Small-molecule toosendanin reverses macrophage-mediated immunosuppression to overcome glioblastoma resistance to immunotherapy

Strategies to overcome tumor microenvironment immunosuppressive effect on the functioning of CAR-T cells in high-grade glioma

Despite significant progress in the treatment of some types of cancer, high-grade gliomas (HGGs) remain a significant clinical problem. In the case of glioblastoma (GBM), the most common solid tumor of the central nervous system in adults, the average survival time from diagnosis is only 15-18 months, despite the use of intensive multimodal therapy. Chimeric antigen receptor (CAR)-expressing T cells, which have already been approved by the Food and Drug Administration for use in the treatment of certain hematologic malignancies, are a new, promising therapeutic option. However, the efficacy of CAR-T cells in solid tumors is lower due to the immunosuppressive tumor microenvironment (TME). Reprogramming the immunosuppressive TME toward a pro-inflammatory phenotype therefore seems particularly important because it may allow for increasing the effectiveness of CAR-T cells in the therapy of solid tumors. The following literature review aims to present the results of preclinical studies showing the possibilities of improving the efficacy of CAR-T in the TME of GBM by reprogramming the TME toward a pro-inflammatory phenotype. It may be achievable thanks to the use of CAR-T in a synergistic therapy in combination with oncolytic viruses, radiotherapy, or epigenetic inhibitors, as well as by supporting CAR-T cells crossing of the blood-brain barrier, normalizing impaired angiogenesis in the TME, improving CAR-T effector functions by cytokine signaling or by blocking/knocking out T-cell inhibitors, and modulating the microRNA expression. The use of CAR-T cells modified in this way in synergistic therapy could lead to the longer survival of patients with HGG by inducing an endogenous anti-tumor response.

Rosmarinic acid alleviates toosendanin-induced liver injury through restoration of autophagic flux and lysosomal function by activating JAK2/STAT3/CTSC pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Rosmarinic acid (RA), a natural polyphenol abundant in numerous herbal remedies, has been attracting growing interest owing to its exceptional ability to protect the liver. Toosendanin (TSN), a prominent bioactive compound derived from Melia toosendan Siebold & Zucc., boasts diverse pharmacological properties. Nevertheless, TSN possesses remarkable hepatotoxicity. Intriguingly, the potential of RA to counteract TSN-induced liver damage and its probable mechanisms remain unexplored.

AIM OF THE STUDY

This study is aimed at exploring whether RA can alleviate TSN-induced liver injury and the potential mechanisms involved autophagy.

MATERIALS AND METHODS

CCK-8 and LDH leakage rate assay were used to evaluate cytotoxicity. Balb/c mice were intraperitoneally administered TSN (20 mg/kg) for 24 h after pretreatment with RA (0, 40, 80 mg/kg) by gavage for 5 days. The autophagic proteins P62 and LC3B expressions were detected using western blot and immunohistochemistry. RFP-GFP-LC3B and transmission electron microscopy were applied to observe the accumulation levels of autophagosomes and autolysosomes. LysoTracker Red and DQ-BSA staining were used to evaluate the lysosomal acidity and degradation ability respectively. Western blot, immunohistochemistry and immunofluorescence staining were employed to measure the expressions of JAK2/STAT3/CTSC pathway proteins. Dual-luciferase reporter gene was used to measure the transcriptional activity of CTSC and RT-PCR was used to detect its mRNA level. H&E staining and serum biochemical assay were employed to determine the degree of damage to the liver.

RESULTS

TSN-induced damage to hepatocytes and livers was significantly alleviated by RA. RA markedly diminished the autophagic flux blockade and lysosomal dysfunction caused by TSN. Mechanically, RA alleviated TSN-induced down-regulation of CTSC by activating JAK2/STAT3 signaling pathway.

CONCLUSION

RA could protect against TSN-induced liver injury by activating the JAK2/STAT3/CTSC pathway-mediated autophagy and lysosomal function.

