Sevoflurane Exerts Protective Effects in Murine Peritonitis-induced Sepsis via Hypoxia-inducible Factor 1α/Adenosine A2B Receptor Signaling.

BACKGROUND: Sepsis is one of the leading causes of mortality in intensive care units, and sedation in the intensive care unit during sepsis is usually performed intravenously. The inhalative anesthetic sevoflurane has been shown to elicit protective effects in various inflammatory studies, but its role in peritonitis-induced sepsis remains elusive. The hypothesis was that sevoflurane controls the neutrophil infiltration by stabilization of hypoxia-inducible factor 1α and elevated adenosine A2B receptor expression. METHODS: In mouse models of zymosan- and fecal-induced peritonitis, male mice were anesthetized with sevoflurane (2 volume percent, 30 min) after the onset of inflammation. Control animals received the solvent saline. The neutrophil counts and adhesion molecules on neutrophils in the peritoneal lavage of wild-type, adenosine A2B receptor -/-, and chimeric animals were determined by flow cytometry 4 h after stimulation. Cytokines and protein release were determined in the lavage. Further, the adenosine A2B receptor and its transcription factor hypoxia-inducible factor 1α were evaluated by real-time polymerase chain reaction and Western blot analysis 4 h after stimulation. RESULTS: Sevoflurane reduced the neutrophil counts in the peritoneal lavage (mean ± SD, 25 ± 17 × 105vs. 12 ± 7 × 105 neutrophils; P = 0.004; n = 19/17) by lower expression of various adhesion molecules on neutrophils of wild-type animals but not of adenosine A2B receptor -/- animals. The cytokines concentration (means ± SD, tumor necrosis factor α [pg/ml], 523 ± 227 vs. 281 ± 101; P = 0.002; n = 9/9) and protein extravasation (mean ± SD [mg/ml], 1.4 ± 0.3 vs. 0.8 ± 0.4; P = 0.002; n = 12/11) were also lower after sevoflurane only in the wild-type mice. Chimeric mice showed the required expression of the adenosine A2B receptor on the hematopoietic and nonhematopoietic compartments for the protective effects of the anesthetic. Sevoflurane induced the expression of hypoxia-inducible factor 1α and adenosine A2B receptor in the intestine, liver, and lung. CONCLUSIONS: Sevoflurane exerts various protective effects in two murine peritonitis-induced sepsis models. These protective effects were linked with a functional adenosine A2B receptor.

The Pivotal Role of CXCR7 in Stabilization of the Pulmonary Epithelial Barrier in Acute Pulmonary Inflammation.

Acute pulmonary inflammation is still a frightening complication in intensive care units and has a high mortality. Specific treatment is not available, and many details of the pathomechanism remain unclear. The recently discovered chemokine receptor CXCR7 and its ligand stromal cell-derived factor (SDF)-1 are known to be involved in inflammation. We chose to investigate the detailed role of CXCR7 in a murine model of LPS inhalation. Inflammation increased pulmonary expression of CXCR7, and the receptor was predominantly expressed on pulmonary epithelium and on polymorphonuclear neutrophil (PMNs) after transepithelial migration into the alveolar space. Specific inhibition of CXCR7 reduced transepithelial PMN migration by affecting the expression of adhesion molecules. CXCR7 antagonism reduced the most potent PMN chemoattractants CXCL1 and CXCL2/3. After inhibiting CXCR7, NF-κB phosphorylation was reduced in lungs of mice, tight junction formation increased, and protein concentration in the bronchoalveolar lavage diminished, showing the impact of CXCR7 on stabilizing microvascular permeability. In vitro studies with human cells confirmed the pivotal role of CXCR7 in pulmonary epithelium. Immunofluorescence of human lungs confirmed our in vivo data and showed an increase of the expression of CXCR7 in pulmonary epithelium. Highlighting the clinical potential of CXCR7 antagonism, nebulization of the agent before and after the inflammation showed impressive anti-inflammatory effects. Additional CXCR7 inhibition potentiated the effect of SDF-1 antagonism, most probably by downregulating SDF-1 and the second receptor of the chemokine (CXCR4) expression. In conclusion, our data identified the pivotal role of the receptor CXCR7 in pulmonary inflammation with a predominant effect on the pulmonary epithelium and PMNs.

