Immunosuppressive Microenvironment in H3K27 Mutant Pediatric Diffuse Midline Glioma: Single-Cell and Bioinformatics Insights on CD8A, IL7R, and ICAM1.

BACKGROUND: Diffuse midline gliomas (DMG) pose a grave threat as a malignant tumor primarily affecting children in the pons region. These tumors exhibit a distinct and heightened resistance to therapeutic interventions, coupled with exceptionally aggressive behavior. METHODS: In this study, we accessed DMG data from the Gene Expression Omnibus (GEO) database. Subsequently, we performed functional annotation and conducted pathway enrichment analysis as well as gene set enrichment analysis (GSEA). Constructing a protein-protein interaction (PPI) network, we identified pivotal hub genes. To evaluate the impact of these hub genes on immune infiltration, we employed the CIBERSORT algorithm. Furthermore, to bolster our findings, we conducted a single-cell analysis. RESULTS: Our findings indicate the involvement of CD8A, IL7R, and ICAM1 in immune responses targeting diverse immune cell types, such as T cells, neutrophils, NK cells, dendritic cells, γδ T cells, and Macrophages M1. Additionally, the presence of immune checkpoints, including IDO1 and TIGIT, likely contributes to intratumoral immunosuppression, thereby fostering the development of an aggressive phenotype and resistance in pediatric DMG. CONCLUSION: In conclusion, the collective findings of our study suggest the potential role of CD8A, IL7R, and ICAM1 as innovative biomarkers for diagnosing and prognosticating pediatric DMG. Moreover, these molecules hold promise as therapeutic targets in the management of this disease. The implications of our research underscore the importance of exploring these novel avenues for improved patient outcomes.

Ketamine exerts dual effects on the apoptosis of primary cultured hippocampal neurons from fetal rats in vitro.

Ketamine, a noncompetitive N-methyl D-aspartate (NMDA) receptor antagonist, is widely used in pediatric clinical practice. The neuroprotective and neurotoxic effects of ketamine on brain neurons during development remain controversial. The reason may be related to the different concentrations of ketamine used in practice and the small range of concentrations used in previous studies. In this study, cultured hippocampal neurons were treated with ketamine in a wide range of concentrations to comprehensively observe the effects of different concentrations of ketamine on neurons. We demonstrated that low concentrations of ketamine (10 µM, 100 µM and 1000 µM) promoted neuronal survival (p < 0.05) and reduced neuronal apoptosis (p < 0.05) compared with those of the control group. High concentrations of ketamine (2000 µM, 2500 µM and 3000 µM) reduced neuronal survival (p < 0.05) and promoted neuronal apoptosis (p < 0.05). The p38 MAPK inhibitor SB203580 reduced neuronal apoptosis induced by high concentrations of ketamine (2500 µM) (p < 0.05). Our findings indicate that ketamine exerts a dual effect on the apoptosis of primary cultured fetal rat hippocampal neurons in vitro and that the neurotoxic effects of ketamine are related to activation of the p38 MAPK signaling pathway.

scRNA-seq and proteomics reveal the distinction of M2-like macrophages between primary and recurrent malignant glioma and its critical role in the recurrence.

AIMS: Tumor-associated macrophages (TAMs) in the immune microenvironment play an important role in the increased drug resistance and recurrence of malignant glioma, but the mechanism remains incompletely inventoried. The focus of this study was to investigate the distinctions of M2-like TAMs in the immune microenvironment between primary and recurrent malignant glioma and its influence in the recurrence. METHODS: We employed single-cell RNA sequencing to construct a single-cell atlas for a total of 23,010 individual cells from 6 patients with primary or recurrent malignant glioma and identified 5 cell types, including TAMs and malignant cells. Immunohistochemical techniques and proteomics analysis were performed to investigate the role of intercellular interaction between malignant cells and TAMs in the recurrence of malignant glioma. RESULTS: Six subgroups of TAMs were annotated and M2-like TAMs were found to increase in recurrent malignant glioma significantly. A pseudotime trajectory and a dynamic gene expression profiling during the recurrence of malignant glioma were reconstructed. Up-regulation of several cancer pathways and intercellular interaction-related genes are associated with the recurrence of malignant glioma. Moreover, the M2-like TAMs can activate the PI3K/Akt/HIF-1α/CA9 pathway in the malignant glioma cells via SPP1-CD44-mediated intercellular interaction. Interestingly, high expression of CA9 can trigger the immunosuppressive response in the malignant glioma, thus promoting the degree of malignancy and drug resistance. CONCLUSION: Our study uncovers the distinction of M2-like TAMs between primary and recurrent glioma, which offers unparalleled insights into the immune microenvironment of primary and recurrent malignant glioma.