Disruption of blood-brain barrier (BBB) function is a key feature of cerebral malaria. Increased barrier permeability occurs due to disassembly of tight and adherens junctions between endothelial cells, yet the mechanisms governing junction disassembly and vascular permeability during cerebral malaria remain poorly characterized. We found that EphA2 is a principal receptor tyrosine kinase mediating BBB breakdown during Plasmodium infection. Upregulated on brain microvascular endothelial cells in response to inflammatory cytokines, EphA2 is required for the loss of junction proteins on mouse and human brain microvascular endothelial cells. Furthermore, EphA2 is necessary for CD8+ T cell brain infiltration and subsequent BBB breakdown in a mouse model of cerebral malaria. Blocking EphA2 protects against BBB breakdown highlighting EphA2 as a potential therapeutic target for cerebral malaria. Malaria is a disease caused by transmission of the mosquito-borne Plasmodium parasite that remains a severe global public health issue. Advancements in parasite control measures such as prevention, treatment, and surveillance have reduced the incidence of malaria worldwide. However, current reports indicate that progress towards reducing global malaria cases and deaths in recent years has stalled. Therefore, it is imperative that we continue to explore new therapeutic avenues that can synergize with existing treatment methods. In particular, there is currently no adjunctive treatment available for cerebral malaria which is a serious complication of Plasmodium infection characterized by blood-brain barrier breakdown. Here, we have identified that a receptor EphA2 is required for the breakdown of the blood-brain barrier during Plasmodium infection in mice. We found that expression of this receptor is critical for inducing brain inflammation, recruiting immune cells to the brain, and disruption brain endothelial cell junctions. Inhibiting activation of this receptor using two different treatment approaches also prevented blood-brain barrier breakdown in mice. Thus, along with identifying a new molecule critical for cerebral malaria in mice we also provide a basis for exploring this receptor as a novel therapeutic target in human cerebral malaria in the future.

Fatty acid‐binding protein 7 (FABP7), one of the fatty acid (FA) chaperones involved in the modulation of intracellular FA metabolism, is highly expressed in glioblastoma, and its expression is associated with decreased patients' prognosis. Previously, we demonstrated that FABP7 requires its binding partner to exert its function and that a mutation in the FA‐binding site of FABP7 affects tumour biology. Here, we explored the role of FA ligand binding for FABP7 function in tumour proliferation and examined the mechanism of FABP7 and ligand interaction in tumour biology. We discovered that among several FA treatment, oleic acid (OA) boosted cell proliferation of FABP7‐expressing cells. In turn, OA increased FABP7 nuclear localization, and the accumulation of FABP7–OA complex in the nucleus induced the formation of nuclear lipid droplet (nLD), as well as an increase in colocalization of nLD with promyelocytic leukaemia (PML) nuclear bodies. Furthermore, OA increased mRNA levels of proliferation‐related genes in FABP7‐expressing cells through histone acetylation. Interestingly, these OA‐boosted functions were abrogated in FABP7‐knockout cells and mutant FABP7‐overexpressing cells. Thus, our findings suggest that FABP7–OA intracellular interaction may modulate nLD formation and the epigenetic status thereby enhancing transcription of proliferation‐regulating genes, ultimately driving tumour cell proliferation.

BackgroundDespite intensive therapies, outcomes for high-risk pediatric brain tumors (PBTs) remain dismal, prompting the search for novel treatments. DNA methyltransferase inhibitors (DNMTi) have been shown to prime tumors to improve response to checkpoint inhibition. The aim of this study was to investigate the potential of decitabine (DAC), in combination with a PD-1 inhibitor, to improve survival in pediatric high-risk brain tumor models. Methods: Analysis of human PBT datasets was performed to determine gene expression levels of immune cell markers. Tumor response to DAC, with or without a PD-1 inhibitor, was tested in murine models representing H3-wildtype diffuse intrinsic pontine glioma (DIPG), H3K27-mutant diffuse midline glioma (DMG), atypical teratoid rhabdoid tumor (ATRT), and medulloblastoma (MB). CyTOF analysis of allograft tumors was performed to characterize changes within the tumor microenvironment. Results: Analysis of PBT subtypes revealed heterogeneous expression of immune cell markers, checkpoint receptors, and MHC molecules. DAC treatment decreased DNA methylation and increased neoantigen expression in human and mouse tumor cells. DAC treatment resulted in prolonged survival in syngeneic mouse models of DIPG and ATRT but not DMG and MB models. However, no added survival benefit was observed when combined with a PD-1 inhibitor. CyTOF analysis of mouse tumors revealed changes in local immune cell infiltration. Conclusions: DAC alone or in combination with a checkpoint inhibitor can alter the immune microenvironment in mouse tumor models. Changes were observed in H3-wildtype DIPG and ATRT models, suggesting that certain tumor subtypes may respond to immune priming with DNMTi.

Pediatric high-grade gliomas (pHGGs), including diffuse intrinsic pontine glioma (DIPG), are highly aggressive tumors with dismal prognoses despite multimodal therapy including surgery, radiation therapy, and chemotherapy. To achieve cellular immortality cancer cells must overcome replicative senescence and apoptosis by activating telomere maintenance mechanisms (TMMs) through the reactivation of telomerase activity or using alternative lengthening of telomere (ALT) pathways. Although the ALT phenotype is more prevalent in pHGGs compared to adult HGGs, the molecular pathway and the prognostic significance of ALT activation are not well understood in pHGGs. Here, we report the heterogeneity of TMM in pHGGs and their association with genetic alterations. Additionally, we show that sensitivity to the protein kinase ataxia telangiectasia- and RAD3-related protein (ATR) inhibitor and the ATR downstream target CHK1 is not specific to pHGG ALT-positive cells. Together, these findings underscore the need for novel therapeutic strategies to target ALT in pHGG tumors.