Pathologic differentiation between lupus and nonlupus membranous glomerulopathy

Lupus-like membranous nephropathy during the postpartum period expressing glomerular antigens exostosin 1/exostosin 2 and phospholipase A2 receptor: a case report

Recently, several target antigens of membranous nephropathy (MN), such as phospholipase A2 receptor (PLA2R) and exostosin 1/exostosin 2 (EXT1/2), have been discovered. A 30-year-old woman was referred to our hospital with nephrotic range proteinuria and microscopic hematuria. She was first noted to have proteinuria before pregnancy, and her proteinuria worsened in the postpartum period. A renal biopsy showed MN. Immunofluorescence microscopy showed IgG, IgA, IgM, C3, C4, and C1q depositions in the mesangial area and glomerular capillary walls (GCWs). Regarding the IgG subclass, IgG1 and IgG3 were detected on glomeruli. Electron microscopy showed subepithelial electron-dense deposits (EDDs). EDDs were also detected in paramesangial and subendothelial areas. The diagnosis of membranous lupus nephritis (MLN) was suspected, but she did not fulfill the criteria for systemic lupus erythematosus. Neither anti-nuclear antibody nor hypocomplementemia were detected. We further evaluated glomerular EXT1/2 expressions, which were evident on GCWs. In addition, PLA2R was also detected on GCWs, although serum antibody for PLA2R was negative. She responded to immunosuppressive therapy with decreased proteinuria. In the present case, glomerular PLA2R expression implied the possibility of primary MN. However, pathological findings with a full-house staining pattern and glomerular EXT1/2 expressions were very similar to those of lupus-associated MN. Glomerular PLA2R expression appeared not to reflect immunocomplexes of PLA2R and autoantibody when considering the results for glomerular IgG subclass and the absence of serum anti-PLA2R antibody. Collectively, it is plausible that this was a case of a relatively young postpartum female who developed latent MLN rather than primary MN.

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.

Case report: Thrombotic thrombocytopenic purpura in a pregnant woman with lupus membranous nephropathy: a diagnostic challenge

A 27-year-old female at 20th week of pregnancy was admitted with edema, foamy urine, but normal blood pressure. Her blood count was normal, she had proteinuria of 3 g/day, creatinine 0.4 mg/dl, albumin 2.4 g/dl, and cholesterol 355 mg/dl. Antinuclear antibodies 1/160, but Anti-DNA, anticardiolipin antibodies and lupus anticoagulant were negative, with normal serum C3 and C4. A renal biopsy showed secondary membranous glomerulopathy, most likely lupus class V pure. Steroids, azathioprine, and aspirin were initiated, up to 28 weeks of pregnancy, when she developed severe hypertension, photopsia, headache, anasarca, extensive bruising of the extremities, severe anemia, thrombocytopenia, and creatinine rose to 2.09 mg/dl with preserved diuresis. A female infant, 1045 grams, was delivered by emergency caesarean section. Following the surgery, she experienced diplopia, dysarthria, bradypsychia, and sensory alterations in the lower extremities, necessitating emergency hemodialysis due to pulmonary congestion. Blood smear revealed schistocytes, LDH elevated at 1148 IU/L, while transaminases and liver function remained normal, suggesting thrombotic thrombocytopenic purpura. ADAMTS13 revealed 6% activity with the presence of inhibitor. Mycophenolate and daily plasmapheresis with fresh frozen plasma replacement yielded unsatisfactory response, unaffected by the addition of methylprednisolone pulses and rituximab. Eventually, intravenous cyclophosphamide was introduced, resulting in complete hematological remission and normalization of ADAMTS13, however dialysis-dependence persisted and four years later, right renal cancer prompted bilateral nephrectomy. After a total follow-up of six years, she remained free of neoplastic recurrence and lupus activity, receiving prednisone and hydroxychloroquine. The differential diagnosis of microangiopathic syndrome in a pregnant lupus patient is discussed.

A Diagnostic and Therapeutic Dilemma Concerning Exostosin 1/Exostosin 2-associated Lupus-like Membranous Nephropathy with Positive Antinuclear Antibody in an Elderly Man with Various Immune Abnormalities

Exostosin 1 (EXT1) and exostosin 2 (EXT2)-associated membranous nephropathy (MN) may be associated with active autoimmune disease. We encountered an elderly man who presented with EXT1/EXT2-associated lupus-like MN with full house immune deposits, monoclonal gammopathy of uncertain significance and Sjögren's syndrome. The patient exhibited various other immune abnormalities. Although he did not fulfill the criteria of clinical systemic lupus erythematosus (SLE), he met a stand-alone renal criterion of the Systemic Lupus International Collaborating Clinics (SLICC) 2012. Whether or not a stand-alone renal criterion with EXT1/EXT2 positivity, as in the present patient, can efficiently guide decisions regarding the diagnosis and treatment of SLE remains a clinical dilemma.

Non-Full House Membranous Lupus Nephritis Represents a Clinically Distinct Subset

Key Points

Non-full house (NFH) membranous lupus nephritis (MLN) is a minor subset of all MLN cases. Patients with NFH MLN tend to be older when diagnosed with systemic lupus erythematosus, undergo first renal biopsy at an older age, and have fewer extrarenal systemic manifestations. Lower load of C3 glomerular deposits seen in NFH MLN biopsies suggests attenuation of complement-mediated injury, which may have wider systemic implications.

Background

Renal involvement in systemic lupus erythematosus (SLE) is a key predictor of morbidity and mortality. Immunofluorescence (IF) staining of glomeruli is typically positive for IgG, IgA, IgM, C3, and C1q—the full house (FH) pattern. However, a subset of patients with membranous lupus nephritis (MLN) have a Non-FH (NFH) IF pattern more typical of idiopathic membranous nephropathy.

Methods

From a multi-institutional cohort of 113 MLN cases, we identified 29 NFH MLN biopsies. NFH MLN was defined by IF criteria: ≥1+ glomerular capillary loop IgG staining and<1+ IgA, IgM, and C1q. FH MLN was defined as ≥1+ staining for all five antibodies. Intermediate (Int) cases did not meet criteria for FH or NFH. We compared the pathological and clinical characteristics and outcomes among patients with FH, NFH, and Int IF patterns on kidney biopsy.

Results

NFH MLN represents a subset of MLN biopsies (13.4%). Compared with patients with FH MLN, patients with NFH MLN were older at SLE diagnosis (29 versus 22.5 years), had a longer time to initial kidney biopsy (8 versus 3.16 years), and had fewer SLE manifestations (2.5 versus 3.36 involved systems). NFH MLN biopsies showed lower C3 IF intensity (1.16+ versus 2.38+). Int biopsies had findings intermediate between those of NFH and FH groups.

Conclusions

NFH IF pattern defines a small subset of MLN biopsies and appears to be associated with milder clinical manifestations and slower disease progression. Less robust C3 deposition in NFH MLN may suggest a pathophysiology distinct from that of FH MLN.

Glomerular Disease in Liver Disease

Glomerular diseases are an important cause of kidney disease in patients with liver disease. Although kidney involvement due to tubular or vascular disease is more common, glomerular diseases became more prevalent as hepatitis infections increased and then subsequently decreased with the widespread availability of hepatitis A and B vaccines and the development of effective antiviral treatments for hepatitis B and C. In this review, we discuss the common glomerular pathologies that are seen in patients with liver disease and the current treatment options available to them.

