Induction Of IκBα Research Articles

The Gastroprotective Effects of Anisomeles indica against Ethanol-Induced Gastric Ulcer through the Induction of IκB-α and the Inhibition of NF-κB Expression.

Anisomeles indica (L.) Kuntze is a traditional herb with multiple medicinal properties and with potential for preventing or treating various diseases. Acteoside, one of the active ingredients in A. indica, is prepared into commercially available products of A. indica HP813 powder. In this study, the gastroprotective effects of A. indica HP813 powder were evaluated. Wistar rats were treated with A. indica HP813 powder at doses of 0, 207.5, 415, and 830 mg/kg body weight for 28 days. Then, gastric ulcers were induced by the oral administration of 70% ethanol (10 mL/kg body weight) on day 28. The rats were sacrificed at the end of the trial, and stomach tissues were collected. These stomach tissues were then used for macroscopic, microscopic, and immunohistochemical analyses. The results indicated that the area of gastric ulcer was 48.61%, 35.30%, and 27.16% in the ethanol-induced group, 415 mg/kg A. indica HP813 powder group, and 830 mg/kg A. indica HP813 powder group, respectively. In addition, the lesion scores were 2.9, 2.4, and 2.3 in the ethanol-induced group, 415 mg/kg A. indica HP813 powder group, and 830 mg/kg A. indica HP813 powder group, respectively. The immunochemical staining of the gastric tissue revealed that A. indica HP813 powder reduced the expressions of TNF-α and NF-κB proteins in the gastric tissue, which had been induced by ethanol. Finally, A. indica HP813 powder protected the gastric ulcer from ethanol damage through IκB-α induction. The present results demonstrated that A. indica HP813 powder has protective effects against ethanol-induced gastric ulcer.

Circulating corticosterone levels mediate the relationship between acute ethanol intoxication and markers of NF-κB activation in male rats

Binge drinking is a harmful pattern of alcohol use that is associated with a number of serious health problems. Of particular interest are the rapid alterations in neuroimmune gene expression and the concurrent activation of the hypothalamic-pituitary-adrenal (HPA) axis activation associated with high intensity drinking. Using a rat model of acute binge-like ethanol exposure, the present studies were designed to assess the role of corticosterone (CORT) in ethanol-induced neuroimmune gene expression changes, particularly those associated with the NFκB signaling pathway, including rapid induction of IL-6 and IκBα, and suppression of IL-1β and TNFα gene expression evident after administration of moderate to high doses of ethanol (1.5–3.5 g/kg ip) during intoxication (3 h post-injection). Experiment 1 tested whether inhibition of CORT synthesis with metyrapone and aminoglutethimide (100 mg/kg each, sc) would block ethanol-induced changes in neuroimmune gene expression. Results indicated that rapid alterations in IκBα, IL-1β, and TNFα expression were completely blocked by pretreatment with the glucocorticoid synthesis inhibitors, an effect that was reinstated by co-administration of exogenous CORT (3.75 mg/kg) in Experiment 2. Experiment 3 assessed whether these rapid alterations in neuroimmune gene expression would be evident when rats were challenged with a subthreshold dose of ethanol (1.5 g/kg) in combination with 2.5 mg/kg CORT, which showed limited evidence for additive effects of low-dose CORT combined with a moderate dose of ethanol. Acute inhibition of mineralocorticoid (spironolactone) or glucocorticoid (mifepristone) receptors, alone (Experiment 4) or combined (Experiment 5) had no effect on ethanol-induced changes in neuroimmune gene expression, presumably due to poor CNS penetrance of these drugs. Finally, Experiments 6 and 7 showed that dexamethasone (subcutaneous; a GR agonist) recapitulated effects of ethanol. Overall, we conclude that ethanol-induced CORT synthesis and release is responsible for suppression of IL-1β, TNFα, and induction of IκBα in the hippocampus through GR signaling. Interventions designed to curb these changes may reduce drinking, and subdue detrimental neuroimmune activation induced by ethanol.

