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Prostaglandin D 2 (PGD 2 ) is one of the most potent endogenous sleep-promoting molecules. However, the cellular and molecular mechanisms of the PGD 2 -induced activation of sleep-promoting neurons in the ventrolateral preoptic nucleus (VLPO), the major nonrapid eye movement (NREM)-sleep center, still remains unclear. We here show that PGD 2 receptors (DP 1 ) are not only expressed in the leptomeninges but also in astrocytes from the VLPO. We further demonstrate, by performing real-time measurements of extracellular adenosine using purine enzymatic biosensors in the VLPO, that PGD 2 application causes a 40% increase in adenosine level, via an astroglial release. Measurements of vasodilatory responses and electrophysiological recordings finally reveal that, in response to PGD 2 application, adenosine release induces an A 2A R-mediated dilatation of blood vessels and activation of VLPO sleep-promoting neurons. Altogether, our results unravel the PGD 2 signaling pathway in the VLPO, controlling local blood flow and sleep-promoting neurons, via astrocyte-derived adenosine.

Adenomyosis is characterised by epithelial gland and mesenchymal stroma invasion of the uterine myometrium. Adenomyosis is an oestrogen-dependent gynaecological disease in which a number of factors, such as inflammatory molecules, prostaglandins (PGs), angiogenic factors, cell proliferation and extracellular matrix remodelling proteins, also play a role as key disease mediators. In this study, we used mice lacking both lipocalin and hematopoietic-PG D synthase (L- and H-Pgds) genes in which PGD2 is not produced to elucidate PGD2 roles in the uterus. Gene expression studied by real-time PCR and hormone dosages performed by ELISA or liquid chromatography tandem mass spectroscopy in mouse uterus samples showed that components of the PGD2 signalling pathway, both PGDS and PGD2-receptors, are expressed in the mouse endometrium throughout the oestrus cycle with some differences among uterine compartments. We showed that PGE2 production and the steroidogenic pathway are dysregulated in the absence of PGD2. Histological analysis of L/H-Pgds-/- uteri, and immunohistochemistry and immunofluorescence analyses of proliferation (Ki67), endothelial cell (CD31), epithelial cell (pan-cytokeratin), myofibroblast (α-SMA) and mesenchymal cell (vimentin) markers, identify that 6-month-old L/H-Pgds-/- animals developed adenomyotic lesions, and that disease severity increased with age. In conclusion, this study suggests that the PGD2 pathway has major roles in the uterus by protecting the endometrium against adenomyosis development. Additional experiments, using for instance transcriptomic approaches, are necessary to fully determine the molecular mechanisms that lead to adenomyosis in L/H-Pgds-/- mice and to confirm whether this strain is an appropriate model for studying the human disease., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Cardiac levels of the signal transducer and activator of transcription factor-3 (STAT3) decline with age, and male but not female mice with a cardiomyocyte-specific STAT3 deficiency conditional knockout (CKO) display premature age-related heart failure associated with reduced cardiac capillary density. In the present study, isolated male and female CKO-cardiomyocytes exhibit increased prostaglandin (PG)-generating cyclooxygenase-2 (COX-2) expression. The PG-degrading hydroxyprostaglandin-dehydrogenase-15 (HPGD) expression is only reduced in male cardiomyocytes, which is associated with increased prostaglandin D2 (PGD2) secretion from isolated male but not female CKO-cardiomyocytes. Reduced HPGD expression in male cardiomyocytes derive from impaired androgen receptor (AR)-signaling due to loss of its cofactor STAT3. Elevated PGD2 secretion in males is associated with increased white adipocyte accumulation in aged male but not female hearts. Adipocyte differentiation is enhanced in isolated stem cell antigen-1 (SCA-1)+ cardiac progenitor cells (CPC) from young male CKO-mice compared with the adipocyte differentiation of male wild-type (WT)-CPC and CPC isolated from female mice. Epigenetic analysis in freshly isolated male CKO-CPC display hypermethylation in pro-angiogenic genes (Fgfr2, Epas1) and hypomethylation in the white adipocyte differentiation gene Zfp423 associated with up-regulated ZFP423 expression and a shift from endothelial to white adipocyte differentiation compared with WT-CPC. The expression of the histone-methyltransferase EZH2 is reduced in male CKO-CPC compared with male WT-CPC, whereas no differences in the EZH2 expression in female CPC were observed. Clonally expanded CPC can differentiate into endothelial cells or into adipocytes depending on the differentiation conditions. ZFP423 overexpression is sufficient to induce white adipocyte differentiation of clonal CPC. In isolated WT-CPC, PGD2 stimulation reduces the expression of EZH2, thereby up-regulating ZFP423 expression and promoting white adipocyte differentiation. The treatment of young male CKO mice with the COX inhibitor Ibuprofen or the PGD2 receptor (DP)2 receptor antagonist BAY-u 3405 in vivo increased EZH2 expression and reduced ZFP423 expression and adipocyte differentiation in CKO-CPC. Thus, cardiomyocyte STAT3 deficiency leads to age-related and sex-specific cardiac remodeling and failure in part due to sex-specific alterations in PGD2 secretion and subsequent epigenetic impairment of the differentiation potential of CPC. Causally involved is the impaired AR signaling in absence of STAT3, which reduces the expression of the PG-degrading enzyme HPGD., Competing Interests: The authors have declared that no competing interests exist.

A role for the adhesion G-protein coupled receptor ADGRE2 or EMR2 in mechanosensing was revealed by the finding of a missense substitution (p.C492Y) associated with familial vibratory urticaria. In these patients, friction of the skin induces mast cell hyper-degranulation through p.C492Y-ADGRE2, causing localized hives, flushing, and hypotension. We have now characterized the responses and intracellular signals elicited by mechanical activation in human mast cells expressing p.C492Y-ADGRE2 and attached to dermatan sulfate, a ligand for ADGRE2. The presence of p.C492Y-ADGRE2 reduced the threshold to activation and increased the extent of degranulation along with the percentage of mast cells responding. Vibration caused phospholipase C activation, transient increases in cytosolic calcium, and downstream activation of phosphoinositide 3-kinase and extracellular signal-regulated kinases 1 and 2 by Gβγ, Gα q/11 , and Gα i/o -independent mechanisms. Degranulation induced by vibration was dependent on phospholipase C pathways, including calcium, protein kinase C, and phosphoinositide 3-kinase but not extracellular signal-regulated kinases 1/2 pathways, along with pertussis toxin-sensitive signals. In addition, mechanoactivation of mast cells stimulated the synthesis and release of prostaglandin D 2 , to our knowledge a previously unreported mediator in vibratory urticaria, and extracellular signal-regulated kinases 1/2 activation was required for this response together with calcium, protein kinase C, and to some extent, phosphoinositide 3-kinase. Our studies thus identified critical molecular events initiated by mechanical forces and potential therapeutic targets for patients with vibratory urticaria., (Published by Elsevier Inc.)

Eosinophils are key regulators of adipose tissue homeostasis, thus characterization of adipose tissue-related molecular factors capable of regulating eosinophil activity is of great interest. Leptin is known to directly activate eosinophils in vitro , but leptin ability of inducing in vivo eosinophilic inflammatory response remains elusive. Here, we show that leptin elicits eosinophil influx as well as its activation, characterized by increased lipid body biogenesis and LTC 4 synthesis. Such leptin-triggered eosinophilic inflammatory response was shown to be dependent on activation of the mTOR signaling pathway, since it was (i) inhibited by rapamycin pre-treatment and (ii) reduced in PI3K-deficient mice. Local infiltration of activated eosinophils within leptin-driven inflammatory site was preceded by increased levels of classical mast cell-derived molecules, including TNFα, CCL5 (RANTES), and PGD 2 . Thus, mice were pre-treated with a mast cell degranulating agent compound 48/80 which was capable to impair leptin-induced PGD 2 release, as well as eosinophil recruitment and activation. In agreement with an indirect mast cell-driven phenomenon, eosinophil accumulation induced by leptin was abolished in TNFR-1 deficient and also in HQL-79-pretreated mice, but not in mice pretreated with neutralizing antibodies against CCL5, indicating that both typical mast cell-driven signals TNFα and PGD 2 , but not CCL5, contribute to leptin-induced eosinophil influx. Distinctly, leptin-induced eosinophil lipid body (lipid droplet) assembly and LTC 4 synthesis appears to depend on both PGD 2 and CCL5, since both HQL-79 and anti-CCL5 treatments were able to inhibit these eosinophil activation markers. Altogether, our data show that leptin triggers eosinophilic inflammation in vivo via an indirect mechanism dependent on activation of resident mast cell secretory activity and mediation by TNFα, CCL5, and specially PGD 2 ., (Copyright © 2020 Amorim, Souza-Almeida, Luna-Gomes, Bozza, Canetti, Diaz, Maya-Monteiro and Bandeira-Melo.)

