Prostaglandin E2 promotes degranulation-independent release of MCP-1 from mast cells

Ultrasonic-assisted extraction of a low molecular weight polysaccharide from Nostoc commune Vaucher and its structural characterization and immunomodulatory activity

In the current study, a novel crude polysaccharide (cNCEP) was extracted from N. commune Vaucher utilizing ultrasonic-assisted extraction (UAE) with 60 % ethanol, employing response surface methodology. The optimal yield of cNCEP was determined to be 8.07 ± 0.08 mg/g, achieved through ultrasonic-assisted extraction under the conditions of a material-to-liquid ratio of 1:22, temperature of 56 °C, power of 570 W, and duration of 147 min. Subsequent purification of NCEP via Sephadex G75 resulted in a novel polysaccharide with a molecular weight of 20.466 kDa. NCEP exhibited significant scavenging activites against DPPH and hydroxyl radicals, as well as notable in vitro immunomodulatory properties. Furthermore, the mechanisms underlying the immunomodulatory effects of NCEP, involving enhancement of immunity, were investigated, revealing potential regulation of MAPK and TLR4-IRF7-NF-κB signaling pathways through RNA-Seq and Western blot analyses. These findings highlight the promising potential of NCEP as an organic immunomodulatory agent and functional food ingredient.

Prostaglandin E2 in the Tumor Microenvironment, a Convoluted Affair Mediated by EP Receptors 2 and 4

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. SIGNIFICANCE STATEMENT: Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

Anti-inflammatory potential of simvastatin and amfenac in ARPE-19 cells; insights in preventing re-detachment and proliferative vitreoretinopathy after rhegmatogenous retinal detachment surgery

PURPOSE

Rhegmatogenous retinal detachment is a severe vision-threatening complication that can result into proliferative vitreoretinopathy (PVR) and re-detachment of the retina if recovery from surgery fails. Inflammation and changes in retinal pigment epithelial (RPE) cells are important contributors to the disease. Here, we studied the effects of simvastatin and amfenac on ARPE-19 cells under inflammatory conditions.

METHODS

ARPE-19 cells were pre-treated with simvastatin and/or amfenac for 24 h after which interleukin (IL)-1α or IL-1β was added for another 24 h. After treatments, lactate dehydrogenase release, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) processing, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activity, prostaglandin E2 (PGE2) level, and extracellular levels of IL-6, IL-8, monocytic chemoattractant protein (MCP-1), vascular endothelial growth factor (VEGF), and pigment epithelium-derived factor, as well as the production of reactive oxygen species (ROS) were determined.

RESULTS

Pre-treatment of human ARPE-19 cells with simvastatin reduced the production of IL-6, IL-8, and MCP-1 cytokines, PGE2 levels, as well as NF-κB activity upon inflammation, whereas amfenac reduced IL-8 and MCP-1 release but increased ROS production. Together, simvastatin and amfenac reduced the release of IL-6, IL-8, and MCP-1 cytokines as well as NF-κB activity but increased the VEGF release upon inflammation in ARPE-19 cells.

CONCLUSION

Our present study supports the anti-inflammatory capacity of simvastatin as pre-treatment against inflammation in human RPE cells, and the addition of amfenac complements the effect. The early modulation of local conditions in the retina can prevent inflammation induced PVR formation and subsequent retinal re-detachment.

Hyphal-associated protein expression is crucial for Candida albicans-induced eicosanoid biosynthesis in immune cells

Candida albicans causes opportunistic infections ranging from mucosal mycoses to life-threatening systemic infections in immunocompromised patients. During C. albicans infection, leukotrienes and prostaglandins are formed from arachidonic acid by 5-lipoxygenase (5-LOX) and cyclooxygenases, respectively to amplify inflammatory conditions, but also to initiate macrophage infiltration to achieve tissue homeostasis. Since less is known about the cellular mechanisms triggering such lipid mediator biosynthesis, we investigated the eicosanoid formation in monocyte-derived M1 and M2 macrophages, neutrophils and HEK293 cells transfected with 5-LOX and 5-LOX-activating protein (FLAP) in response to C. albicans yeast or hyphae. Leukotriene biosynthesis was exclusively induced by hyphae in neutrophils and macrophages, whereas prostaglandin E2 was also formed in response to yeast cells by M1 macrophages. Eicosanoid biosynthesis was significantly higher in M1 compared to M2 macrophages. In HEK_5-LOX/FLAP cells only hyphae activated the essential 5-LOX translocation to the nuclear membrane. Using yeast-locked C. albicans mutants, we demonstrated that hyphal-associated protein expression is critical in eicosanoid formation. For neutrophils and HEK_5-LOX/FLAP cells, hyphal wall protein 1 was identified as the essential surface protein that stimulates leukotriene biosynthesis. In summary, our data suggest that hyphal-associated proteins of C. albicans are central triggers of eicosanoid biosynthesis in human phagocytes.

Proteomic and Lipidomic Profiling of Calves Experimentally Co-Infected with Influenza D Virus and Mycoplasma bovis: Insights into the Host-Pathogen Interactions

The role of Influenza D virus (IDV) in bovine respiratory disease remains unclear. An in vivo experiment resulted in increased clinical signs, lesions, and pathogen replication in calves co-infected with IDV and Mycoplasma bovis (M. bovis), compared to single-infected calves. The present study aimed to elucidate the host-pathogen interactions and profile the kinetics of lipid mediators in the airways of these calves. Bronchoalveolar lavage (BAL) samples collected at 2 days post-infection (dpi) were used for proteomic analyses by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, lipidomic analyses were performed by LC-MS/MS on BAL samples collected at 2, 7 and 14 dpi. Whereas M. bovis induced the expression of proteins involved in fibrin formation, IDV co-infection counteracted this coagulation mechanism and downregulated other acute-phase response proteins, such as complement component 4 (C4) and plasminogen (PLG). The reduced inflammatory response against M. bovis likely resulted in increased M. bovis replication and delayed M. bovis clearance, which led to a significantly increased abundance of oxylipids in co-infected calves. The identified induced oxylipids mainly derived from arachidonic acid; were likely oxidized by COX-1, COX-2, and LOX-5; and peaked at 7 dpi. This paper presents the first characterization of BAL proteome and lipid mediator kinetics in response to IDV and M. bovis infection in cattle and raises hypotheses regarding how IDV acts as a co-pathogen in bovine respiratory disease.

Dual Blockade of EP2 and EP4 Signaling is Required for Optimal Immune Activation and Antitumor Activity Against Prostaglandin-Expressing Tumors

While the role of prostaglandin E2 (PGE2) in promoting malignant progression is well established, how to optimally block the activity of PGE2 signaling remains to be demonstrated. Clinical trials with prostaglandin pathway targeted agents have shown activity but without sufficient significance or dose-limiting toxicities that have prevented approval. PGE2 signals through four receptors (EP1-4) to modulate tumor progression. EP2 and EP4 signaling exacerbates tumor pathology and is immunosuppressive through potentiating cAMP production. EP1 and EP3 signaling has the opposite effect through increasing IP3 and decreasing cAMP. Using available small-molecule antagonists of single EP receptors, the cyclooxygenase-2 (COX-2) inhibitor celecoxib, or a novel dual EP2/EP4 antagonist generated in this investigation, we tested which approach to block PGE2 signaling optimally restored immunologic activity in mouse and human immune cells and antitumor activity in syngeneic, spontaneous, and xenograft tumor models. We found that dual antagonism of EP2 and EP4 together significantly enhanced the activation of PGE2-suppressed mouse and human monocytes and CD8+ T cells in vitro as compared with single EP antagonists. CD8+ T-cell activation was dampened by single EP1 and EP3 antagonists. Dual EP2/EP4 PGE2 receptor antagonists increased tumor microenvironment lymphocyte infiltration and significantly reduced disease burden in multiple tumor models, including in the adenomatous polyposis coli (APC)min+/- spontaneous colorectal tumor model, compared with celecoxib. These results support a hypothesis that redundancy of EP2 and EP4 receptor signaling necessitates a therapeutic strategy of dual blockade of EP2 and EP4. Here we describe TPST-1495, a first-in-class orally available small-molecule dual EP2/EP4 antagonist.

