Light-chain proximal tubulopathy: a retrospective study from a single Chinese nephrology referral center.

Background: Light-chain proximal tubulopathy (LCPT) is a rare disease characterized by the accumulation of monoclonal light chains within proximal tubular cells. This study aimed to investigate the clinical characteristics of LCPT from a single Chinese nephrology referral center.Methods: Patients with kidney biopsy-proven isolated LCPT between 2016 and 2022 at Peking University First Hospital were retrospectively included. Clinical data, kidney pathological type, treatment, and prognosis were analyzed.Results: Nineteen patients were enrolled, the mean age at diagnosis was 57 ± 11 and the sex ratio was 6/13 (female/male). Mean proteinuria was 2.44 ± 1.89 g/24 hr and the mean estimated glomerular filtration rate (eGFR) at the point of biopsy was 59.640 ± 27.449 ml/min/1.73 m2. κ-restriction (84%) was dominant among LCPTs. An abnormal free light chain ratio was observed in 86% of the patients. Proximal tubulopathy with cytoplasmic inclusions accounted for the majority (53%), followed by tubulopathy associated with interstitial inflammation reaction (26%), proximal tubulopathy without cytoplasmic inclusions (16%), and proximal tubulopathy with lysosomal indigestion/constipation (5%). One patient presented with acute kidney injury and 16 patients presented with chronic kidney disease. Regarding follow-up, patients received bortezomib-based or R-CHOP chemotherapy or supportive treatment only. The mean follow-up time was 22 ± 16 months, and the mean eGFR was 63.098 ± 27.439 ml/min/1.73 m2 at the end of follow-up. These patients showed improved or stable kidney function.Conclusions: This is the first case series report of LCPT in four different pathological types in northern China. Clone-targeted chemotherapy may help preserve the kidney function in these patients.

Primary membranous nephropathy in two siblings with one combined with anti-glomerular basement membrane disease: a case report.

BACKGROUND: The phospholipase A2 receptor (PLA2R) associated with membranous nephropathy (MN) is an organ-specific autoimmune disease associated with PLA2R and human leukocyte antigen (HLA) genes. Familial PLA2R-related MN is rarely reported. The combination of anti-GBM disease and MN has been well documented, though the mechanism behind it remains unclear. CASE PRESENTATION: We describe two siblings diagnosed with pathology-confirmed PLA2R-related MN 1 year apart. And one of the two siblings developed an anti-GBM disease. The high-resolution HLA typing showed identical alleles in both siblings, specifically heterozygotes of DRB1*15:01/*03:01. CONCLUSION: We describe a familial case of PLA2R-related MN supporting the role of genetic factors that HLA-DRB1*15:01 and DRB1*03:01 predispose patients in the development of PLA2R-related MN in the Han Chinese population. The combination of MN and anti-GBM disease may also partially be associated with the same susceptible HLA allele DRB1*15:01.

Myeloma cast nephropathy with diffuse amyloid casts without systemic amyloidosis: two cases report.