The Prevalence of Mesangial Electron-Dense Deposits in PLA2R-Positive Membranous Nephropathy

INTRODUCTION

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults and can be primary or secondary. The antigenic target of antibodies in 70% of primary cases is phospholipase A2 receptor (PLA2R). The presence or absence of mesangial electron-dense deposits has been used to distinguish between primary and secondary MN. Mesangial deposits suggest MN due to lupus, infection, or other causes, though they are reported to occur in approximately 10% of primary MN. Staining for PLA2R is now frequently used for confirming a diagnosis of primary MN. If mesangial deposits predict a secondary cause, they should be more frequent in PLA2R-negative biopsies.

METHODS

A review of institutional kidney biopsies between March 2017 and June 2020 identified all cases of MN. Cases with a diagnosis of lupus or near "full-house" staining by immunofluorescence microscopy (IF) were excluded. Light microscopy, IF, and electron microscopy (EM) were performed. PLA2R staining was performed by IF. EM for all cases was reviewed and electron-dense deposit location, distribution, and size were determined.

RESULTS

Ninety-three cases of MN were identified, of which 86 had both PLA2R staining and EM performed. Of these, 51 cases (59%) were positive for PLA2R and 35 (41%) were negative. Mesangial electron-dense deposits were present in 22 (25.6%) of the 86 cases, including 27.5% (14/51) of PLA2R-positive cases and 22.8% (8/35) of PLA2R-negative cases. No difference was seen in size or distribution of deposits, or other features considered suggestive of secondary MN.

CONCLUSION

PLA2R-negative cases were not more likely to have mesangial deposits than PLA2R-positive cases. Mesangial deposits should not be used as an indicator of secondary MN.

Lupus Nephritis: The Significant Contribution of Electron Microscopy

Background

Systemic lupus erythematosus (SLE) represents a principal prototype of a multisystemic autoimmune disease with the participation of both cell- and antibody-mediated mechanisms causing significant renal impairment. A renal biopsy diagnosis is the gold standard for clinical renal disease in SLE, which includes a broad range of indications.

Summary

Renal disease in SLE can involve glomerular, tubulointerstitial, and/or vascular compartments, none of which are mutually exclusive. In most instances, the basic pathogenetic mechanism involves tissue deposition of immune complexes and/or cell-mediated mechanisms, identified by light microscopy, immunohistochemical methods, and electron microscopy (EM), evoking intraglomerular proliferative, inflammatory, and other tissue responses. These produce a spectrum of histologic lesions, depending on the participation of a wide range of clinical triggers, namely, genetic, serological, and immunological factors, correlating with their underlying pathogenetic potential. In addition to light and immunofluorescence microscopy, EM in this setting facilitates an accurate diagnosis, assesses disease activity, delineates subclasses, differentiates from primary forms of non-lupus renal lesions, identifies organized deposits, and rarely, identifies other forms of nonimmune complex lesions such as podocytopathies, amyloidosis, and thrombotic microangiopathy.

Key Messages

EM findings that are distinctive for most of the renal lesions in SLE include immune complex and nonimmune complex diseases as well as overlapping entities. Routine ultrastructural examination not only provides significant diagnostic and prognostic information from both initial and repeat renal biopsies from lupus patients but also contributes toward the understanding of the underlying pathophysiology of the disease process.

The Continuing Need for Electron Microscopy in Examination of Medical Renal Biopsies: Examples in Practice

Background

For the better part of the past 6 decades, transmission electron microscopy (EM), together with routine light microscopy and immunofluorescence and/or immunohistochemistry (IHC), has been an essential component of the diagnostic workup of medical renal biopsies, particularly native renal biopsies, with increasing frequency in renal allograft biopsies as well. Studies performed prior to the year 2000 have indeed shown that a substantial fraction of renal biopsies cannot be accurately diagnosed without EM. Still, EM remains costly and labor-intensive, and with increasing pressure to reduce healthcare costs, some centers are de-emphasizing diagnostic EM. This trend has been coupled with advances in IHC and other methods in renal biopsy diagnosis over the past 2-3 decades.

Summary

Nonetheless, it has been our experience that the diagnostic value of EM in the comprehensive evaluation of renal biopsies remains similar to what it was 20-30 years ago. In this review, we provide several key examples from our practice where EM was essential in making the correct renal biopsy diagnosis, ranging from relatively common glomerular lesions to rare diseases.

Key Messages

EM remains an important component of the diagnostic evaluation of medical renal biopsies. Failure to perform EM in certain cases will result in an incorrect diagnosis, with possible clinical consequences. We strongly recommend that tissue for EM be taken and stored in an appropriate fixative and ultrastructural studies be performed for all native renal biopsies, as well as appropriate renal allograft biopsies as recommended by the Banff consortium.

Lupus-like membranous nephropathy. Is it lupus? Report of 5 cases in a reference hospital in Mexico

INTRODUCTION

Lupus nephritis requires antinuclear antibodies as classification criteria. There is a group of patients with nephrotic syndrome and conclusive histopathological findings for lupus nephritis, without classification criteria for systemic lupus erythematosus (SLE) or extrarenal manifestations. These groups of patients have been described as "lupus-like" nephritis or "renal-limited lupus nephritis".

METHODS

Renal biopsy with histopathological evaluation with "full-house" immune-reactants in patients with negative antinuclear antibodies.

RESULTS

We report four cases with nephrotic syndrome and one with hematuria-proteinuria syndrome: two with impaired glomerular filtration rate and three with preserved renal function; urinary sediment with hematuria without dysmorphia and without extrarenal manifestations for autoimmune disease, negative antinuclear antibodies (ANA) and anti-double stranded DNA (anti-dsDNA); normal C3 and C4 complement levels. Renal biopsy in all cases was consistent for lupus nephritis class V. All patients received treatment as lupus nephritis protocol; only one case received induction with cyclophosphamide and methylprednisolone boluses, the rest received mycophenolic acid and prednisone as induction and maintenance. Two of the cases induced with mycophenolic acid relapsed, requiring cyclophosphamide for 6 months, achieving complete remission. All patients received renin-angiotensin-aldosterone system blockade and hydroxychloroquine. At follow-up, 4 cases still have negative antibodies and are without extrarenal manifestations for SLE classification criteria. The other case, during pregnancy several years after initial diagnosis, had preeclampsia with nephrotic proteinuria and a new determination of positive ANA and anti-dsDNA antibodies, complement levels below normal limits.

CONCLUSION

The follow-up of patients with membranous glomerulopathy must be close; lupus like nephritis may be the first manifestation of the disease.

Segmental membranous nephropathy

Most cases of membranous nephropathy (MGN) present with global and diffuse distribution of subepithelial deposits. However, segmental MGN, in which there is focal or diffuse segmental subepithelial deposits, are occasionally encountered. The clinical and pathologic significance of segmental MGN is not well understood and thought to be more likely due to either early or resolving phase of the global form of MGN. Several case reports and literature available suggest that it may be a manifestation of secondary causes based on pathologic features such as presence of C1q and mesangial deposits, extra-glomerular deposits involving tubular basement membranes, absence of PLA2R and THSD7A, IgG1 and IgG3 subclass dominance, and the presence of other co-existing renal disease. Other reports, however, suggest that some of these cases may be a variant of the primary form of MGN. In this review, we integrate what is known about segmental MGN in order to better direct interpretation of renal biopsies in which it is identified.