Significance

Prostaglandin (PGE2) drives tumor progression but the pathway has not been effectively drugged. We demonstrate significantly enhanced immunologic potency and antitumor activity through blockade of EP2 and EP4 PGE2 receptor signaling together with a single molecule.

Extracellular vesicles from human plasma dampen inflammation and promote tissue repair functions in macrophages

Although inflammation is a vital defence response to infection, if left uncontrolled, it can lead to pathology. Macrophages are critical players both in driving the inflammatory response and in the subsequent events required for restoring tissue homeostasis. Extracellular vesicles (EVs) are membrane-enclosed structures released by cells that mediate intercellular communication and are present in all biological fluids, including blood. Herein, we show that extracellular vesicles from plasma (pEVs) play a relevant role in the control of inflammation by counteracting PAMP-induced macrophage activation. Indeed, pEV-treatment of macrophages simultaneously with or prior to PAMP exposure reduced the secretion of pro-inflammatory IL-6 and TNF-α and increased IL-10 response. This anti-inflammatory activity was associated with the promotion of tissue-repair functions in macrophages, characterized by augmented efferocytosis and pro-angiogenic capacity, and increased expression of VEGFa, CD300e, RGS2 and CD93, genes involved in cell growth and tissue remodelling. We also show that simultaneous stimulation of macrophages with a PAMP and pEVs promoted COX2 expression and CREB phosphorylation as well as the accumulation of higher concentrations of PGE2 in cell culture supernatants. Remarkably, the anti-inflammatory activity of pEVs was abolished if cells were treated with a pharmacological inhibitor of COX2, indicating that pEV-mediated induction of COX2 is critical for the pEV-mediated inhibition of inflammation. Finally, we show that pEVs added to monocytes prior to their M-CSF-induced differentiation to macrophages increased efferocytosis and diminished pro-inflammatory cytokine responses to PAMP stimulation. In conclusion, our results suggest that pEVs are endogenous homeostatic modulators of macrophages, activating the PGE2/CREB pathway, decreasing the production of inflammatory cytokines and promoting tissue repair functions.

Advances in Understanding the Genetic Mechanisms of Zebrafish Renal Multiciliated Cell Development

Cilia are microtubule-based organelles that project from the cell surface. In humans and other vertebrates, possession of a single cilium structure enables an assortment of cellular processes ranging from mechanosensation to fluid propulsion and locomotion. Interestingly, cells can possess a single cilium or many more, where so-called multiciliated cells (MCCs) possess apical membrane complexes with several dozen or even hundreds of motile cilia that beat in a coordinated fashion. Development of MCCs is, therefore, integral to control fluid flow and/or cellular movement in various physiological processes. As such, MCC dysfunction is associated with numerous pathological states. Understanding MCC ontogeny can be used to address congenital birth defects as well as acquired disease conditions. Today, researchers used both in vitro and in vivo experimental models to address our knowledge gaps about MCC specification and differentiation. In this review, we summarize recent discoveries from our lab and others that have illuminated new insights regarding the genetic pathways that direct MCC ontogeny in the embryonic kidney using the power of the zebrafish animal model.

Rational design of biodegradable sulphonamide candidates treating septicaemia by synergistic dual inhibition of COX-2/PGE2 axis and DHPS enzyme

A new series of co-drugs was designed based on hybridising the dihydropteroate synthase (DHPS) inhibitor sulphonamide scaffold with the COX-2 inhibitor salicylamide pharmacophore through biodegradable linkage to achieve compounds with synergistic dual inhibition of COX-2/PGE2 axis and DHPS enzyme to enhance antibacterial activity for treatment of septicaemia. Compounds 5 b, 5j, 5n and 5o demonstrated potent in vitro COX-2 inhibitory activity comparable to celecoxib. 5j and 5o exhibited ED₅₀ lower than celecoxib in carrageenan-induced paw edoema test with % PGE2 inhibition higher than celecoxib. Furthermore, 5 b, 5j and 5n showed gastric safety profile like celecoxib. Moreover, in vivo antibacterial screening revealed that, 5j showed activity against S.aureus and E.coli higher than sulfasalazine. While, 5o revealed activity against E.coli higher than sulfasalazine and against S.aureus comparable to sulfasalazine. Compound 5j achieved the target goal as potent inhibitor of COX-2/PGE2 axis and in vivo broad-spectrum antibacterial activity against induced septicaemia in mice.

Reprogrammed Lipid Metabolism and the Lipid-Associated Hallmarks of Colorectal Cancer

Simple Summary

Colorectal cancer (CRC) is the third-most diagnosed cancer and the second-leading cause of cancer-related deaths worldwide. Limitations in early and accurate diagnosis of CRC gives rise to poor patient survival. Advancements in analytical techniques have improved our understanding of the cellular and metabolic changes occurring in CRC and potentiate avenues for improved diagnostic and therapeutic strategies. Lipids are metabolites with important biological functions; however, their role in CRC is poorly understood. Here, we provide an in-depth review of the recent literature concerning lipid alterations in CRC and propose eight lipid metabolism-associated hallmarks of CRC.

Abstract

Lipids have diverse structures, with multifarious regulatory functions in membrane homeostasis and bioenergetic metabolism, in mediating functional protein–lipid and protein–protein interactions, as in cell signalling and proliferation. An increasing body of evidence supports the notion that aberrant lipid metabolism involving remodelling of cellular membrane structure and changes in energy homeostasis and signalling within cancer-associated pathways play a pivotal role in the onset, progression, and maintenance of colorectal cancer (CRC) and their tumorigenic properties. Recent advances in analytical lipidome analysis technologies have enabled the comprehensive identification and structural characterization of lipids and, consequently, our understanding of the role they play in tumour progression. However, despite progress in our understanding of cancer cell metabolism and lipidomics, the key lipid-associated changes in CRC have yet not been explicitly associated with the well-established ‘hallmarks of cancer’ defined by Hanahan and Weinberg. In this review, we summarize recent findings that highlight the role of reprogrammed lipid metabolism in CRC and use this growing body of evidence to propose eight lipid metabolism-associated hallmarks of colorectal cancer, and to emphasize their importance and linkages to the established cancer hallmarks.

Bioactive lipid screening during respiratory tract infections with bacterial and viral pathogens in mice

INTRODUCTION

Respiratory tract infections are a worldwide health problem for humans and animals. Different cell types produce lipid mediators in response to infections, which consist of eicosanoids like hydroxyeicosatetraenoic acids (HETEs) or oxylipins like hydroxydocosahexaenoic acids (HDHAs). Both substance classes possess immunomodulatory functions. However, little is known about their role in respiratory infections.

OBJECTIVES

Here, we aimed to analyze the lipid mediator imprint of different organs of C57BL/6J mice after intranasal mono-infections with Streptococcus pneumoniae (pneumococcus), Staphylococcus aureus or Influenza A virus (IAV) as wells as pneumococcal-IAV co-infection.

