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T cell exhaustion presents one of the major hurdles to cancer immunotherapy. Among exhausted CD8 + tumor-infiltrating lymphocytes, the terminally exhausted subset contributes directly to tumor cell killing owing to its cytotoxic effector function. However, this subset does not respond to immune checkpoint blockades and is difficult to be reinvigorated with restored proliferative capacity. Here, we show that a half-life-extended interleukin-10–Fc fusion protein directly and potently enhanced expansion and effector function of terminally exhausted CD8 + tumor-infiltrating lymphocytes by promoting oxidative phosphorylation, a process that was independent of the progenitor exhausted T cells. Interleukin-10–Fc was a safe and highly efficient metabolic intervention that synergized with adoptive T cell transfer immunotherapy, leading to eradication of established solid tumors and durable cures in the majority of treated mice. These findings show that metabolic reprogramming by upregulating mitochondrial pyruvate carrier-dependent oxidative phosphorylation can revitalize terminally exhausted T cells and enhance the response to cancer immunotherapy. Tang and colleagues show that a half-life-extended IL-10–Fc fusion protein acts directly on terminally exhausted PD1 + TIM-3 + CD8 + T cells to enhance their proliferation and effector function by reprogramming the cellular metabolism to oxidative phosphorylation in a mitochondrial pyruvate carrier–dependent manner. Treatment of tumor-bearing mice with IL-10–Fc and adoptive T cell therapy led to eradication of their established solid tumors and durable cures.

Cytotoxic T cells and natural killer cells use several strategies to kill infected or transformed cells. One such pathway entails the delivery of a family of serine proteases called granzymes to target cells through perforin-mediated pores to induce a form of programmed cell death called apoptosis. Zhou et al. show that granzyme A cleaves and activates gasdermin B (GSDMB), a central player in the highly inflammatory cell death process known as pyroptosis (see the Perspective by Nicolai and Raulet). GSDMB expression was highly expressed in some tissues and could be up-regulated by interferon-γ. Enforced expression of GSDMB in cancer cells enhanced tumor clearance in a mouse model, suggesting that this pathway may be a target for future cancer immunotherapies. Science , this issue p. eaaz7548 ; see also p. 943 Cytotoxic lymphocytes use granzyme A to cleave gasdermin B and induce pyroptosis in target cells. Cytotoxic lymphocyte–mediated immunity relies on granzymes. Granzymes are thought to kill target cells by inducing apoptosis, although the underlying mechanisms are not fully understood. Here, we report that natural killer cells and cytotoxic T lymphocytes kill gasdermin B (GSDMB)–positive cells through pyroptosis, a form of proinflammatory cell death executed by the gasdermin family of pore-forming proteins. Killing results from the cleavage of GSDMB by lymphocyte-derived granzyme A (GZMA), which unleashes its pore-forming activity. Interferon-γ (IFN-γ) up-regulates GSDMB expression and promotes pyroptosis. GSDMB is highly expressed in certain tissues, particularly digestive tract epithelia, including derived tumors. Introducing GZMA-cleavable GSDMB into mouse cancer cells promotes tumor clearance in mice. This study establishes gasdermin-mediated pyroptosis as a cytotoxic lymphocyte–killing mechanism, which may enhance antitumor immunity.

The efficacy of programmed cell death protein 1 (PD-1) blockade in metastatic triple-negative breast cancer (TNBC) is low 1 – 5 , highlighting a need for strategies that render the tumor microenvironment more sensitive to PD-1 blockade. Preclinical research has suggested immunomodulatory properties for chemotherapy and irradiation 6 – 13 . In the first stage of this adaptive, non-comparative phase 2 trial, 67 patients with metastatic TNBC were randomized to nivolumab (1) without induction or with 2-week low-dose induction, or with (2) irradiation (3 × 8 Gy), (3) cyclophosphamide, (4) cisplatin or (5) doxorubicin, all followed by nivolumab. In the overall cohort, the objective response rate (ORR; iRECIST 14 ) was 20%. The majority of responses were observed in the cisplatin (ORR 23%) and doxorubicin (ORR 35%) cohorts. After doxorubicin and cisplatin induction, we detected an upregulation of immune-related genes involved in PD-1–PD-L1 (programmed death ligand 1) and T cell cytotoxicity pathways. This was further supported by enrichment among upregulated genes related to inflammation, JAK–STAT and TNF-α signaling after doxorubicin. Together, the clinical and translational data of this study indicate that short-term doxorubicin and cisplatin may induce a more favorable tumor microenvironment and increase the likelihood of response to PD-1 blockade in TNBC. These data warrant confirmation in TNBC and exploration of induction treatments prior to PD-1 blockade in other cancer types. A pick-the-winner clinical trial design in patients with metastatic triple-negative breast cancer shows that immune induction with doxorubicin or cisplatin may improve clinical responses to PD-1 blockade and induce a more favorable tumor microenvironment.

