Reactive oxygen species involved in CT26 immunogenic cell death induced by Clostridium difficile toxin B

Copper-Induced Supramolecular Peptide Assemblies for Multi-Pathway Cell Death and Tumor Inhibition

Although self-assembly has emerged as an effective tool for fabricating biomaterials, achieving precise control over the morphologies and functionalities of the resultant assemblies remains an ongoing challenge. Inspired by the copper peptide naturally present in human plasma, in this study, we designed a synthetic precursor, FcGH. FcGH can self-assemble via two distinct pathways: spontaneous and Cu2+-induced. These two assembly pathways enabled the formation of assemblies with tunable morphologies by adjusting the amount of added Cu2+. We found that the nanoparticles formed by Cu2+-induced self-assembly exhibited a significantly higher cellular uptake efficiency than the wormlike fibers formed spontaneously. Moreover, this Cu2+-induced assembly process occurred spontaneously at a 1 : 1 molar ratio of Cu2+ to FcGH, avoiding the excessive use of Cu2+ and a tedious preparation procedure. By co-assembling with 10-hydroxycamptothecin (HCPT)-conjugated FcGH, Cu2+-induced supramolecular nanodrugs elicited multiple cell death modalities in cancer cells with elevated immunogenicity, enhancing the therapeutic effect compared to free HCPT. This study highlights Cu2+-induced self-assembly as an efficient tool for directing the assembly of nanodrugs and for synergistic tumor therapy.

Surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) in label-free characterization of erythrocyte membranes and extracellular vesicles at the nano-scale and molecular level

The manuscript presents the potential of surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) for label-free characterization of extracellular microvesicles (EVs) and their isolated membranes derived from red blood cells (RBCs) at the nanoscale and at the single-molecule level, providing detection of a few individual amino acids, protein and lipid membrane compartments. The study shows future directions for research, such as investigating the use of the mentioned techniques for the detection and diagnosis of diseases. We demonstrate that SERS and TERS are powerful techniques for identifying the biochemical composition of EVs and their membranes, allowing the detection of small molecules, lipids, and proteins. Furthermore, extracellular vesicles released from red blood cells (REVs) can be broadly classified into exosomes, microvesicles, and apoptotic bodies, based on their size and biogenesis pathways. Our study specifically focuses on microvesicles that range from 100 to 1000 nanometres in diameter, as presented in AFM images. Using SERS and TERS spectra obtained for REVs and their membranes, we were able to characterize the chemical and structural properties of microvesicle membranes with high sensitivity and specificity. This information may help better distinguish and categorize different types of EVs, leading to a better understanding of their functions and potential biomedical applications.

Immunogenic cell death (ICD)-inducers in non-small-cell lung carcinoma (NSCLC): current knowledge and future perspective

The prevalence of non-small-cell lung cancer (NSCLC) is rising every year all around the world. The interaction between cancer cells and the tumor microenvironment (TME) is a crucial factor in determining the development of human neoplasms. Organellar and cellular stress are induced during immunogenic cell death (ICD), a particularly functional response pattern. ICD is a separate but poorly characterized entity caused by various cancer treatments. The induction of ICD has the potential to change TME and the recruitment of tumor-infiltrating lymphocytes (TILs), and the coupling of ICD-inducers and other therapeutic approaches can have a synergistic role in boosting anticancer impacts. The purpose of this study is to review the studies in the field of NSCLC using ICD-inducers as a treatment strategy or as a combination therapy. This review provide for researches a better view of what has been done so far and the challenges they face in the future.

The Evolution and Future of Targeted Cancer Therapy: From Nanoparticles, Oncolytic Viruses, and Oncolytic Bacteria to the Treatment of Solid Tumors

While many classes of chemotherapeutic agents exist to treat solid tumors, few can generate a lasting response without substantial off-target toxicity despite significant scientific advancements and investments. In this review, the paths of development for nanoparticles, oncolytic viruses, and oncolytic bacteria over the last 20 years of research towards clinical translation and acceptance as novel cancer therapeutics are compared. Novel nanoparticle, oncolytic virus, and oncolytic bacteria therapies all start with a common goal of accomplishing therapeutic drug activity or delivery to a specific site while avoiding off-target effects, with overlapping methodology between all three modalities. Indeed, the degree of overlap is substantial enough that breakthroughs in one therapeutic could have considerable implications on the progression of the other two. Each oncotherapeutic modality has accomplished clinical translation, successfully overcoming the potential pitfalls promising therapeutics face. However, once studies enter clinical trials, the data all but disappears, leaving pre-clinical researchers largely in the dark. Overall, the creativity, flexibility, and innovation of these modalities for solid tumor treatments are greatly encouraging, and usher in a new age of pharmaceutical development.

