Biosynthesis of human C-reactive protein in cultured hepatoma cells is induced by a monocyte factor(s) other than interleukin-1

Predicting abnormal C-reactive protein level for improving utilization by deep neural network model

BACKGROUND

C-reactive protein (CRP) is an inflammatory biomarker frequently used in clinical practice. However, insufficient evidence-based ordering inevitably results in its overuse or underuse. This study aims to predict its normal and abnormal levels using the deep neural network (DNN) models, helping clinicians order this item more appropriately and intelligently.

METHODS

We considered complete blood count (CBC) parameters as feature vectors and 10 mg/L as a cutoff value for CRP. Several models, including linear support vector classification, logistic regression, decision trees, random forests, and DNN, were developed based on a dataset of 53834 medical records to predict binary output. We externally validated DNN models on independent 20723 samples through discrimination, calibration curve, and decision curve analysis.

RESULTS

DNN models has the best area under the receiver operating characteristic curves (AUC). Learning curves revealed that models' AUC, balanced accuracy, and F1 score do not significantly and continuously improve following increasing data volume. In internal validation, the AUC, balanced accuracy, and the F1 score of 10 models were 0.818 (0.95 CI: 0.812-0.824), 0.741 (0.95 CI: 0.736-0.747), and 0.649 (0.95 CI: 0.643-0.656), respectively. These metrics were 0.817 (0.95 CI: 0.816-0.817), 0.741 (0.95 CI: 0.740-0.742), and 0.641 (0.95 CI: 0.640-0.642), respectively, in external validation. AUC and balanced accuracy shown no significant difference (P-values were 0.106 and 0.339). CRP10-C2 model has the lowest Brier score of 0.154, AUC of 0.818, and calibration curve formula of y=1.001x-0.010, which was identified as a target model to deploy in the app.

CONCLUSIONS

DNN models obtained moderate performance, surpassing baseline indices in distinguishing binary CRP levels. They are good generalizations and well-calibrated. The CRP-C2 model can enhance CRP utilization by informing the orders appropriately and can contribute to inflammatory diagnostics in primary health care where CBC is available, but the CRP test is inaccessible.

An Easy and Useful Noninvasive Score Based on α-1-acid Glycoprotein and C-Reactive Protein for Diagnosis of Patients with Hepatocellular Carcinoma Associated with Hepatitis C Virus Infection

This study aimed to evaluate the diagnostic value of α-1-acid glycoprotein (AGP) and C-reactive protein (CRP) and develop a predictive score to improve the diagnosis of hepatocellular carcinoma (HCC). AGP and CRP were measured in serum of 53 HCC patients and 20 liver cirrhosis (LC) patients, in addition to 15 healthy individuals. Area under receiver-operating characteristic curves (AUCs) was used to create a predictive score comprising AGP, CRP, alpha fetoprotein, and albumin. The diagnostic performances of score was determined and compared with AFP alone for the diagnosis of HCC. The combination of AGP, albumin, CRP, and AFP had AUC 0.92 and sensitivity 85% which was higher than AFP alone. The odds ratio of having HCC was 8.4 for AGP, 5.8 for CRP, 12.5 for AFP and 6.5 for albumin. Our score predicted HCC with an OR of 50.6 for HCC. The AUC of score in HCC with single tumor, absent vascular invasion and CLIP score (0-1) were 0.9, 0.9, 0.82, respectively, compared with 0.71, 0.71, 0.68, respectively, for AFP. In conclusion, a non-invasive and simple score based on AGP, CRP, AFP, and albumin could improve the accuracy of HCC diagnosis.

Prognostic value of C-reactive protein and neutrophil-to-lymphocyte ratio in patients with hepatocellular carcinoma

BACKGROUND

Accumulating evidence indicates that components of the systemic inflammatory response, such as C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR), have been associated with prognosis of various cancers. We aimed to elucidate whether CRP and NLR could serve as potential surrogate markers for response and survival in patients with hepatocellular carcinoma (HCC).

METHODS

The study population consisted of 318 consecutive patients with HCC. CRP and NLR were measured at baseline with follow-up measurements.

