Myeloid differentiation factor 88-dependent transcriptional regulation of cyclooxygenase-2 expression by CpG DNA: role of NF-kappaB and p38

Zbtb10 transcription factor is crucial for murine cDC1 activation and cytokine secretion

Dendritic cell (DC) activation and cytokine production is tightly regulated. In this study, we found that Zbtb10 expression is activation dependent and it is essential for the immunogenic function of cDC1. Zbtb10 knockdown (KD) significantly reduced the expression of co-stimulatory genes CD80 and CD86 along with cytokines including IL-12, IL-6, and IL-10, in activated cDC1 Mutu-DC line. Consequently, the clonal expansion of CD44⁺ effector T cells in co-cultured CD4⁺ T cells was drastically reduced owing to significantly reduced IL-2. At the same time, these CD44⁺ effector T cells were unable to differentiate toward Tbet⁺ IFNγ⁺ Th1 subtype. Instead, an increased frequency of Th2 cells expressing GATA3⁺ and IL-13⁺ was observed. Interestingly, in Zbtb10 KD condition the co-cultured T cells depicted increased expression of PD1 and LAG3, the T-cell anergic markers. Moreover, the global transcriptome analysis identified that Zbtb10 is pertinent for DC activation and its depletion in cDC1 completely shuts down their immune responses. Mechanistic analysis revealed that Zbtb10 KD enhanced the expression of NKRF (NF-κB repressing factor) leading to drastic suppression of NF-κB related genes. Zbtb10 KD abrogated p65 and RelB nuclear translocation, thereby controlling the activation and maturation of cDC1 and the ensuing adaptive T cell responses.

Increased neutrophil extracellular traps promote metastasis potential of hepatocellular carcinoma via provoking tumorous inflammatory response

BACKGROUND

The propensity of the activated neutrophils to form extracellular traps (NETs) is demonstrated in multiple inflammatory conditions. In this study, we investigated the roles of NETs in metastasis of hepatocellular carcinoma (HCC) and further explored the underlying mechanism of how NETs affect metastasis as well as the therapeutic value.

METHODS

The neutrophils were isolated from the blood of human HCC patients and used to evaluate the formation of NETs. The expression of NET markers was detected in tumor specimens. A LPS-induced NET model was used to investigate the role of NETs on HCC metastasis. RNA-seq was performed to identify the key molecular event triggered by NETs, and their underlying mechanism and therapeutic significance were explored using both in vitro and in vivo assays.

RESULTS

NET formation was enhanced in neutrophils derived from HCC patients, especially those with metastatic HCCs. NETs trapped HCC cells and subsequently induced cell-death resistance and enhanced invasiveness to trigger their metastatic potential, which was mediated by internalization of NETs into trapped HCC cells and activation of Toll-like receptors TLR4/9-COX2 signaling. Inhibition of TLR4/9-COX2 signaling abrogated the NET-aroused metastatic potential. A combination of DNase 1 directly wrecking NETs with anti-inflammation drugs aspirin/hydroxychloroquine effectively reduced HCC metastasis in mice model.

CONCLUSIONS

NETs trigger tumorous inflammatory response and fuel HCC metastasis. Targeting NETs rather than neutrophils themselves can be a practice strategy against HCC metastasis.

Endotracheal intubation results in acute tracheal damage induced by mtDNA/TLR9/NF-κB activity

Tracheitis secondary to placement of an endotracheal tube (ETT) is characterized by neutrophil accumulation in the tracheal lumen, which is generally associated with epithelial damage. Mitochondrial DNA (mtDNA), has been implicated in systemic inflammation and organ dysfunction following trauma; however, less is known about the effects of a foreign body on local trauma and tissue damage. We hypothesized that tracheal damage secondary to the ETT will result in local release of mtDNA at sufficient levels to induce TLR9 and NF‐κB activation. In a swine model we compared the differences between uncoated, and chloroquine (CQ) and N‐acetylcysteine (NAC) coated ETTs as measured by tracheal lavage fluids (TLF) over a period of 6 h. The swine model allowed us to recreate human conditions. ETT presence was characterized by neutrophil activation, necrosis, and release of proinflammatory cytokines mediated by TLR9/NF‐κB induction. Amelioration of the tracheal damage was observed in the CQ and NAC coated ETT group as shown in tracheal tissue specimens and TLF. The role of TLR9/NF‐κB dependent activity was confirmed by HEK‐Blue hTLR9 reporter cell line analysis after coincubation with TLF specimens with predetermined concentrations of NAC or CQ alone or TLR9 inhibitory oligodeoxynucleotide (iODN). These findings indicate that therapeutic interventions aimed at preventing mtDNA/TLR9/NF‐κB activity may have benefits in prevention of acute tracheal damage.

Endotracheal tube-induced sore throat pain and inflammation is coupled to the release of mitochondrial DNA

In the absence of infection, the pathophysiology of endotracheal tube-induced sore throat pain is unclear. Activated neutrophils release elastase, reactive oxygen species, and inflammatory cytokines known to contribute to neuropathic pain. Sterile tissue injury can cause the release of damage-associated molecular patterns such as mitochondrial DNA that promote neutrophil activation. We hypothesized that endotracheal tube-induced sore throat pain is linked to mitochondrial DNA-mediated neutrophil inflammation. A nonrandomized prospective survey for sore throat pain was conducted in 31 patients who required short-term intubation and had no evidence of upper airway infection. Patterns of neutrophil abundance, activation, and mitochondrial DNA levels were analyzed in tracheal lavage fluid following intubation and prior to extubation. Thirteen of 31 patients reported sore throat pain. Sore throat patients had high neutrophilia with elevated adhesion molecule and TLR9 expression and constitutive reactive oxygen species generation. Tracheal lavage fluid from sore throat patients accumulated mitochondrial DNA and stimulated neutrophils to release mediators associated with pain in a TLR9- and DNAse-dependent fashion. Endotracheal tube-induced sore throat is linked to the release of mitochondrial DNA and can drive TLR9-mediated inflammatory responses by neutrophils reported to cause pain. Mitigating the effects of cell-free mitochondrial DNA may prove beneficial for the prevention of endotracheal tube-mediated sore throat pain.

Molecular identification and functional analysis of two variants of myeloid differentiation factor 88 (MyD88) from disk abalone (Haliotis discus discus)

Myeloid differentiation factor 88 (MyD88) is a crucial adaptor protein of the Toll-like receptor (TLR)- and interleukin 1 receptor-mediated signaling pathways and is involved in a diverse array of inflammatory responses via NF-κB activation. In the present study, two MyD88 variants were identified from disk abalone (Haliotis discus discus) and designated AbMyD88-2 and AbMyD88-X. The deduced AbMyD88-2 and AbMyD88-X comprised 433 and 354 amino acids with predicted molecular masses of 48.85 kDa and 40.17 kDa, respectively. AbMyD88-2 and AbMyD88-X possessed typical MyD88 domain structural features including an N-terminal death domain (DD) and C-terminal toll interleukin 1 receptor (TIR) domain similar to those in mammals. Expression analysis of AbMyD88-2 and AbMyD88-X mRNA at different early embryonic developmental stages of abalone by qPCR revealed that their constitutive expression at all developmental stages analyzed with the considerably higher values at the 16-cell (AbMyD88-2) and morula stages (AbMyD88-X). In unchallenged disk abalones, AbMyD88-2 was highly expressed in muscles, while AbMyD88-X mRNA was predominantly transcribed in hemocytes. Moreover, AbMyD88-2 and AbMyD88-X mRNA were differentially modulated in abalone hemocytes after a challenge with live bacteria (Vibrio parahaemolyticus, Listeria monocytogenes), virus (viral hemorrhagic septicemia virus), and pathogen-associated molecular patterns (lipopolysaccharides and Poly I:C). Overexpression of AbMyD88-2 and AbMyD88-X in HEK293T cells induced the activation of the NF-κB promoter. AbMyD88-2 and AbMyD88-X involvement in inflammatory responses was characterized by their overexpression in RAW264.7 murine macrophage cells. These results revealed comparatively higher NO (Nitric oxide) production, induction of inflammatory mediator genes (iNOS and COX2), and proinflammatory genes (IL1β, IL6 and TNFα) expression in abalone MyD88s-overexpressing cells than in mock control in the presence or absence of LPS stimulation. Altogether, these results suggest that existence of a MyD88-dependent like signaling pathway in disk abalone and that both AbMyD88-2 and AbMyD88-X might be involved in innate immune and inflammatory responses.

