Physiologic Replication of Human Disease with Murine Experimental Autoimmune Thyroiditis.
Muhammad I Zulfiqar, Suresh Kari, Jeffrey Flynn, Daniel Snower, Yi-Chi Kong. St John Hospital, Detroit, MI; Wayne State University, Detroit, MI; Providence Hospital, Detroit, MI
Background: Experimental autoimmune thyroiditis (EAT) is a murine model for Hashimoto's thyroiditis (HT) with characteristics of HT including mononuclear cell infiltration, destruction of thyroid follicles, autoantibody production and T cell proliferative response to thyroid autoantigens. EAT is inducible in genetically susceptible mice by immunization with mouse thyroglobulin (mTg) and adjuvant bacterial lipopolysaccharide (LPS). We devised 3 protocols to better simulate the physiology of human disease. In #1, we replaced LPS with recombinant interleukin (rIL)-1β, a cytokine induced by LPS. In #2, we modulated the immune system by depleting regulatory T cells (Tregs), while reducing the LPS dose. In #3, we injected mTg without adjuvant to mimic fluctuating thyroglobulin levels in the circulation.
Design: #1: EAT-susceptible CBA/J mice (8-12 wks) were injected with 40 µg mTg followed 3 hrs later by 10,000 IU rIL-1β (days 0, 7). Sera were obtained on day 14 and thyroids were processed on day 28. #2: Mice were depleted of Tregs by injection of CD25 mAb (days -11, -7). Mice were injected with 40 µg mTg followed 3 hrs later by 0.5 µg LPS (day 7), and mTg only (days 14, 21). #3: Tregs were depleted by CD25 mAb treatment (days -14, -10). Mice were injected with 16 doses of 40 µg mTg without adjuvant from days 0 to 24 (4X/week). Thyroids and sera were obtained on day 35. All thyroids were examined for cellular infiltration and follicular destruction. Splenocytes were cultured with mTg, and proliferation was assessed by [3H]thymidine uptake. Anti-mTg levels were quantitated by ELISA.
Results: #1: Moderate thyroiditis, T cell proliferation and anti-mTg levels were observed in all mice treated with rIL-1β. #2: Treg-depleted mice had higher thyroiditis incidence and severity, increased T cell proliferation and anti-mTg levels, compared to controls. #3: Compared to mice given repeated mTg doses only, Treg depletion led to greater thyroiditis incidence and severity, and higher anti-mTg levels.
Conclusions: EAT can be induced in susceptible mice by treatment with mTg and rIL-1β or reduced LPS. The incidence and severity increase with Treg depletion. When repeated mTg doses without adjuvant followed Treg depletion, EAT incidence and severity are also augmented. These protocols will aid the study of consequences of immunotherapy in susceptible patients or those with pre-existing autoimmune thyroid disease. (Supported by St. John Hosp.)
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 235, Wednesday Morning