Produce Interleukin-6 In Response Research Articles

Hyperthermia alters interleukin-6 production in response to lipopolysaccharide via endoplasmic reticulum stress in bovine endometrial cells.

In the postpartum period, cows experience the uterine bacterial infection and develop the endometritis. To eliminate bacteria and recover from endometritis, endometrial epithelial and stromal cells secrete the cytokine and chemokine, such as interleukin 6 (IL-6), IL-8, and monocyte chemotactic protein 1 (MCP1), to recruit immune cells. Moreover, the symptom of endometritis is prolonged in summer and we have recently indicated that hyperthermia suppresses and enhances the IL-6 production in response to lipopolysaccharide (LPS) challenge in endometrial epithelial and stromal cells, respectively. However, the mechanisms for the opposite reaction of IL-6 secretion in response to LPS challenge in both types of endometrial cells under hyperthermia conditions were still unclear. To reveal these mechanisms, both types of endometrial cells were cultured with LPS under the control (38.5°C) or hyperthermia (40.5°C) conditions and comprehensively analyzed differential gene expressions of them by RNA-seq. In addition, based on these results, we examined the effect of endoplasmic reticulum (ER) stress on the IL-6 production in both types of endometrial cells cultured with LPS under hyperthermia conditions. In comprehensive analysis, hyperthermia induced the ER stress in the endometrial stromal cells but not in the endometrial epithelial cells. Actually, we confirmed that hyperthermia increased the gene expression of BiP, ATF4, and sXBP1 and protein expression of BiP and phosphorylated inositol requiring 1, ER stress marker, in the endometrial stromal cells but not in the endometrial epithelial cells. Moreover, in the endometrial stromal cells exposed to LPS, activation and inhibition of ER stress enhanced the IL-6 production under control conditions and suppressed it under hyperthermia conditions, respectively. In this study, we could uncover the one of causes for the disruption of IL-6 production in response to LPS challenge in the endometrial cells under hyperthermia conditions. This finding might be a clue for the improvement of the symptom of endometritis in cows during summer.

Inflammatory pathways in the pathogenesis of iatrogenic laryngotracheal stenosis: what do we know?

Iatrogenic laryngotracheal stenosis (LTS) is pathologic airway narrowing due to scar formation following endotracheal intubation or tracheostomy. It is a chronic and recurrent disease that results in significant morbidity or even mortality. Current data suggests that inflammatory pathways play a significant role in mediating the deposition of collagen and extracellular matrix to generate this scar. In particular, the T-helper 2 cell and M2 macrophage axis appears to be activated in both animal models and patients with iatrogenic LTS. Interleukin-6 production in response to hypoxia has also been implicated. In this paper, we review the data supporting the roles of various inflammatory pathways in the pathogenesis of iatrogenic LTS, discuss potential therapeutic approaches targeting these mechanisms, and outline areas for future study.

P32 is Required for Appropriate Interleukin-6 Production Upon LPS Stimulation and Protects Mice from Endotoxin Shock

Sepsis is a major cause of morbidity and mortality in seriously ill patients and mitochondrial dysfunction is associated with poor outcomes in septic patients. Although interleukin-6 (IL-6) is a good prognostic marker for sepsis, the relationship between mitochondrial dysfunction and IL-6 remains poorly understood. We identified p32/C1QBP/HABP1 as a regulator of IL-6 production in response to lipopolysaccharide (LPS). LPS induced IL-6 overproduction in p32 deficient mouse embryonic fibroblasts (MEFs) through NF-κB independent but activating transcription factor (ATF) 4 dependent pathways. Short hairpin RNA-based knockdown of ATF4 in p32 deficient MEFs markedly inhibited LPS-induced IL-6 production. Furthermore, MEFs treated with chloramphenicol, an inhibitor of mitochondrial translation, produced excessive IL-6 via ATF4 pathways. Using a LPS-induced endotoxin shock model, mice with p32 ablation in myeloid cells showed increased lethality and overproduction of IL-6. Thus, this study provides a molecular link how mitochondrial dysfunction leads to IL-6 overproduction and poor prognosis of sepsis.

