The Crosstalk Between Immune Cells After Intracerebral Hemorrhage

A prospective cohort study on serum PINK1 as a biochemical marker in relation to poor neurological prognosis, stroke-associated pneumonia and early neurological deterioration after acute intracerebral hemorrhage

BACKGROUND

PTEN-induced putative kinase 1 (PINK1) may moderate neurodegeneration via sustaining mitochondrial function and integrity. Here, we attempted to determine relationship between serum PINK1 levels, disease severity, poor prognosis, Early Neurological Deterioration (END) and Stroke-Associated Pneumonia (SAP) following acute Intracerebral Hemorrhage (ICH).

METHODS

Altogether, 175 patients with ICH and 80 controls were encompassed in this prospective cohort study. Serum PINK1 levels were measured at admission of all patients and at study entry of all controls. The National Institutes of Health Stroke Scale (NIHSS) scores and hematoma volumes were applied to determine the severity. SAP, END and post-ICH 6-month poor prognosis (modified Rankin Scale scores: 3-6) were recorded as the three outcome variables of interest.

RESULTS

Patients, in contrast to controls, had significantly elevated serum PINK1 levels. Serum PINK1 levels were independently correlated with NIHSS scores, hematoma volumes and 6-month modified Rankin Scale scores. Serum PINK1 levels were linearly correlated with risks of SAP, END and post-ICH 6-month poor prognosis under the restricted cubic spline, as well as along with NIHSS scores and hematoma volumes, became their independent predictors. As demonstrated under receiver operating characteristic curve, serum PINK1 levels displayed effective predictive ability and possessed similar discrimination efficiency, when compared to NIHSS scores and hematoma volumes. Using sensitivity analysis, prognosis association was robust.

CONCLUSION

Serum PINK1 levels are substantially heightened after ICH, and may accurately mirror hemorrhagic intensity and efficaciously forecast END, SAP, and poor neurological prognosis, signifying that PINK1 may be a serological prognosticator of good prospect in ICH.

Extracellular cold-inducible RNA-binding protein in CNS injury: molecular insights and therapeutic approaches

Central nervous system (CNS) injuries, such as ischemic stroke (IS), intracerebral hemorrhage (ICH) and traumatic brain injury (TBI), are a significant global burden. The complex pathophysiology of CNS injury is comprised of primary and secondary injury. Inflammatory secondary injury is incited by damage-associated molecular patterns (DAMPs) which signal a variety of resident CNS cells and infiltrating immune cells. Extracellular cold-inducible RNA-binding protein (eCIRP) is a DAMP which acts through multiple immune and non-immune cells to promote inflammation. Despite the well-established role of eCIRP in systemic and sterile inflammation, its role in CNS injury is less elucidated. Recent literature suggests that eCIRP is a pleiotropic inflammatory mediator in CNS injury. eCIRP is also being evaluated as a clinical biomarker to indicate prognosis in CNS injuries. This review provides a broad overview of CNS injury, with a focus on immune-mediated secondary injury and neuroinflammation. We then review what is known about eCIRP in CNS injury, and its known mechanisms in both CNS and non-CNS cells, identifying opportunities for further study. We also explore eCIRP's potential as a prognostic marker of CNS injury severity and outcome. Next, we provide an overview of eCIRP-targeting therapeutics and suggest strategies to develop these agents to ameliorate CNS injury. Finally, we emphasize exploring novel molecular mechanisms, aside from neuroinflammation, by which eCIRP acts as a critical mediator with significant potential as a therapeutic target and prognostic biomarker in CNS injury.

Noninvasive Vagus Nerve Stimulation Protects Neurons in the Perihematomal Region and Improves the Outcomes in a Rat Model of Intracerebral Hemorrhage

BACKGROUND

Intracranial hemorrhage (ICH) is a devastating stroke subtype with a high rate of mortality and disability. Therapeutic options available are primarily limited to supportive care and blood pressure control, whereas the surgical approach remains controversial. In this study, we explored the effects of noninvasive vagus nerve stimulation (nVNS) on hematoma volume and outcome in a rat model of collagenase-induced ICH.

METHODS

Adult male Wistar rats were randomized into two study groups: (1) ICH-treated (rats treated with five 2-min nVNS) and (2) ICH-control (ICH with sham nVNS). Each group received either a 0.1-U or a 0.2-U collagenase dose. After assessing neurological function, rats were euthanized at 24 h for spectrophotometric hemoglobin assay, hematoma volume measurements, and histological studies.

RESULTS

The ICH-treated group that received the 0.1-U collagenase dose demonstrated significantly smaller hematoma volume and improved motor function compared with the ICH-control with the same dose. Furthermore, the pooled data for the ICH-treated groups (both 0.1 U and 0.2 U of collagenase) revealed a reduction in neuronal loss in the perihematomal region in the histopathological studies. This effect was not significant for the group that received a 0.2-Ucollagenase dose.

