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Vascular guidance is critical in developmental vasculogenesis and pathological angiogenesis. Brain tumors are strongly vascularized, and antiangiogenic therapy was anticipated to exhibit a strong anti-tumor effect in this tumor type. However, vascular endothelial growth factor A (VEGFA) specific inhibition had no significant impact in clinical practice of gliomas. More research is needed to understand the failure of this therapeutic approach. EphrinB2 has been found to directly interact with vascular endothelial growth factor receptor 2 (VEGFR2) and regulate its activity. Here we analyzed the expression of ephrinB2 and EphB4 in human glioma, we observed vascular localization of ephrinB2 in physiology and pathology and found a significant survival reduction in patients with elevated ephrinB2 tumor expression. Induced endothelial specific depletion of ephrinB2 in the adult mouse (efnb2i∆EC) had no effect on the quiescent vascular system of the brain. However, we found glioma growth and perfusion altered in efnb2i∆EC animals similar to the effects observed with antiangiogenic therapy. No additional anti-tumor effect was observed in efnb2i∆EC animals treated with antiangiogenic therapy. Our data indicate that ephrinB2 and VEGFR2 converge on the same pathway and intervention with either molecule results in a reduction in angiogenesis.
EphrinB2–EphB4 signaling is critical during embryogenesis for cardiovascular formation and neuronal guidance. Intriguingly, critical expression patterns have been discovered in cancer pathologies over the last two decades. Multiple connections to tumor migration, growth, angiogenesis, apoptosis, and metastasis have been identified in vitro and in vivo. However, the molecular signaling pathways are manifold and signaling of the EphB4 receptor or the ephrinB2 ligand is cancer type specific. Here we explore the impact of these signaling pathways in neurooncological disease, including glioma, brain metastasis, and spinal bone metastasis. We identify potential downstream pathways that mediate cancer suppression or progression and seek to understand it´s role in antiangiogenic therapy resistance in glioma. Despite the Janus-faced functions of ephrinB2–EphB4 signaling in cancer Eph signaling remains a promising clinical target.
Despite intensive research, glioblastoma remains almost invariably fatal. Various promising drugs targeting specific aspects of glioma biology, in addition to or as an alternative to antiproliferative chemotherapy, were not successful in larger clinical trials. Further insights into the biology of glioma and the mechanisms behind the evasive-adaptive response to targeted therapies is needed to help identify new therapeutic targets, prognostics, or predictive biomarkers. As a modulator of the canonically oncogenic Rho-GTPase pathway, Lipid phosphate phosphatase-related protein type 5 (LPPR5) is pivotal in influencing growth, angiogenesis, and therapeutic resistance. We used a GL261 murine orthotopic allograft glioma model to quantify the tumor growth and to obtain tissue for histological and molecular analysis. Epicortical intravital epi-illumination fluorescence video microscopy of the tumor cell spheroids was used to characterize the neovascular architecture and hemodynamics. GL261-glioma growth was delayed and decelerated after LPPR5 overexpression (LPPR5OE). We observed increased tumor cell apoptosis and decreased expression and secretion of vascular endothelial growth factor A in LPPR5OE glioma. Hence, an altered micro-angioarchitecture consisting of dysfunctional small blood vessels was discovered in the LPPR5OE tumors. Sunitinib therapy eliminated these vessels but had no effect on tumor growth or apoptosis. In general, LPPR5 overexpression generated a more benign, proapoptotic glioma phenotype with delayed growth and a dysfunctional vascular architecture.
Tumor–endothelial cell interactions represent an essential mechanism in spinal metastasis. Ephrin-B2–EphB4 communication induces tumor cell repulsion from the endothelium in metastatic melanoma, reducing spinal bone metastasis formation. To shed further light on the Ephrin-B2–EphB4 signaling mechanism, we researched the effects of pharmacological EphB4 receptor stimulation and inhibition in a ligand-dependent/independent context. We chose a preventative and a post-diagnostic therapeutic window. EphB4 stimulation during tumor cell seeding led to an increase in spinal metastatic loci and number of disseminated melanoma cells, as well as earlier locomotion deficits in the presence of endothelial Ephrin-B2. In the absence of endothelial Ephrin-B2, reduction of metastatic loci with a later manifestation of locomotion deficits occurred. Thus, EphB4 receptor stimulation affects metastatic dissemination depending on the presence/absence of endothelial Ephrin-B2. After the manifestation of solid metastasis, EphB4 kinase inhibition resulted in significantly earlier manifestation of locomotion deficits in the presence of the ligand. No post-diagnostic treatment effect was found in the absence of endothelial Ephrin-B2. For solid metastasis treatment, EphB4 kinase inhibition induced prometastatic effects in the presence of endothelial Ephrin-B2. In the absence of endothelial Ephrin-B2, both therapies showed no effect on the growth of solid metastasis.
