Modulation of endotoxin- and enterotoxin-induced cytokine release by in vivo treatment with beta-(1,6)-branched beta-(1,3)-glucan

Leukocytes activated by endotoxin or enterotoxins release proinflammatory cytokines, thereby contributing to the cascade of events leading to septic shock. In the present studies, we analyzed the effects of in vivo administration of a soluble immunomodulator, beta-(1,6)-branched beta-(1,3)-glucan (soluble beta-glucan), on toxin-stimulated cytokine production in monocytes and lymphocytes isolated from treated mice. In vitro stimulation of lymphocytes isolated from soluble beta-glucan-treated mice with lipopolysaccharide (LPS) resulted in enhanced production of interleukin-6 (IL-6) and suppressed production of tumor necrosis factor alpha (TNF-alpha), while stimulation of these cells with staphylococcal enterotoxin B (SEB) or toxic shock syndrome toxin 1 (TSST-1) resulted in enhanced production of gamma interferon (IFN-gamma) and suppressed production of IL-2 and TNF-alpha compared to that in cells isolated from untreated mice. In vitro stimulation of monocytes isolated from soluble beta-glucan-treated mice with LPS also resulted in suppressed TNF-alpha production, while stimulation of these cells with SEB or TSST-1 resulted in suppressed IL-6 and TNF-alpha production compared to that in cells isolated from untreated mice. Thus, the overall cytokine pattern of leukocytes from soluble beta-glucan-treated mice reflects suppressed production of proinflammatory cytokines, especially TNF-alpha. Taken together, our results suggest that treatment with soluble beta-glucan can modulate the induction cytokines during sepsis, resulting in an overall decrease in host mortality.     

Parathyroidectomy does not prevent the renal PTH/PTHrP receptor down-regulation in uremic rats

In a recent study we demonstrated that the PTH/PTHrP receptor (PTH-R) mRNA was markedly down-regulated in the remnant kidney of uremic rats with severe secondary hyperparathyroidism. Among the factors potentially implicated in this down-regulation, to date only PTH has been demonstrated to modulate PTH-R expression. Here, we examined the effect of thyroparathyroidectomy (TPTX) on the renal expression of PTH-R in rats with normal renal function or with chronic renal failure (CRF) induced by 5/6 nephrectomy. Four groups of rats were studied: control, TPTX, CRF, and CRF + TPTX. Moderate-degree renal failure was documented by mean (+/- SD) creatinine clearances (microliter/min/100 g body wt) of 259 +/- 40 and 212 +/- 45 in CRF and CRF + TPTX rats, compared with 646 +/- 123 and 511 +/- 156 in control and TPTX rats, respectively. Plasma phosphorus, calcitriol, and ionized calcium were significantly lower in CRF and CRF + TPTX than in control animals. Plasma ionized calcium and calcitriol were also lower in TPTX than in control rats. Plasma PTH levels (pg/ml) were increased in CRF rats (41.8 +/- 29.4), and markedly decreased in TPTX (10.1 +/- 7.8) and CRF + TPTX (8.0 +/- 3.8) rats compared with control rats (21.7 +/- 7.5). Northern blot analysis showed that the level of the steady-state PTH-R mRNA in the kidney of CRF and CRF + TPTX rats was markedly decreased compared with that of control rats, the ratios of PTH-R mRNA/beta-actin mRNA being 0.28 +/- 0.04 and 0.27 +/- 0.03 versus 0.54 +/- 0.05, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serial prognostic capabilities of electrocardiographic indices of infarcted and hibernating myocardium in predicting short- and long-term outcome following coronary artery bypass surgery

