High Levels Of Prostaglandin E2 Research Articles

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.

GRK2 Mediates Macrophage Polarization by Regulating EP4-cAMP-pCREB Signaling in Ulcerative Colitis and the Therapeutic Effect of Paroxetine on Mice with DSS-Induced Colitis.

G protein-coupled receptor kinase 2 (GRK2) is one of the cytosolic enzymes, and GRK2 translocation induces prostaglandin E2 receptor 4 (EP4) over-desensitization and reduces the level of cyclic adenosine monophosphate (cAMP) to regulate macrophage polarization. However, the role of GRK2 in the pathophysiology of ulcerative colitis (UC) remains unclear. In this study, we investigated the role of GRK2 in macrophage polarization in UC, using biopsies from patients, a GRK2 heterozygous mouse model with dextran sulfate sodium (DSS)-induced colitis, and THP-1 cells. The results showed that a high level of prostaglandin E2 (PGE2) stimulated the receptor EP4 and enhanced the transmembrane activity of GRK2 in colonic lamina propria mononuclear cells (LPMCs), resulting in a down-regulation of membrane EP4 expression. Then, the suppression of cAMP-cyclic AMP responsive element-binding (CREB) signal inhibited M2 polarization in UC. Paroxetine is acknowledged as one of the selective serotonin reuptake inhibitors (SSRI), which is also considered as a potent GRK2 inhibitor with a high selectivity for GRK2. We found that paroxetine could alleviate symptoms of DSS-induced colitis in mice by regulating GPCR signaling to affect macrophage polarization. Taken together, the current results show that GRK2 may act as a novel therapeutic target in UC by regulating macrophage polarization, and paroxetine as a GRK2 inhibitor may have therapeutic effect on mice with DSS-induced colitis.

Prostaglandin E2 involvement in the reproduction of small abalone, Haliotis diversicolor

Prostaglandin E2 (PGE2) has been reported to be involved in reproduction as one of the most abundant and widely distributed prostaglandins in invertebrates. Regulating gonad development and gamete production in mollusks can greatly assist artificial breeding, which is believed to promote the commercial benefits of various mollusk species. In the present study, the contents of PGE2 in the gonads of abalone at different developmental stages (maturing stage, ripe stage, and spawning stage) and reproduction states (before and after spawning) were measured. A higher PGE2 level was found in the gonads of abalones at the ripe stage than other stages, and the highest PGE2 level was detected in the ovaries of female H. diversicolor in the UV-stimulated group. Then the effects of PGE2 injection on the spawning efficiency were explored, and the gamete emission rates of female and male abalone were significantly increased after PGE2 injection. Through qRT-PCR and in situ hybridization assay, higher expression levels and wide distribution of phospholipase A2 (PLA2), cyclooxygenase 2 (COX2), prostaglandin E synthases (PGES2), and prostaglandin E2 receptor 4 (EP4) in the gonads of H. diversicolor were observed after spawning. It is speculated that PGE2 may promote the reproductive cycle in both male and female H. diversicolor, although the regulation mechanism of PGE2 in female and male abalone might be different. The results will be useful for the application of PGE2 in the abalone aquaculture practices to increase the reproduction efficiency in future.

Usefulness of Urinary Biomarkers for Assessing Bladder Condition and Histopathology in Patients with Interstitial Cystitis/Bladder Pain Syndrome.