Group B Streptococci Induce Proinflammatory Responses via a Protein Kinase D1-Dependent Pathway

Group B streptococci (GBS) are one of the leading causes of life-threatening illness in neonates. Proinflammatory responses to GBS mediated through host innate immune receptors play a critical role in the disease manifestation. However, the mechanisms involved in proinflammatory responses against GBS, as well as the contribution of signaling modulators involved in host immune defense, have not been fully elucidated. In the present study, we investigated the role of protein kinase D (PKD)1 in the proinflammatory responses to GBS. We found that both live and antibiotic-killed GBS induce activation of PKD1 through a pathway that is dependent on the TLR signaling adaptor MyD88 and its downstream kinase IL-1R-associated kinase 1, but independent of TNFR-associated factor 6. Our studies using pharmacological PKD inhibitors and PKD1-knockdown macrophages revealed that PKD1 is indispensable for GBS-mediated activation of MAPKs and NF-κB and subsequent expression of proinflammatory mediators. Furthermore, systemic administration of a PKD inhibitor protects d-galactosamine-sensitized mice from shock-mediated death caused by antibiotic-killed GBS. These findings imply that PKD1 plays a critical regulatory role in GBS-induced proinflammatory reactions and sepsis, and inhibition of PKD1 activation together with antibiotic treatment in GBS-infected neonates could be an effective way to control GBS diseases.

Exposure to stimulatory CpG oligonucleotides during gestation induces maternal hypertension and excess vasoconstriction in pregnant rats

Bacterial infections increase risk for pregnancy complications, such as preeclampsia and preterm birth. Unmethylated CpG DNA sequences are present in bacterial DNA and have immunostimulatory effects. Maternal exposure to CpG DNA induces fetal demise and craniofacial malformations; however, the effects of CpG DNA on maternal cardiovascular health have not been examined. We tested the hypothesis that exposure to synthetic CpG oligonucleotides (ODNs) during gestation would increase blood pressure and cause vascular dysfunction in pregnant rats. Pregnant and nonpregnant female rats were treated with CpG ODN (ODN 2395) or saline (Veh) starting on gestational day 14or corresponding day for the nonpregnant groups. Exposure to CpG ODN increased systolic blood pressure in pregnant (Veh: 121 ± 2 mmHg vs. ODN 2395: 134 ± 2 mmHg,P< 0.05) but not in nonpregnant rats (Veh: 111 ± 2 mmHg vs. ODN 2395: 108 ± 5 mmHg,P> 0.05). Mesenteric resistance arteries from pregnant CpG ODN-treated rats had increased contractile responses to U46619 [thromboxane A2(TxA2) mimetic] compared with arteries from vehicle-treated rats [Emax(%KCl), Veh: 87 ± 4 vs. ODN 2395: 104 ± 4,P< 0.05]. Nitric oxide synthase (NOS) inhibition increased contractile responses to U46619, and CpG ODN treatment abolished this effect in arteries from pregnant ODN 2395-treated rats. CpG ODN potentiated the involvement of cyclooxygenase (COX) to U46619-induced contractions. In conclusion, exposure to CpG ODN during gestation induces maternal hypertension, augments resistance artery contraction, increases the involvement of COX-dependent mechanisms and reduces the contribution of NOS-dependent mechanisms to TxA2-induced contractions in mesenteric resistance arteries.

G Protein-coupled Receptor 40 (GPR40) and Peroxisome Proliferator-activated Receptor γ (PPARγ): AN INTEGRATED TWO-RECEPTOR SIGNALING PATHWAY

Peroxisome proliferator-activated receptor γ (PPARγ) ligands have been widely used to treat type 2 diabetes mellitus. However, knowledge of PPARγ signaling remains incomplete. In addition to PPARγ, these drugs also activate G protein-coupled receptor 40 (GPR40), a Gαq-coupled free fatty acid receptor linked to MAPK networks and glucose homeostasis. Notably, p38 MAPK activation has been implicated in PPARγ signaling. Here, rosiglitazone (RGZ) activation of GPR40 and p38 MAPK was found to boost PPARγ-induced gene transcription in human endothelium. Inhibition or knockdown of p38 MAPK or expression of a dominant negative (DN) p38 MAPK mutant blunted RGZ-induced PPARγ DNA binding and reporter activity in EA.hy926 human endothelial cells. GPR40 inhibition or knockdown, or expression of a DN-Gαq mutant likewise blocked activation of both p38 MAPK and PPARγ reporters. Importantly, RGZ induction of PPARγ target genes in primary human pulmonary artery endothelial cells (PAECs) was suppressed by knockdown of either p38 MAPK or GPR40. GPR40/PPARγ signal transduction was dependent on p38 MAPK activation and induction of PPARγ co-activator-1 (PGC1α). Silencing of p38 MAPK or GPR40 abolished the ability of RGZ to induce phosphorylation and expression of PGC1α in PAECs. Knockdown of PGC1α, its essential activator SIRT1, or its binding partner/co-activator EP300 inhibited RGZ induction of PPARγ-regulated genes in PAECs. RGZ/GPR40/p38 MAPK signaling also led to EP300 phosphorylation, an event that enhances PPARγ target gene transcription. Thus, GPR40 and PPARγ can function as an integrated two-receptor signal transduction pathway, a finding with implications for rational drug development.

Circulating mitochondrial DNA and Toll-like receptor 9 are associated with vascular dysfunction in spontaneously hypertensive rats

AIMS

Immune system activation is a common feature of hypertension pathogenesis. However, the mechanisms that initiate this activation are not well understood. Innate immune system recognition and response to danger are becoming apparent in many cardiovascular diseases. Danger signals can arise from not only pathogens, but also damage-associated molecular patterns (DAMPs). Our first hypothesis was that the DAMP, mitochondrial DNA (mtDNA), which is recognized by Toll-like receptor 9 (TLR9), is elevated in the circulation of spontaneously hypertensive rats (SHR), and that the deoxyribonuclease enzymes responsible for its degradation have decreased activity in SHR. Based on these novel SHR phenotypes, we further hypothesized that (i) treatment of SHR with an inhibitory oligodinucleotide for TLR9 (ODN2088) would lower blood pressure and that (ii) treatment of normotensive rats with a TLR9-specific CpG oligonucleotide (ODN2395) would cause endothelial dysfunction and increase blood pressure.

METHODS AND RESULTS

We observed that SHR have elevated circulating mtDNA and diminished deoxyribonuclease I and II activity. Additionally, treatment of SHR with ODN2088 lowered systolic blood pressure. On the other hand, treatment of normotensive rats with ODN2395 increased systolic blood pressure and rendered their arteries less sensitive to acetylcholine-induced relaxation and more sensitive to norepinephrine-induced contraction. This dysfunctional vasoreactivity was due to increased cyclooxygenase and p38 mitogen-activated protein kinase activation, increased reactive oxygen species generation, and reduced nitric oxide bioavailability.

