IgG4-Related Membranous Nephropathy After COVID-19 Vaccination: A Case Report

Although immunoglobulin G4 (IgG4)-related kidney diseases are typically characterized by tubulointerstitial nephritis with abundant infiltration of IgG4-positive plasma cells and fibrosis, there have been relatively rare cases of IgG4-related glomerulonephritis. Several cases of IgG4-related disease (IgG4-RD) following coronavirus disease 2019 (COVID-19) mRNA vaccination have been reported. However, there are no reports of IgG4-related glomerulonephritis following COVID-19 vaccination. Herein, we present a case of IgG4-related membranous nephropathy (MN) occurring after COVID-19 vaccination. A 69-year-old Japanese male presented to our hospital with edema that started the day after his second COVID-19 vaccination. The patient exhibited nephrotic syndrome and was diagnosed with MN based on the results of a kidney biopsy. Although serum IgG4 levels were elevated to 946 mg/dL, no evidence of organ involvement suggestive of IgG4-RD was observed. Treatment with prednisolone and cyclosporine resulted in complete remission, and immunosuppressive agents were tapered. However, one month after discontinuing the immunosuppressive agents, the patient was readmitted with swelling around the submandibular glands and exertional dyspnea. Serum IgG4 level was markedly elevated at 2,320 mg/dL, and computed tomography revealed submandibular gland swelling and thickening of the interlobular septum and bronchovascular bundles in both lungs. The patient was diagnosed with IgG4-RD based on elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells in the submandibular gland biopsy. Upon resuming treatment with prednisolone, the symptoms attributed to IgG4-RD improved within a few days. In cases of nephrotic syndrome following COVID-19 vaccination, it may be advisable to conduct detailed examinations to assess the possibility of the development of IgG4-RDs.

MicroRNA193a: An Emerging Mediator of Glomerular Diseases

MicroRNAs (miRNAs) are noncoding small RNAs that regulate the protein expression of coding messenger RNAs. They are used as biomarkers to aid in diagnosing, prognosticating, and surveillance of diseases, especially solid cancers. MiR-193a was shown to be directly pathogenic in an experimental mouse model of focal segmental glomerulosclerosis (FSGS) during the last decade. Its specific binding and downregulation of Wilm's tumor-1 (WT-1), a transcription factor regulating podocyte phenotype, is documented. Also, miR-193a is a regulator switch causing the transdifferentiation of glomerular parietal epithelial cells to a podocyte phenotype in in vitro study. Interaction between miR-193a and apolipoprotein 1 (APOL1) mRNA in glomeruli (filtration units of kidneys) is potentially involved in the pathogenesis of common glomerular diseases. Since the last decade, there has been an increasing interest in the role of miR-193a in glomerular diseases, including diabetic nephropathy and membranous nephropathy, besides FSGS. Considering the lack of biomarkers to manage FSGS and diabetic nephropathy clinically, it is worthwhile to invest in evaluating miR-193a in the pathogenesis of these diseases. What causes the upregulation of miR-193a in FSGS and how the mechanism is different in different glomerular disorders still need to be elucidated. This narrative review highlights the pathogenic mechanisms of miR-193a elevation in various glomerular diseases and its potential use in clinical management.

Tetrandrine may treat membranous glomerulopathy via P13K/Akt signaling pathway regulation: therapeutic mechanism validation using Heymann nephritis rat model

Membranous glomerulopathy (MGN) is an autoimmune kidney disease that is the primary cause of nephrotic syndrome (NS) in adults. Tetrandrine, a bisbenzylisoquinoline alkaloid, is known to have numerous pharmacological effects. In this study, network pharmacology analysis and experimental validation were conducted to analyze the mechanisms by which tetrandrine functions as a therapeutic intervention for MGN. A systematic network pharmacology method was applied to identify potential targets and determine the therapeutic mechanism of tetrandrine in MGN treatment. A Heymann nephritis (HN) rat model was developed to assess the therapeutic effects of tetrandrine on NS and validate the predicted molecular mechanisms. We obtained 86 potential targets of tetrandrine for the treatment of NS. In vivo experiments showed that tetrandrine could reduce the 24-h urine protein content, decrease glomerular basement membrane proliferation, and significantly decrease thylakoid stroma and cell proliferation in the HN rat kidney tissue. Moreover, tetrandrine suppressed kidney cell apoptosis and upregulated the expression of nephrin and podocin in HN model rats. qRT-PCR results revealed that tetrandrine inhibited IL-1β, TNFα, and MCP-1 levels in HN model rats. Western blot results indicated that tetrandrine can protect against MGN via the PI3K/Akt signaling pathway. Thus, by using a combination of network and experimental pharmacology methods, we demonstrate that tetrandrine can treat MGN via the PI3K/Akt signaling pathway and provide novel insights into the mechanisms underlying tetrandrine-mediated management of MGN.

