House dust mites activate nociceptor-mast cell clusters to drive type 2 skin inflammation.

Allergic skin diseases, such as atopic dermatitis, are clinically characterized by severe itching and type 2 immunity-associated hypersensitivity to widely distributed allergens, including those derived from house dust mites (HDMs). Here we found that HDMs with cysteine protease activity directly activated peptidergic nociceptors, which are neuropeptide-producing nociceptive sensory neurons that express the ion channel TRPV1 and Tac1, the gene encoding the precursor for the neuropeptide substance P. Intravital imaging and genetic approaches indicated that HDM-activated nociceptors drive the development of allergic skin inflammation by inducing the degranulation of mast cells contiguous to such nociceptors, through the release of substance P and the activation of the cationic molecule receptor MRGPRB2 on mast cells. These data indicate that, after exposure to HDM allergens, activation of TRPV1+Tac1+ nociceptor-MRGPRB2+ mast cell sensory clusters represents a key early event in the development of allergic skin reactions.

Alterations of Prostanoid Expression and Intestinal Epithelial Barrier Functions in Ileus.

INTRODUCTION: Intestinal manipulation (IM)-induced inflammation could contribute to postoperative ileus (POI) pathophysiology via the modulation of prostanoid pathways. To identify the prostanoids involved, we aimed to characterize the profile of prostanoids and their synthesis enzyme expression in a murine model of POI and to determine whether the altered prostanoids could contribute to POI. METHODS: Four or 14 h after IM in mice, gastrointestinal (GI) motility and intestinal epithelial barrier (IEB) permeability were assessed in vivo and ex vivo in Ussing chambers. Using high sensitivity liquid chromatography-tandem mass spectrometry, we characterized the tissue profile of polyunsaturated fatty acid metabolites in our experimental model. Finally, we evaluated in vivo the effects of the prostanoids studied upon IM-induced gut dysfunctions. RESULTS: We first showed that 14 h after IM was significantly faster than jejunal transit at 4 h post-IM, although it remained significantly increased compared to the control. In contrast, we showed that IM-induced inflammation increase in jejunum permeability was similar after four and 14 h. We next showed that expression of prostacyclin synthase and hemopoietic prostaglandin-D synthase mRNA and their products were significantly reduced 14 h after IM as compared to controls. Furthermore, 15-deoxy-delta 12,14-Prostaglandin J2 reduced the IM-induced inflammation increase in IEB permeability but had no effect on GI motility. In contrast, PGI2 increased IM-induced IEB permeability and motility dysfunctions. CONCLUSIONS: Arachidonic acid derivative contributes differentially to GI dysfunction in POI. The decrease of 15-deoxy-delta 12,14-Prostaglandin J2 levels induced by IM could contribute to impaired GI dysfunctions in POI and could be considered as putative therapeutic targets to restore barrier dysfunctions associated with POI.

Identification of bacterial lipopeptides as key players in IBS.

OBJECTIVES: Clinical studies revealed that early-life adverse events contribute to the development of IBS in adulthood. The aim of our study was to investigate the relationship between prenatal stress (PS), gut microbiota and visceral hypersensitivity with a focus on bacterial lipopeptides containing γ-aminobutyric acid (GABA). DESIGN: We developed a model of PS in mice and evaluated, in adult offspring, visceral hypersensitivity to colorectal distension (CRD), colon inflammation, barrier function and gut microbiota taxonomy. We quantified the production of lipopeptides containing GABA by mass spectrometry in a specific strain of bacteria decreased in PS, in PS mouse colons, and in faeces of patients with IBS and healthy volunteers (HVs). Finally, we assessed their effect on PS-induced visceral hypersensitivity. RESULTS: Prenatally stressed mice of both sexes presented visceral hypersensitivity, no overt colon inflammation or barrier dysfunction but a gut microbiota dysbiosis. The dysbiosis was distinguished by a decreased abundance of Ligilactobacillus murinus, in both sexes, inversely correlated with visceral hypersensitivity to CRD in mice. An isolate from this bacterial species produced several lipopeptides containing GABA including C14AsnGABA. Interestingly, intracolonic treatment with C14AsnGABA decreased the visceral sensitivity of PS mice to CRD. The concentration of C16LeuGABA, a lipopeptide which inhibited sensory neurons activation, was decreased in faeces of patients with IBS compared with HVs. CONCLUSION: PS impacts the gut microbiota composition and metabolic function in adulthood. The reduced capacity of the gut microbiota to produce GABA lipopeptides could be one of the mechanisms linking PS and visceral hypersensitivity in adulthood.