How Adhesion Molecule Patterns Change While Neutrophils Traffic through the Lung during Inflammation.

In acute pulmonary inflammation, polymorphonuclear cells (PMNs) pass a transendothelial barrier from the circulation into the lung interstitium followed by a transepithelial migration into the alveolar space. These migration steps are regulated differentially by a concept of adhesion molecules and remain-despite decades of research-incompletely understood. Current knowledge of changes in the expression pattern of adhesion molecules mainly derives from in vitro studies or from studies in extrapulmonary organ systems, where regulation of adhesion molecules differs significantly. In a murine model of lung inflammation, we determined the expression pattern of nine relevant neutrophilic adhesion molecules on their way through the different compartments of the lung. We used a flow cytometry-based technique that allowed describing spatial distribution of the adhesion molecules expressed on PMNs during their migration through the lung in detail. For example, the highest expression of CD29 was found in the intravascular compartment, highlighting its impact on the initial adhesion to the endothelium. CD47 showed its peak of expression on the later phase of transendothelial migration, whereas CD11b and CD54 expression peaked interstitial. A pivotal role for transepithelial migration was found for the adhesion molecule CD172a. Thereby, expression may correlate with functional impact for specific migration steps. In vitro studies further confirmed our in vivo findings. In conclusion, we are the first to determine the changes in expression patterns of relevant adhesion molecules on their migration through the different compartments of the lung. These findings may help to further understand the regulation of neutrophil trafficking in the lung.

Improved recognition of ineffective chest compressions after a brief Crew Resource Management (CRM) training: a prospective, randomised simulation study.

BACKGROUND: Chest compressions are a core element of cardio-pulmonary resuscitation. Despite periodic training, real-life chest compressions have been reported to be overly shallow and/or fast, very likely affecting patient outcomes. We investigated the effect of a brief Crew Resource Management (CRM) training program on the correction rate of improperly executed chest compressions in a simulated cardiac arrest scenario. METHODS: Final-year medical students (n = 57) were randomised to receive a 10-min computer-based CRM or a control training on ethics. Acting as team leaders, subjects performed resuscitation in a simulated cardiac arrest scenario before and after the training. Team members performed standardised overly shallow and fast chest compressions. We analysed how often the team leader recognised and corrected improper chest compressions, as well as communication and resuscitation quality. RESULTS: After the CRM training, team leaders corrected improper chest compressions (35.5%) significantly more often compared with those undergoing control training (7.7%, p = 0.03*). Consequently, four students have to be trained (number needed to treat = 3.6) for one improved chest compression scenario. Communication quality assessed by the Leader Behavior Description Questionnaire significantly increased in the intervention group by a mean of 4.5 compared with 2.0 (p = 0.01*) in the control group. CONCLUSION: A computer-based, 10-min CRM training improved the recognition of ineffective of chest compressions. Furthermore, communication quality increased. As guideline-adherent chest compressions have been linked to improved patient outcomes, our CRM training might represent a brief and affordable approach to increase chest compression quality and potentially improve patient outcomes.

Gαi2 is the essential Gαi protein in immune complex-induced lung disease.

Heterotrimeric G proteins of the Gα(i) family have been implicated in signaling pathways regulating cell migration in immune diseases. The Gα(i)-protein-coupled C5a receptor is a critical regulator of IgG FcR function in experimental models of immune complex (IC)-induced inflammation. By using mice deficient for Gα(i2) or Gα(i3), we show that Gα(i2) is necessary for neutrophil influx in skin and lung Arthus reactions and agonist-induced neutrophilia in the peritoneum, whereas Gα(i3) plays a less critical but variable role. Detailed analyses of the pulmonary IC-induced inflammatory response revealed several shared functions of Gα(i2) and Gα(i3), including mediating C5a anaphylatoxin receptor-induced activation of macrophages, involvement in alveolar production of chemokines, transition of neutrophils from bone marrow into blood, and modulation of CD11b and CD62L expression that account for neutrophil adhesion to endothelial cells. Interestingly, C5a-stimulated endothelial polymorphonuclear neutrophil transmigration, but not chemotaxis, is enhanced versus reduced in the absence of neutrophil Gα(i3) or Gα(i2), respectively, and knockdown of endothelial Gα(i2) caused decreased transmigration of wild-type neutrophils. These data demonstrate that Gα(i2) and Gα(i3) contribute to inflammation by redundant, overlapping, and Gα(i)-isoform-specific mechanisms, with Gα(i2) exhibiting unique functions in both neutrophils and endothelial cells that appear essential for polymorphonuclear neutrophil recruitment in IC disease.

