IL-4 and IL-13 Guide Early Thymic Progenitors To Mature toward Dendritic Cells

Tonic type 2 immunity is a critical tissue checkpoint controlling autoimmunity in the skin

Immunoregulatory mechanisms established in the lymphoid organs are vital for preventing autoimmunity. However, the presence of similar mechanisms in non-lymphoid tissues remains unclear. Through transcriptomic and lipidomic analyses, we find a negative association between psoriasis and fatty acid metabolism, as well as Th2 signature. Homeostatic expression of liver X receptor (LXR) and peroxisome proliferator-activated receptor gamma (PPARγ) is essential for maintaining fatty acid metabolism and for conferring resistance to psoriasis in mice. Perturbation of signal transducer and activator of transcription 6 (STAT6) diminishes the homeostatic levels of LXR and PPARγ. Furthermore, mice lacking STAT6, interleukin 4 receptor alpha (IL-4Rα), or IL-13, but not IL-4, exhibit increased susceptibility to psoriasis. Under steady state, innate lymphoid cells (ILCs) are the primary producers of IL-13. In human skin, inhibiting tonic type 2 immunity exacerbates psoriasis-like inflammation and IL-17A, while activating LXR or PPARγ inhibits them. Hence, we propose that tonic type 2 immunity, driven by IL-13-producing ILCs, represents a crucial tissue checkpoint that represses autoimmunity and maintains lipid homeostasis in the skin.

Redefining the Foreign Antigen and Self-Driven Memory CD4+ T-Cell Compartments via Transcriptomic, Phenotypic, and Functional Analyses

Under steady-state conditions, conventional CD4⁺ T lymphocytes are classically divided into naïve (CD44^lo CD62L^hi) and memory (CD44^hi CD62L^lo) cell compartments. While the latter population is presumed to comprise a mixture of distinct subpopulations of explicit foreign antigen (Ag)-specific “authentic” memory and foreign Ag-independent memory-phenotype (MP) cells, phenotypic markers differentially expressed in these two cell types have yet to be identified. Moreover, while MP cells themselves have been previously described as heterogeneous, it is unknown whether they consist of distinct subsets defined by marker expression. In this study, we demonstrate using combined single-cell RNA sequencing and flow cytometric approaches that self-driven MP CD4⁺ T lymphocytes are divided into CD127^hi Sca1^lo, CD127^hi Sca1^hi, CD127^lo Sca1^hi, and CD127^lo Sca1^lo subpopulations that are Bcl2^lo, while foreign Ag-specific memory cells are CD127^hi Sca1^hi Bcl2^hi. We further show that among the four MP subsets, CD127^hi Sca1^hi lymphocytes represent the most mature and cell division-experienced subpopulation derived from peripheral naïve precursors. Finally, we provide evidence arguing that this MP subpopulation exerts the highest responsiveness to Th1-differentiating cytokines and can induce colitis. Together, our findings define MP CD4⁺ T lymphocytes as a unique, self-driven population consisting of distinct subsets that differ from conventional foreign Ag-specific memory cells in marker expression and establish functional relevance for the mature subset of CD127^hi Sca1^hi MP cells.

IL-13 in dermal type-2 dendritic cell specialization: from function to therapeutic targeting

Skin functions as a barrier protecting the host against physical, thermal, chemical changes and microbial insults. The skin is populated by several immune cell types which are crucial to host defence and to maintain self-tolerance as well as equilibrium with beneficial microbiota. Conventional dendritic cells (cDCs) are antigen-presenting cells that patrol the skin and all other non-lymphoid tissues for self or foreign antigens, then migrate to draining lymph nodes to initiate T cell responses. This review article describes recent developments on skin cDC specialization, focusing on the role of IL-13, a cytokine essential to allergic immune responses that is also secreted at steady state by type-2 innate lymphoid cells in healthy skin and is required for dermal cDC differentiation. Furthermore, we contextualize how different therapeutics that block IL-13 signaling and were recently approved for the treatment of atopic dermatitis might affect cDCs in human skin. This article is protected by copyright. All rights reserved.

In Silico Integration of Transcriptome and Interactome Predicts an ETP-ALL-Specific Transcriptional Footprint that Decodes its Developmental Propensity