Dysosmobacter welbionis effects on glucose, lipid, and energy metabolism are associated with specific bioactive lipids.

The newly identified bacterium Dysosmobacter welbionis J115T improves host metabolism in high-fat diet (HFD)-fed mice. To investigate mechanisms, we used targeted lipidomics to identify and quantify bioactive lipids produced by the bacterium in the culture medium, the colon, the brown adipose tissue (BAT), and the blood of mice. In vitro, we compared the bioactive lipids produced by D. welbionis J115T versus the probiotic strain Escherichia coli Nissle 1917. D. welbionis J115T administration reduced body weight, fat mass gain, and improved glucose tolerance and insulin resistance in HFD-fed mice. In vitro, 19 bioactive lipids were highly produced by D. welbionis J115T as compared to Escherichia coli Nissle 1917. In the plasma, 13 lipids were significantly changed by the bacteria. C18-3OH was highly present at the level of the bacteria, but decreased by HFD treatment in the plasma and normalized in D. welbionis J115T-treated mice. The metabolic effects were associated with a lower whitening of the BAT. In the BAT, HFD decreased the 15-deoxy-Δ12,14-prostaglandin J2, a peroxisome proliferator-activated receptor (PPAR-γ) agonist increased by 700% in treated mice as compared to HFD-fed mice. Several genes controlled by PPAR-γ were upregulated in the BAT. In the colon, HFD-fed mice had a 60% decrease of resolvin D5, whereas D. welbionis J115T-treated mice exhibited a 660% increase as compared to HFD-fed mice. In a preliminary experiment, we found that D. welbionis J115T improves colitis. In conclusion, D. welbionis J115T influences host metabolism together with several bioactive lipids known as PPAR-γ agonists.

Uropathogenic E. coli induces DNA damage in the bladder.

Urinary tract infections (UTIs) are among the most common outpatient infections, with a lifetime incidence of around 60% in women. We analysed urine samples from 223 patients with community-acquired UTIs and report the presence of the cleavage product released during the synthesis of colibactin, a bacterial genotoxin, in 55 of the samples examined. Uropathogenic Escherichia coli strains isolated from these patients, as well as the archetypal E. coli strain UTI89, were found to produce colibactin. In a murine model of UTI, the machinery producing colibactin was expressed during the early hours of the infection, when intracellular bacterial communities form. We observed extensive DNA damage both in umbrella and bladder progenitor cells. To the best of our knowledge this is the first report of colibactin production in UTIs in humans and its genotoxicity in bladder cells.

Prenatal stress induces changes in PAR2- and M3-dependent regulation of colon primitive cells.

