Neuroimaging patterns of ischemic stroke after percutaneous coronary intervention.

OBJECTIVES: We sought to determine neuroimaging patterns, ischemic mechanisms, and functional outcomes of ischemic stroke related to percutaneous coronary intervention (PCI) over a 16-year period. BACKGROUND: Stroke is a feared complication of PCI, associated with poor patient outcomes. The majority of strokes that occur after PCI are ischemic rather than hemorrhagic. However, mechanisms of cerebral ischemia in this setting are incompletely understood. METHODS: We performed a retrospective single-center cohort study of patients with radiologically confirmed ischemic stroke occurring after PCI (PCI-stroke), between January 1, 1994 and December 31, 2009. Using brain imaging, infarctions were subclassified by radiological pattern and arterial territory as embolic, small subcortical, or hemodynamic. Modified Rankin Scale scores were used to assess functional outcome at 3 and 6 months. RESULTS: Radiologically confirmed PCI-stroke was identified in 35 patients. The majority of strokes (91%) revealed an embolic pattern, while the remaining strokes were small subcortical infarctions (9%). Watershed strokes with exclusive borderzone involvement, indicative of a hemodynamic mechanism, were not identified, despite the presence of periprocedural hypotension in 23% of patients. The middle cerebral artery (MCA) territory was affected most frequently (80%), and all patients suffering a complete MCA territorial infarction (14%) died in the hospital. Functional outcome among survivors of PCI-stroke was typically favorable in those who had single rather than multiple vascular territory involvement. CONCLUSIONS: The vast majority of radiologically confirmed ischemic strokes related to PCI are embolic. MCA territory strokes are most common and uniformly fatal when the entire MCA territory is affected. Functional outcomes in survivors of PCI-stroke are improved when only a single arterial territory is affected.

Characterization of a resident population of adventitial macrophage progenitor cells in postnatal vasculature.

RATIONALE: Macrophages regulate blood vessel structure and function in health and disease. The origins of tissue macrophages are diverse, with evidence for local production and circulatory renewal. OBJECTIVE: We identified a vascular adventitial population containing macrophage progenitor cells and investigated their origins and fate. METHODS AND RESULTS: Single-cell disaggregates from adult C57BL/6 mice were prepared from different tissues and tested for their capacity to form hematopoietic colony-forming units. Aorta showed a unique predilection for generating macrophage colony-forming units. Aortic macrophage colony-forming unit progenitors coexpressed stem cell antigen-1 and CD45 and were adventitially located, where they were the predominant source of proliferating cells in the aortic wall. Aortic Sca-1(+)CD45(+) cells were transcriptionally and phenotypically distinct from neighboring cells lacking stem cell antigen-1 or CD45 and contained a proliferative (Ki67(+)) Lin(-)c-Kit(+)CD135(-)CD115(+)CX3CR1(+)Ly6C(+)CD11b(-) subpopulation, consistent with the immunophenotypic profile of macrophage progenitors. Adoptive transfer studies revealed that Sca-1(+)CD45(+) adventitial macrophage progenitor cells were not replenished via the circulation from bone marrow or spleen, nor was their prevalence diminished by depletion of monocytes or macrophages by liposomal clodronate treatment or genetic deficiency of macrophage colony-stimulating factor. Rather adventitial macrophage progenitor cells were upregulated in hyperlipidemic ApoE(-/-) and LDL-R(-/-) mice, with adventitial transfer experiments demonstrating their durable contribution to macrophage progeny particularly in the adventitia, and to a lesser extent the atheroma, of atherosclerotic carotid arteries. CONCLUSIONS: The discovery and characterization of resident vascular adventitial macrophage progenitor cells provides new insight into adventitial biology and its participation in atherosclerosis and provokes consideration of the broader existence of local macrophage progenitors in other tissues.

An in vivo method to quantify lymphangiogenesis in zebrafish.

