Search

A20 is a dual-function ubiquitin-editing enzyme that maintains immune homeostasis by restraining inflammation. Although A20 serves a similar negative feedback function for T-cell receptor (TCR) signaling, the molecular mechanisms utilized and their ultimate impact on human T-cell function remain unclear. TCR engagement triggers the assembly of the CARD11-BCL10-MALT1 (CBM) protein complex, a signaling platform that governs the activation of downstream transcription factors including NF-κB and c-Jun/AP-1. Utilizing WT and A20 knockout Jurkat T cells, we found that A20 is required to negatively regulate NF-κB and JNK. Utilizing a novel set of A20 mutants in NF-κB and AP-1-driven reporter systems, we discovered the ZnF7 domain is crucial for negative regulatory capacity, while deubiquitinase activity is dispensable. Successful inactivation of A20 in human primary effector T cells congruently conferred sustained NF-κB and JNK signaling, including enhanced upregulation of activation markers, and increased secretion of several cytokines including IL-9. Finally, loss of A20 in primary human T cells resulted in decreased sensitivity to restimulation-induced cell death and increased sensitivity to cytokine withdrawal-induced death. These findings demonstrate the importance of A20 in maintaining T-cell homeostasis via negative regulation of both NF-κB and JNK signaling., (© 2024 Wiley‐VCH GmbH.)

The caspase activation and recruitment domain 11 (CARD11) gene encodes a scaffold protein required for lymphocyte antigen receptor signaling. Dominant-negative, loss-of-function (LOF) pathogenic variants in CARD11 result in CARD11-associated atopy with dominant interference of NF-κB signaling (CADINS) disease. Patients with CADINS suffer with severe atopic manifestations including atopic dermatitis, food allergy, and chronic spontaneous urticaria in addition to recurrent infections and autoimmunity. We assessed the response of dupilumab in five patients and omalizumab in one patient with CADINS for the treatment of severe atopic symptoms. CARD11 mutations were validated for pathogenicity using a T cell transfection assay to assess the impact on activation-induced signaling to NF-κB. Three children and three adults with dominant-negative CARD11 LOF mutations were included. All developed atopic disease in infancy or early childhood. In five patients, atopic dermatitis was severe and recalcitrant to standard topical and systemic medications; one adult suffered from chronic spontaneous urticaria. Subcutaneous dupilumab was initiated to treat atopic dermatitis and omalizumab to treat chronic spontaneous urticaria. All six patients had rapid and sustained improvement in atopic symptoms with no complications during the follow-up period. Previous medications used to treat atopy were able to be decreased or discontinued. In conclusion, treatment with dupilumab and omalizumab for severe, refractory atopic disease in patients with CADINS appears to be effective and well tolerated in patients with CADINS with severe atopy., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare primary cutaneous non-Hodgkin lymphoma involving CD8 + T cells, the genetic underpinnings of which remain incompletely understood. Here we report two unrelated patients with B cell Expansion with NF-κB and T cell Anergy (BENTA) disease and a novel presentation of SPTCL. Patient 1 presented early in life with recurrent infections and B cell lymphocytosis, linked to a novel gain-of-function (GOF) CARD11 mutation (p.Lys238del). He developed SPTCL-like lesions and membranoproliferative glomerulonephritis by age 2, treated successfully with cyclosporine. Patient 2 presented at 13 months with splenomegaly, lymphadenopathy, and SPTCL with evidence of hemophagocytic lymphohistiocytosis. Genetic analysis revealed two in cis germline GOF CARD11 variants (p.Glu121Asp/p.Gly126Ser). Autologous bone marrow transplant resulted in SPTCL remission despite persistent B cell lymphocytosis. These cases illuminate an unusual pathological manifestation for BENTA disease, suggesting that CARD11 GOF mutations can manifest in cutaneous CD4 + and CD8 + T cell malignancies., Competing Interests: Declaration of Competing Interest None., (Published by Elsevier Inc.)

