Tocilizumab Reduces Vasospasms, Neuronal Cell Death, and Microclot Formation in a Rabbit Model of Subarachnoid Hemorrhage

The mechanism of Zhenzhu Pills treating intracerebral hemorrhage secondary injury based on network pharmacology and molecular docking

BACKGROUND

Intracerebral hemorrhage (ICH) secondary injury is serious and affects patient's prognosis. The Zhenzhu Pills used to treat subacute ICH in Tibet has shown to have a certain curative effect. Network pharmacology and molecular docking technology are employed to explore the potential mechanism of Zhenzhu Pills. The components and potential targets of Zhenzhu Pills were screened from the Traditional Chinese Medicine Systems Pharmacology database. The Gene Expression Omnibus Series 24265 was used to screen differentially expressed genes between perihematomal tissue and normal brain.

METHODS

The herbs-components-targets network was established, with weighted eigenvalue to identify the core components and targets of Zhenzhu Pills treatment of ICH secondary injury. Targets' bioinformatics enrichment was proceeded by gene ontology and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis. Finally, molecular docking was used to identify the hydrogen bonding activity between the key components and action targets.

RESULTS

Five herbal drugs were screened from Traditional Chinese Medicine Systems Pharmacology database, with a total of 48 components and 234 targets. The Gene Expression Omnibus Series 24265 dataset was evaluated and 920 differentially expressed genes were identified. A total of 29 intersection targets of Zhenzhu Pills were explored in the treatment of ICH secondary injury. Drugs-components-targets network analysis showed that the pivotal targets were prostaglandin G/H synthase 2, interleukin 6, heme oxygenase-1, vascular endothelial growth factor, and vascular cell adhesion molecule 1, and the core components were quercetin, luteolin, and kaempferol. Gene ontology and KEGG pathway enrichment analysis showed that biological processes such as cell chemotaxis, wound healing, leukocyte migration, and regulation of body fluid levels played an important role in the secondary injury of ICH. The results of KEGG pathway analysis were mainly related to advanced glycation end products-receptor for advanced glycation end products signal pathway and tumor necrosis factor signal pathway. Molecular docking of 3 flavonoids with 5 core targets with the results also showed active hydrogen bonding.

CONCLUSIONS

This study provides insights into the potential mechanisms of Zhenzhu Pills in the treatment of secondary injuries resulting from ICH and highlights specific components, targets, and molecular pathways involved in this therapeutic effect. These possible therapeutic mechanisms include inhibiting inflammation, edema, oxidative stress, and so on.

Post-COVID-19 depression and serum interleukin 6 levels: A systematic review and meta-analysis of COVID-19 convalescents with and without depression

OBJECTIVES

Depression is among the psychiatric sequelae of COVID-19, affecting more than 20% of the convalescents. Its underlying pathophysiology remains unclear. Interleukin 6 (IL-6), a pro-inflammatory cytokine, plays a critical role in the COVID-19-associated cytokine storm, has been implicated in depressive disorders, and may thus be involved in post-COVID-19 depression.

METHODS

PubMed, Scopus, Embase, and Web of Science were systematically searched for relevant studies assessing peripheral IL-6 levels in convalescents who developed depression after COVID-19 vs. convalescents who did not.

RESULTS

Five studies were included in our systematic review, and four entered the meta-analysis. The meta-analysis revealed that post-COVID people with de novo depression did not have statistically significant differences in IL-6 levels compared to those without depression (standardised mean difference (SMD) = 0.09, 95% confidence interval (CI) = -0.35, 0.54, p-value = 0.68).

CONCLUSIONS

Although convalescents with depression did not have significantly higher IL-6 levels than convalescents without depression, the results should be interpreted considering the limited sample size and the low power of the included studies.

Cerebral Aneurysm and Interleukin-6: a Key Player in Aneurysm Generation and Rupture or Just One of the Multiple Factors?