Suppression of ubiquitin proteasome pathway (UPP) and stimulation of caspase-3 are involved in neurodegeneration. Can UPP activators and caspase-3 inhibitors ameliorate neurodegeneration? Here, we found a novel neuronal cell death accompanied with UPP activation and caspase-3 inhibition. Recently, plasmalemmal neuron-specific enolase (NSE) has been identified as one of membrane targets of 15-deoxy-Δ 12,14 -prostaglandin J 2 (15d-PGJ 2 ). 15d-PGJ 2 induces neuronal apoptosis via activating caspase-3 and inactivating UPP, whereas the anti-NSE antibody inactivated caspase-3, activated UPP, and caused neuronal cell death. The anti-NSE antibody activated caspase-1 (pyroptosis marker), but not condense chromatin (apoptosis marker). The anti-NSE antibody declined intracellular level of ATP, which is not altered in pyroptosis. The intracellular level of calcium is elevated in necrosis and pyroptosis, but its chelator did not ameliorate the neurotoxicity of anti-NSE. Thiol antioxidants such as N-acetyl cysteine and glutathione reduced the neurotoxicity of 15d-PGJ 2 but enhanced that of the anti-NSE antibody. The anti-NSE antibody incorporated propidium iodide into neurons through the disrupted plasma membrane, which are not observed in ferroptosis and autophagic cell death. Thus, the anti-NSE antibody induced neuronal cell death in a novel fashion distinguished from necrosis, necroptosis, apoptosis, pyroptosis, ferroptosis, and autophagic cell death.

Rationale: Fluid shear stress (FSS) maintains NOS-3 (endothelial NO synthase) expression. Homozygosity for the C variant of the T-786C single-nucleotide polymorphism of the NOS3 gene, which solely exists in humans, renders the gene less sensitive to FSS, resulting in a reduced endothelial cell (EC) capacity to generate NO. Decreased bioavailability of NO in the arterial vessel wall facilitates atherosclerosis. Consequently, individuals homozygous for the C variant have an increased risk for coronary heart disease (CHD)., Objective: At least 2 compensatory mechanisms seem to minimize the deleterious effects of this single-nucleotide polymorphism in affected individuals, one of which is characterized herein., Methods and Results: Human genotyped umbilical vein ECs and THP-1 monocytes were used to investigate the role of 15-deoxy-Δ12,14-prostaglandin J 2 (15d-PGJ 2 ) in vitro. Its concentration in plasma samples from genotyped patients with CHD and age-matched CHD-free controls was determined using quantitative ultraperformance LC-MS/MS. Exposure of human ECs to FSS effectively reduced monocyte transmigration particularly through monolayers of CC-genotype ECs. Primarily in CC-genotype ECs, FSS elicited a marked rise in COX (cyclooxygenase)-2 and L-PGDS (lipocalin-type prostaglandin D synthase) expression, which appeared to be NO sensitive, and provoked a significant release of 15d-PGJ 2 over baseline. Exogenous 15d-PGJ 2 significantly reduced monocyte transmigration and exerted a pronounced anti-inflammatory effect on the transmigrated monocytes by downregulating, for example, transcription of the IL (interleukin)-1β gene (IL1B). Reporter gene analyses verified that this effect is due to binding of Nrf2 (nuclear factor [erythroid-derived 2]-like 2) to 2 AREs (antioxidant response elements) in the proximal IL1B promoter. In patients with CHD, 15d-PGJ 2 plasma levels were significantly upregulated compared with age-matched CHD-free controls, suggesting that this powerful anti-inflammatory prostanoid is part of an endogenous defence mechanism to counteract CHD., Conclusions: Despite a reduced capacity to form NO, CC-genotype ECs maintain a robust anti-inflammatory phenotype through an enhanced FSS-dependent release of 15d-PGJ 2 .

Fetal pain and fetal anesthesia are still matter of debate: some authors hypothesize that several intrauterine endocrine neuroinhibitors (ENIn) anesthetize the fetus, keeping it in a constant state of sleep, and making pharmacological fetal anesthesia useless for fetal surgery, while others argue fetal pain is possible and shoud be prevented with fetal anesthesy., Aim: To retrieve evidences about fetal pain, fetal arousability and about the level of sedation induced by the ENIn, in order to assess the necessity of direct fetal anesthesia during prenatal fetal surgery., Methods: We performed a careful literature review (1990-2016) on fetal arousability, and on the possibility that ENIn at the average fetal blood levels induce actual anesthesia. We retrieved the papers that fulfilled the research criteria, with particular attention to the second half of pregnancy, the period when most fetal surgery is performed., Results: Fetuses are awake about 10% of the total time in the last gestational weeks, and they can be aroused by external stimuli. ENIn have not an anesthetic effect at normal fetal values, but only when they areartificialy injected at high doses; their blood levels in the last trimester of average pregnancies are not dissimilar either in the fetus or in the mother., Conclusions: During the second half of the pregnancy, external stimuli can awake the fetuses, although they spend most of the time in sleeping state; the presence of ENIn is absolutely not enough to guarantee an effective anesthesia during surgery. Thus, direct fetal analgesia/anesthesia is mandatory, though further studies on its possible drawbacks are necessary.

Prostaglandins (PGs) are divided into conventional PGs, e.g., PGD 2 , and cyclopentenone-type PGs, e.g., 15-deoxy-Δ 12,14 prostaglandin J 2 (15d-PGJ 2 ). PGD 2 is non-enzymatically metabolized to PGJ 2 , Δ 12 -PGJ 2 , and 15d-PGJ 2 . In the central nervous system, 15d-PGJ 2 differentiates embryonic midbrain cells into dopaminergic neuronal cells via its nuclear peroxysome proliferator-activated receptor-γ (PPARγ). 15d-PGJ 2 exerts conflict actions: proinflammatory and anti-inflammatory activities. In the brain, 15d-PGJ 2 possesses opposite functions as a neuroprotectant at low concentrations and a neurotoxicant at high concentrations in the brain. PPARγ contributes to the neuroprotective effect of 15d-PGJ 2 but not to the neurotoxic effect. Its membrane receptor, chemoattractant receptor-homologous molecule expressed on T-helper type 2 cells (CRTH2), is not also involved in the neurotoxicity of 15d-PGJ 2 . 15d-PGJ 2 induces neuronal apoptosis via inactivating ubiquitin proteasome pathway and activating caspase cascade. Alternatively, 15d-PGJ 2 downregulates phosphoinositide 3-kinase (PI3K)-Akt pathway and suppresses neurite outgrowth. 15d-PGJ 2 possesses α,β-unsaturated ketone moiety in its cyclopentenone ring and acts an endogenous electrophile. By the Michael addition reaction, 15d-PGJ 2 is covalently bound to cellular nucleophiles, such as free cysteine residues of proteins that regulate intracellular signaling pathways. There are specific binding sites of [ 3 H]15d-PGJ 2 in the plasma membrane of cerebral cortices. Besides CRTH2, plasmalemmal glycolytic enzymes, respiratory chain enzymes, molecular chaperones, adaptor proteins and cytoskeletons are identified as membrane targets for 15d-PGJ 2 . In the present review, we provide evidences for pathophysiological roles of 15d-PGJ 2 in the central nervous system and neurological diseases.

