The effect of fish oil supplementation on cytokine production in children

The ex vivo production of inflammatory cytokines during fish oil supplementation (n-3 polyunsaturated fatty acids, n-3 PUFA) is a matter of considerable controversy. Studies on human subjects have generally reported decreased lymphocyte proliferation and decreased production of IL-2, interferon-gamma, IL-1beta, IL-6 and TNF-alpha, but other studies showed no effect or even increased production. There are no published reports on ex vivo cytokine production in children on long-term, n-3 PUFA supplementation. The current double-blind study explored cytokine production by peripheral blood mononuclear cells (PBMCs), with and without lipopolysaccharide (LPS) stimulation in children on 12 weeks' supplementation with 300 mg/day of n-3 PUFA. Twenty-one children (aged 8-12 years) were randomized to receive 1 g canola oil (control) or 300 mg n-3 PUFA + 700 mg canola oil in a chocolate spread. Blood was then drawn and PBMCs were separated and cultured for 24 h in a culture medium with or without 10 microg/mL LPS for 5 x 10(6) PBMCs. The pro-inflammatory cytokines, IL-1beta, TNF-alpha and IL-6, and the anti-inflammatory cytokines, IL-10 and IL-1RA, were evaluated by ELISA. The levels of all the cytokines were higher in non-stimulated and LPS-stimulated cultures, from n-3 PUFA-treated subjects as compared to controls. There was no difference in the IL-1beta/IL-1RA ratio between the two groups, with and without LPS stimulation. Nevertheless, the ratio tended to be lower in the treated subjects on both occasions. In conclusion, our results indicate an increased production of both pro-inflammatory and anti-inflammatory cytokines, with and without LPS stimulation, in children on 12 weeks' n-3 PUFA supplementation.     

Evaluation of monensin and brefeldin A for flow cytometric determination of interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha in monocytes.

Flow cytometry has become a powerful technique to measure intracellular cytokine production in lymphocytes and monocytes. Appropriate inhibition of the secretion of the produced cytokines is required for studying intracellular cytokine expression. The aim of this study was to compare the capacity of cytokine secretion inhibitors, monensin and brefeldin A, in order to trap cytokine production (interleukin-1 beta [IL-1beta], IL-6, tumor necrosis factor-alpha [TNF-alpha]) within peripheral blood monocytes. A two-color flow cytometric technique was used to measure intracellular spontaneous and lipopolysaccharide (LPS)-stimulated IL-1beta, IL-6, and TNF-alpha production in monocytes (CD14+) of whole blood cultures. The viability of monensin-treated monocytes was slightly lower than that of brefeldin A-inhibited monocytes, as measured with propidium iodide (PI). The percentage of IL-6 and TNF-alpha-producing monocytes after 8 h of culture without stimulation revealed significant lower values for monensin-treated than for brefeldin A-treated monocytes. The percentages for stimulated cells did not differ. The spontaneous intracellular production in molecules of equivalent soluble fluorochrome units (MESF) of IL-1beta, IL-6, and TNF-alpha after 8 h of culture was higher in brefeldin A than in monensin-inhibited monocytes. The LPS-stimulated intracellular production of IL-1beta, IL-6, and TNF-alpha was increased in brefeldin A-inhibited monocytes. In conclusion, for flow cytometric determination of intracellular monocytic cytokines (IL-1beta, IL-6, and TNF-alpha), brefeldin A is a more potent, effective, and less toxic inhibitor of cytokine secretion than monensin.     

