K2P2.1 is a regulator of inflammatory cell responses in idiopathic inflammatory myopathies

K2P2.1 (TREK1), a two-pore domain potassium channel, has emerged as regulator of leukocyte transmigration into the central nervous system. In the context of skeletal muscle, immune cell infiltration constitutes the pathogenic hallmark of idiopathic inflammatory myopathies (IIMs). However, the underlying mechanisms remain to be elucidated. In this study, we investigated the role of K2P2.1 in the autoimmune response of IIMs. We detected K2P2.1 expression in primary skeletal muscle and endothelial cells of murine and human origin. We observed an increased pro-inflammatory cell response, adhesion and transmigration by pharmacological blockade or genetic deletion of K2P2.1 in vitro and in in vivo myositis mouse models. Of note, our findings were not restricted to endothelial cells as skeletal muscle cells with impaired K2P2.1 function also demonstrated a strong pro-inflammatory response. Conversely, these features were abrogated by activation of K2P2.1 and improved the disease course of a myositis mouse model. In humans, K2P2.1 expression was diminished in IIM patients compared to non-diseased controls arguing for the translatability of our findings. In summary, K2P2.1 may regulate the inflammatory response of skeletal muscle. Further research is required to understand whether K2P2.1 could serve as novel therapeutic target.

Nuclease activity and protein A release of Staphylococcus aureus clinical isolates determine the virulence in a murine model of acute lung infection

Staphylococcus aureus is a common cause of hospital-acquired pneumonia associated with high mortality. Adequate clinical treatment is impeded by increasing occurrence of antibiotic resistances. Understanding the underlying mechanisms of its virulence during infections is a prerequisite to finding alternative treatments. Here, we demonstrated that an increased nuclease activity of a S. aureus isolate from a person with cystic fibrosis confers a growth advantage in a model of acute lung infection compared to the isogenic strain with low nuclease activity. Comparing these CF-isolates with a common MRSA-USA300 strain with similarly high nuclease activity but significantly elevated levels of Staphylococcal Protein A (SpA) revealed that infection with USA300 resulted in a significantly increased bacterial burden in a model of murine lung infection. Replenishment with the cell wall-bound SpA of S. aureus, which can also be secreted into the environment and binds to tumor necrosis factor receptor -1 (TNFR-1) to the CF-isolates abrogated these differences. In vitro experiments confirmed significant differences in spa-expression between USA300 compared to CF-isolates, thereby influencing TNFR-1 shedding, L-selectin shedding, and production of reactive oxygen species through activation of ADAM17.

The Fatal Circle of NETs and NET-Associated DAMPs Contributing to Organ Dysfunction

The innate immune system is the first line of defense against invading pathogens or sterile injuries. Pattern recognition receptors (PRR) sense molecules released from inflamed or damaged cells, or foreign molecules resulting from invading pathogens. PRRs can in turn induce inflammatory responses, comprising the generation of cytokines or chemokines, which further induce immune cell recruitment. Neutrophils represent an essential factor in the early immune response and fulfill numerous tasks to fight infection or heal injuries. The release of neutrophil extracellular traps (NETs) is part of it and was originally attributed to the capture and elimination of pathogens. In the last decade studies revealed a detrimental role of NETs during several diseases, often correlated with an exaggerated immune response. Overwhelming inflammation in single organs can induce remote organ damage, thereby further perpetuating release of inflammatory molecules. Here, we review recent findings regarding damage-associated molecular patterns (DAMPs) which are able to induce NET formation, as well as NET components known to act as DAMPs, generating a putative fatal circle of inflammation contributing to organ damage and sequentially occurring remote organ injury.

Resolving immune cells with patrolling behaviour by magnetic resonance time-lapse single cell tracking

BACKGROUND

Immune cells show distinct motion patterns that change upon inflammatory stimuli. Monocytes patrol the vasculature to screen for pathogens, thereby exerting an early task of innate immunity. Here, we aimed to non-invasively analyse single patrolling monocyte behaviour upon inflammatory stimuli.

METHODS

We used time-lapse Magnetic Resonance Imaging (MRI) of the murine brain to dynamically track single patrolling monocytes within the circulation distant to the actual site of inflammation in different inflammatory conditions, ranging from a subcutaneous pellet model to severe peritonitis and bacteraemia.

FINDINGS

Single patrolling immune cells with a velocity of <1 µm/s could be detected and followed dynamically using time-lapse MRI. We show, that due to local and systemic stimuli the slowly patrolling behaviour of monocytes is altered systemically and differs with type, duration and strength of the underlying stimulus.

