DataSheet_1_Rituximab Induces Complete Remission of Proteinuria in a Patient With Minimal Change Disease and No Detectable B Cells.docx

Minimal change disease (MCD) is a common cause of nephrotic syndrome. Treatment with steroids is usually effective, but frequent relapses are therapeutic challenges. The anti-CD20 antibody rituximab has shown promising results for treatment of steroid-sensitive nephrotic syndrome. Since predictive biomarkers for treatment efficacy and the accurate rituximab dosage for effective induction of remission are unknown, measurement of CD19+ B cells in blood is often used as marker of successful B cell depletion and treatment efficacy. A male patient with relapsing MCD was successfully treated with rituximab, but developed relapse of proteinuria 1 year later, although no B cells were detectable in his blood. B and T cell populations in the patient’s blood were analyzed before and after treatment with rituximab using FACS analysis. Rituximab binding to B and T cells were measured using Alexa Fluor 647 conjugated rituximab. We identified a population of CD20+ CD19− cells in the patient’s blood, which consisted mostly of CD20+ CD3+ T cells. Despite the absence of B cells in the blood, the patient was again treated with rituximab. He developed complete remission of proteinuria and depletion of CD20+ T cells. In a control patient with relapsing MCD initial treatment with rituximab led to depletion of both CD20+ B and T cells. Rituximab induces remission of proteinuria in patients with MCD even if circulating B cells are absent. CD20+ T cells may play a role in the pathogenesis of MCD and might be a promising treatment target in patients with MCD.

微小病变肾病（Minimal change disease, MCD）是引发肾病综合征的常见病因。糖皮质激素治疗通常有效，但频繁复发仍是临床治疗难题。抗CD20单克隆抗体利妥昔单抗（rituximab）在激素敏感型肾病综合征的治疗中已展现出良好疗效。由于目前尚不明确治疗疗效的预测性生物标志物，以及可有效诱导缓解的精准利妥昔单抗给药剂量，临床常通过检测外周血中的CD19阳性B淋巴细胞（CD19+ B cells）作为B细胞成功耗竭及治疗疗效的标志物。本研究纳入1例复发性微小病变肾病男性患者，经利妥昔单抗治疗后病情缓解，但1年后出现蛋白尿复发，尽管其外周血中未检出B淋巴细胞。研究采用流式细胞术（FACS）分析了该患者利妥昔单抗治疗前后的外周血B、T淋巴细胞亚群，并使用Alexa Fluor 647标记的利妥昔单抗（Alexa Fluor 647 conjugated rituximab）检测了利妥昔单抗与B、T淋巴细胞的结合情况。结果在患者外周血中鉴定出一类CD20阳性CD19阴性细胞亚群，该亚群主要由CD20阳性CD3阳性T淋巴细胞构成。尽管患者外周血中不存在B淋巴细胞，仍再次接受了利妥昔单抗治疗，随后实现了蛋白尿完全缓解以及CD20阳性T细胞耗竭。另1例复发性微小病变肾病对照患者在初始利妥昔单抗治疗后，其CD20阳性B淋巴细胞与T淋巴细胞均出现耗竭。本研究结果表明，即使循环B淋巴细胞缺失，利妥昔单抗仍可使微小病变肾病患者实现蛋白尿缓解。CD20阳性T淋巴细胞可能在微小病变肾病的发病机制中发挥作用，或可成为微小病变肾病患者潜在的治疗靶点。