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SummaryHIV-1 latency results from tightly regulated molecular processes that act at distinct steps of HIV-1 gene expression. Here,we characterize PCI domain-containing 2 (PCID2) protein,a subunit of the transcription and export complex 2 (TREX2) complex,to enforce transcriptional repression and post-transcriptional blocks to HIV-1 gene expression during latency. PCID2 bound the latent HIV-1 LTR (long terminal repeat) and repressed transcription initiation during latency. Depletion of PCID2 remodeled the chromatin landscape at the HIV-1 promoter and resulted in transcriptional activation and latency reversal. Immunoprecipitation coupled to mass spectrometry identified PCID2-interacting proteins to include negative viral RNA (vRNA) splicing regulators,and PCID2 depletion resulted in over-splicing of intron-containing vRNA in cell lines and primary cells obtained from PWH. MCM3AP and DSS1,two other RNA-binding TREX2 complex subunits,also inhibit transcription initiation and vRNA alternative splicing during latency. Thus,PCID2 is a novel HIV-1 latency-promoting factor,which in context of the TREX2 sub-complex PCID2-DSS1-MCM3AP blocks transcription and dysregulates vRNA processing. Graphical abstract Highlights•PCID2 is bound to the latent HIV-1 LTR as a transcriptional repressor•PCID2 enforces latency by acting on transcription initiation•PCID2 establishes blocks to alternative splicing during HIV-1 latency•PCID2 misregulates alternative splicing in cells obtained from people with HIV-1 Virology; Cell biology View Publication

Although FOXP3+ regulatory T cells (Treg) depend on IL-2 produced by other cells for their survival and function,the levels of IL-2 in inflamed tissue are low,making it unclear how Treg access this critical resource. Here,we show that Treg use heparanase (HPSE) to access IL-2 sequestered by heparan sulfate (HS) within the extracellular matrix (ECM) of inflamed central nervous system tissue. HPSE expression distinguishes human and murine Treg from conventional T cells and is regulated by the availability of IL-2. HPSE-/- Treg have impaired stability and function in vivo,including in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis. Conversely,endowing monoclonal antibody-directed chimeric antigen receptor (mAbCAR) Treg with HPSE enhances their ability to access HS-sequestered IL-2 and their ability to suppress neuroinflammation in vivo. Together,these data identify a role for HPSE and the ECM in immune tolerance,providing new avenues for improving Treg-based therapy of autoimmunity. Regulatory T cell (Treg) maintenance and function require IL-2,yet this cytokine is only present in low levels in vivo. In this study,the authors demonstrate that that Treg use heparanase to access IL-2 bound to heparan sulfate proteoglycans in the extracellular matrix of inflamed brain tissue in mice. View Publication

AbstractBackgroundAcute graft‐versus‐host disease (aGVHD) arises from the imbalance of host T cells. Galectin‐9 negatively regulates CD4 effector T cell (Th1 and Th17) function by binding to Tim‐3. However,the relationship between Galectin‐9/Tim‐3 and CD4+ T subsets in patients with aGVHD after Haplo‐HSCT (haploidentical peripheral blood hematopoietic stem cell transplantation) has not been fully elucidated. Here,we investigated the role of Galectin‐9 and CD4+T subsets in aGVHD after haplo‐HSCT.MethodsForty‐two patients underwent Haplo‐HSCT (26 without aGVHD and 16 with aGVHD),and 20 healthy controls were included. The concentrations of Galectin‐9,interferon‐gamma (IFN‐γ),interleukin (IL)‐4,transforming growth factor (TGF)‐β,and IL‐17 in the serum and culture supernatant were measured using enzyme‐linked immunosorbent assay or cytometric bead array. The expression levels of Galectin‐9,PI3K,p‐PI3K,and p‐mTOR protein were detected by western blot analysis. Flow cytometry was used to analyze the proportions of CD4+ T cell subsets. Bioinformatics analysis was performed.ResultsIn patients with aGVHD,regulatory T (Treg) cells and Galectin‐9 decreased,and the Th1,Th17,and Treg cells were significantly imbalanced. Moreover,Treg and Galectin‐9 were rapidly reconstituted in the early stage of patients without aGVHD after Haplo‐HSCT,but Th17 cells were reconstituted slowly. Furthermore,Tim‐3 upregulation on Th17 and Th1 cells was associated with excessive activation of the PI3K/AKT pathway in patients with aGVHD. Specifically,in vitro treatment with Galectin‐9 reduced IFN‐γ and IL‐17 production while augmenting TGF‐β secretion. Bioinformatics analysis suggested the potential involvement of the PI3K/AKT/mTOR pathway in aGVHD. Mechanistically,exogenous Galectin‐9 was found to mitigate aGVHD by restoring the Treg/Teffs (effector T cells) balance and suppressing PI3K.ConclusionGalectin‐9 may ameliorate aGVHD after haplo‐HSCT by modulating Treg/Teffs balance and regulating the PI3K/AKT/mTOR pathway. Targeting Galectin‐9 may hold potential value for the treatment of aGVHD. In patients with acute graft‐versus‐host disease (aGVHD),the expression of Tim‐3 is significantly increased. Galectin‐9 binding to Tim‐3 may inhibit the activation of the PI3K/AKT pathway and enhance the function of Treg cells. On the other hand,transforming growth factor (TGF)‐β promotes the differentiation of Treg cells through autocrine secretion,while TGF‐β induces the expression of Galectin‐9 in a paracrine manner. The increased Treg cells can inhibit the activation of Th1 and Th17 cells by secreting TGF‐β,thus alleviating aGVHD and inducing immune tolerance View Publication

