Leukaemia hijacks a neural mechanism to invade the central nervous system

The path to leptomeningeal metastasis

The leptomeninges, the cerebrospinal-fluid-filled tissues surrounding the central nervous system, play host to various pathologies including infection, neuroinflammation and malignancy. Spread of systemic cancer into this space, termed leptomeningeal metastasis, occurs in 5-10% of patients with solid tumours and portends a bleak clinical prognosis. Previous, predominantly descriptive, clinical studies have provided few insights. Recent development of preclinical leptomeningeal metastasis models, alongside genomic, transcriptomic and proteomic sequencing efforts, has provided groundwork for mechanistic understanding and identification of long-needed therapeutic targets. Although previously understood as an anatomically isolated compartment, the leptomeninges are increasingly appreciated as a major conduit of communication between the systemic circulation and the central nervous system. Despite the unique nature of the leptomeningeal microenvironment, the general principles of metastasis hold true: cells metastasizing to the leptomeninges must gain access to the new environment, survive within the space and evade the immune system. The study of leptomeningeal metastasis has the potential to uncover novel site-specific metastatic principles and illuminate the physiology of the leptomeningeal space. In this Review, we provide a biology-focused overview of how metastatic cells reach the leptomeninges, thrive in this nutritionally sparse environment and evade the detection of the omnipresent immune system.

An unexpected corridor to brain metastasis

Breast cancer cells migrate from the bone marrow to the leptomeninges.

Breast cancer exploits neural signaling pathways for bone-to-meninges metastasis

The molecular mechanisms that regulate breast cancer cell (BCC) metastasis and proliferation within the leptomeninges (LM) are poorly understood, which limits the development of effective therapies. In this work, we show that BCCs in mice can invade the LM by abluminal migration along blood vessels that connect vertebral or calvarial bone marrow and meninges, bypassing the blood-brain barrier. This process is dependent on BCC engagement with vascular basement membrane laminin through expression of the neuronal pathfinding molecule integrin α6. Once in the LM, BCCs colocalize with perivascular meningeal macrophages and induce their expression of the prosurvival neurotrophin glial-derived neurotrophic factor (GDNF). Intrathecal GDNF blockade, macrophage-specific GDNF ablation, or deletion of the GDNF receptor neural cell adhesion molecule (NCAM) from BCCs inhibits breast cancer growth within the LM. These data suggest integrin α6 and the GDNF signaling axis as new therapeutic targets against breast cancer LM metastasis.

Brain border-associated macrophages: common denominators in infection, aging, and Alzheimer's disease?

Mammalian brain border-associated macrophages (BAMs) are strategically positioned to support vital properties and processes: for example, the composition of the brain's perivascular extracellular matrix and cerebrospinal fluid flow via the glymphatic pathway. BAMs also effectively restrict the spread of infectious microbes into the brain. However, while fighting infections, BAMs sustain long-term transcriptomic changes and can be replaced by inflammatory monocytes, potentially leading to a gradual loss of their beneficial homeostatic functions. We hypothesize that by expediting the deterioration of BAMs, multiple infection episodes might be associated with accelerated brain aging and the putative development of neurodegenerative diseases. Our viewpoint is supported by recent studies suggesting that rejuvenating aged BAMs, and counterbalancing their detrimental inflammatory signatures during infections, might hold promise in treating aging-related neurological disorders, including Alzheimer's disease (AD).

Vessel co-option: a unique vascular-immune niche in liver cancer

Tumor vasculature is pivotal in regulating tumor perfusion, immune cell infiltration, metastasis, and invasion. The vascular status of the tumor is intricately linked to its immune landscape and response to immunotherapy. Vessel co-option means that tumor tissue adeptly exploits pre-existing blood vessels in the para-carcinoma region to foster its growth rather than inducing angiogenesis. It emerges as a significant mechanism contributing to anti-angiogenic therapy resistance. Different from angiogenic tumors, vessel co-option presents a distinctive vascular-immune niche characterized by varying states and distribution of immune cells, including T-cells, tumor-associated macrophages, neutrophils, and hepatic stellate cells. This unique composition contributes to an immunosuppressive tumor microenvironment that is crucial in modulating the response to cancer immunotherapy. In this review, we systematically reviewed the evidence and molecular mechanisms of vessel co-option in liver cancer, while also exploring its implications for anti-angiogenic drug resistance and the immune microenvironment, to provide new ideas and clues for screening patients with liver cancer who are effective in immunotherapy.

Involvement of BCR::ABL1 in laminin adhesion of Philadelphia chromosome-positive acute lymphoblastic leukemia through upregulation of integrin α6

BACKGROUND

Adhesion of cancer cells to extracellular matrix laminin through the integrin superfamily reportedly induces drug resistance. Heterodimers of integrin α6 (CD49f) with integrin β1 (CD29) or β4 (CD104) are major functional receptors for laminin. Higher CD49f expression is reportedly associated with a poorer response to induction therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Moreover, a xenograft mouse model transplanted with primary BCP-ALL cells revealed that neutralized antibody against CD49f improved survival after chemotherapy.

AIMS

Considering the poor outcomes in Philadelphia chromosome (Ph)-positive ALL treated with conventional chemotherapy without tyrosine kinase inhibitors, we sought to investigate an involvement of the laminin adhesion.

METHODS AND RESULTS

Ph-positive ALL cell lines expressed the highest levels of CD49f among the BCP-ALL cell lines with representative translocations, while CD29 and CD104 were ubiquitously expressed in BCP-ALL cell lines. The association of Ph-positive ALL with high levels of CD49f gene expression was also confirmed in two databases of childhood ALL cohorts. Ph-positive ALL cell lines attached to laminin and their laminin-binding properties were disrupted by blocking antibodies against CD49f and CD29 but not CD104. The cell surface expression of CD49f, but not CD29 and CD104, was downregulated by imatinib treatment in Ph-positive ALL cell lines, but not in their T315I-acquired sublines. Consistently, the laminin-binding properties were disrupted by the imatinib pre-treatment in the Ph-positive ALL cell line, but not in its T315I-acquired subline.

CONCLUSION

BCR::ABL1 plays an essential role in the laminin adhesion of Ph-positive ALL cells through upregulation of CD49f.

The anatomic basis of leptomeningeal metastasis

Leptomeningeal metastasis (LM), or spread of cancer to the cerebrospinal fluid (CSF)-filled space surrounding the central nervous system, is a fatal complication of cancer. Entry into this space poses an anatomical challenge for cancer cells; movement of cells between the blood and CSF is tightly regulated by the blood-CSF barriers. Anatomical understanding of the leptomeninges provides a roadmap of corridors for cancer entry. This Review describes the anatomy of the leptomeninges and routes of cancer spread to the CSF. Granular understanding of LM by route of entry may inform strategies for novel diagnostic and preventive strategies as well as therapies.

