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Identification of Streptococcus pyogenes proteins that bind to rabbit kidney in vitro and in vivo
I Glurich1, B Winters, B Albini
1Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214.
Abstract:
Proteins were extracted from the surface of a nephritogenic strain of Streptococcus pyogenes M12 and tested for binding to rabbit kidney using indirect immunofluorescence and enzyme-linked immunoassays. Streptococcal antigens bound in vitro in a fine linear pattern to basal laminae of glomeruli, Bowman's capsule, and tubules. Perfusion of rabbit kidney in vivo with streptococcal components resulted in focal and segmental fine granular staining of glomerular capillaries. Three streptococcal proteins (43, 31 and 9 kDa) were recovered from renal tissue that was pretreated in vitro with S. pyogenes extract. Streptococcal components bound in vitro to heparan sulfate, heparin, laminin and collagen IV but only weakly or not at all to fibronectin, bovine serum albumin or dextran sulfate. Affinity chromatography of bacterial extracts on heparin-agarose produced a 9 kDa streptococcal protein (pI 9.5) which bound to kidney basement membranes in vitro and in isolated perfused kidneys. Several additional strains of group A streptococci were found to contain the 9 kDa cationic protein. This bacterial protein, when released into the blood by the bacterium during infection, may contribute to the pathogenesis of streptococcus-associated nephritides in man.
Insights
A specific 9 kDa protein from Streptococcus pyogenes binds to kidney structures, potentially causing kidney disease. This finding aids in understanding streptococcus-associated nephritis.
Area of Science:
- Microbiology
- Immunology
- Nephrology
Background:
- Streptococcus pyogenes is associated with kidney disease.
- The mechanisms underlying streptococcus-associated nephritides are not fully understood.
Purpose of the Study:
- To identify specific streptococcal proteins involved in kidney binding.
- To elucidate the role of these proteins in the pathogenesis of nephritis.
Main Methods:
- Proteins from Streptococcus pyogenes were isolated and tested for binding to rabbit kidney tissue in vitro and in vivo.
- Techniques included indirect immunofluorescence, enzyme-linked immunoassays, and affinity chromatography.
- Binding interactions with kidney matrix components like heparan sulfate and laminin were assessed.
Main Results:
- Streptococcal antigens demonstrated binding to glomerular and tubular basal laminae.
- A 9 kDa cationic protein was identified as a key binder to kidney basement membranes.
- This 9 kDa protein was found in multiple strains of group A Streptococcus.
Conclusions:
- The 9 kDa cationic protein from Streptococcus pyogenes binds to kidney basement membranes.
- This protein may play a significant role in the development of streptococcus-associated nephritides.