Ischemic white matter injury and the consequent neuroimmune response can contribute to vascular cognitive impairment. The role of B cells in ischemic white matter injury is unclear. Here, we show that crosstalk between meningeal B cells and CNS-resident microglia exacerbates white matter injury and vascular cognitive impairment. The B cell population expands and is activated in the dura mater, correlating with worsened white matter damage and neuroinflammation, whereas B cell depletion alleviates myelin thinning and cognitive impairment following chronic cerebral hypoperfusion in adult male mice. Mechanistically, microglia recruit meningeal B cells via MIF-CD74/CXCR4 signaling, and B cells adopt an IgG-secreting phenotype. IgG-secreting B cells induce microglial ferroptosis through Fc gamma receptors. Our data show that B cells contribute to white matter injury and cognitive impairment. The role of B cells in vascular cognitive impairment is unclear. Here, the authors show a crosstalk between CNS border-associated B cells and parenchymal microglia, through MIFCD74/CXCR4 and IgG signaling, exacerbating white matter injury.

Ischemic white matter damage is a significant pathological feature of chronic cerebral hypoperfusion, leading to cognitive impairments. However, the underlying molecular mechanisms remain poorly understood. In this study, we identify a causal association between genetically predicted extracellular signal-regulated kinase 5 (ERK5) expression and higher white matter hyperintensity volume through druggable target screening, suggesting its potential as a therapeutic target for white matter damage. Using different animal models of white matter damage, we show that Erk5 expression is significantly upregulated in microglia following both ischemic and demyelinating injury, correlating with the severity of white matter damage. Mechanistically, Erk5 exacerbates white matter damage by promoting microglial ferroptosis through the phosphorylation of nuclear factor of activated T-cells, cytoplasmic 4 (Nfatc4), which subsequently activates the expression of cleft lip and palate transmembrane protein 1-like protein (Clptm1l), a lipid scramblase involved in ferroptosis. Pharmacological and genetic inhibition of Erk5 in microglia effectively mitigates oxidative stress, lipid peroxidation, and ferroptosis, leading to a reduction in white matter damage and improved cognitive function. These findings underscore the potential of targeting the Erk5-Nfatc4-Clptm1l axis as a therapeutic strategy for ischemic white matter damage. Our study offers valuable insights into the molecular pathways driving white matter damage and provides a framework for the clinical translation of Erk5 inhibitors in the treatment of ischemic white matter damage.

Physiological bilirubin exerts protective effects against ischemic stroke, but its role in post-stroke white matter injury (WMI) remains unclear. Here, through integrated epidemiological, genetic, and mechanistic studies, we demonstrate that mild elevation of serum bilirubin mitigates ischemic WMI by modulating B cell immunometabolism. Prospective cohort and Mendelian randomization analyses revealed an inverse association between bilirubin levels and WMI severity. In experimental models, bilirubin suppressed B cell activation and neuroinflammation by targeting transferrin receptor (TFRC), thereby reducing iron overload, restoring glucose metabolism, and improving mitochondrial homeostasis. Single-cell profiling further linked bilirubin-mediated B cell modulation to attenuated microglial activation via Fcγ receptor signaling. The existence of a bilirubin-B cell immunometabolism axis bridges preclinical findings with clinical relevance. Our findings establish bilirubin as a key immunometabolic checkpoint in B cells and propose TFRC blocking as a therapeutic strategy for ischemic WMI.

Neuroinflammation, encompassing both innate and adaptive immune responses, plays a crucial role in ischemic stroke. Although B lymphocytes are central to adaptive immunity, their contributions to ischemic stroke remain poorly understood. Here, we demonstrated that B lymphocytes accumulate in ischemic lesions, forming germinal center-like structures at the later stage after stroke, which mainly depended on in situ proliferation. This accumulation correlated with worsened neuroinflammation and ischemic injury, whereas B cell depletion reduced chronic brain damage during stroke. Mechanistically, microglia recruited B cells into ischemic lesions through MIF-CD74/CXCR4 signaling during the early phase of stroke, while IFN-related pathways in B cells further drove neuroinflammation and brain injury. Targeting these pathways markedly alleviated cerebral ischemia and inflammation. Our findings shed light on the role of B lymphocytes in stroke pathology and suggest promising new avenues for therapeutic intervention.

