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Kidney Week

Abstract: TH-PO403

Automated Detection and Quantification of Individual Collagen Fibers Indicates Collagen Dynamics Underlying Increased Fibrotic Index in ADPKD

Session Information

Category: Genetic Diseases of the Kidneys

  • 1201 Genetic Diseases of the Kidneys: Cystic

Authors

  • Sussman, Caroline R., Mayo Foundation for Medical Education and Research, Rochester, Minnesota, United States
  • Holmes, Heather L., Mayo Foundation for Medical Education and Research, Rochester, Minnesota, United States
  • Harris, Peter C., Mayo Foundation for Medical Education and Research, Rochester, Minnesota, United States
  • Romero, Michael F., Mayo Foundation for Medical Education and Research, Rochester, Minnesota, United States
Background

Autosomal dominant polycystic kidney disease (ADPKD) is the fourth leading cause of kidney failure. While cysts are the most obvious phenotype, accumulating evidence indicates the involvement of the extracellular matrix in in the kidney and other organs. The most abundant protein in this matrix is collagen, which is encoded by 44 genes comprising supramolecular assemblies making up 28 collagen types. As such, histological methods to assess overall collagen are valuable and routinely used in ADPKD research, yet they are limited by variability and insensitivity. We used CT-FIRE software that automatically detects individual collagen fibers to determine fiber density in glomeruli and tubules in an ADPKD mouse model.

Methods

Four-month-old Pkd1RC/RC mice were compared to WT. All mice were F1 progeny from a 129/C57BL6J cross. Kidneys were fixed, cryosectioned, and stained with Sirius red. Tissue area and fibrotic index were determined using ImageJ and collagen fibers were automatically detected using CT-FIRE fiber detection software (LOCI; Madison, WI). Statistical measurements were obtained using PRISM (GraphPad Software, Inc.).

Results

Standard brightfield imaging trended toward a higher fibrotic index in Pkd1RC/RC than WT, and individual fibers showed an increase in fiber density overall in Pkd1RC/RC . Comparison of glomeruli vs tubules showed a higher density of fibers in glomeruli for both Pkd1RC/RC and WT. Fiber density did not differ in glomeruli of Pkd1RC/RC vs WT but was higher in Pkd1RC/RC tubules (see figure). There were no differences in fiber width, length, or straightness in either glomeruli or tubules between Pkd1RC/RC and WT.

Conclusion

These data demonstrate the potential of CT-FIRE software to provide more objective, higher resolution information about collagen in ADPKD. Mice used here had already developed cysts, but additional studies are needed to determine whether this approach can provide new insight into earlier-stage ADPKD.

Funding

  • NIDDK Support