A Paradigm for Gene Regulation: Inflammation, NF-κB and PPAR

Chronic inflammation in the cystic fibrosis lung: alterations in inter- and intracellular signaling

A vicious cycle of airway obstruction, infection, and inflammation continues to cause most of the morbidity and mortality in cystic fibrosis (CF). Mutations that result in decreased expression or function of the membrane Cl(-) channel, cystic fibrosis transmembrane regulator (CFTR), result in a decrease in the volume (and hence the depth) of liquid on the airway surface, impaired ciliary function, and dehydrated glandular secretions. In turn, these abnormalities contribute to a milieu, which promotes chronic infection with a limited but unique spectrum of microorganisms. Defects in CFTR also perturb regulation of several intracellular signaling pathways including signal transducers and activator of transcription, I-kappaB and nuclear factor-kappa B, and low molecular weight GTPases. Together, these abnormalities result in excessive production of NF-kappaB dependent cytokines such as interleukin (IL)-1, tumor necrosis factor (TNF), IL-6, and IL-8. There are decreased responses to interferon gamma and transforming growth factor beta leading to decreased production of iNOS and NO. Abnormalities of lipid mediators and decreased secretion of counter/regulatory cytokines have also been reported. Together, these effects combine to create a chronic inflammatory process, which damages and obstructs the airways, and eventually claims the life of the patient.

Angiotensin II-inducible platelet-derived growth factor-D transcription requires specific Ser/Thr residues in the second zinc finger region of Sp1

Sp1, the first identified and cloned transcription factor, regulates gene expression via multiple mechanisms including direct protein-DNA interactions, protein-protein interactions, chromatin remodeling, and maintenance of methylation-free CpG islands. Sp1 is itself regulated at different levels, for example, by glycosylation, acetylation, and phosphorylation by kinases such as the atypical protein kinase C-zeta. Although Sp1 controls the basal and inducible regulation of many genes, the posttranslational processes regulating its function and their relevance to pathology are not well understood. Here we have used a variety of approaches to identify 3 amino acids (Thr668, Ser670, and Thr681) in the zinc finger domain of Sp1 that are modified by PKC-zeta and have generated novel anti-peptide antibodies recognizing the PKC-zeta-phosphorylated form of Sp1. Angiotensin II, which activates PKC-zeta phosphorylation (at Thr410) via the angiotensin II type 1 receptor, stimulates Sp1 phosphorylation and increases Sp1 binding to the platelet-derived growth factor-D promoter. All 3 residues in Sp1 (Thr668, Ser670, and Thr681) are required for Sp1-dependent platelet-derived growth factor-D activation in response to angiotensin II. Immunohistochemical analysis revealed that phosphorylated Sp1 is expressed in smooth muscle cells of human atherosclerotic plaques and is dynamically expressed together with platelet-derived growth factor-D in smooth muscle cells of the injured rat carotid artery wall. This study provides new insights into the regulatory mechanisms controlling the PKC-zeta-phospho-Sp1 axis and angiotensin II-inducible gene expression.

Peroxisome proliferator-activated receptor alpha regulates skin inflammation and humoral response in atopic dermatitis

BACKGROUND

The peroxisome proliferator-activated receptors (PPARs) alpha, beta/delta, and gamma are ligand-activated transcription factors belonging to the nuclear receptor superfamily. In addition to their regulatory role on lipid and glucose metabolism, they exert anti-inflammatory properties. In skin both PPAR-alpha and PPAR-beta/delta regulate keratinocyte proliferation/differentiation and contribute to wound healing. The 3 PPAR isoforms are expressed by several cell types recruited into the dermis during inflammation.

OBJECTIVE

We have investigated the role of PPAR-alpha in the regulation of atopic dermatitis (AD), a common skin inflammatory disease.

METHODS

We chose a mouse model of inflammatory dermatosis with immunologic features of AD and used epicutaneous sensitization with ovalbumin in the absence of adjuvant, which mimics the human pathology.

RESULTS

On antigen sensitization, PPAR-alpha-deficient mice display increased epidermal thickening, dermal recruitment of inflammatory cells, lung inflammation, airway hyperresponsiveness, and IgE and IgG2a production compared with their wild-type counterparts. Increased inflammation was correlated to an enhancement of TH2 and, to a greater extent, TH1 responses and to increased skin expression of nuclear factor kappaB. Interestingly, PPAR-alpha expression was decreased in eczematous skin from patients with AD compared with skin from nonatopic donors, suggesting that defective PPAR-alpha expression might contribute to the pathology. Topical application of WY14643, a specific PPAR-alpha agonist, significantly decreased antigen-induced skin inflammation in the AD model.

CONCLUSION

PPAR-alpha acts as a negative regulator of skin inflammation in AD.

