Effects Of IL-1beta Research Articles

Intracellular degradation of insulin and crinophagy are maintained by nitric oxide and cyclo‐oxygenase 2 activity in isolated pancreatic islets

Pancreatic beta-cells require an optimal insulin content to allow instantaneous secretion of insulin. This is maintained by insulin biosynthesis and intracellular degradation of insulin. Degradation may be effected by crinophagy, i.e. the fusion of secretory granules with lysosomes. IL-1beta (interleukin 1beta) induces distinct changes of beta-cell lysosomes. To study the mechanisms for intracellular insulin degradation and crinophagy, isolated mouse pancreatic islets were exposed to IL-1beta and known pathways for IL-1beta actions were blocked. Intracellular insulin degradation was determined by following the fate of radioactively labelled insulin. Crinophagy was studied by ultrastructural analysis. The effects of blocking pathways for IL-1beta were monitored by measurements of nitrite and PGE(2) (prostaglandin E(2)). IL-1beta caused an enhancement of islet intracellular insulin degradation and an increase in the lysosomal incorporation of beta-cell secretory granules. The effects of IL-1beta were abolished by aminoguanidine, a selective inhibitor of inducible NOS (nitric oxide synthase), or by rofecoxib, a specific inhibitor of COX-2 (cyclo-oxygenase 2). In the absence of IL-1beta, nitroarginine, which is a selective inhibitor of constitutive NOS, caused a decrease in intracellular degradation of insulin in parallel with a decreased production of NO and PGE(2) by the islets. The correlation between the enhanced intracellular insulin degradation and lysosomal changes caused by IL-1beta suggests that insulin degradation may be effected by crinophagy. Under physiological conditions, significant beta-cell degradation of insulin may depend on the activity of COX-2, possibly stimulated by endogenous NO.

Interleukin-1β Enhances GABAA Receptor Cell-surface Expression by a Phosphatidylinositol 3-Kinase/Akt Pathway: RELEVANCE TO SEPSIS-ASSOCIATED ENCEPHALOPATHY

Sepsis-associated encephalopathy (SAE) is a frequent but poorly understood neurological complication in sepsis that negatively influences survival. Here we present clinical and experimental evidence that this brain dysfunction may be related to altered neurotransmission produced by inflammatory mediators. Compared with septic patients, SAE patients had higher interleukin-1beta (IL-1beta) plasma levels; interestingly, these levels decreased once the encephalopathy was resolved. A putative IL-1beta effect on type A gamma-aminobutyric acid receptors (GABA(A)Rs), which mediate fast synaptic transmission in most cerebral inhibitory synapses in mammals, was investigated in cultured hippocampal neurons and in Xenopus oocytes expressing native or foreign rat brain GABA(A)Rs, respectively. Confocal images in both cell types revealed that IL-1beta increases recruitment of GABA(A)Rs to the cell surface. Moreover, brief applications of IL-1beta to voltage-clamped oocytes yielded a delayed potentiation of the GABA-elicited chloride currents (I(GABA)); this effect was suppressed by IL-1ra, the natural IL-1 receptor (IL-1RI) antagonist. Western blot analysis combined with I(GABA) recording and confocal images of GABA(A) Rs in oocytes showed that IL-1beta stimulates the IL-1RI-dependent phosphatidylinositol 3-kinase activation and the consequent facilitation of phospho-Akt-mediated insertion of GABA(A)Rs into the cell surface. The interruption of this signaling pathway by specific phosphatidylinositol 3-kinase or Akt inhibitors suppresses the cytokine-mediated effects on GABA(A)R, whereas activation of the conditionally active form of Akt1 (myr-Akt1.ER*) with 4-hydroxytamoxifen reproduces the effects. These findings point to a previously unrecognized signaling pathway that connects IL-1beta with increased "GABAergic tone." We propose that through this mechanism IL-1beta might alter synaptic strength at central GABAergic synapses and so contribute to the cognitive dysfunction observed in SAE.