Dysregulation of proinflammatory and regulatory cytokines in HIV infected persons with active tuberculosis

Proinflammatory and regulatory cytokines have been implicated to play important role in immunopathology of HIV and tuberculosis (TB) infection. Capacity of unstimulated and mitogen-stimulated peripheral blood mononuclear cells (PBMCs) to secrete cytokines (interleukin (IL)-2, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), IL-4, IL-10 and IL-6) was estimated for 15 HIV-TB coinfected patients, 22 HIV seropositives without TB, 32 HIV negative TB patients, and 36 healthy subjects. Dually infected patients had suppression of both Th1 and Th2 cytokine secretion as evidenced by significantly lower production of IL-2, IFN-gamma and TNF-alpha as well as IL-4 and IL-10. Production of IL-2 and TNF-alpha was significantly decreased only in case of HIV infection. Significantly higher IL-6 secretion was found in unstimulated cultures in dually infected patients. The mitogen induced cytokine secretion was generally lower in HIV-TB coinfected patients indicating profound perturbation of both Th1 and Th2 responses.     

IgE-dependent cytokine production by human peripheral blood mononuclear phagocytes.

These studies demonstrate the IgE-dependent production of IL-1 beta and TNF-alpha by circulating blood monocytes. IL-1 beta production was demonstrated biologically as the stimulation of proliferation of the cloned IL-1-dependent murine T cell line D10.G4.1 in the presence of a submitogenic concentration of PHA. In a representative experiment, 3H-thymidine uptake increased from 57826 cpm in the presence of supernatants obtained from unstimulated cells to 200774 cpm with supernatants from monocytes stimulated by IgE/alpha IgE immune complexes. By ELISA, IgE complexes increased IL-1 beta production from 0.54 +/- 0.06 ng (per 10(6) monocytes) to 2.60 +/- 0.62 ng (p less than 0.01; mean of eight experiments) and TNF-alpha production from 0.17 +/- 0.10 ng to 3.00 +/- 0.54 ng (p less than 0.01; mean of four experiments). No IL-1 alpha secretion was observed. RNA hybridization analysis demonstrated that IL-1 beta production represented de novo synthesis of the cytokine. Stimulated RNA production was observed after a minimal 1/2-h incubation and was maximal at 2 h. The IgE-dependent secretion of these pro-inflammatory cytokines by mononuclear phagocytic cells may contribute to the inflammation characteristic of allergic responses.     

Cytokine production after intravenous or peritoneal gram-negative bacterial challenge in mice. Comparative protective efficacy of antibodies to tumor necrosis factor-alpha and to lipopolysaccharide.

The production of TNF-alpha, IL-1, and IL-6 was measured in mice after bolus i.v. Escherichia coli O111 LPS injections and during bacteremia induced either by bolus i.v. or by i.p. challenges of live E. coli O111. High but transient TNF-alpha peaks were observed after bolus i.v. LPS or bacterial challenges. In contrast, the levels during lethal peritonitis increased progressively to values 50- to 100-fold lower than the peak values observed after i.v. injections, and remained sustained until death. Whereas after i.v. challenge with 1000 LD50 of LPS, anti-TNF-alpha antibody fully protected mice from death and reduced serum IL-1 and IL-6 levels, anti-TNF-alpha antibody did not improve the survival of mice nor reduced serum IL-1 and IL-6 levels after i.p. bacterial challenge. In contrast to anti-TNF-alpha antibodies, anti-LPS antibodies were protective in the peritonitis model. Protection was accompanied by a striking reduction of bacterial numbers and of TNF-alpha, IL-1, and IL-6 levels in the serum, but the levels of these cytokines were only marginally affected in the peritoneal lavage fluid. This latter observation demonstrates that the local peritoneal cytokines did not diffuse readily into the circulation, thus suggesting that at least part of the circulating cytokines are produced systemically. In conclusion, the striking differences between cytokine profiles as well as the divergent efficacy of anti-TNF-alpha antibody after i.v. bolus and after i.p. challenges suggest that TNF-alpha may not be as important in the pathogenesis of lethal peritonitis than after lethal acute bacteremia.     

