Cellular and molecular mechanisms of radiation-induced brain injury: can peripheral markers be detected?

Endothelial marker profiles in cerebral radiation-induced vasculopathy: A comparative immunohistochemical analysis

Radiation therapy results in radiation-induced vasculopathy, characterized by alterations in the vascular architecture stemming from radiation exposure. The exact molecular pathways and associated pathologies of this condition have yet to be comprehensively understood. This study aimed to identify specific markers' roles in cerebral vascular endothelial injury pathogenesis after radiosurgery and explore their unique expression patterns in diverse pathologies post-stereotactic radiosurgery. A retrospective cohort study was conducted to assess the expression profiles of endothelial markers via immunohistochemical analysis in 25 adult patients (13 males and 12 females) who had undergone neurosurgical resection for various central nervous system pathologies following stereotactic radiosurgery or radiotherapy from 2001 to 2015. Our findings revealed strong immunohistochemical expression of ICAM-1 and E-selectin across various disease states, while MMP-9, PAI-1, and eNOS exhibited moderate expression levels. In contrast, VCAM-1 and P-Selectin had the weakest expression across all groups. Notably, while individual markers showed significant variations in expression levels when comparing different diseases (P < .001), no substantial differences were found in the overall immunohistochemical expression patterns across the 5 distinct pathologies studied (P = .407, via 2-way ANOVA). Despite the varied long-term effects of radiotherapy on the vascular endothelium, a common thread of inflammation runs through the pathology of these conditions. The distinct patterns of marker expression identified in our study suggest that different markers play unique roles in the development of radiation-induced vasculopathy. These findings offer insights that could lead to the development of novel preventive strategies and treatments.

Transcriptional expression of radiation-induced early cortical morphological alterations and its association with radiation necrosis in patients with nasopharyngeal carcinoma

PURPOSE

To explore the effects of standard radiotherapy on cortical morphology and its potential transcriptional expression, and to determine the predictive power of cortical morphological measurement at the early stage for radiation necrosis (RN) occurrence within 3 years post-radiotherapy in patients with nasopharyngeal carcinoma (NPC).

METHODS

185 NPC patients participated. Pre-treatment and post-radiotherapy (1-3 months) structural MRI were collected longitudinally and prospectively. Multiple cortical morphological indices were compared between pre-treatment and post-radiotherapy. Brain-wide gene expression was used to assess the transcriptional profiles associated with radiation-induced cortical morphological changes. Machine learning was used to construct predictive models for RN with cortical morphological alterations at the early stage.

RESULTS

Relative to pre-treatment, NPC patients exhibited a widespread reduction in cortical volume (CV) and cortical thickness (CT) post-radiotherapy (p < 0.001). Partial least squares regression analysis revealed that radiotherapy-related cortical atrophy was closely related to transcriptional profiles (p < 0.001), with the most correlated genes enriched in ATPase Na+/K+ transporting alpha-1 and alpha-3 polypeptide and respiratory electron transport chain. Furthermore, models constructed with cortical morphological features at 1-3 months post-radiotherapy had favorable predictive power for RN occurrence in NPC patients within 3-year follow-up, the area under the curve was 0.854 and 0.843 for CV and CT, respectively.

CONCLUSIONS

NPC patients exhibited widespread cortical atrophy at 1-3 months post-radiotherapy, which was closely correlated with dysfunction of the ATPase Na+/K+ transporting alpha-1 and alpha-3 polypeptide and respiratory electron transport chain. Cortical morphology at 1-3 months post-radiotherapy may serve as an early biomarker for identifying RN.