BACKGROUND:Chronic inflammatory demyelinating polyneuropathy (CIDP) presents a significant therapeutic challenge, with up to 15% of patients being refractory to first-line treatments. METHODS:Anti-B cell maturation antigen chimeric antigen receptor T (CAR-T) cell therapy was applied to two patients with highly relapsed and refractory CIDP, followed by safety and efficacy evaluation. Multi-omics analyses were performed on samples of peripheral blood mononuclear cells (PBMCs) collected before and after infusion. FINDINGS:Both patients had no severe adverse events and achieved drug-free remission within 6 months post-CAR-T therapy. Patient 1 experienced disease recurrence 12 months post infusion following a severe infection of COVID-19, while patient 2 maintained remission over 24 months. Relapse was accompanied by reactivation of pathogenic B cells and recurrence of autoantibodies/peptides targeting axons or myelin. Metabolic reprogramming of B cells characterized by overglycolysis was linked to disease relapse, which could be modulated by regulatory factor X5. CONCLUSION:This study demonstrates the safety and potential of anti-BCMA CAR-T cell therapy in treating refractory CIDP and provides insights into the molecular mechanisms underlying patient responses (ClinicalTrials.gov: NCT04561557). FUNDING:Ministry of Science and Technology China Brain Initiative grant STI2030-Major Projects 2022ZD0204700 (to W.W.), National Natural Science Foundation of China grants 82371404 and 82071380 (to D.-S.T.) and 82471353 and 82271341 (to C.Q.), Knowledge Innovation Program of Wuhan Shuguang Project 2022020801020454 (to C.Q.), and Key Research and Development Program of Hubei Provincial Department of Science and Technology 2023BCB148 (to D.-S.T.). The clinical trial was funded by Nanjing IASO Biotechnology Co., Ltd.

Atherosclerosis (AS) has been shown to be an independent risk factor for vascular cognitive impairment (VCI), but the mechanisms remain unclear. Here, we found that AS circulating exosomes exacerbated ischemic white matter injury and VCI. Exosomes originating from macrophage-derived foam cells targeted microglia. Mechanistically, foam cell-derived exosomes transmitted redox imbalance, mitochondrial dysfunction, and metabolic defects to microglia via the miR-101-3p-Nrf2-Slc2a1 axis. Anti-miR-101-3p or activation of Nrf2, both genetically and pharmacologically, could antagonize AS exosomes and ameliorate VCI. In conclusion, our findings reveal a distant connection between peripheral macrophages and brain microglia, which provides new insights and potential targets of AS-induced VCI.

Genetic and environmental factors jointly affect the onset of multiple sclerosis (MS), among which diet holds considerable interest as a potentially modifiable factor. A nested case-control study was conducted, including 303 participants with MS and 1212 age- and sex-matched controls from the UK Biobank. Conditional logistic regression models were used to estimate the relationship between diet and MS. Mendelian randomization (MR) analysis was employed to examine the genetic associations between various food types and the risk of MS. Mediation analyses were performed to determine the possible mediating effect of serum measurements using the Karlson-Holm-Breen method. Participants who regularly consumed oily fish and consumed more bread per week had a decreased risk of MS. Increased consumption of oily fish and cereal was genetically associated with a lower risk of MS. The association between oily fish intake and reduced risk of MS remained robust among several subgroups. Besides, vitamin D and neutrophil count mediated the protective effects of oily fish consumption against MS, independently. Increasing the intake of both oily fish and wholemeal/wholegrain bread may reduce the risk of MS onset, while vitamin D and neutrophil count play a partial mediating role during this process.

Progressive multiple sclerosis (PMS), which is characterized by relentless disease progression, lacks effective treatment. While recent studies have highlighted the importance of B cells in driving compartmentalized central nervous system (CNS) inflammation in PMS pathogenesis, current B cell depletion therapies, such as CD20 monoclonal antibodies, face challenges in targeting plasma cells within the CNS. Here, we treated five patients with PMS (one primary PMS and four secondary PMS) with anti-B cell maturation antigen (BCMA) chimeric antigen receptor T (CAR-T) cell therapy in an ongoing phase 1 clinical trial (ClinicalTrials.gov: NCT04561557). Only grade 1 cytokine release syndrome was observed, and all grade ≥3 cytopenias occurred within 40 days post-infusion in all five patients. Meanwhile, we detected plasma cell depletion in CNS compartments, prolonged expansion and relieved exhaustion of CAR-T cells in the cerebrospinal fluid, and attenuation of microglial activation. These findings provided insights into the potential application of anti-BCMA CAR-T therapy for advancing clinical management of PMS.

