PGF(2alpha), a prostanoid released by endothelial cells activated by hypoxia, is a chemoattractant candidate for neutrophil recruitment

The Effects of Negative Pressure Therapy on Hair Growth of Mouse Models

Negative pressure therapy (NPT) has been shown to facilitate wound healing and promote hair growth in a porcine model. However, there is a paucity of research on the impact of negative pressure on hair growth in murine models. Despite the ability of nude mice to develop hair follicles, the hair they produce is often flawed towing to genetically induced keratin disorders, rendering them a pertinent animal model for assessing hair regeneration. Therefore, this study aims to investigate the effects of negative pressure on hair follicle growth in a nude mouse model. To achieve this, a customized external tissue expansion device was developed to apply negative pressure to the dorsum of nude mice. The mice were subjected to several treatment courses consisting of 15 and 30 min of continuous negative pressure at 10 mmHg, which were repeated 5 and 10 times every other day until sacrifice. Dorsal skin samples were subsequently extracted from the suction and nonsuction areas. The sections were stained with various antibodies to assess the expression of SOX-9, LHX-2, Keratin-15, β-catenin, CD31, and vascular endothelial growth factor-A, and a TUNEL assay was used to analyze cell apoptosis. The results showed that the number of hair follicles and angiogenesis were significantly higher in the suction area than in the nonsuction area in all groups. Moreover, mice that received NPT for 15 min for 10 times had a higher hair follicle density than the other three groups. Immunofluorescence staining for LHX-2 and Keratin 15 further validated the results of these findings. In conclusion, this study demonstrated that negative pressure effectively promotes hair follicle growth and angiogenesis in nude mice through SOX-9- and LHX-2-mediated follicular regeneration and β-catenin-mediated hair follicle morphogenesis.

Specific prostaglandins are produced in the migratory cells and the surrounding substrate to promote Drosophila border cell migration

Introduction: A key regulator of collective cell migration is prostaglandin (PG) signaling. However, it remains largely unclear whether PGs act within the migratory cells or their microenvironment to promote migration. Here we use Drosophila border cell migration as a model to uncover the cell-specific roles of two PGs in collective migration. The border cells undergo a collective and invasive migration between the nurse cells; thus, the nurse cells are the substrate and microenvironment for the border cells. Prior work found PG signaling is required for on-time border cell migration and cluster cohesion. Methods: Confocal microscopy and quantitative image analyses of available mutant alleles and RNAi lines were used to define the roles of the PGE2 and PGF2α synthases in border cell migration. Results: We find that the PGE2 synthase cPGES is required in the substrate, while the PGF2α synthase Akr1B is required in the border cells for on-time migration. Akr1B acts in both the border cells and their substrate to regulate cluster cohesion. One means by which Akr1B may regulate border cell migration and/or cluster cohesion is by promoting integrin-based adhesions. Additionally, Akr1B limits myosin activity, and thereby cellular stiffness, in the border cells, whereas cPGES limits myosin activity in both the border cells and their substrate. Decreasing myosin activity overcomes the migration delays in both akr1B and cPGES mutants, indicating the changes in cellular stiffness contribute to the migration defects. Discussion: Together these data reveal that two PGs, PGE2 and PGF2α, produced in different locations, play key roles in promoting border cell migration. These PGs likely have similar migratory versus microenvironment roles in other collective cell migrations.

1,4-Diaryl-1,2,3-triazole neolignan-celecoxib hybrids inhibit experimental arthritis induced by zymosan

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes cartilage damage. Anti-inflammatories are widely used in the management of RA, but they can have side effects such as gastrointestinal and/or cardiovascular disorders. Studies published by our group showed that the synthesis of hybrid triazole analogs neolignan-celecoxib containing the substituent groups sulfonamide (L15) or carboxylic acid (L18) exhibited anti-inflammatory activity in an acute model of inflammation, inhibited expression of P-selectin related to platelet activation and did not induce gastric ulcer, minimizing the related side effects. In continuation, the present study evaluated the anti-inflammatory effects of these analogs in an experimental model of arthritis and on the functions of one of the important cells in this process, macrophages. Mechanical hyperalgesia, joint edema, leukocyte recruitment to the joint and damage to cartilage in experimental arthritis and cytotoxicity, spread of disease, phagocytic activity and nitric oxide (NO) and hydrogen peroxide production by macrophages were evaluated. Pre-treatment with L15 and L18 reduced mechanical hyperalgesia, joint edema and the influx of leukocytes into the joint cavity after different periods of the stimulus. The histological evaluation of the joint showed that L15 and L18 reduced cartilage damage and there was no formation of rheumatoid pannus. Furthermore, L15 and L18 were non-cytotoxic. The analogs inhibited the spreading, the production of NO and hydrogen peroxide. L15 decreased the phagocytosis. Therefore, L15 and L18 may be potential therapeutic prototypes to treat chronic inflammatory diseases such as RA.

Specific prostaglandins are produced in the migratory cells and the surrounding substrate to promote Drosophila border cell migration

A key regulator of collective cell migration is prostaglandin (PG) signaling. However, it remains largely unclear whether PGs act within the migratory cells or their microenvironment to promote migration. Here we use Drosophila border cell migration as a model to uncover the cell-specific roles of two PGs in collective migration. Prior work shows PG signaling is required for on-time migration and cluster cohesion. We find that the PGE2 synthase cPGES is required in the substrate, while the PGF2α synthase Akr1B is required in the border cells for on-time migration. Akr1B acts in both the border cells and their substrate to regulate cluster cohesion. One means by which Akr1B regulates border cell migration is by promoting integrin-based adhesions. Additionally, Akr1B limits myosin activity, and thereby cellular stiffness, in the border cells, whereas cPGES limits myosin activity in both the border cells and their substrate. Together these data reveal that two PGs, PGE2 and PGF2α, produced in different locations, play key roles in promoting border cell migration. These PGs likely have similar migratory versus microenvironment roles in other collective cell migrations.

Neuroaxonal and cellular damage/protection by prostanoid receptor ligands, fatty acid derivatives and associated enzyme inhibitors

Cellular and mitochondrial membrane phospholipids provide the substrate for synthesis and release of prostaglandins in response to certain chemical, mechanical, noxious and other stimuli. Prostaglandin D₂, prostaglandin E₂, prostaglandin F_2α, prostaglandin I₂ and thromboxane-A₂ interact with five major receptors (and their sub-types) to elicit specific downstream cellular and tissue actions. In general, prostaglandins have been associated with pain, inflammation, and edema when they are present at high local concentrations and involved on a chronic basis. However, in acute settings, certain endogenous and exogenous prostaglandins have beneficial effects ranging from mediating muscle contraction/relaxation, providing cellular protection, regulating sleep, and enhancing blood flow, to lowering intraocular pressure to prevent the development of glaucoma, a blinding disease. Several classes of prostaglandins are implicated (or are considered beneficial) in certain central nervous system dysfunctions (e.g., Alzheimer’s, Parkinson’s, and Huntington’s diseases; amyotrophic lateral sclerosis and multiple sclerosis; stroke, traumatic brain injuries and pain) and in ocular disorders (e.g., ocular hypertension and glaucoma; allergy and inflammation; edematous retinal disorders). This review endeavors to address the physiological/pathological roles of prostaglandins in the central nervous system and ocular function in health and disease, and provides insights towards the therapeutic utility of some prostaglandin agonists and antagonists, polyunsaturated fatty acids, and cyclooxygenase inhibitors.

