Production of pro- and anti-inflammatory cytokines by monocytes from patients with paracoccidioidomycosis

Monocytes and macrophages can produce a large repertoire of cytokines and participate in the pathogenesis of granulomatous diseases. We investigated the production of pro- and anti-inflammatory cytokines by monocytes from patients with active paracoccidioidomycosis. Peripheral blood monocytes from 37 patients and 29 healthy controls were cultivated with or without 10 microg/ml of lipopolysaccharide (LPS) for 18 h at 37 degrees C, and the cytokine levels were determined in the culture supernatants by enzyme immunoassay. The results showed that the endogenous levels of tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, IL-8, IL-10 and transforming growth factor beta detected in the supernatant of patient monocytes cultivated without stimulus were significantly higher than those produced by healthy controls. These data demonstrated that monocytes from patients with active paracoccidioidomycosis produce high levels of cytokines with both inflammatory and anti-inflammatory activities. However, patient monocytes produced significantly lower TNF-alpha and IL-6 levels in response to LPS when compared to normal subjects, suggesting an impairment in their capacity to produce these cytokines after LPS stimulation. Concentrations of IL-1beta, IL-8 and IL-10 in cultures stimulated with LPS were higher in patients than in controls. These results suggest that an imbalance in the production of pro- and anti-inflammatory cytokines might be associated with the pathogenesis of paracoccidioidomycosis.     

IL-10 and toll-like receptor-4 polymorphisms and the in vivo and ex vivo response to endotoxin

To determine to what extent lipopolysaccharide-induced IL-10 production capacity is determined by polymorphisms in toll-like receptor-4 (TLR4) and the IL-10 promoter region, we measured in vivo IL-10 and TNF-alpha production in patients undergoing elective cardiopulmonary bypass surgery, a major surgical trauma associated with ischemia-reperfusion injury that triggers an endotoxemia and profound inflammatory response in most patients. Ex vivo the IL-10 and TNF-alpha production was measured in a whole blood stimulation assay, using 3 LPS concentrations. Positive correlations were found between TNF-alpha and IL-10 production ex vivo, upon stimulation with each of the LPS concentrations. Also, the estimated TNF-alpha and IL-10 EC50, and TNF-alpha(max) and IL-10max were positively correlated (r = 0.203; p = 0.023 and r = 0.287; p = 0.001, respectively), indicating that these parameters describing LPS sensitivity and maximal production capacity, respectively, can be estimated by measuring either TNF-alpha or IL-10. Interleukin-10 concentrations in patients experiencing endotoxemia in vivo negatively correlated with the IL-10 levels produced upon stimulation with 1000 ng/mL LPS as well as the estimated IL-10max ex vivo. In vivo, a positive correlation between the TNF-alpha concentration at time-point 2 and the IL-10 concentration at time-point 3 was found, consistent with an important contribution of the magnitude of TNF-alpha release upon the subsequent IL-10 production. Carriers of the IL-10 promoter -1330G, -1082A, -819T, -592A (GATA) haplotype had lower IL-10 production ex vivo upon stimulation with 10 and 100 ng/mL LPS and higher EC50 values (the estimated LPS concentration at which 50% of the maximal IL-10 response is reached) as compared to carriers of the other haplotypes combined, indicating decreased LPS sensitivity ex vivo. These individuals did not differ from the others in interleukin-10 production capacity upon stimulation with a high LPS concentration (i.e., 1000 ng/mL) and the estimated IL-10(max) values, were similar, indicating unimpaired maximal IL-10 production capacity ex vivo. Carriers of the IL-10 promoter AGCC haplotype had lower EC50 values as compared to carriers of the other haplotypes combined, indicating increased LPS sensitivity ex vivo. In accordance with this finding, carriers of the AGCC haplotype had higher circulating IL-10 levels in vivo. The common TLR4 polymorphisms (Asp299Gly and Thr399Ile) were associated with slightly higher IL-10 production capacity ex vivo and in vivo, however, this was not statistically significant. Our results indicate that polymorphisms in the proximal IL-10 promoter region are associated with in vivo and ex vivo LPS sensitivity. The contribution to the inter-individual variation, however, is limited since the variation between individuals in LPS sensitivity and IL-10 production capacity can only partly be attributed to these IL-10 promoter polymorphisms.     

