Membranoproliferative glomerulonephritis
OK, so a bit complex, strap in. All types of the disease involve deposits at the intraglomerular mesangium and glomerular mesangial cell growth, often along with basement membrane thickening due to inflammation. There are now two types of membranoproliferative glomerulonephritis:
PAS-stained kidney biopsy showing an enlarged, lobulated glomerulus with increased mesangial cells and matrix, the typical light-microscopy pattern of membranoproliferative glomerulonephritis.
Image: “Membranoproliferative glomerulonephritis - very high mag” by Nephron, CC BY-SA 3.0, via Wikimedia Commons.
- Immunoglobulin-mediated type
- Complement mediated type
The immunoglobulin type is associated with immune complex disease, such as systemic lupus, chronic infections (such as HBV and HCV) and others. This form sees the deposition of both IgG and complement elements under and above the basement membrane.
Meanwhile, the complement mediated form of the disease can be associated with genetic causes, which lead to deregulation of the complement system (specifically, deregulation of C3 convertase, meaning C3 is converted to C3a and C3b readily, and are deposited under the basement membrane.
Clinical manifestation is that of nephrotic syndrome with proteinuria. A low serum complement level can be found in the complement form, while this is only occasionally decreased in the immunoglobulin form. Diagnosis is generally via biopsy with immunohistochemistry.
Treatment is difficult, there are few treatments that have proved clinically effective.