Extracellular matrix-derived peptide stimulates the generation of endocrine progenitors and islet organoids from iPSCs

Induced pluripotent stem cells (iPSCs) have enormous potential in producing human tissues endlessly. We previously reported that type V collagen (COL5), a pancreatic extracellular matrix protein, promotes islet development and maturation from iPSCs. In this study, we identified a bioactive peptide domain of COL5, WWASKS, through bioinformatic analysis of decellularized pancreatic ECM (dpECM)-derived collagens. RNA-sequencing suggests that WWASKS induces the formation of pancreatic endocrine progenitors while suppressing the development of other types of organs. The expressions of hypoxic genes were significantly downregulated in the endocrine progenitors formed under peptide stimulation. Furthermore, we unveiled an enhancement of iPSC-derived islets' (i-islets) glucose sensitivity under peptide stimulation. These i-islets secrete insulin in a glucose responsive manner. They were comprised of α, β, δ, and γ cells and were assembled into a tissue architecture similar to that of human islets. Mechanistically, the peptide is able to activate the canonical Wnt signaling pathway, permitting the translocation of β-catenin from the cytoplasm to the nucleus for pancreatic progenitor development. Collectively, for the first time, we demonstrated that an ECM-derived peptide dictates iPSC fate toward the generation of endocrine progenitors and subsequent islet organoids.

Anti-inflammatory, ulcerogenic and platelet activation evaluation of novel 1,4-diaryl-1,2,3-triazole neolignan-celecoxib hybrids

This study reports the synthesis of novel neolignans-celecoxib hybrids and the evaluation of their biological activity. Analogs8-13(L13-L18) exhibited anti-inflammatory activity, inhibited glycoprotein expression (P-selectin) related to platelet activation, and were considered non- ulcerogenic in the animal model, even with the administration of 10 times higher than the dose used in reference therapy. In silico drug-likeness showed that the analogs are compliant with Lipinski's rule of five. A molecular docking study showed that the hybrids8-13(L13-L18) fitted similarly with celecoxib in the COX-2 active site. According to this data, it is possible to infer that extra hydrophobic interactions and the hydrogen interactions with the triazole core may improve the selectivity towards the COX-2 active site. Furthermore, the molecular docking study with P-selectin showed the binding affinity of the analogs in the active site, performing important interactions with amino acid residues such as Tyr 48. Whereas the P-selectin is a promising target to the design of new anti-inflammatory drugs with antithrombotic properties, a distinct butterfly-like structure of 1,4-diaryl-1,2,3-triazole neolignan-celecoxib hybrids synthesized in this work may be a safer alternative to the traditional COX-2 inhibitors.

Acid-Sensing Ion Channels: Expression and Function in Resident and Infiltrating Immune Cells in the Central Nervous System

Peripheral and central immune cells are critical for fighting disease, but they can also play a pivotal role in the onset and/or progression of a variety of neurological conditions that affect the central nervous system (CNS). Tissue acidosis is often present in CNS pathologies such as multiple sclerosis, epileptic seizures, and depression, and local pH is also reduced during periods of ischemia following stroke, traumatic brain injury, and spinal cord injury. These pathological increases in extracellular acidity can activate a class of proton-gated channels known as acid-sensing ion channels (ASICs). ASICs have been primarily studied due to their ubiquitous expression throughout the nervous system, but it is less well recognized that they are also found in various types of immune cells. In this review, we explore what is currently known about the expression of ASICs in both peripheral and CNS-resident immune cells, and how channel activation during pathological tissue acidosis may lead to altered immune cell function that in turn modulates inflammatory pathology in the CNS. We identify gaps in the literature where ASICs and immune cell function has not been characterized, such as neurotrauma. Knowledge of the contribution of ASICs to immune cell function in neuropathology will be critical for determining whether the therapeutic benefits of ASIC inhibition might be due in part to an effect on immune cells.

Neutrophil-Induced Liver Injury and Interactions Between Neutrophils and Liver Sinusoidal Endothelial Cells

Neutrophils are the most abundant type of leukocytes with diverse functions in immune defense including production of reactive oxygen species, bacteriocidal proteins, neutrophil extracellular traps, and pro-inflammatory mediators. However, aberrant accumulation of neutrophils in host tissues and excessive release of bacteriocidal compounds can lead to unexpected injury to host organs. Neutrophil-mediated liver injury has been reported in various types of liver diseases including liver ischemia/reperfusion injury, nonalcoholic fatty liver disease, endotoxin-induced liver injury, alcoholic liver disease, and drug-induced liver injury. Yet the mechanisms of neutrophil-induced hepatotoxicity in different liver diseases are complicated. Current knowledge of these mechanisms are summarized in this review. In addition, a substantial body of evidence has emerged showing that liver sinusoidal endothelial cells (LSECs) participate in several key steps of neutrophil-mediated liver injury including neutrophil recruitment, adhesion, transmigration, and activation. This review also highlights the current understanding of the interactions between LSECs and neutrophils in liver injury. The future challenge is to explore new targets for selectively interfering neutrophil-induced liver injury without impairing host defense function against microbial infection. Further understanding the role of LSECs in neutrophil-induced hepatotoxicity would aid in developing more selective therapeutic approaches for liver disease.

Treatment for Hepatocellular Carcinoma Is Enhanced When Norcantharidin Is Encapsulated in Exosomes Derived from Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem cell-derived exosomes (MSC-Exos) have potential as drug-delivery vehicles and exhibit great promise for hepatocellular carcinoma (HCC) therapy. Here, we consider bone mesenchymal stem cell-derived exosomes (BMSC-Exos) as drug carriers to encase anticancer drug norcantharidin (NCTD) and explore their potential therapeutic effects against HCC. NCTD was loaded into purified exosomes from BMSCs via electroporation, and an in vitro drug release study showed that BMSC-Exos-NCTD provided a continuous and slow release of the drug. A series of in vitro and in vivo pharmacodynamic evaluations based on the HCC cell line HepG2 were conducted. The results showed that the BMSC-Exos-NCTD delivery system effectively promoted cellular uptake, induced cell cycle arrest, reduced tumor cell proliferation, increased apoptosis, and exerted obvious in vivo antitumor effects compared with the NCTD treatment alone, with BMSC-Exos-NCTD showing more significant antitumor effects. Furthermore, the in vivo detection results of the homing effect using the probe Cy5.5 showed that the BMSC-Exos carrier has an in situ homing effect on the tumor sites of HCC in mice. Moreover, BMSC-Exos-NCTD did not show body toxicity. Excitedly, BMSC-Exos-NCTD repaired damaged liver tissues in liver sections; specifically, the experimental effectiveness of the exosomes on the normal liver cell line L02 indicated that the damaged liver cells were repaired by the exosomes, as reflected by the increase in cellular proliferation and the inhibition of liver cell oxidation. Our results suggest that BMSC-Exos, as drug carriers with specific functions, have great potential in the HCC treatment in combination with anticancer drugs.