Anti-inflammatory effect of Varthemia iphionoides extracts against prostate cancer in vitro

Varthemia iphionoides is a Jordanian medicinal plant with several health-promoting properties, including antibacterial, antioxidant and anticancer activities. However, its anti-inflammatory properties have been poorly investigated up to date. The current study aimed to investigate the anti-inflammatory effect of V. iphionoides by measuring the production of interleukin-6 in response to a pro-inflammatory stimulus (bacterial lipopolysaccharide) in in vitro cell models of human MRC-5 and PC3 cells. We observed a significant reduction in lipopolysaccharide-induced interleukin-6 release in response to V. iphionoides (125 µg/mL) in both non-cancerous fibroblast MRC-5 and prostate cancerous PC3 cells. However, the anti-inflammatory effect of this medicinal plant was stronger when MRC-5 cells were treated with an aqueous extract, while the methanolic extract was more potent in PC3 cells. The effect of V. iphionoides in reducing interleukin-6 production was not due to its cytotoxicity, and future studies are required to elucidate the mechanisms of action by which this medicinal plant modulates inflammatory responses. In conclusion, the results of our study represent the first report of the potential protective effect of water and methanolic extracts of V. iphionoides against pro-inflammatory stimuli in fibroblasts and cancer cells of human origin, and it is critically important to identify the phytochemical compounds responsible for this effect.

Defining a Role for Acid Sphingomyelinase in the p38/Interleukin-6 Pathway

Acid sphingomyelinase (ASM) is one of the key enzymes involved in regulating the metabolism of the bioactive sphingolipid ceramide in the sphingolipid salvage pathway, yet defining signaling pathways by which ASM exerts its effects has proven difficult. Previous literature has implicated sphingolipids in the regulation of cytokines such as interleukin-6 (IL-6), but the specific sphingolipid pathways and mechanisms involved in inflammatory signaling need to be further elucidated. In this work, we sought to define the role of ASM in IL-6 production because our previous work showed that a parallel pathway of ceramide metabolism, acid β-glucosidase 1, negatively regulates IL-6. First, silencing ASM with siRNA abrogated IL-6 production in response to the tumor promoter, 4β-phorbol 12-myristate 13-acetate (PMA), in MCF-7 cells, in distinction to acid β-glucosidase 1 and acid ceramidase, suggesting specialization of the pathways. Moreover, treating cells with siRNA to ASM or with the indirect pharmacologic inhibitor desipramine resulted in significant inhibition of TNFα- and PMA-induced IL-6 production in MDA-MB-231 and HeLa cells. Knockdown of ASM was found to significantly inhibit PMA-dependent IL-6 induction at the mRNA level, probably ruling out mechanisms of translation or secretion of IL-6. Further, ASM knockdown or desipramine blunted p38 MAPK activation in response to TNFα, revealing a key role for ASM in activating p38, a signaling pathway known to regulate IL-6 induction. Last, knockdown of ASM dramatically blunted invasion of HeLa and MDA-MB-231 cells through Matrigel. Taken together, these results demonstrate that ASM plays a critical role in p38 signaling and IL-6 synthesis with implications for tumor pathobiology.

A prospective study to assess the levels of interleukin-6 following administration of diclofenac, ketorolac and tramadol after surgical removal of lower third molars.

The surgical removal of impacted third molars involves, trauma to soft and bony tissue and can result in considerable pain, swelling, and trismus. The greater the amount of tissue injury the greater is the amount of inflammation in the perisurgical region. Interleukin-6 (IL-6) is both a pro inflammatory and anti-inflammatory cytokine. It is secreted by T cells and macrophages to stimulate the immune response. IL-6 is also an early marker of tissue damage. In addition to NSAIDs, corticosteroids, opioids also have immunomodulatory effects. To evaluate the changes in serum IL-6 levels following surgical removal of third molars under local anaesthesia after administration of two NSAIDs diclofenac and ketorolac and opioid tramadol post operatively. Patients undergoing surgical removal of impacted mandibular third molar teeth were randomly assigned to three groups. Each group received one of the three analgesics viz diclofenac 50mg, ketorolac 10mg and tramadol 50mg. The mean levels of IL-6 was then estimated by ELISA. The results of our study showed that all three drugs i.e. diclofenac, ketorolac and tramadol have properties which can downregulate the production of IL-6 in response to surgical trauma. It is of clinical significance that the suppression of IL-6 values occurs in tramadol group closely following the diclofenac group. Even though the drug ketorolac suppresses the IL-6 levels similar to diclofenac initially but after 7days tramadol and ketorolac showed similarities in suppression of IL-6 expression which is less compared to diclofenac group.