INTERPRETATION

Using time-lapse MRI, it is now possible to investigate the behaviour of single circulating monocytes over the course of the systemic immune response. Monocyte patrolling behaviour is altered systemically even before the onset of clinical symptoms distant to and depending on the underlying inflammatory stimulus.

FUNDING

This study was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - CRC 1009 - 194468054 to AZ, CF and - CRC 1450 - 431460824 to MM, SN, HB, AZ, CF, the Joachim Herz Foundation (Add-on Fellowship for Interdisciplinary Life Sciences to MM), the Interdisciplinary Centre for Clinical Research (IZKF, core unit PIX) and the Medical Faculty of the University of Muenster (MEDK fellowship to FF and IF).

Impact of genetic potential for residual feed intake and diet fed during early- to mid-gestation in beef heifers on carcass characteristics and meat quality attributes of their castrated male offspring

Carcass attributes of steers were examined for influences of selection for residual feed intake (RFI), and exposure to different levels of prenatal nutrition. Heifers characterized for RFI corrected for backfat were mated to bulls with genetic potential for either High-RFI or Low-RFI, such that the progeny were expected to be H/H or L/L RFI (sire/dam). Pregnant heifers were assigned to a low diet (Ldiet; 0.40 kg/d ADG), or moderate diet (Mdiet; 0.57 kg/d ADG), from 30 to 150 days of gestation, after which all heifers were managed similarly. Steer offspring (n = 23) were also managed similarly until slaughter. Dressing percentage of steers from H-RFI dams/sires exposed to Ldiet during gestation was lower than all other groups (P = 0.02). Marbling was greater for steers from H-RFI parents, as was fat content of longissimus thoracis et lumborum and triceps brachii (P ≤ 0.02). Results suggest that parental selection for RFI and prenatal maternal diet can influence carcass characteristics of progeny.

Methane and carbon dioxide emissions and grazed forage intake from pregnant beef heifers previously classified for residual feed intake under drylot conditions

The objectives of this study were to quantify the effect of post-weaning residual feed intake (RFI) on subsequent grazed forage intake, methane (CH4), and carbon dioxide (CO2) emissions. Beef heifers classified for RFI adjusted for off-test backfat (RFIfat; 55 high and 56 low) at 9 mo of age were monitored 7 mo later for CH4 and CO2 emissions using the GreenFeed Emissions Monitoring system. About 56 of these heifers were also monitored as high and low RFIfat groups using open-path Fourier-transform infrared spectroscopy (OP-FTIR). Heifers were dosed with 1 kg of C32-labelled pellets once daily for 15 d, with twice daily fecal sampling the last 8 d to determine individual grazed forage intake using the n-alkane method. Low RFIfat pregnant heifers consumed less forage (10.25 vs. 10.81 kg dry matter d−1; P < 0.001), and emitted less daily CH4 (238.7 vs. 250.7 g d−1; P = 0.009) and CO2 (7578 vs. 8041 g d−1; P < 0.001) compared with high RFIfat animals. Results from the OP-FTIR further confirmed that low RFIfat heifers emitted 6.3% less (g d−1; P = 0.006) CH4 compared with their high RFIfat cohorts. Thus, selection for low RFIfat will decrease daily CH4 and CO2 emissions from beef cattle.

Phenotypic and genetic correlations between feeding behaviours and feed efficiency in crossbred beef replacement females

The objectives of this study were to identify the phenotypic and genetic relationships and heritability (h2) of feeding behaviours (FB) in replacement beef females. Between 2005 and 2017, heifers (N = 1394) were tested for feed intake using an electronic feed bunk system. The various FB were feeding duration (DUR; min d−1), head down time (HD; min d−1), feeding frequency (FREQ; events d−1), time-to-bunk (TTB; min). Dry matter intake (DMI; kg d−1), and residual feed intake adjusted for off-test ultrasound back fat thickness (RFIFAT) were also reported. The h2 estimates for DUR, HD, FREQ, TTB, DMI, and RFIFAT were 0.25 ± 0.05, 0.26 ± 0.06, 0.27 ± 0.05, 0.29 ± 0.06, 0.26 ± 0.05, and 0.40 ± 0.07, respectively. These are the first h2 to be presented for these FB among developing replacement heifers on a high-forage diet.