Prenatal stress is associated with a high risk of developing adult intestinal pathologies, such as irritable bowel syndrome, chronic inflammation, and cancer. Although epithelial stem cells and progenitors have been implicated in intestinal pathophysiology, how prenatal stress could impact their functions is still unknown. We have investigated the proliferative and differentiation capacities of primitive cells using epithelial crypts isolated from colons of adult male and female mice whose mothers have been stressed during late gestation. Our results show that stem cell/progenitor proliferation and differentiation in vitro are negatively impacted by prenatal stress in male progeny. This is promoted by a reinforcement of the negative proliferative/differentiation control by the protease-activated receptor 2 (PAR2) and the muscarinic receptor 3 (M3), two G protein-coupled receptors present in the crypt. Conversely, prenatal stress does not change in vitro proliferation of colon primitive cells in female progeny. Importantly, this maintenance is associated with a functional switch in the M3 negative control of colonoid growth, becoming proliferative after prenatal stress. In addition, the proliferative role of PAR2 specific to females is maintained under prenatal stress, even though PAR2-targeted stress signals Dusp6 and activated GSK3ß are increased, reaching the levels of males. An epithelial serine protease could play a critical role in the activation of the survival kinase GSK3ß in colonoids from prenatally stressed female progeny. Altogether, our results show that following prenatal stress, colon primitive cells cope with stress through sexually dimorphic mechanisms that could pave the way to dysregulated crypt regeneration and intestinal pathologies.NEW & NOTEWORTHY Primitive cells isolated from mouse colon following prenatal stress and exposed to additional stress conditions such as in vitro culture, present sexually dimorphic mechanisms based on PAR2- and M3-dependent regulation of proliferation and differentiation. Whereas prenatal stress reinforces the physiological negative control exerted by PAR2 and M3 in crypts from males, in females, it induces a switch in M3- and PAR2-dependent regulation leading to a resistant and proliferative phenotype of progenitor.

Delta opioid receptors on nociceptive sensory neurons mediate peripheral endogenous analgesia in colitis.

BACKGROUND: Inflammatory visceral pain is endogenously controlled by enkephalins locally released by mucosal CD4+ T lymphocytes in mice. The present study aimed at identifying opioid receptor(s) expressed on nociceptive sensory nerves involved in this peripheral opioid-mediated analgesia. METHODS: The peripheral analgesia associated with the accumulation of CD4+ T lymphocytes within the inflamed colonic mucosa was assessed in conditional knockout mice specifically deleted for either of the two opioid receptors for enkephalins (i.e., µ (MOR) and δ (DOR) receptors) in Nav1.8-expressing sensory neurons in the dextran sulfate sodium (DSS)-induced colitis model. RESULTS: Endogenous analgesia is lost in conditional knockout mice for DOR, but not MOR at the later phase of the DSS-induced colitis. The absence of either of the opioid receptors on sensory nerves had no impact on both the colitis severity and the rate of T lymphocytes infiltrating the inflamed colonic mucosa. CONCLUSION: The key role of DOR on primary afferents in relieving intestinal inflammatory pain opens new therapeutic opportunities for peripherally restricted DOR analgesics to avoid most of the side effects associated with MOR-targeting drugs used in intestinal disorders.

Identification of bacterial lipo-amino acids: origin of regenerated fatty acid carboxylate from dissociation of lipo-glutamate anion.

The identification of bacterial metabolites produced by the microbiota is a key point to understand its role in human health. Among them, lipo-amino acids (LpAA), which are able to cross the epithelial barrier and to act on the host, are poorly identified. Structural elucidation of few of them was performed by high-resolution tandem mass spectrometry based on electrospray combined with selective ion dissociations reach by collision-induced dissociation (CID). The negative ions were used for their advantages of yielding only few fragment ions sufficient to specify each part of LpAA with sensitivity. To find specific processes that help structural assignment, the negative ion dissociations have been scrutinized for an LpAA: the N-palmitoyl acyl group linked to glutamic acid (C16Glu). The singular behavior of [C16Glu-H]¯ towards CID showed tenth product ions, eight were described by expected fragment ions. In contrast, instead of the expected product ions due to CONH-CH bond cleavage, an abundant complementary dehydrated glutamic acid and fatty acid anion pair were observed. Specific to glutamic moiety, they were formed by a stepwise dissociation via molecular isomerization through ion-dipole formation prior to dissociation. This complex dissociated by partner splitting either directly or after inter-partner proton transfer. By this pathway, surprising regeneration of deprotonated fatty acid takes place. Such regeneration is comparable to that occurred from dissociation to peptides containing acid amino-acid. Modeling allow to confirm the proposed mechanisms explaining the unexpected behavior of this glutamate conjugate.