Endogenous Interleukin (IL)–1α and IL‐1β Are Crucial for Host Defense against Disseminated Candidiasis

Interleukin (IL)-1 alpha and IL-1 beta are protective proinflammatory cytokines involved in host defense against Candida albicans. It is, however, unknown whether they provide protection through similar mechanisms. We investigated the effect of endogenous IL-1 alpha and IL-1 beta on disseminated C. albicans infection. Mice deficient in the genes encoding IL-1 alpha (IL-1 alpha-/-), IL-1 beta (IL-1 beta-/-), or both molecules (IL-1 alpha-/- beta-/-) were used. Survival and C. albicans outgrowth in the kidneys was assessed after intravenous injection of C. albicans. Both mortality and C. albicans outgrowth in the kidneys were significantly increased in IL-1 alpha-/- and IL-1 beta-/- mice, compared with those in control mice, with the IL-1 alpha-/- beta-/- mice being most susceptible to disseminated candidiasis. The host defense mechanisms triggered by IL-1 alpha and IL-1 beta differed from one another. IL-1 beta-/- mice showed decreased recruitment of granulocytes in response to an intraperitoneal C. albicans challenge, and generation of superoxide production was diminished in IL-1 beta-/- granulocytes. IL-1 alpha-/- mice had a reduced capacity to damage C. albicans pseudohyphae. Protective type 1 responses were deficient in both IL-1 alpha-/- and IL-1 beta-/- mice, as assessed by production of interferon-gamma by splenocytes in response to heat-killed C. albicans. Although IL-1 alpha and IL-1 beta have differential effects on the various arms of host defense, both cytokines are essential for mounting a protective host response against invasive C. albicans infection.

Synovial membrane cytokine expression is predictive of joint damage progression in rheumatoid arthritis: A two‐year prospective study (the DAMAGE study cohort)

The primary aim of this prospective 2-year study was to explain the wide variability in joint damage progression in patients with rheumatoid arthritis (RA) from measures of pathologic changes in the synovial membrane. Patients underwent clinical measurements and joint damage assessments by magnetic resonance imaging (MRI) and radiography at enrollment and at year 2. Synovial membrane was obtained by knee biopsy and assessed histologically by hematoxylin and eosin staining. Interleukin-1beta (IL-1beta), IL-10, IL-16, IL-17, RANKL, tumor necrosis factor alpha (TNFalpha), and interferon-gamma (IFNgamma) messenger RNA (mRNA) expression was determined by quantitative reverse transcription-polymerase chain reaction. The relationship of synovial measurements to joint damage progression was determined by multivariate analysis. Sixty patients were enrolled. Histologic features had no relationship to damage progression. Multivariate analysis by several different methods consistently demonstrated that synovial membrane mRNA levels of IL-1beta, TNFalpha, IL-17, and IL-10 were predictive of damage progression. IL-17 was synergistic with TNFalpha. TNFalpha and IL-17 effects were most pronounced with shorter disease duration, and IL-1beta effects were most pronounced with longer disease duration. IFNgamma was protective. These factors explained 57% of the MRI joint damage progression over 2 years. We have demonstrated for the first time in a prospective study that synovial membrane cytokine mRNA expression is predictive of joint damage progression in RA. The findings for IL-1beta and TNFalpha are consistent with results of previous clinical research, but the protective role of IFNgamma, the differing effects of disease duration, and IL-17-cytokine interactions had only been demonstrated previously by animal and in vitro research. These findings explain some of the variability of joint damage in RA and identify new targets for therapy.

Regulation of the Human Oxytocin Receptor by Nuclear Factor-κB and CCAAT/Enhancer-Binding Protein-β

Increased myometrial sensitivity to oxytocin at term is mediated through increased oxytocin receptor (OTR) expression. OTR promoter contains putative transcription factor-binding sites for activating protein-1 (AP-1), CCAAT/enhancer-binding protein (C/EBP), and nuclear factor-kappaB (NF-kappaB), which may be activated by IL-1beta, whose concentrations increase with labor. The objective of this study was to examine the effect of IL-1beta on OTR expression and the roles of AP-1, C/EBP, and NF-kappaB in OTR promoter function. IL-1beta induces an increase in OTR mRNA concentrations and OTR ligand binding in myometrial cells, which is maximal at 4 h and decreased after 20 h. IL-1beta activates the transcription factors AP-1 C/EBPbeta, and NF-kappaB. Using computer-based analysis and EMSA studies, we have identified three AP-1, nine C/EBP, and three NF-kappaB DNA-binding sites in the OTR promoter. In transient transfection studies, OTR promoter activity was increased by C/EBPbeta and NF-kappaB, but not by AP-1. C/EBPbeta and NF-kappaB together had a synergistic action in the induction of OTR promoter activity. Site-directed mutagenesis of each individual C/EBP and NF-kappaB site had no effect on the ability of C/EBPbeta, NF-kappaB, or their combination to activate OTR promoter. However, mutation of both NF-kappaB sites inhibited promoter activation by NF-kappaB alone, but not that by the combination of C/EBPbeta and NF-kappaB. Deletion studies showed that a region between -851 and -656 of the OTR confers responsiveness to the combination of C/EBPbeta and NF-kappaB. IL-1beta has a biphasic effect on OTR expression in myometrial cells, and C/EBP and NF-kappaB play synergistic roles in OTR promoter activation.