Identification of direct connections between the dura and the brain

The arachnoid barrier delineates the border between the central nervous system and dura mater. Although the arachnoid barrier creates a partition, communication between the central nervous system and the dura mater is crucial for waste clearance and immune surveillance1,2. How the arachnoid barrier balances separation and communication is poorly understood. Here, using transcriptomic data, we developed transgenic mice to examine specific anatomical structures that function as routes across the arachnoid barrier. Bridging veins create discontinuities where they cross the arachnoid barrier, forming structures that we termed arachnoid cuff exit (ACE) points. The openings that ACE points create allow the exchange of fluids and molecules between the subarachnoid space and the dura, enabling the drainage of cerebrospinal fluid and limited entry of molecules from the dura to the subarachnoid space. In healthy human volunteers, magnetic resonance imaging tracers transit along bridging veins in a similar manner to access the subarachnoid space. Notably, in neuroinflammatory conditions such as experimental autoimmune encephalomyelitis, ACE points also enable cellular trafficking, representing a route for immune cells to directly enter the subarachnoid space from the dura mater. Collectively, our results indicate that ACE points are a critical part of the anatomy of neuroimmune communication in both mice and humans that link the central nervous system with the dura and its immunological diversity and waste clearance systems.

Skull and vertebral bone marrow in central nervous system inflammation

Emerging evidence has highlighted the capacity of hematogenous cells in skull and vertebral bone marrow to enter the meningeal borders via ossified vascular channels and maintain immune homeostasis in the central nervous system (CNS). CNS-adjacent skull and vertebral bone marrow comprises hematopoietic niches that can sense CNS injury and supply specialized immune cells to fine-tune inflammatory responses. Here, we review recent advances in our understanding of skull and vertebral bone marrow-derived immune cells in homeostasis and inflammatory CNS diseases. Further, we discuss the implications for future development of therapies to mitigate CNS inflammation and its detrimental sequelae in neurological disorders.

Role of meningeal immunity in brain function and protection against pathogens

The brain and spinal cord collectively referred to as the Central Nervous System (CNS) are protected by the blood-brain barrier that limits molecular, microbial and immunological trafficking. However, in the last decade, many studies have emphasized the protective role of 'border regions' at the surface of the CNS which are highly immunologically active, in contrast with the CNS parenchyma. In the steady-state, lymphoid and myeloid cells residing in the cranial meninges can affect brain function and behavior. Upon infection, they provide a first layer of protection against microbial neuroinvasion. The maturation of border sites over time enables more effective brain protection in adults as compared to neonates. Here, we provide a comprehensive update on the meningeal immune system and its role in physiological brain function and protection against infectious agents.

Decoding leukemia at the single-cell level: clonal architecture, classification, microenvironment, and drug resistance

Leukemias are refractory hematological malignancies, characterized by marked intrinsic heterogeneity which poses significant obstacles to effective treatment. However, traditional bulk sequencing techniques have not been able to effectively unravel the heterogeneity among individual tumor cells. With the emergence of single-cell sequencing technology, it has bestowed upon us an unprecedented resolution to comprehend the mechanisms underlying leukemogenesis and drug resistance across various levels, including the genome, epigenome, transcriptome and proteome. Here, we provide an overview of the currently prevalent single-cell sequencing technologies and a detailed summary of single-cell studies conducted on leukemia, with a specific focus on four key aspects: (1) leukemia's clonal architecture, (2) frameworks to determine leukemia subtypes, (3) tumor microenvironment (TME) and (4) the drug-resistant mechanisms of leukemia. This review provides a comprehensive summary of current single-cell studies on leukemia and highlights the markers and mechanisms that show promising clinical implications for the diagnosis and treatment of leukemia.

Imaging of brain barrier inflammation and brain fluid drainage in human neurological diseases

The intricate relationship between the central nervous system (CNS) and the immune system plays a crucial role in the pathogenesis of various neurological diseases. Understanding the interactions among the immunopathological processes at the brain borders is essential for advancing our knowledge of disease mechanisms and developing novel diagnostic and therapeutic approaches. In this review, we explore the emerging role of neuroimaging in providing valuable insights into brain barrier inflammation and brain fluid drainage in human neurological diseases. Neuroimaging techniques have enabled us not only to visualize and assess brain structures, but also to study the dynamics of the CNS in health and disease in vivo. By analyzing imaging findings, we can gain a deeper understanding of the immunopathology observed at the brain-immune interface barriers, which serve as critical gatekeepers that regulate immune cell trafficking, cytokine release, and clearance of waste products from the brain. This review explores the integration of neuroimaging data with immunopathological findings, providing valuable insights into brain barrier integrity and immune responses in neurological diseases. Such integration may lead to the development of novel diagnostic markers and targeted therapeutic approaches that can benefit patients with neurological disorders.

The Inhibition of Vessel Co-Option as an Emerging Strategy for Cancer Therapy

Vessel co-option (VCO) is a non-angiogenic mechanism of vascularization that has been associated to anti-angiogenic therapy. In VCO, cancer cells hijack the pre-existing blood vessels and use them to obtain oxygen and nutrients and invade adjacent tissue. Multiple primary tumors and metastases undergo VCO in highly vascularized tissues such as the lungs, liver or brain. VCO has been associated with a worse prognosis. The cellular and molecular mechanisms that undergo VCO are poorly understood. Recent studies have demonstrated that co-opted vessels show a quiescent phenotype in contrast to angiogenic tumor blood vessels. On the other hand, it is believed that during VCO, cancer cells are adhered to basement membrane from pre-existing blood vessels by using integrins, show enhanced motility and a mesenchymal phenotype. Other components of the tumor microenvironment (TME) such as extracellular matrix, immune cells or extracellular vesicles play important roles in vessel co-option maintenance. There are no strategies to inhibit VCO, and thus, to eliminate resistance to anti-angiogenic therapy. This review summarizes all the molecular mechanisms involved in vessel co-option analyzing the possible therapeutic strategies to inhibit this process.

Simulating neuronal development: exploring potential mechanisms for central nervous system metastasis in acute lymphoblastic leukemia

Background

Acute lymphoblastic leukemia (ALL) is prone to metastasize to the central nervous system (CNS), which is an important cause of poor treatment outcomes and unfavorable prognosis. However, the pathogenesis of CNS metastasis of ALL cells has not been fully illuminated. Recent reports have shed some light on the correlation between neural mechanisms and ALL CNS metastasis. These progressions prompt us to study the relationship between ALL central nervous system metastasis and neuronal development, exploring potential biomarkers and therapeutic targets of CNS metastasis.

Materials and methods

ALL central nervous system metastasis- and neuronal development-related differentially expressed genes (DEGs) were identified by analyzing gene expression datasets GSE60926 and GSE13715. Target prediction and network analysis methods were applied to assess protein-protein interaction networks. Gene Ontology (GO) terms and pathway enrichment for DEGs were assessed. Co-expressed differentially expressed genes (co-DEGs) coupled with corresponding predicted microRNAs (miRNAs) were studied as well. Reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry were employed for the validation of key co-DEGs in primary ALL cells. Furthermore, ALL cells were treated with a vascular endothelial growth factor (VEGF) inhibitor to block neuronal development and assess changes in the co-DEGs.