STAT3 tyrosine phosphorylation is critical for interleukin 1 beta and interleukin-6 production in response to lipopolysaccharide and live bacteria

Both interleukin 1 beta (IL-1β) and interleukin-6 (IL-6) are pro-inflammatory cytokines that play a major role in inflammatory diseases as well as cancer. In this work we investigated the signaling pathway involving lipopolysaccharide (LPS)-mediated IL-1β and IL-6 production in murine macrophage cell lines and primary macrophages. We show that in response to LPS, the JAK/STAT pathway is activated, leading to tyrosine phosphorylation at residue 705 on STAT3 and at residue 701 on STAT1, respectively. A newly developed STAT3 specific inhibitor (stattic) blocked LPS-mediated STAT3 tyrosine phosphorylation and led to inhibition of LPS-mediated IL-1β and IL-6 production but not TNF-α production. Knockdown of STAT3 expression via small interfering RNA (siRNA) decreased the level of STAT3 expression in Raw 264.7 cells and decreased STAT3 tyrosine phosphorylation in response to LPS treatment. Quantitative real time PCR and Western analysis of cells treated with inhibitor or STAT3 siRNA after LPS treatment showed a significant reduction of IL-1β and IL-6 mRNA and protein compared to cells treated with LPS alone. Moreover stattic abrogated IL-1β formation in response to extracellular bacteria Staphylococcus aureus and Escherichia coli in murine peritoneal macrophages. This inhibition did not affect caspase-1 activation. These results highlight the complex role of STAT3 in cytokine production and the key role of STAT3 tyrosine phosphorylation in IL-1β and IL-6 production in response to inflammation.

Signaling Pathways Leading to the Activation of IKK and MAPK by Thymosin α1

Thymosin alpha 1 (Talpha1) has therapeutic potential in the treatment of infectious diseases and cancer. However, the exact molecular pathways for Talpha1 action are not fully understood. We found that Talpha1 induces the production of interleukin-6 (IL-6), IL-10, and IL-12 in murine bone marrow-derived macrophages (BMDMs) through IKK and MAPK pathways. Talpha1 triggers the activation of AP-1 and the phosphorylation of JNK and p38. Inhibition of p38 impairs IL-6 production in response to Talpha1. Further, TRAF6 is involved in the activation of JNK and IRAK4 is involved for the activation of IKK and PKCzeta in a Talpha1-induced system. Loss of IRAK4 largely blocked induction of IL-6. Thus, our studies define early signal events that are critical for the Talpha1-induced immune responses.

Progesterone reduces lipopolysaccharide induced interleukin-6 secretion in fetoplacental chorionic arteries, fractionated cord blood, and maternal mononuclear cells

The purpose of this study was to characterize effect of progesterone (P4) on interleukin-6 (IL-6) production by fetoplacental artery explants, fetal granulocytes, and fetal and maternal mononuclear cells. Arteries and cord blood were obtained from 5 term pregnancies undergoing repeat cesarean section. Maternal blood was obtained from another 6 women at 16 to 20 weeks' gestation. Tissues were fractionated by dissection or Histopaque gradient. Specimens were incubated in physiologic media then exposed to lipopolysaccharide (LPS) or P4 alone, or pretreated with P4 and then exposed to LPS. Samples were evaluated for IL-6 by enzyme-linked immunosorbent assay (ELISA). Arteries and fetal and maternal mononuclear cells exposed to LPS increased IL-6 secretion by 9-, 27-, and 29-fold, respectively. P4 pretreatment blocked LPS induction of IL-6. Fetal granulocytes did not increase IL-6 production in response to LPS exposure. LPS induces IL-6 in arteries and fetal and maternal mononuclear cells. P4 pretreatment significantly blocks this effect in these cell populations, suggesting possible targets for anti-inflammatory actions of P4 in prevention of preterm birth.

