Target cell apoptosis induced by cytotoxic T cells and natural killer cells involves synergy between the pore-forming protein, perforin, and the serine protease, granzyme B

Immune Rejection Mediated by prf1 and gzmb Affects the Colonization of Fat Greenling (Hexagrammos otakii) Spermatogonia in Heterotransplantation

Fish germ cell transplantation holds great potential for conserving endangered species, improving cultured fish breeds, and exploring reproductive techniques. However, low transplantation efficiency is a common issue in heterotransplantation. This study transplanted fat greenling (Hexagrammos otakii) spermatogonia into the testes of spotted sea bass (Lateolabrax maculatus) to investigate factors that might affect the colonization and fixation of heterologous transplanted germ cells. Results indicated that transplanted fat greenling spermatogonia cells were successfully detected in the early transplantation phase in spotted sea bass. Their numbers gradually decreased over time, and after 10 days post-transplantation, more than 90% of the transplanted cells underwent apoptosis. Transcriptome sequencing analysis of the testes of spotted sea bass and fat greenling spermatogonia on days 1 and 10 post-transplantation revealed that this apoptosis process involved many immune-related genes and their associated signaling pathways. Acute immune rejection marker genes prf1 and gzmb were detected in the spotted sea bass testes, while immune tolerance genes lck and zap-70 were expressed in the fat greenling spermatogonia. Additionally, differential expression of prf1 and gzmb genes was screened from spotted sea bass, with experimental evidence indicating that PRF1 and GZMB protein from spotted sea bass primarily induce apoptosis in transplanted fat greenling spermatogonia via the mitochondrial apoptosis pathway, at the protein level. This suggests that the difficulties in heterotransplantation are primarily related to acute immune rejection, with PRF1 and GZMB playing significant roles.

Arming oncolytic viruses with bispecific T cell engagers: The evolution and current status

Oncolytic viruses (OVs) are emerging as therapeutically relevant anticancer agents as contemporary immunotherapy gains traction. Furthermore, OVs are an ideal platform for genetic modification to express therapeutic transgenes. Bispecific T cell engagers (BiTEs) can redirect T cells to tumor cells, resulting in targeted cytotoxicity. BiTEs have demonstrated success in hematological cancers but are rarely used in solid tumors. The drawbacks of BiTEs, including inadequate delivery and on-target-off-tumor activity have limited their efficacy. Combining OVs with BiTEs is a prospective area to investigate. This combined strategy can benefit from the best qualities of both therapies while overcoming the limitations.

Circulating cytotoxic immune cell composition, activation status and toxins expression associate with white matter microstructure in bipolar disorder

Patients with bipolar disorder (BD) show higher immuno-inflammatory setpoints, with in vivo alterations in white matter (WM) microstructure and post-mortem infiltration of T cells in the brain. Cytotoxic CD8+ T cells can enter and damage the brain in inflammatory disorders, but little is known in BD. Our study aimed to investigate the relationship between cytotoxic T cells and WM alterations in BD. In a sample of 83 inpatients with BD in an active phase of illness (68 depressive, 15 manic), we performed flow cytometry immunophenotyping to investigate frequencies, activation status, and expression of cytotoxic markers in CD8+ and tested for their association with diffusion tensor imaging (DTI) measures of WM microstructure. Frequencies of naïve and activated CD8+ cell populations expressing Perforin, or both Perforin and Granzyme, negatively associated with WM microstructure. CD8+ Naïve cells negative for Granzyme and Perforin positively associates with indexes of WM integrity, while the frequency of CD8+ memory cells negatively associates with index of WM microstructure, irrespective of toxins expression. The resulting associations involve measures representative of orientational coherence and myelination of the fibers (FA and RD), suggesting disrupted oligodendrocyte-mediated myelination. These findings seems to support the hypothesis that immunosenescence (less naïve, more memory T cells) can detrimentally influence WM microstructure in BD and that peripheral CD8+ T cells may participate in inducing an immune-related WM damage in BD mediated by killer proteins.

Modulation of natural killer cell exhaustion in the lungs: the key components from lung microenvironment and lung tumor microenvironment

Lung cancer is the leading cause of tumor-induced death worldwide and remains a primary global health concern. In homeostasis, due to its unique structure and physiological function, the lung microenvironment is in a state of immune tolerance and suppression, which is beneficial to tumor development and metastasis. The lung tumor microenvironment is a more complex system that further enhances the immunosuppressive features in the lungs. NK cells are abundantly located in the lungs and play crucial roles in lung tumor surveillance and antitumor immunity. However, the immunosuppressive microenvironment promotes significant challenges to NK cell features, leading to their hypofunction, exhaustion, and compromised antitumor activity. Thus, understanding the complex interactions among the lung microenvironment, lung tumor microenvironment, and NK cell exhaustion is critical for the development of effective cancer immunotherapeutic strategies. The present review will discuss NK cell hypofunction and exhaustion within the lung microenvironment and lung tumor microenvironment, focusing on lung tissue-specific factors, including key cytokines and unique environmental components, that modulate NK cell activation and function. Understanding the functional mechanisms of key factors would help to design strategies to reverse NK cell exhaustion and restore their antitumor function within the lung tumor microenvironment.

Acute Lymphoblastic Leukemia Immunotherapy Treatment: Now, Next, and Beyond

Acute lymphoblastic leukemia (ALL) is a blood cancer that primarily affects children but also adults. It is due to the malignant proliferation of lymphoid precursor cells that invade the bone marrow and can spread to extramedullary sites. ALL is divided into B cell (85%) and T cell lineages (10 to 15%); rare cases are associated with the natural killer (NK) cell lineage (<1%). To date, the survival rate in children with ALL is excellent while in adults continues to be poor. Despite the therapeutic progress, there are subsets of patients that still have high relapse rates after chemotherapy or hematopoietic stem cell transplantation (HSCT) and an unsatisfactory cure rate. Hence, the identification of more effective and safer therapy choices represents a primary issue. In this review, we will discuss novel therapeutic options including bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor (CAR)-based therapies, and other promising treatments for both pediatric and adult patients.

Molecular Farming of Pembrolizumab and Nivolumab

Immune checkpoint inhibitors (ICIs) are a class of immunotherapy agents capable of alleviating the immunosuppressive effects exerted by tumorigenic cells. The programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint is one of the most ubiquitous checkpoints utilized by tumorigenic cells for immune evasion by inducing apoptosis and inhibiting the proliferation and cytokine production of T lymphocytes. Currently, the most frequently used ICIs targeting the PD-1/PD-L1 checkpoint include monoclonal antibodies (mAbs) pembrolizumab and nivolumab that bind to PD-1 on T lymphocytes and inhibit interaction with PD-L1 on tumorigenic cells. However, pembrolizumab and nivolumab are costly, and thus their accessibility is limited in low- and middle-income countries (LMICs). Therefore, it is essential to develop novel biomanufacturing platforms capable of reducing the cost of these two therapies. Molecular farming is one such platform utilizing plants for mAb production, and it has been demonstrated to be a rapid, low-cost, and scalable platform that can be potentially implemented in LMICs to diminish the exorbitant prices, ultimately leading to a significant reduction in cancer-related mortalities within these countries.

Granzyme B: A novel therapeutic target for treatment of atopic dermatitis

Granzyme B is a serine protease that can play multiple roles in intracellular and extracellular perforin-dependent or non-perforin-dependent mechanisms. Granzyme B has been found to be an important factor involved in the pathogenesis of atopic dermatitis and is increased in both skin lesions and peripheral blood of atopic dermatitis patients. In this article, we review the correlation between granzyme B and atopic dermatitis to provide a novel therapeutic targeting option for clinical treatment of the latter.