Methane and carbon dioxide emissions from yearling beef heifers and mature cows classified for residual feed intake under drylot conditions

This study quantified methane (CH4) and carbon dioxide (CO2) production from beef heifers and cows classified for residual feed intake adjusted for off-test backfat thickness (RFIfat) and reared in drylot during cold winter temperatures. Individual performance, daily feed intake, and RFIfat were obtained for 1068 crossbred and purebred yearling heifers (eight trials) as well as 176 crossbred mature cows (six trials) during the winters of 2015–2017 at two locations. A portion of these heifers (147 high RFIfat; 167 low RFIfat) and cows (69 high RFIfat; 70 low RFIfat) was monitored for enteric CH4 and CO2 emissions using the GreenFeed Emissions Monitoring (GEM) system (C-Lock Inc., Rapid City, SD, USA). Low RFIfat cattle consumed less feed [heifers, 7.80 vs. 8.48 kg dry matter (DM) d−1; cows, 11.64 vs. 13.16 kg DM d−1] and emitted less daily CH4 (2.5% for heifers; 3.7% for cows) and CO2 (1.4% for heifers; 3.4% for cows) compared with high RFIfat cattle. However, low RFIfat heifers and cows had higher CH4 (6.2% for heifers; 9.9% for cows) and CO2 yield (7.3% for heifers; 9.8% for cows) per kilogram DM intake compared with their high RFIfat pen mates. The GEM system performed at air temperatures between +20 and −30 °C. Feed intake of heifers and mature cows was differently affected by ambient temperature reduction between +20 and −15 °C and similarly increased their feed intake at temperatures below −15 °C. In conclusion, low RFIfat animals emit less daily enteric CH4 and CO2, due mainly to lower feed consumption at equal body weight, gain, and fatness.

How Do Students React When Their Performance Is Worse or Better Than Expected?

Abstract. We analyzed grade level and sex differences for changes in expectations and coping with expectation violations, based on the ViolEx model. A sample of 114 third to sixth graders (male, n = 44, 38.6 %; female, n = 70, 61.4 %) reported their expected achievement in trials with no feedback, worse-than-expected achievement feedback, and better-than-expected feedback. Expectations improved across the no-feedback and better-than-expected feedback trials, and deteriorated across worse-than-expected trials. While expectation change did not vary by grade level or sex, reported coping with expectation violation did vary, and pupils of younger years reported higher attempts to fulfill their expectations (assimilative behavior). Immunization against worse-than-expected feedback was associated with higher expectations in the negative-feedback condition, but protective effects of immunization were lost with an increasing number of expectation violations. In addition, higher willingness to reduce one’s expectations (accommodation) inhibited the update of expectations after receiving better-than-expected feedback. Conclusions for future research are drawn.

The ITIM Domain-Containing NK Receptor Ly49Q Impacts Pulmonary Infection by Mediating Neutrophil Functions

Pulmonary infection is a frequent pathology associated with excessive neutrophil infiltration. Ly49Q, an ITIM domain-bearing receptor expressed on different leukocytes, has been recently reported to impact neutrophil migration and polarization. Utilizing a murine model of Klebsiella pneumoniae-induced pulmonary infection in combination with additional in vivo and in vitro assays, we show that Ly49Q is critically involved in different steps of the leukocyte adhesion cascade. Ly49Q deficiency is associated with a reduced rolling velocity, impaired crawling capacity, and diminished transmigration. We show that overactivation of the neutrophil β₂ integrins Mac-1 and LFA-1 is responsible for increased adhesion and reduced neutrophil transmigration, resulting in a strongly impaired immune defense against pulmonary infection. Structure function analysis in vitro and in vivo demonstrated that different domains of Ly49Q are important for its function. In summary, Ly49Q regulates integrin activation and neutrophil recruitment and is required for an adequate immune response in pulmonary infection.

Skap2 is required for β2 integrin-mediated neutrophil recruitment and functions

Integrin activation is required for neutrophil functions. Impaired integrin activation on neutrophils is the hallmark of leukocyte adhesion deficiency (LAD) syndrome in humans, characterized by impaired leukocyte recruitment and recurrent infections. The Src kinase-associated phosphoprotein 2 (Skap2) is involved in integrin functions in different leukocyte subtypes. However, the role of Skap2 in β2 integrin activation and neutrophil recruitment is unknown. In this study, we demonstrate the crucial role of Skap2 in regulating actin polymerization and binding of talin-1 and kindlin-3 to the β2 integrin cytoplasmic domain, thereby being indispensable for β2 integrin activation and neutrophil recruitment. The direct interaction of Skap2 with the Wiskott-Aldrich syndrome protein via its SH3 domain is critical for integrin activation and neutrophil recruitment in vivo. Furthermore, Skap2 regulates integrin-mediated outside-in signaling events and neutrophil functions. Thus, Skap2 is essential to activate the β2 integrins, and loss of Skap2 function is sufficient to cause a LAD-like phenotype in mice.