Introduction: Deep brain stimulation (DBS) has become a well-established treatment modality for a variety of conditions over the last decades. Multiple surgeries are an essential part in the postoperative course of DBS patients if nonrechargeable implanted pulse generators (IPGs) are applied. So far, the rate of subclinical infections in this field is unknown. In this prospective cohort study, we used sonication to evaluate possible microbial colonization of IPGs from replacement surgery. Methods: All consecutive patients undergoing IPG replacement between May 1, 2019 and November 15, 2020 were evaluated. The removed hardware was investigated using sonication to detect biofilm-associated bacteria. Demographic and clinical data were analyzed. Results: A total of 71 patients with a mean (±SD) of 64.5 ± 15.3 years were evaluated. In 23 of these (i.e., 32.4%) patients, a positive sonication culture was found. In total, 25 microorganisms were detected. The most common isolated microorganisms were Cutibacterium acnes (formerly known as Propionibacterium acnes) (68%) and coagulase-negative Staphylococci (28%). Within the follow-up period (5.2 ± 4.3 months), none of the patients developed a clinical manifest infection. Discussions/Conclusions: Bacterial colonization of IPGs without clinical signs of infection is common but does not lead to manifest infection. Further larger studies are warranted to clarify the impact of low-virulent pathogens in clinically asymptomatic patients.
Introduction: Deep brain stimulation (DBS) has become a well-established treatment modality for a variety of conditions over the last decades. Multiple surgeries are an essential part in the postoperative course of DBS patients if nonrechargeable implanted pulse generators (IPGs) are applied. So far, the rate of subclinical infections in this field is unknown. In this prospective cohort study, we used sonication to evaluate possible microbial colonization of IPGs from replacement surgery. Methods: All consecutive patients undergoing IPG replacement between May 1, 2019 and November 15, 2020 were evaluated. The removed hardware was investigated using sonication to detect biofilm-associated bacteria. Demographic and clinical data were analyzed. Results: A total of 71 patients with a mean (±SD) of 64.5 ± 15.3 years were evaluated. In 23 of these (i.e., 32.4%) patients, a positive sonication culture was found. In total, 25 microorganisms were detected. The most common isolated microorganisms were Cutibacterium acnes (formerly known as Propionibacterium acnes) (68%) and coagulase-negative Staphylococci (28%). Within the follow-up period (5.2 ± 4.3 months), none of the patients developed a clinical manifest infection. Discussions/Conclusions: Bacterial colonization of IPGs without clinical signs of infection is common but does not lead to manifest infection. Further larger studies are warranted to clarify the impact of low-virulent pathogens in clinically asymptomatic patients.
Background: Disease progression and delayed neurological complications are common after aneurysmal subarachnoid hemorrhage (aSAH). We explored the potential of quantitative blood-brain barrier (BBB) imaging to predict disease progression and neurological outcome.
Methods: Data were collected as part of the Co-Operative Studies of Brain Injury Depolarizations (COSBID). We analyzed retrospectively, blinded and semi-automatically magnetic resonance images from 124 aSAH patients scanned at 4 time points (24–48 h, 6–8 days, 12–15 days and 6–12 months) after the initial hemorrhage. Volume of brain with apparent pathology and/or BBB dysfunction (BBBD), subarachnoid space and lateral ventricles were measured. Neurological status on admission was assessed using the World Federation of Neurosurgical Societies and Rosen-Macdonald scores. Outcome at ≥6 months was assessed using the extended Glasgow outcome scale and disease course (progressive or non-progressive based on imaging-detected loss of normal brain tissue in consecutive scans). Logistic regression was used to define biomarkers that best predict outcomes. Receiver operating characteristic analysis was performed to assess accuracy of outcome prediction models.
Findings: In the present cohort, 63% of patients had progressive and 37% non-progressive disease course. Progressive course was associated with worse outcome at ≥6 months (sensitivity of 98% and specificity of 97%). Brain volume with BBBD was significantly larger in patients with progressive course already 24–48 h after admission (2.23 (1.23–3.17) folds, median with 95%CI), and persisted at all time points. The highest probability of a BBB-disrupted voxel to become pathological was found at a distance of ≤1 cm from the brain with apparent pathology (0·284 (0·122–0·594), p < 0·001, median with 95%CI). A multivariate logistic regression model revealed power for BBBD in combination with RMS at 24-48 h in predicting outcome (ROC area under the curve = 0·829, p < 0·001).
Interpretation: We suggest that early identification of BBBD may serve as a key predictive biomarker for neurological outcome in aSAH.
Fund: Dr. Dreier was supported by grants from the Deutsche Forschungsgemeinschaft (DFG) (DFG DR 323/5-1 and DFG DR 323/10–1), the Bundesministerium für Bildung und Forschung (BMBF) Center for Stroke Research Berlin 01 EO 0801 and FP7 no 602150 CENTER-TBI.
Dr. Friedman was supported by grants from Israel Science Foundation and Canada Institute for Health Research (CIHR). Dr. Friedman was supported by grants from European Union's Seventh Framework Program (FP7/2007–2013; grant #602102).