Concentrations and ex vivo production of interleukin 1 beta (IL-1), tumour necrosis alpha (TNF), interleukin 6 (IL-6), interleukin-1 receptor antagonist (IL-1RA) and TNF soluble receptors (sTNF-receptors, P55 and P75) were measured in bronchoalveolar lavage (BAL) fluid and blood in 23 HIV-seropositive (HIV+) patients with Pneumocystis carinii pneumonia (PCP) and compared with values found in healthy HIV-seronegative (HIV-) controls and asymptomatic HIV+ subjects. Concentrations of the proinflammatory cytokine IL-1 beta were increased in BAL fluid of HIV+ patients with PCP (184 +/- 47 pg mL-1) compared with undetectable levels in healthy control subjects (P = 0.0001). In plasma of these patients higher concentrations of the anti-inflammatory cytokine IL-1RA were found during acute PCP than after recovery (2.1 +/- 0.7 vs. 0.5 +/- 0.2 ng mL-1, P = 0.01). No correlations could be found between cytokine concentrations and clinical severity of the infection. Corticosteroid treatment did not influence cytokine concentrations in BAL or blood, nor did it suppress the production in alveolar cells. In whole-blood cultures, however, lipopolysaccharide (LPS)-stimulated production was significantly suppressed for IL-1 (1.3 vs. 5.5 ng mL-1, P = 0.009) and for IL-6 (0.6 vs. 2.5 ng mL-1, P = 0.01). The overall data show that in HIV+ patients with PCP (similar to what we had found previously in HIV-patients with PCP) proinflammatory cytokines are more prominently present in BAL, whereas anti-inflammatory reaction is predominant in the circulation.     

In vivo treatment with calcitriol (1,25(OH)2D3) reverses age-dependent alterations of intestinal calcium uptake in rat enterocytes

The vitamin D endocrine system has been involved in the impairment of intestinal calcium absorption during aging. Alterations in the nongenomic mechanism of calcitriol (1,25-dihydroxy-vitamin D3; [1, 25(OH)2D3] have been recently evidenced. In enterocytes isolated from aged rats, 1,25(OH)2D3 stimulation of Ca2+ channels through the cAMP/PKA pathway is blunted. We have now investigated whether in vivo administration of calcitriol to senescent rats reverses the absence of hormonal effects in isolated intestinal cells. In enterocytes from 20-24-month-old rats given 1,25(OH)2D3 for 3 days (30 ng/100 g bw/day), calcitriol (10(-10) M, 3-5 minutes) stimulated Ca2&plus uptake and intracellular cAMP to the same degree and protein quinase A (PKA) activity to a lesser degree than in enterocytes from young animals. Significantly higher basal levels of cAMP and PKA detected in enterocytes from old rats were not affected by prior injection of animals with 1,25(OH)2D3. When the aged rats were injected with 25(OH)D3, similar Ca2+ influx, cAMP, and PKA responses to in vitro stimulation with calcitriol were obtained. 1, 25(OH)2D3-dependent changes in Ca2+ uptake by enterocytes from both young and old rats treated with calcitriol were totally suppressed by the cAMP antagonist Rp-cAMPS, whereas the response to the agonist Sp-cAMPS was markedly depressed in aged animals. These results suggest that intestinal resistance to nongenomic 1,25(OH)2D3 stimulation of duodenal cell Ca2+ uptake develops in rats upon aging and show that in vivo administration of 1,25(OH)2D3 or its precursor to senescent rats restores the ability of the hormone to stimulate duodenal cell calcium influx through the cAMP messenger system.     

Correlation between the capacity to activate macrophages in vitro and the antitumor activity in vivo of lipopolysaccharides from different bacterial species