Endothelial cell-derived CD95 ligand serves as a chemokine in induction of neutrophil slow rolling and adhesion

Integrin activation is crucial for the regulation of leukocyte rolling, adhesion and trans-vessel migration during inflammation and occurs by engagement of myeloid cells through factors presented by inflamed vessels. However, endothelial-dependent mechanisms of myeloid cell recruitment are not fully understood. Here we show using an autoperfused flow chamber assay of whole blood neutrophils and intravital microscopy of the inflamed cremaster muscle that CD95 mediates leukocyte slow rolling, adhesion and transmigration upon binding of CD95-ligand (CD95L) that is presented by endothelial cells. In myeloid cells, CD95 triggers activation of Syk-Btk/PLCγ2/Rap1 signaling that ultimately leads to integrin activation. Excitingly, CD95-deficient myeloid cells exhibit impaired bacterial clearance in an animal model of sepsis induced by cecal ligation and puncture (CLP). Our data identify the cellular and molecular mechanisms underlying the chemoattractant effect of endothelial cell-derived CD95L in induction of neutrophil recruitment and support the use of therapeutic inhibition of CD95’s activity in inflammatory diseases.

DOI:http://dx.doi.org/10.7554/eLife.18542.001

When tissues are damaged or infected, the body produces an inflammatory response. Neutrophils – a type of white blood cell – play an important part in this response. These cells normally circulate through the bloodstream, and are recruited to the inflamed site by chemical signals sent out by immune cells in the damaged tissue. This causes passing neutrophils to migrate through the wall of the blood vessel to gain access to the inflamed tissue.

The neutrophils go through a sequence of steps before they can pass through the blood vessel wall. After initially tethering to the cells that line the blood vessel, the neutrophils experience a period of “slow rolling” across the vessel lining, before tightly adhering to one of the cells.

In 2010, researchers determined that a protein on the neutrophil’s surface, known as CD95, helps the cell migrate through blood vessel walls. This protein interacts with a “ligand” molecule on the surface of the cells that line the blood vessel. However, it remains unclear whether CD95 and its ligand play a role in the steps that lead up to the neutrophils migrating through the blood vessel wall.

Gao et al. – who include researchers involved in the 2010 study – now show that activating CD95 in neutrophils also triggers the cell’s slow rolling and adhesion. Experiments performed on mouse cells and tissues showed that the cells that line the blood vessels present the CD95 ligand on their surfaces in order to activate CD95 in the neutrophils circulating in the bloodstream. This ultimately leads to neutrophil slow rolling and adhesion. Further experiments in mice showed that this ability of CD95 to recruit neutrophils to inflamed sites was crucial for clearing bacteria in cases of sepsis, where infection causes the immune system to damage the body’s own tissues.

Future studies could address whether inhibiting CD95's activity could help to treat diseases that feature uncontrolled white blood cell recruitment, including various cancers and autoimmune diseases.

DOI:http://dx.doi.org/10.7554/eLife.18542.002

Cross-Talk between Shp1 and PIPKIγ Controls Leukocyte Recruitment

Neutrophil recruitment to the site of inflammation plays a pivotal role in host defense. However, overwhelming activation and accumulation of neutrophils in the tissue may cause tissue damage and autoimmunity due to the release of cytokines, oxidants, and proteases. Neutrophil adhesion in acute inflammation is initiated by activation of αLβ2 (LFA-1), which can be induced by rolling on E-selectin (slowly) or by exposure to the chemokine CXCL1 (rapidly). Despite the clinical importance, cell-intrinsic molecular mechanisms of negative regulation of integrin adhesiveness and neutrophil recruitment are poorly understood. Mice deficient in the tyrosine phosphatase Src homology 2 domain-containing protein tyrosine phosphatase 1 (Shp1) show increased leukocyte adhesion, but the interpretation of these data is limited by the severe global phenotype of these mice. In this study, we used mice with global and myeloid-restricted deletion of Shp1 to study neutrophil arrest, adhesion, crawling, and transendothelial migration in vitro and in vivo. Shp1 deficiency results in increased neutrophil adhesion in vivo; however, neutrophil crawling, transmigration, and chemotaxis were reduced in these mice. Mechanistically, Shp1 binds and controls PIPKIγ activity and, thereby, modulates phosphatidylinositol (4,5)-bisphosphate levels and adhesion. Thus, Shp1 is involved in the deactivation of integrins and regulation of neutrophil recruitment into inflamed tissue.

Proteolytic Affinity Tag Cleavage

Here, we present protocols describing the use of the dipeptidyl-aminopeptidase-1 (DPP1, DAPase) exoprotease-based TAGZyme system and the endoprotease, Factor Xa. Both enable the recovery of proteins free of any amino acids encoded by the vector and/or protease recognition site. They also provide the possibility of removing the proteases from the preparation of the target protein by a simple subtractive chromatography step. TAGZyme enzymes contain an uncleavable His tag for removal by Immobilized Metal Ion Affinity Chromatography (IMAC). Factor Xa can be removed using Xa Removal Resin.