Bacteria-derived long chain fatty acid exhibits anti-inflammatory properties in colitis.

OBJECTIVE: Data from clinical research suggest that certain probiotic bacterial strains have the potential to modulate colonic inflammation. Nonetheless, these data differ between studies due to the probiotic bacterial strains used and the poor knowledge of their mechanisms of action. DESIGN: By mass-spectrometry, we identified and quantified free long chain fatty acids (LCFAs) in probiotics and assessed the effect of one of them in mouse colitis. RESULTS: Among all the LCFAs quantified by mass spectrometry in Escherichia coli Nissle 1917 (EcN), a probiotic used for the treatment of multiple intestinal disorders, the concentration of 3-hydroxyoctadecaenoic acid (C18-3OH) was increased in EcN compared with other E. coli strains tested. Oral administration of C18-3OH decreased colitis induced by dextran sulfate sodium in mice. To determine whether other bacteria composing the microbiota are able to produce C18-3OH, we targeted the gut microbiota of mice with prebiotic fructooligosaccharides (FOS). The anti-inflammatory properties of FOS were associated with an increase in colonic C18-3OH concentration. Microbiota analyses revealed that the concentration of C18-3OH was correlated with an increase in the abundance in Allobaculum, Holdemanella and Parabacteroides. In culture, Holdemanella biformis produced high concentration of C18-3OH. Finally, using TR-FRET binding assay and gene expression analysis, we demonstrated that the C18-3OH is an agonist of peroxisome proliferator activated receptor gamma. CONCLUSION: The production of C18-3OH by bacteria could be one of the mechanisms implicated in the anti-inflammatory properties of probiotics. The production of LCFA-3OH by bacteria could be implicated in the microbiota/host interactions.

Peripheral Opioid Receptor Blockade Enhances Epithelial Damage in Piroxicam-Accelerated Colitis in IL-10-Deficient Mice.

Mucosal CD4+ T lymphocytes display a potent opioid-mediated analgesic activity in interleukin (IL)-10 knockout mouse model of inflammatory bowel diseases (IBD). Considering that endogenous opioids may also exhibit anti-inflammatory activities in the periphery, we examined the consequences of a peripheral opioid receptor blockade by naloxone-methiodide, a general opioid receptor antagonist unable to cross the blood-brain barrier, on the development of piroxicam-accelerated colitis in IL-10-deficient (IL-10-/-) mice. Here, we show that IL-10-deficient mice treated with piroxicam exhibited significant alterations of the intestinal barrier function, including permeability, inflammation-related bioactive lipid mediators, and mucosal CD4+ T lymphocyte subsets. Opioid receptor antagonization in the periphery had virtually no effect on colitis severity but significantly worsened epithelial cell apoptosis and intestinal permeability. Thus, although the endogenous opioid tone is not sufficient to reduce the severity of colitis significantly, it substantially contributes to the protection of the physical integrity of the epithelial barrier.

Rapid and Efficient Production of Human Functional Mast Cells through a Three-Dimensional Culture of Adipose Tissue-Derived Stromal Vascular Cells.