Leishmania braziliensis prostaglandin F2α synthase impacts host infection

Background

Prostaglandins (PG) are lipid mediators derived from arachidonic acid metabolism. They are involved in cellular processes such as inflammation and tissue homeostasis. PG production is not restricted to multicellular organisms. Trypanosomatids also synthesize several metabolites of arachidonic acid. Nevertheless, their biological role in these early-branching parasites and their role in host-parasite interaction are not well elucidated. Prostaglandin F_2α synthase (PGF2S) has been observed in the Leishmania braziliensis secreted proteome and in L. donovani extracellular vesicles. Furthermore, we previously reported a positive correlation between L. braziliensis PGF2S (LbrPGF2S) expression and pathogenicity in mice.

Methods

LbrPGF2S gene expression and PGF2α synthesis in promastigotes were detected and quantified by western blotting and EIA assay kit, respectively. To investigate LbrPGF2S localization in amastigotes during bone marrow-derived macrophage infection, parasites expressing mCherry-LbrPGF2S were generated and followed by time-lapse imaging for 48 h post-infection. PGF2S homolog sequences from Leishmania and humans were analyzed in silico using ClustalW on Geneious v6 and EMBOSS Needle.

Results

Leishmania braziliensis promastigotes synthesize prostaglandin F_2α in the presence of arachidonic acid, with peak production in the stationary growth phase under heat stress. LbrPGF2S is a cytoplasmic protein enriched in the secretory site of the parasite cell body, the flagellar pocket. It is an enzyme constitutively expressed throughout promastigote development, but overexpression of LbrPGF2S leads to an increase of infectivity in vitro. The data suggest that LbrPGF2S may be released from intracellular amastigotes into the cytoplasm of bone marrow-derived macrophages over a 48-hour infection period, using time-lapse microscopy and mCherry-PGF2S (mChPGF2S)-expressing parasites.

Conclusions

LbrPGF2S, a parasite-derived protein, is targeted to the host cell cytoplasm. The putative transfer of this enzyme, involved in pro-inflammatory lipid mediator synthesis, to the host cell suggests a potential role in host-parasite interaction and may partially explain the increased pathogenicity associated with overexpression of LbrPGF2S in L. braziliensis. Our data provide valuable insights to help understand the importance of parasite-derived lipid mediators in pathogenesis.

First exploratory study on the metabolome from plasma exosomes in patients with paroxysmal nocturnal hemoglobinuria

INTRODUCTION

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease in which patients are at increased risk of thrombosis. The mechanisms underlying the associated thrombosis risk are still poorly understood, although it is known that Eculizumab, the drug of choice for symptomatic patients, prevents thrombotic events. Exosomes are extracellular vesicles that can carry and disseminate genetic material, tumor biomarkers and inflammatory mediators. To date, the metabolite cargo of plasma exosomes from PNH patients has not yet been explored. In this pilot trial, we compared the metabolome of plasma exosomes from PNH patients with that of healthy subjects in order to provide further insights into this rare disease.

RESULTS

We used a non-targeted metabolomics approach with UPLC-ESI-QTOF-MS/MS and GC-MS platforms. Multivariate analyses revealed the differential occurrence (p < .001) of 78 metabolites in plasma exosomes from PNH patients vs healthy control subjects. Remarkably, prostaglandin F2-alpha (6.1-fold), stearoyl arginine (5.3-fold) and 26-hydroxycholesterol-3-sulfate (11.2-fold) were higher in PNH patients vs healthy controls (p < .001).

CONCLUSIONS

This is the first description on the differential metabolite cargo occurring in plasma exosomes from PNH patients. Our results could contribute to the search for possible prognostic biomarkers of thrombotic risk in patients with PNH. Further research in a larger cohort to validate these results is warranted.

Unravelling the Interplay between Extracellular Acidosis and Immune Cells

The development of an acidic tissue environment is a hallmark of a variety of inflammatory processes and solid tumors. However, little attention has been paid so far to analyze the influence exerted by extracellular pH on the immune response. Tissue acidosis (pH 6.0 to 7.0) is usually associated with the course of infectious processes in peripheral tissues. Moreover, it represents a prominent feature of solid tumors. In fact, values of pH ranging from 5.7 to 7.0 are usually found in a number of solid tumors such as breast cancer, brain tumors, sarcomas, malignant melanoma, squamous cell carcinomas, and adenocarcinomas. Both the innate and adaptive arms of the immune response appear to be finely regulated by extracellular acidosis in the range of pH values found at inflammatory sites and tumors. Low pH has been shown to delay neutrophil apoptosis, promoting their differentiation into a proangiogenic profile. Acting on monocytes and macrophages, it induces the activation of the inflammasome and the production of IL-1β, while the exposure of conventional dendritic cells to low pH promotes the acquisition of a mature phenotype. Overall, these observations suggest that high concentrations of protons could be recognized by innate immune cells as a danger-associated molecular pattern (DAMP). On the other hand, by acting on T lymphocytes, low pH has been shown to suppress the cytotoxic response mediated by CD8+ T cells as well as the production of IFN-γ by TH1 cells. Interestingly, modulation of tumor microenvironment acidity has been shown to be able not only to reverse anergy in human and mouse tumor-infiltrating T lymphocytes but also to improve the antitumor immune response induced by checkpoint inhibitors. Here, we provide an integrated view of the influence exerted by low pH on immune cells and discuss its implications in the immune response against infectious agents and tumor cells.

Prostaglandin FP receptor antagonists: discovery, pharmacological characterization and therapeutic utility

In contrast to the availability of potent and selective antagonists of several prostaglandin receptor types (including DP₁ , DP₂ , EP and TP receptors), there has been a paucity of well-characterized, selective FP receptor antagonists. The earliest ones included dimethyl amide and dimethyl amine derivatives of PGF_2α , but these have failed to gain prominence. The fluorinated PGF_2α analogues, AL-8810 and AL-3138, were subsequently discovered as competitive and non-competitive FP receptor antagonists respectively. Non-prostanoid structures, such as the thiazolidinone AS604872, the D-amino acid-based oligopeptide PDC31 and its peptidomimic analogue PDC113.824 came next, but the latter two are allosteric inhibitors of FP receptor signalling. AL-8810 has a sub-micromolar in vitro potency and ≥2 log unit selectivity against most other PG receptors when tested in several cell- and tissue-based functional assays. Additionally, AL-8810 has demonstrated therapeutic efficacy as an FP receptor antagonist in animal models of stroke, traumatic brain injury, multiple sclerosis, allodynia and endometriosis. Consequently, it appears that AL-8810 has become the FP receptor antagonist of choice. LINKED ARTICLES: This article is part of a themed section on Eicosanoids 35 years from the 1982 Nobel: where are we now? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.8/issuetoc.

