomerulonephritis secondary to type 1 CG in the setting of marginal B cell lymphoma. He was started on an aggressive regimen targeting underlying lymphoma. Key to managing this condition was multidisciplinary approach towards the diagnosis and management of this otherwise challenging case.

A rare case of proliferative glomerulonephritis with monoclonal IgG2 kappa deposit: a case report

BACKGROUND

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) is a rare monoclonal gammopathy of renal significance with dense deposits of monoclonal immunoglobulin.

CASE PRESENTATION

We report a 78-year-old Japanese male patient with mild proteinuria and lower extremity edema. Monoclonal immunoglobulin could not be identified in his serum or urine. Although his bone marrow biopsy was negative, renal biopsy found features of membranoproliferative glomerulonephritis (MPGN) with deposition of monoclonal IgG2 kappa. Electron microscopy examination revealed non-organized electron-dense deposits in the subepithelial, and subendothelial mesangial regions. Steroid monotherapy was performed after diagnosis of PGNMID but complete remission was not achieved.

CONCLUSION

PGNMID with IgG3 kappa deposits is the most common in cases with the histological feature of MPGN. There are few cases of PGNMID with IgG2 kappa deposits exhibiting MPGN. This report describes a very rare case of PGNMID with the histological feature of MPGN.

KM55 in the Evaluation of IgA-Containing Glomerular Diseases

Introduction

Mucosal-derived galactose-deficient IgA is central to the pathogenesis of primary IgA nephropathy (IgAN). Recent reports suggest similar pathogenesis in Henoch-Schonlein purpura (HSP) and secondary IgAN. Its role in other IgA-containing glomerular diseases is still under investigation. It can be detected in glomeruli with the recently described antibody KM55. We aimed to evaluate the role of KM55 by immunostaining a wide spectrum of IgA-containing glomerular diseases.

Methods

After standardization and colocalization in a case of IgAN, a spectrum of 60 cases including IgAN, HSP, chronic liver disease (CLD)-related IgAN, other secondary IgAN, IgA-dominant/codominant membranoproliferative glomerulonephritis (MPGN), and lupus nephritis were subjected to immunofluorescence with KM55. KM55 was used to resolve diagnostic dilemma in cases of IgA deposition with confounding histology.

Results

The group of primary IgAN (17 cases), HSP (4 cases), and secondary IgAN (19 cases) including CLD showed 2-3+ granular staining with KM55, suggesting mucosal-derived IgA. In contrast, cases of IgA-dominant/codominant MPGN (8 cases) and lupus nephritis (12 cases) were negative for KM55, suggesting systemic derivation of IgA. In cases of IgA deposition with confounding histology such as membranoproliferative or diffuse endocapillary proliferative pattern, KM55 helped to resolve the diagnosis.

Discussion/Conclusion

This cross-sectional study concludes that KM55 is useful in the evaluation of IgA-containing glomerular diseases from a pathogenetic perspective and is a practical tool in resolving differential diagnosis in cases with overlapping histopathological features.

Characteristics and outcomes of glomerulonephritis with membranoproliferative pattern in children

BACKGROUND

Membranoproliferative glomerulonephritis (MPGN) is a rare histopathologic pattern of glomerular injury with limited studies in pediatric patients. Characteristics and outcomes of children with MPGN have also remained to be further explored.

METHODS

We retrospectively reviewed the clinicopathological features, genetic findings, treatments and outcomes in 17 pediatric patients pathologically diagnosed with MPGN from 2007 to 2020 in the Children's National Medical Center in China.

RESULTS

Median age at disease onset was 9.9 years (IQR, 5.6-11.9 years). Most of the patients (12/17) had nephrotic range of proteinuria, and nephritic-nephrotic syndrome was the most common clinical presentation (35.2%). Secondary causes were identified in eight patients including hepatitis B virus (HBV) infection (n=4), methylmalonic acidemia (MMA, n=2), rheumatoid arthritis (RA, n=1) and Aymé-Gripp Syndrome (n=1). The nine patients with primary MPGN were further identified as immune-complex mediated MPGN (n=8), and unclassifiable MPGN (U-MGPN, n=1). Genetic analyses identified pathogenic variants of MMACHC gene in two cases of MMA and established the diagnosis for Aymé-Gripp syndrome in one case with a de novo variant of MAF gene. Comparing study between the complete or partial remission group (n=8) and non-response group (n=9) showed a significant difference in the timing of renal biopsy (P<0.05). Normal renal function was preserved in ten patients at the last follow-up. Two patients developed into end-stage renal disease (ESRD).

CONCLUSIONS

Children with MPGN pattern present heterogenous clinical features. Genetic detection helps to explore underlying causes of MPGN. Early identification of the primary or secondary causes of MPGN in children is vital.

Recurrence of Cryoglobulinemia Secondary to Hepatitis C in a Patient with HCV RNA (-) Negative in the Serum

Hepatitis C virus infection is associated with many extrahepatic manifestations such as mixed cryoglobulinemia (MC). Renal manifestation of HCV infection might present as cryo-positive membranoproliferative glomerulonephritis (MPGN). First-line therapy includes antiviral treatment as the underlying infection leads to formation of immune complexes. After introducing direct-acting antiviral agents (DAAs) cure rates of HCV infection increased. Sustained virologic response (SVR) is defined as the absence of HCV RNA in serum by a sensitive test performed 12 or 24 weeks after the end of antiviral treatment. Although HCV RNA is undetectable in the serum, it may be present in hepatocytes and peripheral blood mononuclear cells (occult HCV infection). However, the impact of DAA treatment on occult HCV infection is not clear. We report a case of recurrence of MC with MPGN and development of lymphoproliferative disorder 2 years after achieving SVR.