BackgroundSevere peripheral nerve damage always requires surgical treatment. Autologous nerve transplantation is a standard treatment,but it is not sufficient due to length limitations and extended surgical time. Even with the available artificial nerves,there is still large room for improvement in their therapeutic effects. Novel treatments for peripheral nerve injury are greatly expected.MethodsUsing a specialized microfluidic device,we generated artificial neurite bundles from human iPSC-derived motor and sensory nerve organoids. We developed a new technology to isolate cell-free neurite bundles from spheroids. Transplantation therapy was carried out for large nerve defects in rat sciatic nerve with novel artificial nerve conduit filled with lineally assembled sets of human neurite bundles. Quantitative comparisons were performed over time to search for the artificial nerve with the therapeutic effect,evaluating the recovery of motor and sensory functions and histological regeneration. In addition,a multidimensional unbiased gene expression profiling was carried out by using next-generation sequencing.ResultAfter transplantation,the neurite bundle-derived artificial nerves exerted significant therapeutic effects,both functionally and histologically. Remarkably,therapeutic efficacy was achieved without immunosuppression,even in xenotransplantation. Transplanted neurite bundles fully dissolved after several weeks,with no tumor formation or cell proliferation,confirming their biosafety. Posttransplant gene expression analysis highlighted the immune system’s role in recovery.ConclusionThe combination of newly developed microfluidic devices and iPSC technology enables the preparation of artificial nerves from organoid-derived neurite bundles in advance for future treatment of peripheral nerve injury patients. A promising,safe,and effective peripheral nerve treatment is now ready for clinical application.Supplementary InformationThe online version contains supplementary material available at 10.1186/s41232-024-00319-4. View Publication

The maturation process of natural killer (NK) cells,which is regulated by multiple transcription factors,determines their functionality,but few checkpoints specifically targeting this process have been thoroughly studied. Here we show that NK-specific deficiency of glucose-regulated protein 94 (gp96) leads to decreased maturation of NK cells in mice. These gp96-deficient NK cells exhibit undermined activation,cytotoxicity and IFN-γ production upon stimulation,as well as weakened responses to IL-15 for NK cell maturation,in vitro. In vivo,NK-specific gp96-deficient mice show increased tumor growth. Mechanistically,we identify Eomes as the downstream transcription factor,with gp96 binding to Trim28 to prevent Trim28-mediated ubiquitination and degradation of Eomes. Our study thus suggests the gp96-Trim28-Eomes axis to be an important regulator for NK cell maturation and cancer surveillance in mice. Natural killer (NK) cell maturation and function are regulated by multiple transcription factors (TF),but detailed molecular insights are scarce. Here the authors show that a TF,Eomes,is important for NK cell responses and cancer surveillance,in which Eomes expression is regulated by gp96 and Trim28 via the ubiquitination and degradation pathways. View Publication