TGF-β signaling in diabetic nephropathy: An update

Abstract Diabetic nephropathy (DN) is a common complication in patients with diabetes and the leading cause of end-stage renal disease. Accumulating evidence shows that transforming growth factor beta-1 (TGF-β1) is a key mediator in the pathogenesis of DN. TGF-β1 binds to its receptors to activate canonical and noncanonical downstream signaling pathways to exert its biological activities. Among them, canonical Smad signaling is the major pathway responsible for the development of DN. In addition to TGF-β1, many stress molecules, such as advanced glycation end products (AGEs), angiotensin II (Ang II), and C-reactive protein (CRP), can also activate Mothers against decapentaplegic homologs (Smads) via the extracellular signal-regulated kinase (ERK)/p38 mitogen-activated protein kinase (MAPK) cross talk mechanism. Furthermore, TGF-β/Smad signaling can also cross talk with nuclear factor kappa B (NF-κB) signaling to regulate renal inflammation via the induction of IκBα by Smad7. In the context of renal fibrosis, Smad3 is pathogenic, while Smad2 and Smad7 are protective. TGF-β signaling also upregulates the pathogenic microRNAs (miRNAs) (namely, miR-21, miR-192, and miR-377) and long noncoding RNAs (lncRNAs) (namely, Erbb4-IR (intron region, IR), LncRNA9884, and Arid2-IR) but downregulates the protective miRNAs (namely, miR-29a/b and miR-200a) to mediate DN. Thus, targeting TGF-β signaling, either by blocking its ligand, its receptor (i.e., TGF-β receptor-2 [TGFBR2]), Smad3, and downstream miRNAs/lncRNAs or by overexpressing Smad7, has been shown to improve DN. In addition, pharmaceutically targeting TGF-β signaling using chemical inhibitors and traditional Chinese medicine (TCM), including Tangshen formula, Chaihuang-Yishen granule, and herbal extracts (berberine, asiatic acid, and naringenin), also shows renoprotective effect in diabetes. In summary, TGF-β signaling is a critical pathway leading to DN and may be a therapeutic target for combating DN.

Clonorchis sinensis excretory–secretory products regulate migration and invasion in cholangiocarcinoma cells via extracellular signal-regulated kinase 1/2/nuclear factor-κB-dependent matrix metalloproteinase-9 expression

Matrix metalloproteinase-9 plays an important role in the invasion and metastasis of various types of cancer cells. We have previously reported that excretory–secretory products from Clonorchis sinensis increases matrix metalloproteinase-9 expression. However, the regulatory mechanisms through which matrix metalloproteinase-9 expression affects cholangiocarcinoma development remain unclear. In the current study, we examined the potential role of excretory–secretory products in regulating the migration and invasion of various cholangiocarcinoma cell lines. We demonstrated that excretory–secretory products significantly induced matrix metalloproteinase-9 expression and activity in a concentration-dependent manner. Reporter gene and chromatin immunoprecipitation assays showed that excretory–secretory products induced matrix metalloproteinase-9 expression by enhancing the activity of nuclear factor-kappa B. Moreover, excretory–secretory products induced the degradation and phosphorylation of IκBα and stimulated nuclear factor-kappa B p65 nuclear translocation, which was regulated by extracellular signal-regulated kinase 1/2. Taken together, our findings indicated that the excretory–secretory product-dependent enhancement of matrix metalloproteinase-9 activity and subsequent induction of IκBα and nuclear factor-kappa B activities may contribute to the progression of cholangiocarcinoma.