RESULTS

With the mean follow-up of 13.9 months, the median survival time was 13.8 months. Child-Pugh class, tumor size > 5 cm, tumor multiplicity, presence of portal vein thrombosis, α-fetoprotein > 200 ng/mL, CRP > 6.3 mg/L and NLR > 2.3 were identified as independent factors for worse survival of HCC (all p < 0.05). Patients with elevated CRP (> 6.3 mg/L) and elevated NLR (> 2.3) had a significantly shorter overall survival than those with low CRP and low NLR (all p < 0.001). The combined use of CRP and NLR provided incremental prognostic information. With significant inter-correlations, levels of CRP and NLR escalated with aggravating Child-Pugh class from A to C or progressing tumor stage from I to IV. CRP and NLR on baseline and serial measurements were well predictive of treatment response (p < 0.001).

CONCLUSIONS

CRP and NLR are independent indicators for survival in HCC patients, reflecting tumor burden and hepatic reserve. Their role in predicting tumor response and survival is more enhanced when used in combination. This study suggests that CRP and NLR are important prognostic biomarkers for HCC.

Interleukin-8 producing hepatocellular carcinoma with pyrexia

We discuss a patient who had poorly differentiated HCC with pyrexia and high CRP in laboratory data, which are not commonly observed in the usual HCC. A 50-year-old man with a history of liver dysfunction was admitted with a chief complaint of a prolonged fever and general fatigue. Preoperative diagnosis was HCC with portal vein tumor thrombus. Posterior segmentectomy of the liver and thrombectomy was performed. Rapid tumor recurrence occurred after surgery, and he died 79 days after the operation. Immunohistochemical stain of HCC in this patient revealed the production of proinflammatory cytokine, interleukin-8 (IL-8). IL-8 production may have contributed to the high fever, high inflammatory reaction, and poor prognosis in this case.

The impact of preoperative serum C-reactive protein on the prognosis of patients with hepatocellular carcinoma

BACKGROUND

The authors evaluated the significance of the preoperative serum C-reactive protein (CRP) level as a prognostic indicator in patients with hepatocellular carcinoma (HCC).

METHODS

One hundred forty-one patients who underwent curative resection for HCC were reviewed retrospectively. Clinicopathologic variables were compared between patients with serum CRP levels >/= 1.0 mg/dL (n = 22 patients; the CRP-positive group) and patients with serum CRP levels < 1.0 mg/dL (n = 119 patients; the CRP-negative group). Univariate and multivariate analyses were conducted to identify factors that affected survival and disease recurrence.

RESULTS

There was a significant correlation between the preoperative serum CRP level and tumor size. Invasion to the portal vein in the CRP-positive group was significantly more frequent than that in the CRP-negative group. Even after they underwent curative resection, 75.3% of patients in the CRP-positive group experienced recurrence within 1 year. The overall survival and recurrence-free survival rates in the CRP-positive group were significantly lower compared with the rates in the CRP-negative group. On multivariate analysis, the preoperative serum CRP level was selected as one of the unfavorable indicators regarding survival and recurrence. When CRP levels, albumin levels, and platelet counts that were available before surgery were scored as a combined index, the total score demonstrated a good stratification value for survival after hepatic resection.

CONCLUSIONS

The current results showed that the preoperative serum CRP level is an independent and significant indicator predictive of poor prognosis and early recurrence in patients with HCC. The new CRP-based scoring system offers reliable information for predicting survival.

