Neural Epidermal Growth Factor-Like 1 Protein-Positive Membranous Nephropathy in Chinese Patients.

The neural EGF-like 1 (NELL-1) protein is a novel antigen in primary membranous nephropathy. The prevalence and clinical characteristics of NELL-1-positive membranous nephropathy in Chinese individuals with primary membranous nephropathy are unclear. A total of 832 consecutive patients with biopsy-proven primary membranous nephropathy were enrolled. The glomerular expression of phospholipase A2 receptor (PLA2R) and thrombospondin type 1 domain-containing 7A (THSD7A) was screened. Glomerular immunohistochemistry staining for NELL-1 was performed in 43 patients with PLA2R- and THSD7A-negative membranous nephropathy, 31 patients with PLA2R-positive membranous nephropathy, and two patients with PLA2R and THSD7A double positivity. The NELL-1 antibody was also detected in the sera of patients with NELL-1-positive membranous nephropathy by western blot. Clinical and pathologic features were comparable between patients with isolated NELL-1-positive, isolated PLA2R/THSD7A-positive, and triple antigen-negative membranous nephropathy. Among the 832 patients with primary membranous nephropathy, 11 of 54 (20%) patients with PLA2R-negative membranous nephropathy had THSD7A-positive membranous nephropathy. NELL-1-positive membranous nephropathy accounted for 35% (15 of 43) of all patients with PLA2R- and THSD7A-negative membranous nephropathy. One patient was double positive for NELL-1 and PLA2R in glomerular deposits and positive for only the PLA2R antibody in the serum. Most patients with NELL-1-positive membranous nephropathy were women. No tumors were found. There were significant differences in the prevalence of IgG subtypes between patients with different antigen positivity. Among patients with isolated NELL-1-positive membranous nephropathy, although 80% (12 of 15) were IgG4 staining positive, the proportion of IgG4 dominance was only 67% (ten of 15). About one third of patients who were PLA2R and THSD7A negative were NELL-1 positive in Chinese patients with primary membranous nephropathy. NELL-1-positive membranous nephropathy was more common than THSD7A-positive membranous nephropathy in PLA2R-negative membranous nephropathy.

Wang G ，Sun L ，Dong H ，Wang Y ，Xu X ，Zhao Z ，Cheng W ，Liu X ，Zhao X ，Geng Y ，Bao S ，Chen Y ，Cheng H ... -  《-》

Circulating Antibodies against Thrombospondin Type-I Domain-Containing 7A in Chinese Patients with Idiopathic Membranous Nephropathy.

Thrombospondin type-I domain-containing 7A (THSD7A) was recently identified as the target antigen in about 10% of patients with M-type phospholipase A2 receptor (PLA2R)-negative membranous nephropathy in European and North American populations. The prevalence of THSD7A in other populations and their clinical associations deserve further clarification. Immunofluorescence assay was performed to investigate anti-THSD7A antibodies in 578 consecutive patients with biopsy-proven idiopathic membranous nephropathy, 114 patients with secondary membranous nephropathy, 64 disease controls, and 20 healthy controls. Glomerular expression of THSD7A antigen was examined by immunohistochemistry. Anti-PLA2R antibodies and glomerular PLA2R expression were also screened. Among the 578 patients with idiopathic membranous nephropathy, 12 (2%) patients were identified as THSD7A-positive: ten patients were THSD7A-positive alone, which accounted for 16% (ten of 64) of PLA2R-negative patients; two patients were dual-positive for both anti-THSD7A and anti-PLA2R antibodies and showed enhanced expression of both antigens colocalized in glomeruli. Among the 114 patients with secondary membranous nephropathy, one among 44 (2%) patients with cancer had anti-THSD7A antibodies, whereas 18 of 44 (41%) had anti-PLA2R antibodies. No anti-THSD7A antibody was detected in other disease controls or healthy individuals. Clinical features were comparable between the patients with and without THSD7A. During follow-up, two patients who achieved remission had a clearance of circulating antibodies against THSD7A, whereas antibodies increased in parallel with proteinuria in a patient with a relapse. THSD7A-associated membranous nephropathy has a low prevalence in Chinese patients. The double-positive patients suggest dual autoimmune responses.

Wang J ，Cui Z ，Lu J ，Probst C ，Zhang YM ，Wang X ，Qu Z ，Wang F ，Meng LQ ，Cheng XY ，Liu G ，Debiec H ，Ronco P ，Zhao MH ... -  《-》

Neural epidermal growth factor-like 1 protein (NELL-1) associated membranous nephropathy.

