Biology subjects

Leonard, W. J.

Publications and source records attributed to Leonard, W. J..

6 recordsLinked to original sources

bioRxiv2026

FOXP-stabilization of the Il2ra super-enhancer structure augments Treg fitness

Gene expression in regulatory T cells (Tregs) is context-dependent and maintains peripheral immune homeostasis. FOXP3 is lineage defining but not sufficient for Treg function or persistence. To define the cell-intrinsic roles of the FOXP3 paralogs FOXP1 and FOXP4, we generated and studied mice with Treg-specific deletion of Foxp1 and/or Foxp4. FOXP1 and FOXP4 are required to maintain the peripheral Treg pool through enhancing Il2ra transcription, thereby promoting sustained high-level expression of IL-2R and thus of the high-affinity IL-2R{beta}{gamma} complex. Integrating RNA-seq and ATAC-seq with previously published ChIA-PET and publicly available data, we propose a model of Il2ra transcriptional regulation in which in which FOXP1 and FOXP4 anchor chromatin looping of the Il2ra locus in mature Tregs, augment super-enhancer activity, and drive sustained CD25 expression. Our results reveal a unique role of FOXP1, and to a lesser extent FOXP4, in controlling Treg homeostasis. One Sentence SummaryFOXP1 and FOXP4 regulate chromatin architecture at the Il2ra locus, promoting sustained CD25 expression and maintaining the peripheral Treg pool.

immunology↗

bioRxiv2026

ISG15 orchestrates dynamic crosstalk between mitochondrial fat oxidation and type 1 interferon in myeloid cells

In contrast to Krebs cycle intermediates, the role of mitochondrial fatty acid oxidation (FAO) in immunometabolism remains incompletely characterized. Studying primary bone marrow-derived macrophages (BMDMs), we show that IFN-{beta} and STING activation augments FAO and associated enzymes carnitine palmitoyltransferase 1a (CPT1a) and acetyl-CoA acetyltransferase 1 (ACAT1). Depleting BMDM Cpt1a reduces FAO and dampens type 1 interferon (IFN) signaling due to decreased histone H3-K9/K14 acetylation, supporting the prior finding of an epigenetic role of FAO in sustaining type 1 IFN. Interestingly, FAO induction by IFN was dynamic as a heightened IFN response suppressed FAO, suggesting a concurrent negative-feedback mechanism. This FAO blunting correlated with increased expression of interferon-stimulated gene 15 (ISG15), a ubiquitin-like modifier known to modulate metabolic proteins through ISGylation. This immune-metabolic signature was similarly operational in mice infected with lymphocytic choriomenigitis virus (LCMV) with temporal discordance between ISG15 levels and FAO. The role of ISG15 in this negative feedback was shown with increased FAO and type 1 IFN response in Isg15 knockout BMDMs. Parallely, endogenous co-immunoprecipitation showed interactions between ISG15 and CPT1a/ACAT1. This ISG15-FAO regulatory interaction was also evident in systemic lupus erythematosus (SLE)-associated interferonopathy and in primary monocytes from SLE individuals that exhibited increased ISG15 levels and reduced FAO rates. Collectively, these findings support a model in which type 1 IFN initially enhances FAO to amplify interferon production, but excessive IFN-signaling induces ISG15-mediated inhibition of FAO, a putative feedback loop that restrains inflammation and preserves immune homeostasis. Together these data identify a novel biphasic FAO-dependent immunometabolic regulatory program. Graphical Summary O_FIG O_LINKSMALLFIG WIDTH=190 HEIGHT=200 SRC="FIGDIR/small/700051v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@13f572eorg.highwire.dtl.DTLVardef@174b6aeorg.highwire.dtl.DTLVardef@1856483org.highwire.dtl.DTLVardef@89e5a6_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIType 1 IFN rewires myeloid cell metabolism towards FAO. C_LIO_LIFAO epigenetically fuels Type 1 1IFN response. C_LIO_LIEffect of IFN on FAO is dynamic: inducing FAO at low concentrations while suppressing it during a heightened IFN response. C_LIO_LIEnhanced Type 1 IFN response produces ISG15 which ISGylates key enzymes of FAO altering their stability C_LIO_LIISG15 negatively regulates FAO to control Type 1 IFN homeostasis in a negative feedback loop. C_LI