METHODS

C57BL/6J mice were infected with different pathogens and lungs, spleen, and plasma were collected. Lipid mediators were analyzed using HPLC-MS/MS. In addition, spatial-distribution of sphingosine 1-phosphate (S1P) and ceramide 1-phosphates (C1P) in tissue samples was examined using MALDI-MS-Imaging. The presence of bacterial pathogens in the lung was confirmed via immunofluorescence staining.

RESULTS

We found IAV specific changes for different HDHAs and HETEs in mouse lungs as well as enhanced levels of 20-HETE in severe S. aureus infection. Moreover, MALDI-MS-Imaging analysis showed an accumulation of C1P and a decrease of S1P during co-infection in lung and spleen. Long chain C1P was enriched in the red and not in the white pulp of the spleen.

CONCLUSIONS

Lipid mediator analysis showed that host synthesis of bioactive lipids is in part specific for a certain pathogen, in particular for IAV infection. Furthermore, MS-Imaging displayed great potential to study infections and revealed changes of S1P and C1P in lungs and spleen of co-infected animals, which was not described before.

Polyunsaturated fatty acids and fatty acid-derived lipid mediators: Recent advances in the understanding of their biosynthesis, structures, and functions

Polyunsaturated fatty acids (PUFAs) are structural components of membrane phospholipids, and influence cellular function via effects on membrane properties, and also by acting as a precursor pool for lipid mediators. These lipid mediators are formed via activation of pathways involving at least one step of dioxygen-dependent oxidation, and are consequently called oxylipins. Their biosynthesis can be either enzymatically-dependent, utilising the promiscuous cyclooxygenase, lipoxygenase, or cytochrome P450 mixed function oxidase pathways, or nonenzymatic via free radical-catalyzed pathways. The oxylipins include the classical eicosanoids, comprising prostaglandins, thromboxanes, and leukotrienes, and also more recently identified lipid mediators. With the advent of new technologies there is growing interest in identifying these different lipid mediators and characterising their roles in health and disease. This review brings together contributions from some of those at the forefront of research into lipid mediators, who provide brief introductions and summaries of current understanding of the structure and functions of the main classes of nonclassical oxylipins. The topics covered include omega-3 and omega-6 PUFA biosynthesis pathways, focusing on the roles of the different fatty acid desaturase enzymes, oxidized linoleic acid metabolites, omega-3 PUFA-derived specialized pro-resolving mediators, elovanoids, nonenzymatically oxidized PUFAs, and fatty acid esters of hydroxy fatty acids.

Mast Cells Trigger Disturbed Bone Healing in Osteoporotic Mice

Mast cells are important tissue-resident sensor and effector immune cells but also play a major role in osteoporosis development. Mast cells are increased in numbers in the bone marrow of postmenopausal osteoporotic patients, and mast cell-deficient mice are protected from ovariectomy (OVX)-induced bone loss. In this study, we showed that mast cell-deficient Mcpt5-Cre R-DTA mice were protected from OVX-induced disturbed fracture healing, indicating a critical role for mast cells in the pathomechanisms of impaired bone repair under estrogen-deficient conditions. We revealed that mast cells trigger the fracture-induced inflammatory response by releasing inflammatory mediators, including interleukin-6, midkine (Mdk), and C-X-C motif chemokine ligand 10 (CXCL10), and promote neutrophil infiltration into the fracture site in OVX mice. Furthermore, mast cells were responsible for reduced osteoblast and increased osteoclast activities in OVX mice callus, as well as increased receptor activator of NF-κB ligand serum levels in OVX mice. Additional in vitro studies with human cells showed that mast cells stimulate osteoclastogenesis by releasing the osteoclastogenic mediators Mdk and CXCL10 in an estrogen-dependent manner, which was mediated via the estrogen receptor alpha on mast cells. In conclusion, mast cells negatively affect the healing of bone fractures under estrogen-deficient conditions. Hence, targeting mast cells might provide a therapeutic strategy to improve disturbed bone repair in postmenopausal osteoporosis. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Tumor-Associated Mast Cells in Urothelial Bladder Cancer: Optimizing Immuno-Oncology

Urothelial bladder cancer (UBC) is one of the most prevalent and aggressive malignancies. Recent evidence indicates that the tumor microenvironment (TME), including a variety of immune cells, is a critical modulator of tumor initiation, progression, evolution, and treatment resistance. Mast cells (MCs) in UBC are possibly involved in tumor angiogenesis, tissue remodeling, and immunomodulation. Moreover, tumor-infiltration by MCs has been reported in early-stage UBC patients. This infiltration is linked with a favorable or unfavorable prognosis depending on the tumor type and location. Despite the discrepancy of MC function in tumor progression, MCs can modify the TME to regulate the immunity and infiltration of tumors by producing an array of mediators. Nonetheless, the precise role of MCs in UBC tumor progression and evolution remains unknown. Thus, this review discusses some critical roles of MCs in UBC. Patients with UBC are treated at both early and late stages by immunotherapeutic methods, including intravenous bacillus Calmette–Guérin instillation and immune checkpoint blockade. An understanding of the patient response and resistance mechanisms in UBC is required to unlock the complete potential of immunotherapy. Since MCs are pivotal to understand the underlying processes and predictors of therapeutic responses in UBC, our review also focuses on possible immunotherapeutic treatments that involve MCs.

C-C motif chemokine receptor 2 as a novel intermediate in the ovulatory cascade

Expression of immune function genes within follicle cells has been reported in ovaries from many species. Recent work from our laboratory showed a direct effect of the monocyte chemoattractant protein 1/C-C motif chemokine receptor 2 system within the feline cumulus oocyte complex, by increasing the mRNA levels of key genes involved in the ovulatory cascade in vitro. Studies were designed to evaluate if C-C motif chemokine receptor 2 acts as a novel mediator of the ovulatory cascade in vitro. Therefore, feline cumulus oocyte complexes were cultured in the presence or absence of a highly selective C-C motif chemokine receptor 2 antagonist together with known inducers of cumulus-oocyte expansion and/or oocyte maturation to assess mRNA expression of key genes related to periovulatory events in other species as well as oocyte maturation. Also, the effects of recombinant monocyte chemoattractant protein 1 on spontaneous or gonadotrophin-induced oocyte maturation were assessed. This is an in vitro system using isolated cumulus oocyte complexes from feline ovaries. The present study reveals the modulation of several key ovulatory genes by a highly selective C-C motif chemokine receptor 2 antagonist. However, this antagonist was not enough to block the oocyte maturation induced by gonadotropins or amphiregulin. Nonetheless, recombinant monocyte chemoattractant protein 1 had a significant effect on spontaneous oocyte maturation, increasing the percentage of metaphase II stage oocytes in comparison to the control. This is the first study in any species to establish C-C motif chemokine receptor 2 as a mediator of some actions of the mid-cycle gonadotrophin surge.

miR-708-5p enhances erlotinib/paclitaxel efficacy and overcomes chemoresistance in lung cancer cells

