Perforin and granzymes: function, dysfunction and human pathology

Case report: Long-term voluntary Tyrosine Kinase Inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML): Molecular evidence of an immune surveillance

The classical natural history of chronic myeloid leukemia (CML) has been drastically modified by the introduction of tyrosine kinase inhibitor (TKI) therapies. TKI discontinuation is currently possible in patients in deep molecular responses, using strict recommendations of molecular follow-up due to risk of molecular relapse, especially during the first 6 months. We report here the case of a patient who voluntarily interrupted her TKI therapy. She remained in deep molecular remission (MR4) for 18 months followed by detection of a molecular relapse at +20 months. Despite this relapse, she declined therapy until the occurrence of the hematological relapse (+ 4 years and 10 months). Retrospective sequential transcriptome experiments and a single-cell transcriptome RNA-seq analysis were performed. They revealed a molecular network focusing on several genes involved in both activation and inhibition of NK-T cell activity. Interestingly, the single-cell transcriptome analysis showed the presence of cells expressing NKG7, a gene involved in granule exocytosis and highly involved in anti-tumor immunity. Single cells expressing as granzyme H, cathepsin-W, and granulysin were also identified. The study of this case suggests that CML was controlled for a long period of time, potentially via an immune surveillance phenomenon. The role of NKG7 expression in the occurrence of treatment-free remissions (TFR) should be evaluated in future studies.

Re-generation of cytotoxic γδT cells with distinctive signatures from human γδT-derived iPSCs

For a long time, ex vivo-expanded peripheral-blood-derived γδT cell (PBγδT)-based immunotherapy has been attractive, and clinical trials have been undertaken. However, the difficulty in expanding cytotoxic γδT cells to an adequate number has been a major limitation to the efficacy of treatment in most cases. We successfully re-generated γδT cells from γδT cell-derived human induced pluripotent stem cells (iPSCs). The iPSC-derived γδT cells (iγδTs) killed several cancer types in a major histocompatibility complex (MHC)-unrestricted manner. Single-cell RNA sequencing (scRNA-seq) revealed that the iγδTs were identical to a minor subset of PBγδTs. Compared with a major subset of PBγδTs, the iγδTs showed a distinctive gene expression pattern: lower CD2, CD5, and antigen-presenting genes; higher CD7, KIT, and natural killer (NK) cell markers. The iγδTs expressed granzyme B and perforin but not interferon gamma (IFNγ). Our data provide a new source for γδT cell-based immunotherapy without quantitative limitation.

Insights into the cellular pathophysiology of familial hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (fHLH) encompasses a group of rare inherited immune dysregulation disorders characterized by loss-of-function mutations in one of several genes involved in the assembly, exocytosis, and function of cytotoxic granules within CD8+ T cells and natural killer (NK) cells. The resulting defect in cytotoxicity allows these cells to be appropriately stimulated in response to an antigenic trigger, and also impairs their ability to effectively mediate and terminate the immune response. Consequently, there is sustained lymphocyte activation, resulting in the secretion of excessive amounts of pro-inflammatory cytokines that further activate other cells of the innate and adaptive immune systems. Together, these activated cells and pro-inflammatory cytokines mediate tissue damage that leads to multi-organ failure in the absence of treatment aimed at controlling hyperinflammation. In this article, we review these mechanisms of hyperinflammation in fHLH at the cellular level, focusing primarily on studies performed in murine models of fHLH that have provided insight into how defects in the lymphocyte cytotoxicity pathway mediate rampant and sustained immune dysregulation.

Kindlin-1 regulates IL-6 secretion and modulates the immune environment in breast cancer models

The adhesion protein Kindlin-1 is over-expressed in breast cancer where it is associated with metastasis-free survival; however, the mechanisms involved are poorly understood. Here, we report that Kindlin-1 promotes anti-tumor immune evasion in mouse models of breast cancer. Deletion of Kindlin-1 in Met-1 mammary tumor cells led to tumor regression following injection into immunocompetent hosts. This was associated with a reduction in tumor infiltrating Tregs. Similar changes in T cell populations were seen following depletion of Kindlin-1 in the polyomavirus middle T antigen (PyV MT)-driven mouse model of spontaneous mammary tumorigenesis. There was a significant increase in IL-6 secretion from Met-1 cells when Kindlin-1 was depleted and conditioned media from Kindlin-1-depleted cells led to a decrease in the ability of Tregs to suppress the proliferation of CD8+ T cells, which was dependent on IL-6. In addition, deletion of tumor-derived IL-6 in the Kindlin-1-depleted tumors reversed the reduction of tumor-infiltrating Tregs. Overall, these data identify a novel function for Kindlin-1 in regulation of anti-tumor immunity, and that Kindlin-1 dependent cytokine secretion can impact the tumor immune environment.

Immunotargeting of Cancer Stem Cells

The generally accepted view is that CSCs hijack the signaling pathways attributed to normal stem cells that regulate the self-renewal and differentiation processes. Therefore, the development of selective targeting strategies for CSC, although clinically meaningful, is associated with significant challenges because CSC and normal stem cells share many important signaling mechanisms for their maintenance and survival. Furthermore, the efficacy of this therapy is opposed by tumor heterogeneity and CSC plasticity. While there have been considerable efforts to target CSC populations by the chemical inhibition of the developmental pathways such as Notch, Hedgehog (Hh), and Wnt/β-catenin, noticeably fewer attempts were focused on the stimulation of the immune response by CSC-specific antigens, including cell-surface targets. Cancer immunotherapies are based on triggering the anti-tumor immune response by specific activation and targeted redirecting of immune cells toward tumor cells. This review is focused on CSC-directed immunotherapeutic approaches such as bispecific antibodies and antibody-drug candidates, CSC-targeted cellular immunotherapies, and immune-based vaccines. We discuss the strategies to improve the safety and efficacy of the different immunotherapeutic approaches and describe the current state of their clinical development.

Serpin B9 controls tumor cell killing by CAR T cells

BACKGROUND

Initial clinical responses with gene engineered chimeric antigen receptor (CAR) T cells in cancer patients are highly encouraging; however, primary resistance and also relapse may prevent durable remission in a substantial part of the patients. One of the underlying causes is the resistance mechanisms in cancer cells that limit effective killing by CAR T cells. CAR T cells exert their cytotoxic function through secretion of granzymes and perforin. Inhibition of granzyme B (GrB) can underlie resistance to T cell-mediated killing, and it has been shown that serine proteinase inhibitor serpin B9 can effectively inhibit GrB. We aimed to determine whether expression of serpin B9 by cancer cells can lead to resistance toward CAR T cells.

METHODS

Serpin B9 gene and protein expression were examined by R2 or DepMap database mining and by western blot or flow cytometric analysis, respectively. Coculture killing experiments were performed with melanoma cell line MeWo, diffuse large B cell lymphoma (DLBCL) cell line OCI-Ly7 or primary chronic lymphocytic leukemia (CLL) cells as target cells and natural killer cell line YT-Indy, CD20 CAR T cells or CD19 CAR T cells as effector cells and analyzed by flow cytometry.

RESULTS

Serpin B9 protein expression was previously shown to be associated with clinical outcome in melanoma patients and in line with these observations we demonstrate that enforced serpin B9 expression in melanoma cells reduces sensitivity to GrB-mediated killing. Next, we examined serpin B9 expression in a wide array of primary tumor tissues and human cell lines to find that serpin B9 is uniformly expressed in B-cell lymphomas and most prominently in DLBCL and CLL. Subsequently, using small interfering RNA, we silenced serpin B9 expression in DLBCL cells, which increased their sensitivity to CD20 CAR T cell-mediated killing. In addition, we showed that co-ulture of primary CLL cells with CD20 CAR T cells results in selection of serpin B9-high CLL cells, suggesting these cells resist CAR T-cell killing.

CONCLUSIONS

Overall, the data indicate that serpin B9 is a resistance mediator for CAR T cell-mediated tumor cell killing that should be inhibited or bypassed to improve CAR T-cell responses.

