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BACKGROUND: Congenital heart disease (CHD) is a group of complex heart defects associated with hematologic abnormalities, including increased risk of thrombotic and bleeding events. Past studies have observed evidence of platelet hyperreactivity, while other studies showed decreased platelet activation in patients with CHD. The goal of this study was to develop a mass spectrometry approach to characterize single platelets in infants with CHD and identify potential etiology for such discrepant results. METHODS: We enrolled 19 infants with CHD along with 21 non-CHD controls at Yale New Haven Children's Heart Center. A single-cell high-dimensional mass cytometry method was developed to quantitatively interrogate platelet surface markers in whole blood. Additionally, plasma cytokine analysis was performed through a multiplexed panel of 52 vascular and inflammatory markers to assess for platelet releasates. RESULTS: We found that infants with CHD had significant differences in platelet activation and functional markers by mass cytometry compared with non-CHD controls. Based on cell surface markers, we classified the platelets into 8 subpopulations (P0 to P7). Distinct subpopulations of platelets (P1, P4, and P5) exhibiting decreased aggregatory phenotype but altered secretory phenotypes were also identified and found to be more abundant in the blood of infants with CHD. Electron microscopy identified increased proportion of hypogranular platelets in CHD. Moreover, cytokine analysis demonstrated an overall increase in plasma cytokines and biomarkers in CHD, including IL (interleukin)-6, IL-8, IL-27, RANTES, and VWF (von Willebrand factor), which are expressed in platelet granules and can be released upon activation. CONCLUSIONS: We developed a robust mass cytometry approach to identify platelet phenotypic heterogeneity. Infants with CHD had alterations in distinct subpopulations of platelets with overall reduced aggregatory phenotype and secretory dysfunction. These findings suggest that platelets in infants with CHD may be exhausted due to persistent stimulation and may explain both bleeding and thrombotic vascular complications associated with CHD.
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Redox biology is fundamental to both normal cellular homeostasis and pathological states associated with excessive oxidative stress. Reactive oxygen species function not only as signaling molecules but also as redox regulators of protein function. In the vascular system, redox reactions help regulate key physiologic responses such as cell adhesion, vasoconstriction, platelet aggregation, angiogenesis, inflammatory gene expression, and apoptosis. During pathologic states, altered redox balance can cause vascular cell dysfunction and affect the equilibrium between procoagulant and anticoagulant systems, contributing to thrombotic vascular disease. This review focuses on the emerging role of a specific reversible redox reaction, protein methionine oxidation, in vascular disease and thrombosis. A growing number of cardiovascular and hemostatic proteins are recognized to undergo reversible methionine oxidation, in which methionine residues are posttranslationally oxidized to methionine sulfoxide. Protein methionine oxidation can be reversed by the action of stereospecific enzymes known as methionine sulfoxide reductases. Calcium/calmodulin-dependent protein kinase II is a prototypical methionine redox sensor that responds to changes in the intracellular redox state via reversible oxidation of tandem methionine residues in its regulatory domain. Several other proteins with oxidation-sensitive methionine residues, including apolipoprotein A-I, thrombomodulin, and von Willebrand factor, may contribute to vascular disease and thrombosis.
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Metionina/metabolismo , Oxirredução , Estresse Oxidativo/fisiologia , Proteínas/metabolismo , Trombose/metabolismo , Animais , Humanos , Espécies Reativas de Oxigênio/metabolismo , Doenças Vasculares/metabolismoRESUMO
OBJECTIVE: Clinical evidence suggests an association between oxidative stress and vascular disease, and in vitro studies have demonstrated that reactive oxygen species can have prothrombotic effects on vascular and blood cells. It remains unclear, however, whether elevated levels of reactive oxygen species accelerate susceptibility to experimental thrombosis in vivo. APPROACH AND RESULTS: Using a murine model with genetic deficiency in superoxide dismutase-1 (SOD1), we measured susceptibility to carotid artery thrombosis in response to photochemical injury. We found that SOD1-deficient (Sod1(-/-)) mice formed stable arterial occlusions significantly faster than wild-type (Sod1(+/+)) mice (P<0.05). Sod1(-/-) mice also developed significantly larger venous thrombi than Sod1(+/+) mice after inferior vena cava ligation (P<0.05). Activation of protein C by thrombin in lung was diminished in Sod1(-/-) mice (P<0.05 versus Sod1(+/+) mice), and generation of activated protein C in response to infusion of thrombin in vivo was decreased in Sod1(-/-) mice (P<0.05 versus Sod1(+/+) mice). SOD1 deficiency had no effect on the expression of thrombomodulin, endothelial protein C receptor, or tissue factor in lung or levels of protein C in plasma. Exposure of human thrombomodulin to superoxide in vitro caused oxidation of multiple methionine residues, including critical methionine 388, and a 40% decrease in thrombomodulin-dependent activation of protein C (P<0.05). SOD and catalase protected against superoxide-induced methionine oxidation and restored protein C activation in vitro (P<0.05). CONCLUSIONS: SOD prevents thrombomodulin methionine oxidation, promotes protein C activation, and protects against arterial and venous thrombosis in mice.
