Post Intracerebral Hemorrhage Research Articles

Single-cell RNA sequencing reveals the evolution of the immune landscape during perihematomal edema progression after intracerebral hemorrhage

BackgroundPerihematomal edema (PHE) after post-intracerebral hemorrhage (ICH) has complex pathophysiological mechanisms that are poorly understood. The complicated immune response in the post-ICH brain constitutes a crucial component of PHE pathophysiology. In this study, we aimed to characterize the transcriptional profiles of immune cell populations in human PHE tissue and explore the microscopic differences between different types of immune cells.Methods9 patients with basal ganglia intracerebral hemorrhage (hematoma volume 50-100 ml) were enrolled in this study. A multi-stage profile was developed, comprising Group1 (n = 3, 0–6 h post-ICH, G1), Group2 (n = 3, 6–24 h post-ICH, G2), and Group3 (n = 3, 24–48 h post-ICH, G3). A minimal quantity of edematous tissue surrounding the hematoma was preserved during hematoma evacuation. Single cell RNA sequencing (scRNA-seq) was used to map immune cell populations within comprehensively resected PHE samples collected from patients at different stages after ICH.ResultsWe established, for the first time, a comprehensive landscape of diverse immune cell populations in human PHE tissue at a single-cell level. Our study identified 12 microglia subsets and 5 neutrophil subsets in human PHE tissue. What’s more, we discovered that the secreted phosphoprotein-1 (SPP1) pathway served as the basis for self-communication between microglia subclusters during the progression of PHE. Additionally, we traced the trajectory branches of different neutrophil subtypes. Finally, we also demonstrated that microglia-produced osteopontin (OPN) could regulate the immune environment in PHE tissue by interacting with CD44-positive cells.ConclusionsAs a result of our research, we have gained valuable insight into the immune-microenvironment within PHE tissue, which could potentially be used to develop novel treatment modalities for ICH.

Nutrition markers and discharge outcome in deep and lobar intracerebral hemorrhage.

Malnutrition is common in stroke patients and has been associated with poor functional outcomes and increased mortality after stroke. Previous research on nutrition status and post-intracerebral hemorrhage (ICH) outcomes, however, is limited and conflicting. Monocenter study of patients with spontaneous deep or lobar ICH from a longitudinal cohort enrolling consecutive patients between 1994 and 2022. Nutrition status was assessed using admission body mass index (BMI), albumin, total bilirubin, cholesterol, c-reactive protein, hemoglobin a1c, high-density lipoprotein, hemoglobin, low-density lipoprotein, mean corpuscular volume, alanine transaminase, and triglycerides. Main outcome was favorable discharge outcome (mRS 0-2). Multivariable logistic regression was conducted with adjustment for baseline differences. Among 2170 patients, 1152 had deep and 1018 had lobar ICH. Overweight BMI was associated with higher odds of favorable discharge outcome in all (aOR = 3.01, 95% CI 1.59-5.69, p = 0.001) and lobar (aOR = 3.26, 95% CI 1.32-8.08, p = 0.011) ICH after adjustment for baseline differences. This association did not reach statistical significance in deep (aOR = 2.77, 95% CI 0.99-7.72, p = 0.052) ICH. No lab values were associated with functional outcome in all, deep, or lobar ICH after adjustment. Overweight BMI was associated with favorable discharge status after ICH. These findings could inform future studies to determine whether overweight BMI has a protective effect in ICH patients.

Itaconate protects ferroptotic neurons by alkylating GPx4 post stroke.