Disruption of Smad4 impairs TGF-β/Smad3 and Smad7 transcriptional regulation during renal inflammation and fibrosis in vivo and in vitro

The mechanism by which TGF-β regulates renal inflammation and fibrosis is largely unclear; however, it is well accepted that its biological effects are mediated through Smad2 and Smad3 phosphorylation. Following activation, these Smads form heteromeric complex with Smad4 and translocate into the nucleus to bind and regulate the expression of target genes. Here we studied the roles of Smad4 to regulate TGF-β signaling in a mouse model of unilateral ureteral obstruction using conditional Smad4 knockout mice and in isolated Smad4 mutant macrophages and fibroblasts. Disruption of Smad4 significantly enhanced renal inflammation as evidenced by a greater CD45(+) leukocyte and F4/80(+) macrophage infiltration and upregulation of IL-1β, TNF-α, MCP-1, and ICAM-1 in the obstructed kidney and in IL-1β-stimulated macrophages. In contrast, deletion of Smad4 inhibited renal fibrosis and TGF-β1-induced collagen I expression by fibroblasts. Further studies showed that the loss of Smad4 repressed Smad7 transcription, leading to a loss of functional protein. This, in turn, inhibited IκBα expression but enhanced NF-κB activation, thereby promoting renal inflammation. Interestingly, deletion of Smad4 influenced Smad3-mediated promoter activities and the binding of Smad3 to the COL1A2 promoter, but not Smad3 phosphorylation and nuclear translocation, thereby inhibiting the fibrotic response. Thus, Smad4 may be a key regulator for the diverse roles of TGF-β1 in inflammation and fibrogenesis by interacting with Smad7 and Smad3 to influence their transcriptional activities in renal inflammation and fibrosis.

PPARα Activation Protects against Anti-Thy1 Nephritis by Suppressing Glomerular NF-κB Signaling

The vast increase of chronic kidney disease (CKD) has attracted considerable attention worldwide, and the development of a novel therapeutic option against a representative kidney disease that leads to CKD, mesangial proliferative glomerulonephritis (MsPGN) would be significant. Peroxisome proliferator-activated receptor α (PPARα), a member of the steroid/nuclear receptor superfamily, is known to perform various physiological functions. Recently, we reported that PPARα in activated mesangial cells exerted anti-inflammatory effects and that the deficiency of PPARα resulted in high susceptibility to glomerulonephritis. To investigate whether PPARα activation improves the disease activity of MsPGN, we examined the protective effects of a PPARα agonist, clofibrate, in a well-established model of human MsPGN, anti-Thy1 nephritis, for the first time. This study demonstrated that pretreatment with clofibrate (via a 0.02% or 0.1% clofibrate-containing diet) continuously activated the glomerular PPARα, which outweighed the PPARα deterioration associated with the nephritic process. The PPARα activation appeared to suppress the NF-κB signaling pathway in glomeruli by the induction of IκBα, resulting in the reduction of proteinuria and the amelioration of the active inflammatory pathologic glomerular changes. These findings suggest the antinephritic potential of PPARα-related medicines against MsPGN. PPARα-related medicines might be useful as a treatment option for CKD.

Human serum-derived hydroxy long-chain fatty acids exhibit anti-inflammatory and anti-proliferative activity

BackgroundCirculating levels of novel long-chain hydroxy fatty acids (called GTAs) were recently discovered in the serum of healthy subjects which were shown to be reduced in subjects with colorectal cancer (CRC), independent of tumor burden or disease stage. The levels of GTAs were subsequently observed to exhibit an inverse association with age in the general population. The current work investigates the biological activity of these fatty acids by evaluating the effects of enriched human serum extracts on cell growth and inflammation.MethodsGTAs were extracted from commercially available bulk human serum and then chromatographically separated into enriched (GTA-positive) and depleted (GTA-negative) fractions. SW620, MCF7 and LPS stimulated RAW264.7 cells were treated with various concentrations of the GTA-positive and GTA-negative extracts, and the effects on cell growth and inflammation determined.ResultsEnriched fractions resulted in poly-ADP ribose polymerase (PARP) cleavage, suppression of NFκB, induction of IκBα, and reduction in NOS2 mRNA transcript levels. In RAW264.7 mouse macrophage cells, incubation with enriched fractions prior to treatment with LPS blocked the induction of several pro-inflammatory markers including nitric oxide, TNFα, IL-1β, NOS2 and COX2.ConclusionsOur results show that human serum extracts enriched with endogenous long-chain hydroxy fatty acids possess anti-inflammatory and anti-proliferative activity. These findings support a hypothesis that the reduction of these metabolites with age may result in a compromised ability to defend against uncontrolled cell growth and inflammation, and could therefore represent a significant risk for the development of CRC.