CONCLUSIONS

nVNS therapy in acute settings may provide a neuroprotective effect and limit hematoma expansion in smaller volumes, improving neurological function post-ICH.

Immune Cells and Intracerebral Hemorrhage: A Causal Investigation Through Mendelian Randomization

BACKGROUND

The involvement of immune cells in the pathophysiology of intracerebral hemorrhage (ICH) is becoming increasingly recognized, yet their specific causal contributions remain uncertain. The objective of this research is to uncover the potential causal interactions between diverse immune cells and ICH using Mendelian randomization (MR) analysis.

METHODS

Genetic variants associated with 731 immune cell traits were sourced from a comprehensive genome-wide association study (GWAS) involving 3757 participants. Summary statistics data for ICH were acquired from FinnGen, comprising 4056 ICH cases and 371,717 controls. The principal analytical tool utilized in our study was the inverse-variance weighted (IVW) method, incorporated as a key component of a two-sample MR approach. To mitigate potential biases and verify the stability of the conclusions drawn from the primary analytical methods, a series of sensitivity analyses were performed.

RESULTS

MR analysis elucidated 33 immune cell traits with causal associations, comprising B cells (eight traits), conventional dendritic cells (cDC, two traits), maturation stages of T cells (two traits), monocytes (two traits), myeloid cells (five traits), TBNK cells (six traits), and regulatory T cells (Treg, eight traits). DP (CD4+CD8+) %T cell (OR = 0.83, CI = 0.72-0.96, p = 0.013) exhibited the strongest protective effect. In contrast, transitional AC (OR = 1.09, CI = 1.02-1.16, p = 0.006) and IgD- CD27- %lymphocyte (OR = 1.08, CI = 1.00-1.17, p = 0.045) showed a higher tendency to increase the ICH risk. The sensitivity analyses validated the robustness and consistency of these results.

CONCLUSION

Our research provides robust evidence substantiating the causal relationship between specific immunophenotypes and ICH risk. The identification of these findings significantly enhances our understanding of the pathogenic mechanisms underlying ICH, particularly pertaining to the immune system. This breakthrough paves the way for innovative clinical and pharmaceutical research opportunities, potentially promoting the development of targeted therapies and enhanced strategies for managing and preventing ICH.

ATP5J regulates microglial activation via mitochondrial dysfunction, exacerbating neuroinflammation in intracerebral hemorrhage

Microglial-mediated neuroinflammation is crucial in the pathophysiological mechanisms of secondary brain injury (SBI) following intracerebral hemorrhage (ICH). Mitochondria are central regulators of inflammation, influencing key pathways such as alternative splicing, and play a critical role in cell differentiation and function. Mitochondrial ATP synthase coupling factor 6 (ATP5J) participates in various pathological processes, such as cell proliferation, migration, and inflammation. However, the role of ATP5J in microglial activation and neuroinflammation post-ICH is poorly understood. This study aimed to investigate the effects of ATP5J on microglial activation and subsequent neuroinflammation in ICH and to elucidate the underlying mechanisms. We observed that ATP5J was upregulated in microglia after ICH. AAV9-mediated ATP5J overexpression worsened neurobehavioral deficits, disrupted the blood-brain barrier, and increased brain water content in ICH mice. Conversely, ATP5J knockdown ameliorated these effects. ATP5J overexpression also intensified microglial activation, neuronal apoptosis, and inflammatory responses in surrounding tissues post-ICH. ATP5J impaired microglial dynamics and reduced the proliferation and migration of microglia to injury sites. We used oxyhemoglobin (OxyHb) to stimulate BV2 cells and model ICH in vitro. Further in vitro studies showed that ATP5J overexpression enhanced OxyHb-induced microglial functional transformation. Mechanistically, ATP5J silencing reversed dynamin-related protein 1 (Drp1) and mitochondrial fission 1 protein (Fis1) upregulation in microglia post-OxyHb induction; reduced mitochondrial overdivision, excessive mitochondrial permeability transition pore opening, and reactive oxygen species production; restored normal mitochondrial ridge morphology; and partially restored mitochondrial respiratory electron transport chain activity. ATP5J silencing further alleviated OxyHb-induced mitochondrial dysfunction by regulating mitochondrial metabolism. Our results indicate that ATP5J is a key factor in regulating microglial functional transformation post-ICH by modulating mitochondrial dysfunction and metabolism, thereby positively regulate neuroinflammation. By inhibiting ATP5J, SBI following ICH could be prevented. Therefore, ATP5J could be a candidate for molecular and therapeutic target exploration to alleviate neuroinflammation post-ICH.