BACKGROUND: Lymphangiogenesis is a highly regulated process involved in the pathogenesis of disease. Current in vivo models to assess lymphangiogenesis are largely unphysiologic. The zebrafish is a powerful model system for studying development, due to its rapid growth and transparency during early stages of life. Identification of a network of trunk lymphatic capillaries in zebrafish provides an opportunity to quantify lymphatic growth in vivo. METHODS AND RESULTS: Late-phase microangiography was used to detect trunk lymphatic capillaries in zebrafish 2- and 3-days post-fertilization. Using this approach, real-time changes in lymphatic capillary development were measured in response to modulators of lymphangiogenesis. Recombinant human vascular endothelial growth factor (VEGF)-C added directly to the zebrafish aqueous environment as well as human endothelial and mouse melanoma cell transplantation resulted in increased lymphatic capillary growth, while morpholino-based knockdown of vegfc and chemical inhibitors of lymphangiogenesis added to the aqueous environment resulted in decreased lymphatic capillary growth. CONCLUSION: Lymphatic capillaries in embryonic and larval zebrafish can be quantified using late-phase microangiography. Human activators and small molecule inhibitors of lymphangiogenesis, as well as transplanted human endothelial and mouse melanoma cells, alter lymphatic capillary development in zebrafish. The ability to rapidly quantify changes in lymphatic growth under physiologic conditions will allow for broad screening of lymphangiogenesis modulators, as well as help define cellular roles and elucidate pathways of lymphatic development.

Procedural factors associated with percutaneous coronary intervention-related ischemic stroke.

OBJECTIVES: This study sought to determine whether procedural factors during percutaneous coronary intervention (PCI) are associated with the occurrence of ischemic stroke or transient ischemic attack (PCI-stroke). BACKGROUND: Stroke is a devastating complication of PCI. Demographic predictors are nonmodifiable. Whether PCI-stroke is associated with procedural factors, which may be modifiable, is unknown. METHODS: We performed a single-center retrospective study of 21,497 PCI hospitalizations between 1994 and 2008. We compared procedural factors from patients who suffered an ischemic stroke or transient ischemic attack related to PCI (n=79) and a control group (n=158), and matched them 2:1 based on a predicted probability of stroke developed from a logistic regression model. RESULTS: PCI-stroke procedures involved the use of more catheters (median: 3 [quarter (Q) 1, Q3: 3, 4] vs. 3 [Q1, Q3: 2, 3], p<0.001), greater contrast volumes (250 ml vs. 218 ml, p=0.006), and larger guide caliber (median: 7-F [Q1, Q3: 6, 8] vs. 6-F [Q1, Q3: 6, 8], p<0.001). The number of lesions attempted (1.7±0.8 vs. 1.5±0.8, p=0.14) and stents placed (1.4±1.2 vs. 1.2±1.1, p=0.35) were similar between groups, but PCI-stroke patients were more likely to have undergone rotational atherectomy (10% vs. 3%, p=0.029). Overall procedural success was lower in the PCI-stroke group compared with controls (71% vs. 85%, p=0.017). Evaluation of the entire PCI population revealed no difference in the rate of PCI-stroke between radial and femoral approaches (0.4% vs. 0.4%, p=0.78). CONCLUSIONS: Ischemic stroke related to PCI is associated with potentially modifiable technical parameters. Careful procedural planning is warranted, particularly in patients at increased risk.

Identification of a monocyte-predisposed hierarchy of hematopoietic progenitor cells in the adventitia of postnatal murine aorta.

BACKGROUND: Hematopoiesis originates from the dorsal aorta during embryogenesis. Although adult blood vessels harbor progenitor populations for endothelial and smooth muscle cells, it is not known if they contain hematopoietic progenitor or stem cells. Here, we hypothesized that the arterial wall is a source of hematopoietic progenitor and stem cells in postnatal life. METHODS AND RESULTS: Single-cell aortic disaggregates were prepared from adult chow-fed C57BL/6 and apolipoprotein E-null (ApoE(-/-)) mice. In short- and long-term methylcellulose-based culture, aortic cells generated a broad spectrum of multipotent and lineage-specific hematopoietic colony-forming units, with a preponderance of macrophage colony-forming units. This clonogenicity was higher in lesion-free ApoE(-/-) mice and localized primarily to stem cell antigen-1-positive cells in the adventitia. Expression of stem cell antigen-1 in the aorta colocalized with canonical hematopoietic stem cell markers, as well as CD45 and mature leukocyte antigens. Adoptive transfer of labeled aortic cells from green fluorescent protein transgenic donors to irradiated C57BL/6 recipients confirmed the content of rare hematopoietic stem cells (1 per 4 000 000 cells) capable of self-renewal and durable, low-level reconstitution of leukocytes. Moreover, the predominance of long-term macrophage precursors was evident by late recovery of green fluorescent protein-positive colonies from recipient bone marrow and spleen that were exclusively macrophage colony-forming units. Although trafficking from bone marrow was shown to replenish some of the hematopoietic potential of the aorta after irradiation, the majority of macrophage precursors appeared to arise locally, suggesting long-term residence in the vessel wall. CONCLUSIONS: The postnatal murine aorta contains rare multipotent hematopoietic progenitor/stem cells and is selectively enriched with stem cell antigen-1-positive monocyte/macrophage precursors. These populations may represent novel, local vascular sources of inflammatory cells.