Regulation of the amyloid precursor protein (APP) processing by α- and β-secretases is of special interest to Alzheimer's disease (AD), as these proteases prevent or mediate amyloid beta formation, respectively. Neuroinflammation is also implicated in AD. Our data demonstrate that the endogenous mediator of inflammation prostaglandin J2 (PGJ2) promotes full-length APP (FL-APP) processing by α- and β-secretases. The decrease in FL-APP was independent of proteasomal, lysosomal, calpain, caspase, and γ-secretase activities. Moreover, PGJ2-treatment promoted cleavage of secreted APP, specifically sAPPα and sAPPβ, generated by α and β-secretase, respectively. Notably, PGJ2-treatment induced caspase-dependent cleavage of sAPPβ. Mechanistically, PGJ2-treatment selectively diminished mature (O- and N-glycosylated) but not immature (N-glycosylated only) FL-APP. PGJ2-treatment also increased the overall levels of protein O-GlcNAcylation, which occurs within the nucleocytoplasmic compartment. It is known that APP undergoes O-GlcNAcylation and that the latter protects proteins from proteasomal degradation. Our results suggest that by increasing protein O-GlcNAcylation levels, PGJ2 renders mature APP less prone to proteasomal degradation, thus shunting APP toward processing by α- and β-secretases., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Supplementation with nontoxic doses of micronutrient selenium has been shown to alleviate chronic myelogenous leukemia (CML) via the elimination of leukemia stem cells (LSCs) in mice. This treatment provides a new and novel method for eliminating the LSCs that are otherwise not targeted by existing therapies. The antileukemic effect of selenium was dependent on the production of endogenous cyclopentenone prostaglandins (CyPGs), Δ-12 prostaglandin J 2 (Δ 12 -PGJ 2 ), and 15-deoxy-Δ12,14-prostaglandin J 2 (15d-PGJ 2 ). Here, we show that these endogenous CyPGs, produced by mice maintained on selenium-supplemented diets, alleviate the symptoms of CML through their ability to activate the nuclear hormone receptor, peroxisome proliferator activated receptor γ (PPARγ). GW9662, a potent PPARγ antagonist, blocked the antileukemic effect of selenium supplementation by significantly reducing CyPGs. This effect was mediated by an increase in 15-prostaglandin dehydrogenase (15-Pgdh) activity, which oxidizes and inactivates Δ 12 -PGJ 2 and 15d-PGJ 2 In contrast, treatment with the PPARγ agonist pioglitazone mimicked selenium supplementation. This treatment led to decreased 15-Pgdh activity and increased CyPG levels, which inhibited CML progression. Selenium-dependent activation of PPARγ mediated by endogenous CyPGs decreased Stat5 expression leading to the downregulation of Cited2, a master regulator of LSC quiescence. These studies suggest a potential role for selenium supplementation as an adjuvant therapy in CML., (© 2017 by The American Society of Hematology.)

Prostaglandins (PGs) play a key role in the development on the immune response through the regulation of both pro- and anti-inflammatory processes. PGD(2) can be either pro- or anti-inflammatory depending on the inflammatory milieu. Prostaglandin D synthase (PGDS) is the enzyme responsible for the conversion of PGH(2) to PGD(2). In mammals, two types of PGDS synthase have been described, the hematopoietic (H-PGDS) and the lipocalin (L-PGDS). In the present study we describe the existence of two orthologs of the mammalian L-PGDS (PGDS1 and PGDS2) in the gilthead seabream and characterize their gene expression profiles and biological activity. The results showed a dramatic induction of the gene coding for PGDS1 in acidophilic granulocytes (AGs), which are functionally equivalent to mammalian neutrophils, after a prolonged in vitro activation with different pathogen associated molecular patterns (PAMPs). In contrast PGDS2 was not expressed in these cells. The functional relevance of the induction of PGDS1 in AGs was confirmed by the ability of these cells to release PGD(2) upon PAMP stimulation. To gain further insight into the role of PGD(2) in the resolution of inflammation in fish, we examined the ability of PGD(2) or its cyclopentenone derivates (cyPGs) to modulate the main functional activities of AGs. It was found that both PGD(2) and cyPGs inhibited the production of reactive oxygen species and downregulated the transcript levels of the gene encoding interleukin-1β. Taken together, these results demonstrate that the use of PGD(2) and its metabolites in the resolution of inflammation was established before the divergence of fish from tetrapods more than 450 million years ago and support a critical role for granulocytes in the resolution of inflammation in vertebrates., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Prostaglandin D2 (PGD2) and derivatives are lipid mediators involved in the control of the intestinal epithelial barrier homeostasis. Their involvement in the pathophysiology of chronic inflammatory bowel disease (IBD) is still debated. Several results highlight the duality of PGD2 as an anti- or pro-inflammatory mediator. This duality seems to be related to a differential expression of its receptors by intestinal epithelial cells and the surrounding immunocompetent cells. The enteric glial cells from the enteric nervous system (ENS) express the lipocalin-type-prostaglandin D synthase and secrete PGD2 and 15d-PGJ2. The protective role of the ENS in the homeostatic control of the epithelial intestinal barrier and its involvement in the pathogenesis of IBD have already been demonstrated. Thus, these lipid mediators seem to be new actors of the neuro-glio-epithelial unit and could play a crucial role maintaining gut barrier integrity., (© 2015 médecine/sciences – Inserm.)

The objective of the study was to investigate the role of prostaglandin D2 during pregnancy and its mediator Lipocalin-type prostaglandin D2 synthase (L-PGDS) as a predictor of preterm birth (PTB). Transgenic L-PGDS (+/+), L-PGDS (-/-) and C57BL/6 control pregnant mice models were used to determine the effect of DP1 and DP2 receptor antagonists in lipopolysaccharide (LPS)-induced PTB mice. In addition, L-PGDS levels were measured in the cervicovaginal secretions (CVS) of 370 pregnant women using ELISA and further processed for isoform detection using 2-D gel electrophoresis. Our results found that C57BL/6 control mice (n = 26), transgenic L-PGDS (+/+) (n = 26), demonstrated an 89% and 100% preterm birth in LPS (intraperitoneal injection, 20mg/kg) induced mice model respectively. Interestingly, the incidence of PTB was significantly reduced to 40% in L-PGDS (-/-) knockout mice (n = 26). DP1 and DP2 receptor antagonists (0.264 μg/day, dose of 0.1 μg/μl with the flow of 0.11 μl/h for 28 day using Alzet pumps) were used to investigate the effect in LPS-induced PTB in C57BL/6 mice and found 3.3-fold increase in viable pups after LPS-induction. In addition, L-PGDS levels were measured in CVS samples and found that PTB women (n = 296) had two-fold higher levels compared to full term births (n = 74) and established a significant inverse correlation between levels of L-PGDS and days to expected delivery by using 370 preterm birth CVS samples. Elevated L-PGDS levels in the CVS of women may be considered as a potential biomarker for PTB in future. Secondly, the use of DP1 and DP2 receptor antagonists may represent novel tocolytic agents for the treatment of PTB., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Our earlier work showed that knockout of hematopoietic prostaglandin D synthase (HPGDS, an enzyme that produces prostaglandin D2) caused more adenomas in Apc(Min/+) mice. Conversely, highly expressed transgenic HPGDS allowed fewer tumors. Prostaglandin D2 (PGD2) binds to the prostaglandin D2 receptor known as PTGDR (or DP1). PGD2 metabolites bind to peroxisome proliferator-activated receptor γ (PPARG). We hypothesized that Ptgdr or Pparg knockouts may raise numbers of tumors, if these receptors take part in tumor suppression by PGD2. To assess, we produced Apc(Min/+) mice with and without Ptgdr knockouts (147 mice). In separate experiments, we produced Apc(Min/+) mice expressing transgenic lipocalin-type prostaglandin D synthase (PTGDS), with and without heterozygous Pparg knockouts (104 mice). Homozygous Ptgdr knockouts raised total numbers of tumors by 30-40% at 6 and 14 weeks. Colon tumors were not affected. Heterozygous Pparg knockouts alone did not affect tumor numbers in Apc(Min/+) mice. As mentioned above, our Pparg knockout assessment also included mice with highly expressed PTGDS transgenes. Apc(Min/+) mice with transgenic PTGDS had fewer large adenomas (63% of control) and lower levels of v-myc avian myelocytomatosis viral oncogene homolog (MYC) mRNA in the colon. Heterozygous Pparg knockouts appeared to blunt the tumor-suppressing effect of transgenic PTGDS. However, tumor suppression by PGD2 was more clearly mediated by receptor PTGDR in our experiments. The suppression mechanism did not appear to involve changes in microvessel density or slower proliferation of tumor cells. The data support a role for PGD2 signals acting through PTGDR in suppression of intestinal tumors., (© 2014 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Background: Airway macrophage (AM) phagocytosis is impaired in severe asthma. Prostaglandin (PG) E2 and D2 are increased in severe asthma and suppress AM phagocytic function in vitro. In this study, we sought evidence for PG-mediated impairment of phagocytosis of inhalable carbonaceous particulate matter (PM) by AM in children with severe asthma compared with mild asthmatics and healthy controls., Methods: AM were obtained from children with asthma and healthy controls using induced sputum. AM carbon area (μm(2)) was assessed by image analysis. In a subgroup of asthmatics, urinary PGE2 and PGD2 metabolites were measured by high-performance liquid chromatography, and PM exposure at the home address was modelled. Phagocytosis of PM by human monocyte-derived macrophages and rat AM was assessed in vitro by image analysis., Results: AM carbon was 51% lower in children with moderate-to-severe asthma (n=36) compared with mild asthmatics (n=12, p<0.01) and healthy controls (n=47, p<0.01). There was no association between modelled PM exposure and AM carbon in 33 asthmatics who had a urine sample, but there was an inverse association between AM carbon and urinary metabolites of PGE2 and D2 (n=33, rs=-0.40, p<0.05, and rs=-0.44, p<0.01). PGE2 10(-6) M, but not PGD2 10(-6) M, suppressed phagocytosis of PM10 by human macrophages in vitro (p<0.05 vs control). PGE2 10(-6) M also suppressed phagocytosis of PM10 by rat AM in vitro (p<0.01 vs control)., Conclusions: Phagocytosis of inhaled carbonaceous PM by AMs is impaired in severe asthma. PGE2 may contribute to impaired AM phagocytic function in severe asthma., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Yawning is a behavior to which little research has been devoted. However, its purpose has not yet been demonstrated and remains controversial. In this article, we propose a new theory involving the brain network that is functional during the resting state, that is, the default mode network. When this network is active, yawning manifests a process of switching to the attentional system through its capacity to increase circulation of cerebrospinal fluid (CSF), thereby increasing clearance of somnogenic factors (prostaglandin D(2), adenosine, and others) accumulating in the cerebrospinal fluid., (Copyright © 2013 Wiley Periodicals, Inc.)