Intrinsic capacity of monocytes to produce cytokines ex vivo in patients with acute lymphoblastic leukaemia

Monocytic cytokine profiles of fifteen children with acute lymphoblastic leukaemia (ALL) were included to determine whether malignancy per se contributes to impaired cytokine profiles in vivo and ex vivo. The ex vivo tumour necrosis factor-alpha (TNF-alpha) and interleukin 1beta (IL-1beta) production was positively correlated with the monocyte number and with the number of intracellular TNF-alpha or IL-1beta positive cells in lipopolysaccharide (LPS)-stimulated MNC cultures. The mean ex vivo TNF-alpha and IL-1beta production per 1x10(4)monocytes in these cultures was not significantly different in children at diagnosis of ALL, at remission or in controls. High IL-10 plasma levels at diagnosis of ALL had no effect on the ex vivo TNF-alpha and IL-1beta production of monocytes in LPS stimulated MNC cultures. These results show that monocytes of ALL patients have a normal intrinsic capacity to produce cytokines ex vivo. However, the decreased monocyte number is responsible for the lower TNF-alpha and IL-1beta concentrations ex vivo upon LPS stimulation.     

Seasonal variation in whole blood cytokine production after LPS stimulation in normal individuals

We examined seasonal differences in whole blood cytokine production after endotoxin (LPS) stimulation in 17 healthy individuals from an urban area having normal sleep/wakefulness pattern. We used 500 pg/ml of LPS for incubation period of 4 h to stimulate 100 microl of whole blood of the same subjects in June, September, February, and March. We found no differences in the circulating total WBCs and differentials including monocytes between different seasons. We found during September (autumn) a reduced pro-inflammatory cytokine production in terms of TNF-alpha and IL-6 production compared to the other seasons. We also found a reduced anti-inflammatory cytokine production in June (summer) and September (autumn) in terms of IL-10, TNF-RI and TNF-RII compared to February (winter) and March (spring). Our results suggest that in early summer there is a predominating pro-inflammatory cytokine response which is counterbalanced early in autumn. These results may have significant implications in the determination of reference values, in exploration of immune response and inflammatory disease prevalence between different seasons, in determining LPS tolerance (immunoparalysis) and planning clinical trials and immunomodulary therapies. However, the effect of dark/light exposure differences on the circadian periodicity in the responsiveness of immune cells during different seasons should be further investigated.     

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.     

Detection of human P2X7 nucleotide receptor polymorphisms by a novel monocyte pore assay predictive of alterations in lipopolysaccharide-induced cytokine production

The nucleotide receptor P2X(7) is expressed by most leukocytes and initiates signaling events that amplify numerous LPS responses. We tested the hypothesis that loss-of-function polymorphisms in the human P2X(7) gene predispose to the production of an anti-inflammatory mediator balance. Accordingly, we developed a novel P2X(7) pore assay in whole blood that magnifies the activity from wild-type alleles and preserves the gene dosage effect for the 1513 C polymorphism (AA, 69 +/- 4; AC, 42 +/- 4; and CC, 6 +/- 1-fold stimulation). Thirty of 200 healthy individuals were identified as having low P2X(7) pore activity. Seven low pore subjects were 1513 CC, 3 and 11 participants had the other known variants 946 GA and 1729 TA respectively; the remaining 9 volunteers likely have novel polymorphisms. Because platelets are a large source of extracellular ATP during inflammation, whole blood was treated ex vivo with Salmonella typhimurium LPS in the absence of exogenous nucleotides. LPS-stimulated whole blood from individuals in the low pore activity group generated reduced plasma levels of TNF-alpha (p = 0.036) and higher amounts of IL-10 (p < 0.001) relative to the high pore controls. This reduction in the TNF-alpha to IL-10 ratio persisted to at least 24 h and is further decreased by cotreatment with 2-methylthio-ATP. The ability of P2X(7) polymorphisms to regulate the LPS-induced TNF-alpha to IL-10 ratio suggests that 15% of healthy adults may exhibit anti-inflammatory mediator responses during major infectious perturbations of the immune system, which can be predicted by P2X(7) pore activity.     