CONCLUSION

Circulating mtDNA and impaired deoxyribonuclease activity may lead to the activation of the innate immune system, via TLR9, and contribute to elevated arterial pressure and vascular dysfunction in SHR.

TLR9 ligands induce S100A8 in macrophages via a STAT3-dependent pathway which requires IL-10 and PGE2

S100A8 and S100A9 are highly-expressed calcium-binding proteins in neutrophils and monocytes, and in subsets of macrophages in inflammatory lesions. Unmethylated CpG motifs found in bacterial and viral DNA are potent activators of innate immunity via Toll-like receptor 9 (TLR9). S100A8, but not S100A9, mRNA and protein was directly induced by CpG-DNA in murine and human macrophages. Induction in murine macrophages peaked at 16 h. CpG-DNA-induced S100A8 required de novo protein synthesis; IL-10 and Prostaglandin E2 (PGE2) synergistically enhanced expression and promoted earlier gene induction. Inhibitors of endogenous IL-10, PGE2, and the E prostanoid (EP) 4 receptor strongly suppressed S100A8 expression, particularly when combined. Thus, S100A8 induction by E. coli DNA required both IL-10 and PGE2/EP4 signaling. The MAPKs, PI3K and JAK pathways were essential, whereas ERK1/2 appeared to play a direct role. S100A8 induction by CpG-DNA was controlled at the transcriptional level. The promoter region responsible for activation, either directly, or indirectly via IL-10 and PGE2, was located within a -178 to -34-bp region and required STAT3 binding. Because of the robust links connecting IL-10 and PGE2 with an anti-inflammatory macrophage phenotype, the induction profile of S100A8 strongly indicates a role for this protein in resolution of inflammation.

Transcription factor Ets-1 inhibits glucose-stimulated insulin secretion of pancreatic β-cells partly through up-regulation of COX-2 gene expression

Increased cyclooxygenase-2 (COX-2) expression is associated with pancreatic β-cell dysfunction. We previously demonstrated that the transcription factor Ets-1 significantly up-regulated COX-2 gene promoter activity. In this report, we used the pancreatic β-cell line INS-1 and isolated rat islets to investigate whether Ets-1 could induce β-cell dysfunction through up-regulating COX-2 gene expression. We investigated the effects of ETS-1 overexpression and the effects of ETS-1 RNA interference on endogenous COX-2 expression in INS-1 cells. We used site-directed mutagenesis and a dual luciferase reporter assay to study putative Ets-1 binding sites in the COX-2 promoter. The effect of ETS-1 1 overexpression on the insulin secretion function of INS-1 cells and rat islets and the potential reversal of these effects by a COX-2 inhibitor were determined in a glucose-stimulated insulin secretion (GSIS) assay. ETS-1 overexpression significantly induces endogenous COX-2 expression, but ETS-1 RNA interference has no effect on basal COX-2 expression in INS-1 cells. Ets-1 protein significantly increases COX-2 promoter activity through the binding site located in the -195/-186 region of the COX-2 promoter. ETS-1 overexpression significantly inhibited the GSIS function of INS-1 cells and islet cells and COX-2 inhibitor treatment partly reversed this effect. These findings indicated that ETS-1 overexpression induces β-cell dysfunction partly through up-regulation of COX-2 gene expression. Moreover, Ets-1, the transcriptional regulator of COX-2 expression, may be a potential target for the prevention of β-cell dysfunction mediated by COX-2.

Interleukin-1 receptor-associated kinase 2- and protein kinase D1-dependent regulation of IRAK-monocyte expression by CpG DNA

As a part of the negative feedback mechanism, CpG DNA induces IRAK-M expression in monocytic cells. In the present study we investigated a biochemical signaling pathway and the transcription factors responsible for CpG DNA-mediated Irak-m gene expression. CpG DNA-induced Irak-m expression did not require new protein synthesis and was regulated at the transcriptional level through an endosomal pH-sensitive TLR9/MyD88 signaling pathway. Over-expression of the dominant negative (DN) form of or gene-specific knockdown of signaling modulators in the TLR9 pathway demonstrated that IRAK4, IRAK1, IRAK2, and PKD1 are required for Irak-m transcription induced by CpG DNA. Over-expression of DN-IRAK1 only partially, but significantly, inhibited CpG DNA-induced Irak-m promoter activity. While IRAK1 was critical for the initial phase, IRAK2 was required for the late phase of TLR9 signaling by sustaining activation of PKD1 that leads to activation of NF-κB and MAPKs. Irak-m promoter-luciferase reporters with alterations in the predicted cis-acting transcriptional regulatory elements revealed that the NF-κB consensus site in the Irak-m promoter region is absolutely required for Irak-m gene expression. AP-1 and CREB binding sites also contributed to the optimal Irak-m expression by CpG DNA. Collectively, our results demonstrate that IRAK2 plays a key role in the TLR9-mediated transcriptional regulation of Irak-m expression by sustaining activation of PKD1 and NF-κB.

Toll-like receptor activation and hypoxia use distinct signaling pathways to stabilize hypoxia-inducible factor 1α (HIF1A) and result in differential HIF1A-dependent gene expression

HIF1A is a transcription factor that plays a central role for the adaptation to tissue hypoxia and for the inflammatory response of myeloid cells, including DCs. HIF1A is stabilized by hypoxia but also by TLR ligands under normoxic conditions. The underlying signaling events leading to the accumulation of HIF1A in the presence of oxygen are still poorly understood. Here, we show that in contrast to hypoxic stabilization of HIF1A, normoxic, TLR-mediated HIF1A accumulation in DCs follows a different pathway that predominantly requires MYD88-dependent NF-κB activity. The TLR-induced HIF1A controls a subset of proinflammatory genes that are insufficiently induced following hypoxia-mediated HIF1A induction. Thus, TLR activation and hypoxia stabilize HIF1A via distinct signaling pathways, resulting in differential HIF1A-dependent gene expression.

Chitin particles induce size-dependent but carbohydrate-independent innate eosinophilia

Murine Mϕ that phagocytose CMP develop into M1; this response depends on the size and the chemical composition of the particles. In contrast, recent studies concluded that chitin particles induce M2 and eosinophil migration, promoting acquired Th2 immune responses against chitin-containing microbes or allergens. This study examined whether these apparently inconsistent responses to chitin could be induced by variation in the size and chemical composition of the chitin particles. We compared the responses of Mϕ with CMP, LCB, and Sephadex G-100 beads (>40 μm). Beads were given i.p. to WT mice and to mice deficient in a CRTH2, a receptor for the eosinophil chemoattractant PGD(2). In contrast to the M1 activation induced by CMP, i.p. administration of LCB or Sephadex beads induced within 24 h a CRTH2-dependent peritoneal eosinophilia, as well as CRTH2-independent activation of peritoneal Mϕ that expressed Arg I, an M2 phenotype. LCB-induced Mϕ exhibited elevated Arg I and a surface MR, reduced surface TLR2 levels, and no change in the levels of CHI3L1 or IL-10 production. Our results indicate that the effects of chitin in vivo are highly dependent on particle size and that large, nonphagocytosable beads, independent of their chemical composition, induce innate eosinophilia and activate Mϕ expressing several M2, but not M1, phenotypes.

