Effects of PGI2 analogues on Th1- and Th2-related chemokines in monocytes via epigenetic regulation

The IL-4/13-induced production of M2 chemokines by human lung macrophages is enhanced by adenosine and PGE2

BACKGROUND AND PURPOSE

Lung macrophages (LMs) are critically involved in respiratory diseases. The primary objective of the present study was to determine whether or not an adenosine analog (NECA) and prostaglandin E2 (PGE2) affected the interleukin (IL)-4- and IL-13-induced release of M2a chemokines (CCL13, CCL17, CCL18, and CCL22) by human LMs.

EXPERIMENTAL APPROACH

Primary macrophages isolated from resected human lungs were incubated with NECA, PGE2, roflumilast, or vehicle and stimulated with IL-4 or IL-13 for 24 h. The levels of chemokines and PGE2 in the culture supernatants were measured using ELISAs and enzyme immunoassays.

KEY RESULTS

Exposure to IL-4 (10 ng/mL) and IL-13 (50 ng/mL) was associated with greater M2a chemokine production but not PGE2 production. PGE2 (10 ng/mL) and NECA (10-6 M) induced the production of M2a chemokines to a lesser extent but significantly enhanced the IL-4/IL-13-induced production of these chemokines. At either a clinically relevant concentration (10-9 M) or at a concentration (10-7 M) that fully inhibited phosphodiesterase 4 (PDE4) activity, roflumilast did not increase the production of M2a chemokines and did not modulate their IL-13-induced production, regardless of the presence or absence of PGE2.

CONCLUSIONS

NECA and PGE2 enhanced the IL-4/IL-13-induced production of M2a chemokines. The inhibition of PDE4 by roflumilast did not alter the production of these chemokines. These results contrast totally with the previously reported inhibitory effects of NECA, PGE2, and PDE4 inhibitors on the lipopolysaccharide-induced release of tumor necrosis factor alpha and M1 chemokines in human LMs.

Suppressive Effects of 4-(Phenylsulfanyl) Butan-2-One on CCL-1 Production via Histone Acetylation in Monocytes

The 4-(phenylsulfanyl) butan-2-one (4-PSB-2), a marine-derived compound from soft coral, was proven to have multiple biological activities including neuroprotection and potent anti-inflammatory effects. CC chemokine ligand (CCL)-1 belongs to T helper (Th)2-related chemokines that are involved in the recruitment of Th2 inflammatory cells. Histone acetylation has been recognized as a critical mechanism underlying the regulated cytokine and chemokine production. Our study tried to investigate the anti-inflammatory effect of 4-PSB-2 on CCL-1 production in human monocytes and explore possible underlying intracellular processes, including epigenetic regulation. To confirm our hypothesis, human monocyte THP-1 cell line and primary CD14⁺ cells were pretreated with various concentrations of 4-PSB-2 and then were stimulated with lipopolysaccharide (LPS). The CCL-1 concentration was measured by enzyme-linked immunosorbent assays, and the intracellular signaling pathways and epigenetic regulation of 4-PSB-2 were investigated by using Western blotting and chromatin immunoprecipitation analysis. In this study, we found that 4-PSB-2 had a suppressive effect on LPS-induced CCL-1 production. Moreover, this suppressive effect of 4-PSB-2 was mediated via intracellular signaling such as the mitogen-activated protein kinase and nuclear factor-κB pathways. In addition, 4-PSB-2 could suppress CCL-1 production by epigenetic regulation through downregulating histone H3 and H4 acetylation. In short, our study demonstrated that 4-PSB-2 may have a potential role in the treatment of allergic inflammation.

Periodontitis Salivary Microbiota Worsens Colitis

Evidence suggests that periodontitis contributes to the pathogenesis of inflammatory bowel disease, including Crohn's disease and ulcerative colitis. However, few studies have examined the role of swallowing and saliva in the pathogenesis of gastrointestinal diseases. Saliva contains an enormous number of oral bacteria and is swallowed directly into the intestine. Here, we explored the influence of periodontitis salivary microbiota on colonic inflammation and possible mechanisms in dextran sulfate sodium (DSS)-induced colitis. The salivary microbiota was collected from healthy individuals and those with periodontitis and gavaged to C57BL/6 mice. Periodontitis colitis was induced by DSS for 5 d and ligature for 1 wk. The degree of colon inflammation was evaluated through hematoxylin and eosin staining, ELISA, and quantitative real-time polymerase chain reaction. Immune parameters were measured with quantitative real-time polymerase chain reaction, flow cytometry, and immunofluorescence. The gut microbiota and metabolome analyses were performed via 16S rRNA gene sequencing and liquid chromatography-mass spectrometry. Although no significant colitis-associated phenotypic changes were found under physiologic conditions, periodontitis salivary microbiota exacerbated colitis in a periodontitis colitis model after DSS induction. The immune response more closely resembled the pathology of ulcerative colitis, including aggravated macrophage M2 polarization and Th2 cell induction (T helper 2). Inflammatory bowel disease-associated microbiota, such as Blautia, Helicobacter, and Ruminococcus, were changed in DSS-induced colitis after periodontitis salivary microbiota gavage. Periodontitis salivary microbiota decreased unsaturated fatty acid levels and increased arachidonic acid metabolism in DSS-induced colitis, which was positively correlated with Aerococcus and Ruminococcus, suggesting the key role of these metabolic events and microbes in the exacerbating effect of periodontitis salivary microbiota on experimental colitis. Our study demonstrated that periodontitis contributes to the pathogenesis of colitis through the swallowing of salivary microbiota, confirming the role of periodontitis in systemic disease and providing new insights into the etiology of gastrointestinal inflammatory diseases.

The lysine methyltransferase SETD2 is a dynamically expressed regulator of early neural crest development

SETD2 is a histone H3 lysine 36 (H3K36) tri-methylase that is upregulated in response to neural crest induction. Because the H3K36 di-methylase NSD3 and cytoplasmic non-histone protein methylation are necessary for neural crest development, we investigated the expression and requirement for SETD2 in the neural crest. SetD2 is expressed throughout the chick blastoderm beginning at gastrulation. Subsequently, SetD2 mRNA becomes restricted to the neural plate, where it is strongly and dynamically expressed as neural tissue is regionalized and cell fate decisions are made. This includes expression in premigratory neural crest cells, which is downregulated prior to migration. Likely due to the early onset of its expression, SETD2 morpholino knockdown does not significantly alter premigratory Sox10 expression or neural crest migration; however, both are disrupted by a methyltransferase mutant SETD2 construct. These results suggest that SETD2 activity is essential for early neural crest development, further demonstrating that lysine methylation is an important mechanism regulating the neural crest.