To the Editor: Depression is a common psychiatric disorder, affecting over 260 million people of all ages globally.[1] Prior studies investigating the association between antidepressant use and stroke risk have yielded inconsistent results.[2,3] Consequently, it remains unclear which of the various antidepressant categories may affect stroke. Thus, the rational use of antidepressants is important for reducing stroke risk and recurrence, while offering candidate therapeutic targets. Drug-target Mendelian randomization (MR) analysis, which uses genetic variants located in or near the region of drug target genes as proxies for drug effects, is a promising tool for identifying causal links between drug targets and diseases. This study aimed to evaluate the causal associations between antidepressant target genes and stroke and its various subtypes (including any stroke [AS], ischemic stroke [IS], large artery atherosclerosis stroke [LAA], cardioembolic stroke [CES], and small vessel stroke [SVS]) using drug-target MR analysis. Various antidepressants were identified from the World Health Organization Collaborating Centre for Drug Statistics Methodology, and were classified by the Anatomical Therapeutic Chemical classification system. The DrugBank (https://go.drugbank.com/) and ChEMBL (https://www.ebi.ac.uk/chembl/) databases were used to determine the genes encoding the targets of antidepressants. To identify genetic variants as proxies for the effect of drug target genes, blood cis-expression quantitative trait loci (eQTL) data from the eQTLGen Consortium (n = 31,684) were used. The cis-eQTL located within 1 Mb downstream or upstream of the region of the drug target genes with a false discovery rate (FDR) <0.05 and F-statistic (calculated by the formula: F-statistic = beta2/se2) >10 were screened. Independent genetic variants without linkage disequilibrium (r2 <0.1) were used as the instrumental variables (IVs). Genome-wide association studies (GWAS) summary data for stroke and its subtypes were from GIGASTROKE consortium. Our study included only individuals of European ancestry, comprising AS (73,652 cases and 1,234,808 controls), IS (62,100 cases), LAA (6399 cases), CES (10,804 cases), and SVS (6811 cases). All participants enrolled in this study were of European ancestry, with no sample overlap with the exposure dataset in the main analysis. Detailed information of the different data sources is provided in Supplementary Table 1, https://links.lww.com/CM9/C261. All MR analyses were performed using TwoSampleMR R package in R software (v.4.0.3, R Development Core Team, Vienna, Austria), while the inverse variance weighted method was used to estimate the causal effects. The FDR method was applied for multiple testing, with an FDR <0.05 indicating statistical significance. Sensitivity analyses, including heterogeneity and pleiotropy tests, were performed using Cochrane's Q test, Rucker's Q test, MR-Egger intercept test, MR pleiotropy residual sum and outlier global test, and leave-one-out analysis. Colocalization analysis was conducted between the significant drug target genes identified in the primary MR analysis and stroke outcomes. A posterior probability of hypothesis 4 (PPH4) >0.8 was used to characterize significant evidence for colocalization. Further, we assessed the causal relationship between the candidate target genes and cerebrovascular risk factors. For drug target genes causally linked to both stroke and risk factors, a two-step mediation MR analysis was conducted to evaluate the effects of drug target genes (exposure) on stroke (outcomes) via the cerebrovascular risk factors (mediators). To determine whether the observed associations between antidepressant target gene expression and stroke risk are likely mediated by major depressive disorder (MDD) or independent of MDD, MR analysis was also conducted to evaluate the associations between MDD and stroke. Further details of this analysis are provided in the Supplementary Methods, https://links.lww.com/CM9/C261. A flow diagram of the study is presented in Supplementary Figure 1, https://links.lww.com/CM9/C261. A total of 111 drug targets encoding proteins have previously been experimentally shown to be modified by one or more antidepressants. After selecting the IVs for the antidepressant target genes, 29 of the 111 genes were identified in the outcome datasets [Supplementary Tables 2–4, https://links.lww.com/CM9/C261]. The associations between genetically predicted antidepressant target genes and stroke are presented in Figure 1, Supplementary Figures 2 and 3, and Supplementary Tables 5–11, https://links.lww.com/CM9/C261. Following FDR adjustment, we identified five drug target genes significantly associated with AS risk: KCNH2 (odds ratio [OR] = 1.057, 95% confidence interval [CI] 1.017–1.098, FDR = 0.027), MPO (OR = 1.071, 95% CI = 1.050–1.093, FDR = 7.81E−10), SIGMAR1 (OR = 0.952, 95% CI = 0.934–0.971, FDR = 1.12E−05), WARS (OR = 0.982, 95% CI = 0.973–0.992, FDR = 0.003), WARS2 (OR = 0.981, 95% CI = 0.970–0.993, FDR = 0.010). Moreover, four genetically predicted drug target genes were found to be significantly associated with IS risk: MPO (OR = 1.078, 95% CI = 1.052–1.105, FDR = 5.55E−08), SIGMAR1 (OR = 0.946, 95% CI = 0.927–0.965, FDR = 1.05E−06), SLC18A2 (OR = 0.942, 95% CI = 0.902–0.983, FDR = 0.043), WARS (OR = 0.980, 95% CI = 0.970–0.991, FDR = 0.002). Genetically predicted GRIN2D (LAA: OR = 0.465, 95% CI = 0.293–0.739, FDR = 0.034), KCNH2 (CES: OR = 1.222, 95% CI = 1.128–1.325, FDR = 2.95E−05), and WARS2 (SVS: OR = 0.938, 95% CI = 0.905–0.972, FDR = 0.011) levels were also found to be significantly associated with LAA, CES and SVS, respectively. Colocalization analysis indicated that MPO and IS, as well as GRIN2D and LAA, probably shared a causal single nucleotide polymorphism in the gene locus (MPO: PPH4 = 0.884; GRIN2D: PPH4 = 0.824; Supplementary Figure 4 and Supplementary Table 12, https://links.lww.com/CM9/C261).Figure 1: MR analysis of significant drug target genes with stroke risk. Five antidepressant targets (KCNH2, MPO, SIGMAR1, WARS, and WARS2) were significantly associated with AS risk after FDR adjustment. Additionally, four targets (MPO, SIGMAR1, SLC18A2, and WARS) showed significant associations with IS risk. Genetically predicted GRIN2D, KCNH2, and WARS2 were significantly linked to LAA, CES, and SVS, respectively. AS: Any stroke; CES: Cardioembolic stroke; CI: Confidence interval; FDR: False discovery rate; IS: Ischemic stroke; LAA: Large artery atherosclerosis stroke; MR: Mendelian randomization; OR: Odds ratio; SVS: Small-vessel stroke.The associations between MPO and GRIN2D with 14 cerebrovascular risk factors were also investigated [Supplementary Figure 5 and Supplementary Tables 13–15, https://links.lww.com/CM9/C261]. Genetically predicted MPO levels were significantly associated with atrial fibrillation (AF; OR = 1.043, 95% CI = 1.018–1.068, FDR = 0.003), heart failure (HF; OR = 1.048, 95% CI = 1.023–1.075, FDR = 0.002), and systolic blood pressure (SBP; OR = 1.256, 95% CI = 1.104–1.428, FDR = 0.003). MR analysis further revealed the causal effects of genetically predicted GRIN2D on AF (OR = 0.819, 95% CI = 0.732–0.917, FDR = 0.008) and triglyceride levels (OR = 0.829, 95% CI = 0.724–0.948, FDR = 0.045). A two-step mediation MR analysis was applied to evaluate the effects of MPO on stroke outcomes (AS and IS) via risk factors (AF, HF, and SBP). The proportions of the mediation effect of MPO on AS and IS via AF were 9.7% and 9.4%, respectively, while the corresponding values via SBP were 8.5% and 8.0%, respectively. The indirect effect of MPO on the risk of AS and IS via HF accounted for 29.7% and 30.2% of the total effect, respectively [Supplementary Figure 6 and Supplementary Table 16, https://links.lww.com/CM9/C261]. We found no evidence to support an association between genetically estimated MDD and AS, IS, LAA, CES, or SVS (all P values >0.05; stroke GWAS from GIGASTROKE or MEGASTROKE; Supplementary Figure 7 and Supplementary Tables 17 and 18, https://links.lww.com/CM9/C261). This indicates that the observed association of target genes with stroke is unlikely to be solely caused by MDD, and indicates that this association is likely independent of the association with MDD. The present study identified associations between antidepressant targets and stroke and its subtypes through drug-target MR analysis. In addition, we identified two candidate antidepressant target genes for IS and LAA (MPO and GRIN2D, respectively). Myeloperoxidase (MPO), a key inflammatory factor in the myeloid system, is highly expressed in activated human neutrophils, and plays an important role in inflammation and oxidative stress responses. Prior studies have shown that inhibition of MPO activity can reduce inflammation and enhance cellular protection against IS.[4]GRIN2D encodes the glutamate ionotropic receptor N-Methyl-D-Aspartate (NMDA) type subunit 2D (GluN2D), which is a subunit of the NMDA Receptor (NMDAR) and is involved in learning, memory, and synaptic functioning.[5] There is currently limited evidence linking GRIN2D with LAA or atherosclerosis, highlighting the need for further investigation. This study has several strengths. First, this MR study integrated the latest and largest GWAS and eQTL datasets to investigate causality and reduce confounding factors and reverse causation. Second, we systematically examined various antidepressant targets and stroke subtypes, and performed several sensitivity analyses to support our findings. Third, MR analysis of multiple cerebrovascular risk factors was performed to identify potential side effects and alternative indications crucial for future clinical applications. However, this study has several limitations, as follows. First, all participants included in the GWAS used in the present study were of European ancestry; therefore, our findings require validation in other races. Although our MR analysis indicated potential causal relationships, these associations should not be interpreted as direct evidence to indicate that antidepressants targeting these proteins would have causal effects on stroke risk. Inferring the actual pharmacological effects from genetic analyses is associated with complexities owing to variations in drug mechanisms, timing, magnitude, and duration of exposure. Although our colocalization analysis provided strong evidence to support the existence of shared causal variants in MPO and GRIN2D, the lack of colocalization evidence for other genes with MR evidence indicates that these relationships may require further investigation using larger datasets or complementary methods. Further studies are thus required to determine the effects of antidepressants on the risk of stroke. Our findings also require validation using independent datasets to ensure their robustness and broader applicability. Future research should thus explore downstream biomarkers to gain a more comprehensive understanding of the effects of antidepressant targets on stroke risk. As larger protein quantitative trait locus datasets become available, the investigation of drug-target relationships should be enhanced. Moreover, there is the potential for survivor bias because the GWAS primarily recruited survivors, possibly missing the genetic risk profiles of those who did not survive severe strokes. Finally, we identified a robust causal relationship between MPO and HF, with HF mediating the association between MPO and IS risk. Further research in non-HF patients is required to minimize potential pleiotropic effects. In conclusion, our drug target MR analysis provides insights into the associations between antidepressant targets and stroke, guiding the selection of antidepressants for individuals at risk of stroke, and identifying MPO and GRIN2D as promising stroke drug targets. However, further research is required to verify the long-term effects of antidepressants on stroke risk.

