Activation of the human RANTES gene promoter in a macrophage cell line by lipopolysaccharide is dependent on stress-activated protein kinases and the IkappaB kinase cascade: implications for exacerbation of allergic inflammation by environmental pollutants

Neuregulin-1 elicits a regulatory immune response following traumatic spinal cord injury

Background

Spinal cord injury (SCI) triggers a robust neuroinflammatory response that governs secondary injury mechanisms with both degenerative and pro-regenerative effects. Identifying new immunomodulatory therapies to promote the supportive aspect of immune response is critically needed for the treatment of SCI. We previously demonstrated that SCI results in acute and permanent depletion of the neuronally derived Neuregulin-1 (Nrg-1) in the spinal cord. Increasing the dysregulated level of Nrg-1 through acute intrathecal Nrg-1 treatment enhanced endogenous cell replacement and promoted white matter preservation and functional recovery in rat SCI. Moreover, we identified a neuroprotective role for Nrg-1 in moderating the activity of resident astrocytes and microglia following injury. To date, the impact of Nrg-1 on immune response in SCI has not yet been investigated. In this study, we elucidated the effect of systemic Nrg-1 therapy on the recruitment and function of macrophages, T cells, and B cells, three major leukocyte populations involved in neuroinflammatory processes following SCI.

Methods

We utilized a clinically relevant model of moderately severe compressive SCI in female Sprague-Dawley rats. Nrg-1 (2 μg/day) or saline was delivered subcutaneously through osmotic mini-pumps starting 30 min after SCI. We conducted flow cytometry, quantitative real-time PCR, and immunohistochemistry at acute, subacute, and chronic stages of SCI to investigate the effects of Nrg-1 treatment on systemic and spinal cord immune response as well as cytokine, chemokine, and antibody production.

Results

We provide novel evidence that Nrg-1 promotes a pro-regenerative immune response after SCI. Bioavailability of Nrg-1 stimulated a regulatory phenotype in T and B cells and augmented the population of M2 macrophages in the spinal cord and blood during the acute and chronic stages of SCI. Importantly, Nrg-1 fostered a more balanced microenvironment in the injured spinal cord by attenuating antibody deposition and expression of pro-inflammatory cytokines and chemokines while upregulating pro-regenerative mediators.

Conclusion

We provide the first evidence of a significant regulatory role for Nrg-1 in neuroinflammation after SCI. Importantly, the present study establishes the promise of systemic Nrg-1 treatment as a candidate immunotherapy for traumatic SCI and other CNS neuroinflammatory conditions.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1093-9) contains supplementary material, which is available to authorized users.

Islet encapsulation with polyphenol coatings decreases pro-inflammatory chemokine synthesis and T cell trafficking

Type 1 Diabetes (T1D) is a chronic pro-inflammatory autoimmune disease consisting of islet-infiltrating leukocytes involved in pancreatic β-cell lysis. One promising treatment for T1D is islet transplantation; however, clinical application is constrained due to limited islet availability, adverse effects of immunosuppressants, and declining graft survival. Islet encapsulation may provide an immunoprotective barrier to preserve islet function and prevent immune-mediated rejection after transplantation. We previously demonstrated that a novel cytoprotective nanothin multilayer coating for islet encapsulation consisting of tannic acid (TA), an immunomodulatory antioxidant, and poly(N-vinylpyrrolidone) (PVPON), was efficacious in dampening in vitro immune responses involved in transplant rejection and preserving in vitro islet function. However, the ability of (PVPON/TA) to maintain islet function in vivo and reverse diabetes has not been tested. Recent evidence has demonstrated that modulation of redox status can affect pro-inflammatory immune responses. Therefore, we hypothesized that transplanted (PVPON/TA)-encapsulated islets can restore euglycemia to diabetic mice and provide an immunoprotective barrier. Our results demonstrate that (PVPON/TA) nanothin coatings can significantly decrease in vitro chemokine synthesis and diabetogenic T cell migration. Importantly, (PVPON/TA)-encapsulated islets restored euglycemia after transplantation into diabetic mice. Our results demonstrate that (PVPON/TA)-encapsulated islets may suppress immune responses and enhance islet allograft acceptance in patients with T1D.

Information theoretic approach to complex biological network reconstruction: application to cytokine release in RAW 264.7 macrophages

BACKGROUND

High-throughput methods for biological measurements generate vast amounts of quantitative data, which necessitate the development of advanced approaches to data analysis to help understand the underlying mechanisms and networks. Reconstruction of biological networks from measured data of different components is a significant challenge in systems biology.

RESULTS

We use an information theoretic approach to reconstruct phosphoprotein-cytokine networks in RAW 264.7 macrophage cells. Cytokines are secreted upon activation of a wide range of regulatory signals transduced by the phosphoprotein network. Identifying these components can help identify regulatory modules responsible for the inflammatory phenotype. The information theoretic approach is based on estimation of mutual information of interactions by using kernel density estimators. Mutual information provides a measure of statistical dependencies between interacting components. Using the topology of the network derived, we develop a data-driven parsimonious input-output model of the phosphoprotein-cytokine network.

CONCLUSIONS

We demonstrate the applicability of our information theoretic approach to reconstruction of biological networks. For the phosphoprotein-cytokine network, this approach not only captures most of the known signaling components involved in cytokine release but also predicts new signaling components involved in the release of cytokines. The results of this study are important for gaining a clear understanding of macrophage activation during the inflammation process.

Estrogen receptor β agonist diarylpropionitrile inhibits lipopolysaccharide-induced regulated on activation normal T cell expressed and secreted (RANTES) production in macrophages by repressing nuclear factor κB activation

OBJECTIVE

To investigate the effect of the estrogen receptor-β (ERβ) agonist diarylpropionitrile (DPN) on lipopolysaccharide (LPS)-induced regulated on activation normal T cell expressed and secreted (RANTES) production in macrophages and the possible mechanisms.