Epidemiology and Pathophysiology of Glomerular C4d Staining in Native Kidney Biopsies

Introduction

Routine C4d staining in renal transplantation has stimulated its use in kidney biopsies with glomerulonephritis (GN). Methodical description on staining patterns in the native kidney is not available.

Methods

We retrospectively evaluated C4d staining in formalin-fixed paraffin-embedded sections from 519 native kidney biopsies (bx) with and without glomerular disease.

Results

Strong C4d staining was consistently present in immune-complex GN, including lupus nephritis (LN) (n = 68), membranous GN (n = 24), membranoproliferative glomerulonephritis (MPGN) pattern (n = 22), fibrillary GN (n = 3), and proliferative GN with monoclonal IgG (n = 3). C4d stained all cases of postinfectious GN (n = 7) amyloidosis (n = 20) and C1q GN (n = 3). In contrast, IgA nephropathy (IgAN) (n = 34), was negative in 62% of bx, with the rest staining variably. The E1 Oxford classification score correlated with capillary wall C4d staining (P = 0.05). C4d marked the glomerular and arteriolar lesions in thrombotic microangiopathy (TMA; n = 16), the glomerular sclerotic segments in focal segmental glomerulosclerosis (FSGS; n = 77), and marked areas of necrosis in crescentic GN (n = 21). In diabetic glomerulopathy (n = 70), C4d marked advanced insudative lesions but was negative otherwise. C4d weakly stained the mesangium, or was negative in normal biopsies (n = 13), minimal change disease (MCD; n = 21), thin basement membrane disease (n = 20), Alport (n = 3), IgM nephropathy (n = 2), C3 glomerulopathy (n = 5), acute interstitial nephritis (n = 12), acute tubular necrosis (n = 22), ischemic glomerulopathy/nephrosclerosis (n = 23), and other miscellaneous processes (n = 14). Staining in tubular basement membranes and peritubular capillaries was most common in lupus.

Conclusion

Based on reliable staining in lupus and membranous GN, C4d staining is potentially useful as a screening and diagnostic tool, if only paraffin-embedded tissue is available. Knowledge of C4d staining patterns in normal and pathological tissues enhances its diagnostic value.

Membranous Glomerulopathy With Light Chain-Restricted Deposits: A Clinicopathological Analysis of 28 Cases

Introduction

Membranous glomerulopathy (MG) is a common cause of nephrotic syndrome that results from the formation of immune complexes along the subepithelial aspect of the glomerular basement membranes. Although it is most frequently caused by polytypic deposits, cases with light chain isotype-restricted deposits are rarely seen.

Methods

We conducted a retrospective analysis of 28 cases of MG that showed light chain isotype restriction.

Results

The mean age at diagnosis was 62.2 years and the male-to-female ratio was 1. All patients presented with proteinuria (73.1% nephrotic range), and the mean serum creatinine was 1.5 mg/dl. Six patients had an underlying lymphoproliferative disorder (LPD), 2 had autoimmune disease, and 1 patient was positive for both hepatitis B and syphilis. Only 1 of the patients with an LPD had a detectable monoclonal Ig. Four patients (14.3%) showed focal proliferation or crescents, 3 of whom had an underlying LPD. Kappa (κ) restriction was seen in 26 of 28 patients (85.7%). Staining for IgG subclasses was performed in 19 cases, 14 of which showed positive staining for a single subclass. PLA2R was positive in 7 of 27 cases. 30% of PLA2R-negative patients and 28.6% of those with positive staining for a single IgG subclass had an associated LPD.

Discussion

The majority of MG cases with light chain isotype-restricted deposits lack a recognizable secondary etiology. However, the absence of PLA2R positivity, positive staining for a single IgG subclass, and presence of focal proliferation are worrisome histopathologic features that should prompt a thorough clinical workup to exclude the presence of an underlying LPD.