BACKGROUND:Circulating insulin-like growth factor 1 (IGF-1) is positively associated with the risks of certain neurological disorders, including stroke, Alzheimer's disease, and Parkinson's disease. However, the association of IGF-1 with the risk of multiple sclerosis (MS) remains unclear. METHODS:A total of 348,324 participants at baseline were included from the UK biobank in this prospective study. The association of circulating IGF-1 level with MS was analyzed by Cox proportional hazard models. Further, subgroup analyses were conducted to investigate the variables influencing these associations. RESULTS:Among 348,324 individuals, lower circulating IGF-1 concentrations were associated with a reduced risk of MS (95 % CI, 0.5930-0.9700; P value = 0.02763). The association between lower IGF-1 levels and reduced risk of MS remains robust in older and female participants. Moreover, risk of MS appeared to be lower in IGF-1-low individuals who never smoked, currently drinking alcohol, with higher body mass index, and higher glucose concentrations. CONCLUSION:Our findings indicate that a lower concentration of serum IGF-1 was associated with a reduced risk of MS. The results provide evidence that the circulating IGF-1 may play a significant role in the pathogenesis of MS.

Cognitive dysfunction poses a significant challenge in clinical practice, but currently available drugs mainly address symptoms and have limited effectiveness in treating cognitive dysfunction associated with various neurological disorders. Mendelian randomization (MR) and colocalization analyses were conducted to explore the causal associations between 4302 druggable genes with blood and brain cis-expression quantitative trait loci (eQTLs) and cognitive performance. The causal effects of candidate druggable genes on brain structure and neurological diseases were assessed to gain insights into the underlying mechanisms. Among over 4000 druggable genes, our study identified causal associations between 72 druggable genes (41 blood eQTLs and 31 brain eQTLs) and cognitive performance. Thirteen eQTLs (six in blood: ERBB3, SPEG, ATP2A1, GDF11, CYP2D6, GANAB; seven in brain: ERBB3, DPYD, TAB1, WNT4, CLCN2, PPM1B, CAMKV) were identified as candidate druggable genes for cognitive performance. Notably, both blood and brain eQTLs of ERBB3 were negatively associated with cognitive performance (blood: OR = 0.933, 95% CI 0.911-0.956, p-value = 9.69E-09; brain: OR = 0.782, 95% CI 0.718-0.852, p-value = 2.13E-08). Moreover, these candidate druggable genes exhibited causal effects on both brain structure and neurological diseases. Our integrative analysis provides genetic evidence supporting candidate therapeutic targets for improving cognitive performance and treating neurological diseases. Furthermore, it sheds light on the possible mechanisms by which these targets affect brain structures. This finding suggested that these identified druggable genes, particularly ERBB3 and CYP2D6, hold promise as potential drug targets for enhancing cognitive performance.

