Production of serum amyloid A and C-reactive protein by HepG2 cells stimulated with combinations of cytokines or monocyte conditioned media: the effects of prednisolone.

The hepatic production of the acute phase proteins in response to inflammatory cytokines, and the interaction of corticosteroids within this response, has been the subject of considerable recent research. In this study we have examined the effects of the corticosteroid prednisolone on the production of IL-1 alpha and IL-1 beta by lipopolysaccharide (LPS)-stimulated monocytes, and the ability of the monocyte conditioned media (MOCM) obtained under these conditions to induce human hepatoma HepG2 cells to produce serum amyloid A (SAA) and C-reactive protein (CRP). We also examined the production of SAA and CRP by HepG2 cells exposed to different combinations and concentrations of recombinant human (rh) IL-1 alpha, rhIL-1 beta, rhIL-6, recombinant human tumour necrosis factor-alpha (rhTNF-alpha) and prednisolone. The findings indicate: (i) prednisolone substantially inhibits the production of both IL-1 alpha and IL-1 beta by LPS-stimulated monocytes. The MOCM from prednisolone-treated monocytes induced less SAA and CRP production by HepG2 cells; (ii) IL-1 alpha and IL-1 beta both induced CRP and SAA synthesis by HepG2 cells, but only in the presence of IL-6. IL-1 beta was the more potent inducer for SAA production, but for CRP production IL-1 alpha and IL-1 beta were equivalent; (iii) prednisolone enhances the production of SAA by HepG2 cells, but does not enhance the production of CRP; (iv) TNF-alpha in the presence or absence of IL-6 and/or prednisolone did not induce the production of SAA or CRP by HepG2 cells. These findings offer a tenable solution to a disparate production of SAA compared with CRP in corticosteroid-treated cystic fibrosis (CF) patients.     

Proinflammatory cytokines (IL-6, IL-8), cytokine inhibitors (IL-6sR, sTNFRII) and anti-inflammatory cytokines (IL-10, IL-13) in the pathogenesis of sepsis in newborns and infants.

The levels of the proinflammatory cytokines interleukin 6 (IL-6) and IL-8, and the anti-inflammatory cytokines IL-10 and IL-13 were studied in child patients with sepsis. The changes of the cytokine inhibitors soluble IL-6 receptor and soluble p75 TNF-alpha receptor were also investigated in the patients' sera. An increase of pro- and anti-inflammatory cytokine levels was demonstrated at the time of diagnosis. Pharmacotherapy was accompanied by a decrease of the elevated concentrations of both cytokines and their inhibitors. The time pattern of changes in cytokine and cytokine inhibitor serum concentrations along with the time course of acute phase indices, including procalcitonin and C-reactive protein, allows for an evaluation of the system inflammatory response and may support diagnostic and prognosis methods.     

Acute phase protein changes in antigen-induced mono-articular arthritis in rabbits and mice.

Acute phase protein levels have been measured during the induction and progression of antigen-induced mono-articular arthritis in rabbits and mice. In rabbits there was a short lived elevation in serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) immediately following intra-articular injection which returned to baseline levels 10-12 days after the injection. In BALB/c mice, serum amyloid P-component (SAP) and the third component of complement (C3) were elevated after intra-articular injection, returning towards baseline levels 6 weeks after the injection. The levels of CRP and SAP correlated with the inflammatory changes in the joints during the acute phase of the arthritic response (7 days after intra-articular injection). During the chronic phase the levels of these acute phase proteins bore no relationship to the degree of connective tissue destruction.     

Treatment of cancer patients with endotoxin induces release of endogenous cytokines.

This study sought to determine whether endogenous tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and granulocyte-colony-stimulating factor (G-CSF) were detectable in sera of lipopolysaccharide (LPS)-treated cancer patients. Twenty patients received an intravenous bolus of purified LPS from Salmonella abortus-equi (4.0 ng/kg). Patients were pretreated with ibuprofen (1,600 mg) to prevent constitutional side effects like fever and chills. Serum TNF-alpha levels increased from less than 0.01 ng/ml before treatment up to maximal levels of 21 ng/ml, peaking 1.5 h after LPS injection. Similarly, serum IL-6 concentrations increased from less than 0.01 to 11 ng/ml, but peak levels were obtained 30 min later than TNF-alpha. Circulating G-CSF appeared still later than TNF-alpha and IL-6. It was detectable within 3 h and peaked 6 h after LPS injection. Parallel to the release of the above cytokines a marked increase in granulocyte counts was observed. In all patients administration of LPS led to an acute-phase response as measured by C-reactive protein.     