Background: Although niacin often has beneficial effects on the lipoprotein profile, flushing is an untoward effect associated with its use. Aspirin can only reduce the flushing response by 30-40%. Thus, the aim of the present study was to investigate the mechanisms of niacin-induced flushing, with and without aspirin, in normal, healthy individuals., Methods: Niacin-induced flushing was evaluated in 30 healthy individuals after oral administration of 1000 mg niacin alone or with 325 mg aspirin. Neurological, autonomic nervous system, and skin blood flow measurements (using laser Doppler on the glabrous and hairy skin of each participant) were made at various times after drug administration. In addition, the systemic release of 9α,11β-prostaglandin (PG) F(2) was determined. Flushing symptoms of redness, warmth, tingling, itching, and intensity were recorded using the modified Flushing ASsessment Tool (FAST)., Results: After aspirin, the mean flushing scores for all symptoms decreased significantly; however, 36-53% of participants still had some degree of symptoms, even though aspirin completely blocked 11β-PGF(2) synthesis. Maximum skin blood flow (MaxSkBF) in both the glabrous and hairy forearm increased significantly after niacin, but decreased significantly after aspirin only in hairy skin. Regression analysis showed that, in glabrous skin, both PGF(2) and parasympathetic activity were significant predictors of MaxSkBF after niacin, contributing 26% and 14%, respectively (total R(2) = 40%)., Conclusions: The present study indicates, for the first time, that the parasympathetic nervous system, in addition to PGD(2) , may play an important role in niacin-induced flushing. Changing the sympathetic/parasympathetic balance in favor of parasympathetic activation may be a good therapeutic target to reduce niacin-induced flushing., (© 2012 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.)

Interleukin (IL)-13 is a cytokine produced by activated CD4(+) T cells that plays a critical role in promoting allergic responses and tumor cell growth. The 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)) is a natural ligand for the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ), a known regulator of anti-inflammatory activities. We determined the effects of 15d-PGJ(2) on IL-13 expression in the Jurkat E6.1 T-cell line and in peripheral blood mononuclear cells. Semi-quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay revealed that treatment of activated T cells with 15d-PGJ(2) significantly decreased IL-13 mRNA transcription and secretion, respectively. This inhibition by 15d-PGJ(2) was independent of PPAR-γ since treatment with GW9662, an irreversible antagonist of the nuclear receptor, produced no effect. Our data also revealed the involvement of nuclear factor-κB in mediating 15d-PGJ(2)-dependent down regulation of IL-13 expression. Collectively, these results demonstrate the potential of 15d-PGJ(2) in attenuating expression and production of IL-13 in activated T cells., (Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.)

Lung fibroblasts are responsible for collagen secretion during normal tissue repair and the development of fibrosis. Many other prostaglandins have been reported to regulate collagen synthesis in lung fibroblasts, but the role of prostaglandin D2 (PGD2) is unknown. In this study, we investigated the effect of PGD2 on type I collagen secretion in human lung fibroblasts. Pretreatment with PGD2 (0.1 - 10 μM, 1 h) significantly attenuated type I collagen secretion to the cell supernatant induced by transforming growth factor-β (TGF-β). Although an agonist on chemoattractant receptorhomologous molecule expressed on Th2 cells (CRTH2) did not have any effect, the prostanoid DP-receptor agonist BW245C (0.01 - 1 μM) suppressed TGF-β-induced collagen secretion. PGD2 and BW245C significantly increased intracellular cAMP level. One-hour pretreatment with forskolin (0.1 - 10 μM), dibutyryl-cAMP (0.01 - 1 mM), and the protein kinase A (PKA)-activator N(6)-phenyl-cyclic AMP (100 μM) significantly reduced TGF-β-induced collagen secretion, while exchange protein activated by cAMP (Epac) activator 8-bromo-2'-O-methyladenosine-3',5'-cyclic AMP (10 μM) did not affect collagen deposition. These results suggest that PGD2 inhibits TGF-β-induced collagen secretion via intracellular cAMP accumulation through activating DP receptor.

Prostaglandin (PG) D(2), the most abundant PG in the central nervous system (CNS), is a bioactive lipid having various central actions including sleep induction, hypothermia and modulation of the pain response. We found that centrally administered PGD(2) stimulates food intake via the DP(1) among the two receptor subtypes for PGD(2) in mice. Hypothalamic mRNA expression of lipocalin-type PGD synthase (L-PGDS), which catalyzes production of PGD(2) from arachidonic acid via PGH(2) in the CNS, was increased after fasting. Central administration of antagonist and antisense ODN for the DP(1) receptor remarkably decreased food intake, body weight and fat mass. The orexigenic activity of PGD(2) was also blocked by an antagonist of Y(1) receptor for NPY, the most potent orexigenic peptide in the hypothalamus. Thus, the central PGD(2)-NPY system may play a critical role in food intake regulation under normal physiological conditions. We also found that orally active orexigenic peptide derived from food protein activates the PGD(2)-NPY system, downstream of δ opioid receptor. We revealed that the δ agonist peptide, rubiscolin-6-induced orexigenic activity was mediated by L-PGDS in the leptomeninges but not parenchyma using conditional knockout mice. In this review, we discuss the PGD(2)-NPY system itself, and orexigenic signals to activate it., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

We have previously described a stimulatory effect of testosterone on cyclooxygenase 2 (COX2) expression and prostaglandin (PG) synthesis, and the involvement of PGs in the modulation of testosterone production in Leydig cells of the seasonal breeder Syrian hamster. In this study, we investigated the existence of a COX2/PGs system in hamster Sertoli cells, its regulation by testosterone and FSH, and its effect on glucose uptake. COX2 expression was observed in Sertoli cells of both reproductively active and inactive adult hamsters. Testosterone and the plasma membrane-impermeable testosterone-BSA significantly induced COX2 expression, mitogen activated protein kinases 1/2 (MAPK1/2) phosphorylation and 15d-Δ(12,14)PGJ(2) production in Sertoli cells purified from photoperiodically regressed hamsters. These actions were abolished by the antiandrogen bicalutamide and by the inhibitor of MAPK kinase (MEK1/2) U0126, suggesting that testosterone exerts its stimulatory effect on COX2/PGs through a non-classical mechanism that involves the presence of androgen receptors and MAPK1/2 activation. FSH also stimulated COX2/PGs via MAPK1/2 phosphorylation. FSH and testosterone stimulate, whereas 15d-Δ(12,14)PGJ(2) via PPARγ inhibits, [2,6-(3)H]-2-deoxy-d-glucose ([(3)H]-2-DOG) uptake. Meloxicam, a selective COX2 inhibitor, further increases [(3)H]-2-DOG uptake in the presence of FSH or testosterone. Thus, in addition to their positive effect, FSH and testosterone may also exert an indirect negative regulation on glucose uptake which involves the COX2/15d-Δ(12,14)PGJ(2)/PPARγ system. Overall, these results demonstrate the presence of a COX2/PG system in hamster Sertoli cells which might act as a local modulator of FSH and testosterone actions., (Copyright © 2012 Elsevier Inc. All rights reserved.)