Biomarkers of Immune Activation and Incident Kidney Failure With Replacement Therapy: Findings From the African American Study of Kidney Disease and Hypertension

RATIONALE & OBJECTIVE

Immune activation is fundamental to the pathogenesis of many kidney diseases. Innate immune molecules such as soluble urokinase-type plasminogen activator receptor (suPAR) have been linked to the incidence and progression of chronic kidney disease (CKD). Whether other biomarkers of immune activation are associated with incident kidney failure with replacement therapy (KFRT) in African Americans with nondiabetic kidney disease is unclear.

STUDY DESIGN

Prospective cohort.

SETTING & PARTICIPANTS

African American Study of Kidney Disease and Hypertension (AASK) participants with available baseline serum samples for biomarker measurement.

PREDICTORS

Baseline serum levels of soluble tumor necrosis factor receptor 1 (sTNFR1), sTNFR2, tumor necrosis factor α (TNF-α), and interferon γ (IFN-γ).

OUTCOMES

Incident KFRT, all-cause mortality.

ANALYTICAL APPROACH

Cox proportional hazards models.

RESULTS

Among 500 participants with available samples, mean glomerular filtration rate was 44.7mL/min/1.73m², and median urinary protein-creatinine ratio was 0.09g/g at baseline. Over a median follow up of 9.6 years, there were 161 (32%) KFRT and 113 (23%) death events. In models adjusted for demographic and clinical factors and baseline kidney function, each 2-fold higher baseline level of sTNFR1, sTNFR2, and TNF-α was associated with 3.66-fold (95% CI, 2.31-5.80), 2.29-fold (95% CI, 1.60-3.29), and 1.35-fold (95% CI, 1.07-1.71) greater risks of KFRT, respectively; in comparison, each doubling of baseline suPAR concentration was associated with 1.39-fold (95% CI, 1.04-1.86) greater risk of KFRT. sTNFR1, sTNFR2, and TNF-α were also significantly associated with death (up to 2.2-fold higher risks per 2-fold higher baseline levels; P≤0.01). IFN-γ was not associated with either outcome. None of the biomarkers modified the association of APOL1 high-risk status (genetic risk factors for kidney disease among individuals of African ancestry) with KFRT (P>0.05 for interaction).

LIMITATIONS

Limited generalizability to other ethnic groups or causes of CKD.

CONCLUSIONS

Among African Americans with CKD attributed to hypertension, baseline levels of sTNFR1, sTNFR2, and TNF-α but not IFN-γ were associated with KFRT and mortality.

The clinicopathologic spectrum of segmental membranous glomerulopathy

Membranous glomerulopathy (MGN) is characterized by global subepithelial immune deposits that stain most intensely by immunofluorescence for IgG. Here we describe the clinical and pathologic findings in a cohort of patients with MGN in which, by definition, only segmental immune deposits are present. This rare variant, termed segmental MGN (sMGN), is poorly characterized. We retrospectively identified all patients with sMGN diagnosed at Columbia University from January 2010 to October 2018, excluding those with systemic lupus erythematosus. Data on presenting features, pathologic findings, and outcomes were collected. Fifty cases of sMGN were identified, representing 2.5% of MGN. In 21 of 50 biopsies, there was an alternative, predominant disease process. The remaining 29 patients with isolated sMGN had a median creatinine of 0.97 mg/dl, median 24-hour urine protein 3.1 g/day, and 32% had nephrotic syndrome. Staining for NELL-1 (a protein kinase C binding protein) was positive in five of 17 cases. Staining for PLA2R, THSD7A, and exostosin 1 (autoantigens in primary MGN) was negative in all biopsies evaluated. Ultrastructural evaluation revealed predominantly early stage sMGN (stage 1 or 1-2 in 14/29). Follow-up was available for 21 of the 29 patients with isolated sMGN (median 12 months), including seven who received immunosuppression (primarily glucocorticoids). During follow-up, 86% had stable/improved kidney function and 45% achieved complete while 15% achieved partial remission. Among the 15 patients with isolated sMGN without full nephrotic syndrome, only two received immunosuppression; nonetheless, 50% achieved complete while 21% achieved partial remission. Thus, sMGN is a rare PLA2R-negative variant of MGN with 29% NELL-1 positivity and favorable prognosis, even in the absence of immunosuppressive treatment.

Renal hypoplasia can be the cause of membranous nephropathy-like lesions

BACKGROUND

Renal hypoplasia (RH) is the most common cause of chronic kidney disease in children. In cases of RH, proteinuria is often induced by glomerular hypertrophy and hyperfiltration that is commonly associated with focal segmental glomerulosclerosis. This study reports the first case series of a possible association between RH and membranous nephropathy (MN).

METHODS

Of the 168 children with RH who visited our department between 1999 and 2017, five with overt proteinuria (≥ 1 g/gCr) underwent renal biopsy. We retrospectively reviewed the medical charts and analyzed biopsy specimens using light microscopy (LM), immunofluorescence (IF), and electron microscopy.

RESULTS

The five children (four boys and one girl) had a median age of 5.5 years at the time of renal biopsy. The median proteinuria was 4.23 g/gCr (range 1.46-14.25), median serum albumin, 2.9 g/dL (range 2.3-3.7), and median estimated glomerular filtration rate, 59.7 mL/min/1.73 m² (range 36.7-103.6). LM showed segmental spike formation and mesangial hypercellularity and IF study showed segmental granular immunoglobulin G (IgG) staining (IgG1 and IgG3 dominant) along the capillary loops in all five patients. Electron-dense deposits were observed in the subepithelial and mesangial areas. Thus, the pathological studies showed MN-like lesions in all patients.

CONCLUSION

Our study suggests that RH can be the cause of MN-like lesions.

Immune-Monitoring Disease Activity in Primary Membranous Nephropathy

Primary membranous nephropathy (MN) is a glomerular disease mediated by autoreactive antibodies, being the main cause of nephrotic syndrome among adult patients. While the pathogenesis of MN is still controversial, the detection of autoantibodies against two specific glomerular antigens, phospholipase A2 receptor (PLA₂R) and thrombospondin type 1 domain containing 7A (THSD7A), together with the beneficial effect of therapies targeting B cells, have highlighted the main role of autoreactive B cells driving this renal disease. In fact, the detection of PLA₂R-specific IgG4 antibodies has resulted in a paradigm shift regarding the diagnosis as well as a better prediction of the progression and recurrence of primary MN. Nevertheless, some patients do not show remission of the nephrotic syndrome or do rapidly recur after immunosuppression withdrawal, regardless the absence of detectable anti-PLA₂R antibodies, thus highlighting the need of other immune biomarkers for MN risk-stratification. Notably, the exclusive evaluation of circulating antibodies may significantly underestimate the magnitude of the global humoral memory immune response since it may exclude the role of antigen-specific memory B cells. Therefore, the assessment of PLA₂R-specific B-cell immune responses using novel technologies in a functional manner may provide novel insight on the pathogenic mechanisms of B cells triggering MN as well as refine current immune-risk stratification solely based on circulating autoantibodies.