T cell exhaustion in human cancers

T cell exhaustion refers to a progressive state in which T cells become functionally impaired due to sustained antigenic stimulation, which is characterized by increased expression of immune inhibitory receptors, but weakened effector functions, reduced self-renewal capacity, altered epigenetics, transcriptional programme and metabolism. T cell exhaustion is one of the major causes leading to immune escape of cancer, creating an environment that supports tumor development and metastatic spread. In addition, T cell exhaustion plays a pivotal role to the efficacy of current immunotherapies for cancer. This review aims to provide a comprehensive view of roles of T cell exhaustion in cancer development and progression. We summerized the regulatory mechanisms that involved in T cell exhaustion, including transcription factors, epigenetic and metabolic reprogramming events, and various microenvironmental factors such as cytokines, microorganisms, and tumor autocrine substances. The paper also discussed the challenges posed by T cell exhaustion to cancer immunotherapies, including immune checkpoint blockade (ICB) therapies and chimeric antigen receptor T cell (CAR-T) therapy, highlightsing the obstacles encountered in ICB therapies and CAR-T therapies due to T cell exhaustion. Finally, the article provides an overview of current therapeutic options aimed to reversing or alleviating T cell exhaustion in ICB and CAR-T therapies. These therapeutic approaches seek to overcome T cell exhaustion and enhance the effectiveness of immunotherapies in treating tumors.

Toosendanin inhibits T-cell proliferation through the P38 MAPK signalling pathway

In recent years, immunosuppressants have shown significant success in the treatment of autoimmune diseases. Therefore, there is an urgent need to develop additional immunosuppressants that offer more options for patients. Toosendanin has been shown to have immunosuppressive activity in vitro as well as effects on autoimmune hepatitis (AIH) in vivo. Toosendanin did not induce apoptosis in activated T-cells and affect the survival rate of naive T-cells. Toosendanin did not affect the expression of CD25 or secretion of IL-2 by activated T-cells, and not affect the expression of IL-4 and INF-γ. Toosendanin did not affect the phosphorylation of STAT5, ERK, AKT, P70S6K. However, toosendanin inhibited proliferation of anti-CD3/anti-CD28 mAbs-activated T-cells with IC50 of (10 ± 2.02) nM. Toosendanin arrested the cell cycle in the G0/G1 phase, significantly inhibited IL-6 and IL-17A secretion, promoted IL-10 expression, and inhibited the P38 MAPK pathway. Finally, toosendanin significantly alleviated ConA-induced AIH in mice. In Summary, toosendanin exhibited immunosuppressive activity in vivo and in vitro. Toosendanin inhibits the proliferation of activated T-cells through the P38 MAPK signalling pathway, significantly suppresses the expression of inflammatory factors, enhances the expression of anti-inflammatory factors, and effectively alleviates ConA-induced AIH in mice, suggesting that toosendanin may be a lead compound for the development of novel immunomodulatory agents with improved efficacy and reduced toxicity.

Accelerating multiplexed profiling of protein-ligand interactions: High-throughput plate-based reactive cysteine profiling with minimal input

Chemoproteomics has made significant progress in investigating small-molecule-protein interactions. However, the proteome-wide profiling of cysteine ligandability remains challenging to adapt for high-throughput applications, primarily due to a lack of platforms capable of achieving the desired depth using low input in 96- or 384-well plates. Here, we introduce a revamped, plate-based platform which enables routine interrogation of either ∼18,000 or ∼24,000 reactive cysteines based on starting amounts of 10 or 20 μg, respectively. This represents a 5-10X reduction in input and 2-3X improved coverage. We applied the platform to screen 192 electrophiles in the native HEK293T proteome, mapping the ligandability of 38,450 reactive cysteines from 8,274 human proteins. We further applied the platform to characterize new cellular targets of established drugs, uncovering that ARS-1620, a KRASG12C inhibitor, binds to and inhibits an off-target adenosine kinase ADK. The platform represents a major step forward to high-throughput proteome-wide evaluation of reactive cysteines.

Protocol to generate traceable CAR T cells for syngeneic mouse cancer models

The efficacy of chimeric antigen receptor (CAR) T cell immunotherapy is limited by insufficient infiltration and activation of T cells due to the immunosuppressive tumor microenvironment. Preclinical studies with optimized mouse CAR T cells in immunocompetent mouse cancer models will help define the mechanisms underlying immunotherapy resistance. Here, we present a protocol for preparing mouse T cells and generating CAR T cells. We then detail procedures for testing their therapeutic efficacy and tracking them in a syngeneic mouse glioma model. For complete details on the use and execution of this protocol, please refer to Zhang et al.1.

