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Immunopathology of penicillamine-induced glomerular disease
Abstract:
Four patients with rheumatoid arthritis developed heavy proteinuria after five to 12 months of treatment with D-penicillamine. Light microscopy of renal biopsy samples showed minimal glomerular capillary wall thickening and mesangial matrix increase, or no departure from normal. Electron microscopy, however, revealed subepithelial electron-dense deposits, fusion of epithelial cell foot processes, and evidence of mesangial cell hyperactivity. Immunofluorescence microscopy demonstrated granular capillary wall deposits of IgG and C3. The findings were similar to those in early membranous glomerulonephritis, differences being observed however in the results of staining for the early-acting complement components C1q and C4. It is tentatively concluded that complement was activated by the classical pathway.
Insights
D-penicillamine treatment in rheumatoid arthritis patients can cause kidney damage, specifically heavy proteinuria. Renal biopsies revealed membranous glomerulonephritis-like changes, suggesting complement activation via the classical pathway.
Area of Science:
- Nephrology
- Rheumatology
- Immunology
Background:
- Rheumatoid arthritis (RA) is a chronic autoimmune disease.
- D-penicillamine is a medication used to treat RA.
- Drug-induced nephrotoxicity is a potential complication of RA treatment.
Purpose of the Study:
- To investigate the renal pathology in rheumatoid arthritis patients treated with D-penicillamine.
- To characterize the light, electron, and immunofluorescence microscopy findings in affected kidneys.
- To elucidate the mechanism of D-penicillamine-induced kidney injury.
Main Methods:
- Analysis of renal biopsy samples from four RA patients with proteinuria.
- Light microscopy (LM) for glomerular morphology.
- Electron microscopy (EM) for ultrastructural changes.
- Immunofluorescence microscopy (IFM) for immune deposits and complement components.
Main Results:
- Patients developed heavy proteinuria after D-penicillamine treatment.
- LM showed minimal glomerular changes.
- EM revealed subepithelial electron-dense deposits and foot process effacement.
- IFM demonstrated IgG and C3 deposition, indicative of membranous glomerulonephritis-like changes.
- Differential staining for C1q and C4 suggested classical complement pathway activation.
Conclusions:
- D-penicillamine can induce a nephrotic syndrome resembling membranous glomerulonephritis in RA patients.
- The findings suggest D-penicillamine-induced proteinuria is mediated by immune complex deposition and complement activation.
- Classical complement pathway activation is implicated in the pathogenesis of this D-penicillamine nephrotoxicity.