This study investigated the usefulness of urinary biomarkers for assessing bladder condition and histopathology in patients with interstitial cystitis/bladder pain syndrome (IC/BPS). We retrospectively enrolled 315 patients (267 women and 48 men) diagnosed with IC/BPS and 30 controls. Data on clinical and urodynamic characteristics (visual analog scale (VAS) score and bladder capacity) and cystoscopic hydrodistention findings (Hunner’s lesion, glomerulation grade, and maximal bladder capacity (MBC)) were recorded. Urine samples were utilized to assay inflammatory, neurogenic, and oxidative stress biomarkers, including interleukin (IL)-8, C-X-C motif chemokine ligand 10 (CXCL10), monocyte chemoattractant protein-1 (MCP-1), brain-derived neurotrophic factor (BDNF), eotaxin, IL-6, macrophage inflammatory protein 1 beta (MIP-1β), regulated on activation, normal T cell expressed and secreted (RANTES), tumor necrosis factor-alpha (TNF-α), prostaglandin E2 (PGE2), 8-hydroxy-2′-deoxyguanosine (8-OHdG), and 8-isoproatane, and total antioxidant capacity. Further, specific histopathological findings were identified via bladder biopsy. The associations between urinary biomarker levels and bladder conditions and histopathological findings were evaluated. The results reveal that patients with IC/BPS had significantly higher urinary MCP-1, eotaxin, TNF-α, PGE2, 8-OHdG, and 8-isoprostane levels than controls. Patients with Hunner’s IC (HIC) had significantly higher IL-8, CXCL10, BDNF, eotaxin, IL-6, MIP-1β, and RANTES levels than those with non-Hunner’s IC (NHIC). Patients with NHIC who had an MBC of ≤760 mL had significantly high urinary CXCL10, MCP-1, eotaxin, IL-6, MIP-1β, RANTES, PGE2, and 8-isoprostane levels and total antioxidant capacity. Patients with NHIC who had a higher glomerulation grade had significantly high urinary MCP-1, IL-6, RANTES, 8-OHdG, and 8-isoprostane levels. A significant association was observed between urinary biomarkers and glomerulation grade, MBC, VAS score, and bladder sensation. However, bladder-specific histopathological findings were not well correlated with urinary biomarker levels. The urinary biomarker levels can be useful for identifying HIC and different NHIC subtypes. Higher urinary inflammatory and oxidative stress biomarker levels are associated with IC/BPS. Most urinary biomarkers are not correlated with specific bladder histopathological findings; nevertheless, they are more important in the assessment of bladder condition than bladder histopathology.

Differential distribution of eicosanoids and polyunsaturated fatty acids in the Penaeus monodon male reproductive tract and their effects on total sperm counts

Eicosanoids, which are oxygenated derivatives of polyunsaturated fatty acids (PUFAs), serve as signaling molecules that regulate spermatogenesis in mammals. However, their roles in crustacean sperm development remain unknown. In this study, the testis and vas deferens of the black tiger shrimp Penaeus monodon were analyzed using ultra-high performance liquid chromatography coupled with Orbitrap high resolution mass spectrometry. This led to the identification of three PUFAs and ten eicosanoids, including 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and (±)15-hydroxyeicosapentaenoic acid ((±)15-HEPE), both of which have not previously been reported in crustaceans. The comparison between wild-caught and domesticated shrimp revealed that wild-caught shrimp had higher sperm counts, higher levels of (±)8-HEPE in testes, and higher levels of prostaglandin E2 (PGE2) and prostaglandin F2α in vas deferens than domesticated shrimp. In contrast, domesticated shrimp contained higher levels of (±)12-HEPE, (±)18-HEPE, and eicosapentaenoic acid (EPA) in testes and higher levels of 15d-PGJ2, (±)12-HEPE, EPA, arachidonic acid (ARA), and docosahexaenoic acid (DHA) in vas deferens than wild-caught shrimp. To improve total sperm counts in domesticated shrimp, these broodstocks were fed with polychaetes, which contained higher levels of PUFAs than commercial feed pellets. Polychaete-fed shrimp produced higher total sperm counts and higher levels of PGE2 in vas deferens than pellet-fed shrimp. In contrast, pellet-fed shrimp contained higher levels of (±)12-HEPE, (±)18-HEPE, and EPA in testes and higher levels of (±)12-HEPE in vas deferens than polychaete-fed shrimp. These data suggest a positive correlation between high levels of PGE2 in vas deferens and high total sperm counts as well as a negative correlation between (±)12-HEPE in both shrimp testis and vas deferens and total sperm counts. Our analysis not only confirms the presence of PUFAs and eicosanoids in crustacean male reproductive organs, but also suggests that the eicosanoid biosynthesis pathway may serve as a potential target to improve sperm production in shrimp.

Reduced tumor growth in EP2 knockout mice is related to signaling pathways favoring an increased local anti‑tumor immunity in the tumor stroma.