Functional analysis of PU.1 domains in monocyte-specific gene regulation

The Ets family transcription factor PU.1 is required for the development of various lymphoid and myeloid cell lineages, and regulates the expression of several genes in a cell type-specific manner. Recently we found that overproduction of PU.1 in mouse bone marrow-derived mast cell progenitors induced the expression of monocyte-specific genes. This prompted us to analyze the functions of each domain of PU.1 in monocyte-specific gene expression, using transfection of mast cell progenitors with a series of retrovirus vectors for overexpression of various truncation mutants. Both the acidic region and the Ets domain of PU.1 were required for expression of monocyte-specific genes, and for enhanced interleukin-6 production in response to lipopolysaccharide. The Gln-rich region was suggested to be involved in expression of both MHC class II and F4/80. On the other hand, when PU.1 protein lacking the PEST domain was produced in the progenitor cells, expression of monocyte-specific genes was substantially enhanced, suggesting that the PEST domain plays a negative role in monocyte-specific gene expression.

Acylation of lysophosphatidylcholine plays a key role in the response of monocytes to lipopolysaccharide.

Mononuclear phagocytes play a pivotal role in the progression of septic shock by producing tumor necrosis factor-alpha (TNF-alpha) and other inflammatory mediators in response to lipopolysaccharide (LPS) from Gram-negative bacteria. Our previous studies have shown monocyte and macrophage activation correlate with changes in membrane phospholipid composition, mediated by acyltransferases. Interferon-gamma (IFN-gamma), which activates and primes these cells for enhanced inflammatory responses to LPS, was found to selectively activate lysophosphatidylcholine acyltransferase (LPCAT) (P < 0.05) but not lysophosphatidic acid acyltransferase (LPAAT) activity. When used to prime the human monocytic cell line MonoMac 6, the production of TNF-alpha and interleukin-6 (IL-6) was approximately five times greater in cells primed with IFN-gamma than unprimed cells. Two LPCAT inhibitors SK&F 98625 (diethyl 7-(3,4,5-triphenyl-2-oxo2,3-dihydro-imidazole-1-yl)heptane phosphonate) and YM 50201 (3-hydroxyethyl 5,3'-thiophenyl pyridine) strongly inhibited (up to 90%) TNF-alpha and IL-6 production in response to LPS in both unprimed MonoMac-6 cells and in cells primed with IFN-gamma. In similar experiments, these inhibitors also substantially decreased the response of both primed and unprimed peripheral blood mononuclear cells to LPS. Sequence-based amplification methods showed that SK&F 98625 inhibited TNF-alpha production by decreasing TNF-alpha mRNA levels in MonoMac-6 cells. Taken together, the data from these studies suggest that LPCAT is a key enzyme in both the pathways of activation (priming) and the inflammatory response to LPS in monocytes.

Toll-like Receptor-mediated Tumor Necrosis Factor and Interleukin-10 Production Differ during Systemic Inflammation

Major trauma is associated with a decreased capacity of patients' leukocytes to produce proinflammatory cytokines on in vitro stimulation. We studied leukocytes from 48 patients with trauma and showed that this hyporeactivity was restricted to gram-negative bacteria, Escherichia coli endotoxin, and unmethylated bacterial DNA, whereas Leptospira interrogans endotoxin-induced tumor necrosis factor production was similar to that observed with healthy donors. As well, tumor necrosis factor and interleukin-6 production in response to gram-positive bacteria was not altered. The expression of toll-like receptor (TLR) 2 was not reduced on patients' monocytes as compared with healthy control subjects, whereas that of TLR4 was reduced. However, the hyporeactivity to gram-negative bacteria and E. coli endotoxin cannot be fully explained by the downregulation of TLR4. Indeed, unlike proinflammatory cytokines, after stimulation with these microbial products the release of antiinflammatory cytokines was increased as compared with healthy control subjects. The increased interleukin-10 production was analyzed in terms of intracellular signaling in peripheral blood mononuclear cells from patients with trauma: our results suggest the involvement of p38 mitogen-activated protein kinase, Sp-1 transcription factor, heterotrimeric Gi protein, and phosphatidylinositol-3'-kinase. In conclusion, the immunodysregulation described for patients with trauma is not a generalized phenomenon but depends on the stimulus and the signaling pathway.

Production of IL-6 by human myoblasts stimulated with Abeta: relevance in the pathogenesis of IBM.