Heme oxygenase-1 attenuates acute pulmonary inflammation by decreasing the release of segmented neutrophils from the bone marrow.

Recruiting polymorphonuclear neutrophil granulocytes (PMNs) from circulation and bone marrow to the site of inflammation is one of the pivotal mechanisms of the innate immune system. During inflammation, the enzyme heme oxygenase 1 (HO-1) has been shown to reduce PMN migration. Although these effects have been described in various models, underlying mechanisms remain elusive. Recent studies revealed an influence of HO-1 on different cells of the bone marrow. We investigated the particular role of the bone marrow in terms of HO-1-dependent pulmonary inflammation. In a murine model of LPS inhalation, stimulation of HO-1 by cobalt (III) protoporphyrin-IX-chloride (CoPP) resulted in reduced segmented PMN migration into the alveolar space. In the CoPP group, segmented PMNs were also decreased intravascularly, and concordantly, mature and immature PMN populations were higher in the bone marrow. Inhibition of the enzyme by tin protoporphyrin-IX increased segmented and banded PMN migration into the bronchoalveolar lavage fluid with enhanced PMN release from the bone marrow and aggravated parameters of tissue inflammation. Oxidative burst activity was significantly higher in immature compared with mature PMNs. The chemokine stromal-derived factor-1 (SDF-1), which mediates homing of leukocytes into the bone marrow and is decreased in inflammation, was increased by CoPP. When SDF-1 was blocked by the specific antagonist AMD3100, HO-1 activation was no longer effective in curbing PMN trafficking to the inflamed lungs. In conclusion, we show evidence that the anti-inflammatory effects of HO-1 are largely mediated by inhibiting the release of segmented PMNs from the bone marrow rather than direct effects within the lung.

Protective effects of pentoxifylline in pulmonary inflammation are adenosine receptor A2A dependent.

Pentoxifylline (PTX) has been shown to exert anti-inflammatory effects in experimental acute lung injury. However, results in humans were controversial. Recent in vitro studies suggested that the adenosine receptor A2A may be required for PTX to be effective. Therefore, we studied the association between A2A and PTX in a murine model of LPS-induced pulmonary inflammation. PTX treatment (10 mg/kg) reduced cellular influx (by 40%), microvascular permeability (30%), and the release of chemotactic cytokines into the alveolar space (TNF-α 60%, IL-6 60%, and CXCL2/3 53%, respectively). These protective effects were abolished completely in A2A(-/-) mice and in wild-type mice that had been treated with the selective A2A antagonist (1 mg/kg), but effects were not different in mice with altered adenosine levels. In vitro transmigration assays revealed a pivotal role of the endothelium in PTX-mediated PMN migration, with a reduction of 50% (2 mM PTX). This effect was also A2A dependent. Further, oxidative burst of human PMNs was A2A-dependently reduced by 53% after PTX treatment. In summary, PTX exhibits its anti-inflammatory effects in LPS-induced lung injury through an A2A-dependent pathway. These results will help to better understand previous conflicting data on PTX in inflammation and will direct further studies to consider the predominant role of A2A.

Basic life support is effectively taught in groups of three, five and eight medical students: a prospective, randomized study.

