IL-21 is produced by NKT cells and modulates NKT cell activation and cytokine production

The common gamma-chain cytokine, IL-21, is produced by CD4(+) T cells and mediates potent effects on a variety of immune cells including NK, T, and B cells. NKT cells express the receptor for IL-21; however, the effect of this cytokine on NKT cell function has not been studied. We show that IL-21 on its own enhances survival of NKT cells in vitro, and IL-21 increases the proliferation of NKT cells in combination with IL-2 or IL-15, and particularly with the CD1d-restricted glycosphingolipid Ag alpha-galactosylceramide. Similar to its effects on NK cells, IL-21 enhances NKT cell granular morphology, including granzyme B expression, and some inhibitory NK receptors, including Ly49C/I and CD94. IL-21 also enhanced NKT cell cytokine production in response to anti-CD3/CD28 in vitro. Furthermore, NKT cells may be subject to autocrine IL-21-mediated stimulation because they are potent producers of this cytokine following in vitro stimulation via CD3 and CD28, particularly in conjunction with IL-12 or following in vivo stimulation with alpha-galactosylceramide. Indeed, NKT cells produced much higher levels of IL-21 than conventional CD4 T cells in this assay. This study demonstrates that NKT cells are potentially a major source of IL-21, and that IL-21 may be an important factor in NKT cell-mediated immune regulation, both in its effects on NK, T, and B cells, as well as direct effects on NKT cells themselves. The influence of IL-21 in NKT cell-dependent models of tumor rejection, microbial clearance, autoimmunity, and allergy should be the subject of future investigations.     

Fluid shear regulates the kinetics and receptor specificity of Staphylococcus aureus binding to activated platelets

The interaction between surface components on the invading pathogen and host cells such as platelets plays a key role in the regulation of endovascular infections. However, the mechanisms mediating Staphylococcus aureus binding to platelets under shear remain largely unknown. This study was designed to investigate the kinetics and molecular requirements of platelet-S. aureus interactions in bulk suspensions subjected to a uniform shear field. Hydrodynamic shear-induced collisions augment platelet-S. aureus binding, which is further potentiated by platelet activation with stromal derived factor-1beta. Peak adhesion efficiency occurs at low shear (100 s(-1)) and decreases with increasing shear. The molecular interaction of platelet alpha(IIb)beta(3) with bacterial clumping factor A through fibrinogen bridging is necessary for stable bacterial binding to activated platelets under shear. Although this pathway is sufficient at low shear (相似文献   

Genome Analysis of the Anaerobic Thermohalophilic Bacterium Halothermothrix orenii

Halothermothirx orenii is a strictly anaerobic thermohalophilic bacterium isolated from sediment of a Tunisian salt lake. It belongs to the order Halanaerobiales in the phylum Firmicutes. The complete sequence revealed that the genome consists of one circular chromosome of 2578146 bps encoding 2451 predicted genes. This is the first genome sequence of an organism belonging to the Haloanaerobiales. Features of both Gram positive and Gram negative bacteria were identified with the presence of both a sporulating mechanism typical of Firmicutes and a characteristic Gram negative lipopolysaccharide being the most prominent. Protein sequence analyses and metabolic reconstruction reveal a unique combination of strategies for thermophilic and halophilic adaptation. H. orenii can serve as a model organism for the study of the evolution of the Gram negative phenotype as well as the adaptation under thermohalophilic conditions and the development of biotechnological applications under conditions that require high temperatures and high salt concentrations.     