The link of biocompatibility to cytokine production

Recent studies suggest that chronic inflammation plays a role in the pathogenesis of cardiovascular disease. Cytokines released from jeopardized tissues stimulate the liver to synthesize acute phase proteins, including C-reactive protein (CRP). Baseline levels of CRP in apparently healthy persons or in persons with unstable angina constitute an independent risk factor for cardiovascular events. More recently, it has been suggested that CRP is useful not only as a marker of the acute phase response, but is also involved in the pathogenesis of the disease. CRP may, in fact, directly interact with the atherosclerotic vessels or ischemic myocardium by activation of the complement system, thereby promoting inflammation and thrombosis. Several studies in uremic patients have implicated CRP as a marker of malnutrition, resistance to erythropoietin, and chronic stimulation in hemodialysis. An increased cytokine production secondary to blood interaction with bioincompatible dialysis components has been reported by several studies; interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and mainly IL-6 are the three proinflammatory cytokines involved in the pathogenesis of hemodialysis-related disease. We have provided evidence for the occurrence of high CRP and IL-6 levels in chronic dialytic patients exposed to contaminate dialysate and suggest that backfiltration may induce a chronic, slowly developing inflammatory state that may be abrogated by avoiding backfiltration of contaminate dialysate. Therefore, CRP is implicated as a marker linking bioincompatibility associated with backfiltration and increased cytokine production with a clinical state of chronic inflammation.

Role of serum C-reactive protein as a marker of hepatocellular carcinoma in patients with cirrhosis

BACKGROUND

The usefulness of C-reactive protein (CRP) as a tumour marker in patients with hepatocellular carcinoma (HCC) is controversial. The purpose of this study was to determine whether CRP estimation could be used to identify patients with HCC among those with cirrhosis.

METHODS

Serum levels of CRP and alpha-fetoprotein (AFP) were investigated in 122 previously untreated patients with cirrhosis and HCC. Another 76 patients with cirrhosis alone were also investigated as controls.

RESULTS

Of the subjects tested, 47.5% of patients with HCC and 39.5% of controls had elevated CRP values (> 6 microg/mL). Although using elevated CRP and/or AFP (> 20 ng/mL) as a criterion showed a significant difference between controls and patients with multiple nodular, massive, or diffuse type HCC (all P < 0.005), the clinical application of this criterion was limited because of low specificity (58%) and accuracy (all < 73%). By using receiver-operating characteristic curves no valuable threshold value of CRP was found to discriminate various types of HCC, except for distinguishing the diffuse type from controls. The CRP value of 12 microg/mL could be used as the cut-off value to differentiate diffuse-type HCC from controls (sensitivity 82.4%, specificity 82%, accuracy 82.1%, P<0.005).

CONCLUSIONS

Serum CRP is not a good marker for HCC. However, very high values of CRP in patients with cirrhosis may suggest the presence of a diffuse-type HCC.

Acute phase proteins and transformed cells

Acute phase proteins (APP) are plasma proteins whose concentration and glycosylation alters in response to tissue injury, inflammation, or tumor growth. Significant interspecies and sex differences in APP response exist. APP are produced mainly by hepatocytes, and their synthesis and glycosylation are controlled by a network consisting of cytokines, their soluble receptors, and glucocorticoids. The major cytokines involved in these processes belong to a group of interleukin-6-type cytokines that act through the hematopoietin receptor complex on hepatocytes and JAK-STAT signal transduction pathway. Transformed cells (hepatoma) display significant differences in synthesis of APP, cytokine responsiveness, expression of cytokine-receptor subunits and signal-transduction machinery. The most striking variability relates to the glycosylation alterations induced by cytokines. However, transformed cells (hepatoma) form a basic model for studying and understanding mechanisms controlling the synthesis and glycosylation of APP. Furthermore, APP may be secreted by transformed (tumor) cells of various origins and may display a growth factor-like function in certain cancer types.

Comparative study of C-reactive protein in chronic hepatitis B and chronic hepatitis C

C-reactive protein (CRP) is a liver-specific acute-phase protein, and its expression in hepatocyte is regulated by cytokines such as interleukin-1, interleukin-6 and tumor necrosis factor-alpha. Although several alterations in cytokines have been found in patients with chronic viral hepatitis, it remains obscure how CRP expression is associated with progression of the disease in chronic viral infection. In the present study, CRP expression was evaluated in 45 patients with chronic hepatitis B and in 38 patients with chronic hepatitis C. By the immunohistochemical analysis, the intensity of CRP expression in hepatocyte was closely associated with the histology activity index (HAI) score in chronic hepatitis B. In contrast, the association was not found in chronic hepatitis C. When serial changes in serum levels of CRP were compared in long-term follow-up patients including 5 patients with chronic hepatitis B and 4 patients with chronic hepatitis C, serum levels of CRP fluctuated simultaneously with serum levels of alanine aminotransferase in chronic hepatitis B, whereas the correlation was not recognized in chronic hepatitis C. These results suggest that CRP expression correlates with progression of the disease in chronic hepatitis B, but not in chronic hepatitis C. It is also possible that cytokine-mediated response is more pronounced in chronic hepatitis B than in chronic hepatitis C.

