Cell Biology – Immunology – Pathology

Kidney International (2005) 68, 145–154; doi:10.1111/j.1523-1755.2005.00388.x

Apatite plaque particles in inner medulla of kidneys of calcium oxalate stone formers: Osteopontin localization

ANDREW P EVAN, FREDRIC L COE, SUSAN R RITTLING, SHARON M BLEDSOE, YOUZHI SHAO, JAMES E LINGEMAN and ELAINE M WORCESTER

Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana; Nephrology Section, University of Chicago, Chicago, Illinois; Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey; Department of Histology, Jinzhou Medical College, Jinzhou, Liaoning, People's Republic of China; and Methodist Hospital Institute for Kidney Stone Disease, Indianapolis, Indiana

Correspondence: Andrew P. Evan, Department of Anatomy & Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 5055, Indianapolis, IN 46220. E-mail: evan@anatomy.iupui.edu

Received 10 November 2004; Revised 17 January 2005; Re-revised 2 February 2005; Accepted 15 February 2005.

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Abstract

Apatite plaque particles in inner medulla of kidneys of calcium oxalate stone formers: Osteopontin localization.

Background

 

We have previously shown that interstitial plaque particles appear first in the basement membranes of thin loops of Henle and then in the interstitial space. However, it is not known if the plaque in the basement membrane of thin loops of Henle is of the same or different form than the interstitial plaque. Thus our purpose here is to detail the structure of the interstitial and membrane-bound plaque and explore the relationship of plaque apatite to osteopontin, a well-known crystal-associated urine protein.

Methods

 

Deep papillary biopsy tissue was studied from all 15 calcium oxalate stone formers and four nonforming subjects that we previously reported on [Evan et al, J Clin Ivest, 2003]. Routine light and transmission electron microscopy (TEM) as well as light microscopy and TEM immunohistochemical localization of osteopontin antibody were performed on all 19 subjects.

Results

 

In the basement membrane, plaque particles are individual and appear laminated with alternating light regions of crystal and electron-dense organic layers. In the interstitium, individual particles are not abundant but are instead aggregated to form regions of attached particles and in some regions what appears to be a fusion or syncytium in which crystal islands float in an organic sea. By light microscopy immunohistochemistry, osteopontin was localized to cells of the loops of Henle and collecting ducts as well as on sites of plaque. By immunoelectron microscopy, osteopontin immunogold label was found mainly on the surfaces of apatite crystal phase, at the junction of the crystal/organic layers. A similar immunogold labeling pattern was seen in the particles forming the syncytial islands of interstitial plaque.

Conclusion

 

If indeed we accept the hypothesis that apatite plaque may be an anchored site on which calcium oxalate stones form and grow, the present work makes clear that it is unlikely that the surface of plaque presented to the final urine will be apatite crystal per se. However, our findings clearly show osteopontin is one of the crystal-associated urine proteins involved in the formation of the organic layers of the plaque particles.

Keywords:

Randall's plague, ultrastructure, loops of Henle, immunohistochemistry

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