Inflammatory signaling through prostaglandin E2 receptor subtype 2 (EP2) is associated with malignant tumor growth in both experimental models and cancer patients. Thus, the absence of EP2 receptors in host tissues appears to reduce tumor growth and systemic inflammation by inducing major alterations in gene expression levels across tumor tissue compartments. However, it is not yet well-established how signaling pathways in tumor tissue relate to simultaneous signaling alterations in the surrounding tumor-stroma, at conditions of reduced disease progression due to decreased host inflammation. In the present study, wild-type tumor cells, producing high levels of prostaglandin E2 (MCG 101 cells, EP2+/+), were inoculated into EP2 knockout (EP2−/−) and EP2 wild-type (EP2+/+) mice. Solid tumors were dissected into tumor- and tumor-stroma tissue compartments for RNA expression microarray screening, followed by metabolic pathway analyses. Immunohistochemistry was used to confirm adequate dissections of tissue compartments, and to assess cell proliferation (Ki-67), prostaglandin enzymes (cyclooxygenase 2) and immunity biomarkers (CD4 and CD8) at the protein level. Microarray analyses revealed statistically significant alterations in gene expression in the tumor-stroma compartment, while significantly less pathway alterations occurred in the tumor tissue compartment. The host knockout of EP2 receptors led to a significant downregulation of cell cycle regulatory factors in the tumor-stroma compartment, while interferon γ-related pathways, chemokine signaling pathways and anti-tumor chemokines [chemokine (C-X-C motif) ligand 9 and 10] were upregulated in the tumor compartment. Thus, such gene alterations were likely related to reduced tumor growth in EP2-deficient hosts. On the whole, pathway analyses of both tumor- and tumor-stroma compartments suggested that absence of host EP2 receptor signaling reduces ‘remodeling’ of tumor microenvironments and increase local immunity, probably by decreased productions of stimulating growth factors, perhaps similar to well-recognized physiological observations in wound healing.

Involvement of Proinflammatory Arachidonic Acid (ARA) Derivatives in Crohn's Disease (CD) and Ulcerative Colitis (UC).

Recently, an increase in the incidence of inflammatory bowel disease (IBD) has been observed, especially among children and adolescents. Currently, few studies focus on the differentiation of inflammation in IBD subunits, i.e., Crohn’s Disease (CD) and Ulcerative Colitis (UC). The aim of this study was to compare the concentrations of proinflammatory mediators of arachidonic acid (ARA) and linoleic acid (LA) in patients with CD (n = 34) and UC (n = 30), in order to identify differences in inflammation in both diseases and within the same entity, according to disease activity. Sixty-four adolescents with a mean age of 13.76 ± 2.69 and 14.15 ± 3.31, for CD and UC, respectively, were enrolled in the study. Biochemical analysis of ARA and LA derivatives was performed using a liquid chromatography. A trend was observed in the concentration of 15S-HETE (hydroxyeicosatetraenoic acids) in CD relative to UC. The active phase of both diseases showed a higher 15S-HETE concentration in active CD relative to active UC. Comparing patients with CD with active and inactive disease showed a trend of increased levels of thromboxane B2, leukotriene B4 and 9S-HODE (hydroxyoctadecadienoic acid) in the active versus the inactive disease. We also observed statistically significantly higher levels of 12S-HETE in inactive CD relative to active CD. In the UC group, on the other hand, statistically significantly higher levels of prostaglandin E2 and 16RS-HETE were observed in active UC relative to inactive UC. Moreover, significantly higher concentrations of LTX A4 5S, 6R were observed in inactive UC relative to the active phase. In conclusion, the present study indicated the activity of the 15-LOX pathway in CD. Further studies involving lipid mediators in patients with IBD may contribute to the development of new therapies for the treatment of IBD. The identification of differences in the course of inflammation may help to target therapy in CD and UC, and perhaps allow the introduction of an additional diagnostic marker between the two main IBD subtypes.

Dysregulation of prostaglandins, leukotrienes and lipoxin A4 in bronchiectasis

IntroductionBronchiectasis is characterised by excessive neutrophilic inflammation. Lipid mediators such as prostaglandins and leukotrienes have crucial roles in the inflammatory response. Further characterisation of these lipids and understanding the interplay...

Immunological Traits of Patients with Coexistent Inflammatory Bowel Disease and Periodontal Disease: A Systematic Review.