We found that tryptic digest of ovalbumin after oral (p.o.) and intraperitoneal (i.p.) administration exhibited anxiolytic-like activity in mice, and then searched for orally active low-molecular-weight peptides with anxiolytic-like activity in the tryptic digest. Val-Tyr-Leu-Pro-Arg, named ovolin, corresponding to ovalbumin (280-284), mimicked the anxiolytic-like activity after p.o. and i.p. administration. The anxiolytic-like activity of ovolin was inhibited by indomethacin, a cyclooxygenase (COX) inhibitor, or BWA868C, an antagonist of the DP1 receptor for prostaglandin (PG) D2 . Ovolin-induced anxiolytic-like activity was also blocked by SCH58261 or bicuculline, antagonists of the adenosine A2A and GABAA receptors, respectively. Ovolin has no affinity for the DP1 , A2A and GABAA receptors. Taken together, ovolin may exhibit anxiolytic-like activity in a manner dependent on the PGD2 -DP1 system coupled to the A2A and GABAA receptors., (© 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.)

Prostaglandin (PG) D2 is the endogenous somnogen that accumulates in the brain during prolonged wakefulness. PGD2 is produced by lipocalin-type PGD synthase localized in the leptomeninges, choroid plexus and oligodendrocytes, and circulates in the cerebrospinal fluid as a sleep hormone. PGD2 stimulates DP1 receptors and increases the local extracellular concentration of adenosine in the basal forebrain as a paracrine sleep-promoting molecule. Adenosine activates sleep-active neurons in the ventrolateral preoptic area (VLPO) through adenosine A2A receptors. Sleep-promoting neurons in the VLPO send inhibitory signals to suppress the histaminergic neurons in the tuberomammillary nucleus, which contribute to arousal through histamine H1 receptors. The neural network between VLPO and TMN is considered to play a key role in the regulation of sleep.

The clinical use of niacin to treat dyslipidemic conditions is limited by noxious side effects, most commonly facial flushing. In mice, niacin-induced flushing results from COX-1-dependent formation of PGD₂ and PGE₂ followed by COX-2-dependent production of PGE₂. Consistent with this, niacin-induced flushing in humans is attenuated when niacin is combined with an antagonist of the PGD₂ receptor DP1. NSAID-mediated suppression of COX-2-derived PGI₂ has negative cardiovascular consequences, yet little is known about the cardiovascular biology of PGD₂. Here, we show that PGD₂ biosynthesis is augmented during platelet activation in humans and, although vascular expression of DP1 is conserved between humans and mice, platelet DP1 is not present in mice. Despite this, DP1 deletion in mice augmented aneurysm formation and the hypertensive response to Ang II and accelerated atherogenesis and thrombogenesis. Furthermore, COX inhibitors in humans, as well as platelet depletion, COX-1 knockdown, and COX-2 deletion in mice, revealed that niacin evoked platelet COX-1-derived PGD₂ biosynthesis. Finally, ADP-induced spreading on fibrinogen was augmented by niacin in washed human platelets, coincident with increased thromboxane (Tx) formation. However, in platelet-rich plasma, where formation of both Tx and PGD₂ was increased, spreading was not as pronounced and was inhibited by DP1 activation. Thus, PGD₂, like PGI₂, may function as a homeostatic response to thrombogenic and hypertensive stimuli and may have particular relevance as a constraint on platelets during niacin therapy.

PGD(2) exerts a number of proinflammatory responses through a high-affinity interaction with chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) and has been detected at high concentrations at sites of allergic inflammation. Because cysteinyl leukotrienes (cysLTs) are also produced during the allergic response, we investigated the possibility that cysLTs may modulate the response of human Th2 cells to PGD(2). PGD(2) induced concentration-dependent Th2 cytokine production in the absence of TCR stimulation. Leukotrienes D(4) and E(4) (LTE(4)) also stimulated the cytokine production but were much less active than PGD(2). However, when combined with PGD(2), cysLTs caused a greater than additive enhancement of the response, with LTE(4) being most effective in activating Th2 cells. LTE(4) enhanced calcium mobilization in response to PGD(2) in Th2 cells without affecting endogenous PGD(2) production or CRTH2 receptor expression. The effect of LTE(4) was inhibited by montelukast but not by the P2Y(12) antagonist methylthioadenosine 5'-monophosphate. The enhancing effect was also evident with endogenous cysLTs produced from immunologically activated mast cells because inhibition of cysLT action by montelukast or cysLT synthesis by MK886, an inhibitor of 5-lipoxygenase-activating protein, reduced the response of Th2 cells to the levels produced by PGD(2) alone. These findings reveal that cysLTs, in particular LTE(4), have a significant proinflammatory impact on T cells and demonstrate their effects on Th2 cells are mediated by a montelukast-sensitive receptor.

Liver X receptors (LXRs) are ligand-activated transcription factors of the nuclear receptor superfamily. They play important roles in controlling cholesterol homeostasis and as regulators of inflammatory gene expression and innate immunity, by blunting the induction of classical pro-inflammatory genes. However, opposite data have also been reported on the consequences of LXR activation by oxysterols, resulting in the specific production of potent pro-inflammatory cytokines and reactive oxygen species (ROS). The effect of the inflammatory state on the expression of LXRs has not been studied in human cells, and constitutes the main aim of the present work. Our data show that when human neutrophils are triggered with synthetic ligands, the synthesis of LXRα mRNA became activated together with transcription of the LXR target genes ABCA1, ABCG1 and SREBP1c. An inflammatory mediator, 15-deoxy-Δ(12,14)-prostaglandin J(2) (15dPGJ(2)), hindered T0901317-promoted induction of LXRα mRNA expression together with transcription of its target genes in both neutrophils and human macrophages. This down-regulatory effect was dependent on the release of reactive oxygen species elicited by 15dPGJ(2), since it was enhanced by pro-oxidant treatment and reversed by antioxidants, and was also mediated by ERK1/2 activation. Present data also support that the 15dPGJ(2)-induced serine phosphorylation of the LXRα molecule is mediated by ERK1/2. These results allow to postulate that down-regulation of LXR cellular levels by pro-inflammatory stimuli might be involved in the development of different vascular diseases, such as atherosclerosis.

PGD(2) is a key mediator of allergic inflammatory diseases that is mainly synthesized by mast cells, which constitutively express high levels of the terminal enzyme involved in PGD(2) synthesis, the hematopoietic PGD synthase (H-PGDS). In this study, we investigated whether eosinophils are also able to synthesize, and therefore, supply biologically active PGD(2). PGD(2) synthesis was evaluated within human blood eosinophils, in vitro differentiated mouse eosinophils, and eosinophils infiltrating inflammatory site of mouse allergic reaction. Biological function of eosinophil-derived PGD(2) was studied by employing inhibitors of synthesis and activity. Constitutive expression of H-PGDS was found within nonstimulated human circulating eosinophils. Acute stimulation of human eosinophils with A23187 (0.1-5 μM) evoked PGD(2) synthesis, which was located at the nuclear envelope and was inhibited by pretreatment with HQL-79 (10 μM), a specific H-PGDS inhibitor. Prestimulation of human eosinophils with arachidonic acid (10 μM) or human eotaxin (6 nM) also enhanced HQL-79-sensitive PGD(2) synthesis, which, by acting on membrane-expressed specific receptors (D prostanoid receptors 1 and 2), displayed an autocrine/paracrine ability to trigger leukotriene C(4) synthesis and lipid body biogenesis, hallmark events of eosinophil activation. In vitro differentiated mouse eosinophils also synthesized paracrine/autocrine active PGD(2) in response to arachidonic acid stimulation. In vivo, at late time point of the allergic reaction, infiltrating eosinophils found at the inflammatory site appeared as an auxiliary PGD(2)-synthesizing cell population. Our findings reveal that eosinophils are indeed able to synthesize and secrete PGD(2), hence representing during allergic inflammation an extra cell source of PGD(2), which functions as an autocrine signal for eosinophil activation.

