Common Variants of TLR1 Associate with Organ Dysfunction and Sustained Pro- Inflammatory Responses during Sepsis

Background: Toll-like receptors (TLRs) are critical components for host pathogen recognition and variants in genes participating in this response influence susceptibility to infections. Recently, TLR1 gene polymorphisms have been found correlated with whole blood hyper-inflammatory responses to pathogen-associated molecules and associated with sepsis-associated multiorgan dysfunction and acute lung injury (ALI). We examined the association of common variants of TLR1 gene with sepsis-derived complications in an independent study and with serum levels for four inflammatory biomarker among septic patients. Methodology/Principal Findings: Seven tagging single nucleotide polymorphisms of the TLR1 gene were genotyped in samples from a prospective multicenter case-only study of patients with severe sepsis admitted into a network of intensive care units followed for disease severity. Interleukin (IL)-1 b, IL-6, IL-10, and C-reactive protein (CRP) serum levels were measured at study entry, at 48 h and at 7th day. Alleles -7202G and 248Ser, and the 248Ser-602Ile haplotype were associated with circulatory dysfunction among severe septic patients (0.001<=p <= 0.022), and with reduced IL-10 (0.012<= p <=0.047) and elevated CRP (0.011<= p <=0.036) serum levels during the first week of sepsis development. Additionally, the -7202GG genotype was found to be associated with hospital mortality (p =0.017) and ALI (p =0.050) in a combined analysis with European Americans, suggesting common risk effects among studies Conclusions/Significance: These results partially replicate and extend previous findings, supporting that variants of TLR1 gene are determinants of severe complications during sepsis.

The caspase-3-p120-RasGAP module generates a NF-κB repressor in response to cellular stress.

The nuclear factor κB (NF-κB) transcription factor is a master regulator of inflammation. Short-term NF-κB activation is generally beneficial. However, sustained NF-κB might be detrimental, directly causing apoptosis of cells or leading to a persistent damaging inflammatory response. NF-κB activity in stressed cells needs therefore to be controlled for homeostasis maintenance. In mildly stressed cells, caspase-3 cleaves p120 RasGAP, also known as RASA1, into an N-terminal fragment, which we call fragment N. We show here that this fragment is a potent NF-κB inhibitor. Fragment N decreases the transcriptional activity of NF-κB by promoting its export from the nucleus. Cells unable to generate fragment N displayed increased NF-κB activation upon stress. Knock-in mice expressing an uncleavable p120 RasGAP mutant showed exaggerated NF-κB activation when their epidermis was treated with anthralin, a drug used for the treatment of psoriasis. Our study provides biochemical and genetic evidence of the importance of the caspase-3-p120-RasGAP stress-sensing module in the control of stress-induced NF-κB activation.

E2F1 mediates sustained lipogenesis and contributes to hepatic steatosis.

E2F transcription factors are known regulators of the cell cycle, proliferation, apoptosis, and differentiation. Here, we reveal that E2F1 plays an essential role in liver physiopathology through the regulation of glycolysis and lipogenesis. We demonstrate that E2F1 deficiency leads to a decrease in glycolysis and de novo synthesis of fatty acids in hepatocytes. We further demonstrate that E2F1 directly binds to the promoters of key lipogenic genes, including Fasn, but does not bind directly to genes encoding glycolysis pathway components, suggesting an indirect effect. In murine models, E2F1 expression and activity increased in response to feeding and upon insulin stimulation through canonical activation of the CDK4/pRB pathway. Moreover, E2F1 expression was increased in liver biopsies from obese, glucose-intolerant humans compared with biopsies from lean subjects. Finally, E2f1 deletion completely abrogated hepatic steatosis in different murine models of nonalcoholic fatty liver disease (NAFLD). In conclusion, our data demonstrate that E2F1 regulates lipid synthesis and glycolysis and thus contributes to the development of liver pathology.