Early time course of the acute phase protein response in man.

The rate at which the acute phase protein response occurred after both major and minor surgery was explored. Increases in the plasma concentration of C-reactive protein (CRP), alpha-1-acid glycoprotein (alpha 1 AG) and fibrinogen were not detected until 6-8 h after the initial incision. The peak concentration of CRP occurred at 48 h and that of fibrinogen at 96 h; alpha 1 AG concentrations rose rapidly until 48 h followed by little change until about 120 h. Although there was widespread variation in the concentrations of individual proteins in patients, severity of injury did not seem to have a significant effect on the time course of the change. Plasma cortisol concentration and the total white blood cell count (WBC) reached their peaks before the acute phase proteins, cortisol at 6 h and WBC at 12 h.     

Expression of terminal complement components by human keratinocytes

Human keratinocytes are important constituents of the skin immune system. They produce several cytokines, chemokines as well as some complement proteins. As regards soluble complement proteins, so far keratinocytes have been shown to synthesize only C3, factor B, factor H and factor I. Synthesis and regulation of synthesis of other complement proteins has not yet been studied. Here we studied the synthesis of terminal complement components, C5-C9 by human keratinocytes. We also studied the regulation of terminal complement synthesis in keratinocytes by several cytokines, namely, IL-1alpha, IL-2, IL-6, TGF-beta1, TNF-alpha, and IFN-gamma. Human keratinocytes constitutively expressed C5, C7, C8gamma and C9 mRNA but not C6, C8alpha and C8beta mRNA. They released C7 and C9, but not C5, C6 and C8. None of the cytokines tested had any influence on the synthesis of terminal components except TNF-alpha, which strongly upregulated C9 production. In conclusion, we demonstrate that keratinocytes are capable of synthesizing some of the terminal complement components and that the synthesis of C9 is regulated by TNF-alpha.     

Proinflammatory circulating molecules in peripheral arterial disease

Peripheral arterial disease (PAD) affects about 5% of the elderly population in the western world. It has been reported that PAD is associated with elevated plasma levels of the inflammatory markers. The goal of this review is to describe which proinflammatory molecules may play a role in PAD development, C-reactive protein, fibrinogen, pro-inflammatory cytokines, adhesion molecules and matrix metalloproteinases have been reported to be involved. High serum levels of both C-reactive protein and fibrinogen have been shown to be significantly associated with increasing severity of PAD. Among cytokines, IL-6 is one of the most studied in PAD. IL-6 is well recognized for its role in the acute phase inflammatory response which is characterized by production of a variety of hepatic proteins termed acute phase proteins. It has been shown that increased serum concentrations of several markers of the acute response, including IL-6, are elevated in patients with type 2 diabetes. These patients have a two-fold risk of PAD compared to those without type 2 diabetes. The G(-174)C IL-6 polymorphism has been suggested to influence IL-6 release, and its possible influence on PAD development among individuals with type 2 diabetes is discussed in this review. Further study of these molecules is justified as they appear to be involved in the development of PAD.     

Relationship of granulocyte colony stimulating factor with other acute phase reactants in man

The non-specific acute phase response in mice is associated with increased resistance to bacterial infection, which is critically mediated by granulocyte colony stimulating factor (G-CSF), but the behaviour of G-CSF in the human acute phase response is not known. Cardiothoracic surgery is a powerful acute phase stimulus and we show here that this procedure caused increased production of G-CSF, in addition to increases in the circulating concentrations of the proinflammatory cytokine interleukin (IL)-6 and the acute phase plasma proteins C-reactive protein (CRP) and serum amyloid A protein (SAA). Values of G-CSF correlated positively with IL-6 concentrations and circulating neutrophil counts, but not with CRP values. These results confirm that G-CSF is a physiological component of the acute phase response in humans that shares some of the same regulatory controls as IL-6, but its downstream effects are on neutrophils, not hepatic acute phase protein synthesis. Our observations are compatible with a protective role against bacterial infection for G-CSF in the human acute phase response, and support investigation of the prophylactic use of G-CSF in at-risk patients.     

