Mitochondrial DNA deletion-dependent podocyte injuries in Mito-miceΔ, a murine model of mitochondrial disease.

Focal segmental glomerulosclerosis (FSGS) is a major renal complication of human mitochondrial disease. However, its pathogenesis has not been fully explained. In this study, we focused on the glomerular injury of mito-miceΔ and investigated the pathogenesis of their renal involvement. We analyzed biochemical data and histology in mito-miceΔ. The proteinuria began to show in some mito-miceΔ with around 80% of mitochondrial DNA deletion, then proteinuria developed dependent with higher mitochondrial DNA deletion, more than 90% deletion. Mito-miceΔ with proteinuria histologically revealed FSGS. Immunohistochemistry demonstrated extensive distal tubular casts due to abundant glomerular proteinuria. Additionally, the loss of podocyte-related protein and podocyte's number were found. Therefore, the podocyte injuries and its depletion had a temporal relationship with the development of proteinuria. This study suggested mitochondrial DNA deletion-dependent podocyte injuries as the pathogenesis of renal involvement in mito-miceΔ. The podocytes are the main target of mitochondrial dysfunction originated from the accumulation of mitochondrial DNA abnormality in the kidney.

A case report of progressive multifocal leukoencephalopathy during steroid treatment for ANCA-associated renal vasculitis.

CASE REPORT: an 80-year-old woman presented with rapidly progressive glomerulonephritis and was admitted to our hospital. Myeloperoxidase-specific antineutrophil cytoplasmic antibody (MPO-ANCA) was positive. We diagnosed ANCA-associated renal vasculitis (ANCA-RV). Treatment was initiated with intravenous methylprednisolone pulse therapy, followed by prednisolone (PSL) at 30 mg/day. We gradually reduced the PSL dose to 7.5 mg/day over 6 months. At that time, the patient developed disturbances of consciousness which progressed subacutely. MRI revealed regions of patchy white matter with an increased signal on T2-weighted, fluid attenuated inversion recovery (FLAIR) sequences and diffusion-weighted sequences. JC virus DNA was detected in the cerebrospinal fluid (CSF) by polymerase chain reaction (PCR), leading to a diagnosis of progressive multifocal leukoencephalopathy (PML). PML is a rare infectious demyelinating disease of the central nervous system caused by JC virus infection, occurring in highly immunosuppressed individuals such as HIV-infected patients and patients using some biological agents, and having a very poor prognosis. In the present case, PML may have been associated with steroid use, although there are very few case reports of PML in patients taking only steroids. We report progressive multifocal leukoencephalopathy during steroid treatment of ANCA-RV. When patients show progressive disturbance of consciousness during treatment for ANCA-RV, we need to take PML into consideration for differential diagnosis.