Profiling NSD3-dependent neural crest gene expression reveals known and novel candidate regulatory factors

The lysine methyltransferase NSD3 is required for the expression of key neural crest transcription factors and the migration of neural crest cells. Nevertheless, a complete view of the genes dependent upon NSD3 for expression and the developmental processes impacted by NSD3 in the neural crest was lacking. We used RNA sequencing (RNA-seq) to profile transcripts differentially expressed after NSD3 knockdown in chick premigratory neural crest cells, identifying 674 genes. Gene Ontology and gene set enrichment analyses further support a requirement for NSD3 during neural crest development and show that NSD3 knockdown also upregulates ribosome biogenesis. To validate our results, we selected three genes not previously associated with neural crest development, Astrotactin 1 (Astn1), Dispatched 3 (Disp3), and Tropomyosin 1 (Tpm1). Using whole mount in situ hybridization, we show that premigratory neural crest cells express these genes and that NSD3 knockdown downregulates (Astn1 and Disp3) and upregulates (Tpm1) their expression, consistent with RNA-seq results. Altogether, this study identifies novel putative regulators of neural crest development and provides insight into the transcriptional consequences of NSD3 in the neural crest, with implications for cancer.

The role of GLS1-mediated glutaminolysis/2-HG/H3K4me3 and GSH/ROS signals in Th17 responses counteracted by PPARγ agonists

Background: Peroxisome proliferator-activated receptor gamma (PPARγ) has the ability to counter Th17 responses, but the full mechanisms remain elusive. Herein, we aimed to elucidate this process in view of cellular metabolism, especially glutaminolysis.

Methods: MTT, CCK-8, Annexin V-FITC/PI staining or trypan blue exclusion assays were used to analyze cytotoxicity. Flow cytometry and Q-PCR assays were applied to determine Th17 responses. The detection of metabolite levels using commercial kits and rate-limiting enzyme expression using western blotting assays was performed to illustrate the metabolic activity. ChIP assays were used to examine H3K4me3 modifications. Mouse models of dextran sulfate sodium (DSS)-induced colitis and house dust mite (HDM)/lipopolysaccharide (LPS)-induced asthma were established to confirm the mechanisms studied in vitro.

Results: The PPARγ agonists rosiglitazone and pioglitazone blocked glutaminolysis but not glycolysis under Th17-skewing conditions, as indicated by the detection of intracellular lactate and α-KG and the fluorescence ratios of BCECF-AM. The PPARγ agonists prevented the utilization of glutamine and thus directly limited Th17 responses even when Foxp3 was deficient. The mechanisms were ascribed to restricted conversion of glutamine to glutamate by reducing the expression of the rate-limiting enzyme GLS1, which was confirmed by GLS1 overexpression. Replenishment of α-KG and 2-HG but not succinate weakened the effects of PPARγ agonists, and α-KG-promoted Th17 responses were dampened by siIDH1/2. Inhibition of KDM5 but not KDM4/6 restrained the inhibitory effect of PPARγ agonists on IL-17A expression, and the H3K4me3 level in the promoter and CNS2 region of the il-17 gene locus down-regulated by PPARγ agonists was rescued by 2-HG and GLS1 overexpression. However, the limitation of PPARγ agonists on the mRNA expression of RORγt was unable to be stopped by 2-HG but was attributed to GSH/ROS signals subsequent to GLS1. The exact role of PPARγ was proved by GW9662 or PPARγ knockout, and the mechanisms for PPARγ-inhibited Th17 responses were further confirmed by GLS1 overexpression in vivo.

Conclusion: PPARγ agonists repressed Th17 responses by counteracting GLS1-mediated glutaminolysis/2-HG/H3K4me3 and GSH/ROS signals, which is beneficial for Th17 cell-related immune dysregulation.

Epigenetic silencing of chemokine CCL2 represses macrophage infiltration to potentiate tumor development in small cell lung cancer

Highly invasive and rapidly fatal, small-cell lung cancer (SCLC) has been an insurmountable gulf since discovery. Innate immunity plays a vital role in anti-tumor response, among which macrophages contribute to an indispensable character. Here, we found that macrophage infiltration in SCLC reduced significantly in a stage-dependent manner, attributed to the decreased expression of CCL2, a potent chemoattractant for monocytes. Validated by ChIP-qPCR and MassArray methylation analysis, CCL2 expression was inhibited by EZH2-mediated H3K27me3 in the enhancer regions and DNMT1-mediated DNA methylation in the promoter regions, the process of which could be reversed by small-molecular compounds, EPZ011989 and Decitabine. Direct cell-cell contact between SCLC cells and macrophages skewed the phenotype of macrophages to be more M1-like. Furthermore, in an ectopic engraft model of SCLC, disruption of EZH2/DNMT1 function using the combination treatment of EPZ011989 and Decitabine potently abrogated the inhibition of macrophage infiltration and thus suppressed tumor growth, the effect of which was impaired by CCL2 neutralization or macrophage depletion. Overall, this work provides new insights into the role of macrophages in SCLC and establishes a rationale for constructing novel therapeutic avenues for SCLC patients.

Anti-colonic Inflammation by Black Raspberries through Regulating Toll-like Receptor-4 Signaling in Interlukin-10 Knockout Mice

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon, with a steadily rising prevalence in Western and newly industrialized countries. UC patients have a cancer incidence as high as 10% after 20 years of the disease. Although the importance of fruits and vegetables in defense against UC is beginning to be appreciated, the mechanisms remain largely unclear. In the current study, we reported that dietary black raspberries (BRBs) decreased colonic inflammation in the mucosa and submucosa of interleukin (IL)-10 knockout (KO) mice. We then used colon, spleen, and plasma from those mice to investigate whether BRBs exert their anti-inflammatory effects by correcting dysregulated toll-like receptor (TLR)-4 signaling to downregulate prostaglandin E2 (PGE2). Other studies reported that spleen is the reservoir of macrophages and depletion of macrophages in IL-10 KO mice prevents the development of colitis. Our results showed that BRBs decreased the percentages of macrophages in spleens of IL-10 KO mice. Moreover, mechanistically, the BRB diet corrected dysregulated TLR-4 signaling in cells from the colon and spleen, decreased PGE2 and prostaglandin I2, and increased 15-lipoxygenase and its product, 13-S-hydroxyoctadecadienoic acid, in plasma of IL-10 KO mice. Therefore, we have elucidated one of the anti-inflammatory mechanisms of BRBs, and have identified biomarkers that could be indicators of response in UC patients treated with them. Our findings with BRBs could well apply to many other commonly consumed fruits and vegetables.