Decline in immune function with age has been attributed to defects or alterations in both the innate and the adaptive immune system. In this issue of the JCI, Zhao and coworkers provide evidence for a novel mechanism of immune dysfunction in aging mice. They show that migration of respiratory DCs from the site of virus replication to the draining lymph nodes in response to infection with several different respiratory viruses is markedly diminished with increasing age. The impaired DC migration was a result of increased levels of the lipid mediator prostaglandin D(2) (PGD(2)) in the respiratory tract with age and could be partially reversed by blockade of PGD(2) synthesis or action.

Prostaglandin (PG) D2 is the most potent endogenous sleep-promoting substance. PGD2 is produced by lipocalin-type PGD synthase localized in the leptomeninges, choroid plexus, and oligodendrocytes in the brain, and is secreted into the cerebrospinal fluid as a sleep hormone. PGD2 stimulates DP1 receptors localized in the leptomeninges under the basal forebrain and the hypothalamus. As a consequence, adenosine is released as a paracrine sleep-promoting molecule to activate adenosine A2A receptor-expressing sleep-promoting neurons and to inhibit adenosine A1 receptor-possessing arousal neurons. PGD2 activates a center of non-rapid eye movement (NREM) sleep regulation in the ventrolateral preoptic area, probably mediated by adenosine signaling, which activation inhibits the histaminergic arousal center in the tuberomammillary nucleus via descending GABAergic and galaninergic projections. The administration of a lipocalin-type PGD synthase inhibitor (SeCl4), DP1 antagonist (ONO-4127Na) or adenosine A2A receptor antagonist (caffeine) suppresses both NREM and rapid eye movement (REM) sleep, indicating that the PGD2-adenosine system is crucial for the maintenance of physiological sleep., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The morbidity and mortality associated with respiratory virus infection is felt most keenly among the elderly. T cells are necessary for viral clearance, and many age-dependent intrinsic T cell defects have been documented. However, the development of robust T cell responses in the lung also requires respiratory DCs (rDCs), which must process antigen and migrate to draining LNs (DLNs), and little is known about age-related defects in these T cell-extrinsic functions. Here, we show that increases in prostaglandin D(2) (PGD(2)) expression in mouse lungs upon aging correlate with a progressive impairment in rDC migration to DLNs. Decreased rDC migration resulted in diminished T cell responses and more severe clinical disease in older mice infected with respiratory viruses. Diminished rDC migration associated with virus-specific defects in T cell responses and was not a result of cell-intrinsic defect, rather it reflected the observed age-dependent increases in PGD(2) expression. Blocking PGD(2) function with small-molecule antagonists enhanced rDC migration, T cell responses, and survival. This effect correlated with upregulation on rDCs of CCR7, a chemokine receptor involved in DC chemotaxis. Our results suggest that inhibiting PGD(2) function may be a useful approach to enhance T cell responses against respiratory viruses in older humans.

Memory lymphocytes support inflammatory and immune responses. To do this, they enter tissue via blood vascular endothelial cells (BVEC) and leave tissue via lymphatic vascular endothelial cells (LVEC). In this study, we describe a hierarchy of signals, including novel regulatory steps, which direct the sequential migration of human T cells across the blood and the lymphatic EC. Cytokine-stimulated (TNF and IFN) human BVEC preferentially recruited memory T cells from purified PBL. Lymphocyte recruitment from flow could be blocked using a function-neutralizing Ab against CXCR3. However, a receptor antagonist directed against the PGD(2) receptor DP2 (formerly chemoattractant receptor-homologous molecule expressed on Th2 cells) inhibited transendothelial migration, demonstrating that the sequential delivery of the chemokine and prostanoid signals was required for efficient lymphocyte recruitment. CD4(+) T cells recruited by BVEC migrated with significantly greater efficiency across a second barrier of human LVEC, an effect reproduced by the addition of exogenous PGD(2) to nonmigrated cells. Migration across BVEC or exogenous PGD(2) modified the function, but not the expression, of CCR7, so that chemotaxis toward CCL21 was significantly enhanced. Thus, chemokines may not regulate all stages of lymphocyte migration during inflammation, and paradigms describing their trafficking may need to account for the role of PGD(2).

Unlabelled: Peroxisome proliferators-activated receptor-γ (PPAR-γ) is a ligand-activated transcription factor. 15 deoxy-(12,14) prostaglandin J(2) (15d-PGJ(2)) is a potent PPAR-γ ligand and acts as an anti-inflammatory agent via PPAR-γ-dependent and independent mechanisms. Helicobacter pylori (H. pylori) induces gastric inflammation by inducing the activation of oxidant-sensitive transcription factor NF-κB and cytokine expression in gastric epithelial cells. Since 15d-PGJ(2) inhibits NF-κB activation in various cells, it may suppress H. pylori-induced inflammatory signaling and cytokine expression in gastric epithelial cells. The present study aims to determined the effect of 15d-PGJ(2) on the activation of inflammatory mediators Jak/Stat (Janus kinase/signal transducers and activators of transcription) and induction of cytokine RANTES in H. pylori-infected gastric epithelial AGS cells. Since NADPH oxidase is a candidate for the production of reactive oxygen species in H. pylori-infected gastric epithelial cells, we determined the effect of 15d-PGJ(2) on the activation of NADPH oxdase. AGS cells were cultured in the presence of H. pylori treated with or without 15d-PGJ(2). The activations of NADPH oxidase and Jak1/Stat3, the levels of H(2)O(2) and RANTES in the medium, and DNA binding activity of Stat3 were assessed. A Jak/Stat3 specific inhibitor AG490 and an inhibitor of NADPH oxidase diphenyleneiodonium (DPI) were treated to determine the direct involvement of Jak/Stat and NADPH oxidase on the production of H(2)O(2) and RANTES in H. pylori-infected cells. H. pylori induced the production of H(2)O(2) and RANTES as well as the activations of NADPH oxidase and Jak1/Stat3, which were inhibited by the treatment of 15d-PGJ(2). DPI suppressed H. pylori-induced alterations similar to 15d-PGJ(2). However, AG490 had no effect on NADPH oxidase activation, but reduced the level of RANTES in the medium released from H. pylori-infected cells., Conclusion: NADPH oxidase activation is an upstream signaling of Jak1/Stat3 activation and induction of RANTES in H. pylori-infected AGS cells. 15d-PGJ(2), inhibits the activations of NADPH oxidase and Jak1/Stat3 and RANTES expression, suggesting that 15d-PGJ(2) may be beneficial for the treatment of H. pylori-induced gastric inflammation.

Histaminergic neurons solely originate from the tuberomammillary nucleus (TMN) in the posterior hypothalamus and send widespread projections to the whole brain. Experiments in rats show that histamine release in the central nervous system is positively correlated with wakefulness and the histamine released is 4 times higher during wake episodes than during sleep episodes. Endogeneous prostaglandin E2 and orexin activate histaminergic neurons in the TMN to release histamine and promote wakefulness. Conversely, prostaglandin D2 and adenosine inhibit histamine release by increasing GABA release in the TMN to induce sleep. This paper reviews the effects and mechanisms of action of the histaminergic system on sleep-wake regulation, and briefly discusses the possibility of developing novel sedative-hypnotics and wakefulness-promoting drugs related to the histaminergic system.

Prostaglandin D₂ (PGD₂) is a major prostanoid, produced mainly by mast cells, in allergic diseases, including bronchial asthma. PGD₂-induced vasodilatation and increased permeability are well-known classical effects that may be involved in allergic inflammation. Recently, novel functions of PGD₂ have been identified. To date, D prostanoid receptor (DP) and chemoattractant receptor homologous molecule expressed on T(H)2 cells (CRTH2) have been shown to be major PGD₂-related receptors. These two receptors have pivotal roles mediating allergic diseases by regulating the functions of various cell types, such as T(H)2 cells, eosinophils, basophils, mast cells, dendritic cells, and epithelial cells. This review will focus on the current understanding of the roles of PGD₂ and its metabolites in T(H)2 inflammation and the pathogenesis of bronchial asthma.

