Research Laboratory in Immunology of Renal Transplantation and Immunopathology (LR03SP01), Charles Nicolle Hospital, Tunis El Manar University, Tunis, Tunisia.
Department of Nephrology and Internal Medicine, Charles Nicolle Hospital, Tunis, Tunisia.
PLoS One. 2020 Oct 1;15(10):e0240025. doi: 10.1371/journal.pone.0240025. eCollection 2020.
Primary membranous nephritis (PMN) is an autoimmune disease induced by the deposit of antibodies (Ab) to the phospholipase receptor A2 receptor (PLA2R) on podocytes. In this context, we aimed to assess the relationships between anti-PLA2R Ab, PLA2R rs4664308 SNP, PLA2R mRNA levels and PMN susceptibility and outcome.
Sixty-eight PMN patients, 30 systemic lupus erythematosus (SLE) patients with secondary MN and 30 healthy control subjects served for anti-PLA2R Ab measurement by ELISA and PLA2R rs4664308 SNP genotyping by a commercial real-time PCR. Twenty patients with tubulo-interstitial nephritis (TIN) were used as controls for renal PLA2R mRNA quantification in PMN patients from kidney biopsies. PLA2R mRNA quantification was carried-out by real-time PCR after RNA extraction.
Forty-three (63.2%) PMN patients received initial therapy consisting of alternating monthly cycles of corticosteroids and cyclophosphamide. Twelve (17.6%) patients had resistant PMN to initial therapy and were consecutively treated by cyclosporine or tacrolimus. Anti-PLA2R Ab were positive in 54 (79.4%) PMN patients, while all SLE patients and controls were negative, p<0.0001. Moreover, anti-PLA2R Ab levels were significantly higher in PMN patients (134.85 [41.25-256.97] RU/ml) than in SLE patients (3.35 [2.3-4.35] RU/ml) and controls (2 [2-2.3]), p<0.0001. Consequently, a ROC curve showed for 100% specificity a sensitivity of 94.1% at a threshold of 2.6 RU/ml. Besides, Anti-PLA2R antibodies levels were significantly associated to non-remission; p = 0.002. The rs4664308*A wild-type allele was significantly more frequent in PMN patients (0.809) than in controls (0.633) and SLE patients (0.65); p = 0.008, OR [95% CI] = 2.44 [1.24-4.82] and p = 0.016, OR [95% CI] = 2.27 [1.15-4.5], respectively. Renal PLA2R mRNA levels were significantly higher in PMN patients (218.29 [66.05-486.07]) than in TIN patients (22.09 [13.62-43.34]), p<0.0001. Moreover, PLA2R mRNA levels were significantly higher in non-remission patients (fold-factor vs. partial remission = 2.46 and fold-factor vs. complete remission = 12.25); p = 1.56 10E-8. In addition, PLA2R mRNA and anti-PLA2R Ab levels were significantly correlated, Spearman Rho = 0.958, p<0.0001.
Anti-PLA2R Ab and renal PLA2R mRNA could be useful markers for PMN outcome predicting. The PLA2R rs6446308 SNP is associated with PMN susceptibility in Tunisians.
原发性膜性肾病（PMN）是一种由足细胞上的磷脂酶 A2 受体（PLA2R）抗体（Ab）沉积引起的自身免疫性疾病。在这种情况下，我们旨在评估抗 PLA2R Ab、PLA2R rs4664308 SNP、PLA2R mRNA 水平与 PMN 易感性和结局之间的关系。
68 名 PMN 患者、30 名继发于系统性红斑狼疮（SLE）的 MN 患者和 30 名健康对照者用于通过 ELISA 测量抗 PLA2R Ab，并通过商业实时 PCR 对 PLA2R rs4664308 SNP 进行基因分型。20 名肾小管间质性肾炎（TIN）患者用作 PMN 患者肾组织 PLA2R mRNA 定量的对照。通过 RNA 提取后进行实时 PCR 进行 PLA2R mRNA 定量。
43 名（63.2%）PMN 患者接受了初始治疗，包括交替进行每月一次的皮质类固醇和环磷酰胺周期。12 名（17.6%）PMN 患者对初始治疗有耐药性，随后连续接受环孢素或他克莫司治疗。54 名（79.4%）PMN 患者抗 PLA2R Ab 阳性，而所有 SLE 患者和对照组均为阴性，p<0.0001。此外，PMN 患者的抗 PLA2R Ab 水平明显高于 SLE 患者（3.35 [2.3-4.35] RU/ml）和对照组（2 [2-2.3] RU/ml），p<0.0001。因此，ROC 曲线显示，在阈值为 2.6 RU/ml 时，特异性为 100%，灵敏度为 94.1%。此外，抗 PLA2R 抗体水平与非缓解显著相关；p = 0.002。rs4664308*A 野生型等位基因在 PMN 患者中（0.809）比对照组（0.633）和 SLE 患者（0.65）更常见；p = 0.008，OR [95%CI] = 2.44 [1.24-4.82] 和 p = 0.016，OR [95%CI] = 2.27 [1.15-4.5]。PMN 患者的肾 PLA2R mRNA 水平明显高于 TIN 患者（218.29 [66.05-486.07]），p<0.0001。此外，非缓解患者的 PLA2R mRNA 水平明显高于部分缓解患者（倍数因子与部分缓解=2.46，倍数因子与完全缓解=12.25）；p = 1.56 10E-8。此外，PLA2R mRNA 和抗 PLA2R Ab 水平呈显著相关，Spearman Rho = 0.958，p<0.0001。
抗 PLA2R Ab 和肾 PLA2R mRNA 可作为预测 PMN 结局的有用标志物。PLA2R rs6446308 SNP 与突尼斯人 PMN 的易感性有关。
