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IgM exacerbates glomerular disease progression in complement-induced glomerulopathy.

Panzer SE, Laskowski J, Renner B, Kulik L, Ljubanovic D, Huber KM, Zhong W, Pickering MC, Holers VM, Thurman JM - Kidney Int. (2015)

Bottom Line: However, recent studies found that IgM specifically binds damaged glomeruli.Immunofluorescence microscopy demonstrated mesangial and capillary loop deposition of IgM, whereas ultrastructural analysis found IgM deposition on endothelial cells and subendothelial areas.A monoclonal natural IgM-recognizing phospholipids also bound to glomeruli in vivo and induced albuminuria.

View Article: PubMed Central - PubMed

Affiliation: Division of Nephrology, Department of Medicine, University of Wisconsin Madison, Madison, Wisconsin, USA.

ABSTRACT
Although glomerular immunoglobulin M (IgM) deposition occurs in a variety of glomerular diseases, the mechanism of deposition and its clinical significance remain controversial. Some have theorized IgM becomes passively trapped in areas of glomerulosclerosis. However, recent studies found that IgM specifically binds damaged glomeruli. Therefore, we tested whether natural IgM binds to neo-epitopes exposed after insults to the glomerulus and exacerbates disease in mice deficient in the complement regulatory protein factor H; a model of non-sclerotic and nonimmune-complex glomerular disease. Immunofluorescence microscopy demonstrated mesangial and capillary loop deposition of IgM, whereas ultrastructural analysis found IgM deposition on endothelial cells and subendothelial areas. Factor H-deficient mice lacking B cells were protected from renal damage, as evidenced by milder histologic lesions on light and electron microscopy. IgM, but not IgG, from wild-type mice bound to cultured murine mesangial cells. Furthermore, injection of purified IgM into mice lacking B cells bound within the glomeruli and induced proteinuria. A monoclonal natural IgM-recognizing phospholipids also bound to glomeruli in vivo and induced albuminuria. Thus, our results indicate specific IgM antibodies bind to glomerular epitopes and that IgM contributes to the progression of glomerular damage in this mouse model of non-sclerotic glomerular disease.

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Purified polyclonal and monoclonal IgM binds glomerular cells in vitroCultured murine mesangial cells were incubated with polyclonal IgM or seven different monoclonal IgM clones at 37°C. Following incubation cells were analyzed by flow cytometry to determine the degree of IgM binding. (a) Purified polyclonal IgM bound to cultured primary mesangial cells (Primary MC) and bound to a mesangial cell line (MES-13, panel b). (b) Two of the monoclonal IgM clones exhibited positive binding to mesangial cells (the monoclonal IgM clone C2 in green and the monoclonal IgM clone F632 in blue). (c) The remaining five monoclonal IgM clones did not demonstrate binding to mesangial cells. Isotype control is represented by the purple shaded histogram.
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Figure 5: Purified polyclonal and monoclonal IgM binds glomerular cells in vitroCultured murine mesangial cells were incubated with polyclonal IgM or seven different monoclonal IgM clones at 37°C. Following incubation cells were analyzed by flow cytometry to determine the degree of IgM binding. (a) Purified polyclonal IgM bound to cultured primary mesangial cells (Primary MC) and bound to a mesangial cell line (MES-13, panel b). (b) Two of the monoclonal IgM clones exhibited positive binding to mesangial cells (the monoclonal IgM clone C2 in green and the monoclonal IgM clone F632 in blue). (c) The remaining five monoclonal IgM clones did not demonstrate binding to mesangial cells. Isotype control is represented by the purple shaded histogram.

Mentions: Purified polyclonal murine IgM bound to primary culture of murine mesangial cells (Figure 5a) and to a murine mesangial cell line (MES-13 cells, Figure 5b) at 37°C. To characterize the binding of IgM to glomerular epitopes, we screened monoclonal natural IgM clones for their ability to bind to mesangial cells at 37°C. Two of the monoclonal IgM clones tested, C2 and F632, bound to mesangial cells (MES-13) in vitro (Figure 5b). The five other clones tested did not bind to the mesangial cells (Figure 5c). We also tested the binding of the monoclonal antibodies to mesangial cells grown in primary culture. C2 and F632 also bound to these mesangial cells, whereas the other IgM clones did not.