BACKGROUND: Multiple myeloma (MM) is a plasma-cell derived hematologic malignant disease. The malignant proliferating plasma cells secrete massive monoclonal immunoglobulins which lead to various pathologic types of renal injury. Myeloma cast nephropathy (MCN) is the most common histopathologic lesion with the worst renal prognosis. Rarely, the free light chains in the protein casts can form amyloid fibrils. Here, we reported two rare cases of MCN with diffuse amyloid casts. CASE PRESENTATION: Case 1: A 54-year-old Chinese man presented with a 4-year history of multiple myeloma, proteinuria and hematuria. He had monoclonal IgAλ plus free λ spike in both serum and urine. He had been on chemotherapy for 4 years and maintained normal serum creatinine until 11 months ago. Then, his renal function deteriorated and he went on hemodialysis 4 months before admission. Renal biopsy showed diffuse amyloid casts in the tubular lumens, without any obvious amyloid deposits in other kidney compartments or signs of extra-renal amyloidosis. The amyloid fibrils formed around mononuclear cells which were CD68 negative. According to the morphology and location, these mononuclear cells were considered as tubular epithelial cells. The patient was maintained on chemotherapy and hemodialysis. He died 8 months after renal biopsy. Case 2: A 58-year-old Chinese man presented with a one-and-a-half-year history of proteinuria and slowly rising serum creatinine. He had monoclonal IgDλ spike in both serum and urine. Amyloid casts were observed in the tubular lumens and mononuclear cells could be identified in the center of some casts. There were no amyloid deposits in other kidney compartments and no sign of systemic amyloidosis. The patient also had fine granular deposits along the tubular basement membrane with λ linear staining along tubular basement membrane suggesting light chain deposition disease. He was treated with bortezomib-based chemotherapy followed by lenalidomide-based chemotherapy and achieved very good partial remission (VGPR). After 27 months of follow-up, the patient still showed no signs of systemic amyloidosis. CONCLUSIONS: These 2 cases of MCN with diffuse amyloid casts have different histopathologic characteristics from the usual myeloma casts and tubular epithelial cells might play important roles in the pathogenesis.

C3 glomerulonephritis associated with monoclonal gammopathy: a retrospective case series study from a single institute in China.

OBJECTIVE: To investigate the demographic and clinicopathological features and renal outcomes of Chinese patients with C3 glomerulonephritis in the setting of monoclonal gammopathy. METHODS: Patients with renal biopsy-proven C3 glomerulonephritis and detectable serum and/or urine monoclonal immunoglobulin from 2006 to 2018 in Peking University First Hospital were included, their clinical data, renal pathology type, treatment, and prognosis were collected and analyzed. RESULTS: Nineteen patients were enrolled, accounting for 24% of C3GN patients in the study period. The mean age of onset was 55 years old and the gender ratio was 4/15 (female/male). The mean eGFR at biopsy was 49.55 ± 29.81 ml/min/1.73m2. The prominent clinical manifestations included nephrotic syndrome (58%), anemia (68%), microscopic hematuria and leukocyturia (58%), and hypocomplementemia (13, 68%). The IgG was the most common isotype of monoclonal Ig on immunofixation electrophoresis. Kidney biopsies revealed a relatively prominent MPGN pattern. Only two patients had direct evidence of monocle immunoglobulins acting as C3GN pathogenic factors. Two patients had concurrent TMA-like renal injuries. The median renal survival was 12 and 15 months, respectively in patients receiving conservative therapy and immunosuppressant therapy, without statistical significance. The efficacy of clone-targeted therapy needed further investigation. Plasma exchange therapy only improved one patient's renal outcome. CONCLUSIONS: This is the first case series report of C3GN combined with monoclonal Ig in northern China. The renal prognosis of these patients is poor, and immunosuppressant therapies show no advantage over supportive therapy in renal prognosis, while the benefit of clone-targeted chemotherapy is still requiring investigation.

Population pharmacokinetics of cyclosporine A in Chinese patients with nephrotic syndrome in individualized drug administration
.

OBJECTIVE: To establish a population pharmacokinetic (PopPK) model of cyclosporine A (CsA) in Chinese patients with nephrotic syndrome (NS) and to use the model to guide the adjustment of individualized dosage regimens. MATERIALS AND METHODS: 216 CsA therapeutic drug monitoring (TDM) concentration observations were collected from 127 Chinese patients with NS. The basic model was developed as a one-compartment PK model with first-order absorption and linear elimination. The first-order conditional estimation (FOCE) method was applied to establish the final model with covariates using NONMEM software. The final model was evaluated through internal validation including goodness-of-fit analysis and bootstrap method as well as external validation using 39 additional PK observations from 35 patients with NS. RESULTS: A PopPK model of CsA was established in Chinese NS patients with influence of body weight on clearance. The internal and external validation results showed that the final model was stable. CONCLUSION: The established population model adequately characterized the PK of CsA in Chinese patients and could support individualized medication during treatment of NS with CsA.