Cryofibrinogen-associated glomerulonephritis accompanied by advanced gastric cancer

We had a 72-year-old man with advanced gastric cancer, poorly differentiated adenocarcinoma, receiving chemotherapy with S-1 (tegafur, gimeracil, and oteracil potassium) plus oxaliplatin. Ascites developed despite remission of gastric cancer and metastasis. Given no malignant cells in ascites, leg edema, renal impairment, hypoalbuminemia, and massive proteinuria, we diagnosed as nephrotic syndrome with microscopic hematuria. Renal biopsy showed membranoproliferative glomerulonephritis with no deposition of immunoglobulins and complements. Of note, electronic microscopy found organized deposits with microtubular structures in the glomerular capillary lumens and subendothelial spaces. The liquid chromatography-tandem mass spectrometry method detected fibrinogen alpha chain, beta chain, gamma chain, and fibronectin, and we eventually diagnosed cryofibrinogen-associated glomerulonephritis. Cryofibrinogen was not detected in plasma. He was expired at 5 months following renal biopsy due to the progression of refractory nephrotic syndrome. In addition to the detailed assessment of specifically organized deposits, the analysis using liquid chromatography-tandem mass spectrometry method is useful to diagnose cryofibrinogen-associated glomerulonephritis. We should consider cryofibrinogen-associated glomerulonephritis as a differential diagnosis when the patients with malignancy showed abnormal urinalysis and renal impairment, though it is a rare disease.

Primary membranoproliferative glomerulonephritis in Sfax, Tunisia: epidemiologic profile and prognostic factors

Introduction

membranoproliferative glomerulo nephritis (MPGN) is a rare kidney disease with a poor prognosis as 50% of patients attend the end stage renal failure after 10 years of follow up. Several factors have been described associated with poor renal prognosis. The aim of our study is to determine the epidemiologic profile and to identify prognostic factors of MPGN.

Methods

our study is retrospective over a period of 16 years (January 1996 - December 2011) including all cases of primary MPGN aged more than 15 years, collected at the nephrology department of Hedi Chaker University Hospital, Sfax, Tunisia.

Results

we collected 118 cases of primary MPGN, with mean age of 45 (SD 19) years. The incidence of MPGN has decreased from 10 cases/year between 1996 and 1999 to 5 cases/year between 2008 and 2011. Seventy-nine percent of patients (n=93) had renal failure at the moment of diagnosis (e-GFR less than 60 ml/min/1.73m²;). After a mean follow-up of 51.9 (SD 44) months, progression to end stage renal failure was observed in 43.5% of followed cases (n=20). On univariate analysis, factors associated with death or progression to end stage renal failure were initial renal failure and sclerotic glomeruli (respectively p at 0.040 and 0.032). Multivariate analysis indicated that initial renal failure was significantly correlated with death or progression to end stage renal failure (HR: 0.14, 95% CI (0.033-0.593), p=0.008).

Conclusion

there has been a decline in the number of cases of MPGN diagnosed in our hospital. The presence of renal failure at diagnosis was associated with death or progression to end stage renal failure.

Recurrence of Proliferative Glomerulonephritis with Monoclonal Immunoglobulin G Deposits with a Striated Ultrastructure

A 64-year-old man with nephrotic syndrome was admitted to another hospital where his renal biopsy revealed membranoproliferative glomerulonephritis (MPGN) with monoclonal immunoglobulin (Ig) G, subclass 1, κ light chain (IgG1κ) deposition on immunofluorescence (IF). Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) was suspected due to monoclonal IgG1κ deposits and the absence of hematological abnormalities. However, the typical PGNMID phenotype was not observed by electron microscopy. Instead, an organized and striated muscle-like structure was observed in the subendothelial space. Since a 2-year treatment with immunosuppressants did not improve his proteinuria, a second biopsy was performed at our hospital. It showed an MPGN-like phenotype; however, monoclonal Ig deposits on IF were no longer observed. One year after the second biopsy, he developed ESRD. Thus, he underwent living kidney transplantation from his wife. Allograft biopsy was performed as proteinuria was observed 3 months after transplantation, which again showed an MPGN-like phenotype with monoclonal IgG1κ deposits. The observed electron-dense deposits were similar to those in the native biopsies. Accordingly, the patient was diagnosed with recurrent MPGN. Adding methylprednisolone pulse therapy to conventional immunosuppressants did not improve the patient's renal function or proteinuria. He died of Legionella pneumonia 8 months after transplantation. Considering the patient's histological findings of MPGN with monoclonal IgG1κ deposits and early recurrence of glomerulonephritis after transplantation, he was diagnosed with PGNMID with novel electron-dense deposits.

[Renal involvement in Sjögren's syndrome]

Primary Sjögren syndrome is an autoimmune disorder characterized by lymphoplasmacytic infiltration of the exocrine (salivary and lachrymal) glands resulting in sicca symptoms (dryness). Systemic complications can occur in primary Sjögren syndrome, but renal involvement is rare, affecting<10% patients. The most frequent form of nephropathy in primary Sjögren syndrome is tubulointerstitial nephritis, where infiltration of the kidney by plasma cells is a key feature and shows similarity to the lymphoplasmacytic infiltration of the salivary glands. Electrolyte disturbances may occur in primary Sjögren syndrome, such as renal distal tubular acidosis, diabetes insipidus, Gitelman syndrome, or Fanconi syndrome. Glomerular involvement is less frequently detected in patients with primary Sjögren syndrome, but can take the form of membranoproliferative glomerulonephritis secondary to cryoglobulinaemia. The renal prognosis in patients with primary Sjögren syndrome and TIN or glomerular disease is usually good, but the risk of chronic kidney disease remains significant for some patients. Appropriate screening must be performed at least once a year in patients with systemic primary Sjögren syndrome in order to facilitate the early detection of renal complications. In this Review, we discuss the epidemiology, pathophysiology, differential diagnosis, and treatment of renal disease in primary Sjögren syndrome.

Immune-complex glomerulonephritis with a membranoproliferative pattern in Frasier syndrome: a case report and review of the literature

Background

Mutations in the Wilms tumor 1 gene cause a spectrum of podocytopathy ranging from diffuse mesangial sclerosis to focal segmental glomerulosclerosis. In a considerable fraction of patients with Wilms tumor 1 mutations, the distinctive histology of immune-complex-type glomerulonephritis has been reported. However, the clinical relevance and etiologic mechanisms remain unknown.