Prostanoids in the pathophysiology of human coronary artery

Coronary artery disease is one of the leading causes of death in wordwide. There is growing evidence that prostanoids are involved in the physiology and pathophysiology of the human coronary artery by controlling vascular tone, remodelling of the vascular wall or angiogenesis. In this review, the production of prostanoids and the expression of prostanoid receptors in human coronary artery in health or disease are described. In addition, the interactions between sex hormones and prostanoids, their participations in the development of coronary artery diseases have been addressed. Globally, most of the studies performed in human coronary artery preparations have shown that prostacyclin (PGI₂) has beneficial effects by inducing vasodilatation and promoting angiogenesis while reverse effects are confirmed by thromboxane A₂ (TxA₂). More studies are needed to determine the roles of the other prostanoids (PGE₂, PGD₂ and PGF_2α) in vascular functions of the human coronary artery. Finally, in addition to the in vitro data about the human coronary artery, myocardial infarction induced by cyclooxygenase-2 (COX-2) inhibitor and the protective effects of aspirin after coronary artery bypass surgery suggest that prostanoids are key mediators in coronary homeostasis.

Extracellular Acidification Inhibits the ROS-Dependent Formation of Neutrophil Extracellular Traps

The inflammatory microenvironment is commonly characterized by extracellular acidosis (pH < 7.35). Sensitivity to pH, CO₂ or bicarbonate concentrations allows neutrophils to react to changes in their environment and to detect inflamed areas in the tissue. One important antimicrobial effector mechanism is the production of neutrophil extracellular traps (NETs), which are released during a programmed reactive oxygen species (ROS)-dependent cell death, the so-called NETosis. Although several functions of neutrophils have been analyzed under acidic conditions, the effect of extracellular acidosis on NETosis remains mainly unexplored and the available experimental results are contradictory. We performed a comprehensive study with the aim to elucidate the effect of extracellular acidosis on ROS-dependent NETosis of primary human neutrophils and to identify the underlying mechanisms. The study was performed in parallel in a CO₂–bicabonate-buffered culture medium, which mimics in vivo conditions, and under HEPES-buffered conditions to verify the effect of pH independent of CO₂ or bicarbonate. We could clearly show that extracellular acidosis (pH 6.5, 6.0, and 5.5) and intracellular acidification inhibit the release of ROS-dependent NETs upon stimulation of neutrophils with phorbol myristate acetate and immobilized immune complexes. Moreover, our findings suggest that the diminished NET release is a consequence of reduced ROS production and diminished glycolysis of neutrophils under acidic conditions. It was suggested previously that neutrophils can sense the border of inflamed tissue by the pH gradient and that a drop in pH serves as an indicator for the progress of inflammation. Following this hypothesis, our data indicate that an acidic inflammatory environment results in inhibition of extracellular operating effector mechanisms of neutrophils such as release of ROS and NETs. This way the release of toxic components and tissue damage can be avoided. However, we observed that major antimicrobial effector mechanisms such as phagocytosis and the killing of pathogens by neutrophils remain functional under acidic conditions.

The Effects of Negative Pressure by External Tissue Expansion Device on Epithelial Cell Proliferation, Neo-Vascularization and Hair Growth in a Porcine Model

While pre-treating a fat transplant recipient site with negative pressure has shown promise for increasing the fat survival rate, the underlying mechanisms have not been investigated, partly due to challenges related to immobilization of vacuum domes on large animal subjects. The aim of this study was to examine the effect of negative pressure treatment by External Tissue Expansion Device (ETED) on fat grating recipient sites in a porcine model. The ETED was designed to provide negative pressure on the dorsum of swine. Pressure treatment (-70 mmHg) was applied for 1 or 3 hours every other day for 10 and 20 treatments. The treated areas (3.5 cm in diameter) were harvested and examined for histological changes, vessel density, cell proliferation (Ki67) and growth factor expression (FGF-1, VEGF and PDGB-bb). The application of the ETED increased epidermis thickness even after 1-hour treatments repeated 10 times. The results of Ki67 analysis suggested that the increasing thickness was due to cell proliferation in the epidermis. There was a more than two-fold increase in the vessel density, indicating that the ETED promotes vascularization. Unexpectedly, the treatment also increased the number of hair follicles. Negative pressure provided by the ETED increases the thickness of epidermis section of tissue, cell proliferation and vessel density. The porcine model provides a better representation of the effect of the ETED on skin tissue compared to small animal models and provides an environment for studying the mechanisms underlying the clinical benefits of negative pressure treatment.

Mesenchymal stem cell exosomes

MSCs are an extensively used cell type in clinical trials today. The initial rationale for their clinical testing was based on their differentiation potential. However, the lack of correlation between functional improvement and cell engraftment or differentiation at the site of injury has led to the proposal that MSCs exert their effects not through their differentiation potential but through their secreted product, more specifically, exosomes, a type of extracellular vesicle. We propose here that MSC exosomes function as an extension of MSC's biological role as tissue stromal support cells. Like their cell source, MSC exosomes help maintain tissue homeostasis for optimal tissue function. They target housekeeping biological processes that operate ubiquitously in all tissues and are critical in maintaining tissue homeostasis, enabling cells to recover critical cellular functions and begin repair and regeneration. This hypothesis provides a rationale for the therapeutic efficacy of MSCs and their secreted exosomes in a wide spectrum of diseases. Here, we give a brief introduction of the biogenesis of MSC exosomes, review their physiological functions and highlight some of their biochemical potential to illustrate how MSC exosomes could restore tissue homeostasis leading to tissue recovery and repair.

Development of oxidative stress and cell damage in the liver of rats with water-immersion restraint stress

We examined how oxidative stress and cell damage develop in the liver of rats subjected to water-immersion stress (WIRS). In rats subjected to WIRS for 1.5, 3 or 6 h, serum alanine aminotransferase and aspartate aminotransferase activities increased time-dependently. In the liver tissue, vacuolization and apoptosis occurred at 1.5 h of WIRS and vacuolization further developed without further appearance of apoptosis at 3 h or 6 h. Serum lipid peroxide (LPO) and NOx (nitrite/nitrate) concentrations increased at 3 h of WIRS and these increases were enhanced at 6 h. In liver tissue, increases in LPO and NOx concentrations and myeloperoxidase activity and decreases in ascorbic acid and reduced glutathione concentrations and superoxide dismutase activity occurred at 3 h of WIRS and these changes were enhanced at 6 h, although vitamin E concentration and xanthine oxidase activity were unchanged. These results indicate that oxidative stress in the liver of rats with WIRS develops after the appearance of cell damage in the tissue, and suggests that oxidative stress is caused through disruption of the antioxidant defense system and increases in NO generation and neutrophil infiltration in the liver, which may contribute to the progression of cell damage in the tissue.

