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De novo CD44 expression by proliferating mesangial cells in rat anti-Thy-1 nephritis
D J Nikolic-Paterson1, Z Jun, G H Tesch
1Department of Nephrology, Monash Medical Centre, Clayton, Victoria, Australia.
Insights
This study reveals that CD44 and hyaluronan interactions are crucial for mesangial cell proliferation during rat anti-Thy-1 nephritis. These findings highlight a key mechanism in kidney disease progression.
Area of Science:
- Nephrology
- Cell Biology
- Immunology
Background:
- CD44 is a cell-surface receptor for hyaluronan, mediating cell-matrix interactions vital for cellular functions like migration.
- Mesangial proliferative response is a key feature in various kidney diseases, including anti-Thy-1 nephritis.
Purpose of the Study:
- To investigate the expression and role of CD44 and hyaluronan in the mesangial proliferative response in rat anti-Thy-1 nephritis.
- To elucidate the functional interaction of the CD44/hyaluronan receptor-ligand pair in this experimental nephritis model.
Main Methods:
- Immunohistochemistry to detect CD44 and hyaluronan expression in normal and nephritic rat kidneys.
- Double-staining with proliferating cell nuclear antigen (PCNA) to assess mesangial cell proliferation.
- In vitro studies using rat mesangial cells to analyze CD44 expression and hyaluronan-dependent aggregation.
Main Results:
- CD44 expression was observed in normal kidney structures and significantly increased in glomerular macrophages during nephritis.
- De novo CD44 expression by mesangial cells correlated with their proliferation phase.
- Hyaluronan deposition was detected in areas with proliferating CD44+ cells, indicating a functional interaction.
- In vitro, rat mesangial cells expressed CD44, and anti-CD44 antibody inhibited hyaluronan-dependent cell aggregation.
Conclusions:
- The CD44/hyaluronan receptor-ligand pair plays a significant role in mediating mesangial cell proliferation during rat anti-Thy-1 nephritis.
- These findings suggest that targeting the CD44/hyaluronan pathway could be a therapeutic strategy for proliferative glomerulonephritis.
Abstract:
CD44 is the major cell-surface receptor for hyaluronan, and cell-matrix interactions mediated by the CD44/hyaluronan receptor-ligand pair are involved in a variety of cellular functions, including cell migration. The aim of the study presented here was to examine the expression of CD44 and hyaluronan in the mesangial proliferative response in rat anti-Thy-1 nephritis. In normal rat kidney, CD44 is expressed by medullary tubules, some distal tubules and thick ascending limbs of Henle, dendritic-like cells around Bowman's capsule, and some interstitial cells. However, only occasional CD44+ cells were found within the glomerular tuft. In experimental nephritis, there was an early glomerular influx of CD44+ macrophages, which peaked on Day 4 after anti-Thy-1 antibody injection. A striking finding was de novo CD44 expression by mesangial cells. This CD44 expression was restricted to the transient period of mesangial cell proliferation as shown by double-staining with an antibody against the proliferating cell nuclear antigen. Immunohistochemistry staining also demonstrated hyaluronan deposition within segmental areas of proliferating CD44+ cells, suggesting a functional interaction between the CD44/hyaluronan receptor-ligand pair during mesangial cell proliferation. In vitro, rat mesangial cells were shown to express mRNA and protein for the 90-kd isoform of CD44. In addition, hyaluronan-dependent aggregation of CD44+ mesangial cells was specifically inhibited by an anti-CD44 antibody, demonstrating a functional interaction between hyaluronan and the CD44 expressed on the surface of rat mesangial cells. In conclusion, these data suggest that cell-matrix interactions mediated by the CD44/hyaluronan receptor-ligand pair are involved in mesangial cell proliferation in rat anti-Thy-1 nephritis.