Interleukin 8 production in whole blood assays: Is interleukin 10 responsible for the downregulation observed in sepsis?

Reduced cytokine production in ex vivo cultures has been regularly reported in patients suffering from sepsis syndrome. Using whole blood assays, we have now demonstrated that in sepsis patients, normal production of IL-8 was achieved with the higher concentration of lipopolysaccharide (LPS; 1 microg/ml) and with heat-killed streptococci, whereas the IL-8 production induced by lower LPS concentration (0.1 microg/ml) was significantly reduced as compared to healthy controls. In contrast, in patients undergoing cardiac surgery associated with cardio-pulmonary bypass, a group of patients with inflammation in the absence of infectious insult, none of the studied IL-8 productions were affected. Among the various anti-inflammatory cytokines known to regulate IL-8 production which we tested (i.e. IL-4, IL-10, IL-13, TGF-beta), IL-10 was the most active inhibitory cytokine in whole blood assays performed with blood samples from healthy subjects. However, its activity was not influenced by the amounts of LPS used. In addition, IL-10 also inhibited the heat-killed streptococci-induced IL-8 production and was the only cytokine to inhibit the release of IL-8 when TNF was added to LPS. It is worth noting that IL-13 which also inhibited the heat-killed streptococci-induced IL-8 production, failed to do so when the TNF production was analysed. Together, these data suggest that while circulating IL-10 in septic patients may be responsible for the hyporeactivity of circulating leukocytes, its presence is not sufficient to explain the observed dysregulation which occurs in septic patients.     

Whole blood pro-inflammatory cytokines and adhesion molecules post-lipopolysaccharides exposure in hyperbaric conditions

Hyperbaric oxygen (HBO) is a therapeutic intervention with applications in a large variety of diseases, including traumatic injuries and acute or chronic infections. The presence of pro-inflammatory cytokines regulates certain factors including adhesion molecules, which play a significant role in HBO effects. We have investigated the effect of HBO on pro-inflammatory cytokine release [tumor necrosis factor-alpha (TNF-alpha), interleukin 6 and 8 (IL-6 and IL-8)], and the regulation of adhesion molecules [soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular adhesion molecule (sVCAM)] after lipopolysaccharide (LPS) stimulation in 16 healthy individuals, originating from an urban area. A total number of 64 samples were treated, divided into four groups: Group A: not stimulated with LPS and not exposed to HBO. Group B: stimulated with LPS and not exposed to HBO. Group C: not stimulated with LPS and exposed to HBO. Group D: stimulated with LPS and exposed to HBO. The LPS stimulation dose was 100 pg\ml for 0.1 ml whole blood diluted 1:10. After incubation, samples were exposed to HBO with 100% O2 at 2.4 atmospheres absolute (ATA) for 90 min. TNF-alpha, IL-6, IL-8 and sICAM-1, sVCAM levels were determined in culture supernatant, with ELISA. We observed an enhanced effect of LPS stimulation following exposure to HBO, which caused an increase in cytokine production (TNF-alpha, IL-6, IL-8), a reduction in sICAM, and no change to sVCAM, while their levels without stimulation remained almost invariable. The decrease in sICAM levels could be related to the increased levels of IL-8, as the production of this chemokine is involved in the regulation of adhesion molecules.     