Extracellular acidosis modulates the endocytosis and maturation of macrophages

Extracellular acidosis is involved in various pathological situations of central nervous system and the effects are largely mediated by acid sensing ion channels (ASICs). However, it remains unclear whether extracellular acidosis affects immune cells. Macrophages are immune cells that play important role in immune reactions. In this study we investigated the impact of extracellular acidosis on the function of bone marrow derived macrophages (BMMs). The results showed that extracellular acidosis upregulated the endocytosis, surface molecular expression and interleukin-10 secretion of BMMs, in which the expression of ASIC1 and ASIC3 was detected. Notably, extracellular acidosis stimulated endocytosis and upregulation of surface molecules expression in BMMs could be abolished by amiloride, a blocker of ASICs, and nonsteroid anti-inflammatory drugs. Our findings provide new insight into the role of extracellular acidosis in the regulation of immune function and suggest ASICs as new targets for the modulation of immune response.

Low extracellular pH stimulates the production of IL-1β by human monocytes

The development of acidic environments is a hallmark of inflammatory processes of different etiology. We have previously shown that transient exposure to acidic conditions, similar to those encountered in vivo, induces the activation of neutrophils and the phenotypic maturation of dendritic cells. We here report that extracellular acidosis (pH 6.5) selectively stimulates the production and the secretion of IL-1β by human monocytes without affecting the production of TNF-α, IL-6 and the expression of CD40, CD80, CD86, and HLA-DR. Stimulation of IL-1β production by pH 6.5-treated monocytes was shown to be dependent on caspase-1 activity, and it was also observed using peripheral blood mononuclear cells instead of isolated monocytes. Contrasting with the results in monocytes, we found that pH 6.5 did not stimulate any production of IL-1β by macrophages. Changes in intracellular pH seem to be involved in the stimulation of IL-1β production. In fact, monocytes cultured at pH 6.5 undergo a fall in the values of intracellular pH while the inhibitor of the Na+/H+ exchanger, 5-(N-ethyl-N-isopropyl)amiloride induced both, a decrease in the values of intracellular pH and the stimulation of IL-1β production. Real time quantitative PCR assays indicated that monocytes cultured either at pH 6.5 or in the presence of 5-(N-ethyl-N-isopropyl)amiloride expressed higher levels of pro-IL-1β mRNA suggesting that low values of intracellular pH enhance the production of IL-1β, at least in part, by stimulating the synthesis of its precursor.

The influence of topical prostaglandin analogues in inflammation after selective laser trabeculoplasty treatment

PURPOSE

Reducing intraocular pressure (IOP) seems to be the only treatment that slows progression in glaucoma. The IOP can be decreased by pharmaceutical treatment, laser [selective laser trabeculoplasty (SLT)] treatment, or surgery. Prostaglandin analogues have been postulated to share action mechanisms with SLT and to possibly diminish the effects of SLT treatment. The aim of the current study was to investigate the effects of prostaglandin analogues in inflammation and IOP reduction after SLT treatment.

METHODS

Prospective nonrandomized study. One hundred and eighteen patients were included in the study.

INCLUSION CRITERIA

Glaucoma (open-angle or pseudoexfoliation glaucoma) patients who will be treated with SLT. Inflammation was measured with a laser flare meter (Kowa FM-500). Measurements were made before SLT and then 2 h, 1 week, and 1 month after SLT treatment. IOP was also checked at the same time intervals. The SLT treatment was performed over 90°. All patients were divided into two groups: those receiving prostaglandins analogues and those treated with nonprostaglandin analogues.

RESULTS

Inflammation before and after SLT showed no significant difference between the groups at all the time intervals studied (t-test, before: P=0.16; 2 h: P=0.14; 1 week: P=0.12; and 1 month: P=0.36). IOP reduction showed no significant difference between the groups (t-test, P=0.31).

CONCLUSIONS

SLT treatment effects do not seem to be influenced by the use of prostaglandin analogues.

Hepatocyte growth factor induces hypoxia-related interleukin-8 expression in lung adenocarcinoma cells

Rapid growth of cancer cells often creates insufficient supply of oxygen and nutrients in the tumour nest. The frequent detection of hypoxia-inducible factor (HIF) and interleukin-8 (IL-8) in afflicted tissues suggests that IL-8 expression could be associated with elevated levels of HIF. Recently, we found that hypoxia also upregulated the expression of hepatocyte growth factor (HGF) in lung adenocarcinoma (LAD) cells. However, the relationship between HGF and IL-8 has not been investigated in LAD cells. In this study, we found that HGF induced IL-8 expression in LAD. Interestingly, hypoxia also increased the level of prostaglandin F(2alpha) (PGF(2alpha)), a product of dihydrodiol dehydrogenase (DDH). When expression of DDH was suppressed by siRNA, the levels of PGF(2alpha), HGF and IL-8 were reduced; however, their levels returned to normal after DDH was reintroduced. These data suggest that hypoxia induces biosynthesis of PGF(2alpha), which then activates HGF and IL-8 expression. The results provide a reasonable explanation of how PGF(2alpha), HGF and IL-8 exert their effects on cancer cell metastasis.

Lysophosphatidic acid stimulates prostaglandin E2 production in cultured stromal endometrial cells through LPA1 receptor

Lysophosphatidic acid (LPA) has been shown to be a potent modulator of prostaglandin (PG) secretion during the luteal phase of the estrous cycle in the bovine endometrium in vivo. The aims of the present study were to determine the cell types of the bovine endometrium (epithelial or stromal cells) responsible for the secretion of PGs in response to LPA, the cellular, receptor, intracellular, and enzymatic mechanisms of LPA action. Cultured bovine epithelial and stromal cells were exposed to LPA (10(-5)-10(-9) M), tumor necrosis factor alpha (TNFalpha; 10 ng/mL) or oxytocin (OT; 10(-7) M) for 24 h. LPA treatment resulted in a dose-dependent increase of PGE(2) production in stromal cells, but not in epithelial cells. LPA did not influence PGF(2alpha) production in stromal or epithelial cells. To examine which type of LPA G-protein-coupled receptor (LP-GPCR; LPA1, LPA2, or LPA3) is responsible for LPA action, stromal cells were preincubated with three selected blockers of LPA receptors: NAEPA, DGPP, and Ki16425 for 0.5 h, and then stimulated with LPA. Only Ki16425 inhibited the stimulatory effect of LPA on PGE(2) production and cell proliferation in the stromal cells. LPA-induced intracellular calcium ion mobilization was also inhibited only by Ki16425. Finally, we examined whether LPA-induced PGE(2) synthesis in stromal cells is via the influence on mRNA expression for the enzymes responsible for PGE(2) synthesis-PGE(2) synthase (PGES) and PG-endoperoxide synthase 2 (PTGS2). We demonstrated that the stimulatory effect of LPA on PGE(2) production in stromal cells is via the stimulation of PTGS2 and PGES mRNA expression in the cells. The overall results indicate that LPA stimulates PGE(2) production, cell viability, and intracellular calcium ion mobilization in cultured stromal endometrial cells via Ki16425-sensitive LPA1 receptors. Moreover, LPA exerts a stimulatory effect on PGE(2) production in stromal cells via the induction of PTGS2 and PGES mRNA expression.