Inhibition of vascular inflammation by dehydroepiandrosterone sulfate in human aortic endothelial cells: roles of PPARalpha and NF-kappaB

Dehydroepiandrosterone sulfate (DHEAS) is a hormone produced by the adrenal gland and is a precursor for both androgens and estrogens. Atherosclerosis is a well characterized inflammatory disease, but little is known about the role of DHEAS in vascular inflammation. We hypothesize that DHEAS can reduce inflammation in vascular endothelial cells and the mechanism involves the peroxisome proliferator-activated receptor alpha (PPARalpha), thereby inhibiting transcription factors involved in endothelial cell inflammation. To test our hypothesis, aortic endothelial cells were pretreated for 48 h with DHEAS, then with TNF-alpha. TNF-alpha-induced upregulation of the expression of inflammatory genes interleukin (IL)-8 and intracellular adhesion molecule (ICAM)-1 was attenuated by incubation with DHEAS. DHEAS inhibited the TNF-alpha-induced surface expression of vascular cell adhesion molecule (VCAM)-1. This effect was abolished by the addition of MK866, a PPARalpha inhibitor, indicating that PPARalpha is involved in the mechanism of this inhibition. The addition of the aromatase inhibitor letrozole had no effect on the inhibition of TNF-alpha-induced VCAM-1 expression by DHEAS. Treatment of endothelial cells with DHEAS dramatically inhibited the TNF-alpha-induced activation of NF-kappaB, an inflammatory transcription factor, and increased protein levels of the NF-kappaB inhibitor, IkappaB-alpha. These results signify the ability of DHEAS to directly inhibit the inflammatory process and show a potential direct effect of DHEAS on vascular inflammation that has implications for the development of atherosclerotic cardiovascular disease.

Autophosphorylation docking site Tyr-867 in Mer receptor tyrosine kinase allows for dissociation of multiple signaling pathways for phagocytosis of apoptotic cells and down-modulation of lipopolysaccharide-inducible NF-kappaB transcriptional activation

Efficient clearance of apoptotic cells is essential for tissue homeostasis, allowing for cellular turnover without inflammatory consequences. The Mer (Nyk and c-Eyk) receptor tyrosine kinase (Mertk) is involved in two aspects of apoptotic cell clearance by acting as a receptor for Gas6, a gamma-carboxylated phosphatidylserine-binding protein that bridges apoptotic and viable cells. First, Mertk acts in a bona fide engulfment pathway in concert with alphavbeta5 integrin by regulating cytoskeletal assemblages, and second, it acts as a negative regulator for inflammation by down-modulating pro-inflammatory signals mediated from bacterial lipopolysaccharide-Toll-like receptor 4 (TLR4) signaling, and hence recapitulating anti-inflammatory immune modulation by apoptotic cells. Here we describe Mertk post-receptor events that govern phagocytosis and cytoskeletal signaling are principally mediated by autophosphorylation site Tyr-867. Using the Mertk Y867F mutant and pharmacological inhibitors, we show that Tyr-867 is required for phosphatidylinositol 3-kinase and phospholipase Cgamma2 activation; their activation in turn elicits protein kinase C-dependent signals that act on the actin cytoskeleton. Although Mertk(Y867F) blocked the tyrosine phosphorylation of FAK on Tyr-861 and p130(cas) and also abrogated the phagocytosis of apoptotic cells, this mutant did not suppress lipopolysaccharide-inducible NF-kappaB transcription, nor was NF-kappaB activation dependent on the protein kinase C inhibitor, calphostin C. Finally, unlike the cytoskeletal events associated with Tyr-867 autophosphorylation, the trans-inhibition of NF-kappaB occurred in a postnuclear-dependent fashion independent of cytosolic IkappaB phosphorylation and p65/RelA sequestration. Taken together, these data suggest that Mertk has distinct and separable effects for phagocytosis and for resolving inflammation, providing a molecular rationale for how immune licensing and inflammation can be dissociated from phagocytosis in a single phagocytic receptor.

Microbial Products Stimulate Human Toll-like Receptor 2 Expression through Histone Modification Surrounding a Proximal NF-κB-binding Site

Previous studies have yielded conflicting results regarding the ability of microbial products to activate TLR2 gene expression in human monocytes. In this study, we found that TLR2 mRNA was rapidly up-regulated in human monocytes treated with TLR2 and TLR4 agonists, and this corresponded to an increase in cell surface receptor levels. This induction was abrogated by actinomycin D as well as a pharmacologic inhibitor of NF-kappaB, suggesting that the TLR2 gene is transcriptionally activated via NF-kappaB. Microbial agonists were found to shift the transcription initiation site of the TLR2 gene, and sequence examination revealed a near-consensus NF-kappaB-binding element immediately upstream of this site. Electromobility shift assays confirmed that NF-kappaB bound to this putative site in vitro. However, luciferase reporter plasmids driven by the TLR2 promoter were not responsive to TLR2 agonists. Overexpression of the NF-kappaB p65 subunit was sufficient to induce expression of the endogenous TLR2 mRNA, and co-transfection of the CREB-binding protein and p300 co-activators further increased TLR2 mRNA levels. Chromatin immunoprecipitation analysis revealed that p65, CREB-binding protein, and p300 are recruited to the TLR2 promoter upon stimulation of human monocytes followed by histone hyperacetylation. Taken together, these results define a mechanism whereby histone modification and increased promoter access induce expression of human TLR2 following infection.

