Search

PURPOSE: Approximately 5.7 million people in the US are affected by congestive heart failure. This study aimed to quantitatively evaluate cardiothoracic morphology and variability within a cohort of heart failure patients for the purpose of optimally engineering cardiac devices for a variety of heart failure patients. METHODS: Co-registered cardiac-gated and non-gated chest computed tomography (CT) scans were analyzed from 20 heart failure patients (12 males; 8 females) who were primarily older adults (79.5±8.8 years). Twelve cardiothoracic measurements were collected and compared to study sex and left ventricular (LV) ejection fraction (EF) type differences in cardiothoracic morphology. RESULTS: Four measures were significantly greater in males compared to females: LV long-axis length, LV end diastolic diameter (LVEDD) at 50% length of the LV long-axis, the minimal distance between the sternum and heart, and the angle between the LV long-axis and coronal plane. Four measures were significantly greater in patients with reduced EF compared to preserved LV: LV long-axis length, LVEDD at 50% length of the LV long-axis, left ventricular volume normalized by body surface area, and the angle between the mitral valve plane and LV long-axis. CONCLUSIONS: These cardiothoracic morphology measurements are important to consider in the design of cardiac devices for heart failure management (e.g. cardiac pacemakers, ventricular assist devices, and implantable defibrillators), since morphology differs by sex and ejection fraction.

Deficiencies in many coagulation factors and protease-activated receptors (PARs) affect embryonic development. We describe a defect in definitive erythropoiesis in PAR2-deficient mice. Embryonic PAR2 deficiency increases embryonic death associated with variably severe anemia in comparison with PAR2-expressing embryos. PAR2-deficient fetal livers display reduced macrophage densities, erythroblastic island areas, and messenger RNA expression levels of markers for erythropoiesis and macrophages. Coagulation factor synthesis in the liver coincides with expanding fetal liver hematopoiesis during midgestation, and embryonic factor VII (FVII) deficiency impairs liver macrophage development. Cleavage-insensitive PAR2-mutant mice recapitulate the hematopoiesis defect of PAR2-deficient embryos, and macrophage-expressed PAR2 directly supports erythroblastic island function and the differentiation of red blood cells in the fetal liver. Conditional deletion of PAR2 in macrophages impairs erythropoiesis, as well as increases inflammatory stress, as evidenced by upregulation of interferon-regulated hepcidin antimicrobial peptide. In contrast, postnatal macrophage PAR2 deficiency does not have any effect on steady-state Kupffer cells, bone marrow macrophage numbers, or erythropoiesis, but erythropoiesis in macrophages from PAR2-deficient mice is impaired following hemolysis. These data identify a novel function for macrophage PAR2 signaling in adapting to rapid increases in blood demand during gestational development and postnatal erythropoiesis under stress conditions.

Objective: Recruitment of neutrophils and formation of neutrophil extracellular traps (NETs) contribute to lethality in acute mesenteric infarction. To study the impact of the gut microbiota in acute mesenteric infarction, we used gnotobiotic mouse models to investigate whether gut commensals prime the reactivity of neutrophils towards formation of neutrophil extracellular traps (NETosis). Approach and Results: We applied a mesenteric ischemia-reperfusion (I/R) injury model to germ-free (GF) and colonized C57BL/6J mice. By intravital imaging, we quantified leukocyte adherence and NET formation in I/R-injured mesenteric venules. Colonization with gut microbiota or monocolonization with Escherichia coli augmented the adhesion of leukocytes, which was dependent on the TLR4 (Toll-like receptor-4)/TRIF (TIR-domain–containing adapter-inducing interferon-β) pathway. Although neutrophil accumulation was decreased in I/R-injured venules of GF mice, NETosis following I/R injury was significantly enhanced compared with conventionally raised mice or mice colonized with the minimal microbial consortium altered Schaedler flora. Also ex vivo, neutrophils from GF and antibiotic-treated mice showed increased LPS (lipopolysaccharide)-induced NETosis. Enhanced TLR4 signaling in GF neutrophils was due to elevated TLR4 expression and augmented IRF3 (interferon regulatory factor-3) phosphorylation. Likewise, neutrophils from antibiotic-treated conventionally raised mice had increased NET formation before and after ischemia. Increased NETosis in I/R injury was abolished in conventionally raised mice deficient in the TLR adaptor TRIF. In support of the desensitizing influence of enteric LPS, treatment of GF mice with LPS via drinking water diminished LPS-induced NETosis in vitro and in the mesenteric I/R injury model. Conclusions: Collectively, our results identified that the gut microbiota suppresses NETing neutrophil hyperreactivity in mesenteric I/R injury, while ensuring immunovigilance by enhancing neutrophil recruitment.