Bioinformatics identification of potential biomarkers and therapeutic targets for ischemic stroke and vascular dementia

Ischemic stroke and vascular dementia, as common cerebrovascular diseases, with the former causing irreversible neurological damage and the latter causing cognitive and memory impairment, are closely related and have long received widespread attention. Currently, the potential causative genes of these two diseases have yet to be investigated, and effective early diagnostic tools for the diseases have not yet emerged. In this study, we screened new potential biomarkers and analyzed new therapeutic targets for both diseases from the perspective of immune infiltration. Two gene expression profiles on ischemic stroke and vascular dementia were obtained from the NCBI GEO database, and key genes were identified by LASSO regression and SVM-RFE algorithms, and key genes were analyzed by GO and KEGG enrichment. The CIBERSORT algorithm was applied to the gene expression profile species of the two diseases to quantify the 24 subpopulations of immune cells. Moreover, logistic regression modeling analysis was applied to illustrate the stability of the key genes in the diagnosis. Finally, the key genes were validated using RT-PCR assay. A total of 105 intersecting DEGs genes were obtained in the 2 sets of GEO datasets, and bioinformatics functional analysis of the intersecting DEGs genes showed that GO was mainly involved in the purine ribonucleoside triphosphate metabolic process，respiratory chain complex，DNA-binding transcription factor binding and active transmembrane transporter activity. KEGG is mainly involved in the Oxidative phosphorylation, cAMP signaling pathway. The LASSO regression algorithm and SVM-RFE algorithm finally obtained three genes, GAS2L1, ARHGEF40 and PFKFB3, and the logistic regression prediction model determined that the three genes, GAS2L1 (AUC: 0.882), ARHGEF40 (AUC: 0.867) and PFKFB3 (AUC: 0.869), had good diagnostic performance. Meanwhile, the two disease core genes and immune infiltration were closely related, GAS2L1 and PFKFB3 had the highest positive correlation with macrophage M1 (p < 0.001) and the highest negative correlation with mast cell activation (p = 0.0017); ARHGEF40 had the highest positive correlation with macrophage M1 and B cells naive (p < 0.001), the highest negative correlation with B cell memory highest correlation (p = 0.0047). RT-PCR results showed that the relative mRNA expression levels of GAS2L1, ARHGEF40, and PFKFB3 were significantly elevated in the populations of both disease groups (p < 0.05). Immune infiltration-based models can be used to predict the diagnosis of patients with ischemic stroke and vascular dementia and provide a new perspective on the early diagnosis and treatment of both diseases.

Immunogenic Extracellular Vesicles Derived from Endoplasmic Reticulum-Stressed Tumor Cells: Implications as the Therapeutic Cancer Vaccine

Tumor-derived extracellular vesicles (TDEs) have potential for therapeutic cancer vaccine applications since they innately possess tumor-associated antigens, mediate antigen presentation, and can incorporate immune adjuvants for enhanced vaccine efficacy. However, the original TDEs also contain immune-suppressive proteins. To address this, we proposed a simple yet powerful preconditioning method to improve the overall immunogenicity of the TDEs. This approach involved inducing endoplasmic reticulum (ER) stress on parental tumor cells via N-glycosylation inhibition with tunicamycin. The generated immunogenic TDEs (iTDEs) contained down-regulated immunosuppressive proteins and up-regulated immune adjuvants, effectively activating dendritic cells (DCs) in vitro. Furthermore, in vivo evidence from a tumor-bearing mouse model showed that iTDEs activated DCs, enabling cytotoxic T lymphocytes (CTLs) to target tumors, and eventually established a systemic antitumor immune response. Additionally, iTDEs significantly delayed tumor recurrence in a postsurgery model compared with control groups. These findings highlight the immense potential of our strategy for utilizing TDEs to develop effective cancer vaccines.

Potential roles for efferocytosis in glioblastoma immune evasion

Glioblastoma is an aggressive and incurable brain cancer. This cancer establishes both local and systemic immunosuppression that creates a major obstacle to effective immunotherapies. Many studies point to tumor-resident myeloid cells (primarily microglia and macrophages) as key mediators of this immunosuppression. Myeloid cells exhibit a high level of plasticity with respect to their phenotype and are capable of both stimulating and repressing immune responses. How glioblastomas recruit myeloid cells and exploit them to avoid the immune system is an active area of research. Macrophages can acquire an immunosuppressive phenotype as a consequence of exposure to cytokines such as TGFB1 or IL4; in addition, macrophages can acquire an immunosuppressive phenotype as a consequence of the engulfment of apoptotic cells, a process referred to as efferocytosis. There is substantial evidence that glioblastoma cells are able to secrete cytokines and other factors that induce an immunosuppressive phenotype in macrophages and microglia. However, less is known about the contribution of efferocytosis to immunosuppression in glioblastoma. Here I review the literature in this area and discuss the potential of efferocytosis inhibition to improve glioblastoma response to immunotherapy.