Progesterone, but not 17beta-estradiol, increases TNF-alpha secretion in U937 monocytes

The Women Health Initiative Clinical trial results suggest that post-menopausal women receiving estrogen + progesterone are at risk for heart disease compared with estrogen alone supplemented women. We examined the hypothesis that progesterone but not 17beta-estradiol (E) increases the secretion of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha. U937 human monocytes were cultured with normal or high glucose in the presence and absence of estrogen or progesterone at 37 degrees C for 24 h. Results show that estrogen inhibits IL-6 but not TNF-alpha secretion (p < 0.05) in monocytes activated by lipopolysaccharide (LPS) or high glucose. In addition, progesterone increased the TNF-alpha secretion in activated monocytes. Thus, progesterone supplementation along with estrogen may increase blood levels of pro-inflammatory cytokine TNF-alpha and thus risk of heart disease in post-menopausal women.     

HIV induces IL-6 production by human B lymphocytes. Role of IL-4.

In vitro, normal B cells can produce TNF-alpha and IL-6 when activated with a first signal, and cytokines and B lymphocytes from some HIV-infected individuals spontaneously secrete TNF-alpha and IL-6, although the direct involvement of HIV has not been fully explored. In this study, we examined the effects of HIV (purified virus and a recombinant envelope protein) and various IL on TNF-alpha and IL-6 in vitro production by highly purified normal B cells. HIV alone did not induce IL-6 or TNF-alpha production by B cells from healthy subjects. HIV induced IL-6 production (500 to 1500 pg) in the presence of IL-4, with a slight production of TNF-alpha. IL-6 production occurred independently of the presence or absence of TNF-alpha in contrast with Staphylococcus aureus cowan + IL-2-activated B cells. Other IL, particularly IL-2, were unable to induce IL-6 secretion by HIV-activated B cells. In vivo-activated B cells from HIV-infected patients spontaneously produce moderate quantities of IL-6 and TNF-alpha. This secretion was markedly increased by HIV, suggesting that IL-6-secreting B cells contain anti-HIV antibody-producing B cells. However, contrary to normal B cells, IL-6 production by B cells from HIV-infected patients was not further enhanced by IL-4. Then HIV itself is able to induce an autocrine production of IL-6 upon interaction with IL-4, which can contribute to the hypergammaglobulinemia and to the global B cell dysfunction observed in HIV-infected patients.     

Quantitative role of p42/44 and p38 in the production and regulation of cytokines TNF-alpha, IL-1beta and IL-12 by murine peritoneal macrophages in vitro by concanavalin A

In the present study the quantitative role of p42/44 and p38 in the production of TNF-alpha, IL-1beta and IL-12 by murine peritoneal macrophages, in vitro, on treatment with Concanavalin A (ConA) has been investigated. Maximum expression/production of cytokines TNF-alpha, IL-1beta and IL-12 was observed after 16 h by RT-PCR and 24 h by ELISA, on in vitro treatment with ConA. To investigate the role of MAP kinases in the production of cytokines, pharmacological inhibitors of MAP kinases--PD98059, SB202190 and SP600125, were used. The expression of TNF-alpha, IL-1beta and IL-12 was down regulated in the presence of PD98059 and SB202190 in a dose dependent manner, suggesting the involvement of p42/44 and p38 in ConA induced production of TNF-alpha, IL-1beta and IL-12 by macrophages. It was observed that SP600125 did not have any effect on the expression of TNF-alpha, IL-1beta and IL-12. Using different combinations of MAPK inhibitors, it was found that 45% signal is conveyed via p42/44 and 25% via p38 in the production of these cytokines, by ConA treated macrophages while 30% signal passes through unidentified pathways.     

Influence of carbohydrate ingestion on immune changes after 2 h of intensive resistance training.