Differential expression of VEGF‐A and angiopoietins in cartilage tumors and regulation by interleukin‐1β

Vascular endothelial growth factor (VEGF)-A and angiopoietin (Ang)-1 and Ang-2 are key factors in angiogenic signaling. In this study the expression of these factors was identified in cartilage tumors. As interleukin (IL)-1beta has been found to be an indispensable factor in angiogenic signaling, we further analyzed the effect of IL-1beta on the expression of VEGF-A, Ang-1, and Ang-2 using a previously established cell culture model. Surgical specimens of enchondromas, conventional chondrosarcomas, and dedifferentiated chondrosarcomas were obtained from 72 patients. VEGF-A, Ang-1, and Ang-2 mRNA expression was detected by conventional and quantitative reverse transcription polymerase chain reaction (PCR). VEGF-A expression was also detected by immunohistochemistry or Western blot. Differential expression of VEGF-A, Ang-1, and Ang-2 was clearly demonstrated in cartilage tumors. VEGF-A expression was positively correlated with the tumor type. Higher VEGF-A expression levels were detected in conventional chondrosarcomas Grades II and III (using a 3-tier grading system) than in dedifferentiated chondrosarcomas (P < .05). A typical pattern of VEGF-A isoforms was identified, including VEGF(121), VEGF(145), VEGF(165), and VEGF(189). Ang-1 presented as a low-level transcript with slightly elevated levels in chondrosarcomas (P < .05). Highly variable Ang-2 expression levels were detected in solitary cases of conventional chondrosarcomas. IL-1beta regulated VEGF-A and Ang-1 expressions in a dose-dependent manner. Whereas low IL-1beta concentrations increased VEGF-A and Ang-1 transcription, high IL-1beta concentrations had the opposite effect. IL-1beta did not activate Ang-2 expression. Angiogenic signaling in cartilage tumors is variable and at least partly regulable by IL-1beta. The findings are of therapeutic relevance, either as a desired effect or a side effect in medical treatment.

Cytokine-Induced Proapoptotic Gene Expression in Insulin-Producing Cells Is Related to Rapid, Sustained, and Nonoscillatory Nuclear Factor-κB Activation

Cytokines, such as IL-1beta and TNF-alpha, contribute to pancreatic beta-cell death in type 1 diabetes mellitus. The transcription factor nuclear factor-kappaB (NF-kappaB) mediates cytokine-induced beta-cell apoptosis. Paradoxically, NF-kappaB has mostly antiapoptotic effects in other cell types. The cellular actions of NF-kappaB depend on the cell type, the nature and duration of the stimulus, the periodicity, and the degree of activity of the particular dimers involved. To clarify the reasons behind the proapoptotic effects of NF-kappaB in pancreatic beta-cells, we compared the pattern of cytokine-induced NF-kappaB activation between rat insulin-producing cells (INS-1E cells) and fibroblasts (208F cells). NF-kappaB activation was induced in INS-1E cells and in 208F cells after exposure to cytokines, but apoptosis was induced only in INS-1E cells, with a more pronounced proapoptotic effect of IL-1beta than of TNF-alpha. NF-kappaB activation in IL-1beta-exposed INS-1E cells was earlier and more marked as compared with TNF-alpha-exposed INS-1E cells or IL-1beta-exposed 208F cells. Both cytokines induced a prolonged (up to 48 h) and stable NF-kappaB activation in INS-1E cells, whereas IL-1beta induced an oscillatory NF-kappaB activation in 208F cells. p65/p65 and p65/p50 were the predominant NF-kappaB dimers in IL-1beta-exposed INS-1E cells and 208F cells, respectively. IL-1beta induced a differential usage of cis-elements in the inducible nitric oxide synthase promoter region in the two cell-lines and an increase in ERK1/2 activity in INS-1E cells but not in 208F cells. Cytokine-induced expression of IkappaB isoforms and other NF-kappaB target genes (Fas, MCP-1, and inducible nitric oxide synthase) was severalfold higher in INS-1E cells than in 208F cells. These results suggest that cytokine-induced NF-kappaB activation in insulin-producing cells is more rapid, marked, and sustained than in fibroblasts, which correlates with a more pronounced activation of downstream genes and a proapoptotic outcome.

