Angiopoietin-2 sensitizes endothelial cells to TNF-alpha and has a crucial role in the induction of inflammation

The angiopoietins Ang-1 and Ang-2 have been identified as ligands of the receptor tyrosine kinase Tie-2 (refs. 1,2). Paracrine Ang-1-mediated activation of Tie-2 acts as a regulator of vessel maturation and vascular quiescence. In turn, the antagonistic ligand Ang-2 acts by an autocrine mechanism and is stored in endothelial Weibel-Palade bodies from where it can be rapidly released upon stimulation. The rapid release of Ang-2 implies functions of the angiopoietin-Tie system beyond its established role during vascular morphogenesis as a regulator of rapid vascular responses. Here we show that mice deficient in Ang-2 (encoded by the gene Angpt2) cannot elicit an inflammatory response in thioglycollate-induced or Staphylococcus aureus-induced peritonitis, or in the dorsal skinfold chamber model. Recombinant Ang-2 restores the inflammation defect in Angpt2(-/-) mice. Intravital microscopy showed normal TNF-alpha-induced leukocyte rolling in the vasculature of Angpt2(-/-)mice, but rolling cells did not firmly adhere to activated endothelium. Cellular experiments showed that Ang-2 promotes adhesion by sensitizing endothelial cells toward TNF-alpha and modulating TNF-alpha-induced expression of endothelial cell adhesion molecules. Together, these findings identify Ang-2 as an autocrine regulator of endothelial cell inflammatory responses. Ang-2 thereby acts as a switch of vascular responsiveness exerting a permissive role for the activities of proinflammatory cytokines.     

Un biofacies à Trilobites Homalonotidae dans I'Ordovicien de la marge nord-gondwanienne: implications paléobiologiques et paléogéographiques

During the Llandeilo, the sandy lithological units which develop locally in the Armorican Massif, Spain and Morocco, are all characterized by similar trilobite associations in which endobenthic homalonotids. well adapted to shallow water and sandy substrate, are predominant. During the Llandeilo, on the northern Gondwanan margin, the wide geographical distribution of most of the trilobites, controlled by environmental factors, shows that the existence of a 'Proto-Tethys' ocean is unlikely. □ North Gondwana, Trilobita, Homalonotidae, Ordovician, Llandeilo. palaeoenvironment.     

Trilobites Calmoniidae de l'Ordovicien supérieur du Maroc et les origines de la Province Malvino-Cafre

A re-examination of the trilobite Baniaspis globosa Destombes (Phacopina) from the Ashgill of the Anti-Atlas (Morocco) shows that it has several derived characters which allow us to classify it in the family Calmoniidae. Calmoniids were characteristic members of the Malvino-Kaffric province during the Lower Devonian. Hence we regard the origins of this palaeogeographic province as located on the northern Gondwanan margin as early as Ashgill, or even Caradoc, times. We agree with those authors who have suggested that the trilobite associations present in the Anti-Atlas, the Montagne Noire (France) and Bohemia during the earlier Ordovician argue against the existence of a 'proto-Tethys' ocean.     

High local substrate availability stabilizes a cooperative trait

Cooperative behavior is widely spread in microbial populations. An example is the expression of an extracellular protease by the lactic acid bacterium Lactococcus lactis, which degrades milk proteins into free utilizable peptides that are essential to allow growth to high cell densities in milk. Cheating, protease-negative strains can invade the population and drive the protease-positive strain to extinction. By using multiple experimental approaches, as well as modeling population dynamics, we demonstrate that the persistence of the proteolytic trait is determined by the fraction of the generated peptides that can be captured by the cell before diffusing away from it. The mechanism described is likely to be relevant for the evolutionary stability of many extracellular substrate-degrading enzymes.     

The cytokines interleukin-1β and tumor necrosis factor-α stimulate CFTR-mediated fluid secretion by swine airway submucosal glands