Sputum biomarkers of inflammation in cystic fibrosis lung disease

Pulmonary biomarkers are being used more frequently to monitor disease activity and evaluate response to treatment in individuals with cystic fibrosis (CF). This article summarizes the current state of knowledge of biomarkers of inflammation relevant to CF lung disease, and the tools to measure inflammation, with specific emphasis on sputum. Sputum is a rich, noninvasive source of biomarkers of inflammation and infection. Sputum induction, through the inhalation of hypertonic saline, has expanded the possibilities for monitoring airway inflammation and infection, especially in individuals who do not routinely expectorate sputum. We critically examine the existing data supporting the validity of sputum biomarkers in CF, with an eye toward their application as surrogate endpoints or outcome measures in CF clinical trials. Further validation studies are needed regarding the variability of inflammatory biomarker measurements, and to evaluate how these biomarkers relate to disease severity, and to longitudinal changes in lung function and other clinical endpoints. We highlight the need to incorporate sputum collection, by induction if necessary, and measurement of sputum biomarkers into routine CF clinical care. In the future, pulmonary biomarkers will likely be useful in predicting disease progression, indicating the onset and resolution of a pulmonary exacerbation, and assessing response to current therapies or candidate therapeutics.

Epigenetic silencing of tumor necrosis factor alpha during endotoxin tolerance

Sustained silencing of potentially autotoxic acute proinflammatory genes like tumor necrosis factor alpha (TNFalpha) occurs in circulating leukocytes following the early phase of severe systemic inflammation. Aspects of this gene reprogramming suggest the involvement of epigenetic processes. We used THP-1 human promonocytes, which mimic gene silencing when rendered endotoxin-tolerant in vitro, to test whether TNFalpha proximal promoter nucleosomes and transcription factors adapt to an activation-specific profile by developing characteristic chromatin-based silencing marks. We found increased TNFalpha mRNA levels in endotoxin-responsive cells that was preceded by dissociation of heterochromatin-binding protein 1alpha, demethylation of nucleosomal histone H3 lysine 9 (H3(Lys(9))), increased phosphorylation of the adjacent serine 10 (H3(Ser(10))), and recruitment of NF-kappaB RelA/p65 to the TNFalpha promoter. In contrast, endotoxin-tolerant cells repressed production of TNFalpha mRNA, retained binding of heterochromatin-binding protein 1alpha, sustained methylation of H3(Lys(9)), reduced phosphorylation of H3(Ser(10)), and showed diminished binding of NF-kappaB RelA/p65 to the TNFalpha promoter. Similar levels of NF-kappaB p50 occurred at the TNFalpha promoter in the basal state, during active transcription, and in the silenced phenotype. RelB, which acts as a repressor of TNFalpha transcription, remained bound to the promoter during silencing. These results support an immunodeficiency paradigm where epigenetic changes at the promoter of acute proinflammatory genes mediate their repression during the late phase of severe systemic inflammation.

Inflammation and anti-inflammatory therapies for cystic fibrosis

Cystic fibrosis lung disease is characterized by a self-propagating cycle of obstruction, infection, and inflammation. The inflammatory response, which accounts for the majority of the morbidity and mortality of the disease, begins early in life, becomes persistent, and is excessive relative to the bacterial burden. Therapies aimed at decreasing the inflammatory response represent a relatively new strategy for treatment. This article reviews the current state of the art of anti-inflammatory therapy in cystic fibrosis and introduces clinical trials that are underway.

Peroxisome proliferator-activated receptor alpha protects against obesity-induced hepatic inflammation

Recently it has become evident that obesity is associated with low-grade chronic inflammation. The transcription factor peroxisome proliferator-activated receptor alpha (PPARalpha) has been shown to have a strong antiinflammatory action in liver. However, the role of PPARalpha in obesity-induced inflammation is much less clear. Therefore, the aim of our study was to determine whether PPARalpha plays a role in obesity-induced hepatic inflammation. To induce obesity, wild-type sv129 and PPARalpha(-/-) mice were exposed to a chronic high-fat diet (HFD), using a low-fat diet (LFD) as control. In wild-type mice, HFD significantly increased the hepatic and adipose expression of numerous genes involved in inflammation. Importantly, this effect was amplified in PPARalpha(-/-) mice, suggesting an antiinflammatory role of PPARalpha in liver and adipose tissue. Further analysis identified specific chemokines and macrophage markers, including monocyte chemotactic protein 1 and F4/80(+), that were elevated in liver and adipose tissue of PPARalpha(-/-) mice, indicating increased inflammatory cell recruitment in the knockout animals. When all groups of mice were analyzed together, a significant correlation between hepatic triglycerides and expression of inflammatory markers was observed. Many inflammatory genes that were up-regulated in PPARalpha(-/-) livers by HFD were down-regulated by treatment with the PPARalpha ligand Wy-14643 under normal nonsteatotic conditions, either in vivo or in vitro, suggesting an antiinflammatory effect of PPARalpha that is independent of reduction in liver triglycerides. In conclusion, our results suggest that PPARalpha protects against obesity-induced chronic inflammation in liver by reducing hepatic steatosis, by direct down-regulation of inflammatory genes, and by attenuating inflammation in adipose tissue.