The Proinflammatory Cytokines Interleukin-1beta and Tumor Necrosis Factor-Alpha Activate Serotonin Transporters

Proinflammatory cytokines and serotonergic homeostasis have both been implicated in the pathophysiology of major psychiatric disorders. We have demonstrated that activation of p38 mitogen-activated protein kinase (MAPK) induces a catalytic activation of the serotonin transporter (SERT) arising from a reduction in the SERT Km for 5-hydroxytryptamine (5-HT). As inflammatory cytokines can activate p38 MAPK, we hypothesized that they might also activate neuronal SERT. Indeed, Interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) stimulated serotonin uptake in both the rat embryonic raphe cell line, RN46A, and in mouse midbrain and striatal synaptosomes. In RN46A cells, IL-1beta stimulated 5-HT uptake in a dose- and time-dependent manner, peaking in 20 min at 100 ng/ml. This was abolished by IL-1ra (20 ng/ml), an antagonist of the IL-1 receptor, and by SB203580 (5 microM), a p38 MAPK inhibitor. TNF-alpha also dose- and time-dependently stimulated 5-HT uptake that was only partially blocked by SB203580. Western blots showed that IL-1beta and TNF-alpha activated p38 MAPK, in an SB203580-sensitive manner. IL-1beta induced an SB203580-sensitive decrease in 5-HT Km with no significant change in Vmax. In contrast, TNF-alpha stimulation decreased 5-HT Km and increased SERT Vmax. SB203580 selectively blocked the TNF-alpha-induced change in SERT Km. In mouse midbrain and striatal synaptosomes, maximal stimulatory effects on 5-HT uptake occurred at lower concentrations (IL-1beta, 10 ng/ml; TNF-alpha, 20 ng/ml), and over shorter incubation times (10 min). As with RN46A cells, the effects of IL-1beta and TNF-alpha were completely (IL-1beta) or partially (TNF-alpha) blocked by SB203580. These results provide the first evidence that proinflammatory cytokines can acutely regulate neuronal SERT activity via p38 MAPK-linked pathways.

Inhibition of pyocyanin-potentiated IL-8 release by steroids in bronchial epithelial cells

Airway epithelial cells are the first targets of environmental stimuli and local cytokines. Pyocyanin-induced synergism with interleukin (IL)-1 or tumour necrosis factor (TNF) in triggering IL-8 release has been documented previously. In this study, IL-8 mRNA and protein expression were examined in cultured human bronchial epithelial cells (BEAS-2B) stimulated with pyocyanin alone, and in combination with IL-1beta or phorbol 12,13-dibutyrate (PDBu) in the absence and presence of a group of glucocorticoids. IL-8 mRNA was measured by RT-PCR, and IL-8 protein by ELISA (cell supernatants). Pyocyanin alone produced no increase in IL-8 mRNA and release. However, pyocyanin upregulated the stimulatory effect of IL-1beta or PDBu on the release of IL-8 in a dose-dependent manner. The stimulatory effect of pyocyanin on the IL-1beta- or PDBu-stimulated IL-8 release was reduced in the presence of dexamethasone, budesonide, and fluticasone. Budesonide and fluticasone were 10-fold more potent than dexamethasone. The protein kinase C (PKC) inhibitor, Go6976, also significantly reduced the stimulatory effect of pyocyanin on IL-1beta, and PDBu increased IL-8 release. In conclusion, this study shows that PKC signal pathway seems to be involved in the pyocyanin-mediated upregulation of the IL-1beta and PDBu-induced IL-8 release in BEAS-2B cells. These findings suggest that a vicious cycle perpetuating inflammation may exist in the biologic milieu of bronchiectatic patients infected with Pseudomonas aeruginosa due to the production of pyocyanin. The priming action of pyocyanin appears to be blocked by glucocorticoids, thus providing in vitro data in support of the clinical efficacy of inhaled glucocorticoids as anti-inflammatory drugs.