To determine whether amyloid-beta protein (Abeta) can induce the production of proinflammatory cytokines by cultured normal muscle cells. Sporadic inclusion body myositis (IBM) is characterized by the presence of rimmed vacuoles and fibrillary inclusions of Abeta in muscle fibers, and often inflammatory cells. Endomysial expression of proinflammatory molecules has suggested an ongoing immune process, but the site of sensitization and the mechanisms that trigger an inflammatory reaction is unknown. The authors used Northern blot analysis and specific immunoassays to study the expression and secretion in cell-free supernatants of tumor necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) by purified human myoblasts and C2C12 mouse skeletal muscle cells incubated with Abeta[1-42] or Abeta[25-35] peptides. Nonstimulated muscle cells produced detectable IL-6, whereas secretion of IL-1beta and TNFalpha was absent. Incubation with Abeta peptides increased IL-6 production, whereas TNFalpha and IL-1beta levels remained undetectable. Northern blot analysis of Abeta-stimulated human myoblasts revealed an increase in IL-6 mRNA expression. Cultured muscle cells increase the constitutive production of IL-6 in response to local deposition of Abeta in sporadic IBM. IL-6 could be a CD8(+) proliferation and differentiation agent, an autocrine proteolysis-inducing factor of damaged myotubes, and a proliferation-stimulating agent for satellite cells to replace the destroyed myofibers in IBM.

Endotoxin Stimulates Hepatocyte Interleukin-6 Production

Background. Interleukin-6 (IL-6) is a multifunctional cytokine which mediates many aspects of the acute phase response. Although known to be produced by macrophages and other proinflammatory cells, IL-6 is also released by many types of epithelial cells. The present studies were performed to determine if endotoxin and proinflammatory cytokines stimulate the release of IL-6 from native murine hepatocytes.Methods. Cultured hepatocytes were treated with various concentrations of lipopolysaccharide (LPS), interleukin-1 (IL-1), or tumor necrosis factor (TNF), in the presence or absence of the IL-1 receptor antagonist (IL-1 RA), an anti-TNF antibody, or dexamethasone. Culture supernatants were assayed for murine IL-6 using an ELISA. The cellular source of IL-6 was investigated using immunohistochemical staining.Results. Hepatocyte IL-6 production was significantly increased following treatment with LPS, IL-1, and TNF. Combinations of LPS and these cytokines were synergistic in stimulating IL-6 release. Dexamethasone, but not IL-1 RA or an anti-TNF antibody, inhibited hepatocyte production of IL-6 in response to LPS. Immunohistochemical staining revealed that the hepatocytes, and not contaminating nonparenchymal cells, were the principal source of the IL-6 produced in these cultures.Conclusions. Murine hepatocytes release significant amounts of IL-6 when exposed to endotoxin or proinflammatory cytokines. LPS appears to stimulate hepatocyte IL-6 production directly, and this effect does not appear to be mediated by IL-1 or TNF.

Conditionally Immortalized Murine Bone Marrow Stromal Cells Mediate Parathyroid Hormone-Dependent Osteoclastogenesis in Vitro

PTH recruits and activates osteoclasts to cause bone resorption. These actions of PTH are thought to be mediated indirectly via type 1 PTH/PTH-related peptide receptors (PTH1Rs) expressed by adjacent marrow stromal or osteoblastic cells, although some evidence suggests that PTH may act directly on early hematopoietic osteoclast progenitors. We have established clonal, conditionally immortalized, PTH-responsive, bone marrow stromal cell lines from mice that harbor both a transgene encoding a temperature-sensitive mutant of the simian virus 40 large T antigen and deletion of a single allele of the PTH1R gene. Of 60 stromal cell lines isolated, 45 expressed functional PTH1Rs. During coculture with normal murine spleen cells, 5 of 42 such cell lines could support formation of tartrate-resistant acid phosphatase-positive, multinucleated cells (TRAP+ MNCs) in response to 1,25-dihydroxyvitamin D3, but only 2 of these did so in response to PTH. One of these, MS1 cells, expressed numerous cytokines and proteins characteristic of the osteogenic lineage and showed increased production of interleukin-6 in response to PTH. MS1 cells supported dose-dependent induction by rat (r) PTH-(1–34) (0.1–100 nm) of TRAP+ MNCs that expressed calcitonin receptors and formed resorption lacunae on dentine slices. This effect of PTH, which required cell to cell contact between MS1 and spleen cells, was mimicked by coadministration of cAMP analog and phorbol ester but only partially by either agent alone. The carboxyl-terminal fragment rPTH-(53–84) also induced osteoclast-like cell formation, but the maximal effect was only 30% as great as that of rPTH-(1–34). Importantly, rPTH-(1–34) induced TRAP+ MNC formation even when PTH1R−/− osteoclast progenitors (from fetal liver of mice homozygous for ablation of the PTH1R gene) were cocultured with MS1 cells. We conclude that activation of PTH1Rs on cells of the osteoclast lineage is not required for PTH-(1–34)-induced osteoclast formation in the presence of appropriate PTH-responsive marrow stromal cells. MS1 cells provide a useful model for further study of PTH regulation of osteoclastogenesis.