Dietary soy and tea mitigate chronic inflammation and prostate cancer via NFκB pathway in the Noble rat model

Chronic inflammation and nuclear factor-kappa B (NFκB) have been implicated in prostate cancer development; thus, dietary factors that inhibit NFκB may serve as effective chemo-preventative agents. Prostate cancer risk is significantly lower in Asian countries compared to the United States, which has prompted interest in the potential chemopreventative action of Asian dietary components such as soy and green tea. This study examined the effects of dietary soy and tea on NFκB activation and inflammation in vivo using a hormone-induced rat model for prostate cancer. Male Noble rats implanted with estradiol and testosterone were divided into 4 dietary groups: control, soy, tea, or soy+tea. NFκB activation and inflammatory cytokines were measured post implantation. The combination of soy and tea suppressed NFκB p50 binding activity and protein levels via induction of IκBα. Soy and tea also decreased prostate inflammatory infiltration, increased Bax/BcL2 ratio and decreased protein expression of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1β compared to control. Soy and tea attenuated prostate malignancy by decreasing prostate hyperplasia. These effects were not apparent in groups treated with soy or tea alone. The ongoing in vivo studies thus far suggest that combination of foods, such as soy and tea, may inhibit hormone-induced proinflammatory NFκB signals that contribute to prostate cancer development.

Cultured hypothalamic neurons are resistant to inflammation and insulin resistance induced by saturated fatty acids

Hypothalamic inflammation induced by high-fat feeding causes insulin and leptin resistance and contributes to the pathogenesis of obesity. Since in vitro exposure to saturated fatty acids causes inflammation and insulin resistance in many cultured cell types, we determined how cultured hypothalamic neurons respond to this stimulus. Two murine hypothalamic neuronal cell cultures, N43/5 and GT1-7, were exposed to escalating concentrations of saturated fatty acids for up to 24 h. Harvested cells were evaluated for activation of inflammation by gene expression and protein content. Insulin-treated cells were evaluated for induction of markers of insulin receptor signaling (p-IRS, p-Akt). In both hypothalamic cell lines, inflammation was induced by prototypical inflammatory mediators LPS and TNFalpha, as judged by induction of IkappaBalpha (3- to 5-fold) and IL-6 (3- to 7-fold) mRNA and p-IkappaBalpha protein, and TNFalpha pretreatment reduced insulin-mediated p-Akt activation by 30% (P < 0.05). By comparison, neither mixed saturated fatty acid (100, 250, or 500 microM for <or=6 h) nor palmitate exposure alone (200 microM for <or=24 h) caused inflammatory activation or insulin resistance in cultured hypothalamic neurons, whereas they did in control muscle and endothelial cell lines. Despite the lack of evidence of inflammatory signaling, saturated fatty acid exposure in cultured hypothalamic neurons causes endoplasmic reticulum stress, induces mitogen-activated protein kinase, and causes apoptotic cell death with prolonged exposure. We conclude that saturated fatty acid exposure does not induce inflammatory signaling or insulin resistance in cultured hypothalamic neurons. Therefore, hypothalamic neuronal inflammation in the setting of DIO may involve an indirect mechanism mediated by saturated fatty acids on nonneuronal cells.