Neuronal ferroptosis plays a key role in neurologic deficits post intracerebral hemorrhage (ICH). However, the endogenous regulation of rescuing ferroptotic neurons is largely unexplored. Here, we analyzed the integrated alteration of metabolomic landscape after ICH using LC-MS and MALDI-TOF/TOF MS, and demonstrated that aconitate decarboxylase 1 (Irg1) and its product itaconate, a derivative of the tricarboxylic acid cycle, were protectively upregulated. Deficiency of Irg1 or depletion of neuronal Irg1 in striatal neurons was shown to exaggerate neuronal loss and behavioral dysfunction in an ICH mouse model using transgenic mice. Administration of 4-Octyl itaconate (4-OI), a cell-permeable itaconate derivative, and neuronal Irg1 overexpression protected neurons in vivo. In addition, itaconate inhibited ferroptosis in cortical neurons derived from mouse and human induced pluripotent stem cells in vitro. Mechanistically, we demonstrated that itaconate alkylated glutathione peroxidase 4 (GPx4) on its cysteine 66 and the modification allosterically enhanced GPx4's enzymatic activity by using a bioorthogonal probe, itaconate-alkyne (ITalk), and a GPx4 activity assay using phosphatidylcholine hydroperoxide. Altogether, our research suggested that Irg1/itaconate-GPx4 axis may be a future therapeutic strategy for protecting neurons from ferroptosis post ICH.

CSF1R blockade slows progression of cerebral hemorrhage by reducing microglial proliferation and increasing infiltration of CD8 + CD122+ T cells into the brain

Microglia play a pivotal role in the neuroinflammatory response after brain injury, and their proliferation is dependent on colony-stimulating factors. In the present study, we investigated the effect of inhibiting microglia proliferation on neurological damage post intracerebral hemorrhage (ICH) in a mouse model, an aspect that has never been studied before. Using a colony-stimulating factor-1 receptor antagonist (GW2580), we observed that inhibition of microglia proliferation significantly ameliorated neurobehavioral deficits, attenuated cerebral edema, and reduced hematoma volume after ICH. This intervention was associated with a decrease in pro-inflammatory factors in microglia and an increased infiltration of peripheral regulatory CD8 + CD122+ T cells into the injured brain tissue. The CXCR3/CXCL10 axis is the mechanism of brain homing of regulatory CD8 + CD122+ T cells, and the high expression of IL-10 is the hallmark of their synergistic anti-inflammatory effect with microglia. And activated astrocytes around the insult site are a prominent source of CXCL10. Thus, inhibition of microglial proliferation offers a new perspective for clinical translation. The cross-talk between multiple cells involved in the regulation of the inflammatory response highlights the comprehensive nature of neuroimmunomodulation.

Human-induced pluripotent stem cell-derived neural stem cell exosomes improve blood-brain barrier function after intracerebral hemorrhage by activating astrocytes via PI3K/AKT/MCP-1 axis.

JOURNAL/nrgr/04.03/01300535-202502000-00029/figure1/v/2024-05-28T214302Z/r/image-tiff Cerebral edema caused by blood-brain barrier injury after intracerebral hemorrhage is an important factor leading to poor prognosis. Human-induced pluripotent stem cell-derived neural stem cell exosomes (hiPSC-NSC-Exos) have shown potential for brain injury repair in central nervous system diseases. In this study, we explored the impact of hiPSC-NSC-Exos on blood-brain barrier preservation and the underlying mechanism. Our results indicated that intranasal delivery of hiPSC-NSC-Exos mitigated neurological deficits, enhanced blood-brain barrier integrity, and reduced leukocyte infiltration in a mouse model of intracerebral hemorrhage. Additionally, hiPSC-NSC-Exos decreased immune cell infiltration, activated astrocytes, and decreased the secretion of inflammatory cytokines like monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, and tumor necrosis factor-α post-intracerebral hemorrhage, thereby improving the inflammatory microenvironment. RNA sequencing indicated that hiPSC-NSC-Exo activated the PI3K/AKT signaling pathway in astrocytes and decreased monocyte chemoattractant protein-1 secretion, thereby improving blood-brain barrier integrity. Treatment with the PI3K/AKT inhibitor LY294002 or the monocyte chemoattractant protein-1 neutralizing agent C1142 abolished these effects. In summary, our findings suggest that hiPSC-NSC-Exos maintains blood-brain barrier integrity, in part by downregulating monocyte chemoattractant protein-1 secretion through activation of the PI3K/AKT signaling pathway in astrocytes.

