Membranous Nephropathy Medical Services in China

Membranous Nephropathy (MN) is a chronic autoimmune kidney disorder characterized by the thickening of the glomerular basement membrane due to immune complex deposition—primarily IgG and complement component C3—along the subepithelial surface of podocytes. This leads to podocyte injury, disruption of the filtration barrier, and consequent heavy proteinuria, often presenting as nephrotic syndrome (edema, hypoalbuminemia, hyperlipidemia, and thrombotic risk). MN is classified as primary (idiopathic, ~75% of cases) when no underlying cause is identified, or secondary when associated with conditions such as systemic lupus erythematosus, hepatitis B or C infection, solid tumors (e.g., lung, gastric, or colorectal cancers), autoimmune thyroid disease, or exposure to certain medications (e.g., NSAIDs, penicillamine, or gold salts). Pathogenesis centers on autoantibodies targeting podocyte antigens—most commonly phospholipase A2 receptor (PLA2R) in adults (found in ~70–80% of primary MN), and less frequently thrombospondin type-1 domain-containing 7A (THSD7A) or neural epidermal growth factor-like 1 (NELL-1). These antibodies trigger complement activation (via the lectin or alternative pathways), resulting in subepithelial immune deposits, podocyte foot process effacement, and progressive protein leakage. Epidemiologically, MN is the most common cause of adult-onset nephrotic syndrome in non-diabetic populations, with an incidence of approximately 8–10 cases per million per year globally. It peaks between ages 40–60, shows a male predominance (M:F ≈ 2:1), and exhibits higher prevalence in North America and Europe compared to Asia—though incidence in China is rising, likely reflecting improved diagnostic awareness and PLA2R testing availability. Key risk factors include older age, male sex, PLA2R antibody titer level and persistence, elevated serum creatinine at diagnosis, and non-immunologic comorbidities such as hypertension and obesity. Importantly, up to one-third of untreated patients experience spontaneous remission within 5 years; however, another third progress to end-stage kidney disease over 10–15 years without intervention. Quality of life is significantly impaired: persistent edema and fatigue limit physical activity and work capacity; recurrent infections and hypercoagulability increase hospitalization risk; dietary restrictions (low-salt, low-protein) affect psychosocial well-being; and long-term immunosuppression carries risks of diabetes, osteoporosis, cataracts, and malignancy. Patients also face anxiety related to unpredictable disease course, fertility concerns, and financial burden from repeated lab monitoring (PLA2R titers, urine protein-to-creatinine ratio), renal biopsies, and prolonged therapy. Early diagnosis via serologic testing (anti-PLA2R/THSD7A) and confirmatory kidney biopsy remains critical for risk stratification and timely, individualized treatment.

Membranous nephropathy (MN) is an immune-mediated glomerular disease characterized by subepithelial immune complex deposition, leading to thickening of the glomerular basement membrane and clinical manifestations ranging from asymptomatic proteinuria to nephrotic syndrome. It is the most common cause of primary nephrotic syndrome in adults. Management requires a risk-stratified, individualized approach integrating clinical, histopathological, and serological data—including anti-PLA2R and anti-THSD7A antibody titers—to guide therapeutic decisions. Treatment strategies fall broadly into conservative management, pharmacologic immunosuppression, and supportive care; surgical intervention has no role in MN, as it is not amenable to resection or bypass.

Conservative treatment forms the cornerstone for low-risk patients—typically those with persistent proteinuria <4 g/day, stable estimated glomerular filtration rate (eGFR), and absence of hypertension or edema. This includes strict blood pressure control targeting <130/80 mmHg using angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II receptor blockers (ARBs), which reduce intraglomerular pressure and proteinuria independently of antihypertensive effects. Dietary sodium restriction (<2 g/day) enhances diuretic efficacy and mitigates volume overload. Statin therapy is recommended for all patients with nephrotic-range proteinuria to manage dyslipidemia and confer potential renoprotective benefits. Smoking cessation, weight optimization, and influenza/pneumococcal vaccination are essential components of long-term renal protection. Approximately 30% of untreated patients experience spontaneous remission within 5 years, underscoring the appropriateness of initial observation in carefully selected cases.