Crosstalk between apoptosis and cytotoxic lymphocytes (CTLs) in the course of Lagovirus europaeus GI.1a infection in rabbits

Introduction

Lagovirus europaeus is a single-stranded RNA virus causing an acute fatal disease in wild and domestic rabbits around the world. Studies have shown that the pivotal process impacting the immune response against the disease is apoptosis, registered mainly in hepatocytes and in peripheral blood, together with an increased number of cytotoxic lymphocytes (CTLs). It is known that cytotoxic lymphocytes can induce target cells to undergo apoptosis on the pseudoreceptor pathway, such apoptosis having been found in several acute and chronic viral infections. The study aimed to assess the crosstalk between the apoptosis of peripheral blood lymphocytes and CD8+ T lymphocytes (as CTLs) in rabbits infected with 6 Lagovirus europaeus GI.1a viruses.

Material and Methods

Sixty rabbits of Polish hybrid breed comprising both sexes and weighing 3.2–4.2 kg were the experimental group, and an identical group was the control. Each of the six GI.1a Lagovirus europaeus viruses was inoculated into ten experimental rabbits. Control rabbits received glycerol as a placebo. Flow cytometric analysis was performed on blood from the study and control group animals for peripheral blood lymphocyte apoptosis and CTL percentage determination.

Results

The activation of apoptosis in peripheral blood lymphocytes was recorded from 4 h post inoculation (p.i.) up to 36 h p.i. The percentage of CTLs in the total blood pool decreased from 8 to 36 h p.i. A negative correlation between apoptosis of lymphocytes and the number of CTLs was proven.

Conclusion

This may be the first evidence of virus-induced CTL apoptosis in Lagovirus europaeus GI.1a infection.

Pore-Forming Proteins: From Pore Assembly to Structure by Quantitative Single-Molecule Imaging

Pore-forming proteins (PFPs) play a central role in many biological processes related to infection, immunity, cancer, and neurodegeneration. A common feature of PFPs is their ability to form pores that disrupt the membrane permeability barrier and ion homeostasis and generally induce cell death. Some PFPs are part of the genetically encoded machinery of eukaryotic cells that are activated against infection by pathogens or in physiological programs to carry out regulated cell death. PFPs organize into supramolecular transmembrane complexes that perforate membranes through a multistep process involving membrane insertion, protein oligomerization, and finally pore formation. However, the exact mechanism of pore formation varies from PFP to PFP, resulting in different pore structures with different functionalities. Here, we review recent insights into the molecular mechanisms by which PFPs permeabilize membranes and recent methodological advances in their characterization in artificial and cellular membranes. In particular, we focus on single-molecule imaging techniques as powerful tools to unravel the molecular mechanistic details of pore assembly that are often obscured by ensemble measurements, and to determine pore structure and functionality. Uncovering the mechanistic elements of pore formation is critical for understanding the physiological role of PFPs and developing therapeutic approaches.

Membrane damage and repair: a thin line between life and death

Bilayered membranes separate cells from their surroundings and form boundaries between intracellular organelles and the cytosol. Gated transport of solutes across membranes enables cells to establish vital ion gradients and a sophisticated metabolic network. However, an advanced compartmentalization of biochemical reactions makes cells also particularly vulnerable to membrane damage inflicted by pathogens, chemicals, inflammatory responses or mechanical stress. To avoid potentially lethal consequences of membrane injuries, cells continuously monitor the structural integrity of their membranes and readily activate appropriate pathways to plug, patch, engulf or shed the damaged membrane area. Here, we review recent insights into the cellular mechanisms that underly an effective maintenance of membrane integrity. We discuss how cells respond to membrane lesions caused by bacterial toxins and endogenous pore-forming proteins, with a primary focus on the intimate crosstalk between membrane proteins and lipids during wound formation, detection and elimination. We also discuss how a delicate balance between membrane damage and repair determines cell fate upon bacterial infection or activation of pro-inflammatory cell death pathways.

Granzyme B in Autoimmune Skin Disease

Autoimmune diseases often present with cutaneous symptoms that contribute to dysfunction, disfigurement, and in many cases, reduced quality-of-life. Unfortunately, treatment options for many autoimmune skin diseases are limited. Local and systemic corticosteroids remain the current standard-of-care but are associated with significant adverse effects. Hence, there is an unmet need for novel therapies that block molecular drivers of disease in a local and/or targeted manner. Granzyme B (GzmB) is a serine protease with known cytotoxic activity and emerging extracellular functions, including the cleavage of cell-cell junctions, basement membranes, cell receptors, and other structural proteins. While minimal to absent in healthy skin, GzmB is markedly elevated in alopecia areata, interface dermatitis, pemphigoid disease, psoriasis, systemic sclerosis, and vitiligo. This review will discuss the role of GzmB in immunity, blistering, apoptosis, and barrier dysfunction in the context of autoimmune skin disease. GzmB plays a causal role in the development of pemphigoid disease and carries diagnostic and prognostic significance in cutaneous lupus erythematosus, vitiligo, and alopecia areata. Taken together, these data support GzmB as a promising therapeutic target for autoimmune skin diseases impacted by impaired barrier function, inflammation, and/or blistering.

Effects of Aire on perforin expression in BMDCs via TLR7/8 and its therapeutic effect on type 1 diabetes

AIMS

Type 1 diabetes, as a kind of autoimmune diseases, usually results from the broken-down of self-tolerance. Autoimmune regulator (Aire), as a transcription factor, induces peripheral tolerance by regulating Toll-like receptor (TLR) expression in dendritic cells (DCs). Several studies have recently identified a small population of perforin-expressing DCs, which is an important population of tolerogenic DCs (tolDCs) that restricts autoreactive T cells in vivo through a perforin-mediated mechanism. Thus, the present study explored the specific relationship among Aire, perforin-expressing DCs and immune tolerance, as well as their roles in type 1 diabetes.

METHODS

We conducted studies based on the Aire-overexpressing bone marrow-derived dendritic cell (BMDC) model. And through in vitro and in vivo experiments to observe that Aire-overexpressing BMDCs which express perforin induce immune tolerance and treat type 1 diabetes via TLR7/8.

RESULTS

Aire enhances the expression of perforin in BMDCs after treatment with the TLR7/8 ligand as well as promotes the expression of TLR7/8 and myeloid differentiation primary response gene 88 (MyD88)-dependent pathway molecules. Aire-overexpressing BMDCs mediate apoptosis of allogeneic CD8⁺ T cells via perforin in vitro. Moreover, Aire-overexpressing BMDCs enhance the therapeutic effect of type 1 diabetes in non-obese diabetic (NOD) mice via perforin and induce apoptosis of autoreactive CD8⁺ T cells in vivo.

CONCLUSIONS

These results provide an experimental basis for comprehensively elucidating the role and significance of Aire expression in peripheral DCs, thereby providing new ideas for the treatment of autoimmune diseases by using Aire as a target to induce the production of perforin-expressing DCs.

In Vitro Expansion of Vδ1+ T Cells from Cord Blood by Using Artificial Antigen-Presenting Cells and Anti-CD3 Antibody

γδ T cells have the potential for adoptive immunotherapy since they respond to bacteria, viruses, and tumors. However, these cells represent a small fraction of the peripheral T-cell pool and require activation and proliferation for clinical benefits. In cord blood, there are some γδ T cells, which exhibit a naïve phenotype, and mostly include Vδ1+ T cells. In this study, we investigated the effect of CD3 signaling on cord blood γδ T-cell proliferation using K562-based artificial antigen presenting cells expressing costimulatory molecules. There were significantly more Vδ1+ T cells in the group stimulated with anti-CD3 antibody than in the group without. In cultured Vδ1+ T cells, DNAM-1 and NKG2D were highly expressed, but NKp30 and NKp44 showed low expression. Among various target cells, Vδ1+ T cells showed the highest cytotoxicity against U937 cells, but Daudi and Raji cells were not susceptible to Vδ1+ T cells. The major cytokines secreted by Vδ1+ T cells responding to U937 cells were Granzyme B, IFN-γ, and sFasL. Cytotoxicity by Vδ1+ T cells correlated with the expression level of PVR and Nectin of DNAM-1 ligands on the surface of target cells. Compared to Vδ2+ T cells in peripheral blood, cord blood Vδ1+ T cells showed varying cytotoxicity patterns depending on the target cells. Here, we determined the ideal conditions for culturing cord blood Vδ1+ T cells by observing that Vδ1+ T cells were more sensitive to CD3 signals than other subtypes of γδ T cells in cord blood. Cultured cord blood Vδ1+ T cells recognized target cells through activating receptors and secreted numerous cytotoxic cytokines. These results are useful for the development of tumor immunotherapy based on γδ T cells.