Results

We identified 216, 208, and 204 DEGs in ALL CNS metastasis specimens and neuronal development samples (GSE60926 and GSE13715). CD2, CD3G, CD3D, and LCK may be implicated in ALL CNS metastasis. LAMB1, MATN3, IGFBP3, LGALS1, and NEUROD1 may be associated with neuronal development. Specifically, four co-DEGs (LGALS1, TMEM71, SHISA2, and S100A11) may link ALL central nervous system metastasis and neuronal development process. The miRNAs for each co-DEG could be potential biomarkers or therapeutic targets for ALL central nervous system metastasis, especially hsa-miR-22-3p, hsa-miR-548t-5p, and hsa-miR-6134. Additionally, four co-DEGs (LGALS1, TMEM71, SHISA2, and S100A11) were validated in CNS-infiltrated ALL cells. The VEGF inhibitor demonstrated a suppressive effect on mRNA and protein expression of key co-DEGs.

Conclusion

The bioinformatic survey and key gene validation suggest a possible correlation between ALL CNS metastasis and the neuronal development process. Simulating the neuronal development process might be a possible strategy for CNS metastasis in ALL. LGALS1, TMEM71, SHISA2, and S100A11 genes are promising and novel biomarkers and targets in ALL CNS metastasis.

Intravital microscopy visualizes innate immune crosstalk and function in tissue microenvironment

Significant advances have been made in the field of intravital microscopy (IVM) on myeloid cells due to the growing number of validated fluorescent probes and reporter mice. IVM provides a visualization platform to directly observe cell behavior and deepen our understanding of cellular dynamics, heterogeneity, plasticity, and cell-cell communication in native tissue environments. This review outlines the current studies on the dynamic interaction and function of innate immune cells with a focus on those that are studied with IVM and covers the advances in data analysis with emerging artificial intelligence-based algorithms. Finally, the prospects of IVM on innate immune cells are discussed.

Targeting cytohesin-1 suppresses acute myeloid leukemia progression and overcomes resistance to ABT-199

Adhesion molecules play essential roles in the homeostatic regulation and malignant transformation of hematopoietic cells. The dysregulated expression of adhesion molecules in leukemic cells accelerates disease progression and the development of drug resistance. Thus, targeting adhesion molecules represents an attractive anti-leukemic therapeutic strategy. In this study, we investigated the prognostic role and functional significance of cytohesin-1 (CYTH1) in acute myeloid leukemia (AML). Analysis of AML patient data from the GEPIA and BloodSpot databases revealed that CYTH1 was significantly overexpressed in AML and independently correlated with prognosis. Functional assays using AML cell lines and an AML xenograft mouse model confirmed that CYTH1 depletion significantly inhibited the adhesion, migration, homing, and engraftment of leukemic cells, delaying disease progression and prolonging animal survival. The CYTH1 inhibitor SecinH3 exerted in vitro and in vivo anti-leukemic effects by disrupting leukemic adhesion and survival programs. In line with the CYTH1 knockdown results, targeting CYTH1 by SecinH3 suppressed integrin-associated adhesion signaling by reducing ITGB2 expression. SecinH3 treatment efficiently induced the apoptosis and inhibited the growth of a panel of AML cell lines (MOLM-13, MV4-11 and THP-1) with mixed-lineage leukemia gene rearrangement, partly by reducing the expression of the anti-apoptotic protein MCL1. Moreover, we showed that SecinH3 synergized with the BCL2-selective inhibitor ABT-199 (venetoclax) to inhibit the proliferation and promote the apoptosis of ABT-199-resistant leukemic cells. Taken together, our results not only shed light on the role of CYTH1 in cell-adhesion-mediated leukemogenesis but also propose a novel combination treatment strategy for AML.

Transcranial photobiomodulation improves insulin therapy in diabetic microglial reactivity and the brain drainage system

The dysfunction of microglia in the development of diabetes is associated with various diabetic complications, while traditional insulin therapy is insufficient to rapidly restore the function of microglia. Therefore, the search for new alternative methods of treating diabetes-related dysfunction of microglia is urgently needed. Here, we evaluate the effects of transcranial photobiomodulation (tPBM) on microglial function in diabetic mice and investigate its mechanism. We find tPBM treatment effectively improves insulin therapy on microglial morphology and reactivity. We also show that tPBM stimulates brain drainage system through activation of meningeal lymphatics, which contributes to the removal of inflammatory factor, and increase of microglial purinergic receptor P2RY12. Besides, the energy expenditure and locomotor activity of diabetic mice are also improved by tPBM. Our results demonstrate that tPBM can be an efficient, non-invasive method for the treatment of microglial dysfunction caused by diabetes, and also has the potential to prevent diabetic physiological disorders.

Impact of central nervous system involvement in adult patients with Philadelphia-negative acute lymphoblastic leukemia: a GRAALL-2005 study

Whereas the prognosis of adult patients with Philadelphia-negative acute lymphoblastic leukemia (ALL) has greatly improved since the advent of pediatric-inspired regimens, the impact of initial central nervous system (CNS) involvement has not been formerly re-evaluated. We report here the outcome of patients with initial CNS involvement included in the pediatric-inspired prospective randomized GRAALL-2005 study. Between 2006 and 2014, 784 adult patients (aged 18-59 years) with newly diagnosed Philadelphia-negative ALL were included, of whom 55 (7%) had CNS involvement. In CNSpositive patients, overall survival was shorter (median 1.9 years vs. not reached, HR=1.8 [1.3-2.6], P<0.001). While there was no statistical difference in cumulative incidence of relapse between CNS+ and CNS- patients (HR=1.5 [0.9-2.5], P=0.11), non-relapse mortality was significantly higher in those with initial CNS disease (HR=2.1 [1.2-3.5], P=0.01). This increase in toxicity was mostly observed in patients randomized to the high-dose cyclophosphamide arm and in those who received allogeneic stem cell transplantation. Exploratory landmark analyses did not show any association between either cranial irradiation or allogeneic stem cell transplantation and outcome. Despite improved outcome in young adult ALL patients with pediatric-inspired protocols, CNS involvement is associated with a worse outcome mainly due to excess toxicity, without improved outcome with allogeneic SCT.

Skull bone marrow channels as immune gateways to the central nervous system

Decades of research have characterized diverse immune cells surveilling the CNS. More recently, the discovery of osseous channels (so-called 'skull channels') connecting the meninges with the skull and vertebral bone marrow has revealed a new layer of complexity in our understanding of neuroimmune interactions. Here we discuss our current understanding of skull and vertebral bone marrow anatomy, its contribution of leukocytes to the meninges, and its surveillance of the CNS. We explore the role of this hematopoietic output on CNS health, focusing on the supply of immune cells during health and disease.

PPARG, GNG12, and CD19 are potential independent predictors of central nerve recurrence in childhood acute lymphoblastic leukemia

OBJECTIVE

To identify biomarkers that can predict the recurrence of the central nervous system (CNS) in children with acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

The transcriptome and clinical data of ALL in children were downloaded from the TARGET database. Transcriptome data were analyzed by bioinformatics method to identify core (hub) genes and establish a risk assessment model. Univariate Cox analysis was performed on each clinical data, and multivariate Cox regression analysis was performed on the obtained results and risk score. The children ALL phase I samples from TARGET database were used for validation.