The major acute phase reactants: C-reactive protein, serum amyloid P component and serum amyloid A protein

Following an acute phase stimulus, such as infection or physical injury, many liver-derived plasma proteins are increased in concentration. These provide enhanced protection against invading micro-organisms, limit tissue damage and promote a rapid return to homeostasis. Diana Steel and Alexander Whitehead discuss the gene structure, regulation and possible clinical significance of the most dramatically induced acute phase reactants.

Disturbances in acute phase plasma proteins during melancholia: additional evidence for the presence of an inflammatory process during that illness

1. Leukocyte enumeration through flow cytometry has revealed that severe depression may be accompanied by a systemic immune activation, indicative of an inflammatory response. The latter condition allegedly involves an important modification of acute phase plasma protein (APP) equilibrium. 2. In order to elucidate whether the state of severe depression is represented by alterations in APPs, the authors measured: alpha 1 antitrypsin (alpha 1 AT), alpha 2 macroglobulin (alpha 2 M), haptoglobin (Hp), alpha 1 acid glycoprotein (alpha 1 S), transferrin (Tf), complement component 4 (C4) and C-reactive protein (CRP). Interleukin-1-beta (II-1 beta) and interleukin-6 (II-6) circulating levels were determined. 3. Hyperhaptoglobinemia and hypotransferrinemia are hallmarks for major depression and depression per se, respectively. The disorders in Hp and Tf circulating levels are highly sensitive to (83%) and specific for (100%) melancholia as opposed to the healthy state. 4. Disorders in both APPs are significantly related to the absolute number of blood monocytes. 5. The authors observed a trend towards lower alpha 2M and higher alpha 1S values in severely depressed subjects. Severity of depression was significantly related to Hp and alpha 1S (both positively) and to alpha 2M and Tf (both negatively) values. 6. No significant intercategory differences in C4 could be established, whilst only a few subjects exhibited measurable CRP, II-1 beta and II-6 circulating levels. 7. Our findings may support the hypothesis that depression is accompanied by an inflammatory response.

Peripheral blood monocyte cytokine production and acute phase response in inflammatory bowel disease

Cytokines released from activated mononuclear leukocytes are involved in triggering the acute phase response and many of the inflammatory manifestations of ulcerative colitis and Crohn's disease. The ability of circulating monocytes from patients with ulcerative colitis and Crohn's disease to generate the cytokines interleukin 1 beta (IL 1 beta) and tumour necrosis factor alpha (TNF alpha), both spontaneously and in response to stimulation by lipopolysaccharide, was compared. IL 1 beta generation in response to lipopolysaccharide was significantly higher in Crohn's disease than in ulcerative colitis and normal controls, with a dramatic increase in patients with active disease. There was a significant reduction in lipopolysaccharide stimulated TNF alpha generation in ulcerative colitis patients compared with Crohn's disease and normal control subjects. IL 1 beta and TNF alpha release correlated significantly with serum C reactive protein and serum alpha 1 acid glycoprotein in Crohn's disease. The ability of conditioned medium from monocytes in Crohn's disease to enhance release of alpha 1 acid glycoprotein from the liver cell line HepG2 in culture was assessed. There was a significant positive correlation between TNF alpha and IL 1 beta presence in the supernatant and alpha 1 acid glycoprotein production. The differences in the cytokine profile in patients with Crohn's disease compared with ulcerative colitis suggest an intrinsic difference in the ability to produce cytokines in patients with these two forms of inflammatory bowel disease, and may explain features such as the enhanced ability to generate a brisk C reactive protein response in Crohn's disease.