Complementing Testicular Immune Regulation: The Relationship between Sertoli Cells, Complement, and the Immune Response

Sertoli cells within the testis are instrumental in providing an environment for spermatogenesis and protecting the developing germ cells from detrimental immune responses which could affect fertility. Though these immune responses consist of many immune processes, this review focuses on the understudied complement system. Complement consists of 50+ proteins including regulatory proteins, immune receptors, and a cascade of proteolytic cleavages resulting in target cell destruction. In the testis, Sertoli cells protect the germ cells from autoimmune destruction by creating an immunoregulatory environment. Most studies on Sertoli cells and complement have been conducted in transplantation models, which are effective in studying immune regulation during robust rejection responses. In grafts, Sertoli cells survive activated complement, have decreased deposition of complement fragments, and express many complement inhibitors. Moreover, the grafts have delayed infiltration of immune cells and contain increased infiltration of immunosuppressive regulatory T cells as compared to rejecting grafts. Additionally, anti-sperm antibodies and lymphocyte infiltration have been detected in up to 50% and 30% of infertile testes, respectively. This review seeks to provide an updated overview of the complement system, describe its relationship with immune cells, and explain how Sertoli cells may regulate complement in immunoprotection. Identifying the mechanism Sertoli cells use to protect themselves and germ cells against complement and immune destruction is relevant for male reproduction, autoimmunity, and transplantation.

Rapamycin improves Graves' orbitopathy by suppressing CD4+ cytotoxic T lymphocytes

CD4+ cytotoxic T lymphocytes (CTLs) were recently implicated in immune-mediated inflammation and fibrosis progression of Graves' orbitopathy (GO). However, little is known about therapeutic targeting of CD4+ CTLs. Herein, we studied the effect of rapamycin, an approved mTOR complex 1 (mTORC1) inhibitor, in a GO mouse model, in vitro, and in patients with refractory GO. In the adenovirus-induced model, rapamycin significantly decreased the incidence of GO. This was accompanied by the reduction of both CD4+ CTLs and the reduction of orbital inflammation, adipogenesis, and fibrosis. CD4+ CTLs from patients with active GO showed upregulation of the mTOR pathway, while rapamycin decreased their proportions and cytotoxic function. Low-dose rapamycin treatment substantially improved diplopia and the clinical activity score in steroid-refractory patients with GO. Single-cell RNA-Seq revealed that eye motility improvement was closely related to suppression of inflammation and chemotaxis in CD4+ CTLs. In conclusion, rapamycin is a promising treatment for CD4+ CTL-mediated inflammation and fibrosis in GO.

Preclinical scenario of targeting myocardial fibrosis with chimeric antigen receptor (CAR) immunotherapy

Fibrosis is present in an important proportion of myocardial disorders. Injury activates cardiac fibroblasts, which deposit excess extracellular matrix, increasing tissue stiffness, impairing cardiac function, and leading to heart failure. Clinical therapies that directly target excessive fibrosis are limited, and more effective treatments are needed. Immunotherapy based on chimeric antigen receptor (CAR) T cells is a novel technique that redirects T lymphocytes toward specific antigens to eliminate the target cells. It is currently used in haematological cancers but has demonstrated efficacy in mouse models of hypertensive cardiac fibrosis, with activated fibroblasts as the target cells. CAR T cell therapy is associated with significant toxicities, but CAR natural killer cells can overcome efficacy and safety limitations. The use of CAR immunotherapy offers a potential alternative to current therapies for fibrosis reduction and restoration of cardiac function in patients with myocardial fibrosis.

Necroptosis-dependent Immunogenicity of Cisplatin: Implications for Enhancing the Radiation-induced Abscopal Effect

PURPOSE

Cisplatin is increasingly used in chemoimmunotherapy and may enhance the T cell-dependent radiation-induced abscopal effect, but how it promotes antitumor immunity is poorly understood. We investigated whether and why cisplatin is immunogenic, and the implications for the cisplatin-enhanced abscopal effect.

EXPERIMENTAL DESIGN

Cisplatin, carboplatin, and the well-known immunogenic cell death (ICD) inducer oxaliplatin were compared for their potency to enhance the abscopal effect and induce type I IFN (IFN-I) and extracellular ATP, danger signals of ICD. The hypothetical role of necroptosis and associated damage-associated molecular patterns for cisplatin-induced ICD was investigated by inhibitors and knockout cells in vitro and in two tumor models in mice. A novel necroptosis signature for tumor immune cell infiltration and therapy response was developed.

RESULTS

Cisplatin enhanced the abscopal effect more strongly than oxaliplatin or carboplatin. This correlated with higher induction of IFN-I and extracellular ATP by cisplatin, in a necroptosis-dependent manner. Cisplatin triggered receptor-interacting protein kinase 3 (RIPK3)-dependent tumor cell necroptosis causing cytosolic mitochondrial DNA (mtDNA) release, initiating the cyclic GMP-AMP synthase-stimulator of interferon genes pathway and IFN-I secretion promoting T-cell cross-priming by dendritic cells (DC). Accordingly, tumor cell RIPK3 or mtDNA deficiency and loss of IFN-I or ATP signaling diminished the cisplatin-enhanced abscopal effect. Cisplatin-treated tumor cells were immunogenic in vaccination experiments, depending on RIPK3 and mtDNA. In human tumor transcriptome analysis, necroptotic features correlated with abundant CD8+ T cells/DCs, sparse immunosuppressive cells, and immunotherapy response.

CONCLUSIONS

Cisplatin induces antitumor immunity through necroptosis-mediated ICD. Our findings may help explain the benefits of cisplatin in chemo(radio)immunotherapies and develop clinical trials to investigate whether cisplatin enhances the abscopal effect in patients.

Roles of natural killer cells in immunity to cancer, and applications to immunotherapy

Great strides have been made in recent years towards understanding the roles of natural killer (NK) cells in immunity to tumours and viruses. NK cells are cytotoxic innate lymphoid cells that produce inflammatory cytokines and chemokines. By lysing transformed or infected cells, they limit tumour growth and viral infections. Whereas T cells recognize peptides presented by MHC molecules, NK cells display receptors that recognize stress-induced autologous proteins on cancer cells. At the same time, their functional activity is inhibited by MHC molecules displayed on such cells. The enormous potential of NK cells for immunotherapy for cancer is illustrated by their broad recognition of stressed cells regardless of neoantigen presentation, and enhanced activity against tumours that have lost expression of MHC class I owing to acquired resistance mechanisms. As a result, many efforts are under way to mobilize endogenous NK cells with therapeutics, or to provide populations of ex vivo-expanded NK cells as a cellular therapy, in some cases by equipping the NK cells with chimeric antigen receptors. Here we consider the key features that underlie why NK cells are emerging as important new additions to the cancer therapeutic arsenal.

Baseline red blood cell distribution width and perforin, dynamic levels of interleukin 6 and lactate are predictors of mortality in patients with sepsis

BACKGROUND

Sepsis is a critical illness often encountered in the intensive care unit. However, prognostic biomarkers for sepsis have limited sensitivity. This study aimed to identify more sensitive predictors of mortality through repeated monitoring of laboratory parameters.

METHODS

Patients with sepsis (Sepsis 3.0 criteria met) were recruited and divided into the survivor and nonsurvivor groups after 28 days. Data on blood biochemistry, lymphocyte subsets, and cytokines were obtained on the first and seventh hospitalization days. Univariate and multivariate Cox regression analyses were performed to explore the correlation between these variables and patient mortality.