Mast cells (MC) are innate immune cells involved in many physiological and pathological processes. However, studies of MC function and biology are hampered by the difficulties to obtain human primary MC. To solve this problem, we established a new method to produce easily and rapidly high numbers of MC for in vitro studies using human adipose tissue, which is an abundant and easy access tissue. Stromal vascular fraction of adipose tissue, obtained from human abdominal dermolipectomy, was cultured as spheroids in serum free medium supplemented in stem cell factor. Using this method, we generated, within 3 wk, a highly pure population of connective tissue-type MC expressing MC typical peptidases (tryptase, chymase, and carboxypeptidase-A3) with a yield increasing over time. Stem cell factor was required for this culture, but unlike MC derived from CD34+ cells, this culture did not depend on IL-3 and -6. MC obtained with this method degranulated following FcεRI cross-linking or stimulation by C5a, compound 48/80, and substance P. Interestingly, activation by anti-IgE of both white adipose tissue-MC and MC obtained from peripheral blood-derived CD34+ pluripotent progenitor cells induced the production of PGs as well as proinflammatory cytokines (TNF-α, Il-6, and GM-CSF). In conclusion, we developed a new time saving and reproducible method to produce highly pure and functional human MC in 3 wk from human adipose tissue.

Polyunsaturated fatty acid metabolites: biosynthesis in Leishmania and role in parasite/host interaction.

Inside the human host, Leishmania infection starts with phagocytosis of infective promastigotes by macrophages. In order to survive, Leishmania has developed several strategies to manipulate macrophage functions. Among these strategies, Leishmania as a source of bioactive lipids has been poorly explored. Herein, we assessed the biosynthesis of polyunsaturated fatty acid metabolites by infective and noninfective stages of Leishmania and further explored the role of these metabolites in macrophage polarization. The concentration of docosahexaenoic acid metabolites, precursors of proresolving lipid mediators, was increased in the infective stage of the parasite compared with the noninfective stage, and cytochrome P450-like proteins were shown to be implicated in the biosynthesis of these metabolites. The treatment of macrophages with lipids extracted from the infective forms of the parasite led to M2 macrophage polarization and blocked the differentiation into the M1 phenotype induced by IFN-γ. In conclusion, Leishmania polyunsaturated fatty acid metabolites, produced by cytochrome P450-like protein activity, are implicated in parasite/host interactions by promoting the polarization of macrophages into a proresolving M2 phenotype.

PPARγ Is Activated during Congenital Cytomegalovirus Infection and Inhibits Neuronogenesis from Human Neural Stem Cells.

Congenital infection by human cytomegalovirus (HCMV) is a leading cause of permanent sequelae of the central nervous system, including sensorineural deafness, cerebral palsies or devastating neurodevelopmental abnormalities (0.1% of all births). To gain insight on the impact of HCMV on neuronal development, we used both neural stem cells from human embryonic stem cells (NSC) and brain sections from infected fetuses and investigated the outcomes of infection on Peroxisome Proliferator-Activated Receptor gamma (PPARγ), a transcription factor critical in the developing brain. We observed that HCMV infection dramatically impaired the rate of neuronogenesis and strongly increased PPARγ levels and activity. Consistent with these findings, levels of 9-hydroxyoctadecadienoic acid (9-HODE), a known PPARγ agonist, were significantly increased in infected NSCs. Likewise, exposure of uninfected NSCs to 9-HODE recapitulated the effect of infection on PPARγ activity. It also increased the rate of cells expressing the IE antigen in HCMV-infected NSCs. Further, we demonstrated that (1) pharmacological activation of ectopically expressed PPARγ was sufficient to induce impaired neuronogenesis of uninfected NSCs, (2) treatment of uninfected NSCs with 9-HODE impaired NSC differentiation and (3) treatment of HCMV-infected NSCs with the PPARγ inhibitor T0070907 restored a normal rate of differentiation. The role of PPARγ in the disease phenotype was strongly supported by the immunodetection of nuclear PPARγ in brain germinative zones of congenitally infected fetuses (N = 20), but not in control samples. Altogether, our findings reveal a key role for PPARγ in neurogenesis and in the pathophysiology of HCMV congenital infection. They also pave the way to the identification of PPARγ gene targets in the infected brain.

Resolving Lipid Mediators Maresin 1 and Resolvin D2 Prevent Atheroprogression in Mice.

