Neuroinflammation and immunoregulation in glioblastoma and brain metastases: Recent developments in imaging approaches

Ferroptosis in glioma therapy: advancements in sensitizing strategies and the complex tumor-promoting roles

Ferroptosis, an iron-dependent form of non-apoptotic regulated cell death, is induced by the accumulation of lipid peroxides on cellular membranes. Over the past decade, ferroptosis has emerged as a crucial process implicated in various physiological and pathological systems. Positioned as an alternative modality of cell death, ferroptosis holds promise for eliminating cancer cells that have developed resistance to apoptosis induced by conventional therapeutics. This has led to a growing interest in leveraging ferroptosis for cancer therapy across diverse malignancies. Gliomas are tumors arising from glial or precursor cells, with glioblastoma (GBM) being the most common malignant primary brain tumor that is associated with a dismal prognosis. This review provides a summary of recent advancements in the exploration of ferroptosis-sensitizing methods, with a specific focus on their potential application in enhancing the treatment of gliomas. In addition to summarizing the therapeutic potential, this review also discusses the intricate interplay of ferroptosis and its potential tumor-promoting roles within gliomas. Recognizing these dual roles is essential, as they could potentially complicate the therapeutic benefits of ferroptosis. Exploring strategies aimed at circumventing these tumor-promoting roles could enhance the overall therapeutic efficacy of ferroptosis in the context of glioma treatment.

EDA2R reflects the acute brain response to cranial irradiation in liquid biopsies

BACKGROUND

Cranial radiotherapy is standard of care for high-grade brain tumors and metastases; however, it induces debilitating neurocognitive impairments in cancer survivors, especially children. As the numbers of pediatric brain cancer survivors continue improving, the numbers of individuals developing life-long neurocognitive sequalae are consequently expected to rise. Yet, there are no established biomarkers estimating the degree of the irradiation-induced brain injury at completion of radiotherapy to predict the severity of the expected neurocognitive complications. We aimed to identify sensitive biomarkers associated with brain response to irradiation that can be measured in easily accessible clinical materials, such as liquid biopsies.

METHODS

Juvenile mice were subjected to cranial irradiation with 0.5, 1, 2, 4, and 8 Gy. Cerebrospinal fluid (CSF), plasma, and brains were collected at acute, subacute, and subchronic phases after irradiation, and processed for proteomic screens, and molecular and histological analyses.

RESULTS

We found that the levels of ectodysplasin A2 receptor (EDA2R), member of tumor necrosis factor receptor superfamily, increased significantly in the CSF after cranial irradiation, even at lower irradiation doses. The levels of EDA2R were increased globally in the brain acutely after irradiation and decreased over time. EDA2R was predominantly expressed by neurons, and the temporal dynamics of EDA2R in the brain was reflected in the plasma samples.

CONCLUSIONS

We propose EDA2R as a promising potential biomarker reflecting irradiation-induced brain injury in liquid biopsies. The levels of EDA2R upon completion of radiotherapy may aid in predicting the severity of IR-induced neurocognitive sequalae at a very early stage after treatment.

Evaluation of Blood C Reactive Protein (CRP) and Neutrophil-to-Lymphocyte Ratio (NLR) Utility in Canine Epilepsy

BACKGROUND

The role of neuroinflammation in epileptogenesis has been previously explored, and several biomarkers have been identified as being relevant in assessing the intensity of the inflammatory process. In human medicine, an increased C reactive protein (CRP) blood concentration and/or neutrophil-to-lymphocyte ratio (NLR) is considered a constant finding of epileptic activity. In veterinary medicine, only a few studies have been published regarding both of these topics.

HYPOTHESIS/OBJECTIVES

Our aim was to assess the C reactive protein blood concentration and the neutrophil-to-lymphocyte ratio in epileptic dogs, regardless of etiology.

METHOD

This retrospective study was based on changes in routine blood parameters in 59 dogs with epileptic activity.

RESULTS

An increased C reactive protein concentration was observed mostly in the dogs affected by structural epilepsy, and all epileptic dogs displayed abnormal neutrophil-to-lymphocyte values.