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Lesões das Artérias Carótidas/enzimologia , Proteína C/metabolismo , Superóxido Dismutase/deficiência , Trombose/enzimologia , Trombose Venosa/enzimologia , Animais , Lesões das Artérias Carótidas/genética , Lesões das Artérias Carótidas/patologia , Artéria Carótida Primitiva/enzimologia , Artéria Carótida Primitiva/patologia , Catalase/metabolismo , Modelos Animais de Doenças , Ativação Enzimática , Humanos , Camundongos da Linhagem 129 , Camundongos Transgênicos , Oxirredução , Estresse Oxidativo , Superóxido Dismutase/genética , Superóxido Dismutase-1 , Superóxidos/metabolismo , Trombomodulina/metabolismo , Trombose/genética , Trombose/patologia , Veia Cava Inferior/enzimologia , Veia Cava Inferior/patologia , Trombose Venosa/patologiaRESUMO
OBJECTIVE: Emerging evidence suggests that methionine oxidation can directly affect protein function and may be linked to cardiovascular disease. The objective of this study was to define the role of the methionine sulfoxide reductase A (MsrA) in models of vascular disease and identify its signaling pathways. APPROACH AND RESULTS: MsrA was readily identified in all layers of the vascular wall in human and murine arteries. Deletion of the MsrA gene did not affect atherosclerotic lesion area in apolipoprotein E-deficient mice and had no significant effect on susceptibility to experimental thrombosis after photochemical injury. In contrast, the neointimal area after vascular injury caused by complete ligation of the common carotid artery was significantly greater in MsrA-deficient than in control mice. In aortic vascular smooth muscle cells lacking MsrA, cell proliferation was significantly increased because of accelerated G1/S transition. In parallel, cyclin D1 protein and cdk4/cyclin D1 complex formation and activity were increased in MsrA-deficient vascular smooth muscle cell, leading to enhanced retinoblastoma protein phosphorylation and transcription of E2F. Finally, MsrA-deficient vascular smooth muscle cell exhibited greater activation of extracellular signal-regulated kinase 1/2 that was caused by increased activity of the Ras/Raf/mitogen-activated protein kinase signaling pathway. CONCLUSIONS: Our findings implicate MsrA as a negative regulator of vascular smooth muscle cell proliferation and neointimal hyperplasia after vascular injury through control of the Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 signaling pathway.
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Doenças da Aorta/enzimologia , Aterosclerose/enzimologia , Lesões das Artérias Carótidas/enzimologia , Deleção de Genes , Metionina Sulfóxido Redutases/deficiência , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Neointima , Transdução de Sinais , Trombose/enzimologia , Animais , Aorta/enzimologia , Aorta/patologia , Doenças da Aorta/genética , Doenças da Aorta/patologia , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Aterosclerose/genética , Aterosclerose/patologia , Artérias Carótidas/enzimologia , Artérias Carótidas/patologia , Lesões das Artérias Carótidas/genética , Lesões das Artérias Carótidas/patologia , Ciclo Celular , Proteínas de Ciclo Celular/metabolismo , Movimento Celular , Proliferação de Células , Células Cultivadas , Modelos Animais de Doenças , Feminino , Humanos , Hiperplasia , Masculino , Metionina Sulfóxido Redutases/genética , Camundongos Endogâmicos C57BL , Camundongos Knockout , Miócitos de Músculo Liso/enzimologia , Miócitos de Músculo Liso/patologia , Trombose/sangue , Trombose/genética , Fatores de Tempo , Quinases raf/metabolismo , Proteínas ras/metabolismoRESUMO
In this issue of Cell Stem Cell, Kawakami et al. develop a SARS-CoV-2 infection-competent, progenitor-derived, human vascular organoid model and uncover a role for complement factor D (CFD) in mediating microvascular immunothrombosis. This model may be applied to conditions where microvascular disease plays a major pathogenic role.