Cloning and structural characterization of a rabbit genomic DNA for alpha 1 acid glycoprotein

The gene for rabbit alpha 1 acid glycoprotein (AGP) has been isolated from a lambda EMBL3 genomic DNA library. Isolated clone contains a 12 Kbp fragment of rabbit genomic DNA. Restriction endonuclease mapping has localized the gene within a 4.2 Kbp fragment spanning two EcoRI sites. Southern blot analysis of the rabbit genomic DNA and its comparison with the cloned gene indicates that there is only one gene for AGP present per genome. DNA sequence analysis of the cloned gene indicates that the entire gene, TATA box to the polyadenylation signal, is located within the 4.2 Kbp region and contains six exons representing the full-length cDNA described earlier (1). The 5'-end of alpha 1-AGP gene sequences from rabbit, human, rat and mouse have been compared. Such analysis reveals two conserved regions located between -63 bp and -36 bp and -29 bp and -1 bp of putative transcription start site, which may play a role in transcriptional induction of this gene during acute response. In addition to this conserved domain, DNA sequence upstream of the major transcription start site contains a potential element for Sp1 binding and a 18 bp long palindrome sequence followed by a short repeating dinucleotide sequence, which may be important in the regulation of AGP gene induction.

Stimulation of CRP secretion in HepG2 cells: cooperative effect of dexamethasone and interleukin 6

This report described the capability of the human. human acute phase reactant, C-reactive protein (CRP). Its secretion is stimulated by interleukin 6 (IL-6) in a dose-dependent fashion and can further be positively modulated by dexamethasone. The way in which this glucocorticoid influences the CRP response depends on its time of application. Incubation of HepG2 cells simultaneously with IL-6 and dexamethasone increases the magnitude of CRP release significantly above that seen with IL-6 alone. After preincubation with dexamethasone, the kinetics of CRP release, induced by IL-6, are increased and approach that observed in the case of alpha 1-acid glycoprotein (alpha 1-AGP) without dexamethasone pretreatment. Conditions for optimal secretion of CRP were determined.

Effect of alpha-2-macroglobulin on cytokine-mediated human C-reactive protein production

Alpha-2-macroglobulin (alpha 2-M), a serum protease inhibitor that also binds cytokines, neutralized the inhibitory effect exerted by transforming growth factor-beta (TGF-beta) on IL-6-induced C-reactive protein (CRP) production by the human hepatoma cell line PLC/PRF/5. alpha 2-M was found to bind noncovalently with TGF-beta to form a complex that, upon acidification, released TGF-beta inhibitory activity as detected by IL-6-induced CRP production. Although alpha 2-M also binds IL-6, it did not alter IL-6-induced CRP production by the hepatoma cells. The interaction between alpha 2-M and TGF-beta may influence the production of acute-phase proteins by liver hepatocytes.

Acute-phase response of human hepatocytes: regulation of acute-phase protein synthesis by interleukin-6

Human hepatocytes in primary culture were used as a model system to investigate the mechanism(s) involved in the induction of the acute-phase response in human liver. Hepatocytes were incubated with increasing amounts of recombinant human interleukin-1 beta, recombinant interleukin-6 and tumor necrosis factor-alpha. Synthesis of C-reactive protein was studied at the mRNA and protein levels. Only recombinant interleukin-6 was capable of inducing C-reactive protein-mRNA and C-reactive protein-protein synthesis. Also, fibrinogen and alpha-1-antitrypsin synthesis measured by immunoprecipitation with specific antisera increased in a dose-dependent, time-dependent manner, whereas albumin synthesis decreased to about 50% of controls. Maximal effects were observed at 100 to 300 units of recombinant interleukin-6/ml culture medium after 20 hr of incubation. Although the synthetic glucocorticoid dexamethasone slightly modulated the effect of recombinant interleukin-6, it was not an absolute requirement for the induction of acute-phase protein synthesis in human hepatocytes. In pulse-chase experiments it was shown that the time course of the disappearance of the acute-phase proteins from the cells and their appearance in the medium is not influenced by recombinant interleukin-6. This finding suggests that recombinant interleukin-6 exerts its regulatory effect on acute-phase protein synthesis at the pretranslational level.