Imbalance of naive and memory T lymphocytes with sustained high cellular activation during the first year of life from uninfected children born to HIV-1-infected mothers on HAART

The immune consequences of in utero HIV exposure to uninfected children whose mothers were submitted to highly active antiretroviral therapy (HAART) during gestation are not well defined. We evaluated 45 HIV-exposed uninfected (ENI) neonates and 45 healthy unexposed control (CT) neonates. All HIV-infected mothers received HAART during pregnancy, and the viral load at delivery was <50 copies/mL for 56.8%. Twenty-three ENI neonates were further evaluated after 12 months and compared to 23 unexposed healthy age-matched infants. Immunophenotyping was performed by flow cytometry in cord and peripheral blood. Cord blood lymphocyte numbers did not differ between groups. However, ENI neonates had a lower percentage of naive T cells than CT neonates (CD4+, 76.6 vs 83.1%, P < 0.001; CD8+, 70.9 vs 79.6%, P = 0.003) and higher percentages of central memory T cells than CT neonates (CD4+, 13.9 vs 8.7%, P < 0.001; CD8+, 8.6 vs 4.8%, P = 0.001). CD38 mean fluorescence intensity of T cells was higher in ENI neonates (CD4+, 62.2 vs 52.1, P = 0.007; CD8+, 47.7 vs 35.3, P < 0.001). At 12 months, ENI infants still had higher mean fluorescence intensity of CD38 on T cells (CD4+, 34.2 vs 23.3, P < 0.001; CD8+, 26.8 vs 19.4, P = 0.035). Despite effective maternal virologic control at delivery, HIV-exposed uninfected children were born with lower levels of naive T cells. Immune activation was present at birth and remained until at least 12 months of age, suggesting that in utero exposure to HIV causes subtle immune abnormalities.

Hind limb ischemic preconditioning induces an anti-inflammatory response by remote organs in rats

Ischemic preconditioning (IPC), a strategy used to attenuate ischemia-reperfusion injury, consists of brief ischemic periods, each followed by reperfusion, prior to a sustained ischemic insult. The purpose of the present study was to evaluate the local and systemic anti-inflammatory effects of hind limb IPC in male Wistar rat (200-250 g) models of acute inflammation. IPC was induced with right hind limb ischemia for 10 min by placing an elastic rubber band tourniquet on the proximal part of the limb followed by 30 min of reperfusion. Groups (N = 6-8) were submitted to right or left paw edema (PE) with carrageenan (100 µg) or Dextran (200 µg), hemorrhagic cystitis with ifosfamide (200 mg/kg, ip) or gastric injury (GI) with indomethacin (20 mg/kg, vo). Controls received similar treatments, without IPC (Sham-IPC). PE is reported as variation of paw volume (mL), vesical edema (VE) as vesical wet weight (mg), vascular permeability (VP) with Evans blue extravasation (µg), GI with the gastric lesion index (GLI; total length of all erosions, mm), and neutrophil migration (NM) from myeloperoxidase activity. The statistical significance (P < 0.05) was determined by ANOVA, followed by the Tukey test. Carrageenan or Dextran-induced PE and VP in either paw were reduced by IPC (42-58.7%). IPC inhibited VE (38.8%) and VP (54%) in ifosfamide-induced hemorrhagic cystitis. GI and NM induced by indomethacin were inhibited by IPC (GLI: 90.3%; NM: 64%). This study shows for the first time that IPC produces local and systemic anti-inflammatory effects in models of acute inflammation other than ischemia-reperfusion injury.

Effect of (+)-dehydrofukinone on GABAA receptors and stress response in fish model

(+)-Dehydrofukinone (DHF) is a major component of the essential oil of Nectandra grandiflora (Lauraceae), and exerts a depressant effect on the central nervous system of fish. However, the neuronal mechanism underlying DHF action remains unknown. This study aimed to investigate the action of DHF on GABAA receptors using a silver catfish (Rhamdia quelen) model. Additionally, we investigated the effect of DHF exposure on stress-induced cortisol modulation. Chemical identification was performed using gas chromatography-mass spectrometry and purity was evaluated using gas chromatography with a flame ionization detector. To an aquarium, we applied between 2.5 and 50 mg/L DHF diluted in ethanol, in combination with 42.7 mg/L diazepam. DHF within the range of 10-20 mg/L acted collaboratively in combination with diazepam, but the sedative action of DHF was reversed by 3 mg/L flumazenil. Additionally, fish exposed for 24 h to 2.5-20 mg/L DHF showed no side effects and there was sustained sedation during the first 12 h of drug exposure with 10-20 mg/L DHF. DHF pretreatment did not increase plasma cortisol levels in fish subjected to a stress protocol. Moreover, the stress-induced cortisol peak was absent following pretreatment with 20 mg/L DHF. DHF proved to be a relatively safe sedative or anesthetic, which interacts with GABAergic and cortisol pathways in fish.