Azithromycin suppresses Th1- and Th2-related chemokines IP-10/MDC in human monocytic cell line

BACKGROUND

Cytokines and chemokines play critical roles in the pathogenesis of asthma. Azithromycin, a macrolides, is frequently used in asthmatic children with lower respiratory tract infection and is reported having anti-inflammatory and immunomodulatory effects. However, the effects of azithromycin on the expression of TNF-α, Th1- and Th2-related chemokines, and neutrophil chemoattractant are unknown. We investigated the in vitro effects of azithromycin on the expression of TNF-α, Th1-related chemokine interferon-γ-inducible protein-10 (IP-10/CXCL10), Th2-related chemokine macrophage-derived chemokine (MDC/CCL22) and neutrophil chemoattractant growth-related oncogene-α (GRO-α/CXCL1) in THP-1 cells as a model for human monocytes.

METHODS

THP-1 cells were pretreated with various concentrations of azithromycin before Toll-like receptor 4 (TLR4) agonist lipopolysaccharide (LPS) stimulation. TNF-α, IP-10, MDC and GRO-α were measured by ELISA. Intracellular signaling was investigated by pathway inhibitors and Western blot.

RESULT

Azithromycin suppressed MDC and IP-10 expression in LPS-stimulated THP-1 cells. However, azithromycin had no effect LPS-induced TNF-α and GRO-α expression. Western blotting revealed that azithromycin suppressed LPS-induced phosphorylation of mitogen-activated protein kinase (MAPK)-JNK and ERK expression, and also suppressed LPS-induced phosphorylation of nuclear factor (NF) κB-p65 expression.

CONCLUSION

Azithromycin suppressed LPS-induced MDC expression via the MAPK-JNK and the NFκB-p65 pathway. Azithromycin also suppressed LPS-induced IP-10 via the MAPK-JNK/ERK and the NFκB-p65 pathway. Azithromycin may benefit asthmatic patients by suppressing chemokines expression.

The effects of acarbose on chemokine and cytokine production in human monocytic THP-1 cells

BACKGROUND AND OBJECTIVES

Chronic inflammation induced by proinflammatory cytokines and chemokines is postulated to be involved in insulin resistance and β-cell dysfunction in type 2 diabetes mellitus (T2DM). Acarbose, the α-glucosidase inhibitor, is an oral antidiabetic drug for T2DM. Acarbose suppresses inflammatory cytokine production in patients with T2DM, though the underlying mechanisms are unclear. In the present study, we aimed to investigate the anti-inflammatory effects and the exact mechanisms of acarbose in human monocytic THP-1 cells.

METHODS

THP-1 cells were pretreated with acarbose and then stimulated with lipopolysaccharide (LPS). The levels of Th1-related chemokines, including interferon-γ-inducible protein-10 (IP-10), monocyte chemoattractant protein-1 (MCP-1), Th2-related chemokine macrophage-derived chemokine (MDC), and proinflammatory cytokine tumor necrosis factor-α (TNF-α), were determined by enzyme-linked immunosorbent assay. Intracellular signaling pathways were explored by Western blot analysis and using a chromatin immunoprecipitation assay.

RESULTS

Acarbose suppressed the levels of IP-10, MCP-1, MDC, and TNF-α and downregulated phosphorylation of p38, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and nuclear factor-kappa B-p65 (NF-κB-p65) in LPS-stimulated THP-1 cells. Acarbose suppressed LPS-induced acetylation of histones H3 (H3) and H4 in the IP-10 and MCP-1 promoter regions. These findings revealed the suppressive effects of acarbose on IP-10, MCP-1, MDC, and TNF-α production in THP-1 cells via, at least partially, the p38, JNK, ERK, and NF-κB-p65 pathways, as well as through epigenetic regulation via histone H3 and H4 acetylation.

CONCLUSION

Our study points to the therapeutic anti-inflammatory potential of acarbose.

Suppressive effects of metformin on T-helper 1-related chemokines expression in the human monocytic leukemia cell line THP-1

PURPOSE OF THE STUDY

Type 1 and type 2 diabetes mellitus (DM) are chronic T-cell-mediated inflammatory diseases. Metformin is a widely used drug for type 2 DM that reduces the need for insulin in type 1 DM. However, whether metformin has an anti-inflammatory effect for treating DM is unknown. We investigated the anti-inflammatory mechanism of metformin in the human monocytic leukemia cell line THP-1.

MATERIALS AND METHODS

The human monocytic leukemia cell line THP-1 was pretreated with metformin and stimulated with lipopolysaccharide (LPS). The production of T-helper (Th)-1-related chemokines including interferon-γ-induced protein-10 (IP-10) and monocyte chemoattractant protein-1 (MCP-1), Th2-related chemokine macrophage-derived chemokine, and the proinflammatory chemokine tumor necrosis factor-α was measured using enzyme-linked immunosorbent assay. Intracellular signaling pathways were investigated using Western blot analysis and chromatin immunoprecipitation assay.

RESULTS

Metformin suppressed LPS-induced IP-10 and MCP-1 production as well as LPS-induced phosphorylation of c-Jun N-terminal kinase (JNK), p38, extracellular signal-regulated kinase (ERK), and nuclear factor-kappa B (NF-κB). Moreover, metformin suppressed LPS-induced acetylation of histones H3 and H4 at the IP-10 promoter.

CONCLUSIONS

Metformin suppressed the production of Th1-related chemokines IP-10 and MCP-1 in THP-1 cells. Suppressive effects of metformin on IP-10 production might be attributed at least partially to the JNK, p38, ERK, and NF-κB pathways as well as to epigenetic regulation through the acetylation of histones H3 and H4. These results indicated the therapeutic anti-inflammatory potential of metformin.