Effects of soy and tea on hormone‐induced prostate cancer in Noble rat model

Chronic inflammation and NFκB have been implicated in prostate cancer development; thus, dietary factors that inhibit NFκB may serve as effective chemo‐preventative agents. Prostate cancer risk is significantly lower in Asian countries compared to the US, which has prompted the interest in the potential chemopreventative action of Asian diets. This study examines the effects of dietary soy and tea on the NFκB activation, inflammation and tumor development in vivo using a hormone‐induced rat model for prostate cancer. Male Noble rats implanted with estradiol and testosterone were divided into 4 dietary groups: control, soy, tea, or soy+tea diet. NFκB activity and inflammatory cytokines were measured post implantation. At 20 and 38 wk post‐implantation, prostate hyperplasia and prostatic intraepithelial neoplasia (PIN) were also assessed. The combination of soy and tea suppressed NFκB p50 binding activity and decreased NFκB p65 and p50 protein levels via induction of IκBα. Soy and tea also decreased prostate hyperplasia, increased Bax expression, and decreased gene expression of IL6 and IL1β compared to control. These effects were not apparent in groups treated with soy or tea alone. The ongoing in vivo studies thus far suggest that combination of foods, like soy and tea, may inhibit hormone‐induced pro‐inflammatory NFκB signals that contribute to prostate cancer development.

In vivobinding of NF-κB to the IκBβ promoter is insufficient for transcriptional activation

Despite certain structural and biochemical similarities, differences exist in the function of the NF-kappaB (nuclear factor kappaB) inhibitory proteins IkappaBalpha (inhibitory kappaBalpha) and IkappaBbeta. The functional disparity arises in part from variance at the level of gene regulation, and in particular from the substantial induction of IkappaBalpha, but not IkappaBbeta, gene expression post-NF-kappaB activation. In the present study, we probe the differential effects of IL (interleukin)-1beta on induction of IkappaBalpha and perform the first characterization of the human IkappaBbeta promoter. A consensus NF-kappaB-binding site, capable of binding NF-kappaB both in vitro and in vivo, is found in the IkappaBbeta gene 5' flanking region. However, the IkappaBbeta promoter was not substantially activated by pro-inflammatory cytokines, such as IL-1beta and tumour necrosis factor alpha, that are known to cause strong activation of NF-kappaB. Furthermore, in contrast with IkappaBalpha, NF-kappaB activation did not increase expression of endogenous IkappaBbeta as assessed by analysis of mRNA and protein levels. Unlike kappaB-responsive promoters, IkappaBbeta promoter-bound p65 inefficiently recruits RNA polymerase II, which stalls at the promoter. We present evidence that this stalling is likely due to the absence of transcription factor IIH engagement, a prerequisite for RNA polymerase II phosphorylation and transcriptional initiation. Differences in the conformation of promoter-bound NF-kappaB may underlie the variation in the ability to engage the basal transcriptional apparatus at the IkappaBbeta and kappaB-responsive promoters. This accounts for the differential expression of IkappaB family members in response to NF-kappaB activation and furthers our understanding of the mechanisms involved in transcription factor activity and IkappaBbeta gene regulation.

Bruton's Tyrosine Kinase Is Involved in p65-mediated Transactivation and Phosphorylation of p65 on Serine 536 during NFκB Activation by Lipopolysaccharide

Bruton's tyrosine kinase (Btk) has recently been shown to participate in the induction of nuclear factor kappaB (NFkappaB)-dependent gene expression by the lipopolysaccharide (LPS) receptor Toll-like receptor-4 (TLR4). In this study we have examined the mechanism whereby Btk participates in this response. Treatment of the murine monocytic cell line Raw264.7 with LFM-A13, a specific Btk inhibitor, blocked LPS-induced NFkappaB-dependent reporter gene expression but not IkappaB alpha degradation. Transient transfection of HEK293 cells with Btk had no effect on NFkappaB-dependent reporter gene expression but strongly promoted transactivation of a reporter gene by a p65-Gal4 fusion protein. IkappaB alpha degradation activated by LPS was intact in macrophages from X-linked immunodeficiency (Xid) mice, which contain inactive Btk. Transfection of cells with a dominant negative form of Btk (BtkK430R) inhibited LPS-driven p65 mediated transactivation. Additionally LFM-A13 impaired phosphorylation of serine 536 on p65 induced by LPS in HEK293-TLR4 cells, and in Xid macrophages this response was impaired. This study therefore reveals a novel function for Btk. It is required for the signaling pathway activated by TLR4, which culminates in phosphorylation of p65 on serine 536 promoting transactivation by NFkappaB.