CONCLUSIONS

Based on the authors' knowledge, this is the first report regarding the NLR in epileptic dogs. Both the CRP concentration and the NLR might be considered feasible non-specific markers of the neuroinflamation involved in epileptogenesis and might be used in the diagnosis of and therapeutic approach to cluster seizures in dogs with idiopathic epilepsy and in patients with structural epilepsy. Dogs diagnosed with IEis and high CRP concentrations and NLRs may be subject to non-documented cluster seizures. Both CRP and the NLR have limited diagnostic value in dogs with reactive seizures.

Noninvasive therapy of brain cancer using a unique systemic delivery methodology with a cancer terminator virus

Primary, glioblastoma, and secondary brain tumors, from metastases outside the brain, are among the most aggressive and therapeutically resistant cancers. A physiological barrier protecting the brain, the blood-brain barrier (BBB), functions as a deterrent to effective therapies. To enhance cancer therapy, we developed a cancer terminator virus (CTV), a unique tropism-modified adenovirus consisting of serotype 3 fiber knob on an otherwise Ad5 capsid that replicates in a cancer-selective manner and simultaneously produces a potent therapeutic cytokine, melanoma differentiation-associated gene-7/interleukin-24 (MDA-7/IL-24). A limitation of the CTV and most other viruses, including adenoviruses, is an inability to deliver systemically to treat brain tumors because of the BBB, nonspecific virus trapping, and immune clearance. These obstacles to effective viral therapy of brain cancer have now been overcome using focused ultrasound with a dual microbubble treatment, the focused ultrasound-double microbubble (FUS-DMB) approach. Proof-of-principle is now provided indicating that the BBB can be safely and transiently opened, and the CTV can then be administered in a second set of complement-treated microbubbles and released in the brain using focused ultrasound. Moreover, the FUS-DMB can be used to deliver the CTV multiple times in animals with glioblastoma  growing in their brain thereby resulting in a further enhancement in survival. This strategy permits efficient therapy of primary and secondary brain tumors enhancing animal survival without promoting harmful toxic or behavioral side effects. Additionally, when combined with a standard of care therapy, Temozolomide, a further increase in survival is achieved. The FUS-DMB approach with the CTV highlights a noninvasive strategy to treat brain cancers without surgery. This innovative delivery scheme combined with the therapeutic efficacy of the CTV provides a novel potential translational therapeutic approach for brain cancers.

Targeting inflammation in glioblastoma: An updated review from pathophysiology to novel therapeutic approaches

Glioblastoma (GBM) is a highly aggressive primary malignant brain tumor with a dismal prognosis despite current treatment strategies. Inflammation plays an essential role in GBM pathophysiology, contributing to tumor growth, invasion, immunosuppression, and angiogenesis. As a result, pharmacological intervention with anti-inflammatory drugs has been used as a potential approach for the management of GBM. To provide an overview of the current understanding of GBM pathophysiology, potential therapeutic applications of anti-inflammatory drugs in GBM, conventional treatments of glioblastoma and emerging therapeutic approaches currently under investigation. A narrative review was carried out, scanning publications from 2000 to 2023 on PubMed and Google Scholar. The search was not guided by a set research question or a specific search method but rather focused on the area of interest. Conventional treatments such as surgery, radiotherapy, and chemotherapy have shown some benefits, but their effectiveness is limited by various factors such as tumor heterogeneity and resistance.

A longer time to relapse is associated with a larger increase in differences between paired primary and recurrent IDH wild-type glioblastomas at both the transcriptomic and genomic levels