Sensitivity and Specificity of Pathologic Findings to Diagnose Lupus Nephritis

BACKGROUND AND OBJECTIVES

In 2012, the Systemic Lupus International Collaborating Clinics proposed that lupus nephritis, in the presence of positive ANA or anti-dsDNA antibody, is sufficient to diagnose SLE. However, this "stand-alone" kidney biopsy criterion is problematic because the ISN/RPS classification does not specifically define lupus nephritis. We investigated the combination of pathologic features with optimal sensitivity and specificity for the diagnosis of lupus nephritis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Three hundred consecutive biopsies with lupus nephritis and 560 contemporaneous biopsies with nonlupus glomerulopathies were compared. Lupus nephritis was diagnosed if there was a clinical diagnosis of SLE and kidney biopsy revealed findings compatible with lupus nephritis. The control group consisted of consecutives biopsies showing diverse glomerulopathies from patients without SLE, including IgA nephropathy, membranous glomerulopathy, pauci-immune glomerulonephritis, membranoproliferative glomerulonephritis (excluding C3 GN), and infection-related glomerulonephritis. Sensitivity and specificity of individual pathologic features and combinations of features were computed.

RESULTS

Five characteristic features of lupus nephritis were identified: "full-house" staining by immunofluorescence, intense C1q staining, extraglomerular deposits, combined subendothelial and subepithelial deposits, and endothelial tubuloreticular inclusions, each with sensitivity ranging from 0.68 to 0.80 and specificity from 0.8 to 0.96. The presence of at least two, three, or four of the five criteria had a sensitivity of 0.92, 0.8, and 0.66 for the diagnosis of lupus nephritis, and a specificity of 0.89, 0.95, and 0.98.

CONCLUSIONS

In conclusion, combinations of pathologic features can distinguish lupus nephritis from nonlupus glomerulopathies with high specificity and varying sensitivity. Even with stringent criteria, however, rare examples of nonlupus glomerulopathies may exhibit characteristic features of lupus nephritis.

A case of membranous nephropathy diagnosed with lupus nephritis 11 years after onset

A 34-year-old female patient presented to our hospital with lower extremity edema and proteinuria during pregnancy. Renal biopsy was performed and the patient was diagnosed with nephrotic syndrome due to lupus-like membranous nephropathy. This diagnosis was reached upon as laboratory findings upon admission, wherein both anti-nuclear and anti-double-stranded DNA antibodies revealed negative, did not fulfill the criteria for systemic lupus erythematosus (SLE) proposed by the American College of Rheumatology (ACR) and the patient did not reveal any typical physical manifestations of SLE. Methylprednisolone pulse therapy was started followed by oral administration of prednisolone. Urinary protein excretion diminished after 1 year of treatment. Eleven years later, the same patient was admitted to our hospital again with relapse of nephrotic syndrome. Laboratory findings upon second admission, wherein both anti-nuclear and anti-double-stranded DNA antibodies revealed positive, fulfilled the ACR criteria. Renal biopsy was performed again, resulting in a diagnosis of lupus nephritis. Steroid therapy combined with administration of mycophenolate mofetil led to an incomplete remission. Immunofluorescence studies confirmed the presence of IgG, IgM, C3, and C1q in renal biopsy specimens both at first and second admissions. Furthermore, immunofluorescence studies confirmed the presence of IgG1–4 in the first biopsy and tubuloreticular inclusions (TRIs) were revealed using electron microscopy. The present case represents the possibility that characteristic pathological findings of lupus nephritis, including TRIs, can reveal themselves before a diagnosis of SLE.

Paraneoplastic systemic lupus erythematosus associated with colorectal cancer

A 64-year-old gentleman initially presented with nephrotic syndrome and membranous nephropathy with positive staining for C1q, which was suspicious for lupus membranous nephritis. Investigation led to the simultaneous diagnosis of colorectal cancer (CRC). The CRC was surgically excised and the patient’s nephrotic syndrome resolved. The patient subsequently presented with classic systemic lupus erythematosus (SLE) including positive serological markers, mouth-ulcers and a photosensitive maculopapular rash. Two months later the patient represented with an SLE flare encompassing the full-hand of renal-pulmonary syndrome and vasculitic-neuropathy, importantly at this presentation occult recurrence of CRC was proven with tissue biopsy. Major histocompatibility class II haplotyping demonstrated HLA-DRB1*03, a known predisposition for SLE. This case depicts the scenario of tumour transformation triggering SLE development in a predisposed individual after an initial paraneoplastic manifestation in the form of membranous nephropathy (plus C1q). This supports the potential role of tumourgenesis in the development of SLE in a primed individual.

Antibodies to M-type phospholipase A2 receptor (PLA2R) in membranous lupus nephritis

BACKGROUND

Antibodies to M-type phospholipase A2 receptor (a-PLA₂R) have been identified in most patients with idiopathic membranous nephropathy, but the prevalence in membranous lupus nephritis (MLN) is still unclear. The objective of this study was to assess the prevalence of a-PLA₂R antibodies in a large cohort of patients with lupus nephritis.

METHODS

a-PLA₂R antibodies were measured by ELISA in serum from patients with systemic lupus erythematosus ( n = 190), of whom 37 had a biopsy-proven MLN. Positive samples were confirmed by commercial ELISA kit, Western blot and immunohistochemistry in renal tissue.

RESULTS

A total of 10 from 190 patients (5.3%) with systemic lupus erythematosus had circulating a-PLA₂R measured by in-house ELISA assay. The antibodies were detected in 7 patients with MLN (18.9%) and 3 patients with non-renal lupus disease (3.2%). PLA₂R staining was detected in the kidney biopsy of 5 of the 7 (71.4%) patients with MLN. a-PLA₂R levels were associated with active disease but not proteinuria levels. Presence of a-PLA₂R antibodies at baseline was associated with worse remission rates and longer time to remission compared to those patients serologically negative.

CONCLUSIONS

a-PLA₂R antibodies can be detected with low prevalence in MLN patients, but their detection is associated with a worse renal prognosis.

Primary membranous nephropathy: comprehensive review and historical perspective

Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in non-diabetic Caucasian adults over 40 years of age. It has an estimated incidence of 8–10 cases per 1 million. Fifty per cent of patients diagnosed with primary MN continue to have nephrotic syndrome and 30% of patients may progress to end-stage renal disease over 10 years. Although it was recognised as a distinct clinic-pathological entity in 1940s by immunofluorescence and electron microscopy, the pathogenesis and treatment have become more apparent only in the last decade. Discovery of M-type phospholipase A2 receptor (PLA2R) antibodies and thrombospondin type 1 domain-containing 7A antibodies has given new perspectives in understanding the pathogenesis of the disease process. Anti-PLA2R antibody is the first serologic marker that has promising evidence to be used as a tool to prognosticate the course of the disease. More importantly, therapeutic agents such as rituximab and adrenocorticotropic hormone analogues are the newer therapeutic options that should be considered in the therapy of primary MN.

Pediatric lupus nephritis

Involvement of the kidneys by lupus nephritis (LN) is one of the most severe clinical manifestations seen in individuals with systemic lupus erythematosus (SLE). LN is more frequent and severe in pediatric patients and has been associated with higher morbidity and mortality rates. This narrative review aimed to describe the general aspects of LN and its particularities when affecting children and adolescents, while focusing on the disease's etiopathogenesis, clinical manifestations, renal tissue alterations, and treatment options.