Carbohydrate composition of ripe pineapple (cv. perola) and the glycemic response in humans

Brazil is the third largest producer of pineapple (Ananas comosus) and the market for fresh pineapple is sustained by the Hawaii and Perola cultivars. In this work the Perola cultivar was divided into three main parts, shell, core and pulp, for characterization. Moisture in the pulp was higher (between 10 and 15%) than in the shell and core. The amount of protein was higher in the core (35%) than in the pulp and shell. Perola contained relatively low concentrations of total ascorbic acid in the edible parts, although higher levels of ascorbic acid in the shell. Citric acid corresponded to almost 60% of the total organic acids. The total soluble sugars [~7-12% (FW)] were predominantly sucrose, fructose and glucose. The core had almost twice as much total sugar (12%) than the pulp (6.8%). The amount of insoluble dietary fiber was around 1%, and the soluble fiber was less than 0.1%. The pulp showed the highest concentration of polyphenols (0.49%) and antioxidant activity (33 µmol.g-1) out of the parts. The consumption of the pineapple pulp or core produced a high glycemic index (~93%), but considering the glycemic load, this fruit can be considered as low dietary.

Studies on the exaggerated inflammatory response caused by streptococcus suis at systemic and central nervous system levels

Streptococcus suis de type 2 est un microorganisme pathogène d’importance chez le porc. Il est la cause de différentes pathologies ayant comme caractéristique commune la méningite. C’est également un agent émergeant de zoonose : des cas cliniques humains ont récemment été rapportés en Asie. Cependant, la pathogénèse de S. suis n’est pas encore complètement élucidée. Jusqu’à présent, la réponse pro-inflammatoire initiée par S. suis n’a été étudiée qu’in vitro. L’étude du choc septique et de la méningite requiert toujours des modèles expérimentaux appropriés. Au cours de cette étude, nous avons développé un modèle in vivo d’infection chez la souris qui utilise la voie d’inoculation intra-péritonéale. Ce modèle a servi à l’étude de la réponse pro-inflammatoire associée à ce pathogène, tant au niveau systémique qu’au niveau du système nerveux central (SNC). Il nous a également permis de déterminer si la sensibilité aux infections à S. suis pouvait être influencée par des prédispositions génétiques de l’hôte. Le modèle d’infection par S. suis a été mis au point sur des souris de lignée CD1. Les résultats ont démontré une bactériémie élevée pendant les trois jours suivant l’infection. Celle-ci était accompagnée d’une libération rapide et importante de différentes cytokines pro-inflammatoires (TNF-α, IL-6, IL-12p40/p70, IFN-ɣ) et de chémokines (KC, MCP-1 and RANTES), qui ont entraîné un choc septique et la mort de 20 % des animaux. Ensuite, pour confirmer le rôle de l’inflammation sur la mortalité et pour déterminer si les caractéristiques génétiques de l’hôte pouvaient influencer la réponse inflammatoire et l’issue de la maladie, le modèle d’infection a été étendu à deux lignées murines consanguines différentes considérées comme résistante : la lignée C57BL/6 (B6), et sensible : la lignée A/J. Les résultats ont démontré une importante différence de sensibilité entre les souris A/J et les souris B6, avec un taux de mortalité atteignant 100 % à 20 h post-infection (p.i.) pour la première lignée et de seulement 16 % à 36 h p.i. pour la seconde. La quantité de bactéries dans le sang et dans les organes internes était similaire pour les deux lignées. Donc, tout comme dans la lignée CD1, la bactériémie ne semblait pas être liée à la mort des souris. La différence entre les taux de mortalité a été attribuée à un choc septique non contrôlé chez les souris A/J infectées par S. suis. Les souris A/J présentaient des taux exceptionnellement élevés de TNF-α, IL-12p40/p70, IL-1β and IFN- γ, significativement supérieurs à ceux retrouvés dans la lignée B6. Par contre, les niveaux de chémokines étaient similaires entre les lignées, ce qui suggère que leur influence est limitée dans le développement du choc septique dû à S. suis. Les souris B6 avaient une production plus élevée d’IL-10, une cytokine anti-inflammatoire, ce qui suppose que la cascade cytokinaire pro-inflammatoire était mieux contrôlée, entraînant un meilleur taux de survie. Le rôle bénéfique potentiel de l’IL-10 chez les souris infectées par S. suis a été confirmé par deux approches : d’une part en bloquant chez les souris B6 le récepteur cellulaire à l’IL-10 (IL-10R) par un anticorps monoclonal anti-IL-10R de souris et d’autre part en complémentant les