How might we achieve oxygen balance in wounds?

This paper describes the mechanism and physiological relevance of a new kind of oxygenating wound care technology, designed to deliver 'oxygen balance'. It provides a continuous, controlled delivery of dissolved oxygen over an appropriate time scale, at the same time as providing all the required basics of wound care. Even though it is initially perceived as a simple dressing, it is an advanced, active biochemical process contained in a dressing structure, using the enzyme glucose oxidase to capture and transport oxygen from the atmosphere. With this technology, it is proposed that oxygen balance can be defined by relating the levels of achievable oxygenation to the cellular and biochemical activities required to bring about optimal wound healing.

Extracellular acidosis triggers the maturation of human dendritic cells and the production of IL-12

Although the development of an acidic tissue environment or acidosis is a hallmark of inflammatory processes, few studies analyze the effect of extracellular pH on immune cells. We have previously shown that exposure of murine dendritic cells (DCs) to pH 6.5 stimulates macropinocytosis and cross-presentation of extracellular Ags by MHC class I molecules. We report that the transient exposure of human DCs to pH 6.5 markedly increases the expression of HLA-DR, CD40, CD80, CD86, CD83, and CCR7 and improves the T cell priming ability of DCs. Incubation of DCs at pH 6.5 results in the activation of the PI3K/Akt and the MAPK pathways. Using specific inhibitors, we show that the maturation of DCs induced by acidosis was strictly dependent on the activation of p38 MAPK. DC exposure to pH 6.5 also induces a dramatic increase in their production of IL-12, stimulating the synthesis of IFN-gamma, but not IL-4, by Ag-specific CD4(+) T cells. Interestingly, we find that suboptimal doses of LPS abrogated the ability of pH 6.5 to induce DC maturation, suggesting a cross-talk between the activation pathways triggered by LPS and extracellular protons in DCs. We conclude that extracellular acidosis in peripheral tissues may contribute to the initiation of adaptive immune responses by DCs, favoring the development of Th1 immunity.

Modulation of human airway smooth muscle migration by lipid mediators and Th-2 cytokines

Cysteinyl leukotrienes and the T helper (Th)-2 cytokines IL-5 and IL-13 directly modulate human airway smooth muscle functions such as contraction and proliferation. We studied the effects of other lipid mediators involved in asthma pathophysiology such as prostaglandin D(2) (PGD(2)), lipoxin, and isoprostanes, and the cytokines, IL-5, IL-4, and IL-13 on human airway smooth muscle cell migration. Chemotaxis and chemokinesis of cultured airway smooth muscle cells from humans without asthma (second to fifth passages, n = 6) were studied using collagen-I-coated polycarbonate membranes in Transwell culture plates. Receptor expression and kinase activation were studied by flow cytometry, polymerase chain reaction, and Western blotting techniques. In contrast to LTE(4)- stimulated (10(-6) M) chemokinesis and LTE(4)-primed migration toward platelet-derived growth factor (PDGF), isoprostane 15-F(2t)-IsoP, and IL-5 were neither chemotactic nor chemokinetic. PGD(2) (10(-10)-10(-6) M) was a chemoattractant and primed migration toward PDGF through the DP(2)/CRTh(2) receptor. Although airway smooth muscle cells did not express the lipoxin A(4) cognate receptor, LTE(4)-primed migration toward PDGF was blocked by lipoxin A(4) (10(-6) M), suggesting that this is mediated through CysLT(1)R antagonism. IL-13 (10 ng/ml), but not IL-4 (0.1-100 ng/ml), augmented migration toward PDGF. This was associated with increased Src-kinase phosphorylation and up-regulation of PDGF-alpha and -beta receptors, and was attenuated by IL-13Ralpha- and IL-4Ralpha-neutralizing antibodies, an Src-kinase antagonist (PP1, 3 muM), a CysLT(1)R antagonist, montelukast (10(-6) M), and by lipoxin A(4) (10(-6) M). PGD(2) and IL-13 promote human airway smooth muscle migration. IL-13 can promote airway smooth muscle migration through Src-kinase and leukotriene-dependent pathways. This may contribute to the accumulation of smooth muscle cells in remodeled airway submucosa.

Inhibition of prostaglandin F(2alpha) by selective cyclooxygenase 2 inhibitors accounts for reduced rat leukocyte migration

To investigate whether selective COX 2 inhibitors (celecoxib, rofecoxib) would play a role in a model of leukocyte migration in rats. Bacterial endotoxin (Escherichia coli LPS) was intraperitoneally injected at time zero in rats that were previously treated with unspecific and selective cyclooxygenase inhibitors. LPS induced a dose and time-dependent increase in leukocyte number, which was predominantly related to the presence of PMN neutrophils. Only rats treated with selective COX 2 inhibitors and indomethacin showed a significant reduction in leukocyte numbers following LPS administration. Prostaglandins E(2) and F(2alpha) were injected into the peritoneum and the chemoatractant effect was studied. Only PGF(2alpha) was able to induce neutrophil increase following injection. Intraperitoneal reposition of PGF(2alpha) restored the abrogated leukocyte response to LPS, shown by rats pretreated with rofecoxib. It can be concluded that COX 2, through PGF(2alpha) release, is the isoform responsible for neutrophil recruitment in the rat model of LPS-induced inflammation.

Prostaglandin F2alpha Upregulates Uterine Immune Defenses in the Presence of the Immunosuppressive Steroid Progesterone

PROBLEM

Uterine infections often develop in some livestock species during the first luteal phase postpartum. Exogenous prostaglandin F(2alpha) (PGF(2alpha)) induces luteolysis, reduces progesterone, and enables the uterus to resolve infections. However, the effects of PGF(2alpha) on luteal function and on immune functions are confounded. These effects must be disentangled to determine whether alternatives to antibiotic treatments can be successfully developed.