VASP, HCLS1, MSN, and EZR: Key molecular beacons in the pathophysiology of perihematomal edema Post-Intracerebral hemorrhage

Perihematomal edema (PHE) is one of the significant secondary cerebral damages, with the blood–brain barrier's integrity playing a pivotal role in its progression. Strengthening tight junction (TJ) proteins enhances blood–brain barrier integrity, yet the complex genetics behind brain edema remain not fully understood. Our research endeavors to uncover pivotal genes and their roles in brain edema following cerebral hemorrhage, and to investigate potential treatment strategies. By analyzing intracerebral hemorrhage (ICH) and control samples using the GSE216607 and GSE206971 datasets, we identified differentially expressed genes. Cross-referencing with the KEGG database, we aligned these genes with those related to tight junctions. Extensive enrichment analysis and protein interactions were performed to examine the expression and clinical significance of the identified genes. Our study employed the C57BL/6J mouse ICH model and qRT-PCR for key gene validation. Notably, VASP, HCLS1, MSN, and EZR, critical for tight junctions, showed increased expression post-ICH, emphasizing their significance in BBB upkeep and PHE progression. Drug validation indicated potential therapeutic effects of Testosterone enanthate, SELENIUM, and LY 294002 on tight junction-related genes. This study sheds light on the potential involvement of these genes in brain edema progression post-ICH, offering promising therapeutic targets. Further research is needed for deeper understanding.

Abstract TMP81: Effect of Post Thrombolytic Intracerebral Hemorrhage Volume on 90-day Outcomes in Acute Ischemic Stroke Patients

Background and Purpose: Post thrombolytic intracerebral hemorrhage (ICH) is associated with higher rate of death or disability in acute ischemic stroke patients. We investigated the relationship between post thrombolytic ICH volume and change in volume and death or disability at 90 days in acute ischemic stroke patients. Methods: We analyzed 110 patents recruited in the Safety Evaluation of 3K3A-APC in Ischemic Stroke (RHAPSODY) trial who received intravenous tissue plasminogen activator (tPA) followed by mechanical thrombectomy (if indicated) and 3K3A-APC or placebo. ICH volume was measured at Day 2 and Day 7 using susceptibility weighted sequence (SWI) on magnetic resonance imaging (MRI). We also calculated the post thrombolytic ICH volume change between Day 2 and Day 7. Outcomes were determined by using utility weighted modified Rankin scale (UW-mRs) at 90-days. We adjusted for age, gender, National Institute of Health Stroke Scale (NIHSS) score (<10,10-19 and ≥20), location of hemorrhage (single basal ganglia hemorrhage, single lobar, single cerebellum, and multiple sites hemorrhage) in multivariate regression analysis. Results: A total of 88 (80%) of 110 patients had post thrombolytic ICH (mean volume 28.3 ml ± SD 62ml). The strata of ICH volume were not associated with UW-mRs at 90 days: <20 cc (regression coefficient-0.05, p= 0.58), 20-39 cc (-0.23, p=0.15), or 40 cc (-0.33, p= 0.086) compared with no ICH after adjusting for potential confounders. Change in ICH volume mean volume 27.43ml ±59.01, 52 had increase in volume) between Day 2 and day 7 was not associated with UW-mRS at 90 days (regression coefficient -11.87, p= 0.796). Conclusions: We did not observe any independent effect of post thrombolytic ICH volume on death or disability in acute ischemic stroke patients. Strategies to prevent ICH expansion such as antifibrinolytic medications and reduction in ICH volume such as surgical evacuation may not reduce death or disability in acute ischemic stroke patients with post thrombolytic ICH.

Kv1.3 Blockade Alleviates White Matter Injury through Reshaping M1/M2 Phenotypes via the NF-κB Signaling Pathway after Intracerebral Hemorrhage.