DESIGN

Cellular and molecular biology experimental study.

SETTING

University-based research laboratory.

PATIENT(S)

None.

INTERVENTION(S)

ERβ mRNA and protein expression determined in murine macrophage cell line RAW264.7 cells using reverse-transcription polymerase chain reaction and Western blot analysis; RANTES production detected by ELISA in LPS-stimulated RAW264.7 cells and ERβ knockdown RAW264.7 cells after the addition of DPN, phosphorylation of p65 and IκB degradation detected by Western blot analysis; and nuclear accumulation of p65 visualized using immunofluorescence.

MAIN OUTCOME MEASURE(S)

LPS-induced RANTES production and phosphorylation of p65 and IκB.

RESULT(S)

ERβ was expressed in RAW264.7 cells, and DPN statistically significantly decreased LPS-induced RANTES production in RAW264.7 cells. Small interfering RNA targeting the ERβ gene inhibited the effect of DPN on RANTES production. In addition, DPN inhibited nuclear translocation and phosphorylation of p65 by inhibiting IκB degradation and thus prohibited the activation of nuclear factor κB (NF-κB).

CONCLUSION(S)

Diarylpropionitrile down-regulates LPS-induced RANTES production via ERβ. This effect of DPN is likely due to repression of nuclear factor κB activation.

Molecular cloning of the porcine RANTES promoter: functional characterization of dsDNA/dsRNA response elements in PK-15 cells

The chemokine RANTES plays an essential role in inflammation and immune response. In this study, we cloned the nucleotide sequence of the 5'-flanking region of the porcine RANTES (poRANTES) gene and characterized the regulatory elements that activate transcription. Analyses of a series of 5' deletion constructs demonstrated that a 266 bp region (-220/+46) that spanned the potential transcription start site of the poRANTES gene was sufficient to activate transcription in PK-15 cells. Furthermore, our results indicated that dsDNA/dsRNA significantly induced poRANTES promoter activity and expression of mRNA levels in a time- and dose-dependent manner. Promoter deletions and mutagenesis experiments indicated that an interferon-stimulated responsive element (ISRE) was critical for dsDNA/dsRNA-induced poRANTES transcription. In addition, porcine interferon regulatory factor 3 (IRF-3) and IRF-7 play important roles in dsDNA/dsRNA-induced poRANTES expression.

Bile acids induce inflammatory genes in hepatocytes: a novel mechanism of inflammation during obstructive cholestasis

Inflammation contributes to liver injury during cholestasis. The mechanism by which cholestasis initiates an inflammatory response in the liver, however, is not known. Two hypotheses were investigated in the present studies. First, activation of Toll-like receptor 4 (TLR4), either by bacterial lipopolysaccharide or by damage-associated molecular pattern molecules released from dead hepatocytes, triggers an inflammatory response. Second, bile acids act as inflammagens, and directly activate signaling pathways in hepatocytes that stimulate production of proinflammatory mediators. Liver inflammation was not affected in lipopolysaccharide-resistant C3H/HeJ mice after bile duct ligation, indicating that Toll-like receptor 4 is not required for initiation of inflammation. Treatment of hepatocytes with bile acids did not directly cause cell toxicity but increased the expression of numerous proinflammatory mediators, including cytokines, chemokines, adhesion molecules, and other proteins that influence immune cell levels and function. Up-regulation of several of these genes in hepatocytes and in the liver after bile duct ligation required early growth response factor-1, but not farnesoid X receptor. In addition, early growth response factor-1 was up-regulated in the livers of patients with cholestasis and correlated with levels of inflammatory mediators. These data demonstrate that Toll-like receptor 4 is not required for the initiation of acute inflammation during cholestasis. In contrast, bile acids directly activate a signaling network in hepatocytes that promotes hepatic inflammation during cholestasis.

Data-driven modeling of cellular stimulation, signaling and output response in RAW 264.7 cells

Background

Understanding the relative importance of signaling pathway components which regulate a specific cellular response is a major focus of current efforts in biology. This interest, along with the inherit complexity of these systems, is driving the development of approaches capable of providing both quantitative predictions as well as guiding the design of future experiments. Of particular interest is the establishment of methods for the analysis of cellular-level input-output signaling relationships that have been characterized over time.

Results

Work by the Alliance for Cellular Signaling (AfCS) has provided an extensive profile of ligand-induced changes in protein phosphorylation state and cytokine output response in macrophage-like RAW 264.7 cells. Using model averaging with partial least squares (PLS) or principal components regression (PCR), we compared multivariate models quantitatively predicting cytokine release and identifying key regulatory components of the underlying signaling pathways. We paid particular attention to the effect of metrics extracted from the experimentally derived signaling time courses so as to determine whether the inclusion of such temporal information improved model predictions. Results indicate that we were able to determine the key biological predictors responsible for generating a specific cytokine response, with model R² values ranging from 0.48 to 0.93. Furthermore, for this data set, the use of time metrics was found to be of mixed value, with increased and/or more appropriate sampling likely being required to improve predictive performance.

Conclusion

The use of multivariate approaches and model averaging provides a valuable predictive framework for quantitative studies of these complex biological processes. Results of this work also point to several issues for consideration in the design of similar large-scale interrogations.