A case of membranous glomerulopathy associated with lung cancer and review of the literature

Membraneous nephropathy (MN) is the most commonly occurring nephrotic syndrome in adults as well as the most common paraneoplastic nephropathy associated with solid tumors, and it is mostly associated with gastrointestinal system and lung carcinomas. Accurate diagnosis is important as the treatment of paraneoplastic glomerulonephritis is very varied from that of idiopathic ones. In the current report, a case of a patient that was referred with proteinuria and edema and was diagnosed with lung cancer, and responded markedly to treatment of malignancy, with improvement of MN, is presented. Active cancer is present in all patients with paraneoplastic MN. In numerous patients, the paraneoplastic MN and cancer diagnoses are made within one year of each other. The treatment of paraneoplastic syndromes is usually associated with the treatment of primary malignancy. There are conflicting data on which treatment modality is more suitable. In conclusion, further studies are required in order to determine the actual incidence of cancer in patients with nephropathy, explain the physiopathological association between cancer and nephropathy and to determine the most suitable treatment approaches.

Safety and Efficacy of Combination ACTHar Gel and Tacrolimus in Treatment-Resistant Focal Segmental Glomerulosclerosis and Membranous Glomerulopathy

Introduction

H.P. ACTHar gel is a preparation of melanocortin peptides that has been used to treat resistant forms of nephrotic syndrome. To determine whether combination therapy with ACTHar gel and tacrolimus reduces proteinuria and stabilizes renal function, we conducted a prospective, open-label trial in patients with treatment-resistant membranous glomerulopathy (MGN) and focal segmental glomerulosclerosis (FSGS).

Methods

Nine patients with treatment-resistant MGN and 13 with treatment-resistant FSGS received subcutaneous ACTHar gel for 6 months. Patients with no response or a partial response to ACTHar gel alone received an additional 6 months of therapy with combination ACTHar gel and oral tacrolimus. The study endpoint was the percentage of patients achieving a complete or partial remission after 6 months of combination therapy.

Results

Among patients with MGN, treatment with ACTHar gel alone achieved a partial remission in 44% and no response in 56% of patients. No patient achieved a complete response with ACTHar gel therapy alone. An additional 6 months of combination therapy with ACTHar gel and tacrolimus resulted in partial and complete response rates of 25% and 75%, respectively. Among patients with FSGS, ACTHar gel therapy alone resulted in complete and partial response rate of 7.7% and 62.0%. Combination therapy increased complete response rates to 17% and partial responses to 66%. Proteinuria (urinary protein-to-creatinine ratio) was significantly reduced in both patients with MGN and those with FSGS after 6 months of ACTHar gel alone and was further reduced among the patients with MGN with the addition of tacrolimus. There were no significant changes in estimated glomerular filtration rate during the treatment phase or long-term follow-up.

Discussion

Combination therapy with ACTHar gel and tacrolimus was well tolerated by patients with treatment-resistant MGN and FSGS and significantly reduced proteinuria and improved clinical response rates compared with ACTHar gel alone.

Autoimmune Thyroiditis and Glomerulopathies

Autoimmune thyroiditis (AIT) is generally associated with hypothyroidism. It affects ~2% of the female population and 0.2% of the male population. The evidence of thyroid function- and thyroid autoantibody-unrelated microproteinuria in almost half of patients with AIT and sometimes heavy proteinuria as in the nephrotic syndrome point to a link of AIT with renal disease. The most common renal diseases observed in AIT are membranous nephropathy, membranoproliferative glomerulonephritis, minimal change disease, IgA nephropathy, focal segmental glomerulosclerosis, antineutrophil cytoplasmic autoantibody (ANCA) vasculitis, and amyloidosis. Different hypotheses have been put forward regarding the relationship between AIT and glomerulopathies, and several potential mechanisms for this association have been considered. Glomerular deposition of immunocomplexes of thyroglobulin and autoantibodies as well as the impaired immune tolerance for megalin (a thyrotropin-regulated glycoprotein expressed on thyroid cells) are the most probable mechanisms. Cross-reactivity between antigens in the setting of genetic predisposition has been considered as a potential mechanism that links the described association between ANCA vasculitis and AIT.

Clinicopathologic Features of Membranous-Like Glomerulopathy With Masked IgG Kappa Deposits

Introduction

Ig deposits identified on renal biopsy samples by paraffin immunofluorescence that show negative staining by routine immunofluorescence on frozen tissue have become known as “masked” deposits. Membranous-like glomerulopathy with masked IgG kappa (κ) deposits is a recently recognized pattern of immune complex deposition characterized by masked deposits that show IgG κ restriction and are subepithelial and mesangial by electron microscopy. Based on the frequent presence of C3-only staining by routine immunofluorescence microscopy (IF), these cases could be misdiagnosed as C3 glomerulonephritis in the absence of paraffin immunofluorescence evaluation.