Full-house glomerular deposits: beware the sheep in wolf's clothing

The 2012 Systemic Lupus International Collaborating Clinics criteria propose the classification of systemic lupus erythematosus (SLE) by biopsy-confirmed lupus nephritis plus circulating antinuclear antibody or anti-double-stranded DNA antibody. Application of this stand-alone renal criterion to a cohort of patients with "full-house" glomerular deposits resulted in mistaken classification of SLE in some cases with antinuclear antibody. More precise biopsy criteria using a constellation of characteristic features are needed to optimize the kidney biopsy standard for lupus nephritis.

Clinicopathological features of atypical membranous nephropathy with unknown etiology in adult Chinese patients

Membranous nephropathy is typically classified as idiopathic and secondary, but nowadays the number of atypical membranous nephropathy (aMN) is increasing, many of which cannot determine its etiology in China. In this study, we compared the clinical and pathological characteristics of idiopathic membranous nephropathy (iMN) with aMN with unknown etiology from a single center in China.We retrospectively reviewed the clinical data of 577 patients with iMN and aMN at Peking University People's Hospital from January 2006 to December 2015 over a 10-year period, and analyzed their clinical and pathological characteristics. The level of serum phospholipase A2 receptors (PLA2R) antibody was detected in 106 iMN and 162 aMN patients.There were 278 iMN patients and 299 aMN patients who were included into this study in 3210 cases of renal biopsy during a 10-year period in our hospital. The average age of patients with iMN was significantly older than those with aMN (54.77 ± 13.01 vs 47.13 ± 16.16, P < .001). Around 75 patients (27%) were smokers in iMN patients, and 111 patients (37.1%) in aMN patients (P = .009). The mainly clinical manifestation of these 2 groups was nephrotic syndrome (61.5% in iMN group vs 58.4% in aMN group), but there were more patients accompanied with nephritis syndrome in aMN group than iMN group (17.1% vs 6.1%, P < .001). The immunofluorescence of renal biopsy showed "full house" in aMN group; and IgG subclass of the glomeruli demonstrated IgG4 (90.4%) was commonest in iMN group, but IgG1 (94.6%) in aMN group. 51 (48.1%) patients with iMN were detected positive PLA2R antibody in their serum, and 93 (57.4%) in aMN patients (P = .168). The patients with positive PLA2R antibody had higher positive rate of microscopic hematuria and urinary protein, lower albumin.The aMN patients are younger, higher smoking rate, its main clinical manifestation is nephrotic syndrome, but more of them accompanied with nephritis syndrome than those in iMN patients. Serum PLA2R antibody could not distinguish aMN from iMN. aMN could be a special glomerular disease in China, and need a further research on a larger scale.

Dissecting the relationships of IgG subclasses and complements in membranous lupus nephritis and idiopathic membranous nephropathy

Membranous lupus nephritis (MLN) and idiopathic membranous nephropathy (IMN) are kidney diseases with similar morphology, but distinct etiologies, both producing glomeruli with immune deposits. Immunoglobulins and complements, the main components of the deposits, can be detected by immunofluorescence (IF) microscopy. Previous researches characterized the immune deposits only individually, but not the interactions between them. To study these relationships we analyzed an IF profile of IgG subclasses and complements (IgG1, IgG2, IgG3, IgG4, C3, C1q, and C4) in 53 and 95 cases of biopsy-confirmed MLNs and IMNs, respectively, mainly using information theory and Bayesian networks. We identified significant entropy differences between MLN and IMN for all markers except C3 and IgG1, but mutual information (a measure of mutual dependence) were not significantly different for all the pairs of markers. The entropy differences between MLN and IMN, therefore, were not attributable to the mutual information. These findings suggest that disease type directly and/or indirectly influences the glomerular deposits of most of IgG subclasses and complements, and that the interactions between any pair of the markers were similar between the two diseases. A Markov chain of IgG subclasses was derived from the mutual information about each pair of IgG subclass. Finally we developed an integrated disease model, consistent with the previous findings, describing the glomerular immune deposits of the IgG subclasses and complements based on a Bayesian network using the Markov chain of IgG subclasses as seed. The relationships between the markers were effectively explored by information theory and Bayesian network. Although deposits of IgG subclasses and complements depended on both disease type and the other markers, the interaction between the markers appears conserved, independent from the disease type. The disease model provided an integrated and intuitive representation of the relationships of the IgG subclasses and complements in MLN and IMN.

Lupus nephritis: When and how often to biopsy and what does it mean?

Renal disease is a frequent complication of SLE which can lead to significant illness and even death. Today, a baseline renal biopsy is highly recommended for all subjects with evidence of lupus nephritis. Biopsy allows the clinician to recognize and classify different forms of autoimmune lupus glomerulonephritis, and to detect other glomerular diseases with variable pathogenesis which are not directly related to autoimmune reactivity, such as lupus podocytopathy. Moreover, not only glomerular diseases, but other severe forms of renal involvement, such as tubulo-interstitial nephritis or thrombotic microangiopathy may be detected by biopsy in lupus patients. Thus, an accurate definition of the nature and severity of renal involvement is mandatory to assess the possible risk of progression and to establish an appropriate treatment. The indications to repeat biopsy are more controversial. Some physicians recommend protocol biopsies to recognize the possible transformation from one class to another one, or to identify silent progression of renal disease, others feel that good clinical monitoring is sufficient to assess prognosis and to make therapeutic decisions. At any rate, although any decision should always be taken by considering the clinical conditions of the patient, there are no doubts that repeat renal biopsy may represent a useful tool in difficult cases to evaluate the response to therapy, to modulate the intensity of treatment, and to predict the long-term renal outcome both in quiescent lupus and in flares of activity.

Overview of IgG4-Related Tubulointerstitial Nephritis and Its Mimickers

Tubulointerstitial nephritis (TIN) is the most common form of renal involvement in IgG4-related disease. It is characterized by a dominant infiltrate of IgG4-positive plasma cells in the interstitium and storiform fibrosis. Demonstration of IgG4-positive plasma cells is essential for diagnosis, but the number of IgG4-positive cells and the ratio of IgG4-positive/IgG-positive plasma cells may vary from case to case and depending on the methods of tissue sampling even in the same case. IgG4-positive plasma cells can be seen in TIN associated with systemic lupus erythematosus, Sjögren syndrome, or anti-neutrophil cytoplasmic antibody–associated vasculitis, which further add diagnostic confusion and difficulties. To have a more clear view of IgG4-TIN and to delineate differential points from other TIN with IgG4-positive plasma cell infiltrates, clinical and histological features of IgG4-TIN and its mimickers were reviewed. In the rear part, cases suggesting overlap of IgG4-TIN and its mimickers and glomerulonephritis associated with IgG4-TIN were briefly described.

Management of Membranous Nephropathy in Western Countries

BACKGROUND

Idiopathic membranous nephropathy (IMN) is a common cause of nephrotic syndrome (NS) in adults in Western countries. In 2012, the KDIGO (Kidney Disease: Improving Global Outcomes) working group published guidelines for the management of glomerulonephritis, thus providing a template for the treatment of this condition. While being aware of the impact of the clinicians' acumen and that patients may choose a different therapeutic option due to the risks of specific drugs and also of the evolving guidelines, this review details our approach to the management of patients with IMN in a Western center (Toronto).