Mycobacterium bovis bacillus Calmette-Guerin induces CCL5 secretion via the Toll-like receptor 2-NF-kappaB and -Jun N-terminal kinase signaling pathways

In response to Mycobacterium bovis bacillus Calmette-Guérin (BCG), CC chemokines are secreted from host cells to attract components of the innate and adaptive immune systems to the site of infection. Toll-like receptor 2 (TLR2) has been shown to recognize M. bovis BCG and to initiate signaling pathways that result in enhanced secretion of CC chemokines. Despite the essential requirement of TLR2 in M. bovis BCG infection, the mechanisms by which it induces secretion of CC chemokines are not well defined. In this study, we report that stimulation of HEK293 cells expressing human TLR2 with M. bovis BCG resulted in increased CCL2 and CCL5 secretion, as determined by an enzyme-linked immunosorbent assay. M. bovis BCG infection resulted in the activation of c-Jun N-terminal kinase (JNK), and the inhibition of JNK activity had a significant effect on M. bovis BCG-dependent CCL5 secretion in TLR2-expressing cells but no effect on M. bovis BCG-dependent CCL2 secretion from infected HEK293 cells expressing human TLR2. The M. bovis BCG-induced CCL5 release was attenuated by sulfasalazine (a well-described inhibitor of NF-kappaB activity), BAY 11-7082 (an IkappaB phosphorylation inhibitor), and ALLN (a well-described inhibitor of NF-kappaB activation that prevents degradation of IkappaB and eventually results in a lack of translocated NF-kappaB in the nucleus). In addition, stimulation of TLR2-expressing cells with M. bovis BCG resulted in translocation of NF-kappaB subunits from the cytoplasmic to the nuclear fraction, and stimulation of cells with M. bovis BCG activated IkappaB kinase alphabeta. These findings indicate that M. bovis BCG induces CCL5 production through mechanisms that include a TLR2-dependent component that requires JNK and NF-kappaB activities.

Silibinin polarizes Th1/Th2 immune responses through the inhibition of immunostimulatory function of dendritic cells

Silibinin is the primary active compound in silymarin. It has been demonstrated to exert anti-carcinogenic effects and hepato-protective effects. However, the effects of silibinin on the maturation and immunostimulatory activities exhibited by dendritic cells (DCs) remain, for the most part, unknown. In this study, we have attempted to determine whether silibinin can influence surface molecule expression, dextran uptake, cytokine production, capacity to induce T-cell differentiation, and the signaling pathways underlying these phenomena in murine bone marrow-derived DCs. Silibinin was shown to significantly suppress the expression of CD80, CD86, MHC class I, and MHC class II in the DCs, and was also associated with impairments of LPS-induced IL-12 expression in the DCs. Silibinin-treated DCs proved highly efficient with regard to Ag capture via mannose receptor-mediated endocytosis. Silibinin also inhibited the LPS-induced activation of MAPKs and the nuclear translocation of the NF-kappaB p65 subunit. Additionally, silibinin-treated DCs evidenced an impaired induction of Th1 response, and a normal cell-mediated immune response. These findings provide new insight into the immunopharmacological functions of silibinin, especially with regard to their impact on the DCs. These findings expand our current understanding of the immunopharmacological functions of silibinin, and may prove useful in the development of therapeutic adjuvants for acute and chronic DC-associated diseases.

Identification of signaling components required for the prediction of cytokine release in RAW 264.7 macrophages

BACKGROUND

Release of immuno-regulatory cytokines and chemokines during inflammatory response is mediated by a complex signaling network. Multiple stimuli produce different signals that generate different cytokine responses. Current knowledge does not provide a complete picture of these signaling pathways. However, using specific markers of signaling pathways, such as signaling proteins, it is possible to develop a 'coarse-grained network' map that can help understand common regulatory modules for various cytokine responses and help differentiate between the causes of their release.

RESULTS

Using a systematic profiling of signaling responses and cytokine release in RAW 264.7 macrophages made available by the Alliance for Cellular Signaling, an analysis strategy is presented that integrates principal component regression and exhaustive search-based model reduction to identify required signaling factors necessary and sufficient to predict the release of seven cytokines (G-CSF, IL-1alpha, IL-6, IL-10, MIP-1alpha, RANTES, and TNFalpha) in response to selected ligands. This study provides a model-based quantitative estimate of cytokine release and identifies ten signaling components involved in cytokine production. The models identified capture many of the known signaling pathways involved in cytokine release and predict potentially important novel signaling components, like p38 MAPK for G-CSF release, IFNgamma- and IL-4-specific pathways for IL-1a release, and an M-CSF-specific pathway for TNFalpha release.

CONCLUSION

Using an integrative approach, we have identified the pathways responsible for the differential regulation of cytokine release in RAW 264.7 macrophages. Our results demonstrate the power of using heterogeneous cellular data to qualitatively and quantitatively map intermediate cellular phenotypes.

Use of a fluorescent phosphoprotein dye to characterize oxidative stress-induced signaling pathway components in macrophage and epithelial cultures exposed to diesel exhaust particle chemicals

A large body of evidence has shown that exposure to ambient particulate matter (PM) leads to asthma exacerbation through an excitation of allergic inflammation. Utilizing diesel exhaust particles (DEPs) as a model air pollutant, we and others have demonstrated that PM contains redox-active chemicals that generate inflammation through an oxidative stress mechanism. Recently, the strengths of proteomics have enabled us to demonstrate that organic DEP extracts induce a hierarchical expression pattern of oxidative stress-induced proteins in macrophages and epithelial cells. As a further extension of this work, we now employ a new phosphosensor fluorescent dye, Pro-Q Diamond, to elucidate the induction of phosphoproteins and intracellular signaling cascades that may play a role in DEP-induced inflammation. We demonstrate that DEPs induced the phosphorylation of several phosphoproteins that belong to a number of signaling pathways as well as other oxidative stress pathways. In combination with cytokine array, phosphoproteome analysis using Pro-Q Diamond allowed us to characterize the aromatic and polar chemicals of DEPs that are involved in the activation of three different mitogen-activated protein (MAP) kinase signaling pathways.