Staphylococcus aureus is a notorious human pathogen that thrives in macrophages. It resides in mature phagolysosomes,where a subset of the bacteria eventually begin to proliferate. How S. aureus acquires essential nutrients,such as amino acids,for growth in this niche is poorly understood. Using a long-term primary human macrophage infection model,we show that branched-chain amino acid (BCAA) uptake mediated by the major transporter BrnQ1 is required by S. aureus for intracellular replication in macrophages and we provide mechanistic insight into the role of BCAAs in the success of intracellular S. aureus. Loss of BrnQ1 function renders intracellular S. aureus non-replicative and non-cytotoxic. The defective intracellular growth of S. aureus brnQ1 mutants can be rescued by supplementation with BCAAs or by overexpression of the BCAA transporters BrnQ1 or BcaP. Inactivation of the CodY repressor rescues the ability of S. aureus brnQ1 mutants to proliferate intracellularly independent of endogenous BCAA synthesis but dependent on BcaP expression. Non-replicating brnQ1 mutants in primary human macrophages become metabolically quiescent and display aberrant gene expression marked by failure to respond to intraphagosomal iron starvation. The bacteria remain,however,viable for an inordinate length of time. This dormant,yet viable bacterial state is distinct from classical persisters and small colony variants. Author summaryStaphylococcus aureus is a prominent human pathogen causing acute and chronic disease. It is facultatively intracellular and can reside within many host cell types,including professional phagocytes such as macrophages. The intracellular state contributes to dissemination,recurrence and infection chronicity. Chronic and relapsing infections are often associated with so-called persister phenotypes. Growth arrest and metabolic quiescence,accompanied by antibiotic tolerance,are hallmarks of persistence in bacteria. Antibiotic pressure is a major factor in triggering intracellular persistence. The small colony variant (SCV),an extensively studied form of S. aureus persister,can arise in the absence of antibiotic pressure and exhibits very distinctive phenotypic characteristics.Here,we describe a different growth-arrested state of S. aureus,which conforms to the definition of a non-antibiotic-driven form of intracellular dormancy,triggered by branched-chain amino acid starvation in macrophages. We show that loss of function of the major branched-chain amino acid transporter BrnQ1 renders intracellular S. aureus non-replicative and metabolically quiescent for an inordinate period of time. Upon stochastic exit from infected macrophages,brnQ1 mutants retain full virulence. This dormancy differs from classical persistence or SCVs and uncovers an underestimated role for BCAA uptake in the success of intracellular S. aureus. View Publication

AbstractBackgroundPatients with head and neck squamous cell carcinoma (HNSCC),particularly the human papillomavirus negative (HPV−) subset,have a dismal prognosis. Furthermore,patients with Fanconi anemia (FA) have a genetic predisposition with a 500-fold to 700-fold higher incidence of HNSCC. Thus,novel and more efficacious therapies are needed. As current immunotherapies often fail due to suppressive elements in the tumor microenvironment (TME),we developed a trispecific killer engager (TriKE) to direct multiple signals to natural killer (NK) cells to overcome the hypoxic TME. This TriKE is comprised of a camelid nanobody that binds to CD16 on NK cells,an interleukin (IL)-15 moiety,and another novel camelid nanobody that binds to the B7-H3 antigen,which is highly and specifically expressed on the tumor cell surface.MethodsThe B7H3 TriKE was generated using a mammalian expression system. Its functionality was evaluated using flow cytometry-based NK cell degranulation,cytokine production,proliferation and live cell imaging cytotoxicity assays. Models of acute and prolonged hypoxia (1% oxygen) were carried out to assess tumor killing. Tumor progression,NK cell persistence,and survival differences between IL-15-treated and TriKE-treated mice were studied using NOD-scidIL2Rgnull (NSG) mice engrafted with human HNSCC.ResultsHigh B7-H3 expression was found in HPV− HNSCC cell lines,even when the FA gene was knocked out,and The Cancer Genome Atlas patient data showed that high B7-H3 expression predicted poor survival in patients with HPV− HNSCC. Similar to the NK cell activity seen with healthy donors,the B7H3 TriKE enhanced activation,expansion and cytotoxicity of NK cells from patients with HPV− HNSCC,a target population for this therapeutic. Additionally,the B7H3 TriKE improved NK cell cytotoxicity in a three-dimensional spheroid model of HNSCC. In both acute and prolonged hypoxia (1% oxygen),the B7H3 TriKE mediated enhanced tumor killing,mitigating impairment of NK cell cytotoxicity in hypoxia. In vivo,the B7H3 TriKE-treated mice demonstrated substantial antitumor activity and prolonged survival.ConclusionsThe B7H3 TriKE is a novel immunotherapeutic approach that can overcome hypoxic suppression of NK cells in the HNSCC TME. These highly translational studies present an innovative therapy for patients with HNSCC and will be developed further for clinical application. View Publication