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COVID-19 , Humanos , OrganoidesRESUMO
Structural determination of the ABCC4 transporter is a major first step in providing crucial molecular insights into the transport of platelet substrates into granules, as well as drug transport from platelets. The findings provide a framework for understanding platelet interactions and potential design of specific platelet antagonists.
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OBJECTIVES: Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is historically associated with Helicobacter pylori (HP) infections in more than 80% of patients. However, the incidence of HP-negative MALT lymphoma has been increasing. The clinicopathologic features have not been well studied, and optimal management strategies remain unclear. METHODS: The pathology database was searched for primary gastric MALT lymphomas diagnosed from 2000 to 2017. The clinical data and the slides were reviewed. The cases were divided for analysis into those with a background of chronic gastritis with HP, chronic gastritis without HP, and without either a background of chronic gastritis or HP. RESULTS: Of 70 gastric MALT lymphoma cases identified, 26 (37% of total) had chronic gastritis and were positive for HP histologically (n = 23) or were HP positive by additional laboratory testing (n = 3). The remaining 44 (63% of total) cases were HP negative by histology. Within the HP-negative cases, 5 (11% of HP-negative cases) showed histologic gastritis while 39 (89% of HP-negative cases) did not have sufficient evidence of gastritis through review of slides (n = 18) or based on available pathology reports (n = 21). The HP-negative cases without gastritis had higher propensities to show a mass lesion on endoscopy compared with HP-positive cases (37.5% vs 11.1%, P = .02) at the initial diagnosis. The immunophenotype and rate of positive B-cell gene rearrangement were not significantly different between the 2 groups. While all HP-positive patients received antibiotics for HP eradication, treatment in the HP-negative group varied among antibiotics, radiation, rituximab, or chemotherapy. Among HP-negative patients with available follow-up, 13 (39%) showed disease recurrence, similar to the recurrence rate in HP-positive patients; however, no individual from either group has died of the disease thus far. CONCLUSIONS: The incidence of HP-negative MALT lymphoma is increasing, and in our practice, it is currently more common than HP-associated MALT lymphomas. The pathophysiology of HP-negative MALT lymphoma without chronic gastritis remains unclear. Follow-up data in our study suggest that the prognosis of these cases is excellent despite varied management modalities.
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Gastrite Atrófica , Gastrite , Infecções por Helicobacter , Helicobacter pylori , Linfoma de Zona Marginal Tipo Células B , Neoplasias Gástricas , Humanos , Linfoma de Zona Marginal Tipo Células B/patologia , Helicobacter pylori/fisiologia , Recidiva Local de Neoplasia , Infecções por Helicobacter/diagnóstico , Neoplasias Gástricas/patologia , Gastrite/patologia , Antibacterianos/uso terapêutico , Tecido Linfoide/patologia , Mucosa/patologiaRESUMO
Aging is intrinsically linked with physiologic decline and is a major risk factor for a broad range of diseases. The deleterious effects of advancing age on the vascular system are evidenced by the high incidence and prevalence of cardiovascular disease in the elderly. Reactive oxygen species are critical mediators of normal vascular physiology and have been shown to gradually increase in the vasculature with age. There is a growing appreciation for the complexity of oxidant and antioxidant systems at the cellular and molecular levels, and accumulating evidence indicates a causal association between oxidative stress and age-related vascular disease. Herein, we review the current understanding of mechanistic links between oxidative stress and thrombotic vascular disease and the changes that occur with aging. While several vascular cells are key contributors, we focus on oxidative changes that occur in platelets and their mediation in disease progression. Additionally, we discuss the impact of comorbid conditions (i.e., diabetes, atherosclerosis, obesity, cancer, etc.) that have been associated with platelet redox dysregulation and vascular disease pathogenesis. As we continue to unravel the fundamental redox mechanisms of the vascular system, we will be able to develop more targeted therapeutic strategies for the prevention and management of age-associated vascular disease.