Immune homeostasis depends upon effective clearance of pathogens while simultaneously preventing autoimmunity and immunopathology in the host. Restimulation-induced cell death (RICD) is one such mechanism where by activated T cells receive subsequent antigenic stimulation, reach a critical signal threshold through the T cell receptor (TCR), and commit to apoptosis. Many details of this process remain unclear, including the role of co-stimulatory and co-inhibitory proteins that influence the TCR signaling cascade. Here we characterize the role of T cell immunoglobulin and mucin domain containing 3 (TIM-3) in RICD regulation. TIM-3 protected newly activated CD8 + effector T cells from premature RICD during clonal expansion. Surprisingly, however, we found that TIM-3 potentiated RICD in late-stage effector T cells. The presence of TIM-3 increased proximal TCR signaling and proapoptotic protein expression in late-stage effector T cells, with no consistent signaling effects noted in newly activated cells with or without TIM-3. To better explain these differences in TIM-3 function as T cells aged, we characterized the temporal pattern of TIM-3 expression in effector T cells. We found that TIM-3 was expressed on the surface of newly activated effector T cells, but remained largely intracellular in late-stage effector cells. Consistent with this, TIM-3 required a ligand to prevent early RICD, whereas ligand manipulation had no effects at later stages. Of the known TIM-3 ligands, carcinoembryonic antigen-related cell adhesion molecule (CEACAM1) showed the greatest difference in surface expression over time and also protected newly activated cells from premature RICD, with no measurable effects in late-stage effectors. Indeed, CEACAM1 enabled TIM-3 surface expression on T cells, implying a co-dependency for these proteins in protecting expanding T cells from premature RICD. Our findings suggest that co-signaling proteins like TIM-3 and CEACAM1 can alter RICD sensitivity at different stages of the effector T cell response, with important implications for checkpoint blockade therapy.

The adaptive immune response relies on specific apoptotic programs to maintain homeostasis. Conventional effector T cell (Tcon) expansion is constrained by both forkhead box P3 (FOXP3) + -regulatory T cells (Tregs) and restimulation-induced cell death (RICD), a propriocidal apoptosis pathway triggered by repeated stimulation through the T-cell receptor (TCR). Constitutive FOXP3 expression protects Tregs from RICD by suppressing SLAM-associated protein (SAP), a key adaptor protein that amplifies TCR signaling strength. The role of transient FOXP3 induction in activated human CD4 and CD8 Tcons remains unresolved, but its expression is inversely correlated with acquired RICD sensitivity. Here, we describe a novel role for FOXP3 in protecting human Tcons from premature RICD during expansion. Unlike FOXP3-mediated protection from RICD in Tregs, FOXP3 protects Tcons through a distinct mechanism requiring de novo transcription that does not require SAP suppression. Transcriptome profiling and functional analyses of expanding Tcons revealed that FOXP3 enhances expression of the SLAM family receptor CD48, which in turn sustains basal autophagy and suppresses pro-apoptotic p53 signaling. Both CD48 and FOXP3 expression reduced p53 accumulation upon TCR restimulation. Furthermore, silencing FOXP3 expression or blocking CD48 decreased the mitochondrial membrane potential in expanding Tcons with a concomitant reduction in basal autophagy. Our findings suggest that FOXP3 governs a distinct transcriptional program in early-stage effector Tcons that maintains RICD resistance via CD48-dependent protective autophagy and p53 suppression.