Effects of IL-1 beta on RT1-A/RT1-DM at the maternal-fetal interface during pregnancy in rats

Interleukin-1 (IL-1beta) beta and major histocompatibility complex (MHC) play an important role during pregnancy. Expression of non-classical class MHC II RT1-DM antigen and classical class MHC I RT1-A antigen induced by IL-1beta was examined by Northern blotting, Western blotting and immunohistochemistry. IL-1beta treatment significantly increased the expression of RT1-A and RT1-DM in early and mid pregnancy. In late pregnancy, expression of RT1-DM significantly increased in uteri and decreased in placenta. Immunohistochemical studies indicated that, in early pregnancy, RT1-DM protein mainly localized to luminal and glandular uterine epithelium, and RT1-A was present in deciduas basalis, outer layer of luminal epithelium and glandular epithelium. During mid and late pregnancy, RT1-DM was present in maternal blood vessels and syncytiotrophoblast of labyrinthine zone, and RT1-A was present in maternal blood vessels and trophoblastic epithelium of the labyrinthine layers. These findings show that exogenous IL-1beta affects expression of RT1-DM and RT1-A and does not affect the localization of corresponding molecules during pregnancy.

The influence of interleukin-1β on γ-glutamyl transpepidase activity in rat hippocampus

Brain infections as well as peripheral challenges to the immune system lead to an increased production of interleukin-1beta (IL-1beta), a cytokine involved in leukocyte-mediated breakdown of the blood-brain barrier. The effects of IL-1beta have been reported to depend on whether the route of administration is systemic or intracerebral. Using 50-day-old male rats, we compared the effects of IL-1beta on brain gamma-glutamyl transpeptidase (GGT; an enzymatic marker of brain capillary endothelium) at 2, 24 and 96 h after either an intravenous (i.v.) injection of 5 microg IL-1beta or an intracerebroventricular (i.c.v. - lateral ventricle) infusion of 50 ng IL-1beta. When the i.v. route was used, the GGT activity underwent small but significant changes; decreasing in the hippocampus 2 h after the i.v. injection, increasing 24 h later and returning to control levels at 96 h. No significant changes in the hippocampal GGT activity were observed at 2 and 24 h following the i.c.v. infusion. The GGT activity in the hypothalamus remained unchanged regardless of the route of IL-1beta administrations. Similar changes in GGT activity were revealed histochemically. The labeling was found mainly in the capillary bed, the changes being most evident in the hippocampal stratum radiatum and stratum lacunosum-moleculare. A transient increase in GGT activity at 24 h, together with a less sharp delineation of GGT-stained vessels, may reflect IL-1beta induced increased turnover of glutathione and/or oxidative stress, that may in turn, be related to altered permeability of the blood-brain barrier in some neurological and mental disorders, including schizophrenia.

In Vitro Assessment of the Effect of Interleukin-1.BETA. on Angiogenic Potential of Bone Marrow Cells

Therapeutic angiogenesis for ischemic diseases has been successfully induced by the implantation of autologous bone marrow cells (BMCs). It is understood that interleukin (IL)-1beta increases remarkably in ischemic tissue and has particular effects on angiogenesis. Thus, it is important to clarify how IL-1beta would effect BMCs survival and angiogenic potential. The effect of IL-1beta on BMCs survival, adhesion, and endothelial differentiation, as well as the production of angiogenic growth factors, was investigated using an in vitro assessment approach. BMCs were harvested from Zucker obese rats and cultured at a density of 3x10(6) cells/ml with 5 ng/ml IL-1 beta (IL-1beta group) or without IL-1 beta (control group). Survival and adhesion of BMCs were significantly increased in the IL-1beta group than in the control group after 1, 3, and 7 days of culture (p<0.01). The release of vascular endothelial growth factor in supernatant was also significantly higher in the IL-1beta group than in the control group after 3 and 7 days of culture (p<0.01). Furthermore, the number of differentiated endothelial cells derived from BMCs was significantly higher in the IL-1beta group than in the control group after 7 days of culture (p<0.01). These results suggest that IL-1beta has a positive effect on the angiogenic potential of BMCs in vitro.