Stimulus-specific Induction of a Novel Nuclear Factor-κB Regulator, IκB-ζ, via Toll/Interleukin-1 Receptor Is Mediated by mRNA Stabilization

Stimulus-specific Induction of a Novel Nuclear Factor-κB Regulator, IκB-ζ, via Toll/Interleukin-1 Receptor Is Mediated by mRNA Stabilization

Quinazoline-based alpha 1-adrenoceptor antagonists induce prostate cancer cell apoptosis via TGF-beta signalling and I kappa B alpha induction.

Previous studies documented the ability of quinazoline-based α1-adrenoceptor antagonists to induce apoptosis in prostate cancer cells via an α1-adrenoceptor-independent mechanism. In this study we investigated the molecular events initiating this apoptotic effect. Since transforming growth factor-β1 (TGF-β1) mediates prostate epithelial cell apoptosis, we hypothesised that the activation of the TGF-β1 pathway underlies the quinazoline-based apoptotic effect in prostate cancer cells. Treatment of the androgen-independent human prostate cancer cells PC-3 with doxazosin resulted in a strong caspase-3 activation within 24 h, whereas tamsulosin, a sulphonamide-based α1-adrenoceptor antagonist, had no significant apoptotic effect against prostate cancer cells. To identify the molecular components involved in this quinazoline-mediated apoptosis, cDNA microarray analysis of PC-3 prostate cancer cells treated with doxazosin (3 h) was performed. Induced expression of several genes was observed including p21WAF-1 and IκBα (inhibitor of NF-κB alpha). Relative quantitative reverse transcription–polymerase chain reaction analysis revealed induction of several TGF-β1 signalling effectors: Induction of mRNA for Smad4 and the TGF-β1-regulated apoptosis-inducing transcription factor TGF-β1-inducible early gene (TIEG1) was detected within the first 6 h of doxazosin treatment. Upregulation of IκBα at both the mRNA and protein level was also detected after 6 h of treatment. Furthermore, doxazosin resulted in a considerable elevation in Smad4 and TIEG protein expression (6 h). A ‘latent’ increase in TGF-β mRNA expression was detected after 48 h of treatment. These findings suggest that the quinazoline-based doxazosin mediates prostate cancer apoptosis by initially inducing the expression of TGF-β1 signalling effectors and subsequently IκBα. The present study provides an initial insight into the molecular targets of the apoptotic action of quinazolines against prostate cancer cells.

Induction of IκB: atrial natriuretic peptide as a regulator of the NF-κB pathway

Atrial natriuretic peptide (ANP) was shown to possess anti-inflammatory potential due to its potency to inhibit the production of inflammatory mediators, such as TNF-α. The aim of this study was to determine potential effects of ANP on endothelial cells targeted by TNF-α. HUVEC were treated with TNF-α and expression of adhesion molecules was investigated by FACS and RT-PCR. Pre-treatment of cells with ANP (30 min) significantly reduced TNF-α-induced cell surface protein and mRNA expression of E-selectin and ICAM-1, whereas it did not influence VCAM-1. ANP reduced TNF-α-induced NF-κB activity, which was paralleled by a decreased translocation of p65 to nuclei. ANP did not alter TNF-α-induced phosphorylation and degradation of IκB-α, but attenuated degradation of IκB-ε. Moreover, ANP leads to a transcriptional induction of IκB-α. The induction of IκB by ANP is suggested as a novel mechanism for regulating inflammatory signalling in endothelial cells, leading to reduced TNF-α-induced expression of adhesion molecules.