Neutrophils, as the first cellular line of innate host defense, employ phagocytosis and formation of neutrophil extracellular traps (NETs) to combat infections. Classical NET formation induced by phorbol myristate acetate requires several hours to complete. However, recent studies demonstrated rapid NET formation in neutrophils upon stimulation by platelets, Staphylococcus aureus or fungal products. Here we describe that antibody- or complement-induced phagocytosis triggers rapid NET formation. In contrast to classical NETosis, chemical inhibition of NADPH oxidase as well as using NADPH oxidase-deficient patient neutrophils did not affect rapid NET formation. Although phagocytosis and rapid NET formation may not be the prerequisite of each other, cooperation of phagocytosis and rapid NET formation may be essential to improve the efficiency of defense mechanisms in combating disseminating bacteria. Dissecting the differential mechanisms of NET formation is crucial to develop novel therapeutic strategies for infectious and auto-immune diseases where NETs play an essential role.

Expanding evidence indicates multiple interactions between the hemostatic system and innate immunity, and the coagulation and complement cascades. Here we show in a tissue factor (TF)-dependent model of flow restriction-induced venous thrombosis that complement factors make distinct contributions to platelet activation and fibrin deposition. Complement factor 3 (C3) deficiency causes prolonged bleeding, reduced thrombus incidence, thrombus size, fibrin and platelet deposition in the ligated inferior vena cava, and diminished platelet activation in vitro. Initial fibrin deposition at the vessel wall over 6 hours in this model was dependent on protein disulfide isomerase (PDI) and TF expression by myeloid cells, but did not require neutrophil extracellular trap formation involving peptidyl arginine deiminase 4. In contrast to C3-/- mice, C5-deficient mice had no apparent defect in platelet activation in vitro, and vessel wall platelet deposition and initial hemostasis in vivo. However, fibrin formation, the exposure of negatively charged phosphatidylserine (PS) on adherent leukocytes, and clot burden after 48 hours were significantly reduced in C5-/- mice compared with wild-type controls. These results delineate that C3 plays specific roles in platelet activation independent of formation of the terminal complement complex and provide in vivo evidence for contributions of complement-dependent membrane perturbations to prothrombotic TF activation on myeloid cells.

Mesenchymal stem cells (MSCs) are crucial for tissue homeostasis and regeneration. Though of prime interest, their potentially protective role on neutrophil-induced tissue damage, associated with high morbidity and mortality, has not been explored in sufficient detail. Here we report the therapeutic skill of MSCs to suppress unrestrained neutrophil activation and to attenuate severe tissue damage in a murine immune-complex mediated vasculitis model of unbalanced neutrophil activation. MSC-mediated neutrophil suppression was due to intercellular adhesion molecule 1-dependent engulfment of neutrophils by MSCs, decreasing overall neutrophil numbers. Similar to MSCs in their endogenous niche of murine and human vasculitis, therapeutically injected MSCs via upregulation of the extracellular superoxide dismutase (SOD3), reduced superoxide anion concentrations and consequently prevented neutrophil death, neutrophil extracellular trap formation and spillage of matrix degrading neutrophil elastase, gelatinase and myeloperoxidase. SOD3-silenced MSCs did not exert tissue protective effects. Thus, MSCs hold substantial therapeutic promise to counteract tissue damage in conditions with unrestrained neutrophil activation.

The extracellular adherence protein (Eap) of Staphylococcus aureus is a secreted protein known to exert a number of adhesive and immunomodulatory properties. Here we describe the intrinsic DNA binding activity of this multifunctional secretory factor. By using atomic force microscopy, we provide evidence that Eap can bind and aggregate DNA. While the origin of the DNA substrate (e.g., eukaryotic, bacterial, phage, and artificial DNA) seems to not be of major importance, the DNA structure (e.g., linear or circular) plays a critical role with respect to the ability of Eap to bind and condense DNA. Further functional assays corroborated the nature of Eap as a DNA binding protein, since Eap suppressed the formation of "neutrophil extracellular traps" (NETs), composed of DNA-histone scaffolds, which are thought to function as a neutrophil-mediated extracellular trapping mechanism. The DNA binding and aggregation activity of Eap may thereby protect S. aureus against a specific anti-microbial defense reaction from the host.