Trends, predictors, and outcomes of cerebrovascular events related to percutaneous coronary intervention: a 16-year single-center experience.

OBJECTIVES: We sought to determine trends, predictors, in-hospital and long-term outcomes of cerebrovascular events (CVE) related to percutaneous coronary intervention (PCI) over a 16-year period. BACKGROUND: Despite a temporal increase in patient risk profile and procedural complexity, rates of PCI-related mortality and myocardial infarction have decreased. Temporal trends, characterization, and outcomes after PCI-related CVE in the contemporary era remain unknown. METHODS: We performed a retrospective study of 24,126 PCI hospitalizations in 19,165 unique patients, between January 1, 1994, and December 31, 2009, and compared those who suffered an in-hospital PCI-CVE with the remaining control population who did not. RESULTS: The incidence of CVE was 0.37% (n = 89), of which 22% were transient ischemic attacks. Temporal analysis showed no significant trend in incidence over 16 years (p = 0.47). Multiple clinical and angiographic predictors of PCI-CVE were identified. Multivariate logistic regression analyses revealed age, female sex, myocardial infarction within 7 days before PCI, and history of prior CVE as independent predictors of PCI-CVE, with a 19-fold increase in incidence in patients over 80 with a prior CVE history. In-hospital mortality was 19% after PCI-CVE versus 2% in controls (p < 0.001). Those who survived PCI-CVE exhibited a markedly higher risk of mortality over the subsequent 10 years (p < 0.001). CONCLUSIONS: The incidence of PCI-related CVE has remained steady over a 16-year period, despite an increase in the baseline risk profile. Age and prior history of CVE were the strongest independent demographic predictors. PCI-CVE had a markedly adverse impact on early and late outcomes.

C5 modulates airway hyperreactivity and pulmonary eosinophilia during enhanced respiratory syncytial virus disease by decreasing C3a receptor expression.

Enhanced respiratory syncytial virus disease, a serious pulmonary disorder that affected recipients of an inactivated vaccine against respiratory syncytial virus in the 1960s, has delayed the development of vaccines against the virus. The enhanced disease was characterized by immune complex-mediated airway hyperreactivity and a severe pneumonia associated with pulmonary eosinophilia. In this paper, we show that complement factors contribute to enhanced-disease phenotypes. Mice with a targeted disruption of complement component C5 affected by the enhanced disease displayed enhanced airway reactivity, lung eosinophilia, and mucus production compared to wild-type mice and C5-deficient mice reconstituted with C5. C3aR expression in bronchial epithelial and smooth muscle cells in the lungs of C5-deficient mice was enhanced compared to that in wild-type and reconstituted rodents. Treatment of C5-deficient mice with a C3aR antagonist significantly attenuated airway reactivity, eosinophilia, and mucus production. These results indicate that C5 plays a crucial role in modulating the enhanced-disease phenotype, by affecting expression of C3aR in the lungs. These findings reveal a novel autoregulatory mechanism for the complement cascade that affects the innate and adaptive immune responses.

Driven to tears or to joy: response dominance and trait-based predictions.

The present studies reinvigorate the construct of traitedness from a cognitive perspective. Tendencies toward habit (vs. flexibility) were assessed by examining response dominance performance within choice reaction time tasks. Consistent with the idea that response dominance reflects a tendency toward habitual modes of thought and action, three studies involving 428 undergraduates revealed that trait-outcome and test-retest correlations were higher among individuals higher in response dominance. In Studies 1 and 2, such trait-consistency effects took the form of stronger relations between extraversion and neuroticism, on one hand, and mood states and behavior, on the other. In Study 3, such tendencies took the form of higher test-retest correlations related to daily experiences of mood states, somatic symptoms, and life satisfaction. Together, the studies reveal a consistent effect of response dominance on trait-like consistency and raise some important issues for future studies of the traitedness construct.