RESULTS

Univariate multivariate Cox analysis of 10 hub genes identified showed that PPARG (HR = 0.78, 95%CI = 0.67-0.91, p = 0.007), CD19 (HR = 1.15, 95%CI = 1.05-1.26, p = 0.003) and GNG12 (HR = 1.25, 95%CI = 1.04-1.51, p = 0.017) had statistical differences. The risk score was statistically significant in univariate (HR = 3.06, 95%CI = 1.30-7.19, p = 0.011) and multivariate (HR = 1.81, 95%CI = 1.16-2.32, p = 0.046) Cox regression analysis. The survival analysis results of the high and low-risk groups were different when the validation dataset was substituted into the model (p = 0.018). Then, we constructed a Nomogram which had a concordance index of survival prediction of 0.791(95%CI= 0.779-0.803). In addition, the CNS involvement grading status at first diagnosis CNS3 vs. CNS1 (HR = 5.74, 95%CI = 2.01-16.4, p = 0.001), T cell vs B cell (HR = 1.63, 95% CI = 1.06-2.49, p = 0.026) were also statistically significant.

CONCLUSIONS

PPARG, GNG12, and CD19 may be predictors of CNS relapse in childhood ALL.

An optical clearing imaging window: Realization of mouse brain imaging and manipulation through scalp and skull

Cortical visualization is essential to understand the dynamic changes in brain microenvironment under physiopathological conditions. However, the turbid scalp and skull severely limit the imaging depth and resolution. Existing cranial windows require invasive scalp excision and various subsequent skull treatments. Non-invasive in vivo imaging of skull bone marrow, meninges, and cortex through scalp and skull with high resolution yet remains a challenge. In this work, a non-invasive trans-scalp/skull optical clearing imaging window is proposed for cortical and calvarial imaging, which is achieved by applying a novel skin optical clearing reagent. The imaging depth and resolution are greatly enhanced in near infrared imaging and optical coherence tomography imaging. Combining this imaging window with adaptive optics, we achieve the visualization and manipulation of the calvarial and cortical microenvironment through the scalp and skull using two-photon imaging for the first time. Our method provides a well-performed imaging window and paves the way for intravital brain studies with the advantages of easy-operation, convenience and non-invasiveness.

Type 2 immunity in the brain and brain borders

Recent research in neuroimmunology has revolutionized our understanding of the intricate interactions between the immune system and the central nervous system (CNS). The CNS, an "immune-privileged organ", is now known to be intimately connected to the immune system through different cell types and cytokines. While type 2 immune responses have traditionally been associated with allergy and parasitic infections, emerging evidence suggests that these responses also play a crucial role in CNS homeostasis and disease pathogenesis. Type 2 immunity encompasses a delicate interplay among stroma, Th2 cells, innate lymphoid type 2 cells (ILC2s), mast cells, basophils, and the cytokines interleukin (IL)-4, IL-5, IL-13, IL-25, TSLP and IL-33. In this review, we discuss the beneficial and detrimental roles of type 2 immune cells and cytokines in CNS injury and homeostasis, cognition, and diseases such as tumors, Alzheimer's disease and multiple sclerosis.

Histopathological changes of the dural myeloid cells and lymphatic vessels in a mouse model of sepsis-associated encephalopathy

As a common diffuse encephalopathy caused by sepsis, sepsis-associated encephalopathy (SAE) is closely associated with increased mortality, severe cognition dysfunction and increased cost of health care in patients of sepsis. Accumulating evidence suggests that the dura mater, the outermost meninges of the central nervous system (CNS), plays an important role in CNS immunity, especially with the discovery of meningeal lymphatic vessels (mLVs), as well as a plentiful array of resident or infiltrating immune cells harbored in the dura. Although these findings have significantly enhanced our understanding of the immune function of dura under both steady-state and pathological condition of CNS, whether and how the immune cells and mLVs within dura response to SAE still remains largely unexplored. Here, we established lipopolysaccharide (LPS) intraperitoneal injection-induced SAE model and examined the dural resident immune cells and mLVs. We analysed the histological change in dura by performing hematoxylin and eosin (H&E) and immunofluorescence staining. Results showed that systemic exposure to LPS induced neutrophils recruitment, exudation and gathering around the dural blood vessels. Moreover, resident macrophage altered its shape as well as location, and downregulated major histocompatibility (MHC) class II expression following LPS injection. We also found that LPS exposure induced dorsal meningeal lymphangiogenesis. Together, these findings collectively demonstrated that LPS-induced SAE can stimulate immune cells and mLVs within dura and provided more information about the immune response of the dura in sepsis.

The origin of brain malignancies at the blood-brain barrier

Despite improvements in extracranial therapy, survival rate for patients suffering from brain metastases remains very poor. This is coupled with the incidence of brain metastases continuing to rise. In this review, we focus on core contributions of the blood-brain barrier to the origin of brain metastases. We first provide an overview of the structure and function of the blood-brain barrier under physiological conditions. Next, we discuss the emerging idea of a pre-metastatic niche, namely that secreted factors and extracellular vesicles from a primary tumor site are able to travel through the circulation and prime the neurovasculature for metastatic invasion. We then consider the neurotropic mechanisms that circulating tumor cells possess or develop that facilitate disruption of the blood-brain barrier and survival in the brain's parenchyma. Finally, we compare and contrast brain metastases at the blood-brain barrier to the primary brain tumor, glioma, examining the process of vessel co-option that favors the survival and outgrowth of brain malignancies.

Systemic inflammation, neuroinflammation and perioperative neurocognitive disorders

Perioperative neurocognitive disorder (PND) is a common disorder following anesthesia and surgery, especially in the elderly. The complex cellular and molecular processes are involved in PND, but the underlying pathogenesis of which remains inconclusive due to conflicting data. A growing body of evidence has been shown that perioperative systemic inflammation plays important roles in the development of PND. We reviewed the relevant literature retrieved by a search in the PubMed database (on July 20, 2023). The search terms used were "delirium", "post operative cognitive dysfunction", "perioperative neurocognitive disorder", "inflammation" and "systemic", alone and in combination. All articles identified were English-language, full-text papers. The ones cited in the review are those that make a substantial contribution to the knowledge about systemic inflammation and PNDs. The aim of this review is to bring together the latest evidence for the understanding of how perioperative systemic inflammation mediates neuroinflammation and brain injury, how the inflammation is regulated and how we can translate these findings into prevention and/or treatment for PND.

The calvaria stands alone: Unique aspects of the skull bone marrow-meninges border

Channels connecting the skull bone marrow and the meninges have recently been discovered as a path for immune cell and molecule trafficking. In this issue of Cell, Kolabas, Kuemmerle, Perneczky, Förstera, and colleagues characterize these channels in humans and mice, revealing unique features of skull bone marrow and localized activation in human pathology.

Meningeal T cells function in the central nervous system homeostasis and neurodegenerative diseases

Recently, a rising interest is given to neuroimmune communication in physiological and neuropathological conditions. Meningeal immunity is a complex immune environment housing different types of immune cells. Here, we focus on meningeal T cells, possibly the most explored aspect of neuro-immune cell interactions. Emerging data have shown that meningeal T cells play a crucial role in the pathogenesis of several neurodegenerative disorders, including multiple sclerosis, Alzheimer's, Parkinson's, and Huntington's diseases. This review highlights how meningeal T cells may contribute to immune surveillance of the central nervous system (CNS) and regulate neurobehavioral functions through the secretion of cytokines. Overall, this review assesses the recent knowledge of meningeal T cells and their effects on CNS functioning in both health and disease conditions and the underlying mechanisms.