Alternol triggers immunogenic cell death via reactive oxygen species generation

Alternol is a naturally occurring compound that exerts antitumor activity in several cancers. However, whether Alternol induces antitumor immune response remains unknown. In this study, we investigated whether Alternol induced immunogenic cell death (ICD) in prostate cancer cells. Alternol triggered ICD in prostate cancer cells, as evidenced by the release of damage-associated molecular patterns (DAMPs) (i.e., calreticulin, CALR; high mobility group protein B1, HMGB1; and adenosine triphosphate, ATP) and pro-inflammatory cytokine (i.e., interleukin [IL]-1α, IL-1β, IL-6, and IL-8) expression. Alternol facilitated tumor-associated antigen uptake and cross-presentation, CD8 + T-cell priming, and T-cell infiltration in tumor-draining lymph nodes (LNs) and tumors. The presence of Alternol fostered antitumor immune response in vivo, resulting in delayed tumor growth and prolonged survival. Moreover, inhibition of reactive oxygen species (ROS) generation blocked Alternol-induced upregulation of pre-inflammation cytokines, endoplasmic reticulum (ER) stress, and consequent antitumor immune response. Overall, our data indicate that Alternol triggers ICD in prostate cancer cells, which is mediated by ROS generation.

Genetically engineered oncolytic bacteria as drug delivery systems for targeted cancer theranostics

Drug delivery systems based on genetically engineered oncolytic bacteria have properties that cannot be achieved by traditional therapeutic interventions. Thus, they have attracted considerable attention in cancer therapies. Attenuated bacteria can specifically target and actively penetrate tumor tissues and play an important role in cancer suppression as the "factories" of diverse anticancer drugs. Over the past decades, several bacterial strains including Salmonella and Clostridium have been shown to effectively retard tumor growth and metastasis, and thus improve survival in preclinical models or clinical cases. In this review, we summarize the unique properties of oncolytic bacteria and their anticancer mechanisms and highlight the particular advantages compared with traditional strategies. With the current research progress, we demonstrate the potential value of oncolytic bacteria-based drug delivery systems for clinical applications. In addition, we discuss novel strategies of cancer therapies integrating oncolytic bacteria, which will provide hope to further improve and standardize the current regimens in the near future.

Detection of immunogenic cell death and its relevance for cancer therapy

Chemotherapy, radiation therapy, as well as targeted anticancer agents can induce clinically relevant tumor-targeting immune responses, which critically rely on the antigenicity of malignant cells and their capacity to generate adjuvant signals. In particular, immunogenic cell death (ICD) is accompanied by the exposure and release of numerous damage-associated molecular patterns (DAMPs), which altogether confer a robust adjuvanticity to dying cancer cells, as they favor the recruitment and activation of antigen-presenting cells. ICD-associated DAMPs include surface-exposed calreticulin (CALR) as well as secreted ATP, annexin A1 (ANXA1), type I interferon, and high-mobility group box 1 (HMGB1). Additional hallmarks of ICD encompass the phosphorylation of eukaryotic translation initiation factor 2 subunit-α (EIF2S1, better known as eIF2α), the activation of autophagy, and a global arrest in transcription and translation. Here, we outline methodological approaches for measuring ICD markers in vitro and ex vivo for the discovery of next-generation antineoplastic agents, the development of personalized anticancer regimens, and the identification of optimal therapeutic combinations for the clinical management of cancer.

Nonthermal plasma as part of a novel strategy for vaccination

Vaccination has been one of the most effective health intervention mechanisms to reduce morbidity and mortality associated with infectious diseases. Vaccines stimulate the body's protective immune responses through controlled exposure to modified versions of pathogens that establish immunological memory. However, only a few diseases have effective vaccines. The biological effects of nonthermal plasma on cells suggest that plasma could play an important role in improving efficacy of existing vaccines and overcoming some of the limitations and challenges with current vaccination strategies. This review summarizes the opportunities for nonthermal plasma for immunization and therapeutic purposes.

