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Kidney Week

Abstract: TH-PO944

Towards a Standardized Histological Identification of CINAC Patients: Methods and Pitfalls in Microscopic Diagnosis

Session Information

Category: CKD (Non-Dialysis)

  • 1903 CKD (Non-Dialysis): Mechanisms

Authors

  • Schreurs, Gerd, University of Antwerp, Antwerp, Belgium
  • Nast, Cynthia C., Cedars-Sinai Medical Center, Los Angeles, California, United States
  • Jayasumana, Channa, Faculty of Medicine, Anuradhapura, Sri Lanka
  • Roels, Frank, Ghent University, Gent, Belgium
  • Herath, Chulani Aravinda, Sri Jayawardenepura General Hospital, Colombo 5, Sri Lanka
  • Gowrishankar, Swarnalata, Apollo Hospitals, HYDERABAD, India
  • Mousson, Christiane I., University Hospital Dijon, Dijon, France
  • Dassanayake, Rajeewa Thilanka, General hospital Polonnaruwa Sri Lanka, Polonnaruwa, Sri Lanka
  • Orantes, Carlos Manuel, National Direction of Non-communicable diseases of Ministry of Health of El Salvador, San Salvador, El Salvador
  • D'Haese, Patrick C., University of Antwerp, Antwerp, Belgium
  • De Broe, Marc E., University of Antwerp, Antwerp, Belgium
  • Vervaet, Benjamin Arthur, University of Antwerp, Antwerp, Belgium
Background

Patients with Chronic Interstitial Nephritis in Agricultural Communities (CINAC) demonstrate previously unidentified enlarged granules in the proximal tubular (PT) epithelium, first discovered and easily recognizable on Jones’ methenamine silver stained renal biopsies and by autofluorescence. The aim is to 1) identify the nature of the granules, 2) provide a standardized Jones staining protocol for granule identification, 3) evaluate autofluorescence as a rapid diagnostic method and 4) assess EM analysis.

Methods

Formalin fixed deparaffinized renal tissue sections (4µm) of Sri Lanka and El Salvador CINAC patients and patients with proteinuric pathologies were subjected to Jones staining protocols with varying silver solution incubation times. Autofluorescence of 4µm sections was imaged (2-7 secs shutter time), followed by standardized Jones staining of the same tissue section. Immunofluorescence microscopy was performed for the mitochondrial marker COX6c and for lysosomal markers LAMP1 and Cathepsin B. EM of CINAC and proteinuric renal biopsies was performed.

Results

Jones stain invariably revealed the specific PT granules only when the incubation in silver-solution was >90 min, surpassing the time (60 min) needed to visualize basement membranes. CINAC biopsies showed PT autofluorescent granules in a pattern similar to the argyrophylic granules, with nearly all autofluorescent granules also being argyrophylic. Most autofluorescent granules were identified as lysosomes with LAMP1 and Cathepsin B. In proteinuric patients, PT argyrophylic and autofluorescent granules may occur. However, on EM, proteinuric lysosomes were round, and did not contain dispersed electron dense aggregates as obseved in CINAC patients.

Conclusion

PT CINAC granules are lysosomes, identifiable by Jones staining with prolonged silver incubation and more rapidly by autofluorescence. EM of PT lysosomes can identify suspected CINAC patients, with or without proteinuria.