Chronic fuel oil toxicity in American mink (Mustela vison): systemic and hematological effects of ingestion of a low-concentration of bunker C fuel oil

Petroleum oil enters the coastal marine environment through various sources; marine mammals such as sea otters that inhabit this environment may be exposed to low concentrations of petroleum hydrocarbons through ingestion of contaminated prey. The inability to perform controlled studies in free-ranging animals hinders investigations of the effects of chronic petroleum oil exposure on sea otter morbidity and mortality, necessitating the development of a reliable laboratory model. We examined the effects of oral exposure to 500 ppm bunker C fuel oil over 113-118 days on American mink, a species phylogenetically related to the sea otter. Hematological parameters and organs were examined for fuel oil-associated changes. Hepatic cytochrome P4501A1 mRNA expression and fecal cortisol concentrations were also measured. Ingestion of fuel oil was associated with a decrease in erythrocyte count, hemoglobin concentration (Hgb), hematocrit (HCT), and an increase in mean corpuscular volume (MCV). Total leukocytes were elevated in the fuel oil group from increases in neutrophils, lymphocytes, and monocytes. Significant interactions between fuel oil and antigen challenge were found for erythrocyte parameters, monocyte and lymphocyte counts. Liver and adrenal weights were increased although mesenteric lymph node weights were decreased in the fuel oil group. Hepatic cytochrome P4501A1 mRNA was elevated in the fuel oil group. Fecal cortisol concentration did not vary between the two groups. Our findings show that fuel oil exposure alters circulating leukocyte numbers, erythrocyte homeostasis, hepatic metabolism and adrenal physiology and establish a framework to use mink as a model for sea otters in studying the systemic effects of marine contaminants.

Toll-like receptor 4 mediates inflammatory signaling by bacterial lipopolysaccharide in human hepatic stellate cells

Bacterial lipopolysaccharide (LPS) stimulates Kupffer cells and participates in the pathogenesis of alcohol-induced liver injury. However, it is unknown whether LPS directly affects hepatic stellate cells (HSCs), the main fibrogenic cell type in the injured liver. This study characterizes LPS-induced signal transduction and proinflammatory gene expression in activated human HSCs. Culture-activated HSCs and HSCs isolated from patients with hepatitis C virus-induced cirrhosis express LPS-associated signaling molecules, including CD14, toll-like receptor (TLR) 4, and MD2. Stimulation of culture-activated HSCs with LPS results in a rapid and marked activation of NF-kappaB, as assessed by in vitro kinase assays for IkappaB kinase (IKK), IkappaBalpha steady-state levels, p65 nuclear translocation, NF-kappaB-dependent luciferase reporter gene assays, and electrophoretic mobility shift assays. Lipid A induces NF-kappaB activation in a similar manner. Both LPS- and lipid A-induced NF-kappaB activation is blocked by preincubation with either anti-TLR4 blocking antibody (HTA125) or Polymyxin B. Lipid A induces NF-kappaB activation in HSCs from TLR4-sufficient (C3H/OuJ) mice but not from TLR4-deficient (C3H/HeJ) mice. LPS also activates c-Jun N-terminal kinase (JNK), as assessed by in vitro kinase assays. LPS up-regulates IL-8 and MCP-1 gene expression and secretion. LPS-induced IL-8 secretion is completely inhibited by the IkappaB super repressor (Ad5IkappaB) and partially inhibited by a specific JNK inhibitor, SP600125. LPS also up-regulates cell surface expression of ICAM-1 and VCAM-1. In conclusion, human activated HSCs utilize components of TLR4 signal transduction cascade to stimulate NF-kappaB and JNK and up-regulate chemokines and adhesion molecules. Thus, HSCs are a potential mediator of LPS-induced liver injury.

Potential interaction between CCR1 and its ligand, CCL3, induced by endogenously produced interleukin-1 in human hepatomas

Hepatoma cell lines can produce a massive amount of chemokines in response to various stimuli including hepatitis viruses and their products. However, it remains elusive on the types of chemokine receptor(s) expressed in the hepatoma tissues and its roles in hepatoma development. To clarify these points, we examined the chemokine receptor expression in six human hepatoma cell lines. All of the hepatoma cell lines constitutively and exclusively expressed CCR1 mRNA and its protein on their cell surface. CCR1 expression was also detected on hepatoma cells and to a lesser degree, on endothelial cells in hepatoma tissues but not in normal liver tissues. Furthermore, CCL3 expression was detected in hepatoma cells, endothelial cells, and to a lesser degree, fibroblast-like cells in hepatoma tissue, whereas only occasional vascular endothelial cells and inflammatory cells in normal liver tissues were weakly positive for CCL3. Moreover, the forskolin-mediated increases in intracellular cAMP concentrations were inhibited by the ligands for CCR1, CCL3, CCL4, and CCL5, suggesting that the expressed CCR1 was functional. Four hepatoma cell lines produced CCL3 only in response to interleukin (IL)-1 alpha and IL-1 beta. Finally, IL-1 alpha and IL-1 beta were detected abundantly in hepatoma tissues but not in normal liver tissues. Thus, IL-1 may enhance the local production of CCL3, which may interact with CCR1 expressed on hepatoma cells, in an autocrine and/or paracrine manner.