Plasmalogen-Mediated Activation of GPCR21 Regulates Cytolytic Activity of NK Cells against the Target Cells

It is widely known that the immune system becomes slower to respond among elderly people, making them more susceptible to viral infection and cancer. The mechanism of aging-related immune deficiency remained mostly elusive. In this article, we report that plasmalogens (Pls), special phospholipids found to be reduced among the elderly population, critically control cytolytic activity of human NK cells, which is associated with activation of a cell surface receptor, G protein-coupled receptor 21 (GPCR21). We found the extracellular glycosylation site of GPCR21, which is conserved among the mammalian species, to be critically important for the activation of NK cells by Pls. The Pls-GPCR21 signaling cascade induces the expression of Perforin-1, a cytolytic pore-forming protein, via activation of STAT5 transcription factor. Inhibition of STAT5 abrogates GPCR21-mediated cytolytic activation of NK cells against the target cancer cells. In addition, oral ingestion of Pls inhibited cancer growth in SCID mice and inhibited the systemic spread of murine CMV in adult C57BL/6J mice. These findings advocate that Pls-GPCR21 signaling could be critical in maintaining NK cell function, and that the age-related reduction of this signaling cascade could be one of the factors behind immune deficiency in mammals, including humans.

Role of Histone Deacetylases in T-Cell Development and Function

Histone deacetylases (HDACs) are a group of enzymes called “epigenetic erasers”. They remove the acetyl group from histones changing the condensation state of chromatin, leading to epigenetic modification of gene expression and various downstream effects. Eighteen HDACs have been identified and grouped into four classes. The role of HDACs in T-cells has been extensively studied, and it has been proven that many of them are important players in T-cell development and function. In this review, we present the current state of knowledge on the role of HDACs in the early stages of T-cell development but also in the functioning of mature lymphocytes on the periphery, including activation, cytokine production, and metabolism regulation.

Scale-out production of extracellular vesicles derived from natural killer cells via mechanical stimulation in a seesaw-motion bioreactor for cancer therapy

Extracellular vesicles (EVs) derived from immune cells have shown great anti-cancer therapeutic potential. However, inefficiency in EV generation has considerably impeded the development of EV-based basic research and clinical translation. Here, we developed a seesaw-motion bioreactor (SMB) system by leveraging mechanical stimuli such as shear stress and turbulence for generating EVs with high quality and quantity from natural killer (NK) cells. Compared to EV production in traditional static culture (229 ± 74 particles per cell per day), SMB produced NK-92MI-derived EVs at a higher rate of 438 ± 50 particles per cell per day and yielded a total number of 2 × 1011 EVs over two weeks via continuous dynamic fluidic culture. In addition, the EVs generated from NK-92MI cells in SMB shared a similar morphology, size distribution, and protein profile to EVs generated from traditional static culture. Most importantly, the NK-92MI-derived EVs in SMB were functionally active in killing melanoma and liver cancer cells in both 2D and 3D culture conditions in vitro, as well as in suppressing melanoma growth in vivo. We believe that SMB is an attractive approach to producing EVs with high quality and quantity; it can additionally enhance EV production from NK92-MI cells and promote both the basic and translational research of EVs.

Single-cell RNA sequencing predicts motility networks in purified human gastric interstitial cells of Cajal

BACKGROUND

Gastrointestinal (GI) motility disorders affect millions of people worldwide, yet they remain poorly treated in part due to insufficient knowledge of the molecular networks controlling GI motility. Interstitial cells of Cajal (ICC) are critical GI pacemaker cells, and abnormalities in ICC are implicated in GI motility disorders. Two cell surface proteins, KIT and ANO1, are used for identifying ICC. However, difficulties accessing human tissue and the low frequency of ICC in GI tissues have meant human ICC are insufficiently characterized. Here, a range of characterization assays including single-cell RNA sequencing (scRNA-seq) was performed using KIT⁺ CD45^- CD11B^- primary human gastric ICC to better understand networks controlling human ICC biology.

METHODS

Excess sleeve gastrectomy tissues were dissected; ICC were analyzed by immunofluorescence, fluorescence-activated cell sorting (FACSorting), real-time PCR, mass spectrometry, and scRNA-seq.

KEY RESULTS

Immunofluorescence identified ANO1⁺ /KIT⁺ cells throughout the gastric muscle. Compared to the FACSorted negative cells, PCR showed the KIT⁺ CD45^- CD11B^- ICC were enriched 28-fold in ANO1 expression (p < 0.01). scRNA-seq analysis of the KIT^- CD45⁺ CD11B⁺ and KIT⁺ CD45^- CD11B^- ICC revealed separate clusters of immune cells and ICC (respectively); cells in the ICC cluster expressed critical GI motility genes (eg, CAV1 and PRKG1). The scRNA-seq data for these two cell clusters predicted protein interaction networks consistent with immune cell and ICC biology, respectively.

CONCLUSIONS & INFERENCES

The single-cell transcriptome of purified KIT⁺ CD45^- CD11B^- human gastric ICC presented here provides new molecular insights and hypotheses into evolving models of GI motility. This knowledge will provide an improved framework to investigate targeted therapies for GI motility disorders.

The mosaic puzzle of the therapeutic monoclonal antibodies and antibody fragments - A modular transition from full-length immunoglobulins to antibody mimetics

The use of monoclonal antibodies represents an important and efficient diagnostic and therapeutic tool in disease management and modern science but remains limited by several factors including the uneven distribution in diseased tissues as well as undesired activation of side immune reactions. Major scientific advancements including Recombinant DNA Technology, Hybridoma Technology, and Polymerase Chain Reaction have considerably impacted the use of monoclonal antibodies providing technical and effective solutions to overcome the shortcomings encountered with conventional antibodies. Initially, the introduction of antibody fragments allowed a more uniform and deeper penetration of the targeted tissue and reduced unwanted activation of Fc-mediated immune reactions. On another level, the immunogenicity of murine-derived antibodies was overcome by humanizing their encoding genes with specific sequences of human origin andtransgenic mice able to synthesize fully human antibodies were successfully created. Moreover, the advancement of genetic engineering techniques supported by the modular structure of antibody coding genes paved the way for the development of a new generation of antibody fragments with a wide spectrum of monospecific and bispecific agents. These later could be monovalent, bivalent, or multivalent, and either expressed as a single chain, assembled in multimeric forms or stringed in tandem. This has conferred improved affinity, stability, and solubility to antibody targetting. Lately, a new array of monoclonal antibody fragments was introduced with the engineering of nanobody and antibody mimetics as non-immunoglobulin-derived fragments with promising diagnostic and therapeutic applications. In this review, we decipher the molecular basis of monoclonal antibody engineering with a detailed screening of the antibody derivatives that provides new perspectives to expand the use of monoclonal fragments into previously unexplored fields.

LFA-1 activation enriches tumor-specific T cells in a cold tumor model and synergizes with CTLA-4 blockade

The inability of CD8⁺ effector T cells (Teffs) to reach tumor cells is an important aspect of tumor resistance to cancer immunotherapy. The recruitment of these cells to the tumor microenvironment (TME) is regulated by integrins, a family of adhesion molecules that are expressed on T cells. Here, we show that 7HP349, a small-molecule activator of lymphocyte function–associated antigen-1 (LFA-1) and very late activation antigen-4 (VLA-4) integrin cell-adhesion receptors, facilitated the preferential localization of tumor-specific T cells to the tumor and improved antitumor response. 7HP349 monotherapy had modest effects on anti–programmed death 1–resistant (anti–PD-1–resistant) tumors, whereas combinatorial treatment with anti–cytotoxic T lymphocyte–associated protein 4 (anti–CTLA-4) increased CD8⁺ Teff intratumoral sequestration and synergized in cooperation with neutrophils in inducing cancer regression. 7HP349 intratumoral CD8⁺ Teff enrichment activity depended on CXCL12. We analyzed gene expression profiles using RNA from baseline and on treatment tumor samples of 14 melanoma patients. We identified baseline CXCL12 gene expression as possibly improving the likelihood or response to anti–CTLA-4 therapies. Our results provide a proof-of-principle demonstration that LFA-1 activation could convert a T cell–exclusionary TME to a T cell–enriched TME through mechanisms involving cooperation with innate immune cells.