Animal products, diseases and drugs: a plea for better integration between agricultural sciences, human nutrition and human pharmacology

Eicosanoids are major players in the pathogenesis of several common diseases, with either overproduction or imbalance (e.g. between thromboxanes and prostacyclins) often leading to worsening of disease symptoms. Both the total rate of eicosanoid production and the balance between eicosanoids with opposite effects are strongly dependent on dietary factors, such as the daily intakes of various eicosanoid precursor fatty acids, and also on the intakes of several antioxidant nutrients including selenium and sulphur amino acids. Even though the underlying biochemical mechanisms have been thoroughly studied for more than 30 years, neither the agricultural sector nor medical practitioners have shown much interest in making practical use of the abundant high-quality research data now available. In this article, we discuss some specific examples of the interactions between diet and drugs in the pathogenesis and therapy of various common diseases. We also discuss, using common pain conditions and cancer as specific examples, how a better integration between agricultural science, nutrition and pharmacology could lead to improved treatment for important diseases (with improved overall therapeutic effect at the same time as negative side effects and therapy costs can be strongly reduced). It is shown how an unnaturally high omega-6/omega-3 fatty acid concentration ratio in meat, offal and eggs (because the omega-6/omega-3 ratio of the animal diet is unnaturally high) directly leads to exacerbation of pain conditions, cardiovascular disease and probably most cancers. It should be technologically easy and fairly inexpensive to produce poultry and pork meat with much more long-chain omega-3 fatty acids and less arachidonic acid than now, at the same time as they could also have a similar selenium concentration as is common in marine fish. The health economic benefits of such products for society as a whole must be expected vastly to outweigh the direct costs for the farming sector.

Mitogen-activated protein kinase signalling and ERK1/2 bistability in asthma

Mitogen-activated protein kinases (MAPKs) integrate signals from numerous receptors and translate these signals into cell functions. MAPKs are critical for immune cell metabolism, migration, production of pro-inflammatory mediators, survival and differentiation. We provide a concise review of the involvement of MAPK in important cells of the immune system. Certain cell functions, e.g. production of pro-inflammatory mediators resolve quickly and may require a transient MAPK activation, other processes such as cell differentiation and long-term survival may require persistent MAPK signal. The persistent MAPK signal is frequently a consequence of positive feedback loops or double negative feedback loops which perpetuate the signal after removal of an external cell stimulus. This self-perpetuated activation of a signalling circuit is a manifestation of its bistability. Bistable systems can exist in 'on' and 'off' states and both states are stable. We have demonstrated the existence of self-perpetuated activation mechanism for ERK1/2 in bronchial epithelial cells. This sustained activation of ERK1/2 supports long-term survival of these cells and primes them for cytokine transcription. ERK1/2 bistability arises from repetitive stimulation of the cell. The repeated stimulation (e.g. repeated viral infection or repeated allergen exposure) seems to be a common theme in asthma and other chronic illnesses. We thus hypothesize that the self-perpetuated ERK1/2 signal plays an important role in the pathogenesis of asthma.

Immunotherapeutic applications of CpG oligodeoxynucleotide TLR9 agonists

Toll-like receptor 9 (TLR9) agonists have demonstrated substantial potential as vaccine adjuvants, and as mono- or combination therapies for the treatment of cancer and infectious and allergic diseases. Commonly referred to as CpG oligodeoxynucleotides (ODN), TLR9 agonists directly induce the activation and maturation of plasmacytoid dendritic cells and enhance differentiation of B cells into antibody-secreting plasma cells. Preclinical and early clinical data support the use of TLR9 agonists as vaccine adjuvants, where they can enhance both the humoral and cellular responses to diverse antigens. In mouse tumor models TLR9 agonists have shown activity not only as monotherapy, but also in combination with multiple other therapies including vaccines, antibodies, cellular therapies, other immunotherapies, antiangiogenic agents, radiotherapy, cryotherapy, and some chemotherapies. Phase I and II clinical trials have indicated that these agents have antitumor activity as single agents and enhance the development of antitumor T-cell responses when used as therapeutic vaccine adjuvants. CpG ODN have shown benefit in multiple rodent and primate models of asthma and other allergic diseases, with encouraging results in some early human clinical trials. Although their potential clinical contributions are enormous, the safety and efficacy of these TLR9 agonists in humans remain to be determined.

RNAi methodologies for the functional study of signaling molecules

RNA interference (RNAi) was investigated with the aim of achieving gene silencing with diverse RNAi platforms that include small interfering RNA (siRNA), short hairpin RNA (shRNA) and antisense oligonucleotides (ASO). Different versions of each system were used to silence the expression of specific subunits of the heterotrimeric signal transducing G-proteins, G alpha i2 and G beta 2, in the RAW 264.7 murine macrophage cell line. The specificity of the different RNA interference (RNAi) platforms was assessed by DNA microarray analysis. Reliable RNAi methodologies against the genes of interest were then developed and applied to functional studies of signaling networks. This study demonstrates a successful knockdown of target genes and shows the potential of RNAi for use in functional studies of signaling molecules.

CpG DNA prevents liver injury and shock-mediated death by modulating expression of interleukin-1 receptor-associated kinases

Tumor necrosis factor-alpha (TNF-alpha) produced by macrophages in response to CpG DNA induces severe liver injury and subsequent death of D-galactosamine (D-GalN)-sensitized mice. In the present study we demonstrate that mice pre-exposed to CpG DNA are resistant to liver injury and death induced by CpG DNA/D-GalN. CpG DNA/D-GalN failed to induce TNF-alpha production and hepatocyte apoptosis in the mice pre-exposed to CpG DNA. In addition, macrophages isolated from the CpG DNA-pretreated mice showed suppressed activation of MAPKs and NF-kappaB and production of TNF-alpha in response to CpG DNA, indicating that the CpG DNA-mediated protection of CpG DNA/D-GalN-challenged mice is due to the hyporesponsiveness of macrophages to CpG DNA. CpG DNA pretreatment in vivo inhibited expression of interleukin-1 receptor-associated kinase (IRAK)-1 while inducing IRAK-M expression in macrophages. Suppressed expression of IRAK-1 was responsible for the macrophage hyporesponsiveness to CpG DNA. However, increased expression of IRAK-M was not sufficient to render macrophages hyporesponsive to CpG DNA but was required for induction of the optimal level of macrophage hyporesponsiveness. Taken together, reduced expression of IRAK-1 and increased expression of IRAK-M after CpG DNA pretreatment resulted in the hyporesponsiveness of macrophages that leads to the protection of mice from hepatic injury and death caused by CpG DNA/D-GalN.

Glutathione suppresses TGF-beta-induced PAI-1 expression by inhibiting p38 and JNK MAPK and the binding of AP-1, SP-1, and Smad to the PAI-1 promoter

Transforming growth factor (TGF)-beta upregulates plasminogen activator inhibitor type 1 (PAI-1) in a variety of cell types, and PAI-1 is considered to be an essential factor for the development of fibrosis. Our previous studies demonstrated that TGF-beta decreased intracellular glutathione (GSH) content in murine embryonic fibroblasts (NIH/3T3 cells), whereas treatment of the cells with GSH, which restored intracellular GSH concentration, inhibited TGF-beta-induced collagen accumulation by blocking PAI-1 expression and enhancing collagen degradation. In the present study, we demonstrate that GSH blocks TGF-beta-induced PAI-1 promoter activity in NIH/3T3 cells, which is associated with an inhibition of TGF-beta-induced JNK and p38 phosphorylation. Interestingly, although exogenous GSH does not affect phosphorylation and/or nuclear translocation of Smad2/3 and Smad4, it completely eliminates TGF-beta-induced binding of transcription factors to not only AP-1 and SP-1 but also Smad cis elements in the PAI-1 promoter. Decoy oligonucleotides (ODN) studies further demonstrate that AP-1, SP-1, and Smad ODNs abrogate the inhibitory effect of GSH on TGF-beta-induced PAI-1 promoter activity and inhibit TGF-beta-induced expression of endogenous PAI-1. Furthermore, we show that GSH reduces TGF-beta-stimulated reactive oxygen species (ROS) signal. Blocking ROS production with diphenyleneiodonium or scavenging ROS with a superoxide dismutase and catalase mimetic MnTBaP dramatically reduces TGF-beta-induced p38 and JNK phosphorylation as well as PAI-1 gene expression. In composite, these findings suggest that GSH inhibits TGF-beta-stimulated PAI-1 expression in fibroblasts by blocking the JNK/p38 pathway, probably by reducing ROS, which leads to an inhibition of the binding of transcription factors to the AP-1, SP-1, and Smad cis elements in the PAI-1 promoter.