souris A/J avec de l’IL-10 de souris recombinante. Les souris B6 ayant reçu le anticorps monoclonal anti-IL-10R avant d’être infectées par S. suis ont développé des signes cliniques aigus similaires à ceux observés chez les souris A/J, avec une mortalité rapide et élevée et des taux de TNF-α plus élevés que les souris infectées non traitées. Chez les souris A/J infectées par S. suis, le traitement avec l’IL-10 de souris recombinante a significativement retardé l’apparition du choc septique. Ces résultats montrent que la survie au choc septique dû à S. suis implique un contrôle très précis des mécanismes pro- et anti-inflammatoires et que la réponse anti-inflammatoire doit être activée simultanément ou très rapidement après le début de la réponse pro-inflammatoire. Grâce à ces expériences, nous avons donc fait un premier pas dans l’identification de gènes associés à la résistance envers S. suis chez l’hôte. Une des réussites les plus importantes du modèle d’infection de la souris décrit dans ce projet est le fait que les souris CD1 ayant survécu à la septicémie présentaient dès 4 jours p.i. des signes cliniques neurologiques clairs et un syndrome vestibulaire relativement similaires à ceux observés lors de méningite à S. suis chez le porc et chez l’homme. L’analyse par hybridation in situ combinée à de l’immunohistochimie des cerveaux des souris CD1 infectées a montré que la réponse inflammatoire du SNC débutait avec une augmentation significative de la transcription du Toll-like receptor (TLR)2 et du CD14 dans les microvaisseaux cérébraux et dans les plexus choroïdes, ce qui suggère que S. suis pourrait se servir de ces structures comme portes d’entrée vers le cerveau. Aussi, le NF-κB (suivi par le système rapporteur de l’activation transcriptionnelle de IκBα), le TNF-α, l’IL-1β et le MCP-1 ont été activés, principalement dans des cellules identifiées comme de la microglie et dans une moindre mesure comme des astrocytes. Cette activation a également été observée dans différentes structures du cerveau, principalement le cortex cérébral, le corps calleux, l’hippocampe, les plexus choroïdes, le thalamus, l’hypothalamus et les méninges. Partout, cette réaction pro-inflammatoire était accompagnée de zones extensives d’inflammation et de nécrose, de démyélinisation sévère et de la présence d’antigènes de S. suis dans la microglie. Nous avons mené ensuite des études in vitro pour mieux comprendre l’interaction entre S. suis et la microglie. Pour cela, nous avons infecté des cellules microgliales de souris avec la souche sauvage virulente (WT) de S. suis, ainsi qu’avec deux mutants isogéniques, un pour la capsule (CPS) et un autre pour la production d’hémolysine (suilysine). Nos résultats ont montré que la capsule était un important mécanisme de résistance à la phagocytose pour S. suis et qu’elle modulait la réponse inflammatoire, en dissimulant les composants pro-inflammatoires de la paroi bactérienne. Par contre, l’absence d’hémolysine, qui est un facteur cytotoxique potentiel, n’a pas eu d’impact majeur sur l’interaction de S. suis avec la microglie. Ces études sur les cellules microgliales ont permis de confirmer les résultats obtenus précédemment in vivo. La souche WT a induit une régulation à la hausse du TLR2 ainsi que la production de plusieurs médiateurs pro-inflammatoires, dont le TNF-α et le MCP-1. S. suis a induit la translocation du NF-kB. Cet effet était plus rapide dans les cellules stimulées par le mutant déficient en CPS, ce qui suggère que les composants de la paroi cellulaire représentent de puissants inducteurs du NF-kB. De plus, la souche S. suis WT a stimulé l’expression de la phosphotyrosine, de la PKC et de différentes cascades liées à l’enzyme mitogen-activated protein kinase (MAPK). Cependant, les cellules microgliales infectées par le mutant déficient en CPS ont montré des profils de phosphorylation plus forts et plus soutenus que celles infectées par le WT. Finalement, la capsule a aussi modulé l’expression de l’oxyde nitrique synthétase inductible (iNOS) induite par S. suis et par la production subséquente d’oxyde nitrique par la microglie. Ceci pourrait être lié in vivo à la neurotoxicité et à la vasodilatation. Nous pensons que ces résultats contribueront à une meilleure compréhension des mécanismes sous-tendant l’induction de l’inflammation par S. suis, ce qui devrait permettre, d’établir éventuellement des stratégies plus efficaces de lutte contre la septicémie et la méningite. Enfin, nous pensons que ce modèle expérimental d’infection chez la souris pourra être utilisé dans l’étude de la pathogénèse d’autres bactéries ayant le SNC pour cible.