White matter injury (WMI) in basal ganglia usually induces long-term disability post intracerebral hemorrhage (ICH). Kv1.3 is an ion channel expressed in microglia and induces neuroinflammation after ICH. Here, we investigated the functions and roles of Kv1.3 activation-induced inflammatory response in WMI and the Kv1.3 blockade effect on microglia polarization after ICH. Mice ICH model was constructed by autologous blood injection. The expression of Kv1.3 was measured using immunoblot, real-time quantitative polymerase chain reaction (RT-qPCR), and immunostaining assays. Then, the effect of administration of 5-(4-Phenoxybutoxy) psoralen (PAP-1), a selectively pharmacological Kv1.3 blocker, was investigated using open field test (OFT) and basso mouse score (BMS). RT-qPCR, immunoblot, and enzyme-linked immunosorbent assay (ELISA) were taken to elucidate the expression of pro-inflammatory or anti-inflammatory factors around hematoma. PAP-1's function in regulating microglia polarization was investigated using immunoblot, RT-qPCR, and immunostaining assays. The downstream PAP-1 signaling pathway was determined by RT-qPCR and immunoblot. Kv1.3 expression was increased in microglia around the hematoma significantly after ICH. PAP-1 markedly improved neurological outcomes and the WMI by reducing pro-inflammatory cytokine accumulation and upregulating anti-inflammatory factors. Mechanistically, PAP-1 reduces NF-κB p65 and p50 activation, thus facilitating microglia polarization into M2-like microglia, which exerts this beneficial effect. PAP-1 reduced pro-inflammatory cytokines accumulation and increased anti-inflammatory factors by facilitating M2-like microglia polarization via the NF-κB signaling pathway. Thus, the current study shows that the Kv1.3 blockade is capable of ameliorating WMI by facilitating M2-like phenotype microglia polarization after ICH.

LncRNA-SNHG3 promotes neuroinflammation post-intracerebral hemorrhage by regulating the miR-106b-5p/TXNIP axis

LncRNA-SNHG3 promotes neuroinflammation post-intracerebral hemorrhage by regulating the miR-106b-5p/TXNIP axis

H3K9 trimethylation dictates neuronal ferroptosis through repressing Tfr1

Spontaneous intracerebral hemorrhage (ICH) is a devastating disease with high morbidity and mortality worldwide. We have previously shown that ferroptosis contributes to neuronal loss in ICH mice. The overload of iron and dysfunction of glutathione peroxidase 4 (GPx4) promote neuronal ferroptosis post-ICH. However, how epigenetic regulatory mechanisms affect the ferroptotic neurons in ICH remains unclear. In the current study, hemin was used to induce ferroptosis in N2A and SK-N-SH neuronal cells to mimic ICH. The results showed that hemin-induced ferroptosis was accompanied by an increment of global level of trimethylation in histone 3 lysine 9 (H3K9me3) and its methyltransferase Suv39h1. Transcriptional target analyses indicated that H3K9me3 was enriched at the promoter region and gene body of transferrin receptor gene 1 (Tfr1) and repressed its expression upon hemin stimulation. Inhibition of H3K9me3 with inhibitor or siRNA against Suv39h1 aggravated hemin- and RSL3-induced ferroptosis by upregulating Tfr1 expression. Furthermore, Suv39h1-H3K9me3 mediated repression of Tfr1 contributes to the progression of ICH in mice. These data suggest a protective role of H3K9me3 in ferroptosis post ICH. The knowledge gained from this study will improve the understanding of epigenetic regulation in neuronal ferroptosis and shed light on future clinical research after ICH.

Derivation and validation of a composite scoring system (SAVED2) for prediction of unfavorable modified Rankin scale score following intracerebral hemorrhage.

To develop a composite score for predicting functional outcome post-intracerebral hemorrhage (ICeH) using proxy measures that can be assessed retrospectively. Data from the observational ERICH study were used to derive a composite score (SAVED2) to predict an unfavorable 90-day modified Rankin scale (mRS) score. Independent predictors of unfavorable mRS were identified via multivariable logistic regression and assigned score weights based on effect size. Area under the curve (AUC) was used to measure the score's discriminative ability. External validation was performed in the randomized ATACH-2 trial. There were 2,449 patients from ERICH with valid mRS data who survived to hospital discharge. Predictors associated with unfavorable 90-day mRS score and their corresponding point values were: age ≥70 years (odds ratio [OR], 3.8; 1-point); prior stroke (OR, 2.8; 1-point); need for ventilation (OR, 2.7; 1-point); extended hospital stay (OR, 2.7; 1-point); and non-home discharge location (OR, 5.3; 2-points). Incidence of unfavorable 90-day mRS increased with higher SAVED2 scores (P < 0.001); AUC in ERICH was 0.82 (95% CI, 0.80-0.84). External validation in ATACH-2 (n = 904) found an AUC of 0.74 (95% CI, 0.70-0.77). Using data collected at hospital discharge, the SAVED2 score predicted unfavorable mRS in patients with ICeH.