Molecular signaling in necrotizing enterocolitis: regulation of intestinal COX-2 expression

Necrotizing enterocolitis (NEC) is the most common surgical emergency in premature infants. The underlying etiology of NEC remains unknown, although bacterial colonization of the gut, formula feeding, and perinatal stress have been implicated as putative risk factors. The disease is characterized by exuberant gut inflammation leading to ischemia and coagulation necrosis of the intestinal epithelium. The molecular and cellular mechanisms responsible for these pathologic changes are poorly understood. It has been shown that various exogenous and endogenous mediators such as lipopolysaccharide, inflammatory cytokines, platelet activating factor, and nitric oxide may play a role in the pathogenesis of NEC. Recent studies in our laboratory and others have established a link between NEC and activation of cyclooxygenase-2, the enzyme that catalyzes the rate-limiting step in the biosynthesis of prostanoids. The challenge is in defining the molecular signaling pathways leading to accumulation of these mediators early in the disease progression, before the onset of tissue necrosis and systemic sepsis. Identification and characterization of these pathways could lead to the development of novel treatment strategies to alleviate the morbidity and mortality associated with NEC.

Several transcription factors regulate COX-2 gene expression in pancreatic beta-cells

Cyclooxygenase-2 (COX-2) expression is associated with many aspects of physiological and pathological conditions, including pancreatic beta-cell dysfunction. Prostaglandin E2 (PGE2) production, as a consequence of COX-2 gene induction, has been reported to impair beta-cell function. The molecular mechanisms involved in the regulation of COX-2 gene expression are not fully understood. In this report, we used pancreatic beta-cells (RINm5F) to explore the potential transcription factors regulating COX-2 promoter activity. Using promoter screening method, we selected several transcription factors in our study. Through luciferase reporter studies, we found that these factors can regulate COX-2 promoter activity in RINm5F cells. Among these factors, cyclic AMP response-element binding protein (CREB), Ets family members Ets-1 and Elk-1 can positively regulate COX-2 promoter activity. On the contrary, signal transducer and activator of transcription 1 (STAT1) plays a negative role on COX-2 promoter. Our findings will be helpful for better understanding the transcriptional regulation of COX-2 in pancreatic beta-cells. Moreover, these transcriptional regulators of COX-2 expression will be potential targets for the prevention of beta-cell damage mediated by PGE2.

Cyclooxygenase-2 Inhibition Attenuates Antibody Responses against Human Papillomavirus-Like Particles

Vaccination to generate protective humoral immunity against infectious disease is becoming increasingly important due to emerging strains of virus, poorly immunogenic vaccines, and the threat of bioterrorism. We demonstrate that cyclooxygenase-2 (Cox-2) is crucial for optimal Ab responses to a model vaccine, human papillomavirus type 16 virus-like particles (HPV 16 VLPs). Cox-2-deficient mice produce 70% less IgG, 50% fewer Ab-secreting cells, and 10-fold less neutralizing Ab to HPV 16 VLP vaccination compared with wild-type mice. The reduction in Ab production by Cox-2(-/-) mice was partially due to a decrease in class switching. SC-58125, a structural analog of the Cox-2-selective inhibitor Celebrex reduced by approximately 70% human memory B cell differentiation to HPV 16 VLP IgG-secreting cells. The widespread use of nonsteroidal anti-inflammatory drugs and Cox-2-selective inhibitory drugs may therefore reduce vaccine efficacy, especially when vaccines are poorly immunogenic or the target population is poorly responsive to immunization.

Enhancement of infectious disease vaccines through TLR9-dependent recognition of CpG DNA

The adaptive immune system-with its remarkable ability to generate antigen-specific antibodies and T lymphocytes against pathogens never before "seen" by an organism-is one of the marvels of evolution. However, to generate these responses, the adaptive immune system requires activation by the innate immune system. Toll-like receptors (TLRs) are perhaps the best-understood family of innate immune receptors for detecting infections and stimulating adaptive immune responses. TLR9 appears to have evolved to recognize infections by a subtle structural difference between eukaryotic and prokaryotic/viral DNA; only the former frequently methylates CpG dinucleotides. Used as vaccine adjuvants, synthetic oligodeoxynucleotide (ODN) ligands for TLR9--CpG ODN--greatly enhance the speed and strength of the immune responses to vaccination.

TLR9 in health and disease

Toll-like receptor 9 (TLR9) is specialized for the recognition of pathogenic nucleic acids. TLR9 is expressed in intracellular compartments where it responds specifically to pathogen DNA. Several factors contribute to the ability of TLR9 to discriminate between self and foreign DNA. Regulatory mechanisms of the innate and adaptive immune system exist that balance the immune responses mediated by TLR9. Short synthetic CpG oligodeoxynucleotides are used to induce controlled and directed TLR9-dependent stimulation and are effective immune modulators in preclinical and clinical studies. This review will summarize the interplay between TLR9-dependent opposing stimulatory and regulatory effects in innate and adaptive immunity.

Therapeutic potential of Toll-like receptor 9 activation

In the decade since the discovery that mouse B cells respond to certain unmethylated CpG dinucleotides in bacterial DNA, a specific receptor for these 'CpG motifs' has been identified, Toll-like receptor 9 (TLR9), and a new approach to immunotherapy has moved into the clinic based on the use of synthetic oligodeoxynucleotides (ODN) as TLR9 agonists. This review highlights the current understanding of the mechanism of action of these CpG ODN, and provides an overview of the preclinical data and early human clinical trial results using these drugs to improve vaccines and treat cancer, infectious disease and allergy/asthma.

Phagocytosis of N-acetyl-D-glucosamine particles, a Th1 adjuvant, by RAW 264.7 cells results in MAPK activation and TNF-alpha, but not IL-10, production

A practical and highly effective Th1 adjuvant should induce Th1 cytokines (IL-12, IL-18, and TNF-alpha) but not the Th2 cytokine IL-10, an inhibitor of Th1 responses. In this study, phagocytosis of N-acetyl-d-glucosamine polymer (chitin) particles by RAW 264.7 cells, a murine macrophage-like cell line, resulted in phosphorylation of MAPK (p38, Erk 1/2, and JNK), and production of relatively high levels of TNF-alpha and COX-2 with increased PGE(2) release. Similar results were observed in response to oligonucleotides with CpG motifs, mycobacterial components and endotoxin. However, these bacterial components also induced a large amount of IL-10. Chitin particles, in contrast, failed to induce detectable levels of IL-10, although the production of high levels of PGE(2) and TNF-alpha and the activation of MAPK's are potentially positive signals for IL-10 production. Thus, our results indicate that chitin particles act as a unique Th1 adjuvant for macrophages without inducing increased production of IL-10.