A Gene Panel for Early Identification of Future Responders to Immune Checkpoint Blockade

Immune checkpoint blockade (ICB), therapies that target the PD-1 pathway, CTLA-4 pathway, and other checkpoint pathways, lead to durable responses in many cancer types. Since only a minority of patients respond to ICB, it may be useful to identify the future responders early in the course of treatment. In this study we evaluated a small (15 genes) biologically motivated panel, consisting of genes involved in immune activation and checkpoint pathways, for early identification of future responders to ICB. The panel passed consistency check, pathological and in-silico validations, and was an excellent predictor (area under ROC curve >0.95) of eventual response to ICB, both CTLA-4 and PD-1 blockade, when applied to metastatic melanoma patients undergoing ICB (i.e., “on-treatment”) in a publicly available dataset. These results suggest that this small biologically motivated panel may be useful for early identification of future responders to ICB.

Histocompatibility and Reproduction: Lessons from the Anglerfish

Reproduction in certain deep-sea anglerfishes involves the permanent attachment of dwarf males to much larger females and fusion of their tissues leading to the establishment of a shared circulatory system. This unusual phenomenon of sexual parasitism enables anglerfishes to maximize reproductive success in the vast and deep oceans, where females and males otherwise rarely meet. An even more surprising phenomenon relates to the observation that joining of genetically disparate male and female anglerfishes does not evoke a strong anti-graft immune rejection response, which occurs in vertebrates following allogeneic parabiosis. Recent studies demonstrated that the evolutionary processes that led to the unique mating strategy of anglerfishes coevolved with genetic changes that resulted in loss of functional genes encoding critical components of the adaptive immune system. These genetic alterations enabled anglerfishes to tolerate the histoincompatible tissue antigens of their mate and prevent the occurrence of reciprocal graft rejection responses. While the exact mechanisms by which anglerfishes defend themselves against pathogens have not yet been deciphered, it is speculated that during evolution, anglerfishes adopted new immune strategies that compensate for the loss of B and T lymphocyte functions and enable them to resist infection by pathogens.

Supplementation with a Natural Source of Amino Acids, Sil-Q1 (Silk Peptide), Enhances Natural Killer Cell Activity: A Redesigned Clinical Trial with a Reduced Supplementation Dose and Minimized Seasonal Effects in a Larger Population

The aim of this study was to re-validate the changes in natural killer (NK) cell cytotoxicity and cytokines related to T cells after Sil-Q1 (SQ; silk peptide) supplementation in a larger pool of Korean adults with minimized daily dose of SQ and controlling seasonal influence compared to the previous study. A total of 130 subjects were randomly assigned (1:1) to consume either 7.5 g of SQ or placebo for 8 weeks. NK cell cytotoxicity and cytokines were measured at T0 (baseline) and T8 (follow-up). Comparing the NK cell cytotoxicity values at T0 and T8 within each group, the cytotoxicity at all effector cell (E) to target cell (T) ratios of 10:1, 5:1, 2.5:1, and 1.25:1 was significantly increased in the SQ group at T8. Additionally, significant differences in the changed value (Δ, subtract baseline values from follow-up values) comparison between the groups at E:T = 10:1, 5:1, and 2.5:1 were found. As a secondary endpoint, the interleukin (IL)-12 level in the SQ group was significantly increased for 8 weeks, and Δ IL-12 in the SQ group was greater than in the placebo group. In conclusion, the present study showed considerable practical implications of SQ supplementation. Thus, SQ is an effective and safe functional food supplement for enhancing immune function.

Bispecific T cell engagers: an emerging therapy for management of hematologic malignancies

Harnessing the power of immune cells, especially T cells, to enhance anti-tumor activities has become a promising strategy in clinical management of hematologic malignancies. The emerging bispecific antibodies (BsAbs), which recruit T cells to tumor cells, exemplified by bispecific T cell engagers (BiTEs), have facilitated the development of tumor immunotherapy. Here we discussed the advances and challenges in BiTE therapy developed for the treatment of hematologic malignancies. Blinatumomab, the first BiTE approved for the treatment of acute lymphocytic leukemia (ALL), is appreciated for its high efficacy and safety. Recent studies have focused on improving the efficacy of BiTEs by optimizing treatment regimens and refining the molecular structures of BiTEs. A considerable number of bispecific T cell-recruiting antibodies which are potentially effective in hematologic malignancies have been derived from BiTEs. The elucidation of mechanisms of BiTE action and neonatal techniques used for the construction of BsAbs can improve the treatment of hematological malignancies. This review summarized the features of bispecific T cell-recruiting antibodies for the treatment of hematologic malignancies with special focus on preclinical experiments and clinical studies.

NF-κB c-Rel Is Dispensable for the Development but Is Required for the Cytotoxic Function of NK Cells

Natural Killer (NK) cells are cytotoxic lymphocytes critical to the innate immune system. We found that germline deficiency of NF-κB c-Rel results in a marked decrease in cytotoxic function of NK cells, both in vitro and in vivo, with no significant differences in the stages of NK cell development. We found that c-Rel binds to the promoters of perforin and granzyme B, two key proteins required for NK cytotoxicity, and controls their expression. We generated a NK cell specific c-Rel conditional knockout to study NK cell intrinsic role of c- Rel and found that both global and conditional c-Rel deficiency leads to decreased perforin and granzyme B expression and thereby cytotoxic function. We also confirmed the role of c-Rel in perforin and granzyme B expression in human NK cells. c-Rel reconstitution rescued perforin and granzyme B expressions in c-Rel deficient NK cells and restored their cytotoxic function. Our results show a previously unknown role of c-Rel in transcriptional regulation of perforin and granzyme B expressions and control of NK cell cytotoxic function.

Decrease in immune function and the role of mitogen-activated protein kinase (MAPK) overactivation in apoptosis during T lymphocytes activation induced by zearalenone, deoxynivalenol, and their combinations

Currently there are few reports on the combined immunotoxicity of zearaleone (ZEA) and deoxynivalenol (DON). Since the two coexist naturally, it is necessary to understand the immunotoxicity caused by the two mycotoxins alone and in combination. To examine T lymphocytes activation and immune effect during activation, we used mouse primary spleen T lymphocytes as the experimental material and concanavalin (Con A) as the stimulator. The effects of ZEA, DON, and their combined exposure on T lymphocytes immune related function and the relationship between the activation of the mitogen-activated protein kinase (MAPK) signaling pathway and mycotoxin induced T lymphocytes apoptosis were studied in vitro. Specifically, T lymphocytes were isolated from primary mouse splenic lymphocytes, activated by Con A and then exposed to different concentrations of ZEA, DON, and their combinations. Our results showed that ZEA and DON alone and their combinations (20:1) can decrease the cell viability of T lymphocytes activated by Con A. The inhibitory effect of the combined groups was greater than that of the single mycotoxins, showing a synergistic effect. In addition, single or combined mycotoxins can lead to intracellular and surface ultrastructure damage of T lymphocytes, inhibit the expression of CD25 and CD278 and inhibit the synthesis of effect molecules poreforming protein (PFP), granzyme A (GZMA), and tumor necrosis factor-α (TNF-α). Meanwhile, the single mycotoxin or combined mycotoxins can promote the apoptosis of T lymphocytes which was accompanied by the overactivation of MAPK. After using the inhibitors of extracellular regulated protein kinases (ERK) and c-Jun N-terminal kinase (JNK) in the MAPK pathway, we found that the apoptosis of the cells induced by the ZEA was significantly decreased, and the apoptosis of the cells induced by DON had no significant changes. This suggests that the activation of MAPK induced by ZEA can promote the apoptosis of T lymphocytes, but the activation of MAPK induced by DON is not directly related to T cell apoptosis.