Rationale: Severe asthma (SA) remains poorly understood. Mast cells (MC) are implicated in asthma pathogenesis, but it remains unknown how their phenotype, location, and activation relate to asthma severity., Objectives: To compare MC-related markers measured in bronchoscopically obtained samples with clinically relevant parameters between normal subjects and subjects with asthma to clarify their pathobiologic importance., Methods: Endobronchial biopsies, epithelial brushings, and bronchoalveolar lavage were obtained from subjects with asthma and normal subjects from the Severe Asthma Research Program (N = 199). Tryptase, chymase, and carboxypeptidase A (CPA)3 were used to identify total MC (MC(Tot)) and the MC(TC) subset (MCs positive for both tryptase and chymase) using immunostaining and quantitative real-time polymerase chain reaction. Lavage was analyzed for tryptase and prostaglandin D2 (PGD2) by ELISA., Measurements and Main Results: Submucosal MC(Tot) (tryptase-positive by immunostaining) numbers were highest in "mild asthma/no inhaled corticosteroid (ICS) therapy" subjects and decreased with greater asthma severity (P = 0.002). In contrast, MC(TC) (chymase-positive by immunostaining) were the predominant (MC(TC)/MC(Tot) > 50%) MC phenotype in SA (overall P = 0.005). Epithelial MC(Tot) were also highest in mild asthma/no ICS, but were not lower in SA. Instead, they persisted and were predominantly MC(TC). Epithelial CPA3 and tryptase mRNA supported the immunostaining data (overall P = 0.008 and P = 0.02, respectively). Lavage PGD2 was higher in SA than in other steroid-treated groups (overall P = 0.02), whereas tryptase did not differentiate the groups. In statistical models, PGD2 and MC(TC)/MC(Tot) predicted SA., Conclusions: Severe asthma is associated with a predominance of MC(TC) in the airway submucosa and epithelium. Activation of those MC(TC) may contribute to the increases in PGD2 levels. The data suggest an altered and active MC population contributes to SA pathology.

Cyclopentenone prostaglandins (CyPGs), such as 15-deoxy-Δ(12,14) -prostaglandin J(2) (15d-PGJ(2)), are active prostaglandin metabolites exerting a variety of biological effects that may be important in the pathogenesis of neurological diseases. Ubiquitin-C-terminal hydrolase L1 (UCH-L1) is a brain specific deubiquitinating enzyme whose aberrant function has been linked to neurodegenerative disorders. We report that [15d-PGJ(2)] detected by quadrapole mass spectrometry (MS) increases in rat brain after temporary focal ischemia, and that treatment with 15d-PGJ(2) induces accumulation of ubiquitinated proteins and exacerbates cell death in normoxic and hypoxic primary neurons. 15d-PGJ(2) covalently modifies UCH-L1 and inhibits its hydrolase activity. Pharmacologic inhibition of UCH-L1 exacerbates hypoxic neuronal death while transduction with a TAT-UCH-L1 fusion protein protects neurons from hypoxia. These studies indicate that UCH-L1 function is important in hypoxic neuronal death and that excessive production of CyPGs after stroke may exacerbate ischemic injury by modification and inhibition of UCH-L1., (Published by Elsevier Inc.)

The molecular mechanism of the angiogenic effect of laminin (Ln) was studied using human umbilical vein endothelial cells (HUVECs) maintained in culture on Ln-1 substratum. High-pressure liquid chromatography analysis showed that in cells maintained on Ln, the levels of proangiogenic prostaglandin E(2) (PGE(2)) increased and that of antiangiogenic PGD(2) decreased. The angiogenic effect of PGE(2) and PGD(2) was confirmed by assessing the expression of CD31 and E-selectin in HUVECs. Immunoblot analysis, reverse transcription-polymerase chain reaction and cyclooxygenase (COX) assay showed increase in the expression and activity of COX-2 in cells maintained on Ln. Use of pharmacological inhibitors suggested that the modulation in the expression of COX-2 and thereby the levels of PGE(2) and PGD(2) in endothelial cells by Ln is mediated through the α(6)β(4) integrin-p38MAPK (mitogen-activated protein kinase)-NF-κB signaling pathway.

The enteric nervous system (ENS) and its major component, enteric glial cells (EGCs), have recently been identified as a major regulator of intestinal epithelial barrier functions. Indeed, EGCs inhibit intestinal epithelial cell (IEC) proliferation and increase barrier resistance and IEC adhesion via the release of EGC-derived soluble factors. Interestingly, EGC regulation of intestinal epithelial barrier functions is reminiscent of previously reported peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent functional effects. In this context, the present study aimed at identifying whether EGC could synthesize and release the main PPARgamma ligand, 15-deoxy-(12,14)-prostaglandin J2 (15dPGJ2), and regulate IEC functions such as proliferation and differentiation via a PPARgamma dependent pathway. First, we demonstrated that the lipocalin but not the haematopoetic form for prostaglandin D synthase (PGDS), the enzyme responsible of 15dPGJ2 synthesis, was expressed in EGCs of the human submucosal plexus and of the subepithelium, as well as in rat primary culture of ENS and EGC lines. Next, 15dPGJ2 was identified in EGC supernatants of various EGC lines. 15dPGJ2 reproduced EGC inhibitory effects upon IEC proliferation, and inhibition of lipocalin PGDS expression by shRNA abrogated these effects. Furthermore, EGCs induced nuclear translocation of PPARgamma in IEC, and both EGC and 15dPGJ2 effects upon IEC proliferation were prevented by the PPARgamma antagonist GW9662. Finally, EGC induced differentiation-related gene expression in IEC through a PPARgamma-dependent pathway. Our results identified 15dPGJ2 as a novel glial-derived mediator involved in the control of IEC proliferation/differentiation through activation of PPARgamma. They also suggest that alterations of glial PGDS expression may modify intestinal epithelial barrier functions and be involved in the development of pathologies such as cancer or inflammatory bowel diseases.

We have recently found that prostaglandin (PG) D(2) stimulates food intake via DP(1) receptor. Here we show that complement C5a stimulates food intake by activating the orexigenic PGD(2) system. C5a (30-100 pmol/mouse), after intracerebroventricular administration, stimulated food intake in non-food-deprived mice. The orexigenic activity of C5a was blocked by co-administration of a DP(1) receptor antagonist, BWA868C. Central administration of C5a elevated the hypothalamic mRNA expression of COX-2 but not COX-1, and the food intake stimulation of C5a was inhibited by pretreatment with a COX-2 inhibitor, celecoxib, suggesting that C5a activates COX-2 upstream of the PGD(2)-DP(1) system. The orexigenic activity of C5a was also inhibited by an antagonist for neuropeptide Y (NPY) Y(1) receptor, which was activated downstream of the PGD(2)-DP(1) system. These results suggest that C5a stimulates food intake via a PGD(2)- and NPY-dependent mechanism. C5a is the first example of orexigenic peptides acting through the PGD(2)-NPY system in the central nervous system.

Propionibacterium acnes is considered to be involved in the aggravation of acne vulgaris, but it remains unclear whether P. acnes directly influences lipogenesis in sebaceous glands. In this study, we showed that a culture medium of P. acnes (acnes-CM) and formalin-killed P. acnes (F-acnes) prepared from P. acnes strains, JCM6473 and JCM6425, intracellularly augmented lipid droplet formation and triacylglycerol (TG) synthesis in undifferentiated and insulin-differentiated hamster sebocytes. Acnes-CM and F-acnes prepared from four clinical P. acnes strains elicited the same lipogenesis augmentation. The augmented TG production resulted from an increase in the diacylglycerol acyltransferase activity. Topical application of acnes-CM to the skin of hamster auricles every day for 4 weeks revealed that sebum accumulation was augmented in sebaceous glands and ducts. Furthermore, both acnes-CM and F-acnes increased the production of 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), a cytochrome P450 (CYP)-linked sebaceous lipogenic factor, in differentiated sebocytes. A CYP inhibitor, SKF-525A, decreased the acnes-CM- and F-acnes-augmented production of TG and 15d-PGJ(2). Thus, to our knowledge these results provide previously unreported evidence that P. acnes directly participates in the augmentation of sebaceous lipogenesis through a proposed mechanism in which an increase of 15d-PGJ(2) production through the CYP pathway is closely associated with the enhancement of TG production.