Intracranial aneurysm (IA) rupture is a common cause of subarachnoid hemorrhage (SAH) with high mortality and morbidity. Inflammatory interleukins (IL), such as IL-6, play an important role in the occurrence and rupture of IA causing SAH. With this review we aim to elucidate the specific role of IL-6 in aneurysm formation and rupture in preclinical and clinical studies. IL-6 is a novel cytokine in that it has pro-inflammatory and anti-inflammatory signaling pathways. In preclinical and clinical studies of IA formation, elevated and reduced levels of IL-6 are reported. Poor post-rupture prognosis and increased rupture risk, however, are associated with higher levels of IL-6. By better understanding the relationships between IL-6 and IA formation and rupture, IL-6 may serve as a biomarker in high-risk populations. Furthermore, by better understanding the IL-6 signaling mechanisms in IA formation and rupture, IL-6 may optimize surveillance and treatment strategies. This review examines the association between IL-6 and IA, while also suggesting future research directions.

Systemic Inflammation after Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is one of the most severe neurological disorders, with a high mortality rate and severe disabling functional sequelae. Systemic inflammation following hemorrhagic stroke may play an important role in mediating intracranial and extracranial tissue damage. Previous studies showed that various systemic inflammatory biomarkers might be useful in predicting clinical outcomes. Anti-inflammatory treatment might be a promising therapeutic approach for improving the prognosis of patients with aSAH. This review summarizes the complicated interactions between the nervous system and the immune system.

THE NEUROPROTECTIVE EFFECT OF TOCILIZUMAB IN BRAIN ISCHEMIA REPERFUSION INJURY

OBJECTIVE

The aim: This research was conducted to assess the possible neuroprotective effect of Tocilizumab in brain ischemic reperfusion injury in rats.

PATIENTS AND METHODS

Materials and methods: 24 adult Sprague-Dawley rats were divided into four groups randomly. The sham group was given anesthesia at the same time as the other groups and was in the same condition as the other groups. Control group: 1 h of ischemia followed by 4 h of reperfusion. The vehicle group was the same as the control, but they were given the vehicle intraperitoneally (1 ml/kg of 0.9 % NaCl) for 7 days before the ischemia. The treatment group as the control group, but they were given tocilizumab (8 mg/ kg) intraperitoneally for 7 days before ischemia.

RESULTS

Results: control group, inducing ischemia/reperfusion increased infarction size considerably (p<0.001), when comparison to the control and vehicle groups, tocilizumab at dose (8 mg/kg) showed a significantly (p<0.001) smaller infraction area.

CONCLUSION

Conclusions: In a cerebral ischemia/reperfusion, a reduction in infarction area in injected with Tocilizumab medication was considered neuroprotective for cerebral ischemia/reperfusion.

Tocilizumab promotes repair of spinal cord injury by facilitating the restoration of tight junctions between vascular endothelial cells

BACKGROUND

Our previous study demonstrated that M1 macrophages could impair tight junctions (TJs) between vascular endothelial cells by secreting interleukin-6 (IL-6) after spinal cord injury (SCI). Tocilizumab, as a humanized IL-6 receptor (IL-6R) monoclonal antibody approved for the clinic, has been applied in the treatment of neurological diseases in recent years, but the treatment effect of Tocilizumab on the TJs restoration of the blood-spinal cord barrier (BSCB) after SCI remains unclear. This study aimed to explore the effect of Tocilizumab on the restoration of TJs between vascular endothelial cells and axon regeneration after SCI.

METHODS

In this study, the mouse complete spinal cord crush injury model was used, and Tocilizumab was continuously injected intrathecally until the day of sample collection. A PBS injection in the same location was included as a control. At 14 days postinjury (dpi) and 28 dpi, spinal cord tissue sections were examined via tissue immunofluorescence. The Basso Mouse Scale (BMS) scores and footprint analysis were used to verify the effect of Tocilizumab on the recovery of motor function in mice after SCI.