RESULTS

Forty patients with sepsis were included. The mortality rate was 37.5%. Red blood cell distribution width-standard deviation (RDWSD) (hazard ratio [HR] = 1.107 [95% CI: 1.005-1.219], p = 0.040) and perforin level (HR = 1.001 [95% CI: 1-1.003], p = 0.035) on the first day, as well as lactate (HR = 112.064 [95% CI: 2.192-5729.629], p = 0.019) and interleukin 6 (IL-6) (HR = 1.005 [95% CI: 1.001-1.008], p = 0.014) levels on the seventh day, were independent risk factors of mortality. If the patients were divided into two groups based on RDWSD (normal: n = 31; increased: n = 9), the Kaplan-Meier curves showed that the group with increased RDWSD had a lower survival (p = 0.025).

CONCLUSION

Baseline RDWSD and perforin, along with dynamic IL-6 and lactate levels, were independent predictors of mortality in patients with sepsis.

Innate lymphoid cells: potential targets for cancer therapeutics

Innate lymphoid cells (ILCs) comprise a number of different subsets, including natural killer (NK) cells, ILC1s, ILC2s, ILC3s, and lymphoid tissue-inducer (LTi) cells that express receptors and signaling pathways that are highly responsive to continuously changing microenvironmental cues. In this Review, we highlight the key features of innate cells that define their capacity to respond rapidly to different environments, how this ability can drive both tumor protection (limiting tumor development) or, alternatively, tumor progression, promoting tumor dissemination and resistance to immunotherapy. We discuss how understanding the regulation of ILCs that can detect tumor cells early in a response opens the possibility of exploiting this functional plasticity to develop rational therapeutic strategies to bolster adaptive immune responses and improve patient outcomes.

Antitumor Immunity Exerted by Natural Killer and Natural Killer T Cells in the Liver

The liver plays crucial roles in systemic immunity and greatly contributes to the systemic defense mechanism. Antitumor immunity in the liver is especially critical for the defense against systemic tumor cell dissemination. To achieve effective defense against metastatic tumor cells, liver immune cells with powerful cytotoxic activities construct a potent defense mechanism. In the liver, as compared with other organs, there is a significantly more intense percentage of innate immune lymphocytes, such as natural killer (NK) and NKT cells. These characteristic lymphocytes survey the portal blood transferred to the liver from the alimentary tract and eliminate malignant cells with their robust cytotoxic ability. Additionally, with their active cytokine-producing capacity, these innate lymphocytes initiate immunological sequences by adaptive immune cells. Therefore, they are crucial contributors to systemic antitumor immunity. These attractive immune cells help conduct a fundamental investigation of tumor immunity and act as a target of clinical measures for cancer therapies. This review discusses the mechanisms of these innate lymphocytes regarding recognition and cytotoxicity against tumor cells and the possibility of clinical applications for therapeutic measures.

Manipulating NK cellular therapy from cancer to invasive fungal infection: promises and challenges

The ideal strategy to fight an infection involves both (i) weakening the invading pathogen through conventional antimicrobial therapy, and (ii) strengthening defense through the augmentation of host immunity. This is even more pertinent in the context of invasive fungal infections whereby the majority of patients have altered immunity and are unable to mount an appropriate host response against the pathogen. Natural killer (NK) cells fit the requirement of an efficient, innate executioner of both tumour cells and pathogens – their unique, targeted cell killing mechanism, combined with other arms of the immune system, make them potent effectors. These characteristics, together with their ready availability (given the various sources of extrinsic NK cells available for harvesting), make NK cells an attractive choice as adoptive cellular therapy against fungi in invasive infections. Improved techniques in ex vivo NK cell activation with expansion, and more importantly, recent advances in genetic engineering including state-of-the-art chimeric antigen receptor platform development, have presented an opportune moment to harness this novel therapeutic as a key component of a multipronged strategy against invasive fungal infections.

Dendritic cells and natural killer cells: The road to a successful oncolytic virotherapy

Every type of cancer tissue is theoretically more vulnerable to viral infection. This natural proclivity has been harnessed as a new anti-cancer therapy by employing oncolytic viruses (OVs) to selectively infect and destroy cancer cells while providing little or no harm with no toxicity to the host. Whereas the primary oncolytic capabilities of OVs initially sparked the greatest concern, the predominant focus of research is on the association between OVs and the host immune system. Numerous OVs are potent causal agents of class I MHC pathway-related chemicals, enabling early tumor/viral immune recognition and cytokine-mediated response. The modified OVs have been studied for their ability to bind to dendritic cells (DCs) by expressing growth factors, chemokines, cytokines, and defensins inside the viral genome. OVs, like reovirus, can directly infect DCs, causing them to release chemokines and cytokines that attract and excite natural killer (NK) cells. In addition, OVs can directly alter cancer cells' sensitivity to NK by altering the expression levels of NK cell activators and inhibitors on cancerous cells. Therefore, NK cells and DCs in modulating the therapeutic response should be considered when developing and improving future OV-based therapeutics, whether modified to express transgenes or used in combination with other drugs/immunotherapies. Concerning the close relationship between NK cells and DCs in the potential of OVs to kill tumor cells, we explore how DCs and NK cells in tumor microenvironment affect oncolytic virotherapy and summarize additional information about the interaction mentioned above in detail in this work.

Delayed Drug Hypersensitivity Reactions: Molecular Recognition, Genetic Susceptibility, and Immune Mediators

Drug hypersensitivity reactions are classified into immediate and delayed types, according to the onset time. In contrast to the immediate type, delayed drug hypersensitivity mainly involves T lymphocyte recognition of the drug antigens and cell activation. The clinical presentations of such hypersensitivity are various and range from mild reactions (e.g., maculopapular exanthema (MPE) and fixed drug eruption (FDE)), to drug-induced liver injury (DILI) and severe cutaneous adverse reactions (SCARs) (e.g., Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP)). The common culprits of delayed drug hypersensitivity include anti-epileptics, antibiotics, anti-gout agents, anti-viral drugs, etc. Delayed drug hypersensitivity is proposed to be initiated by different models of molecular recognition, composed of drug/metabolite antigen and endogenous peptide, HLA presentation, and T cell receptor (TCR) interaction. Increasing the genetic variants of HLA loci and drug metabolic enzymes has been identified to be responsible for delayed drug hypersensitivity. Furthermore, preferential TCR clonotypes, and the activation of cytotoxic proteins/cytokines/chemokines, are also involved in the pathogenesis of delayed drug hypersensitivity. This review provides a summary of the current understanding of the molecular recognition, genetic susceptibility, and immune mediators of delayed drug hypersensitivity.

The Therapeutic Potential of Pyroptosis in Melanoma

Pyroptosis is a programmed cell death characterized by the rupture of the plasma membranes and release of cellular content leading to inflammatory reaction. Four cellular mechanisms inducing pyroptosis have been reported thus far, including the (i) caspase 1-mediated canonical, (ii) caspase 4/5/11-mediated non-canonical, (iii) caspase 3/8-mediated and (iv) caspase-independent pathways. Although discovered as a defense mechanism protecting cells from infections of intracellular pathogens, pyroptosis plays roles in tumor initiation, progression and metastasis of tumors, as well as in treatment response to antitumor drugs and, consequently, patient outcome. Pyroptosis induction following antitumor therapies has been reported in several tumor types, including lung, colorectal and gastric cancer, hepatocellular carcinoma and melanoma. This review provides an overview of the cellular pathways of pyroptosis and discusses the therapeutic potential of pyroptosis induction in cancer, particularly in melanoma.