IL-1 and IL-6 mediate increased production and synthesis by hepatocytes of acute-phase reactant mouse serum amyloid P-component (SAP)

Primary mouse hepatocytes exposed to the inflammatory cytokines IL-1 and IL-6 in vitro displayed an increase in the production of the major acute-phase reactant, serum amyloid P-component (SAP). Antiserum to recombinant human IL-6 selectively neutralized the SAP-inducing activity secreted by human diploid fibroblasts. Purified mouse interferon-beta (IFN-beta), but not IFN-alpha, also induced SAP production. Addition of 0.05 ng/ml of recombinant mouse IL-1 alpha induced a 10-fold increase in SAP production, whereas recombinant human and recombinant mouse IL-6 displayed optimal SAP-inducing activity of four-fold and seven-fold at 10 ng/ml and 1 unit/ml/2 x 10(5) mouse hepatocytes, respectively. The SAP-inducing activity was neutralized by antibodies to each of the recombinant cytokines. The kinetics of the SAP response in vitro was similar for all of the cytokines. Addition of a mixture of IL-1 and IL-6 to the hepatocytes resulted in SAP production that was not synergistic, but additive, over a range of concentrations for each cytokine. The increase in SAP production mediated by the cytokines was in part the result of an increase in the level of SAP mRNA. Metabolic incorporation of [35S]methionine into mouse SAP occurred in response to both IL-1 and IL-6. Therefore, mouse SAP should be classified among the subset of acute-phase proteins that can be induced by the direct action of either IL-1 or IL-6 on hepatocytes.

Serum C-reactive protein as a serum marker for the diagnosis of hepatocellular carcinoma

An abnormal serum C-reactive protein (CRP) level (greater than 10 mg/l) was found in 78% of 104 patients with hepatocellular carcinoma (HCC), 8% of 12 asymptomatic hepatitis B surface antigen carriers, 5% of 77 patients with chronic hepatitis, and 9% of 55 cirrhotic patients without complications. It was also discovered in 72% of 25 cirrhotic patients complicated with bacterial infections, gastrointestinal bleeding, hepatic encephalopathy, or massive ascites, 67% of nine common bile duct stone patients, and 79% of 14 patients with malignancies other than HCC. A dramatic decrease in serum CRP levels was found in two HCC patients receiving a successful surgical tumor resection, four cirrhotic patients recovering from complications, and all six patients with common bile duct stones and cholangitis controlled by antibiotics, but not in untreated HCC or other malignancy patients. Serum alpha-fetoprotein (AFP) levels correlated poorly with CRP levels. A combination of these two serum markers identified 94% of 104 patients with HCC. Since serum CRP levels were also abnormal in 57% of 14 patients with resectable HCC (less than or equal to 5 cm), in conjunction with AFP, it may be useful in the diagnosis of HCC or other malignancies.

Further cellular investigation of the human hepatoblastoma-derived cell line HepG2: morphology and immunocytochemical studies of hepatic-secreted proteins

The hepatoblastoma cell line HepG2 has been a matter of many investigations; most of them include biochemical studies of lipoprotein and other hepatic protein metabolism. However, the accurate cellular features of these cells have not been emphasized. We studied the cellular histologic, histochemical, and ultrastructural characteristics of this cell line. In addition, we investigated by immunoenzymatic methods the cellular biosynthesis of several proteins: apolipoproteins-AI, -B, -D, and -E, albumin, alpha-fetoprotein, transferrin, alpha-1-antitrypsin, C-reactive protein, fibronectin, and collagens I, III and IV. The rates of accumulation, in the medium of HepG2 cells, of albumin, alpha-1-antitrypsin, transferrin, and alpha-fetoprotein were 13.2 +/- 1.9; 4.9 +/- 1.5; 3.2 +/- 0.4; and 10.7 +/- 1.7 micrograms/10(6) cells/24 h, respectively. Our results show that HepG2 cells exhibited most cellular features of normal human hepatocytes. Bile canaliculi as well as Golgi apparatus complexes were particularly developed. Except for the C-reactive protein, HepG2 cells have all retained the ability to synthesize hepatic proteins but with some variable intensity from cell to cell. This hepatoblastoma cell line seems to represent a useful tool in the understanding of hepatic protein biosynthesis, particularly for the investigation on the secretory pathway of plasma proteins.