ESE-1, an enterocyte-specific Ets transcription factor, regulates MIP-3alpha gene expression in Caco-2 human colonic epithelial cells

We have previously shown that colonic epithelial cells are a major site of MIP-3alpha production in human colon and that enterocyte MIP-3alpha protein levels are elevated in inflammatory bowel disease. The aim of this study was to determine the molecular mechanisms regulating MIP-3alpha gene transcription in Caco-2 intestinal epithelial cells. We show that a kappaB element at nucleotides -82 to -93 of the MIP-3alpha promoter binds p50/p65 NF-kappaB heterodimers and is a major regulator of basal and interleukin-1beta (IL-1beta)-mediated gene activation. Scanning mutagenesis of the MIP-3alpha 5'-flanking region also identified two additional binding elements: Site X (nucleotides -63 to -69) and Site Y (nucleotides -143 to -154). Site X (CGCCTTC) bound Sp1 and regulated basal MIP-3alpha gene transcription. Overexpression of Sp1 increased basal luciferase activity, whereas, substitutions in the Sp1 element significantly reduced reporter activity. In contrast, Site Y (AAGCAGGAAGTT) regulated both basal and cytokine-induced gene activation and bound the Ets nuclear factor ESE-1. Substitutions in the Site Y element markedly reduced inducible MIP-3alpha reporter activity. Conversely, overexpression of ESE-1 significantly up-regulated MIP-3alpha luciferase levels. Taken together, our findings demonstrate that co-ordinate activation and binding of ESE-1, Sp1, and NF-kappaB to the MIP-3alpha promoter is required for maximal gene expression by cytokine-stimulated Caco-2 human intestinal epithelial cells.

Regulation of RANTES promoter activation in alveolar epithelial cells after cytokine stimulation

Regulated on activation, normal T cell expressed, and presumably secreted (RANTES) is a member of the CC chemokine family of proteins implicated in a variety of diseases characterized by lung eosinophilia and inflammation, strongly produced by stimulated airway epithelial cells. Because such cytokines as tumor necrosis factor (TNF)-alpha and interferon-gamma (IFN-gamma) have been shown to enhance RANTES induction in airway epithelial cells and RANTES gene expression appears to be differentially regulated depending on the cell type and the stimulus applied, in this study we have elucidated mechanisms that operate to control RANTES induction on exposure to TNF-alpha and/or IFN-gamma. Our results indicate that TNF-alpha and IFN-gamma synergistically induce RANTES protein secretion and mRNA expression. RANTES transcription is activated only after stimulation with TNF-alpha, but not IFN-gamma, which affects RANTES mRNA stabilization. Promoter deletion and mutagenesis experiments indicate that the nuclear factor (NF)-kappaB site is the most important cis-regulatory element controlling TNF-induced RANTES transcription, although NF-interleukin-6 binding site, cAMP responsive element (CRE), and interferon-stimulated responsive element (ISRE) also play a significant role. TNF-alpha stimulation induces nuclear translocation of interferon regulatory factor (IRF)-3, which in viral infection binds the RANTES ISRE and is necessary for activation of RANTES transcription. However, TNF-induced IRF-3 translocation does not result in IRF-3 binding to the RANTES ISRE. Although viral infection can activate an ISRE-driven promoter, TNF cannot, indicating that RANTES gene enhancers are controlled in a stimulus-specific fashion. Identification of molecular mechanisms involved in RANTES gene expression is fundamental for developing strategies to modulate lung inflammatory responses.

Roles of toll-like receptors in C-C chemokine production by renal tubular epithelial cells

Pyelonephritis, in which renal tubular epithelial cells are directly exposed to bacterial component, is a major predisposing cause of renal insufficiency. Although previous studies have suggested C-C chemokines are involved in the pathogenesis, the exact source and mechanisms of the chemokine secretion remain ambiguous. In this study, we evaluated the involvement of Toll-like receptors (TLRs) in C-C chemokine production by mouse primary renal tubular epithelial cells (MTECs). MTECs constitutively expressed mRNA for TLR1, 2, 3, 4, and 6, but not for TLR5 or 9. MTECs also expressed MD-2, CD14, myeloid differentiation factor 88, and Toll receptor-IL-1R domain-containing adapter protein/myeloid differentiation factor 88-adapter-like. Synthetic lipid A and lipoprotein induced monocyte chemoattractant protein 1 (MCP-1) and RANTES production in MTECs, which strictly depend on TLR4 and TLR2, respectively. In contrast, MTECs were refractory to CpG-oligodeoxynucleotide in chemokine production, consistently with the absence of TLR9. LPS-mediated MCP-1 and RANTES production in MTECs was abolished by NF-kappaB inhibition, but unaffected by extracellular signal-regulated kinase inhibition. In LPS-stimulated MTECs, inhibition of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase significantly decreased RANTES, but did not affect MCP-1 mRNA induction. Thus, MTECs have a distinct expression pattern of TLR and secrete C-C chemokines in response to direct stimulation with a set of bacterial components.

Oxidative stress and peritoneal endometriosis

OBJECTIVE

To review the literature associating pelvic endometriosis with oxidative stress and to discuss the potential causes and consequences of a pro-oxidant environment in the peritoneal cavity.

DESIGN

Literature survey.

RESULT(S)

Several studies suggest that oxidative stress is a component of the inflammatory reaction associated with endometriosis. Evidence includes the prevention of endometriosis induction in rabbits by the addition of antioxidants, an increase in reactive oxygen species release by macrophages, increased peritoneal levels of oxidized low-density lipoproteins and their by-products, altered expression of endometrial pro-oxidant and antioxidant enzymes, and consumption of peritoneal fluid vitamin E. Retrograde menstruation is likely to carry highly pro-oxidant factors, such as heme and iron, into the peritoneal cavity, as well as apoptotic endometrial cells, which are well-known inducers of oxidative stress. Reactive oxygen species may be involved in endometriosis-associated infertility and may play a role in the regulation of the expression of genes encoding immunoregulators, cytokines and cell adhesion molecules implicated in the pathogenesis of endometriosis.

CONCLUSION(S)

Better understanding of the mechanisms of reactive oxygen species production and detoxification and further investigation of their effect on the peritoneal environment are essential to obtain new insight into this disease and eventually develop new diagnostic and therapeutic strategies.