NK- and T-cell granzyme B and K expression correlates with age, CMV infection and influenza vaccine-induced antibody titres in older adults

Granzymes are a family of serine-proteases that act as critical mediators in the cytolytic and immunomodulatory activities of immune cells such as CD8⁺ T-cells and natural killer (NK) cells. Previous work indicates that both granzyme B (GZB) and K (GZK) are increased with age in CD8⁺ T-cells, and in the case of GZB, contribute to dysfunctional immune processes observed in older adults. Here, we sought to determine how GZB and GZK expression in NK-cells, and CD4⁺, CD8⁺, and gamma-delta T-cells, quantified in terms of positive cell frequency and mean fluorescence intensity (MFI), differed with age, age-related health-traits and the antibody response to high-dose influenza vaccine. We found that the frequency and MFI of GZB-expressing NK-cells, and CD8⁺ and Vδ1+ T-cells, and GZK-expressing CD8⁺ T-cells was significantly higher in older (66-97 years old; n = 75) vs. younger (24-37 years old; n = 10) adults by up to 5-fold. There were no significant associations of GZB/GZK expression with sex, frailty or plasma levels of TNF or IL-6 in older adults, but those who were seropositive for cytomegalovirus (CMV) exhibited significantly higher frequencies of GZB+ NK-cells, and CD4⁺, CD8⁺ and Vδ1+ T-cells, and GZK+ CD8⁺ T-cells (Cohen's d = .5-1.5). Pre-vaccination frequencies of GZB+ NK-cells were positively correlated with vaccine antibody responses against A/H3N2 (d = .17), while the frequencies of GZK+ NK and CD8⁺ T-cells were inversely associated with A/H1N1 (d = -0.18 to -0.20). Interestingly, GZK+ NK-cell frequency was inversely correlated with pre-vaccination A/H1N1 antibody titres, as well as those measured over the previous 4 years, further supporting a role for this subset in influencing vaccine antibody-responses. These findings further our understanding of how granzyme expression in different lymphoid cell-types may change with age, while suggesting that they influence vaccine responsiveness in older adults.

A common genetic variation in GZMB may associate with cancer risk in patients with Lynch syndrome

Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is a common genetic predisposition to cancer due to germline mutations in genes affecting DNA mismatch repair. Due to mismatch repair deficiency, developing tumors are characterized by microsatellite instability (MSI-H), high frequency of expressed neoantigens and good clinical response to immune checkpoint inhibitors. Granzyme B (GrB) is the most abundant serine protease in the granules of cytotoxic T-cells and natural killer cells, mediating anti-tumor immunity. However, recent results confirm a diverse range of physiological functions of GrB including that in extracellular matrix remodelling, inflammation and fibrosis. In the present study, our aim was to investigate whether a frequent genetic variation of GZMB, the gene encoding GrB, constituted by three missense single nucleotide polymorphisms (rs2236338, rs11539752 and rs8192917) has any association with cancer risk in individuals with LS. In silico analysis and genotype calls from whole exome sequencing data in the Hungarian population confirmed that these SNPs are closely linked. Genotyping results of rs8192917 on a cohort of 145 individuals with LS demonstrated an association of the CC genotype with lower cancer risk. In silico prediction proposed likely GrB cleavage sites in a high proportion of shared neontigens in MSI-H tumors. Our results propose the CC genotype of rs8192917 as a potential disease-modifying genetic factor in LS.

Cadmium impairs the development of natural killer cells and bidirectionally modifies their capacity for cytotoxicity

Cadmium (Cd) is a highly toxic heavy metal in the environment. The aim of this study was to investigate the impact of Cd on natural killer (NK) cells. C57BL/6 mice were treated with 10 ppm Cd via drinking water for 3 months, and the development of NK cells in the bone marrow (BM) and the cytotoxicity of mature NK (mNK) cells in the peripheral immune organs were evaluated thereafter; the impact of Cd on the cytotoxicity of mNK cells from human peripheral blood mononuclear cells (PBMC) was also investigated. Whereas Cd treatment impaired the differentiation of NK progenitors in the BM, Cd treatment activated the JAK3/STAT5 signaling to drive the proliferation of mNK cells and thereby lead to a compensation increase of mNK cells in the peripheral immune organs of mice. Additionally, Cd treatment bidirectionally regulated the cytotoxicity of mouse mNK cells to differential tumor cells, dependent on the levels of Fas expression in the tumor cells; mechanically, Cd treatment activated the JAK3/STAT5 signaling to promote the expression of FasL in mNK cells to increase their cytotoxicity, while Cd treatment reduced the expression of granzyme B in mNK cells to impair their cytotoxicity in the peripheral immune organs of mice. Likewise, in vitro assays indicated that Cd treatment also activated the JAK3/STAT5 signaling to increase the expression of FasL, whereas Cd treatment reduced the expression of granzyme B in human mNK cells. Thus Cd treatment impaired the development of NK cells in the BM and bidirectionally regulated the cytotoxicity of mNK cells in the peripheral immune organs, which may extend our current understanding for the immunotoxicity of Cd.

Overexpressed perforin contributes to the melanocyte destruction via epigenetic regulation in patients with vitiligo

BACKGROUND

Perforin (PRF), a pivotal cytotoxic effector molecule of activated CD8⁺ T cells, has a crucial role in the pathogenesis of vitiligo. However, the mechanisms leading to the abnormal perforin expression remain poorly understood in the CD8⁺ T cells of vitiligo patients.

OBJECTIVE

To investigate the contributions of DNA methylation to the abnormal expression of perforin in CD8⁺ T cells of vitiligo patients.

METHODS

Skin samples and CD8⁺ T cells from peripheral blood were collected to detect the expression levels of perforin in vitiligo patients. The methylation status of the perforin promoter was investigated by bisulfite sequencing. The apoptosis of melanocytes co-cultured with CD8⁺ T cells was evaluated to determinate the cytotoxic role of perforin.

RESULTS

Increased CD8⁺ and perforin⁺ cells were found in lesion of vitiligo patients. The expression levels of perforin were elevated in the CD8⁺ T cells from peripheral blood of vitiligo patients and their culture supernatants. The perforin promoter was hypomethylated in vitiligo CD8⁺ T cells. Treatment of normal CD8⁺ T cells with the DNA methylation inhibitor 5-Azacytidine (5-Azac) reduced the perforin methylation level and caused perforin overexpression. The methylation levels of perforin were inversely correlated with its mRNA expression in CD8⁺ T cells. The apoptosis rates of the melanocytes co-cultured with vitiligo- and 5-Azac-treated-normal CD8⁺ T cells were significantly increased compared with normal-untreated CD8⁺ T cells. And the apoptosis rates of melanocytes co-cultured with si-PRF-treated-vitiligo CD8⁺ T cells were significantly decreased compared with vitiligo-untreated CD8⁺ T cells.

CONCLUSION

Hypomethylation of the perforin promoter contributes to its overexpression in CD8⁺ T cells from vitiligo patients, which then mediates the melanocyte destruction in vitiligo.

T lymphocyte characteristics and immune repertoires in the epicardial adipose tissue of heart failure patients

Background

Epicardial adipose tissue (EAT) acts as an active immune organ and plays a critical role in the pathogenesis of heart failure (HF). However, the characteristics of immune cells in EAT of HF patients have rarely been elucidated.

Methods

To identify key immune cells in EAT, an integrated bioinformatics analysis was performed on public datasets. EAT samples with paired subcutaneous adipose tissue (SAT), heart, and peripheral blood samples from HF patients were collected in validation experiments. T cell receptor (TCR) repertoire was assessed by high-throughput sequencing. The phenotypic characteristics and key effector molecules of T lymphocytes in EAT were assessed by flow cytometry and histological staining.

Results

Compared with SAT, EAT was enriched for immune activation-related genes and T lymphocytes. Compared with EAT from the controls, activation of T lymphocytes was more pronounced in EAT from HF patients. T lymphocytes in EAT of HF patients were enriched by highly expanded clonotypes and had greater TCR clonotype sharing with cardiac tissue relative to SAT. Experiments confirmed the abundance of IFN-γ⁺ effector memory T lymphocytes (T_EM) in EAT of HF patients. CCL5 and GZMK were confirmed to be associated with T lymphocytes in EAT of HF patients.

Conclusion

EAT of HF patients was characterized by pronounced immune activation of clonally expanded IFN-γ⁺ T_EM and a generally higher degree of TCR clonotypes sharing with paired cardiac tissue.