C‐Jun NH2‐terminal kinase mediates interleukin‐1β‐induced inhibition of lacrimal gland secretion

Sjögren's syndrome, an inflammatory disease affecting the lacrimal and salivary glands, is the leading cause of aqueous tear-deficient type of dry eye. We previously showed that interleukin-1beta (IL-1beta) protein is up regulated in the lacrimal gland of a murine model of Sjögren's syndrome and that exogenous addition of this cytokine inhibits neurotransmitter release and lacrimal gland protein secretion. In the present study we investigated the role of c-Jun NH2-terminal kinase (JNK) in IL-1beta-mediated inhibition of lacrimal gland secretion and tear production. In vitro, IL-1beta induced a time-dependent activation of JNK with a maximum 7.5-fold at 30 min. SP600125, a JNK inhibitor, inhibited, in a concentration-dependent manner, IL-1beta-induced activation of JNK with a maximum of 87% at 10(-4) m. In vivo, IL-1beta stimulated JNK and the expression of the inducible isoform of nitric oxide synthase (iNOS). IL-1beta inhibited high KCl and adrenergic agonist induced protein secretion by 85% and 66%, respectively. SP600125 alleviated the inhibitory effect of IL-1beta on KCl- and agonist-induced protein secretion by 79% and 47%, respectively, and completely blocked the expression of iNOS. Treatment for 7 days with SP600125 increased tear production in a murine model of Sjögren's syndrome dry eye. We conclude that JNK plays a pivotal role in IL-1beta-mediated inhibition of lacrimal gland secretion and subsequent dry eye.

Nitric oxide down‐regulates the expression of the catalytic NADPH oxidase subunit Nox1 in rat renal mesangial cells

Glomerular mesangial cells can produce high amounts of nitric oxide (NO) and reactive oxygen species (ROS). Here we analyzed the impact of NO on the ROS-generating system, particularly on the NADPH oxidase Nox1. Nox1 mRNA and protein levels were markedly decreased by treatment of mesangial cells with the NO-releasing compound DETA-NO in a concentration- and time-dependent fashion. By altering the cGMP signaling system with different inhibitors or activators, we revealed that the effect of NO on Nox1 expression is at least in part mediated by cGMP. Analysis of a reporter construct comprising the 2547 bp of the nox1 promoter region revealed that a stimulatory effect of IL-1beta on nox1 transcription is counteracted by an inhibitory effect of IL-1beta-evoked endogenous NO formation. Moreover, pretreatment of mesangial cells with DETA-NO attenuated platelet-derived growth factor (PDGF)-BB or serum stimulated production of superoxide as assessed by real-time EPR spectroscopy and dichlorofluorescein formation. Transfection of mesangial cells with siRNAs directed against Nox1 and Nox4 revealed that inhibition of Nox1, but not Nox4 expression, is responsible for the reduced ROS formation by NO. Obviously, there exists a fine-tuned crosstalk between NO and ROS generating systems in the course of inflammatory diseases.

Interleukin‐1β downregulates the L‐type Ca2+ channel activity by depressing the expression of channel protein in cortical neurons

Interleukin-1beta (IL-1beta), a proinflammatory cytokine, has been involved in various diseases of the central nervous system (CNS). Due to the diverse, "contradictory" effects of IL-1beta on neurons during insults to the brain, the mechanisms underlying these effects have not been elucidated. Calcium influx through the L-type Ca2+ channels (LCCs) is believed to play a critical role in the cascade of biochemical events leading to neuron death in these pathophysiological conditions. So far, the mechanism of the interaction of IL-1beta and LCCs in the initiation and progression of these diseases is unclear. In this study, we investigate systemically the effects of IL-1beta on the LCCs current, which are believed to be implicated in the cascade of biochemical events leading to neuron death in neuropathological conditions. Using patch clamp, we observe that IL-1beta treatment (10 ng/ml, 24 h) suppresses LCC currents by approximately 38%, which made up half of the whole-cell Ca2+ current determined by nifedipine. IL-1beta does not alter the characteristics of single LCC including current amplitude, open probability, and conductance, but decreases the number of the functioning channel by 40%. Moreover, immunoblot assay exhibits that IL-1beta reduces the expression of LCC proteins by 38 approximately 42% in both whole neuron and plasma membrane fraction, and demonstrates that IL-1beta downregulates the LCC activity via the reduction of LCC density. According to early research pretreatments longer than 12 h may play a crucial role in the neuroprotective effects of IL-1beta, our findings may establish an explanation for the protective effects of this interleukin on neurons in the late stage of injury, and could raise a new issue to clinical treatment for insults to brain.