Conditionally immortalized murine bone marrow stromal cells mediate parathyroid hormone-dependent osteoclastogenesis in vitro.

PTH recruits and activates osteoclasts to cause bone resorption. These actions of PTH are thought to be mediated indirectly via type 1 PTH/PTH-related peptide receptors (PTH1Rs) expressed by adjacent marrow stromal or osteoblastic cells, although some evidence suggests that PTH may act directly on early hematopoietic osteoclast progenitors. We have established clonal, conditionally immortalized, PTH-responsive, bone marrow stromal cell lines from mice that harbor both a transgene encoding a temperature-sensitive mutant of the simian virus 40 large T antigen and deletion of a single allele of the PTH1R gene. Of 60 stromal cell lines isolated, 45 expressed functional PTH1Rs. During coculture with normal murine spleen cells, 5 of 42 such cell lines could support formation of tartrate-resistant acid phosphatase-positive, multinucleated cells (TRAP+ MNCs) in response to 1,25-dihydroxyvitamin D3, but only 2 of these did so in response to PTH. One of these, MS1 cells, expressed numerous cytokines and proteins characteristic of the osteogenic lineage and showed increased production of interleukin-6 in response to PTH. MS1 cells supported dose-dependent induction by rat (r) PTH-(1-34) (0.1-100 nM) of TRAP+ MNCs that expressed calcitonin receptors and formed resorption lacunae on dentine slices. This effect of PTH, which required cell to cell contact between MS1 and spleen cells, was mimicked by coadministration of cAMP analog and phorbol ester but only partially by either agent alone. The carboxyl-terminal fragment rPTH-(53-84) also induced osteoclast-like cell formation, but the maximal effect was only 30% as great as that of rPTH-(1-34). Importantly, rPTH-(1-34) induced TRAP+ MNC formation even when PTH1R-/- osteoclast progenitors (from fetal liver of mice homozygous for ablation of the PTH1R gene) were cocultured with MS1 cells. We conclude that activation of PTH1Rs on cells of the osteoclast lineage is not required for PTH-(1-34)-induced osteoclast formation in the presence of appropriate PTH-responsive marrow stromal cells. MS1 cells provide a useful model for further study of PTH regulation of osteoclastogenesis.

Augmented expression of platelet-activating factor receptor gene by TNF-alpha through transcriptional activation in human monocytes.

Tumor necrosis factor alpha (TNF-alpha) is a cytokine produced by activated monocytes and often associated with platelet-activating factor (PAF) during the pathogenesis of many inflammatory and infectious diseases. PAFR is a G-protein-coupled receptor constitutively expressed on monocytes. TNF-alpha (100-400 U/mL) significantly increased PAFR mRNA expression in human monocytes. This increase was seen after 1 h of stimulation and persisted up to 24 h. Actinomycin D pretreatment studies revealed a transcriptional increase in PAFR gene expression without effect on mRNA half-life. [3H]WEB 2086 binding studies showed a significant (43%) increase in specific binding sites in 24-h-treated cells without change in receptor affinity. Increased interleukin-6 production in response to PAF was also found in 24-h TNF-alpha-pretreated monocytes. These observations provide new evidence for TNF-alpha and PAF interactions in human monocytes during inflammatory processes through up-regulation of PAFR expression by TNF-alpha.

Bone marrow fibroblasts from children with aplastic anemia exhibit reduced interleukin-6 production in response to cytokines and viral challenge.