Inhibition of SHP-1 Expands the Repertoire of Antitumor T Cells Available to Respond to Immune Checkpoint Blockade

The presence and activity of CD8⁺ T cells within the tumor microenvironment are essential for the control of tumor growth. Utilizing B16-F10 melanoma tumors that express altered peptide ligands of chicken ovalbumin, OVA_257-264, we measured high- and low-affinity OVA-specific responses following adoptive transfer of OT-I CD8⁺ T cell into mice subsequently challenged with tumors. T-cell receptor (TCR) affinity positively correlated with the frequency of OT-I tumor-infiltrating lymphocytes (TIL). Differences in TCR affinity inversely corresponded to in vivo tumor growth rate. Blockade of the PD-1 and CTLA-4 checkpoints preferentially increased the frequency and antitumor function of TIL responding to high-affinity antigens, while failing to enhance the antitumor activity of low-affinity T cells. To determine whether lowering the TCR activation threshold could enhance the breadth and magnitude of the antitumor T-cell response, we inhibited Src homology region 2 domain-containing phosphatase 1 (SHP-1) in OT-I T cells prior to tumor antigen exposure. SHP-1 knockdown increased the cytokine-producing potential of high- and low-affinity T cells but failed to enhance control of tumor growth. In contrast, when SHP-1 knockdown of OT-I T cells was combined with immunotherapy, we observed a significant and long-lasting suppression of tumor growth mediated by low-affinity T cells. We conclude that lowering the TCR activation threshold by targeting SHP-1 expands the repertoire of T cells available to respond to conventional checkpoint blockade, leading to enhanced control of tumor growth.

Actin Cytoskeleton Straddling the Immunological Synapse between Cytotoxic Lymphocytes and Cancer Cells

The immune system is a fundamental part of the tumor microenvironment. In particular, cytotoxic lymphocytes, such as cytolytic T cells and natural killer cells, control tumor growth and disease progression by interacting and eliminating tumor cells. The actin cytoskeleton of cytotoxic lymphocytes engaged in an immunological synapse has received considerable research attention. It has been recognized as a central mediator of the formation and maturation of the immunological synapse, and its signaling and cytolytic activities. In comparison, fewer studies have explored the organization and function of actin filaments on the target cancer cell side of the immunological synapse. However, there is growing evidence that the actin cytoskeleton of cancer cells also undergoes extensive remodeling upon cytotoxic lymphocyte attack, and that such remodeling can alter physical and functional interactions at the immunological synapse. In this article, we review the current knowledge of actin organization and functions at both sides of the immunological synapse between cytotoxic lymphocytes and cancer cells, with particular focus on synapse formation, signaling and cytolytic activity, and immune evasion.

Effect of weaning age on growth, mammary gland development, and immune function in Holstein Friesian calves fed conserved alfalfa (FiberStart)

This study aimed to evaluate intake, body growth, and the development of the rumen, mammary gland, and immune system in Holstein Friesian calves reared for 100 d on the commercially available feed FiberStart (conserved alfalfa, Medicago sativa; Fiber Fresh Feeds Ltd., Reporoa, New Zealand) and fed calf milk replacer (CMR) for either 56 or 91 d. Eighty calves (40 bulls and 40 heifer calves) were reared indoors in groups (n = 5 of the same sex/pen). All calves were fed 4 L of CMR/d (175 g/L of CMR) in 2 feeds/d for the first 10 d and then 1 feed/d until d 49 or 84. The calves were gradually weaned by d 56 (earlier weaned; n = 8 pens) and d 91 (later weaned; n = 8 pens). All calves were fed FiberStart ad libitum as the only solid feed source from d 1 to 100 of the study. Irrespective of treatment, all calves had similar body weights at d 0 (40.9 ± 3.0 kg) and d 49 (74.2 ± 5.1 kg) of the study. Calf sex had no effect on intake, growth, blood, and immune system parameters. Earlier-weaned calves consumed 18% more solid feed dry matter but had 16% lower body weight gain (28.9 vs. 38.5 kg, respectively) from d 56 to 100 relative to later-weaned calves, resulting in different body weight at 100 d (104 vs. 121 ± 1.3 kg). Although earlier-weaned calves could compensate for the loss of CMR dry matter and crude protein intake from d 56 to 100 by increasing forage intake, they were unable to compensate for the loss of energy from the CMR by increasing solid feed consumption. Plasma β-hydroxybutyrate concentrations were 52% greater in earlier-weaned calves than in later-weaned calves at d 84, indicating greater metabolic activity of the rumen wall. The duration of CMR feeding had no influence on humoral or cell-mediated immune functions of the calves, as evidenced by a lack of effect on antivaccine antibody responses as well as on immune gene expression. Earlier- versus later-weaned heifer calves had 5% lower mammary gland mass, indicating that greater energy supply increased mammary mass. The results of this experiment demonstrate the ability to artificially rear dairy calves on a conserved alfalfa as the only solid feed. Furthermore, earlier weaning off CMR promotes solid feed intake and an associated increase in blood β-hydroxybutyrate, an indicator of rumen development, but increasing the duration of CMR feeding improves growth and mammary gland mass by d 100. The implications of these findings on lifetime growth, health, and milk production in dairy heifers warrant further investigation.

Epigenetic modulation enhances immunotherapy for hepatocellular carcinoma

BACKGROUND

Anti-PDL-1 immunotherapy for Hepatocellular Carcinoma (HCC) demonstrated a mixed response. Polycomb Repressor Complex 2(PRC2) contributes to the initiation and progression of HCC by suppressing tumor antigens and inhibiting an immune response. Two components of epigenetic modulation are Enhancer of Zeste Homolog 2 (EZH2, the catalytic component of PRC2) and DNA Methyltransferase 1 (DNMT1). We aim to investigate the potential role of epigenetic therapy targeting EZH2 and DNMT1 as a novel strategy to modulate immunotherapy response in HCC.

METHODS

HepG2, Hep3B, and Hepa1-6 HCC cell lines were treated with EZH2 inhibitor (DZNep) and DNMT1 inhibitor (5-Azacytidine) with and without anti-PDL-1. Quantitative RT-PCR and immunohistochemistry were performed to evaluate the expression of tumor suppressors, tumor antigens, and Th1 chemokines. In-vivo C57/LJ immunocompetent mice model with subcutaneous tumor inoculation was performed with intraperitoneal drug injections.