Chemotherapeutics and CAR-T Cell-Based Immunotherapeutics Screening on a 3D Bioprinted Vascularized Breast Tumor Model

Despite substantial advancements in development of cancer treatments, lack of standardized and physiologically-relevant in vitro testing platforms limit the early screening of anticancer agents. A major barrier is the complex interplay between the tumor microenvironment and immune response. To tackle this, a dynamic-flow based 3D bioprinted multi-scale vascularized breast tumor model, responding to chemo and immunotherapeutics is developed. Heterotypic tumors are precisely bioprinted at pre-defined distances from a perfused vasculature, exhibit tumor angiogenesis and cancer cell invasion into the perfused vasculature. Bioprinted tumors treated with varying dosages of doxorubicin for 72 h portray a dose-dependent drug response behavior. More importantly, a cell based immune therapy approach is explored by perfusing HER2-targeting chimeric antigen receptor (CAR) modified CD8+ T cells for 24 or 72 h. Extensive CAR-T cell recruitment to the endothelium, substantial T cell activation and infiltration to the tumor site, resulted in up to ≈70% reduction in tumor volumes. The presented platform paves the way for a robust, precisely fabricated, and physiologically-relevant tumor model for future translation of anti-cancer therapies to personalized medicine.

IL-33 induces granzyme C expression in murine mast cells via an MSK1/2-CREB-dependent pathway

Granzymes comprise a group of proteases involved in the killing of infected or cancerous cells by the immune system. Although best studied in T cells and natural killer (NK) cells, they are also expressed in some innate immune cells. Granzymes B and C are encoded in the mouse chymase locus that also encodes a number of mast cell-specific proteases. In line with this, mast cells can express granzyme B, although how this is regulated and their ability to express other granzymes is less well studied. We therefore examined how IL-33, a cytokine able to activate mast cells but not induce degranulation, regulated granzyme B and C levels in mast cells. Granzyme C, but not B, mRNA was strongly up-regulated in bone marrow-derived mast cells following IL-33 stimulation and there was a corresponding increase in granzyme C protein. These increases in both granzyme C mRNA and protein were blocked by a combination of the p38α/β MAPK inhibitor VX745 and the MEK1/2 inhibitor PD184352, which blocks the activation of ERK1/2. ERK1/2 and p38α activate the downstream kinases, mitogen and stress-activated kinases (MSK) 1 and 2, and IL-33 stimulated the phosphorylation of MSK1 and its substrate CREB in an ERK1/2 and p38-dependent manner. The promoter for granzyme C contains a potential CREB-binding site. Bone marrow-derived mast cells from either MSK1/2 double knockout or CREB Ser133Ala knockin mice were unable to up-regulate granzyme C. Together these results indicate that IL-33-induced granzyme C expression in mast cells is regulated by an MSK1/2-CREB-dependent pathway.

Pore-forming proteins as drivers of membrane permeabilization in cell death pathways

Regulated cell death (RCD) relies on activation and recruitment of pore-forming proteins (PFPs) that function as executioners of specific cell death pathways: apoptosis regulator BAX (BAX), BCL-2 homologous antagonist/killer (BAK) and BCL-2-related ovarian killer protein (BOK) for apoptosis, gasdermins (GSDMs) for pyroptosis and mixed lineage kinase domain-like protein (MLKL) for necroptosis. Inactive precursors of PFPs are converted into pore-forming entities through activation, membrane recruitment, membrane insertion and oligomerization. These mechanisms involve protein-protein and protein-lipid interactions, proteolytic processing and phosphorylation. In this Review, we discuss the structural rearrangements incurred by RCD-related PFPs and describe the mechanisms that manifest conversion from autoinhibited to membrane-embedded molecular states. We further discuss the formation and maturation of membrane pores formed by BAX/BAK/BOK, GSDMs and MLKL, leading to diverse pore architectures. Lastly, we highlight commonalities and differences of PFP mechanisms involving BAX/BAK/BOK, GSDMs and MLKL and conclude with a discussion on how, in a population of challenged cells, the coexistence of cell death modalities may have profound physiological and pathophysiological implications.

Behavioral factors to modulate immunotherapy efficacy in cancer

Immune checkpoint inhibitors, including anti-PD-1 and anti-CTLA-4 therapies, are used to (re)activate the immune system to treat cancer. Despite promising results, a large group of patients does not respond to checkpoint inhibition. In the vulnerability-stress model of behavioral medicine, behavioral factors, such as stress, exercise and classical pharmacological conditioning, predict cancer incidence, recurrence and the efficacy of conventional cancer treatments. Given the important role of the immune system in these processes, certain behavior may be promising to complement immune checkpoint inhibition therapy. Here, we discuss the preliminary evidence and suitability of three behavioral mechanisms, i.e. stress modulation, exercise and classical pharmacological conditioning for the benefit of immunotherapy. It is crucial to study the potential beneficial effects of behavioral strategies that support immunotherapeutic anti-tumor effects with rigorous experimental evidence, to exploit behavioral mechanisms in improving checkpoint inhibition efficacy.

Basophils from allergy to cancer

Human basophils, first identified over 140 years ago, account for just 0.5-1% of circulating leukocytes. While this scarcity long hampered basophil studies, innovations during the past 30 years, beginning with their isolation and more recently in the development of mouse models, have markedly advanced our understanding of these cells. Although dissimilarities between human and mouse basophils persist, the overall findings highlight the growing importance of these cells in health and disease. Indeed, studies continue to support basophils as key participants in IgE-mediated reactions, where they infiltrate inflammatory lesions, release pro-inflammatory mediators (histamine, leukotriene C₄: LTC₄) and regulatory cytokines (IL-4, IL-13) central to the pathogenesis of allergic diseases. Studies now report basophils infiltrating various human cancers where they play diverse roles, either promoting or hampering tumorigenesis. Likewise, this activity bears remarkable similarity to the mounting evidence that basophils facilitate wound healing. In fact, both activities appear linked to the capacity of basophils to secrete IL-4/IL-13, with these cytokines polarizing macrophages toward the M2 phenotype. Basophils also secrete several angiogenic factors (vascular endothelial growth factor: VEGF-A, amphiregulin) consistent with these activities. In this review, we feature these newfound properties with the goal of unraveling the increasing importance of basophils in these diverse pathobiological processes.

The Association of CD8+ Cytotoxic T Cells and Granzyme B+ Lymphocytes with Immunosuppressive Factors, Tumor Stage and Prognosis in Cutaneous Melanoma

The immunosuppressive tumor microenvironment (TME) consists of suppressive cells producing a variety of immunomodulatory proteins, such as programmed death ligand 1 (PD-L1) and indoleamine-2,3-dioxygenase (IDO). Although granzyme B (GrB) is known to convey the cytolytic activities of CD8+ cytotoxic lymphocytes, it is also expressed by other cells, such as regulatory T and B cells, for immunosuppressive purposes. The role of GrB+ lymphocytes in melanoma has not been examined extensively. In this study, benign, premalignant, and malignant melanocytic tumors were stained immunohistochemically for CD8 and GrB. PD-L1 was also stained from malignant samples that had accompanying clinicopathological data. The association of CD8+ and GrB+ lymphocytes with PD-L1 expression, tumor stage, prognosis, and previously analyzed immunosuppressive factors were evaluated. Our aim was to obtain a more comprehensive perception of the immunosuppressive TME in melanoma. The results show that both CD8+ and GrB+ lymphocytes were more abundant in pT4 compared to pT1 melanomas, and in lymph node metastases compared to primary melanomas. Surprisingly, a low GrB/CD8 ratio was associated with better recurrence-free survival in primary melanomas, which indicates that GrB+ lymphocytes might represent activated immunosuppressive lymphocytes rather than cytotoxic T cells. In the present study, CD8+ lymphocytes associated positively with both tumor and stromal immune cell PD-L1 and IDO expression. In addition, PD-L1+ tumor and stromal immune cells associated positively with IDO+ stromal immune and melanoma cells. The data suggest that IDO and PD-L1 seem to be key immunosuppressive factors in CD8+ lymphocyte-predominant tumors in CM.

A more novel and robust gene signature predicts outcome in patients with esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a life-threatening thoracic tumor with a poor prognosis. The tumor microenvironment (TME) mainly comprises tumor cells and tumor-infiltrating immune cells mixed with stromal components. The latest research has displayed that tumor immune cell infiltration (ICI) is closely connected with the ESCC patients' clinical prognosis. This study was designed to construct a gene signature based on the ICI of ESCC to predict prognosis.