CD8 + cytotoxic T cells (CTLs) orchestrate antitumour immunity and exhibit inherent heterogeneity 1 , 2 , with precursor exhausted T (T pex ) cells but not terminally exhausted T (T ex ) cells capable of responding to existing immunotherapies 3 – 7 . The gene regulatory network that underlies CTL differentiation and whether T ex cell responses can be functionally reinvigorated are incompletely understood. Here we systematically mapped causal gene regulatory networks using single-cell CRISPR screens in vivo and discovered checkpoints for CTL differentiation. First, the exit from quiescence of T pex cells initiated successive differentiation into intermediate T ex cells. This process is differentially regulated by IKAROS and ETS1, the deficiencies of which dampened and increased mTORC1-associated metabolic activities, respectively. IKAROS-deficient cells accumulated as a metabolically quiescent T pex cell population with limited differentiation potential following immune checkpoint blockade (ICB). Conversely, targeting ETS1 improved antitumour immunity and ICB efficacy by boosting differentiation of T pex to intermediate T ex cells and metabolic rewiring. Mechanistically, TCF-1 and BATF are the targets for IKAROS and ETS1, respectively. Second, the RBPJ–IRF1 axis promoted differentiation of intermediate T ex to terminal T ex cells. Accordingly, targeting RBPJ enhanced functional and epigenetic reprogramming of T ex cells towards the proliferative state and improved therapeutic effects and ICB efficacy. Collectively, our study reveals that promoting the exit from quiescence of T pex cells and enriching the proliferative T ex cell state act as key modalities for antitumour effects and provides a systemic framework to integrate cell fate regulomes and reprogrammable functional determinants for cancer immunity. Analyses of causal gene regulatory networks have identified key checkpoints mediating the progressive differentiation of CD8 + cytotoxic T cells, findings that have implications for anticancer immunotherapies such as adoptive cell therapy and immune checkpoint blockade.

Cytotoxic lymphocyte-derived granzyme A (GZMA) cleaves GSDMB, a gasdermin-family pore-forming protein 1 , 2 , to trigger target cell pyroptosis 3 . GSDMB and the charter gasdermin family member GSDMD 4 , 5 have been inconsistently reported to be degraded by the Shigella flexneri ubiquitin-ligase virulence factor IpaH7.8 (refs. 6 , 7 ). Whether and how IpaH7.8 targets both gasdermins is undefined, and the pyroptosis function of GSDMB has even been questioned recently 6 , 8 . Here we report the crystal structure of the IpaH7.8–GSDMB complex, which shows how IpaH7.8 recognizes the GSDMB pore-forming domain. We clarify that IpaH7.8 targets human (but not mouse) GSDMD through a similar mechanism. The structure of full-length GSDMB suggests stronger autoinhibition than in other gasdermins 9 , 10 . GSDMB has multiple splicing isoforms that are equally targeted by IpaH7.8 but exhibit contrasting pyroptotic activities. Presence of exon 6 in the isoforms dictates the pore-forming, pyroptotic activity in GSDMB. We determine the cryo-electron microscopy structure of the 27-fold-symmetric GSDMB pore and depict conformational changes that drive pore formation. The structure uncovers an essential role for exon-6-derived elements in pore assembly, explaining pyroptosis deficiency in the non-canonical splicing isoform used in recent studies 6 , 8 . Different cancer cell lines have markedly different isoform compositions, correlating with the onset and extent of pyroptosis following GZMA stimulation. Our study illustrates fine regulation of GSDMB pore-forming activity by pathogenic bacteria and mRNA splicing and defines the underlying structural mechanisms. The cryo-EM structure of the GSDMB pore reveals mechanisms by which GSDMB pore-forming activity is regulated by pathogenic bacteria and mRNA splicing.