The new generation synthetic reconstituted surfactant CHF5633 suppresses LPS-induced cytokine responses in human neonatal monocytes

BackgroundNew generation synthetic surfactants represent a promising alternative in the treatment of respiratory distress syndrome in preterm infants. CHF5633, a new generation reconstituted agent, has demonstrated biophysical effectiveness in vitro and in vivo. In accordance to several well-known surfactant preparations, we recently demonstrated anti-inflammatory effects on LPS-induced cytokine responses in human adult monocytes. The present study addressed pro- and anti-inflammatory effects of CHF5633 in human cord blood monocytes.MethodsPurified neonatal CD14⁺ cells, either native or simultaneously stimulated with E. coli LPS, were exposed to CHF5633. TNF-α, IL-1β, IL-8 and IL-10 as well as TLR2 and TLR4 expression were analyzed by means of real-time quantitative PCR and flow cytometry.ResultsCHF5633 did not induce pro-inflammation in native human neonatal monocytes and did not aggravate LPS-induced cytokine responses. Exposure to CHF5633 led to a significant decrease in LPS-induced intracellular TNF-α protein expression, and significantly suppressed LPS-induced mRNA and intracellular protein expression of IL-1β. CHF5633 incubation did not affect cell viability, indicating that the suppressive activity was not due to toxic effects on neonatal monocytes. LPS-induced IL-8, IL-10, TLR2 and TLR4 expression were unaffected.ConclusionOur data confirm that CHF5633 does not exert unintended pro-apoptotic and pro-inflammatory effects in human neonatal monocytes. CHF5633 rather suppressed LPS-induced TNF-α and IL-1β cytokine responses. Our data add to previous work and may indicate anti-inflammatory features of CHF5633 on LPS-induced monocyte cytokine responses.     

Ex vivo induction of cytokines by mould components in whole blood of atopic and non-atopic volunteers

We investigated the time-course release of IL-1beta and IL-8 protein as well as the steady state mRNA level of their genes in human whole blood after stimulation with LPS, beta-1,3-D-glucan and mould extracts. We compared the response of 10 non-atopic and 10 atopic individuals. In parallel, cytokine protein release and the corresponding steady state mRNA level was determined by the standard ELISA and real-time on-line RT-PCR methods, respectively. Glucan induced the highest level of IL-1beta mRNA and protein release after 3 h. IL-8 was induced at 3 h after glucan, but not after LPS, induction, which indicates different induction pathways. At the time-points found to elicit the optimal cytokine response significantly higher basal cytokine mRNA levels and significantly lower LPS induced cytokine mRNA levels were observed in the non-atopic group. Generally, mould components induced cytokine mRNA steady state to lower levels in the atopics compared to the non-atopics. In contrast, no differences were found between the two groups in their capacity to induce cytokine protein release. These findings persisted after correction for the percentage of mononuclear cells. The data supported our hypothesis that "exhaustion" of the atopic immune system elicits lower basal cytokine mRNA levels and that analysis of cytokine gene expression has the potential to differentiate between non-atopic and atopic individuals.     

Role of alpha(2)-macroglobulin in fever and cytokine responses induced by lipopolysaccharide in mice

Alpha(2)-macroglobulin (alpha(2)M) is not only a proteinase inhibitor in mammals, but it is also a specific cytokine carrier that binds pro- and anti-inflammatory cytokines implicated in fever, including interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha). To define the role of alpha(2)M in regulation of febrile and cytokine responses, wild-type mice and mice deficient in alpha(2)M (alpha(2)M -/-) were injected with lipopolysaccharide (LPS). Changes in body temperature as well as plasma levels of IL-1beta, IL-6, and TNF-alpha and hepatic TNF-alpha mRNA level during fever in alpha(2)M -/- mice were compared with those in wild-type control mice. The alpha(2)M -/- mice developed a short-term markedly attenuated (ANOVA, P < 0.05) fever in response to LPS (2.5 mg/kg ip) compared with the wild-type mice. At 1.5 h after injection of LPS, the plasma concentration of TNF-alpha, but not IL-1beta or IL-6, was significantly lower (by 58%) in the alpha(2)M -/- mice compared with their wild-type controls (ANOVA, P < 0.05). There was no difference in hepatic TNF-alpha mRNA levels between alpha(2)M -/- and wild-type mice 1.5 h after injection of LPS. These data support the hypotheses that 1) alpha(2)M is important for the normal development of LPS-induced fever and 2) a putative mechanism of alpha(2)M involvement in fever is through the inhibition of TNF-alpha clearance. These findings indicate a novel physiological role for alpha(2)M.     