RESULTS

There was a significant upregulation of Th1 chemokines in HepG2 (CXCL9 5.5 ± 0.2 relative fold change; CXCL10 1.44 × 103 ± 37 relative fold change) and Hep3B (CXCL 9 6.85 × 103 ± 1.3 × 103 relative fold change; CXCL 10 2.15 × 103 ± 3.1 × 102 relative fold change). Additionally, there was a significant induction of cancer testis antigens NY-ESO-1 (3.6-3.7 ± 0.3 relative fold change) and LAGE (8.3-11.7 ± 1.9 relative fold change). In vivo model demonstrated statistically significant tumor regression in the combination treatment group (0.02 g ± 0.02) compared to epigenetic therapy (0.63 g ± 0.61) or immunotherapy alone (0.15 g ± 0.21) with untreated control (2.4 g ± 0.71). There was significantly increased trafficking of cytotoxic T- lymphocytes and associated apoptosis for the combination treatment group compared to epigenetic or immunotherapy alone.

CONCLUSIONS

This study demonstrates that epigenetic modulation could be a novel potential strategy to augment immunotherapy for HCC by stimulating T cell trafficking into tumor microenvironment via activation of transcriptionally repressed chemokine genes responsible for T-cell trafficking, inducing previously silent neoantigens for immune targets, and allowing tumor regression as a result. A clinical trial of this feasible combination therapy of these clinically available agents is warranted.

Far-off and close-up feeding levels affect immunological performance in grazing dairy cows during the transition period

During the peripartum period, dairy cows often have signs of inflammation. Various stresses, including infectious and metabolic diseases, have been discussed as causative for this inflammation. In this study, expression profiles for 17 immune markers were measured in whole blood preparations from 78 dairy cows over a time frame starting 1 wk before calving to 4 wk after calving. Additionally, the effects of far-off and close-up feeding on immune function of dairy cows during the peripartum period were investigated. Cows were assigned to 1 of 2 feeding levels in late lactation to achieve a low and high BCS at the time of dry-off (approximately 4.25 and 5.0 on a 10-point scale). Following dry-off, both herds were managed to achieve a BCS of 5.0 one month before calving; this involved controlled feeding (i.e., maintenance) and over-feeding of ME during the far-off dry period. Within each far-off feeding-level treatment, cows were offered 65, 90, or 120% of their precalving ME requirements for 3 wk precalving in a 2 × 3 factorial arrangement. Analysis of gene expression profiles from blood cells revealed effects of time indicating that the transition cow's immune system counteracts the peripartum inflammation, whereas later postcalving it becomes activated to provide protection against postpartum infections. Far-off feeding affected (P < 0.05) the expression of 2 of the investigated genes at calving. Interleukin-6 (IL-6) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression in unstimulated, peripheral leukocytes were lower (P < 0.05) in animals from the Far-Off_Over-fed group compared with the Far-Off_Control-fed group. Close-up feeding had several effects on gene expression, indicating that immune function in Feed120 animals was distinct from the Feed90 and Feed65. In conclusion, feeding management precalving becomes an important intervention to ensure immunocompetence at and after calving.

Understanding how combinatorial targeting of TLRs and TNFR family costimulatory members promote enhanced T cell responses

INTRODUCTION

Due to the ability of pathogen-associated molecular patters and tumor necrosis factor receptor (TNFR) family costimulatory agonists to boost T cell responses, studies have combined Toll-like receptor (TLR) ligands with TNFR family costimulatory receptor agonists to induce impressive and long-lasting T cell responses. Although some studies have determined how these combinatorial vaccines promote enhanced T cell responses, much remains unknown about the mechanism used by these combinations to promote synergistic T cell responses - especially in settings of infectious diseases or cancer.

AREAS COVERED

In this review, we look in detail at the signaling pathways induced by combinatorial targeting of TLR and TNFR family costimulatory members that help them promote synergistic T cell responses. Understanding this can greatly aid the development of novel vaccine regimens that promote cellular immune responses, which is essential for treating certain infectious diseases and cancer.

EXPERT OPINION

Vaccines against some infectious diseases as well as therapeutic cancer vaccines require cellular immunity. Therefore, we evaluate here how signaling pathways induced by TLR ligand and costimulatory agonist combinations promote enhanced T cell responses during immunization with model antigens, viral pathogens, or tumor antigens. Once pathways that drive these combinatorial vaccines to boost T cell activation are identified, they can be incorporated in vaccines designed to target pathogens or cancer.

Roles of microRNAs in T cell immunity: Implications for strategy development against infectious diseases

T cell immunity plays a vital role in pathogen infections. MicroRNA (miRNAs) are small, single-stranded noncoding RNAs that regulate T cell immunity by targeting key transcriptional factors, signaling proteins, and cytokines associated with T cell activation, differentiation, and function. The dysregulation of miRNA expression in T cells may lead to specific immune responses and can provide new therapeutic opportunities against various infectious diseases. Here, we summarize recent studies that focus on the roles of miRNAs in T cell immunity and highlight miRNA functions in prevalent infectious diseases. Additionally, we also provide insights into the functions of extracellular vesicle miRNAs and attempt to delineate the mechanism of miRNA sorting into extracellular vesicles and their immunomodulatory functions. Moreover, methodologies and strategies for miRNA delivery against infectious diseases are summarized. Finally, potential strategies for miRNA-based therapies are proposed.

IL-2 augments the therapeutic efficacy of adoptively transferred B cells which directly kill tumor cells via the CXCR4/CXCL12 and perforin pathways

We previously reported that antitumor B cells directly kill tumor cells via the Fas/FasL pathway and are regulated by IL-10. In this study, we defined additional mechanisms involved in B cell antitumor immunity. Administration of IL-2 significantly augmented the therapeutic efficacy of adoptively transferred tumor-draining lymph node (TDLN) B cells which express IL- 2R. Culture supernatant of purified B splenocytes harvested from the mice that received adoptive transfer of 4T1 TDLN B cells plus IL-2 administration produced larger amounts of IgG which bound to 4T1, resulting in 4T1 lysis. Furthermore, we detected CXCR4 expression on 4T1 TDLN B cells, and 4T1 tumor cells produced its ligand CXCL12. Transwell experiments demonstrated the chemoattraction of CXCR4-expressing 4T1 TDLN B cells towards CXCL12- producing 4T1 cells. Blockade of CXCR4 using a CXCR4-specific inhibitor, AMD3100, significantly reduced the killing of 4T1 tumor cells by 4T1 TDLN B cells. Blockade of FasL and CXCR4 concurrently inhibited B cell-mediated direct killing of tumor cells in an additive manner, indicating that both Fas/FasL and CXCL12/CXCR4 pathways are involved in the direct killing of 4T1 cells by 4T1 TDLN B cells. TDLN B cells produced perforin. Additional transwell experiments showed that effector B cells could directly kill tumor cells in cell-cell contact via the Fas/FasL and CXCR4/CXCL12 pathways as well as perforin, while without cell contact, perforin secreted by B cells led to tumor cell cytotoxicity. These findings underscore the diversity of function by which B cells can play an important role in the host immune response to tumor.

QPY/RAH haplotypes of the GZMB gene are associated with natural killer cell cytotoxicity

Granzyme B (GzmB) is a component of cytolytic granules within NK cells and is involved in several pathologies. It has previously been reported that there are three non-synonymous coding SNPs (rs8192917; Q48R, rs11539752; P88A, and rs2236338; Y245H) in the GZMB gene and that the QPY/RAH allele was clustered together close to the C-terminal α-helix. However, it is unknown whether the function of GzmB produced from NK cells is influenced by QPY/RAH polymorphism. The authors investigated the distribution of QPY/RAH polymorphism of the GZMB gene in a Japanese population (n = 106), and the involvement of Q48R polymorphism in NK cell cytotoxicity, degranulation, and production of GzmB. A strong linkage disequilibrium was observed among these SNPs, and NK cell cytotoxicity was influenced by rs8192917 (Q48R). Moreover, it found that R⁴⁸-GzmB is a stable protein that accumulates to similar levels in activated NK cells as Q⁴⁸-GzmB. rs8192917 polymorphism may influence antitumor activity and the effect of antitumor cellular immunotherapy. The authors expect that these new informations about QPY/RAH polymorphism of the GZMB gene could help to assess the impact of NK cell cytotoxicity in several pathologies and aid their treatment.