Acute Phase Protein, Serum Amyloid A, Inhibits IL-1- and TNF-Induced Fever and Hypothalamic PGE2 in Mice

The effect of serum amyloid A (SAA) on fever induced by recombinant interleukin-1 beta (rIL-1 beta) or recombinant tumour necrosis factor alpha (rTNF alpha) was studied in mice. Serum amyloid A is an acute phase protein whose rise in pathological events is induced by the cytokines IL-1, IL-6 and TNF. Administration of human serum amyloid A to mice inhibited fever induced by rIL-1 beta or rTNF alpha in vivo, while the addition of human serum amyloid A to mice hypothalamic slices inhibited IL-1 beta- or TNF alpha-induced prostaglandin E2 (PGE2) production in vitro. Since serum amyloid A did not affect body temperature or hypothalamic PGE2 levels when administered alone, it may represent a specific servo-mechanism for fever regulation in acute events, and it suggests, for the first time, a possible feedback relationship between serum amyloid A and the immunoregulatory cytokines.     

Is amyloidogenesis during Alzheimer's disease due to an IL-1-/IL-6-mediated 'acute phase response' in the brain?

Alzheimer's disease is characterized by the presence of amyloid plaques in the brain, which comprise mainly beta-amyloid peptide and alpha 1-antichymotrypsin. Here, Peter Vandenabeele and Walter Fiers advance the hypothesis that this amyloidogenesis results from an IL-1-/IL-6-mediated acute phase reaction in the brain. They propose possible intracerebral sources of cytokines and acute phase proteins in microglia, astrocytes, neurons and cells of the choroid plexus.     

Interleukin-1 and interleukin-6 stimulate acute-phase protein production in primary mouse hepatocytes

Primary mouse hepatocytes were treated with the acute-phase mediators interleukin-1, interleukin-6, and glucocorticoids, singularly and in combination, in order to delineate the spectrum of proteins induced by the stimulatory factors. As found for rat and human liver cells, mouse hepatocytes responded to the cytokines by increasing production of acute-phase proteins, which in mice include haptoglobin, alpha 1-acid glycoprotein, complement C-3, serum amyloid A, and hemopexin. Serum amyloid A was unusual in that only the acidic peptide form responded to treatment with IL-1 and IL-6; the more basic form remained unchanged. In addition, an unidentified secretory protein was induced only by mixtures containing IL-6. The present study shows that a combination of IL-1, IL-6, and glucocorticoids is required for regulation of acute-phase plasma protein production in mouse liver cells.     

Hepatic over-expression of TGF-beta1 promotes LPS-induced inflammatory cytokine secretion by liver cells and endotoxemic shock

Transforming growth factor-beta (TGF-beta) is an important suppressor of inflammation. However, TGF-beta has also been found to promote secretion of inflammatory cytokines, and transgenic mice, which constitutively express TGF-beta in liver, have been found to be more susceptible to endotoxemia. To approach this apparent paradox, we investigated the role of hepatic TGF-beta1 in endotoxemia by utilising inducible TGF-beta1-transgenic mice that express TGF-beta1 under control of the C-reactive protein promoter. In contrast to non-transgenic littermates, administration of lipopolysaccharide (LPS) induced strongly increased expression of TGF-beta and acute phase proteins in the TGF-beta1-transgenic mice. Hepatic TGF-beta1-expression in the transgenic mice started an inflammatory cytokine cascade, marked by increased and prolonged secretion of TNF-alpha and IL-6 by hepatocytes. The inflammatory response of the TGF-beta1-transgenic mice to LPS was associated with high rates of mortality due to endotoxemic shock, marked by systemic hypotension and hypothermia. Endotoxemic shock was primarily mediated by TNF-alpha and IL-6, since inhibitory antibody to TNF-alpha or, more effectively, to IL-6 could reduce mortality in these mice. In conclusion, while TGF-beta-signalling to immune cells may suppress inflammatory effector function, TGF-beta-signalling to liver cells seems to promote LPS-stimulated secretion of inflammatory cytokines and to predispose for lethal endotoxemic shock.     

Blood Serum Levels of IL-2, IL-6, IL-8, TNF-α and IL-1β in Patients on Maintenance Hemodialysis

Cytokines are essential mediators of immune response and inflammatory reactions. Patients with chronic renal failure (CRF) commonly present with abnormalities of immune function related with impaired kidney function and the accumulation of uremic toxins in addition to bioincompatibility of dialyzer membranes. During a hemodialysis (HD) session, cytokines are released mainly by monocytes activated by endotoxin-type compounds in dialyzer fluid, complement factors and direct contact with dialyzer membrane. The study included 15 CRF patients, aged 36.4±2.9 years, on regular HD maintenance therapy for mean 68±10 months and 15 healthy controls. It was designed to assess serum levels of a panel of inflammatory cytokines: IL-1β, IL-2, IL-6, IL-8 and TNF-αin CRF patients on regular maintenance HD before, 20, 60 and 240 minutes of a single HD session in parallel with C-reactive protein (CRP) as an additional parameter. CRP concentration was increased in HD patients when compared with healthy controls. The concentrations of IL-1, IL-6, IL-8 and TNF-αwere increased, whereas the serum level of IL-2 was not altered during a single HD session.     