The correlation between the activation of macrophages by lipopolysaccharides (LPS) from four different bacterial species and their antitumor effect in a rat model of colon cancer was investigated. The efficacy of LPS from Neisseria meningitidis (Nm), Salmonella minnesota (Sm), Escherichia coli (Ec) and Bordetella pertussis (Bp) was evaluated as the smallest concentration inducing rat peritoneal macrophages (pm psi) to produce tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6 and nitric oxide (NO). The cytokine production was measured in bioassays and NO production quantitatively with Griess reactant. Nm was the most effective LPS with concentrations of 1 ng/10(6) pm psi for the induction of TNF, IL-1 and IL-6 activities and 0.01 ng/10(6) pm psi for the induction of NO production. The range between efficacy of different LPS was broad from 1 to 10(4)-10(5) for TNF activity, 1 to 10(2)-10(3) for NO production and IL-6 activity and 1 to 10-10(2) for IL-1 activity. In vivo antitumor effect was evaluated on the growth of peritoneal carcinomatosis. Complete tumor regressions were observed, the LPS rating with respect to decreasing efficacy was Nm, Sm, Ec then Bp; Nm, Sm and Ec were very closed while Bp was not effective. These results show the correlation between the antitumor effect in vivo of LPS and their capacity to induce in vitro IL-1 activity, but not between their ability to induce NO production, TNF and IL-6 activities.     

An infant with 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase/isomerase deficiency presenting with typical neonatal hepatitis syndrome: the first Japanese case

We investigated the in vivo effects of thalidomide on the production of tumor necrosis factor-alpha (TNF-alpha). An in vivo systemic release of TNF-alpha occurred after the injection of lipopolysaccharide (LPS) in male ddY mice, and the TNF-alpha serum levels reached 652.2 +/- 75.7 pg/ml 90 min after the injection of LPS (0.3 mg/kg, i. p.). When thalidomide (1, 3, or 6 mg/kg) was administered intraperitoneally 3 h before the injection of LPS (0.3 mg/kg, i. p.), thalidomide markedly enhanced LPS-induced TNF-alpha release in a dose-dependent manner. The TNF-alpha serum levels at 90 min were 640 +/- 58.6, 1985 +/- 132.6, and 2795 +/- 203.5 pg/ml, respectively, compared to 628.6 +/- 64.4 pg/ml in mice treated with LPS-alone. Pretreatment with a single injection of thalidomide (1, 3, or 6 mg/kg, i. p.) dose-dependently increased the subsequent mortality caused by a challenge with LPS (15 mg/kg, i. p.), a dose that caused death in 10% of the control mice. We conclude that thalidomide enhances in vivo TNF-alpha secretion and the lethality of LPS in mice.     

Differential suppression of dialysis patients' lymphocyte IFN-gamma production by glucocorticoids and cyclosporine

IFN-gamma is a potent pro-inflammatory cytokine involved in the immunologic rejection of transplanted organs. Having previously demonstrated differential suppressive effects of methylprednisolone (MP), prednisolone (P) and cyclosporine (CsA) on dialysis patients' lymphocyte proliferative responses to phytohaemagglutinin (PHA), we studied the effects of these drugs on dialysis patients' lymphocyte IFN-gamma production during mitogenic and allogeneic (MLR) stimulation. The mean +/- SEM 50% inhibitory concentration (ng/ml) on cell proliferation was significantly lower for MP than P in PHA-stimulated haemodialysis (HD) patients' (35 +/- 7 vs 152 +/- 25, P < 0.001) and peritoneal dialysis (PD) patients' (35 +/- 11 vs 134 +/- 33, P = 0.001) cultures and in HD patients' MLR cultures (15 +/- 3 vs 48 +/- 9, P < 0.001). The mean +/- SEM fractional responses (PHA or MLR + drug/PHA or MLR) in culture supernatant IFN-gamma concentrations were significantly lower with 10(-7) M concentrations of MP than P in HD (0.19 +/- 0.05 vs 0.31 +/- 0.06, P = 0.01) and PD (0.30 +/- 0.11 vs 0.46 +/- 0.11, P < 0.05) PHA cultures and in HD MLR cultures (0.15 +/- 0.04 vs 0.28 +/- 0.07, P = 0.01). CsA (400 ng/ml) alone not only caused less than 50% inhibition of IFN-gamma production in 15/27 HD PHA, 6/14 PD PHA and 4/13 HD MLR cultures, but actually stimulated it in 9 HD and 5 PD PHA cultures. The results suggest that: (1) MP has greater immunosuppressive potential than P for renal transplant recipients; (2) the stimulation of IFN-gamma by CsA in some patients could be harmful in patients with initial allograft dysfunction; and (3) pre-transplant in-vitro assessment of recipients' PBMC responsiveness to glucocorticoids and CsA may help individualize the post-transplant immunosuppressive regimen.     