Case presentation

A 5-year-old child presented with steroid-resistant nephrotic range proteinuria. Initial renal biopsy revealed predominant diffuse mesangial proliferation with a double-contour and coexisting milder changes of focal segmental glomerulosclerosis. Immunofluorescence and electron microscopy revealed a full-house-pattern deposition of immune complexes in the subendothelial and paramesangial areas. Serial biopsies at 6 and 8 years of age revealed that more remarkable changes of focal segmental glomerulosclerosis had developed on top of the initial proliferative glomerulonephritis. Identification of a de novo Wilms tumor 1 splice donor-site mutation in intron 9 (NM_024426.6:c.1447 + 4C > T) and 46,XY-gonadal dysgenesis led to the diagnosis of Frasier syndrome.

Conclusions

Our findings, together with those of others, point to the importance of heterogeneity in clinicopathological phenotypes caused by Wilms tumor 1 mutations and suggest that immune-complex-mediated membranoproliferative glomerulopathy should be considered as a histological variant.

The impact of reclassification of C3 predominant glomerulopathies on diagnostic accuracy, outcome and prognosis in patients with C3 glomerulonephritis

Background

C3 glomerulonephritis is a recently described entity with heterogeneous histopathological features. This study was conducted to assess the effect of reclassification of C3 glomerulopathies on renal outcomes, mortality, and response to therapy.

Methods

We undertook a retrospective analysis of 857 renal biopsies collected at The Canberra Hospital. Samples with predominant C3 staining were reviewed by a renal histopathologist. Of 31 biopsies with predominant C3 staining, 10 fulfilled histological criteria for C3 glomerulonephritis, while the remaining 21 cases were used as C3 Controls.

Results

Aside from a higher incidence of C3 glomerulonephritis in Torres Strait islanders (40% vs 5% C3 Controls, p = 0.04), presentation demographics were similar between the two groups. Median creatinine at diagnosis was higher in patients with C3 glomerulonephritis (253 umol/L IQR 103–333 vs 127 umol/L C3 Controls, IQR 105–182, p = 0.01).

Prior to reclassification, a majority of C3 glomerulonephritis cases were diagnosed as membranoproliferative glomerulonephritis (60% vs 5% (C3 Controls) p < 0.01). Electron microscopy demonstrated all C3 glomerulonephritis patients had C3 deposition (100% vs 38% p = 0.02), these deposits were amorphous in nature (50% vs 5% respectively p = 0.007).

C3 glomerulonephritis patients had shorter median follow-up (405 days IQR 203–1197 vs 1822 days respectively, IQR 1243–3948, p = 0.02). Mortality was higher in C3 glomerulonephritis patients (30% vs 14% in C3 Controls (log rank p = 0.02)).

Conclusion

We have devised a diagnostic and treatment algorithm based on the results of literature review and our current study. Further prospective assessment is required to review diagnostic and treatment outcomes for this disease in Australian centres.

Clinicopathological characteristics and outcome of patients with fibrillary glomerulonephritis: DNAJB9 is a valuable histologic marker

BACKGROUND

Fibrillary glomerulonephritis (FGN) is a rare glomerular disease. DNAJB9 as a new reliable diagnostic marker for the diagnosis of FGN was discovered recently. To investigate the clinicopathological features and prognosis of DNAJB9-positive FGN, we report on a case series in a single center in China.

METHODS

DNAJB9 immunohistochemistry was performed on renal biopsy samples from patients with FGN (n = 7), and non-FGN glomerular diseases (n = 27) were used as controls. The patients with DNAJB9-positive FGN were retrospectively analyzed.

RESULTS

Strong DNAJB9 staining of glomerular extracellular deposits was observed in 6 cases of originally diagnosed FGN. One man and 5 women with a median age of 26 years were studied. The patients presented with renal insufficiency in 1 case, proteinuria in 6 cases, nephrotic syndrome in 3 cases, and microscopic hematuria in 2 cases. The histologic pattern was mesangial proliferative glomerulonephritis in 1 case and membranoproliferative glomerulonephritis in 5 cases. The glomerular deposits stained for polytypic IgG and both kappa and lambda in 3 cases, polytypic IgG without kappa or lambda in 1, monotypic IgG1-kappa in 1 and IgG1-lambda in 1. Extraglomerular deposits were identified in all cases. Congo red positivity was observed in 3 cases. All of the patients received renin-angiotensin-aldosterone system blockade and 5 of them received glucocorticoid and/or immunosuppression. At a median time of 36.2 months after biopsy, 2 cases had partial remission, 3 cases displayed no remission, and 1 case progressed to end-stage renal disease.

CONCLUSIONS

Extraglomerular deposits in the FGN were common. Monotypic FGN was found in young patients with a favorable renal outcome.

C3 Glomerulopathy: Pathogenesis and Treatment

C3 glomerulopathy (C3G) is a rare set of kidney diseases with 2 patterns: C3 glomerulonephritis (C3GN) and dense deposit disease. Pathogenesis of both diseases is due to complement dysregulation in the alternative pathway. Acquired or genetic alterations of the regulatory proteins of the complement pathway result in C3G. Although the disease is characterized by low C3 levels in serum and C3-dominant staining by immunofluorescence on biopsy, other disease entities such as infection-related glomerulonephritis and masked monoclonal deposits can present similarly. Both the C3GN and dense deposit disease variants of C3G are progressive and recur in transplanted kidneys. Although no direct treatment is available, complement blockers are either available or in the clinical trial phase. This review will survey the pathogenesis of C3GN and current treatment options.

Membranoproliferative glomerulonephritis related to a streptococcal infection in a girl with IgA deficiency: a case report

Background

IgA deficiency associated with glomerulonephritis is rare. In particular, there is no prior report regarding the association between IgA deficiency and membranoproliferative glomerulonephritis (MPGN) in children. Herein, we describe the case of a 5-year-old girl with selective IgA deficiency and MPGN.

