Abstract: TH-PO214

Podocytes Contact with the Mesangial Cells at the Mesangial Interposition in a Case of Human Lupus Nephritis: Three-Dimensional Observation by Serial Block-Face Scanning Electron Microscopy

Session Information

Category: Nephrology Education

  • 1302 Fellows and Residents Case Reports

Authors

  • Takaki, Takashi, Showa University, Tokyo, Japan
  • Ohno, Nobuhiko, Jichi Medical University, Shimotsuke-shi, Japan
  • Saitoh, Sei, National Institute for Physiological Sciences, Okazaki, Japan
  • Nagai, Masaaki, Narita Memorial Hospital, Toyohashi-shi, Japan
  • Joh, Kensuke, Tohoku University Graduate School of Medicine, Sendai-city, Japan
Background

We employed serial block-face scanning electron microscopy (SBF-SEM) to examine the three-dimensional relationships among the cells and extracellular matrix in a case of human lupus nephritis.

Methods

A 25 year-old female, who presented nephrotic syndrome, microscopic hematuria 10-20/hpf, and hypocomplementemia with C3 47 mg/dl and C4 4 mg/dl. Anti-nuclear antigen titer and anti ds-DNA titer were x640 and 191 mg/dl, respectively. Renal biopsy revealed membranoproliferative glomerulonephritis like lesion of lupus nephritis, Class IV A/C in light microscopy. The detail of ultrastructural morphology was almost similar to that of TEM excepting a thicker staining on the nuclear membrane and thinner staining of immune deposits. Using SBF-SEM, we followed the localization of the cytoplasmic processes of the podocyte, which invaded into the lamina densa of the glomerular basement membrane (GBM) and penetrated finally into the mesangial matrix. On the other hand, mesangial interposition was seen of varying length beneath the lamina densa of the GBM along the glomerular capillary loop. The mesangial cells, which were recognized in the extended mesangial matrix as having dense patch on the cytoplasmic membrane, showed a proliferative change. We followed the cytoplasmic process of the podocyte penetrating into the mesangial matrix and have succeeded to find a manifestation of direct cytoplasmic contact of the podocytes with the cytoplasm of the mesangial cells (Figure).

Conclusion

Since a direct contact between podocytes and mesangial cells was found, it is easier to understand an effect of podocytes on the mesangial cells by assuming an intercellular signaling communication, which may result in a proliferation of the mesangial cells and an overproduction of the extracellular matrix. This finding provides a new insight on a mechanism of a progression of glomerular sclerosis via podocyte-mesangial interaction.

Funding

  • Government Support - Non-U.S.