Die Bedeutung der Zytokine in der posttraumatischen Entzündungsreaktion

Alterations in the immune response after multiple trauma, posttraumatic sepsis and surgery are recognized as physiological reactions of the organism to restore homeostasis. The level of these immunological changes correlates with the degree of tissue damage as well as with the severity of haemorrhage and ischaemia. Cytokines are known to be integral components of this immune response. The local release of pro- and antiinflammatory cytokines after severe trauma indicates their potential to induce systemic immunological alterations. It appears that the balance or imbalance of these different cytokines partly controls the clinical course in these patients. Overproduction of either proinflammatory cytokines or antiinflammatory mediators may result in organ dysfunction. Whereas predominance of the proinflammatory response leads to the systemic inflammatory response syndrome (SIRS), the antiinflammatory reaction may result in immune suppression with an enhanced risk of infectious complications. Systemic inflammation, as well as immune suppression, are thought to play a decisive role in the development of multiple organ dysfunction syndrome (MODS). The major proinflammatory cytokines involved in the response to trauma and surgery include tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6 and IL-8. These cytokines, which are predominantly produced by monocytes and macrophages, mediate a variety of frequently overlapping effects, and their actions can be additive. TNF-alpha and IL-1beta are early regulators of the immune response and both induce the release of secondary cytokines, such as IL-6 and IL-8. IL-10 is an antiinflammatory cytokine which reduces the synthesis of proinflammatory mediators. Other important antiinflammatory mediators are soluble TNF receptors and the IL-1 receptor antagonist, which interfere with the effects of TNF-alpha and IL-1beta.Early evaluation of the prognosis of polytraumatized patients and assessment of their clinical status is known to be difficult. Therefore, in several clinical studies, cytokine levels during the posttraumatic course have been determined with the aim of finding predictive markers of patient outcome. The purpose of this review was to highlight our current knowledge on the interaction of posttraumatic immune reactivity and the development of complications. A better understanding of these mechanisms might lead to the introduction of preventive and therapeutic strategies into clinical practice.

Upregulation of hepcidin by interleukin-1β in human hepatoma cell lines

Anemia of chronic disease (ACD) is commonly observed in chronic inflammation, although its pathogenesis is poorly understood. Hepcidin is thought to be a key regulator in iron metabolism and has been implicated in ACD. Although the induction of hepcidin by an inflammatory cytokine interleukin-6 (IL-6) seems to have been confirmed, it is still controversial whether interleukin-1beta (IL-1beta), also known as an inflammatory cytokine, regulates hepcidin expression. We demonstrated that hepcidin mRNA was upregulated by IL-1beta in human hepatoma-derived HuH-7 cells, particularly at low concentrations of IL-1beta, while high concentrations of IL-6 were needed for the upregulation of hepcidin mRNA. Therefore, IL-1beta might be more important for the upregulation of hepcidin in physiological conditions than IL-6. Although IL-1beta induces IL-6 production in hepatocytes, our data indicate that the effect of IL-1beta on hepcidin expression is independent from that of IL-6. In conclusion, IL-1beta might have an important role in ACD.

IL-1β Treatment Does not Co-ordinately Up-regulate mPGES-1 and COX-2 mRNA Expression, but Results in Higher Degree of Cellular and Intracellular Co-localization of their Immunoreactive Proteins in Human Placenta Trophoblast Cells

PGE2 is involved in initiation and progression of labor in many species. Biosynthesis of PGE2 is mediated by cyclooxygenases (COX) and prostaglandin E synthases (PGES). mPGES-1 and COX-2 form an inducible pathway for PGE2 production in many cell systems. In this study we investigated whether mPGES-1 is involved in cytokine induced PGE2 biosynthesis in human trophoblast cells. We have evaluated the cellular and intracellular co-localization of mPGES-1 and COX-2, as well as cPGES and COX-1 in human trophoblast cells by dual immunofluorescent staining. The effect of IL-1beta on mPGES-1 and COX-2 co-localization, such as would occur with infection, and the regulatory effects of pro-inflammatory cytokines IL-1beta and TNF-alpha on transcriptional activity of mPGES-1 and COX-2 in these cells were also studied. We found that in cultured unstimulated trophoblasts, some cells expressed predominantly either mPGES-1 or COX-2, though there were cells co-expressing both enzymes. With IL-1beta treatment, mPGES-1 and COX-2 became more consistently co-localized. mPGES-1 was not transcriptionally co-induced with COX-2 by the cytokine treatment. We conclude that mPGES-1 is not involved in the inducible COX-2 mediated pathway for PGE2 biosynthesis at the transcriptional level, however, the treatment with IL-1beta results in a higher degree of co-ordination of the mPGES-1 and COX-2 protein immunolocalization, eliciting PGE2 synthesis.