Renal pathologic spectrum and clinical outcome of monoclonal gammopathy of renal significance: A large retrospective case series study from a single institute in China.

OBJECTIVES: To analysis the pathological spectrum and prognosis of monoclonal gammopathy of renal significance (MGRS) patients. METHODS: Patients with renal biopsy-proven MGRS from 1999 to 2017 in Peking University First Hospital were included, clinical data, renal pathology type, treatment and prognosis were collected. RESULTS: One hundred and eighty-seven patients were enrolled, accounting for 0.7% of renal biopsies. Seventy-seven per cent of the MGRS patients were amyloidosis. Eighteen patients (9.6%) were monoclonal immunoglobulin deposition disease. Others included 10 patients (5.3%) with proliferative glomerulonephritis with monoclonal immunoglobulin (G) deposits, seven patients (3.7%) with cryoglobulinaemic glomerulonephritis, five patients (2.6%) with light chain proximal tubulopathy, two patients (1.1%) with fibrillary disease and one patient (0.5%) with C3 glomerulonephritis. Sixty-three per cent were treated with chemotherapy and/or stem cell transplantation. The mean follow-up time was 27 ± 32 months. One patient developed multiple myeloma at 17-month during follow-up. At the end of follow-up, 61 patients (33%) died, and 47 patients (25%) reached end-stage renal disease (ESRD). For the 144 amyloid patients, low estimated glomerular filtration rate (eGFR), decreased blood pressure, presence of cardiac involvement and absence of chemotherapy or high-dose melphalan/autologous peripheral blood stem cell transplantation were identified as independent risk factors for death. Low eGFR, decreased blood pressure, and presence of cardiac involvement were identified as independent risk factors for ESRD. For the 43 non-amyloid patients, no factor was identified for the risk of death. Low eGFR was identified as independent risk factor for ESRD. CONCLUSION: MGRS was an uncommon form of hematologic disorder related renal injury with a wide spectrum of pathologic lesions, and amyloidosis was the most common type. Treatment with chemotherapy and/or high-dose melphalan/autologous peripheral blood stem cell transplantation improved amyloid patients' survival.

Membranoproliferative glomerulonephritis with deposition of monoclonal IgG evolved from polyclonal IgG: a case report with two consecutive renal biopsies.

BACKGROUND: Proliferative glomerulonephritis with monoclonal Immunoglobulin (G) deposits (PGNMID) is a rare kind of MGRS with intact monoclonal IgG deposition. Seventy percent of PGNMID patients were negative for M-spike. CASE PRESENTATION: A 51-year-old Chinese woman presented with 16-month history of chronic nephritic syndrome. Her first biopsy showed a MPGN pattern, and the IF showed polyclonal IgG deposition but with IgG3λ dominance, MGRS was highly suspected. But the serum/urine IFE and bone marrow examination was negative for monoclonal gammopathy. She was treated with RAS inhibitors, and monitored carefully in the outpatient clinic. When the proteinuria was not controlled by RAS inhibitors, immunosuppressive agents were initiated. The second biopsy was done due to her acute kidney injury 9 months later, showing a MPGN pattern with acute tubulointerstitial disease, but the IF showed monoclonal IgG3λ deposition. The κ light chain, IgG1, IgG2 and IgG4 were absent. Electron microscopic examination revealed electron-dense deposits in the mesangial, subendothelial and subepithelial area which is the same as the first renal biopsy. The final diagnose of this patient was PGNMID (IgG3λ) with non-organized deposits. Repeated serum/urine IFE and free light chain still failed to identify monoclonal gammopathy. The patient was treated with steroid and cyclophosphamide, and her serum creatinine decreased. CONCLUSIONS: Some of the PGNMID patients may be derived from polyclonal immune complex mediated glomerulonephritis.