The causal relationship between gut microbiota (GM) and white matter injury and communication remains unclear. We aimed to scrutinize the plausible causal impact of GM on white matter hyperintensities (WMHs), white matter microstructure, white matter connectivity, and multiple neurological diseases via Mendelian randomization study. We identified four WMH-related bacterial taxa, including class Melainabacteria, order Gastranaerophilales, family Alcaligenaceae, and genus Ruminiclostridium 6 In addition, three bacterial taxa were discovered that have consistent effect on multiple aspects of white matter microstructure. Furthermore, we found 12 strong associations between genetic liability in GM and white matter connectivity. Among these bacterial taxa, the family Clostridiaceae 1 demonstrated a protective effect against ischemic stroke (IS). The genus Barnesiella showed protective effect on IS and small vessel stroke while posed a risk effect on neuromyelitis optica spectrum disorder (NMOSD), as well as on aquaporin-4 immunoglobulin G-positive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD). The order Desulfovibrionales and family Desulfovibrionaceae showed protective effect against cardioembolic stroke, and the genus Ruminococcus gnavus group showed a protective effect on amyotrophic lateral sclerosis. In terms of the mapped genes of statistically significant bacterial taxa, genes such as CPNE1, PIGU, MED22, SURF6, DOCK10, and COPS3 exhibited a significant causal correlation with the corresponding white matter connectivity. This study demonstrated a genetically predicted causal relationship between GM and WMH, white matter microstructure, white matter connectivity, and multiple neurological diseases, based on GWAS data from mixed-sex cohorts without sex-stratified summary statistics. These findings highlight the potential role of GM in influencing brain structural integrity.

Background Stroke is a leading cause of death worldwide, with a lack of effective treatments for improving the prognosis. The aim of the present study was to identify novel therapeutic targets for functional outcome after ischemic stroke . Methods and Results Cis‐expression quantitative trait loci data for druggable genes were used as instrumental variables. The primary outcome was the modified Rankin Scale score at 3 months after ischemic stroke, evaluated as a dichotomous variable (3–6 versus 0–2) and also as an ordinal variable. Drug target Mendelian randomization, Steiger filtering analysis, and colocalization analysis were performed. Additionally, phenome‐wide Mendelian randomization analysis was performed to identify the safety of the drug target genes at the genetic level. Among >2600 druggable genes, genetically predicted expression of 16 genes ( ABCC2 , ATRAID , BLK , CD93 , CHST13 , NR1H3 , NRBP1 , PI3 , RIPK4 , SEMG1 , SLC22A4 , SLC22A5 , SLCO3A1 , TEK , TLR4 , and WNT10B ) demonstrated the causal associations with ordinal modified Rankin Scale ( P <1.892×10 −5 ) or poor functional outcome (modified Rankin Scale 3–6 versus 0–2, P <1.893×10 −5 ). Steiger filtering analysis suggested potential directional stability ( P <0.05). Colocalization analysis provided further support for the associations between genetically predicted expression of ABCC2 , NRBP1 , PI3 , and SEMG1 with functional outcome after ischemic stroke. Furthermore, phenome‐wide Mendelian randomization revealed additional beneficial indications and few potential safety concerns of therapeutics targeting ABCC2 , NRBP1 , PI3 , and SEMG1 , but the robustness of these results was limited by low power. Conclusions The present study revealed 4 candidate therapeutic targets for improving functional outcome after ischemic stroke, while the underlying mechanisms need further investigation.

