Calcium signalling in T cells

A Novel Compound 3a-M1, from Metabolites of Sinomenine Derivative 3a, Exerts Potent Anti-Aplastic Anemia Activity via IP3R/ORAI-Mediated CTL Ferroptosis

Aplastic anemia (AA) is a refractory hematological disease with limited therapeutic effectiveness and serious treatment-related side effects. Cytotoxic T lymphocytes (CTLs) play a key role in AA pathogenesis. In our previous study, sinomenine derivative 3a was obtained, which demonstrated potential anti-AA activity by targeting CTLs with low toxicity. In this study, a novel metabolite, 3a-M1, was identified with optimized bioavailability from 3a metabolism, which exhibited a more notable effect in alleviating anemia symptoms, suppressing bone marrow CTLs activation, and improving hematopoietic function in immune-mediated bone marrow failure mouse models. In vitro experiments demonstrated that 3a-M1 directly inhibited CTLs activation and their killing function; the underlying mechanism was at least in part mediated by the selective ferroptosis of overactivated CTLs via the IP3R/ORAI pathway. These findings suggest that 3a-M1 represents a novel potential therapeutic agent for AA treatment and ferroptosis may serve as a promising target on CTLs for AA therapy.

Cholinergic T cells revitalize the tumor immune microenvironment: TIME to ChAT

Crosstalk between the nervous system and the immune system shapes the tumor microenvironment. Cholinergic T cells, a unique population of T cell antigen receptor-induced acetylcholine-producing T cells, have emerged as an integrative interface between these two fundamental body systems. Here we review the distinct characteristics and functions of cholinergic T cells in cancer settings. We first outline the expression of choline acetyltransferase and the cholinergic machinery in T cells. We then describe the dysfunctional state of choline acetyltransferase-expressing T cells in cancer and delve into their modulatory effects on T cells, cancer cells and the tumor microenvironment, including its populations of immune cells, its vasculature and its nerves. We also discuss the clinical implications of harnessing the potential of cholinergic T cells and future directions for increasing our understanding of their importance and possible exploitation.

Metal-modulated T cell antitumor immunity and emerging metalloimmunotherapy

In recent years, increasing evidence has shown that metals play important roles in both innate and adaptive immunity. An emerging concept of metalloimmunotherapy has been proposed, which may accelerate the development of immunotherapy for cancers. Here, we discuss how metals affect T cell function through different signaling pathways. Metals impact the fate of T cells, including their activation, proliferation, cytotoxicity, and differentiation. Most importantly, metals also participate in mitochondrial operation by regulating energy production and reactive oxygen species homeostasis in T cells. We also identified the metal-based mutual effects between tumor cells and T cells in the tumor microenvironment. Overall, the antitumor effect of T cells can be improved by targeting metal metabolism and metalloimmunotherapy, which will be a step forward in the treatment of cancers.

T Lymphocyte Integrated Endoplasmic Reticulum Ca2+ Store Signaling Functions Are Linked to Sarco/Endoplasmic Reticulum Ca2+-ATPase Isoform-Specific Levels of Regulation

We explored the effects of altering expression levels of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) ion-transporting enzymes on key T lymphocyte signaling functions. In these studies, we have taken advantage of the Jurkat T cell line which provides a T lymphocyte model cell phenotype with a well-characterized T cell receptor (TCR)-activated signaling pathway, as well as offering a cellular system with a good understanding of the SERCA expression profile. These studies have been prompted by a strong imperative to gain a better understanding of the complex roles SERCA Ca2+ pumps play in the integrated TCR-activated signaling network, particularly given the central role of SERCA functions in regulating essential endoplasmic reticulum (ER) integrity. We find in this study that altering SERCA expression can significantly reconfigure ER Ca2+ stores, increasing or decreasing Ca2+ storage capacity depending on upregulation or downregulation of SERCA expression, and these effects are also associated with substantial changes in agonist-induced Ca2+ release and influx patterns. Not surprisingly, these fundamental changes in TCR-regulated Ca2+ signaling properties are associated with major alterations in T lymphocyte functions including regulation of growth patterns, cytokine secretion and energy utilization. Our study also describes additional evidence revealing intriguing functional distinctions between the major SERCA isoform-regulated Ca2+ stores in T lymphocytes. Our work thus serves to reinforce increasing efforts to target the SERCA pumps as a potential profitable strategy to produce novel engineered T lymphocytes in the rapidly growing field of T-cell immunotherapy.

Zinc Ion-Coordinated Sericin Calcium Phosphate Nanovaccines Induce Hyperactive Dendritic Cells and Synergistic Activation of T Cells for Cancer Immunotherapy

Peptide-based neoantigen vaccines are promising cancer immunotherapy strategies because of their capability to induce durable tumor-specific immune responses. However, insufficient neoantigen-specific T-lymphocyte activation greatly limits their clinical efficacy. Here, we developed sericin-coordinated zinc ion-modified calcium phosphate (CP) nanovaccines that codeliver tumor antigen peptides and a Toll-like receptor 9 agonist (SZCP/APs-CpG) for potentiating antigen-specific T cell immunity. SZCP/APs-CpG nanovaccines could yield efficient codelivery of antigen peptides and adjuvants to dendritic cells (DCs) in draining lymph nodes (dLNs), induce hyperactive DCs depending on the inflammasome-dependent interleukin-1β secretion, and coordinate the released Zn2+-induced T cell activation to elicit robust and durable antigen-specific T cell immune responses. Vaccination with SZCP/APs-CpG exhibited potent anticancer efficacy and superior safety in multiple murine cancer models and significantly protected against B16-OVA tumor rechallenge and eradicated orthotopic colon cancer in mice when combined with immune checkpoint blockade. Thus, our work presents an efficient and versatile nanovaccine platform for boosting antigen-specific T cell activation for cancer immunotherapy.

Explosive cytotoxicity of 'ruptoblasts' bridges hormonal surveillance and immune defense

Cytotoxic killing is an essential immune function, yet its cellular mechanisms have been characterized in only a few model species. Here, we show that planarian flatworms harness a unique cytotoxic strategy. In planarians, activin, a hormone regulating regeneration and reproduction, also acts as an inflammatory cytokine. Overactivation of activin signaling - through protein injection, genetic chimerism, or bacterial infection - triggers 'ruptoblasts', an undocumented immune cell type, to undergo 'ruptosis', a unique mode of cell bursting that eliminates nearby cells and bacteria in mere minutes, representing one of the fastest cytotoxic mechanisms observed. Ablating ruptoblasts suppresses inflammation but compromises bacterial clearance, highlighting ruptoblasts' broad-spectrum immune functions. We further identified ruptoblast-like cells in diverse basal bilaterians, unveiling an alternative strategy that couples hormonal regulation with immune defense and expanding the landscape of evolutionary immune innovations.

A Single-Cell Atlas of RNA Alternative Splicing in the Glioma-Immune Ecosystem

Single-cell analysis has refined our understanding of cellular heterogeneity in glioma, yet RNA alternative splicing (AS)-a critical layer of transcriptome regulation-remains underexplored at single-cell resolution. Here, we present a pan-glioma single-cell AS analysis in both tumor and immune cells through integrating seven SMART-seq2 datasets of human gliomas. Our analysis reveals lineage-specific AS across glioma cellular states, with the most divergent AS landscapes between mesenchymal- and neuronal-like glioma cells, exemplified by AS in TCF12 and PTBP2. Comparison between core and peripheral glioma cells highlights AS-redox co-regulation of cytoskeleton organization. Further analysis of glioma-infiltrating immune cells reveals potential isoform-level regulation of protein glycosylation in regulatory T cells and a link between MS4A7 AS in macrophages and clinical response to anti-PD-1 therapy. This study emphasizes the role of AS in glioma cellular heterogeneity, highlighting the importance of an isoform-centric approach to better understand the complex biological processes driving tumorigenesis.

Anoctamin 9 determines Ca2+ signals during activation of T-lymphocytes

Background

Activation of T-cells is initiated by an increase in intracellular Ca2+, which underlies positive and negative regulation. Because the phospholipid scramblase and ion channel ANO9 (TMEM16J) was shown previously to regulated Ca2+ signals in renal epithelial cells, we asked whether ANO9 demonstrates a similar regulation in T-cells.

Methods

We used measurements of the intracellular Ca2+ concentration to examine the effects of ANO9 on intracellular Ca2+ signaling and demonstrated expression of ANO9 and its effects on cellular and molecular parameters.

Results

ANO9 was found to be expressed in human lymphocytes, including the Jurkat T-lymphocyte cell line and mouse lymphocytes. ANO9 has been shown to affect intracellular Ca2+ signals in renal epithelial cells. Here we demonstrate the essential role of ANO9 during initiation of intracellular Ca2+ signals in Jurkat T-cells and isolated mouse lymphocytes. ANO9 is essential for the initial rise in intracellular Ca2+ due to influx of extracellular Ca2+ through store-operated ORAI1 Ca2+ entry channels. ANO9 is indispensable for T-cell function, independent on whether cells are activated by stimulation of the T-cell receptor with CD3-antibody or by PMA/phytohemagglutinin.