Regulated production of type I collagen and inflammatory cytokines by peripheral blood fibrocytes

We recently described a novel population of blood-borne cells, termed fibrocytes, that display a distinct cell surface phenotype (collagen+/CD13+/CD34+/CD45+), rapidly enter sites of tissue injury, and contribute to scar formation. To further characterize the role of these cells in vivo, we examined the expression of type I collagen and cytokine mRNAs by cells isolated from wound chambers implanted into mice. Five days after chamber implantation, CD34+ fibrocytes but not CD14+ monocytes or CD90+ T cells expressed mRNA for type I collagen. Fibrocytes purified from wound chambers also were found to express mRNA for IL-1beta, IL-10, TNF-alpha, JE/MCP, MIP-1alpha, MIP-1beta, MIP-2, PDGF-A, TGF-beta1, and M-CSF. The addition of IL-1beta (1-100 ng/ml), a critical mediator in wound healing, to fibrocytes isolated from human peripheral blood induced the secretion of chemokines (MIP-1alpha, MIP-1beta, MCP-1, IL-8, and GRO alpha), hemopoietic growth factors (IL-6, IL-10, and macrophage-CSF), and the fibrogenic cytokine TNF-alpha. By contrast, IL-1beta decreased the constitutive secretion of type I collagen as measured by ELISA. Additional evidence for a role for fibrocytes in collagen production in vivo was obtained in studies of livers obtained from Schistosoma japonicum-infected mice. Mouse fibrocytes localized to areas of granuloma formation and connective matrix deposition. We conclude that fibrocytes are an important source of cytokines and type I collagen during both the inflammatory and the repair phase of the wound healing response. Furthermore, IL-1beta may act on fibrocytes to effect a phenotypic transition between a repair/remodeling and a proinflammatory mode.     

Erratum to "Immunocytochemical detection of cytokines and chemokines in Langerhans cells and in vitro derived dendritic cells"

We have developed a direct immunocytochemical technique to identify cytokine and chemokine production in epidermal Langerhans cells (LC) and in vitro derived CD14-, CD1a+, CD83+, CD40+ dendritic cells (DC) at the single cell level. Formaldehyde fixation combined with saponin permeabilization preserved cellular morphology and generated a characteristic juxtanuclear staining signal due to the accumulation of cytokine to the Golgi organelle. This approach was used for the assessment of TNF-alpha, IL-6, IL-8, IL-10, IL-12, GM-CSF, MIP-1alpha, MIP-1beta and RANTES producing cells. In contrast, a diffuse cytoplasmic staining was evident for IL-1ra, IL-1alpha and IL-1beta production. IL-1ra and IL-1alpha were expressed in 10-25% of unstimulated cultured cells, while all the other cytokines were undetectable. IL-1ra, IL-1alpha and IL-1beta were also the dominating cytokines, expressed in up to 85% of the DC, after 3 h of LPS stimulation. A significantly lower number of cells (0-5%) synthesized TNF-alpha, IL-6, IL-10, IL-12 and GM-CSF. The incidence of chemokine producing cells (IL-8, RANTES, MIP-1alpha, MIP-1beta) peaked 10 h after LPS stimulation in up to 60% of the DC. Both immature CD83- and mature CD83+ DC as well as LC had a similar cytokine production pattern. Thus, in comparison to monocytes, LPS stimulation of DC generated a lower incidence of TNF-alpha, IL-6, IL-10 and IL-12 producing cells while IL-1 was expressed in a comparable number of cells.     