Background Oxidative stress and microglial activation are critical pathomechanisms in ischemic white matter injury. Microglia, as resident immune cells in the brain, are the main cells undergoing oxidative stress response. However, the role and molecular mechanism of oxidative stress in microglia have not been clearly elucidated during white matter ischemia. Methods Extensive histological analysis of the corpus callosum was performed in BCAS mice at different time points to assess white matter injury, oxidative stress and microglial activation. Flow cytometric sorting and transcriptomic sequencing were combined to explore the underlying mechanisms regulating microglial oxidative stress and functional phenotypes. The expression of critical molecule in microglia was regulated using Cx3cr1CreER mice and clinical-stage drugs to assess its effect on white matter injury and cognitive function. Results Our study identified nuclear factor erythroid-2 related factor 2 (Nrf2) as a key transcription factor regulating oxidative stress and functional phenotype in microglia. Interestingly, we found that the sustained decrease in transiently upregulated expression of Nrf2 following chronic cerebral hypoperfusion resulted in abnormal microglial activation and white matter injury. In addition, high loads of myelin debris promoted lipid peroxidation and ferroptosis in microglia with diminished antioxidant function. Microglia with pharmacologically or genetically stimulated Nrf2 expression exhibited enhanced resistance to ferroptosis and pro-regenerative properties to myelination due to lipid and iron metabolism reprogramming. Conclusion Weakened Nrf2-mediated antioxidant responses in microglia induced metabolic disturbances and ferroptosis during chronic cerebral hypoperfusion. Targeted enhancement of Nrf2 expression in microglia may be a potential therapeutic strategy for ischemic white matter injury.

Large artery atherosclerosis (LAA) is a prevalent cause of acute ischemic stroke (AIS). Understanding the mechanisms linking atherosclerosis to stroke is essential for developing appropriate intervention strategies. Here, we found that the exosomal miRNA Novel-3 is selectively upregulated in the plasma of patients with LAA-AIS. Notably, Novel-3 was predominantly expressed in macrophage-derived foam cells, and its expression correlated with atherosclerotic plaque vulnerability in patients undergoing carotid endarterectomy. Exploring the function of Novel-3 in a mouse model of cerebral ischemia, we found that Novel-3 exacerbated ischemic injury and targeted microglia and macrophages expressing ionized calcium-binding adapter molecule 1 in peri-infarct regions. Mechanistically, Novel-3 increased ferroptosis and neuroinflammation by interacting with striatin (STRN) and downregulating the phosphoinositide 3-kinase-AKT-mechanistic target of rapamycin signaling pathway. Blocking Novel-3 activity or overexpressing STRN provided neuroprotection under ischemic conditions. Our findings suggest that exosomal Novel-3, which is primarily derived from macrophage-derived foam cells, targets microglia and macrophages in the brain to induce neuroinflammation and could serve as a potential therapeutic target for patients with stroke who have atherosclerosis.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory demyelinating disease of the central nervous system (CNS) accompanied by blood-brain barrier (BBB) disruption. Dysfunction in microglial lipid metabolism is believed to be closely associated with the neuropathology of NMOSD. However, there is limited evidence on the functional relevance of circulating lipids in CNS demyelination, cellular metabolism, and microglial function. Here, we found that serum low-density lipoprotein (LDL) was positively correlated with markers of neurological damage in NMOSD patients. In addition, we demonstrated in a mouse model of NMOSD that LDL penetrates the CNS through the leaky BBB, directly activating microglia. This activation leads to excessive phagocytosis of myelin debris, inhibition of lipid metabolism, and increased glycolysis, ultimately exacerbating myelin damage. We also found that therapeutic interventions aimed at reducing circulating LDL effectively reversed the lipid metabolic dysfunction in microglia and mitigated the demyelinating injury in NMOSD. These findings shed light on the molecular and cellular mechanisms underlying the positive correlation between serum LDL and neurological damage, highlighting the potential therapeutic target for lowering circulating lipids to alleviate the acute demyelinating injury in NMOSD.