Lung cancer is a collection of aggressive tumors generally not diagnosed until late-stage, resulting in high mortality rates. The vast majority of non-small cell lung cancer (NSCLC) patients undergo combinatory chemotherapeutic treatment, which initially reduces tumor growth, but frequently becomes ineffective due to toxicity and resistance. Researchers have identified multiple signaling pathways involved in lung cancer chemoresistance, including cyclooxygenase-2 (COX-2)/microsomal prostaglandin E synthase-1 (mPGES-1) derived prostaglandin E2 (PGE₂). While COX-2 inhibitors have shown promise in the clinic, their use is limited due to severe side effects. One novel approach to effectively suppress COX-2 signaling is through microRNA (miRNA). MiRNAs are small-noncoding RNAs commonly misexpressed in cancer. One tumor suppressive miRNA, miR-708-5p, has been shown to repress pro-resistant signaling pathways, including COX-2 and mPGES-1. Here, we demonstrate that chemotherapies reduce COX-2 expression, possibly through induction of miR-708-5p. Moreover, combination treatment of erlotinib (ERL) or paclitaxel (PAC) with miR-708-5p enhances COX-2 and mPGES-1 protein suppression. We also show that combination chemotherapeutic and miR-708-5p treatment intensifies the anti-proliferative and pro-apoptotic effects of ERL and PAC. We also created ERL and PAC resistant lung cancer cell lines, which have increased COX-2 expression and diminished miR-708-5p levels compared to naïve lung cancer cells. While ERL and PAC treatments do not alter resistant cell phenotype alone, combination treatment with miR-708-5p partially restores the chemotherapies' anti-proliferative effects and fully restores their pro-apoptotic qualities. These data suggest miR-708-5p may have potential combinatory therapeutic value to more efficaciously treat lung tumors while overcoming chemoresistance.

miR-708-5p targets oncogenic prostaglandin E2 production to suppress a pro-tumorigenic phenotype in lung cancer cells

Many cancers maintain an inflammatory microenvironment to promote their growth. Lung cancer is of particular importance, as it is the deadliest cancer worldwide. One inflammatory pathway commonly dysregulated in cancer is the metabolism of arachidonic acid (AA) by Cyclooxygenase-2 (COX-2) and microsomal Prostaglandin E Synthase 1 (mPGES-1) into Prostaglandin E2 (PGE2). While researchers have identified PGE2's pro-tumorigenic functions, the mechanisms governing overexpression of COX-2 and mPGES-1 are incompletely understood. MicroRNAs (miRNAs) are important post-transcriptional regulators commonly dysregulated in cancer. Interestingly, miR-708-5p (miR-708) is predicted to target both COX-2 and mPGES-1. In this study, we show that high miR-708 expression is associated with survival rates in lung squamous cell carcinoma patients. miR-708 also represses PGE2 production by suppressing both COX-2 and mPGES-1 expression in lung cancer cells. miR-708 regulation of COX-2 and mPGES-1 is mediated through targeting of their 3' untranslated regions (UTRs). Moreover, miR-708 decreases proliferation, survival, and migration of lung cancer cells, which can be partially attributed to miR-708's inhibition of PGE2 signaling. Lastly, we identify novel miR-708 predicted targets and possible regulators of miR-708 expression in lung cancer. Collectively, these data demonstrate that dysregulated miR-708 expression contributes to exacerbated PGE2 production, leading to an enhanced pro-tumorigenic phenotype in lung cancer cells.

Prostaglandin-E2 deficiency during late pregnancy and the associated increase in interleukin-1β derived from periaortic lymph nodes lead to abortion

Prostaglandin E2 (PGE2) is a hormone with many physiological functions. During pregnancy, it is generally believed that there is a high level of PGE2 at the final stage of pregnancy, which induces the contraction of uterine smooth muscle and promotes the occurrence of childbirth. However, we find that high PGE2 levels are present throughout late pregnancy in mice, not just during childbirth, and that PGE2 deficiency induced by indomethacin during late pregnancy causes damage to the placental labyrinth and eventually leads to abortion. Interestingly, the damage is closely related to inflammation, which involves the role of inflammatory factors produced by the periaortic lymph nodes (PLNs) near the uterus. Further, through RNA sequencing, we reveal that PLNs produce a large amount of interleukin-1β (IL-1β) when exposed to PGE2 deficiency, which causes damage to the placental labyrinth, probably via destroying the extracellular matrix. Finally, events leading to abortion following indomethacin administration are effectively prevented by supplementing PGE2 or by PLN removal. These results suggest that high levels of PGE2 during late pregnancy protect fetuses from inflammatory damage related to IL-1β. This work suggests a new role of PGE2 during late pregnancy and may provide potential therapeutic strategies for pathological pregnancy.

Emerging Roles of Mast Cells in the Regulation of Lymphatic Immuno-Physiology

Mast cells (MCs) are abundant in almost all vascularized tissues. Furthermore, their anatomical proximity to lymphatic vessels and their ability to synthesize, store and release a large array of inflammatory and vasoactive mediators emphasize their significance in the regulation of the lymphatic vascular functions. As a major secretory cell of the innate immune system, MCs maintain their steady-state granule release under normal physiological conditions; however, the inflammatory response potentiates their ability to synthesize and secrete these mediators. Activation of MCs in response to inflammatory signals can trigger adaptive immune responses by dendritic cell-directed T cell activation. In addition, through the secretion of various mediators, cytokines and growth factors, MCs not only facilitate interaction and migration of immune cells, but also influence lymphatic permeability, contractility, and vascular remodeling as well as immune cell trafficking through the lymphatic vessels. In summary, the consequences of these events directly affect the lymphatic niche, influencing inflammation at multiple levels. In this review, we have summarized the recent advancements in our understanding of the MC biology in the context of the lymphatic vascular system. We have further highlighted the MC-lymphatic interaction axis from the standpoint of the tumor microenvironment.

CCL22 Signaling in the Tumor Environment

T cell-mediated elimination of malignant cells is one cornerstone of endogenous and therapeutically induced antitumor immunity. Tumors exploit numerous regulatory mechanisms to suppress T cell immunity. Regulatory T cells (T regs) play a crucial role in this process due to their ability to inhibit antitumoral immune responses and they are known to accumulate in various cancer entities. The chemokine CCL22, predominately produced by dendritic cells (DCs), regulates T reg migration via binding to its receptor CCR4. CCL22 controls T cell immunity, both by recruiting T regs to the tumor tissue and by promoting the formation of DC-T reg contacts in the lymph node. Here, we review the current knowledge on the role of CCL22 in cancer immunity. After revising the principal mechanisms of CCL22-induced immune suppression, we address the factors leading to CCL22 expression and ways of targeting this chemokine therapeutically. Therapeutic interventions to the CCL22-CCR4 axis may represent a promising strategy in cancer immunotherapy.

Prostaglandin E2 as a potent therapeutic target for treatment of colon cancer

Although colon cancer is one of the most important triggers of cancer related mortality, a few therapeutic options exist for this disease, including combination chemotherapy, anti-EGFR and anti-angiogenic agents. However, none of these therapeutics are fully effective for complete remission, and this issue needs further investigations, particularly in the patients with advanced disease. It has been shown that colon carcinogenesis process is associated with upregulation of prostaglandin (PG) levels. Moreover, conversion of pre-malignant cells to malignant was also related with increased generation of PGs in susceptible subjects. Among the prostanoids, PGE2 is the most important produced member which generated in high levels by colon tumor cells. Generation of PGE2 by action of cyclooxygenase (COX)-2 can promote growth and development, resistance to apoptosis, proliferation, invasion and metastasis, angiogenesis and drug resistance in colon cancer. Increased levels of PGE2 and COX-2 in colon cancer is reported by various investigators which was associated with disease progression. It is suggested that there is a positive feedback loop between COX-2 and PGE2, in which function of COX-2 induces generation of PGE2, and upregulation of PGE2 increases the expression of COX-2 in colon cancer. Although an existence of this feedback loop is well-documented, its precise mechanism, signaling pathways, and the particular E-type prostanoid (EP) receptor mediating this feedback are elusive. Therefore, it seems that targeting COX-2/PGE2/EP receptors may be supposed as a potent therapeutic strategy for treatment of colon cancer. In this review, we try to clarify the role of PGE2 in cancer progression and its targeting for treatment of colon cancer.

