Transient hydroxycholesterol treatment restrains TCR signaling to promote long-term immunity.

T cell receptor (TCR) plays a fundamental role in adaptive immunity, and TCR-T cell therapy holds great promise for treating solid tumors and other diseases. However, there is a noticeable absence of chemical tools tuning TCR activity. In our study, we screened natural sterols for their regulatory effects on T cell function and identified 7-alpha-hydroxycholesterol (7a-HC) as a potent inhibitor of TCR signaling. Mechanistically, 7a-HC promoted membrane binding of CD3ε cytoplasmic domain, a crucial signaling component of the TCR-CD3 complex, through alterations in membrane physicochemical properties. Enhanced CD3ε membrane binding impeded the condensation between CD3ε and the key kinase Lck, thereby inhibiting Lck-mediated TCR phosphorylation. Transient treatments of TCR-T cells with 7a-HC resulted in reduced signaling strength, increased memory cell populations, and superior long-term antitumor functions. This study unveils a chemical regulation of TCR signaling, which can be exploited to enhance the long-term efficacy of TCR-T cell therapy.

The relationship between thiamin, folic acid and cognitive function in a rat model of uremia.

End-stage renal disease is a worldwide health burden, but the pathogenesis of uremia-associated cognitive impairment (CI) is poorly recognized. We hypothesized that uremia brings about deficiency of thiamin and folic acid and causes CI by inducing oxidative stress. Therefore, 24 Sprague-Dawley rats were randomly divided into two groups: a 5/6 nephrectomy group (n = 12) and a sham-operated group (n = 12). The Morris water maze was used to assess the cognitive function eight weeks post-surgery, and serum levels of thiamin, folic acid and homocysteine were detected subsequently. Brain and kidney tissues were collected for pathological examination and 8-Hydroxy-2'-deoxyguanosine (8-OHdG) immunochemistry staining. Results showed that the escape latency on training days 1-2 was longer, and the time in quadrant IV on experimental day 6 was significantly shorter in 5/6 nephrectomy group. Meanwhile, the uremic rats showed decreased thiamin, folic acid and increased homocysteine. We also found the time in quadrant IV was positively correlated with thiamin and folic acid level, while negatively correlated with the blood urea nitrogen and 8-OHdG positive cell proportion. Furthermore, in 5/6 nephrectomy group, the hippocampal neuron count was significantly reduced, and a greater proportion of 8-OHdG positive cells were detected. Pretreating LPS-stimulated rat microglial cells with thiamin or folic acid in vitro alleviated the inflammatory impairment in terms of cell viability and oxidative stress. In summary, we applied a uremic rat model and proved that uremia causes serum thiamin and folic acid deficiency, homocysteine elevation, along with neuron reduction and severe oxidative stress in hippocampus, finally leading to CI.

Platinum-group-metal quaternary alloys with lattice defects for enhanced oxygen electrocatalysis.

We propose a facile coreduction method to synthesize a platinum-group-metal quaternary alloy anchored on nitrogen-doped hollow carbon spheres (PtPdRuIr/HCS) by using [MClx]y--1-butyl-3-methylimidazole (M = Pt, Pd, Ru, and Ir) ionic liquid. Owing to the steric hindrance of the imidazolium cations, Pt-group metal atoms of different sizes can be deposited at approximately the same pace for the growth of an alloy with lattice defects. The lattice-distorted PtPdRuIr/HCS exhibits enhanced activity toward oxygen electroreduction when benchmarked against Pt counterparts.

Shaping immune landscape of colorectal cancer by cholesterol metabolites.

Cancer immunotherapies have achieved unprecedented success in clinic, but they remain largely ineffective in some major types of cancer, such as colorectal cancer with microsatellite stability (MSS CRC). It is therefore important to study tumor microenvironment of resistant cancers for developing new intervention strategies. In this study, we identify a metabolic cue that determines the unique immune landscape of MSS CRC. Through secretion of distal cholesterol precursors, which directly activate RORγt, MSS CRC cells can polarize T cells toward Th17 cells that have well-characterized pro-tumor functions in colorectal cancer. Analysis of large human cancer cohorts revealed an asynchronous pattern of the cholesterol biosynthesis in MSS CRC, which is responsible for the abnormal accumulation of distal cholesterol precursors. Inhibiting the cholesterol biosynthesis enzyme Cyp51, by pharmacological or genetic interventions, reduced the levels of intratumoral distal cholesterol precursors and suppressed tumor progression through a Th17-modulation mechanism in preclinical MSS CRC models. Our study therefore reveals a novel mechanism of cancer-immune interaction and an intervention strategy for the difficult-to-treat MSS CRC.