The Interleukin-6 inflammation pathway from cholesterol to aging--role of statins, bisphosphonates and plant polyphenols in aging and age-related diseases

We describe the inflammation pathway from Cholesterol to Aging. Interleukin 6 mediated inflammation is implicated in age-related disorders including Atherosclerosis, Peripheral Vascular Disease, Coronary Artery Disease, Osteoporosis, Type 2 Diabetes, Dementia and Alzheimer's disease and some forms of Arthritis and Cancer. Statins and Bisphosphonates inhibit Interleukin 6 mediated inflammation indirectly through regulation of endogenous cholesterol synthesis and isoprenoid depletion. Polyphenolic compounds found in plants, fruits and vegetables inhibit Interleukin 6 mediated inflammation by direct inhibition of the signal transduction pathway. Therapeutic targets for the control of all the above diseases should include inhibition of Interleukin-6 mediated inflammation.

PPARs and molecular mechanisms of transrepression

In the last few years, PPARs have emerged as key regulators of inflammatory and immune responses. However, the mechanistic basis of the anti-inflammatory effects of peroxisome proliferator-activated receptors (PPARs) remains poorly understood. Accumulating evidence suggests that these effects result from inhibition of signal-dependent transcription factors that mediate inflammatory programs of gene activation. Several mechanisms underlying negative regulation of gene expression by PPARs have been described. Recent studies, using siRNA, microarray analysis and macrophage-specific knockout mice, have highlighted PPARs molecular transrepression mechanism in macrophages. Identification of their mechanism of action should help promote the understanding of the physiologic roles that PPARs play in immunity and contribute to the development of new therapeutic agents.

Immunohistochemical evaluation of phosphorylated SMAD2/SMAD3 and the co-activator P300 in human glomerulonephritis: correlation with renal injury

BACKGROUND

Smad2 and Smad3 are transcription factors that mediate transforming growth factor beta (TGF-beta) signals. Upon their activation, phosphorylated Smad2/Smad3 (pSmad2/Smad3), translocate to the nucleus and associate with co-activators such as p300, regulating the transcription of genes that contribute to the fibrotic processes.

METHODS

We investigated the immunohistochemical expression of pSmad2/Smad3 and the co-activator p300 in 152 renal biopsy specimens from patients with various types of glomerulonephritides (GNs) and in 15 normal kidney specimens. Patients' clinical data (serum creatinine levels and proteinuria) had been collected.

RESULTS

There was a dramatic increase in the expression of pSmad2/3 and p300 in all glomerular cell types in all GNs. pSmad2/3 expression was increased in all tubular segments (except for the proximal tubules in nonproliferative GNs), while p300 expression was significantly increased only in the proximal tubular cells in all GNs. Glomerular and tubular pSmad2/Smad3 and p300 were significantly increased in proliferative GNs (compared to the nonproliferative), particularly in the secondary group. The expression profile of p300 correlated positively with the expression of pSmad2/Smad3 in the diseased glomeruli and proximal tubules. pSmad2/3 and p300 were very often detected in segmental hyperplastic lesions, cellular crescents, microadhesions and segmental or global sclerotic areas. Glomerular and proximal tubular pSmad2/Smad3 was positively correlated with serum creatinine levels, while distal and collecting tubular pSmad2/3 and p300 correlated positively with tubular atrophy. Glomerular and proximal tubular pSmad2/3 expression and glomerular p300 expression correlated positively with lupus nephritis activity.

CONCLUSION

Our results suggest that pSmad2/3-p300 pathway may play a pivotal role in the pathogenesis and progression of human glomerulonephritis.

Gender differences in renal nuclear receptors and aryl hydrocarbon receptor in 5/6 nephrectomized rats

This study was aimed at delineating molecular pathways essential in gender-different pathogenesis of chronic kidney diseases (CKD). Renal transcripts of nuclear receptors and metabolic enzymes in male and female kidneys from 5/6 nephrectomized (Nx) rats 7 weeks post-Nx were examined using branched DNA signal amplification assay. Nx-males had marked kidney injury coupled with anemia and malnutrition. Nx-females had moderate renal injury, and were free of albuminuria, anemia, and malnutrition. Nx-males had systemic and renal inflammation, which were largely absent in Nx-females. Blood 17beta-estradiol, testosterone, and corticosterone did not change, whereas urinary testosterone decreased in both genders. Compared to males, female kidneys had higher androgen receptor (AR) and aryl hydrocarbon receptor (AhR) but lower estrogen receptor alpha (ERalpha). Compared to Nx-males, female remnant kidneys had less decreases in ERalpha and peroxisome proliferator-activated receptor alpha (PPARalpha), had no induction of AR and decrease of acyl-CoA oxidase, whereas had induction of cytochrome P450 4a1 (Cyp4a1) but decrease of AhR. Renal protein expression of a 52-kDa isoform of Wilm's tumor 1 (WT1), transcription factor critical in nephrogenesis, decreased dramatically in Nx-males but largely preserved in Nx-females. In conclusion, gender divergences in basal expression and alteration of ERalpha, AR, AhR, WT1, and PPARalpha/Cyp4a1 during CKD may explain gender differences in CKD progression and outcome of renal transplantation.