Purification of GST-Tagged Proteins

This protocol describes the purification of recombinant proteins fused to glutathione S-transferase (GST, GST-tagged proteins) by Glutathione Affinity purification. The GST tag frequently increases the solubility of the fused protein of interest and thus enables its purification and subsequent functional characterization. The GST-tagged protein specifically binds to glutathione immobilized to a matrix (e.g., agarose) and can be easily separated from a cell lysate by a bind-wash-elute procedure. GST-tagged proteins are often used to study protein-protein interactions, again making use of glutathione affinity in a procedure called a GST pull-down assay. The protocol is designed to process 200 ml of E. coli culture expressing intermediate to high amounts of a GST-tagged protein (~25 mg l(-1)). Depending on the expression rate or the available culture volume, the scale can be increased or decreased linearly. The protocol can also be used to purify GST-tagged proteins from other expression systems, such as insect or mammalian cells. Tips are provided to aid in modifying certain steps if proteins shall be recovered from alternative expression systems.

Expression and purification of membrane proteins

Approximately 30% of a genome encodes for membrane proteins. They are one of the most important classes of proteins in that they can receive, differentiate, and transmit intra- and intercellular signals. Some examples of classes of membrane proteins include cell-adhesion molecules, translocases, and receptors in signaling pathways. Defects in membrane proteins may be involved in a number of serious disorders such as neurodegenerative diseases (e.g., Alzheimer's) and diabetes. Furthermore, membrane proteins provide natural entry and anchoring points for the molecular agents of infectious diseases. Thus, membrane proteins constitute ~50% of known and novel drug targets. Progress in this area is slowed by the requirement to develop methods and procedures for expression and isolation that are tailored to characteristic properties of membrane proteins. A set of standard protocols for the isolation of the targets in quantities that allow for the characterization of their individual properties for further optimization is required. The standard protocols given below represent a workable starting point. If optimization of yields is desired, a variation of conditions as outlined in the theory section is recommended.

The PSGL-1-L-selectin signaling complex regulates neutrophil adhesion under flow

Neutrophils are recruited from the blood to sites of inflammation, where they contribute to immune defense but may also cause tissue damage. During inflammation, neutrophils roll along the microvascular endothelium before arresting and transmigrating. Arrest requires conformational activation of the integrin lymphocyte function-associated antigen 1 (LFA-1), which can be induced by selectin engagement. Here, we demonstrate that a subset of P-selectin glycoprotein ligand-1 (PSGL-1) molecules is constitutively associated with L-selectin. Although this association does not require the known lectin-like interaction between L-selectin and PSGL-1, the signaling output is dependent on this interaction and the cytoplasmic tail of L-selectin. The PSGL-1-L-selectin complex signals through Src family kinases, ITAM domain-containing adaptor proteins, and other kinases to ultimately result in LFA-1 activation. The PSGL-1-L-selectin complex-induced signaling effects on neutrophil slow rolling and recruitment in vivo demonstrate the functional importance of this pathway. We conclude that this is a signaling complex specialized for sensing adhesion under flow.

Regulation of PTEN activity by p38δ-PKD1 signaling in neutrophils confers inflammatory responses in the lung

Deletion of p38 MAP kinase p38 d results in decreased alveolar neutrophil accumulation and attenuation of acute lung injury through activation of protein kinase D1 and PTEN.

Despite their role in resolving inflammatory insults, neutrophils trigger inflammation-induced acute lung injury (ALI), culminating in acute respiratory distress syndrome (ARDS), a frequent complication with high mortality in humans. Molecular mechanisms underlying recruitment of neutrophils to sites of inflammation remain poorly understood. Here, we show that p38 MAP kinase p38δ is required for recruitment of neutrophils into inflammatory sites. Global and myeloid-restricted deletion of p38δ in mice results in decreased alveolar neutrophil accumulation and attenuation of ALI. p38δ counteracts the activity of its downstream target protein kinase D1 (PKD1) in neutrophils and myeloid-restricted inactivation of PKD1 leads to exacerbated lung inflammation. Importantly, p38δ and PKD1 conversely regulate PTEN activity in neutrophils, thereby controlling their extravasation and chemotaxis. PKD1 phosphorylates p85α to enhance its interaction with PTEN, leading to polarized PTEN activity, thereby regulating neutrophil migration. Thus, aberrant p38δ–PKD1 signaling in neutrophils may underlie development of ALI and life-threatening ARDS in humans.