SUMMARY

Based on studies published in Europe and North America, we included recent advances in the diagnosis and management of patients with membranous nephropathy similar to our practice population. We highlight the importance of establishing the idiopathic nature of this condition before initiating immunosuppressive therapy, which should include the screening for secondary causes, especially malignancy in the elderly population. The expected outcomes with and without treatment for patients with different risks of progression will be discussed to help guide clinicians in choosing the appropriate course of treatment. The role of conservative therapy as well as of established immunosuppressive treatment, such as the combination of cyclophosphamide and prednisone, and calcineurin inhibitors (CNIs), as well as of newer agents such as rituximab will be reviewed.

KEY MESSAGES

Appropriate assessment is required to exclude secondary conditions causing membranous glomerulonephritis. The role of antibodies to phospholipase A2 receptor (anti-PLA2R) in establishing the primary disease is growing, though more data are required. The increase in therapeutic options supports treatment individualization, taking into account the availability, benefits and risks, as well as patient preference.

FACTS FROM EAST AND WEST

(1) The prevalence of IMN is increasing worldwide, particularly in elderly patients, and has been reported in 20.0-36.8% of adult-onset NS cases. The presence of anti-PLA2R antibodies in serum or PLA2R on renal biopsy is the most predictive feature for the diagnosis of IMN and is used in both the East and West; however, appropriate screening to rule out secondary causes should still be performed. (2) Several observational (nonrandomized) Asian studies indicate a good response to corticosteroids alone in IMN patients, although no randomized controlled trials (RCTs) have been done in Asian membranous patients at high risk of progression. Corticosteroid monotherapy has failed in randomized controlled studies in Western countries and is therefore not recommended. (3) Cyclophosphamide is the most commonly prescribed alkylating agent in Europe and China. Also, chlorambucil is still used in some Western countries, particularly in Europe. In North America, CNIs are the more common first-line treatment. (4) Cyclosporine is predominantly used as monotherapy in North America, although KDIGO and Japanese guidelines still recommend a combination with low-dose corticosteroids. Clinical studies both in Asia and Europe showed no or little effects of monotherapy with mycophenolate mofetil compared to standard therapies. (5) There are encouraging data from nonrandomized Western studies for the use of rituximab and a few small studies using adrenocorticotropic hormone. Clinical trials are ongoing in North America to confirm these observations. These drugs are rarely used in Asia. (6) A Chinese study reported that 36% of IMN patients suffered from venous thromboembolism versus 7.3% in a North American study. Prophylactic anticoagulation therapy is usually added to IMN patients with a low risk of bleeding in both Eastern and Western countries. (7) The Chinese traditional medicine herb triptolide, which might have podocyte-protective properties, is used in China to treat IMN. An open-label, multicenter RCT showed that Shenqi, a mixture of 13 herbs, was superior to corticosteroids plus cyclophosphamide therapy to restore epidermal growth factor receptor in IMN patients, although proteinuria improvement was equal in the two groups. Importantly, Shenqi treatment induced no severe adverse events while standard therapy did.

An Overlapping Case of Lupus Nephritis and IgG4-Related Kidney Disease

We report a case of a 71-year-old Filipino female who was admitted to the hospital for abdominal pain, vomiting and diarrhea of 8 days duration. The patient was found to have marked acute kidney injury (AKI), which required hemodialysis in the next 3 days. Extensive workup revealed hematuria, subnephrotic range proteinuria, elevated anti-nuclear antibody (ANA) and elevated total immunoglobulin G (IgG) levels, with normal IgG4 and anti-dsDNA levels. On kidney biopsy, mild membranous glomerulonephritis was found, along with autoimmune tubulointerstitial nephritis (TIN) with a “full-house” pattern of immune deposits. These findings were suggestive of lupus interstitial nephritis. However, IgG4+ plasma cells were detected in the interstitium by immunostaining, favoring a diagnosis of IgG4-related kidney disease (IgG4-RKD). Our case highlights the difficulty in differentiating lupus nephritis (LN) from IgG4-RKD in some patients, raising the suspicion that these two entities can co-exist.

Recent advances in the understanding of immune-mediated nephrotic syndrome: diagnostic and prognostic implications

Glomerular diseases with severe defects in glomerular permeability give rise to heavy proteinuria and can present as nephrotic syndrome. There are many different causes of the nephrotic syndrome and a renal biopsy is nearly always needed to elucidate the underlying disease. During the last decade, substantial advances have occurred in the understanding of the pathophysiological mechanisms involved in immune-mediated glomerular diseases. Here, we review the diagnostic and prognostic implications of recent progress on the understanding of membranous nephropathy, minimal change disease, focal segmental glomerulosclerosis, amyloidosis, IgA nephropathy and membranoproliferative glomerulonephritis.

Lupus-like membranous nephropathy: Is it lupus or not?

BACKGROUND

Membranous glomerulonephritis is typically classified as idiopathic or secondary to systemic lupus erythematosus (SLE), hepatitis B, drugs, toxins, other infections, or malignancy. Not infrequently in some patients without a definite diagnosis of SLE, pathologic features of secondary membranous nephropathy are seen e.g., mesangial and/or subendothelial deposits, tubuloreticular inclusions, and full house immunofluorescence. In these patients, there is uncertainty about the etiology, response to therapy, and prognosis of membranous GN.

METHODS

We retrospectively reviewed the charts of 98 patients with membranous GN at San Francisco General Hospital and John Stroger Hospital of Cook County over a 10-year period. Data were collected and analyzed using SPSS.18.

RESULTS

Thirty-nine (40 %) had idiopathic membranous GN (Group 1), thirty-six (37 %) had lupus membranous GN (Group 2) and twenty-three (23 %) had some pathological features of secondary membranous GN, but no definite etiology of membranous GN (Group 3). At baseline (at time of renal biopsy) and after mean follow-up of 3.5 years, the average serum creatinine (in mg/dL) in Group 1 was (1.6 ± 1.0 versus 1.6 ± 1.7), Group 2 was (1.8 ± 2.5 versus 1.2 ± 0.9) and Group 3 was (1.1 ± 0.4 versus 1.27 ± 0.83), respectively. For the same time points, the average urine protein to creatinine ratio (g/g) in Group 1 was (9.8 ± 7.1 versus 5.7 ± 6.7), Group 2 was (4.2 ± 3.9 versus 1.7 ± 2.2), and Group 3 was (7.4 ± 5.7 versus 3.1 ± 3.8). In addition, during the follow-up period, eleven of 39 (28 %) in Group 1, two of 36 (6 %) in Group 2, and three of 23 (13 %) in Group 3 progressed to end-stage renal disease and were started on dialysis.

CONCLUSIONS

It appears that patients with lupus membranous GN have better renal prognosis than patients with idiopathic membranous GN. The renal prognosis for patients with pathological features of lupus membranous but no diagnosis of systemic lupus (lupus-like membranous GN) falls in between. Further studies are needed to determine if Group 3 patients can (a) definitively be classified as true idiopathic membranous GN or lupus membranous GN or (b) they have a separate disease from either M-type phospholipase A2 receptor membranous nephropathy or systemic lupus-induced membranous nephropathy.