BACKGROUND: Resuscitation is a life-saving measure usually instructed in simulation sessions. Small-group teaching is effective. However, feasible group sizes for resuscitation classes are unknown. We investigated the impact of different group sizes on the outcome of resuscitation training. METHODS: Medical students (n = 74) were randomized to courses with three, five or eight participants per tutor. The course duration was adjusted according to the group size, so that there was a time slot of 6 minutes hands-on time for every student. All participants performed an objective structured clinical examination before and after training. The teaching sessions were videotaped and resuscitation quality was scored using a checklist while we measured the chest compression parameters with a manikin. In addition, we recorded hands-on-time, questions to the tutor and unrelated conversation. RESULTS: Results are displayed as median (IQR). Checklist pass rates and scores were comparable between the groups of three, five and eight students per tutor in the post-test (93%, 100% and 100%). Groups of eight students asked fewer questions (0.5 (0.0 - 1.0) vs. 3.0 (2.0 - 4.0), p < .001), had less hands-on time (2:16 min (1:15 - 4:55 min) vs. 4:07 min (2:54 - 5:52 min), p = .02), conducted more unrelated conversations (17.0 ± 5.1 and 2.9 ± 1.7, p < 0.001) and had lower self-assessments than groups of three students per tutor (7.0 (6.1 - 9.0) and 8.2 (7.2 - 9.0), p = .03). CONCLUSIONS: Resuscitation checklist scores and pass rates after training were comparable in groups of three, five or eight medical students, although smaller groups had advantages in teaching interventions and hands-on time. Our results suggest that teaching BLS skills is effective in groups up to eight medical students, but smaller groups yielded more intense teaching conditions, which might be crucial for more complex skills or less advanced students.

Impact of anesthetics on 3'-[18F]fluoro-3'-deoxythymidine ([18F]FLT) uptake in animal models of cancer and inflammation.

The aim of this study was to evaluate the impact of different anesthetics on 3'-[18F]fluoro-3'-deoxythymidine ([18F]FLT) uptake in carcinomas and arthritic ankles. To determine the amount of [18F]FLT uptake in subcutaneous CT26 colon carcinomas or arthritic ankles, spontaneously room air/medical air-breathing mice were anesthetized with isoflurane, a combination of medetomidine/midazolam, or ketamine/xylazine. Mice were kept conscious or anesthetized during [18F]FLT uptake before the 10-minute static positron emission tomographic (PET) investigations. [18F]FLT uptake in CT26 colon carcinomas and arthritic ankles was calculated by drawing regions of interest. We detected a significantly reduced (4.4 ± 0.9 %ID/cm3) [18F]FLT uptake in the carcinomas of ketamine/xylazine-anesthetized mice compared to the [18F]FLT-uptake in carcinomas of medetomidine/midazolam- (7.0 ± 1.5 %ID/cm3) or isoflurane-anesthetized mice (6.4 ± 1.5 %ID/cm3), whereas no significant differences were observed in arthritic ankles regardless of whether mice were anesthetized or conscious during tracer uptake. The time-activity curves of carcinomas and arthritic ankles yielded diverse [18F]FLT accumulation related to the used anesthetics. [18F]FLT uptake dynamics are different in arthritic ankles and carcinoma, and the magnitude and pharmacokinetics of [18F]FLT uptake are sensitive to anesthetics. Thus, for preclinical in vivo [18F]FLT PET studies in experimental tumor or inflammation models, we recommend the use of isoflurane anesthesia as it yields a stable tracer uptake and is easy to handle.

Adenosine receptor A2b on hematopoietic cells mediates LPS-induced migration of PMNs into the lung interstitium.

Uncontrolled transmigration of polymorphonuclear leukocytes (PMNs) into the different compartments of the lungs (intravascular, interstitial, alveolar) is a critical event in the early stage of acute lung injury and acute respiratory distress syndrome. Adenosine receptor A(2b) is highly expressed in the inflamed lungs and has been suggested to mediate cell trafficking. In a murine model of LPS-induced lung inflammation, we investigated the role of A(2b) on migration of PMNs into the different compartments of the lung. In A(2b)(-/-) mice, LPS-induced accumulation of PMNs was significantly higher in the interstitium, but not in the alveolar space. In addition, pulmonary clearance of PMNs was delayed in A(2b)(-/-) mice. Using chimeric mice, we identified A(2b) on hematopoietic cells as crucial for PMN migration. A(2b) did not affect the release of relevant chemokines into the alveolar space. LPS-induced microvascular permeability was under the control of A(2b) on both hematopoietic and nonhematopoietic cells. Activation of A(2b) on endothelial cells also reduced formation of LPS-induced stress fibers, highlighting its role for endothelial integrity. A specific A(2b) agonist (BAY 60-6583) was effective in decreasing PMN migration into the lung interstitium and microvascular permeability. In addition, in vitro transmigration of human PMNs through a layer of human endothelial or epithelial cells was A(2b) dependent. Activation of A(2b) on human PMNs reduced oxidative burst activity. Together, our results demonstrate anti-inflammatory effects of A(2b) on two major characteristics of acute lung injury, with a distinct role of hematopoietic A(2b) for cell trafficking and endothelial A(2b) for microvascular permeability.