Intracerebroventricular but not intravenous interleukin-1β induces widespread vascular-mediated leukocyte infiltration and immune signal mRNA expression followed by brain-wide glial activation

Interleukin-1β (IL-1β) is a pro-inflammatory cytokine that appears in brain and cerebrospinal fluid following peripheral immune challenges and central infections or injury. We examined the consequences of i.c.v. infusion of IL-1β on mRNA expression of several immune markers and on recruitment of peripheral leukocytes. Awake rats were infused with IL-1β (100 ng/rat) into the lateral ventricle, and 0.5, 2, 4, 8, 12, or 24 h later, animals were killed and their fresh-frozen brains processed for in situ hybridization and immunohistochemistry. Widespread vascular expression of inhibitory factor κBα (IκBα, marker of nuclear factor κBα transcriptional activity) and inducible cyclooxygenase (COX-2) mRNAs at 0.5–2 h was credited to movement of IL-1β along ventricular, subarachnoid, and perivascular pathways to target endothelia that express type 1 IL-1 receptor mRNA. Induction of monocyte chemoattractant protein-1 mRNA and intercellular adhesion molecule-1 (ICAM-1) immunostaining on endothelia began at 0.5–2 h. Leukocytes (neutrophils and monocytes, recognized by morphology and CD45 and ED1 immunostaining) appeared in meninges and blood vessels at 2–4 h and diffusely penetrated the parenchyma at 8–24 h. The leukocytes strongly expressed IL-1β and inducible nitric oxide synthase mRNAs. Beginning at 4–12 h, astrocytes (glial acidic fibrillary protein mRNA and protein and c-fos mRNA) and microglia (ionized calcium-binding adaptor molecule 1 mRNA and protein) showed widespread activation. Other rats received i.v. IL-1β (6 μg/kg). Their brains showed induction of IκBα and COX-2 mRNAs in the vasculature at 2 h but none of the other sequelae. In summary, our data indicate that IL-1β in the cerebrospinal fluid reaches its target receptors on the endothelia via perivascular volume transmission, up-regulates ICAM-1, and triggers a targeted leukocyte emigration and widespread glial activation stimulated perhaps by pro-inflammatory molecules expressed by leukocytes. The dramatic difference between i.c.v. and i.v. routes of administration underscores the potency of IL-1β within the brain to dynamically affect the cellular trafficking component of ‘immune privilege’.

The orphan nuclear receptor RORα is a negative regulator of the inflammatory response

Retinoid-related orphan receptor alpha (ROR alpha) (NR1F1) is a member of the nuclear receptor superfamily whose biological functions are largely unknown. Since staggerer mice, which carry a deletion in the ROR alpha gene, suffer from immune abnormalities, we generated an adenovirus encoding ROR alpha1 to investigate its potential role in control of the inflammatory response. We demonstrated that ROR alpha is expressed in human primary smooth-muscle cells and that ectopic expression of ROR alpha1 inhibits TNFalpha-induced IL-6, IL-8 and COX-2 expression in these cells. ROR alpha1 negatively interferes with the NF-kappaB signalling pathway by reducing p65 translocation as demonstrated by western blotting, immunostaining and electrophoretic mobility shift assays. This action of ROR alpha1 on NF-kappaB is associated with the induction of IkappaB alpha, the major inhibitory protein of the NF-kappaB signalling pathway, whose expression was found to be transcriptionally upregulated by ROR alpha1 via a ROR response element in the IkappaB alpha promoter. Taken together, these data identify ROR alpha1 as a potential target in the treatment of chronic inflammatory diseases, including atherosclerosis and rheumatoid arthritis.

Role of Microglial-Derived Tumor Necrosis Factor in Mediating CD14 Transcription and Nuclear Factor κ B Activity in the Brain during Endotoxemia

