A Novel Mouse Model for Cerebral Venous Sinus Thrombosis

Brain alterations and neurologic disorder progression induced by lymphatic dysfunction in the head and neck region

The potential negative impact of lymphatic dysfunction caused by head and neck cancer treatment remains underexplored. Emerging evidence suggests that waste clearance and fluidic balance in the brain are connected to the peripheral lymphatic system in the head and neck region, implying that lymphatic injury in this area could contribute to brain damage. This study aimed to investigate the pathological alterations in the brain induced by peripheral lymphatic dysfunction in the head and neck region using the lymphatic obstruction animal model. An animal model underwent cervical lymph node dissection combined with radiation therapy to simulate the condition with the peripheral lymphatic dysfunction in the head and neck region after cancer treatment. Lymphatic drainage impairment in the head and neck region was associated with significant swelling, disrupted lymphatic drainage, and immune cell infiltration in the white matter. The imaging techniques revealed ventricular enlargement and increased brain water content caused by fluid imbalance leading to significant structural alterations in the brain. Histopathological analysis demonstrated structural brain alterations similar to that of hydrocephalus and cerebral edema, while rotarod tests showed a substantial decline in motor performance. These findings highlight the impact of peripheral lymphatic dysfunction on brain integrity and function. This study provides evidence that brain damage in head and neck cancer patients may be influenced not only by chemotherapy or radiotherapy but also by lymphatic dysfunction caused by surgical interventions. Lymphatic injury in the head and neck region emerges as a potential risk factor for brain damage, underscoring the need for further research into preventive and therapeutic strategies.

Exacerbation of thromboinflammation by JAK2V617F mutation worsens the prognosis of cerebral venous sinus thrombosis

ABSTRACT

Cerebral venous sinus thrombosis (CVST) is an uncommon venous thromboembolic event accounting for <1% of strokes resulting in brain parenchymal injuries. JAK2V617F mutation, the most frequent driving mutation of myeloproliferative neoplasms, has been reported to be associated with worse clinical outcomes in patients with CVST. We investigated whether hematopoietic JAK2V617F expression predisposes to specific pathophysiological processes and/or worse prognosis after CVST. Using an in vivo mouse model of CVST, we analyzed clinical, biological, and imaging outcomes in mice with hematopoietic-restricted Jak2V617F expression, compared with wild-type Jak2 mice. In parallel, we studied a human cohort of JAK2V617F-positive or -negative CVST. Early after CVST, mice with hematopoietic Jak2V617F expression had increased adhesion of platelets and neutrophils in cerebral veins located in the vicinity of CVST. On day 1, Jak2V617F mice had a worse outcome characterized by significantly more frequent and severe intracranial hemorrhages (ICHs) and higher mortality rates. Peripheral neutrophil activation was enhanced, as indicated by higher circulating platelet-neutrophil aggregates, upregulated CD11b expression, and higher myeloperoxydase plasma level. Concurrently, immunohistological and brain homogenate analysis showed higher neutrophil infiltration and increased blood-brain barrier disruption. Similarly, patients with JAK2V617F-positive CVST tended to present higher thrombotic burden and had significantly higher systemic immune-inflammation index, a systemic thromboinflammatory marker, than patients who were JAK2V617F-negative. In mice with CVST, our study corroborates that Jak2V617F mutation leads to a specific pattern including increased thrombotic burden, ICH, and mortality. The exacerbated thromboinflammatory response, observed both in mice and patients positive for JAK2V617F, could contribute to hemorrhagic complications.

Sequential transcriptomic alterations in the cerebral cortex of mice after cerebral venous sinus thrombosis

