OBJECTIVE:Oral administration of an antigen can induce immunological tolerance. Insulin is an autoantigen in childhood type 1 diabetes (T1D). We tested the effect of treatment with high-dose oral insulin on disease progression and immune response to insulin in children with stage 1 T1D. RESEARCH DESIGN AND METHODS:We conducted a phase 2 randomized placebo-controlled double-blind trial in children with stage 1 T1D who received daily oral insulin (7.5 mg/day for 3 months and 67.5 mg/day for 9 months; n = 110) or placebo (n = 110) for 12 months. The coprimary outcomes were 1) time from baseline to dysglycemia or clinical diabetes and 2) increased immune response to insulin within 12 months of treatment (assessed in the first 90 participants). RESULTS:Of 220 participants (112 girls; median age 4.8 years; interquartile range 3.6, 6.2), 179 completed the trial. Dysglycemia or diabetes developed in 87 participants (46 receiving oral insulin and 41 receiving placebo; hazard ratio 1.07; 95% CI 0.66-1.73; P = 0.74). The 5-year progression rate was 40% (95% CI 30-51%) in each group. A modest treatment interaction was found with the INS rs689 genotype (P = 0.03). Increased immune response to insulin was observed in 11 (25%) of 44 participants in the oral insulin group and 13 (31%) of 42 in the placebo group (P = 0.63). Oral insulin was well tolerated. No significant study-related adverse events occurred. CONCLUSIONS:In children with stage 1 T1D, 1 year of high-dose oral insulin did not alter progression to dysglycemia or diabetes or immune response to insulin.

The chromatin organizer SATB1 is indispensable for thymic regulatory T cell (Treg cell) development and T helper cell induction. Several gene loci have been described to be SATB1-controlled, including the transcription factor GATA3 and the cytokine loci IL-4 and IL-17. However, the global effects of SATB1 on fully differentiated human CD4 conventional T cells (Tconv cells) and Treg cells, and thus the potential of SATB1 as a target for T-cell engineering, are poorly understood. Here, we describe SATB1-regulated gene signatures as largely subset-specific, with broader effects on Treg cells. Despite distinct gene-regulatory patterns, we observe overarching dysregulated cytokine and JAK-STAT signaling after SATB1 ablation. Functionally, SATB1 KO reduces suppressive capacities of human Treg cells but boosts tumor clearance via CD4 CAR T cells in a preclinical, humanized mouse model. Taken together, Treg destabilization and simultaneous increased activation of CD4 CAR T cells by SATB1 modulation may be a strategy to boost the efficiency of CAR T cell therapies.

Atherosclerosis is a long-term complication of obesity and diabetes and as such a key driver of vascular dysfunction and eventually mortality in affected patients. Both aberrant lipid metabolism and inflammatory reactions promote atherosclerotic plaque development in the vessel wall by triggering a cascade of cellular events involving multiple cell types, including smooth muscle cells, monocytic macrophages, and lymphocytes. Despite its eminent impact on human health, molecular drivers of cellular dysfunction in atherosclerosis remain poorly defined and therapeutic options are scarce.Here we show by single-cell RNA sequencing that the expression of the nuclear receptor co-factors, TBL1X and TBL1XR1, was particularly prominent in the CD4+ T cell population of human carotid artery plaques. Indeed, genetic double deletion of TBL1X/TBL1XR1 in CD4+ T cells led to a substantial shift from naïve CD44lowCD62Lhi cells to CD44hiCD62Llow effector and Foxp3+ Tregs. CD4+ TBL1X/TBL1XR1 KO cells exhibited enhanced cytokine production capacity upon ionomycin/PMA stimulation, correlating with the induction of pro-inflammatory and cytokine-producing transcriptional pathways in these cells. Consistently, transplantation of bone marrow from CD4+-specific TBL1X/TBL1XR1 knock out mice into LDLR KO recipients doubled the development of atherosclerotic plaques in the aortic arch compared with wild-type bone marrow transplanted littermates. As TBL1X/TBL1XR1 expression levels were diminished in carotid arteries from patients with advanced unstable plaques compared to stable plaques or healthy controls, these data suggest that aberrant inhibition of TBL1X/TBL1XR1 in CD4+ T cells may contribute to the development of atherosclerosis in humans. Restoration of TBL1X/TBL1XR1 functionality may thus serve as a novel, druggable strategy for preventing or limiting atherosclerosis progression.