Thirty strength-trained subjects were randomized to carbohydrate (CHO) or placebo (Pla) groups and lifted weights for 2 h (10 exercises, 4 sets each, 10 repetitions, with 2- to 3-min rest intervals). Subjects received 10 ml x kg(-1) x h(-1) CHO (6%) or Pla beverages during the weight training bout. Blood, saliva, and vastus lateralis muscle biopsy samples were collected before and after exercise. Blood cell counts were determined, and plasma was analyzed for IL-6, IL-10, IL-1 receptor antagonist (IL-1ra), IL-8, and cortisol. Muscle was analyzed for glycogen content and relative gene expression of 13 cytokines (IL-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p35, IL-12p40, IL-15, IFN-gamma, TNF-alpha) by use of real-time quantitative RT-PCR. Significant but modest increases were measured for plasma IL-6, IL-10, IL-1ra, and IL-8, but the pattern of increase did not differ between CHO and Pla groups. The rate of decrease in muscle glycogen content did not differ between CHO and Pla (P = 0.463). Muscle cytokine mRNA was detected preexercise for IL-1beta, IL-6, IL-15, IL-8, and TNF-alpha, and of these, IL-1beta, IL-6, IL-8, and TNF-alpha were significantly increased after the 2-h weight training bout. The increase in mRNA (fold difference from preexercise) did not differ between CHO and Pla groups. In summary, CHO vs. Pla ingestion did not alter modest increases measured for plasma IL-6, IL-10, IL-1ra, and IL-8, and muscle gene expression for IL-1beta, IL-6, IL-8, and TNF-alpha in strength-trained subjects lifting weights intensively for 2 h.     

Recombinant rat IL-1beta and IL-6 synergistically enhance C3 mRNA levels and complement component C3 secretion by H-35 rat hepatoma cells

Hepatic synthesis of complement component C3 is regulated in part by inflammatory cytokines. Rat models are frequently employed to investigate pathogenic roles of complement and cytokines. However, cytokines obtained from species other than the rat were used in previous studies of cytokine regulation of C3 synthesis in rat hepatocytes or hepatoma cells. It is not known whether these prior reports predict hepatocellular responses evoked by rat cytokines. Therefore, H-35 rat hepatoma cells were employed to measure the effect of recombinant rat IL-1beta, IL-6, IFN-gamma, and TNF-alpha on C3 protein secretion and C3 mRNA levels quantified by ELISA and quantitative RT-PCR. Compared to untreated control cells, H-35 cells treated with IL-1beta, IL-6, and IFN-gamma increased C3 secretion approximately 10-, 4-, and 2-fold, respectively. TNF-alpha was toxic, precluding further analysis. IL-1beta and IL-6 demonstrated synergy with respect to the quantity and rate of increase of C3 mRNA measured and the magnitude of C3 protein secretion. Previous reports using non-rat cytokines did not consistently predict H-35 responses to rat cytokines. Consequently, we recommend the use of rat cytokines in rat models that include analysis of cytokine-mediated events.     

Release of reactive nitrogen intermediates and reactive oxygen intermediates from mouse peritoneal macrophages. Comparison of activating cytokines and evidence for independent production

The capacity of 12 cytokines to induce NO2- or H2O2 release from murine peritoneal macrophages was tested by using resident macrophages, or macrophages elicited with periodate, casein, or thioglycollate broth. Elevated H2O2 release in response to PMA was observed in resident macrophages after a 48-h incubation with IFN-gamma, TNF-alpha, TNF-beta, or CSF-GM. Of these, only IFN-gamma induced substantial NO2- secretion during the culture period. The cytokines inactive in both assays under the conditions tested were IL-1 beta, IL-2, IL-3, IL-4, IFN-alpha, IFN-beta, CSF-M, and transforming growth factor-beta 1. Incubation of macrophages with IFN-gamma for 48 h in the presence of LPS inhibited H2O2 production but augmented NO2- release, whereas incubation in the presence of the arginine analog NG-monomethylarginine inhibited NO2- release but not H2O2 production. Although neither TNF-alpha nor TNF-beta induced NO2- synthesis on its own, addition of either cytokine together with IFN-gamma increased macrophage NO2- production up to six-fold over that in macrophages treated with IFN-gamma alone. Moreover, IFN-alpha or IFN-beta in combination with LPS could also induce NO2- production in macrophages, as was previously reported for IFN-gamma plus LPS. These data suggest that: 1) tested as a sole agent, IFN-gamma was the only one of the 12 cytokines capable of inducing both NO2- and H2O2 release; 2) the pathways leading to secretion of H2O2 and NO2- are independent; 3) either IFN-gamma and TNF-alpha/beta or IFN-alpha/beta/gamma and LPS can interact synergistically to induce NO2- release.     