TCRγ4δ1-engineered αβT cells exhibit effective antitumor activity

T cell engineering with T cell receptors (TCRs) specific for tumors plays an important role in adoptive T-cell transfer (ATC) therapy for cancer. Here, we present a novel strategy to redirect peripheral blood-derived αβT cells against tumors via TCRγ4δ1 gene transduction. The broad-spectrum anti-tumor activity of TCRδ1 cells in innate immunity is dependent on CDR3δ1. TCRγ4δ1-engineered αβT cells were prepared by lentiviral transduction and characterized by analyzing in vitro and in vivo cytotoxicity to tumors, ability of proliferation and cytokine production, and their potential role in autoimmunity. Results show TCRγ4δ1 genes were transduced to approximately 36% of polyclonal αβT cells. TCRγ4δ1-engineered αβT cells exhibited an effective in-vitro TCRγδ-dependent cytotoxicity against various tumor cells via the perforin-granzyme pathway. They also showed a strong proliferative capacity and robust cytokine production. TCRγ4δ1-engineered αβT cells neither expressed mixed TCR dimers nor bound/killed normal cells in vitro. More importantly, adoptive transfer of TCRγ4δ1-engineered αβT cells into nude mice bearing a human HepG2 cell line significantly suppressed tumor growth. Our results demonstrate a novel role for TCRγ4δ1 in gene therapy and ATC for cancer.

ERDR1 enhances human NK cell cytotoxicity through an actin-regulated degranulation-dependent pathway

Erythroid differentiation regulator 1 (ERDR1), which is a stress-related survival factor, exhibits anti-cancer effects against melanoma. However, the function of ERDR1 on immune cells has not been examined. We investigated whether ERDR1 regulates the cytotoxic ability of human natural killer (NK) cells, which are known as innate effector lymphocytes. In this study, treatment with recombinant ERDR1 resulted in enhanced NK cell cytotoxicity through the secretion of lytic granules. Furthermore, actin modulation was involved in the ERDR1-enhanced NK cell cytotoxicity. ERDR1 stimulated actin accumulation at the immunological synapse, which was induced by the activation of Vav-1 in NK cells. These findings suggest new insight into the function of ERDR1 function in the human immune system.

Cyclophosphamide alters the gene expression profile in patients treated with high doses prior to stem cell transplantation

BACKGROUND

Hematopoietic stem cell transplantation is a curative treatment for several haematological malignancies. However, treatment related morbidity and mortality still is a limiting factor. Cyclophosphamide is widely used in condition regimens either in combination with other chemotherapy or with total body irradiation.

METHODS

We present the gene expression profile during cyclophosphamide treatment in 11 patients conditioned with cyclophosphamide for 2 days followed by total body irradiation prior to hematopoietic stem cell transplantation. 299 genes were identified as specific for cyclophosphamide treatment and were arranged into 4 clusters highly down-regulated genes, highly up-regulated genes, early up-regulated but later normalized genes and moderately up-regulated genes.

RESULTS

Cyclophosphamide treatment down-regulated expression of several genes mapped to immune/autoimmune activation and graft rejection including CD3, CD28, CTLA4, MHC II, PRF1, GZMB and IL-2R, and up-regulated immune-related receptor genes, e.g. IL1R2, IL18R1, and FLT3. Moreover, a high and significant expression of ANGPTL1 and c-JUN genes was observed independent of cyclophosphamide treatment.

CONCLUSION

This is the first investigation to provide significant information about alterations in gene expression following cyclophosphamide treatment that may increase our understanding of the cyclophosphamide mechanism of action and hence, in part, avoid its toxicity. Furthermore, ANGPTL1 remained highly expressed throughout the treatment and, in contrast to several other alkylating agents, cyclophosphamide did not influence c-JUN expression.

Adoptive T-cell therapy using autologous tumor-infiltrating lymphocytes for metastatic melanoma: current status and future outlook

Immunotherapy using autologous T cells has emerged to be a powerful treatment option for patients with metastatic melanoma. These include the adoptive transfer of autologous tumor-infiltrating lymphocytes (TILs), T cells transduced with high-affinity T cell receptors against major tumor antigens, and T cells transduced with chimeric antigen receptors composed of hybrid immunoglobulin light chains with endodomains of T-cell signaling molecules. Among these and other options for T-cell therapy, TILs together with high-dose interleukin 2 have had the longest clinical history with multiple clinical trials in centers across the world consistently demonstrating durable clinical response rates near 50% or more. A distinct advantage of TIL therapy making it still the T-cell therapy of choice is the broad nature of the T-cell recognition against both defined and undefined tumors antigens against all possible major histocompatibility complex, rather than the single specificity and limited major histocompatibility complex coverage of the newer T cell receptors and chimeric antigen receptor transduction technologies. In the past decade, significant inroads have been made in defining the phenotypes of T cells in TIL-mediating tumor regression. CD8+ T cells are emerging to be critical, although the exact subset of CD8+ T cells exhibiting the highest clinical activity in terms of memory and effector markers is still controversial. We present a model in which both effector-memory and more differentiated effector T cells ultimately may need to cooperate to mediate long-term tumor control in responding patients. Although TIL therapy has shown great potential to treat metastatic melanoma, a number of issues have emerged that need to be addressed to bring it more into the mainstream of melanoma care. First, we have a reached the point where a pivotal phase II or phase III trial is needed in an attempt to gain regulatory approval of TILs as standard of care. Second, improvements in how we expand TILs for therapy are needed that minimize the time the T cells are in culture and improve the memory and effector characteristics of the T cells for longer persistence and enhanced anti-tumor activity in vivo. Third, there is a critical need to identify surrogate and predictive biomarkers to better select suitable patients for TIL therapy to improve response rate and duration. Overall, the outlook for TIL therapy for melanoma is very bright. We predict that TILs will indeed emerge to become an approved treatment in the upcoming years through pivotal clinical trials. Moreover, new approaches combining TILs with targeted signaling pathway drugs, such as mutant B-RAF inhibitors, and synergistic immunomodulatory interventions enhancing T-cell costimulation and preventing negative regulation should further increase therapeutic efficacy and durable complete response rates.

Granule-derived granzyme B mediates the vulnerability of human neurons to T cell-induced neurotoxicity

Multiple sclerosis (MS) is considered an autoimmune disease of the CNS and is characterized by inflammatory cells infiltrating the CNS and inducing demyelination, axonal loss, and neuronal death. Recent evidence strongly suggests that axonal and neuronal degeneration underlie the progression of permanent disability in MS. In this study, we report that human neurons are selectively susceptible to the serine-protease granzyme B (GrB) isolated from cytotoxic T cell granules. In vitro, purified human GrB induced neuronal death to the same extent as the whole activated T cell population. On the contrary, activated T cells isolated from GrB knockout mice failed to induce neuronal injury. We found that following internalization through various parts of neurons, GrB accumulated in the neuronal soma. Within the cell body, GrB diffused out of endosomes possibly through a perforin-independent mechanism and induced subsequent activation of caspases and cleavage of α-tubulin. Inhibition of caspase-3, a well-known substrate for GrB, significantly reduced GrB-mediated neurotoxicity. We demonstrated that treatment of neurons with mannose-6-phosphate prevented GrB entry and inhibited GrB-mediated neuronal death, suggesting mannose-6-phosphate receptor-dependent endocytosis. Together, our data unveil a novel mechanism by which GrB induces selective neuronal injury and suggest potential new targets for the treatment of inflammatory-mediated neurodegeneration in diseases such as MS.

