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Gene expression profiles of LAG-3 positive and negative regulatory T cells in human healthy donors

ABSTRACT: Regulatory T cells (Tregs) are known to exert a critical role in self tolerance. This subset of cells is also implicated in immune evasion mechanisms operated by cancer cells. In humans, it is known that Tregs are a heterogeneous population that includes different subsets of T cells with different phenotype, differentiation state and presumably exerting their suppressor activity with different modalities. We have provided data showing that a subset of human CD4+ Tregs (CD25hiFoxp3+) expressing the Lymphocytes Activation Gene 3 (LAG-3) molecule is amplified in melanoma invaded lymph nodes as compared with their tumor free counterpart, and these cells are endowed with enhanced suppressive functions (Camisaschi et al., J Immunol 2010). To gain insights into the phenotype, functional features and specificity of this population of Tregs expressing LAG-3, we performed microarrays to obtain gene expression profiles of LAG-3+ and LAG-3- Tregs.

ORGANISM(S): Homo sapiens

PROVIDER: GSE55236 | GEO | 2020/10/31

REPOSITORIES: GEO

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Project description:The mechanism of egress of mature regulatory T cells (Tregs) from the thymus to the periphery remains enigmatic, as does the nature of those factors expressed in the thymic environment. Here, we examined the fate of thymic Tregs in TNFÎ±/RelA double-knockout (TA-KO) mice, because TA-KO mice retain a Treg population in the thymus but have only a small Treg population at the periphery. Transplantation of whole TA-KO thymus to under the kidney capsule of Rag1 null mice failed to induce the production of donor-derived splenic Tregs expressing neuropilin-1 (Nrp1), which was reported to be a marker of naturally occurring Tregs, indicating that TA-KO thymic Tregs either do not leave the thymus or are lost at the periphery. We next transplanted enriched TA-KO thymic Tregs to the peripheries of TA-KO mice and traced mouse survival. Transplantation of TA-KO thymic Tregs rescued the lethality in TA-KO mice, demonstrating that TA-KO thymic Tregs remain functional at the periphery. The TA-KO thymic Treg population had highly demethylated CpG motifs in the foxp3 locus, indicating that the cells were arrested at a late-mature stage. Also, the population included a large subpopulation of Tregs expressing IL-7RÎ±, which is a possible marker of late-mature Tregs. Finally, TA-KO fetal liver chimeric mice developed an Nrp1+ splenic Treg population from TA-KO cells, suggesting that Treg arrest is caused by a lack of RelA in the thymic environment. Together, these results suggest that egress of mature Tregs from the thymus depends on RelA in the thymic environment. For the isolation of thymic Tregs, CD4+CD8Î±-CD25hi thymocytes were isolated from five 1.5- to 2-week-old TNFÎ±-KO or TA-KO mice by using a FACSAria cell sorter. For the isolation of thymic stromal cells, 10 thymi from 1.5- to 2-week-old TNFÎ±-KO or TA-KO mice were minced with scissors and treated with RPMI 1640 supplemented with 2% FCS, 0.2 mg/ml collagenase (Roche, Basel, Switzerland), 0.2 mg/ml dispase I (Roche), and 100 U/ml DNase I (Life Technologies) for 30 min with stirring. Digested thymi were centrifuged in a Percoll (GE Healthcare Bio-Sciences, Piscataway, NJ, USA) gradient (density, 1.115, 1.065, and PBS) at 1400g for 30 min. Cells in the upper layer were collected, and the CD45-EpCAM+ (thymic epithelial cells) and CD45+EpCAM- populations (enriched thymic stromal cells containing macrophages or dendritic cells) were sorted.

Project description:Introduction Immune checkpoint blockade (ICB) is a systemic therapeutic option for advanced hepatocellular carcinoma (HCC). However, low patient response rates necessitate the development of robust predictive biomarkers that identify individuals who will benefit from ICB. A 4-gene inflammatory signature, comprising CD8, PD-L1, LAG-3, and STAT1, was recently shown to be associated with a better overall response to ICB in various cancer types. Here, we examined whether tissue protein expression of CD8, PD-L1, LAG-3, and STAT1 predicts response to ICB in HCC. Methods HCC samples from 191 Asian patients, comprising resection specimens from 124 patients (ICB-naïve) and pre-treatment specimens from 67 advanced HCC patients treated with ICB (ICB-treated), were analyzed for CD8, PD-L1, LAG-3, and STAT1 tissue expression using multiplex immunohistochemistry followed by statistical and survival analyses. Results Immunohistochemical and survival analyses of ICB-naïve samples showed that high LAG-3 expression was associated with shorter median progression-free survival (mPFS) and overall survival (mOS). Analysis of ICB-treated samples revealed that high proportions of LAG-3+ and LAG-3+CD8+ cells pre-treatment were most closely associated with longer mPFS and mOS. Using a log-likelihood model, adding the total LAG-3+ cell proportion to the total CD8+ cell proportion significantly increased the predictive values for mPFS and mOS, compared with the total CD8+ cell proportion alone. Moreover, levels of CD8 and STAT1, but not PD-L1, were significantly correlated with better responses to ICB. After analyzing viral-related and non-viral HCC samples separately, only the LAG3+CD8+ cell proportion was significantly associated with responses to ICB regardless of viral status. Conclusion Immunohistochemical scoring of pre-treatment levels of LAG-3 and CD8 in the tumor microenvironment may help predict ICB benefits in HCC patients. Furthermore, immunohistochemistry-based techniques offer the advantage of being readily translatable in the clinical setting.

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Gene expression profiles of LAG-3 positive and negative regulatory T cells in human healthy donors

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