Molecular mechanism underline immune cell type population shift upon anti-DLL4 treatment
ABSTRACT: Molecular mechanism underline immune cell type population shift upon anti-DLL4 treatment C57BL/6 mice were injected with anti-DLL4, or an isotype control antibody as controls. Two weeks later mice were sacrificed, and thymi was harvested from 4 anti-DLL4 and 4 control animals. Total thymocytes, DN cells (CD4-CD8-) and DN1(CD4-CD8- CD44+CD25-) cells were isolated. Samples included in this data set are: 3 Thymocytes-anti-DLL4; 3 Thymocytes-isotype control; 3 DN1-anti-DLL4; 2 DN1-isotype controls; 3 DN-anti-DLL4; 3 DN-isotyoe control.
Project description:Molecular mechanism underline immune cell type population shift upon anti-DLL4 treatment C57BL/6 mice were injected with anti-DLL4, or an isotype control antibody as controls. Two weeks later mice were sacrificed, and thymi was harvested from 4 anti-DLL4 and 4 control animals. Total thymocytes, DN cells (CD4-CD8-) and DN1(CD4-CD8- CD44+CD25-) cells were isolated. Samples included in this data set are: 3 Thymocytes-anti-DLL4; 3 Thymocytes-isotype control; 3 DN1-anti-DLL4; 2 DN1-isotype controls; 3 DN-anti-DLL4; 3 DN-isotyoe control.
Project description:Molecular mechanism underline immune cell type population shift upon anti-DLL4 treatment Overall design: C57BL/6 mice were injected with anti-DLL4, or an isotype control antibody as controls. Two weeks later mice were sacrificed, and thymi was harvested from 4 anti-DLL4 and 4 control animals. Total thymocytes, DN cells (CD4-CD8-) and DN1(CD4-CD8- CD44+CD25-) cells were isolated. Samples included in this data set are: 3 Thymocytes-anti-DLL4; 3 Thymocytes-isotype control; 3 DN1-anti-DLL4; 2 DN1-isotype controls; 3 DN-anti-DLL4; 3 DN-isotyoe control.
Project description:Delta-like ligand 4 (Dll4)-Notch signaling is essential for T cell development and alternative thymic lineage decisions. How Dll4-Notch signaling affects pro-T cell fate and thymic dendritic cell (tDC) development is unknown. We found that Dll4 pharmacological blockade induces accumulation of tDCs and CD4(+)CD25(+)FoxP3(+) regulatory T cells (T(reg) cells) in the thymic cortex. Both genetic inactivation models and anti-Dll4 antibody (Ab) treatment promote de novo natural T(reg) cell expansion by a DC-dependent mechanism that requires major histocompatibility complex II expression on DCs. Anti-Dll4 treatment converts CD4(-)CD8(-)c-kit(+)CD44(+)CD25(-) (DN1) T cell progenitors to immature DCs that induce ex vivo differentiation of naive CD4(+) T cells into T(reg) cells. Induction of these tolerogenic DN1-derived tDCs and the ensuing expansion of T(reg) cells are Fms-like tyrosine kinase 3 (Flt3) independent, occur in the context of transcriptional up-regulation of PU.1, Irf-4, Irf-8, and CSF-1, genes critical for DC differentiation, and are abrogated in thymectomized mice. Anti-Dll4 treatment fully prevents type 1 diabetes (T1D) via a T(reg) cell-mediated mechanism and inhibits CD8(+) T cell pancreatic islet infiltration. Furthermore, a single injection of anti-Dll4 Ab reverses established T1D. Disease remission and recurrence are correlated with increased T(reg) cell numbers in the pancreas-draining lymph nodes. These results identify Dll4-Notch as a novel Flt3-alternative pathway important for regulating tDC-mediated T(reg) cell homeostasis and autoimmunity.