TNF-α and IL-1β Increase Pericyte/Endothelial Cell Co-Culture Permeability

Pericytes (PC) have a unique synergistic relationship with microvascular endothelial cells (MVEC) in the regulation of capillary permeability. This study investigates the effect of TNF-alpha, IL-1beta, and IL-6 on the microvasculature by measuring changes in PC contractility, and also, albumin permeability across MVEC/PC co-cultures. Semi-permeable inserts were plated first with rat lung MVEC and then PCs (on the fourth day) at a ratio of 10:1 MVEC/PC. On day 5, 50 ng/ml of TNF-alpha, IL-1beta, and IL-6 were added with or without a secretory phospholipase A(2)-IIA (sPLA(2)-IIA) inhibitor for 24 h. After treatments, albumin clearances were quantified. For measuring contractility, PCs were cultured on collagen matrices and exposed for 24 h to TNF-alpha, IL-1beta, and IL-6 at 1 ng/ml, 10 ng/ml, and 50 ng/ml with/without inhibitors for sPLA(2)-IIA, phospholipase A(2) (PLA(2)), and cyclooxygenase-II (COX-II). After treatments, the surface area of the collagen disks was digitally quantified. TNF-alpha and IL-1beta significantly increased albumin clearance in MVEC/PC co-cultures (P < 0.05) and induced dose-dependent relaxation of PCs (P < 0.05). PC relaxation was completely attenuated with the sPLA(2)-IIA and pLA(2) inhibitors; the COX-II inhibitor provided partial blockade. IL-6 had no effect on PC contractility or permeability. TNF-alpha and IL-1beta directly increased microvascular permeability in co-cultures. They also induced relaxation of PCs through a sPLA(2)-IIA dependent mechanism. Interestingly, IL-6 had no effect, although its presence in high levels has been demonstrated in inflamed lungs. These findings may help elucidate the significance of PC in regulating the capillary response to various pro-inflammatory cytokines.

Pro- and anti-inflammatory cytokines regulate the ERK pathway: Implication of the timing for the activation of microglial cells

Pro-inflammatory molecules induce glial activation and the release of potentially detrimental factors capable of generating oxidative damage, such as nitric oxide (NO) and superoxide anion (O2.-). Activated glial cells (astrocytes and microglia) are associated to the inflammatory process in neurodegenerative diseases. A strong inflammatory response could escape endogenous control becoming toxic to neurons and contributing to the course of the disease. We evaluated in a hippocampal cells-microglia co-culture model, if the pro-inflammatory condition induced by lipopolysaccharide + interferon-gamma (LPS+IFN-gamma) promoted damage directly or if damage was secondary to glial activation. In addition, we explored the effect of the anti-inflammatory cytokine transforming growth factor-beta1 (TGF-beta1), and pro-inflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) on the regulation of the inflammatory response of microglia. We found that LPS+IFN-gamma-induced damage on hippocampal cultures was dependent on the presence of microglial cells. In hippocampal cultures exposed to LPS+IFN-gamma, TGF-beta1 was induced whereas in microglial cell cultures LPS+IFN-gamma induced the secretion of IL-1beta. TGF-beta1 and IL-1beta but not TNF-alpha decreased the NO production by 70-90%. PD98059, an inhibitor of MAP kinase (MEK), reduced the IFN-gamma-induced NO production by 40%. TGF-beta and IL-1beta reduced the IFN-gamma induced phosphorylation of ERK1,2 by 60% and 40%, respectively. However, the effect of IL-1beta was observed at 30 min and that of TGF-beta1 only after 24 h of exposure. We propose that acting with different timing, TGF-beta1 and IL-1beta can modulate the extracellular signal-regulated kinase ERK1,2, as a common element for different transduction pathways, regulating the amplitude and duration of glial activation in response to LPS+IFN-gamma. Cross-talk among brain cells may be key for the understanding of inflammatory mechanisms involved in pathogenesis of neurodegenerative diseases.