Immunostimulation with chemotherapy in the era of immune checkpoint inhibitors

Conventional chemotherapeutics have been developed into clinically useful agents based on their ability to preferentially kill malignant cells, generally owing to their elevated proliferation rate. Nonetheless, the clinical activity of various chemotherapies is now known to involve the stimulation of anticancer immunity either by initiating the release of immunostimulatory molecules from dying cancer cells or by mediating off-target effects on immune cell populations. Understanding the precise immunological mechanisms that underlie the efficacy of chemotherapy has the potential not only to enable the identification of superior biomarkers of response but also to accelerate the development of synergistic combination regimens that enhance the clinical effectiveness of immune checkpoint inhibitors (ICIs) relative to their effectiveness as monotherapies. Indeed, accumulating evidence supports the clinical value of combining appropriately dosed chemotherapies with ICIs. In this Review, we discuss preclinical and clinical data on the immunostimulatory effects of conventional chemotherapeutics in the context of ICI-based immunotherapy.

Current Approaches for Combination Therapy of Cancer: The Role of Immunogenic Cell Death

Cell death resistance is a key feature of tumor cells. One of the main anticancer therapies is increasing the susceptibility of cells to death. Cancer cells have developed a capability of tumor immune escape. Hence, restoring the immunogenicity of cancer cells can be suggested as an effective approach against cancer. Accumulating evidence proposes that several anticancer agents provoke the release of danger-associated molecular patterns (DAMPs) that are determinants of immunogenicity and stimulate immunogenic cell death (ICD). It has been suggested that ICD inducers are two different types according to their various activities. Here, we review the well-characterized DAMPs and focus on the different types of ICD inducers and recent combination therapies that can augment the immunogenicity of cancer cells.

The Destruction Of Laser-Induced Phase-Transition Nanoparticles Triggered By Low-Intensity Ultrasound: An Innovative Modality To Enhance The Immunological Treatment Of Ovarian Cancer Cells

Purpose

Photodynamic therapy (PDT), sonodynamic therapy (SDT), and oxaliplatin (OXP) can induce immunogenic cell death (ICD) following damage-associated molecular patterns (DAMPs) exposure or release and can be united via the use of nanoplatforms to deliver drugs that can impart anti-tumor effects. The aim of this study was to develop phase-transition nanoparticles (OI_NPs) loaded with perfluoropentane (PFP), indocyanine green (ICG), and oxaliplatin (OXP), to augment anti-tumor efficacy and the immunological effects of chemotherapy, photodynamic therapy and sonodynamic therapy (PSDT).

Methods

OI_NPs were fabricated by a double emulsion method and a range of physicochemical and dual-modal imaging features were characterized. Confocal microscopy and flow cytometry were used to determine the cellular uptake of OI_NPs by ID8 cells. The viability and apoptotic rate of ID8 cells were investigated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry. Flow cytometry, Western blotting, and luminometric assays were then used to investigate the exposure or release of crucial DAMPs such as calreticulin (CRT), high mobility group box 1 (HMGB1), and adenosine-5ʹ-triphosphate (ATP). Tumor rechallenge experiments were then used to investigate whether treated ID8 cells underwent ICD. Finally, cytotoxic T lymphocyte (CTL) activity was determined by a lactate dehydrogenase (LDH) assay.

Results

Spherical OI_NPs were able to carry OXP, ICG and PFP and were successfully internalized by ID8 cells. The application of OI_NPs significantly enhanced the phase shift ability of PFP and the optical characteristics of ICG, thus leading to a significant improvement in photoacoustic and ultrasonic imaging. When combined with near-infrared light and ultrasound, the application of OI_NPs led to improved anti-tumor effects on cancer cells, and significantly enhanced the expression of DAMPs, thus generating a long-term anti-tumor effect.

Conclusion

The application of OI_NPs, loaded with appropriate cargo, may represent a novel strategy with which to increase anti-tumor effects, enhance immunological potency, and improve dual-mode imaging.