Conclusions

Upon activation of T-cells and formation of the immunological synapse, ANO9 recruits the Ca2+-ATPase (PMCA) to the plasma membrane, which is supported by the scaffolding protein discs large 1 (DLG1). PMCAs maintain low Ca2+ levels near ORAI1 channels thereby suppressing Ca2+-inhibition of ORAI1 and thus retaining store-operated Ca2+ entry (SOCE). It is suggested that ANO9 has a role in interorganelle communication and regulation of cellular protein trafficking, which probably requires its phospholipid scramblase function.

Sodium citrate pretreatment enhances CAR-T cell persistence and anti-tumor efficacy through inhibition of calcium signaling

Introduction

Chimeric antigen receptor T cell (CAR-T) therapy has shown success in treating hematological malignancies, but its effectiveness against solid tumors is hindered by T cell exhaustion. During in vitro expansion, tonic signaling induced by CAR expression contributes to CAR-T cell exhaustion, which can be mitigated by inhibiting calcium signaling. Given that sodium citrate can chelate calcium ions and inhibit calcium signaling, in this study, we investigated whether sodium citrate could reduce exhaustion and enhance CAR-T cell function.

Methods

We constructed anti-CD70 CAR-T cells and cultured them in the presence of sodium citrate. The characteristics and functionality of sodium citrate-pretreated CAR-T cells were assessed through in vitro and in vivo experiments. To further validate our observation, we also treated anti-mesothelin (MSLN) CAR-T cells with sodium citrate and detected the phenotypes and anti-tumor function of CAR-T cells.

Results

We found that sodium citrate-pretreated anti-CD70 CAR-T cells exhibited reduced exhaustion, increased memory T cell proportions, and enhanced anti-tumor efficacy both in vitro and in vivo. Notably, sodium citrate treatment improved the in vivo persistence of CAR-T cells and prevented tumor recurrence. These beneficial effects were also observed in anti-MSLN CAR-T cells. Transcriptomic and metabolite analyses revealed that sodium citrate inhibited calcium signaling, mTORC1 activity, and glycolysis pathways, thus modulating T cell exhaustion and differentiation.

Discussion

Our findings suggest that sodium citrate supplementation during CAR-T cell expansion could be a promising strategy to improve CAR-T therapy for solid tumors by preventing exhaustion and promoting memory T cell formation.

TMEM41B is an endoplasmic reticulum Ca2+ release channel maintaining naive T cell quiescence and responsiveness

In mammalian cells, endoplasmic reticulum (ER) passively releases Ca2+ under steady state, but channels involved remain elusive. Here, we report that TMEM41B, an ER-resident membrane protein critical for autophagy, lipid metabolism, and viral infection, functions as an ER Ca2+ release channel. Biochemically, purified recombinant TMEM41B forms a concentration-dependent Ca2+ channel in single-channel electrophysiology assays. Cellularly, TMEM41B deficiency causes ER Ca2+ overload, while overexpression of TMEM41B depletes ER Ca2+. Immunologically, ER Ca2+ overload leads to upregulation of IL-2 and IL-7 receptors in naive T cells, which in turn increases basal signaling of JAK-STAT, AKT-mTOR, and MAPK pathways. This dysregulation drives TMEM41B-deficient naive T cells into a metabolically activated yet immunologically naive state. ER Ca2+ overload also downregulates CD5, lowering the activation threshold of TMEM41B-deficient T cells and leading to heightened T cell responses during infections. In summary, we identify TMEM41B as a concentration-dependent ER Ca2+ release channel, revealing an unexpected role of ER Ca2+ in naive T cell quiescence and responsiveness.

Innateness transcriptome gradients characterize mouse T lymphocyte populations

A fundamental dichotomy in lymphocytes separates adaptive T and B lymphocytes, with clonally expressed antigen receptors, from innate lymphocytes, which carry out more rapid responses. Some T cell populations, however, are intermediates between these 2 poles, with the capacity to respond rapidly through T cell receptor activation or by cytokine stimulation. Here, using publicly available datasets, we constructed linear mixed models that not only define a gradient of innate gene expression in common for mouse innate-like T cells, but also are applicable to other mouse T lymphoid populations. A similar gradient could be identified for chromatin landscape based on ATAC-seq (assay for transposase-accessible chromatin using sequencing) data. The gradient included increased transcripts related to many traits of innate immune responses, with increased scores related to evidence for antigen experience. While including genes typical for T helper 1 (Th1) responses, the innateness gene program could be separated from Th1, Th2, and Th17 responses. Lymphocyte populations with higher innateness scores correlated with lower calcium-dependent T cell receptor-mediated cell activation, with some downstream signaling proteins dependent on calcium or affecting metabolism prephosphorylation. Therefore, as a group, different mouse innate-like T cell populations had related gene expression programs and activation pathways that are different from naive CD4 and CD8 T cells.

Sirt6, Deubiquitinated and Stabilised by USP9X, Takes Essential Actions on the Pathogenesis of Experimental Autoimmune Myasthenia Gravis by Regulating CD4+ T Cells

Myasthenia gravis (MG) presents with symptoms that significantly affect patients' daily lives. Long-term MG therapies may lead to substantial side effects, predominantly due to prolonged immune suppression. Sirt6, which plays a vital role in maintaining cellular homeostasis and is recognised for its involvement in cytokine production in immune cells, has not yet been explored in relation to MG. PBMCs and CD4+ T cells were isolated from blood samples. RT-qPCR, western blot and ELISA were used to assess the expression of target genes and proteins. Flow cytometry was used to identify the subsets of T helper cells. Co-IP was conducted to investigate the interaction between USP9X and Sirt6. Finally, the experimental autoimmune myasthenia gravis (EAMG) model was established. In MG patients, Sirt6 levels were downregulated compared to healthy controls. Sirt6 overexpression led to a reduction in Th1 and Th17 cell populations while augmenting Treg cells in PBMCs. USP9X interacted with Sirt6, leading to its deubiquitination and stabilisation. Elevated Sirt6 levels subsequently mitigated symptoms in the EAMG model. The stabilisation of Sirt6, mediated by USP9X, has been found to relieve symptoms of EAMG by influencing the subtypes of T helper cells. This highlights the promising potential of Sirt6 as a viable therapeutic target in the treatment of MG.

Towards a unifying model for B-cell receptor triggering

Antibodies are exceptionally versatile molecules with remarkable flexibility in their binding properties. Their natural targets range from small-molecule toxins, across viruses of different sizes, to bacteria and large multicellular parasites. The molecular determinants bound by antibodies include proteins, peptides, carbohydrates, nucleic acids, lipids and even synthetic molecules that have never existed in nature. Membrane-anchored antibodies also serve as receptors on the surface of the B cells that produce them. Despite recent structural insights, there is still no unifying molecular mechanism to explain how antibody targets (antigens) trigger the activation of these B-cell receptors (BCRs). After cognate antigen encounter, somatic hypermutation and class-switch recombination allow BCR affinity maturation and immunoglobulin class-specific responses, respectively. This raises the fundamental question of how one receptor activation mechanism can accommodate a plethora of variant receptors and ligands, and how it can ensure that individual B cells remain responsive to antigen after somatic hypermutation and class switching. There is still no definite answer. Here we give a brief historical account of the different models proposed to explain BCR triggering and discuss their merit in the context of the current knowledge of the structure of BCRs, their dynamic membrane distribution, and recent biochemical and cell biological insights.

Dominant negative variants in ITPR3 impair T cell Ca2+ dynamics causing combined immunodeficiency

The importance of calcium (Ca2+) as a second messenger in T cell signaling is exemplified by genetic deficiencies of STIM1 and ORAI1, which abolish store-operated Ca2+ entry (SOCE) resulting in combined immunodeficiency (CID). We report five unrelated patients with de novo missense variants in ITPR3, encoding a subunit of the inositol 1,4,5-trisphosphate receptor (IP3R), which forms a Ca2+ channel in the endoplasmic reticulum (ER) membrane responsible for the release of ER Ca2+ required to trigger SOCE, and for Ca2+ transfer to other organelles. The patients presented with CID, abnormal T cell Ca2+ homeostasis, incompletely penetrant ectodermal dysplasia, and multisystem disease. Their predominant T cell immunodeficiency is characterized by significant T cell lymphopenia, defects in late stages of thymic T cell development, and impaired function of peripheral T cells, including inadequate NF-κB- and NFAT-mediated, proliferative, and metabolic responses to activation. Pathogenicity is not due to haploinsufficiency, rather ITPR3 protein variants interfere with IP3R channel function leading to depletion of ER Ca2+ stores and blunted SOCE in T cells.