This systematic review assessed studies that evaluated the immunological traits of patients with both inflammatory bowel disease (IBD) and periodontal disease. An electronic search for literature was conducted on PubMed, Embase, Scopus, Cochrane and Web of Science. Studies that evaluated the immunological response in patients with IBD and periodontal disease were considered eligible for inclusion. A total of 6 cross-sectional studies of 275 patients were included. Immunological analyses were performed in gingival crevicular fluid, saliva, serum, intestinal and gingival biopsies. Four studies identified that the presence of IBD and periodontal disease was associated with higher levels of prostaglandin E2, aMMP8, IL-18 and S100A12, respectively, when compared to patients without the coexistence of both diseases. Furthermore, another study identified higher aMMP-8 levels with increasing severity of periodontitis in Crohn’s disease patients. The quality of overall evidence ranged from high to low due to the observational nature of contributing studies. The coexistence of IBD and periodontal disease seems to be associated with a more responsive inflammatory reaction compared with individuals having one or the other. More randomized controlled studies evaluating the coexistence of IBD and periodontitis are required to better explore the immunological interplay between them.

Change in prostaglandin signaling during sickness syndrome hyperalgesia after ovariectomy in female rats

The present study investigated hyperalgesia during sickness syndrome in female rats. Hyperalgesia was induced by an intraperitoneal injection of lipopolysaccharide (LPS) or an intracerebroventricular injection of prostaglandin E2 (PGE2). No differences were found in basal mechanical and thermal thresholds or in LPS-induced hyperalgesia in sham-operated animals in the diestrus or proestrus phase or in ovariectomized (OVX) animals. However, higher levels of PGE2 where found in the cerebrospinal fluid of OVX animals compared to sham-operated females. Intracerebroventricular injection of PGE2 produced rapid mechanical hyperalgesia in sham-operated rats while these responses were observed at later times in OVX animals. The protein kinase A (PKA) inhibitor H-89 reduced mechanical PGE2-induced hyperalgesia in OVX female rats, whereas no effect was observed in sham-operated animals. In contrast, the exchange protein activated by cyclic adenosine monophosphate (cAMP; Epac) inhibitor ESI-09 reduced mechanical PGE2-induced hyperalgesia, whereas no effect was observed in OVX animals. PGE2 also induced thermal hyperalgesia in sham-operated and OVX female rats and a similar effect of ESI-09 was observed. These results suggest that PGE2-induced hyperalgesia that is observed during sickness syndrome has different signaling mechanisms in cycling and OVX female rats involving the activation of the cAMP-Epac or cAMP-PKA pathways, respectively.

Characterization of the Signaling Modalities of Prostaglandin E2 Receptors EP2 and EP4 Reveals Crosstalk and a Role for Microtubules.

Prostaglandin E2 (PGE2) is a lipid mediator that modulates the function of myeloid immune cells such as macrophages and dendritic cells (DCs) through the activation of the G protein-coupled receptors EP2 and EP4. While both EP2 and EP4 signaling leads to an elevation of intracellular cyclic adenosine monophosphate (cAMP) levels through the stimulating Gαs protein, EP4 also couples to the inhibitory Gαi protein to decrease the production of cAMP. The receptor-specific contributions to downstream immune modulatory functions are still poorly defined. Here, we employed quantitative imaging methods to characterize the early EP2 and EP4 signaling events in myeloid cells and their contribution to the dissolution of adhesion structures called podosomes, which is a first and essential step in DC maturation. We first show that podosome loss in DCs is primarily mediated by EP4. Next, we demonstrate that EP2 and EP4 signaling leads to distinct cAMP production profiles, with EP4 inducing a transient cAMP response and EP2 inducing a sustained cAMP response only at high PGE2 levels. We further find that simultaneous EP2 and EP4 stimulation attenuates cAMP production, suggesting a reciprocal control of EP2 and EP4 signaling. Finally, we demonstrate that efficient signaling of both EP2 and EP4 relies on an intact microtubule network. Together, these results enhance our understanding of early EP2 and EP4 signaling in myeloid cells. Considering that modulation of PGE2 signaling is regarded as an important therapeutic possibility in anti-tumor immunotherapy, our findings may facilitate the development of efficient and specific immune modulators of PGE2 receptors.

