Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease where CD8 T cells eliminate insulin-producing β cells in the pancreatic islets. Yet, MHC class II haplotypes confer the greatest genetic risk for the development of T1D, suggesting a critical role for CD4 T cells. Employing the non-obese diabetic (NOD) mouse model, our lab identified in the pancreatic lymph node (pLN) a stem-like β cell-specific CD8 T cell pool required to initiate and sustain disease: pLN β cell-specific stem-CD8 T cells self-renew and continuously give rise to differentiated progenies which migrate to the pancreas (PA) and eliminate β cells; the pLN stem-CD8 T cell pool is absolutely required to sustain β cell destruction. Given the importance of autoimmune stem-CD8 T cells and the association of MHC class II in T1D pathogenesis, we wanted to understand the role of CD4 T cells in autoimmune CD8 T cell stemness and differentiation.
We employed the NOD model and longitudinally assessed the phenotypic and functional characteristics of β cell-specific CD4 T cells using flow cytometry, serial transplantation, CRISPR/Cas9-mediated gene editing, and transcriptomic studies.
Our studies reveal, for the first time, how CD4 T cells drive autoimmune CD8 T cell stemness, differentiation, and pathogenicity. We find β cell-specific CD4 T cells in pLN and PA reveal two distinct populations based on their expression of TCF1, a transcription factor critical for stemness and self-renewal. Functional studies identify pLN TCF1hi CD4 T cells as stem-T cell subset needed to drive the generation and maintenance of autoimmune stem-CD8 T cells in pLN, their differentiation into β cell-destroying cytotoxic effector cells, and ultimately T1D.
A unique population of β cell-specific CD4 T cells in pLN is critical for autoimmune CD8 T cell stemness, differentiation and disease. Identifying therapeutic strategies that target autoimmune stem-CD4 T cells could emerge as powerful approaches for the treatment of T1D.
NIH grant 1F31DK145180, NIH grant R01AI173249, Juvenile Diabetes Research Foundation grant JDRF SRA-2023-1410-S-B,
Basic Autoimmunity (BA)
Ian McBain, P. Zumbo, S. Miakicheva et al.· Journal of Immunology· 0 citations
Inflammation in the pancreas drives acinar-to-ductal metaplasia (ADM), a progenitor-like state that can be hijacked by mutant Kras in the formation of pancreatic ductal adenocarcinoma. How these cell fate decisions vary according to KRAS mutation remains poorly understood. To define mutation-specific lineage reversion and tumor initiation, we implement Ptf1a-tdTomato mice and multiple KRAS mutants across several genetic, pharmacologic, and inflammatory perturbations in vivo. Whereas KRASG12D co-opts injury to enable lineage reversion, enhancer reprogramming, and tumor initiation, KRASG12R/V cannot sustain dedifferentiated and neoplastic transcriptional and epigenetic programs. Specifically, KRASG12R/V mutants fail to invoke robust EGFR, AKT, and RAC1/VAV1 signaling and to license Pou2f3 and Vav1 in chromatin, such that only constitutive AKT activation is sufficient to rescue the tumorigenic potential of KRASG12Rin vivo. As the marked heterogeneity among KRAS variants begins early in tumorigenesis, these data are crucial to deciphering mutation-specific oncogenic trajectories and directing the implementation of KRAS-directed therapeutics.
A. Grimont, David Falvo, W. Sisso et al.· Developmental Cell· 1 citation
In autoimmunity and chronic infection, both settings of persistent (self or foreign) antigen, immune responses are sustained by stem-like CD8 T cells, which self-renew and give rise to differentiated progeny. However, if and how T stemness is epigenetically encoded, which transcription factor(s) regulate the stem-T cells, and whether the stem-T cell state is disease-specific or shared across diseases, is currently not known.
We used clinically relevant models of autoimmune type 1 diabetes (T1D) and chronic infection and conducted serial T cell transplantation studies in vivo, combined with single cell paired RNA- and ATAC-sequencing on antigen-specific T cells. We developed CRISPR/Cas9-mediated gene-editing approaches in primary T cells as well as CUT&RUN studies, identifying a novel hierarchy of transcription factors regulating stem T cell identity and function.
We discovered that a small subset of stem-T cells (TSC) express lymphoid enhancer-binding factor 1 (LEF1), a member of the TCF/LEF TF family. Paired single cell transcriptomic and epigenomic analyses reveal that the LEF1+ TSC harbor a unique epigenetically encoded molecular state enriched in genes and pathways characteristic of embryonic and adult (somatic) stem cells (e.g. neural stem cells). Strikingly, we found that TSC in chronic infection harbor a LEF1+ TSC pool sharing the core stemness epigenetic and molecular program observed in autoimmune LEF1+ TSC. Loss- and gain-of-function studies in both autoimmune T1D and chronic infection confirmed the critical role of LEF1 in maintaining T cell stemness. CUT&RUN analyses provide clues as to how LEF1 instructs the epigenetically encoded program of stem-T cells.
Here we reveal novel insights into the molecular circuitries of CD8 T cell stemness and differentiation. We discover LEF1 as the master regulator defining T cell stemness and identify novel targets for therapeutic intervention.
NIH R01AI173249, JDRF SRA-2023-1410-S-B, MSKCC Basic Research Innovation Award, The Hearst Foundation
Lymphocyte Differentiation and Peripheral Maintenance (LYM)
Katrina M. Hawley, S. Miakicheva, P. Zumbo et al.· Journal of Immunology· 0 citations
