T Cell Infiltration of the Adrenal Gland in Non-Obese Diabetic (NOD) and Transgenic NOD Mice - Possible Model for Autoimmune Adrenal Insufficiency

Presentation Number: MON 382
Date of Presentation: April 3rd, 2017

Elizabeth Anne Regan*1, Michael Weaver2, Robin S Lindsay3, Kira Rubtsova2, Rachel S Friedman2, Maki Nakayama4, James D. Crapo2 and Philippa Marrack2
1National Jewish Health, Denver, CO, 2National Jewish Health, 3University of Colorado School of Medicine, 4Barbara Davis Center for Childhood Diabetes, University of Colorado School of Medicine

Abstract

Introduction: More than 70% of primary adrenal insufficiency is attributed to autoimmune disease. This process has been shown to proceed slowly over a period of years in patients who are “at risk” from autoimmune conditions. A preventative treatment to protect the adrenal from autoimmune destruction would be desirable but the ability to test treatments is limited by the lack of an animal model of disease. The non-obese diabetic (NOD) mouse has been studied in Type 1 diabetes (T1D) and shown to model the autoimmune destruction of the islet b cells . The NOD mouse has also been found to have adrenal infiltration without apparent impairment of corticosterone production 1

 Hypothesis: The non-obese diabetic mouse will show adrenal infiltration and impaired function consistent with autoimmune attack

 Methods: Routine hematoxylin and eosin (H+E) histology was performed on adrenal glands from NOD mice that had not developed diabetes, from ages 10 – 39 weeks. We also analyzed NOD mice that lack the insulin epitope required for T1D (NOD insTG)2. Immunohistochemistry was performed on tissue sections for aldosterone. Adrenals were digested and white cell populations investigated using flow cytometry in similar-aged C57B6 control mice and NOD mice. NOD insTG mice at 8 weeks of age were treated with cyclophosphamide3 for 6 weeks to induce adrenalitis and adrenals were harvested. Results: NOD mice and transgenic diabetes resistant NOD mice showed distinct areas of immune cell infiltration on H+E histology that corresponded to regions of reduced aldosterone secretion in the zona glomerulosa. The extent of cellular infiltration increased in older mice. Flow cytometry demonstrated increased CD4+ (43% vs 18%) and CD8+ (24% vs 18%) T cell counts in the NOD mice compared to C57B6 mice. Cyclophosphamide treated mice had twice as large areas of WBC infiltration compared to untreated mice.

Interpretation: The NOD mouse has been shown to model the autoimmune process in T1D with islet-infiltrating CD4+ and CD8+ cells driving reduced insulin production and autoimmune destruction of the islet cells. We see evidence of a similar process of T cell infiltration in the adrenal glands of NOD mice that have not developed diabetes, and in a transgenic NOD mouse protected from diabetes. We were able to induce increased WBC infiltration in NOD insTG mice with cyclophosphamide. In addition to cellular infiltration, these regions show reduced synthetic activity for aldosterone in the adrenal gland. The NOD mouse or the NOD insTG may be a satisfactory model to understand the mechanism of autoimmune attack on the adrenal gland and provide an opportunity for therapeutic drug trials.

 

Nothing to Disclose: EAR, MW, RSL, KR, RSF, MN, JDC, PM