Apatite-Polymer Composite Particles for Controlled Delivery of BMP-2: In Vitro Release and Cellular Response

Bone morphogenetic protein-2 (BMP-2) has the ability to induce osteoblast differentiation of undifferentiated cells, resulting in the healing of skeletal defects when delivered with a suitable carrier. We have applied a versatile delivery platform comprising a novel composite of two biomaterials with proven track records – apatite and poly(lactic-co-glycolic acid) (PLGA) – to the delivery of BMP-2. Sustained release of this growth factor was tuned with variables that affect polymer degradation and/or apatite dissolution, such as polymer molecular weight, polymer composition, apatite loading, and apatite particle size. The effect of released BMP-2 on C3H10T1/2 murine pluripotent mesenchymal cells was assessed by tracking the expression of osteoblastic makers, alkaline phosphatase (ALP) and osteocalcin. Release media collected over 100 days induced elevated ALP activity in C3H10T1/2 cells. The expression of osteocalcin was also upregulated significantly. These results demonstrated the potential of apatite-PLGA composite particles for releasing protein in bioactive form over extended periods of time.

Tropical and extratropical responses of the North Atlantic atmospheric circulation to a sustained weakening of the MOC

The tropospheric response to a forced shutdown of the North Atlantic Ocean’s meridional overturning circulation (MOC) is investigated in a coupled ocean–atmosphere GCM [the third climate configuration of the Met Office Unified Model (HadCM3)]. The strength of the boreal winter North Atlantic storm track is significantly increased and penetrates much farther into western Europe. The changes in the storm track are shown to be consistent with the changes in near-surface baroclinicity, which can be linked to changes in surface temperature gradients near regions of sea ice formation and in the open ocean. Changes in the SST of the tropical Atlantic are linked to a strengthening of the subtropical jet to the north, which, combined with the enhanced storm track, leads to a pronounced split in the jet structure over Europe. EOF analysis and stationary box indices methods are used to analyze changes to the North Atlantic Oscillation (NAO). There is no consistent signal of a change in the variability of the NAO, and while the changes in the mean flow project onto the positive NAO phase, they are significantly different from it. However, there is a clear eastward shift of the NAO pattern in the shutdown run, and this potentially has implications for ocean circulation and for the interpretation of proxy paleoclimate records.