RATIONALE: Atheroprogression is a consequence of nonresolved inflammation, and currently a comprehensive overview of the mechanisms preventing resolution is missing. However, in acute inflammation, resolution is known to be orchestrated by a switch from inflammatory to resolving lipid mediators. Therefore, we hypothesized that lesional lipid mediator imbalance favors atheroprogression. OBJECTIVE: To understand the lipid mediator balance during atheroprogression and to establish an interventional strategy based on the delivery of resolving lipid mediators. METHODS AND RESULTS: Aortic lipid mediator profiling of aortas from Apoe-/- mice fed a high-fat diet for 4 weeks, 8 weeks, or 4 months revealed an expansion of inflammatory lipid mediators, Leukotriene B4 and Prostaglandin E2, and a concomitant decrease of resolving lipid mediators, Resolvin D2 (RvD2) and Maresin 1 (MaR1), during advanced atherosclerosis. Functionally, aortic Leukotriene B4 and Prostaglandin E2 levels correlated with traits of plaque instability, whereas RvD2 and MaR1 levels correlated with the signs of plaque stability. In a therapeutic context, repetitive RvD2 and MaR1 delivery prevented atheroprogression as characterized by halted expansion of the necrotic core and accumulation of macrophages along with increased fibrous cap thickness and smooth muscle cell numbers. Mechanistically, RvD2 and MaR1 induced a shift in macrophage profile toward a reparative phenotype, which secondarily stimulated collagen synthesis in smooth muscle cells. CONCLUSIONS: We present evidence for the imbalance between inflammatory and resolving lipid mediators during atheroprogression. Delivery of RvD2 and MaR1 successfully prevented atheroprogression, suggesting that resolving lipid mediators potentially represent an innovative strategy to resolve arterial inflammation.

Apelin targets gut contraction to control glucose metabolism via the brain.

OBJECTIVE: The gut-brain axis is considered as a major regulatory checkpoint in the control of glucose homeostasis. The detection of nutrients and/or hormones in the duodenum informs the hypothalamus of the host's nutritional state. This process may occur via hypothalamic neurons modulating central release of nitric oxide (NO), which in turn controls glucose entry into tissues. The enteric nervous system (ENS) modulates intestinal contractions in response to various stimuli, but the importance of this interaction in the control of glucose homeostasis via the brain is unknown. We studied whether apelin, a bioactive peptide present in the gut, regulates ENS-evoked contractions, thereby identifying a new physiological partner in the control of glucose utilisation via the hypothalamus. DESIGN: We measured the effect of apelin on electrical and mechanical duodenal responses via telemetry probes and isotonic sensors in normal and obese/diabetic mice. Changes in hypothalamic NO release, in response to duodenal contraction modulated by apelin, were evaluated in real time with specific amperometric probes. Glucose utilisation in tissues was measured with orally administrated radiolabeled glucose. RESULTS: In normal and obese/diabetic mice, glucose utilisation is improved by the decrease of ENS/contraction activities in response to apelin, which generates an increase in hypothalamic NO release. As a consequence, glucose entry is significantly increased in the muscle. CONCLUSIONS: Here, we identify a novel mode of communication between the intestine and the hypothalamus that controls glucose utilisation. Moreover, our data identified oral apelin administration as a novel potential target to treat metabolic disorders.

Epithelial expression and function of trypsin-3 in irritable bowel syndrome.

