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Idd9.2 and Idd9.3 protective alleles function in CD4+ T-cells and nonlymphoid cells to prevent expansion of pathogenic islet-specific CD8+ T-cells.

Hamilton-Williams EE, Wong SB, Martinez X, Rainbow DB, Hunter KM, Wicker LS, Sherman LA - Diabetes (2010)

Bottom Line: Interestingly, the Idd9.1 region, which provides significant protection from disease, did not prevent the expansion of autoreactive CD8(+) T-cells.Idd9 protective alleles are associated with reduced expansion of IGRP-specific CD8(+) T-cells.Protective alleles in the Idd9.2 congenic subregion are required for the maximal reduction of islet-specific CD8(+) T-cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, California, USA.

ABSTRACT

Objective: Multiple type 1 diabetes susceptibility genes have now been identified in both humans and mice, yet mechanistic understanding of how they impact disease pathogenesis is still minimal. We have sought to dissect the cellular basis for how the highly protective mouse Idd9 region limits the expansion of autoreactive CD8(+) T-cells, a key cell type in destruction of the islets.

Research design and methods: We assess the endogenous CD8(+) T-cell repertoire for reactivity to the islet antigen glucose-6-phosphatase-related protein (IGRP). Through the use of adoptively transferred T-cells, bone marrow chimeras, and reconstituted severe combined immunodeficient mice, we identify the protective cell types involved.

Results: IGRP-specific CD8(+) T-cells are present at low frequency in the insulitic lesions of Idd9 mice and could not be recalled in the periphery by viral expansion. We show that Idd9 genes act extrinsically to the CD8(+) T-cell to prevent the massive expansion of pathogenic effectors near the time of disease onset that occurs in NOD mice. The subregions Idd9.2 and Idd9.3 mediated this effect. Interestingly, the Idd9.1 region, which provides significant protection from disease, did not prevent the expansion of autoreactive CD8(+) T-cells. Expression of Idd9 genes was required by both CD4(+) T-cells and a nonlymphoid cell to induce optimal tolerance.

Conclusions: Idd9 protective alleles are associated with reduced expansion of IGRP-specific CD8(+) T-cells. Intrinsic expression of protective Idd9 alleles in CD4(+) T-cells and nonlymphoid cells is required to achieve an optimal level of tolerance. Protective alleles in the Idd9.2 congenic subregion are required for the maximal reduction of islet-specific CD8(+) T-cells.

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Idd9.2 and Idd9.3 genes contribute to restored tolerance of IGRP-specific CD8+ T-cells. NOD, Idd9, Idd9.1, Idd9.2, and Idd9.3 mice (10–14 weeks of age) were infected with Vac-IGRP and 7 days later (A) IGRP-tetramer+ CD8+ T-cells were measured in the spleen. Pooled data from three experiments are shown. The median line is shown for each group. NOD (3.5%, IQR 1.9–7.0%) vs. Idd9.2 (0.8%, IQR 0.4–1.7%), P < 0.0001 (***); and NOD vs. Idd9.3 (2.0%, IQR 0.9–3.0%), P = 0.047 (*), using the Mann-Whitney test. B: Infected and naive control mice were injected with CFSEHigh IGRP206–214–loaded NOD (or B10.D2) splenocytes and CFSElow control NOD (or B10.D2) splenocytes. Killing was assessed 16 h later in the spleen by FACS. Specific killing was calculated by the formula: 100 − [(percentage of CFSEhigh/percentage of CFSElow)/Ratio naive) × 100]. Pooled data from three experiments are shown. Line depicts median value. NOD (85%, IQR 43–94%) vs. Idd9 (27%, IQR 16–43%), P = 0.0004 (***); NOD vs. Idd9.2 (36%, IQR 18–88%), P = 0.027 (*).
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Figure 3: Idd9.2 and Idd9.3 genes contribute to restored tolerance of IGRP-specific CD8+ T-cells. NOD, Idd9, Idd9.1, Idd9.2, and Idd9.3 mice (10–14 weeks of age) were infected with Vac-IGRP and 7 days later (A) IGRP-tetramer+ CD8+ T-cells were measured in the spleen. Pooled data from three experiments are shown. The median line is shown for each group. NOD (3.5%, IQR 1.9–7.0%) vs. Idd9.2 (0.8%, IQR 0.4–1.7%), P < 0.0001 (***); and NOD vs. Idd9.3 (2.0%, IQR 0.9–3.0%), P = 0.047 (*), using the Mann-Whitney test. B: Infected and naive control mice were injected with CFSEHigh IGRP206–214–loaded NOD (or B10.D2) splenocytes and CFSElow control NOD (or B10.D2) splenocytes. Killing was assessed 16 h later in the spleen by FACS. Specific killing was calculated by the formula: 100 − [(percentage of CFSEhigh/percentage of CFSElow)/Ratio naive) × 100]. Pooled data from three experiments are shown. Line depicts median value. NOD (85%, IQR 43–94%) vs. Idd9 (27%, IQR 16–43%), P = 0.0004 (***); NOD vs. Idd9.2 (36%, IQR 18–88%), P = 0.027 (*).