The cysteine-rich region of respiratory syncytial virus attachment protein inhibits innate immunity elicited by the virus and endotoxin.

The attachment protein (glycoprotein) of respiratory syncytial virus (RSV) has long been associated with disease potentiation and respiratory symptoms. The glycoprotein has a conserved cysteine-rich region (GCRR) whose function is unknown and which is not necessary for efficient viral replication. In this report, we show that the GCRR is a powerful inhibitor of the innate immune response against RSV, and that early secretion of glycoprotein is critical to modulate inflammation after RSV infection. Importantly, the GCRR is also a potent inhibitor of cytokine production mediated by several TLR agonists, indicating that this peptide sequence displays broad antiinflammatory properties. These findings have important implications for RSV pathogenesis and describe an inhibitor of TLR-mediated inflammatory responses that could have clinical applications.

Mechanisms of illness during respiratory syncytial virus infection: the lungs, the virus and the immune response.

Multiple factors, including cardiopulmonary anatomy, direct viral effects and the immune response can affect the severity of lower respiratory tract disease caused by respiratory syncytial virus (RSV). RSV is the most frequent viral respiratory cause of hospitalization in infants and young children in the world. In this review, we discuss the mechanisms of illness associated with severe RSV lower respiratory tract disease. A better understanding of the factors affecting the course of illness and their interplay should allow development of effective therapies in the future.

Differential production of inflammatory cytokines in primary infection with human metapneumovirus and with other common respiratory viruses of infancy.

Viral respiratory infections are the most frequent cause of hospital admission for infants and young children during winter. However, the mechanisms of illness that are associated with viral lower-respiratory-tract infection (LRI) are unclear. A widely accepted hypothesis attributes the pathogenesis of viral LRI in infants to the induction of innate inflammatory responses. This theory is supported by studies showing that Toll-like receptor 4 is activated by respiratory syncytial virus (RSV), leading to production of inflammatory cytokines. We prospectively examined previously naive infants in Buenos Aires, Argentina, who had either upper- or lower-respiratory-tract symptoms. Infection with human metapneumovirus (hMPV) was second only to RSV in frequency. Both viruses were associated with rhinorrhea, cough, and wheezing; however, hMPV elicited significantly lower levels of respiratory inflammatory cytokines than did RSV. Symptoms in infants infected with influenza virus were different from those in infants infected with RSV, but cytokine responses were similar. These findings suggest that hMPV and RSV either cause disease via different mechanisms or share a common mechanism that is distinct from innate immune activation.

Vaccination of rhesus macaques with a recombinant measles virus expressing interleukin-12 alters humoral and cellular immune responses.

Lack of a vaccine for infants and immunosuppression after infection are problems associated with measles virus (MV). Because interleukin (IL)-12 has been used successfully as a vaccine adjuvant and because inhibition of IL-12 expression has been associated with immunosuppression during measles, the addition of IL-12 may enhance the immune response to MV. To determine the effect of IL-12 supplementation, rhesus macaques were vaccinated with a recombinant MV expressing IL-12; these macaques had increased interferon-gamma production by CD4(+) T cells, decreased production of IL-4, and lower levels of MV-specific immunoglobulin G4 and neutralizing antibody. Lymphoproliferative responses to mitogen were not improved. IL-12 supplementation altered the T helper type 2 bias of the immune response after MV vaccination, had a detrimental effect on the protective neutralizing antibody response, and did not improve other manifestations of immunosuppression. Reduced IL-12 levels are not the sole factor in MV-induced immunosuppression.

Measles virus infection of rhesus macaques affects neutrophil expression of IL-12 and IL-10.