Typing of hereditary renal amyloidosis presenting with isolated glomerular amyloid deposition.

BACKGROUND: The commonly used methods for amyloid typing include immunofluorescence or immunohistochemistry (IHC), which sometimes may come with diagnostic pitfalls. Mass spectrometry (MS)-based proteomics has been recognized as a reliable technique in amyloid typing. CASE PRESENTATION: We reported two middle-aged patients who presented with proteinuria, hypertension and normal renal function, and both had a family history of renal diseases. The renal biopsies of both patients revealed renal amyloidosis with the similar pattern by massive exclusively glomerular amyloid deposition. The IHC was performed by using a panel of antibodies against the common types of systemic amyloidosis, and demonstrated co-deposition of fibrinogen Aα chain and apolipoprotein A-I in the glomerular amyloid deposits of each patient. Then the MS on amyloid deposits captured by laser microdissection (LMD/MS) and genetic study of gene mutations were investigated. The large spectra corresponding to ApoA-I in case 1, and fibrinogen Aα chain in case 2 were identified by LMD/MS respectively. Further analysis of genomic DNA mutations demonstrated a heterozygous mutation of p. Trp74Arg in ApoA-I in case 1, and a heterozygous mutation of p. Arg547GlyfsTer21 in fibrinogen Aα chain in case 2. CONCLUSIONS: The current study revealed that IHC was not reliable for accurate amyloid typing, and that MS-based proteomics and genetic analysis were essential for typing of hereditary amyloidosis.

Mercury-associated glomerulonephritis: a retrospective study of 35 cases in a single Chinese center.

BACKGROUND: Long-term exposure of mercury may induce glomerulonephritis. Clinical and pathological features of mercury-associated glomerulonephritis are not fully clear. This study retrospectively analyzed 35 cases of mercury-associated glomerulonephritis in a single Chinese center. METHODS: Thirty-five patients of mercury-associated glomerulonephritis were enrolled. Clinical data on diagnosis and during follow-up were collected. Plasma anti-phospholipase A2 receptor (PLA2R) antibody, glomerular PLA2R and glomerular IgG subclasses deposition were detected in the cases with membranous nephropathy (MN). RESULTS: Mercury exposure was caused by skin lighting cream (20 patients), mercury-containing pills (9 patients), hair-dyeing agents (4 patients), and unidentified reasons (2 patients). All patients presented with proteinuria and normal renal function. The median of urinary protein was 4.6 (range 1.6~19.7) g/24 h. Twenty-two patients (62.9%) had nephrotic syndrome. Renal histopathology showed minimal change disease (MCD) in 21 patients (60.0%), MN in 13 (37.1%) and focal segmental glomerular sclerosis (FSGS) in 1 patient (2.9%). The proportion of MCD increased along with urinary mercury concentration (P = 0.024). In 13 cases of MN, all patients were negative for plasma anti-PLA2R antibody and glomerular PLA2R antigen. IgG1 (61.5%) and IgG4 (46.2%) deposits were noted along the glomerular capillary loops. Among the 16 patients received mercury detoxification monotherapy, 14 patients received 4.5 ± 2.8 (range 1~12) rounds of regimen and achieved complete remission in 4.5 (range 0.3~23.0) months, 2 patients stayed no remission. CONCLUSIONS: MCD was the most common pathological type of mercury-associated glomerulonephritis, followed by MN. The proportion of MCD increased along with the increase of urinary mercury concentration. Most patients could achieve complete remission after mercury detoxification.

Delayed diagnosis of acromegaly in a patient with focal segmental Glomerulosclerosis: a rare case report and literature review.