Thiol antioxidants inhibit the adjuvant effects of aerosolized diesel exhaust particles in a murine model for ovalbumin sensitization

Although several epidemiological studies indicate a correlation between exposure to ambient particulate matter and adverse health effects in humans, there is still a fundamental lack of understanding of the mechanisms involved. We set out to test the hypothesis that reactive oxygen species are involved in the adjuvant effects of diesel exhaust particles (DEP) in a murine OVA sensitization model. First, we tested six different antioxidants, N-acetylcysteine (NAC), bucillamine (BUC), silibinin, luteolin, trolox (vitamin E), and ascorbic acid, for their ability to interfere in DEP-mediated oxidative stress in vitro. Of the six agents tested, only the thiol antioxidants, BUC and NAC, were effective at preventing a decrease in intracellular reduced glutathione:glutathione disulfide ratios, protecting cells from protein and lipid oxidation, and preventing heme oxygenase 1 expression. Therefore, we selected the thiol antioxidants for testing in the murine OVA inhalation sensitization model. Our data demonstrate that NAC and BUC effectively inhibited the adjuvant effects of DEP in the induction of OVA-specific IgE and IgG1 production. Furthermore, NAC and BUC prevented the generation of lipid peroxidation and protein oxidation in the lungs of OVA- plus DEP-exposed animals. These findings indicate that NAC and BUC are capable of preventing the adjuvant effects of inhaled DEP and suggest that oxidative stress is a key mechanistic component in the adjuvant effect of DEP. Antioxidant treatment strategies may therefore serve to alleviate allergic inflammation and may provide a rational basis for treating the contribution of particulate matter to asthmatic disease.

A novel mitogen-activated protein kinase phosphatase is an important negative regulator of lipopolysaccharide-mediated c-Jun N-terminal kinase activation in mouse macrophage cell lines

We have isolated a cDNA homologous to known dual-specificity phosphatases from a mouse macrophage cDNA library and termed it MKP-M (for mitogen-activated protein kinase phosphatase isolated from macrophages). Three other presumed splice variant isoforms have also been identified for MKP-M. The longest and most abundant mRNA contains an open reading frame corresponding to 677 amino acids and produces an 80-kDa protein. The deduced amino acid sequence of MKP-M is most similar to those of hVH-5 (or mouse M3/6) and VHP1, a Caenorhabditis elegans tyrosine phosphatase. It includes an N-terminal rhodanase homology domain, the extended active-site sequence motif (V/L)X(V/I)HCXAG(I/V)SRSXT(I/V)XXAY(L/I)M (where X is any amino acid), and a C-terminal PEST sequence. Northern blot analysis revealed a dominant MKP-M mRNA species of approximately 5.5 kb detected ubiquitously among all tissues examined. MKP-M was constitutively expressed in mouse macrophage cell lines, and its expression levels were rapidly increased by lipopolysaccharide (LPS) stimulation but not by tumor necrosis factor alpha (TNF-alpha), gamma interferon, interleukin-2 (IL-2), or IL-15 stimulation. Immunocytochemical analysis showed MKP-M to be present within cytosol. When expressed in COS7 cells, MKP-M blocks activation of mitogen-activated protein kinases with the selectivity c-Jun N-terminal kinase (JNK) >> p38 = extracellular signal-regulated kinase. Furthermore, expression of a catalytically inactive form of MKP-M in a mouse macrophage cell line increased the intensity and duration of JNK activation and TNF-alpha secretion after LPS stimulation, suggesting that MKP-M is at least partially responsible for the desensitization of LPS-mediated JNK activation and cytokine secretion in macrophages.

Multiple cis regulatory elements control RANTES promoter activity in alveolar epithelial cells infected with respiratory syncytial virus

Respiratory syncytial virus (RSV) produces intense pulmonary inflammation, in part through its ability to induce chemokine synthesis in infected airway epithelial cells. RANTES (regulated upon activation, normally T-cell expressed and presumably secreted) is a CC chemokine which recruits and activates monocytes, lymphocytes, and eosinophils, all cell types present in the lung inflammatory infiltrate induced by RSV infection. In this study, we analyzed the mechanism of RSV-induced RANTES promoter activation in human type II alveolar epithelial cells (A549 cells). Promoter deletion and mutagenesis experiments indicate that RSV requires the presence of five different cis regulatory elements, located in the promoter fragment spanning from -220 to +55 nucleotides, corresponding to NF-kappaB, C/EBP, Jun/CREB/ATF, and interferon regulatory factor (IRF) binding sites. Although site mutations of the NF-kappaB, C/EBP, and CREB/AP-1 like sites reduce RSV-induced RANTES gene transcription to 50% or less, only mutations affecting IRF binding completely abolish RANTES inducibility. Supershift and microaffinity isolation assays were used to identify the different transcription factor family members whose DNA binding activity was RSV inducible. Expression of dominant negative mutants of these transcription factors further established their central role in virus-induced RANTES promoter activation. Our finding that the presence of multiple cis regulatory elements is required for full activation of the RANTES promoter in RSV-infected alveolar epithelial cells supports the enhanceosome model for RANTES gene transcription, which is absolutely dependent on binding of IRF transcription factors. The identification of regulatory mechanisms of RANTES gene expression is fundamental for rational design of inhibitors of RSV-induced lung inflammation.

IL-1 induced chemokine production through the association of Syk with TNF receptor-associated factor-6 in nasal fibroblast lines

The fibroblasts stimulated by cytokines released the chemokine and recruited the infiltrating cells, including eosinophils, that play a key role in the pathogenesis of airway disease. We established the human fibroblast lines showing high Syk expression and the lines showing low Syk expression from pieces of nasal polyp. IL-1 induces the interaction of TNFR-associated factor (TRAF) 6 with IL-1R-associated kinase, which is rapidly recruited to the IL-1R after IL-1 induction, whereas TRAF2 participates in TNF-alpha-signaling. In the present study, we found that Syk played a different role in IL-1- and TNF-alpha-induced chemokine production through a signaling complex involving Syk and TRAF6. Overexpression of wild-type Syk by gene transfer enhanced RANTES production from nasal fibroblasts stimulated with IL-1. The decrease of Syk expression by the administration of Syk antisense inhibited RANTES production in response to IL-1. However, the change of Syk expression did not affect RANTES production by TNF-alpha stimulation. We concluded that Syk is required for the IL-1-induced chemokine production through the association with TRAF-6 in fibroblasts of nasal polyps.