Membranous nephropathy is characterized by deposition of immune complexes along the glomerular basement membrane. PLA2R and THSD7A are target antigens in 70% and 1-5% of primary membranous nephropathy cases, respectively. In the remaining cases, the target antigen is unknown. Here, laser microdissection of glomeruli followed by mass spectrometry was used to identify novel antigen(s) in PLA2R-negative membranous nephropathy. An initial pilot mass spectrometry study in 35 cases of PLA2R-negative membranous nephropathy showed high spectral counts for neural tissue encoding protein with EGF-like repeats, NELL-1, in six cases. Mass spectrometry failed to detect NELL-1 in 23 PLA2R-associated membranous nephropathy and 88 controls. NELL-1 was localized by immunohistochemistry, which showed bright granular glomerular basement membrane staining for NELL-1 in all six cases. Next, an additional 23 NELL-1 positive cases of membranous nephropathy were identified by immunohistochemistry in a discovery cohort of 91 PLA2R-negative membranous nephropathy cases, 14 were confirmed by mass spectrometry. Thus, 29 of 126 PLA2R-negative cases were positive for NELL-1. PLA2R-associated membranous nephropathy and controls stained negative for NELL-1. We then identified five NELL-1 positive cases of membranous nephropathy out of 84 PLA2R and THSD7A-negative cases in two validation cohorts from France and Belgium. By confocal microscopy, both IgG and NELL-1 co-localized to the glomerular basement membrane. Western blot analysis showed reactivity to NELL-1 in five available sera, but no reactivity in control sera. Clinical and biopsy findings of NELL-1 positive membranous nephropathy showed features of primary membranous nephropathy. Thus, a subset of membranous nephropathy is associated with accumulation and co-localization of NELL-1 and IgG along the glomerular basement membrane, and with anti-NELL-1 antibodies in the serum. Hence, NELL-1 defines a distinct type of primary membranous nephropathy.

Sethi S ，Debiec H ，Madden B ，Charlesworth MC ，Morelle J ，Gross L ，Ravindran A ，Buob D ，Jadoul M ，Fervenza FC ，Ronco P ... -  《-》

Podocyte Antigen Staining to Identify Distinct Phenotypes and Outcomes in Membranous Nephropathy: A Retrospective Multicenter Cohort Study.

Membranous nephropathy (MN) is characterized by the deposition of immune complexes along glomerular basement membranes. M-Type phospholipase A2 receptor (PLA2R), thrombospondin type 1 domain-containing 7A (THSD7A), exostosin 1 and 2 (EXT1/2), and neural epidermal growth factor-like 1 protein (NELL-1) have been identified as established or potential podocyte antigens in MN. We investigated the association of podocyte antigen staining with MN clinical phenotype and outcomes. Multicenter retrospective cohort study. 177 consecutive patients with MN unrelated to lupus erythematosus, identified after screening of 3,875 native kidney biopsies performed in the Belgian UCLouvain Kidney Disease Network from 2000 through 2018. Positive immunostaining for podocyte antigens on archived kidney biopsy samples. Association with different phenotypes (baseline characteristics of patients and pathologic findings on kidney biopsy), time to cancer and to kidney failure. Kaplan-Meier estimates and Cox regression analyses to assess time to cancer and kidney failure. 177 patients were followed up for a median of 4.0 (IQR, 1.3-8.0) years. Diagnosis of PLA2R-positive (PLA2R+), THSD7A+, and double-negative (PLA2R-/THSD7A-) MN was made in 117 (66.1%), 6 (3.4%), and 54 (30.5%) patients, respectively. Progression to kidney failure was similar in all groups. Although the number of patients with THSD7A+MN was small, they showed a higher incidence (50%) and increased risk for developing cancer during follow-up (adjusted HR, 5.0 [95% CI, 1.4-17.9]; P=0.01). 8% and 5% of patients with double-negative MN stained positively for EXT1/2 and NELL-1, respectively. Most patients with EXT1/2+MN were women, had features of systemic autoimmunity, and showed glomerular C1q deposits. Retrospective design; small number of patients in the THSD7A group; lack of evaluation of immunoglobulin G subclasses deposition. Our real-world data describe the relative prevalence of subgroups of MN and support the hypothesis that a novel classification of MN based on podocyte antigen staining may be clinically relevant.

Hanset N ，Aydin S ，Demoulin N ，Cosyns JP ，Castanares-Zapatero D ，Crott R ，Cambier JF ，Pochet JM ，Gillerot G ，Reginster F ，Houssiau F ，Debiec H ，Ronco P ，Jadoul M ，Morelle J ，UCLouvain Kidney Disease Network ... -  《-》

[Clinical Significance of Thrombospondin Type 1 Domain-Containing 7A and Neural Epidermal Growth Factor-Like 1 Protein in M-Type Phospholipase A2 Receptor-Negative Membranous Nephropathy].

Tang XL ，DU YY ，Yu J ，Ye T ，Zhu H ，Chen YF ，Li XH ... -  《-》