Chronological change of renal pathological findings in the proliferative glomerulonephritis with monoclonal IgG deposits considered to have recurred early after kidney transplantation

Kidney Transplantation in Patients With Monoclonal Gammopathy of Renal Significance

Monoclonal gammopathy of renal significance (MGRS) defines disorders characterized by direct or indirect kidney injury caused by a monoclonal immunoglobulin produced by a B-cell or plasma-cell clone that does not meet current hematologic criteria for therapy. MGRS-associated kidney diseases are diverse and can result in the development of end-stage kidney disease. The current paradigm states that the underlying hematologic condition should be treated and in deep remission before kidney transplantation can be performed because recurrence has been reported for all MGRS-associated kidney diseases. However, we suggest that decisions regarding kidney transplantation in MGRS patients should be individualized considering many factors such as the subtype of MGRS-associated kidney disease, patient age and comorbidity, presence and risk of extrarenal complications, estimated waiting time, the availability of a living kidney donor, and previous hematological treatment and response. Thus, kidney transplantation should be considered even in treatment-naive patients, with hematological treatment initiated after successful kidney transplantation.

Progression of proliferative glomerulonephritis with monoclonal IgG deposits in pediatric patients

BACKGROUND

Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a glomerular disease defined by non-organized glomerular deposits of heavy and light chain-restricted immunoglobulin and is rarely reported in children.

METHODS

We characterized a series of nine pediatric patients from two academic centers with biopsy-proven PGNMID and additionally describe two patients with monotypic IgG in the setting of IgM deposition.

RESULTS

Each patient presented with hematuria and/or proteinuria; however, only five had elevated serum creatinine. Prodromal or concurrent infection was identified in six patients, low C3 in five, and alternate complement pathway gene variants in two. No monoclonal serum proteins were identified in five tested patients. Seven patients had monotypic deposits composed of IgG3-λ, two showed IgG3-κ, and one each IgG1 and IgG3 with lambda dominance in the setting of IgM deposition. The glomerular pattern was predominantly mesangial proliferative or membranoproliferative glomerulonephritis (MPGN). Treatment and outcomes were variable; four patients have recent PGNMID diagnoses and therefore minimal follow up, one had relatively stable kidney function for over a decade, and six experienced kidney failure, with four receiving transplants. Recurrent deposits of the same isotype were identified in five of six transplanted kidneys, corresponding to three of four transplanted patients. One of these patients developed PGNMID recurrences in three separate kidney allografts over a 20-year disease course.

CONCLUSIONS

Our study emphasizes the need for upfront IgG subclass investigation in pediatric mesangial or MPGN with IgG deposition and monotypic or biased light-chain staining. Furthermore, this pediatric experience suggests expanded pathogenic considerations in PGNMID. Graphical abstract.

Steroid-sensitive recurrent mesangial proliferative glomerulonephritis with monoclonal IgG deposits

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) is a rare kidney disease. The predominant pathological finding of PGNMID is the presence of monoclonal Ig deposits on the glomerular basement membrane (GBM). However, there is some variation in deposition pattern in this kidney disease. We report a case of steroid-sensitive recurrent mesangial proliferative type of PGNMID. A 40-year-old female noticed lower leg pitting edema and polyuria. Approximately 10 days prior to the first clinic visit, she was diagnosed with nephrotic syndrome based on the laboratory data of urine and blood. Immunological and hematological examination revealed no abnormality. However, kidney biopsy specimens showed mild mesangial cell proliferation and mesangial matrix accumulation on light microscopic findings. Regarding immunofluorescence staining, granular deposits of IgG, C1q, and β1c were observed on GBM and mesangial area. Granular deposits of IgG3 and λ were also observed on GBM and mesangial area. Moreover, negative results were obtained for the phospholipase A2 receptor antibody and thrombospondin type-1 domain-containing 7A. Electron microscopy revealed highly electron dense deposits mainly in the mesangial region. Kidney biopsy showed mesangial proliferative glomerulonephritis characterized by monoclonal Ig deposition of IgG3/λ. Steroid therapy was initiated, and complete remission was achieved on day 36. After the discontinuation of steroid therapy, proteinuria recurred and second kidney biopsy findings were almost similar to the first biopsy. However, complete remission was achieved with steroid therapy. This is a rare recurrent case of steroid-sensitive PGNMID. The pathological feature of this case was mesangial proliferative glomerulonephritis with Ig deposition of IgG3/λ.

An update to the pathogenesis for monoclonal gammopathy of renal significance

Monoclonal gammopathy of renal significance (MGRS) is characterized by the nephrotoxic monoclonal immunoglobulin (MIg) secreted by an otherwise asymptomatic or indolent B-cell or plasma cell clone, without hematologic criteria for treatment. The spectrum of MGRS-associated disorders is wide, including non-organized deposits or inclusions such as C3 glomerulopathy with monoclonal glomerulopathy (MIg-C3G), monoclonal immunoglobulin deposition disease, proliferative glomerulonephritis with monoclonal immunoglobulin deposits and organized deposits like immunoglobulin related amyloidosis, type I and type II cryoglobulinaemic glomerulonephritis, light chain proximal tubulopathy, and so on. Kidney biopsy should be conducted to identify the exact disease associated with MGRS. These MGRS-associated diseases can involve one or more renal compartments, including glomeruli, tubules and vessels. Hydrophobic residues replacement, N-glycosylated, increase in isoelectric point in MIg causes it to transform from soluble form to tissue deposition, causing glomerular damage. Complement deposition is found in MIg-C3G, which is caused by an abnormality of the alternative pathway and may involve multiple factors including complement component 3 nephritic factor, anti-complement factor auto-antibodies or MIg which directly cleaves C3. The effect of transforming growth factor beta and platelet-derived growth factor-β on mesangial extracellular matrix is associated with glomerular and tubular basement membrane thickening, nodular glomerulosclerosis, and interstitial fibrosis. Furthermore, inflammatory factors, growth factors and virus infection may play an important role in the development of the diseases. In this review, for the first time, we discussed current highlights in the mechanism of MGRS-related lesions.

An update to the pathogenesis for monoclonal gammopathy of renal significance

Monoclonal gammopathy of renal significance (MGRS) is characterized by the nephrotoxic monoclonal immunoglobulin secreted by an otherwise asymptomatic or indolent B cell or plasma cell clone, without hematologic criteria for treatment. These MGRS-associated diseases can involve one or more renal compartments, including glomeruli, tubules, and vessels. Hydrophobic residue replacement, N-glycosylated, increase in isoelectric point in monoclonal immunoglobulin (MIg) causes it to transform from soluble form to tissue deposition, and consequently resulting in glomerular damage. In addition to MIg deposition, complement deposition is also found in C3 glomerulopathy with monoclonal glomerulopathy, which is caused by an abnormality of the alternative pathway and may involve multiple factors including complement component 3 nephritic factor, anti-complement factor auto-antibodies, or MIg which directly cleaves C3. Furthermore, inflammatory factors, growth factors, and virus infection may also participate in the development of the diseases. In this review, for the first time, we discussed current highlights in the mechanism of MGRS-related lesions.