Long-acting β2-adrenoreceptor agonists suppress type 1 interferon expression in human plasmacytoid dendritic cells via epigenetic regulation

The combination of inhaled long-acting β2-adrenoreceptor (LABA) and inhaled glucocorticoid (ICS) is a major therapy for asthma. However, the increased risk of infection is still a concern. Plasmacytoid dendritic cells (pDCs) are the predominant cells producing type 1 interferon (IFN) against infection. The effect of LABA/ICS on type 1 IFN expression in human pDCs is unknown. Circulating pDCs were isolated from healthy human subjects and were pretreated with glucocorticoid (GCS), LABA or a cAMP analog, and were stimulated with Toll-like receptor (TLR) agonist CpG (TLR9) or imiquimod (TLR7) in the presence of IL-3. The expression of type 1 IFN (IFN-α/β) were measured by ELISA. The mechanisms were investigated using receptor antagonists, pathway inhibitors, Western blotting and chromatin immunoprecipitation. GCS suppressed TLR-induced IFN-α expression, and LABA enhanced the suppressive effect. LABA alone also suppressed TLR-induced IFN-α/β expression, and the effect was reversed by the β2-adrenoreceptor antagonist ICI118551. Dibutyryl-cAMP, a cAMP analog, conferred a similar suppressive effect, and the effect was abrogated by the exchange protein directly activated by cAMP (Epac) inhibitor HJC0197 or intracellular free Ca²⁺ chelator BAPTA-AM. Formoterol suppressed TLR-induced phosphorylation of mitogen-activated protein kinase (MAPK)-p38/ERK. Formoterol suppressed interferon regulatory factor (IRF)-3/IRF-7 expression. Formoterol suppressed CpG-induced translocation of H3K4 specific methyltransferase WDR5 and suppressed H3K4 trimethylation in the IFNA and IFNB gene promoter region. LABA suppressed TLR7/9-induced type 1 IFNs production, at least partly, via the β₂-adrenoreceptor-cAMP-Epac-Ca²⁺, IRF-3/IRF-7, the MAPK-p38/ERK pathway, and epigenetic regulation by suppressing histone H3K4 trimethylation through inhibiting the translocation of WDR5 from cytoplasm to nucleus. LABA may interfere with anti-viral immunity.

Tumor necrosis factor-alpha inhibitors suppress CCL2 chemokine in monocytes via epigenetic modification

The treatment of rheumatoid arthritis (RA) with tumor necrosis factor-alpha (TNF-α) inhibitors could lead to adverse effects. Therefore, the identification of downstream therapeutic targets is important. Monocyte chemoattractant protein-1 (MCP-1, also called CCL2) is related to RA disease activity, and epigenetic modifications are hypothesized to regulate gene expression in RA pathogenesis. We studied the effects of two TNF-α inhibitors, etanercept and adalimumab, on CCL2 expression and the potentially associated intracellular mechanisms, including epigenetic regulation. Etanercept and adalimumab decreased CCL2 production in THP-1 cells and human primary monocytes, as detected using enzyme-linked immunosorbent assays, and these changes in the CCL2 levels were independent of the TNF-α levels. Etanercept and adalimumab suppressed mitogen-activated protein kinase (MAPK) phospho-p38, phospho-JNK, phospho-ERK and nuclear factor-κB (NF-κB) phospho-p65, as demonstrated using western blot analyses. The investigation of epigenetic modifications using chromatin immunoprecipitation revealed that etanercept and adalimumab down-regulated acetylation of histone (H)3 and H4 in the CCL2 promoter region by decreasing the recruitment of the NF-κB associated acetyltransferases p300, CBP and PCAF. Etanercept and adalimumab also down-regulated trimethylation of H3K4, H3K27, H3K36 and H3K79 in the CCL2 promoter region by decreasing the expression of the related methyltransferases WDR5 and Smyd2. We demonstrated that TNF-α inhibitors exert immunomodulatory effects on CCL2 expression in human monocytes via MAPKs, NF-κB and epigenetic modifications. These findings broaden the mechanistic knowledge related to TNF-α inhibitors and provide novel therapeutic targets for RA.

Prostaglandin I2 Suppresses Proinflammatory Chemokine Expression, CD4 T Cell Activation, and STAT6-Independent Allergic Lung Inflammation

Allergic airway diseases are immune disorders associated with heightened type 2 immune responses and IL-5 and IL-13 production at the site of inflammation. We have previously reported that cyclooxygenase (COX) inhibition by indomethacin augmented allergic airway inflammation in a STAT6-independent manner. However, the key COX product(s) responsible for restraining indomethacin-mediated STAT6-independent allergic inflammation is unknown. In this study, using the mouse model of OVA-induced allergic airway inflammation, we identified that PGI2 receptor (IP) signaling was critical for indomethacin-induced, STAT6-independent proallergic effects. We demonstrated that IP deficiency increased inflammatory cell infiltration, eosinophilia, and IL-5 and IL-13 expression in the lung in a STAT6-independent manner. The augmented STAT6-independent allergic inflammation correlated with enhanced primary immune responses to allergic sensitization and elevated production of multiple inflammatory chemokines (CCL11, CCL17, CCL22, and CXCL12) in the lung after allergen challenge. We also showed that the PGI2 analogue cicaprost inhibited CD4 T cell proliferation and IL-5 and IL-13 expression in vitro, and IP deficiency diminished the stimulatory effect of indomethacin on STAT6-independent IL-5 and IL-13 responses in vivo. The inhibitory effects of PGI2 and the IP signaling pathway on CD4 T cell activation, inflammatory chemokine production, and allergic sensitization and airway inflammation suggest that PGI2 and its analogue iloprost, both Food and Drug Administration-approved drugs, may be useful in treating allergic diseases and asthma. In addition, inhibiting PGI2 signaling by drugs that either block PGI2 production or restrain IP signaling may augment STAT6-independent pathways of allergic inflammation.

Cysteinyl leukotriene receptor antagonist epigenetically modulates cytokine expression and maturation of human myeloid dendritic cells

BACKGROUND

Cysteinyl leukotriene receptor antagonists are important controllers in treating asthma. Human myeloid DCs (mDCs) play critical roles in the pathogenesis of asthma. However, the effects of cysteinyl leukotriene receptor antagonist on human mDCs are unknown.