Glioblastoma (GBM) is the most common malignant brain tumor in adults, which remains incurable and often recurs rapidly after initial therapy. While large efforts have been dedicated to uncover genomic/transcriptomic alternations associated with the recurrence of GBMs, the evolutionary trajectories of matched pairs of primary and recurrent (P-R) GBMs remain largely elusive. It remains challenging to identify genes associated with time to relapse (TTR) and construct a stable and effective prognostic model for predicting TTR of primary GBM patients. By integrating RNA-sequencing and genomic data from multiple datasets of patient-matched longitudinal GBMs of isocitrate dehydrogenase wild-type (IDH-wt), here we examined the associations of TTR with heterogeneities between paired P-R GBMs in gene expression profiles, tumor mutation burden (TMB), and microenvironment. Our results revealed a positive correlation between TTR and transcriptomic/genomic differences between paired P-R GBMs, higher percentages of non-mesenchymal-to-mesenchymal transition and mesenchymal subtype for patients with a short TTR than for those with a long TTR, a high correlation between paired P-R GBMs in gene expression profiles and TMB, and a negative correlation between the fitting level of such a paired P-R GBM correlation and TTR. According to these observations, we identified 55 TTR-associated genes and thereby constructed a seven-gene (ZSCAN10, SIGLEC14, GHRHR, TBX15, TAS2R1, CDKL1, and CD101) prognostic model for predicting TTR of primary IDH-wt GBM patients using univariate/multivariate Cox regression analyses. The risk scores estimated by the model were significantly negatively correlated with TTR in the training set and two independent testing sets. The model also segregated IDH-wt GBM patients into two groups with significantly divergent progression-free survival outcomes and showed promising performance for predicting 1-, 2-, and 3-year progression-free survival rates in all training and testing sets. Our findings provide new insights into the molecular understanding of GBM progression at recurrence and potential targets for therapeutic treatments.

MET receptor serves as a promising target in melanoma brain metastases

The development of brain metastases hallmarks disease progression in 20-40% of melanoma patients and is a serious obstacle to therapy. Understanding the processes involved in the development and maintenance of melanoma brain metastases (MBM) is critical for the discovery of novel therapeutic strategies. Here, we generated transcriptome and methylome profiles of MBM showing high or low abundance of infiltrated Iba1high tumor-associated microglia and macrophages (TAMs). Our survey identified potential prognostic markers of favorable disease course and response to immune checkpoint inhibitor (ICi) therapy, among them APBB1IP and the interferon-responsive gene ITGB7. In MBM with high ITGB7/APBB1IP levels, the accumulation of TAMs correlated significantly with the immune score. Signature-based deconvolution of MBM via single sample GSEA revealed enrichment of interferon-response and immune signatures and revealed inflammation, stress and MET receptor signaling. MET receptor phosphorylation/activation maybe elicited by inflammatory processes in brain metastatic melanoma cells via stroma cell-released HGF. We found phospho-METY1234/1235 in a subset of MBM and observed a marked response of brain metastasis-derived cell lines (BMCs) that lacked druggable BRAF mutations or developed resistance to BRAF inhibitors (BRAFi) in vivo to MET inhibitors PHA-665752 and ARQ197 (tivantinib). In summary, the activation of MET receptor in brain colonizing melanoma cells by stromal cell-released HGF may promote tumor self-maintenance and expansion and might counteract ICi therapy. Therefore, therapeutic targeting of MET possibly serves as a promising strategy to control intracranial progressive disease and improve patient survival.

The Role of Progranulin (PGRN) in the Pathogenesis of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) represents the most common and aggressive malignant form of brain tumour in adults and is characterized by an extremely poor prognosis with dismal survival rates. Currently, expanding concepts concerning the pathophysiology of GBM are inextricably linked with neuroinflammatory phenomena. On account of this fact, the identification of novel pathomechanisms targeting neuroinflammation seems to be crucial in terms of yielding successful individual therapeutic strategies. In recent years, the pleiotropic growth factor progranulin (PGRN) has attracted significant attention in the neuroscience and oncological community regarding its neuroimmunomodulatory and oncogenic functions. This review of the literature summarizes and updates contemporary knowledge about PGRN, its associated receptors and signalling pathway involvement in GBM pathogenesis, indicating possible cellular and molecular mechanisms with potential diagnostic, prognostic and therapeutic targets in order to yield successful individual therapeutic strategies. After a review of the literature, we found that there are possible PGRN-targeted therapeutic approaches for implementation in GBM treatment algorithms both in preclinical and future clinical studies. Furthermore, PGRN-targeted therapies exerted their highest efficacy in combination with other established chemotherapeutic agents, such as temozolomide. The results of the analysis suggested that the possible implementation of routine determinations of PGRN and its associated receptors in tumour tissue and biofluids could serve as a diagnostic and prognostic biomarker of GBM. Furthermore, promising preclinical applications of PGRN-related findings should be investigated in clinical studies in order to create new diagnostic and therapeutic algorithms for GBM treatment.