Self-programmed dynamics of T cell receptor condensation.

A common event upon receptor-ligand engagement is the formation of receptor clusters on the cell surface, in which signaling molecules are specifically recruited or excluded to form signaling hubs to regulate cellular events. These clusters are often transient and can be disassembled to terminate signaling. Despite the general relevance of dynamic receptor clustering in cell signaling, the regulatory mechanism underlying the dynamics is still poorly understood. As a major antigen receptor in the immune system, T cell receptors (TCR) form spatiotemporally dynamic clusters to mediate robust yet temporal signaling to induce adaptive immune responses. Here we identify a phase separation mechanism controlling dynamic TCR clustering and signaling. The TCR signaling component CD3ε chain can condensate with Lck kinase through phase separation to form TCR signalosomes for active antigen signaling. Lck-mediated CD3ε phosphorylation, however, switched its binding preference to Csk, a functional suppressor of Lck, to cause the dissolvement of TCR signalosomes. Modulating TCR/Lck condensation by targeting CD3ε interactions with Lck or Csk directly affects T cell activation and function, highlighting the importance of the phase separation mechanism. The self-programmed condensation and dissolvement is thus a built-in mechanism of TCR signaling and might be relevant to other receptors.

IGFBP1 Sustains Cell Survival during Spatially-Confined Migration and Promotes Tumor Metastasis.

Cell migration is a pivotal step in metastatic process, which requires cancer cells to navigate a complex spatially-confined environment, including tracks within blood vessels and in the vasculature of target organs. Here it is shown that during spatially-confined migration, the expression of insulin-like growth factor-binding protein 1 (IGFBP1) is upregulated in tumor cells. Secreted IGFBP1 inhibits AKT1-mediated phosphorylation of mitochondrial superoxide dismutase (SOD2) serine (S) 27 and enhances SOD2 activity. Enhanced SOD2 attenuates mitochondrial reactive oxygen species (ROS) accumulation in confined cells, which supports tumor cell survival in blood vessels of lung tissues, thereby accelerating tumor metastasis in mice. The levels of blood IGFBP1 correlate with metastatic recurrence of lung cancer patients. This finding reveals a unique mechanism by which IGFBP1 sustains cell survival during confined migration by enhancing mitochondrial ROS detoxification, thereby promoting tumor metastasis.

Charging CAR by electrostatic power.

Chimeric antigen receptor (CAR)-T cell therapy has emerged as a promising approach for cancer treatment. CAR is a synthetic immune receptor that recognizes tumor antigen and activates T cells through multiple signaling pathways. However, the current CAR design is not as robust as T cell receptor (TCR), a natural antigen receptor with high sensitivity and efficiency. TCR signaling relies on specific molecular interactions, and thus electrostatic force, the major force of molecular interactions, play critical roles. Understanding how electrostatic charge regulates TCR/CAR signaling events will facilitate the development of next-generation T cell therapies. This review summarizes recent findings on the roles of electrostatic interactions in both natural and synthetic immune receptor signaling, specifically that in CAR clustering and effector molecule recruitments, and highlights potential strategies for engineering CAR-T cell therapy by leveraging charge-based interactions.

Soluble interleukin-2 receptor combined with interleukin-8 is a powerful predictor of future adverse cardiovascular events in patients with acute myocardial infarction.

Background: Little is known about the role of interleukin (IL) in patients with acute myocardial infarction (MI), especially soluble IL-2 receptor (sIL-2R) and IL-8. We aim to evaluate, in MI patients, the predictive value of serum sIL-2R and IL-8 for future major adverse cardiovascular events (MACEs), and compare them with current biomarkers reflecting myocardial inflammation and injury. Methods: This was a prospective, single-center cohort study. We measured serum concentrations of IL-1ß, sIL-2R, IL-6, IL-8 and IL-10. Levels of current biomarkers for predicting MACEs were measured, including high-sensitivity C reactive protein, cardiac troponin T and N-terminal pro-brain natriuretic peptide. Clinical events were collected during 1-year and a median of 2.2 years (long-term) follow-up. Results: Twenty-four patients (13.8%, 24/173) experienced MACEs during 1-year follow-up and 40 patients (23.1%, 40/173) during long-term follow-up. Of the five interleukins studied, only sIL-2R and IL-8 were independently associated with endpoints during 1-year or long-term follow-up. Patients with high sIL-2R or IL-8 levels (higher than the cutoff value) had a significantly higher risk of MACEs during 1-year (sIL-2R: HR 7.7, 3.3-18.0, p < 0.001; IL-8: HR 4.8, 2.1-10.7, p < 0.001) and long-term (sIL-2R: HR 7.7, 3.3-18.0, p < 0.001; IL-8: HR 4.8, 2.1-10.7, p < 0.001) follow-up. Receiver operator characteristic curve analysis regarding predictive accuracy for MACEs during 1-year follow-up showed that the area under the curve for sIL-2R, IL-8, sIL-2R combined with IL-8 was 0.66 (0.54-0.79, p = 0.011), 0.69 (0.56-0.82, p < 0.001) and 0.720 (0.59-0.85, p < 0.001), whose predictive value were superior to that of current biomarkers. The addition of sIL-2R combined with IL-8 to the existing prediction model resulted in a significant improvement in predictive power (p = 0.029), prompting a 20.8% increase in the proportion of correct classifications. Conclusions: High serum sIL-2R combined with IL-8 levels was significantly associated with MACEs during follow-up in patients with MI, suggesting that sIL-2R combined with IL-8 may be a helpful biomarker for identifying the increased risk of new cardiovascular events. IL-2 and IL-8 would be promising therapeutic targets for anti-inflammatory therapy.