BACKGROUND: Experimental studies have demonstrated that hypersecretion of growth hormone (GH) is associated with development of glomerular sclerosis. However, clinical case of such condition is very rare. Here we presented a case of focal segmental glomerulosclerosis (FSGS) associated with acromegaly. CASE PRESENTATION: A 63-year-old man was diagnosed as nephrotic syndrome with minimal change disease for 2 years. Prednisone 1 mg/kg/day for 9 months led to no response. After admission, the second kidney biopsy indicated FSGS (NOS variant). On admission, his acromegalic features were noticed and he complained with a 20-year history of soft tissue swelling of hands and feet. Serum GH and insulin-like growth factor 1 (IGF-1) concentrations were both elevated significantly. An oral glucose tolerance test showed inadequate suppression of serum GH. The presence of a pituitary macroadenoma with a diameter of 1.4 cm by MRI confirmed the diagnosis of acromegaly. Then, the tumor was subtotally removed by trans-sphenoidal surgery. Partial remission of proteinuria was achieved 3 months after surgery and maintained during follow-up, with gradual reduce of corticosteroid. CONCLUSIONS: This rare case suggested that the hypersecretion of GH may participate, at least in part, in FSGS development and progression. Early diagnosis and treatment of acromegaly is beneficial.

Renal involvement in a silicosis patient - case report and literature review.

A 43-year-old Chinese man with a silicosis history was admitted to our hospital due to bilateral lower extremity edema for 1 year, exacerbating with hematuria for 2 months. He started working as a coal miner 30 years ago, and was diagnosed as silicosis 3 months ago. Lab tests revealed hematuria 3+, proteinuria 3+, and a serum creatinine value 2.47 mg/dl on routine check. He was diagnosed with focal proliferative IgA nephropathy (IgAN) and acute tubulo-interstitial nephritis by renal biopsy. He was treated with corticosteroids and got a remission 4 months later. Immunohistochemical staining showed the deposition of macrophage receptor with collagenous structure (MARCO), nod-like receptor pyrin domain-containing-3 (NLRP3), Caspase-1, apoptosis-associated speck (ASC), interleukin (IL)-1ß, and IL-18 in both glomerular and tubulo-interstitial areas. We proposed that the silicon exposure could be related to his kidney disease in the patient and NLRP3 mediated inflammation might be involved in its pathogenesis which needs further explorations.

Rituximab for non-responsive idiopathic membranous nephropathy in a Chinese cohort.

Background: Rituximab had been shown to be effective in inducing remission of nephrotic syndrome in patients with idiopathic membranous nephropathy (iMN). This study applied rituximab therapy for 36 non-responsive iMN patients to investigate its effects and safety. Methods: Thirty-six iMN patients who were non-responsive to prior immunosuppression were enrolled. Rituximab was used for B-cell depletion in patients, with a goal of <5 B cells/mm3 in the circulation. After completing the study, patients were monitored for a median of 12.0 months [interquartile range (IQR) 9.0-19.3]. Results: Fifteen of the 36 (41.7%) patients achieved partial (n = 13) or complete (n = 2) response to the rituximab treatment. The median time for achieving partial response was 4.0 months (IQR 3.0-6.0). The responders had relatively lower levels (118 ± 112 U/mL versus 345 ± 357 U/mL, P = 0.03) of anti-phospholipase 2 receptor (PLA2R) antibodies before the rituximab treatment, and all of them achieved antibody depletion or reduction. B-cell depletion was achieved in all patients. Renal function remained stable in the responders [estimated glomerular filtration rate (eGFR) 53.3 ± 40.5 versus 55.6 ± 33.2 mL/min/1.73 m2, P = 0.67] but deteriorated in the non-responders (eGFR 57.5 ± 29.3 versus 45.3 ± 32.8 mL/min/1.73 m2, P = 0.02) with two patients reaching end-stage kidney disease. Two of the 15 patients relapsed during the follow-up period with anti-PLA2R antibody reoccurrence and B-cell reconstitution. The second course of rituximab combined with tacrolimus induced a faster partial response again in one patient. Conclusion: Rituximab therapy could induce remission of proteinuria and stabilization of renal function in non-responsive iMN patients, even those with damaged renal function. Anti-PLA2R antibodies may be used as a marker for individualized rituximab dosage and treatment monitoring.