Changes in the acute phase complement component and IL-6 levels in patients with chronic hepatitis C receiving interferon alpha-2b

In order to study the effect of interferon alpha on the levels of acute phase complement proteins in vivo, serum concentrations of C9 and C1-inhibitor (C1-INH) were measured in patients with chronic hepatitis C before and 3 months after the beginning of interferon alpha2b therapy. Serum levels of the activation product of terminal complement pathway, C5b-9, HCV RNA and IL-6 were also determined. IFN alpha treatment significantly (P<0.0001) increased the serum concentrations of both complement proteins. C5b-9 levels were found to significantly decrease during the same period of time. When the patients were divided into responders or non-responders (more or less than 50% decrease in plasma HCV RNA concentrations) C9 and C1-INH levels were elevated only in the responder patients. There was no correlation between the changes of IL-6 levels or the amounts of IFN alpha administrated on one hand, and the changes in the complement protein levels on the other. These findings suggest that the marked increase in the serum concentrations of the acute phase complement proteins is a secondary phenomenon due to the IFN alpha-caused diminution of the viral load and the resulting immune complex-induced complement activation.     

The involvement of TNF, IL-1 and IL-6 in the immune response to protozoan parasites.

One early reaction of the host to infection with protozoan parasites is the secretion of an array of potent cytokines including tumor necrosis factor (TNF), interleukin (IL-1) and IL-6. The combined action of these cytokines causes fever, leukocytosis and the production of acute phase proteins such as C-reactive protein (CRP). These early responses contribute significantly to the outcome of infection by influencing the course of infection directly and by regulating the specific immune response to the parasite.     

Development of interleukin 6 and tumor necrosis factor alpha activity in nasopharyngeal secretions of infants and children during infection with respiratory syncytial virus.

Cytokine (interleukin 6 [IL-6] and tumor necrosis factor alpha [TNF-alpha]) activity in nasopharyngeal secretions of 21 infants and children (19 days to 16 months old) infected with primary respiratory syncytial virus was determined by an enzyme-linked immunosorbent assay. IL-6 and TNF-alpha were detectable in 100% (21 of 21) and 67% (14 of 21) of cases during the course of infection, respectively. Generally, TNF-alpha activity was high in the acute phase and declined thereafter, sometimes to undetectable levels. IL-6 activity was also highest in the acute phase and declined thereafter in infants younger than 5 months, while in patients older than 5 months, it-increased during the course of the disease to peak in the early convalescent phase. These observations suggest that inflammatory cytokines are produced in vivo in infants and children in response to primary respiratory syncytial virus infection and may be involved in disease pathogenesis. However, the mechanism of induction of cytokines may be different for infants and children in different age groups.     

Thalidomide suppressed IL-1beta while enhancing TNF-alpha and IL-10, when cells in whole blood were stimulated with lipopolysaccharide

Thalidomide is used to treat erythema nodosum leprosum (ENL). The events that precipitate this inflammatory reaction, which may occur in multibacillary leprosy patients, and the mechanism by which thalidomide arrest ENL, are not known. Thalidomide's ability to inhibit tumor necrosis factor alpha (TNF-alpha) in vitro has been proposed as a partial explanation of its effective treatment of ENL. In in vitro assays, thalidomide can enhance or suppress TNF-alpha. This is dependent on the stimulant used to evoke TNF-alpha; the procedure used to isolate the mononuclear cells from blood, and the predominant mononuclear cell type in the culture. To avoid artifacts that may occur during isolation of mononuclear cells from blood, we stimulated normal human blood with LPS and evaluated the effect of thalidomide and dexamethasone on TNF-alpha, and other inflammatory cytokines and biomarkers. Thalidomide suppressed interleukin 1 beta (IL-1beta) (p = 0.007), and it enhanced TNF-alpha (p = 0.007) and interleukin 10 (IL-10) (p = 0.031). Dexamethasone enhanced IL-10 (p = 0.013) and suppressed IL-1beta, TNF-alpha, interleukin 6 (IL-6), and interleukin 8 (IL-8) (p = 0.013). The two drugs did not suppress: C-reactive protein (CRP), Ig-superfamily cell-adhesion molecule 1 (ICAM 1), tumor necrosis factor receptor 1 (TNFR1), tumor necrosis factor receptor 2 (TNFR2), or amyloid A. In vitro and in vivo evidence is accumulating that TNF-alpha is not the primary cytokine targeted by thalidomide in ENL and other inflammatory conditions.     