Microglia-mediated neuroinflammation contributes to acute demyelination in neuromyelitis optica spectrum disorders (NMOSD). Soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in the CSF has been associated with microglial activation in several neurodegenerative diseases. However, the basis for this immune-mediated attack and the pathophysiological role of sTREM2 in NMOSD remain to be elucidated. Here, we performed Mendelian randomization analysis and identified a genetic association between increased CSF sTREM2 and NMOSD risk. CSF sTREM2 was elevated in patients with NMOSD and was positively correlated with neural injury and other neuroinflammation markers. Single-cell RNA sequencing of human macrophage/microglia-like cells in CSF, a proxy for microglia, showed that increased CSF sTREM2 was positively associated with microglial dysfunction in patients with NMOSD. Furthermore, we demonstrated that sTREM2 is a reliable biomarker of microglial activation in a mouse model of NMOSD. Using unbiased transcriptomic and lipidomic screens, we identified that excessive activation, overwhelmed phagocytosis of myelin debris, suppressed lipid metabolism and enhanced glycolysis underlie sTREM2-mediated microglial dysfunction, possibly through the nuclear factor kappa B (NF-κB) signalling pathway. These molecular and cellular findings provide a mechanistic explanation for the genetic association between CSF sTREM2 and NMOSD risk and indicate that sTREM2 could be a potential biomarker of NMOSD progression and a therapeutic target for microglia-mediated neuroinflammation.

Chimeric antigen receptor (CAR)-T cell therapy has achieved remarkable success in the treatment of hematological malignancies. Based on the immunomodulatory capability of CAR-T cells, efforts have turned toward exploring their potential in treating autoimmune diseases. Bibliometric analysis of 210 records from 128 academic journals published by 372 institutions in 40 countries/regions indicates a growing number of publications on CAR-T therapy for autoimmune diseases, covering a range of subtypes such as systemic lupus erythematosus, multiple sclerosis, among others. CAR-T therapy holds promise in mitigating several shortcomings, including the indiscriminate suppression of the immune system by traditional immunosuppressants, and non-sustaining therapeutic levels of monoclonal antibodies due to inherent pharmacokinetic constraints. By persisting and proliferating in vivo, CAR-T cells can offer a tailored and precise therapeutics. This paper reviewed preclinical experiments and clinical trials involving CAR-T and CAR-related therapies in various autoimmune diseases, incorporating innovations well-studied in the field of hematological tumors, aiming to explore a safe and effective therapeutic option for relapsed/refractory autoimmune diseases.

Chronic cerebral hypoperfusion (CCH), a disease afflicting numerous individuals worldwide, is a primary cause of cognitive deficits, the pathogenesis of which remains poorly understood. Bruton's tyrosine kinase inhibition (BTKi) is considered a promising strategy to regulate inflammatory responses within the brain, a crucial process that is assumed to drive ischemic demyelination progression. However, the potential role of BTKi in CCH has not been investigated so far. In the present study, we elucidated potential therapeutic roles of BTK in both in vitro hypoxia and in vivo ischemic demyelination model. We found that cerebral hypoperfusion induced white matter injury, cognitive impairments, microglial BTK activation, along with a series of microglia responses associated with inflammation, oxidative stress, mitochondrial dysfunction, and ferroptosis. Tolebrutinib treatment suppressed both the activation of microglia and microglial BTK expression. Meanwhile, microglia-related inflammation and ferroptosis processes were attenuated evidently, contributing to lower levels of disease severity. Taken together, BTKi ameliorated white matter injury and cognitive impairments induced by CCH, possibly via skewing microglia polarization towards anti-inflammatory and homeostatic phenotypes, as well as decreasing microglial oxidative stress damage and ferroptosis, which exhibits promising therapeutic potential in chronic cerebral hypoperfusion-induced demyelination.