Effects of volatile fatty acid supply on their absorption and on water kinetics in the rumen of sheep sustained by intragastric infusions

Three sheep fitted with a ruminal cannula and an abomasal catheter were used to study water kinetics and absorption of VFA infused continuously into the rumen. The effects of changing VFA concentrations in the rumen by shifting VFA infusion rates were investigated in an experiment with a 3 x 3 Latin square design. On experimental days, the animals received the basal infusion rate of VFA (271 mmol/h) during the first 2 h. Each animal then received VFA at a different rate (135, 394, or 511 mmol/h) for the next 7.5 h. Using soluble markers (polyethylene glycol and Cr-EDTA), ruminal volume, liquid outflow, apparent water absorption, and VFA absorption rates were estimated. There were no significant effects of VFA infusion rate on ruminal volume and water kinetics. As the VFA infusion rate was increased, VFA concentration and osmolality in the rumen were increased and pH was decreased. There was a biphasic response of liquid outflow to changes in the total VFA concentration in the rumen, as both variables increased together up to a total VFA concentration of 80.1 mM, whereas, beyond that concentration, liquid outflow remained stable at an average rate of 407 mL/h. There were significant linear (P = 0.003) and quadratic (P = 0.001) effects of VFA infusion rate on the VFA absorption rate, confirming that VFA absorption in the rumen is mainly a concentration-dependent process. The proportion of total VFA supplied that was absorbed in the rumen was 0.845 (0.822, 0.877, and 0.910 for acetate, propionate, and butyrate, respectively). The molar proportions of acetate, propionate, and butyrate absorbed were affected by the level of VFA infusion in the rumen, indicating that this level affected to a different extent the absorption of the different acids.

Use of water-miscible retinyl palmitate as markers of chylomicrons gives earlier peak response of plasma retinyl esters compared with oil-soluble retinyl palmitate

Delayed peak response of plasma retinyl esters (RE) relative to plasma triacylglycerols (TAG) and apolipoprotein (Apo) B-48 responses following a fat load supplemented with vitamin A raised doubts about the use of vitamin A to label dietary-derived lipids and lipoproteins. The present study compared the use of water-miscible and oil-soluble retinyl palmitate (RP) as markers of dietary-derived lipoproteins in healthy subjects along with the measurements of postprandial plasma TAG and ApoB-48 responses to investigate whether the delayed peak response observed was due to delayed intestinal output of RE from oil-based solutions. Nine healthy female subjects were given a standard test meal containing a dose (112 mg) of RP in either water-miscible or oil-soluble form in random order, on two separate occasions after a 12 h overnight fast. The results showed that the mean plasma RE concentrations reached a peak significantly later than mean plasma TAG and ApoB-48 concentrations when oil-soluble RP was consumed, whereas plasma RE peaked earlier relative to plasma TAG and ApoB-48 responses when water-miscible RP was used. The results suggested a more rapid absorption with a significantly higher and earlier peak response of plasma RE when water-miscible RP was consumed. This was in contrast to the delayed initial appearance and later sustained higher concentrations of plasma RE during the late postprandial period when oil-soluble RP was consumed. The RE response to the water-miscible RP showed better concordance with plasma TAG response than that of oil-soluble RP.

Sustained striatal activity predicts eudaimonic well-being and cortisol output

Eudaimonic well-being—a sense of purpose, meaning, and engagement with life—is protective against psychopathology and predicts physical health, including lower levels of the stress hormone cortisol. Although it has been suggested that the ability to engage the neural circuitry of reward may promote well-being and mediate the relationship between well-being and health, this hypothesis has remained untested. To test this hypothesis, we had participants view positive, neutral, and negative images while fMRI data were collected. Individuals with sustained activity in the striatum and dorsolateral prefrontal cortex to positive stimuli over the course of the scan session reported greater well-being and had lower cortisol output. This suggests that sustained engagement of reward circuitry in response to positive events underlies well-being and adaptive regulation of the hypothalamic-pituitary-adrenal axis.

Protease-activated receptor 2 (PAR2) protein and transient receptor potential vanilloid 4 (TRPV4) protein coupling is required for sustained inflammatory signaling