Pathological angiogenesis: mechanisms and therapeutic strategies

In multicellular organisms, angiogenesis, the formation of new blood vessels from pre-existing ones, is an essential process for growth and development. Different mechanisms such as vasculogenesis, sprouting, intussusceptive, and coalescent angiogenesis, as well as vessel co-option, vasculogenic mimicry and lymphangiogenesis, underlie the formation of new vasculature. In many pathological conditions, such as cancer, atherosclerosis, arthritis, psoriasis, endometriosis, obesity and SARS-CoV-2(COVID-19), developmental angiogenic processes are recapitulated, but are often done so without the normal feedback mechanisms that regulate the ordinary spatial and temporal patterns of blood vessel formation. Thus, pathological angiogenesis presents new challenges yet new opportunities for the design of vascular-directed therapies. Here, we provide an overview of recent insights into blood vessel development and highlight novel therapeutic strategies that promote or inhibit the process of angiogenesis to stabilize, reverse, or even halt disease progression. In our review, we will also explore several additional aspects (the angiogenic switch, hypoxia, angiocrine signals, endothelial plasticity, vessel normalization, and endothelial cell anergy) that operate in parallel to canonical angiogenesis mechanisms and speculate how these processes may also be targeted with anti-angiogenic or vascular-directed therapies.

Age-dependent immune and lymphatic responses after spinal cord injury

Spinal cord injury (SCI) causes lifelong debilitating conditions. Previous works demonstrated the essential role of the immune system in recovery after SCI. Here, we explored the temporal changes of the response after SCI in young and aged mice in order to characterize multiple immune populations within the mammalian spinal cord. We revealed substantial infiltration of myeloid cells to the spinal cord in young animals, accompanied by changes in the activation state of microglia. In contrast, both processes were blunted in aged mice. Interestingly, we discovered the formation of meningeal lymphatic structures above the lesion site, and their role has not been examined after contusive injury. Our transcriptomic data predicted lymphangiogenic signaling between myeloid cells in the spinal cord and lymphatic endothelial cells (LECs) in the meninges after SCI. Together, our findings delineate how aging affects the immune response following SCI and highlight the participation of the spinal cord meninges in supporting vascular repair.

Regulation and Functions of α6-Integrin (CD49f) in Cancer Biology

Over the past decades, our knowledge of integrins has evolved from being understood as simple cell surface adhesion molecules to receptors that have a complex range of intracellular and extracellular functions, such as delivering chemical and mechanical signals to cells. Consequently, they actively control cellular proliferation, differentiation, and apoptosis. Dysregulation of integrin signaling is a major factor in the development and progression of many tumors. Many reviews have covered the broader integrin family in molecular and cellular studies and its roles in diseases. Nevertheless, further understanding of the mechanisms specific to an individual subunit of different heterodimers is more useful. Thus, we describe the current understanding of and exploratory investigations on the α6-integrin subunit (CD49f, VLA6; encoded by the gene itga6) in normal and cancer cells. The roles of ITGA6 in cell adhesion, stemness, metastasis, angiogenesis, and drug resistance, and as a diagnosis biomarker, are discussed. The role of ITGA6 differs based on several features, such as cell background, cancer type, and post-transcriptional alterations. In addition, exosomal ITGA6 also implies metastatic organotropism. The importance of ITGA6 in the progression of a number of cancers, including hematological malignancies, suggests its potential usage as a novel prognostic or diagnostic marker and useful therapeutic target for better clinical outcomes.

Diagnosis and management of adult central nervous system leukemia

Central nervous system leukemia (CNSL) is a prominent infiltration reason for therapy failing in acute leukemia. Recurrence rates and the prognosis have alleviated with current prophylactic regimens. However, the accurate stratification of relapse risk and treatment regimens for relapsed or refractory patients remain clinical challenges yet to be solved. Recently, with hematopoietic stem cell transplantation (HSCT) and chimeric antigen receptor-T (CAR-T) cellular therapy showing encouraging effects in some CNSL patients, advances in treating CNSL have already been reported. The development of molecular targeted agents as well as antibody-based drugs will provide patients with more personalized treatment. This article summarized recent research developments about risk factors, diagnosis, prevention, and treatment in adults with CNSL.

MRI manifestations of central nervous system leukaemia and cytological analysis of the cerebrospinal fluid

AIM

To investigate the magnetic resonance imaging (MRI) features and explore the value of MRI in the diagnosis of central nervous system leukaemia (CNSL).

MATERIALS AND METHODS

A retrospective study was performed in 68 patients with leukaemia who underwent cranial MRI between January 2020 and June 2022 at Institute of Hematology and Blood Diseases Hospital.

RESULTS

A total of 33 patients fulfilled the requirements for inclusion. The findings showed that 87.9% patients exhibited neurological symptoms, and 23 patients showed abnormal MRI findings. No differences were observed between the MRI+ and MRI- groups in terms of age, sex, neurological symptoms, glucose in the cerebrospinal fluid (CSF), chloride in the CSF, abnormal cells detected using conventional cytology (CC), bone marrow status at the diagnosis of CNSL, signal intensity ratio, and mortality, except for protein concentration and the number of leukaemic cells detected using flow cytometry (FCM) in the CSF. Kaplan-Meier survival analysis in patients with leukaemia revealed no statistical differences in the median survival times between the MRI+ group and MRI- group. Cox regression analysis and multivariate analysis showed no significant difference in survival rate between the MRI+ and MRI- groups. Kappa consistency test shows weak diagnostic consistency between MRI and CC, and weak diagnostic inconsistency between MRI and FCM.

CONCLUSION

MRI could serve as an important complementary tool to CC and FCM in the diagnosis of CNSL, especially in patients without leptomeningeal involvement.

The Neurovasculome: Key Roles in Brain Health and Cognitive Impairment: A Scientific Statement From the American Heart Association/American Stroke Association

BACKGROUND

Preservation of brain health has emerged as a leading public health priority for the aging world population. Advances in neurovascular biology have revealed an intricate relationship among brain cells, meninges, and the hematic and lymphatic vasculature (the neurovasculome) that is highly relevant to the maintenance of cognitive function. In this scientific statement, a multidisciplinary team of experts examines these advances, assesses their relevance to brain health and disease, identifies knowledge gaps, and provides future directions.

METHODS

Authors with relevant expertise were selected in accordance with the American Heart Association conflict-of-interest management policy. They were assigned topics pertaining to their areas of expertise, reviewed the literature, and summarized the available data.