Mast cells: A double-edged sword in cancer

Mast cells (MCs), a type of innate immune cells, are derived from myeloid stem cells, sometimes known as mastocytes or labrocytes, and contain many granules rich in histamine and heparin. The mentioned cells are able to release various mediators such as cytokines, leukotrienes, and a large number of proteases into the environment. Many studies and experiments have established the infiltration of MCs into the tumor site. However, the findings are highly controversial to determine whether these immune cells contribute to the growth and development of the tumor or cause anti-tumor immune responses. Various studies have revealed that MCs have a pro-tumorigenic or anti-tumorigenic role depending on the type of cancer, the degree of tumor progression, and the location of these immune cells in the tumor bulk. Although these types of immune cells cause angiogenesis and tumor progression in some cancers, they have a significant anti-tumor role in some other types of cancers. In general, although a number of studies have specified the protective role of MCs in cancers, the increased number of MCs in the blood and microenvironment of tumors, as well as the increased level of angiogenesis and tumor progression, has been indicated in another array of studies. The function of MCs against or in favor of the cancers still requires further investigations to more accurately and specifically determine the role of MCs in the cancers. The function of MCs in tumors and their various roles in case of exposure to the cancer cells have been addressed in the present review. The concluding section of the present study recommends a number of methods for modification of MCs in cancer immunotherapy.

Arachidonic Acid Derived Lipid Mediators Influence Kaposi's Sarcoma-Associated Herpesvirus Infection and Pathogenesis

Kaposi’s sarcoma-associated herpesvirus (KSHV) infection, particularly latent infection is often associated with inflammation. The arachidonic acid pathway, the home of several inflammation and resolution associated lipid mediators, is widely altered upon viral infections. Several in vitro studies show that these lipid mediators help in the progression of viral pathogenesis. This review summarizes the findings related to human herpesvirus KSHV infection and arachidonic acid pathway metabolites. KSHV infection has been shown to promote inflammation by upregulating cyclooxygenase-2 (COX-2), 5 lipoxygenase (5LO), and their respective metabolites prostaglandin E₂ (PGE₂) and leukotriene B4 (LTB₄) to promote latency and an inflammatory microenvironment. Interestingly, the anti-inflammatory lipid mediator lipoxin is downregulated during KSHV infection to facilitate infected cell survival. These studies aid in understanding the role of arachidonic acid pathway metabolites in the progression of viral infection, the host inflammatory response, and pathogenesis. With limited therapeutic options to treat KSHV infection, use of inhibitors to these inflammatory metabolites and their synthetic pathways or supplementing anti-inflammatory lipid mediators could be an effective alternative therapeutic.

Evaluation of four clinical laboratory parameters for the diagnosis of myalgic encephalomyelitis

Background

Myalgic encephalomyelitis (ME) is a complex and debilitating disease that often initially presents with flu-like symptoms, accompanied by incapacitating fatigue. Currently, there are no objective biomarkers or laboratory tests that can be used to unequivocally diagnosis ME; therefore, a diagnosis is made when a patient meets series of a costly and subjective inclusion and exclusion criteria. The purpose of the present study was to evaluate the utility of four clinical parameters in diagnosing ME.

Methods

In the present study, we utilized logistic regression and classification and regression tree analysis to conduct a retrospective investigation of four clinical laboratory in 140 ME cases and 140 healthy controls.

Results

Correlations between the covariates ranged between [− 0.26, 0.61]. The best model included the serum levels of the soluble form of CD14 (sCD14), serum levels of prostaglandin E2 (PGE₂), and serum levels of interleukin 8, with coefficients 0.002, 0.249, and 0.005, respectively, and p-values of 3 × 10⁻⁷, 1 × 10⁻⁵, and 3 × 10⁻³, respectively.

Conclusions

Our findings show that these parameters may help physicians in their diagnosis of ME and may additionally shed light on the pathophysiology of this disease.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1696-z) contains supplementary material, which is available to authorized users.

Mast Cell Activation and KSHV Infection in Kaposi Sarcoma

Purpose: Kaposi sarcoma (KS) is a vascular tumor initiated by infection of endothelial cells (ECs) with KS-associated herpesvirus (KSHV). KS is dependent on sustained proinflammatory signals provided by intralesional leukocytes and continued infection of new ECs. However, the sources of these cytokines and infectious virus within lesions are not fully understood. Here, mast cells (MCs) are identified as proinflammatory cells within KS lesions that are permissive for, and activated by, infection with KSHV.Experimental Design: Three validated MC lines were used to assess permissivity of MCs to infection with KSHV and to evaluate MCs activation following infection. Biopsies from 31 AIDS-KS cases and 11 AIDS controls were evaluated by IHC for the presence of MCs in KS lesions and assessment of MC activation state and infection with KSHV. Plasma samples from 26 AIDS-KS, 13 classic KS, and 13 healthy adults were evaluated for levels of MC granule contents tryptase and histamine.Results: In culture, MCs supported latent and lytic KSHV infection, and infection-induced MC degranulation. Within KS lesions, MCs were closely associated with spindle cells. Furthermore, MC activation was extensive within patients with KS, reflected by elevated circulating levels of tryptase and a histamine metabolite. One patient with clinical signs of extensive MC activation was treated with antagonists of MC proinflammatory mediators, which resulted in a rapid and durable regression of AIDS-KS lesions.Conclusions: Using complimentary in vitro and in vivo studies we identify MCs as a potential long-lived reservoir for KSHV and a source of proinflammatory mediators within the KS lesional microenvironment. In addition, we identify MC antagonists as a promising novel therapeutic approach for KS. Clin Cancer Res; 24(20); 5085-97. ©2018 AACR.

Ibuprofen supports macrophage differentiation, T cell recruitment, and tumor suppression in a model of postpartum breast cancer

BACKGROUND

Women diagnosed with breast cancer within 5 years postpartum (PPBC) have poorer prognosis than age matched nulliparous women, even after controlling for clinical variables known to impact disease outcomes. Through rodent modeling, the poor prognosis of PPBC has been attributed to physiologic mammary gland involution, which shapes a tumor promotional microenvironment through induction of wound-healing-like programs including myeloid cell recruitment. Previous studies utilizing immune compromised mice have shown that blocking prostaglandin synthesis reduces PPBC tumor progression in a tumor cell extrinsic manner. Given the reported roles of prostaglandins in myeloid and T cell biology, and the established importance of these immune cell populations in dictating tumor growth, we investigate the impact of involution on shaping the tumor immune milieu and its mitigation by ibuprofen in immune competent hosts.

METHODS

In a syngeneic (D2A1) orthotopic Balb/c mouse model of PPBC, we characterized the impact of mammary gland involution and ibuprofen treatment on the immune milieu in tumors and draining lymph nodes utilizing flow cytometry, multiplex IHC, lipid mass spectroscopy and cytokine arrays. To further investigate the impact of ibuprofen on programming myeloid cell populations, we performed RNA-Seq on in vivo derived mammary myeloid cells from ibuprofen treated and untreated involution group mice. Further, we examined direct effects of ibuprofen through in vitro bone marrow derived myeloid cell cultures.