Exhaustion-associated cholesterol deficiency dampens the cytotoxic arm of antitumor immunity.

The concept of targeting cholesterol metabolism to treat cancer has been widely tested in clinics, but the benefits are modest, calling for a complete understanding of cholesterol metabolism in intratumoral cells. We analyze the cholesterol atlas in the tumor microenvironment and find that intratumoral T cells have cholesterol deficiency, while immunosuppressive myeloid cells and tumor cells display cholesterol abundance. Low cholesterol levels inhibit T cell proliferation and cause autophagy-mediated apoptosis, particularly for cytotoxic T cells. In the tumor microenvironment, oxysterols mediate reciprocal alterations in the LXR and SREBP2 pathways to cause cholesterol deficiency of T cells, subsequently leading to aberrant metabolic and signaling pathways that drive T cell exhaustion/dysfunction. LXRß depletion in chimeric antigen receptor T (CAR-T) cells leads to improved antitumor function against solid tumors. Since T cell cholesterol metabolism and oxysterols are generally linked to other diseases, the new mechanism and cholesterol-normalization strategy might have potential applications elsewhere.

Palladium Enhanced Iron Active Site - An Efficient Dual-Atom Catalyst for Oxygen Electroreduction.

Metal-nitrogen-carbon (M-C/N) electrocatalysts have been shown to have satisfactory catalytic activity and long-term durability for the oxygen reduction reaction (ORR). Here, a strategy to prepare a new electrocatalyst (Fe&Pd-C/N) using a unique metal-containing ionic liquid (IL) is exploited, in which Fe & Pd ions are positively charged species atomically dispersed by coordination to the N of the N-doped C substrate, C/N. X-ray absorption fine structure, XPS and aberration-corrected transmission electron microscopy results verified a well-defined dual-atom configuration comprising Fe+2.x -N4 coupled Pd2+ -N4 sites and well-defined spatial distribution. Electronic control of a coupled Fe-Pd structure produces an electrocatalyst that exhibits superior performance with enhanced activity and durability for the ORR compared to that of commercial Pt/C (20%, Johnson Matthey) in both alkaline and acid media. Density functional theory calculations indicate that Pd atom can enhance the catalytic activity of the Fe active sites adjacent to Pd sites by changing the electronic orbital structure and Bader charge of the Fe centers. The excellent catalytic performance of the Fe&Pd-C/N electrocatalyst is demonstrated in zinc-air batteries and hydrogen-air fuel cells.

Tuning charge density of chimeric antigen receptor optimizes tonic signaling and CAR-T cell fitness.

Tonic signaling of chimeric antigen receptor (CAR), i.e., the spontaneous CAR activation in the absence of tumor antigen stimulation, is considered to be a pivotal event controlling CAR-T efficacy. However, the molecular mechanism underlying the spontaneous CAR signals remains elusive. Here, we unveil that positively charged patches (PCPs) on the surface of the CAR antigen-binding domain mediate CAR clustering and result in CAR tonic signaling. For CARs with high tonic signaling (e.g., GD2.CAR and CSPG4.CAR), reducing PCPs on CARs or boosting ionic strength in the culture medium during ex vivo CAR-T cell expansion minimizes spontaneous CAR activation and alleviates CAR-T cell exhaustion. In contrast, introducing PCPs into the CAR with weak tonic signaling, such as CD19.CAR, results in improved in vivo persistence and superior antitumor function. These results demonstrate that CAR tonic signaling is induced and maintained by PCP-mediated CAR clustering. Notably, the mutations we generated to alter the PCPs maintain the antigen-binding affinity and specificity of the CAR. Therefore, our findings suggest that the rational tuning of PCPs to optimize tonic signaling and in vivo fitness of CAR-T cells is a promising design strategy for the next-generation CAR.