Genes invoked in the ovarian transition to menopause

Menopause and the associated declines in ovarian function are major health issues for women. Despite the widespread health impact of this process, the molecular mechanisms underlying the aging-specific decline in ovarian function are almost completely unknown. To provide the first gene-protein analysis of the ovarian transition to menopause, we have established and contrasted RNA gene expression profiles and protein localization and content patterns in healthy young and perimenopausal mouse ovaries. We report a clear distinction in specific mRNA and protein levels that are noted prior to molecular evidence of steroidogenic failure. In this model, ovarian reproductive aging displays similarities with chronic inflammation and increased sensitivity to environmental cues. Overall, our results indicate the presence of mouse climacteric genes that are likely to be major players in aging-dependent changes in ovarian function.

Adaptive mechanisms to oxidative stress during aging

Whether or not oxidative stress is the cause of the aging process, as proposed by the oxidative stress theory of aging remains unknown; but accumulated evidence overwhelmingly identifies increased oxidative stress with age as a source of damage to cellular structure and function. From an evolutionary perspective, the utilization of oxygen as a life supporting means makes oxidative stress an inescapable part of an organism's biological system. The inseparability of oxidative stress from the biological system can be viewed as an adaptive response that all aerobic organisms undergo to ward-off the potentially harmful effects of oxygen and its derivatives, including free radicals. The organism's adaptive mechanisms include an intricate network of defenses that regulate and guard against any over-acting oxidative reactions to ensure its survival. This review discusses and illustrates several adaptive responses at various levels (from gene regulation to physical exercise) that organisms use as part of their survival strategy.

Calcitonin gene-related peptide inhibits interleukin-1beta-induced endogenous monocyte chemoattractant protein-1 secretion in type II alveolar epithelial cells

As important multifunctional cells in the lung, alveolar epithelial type II (AEII) cells secrete numerous chemokines on various stimuli. Our previous data showed that AEII cells also express the neuropeptide calcitonin gene-related peptide (CGRP) and the proinflammatory factor interleukin (IL)-1beta induces CGRP secretion in the A549 human AEII cell line. In the present study, the CGRP-1 receptor antagonist human (h)CGRP(8-37) (0.1-1 nM) greatly amplified the production of IL-1beta-induced monocyte chemoattractant protein (MCP)-1. The inhibition of CGRP expression by small interfering RNA significantly increased MCP-1 secretion on IL-1beta stimulation. However, exogenous hCGRP (10-100 nM) suppressed IL-1beta-evoked MCP-1 secretion in MCP-1 promoter activity, and CGRP gene stably transfected cell clones significantly inhibited both the mRNA and protein levels of MCP-1 induced by IL-1beta. These data imply that AEII-derived CGRP suppressed IL-1beta-induced MCP-1 secretion in an autocrine/paracrine mode. Subsequent investigation revealed that CGRP inhibited IL-1beta-evoked NF-kappaB activity by suppressing IkappaBalpha phosphorylation and degradation. Moreover, CGRP attenuated IL-1beta-induced reactive oxygen species (ROS) formation, the early event in proinflammatory factor signaling. We previously showed that the CGRP inhibitory effect was mediated by elevated intracellular cAMP and show here that analogs of cAMP, 8-bromoadenosine 3',5'-cyclic monophosphothioate and the Sp isomer of adenosine 3',5'-cyclic monophosphothioate, mimicked the CGRP suppressive effect on IL-1beta-induced ROS formation, NF-kappaB activation, and MCP-1 secretion. Thus increased endogenous CGRP secretion in lung inflammatory disease might eliminate the excessive response by elevating the cAMP level through inhibiting the ROS-NF-kappaB-MCP-1 pathway.

Gypenoside XLIX isolated from Gynostemma pentaphyllum inhibits nuclear factor-kappaB activation via a PPAR-alpha-dependent pathway

Nuclear factor (NF)-kappaB is important in the generation of inflammation. Besides regulating lipid metabolism, peroxisome proliferator-activated receptor (PPAR)-alpha activators also reduce NF-kappaB activation to terminate activation of inflammatory pathways. Gynostemma pentaphyllum (GP) has been used to treat various inflammatory diseases and hyperlipidemia. Here, we demonstrate that GP extract and one of its main components, Gypenoside XLIX (Gyp-XLIX) inhibited LPS-induced NF-kappaB activation in murine macrophages. Furthermore, Gyp-XLIX restored the LPS- and TNF-alpha-induced decrease in cytosolic I-kappaBalpha protein expression and inhibited the translocation of NF-kappaB(p65) to the nucleus in THP-1 monocyte and HUVEC cells. The inhibition of LPS- and TNF-alpha-induced NF-kappaB luciferase activity in macrophages was abolished by MK-886, a selective PPAR-alpha antagonist. GP extract and Gyp-XLIX (EC(50): 10.1 microM) enhanced PPAR-alpha luciferase activity in HEK293 cells transfected with the tK-PPREx3-Luc reporter plasmid and expression vectors for PPAR-alpha. Additionally, Gyp-XLIX specifically enhanced PPAR-alpha mRNA and protein expression in THP-1-derived macrophage cells. The selectivity of Gyp-XLIX for PPAR-alpha was demonstrated by the activation of only PPAR-alpha in HEK293 cells transfected with expression vectors for PPAR-alpha, PPAR-beta/delta or PPAR-gamma1 plasmids and in THP-1-derived macrophage naturally expressing all three PPAR isoforms. The present study demonstrates that Gyp-XLIX, a naturally occurring gynosaponin, inhibits NF-kappaB activation via a PPAR-alpha-dependent pathway.