Deficiencies in many coagulation factors and protease-activated receptors (PARs) affect mouse embryonic development, but phenotypes of single PAR-deficiencies are often obscured by compensation by other receptors. Although most PAR1/PAR2 double deficient embryos do not survive to birth, PAR2 single-deficient embryos exhibit an unresolved partial preterm lethality. We have observed that PAR2-/- embryos at day 13.5 to 15.5 p.c. from timed mating of homozygous PAR2-/- parents display an increased embryonic death and growth retardation as well as variable signs of anemia in comparison to WT embryos of the same gestational age. The pale appearance suggested that PAR2 might play a role during fetal hematopoiesis. To investigate whether this phenotype is merely a consequence of a previously demonstrated placental defect arising from PAR2 deficiency in the mother, we compared heterozygous PAR2+/- embryos produced by timed-mating of WT mothers mated with PAR2-/- fathers or of PAR2-/- mother mated with WT father. Although reduced embryo weights in PAR2-/- relative to WT mothers indicated a developmental delay due to maternal PAR2 deficiency, anemia was not observed in these PAR2+/- embryos. The fetal liver is the site of hematopoiesis during embryonic development. We therefore evaluated fetal hematopoiesis at day 13.5 to 15.5 p.c. in PAR2+/- and PAR2-/- embryos from timed mated heterozygous PAR2+/- mothers mated with PAR2-/- fathers. Macroscopic phenotypic abnormalities, including signs of anemia, were more prevalent in PAR2-/- versus PAR2+/- embryos, demonstrating an embryonic phenotype that develops independent from maternal PAR2-deficiency. Gene expression analyses of fetal liver at day 13.5 p.c. showed a reduction in marker genes for erythropoiesis, i.e. beta-globin, GATA-1, BCL-11a and for macrophages, i.e. F4/80, Id3, Nr1h3, specifically in PAR2-/- relative to PAR2+/- embryos. These differences were also seen at day 15.5 p.c. in homozygous PAR2 R38E cleavage resistant relative to PAR2 R38E/WT heterozygous embryos in the same litter, confirming PAR2 proteolytic signaling as the major regulator of fetal hematopoiesis. Since macrophage markers in the fetal liver were reduced in PAR2-/- embryos, we next evaluated the role of macrophage PAR2 signaling by cell-type specific deletion in PAR2flfl-LysMcre mice. Macrophage PAR2-deficient mice had reduced erythroblast islands, and erythropoiesis and macrophage marker genes were reduced in the fetal liver at day 15.5 p.c. to the same extent as seen in completely PAR2-deficient embryos. Blood island macrophages play pivotal roles in erythrophagocytosis and clearance of red blood cell expelled nuclei. Deficiency in red blood cell nuclei clearance, e.g. in DNase I deficient mice, causes macrophage inflammatory activation and upregulation of the interferon regulated gene Hamp-1. PAR2flfl-LysMcre fetal livers showed increased Hamp-1 expression relative to cre-negative controls from the same pregnancy, further indicating that macrophage PAR2 signaling directly participates in the regulation of erythropoiesis. These data identify a novel function for proteolytic PAR2 activation in the supporting fetal hematopoiesis and raise the possibility that PAR2 signaling may also regulate adult hematopoiesis under stress conditions or aging. Disclosures No relevant conflicts of interest to declare.

Neutrophils, the most abundant human immune cells, are rapidly recruited to sites of infection, where they fulfill their life-saving antimicrobial functions. While traditionally regarded as short-lived phagocytes, recent findings on long-term survival, neutrophil extracellular trap (NET) formation, heterogeneity and plasticity, suppressive functions, and tissue injury have expanded our understanding of their diverse role in infection and inflammation. This review summarises our current understanding of neutrophils in host-pathogen interactions and disease involvement, illustrating the versatility and plasticity of the neutrophil, moving between host defence, immune modulation, and tissue damage.

Minimally invasive surgical technique (MIS) is difficult to master due to its inherent complexity imposed by reduced work volume and limited flexibility in motions. In traditional MIS training, faculty surgeons evaluate junior surgeon's performance using subjective and resource-intensive methods lacking quantitative rigour. Although recent technological advancement in surgical education has enabled more objective and automated evaluation of surgical skill, most of measures are still task-specific and thus can be hardly generalised across different operations and platforms. Therefore, this research studies a novel framework for generalised performance measure based on the analysis of non-linear dynamics in surgical motions. Specifically, surgical motions are recorded using motion sensors attached on instruments during surgical exercises. Then, intensity of recurrences in the motion data is calculated and disorder index is computed using the intensity of recurrences. The test results have shown that disorder index values can be used to quantify surgical skill levels.

Posttranslational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is well studied in the nervous system and described as a dynamic modulator of plastic processes like precursor cell migration, axon fasciculation, and synaptic plasticity. Here, we describe a novel function of polysialylated NCAM (polySia-NCAM) in innate immunity of the lung. In mature lung tissue of healthy donors, polySia was exclusively attached to the transmembrane isoform NCAM-140 and located to intracellular compartments of epithelial cells. In patients with chronic obstructive pulmonary disease, however, increased polySia levels and processing of the NCAM carrier were observed. Processing of polysialylated NCAM was reproduced in a mouse model by bleomycin administration leading to an activation of the inflammasome and secretion of interleukin (IL)-1β. As shown in a cell culture model, polySia-NCAM-140 was kept in the late trans-Golgi apparatus of lung epithelial cells and stimulation by IL-1β or lipopolysaccharide induced metalloprotease-mediated ectodomain shedding, resulting in the secretion of soluble polySia-NCAM. Interestingly, polySia chains of secreted NCAM neutralized the cytotoxic activity of extracellular histones as well as DNA/histone-network-containing "neutrophil extracellular traps", which are formed during invasion of microorganisms. Thus, shedding of polySia-NCAM by lung epithelial cells may provide a host-protective mechanism to reduce tissue damage during inflammatory processes.