Immunotherapy with immune‐checkpoint therapy has recently been used to treat oral squamous cell carcinomas (OSCCs). However, improvements in current immunotherapy are expected because response rates are limited. Transforming growth factor‐β (TGF‐β) creates an immunosuppressive tumor microenvironment (TME) by inducing the production of regulatory T‐cells (Tregs) and cancer‐associated fibroblasts and inhibiting the function of cytotoxic T‐lymphocytes (CTLs) and natural killer cells. TGF‐β may be an important target in the development of novel cancer immunotherapies. In this study, we investigated the suppressive effect of TGF‐β on CTL function in vitro using OSCC cell lines and their specific CTLs. Moreover, TGFB1 mRNA expression and T‐cell infiltration in 25 OSCC tissues were examined by in situ hybridization and multifluorescence immunohistochemistry. We found that TGF‐β suppressed the function of antigen‐specific CTLs in the priming and effector phases in vitro. Additionally, TGF‐β inhibitor effectively restored the CTL function, and TGFB1 mRNA was primarily expressed in the tumor invasive front. Interestingly, we found a significant negative correlation between TGFB1 mRNA expression and the CD8+ T‐cell/Treg ratio and between TGFB1 mRNA expression and the Ki‐67 expression in CD8+ T‐cells, indicating that TGF‐β also suppressed the function of CTLs in situ. Our findings suggest that the regulation of TGF‐β function restores the immunosuppressive TME to active status and is important for developing new immunotherapeutic strategies, such as a combination of immune‐checkpoint inhibitors and TGF‐β inhibitors, for OSCCs. We found that, TGF‐β suppressed the function of antigen‐specific CTLs in the priming and effector phases in vitro. And, we found a significant negative correlation between TGFB1 mRNA expression and the CD8+ T‐cell/Treg ratio. Inhibition of TGF‐β restores the immunosuppressive TME to active status by a mechanism different from that of immune‐checkpoint inhibitors, suggesting that the combination of both may lead to a new therapeutic strategy for OSCCs.

Antimicrobial peptides (AMPs) play a key role in the innate immunity, the first line of defense against bacteria, fungi, and viruses. AMPs are small molecules, ranging from 10 to 100 amino acid residues produced by all living organisms. Because of their wide biodiversity, insects are among the richest and most innovative sources for AMPs. In particular, the insect Hermetia illucens (Diptera: Stratiomyidae) shows an extraordinary ability to live in hostile environments, as it feeds on decaying substrates, which are rich in microbial colonies, and is one of the most promising sources for AMPs. The larvae and the combined adult male and female H. illucens transcriptomes were examined, and all the sequences, putatively encoding AMPs, were analysed with different machine learning-algorithms, such as the Support Vector Machine, the Discriminant Analysis, the Artificial Neural Network, and the Random Forest available on the CAMP database, in order to predict their antimicrobial activity. Moreover, the iACP tool, the AVPpred, and the Antifp servers were used to predict the anticancer, the antiviral, and the antifungal activities, respectively. The related physicochemical properties were evaluated with the Antimicrobial Peptide Database Calculator and Predictor. These analyses allowed to identify 57 putatively active peptides suitable for subsequent experimental validation studies.