PPAR gamma represses VEGF expression in human endometrial cells: implications for uterine angiogenesis

Endometrial vasculature supports physiological uterine growth, embryonic implantation and endometrial pathology. Vascular endothelial growth factor (VEGF) is regulated by diverse developmental and hormonal signals, including eicosanoid ligands of PPARgamma. The action of natural and synthetic PPARgamma ligands on VEGF expression in primary and transformed human endometrial cell cultures was established by quantifying endogenous gene expression and transfected VEGF gene reporters. VEGF promoter-luciferase constructs were truncated and mutated to map functional sequences. Endometrial tissues and cells express PPARgamma protein. Treatment of transformed and primary endometrial cells with rosiglitazone, a synthetic PPARgamma agonist, or prostaglandin 15-deoxy-Delta12-14 J(2), a naturally occurring eicosanoid ligand, decreased VEGF protein secretion. In transiently transfected Ishikawa cells, rosiglitazone repressed VEGF gene promoter-luciferase activation with an IC(50) approximately approximately 50 nM. Truncated and mutated VEGF promoter constructs revealed that the PPARgamma-regulated domain is a direct repeat (DR)-1 motif -443 bp upstream of the transcriptional start site.

CONCLUSIONS

PPARgamma ligands repress VEGF gene expression via a PPARgamma-responsive element (PPRE) in the VEGF gene promoter. Agonists of this nuclear receptor might be exploited pharmacologically to inhibit pathological vascularization in complications of pregnancy, endometriosis and endometrial adenocarcinoma.

Anti-inflammatory medications for cystic fibrosis lung disease: selecting the most appropriate agent

The lung disease of cystic fibrosis (CF) is characterized by a self-sustaining cycle of airway obstruction, infection, and inflammation. Therapies aimed at decreasing the inflammatory response represent a relatively new strategy for treatment. Attention has focused primarily upon the therapeutic potential of corticosteroids and NSAIDs. Although beneficial, the use of systemic corticosteroids is limited by their unacceptable adverse effects. It is unclear if inhaled corticosteroids are a viable alternative, although their use in CF has dramatically increased in recent years. High-dose ibuprofen has been shown to slow progression of CF lung disease, but its use has not been widely adopted despite a favorable risk-benefit profile. Thus, other anti-inflammatory approaches are under investigation. Since the inflammatory response can be triggered by many stimuli and since the pathways activated by these stimuli produce many mediators, there are a plethora of targets for anti-inflammatory therapeutics. Specific antibodies, receptor antagonists, and counter-regulatory cytokines, such as interleukin (IL)-10 and interferon-gamma, inhibit the pro-inflammatory mediators responsible for the damaging inflammation in the CF airway, including tumor necrosis factor-alpha, IL-1beta and IL-8. Studies of molecules that modulate intracellular signaling cascades that lead to the production of inflammatory mediators, are underway in CF. For patients with established disease, recent and projected advances in therapies that are directed at neutrophil products, such as DNase, antioxidants, and protease inhibitors, hold great promise for limiting the consequences of the inflammatory response. To optimize anti-inflammatory therapy, it is necessary to understand the mechanism of action of these agents in the CF lung to determine which agents will be most beneficial, and to determine which therapies should be initiated at what age and stage of lung disease. Hope remains that correction of the abnormal CF transmembrane conductance regulator protein or gene replacement therapy will be curative. However, correction of the basic defect must also correct the dysregulated inflammatory response in order to be effective. Until those therapies aimed at repairing the basic defect are realized, limiting the effects of the inflammatory process will be important in slowing the decline in lung function and thus prolonging survival in patients with CF.

Cytokines and the regulation of hypoxia-inducible factor (HIF)-1alpha

Hypoxia-inducible factor (HIF)--an oxygen sensor? The HIF-oxygen sensing association type of dogma is, unequivocally, well anchored. But this is only one face of, at least, a double-sided coin. Current concepts charge HIF of taking sides with a yet not well-founded identity--an immunologic sensor and/or regulator. Or, is it really a sensor, put it more correctly, a key player in sensing mechanisms? The evolving association between HIF and immunity emanates from an established linkage that bonds oxidative stress and inflammation--notably the 'biologic response modifiers', or cytokines. HIF is a redox(y)-sensitive transcription factor, and so are cytokines. Recently, cytokines emerged as major regulators of HIF, under physiologic conditions extending the realm of hypoxia. Alternatively, can HIF, like the so infamous inflammatory transcription factor NF-(kappa)B, prove itself as a key player in the regulation of cytokines and, subsequently, the inflammatory process. The targeting of HIF would be, at least theoretically, of therapeutic value, but does it make sense given its intricate role in hypoxia signaling? It is the theme of HIF being an immunologic sensor that will be explored therein--with special emphasis on the regulatory role of cytokines.