Imaging Protocol for Super-Resolution Microscopy in Fixed T Cells

Super-resolution microscopy has revolutionized the field of cellular imaging by overcoming the diffraction limit of conventional light microscopy and enabling the visualization of cellular structures in the nanometre range. In this protocol, a detailed procedure for super-resolution imaging of fixed primary murine T cells is described, focusing on preparation, staining, and post-processing. Imaging is performed using a super-resolution stimulated emission depletion (STED) microscope with a confocal laser scanning unit. After imaging, the data is processed using deconvolution and segmentation to reconstruct high-resolution images that enable detailed analysis of the T cell structures. This method enables a deeper understanding of T cell biology by revealing the intricate details of their internal organization and interactions.

Imaging BiTE-Mediated Activation of Primary Human CD8+ T Cells

CD8+ T cells are a vital branch of the adaptive immune response. They are necessary for an effective antiviral and anticancer immunity, which is mediated through their cytotoxic effector functions. CD8+ T cell activation, proliferation, and effector functions are dependent on a complex network of Ca2+ signalling pathways involving both Ca2+ release and Ca2+ entry. Dysregulation of intracellular Ca2+ signalling pathways has been linked to immunodeficiencies including severe combined immunodeficiency syndrome (SCID), highlighting the need to study both Ca2+ dynamics and cytotoxic effector function in patient-derived CD8+ T cells. The following protocol describes a workflow for the isolation of primary human CD8+ T cells and their activation using bispecific T cell engagers (BiTEs). This allows for a simultaneous assessment of both Ca2+ dynamics and cytotoxicity through a target cell line presenting an epitope recognized by the BiTE.

Analysis of Store-Operated Ca2+ Entry in Primary T Cells

Calcium ions (Ca2+) are key second messengers for signal transduction in virtually all cells. In T cells, Ca2+ signals are generated upon T cell receptor (TCR) stimulation in a two-step integrated process known as Store-Operated Ca2+ Entry (SOCE), which involves the depletion of endoplasmic reticulum (ER) Ca2+ stores, followed by the influx of extracellular Ca2+ via Ca2+ release-activated Ca2+ (CRAC) channels. The Ca2+ influx generated by the opening of CRAC channels in T cells is essential for their metabolic reprogramming, proliferation, cytokine production, and adaptive immune response.In this book chapter, we review general concepts, discuss the rationale for using ratiometric Ca2+-sensitive chemical dyes to monitor SOCE in primary murine T cells, and weigh the advantages and disadvantages of the different methods that are currently available to detect cytosolic Ca2+ dynamics. We provide detailed protocols to measure SOCE in mouse T cells including flow cytometry, fluorescent microplate reader and single-cell imaging, and offer a general guideline on how to quantify SOCE in these cells. These protocols are easily adaptable to monitor cytosolic Ca2+ dynamics in human T cells and other cell types of interest.

High intracellular calcium amounts inhibit activation-induced proliferation of mouse T cells: Tert-butyl hydroquinone as an additive enhancer of intracellular calcium

Optimal T cell activation is critical to orchestrate adaptive immune responses. Calcium is critical for T cell activation and integrates signaling pathways necessary to activate key transcription factors. In fact, patients with calcium channelopathies are immunodeficient. Here, we investigated the effects of different concentrations of intracellular calcium on activation of mouse T cells. High intracellular calcium amounts inhibited in vitro T cell proliferation as evidenced by a decreased cell cycling-to-hypodiploidy ratio in two models of activation: the combination of phorbol 12-myristate 13-acetate (PMA) and Ionomycin (an ionophore)/Thapsigargin (a SERCA inhibitor) or plate bound anti-CD3 and anti-CD28. High intracellular calcium amounts increased the production of reactive oxygen species (ROS) in T cells activated with PMA and Ionomycin and scavenging excess ROS using N-acetyl cysteine (NAC) rescued the decrease in cycling-to-hypodiploidy ratio. To test the universality of our observations, we studied the effects of tert-Butylhydroquinone (tBHQ), a SERCA inhibitor and Nrf2 activator. tBHQ alone did not increase intracellular calcium amounts but the intracellular calcium amounts increased when tBHQ was used in combination with PMA. Also, tBHQ inhibited T cell activation in a dose-dependent manner in both in vitro models of T cell activation. Importantly, intraperitoneal injection of tBHQ ameliorated Dextran Sodium Sulfate (DSS)-induced colitis in mice as evidenced by rescue of colon length shortening and lower disease activity index. Overall, this study identifies high calcium amounts as a potential target to lower T cell activation. The implications of these observations are discussed in the context of calcium modulating drugs that are used to treat various diseases.

Metabolic immunoengineering approaches to enhance CD8+ T cell-based cancer immunotherapy

Many cancer immunotherapies rely on robust CD8+ T cells capable of eliminating cancer cells and establishing long-term tumor control. Recent insights into immunometabolism highlight the importance of nutrients and metabolites in T cell activation and differentiation. Within the tumor microenvironment (TME), CD8+ tumor-infiltrating lymphocytes (TILs) undergo metabolic adaptations to survive but compromise their effector function and differentiation. Targeting metabolism holds promise for enhancing CD8+ T cell-mediated antitumor immunity. Here, we overview the metabolic features of CD8+ TILs and their impact on T cell effector function and differentiation. We also highlight immunoengineering strategies by leveraging the Yin-Yang of metabolic modulation for improving cancer immunotherapy.

Calcium dynamics of skin-resident macrophages during homeostasis and tissue injury

Immune cells depend on rapid changes in intracellular calcium activity to modulate cell function. Skin contains diverse immune cell types and is critically dependent on calcium signaling for homeostasis and repair, yet the dynamics and functions of calcium in skin immune cells remain poorly understood. Here, we characterize calcium activity in Langerhans cells, skin-resident macrophages responsible for surveillance and clearance of cellular debris after tissue damage. Langerhans cells reside in the epidermis and extend dynamic dendrites in close proximity to adjacent keratinocytes and somatosensory peripheral axons. We find that homeostatic Langerhans cells exhibit spontaneous and transient changes in calcium activity, with calcium flux occurring primarily in the cell body and rarely in the dendrites. Triggering somatosensory axon degeneration increases the frequency of calcium activity in Langerhans cell dendrites. By contrast, we show that Langerhans cells exhibit a sustained increase in intracellular calcium following engulfment of damaged keratinocytes. Altering intracellular calcium activity leads to a decrease in engulfment efficiency of keratinocyte debris. Our findings demonstrate that Langerhans cells exhibit context-specific changes in calcium activity and highlight the utility of skin as an accessible model for imaging calcium dynamics in tissue-resident macrophages.

Ca2+ puffs underlie adhesion-triggered Ca2+ microdomains in T cells

Ca2+ signalling is pivotal in T cell activation, an essential process in adaptive immune responses. Key to this activation are Ca2+ microdomains, which are transient increases in cytosolic Ca2+ concentration occurring within narrow regions between the endoplasmic reticulum (ER) and the plasma membrane (PM), lasting a few tens of milliseconds. Adhesion Dependent Ca2+ Microdomains (ADCM) rely on store-operated Ca2+ entry (SOCE) via the ORAI/STIM system. The nanometric scale at which these microdomains form poses challenges for direct experimental observation. Following the previous work of Gil et al. [1], which introduced a three-dimensional model of the ER-PM junction, this study combines a detailed description of the Ca2+ fluxes at the junction with stochastic dynamics of a cluster of D-myo-inositol 1,4,5 trisphosphate receptors (IP3R) located in the ER surrounding the junction. Because the consideration of Ca2+ release through the IP3R calls for the simulation of a portion of the cytoplasm considerably larger than the junction, our study also investigates the spatial distribution of PMCAs, revealing their likely localization outside the ER-PM junction. Simulations indicate that Ca2+ puffs implying the opening of 2-6 IP3Rs create ADCMs by provoking local depletions of ER Ca2+ stimulating Ca2+ entry through the ORAI1 channels. Such conditions allow the reproduction of the amplitude, duration and spatial extent of the observed ADCMs. By integrating advanced computational techniques with insights from experimental studies, our approach provides valuable information on the mechanisms governing early Ca2+ signalling in T cell activation, paving the way for a deeper understanding of immune responses.