Two waves of nuclear factor kappaB recruitment to target promoters

Proinflammatory stimuli induce the rapid and transient translocation of nuclear factor (NF)-kappaB to the nucleus, where it activates transcription from several genes, including those encoding inflammatory cytokines and chemokines, adhesion molecules, and cytoprotective proteins. Using chromatin immunoprecipitation, we show that after an acute stimulation two distinct waves of NF-kappaB recruitment to target promoters occur: a fast recruitment to constitutively and immediately accessible (CIA) promoters and a late recruitment to promoters requiring stimulus-dependent modifications in chromatin structure to make NF-kappaB sites accessible (promoters with regulated and late accessibility [RLA]). Our results suggest that a mechanism of specificity in NF-kappaB-dependent transcriptional responses relies on the ability of individual stimuli to make RLA promoters accessible to NF-kappaB before its rapid extrusion from the nucleus.

Protein-tyrosine kinase Syk expressed in human nasal fibroblasts and its effect on RANTES production

Fibroblasts, a rich source of chemokines, interact with eosinophils and play a key role in the pathogenesis of airway disease. RANTES is produced by fibroblasts to attract and activate eosinophils. LPS is known to induce RANTES and cause protein tyrosine phosphorylation. Nonreceptor protein tyrosine kinase Syk is widely expressed and an important role in intracellular signal transduction in hemopoietic cells. In the present study, we examined whether Syk was expressed in a number of primary human nasal polyp tissue-derived fibroblast lines and whether it played some role in cellular function. Syk proteins were expressed in human nasal fibroblasts, but the expression level varied. There were positive correlations between the level of Syk expression and RANTES production induced by LPS. Overexpression of wild-type Syk by gene transfer enhanced RANTES production from nasal fibroblasts stimulated with LPS. The decrease of Syk expression by the administration of Syk antisense inhibited RANTES production. These results suggest that Syk expression affects RANTES production in fibroblasts of nasal polyps.

The role of particulate pollutants in pulmonary inflammation and asthma: evidence for the involvement of organic chemicals and oxidative stress

We review the literature indicating that the adverse health effects of ambient particulate matter involve the generation of oxidative stress and inflammation, as well as immunomodulating effects by particle-associated chemicals. We discuss evidence that diesel exhaust particle organic extracts induce reactive oxygen species in macrophages and bronchial epithelial cells, two key cell types targeted by particulate matter in the lung. Reactive oxygen species activate the promoters of cytokines and chemokines involved in allergic inflammation through activator protein-1 and nuclear factor- kappaB signaling pathways, which may explain exacerbation of allergic inflammation. Organic diesel exhaust particle chemicals also induce apoptosis and necrosis in bronchial epithelial cells via a mitochondrial pathway. This may be responsible for epithelial shedding and bronchial hyperreactivity in asthma.

Signaling by environmental polycyclic aromatic hydrocarbons in human lymphocytes

During the past decade there has been significant progress made in understanding how environmental agents, drugs, certain chemicals present in the diet, and occupational agents affect the immune system of animals and humans. Polycyclic aromatic hydrocarbons (PAHs) are an important class of environmentally prevalent xenobiotics that exert complex effects on the immune system. These agents, typified by benzo(a)pyrene (BaP), have been shown to alter antigen and mitogen receptor signaling pathways, leading to suppression of humoral and cell-mediated immunity, and at high exposure levels to activation of genes involved in apoptosis in lymphoid cells. Interestingly, at low exposure levels, PAHs may actually augment cell signaling pathways, resulting in immune enhancement or an adjuvant effect. While the biochemical targets and mechanisms responsible for immune modulation are still under investigation, several themes are evolving. PAHs, principally through their cytochrome-P450-derived metabolites, activate oxidative and electrophilic signaling pathways in lymphoid and nonlymphoid cells, including myeloid, epithelial, and other cells. Although PAHs affect signaling pathways in nonlymphoid cells leading to complex interactions between antigen-specific and nonspecific immune and inflammatory responses, this brief review focuses on the mechanisms of signaling by environmentally prevalent PAHs in human lymphocytes. Understanding the mechanisms by which xenobiotics alter adaptive and nonadaptive immune responses may shed light on the etiology of environmental and occupational immune diseases.

p38 mitogen-activated protein kinase and c-jun-NH2-terminal kinase regulate RANTES production by influenza virus-infected human bronchial epithelial cells

Airway epithelial cells which are the initial site of influenza virus (IV) infection are suggested to participate in airway inflammatory response by expressing various cytokines including RANTES; however, the intracellular signal that regulates RANTES expression has not been determined. In the present study, we examined the role of p38 mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase (Erk), and c-Jun-NH2-terminal kinase (JNK) in RANTES production by IV-infected human bronchial epithelial cells. The results showed that IV infection induced increases in p38 MAP kinase, and Erk and JNK phosphorylation and activity. SB 203580, PD 98059, and CEP-1347 attenuated IV-infection induced p38 MAP kinase activity, Erk activity, and JNK activity, respectively. SB 203580 and CEP-1347 attenuated RANTES production by 45.3% and 45.2%, respectively, but a combination of these inhibitors additively attenuated by 69.1%. In contrast, PD 98059 did not attenuate. Anti-IL-1alpha mAb, anti-IL-1beta mAb, anti-TNF-alpha mAb, anti-IL-8 mAb, anti-IFN-beta mAb, anti-RANTES mAb, and a combination of these mAbs did not affect IV infection-induced increases in p38 MAP kinase, Erk, and JNK phosphorylation, indicating that each cytokine neutralized by corresponding Ab was not involved in IV infection-induced phosphorylation of MAP kinases. N-acetylcysteine (NAC) did not affect IV infection-induced increases in MAP kinase phosphorylation, whereas NAC attenuated RANTES production by 18.2%, indicating that reactive oxygen species may act as a second messenger leading to RANTES production via p38 MAP kinase- and JNK-independent pathway. These results indicate that p38 MAP kinase and JNK, at least in part, regulate RANTES production by bronchial epithelial cells.

