Search Results (5)

Background: Malignant gliomas, and notably glioblastoma, are highly aggressive brain tumors. Understanding the mechanisms underlying their progression is crucial for developing more effective treatments. Recent studies have highlighted the role of microglia and brain macrophages in glioblastoma development, but the specific interactions between these immune cells and glioblastoma stem cells (GSCs) remain unclear. Methods: To address this question, we have utilized AI-assisted cell recognition to investigate the spatial relationship between GSCs expressing high levels of CD276 (B7-H3) and microglia- and bone marrow-derived brain macrophages, respectively. Results: Using PathoFusion, our previously developed open-source AI framework, we were able to map specific immunohistochemical phenotypes at the single-cell level within whole-slide images. This approach enabled us to selectively identify Iba1+ and CD163+ macrophages as well as CD276+ GSCs with high specificity and to study their co-localization. Our analysis suggests a closer association of Iba1+ macrophages with GSCs than between CD163+ macrophages and GSCs in glioblastoma. Conclusions: Our findings provide novel insights into the spatial context of tumor immunity in glioblastoma and point to microglia-GSC interactions as a potential mechanism for tumor progression, especially during diffuse tissue infiltration. These findings have significant implications for our understanding of glioblastoma biology, providing a foundation for a comprehensive analysis of microglia activation phenotypes during glioma development. This, in turn, may lead to new therapeutic strategies targeting the early stages of the immune microenvironment of glioblastoma. Full article

The viral gene delivery of optogenetic actuators to the surviving inner retina has been proposed as a strategy for restoring vision in advanced retinal degeneration. We investigated the safety of ectopic expression of human rod opsin (hRHO), and two channelrhodopsins (enhanced sensitivity CoChR-3M and red-shifted ReaChR) by viral gene delivery in ON bipolar cells of the mouse retina. Adult Grm6^Cre mice were bred to be retinally degenerate or non-retinally degenerate (homozygous and heterozygous for the rd1^Pde6b mutation, respectively) and intravitreally injected with recombinant adeno-associated virus AAV2/2(quad Y-F) serotype containing a double-floxed inverted transgene comprising one of the opsins of interest under a CMV promoter. None of the opsins investigated caused changes in retinal thickness; induced apoptosis in the retina or in transgene expressing cells; or reduced expression of PKCα (a specific bipolar cell marker). No increase in retinal inflammation at the level of gene expression (IBA1/AIF1) was found within the treated mice compared to controls. The expression of hRHO, CoChR or ReaChR under a strong constitutive promoter in retinal ON bipolar cells following intravitreal delivery via AAV2 does not cause either gross changes in retinal health, or have a measurable impact on the survival of targeted cells. Full article

Allograft inflammatory factor-1 (AIF-1) is a calcium-binding scaffold/adaptor protein often associated with inflammatory diseases. Originally cloned from active macrophages in humans and rats, this gene has also been identified in other vertebrates and in several invertebrate species. Among metazoans, AIF-1 protein sequences remain relatively highly conserved. Generally, the highest expression levels of AIF-1 are observed in immunocytes, suggesting that it plays a key role in immunity. In mammals, the expression of AIF-1 has been reported in different cell types such as activated macrophages, microglial cells, and dendritic cells. Its main immunomodulatory role during the inflammatory response has been highlighted. Among invertebrates, AIF-1 is involved in innate immunity, being in many cases upregulated in response to biotic and physical challenges. AIF-1 transcripts result ubiquitously expressed in all examined tissues from invertebrates, suggesting its participation in a variety of biological processes, but its role remains largely unknown. This review aims to present current knowledge on the role and modulation of AIF-1 and to highlight its function along the evolutionary scale. Full article

Molecular imaging is essential for diagnosis and treatment planning for glioblastoma patients. Positron emission tomography (PET) with tracers for the detection of the solute carrier family 7 member 5 (SLC7A5; also known as the amino acid transporter light chain L system, LAT1) and for the mitochondrial translocator protein (TSPO) is successfully used to provide additional information on tumor volume and prognosis. The current approaches for TSPO-PET and the visualization of tracer ([18F] Fluoroethyltyrosine, FET) uptake by LAT1 (FET-PET) do not yet exploit the full diagnostic potential of these molecular imaging techniques. Therefore, we investigated the expression of TSPO and LAT1 in patient glioblastoma (GBM) samples, as well as in various GBM mouse models representing patient GBMs of different genetic subtypes. By immunohistochemistry, we found that TSPO and LAT1 are upregulated in human GBM samples compared to normal brain tissue. Next, we orthotopically implanted patient-derived GBM cells, as well as genetically engineered murine GBM cells, representing different genetic subtypes of the disease. To determine TSPO and LAT1 expression, we performed immunofluorescence staining. We found that both TSPO and LAT1 expression was increased in tumor regions of the implanted human or murine GBM cells when compared to the neighboring mouse brain tissue. While LAT1 was largely restricted to tumor cells, we found that TSPO was also expressed by microglia, tumor-associated macrophages, endothelial cells, and pericytes. The Cancer Genome Atlas (TCGA)-data analysis corroborates the upregulation of TSPO in a bigger cohort of GBM patient samples compared to tumor-free brain tissue. In addition, AIF1 (the gene encoding for the myeloid cell marker Iba1) was also upregulated in GBM compared to the control. Interestingly, TSPO, as well as AIF1, showed significantly different expression levels depending on the GBM genetic subtype, with the highest expression being exhibited in the mesenchymal subtype. High TSPO and AIF1 expression also correlated with a significant decrease in patient survival compared to low expression. In line with this finding, the expression levels for TSPO and AIF1 were also significantly higher in (isocitrate-dehydrogenase wild-type) IDH^WT compared to IDH mutant (IDH^MUT) GBM. LAT1 expression, on the other hand, was not different among the individual GBM subtypes. Therefore, we could conclude that FET- and TSPO-PET confer different information on pathological features based on different genetic GBM subtypes and may thus help in planning individualized strategies for brain tumor therapy in the future. A combination of TSPO-PET and FET-PET could be a promising way to visualize tumor-associated myeloid cells and select patients for treatment strategies targeting the myeloid compartment. Full article

In order to obtain unbiased results of target gene expression, selection of the most appropriate reference gene (RG) remains a key precondition. However, an experimental study focused on the validation of stably expressed RGs in the rat spinal cord (SC) during development or after spinal cord injury (SCI) is missing. In our study, we tested the stability of the expression of nine selected RGs in rat SC tissue during normal development (postnatal days 1–43, adulthood) and after minimal (mSCI) and contusion (cSCI) spinal cord injury. The following RGs were tested: common housekeeping genes of basal cell metabolism (Gapdh, Hprt1, Mapk6) and protein translation (Rpl29, Eef1a1, Eif2b2), as well as newly designed RGs (Gpatch1, Gorasp1, Cds2) selected according to the RefGenes tool of GeneVestigator. The stability of RGs was assessed by geNorm, NormFinder, and BestKeeper. All three applets favored Gapdh and Eef1a1 as the most stable genes in SC during development. In both models of SCI, Eif2b2 displayed the highest stability of expression, followed by Gapdh and Gorasp1/Hprt1 in cSCI, and Gapdh and Eef1a1 in the mSCI experiments. To verify our results, selected RGs were employed for normalization of the expression of genes with a clear biological context in the SC—Gfap and Slc1a3/Glast during postnatal development and Aif1/Iba1 and Cd68/Ed1 after SCI. Full article