Immune Escape in Glioblastoma: Mechanisms of Action and Implications for Immune Checkpoint Inhibitors and CAR T-Cell Therapy

Glioblastoma, the most common primary brain cancer in adults, is characterized by a poor prognosis and resistance to standard treatments. The advent of immunotherapy has revolutionized the treatment of several cancers in recent years but has failed to demonstrate benefit in patients with glioblastoma. Understanding the mechanisms by which glioblastoma exerts tumor-mediated immune suppression in both the tumor microenvironment and the systemic immune landscape is a critical step towards developing effective immunotherapeutic strategies. In this review, we discuss the current understanding of immune escape mechanisms in glioblastoma that compromise the efficacy of immunotherapies, with an emphasis on immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy. In parallel, we review data from preclinical studies that have identified additional therapeutic targets that may enhance overall treatment efficacy in glioblastoma when administered alongside existing immunotherapies.

Therapeutic potential of toosendanin: Novel applications of an old ascaris repellent as a drug candidate

Toosendanin (TSN), extracted from Melia. toosendan Sieb.et Zucc. and Melia. azedarach L., has been developed into an ascaris repellent in China. However, with the improvement of public health protection, the incidence of ascariasis has been reduced considerably, resulting in limited medical application of TSN. Therefore, it is questionable whether this old ascaris repellent can develop into a drug candidate. Modern studies have shown that TSN has strong pharmacological activities, including anti-tumor, anti-botulinum, anti-viral and anti-parasitic potentials. It also can regulate fat formation and improve inflammation. These researches indicate that TSN has great potential to be developed into a corresponding medical product. In order to better development and application of TSN, the availability, pharmacodynamics, pharmacokinetics and toxicology of TSN are summarized systematically. In addition, this review discusses shortcomings in the current researches and provides useful suggestions about how TSN developed into a drug candidate. Therefore, this paper illustrates the possibility of developing TSN as a medical product, aimed to provide directions for the clinical application and further research of TSN.

Optimizing CAR-T Therapy for Glioblastoma

Chimeric antigen receptor T-cell therapies have transformed the management of hematologic malignancies but have not yet demonstrated consistent efficacy in solid tumors. Glioblastoma is the most common primary malignant brain tumor in adults and remains a major unmet medical need. Attempts at harnessing the potential of chimeric antigen receptor T-cell therapy for glioblastoma have resulted in glimpses of promise but have been met with substantial challenges. In this focused review, we discuss current and future strategies being developed to optimize chimeric antigen receptor T cells for efficacy in patients with glioblastoma, including the identification and characterization of new target antigens, reversal of T-cell dysfunction with novel chimeric antigen receptor constructs, regulatable platforms, and gene knockout strategies, and the use of combination therapies to overcome the immune-hostile microenvironment.

Bispecific T-Cell Engagers and Chimeric Antigen Receptor T-Cell Therapies in Glioblastoma: An Update

Glioblastoma is the most common malignant primary brain tumor in adults. The prognosis is extremely poor even with standard treatment of maximal safe resection, radiotherapy, and chemotherapy. Recurrence is inevitable within months, and treatment options are very limited. Chimeric antigen receptor T-cell therapy (CART) and bispecific T-cell engagers (TCEs) are two emerging immunotherapies that can redirect T-cells for tumor-specific killing and have shown remarkable success in hematological malignancies and been under extensive study for application in glioblastoma. While there have been multiple clinical trials showing preliminary evidence of safety and efficacy for CART, bispecific TCEs are still in the early stages of clinical testing, with preclinical studies showing very promising results. However, there are multiple shared challenges that need to be addressed in the future, including the route of delivery, antigen escape, the immunosuppressive tumor microenvironment, and toxicity resulting from the limited choice of tumor-specific antigens. Efforts are underway to optimize the design of both these treatments and find the ideal combination therapy to overcome these challenges. In this review, we describe the work that has been performed as well as novel approaches in glioblastoma and in other solid tumors that may be applicable in the future.