INPP5K controls the dynamic structure and signaling of wild-type and mutated, leukemia-associated IL-7 receptors.

The downstream signaling of the interleukin-7 (IL-7) receptor (IL-7R) plays important physiological and pathological roles, including the differentiation of lymphoid cells and proliferation of acute lymphoblastic leukemia cells. Gain-of-function mutations in the IL-7Rα chain, the specific component of the receptor for IL-7, result in constitutive, IL-7-independent signaling and trigger acute lymphoblastic leukemia. Here, we show that the loss of the phosphoinositide 5-phosphatase INPP5K is associated with increased levels of the INPP5K substrate phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P2) and causes an altered dynamic structure of the IL-7 receptor. We discovered that the IL-7Rα chain contains a very conserved positively charged polybasic amino acid sequence in its cytoplasmic juxtamembrane region; this region establish stronger ionic interactions with negatively charged PtdIns(4,5)P2 in the absence of INPP5K, freezing the IL-7Rα chain structure. This dynamic structural alteration causes defects in IL-7R signaling, culminating in decreased expressions of EBF1 and PAX5 transcription factors, in microdomain formation, cytoskeletal reorganization, and bone marrow B-cell differentiation. Similar alterations after the reduced INPP5K expression also affected mutated, constitutively activated IL-7Rα chains that trigger leukemia development, leading to reduced cell proliferation. Altogether, our results indicate that the lipid 5-phosphatase INPP5K hydrolyzes PtdIns(4,5)P2, allowing the requisite conformational changes of the IL-7Rα chain for optimal signaling.

Hydroxyl-/Carboxyl-Rich Graphitic Carbon Nitride/Graphene Oxide Composites for Efficient Photodegradation of Reactive Red 195 and Antibacterial Applications.

In this work, a protonated graphitic carbon nitride (P-g-C3N4)-coated graphene oxide (GO) composite (GO/P-g-C3N4) was prepared via wet-chemistry exfoliation, followed by a freeze-drying process. The GO/P-g-C3N4 composite was found to have an outstanding photodegradation performance effect on the reactive red 195 (RR195) dye and very strong antibacterial properties. Both the GO structure and the dispersed state of P-g-C3N4 were found to play a significant role in enhancing the photocatalytic activity of GO/P-g-C3N4. The GO/P-g-C3N4 obtained via freeze-drying retained a large number of oxygen-containing groups and showed higher catalytic activity and reusability than the reduced GO (rGO)/g-C3N4 obtained via thermal reduction. Characterization of the samples indicates that GO/P-g-C3N4 has a higher specific surface area and photocurrent density than rGO/g-C3N4; it is likely that these properties lead to the superior photocatalytic activity observed in GO/P-g-C3N4. Adsorption energy calculations indicate that O2 can be readily adsorbed onto the GO surface, which results in stronger oxidizing superoxide anion radicals (•O2-) and holes (h+); these active radicals can rapidly degrade RR195 dyes. Moreover, broad-spectrum antibacterial activity (demonstrated against Staphylococcus aureus and Escherichia coli) was observed in the case of the GO/P-g-C3N4 composite irradiated with visible light. This work offers new insights into the design of cost-effective g-C3N4-based photocatalysts for environmental remediation.

Cellular basis of enhanced humoral immunity to SARS-CoV-2 upon homologous or heterologous booster vaccination analyzed by single-cell immune profiling.

SARS-CoV-2 vaccine booster dose can induce a robust humoral immune response, however, its cellular mechanisms remain elusive. Here, we investigated the durability of antibody responses and single-cell immune profiles following booster dose immunization, longitudinally over 6 months, in recipients of a homologous BBIBP-CorV/BBIBP-CorV or a heterologous BBIBP-CorV/ZF2001 regimen. The production of neutralizing antibodies was dramatically enhanced by both booster regimens, and the antibodies could last at least six months. The heterologous booster induced a faster and more robust plasmablast response, characterized by activation of plasma cells than the homologous booster. The response was attributed to recall of memory B cells and the de novo activation of B cells. Expanded B cell clones upon booster dose vaccination could persist for months, and their B cell receptors displayed accumulated mutations. The production of antibody was positively correlated with antigen presentation by conventional dendritic cells (cDCs), which provides support for B cell maturation through activation and development of follicular helper T (Tfh) cells. The proper activation of cDC/Tfh/B cells was likely fueled by active energy metabolism, and glutaminolysis might also play a general role in promoting humoral immunity. Our study unveils the cellular mechanisms of booster-induced memory/adaptive humoral immunity and suggests potential strategies to optimize vaccine efficacy and durability in future iterations.