The airway is kept sterile by an efficient innate defense mechanism. The cornerstone of airway defense is mucus containing diverse antimicrobial factors that kill or inactivate pathogens. Most of the mucus in the upper airways is secreted by airway submucosal glands. In patients with cystic fibrosis (CF), airway defense fails and the lungs are colonized by bacteria, usually Pseudomonas aeruginosa. Accumulating evidence suggests that airway submucosal glands contribute to CF pathogenesis by failing to respond appropriately to inhalation of bacteria. However, the regulation of submucosal glands by the innate immune system remains poorly understood. We studied the response of submucosal glands to the proinflammatory cytokines interleukin-1β and tumor necrosis factor-α. These are released into the airway submucosa in response to infection with the bacterium P. aeruginosa and are elevated in CF airways. Stimulation with IL-1β and TNF-α increased submucosal gland secretion in a concentration-dependent manner with a maximal secretion rate of 240 ± 20 and 190 ± 40 pl/min, respectively. The half maximal effective concentrations were 11 and 20 ng/ml, respectively. The cytokine effect was dependent on cAMP but was independent of cGMP, nitric oxide, Ca(2+), or p38 MAP kinase. Most importantly, IL-1β- and TNF-α-stimulated secretion was blocked by the CF transmembrane conductance regulator (CFTR) blocker, CFTRinh172 (100 μmol/l) but was not affected by the Ca(2+)-activated Cl(-) channel blocker, niflumic acid (1 μmol/l). The data suggest, that during bacterial infections and resulting release of proinflammatory cytokines, the glands are stimulated to secrete fluid, and this response is mediated by cAMP-activated CFTR, a process that would fail in patients with CF.     

Epizootiologic and ecologic investigations of European brown hares (Lepus europaeus) in selected populations from Schleswig-Holstein, Germany

From 1997-99 European brown hare (Lepus europaeus) population densities were estimated by spotlight surveys within different areas in Schleswig-Holstein, Germany. These areas showed a wide variation in local hare population densities. In addition, red fox (Vulpes vulpes) densities were estimated in 1997 by surveys of fox dens and litters. Sera of 321 hares (shot between 1998-2000) from four study areas were examined for antibodies against European brown hare syndrome virus (EBHSV) by enzyme linked immunosorbent assay (ELISA), Yersinia spp. (n = 299) and Francisella tularensis (n = 299) by western blotting, Brucella spp. by Rose Bengal test, and Toxoplasma gondii by Sabin-Feldman test (n = 318). Tissue samples comprising lung, liver, spleen, kidney, heart, and adrenal glands were collected for histopathology. Liver (n = 201) and spleen (n = 201) samples were processed for the detection of T. gondii-antigen in tissue sections and 321 liver and spleen samples were investigated for EBHSV-antigen by ELISA. Furthermore, 116 hares were examined macro- and microscopically for lungworms. Significant negative correlations between hare and fox densities were found in spring and autumn 1997. Antibodies against EBHSV were detected in 92 of 321 (29%), against Yersinia spp. in 163 of 299 (55%), and against T. gondii in 147 of 318 (46%) hares. We evaluated the potential influence of origin and hunting season on exposure rates of hares using logistic regression analysis. A strong association between hare densities and exposure rates was observed for various agents. One hundred and eight of 201 (57%) hares were positive for T. gondii-antigen. All sera were negative for antibodies against Brucella spp. and F. tularensis and all lung samples were negative for lungworms. In conclusion, variation in red fox densities may have an impact on the hare populations examined and the infectious diseases we studied seem to play a subordinate role in the dynamics of European brown hare populations from Schleswig-Holstein.     

Abrogation of CC chemokine receptor 9 ameliorates collagen-induced arthritis of mice

Introduction

Biological drugs are effective in patients with rheumatoid arthritis (RA), but increase severe infections. The CC chemokine receptor (CCR) 9 antagonist was effective for Crohn’s disease without critical adverse effects including infections in clinical trials. The present study was carried out to explore the pathogenic roles of chemokine (C-C motif) ligand (CCL) 25 and its receptor, CCR9, in autoimmune arthritis and to study if the CCR9 antagonist could be a new treatment for RA.

Methods

CCL25 and CCR9 expression was examined with immunohistochemistry and Western blotting. Concentration of interleukin (IL)-6, matrix metalloproteinase (MMP)-3 and tumor necrosis factor (TNF)-α was measured with enzyme-linked immunosorbent assays. Effects of abrogating CCR9 on collagen-induced arthritis (CIA) was evaluated using CCR9-deficient mice or the CCR9 antagonist, CCX8037. Fluorescence labeled-CD11b⁺ splenocytes from CIA mice were transferred to recipient CIA mice and those infiltrating into the synovial tissues of the recipient mice were counted.

Results

CCL25 and CCR9 proteins were found in the RA synovial tissues. CCR9 was expressed on macrophages, fibroblast-like synoviocytes (FLS) and dendritic cells in the synovial tissues. Stimulation with CCL25 increased IL-6 and MMP-3 production from RA FLS, and IL-6 and TNF-α production from peripheral blood monocytes. CIA was suppressed in CCR9-deficient mice. CCX8037 also inhibited CIA and the migration of transferred CD11b⁺ splenocytes into the synovial tissues.