The role of the tec kinase Bruton's tyrosine kinase (Btk) in leukocyte recruitment

Recruitment of leukocytes into inflamed tissue is a key component of the immune system. The activation of integrins on leukocytes is required for their recruitment into the inflamed tissue. Btk is a cytoplasmic nonreceptor tyrosine kinase belonging to the Tec-kinase family. It plays a key role in B-cell development and function, and recently published studies revealed important roles of Btk in myeloid cells. Btk might be activated through a variety of receptors leading to activation of integrins as the pivotal element in leukocyte recruitment. This review focuses on the role of Btk in B-lymphocyte homing and in neutrophil recruitment.

Severe impairment of leukocyte recruitment in ppGalNAcT-1-deficient mice

P-selectin glycoprotein ligand-1 plays an important role in leukocyte recruitment. Its binding affinity to selectins is modulated by posttranslational modifications. The polypeptide N-acetylgalactosamine transferase-1 (ppGalNAcT-1) initiates core-type protein O-glycosylation. To address whether the glycosylation of P-selectin glycoprotein ligand-1 by ppGalNAcT-1 is important for leukocyte recruitment in vivo, we investigated leukocyte recruitment in untreated and TNF-α-treated cremaster muscles comparing ppGalNAcT-1-deficient mice (Galnt1(-/-)) and wild-type mice. In untreated and TNF-α-treated Galnt1(-/-) mice, leukocyte rolling, adhesion, and transmigration were significantly reduced, with markedly increased rolling velocity compared with control mice. L-selectin-dependent leukocyte rolling was completely abolished in Galnt1(-/-) mice compared with wild-type mice. Thioglycollate-induced peritonitis experiments with chimeric mice revealed that hematopoietic ppGalNAcT-1 is important for leukocyte recruitment. These data show that the loss of ppGalNAcT-1 led to reduced leukocyte rolling and recruitment and increased rolling velocity, suggesting a predominant role for ppGalNAcT-1 in attaching functionally relevant O-linked glycans to selectin ligands.

Crucial role of SLP-76 and ADAP for neutrophil recruitment in mouse kidney ischemia-reperfusion injury

Leukocyte recruitment to the kidney during acute injury is mediated by E-selectin–mediated rolling and requires SLP-76 and the adaptor protein ADAP.

Neutrophils trigger inflammation-induced acute kidney injury (AKI), a frequent and potentially lethal occurrence in humans. Molecular mechanisms underlying neutrophil recruitment to sites of inflammation have proved elusive. In this study, we demonstrate that SLP-76 (SH2 domain–containing leukocyte phosphoprotein of 76 kD) and ADAP (adhesion and degranulation promoting adaptor protein) are involved in E-selectin–mediated integrin activation and slow leukocyte rolling, which promotes ischemia-reperfusion–induced AKI in mice. By using genetically engineered mice and transduced Slp76^−/− primary leukocytes, we demonstrate that ADAP as well as two N-terminal–located tyrosines and the SH2 domain of SLP-76 are required for downstream signaling and slow leukocyte rolling. The Tec family kinase Bruton tyrosine kinase is downstream of SLP-76 and, together with ADAP, regulates PI3Kγ (phosphoinositide 3-kinase–γ)- and PLCγ2 (phospholipase Cγ2)-dependent pathways. Blocking both pathways completely abolishes integrin affinity and avidity regulation. Thus, SLP-76 and ADAP are involved in E-selectin–mediated integrin activation and neutrophil recruitment to inflamed kidneys, which may underlie the development of life-threatening ischemia-reperfusion–induced AKI in humans.

Dissociation of VE-PTP from VE-cadherin is required for leukocyte extravasation and for VEGF-induced vascular permeability in vivo

Artificially stabilizing contacts between VE-cadherin and VE-PTP reduce vascular permeability and leukocyte extravasation in vivo.

We have recently shown that vascular endothelial protein tyrosine phosphatase (VE-PTP), an endothelial membrane protein, associates with VE-cadherin and is required for optimal VE-cadherin function and endothelial cell contact integrity. The dissociation of VE-PTP from VE-cadherin is triggered by vascular endothelial growth factor (VEGF) and by the binding of leukocytes to endothelial cells in vitro, suggesting that this dissociation is a prerequisite for the destabilization of endothelial cell contacts. Here, we show that VE-cadherin/VE-PTP dissociation also occurs in vivo in response to LPS stimulation of the lung or systemic VEGF stimulation. To show that this dissociation is indeed necessary in vivo for leukocyte extravasation and VEGF-induced vascular permeability, we generated knock-in mice expressing the fusion proteins VE-cadherin-FK 506 binding protein and VE-PTP-FRB* under the control of the endogenous VE-cadherin promoter, thus replacing endogenous VE-cadherin. The additional domains in both fusion proteins allow the heterodimeric complex to be stabilized by a chemical compound (rapalog). We found that intravenous application of the rapalog strongly inhibited VEGF-induced (skin) and LPS-induced (lung) vascular permeability and inhibited neutrophil extravasation in the IL-1β inflamed cremaster and the LPS-inflamed lung. We conclude that the dissociation of VE-PTP from VE-cadherin is indeed required in vivo for the opening of endothelial cell contacts during induction of vascular permeability and leukocyte extravasation.

