Supplementary Material for: Membranoproliferative glomerulonephritis with striated ultrastructural deposits with significantly elevated fibrinogen and fibronectin on mass spectrometry analysis: A case report and literature review

Glomerular diseases with organized deposits can be classified into various etiologies. A diagnostic algorithm based on clinical and pathological findings has been proposed. However, some cases cannot be diagnosed using existing algorithms. Here, we report the case of a 77-year-old man diagnosed with membranoproliferative glomerulonephritis (MPGN) with striated ultrastructural deposits, microfilament-like substructures with straight bands arranged in parallel in the subendothelial space by two sequential renal biopsies. His examinations and clinical findings were incompatible with known glomerular diseases with organized deposits. Dialysis was initiated 10 months after the second biopsy procedure. Furthermore, we report the first mass spectrometry analysis of laser micro-dissected glomeruli with striated ultrastructural deposits, which revealed significant levels of fibrinogen and fibronectin. Immunostaining was positive for fibrinogen, fibrin, and fibronectin in the subendothelial space. These findings suggest that the deposits were composed of a fibrin-fibronectin complex, and that accumulation of these fibrin-fibronectin complexes possibly induced endothelial injury, leading to MPGN. We also reviewed the literature on the clinical and pathological characteristics of the four cases with striated ultrastructural deposits. Our investigation showed that all patients had the MPGN pattern and striated ultrastructural deposits in the subendothelial space, and all underwent hemodialysis within 3 years after renal biopsy. Clinicians should be aware of the findings of glomerulonephritis with striated ultrastructural deposits since this disease may be a new entity and has a poor prognosis.

伴有序沉积物的肾小球疾病可依据不同病因进行分类。既往已有基于临床与病理表现的诊断算法被提出，但仍有部分病例无法通过现有算法明确诊断。本文报告1例77岁男性患者，经两次连续肾活检确诊为伴条纹状超微结构沉积物的膜增生性肾小球肾炎（membranoproliferative glomerulonephritis, MPGN）：其内皮下间隙可见呈平行排列直带的微丝样亚结构。该患者的各项检查结果与临床表现在已知伴有序沉积物的肾小球疾病中均与典型表现不符。患者于第二次肾活检后10个月启动透析治疗。此外，本文首次针对伴条纹状超微结构沉积物的激光显微切割肾小球（laser micro-dissected glomeruli）开展质谱分析（mass spectrometry），检测到高水平的纤维蛋白原（fibrinogen）与纤连蛋白（fibronectin）；免疫染色（immunostaining）结果显示，内皮下间隙区域的纤维蛋白原、纤维蛋白及纤连蛋白均呈阳性表达。上述结果提示，该沉积物由纤维蛋白-纤连蛋白复合物构成，此类复合物的沉积可能诱发内皮损伤，进而导致膜增生性肾小球肾炎。本文同时回顾了4例伴条纹状超微结构沉积物病例的临床病理特征相关文献，结果显示所有病例均表现为膜增生性肾小球肾炎表型，且内皮下间隙存在条纹状超微结构沉积物，均在肾活检后3年内接受了血液透析（hemodialysis）治疗。临床医师应警惕伴条纹状超微结构沉积物的肾小球肾炎表现，该疾病可能为一种全新的疾病实体，且预后不良。