Abstract TP130: Effect Of Antifibrinolytic Medication On Hematoma Expansion In Acute Ischemic Stroke Patients With Post Thrombolytic Intracerebral Hemorrhages

Background and Purpose: Antifibrinolytic medications such as the synthetic lysine analogs tranexamic acid and ε-aminocaproic acid inhibit fibrinolysis by attaching to the lysine-binding site of the plasminogen molecule. However, the efficacy of intravenous (IV) antifibrinolytic medication in the prevention of hematoma expansion in acute ischemic stroke patients who develop post thrombolytic intracerebral hemorrhage (ICH) is unclear. Methods: We analyzed the effect of antifibrinolytic medication in acute ischemic stroke patients with post thrombolytic ICH on hematoma expansion over an 8-year period. The Region-of-Interest; method on a Horos Medical Image Viewer (Version 3.3.6) was utilized for hematoma volume measurement on serial computed tomographic scans. We compared changes in hemorrhage volume in patients who did and did not receive IV antifibrinolytic medication. Results: A total of 53 patients (mean age 69.7±14.3, 53% were men) with post thrombolytic ICH were analyzed. Twenty-six patients received antifibrinolytic treatment: 20 and 6 patients received a single IV dose of ε-aminocaproic acid (5 g) or tranexamic acid (1 g), respectively. Ten patients (38%) had a reduction or stabilization in hematoma volume (overall pre and post-treatment volumes were 17.43±16.23 cm3 and 25.14±26.57 cm3 respectively). Mean fibrinogen level in the antifibrinolytic medication group was 277 mg/dL; 3 patients had levels &lt;200 mg/dL. In patients that did not receive antifibrinolytics, 16 (59%) out of 27 patients had a reduction or stabilization in hematoma volume (overall pre and post-treatment volumes were 19.74±32.32 cm3 and 27.15±52.58 cm3 respectively). The mean percent change in hematoma volume with antifibrinolytic medication treatment was 48% and without was 27%. [Figure 1] Conclusion: We did not identify any reduction in any of the measures of hematoma expansion with antifibrinolytic treatment in acute ischemic stroke patients with post thrombolytic ICH.

Inhibition of the LRRC8A channel promotes microglia/macrophage phagocytosis and improves outcomes after intracerebral hemorrhagic stroke.

Promoting microglial/macrophage (M/Mφ) phagocytosis accelerates hematoma clearance and improves the prognosis of intracerebral hemorrhagic stroke (ICH). Cation channels such as Piezo1 modulate bacterial clearance by regulating M/Mφ. Whether LRRC8A, an anion channel, affects M/Mφ erythrophagocytosis and functional recovery after ICH was investigated here. We found that LRRC8A is highly expressed on M/Mφ in the perihematomal region of ICH mice. Conditional knockout of Lrrc8a in M/Mφ or treatment with an LRRC8A channel blocker accelerated hematoma clearance, reduced neuronal death, and improved functional recovery after ICH. Mechanistically, the LRRC8A channel inhibition promoted M/Mφ phagocytosis by activating AMP-activated protein kinase (AMPK), thereby inducing nuclear translocation of nuclear factor-erythroid 2 related factor 2 (Nrf2) and increasing Cd36 transcription. Our findings illuminate the regulation of M/Mφ phagocytosis by the LRRC8A channel via the AMPK-Nrf2-CD36 pathway after ICH, suggesting that LRRC8A is a potential target for hematoma clearance in ICH treatment.

Colchicine pre-treatment and post-treatment does not worsen bleeding or functional outcome after collagenase-induced intracerebral hemorrhage.