Disulfiram bolsters T-cell anti-tumor immunity through direct activation of LCK-mediated TCR signaling.

Activation of the T-cell antigen receptor (TCR)-CD3 complex is critical to induce the anti-tumor response of CD8+ T cells. Here, we found that disulfiram (DSF), an FDA-approved drug previously used to treat alcohol dependency, directly activates TCR signaling. Mechanistically, DSF covalently binds to Cys20/Cys23 residues of lymphocyte-specific protein tyrosine kinase (LCK) and enhances its tyrosine 394 phosphorylation, thereby promoting LCK kinase activity and boosting effector T cell function, interleukin-2 production, metabolic reprogramming, and proliferation. Furthermore, our in vivo data revealed that DSF promotes anti-tumor immunity against both melanoma and colon cancer in mice by activating CD8+ T cells, and this effect was enhanced by anti-PD-1 co-treatment. We conclude that DSF directly activates LCK-mediated TCR signaling to induce strong anti-tumor immunity, providing novel molecular insights into the therapeutic effect of DSF on cancer.

Exploiting T cell signaling to optimize engineered T cell therapies.

Engineered T cell therapies, mainly chimeric antigen receptor (CAR)-T and T cell receptor (TCR)-T, have become the new frontier of cancer treatment. CAR-T and TCR-T therapies differ in many aspects, including cell persistence and toxicity, leading to different therapeutic outcomes. Both TCR and CAR recognize antigens and trigger T cell mediated antitumor response, but they have distinct molecular structures and signaling properties. TCR represents one of the most complex receptors, while CAR is a single-chain chimera integrating modules from multiple immune receptors. Understanding the mechanisms underlying the strengths and limitations of both systems can pave the way for the development of next-generation T cell therapy. This review synthesizes recent findings on TCR and CAR signaling and highlights the potential strategies of T cell engineering by signaling refinement.

Uncovering a conserved vulnerability site in SARS-CoV-2 by a human antibody.

An essential step for SARS-CoV-2 infection is the attachment to the host cell receptor by its Spike receptor-binding domain (RBD). Most of the existing RBD-targeting neutralizing antibodies block the receptor-binding motif (RBM), a mutable region with the potential to generate neutralization escape mutants. Here, we isolated and structurally characterized a non-RBM-targeting monoclonal antibody (FD20) from convalescent patients. FD20 engages the RBD at an epitope distal to the RBM with a KD of 5.6 nM, neutralizes SARS-CoV-2 including the current Variants of Concern such as B.1.1.7, B.1.351, P.1, and B.1.617.2 (Delta), displays modest cross-reactivity against SARS-CoV, and reduces viral replication in hamsters. The epitope coincides with a predicted "ideal" vulnerability site with high functional and structural constraints. Mutation of the residues of the conserved epitope variably affects FD20-binding but confers little or no resistance to neutralization. Finally, in vitro mode-of-action characterization and negative-stain electron microscopy suggest a neutralization mechanism by which FD20 destructs the Spike. Our results reveal a conserved vulnerability site in the SARS-CoV-2 Spike for the development of potential antiviral drugs.

PD-L1 degradation is regulated by electrostatic membrane association of its cytoplasmic domain.

The cytoplasmic domain of PD-L1 (PD-L1-CD) regulates PD-L1 degradation and stability through various mechanism, making it an attractive target for blocking PD-L1-related cancer signaling. Here, by using NMR and biochemical techniques we find that the membrane association of PD-L1-CD is mediated by electrostatic interactions between acidic phospholipids and basic residues in the N-terminal region. The absence of the acidic phospholipids and replacement of the basic residues with acidic residues abolish the membrane association. Moreover, the basic-to-acidic mutations also decrease the cellular abundance of PD-L1, implicating that the electrostatic interaction with the plasma membrane mediates the cellular levels of PD-L1. Interestingly, distinct from its reported function as an activator of AMPK in tumor cells, the type 2 diabetes drug metformin enhances the membrane dissociation of PD-L1-CD by disrupting the electrostatic interaction, thereby decreasing the cellular abundance of PD-L1. Collectively, our study reveals an unusual regulatory mechanism that controls the PD-L1 level in tumor cells, suggesting an alternative strategy to improve the efficacy of PD-L1-related immunotherapies.