Genetic testing has increased the number of variants identified in disease genes, but the diagnostic utility is limited by lack of understanding variant function. CARD11 encodes an adaptor protein that expresses dominant-negative and gain-of-function variants associated with distinct immunodeficiencies. Here, we used a "cloning-free" saturation genome editing approach in a diploid cell line to simultaneously score 2,542 variants for decreased or increased function in the region of CARD11 associated with immunodeficiency. We also described an exon-skipping mechanism for CARD11 dominant-negative activity. The classification of reported clinical variants was sensitive (94.6%) and specific (88.9%), which rendered the data immediately useful for interpretation of seven coding and splicing variants implicated in immunodeficiency found in our clinic. This approach is generalizable for variant interpretation in many other clinically actionable genes, in any relevant cell type., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: The interaction between isoflavones and the gut microbiota has been highlighted as a potential regulator of obesity and diabetes. In this study, we examined the interaction between isoflavones and a shortened activity photoperiod on the gut microbiome., Methods: Male mice were exposed to a diet containing no isoflavones (NIF) or a regular diet (RD) containing the usual isoflavones level found in a standard vivarium chow. These groups were further divided into regular (12L:12D) or short active (16L:8D) photoperiod, which mimics seasonal changes observed at high latitudes. White adipose tissue and genes involved in lipid metabolism and adipogenesis processes were analysed. Bacterial genomic DNA was isolated from fecal boli, and 16S ribosomal RNA sequencing was performed., Results: NIF diet increased body weight and adipocyte size when compared to mice on RD. The lack of isoflavones and photoperiod alteration also caused dysregulation of lipoprotein lipase ( Lpl ), glucose transporter type 4 ( Glut-4 ) and peroxisome proliferator-activated receptor gamma ( Pparg ) genes. Using 16S ribosomal RNA sequencing, we found that mice fed the NIF diet had a greater proportion of Firmicutes than Bacteroidetes when compared to animals on the RD. These alterations were accompanied by changes in the endocrine profile, with lower thyroid-stimulating hormone levels in the NIF group compared to the RD. Interestingly, the NIF group displayed increased locomotion as compared to the RD group., Conclusion: Together, these data show an interaction between the gut bacterial communities, photoperiod length and isoflavone compounds, which may be essential for understanding and improving metabolic health., (© 2020 The Authors. Endocrinology, Diabetes & Metabolism published by John Wiley & Sons Ltd.)

Photoperiod and diet are factors known to modulate the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, shifts in photoperiod have been previously linked with affective and anxiety disorders. Furthermore, isoflavones have been shown to mediate behavioral outcome in response to the environment of the animal. Here, we investigated the effect of photoperiod alteration on the HPA axis and how the addition of isoflavones might modulate the response to stress. Male C57BL/6J mice were maintained on either a 12:12 or a 16:8 light-dark (LD) cycle for 10 days, and fed a diet of either standard rodent chow or an isoflavone free (IF) chow beginning 3 weeks prior to light alteration. Consistent with previous work, mice in the shorter active period (16:8 LD cycle) showed increased basal corticosterone (CORT) secretion. In the absence of isoflavones, this response was attenuated. Increases in mineralcorticoid (MR) and glucocorticoid (GR) receptor mRNA expression were seen in the pituitary following photoperiod alteration. However, animals fed the standard isoflavone rich chow showed increases in the ratio of MR:GR mRNA in the anterior bed nucleus of the stria terminalis following photoperiod alteration. Decreases in corticotrophin-releasing factor receptor 1 (CRFR1) mRNA expression were seen in animals fed the IF chow in the amygdala, prefrontal cortex and ventral hippocampus. These data suggest that alterations in CORT secretion following photoperiod alteration may be mediated through differences in CRFR1 gene expression or changes in MR:GR mRNA ratios. These findings provide insight into the potential mechanisms by which the HPA axis adapts to photoperiod and diet., (Published by Elsevier Ltd.)

The caspase recruitment domain family member 11 (CARD11 or CARMA1)-B cell CLL/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) [CBM] signalosome complex serves as a molecular bridge between cell surface antigen receptor signaling and the activation of the NF-κB, JNK, and mTORC1 signaling axes. This positions the CBM complex as a critical regulator of lymphocyte activation, proliferation, survival, and metabolism. Inborn errors in each of the CBM components have now been linked to a diverse group of human primary immunodeficiency diseases termed "CBM-opathies." Clinical manifestations range from severe combined immunodeficiency to selective B cell lymphocytosis, atopic disease, and specific humoral defects. This surprisingly broad spectrum of phenotypes underscores the importance of "tuning" CBM signaling to preserve immune homeostasis. Here, we review the distinct clinical and immunological phenotypes associated with human CBM complex mutations and introduce new avenues for targeted therapeutic intervention.