Pharmacologic therapy is indicated for high-risk patients: those with persistent proteinuria ≥4 g/day for >6 months, declining eGFR (>15% decline/year), or progressive hypoalbuminemia (<2.5 g/dL). First-line immunosuppression follows evidence-based protocols. The Ponticelli regimen—alternating monthly cycles of oral prednisone and intravenous cyclophosphamide—is historically effective but carries significant gonadal toxicity, hemorrhagic cystitis, and malignancy risks. Contemporary guidelines increasingly favor rituximab, a chimeric anti-CD20 monoclonal antibody. The MENTOR trial demonstrated superior complete remission rates (65% vs. 19%) and improved safety over cyclosporine at 24 months, establishing rituximab as first-line for PLA2R-positive MN. Dosing typically involves two 1-g infusions separated by 2 weeks or four weekly 375 mg/m² doses; repeat dosing is guided by CD19+ B-cell repopulation and anti-PLA2R titer trends. For rituximab-ineligible or refractory patients, calcineurin inhibitors (tacrolimus or cyclosporine) combined with low-dose corticosteroids remain viable alternatives, though require vigilant monitoring for nephrotoxicity, hypertension, and new-onset diabetes. Mycophenolate mofetil (MMF) shows modest efficacy in small trials but lacks robust comparative data and is generally reserved for contraindications to first-line agents. Emerging therapies—including anti-BAFF agents (e.g., belimumab) and complement inhibitors (e.g., iptacopan)—are under active investigation in phase II/III trials.

Surgical treatment has no established indication in membranous nephropathy. MN is a systemic autoimmune disorder affecting glomerular capillary walls—not a localized structural lesion—and therefore cannot be corrected via nephrectomy, shunt placement, or transplantation as primary therapy. Kidney transplantation may be considered in end-stage kidney disease (ESKD), but recurrence rates exceed 30%, particularly in PLA2R-positive recipients. Pre-transplant anti-PLA2R titer reduction and post-transplant rituximab prophylaxis are being explored to mitigate recurrence risk.

China offers distinct advantages in MN management, rooted in integrated clinical infrastructure, large-scale biomarker validation, and innovative therapeutic implementation. Chinese nephrology centers have pioneered real-world validation of anti-PLA2R assays across diverse ethnic cohorts, refining risk prediction models applicable to Asian populations. National registries such as the China Chronic Kidney Disease (C-CKD) Network enable longitudinal outcome tracking and rapid dissemination of best practices. Rituximab is widely accessible and reimbursed under China’s National Reimbursement Drug List (NRDL), significantly improving affordability compared to Western markets. Moreover, China leads in pragmatic trials evaluating abbreviated rituximab regimens and biosimilar rituximab—demonstrating non-inferior efficacy and enhanced cost-effectiveness without compromising safety. Traditional Chinese Medicine (TCM) adjuncts, such as tripterygium glycosides (Lei Gong Teng), are used in select centers under rigorous quality control; meta-analyses suggest synergistic proteinuria reduction when combined with low-dose steroids, though hepatotoxicity and gonadal suppression necessitate close monitoring. Multidisciplinary nephrology teams—including dietitians, pharmacists, and TCM specialists—facilitate holistic, patient-centered care aligned with national chronic disease management standards.

Recovery and long-term follow-up emphasize sustained remission monitoring and complication prevention. Patients achieving remission require quarterly assessment of urine protein-to-creatinine ratio (UPCR), serum albumin, creatinine, and anti-PLA2R titers for at least 3 years; relapse is defined as UPCR >3.5 g/g after confirmed remission. Blood pressure and lipid profiles must be maintained within target ranges indefinitely. Vaccination status—particularly pneumococcal, hepatitis B, and annual influenza—should be updated pre- and post-immunosuppression. Patients on rituximab require screening for hepatitis B virus (HBV) reactivation and baseline immunoglobulin levels to identify hypogammaglobulinemia risk. Lifestyle counseling remains critical: moderate-intensity aerobic exercise (150 min/week), plant-predominant low-sodium diets, and avoidance of NSAIDs and contrast media unless absolutely necessary. Psychosocial support is integral—nephrotic syndrome imposes substantial emotional burden, and depression/anxiety screening should be routine. Finally, women of childbearing potential require preconception counseling regarding teratogenic risks of immunosuppressants and optimal timing for pregnancy (ideally after sustained remission >12 months off cytotoxic agents). With contemporary risk-adapted strategies, over 70% of patients achieve partial or complete remission within 2–3 years, preserving native kidney function and markedly reducing progression to ESKD.