Early T precursor acute lymphoblastic leukemia (ETP-ALL) exhibits poor clinical outcomes and high relapse rates following conventional chemotherapeutic protocols. Extensive developmental flexibility of the multipotent ETP-ALL blasts with considerable intra-population heterogeneity in terms of immunophenotype and prognostic parameters might be a target for novel therapeutic interventions. Using a public gene expression dataset (GSE28703) from NCBI GEO DataSets with 12 ETP-ALL and 40 non-ETP-ALL samples, such heterogeneity was found to be reflected in their transcriptome as well. Hub genes were identified from the STRING-derived functional interaction network of genes showing differential expression between ETP-ALL and non-ETP-ALL as well as variable expression across ETP-ALL. Nine genes (KIT, HGF, NT5E, PROM1, CD33, ANPEP, CDH2, IL1B, and CXCL2) among the hubs were further validated as possible diagnostic ETP-ALL markers using another gene expression dataset (GSE78132) with 17 ETP-ALL and 27 non-ETP-ALL samples. Linear dimensionality reduction analysis with the expression levels of the hub genes in ETP-ALL revealed their divergent inclinations towards different hematopoietic lineages, proposing them as novel indicators of lineage specification in the incompletely differentiated ETP-ALL blasts. This further led to the formulation of a personalized lineage score calculation algorithm, which uncovered a considerable B-lineage-bias in a substantial fraction of ETP-ALL subjects from the GSE28703 and GSE78132 cohorts. In addition, STRING-derived physical interactome of the potential biomarkers displayed complete segregation of the B-lineage-skewed markers from other lineage-associated factors, highlighting their distinct functionality and possible druggability in ETP-ALL. A panel of these biomarkers might be useful in pinpointing the dominant lineage specification programmes in the ETP-ALL blasts on a personalized level, urging the development of novel lineage-directed precision therapies as well as repurposing of existing therapies against leukemia of different hematopoietic lineages; which might overcome the drawbacks of conventional chemotherapy.

Correlation study between blood cytokines and lymphocytes in early postoperative critical patients with compromised immune function

Major surgery due to traumatic injury can activate early systemic postoperative pro-inflammatory responses and postoperative immunosuppression. However, the interaction between them is complex and not entirely clear. This study was performed in postoperative patients admitted to the intensive care unit (ICU) to elucidate the correlation between the systemic cellular immunity function and circulating cytokines levels in the early postoperative period.Twenty-four cases of postoperative patients admitted to the ICU were enrolled in this study. Twelve hours after admission, blood routine examination and measurement of circulating cytokines (interleukin-2 [IL-2], IL-4, IL-6, IL-10, IL-17A, interferon-γ, tumor necrosis factor-alpha [TNF-α], TNF-β, granulocyte-colony stimulating factor [G-CSF], and granulocyte-macrophage colony-stimulating factor [GM-CSF]) were performed. The correlation analysis between cytokines levels and absolute peripheral blood lymphocyte count or lymphocytes/neutrophils ratio was analyzed.The cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, G-CSF, and GM-CSF) levels were increased above the normal upper limit at 12 hours after surgery. The number of leukocytes and neutrophils were markedly increased. In contrast, the absolute count and relative ratio of lymphocytes decreased below the lower normal limit. Spearman correlation analysis showed a moderate negative correlation between absolute peripheral blood lymphocyte count and IL-2 or IL-4 level. A low-negative correlation between absolute peripheral blood lymphocyte count and GM-CSF levels was detected. We also found that lymphocytes/neutrophils ratio was also negatively correlated with plasma IL-2, IL-4, or GM-CSF level.In ICU patients with compromised immune function in the early postoperative period, the elevated levels of IL-2, IL-4, and GM-CSF may be the compensatory responses to systemic immunosuppression.

Type II Cytokines Fine-Tune Thymic T Cell Selection to Offset Murine Central Nervous System Autoimmunity

Early thymic progenitors (ETPs) are bone marrow-derived hematopoietic stem cells that remain multipotent and give rise to a variety of lineage-specific cells. Recently, we discovered a subset of murine ETPs that expresses the IL-4Rα/IL-13Rα1 heteroreceptor (HR) and commits only to the myeloid lineage. This is because IL-4/IL-13 signaling through the HR inhibits their T cell potential and enacts commitment of HR⁺ETPs to thymic resident CD11c⁺CD8α⁺ dendritic cells (DCs). In this study, we discovered that HR⁺-ETP-derived DCs function as APCs in the thymus and promote deletion of myelin-reactive T cells. Furthermore, this negative T cell selection function of HR⁺-ETP-derived DCs sustains protection against experimental allergic encephalomyelitis, a mouse model for human multiple sclerosis. These findings, while shedding light on the intricacies underlying ETP lineage commitment, reveal a novel, to our knowledge, function by which IL-4 and IL-13 cytokines condition thymic microenvironment to rheostat T cell selection and fine-tune central tolerance.

Lineage Decision-Making within Normal Haematopoietic and Leukemic Stem Cells

To produce the wide range of blood and immune cell types, haematopoietic stem cells can “choose” directly from the entire spectrum of blood cell fate-options. Affiliation to a single cell lineage can occur at the level of the haematopoietic stem cell and these cells are therefore a mixture of some pluripotent cells and many cells with lineage signatures. Even so, haematopoietic stem cells and their progeny that have chosen a particular fate can still “change their mind” and adopt a different developmental pathway. Many of the leukaemias arise in haematopoietic stem cells with the bulk of the often partially differentiated leukaemia cells belonging to just one cell type. We argue that the reason for this is that an oncogenic insult to the genome “hard wires” leukaemia stem cells, either through development or at some stage, to one cell lineage. Unlike normal haematopoietic stem cells, oncogene-transformed leukaemia stem cells and their progeny are unable to adopt an alternative pathway.