T cell responses to peptides of Goodpasture autoantigen in patients with anti-glomerular basement membrane disease.

AIM: Cell-mediated autoimmunity, especially autoreactive T cells, is crucial in the initiation of anti-glomerular membrane (GBM) disease. Epitopes for T cells on Goodpasture autoantigen are not fully defined. This study investigated T cell epitopes in anti-GBM patients, aiming to identify the epitopes and their clinical significance. METHODS: Peripheral blood mononuclear cells (PBMC) were collected from 13 patients with anti-GBM disease. Twenty-four overlapping linear peptides were synthesized covering the whole sequence of human α3(IV)NC1. PBMC response to each peptide was detected by proliferation assay. Their associations with clinical features were further analyzed. RESULTS: Peripheral blood mononuclear cells proliferative responses to linear peptides on α3(IV)NC1 could be detected in all patients. Five major epitopes were identified as stimulatory in over half of the patients: α3(IV)NC1127-148 (P14) (69.2%), α3(IV)NC1159-178 (77.8%), α3(IV)NC1179-198 (55.6%), α3(IV)NC1189-208 (P19) (75.0%) and α3(IV)NC1141-154 (57.1%). P14 and P19 were highly recognized in patients comparing with healthy controls (69.2% vs. 0.0%, P = 0.011; 75.0% vs. 0.0%, P = 0.021, respectively). CONCLUSION: T cell proliferation to linear epitopes was detected in human anti-GBM disease. α3127-148 was a mutual T and B cell epitope, implying its initial role in epitope spreading process.

Monoclonal light chain crystalline podocytopathy and tubulopathy associated with monoclonal gammopathy of renal significance: a case report and literature review.

BACKGROUND: Monoclonal gammopathy of renal significance (MGRS) is a recently defined group of renal diseases caused by monoclonal immunoglobulin secreted by nonmalignant proliferative B cell or plasma cell. Monoclonal immunoglobulin can form different types of structures deposited in renal tissue, including fibrils, granules, microtubules, crystals and casts, and has mostly been reported in multiple myeloma patients. Here we report a rare case with κ light chain crystals in both podocytes and tubular epithelial cells associated with MGRS, which adds more information to the spectrum of MGRS-related renal diseases. CASE PRESENTATION: A 53-year old woman presented with albumin-predominant moderate proteinuria and renal failure. She had monoclonal IgGκ in the serum and monoclonal IgGκ plus free κ in the urine. Multiple myeloma and lymphoproliferative disorders were excluded. Renal biopsy confirmed κ-restricted crystal-storing renal disease involving the podocytes and proximal tubular epithelial cells. The patient was treated with bortezomib followed by lenalidomide-based chemotherapy, and renal function was stable after 1 year of follow-up. CONCLUSIONS: This is a rare case of combined crystalline podocytopathy and tubulopathy associated with MGRS, in which diagnosis was dependent on electron and immuno-electron microscopy.

Increasing frequency of idiopathic membranous nephropathy in primary glomerular disease: a 10-year renal biopsy study from a single Chinese nephrology centre.