Nitric oxide activation of Erk1/2 regulates the stability and translation of mRNA transcripts containing CU-rich elements

Nitric oxide (NO*) can stabilize mRNA by activating p38 mitogen-activated protein kinase (MAPK). Here, transcript stabilization by NO* was investigated in human THP-1 cells using microarrays. After LPS pre-stimulation, cells were treated with actinomycin D and then exposed to NO* without or with the p38 MAPK inhibitor SB202190 (SB). The decay of 220 mRNAs was affected; most were stabilized by NO*. Unexpectedly, SB often enhanced rather than antagonized transcript stability. NO* activated p38 MAPK and Erk1/2; SB blocked p38 MAPK, but further activated Erk1/2. RT-PCR confirmed that NO* and SB could additively stabilize certain mRNA transcripts, an effect abolished by Erk1/2 inhibition. In affected genes, these responses were associated with CU-rich elements (CURE) in 3'-untranslated regions (3'-UTR). NO* stabilized the mRNA of a CURE-containing reporter gene, while repressing translation. Dominant-negative Mek1, an Erk1/2 inhibitor, abolished this effect. NO* similarly stabilized, but blocked translation of MAP3K7IP2, a natural CURE-containing gene. NO* increased hnRNP translocation to the cytoplasm and binding to CURE. Over-expression of hnRNP K, like NO*, repressed translation of CURE-containing mRNA. These findings define a sequence-specific mechanism of NO*-triggered gene regulation that stabilizes mRNA, but represses translation.

Nonclassical pathway of Pseudomonas aeruginosa DNA-induced interleukin-8 secretion in cystic fibrosis airway epithelial cells

Pseudomonas aeruginosa is a critical colonizer of the respiratory tract in cystic fibrosis. The chronic infections with this microorganism contribute to excessive inflammation and progressive lung damage in cystic fibrosis patients. The full repertoire of Pseudomonas products that promote inflammation in the cystic fibrosis lung is not known. Here we show that P. aeruginosa DNA released from the bacterium, but not human DNA from epithelial cells or Escherichia coli DNA, displays proinflammatory properties and induces human respiratory epithelial cells to secrete interleukin-8 (IL-8), a key chemokine causing excessive neutrophil infiltration in the cystic fibrosis lung. IL-8 secretion was not due to an increase in NF-kappaB- or activator protein-1-dependent IL-8 promoter transcription, but instead depended on p38 and Erk mitogen-activated protein kinases. No secretion of IL-8 was observed using conventional Toll-like receptor 9 ligands (CpG oligonucleotides), although it could be demonstrated that parts of the Toll-like receptor 9-signaling pathway were functional, since class B and C CpG oligonucleotide ligands stimulated production of RANTES chemokine. The IL-8 secretion in response to P. aeruginosa DNA was decreased by treatments that inhibit acidification of intracellular organelles, using chloroquine, a pH-neutralizing compound, or bafilomycin A1, an inhibitor of vacuolar H+-ATPase. These data indicate that DNA released from P. aeruginosa during chronic infections may significantly contribute to the proinflammatory processes in cystic fibrosis. Our findings also show that treatments with drugs diminishing organellar acidification may reduce the inflammatory response in cystic fibrosis.

Increased expression of cyclooxygenase-2 mediates enhanced contraction to endothelin ETA receptor stimulation in endothelial nitric oxide synthase knockout mice

The aim of this study was to determine whether prolonged loss of NO activity, in endothelial NO synthase knockout (eNOS(-/-)) mice, influences endothelin (ET) ETA receptor-mediated smooth muscle contraction and, if so, to define the underlying mechanism(s). In isolated endothelium-denuded abdominal aortas, contractions to the selective ETA receptor agonist ET-1(1-31) were significantly increased in aortas from eNOS(-/-) compared with wild-type (WT) mice. In contrast, contractions to the alpha1-adrenergic agonist phenylephrine or the thromboxane (TX) A2 analog U-46619 were similar between eNOS(-/-) and WT mice. Immunofluorescent and Western blot analysis demonstrated that the aortic expression of ETA receptors was decreased in eNOS(-/-) compared with WT mice. Contractions evoked by ET-1(1-31), but not phenylephrine, were reduced by inhibition of cyclooxygenase-2 (COX-2) (indomethacin or celecoxib) or of TXA2/prostaglandin H2 receptors (SQ-29548). After COX inhibition, contractions to ET-1(1-31) were no longer increased and were actually decreased in eNOS(-/-) compared with WT aortas. Western blot analysis revealed that endothelium-denuded abdominal aortas express COX-2, but not COX-1, and that expression of COX-2 was significantly increased in eNOS(-/-) compared with WT mice. Contractions to the COX substrate arachidonic acid were also increased in eNOS(-/-) aortas. Furthermore, ET-1(1-31) but not phenylephrine stimulated production of the TXA2 metabolite TXB2, which was increased in eNOS(-/-) compared with WT aortas. Therefore, COX-2 plays a crucial and selective role in ETA-mediated smooth muscle contraction. Furthermore, COX-2 expression is increased in eNOS(-/-) mice, which overcomes a reduced expression of ETA receptors and enables a selective increase in contraction to ETA receptor stimulation.

CCAAT/enhancer-binding protein mediates carbon monoxide-induced suppression of cyclooxygenase-2

Cyclooxygenase-2 (COX-2) is a key enzyme involved in the inflammatory process that is rapidly induced in macrophages in response to LPS. Carbon monoxide (CO), a byproduct of heme oxygnease-1, can suppress proinflammatory response in various in vitro and in vivo models of inflammation. This study was undertaken to examine whether CO can regulate (and if so, to delineate the mechanism by which CO regulates) LPS-induced COX-2 expression in macrophages. RAW 264.7 murine macrophages were stimulated with LPS (0-10 ng/ml) with or without CO (500 ppm). Northern and Western blot analysis was done. Progstaglandin E(2) and nitrite concentration was measured from cell culture supernatant. Electrophoretic mobility shift assay was performed to assess nuclear factor binding. CO downregulated LPS-induced COX-2 mRNA and protein expression. CO also inhibited LPS-induced prostaglandin E(2) secretion (P < 0.05). CO also decreased LPS-induced CCAAT/enhancer-binding protein (C/EBP) beta and delta protein expression in LPS-treated RAW 264.7 cells. Gel shift analysis revealed that CO treatment decreased LPS-induced activation of protein binding to C/EBP consensus oligonucleotides of murine cyclooxygenase-2 promoter. CO also decreased LPS-induced nitric oxide synthase-2 protein expression and nitrite production, and decreased LPS-induced activation of protein binding to C/EBP consensus oligonucleotides of murine nitric oxide synthase-2 promoter. CO may act as an important regulator of inflammation by virtue of its ability to regulate C/EBPs.

Synergistic activation of macrophages via CD40 and TLR9 results in T cell independent antitumor effects

We have previously shown that macrophages (Mphi) can be activated by CD40 ligation to become cytotoxic against tumor cells in vitro. Here we show that treatment of mice with agonistic anti-CD40 mAb (anti-CD40) induced up-regulation of intracellular TLR9 in Mphi and primed them to respond to CpG-containing oligodeoxynucleotides (CpG), resulting in synergistic activation. The synergy between anti-CD40 and CpG was evidenced by increased production of IFN-gamma, IL-12, TNF-alpha, and NO by Mphi, as well as by augmented apoptogenic effects of Mphi against tumor cells in vitro. The activation of cytotoxic Mphi after anti-CD40 plus CpG treatment was dependent on IFN-gamma but not TNF-alpha or NO, and did not require T cells and NK cells. Anti-CD40 and CpG also synergized in vivo in retardation of tumor growth in both immunocompetent and immunodeficient mice. Inactivation of Mphi in SCID/beige mice by silica treatment abrogated the antitumor effect. Taken together, our results show that Mphi can be activated via CD40/TLR9 ligation to kill tumor cells in vitro and inhibit tumor growth in vivo even in immunocompromised tumor-bearing hosts, indicating that this Mphi-based immunotherapeutic strategy may be appropriate for clinical testing.