Anti-inflammatory effect of fibrate protects from cisplatin-induced ARF

Recently, we demonstrated that peroxisome proliferator-activated receptor-α (PPARα) ligand ameliorates cisplatin-induced acute renal failure (ARF) by preventing inhibition of substrate oxidation, and also by preventing apoptosis and necrosis of the proximal tubule (Li S, Bhatt R, Megyesi J, Gokden N, Shah SV, and Portilla D. Am J Physiol Renal Physiol 287: F990–F998, 2004). In the following studies, we examined the protective effect of PPARα ligand on cisplatin-induced inflammatory responses during ARF. Mice subjected to a single intraperitoneal injection of cisplatin developed ARF at day 3. Cisplatin increased mRNA and protein expression of TNF-α, RANTES, and also upregulated endothelial adhesion molecules ICAM-1/VCAM-1 and chemokine receptors CCR1/CCR5. Cisplatin also led to neutrophil infiltration in the corticomedullary region. Pretreatment of wild-type mice with WY-14,643, a fibrate class of PPARα ligands, before cisplatin significantly suppressed cisplatin-induced upregulation of cytokine/chemokine expression, prevented neutrophil accumulation, and ameliorated renal dysfunction. In contrast, treatment with PPARα ligand before cisplatin did not prevent cytokine/chemokine production, neutrophil accumulation, and did not protect kidney function in PPARα null mice. In addition, we observed that cisplatin-induced NF-κB binding activity in nuclear extracts from wild-type mice was markedly reduced by treatment with PPARα ligand. These results demonstrate that PPARα exerts an anti-inflammatory effect in kidney tissue by a mechanism that includes inhibition of NF-κB DNA binding activity, and this effect results in inhibition of neutrophil infiltration, cytokine/chemokine release, and amelioration of cisplatin-induced ARF.

Role of upstream stimulatory factor phosphorylation in the regulation of the prostaglandin G/H synthase-2 promoter in granulosa cells

To investigate the role of USF phosphorylation in the regulation of the PGHS-2 promoter in granulosa cells, promoter activity assays were performed in primary cultures of bovine granulosa cells transfected with the chimeric PGHS-2 promoter/luciferase (LUC) construct -149/-2PGHS-2.LUC. Transfections were done in the absence or presence of forskolin; the protein kinase A (PKA) inhibitor H-89; or an expression vector encoding USF1, USF2, the catalytic subunit of PKA (cPKA), or a PKA inhibitor protein (PKI). Electrophoretic mobility shift assays were performed to study USF/DNA interactions using granulosa cell nuclear extracts and a 32P-labeled proximal PGHS-2 promoter fragment containing the E-box element. The results show that forskolin stimulation and cPKA overexpression caused a marked and significant increase in USF-dependent DNA binding and PGHS-2 promoter activities (p < 0.05). In contrast, both activities were decreased by H-89 treatment or PKI overexpression. Reverse transcription-PCR analyses revealed that these treatments had similar effects on endogenous PGHS-2 mRNA levels in granulosa cells. Cotransfection studies with a USF2 mutant lacking N-terminal activation domains (U2Delta1-220) repressed forskolin-, cPKA-, and USF-dependent PGHS-2 promoter activities. Electrophoretic mobility shift assays showed that U2Delta1-220 was able to compete with full-length USF proteins and to saturate the E-box element. Immunoprecipitation/Western blot analyses revealed an increase in the levels of phosphorylated USF1 and USF2 after forskolin treatment, whereas chromatin immunoprecipitation assays showed that binding of USF proteins to the endogenous PGHS-2 promoter was stimulated by forskolin. Site-directed mutagenesis of a consensus PKA phosphorylation site within USF proteins abolished their transactivating capacity. Collectively, these results characterize the role of USF phosphorylation in PGHS-2 expression and identify the phosphorylation-dependent increase in USF binding to the E-box as a putative molecular basis for the increase in PGHS-2 promoter transactivation in granulosa cells.

Cardioprotective effects of peroxisome proliferator activated receptor gamma activators on acute myocarditis: anti-inflammatory actions associated with nuclear factor kappaB blockade

OBJECTIVE

To test the hypothesis that activation of peroxisome proliferator activated receptor gamma (PPAR-gamma) reduces experimental autoimmune myocarditis (EAM) associated with inhibitor kappaB (IkappaB) alpha induction, blockade of nuclear factor kappaB (NF-kappaB), and inhibition of inflammatory cytokine expression.

METHODS

EAM was induced in Lewis rats by immunisation with porcine cardiac myosin. PPAR-gamma activators 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) and pioglitazone (PIO) were administered to rats with EAM.

RESULTS

Enhanced PPAR-gamma expression was prominently stained in the nuclear and perinuclear regions of infiltrating inflammatory cells. Administration of 15d-PGJ2 and PIO greatly reduced the severity of myocarditis and suppressed myocardial mRNA and protein expression of inflammatory cytokines in rats with EAM. In addition, treatment with PPAR-gamma activators enhanced IkappaB concentrations in the cytoplasmic fractions and nuclear fractions from inflammatory myocardium. Concurrently, NF-kappaB was greatly activated in myocarditis; this activation was blocked in the 15d-PGJ2 treated and PIO treated groups.

