Dataset Information

DOCK8 deficiency diminishes thymic T-regulatory cell development but not thymic deletion.

ABSTRACT:

Objective

To define the effect of DOCK8 deficiency on thymic tolerance in mice.

Methods

Thymocytes from wild-type (Dock8^+/+ ) and DOCK8-deficient (Dock8^pri/pri ) mice were examined by flow cytometry. Some mice had transgenic expression of the BCL2 anti-apoptotic protein in haemopoietic cells. Some mice expressed the transgenic 3A9 T-cell receptor (TCR), which triggers thymocyte deletion in mice also expressing hen egg lysozyme under the insulin promoter.

Results

In Dock8^pr/pri mice, the proportion of thymocytes induced to acquire tolerance at the immature CCR7^- stage was normal. Deletion of strongly self-reactive CD4⁺ thymocytes occurred efficiently in Dock8^pri/pri mice in a TCR-transgenic model that requires self-antigen transfer from epithelial cells to bone marrow (BM)-derived antigen-presenting cells. Thymic Foxp3⁺ T-regulatory cells (T_REG) and Helios⁺ Foxp3^- T_REG precursors were decreased in Dock8^pri/pri mice, including when apoptosis was inhibited by BCL2 transgene expression. Dock8^pri/pri thymic T_REG expressed CD25 and CTLA-4 at normal levels. The results suggest that DOCK8 deficiency does not affect the function of BM-derived antigen-presenting cells in the thymus, the TCR self-reactivity threshold that activates tolerance mechanisms in thymocytes or the apoptotic deletion of these thymocytes. However, DOCK8 is required to prevent a subset of developing T_REG cells from undergoing cell death via a mechanism that is distinct from apoptosis.

Conclusion

DOCK8 deficiency diminishes T_REG development in the thymus without compromising thymocyte deletion.

SUBMITTER: Randall KL

PROVIDER: S-EPMC7790591 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

DOCK8 deficiency diminishes thymic T-regulatory cell development but not thymic deletion.

Randall Katrina L KL Law Hsei Di HD Ziolkowski Andrew F AF Wirasinha Rushika C RC Goodnow Christopher C CC Daley Stephen R SR

Clinical & translational immunology 20210107 1

<h4>Objective</h4>To define the effect of DOCK8 deficiency on thymic tolerance in mice.<h4>Methods</h4>Thymocytes from wild-type (<i>Dock8<sup>+/+</sup></i> ) and DOCK8-deficient (<i>Dock8<sup>pri/pri</sup></i> ) mice were examined by flow cytometry. Some mice had transgenic expression of the BCL2 anti-apoptotic protein in haemopoietic cells. Some mice expressed the transgenic 3A9 T-cell receptor (TCR), which triggers thymocyte deletion in mice also expressing hen egg lysozyme under the insulin ...[more]

PMID: 33437483

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Project description:Receptor Interacting Protein Kinase 1 (RIPK1) and caspase-8 (Casp8) jointly orchestrate apoptosis, a key mechanism for eliminating developing T cells which have autoreactive or improperly arranged T cell receptors. Mutations in the scaffolding domain of Ripk1 gene have been identified in humans with autoinflammatory diseases like Cleavage Resistant RIPK1 Induced Autoinflammatory (CRIA) and Inflammatory Bowel Disease. RIPK1 protein also contributes to conventional T cell differentiation and peripheral T cell homeostasis through its scaffolding domain in a cell death independent context. Ripk1 deficient mice do not survive beyond birth, so we have studied the function of this kinase in vivo against a backdrop Ripk3 and Casp8 deficiency which allows the mice to survive to adulthood. These studies reveal a key role for RIPK1 in mediating NK1.1 expression, including on thymic iNKT cells, which is a key requirement for thymic stage 2 to stage 3 transition as well as iNKT cell precursor development. These results are consistent with RIPK1 mediating responses to TcR engagement, which influence NK1.1 expression and iNKT cell thymic development. We also used in vivo and in vitro stimulation assays to confirm a role for both Casp8 and RIPK1 in mediating iNKT cytokine effector responses. Finally, we also noted expanded and hyperactivated iNKT follicular helper (iNKTFH) cells in both DKO (Casp8-, Ripk3- deficient) and TKO mice (Ripk1-, Casp8-, Ripk3- deficient). Thus, while RIPK1 and Casp8 jointly facilitate iNKT effector function, RIPK1 uniquely influenced thymic iNKT cell development most likely by regulating molecular responses to T cell receptor engagement. iNKT developmental and functional aberrances were not evident in mice expressing a kinase-dead version of RIPK1 (RIPK1kd), indicating that the scaffolding function of this protein exerts the critical regulation of iNKT cells. Our findings suggest that small molecule inhibitors of RIPK1 could be used to regulate iNKT cell development and effector function to alleviate autoinflammatory conditions in humans.

Dataset Information

DOCK8 deficiency diminishes thymic T-regulatory cell development but not thymic deletion.

Objective

Methods

Results

Conclusion

Publications

DOCK8 deficiency diminishes thymic T-regulatory cell development but not thymic deletion.

Similar Datasets

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