Mentions: The Idd9 region has been reported to contain at least three separate subregions (Idd9.1, Idd9.2, and Idd9.3, Fig. 1). Congenic strains having only one of the protective regions are each partially protected from diabetes (2,4,7). To determine which of these regions contributes to restored tolerance to islet IGRP, subcongenic mice were infected with Vac-IGRP and the frequency of IGRP-specific tetramer+ cells was assessed (Fig. 3A). As expected from the results in Fig. 2A, Idd9 mice were highly tolerant compared with NOD mice. Idd9.1 mice contained very high percentages of IGRP-specific cells (7.9%). Idd9.2 mice exhibited a greatly reduced frequency of IGRP-specific cells (0.8%) that was similar to Idd9 mice (1.1%). Idd9.3 mice showed an intermediate frequency (2.0%). Therefore, at least two genes within the Idd9 region contribute to tolerance of IGRP-specific CD8+ T-cells and these are within the Idd9.2 and Idd9.3 regions.


Idd9.2 and Idd9.3 protective alleles function in CD4+ T-cells and nonlymphoid cells to prevent expansion of pathogenic islet-specific CD8+ T-cells.

Hamilton-Williams EE, Wong SB, Martinez X, Rainbow DB, Hunter KM, Wicker LS, Sherman LA - Diabetes (2010)