METHODS

To investigate the effects of cysteinyl leukotriene receptor antagonist on the function of human mDCs, circulating mDCs were isolated from six health subjects. Human mDCs were pretreated with montelukast and were stimulated with toll-like receptor (TLR) ligands lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (poly I:C). Tumor necrosis factor (TNF)-α and interleukin (IL)-10 were measured by ELISA. Intracellular signaling was investigated by pathway inhibitors, western blot and chromatin immunoprecipitation. Costimulatory molecules expression was investigated by flow cytometry. T cell polarization function of mDCs was investigated by measuring interferon (IFN)-γ, IL-13, IL-10 and IL-17A production by T cells using mDC/T cell coculture assay.

RESULTS

Montelukast suppressed TLR-mediated TNF-α expression via the NFκB-p65 and mitogen-activated protein kinase (MAPK)-JNK pathway, and enhanced TLR-mediated IL-10 expression via the MAPK-p38 pathway and epigenetic regulation by histone H3 acetylation. Montelukast suppressed LPS-induced CD80, CD86, CD40 and HLA-DR expression. Montelukast-treated mDCs suppressed IFN-γ and IL-13 production by T cells.

CONCLUSION

Cysteinyl leukotriene receptor antagonist alters the function of human mDCs by epigenetically modulating cytokine expression, suppressing costimulatory molecules expression and inhibiting the ability to initiate Th1/Th2 responses. The effects of cysteinyl leukotriene receptor antagonist on human mDCs can be an important mechanism in treating asthma.

15-Lipoxygenases regulate the production of chemokines in human lung macrophages

BACKGROUND AND PURPOSE

15-Lipoxygenase (15-LOX) activity is associated with inflammation and immune regulation. The objectives of the present study were to investigate the expression of 15-LOX-1 and 15-LOX-2 and evaluate the enzymes' roles in the polarization of human lung macrophages (LMs) in response to LPS and Th2 cytokines (IL-4/-13).

EXPERIMENTAL APPROACH

LMs were isolated from patients undergoing surgery for carcinoma. The cells were cultured with a 15-LOX inhibitor (PD146176 or ML351), a COX inhibitor (indomethacin), a 5-LOX inhibitor (MK886) or vehicle and then stimulated with LPS (10 ng · mL(-1)), IL-4 (10 ng · mL(-1)) or IL-13 (50 ng · mL(-1)) for 24 h. Levels of ALOX15 (15-LOX-1) and ALOX15B (15-LOX-2) transcripts were determined by real-time quantitative PCR. Immunoassays were used to measure levels of LPS-induced cytokines (TNF-α, CCL2, CCL3, CCL4, CXCL1, CXCL8 and CXCL10) and Th2 cytokine-induced chemokines (CCL13, CCL18 and CCL22) in the culture supernatant.

KEY RESULTS

Stimulation of LMs with LPS was associated with increased expression of ALOX15B, whereas stimulation with IL-4/IL-13 induced the expression of ALOX15. PD146176 and ML351 (10 μM) reduced the release of the chemokines induced by LPS and Th2 cytokines. The effects of these 15-LOX inhibitors were maintained in the presence of indomethacin and MK886. Furthermore, indomethacin revealed the inhibitory effect of PD146176 on TNF-α release.

CONCLUSIONS AND IMPLICATIONS

Inhibition of the 15-LOX pathways is involved in the down-regulation of the in vitro production of chemokines in LMs. Our results suggest that the 15-LOX pathways have a role in the pathogenesis of inflammatory lung disorders and may thus constitute a potential drug target.

Epigenetic regulations of inflammatory cyclooxygenase-derived prostanoids: molecular basis and pathophysiological consequences

The potential relevance of prostanoid signaling in immunity and immunological disorders, or disease susceptibility and individual variations in drug responses, is an important area for investigation. The deregulation of Cyclooxygenase- (COX-) derived prostanoids has been reported in several immunoinflammatory disorders such as asthma, rheumatoid arthritis, cancer, and autoimmune diseases. In addition to the environmental factors and the genetic background to diseases, epigenetic mechanisms involved in the fine regulation of prostanoid biosynthesis and/or receptor signaling appeared to be an additional level of complexity in the understanding of prostanoid biology and crucial in controlling the different components of the COX pathways. Epigenetic alterations targeting inflammatory components of prostanoid biosynthesis and signaling pathways may be important in the process of neoplasia, depending on the tissue microenvironment and target genes. Here, we focused on the epigenetic modifications of inflammatory prostanoids in physiological immune response and immunological disorders. We described how major prostanoids and their receptors can be functionally regulated epigenetically and consequently the impact of these processes in the pathogenesis inflammatory diseases and the development of therapeutic approaches that may have important clinical applications.

Effect of prostaglandin I2 analogs on monocyte chemoattractant protein-1 in human monocyte and macrophage

Chemokines play essential roles during inflammatory responses and in pathogenesis of inflammatory diseases. Monocyte chemotactic protein-1 (MCP-1) is a critical chemokine in the development of atherosclerosis and acute cardiovascular syndromes. MCP-1, by its chemotactic activity, causes diapedesis of monocytes from the lumen to the subendothelial space that leads to atherosclerotic plaque formation. Prostaglandin I2 (PGI2) analogs are used clinically for patients with pulmonary hypertension and have anti-inflammatory effects. However, little is known about the effect of PGI2 analogs on the MCP-1 production in human monocytes and macrophages. We investigated the effects of three conventional (iloprost, beraprost and treprostinil) and one new (ONO-1301) PGI2 analogs, on the expression of MCP-1 expression in human monocytes and macrophages. Human monocyte cell line, THP-1 cell, was treated with PGI2 analogs after LPS stimulation. Supernatants were harvested to measure MCP-1 levels and measured by ELISA. To explore which receptors involved the effects of PGI2 analogs on the expression of MCP-1 expression, IP and EP, PPAR-α and PPAR-γ receptor antagonists were used. Forskolin, a cAMP activator, was used to further confirm the involvement of cAMP on MCP-1 production in human monocytes. Three PGI2 analogs suppressed LPS-induced MCP-1 production in THP-1 cells and THP-1-induced macrophages. Higher concentrations of ONO-1301 also had the suppressive effect. CAY 10449, an IP receptor antagonist, could reverse the effects on MCP-1 production of iloprost on THP-1 cells. Other reported PGI2 receptor antagonists including EP1, EP2, EP4, PPAR-α and PPAR-γ antagonists could not reverse the effect. Forskolin, a cAMP activator, also suppressed MCP-1 production in THP-1 cells. PGI2 analogs suppressed LPS-induced MCP-1 production in human monocytes and macrophages via the IP receptor and cAMP pathway. The new PGI2 analog (ONO-1301) was not better than conventional PGI2 analog in the suppression of MCP-1 production in human monocytes.