Case presentation

The patient presented with persisting urinary abnormality and hypocomplementemia following a group A treptococcal infection. Renal biopsy revealed the presence of diffuse mesangial hypercellularity, endocapillary proliferation, and focal thickening of the walls of the glomerular capillaries using light microscopy, with IgG and moderate C3 deposits observed using immunofluorescence. Electron microscopy images revealed nodular deposits in the subendothelial areas, with hump-shaped subepithelial deposits. The pathological diagnosis was confirmed as MPGN. Treatment using oral prednisolone (PSL), mizoribine (MZR), and angiotensin-converting enzyme inhibitors reduced the proteinuria. The PSL dose was gradually tapered, with the low dose of PSL and MZR continued for 4 years. Histological findings were improved on repeated renal biopsy, and PSL and MZR administration was discontinued.

Conclusions

We report a rare case of MPGN related to a streptococcal infection in a child. The clinical presentation included selective IgAD, with several pathological findings and a clinical course typical of glomerulopathy. The patient was successfully treated using multidrug therapy.

Morphofunctional Effects of C5 Convertase Blockade in Immune Complex-Mediated Membranoproliferative Glomerulonephritis: Report of Two Cases with Evidence of Terminal Complement Activation

A membranoproliferative pattern of glomerular injury is frequently observed in patients with complement-mediated disorders, such as C3 glomerulopathies (C3G) and primary immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN). The outcomes of C3G and -IC-MPGN are poor, independently of immunosuppressive therapy. However, two 48-week treatment periods with the anti-C5 monoclonal antibody eculizumab, divided by a -12-week washout period, achieved remission of proteinuria and stabilization/improvement of the glomerular filtration rate (GFR), measured through iohexol plasma clearance, in 3 of 10 patients with biopsy-proven MPGN, nephrotic syndrome and terminal complement complex sC5b-9 plasma levels >1,000 mg/mL, at inclusion. Baseline and end-of-study kidney biopsies were available for 2 patients with IC-MPGN, and their baseline characteristics were similar. However, in 1 patient proteinuria and GFR did not improve during the study, whereas in the other proteinuria decreased from 4.84 to 2.12 g/24-h and GFR increased from 91.5 to 142.7 mL/min/1.73 m2. Glomerular inflammation improved and median (interquartile range) glomerular staining for C5b-9 decreased in both cases: from 23.6 to 18.2% (p = 0.021) in the patient who achieved remission and from 15.8 to 10.7% (p = 0.019) in the patient with persistent proteinuria. Chronic glomerular lesions progressed and C3 glomerular staining and electron-dense deposits did not change appreciably in either case. However, in the patient who achieved remission, ultrastructural evaluation revealed features of glomerular microangiopathy at inclusion, which fully recovered posttreatment. Podocyte foot process effacement was observed in both patients at inclusion, but recovered only in the patient with microangiopathy. Thus, in 2 patients with -IC-MPGN, chronic glomerular changes progressed despite eculizumab-induced amelioration of glomerular inflammation and inhibition of sC5b-9 deposition, and independently of treatment effects on proteinuria and podocytes. The finding that the regression of microangiopathic changes was associated with improved clinical outcomes suggests that C5 blockade might have a therapeutic role in patients with IC-MPGN displaying microangiopathic endothelial injury.

Characteristic electron-microscopic features of cryofibrinogen-associated glomerulonephritis: a case report

Background

Cryofibrinogenemia is a rare disorder that mainly affects the skin and occasionally the kidney. However, there are few published reports of cryofibrinogenemia-associated renal pathology. We therefore report a patient with cryofibrinogen-associated glomerulonephritis. Samples from this patient were examined by electron microscopy, laser microdissection, and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Case presentation

A 78-year-old Japanese man presented with declining renal function, proteinuria, and gross hematuria. Kidney biopsy showed a membranoproliferative pattern with crescent formation and dominant C3c deposition in which subendothelial deposits with uniquely organized electron-microscopic features were observed. Additional ultrastructural analysis of cryoprecipitates extracted from plasma revealed similar structures of the glomerular subendothelial deposits. LC-MS/MS identified an increase in fibrinogen α, β, and γ chains, fibronectin, filamin-A, and C3. The glomerular lesions were diagnosed as cryofibrinogen-associated glomerulonephritis on the basis of these findings.

Conclusions

Although there are few reports of cryofibrinogen-associated glomerulonephritis, we believe that accurate diagnosis can be achieved by performing LC-MS/MS and ultrastructural analysis.

Long-term outcomes of patients with end-stage kidney disease due to membranoproliferative glomerulonephritis: an ANZDATA registry study

Background

Membranoproliferative glomerulonephritis (MPGN) is an uncommon cause of end stage kidney disease (ESKD) and the clinical outcomes of patients with MPGN who commence kidney replacement therapy have not been comprehensively studied.

Methods

All adult patients with ESKD due to glomerulonephritis commencing kidney replacement therapy in Australia and New Zealand from January 1, 1996 to December 31, 2016 were reviewed. Patients with ESKD due to MPGN were compared to patients with other forms of glomerulonephritis. Patient survival on dialysis and following kidney transplantation, kidney recovery on dialysis, time to transplantation, allograft survival, death-censored allograft survival and disease recurrence post-transplant were compared between the two groups using Kaplan Meier survival curves and Cox proportional hazards regression.

Results

Of 56,481 patients included, 456 (0.8%) had MPGN and 12,660 (22.4%) had another form of glomerulonephritis. Five-year patient survival on dialysis and following kidney transplantation were similar between patients with ESKD from MPGN and other forms of glomerulonephritis (Dialysis: 59% vs. 62% p = 0.61; Transplant: 93% vs. 93%, p = 0.49). Compared to patients with other forms of glomerulonephritis, patients with MPGN had significantly poorer 5-year allograft survival (70% vs. 81% respectively, p = 0.02) and death censored allograft survival (74% vs. 87%, respectively; p < 0.01). The risk of disease recurrence was significantly higher in patients with MPGN compared to patients with other glomerulonephritidites (18% vs. 5%; p < 0.01). In patients with MPGN who had allograft loss, patients with MPGN recurrence had a significantly shorter time to allograft loss compared to patients with MPGN who had allograft loss due to any other cause (median time to allograft loss 3.2 years vs. 4.4 years, p < 0.01).