The hypothalamus in the central nervous system (CNS) has important functions in controlling systemic metabolism. A calorie-rich diet triggers CNS immune activation, impairing metabolic control and promoting obesity and Type 2 Diabetes (T2D), but the mechanisms driving hypothalamic immune activation remain unclear. Here we identify regulatory T cells (Tregs) as key modulators of hypothalamic immune responses. In mice, calorie-rich environments activate hypothalamic CD4+ T cells, infiltrating macrophages and microglia while reducing hypothalamic Tregs. mRNA profiling of hypothalamic CD4+ T cells reveals a Th1-like activation state, with increased Tbx21, Cxcr3 and Cd226 but decreased Ccr7 and S1pr1. Importantly, results from Treg loss-of function and gain-of-function experiments show that Tregs limit hypothalamic immune activation and reverse metabolic impairments induced by hyper-caloric feeding. Our findings thus help refine the current model of Treg-centered immune-metabolic crosstalk in the brain and may contribute to the development of precision immune modulation for obesity and diabetes.

The immune balance in mucosal tissues depends on a delicate interplay between inflammatory T helper 17 (Th17) cells and immunosuppressive regulatory T cells (Tregs). But what happens when this balance is disturbed? In this study, we uncovered a critical role for Acyl-CoA synthetase bubblegum family member 1 (Acsbg1) in shaping Th17 and Treg dynamics. Using Acsbg1-deficient mice, we show that while its absence does not disrupt homeostasis under steady-state conditions, it significantly alters Treg populations, particularly in gut-associated tissues. Under high-fat diet-induced metabolic stress, Acsbg1-deficient mice display mild metabolic changes but maintain systemic immune and metabolic function, indicating that Acsbg1 is dispensable for metabolic adaptation in vivo. However, upon infection with Citrobacter rodentium, these mice exhibit excessive Th1/Th17-driven inflammation and impaired resolution, accompanied by a strong reduction in IL-10-producing and ST2+ Treg subsets. The impact is even more striking in an adoptive transfer colitis model, where Acsbg1-deficient Tregs fail to control inflammation, resulting in severe colitis and tissue damage. Our findings identify Acsbg1 as a key regulator of ST2+ Treg function and a central player in mucosal immune homeostasis, highlighting its potential as a therapeutic target for inflammatory bowel disease and colorectal cancer.

Introduction:Treating autoimmune diseases without nonspecific immunosuppression remains challenging. To prevent or treat these conditions through targeted immunotherapy, we developed a clinical-stage nanoparticle platform that leverages the tolerogenic capacity of liver sinusoidal endothelial cells (LSECs) to restore antigen-specific immune tolerance. Methods:In vivo efficacy was evaluated in various CD4+ T cell-mediated disease models, including preventive and therapeutic models of myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (EAE), ovalbumin-sensitized delayed-type hypersensitivity (DTH), and the spontaneous type 1 diabetes model. Nanoparticle-induced antigen-specific immune responses were also analyzed through adoptive transfers of 2D2 transgenic T cells into wild-type mice, followed by nanoparticle administration. Results:The peptide-conjugated nanoparticles displayed a uniform size distribution (25-30 nm). Their coupling efficiency for peptides with unfavorable physicochemical properties was significantly enhanced by a proprietary linker technology. Preferential LSEC targeting of nanoparticles coupled with fluorescently labeled peptides was confirmed via intravital microscopy and flow cytometry. Intravenous nanoparticle administration significantly reduced disease severity and demyelination in EAE, independent of prednisone at maintenance doses, and suppressed target tissue inflammation in the DTH model. Furthermore, prophylactic administration of a mixture of nanoparticles coupled with five autoantigenic peptides significantly lowered the hyperglycemia incidence of the non-obese diabetic mice. Mechanistically, the tolerizing effects were associated with the induction of antigen-specific regulatory T cells and T cell anergy, which counteract proinflammatory T cells in the target tissue. Conclusion:Our findings demonstrate that peptide-loaded nanoparticles preferentially deliver disease-relevant peptides to LSECs, thereby inducing antigen-specific immune tolerance. This versatile clinical-stage nanoparticle platform holds promise for clinical application across multiple autoimmune diseases.