To investigate the expression alterations of specific genes that occur after venous stroke, we identified differentially expressed genes (DEGs) between sham and damaged cortical tissues at 2 and 7 days after induction of cerebral venous sinus thrombosis (CVST) model. The profiles of DEGs were analyzed using GO, KEGG, GSEA, and PPI, and the crucial gene was further verified by western blot and immunofluorescence. We found 969 and 883 DEGs at 2 and 7 days after CVST, respectively. A marked increase in biological-process categories, such as immune system process and inflammatory response, and a decrease in neuropeptide signaling pathway were observed both at 2 and 7 days post-CVST. The KEGG pathway was enriched to varying degrees on complement and coagulation cascades, cytokine-cytokine receptor interaction, and multiple immune-inflammatory signaling pathways at 2 and 7 days post-CVST, separately. Furthermore, GSEA highlights the potential roles of the NOD-like receptor signaling pathway and cytokine-cytokine receptor interaction in CVST. Importantly, numerous genes related to KEGG pathways above featured prominently in the PPI network analysis, with IL1b being one of the most conspicuous. These time-dependent alterations in gene profiles and enrichment pathways reveal the unique pathophysiological characteristics of CVST and indicate novel therapeutic targets for venous stroke. SIGNIFICANCE: Cerebral venous sinus thrombosis (CVST) is an underrated and potentially fatal cause of stroke with a reported mortality of 5-10% worldwide. Currently, in addition to anticoagulant and thrombolytic therapy, effective treatments targeting the injured brain parenchyma after CVST remain limited. Besides, accurate diagnostic markers are still sorely lacking. In the present study, we will detect the transcriptomic alterations of the cerebral cortex of mice post-CVST by RNA-sequencing, screen differentially expressed genes and abnormal pathways through bioinformatics methods, analyze the correlation of these signals and CVST pathology, and finally validate the key molecules through western blot and immunofluorescence assays. Collectively, the study aimed to offer a reference for the discovery of specific genes/pathway alterations in the damaged cortical tissues of CVST mice and further reveal the underlying pathogenesis, thereby providing evidence for the diagnosis and treatment of CVST.

Fabry-Perot Interferometric Fiber-Optic Sensor for Rapid and Accurate Thrombus Detection

We present a fiber-optic sensor based on the principles of a Fabry-Perot interferometer (FPI), which promptly, sensitively, and precisely detects blood clot formation. This sensor has two types of sensor tips; the first was crafted by splicing a tapered fiber into a single-mode fiber (SMF), where fine-tuning was achieved by adjusting the tapered diameter and length. The second type is an ultra-compact blood FPI situated on the core of a single-mode fiber. The sensor performance was evaluated via clot-formation-indicating spectrum shifts induced by the varied quantities of a thrombin reagent introduced into the blood. The most remarkable spectral sensitivity of the micro-tip fiber type was approximately 7 nm/μL, with a power sensitivity of 4.1 dB/μL, obtained with a taper fiber diameter and length of 55 and 300 μm, respectively. For the SMF type, spectral sensitivity was observed to be 8.7 nm/μL, with an optical power sensitivity of 0.4 dB/μL. This pioneering fiber-optic thrombosis sensor has the potential for in situ applications, healthcare, medical monitoring, harsh environments, and chemical and biological sensing. The study underscores the scope of optical technology in thrombus detection, establishing a platform for future medical research and application.

State of the art in cerebral venous sinus thrombosis animal models

Cerebral venous sinus thrombosis (CVST) is an uncommon venous thromboembolic event accounting for less than 1% of strokes resulting in brain parenchymal injuries. Diagnosis and prognosis are still challenging due to highly variable clinical course and etiologies. Beyond thrombosis, different CVST-related parenchymal injuries may occur and include edema, ischemic strokes, and intra-cerebral hemorrhage (ICH; i.e., parenchymal/subdural hematomas, and subarachnoid hemorrhages), which are identified in 40%-60% of patients without clearly identified mechanisms. In this perspective, experimental animal models contribute to the understanding of initiation, propagation, and resolution of thrombosis, as well as brain-related damages. Last but not least, animal models may be useful to study new therapeutic approaches. In this review, we provide a comprehensive overview of CVST experimental models, focusing on their strengths, limits, and contribution to the current knowledge.

A novel severe cerebral venous thrombosis rat model based on semi-ligation combined with ferric chloride and thrombin

AIMS

An applicable cerebral venous sinus thrombosis (CVST) model is imperative for exploring its pathophysiology. We established a novel severe CVST model using semi-ligation, ferric chloride, and thrombin.

METHODS

A total of 138 male Sprague-Dawley rats were randomly divided into semi-ligation (n = 75) and non-semi-ligation (n = 63) groups. A sham group (n = 46) was also included. We compared short-term and long-term neurological and cognitive dysfunction, mortality rates, thrombus load, venous infarction volume, the blood-brain barrier permeability, brain water content, and microglia activation among the three groups.