Idd9.2 and Idd9.3 genes contribute to restored tolerance of IGRP-specific CD8+ T-cells. NOD, Idd9, Idd9.1, Idd9.2, and Idd9.3 mice (10–14 weeks of age) were infected with Vac-IGRP and 7 days later (A) IGRP-tetramer+ CD8+ T-cells were measured in the spleen. Pooled data from three experiments are shown. The median line is shown for each group. NOD (3.5%, IQR 1.9–7.0%) vs. Idd9.2 (0.8%, IQR 0.4–1.7%), P < 0.0001 (***); and NOD vs. Idd9.3 (2.0%, IQR 0.9–3.0%), P = 0.047 (*), using the Mann-Whitney test. B: Infected and naive control mice were injected with CFSEHigh IGRP206–214–loaded NOD (or B10.D2) splenocytes and CFSElow control NOD (or B10.D2) splenocytes. Killing was assessed 16 h later in the spleen by FACS. Specific killing was calculated by the formula: 100 − [(percentage of CFSEhigh/percentage of CFSElow)/Ratio naive) × 100]. Pooled data from three experiments are shown. Line depicts median value. NOD (85%, IQR 43–94%) vs. Idd9 (27%, IQR 16–43%), P = 0.0004 (***); NOD vs. Idd9.2 (36%, IQR 18–88%), P = 0.027 (*).
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Figure 3: Idd9.2 and Idd9.3 genes contribute to restored tolerance of IGRP-specific CD8+ T-cells. NOD, Idd9, Idd9.1, Idd9.2, and Idd9.3 mice (10–14 weeks of age) were infected with Vac-IGRP and 7 days later (A) IGRP-tetramer+ CD8+ T-cells were measured in the spleen. Pooled data from three experiments are shown. The median line is shown for each group. NOD (3.5%, IQR 1.9–7.0%) vs. Idd9.2 (0.8%, IQR 0.4–1.7%), P < 0.0001 (***); and NOD vs. Idd9.3 (2.0%, IQR 0.9–3.0%), P = 0.047 (*), using the Mann-Whitney test. B: Infected and naive control mice were injected with CFSEHigh IGRP206–214–loaded NOD (or B10.D2) splenocytes and CFSElow control NOD (or B10.D2) splenocytes. Killing was assessed 16 h later in the spleen by FACS. Specific killing was calculated by the formula: 100 − [(percentage of CFSEhigh/percentage of CFSElow)/Ratio naive) × 100]. Pooled data from three experiments are shown. Line depicts median value. NOD (85%, IQR 43–94%) vs. Idd9 (27%, IQR 16–43%), P = 0.0004 (***); NOD vs. Idd9.2 (36%, IQR 18–88%), P = 0.027 (*).
Mentions: The Idd9 region has been reported to contain at least three separate subregions (Idd9.1, Idd9.2, and Idd9.3, Fig. 1). Congenic strains having only one of the protective regions are each partially protected from diabetes (2,4,7). To determine which of these regions contributes to restored tolerance to islet IGRP, subcongenic mice were infected with Vac-IGRP and the frequency of IGRP-specific tetramer+ cells was assessed (Fig. 3A). As expected from the results in Fig. 2A, Idd9 mice were highly tolerant compared with NOD mice. Idd9.1 mice contained very high percentages of IGRP-specific cells (7.9%). Idd9.2 mice exhibited a greatly reduced frequency of IGRP-specific cells (0.8%) that was similar to Idd9 mice (1.1%). Idd9.3 mice showed an intermediate frequency (2.0%). Therefore, at least two genes within the Idd9 region contribute to tolerance of IGRP-specific CD8+ T-cells and these are within the Idd9.2 and Idd9.3 regions.

Bottom Line: Interestingly, the Idd9.1 region, which provides significant protection from disease, did not prevent the expansion of autoreactive CD8(+) T-cells.Idd9 protective alleles are associated with reduced expansion of IGRP-specific CD8(+) T-cells.Protective alleles in the Idd9.2 congenic subregion are required for the maximal reduction of islet-specific CD8(+) T-cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, California, USA.

ABSTRACT

Objective: Multiple type 1 diabetes susceptibility genes have now been identified in both humans and mice, yet mechanistic understanding of how they impact disease pathogenesis is still minimal. We have sought to dissect the cellular basis for how the highly protective mouse Idd9 region limits the expansion of autoreactive CD8(+) T-cells, a key cell type in destruction of the islets.

Research design and methods: We assess the endogenous CD8(+) T-cell repertoire for reactivity to the islet antigen glucose-6-phosphatase-related protein (IGRP). Through the use of adoptively transferred T-cells, bone marrow chimeras, and reconstituted severe combined immunodeficient mice, we identify the protective cell types involved.

Results: IGRP-specific CD8(+) T-cells are present at low frequency in the insulitic lesions of Idd9 mice and could not be recalled in the periphery by viral expansion. We show that Idd9 genes act extrinsically to the CD8(+) T-cell to prevent the massive expansion of pathogenic effectors near the time of disease onset that occurs in NOD mice. The subregions Idd9.2 and Idd9.3 mediated this effect. Interestingly, the Idd9.1 region, which provides significant protection from disease, did not prevent the expansion of autoreactive CD8(+) T-cells. Expression of Idd9 genes was required by both CD4(+) T-cells and a nonlymphoid cell to induce optimal tolerance.

Conclusions: Idd9 protective alleles are associated with reduced expansion of IGRP-specific CD8(+) T-cells. Intrinsic expression of protective Idd9 alleles in CD4(+) T-cells and nonlymphoid cells is required to achieve an optimal level of tolerance. Protective alleles in the Idd9.2 congenic subregion are required for the maximal reduction of islet-specific CD8(+) T-cells.

Show MeSH
Related in: MedlinePlus