Interleukin-18: a therapeutic target in rheumatoid arthritis?

Interleukin 18 (IL-18), a member of the IL-1 superfamily of cytokines has been demonstrated to be an important mediator of both innate and adaptive immune responses. Several reports have implicated its role in the pathogenesis of rheumatoid arthritis (RA). Although biologic therapy is firmly established in the treatment of a number of inflammatory diseases including RA, partial and non-responder patients constitute residual unmet clinical need. The aim of this article is to briefly review the biology of, and experimental approaches to IL-18 neutralisation, together with speculation as to the relative merits of IL-18 as an alternative to existing targets.     

Sustained high levels of interleukin-6 contribute to the pathogenesis of enterovirus 71 in a neonate mouse model

Enterovirus 71 (EV71) is the major causative agent of hand, foot, and mouth disease (HFMD) in young children and has been consistently associated with the most severe complications of the disease, including central nervous system inflammation and pulmonary edema. Increasing frequency and amplitude of EV71 outbreaks have raised awareness and concerns worldwide. Previous reports proposed that overwhelming virus replication combined with the induction of massive proinflammatory cytokines is responsible for the pathogenicity of EV71. Specifically, elevated interleukin-6 (IL-6) levels were observed consistently in patients and strongly correlated with disease severity. In this study, we show in the neonate mouse model that sustained high levels of IL-6 produced upon EV71 infection lead to severe tissue damage and eventually death of the animals. Administration of anti-IL-6 neutralizing antibodies after the onset of the clinical symptoms successfully improved the survival rates and clinical scores of the infected hosts. Compared to untreated infected controls, anti-IL-6-treated mice displayed reduced tissue damage, absence of splenic atrophy, and increased immune cell activation. In addition, markedly elevated systemic levels of IL-10 were measured in the protected animals. Furthermore, there was no significant difference in virus titers between anti-IL-6-treated mice and untreated mice, indicating that the anti-IL-6 antibody-mediated protection is independent of the virus load. Our findings thus demonstrate that IL-6 plays a major role in EV71-induced immunopathogenesis. As there is still neither vaccine nor treatment available against EV71, anti-IL-6 antibody treatment represents a potential therapeutic approach to providing protection from the most severe complications of the disease.     

A pump-free tricellular blood–brain barrier on-a-chip model to understand barrier property and evaluate drug response

Disruption of the blood–brain barrier (BBB) leads to various neurovascular diseases. Development of therapeutics required to cross the BBB is difficult due to a lack of relevant in vitro models. We have developed a three-dimensional (3D) microfluidic BBB chip (BBBC) to study cell interactions in the brain microvasculature and to test drug candidates of neurovascular diseases. We isolated primary brain microvascular endothelial cells (ECs), pericytes, and astrocytes from neonatal rats and cocultured them in the BBBC. To mimic the 3D in vivo BBB structure, we used type I collagen hydrogel to pattern the microchannel via viscous finger patterning technique to create a matrix. ECs, astrocytes, and pericytes were cocultured in the collagen matrix. The fluid flow in the BBBC was controlled by a pump-free strategy utilizing gravity as driving force and resistance in a paper-based flow resistor. The primary cells cultured in the BBBC expressed high levels of junction proteins and formed a tight endothelial barrier layer. Addition of tumor necrosis factor alpha to recapitulate neuroinflammatory conditions compromised the BBB functionality. To mitigate the neuroinflammatory stimulus, we treated the BBB model with the glucocorticoid drug dexamethasone, and observed protection of the BBB. This BBBC represents a new simple, cost-effective, and scalable in vitro platform for validating therapeutic drugs targeting neuroinflammatory conditions.     

The Transmembrane Domains of Sindbis Virus Envelope Glycoproteins Induce Cell Death

Sindbis virus, the prototype alphavirus, kills cells by inducing apoptosis. To investigate potential mechanisms by which Sindbis virus induces apoptosis, we examined whether specific viral gene products were able to induce cell death. Genes encoding the three structural proteins—capsid, the precursor E1 (6K plus E1), and the precursor E2 (P62 or E3 plus E2)—were cotransfected with a β-galactosidase reporter plasmid in transient-transfection assays in rat prostate adenocarcinoma AT3 cells. Cell death, as determined by measuring the loss of blue cells, was observed in AT3 cells transfected with 6K plus E1 and with P62 but not in cells transfected with capsid. Deletion mutagenesis of P62 indicated that large regions of the cytoplasmic domain and extracellular domain were not essential for the induction of cell death. However, constructs containing the minimal E3 signal sequence fused to the E2 transmembrane domain and the minimal E3 signal sequence fused to the E1 transmembrane domain induced death as efficiently as full-length P62 and 6K plus E1, whereas no cell death was observed after transfection with a control construct containing the E3 signal sequence linked to the transmembrane domain of murine CD4. These data demonstrate that intracellular expression of the transmembrane domains of the Sindbis virus envelope glycoproteins can kill AT3 cells.     