Lipid peroxidation (LPO) has been shown to induce disturbance of membrane organization and functional loss and modification of proteins and DNA bases, and it has been implicated in the pathogenesis of various diseases. At the same time, LPO products have been shown to act as redox signaling mediators. Free and ester forms of both polyunsaturated fatty acids and cholesterol are important substrates for LPO in vivo and they are oxidized by both enzymatic and nonenzymatic mechanisms to give a variety of products. The results of numerous studies reported in the literatures show that the levels of LPO products in plasma of healthy human subjects are below 1 muM and that the molar ratios of LPO products to the respective parent lipids are below 1/1000, that is, below 0.1%. The levels of LPO products in human erythrocytes were found to be higher than those in plasma. Considerable levels of cholesterol oxidation products were observed. Although many LPO products exert cytotoxicity, sublethal concentrations of LPO products induce cellular adaptive responses and enhance tolerance against subsequent oxidative stress through upregulation of antioxidant compounds and enzymes. This adaptive response is observed not only for chemically reactive alpha,beta-unsaturated carbonyl compounds such as 4-hydroxy-2-nonenal and 15-deoxy-delta-12,14-prostaglandin J(2) but also for chemically stable compounds such as hydroxyoctadecadienoic acid, hydroxylcholesterol, and lysophosphatidylcholine. Such opposite dual functions of LPO products imply that LPO, and probably oxidative stress in general, may exert both deleterious and beneficial effects in vivo. LPO as well as reactive oxygen and nitrogen species has been shown to play an important role as a regulator of gene expression and cellular signaling messenger. In order to exert physiologically important functions as a regulator of gene expression and mediator of cellular signaling, the formation of LPO products must be strictly controlled and programmed. In contrast to LPO products by enzymatic oxidation, it appears difficult to regulate the formation of free radical-mediated LPO products. Even such unregulated LPO products may exert beneficial effects at low levels, but excessive unregulated LPO may lead to pathological disorders and diseases.

Prostaglandin (PG) D2 and adenosine are potent endogenous somnogens and their sleep-inducing mechanisms are well characterized. We examined the contribution of these somnogens to physiological sleep by the combination of pharmacological tools and gene-knockout (KO) mice. Complete insomnia was observed in wild-type mice after an intraperitoneal injection of SeCl4, an inhibitor of PGD synthase (PGDS), or caffeine, an antagonist of adenosine A2A receptors. The SeCl4-induced insomnia was not observed in PGDS- or DP1 receptor-KO mice and the caffeine-induced insomnia, in A(2A) receptor-KO mice. A DP1 antagonist, ONO-4127Na, reduced sleep of rats by 30% during infusion into the subarachnoid space of the basal forebrain. These results indicate that the PGD2/ adenosine system plays a critical role in the regulation of physiological sleep.

We have previously reported the cyclopentenone prostaglandin 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) induces renal proximal epithelial cell death through NF-kappaB inhibition. However, the upstream and down-stream signaling pathways that NF-kappaB inhibition mediates 15d-PGJ(2)-induced apoptosis remain to be defined. In the present study, we determined whether NF-kappaB inhibition induces cell death through the mitochondrial apoptotic pathway and whether protein kinase A (PKA) functions upstream of NF-kappaB inhibition by 15d-PGJ(2). The role of NF-kappaB inhibition in this apoptotic pathway was evaluated using NF-kappaB p65 transfected cells. 15d-PGJ(2) induced cell death by a PPARgamma-independent mechanism and the cell death was prevented by NF-kappaB p65 transfection. 15d-PGJ(2) treatment caused disruption of mitochondrial membrane potential, cytochrome c release, and caspase-3 activation, suggesting that 15d-PGJ(2) induces cell death through a mitochondria-dependent apoptotic mechanism. These changes by 15d-PGJ(2) were attenuated by NF-kappaB p65 transfection. 15d-PGJ(2) treatment resulted in an increase in Bax expression, which were blocked by NF-kappaB p65 transfection. 15d-PGJ(2) treatment caused PKA inhibition and 15d-PGJ(2)-induced cell death was enhanced by the PKA specific inhibitor H89. Inhibition of NF-kappaB by 15d-PGJ(2) was prevented by addition of forskolin, a PKA activator. Taken together, these results suggest that PKA-dependent NF-kappaB inhibition stimulates 15d-PGJ(2)-mediated mitochondrial apoptotic pathway through alterations in expression of the NF-kappaB target genes Bax.

Genetic control of gonadal development proceeds through either the male or female molecular pathways, driving bipotential gonadal anlage differentiation into a testis or ovary. Antagonistic interactions between the 2 pathways determine the gonadal sex. Essentially sex determination is the enhancement of one of the 2 pathways according to genetic sex. Initially, Sry with other factors upregulates Sox9 expression in XY individuals. Afterwards the expression of Sox9 is maintained by a positive feedback loop with Fgf9 and prostaglandin D2 as well as by autoregulative ability of Sox9. If these factors reach high concentrations, then Sox9 and/or Fgf9 may inhibit the female pathway. Surprisingly, splicing, nuclear transport, and extramatrix proteins may be involved in sex determination. The male sex determination pathway switches on the expression of genes driving Sertoli cell differentiation. Sertoli cells orchestrate testicular differentiation. In the absence of Sry, the predomination of the female pathway results in the realization of a robust genetic program that drives ovarian differentiation.

Prostaglandin (PG) D(2) exerts multiple actions through interaction with distinct receptors, DP1 and DP2. We have shown that PGD(2) induces the expression of heme oxygenase-1 (HO-1) in the retinal pigment epithelium (RPE) that is essential for survival of photoreceptors. HO-1 is a key enzyme in physiological heme degradation. Here, we explored the mechanism for the PGD(2)-mediated induction of HO-1 expression using ARPE-19 human RPE cells. ARPE-19 cells secrete PGD(2) and express DP2 mRNA, but not DP1 mRNA. Treatment with a DP2 agonist, 15(R)-15-methyl-PGD(2) or DK-PGD(2), increased HO-1 mRNA expression, and pretreatment with a DP2 antagonist, CAY10471, decreased the magnitude of the PGD(2)-mediated HO-1 induction. By contrast, either DP1 agonist or antagonist caused only marginal influence on HO-1 expression. Moreover, transient expression assays showed the DP2 agonist activated the HO-1-gene promoter in the enhancer-dependent manner. Thus, PGD(2) induces HO-1 mRNA expression through DP2 receptor, linking the PGD(2)-DP2 signaling with heme homeostasis.

The 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) is a cyclopentene PG generated from PGD(2). It is an endogenous ligand of the peroxisome proliferator-activated receptor-gamma that is primarily involved in adipocyte differentiation and lipid metabolism. Its anti-inflammatory actions have recently attracted considerable research attention, although the precise role and underlying mechanisms of these actions are largely unknown. In the present study, we focused on the inhibitory action of 15d-PGJ(2) on the chemokine MCP-1, which plays a key role in the initiation and progression of inflammation by recruiting inflammatory cells to lesion sites. We found that 15d-PGJ(2) suppressed MCP-1 transcription and protein secretion in IFN-gamma-stimulated brain astrocytes. The inhibitory effects of 15d-PGJ(2) on MCP-1 resulted from its actions on the transcription factors, AP-1 and specificity protein-1, which play key roles in IFN-gamma-induced MCP-1 expression in astrocytes. Of interest, the negative effects of 15d-PGJ(2) on AP-1/specificity protein-1 signaling and the resulting inhibition of MCP-1 expression were mediated by MAPK phosphatase (MKP)-1 activity, which was induced by 15d-PGJ(2) in a peroxisome proliferator-activated receptor-independent manner. Thus, our data demonstrate a novel anti-inflammatory mechanism of 15d-PGJ(2) involving MKP-1. Considering the importance of MCP-1 in inflammatory processes, our results suggest that 15d-PGJ(2) analogues may have therapeutic potential to attenuate inflammatory brain diseases by inducing MKP-1 expression.