Modeling immune checkpoint inhibitor associated myocarditis in vitro and its therapeutic implications

Immune checkpoint inhibitor-associated myocarditis is the most lethal side effect of immune checkpoint blockade. Myocarditis leads to persistently increased mortality and lacks effective treatments. The development of patient-relevant disease models may enable disease prediction, increased understanding of disease pathophysiology, and the development of effective treatment strategies. Here, we report a new method to model immune checkpoint inhibitor-associated myocarditis in vitro via a co-culture of activated primary human immune cells, human induced pluripotent stem cell-derived cardiomyocytes, and FDA-approved immune checkpoint inhibitors to recapitulate myocarditis in vitro. Significant cardiomyocyte necrosis, arrhythmia development, and sarcomere destruction occur, replicating clinical findings from myocarditis. This tissue culture myocarditis phenotype may rely on an induced pluripotent stem cell-derived cardiomyocyte antigen-specific CD8+ T cell response. The administration of dexamethasone rescued cardiomyocyte viability, morphology, and electrophysiology and suppressed inflammatory cytokine production. In conclusion, we detail how this platform can effectively model and provide critical information about the morphological and electrophysiological changes induced by immune checkpoint inhibitor-associated myocarditis. We have also validated the ability of this platform to screen potential medications to treat immune checkpoint inhibitor-associated myocarditis. This work establishes a robust, scalable model for identifying new therapies and risk factors, which is valuable in delineating the nature of interactions between the immune system and the heart during myocarditis.

Deficiency in the mitophagy mediator Parkin accelerates murine skin allograft rejection

Alterations in mitochondrial function and associated quality control programs, including mitochondrial-specific autophagy, termed mitophagy, are gaining increasing recognition in the context of disease. However, the role of mitophagy in organ transplant rejection remains poorly understood. Using mice deficient in Parkin, a ubiquitin ligase that tags damaged or dysfunctional mitochondria for autophagic clearance, we assessed the impact of Parkin-dependent mitophagy on skin-graft rejection. We observed accelerated graft loss in Parkin-deficient mice across multiple skin graft models. Immune cell distributions posttransplant were largely unperturbed compared to wild-type; however, the CD8+ T cells of Parkin-deficient mice expressed more T-bet, IFNγ, and Ki67, indicating greater priming toward effector function. This was accompanied by increased circulating levels of IL-12p70 in Parkin-deficient mice. Using a mixed leukocyte reaction, we demonstrated that naïve Parkin-deficient CD4+ and CD8+ T cells exhibit enhanced activation marker expression and proliferative responses to alloantigen, which were attenuated with administration of a pharmacological mitophagy inducer (p62-mediated mitophagy inducer), known to increase mitophagy in the absence of a functional PINK1-Parkin pathway. These findings indicate a role for Parkin-dependent mitophagy in curtailing skin-graft rejection.

Anti-microbial cetylpyridinium chloride suppresses mast cell function by targeting tyrosine phosphorylation of Syk kinase

Cetylpyridinium chloride (CPC) is a quaternary ammonium antimicrobial used in numerous personal care products, human food, cosmetic products, and cleaning solutions. Yet, there is minimal published data on CPC effects on eukaryotes, immune signaling, and human health. Previously, it was shown that low-micromolar CPC inhibits rat mast cell function by inhibiting antigen (Ag)-stimulated Ca2+ mobilization, microtubule polymerization, and degranulation. In the current study, these findings are extended to human mast cells (LAD2); this paper presents data indicating that a mechanism of action for CPC might center on its positively-charged quaternary nitrogen in its pyridinium headgroup. The inhibitory effect of CPC was independent of signaling platform receptor architecture. Tyrosine phosphorylation events are a trigger of Ca2+ mobilization necessary for degranulation. CPC inhibits global tyrosine phosphorylation in Ag-stimulated mast cells. Specifically, CPC inhibits tyrosine phosphorylation of specific key players Syk kinase and LAT, a substrate of Syk. In contrast, CPC did not affect Lyn kinase phosphorylation. Thus, a root mechanism for CPC effect might be electrostatic disruption of particular tyrosine phosphorylation events essential for signaling. This work presented here outlines biochemical mechanisms underlying the effects of CPC on immune signaling.

Calcium nanoparticles target and activate T cells to enhance anti-tumor function

Calcium signaling plays a crucial role in the activation of T lymphocytes. However, modulating calcium levels to control T cell activation in vivo remains a challenge. In this study, we investigate T cell activation using 12-myristate 13-acetate (PMA)-encapsulated CaCO3 nanoparticles. We find that anti-PD-1 antibody-conjugated CaCO3 nanoparticles can be internalized by T cells via receptor-mediated endocytosis and then gradually release calcium. This results in an increase in cytosolic calcium, which triggers the activation of NFAT and NF-κB pathways, especially when the surface of the CaCO3 nanoparticles is loaded with PMA. Animal studies demonstrate that the PMA-loaded calcium nanoparticles enhance the activation and proliferation of cytotoxic T cells, leading to improved tumor suppression without additional toxicity. When tested in metastatic tumor models, T cells loaded with the calcium nanoparticles prior to adoptive cell transfer control tumor growth better, resulting in prolonged animal survival. Our approach offers an alternative T cell activation strategy to potentiate immunotherapy by targeting a fundamental signaling pathway.

An early, novel arginine methylation of KCa3.1 attenuates subsequent T cell exhaustion

T cell receptor (TCR) engagement initiates the activation process, and this signaling event is regulated in multifaceted ways. Nutrient availability in the immediate niche is one such mode of regulation 1-3 . Here, we investigated how the availability of an essential amino acid methionine (Met) and TCR signaling might interplay in the earliest events of T cell activation to affect subsequent T cell fate and function. We found that limiting Met during only the initial 30 minutes of CD8 + T cell activation increased Ca 2+ influx, Ca 2+ -mediated NFAT1 ( Nfatc2 ) activation, NFAT1 promoter occupancy, and T cell exhaustion. We identified changes in the protein arginine methylome during the initial 30 min of TCR engagement and discovered a novel arginine methylation of a Ca 2+ -activated potassium transporter, KCa3.1, which regulates Ca 2+ -mediated NFAT1 signaling to ensure optimal activation. Ablation of arginine methylation in KCa3.1 led to increased NFAT1 activation, rendering T cells dysfunctional in murine tumour and infection models. Furthermore, acute Met supplementation at early stages reduced nuclear NFAT1 in tumour-infiltrating T cells and augmented their anti-tumour activity. Our findings identify a metabolic event occurring early after T cell activation that influences the subsequent fate of the cell.

Into the deep: Exploring the molecular mechanisms of hyperactive behaviour induced by three rare earth elements in early life-stages of the deep-sea scavenging amphipod Tmetonyx cicada (Lysianassidae)

With increasing socio-economic importance of the rare earth elements and yttrium (REY), Norway has laid out plans for REY mining, from land-based to deep-sea mining, thereby enhancing REY mobility in the marine ecosystem. Little is known about associated environmental consequences, especially in the deep ocean. We explored the toxicity and modes of action of a light (Nd), medium (Gd) and heavy (Yb) REY-Cl3 at four concentrations (3, 30, 300, and 3000 μg L-1) in the Arcto-boreal deep-sea amphipod Tmetonyx cicada. At the highest concentration, REY solubility was limited and increased with atomic weight (Nd < Gd < Yb). Lethal effects were practically restricted to this treatment, with the lighter elements being more acutely toxic than Yb (from ∼50 % mortality in the Gd-group at dissolved 689-504 μg L-1 to <20 % in the Yb-group at ca. 2000 μg L-1), which could be a function of bioavailability. All three REY induced hyperactivity at the low-medium concentrations. Delving into the transcriptome of T. cicada allowed us to determine a whole array of potential (neurotoxic) mechanisms underlying this behaviour. Gd induced the vastest response, affecting serotonin-synthesis; sphingolipid-synthesis; the renin-angiotensin system; mitochondrial and endoplasmic reticulum functioning (Gd, Nd); and lysosome integrity (Gd, Yb); as well as the expression of hemocyanin, potentially governing REY-uptake (Gd, Yb). While Nd and Yb shared only few pathways, suggesting a link between mode of action and atomic weight/radius, almost all discussed mechanisms imply the disruption of organismal Ca-homeostasis. Despite only fragmental genomic information available for crustaceans to date, our results provide novel insight into the toxicophysiology of REY in marine biota. The neurotoxic/behavioural effects in T. cicada at concentrations with potential environmental relevance warn about the possibility of bottom-up ecological consequences in mining exposed fjords and deep-sea ecosystems, calling for follow-up studies and regulatory measures prior to the onset of REY mining in Norway.

Kaempferol regulating macrophage foaming and atherosclerosis through Piezo1-mediated MAPK/NF-κB and Nrf2/HO-1 signaling pathway

INTRODUCTION

Antioxidants represented by kaempferol have been shown to be effective against atherosclerosis (AS). However, the underlying mechanisms still remain unclear.

OBJECTIVES

The aim of this research was to reveal the mechanism of kaempferol regarding the treatment of AS and accumulation of foam cell.

METHODS

We explored the contribution of kaempferol to the levels of inflammatory factors, scavenger receptor CD36, mitochondrial membrane potential, ROS, MAPK/NF-κB, Nrf2/HO-1, Ca2+ and Piezo1 levels in RAW264.7 macrophages exposed to ox-LDL. In addition, to explore whether kaempferol inhibits ox-LDL-induced foamy macrophage through Piezo1, we extracted macrophages from Piezo1 macrophage-specific knockout (Piezo1ΔLysM) mice. For further validation, ApoE-/- and Piezo1 macrophage-specific knockout mice (Piezo1ΔLysM/ ApoE-/-) were generated.