In vitro IL-1 beta and TNF-alpha release from THP-1 monocytes in response to metal ions

OBJECTIVES: Previous studies have shown that biomaterials can activate macrophages to produce cytokines and promote an inflammatory response. Although the toxicity of many metal ions has been extensively investigated, little is known about the ability of these ions to alter cytokine release from macrophages. Yet the release of these ions from biomaterials has been well documented. Previous studies indicated that alterations in cytokine release might be expected because metal ions alter protein production in macrophages at sub-toxic concentrations. Thus, the hypothesis of this study was that metal ions can alter the secretion of cytokines from macrophages at sub-toxic concentrations. METHODS: The release of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) from macrophages was investigated when the macrophages were exposed to metal ions, with or without lipopolysaccharide (LPS), a component of dental plaque. Human THP-1 macrophages were exposed to ions of Ag, Au, Cu, Hg, and Ni for 24 h. In half of the cultures, LPS was added for the last 4 h. The release of IL-1 beta and TNF-alpha into the medium was measured using enzyme-linked immunosorbent assays. ANOVA and Tukey multiple comparison intervals were used to compare the various experimental conditions. RESULTS: None of the metal ions elevated the IL-1 beta or TNF-alpha levels after 24 h, but Ni ions significantly elevated the IL-1 beta and TNF-alpha levels after 72 h. With LPS added, Ag, Cu, and Ni significantly amplified the LPS-induced production of IL-1 beta but only Ni amplified the TNF-alpha response. These alterations in cytokine response occurred with metal ion concentrations which have been previously shown to be released from dental alloys in vitro and in vivo. SIGNIFICANCE: It appeared plausible that macrophage-cytokine mediated inflammatory responses may be altered by the presence of some metal ions in tissues, particularly Ni.     

The influence of antibodies to TNF-alpha and IL-1beta on haemodynamic responses to the cytokines, and to lipopolysaccharide, in conscious rats

Male, Long Evans rats (350-450 g) were anaesthetized and had pulsed Doppler probes and intravascular catheters implanted to allow monitoring of regional (renal, mesenteric and hindquarters) haemodynamics in the conscious state. Our main objectives were to:- assess the effects of administering human recombinant tumour necrosis factor (TNF)-alpha and human recombinant interleukin-1 (IL-1)beta, alone and together; determine the influence of pretreatment with a mixture of antibodies to TNF-alpha and IL-1beta on responses to co-administration of the cytokines; ascertain if pretreatment with a mixture of the antibodies to TNF-alpha and IL-1beta had any influence on the responses to lipopolysaccharide (LPS). TNF-alpha (10, 100 and 250 microg kg(-1), in separate groups, n=3, 9 and 8, respectively) caused tachycardia (maximum delta, +101+/-9 beats min(-1)) and modest hypotension (maximum delta, -10+/-2 mmHg), accompanied by variable changes in renal and mesenteric vascular conductance, but clear increases in hindquarters vascular conductance; only the latter were dose-related (maximum delta, +6+/-6, +27+/-9, and +61+/-12% at 10, 100 and 250 microg kg(-1), respectively). IL-1beta (1, 10, and 100 microg kg(-1) in separate groups, n = 8, 8 and 9, respectively) evoked changes similar to those of TNF-alpha (maximum delta heart rate, +69+/-15 beats min(-1); maximum delta mean blood pressure, -14+/-2 mmHg; maximum delta hindquarters vascular conductance, +49+/-17%), but with no clear dose-dependency. TNF-alpha (250 microg kg(-1)) and IL-1beta (10 microg kg(-1)) together caused tachycardia (maximum delta, +76+/-15 beats min(-1)) and hypotension (maximum A, -24+/-2 mmHg) accompanied by increases in renal, mesenteric and hindquarters vascular conductances (+52+/-6%, +23+/-8%, and +52+/-11%, respectively). Thereafter, blood pressure recovered, in association with marked reductions in mesenteric and hindquarters vascular conductances (maximum delta, -50+/-3% and -58+/-3%, respectively). Although bolus injection of LPS (3.5 mg kg(-1)) caused an initial hypotension (maximum delta, -27+/-11 mmHg) similar to that seen with co-administration of the cytokines, it did not cause mesenteric or hindquarters vasodilatation, and there was only a slow onset renal vasodilatation. The recovery in blood pressure following LPS was less than after the cytokines, and in the former condition there was no mesenteric vasoconstriction. By 24 h after co-administration of TNF-alpha and IL-1beta or after bolus injection of LPS, the secondary reduction in blood pressure was similar (-16+/-2 and -13+/-3 mmHg, respectively), but in the former group the tachycardia (+117+/-14 beats min(-1)) and increase in hindquarters vascular conductance (+99+/-21%) were greater than after bolus injection of LPS (+54+/-16 beats min ' and +439%, respectively). Pretreatment with antibodies to TNF-alpha and IL-1beta (300 mg kg(-1)) blocked the initial hypotensive and mesenteric and hindquarters vasodilator responses to co-administration of the cytokines subsequently. However, tachycardia and renal vasodilatation were still apparent. Premixing antibodies and cytokines before administration prevented most of the effects of the latter, but tachycardia was still present at 24 h. Pretreatment with antibodies to TNF-alpha and IL-1beta before infusion of LPS (150 microg kg(-1) h(-1) for 24 h) did not affect the initial fall in blood pressure, but suppressed the hindquarters vasodilatation and caused a slight improvement in the recovery of blood pressure. However, pretreatment with the antibodies had no effect on the subsequent cardiovascular sequelae of LPS infusion. the results indicate that although co-administration of TNF-alpha and IL-1beta can evoke cardiovascular responses which, in some respects, mimic those of LPS, and although antibodies to the cytokines can suppress most of the cardiovascular effects of the cytokines, the antibodies have little influence on the haemodynamic responses to LPS, possibly because, during infusion of LPS, the sites of production and local action of endogenous cytokines, are not accessible to exogenous antibodies.     