SummaryInterleukin-33 (IL-33) is an immunoregulatory cytokine that moderately suppresses experimental autoimmune encephalomyelitis (EAE),a murine model of multiple sclerosis (MS). However,poor pharmacokinetics and toxicity hinder its clinical translation. To address these limitations,we develop an activity-attenuated IL-33 by recombinant fusion to serum albumin (SA). SA-IL-33 exhibits reduced toxicity and prolonged residence in the secondary lymphoid organs (SLOs),sites of T cell priming in autoimmunity,compared to wild-type (WT) IL-33. Prophylactic SA-IL-33 administration prevents EAE with superior efficacy to WT IL-33 and comparable efficacy to fingolimod (FTY720),a Food and Drug Administration (FDA)-approved MS drug. Therapeutic SA-IL-33 treatment also reduces disease severity in both chronic and relapsing-remitting EAE. SA-IL-33 modulates immunity in EAE by suppressing CD45+ cell infiltration (including myelin-reactive T helper 17 [TH17] cells) in the spinal cord,while expanding type 2 immune cells (including type 2 innate lymphoid cells [ILC2s],ST2+ regulatory T cells [Tregs],T helper 2 [TH2] cells,and M2-polarized macrophages) in the SLOs. These findings suggest that SA-IL-33 is a promising therapeutic for neuroinflammatory diseases. Graphical abstract Highlights•Fusion of serum albumin (SA) to interleukin-33 (IL-33) attenuates its activity and toxicity•Engineered SA-IL-33 exhibits prolonged residence in the secondary lymphoid organs (SLOs)•SA-IL-33 treatment both prevents the onset of and reduces established neuroinflammation in mice•Cytokine therapy suppresses TH17 cells in the CNS and promotes immunoregulation in the SLOs The clinical utility of interleukin-33 is hindered by poor pharmacokinetics and toxicity. Budina et al. develop a fusion of serum albumin and interleukin-33 (SA-IL-33) with reduced toxicity and prolonged lymph node residence. SA-IL-33 prevents the onset of and suppresses established inflammation-mediated paralysis in mice,demonstrating promise as a therapeutic for neuroinflammatory diseases. View Publication

SummaryAlthough chimeric antigen receptor (CAR) T cells have demonstrated therapeutic activity in hematopoietic malignancies,tumor heterogeneity has impeded the efficacy of CAR T cells and their extension into successful solid tumor treatment. To address these challenges,induced pluripotent stem cell (iPSC)-derived T (iT) cells are engineered to uniformly express CAR and T cell receptor (TCR),enabling targeting of both surface and intracellular antigens,respectively,along with a high-affinity,non-cleavable variant of CD16a (hnCD16) to support antibody-dependent cellular cytotoxicity (ADCC) when combined with therapeutic antibodies. Co-expression of each antitumor strategy on engineered iT cells enables independent and antigen-specific targeting across a diverse set of liquid and solid tumors. In heterogeneous tumor models,coactivation of these modalities is required for measurable antitumor efficacy,with activation of all three modalities displaying maximal efficacy. These data highlight the therapeutic potential of an off-the-shelf engineered iPSC-derived trimodal T cell expressing CAR,TCR,and hnCD16 to combat difficult-to-treat heterogeneous tumors. Graphical abstract Highlights•CAR,TCR,and hnCD16 can be uniformly co-expressed and can function in iT cells•hnCD16 signals through CD3ζ and arms iT cells with targeting flexibility through ADCC•Concurring CAR,TCR,and hnCD16 activation demonstrates a cooperative effect•Multi-targeting with trimodal iT cells can control heterogeneous tumors in vivo Yang et al. show that (1) trimodal iPSC cells expressing CAR,TCR,and hnCD16 can commit to T cell lineage,(2) hnCD16 signals through CD3ζ in iT cells and arms iT cells with ADCC targeting flexibility,and (3) trimodal iT cells control antigen-heterogeneous tumors in vivo through multi-modal targeting. View Publication