AIM: To investigate the changing of idiopathic membranous nephropathy (iMN) in China. METHODS: This study retrospectively analyzed renal disease spectrum of 6049 patients who underwent renal biopsy at Peking University First Hospital from January 2003 to December 2012. The patients were grouped into two periods at a 5-year interval: 2003-2007 (period 1) and 2008-2012 (period 2). RESULTS: Among 6049 renal biopsied patients, 3831 (63.3%) patients were diagnosed as primary glomerular disease (PGD). The proportion of nephrotic syndrome (NS) in PGD was significantly higher in period 2 than that in period 1 (1016/2214 [55.0%] vs 682/1617 [42.2%], P = 0.022). The proportion of iMN in PGD increased from 16.8% (217/1617) in period 1 to 29.35% (646/2214) in period 2 in all groups of age (P < 0.001). There was no significant difference of clinical characteristics including age, gender, hypertension, serum cholesterol and proteinuria between the two periods (P > 0.05). However, in young patients with iMN (14-44 years old), the percentage of renal histopathology stage I and stage II of iMN in PGDs was significantly higher in period 2 than that in period 1 (101/1240 [8.15%] vs 210/1340 [15.7%], P < 0.001). CONCLUSION: Our study suggests that the frequency of iMN in PGD in our referral diagnostic centre has doubled over the past 10 years. The increase of adult iMN is mainly due to the increase of early stages of iMN in young patients.

Immunoglobulin repertoire sequencing and de novo sequencing - Powerful tools for identifying free light chains from patients with light chain cast nephropathy.

In patients with light chain cast nephropathy (LCCN), abundantly produced monoclonal immunoglobulin free light chains (FLCs) play a vital role in pathogenesis. Determining the precise sequences of patient-derived FLCs is therefore highly desirable. Although immunoglobulin repertoire sequencing (5' RACE-seq) has been proven to be sensitive enough to provide full-length V(D)J region (variable, diversity and joining genes) of FLCs using bone marrow samples, an invasive and bone marrow independent method is still in demand. Here a de novo sequencing workflow based on the bottom-up proteomics for patient-derived FLCs was established. PEAKS software was used for the de novo sequencing of peptides that were further assembled into full-length FLC sequences. This de novo protein sequencing method can obtain the full-length amino acid sequences of FLCs, and had been shown to be as reliable as 5' RACE-seq. The two LCCN sequences derived from above the two methods were identical, and they possessed more hydrophobic or nonpolar amino acids compared with the corresponding germline, which may be associated with the pathogenesis.

Proteinase­3­antineutrophil cytoplasmic antibody­associated vasculitis secondary to subacute infective endocarditis: A case report.

A 58-year-old male patient was admitted to Peking University First Hospital (Beijing, China) due to recurrent hematuria, proteinuria and kidney dysfunction. The patient was positive for proteinase-3 (PR3)-antineutrophil cytoplasmic antibody (ANCA). Pathology of the kidney showed focal proliferative necrotizing glomerulonephritis with crescent formation and immune complex-mediated glomerulonephritis. The patient was diagnosed with PR3-ANCA-associated vasculitis (AAV), received intensive immunosuppressive therapy and experienced two relapses within 1 year. After admission, aortic valve vegetation was observed via echocardiography. The patient subsequently received antibiotic treatment and valve replacement, and achieved complete remission of kidney and cardiac function. The present case emphasized the importance of identifying secondary reasons for ANCA formation, especially infective endocarditis in patients with PR3-AAV.

Characteristics of Complement Protein Deposition in Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposition.