Lipopolysaccharide induces cyclooxygenase-2 in intestinal epithelium via a noncanonical p38 MAPK pathway

Necrotizing enterocolitis (NEC), a severe intestinal inflammation in neonates, occurs following bacterial colonization of the gut. LPS-induced production of inflammatory factors in immature enterocytes may be a factor in NEC. Previously, we described LPS-induced p38 MAPK-dependent expression of cyclooxygenase-2 (COX-2) in rat IEC-6 cells. In this study, we examine COX-2 expression in newborn rat intestinal epithelium and further characterize the mechanisms of COX-2 regulation in enterocytes. Induction of NEC by formula feeding/hypoxia increased phospho-p38 and COX-2 levels in the intestinal mucosa. Celecoxib, a selective COX-2 inhibitor, exacerbated the disease, suggesting a protective role for COX-2. COX-2 was induced in the intestinal epithelium by LPS in vivo and ex vivo. The latter response was attenuated by the p38 inhibitor SB202190, but not by inhibitors of ERK, JNK, or NF-kappaB. In IEC-6 enterocytes, COX-2 was induced by the expression of MAPK kinase 3 EE (MKK3EE), a constitutive activator of p38, but not of activators of ERK or JNK pathways. However, neither MKK3/6 nor MKK4, the known p38 upstream kinases, were activated by LPS. Dominant-negative MKK3 or MKK4 or SB202190 failed to prevent LPS-induced, p38-activating phosphorylation, ruling out important roles of these kinases or p38 autophosphorylation. LPS increased COX-2 and activating phosphorylation of p38 with similar dose-response. Blockade of LPS-induced expression of COX-2-luciferase reporter and destabilization of COX-2 message by SB202190 indicate that p38 regulates COX-2 at transcription and mRNA stability levels. Our data indicate that p38-mediated expression of COX-2 proceeds through a novel upstream pathway and support the role of the neonate's enterocytes as bacterial sensors.

Dual inhibitory effects of furonaphthoquinone compound on enzyme activity and lipopolysaccharide-induced expression of cyclooxygenase-2 in macrophages

2-Methyl-2-(2-methylpropenyl)-2,3-dihydronaphtho[2,3-b]furan-4,9-dione (NFD-37) is a synthetic furonaphthoquinone compound. In the present study, the NFD-37 compound was found to inhibit prostaglandin (PG) E(2) production in lipopolysaccharide (LPS)-stimulated macrophages RAW 264.7. NFD-37 compound exhibited a preferred inhibition on enzyme activity of cyclooxygenase (COX)-2 over COX-1. Further, NFD-37 compound attenuated LPS-induced synthesis of both mRNA and protein of COX-2, and suppressed LPS-induced COX-2 promoter activity in the macrophages, indicating that the furonaphthoquinone compound could down-regulate LPS-induced COX-2 expression at the transcription level. Even though COX-2 promoter behaves as a sophisticated biosensor for host defense, nuclear factor (NF)-kappaB activation has been evidenced to play a major mechanism for LPS-induced COX-2 expression in macrophages. NFD-37 compound exhibited a dose-dependent inhibitory effect on LPS-induced phosphorylation of inhibitory kappaBalpha (IkappaBalpha) protein, and subsequently inhibited IkappaBalpha degradation, DNA binding activity of NF-kappaB complex as well as NF-kappaB transcriptional activity in macrophages RAW 264.7. In another experiment, NFD-37 compound inhibited both COX-2 promoter activity and GST-IkappaBalpha phosphorylation elicited by an expression vector encoding IkappaB kinase beta. Taken together, NFD-37 compound inhibited enzyme activity of COX-2 but also suppressed COX-2 expression depending on NF-kappaB activation, and thus could provide an invaluable tool to investigate pharmacological potential in the excess PG-related disorders.

The Ets transcription factor ESE-1 mediates induction of the COX-2 gene by LPS in monocytes

Cyclooxygenase-2 (COX-2) is a key enzyme in the production of prostaglandins that are major inflammatory agents. COX-2 production is triggered by exposure to various cytokines and to bacterial endotoxins. We present here a novel role for the Ets transcription factor ESE-1 in regulating the COX-2 gene in response to endotoxin and other pro-inflammatory stimuli. We report that the induction of COX-2 expression by lipopolysaccharide (LPS) and pro-inflammatory cytokines correlates with ESE-1 induction in monocyte/macrophages. ESE-1, in turn, binds to several E26 transformation specific (Ets) sites on the COX-2 promoter. In vitro analysis demonstrates that ESE-1 binds to and activates the COX-2 promoter to levels comparable to LPS-mediated induction. Moreover, we provide results showing that the induction of COX-2 by LPS may require ESE-1, as the mutation of the Ets sites in the COX-2 promoter or overexpression of a dominant-negative form of ESE-1 inhibits LPS-mediated COX-2 induction. The effect of ESE-1 on the COX-2 promoter is further enhanced by cooperation with other transcription factors such as nuclear factor-kappa B and nuclear factor of activated T cells. Neutralization of COX-2 is the goal of many anti-inflammatory drugs. As an activator of COX-2 induction, ESE-1 may become a target for such therapeutics as well. Together with our previous reports of the role of ESE-1 as an inducer of nitric oxide synthase in endothelial cells and as a mediator of pro-inflammatory cytokines in vascular and connective tissue cells, these results establish ESE-1 as an important player in the regulation of inflammation.

Nanoparticle based systemic gene therapy for lung cancer: molecular mechanisms and strategies to suppress nanoparticle-mediated inflammatory response

Cancer gene therapy for the treatment of lung cancer has shown promise in the laboratory and in Phase I/II clinical trials. However, it is currently limited to treating localized tumors due to host-immunity against the gene delivery vector and the transgene. Therefore, there is a tremendous effort to develop and test alternate gene delivery vectors that are efficient, non-immunogenic, and applicable for systemic therapy. One such gene delivery vehicle is the non-viral vector, DOTAP:cholesterol (DOTAP:Chol) nanoparticle. Preclinical studies from our laboratory has shown that DOTAP:Chol. nanoparticles are effective systemic gene delivery vectors that efficiently deliver tumor-suppressor genes to disseminated lung tumors. Based on our findings we have recently initiated a Phase-I trial for systemic treatment of lung cancer using a novel tumor suppressor gene, FUS1. Although DOTAP:Chol. nanoparticles complexed to DNA (DNA-nanoparticles) are efficient vectors for systemic therapy, induction of an inflammatory response in a dose-dependent fashion has also been observed thereby limiting its use. A better understanding of the underlying mechanism for DNA-nanoparticles-mediated inflammatory response will allow us to develop strategies to suppress inflammation and expand the therapeutic window in treating human cancer. In the present study we conducted experiments examining the mechanism of nanoparticle-mediated inflammatory response in vitro and in vivo. We demonstrate that systemic administration of DNA-nanoparticles induced multiple signaling molecules both in vitro and in vivo that are associated with inflammation. Use of small molecule inhibitors against the signaling molecules resulted in their suppression and thereby reduced inflammation without affecting transgene expression. Our results provide a rationale to use small molecule inhibitors to suppress nanoparticle-mediated inflammation when administered systemically. Further development and testing will allow us to incorporate this strategy into future clinical trials that is based on systemic non-viral vector gene therapy.