OBJECTIVE:In autoimmune Type 1 Diabetes (T1D), aberrant immune activation promotes regulatory T cell (Treg) impairments thereby boosting progression of islet autoimmunity. Consequently, there is a progressive destruction of the insulin-producing beta cells in the pancreas. Controlling overshooting immune activation represents a relevant approach to allow for efficient Treg-targeting by broadening the window of opportunity to induce Tregs. METHODS:We investigated the effect of restricting pyrimidine de novo synthesis during islet autoimmunity and T1D by Dihydroorotate dehydrogenase (DHODH) inhibition using the next-generation DHODH inhibitor Vidofludimus calcium. We assessed Treg-inducing features of DHODH inhibition in T cells from ongoing murine islet autoimmunity and human T1D in vitro. To dissect the functional relevance of these observations, we tested the impact of DHODH inhibition on interfering with autoimmune activation and disease progression in pre-clinical models of T1D in vivo. RESULTS:We show that DHODH inhibition results in enhanced Treg induction in vitro especially during increased immune activation and reduced T cell proliferation. In addition, Vidofludimus calcium reduced T1D incidence in two mouse models. On the cellular level, treated mice showed reduced T cell activation accompanied by increased Treg frequencies. CONCLUSIONS:We demonstrate that restricting pyrimidine de novo synthesis by next-generation DHODH inhibition is a strategy to interfere with autoimmune activation while fostering Tregs.

The mechanisms by which genomic risks contribute to the onset of neuropsychiatric conditions remain a key challenge and a prerequisite for successful development of effective therapies. 15q11.2 copy number variation (CNV) containing the CYFIP1 gene is associated with autism and schizophrenia. Using stem cell models, we show that 15q11.2 deletion (15q11.2del) and CYFIP1 loss of function (CYFIP1-LoF) lead to premature neuronal differentiation, while CYFIP1 gain of function (CYFIP1-GoF) favors neural progenitor maintenance. CYFIP1 dosage changes led to dysregulated cholesterol metabolism and altered levels of 24S,25-epoxycholesterol, which can mimic the 15q11.2del and CYFIP1-LoF phenotypes by promoting cortical neuronal differentiation and can restore the impaired neuronal differentiation of CYFIP1-GoF neural progenitors. Moreover, the neurogenic activity of 24S,25-epoxycholesterol is lost following genetic deletion of liver X receptor ( LXRb ), while compound deletion of LXRb in CYFIP1 - / - background rescued their premature neurogenesis. This work delineates LXR-mediated oxysterol regulation of neurogenesis as a pathological mechanism in neural cells carrying 15q11.2 CNV and provides a potential target for therapeutic strategies for associated disorders.

Tissue regulatory T cells (Tregs) exert pivotal functions in both immune and metabolic regulation, maintaining local tissue homeostasis, integrity, and function. Accordingly, Tregs play a crucial role in controlling obesity-induced inflammation and supporting efficient muscle function and repair. Depending on the tissue context, Tregs are characterized by unique transcriptomes, growth, and survival factors and T cell receptor (TCR) repertoires. This functional specialization offers the potential to selectively target context-specific Treg populations, tailoring therapeutic strategies to specific niches, thereby minimizing potential side effects. Here, we discuss challenges and perspectives for niche-specific Treg targeting, which holds promise for highly efficient and precise medical interventions to combat metabolic disease.

