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Nephrotoxic antiserum identifies a beta 1-integrin on rat glomerular epithelial cells
Y M O'Meara1, Y Natori, A W Minto
1Evans Memorial Department of Clinical Research, University Hospital, Boston, Massachusetts 02118.
The American Journal of Physiology
|June 1, 1992
Summary
Antibodies interacting with glomerular epithelial cell (GEC) antigens may cause kidney injury. Sheep anti-rat nephrotoxic serum (NTS) binds GEC proteins, disrupting cell-matrix interactions and causing proteinuria.
Area of Science:
- Nephrology
- Immunology
- Cell Biology
Background:
- Immune-mediated glomerular injury is often linked to antibody interactions with glomerular epithelial cell (GEC) surface antigens.
- The noncomplement-fixing gamma 2-subclass of sheep anti-rat nephrotoxic serum (NTS) induces rapid proteinuria in vivo, independent of complement and neutrophils.
Purpose of the Study:
- To investigate the interaction between NTS and rat GECs in culture.
- To identify the specific GEC surface antigens targeted by NTS.
Main Methods:
- Immunofluorescence was used to detect NTS reactivity with GEC plasma membranes.
- NTS-coated wells were assessed for GEC adhesion.
- Proteins immunoprecipitated by NTS from surface-labeled GECs were analyzed.
- Western blot analysis was performed on rat glomeruli membranes.
Main Results:
- NTS demonstrated reactivity with GEC surface antigens, confirmed by immunofluorescence and GEC adhesion assays.
- NTS immunoprecipitated two proteins (135 and 118 kDa) from GECs, identified as beta 1-integrin chain of the fibronectin receptor (FnR).
- NTS inhibited GEC adhesion and spreading on extracellular matrix proteins, including laminin and collagen, similar to anti-FnR.
Conclusions:
- NTS recognizes GEC surface proteins with characteristics of alpha- and beta 1-integrins.
- These interactions disrupt GEC cell-matrix interactions, contributing to proteinuria.
- The findings elucidate a mechanism of immune-mediated glomerular injury involving integrin disruption.