Intrinsic cancer vaccination

Immunotherapy is revolutionizing the treatment of cancer, and the current immunotherapeutics have remarkably improved the outcomes for some cancer patients. However, we still need answers for patients with immunologically cold tumors that do not benefit from the current immunotherapy treatments. Here, we suggest a novel strategy that is based on using a very old and sophisticated system for cancer immunotherapy, namely "intrinsic cancer vaccination", which seeks to awaken our own immune system to activate tumor-specific T cells. To do this, we must take advantage of the genetic instability of cancer cells and the expression of cancer cell neoantigens to trigger immunity against cancer cells. It will be necessary to not only enhance the phagocytosis of cancer cells by antigen presenting cells but also induce immunogenic cancer cell death and the subsequent immunogenic clearance, cross-priming and generation of tumor-specific T cells. This strategy will allow us to avoid using known tumor-specific antigens, ex vivo manipulation or adoptive cell therapy; rather, we will efficiently present cancer cell neoantigens to our immune system and propagate the cancer-immunity cycle. This strategy simply follows the natural cycle of cancer-immunity from its very first step, and therefore could be combined with any other treatment modality to yield enhanced efficacy.

Plasma-activated medium triggers cell death and the presentation of immune activating danger signals in melanoma and pancreatic cancer cells

Over the past decade, cold atmospheric plasmas have shown promising application in cancer therapy. The therapeutic use of plasma-activated media is a topic addressed in an emerging field known as plasma pharmacy. In oncology, plasma-activated media are  used to harness the therapeutic effects of oxidant species when they come in contact with cancer cells. Among several factors that contribute to the anticancer effect of plasma-activated liquid media (PALM), H₂O₂ and NO derivatives likely play a key role in the apoptotic pathway. Despite the significant amount of literature produced in recent years, a full understanding of the mechanisms by which PALM exert their activity against cancer cells is limited. In this paper, a sealed dielectric-barrier discharge was used to disentangle the effect of reactive nitrogen species (RNS) from that of reactive oxygen species (ROS) on cancer cells. Two cancers characterized by poor prognosis have been investigated: metastatic melanoma and pancreatic cancer. Both tumour models exposed to PALM rich in H₂O₂ showed a reduction in proliferation and an increase in calreticulin exposure and ATP release, suggesting the potential use of activated media as an inducer of immunogenic cell death via activation of the innate immune system.

Nanosecond-Pulsed DBD Plasma-Generated Reactive Oxygen Species Trigger Immunogenic Cell Death in A549 Lung Carcinoma Cells through Intracellular Oxidative Stress

A novel application for non-thermal plasma is the induction of immunogenic cancer cell death for cancer immunotherapy. Cells undergoing immunogenic death emit danger signals which facilitate anti-tumor immune responses. Although pathways leading to immunogenic cell death are not fully understood; oxidative stress is considered to be part of the underlying mechanism. Here; we studied the interaction between dielectric barrier discharge plasma and cancer cells for oxidative stress-mediated immunogenic cell death. We assessed changes to the intracellular oxidative environment after plasma treatment and correlated it to emission of two danger signals: surface-exposed calreticulin and secreted adenosine triphosphate. Plasma-generated reactive oxygen and charged species were recognized as the major effectors of immunogenic cell death. Chemical attenuators of intracellular reactive oxygen species successfully abrogated oxidative stress following plasma treatment and modulated the emission of surface-exposed calreticulin. Secreted danger signals from cells undergoing immunogenic death enhanced the anti-tumor activity of macrophages. This study demonstrated that plasma triggers immunogenic cell death through oxidative stress pathways and highlights its potential development for cancer immunotherapy.