Methods

The clinicopathologic details of all cases of membranous-like glomerulopathy with masked IgG κ deposits diagnosed in our laboratory were included, beginning with the initial recognition of this entity in 2011 through the end of 2015. Inclusion was based on renal biopsy sample morphologic features including glomerular deposits that stain for IgG κ and have a staining intensity that is significantly brighter by paraffin IF than by routine IF on frozen tissue.

Results

This pattern of immune complex deposition has been seen in 41 patients in our laboratory over a 5-year period. The patients with these biopsy findings are most commonly young female individuals with a mean age of 27.5 years, with 88% being less than 40 years. All patients had proteinuria with a mean 24-hour urine protein of 3.5 g (range 0.5−12.8 years) and 35% with nephrotic-range proteinuria. Hematuria was present in 88% of patients, and 29% had elevated serum creatinine at presentation. Autoimmune serologic tests were positive in 55% of patients, with a weakly positive antinuclear antibody being most common. Despite this, only 1 patient (2%) fulfilled the diagnostic criteria for systemic lupus erythematosus. The outcome data were mixed, as some patients showed spontaneous remission and mild disease whereas others progressed to end-stage renal disease. There was no apparent correlation between the treatment used and outcome in this retrospective analysis. One patient underwent transplantation and developed biopsy-proven recurrence of disease in the graft 42 months posttransplantation. The etiology of this entity remains unknown.

Discussion

We provide an expanded case series detailing the clinicopathologic findings of patients with membranous-like glomerulopathy with masked IgG κ deposits. Patients are most commonly young female individuals <40 years of age and commonly have positive autoimmune serologic studies such as antinuclear antibody, although few carry a diagnosis of any well-defined autoimmune disease such as lupus. The outcome data were mixed, as some patients showed spontaneous remission and mild disease whereas others progressed to ESRD. There was no apparent correlation between the treatment used and outcome in this retrospective analysis.

Membranous nephropathy with crescents: a series of 19 cases

BACKGROUND

Membranous nephropathy (MN) with crescents is rare and, in the absence of lupus, usually is associated with anti-glomerular basement membrane (anti-GBM) nephritis or antineutrophil cytoplasmic antibody (ANCA)-positive glomerulonephritis. Only rare cases of crescentic MN without ANCA or anti-GBM have been reported.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

19 patients with ANCA- and anti-GBM-negative crescentic MN and no clinical evidence of systemic lupus.

OUTCOMES

Clinical features, kidney biopsy findings, laboratory results, treatment, and follow-up of patients with crescentic MN.

RESULTS

Mean age was 55 (range, 5-86) years. All patients presented with proteinuria (mean protein excretion, 11.5 [range, 3.3-29] g/d) and nearly all had hematuria; 16 of 19 (84%) patients had decreased estimated glomerular filtration rates (eGFRs; mean serum creatinine, 2.9 [range, 0.4-10] mg/dL; mean eGFR, 39.7 [range, 4 to >100] mL/min/1.73 m2). Glomeruli showed on average 25% (range, 2%-73%) involvement by crescents. All showed a membranous pattern; 7 showed mesangial and 2 showed segmental endocapillary proliferation. By immunofluorescence, all cases showed granular subepithelial immunoglobulin G (IgG) and κ and λ light chains, and all but one showed C3; 5 showed C1q or IgA. Electron microscopy revealed stages I-III MN; 38% of cases were M-type phospholipase A2 receptor (PLA2R) associated, indicating that at least some were primary MN. Follow-up clinical data were available for all patients (mean, 22 [range, 1.5-138] months). 14 patients received immunosuppressive therapy, and 2, only angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy. 4 patients (21%) progressed to end-stage renal disease, at 0-9 months postbiopsy. Mean serum creatinine level of those without end-stage renal disease at follow-up was 1.7 (range, 0.5-4.1) mg/dL; mean eGFR was 53.3 (range, 16-103) mL/min/1.73 m2. 67% of patients had proteinuria with protein excretion≥1 (mean, 3.2) g/d at follow-up.

LIMITATIONS

Retrospective study.

CONCLUSIONS

Crescentic MN is a rare variant of MN that usually presents with heavy proteinuria, hematuria, and decline in GFR. The prognosis is variable and the disease may respond to therapy, but most patients develop a long-term decline in GFR.