Pentoxifylline inhibits TNF-alpha production from human alveolar macrophages

Tumor necrosis factor-alpha (TNF-alpha) is an important proinflammatory cytokine. Recently, pentoxifylline (POF) has been shown to suppress the synthesis of TNF-alpha from lipopolysaccharide (LPS)-stimulated human monocytes in cell cultures and in vivo. The aim of this study was to investigate whether POF-induced suppression of TNF-alpha secretion affects peripheral blood monocytes (PBM) and alveolar macrophages (AM) equally, and whether POF is able to suppress the spontaneous TNF-alpha production from AM in pulmonary sarcoidosis in vitro. In seven patients without interstitial lung disease we studied the effect of POF on LPS-stimulated PBM and AM cultured for 24 h. In six patients with sarcoidosis we investigated the effect of POF on the enhanced spontaneous TNF-alpha production by AM in vitro. POF induced a dose-dependent suppression of the LPS-stimulated TNF-alpha production which was not different for PBM and AM, respectively. In sarcoidosis, POF inhibited the spontaneous TNF-alpha production of AM at 0.1 mM by 91% and at 1 mM by 98%. In conclusion, POF inhibits LPS-induced TNF-alpha production from PBM and AM to a similar extent and can also inhibit the exaggerated spontaneous TNF-alpha production from AM in sarcoidosis in vitro. This may be the basis for further clinical trials to evaluate POF as an immunotherapeutic agent in sarcoidosis.     

Effect of calcitriol on the production of T-cell-derived cytokines in psoriasis

Although the use of vitamin D analogues in the treatment of psoriasis has been an important new development, the mechanisms of action of these drugs are not fully understood. Psoriasis results from hyperproliferation of keratinocytes, and various studies attribute a crucial role to the locally infiltrating T lymphocytes. In an attempt to add to the understanding of the mechanisms of calcitriol therapy, we determined the effect of this drug on T cells by studying its effect on proliferation and on the production of various cytokines by T-cell clones prepared from psoriatic skin after non-specific activation with the combination of phytohaemagglutinin (PHA) and phorbol myristate acetate (PMA). The addition of increasing doses (10(-9)-10(-5) mol/l) of calcitriol to these T cells resulted in a dose-dependent inhibition in lymphocyte proliferation and in production of the type 1 cytokines IFN-gamma and IL-2, the type 2 cytokines IL-4 and IL-5. The general cytokines TNF-alpha and GM-CSF were not significantly inhibited. These data suggest that calcitriol is involved in the treatment of psoriasis via inhibition of the expansion, and cytokine production, of skin-infiltrating T lymphocytes.     