Adenosine receptor A1 regulates polymorphonuclear cell trafficking and microvascular permeability in lipopolysaccharide-induced lung injury.

Extracellular adenosine and adenosine receptors are critically involved in various inflammatory pathways. Adenosine receptor A1 (A1AR) has been implicated in mediating transmigration of leukocytes to sites of inflammation. This study was designed to characterize the role of A1AR in a murine model of LPS-induced lung injury. LPS-induced transmigration of polymorphonuclear cells (PMNs) and microvascular permeability was elevated in A1AR(-/-) mice. Pretreatment of wild-type mice with the specific A1AR agonist 2'Me-2-chloro-N6-cyclopentyladenosine attenuated PMN accumulation in the interstitium and alveolar space as well as microvascular permeability. Lower PMN counts in the lungs of pretreated wild-type mice were associated with reduced amounts of the chemotactic cytokines TNF-α, IL-6, and CXCL2/3 in the bronchoalveolar lavage. Pretreatment was only effective when A1AR was expressed on hematopoietic cells as demonstrated in chimeric mice. These findings were confirmed by in vitro transmigration assays demonstrating that chemokine-induced transmigration of PMNs was reduced when PMNs but not when pulmonary endothelial or alveolar epithelial cells were pretreated. 2'Me-2-chloro-N6-cyclopentyladenosine prevented pulmonary endothelial but not epithelial cells from LPS-induced cellular remodeling and cell retraction. Our data reveal what we believe to be a previously unrecognized distinct role of A1AR for PMN trafficking and endothelial integrity in a model of acute lung injury.

Occurrence and Severity of Venous Air Embolism During Neurosurgical Procedures: Semisitting Versus Supine Position.

BACKGROUND: At our institution, patients undergoing neurosurgical procedures in the posterior cranial fossa are placed either in the semisitting or in the supine position. The major risk of the semisitting positioning is a venous air embolism (VAE), which may, however, also occur in the supine position. METHODS: In a prospective single-center study with 137 patients, we evaluated the occurrence of VAEs in patients in the supine and in the semisitting position during the period from January 2014 until April 2015. All patients were monitored for VAE by the use of a transesophageal echocardiography (TEE). RESULTS: In total, 50% of the patients experienced a VAE (56% of these patients underwent surgery in the semisitting and 11% in the supine position). In total, 86% of the VAEs were detected by the use of a TEE and did not lead to any changes in the end-expiratory CO2. We only observed VAEs with a decrease in end-expiratory CO2 in the semisitting position. However, none of the patients had any hemodynamic changes due to the VAE. CONCLUSIONS: The semisitting position with TEE monitoring and a standardized protocol is a safe and advantageous technique, taking account of a significant rate of VAEs. VAEs also occur in the supine position, but less frequently.

Fractalkine Is Linked to the Necrosome Pathway in Acute Pulmonary Inflammation.

Acute pulmonary inflammation affects over 10% of intensive care unit (ICU) patients and is associated with high mortality. Fractalkine (CX3CL1) and its receptor, CX3CR1, have been shown to affect pulmonary inflammation, but previous studies have focused on macrophages. In a murine model of acute pulmonary inflammation, we identified inflammatory hallmarks in C57BL/6J and CX3CR1-/- mice. Pulmonary inflammation was significantly enhanced in the CX3CR1-/- animals compared to the C57BL/6J animals, as assessed by microvascular permeability, polymorphonuclear neutrophil (PMN) migration into lung tissue and alveolar space. The CX3CR1-/- mice showed increased levels of apoptotic PMNs in the lungs, and further investigations revealed an increased activation of necrosome-related receptor-interacting serine/threonine-protein kinases 1 (RIPK1), 3 (RIPK3), and mixed-lineage kinase domain-like pseudokinase (MLKL). Phosphorylated MLKL leads to membrane rupture and damage-associated molecular pattern (DAMP) release, which further enhance inflammation. The release of DAMPs was significantly higher in the CX3CR1-/- mice and led to the activation of various cascades, explaining the increased inflammation. RIPK3 and MLKL inhibition improved the inflammatory response in human PMNs in vitro and confirmed our in vivo findings. In conclusion, we linked CX3CL1 to the necrosome complex in pulmonary inflammation and demonstrated a pivotal role of the necrosome complex in human PMNs.

