Detection And Clinical Significance Of PLA₂R And IgG Subclasses In Membranous Nephropathy Tissues

Objective: Here we evaluated the phospholipase A2 receptor(PLA2R)and Ig G subclasses in glomerular deposits of membranous nephropathy.In order to explore the method to classify idiopathic membranous nephropathy(IMN)and the secondary membranous nephropathy(SMN).And also observed the relationship between PLA2 R expression in glomerular deposits and clinical significance.Methods: Patients were identified on the basis of the renal biopsy files at the Department of Nephrology in Okayama University Hospital,Japan.All the patients who were diagnosed with MN between 2012 and 2015 were observed for 6 months.A total of 42 patients were included.13 of the 42 cases were IMN patients.And another 29 cases were SMN which including 14 with lupus nephritis case,3 with drug-induced cases,4 with other autoimmune disease,3 with infection cases,3 with maligancy cases and 2 with GVHD cases.Basic clinical information of all the research subjects,including gender,age,body mass index,medical history and so on was collected.Albumin,serum creatinie,and urinary protein(24-hour)were assessed by autobiochemistry machine.e GFR was calculated by new JSN-CKDI(2008)equation.Percutaneous renal biopsy was performed in each patient and slides were made from pathological sample specimens.Pathological observation by light microscope,immunofluorescence(IF)and electron microscope were then made by senior pathologists in our department.The light microscope expressions were including mesangial proliferation,endocapillary proliferation,extralcallibary proliferation,segmental screlosis,tubulointerstitial injury,and globalscrelosis.We used 0-1 scores to measure the expression,1 as positive finding,0 as negative finding.Electron microscope examinations maily used to do the Ehrenreich-Churg stages.PLA2 R expression was examined by indirect IF using rabbit polyclonal anti-PLA2 R antibodies,followed by Alexa Fluor 488-conjugated goat polyclonal anti-rabbit Ig G Antibodies.We used the direct IF assay to detect the Ig G subclasses with FITC-conjugated mouse anti-human Ig G1(Fc),Ig G2(Fab),Ig G3(F(ab')2)and IgG4(p Fc)monoclonal antibodies.All the fluorescence intensity of glomerular staining was graded as semi-quantitative scores as follows: negative =0;weakly positive=1;positive=1;strong positive=2.The reduction of proteinuria and renal function were analyzed in both PLA2R?1 and PLA2R<1 groups for 6 months.Results: 1.A total of 42 MN patients were included.13 of the 42 cases were IMN patients.And another 29 cases were SMN which including 48.3%(14/29)with lupus nephritis case,13.8%(4/29)with other autoimmune disease,10.3%(3/29)with infection cases,10.3%(3/29)with drug-induced cases,10.3%(3/29)with maligancy cases and6.9%(2/29)with GVHD cases.2.Female number in SMN group was bigger than IMN group.The averaged age of IMN was higher than SMN patients(65.0±17.7 vs 51.7±18.0,P<0.05);BP,Albumin,Serum creatinie,Urinary protein(24-hour)and e GFR,Prednisone usage ratio,Immunosuppressive agents usage ratio have no difference in statistics(P>0.05).3.PLA2 R in IMN group expressed higher than SMN group on IF assay(P<0.05);IgG4 in IMN group was higher than SMN group(P< 0.05).PLA2R(sensitivity,61.5%)was lower than IgG4(sensitivity,84.6%).PLA2R(specificity,69%)was higher than IgG4(specificity,55.2%)4.IMN group PLA2R(+)IgG4(+): n=8(61.5%);PLA2R(-)IgG4(-): n=2(15.4%);PLA2R(+)IgG4(-):n=0;IgG4(+)PLA2R(-):n=3(23.1%).SMN group PLA2R(+)IgG4(+):n=5(17.2%),PLA2R(-)IgG4(-):n=12(41.4%),PLA2R(+)IgG4(-):n=4(13.8%),IgG4(+)PLA2R(-):n=8(27.6%).PLA2 R and IgG4 double(+)in IMN group were higher than SMN group(61.5% vs17.2%,p<0.05);PLA2R and IgG4 double(-)in IMN group were lower than SMN group(15.4% vs 41.4%,P<0.05).5.The Up/Ugcr average before treatment in PLA2R?1 group was higher than PLA2R<1 group(6.4 vs 3.1),after 6 months' treatment the Up/Ugcr average between two groups were almost same(1.8 vs 1.9).The avearaged e GFR before treatment in PLA2R?1 group and PLA2R<1 group were almost same(61.8 vs 60.4)and after 6months' treatment the e GFR average was also almost similar(69.8 vs 63.3)Conclusions:1.The intensity of PLA2 R and IgG4 is significantly increased in patients with IMN compared with SMN2.The assessment of PLA2 R before treatment in glomerular deposits has no relationship between Up/Ugcr and e GFR of MN patients after 6 months' treatment.