Enhancement of allergic inflammation by diesel exhaust particles: permissive role of reactive oxygen species

BACKGROUND

Diesel emission particulates (DEP) exert effects on the immune system and act as an adjuvant which enhances allergic inflammation. Animal and human models have delineated the effects of DEP chemicals in enhancing IgE production and promoting T-helper cell-2 (Th2) differentiation. An important primary effect that can explain the DEP-associated humoral and cellular immune responses is the induction of macrophage responses by DEP chemicals. This includes effects on macrophage production of cytokines and chemokines, which may play a role in enhancing allergic inflammation. A potent mechanism in macrophages exposed to DEP chemicals involves the generation of reactive oxygen species (ROS), leading to cellular activation or apoptosis which can be abrogated by antioxidants.

CONCLUSION

These findings may establish a role for antioxidant therapy in diminishing the effects of particulate pollutants in asthma.

Chemicals in Diesel Exhaust Particles Generate Reactive Oxygen Radicals and Induce Apoptosis in Macrophages

There is increasing evidence that particulate air pollutants, such as diesel exhaust particles (DEP), potentiate chronic inflammatory processes as well as acute symptomatic responses in the respiratory tract. The mechanisms of action as well as the cellular targets for DEP remain to be elucidated. We show in this paper that the phagocytosis of DEP by primary alveolar macrophages or macrophage cell lines, RAW 264.7 and THP-1, leads to the induction of apoptosis through generation of reactive oxygen radicals (ROR). This oxidative stress initiates two caspase cascades and a series of cellular events, including loss of surface membrane asymmetry and DNA damage. The apoptotic effect on macrophages is cell specific, because DEP did not induce similar effects in nonphagocytic cells. DEP that had their organic constituents extracted were no longer able to induce apoptosis or generate ROR. The organic extracts were, however, able to induce apoptosis. DEP chemicals also induced the activation of stress-activated protein kinases, which play a role in cellular apoptotic pathways. The injurious effects of native particles or DEP extracts on macrophages could be reversed by the antioxidant, N-acetyl-cysteine. Taken together, these data suggest that organic compounds contained in DEP may exert acute toxic effects via the generation of ROR in macrophages.

Primary Human CD4+ T Cells Contain Heterogeneous IκB Kinase Complexes: Role in Activation of the IL-2 Promoter

NF-κB transcription factors play an important role in the activation of the IL-2 gene in response to TCR ligation. The release of NF-κB factors to the nucleus requires phosphorylation and degradation of the inhibitory κ-B proteins (IκBs). IκBα and IκBβ phosphorylation is dependent on dual signaling by the TCR and the CD28 accessory receptor. This pathway involves a multisubunit IκB kinase (IKK) complex, which includes the IKKα (IKK-1) and IKKβ (IKK-2) kinases. We demonstrate that stimulation of primary human CD4+ T cells by CD3/CD28 activates two distinct endogenous IKK complexes, a heterodimeric IKKα/β and a homodimeric IKKβ complex. IKKβ overexpression in a Jurkat cell line resulted in the formation of a constitutively active IKK complex, which was CD3/CD28 inducible. In contrast, ectopic expression of IKKα assembled into a complex with negligible IκB kinase activity. Moreover, IKKβ, but not IKKα, overexpression enhanced transcriptional activation of the CD28 response element in the IL-2 promoter. Conversely, only kinase-inactive IKKβ interfered in the activation of the IL-2 promoter. Sodium salicylate, an inhibitor of IKKβ, but not IKKα, activity, inhibited IL-2 promoter activation as well as IL-2 secretion and interfered in activation of both the heterodimeric as well as the homodimeric IKK complexes in primary CD4+ T cells. Taken together, these data demonstrate the presence of an IKKβ-mediated signaling pathway that is activated by TCR and CD28 coligation and regulates IL-2 promoter activity.

The Jun Kinase Cascade Is Responsible for Activating the CD28 Response Element of the IL-2 Promoter: Proof of Cross-Talk with the IκB Kinase Cascade

Costimulation of TCR/CD3 and CD28 receptors leads to activation of the Jun kinase (JNK) cascade, which plays a key role in T cell activation, including activation of the IL-2 promoter. We demonstrate that the JNK cascade plays a central role in the activation of the CD28 response element (CD28RE) in the IL-2 promoter. This response element is linked to an activating protein-1 (AP-1) site, which functions synergistically with the CD28RE. The role of the JNK cascade in the activation of this composite element is twofold: 1) activation of the AP-1 site through transcriptional activation of c-Jun, and 2) activation of the CD28RE through selective cross-talk with IκB kinase-β (IKKβ). Dominant-negative versions of JNK kinase, c-Jun, and IKKβ interfered in CD3- plus CD28-induced CD28RE/AP-1 luciferase activity in Jurkat cells. In contrast, the dominant-active JNK kinase kinase, MEKK1, induced CD28RE/AP-1 luciferase activity, in parallel with induction of c-Jun and c-Rel binding to this combined promoter site. Dominant-active MEKK1 also induced transfected IKKβ, but not IKKα, activity. In contrast to the JNK cascade, the extracellular signal-regulated kinase (ERK) cascade did not exert an affect on the CD28RE/AP-1 site, but did contribute to activation of the distal NF-AT/AP-1 site.