Patients with intracerebral hemorrhage (ICH) are at increased risk for major ischemic cardiovascular and cerebrovascular events. However, the use of preventative antithrombotic therapy can increase the risk of ICH recurrence and worsen ICH-related outcomes. Colchicine, an anti-inflammatory agent, has the potential to mitigate inflammation-related atherothrombosis and reduce the risk of ischemic vascular events. Here we investigated the safety and efficacy of colchicine when used both before and acutely after ICH. We predicted that daily colchicine administration would not impact our safety measures but would reduce brain injury and improve functional outcomes associated with inflammation reduction. To test this, 0.05 mg/kg colchicine was given orally once daily to rats either before or after they were given a collagenase-induced striatal ICH. We assessed neurological impairments, intra-parenchymal bleeding, Perls positive cells, and brain injury to gauge the therapeutic impact of colchicine on brain injury. Colchicine did not significantly affect bleeding (average = 40.7 μL) at 48 hrs, lesion volume (average = 24.5 mm3) at 14 days, or functional outcome (median neurological deficit scale score at 2 days post-ICH = 4, i.e., modest deficits) from 1-14 days after ICH. Colchicine reduced the volume of Perls positive cells in the perihematomal zone, indicating a reduction in inflammation. Safety measures (body weight, food consumption, water consumption, hydration, body temperature, activity, and pain) were not affected by colchicine. Although colchicine did not confer neuroprotection or functional benefit, it was able to reduce perihematomal inflammation after ICH without increasing bleeding. Thus, our findings suggest that colchicine treatment is safe, unlikely to worsen bleeding, and is unlikely but may reduce secondary injury after an ICH if initiated early post ICH to reduce the risk of ischemic vascular events. These results are informative for the ongoing CoVasc-ICH phase II randomized trial (NCT05159219).

Allostatic load predicts racial disparities in intracerebral hemorrhage cognitive outcomes

A large portion of stroke disparities remains unexplained, even after adjusting for demographic, comorbidity, and health care access variables. There is a critical need to close this knowledge gap by investigating novel factors that may contribute to stroke disparities. Allostatic load (AL) is the lifetime adverse physiologic impact of needing to adjust to socially structured stressors such as racism. AL has been shown to increase health vulnerability and worsen outcomes in marginalized populations. We sought to assess the differential impact of AL on cognitive outcomes post intracerebral hemorrhage (ICH) across race-ethnicity. The Intracerebral Hemorrhage Outcomes Project (ICHOP) prospectively collected data from patients presenting to Columbia Medical Center with ICH from 3/2009 to 5/2016. Data included demographics, stroke scores, labs, complications, neuroimaging, medical history, and discharge data. Five markers of AL (HbA1c, WBC, SBP, HR, ALB) were obtained. An AL score was generated by summing the elements in each patient that fell outside normal ranges, with AL score ranging 0–5. A linear regression model, adjusted for stroke severity and ICH volumes, was used to evaluate the relationship between AL and Modified Telephone Interview for Cognitive Status (TICS-m) at discharge, stratified by race-ethnicity. Among 248 white, 195 black, and 261 Hispanic ICH patients, neither mean AL nor mean TICS differed by race/ethnicity (p = 0.51, p = 0.79 respectively). In the overall cohort AL did not predict TICS at discharge (Beta -1.0, SE 1.1, p = 0.353). In Whites (beta 1.18, SE 2.5, p = 0.646) and Hispanics (beta -0.95, SE 1.6, p = 0.552) AL was not associated with TICS at discharge. In Black patients, higher AL was associated with a decrease in TICS at discharge (beta -3.2, SE 1.5, p = 0.049). AL is an important determinant of post ICH outcomes for certain minority populations. AL may explain some of the unexplained health disparities in stroke populations.

Leptin Promotes Angiogenesis via Pericyte STAT3 Pathway upon Intracerebral Hemorrhage.