Project description:The differentiation of natural killer (NK) cells and a subpopulation of NK cells which requires an intact thymus, that is, thymic NK cells, is poorly understood. Previous in vitro studies indicate that double negative (CD4?CD8?, DN) thymocytes can develop into cells with NK cell markers, but these cells have not been well characterized. Herein, we generated and characterized NK cells differentiating from thymic DN precursors. Sorted DN1 (CD44?CD25?) CD122?NK1.1? thymocytes from Rag1(?/?) mice were adoptively transferred into Rag1(?/?)Ly5.1 congenic mice. After intrathymic injection, donor-derived cells phenotypically resembling thymic NK cells were found. To further study their differentiation, we seeded sorted DN1 CD122?)NK1.1? thymocytes on irradiated OP9 bone marrow stromal cells with IL-15, IL-7, Flt3L, and stem cell factor. NK1.1? cells emerged after 7 days. In vitro differentiated NK cells acquired markers associated with immature bone marrow-derived NK cells, but also expressed CD127, which is typically found on thymic NK cells. Furthermore, we found that in vitro cells generated from thymic precursors secreted cytokines when stimulated and degranulated on target exposure. Together, these data indicate that functional thymic NK cells can develop from a DN1 progenitor cell population.
Project description:Thymic atrophy occurs during infection being associated with apoptosis of double positive (DP) and premature exit of DP and double negative (DN) thymocytes. We observed for the first time that a significant bone marrow aplasia and a decrease in common lymphoid progenitors (CLPs) preceded thymic alterations in mice infected with Trypanosoma cruzi. In addition, depletion of the DN2 stage was previous to the DN1, indicating an alteration in the differentiation from DN1 to DN2 thymocytes. Interestingly, infected mice deficient in IL-6 expression showed higher numbers of DP and CD4+ thymocytes than wild type infected mice, while presenting similar percentages of DN1 thymocytes. Moreover, the drop in late differentiation stages of DN thymocytes was partially abrogated in comparison with wild type littermates. Thus, our results suggest that thymic atrophy involves a drop in CLPs production in bone marrow and IL-6-dependent and independent mechanisms that inhibits the differentiation of DN thymocytes.
Project description:Increasing the pool of cells at early T-cell developmental stages enhances thymopoiesis and is especially beneficial when T-cell production is compromised by radiation or aging. Within the immature double-negative (DN; CD4(-)CD8(-)) thymocyte subpopulation, the DN1 subset contains the most primitive cells including the rare early T-cell progenitors (ETPs). In the present study, a human MCL1 transgene, under the control of its endogenous promoter, resulted in enlargement of an undistorted thymus in C57/BL6 mice. Enlargement occurred in females but not males, being seen at 1 month of age and maintained during progression into adulthood as the thymus underwent involution. The small DN1 subset was expanded disproportionally (ETPs increasing from ?0.016 to 0.03% of thymocytes), while more mature thymocytes were increased proportionally (1.5-fold) along with the stroma. DN1 cells from transgenic females exhibited increased viability with maintained proliferation, and their survival in primary culture was extended. Exposure of transgenic females to ?-irradiation also revealed an expanded pool of radioresistant DN1 cells exhibiting increased viability. While the viability of DN1 cells from transgenic males was equivalent to that of their non-transgenic counterparts directly after harvest, it was enhanced in culture-suggesting that the effect of the transgene was suppressed in the in vivo environment of the male. Viability was increased in ETPs from transgenic females, but unchanged in more mature thymocytes, indicating that primitive cells were affected selectively. The MCL1 transgene thus increases the viability and pool size of primitive ETP/DN1 cells, promoting thymopoiesis and radioresistance in peripubescent females and into adulthood.
Project description:Peripheral immune regulation depends on the generation of thymic-derived regulatory T (tTreg) cells to maintain self-tolerance and to counterbalance overshooting immune responses. The expression of the Treg lineage defining transcription factor Foxp3 in developing tTreg cells depends on TCR signaling during the thymic selection process of these T cells. In this study, we surprisingly identify Foxp3+ immature thymocytes at the double-negative (DN) stage in transcription factor 7 (Tcf7)-deficient mice. These Foxp3+ cells did not express a TCR (? or ?? chains), CD3 or CD5 and therefore these cells were true DN cells. Further investigation of this phenomenon in a transgenic TCR model showed that Foxp3-expressing DN cells could not respond to TCR stimulation in vivo. These data suggest that Foxp3 expression in these DN cells occurred independently of TCR signaling. Interestingly, these Foxp3+ DN cells were located in a transition state between DN1 and DN2 (CD4-CD8-CD3-TCR-CD44highCD25low). Our results indicate that Tcf7 is involved in preventing the premature expression of Foxp3 in DN thymocytes.