Biphasic production of IL-8 in lipopolysaccharide (LPS)-stimulated human whole blood. Separation of LPS- and cytokine-stimulated components using anti-tumor necrosis factor and anti-IL-1 antibodies.

TNF, IL-1, and IL-6 are integral components of the cytokine cascade released in the response to inflammatory stimuli such as LPS. IL-8 is produced both in response to LPS as well as TNF and IL-1. The early, local production of TNF and IL-1 may therefore contribute to the subsequent expression of IL-8. This hypothesis was tested using LPS-stimulated human whole blood as an ex vivo model of local cytokine production. The production of TNF, IL-1 alpha, IL-1 beta, IL-6, and IL-8 was found to be responsive to a wide range of LPS concentrations (0.1 ng/ml-10 micrograms/ml). These cytokines were first detected between 1 to 4 h post-LPS stimulation, and reached plateau levels after 6 to 12 h. IL-8, however, also displayed a secondary wave of production, with the levels again increasing between 12 to 24 h. The IL-8 present in the plasma after LPS stimulation was biologically active, as assessed by neutrophil chemotaxis. In further studies, addition of anti-TNF and anti-IL-1 neutralizing antibodies, alone and in combination, to LPS-stimulated blood resulted in nearly complete ablation of the secondary phase of IL-8 synthesis at both the levels of protein and mRNA, while leaving the first, LPS-mediated phase of IL-8 synthesis unaffected. This model of cytokine production in human whole blood may reflect the sequence of events in a localized environment of inflammation where both a primary stimulus and the induced early cytokine mediators may serve to elicit multiple, temporally distinct phases of IL-8 production.     

Flow cytometrical determination of regulatory cytokines (IL-10, IL-12) and circulating dendritic cell cytokines in allergic asthmatic children

Interleukin (IL)-10 and IL-12 have been suggested to be key regulators in the pathogenesis of allergic asthma. Several of the secretion products of dendritic cells (DC), such as IL-12, IL-10, IL-1beta and TNF-alpha, are considered to play a role in allergic asthma. This study compares the production of IL-10 and IL-12 in allergic asthmatic children (n = 17) and controls (n = 14) by measuring their extracellular secretion in whole blood samples after stimulation, using a microsphere-based immunoassay. Additionally, we assessed intracellular production of IL-1beta, TNF-alpha, IL-12 and IL-10 by circulating DC in stimulated whole blood samples of asthmatic and healthy children. The concentration of IL-10 in the supernatants of LPS-stimulated whole blood was significantly lower in allergic asthmatic children as compared to healthy children (463 (207-768) vs 881 (364-2626) pg/mL; p = 0.005). When a combined LPS and IFN-gamma stimulation was used, IL-10 production decreased significantly as compared to LPS alone, especially in healthy children. Consequently, no difference in IL-10 production after LPS/IFN-gamma stimulation was found between healthy and allergic children. In contrast to isolated LPS stimulation, stimulation with LPS/IFN-gamma induced higher IL-12 production; allergic asthmatic children showed a significantly lower IL-12 secretion after LPS/IFN-gamma stimulation as compared to healthy children (20 (5-247) vs 208 (7-775) pg/mL; p=0.03). Moreover, the number of IL-12 producing CD11c-positive DC (DC1) tended to be lower in asthmatic children compared to healthy children (0.05 (0.00-0.45) vs 0.27 (0.00-0.83) 10(6)/L) and correlated with the extracellular release of IL-12 in asthmatic children (r = 0.65; p = 0.016). The number of IL-1beta and TNF-alpha producing CD11c-positive DC (DC1) was comparable between healthy and asthmatic children. We hypothesize that the decreased production of IL-10 and IL-12 is responsible for Th2 polarized responses in allergic asthmatic children.     