Harnessing immunotherapy for brain metastases: insights into tumor-brain microenvironment interactions and emerging treatment modalities

Brain metastases signify a deleterious milestone in the progression of several advanced cancers, predominantly originating from lung, breast and melanoma malignancies, with a median survival timeframe nearing six months. Existing therapeutic regimens yield suboptimal outcomes; however, burgeoning insights into the tumor microenvironment, particularly the immunosuppressive milieu engendered by tumor-brain interplay, posit immunotherapy as a promising avenue for ameliorating brain metastases. In this review, we meticulously delineate the research advancements concerning the microenvironment of brain metastases, striving to elucidate the panorama of their onset and evolution. We encapsulate three emergent immunotherapeutic strategies, namely immune checkpoint inhibition, chimeric antigen receptor (CAR) T cell transplantation and glial cell-targeted immunoenhancement. We underscore the imperative of aligning immunotherapy development with in-depth understanding of the tumor microenvironment and engendering innovative delivery platforms. Moreover, the integration with established or avant-garde physical methodologies and localized applications warrants consideration in the prevailing therapeutic schema.

Cytokine Profile in Development of Glioblastoma in Relation to Healthy Individuals

Cytokines play an essential role in the control of tumor cell development and multiplication. However, the available literature provides ambiguous data on the involvement of these proteins in the formation and progression of glioblastoma (GBM). This study was designed to evaluate the inflammatory profile and to investigate its potential for the identification of molecular signatures specific to GBM. Fifty patients aged 66.0 ± 10.56 years with newly diagnosed high-grade gliomas and 40 healthy individuals aged 71.7 ± 4.9 years were included in the study. White blood cells were found to fall within the referential ranges and were significantly higher in GBM than in healthy controls. Among immune cells, neutrophils showed the greatest changes, resulting in elevated neutrophil-to-lymphocyte ratio (NLR). The neutrophil count inversely correlated with survival time expressed by Spearman's coefficient rs = -0.359 (p = 0.010). The optimal threshold values corresponded to 2.630 × 103/µL for NLR (the area under the ROC curve AUC = 0.831, specificity 90%, sensitivity 76%, the relative risk RR = 7.875, the confidence intervals 95%CI 3.333-20.148). The most considerable changes were recorded in pro-inflammatory cytokines interleukin IL-1β, IL-6, and IL-8, which were approx. 1.5-2-fold higher, whereas tumor necrosis factor α (TNFα) and high mobility group B1 (HMGB1) were lower in GBM than healthy control (p < 0.001). The results of the ROC, AUC, and RR analysis of IL-1β, IL-6, IL-8, and IL-10 indicate their high diagnostics potential for clinical prognosis. The highest average RR was observed for IL-6 (RR = 2.923) and IL-8 (RR = 3.151), which means there is an approx. three-fold higher probability of GBM development after exceeding the cut-off values of 19.83 pg/mL for IL-6 and 10.86 pg/mL for IL-8. The high values of AUC obtained for the models NLR + IL-1β (AUC = 0.907), NLR + IL-6 (AUC = 0.908), NLR + IL-8 (AUC = 0.896), and NLR + IL-10 (AUC = 0.887) prove excellent discrimination of GBM patients from healthy individuals and may represent GBM-specific molecular signatures.

In Situ Detection of Neuroinflammation using Multi-cellular 3D Neurovascular Unit-on-a-Chip

The human neurovascular system is a complex network of blood vessels and brain cells that is essential to the proper functioning of the brain. In recent years, researchers have become increasingly interested in the role of this system in developing drugs to treat neuroinflammation. This process is believed to contribute to the development of several neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. While much remains to be learned about the precise mechanisms by which the neurovascular system interacts with the brain and how it can be targeted for therapeutic purposes, this area of research holds great promise for the future of neurology and medicine. Currently, creating neurovascular models begins with animal models, followed by testing on humans in clinical trials. However, the high number of medication failures that pass through animal testing indicates that animal models do not always reflect the outcome of human clinical trials. To overcome the challenges of neurovascular systems and the issues with animal models, we have developed a one-of-a-kind in vitro neurovascular unit-on-a-chip to accurately replicate the in vivo human neurovascular microenvironment. This neuroinflammation-on-a-chip platform has the potential to enhance the current methods of drug development and testing to treat neurodegenerative diseases. By replicating the human neurovascular unit in vitro, a more accurate representation of human physiology can be achieved compared to animal models. The ability to detect pro-inflammatory cytokines in situ and monitor physiological changes, such as barrier function, in real-time can provide an invaluable tool for evaluating the efficacy and safety of drugs. Moreover, using nano-sized graphene oxide for in situ detection of inflammatory responses is an innovative approach that can advance the field of neuroinflammation research. Overall, our developed neuroinflammation-on-a-chip system has the potential to provide a more efficient and effective method for developing drugs for treating neurodegenerative diseases and other central nervous system (CNS) diseases.