Sesamin suppresses macrophage-derived chemokine expression in human monocytes via epigenetic regulation

BACKGROUND

Chemokines play important roles in the pathogenesis of asthmatic inflammation. Sesamin, a class of phytoestrogen isolated from sesame seed Sesamum indicum, is recently regarded as an anti-inflammatory agent. However, the effects of sesamin on asthma-related chemokines are unknown. To this end, we investigated the effects of sesamin on the expression interferon-γ-inducible protein-10 (IP-10/CXCL10), macrophage-derived chemokine (MDC/CCL22), growth-related oncogene-α (GRO-α/CXCL1) and tumor necrosis factor (TNF)-α in human monocytes.

METHODS

Cells were pretreated with sesamin before lipopolysaccharide (LPS) stimulation. IP-10, MDC, GRO-α and TNF-α were measured by ELISA. Involved receptors and intracellular signaling were investigated by receptor antagonists, pathway inhibitors, western blotting and chromatin immunoprecipitation.

RESULTS

Sesamin suppressed LPS-induced MDC in THP-1 and human primary monocytes. Sesamin suppressed LPS-induced IP-10 in THP-1 cells, but not human primary monocytes. Sesamin had no effects on LPS-induced GRO-α and TNF-α expression in THP-1 and human primary monocytes. The suppressive effect of sesamin on MDC was reversed by the estrogen receptor (ER) and peroxisomal proliferator-activated receptor (PPAR)-α antagonists. Sesamin suppressed LPS-induced phosphorylation of mitogen-activated protein kinase (MAPK)-p38 and nuclear factor kappa B (NFκB)-p65. Sesamin suppressed histone H3/H4 acetylation in the MDC promoter region.

CONCLUSION

Sesamin suppressed LPS-induced MDC expression via the ER, the PPAR-α, the MAPK-p38 pathway, the NFκB-p65 pathway and the epigenetic regulation. Sesamin may have therapeutic potential in preventing and treating asthma.

Epigenetic regulation in allergic diseases and related studies

Asthma, a chronic inflammatory disorder of the airway, has features of both heritability as well as environmental influences which can be introduced in utero exposures and modified through aging, and the features may attribute to epigenetic regulation. Epigenetic regulation explains the association between early prenatal maternal smoking and later asthma-related outcomes. Epigenetic marks (DNA methylation, modifications of histone tails or noncoding RNAs) work with other components of the cellular regulatory machinery to control the levels of expressed genes, and several allergy- and asthma-related genes have been found to be susceptible to epigenetic regulation, including genes important to T-effector pathways (IFN-γ, interleukin [IL] 4, IL-13, IL-17) and T-regulatory pathways (FoxP3). Therefore, the mechanism by which epigenetic regulation contributes to allergic diseases is a critical issue. In the past most published experimental work, with few exceptions, has only comprised small observational studies and models in cell systems and animals. However, very recently exciting and elegant experimental studies and novel translational research works were published with new and advanced technologies investigating epigenetic mark on a genomic scale and comprehensive approaches to data analysis. Interestingly, a potential link between exposure to environmental pollutants and the occurrence of allergic diseases is revealed recently, particular in developed and industrialized countries, and endocrine disrupting chemicals (EDCs) as environmental hormone may play a key role. This review addresses the important question of how EDCs (nonylphenol, 4 octylphenol, and phthalates) influences on asthma-related gene expression via epigenetic regulation in immune cells, and how anti-asthmatic agents prohibit expression of inflammatory genes via epigenetic modification. The discovery and validation of epigenetic biomarkers linking exposure to allergic diseases might lead to better epigenotyping of risk, prognosis, treatment prediction, and development of novel therapies.

Phthalates suppress type I interferon in human plasmacytoid dendritic cells via epigenetic regulation

BACKGROUND

Exposure to environmental endocrine-disrupting chemicals (EDCs) is associated with allergy, chronic inflammation, and immunodeficiency. Phthalates, the common EDCs used in plastic industry, may act as adjuvants to disrupt immune system and enhance allergy. Plasmacytoid DCs (pDCs) are predominant cells secreting type I interferon (IFN) against infection and are professional antigen-presenting cells in regulating adaptive immunity. However, the effects of phthalates on the function of pDCs are unknown.

METHODS

Circulating pDCs were isolated from healthy subjects, were pretreated with diethylhexyl phthalate (DEHP) and butyl benzyl phthalate (BBP), and were stimulated with Toll-like receptor (TLR)-9 agonist CpG. IFN-α/IFN-β levels, surface markers, and T-cell stimulatory function were investigated using ELISA, flow cytometry, and pDC/T-cell coculture assay. Mechanisms were investigated using receptor antagonists, pathway inhibitors, Western blotting, and chromatin immunoprecipitation.

RESULTS

Diethylhexyl phthalate and butyl benzyl phthalate suppressed CpG-induced IFN-α/IFN-β expression in pDCs, and the effect was reversed by aryl hydrocarbon receptor (AHR) antagonist. Diethylhexyl phthalate suppressed CpG-activated mitogen-activated protein kinase (MAPK)-MEK1/2-ERK-ELK1 and NFκB signaling pathways. Diethylhexyl phthalate suppressed CpG-induced interferon regulatory factor (IRF)-7 expression by suppressing histone H3K4 trimethylation at IRF7 gene promoter region through inhibiting translocation of H3K4-specific trimethyltransferase WDR5 from cytoplasm into nucleus. Butyl benzyl phthalate or diethylhexyl phthalate-treated pDCs suppressed IFN-γ but enhanced IL-13 production by CD4+ T cells.

CONCLUSION

Phthalates may interfere with immunity against infection and promote the deviation of Th2 response to increase allergy by acting on human pDCs via suppressing IFN-α/IFN-β expression and modulating the ability to stimulate T-cell responses.