Importance of CXC chemokine receptor 2 in alveolar neutrophil and exudate macrophage recruitment in response to pneumococcal lung infection.

Sustained neutrophilic infiltration is known to contribute to organ damage, such as acute lung injury. CXC chemokine receptor 2 (CXCR2) is the major receptor regulating inflammatory neutrophil recruitment in acute and chronic inflamed tissues. Whether or not the abundant neutrophil recruitment observed in severe pneumonia is essential for protective immunity against Streptococcus pneumoniae infections is incompletely defined. Here we show that CXCR2 deficiency severely perturbs the recruitment of both neutrophils and exudate macrophages associated with a massive bacterial outgrowth in distal airspaces after infection with S. pneumoniae, resulting in 100% mortality in knockout (KO) mice within 3 days. Moreover, irradiated wild-type mice reconstituted with increasing amounts of CXCR2 KO bone marrow (10, 25, 50, and 75% KO) have correspondingly decreased numbers of both neutrophils and exudate macrophages, which is associated with a stepwise increase in bacterial burden and a reciprocal stepwise decrease in survival in S. pneumoniae-induced pulmonary infection. Finally, application of the CXCR2 antagonist SB-225002 resulted in decreased alveolar neutrophil and exudate macrophage recruitment in mice along with increased lung bacterial loads after infection with S. pneumoniae. Together, these data show that CXC chemokine receptor 2 serves a previously unrecognized nonredundant role in the regulation of both neutrophil and exudate macrophage recruitment to the lung in response to S. pneumoniae infection. In addition, we demonstrate that a threshold level of 10 to 25% of reduced neutrophil recruitment is sufficient to cause increased mortality in mice infected with S. pneumoniae.

Adenosine receptor A3 is a critical mediator in LPS-induced pulmonary inflammation.

Adenosine receptor A(3) (A(3)) regulates directed movement of polymorphonuclear cells (PMNs) to sites of inflammation and has been implicated as a relevant mediator in models of inflammatory diseases. Here, we sought to characterize the role of A(3) in a murine model of lung inflammation. Initial studies revealed that pulmonary A(3) transcript levels were elevated following LPS exposure in vivo. In addition, inhalation of LPS increased the accumulation of PMNs in wild-type and A(3)(-/-) mice in all lung compartments. Pretreatment with the specific A(3)-agonist Cl-IB-MECA significantly decreased migration of PMNs into lung interstitium and alveolar air space of wild-type mice but not of A(3)(-/-) mice. Lower PMN counts were associated with reduced levels of TNF-α and IL-6 in the alveolar space of wild-type mice that received Cl-IB-MECA. In addition, Cl-IB-MECA attenuated LPS-induced microvascular permeability in wild-type mice as assessed by the extravasation of Evans blue. In pulmonary microvascular endothelial cells, Cl-IB-MECA reduced LPS-induced cytoskeletal remodeling and cell retraction, consistent with a specific role of A(3) for maintaining endothelial integrity. Migratory activity of human PMNs across an endothelial or epithelial monolayer was reduced when A(3) was activated on PMNs. Studies in chimeric mice, however, revealed that Cl-IB-MECA required A(3) on both hematopoietic and nonhematopoietic cells to reduce transmigration in vivo. Together, our results shed new light on the role of A(3) in LPS-induced PMN trafficking in the lung and suggest pharmacological modulation of A(3)-dependent pathways as a promising approach in lung inflammation.

DARC on RBC limits lung injury by balancing compartmental distribution of CXC chemokines.