Membranous glomerulopathy and treatment with Acthar®: a case study

Treatment options for refractory membranous nephropathy are limited. Herein we describe the case of a 46-year-old white male with membranous nephropathy who progressed during 3 years of treatment with antihypertensive agents (specifically angiotensin-converting enzyme inhibitors and angiotensin receptor blockers), diuretics, simvastatin, prednisone, cyclosporine A, and mycophenolate mofetil. Prior to initiation of treatment with H.P. Acthar® Gel, his proteinuria level was 9,520 mg/dL (952.0 g/L) but it decreased to 2,948 mg/dL (294.8 g/L) after 10 months of Acthar therapy. After 13 months, treatment with Acthar was halted as his 24-hour urinary protein was 1,628 mg/dL (162.8 g/L); by 15 months, it was 407 mg/dL (40.7 g/L). The patient has remained free of signs and symptoms of membranous nephropathy for 1.5 years. These results support the use of Acthar as an effective and safe therapy for patients with refractory membranous nephropathy.

Membranous glomerulopathy with superimposed pauci-immune necrotizing crescentic glomerulonephritis

We describe a 61-year-old woman with acute kidney injury, nephrotic range proteinuria and hematuria. Kidney biopsy showed membranous glomerulopathy (MG) with superimposed pauci-immune necrotizing crescentic glomerulonephritis (PNCGN). Coexistent MG and PNCGN is a rare occurrence. The diagnosis of such an exceptionally rare combination relies on the combination of renal biopsy findings and serologic testing. We also review previous reported cases and discuss possible pathogenesis of this rare dual glomerulopathy.

Membranous glomerulopathy in an adult patient with X-linked agammaglobulinemia receiving intravenous gammaglobulin

BACKGROUND

Immune complex deposition in the subepithelial zone of glomerular capillaries can lead to membranous glomerulopathy.

OBJECTIVE

To present the case of a 23-year-old man with X-linked agammaglobulinemia (XLA) who developed idiopathic membranous glomerulopathy while receiving intravenous immunoglobulin (IVIG).

METHODS

We performed an immunological workup, genetic testing, and a renal biopsy.

RESULTS

XLA was confirmed with less than 0.02% CD19+ cells in the blood after sequence analysis revealed a nonfunctional BTK gene. The patient presented with microhematuria, which persisted for 3 years and spanned treatment with 5 different preparations of intravenous gammaglobulin. Immunohistochemistry revealed membranous glomerulopathy.

CONCLUSION

Although endogenous serum immunoglobulin (Ig) production is severely impaired in XLA, rare B lymphocytes that have managed to mature can produce functional IgG antibodies. The pathogenic immune complexes could reflect IVIG reacting with polymorphic autoantigens, an endogenous IgG-producing clone reacting with a common idiotype present in the IVIG, or both.

Membranous nephropathy in children: clinical presentation and therapeutic approach

The approach to the pediatric patient with membranous nephropathy (MN) can be challenging to the practitioner. The clinical presentation of the child with this histologic entity usually involves some degree of proteinuria ranging from persistent, subnephrotic-ranged proteinuria to overt nephrotic syndrome. Patients often have accompanying microscopic hematuria and may have azotemia or mild hypertension. Children presenting with nephrotic syndrome are often steroid resistant; as such, their biopsy for steroid-resistant nephrotic syndrome results in the diagnosis of MN. The practitioner treating MN in the pediatric patient must weigh the risks of immunosuppressive therapy against the benefits. In general, the child with subnephrotic proteinuria and normal renal function can likely be treated conservatively with angiotensin blockade (angiotensin-converting enzyme inhibitors or angiotensin receptor blockers) without the need for immunosuppressive therapy. Those with nephrotic syndrome are usually treated with steroids initially and often followed by alkylating agents (cyclophosphamide or chlorambucil). Calcineurin inhibitors may also be useful, but the relapse rate after their discontinuation remains high. The absence of controlled studies in children with MN makes treatment recommendations difficult, but until they are available, using the patient's clinical presentation and risk of disease progression appears to be the most prudent approach.

MPO-ANCA crescentic glomerulonephritis complicated by membranous nephropathy: MPO demonstrated in epimembranous deposits

An elderly woman presented with haematuria and proteinuria accompanied by elevated serum myeloperoxidase (MPO)-specific anti-neutrophil cytoplasmic antibodies (MPO-ANCA). A renal biopsy revealed mild mesangial proliferation with fibrocellular crescent formation and a membranous glomerular lesion. Immunofluorescence microscopy using FITC-labelled rabbit anti-human MPO antibodies revealed granular MPO deposition along the glomerular capillary walls (GCW) with a staining profile similar to that of glomerular IgG deposition. The one-year follow-up renal biopsy revealed minimal IgG and undetectable MPO deposition. Both MPO and MPO-ANCA might have been responsible for the IgG immune depositions along the GCW in this patient.