Toll-like receptor 9 is expressed on follicle-associated epithelia containing M cells in swine Peyer's patches

The precise distribution and expression of Toll-like receptor (TLR) 9 in gut-associated lymphoid tissues (GALTs) has not been elucidated. In this study, we investigated the expression pattern of TLR9 in adult and neonatal swine GALTs by real-time quantitative PCR, western blot, confocal laser microscopy and flow cytometric analysis. The swine TLR9 gene was preferentially expressed in adult Peyer's patches (Pps) and mesenteric lymph nodes (MLNs), which contained approximately three times higher TLR9 than the spleen. Other tissues exhibited only weak expression of TLR9. In neonatal swine, elevated expression of TLR9 was detected only in MLNs. We firstly showed that highly expressive (TLR9(+)) cells were formed in Pps and MLNs. In addition, TLR9(+) cells were present not only in immune cells such as dendritic cells and B cells but also in follicle-associated epithelia (FAE) including membranous cells (M cells) in Pps. These results suggest that Pps and MLNs provide the host defense with the ability to respond to a variety of bioactive oligonucleotides (ODNs) from bacteria at a conductive site of initial immune responses.

Dexamethasone-induced and estradiol-induced CREB activation and annexin 1 expression in CCRF-CEM lymphoblastic cells: evidence for the involvement of cAMP and p38 MAPK

AIMS

Annexin 1 (ANXA1), a member of the annexin family of calcium-binding and phospholipid-binding proteins, is a key mediator of the anti-inflammatory actions of steroid hormones. We have previously demonstrated that, in the human lymphoblastic CCRF-CEM cell line, both the synthetic glucocorticoid hormone, dexamethasone (Dex), and the estrogen hormone, 17beta-estradiol (E2beta), induce the synthesis of ANXA1, by a mechanism independent of the activation of their nuclear receptors. Recently, it was reported that the gene coding for ANXA1 contains acAMP-responsive element (CRE). In this work, we investigated whether Dex and E2beta were able to induce the activation of CRE binding proteins (CREB) in the CCRF-CEM cells. Moreover, we studied the intracellular signalling pathways involved in CREB activation and ANXA1 synthesis in response to Dex and E2beta; namely, the role of cAMP and the p38 mitogen activated protein kinase (MAPK).

RESULTS

The results show that Dex and E2beta were as effective as the cAMP analogue, dBcAMP, in inducing CREB activation. On the contrary, dBcAMP induced ANXA1 synthesis as effectively as these steroid hormones. Furthermore, the cAMP antagonist, Rp-8-Br-cAMPS, and the specific p38 MAPK inhibitor,SB203580, effectively prevented both Dex-induced, E2beta-induced and dBcAMP-induced CREB activation and ANXA1 synthesis.

CONCLUSIONS

Taken together, our results suggest that,in CCRF-CEM cells, Dex-induced and E2beta-inducedANXA1 expression requires the activation of the transcription factor CREB, which in turn seems to be mediated by cAMP and the p38 MAPK. These findings also suggest that, besides the nuclear steroid hormone receptors, other transcription factors, namely CREB, may play important roles in mediating the anti-inflammatory actions of glucocorticoids and oestrogen hormones.

Endoplasmic reticulum stress stimulates the expression of cyclooxygenase-2 through activation of NF-kappaB and pp38 mitogen-activated protein kinase

Expression of mutant proteins or viral infection may interfere with proper protein folding activity in the endoplasmic reticulum (ER). Several pathways that maintain cellular homeostasis were activated in response to these ER disturbances. Here we investigated which of these ER stress-activated pathways induce COX-2 and potentially oncogenesis. Tunicamycin and brefeldin A, two ER stress inducers, increased the expression of COX-2 in ML-1 or MCF-7 cells. Nuclear translocation of NF-kappaB and activation of pp38 MAPK were observed during ER stress. IkappaBalpha kinase inhibitor Bay 11-7082 or IkappaBalpha kinase dominant negative mutant significantly inhibited the induction of COX-2. pp38 MAPK inhibitor SB203580 or eIF2alpha phosphorylation inhibitor 2-aminopurine attenuated the nuclear NF-kappaB DNA binding activity and COX-2 induction. Expression of mutant hepatitis B virus (HBV) large surface proteins, inducers of ER stress, enhanced the expression of COX-2 in ML-1 and HuH-7 cells. Transgenic mice showed higher expression of COX-2 protein in liver and kidney tissue expressing mutant HBV large surface protein in vivo. Similarly, increased expression of COX-2 mRNA was observed in human hepatocellular carcinoma tissue expressing mutant HBV large surface proteins. In ML-1 cells expressing mutant HBV large surface protein, anchorage-independent growth was enhanced, and the enhancement was abolished by the addition of specific COX-2 inhibitors. Thus, ER stress due either to expression of viral surface proteins or drugs can stimulate the expression of COX-2 through the NF-kappaB and pp38 kinase pathways. Our results provide important insights into cellular carcinogenesis associated with latent endoplasmic reticulum stress.

Influence of Coinfecting Pathogens on HIV Expression: Evidence for a Role of Toll-Like Receptors

Immune activation of HIV gene expression as a consequence of the host response to coinfecting pathogens has been implicated as an important factor in AIDS progression. Immune responsiveness to many of the infectious agents associated with HIV has been demonstrated to depend on a family of innate recognition molecules, known as Toll-like receptors (TLR). Therefore, TLR-pathogen interactions could play an indirect role in regulating HIV-associated disease. In this review, we summarize emerging evidence for the influence of TLR recognition on HIV gene activation and AIDS progression.

Myeloid differentiation factor 88-dependent post-transcriptional regulation of cyclooxygenase-2 expression by CpG DNA: tumor necrosis factor-alpha receptor-associated factor 6, a diverging point in the Toll-like receptor 9-signaling

The immune stimulatory unmethylated CpG motifs present in bacterial DNA (CpG DNA) induce expression of cyclooxygenase-2 (cox-2). The present study demonstrates that CpG DNA can up-regulate cox-2 expression by post-transcriptional mechanisms in RAW264.7 cells. To determine the CpG DNA-mediated signaling pathway that post-transcriptionally regulates cox-2 expression, a cox-2 translational reporter (COX2-3'-UTR-luciferase) was generated by inserting sequences within the 3'-untranslated region (UTR) of cox-2 to the 3' end of the luciferase gene under control of the SV40 promoter. CpG DNA-induced COX2-3'-UTR-luciferase activity was completely inhibited by an endosomal acidification inhibitor chloroquine, a Toll-like receptor 9 antagonist inhibitory CpG DNA, or overexpression of a dominant negative (DN) form of MyD88. However, overexpression of DN-IRAK-1 or DN-TRAF6 resulted in substantial, but not complete, inhibition of the CpG DNA-induced COX2-3'-UTR-luciferase activity. Activation of all three MAPKs (ERK, p38, and JNK) was required for optimal COX2-3'-UTR-luciferase activity induced by CpG DNA. Overexpression of DN-TRAF6 suppressed CpG DNA-mediated activation of p38 and JNK, but not ERK, explaining the partial inhibitory effects of DN-TRAF6 on CpG DNA-induced COX2-3'-UTR-luciferase activity. Co-expression of DN-TRAF6 and N17Ras completely inhibited CpG DNA-induced COX2-3'-UTR-luciferase activity, indicating the involvement of Ras in CpG DNA-mediated ERK and COX2-3'-UTR regulation. Collectively, our results suggest that MyD88 and MAPKs play a key regulatory role in CpG DNA-mediated cox-2 expression at the post-transcriptional level and that TRAF6 is a diverging point in the Toll-like receptor 9-signaling pathway for CpG DNA-mediated MAPK activation.