IgM exacerbates glomerular disease progression in complement-induced glomerulopathy.

Panzer SE, Laskowski J, Renner B, Kulik L, Ljubanovic D, Huber KM, Zhong W, Pickering MC, Holers VM, Thurman JM - Kidney Int. (2015)

Purified polyclonal and monoclonal IgM binds glomerular cells in vitroCultured murine mesangial cells were incubated with polyclonal IgM or seven different monoclonal IgM clones at 37°C. Following incubation cells were analyzed by flow cytometry to determine the degree of IgM binding. (a) Purified polyclonal IgM bound to cultured primary mesangial cells (Primary MC) and bound to a mesangial cell line (MES-13, panel b). (b) Two of the monoclonal IgM clones exhibited positive binding to mesangial cells (the monoclonal IgM clone C2 in green and the monoclonal IgM clone F632 in blue). (c) The remaining five monoclonal IgM clones did not demonstrate binding to mesangial cells. Isotype control is represented by the purple shaded histogram.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556608&req=5

Figure 5: Purified polyclonal and monoclonal IgM binds glomerular cells in vitroCultured murine mesangial cells were incubated with polyclonal IgM or seven different monoclonal IgM clones at 37°C. Following incubation cells were analyzed by flow cytometry to determine the degree of IgM binding. (a) Purified polyclonal IgM bound to cultured primary mesangial cells (Primary MC) and bound to a mesangial cell line (MES-13, panel b). (b) Two of the monoclonal IgM clones exhibited positive binding to mesangial cells (the monoclonal IgM clone C2 in green and the monoclonal IgM clone F632 in blue). (c) The remaining five monoclonal IgM clones did not demonstrate binding to mesangial cells. Isotype control is represented by the purple shaded histogram.
Mentions: Purified polyclonal murine IgM bound to primary culture of murine mesangial cells (Figure 5a) and to a murine mesangial cell line (MES-13 cells, Figure 5b) at 37°C. To characterize the binding of IgM to glomerular epitopes, we screened monoclonal natural IgM clones for their ability to bind to mesangial cells at 37°C. Two of the monoclonal IgM clones tested, C2 and F632, bound to mesangial cells (MES-13) in vitro (Figure 5b). The five other clones tested did not bind to the mesangial cells (Figure 5c). We also tested the binding of the monoclonal antibodies to mesangial cells grown in primary culture. C2 and F632 also bound to these mesangial cells, whereas the other IgM clones did not.

Bottom Line: However, recent studies found that IgM specifically binds damaged glomeruli.Immunofluorescence microscopy demonstrated mesangial and capillary loop deposition of IgM, whereas ultrastructural analysis found IgM deposition on endothelial cells and subendothelial areas.A monoclonal natural IgM-recognizing phospholipids also bound to glomeruli in vivo and induced albuminuria.

View Article: PubMed Central - PubMed

Affiliation: Division of Nephrology, Department of Medicine, University of Wisconsin Madison, Madison, Wisconsin, USA.

ABSTRACT
Although glomerular immunoglobulin M (IgM) deposition occurs in a variety of glomerular diseases, the mechanism of deposition and its clinical significance remain controversial. Some have theorized IgM becomes passively trapped in areas of glomerulosclerosis. However, recent studies found that IgM specifically binds damaged glomeruli. Therefore, we tested whether natural IgM binds to neo-epitopes exposed after insults to the glomerulus and exacerbates disease in mice deficient in the complement regulatory protein factor H; a model of non-sclerotic and nonimmune-complex glomerular disease. Immunofluorescence microscopy demonstrated mesangial and capillary loop deposition of IgM, whereas ultrastructural analysis found IgM deposition on endothelial cells and subendothelial areas. Factor H-deficient mice lacking B cells were protected from renal damage, as evidenced by milder histologic lesions on light and electron microscopy. IgM, but not IgG, from wild-type mice bound to cultured murine mesangial cells. Furthermore, injection of purified IgM into mice lacking B cells bound within the glomeruli and induced proteinuria. A monoclonal natural IgM-recognizing phospholipids also bound to glomeruli in vivo and induced albuminuria. Thus, our results indicate specific IgM antibodies bind to glomerular epitopes and that IgM contributes to the progression of glomerular damage in this mouse model of non-sclerotic glomerular disease.

Show MeSH
Related in: MedlinePlus