Neuroinflammation evoked by brain injury in a rat model of lacunar infarct

Causal relationship of inflammatory cytokines and serum metabolites in cerebral small vessel disease: a two-step Mendelian randomization study

BACKGROUND AND PURPOSE

The aim was to investigate the causal relationships of inflammatory cytokines and serum metabolites in cerebral small vessel disease (CSVD).

METHODS

Bidirectional Mendelian randomization was first conducted to screen inflammatory cytokines and serum metabolites that were associated with imaging features of CSVD, including white matter hyperintensities, recent small subcortical infarcts, cortical cerebral microinfarcts, cerebral microbleeds, lacunes and enlarged perivascular spaces. Sensitivity analyses were performed to evaluate the robustness and pleiotropy of these results. Subsequently, inflammatory cytokines and serum metabolites that were associated with CSVD were subjected to functional enrichment. Finally, mediation analysis was employed to investigate whether inflammatory cytokines or serum metabolites acted as an intermediary for the other in their causal relationship with CSVD.

RESULTS

Of the inflammatory cytokines, five were risk factors (e.g., tumour-necrosis-factor-related apoptosis-inducing ligand) and five (e.g., fibroblast growth factor 19) were protective factors for CSVD. Eleven serum metabolites that increased CSVD risk and 13 metabolites that decreased CSVD risk were also identified. The majority of these markers of CSVD susceptibility were lipid metabolites. Natural killer cell receptor sub-type 2B4 was determined to act as a mediating factor of an unidentified metabolite for the enlargement of perivascular spaces.

CONCLUSION

Several inflammatory cytokines and serum metabolites had causal relationships with imaging features of CSVD. A natural killer cell receptor mediated in part the promotional effect of a metabolite on perivascular space enlargement.

Opportunities for developing neural stem cell treatments for acute ischemic stroke: A systematic review and gap analysis

Ischemic stroke is a leading cause of disability and death. Current treatments are limited. Stem cell therapy has been highlighted as a potentially effective treatment to mitigate damage and restore function, but efficacy results are mixed. This study aimed to systematically review the literature on stem cell therapies for early acute ischemic stroke; and identify opportunities for future research to facilitate the development of an effective stem cell-based treatment. Original research published within the last 10 years that focused on the evaluation of a stem cell-based treatment for acute ischemic stroke in adult patients or subjects was included. Risk of bias was assessed using the SYRCLE and Cochrane risk of bias tools for animal and human studies, respectively. 3,396 articles were screened, 58 full-text articles were reviewed and 33 met inclusion criteria. Many studies appeared to be at risk of bias. Study designs and results were heterogeneous. Most studies were preclinical and involved stem cell administration within 24 hours. Seven studies tested the effects of multiple administration timepoints and one investigated repeat dosing. Six studies were conducted in humans and stem cell administration ranged from 24 hours to 90 days post stroke. Most studies employed the use of mesenchymal stem cells. The most appropriate cell delivery method appeared to be intra-arterial. Evidence suggests that stem cell therapy may be associated with beneficial effects. A literature gap analysis identified numerous opportunities for treatment development.

Unraveling the Role of miR-200b-3p in Attention-Deficit/Hyperactivity Disorder (ADHD) and Its Therapeutic Potential in Spontaneously Hypertensive Rats (SHR)

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder in children with unknown etiology. Impaired learning ability was commonly reported in ADHD patients and has been associated with dopamine uptake in the striatum of an animal model. Another evidence also indicated that micro-RNA (miR)-200b-3p is associated with learning ability in various animal models. However, the association between miR-200b-3p and ADHD-related symptoms remains unclear. Therefore, the current study investigated the role of miR-200b-3p in ADHD-related symptoms such as inattention and striatal inflammatory cytokines. To verify the influence of miR-200b-3p in ADHD-related symptoms, striatal stereotaxic injection of miR-200b-3p antagomir (AT) was performed on spontaneously hypertensive rats (SHR). The antioxidant activity and expressions of miR-200b-3p, slit guidance ligand 2 (Slit2), and inflammatory cytokines in the striatum of SHR were measured using quantitative real-time polymerase chain reaction (RT-qPCR), immunohistochemistry (IHC), immunoblotting, and enzyme-linked immunosorbent assay (ELISA). The spontaneous alternation of SHR was tested using a three-arm Y-shaped maze. The administration of miR-200b-3p AT or taurine significantly decreased striatal tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in SHR, along with increased super-oxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and significantly higher spontaneous alternation. In this paper, we show that miR-200b-3p AT and taurine alleviates ADHD-related symptoms in SHR. These findings provide insights into ADHD's molecular basis and suggest miR-200b-3p as a potential therapeutic target. Concurrently, this study also suggests broad implications for treating neurodevelopmental disorders affecting learning activity such as ADHD.