Salubrinal protects against Clostridium difficile toxin B-induced CT26 cell death

Clostridium difficile (C. difficile) is considered to be the major cause of the antibiotic-associated diarrhea and pseudomembranous colitis in animals and humans. The prevalence of C. difficile infections (CDI) has been increasing since 2000. Two exotoxins of C. difficile, Toxin A (TcdA) and Toxin B (TcdB), are the main virulence factors of CDI, which can induce glucosylation of Rho GTPases in host cytosol, leading to cell morphological changes, cell apoptosis, and cell death. The mechanism of TcdB-induced cell death has been investigated for decades, but it is still not completely understood. It has been reported that TcdB induces endoplasmic reticulum stress via PERK-eIF2α signaling pathway in CT26 cell line (BALB/C mouse colon tumor cells). In this study, we found that salubrinal, a selective inhibitor of eIF2α dephosphorylation, efficiently protects CT26 cell line against TcdB-induced cell death and tried to explore the mechanism underlying in this protective effect. Our results demonstrated that salubrinal protects CT26 cells from TcdB-mediated cytotoxic and cytopathic effect, inhibits apoptosis and death of the toxin-exposed cells via caspase-9-dependent pathway, eIF2α signaling pathway, and autophagy. These findings will be helpful for the development of CDI therapies.

The oncolytic peptide LTX-315 induces cell death and DAMP release by mitochondria distortion in human melanoma cells

Host defense peptides (HDPs) are naturally occurring molecules found in most species, in which they play a significant role in the first line defense against intruding pathogens, and several HDPs have been shown to possess anticancer activity. Structure-activity relationship studies on the HDP bovine lactoferricin revealed a de novo design of a nonamer peptide LTX-315, with oncolytic properties. In the present study, we investigated the oncolytic activity of LTX-315 in human melanoma cells (A375). LTX-315 induced a rapid plasma membrane disruption and cell death within 2 hours. At a low concentration, fluorescence-labeled LTX-315 was internalized and accumulated in cytoplasmic vacuoles in close proximity to the mitochondria. The mitochondrial membrane potential was shown to depolarize as a consequence of LTX-315 treatment and at ultrastructural level, the mitochondria morphology was significantly altered. Release of danger signals (DAMPs) such as ATP, Cytochrome C and HMGB1 into the cell supernatant of cultured cells was evident minutes after peptide treatment. The oncolytic effect of LTX-315 involving perturbation of both the cell membrane and the mitochondria with subsequent release of DAMPs may highlight the ability of LTX-315 to induce complete regression and long-term protective immune responses as previously reported in experimental animal models.

Reactive Oxygen Species as Additional Determinants for Cytotoxicity of Clostridium difficile Toxins A and B

Clostridium difficile infections can induce mild to severe diarrhoea and the often associated characteristic pseudomembranous colitis. Two protein toxins, the large glucosyltransferases TcdA and TcdB, are the main pathogenicity factors that can induce all clinical symptoms in animal models. The classical molecular mode of action of these homologous toxins is the inhibition of Rho GTPases by mono-glucosylation. Rho-inhibition leads to breakdown of the actin cytoskeleton, induces stress-activated and pro-inflammatory signaling and eventually results in apoptosis of the affected cells. An increasing number of reports, however, have documented further qualities of TcdA and TcdB, including the production of reactive oxygen species (ROS) by target cells. This review summarizes observations dealing with the production of ROS induced by TcdA and TcdB, dissects pathways that contribute to this phenomenon and speculates about ROS in mediating pathogenesis. In conclusion, ROS have to be considered as a discrete, glucosyltransferase-independent quality of at least TcdB, triggered by different mechanisms.

Molecular and Translational Classifications of DAMPs in Immunogenic Cell Death

The immunogenicity of malignant cells has recently been acknowledged as a critical determinant of efficacy in cancer therapy. Thus, besides developing direct immunostimulatory regimens, including dendritic cell-based vaccines, checkpoint-blocking therapies, and adoptive T-cell transfer, researchers have started to focus on the overall immunobiology of neoplastic cells. It is now clear that cancer cells can succumb to some anticancer therapies by undergoing a peculiar form of cell death that is characterized by an increased immunogenic potential, owing to the emission of the so-called “damage-associated molecular patterns” (DAMPs). The emission of DAMPs and other immunostimulatory factors by cells succumbing to immunogenic cell death (ICD) favors the establishment of a productive interface with the immune system. This results in the elicitation of tumor-targeting immune responses associated with the elimination of residual, treatment-resistant cancer cells, as well as with the establishment of immunological memory. Although ICD has been characterized with increased precision since its discovery, several questions remain to be addressed. Here, we summarize and tabulate the main molecular, immunological, preclinical, and clinical aspects of ICD, in an attempt to capture the essence of this phenomenon, and identify future challenges for this rapidly expanding field of investigation.