A newly-developed community microarray resource for transcriptome profiling in Brassica species enables the confirmation of Brassica-specific expressed sequences

Background  

The Brassica species include an important group of crops and provide opportunities for studying the evolutionary consequences of polyploidy. They are related to Arabidopsis thaliana, for which the first complete plant genome sequence was obtained and their genomes show extensive, although imperfect, conserved synteny with that of A. thaliana. A large number of EST sequences, derived from a range of different Brassica species, are available in the public database, but no public microarray resource has so far been developed for these species.     

Heterochromatin loss as a determinant of progerin‐induced DNA damage in Hutchinson–Gilford Progeria

Hutchinson–Gilford progeria is a premature aging syndrome caused by a truncated form of lamin A called progerin. Progerin expression results in a variety of cellular defects including heterochromatin loss, DNA damage, impaired proliferation and premature senescence. It remains unclear how these different progerin‐induced phenotypes are temporally and mechanistically linked. To address these questions, we use a doxycycline‐inducible system to restrict progerin expression to different stages of the cell cycle. We find that progerin expression leads to rapid and widespread loss of heterochromatin in G1‐arrested cells, without causing DNA damage. In contrast, progerin triggers DNA damage exclusively during late stages of DNA replication, when heterochromatin is normally replicated, and preferentially in cells that have lost heterochromatin. Importantly, removal of progerin from G1‐arrested cells restores heterochromatin levels and results in no permanent proliferative impediment. Taken together, these results delineate the chain of events that starts with progerin expression and ultimately results in premature senescence. Moreover, they provide a proof of principle that removal of progerin from quiescent cells restores heterochromatin levels and their proliferative capacity to normal levels.     

In situ responses to elevated CO2 in tropical forest understorey plants

1. Plants growing in deep shade and high temperature, such as in the understorey of humid tropical forests, have been predicted to be particularly sensitive to rising atmospheric CO₂. We tested this hypothesis in five species whose microhabitat quantum flux density (QFD) was documented as a covariable. After 7 (tree seedlings of Tachigalia versicolor and Beilschmiedia pendula ) and 18 months (shrubs Piper cordulatum and Psychotria limonensis, and grass Pharus latifolius ) of elevated CO₂ treatment ( c. 700 μl litre^–1) under mean QFD of less than 11 μmol m^–2 s^–1, all species produced more biomass (25–76%) under elevated CO₂.
2. Total plant biomass tended to increase with microhabitat QFD (daytime means varying from 5 to 11μmol m^–2 s^–1) but the relative stimulation by elevated CO₂ was higher at low QFD except in Pharus .
3. Non-structural carbohydrate concentrations in leaves increased significantly in Pharus (+ 27%) and Tachigalia (+ 40%).
4. The data support the hypothesis that tropical plants growing near the photosynthetic light compensation point are responsive to elevated CO₂. An improved plant carbon balance in deep shade is likely to influence understorey plant recruitment and competition as atmospheric CO₂ continues to rise.     