Cell-free-synthesized interleukin-6 (BSF-2/IFN-beta 2) exhibits hepatocyte-stimulating activity

Secretory products of cultured human blood monocytes contain a hepatocyte-stimulating factor which is able to induce the acute-phase proteins alpha 2-macroglobulin and fibrinogen in rat liver cells. Total RNA was isolated from unstimulated and lipopolysaccharide-stimulated human monocytes and translated in a reticulocyte lysate. The capability of the cell-free synthesized proteins to induce the acute-phase proteins alpha 2-macroglobulin and fibrinogen was assayed in rat hepatocyte primary cultures and in the rat hepatoma cell line Fao. The products translated from the mRNA of lipopolysaccharide-stimulated human monocytes induced mRNAs for alpha 2-macroglobulin and fibrinogen and therefore contain hepatocyte-stimulating factor. The translation products of unstimulated monocytes had no effect. A cDNA containing the coding sequence for interleukin-6 (B-cell stimulatory factor 2, interferon-beta 2/26-kDa protein, interleukin HP1) derived from human T-cells cloned into the transcription vector pGEM4 was transcribed in vitro. Translation of the isolated RNA in a reticulocyte lysate led to the synthesis of a protein of about 25 kDa. This cell-free synthesized interleukin-6 exhibited hepatocyte-stimulating activity measured by the induction of beta-fibrinogen mRNA in Fao cells. Using an antibody against interleukin-6, two proteins of 22 kDa and 23 kDa were immunoprecipitated from the culture medium of lipopolysaccharide-stimulated human monocytes. These two proteins were not synthesized by unstimulated monocytes. When total RNA from unstimulated human monocytes and lipopolysaccharide-stimulated human monocytes and lymphocytes was subjected to Northern analysis and hybridized with the interleukin-6 cDNA, a strong hybridization signal corresponding to an RNA of about 1300 bases was detected only in the RNA from lipopolysaccharide-stimulated human monocytes, indicating that human monocytes express the interleukin-6 gene after stimulation. The data presented in this paper strongly suggest that hepatocyte-stimulating factor from human monocytes and interleukin-6 from T-cells are identical.

Effect of auranofin on plasma fibronectin, C reactive protein, and albumin levels in arthritic rats

Auranofin, a member of a class of compounds with disease modifying activity, was given to arthritic rats to determine if it could reverse the abnormal plasma concentrations of fibronectin (Fn), C reactive protein (CRP), and albumin, which were unaffected by treatment with non-steroidal anti-inflammatory drugs (NSAIDs). When auranofin was orally administered for two weeks to adjuvant induced arthritic rats it significantly inhibited swelling of the injected and non-injected paws at doses of 3 and 10 mg/kg. Rocket electroimmunoassay measurement of plasma proteins in normal, arthritic, and auranofin treated arthritic rats indicated that auranofin at 10 mg/kg significantly decreased (by 77%) the abnormally high concentration of arthritic rat plasma Fn, though it had no effect on Fn concentrations when administered to normal rats. CRP, which was raised approximately twofold above normal in arthritic rats, was reduced by 56% after treatment of arthritic rats with auranofin at 10 mg/kg, though CRP concentrations in normal rats were unaffected by auranofin treatment. Depressed albumin concentrations in arthritic rats were significantly enhanced (by 30%) by dosing with 10 mg/kg of auranofin. At the 3 mg/kg dose, auranofin did not significantly change plasma concentrations of Fn, CRP, and albumin in arthritic rats. At a dose of 10 mg/kg, however, auranofin, in addition to inhibiting chronic systemic paw inflammation, also altered abnormal concentrations of plasma Fn, CRP, and albumin in the adjuvant arthritic rat, thus distinguishing auranofin from standard NSAIDs we have previously tested.