METHOD OF STUDY

Treatments were in a 2 x 2 x 2 factorial arrangement. Main effects were ovariectomy or sham on day 0 (i.e. estrus), exogenous progesterone or sesame oil from day 0 to 11, and exogenous PGF(2alpha) or saline on day 9. Intrauterine inoculations with Arcanobacterium pyogenes and Escherichia coli were administered on day 6.

RESULTS

Ewes treated with exogenous PGF(2alpha) either did not have uterine infections, infections were less severe, or infections were resolving when uteri were examined on day 12, despite increased progesterone.

CONCLUSIONS

Exogenous PGF(2alpha) has effects on the resolution of uterine infections that are independent of its effects on luteal progesterone production.

An unexpected negative inotropic effect of prostaglandin F2alpha in the rat heart

Prostaglandin F(2alpha) (PGF(2alpha)) is produced during myocardial inflammation and many of the insults that trigger contractile dysfunction also activate prostaglandin synthesis and production. However, although PGF(2alpha) plays a significant role in the cardiac response to inflammation, the effect of this particular compound on the heart was largely studied at the cellular level and probably no due attention was paid to the effect of PGF(2alpha) on the whole heart contractility. Therefore, in the present study we have investigated the effect of PGF(2alpha) on isolated right ventricle of the rat heart. PGF(2alpha) (1nM-1microM) induced concentration-dependent decrease of the amplitude of contractions of the ventricular muscle. Real time RT-PCR has revealed that prostaglandin FP receptors are expressed in the rat myocardium and the level of expression was similar to those of creatine kinase and adenylate kinase, which are proteins abundantly present in the heart. An antagonist of FP receptors, PGF(2alpha) dimetilamide (10nM), abolished negative inotropic effect induced by PGF(2alpha). To examine the possibility that PGF(2alpha) could activate non-FP prostaglandin receptor, we have measured the level of expression of all known prostaglandin receptors in the rat heart. These experiments have shown that the order of expression of prostaglandin receptors in the rat heart is FP>>EP1=TP>EP4>EP3>DP=IP. Based on the obtained results we conclude that PGF(2alpha) induces negative inotropic effect on rat heart by activating FP prostaglandin receptors. This effect of PGF(2alpha) could contribute to cardiac dysfunction in conditions of systemic and myocardial inflammation.

Extracellular acidosis induces neutrophil activation by a mechanism dependent on activation of phosphatidylinositol 3-kinase/Akt and ERK pathways

Inflammation in peripheral tissues is usually associated with the development of local acidosis; however, there are few studies aimed at analyzing the influence of acidosis on immune cells. We have shown previously that extracellular acidosis triggers human neutrophil activation, inducing a transient increase in intracellular Ca2+ concentration, a shape change response, the up-regulation of CD18 expression, and a delay of apoptosis. In this study, we analyzed the signaling pathways responsible for neutrophil activation. We found that acidosis triggers the phosphorylation of Akt (the main downstream target of PI3K) and ERK MAPK, but not that of p38 and JNK MAPK. No degradation of IkappaB was observed, supporting the hypothesis that NF-kappaB is not activated under acidosis. Inhibition of PI3K by wortmannin or LY294002 markedly decreased the shape change response and the induction of Ca2+ transients triggered by acidosis, whereas the inhibition of MEK by PD98059 or U0126 significantly inhibited the shape change response without affecting the induction of Ca2+ transients. We also found that acidosis not only induces a shape change response and the induction of Ca2+ transients in human neutrophils but also stimulates the endocytosis of FITC-OVA and FITC-dextran. Stimulation of endocytosis was partially prevented by inhibitors of PI3K and MEK. Together, our results support the notion that the stimulation of human neutrophils by extracellular acidosis is dependent on the activation of PI3K/Akt and ERK pathways. Of note, using mouse peritoneal neutrophils we observed that the enhancement of endocytosis induced by acidosis was associated with an improved ability to present extracellular Ags through a MHC class I-restricted pathway.

Crystalline and amorphous silica differentially regulate the cyclooxygenase-prostaglandin pathway in pulmonary fibroblasts: implications for pulmonary fibrosis

Inhalation of crystalline (CS) and amorphous silica (AS) results in human pulmonary inflammation. However, silicosis develops only following CS exposure, and the pathogenic mechanisms are poorly understood. This report describes the differential abilities of CS and AS to directly upregulate the early inflammatory mediator COX-2, the recently identified prostaglandin E (PGE) synthase and the downstream mediator PGE2 in primary human lung fibroblasts. Increased cyclooxygenase (COX)-2 gene transcription and protein production were demonstrated by ribonuclease protection assay, Western blot analysis, and immunocytochemistry. In each case the ability of AS to induce COX-2 exceeded that of CS. Similarly, downstream of COX-2, production of the antifibrotic prostaglandin PGE2 was induced in a dose-dependent fashion, but AS was significantly more potent (maximal production: CS = 4,710 pg/ml and AS = 7,651 pg/ml). These increases in COX-2 and PGE2 were preceded by induction of the PGE2 synthase protein, demonstrating the potential role of this novel molecule in silica-mediated inflammation. There was specificity of induction of prostaglandins, as PGF2alpha, but not PGD2, was induced. Using specific COX-2 inhibitors, we showed increased PG production to be dependent on the COX-2 enzyme. Furthermore, stimulation of fibroblasts was particle specific, as silica but not carbon black resulted in fibroblast activation. These results demonstrate that silica can directly stimulate human lung fibroblasts to produce key inflammatory enzymes and prostaglandins. Moreover, they suggest a mechanism to explain the differing fibrogenic potential of CS and AS. The molecules COX-2, PGE synthase, and PGE2 are identified as effectors in silicosis.

Role of Cl− currents in rat aortic smooth muscle activation by prostaglandin F2α

The aim of this study was to determine the role of Cl(-) channel activation in prostaglandin F(2 alpha)-stimulated aortic contraction and in membrane depolarization during stimulation with prostaglandin F(2 alpha) in an aortic smooth muscle cell line (A7r5). The Cl(-) channel antagonists 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), indanyloxyacetic acid-94 (IAA-94) and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) were found to decrease (P<0.05) the maximum tension generated by rat thoracic aortic segments during stimulation with prostaglandin F(2 alpha) and to shift the concentration-response relationship to the right. In the presence of Nifedipine and Cesium, rat aorta-derived A7r5 smooth muscle cells demonstrated outwardly rectifying voltage-dependent currents that were inhibited by NPPB, IAA-94 and DIDS. Both inward and outward currents were enhanced (P<0.05) following addition of prostaglandin F(2 alpha) (4 micromol/l, final concentration) to the bath solution and this increase was completely inhibited by NPPB. In the absence of Cesium, the addition of prostaglandin F(2 alpha) (4 micromol/l) to the extracellular bath solution either depolarized or hyperpolarized the cell membrane depending on the equilibrium potential for Cl(-) ions. Our results indicate that altered Cl(-) conductance is an important mechanism mediating membrane depolarization and contraction of aortic smooth muscle cells during stimulation with prostaglandin F(2 alpha). Given the significant role that prostaglandin F(2 alpha) and its biologically active isomers, the F(2) isoprostanes, play in the control of vascular tone during hypoxic and oxidative stress in the systemic circulation, alterations in Cl(-) channel function and expression may represent an important mechanism in the pathogenesis of abnormal blood flow regulation in disease states.