Predictive value of the dynamic systemic immune-inflammation index in the prognosis of patients with intracerebral hemorrhage: a 10-year retrospective analysis

Background and purpose

The systemic immune-inflammation index (SII) is a novel immune inflammatory marker which has been proven to have excellent predictive value for many diseases. The aim of this study was to investigate the predictive value of SII at different time points after admission for functional outcome at discharge in patients with intracerebral hemorrhage (ICH).

Methods

The clinical data of patients with ICH who were treated at a medical center for neurological diseases in China between October 2012 and April 2022 were analyzed in this retrospective study. The SII was calculated based on neutrophil×platelet/lymphocyte counts and collected within the first 14 days after admission to analyze the dynamic changes. Adverse outcome was defined as a modified Rankin Scale (mRS) score of 4-6 at discharge. The correlation between the SII and the outcome was assessed using univariate and multivariate logistic regression analyses. The ability of SII to predict outcome was evaluated by the area under the receiver operating characteristic (ROC) curve (AUC).

Results

A total of 1,569 patients with ICH were included, of whom 790 had adverse outcome (50.35%). The Univariate logistic regression analysis showed that SII at any time point within 14 days after admission was significantly associated with adverse outcome. In the multivariate logistic regression analysis, the SII within 7 days after admission was found to be an independent predictor of adverse functional outcome in ICH patients at discharge. The ROC curve demonstrated that compared to other time points, the SII on day 2 after admission exhibited stronger predictive power for the functional outcome of patients with ICH at discharge (AUC:0.733, 95%CI = 0.679-0.787) (sensitivity 47.09%, specificity 87.02%) (OR 1.074, 95%CI = 1.033-1.126, p = 0.001).

Conclusion

SII within 7 days after admission, especially on day 2, is independently associated with adverse functional outcome in ICH patients at discharge. This association could be utilized in clinical practice and warrants further investigation.

Immune-mediated disruption of the blood-brain barrier after intracerebral hemorrhage: Insights and potential therapeutic targets

AIMS

Intracerebral hemorrhage (ICH) is a condition that arises due to the rupture of cerebral blood vessels, leading to the flow of blood into the brain tissue. One of the pathological alterations that occurs during an acute ICH is an impairment of the blood-brain barrier (BBB), which leads to severe perihematomal edema and an immune response.

DISCUSSION

A complex interplay between the cells of the BBB, for example, pericytes, astrocytes, and brain endothelial cells, with resident and infiltrating immune cells, such as microglia, monocytes, neutrophils, T lymphocytes, and others accounts for both damaging and protective mechanisms at the BBB following ICH. However, the precise immunological influence of BBB disruption has yet to be richly ascertained, especially at various stages of ICH.

CONCLUSION

This review summarizes the changes in different cell types and molecular components of the BBB associated with immune-inflammatory responses during ICH. Furthermore, it highlights promising immunoregulatory therapies to protect the integrity of the BBB after ICH. By offering a comprehensive understanding of the mechanisms behind BBB damage linked to cellular and molecular immunoinflammatory responses after ICH, this article aimed to accelerate the identification of potential therapeutic targets and expedite further translational research.

Modulation of GPER1 alleviates early brain injury via inhibition of A1 reactive astrocytes activation after intracerebral hemorrhage in mice

Background

Early brain injury (EBI) caused by inflammatory responses in acute phase of Intracerebral hemorrhage (ICH) plays a vital role in the pathological progression of ICH. Increasing evidences demonstrate A1 reactive astrocytes are associated with the severity of EBI. G-protein coupled estrogen receptor 1 (GPER1) has been proved mediating the neuroprotective effects of estrogen in central nervous system (CNS) disease. However, whether GPER1 plays a protective effect on ICH and A1 reactive astrocytes activation is not well studied.

Methods

ICH model was established by infused the autologous whole blood into the right basal ganglia in wild type and GPER1 knockout mice. GPER1 specific agonist G1 and antagonist G15 were administered by intraperitoneal injection at 1 h or 0.5 h after ICH. Neurological function was detected on day 1 and day 3 by open field test and corner turn test following ICH. Besides, A1 reactive astrocytes were determined by immunofluorescence staining after ICH on day 3. To further identify the possible mechanism of GPER1 mediated neuroprotective effect, Western blot assays was performed after ICH on day 3.

Results

After ICH, G1 treatment alleviated mice neurobehavior deficits on day 1 and day 3. Meanwhile, G1 treatment also significantly reduced the GFAP positive astrocytes and the C3 positive cells after ICH. Interestingly, G15 reversed the protective effect of G1 on the neurobehavior of ICH mice. Meanwhile, the expression of GFAP+C3+ A1 reactive astrocytes were also reduced by activation of GPER1. Mechanistic studies indicated TLR4 and NF-κB mediated the neuroprotective effect of GPER1.

Conclusion

Generally, activation of GPER1 alleviated the EBI through inhibiting A1 reactive astrocytes activation via TLR4/NF-κB pathway after ICH in mice. Additionally, GPER1may be a promising target for ICH treatment.