OBJECTIVES: Proteases are key mediators of pain and altered enteric neuronal signalling, although the types and sources of these important intestinal mediators are unknown. We hypothesised that intestinal epithelium is a major source of trypsin-like activity in patients with IBS and this activity signals to primary afferent and enteric nerves and induces visceral hypersensitivity. DESIGN: Trypsin-like activity was determined in tissues from patients with IBS and in supernatants of Caco-2 cells stimulated or not. These supernatants were also applied to cultures of primary afferents. mRNA isoforms of trypsin (PRSS1, 2 and 3) were detected by reverse transcription-PCR, and trypsin-3 protein expression was studied by western blot analysis and immunohistochemistry. Electrophysiological recordings and Ca2+ imaging in response to trypsin-3 were performed in mouse primary afferent and in human submucosal neurons, respectively. Visceromotor response to colorectal distension was recorded in mice administered intracolonically with trypsin-3. RESULTS: We showed that stimulated intestinal epithelial cells released trypsin-like activity specifically from the basolateral side. This activity was able to activate sensory neurons. In colons of patients with IBS, increased trypsin-like activity was associated with the epithelium. We identified that trypsin-3 was the only form of trypsin upregulated in stimulated intestinal epithelial cells and in tissues from patients with IBS. Trypsin-3 was able to signal to human submucosal enteric neurons and mouse sensory neurons, and to induce visceral hypersensitivity in vivo, all by a protease-activated receptor-2-dependent mechanism. CONCLUSIONS: In IBS, the intestinal epithelium produces and releases the active protease trypsin-3, which is able to signal to enteric neurons and to induce visceral hypersensitivity.

Defects in 15-HETE Production and Control of Epithelial Permeability by Human Enteric Glial Cells From Patients With Crohn's Disease.

BACKGROUND & AIMS: Enteric glial cells (EGCs) produce soluble mediators that regulate homeostasis and permeability of the intestinal epithelial barrier (IEB). We investigated the profile of polyunsaturated fatty acid (PUFA) metabolites produced by EGCs from rats and from patients with Crohn's disease (CD), compared with controls, along with the ability of one of these metabolites, 15-hydroxyeicosatetraenoic acid (15-HETE), to regulate the permeability of the IEB. METHODS: We isolated EGCs from male Sprague-Dawley rats, intestinal resections of 6 patients with CD, and uninflamed healthy areas of intestinal tissue from 6 patients who underwent surgery for colorectal cancer (controls). EGC-conditioned media was analyzed by high-sensitivity liquid-chromatography tandem mass spectrometry to determine PUFA signatures. We used immunostaining to identify 15-HETE-producing enzymes in EGCs and tissues. The effects of human EGCs and 15-HETE on permeability and transepithelial electrical resistance of the IEB were measured using Caco-2 cells; effects on signal transduction proteins were measured with immunoblots. Levels of proteins were reduced in Caco-2 cells using short-hairpin RNAs or proteins were inhibited pharmacologically. Rats were given intraperitoneal injections of 15-HETE or an inhibitor of 15-lipoxygenase (the enzyme that produces 15-HETE); colons were collected and permeability was measured. RESULTS: EGCs expressed 15-lipoxygenase-2 and produced high levels of 15-HETE, which increased IEB resistance and reduced IEB permeability. 15-HETE production was reduced in EGCs from patients with CD compared with controls. EGCs from patients with CD were unable to reduce the permeability of the IEB; the addition of 15-HETE restored permeability to levels of control tissues. Inhibiting 15-HETE production in rats increased the permeability of the IEB in colon tissues. We found that 15-HETE regulates IEB permeability by inhibiting an adenosine monophosphate-activated protein kinase and increasing expression of zonula occludens-1. CONCLUSIONS: Enteric glial cells from patients with CD have reduced production of 15-HETE, which controls IEB permeability by inhibiting adenosine monophosphate-activated protein kinase and increasing expression of zonula occludens-1.

Nonredundant protective properties of FPR2/ALX in polymicrobial murine sepsis.