RESULTS

The neurovasculome, composed of extracranial, intracranial, and meningeal vessels, as well as lymphatics and associated cells, subserves critical homeostatic functions vital for brain health. These include delivering O2 and nutrients through blood flow and regulating immune trafficking, as well as clearing pathogenic proteins through perivascular spaces and dural lymphatics. Single-cell omics technologies have unveiled an unprecedented molecular heterogeneity in the cellular components of the neurovasculome and have identified novel reciprocal interactions with brain cells. The evidence suggests a previously unappreciated diversity of the pathogenic mechanisms by which disruption of the neurovasculome contributes to cognitive dysfunction in neurovascular and neurodegenerative diseases, providing new opportunities for the prevention, recognition, and treatment of these conditions.

CONCLUSIONS

These advances shed new light on the symbiotic relationship between the brain and its vessels and promise to provide new diagnostic and therapeutic approaches for brain disorders associated with cognitive dysfunction.

Immune compartments at the brain's borders in health and neurovascular diseases

Recent evidence implicates cranial border immune compartments in the meninges, choroid plexus, circumventricular organs, and skull bone marrow in several neuroinflammatory and neoplastic diseases. Their pathogenic importance has also been described for cardiovascular diseases such as hypertension and stroke. In this review, we will examine the cellular composition of these cranial border immune niches, the potential pathways through which they might interact, and the evidence linking them to cardiovascular disease.

CXCR4 antagonists disrupt leukaemia-meningeal cell adhesion and attenuate chemoresistance

The effective prophylaxis and treatment of central nervous system (CNS) involvement in acute lymphoblastic leukaemia (ALL) remains a significant clinical challenge. Developing novel and more effective CNS-directed therapies has been hampered, in part, by our limited understanding of the leukaemia niche in the CNS relative to the bone marrow. Accordingly, defining the molecular and cellular components critical for the establishment and maintenance of the CNS leukaemia niche may lead to new therapeutic opportunities. In prior work we showed that direct intercellular interactions between leukaemia and meningeal cells enhance leukaemia chemoresistance in the CNS. Herein, we show that the CXCR4/CXCL12 chemokine axis contributes to leukaemia-meningeal cell adhesion. Importantly, clinically tested CXCR4 antagonists, which are likely to cross the blood-brain and blood-cerebral spinal fluid barriers and penetrate the CNS, effectively disrupted leukaemia-meningeal cell adhesion. Moreover, by disrupting these intercellular interactions, CXCR4 antagonists attenuated leukaemia chemoresistance in leukaemia-meningeal cell co-culture experiments and enhanced the efficacy of cytarabine in targeting leukaemia cells in the meninges in vivo. This work identifies the CXCR4/CXCL12 axis as an important regulator of intercellular interactions within the CNS leukaemia niche and supports further testing of the therapeutic efficacy of CXCR4 antagonists in overcoming CNS niche-mediated chemoresistance.

Integrins and the Metastasis-like Dissemination of Acute Lymphoblastic Leukemia to the Central Nervous System

Acute lymphoblastic leukemia (ALL) disseminates with high prevalence to the central nervous system (CNS) in a process resembling aspects of the CNS surveillance of normal immune cells as well as aspects of brain metastasis from solid cancers. Importantly, inside the CNS, the ALL blasts are typically confined within the cerebrospinal fluid (CSF)-filled cavities of the subarachnoid space, which they use as a sanctuary protected from both chemotherapy and immune cells. At present, high cumulative doses of intrathecal chemotherapy are administered to patients, but this is associated with neurotoxicity and CNS relapse still occurs. Thus, it is imperative to identify markers and novel therapy targets specific to CNS ALL. Integrins represent a family of adhesion molecules involved in cell-cell and cell-matrix interactions, implicated in the adhesion and migration of metastatic cancer cells, normal immune cells, and leukemic blasts. The ability of integrins to also facilitate cell-adhesion mediated drug resistance, combined with recent discoveries of integrin-dependent routes of leukemic cells into the CNS, have sparked a renewed interest in integrins as markers and therapeutic targets in CNS leukemia. Here, we review the roles of integrins in CNS surveillance by normal lymphocytes, dissemination to the CNS by ALL cells, and brain metastasis from solid cancers. Furthermore, we discuss whether ALL dissemination to the CNS abides by known hallmarks of metastasis, and the potential roles of integrins in this context.

How I prevent and treat central nervous system disease in adults with acute lymphoblastic leukemia

The central nervous system (CNS) is the most important site of extramedullary disease in adults with acute lymphoblastic leukemia (ALL). Although CNS disease is identified only in a minority of patients at the time of diagnosis, subsequent CNS relapses (either isolated or concurrent with other sites) occur in some patients even after the delivery of prophylactic therapy targeted to the CNS. Historically, prophylaxis against CNS disease has included intrathecal (IT) chemotherapy and radiotherapy (RT), although the latter is being used with decreasing frequency. Treatment of a CNS relapse usually involves intensive systemic therapy and cranial or craniospinal RT along with IT therapy and consideration of allogeneic hematopoietic cell transplant. However, short- and long-term toxicities can make these interventions prohibitively risky, particularly for older adults. As new antibody-based immunotherapy agents have been approved for relapsed/refractory B-cell ALL, their use specifically for patients with CNS disease is an area of keen interest not only because of the potential for efficacy but also concerns of unique toxicity to the CNS. In this review, we discuss data-driven approaches for these common and challenging clinical scenarios as well as highlight how recent findings potentially support the use of novel immunotherapeutic strategies for CNS disease.

Glymphatic system dysfunction in pediatric acute lymphoblastic leukemia without clinically diagnosed central nervous system infiltration: a novel DTI-ALPS method

BACKGROUND AND OBJECTIVE

Central nervous system (CNS) infiltration commonly occurs in children with acute lymphoblastic leukemia (ALL). Nevertheless, CNS infiltration is rarely detected at the initial diagnosis. The glymphatic system, which regulates cerebrospinal fluid (CSF) and interstitial fluid transport, is considered one of the possible routes of CNS infiltration by leukemia cells. In this study, we used diffusion tensor image analysis along the perivascular space (DTI-ALPS) method to investigate glymphatic system function and obtained CSF volume using synthetic magnetic resonance imaging (SyMRI) in pediatric ALL without clinically diagnosed CNS infiltration.

MATERIALS AND METHODS

Twenty-nine ALL and 29 typically developing (TD) children were prospectively recruited (age 4-16 years) in the present study. Group differences in brain volumetric parameters, brain water diffusivities, and the ALPS index were evaluated after controlling for age, gender, and handedness. Furthermore, significant group-different parameters were correlated with clinical information using partial correlations analysis.

RESULTS

Lower Dxassoc and ALPS index, and increased CSF volume were found in pediatric ALL (all p_{FDR-corrected} < 0.05). Moreover, the ALPS index was negatively associated with the risk classification (r =  - 0.59, p_{FDR-corrected} = 0.04) in pediatric ALL.

CONCLUSIONS

Dysfunction of the glymphatic system and accumulation of CSF were presented in pediatric ALL without clinically diagnosed CNS infiltration. These novel findings suggested that the glymphatic system might be essential in the early-stage process of ALL CNS infiltration, which provides a new direction for exploring underlying mechanisms and early detection of pediatric ALL CNS infiltration.