Reprint of: Immobilized-Metal Affinity Chromatography (IMAC): A Review

This article reviews the development of immobilized-metal affinity chromatography (IMAC) and describes its most important applications. We provide an overview on the use of IMAC in protein fractionation and proteomics, in protein immobilization and detection, and on some special applications such as purification of immunoglobulins and the Chelex method. The most relevant application- purification of histidine-tagged recombinant proteins-will be reviewed in greater detail with focus of state-of-the-art materials, methods, and protocols, and the limitations of IMAC and recent advances to improve the technology and the methods will be described.

A high-density SNP genome-wide linkage scan in a large autism extended pedigree

We performed a high-density, single nucleotide polymorphism (SNP), genome-wide scan on a six-generation pedigree from Utah with seven affected males, diagnosed with autism spectrum disorder. Using a two-stage linkage design, we first performed a nonparametric analysis on the entire genome using a 10K SNP chip to identify potential regions of interest. To confirm potentially interesting regions, we eliminated SNPs in high linkage disequilibrium (LD) using a principal components analysis (PCA) method and repeated the linkage results. Three regions met genome-wide significance criteria after controlling for LD: 3q13.2-q13.31 (nonparametric linkage (NPL), 5.58), 3q26.31-q27.3 (NPL, 4.85) and 20q11.21-q13.12 (NPL, 5.56). Two regions met suggestive criteria for significance 7p14.1-p11.22 (NPL, 3.18) and 9p24.3 (NPL, 3.44). All five chromosomal regions are consistent with other published findings. Haplotype sharing results showed that five of the affected subjects shared more than a single chromosomal region of interest with other affected subjects. Although no common autism susceptibility genes were found for all seven autism cases, these results suggest that multiple genetic loci within these regions may contribute to the autism phenotype in this family, and further follow-up of these chromosomal regions is warranted.

Production and comprehensive quality control of recombinant human Interleukin-1beta: a case study for a process development strategy

We describe an efficient strategy to produce high-quality proteins by using a single large IMAC chromatography column and enzymatic His-tag removal via the TAGZyme system in pilot scale. Numerous quality assays demonstrated a high purity of the final product, the human cytokine Interleukin-1beta (IL-1beta). The protein preparation was apparently free of host cell proteins, endotoxins, protease, and aggregates. The N-terminal amino acid sequence of IL-1beta was in full agreement with the natural mature form of IL-1beta. The homogeneity of the product was further shown by X-ray structure determination which confirmed the previously solved structure of the protein. We propose the applied workflow as a strategy for industrial production of protein-based biopharmaceuticals.

The effects of limit feeding a high-energy barley-based diet to backgrounding cattle in western Canada

A series of three completely randomized design trials were conducted to compare the effects of a limit-fed high-grain diet relative with that of an ad libitum-fed high-forage diet on performance of growing cattle with similar total energy intakes. In trial 1, the ad libitum-fed high-forage diet was formulated to 1.58 and 0.98 Mcal NEm and NEg kg-1 DM. The high-grain diet was formulated to 1.91 Mcal NEm and 1.23 Mcal NEg kg-1 DM. Projected liveweight gains (1.22 kg d-1) and the amount of DM provided to the limit-fed high-grain cattle were based on the NEm and NEg equations for liveweight gain of large-frame steers (NRC 1984). A similar feeding regime was employed for trials 2 and 3; however, it was necessary to reduce energy intake equally after 30 d on feed to control weight gains. In trial 1, the limit-fed high-grain cattle had similar (P > 0.05) ADG and lower (P < 0.05) DMI than the ad libitum-fed high-forage cattle, leading to a 15.4% improvement (P < 0.05) in feed efficiency. Feed efficiency was improved (P < 0.05) by 16.9% in trial 2 and by 21.2% in trial 3 for the limit-fed high-grain cattle, primarily as a result of reduced (P < 0.05) DM intake and similar (P > 0.05) daily gains. Back fat accretion rates were greater (P < 0.05) in the limit-fed high-grain cattle, indicating differences in energy partitioning. The incidence of severe liver abscesses was greater (P < 0.05) for the limit-fed high-grain cattle in trial 2. These results indicate that limit feeding a high-grain diet to backgrounding cattle can be employed to target specific rates of gain and improve feed efficiency although managing acidosis to prevent liver abscesses may be an issue. Key words: Cattle, limit feeding, feed efficiency, liver abscesses