Ex vivo lipopolysaccharide (LPS)-induced TNF-alpha, IL-1beta, IL-6 and PGE2 secretion in whole blood from Type 1 diabetes mellitus patients with or without aggressive periodontitis

Several studies have demonstrated that diabetes is a risk factor for developing periodontal disease, increasing its prevalence and severity. Furthermore, periodontitis may impair the metabolic control and adequate treatment of diabetic patients. LPS from Gram-negative bacteria penetrates the periodontal tissues and subsequently recruits and activates immune cells. Progression to severe periodontitis with loss of supporting structures is mediated by several factors, including secretion of a broad spectrum of inflammatory and destructive (PGE2). mediators such as cytokines (TNF-alpha, IL-1b and IL-6), chemokines (IL-8) and prostaglandin E2. The aim of this work is to investigate differences in the TNF-a, IL-1b and IL-6 expression and prostaglandin E2 (PGE2) release in blood from diabetic patients with and without aggressive periodontitis (AP) stimulated with lipopolysaccharide (LPS). For this purpose we recruited 29 Type 1 diabetes mellitus (DM) patients, 14 with AP and 15 without AP. Fourteen healthy individuals formed the control group. For cytokine expression and PGE2 secretion, an ex vivo whole blood culture system was used. Cytokines and PGE2 were detected by commercial immunometric assays. A wide range of inter-individual variability in spontaneous and LPS-induced TNF-alpha, IL-1b and IL-6 levels in patient groups and controls was found. The mean of spontaneous and LPS-induced TNF-alpha and IL-1b levels did not differ significantly (p > 0.5) when patients were compared to control individuals. Although not significant, the spontaneous TNF-alpha, IL-1b and IL-6 levels in the group of Type 1 DM with AP were higher than in controls, while in diabetic patients without AP, these values were depressed in comparison with controls. In both groups of patients, the means of LPS-induced IL-6 levels were higher than the controls but the differences observed were not significant (p = 0.07). However, the LPS-induced PGE2 levels varied significantly when all groups were compared (p = 0.007). The means of LPS-induced PGE2 levels for Type 1 diabetic patients with AP (p = 0.0009) and without AP (p = 0.024) were significantly higher than the levels observed for healthy controls. Finally, we conclude that Type 1 diabetic patients with or without AP did not express higher LPS-induced TNF-a, IL-1b and IL-6 levels than controls. However, the PGE2 levels released were significantly higher than those detected in controls.     

Effect of catecholamines on intracellular cytokine synthesis in human monocytes.

Proinflammatory cytokines produced by monocytes, like Interleukin-6 (IL-6), Interleukin-8 (IL-8), and tumor necrosis factor (TNF-alpha) are known for their pivotal role in the initiation of the inflammatory response following cardiopulmonary bypass (CPB). Catecholamines like epinephrine (Epi) and norepinephrine (Nor) are often necessary to stabilize the cardiac function in the early postoperative period and may influence the cytokine expression in monocytes. In this study we investigated the effects of Epi and Nor on IL-6, IL-8 and TNF-alpha expression in human monocytes stimulated with lipopolysaccharide (LPS) in whole blood, analyzed intracellularly by flow cytometry. Kinetics of intracellular proinflammatory cytokine production and LPS ED(50) were obtained. To simulate different stages of inflammation in vivo, varying concentrations of LPS (0.2 ng/ml, 1 ng/ml and 10 ng/ml) were used for stimulation. After a stimulation with LPS TNF-alpha was the first produced cytokine, followed by IL-8 and IL-6. All cytokines peaked from 3 h to 6 h. Epi and Nor had comparable effects on the expression of IL-6, IL-8 and TNF-a in monocytes. Both inhibited IL-6 and TNF-alpha expression in a concentration dependent manner whereas IL-8 expression remained unchanged. We conclude that monocytes are targets for Epi and Nor concerning their cytokine expression. The inhibiting effects of Nor and Epi were almost identical for all cytokines. Cytokine expression was affected most at low LPS concentrations.     