RESULTS

We demonstrated that depletion of macrophages has no effect on axon regeneration and motor functional recovery after SCI, but mice subjected to Tocilizumab showed a significant increase in axon regeneration and a better recovery in motor function during the chronic phase after SCI. Moreover, our study demonstrated that at 14 and 28 dpi, the expression of claudin-5 (CLDN5) and zonula occludens-1 (ZO-1) between vascular endothelial cells was significantly increased and the leakage of BSCB was significantly reduced in the injured core after daily intrathecal injection of Tocilizumab. Notably, the infiltration of CD68⁺ macrophages/microglia and the formation of fibrotic scar were decreased in the injured core after Tocilizumab treatment. Tocilizumab treatment could effectively reduce the IL-6 expression in macrophages in the injured core.

CONCLUSION

The application of Tocilizumab to antagonize IL-6R can effectively reduce the expression of IL-6 in macrophages and facilitate TJs restoration of the BSCB, which is beneficial for axon regeneration and motor functional recovery after SCI. Hence, Tocilizumab treatment is a potential therapeutic strategy for SCI.

Contemplating IL-6, a double-edged sword cytokine: Which side to use for stroke pathology?

Interleukin (IL)-6 is a unique cytokine due to its dual signaling, with one pathway being pro-inflammatory (trans) and the other homeostatic (classical). Both of these pathways have been implicated in neuroinflammation following stroke, with initial inflammatory mechanisms being protective and later anti-inflammatory signaling promoting ischemic tissue recovery. IL-6 plays a major role in stroke pathology. However, given these distinctive IL-6 signaling consequences, IL-6 is a difficult cytokine to target for stroke therapies. Recent research suggests that the ratio between the pro-inflammatory binary IL6:sIL6R complex and the inactive ternary IL6:sIL6R:sgp130 complex may be a novel way to measure IL-6 signaling at different time points following ischemic injury. This ratio may approximate functional consequences on individualized stroke therapies, allowing clinicians to determine whether IL-6 agonists or antagonists should be used at specific time points.

Probing Interleukin-6 in Stroke Pathology and Neural Stem Cell Transplantation

Stem cell transplantation is historically understood as a powerful preclinical therapeutic following stroke models. Current clinical strategies including clot busting/retrieval are limited by their time windows (tissue plasminogen activator: 3-4 h) and inevitable reperfusion injuries. However, 24+ h post-stroke, stem cells reduce infarction size, improve neurobehavioral performance, and reduce inflammatory agents including interleukins. Typically, interleukin-6 (IL-6) is regarded as proinflammatory, and thus, preclinical studies often discuss it as beneficial for neurological recuperation when stem cells reduce IL-6's expression. However, some studies have also demonstrated neurological benefit with upregulation of IL-6 or preconditioning of stem cells with IL-6. This review specifically focuses on stem cells and IL-6, and their occasionally disparate, occasionally synergistic roles in the setting of ischemic cerebrovascular insults.

6-Gingerol attenuates subarachnoid hemorrhage-induced early brain injury via GBP2/PI3K/AKT pathway in the rat model

Numerous studies have elucidated the neuroprotective effect of 6-gingerol in central nervous system diseases. However, the potential role and mechanism of 6-gingerol on early brain injury (EBI) after subarachnoid hemorrhage (SAH) remains poorly understood. Here, we report that 6-gingerol exerts a neuroprotective effect on SAH-induced EBI through the GBP2/PI3K/AKT pathway. A SAH rat model was established by injecting femoral artery blood into the cisterna magna. 6-gingerol or vehicle was injected intraperitoneally 1 hour post-SAH induction. We found that the neurological function score and brain edema of SAH rats were significantly improved after 6-gingerol treatment, as well as neuronal apoptosis was attenuated in SAH rats by Nissl staining assay and TUNEL assay. To further explore potential molecular mechanisms associated with 6-gingerol, RNA sequencing was implemented to investigate the differences in transcriptomes between SAH rats with and without 6-gingerol treatment; and found that the expression of guanylate-binding protein 2 (GBP2) evidently was suppressed with 6-gingerol treatment compared to vehicle group. In addition, dual immunofluorescence was also employed to investigate changes in neurons, astrocytes, and microglia after 6-gingerol treatment. The results showed that GBP2 was expressed in neurons but not astrocytes or microglia. Western blotting analysis results demonstrated that the PI3K/AKT pathway was activated in the SAH rats treated with 6-gingerol. Furthermore, recombinant GBP2 protein and LY294002 (PI3K inhibitor) treatment reversed the effects of 6-gingerol treatment in SAH rats. These results indicate that 6-gingerol suppressed the expression of GBP2 to activate the PI3K/AKT pathway, improve neurologic outcomes, reduce brain edema and neuronal apoptosis. In summary, our findings suggest that 6-gingerol could attenuate EBI post-SAH in rats, and 6-gingerol may serve as a novel candidate neuroprotective drug for SAH-induced EBI.