Epithelial cell-derived neutrophil-activating peptide-78 is present in fetal membranes and amniotic fluid at increased concentrations with intra-amniotic infection and preterm delivery

Intra-amniotic secretion and abundance of epithelial cell-derived neutrophil-activating peptide (ENA)-78, a potent chemoattractant and activator of neutrophils, was studied in the context of term and preterm parturition. Staining of ENA-78 immunoperoxidase was localized predominantly to chorionic trophoblasts and amniotic epithelium in term and preterm gestational membranes, with weaker and less consistent staining in decidual cells. The abundance of ENA-78 in membrane tissue homogenates was significantly increased ( approximately 4-fold) with term labor in amnion (n = 15), and with preterm labor ( approximately 30-fold) in amnion and choriodecidua (n = 31). In amnion tissue homogenate extracts, ENA-78 levels were positively correlated with the degree of leukocyte infiltration (r2 = 0.481). In amniotic fluids, median ENA-78 levels from pregnancies with preterm labor without intra-amniotic infection were significantly lower (P < 0.01 by ANOVA) than those from pregnancies with preterm deliveries with infection; levels in samples derived from term pregnancies were similar before and after labor. Production of ENA-78 by amnion monolayers was stimulated in a concentration-dependent fashion by both interleukin-1beta and tumor necrosis factor alpha. Production of ENA-78 by choriodecidual explants was increased modestly after 2-4 h of exposure to lipopolysaccharide (5 microg/ml). An immunoreactive doublet ( approximately 8 kDa) was detected in choriodecidual explant-conditioned media by immunoblotting. We conclude that ENA-78, derived from the gestational membranes, is present in increased abundance in the amniotic cavity in response to intrauterine infection and, hence, may play a role in the mechanism of infection-driven preterm birth and rupture of membranes secondary to leukocyte recruitment and activation.

Characterization of LPS-induced lung inflammation in cftr-/- mice and the effect of docosahexaenoic acid

The mechanism by which Pseudomonas causes excessive inflammation in the cystic fibrosis lung is unclear. We have reported that arachidonic acid is increased and docosahexaenoic acid (DHA) decreased in lung, pancreas, and ileum from cftr-/- mice. Oral DHA corrected this defect and reversed the pathology. To determine which mediators regulate inflammation in lungs from cftr-/- mice and whether inhibition occurs with DHA, cftr-/- and wild-type (WT) mice were exposed to aerosolized Pseudomonas lipopolysaccharide (LPS). After 2 days of LPS, tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-2, and KC levels in bronchoalveolar lavage fluid were increased in cftr-/- compared with WT mice and not suppressed by pretreatment with oral DHA. Neutrophil levels were not different between cftr-/- and WT mice. After 3 days of aerosolized LPS, neutrophil concentration, TNF-alpha, and the eicosanoids 6-keto-PGF1alpha, PGF2alpha, PGE2, and thromboxane B2 were all increased in bronchoalveolar lavage fluid from cftr-/- mice compared with WT controls. Oral DHA had no significant effect on TNF-alpha levels in cftr-/- mice. In contrast, neutrophils and eicosanoids were decreased in cftr-/- but not in WT mice treated with DHA, indicating that the effects of DHA on these inflammatory parameters may be related to correction of the membrane lipid defect.

NADPH oxidase is involved in prostaglandin F2alpha-induced hypertrophy of vascular smooth muscle cells: induction of NOX1 by PGF2alpha

Prostaglandin (PG) F(2alpha), one of the primary prostanoids generated in vascular tissue, is known to cause hypertrophy in vascular smooth muscle cells. To clarify the molecular mechanisms underlying PGF(2alpha)-induced hypertrophy, the involvement of reactive oxygen species was examined in a rat vascular smooth muscle cell line, A7r5. PGF(2alpha) and (+)-fluprostenol, a selective agonist of the PGF receptor, significantly increased intracellular O(2)(-) in A7r5. The PGF(2alpha)-induced O(2)(-) increase was suppressed by diphenyleneiodonium (DPI), an inhibitor of NADPH oxidase that has been reported to be the major source of O(2)(-) in vascular cells. The augmented synthesis of the protein induced by PGF(2alpha) or (+)-fluprostenol was suppressed in the presence of DPI. In PGF(2alpha) or (+)-fluprostenol-treated cells, a dose-dependent increase in the expression of NOX1, a homolog of the catalytic subunit of the phagocyte NADPH oxidase gp91(phox), was demonstrated by Northern blot analysis. Finally, depletion of NOX1 mRNA in the cells transfected with ribozymes targeted for three independent cleavage sites on the mRNA sequence significantly reduced the PGF(2alpha)-induced increase in protein synthesis. Taken together, these results suggest that hypertrophy of vascular smooth muscle cells caused by PGF(2alpha) is mediated by NOX1 induction and the resultant overproduction of O(2)(-) by NADPH oxidase.

Identification of the phospholipase A(2) isoforms that contribute to arachidonic acid release in hypoxic endothelial cells: limits of phospholipase A(2) inhibitors

Changes in endothelium functions during ischemia are thought to be of importance in numerous pathological conditions, with, for instance, an increase in the release of inflammatory mediators like prostaglandins. Here, we showed that hypoxia increases phospholipase A(2) (PLA(2)) activity in human umbilical vein endothelial cells. Both basal PLA(2) activity and PG synthesis are sensitive to BEL and AACOCF3, respectively, inhibitors of calcium-independent PLA(2) (iPLA(2)) and cytosolic PLA(2) (cPLA(2)), while OPC, an inhibitor of soluble PLA(2) (sPLA(2)) only inhibited the hypoxia-induced AA release and PGF(2alpha) synthesis. Hypoxia does not alter expression of iPLA(2), sPLA(2) and cPLA(2) and cycloheximide did not inhibit PLA(2) activation, indicating that hypoxia-induced increase in PLA(2) activity is due to activation rather than induction. However, mRNA levels for sPLA(2) displayed a 2-fold increase after 2 hr incubation under hypoxia. BAPTA, an intracellular calcium chelator, partially inhibited the AA release in normoxia and in hypoxia. Direct assays of specific PLA(2) activity showed an increase in sPLA(2) activity but not in cPLA(2) activity after 2hr hypoxia. Taken together, these results indicate that the hypoxia-induced increase in PLA(2) activity is mostly due to the activation of sPLA(2).