Angiogenesis is a vital endogenous brain self-repair processes for neurological recovery after intracerebral hemorrhage (ICH). Increasing evidence suggests that leptin potentiates angiogenesis and plays a beneficial role in stroke. However, the proangiogenic effect of leptin on ICH has not been adequately explored. Moreover, leptin triggers post-ICH angiogenesis through pericyte, an important component of forming new blood vessels, which remains unclear. Here, we reported that exogenous leptin infusion dose-dependent promoted vascular endothelial cells survival and proliferation at chronic stage of ICH mice. Additionally, leptin robustly ameliorated pericytes loss, enhanced pericytes proliferation and migration in ICH mice in vivo, and in ICH human brain microvascular pericytes (HBVPC) in vitro. Notably, we showed that pericytes-derived pro-angiogenic factors were responsible for enhancing the survival, proliferation and tube formation followed leptin treatment in human brain microvascular endothelial cells (HCMEC/D3)/HBVPC co-culture models. Importantly, considerable improvements in neurobehavioral function and hostile microenvironment were observed in leptin treatment ICH mice, indicating that better vascular functionality post ICH improves outcome. Mechanistically, this study unveiled that leptin boost post-ICH angiogenesis potentially through modulation of leptin receptor (leptinR)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway in pericyte. Thus, leptin may be a lucrative option for the treatment of ICH.

Brain-derived programmed death-ligand 1 mediates immunosuppression post intracerebral hemorrhage

Immunosuppression commonly occurs after a stroke, which is believed to be associated with the increased risk of infectious comorbidities of stroke patients, while the mechanisms underlying post-stroke immunosuppression is yet to be elucidated. In the brains of intracerebral hemorrhage (ICH) patients and murine ICH models, we identified that neuron-derived programmed death-ligand 1 (PD-L1) is reduced in the perihematomal area, associating increased soluble PD-L1 level in the peripheral blood. ICH induced a significant decrease of T and natural killer (NK) cell numbers in the periphery with an upregulation of programed death-1 (PD-1) in these cells. Blocking PD-1 pathway with an anti-PD1 monoclonal antibody prevented the T and NK cell compartment contraction and spleen atrophy post-ICH, with reduced pulmonary bacterial burden and improved neurological outcome. Thus, we here identified that brain-derived PD-L1 as a new mechanism driving post-stroke immunosuppression, and anti-PD1 treatment could be potentially developed to reducing the risk of post-stroke infections.

Managing Uncertainty: Physicians' Decision Making for Stroke Prevention for Patients with Atrial Fibrillation and Intracerebral Hemorrhage.

Stroke prevention in patients with atrial fibrillation (AF) post-intracerebral hemorrhage (ICH) is an area of clinical equipoise. Little is known about the tools and processes that physicians use to make decisions regarding anticoagulation in this high-risk patient population. To explore physicians' decision-making process regarding stroke prevention in patients with AF and a recent history of ICH. Qualitative study, utilizing semistructured interviews and analyzed using Framework analysis. Twenty physicians from five European countries (Austria, France, Germany, Spain, United Kingdom) participated. The overarching theme "Managing uncertainty," addressed the process of making high-risk clinical decisions in the context of little available robust clinical evidence for best practice. Three subthemes were identified under the umbrella theme: (1) "Computing the risks," captured the challenge of balancing the risks of ischemic stroke with the risk of recurrent ICH in a complex patient population; (2) "Patient factors" highlighted the influence that physician-perceived patients' beliefs and previous experience of stroke had on physicians' decisions; and (3) "Making a decision" explored the process of reaching a final decision regarding initiation of OAC therapy or not. Physicians described the process of deciding on stroke prevention in patients with AF post-ICH as "challenging" due to considerable "clinical equipoise." Key factors that affected decision making were patient comorbidities, functional status, and patient willingness to engage with OAC therapy. Shared decision making was believed to be beneficial, but physicians believed that the ultimate responsibility to decide on stroke prevention lay with the clinician.