Amyloids and brain cancer: molecular linkages and crossovers

Amyloids are high-order proteinaceous formations deposited in both intra- and extracellular spaces. These aggregates have tendencies to deregulate cellular physiology in multiple ways; for example, altered metabolism, mitochondrial dysfunctions, immune modulation, etc. When amyloids are formed in brain tissues, the endpoint often is death of neurons. However, interesting but least understood is a close connection of amyloids with another set of conditions in which brain cells proliferate at an extraordinary rate and form tumor inside brain. Glioblastoma is one such condition. Increasing number of evidence indicate a possible link between amyloid formation and depositions in brain tumors. Several proteins associated with cell cycle regulation and apoptotic pathways themselves have shown to possess high tendencies to form amyloids. Tumor suppressor protein p53 is one prominent example that mutate, oligomerize and form amyloids leading to loss- or gain-of-functions and cause increased cell proliferation and malignancies. In this review article, we present available examples, genetic links and common pathways that indicate that possibly the two distantly placed pathways: amyloid formation and developing cancers in the brain have similarities and are mechanistically intertwined together.

Dysregulation of inflammasome activation in glioma

Gliomas are the most common brain tumors characterized by complicated heterogeneity. The genetic, molecular, and histological pathology of gliomas is characterized by high neuro-inflammation. The inflammatory microenvironment in the central nervous system (CNS) has been closely linked with inflammasomes that control the inflammatory response and coordinate innate host defenses. Dysregulation of the inflammasome causes an abnormal inflammatory response, leading to carcinogenesis in glioma. Because of the clinical importance of the various physiological properties of the inflammasome in glioma, the inflammasome has been suggested as a promising treatment target for glioma management. Here, we summarize the current knowledge on the contribution of the inflammasomes in glioma and therapeutic insights. Video Abstract.

Advances in the application of neuroinflammatory molecular imaging in brain malignancies

The prevalence of brain cancer has been increasing in recent decades, posing significant healthcare challenges. The introduction of immunotherapies has brought forth notable diagnostic imaging challenges for brain tumors. The tumor microenvironment undergoes substantial changes in induced immunosuppression and immune responses following the development of primary brain tumor and brain metastasis, affecting the progression and metastasis of brain tumors. Consequently, effective and accurate neuroimaging techniques are necessary for clinical practice and monitoring. However, patients with brain tumors might experience radiation-induced necrosis or other neuroinflammation. Currently, positron emission tomography and various magnetic resonance imaging techniques play a crucial role in diagnosing and evaluating brain tumors. Nevertheless, differentiating between brain tumors and necrotic lesions or inflamed tissues remains a significant challenge in the clinical diagnosis of the advancements in immunotherapeutics and precision oncology have underscored the importance of clinically applicable imaging measures for diagnosing and monitoring neuroinflammation. This review summarizes recent advances in neuroimaging methods aimed at enhancing the specificity of brain tumor diagnosis and evaluating inflamed lesions.

Glucose Infusion Induced Change in Intracellular pH and Its Relationship with Tumor Glycolysis in a C6 Rat Model of Glioblastoma

INTRODUCTION

The reliance on glycolytic metabolism is a hallmark of tumor metabolism. Excess acid and protons are produced, leading to an acidic tumor environment. Therefore, we explored the relationship between the tumor glycolytic metabolism and tissue pH by comparing ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) and hyperpolarized [1-¹³C]pyruvate MR spectroscopy imaging (MRSI) to chemical exchange saturation transfer (CEST) MRI measurements of tumor pH.