RESULTS

Tumors implanted into the mammary involution microenvironment grow more rapidly and display a distinct immune milieu compared to tumors implanted into glands of nulliparous mice. This milieu is characterized by increased presence of immature monocytes and reduced numbers of T cells and is reversed upon ibuprofen treatment. Further, ibuprofen treatment enhances Th1 associated cytokines as well as promotes tumor border accumulation of T cells. Safety studies demonstrate ibuprofen does not impede gland involution, impact subsequent reproductive success, nor promote auto-reactivity as detected through auto-antibody and naïve T cell priming assays.

CONCLUSIONS

Ibuprofen administration during the tumor promotional microenvironment of the involuting mammary gland reduces overall tumor growth and enhances anti-tumor immune characteristics while avoiding adverse autoimmune reactions. In sum, these studies implicate beneficial prophylactic use of ibuprofen during the pro-tumorigenic window of mammary gland involution.

Prostaglandin EP2 receptor: Novel therapeutic target for human cancers (Review)

Prostaglandin E2 (PGE2) receptor 2 subtype (EP2), which is a metabolite of arachidonic acid that binds with and regulates cellular responses to PGE2, is associated with numerous physiological and pathological events in a wide range of tissues. As a stimulatory G protein‑coupled receptor, PGE2‑induced EP2 activation can activate adenylate cyclase, leading to increased cytoplasmic cAMP levels and activation of protein kinase A. The EP2 receptor can also activate the glycogen synthase kinase 3β and β‑catenin pathways. The present study aimed to review the roles of the EP2 receptor in tumor development, including immunity, chronic inflammation, angiogenesis, metastasis and multidrug resistance. Furthermore, the involvement of the EP2 receptor signaling pathway in cancer was discussed. Understanding the role and mechanisms of action of the EP2 receptor, and its importance in targeted therapy, may help identify novel methods to improve management of numerous types of cancer.

The prostaglandin E2 receptor EP3 controls CC-chemokine ligand 2-mediated neuropathic pain induced by mechanical nerve damage

Prostaglandin (PG) E₂ is an important lipid mediator that is involved in several pathophysiological processes contributing to fever, inflammation, and pain. Previous studies have shown that early and continuous application of nonsteroidal anti-inflammatory drugs significantly reduces pain behavior in the spared nerve injury (SNI) model for trauma-induced neuropathic pain. However, the role of PGE₂ and its receptors in the development and maintenance of neuropathic pain is incompletely understood but may help inform strategies for pain management. Here, we sought to define the nociceptive roles of the individual PGE₂ receptors (EP1-4) in the SNI model using EP knockout mice. We found that PGE₂ levels at the site of injury were increased and that the expression of the terminal synthase for PGE₂, cytosolic PGE synthase was up-regulated in resident positive macrophages located within the damaged nerve. Only genetic deletion of the EP3 receptor affected nociceptive behavior and reduced the development of late-stage mechanical allodynia as well as recruitment of immune cells to the injured nerve. Importantly, EP3 activation induced the release of CC-chemokine ligand 2 (CCL2), and antagonists against the CCL2 receptor reduced mechanical allodynia in WT but not in EP3 knockout mice. We conclude that selective inhibition of EP3 might present a potential approach for reducing chronic neuropathic pain.

The Neurobeachin-like 2 Protein Regulates Mast Cell Homeostasis

The neurobeachin-like 2 protein (Nbeal2) belongs to the family of beige and Chediak-Higashi (BEACH) domain proteins. Loss-of-function mutations in the human NBEAL2 gene or Nbeal2 deficiency in mice cause gray platelet syndrome, a bleeding disorder characterized by macrothrombocytopenia, splenomegaly, and paucity of α-granules in megakaryocytes and platelets. We found that in mast cells, Nbeal2 regulates the activation of the Shp1-STAT5 signaling axis and the composition of the c-Kit/STAT signalosome. Furthermore, Nbeal2 mediates granule formation and restricts the expression of the transcription factors, IRF8, GATA2, and MITF as well as of the cell-cycle inhibitor p27, which are essential for mast cell differentiation, proliferation, and cytokine production. These data demonstrate the relevance of Nbeal2 in mast cells above and beyond granule biosynthesis.

Growth and adherence of Staphylococcus aureus were enhanced through the PGE2 produced by the activated COX-2/PGE2 pathway of infected oral epithelial cells

Staphylococcus aureus is a major pathogen of varieties of oral mucous infection. Prostaglandin E2 (PGE₂) is a pro-inflammatory factor and Cyclooxygenase 2 (COX-2) is a critical enzyme of PGE₂ biosynthesis. The purpose of this study is to investigate whether Staphylococcus aureus can increase PGE₂ production of oral epithelial cells and how PGE₂ functions in the growth and adherence of Staphylococcus aureus. mRNA levels of COX-2, fnbpA and fnbpB were estimated by quantitative PCR. PGE₂ production was measured by Enzyme Linked Immunosorbent Assay (ELISA). The binding biomass of Staphylococcus aureus to human fibronectin was investigated by crystal violet staining and confocal laser scanning microscopy and the adherent force was measured by atomic force microscope (AFM). The COX-2 mRNA level and PGE₂ production were increased by Staphylococcus aureus. PGE₂ promoted the growth and biofilm formation of Staphylococcus aureus, enhanced the attachment of Staphylococcus aureus to the human fibronectin as well as to the HOK cells. The transcription of fnbpB was up-regulated by PGE₂ in both early and middle exponential phase but not fnbpA. These results suggest that the activation of COX-2/PGE₂ pathway in oral epithelial cell by Staphylococcus aureus can in turn facilitate the growth and the ability to adhere of the pathogen. These findings uncover a new function of PGE₂ and may lead to the potential of COX-2/PGE₂ targeting in the therapy of inflammation and cancer in both which the COX-2/PGE₂ pathway were observed activated.

Crosstalk Among UV-Induced Inflammatory Mediators, DNA Damage and Epigenetic Regulators Facilitates Suppression of the Immune System

The suppression of the immune system by overexposure to ultraviolet (UV) radiation has been implicated in the initiation and progression of photocarcinogenesis. Numerous changes occur in the skin on UVB exposure, including the generation of inflammatory mediators, DNA damage, epigenetic modifications, and migration and functional alterations in the antigen-presenting dendritic cells. Although each of these alterations can elicit a cascade of events that have the potential to modulate immune sensitivity alone, there is emerging evidence that there is considerable crosstalk between these cascades. The development of an understanding of UV-induced changes in the skin that culminate in UV-induced immunosuppression, which has been implicated in the risk of nonmelanoma skin cancer, as a network of events has implications for the development of more effective chemopreventive strategies. In the current review article, we discuss the evidence of interactions between the various molecular targets and signaling mechanisms associated with UV-induced immunosuppression.