Elevated levels of prostaglandin E2 in the tears of patients with severe allergic conjunctivitis and primary cultured conjunctival cells are suppressed by ketotifen and dexamethasone

ObjectiveWe examined the production of prostaglandin E2 (PGE2), which is the key prostaglandin involved in inflammatory disorders of the ocular surface. Tears and conjunctival fibroblasts were evaluated in order to...

Mandibular biomechanical behavior of rats submitted to chronic intermittent or continuous hypoxia and periodontitis.

The aim of this study was to investigate the effects of exposure to continuous (CH) and intermittent (IH) hypoxia on biomechanical properties of the mandible and periodontal tissue of animals submitted to experimental periodontitis (EP) when applying loads in a hypoxic environment. Adult female Wistar rats were exposed during 90 days to IH or CH (simulated high altitude of 4200 m above sea level). Fourteen days prior to the euthanasia, EP was induced to half of the animals of each group. Only in the rats with EP, IH decreased the maximum capacity of the mandible to withstand load and the limit of elastic load. Indicators of intrinsic properties of the bone material were significantly reduced by both types of hypoxia in rats with EP. Hypoxia enhanced the alveolar bone loss induced by EP in the buccal side of the mandible, without showing additional effects in lingual or interradicular bone. Hypoxia increased prostaglandin E2 content in gingival tissue of healthy animals and further elevated the E2 levels increased by EP. When periodontitis is present, hypoxic stress induces a decrease in mineral properties that ultimately affects the ability of the mandible to resist load, mainly during intermittent exposure to hypoxia. These effects on bone may be related to the higher levels of prostaglandin E2 reached in the surrounding gingival tissue. The findings of this study may stimulate strategies to prevent unwanted effects of hypoxia on periodontal tissues.

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.

Mechanisms of the Immunomodulation Effects of Bone Marrow-Derived Mesenchymal Stem Cells on Facial Nerve Injury in Sprague-Dawley Rats.

Normal facial nerve (FN) function is very important for human being. However, if injured, FN function is difficult to restore completely. Recently, many studies reported the immune regulation function of stem cells (SCs). However, the immunomodulation function of SCs on FN injury is still unclear. Our study aims to explore the mechanism of immunomodulation effect of Sprague-Dawley rat bone marrow-derived SCs (BMSCs) on FN injury and specially focus on the regulation of Th17 and the protection effects of BMSCs on central facial motor neurons (FMNs). First, rat FNs were harvested. FN and BMSCs were cultured together or separately and levels of transforming growth factor (TGF)-β1, interleukin (IL)-6, hepatocyte growth factor (HGF), inducible nitric oxide synthase (iNOS), and prostaglandin E2 (PGE2) in supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Then, after treating with or without local BMSCs injection, the proportion of Th17 in neck lymph nodes (LNs) was investigated in rat FN injury models. Furthermore, the apoptotic index of FMNs was studied in rat FN injury models that were treated with or without BMSCs. We found that BMSCs could secrete high levels of IL-6, HGF, PGE2, iNOS, and TGF-β1 in culture. The percentage of Th17 of neck LNs in BMSCs-treated group was significantly lower than that in the control group. The apoptotic index of FMNs in BMSCs-treated group was significantly lower than that in the control group. In conclusion, our research indicates BMSCs could independently secrete cytokines IL-6, HGF, PGE2, iNOS, and TGF-β1, and these cytokines could regulate the balance among subsets of CD4+ T cells and could protect FMNs by inhibiting neuron apoptosis.

The Process of Acclimation to Chronic Hypoxia Leads to Submandibular Gland and Periodontal Alterations: An Insight on the Role of Inflammatory Mediators.