RESULTS

The results showed that kaempferol notably suppressed inflammatory response, CD36 expression, mitochondrial membrane potential elevation, ROS production, MAPK/NF-κB expression, Ca2+ influx, and increased Nrf2/HO-1 levels in RAW264.7. In addition, depletion of macrophage Piezo1 also effectively reduced lipid droplet deposition, inflammatory factor expression, oxidative damage, MAPK/NF-κB, Ca2+ influx, and increased Nrf2/HO-1 expression in mouse BMDMs, and the results were still consistent after kaempferol treatment. In vivo studies have shown that kaempferol significantly reduces atherosclerotic plaque formation. However, the beneficial effect of kaempferol was attenuated in Piezo1 depletion mice.

CONCLUSIONS

These results collectively provide compelling evidence that kaempferol regulates CD36-mediated mitochondrial ROS production by inhibiting the Piezo1 channels and Ca2+ influx, and then regulates the downstream pathways of NF-κB/MAPK and HO-1/Nrf2, inhibiting to the formation of foam cells. In conclusion, this study revealed a potential mechanism by which the natural antioxidant kaempferol prevents foamy macrophage.

EF-hand calcium sensor, EfhP, controls transcriptional regulation of iron uptake by calcium in Pseudomonas aeruginosa

The human pathogen Pseudomonas aeruginosa (Pa) poses a major risk for a range of severe infections, particularly lung infections in patients suffering from cystic fibrosis (CF). As previously reported, the virulent behavior of this pathogen is enhanced by elevated levels of Ca2+ that are commonly present in CF nasal and lung fluids. In addition, a Ca2+-binding EF-hand protein, EfhP (PA4107), was partially characterized and shown to be critical for the Ca2+-regulated virulence in P. aeruginosa. Here, we describe the rapid (10 min, 60 min), and adaptive (12 h) transcriptional responses of PAO1 to elevated Ca2+ detected by genome-wide RNA sequencing and show that efhP deletion significantly hindered both rapid and adaptive Ca2+ regulation. The most differentially regulated genes included multiple Fe sequestering mechanisms, a large number of extracytoplasmic function sigma factors (ECFσ), and several virulence factors, such as the production of pyocins. The Ca2+ regulation of Fe uptake was also observed in CF clinical isolates and appeared to involve the global regulator Fur. In addition, we showed that the efhP transcription is controlled by Ca2+ and Fe, and this regulation required a Ca2+-dependent two-component regulatory system CarSR. Furthermore, the efhP expression is significantly increased in CF clinical isolates and upon pathogen internalization into epithelial cells. Overall, the results established for the first time that Ca2+ controls Fe sequestering mechanisms in P. aeruginosa and that EfhP plays a key role in the regulatory interconnectedness between Ca2+ and Fe signaling pathways, the two distinct and important signaling pathways that guide the pathogen's adaptation to the host.IMPORTANCEPseudomonas aeruginosa (Pa) poses a major risk for severe infections, particularly in patients suffering from cystic fibrosis (CF). For the first time, kinetic RNA sequencing analysis identified Pa rapid and adaptive transcriptional responses to Ca2+ levels consistent with those present in CF respiratory fluids. The most highly upregulated processes include iron sequestering, iron starvation sigma factors, and self-lysis factors pyocins. An EF-hand Ca2+ sensor, EfhP, is required for at least 1/3 of the Ca2+ response, including the majority of the iron uptake mechanisms and the production of pyocins. Transcription of efhP itself is regulated by Ca2+ and Fe, and increases during interactions with host epithelial cells, suggesting the protein's important role in Pa infections. The findings establish the regulatory interconnectedness between Ca2+ and iron signaling pathways that shape Pa transcriptional responses. Therefore, understanding Pa's transcriptional response to Ca2+ and associated regulatory mechanisms will serve in the development of future therapeutics targeting Pa's dangerous infections.

SERCA Modulators Reveal Distinct Signaling and Functional Roles of T Lymphocyte Ca2+ Stores

The allosteric SERCA (Sarcoplasmic/Endoplasmic Reticulum Ca2+-ATPase) activator CDN1163 has been recently added to the group of pharmacological tools for probing SERCA function. We chose to investigate the effects of the compound on T lymphocyte Ca2+ stores, using the well-described Jurkat T lymphocyte as a reliable cell system for Ca2+ signaling pathways. Our study identified the lowest concentrations of the SERCA inhibitors thapsigargin (TG) and 2,5-di-(tert butyl)-1,4-benzohydroquinone (tBHQ) capable of releasing Ca2+, permitting the differentiation of the TG-sensitive SERCA 2b Ca2+ store from the tBHQ-sensitive SERCA 3 Ca2+ store. We proceeded to test the effects of CDN1163 on Ca2+ stores, examining specific actions on the SERCA 2b and SERCA 3 Ca2+ pools using our low-dose SERCA blocker regimen. In contrast to previous work, we find CDN1163 exerts complex time-sensitive and SERCA isoform-specific actions on Ca2+ stores. Surprisingly, short-term exposure (0-30 min) to CDN1163 perturbs T cell Ca2+ stores by suppressing Ca2+ uptake with diminished Ca2+ release from the SERCA 2b-controlled store. Concomitantly, we find evidence for a SERCA-activating effect of CDN1163 on the SERCA-3 regulated store, given the observation of increased Ca2+ release inducible by low-dose tBHQ. Intriguingly, longer-term (>12 h) CDN1163 exposure reversed this pattern, with increased Ca2+ release from SERCA 2b-regulated pools yet decreased Ca2+ release responses from the tBHQ-sensitive SERCA 3 pool. Indeed, this remodeling of SERCA 2b Ca2+ stores with longer-term CDN1163 exposure also translated into the compound's ability to protect Jurkat T lymphocytes from TG but not tBHQ-induced growth suppression.

Metabolic and ionic control of T cells in asthma endotypes

CD4+ T cells play a central role in orchestrating the immune response in asthma, with dysregulated ion channel profiles and altered metabolic signatures contributing to disease progression and severity. An important classification of asthma is based on the presence of T-helper cell type 2 (Th2) inflammation, dividing patients into Th2-high and Th2-low endotypes. These distinct endotypes have implications for disease severity, treatment response, and prognosis. By elucidating how ion channels and energy metabolism control Th cells in asthma, this review contributes to the pathophysiological understanding and the prospective development of personalized therapeutic treatment strategies for patients suffering from distinct asthma endotypes.

Rap1A Modulates Store-Operated Calcium Entry in the Lung Endothelium: A Novel Mechanism Controlling NFAT-Mediated Vascular Inflammation and Permeability

BACKGROUND

Store-operated calcium entry mediated by STIM (stromal interaction molecule)-1-Orai1 (calcium release-activated calcium modulator 1) is essential in endothelial cell (EC) functions, affecting signaling, NFAT (nuclear factor for activated T cells)-induced transcription, and metabolic programs. While the small GTPase Rap1 (Ras-proximate-1) isoforms, including the predominant Rap1B, are known for their role in cadherin-mediated adhesion, EC deletion of Rap1A after birth uniquely disrupts lung endothelial barrier function. Here, we elucidate the specific mechanisms by which Rap1A modulates lung vascular integrity and inflammation.

METHODS

The role of EC Rap1A in lung inflammation and permeability was examined using in vitro and in vivo approaches.

RESULTS

We explored Ca2+ signaling in human ECs following siRNA-mediated knockdown of Rap1A or Rap1B. Rap1A knockdown, unlike Rap1B, significantly increased store-operated calcium entry in response to a GPCR (G-protein-coupled receptor) agonist, ATP (500 µmol/L), or thapsigargin (250 nmol/L). This enhancement was attenuated by Orai1 channel blockers 10 μmol/L BTP2 (N-[4-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl]phenyl]-4-methyl-1,2,3-thiadiazole-5-carboxamide), 10 μmol/L GSK-7975A, and 5 μmol/L Gd3+. Whole-cell patch clamp measurements revealed enhanced Ca2+ release-activated Ca2+ current density in siRap1A ECs. Rap1A depletion in ECs led to increased NFAT1 nuclear translocation and activity and elevated levels of proinflammatory cytokines (CXCL1 [C-X-C motif chemokine ligand 1], CXCL11 [C-X-C motif chemokine 11], CCL5 [chemokine (C-C motif) ligand 5], and IL-6 [interleukin-6]). Notably, reducing Orai1 expression in siRap1A ECs normalized store-operated calcium entry, NFAT activity, and endothelial hyperpermeability in vitro. EC-specific Rap1A knockout (Rap1AiΔEC) mice displayed an inflammatory lung phenotype with increased lung permeability and inflammation markers, along with higher Orai1 expression. Delivery of siRNA against Orai1 to lung endothelium using lipid nanoparticles effectively normalized Orai1 levels in lung ECs, consequently reducing hyperpermeability and inflammation in Rap1AiΔEC mice.