Perforin enhances the granulysin-induced lysis of Listeria innocua in human dendritic cells

Background

Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells play an essential role in the host defence against intracellular pathogens such as Listeria, and Mycobacteria. The key mediator of bacteria-directed cytotoxicity is granulysin, a 9 kDa protein stored in cytolytic granules together with perforin and granzymes. Granulysin binds to cell membranes and is subsequently taken up via a lipid raft-associated mechanism. In dendritic cells (DC) granulysin is further transferred via early endosomes to L. innocua-containing phagosomes were bacteriolysis is induced. In the present study we analysed the role of perforin in granulysin-induced intracellular bacteriolysis in DC.

Results

We found granulysin-induced lysis of intracellular Listeria significantly increased when perforin was simultaneously present. In pulse-chase experiments enhanced bacteriolysis was observed when perforin was added up to 25 minutes after loading the cells with granulysin demonstrating no ultimate need for simultaneous uptake of granulysin and perforin. The perforin concentration sufficient to enhance granulysin-induced intracellular bacteriolysis did not cause permanent membrane pores in Listeria-challenged DC as shown by dye exclusion test and LDH release. This was in contrast to non challenged DC that were more susceptible to perforin lysis. For Listeria-challenged DC, there was clear evidence for an Ca²⁺ influx in response to sublytic perforin demonstrating a short-lived change in the plasma membrane permeability. Perforin treatment did not affect granulysin binding, initial uptake or intracellular trafficking to early endosomes. However, enhanced colocalization of granulysin with listerial DNA in presence of perforin was found by confocal laser scanning microscopy.

Conclusion

The results provide evidence that perforin increases granulysin-mediated killing of intracellular Listeria by enhanced phagosome-endosome fusion triggered by a transient Ca²⁺ flux.

Exogenous IL-10 overexpression reduces perforin production by activated allogenic CD8+cells and prolongs cardiac allograft survival

Perforin is a cytolytic mediator produced by cytotoxic T cells (CD8+cells) and natural killer cells. We previously reported that ex vivo IL-10 gene therapy induced apoptosis of allogenic infiltrative CD8+cells and significantly prolonged cardiac allograft survival. To further test the hypothesis that localized IL-10 overexpression in cardiac allografts may also effect the alloreactive CD8+T cell function by downregulating its perforin production, we used a rabbit functional heterotopic allograft heart transplant model. Human recombinant IL-10 gene complexed with liposome was intracoronary delivered into the cardiac allografts ex vivo. The percentage of apoptotic infiltrative CD8+cells in cardiac allografts was increased 6-fold in the gene therapy group vs. the control group, whereas the percentage of perforin-positive CD8+cells was decreased 2.9-fold ( P < 0.01). Perforin expression level in the allograft myocardium of the gene therapy group was deceased 3.2-fold ( P < 0.01). The amount of infiltrative perforin-positive CD8+cells and perforin expression level were inversely correlated with IL-10 transgene and protein expression level in the myocardium of cardiac allografts ( P < 0.01), the percentage of apoptotic cardiac myocytes ( P < 0.01), and the peak left ventricular systolic pressure of cardiac allografts ( P < 0.01) but significantly correlated with the infiltrative T cell cytotoxicity ( P < 0.01) and allograft rejection score ( P < 0.01). These results suggest that localized IL-10 gene therapy prolongs cardiac allograft survival, at least in part, through downregulation of perforin production by activated allogenic CD8+T cells. Reduction of cytolytic function of cytotoxic effector cells prevents the apoptosis of cardiac myocytes.

Addressing the mysteries of perforin function

Perforin is a cytolytic protein stored in secretory granules of CTL and NK cells. It synergizes with proapoptotic serine proteases, granzymes, to deliver the lethal hit to virus-infected or transformed target cells. The mechanism of perforin action has not been described beyond its original characterization in the 1980s, and its role in human disease has remained elusive. This article addresses recent key advances in genetic, clinical and biochemical studies that have reignited the current interest in perforin biology.

Isolation and characterization of novel single-chain Fv specific for human granzyme B

Granzyme B, a neutral serine protease, has been demonstrated to be a pivotal molecule for protective immunity against viral infection and cellular malignant transformation. To facilitate monitoring of granzyme B levels, we have recently applied phage display technology to produce single-chain Fv antibodies specific for granzyme B, as versatile alternatives and complementary reagents to currently available monoclonal antibodies. Through four rounds of panning on purified human granzyme B-coated on solid phase, three unique clones were isolated. Expressed soluble scFv antibodies demonstrated specific immunological applications including ELISA, Western blotting, immunoprecipitation and intracellular staining. Based on sequence analyses and structural modeling, one scFv, Fv17, may have overlapping antigen binding specificity with monoclonal antibodies 2C5/F5 and GB11. Owing to the availability of its DNA sequence and large scale production capability, Fv17 should be a superior reagent for monitoring granzyme B expression in natural killer cells and antigen specific CD8+ T cell immunity.

Increase in granzyme B+ lymphocytes and soluble granzyme B in bronchoalveolar lavage of allergen challenged patients with atopic asthma

Asthma has been linked to a chronic, T-cell-mediated bronchial inflammation. Because other T-lymphocyte-mediated, chronic inflammatory disorders have been associated with elevated granzyme B (grB) expression we tested the hypothesis that atopic asthma might be associated with elevated grB levels in the bronchoalveolar compartment. Therefore we performed intracellular grB staining in lymphocytes from bronchoalveolar lavage (BAL) collected 42 h after segmental allergen provocation (SAP) in allergic patients with bronchial asthma. There was a significant increase in CD3(+), CD8(+), and CD16/56(+) lymphocytes expressing grB in BAL 42 h after SAP as compared to saline challenged controls. However, compared to peripheral blood the percentages of these lymphocyte subsets detected as grB(+) in BAL remained significantly lower. Measurement of extracellular grB in BAL fluids by a particle immunoassay revealed significantly elevated grB levels in the allergen challenged bronchoalveolar compartment 42 h following SAP in six of the eight patients (range, <1.0-348.1 pg/ml) as compared to saline challenged controls (range, <1.0-70.5 pg/ml). We conclude that total cell numbers of grB(+) lymphocyte subsets increase 42 h after SAP in the lower respiratory tract. In addition there is evidence to suggest that grB is released into the airways of asthmatic patients. This suggests a role for grB in the pathophysiological processes following SAP but its definitive role in allergic bronchial asthma needs to be established.

Direct cleavage of the human DNA fragmentation factor-45 by granzyme B induces caspase-activated DNase release and DNA fragmentation

The protease granzyme B (GrB) plays a key role in the cytocidal activity during cytotoxic T lymphocyte (CTL)-mediated programmed cell death. Multiple caspases have been identified as direct substrates for GrB, suggesting that the activation of caspases constitutes an important event during CTL-induced cell death. However, recent studies have provided evidence for caspase-independent pathway(s) during CTL-mediated apoptosis. In this study, we demonstrate caspase-independent and direct cleavage of the 45 kDa unit of DNA fragmentation factor (DFF45) by GrB both in vitro and in vivo. Using a novel and selective caspase-3 inhibitor, we show the ability of GrB to process DFF45 directly and mediate DNA fragmentation in the absence of caspase-3 activity. Furthermore, studies with DFF45 mutants reveal that both caspase-3 and GrB share a common cleavage site, which is necessary and sufficient to induce DNA fragmentation in target cells during apoptosis. Together, our data suggest that CTLs possess alternative mechanism(s) for inducing DNA fragmentation without the requirement for caspases.