The effects of sex hormones on immune function: a meta‐analysis

The effects of sex hormones on immune function have received much attention, especially following the proposal of the immunocompetence handicap hypothesis. Many studies, both experimental and correlational, have been conducted to test the relationship between immune function and the sex hormones testosterone in males and oestrogen in females. However, the results are mixed. We conducted four cross‐species meta‐analyses to investigate the relationship between sex hormones and immune function: (i) the effect of testosterone manipulation on immune function in males, (ii) the correlation between circulating testosterone level and immune function in males, (iii) the effect of oestrogen manipulation on immune function in females, and (iv) the correlation between circulating oestrogen level and immune function in females. The results from the experimental studies showed that testosterone had a medium‐sized immunosuppressive effect on immune function. The effect of oestrogen, on the other hand, depended on the immune measure used. Oestrogen suppressed cell‐mediated immune function while reducing parasite loads. The overall correlation (meta‐analytic relationship) between circulating sex hormone level and immune function was not statistically significant for either testosterone or oestrogen despite the power of meta‐analysis. These results suggest that correlational studies have limited value for testing the effects of sex hormones on immune function. We found little evidence of publication bias in the four data sets using indirect tests. There was a weak and positive relationship between year of publication and effect size for experimental studies of testosterone that became non‐significant after we controlled for castration and immune measure, suggesting that the temporal trend was due to changes in these moderators over time. Graphical analyses suggest that the temporal trend was due to an increased use of cytokine measures across time. We found substantial heterogeneity in effect sizes, except in correlational studies of testosterone, even after we accounted for the relevant random and fixed factors. In conclusion, our results provide good evidence that testosterone suppresses immune function and that the effect of oestrogen varies depending on the immune measure used.     

The role of survivin in angiogenesis during zebrafish embryonic development

Background  

Survivin is the smallest member of the inhibitor of apoptosis (IAP) gene family. Recently, the zebrafish survivin-1 gene has been cloned, showing remarkable sequence identity and similarity over the BIR domain compared with human and mouse survivin gene. Here we investigated the role of survivin in angiogenesis during zebrafish development. Morpholinos (MOs) targeting the 5' untranslated region (UTR) (Sur_UTR) and sequences flanking the initiation codon (Sur_ATG) of zebrafish survivin-1 gene were injected into embryos at 1–4 cell stage. Vasculature was examined by microangiography and GFP expression in Tg(fli1:EGFP) ^y1 embryos. Results: In embryos co-injected with Sur_UTR and Sur_ATG-MOs, vasculogenesis was intact but angiogenesis was markedly perturbed, especially in the inter-segmental vessels (ISV) and dorsal longitudinal anastomotic vessels (DLAV) of the trunk, the inner optic circle and optic veins of developing eyes and the sub-intestinal vessels. Apoptosis was increased, as shown by TUNEL staining and increase in caspase-3 activity. Efficacy of Sur_UTR and Sur_ATG-MOs was demonstrated by translation inhibition of co-injected 5'UTR survivin:GFP plasmids. The phenotypes could be recapitulated by splice-site MO targeting the exon2-intron junction of survivin gene and rescued by survivin mRNA. Injection of human vascular endothelial growth factor (VEGF) protein induced ectopic angiogenesis and increased survivin expression, whereas treatment with a VEGF receptor inhibitor markedly reduced angiogenesis and suppressed survivin expression. Conclusion: Survivin is involved in angiogenesis during zebrafish development and may be under VEGF regulation.     

Photosynthesis and Degree of Polymerization of Fructan during Reproductive Growth of Meadow Fescue at two Temperatures and two Photon Flux Densities

Accumulation of dry weight was measured in plant parts of meadowfescue (Festuca pratensis Huds.) that was grown at 16/11 °Cor 26/21 °C and with 20 or 60 nE cm^–2 s^–1 photosyntheticallyactive radiation. Plants reached anthesis about 3 weeks laterat 16/11 °C than at 26/21 °C and had then a higher proportionof dry weight in inflorescences and less in leaf blades. Growthtemperature had little effect on CO₂ exchange rate (CER) butplants grown at 60 nE cm^–2 s^–1 had higher CER thanthose grown at 20 nE cm^–2 s^–1. The concentration of water-soluble carbohydrates (WSC) at similargrowth stages was usually higher at 16/11°C than at 26/21°C.High radiation also led to higher WSC in stem and leaf tissue.Root tissue changed least and WSC did not exceed 10% of dryweight during the experiment. In all tissues, when WSC was high,the fructans were distributed into a group with a high degreeof polymerization (DP) and another with a low DP. The low DPgroup included sucrose, reducing sugars and fructans up to about20 units long. An apparent threshold concentration of WSC wasnecessary for synthesis of the high DP fructans. This concentrationwas near 12% for leaf tissue, about 6% for stem base tissue,and 2.5% for root tissue. The average apparent DP of the highDP fructan group was 43 to 50 for leaf tissue, 31 to 93 forstem base tissue, and 27 to 31 for roots. These characteristicsappeared to be mostly tissue dependent with less effect fromtemperature and radiation. Key words: Fructans, Meadow fescue, Environmental effects, Dry weight distribution