Eicosanoid pathway in colorectal cancer: Recent updates

Enzymatic metabolism of the 20C polyunsaturated fatty acid (PUFA) arachidonic acid (AA) occurs via the cyclooxygenase (COX) and lipoxygenase (LOX) pathways, and leads to the production of various bioactive lipids termed eicosanoids. These eicosanoids have a variety of functions, including stimulation of homeostatic responses in the cardiovascular system, induction and resolution of inflammation, and modulation of immune responses against diseases associated with chronic inflammation, such as cancer. Because chronic inflammation is essential for the development of colorectal cancer (CRC), it is not surprising that many eicosanoids are implicated in CRC. Oftentimes, these autacoids work in an antagonistic and highly temporal manner in inflammation; therefore, inhibition of the pro-inflammatory COX-2 or 5-LOX enzymes may subsequently inhibit the formation of their essential products, or shunt substrates from one pathway to another, leading to undesirable side-effects. A better understanding of these different enzymes and their products is essential not only for understanding the importance of eicosanoids, but also for designing more effective drugs that solely target the inflammatory molecules found in both chronic inflammation and cancer. In this review, we have evaluated the cancer promoting and anti-cancer roles of different eicosanoids in CRC, and highlighted the most recent literature which describes how those molecules affect not only tumor tissue, but also the tumor microenvironment. Additionally, we have attempted to delineate the roles that eicosanoids with opposing functions play in neoplastic transformation in CRC through their effects on proliferation, apoptosis, motility, metastasis, and angiogenesis.

Plant Hormone Salicylic Acid Produced by a Malaria Parasite Controls Host Immunity and Cerebral Malaria Outcome

The apicomplexan parasite Toxoplasma gondii produces the plant hormone abscisic acid, but it is unclear if phytohormones are produced by the malaria parasite Plasmodium spp., the most important parasite of this phylum. Here, we report detection of salicylic acid, an immune-related phytohormone of land plants, in P. berghei ANKA and T. gondii cell lysates. However, addition of salicylic acid to P. falciparum and T. gondii culture had no effect. We transfected P. falciparum 3D7 with the nahG gene, which encodes a salicylic acid-degrading enzyme isolated from plant-infecting Pseudomonas sp., and established a salicylic acid-deficient mutant. The mutant had a significantly decreased concentration of parasite-synthesized prostaglandin E₂, which potentially modulates host immunity as an adaptive evolution of Plasmodium spp. To investigate the function of salicylic acid and prostaglandin E₂ on host immunity, we established P. berghei ANKA mutants expressing nahG. C57BL/6 mice infected with nahG transfectants developed enhanced cerebral malaria, as assessed by Evans blue leakage and brain histological observation. The nahG-transfectant also significantly increased the mortality rate of mice. Prostaglandin E₂ reduced the brain symptoms by induction of T helper-2 cytokines. As expected, T helper-1 cytokines including interferon-γ and interleukin-2 were significantly elevated by infection with the nahG transfectant. Thus, salicylic acid of Plasmodium spp. may be a new pathogenic factor of this threatening parasite and may modulate immune function via parasite-produced prostaglandin E₂.

The Pharmacological and Physiological Role of Multidrug-Resistant Protein 4

Multidrug-resistant protein 4 (MRP4), a member of the C subfamily of ATP-binding cassette transporters, is distributed in a variety of tissues and a number of cancers. As a drug transporter, MRP4 is responsible for the pharmacokinetics and pharmacodynamics of numerous drugs, especially antiviral drugs, antitumor drugs, and diuretics. In this regard, the functional role of MRP4 is affected by a number of factors, such as genetic mutations; tissue-specific transcriptional regulations; post-transcriptional regulations, including miRNAs and membrane internalization; and substrate competition. Unlike other C family members, MRP4 is in a pivotal position to transport cellular signaling molecules, through which it is tightly connected to the living activity and physiologic processes of cells and bodies. In the context of several cancers in which MRP4 is overexpressed, MRP4 inhibition shows striking effects against cancer progression and drug resistance. In this review, we describe the role of MRP4 more specifically in both healthy conditions and disease states, with an emphasis on its potential as a drug target.

Lipid mediators are critical in resolving inflammation: a review of the emerging roles of eicosanoids in diabetes mellitus

The biosynthesis pathway of eicosanoids derived from arachidonic acid, such as prostaglandins and leukotrienes, relates to the pathophysiology of diabetes mellitus (DM). A better understanding of how lipid mediators modulate the inflammatory process may help recognize key factors underlying the progression of diabetes complications. Our review presents recent knowledge about eicosanoid synthesis and signaling in DM-related complications, and discusses eicosanoid-related target therapeutics.

An inflammatory mediator, prostaglandin E2, in colorectal cancer

It is widely accepted that intake of dietary fats and chronic inflammation are risk factors for developing colorectal cancer. Arachidonic acid is a major component of animal fats, and the bioactive lipids produced from this substrate play critical roles in a variety of biologic processes, including cancer. Cyclooxygenase-derived prostaglandin E2 is a known proinflammatory lipid mediator that promotes tumor progression. Metabolism of arachidonic acid by the cyclooxygenase pathway provides one mechanism for the contribution of dietary fats and chronic inflammation to carcinogenesis. In this review, we highlight recent advances in our understanding of how a proinflammatory mediator prostaglandin E2 promotes colorectal cancer immune evasion. These findings may provide a rationale for the development of new therapeutic approaches to subvert tumor-induced immunosuppression.

The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment

Neutrophils are myeloid cells that constitute 50-70 % of all white blood cells in the human circulation. Traditionally, neutrophils are viewed as the first line of defense against infections and as a major component of the inflammatory process. In addition, accumulating evidence suggest that neutrophils may also play a key role in multiple aspects of cancer biology. The possible involvement of neutrophils in cancer prevention and promotion was already suggested more than half a century ago, however, despite being the major component of the immune system, their contribution has often been overshadowed by other immune components such as lymphocytes and macrophages. Neutrophils seem to have conflicting functions in cancer and can be classified into anti-tumor (N1) and pro-tumor (N2) sub-populations. The aim of this review is to discuss the varying nature of neutrophil function in the cancer microenvironment with a specific emphasis on the mechanisms that regulate neutrophil mobilization, recruitment and activation.

Dexamethasone palmitate ameliorates macrophages-rich graft-versus-host disease by inhibiting macrophage functions

Macrophage infiltration of skin GVHD lesions correlates directly with disease severity, but the mechanisms underlying this relationship remain unclear and GVHD with many macrophages is a therapeutic challenge. Here, we characterize the macrophages involved in GVHD and report that dexamethasone palmitate (DP), a liposteroid, can ameliorate such GVHD by inhibiting macrophage functions. We found that host-derived macrophages could exacerbate GVHD in a mouse model through expression of higher levels of pro-inflammatory TNF-α and IFN-γ, and lower levels of anti-inflammatory IL-10 than resident macrophages in mice without GVHD. DP significantly decreased the viability and migration capacity of primary mouse macrophages compared to conventional dexamethasone in vitro. DP treatment on day 7 and day 14 decreased macrophage number, and attenuated GVHD score and subsequent mortality in a murine model. This is the first study to provide evidence that therapy for GVHD should be changed on the basis of infiltrating cell type.

Active smoking increases microsomal PGE2-synthase-1/PGE-receptor-4 axis in human abdominal aortic aneurysms

Background. The cyclooxygenase- (COX-) 2/microsomal PGE-synthase- (mPGES-) 1/PGE-receptor- (EP-) 4 axis could play a key role in the physiopathology of abdominal aortic aneurysm (AAA) in humans. In this study, we investigated the influence of cardiovascular risk factors on the expression of the PGE₂ pathway in human AAA. Methods. Aortic (n = 89) and plasma (n = 79) samples from patients who underwent AAA repair were collected. Patients were grouped according to risk factors. COX-isoenzymes, mPGES-1, EPs, α-actin, and CD45 and CD68 transcripts levels were quantified by QRT-PCR and plasma PGE₂ metabolites by EIA. Results. Current smoking (CS) patients compared to no-CS had significantly higher local levels of mPGES-1 (P = 0.009), EP-4 (P = 0.007), and PGE₂ metabolites plasma levels (P = 0.008). In the multiple linear regression analysis, these parameters remained significantly enhanced in CS after adding confounding factors. Results from association studies with cell type markers suggested that the increased mPGES-1/EP-4 levels were mainly associated with microvascular endothelial cells. Conclusions. This study shows that elements of the PGE₂ pathway, which play an important role in AAA development, are increased in CS. These results provide insight into the relevance of tobacco smoking in AAA development and reinforce the potential of mPGES-1 and EP-4 as targets for therapy in AAA patients.