CONCLUSIONS

PPAR-gamma may have a role in the pathophysiology of EAM. Because an increase in IkappaB expression and inhibition of translocation of the NF-kappaB subunit p65 to the nucleus in inflammatory cells correlated with the protective effects of PPAR-gamma activators, these results suggest that PPAR-gamma activators act sequentially through PPAR-gamma activation, IkappaB induction, blockade of NF-kappaB activation, and inhibition of inflammatory cytokine expression. These results suggest that PPAR-gamma activators such as 15d-PGJ2 and PIO may have the potential to modulate human inflammatory heart diseases such as myocarditis.

Enhanced RAGE-mediated NFkappaB stimulation in inflamed hemodialysis patients

Advanced glycation end-products (AGEs), a group of carbohydrate-derived compounds formed by non-enzymatic glycation and oxidation, are markedly elevated in end-stage renal disease (ESRD) and may be related to both inflammation and oxidative stress. The cellular effects of AGE are largely mediated by their interaction with specific surface receptors, such as RAGE. Measurements of biomarkers of inflammation and oxidative stress were conducted in 7 hemodialysis (HD) patients (5 males) with persistent high-grade inflammation (C-reactive protein [CRP]>10 mg/L) and 11 HD-patients (6 males) with low-grade inflammation (CRP<10 mg/L) for at least 6 months. Measured biomarkers for inflammation included hs-CRP, interleukin (IL)-6, white blood cells, neutrophils, S-albumin, peroxisome proliferator-activated receptors (PPAR alpha, beta, gamma) and nuclear factor kappaB (NFkappaB) activity. Markers for oxidative stress were advanced oxidation products (AOPP), myeloperoxidase (MPO)-activity, pentosidine and carboxymethyl lysine (CML). In addition, the effect of increasing doses of CML-modified human serum albumin on NFkappaB activity was tested in mononuclear cells isolated from each patient. As expected, HD-patients with high-grade inflammation had significantly elevated levels of IL-6 (median 9.2 pg/mL versus 2.5 pg/mL; p<0.01), MPO-activity (134.5+/-14.6 DeltaOD(630)/(min mg protein) versus 80.5+/-12.9 DeltaOD(630)/(min mg protein); p<0.05), PPAR-gamma (0.65+/-0.01 OD(655) versus 0.56+/-0.01 OD(655); p<0.01), and AOPP (269+/-54 microM versus 163+/-15 microM; p<0.05) compared with low-grade inflamed patients. Significant associations were demonstrated between hs-CRP and NFkappaB (rho=0.58; p<0.05), AOPP (rho=0.49; p<0.05) and PPAR-gamma (rho=0.62; p<0.05), respectively. In the patient group with high-grade inflammation, stimulation of mononuclear cells with CML-modified human serum albumin caused a rapid dose-dependent rise (p<0.0001) in NFkappaB activity that could be completely blocked by an anti-RAGE antibody. Inflammation and oxidative stress biomarkers are interrelated in ESRD. Inflammatory cell signal pathways, such as NFkappaB, are activated by CML-modification of proteins via RAGE.

Soy isoflavone phyto-pharmaceuticals in interleukin-6 affections. Multi-purpose nutraceuticals at the crossroad of hormone replacement, anti-cancer and anti-inflammatory therapy

Interleukin-6 is a pleiotropic cytokine which plays a crucial role in immune physiology and is tightly controlled by hormonal feedback mechanisms. After menopause or andropause, loss of the normally inhibiting sex steroids (estrogen, testosterone) results in elevated IL6 levels that are further progressively increasing with age. Interestingly, excessive IL6 production promotes tumorigenesis (breast, prostate, lung, colon, ovarian), and accounts for several disease-associated pathologies and phenotypical changes of advanced age, such as osteoporosis, rheumatoid arthritis, multiple myeloma, neurodegenerative diseases and frailty. In this respect, pharmacological modulation of IL6 gene expression levels may have therapeutical benefit in preventing cancer progression, ageing discomforts and restoring immune homeostasis. Although "plant extracts" are used in folk medicine within living memory, it is only since the 20th century that numerous scientific investigations have been performed to discover potential health-protective food compounds or "nutraceuticals" which might prevent cancer and ageing diseases. About 2000 years ago, Hippocrates already highlighted "Let food be your medicine and medicine be your food". Various nutrients in the diet play a crucial role in maintaining an "optimal" immune response, such that deficient or excessive intakes can have negative consequences on the organism's immune status and susceptibility to a variety of pathologies. Over the last few decades, various immune-modulating nutrients have been identified, which interfere with IL6 gene expression. Currently, a broad range of phyto-pharmaceuticals with a claimed hormonal activity, called "phyto-estrogens", is recommended for prevention of various diseases related to a disturbed hormonal balance (i.e. menopausal ailments and/or prostate/breast cancer). In this respect, there is a renewed interest in soy isoflavones (genistein, daidzein, biochanin) as potential superior alternatives to the synthetic selective estrogen receptor modulators (SERMs), which are currently applied in hormone replacement therapy (HRT). As phyto-chemicals integrate hormonal ligand activities and interference with signaling cascades, therapeutic use may not be restricted to hormonal ailments only, but may have applications in cancer chemoprevention and/or NF-kappaB-related inflammatory disorders as well.