METHODS

10⁶ C6 glioma cells were implanted in the brains of male Wistar rats (N = 11) using stereotactic surgery. A 60-min PET acquisition after a bolus of FDG was performed at 11-13 days post implantation, and standardized uptake value (SUV) was calculated. CEST measurements were acquired the following day before and during constant infusion of glucose solution. Tumor intracellular pH (pHi) was evaluated using amine and amide concentration-independent detection (AACID) CEST MRI. The change of pH_i (∆pH_i) was calculated as the difference between pH_i pre- and during glucose infusion. Rats were imaged immediately with hyperpolarized [1-¹³C]pyruvate MRSI. Regional maps of the ratio of Lac:Pyr were acquired. The correlations between SUV, Lac:Pyr ratio, and ∆pH_i were evaluated using Pearson's correlation.

RESULTS

A decrease of 0.14 in pH_i was found after glucose infusion in tumor region. Significant correlations between tumor glycolysis measurements of Lac:Pyr and ∆pH_i within the tumor (ρ = 0.83, P = 0.01) and peritumoral region (ρ = 0.76, P = 0.028) were observed. No significant correlations were found between tumor SUV and ∆pH_i within the tumor (ρ =  - 0.45, P = 0.17) and peritumor regions (ρ =  - 0.6, P = 0.051).

CONCLUSION

AACID detected the changes in pH_i induced by glucose infusion. Significant correlations between tumor glycolytic measurement of Lac:Pyr and tumoral and peritumoral pH_i and ∆pH_i suggest the intrinsic relationship between tumor glycolytic metabolism and the tumor pH environment as well as the peritumor pH environment.

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Steroid utility, immunotherapy, and brain tumor management: an update on conflicting therapies

Steroid use is a widely accepted practice for both the treatment and prevention of tumor-induced edema, but there are many unknowns regarding their current clinical utility with modern anti-tumor therapies. This decreases edema and relieves the symptomatic mass effect. There are clearly understood benefits and commonly accepted complications of methylprednisolone (MP) use, but the topic is recently controversial. With immunotherapy advancing, a robust immune response is crucial for full therapeutic efficacy. The immunosuppression of MP may interfere with future and current therapeutics relying on the integrity of the patient’s immune system. This further emphasizes the need for alternative agents to effectively treat tumor-induced cerebral edema. This review highlights the current clinical utility of steroids to treat brain tumor-related edema and the underlying pathophysiology. It also reviews details regarding different steroid formulations and dosing. Research available regarding concurrent steroid use with immunotherapy is detailed next, followed by alternatives to steroids and barriers to their adoption. Finally, this paper discusses pre-clinical findings and emerging treatments aimed to augment or replace steroid use.

Molecular Imaging of Ultrasound-Mediated Blood-Brain Barrier Disruption in a Mouse Orthotopic Glioblastoma Model

Glioblastoma (GBM) is an aggressive and malignant primary brain tumor. The blood-brain barrier (BBB) limits the therapeutic options available to tackle this incurable tumor. Transient disruption of the BBB by focused ultrasound (FUS) is a promising and safe approach to increase the brain and tumor concentration of drugs administered systemically. Non-invasive, sensitive, and reliable imaging approaches are required to better understand the impact of FUS on the BBB and brain microenvironment. In this study, nuclear imaging (SPECT/CT and PET/CT) was used to quantify neuroinflammation 48 h post-FUS and estimate the influence of FUS on BBB opening and tumor growth in vivo. BBB disruptions were performed on healthy and GBM-bearing mice (U-87 MG xenograft orthotopic model). The BBB recovery kinetics were followed and quantified by [99mTc]Tc-DTPA SPECT/CT imaging at 0.5 h, 3 h and 24 h post-FUS. The absence of neuroinflammation was confirmed by [18F]FDG PET/CT imaging 48 h post-FUS. The presence of the tumor and its growth were evaluated by [68Ga]Ga-RGD₂ PET/CT imaging and post-mortem histological analysis, showing that tumor growth was not influenced by FUS. In conclusion, molecular imaging can be used to evaluate the time frame for systemic treatment combined with transient BBB opening and to test its efficacy over time.

