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Abstract: FR-PO208

Diabetic Condition Induces Hypertrophy and Mitotic Catastrophe in Parietal Epithelial Cells Through Cell Cycle Re-Entry

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Kawaguchi, Takahisa, Keio University, Tokyo, Japan
  • Hasegawa, Kazuhiro, Keio University, Tokyo, Japan
  • Wakino, Shu, Keio University, Tokyo, Japan
  • Itoh, Hiroshi, Keio University, Tokyo, Japan
Background

Parietal epithelial cells (PECs) have recently been reported to be involved in the pathogenesis of crescentic glomerulonephritis (GN) and focal segmental glomerulosclerosis (FSGS); however, little information is available about changes in PECs under the diabetic condition. Therefore, we performed a detailed analysis of the morphological changes of PECs in diabetic mice and in human.

Methods

Conditionally immortalized mouse PECs were exposed to 5 mmol/L glucose (LG), 30 mmol/L glucose (HG). Hypertrophy and cell cycle were assessed by flow cytometry. Apoptosis was ascertained by Annexin V/PI staining, and caspase 3/7 staining. ROS analysis was evaluated by fluorescent intensity of CM-H2DCFDA. Streptozotocin-treated mice, db/db mice were used as diabetic mouse models. In the analysis of human kidney biopsy samples, the renal histology of the patients with diabetic kidney disease (DKD) were compared with that in the patients with other diseases. Histomorphology of the renal tissue was examined by using light microscopy and transmission electron microscopy (TEM).

Results

In cultured PECs, HG induced hypertrophy and apoptosis in a dose-dependent manner as compared to LG. This effect is not through HG-induced ROS production. Flow cytometry showed that HG increased the percentage of cells in the S phase, indicating some PECs in G0/G1 phase re-entered into S phase. In TEM, PECs exhibited enlargement of cytoplasm at the ultrastructural level in all diabetic mouse models and in human DKD kidneys from early stage before the expression of CD44, which is activated PEC marker of crescentic GN and FSGS. Although rare, binuclear cells were observed in early diabetic model mice, which suggest mitotic catastrophe. PAX 8 staining revealed PEC nuclear hypertrophy in diabetic mice, whereas the cell number of PECs remained unaltered, suggesting that PECs in diabetic condition underwent DNA replication with a mitotic defect.

Conclusion

PECs in diabetic condition are in a state of dysregulation of proliferation similar to mitotic catastrophe from early stage without the expression of PEC activation marker CD44. As PECs are considered a precursor of podocytes, this injury to PECs might impair glomerular regeneration. Further studies are warranted to elucidate the potential pathological role of these morphological changes in PECs in DKD.