The transcription factor Nrf2 is a master regulator of antioxidant and cytoprotective genes, binding to antioxidant response elements (AREs) in their promoter regions. Due to the therapeutic role of the Nrf2/ARE system in oxidative homeostasis, its activation has been investigated in many pre-clinical and clinical trials for common chronic diseases. One of the most promising Nrf2 activators is sulforaphane, the subject of over 50 clinical trials. In this work, we examine the effect of reactive oxygen species (ROS) on sulforaphane's Nrf2/ARE activation in the non-tumorigenic keratinocyte cell line HaCaT, with the non-arylating oxidizable phenol, 2,5-di-tert-butylhydroquinone (dtBHQ), as the source of ROS. We find that, in combination with 2.5 µM sulforaphane, dtBHQ markedly enhances ARE-regulated gene expression, including expression of the cytoprotective proteins aldo-keto reductase family 1 member C1 (AKR1C1) and heme oxygenase-1 (HO-1). Additionally, sulforaphane's therapeutic window is widened by 12.5 µM dtBHQ. Our data suggest that H 2 O 2 generated by dtBHQ oxidation is responsible for these effects, as shown by inclusion of catalase and by co-treatment with sulforaphane and H 2 O 2 . While sulforaphane treatment causes Nrf2 protein to accumulate as expected, interestingly, dtBHQ and H 2 O 2 appear to act on targets downstream of Nrf2 protein accumulation to enhance sulforaphane's ARE-regulated gene expression. Inclusion of dtBHQ or H 2 O 2 with sulforaphane does not increase Nrf2 protein levels, and catalase has little effect on Nrf2 protein levels in the presence of sulforaphane and dtBHQ. Surprisingly, dtBHQ suppresses Nrf2 protein synthesis. Inclusion of a superoxide dismutase mimetic with sulforaphane and dtBHQ partly rescues Nrf2 suppression and significantly further increases sulforaphane's efficacy for ARE-reporter expression. Thus, there is a "Dr. Jekyll and Mr. Hyde" effect of ROS: ROS enhance sulforaphane's ARE-regulated gene expression even as they also inhibit Nrf2 protein synthesis. This unexpected finding reveals the degree to which targets in the ARE pathway downstream of Nrf2 protein accumulation contribute to gene expression. The results presented here provide a model system for significant enhancement of sulforaphane's potency with small molecule co-treatment., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Traumatic brain injury (TBI) affects 10 million people worldwide, annually. TBI is linked to increased risk of psychiatric disorders. TBI, induced by explosive devices, has a unique phenotype. Over one-third of people exposed to blast-induced TBI (bTBI) have prolonged neuroendocrine deficits, shown by anterior pituitary dysfunction. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is linked to increased risk for psychiatric disorders. Not only is there limited information on how the HPA axis responds to mild bTBI (mbTBI), sex differences are understudied. We examined central and peripheral HPA axis reactivity, 7 to 10 days after mbTBI in male and female mice. Males exposed to mbTBI had increased restraint-induced serum corticosterone (CORT), but attenuated restraint-induced corticotropin-releasing factor (CRF)/c-Fos-immunoreactivity (ir) in the paraventricular nucleus of the hypothalamus (PVN). Females displayed an opposite response, with attenuated restraint-induced CORT and enhanced restraint-induced PVN CRF/c-Fos-ir. We examined potential mechanisms underlying this dysregulation and found that mbTBI did not affect pituitary (pro-opiomelanocortin and CRF receptor subtype 1) or adrenal (11β-hydroxylase, 11β-dehydrogenase 1, and melanocortin 2 receptor) gene expression. mbTBI did not alter mineralocorticoid or glucocorticoid gene expression in the PVN or relevant limbic structures. In females, but not males, mbTBI decreased c-Fos-ir in non-neuroendocrine (presumably preautonomic) CRF neurons in the PVN. Whereas we demonstrated a sex-dependent link to stress dysregulation of preautonomic neurons in females, we hypothesize that mbTBI may disrupt limbic pathways involved in HPA axis coordination in males. Overall, mbTBI altered the HPA axis in a sex-dependent manner, highlighting the importance of developing therapies to target individual strategies that males and females use to cope with mbTBI.