RESULTS

Thrombi involving multiple venous sinuses appeared in all semi-ligation rats within 2 days postoperatively. Compared with the non-semi-ligation group, short-term and long-term neurological dysfunction were more severe (p < 0.05), and thrombus weight, venous infarction volumes, and microglia activation were more significant (p < 0.05) in the semi-ligation group. Further, the cognitive function of the semi-ligation group significantly decreased (p < 0.05) on postoperative day 21. Cumulative mortality rates between the semi-ligation and non-semi-ligation groups did not differ significantly.

CONCLUSION

Semi-ligation combined with ferric chloride and thrombin can produce a severe CVST model with multiple venous sinus involvement, which is suitable for short- and long-term neurological and cognitive dysfunction assessment.

Activating cGAS-STING axis contributes to neuroinflammation in CVST mouse model and induces inflammasome activation and microglia pyroptosis

Background

Neuroinflammation-induced injury is intimately associated with poor prognosis in patients with cerebral venous sinus thrombosis (CVST). The cyclic GMP-AMP synthase–stimulator of interferon gene (cGAS–STING) axis is a cytoplasmic double-stranded DNA (dsDNA) sensing pathway has recently emerged as a crucial mediator of neuroinflammation in ischemic stroke. However, the role of the cGAS–STING pathway in modulating post-CVST inflammation and the underlying mechanisms involved remain unclear.

Methods

A CVST model was induced by ferric chloride in male C57BL/6J mice. The selective cGAS inhibitor RU.521, STING agonist 2′3′-cGAMP, and STING siRNA were delivered by intranasal administration or intraventricular injection. Post-CVST assessments included rotarod test, TUNEL staining, Fluoro-Jade C staining, dihydroethidium staining, western blotting, qPCR, immunofluorescence, immunohistochemistry, ELISA and flow cytometry.

Results

cGAS, STING, NLRP3 and GSDMD were significantly upregulated after CVST and mostly in the microglia of the mouse brain. CVST triggered the release of dsDNA into the cytoplasm and elicited an inflammatory response via activating the cGAS–STING axis. RU.521 decreased the levels of 2′3′-cGAMP, STING and downstream inflammatory cytokines, and suppressed the expressions of NLRP3 inflammasome and pyroptosis-pertinent components containing cleaved caspase-1, GSDMD, GSDMD-C, pro- and cleaved IL-1β, and cleaved IL-1β/pro-IL-1β. Besides, RU.521 treatment also reduced oxidative stress, lessened the numbers of microglia and neutrophils, and ameliorated neuronal apoptosis, degeneration along with neurological deficits post-CVST. 2′3'-cGAMP delivery enhanced the expressions of STING and related inflammatory mediators, NLRP3 inflammasome and pyroptosis-relevant proteins, whereas these alterations were significantly abrogated by the silencing of STING by siRNA.

Conclusions

Our data demonstrate that repression of the cGAS–STING pathway diminishes the neuroinflammatory burden of CVST and highlight this approach as a potential therapeutic tactic in CVST-mediated pathologies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02511-0.

A novel rat model for cerebral venous sinus thrombosis: verification of similarity to human disease via clinical analysis and experimental validation

Background

Cerebral venous sinus thrombosis (CVST) is a rare neurovascular disorder with highly variable manifestations and clinical courses. Animal models properly matched to the clinical form of CVST are necessary for elucidating the pathophysiology of the disease. In this study, we aimed to establish a rat model that accurately recapitulates the clinical features of CVST in human patients.

Methods

This study consisted of a clinical analysis and animal experiments. Clinical data for two centres obtained between January 2016 and May 2021 were collected and analysed retrospectively. In addition, a Sprague–Dawley rat model of CVST was established by inserting a water-swellable rubber device into the superior sagittal sinus, following which imaging, histological, haematological, and behavioural tests were used to investigate pathophysiological changes. Principal component analysis and hierarchical clustering heatmaps were used to evaluate the similarity between the animal models and human patients.

Results

The imaging results revealed the possibility of vasogenic oedema in animal models. Haematological analysis indicated an inflammatory and hypercoagulable state. These findings were mostly matched with the retrospective clinical data. Pathological and serological tests further revealed brain parenchymal damage related to CVST in animal models.

Conclusions

We successfully established a stable and reproducible rat model of CVST. The high similarity between clinical patients and animal models was verified via cluster analysis. This model may be useful for the study of CVST pathophysiology and potential therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03374-y.