Microclots in subarachnoid hemorrhage: an underestimated factor in delayed cerebral ischemia?

Subarachnoid hemorrhage has a poor prognosis due to the wide array of associated complications such as vasospasm, early brain injury, cortical spreading depression, oxidative stress, inflammation, and apoptosis. Each of these complications increases the risk of delayed cerebral ischemia (DCI), but recent research has suggested microclots play a substantial role in DCI incidence. This review will focus on the underlying inflammatory and coagulative mechanisms of microthrombosis while also outlining the current literature relating microclot burden to DCI. With a better understanding DCI pathophysiology as it relates to microthrombosis, more effective therapies can be developed in the future to improve clinical outcomes of SAH.

Preclinical and clinical role of interleukin-6 in the development of delayed cerebral vasospasm and neuronal cell death after subarachnoid hemorrhage: towards a potential target therapy?

Delayed cerebral vasospasm (DCVS), early brain injury (EBI), and delayed cerebral ischemia (DCI) are devastating complications after aneurysmal subarachnoid hemorrhage (SAH). Interleukin (IL)-6 seems to be an important interleukin in the inflammatory response after SAH, and many studies describe a strong correlation between IL-6 and worse outcome. The aim of this study was to systematically review preclinical and clinical studies that evaluated systemic and cerebral IL-6 levels after SAH and their relation to DCVS, neuronal cell death, and DCI. We conducted two systematic literature searches using PubMed to identify preclinical and clinical studies evaluating the role of IL-6 after SAH. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 61 and 30 preclinical and clinical articles, respectively, were included in the systematic reviews. Of the preclinical studies in which IL-6 was measured in cerebrospinal fluid (CSF), parenchyma, and systemically, 100%, 94.4%, and 81.3%, respectively, showed increased expression of IL-6 after SAH. Preclinical results were mirrored by clinical findings in which elevated levels of IL-6 in CSF and plasma were found after SAH, correlating with DCVS, DCI, and worse outcome. Only two preclinical studies analyzed the direct inhibition of IL-6, which resulted in reduced DCVS and neuronal cell death. IL-6 is a marker of intracranial inflammation and plays a role in the pathophysiology of DCVS and DCI after SAH in preclinical animal models and clinical studies. Its inhibition might have therapeutic potential to improve the outcome of SAH patients.

Agonism of the α7-acetylcholine receptor/PI3K/Akt pathway promotes neuronal survival after subarachnoid hemorrhage in mice

Subarachnoid hemorrhage (SAH) results in severe neuronal dysfunction and degeneration. Since the nicotinic acetylcholine α₇ receptors (α₇-AChR) are involved in neuronal function and survival, we investigated if stimulation of α₇-AChR would promote neuronal survival and improve behavioral outcome following SAH in mice. Male mice subjected to SAH were treated with either galantamine (α₇-AChR agonist) or vehicle. Neurobehavioral testing was performed 24 h after SAH, and mice were euthanized for analysis of neuronal cell death or a cell survival (PI3K/Akt) signaling pathway. Neuron cell cultures were subjected to hemoglobin toxicity to assess the direct effects of α₇-AChR agonism independent of other cells. Treatment with the α₇-AChR agonist promoted neuronal survival and improved functional outcomes 24 h post-SAH. The improved outcomes corresponded with increased PI3K/Akt activity. Antagonism of α₇-AChR or PI3K effectively reversed galantamine's beneficial effects. Tissue from α₇-AChR knockout mice confirmed α₇-AChR's role in neuronal survival after SAH. Data from the neuronal cell culture experiment supported a direct effect of α₇-AChR agonism in promoting cell survival. Our findings indicate that α₇-AChR is a therapeutic target following SAH which can promote neuronal survival, thereby improving neurobehavioral outcome. Thus, the clinically relevant α₇-AChR agonist, galantamine, might be a potential candidate for human use to improve outcome after SAH.