A comparative study of the expression of cytotoxic proteins in allergic contact dermatitis and psoriasis: spongiotic skin lesions in allergic contact dermatitis are highly infiltrated by T cells expressing perforin and granzyme B

Recent reports indicate that cytotoxic T cells are critically involved in contact hypersensitivity reactions in animals. In this study we sought to investigate the in vivo expression of cytotoxic granule proteins in the elicitation phase of allergic contact dermatitis in humans. Skin biopsy specimens were obtained from patients with allergic contact dermatitis (n = 8) and psoriasis (n = 6) and from controls with normal skin (n = 6). Expression of perforin and granzyme B was investigated by in situ hybridization and immunohistochemistry. In contrast to normal skin and psoriasis, a significant enhancement of perforin and granzyme B gene expression and immunoreactivity was observed in the mononuclear cell infiltrate of allergic contact dermatitis. Immunoreactivity for perforin and granzyme B was mainly found in the cytoplasm of lymphocytic cells, which were located in the dense perivascular infiltrate as well as at sites of marked spongiosis in the epidermis. Double immunostaining revealed that both CD4+ and CD8+ T cells are capable of expressing perforin and granzyme B. In conclusion, our data suggest that T-cell-mediated mechanisms involving cytotoxic granule proteins may elicit epidermal cell injury in vivo and thereby strongly contribute to the development of allergic contact dermatitis in humans.

Infiltration of cytotoxic T cells in drug-induced cutaneous eruptions

BACKGROUND

Previous in vitro data indicate that perforin containing drug-specific cytotoxic T cells are involved in cutaneous drug reactions.

OBJECTIVE

The aim of this study was to investigate the in situ expression of perforin and granzyme B together with the nature of the inflammatory infiltrate in acute drug-induced exanthem. Furthermore, expression of interleukin (IL)-12 and interferon (IFN)-gamma, which are known to stimulate cytotoxic T cells, was investigated.

METHODS

Skin biopsy specimens were obtained from 10 patients with a generalized maculopapular exanthem and from nine controls with normal skin. Expression of CD3, CD4, CD8, CD56, CD1a, CD68, CD25, HLA-DR, CD54, perforin, granzyme B, IL-12 and IFNgamma was analysed using immunohistochemistry.

RESULTS

In contrast to the controls, the skin of patients with an exanthem was mainly infiltrated by T cells (CD4 > CD8) and showed a marked enhancement of perforin and granzyme B immunostaining. Double immunostaining revealed that perforin and granzyme B were expressed in both CD4+ and CD8+ cells, which were partly located at the dermoepidermal junction and in the epidermis. In addition, strong immunreactivity for IL-12 and IFNgamma was observed in the mononuclear cells infiltrate, indicating that these cytokines may be important in activation of these cytotoxic T cells.

CONCLUSION

The increased numbers of perforin and granzyme B containing T cells infiltrating the dermoepidermal junction may contribute to the damage of epidermal cells, which is frequently observed as a typical feature of interface dermatitis in drug-induced exanthem. Our data provide further evidence that cytotoxic T cells play an essential role in cutaneous drug reactions.

Granzymes (lymphocyte serine proteases): characterization with natural and synthetic substrates and inhibitors

Natural killer (NK) and cytotoxic T-lymphocytes (CTLs) kill cells within an organism to defend it against viral infections and the growth of tumors. One mechanism of killing involves exocytosis of lymphocyte granules which causes pores to form in the membranes of the attacked cells, fragments nuclear DNA and leads to cell death. The cytotoxic granules contain perforin, a pore-forming protein, and a family of at least 11 serine proteases termed granzymes. Both perforin and granzymes are involved in the lytic activity. Although the biological functions of most granzymes remain to be resolved, granzyme B clearly promotes DNA fragmentation and is directly involved in cell death. Potential natural substrates for Gr B include procaspases and other proteins involved in cell death. Activated caspases are involved in apoptosis. The search continues for natural substrates for the other granzymes. The first granzyme crystal structure remains to be resolved, but in the interim, molecular models of granzymes have provided valuable structural information about their substrate binding sites. The information has been useful to predict the amino acid sequences that immediately flank each side of the scissile peptide bond of peptide and protein substrates. Synthetic substrates, such as peptide thioesters, nitroanilides and aminomethylcoumarins, have also been used to study the substrate specificity of granzymes. The different granzymes have one of four primary substrate specificities: tryptase (cleaving after Arg or Lys), Asp-ase (cleaving after Asp), Met-ase (cleaving after Met or Leu), and chymase (cleaving after Phe, Tyr, or Trp). Natural serpins and synthetic inhibitors (including isocoumarins, peptide chloromethyl ketones, and peptide phosphonates) inhibit granzymes. Studies of substrate and inhibitor kinetics are providing valuable information to identify the most likely natural granzyme substrates and provide tools for the study of key reactions in the cytolytic mechanism.

Perforin-dependent nuclear targeting of granzymes: A central role in the nuclear events of granule-exocytosis-mediated apoptosis?

Programmed cell death, apoptosis, involves very distinctive changes within the target cell nucleus, including margination of the chromatin, DNA fragmentation and breakdown of the nuclear envelope. Cytolytic granule-mediated target cell apoptosis is effected, in part, through synergistic action of the membrane-acting protein perforin and serine proteases, such as granzymes A or B. Recent work using confocal laser scanning microscopy as well as other techniques supports the idea that perforin-dependent translocation of granzymes to the nucleus of target cells plays a central role in effecting the nuclear changes associated with apoptosis. In vitro experiments indicate that granzyme nuclear import follows a novel pathway, being independent of ATP, not inhibitable by non-hydrolysable GTP analogues and involving binding within the nucleus, unlike conventional signal- dependent nuclear protein import. In intact cells, perforin-dependent nuclear entry of granzymes precedes the nuclear events of apoptosis such as DNA fragmentation and nuclear envelope breakdown; prevention of granzyme nuclear translocation through bcl2 overexpression or treatment of target cells with inhibitors of caspase activation blocks these events. Nuclear localization of granzymes thus appears to be central to induction of the nuclear changes associated with cytolytic granule-mediated apoptosis.

Exercise and cellular innate immune function

Epidemiological evidence suggests a link between the intensity of exercise and infectious and neoplastic disease. One likely way by which exercise exerts its effect on cancer and infection is by altering the function of the immune system. Cells of the innate immune system (i.e., macrophage [Mphi], natural killer [NK] cell, and polymorphonuclear neutrophils [PMN]) are first-line defenders against cancer and infectious disease by nature of their phagocytic, cytolytic, and antimicrobial properties. The purpose of this review is to define the role of cells of the innate immune system (i.e., Mphi, PMN, and NK cells) in infection and cancer, present current information regarding the effects of acute and chronic exercise on the quantification and functional activities of these cells, and briefly to discuss potential mechanisms as to how exercise affects these cells and describe how these changes may potentially affect susceptibility to infection and cancer. The effects of exercise on the number, functions, and characteristics of cells of the innate immune system are complex and are dependent several factors, including 1) the cell function or characteristic being analyzed; 2) the intensity, duration and chronicity of exercise; 3) the timing of measurement in relation to the exercise bout; 4) the dose and type of immunomodulator used to stimulate the cell in vitro or in vivo; and 5) the site of cellular origin. Further studies are needed to determine whether the exercise-induced changes in immune function alter incidence or progression of disease. Likewise, the mechanisms as to how exercise alters innate immune function are as yet unresolved.