Amifostine-Loaded Nanocarrier Traverses the Blood-Brain Barrier and Prevents Radiation-Induced Brain Injury

Radiation-induced brain injury (RIBI) is a severe, irreversible, or even life-threatening cerebral complication of radiotherapy in patients with head and neck tumors, and there is no satisfying prevention and effective treatment available for these patients. Amifostine (AMF) is a well-known free radical scavenger with demonstrated effectiveness in preventing radiation-induced toxicity. However, the limited permeability of AMF across the blood-brain barrier (BBB) when administered intravenously reduces the effectiveness of AMF in preventing RIBI. Herein, we construct a nanoparticle (NP) platform for BBB delivery of AMF. AMF is conjugated with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-n-[poly(ethylene glycol)]-hydroxy succinamide [DSPE-PEG-NHS, PEG M 2000], and the product is DSPE-PEG-AMF. Then, the nanoparticles (DAPP NPs) were formed by self-assembly of poly(lactic-co-glycolic acid) (PLGA), DSPE-PEG-AMF, and polysorbate 80 (PS 80). PEG shields the nanoparticles from blood clearance by the reticuloendothelial system and lengthens the drug circulation time. PS 80 is used to encapsulate nanoparticles for medication delivery to the brain. The results of our study showed that DAPP NPs were able to effectively penetrate the blood-brain barrier (BBB) in healthy C57BL/6 mice. Furthermore, in a well-established mouse model of X-knife-induced brain injury, treatment with DAPP NPs (corresponding to 250 mg/kg AMF) was found to significantly reduce the volume of brain necrosis compared to mice treated with AMF (250 mg/kg). Importantly, the use of DAPP NPs was also shown to significantly mitigate the effects of radiation-induced neuronal damage and glial activation. This work presents a convenient brain-targeted AMF delivery system to achieve effective radioprotection for the brain, providing a promising strategy with tremendous clinical translation potential.

Biomarkers of Brain Damage Induced by Radiotherapy

Radiotherapy remains currently a critical component for both primary and metastatic brain tumors either alone or in combination with surgery, chemotherapy, and molecularly targeted agents, while it could cause simultaneously normal brain tissue injury leading to serious health consequences, that is, development of cognitive impairments following cranial radiotherapy is considered as a critical clinical disadvantage especially for the whole brain radiotherapy. Biomarkers can help to detect the accurate physiology or conditions of patients with brain tumor and develop effective treatment procedures for these patients. In the near future, biomarkers will become one of the prime driving forces of cancer treatment. In this minireview, we analyze the documented work on the acute brain damage and late consequences induced by radiotherapy, identify the biomarkers, in particular, the predictive biomarkers for the damage, and summarize the biological significance of the biomarkers. It is expected that translation of these research advance to radiotherapy would assist stratifying patients for optimized treatment and improving therapeutic efficacy and the quality of life.

[Multicystic transformation of the post-radiation necrosis zone of the brain. A case report and literature review]

Post-radiation cyst of the brain is a rare complication that often arises many years after irradiation for head and neck neoplasms. The majority of the articles devoted to this problem are small samples or case reports. Nevertheless, the overall number of these patients is steadily increasing. The feature of post-radiation cysts is gradual enlargement followed by general cerebral and focal symptoms and ineffectiveness of therapy. Some patients with clinically significant post-radiation cysts can require surgical treatment. Insertion of Ommaya reservoir may be preferred in these patients. In some cases, this method is ineffective and more complex surgeries may be required. The objectives of this report were to analyze literature data and describe the patient with multiple recurrent brain cysts after previous irradiation for frontotemporal skin melanoma. Twenty-seven publications were analyzed for the period from 1997 to 2018. According to the literature, the incidence of post-radiation cysts varies from 0.4% to 28%, timing of occurrence - from 2 months to 27 years. These values significantly depend on the underlying disease. We report a 27-year-old patient who admitted to the Burdenko Neurosurgery Center with focal and general cerebral symptoms after irradiation for skin melanoma of the right frontotemporal region. These symptoms were caused by cystic lesion of the right temporal and frontal lobes. Surgical treatment consisted in insertion of 2 Ommaya reservoirs. This approach ensured complete regression of the cyst in the right temporal lobe and mild decrease of the cyst in the right frontal lobe.