METHODS

Based on the selection criteria we set, the eligible ESCC cases from the GSE53625 and TCGA-ESCA datasets were chosen for the training cohort and the validation cohort, respectively. Unsupervised clustering detailed grouped ESCC cases of the training cohort based on the ICI profile. We determined the differential expression genes (DEGs) between the ICI clusters, and, subsequently, we adopted the univariate Cox analysis to recognize DEGs with prognostic potential. These screened DEGs underwent a Lasso regression, which then generated a gene signature. The harvested signature's predictive ability was further examined by the Kaplan-Meier analysis, Cox analysis, ROC, IAUC, and IBS. More importantly, we listed similar studies in the most recent year and compared theirs with ours. We performed the functional annotation, immune relevant signature correlation analysis, and immune infiltrating analysis to thoroughly understand the functional mechanism of the signature and the immune cells' roles in the gene signature's predicting capacity.

RESULTS

A sixteen-gene signature (ARSD, BCAT1, BIK, CLDN11, DLEU7-AS1, GGH, IGFBP2, LINC01037, LINC01446, LINC01497, M1AP, PCSK2, PCSK5, PPP2R2A, TIGD7, and TMSB4X) was generated from the Lasso model. We then confirmed the signature as having solid and stable prognostic capacity by several statistical methods. We revealed the superiority of our signature after comparing it to our predecessors, and the GSEA uncovered the specifically mechanism of action related to the gene signature. Two immune relevant signatures, including GZMA and LAG3 were identified associating with our signature. The immune-infiltrating analysis identified crucial roles of resting mast cells, which potentially support the sixteen-gene signature's prognosis ability.

CONCLUSIONS

We discovered a robust sixteen-gene signature that can accurately predict ESCC prognosis. The immune relevant signatures, GZMA and LAG3, and resting mast cells infiltrating were closely linked to the sixteen-gene signature's ability.

Paradoxical roles for programmed cell death signaling during viral infection of the central nervous system

Programmed cell death (PCD) is an essential mechanism of antimicrobial defense. Recent work has revealed an unexpected diversity in the types of PCD elicited during infection, as well as defined unique roles for different PCD modalities in shaping the immune response. Here, we review recent work describing unique ways in which PCD signaling operates within the infected central nervous system (CNS). These studies reveal striking complexity in the regulation of PCD signaling by CNS cells, including both protective and pathological outcomes in the control of infection. Studies defining the specialized molecular mechanisms shaping PCD responses in the CNS promise to yield much needed new insights into the pathogenesis of neuroinvasive viral infection, informing future therapeutic development.

Pyroptosis in inflammatory bone diseases: Molecular insights and targeting strategies

Inflammatory bone diseases include osteoarthritis (OA) and rheumatoid arthritis (RA), which can cause severe bone damage in a chronic inflammation state, putting tremendous pressure on the patients' families and government agencies regarding medical costs. In addition, the complexity of osteoimmunology makes research on these diseases difficult. Hence, it is urgent to determine the potential mechanisms and find effective drugs to target inflammatory bone diseases to reduce the negative effects of these diseases. Recently, pyroptosis, a gasdermin-induced necrotic cell death featuring secretion of pro-inflammatory cytokines and lysis, has become widely known. Based on the effect of pyroptosis on immunity, this process has gradually emerged as a vital component in the etiopathogenesis of inflammatory bone diseases. Herein, we review the characteristics and mechanisms of pyroptosis and then focus on its clinical significance in inflammatory bone diseases. In addition, we summarize the current research progress of drugs targeting pyroptosis to enhance the therapeutic efficacy of inflammatory bone diseases and provide new insights for future directions.

Beyond target cell death - Granzyme serine proteases in health and disease

Granzymes are a family of small (∼32 kDa) serine proteases with a range of substrate specificities that are stored in, and released from, the cytoplasmic secretory vesicles ('granules') of cytotoxic T lymphocytes and natural killer cells. Granzymes are not digestive proteases but finely tuned processing enzymes that target their substrates in specific ways to activate various signalling pathways, or to inactivate viral proteins and other targets. Great emphasis has been placed on studying the pro-apoptotic functions of granzymes, which largely depend on their synergy with the pore-forming protein perforin, on which they rely for penetration into the target cell cytosol to access their substrates. While a critical role for granzyme B in target cell apoptosis is undisputed, both it and the remaining granzymes also influence a variety of other biological processes (including important immunoregulatory functions), which are discussed in this review. This includes the targeting of many extracellular as well as intracellular substrates, and can also lead to deleterious outcomes for the host if granzyme expression or function are dysregulated or abrogated. A final important consideration is that granzyme repertoire, biochemistry and function vary considerably across species, probably resulting from the pressures applied by viruses and other pathogens across evolutionary time. This has implications for the interpretation of granzyme function in preclinical models of disease.

Biosynthetic neoantigen displayed on bacteria derived vesicles elicit systemic antitumour immunity

Neoantigens derived from mutant proteins in tumour cells could elicit potent personalized anti-tumour immunity. Nevertheless, the layout of vaccine vehicle and synthesis of neoantigen are pivotal for stimulating robust response. The power of synthetic biology enables genetic programming bacteria to produce therapeutic agents under contol of the gene circuits. Herein, we genetically engineered bacteria to synthesize fusion neoantigens, and prepared bacteria derived vesicles (BDVs) presenting the neoantigens (BDVs-Neo) as personalized therapeutic vaccine to drive systemic antitumour response. BDVs-Neo and granulocyte-macrophage colony-stimulating factor (GM-CSF) were inoculated subcutaneously within hydrogel (Gel), whereas sustaining release of BDVs-Lipopolysaccharide (LPS) and GM-CSF recruited the dendritic cells (DCs). Virtually, Gel-BDVs-Neo combined with the programmed cell death protein 1 (PD-1) antibody intensively enhanced proliferation and activation of tumour-infiltrated T cells, as well as memory T cell clone expansion. Consequently, BDVs-Neo combining with checkpoint blockade therapy effectively prevented tumour relapse and metastasis.

Supramolecular Coassembled Peptide Hydrogels for Efficient Anticancer Therapy by RNS-Based PDT and Immune Microenvironment Regulation

Photodynamic therapy (PDT) has attracted much attention in cancer treatment due to its tumor selectivity and noninvasive nature. Recent studies have demonstrated that PDT mediated reactive oxygen species (ROS) generation in tumor microenvironment (TME) synergistically improves the efficacy of immune checkpoint blockade (ICB) therapy. However, the instability and short half-life of the ROS generated by PDT limit its clinical applications. Herein, a coassembled peptide hydrogel comprising two short peptides that contained the same assembly unit, Ce6-KKFKFEFEF (KEF-Ce6) and RRRRRRRR-KFKFEFEF (KEF-R8) is developed. When exposed to 635 nm laser irradiation, KEF-Ce6 released ROS, while KEF-R8 plays as nitric oxide (NO) donor. Subsequently, ROS reacts with NO to produce reactive nitrogen species (RNS). Both in vitro and in vivo experiments prove that converting ROS into more cytotoxic RNS caused intense cell death. Importantly, it is observed that tumor-associated macrophages (TAMs) are polarized to proinflammatory types (M1-type) by the RNS-based PDT. The increase of M1 macrophages relieves the immunosuppressive situation in TME. Thus, when combined with αPD-L1 treatment, the survival time of tumor-bearing mice is prolonged. Overall, a simple yet efficient coassembled hydrogel that can cascade release ROS/NO/RNS and strengthen antitumor T cell responses to boost cancer immunotherapy by reprogramming TAMs is provided.