CONCLUSIONS

Our findings uncover a novel role of Rap1A in regulating Orai1-mediated Ca2+ entry and expression, crucial for NFAT-mediated transcription and endothelial inflammation. This study distinguishes the unique function of Rap1A from that of the predominant Rap1B isoform and highlights the importance of normalizing Orai1 expression in maintaining lung vascular integrity and modulating endothelial functions.

Blockade of store-operated calcium entry by BTP2 preserves anti-inflammatory gene expression in human peripheral blood mononuclear cells

Store-operated calcium entry (SOCE) is essential for cellular signaling. Earlier studies of the pyrazole derivative BTP2, an efficient inhibitor SOCE, identified that SOCE blockade suppresses proinflammatory gene expression. The impact of SOCE blockade on gene expression at the whole transcriptome level, however, is unknown. To fill this gap, we performed RNA sequencing (RNA-seq) and investigated at the whole transcriptome level the effect of BTP2 on gene expression in human peripheral blood mononuclear cells signaled with phytohemagglutinin. Our global gene expression analysis identified that SOCE blockade spares activation-induced expression of anti-inflammatory genes (e.g., IL10, TGFB1, FOXP3, and CTLA4) whereas the induced expression of proinflammatory genes such as IFNG and cytopathic genes such as GZMB are inhibited. We validated the differential expression of immunoregulatory genes identified by RNA-seq using preamplification-enhanced RT-qPCR assays. Because IL-2/IL2RA interaction is essential for T cell clonal expansion, we investigated and confirmed that BTP2 inhibits IL2RA expression at the protein level using multiparameter flow cytometry. Our elucidation that SOCE blockade spares activation-induced expression of anti-inflammatory genes while blocking pro-inflammatory gene expression suggests that SOCE blockers may represent a novel class of immunoregulatory drugs of value for treating autoimmune disease states and organ transplantation.

Adaptive immunity of materials: Implications for tissue healing and regeneration

Recent cumulative findings signify the adaptive immunity of materials as a key agenda in tissue healing that can improve regenerative events and outcomes. Modulating immune responses, mainly the recruitment and functions of T and B cells and their further interplay with innate immune cells (e.g., dendritic cells, macrophages) can be orchestrated by materials. For instance, decellularized matrices have been shown to promote muscle healing by inducing T helper 2 (Th2) cell immunity, while synthetic biopolymers exhibit differential effects on B cell responses and fibrosis compared decellularized matrices. We discuss the recent findings on how implantable materials instruct the adaptive immune events and the subsequent tissue healing process. In particular, we dissect the materials' physicochemical properties (shape, size, topology, degradation, rigidity, and matrix dynamic mechanics) to demonstrate the relations of these parameters with the adaptive immune responses in vitro and the underlying biological mechanisms. Furthermore, we present evidence of recent in vivo phenomena, including tissue healing, cancer progression, and fibrosis, wherein biomaterials potentially shape adaptive immune cell functions and in vivo outcomes. Our discussion will help understand the materials-regulated immunology events more deeply, and offer the design rationale of materials with tunable matrix properties for accelerated tissue repair and regeneration.

Circ-CAMTA1 regulated by Ca2+ influx inhibited pyruvate carboxylase activity and modulate T cell function in patients with systemic lupus erythematosus

OBJECTIVES

To investigate the roles of Ca2+ influx-regulated circular RNAs (circRNAs) in T cells from patients with systemic lupus erythematosus (SLE).

METHODS

The expression profile of circRNAs in Jurkat cells, co-cultured with and without ionomycin, was analyzed by next-generation sequencing and validated using real-time polymerase chain reaction. The identified Ca2+ influx-regulated circRNAs were further examined in T cells from 42 patients with SLE and 23 healthy controls. The biological function of specific circRNA was investigated using transfection and RNA pull-down assay.

RESULTS

After validation, we confirmed that the expression levels of circ-ERCC4, circ-NFATC2, circ-MYH10, circ-CAMTA1, circ-ASH1L, circ-SOCS7, and circ-ASAP1 were consistently increased in Jurkat cells following Ca2+ influx. The expression levels of circ-CAMTA1, circ-ASH1L, and circ-ASAP1 were significantly lower in T cells from patients with SLE, with even lower levels observed in those with higher disease activity. Interferon (IFN)-α was found to suppress the expression of circ-CAMTA1. Circ-CAMTA1 bound to pyruvate carboxylase and inhibited its biological activity. Overexpression of circ-CAMTA1, but not its linear form, significantly decreased extracellular glucose levels. Furthermore, increased expression of circ-CAMTA1, but not its linear form, decreased miR-181c-5p expression, resulting increased IL-2 secretion.

CONCLUSION

Three Ca2+ influx-regulated circ-RNAs-circ-CAMTA1, circ-ASH1L, and circ-ASAP1 -were significantly reduced in T cells from patients with SLE and associated with disease activity. IFN-α suppressed the expression of circ-CAMTA1, which interacted with pyruvate carboxylase, inhibited its activity, affected glucose metabolism, and increased IL-2 secretion. These findings suggest that circ-CAMTA1 regulated by Ca²⁺ influx modulated T cell function in patients with SLE.

Synergistic immunotherapy with a calcium-based nanoinducer: evoking pyroptosis and remodeling tumor-associated macrophages for enhanced antitumor immune response

The challenges posed by low immunogenicity and the immunosuppressive tumor microenvironment (TME) significantly hinder the efficacy of cancer immunotherapy. Pyroptosis, characterized as a pro-inflammatory cell death pathway, emerges as a promising approach to augment immunotherapy by promoting immunogenic cell death (ICD). The predominance of M2 phenotype tumor-associated macrophages (TAMs) in the TME underscores the critical need for TAM reprogramming to mitigate this immunosuppression. Herein, we introduce a calcium-based, intelligent-responsive nanoinducer (CaZCH NPs), designed to concurrently initiate pyroptosis and remodel TAMs, thereby amplifying antitumor immunotherapy effects. Modified with hyaluronic acid, CaZCH NPs can target tumor cells. Once internalized, CaZCH NPs respond to the acidic environment, releasing Ca2+, curcumin and H2O2 to induce mitochondrial Ca2+ overload and oxidation stress, leading to caspase-3/GSDME-mediated cell pyroptosis. Concurrently, O2 produced by CaZCH and pro-inflammatory cytokines from pyroptotic cells work together to shift TAM polarization towards the M1 phenotype, effectively countering TME's immunosuppressive effect. Notably, the synergistic effect of Ca2+-mediated pyroptosis and TAM remodeling demonstrates superior antitumor efficiency in colorectal cancer models. The induced ICD, coupled with M1-type TAMs, effectively enhances immunogenicity and mitigates immunosuppression, promoting dendritic cell maturation and activating CD8+ T cell-dependent systemic antitumor immunity. Our study presents a promising synergistic strategy for achieving highly efficient immunotherapy using a simple calcium-based nanoinducer.

Adjusting to self in the thymus: CD4 versus CD8 lineage commitment and regulatory T cell development

During thymic development, thymocytes adjust their TCR response based on the strength of their reactivity to self-peptide MHC complexes. This tuning process allows thymocytes with a range of self-reactivities to survive positive selection and contribute to a diverse T cell pool. In this review, we will discuss recent advances in our understanding of how thymocytes tune their responsiveness during positive selection, and we present a "sequential selection" model to explain how MHC specificity influences lineage choice. We also discuss recent evidence for cell type diversity in the medulla and discuss how this heterogeneity may contribute to medullary niches for negative selection and regulatory T cell development.

Maintenance of X chromosome inactivation after T cell activation requires NF-κB signaling

X chromosome inactivation (XCI) balances X-linked gene dosage between sexes. Unstimulated T cells lack cytological enrichment of X-inactive specific transcript (Xist) RNA and heterochromatic modifications on the inactive X chromosome (Xi), which are involved in maintenance of XCI, and these modifications return to the Xi after stimulation. Here, we examined allele-specific gene expression and epigenomic profiles of the Xi in T cells. We found that the Xi in unstimulated T cells is largely dosage compensated and enriched with the repressive H3K27me3 modification but not the H2AK119-ubiquitin (Ub) mark. Upon T cell stimulation mediated by both CD3 and CD28, the Xi accumulated H2AK119-Ub at gene regions of previous H3K27me3 enrichment. T cell receptor (TCR) engagement, specifically NF-κB signaling downstream of the TCR, was required for Xist RNA localization to the Xi. Disruption of NF-κB signaling in mouse and human T cells using genetic deletion, chemical inhibitors, and patients with immunodeficiencies prevented Xist/XIST RNA accumulation at the Xi and altered X-linked gene expression. Our findings reveal a previously undescribed connection between NF-κB signaling pathways, which affects XCI maintenance in T cells in females.