Interferon gamma (IFN γ ) is a key moderator of cell-mediated immunity with diverse, mainly pro-inflammatory actions on immunocytes and target tissue. Recent studies have shown it may enhance anti-tumor and antiviral effects of CD8 T cells. Here we investigate the mechanisms by which IFN γ mediates CD8 T-cell cytotoxic function. We show that in vivo , antigen-specific CD8 T cells that produce INF γ are necessary to effect rejection of skin grafts expressing OVA as a transgene in keratinocytes. The ability of CD8 T cells to produce IFN γ enhanced their ability to migrate to the site of antigen-presenting skin cells. By in vivo imaging, we show that CTL motility, particularly speed, during graft rejection was enhanced by locally available IFN γ . We then used a reductionist two-cell model of CTL effectors and keratinocyte targets to investigate the effects of locally available (paracrine) and CTL-producing (autocrine) IFN γ on the motility behavior and killing ability of the CTL. Using live-cell imaging by prolonged time-lapse microscopy of primary effector CD8 T cells and antigen-expressing primary keratinocyte targets, we show that CD8 T-cell cytotoxic function and motility is enhanced by locally available IFN γ . Conversely, deprivation of either autocrine or paracrine IFN γ , or blockade of IFN γ signaling to CTL markedly reduced their cytotoxic function, their kinematics, and effector cell survival. We conclude that in vitro and in vivo, autocrine production of IFN γ by CTL enhances their motility and promotes killing of primary target keratinocytes. The absolute need for local IFN γ to enable cytotoxic CD8 T-cell function is of significance for immunotherapy for chronic viral infection and for cancer.

Extracellular deposition of amyloid-β as neuritic plaques and intracellular accumulation of hyperphosphorylated, aggregated tau as neurofibrillary tangles are two of the characteristic hallmarks of Alzheimer’s disease 1 , 2 . The regional progression of brain atrophy in Alzheimer’s disease highly correlates with tau accumulation but not amyloid deposition 3 – 5 , and the mechanisms of tau-mediated neurodegeneration remain elusive. Innate immune responses represent a common pathway for the initiation and progression of some neurodegenerative diseases. So far, little is known about the extent or role of the adaptive immune response and its interaction with the innate immune response in the presence of amyloid-β or tau pathology 6 . Here we systematically compared the immunological milieux in the brain of mice with amyloid deposition or tau aggregation and neurodegeneration. We found that mice with tauopathy but not those with amyloid deposition developed a unique innate and adaptive immune response and that depletion of microglia or T cells blocked tau-mediated neurodegeneration. Numbers of T cells, especially those of cytotoxic T cells, were markedly increased in areas with tau pathology in mice with tauopathy and in the Alzheimer’s disease brain. T cell numbers correlated with the extent of neuronal loss, and the cells dynamically transformed their cellular characteristics from activated to exhausted states along with unique TCR clonal expansion. Inhibition of interferon-γ and PDCD1 signalling both significantly ameliorated brain atrophy. Our results thus reveal a tauopathy- and neurodegeneration-related immune hub involving activated microglia and T cell responses, which could serve as therapeutic targets for preventing neurodegeneration in Alzheimer’s disease and primary tauopathies. A study finds T cells in areas of tau, not amyloid, pathology in Alzheimer’s disease brain and mouse models, with their presence correlating with neuronal loss and their depletion, or that of microglia, preventing neurodegeneration and cognitive decline.

The two T cell inhibitory receptors PD-1 and TIM-3 are co-expressed during exhausted T cell differentiation, and recent evidence suggests that their crosstalk regulates T cell exhaustion and immunotherapy efficacy; however, the molecular mechanism is unclear. Here we show that PD-1 contributes to the persistence of PD-1 + TIM-3 + T cells by binding to the TIM-3 ligand galectin-9 (Gal-9) and attenuates Gal-9/TIM-3-induced cell death. Anti-Gal-9 therapy selectively expands intratumoral TIM-3 + cytotoxic CD8 T cells and immunosuppressive regulatory T cells (T reg cells). The combination of anti-Gal-9 and an agonistic antibody to the co-stimulatory receptor GITR (glucocorticoid-induced tumor necrosis factor receptor-related protein) that depletes T reg cells induces synergistic antitumor activity. Gal-9 expression and secretion are promoted by interferon β and γ, and high Gal-9 expression correlates with poor prognosis in multiple human cancers. Our work uncovers a function for PD-1 in exhausted T cell survival and suggests Gal-9 as a promising target for immunotherapy. Galectin-9 regulates several cellular processes including TIM-3-mediated T cell death. Here the authors show that co-expressed PD-1 protects TIM-3 + T cells from galectin-9-induced cell death and that anti-galectin-9 in combination with GITR agonism promotes an anti-tumor immune response.