Cytokine-mediated modulation of leptin and adiponectin secretion during in vitro adipogenesis: evidence that tumor necrosis factor-alpha- and interleukin-1beta-treated human preadipocytes are potent leptin producers

Over the last decade, compelling evidence has been presented that cytokines affect adipocyte tissue formation and function. In this study we explored the effect of pro-inflammatory (i.e. interleukin (IL)-1beta, IL-6, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha) versus anti-inflammatory cytokines (i.e. IL-4, IL-10, and transforming growth factor (TGF)-beta1) on leptin and adiponectin secretion during in vitro human adipogenesis. Confirmative to previous reports, conversion of precursor preadipocytes into mature adipocytes was completely inhibited upon exposure to TNF-alpha, IL-1beta, IFN-gamma, or TGF-beta1. Hence, all these anti-adipogenic cytokines prevented release of adipocyte-specific adiponectin. IFN-gamma also strongly reduced leptin production (> or =85%). However, TNF-alpha, IL-1beta, and TGF-beta1 stimulated leptin production from preadipocytes in the absence of mature adipocytes (20.6+/-5.4 ng/ml, 100.8+/-18.2 ng/ml, and 5.4+/-0.4 ng/ml, respectively, compared to 6.6+/-0.8 ng/ml in control adipocyte cultures on day 21; n=4). IL-4, IL-6 and IL-10 did not, or only slightly, affect adipocyte differentiation and their hormonal secretion. In conclusion, adiponectin and leptin are both synthesized by adipocytes, whereas leptin is also produced by preadipocytes upon TNF-alpha or IL-1beta stimulation. These data suggest that preadipocytes could contribute more to total circulating leptin levels than has been previously considered, especially in diseased conditions were these pro-inflammatory factors play a prominent role.     

A specific inhibitor of the p38 mitogen activated protein kinase affects differentially the production of various cytokines by activated human T cells: dependence on CD28 signaling and preferential inhibition of IL-10 production

Cytokine production upon T cell activation results from the integration of multiple signaling pathways from TCR/CD3 and from costimulatory molecules such as CD28. Among these pathways, the possible role of p38 mitogen activated protein kinase (MAPK) is the least understood. Here, we used a highly specific p38 MAPK inhibitor, the SB203580 compound, to examine the role of this enzyme in the induction of various cytokines in human T cells stimulated with anti-CD3 and anti-CD28 mAb together or in combination with PMA. Cytokine induction was monitored by ELISA and at the mRNA level. While SB203580 had little effect on IL-2 production and proliferation, it significantly reduced the production of several other cytokines. The secretion of IL-4, IL-5, IL-13, and TNF-alpha was inhibited by 20-50% with modes of T cell activation involving the CD28 pathway, whereas their mRNA expression was little affected. In contrast, IFN-gamma induction via CD28/PMA or CD3/CD28, but not CD3/PMA, was markedly diminished both at the protein and at the mRNA levels. Most interestingly, SB203580 also suppressed IL-10 secretion and mRNA induction via CD28-dependent activation by 75-85% (IC50 approximately 0.2 microM). Subset analysis suggested that this inhibition did not reflect a differential effect on T cell subsets. Therefore, p38 MAPK activity appears to contribute to cytokine production, mostly via CD28-dependent signaling. Moreover, IL-10 seems to rely more on this activity than other cytokines for its induction in T cells.     

Four cell-secreted cytokines act synergistically to maintain long term proliferation of human B cell lines in vitro.