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Platelets have been shown to be associated with pathophysiological process beyond thrombosis, demonstrating critical additional roles in homeostatic processes, such as immune regulation, and vascular remodeling. Platelets themselves can have multiple functional states and can communicate and regulate other cells including immune cells and vascular smooth muscle cells, to serve such diverse functions. Although traditional platelet functional assays are informative and reliable, they are limited in their ability to unravel platelet phenotypic heterogeneity and interactions. Developments in methods such as electron microscopy, flow cytometry, mass spectrometry, and 'omics' studies, have led to new insights. In this Review, we focus on advances in platelet biology and function, with an emphasis on current and promising methodologies. We also discuss technical and biological challenges in platelet investigations. Using coronavirus disease 2019 (COVID-19) as an example, we further describe the translational relevance of these approaches and the possible 'bench-to-bedside' utility in patient diagnosis and care.
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Helicobacter pylori's unique ability to colonize and survive in the acidic environment of the stomach is critically dependent on uptake of urea through the urea channel, HpUreI. Hence, HpUreI may represent a promising target for the development of specific drugs against this human pathogen. To obtain insight into the structure-function relationship of this channel, we developed conditions for the high-yield expression and purification of stable recombinant HpUreI. Detergent-solubilized HpUreI forms a homotrimer, as determined by chemical cross-linking. Urea dissociation kinetics of purified HpUreI were determined by means of the scintillation proximity assay, whereas urea efflux was measured in HpUreI-containing proteoliposomes using stopped-flow spectrometry to determine the kinetics and selectivity of the urea channel. The kinetic analyses revealed that urea conduction in HpUreI is pH-sensitive and saturable with a half-saturation concentration (or K(0.5)) of ~163 mM. The extent of binding of urea by HpUreI was increased at lower pH; however, the apparent affinity of urea binding (~150 mM) was not significantly pH-dependent. The solute selectivity analysis indicated that HpUreI is highly selective for urea and hydroxyurea. Removing either amino group of urea molecules diminishes their permeability through HpUreI. Similar to urea conduction, diffusion of water through HpUreI is pH-dependent with low water permeability at neutral pH.
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Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Helicobacter pylori/metabolismo , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/metabolismo , Ureia/metabolismo , Proteínas de Bactérias/genética , Transporte Biológico , Helicobacter pylori/química , Helicobacter pylori/genética , Concentração de Íons de Hidrogênio , Cinética , Proteínas de Membrana Transportadoras/genética , Ligação Proteica , Especificidade por Substrato , Ureia/químicaRESUMO
This case illustrates a rare and aggressive entity in AIDS-related lymphoproliferative disorders and highlights the importance and challenges of recognizing PEL outside of cavitary lesions.
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The core pathology of coronavirus disease 2019 (COVID-19) is infection of airway cells by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that results in excessive inflammation and respiratory disease, with cytokine storm and acute respiratory distress syndrome implicated in the most severe cases. Thrombotic complications are a major cause of morbidity and mortality in patients with COVID-19. Patients with pre-existing cardiovascular disease and/or traditional cardiovascular risk factors, including obesity, diabetes mellitus, hypertension and advanced age, are at the highest risk of death from COVID-19. In this Review, we summarize new lines of evidence that point to both platelet and endothelial dysfunction as essential components of COVID-19 pathology and describe the mechanisms that might account for the contribution of cardiovascular risk factors to the most severe outcomes in COVID-19. We highlight the distinct contributions of coagulopathy, thrombocytopathy and endotheliopathy to the pathogenesis of COVID-19 and discuss potential therapeutic strategies in the management of patients with COVD-19. Harnessing the expertise of the biomedical and clinical communities is imperative to expand the available therapeutics beyond anticoagulants and to target both thrombocytopathy and endotheliopathy. Only with such collaborative efforts can we better prepare for further waves and for future coronavirus-related pandemics.