Chronic Inflammation Pathway NF-κB Cooperates with Epigenetic Reprogramming to Drive the Malignant Progression of Glioblastoma

Without an effective strategy for targeted therapy, glioblastoma is still incurable with a median survival of only 15 months. Both chronic inflammation and epigenetic reprogramming are hallmarks of cancer. However, the mechanisms and consequences of their cooperation in glioblastoma remain unknown. Here, we discover that chronic inflammation governs H3K27me3 reprogramming in glioblastoma through the canonical NF-κB pathway to target EZH2. Being a crucial mediator of chronic inflammation, the canonical NF-κB signalling specifically directs the expression and redistribution of H3K27me3 but not H3K4me3, H3K9me3 and H3K36me3. Using RNA-seq screening to focus on genes encoding methyltransferases and demethylases of histone, we identify EZH2 as a key methyltransferase to control inflammation-triggered epigenetic reprogramming in gliomagenesis. Mechanistically, NF-κB selectively drives the expression of EZH2 by activating its transcription, consequently resulting in a global change in H3K27me3 expression and distribution. Furthermore, we find that co-activation of NF-κB and EZH2 confers the poorest clinical outcome, and that the risk for glioblastoma can be accurately molecularly stratified by NF-κB and EZH2. It is notable that NF-κB can potentially cooperate with EZH2 in more than one way, and most importantly, we demonstrate a Synergistic effect of cancer cells induced by combinatory inhibition of NF-κB and EZH2, which both are frequently over-activated in glioblastoma. In summary, we uncover a functional cooperation between chronic inflammation and epigenetic reprogramming in glioblastoma, combined targeting of which by inhibitors guaranteed in safety and availability furnishes a potent strategy for effective treatment of this fatal disease.

Prognostic Values of Combined Ratios of White Blood Cells in Glioblastoma: A Retrospective Study

In some malignant tumours, the changes in neutrophil counts in relation to other blood cells are connected with unfavourable prognosis. Nevertheless, the prognostic value of the combinations of the haematological components in glioblastoma (GBM) remains under dispute. The clinical significance of the neutrophil-to-lymphocyte ratio (NLR), systemic immune inflammation index (SII), and systemic inflammation response index (SIRI) was investigated in our study. We retrospectively studied 358 patients (males n = 195; females n = 163) aged 59.9 ± 13.5 yrs with newly diagnosed glioma and admitted to the Neurosurgery Centre. Routine blood tests and clinical characteristics were recorded within the first hour of hospital admission. The inflammatory variables: NLR, SII and SIRI exceeded the reference values and were significantly elevated in Grade 3 and Grade 4 tumour. The Cox model analysis showed that the age ≥ 63 years, NLR ≥ 4.56 × 103/µL, SII ≥ 2003 × 103/µL and SIRI ≥ 3.03 × 103/µL significantly increased the risk of death in Grade 4 tumour patients. In the inflammatory variables, NLR demonstrated the highest impact on the survival time (HR 1.56; 95% CI 1.145-2.127; p = 0.005). In the first Polish study including GBM patients, the age in relation to simple parameters derived from complete blood cell count were found to have prognostic implications in the survival rate.

DTI Abnormalities Related to Glioblastoma: A Prospective Comparative Study with Metastasis and Healthy Subjects

(1) Background: Glioblastoma multiforme (GBM) shows complex mechanisms of spreading of the tumor cells, up to remote areas, and little is still known of these mechanisms, thus we focused on MRI abnormalities observable in the tumor and the brain adjacent to the lesion, up to the contralateral hemisphere, with a special interest on tensor diffusion imaging informing on white matter architecture; (2) Material and Methods: volumes, macroscopic volume (MV), brain-adjacent-tumor (BAT) volume and abnormal color-coded DTI volume (aCCV), and region-of-interest samples (probe volumes, ipsi, and contra lateral to the lesion), with their MRI characteristics, apparent diffusion coefficient (ADC), fractional anisotropy (FA) values, and number of fibers (DTI fiber tracking) were analyzed in patients suffering GBM (n = 15) and metastasis (n = 9), and healthy subjects (n = 15), using ad hoc statistical methods (type I error = 5%) (3) Results: GBM volumes were larger than metastasis volumes, aCCV being larger in GBM and BAT ADC was higher in metastasis, ADC decreased centripetally in metastasis, FA increased centripetally either in GBM or metastasis, MV and BAT FA values were higher in GBM, ipsi FA values of GBM ROIs were higher than those of metastasis, and the GBM ipsi number of fibers was higher than the GBM contra number of fibers; (4) Conclusions: The MV, BAT and especially the aCCV, as well as their related water diffusion characteristics, could be useful biomarkers in oncology and functional oncology.