Autocrine production of growth factors is thought to be an essential element in the development of hemopoietic tumors in vivo. Tumor-derived cell lines frequently show this capability in vitro. It is not understood how autonomous growth in vitro is maintained by lymphoid cell lines that are not of tumorigenic origin. We have previously established human B cell clones that proliferate in serum-free media with unlimited potential. However, the cells need a critical density for continuous growth. Culture supernatant conditioned by these cell lines sustained proliferation even in low density cultures. All B cell clones analyzed were found to secrete the cytokines IL-1 alpha, IL-6, TNF-alpha, and TNF-beta whereas no activity of IL-2, IL-4, low m. w.-B cell growth factor, CSF, or IFN-gamma was recorded. In low density cultures supplemented with rIL-1 alpha, +/- IL-6, +/- TNF-alpha, and +/- TNF-beta together, B cell proliferation is maintained to the same extent as with conditioned medium. Addition of anti-sense oligonucleotides directed to the mRNA of IL-1 alpha, IL-6, and TNF-alpha, respectively, resulted in growth arrest and cell death. This effect could be prevented by supplementation with these cytokines. Scatchard plot analyses and internalization studies revealed that the cells express on their surface high affinity receptors for IL-1 alpha, IL-6, and TNF, respectively, and internalize the cytokines from the supernatant. These results demonstrate that (i) autonomous growth of immortalized B cells is maintained by secretion and reinternalization of IL-1 alpha, IL-6, TNF-alpha, and TNF-beta, (ii) these cytokines act in a synergistic fashion, and (iii) autocrine growth stimulation of human B cells in vitro does not necessarily represent their tumorigenic potential in vivo.     

Stimulation of interleukin-6 release by interleukin-1beta from isolated human adipocytes

The secretion of interleukin-6 (IL-6) is modulated by immune, hormonal and metabolic stimuli in a cell-specific manner. We investigated the effect of cytokines, TNFalpha and IL-1beta, and insulin on IL-6 release from human adipocytes and peripheral blood cells (PBC). Adipocytes released IL-6 constitutively (after 5 h: 5.64 [1.61-15.30]pg ml(-1), after 10 h: 15.95 [2.34-45.59]pg ml(-1), p = 0.007), while PBC secretion did not change significantly over this period. LPS stimulated IL-6 secretion in PBC after 5 h but was without effect on adipocytes. TNFalpha and insulin induced IL-6 production from PBC, but had no effect on adipocytes. IL-1beta, however, induced a substantial increase in IL-6 release in adipocytes and PBC (all p < 0.05). Adipose tissue production of IL-1beta was assessed in vivo by measuring arterio-venous differences across the subcutaneous abdominal adipose bed. Net release of IL-1beta was not observed, suggesting that under basal conditions there is no detectable release of this cytokine into the circulation from this depot. In conclusion (1) PBC demonstrate regulated IL-6 release, while the adipocyte release has a large constitutive component; (2) immune modulators, such as LPS, TNFalpha and IL-1beta, all induce PBC IL-6 release, but only IL-1beta stimulates adipocyte release. Though IL-1beta is not an endocrine signal from adipose tissue, it is an autocrine/paracrine stimulator of IL-6 release from human adipocytes.     

Cytokine production by mature and immature thymocytes.

We have studied the ability of subpopulations of activated thymocytes to produce four cytokines (IL-2, IL-4, IFN-gamma and TNF-alpha) which are believed to play roles in T cell development. Supernatants from various thymocyte subsets activated with calcium ionophore and PMA were tested for these cytokines. All CD3hi thymocyte subsets (CD4+8-, CD4-8- and CD4-8+) produced high titers of these four cytokines except CD3+4-8+ thymocytes, which did not produce IL-4. In contrast, CD4+8+ thymocytes did not produce any detectable cytokines. CD3-4-8- thymocytes produced IL-2, IFN-gamma, and TNF-alpha (but not IL-4) when activated by calcium ionophore + PMA and IL-1. We then separated CD3-4-8- thymocytes into IL-2R+ and IL-2R-. CD3-4-8-IL-2R+ thymocytes only produced small amounts of IL-2 when activated with calcium ionophore + PMA + IL-1, whereas CD3-4-8-IL-2R- thymocytes did not require IL-1 to produce IL-2, IFN-gamma, and TNF-alpha. Finally, CD4-8+3- thymocytes (an immature population believed to be an intermediate between CD3-4-8- and CD4+8+ thymocytes) only produced marginally detectable levels of IL-2 upon stimulation with calcium ionophore, PMA, and the addition of IL-1 did not result in increased levels of cytokine production. These observations indicate discrete patterns of cytokine production by the subsets studied and suggest specific controls of cytokine gene expression during T cell development.     