Cerebral Small Vessel Disease: a Review of the Pathophysiological Mechanisms

Cerebral small vessel disease (cSVD) refers to the age-dependent pathological processes involving the brain small vessels and leading to vascular cognitive impairment, intracerebral hemorrhage, and acute lacunar ischemic stroke. Despite the significant public health burden of cSVD, disease-specific therapeutics remain unavailable due to the incomplete understanding of the underlying pathophysiological mechanisms. Recent advances in neuroimaging acquisition and processing capabilities as well as findings from cSVD animal models have revealed critical roles of several age-dependent processes in cSVD pathogenesis including arterial stiffness, vascular oxidative stress, low-grade systemic inflammation, gut dysbiosis, and increased salt intake. These factors interact to cause a state of endothelial cell dysfunction impairing cerebral blood flow regulation and breaking the blood brain barrier. Neuroinflammation follows resulting in neuronal injury and cSVD clinical manifestations. Impairment of the cerebral waste clearance through the glymphatic system is another potential process that has been recently highlighted contributing to the cognitive decline. This review details these mechanisms and attempts to explain their complex interactions. In addition, the relevant knowledge gaps in cSVD mechanistic understanding are identified and a systematic approach to future translational and early phase clinical research is proposed in order to reveal new cSVD mechanisms and develop disease-specific therapeutics.

The role of T cells in acute ischemic stroke

Acute ischemic stroke (AIS) is associated with high rates of disability and mortality, exerting a substantial impact on overall survival and health-related quality of life. Treatment of AIS remains challenging given that the underlying pathologic mechanisms remain unclear. However, recent research has demonstrated that the immune system plays a key role in the development of AIS. Numerous studies have reported infiltration of T cells into ischemic brain tissue. While some types of T cells can promote the development of inflammatory responses and aggravate ischemic damage in patients with AIS, other T cells appear to exert neuroprotective effects via immunosuppression and other mechanisms. In this review, we discuss the recent findings regarding the infiltration of T cells into ischemic brain tissue, and the mechanisms governing how T cells can facilitate tissue injury or neuroprotection in AIS. Factors influencing the function of T cells, such as intestinal microflora and sex differences, are also discussed. We also explore the recent research on the effect of non-coding RNA on T cells after stroke, as well as the potential for specifically targeting T cells in the treatment of stroke patients.

Periostin and TNF-α expression levels in peripheral blood of patients with acute cerebral infarction combined with obstructive sleep apnea syndrome and their predictive value for clinical prognosis

OBJECTIVE

To detect the expression levels of periostin and tumour necrosis factor-α (TNF-α) in patients with acute cerebral infarction (ACI) combined with obstructive sleep apnea syndrome (OSAS) and to investigate their predictive value for clinical prognosis.

METHODS

In this case‒control study, serum periostin and TNF-α levels were measured using ELISA, and patients were scored on the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS). Receiver operating characteristic curve(ROC) were generated to analyse the effect of peripheral blood periostin and TNF-α levels on poor prognosis.

RESULTS

NIHSS score, mRS score and peripheral blood periostin and TNF-α levels were higher in the observation group than in the control group (P < 0.001); serum periostin and TNF-α levels were positively correlated with the NIHSS score and mRS score (P < 0.001). Serum periostin and TNF-α levels were higher in patients with a poor prognosis than in those with a favourable prognosis (P < 0.001); the area under curve (AUC) values for the diagnosis of poor prognosis based on TNF-α, periostin or both factors were 0.868 (95% CI: 0.781-0.954), 0.834 (95% CI: 0.734-0.934), and 0.875 (95% CI: 0.792 ~ 0.958), with sensitivities of 0.654, 0.846, and 0.654 and specificities of 0.944, 0.750, and 0.917, respectively.

CONCLUSION

Patients with ACI combined with OSAS have elevated peripheral blood periostin and TNF-α levels, and the combination of these two factors has high predictive value for poor prognosis.