Parasites alter the pathological phenotype of lupus nephritis

lpr

Lupus nephritis is one of the most serious complications of systemic lupus erythematosus and manifests with considerable phenotypic and histological heterogeneity. In particular, diffuse proliferative lupus nephritis (DPLN) and membranous lupus nephritis (MLN) represent morphologic forms that are polar opposites. DPLN is associated with autoimmune responses dominated by Th1 immune response associated with high levels of interferon (IFN)-γ. In contrast, a Th2 cytokine response is associated with the pathogenesis of MLN. MRL/lpr mice develop human LN-like immune complex-associated nephritis and provide a suitable histological model for human DPLN. Infection with Schistosoma mansoni skewed a Th2-type immune response induction and IL-10 in MRL/lpr mice, drastically changing the pathophysiology of glomerulonephritis from DPLN to MLN accompanied by increased IgG1 and IgE in the sera. T cells in 32-week-old MRL/lpr mice infected with S. mansoni expressed significantly more IL-4 and IL-10 than T cells of uninfected mice; T cells with IFN-γ were comparable between infected and uninfected MR/lpr mice. Thus, the helminthic infection modified the cytokine microenvironment and altered the pathological phenotype of autoimmune nephritis.

Glomerular diseases: membranous nephropathy--a modern view

Membranous nephropathy (MN) is an autoimmune disease usually associated with a nephrotic syndrome and it may progress to ESRD in the long term. Its etiology is often unknown (idiopathic MN), whereas other cases have a recognizable etiology (secondary MN). In idiopathic MN, the glomerular lesions are mainly caused by autoantibodies against a podocyte membrane protein, the M-type of phospholipase A2 receptor 1. The natural course of idiopathic MN is quite varied with spontaneous complete or partial remissions a relatively common occurrence. Patients with asymptomatic non-nephrotic proteinuria seldom progress and need only conservative management. Those with persistent full-blown nephrotic syndrome and those with declining renal function are candidates for specific treatment with any of several regimens. Cyclical therapy with alternating monthly intravenous and oral glucocorticoids combined with a cytotoxic agent can induce remission and preserve renal function in the long term. Cyclosporine or tacrolimus can induce remission, but relapses are frequent after the drug withdrawal. Mycophenolate mofetil monotherapy seems to be ineffective, but may be beneficial when administered together with steroids. The experience with adrenocorticotropic hormone, natural or synthetic, is limited to a few studies with short-term follow-up, but high rates of remission can be seen after prolonged treatment. A high rate of remission and good tolerance have also been reported with rituximab. Patients with moderate renal insufficiency may also benefit from treatment, but at a price of frequent and serious side effects. With these limitations in mind, idiopathic MN may be considered a treatable disease in many patients.

Kimura's disease associated with membranous nephropathy with IgG4 and phospholipase A2 receptor-positive staining of the glomerular basement membrane

Kimura's disease is a granulomatous disease of unknown origin that develops in the dermis, subcutaneous tissue and lymph nodes. Kimura's disease is frequently complicated by nephropathy, particularly membranous nephropathy (MN). It has recently been suggested that glomerular immunoglobulin (IgG)4 deposition may play a role in the pathogenesis of idiopathic MN. These IgG4 antibodies are thought to react with antigens, primarily the phospholipase A2 receptor (PLA2R) expressed on the podocyte cell membrane. We herein report a case of Kimura's disease with MN in which a renal biopsy specimen revealed positive staining for anti-IgG4 and anti-PLA2R antibodies.

Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy

BACKGROUND

Membranous glomerulopathy, though typically a disease of adults, does occur in children. Antiphospholipase A2 receptor (PLA2R) autoantibodies have recently been implicated as a causative agent in most cases of adult primary (idiopathic) membranous glomerulopathy. PLA2R staining of renal biopsies in two recent large case series of adults with primary membranous glomerulopathy showed a sensitivity of approximately 75 % for detecting primary membranous glomerulopathy. To our knowledge, this is the largest study of its kind to assess PLA2R staining in a pediatric population.

METHODS

Forty-one consecutive cases of pediatric membranous glomerulopathy were identified from our database, and clinical follow-up was performed to confirm primary membranous glomerulopathy. Twenty-two patients met inclusion criteria and are the subject of this report.

RESULTS

Granular, capillary loop immunofluorescence staining for immunoglobulin G (IgG) was present in 100 % of patients, and C3 staining was present in 77 %. PLA2R staining was identified in ten patients, providing a sensitivity of 45 % [confidence interval (CI) 25-67 %]. Bovine serum albumin staining was performed in all PLA2R-negative cases and showed no positivity. Morphologic findings associated with negative PLA2R staining included segmental membranous lesions, mesangial and subendothelial deposits, C1q and "full-house" staining, and lower-stage lesions by electron microscopy. At 38 months' average follow-up, all patients were still considered as having primary membranous glomerulopathy, with none developing a clinically detectable secondary etiology.

CONCLUSIONS

PLA2R staining sensitivity is much lower in the pediatric than the adult primary membranous glomerulopathy population. This finding suggests a more diverse and currently incompletely described set of etiologies for this disease in this group.

Diagnostic tests and treatment options in glomerular disease: 2014 update

Glomerular diseases historically have been challenging disorders to comprehend and treat for patients and physicians alike. Kidney biopsy is the gold standard of diagnosis, but the link between pathophysiology and the histologic representation of kidney injury has remained elusive in many of these diseases. As a result, treatment of glomerular disease usually involves therapies that are not specific to disease pathogenesis, such as blockade of the renin-angiotensin-aldosterone system and various immunosuppression regimens. Recent research has resulted in greater insight into some glomerular diseases, leading to the hope that new diagnostic tests and treatments targeting disease-specific mechanisms are on the horizon. We review recent progress on the understanding, diagnosis, and treatment of 4 glomerular diseases: immunoglobulin A nephropathy, focal segmental glomerulosclerosis, the C3 glomerulopathies, and idiopathic membranous nephropathy.

[Membranous nephropathy]

Membranous nephropathy is characterized by immune complex deposits on the outer side of the glomerular basement membrane. Activation of complement and of oxidation lead to basement membrane lesions. The most frequent form is idiopathic. At 5 and 10 years, renal survival is around 90 and 65% respectively. A prognostic model based on proteinuria, level and duration, progression of renal failure in a few months can refine prognosis. The urinary excretion of C5b-9, β2 and α1 microglobuline and IgG are strong predictors of outcome. Symptomatic treatment is based on anticoagulation in case of nephrotic syndrome, angiotensin conversion enzyme inhibitors, angiotensin II receptor blockers and statins. Immunosuppressive therapy should be discussed for patients having a high risk of progression. Corticoids alone has no indication. Treatment should include a simultaneous association or more often alternating corticoids and alkylant agent for a minimum of 6 months. Adrenocorticoid stimulating hormone and steroids plus mycophenolate mofetil may be equally effective. Steroids plus alkylant decrease the risk of end stage renal failure. Cyclosporine and tacrolimus decrease proteinuria but are associated with a high risk of recurrence at time of withdrawal and are nephrotoxic. Rituximab evaluated on open studies needs further evaluations to define its use.