The exposition to hypoxia is a stressful stimulus, and the organism develops acclimation mechanisms to ensure homeostasis, but if this fails, it leads to the development of pathological processes. Considering the large number of people under hypoxic conditions, it is of utmost importance to study the mechanisms implicated in hypoxic acclimation in oral tissues and the possible alteration of some important inflammatory markers that regulate salivary and periodontal function. It is the aim of the present study to analyze submandibular (SMG) and periodontal status of animals chronically exposed to continuous (CCH) or intermittent (CIH) hypoxia in order to elucidate the underlying molecular mechanisms that may lead to hypoxic acclimation. Adult Wistar rats were exposed to CCH or CIH simulating 4200 meters of altitude during 90 days. Salivary secretion was decreased in animals exposed to hypoxia, being lower in CIH, together with increased prostaglandin E2 (PGE2) content, TBARS concentration, and the presence of apoptotic nuclei and irregular secretion granules in SMG. AQP-5 mRNA levels decreased in both hypoxic groups. Only the CCH group showed higher HIF-1α staining, while CIH alone exhibited interradicular bone loss and increased concentration of the bone resorption marker CTX-I. In summary, animals exposed to CIH show a worse salivary secretion rate, which related with higher levels of PGE2, suggesting a negative role of this inflammatory mediator during hypoxia acclimation. We link the weak immunorreactivity of HIF-1α in CIH with improper hypoxia acclimation, which is necessary to sustaining SMG physiology under this environmental condition. The alveolar bone loss observed in CIH rats could be due mainly to a direct effect of PGE2, as suggested by its higher content in gingival tissue, but also to the indirect effect of hyposalivation. This study may eventually contribute to finding therapeutics to treat the decreased salivary flow, improving in that way oral health.

Preconditioning of bone marrow-derived mesenchymal stem cells highly strengthens their potential to promote IL-6-dependent M2b polarization

BackgroundDuring the last decade, mesenchymal stem cells (MSCs) have gained much attention in the field of regenerative medicine due to their capacity to differentiate into different cell types and to promote immunosuppressive effects. However, the underlying mechanism of MSC-mediated immunoregulation is not fully understood so far. Macrophages are distinguished in classical activated, pro-inflammatory M1 and alternatively activated M2 cells, which possess different functions and transcriptional profiles with respect to inflammatory responses. As polarization is not fixed, macrophage functional plasticity might be modulated by the microenvironment allowing them to rapidly react to danger signals and maintaining tissue homeostasis.MethodsMurine MSCs were preconditioned with IL-1ß and IFN-ɣ to enhance their immunosuppressive capacity regarding macrophage polarization under M1- and M2a-polarizing conditions. Macrophage polarization was analyzed by real-time PCR, flow cytometry, and cytokine detection in culture supernatants. The role of MSC-derived nitric oxide (NO), prostaglandin E2 (PGE2), and IL-6 in this process has been evaluated using siRNA transfection and IL-6 receptor-deficient macrophages, respectively.ResultsPreconditioned, but not unprimed, MSCs secreted high levels of NO, IL-6, and PGE2. Co-culture with macrophages (M0) in the presence of M1 inducers (LPS + IFN-ɣ) led to significant reduction of CD86 and iNOS protein in macrophages and diminished TNF-α secretion. Additionally, CD86 and iNOS protein expression as well as NO and IL-10 secretion were markedly increased under M2a-polarizing culture conditions (IL-4). MSC-dependent macrophage polarization did not depend on direct cell-cell contact. Co-culturing in the presence of LPS and IFN-ɣ resulted in the upregulation of M2a, M2b, and M2c marker genes, whereas in the presence of IL-4 only M2b markers were significantly increased. In turn, IL-10-producing regulatory M2b cells significantly inhibited IFN-ɣ expression in CD4+ T lymphocytes. Finally, we show that MSC-mediated macrophage polarization strongly depends on IL-6, whereas a minor role for NO and PGE2 was found.ConclusionsPreconditioning of MSCs highly strengthens their capacity to regulate macrophage features and to promote immunosuppression. Repression of M1 polarization during inflammation and M2b polarization under anti-inflammatory conditions strongly depend on functional IL-6 signaling in macrophages. The potential benefit of preconditioned MSCs and IL-6 should be considered for future clinical treatment.

Commensal dysbiosis modulates the tumor microenvironment in breast cancer and diminishes efficacy of PD-L1 inhibition