SummarymRNA-based in vivo chimeric antigen receptor (CAR)-T cell engineering offers advantages over ex vivo therapies,including streamlined manufacturing and transient expression. However,current delivery methods require antibody-modified vehicles with manufacturing challenges. In this study,inspired by cardiolipin,we identify cardiolipin-like di-phosphoramide lipids that improve T cell transfection without targeting ligands,both in vitro and in vivo. The T cell-favored tropism is likely due to the lipid’s packing,shape,and rigidity. Encapsulating circular RNA further prolongs mRNA expression in the spleen and T cells. Using PL40 lipid nanoparticles,we deliver mRNA encoding a CAR targeting the senolytic and inflammatory antigen urokinase-type plasminogen activator receptor (uPAR),alleviating uPAR-related liver fibrosis and rheumatoid arthritis (RA). Single-cell sequencing in humans confirms uPAR’s relevance to senescence and inflammation in RA. To facilitate clinical translation,we screen and humanize single-chain variable fragments (scFvs) against uPAR,establishing a PL40 mRNA-encoded humanized uPAR CAR with potential for treating aging-inflamed disorders. Graphical abstract Highlights•Cardiolipin-mimic phosphoramide (CAMP) LNPs transfect T cells without antibody modification•Circular mRNA prolongs mRNA expression•Senolytic in vivo CAR-T treats inflamm-aging disease (liver fibrosis and rheumatoid arthritis)•Develop humanized anti-human uPAR scFv Zhang et al. develop Cardiolipin-mimic phosphoramide (CAMP) lipids,which enable T cell transfection without antibody modification. Using CAMP-based LNPs,they generate senolytic CAR-T cells in vivo to target inflamm-aging diseases. Additionally,they employ circular mRNA to prolong transgene expression. The authors also engineer a humanized anti-human uPAR scFv for clinically relevant applications. View Publication

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques and neurofibrillary tangles composed of hyperphosphorylated tau protein. The combination of biomarkers is crucial for AD diagnosis. The triggering receptor expressed on myeloid cells 2 (TREM2),a receptor expressed on microglia,is important in AD pathogenesis. Impairment of TREM2 function aggravates the toxic effects of amyloid plaques,and its activation has been shown to reduce Aβ burden and memory deficits. Increased levels of soluble TREM2 (sTREM2) in blood and cerebrospinal fluid is associated with AD. Therefore,TREM2 could serve as a non-invasive biomarker for AD. In this study,we developed a preclinical immunoassay to detect TREM2 for AD diagnosis. Highly sensitive and specific TREM2 antibodies were produced using the hybridoma technique. The three optimized immunoassays exhibited lower limit of quantitation (LLOQ) of 0.474,0.807,and 0.415 ng/mL,respectively. These preclinical immunoassays showed high sensitivity and specificity. The sandwich enzyme-linked immunosorbent assay (ELISA) could potentially be used for AD diagnosis. View Publication

Macrophages play vital roles in innate and adaptive immunity,and their functions are mediated via phagocytosis and antigen presentation. Despite the effort to identify phagocytic checkpoints and explore their mechanism of action,current checkpoint-scanning strategies cannot provide a complete and systematic list of such immune checkpoints. Here,we perform in vitro phagocytosis assays using primary healthy donor macrophages co-cultured with breast cancer cells followed by ribosome profiling of sorted macrophages,to identify immune system-specific checkpoints. We observe a downregulation of CD37 in phagocytic macrophages and demonstrate that targeting CD37 with a specific antibody promotes the phagocytosis of multiple cancer cells in vitro. Mechanistically,tumorous macrophage migration inhibitory factor (MIF) directly binds to CD37,promoting the phosphorylation of CD37Y13 and activating a transduction cascade that involves the recruitment of SHP1 and inhibition of AKT signaling,ultimately impairing phagocytosis. In vivo,targeting CD37 promotes tumor clearance in multiple preclinical mouse models and synergizes with anti-CD47 therapy. Thus,our study identifies a previously unidentified phagocytic checkpoint and provides new potential for precise therapy. Cancer cells evade the immune system by disrupting phagocytic clearance. Here,the authors identify CD37 as a potential checkpoint molecule expressed on non-phagocytes and propose that binding to tumor-derived MIF reduces the phagocytic ability via inhibiting the AKT pathway. In preclinical mouse models,anti-CD37-based therapy enhances phagocytosis by macrophages,facilitating tumor clearance. View Publication