Systemic injection of the endotoxin lipopolysaccharide (LPS) upregulates the gene encoding CD14 early in the circumventricular organs (CVOs) and later in the brain parenchyma. The present study tested the hypothesis that the parenchymal production of the proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) by microglial cells is responsible for triggering CD14 transcription in an autocrine/paracrine loop-like manner. In a first set of experiments, Sprague Dawley rats were killed 1, 3, 6, and 12 hr after an intracerebroventricular administration of recombinant rat TNF-alpha or vehicle solution. Second, anti-rat TNF-alpha-neutralizing antibody or vehicle solution was administrated into the lateral ventricle 10 hr before an intraperitoneal injection of LPS. Central administration of the cytokine caused a strong induction of IkappaBalpha, TNF-alpha, and CD14 mRNA in parenchymal microglial cells. The hybridization signal for these transcripts was localized to the edge of the ventricles and the site of infusion. The time-related expression of each mRNA suggested that TNF-alpha has the ability to trigger its own production followed by the transcription of the LPS receptor; the signal for IkappaBalpha, TNF-alpha, and CD14 peaked at 1, 3, and 6 hr, respectively. The genes encoding TNF-alpha and mCD14 were also induced in the CVOs and within microglial cells across the brain parenchyma in response to intraperitoneal LPS administration. This induction in parenchymal cells of the brain was prevented in animals that received the anti-TNF-antisera intracerebroventricularly 10 hr before the systemic treatment with the endotoxin. The present data provide the evidence that microglial-derived TNF-alpha is responsible for the production of the LPS receptor CD14 during endotoxemia. This autocrine/paracrine stimulatory loop may be of great importance in controlling the inflammatory events that take place in the CNS during innate immune response as well as under pathological conditions.

TGF-β1 Inhibits NF-κB Activity through Induction of IκB-α Expression in Human Salivary Gland Cells: A Possible Mechanism of Growth Suppression by TGF-β1

Transforming growth factor (TGF)-β is the prototype of a large superfamily of signaling molecules involved in the inhibition of proliferation of multiple epithelial cell types. Although accumulated evidence indicates the mechanisms of the antimitogenic effect of TGF-β in a variety of cell types, the signal transduction mechanism underlying the regulation of NF-κB transcription factor by TGF-β is largely unknown. Because NF-κB is not only involved in inflammatory responses but also mediates cell growth, we have investigated the effect of TGF-β1 on the activity of NF-κB and the role of the inhibitory IκB-α protein in the growth of the human salivary gland cell clones NS-SV-AC, HSGc, and cl-1. NF-κB, which is usually maintained in an inactive state by protein–protein interaction with IκB, was found to be constitutively active in salivary gland cell lines. Upon treatment of cell clones with TGF-β1, the NF-κB activity in NS-SV-AC and HSGc, but not in cl-1, which lacks the expression of TGF-β type II receptor, was suppressed. In NS-SV-AC and HSGc, this inhibition was mediated by the induction of IκB-α at the mRNA and protein levels. The blocking of NF-κB subunit with a specific antisense oligonucleotide reduced the growth rate of all of the cell clones, including cl-1. Introduction of a mutated form of IκB-α cDNA into NS-SV-AC suppressed the growth rate of this cell clone. These results indicate that TGF-β1 downregulates NF-κB activity through the induction of IκB-α expression in human salivary gland cells and that inhibition of NF-κB activity suppresses the growth rate of these cells.

Heat shock activates the I-κBα promoter and increases I-κBα mRNA expression

Recent data indicate that the heat shock response inhibits nuclear translocation of the proinflammatory transcription factor NF-κB. Under basal conditions NF-κB is retained in the cytoplasm by an inhibitory protein called I-κB which exists as two major isoforms: I-κBα and I-κBβ. Induction of the heat shock response in BEAS-2B cells, a human cell line representative of bronchial epithelium, increased expression of I-κBα mRNA in a time-dependent manner. Coincubation with actinomycin-D inhibited heat shock-mediated expression of I-KBα mRNA. Transient transfection assays with a plasmid containing the reporter gene firefly luciferase, under the control of the human I-κBα promoter, demonstrated that heat shock activated the I-κBα promoter. Heat shock-mediated induction of I-κBα was associated with inhibition of NF-κB activation. We conclude that heat shock increases I-κBα mRNA expression in BEAS-2B cells by activating the I-κBα promoter, and propose that heat shock-mediated up-regulation of I-κBα is a potential mechanism by which the heat shock response inhibits proinflammatory responses in lung cells.