Kidney International Reports
Introduction: Previous studies using immunofluorescent methods indicate that both the cellular crescents in crescentic glomerulonephritis and the podocyte proliferation in collapsing FSGS may both originate from parietal epithelial cells, which serve as CD133 positive progenitor cells. We have previously confirmed positive CD133 staining in the cellular crescents of crescentic glomerulonephritis. However, the role of CD133 expression in highlighting the proliferative podocytes in collapsing FSGS has not been adapted to the renal pathology practice. Methods: We have identified 19 collapsing FSGS from our archive over past 10 years (out of 3942 renal biopsies, 0.5 %). The collapsing FSGS cases were either HIV positive (3/19, 16 %) or negative (16/19, 84 %). All patients were of African American descent with prominent renal failure and nephrotic proteinuria. We used immunohistochemical methods to stain the following specimen with CD133: 19 biopsies of collapsing FSGS, 24 biopsy controls from other renal diseases, and 10 negative controls from other nephrectomy specimen. The glomerular and tubular expression of CD133 between the three groups was evaluated by light microscopy. Results: Both negative controls and biopsy controls revealed positive CD133 in parietal epithelial cells without staining in the podocytes (Below, Figure 1A [normal]. and 1B [FSGS, not otherwise specified] by CD133 staining). Negative controls did not stain for CD133 in proximal tubules while biopsy controls showed focal to diffuse CD133 staining in proximal tubules. The striking finding was that all collapsing FSGS showed positive CD133 staining in the clusters of proliferative podocytes (ranging from 4.3 % to 81 % of all glomeruli in all cases), which displayed a mosaic pattern intermingled with collapsed glomerular capillary loops (Figure 1B and 1C [collapsing FSGS] by CD133 staining; proliferative podocytes indicated by arrows). In addition, proximal tubules of the collapsing group all showed diffuse and strong CD133 staining (Figure 1C, CD133 diffuse staining in proximal tubules at the left side), corresponding to high serum creatinine levels in the patients with collapsing FSGS. Conclusions: Our data indicate that the combination of distinctive mosaic CD133 staining pattern of proliferative podocyte with intermingled capillary tufts and diffuse proximal tubular expression of CD133 can support a diagnosis of collapsing FSGS. In addition, our finding using the immunohistochemical staining of CD133 in proliferative podocytes of collapsing FSGS further supports the view that both the cellular crescents from crescentic glomerulonephrits and the proliferative podocytes are derived from the same progenitor source: parietal epithelial cells.
Xiao A, Kanaan H, Li W, ZHANG P. POS-168 Mosaic Pattern of Progenitor Cell Marker CD133 Expression to Identify Podocyte Proliferation Supports Collapsing Variant of Focal Segmental Glomerulosclerosis (FSGS). Kidney International Reports. 2021 Apr 1;6(4):S68-9.