Interleukin 6 and Aneurysmal Subarachnoid Hemorrhage. A Narrative Review

Interleukin 6 (IL-6) is a prominent proinflammatory cytokine. Neuroinflammation in general, and IL-6 signaling in particular, appear to play a major role in the pathobiology and pathophysiology of aneurysm formation and aneurysmal subarachnoid hemorrhage (SAH). Most importantly, elevated IL-6 CSF (rather than serum) levels appear to correlate with delayed cerebral ischemia (DCI, “vasospasm”) and secondary (“vasospastic”) infarctions. IL-6 CSF levels may also reflect other forms of injury to the brain following SAH, i.e., early brain damage and septic complications of SAH and aneurysm treatment. This would explain why many researchers have found an association between IL-6 levels and patient outcomes. These findings clearly suggest CSF IL-6 as a candidate biomarker in SAH patients. However, at this point, discrepant findings in variable study settings, as well as timing and other issues, e.g., defining proper clinical endpoints (i.e., secondary clinical deterioration vs. angiographic vasospasm vs. secondary vasospastic infarct) do not allow for its routine use. It is also tempting to speculate about potential therapeutic measures targeting elevated IL-6 CSF levels and neuroinflammation in SAH patients. Corticosteroids and anti-platelet drugs are indeed used in many SAH cases (not necessarily with the intention to interfere with detrimental inflammatory signaling), however, no convincing benefit has been demonstrated yet. The lack of a robust clinical perspective against the background of a relatively large body of data linking IL-6 and neuroinflammation with the pathophysiology of SAH is somewhat disappointing. One underlying reason might be that most relevant studies only report correlative data. The specific molecular pathways behind elevated IL-6 levels in SAH patients and their various interactions still remain to be delineated. We are optimistic that future research in this field will result in a better understanding of the role of neuroinflammation in the pathophysiology of SAH, which in turn, will translate into the identification of suitable biomarkers and even potential therapeutic targets.

Pharmaceutical Management for Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage can have deleterious consequences. Vasospasm, delayed cerebral ischemia, and re-hemorrhage can all cause delayed sequelae. Furthermore, severe headaches are common and require careful modulation of pain medications. Limited treatment options currently exist and are becoming more complex with the rising use of oral anticoagulants needing reversal. In this review, we highlight the current treatment options currently employed and address avenues of future discovery based on emerging preclinical data. Furthermore, we dive into the best treatment approach for managing headaches following subarachnoid hemorrhage. The review is designed to serve as a catalyst for further prospective investigation into this important topic.

Interleukin-6: Important Mediator of Vasospasm Following Subarachnoid Hemorrhage

The correlation of neuroinflammation with the development of cerebral vasospasm following subarachnoid hemorrhage has been well documented in the literature; both clinical and preclinical. The exact mechanisms by which this process occurs, however, are poorly elucidated. Recent evidence indicates that interleukin-6 is not only an important prognostic biomarker for subarachnoid hemorrhage and subsequent vasospasm development but also an integral component in the progression of injury following initial insult. In this review, we briefly highlight other pathways under investigation and focus heavily on what has been discovered regarding the role of interleukin 6 and cerebral vasospasm following subarachnoid hemorrhage. A proposed mechanistic pathway is highlighted in written and graphical format. A discussion regarding the human correlative findings and initial pre-clinical mechanistic studies is addressed. Finally, in the future investigation section, innovative developments and a clear description of areas warranting further scientific inquiry are emphasized. This review will catalyze continued discovery in this area of emerging significance and aid in the quest for effective vasospasm treatment where limited clinical therapeutics currently exist.