Cytokine production by phagocytic cells is an important component of the immune response to infection with a variety of pathogens. Neutrophils are phagocytic cells capable of expressing interleukin (IL)-12 and IL-10 in response to infection with parasites, fungi, and bacteria. These cytokines are postulated to play important roles in the immune response during measles. Neutrophils isolated from naive or measles virus (MV)-infected rhesus macaques expressed IL-12 and IL-10 following in vitro stimulation with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Stimulated neutrophils secreted proportionally more of the biologically active IL-12 heterodimer p70 and more IL-10 than similarly stimulated peripheral blood mononuclear cells (PBMCs). During MV infection, the number of IL-12 and IL-10-producing neutrophils and monocytes initially decreased. Subsequently, IL-12 levels were restored, and IL-10 expression rose above baseline in both cell types. Increased IL-10 production by neutrophils and monocytes during MV infection may play a role in measles-induced immunosuppression.

A role for nonprotective complement-fixing antibodies with low avidity for measles virus in atypical measles.

In the 1960s, a formalin-inactivated measles vaccine (FIMV) predisposed recipients to atypical measles, an immune complex-mediated disease. To identify characteristics of the immune priming that leads to atypical measles, responses of monkeys to FIMV were compared with responses to live attenuated virus (LAV) and hemagglutinin (H-DNA) vaccines that do not prime for atypical measles. Antibodies induced by FIMV were transient and avidity did not mature. Antibodies induced by LAV and H-DNA vaccines were sustained and avidity matured over time. After challenge with measles virus, FIMV and H-DNA recipients developed high titers of complement-fixing antibodies. In FIMV recipients, the antibodies were of low avidity, whereas in H-DNA vaccine recipients, the antibodies were of high avidity. Neutralizing capacity in B958 cells correlated with avidity. Only FIMV recipients had immune complex deposition. Failure of FIMV to induce affinity maturation results in anamnestic production of nonprotective, complement-fixing antibodies, immune complex deposition and atypical measles.

Differential effects of priming with DNA vaccines encoding the hemagglutinin and/or fusion proteins on cytokine responses after measles virus challenge.

Measles is associated with a million deaths a year in developing countries because of secondary infections. Morbidity is particularly severe in young infants. Both measles-induced immune suppression and atypical measles have been associated with a type 2 cytokine bias of the immune response. The role of individual virus proteins in the induction of these cytokine responses is unknown and could be important for the development of new vaccines. We have used a rhesus macaque model and DNA vaccines to investigate cytokine responses to the individual measles virus (MV) protective antigens, hemagglutinin and fusion. The hemagglutinin protein primed for a type 2 cytokine response, with suppression of interleukin (IL)-12 and preferential production of IL-4 after MV challenge. The fusion protein primed for a type 1 response with preferential production of interferon-gamma. Responses were modulated when both proteins were used for priming. Therefore, the specific proteins included in a new measles vaccine will affect the type of cytokine response elicited.

A role for immune complexes in enhanced respiratory syncytial virus disease.

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and viral pneumonia in infants and young children. Administration of a formalin inactivated vaccine against RSV to children in the 1960s resulted in increased morbidity and mortality in vaccine recipients who subsequently contracted RSV. This incident precluded development of subunit RSV vaccines for infants for over 30 years, because the mechanism of illness was never clarified. An RSV vaccine for infants is still not available. Here, we demonstrate that enhanced RSV disease is mediated by immune complexes and abrogated in complement component C3 and B cell-deficient mice but not in controls. Further, we show correlation with the enhanced disease observed in children by providing evidence of complement activation in postmortem lung sections from children with enhanced RSV disease.

Altered synthesis of interleukin-12 and type 1 and type 2 cytokinesin rhesus macaques during measles and atypical measles.

Immunosuppression during and after measles results in increased susceptibility to other infections and 1 million deaths annually. The mechanism by which measles virus (MV) induces immune suppression is incompletely understood, but a type 2 skewing of the cytokine response after infection has been documented. In vitro studies suggest that lack of interleukin (IL)-12 production by monocytes and dendritic cells plays an early role in the skewed response. In addition, immunization with an inactivated measles vaccine before measles develops appears to lead to an even stronger type 2 skewing of the cytokine response and atypical measles. In this study, the cytokine responses in rhesus macaques were compared after vaccination with live and formalin-inactivated vaccines and after challenge with MV. In vivo production of IL-12 was decreased during the viremic phase of the illness, and production of IL-4 was increased during and after atypical measles, compared with measles.