KEY POINTS

• Lower Dxassoc and ALPS index, and increased CSF volume were found in pediatric ALL (all p_{FDR-corrected} < 0.05). • The ALPS index was negatively associated with the risk classification (r =  -0.59, p_{FDR-corrected} = 0.04) in pediatric ALL. • Dysfunction of the glymphatic system and accumulation of CSF were presented in pediatric ALL without clinically diagnosed CNS infiltration, which suggested that the ALPS index and CSF volume might be promising imaging markers for early detection of pediatric ALL CNS infiltration.

Role of Fyn in hematological malignancies

BACKGROUND

Tyrosine kinase Fyn is a member of the Src family of kinases. In addition to the wild type, three mRNA splice isoforms of Fyn have been identified; Fyn-B, Fyn-T, and Fyn-C. Fyn-T is highly expressed in T lymphocytes, and its expression level is significantly higher in mature T cells than in immature T cells. The abnormal expression of Fyn is closely related to the metabolism, proliferation, and migration of tumor cells. Recent studies have shown that Fyn is expressed in a variety of tumor tissues, and its expression and function vary among different tumors. In some tumors, Fyn acts as a pro-oncogene to promote tumor proliferation and metastasis. Moreover, Fyn mutations have been detected in many hematological tumors in recent years, suggesting a critical regulatory role of Fyn in the development of malignancies.

METHODS

This review analyzed the relevant literature in PubMed and other databases.

PURPOSE

The aim of this study was to systemically review recent research findings on various aspects of Fyn in the pathogenesis and treatment of different types of hematological malignancies and suggests possible future research directions for targeted tumor therapy.

CONCLUSION

Fyn could be a novel prognostic marker and therapeutic target. Treatment option targeting Fyn might be beneficial for future studies.

Quantitative IVIM parameters evaluating perfusion changes in brain parenchyma in patients newly diagnosed with acute leukemia: Compared with healthy participants

Purpose

To study the value of quantitative IVIM parameters in evaluating cerebral blood perfusion changes in patients newly diagnosed with acute leukemia (AL) by comparing them with healthy participants.

Materials and methods

This prospective study consecutively recruited 49 participants with newly diagnosed AL and 40 normal controls between July 2020 and September 2022. All participants underwent an MRI of the brain using an axial T₁-weighted and an IVIM sequence. The IVIM parameters (water diffusion coefficient, sADC, pseudoperfusion fraction, f; diffusion coefficient, D, pseudodiffusion coefficient, D ^*, and perfusion-diffusion ratio, PDR) and peripheral white blood cell (WBC) counts were obtained. An unpaired t-test or the Mann-Whitney U-test was performed to compare the differences in gray matter (GM) and white matter (WM) of healthy participants and AL patients and the differences in IVIM parameters between healthy participants and patients with AL. In addition, multivariate (logistic regression) analyses were used to identify independent predictors and then, the receiver operating characteristic curve (ROC) analyses were performed.

Results

40 healthy participants and 49 patients with newly diagnosed AL were evaluated. In healthy participants, sADC, PDR, D and f values of GM were significantly higher than those of WM (t = 5.844, t = 3.838, t = 7.711, z = -2.184, respectively, all P < 0.05). In AL patients, the D, f and sADC values of GM were significantly higher than those of WM (t = 3.450, t = 6.262, t = 4.053, respectively, all P < 0.05). The sADC and f value from AL patients were significantly lower than those from healthy participants in GM (z = -2.537, P = 0.011; and z = -2.583, P = 0.010, respectively) and WM (z = -2.969, P = 0.003; z = -2.923, P = 0.003, respectively). The WBC counts of AL patients were significantly higher than those of healthy participants (t = 3.147, P = 0.002). Multivariate analyses showed that the f values of GM and WM were independent predictors of AL (P = 0.030, and 0.010, respectively), with the optimal cut-off value at 7.08% (AUC ROC curve: 0.661, specificity: 11.4%, sensitivity: 98%) and 13.77% (AUC ROC curve: 0.682, specificity: 79.5%, sensitivity: 59.2%).

Conclusion

The IVIM parameters of brain parenchyma in patients newly diagnosed with AL differed from those of the healthy participants. The changes of cerebral blood flow perfusion are expected to provide new ideas for studying central nervous system infiltration in AL.

Fluid dynamics in aging-related dementias

Recent human and animal model experimental studies revealed novel pathways for fluid movement, immune cell trafficking and metabolic waste clearance in CNS. These studies raise the intriguing possibility that the newly discovered pathways, including the glymphatic system, lymphatic meningeal vessels and skull-brain communication channels, are impaired in aging and neurovascular and neurodegenerative diseases associated with dementia, including Alzheimer's disease (AD) and AD-related dementia. We provide an overview of the glymphatic and dural meningeal lymphatic systems, review current methods and approaches used to study glymphatic flow in humans and animals, and discuss current evidence and controversies related to its role in CNS flow homeostasis under physiological and pathophysiological conditions. Non-invasive imaging approaches are needed to fully understand the mechanisms and pathways driving fluid movement in CNS and their roles across lifespan including healthy aging and aging-related dementia.

Characterisation of children and adolescents with acute lymphoblastic leukaemia who presented without peripheral blood blasts at diagnosis

Of 1003 children with acute lymphoblastic leukaemia (ALL), 147 (14.7%) presented without peripheral blood blasts (PBB). While absence of PBB was not independently associated with survival outcomes when compared to those with PBB, patients without PBB had distinct genetic and clinical characteristics. Notably, we identified a novel genotype-phenotype relationship, in that the patients without PBB had a significantly higher incidence of hyperdiploid B-ALL, accounting for almost half of all patients without PBB (46.9% vs. 22.7%, p < 0.001). Further, absence of PBB was associated with decreased rates of leukaemia involvement of the central nervous system (p < 0.001).

Customizing delivery nano-vehicles for precise brain tumor therapy

Although some tumor has become a curable disease for many patients, involvement of the central nervous system (CNS) is still a major concern. The blood-brain barrier (BBB), a special structure in the CNS, protects the brain from bloodborne pathogens via its excellent barrier properties and hinders new drug development for brain tumor. Recent breakthroughs in nanotechnology have resulted in various nanovehicless (NPs) as drug carriers to cross the BBB by different strategys. Here, the complex compositions and special characteristics of causes of brain tumor formation and BBB are elucidated exhaustively. Additionally, versatile drug nanovehicles with their recent applications and their pathways on different drug delivery strategies to overcome the BBB obstacle for anti-brain tumor are briefly discussed. Customizing nanoparticles for brain tumor treatments is proposed to improve the efficacy of brain tumor treatments via drug delivery from the gut to the brain. This review provides a broad perspective on customizing delivery nano-vehicles characteristics facilitate drug distribution across the brain and pave the way for the creation of innovative nanotechnology-based nanomaterials for brain tumor treatments.