Lack of ATP2B1 in CD4+ T Cells Causes Colitis

BACKGROUND

The ATP2B1 gene encodes for a calcium pump, which plays a role in removing Ca2+ from cells and maintaining intracellular Ca2+ homeostasis. Reduction of the intracellular Ca2+ concentration in CD4+ T cells is thought to reduce the severity of colitis, while elevation of Ca2+ in CD4+ T cells induces T cell hyperactivity. Our aim was to clarify the role of ATP2B1 in CD4+ T cells and in inflammatory bowel disease development.

METHODS

A murine CD4+ T cell-specific knockout (KO) of ATP2B1 was created using a Cre-loxP system. CD4+ T cells were isolated from thymus, spleen, and blood using fluorescence-activated cell sorting. To quantify messenger RNA levels, quantitative real-time polymerase chain reaction was performed.

RESULTS

Although the percentages of CD4+ T cells in both KO mouse spleen and blood decreased compared with those of the control samples, both T-bet (a T helper 1 [Th1] activity marker) and GATA3 (a Th2 activity marker) expression levels were further increased in KO mouse blood CD4+ T cells (vs control blood). Diarrhea and colonic wall thickening (with mucosal changes, including crypt distortion) were seen in KO mice but not in control mice. Prior to diarrhea onset, the KO mouse colon length was already noted to be shorter, and the KO mouse stool water and lipid content were higher than that of the control mice. Tumor necrosis factor α and gp91 expressions were increased in KO mouse colon.

CONCLUSIONS

Lack of ATP2B1 in CD4+ T cells leads to Th1 and Th2 activation, which contributes to colitis via elevation of tumor necrosis factor α and oxidative stress.

Life history of a brain autoreactive T cell: From thymus through intestine to blood-brain barrier and brain lesion

Brain antigen-specific autoreactive T cells seem to play a key role in inducing inflammation in the central nervous system (CNS), a characteristic feature of human multiple sclerosis (MS). These T cells are generated within the thymus, where they escape negative selection and become integrated into the peripheral immune repertoire of immune cells. Typically, these autoreactive T cells rest in the periphery without attacking the CNS. When autoimmune T cells enter gut-associated lymphatic tissue (GALT), they may be stimulated by the microbiota and its metabolites. After activation, the cells migrate into the CNS through the blood‒brain barrier, become reactivated upon interacting with local antigen-presenting cells, and induce inflammatory lesions within the brain parenchyma. This review describes how microbiota influence autoreactive T cells during their life, starting in the thymus, migrating through the periphery and inducing inflammation in their target organ, the CNS.

STING-STAT6 Signaling Pathway Promotes IL-4+ and IFN-α+ Fibrotic T Cell Activation and Exacerbates Scleroderma in SKG Mice

Systemic sclerosis (SS) is an autoimmune disease and pathological mechanisms of SS are unclear. In this study, we investigated the role of T cells in the progression of SS using SKG mice and humanized mice. SKG mice have a spontaneous point mutation in ZAP70. We induced scleroderma in SKG mice and a humanized SS mouse model to assess whether T cell-mediated immune responses induce SS. As a result, we found increased dermal thickness, fibrosis, and lymphocyte infiltration in skin tissue in SKG SS mice compared to BALB/c mice (control). Also, blood cytokine level, including IL-4- and IFN-α which are produced by CD4+ T cells via STIM1/STING/STAT6/IRF3 signaling pathways, were increased in SKG mice. Interestingly, skin fibrosis was reduced by inhibiting STING pathway in skin fibroblast. Next, we demonstrated the pathophysiological role of IL-4 and IFN-α in skin fibrosis using a humanized SS mouse model and found increased IL-4- and IFN-α-producing CD4+ T cells and fibrosis. In this study, we found that STING-induced production of IL-4- and type I IFN by CD4+ T cells is a key factor in mouse model and humanized mouse model of SS. Our findings suggest that the STING/STAT6/IRF3 signaling pathways are potential therapeutic targets in SS.

Calcium dynamics of skin-resident macrophages during homeostasis and tissue injury

Immune cells depend on rapid changes in intracellular calcium activity to modulate cell function. Skin contains diverse immune cell types and is critically dependent on calcium signaling for homeostasis and repair, yet the dynamics and functions of calcium in skin immune cells remain poorly understood. Here, we characterize calcium activity in Langerhans cells, skin-resident macrophages responsible for surveillance and clearance of cellular debris after tissue damage. Langerhans cells reside in the epidermis and extend dynamic dendrites in close proximity to adjacent keratinocytes and somatosensory peripheral axons. We find that homeostatic Langerhans cells exhibit spontaneous and transient changes in calcium activity, with calcium flux occurring primarily in the cell body and rarely in the dendrites. Triggering somatosensory axon degeneration increases the frequency of calcium activity in Langerhans cell dendrites. By contrast, we show that Langerhans cells exhibit a sustained increase in intracellular calcium following engulfment of damaged keratinocytes. Altering intracellular calcium activity leads to a decrease in engulfment efficiency of keratinocyte debris. Our findings demonstrate that Langerhans cells exhibit context-specific changes in calcium activity and highlight the utility of skin as an accessible model for imaging calcium dynamics in tissue-resident macrophages.

Physiologically Achievable Concentration of 2-Deoxy-D-Glucose Stimulates IFN-γ Secretion in Activated T Cells In Vitro

2-deoxy-D-glucose (2DG) is a glycolysis and protein N-glycosylation inhibitor with promising anti-tumor and immunomodulatory effects. However, 2DG can also suppress T cell function, including IFN-γ secretion. Few human T cell studies have studied low-dose 2DG, which can increase IFN-γ in a Jurkat clone. We therefore investigated 2DG's effect on IFN-γ in activated human T cells from PBMCs, with 2DG treatment commenced either concurrently with activation or 48 h after activation. Concurrent 2DG treatment decreased IFN-γ secretion in a dose-dependent manner. However, 2DG treatment of pre-activated T cells had a hormetic effect on IFN-γ, with 0.15-0.6 mM 2DG (achievable in vivo) increasing and >2.4 mM 2DG reducing its secretion. In contrast, IL-2 levels declined monotonously with increasing 2DG concentration. Lower 2DG concentrations reduced PD-1 and increased CD69 expression regardless of treatment timing. The absence of increased T-bet or Eomes expression or IFNG transcription suggests another downstream mechanism. 2DG dose-dependently induced the unfolded protein response, suggesting a possible role in increased IFN-γ secretion, possibly by increasing the ER folding capacity for IFN-γ via increased chaperone expression. Overall, low-dose, short-term 2DG exposure could potentially improve the T cell anti-tumor response.

Metabolic mediators: microbial-derived metabolites as key regulators of anti-tumor immunity, immunotherapy, and chemotherapy

The human microbiome has recently emerged as a focal point in cancer research, specifically in anti-tumor immunity, immunotherapy, and chemotherapy. This review explores microbial-derived metabolites, emphasizing their crucial roles in shaping fundamental aspects of cancer treatment. Metabolites such as short-chain fatty acids (SCFAs), Trimethylamine N-Oxide (TMAO), and Tryptophan Metabolites take the spotlight, underscoring their diverse origins and functions and their profound impact on the host immune system. The focus is on SCFAs' remarkable ability to modulate immune responses, reduce inflammation, and enhance anti-tumor immunity within the intricate tumor microenvironment (TME). The review critically evaluates TMAO, intricately tied to dietary choices and gut microbiota composition, assessing its implications for cancer susceptibility, progression, and immunosuppression. Additionally, the involvement of tryptophan and other amino acid metabolites in shaping immune responses is discussed, highlighting their influence on immune checkpoints, immunosuppression, and immunotherapy effectiveness. The examination extends to their dynamic interaction with chemotherapy, emphasizing the potential of microbial-derived metabolites to alter treatment protocols and optimize outcomes for cancer patients. A comprehensive understanding of their role in cancer therapy is attained by exploring their impacts on drug metabolism, therapeutic responses, and resistance development. In conclusion, this review underscores the pivotal contributions of microbial-derived metabolites in regulating anti-tumor immunity, immunotherapy responses, and chemotherapy outcomes. By illuminating the intricate interactions between these metabolites and cancer therapy, the article enhances our understanding of cancer biology, paving the way for the development of more effective treatment options in the ongoing battle against cancer.