Conclusions

Compared with other forms of glomerulonephritis, patients with MPGN experienced comparable rates of survival on dialysis and following kidney transplantation, but significantly higher rates of allograft loss due to disease recurrence.

Complement dysregulation in glomerulonephritis

Glomerulonephritis (GN) refers to a group of renal diseases affecting the glomeruli due to the damage mediated by immunological mechanisms. A large proportion of the disease manifestations are caused by disturbances in the complement system. They can be due to genetic errors, autoimmunity, microbes or abnormal immunoglobulins, like modified IgA or paraproteins. The common denominator in most of the problems is an overactive or misdirected alternative pathway complement activation. An assessment of kidney function, amount of proteinuria and hematuria are crucial elements to evaluate, when glomerulonephritis is suspected. However, the cornerstones of the diagnoses are renal biopsy and careful examination of the complement abnormality. Differential diagnostics between the various forms of GN is not possible based on clinical features, as they may vary greatly. This review describes the known mechanisms of complement dysfunction leading to different forms of primary GN (like IgA glomerulonephritis, dense deposit disease, C3 glomerulonephritis, post-infectious GN, membranous GN) and differences to atypical hemolytic uremic syndrome. It also covers the basic elements of etiology-directed therapy and prognosis of the most common forms of GN. Common principles in the management of GN include treatment of hypertension and reduction of proteinuria, some require immunomodulating treatment. Complement inhibition is an emerging treatment option. A thorough understanding of the basic disease mechanism and a careful follow-up are needed for optimal therapy.

C4 nephritic factor in patients with immune-complex-mediated membranoproliferative glomerulonephritis and C3-glomerulopathy

BACKGROUND

Acquired or genetic abnormalities of the complement alternative pathway are the primary cause of C3glomerulopathy(C3G) but may occur in immune-complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) as well. Less is known about the presence and role of C4nephritic factor(C4NeF) which may stabilize the classical pathway C3-convertase. Our aim was to examine the presence of C4NeF and its connection with clinical features and with other pathogenic factors.

RESULTS

One hunfe IC-MPGN/C3G patients were enrolled in the study. C4NeF activity was determined by hemolytic assay utilizing sensitized sheep erythrocytes. Seventeen patients were positive for C4NeF with lower prevalence of renal impairment and lower C4d level, and higher C3 nephritic factor (C3NeF) prevalence at time of diagnosis compared to C4NeF negative patients. Patients positive for both C3NeF and C4NeF had the lowest C3 levels and highest terminal pathway activation. End-stage renal disease did not develop in any of the C4NeF positive patients during follow-up period. Positivity to other complement autoantibodies (anti-C1q, anti-C3) was also linked to the presence of nephritic factors. Unsupervised, data-driven cluster analysis identified a group of patients with high prevalence of multiple complement autoantibodies, including C4NeF.

CONCLUSIONS

In conclusion, C4NeF may be a possible cause of complement dysregulation in approximately 10-15% of IC-MPGN/C3G patients.

A case report of recurrent membranoproliferative glomerulonephritis after kidney transplantation due to ventriculoatrial shunt infection

Background

Transplant failure requires the consideration of numerous potential causes including rejection, acute tubular necrosis, infection, and recurrence of the original kidney disease. Kidney biopsy is generally required to approach these differential diagnoses. However, the histopathological findings on their own do not always lead to a definite diagnosis. Consequently, it is crucial to integrate them with clinical findings and patient history when discussing histopathological patterns of injury. The histopathologic finding of a membranoproliferative glomerulonephritis (MPGN) is one of the most challenging constellations since it does not refer to a specific disease entity but rather reflects a pattern of injury that is the result of many different causes. Whilst MPGN is occasionally classified as immune complex mediated, careful evaluation usually reveals an underlying disorder such as chronic infection, plasma cell dyscrasia, complement disorders, and autoimmune disease.

Case presentation

We describe the case of a 43-year-old woman who was referred to us because of a slowly rising serum creatinine 4 years after kidney transplantation. As in the native kidney, the biopsy revealed an MPGN pattern of injury. The cause of this finding had not been established prior to transplantation leading to a classification as idiopathic MPGN in the past. Further workup at the time of presentation and allograft failure revealed chronic infection of a ventriculoatrial shunt as the most probable cause.

Conclusion

This case underlines the fact that MPGN is not a disease but a histopathological description. Consequently, the causative disorder needs to be identified to avoid kidney failure and recurrence after transplantation.

Autoimmune abnormalities of the alternative complement pathway in membranoproliferative glomerulonephritis and C3 glomerulopathy

Membranoproliferative glomerulonephritis (MPGN) is a rare chronic kidney disease associated with complement activation. Recent immunofluorescence-based classification distinguishes between immune complex (IC)-mediated MPGN, with glomerular IgG and C3 deposits, and C3 glomerulopathies (C3G), with predominant C3 deposits. Genetic and autoimmune abnormalities causing hyperactivation of the complement alternative pathway have been found as frequently in patients with immune complex-associated MPGN (IC-MPGN) as in those with C3G. In the last decade, there have been great advances in research into the autoimmune causes of IC-MPGN and C3G. The complement-activating autoantibodies called C3-nephritic factors (C3NeFs), which are present in 40-80% of patients, form a heterogeneous group of autoantibodies that stabilise the C3 convertase or the C5 convertase of the alternative pathway or both. A few patients, mainly with IC-MPGN, carry autoantibodies directed against the two components of the alternative pathway C3 convertase, factors B and C3b. Finally, autoantibodies against factor H, the main regulator of the alternative pathway, have been reported in a small proportion of patients with IC-MPGN or C3G. The identification of distinct pathogenetic patterns leading to kidney injury and of targets in the complement cascade may pave the way for tailored therapies for IC-MPGN and C3G, with specific complement inhibitors in the development pipeline.