The role of complement in membranous nephropathy

Membranous nephropathy (MN) describes a histopathologic pattern of injury marked by glomerular subepithelial immune deposits and collectively represents one of the most common causes of adult nephrotic syndrome. Studies in Heymann nephritis, an experimental model of MN, have established a paradigm in which these deposits locally activate complement to cause podocyte injury, culminating in cytoskeletal reorganization, loss of slit diaphragms, and proteinuria. There is much circumstantial evidence for a prominent role of complement in human MN because C3 and C5b-9 are found consistently within immune deposits. Secondary MN often shows the additional presence of C1q, implicating the classic pathway of complement activation. Primary MN, however, is IgG4-predominant and IgG4 is considered incapable of binding C1q and activating the complement pathway. Recent studies have identified the M-type phospholipase A2 receptor (PLA2R) as the major target antigen in primary MN. Early evidence hints that IgG4 anti-PLA2R autoantibodies can bind mannan-binding lectin and activate the lectin complement pathway. The identification of anti-PLA2R antibodies as likely participants in the pathogenesis of disease will allow focused investigation into the role of complement in MN. Definitive therapy for MN is immunosuppression, although future therapeutic agents that specifically target complement activation may represent an effective temporizing measure to forestall further glomerular injury.

Phospholipase A2 receptor (PLA2R) staining is useful in the determination of de novo versus recurrent membranous glomerulopathy

BACKGROUND

Membranous glomerulopathy (MG) is one of the most common glomerulonephritides involving the renal transplant. We sought to determine the utility of phospholipase A2 receptor (PLA2R) staining for the detection of recurrent MG. We also evaluated for increased evidence of antibody-mediated rejection in the de novo group, as some have reported.

METHODS

Twenty-two cases of MG occurring in renal transplant biopsies were identified, who had a tissue diagnosis documenting the primary native renal disease. There were 12 biopsies from 11 patients with recurrent MG and 12 biopsies from 11 patients with de novo MG. Morphologic evaluation and PLA2R staining was performed in all cases.

RESULTS

Ten of 12 (83%) recurrent MG and 1 of 12 (8%) de novo MG biopsies showed positive glomerular staining for PLA2R, giving PLA2R a sensitivity of 83% (95% confidence interval, 51%-97%) and specificity of 92% (95% confidence interval, 60%-100%) for recurrent MG. There were 2 of 12 (17%) de novo and 1 of 12 (8%) recurrent biopsies showing the presence of microcirculation inflammation. Peritubular capillary C4d staining was negative in all cases.

CONCLUSION

Recurrent MG is strongly correlated with PLA2R positivity, with a sensitivity of 83% and specificity of 92% for recurrent MG. There was no morphologic evidence of an association between antibody-mediated rejection and de novo MG, because both groups had a similar degree of microcirculation inflammation and peritubular capillary C4d staining. Most interestingly, PLA2R staining was almost always negative in de novo MG, suggesting a different mechanism in this unique form of MG.

Determination of primary versus secondary membranous glomerulopathy utilizing phospholipase A2 receptor staining in renal biopsies

Autoantibody formation directed against phospholipase A2 receptor (PLA2R)1 is the underlying etiology in most cases of primary membranous glomerulopathy. This new understanding of the pathogenesis of primary membranous is in the process of transforming the way the disease is diagnosed. We validated an indirect immunofluorescence assay to examine PLA2R1 in renal biopsies utilizing a commercially available antibody and standard indirect immunofluorescence. Using this assay, we examined a total of 165 cases of membranous glomerulopathy including 85 primary and 80 secondary. We found tissue staining for PLA2R1 to have a sensitivity of 75% (95% CI 65-84%) and a specificity of 83% (95% CI 72-90%) for primary membranous glomerulopathy. Hepatitis C virus was the secondary etiology with the most number of cases staining positive for PLA2R1 (7/11, 64%) followed by sarcoidosis (3/4, 75%) and neoplasm (3/12, 25%). Autoimmune etiologies showed rare PLA2R1-positive staining (1/46, 2%). All cases of secondary membranous glomerulopathy with positive PLA2R1 showed IgG4-predominant staining, which is typically associated with primary membranous glomerulopathy. This IgG4 predominance raises the possibility that these cases are more pathogenically related to primary membranous glomerulopathy than secondary. We present the largest case series to date examining PLA2R1 involvement in membranous glomerulopathy utilizing a technique that is readily adoptable by most renal pathology laboratories.

Secondary membranous nephropathy associated with guillain-barré syndrome

Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome (NS) in adults. It may be primary, usually mediated by IgG4 anti-phospholipase A2 autoantibodies or secondary to various other conditions. Guillain- Barré syndrome (GBS) has been associated with MN, but a cause and effect relation has not been proven. We present a case of concurrent development of GBS and severe NS, with renal biopsy demonstrating MN. IgG4 stain was negative, indicating that most likely, the MN was secondary and probably caused by the underlying GBS.

Idiopathic membranous nephropathy: clinical and histologic prognostic features and treatment patterns over time at a tertiary referral center

BACKGROUND

Idiopathic membranous nephropathy (i-MN) is a leading cause of nephrotic syndrome in adults and results in end-stage renal disease in approximately one third of patients. There are few large, long-term US studies evaluating clinical and histologic prognostic factors in i-MN.

METHODS

We describe 132 patients with biopsy-proven i-MN who were followed for a mean period of 68 months at our tertiary referral center from 1977 to 2009, and we analyzed clinical and histologic features that predicted renal outcomes.

RESULTS

The presence of hypertension and treating physician's decision to institute immunosuppression were negative predictors of attaining complete or partial remission. Among clinical variables, impaired renal function (eGFR <60 ml/min/1.73 m(2)) at time of presentation was the only variable at presentation associated with an increased risk of reaching end-stage renal disease. The use of statins and RAAS blockers were protective. The choice of corticosteroids as the initial immunosuppressive agent by referring physicians decreased over time but even in the most recent era (2000-2008) was significant (33%).

CONCLUSION

Renal function at presentation and non-white race were the main predictors of a worse renal outcome. Corticosteroid therapy is still being adopted as first-line therapy in a significant number of patients in this era. The development of guidelines may help clarify the treatment strategies of i-MN.

Accelerated recovery from nephrotic syndrome with acute renal failure by double filtration plasmapheresis in a patient with lupus podocytopathy

We describe a case of an adult female who presented with nephrotic syndrome. She was diagnosed with systemic lupus erythematosus with serum antinuclear antibodies, leucopenia with lymphopenia, butterfly erythema, and nephrotic syndrome. Renal biopsy revealed normal glomeruli with diffuse effacement of the foot processes, consistent with lupus podocytopathy. Although human albumin replacement was performed initially, acute renal failure developed rapidly. Therefore, she was treated with double filtration plasmapheresis (DFPP) in addition to oral steroid. After steroid therapy combined with DFPP, the renal function and proteinuria improved rapidly. Although the impact of DFPP on the treatment of lupus nephritis remains to be delineated, our observations suggest that DFPP in lupus podocytopathy played a pivotal role in facilitating the early recovery from renal injuries. Because of the rapid improvement of renal function without any change in body weight by DFPP, acute renal failure in the setting of lupus podocytopathy might contribute to an alternative pathophysiological factor for the diminished glomerular filtration rate, similar to that observed in the setting of idiopathic minimal change glomerulopathy.