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Local macrophage proliferation in human glomerulonephritis
N Yang1, N M Isbel, D J Nikolic-Paterson
1Department of Nephrology, Monash Medical Centre, Clayton, Victoria, Australia.
Background:
Local macrophage proliferation has been described in several animal models of glomerulonephritis (GN), but its significance in human disease is unknown.
Methods:
Double immunostaining for CD68 and the proliferating cell nuclear antigen (PCNA) was used to identify macrophage proliferation in 84 biopsies from a variety of glomerulonephridities.
Results:
A small resident population of glomerular and interstitial CD68+ macrophages was identified in normal human kidney, of which only 1 to 2% showed evidence of proliferation on the basis of PCNA expression. A mild macrophage infiltrate, with only occasional proliferating macrophages, was seen in the less aggressive forms of GN (minimal change disease, non-IgA mesangioproliferative GN and IgA nephropathy). This was in sharp contrast to the more aggressive forms of disease (lupus class IV, vasculitis-associated GN, crescentic GN and mesangiocapillary proliferative GN), in which the prominent macrophage infiltrates contained many proliferating macrophages, accounting for 28 to 47% of the total macrophage population. Macrophage proliferation was largely restricted to areas of severe tissue damage (glomerular segmental proliferative lesions, crescents and foci of tubulointerstitial damage), suggesting that local proliferation is a mechanism for amplifying macrophage-mediated injury. Glomerular and interstitial macrophage proliferation gave a significant correlation with loss of renal function (P < 0.0001) and histologic lesions (P < 0.0001), but not with proteinuria. Interstitial T-cell proliferation also gave a significant correlation with loss of renal function and histologic damage, even though proliferation within the T-cell population was much lower than in the macrophage population.
Conclusions:
This study demonstrates that macrophage proliferation is a feature of the more aggressive forms of human GN. Local proliferation may be an important mechanism for amplifying macrophage-mediated renal injury. In addition, the degree of local macrophage proliferation may be a useful diagnostic and prognostic indicator for human GN.
Insights
Macrophage proliferation is significant in aggressive human glomerulonephritis (GN), correlating with kidney damage. This local proliferation may amplify injury and serve as a prognostic indicator for GN.
Area of Science:
- Nephrology
- Immunology
- Pathology
Background:
- Local macrophage proliferation is observed in animal models of glomerulonephritis (GN).
- The significance of macrophage proliferation in human GN remains largely unknown.
- Understanding macrophage roles is crucial for diagnosing and treating kidney diseases.
Purpose of the Study:
- To investigate the presence and significance of macrophage proliferation in human GN biopsies.
- To determine if local macrophage proliferation correlates with disease severity and renal function loss.
Main Methods:
- Analyzed 84 human kidney biopsies from various forms of GN.
- Utilized double immunostaining for CD68 (macrophage marker) and PCNA (proliferation marker).
- Correlated macrophage proliferation with histologic lesions and loss of renal function.
Main Results:
- Macrophage proliferation was minimal in normal kidneys and less aggressive GN forms.
- Aggressive GN forms showed significant macrophage proliferation (28-47% of macrophages).
- Macrophage proliferation correlated strongly with renal function loss and tissue damage, but not proteinuria.
Conclusions:
- Macrophage proliferation is a key feature of aggressive human GN.
- Local macrophage proliferation amplifies kidney injury and may serve as a diagnostic/prognostic marker.
- Further research into macrophage-driven injury mechanisms is warranted.