The Duffy antigen receptor for chemokines (DARC) has a high affinity for CC and CXC chemokines. However, it lacks the ability to induce cell responses that are typical for classical chemokine receptors. The role of DARC in inflammatory conditions remains to be elucidated. We studied the role of DARC in a murine model of acute lung injury. We found that in Darc-gene-deficient (Darc(-/-)) mice, LPS-induced PMN migration into the alveolar space was elevated more than twofold. In contrast, PMN adhesion to endothelial cells and within the interstitial space was reduced in Darc(-/-) mice. Darc(-/-) mice also exhibited increased microvascular permeability. Elevated PMN migration in Darc(-/-) mice was associated with increased concentrations of two essential CXCR2 ligands, CXCL1 and CXCL2/3 in the alveolar space. In the blood, CXCL1 was mostly associated with RBC in WT mice and with plasma in Darc(-/-) mice. We found that DARC on RBC prevented excessive PMN migration into the alveolar space. In contrast, DARC on non-hematopoietic cells appeared to have only minor effects on leukocyte trafficking in this model. These findings show how DARC regulates lung inflammation by controlling the distribution and presentation of chemokines that bind CXCR2.

Adenosine and inflammation: CD39 and CD73 are critical mediators in LPS-induced PMN trafficking into the lungs.

Extracellular adenosine has been implicated as anti-inflammatory signaling molecule during acute lung injury (ALI). The main source of extracellular adenosine stems from a coordinated two-step enzymatic conversion of precursor nucleotides via the ecto-apyrase (CD39) and the ecto-5'-nucleotidase (CD73). In the present study, we hypothesized a critical role of CD39 and CD73 in mediating pulmonary neutrophil (PMN) transmigration during lipopolysaccharide (LPS) -induced lung injury. Initial studies revealed that pulmonary CD39 and CD73 transcript levels were elevated following LPS exposure in vivo. Moreover, LPS-induced accumulation of PMN into the lungs was enhanced in cd39(-/-) or cd73(-/-) mice, particularly into the interstitial and intra-alveolar compartment. Such increases in PMN trafficking were accompanied by corresponding changes in alveolar-capillary leakage. Similarly, inhibition of extracellular nucleotide phosphohydrolysis with the nonspecific ecto-nucleoside-triphosphate-diphosphohydrolases inhibitor POM-1 confirmed increased pulmonary PMN accumulation in wild-type, but not in gene-targeted mice for cd39 or cd73. Finally, treatment with apyrase or nucleotidase was associated with attenuated pulmonary neutrophil accumulation and pulmonary edema during LPS-induced lung injury. Taken together, these data reveal a previously unrecognized role for CD39 and CD73 in attenuating PMN trafficking into the lungs during LPS-induced lung injury and suggest treatment with their soluble compounds as a therapeutic strategy.

Induction of vascular permeability: beta PIX and GIT1 scaffold the activation of extracellular signal-regulated kinase by PAK.

Increased permeability of blood vessels is an important component of inflammation, but in some circumstances it contributes to tissue injury and organ failure. Previous work showed that p21-activated kinase (PAK) is a critical regulator of endothelial cell-cell junctions through effects on myosin light chain phosphorylation and cell contractility. We now show that blocking PAK function inhibits fluid leak in a mouse model of acute lung injury. In cultured endothelial cells, induction of myosin light chain phosphorylation by PAK is mediated by mitogen-activated protein kinase kinase and extracellular signal-regulated kinase (Erk). Erk in lipopolysaccharide (LPS)-treated mouse lung is activated in a PAK-dependent manner in several cell types, most prominently vascular endothelium. Activation of Erk requires the integrity of the complex between PAK, PIX, and GIT1. Several means of disrupting this complex inhibit stimulation of vascular permeability in vitro. A cell-permeant peptide that blocks binding of PAK to PIX inhibits LPS-induced fluid leak in the mouse lung injury model. We conclude that the PAK-PIX-GIT1 complex is critical for Erk-dependent myosin phosphorylation and vascular permeability.

Fatal Clostridium perfringens Meningitis Following Caudal Anesthesia in an Infant: A Case Report.

Caudal anesthesia is referred to as a simple and safe method to obtain analgesia in infants during various surgical procedures. Here, we present a fatal course of a premature infant that received caudal anesthesia for inguinal hernia repair. While anesthesia and surgery were uneventful, the child developed an acute bacterial meningoencephalitis within a few hours. Microbiology revealed the presence of Clostridium perfringens in the cerebrospinal fluid (CSF). The infant died 17 days after surgery. Preoperative screening for C. perfringens and particular caution in infants with intracerebral hemorrhages are discussed as potential factors to be considered when anesthesia is planned.