Gonadotropin-releasing hormone (GnRH) neurons originate outside the central nervous system (CNS) in the nasal placode where their migration to the basal forebrain is dependent on the integration of multiple signaling cues during development. The proper migration and establishment of the GnRH neuronal population within the CNS are critical for normal pubertal onset and reproductive function. The endopeptidase EP24.15 is expressed along the migratory path of GnRH neurons and cleaves the full-length GnRH to generate the metabolite GnRH-(1-5). Using the GN11 cell model, which is considered a pre-migratory GnRH neuronal cell line, we demonstrated that GnRH-(1-5) inhibits cellular migration in a wound closure assay by binding the orphan G protein-coupled receptor 173 (GPR173). In our current experiments, we sought to utilize an in vitro migration assay that better reflects the external environment that migrating GnRH neurons are exposed to during development. Therefore, we used a transwell assay where the inserts were coated with or without a matrigel, a gelatinous mixture containing extracellular matrix (ECM) proteins, to mimic the extracellular environment. Interestingly, GnRH-(1-5) inhibited the ability of GN11 cells to migrate only through ECM mimetic and was dependent on GPR173. Furthermore, we found that GN11 cells secrete TGF-β1, 2, and 3 but only TGF-β1 release and signaling were inhibited by GnRH-(1-5). To identify potential mechanisms involved in the proteolytic activation of TGF-β, we measured a panel of genes implicated in ECM remodeling. We found that GnRH-(1-5) consistently increased tissue inhibitors of metalloproteinase 1 expression, which is an inhibitor of proteinase activity, leading to a decrease in bioactive TGF-β and subsequent signaling. These results suggest that GnRH-(1-5) activating GPR173 may modulate the response of migrating GnRH neurons to external cues present in the ECM environment via an autocrine-dependent mechanism involving TGF-β.

Gonadotropin-releasing hormone (GnRH) is a key regulatory molecule of the hypothalamus-pituitary (PIT)-gonadal (HPG) axis that ultimately leads to the downstream release of estradiol (E 2 ) and progesterone (P). These gonadal steroids feed back to the hypothalamus and PIT to regulate reproductive function and behavior. While GnRH is thought to be the master regulator of reproduction, its metabolic product GnRH-(1-5) is also biologically active. Thimet oligopeptidase 1 (also known as EP24.15) cleaves GnRH to form GnRH-(1-5). GnRH-(1-5) is involved in regulation of the HPG axis, exerting its actions through a pair of orphan G protein-coupled receptors, GPR101 and GPR173. The physiological importance of GnRH-(1-5) signaling has been studied in several contexts, but its potential role during reproductive senescence is poorly understood. We used an ovariectomized (OVX) rat model of reproductive senescence to assess whether and how GnRH-(1-5) signaling genes in hypothalamic subnuclei change in response to aging and/or different estradiol replacement regimens designed to model clinical hormone replacement in women. We found that Gpr101 and Gpr173 mRNA expression was increased with age in the arcuate nucleus, while expression of Gpr173 and EP24.15 increased with age in the medial preoptic area. Treatment with E 2 in younger OVX animals increased expression of Gpr101, Gpr173 , and EP24.15 . However, older animals treated with E 2 showed decreased expression of these GnRH-(1-5) signaling genes, displaying an age-related decline in responsiveness to E 2 . To our knowledge, this is the first study to systematically assess the effects of age and different clinically relevant regimens of E 2 replacement on GnRH-(1-5) signaling genes.