TNF-alpha promoter, Nod2 and toll-like receptor-4 polymorphisms and the in vivo and ex vivo response to endotoxin

Humans exhibit substantial inter-individual differences in TNF-alpha production upon endotoxin stimulation. To determine to what extent the lipopolysaccharide-induced TNF-alpha production capacity in vivo and ex vivo is determined by polymorphisms in toll-like receptor-4 (TLR4), the TNF-alpha promoter region and Nod2, we screened for two TLR4 polymorphisms, a Nod2 polymorphism and the TNF-alpha promoter polymorphisms. We measured the perioperative endotoxemia and TNF-alpha production and the TNF-alpha production capacity of each patient in a whole-blood stimulation assay using blood drawn before anesthesia, using various LPS concentrations, in patients undergoing elective cardiac surgery. This operation represents a major surgical trauma associated with ischemia-reperfusion injury and triggers an endotoxemia and profound inflammatory response. In vivo TNF-alpha production was positively correlated with the level of endotoxemia after aortic declamping; thus TNF-alpha levels were higher in patients having endotoxemia compared to patients without endotoxemia. This correlation was observed in patients with any of the genotypes studied, and did not differ between the various genotypes. In vivo TNF-alpha levels correlated best with those ex vivo after stimulation with 1000 ng/mL LPS, and the estimated maximal TNF-alpha release capacity. Subjects with the wild-type TLR4 gene had similar levels of TNF-alpha upon LPS stimulation ex vivo as compared with patients carrying Asp299Gly and/or the Thr399Ile TLR4 polymorphism. Our results indicate that polymorphisms in the TLR4 receptor, Nod2 and TNF-alpha promoter region are not strongly associated with in vivo and ex vivo TNF-alpha production capacity upon endotoxin stimulation. This suggests that in this model of natural LPS release, the variation between individuals in TNF-alpha release can only modestly be determined by genetic background (TNF-alpha promoter, Nod2 and TLR4) of the individual.     

Direct stimulation of cytokines (IL-1 beta, TNF-alpha, IL-6, IL-2, IFN-gamma and GM-CSF) in whole blood. I. Comparison with isolated PBMC stimulation.

Production of interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), interleukin 2 (IL-2), interferon gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) after stimulation by lipopolysaccharide (LPS) and phytohemagglutinin (PHA) was studied in 1/10 diluted whole blood (WB) culture and in peripheral blood mononuclear cell (PBMC) culture. Cytokines IL-1 beta, TNF-alpha and IL-6 are preferentially stimulated by LPS whereas IL-2, IFN-gamma and GM-CSF are stimulated by PHA. Combination of 5 micrograms/ml PHA and 25 micrograms/ml LPS gave the most reliable production of the six cytokines studied. IL-1 beta, TNF-alpha and IL-6 represent a homogeneous group of early-produced cytokines positively correlated among themselves and with the number of monocytes in the culture (LeuM3). Furthermore, IL-1 beta was negatively correlated with the number of T8 lymphocytes. IL-2, IFN-gamma and GM-CSF represent a group of late-produced cytokines. Kinetics and production levels of IL-6 and GM-CSF are similar in WB and PBMC cultures. In contrast, production levels of TNF-alpha and IFN-gamma are higher in WB than in PBMC whereas production levels of IL-6 and IL-2 are lower in WB than in PBMC. Individual variation in responses to PHA + LPS was always higher in PBMC cultures than in WB cultures. The capacity of cytokine production in relation to the number of mononuclear cells is higher in WB, or in PBMC having the same mononuclear cell concentration as WB, than in conventional cultures of concentrated PBMC (10(6)/ml). Because it mimics the natural environment, diluted WB culture may be the most appropriate milieu in which to study cytokine production in vitro.