A novel mutation in complement 2 accompanied by susceptibility variants in C3 glomerulonephritis: A case study

BACKGROUND

C3 glomerulonephritis is a rare, chronic disease characterized by C3c-dominant staining on renal biopsy and is caused by inherited or acquired alternative complement pathway dysregulation.

CASE PRESENTATION

Here, we reported a 36-year-old man presenting with nephritic syndrome and normal renal function. Secondary causes were excluded by detailed clinical history and laboratory tests. His renal biopsy was consistent with C3 glomerulonephritis with a membranoproliferative glomerulonephritis pattern. To identify the etiology, we carried out genetic and autoantibody screening tests. The results showed he was negative for autoantibodies, while the next-generation sequencing revealed common variants of complement factor H (c.1204T>C; p.Tyr402His), (c.184G>A; p.Val62Ile) and thrombomodulin (c.1418C>T; p.Ala473Val), which have previously been reported to increase susceptibility to complement-mediated diseases. He also carried complement factor H (c.2808G>T; p.Glu936Asp) and mannose-binding lectin (c.161G>A; p.Gly54Asp), putting the patient at an increased risk of infections, which was an important trigger for C3 glomerulonephritis. A novel variant of complement 2 (c.53A>G; p.His18Arg) that might contribute to the occurrence of C3 glomerulonephritis when combined with these susceptibility variants was further identified. The patient was treated with ramipril and regular fresh frozen plasma infusion. He had a good response to treatment with well-controlled proteinuria, stable renal function and an increasing serum C3 level.

CONCLUSIONS

This case adds insight into the pathogenesis of C3 glomerulopathy by showing that a combination of susceptibility variants, genetic mutations and triggers might be responsible for the clinical and pathological phenotypes.

Effectiveness of cryofiltration and mizoribine combination with oral steroid therapy in a patient with membranoproliferative glomerulonephritis due to essential cryoglobulinemia

A 65-year-old male patient with nephrotic syndrome was admitted to our hospital due to worsening systemic edema and purpura on the limbs. He had an impaired renal function, low serum complement level, and elevated rheumatoid factor level. He was positive for cryoglobulin (monoclonal IgM-κ and polyclonal mixed-type IgG), and the results of his kidney biopsy showed a tissue profile of membranoproliferative glomerulonephritis (MPGN). Due to the fact that the secondary cause was unclear, he was diagnosed with MPGN due to essential mixed cryoglobulinemia. On hospital day 20, he was initiated on 50 mg/day prednisolone (PSL). On hospital day 43, oral mizoribine (MZR) at a dose of 150 mg/day was prescribed. On hospital day 49, cryofiltration was performed because the disease was steroid resistant. The treatment promptly decreased urine protein levels. Serum albumin and serum complement levels increased, and complete remission was achieved approximately three months after the initiation of treatment. The PSL and MZR doses were gradually reduced to 2 mg/day and 100 mg/day, respectively, without any reemergence of the symptoms of cryoglobulinemia or relapse of the nephrotic syndrome for three years. Here, we report this case with essential mixed cryoglobulinemia in whom we could achieve complete remission of the disease by adding cryofiltration to the oral corticosteroid and immunosuppressant therapy with mizoribine and could maintain for a long time.

Characteristics of membranoproliferative glomerulonephritis based on a new classification at a single center

BACKGROUND

Recently, a new classification has been established for membranoproliferative glomerulonephritis (MPGN). However, the effect of the new classification on MPGN treatment is not fully understood.

METHODS

We conducted a retrospective study of 87 patients with biopsies diagnosed as MPGN. We reclassified 87 MPGN patients diagnosed between 1977 and 2014 at our hospital, according to the new classification, and analyzed both primary immune complex (IC)- and Alternative pathway (AP)-mediated MPGN [corrected] in terms of clinicopathological features, treatment, and renal prognosis.

RESULTS

Proteinuria was abundant in the IC-mediated MPGN group (p = 0.0063), and the serum albumin level was significantly lower in the IC-mediated MPGN group (p = 0.0186). The serum C3 value was significantly lower in the CP-mediated MPGN group (p = 0.0317). Serum CH50 values were also lower in the CP-mediated MPGN group (p = 0.0404). However, glomerular deposition of C3 showed no significant differences in immunofluorescence findings. The 148.6-month renal survival rate was similar in both groups (p = 0.445).

CONCLUSION

These results suggested no significant differences in complement activation of the solid phase in local glomeruli and therefore equivalent in renal prognosis [corrected].

Retinal manifestations in patients with complement-mediated membranoproliferative glomerulonephritis

Complement-mediated membranoproliferative glomerulonephritis is a rare progressive glomerular disease. In some patients it can be associated with retinal lesions. Therefore, the purpose of this study was to assess a case series with this diagnosis in our hospital. A cross-sectional study was conducted on 8 patients diagnosed with complement-mediated membranoproliferative glomerulonephritis. Funduscopy, optical coherence tomography (OCT) and Swept Source domain OCT angiography were performed. Only 1 of the 8 patients showed drusen-like deposits that were located under the retinal pigment epithelium in the OCT, with the presence of associated choroidal neovascularization being ruled out in OCT angiography. Therefore, membranoproliferative glomerulonephritis may produce retinal alterations with drusen or retinal pigment epithelium detachment, and requires an appropriate differential diagnosis to be made with age-related macular degeneration. The follow-up of these patients is important in order to detect vision-threatening complications.