Al-buhadiliy A, De Waard M, Sabatier JM, Khan Khalil AA, Saad HM, Batiha GES. Role of Neuropilin 1 in COVID-19 Patients with Acute Ischemic Stroke

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection can trigger the adaptive and innate immune responses, leading to uncontrolled inflammatory reactions and associated local and systematic tissue damage, along with thromboembolic disorders that may increase the risk of acute ischemic stroke (AIS) in COVID-19 patients. The neuropilin (NRP-1) which is a co-receptor for the vascular endothelial growth factor (VEGF), integrins, and plexins, is involved in the pathogenesis of AIS. NRP-1 is also regarded as a co-receptor for the entry of SARS-CoV-2 and facilitates its entry into the brain through the olfactory epithelium. NRP-1 is regarded as a cofactor for binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2), since the absence of ACE2 reduces SARS-CoV-2 infectivity even in presence of NRP-1. Therefore, the aim of the present study was to clarify the potential role of NRP-1 in COVID-19 patients with AIS. SARS-CoV-2 may transmit to the brain through NRP-1 in the olfactory epithelium of the nasal cavity, leading to different neurological disorders, and therefore about 45% of COVID-19 patients had neurological manifestations. NRP-1 has the potential capability to attenuate neuroinflammation, blood-brain barrier (BBB) permeability, cerebral endothelial dysfunction (ED), and neuronal dysfunction that are uncommon in COVID-19 with neurological involvement, including AIS. Similarly, high NRP-1 serum level is linked with ED, oxidative stress, and the risk of pulmonary thrombosis in patients with severe COVID-19, suggesting a compensatory mechanism to overcome immuno-inflammatory disorders. In conclusion, NRP-1 has an important role in the pathogenesis of COVID-19 and AIS, and could be the potential biomarker linking the development of AIS in COVID-19. The present findings cannot provide a final conclusion, and thus in silico, experimental, in vitro, in vivo, preclinical, and clinical studies are recommended to confirm the potential role of NRP-1 in COVID-19, and to elucidate the pharmacological role of NRP-1 receptor agonists and antagonists in COVID-19.

Propofol rescued astrocytes from LPS-induced inflammatory response via blocking LncRNA-MEG3/NF-κB axis

OBJECTIVE

Evidences had demonstrated that propofol attenuated neuro-inflammation following brain ischemia. Moreover, LncRNA-MEG3 was identified as an independent prognostic marker for ischemic stroke patients, and was found to be correlated with cerebral ischemia in animal models. Therefore, the current study explored the role of propofol on lipopolysaccharide (LPS)-mediated inflammation in cultured astrocytes, along with the molecular mechanism involved in LncRNA-MEG3/NF-κB axis.

METHODS

The primary cultured astrocytes isolated from rats were used to establish an inflammatory model, which were treated with LPS. Propofol was administrated to the primary cultured astrocytes during LPS treatment. The effect of propofol on pro-inflammatory cytokines and the LncRNA-MEG3/NF-κB pathway were detected by ELISA, qRT-PCR and Western Blot assay, respectively. Then, dual-luciferase assay, chromatin immunoprecipitation and RNA immunoprecipitation were used to determine the interaction between LncRNA-MEG3 and NF-κB.

RESULTS

Our study found that propofol significantly reduced LncRNA-MEG3 expression, which was elevated in LPS-stimulated astrocytes. Moreover, both propofol and LncRNA-MEG3 knockdown remarkably alleviated LPS-induced cytotoxicity by suppressing expressions and release of pro-inflammatory cytokines. Loss of LncRNA-MEG3 notably suppressed the NF-κB activity and its phosphorylated activation. Additionally, it was also observed that LncRNA-MEG3 could bind nuclear p65/p50, and promote the binding of NF-κB to IL-6 and TNF-α promoters in the nucleus, subsequently stimulating the production of inflammatory cytokines in LPS-treated astrocytes. Furthermore, a specific inhibitor of NF-κB, PDTC rescued astrocytes from LPS exposure without affecting LncRNA-MEG3 expression.

CONCLUSION

These findings demonstrated that LncRNA-MEG3 acted as a positive regulator of NF-κB, mediated the neuroprotection of propofol in LPS-triggered astrocytes injury.