Pathology of drug hypersensitivity reactions and mechanisms of immune tolerance

Immune-mediated type IV adverse drug reactions are idiosyncratic in nature, generally not related to the primary or secondary pharmacology of the drug. Due to their complex nature and rarity, these iatrogenic reactions are seldom predicted or encountered during preclinical/early clinical development stages, and often precipitate upon exposure to wider populations (i.e. phase III onwards). They confer a burden on the healthcare sector in both a clinical and financial sense presenting a severe impediment to the drug discovery and development process. Research over the past 50 years has improved our understanding of these reactions markedly as both in vitro and in vivo studies have placed the role of the immune system, in particular; drug-responsive T cells, firmly in the spotlight as the mediators of these reactions. Indeed, the role of different populations of T cells in adverse events and the interaction of drug molecules with HLA proteins expressed on the surface of antigen-presenting cells is of considerable interest. Herein, this review examines the pathways of immune-mediated adverse events including the various T cell subtypes implicated and the mechanisms of T cell activation. Additionally, we address the enigma of immunological tolerance and explore the role tolerance plays in determination of susceptibility to such adverse events even in individuals carrying immunogenic liabilities.

Modern Advances in CARs Therapy and Creating a New Approach to Future Treatment

Genetically engineered T and NK cells expressing a chimeric antigen receptor (CAR) are promising cytotoxic cells for the treatment of hematological malignancies and solid tumors. Despite the successful therapies using CAR-T cells, they have some disadvantages, such as cytokine release syndrome (CRS), neurotoxicity, or graft-versus-host-disease (GVHD). CAR-NK cells have lack or minimal cytokine release syndrome and neurotoxicity, but also multiple mechanisms of cytotoxic activity. NK cells are suitable for developing an "off the shelf" therapeutic product that causes little or no graft versus host disease (GvHD), but they are more sensitive to apoptosis and have low levels of gene expression compared to CAR-T cells. To avoid these adverse effects, further developments need to be considered to enhance the effectiveness of adoptive cellular immunotherapy. A promising approach to enhance the effectiveness of adoptive cellular immunotherapy is overcoming terminal differentiation or senescence and exhaustion of T cells. In this case, EVs derived from immune cells in combination therapy with drugs may be considered in the treatment of cancer patients, especially effector T and NK cells-derived exosomes with the cytotoxic activity of their original cells.

Pyroptosis: A new insight of non-small-cell lung cancer treatment

Non-small cell lung cancer (NSCLC) has become one of the most common malignant tumors. Emerging evidence has shown that tumor resistance to apoptosis by damaging or bypassing apoptotic cell death is a major contributor to poor responses to therapy in patients with NSCLC. Pyroptosis is a new type of cytolytic and inflammatory programmed death distinct from apoptosis. Currently, pyroptosis has been reported to cause a strong inflammatory response and significant tumor suppression. It is considered a promising therapeutic strategy and prognosis for NSCLC. In this review, we summarized the characteristics of pyroptosis from its underlying basis and role in NSCLC, thereby providing the potential of pyroptosis as a therapeutic strategy and highlighting the challenges of activating pyroptosis in NSCLC treatment.

Granzyme B Turns Nanoparticle Fluorescence "On" for Imaging Cytotoxic T Lymphocyte Activity in Vivo

Cytotoxic T lymphocytes (CTLs) are important immune cells, and their activation is a key step for cancer immunotherapy. Precise evaluation of CTL activity in vivo provides a powerful tool for monitoring cancer-immunotherapeutic outcomes, yet it faces tremendous challenges. Herein, by rationally designing a near-infrared (NIR) fluorescence probe Cys(StBu)-Ile-Glu-Phe-Asp-Lys(Cy5.5)-CBT (Cy5.5-CBT) and employing a reduction-instructed CBT-Cys click condensation reaction, we developed the fluorescence "dual quenched" nanoparticles Cy5.5-CBT-NPs for imaging of granzyme B (GraB), a biomarker tightly associated with the tumoricidal activity of CTLs. Upon GraB cleavage, Cy5.5-CBT-NPs disassembled, subtly turning the fluorescence signal "on". With this fluorescence "turn-on" property, Cy5.5-CBT-NPs enabled sensitive and real-time monitoring of GraB-mediated CTL responses against cancer cells in vitro. Animal experiments demonstrated that, at 16 h post injection, the fluorescence imaging signal of Cy5.5-CBT-NPs showed a 3.1-fold increase on the tumor sites of mice treated by an immune-activating drug S-(2-boronoethyl)-L-cysteine hydrochloride. We envision that Cy5.5-CBT-NPs may provide a powerful tool for noninvasive and sensitive evaluation of immunotherapeutic efficacy of cancer in the near future.

Pore forming-mediated intracellular protein delivery for enhanced cancer immunotherapy

Directly delivering therapeutic proteins to their intracellular targets remains a great challenge. Here, we apply CD8⁺ T cells to form pores on the tumor cells' plasma membranes, enabling perfusion of ribonuclease A (RNase A) and granzyme B into cells, therefore effectively inducing tumor apoptosis and pyroptosis by activating caspase 3 and gasdermin E pathways to potentiate the CD8⁺ T cell-mediated immunotherapy. Then, RNase A, programmed cell death ligand 1 antibody, and a photothermal agent were further loaded into an injectable hydrogel to treat the low immunogenic murine breast cancer. Notably, three courses of laser irradiation induced efficient cell apoptosis and immune activation, resulting in a notable therapeutic efficacy that 75% of the tumors were ablated without relapse.

Immune Response Gaps Linked to SARS-CoV-2 Infection: Cellular Exhaustion, Senescence, or Both?

The COVID-19 pandemic, promoted by the SARS-CoV-2 respiratory virus, has resulted in widespread global morbidity and mortality. The immune response against this pathogen has shown a thin line between protective effects and pathological reactions resulting from the massive release of cytokines and poor viral clearance. The latter is possibly caused by exhaustion, senescence, or both of TCD8+ cells and reduced activity of natural killer (NK) cells. The imbalance between innate and adaptive responses during the early stages of infection caused by SARS-CoV-2 contributes to the ineffective control of viral spread. The present study evaluated the tissue immunoexpression of the tissue biomarkers (Arginase-1, CCR4, CD3, CD4, CD8, CD20, CD57, CD68, CD138, IL-4, INF-α, INF-γ, iNOS, PD-1, Perforin and Sphingosine-1) to understand the cellular immune response triggered in patients who died of COVID-19. We evaluated twenty-four paraffin-embedded lung tissue samples from patients who died of COVID-19 (COVID-19 group) and compared them with ten lung tissue samples from patients who died of H1N1pdm09 (H1N1 group) with the immunohistochemical markers mentioned above. In addition, polymorphisms in the Perforin gene were genotyped through Real-Time PCR. Significantly increased tissue immunoexpression of Arginase, CD4, CD68, CD138, Perforin, Sphingosine-1, and IL-4 markers were observed in the COVID-19 group. A significantly lower immunoexpression of CD8 and CD57 was also found in this group. It is suggested that patients who died from COVID-19 had a poor cellular response concerning viral clearance and adaptive response going through tissue repair.

Different modalities of host cell death and their impact on Mycobacterium tuberculosis infection

Mycobacterium tuberculosis (Mtb) is the pathogen that causes tuberculosis (TB), a leading infectious disease of humans worldwide. One of the main histopathological hallmarks of TB is the formation of granulomas comprised of elaborately organized aggregates of immune cells containing the pathogen. Dissemination of Mtb from infected cells in the granulomas due to host and mycobacterial factors induces multiple cell death modalities in infected cells. Based on molecular mechanism, morphological characteristics, and signal dependency, there are two main categories of cell death: programmed and nonprogrammed. Programmed cell death (PCD), such as apoptosis and autophagy, is associated with a protective response to Mtb by keeping the bacteria encased within dead macrophages that can be readily phagocytosed by arriving in uninfected or neighboring cells. In contrast, non-PCD necrotic cell death favors the pathogen, resulting in bacterial release into the extracellular environment. Multiple types of cell death in the PCD category, including pyroptosis, necroptosis, ferroptosis, ETosis, parthanatos, and PANoptosis, may be involved in Mtb infection. Since PCD pathways are essential for host immunity to Mtb, therapeutic compounds targeting cell death signaling pathways have been experimentally tested for TB treatment. This review summarizes different modalities of Mtb-mediated host cell deaths, the molecular mechanisms underpinning host cell death during Mtb infection, and its potential implications for host immunity. In addition, targeting host cell death pathways as potential therapeutic and preventive approaches against Mtb infection is also discussed.