A pleiotropic recurrent dominant ITPR3 variant causes a complex multisystemic disease

Inositol 1,4,5-trisphosphate (IP3) receptor type 1 (ITPR1), 2 (ITPR2), and 3 (ITPR3) encode the IP3 receptor (IP3R), a key player in intracellular calcium release. In four unrelated patients, we report that an identical ITPR3 de novo variant-NM_002224.3:c.7570C>T, p.Arg2524Cys-causes, through a dominant-negative effect, a complex multisystemic disorder with immunodeficiency. This leads to defective calcium homeostasis, mitochondrial malfunction, CD4+ lymphopenia, a quasi-absence of naïve CD4+ and CD8+ cells, an increase in memory cells, and a distinct TCR repertoire. The calcium defect was recapitulated in Jurkat knock-in. Site-directed mutagenesis displayed the exquisite sensitivity of Arg2524 to any amino acid change. Despite the fact that all patients had severe immunodeficiency, they also displayed variable multisystemic involvements, including ectodermal dysplasia, Charcot-Marie-Tooth disease, short stature, and bone marrow failure. In conclusion, unlike previously reported ITPR1-3 deficiencies leading to narrow, mainly neurological phenotypes, a recurrent dominant ITPR3 variant leads to a multisystemic disease, defining a unique role for IP3R3 in the tetrameric IP3R complex.

Hypoalbuminemia and hypercalcemia are independently associated with poor treatment outcomes of anti-PD-1 immune checkpoint inhibitors in patients with recurrent or metastatic head and neck squamous cell carcinoma

BACKGROUND

Recent randomized phase III trials have demonstrated the efficacy of anti-programmed cell death 1 (PD-1) immune checkpoint inhibitors (ICIs) in treating patients with recurrent or metastatic head and neck squamous cell carcinoma (RMHNSCC). However, a large proportion of such patients still have poor response. This study aimed to identify biomarkers for predicting anti-PD-1 ICI treatment outcomes .

METHODS

We retrospectively analyzed 144 patients with RMHNSCC who received anti-PD-1 ICIs after progression to platinum-based chemotherapy between January 2017 and December 2022 at Kaohsiung Chang Gung Memorial Hospital. Data on clinicopathological parameters, albumin levels, calcium levels, and other pretreatment peripheral blood biomarkers, including total lymphocyte count, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and prognostic nutritional index (PNI) were collected and correlated with the treatment outcome of anti-PD-1 ICIs.

RESULTS

Low tumor proportion score (TPS), low combined positive score (CPS), NLR ≥ 5, PLR ≥ 300, hypercalcemia, hypoalbuminemia, and PNI < 45 were significantly correlated with poor response of ICIs. The overall response rates were 25% and 3% in patients with calcium < 10 mg/dL and calcium ≥ 10 mg/dL, respectively (P = 0.007). The overall response rates were 6% and 33% in patients with albumin < 4 g/dL and albumin ≥ 4 g/dL, respectively (P < 0.001). Univariate survival analysis showed that low TPS, low CPS, NLR ≥ 5,, hypercalcemia, hypoalbuminemia, and PNI < 45 were significantly associated with worse progression-free survival (PFS) and inferior overall survival (OS). Multivariate analysis revealed that calcium ≥ 10 mg/dL and albumin < 4 g/dL were independent poor prognosticators for worse PFS and inferior OS. The two-year OS rates were 26% and 9% in patients with calcium < 10 mg/dL and ≥ 10 mg/dL, respectively (P < 0.001). The two-year OS rates were 10% and 33% in patients with albumin < 4 g/dL and ≥ 4 g/dL, respectively (P < 0.001).

CONCLUSIONS

Hypercalcemia and hypoalbuminemia can potentially predict poor treatment outcomes of anti-PD-1 ICIs in patients with RMHNSCC. Blood calcium and albumin levels may be helpful in individualizing treatment strategies for patients with RMHNSCC.

Regulation of Cell Membrane Potential through Supramolecular System for Activating Calcium Ion Channels

The regulation of the cell membrane potential plays a crucial role in governing the transmembrane transport of various ions and cellular life processes. However, in situ and on-demand modulation of cell membrane potential for ion channel regulation is challenging. Herein, we have constructed a supramolecular assembly system based on water-soluble cationic oligo(phenylenevinylene) (OPV) and cucurbit[7]uril (CB[7]). The controllable disassembly of OPV/4CB[7] combined with the subsequent click reaction provides a step-by-step adjustable surface positive potential. These processes can be employed in situ on the plasma membrane to modulate the membrane potential on-demand for precisely controlling the activation of the transient receptor potential vanilloid 1 (TRPV1) ion channel and up-regulating exogenous calcium-responsive gene expression. Compared with typical optogenetics, electrogenetics, and mechanogenetics, our strategy provides a perspective supramolecular genetics toolbox for the regulation of membrane potential and downstream intracellular gene regulation events.

Human organoids with an autologous tissue-resident immune compartment

The intimate relationship between the epithelium and immune system is crucial for maintaining tissue homeostasis, with perturbations therein linked to autoimmune disease and cancer1-3. Whereas stem cell-derived organoids are powerful models of epithelial function4, they lack tissue-resident immune cells that are essential for capturing organ-level processes. We describe human intestinal immuno-organoids (IIOs), formed through self-organization of epithelial organoids and autologous tissue-resident memory T (TRM) cells, a portion of which integrate within the epithelium and continuously survey the barrier. TRM cell migration and interaction with epithelial cells was orchestrated by TRM cell-enriched transcriptomic programs governing cell motility and adhesion. We combined IIOs and single-cell transcriptomics to investigate intestinal inflammation triggered by cancer-targeting biologics in patients. Inflammation was associated with the emergence of an activated population of CD8+ T cells that progressively acquired intraepithelial and cytotoxic features. The appearance of this effector population was preceded and potentiated by a T helper-1-like CD4+ population, which initially produced cytokines and subsequently became cytotoxic itself. As a system amenable to direct perturbation, IIOs allowed us to identify the Rho pathway as a new target for mitigation of immunotherapy-associated intestinal inflammation. Given that they recapitulate both the phenotypic outcomes and underlying interlineage immune interactions, IIOs can be used to study tissue-resident immune responses in the context of tumorigenesis and infectious and autoimmune diseases.

Multifunctional Biomimetic Nanocarriers for Dual-Targeted Immuno-Gene Therapy Against Hepatocellular Carcinoma

Growing evidences have proved that tumors evade recognition and attack by the immune system through immune escape mechanisms, and PDL1/Pbrm1 genes have a strong correlation with poor response or resistance to immune checkpoint blockade (ICB) therapy. Herein, a multifunctional biomimetic nanocarrier (siRNA-CaP@PD1-NVs) is developed, which can not only enhance the cytotoxic activity of immune cells by blocking PD1/PDL1 axis, but also reduce tumor immune escape via Pbrm1/PDL1 gene silencing, leading to a significant improvement in tumor immunosuppressive microenvironment. Consequently, the nanocarrier promotes DC cell maturation, enhances the infiltration and activity of CD8+ T cells, and forms long-term immune memory, which can effectively inhibit tumor growth or even eliminate tumors, and prevent tumor recurrence and metastasis. Overall, this study presents a powerful strategy for co-delivery of siRNA drugs, immune adjuvant, and immune checkpoint inhibitors, and holds great promise for improving the effectiveness and safety of current immunotherapy regimens.

An acid-activatable fluorouracil prodrug for colorectal cancer synergistic therapy

5-Fluorouracil has demonstrated certain efficiency in patients with colorectal cancer. However, significant side effects of use by injection are common. To address this issue defects, a reengineered 5'-deoxy-5-fluorocytidine (DFCR) based drug delivery system (POACa) is developed as a prominent tumor-selective nano-activator. Investigations demonstrate that the constructed nano-activator exhibits good biocompatibility and high therapeutic efficiency in mice with subcutaneous and orthotopic SW-480 colorectal tumors, as its activity is strictly dependent on the tumor-associated acid environment and thymidine phosphorylase. These strategies diminish the off-target toxicity and improve the specificity and sensitivity of human colorectal cancer cells to 5-Fu, obtaining potent efficiency by the combination of H2O2 mediated oxidative stress, calcium overload and 5-Fu-induced chemotherapy (the combination index is 0.11). Overall, the engineered nano-activator exhibits a high therapeutic index in vitro and in vivo. STATEMENT OF SIGNIFICANCE: In this study, we designed and prepared a pH-responsive polymer to synchronously deliver DFCR (5'-deoxy-5-fluorocytidine, a prodrug of 5-Fu), Ca2+ and H2O2. The constructed nano-activator was denoted as POACa. (1) To address the problem of premature leakage of cargo by physical embedding, our research modified the inactive prodrug DFCR through chemical bonding. (2) The activation of the prepared nano-activator was strictly dependent on the tumor-associated acid environment and thymidine phosphorylase, providing the drug delivery system with inherent safety. (3) A distinctly low combination index value (0.11) of CaO2 and DFCR indicated that POACa has a prominent tumor suppression effect by tumor calcium overload sensitized chemotherapy and H2O2 mediated cytotoxicity.