Colquhounia Root Tablets Reduce Proteinuria and Regulate Immune Inflammation in Low-Risk Primary Membranous Nephropathy: A Randomized Trial

Background: To evaluate the clinical efficacy of Colquhounia root tablets (CRT) in patients with low-risk primary membranous nephropathy (PMN) and to investigate the underlying immunoinflammatory mechanisms. Methods: This prospective, randomized, controlled pilot study enrolled 30 patients with biopsy-confirmed low-risk PMN, defined as 24-h urine total protein (UTP) < 4 g/24 h and estimated glomerular filtration rate ≥ 60 mL/min/1.73 m 2 . Patients were randomized 1:1 to irbesartan alone (control group) or irbesartan combined with CRT (treatment group). All patients completed 6 months of treatment and 3 months of follow-up. The primary endpoints were 24-h UTP and serum albumin levels assessed over time. Secondary outcomes included anti-M-type phospholipase A2 receptor antibodies (PLA2R-Ab), renal function, blood lipid levels, urine red blood cell count (URBC), inflammatory and immune markers (T and B cells, immune proteins), safety parameters (liver and hematologic function), and adverse events. Results: Compared with the control group, the treatment group exhibited a greater reduction in 24-h UTP (64.7% vs. 21.4%) and a higher PLA2R-Ab seroconversion rate (50.0% vs. 12.5%). Serum albumin increased significantly from baseline within the treatment group, and improvements in URBC and immunoinflammatory markers were observed. At Month 6, Interleukin-6 (IL-6) and Tumor Necrosis Factor-α (TNF-α) were significantly lower in the treatment group than in the control group, whereas other immunological and renal function parameters showed favorable trends without consistent significant between-group differences. No significant between-group differences were observed in overall renal function or safety parameters. Adverse events were mild in both groups. Conclusion: In this small, single-center pilot study, CRT added to irbesartan was associated with favorable improvements in proteinuria and selected immunoinflammatory markers in patients with low-risk PMN compared with irbesartan alone. These exploratory findings suggest potential adjunctive benefits and warrant confirmation in larger, adequately powered multicenter trials.