Conclusions

The interaction between CCL25 and CCR9 may play important roles in cell infiltration into the RA synovial tissues and inflammatory mediator production. Blocking CCL25 or CCR9 may represent a novel safe therapy for RA.     

Delayed onset of midline netrin expression in Artemia franciscana coincides with commissural axon growth and provides evidence for homology of midline cells in distantly related arthropods

Although many similarities in arthropod central nervous systems (CNS) development exist, differences in midline cell formation and ventral nerve cord axonogenesis have been noted in arthropods. It is possible that changes in the expression of axon guidance molecules such as Netrin, which functions during commissural axon guidance in Drosophila and many other organisms, may parallel these differences. In this investigation, we analyze this hypothesis by examining Netrin accumulation during development of the brine shrimp Artemia franciscana, a branchiopod crustacean. An Artemia franciscana netrin (afrnet) orthologue was cloned. An antibody to the afrNet protein was generated and used to examine the pattern of afrNet accumulation during Artemia development. Despite differences between Drosophila and Artemia nerve cord development, examination of afrNet accumulation suggests that this protein functions to regulate commissure formation during Artemia CNS development. However, detection of afrNet at the midline and on commissural axons occurs at a relatively later time point in Artemia as compared with Drosophila. Detection of afrNet in a subset of midline cells that closely resemble Netrin-expressing cells at the Drosophila midline provides evidence for homology of midline cells in arthropods. Expression of Netrins in many other tissues is comparable, suggesting that Netrin proteins may play many conserved roles during arthropod development.     

Witterungseinflüsse auf die Pigmentbildung der Wiesenpflanzen und den Vitamin A-Gehalt der Milchfette

Zusammenfassung Der Carotin-, Chlorophyll a- und b-Gehalt (Pigment) in Gras von Weiden in 600 m Höhe am nördlichen Alpenrand (Südbayern) und der Vitamin A-Gehalt im Milchfett von Kühen im Stall nach Fütterung mit dem Gras wurde bestimmt und mit den Ergebnissen der meteorologischen Beobachtungen verglichen. Die Pigmentbildung in den Pflanzen wurde durch warme strahlungsreiche Witterung gefördert und durch starke TemperaturrückgÄnge und Bodenfröste gehemmt. Sie war ausserdem vom Standort abhÄngig: an S-HÄngen und auf Höhen in strahlungsgünstiger Lage war in sonnigen Perioden der Carotingehalt hoch, in Niederungen mit hÄufiger Nebelbildung, auf schattigen HÄngen und in Tallagen mit Kaltluft tief. In Witterungsperioden mit Bewölkung glich der höhere Anteil der Himmelsstrahlung die Expositionsunterschiede wieder aus. Extrem grosse Licht- und WÄrmeeinwirkungen sommerlicher Hitzeperioden hemmten die Pigmentbildung; der Milch Vitamin A-Gehalt zeigte gleichsinnige Schwankungen.

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Carotine, chlorophyll a and b (pigment) in some types of meadow grass (600 m) at the northern rim of the Alps and the vitamin A content in milk from cows in stables fed on this grass was determined and correlated with meteorological data. The pigment formation in the grass was enhanced by radiation-rich warm weather and was impeded by a fall in temperature and ground frosts. The carotine content was high in grass from south slopes and on hills in a favourable position for radiation during sunny periods and low in grass from low sites with cold air.During periods of cloudy weather the greater amount of sky radiation compensated for the smaller amount of exposure in the less favourable sites. Extremely strong effects of light and warmth during summer heat periods inhibited the pigment formation and there was also a similar change in the vitamin A content of the milk.

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Résumé La teneur en carotène et en chlorophylle a et b (pigment) de quelques herbes de prairies du nord des Alpes (Bavière) et la teneur en vitamine A du lait des vaches qui en furent nourries en étables ont été comparées à des données méteorologiques. La formation des pigments des herbages était accrue par un temps chaud et ensoleillé et était diminué par les chutes de température et le refroidissement du sol. Le taux de carotène des herbes des pentes exposées au sud et sur les collines était élevé durant les périodes de soleil, et bas dans les fonds de vallées exposées à l'air froid et sur les pentes à l'ombre. Pendant les périodes nuageuses, la plus grande luminosité du ciel compensait les différences dans 1'exposition.La formation de pigments était ralentie en été pendant les périodes de grandes chaleurs et d'irradiation extrèmes. Le contenu du lait en vitamine A montrait des variations dans le mÊme sens.