Effect of interleukin-2 on peripheral blood mononuclear cell cytokine production and the hepatic acute phase protein response

This study investigated the ability of recombinant interleukin-2 (IL-2) to modulate the ability of peripheral blood mononuclear cells (PBMCs) to stimulate an acute phase protein response in isolated human hepatocytes. The effect of IL-2 on the production of tumour necrosis factor-alpha (TNF) and interleukin-6 (IL-6) by PBMCs isolated from patients with gastrointestinal cancer, multiple organ failure, and healthy controls was also studied. The ability of supernatants from IL-2-treated PBMCs to elicit an acute phase response in hepatocytes was then investigated. IL-2 had no effect on IL-6 or TNF production by PBMCs isolated from any group in the presence or absence of bacterial lipopolysaccharide (LPS). Despite this, preincubation of PBMCs with IL-2 significantly reduced the potential of LPS-stimulated PBMC supernatants to stimulate production of alpha1 antichymotrypsin, alpha1-acid glycoprotein, and C-reactive protein by hepatocytes. These observations were not due to a direct effect of IL-2 on hepatocyte acute phase protein production. These findings suggest that in this model IL-2 may modulate PBMC-induced acute phase protein production through an IL-6 and TNF-independent pathway.     

IL—4对治疗前后亚急性重型病毒性肝炎患者PBMCs TN …

OBJECTIVE: The aim of this study was to compare the influence of IL-4 on the expression of TNF-alpha and IL-1 alpha mRNA by PBMCs from patients with subfulminant viral hepatitis(SFH) before and after IL-4 treatment. METHODS: The expression levels of TNF-alpha and IL-1 alpha mRNA by PBMCs were assessed by semiquantitative RT-PCR. RESULTS: IL-4 suppressed the expression of both TNF-alpha and IL-1 alpha mRNA by PBMCs from SFH patients before and after treatment dose-dependently. However, their dose-response curves showed significant differences. The inhibitory effect could be observed at a concentration of 100 U/ml and was near to maximum at 1,000 U/ml in acute phase, whereas the same suppressive action of IL-4 was reached at 100 U/ml in recovery phase. When PBMCs were cultured in the presence of IL-4 at a concentration of 100 U/ml, IL-4 down-regulated the production of both TNF-alpha and IL-1 alpha mRNA by acute phase PBMCs only to 18.18-21.98% of control cells(in absence of IL-4), while the inhibitory rates were all near to 50% in recovery phases. Moreover, it was also found that the suppressive effect of IL-4 on the expression of PBMCs TNF-alpha and IL-1 alpha mRNA in the patients with endotoxinemia and HBeAg was significantly decreased in acute phase. CONCLUSIONS: The inhibitory effect of IL-4 on the expression of PBMCs TNF-alpha and IL-1 alpha mRNA is markedly decreased in acute phase as compared with that in recovery phase and this declined response may be related to endotoxinemia and viremia.     

Serum Cytokines in Patients with Legionella Pneumonia: Relative Predominance of Th1-Type Cytokines

Serum samples from 14 patients with Legionella pneumonia were examined for the presence of cytokines. In spite of high levels of serum C-reactive protein in all patients during the acute phase in only four cases (one involving interleukin-1β [IL-1β], three involving IL-6, and none involving tumor necrosis factor alpha) was the concentration of cytokines more than 100 pg/ml. Th2 cytokines IL-4 and IL-10 were detected in only one patient each. In contrast, significant increases of serum gamma interferon (IFN-γ) and IL-12 levels were observed during the acute phase in 6 and 11 cases, respectively. Interestingly, although serum IFN-γ levels diminished thereafter, in seven cases IL-12 levels remained high or increased further during the convalescent phase. In an additional 22 cases clinically suspected to be but not diagnosed as Legionella pneumonia, increases of serum IL-12 levels were observed in 16 cases, whereas the remaining 6 cases showed no detectable IL-12. Our results demonstrate the relative predominance of Th1 cytokine production in Legionella pneumonia. Although the role and significance of prolonged increases in IL-12 levels in Legionella disease are unknown, our results should prompt further investigation of the host immune response in terms of Th1 and Th2 balance in legionellosis.