Sepsis is characterized by overlapping phases of excessive inflammation temporally aligned with an immunosuppressed state, defining a complex clinical scenario that explains the lack of successful therapeutic options. Here we tested whether the formyl-peptide receptor 2/3 (Fpr2/3)--ortholog to human FPR2/ALX (receptor for lipoxin A4)--exerted regulatory and organ-protective functions in experimental sepsis. Coecal ligature and puncture was performed to obtain nonlethal polymicrobial sepsis, with animals receiving antibiotics and analgesics. Clinical symptoms, temperature, and heart function were monitored up to 24 h. Peritoneal lavage and plasma samples were analyzed for proinflammatory and proresolving markers of inflammation and organ dysfunction. Compared with wild-type mice, Fpr2/3(-/-) animals exhibited exacerbation of disease severity, including hypothermia and cardiac dysfunction. This scenario was paralleled by higher levels of cytokines [CXCL1 (CXC receptor ligand 1), CCL2 (CC receptor ligand 2), and TNFα] as quantified in cell-free biological fluids. Reduced monocyte recruitment in peritoneal lavages of Fpr2/3(-/-) animals was reflected by a higher granulocyte/monocyte ratio. Monitoring Fpr2/3(-/-) gene promoter activity with a GFP proxy marker revealed an over threefold increase in granulocyte and monocyte signals at 24 h post-coecal ligature and puncture, a response mediated by TNFα. Treatment with a receptor peptido-agonist conferred protection against myocardial dysfunction in wild-type, but not Fpr2/3(-/-), animals. Therefore, coordinated physio-pharmacological analyses indicate nonredundant modulatory functions for Fpr2/3 in experimental sepsis, opening new opportunities to manipulate the host response for therapeutic development.

Formyl Peptide Receptor 2 Plays a Deleterious Role During Influenza A Virus Infections.

BACKGROUND: The pathogenesis of influenza A virus (IAV) infections is a multifactorial process that includes the replication capacity of the virus and a harmful inflammatory response to infection. Formyl peptide receptor 2 (FPR2) emerges as a central receptor in inflammatory processes controlling resolution of acute inflammation. Its role in virus pathogenesis has not been investigated yet. METHODS: We used pharmacologic approaches to investigate the role of FPR2 during IAV infection in vitro and in vivo. RESULTS: In vitro, FPR2 expressed on A549 cells was activated by IAV, which harbors its ligand, annexin A1, in its envelope. FPR2 activation by IAV promoted viral replication through an extracellular-regulated kinase (ERK)-dependent pathway. In vivo, activating FPR2 by administering the agonist WKYMVm-NH2 decreased survival and increased viral replication and inflammation after IAV infection. This effect was abolished by treating the mice with U0126, a specific ERK pathway inhibitor, showing that, in vivo, the deleterious role of FPR2 also occurs through an ERK-dependent pathway. In contrast, administration of the FPR2 antagonist WRW4 protected mice from lethal IAV infections. CONCLUSIONS: These data show that viral replication and IAV pathogenesis depend on FPR2 signaling and suggest that FPR2 may be a promising novel strategy to treat influenza.

In vitro and in vivo evidence for an inflammatory role of the calcium channel TRPV4 in lung epithelium: Potential involvement in cystic fibrosis.

Cystic fibrosis (CF) is an inherited disease associated with chronic severe lung inflammation, leading to premature death. To develop innovative anti-inflammatory treatments, we need to characterize new cellular and molecular components contributing to the mechanisms of lung inflammation. Here, we focused on the potential role of "transient receptor potential vanilloid-4" (TRPV4), a nonselective calcium channel. We used both in vitro and in vivo approaches to demonstrate that TRPV4 expressed in airway epithelial cells triggers the secretion of major proinflammatory mediators such as chemokines and biologically active lipids, as well as a neutrophil recruitment in lung tissues. We characterized the contribution of cytosolic phospholipase A2, MAPKs, and NF-κB in TRPV4-dependent signaling. We also showed that 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids, i.e., four natural lipid-based TRPV4 agonists, are present in expectorations of CF patients. Also, TRPV4-induced calcium mobilization and inflammatory responses were enhanced in cystic fibrosis transmembrane conductance regulator-deficient cellular and animal models, suggesting that TRPV4 is a promising target for the development of new anti-inflammatory treatments for diseases such as CF.