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Transtornos da Coagulação Sanguínea/sangue , Transtornos Plaquetários/sangue , COVID-19/sangue , Endotélio Vascular/fisiopatologia , Inflamação/sangue , Trombose/sangue , Administração por Inalação , Anticoagulantes/uso terapêutico , Transtornos da Coagulação Sanguínea/tratamento farmacológico , Transtornos da Coagulação Sanguínea/etiologia , Transtornos da Coagulação Sanguínea/fisiopatologia , Transtornos Plaquetários/tratamento farmacológico , Transtornos Plaquetários/etiologia , Transtornos Plaquetários/fisiopatologia , COVID-19/complicações , COVID-19/fisiopatologia , Fatores Relaxantes Dependentes do Endotélio/uso terapêutico , Epoprostenol/uso terapêutico , Fatores de Risco de Doenças Cardíacas , Humanos , Iloprosta/uso terapêutico , Inflamação/etiologia , Inflamação/fisiopatologia , Óxido Nítrico/uso terapêutico , Inibidores da Agregação Plaquetária/uso terapêutico , SARS-CoV-2 , Síndrome de Resposta Inflamatória Sistêmica/sangue , Síndrome de Resposta Inflamatória Sistêmica/tratamento farmacológico , Síndrome de Resposta Inflamatória Sistêmica/fisiopatologia , Trombose/etiologia , Trombose/imunologia , Microangiopatias Trombóticas/sangue , Microangiopatias Trombóticas/tratamento farmacológico , Microangiopatias Trombóticas/etiologia , Microangiopatias Trombóticas/fisiopatologia , Doenças Vasculares/sangue , Doenças Vasculares/tratamento farmacológico , Doenças Vasculares/etiologia , Doenças Vasculares/fisiopatologia , Vasodilatadores/uso terapêutico , Tromboembolia Venosa/sangue , Tromboembolia Venosa/tratamento farmacológico , Tromboembolia Venosa/etiologia , Tromboembolia Venosa/fisiopatologia , Tratamento Farmacológico da COVID-19RESUMO
Background Hyperhomocysteinemia is a risk factor for ischemic stroke; however, a targeted treatment strategy is lacking partly because of limited understanding of the causal role of homocysteine in cerebrovascular pathogenesis. Methods and Results In a genetic model of cystathionine beta synthase (CBS) deficiency, we tested the hypothesis that elevation in plasma total homocysteine exacerbates cerebrovascular injury and that memantine, a N-methyl-D-aspartate receptor antagonist, is protective. Mild or severe elevation in plasma total homocysteine was observed in Cbs+/- (6.1±0.3 µmol/L) or Cbs-/- (309±18 µmol/L) mice versus Cbs+/+ (3.1±0.6 µmol/L) mice. Surprisingly, Cbs-/- and Cbs+/- mice exhibited similar increases in cerebral infarct size following middle cerebral artery ischemia/reperfusion injury, despite the much higher total homocysteine levels in Cbs-/- mice. Likewise, disruption of the blood brain barrier was observed in both Cbs+/- and Cbs-/- mice. Administration of the N-methyl-D-aspartate receptor antagonist memantine protected Cbs+/- but not Cbs-/- mice from cerebral infarction and blood brain barrier disruption. Our data suggest that the differential effect of memantine in Cbs+/- versus Cbs-/- mice may be related to changes in expression of N-methyl-D-aspartate receptor subunits. Cbs-/-, but not Cbs+/- mice had increased expression of NR2B subunit, which is known to be relatively insensitive to homocysteine. Conclusions These data provide experimental evidence that even a mild increase in plasma total homocysteine can exacerbate cerebrovascular injury and suggest that N-methyl-D-aspartate receptor antagonism may represent a strategy to prevent reperfusion injury after acute ischemic stroke in patients with mild hyperhomocysteinemia.