Proinflammatory cytokines interact synergistically with epidermal growth factor to stimulate PGE2 production in amnion-derived cells.

Recent evidence has implicated cytokines and growth factors in the initiation of parturition in women. In the present study, the amnion-derived cell line WISH was used to determine whether proinflammatory cytokines (interleukins 1 beta, 6, and 8, tumor necrosis factor-alpha, and granulocyte/macrophage colony stimulating factor) could amplify epidermal growth factor-induced prostaglandin E2 production. WISH cells were preincubated with cytokines (0.0001-10 ng/ml) for 60 min and then challenged with EGF (10 ng/ml) for 4 hrs after which PGE2 production was measured by radioimmunoassay. EGF, IL-1 beta and TNF-alpha alone caused a dose-dependent increase in PGE2 production, while IL-6, IL-8 and GM-CSF were ineffective over the dose range tested. When cells were preincubated with IL-1 beta or TNF-alpha, there was a dose-dependent potentiation of EGF-induced PGE2 production that was greater than the sum of EGF alone and IL-1 beta or TNF-alpha alone. In each case, the minimum dose of IL-1 beta or TNF-alpha which amplified EGF-induced PGE2 production was 0.1 ng/ml (p less than 0.05, Student's t-test). These data show that low concentrations of IL-1 beta or TNF-alpha may serve to amplify EGF-mediated PGE2 biosynthesis in amnion-derived cells and suggest that cytokines may modulate EGF function in responsive cells.     

Curcumin protects against acute liver damage in the rat by inhibiting NF-kappaB, proinflammatory cytokines production and oxidative stress

Curcumin, an anti-inflammatory and antioxidant compound, was evaluated for its ability to suppress acute carbon tetrachloride-induced liver damage. Acute hepatotoxicity was induced by oral administration of CCl4 (4 g/kg, p.o.). Curcumin treatment (200 mg/kg, p.o.) was given before and 2 h after CCl4 administration. Indicators of necrosis (alanine aminotransferase) and cholestasis (gamma-glutamyl transpeptidase and bilirubins) resulted in significant increases after CCl4 intoxication, but these effects were prevented by curcumin treatment. As an indicator of oxidative stress, GSH was oxidized and the GSH/GSSG ratio decreased significantly by CCl4, but was preserved within normal values by curcumin. In addition to its antioxidants properties, curcumin is capable of preventing NF-kappaB activation and therefore to prevent the secretion of proinflammatory cytokines. Therefore, in this study we determined the concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) mRNA, and NF-kappaB activation. CCl4-administered rats depicted significant increases in TNF-alpha, IL-1beta, and IL-6 production, while curcumin remarkably suppressed these mediators of inflammation in liver damage. These results were confirmed by measuring TNF-alpha, and IL-1beta protein production using Western Blot analysis. Accordingly, these proteins were increased by CCl4 and this effect was abolished by curcumin. Administration of CCl4 induced the translocation of NF-kappaB to the nucleus; CCl4 induced NF-kappaB DNA binding activity was blocked by curcumin treatment. These findings suggest that curcumin prevents acute liver damage by at least two mechanisms: acting as an antioxidant and by inhibiting NF-kappaB activation and thus production of proinflammatory cytokines.