Abstract For patients with HR+ breast cancer, non-responsiveness to PD-1/PD-L1 blockade cannot be attributed to poor immunogenicity, as immune-stimulatory gene signatures are associated with greater long-term survival and enhanced responsiveness to therapy. Targeting myeloid-driven immune suppression has also been shown to enhance efficacy of PD-L1 blockade in non-responsive tumors. However, we find that in HR+ breast cancer, synergy with PD-L1 blockade is negatively influenced by a pre-established loss of commensal homeostasis, or commensal dysbiosis. Using a clinically relevant non-responsive HR+ breast tumor model, establishing commensal dysbiosis prior to breast tumor initiation drives significant and irreversible T cell dysfunction within primary tumors. Additionally, commensal dysbiosis alters the cellular composition within the tumor microenvironment, culminating in the recruitment and polarization of M2-like macrophages with distinct tumor-suppressive attributes. Systemically, tumor-bearing animals with established commensal dysbiosis have significantly higher levels of prostaglandin E2 with the serum, which is independent of tumor volume. However, blockade of COX-2 only synergizes with PD-L1 blockade in animals without commensal dysbiosis. Unexpectedly, we found that commensal dysbiosis enhances COX-1/PGE2 signaling within the mammary epithelium during early tumor progression. Inhibition of COX-1-mediated PGE2 synthesis during early stages of tumor progression resulted in delayed tumor progression only in dysbiotic tumor-bearing mice, suggesting that dysbiosis-induced COX-1 mediated tissue inflammation is sufficient to drive irreversible immune suppression during advanced breast cancer.

ApoL1 renal risk variants induce aberrant THP-1 monocyte differentiation and increase eicosanoid production via enhanced expression of cyclooxygenase-2.

Apolipoprotein L1 ( ApoL1) genetic variants are strongly associated with kidney diseases. We investigated the role of ApoL1 variants in monocyte differentiation and eicosanoid production in macrophages, as activated tissue macrophages in kidney might contribute to kidney injury. In human monocyte THP-1 cells, transient overexpression of ApoL1 (G0, G1, G2) by transfection resulted in a 5- to 11-fold increase in CD14 and CD68 gene expression, similar to that seen with phorbol-12-myristate acetate treatment. All ApoL1 variants caused monocytes to differentiate into atypical M1 macrophages with marked increase in M1 markers CD80, TNF, IL1B, and IL6 and modest increase in the M2 marker CD163 compared with control cells. ApoL1-G1 transfection induced additional CD206 and TGFB1 expression, and ApoL1-G2 transfection induced additional CD204 and TGFB1 expression. Gene expression of prostaglandin E2 (PGE2) synthase and thromboxane synthase and both gene and protein expression of cyclooxygenase-2 (COX-2) were increased by ApoL1-G1 and -G2 variants compared with -G0 transfection. Higher levels of PGE2 and thromboxane B2, a stable metabolite of thromboxane A2, and transforming growth factor (TGF)-β1 were released into the supernatant of cultured THP-1 cells transfected with ApoL1-G1 and -G2, but not -G0. The increase in PGE2, thromboxane B2, and TGF-β1 was inhibited by COX-2-specific inhibitor CAY10404 but not by COX-1-specific inhibitor SC-560. These results demonstrate a novel role of ApoL1 variants in the regulation of monocyte differentiation and eicosanoid metabolism, which could modify the immune response and promote inflammatory signaling within the local targeted organs and tissues including the kidney.

Elevated serum prostaglandin E2 predicts the risk of infection in hepatitis B virus-related acute-on-chronic liver failure patients.

To evaluate the serum Prostaglandin E2 (PGE2) level in Acute-on-chronic liver failure (ACLF) and determine its predicative value for infection. From April 2014 to April 2015, ninety-one patients with hepatitis B virus and ACLF but without infection were enrolled into this prospective study that was carried out at our Hospital. Twenty patients with stable chronic hepatitis B were enrolled from the outpatient department and twenty healthy control subjects without any disease were enrolled from hospital staff. Serum PGE2 levels were determined using ELISA at enrollment. Clinical and laboratory parameters were collected. Receiver operating characteristic (ROC) curves were used to determine optimal cut-off values to predict infection. Significantly higher PGE2 levels were found in patients with ACLF in comparison with healthy controls and patients with stable CHB (P<0.0001). In ACLF patients, PGE2 levels were significantly higher in patients that eventually developed infection than those without this complication (P<0.0001). ROC analysis showed that serum PGE2 (area under the ROC curve, 0.83) could predict infection in patients with ACLF with sensitivity of 78.4% and specificity of 81.5% using a threshold of 141pg/mL. Serum PGE2 is associated with the susceptibility to secondary infections for patients with ACLF. Increased PGE2 serum levels may serve as a potential biomarker for developing infections in ACLF patients.