The regulation of thymocyte development by RNA-binding proteins (RBPs) is largely unexplored. We identify 642 RBPs in the thymus and focus on Arpp21, which shows selective and dynamic expression in early thymocytes. Arpp21 is downregulated in response to T cell receptor (TCR) and Ca 2+ signals. Downregulation requires Stim1/Stim2 and CaMK4 expression and involves Arpp21 protein phosphorylation, polyubiquitination and proteasomal degradation. Arpp21 directly binds RNA through its R3H domain, with a preference for uridine-rich motifs, promoting the expression of target mRNAs. Analysis of the Arpp21–bound transcriptome reveals strong interactions with the Rag1 3′-UTR. Arpp21–deficient thymocytes show reduced Rag1 expression, delayed TCR rearrangement and a less diverse TCR repertoire. This phenotype is recapitulated in Rag1 3′-UTR mutant mice harboring a deletion of the Arpp21 response region. These findings show how thymocyte-specific Arpp21 promotes Rag1 expression to enable TCR repertoire diversity until signals from the TCR terminate Arpp21 and Rag1 activities.

Muscle-residing regulatory T cells (Tregs) control local tissue integrity and function. However, the molecular interface connecting Treg-based regulation with muscle function and regeneration remains largely unexplored. Here, we show that exercise fosters a stable induction of highly functional muscle -residing Tregs with increased expression of amphiregulin (Areg), EGFR, and ST2. Mechanistically, we find that mice lacking IL6Ra on T cells (TKO) harbor significant reductions in muscle Treg functionality and satellite and fibro-adipogenic progenitor cells, which are required for muscle regeneration. Using ex-ercise and sarcopenia models, IL6Ra TKO mice demonstrate deficits in Tregs, their functional matura-tion, and a more pronounced decline in muscle mass. Muscle injury models indicate that IL6Ra TKO mice have significant disabilities in muscle regeneration. Treg gain of function restores impaired muscle repair in IL6Ra TKO mice. Of note, pharmacological IL6R blockade in WT mice phenocopies deficits in muscle function identified in IL6Ra TKO mice, thereby highlighting the clinical implications of the findings.

PDF file - 547K, cytokineproduction of spleen cells and LPMC

Dysregulation in neural progenitor proliferation and neuronal differentiation has been increasingly recognised as a common pathology in neural cells harboring genetic risks to neuropsychiatric and neurodevelopmental disorders, yet the underlying molecular mechanisms remains largely unknown. Deletions and duplications of the 15q11.2 region containing the CYFIP1 gene have been associated with autism and schizophrenia. Using patient-derived iPSCs carrying 15q11.2 deletion and genetically manipulated hESCs with CYFIP1 gain- and loss-of-function (GoF and LoF), we show that 15q11.2 deletion and CYFIP1-LoF leads to premature neuronal differentiation while CYFIP1-GoF favours neural progenitor maintenance. We identified cholesterol biosynthesis and metabolism as a biological process disturbed by CYFIP1 dosage change, leading to altered neuro-oxysterol profiles. 24S,25-epoxycholesterol, which was decreased in CYFIP1-GoF and increased in CYFIP1-LoF and 15q11.2del neural cells, can mimic the 15q11.2del and CYFIP1-LoF phenotype by promoting cortical neuronal differentiation and restore the impaired neuronal differentiation of CYFIP1-GoF neural progenitors. Moreover, the neurogenic activity of 24S,25-epoxycholesterol is lost following genetic deletion of the brain expressed isoform of the liver X receptor LXRb while compound deletion of LXRb in CYFIP1-/- background rescued their premature neurogenesis. This work delineates LXR mediated oxysterol regulation of neurogenesis as a novel pathological mechanism in neural cells carrying 15q11.2CNV and provides a potential target for therapeutic strategies for genetic disorders associated with this risk locus.

PDF file - 112K, expression of cox-2 and VEGF

PDF file - 660K, staining of EpCAM and IL-6 in cytospin preparation

PDF file - 419K, table of patient data for supplementary figures