Defects of the bone marrow microenvironment have been implicated in the pathogenesis of aplastic anemia (AA). We examined granulocyte/macrophage colony-stimulating factor (GM-CSF) and IL-6 production in bone marrow fibroblasts from five children with AA in response to cytokines and viral challenge with cytomegalovirus (CMV). Cytokine-stimulated IL-6 production in patients' fibroblasts was significantly reduced, whereas GM-CSF production was found to be comparable to normal controls. Also, CMV-mediated stimulation of IL-6 production was significantly lower in bone marrow fibroblasts from patients with AA. During the late phase of CMV-infection, IL-6 production was suppressed in CMV-infected fibroblasts from patients with AA with 90% inhibition of IL-6 protein production and marked reduction in IL-6 mRNA accumulation. Defective IL-6 production in bone marrow fibroblasts might contribute to hematopoietic suppression in some patients with AA.

Regulation of the release of interleukin-6 from human astrocytoma cells.

Recent evidence suggests that the level of interleukin-6 (IL-6) is elevated in Alzheimer's disease (AD) brains. IL-6 is produced by reactive glial cells and could potentially affect neuronal survival. Understanding the biochemical mechanism that regulates the production and release of IL-6 by astrocytic cells may help to identify potential targets for therapeutic intervention in AD. In the present study, glial fibrillary acidic protein-positive human U373MG astrocytoma cells were used as a model of reactive astrocytes. Production of IL-6 in response to drug treatment was monitored with an ELISA assay. Histamine (1-100 microM), substance P (SP; 1-100 nM), and human interleukin-1 beta (IL-1 beta; 1-30 pM) stimulated the release of IL-6 in a time- and concentration-dependent manner, with EC50 values of 4.5 microM, 8 nM, and 4.5 pM, respectively. The respective effects of histamine, SP, and IL-1 beta were effectively blocked by the histamine H1, SP, and IL-1 receptor antagonists, supporting a receptor-mediated event for these agents. Both histamine and SP enhanced the formation of inositol phosphates and increase intracellular calcium levels, suggesting that the phosphatidylinositol bisphosphate/protein kinase C pathway may be involved in the IL-6 release process. Indeed, phorbol 12-myristate 13-acetate, a protein kinase C activator, also evoked IL-6 release from the U373MG cells. On the other hand, IL-1 beta, which produces a much more robust release of IL-6 than histamine or SP, has no effect on inositol phosphate formation or intracellular calcium levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Complex Modulation of Cytokine Induction by Endotoxin and Tumour Necrosis Factor from Peritoneal Macrophages of Rats by Diets Containing Fats of Different Saturated, Monounsaturated and Polyunsaturated Fatty Acid Composition

1. Responses to cytokines and other inflammatory stimuli have been shown to be enhanced by fats rich in n-6 polyunsaturated fatty acids and suppressed by fats rich in n-3 polyunsaturated fatty acids and oleic acid or poor in n-6 polyunsaturated fatty acids. 2. Corn oil is rich and coconut oil, olive oil and butter are poor in n-6 polyunsaturated fatty acids. Olive oil and butter are rich in oleic acid. Fish oil is rich in n-3 polyunsaturated fatty acids. 3. The present study examines the effects of feeding standard chow or corn, coconut, fish and olive oils and butter for 4 and 8 weeks on subsequent cytokine production by peritoneal macrophages of rats. 4. Tumour necrosis factor production in response to a lipopolysaccharide stimulus and interleukin-1 and interleukin-6 production in response to a tumour necrosis factor challenge were studied. 5. All fats produced a small, but statistically insignificant, reduction in tumour necrosis factor production, which was greatest for olive oil at 8 weeks. 6. After 4 weeks, fish and olive oil significantly reduced interleukin-1 production. After 8 weeks, coconut oil suppressed production of the cytokine, and the inhibitory effect of fish oil was still apparent. After 8 weeks, corn and olive oil enhanced interleukin-1 production. 7. After 4 weeks of feeding, fish and olive oil enhanced interleukin-6 production. After 8 weeks, the enhancement by these fats increased, and corn oil and butter also enhanced production. Coconut oil produced no modulatory effect.(ABSTRACT TRUNCATED AT 250 WORDS)