Project description:The noncluster homeodomain containing gene, HOX11/TLX1 (TLX1) is detected at the breakpoint of the t(10;14)(q24;q11) chromosome translocation in patients with T cell Acute Lymphoblastic leukemia (T-ALL). This translocation results in the inappropriate expression of TLX1 in T cells. The oncogenic potential of TLX1 was demonstrated in IgHµ-TLX1Tg mice, which developed mature B cell lymphoma after a long latency period suggesting the requirement of additional mutations to initiate malignancy. To determine whether dysregulation of genes involved in the DNA damage response contributed to tumor progression, we crossed IgHµ-TLX1Tg mice with PrkdcScid/Scid mice; To identify the molecular pathways dysregulated in the earliest stages of TLX1-induced transformation, we used Affimetrix microarrays to compare gene expression profiling of premaliganant thymocytes (6~8 weeks old): DN1, DN2 and DN3 stages from HOX11 transgenic PrkdcScid/Scid (HOXSCID) mice with the same stage thymocytes from the sex and age matched control PrkdcScid/Scid (SCID) mice. Expression analysis of IgH-TLX1TgPrkdcScid/Scid thymocytes revealed dysregulated expression of cell cycle, apoptotic, mitotic spindle and anaphase-promoting complex genes in double negative (DN) 2 and DN3 stage thymocytes. Moreover, DN1, DN2 and DN3 TLX1-expressing thymocytes showed downregulated expression of ribosomal and mitochondria ribosomal protein genes. Four groups of double mutant IgH-HOX11TgPrkdcScid/Scid mice and four groups of control PrkdcScid/Scid mice were sacrificed at the age of 6~8 weeks and the fresh thymocytes were FACS sorted by markers CD25 and CD44 to DN1, DN2 and DN3 stages. To minimize the sample variability caused by individual differences among animals, about 2 ~5 the same phenotype, stage and sex thymocytes were pooled (total 104 ~ 105 cells) and used as one sample each for RNA extraction and hybridization on Affymetrix microarrays.
Project description:The reconstitution of the T-cell repertoire and quantity is a major challenge in the clinical management of HIV infection/AIDS, cancer, and aging-associated diseases. We previously showed that autologous bone marrow transfusion (BMT) via the hepatic portal vein could effectively restore CD4<sup>+</sup> T-cell count in AIDS patients also suffering from decompensated liver cirrhosis. In the current study, we characterized T-cell reconstitution in a mouse model of liver fibrosis induced by CCl<sub>4</sub> and found that T-cell reconstitution after BMT via hepatic portal vein was also greatly enhanced. The expression of Dll4 (Delta-like 4), which plays an important role in T-cell progenitor expansion, was elevated in hepatocytes of fibrotic livers when compared to normal livers. This upregulation of Dll4 expression was found to be induced by TNF? in an NF?B-dependent manner. Liver fibroblasts transfected with Dll4 (LF-Dll4) also gained the capacity to promote T-cell lineage development from hematopoietic stem cells (HSCs), resulting in the generation of DN2 (CD4 and CD8 DN 2) and DN3 T-cell progenitors in vitro, which underwent a normal maturation program when adoptively transferred into Rag-2 deficient hosts. We also demonstrated a pivotal role of SDF-1 produced by primary liver fibroblasts (primary LF) in T-lineage differentiation from HSCs. These results suggest that Dll4 and SDF-1 in fibrotic liver microenvironment could promote extrathymic T-cell lineage development. These results expand our knowledge of T-cell development and reconstitution under pathological conditions.
Project description:Signaling through the Notch pathway plays an essential role in inducing T-lineage commitment and promoting the maturation of immature thymocytes. Using an in vitro culture system, we show that 2 different classes of Notch ligands, Jagged1 or Delta1, transmit distinct signals to T-cell progenitors. OP9 stromal cells expressing either Jagged1 or Delta1 inhibit the differentiation of DN1 thymocytes into the B-cell lineage, but only the Delta1-expressing stromal cells promote the proliferation and maturation of T-cell progenitors through the early double-negative (DN) stages of thymocyte development. Whereas the majority of bone marrow-derived stem cells do not respond to Jagged1 signals, T-cell progenitors respond to Jagged1 signals during a brief window of their development between the DN1 and DN3 stages of thymic development. During these stages, Jagged1 signals can influence the differentiation of immature thymocytes along the natural killer (NK) and gamma delta T-cell lineages.