An extranodal histopathological analysis of idiopathic multicentric Castleman disease with and without TAFRO syndrome

Thrombocytopenia, anasarca, fever, renal failure or reticulin fibrosis, and organomegaly (TAFRO) syndrome, a poor prognostic clinical condition showing similar histopathological findings to idiopathic multicentric Castleman disease (iMCD), has been reported in Japan. In our previous report, a clinicopathological analysis was performed on 70 nodal cases of iMCD with/without TAFRO. iMCD is classified into three types based on histopathology: (i) plasmacytic (PC), (ii) mixed, and (iii) hypervascular (hyperV). In this report, extranodal histopathological changes of iMCD with/without TAFRO were analyzed. Regarding the kidney pathology, we observed the proliferation of mesangial cells with positive staining of interleukin-6 (IL-6), consistent with membranoproliferative glomerulonephritis, in two cases of iMCD with TAFRO. The number of megakaryocytes per high-powered fields was not significantly different between iMCD cases with and without TAFRO. In conclusion, extranodal lesions of iMCD with/without TAFRO showed various interesting histopathological findings. These lesions may therefore be related to the clinical condition of TAFRO. Obtaining further knowledge about TAFRO will require the observation of nodal as well as extranodal lesions.

IgA-dominant glomerulonephritis with a membranoproliferative pattern of injury

Immunoglobulin A (IgA)-dominant membranoproliferative glomerulonephritis (MPGN) is a descriptive term for renal biopsies in which differential diagnoses of unusual IgA nephropathy (IgAN), infection-related GN, or other etiologies are considered. We sought to understand clinical and pathologic features of this finding. Native kidney biopsies with IgA-dominant immune deposits and diffuse MPGN features without significant exudative features or subepithelial deposits were retrospectively reviewed. Two groups (n = 27, 33 biopsies) were identified: patients with chronic liver disease and those without. Patients without chronic liver disease (n = 15) were men (73%, age 40) who presented with nephrotic-range proteinuria, hematuria, renal insufficiency, negative serologic studies, and no history of infection. At a median interval of 3 years, 11 had available follow-up information. Three (27%) progressed to end-stage renal disease. One had recurrent IgA-dominant GN in the renal allograft less than 1 year posttransplant. Four of 5 patients with repeat biopsies had persistent IgA-dominant MPGN. Patients with chronic liver disease (n = 12) had similar biopsy findings, but 42% had concurrent infections, some occult. At a median interval of 7 weeks, 8 patients (80% of those with follow-up) had died and 2 were dialysis dependent. In conclusion, IgA-dominant MPGN was seen in 2 clinical cohorts in this study. In patients without chronic liver disease, this appears to represent either a unique clinicopathologic entity with a poorer prognosis than IgAN or an aggressive variant of IgAN. Patients with chronic liver disease often have underlying infection, and regardless of treatment, die within 1 year because of complex medical conditions.

Membranoproliferative glomerulonephritis in a patient with chronic brucellosis

Brucellosis is the most common zoonotic disease in Greece, with an endemic distribution and can affect any organ. Infiltration of the renal parenchyma causes acute and chronic interstitial nephritis with granulomas, whereas renal glomeruli are rarely affected. The disease has been sporadically reported, and it causes various histopathologic patterns. Herein, we describe the case of a 39-year-old stock breeder with a history of recurrent episodes of bacteremia caused by Brucella melitensis over a period of 3 years. Two months after the last episode of bacteremia, he presented with mild renal insufficiency, nephrotic range proteinuria, and microscopic hematuria. A renal biopsy revealed membranoproliferative glomerulonephritis with a pattern of focal-segmental nodular sclerosis and moderate tubulointerstitial fibrosis. The patient received antimicrobial and corticosteroid therapy with partial remission of the nephrotic syndrome.

Complement your knowledge with a rare cause of pauci-immune glomerulonephritis

RPGN can be subdivided into three categories on an immunopathologic basis: pauci-immune glomerulonephritis (PIGN), anti-glomerular basement membrane glomerulonephritis (anti-GBM disease), or immune complex-mediated glomerulonephritis (GN). PIGN is the most common cause of RPGN (80% of cases). The most common etiology of PIGN is anti-neutrophil cytoplasmic antibody (ANCA)-associated GN, which accounts for up to 90% of PIGN. PIGN is unique in that few to no immunoglobulin deposits are seen on glomerular immunofluorescence (IF) and electron microscopy (EM), but it is important to remember that dysregulation of the alternative pathway may result in the deposition of complements leading to inflammatory injury even in PIGN. Membranoproliferative glomerulonephritis (MPGN) is a rare, primary glomerular disorder. Both ANCA-associated GN and complement-mediated MPGN will lack immunoglobulin staining on immunofluorescence (IF) and thus present as PIGN on pathologic examination. This may lead to occurrences where these entities mimic one another, therefore necessitating heightened suspicion and close pathologic examination of a renal biopsy with electron microscopy to differentiate the diagnoses. This case highlights a rare case of C3 GN mimicking ANCA-associated GN.

Proliferative glomerulonephritis with monoclonal IgG deposits in children and young adults

BACKGROUND

Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) has been recognized as a distinct entity in recent years. To the best of our knowledge, all patients with PGNMID reported thus far were older than 20 years of age. We now report five cases of PGNMID in patients under 20 years of age.

METHODS

The clinical database was searched for patients with native kidney biopsies from 9/2011 to 8/2017, and cases with a diagnosis of PGNMID were retrieved. Light microscopy specimens and immunofluorescence and electron microscopy images were revisited. Clinical data and kidney biopsy findings for patients under the age of 20 were recorded.

RESULTS

Five (0.78%) of a total of 637 patients younger than 20 with native renal biopsies had a diagnosis of PGNMID, including three males and two females with an average age of 14 years old (range 10-19). All five patients presented with microscopic hematuria and proteinuria. Three patients were nephrotic and their C3 levels were low. All five cases showed a membranoproliferative pattern with abundant mesangial and subendothelial monoclonal IgG3 deposits (3 κ and 2 λ light chain, respectively). The patients were followed up to 56 months. Two patients had re-biopsies 28 and 18 months after initial diagnosis and both showed similar morphologic changes. Various treatments were attempted including prednisone, mycophenolate mofetil, tacrolimus, rituximab, and eculizmab, with mixed responses.