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Barreira Hematoencefálica/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Homocisteína/sangue , Hiper-Homocisteinemia/tratamento farmacológico , Infarto da Artéria Cerebral Média/prevenção & controle , Memantina/farmacologia , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Animais , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/patologia , Morte Celular/efeitos dos fármacos , Células Cultivadas , Cistationina beta-Sintase/deficiência , Cistationina beta-Sintase/genética , Modelos Animais de Doenças , Progressão da Doença , Homocistinúria/enzimologia , Homocistinúria/genética , Hiper-Homocisteinemia/sangue , Hiper-Homocisteinemia/enzimologia , Hiper-Homocisteinemia/genética , Infarto da Artéria Cerebral Média/metabolismo , Infarto da Artéria Cerebral Média/patologia , Camundongos Knockout , Neurônios/metabolismo , Neurônios/patologia , Receptores de N-Metil-D-Aspartato/metabolismo , Índice de Gravidade de DoençaRESUMO
The hemostatic response to vascular injury culminates in a fibrin clot network that forms an initial barrier to blood loss and also contributes to microbial host defense. Fibrinogen is cleaved by thrombin into fibrin monomers that spontaneously polymerize into protofibrils and form the extensive fiber networks characteristic of blood clots. In this issue of the JCI, Macrae and colleagues characterize an alternative fibrin structure in which fibrinogen and fibrin assemble into a continuous 2D film at the exterior face of the fibrin clot network. Fibrin films connect to the underlying fiber network through tethering fibers and provide a protective barrier to microbial infiltration. These findings shed new light on a previously overlooked mechanism of fibrin assembly at the clot surface and provide a link between hemostasis and innate immunity.
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Hemostáticos , Trombose , Biofilmes , Fibrina , Fibrinogênio , Hemostasia , Humanos , TrombinaRESUMO
Genetics play a significant role in venous thromboembolism (VTE), yet current clinical laboratory-based testing identifies a known heritable thrombophilia (factor V Leiden, prothrombin gene mutation G20210A, or a deficiency of protein C, protein S, or antithrombin) in only a minority of VTE patients. We hypothesized that a substantial number of VTE patients could have lesser-known thrombophilia mutations. To test this hypothesis, we performed whole-exome sequencing (WES) in 64 patients with VTE, focusing our analysis on a novel 55-gene extended thrombophilia panel that we compiled. Our extended thrombophilia panel identified a probable disease-causing genetic variant or variant of unknown significance in 39 of 64 study patients (60.9%), compared with 6 of 237 control patients without VTE (2.5%) (P < .0001). Clinical laboratory-based thrombophilia testing identified a heritable thrombophilia in only 14 of 54 study patients (25.9%). The majority of WES variants were either associated with thrombosis based on prior reports in the literature or predicted to affect protein structure based on protein modeling performed as part of this study. Variants were found in major thrombophilia genes, various SERPIN genes, and highly conserved areas of other genes with established or potential roles in coagulation or fibrinolysis. Ten patients (15.6%) had >1 variant. Sanger sequencing performed in family members of 4 study patients with and without VTE showed generally concordant results with thrombotic history. WES and extended thrombophilia testing are promising tools for improving our understanding of VTE pathogenesis and identifying inherited thrombophilias.
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Reperfusion injury can exacerbate tissue damage in ischemic stroke, but little is known about the mechanisms linking ROS to stroke severity. Here, we tested the hypothesis that protein methionine oxidation potentiates NF-κB activation and contributes to cerebral ischemia/reperfusion injury. We found that overexpression of methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that reverses protein methionine oxidation, attenuated ROS-augmented NF-κB activation in endothelial cells, in part, by protecting against the oxidation of methionine residues in the regulatory domain of calcium/calmodulin-dependent protein kinase II (CaMKII). In a murine model, MsrA deficiency resulted in increased NF-κB activation and neutrophil infiltration, larger infarct volumes, and more severe neurological impairment after transient cerebral ischemia/reperfusion injury. This phenotype was prevented by inhibition of NF-κB or CaMKII. MsrA-deficient mice also exhibited enhanced leukocyte rolling and upregulation of E-selectin, an endothelial NF-κB-dependent adhesion molecule known to contribute to neurovascular inflammation in ischemic stroke. Finally, bone marrow transplantation experiments demonstrated that the neuroprotective effect was mediated by MsrA expressed in nonhematopoietic cells. These findings suggest that protein methionine oxidation in nonmyeloid cells is a key mechanism of postischemic oxidative injury mediated by NF-κB activation, leading to neutrophil recruitment and neurovascular inflammation in acute ischemic stroke.