BACKGROUND: Hypocomplementemia and complement co-deposition with monoclonal immunoglobulins in glomeruli are not rare in proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID). Deposition of monoclonal immunoglobulins in glomeruli has been suggested to activate complement and cause kidney injury. However, the profiles of complement activation in PGNMID and their clinical and pathologic significance need to be clarified. METHODS: Forty-six patients with PGNMID were enrolled. Proteomic analysis of glomeruli using laser microdissection and mass spectrometry was performed for ten patients with PGNMID to determine the composition of glomerular deposits. Kidney deposition of complement components was detected by immunohistochemistry and immunofluorescence. Urinary and plasma levels of complement components were measured by an enzyme-linked immunosorbent assay. Group differences were assessed using t tests or Mann-Whitney U tests depending on the distribution. Correlation analysis was performed using Spearman rank correlation or Pearson correlation. RESULTS: Laser microdissection and mass spectrometry-based proteomic analysis showed that complement components were the most enriched proteins deposited in the glomeruli of patients with PGNMID. Glomerular deposition of C3c, C4d, and C5b-9 was detected in most patients. Levels of urinary and plasma C3a, C5a, soluble C5b-9, C4d, Bb, and C1q as well as urinary mannose-binding lectin were significantly higher in patients with PGNMID compared with healthy controls. The intensity of C3c and C4d deposition in glomeruli correlated with serum creatinine and the percentage of crescents, respectively. Furthermore, levels of urinary complement components correlated positively with serum creatinine, urinary protein excretion, percentage of crescents, and global glomerulosclerosis in kidney biopsies, whereas plasma levels of most complement components did not show a significant correlation with clinicopathologic parameters. In multivariable analysis, a higher level of urinary C4d was identified as an independent risk factor of kidney failure. CONCLUSIONS: The complement system was found to be overactivated in PGNMID, and levels of urinary complements correlated with disease severity. A higher level of urinary C4d was identified as an independent risk factor of kidney failure.

Clinicopathological and immunological features of new onset kidney disease: a rare event after SARS-CoV-2 vaccination.

The onset of various kidney diseases has been reported after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. However, detailed clinical and pathological features are lacking. We screened and analyzed patients with newly diagnosed kidney diseases after inactivated SARS-CoV-2 vaccination in Peking University First Hospital from January 2021 to August 2021, and compared them with the reported cases in the literature. We obtained samples of blood, urine and renal biopsy tissues. Clinical and laboratory information, as well as light microscopy, immunostaining and ultrastructural observations, were described. The SARS-CoV-2 spike protein and nucleoprotein were stained using the immunofluorescence technique in the kidney biopsy samples. SARS-CoV-2 specific antibodies were tested using magnetic particle chemiluminescence immunoassay. The study group included 17 patients with a range of conditions including immune-complex-mediated kidney diseases (IgA nephropathy, membranous nephropathy and lupus nephritis), podocytopathy (minimal change disease and focal segmental glomerulosclerosis) and others (antineutrophil-cytoplasmic-antibody-associated vasculitis, anti-glomerular basement membrane nephritis, acute tubulointerstitial nephritis and thrombotic microangiopathy). Seven patients (41.18%) developed renal disease after the first dose and ten (58.82%) after the second dose. The kidney disease spectrum as well as clinicopathological features are similar across different types of SARS-CoV-2 vaccines. We found no definitive evidence of SARS-CoV-2 spike protein or nucleoprotein deposition in the kidney biopsy samples. Seropositive markers implicated abnormal immune responses in predisposed individuals. Treatment and follow-up (median = 86 days) showed that biopsy diagnosis informed treatment and prognosis in all patients. In conclusion, we observed various kidney diseases following SARS-CoV-2 vaccine administration, which show a high consistency across different types of SARS-CoV-2 vaccines. Our findings provide evidence against direct vaccine protein deposition as the major pathomechanism, but implicate abnormal immune responses in predisposed individuals. These findings expand our understanding of SARS-CoV-2 vaccine renal safety.

Acute kidney injury and bilateral symmetrical enlargement of the kidneys as first presentation of B-cell lymphoblastic lymphoma.

Lymphoblastic lymphoma is an uncommon subtype of lymphoid neoplasm in adults. Acute kidney injury at initial presentation due to lymphoblastic lymphoma infiltration of the kidneys has rarely been described. We report a 19-year-old woman who presented with acute kidney injury due to massive lymphomatous infiltration of the kidneys. The diagnosis of B-cell lymphoblastic lymphoma was established by immunohistochemical study of the biopsied kidney. The patient had an excellent response to the VDCLP protocol (vincristine, daunomycin, cyclophosphamide, asparaginase, and dexamethasone) with sustained remission. We recommend that lymphomatous infiltration be considered in patients presenting with unexplained acute kidney injury and enlarged kidneys.