Cytokine Gene Expression in CD4 Positive Cells of the Japanese Pufferfish, Takifugu rubripes

CD4⁺ T (Th) cells are a central component of the adaptive immune response and are divided into distinct sets based on their specific cytokine production pattern. Several reports have suggested that fish possess Th subset activity similar to that of mammals. The aim of the present study was to isolate CD4⁺ T cells from the blood of Japanese pufferfish, Fugu rubripes, and to characterize their cytokine expression profile. We produced a specific antibody against Fugu CD4 and performed cell sorting with the magnetic activated cell sorting system. Sorted Fugu CD4⁺ cells were characterized by morphology and expression analysis of cell marker genes. Fugu CD4⁺ cells expressed T-cell marker genes but not macrophage or B-cell marker genes. In addition, peripheral blood lymphocytes were stimulated with lipopolysaccharide (LPS), polycytidylic acid (polyI:C), concanavalin A (ConA) prior to sorting, and then Multiplex RT-PCR was used to examine the expression of Th cytokines by the stimulated Fugu CD4⁺ cells. LPS and polyI:C stimulation upregulated the expression of Th1, Th17 and Treg cytokines and downregulated the expression of Th2 cytokines. ConA stimulation upregulated the expression of all Th cytokines. These results suggest that fish exhibit the same upregulation of Th-specific cytokine expression as in mammals.

Early life exposure to antibiotics and the risk of childhood allergic diseases: an update from the perspective of the hygiene hypothesis

The prevalence of allergic diseases has been growing rapidly in industrial countries during recent decades. It is postulated that growing up with less microbial exposure may render the immune system susceptible to a T helper type 2 (Th2)-predominant allergic response-also known as the hygiene hypothesis. This review delineates recent epidemiological and experimental evidence for the hygiene hypothesis, and integrates this hypothesis into the association between early life exposure to antibiotics and the development of allergic diseases and asthma. Several retrospective or prospective epidemiological studies reveal that early exposure to antibiotics may be positively associated with the development of allergic diseases and asthma. However, the conclusion is inconsistent. Experimental studies show that antibiotics may induce the Th2-skewed response by suppressing the T helper type 1 (Th1) response through inhibition of Th1 cytokines and disruption of the natural course of infection, or by disturbing the microflora of the gastrointestinal (GI) tract and therefore jeopardizing the establishment of oral tolerance and regulatory T cell immune responses. The hygiene hypothesis may not be the only explanation for the rapid increase in the prevalence of allergic diseases and asthma. Further epidemiological and experimental studies addressing the issue of the impact of environmental factors on the development of allergic diseases and the underlying mechanisms may unveil novel strategies for the prevention and treatment of allergic diseases in the future.

Chryseomonas luteola bloodstream infection in a pediatric patient with pulmonary arterial hypertension receiving intravenous treprostinil therapy

Treprostinil is a prostacyclin analogue approved for the treatment of pulmonary arterial hypertension (PAH). It is commonly administered through a central venous catheter (CVC). Treprostinil is associated with the incidence of Gram-negative bacterial bloodstream infections (BSI), a susceptibility that has been associated with a diluent used for treprostinil. We report the case of a 14-year-old boy with idiopathic PAH on continuous intravenous treprostinil therapy who presented with fever and fatigue. A blood culture drawn from his CVC was positive for the rare Gram-negative organism Chryseomonas luteola. The patient made a complete recovery with antibacterial treatment. This is the only documented case of a C. luteola BSI in a PAH patient receiving continuous intravenous treprostinil. We recommend maintaining a high index of suspicion for both common and rare Gram-negative pathogens and the early administration of appropriate antibiotic therapy in this population. The use of an alternate diluent solution, such as Sterile Diluent for Flolan, further decreases the infection risk.

The prostacyclin agonist iloprost aggravates fibrosis and enhances viral replication in enteroviral myocarditis by modulation of ERK signaling and increase of iNOS expression

Enteroviruses, such as coxsackieviruses of group B (CVB), are able to induce a chronic inflammation of the myocardium, which may finally lead to the loss of functional tissue, remodeling processes and the development of fibrosis, thus affecting the proper contractile function of the heart. In other fibrotic diseases like scleroderma, the prostacyclin agonist iloprost was found to inhibit the extracellular signal-regulated kinase (ERK, p44/42 MAPK), a mitogen-activated protein kinase, and consecutively, the expression of the profibrotic cytokine connective tissue growth factor (CTGF), thereby preventing the development of fibrosis. As CTGF was found to mediate fibrosis in chronic CVB3 myocarditis as well, we evaluated whether the in vivo application of iloprost is capable to reduce the development of ERK/CTGF-mediated fibrosis in enteroviral myocarditis. Unexpectedly, the application of iloprost resulted in a prolonged myocardial inflammation and an aggravated fibrosis and failed to reduce activation of ERK and expression of CTGF at later stages of the disease. In addition, viral replication was found to be increased in iloprost-treated mice. Notably, the expression of cardiac inducible nitric oxide synthase (iNOS), which is known to aggravate myocardial damage in CVB3-infected mice, was strongly enhanced by iloprost. Using cultivated bone marrow macrophages (BMM), we confirmed these results, proving that iloprost potentiates the expression of iNOS mRNA and protein in CVB3-infected and IFN-gamma stimulated BMM. In conclusion, these results suggest a critical reflection of the clinical use of iloprost, especially in patients possibly suffering from an enteroviral myocarditis.

PGI2 as a regulator of inflammatory diseases

Prostacyclin, or PGI₂, is an end product derived from the sequential metabolism of arachidonic acid via cyclooxygenase and PGI synthase (PGIS). The receptor for PGI₂, IP, can be found on a variety of cell types and signaling through this receptor exhibits broad physiological effects. Historically, PGI₂ has been understood to play a role in cardiovascular health, specifically having powerful vasodilatory effects via relaxation of smooth muscle and inhibiting of platelet aggregation. For these reasons, PGI₂ has a long history of use for the treatment of pulmonary arterial hypertension (PAH). Only recently, its importance as an immunomodulatory agent has been investigated. PGI₂ regulates both the innate and adaptive immune systems and its effects are, for the most part, thought to be anti-inflammatory or immunosuppressive in nature, which may have implications for its further clinical use.