G protein-coupled receptors of nociceptive neurons can sensitize transient receptor potential (TRP) ion channels, which amplify neurogenic inflammation and pain. Protease-activated receptor 2 (PAR(2)), a receptor for inflammatory proteases, is a major mediator of neurogenic inflammation and pain. We investigated the signaling mechanisms by which PAR(2) regulates TRPV4 and determined the importance of tyrosine phosphorylation in this process. Human TRPV4 was expressed in HEK293 cells under control of a tetracycline-inducible promoter, allowing controlled and graded channel expression. In cells lacking TRPV4, the PAR(2) agonist stimulated a transient increase in [Ca(2+)](i). TRPV4 expression led to a markedly sustained increase in [Ca(2+)](i). Removal of extracellular Ca(2+) and treatment with the TRPV4 antagonists Ruthenium Red or HC067047 prevented the sustained response. Inhibitors of phospholipase A(2) and cytochrome P450 epoxygenase attenuated the sustained response, suggesting that PAR(2) generates arachidonic acid-derived lipid mediators, such as 5',6'-EET, that activate TRPV4. Src inhibitor 1 suppressed PAR(2)-induced activation of TRPV4, indicating the importance of tyrosine phosphorylation. The TRPV4 tyrosine mutants Y110F, Y805F, and Y110F/Y805F were expressed normally at the cell surface. However, PAR(2) was unable to activate TRPV4 with the Y110F mutation. TRPV4 antagonism suppressed PAR(2) signaling to primary nociceptive neurons, and TRPV4 deletion attenuated PAR(2)-stimulated neurogenic inflammation. Thus, PAR(2) activation generates a signal that induces sustained activation of TRPV4, which requires a key tyrosine residue (TRPV4-Tyr-110). This mechanism partly mediates the proinflammatory actions of PAR(2).

Antarctic ocean and sea ice response to ozone depletion: a two timescale problem

The response of the Southern Ocean to a repeating seasonal cycle of ozone loss is studied in two coupled climate models and found to comprise both fast and slow processes. The fast response is similar to the inter-annual signature of the Southern Annular Mode (SAM) on Sea Surface Temperature (SST), on to which the ozone-hole forcing projects in the summer. It comprises enhanced northward Ekman drift inducing negative summertime SST anomalies around Antarctica, earlier sea ice freeze-up the following winter, and northward expansion of the sea ice edge year-round. The enhanced northward Ekman drift, however, results in upwelling of warm waters from below the mixed layer in the region of seasonal sea ice. With sustained bursts of westerly winds induced by ozone-hole depletion, this warming from below eventually dominates over the cooling from anomalous Ekman drift. The resulting slow-timescale response (years to decades) leads to warming of SSTs around Antarctica and ultimately a reduction in sea-ice cover year-round. This two-timescale behavior - rapid cooling followed by slow but persistent warming - is found in the two coupled models analysed, one with an idealized geometry, the other a complex global climate model with realistic geometry. Processes that control the timescale of the transition from cooling to warming, and their uncertainties are described. Finally we discuss the implications of our results for rationalizing previous studies of the effect of the ozone-hole on SST and sea-ice extent. %Interannual variability in the Southern Annular Mode (SAM) and sea ice covary such that an increase and southward shift in the surface westerlies (a positive phase of the SAM) coincides with a cooling of Sea Surface Temperature (SST) around 70-50$^\circ$S and an expansion of the sea ice cover, as seen in observations and models alike. Yet, in modeling studies, the Southern Ocean warms and sea ice extent decreases in response to sustained, multi-decadal positive SAM-like wind anomalies driven by 20th century ozone depletion. Why does the Southern Ocean appear to have disparate responses to SAM-like variability on interannual and multidecadal timescales? Here it is demonstrated that the response of the Southern Ocean to ozone depletion has a fast and a slow response. The fast response is similar to the interannual variability signature of the SAM. It is dominated by an enhanced northward Ekman drift, which transports heat northward and causes negative SST anomalies in summertime, earlier sea ice freeze-up the following winter, and northward expansion of the sea ice edge year round. The enhanced northward Ekman drift causes a region of Ekman divergence around 70-50$^\circ$S, which results in upwelling of warmer waters from below the mixed layer. With sustained westerly wind enhancement in that latitudinal band, the warming due to the anomalous upwelling of warm waters eventually dominates over the cooling from the anomalous Ekman drift. Hence, the slow response ultimately results in a positive SST anomaly and a reduction in the sea ice cover year round. We demonstrate this behavior in two models: one with an idealized geometry and another, more detailed, global climate model. However, the models disagree on the timescale of transition from the fast (cooling) to the slow (warming) response. Processes that controls this transition and their uncertainties are discussed.