Single-cell analysis of acute lymphoblastic and lineage-ambiguous leukemia: approaches and molecular insights

Despite recent progress in identifying the genetic drivers of acute lymphoblastic leukemia (ALL), prognosis remains poor for those individuals who experience disease recurrence. Moreover, acute leukemias of ambiguous lineage lack a biologically informed framework to guide classification and therapy. These needs have driven the adoption of multiple complementary single-cell sequencing approaches to explore key issues in the biology of these leukemias, including cell of origin, developmental hierarchy and ontogeny, and the molecular heterogeneity driving pathogenesis, progression, and therapeutic responsiveness. There are multiple single-cell techniques for profiling a specific modality, including RNA, DNA, chromatin accessibility and methylation; and an expanding range of approaches for simultaneous analysis of multiple modalities. Single-cell sequencing approaches have also enabled characterization of cell-intrinsic and -extrinsic features of ALL biology. In this review we describe these approaches and highlight the extensive heterogeneity that underpins ALL gene expression, cellular differentiation, and clonal architecture throughout disease pathogenesis and treatment resistance. In addition, we discuss the importance of the dynamic interactions that occur between leukemia cells and the nonleukemia microenvironment. We discuss potential opportunities and limitations of single-cell sequencing for the study of ALL biology and treatment responsiveness.

Leveraging Molecular and Immune-Based Therapies in Leptomeningeal Metastases

Leptomeningeal metastases represent an aggressive stage of cancer with few durable treatment options. Improved understanding of cancer biology, neoplastic reliance on oncogenic driver mutations, and complex immune system interactions have resulted in an explosion in cancer-directed therapy in the last two decades to include small molecule inhibitors and immune checkpoint inhibitors. Most of these therapeutics are underexplored in patients with leptomeningeal metastases, limiting extrapolation of extracranial and even intracranial efficacy outcomes to the unique leptomeningeal space. Further confounding our interpretation of drug activity in the leptomeninges is an incomplete understanding of drug penetration through the blood-cerebrospinal fluid barrier of the choroid plexus. Nevertheless, a number of retrospective studies and promising prospective trials provide evidence of leptomeningeal activity of several small molecule and immune checkpoint inhibitors and underscore potential areas of further therapeutic development for patients harboring leptomeningeal disease.

Monitoring Angiotropic Extravascular Migratory Metastasis In Vitro

The mechanism of cancer cell migration from the primary tumor toward secondary sites is not fully understood. In addition to intravascular cellular migration, angiotropic extravascular migratory metastasis (EVMM) has been recognized as a metastatic pathway involving tumor cells crawling along the abluminal vascular surface to distant sites. A very simple in vitro 3D assay is described here, which is based on a previous in vitro angiogenesis assay. The assay involves monitoring single fluorescence-tagged migrating cancer cells in the presence of vascular structures in real time. This coculture assay represents a quantitative approach for monitoring the migration processes of cancer cells along vessels, demonstrating phenotypic switching and migration dynamics. This protocol can be used for molecular analyses and can also be adapted for screening of therapeutic agents to block cancer metastasis.

Regulation of Kinase Signaling Pathways by α6β4-Integrins and Plectin in Prostate Cancer

Hemidesmosomes (HDs) are adhesive structures that ensure stable anchorage of cells to the basement membrane. They are formed by α6β4-integrin heterodimers and linked to intermediate filaments via plectin. It has been reported that one of the most common events during the pathogenesis of prostate cancer (PCa) is the loss of HD organization. While the expression levels of β4-integrins are strongly reduced, the expression levels of α6-integrins and plectin are maintained or even elevated, and seem to promote tumorigenic properties of PCa cells, such as proliferation, invasion, metastasis, apoptosis- and drug-resistance. In this review, we discuss the potential mechanisms of how HD components might contribute to various cellular signaling pathways to promote prostate carcinogenesis. Moreover, we summarize the current knowledge on the involvement of α6β4-integrins and plectin in PCa initiation and progression.

Systematic analysis of brain and skull ischemic injury expression profiles reveals associations of the tumor immune microenvironment and cell death with ischemic stroke

Background

Previous studies have shown that stroke is a potential first sign of neoplasia, but the relationship between stroke and cancer remains unclear. As a complex brain disease, ischemic stroke involves cell death and immunity. Thus, it is necessary to investigate the association of the tumor immune microenvironment and cell death with ischemic stroke.

Methods

We established a photothrombosis-induced ischemic injury model in mouse brain and skull. Subsequently, we sequenced the whole transcriptome of the injured mouse brain and skull and analyzed the expression profiles. To investigate the association of stroke with cell death and cancer, we systematically performed gene set enrichment analysis in pan-cell death (i.e., apoptosis, cuproptosis, ferroptosis, necroptosis, and pyroptosis) and the cancer hallmark pathways. The time-dependent immune cell abundance variations after ischemic injury were estimated. Furthermore, pan-cancer genomic and prognostic analyses of the ischemic injury-related gene sets were also performed.

Results

In this study, we found that there exist temporal and spatial differences in the gene expression patterns of both the brain and skull with ischemic injury. The skull ischemic injury-induced changes in the brain transcriptome were particularly great, but could recover in a short period, while the skull transcriptome variation resulting from brain ischemic injury was long-lasting. In addition, the expression of the genes related to ischemic injury was also associated with pan-cell death and the cancer hallmark pathways. The changes in the abundance of immune cells indicate that brain ischemic injury may disrupt the immune microenvironment for a longer time, while the skull can balance the stability of the immune microenvironment better. Moreover, the brain ischemic injury-related gene sets were highly correlated with a variety of tumors, particularly glioblastoma multiforme (GBM), kidney renal clear cell carcinoma (KIRC), brain lower grade glioma (LGG), and uveal melanoma (UVM), which carry a greater mortality risk after stroke.

Conclusion

This systematic analysis not only helps in the understanding of the changes in the gene expression profiles of both the brain and skull with ischemic injury but also reveals the association of the tumor immune microenvironment and cell death with ischemic stroke.

Nanopore sequencing of clonal IGH rearrangements in cell-free DNA as a biomarker for acute lymphoblastic leukemia

Background

Acute Lymphoblastic Leukemia (ALL) is the most common pediatric cancer, and patients with relapsed ALL have a poor prognosis. Detection of ALL blasts remaining at the end of treatment, or minimal residual disease (MRD), and spread of ALL into the central nervous system (CNS) have prognostic importance in ALL. Current methods to detect MRD and CNS disease in ALL rely on the presence of ALL blasts in patient samples. Cell-free DNA, or small fragments of DNA released by cancer cells into patient biofluids, has emerged as a robust and sensitive biomarker to assess cancer burden, although cfDNA analysis has not previously been applied to ALL.

Methods

We present a simple and rapid workflow based on NanoporeMinION sequencing of PCR amplified B cell-specific rearrangement of the (IGH) locus in cfDNA from B-ALL patient samples. A cohort of 5 pediatric B-ALL patient samples was chosen for the study based on the MRD and CNS disease status.

Results

Quantitation of IGH-variable sequences in cfDNA allowed us to detect clonal heterogeneity and track the response of individual B-ALL clones throughout treatment. cfDNA was detected in patient biofluids with clinical diagnoses of MRD and CNS disease, and leukemic clones could be detected even when diagnostic cell-count thresholds for MRD were not met. These data suggest that cfDNA assays may be useful in detecting the presence of ALL in the patient, even when blasts are not physically present in the biofluid sample.

Conclusions

The Nanopore IGH detection workflow to monitor cell-free DNA is a simple, rapid, and inexpensive assay that may ultimately serve as a valuable complement to traditional clinical diagnostic approaches for ALL.