immunology↗

bioRxiv2024

Potent antitumor activity of a designed interleukin-21 mimic

Long-standing goals of cancer immunotherapy are to activate cytotoxic antitumor T cells across a broad range of affinities while dampening suppressive regulatory T (Treg) cell responses, but current approaches achieve these goals with limited success. Here, we report a de novo IL-21 mimic, 21h10, designed to have augmented stability and high signaling potency in both humans and mice. In multiple animal models and in ex vivo human melanoma patient derived organotypic tumor spheroids (PDOTS), 21h10 showed robust antitumor activity. 21h10 generates significantly prolonged STAT signaling in vivo compared with native IL-21, and has considerably stronger anti-tumor activity. Toxicities associated with systemic administration of 21h10 could be mitigated by TNF blockade without compromising antitumor efficacy. In the tumor microenvironment, 21h10 induced highly cytotoxic antitumor T cells from clonotypes with a range of affinities for endogenous tumor antigens, robustly expanding low-affinity cytotoxic T cells and driving high expression of interferon- (IFN-) and granzyme B compared to native IL-21, while increasing the frequency of IFN-+ Th1 cells and reducing that of Foxp3+ Tregs. As 21h10 has full human/mouse cross-reactivity, high stability and potency, and potentiates low-affinity antitumor responses, it has considerable translational potential.

biochemistry↗

bioRxiv2023

A new pipeline SPICE identifies novel JUN-IKZF1 composite elements

Transcription factor partners can cooperatively bind to DNA composite elements to augment gene transcription. Here, we report a novel protein-DNA binding screening pipeline, termed Spacing Preference Identification of Composite Elements (SPICE), that can systematically predict protein binding partners and DNA motif spacing preferences. Using SPICE, we successfully identified known composite elements, such as AP1-IRF composite elements (AICEs) and STAT5 tetramers, and also uncovered several novel binding partners, including JUN-IKZF1 composite elements. One such novel interaction was identified at CNS9, an upstream conserved noncoding region in the human IL10 gene, which harbors a non-canonical IKZF1 binding site. We confirmed cooperative binding of JUN and IKZF1 and showed that the activity of an IL10-luciferase reporter construct in primary B and T cells depended on both this site and the AP1 binding site within this composite element. Overall, our findings reveal an unappreciated global association of IKZF1 and AP1 and establish SPICE as a valuable new pipeline for predicting novel transcription binding complexes.

systems biology↗

bioRxiv2023

Engineered cytokine/antibody fusion proteins improve delivery of IL-2 to pro-inflammatory cells and promote antitumor activity

Progress in cytokine engineering is driving therapeutic translation by overcoming the inherent limitations of these proteins as drugs. The interleukin-2 (IL-2) cytokine harbors great promise as an immune stimulant for cancer treatment. However, the cytokines concurrent activation of both pro-inflammatory immune effector cells and anti-inflammatory regulatory T cells, its toxicity at high doses, and its short serum half-life have limited clinical application. One promising approach to improve the selectivity, safety, and longevity of IL-2 is complexation with anti-IL-2 antibodies that bias the cytokine towards the activation of immune effector cells (i.e., effector T cells and natural killer cells). Although this strategy shows therapeutic potential in preclinical cancer models, clinical translation of a cytokine/antibody complex is complicated by challenges in formulating a multi-protein drug and concerns about complex stability. Here, we introduce a versatile approach to designing intramolecularly assembled single-agent fusion proteins (immunocytokines, ICs) comprising IL-2 and a biasing anti-IL-2 antibody that directs the cytokines activities towards immune effector cells. We establish the optimal IC construction and further engineer the cytokine/antibody affinity to improve immune biasing function. We demonstrate that our IC preferentially activates and expands immune effector cells, leading to superior antitumor activity compared to natural IL-2 without inducing toxicities associated with IL-2 administration. Collectively, this work presents a roadmap for the design and translation of immunomodulatory cytokine/antibody fusion proteins. One Sentence SummaryWe developed an IL-2/antibody fusion protein that expands immune effector cells and shows superior tumor suppression and toxicity profile versus IL-2.

bioengineering↗

bioRxiv2022

Distinct super-enhancer elements differentially control Il2ra gene expression in a cell-type specific fashion

The IL-2 receptor -chain (IL-2R/CD25) is constitutively expressed on DN2/DN3 thymocytes and Treg cells but induced by IL-2 on mature T and NK cells. Il2ra expression is regulated by a super-enhancer extensively bound by STAT5 in mature T cells. Here, we demonstrate that STAT5 cooperates with Notch to induce/maintain Il2ra/CD25 expression in DN2/DN3 cells. Moreover, we systematically investigated CD25 regulation using a series of mice with deletions spanning STAT5 binding elements. Deleting the upstream super-enhancer region mainly affected constitutive CD25 expression on DN2/DN3 thymocytes and Tregs, whereas deleting an intronic region primarily decreased IL-2-induced CD25 on peripheral T and NK cells. Thus, distinct elements preferentially control constitutive versus inducible expression in a cell-type-specific manner, with the MED1 coactivator co-localizing with specific STAT5 binding sites. Moreover, the intronic region was a dominant element whose deletion altered the structure throughout the super-enhancer in mature T cells. These results demonstrate differential functions for distinct super-enhancer elements, thereby indicating ways to manipulate CD25 expression in a cell-type specific fashion.

immunology↗