Rapid characterization of molecular chemistry, nutrient make-up and microlocation of internal seed tissue

Wheat differs from corn in biodegradation kinetics and fermentation characteristics. Wheat exhibits a relatively high rate (23% h(-1)) and extent (78% DM) of biodegradation, which can lead to metabolic problems such as acidosis and bloat in ruminants. The objective of this study was to rapidly characterize the molecular chemistry of the internal structure of wheat (cv. AC Barrie) and reveal both its structural chemical make-up and nutrient component matrix by analyzing the intensity and spatial distribution of molecular functional groups within the intact seed using advanced synchrotron-powered Fourier transform infrared (FTIR) microspectroscopy. The experiment was performed at the U2B station of the National Synchrotron Light Source at Brookhaven National Laboratory, New York, USA. The wheat tissue was imaged systematically from the pericarp, seed coat, aleurone layer and endosperm under the peaks at approximately 1732 (carbonyl C=O ester), 1515 (aromatic compound of lignin), 1650 (amide I), 1025 (non-structural CHO), 1550 (amide II), 1246 (cellulosic material), 1160, 1150, 1080, 930, 860 (all CHO), 3350 (OH and NH stretching), 2928 (CH(2) stretching band) and 2885 cm(-1) (CH(3) stretching band). Hierarchical cluster analysis and principal component analysis were applied to analyze the molecular FTIR spectra obtained from the different inherent structures within the intact wheat tissues. The results showed that, with synchrotron-powered FTIR microspectroscopy, images of the molecular chemistry of wheat could be generated at an ultra-spatial resolution. The features of aromatic lignin, structural and non-structural carbohydrates, as well as nutrient make-up and interactions in the seeds, could be revealed. Both principal component analysis and hierarchical cluster analysis methods are conclusive in showing that they can discriminate and classify the different inherent structures within the seed tissue. The wheat exhibited distinguishable differences in the structural and nutrient make-up among the pericarp, seed coat, aleurone layer and endosperm. Such information on the molecular chemistry can be used for grain-breeding programs for selecting a superior variety of wheat targeted for food and feed purposes and for predicting wheat quality and nutritive value in humans and animals. Thus advanced synchrotron-powered FTIR technology can provide a greater understanding of the plant-animal interface.

Tail behavior of the failure rate functions of mixtures

The tail behavior of the failure rate of mixtures of lifetime distributions is studied. A typical result is that if the failure rate of the strongest component of the mixture decreases to a limit, then the failure rate of the mixture decreases to the same limit. For a class of distributions containing the gamma distributions this result can be improved in the sense that the behavior of the failure rate of the mixture asymptotically mirrors that of the strongest component in whether it decreases or increases to a limit.

D-1 and D-2 receptor blockade have additive cataleptic effects in mice, but receptor effects may interact in opposite ways

The dopaminergic role of D-1 and D-2 receptors in catalepsy was evaluated using drugs with preferential receptor affinities. The D-1 antagonist, SCH 23390, caused distinct catalepsy in mice at 1, 2, and 10 mg/kg, IP, but not at two lower doses. The selective D-1 blocker, molindone, also caused catalepsy at 5 and 10 mg/kg; and blockade of both receptor types produced additive cataleptogenic effects. Apomorphine (4 mg/kg), which is an agonist for both receptors, potentiated SCH 23390-induced catalepsy much more than it did the catalepsy induced by molindone; the potentiation was produced by higher, not lower, doses of apomorphine. To determine if the apomorphine potentiation was mediated by D-1 or D-2 receptors, we tested selective agonists in mice that were concurrently injected with selective blockers. SCH 23390-induced catalepsy was potentiated by a large dose of the D-2 agonist, bromocriptine. The catalepsy of D-2 blockade with molindone was not potentiated by the D-1 agonist, SKF 38393, which slightly disrupted the catalepsy of D-2 blockade. We conclude that catalepsy is not a simple D-2 blockade phenomenon and that preferential antagonism of either receptor type can cause catalepsy. Catalepsy is most profound when both receptor types are blocked. Dopamine agonists, in large concentrations, are known to promote movements, and thus it is not surprising that they tend to disrupt catalepsy.(ABSTRACT TRUNCATED AT 250 WORDS)