Mg2+ coordination in catalytic sites of F1-ATPase

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) and inflammatory cytokines on regulation of interleukin-6 (IL-6) production by human gingival fibroblasts (HGF). The HGF cell lines used in this study, H-CL and F-CL, were established by the explant technique from healthy gingival tissue. Cultured cells were grown to confluency and incubated with various concentrations of LPS from Escherichia coli or Porphyromonas gingivalis or with the recombinant human cytokine tumor necrosis factor alpha (TNF-alpha), IL-1alpha, or IL-1beta. Culture supernatants were collected at various times and assessed for IL-6 production by enzyme-linked immunosorbent assay. Total RNA was isolated from the harvested cells and used to assess levels of IL-6 mRNA by the RNase protection assay. Both LPS preparations induced IL-6 production (1 to 4 ng of IL-6 per ml) by both HGF cell lines. Although TNF-alpha stimulated IL-6 production by HGF, > 10-fold-larger amounts were induced with IL-1alpha and IL-1beta. Furthermore, the addition of both IL-1alpha and TNF-alpha to cultured cells resulted in approximately 600- to 800-fold-higher levels of IL-6 than seen in control cultures, suggesting that these cytokines synergistically induced IL-6 production by HGF. IL-6 message in cultured cells was upregulated 20-fold by TNF-alpha, 1,000-fold by IL-1alpha and IL-1beta, and 1,400-fold by IL-1alpha plus TNF-alpha. IL-1alpha and TNF-alpha alone upregulate IL-6 production in a dose- and time-dependent fashion. The addition of IL-1alpha and TNF-alpha to cultured HGF cells resulted in a synergistic induction of IL-6 after 8 h of incubation and when greater than 10 pg of this combination per ml was used. Our studies show that inflammatory cytokines are hundreds of times more potent than LPS in stimulating IL-6 production by HGF.     

Mutations of Arabidopsis in potential transduction and response components of the phototropic signaling pathway

IL-1 plays an important role in the pathophysiologic responses to infection and inflammation, in part by mediating its own production and that of other proinflammatory cytokines. However, the relative contribution of IL-1 alpha and IL-1 beta to the inflammatory response has not been well clarified. Using IL-1 beta-deficient (IL-1 beta -/-) mice, we investigated the specific role of IL-1 beta in the in vivo and in vitro response to LPS. No differences between IL-1 beta +/+ and IL-1 beta -/- mice were observed in circulating levels for IL-1 alpha, IL-6, or TNF-alpha after the systemic administration of either a low (5 micrograms/kg) or high (5 mg/kg) dose of LPS. IL-1 beta -/- mice also had a normal response to LPS in terms of activation of the hypothalamus-pituitary-adrenal axis, hypoglycemia, serum amyloid A production, and anorexia. IL-1 beta -/- mice were normally sensitive to the lethal effect of LPS and were protected against LPS toxicity when pretreated with low-dose LPS. However, in vitro, peritoneal macrophages from IL-1 beta -/- mice stimulated with LPS produced significantly less IL-1 alpha than macrophages from IL-1 beta +/+ mice (p < 0.05). No differences in IL-6 or TNF-alpha synthesis were observed between macrophages from IL-1 beta +/+ and IL-1 beta -/- mice. In summary, our results suggest that either IL-1 beta is not essential for the in vivo systemic response to LPS or that its role can be fulfilled by other cytokines with overlapping activities.