Immunomodulatory effects of environmental endocrine disrupting chemicals

During recent decades more than 100,000 new chemicals have been introduced as common consumer products into our environment. Among these chemicals, endocrine-disrupting chemicals (EDCs) are of particular concern owing to their toxicity in animal studies and their impacts on human health. EDCs are ubiquitous in the environment, including the air, water, and soil. The endocrine-disrupting effect of EDCs has been found to imitate the action of steroid hormones and promote several endocrine and reproductive disorders in both animal and human studies. In the present review, we focus on the effects of EDCs on the immune system. EDCs interfere with the synthesis of cytokines, immunoglobulins, and inflammatory mediators, and they also affect the activation and survival of immune cells. The dysfunction of the immune system caused by EDCs may lead to the attenuation of immunity (immunodeficiency) against infection or hyperreactivity of immune responses (allergy and autoimmune disease). In this review, we summarize epidemiologic, animal, and cell studies to demonstrate the potential effects of EDCs on immunity, allergy, and autoimmune diseases. We also address the impact of EDCs on epigenetic regulation.

Epigenetics, asthma, and allergic diseases: a review of the latest advancements

Environmental epigenetic regulation in asthma and allergic disease is an exciting area that has gained a great deal of scientific momentum in recent years. Environmental exposures, including prenatal maternal smoking, have been associated with asthma-related outcomes that may be explained by epigenetic regulation. In addition, several known allergy and asthma genes have been found to be susceptible to epigenetic regulation. We review the latest experimental and translational studies that have been published this past year in several areas, including 1) characterization of environmental asthma triggers that induce epigenetic changes, 2) characterization of allergic immune and regulatory pathways important to asthma that undergo epigenetic regulation, 3) evidence of active epigenetic regulation in asthma experimental models and the production of asthma biomarkers, 4) evidence of transmission of an asthma-related phenotype across multiple generations, and 5) "pharmaco-epigenetics." The field has certainly advanced significantly in the past year.

Effect of prostaglandin I2 analogs on cytokine expression in human myeloid dendritic cells via epigenetic regulation

Prostaglandin I(2) (PGI(2)) analog is regarded as a potential candidate for treating asthma. Human myeloid dendritic cells (mDCs) play a critical role in the pathogenesis of asthma. However, the effects of PGI(2) analog on human mDCs are unknown. In the present study, circulating mDCs were isolated from six healthy subjects. The effects of PGI(2) analogs iloprost and treprostinil on cytokine production, maturation and T-cell stimulatory function of human mDCs were investigated. Tumor necrosis factor (TNF)-α and interleukin (IL)-10 were measured by enzyme-linked immunosorbent assay. The expression of costimulatory molecules was investigated by flow cytometry. T-cell stimulatory function was investigated by measuring interferon (IFN)-γ, IL-13 and IL-10 production by T cells cocultured with iloprost-treated mDCs. Intracellular signaling was investigated by Western blot and chromatin immunoprecipitation. We found that iloprost and treprostinil induced IL-10, but suppressed TNF-α production in polyinosinic-polycytidylic acid (poly I:C)-stimulated mDCs. This effect was reversed by the I-prostanoid (IP), E-prostanoid (EP) receptor antagonists or intracellular free calcium (Ca(2+)) chelator. Forskolin, an adenyl cyclase activator, conferred a similar effect. Iloprost and treprostinil increased intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels, and iloprost also increased intracellular Ca(2+). Iloprost suppressed poly I:C-induced mitogen-activated protein kinase (MAPK) phospho-p38 and phospho-activating transcription factor (ATF)2 expression. Iloprost downregulated poly I:C-induced histone H3K4 trimethylation in the TNFA gene promoter region via suppressing translocation of histone 3 lysine 4 (H3K4)-specific methyltransferases MLL (mixed lineage leukemia) and WDR5 (WD repeat domain 5). Iloprost-treated mDCs inhibited IL-13, IFN-γ and IL-10 production by T cells. In conclusion, PGI(2) analogs enhance IL-10 and suppress TNF-α expression through the IP/EP2/EP4 receptors-cAMP and EP1 receptor-Ca(2+) pathway. Iloprost suppressed TNF-α expression via the MAPK-p38-ATF2 pathway and epigenetic regulation by downregulation of histone H3K4 trimethylation.

PGI2 as a regulator of CD4+ subset differentiation and function

Prostaglandin (PG)I(2) has important regulatory functions on the innate and adaptive immune systems. Recent experimental evidence reveals that PGI(2) modulates the development and function of CD4+ T cells subsets, including Th1, Th2, and Th17 cell responses. In vitro and in vivo studies support that PGI(2) generally has an inhibitory effect on Th1 and Th2 activation, differentiation, and cytokine production. In contrast, PGI(2) seems to enhance Th17-favoring polarization conditions, resulting in Th17 cytokine production. Therefore, PGI(2) may either promote or inhibit individual CD4+ cell subsets and impact adaptive immune responses.

Prostaglandin I(2) analogues suppress TNF-α expression in human monocytes via mitogen-activated protein kinase pathway

OBJECTIVE AND DESIGN

Although treatment for asthma control has improved a lot recently, refractory asthma is still a challenge for clinicians. Evidence revealed that anti-tumor necrosis factor (TNF)-α therapy may have potential in treating refractory asthma. Recently in an animal model, prostaglandin I(2) (PGI(2)) analogues can suppress the cardinal feature of asthma. However, whether PGI(2) analogues can regulate TNF-α expression in monocytes and the mechanism is not well-known.

MATERIALS AND METHODS

The human monocytes were pretreated with beraprost, iloprost and treprostinil, three PGI(2) analogues, before stimulation with lipopolysaccharide (LPS). TNF-α concentration of the cell supernatants was measured by ELISA. Intracellular signaling was investigated by Western blot.

RESULTS

PGI(2) analogues suppressed LPS-induced TNF-α expression in THP-1 cells. CAY10449, an I prostanoid receptor antagonist, could reverse these effects. Beraprost increased intracellular cAMP level in THP1 cells. Forskolin, an adenylyl cyclase activator, could confer similar effect. LPS-induced TNF-α expression in THP-1 cells could be reversed by mitogen-activator protein kinase (MAPK)-p38, extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) inhibitors. Western blot revealed that beraprost suppressed MAPK phospho-p38, phosphor-JNK and phosphor-ERK expression.

CONCLUSION

PGI(2) analogues suppressed LPS-induced TNF-α expression in THP-1 cells via the IP receptor-cAMP and the MAPK pathways. PGI(2) analogues may have potentiality to treat asthma.