Abstract 98: Brain-Derived Programmed Death-Ligand 1 Induces Post-Stroke Immunosuppression

Background and purpose: Post-stroke immunosuppression is associated with increased infection risk and mortality of stroke patients. However, the mechanisms driving post-stroke immunosuppression are not fully elucidated and strategies to prevent this fatal complication are lacking. We investigated the role of programmed death-ligand 1 (PD-L1) on post-stroke lymphocyte deficiency in a murine model of intracerebral hemorrhage (ICH). Methods: ICH was induced by intracerebral injection of autologous blood or collagenase IV to male C57BL/6 (B6) mice. Mice were randomly assigned into two groups to received anti-PD-1 antibody and vehicle respectively via intraperitoneal injection operating at 1 hour after ICH. Neurological function assessment, immunofluorescence, Elisa, flow cytometry, lung colony calculated were analyzed. Results: In a mice model of ICH, we identified that neuron-derived programmed death ligand 1 (PD-L1) are downregulated and released to the blood post ICH. Increased PD-L1 induced T cell and NK cell deficiency via their expressed PD-1, which are associated with increased lung infection post-ICH. Blocking PD-L1 pathway via an anti-PD-1 monoclonal antibody prevented the spleen atrophy of ICH mice, and improved peripheral T and NK cell numbers and function. Anti PD-1 antibody treated mice showed improved clinical outcome and reduced pulmonary bacterial burden. Conclusions: This study identified brain-derived PD-L1 to the periphery as a new pathway that lead to post-stroke immunosuppression, targeting PD-L1 could be a potential treatment strategy to reduce post-stroke infection risk. Key words: Programmed death ligand 1,intracerebral hemorrhage, neuron,immunosuppression, inflammation Short title: PD-L1 and post-stroke immunosuppression

Abstract TP131: Association Of Hemoglobin Over The First Week With Clinical Outcomes And Neuroimaging Characteristics In Patients With Spontaneous Intracerebral Hemorrhage

Introduction: Studies have shown independent associations of lower admission hemoglobin (HB) levels with larger spontaneous intracerebral hemorrhage (ICH) volumes and poor outcomes, possibly mediated by hematoma expansion (HE). Objective: We retrospectively investigated the association of HB levels over the first week post ICH with functional outcomes (FO) and neuroimaging findings in patients with spontaneous ICH (&gt;30 mL). We explored whether comorbidities modify the effects of HB. Methods: We analyzed HB levels from subjects enrolled in the Minimally Invasive Surgery Plus Alteplase for Intracerebral Hemorrhage Evacuation phase 3 trial (MISTIE III). The exposure was admission HB and the HB nadir in the first week. The primary outcome was good FO at 180 days, defined as modified Rankin Scale of 0-3. Secondary outcomes were good FO at 365 days, 30-day mortality, admission ICH volume, and HE (&gt;6 mL). Linear and logistic regression models were used to test the association of HB with clinical outcomes and neuroimaging findings. All models were adjusted for age, sex, race, treatment (medical Vs. MISTIE), Glasgow Coma Scale, ICH volume, presence of intraventricular hemorrhage, and ICH location (deep Vs. lobar). We investigated effect modification of comorbidities on association of HB with FO. Results: A total of 493 of 499 enrolled patients (61% males, mean age 61(SD=12) years, median ICH volume 41.8 (IQR=30.8-51.5) mL) were included. Patients with good FO at 180 days had a higher admission HB (13.2 Vs. 12.6 g/dl, p=0.001) and a higher nadir HB (11.7 Vs. 10.9 g/dl, p&lt;0.001). In adjusted analyses, each additional g/dl in nadir HB (but not admission HB) was associated with higher odds of good FO at 180 (OR 1.29, p=0.005) and 365 (OR 1.18, P=0.048) days. Baseline (B= -1.16, p=0.02) and nadir HB (B= -1.71, p=0.001) were inversely associated with hematoma volumes, but not with HE. There was evidence of heterogeneity in the effects of diabetes on the association of nadir HB with day 180 FO (OR 0.67; p interaction = 0.045). Conclusions: In patients with ICH &gt; 30 mL, higher nadir HB in the first week was associated with better long-term FO and smaller ICH volumes, but not with HE. Early hemoglobin changes may serve as a prognostic biomarker and a potentially modifiable factor to improve FO.