Progress and Viewpoints of Multifunctional Composite Nanomaterials for Glioblastoma Theranostics

The most common malignant tumor of the brain is glioblastoma multiforme (GBM) in adults. Many patients die shortly after diagnosis, and only 6% of patients survive more than 5 years. Moreover, the current average survival of malignant brain tumors is only about 15 months, and the recurrence rate within 2 years is almost 100%. Brain diseases are complicated to treat. The reason for this is that drugs are challenging to deliver to the brain because there is a blood–brain barrier (BBB) protection mechanism in the brain, which only allows water, oxygen, and blood sugar to enter the brain through blood vessels. Other chemicals cannot enter the brain due to their large size or are considered harmful substances. As a result, the efficacy of drugs for treating brain diseases is only about 30%, which cannot satisfy treatment expectations. Therefore, researchers have designed many types of nanoparticles and nanocomposites to fight against the most common malignant tumors in the brain, and they have been successful in animal experiments. This review will discuss the application of various nanocomposites in diagnosing and treating GBM. The topics include (1) the efficient and long-term tracking of brain images (magnetic resonance imaging, MRI, and near-infrared light (NIR)); (2) breaking through BBB for drug delivery; and (3) natural and chemical drugs equipped with nanomaterials. These multifunctional nanoparticles can overcome current difficulties and achieve progressive GBM treatment and diagnosis results.

Imaging immune responses in neuroinflammatory diseases

Innate and adaptive immune responses in the central nervous system (CNS) play critical roles in the pathogenesis of neurological diseases. In the first of a two-part special issue, leading researchers discuss how imaging modalities are used to monitor immune responses in several neurodegenerative diseases and glioblastoma and brain metastases. While comparative studies in humans between imaging and pathology are biased towards the end stage of disease, animal models can inform regarding how immune responses change with disease progression and as a result of treatment regimens. Magnetic resonance imaging (MRI) and positron emission tomography (PET) are frequently used to image disease progression, and the articles indicate how one or more of these modalities have been applied to specific neuroimmune diseases. In addition, advanced microscopical imaging using two-dimensional photon microscopy and in vitro live cell imaging have also been applied to animal models. In this special issue (Parts 1 and 2), as well as the imaging modalities mentioned, several articles discuss biomarkers of disease and microscopical studies that have enabled characterization of immune responses. Future developments of imaging modalities should enable tracking of specific subsets of immune cells during disease allowing longitudinal monitoring of immune responses. These new approaches will be critical to more effectively monitor and thus target specific cell subsets for therapeutic interventions which may be applicable to a range of neurological diseases.

Neuroinflammation and immunoregulation in glioblastoma and brain metastases: Recent developments in imaging approaches

Brain tumors and brain metastases induce changes in brain tissue remodeling that lead to immunosuppression and trigger an inflammatory response within the tumor microenvironment. These immune and inflammatory changes can influence invasion and metastasis. Other neuroinflammatory and necrotic lesions may occur in patients with brain cancer or brain metastases as sequelae from treatment with radiotherapy. Glioblastoma (GBM) is the most aggressive primary malignant brain cancer in adults. Imaging methods such as positron emission tomography (PET) and different magnetic resonance imaging (MRI) techniques are highly valuable for the diagnosis and therapeutic evaluation of GBM and other malignant brain tumors. However, differentiating between tumor tissue and inflamed brain tissue with imaging protocols remains a challenge. Here, we review recent advances in imaging methods that have helped to improve the specificity of primary tumor diagnosis versus evaluation of inflamed and necrotic brain lesions. We also comment on advances in differentiating metastasis from neuroinflammation processes. Recent advances include the radiosynthesis of ¹⁸ F-FIMP, an L-type amino acid transporter 1 (LAT1)-specific PET probe that allows clearer differentiation between tumor tissue and inflammation compared to previous probes, and the combination of different advanced imaging protocols with the inclusion of radiomics and machine learning algorithms.