Mast cells as targets for immunotherapy of solid tumors

Mast cells have historically been studied mainly in the context of allergic disease. In recent years, we have come to understand the critical importance of mast cells in tissue remodeling events and their role as sentinel cells in the induction and development of effective immune responses to infection. Studies of the role of mast cells in tumor immunity are more limited. The pro-tumorigenic role of mast cells has been widely reported. However, mast cell infiltration predicts improved prognosis in some cancers, suggesting that their prognostic value may be dependent on other variables. Such factors may include the nature of local mast cell subsets and the various activation stimuli present within the tumor microenvironment. Experimental models have highlighted the importance of mast cells in orchestrating the anti-tumor events that follow immunotherapies that target innate immunity. Mast cells are long-lived tissue resident cells that are abundant around many solid tumors and are radiation resistant making them unique candidates for combined treatment modalities. This review will examine some of the key roles of mast cells in tumor immunity, with a focus on potential immunotherapeutic interventions that harness the sentinel role of mast cells.

Implications of chemokine receptors and inflammatory lipids in cancer

Inflammatory lipids receive much attention due to their important biological activities. Knowledge of the chemokine system has also reached a level that makes it interesting in clinics, which prompted clinical trials into compounds manipulating chemokines or their receptors. However, little attention has been devoted to understand the relations between these two systems. Here, we will review the role of inflammatory lipids and chemokines in innate and adaptive immunity with an attempt to link the two systems and with emphasis on their importance in cancer development.

PGE(2) suppression of innate immunity during mucosal bacterial infection

Prostaglandin E2 (PGE2) is an important lipid mediator in inflammatory and immune responses during acute and chronic infections. Upon stimulation by various proinflammatory stimuli such as lipopolysaccharide (LPS), interleukin (IL)-1β, and tumor necrosis factor (TNF)-α, PGE2 synthesis is upregulated by the expression of cyclooxygenases. Biologically active PGE2 is then able to signal through four primary receptors to elicit a response. PGE2 is a critical molecule that regulates the activation, maturation, migration, and cytokine secretion of several immune cells, particularly those involved in innate immunity such as macrophages, neutrophils, natural killer cells, and dendritic cells. Both Gram-negative and Gram-positive bacteria can induce PGE2 synthesis to regulate immune responses during bacterial pathogenesis. This review will focus on PGE2 in innate immunity and how bacterial pathogens influence PGE2 production during enteric and pulmonary infections. The conserved ability of many bacterial pathogens to promote PGE2 responses during infection suggests a common signaling mechanism to deter protective pro-inflammatory immune responses. Inhibition of PGE2 production and signaling during infection may represent a therapeutic alternative to treat bacterial infections. Further study of the immunosuppressive effects of PGE2 on innate immunity will lead to a better understanding of potential therapeutic targets within the PGE2 pathway.

Effects of long-term oral administration of arachidonic acid and docosahexaenoic acid on the immune functions of young rats

Natural killer (NK) cells have many functional activities, including cytotoxicity and the capacity to produce cytokines and chemokines. NK cell activity is regulated partly by eicosanoids, which are produced from arachidonic acid (ARA) and eicosapentaenoic (EPA) acid. In this study, we investigated the effects of long-term therapy with ARA or docosahexaenoic acid (DHA) on the cytotoxic effects of the NK cells of young rats, which were fed on a nonfish oil diet for two generations. Control oil, ARA (240 mg/kg BW/day) or DHA (240 mg/kg BW/day) were orally administrated to the rats for 13 weeks before determining the cytotoxic activity of NK cells from the spleen against YAC-1 mouse lymphoma cell line, as well as the plasma levels of docosanoids or eicosanoids and inflammatory cytokines. Long-term ARA administration significantly suppressed the cytotoxic activity of NK cells. Moreover, ARA administration significantly increased the plasma levels of ARA, prostaglandin (PG) E₂, and PGD₂. However, DHA administration did not produce any different effects compared with those in the control rats. Furthermore, the inflammatory cytokine levels were not affected by the administration of ARA or DHA. These results suggest that long-term ARA administration has an inhibitory effect on the tumor cytotoxicity of NK cells in rat spleen lymphocytes owing to the enhanced synthesis of PGE₂ and PGD₂ from ARA because of the elevated plasma ARA levels in young rats.

Manifestations of immune tolerance in the human female reproductive tract

Like other mucosal surfaces (e.g., the gastrointestinal tract, the respiratory tract), the human female reproductive tract acts as an initial barrier to foreign antigens. In this role, the epithelial surface and subepithelial immune cells must balance protection against pathogenic insults against harmful inflammatory reactions and acceptance of particular foreign antigens. Two common examples of these acceptable foreign antigens are the fetal allograft and human semen/sperm. Both are purposely deposited into the female genital tract and appropriate immunologic response to these non-self antigens is essential to the survival of the species. In light of the weight of this task, it is not surprising that multiple, redundant and overlapping mechanisms are involved. For instance, cells at the immunologic interface between self (female reproductive tract epithelium) and non-self (placental trophoblast cells or human sperm) express glycosylation patterns that mimic those on many metastatic cancer cells and successful pathogens. The cytokine/chemokine milieu at this interface is altered through endocrine and immunologic mechanisms to favor tolerance of non-self. The “foreign” cells themselves also play an integral role in their own immunologic acceptance, since sperm and placental trophoblast cells are unusual and unique in their antigen presenting molecule expression patterns. Here, we will discuss these and other mechanisms that allow the human female reproductive tract to perform this delicate and indispensible balancing act.

Activation of thromboxane A2 receptor (TP) increases the expression of monocyte chemoattractant protein -1 (MCP-1)/chemokine (C-C motif) ligand 2 (CCL2) and recruits macrophages to promote invasion of lung cancer cells

Thromboxane synthase (TXAS) and thromboxane A₂ receptor (TP), two critical components for thromboxane A₂ (TXA₂) signaling, have been suggested to be involved in cancer invasion and metastasis. However, the mechanisms by which TXA₂ promotes these processes are still unclear. Here we show that TXA₂ mimetic, I-BOP, induced monocyte chemoattractant protein -1(MCP-1)/chemokine (C-C motif) ligand 2 (CCL2) expression at both mRNA and protein levels in human lung adenocarcinoma A549 cells stably over-expressing TP receptor α isoform (A549-TPα). The induction of MCP-1 was also found in other lung cancer cells H157 and H460 that express relatively high levels of endogenous TP. Using specific inhibitors of several signaling molecules and promoter/luciferase assay, we identified that transcription factor SP1 mediates I-BOP-induced MCP-1 expression. Furthermore, supernatants from I-BOP-treated A549-TPα cells enhanced MCP-1-dependent migration of RAW 264.7 macrophages. Moreover, co-culture of A549 cells with RAW 264.7 macrophages induced expression of MMPs, VEGF and MCP-1 genes, and increased the invasive potential in A549 cells. These findings suggest that TXA₂ may stimulate invasion of cancer cells through MCP-1-mediated macrophage recruitment.