ABA-dependent amine oxidases-derived H2O2 affects stomata conductance

Recently we showed that ABA is at least partly responsible for the induction of the polyamine exodus pathway in Vitis vinifera plants. Both sensitive and tolerant plants employ this pathway to orchestrate stress responses, differing between stress adaptation and programmed cell death. Herein we show that ABA is an upstream signal for the induction of the polyamine catabolic pathway in Vitis vinifera. Thus, amine oxidases are producing H₂O₂ which signals stomata closure. Moreover, the previously proposed model for the polyamine catabolic pathway is updated and discussed.Key words: plant growth, abscissic acid, polyamines, amine oxidases, signaling, oxidative stress, programmed cell deathWe have shown that tobacco salinity induces an exodus of the polyamine (PA) spermidine (Spd) into the apoplast where it is oxidized by polyamine oxidase (PAO) generating hydrogen peroxide (H₂O₂). Depending on the size of H₂O₂, it signals either tolerance-effector genes or the programmed cell death syndrome¹ (PCD). PAs are ubiquitous and biologically active molecules. In the recent years remarkable progress has been accomplished regarding the regulation of PAs biosynthesis and catalysis, not only under normal physiological but also under stress conditions.¹ The most studied PAs are the diamine Putrescine (Put) and its derivatives the triamine Spd and the tetramine spermine (Spm). They are present in the cells in soluble form (S), or conjugated either to low molecular weight compounds (soluble hydrolyzed form, SH) or to “macro” molecules or cell walls (pellet hydrolyzed form, PH). In higher plants, Put is synthesized either directly from ornithine via ornithine decarboxylase (ODC; EC 4.1.1.17) or indirectly from arginine via arginine decarboxylase (ADC; EC 4.1.1.19). Spd and Spm are synthesized via Spd synthase (EC 2.5.1.16, SPDS) and Spm synthase (EC 2.5.1.22, SPMS), respectively, by sequential addition of aminopropyl groups to Put, catalyzed by S-adenosyl-L-methionine decarboxylase (SAMDC; EC 4.1.1.50).^2,3 In plants, PAs are present in the cytoplasm, as well as in cellular organelles.⁴ Recently it was shown that during stress, they are secreted into the apoplast where they are oxidized by amine oxidases (AOs), such as diamine oxidase for Put (DAO, E.C. 1.4.3.6) and polyamine oxidase (PAO, E.C. 1.4.3.4) for Spd and Spm.^1,5,6 Oxidation of PAs generates, amongst other products, H₂O₂^1,7,8 which is involved in cell signaling processes coordinated by abscissic acid (ABA),⁹ but also acts as efficient oxidant and, at high concentration, orchestrates the PCD syndrome.^6,10 Two types of PA catabolism by PAO are known in plants: the terminal and the back-conversion pathways. The terminal one takes place in the apoplast, produces except H₂O₂, 1,3-diaminopropane and an aldehyde depending on the species. On the other hand, the back-conversion pathway is intracellular (cytoplasm and peroxisomes) resulting to the production of H₂O₂ and the sequential production of Put by Spm via Spd.^1,7 Now we have shown that PA exodus also occurs in Vitis vinifera and this phenomenon is at least partially induced by abscissic acid (ABA).¹¹ Thus, exogenous application of ABA results to PA exodus into the apoplast of grapevine. PA is oxidized by an AO resulting to production of H₂O₂. When the titer of H₂O₂ is below a threshold, expression of tolerance-effector genes is induced, while when it exceeds this threshold the programmed cell death (PCD) syndrome is induced.     

Genome sequence of the acid-tolerant Burkholderia sp. strain WSM2230 from Karijini National Park,Australia

Burkholderia sp. strain WSM2230 is an aerobic, motile, Gram-negative, non-spore-forming acid-tolerant rod isolated from acidic soil collected in 2001 from Karijini National Park, Western Australia, using Kennedia coccinea (Coral Vine) as a host. WSM2230 was initially effective in nitrogen-fixation with K. coccinea, but subsequently lost symbiotic competence. Here we describe the features of Burkholderia sp. strain WSM2230, together with genome sequence information and its annotation. The 6,309,801 bp high-quality-draft genome is arranged into 33 scaffolds of 33 contigs containing 5,590 protein-coding genes and 63 RNA-only encoding genes. The genome sequence of WSM2230 failed to identify nodulation genes and provides an explanation for the observed failure of the laboratory grown strain to nodulate. The genome of this strain is one of 100 sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.     

S-100 B Concentrations Are a Predictor of Decreased Survival in Patients with Major Trauma,Independently of Head Injury

Background

Major trauma remains one of the principle causes of disability and death throughout the world. There is currently no satisfactory risk assessment to predict mortality in patients with major trauma. The aim of our study is to examine whether S-100 B protein concentrations correlate with injury severity and survival in patients with major trauma, with special emphasis on patients without head injury.

Methods

Our retrospective data analysis comprised adult patients admitted to our emergency department between 1.12. 2008 and 31.12 2010 with a suspected major trauma. S-100 B concentrations were routinely assessed in major trauma patients.

Results

A total of 27.7% (378) of all patients had major trauma. The median ISS was 24.6 (SD 8.4); 16.6% (63/378) of the patients died. S-100 B concentrations correlated overall with the ISS (p<0.0001). Patients who died had significantly higher S-100 B concentrations than survivors (8.2 μg/l versus 2.2 μg/l, p<0.0001). Polytraumatised patients with and without head trauma did not differ significantly with respect to S-100 B concentration (3.2 μg/l (SD 5.3) versus 2.9 μg/l (SD 3.8), respectively, p = 0.63) or with respect to Injury Severity Score (24.8 (SD 8.6) versus 24.2 (SD 8.1), respectively, p = 0.56). S-100 B concentrations correlated negatively with survival (p<0.0001) in all patients and in both subgroups (p = 0.001 and p = 0.006, respectively)

Conclusions

S-100 concentrations on admission correlate positively with greater injury severity and decreased survival in major trauma patients, independently of the presence of a head injury. S-100 B protein levels at admission in patients with major trauma may therefore be used to assess outcome in all polytraumatised patients. These measurements should be subject to further evaluation.     

Complete genome sequence of Thermomonospora curvata type strain (B9)

Thermomonospora curvata Henssen 1957 is the type species of the genus Thermomonospora. This genus is of interest because members of this clade are sources of new antibiotics, enzymes, and products with pharmacological activity. In addition, members of this genus participate in the active degradation of cellulose. This is the first complete genome sequence of a member of the family Thermomonosporaceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 5,639,016 bp long genome with its 4,985 protein-coding and 76 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.