CONCLUSIONS

PGNMID does occur in children and young adults. Membranoproliferative glomerulonephritis pattern with monoclonal IgG3 deposits is a common feature. Despite various immunosuppressive treatments, the disease appears slowly progressive.

HCV-negative mixed cryoglobulinemia and kidney involvement: in-depth review on physiopathological and histological bases

Type II mixed cryoglobulinemia without evidence of HCV infection but rather with renal involvement has been occasionally described. The pathogenesis of cryoglobulinemic kidney disease is most likely related to immune complex deposition including cryoglobulins, and cryoaggregation after cold exposure could play a pivotal role in clinical expression of cryoglobulinemia. In these cases, acute kidney injury and proteinuria remain the most frequent clinical expression of a cryoglobulinemic glomerulonephritis. Type II cryoglobulinemia with the laboratory finding of both monoclonal and polyclonal cryoglobulins is the most prevalent bio-humoral pattern among HCV-negative phenotypes with renal involvement, while type III cryoglobulinemia with polyclonal Ig is rare. Histological data in renal biopsies support the hypothesis that regardless of the HCV status cryoglobulinemia vasculitis share the same frequent pathological finding of membranoproliferative glomerulonephritides, but other histological patterns have also been observed in a minority of cases. In HCV-negative mixed cryoglobulinaemia, the paraneoplastic origin of the immune dysfunction should be ruled out and sporadic cases have been reported, while there is no cumulative evidence on the prevalence of these tumour-associated manifestations. Moving from the classification criteria and the etiopathogenesis of mixed cryoglobulinaemia, we provide a comprehensive review of the literature on the appearance of the disease with kidney injury in association with malignancies or autoimmune disorders without HCV coexistence.

A patient presenting with isolated hematuria and renal dysfunction as rare manifestation of cryoglobulinemic glomerulonephritis in the course of autoimmune diseases including Sjögren's syndrome

Autoimmune diseases are sometimes associated with immune-mediated renal diseases and cryoglobulinemia is one of the causes. Cryoglobulinemia and cryoglobulinemic glomerulonephritis associated with primary Sjögren's syndrome are most frequent condition among non-hepatitis C virus-related condition. Its typical renal manifestation shows high amount of proteinuria with microscopic hematuria and renal insufficiency. We describe a case of 72-year-old woman with Hashimoto disease, autoimmune hepatitis, Sjögren's syndrome, and immune-related pancytopenia complicated by cryoglobulinemic glomerulonephritis. Before kidney biopsy, tubulointerstitial nephritis probably due to Sjögren's syndrome was suspected because of persistent hematuria without significant proteinuria and developing mild renal dysfunction over 6 months. The developing renal dysfunction associated with isolated hematuria is uncommon in glomerular diseases. Kidney biopsy, however, revealed established membranoproliferative glomerulonephritis with subendothelial deposits consisting of tubular structures with IgM, IgG, and C3 staining. Corticosteroids plus mycophenolate mofetil therapy successfully normalized renal function. Physician should not overlook cryoglobulinemic glomerulonephritis, which is potentially poor prognosis, even if urinalysis shows only persistent isolated hematuria in patients with autoimmune diseases.

The PD-1/PD-L1 Inhibitory Pathway is Altered in Primary Glomerulonephritides

The pathogenesis of primary proliferative and non-proliferative glomerulonephritides (PGN and NPGN) is still not fully understood, however, current evidence suggests that most cases of PGN and NPGN are the results of immunologic response to different etiologic agents that activates various biological processes leading to glomerular inflammation and injury. Programmed cell death protein 1 (PD-1) is the major inhibitory receptor regulating T cell exhaustion. The aim of this study was to evaluate the frequencies of PD-1-positive and PD-ligand 1 (PD-L1)-positive T and B lymphocytes in patients with NPGN and PGN in relation to clinical parameters for the first time. The study included peripheral blood (PB) samples from 20 newly diagnosed PGN and NPGN patients. The control group comprised of 20 healthy age- and sex-matched subjects. The viable PB lymphocytes underwent labelling with fluorochrome-conjugated monoclonal antibodies anti-PD-1 and anti-PD-L1, and were analyzed using a flow cytometer. The frequencies of CD4+/PD1+ T lymphocytes, CD8+/PD1+ T lymphocytes, and CD19+/PD-1+ B lymphocytes in the PGN group exceeded values obtained both in the NPGN group, and the control group. Alteration of PD-1/PD-L1 pathway may be involved in poorer prognosis, as patients with PGN are characterized by higher frequencies of PD-1-positive and PD-L1-positive T and B lymphocytes than patients with NPGN. Our results suggest that deregulation of PD-1/PD-L1 axis may contribute to the PGN and NPGN pathogenesis. High percentages of lymphocytes with PD-1 and PD-L1 expression may be related to the continuous T-cell activation and development of glomerular inflammation and injury.

[Renal involvement of cryoglobulinemia]

Cryoglobulins are immunoglobulins that undergo reversible precipitation at low temperatures. They can induce systemic vasculitis, characterized by purpuric cutaneous lesions, arthritis, peripheral neuropathy, hypocomplementemia and glomerular disease. Renal pathology reveals membranoproliferative glomerulonephritis, with particularly intense mesangial cell proliferation and infiltration by macrophages, associated with intracapillary thrombi. This renal disease presents as a nephritic syndrome, with heavy proteinuria, haematuria severe hypertension and rapidly progressive kidney failure that can lead to end-stage renal disease. Hepatitis C is the main cause of mixed (type 2 or 3) cryoglobulinemia and requires the initiation of a specific antiviral therapy, together with immunosuppressive drugs. Rituximab is now considered as the best immunosuppressive therapy in this situation, inducing B-cell depletion, clearance of circulating cryoglobulin and resolution of renal symptoms. Monoclonal (type 1) cryoglobulinemia, is a rare condition, but it usually reveals an B-cell or a plasma cell proliferation, that require a specific hematological treatment to obtain remission of the renal disease.