Modulation of the acute phase response and in vitro measurement of interleukin-1 activity following administration of dexamethasone to adjuvant-arthritic rats

Adjuvant-arthritic (AA) rats were medicated with dexamethasone to determine if this glucocorticoid suppressed the activity of interleukin-1 (IL-1) or the acute phase response. Dexamethasone (0.1 mg/kg, p.o.) administered daily for two weeks to AA rats, significantly (p less than or equal to 0.01) decreased high splenic IL-1 production (60% inhibition). Dexamethasone at a 0.5 mg/kg dose reduced AA rat splenic IL-1 production below normal (100% inhibition). In addition, dexamethasone significantly inhibited the AA rat acute phase response as measured by reduction of plasma C-reactive protein levels and enhancement of plasma albumin and iron levels. Following medication with 0.02, 0.1 or 0.5 mg/kg dexamethasone, high plasma C-reactive protein levels decreased by 33, 77 and 95% respectively, compared to untreated AA controls. Under the same dosing regimen of 0.02, 0.1 or 0.5 mg/kg dexamethasone, plasma albumin levels increased by 44, 128 and 239% respectively, while plasma iron levels rose by 19, 64 and 98% respectively, compared to AA controls. At the 0.02, 0.1 and 0.5 mg/kg doses dexamethasone also significantly reduced injected and noninjected paw swelling in AA rats. In view of the ability of dexamethasone to decrease IL-1 production and the acute phase response often associated with it, it is possible that part of the anti-inflammatory activity of dexamethasone may stem from inhibition of IL-1 formation in vivo.

Regulation of synthesis and secretion of major rat acute-phase proteins by recombinant human interleukin-6 (BSF-2/IL-6) in hepatocyte primary cultures

The regulation of the three major acute-phase proteins alpha 2-macroglobulin, cysteine proteinase inhibitor and alpha 1-antitrypsin by recombinant human interleukin-1 beta, recombinant human interleukin-6 and recombinant human tumor necrosis factor alpha was studied in rat hepatocyte primary cultures. Synthesis and secretion of the acute-phase proteins was measured after labeling with [35S]methionine and immunoprecipitation. Incubation of hepatocytes with interleukin-6 led to dose-dependent and time-dependent changes in the synthesis of the three major acute-phase proteins and albumin, similar to those occurring in vivo during experimental inflammation. alpha 2-Macroglobulin and cysteine proteinase inhibitor synthesis was induced 54-fold and 8-fold, respectively, 24 h after the addition of 100 units/ml interleukin-6. At the same time synthesis of the negative acute-phase protein albumin was reduced to 30% of controls. Half-maximal effects were achieved with 4 units interleukin-6/ml. Interleukin-1 beta had only a partial effect on the regulation of the four patients studied: only a twofold stimulation of alpha 2-macroglobulin and a 60% reduction of albumin synthesis were observed. Tumor necrosis factor alpha did not alter the synthesis of acute-phase proteins. The stimulation of alpha 2-macroglobulin and cysteine proteinase inhibitor synthesis by interleukin-6 was inhibited by interleukin-1 beta in a dose-dependent manner. In pulse-chase experiments the effect of interleukin-1 beta, interleukin-6 and tumor necrosis factor alpha on the secretion of acute-phase proteins was examined. Interleukin-6 markedly accelerated the secretion of total proteins and alpha 2-macroglobulin, whereas the secretion of cysteine proteinase inhibitor, alpha 1-antitrypsin and albumin was not affected. The inhibition of N-glycosylation by tunicamycin abolished the effect of interleukin-6 on the secretion of alpha 2-macroglobulin, indicating a possible role of interleukin-6 on N-glycosylation.

Recombinant human B cell stimulatory factor 2 (BSF-2/IFN-beta 2) regulates beta-fibrinogen and albumin mRNA levels in Fao-9 cells

Conditioned medium from human monocytes contains a partially characterized hepatocyte-stimulating factor that simultaneously elevates the mRNA levels of the acute-phase protein beta-fibrinogen and decreases albumin mRNA in rat hepatoma cells. We demonstrate that recombinant human B-cell stimulatory factor 2, which is identical to interferon-beta 2/26 kDa protein and interleukin-HP1, exhibits the same activity as hepatocyte-stimulating factor. Furthermore, a specific antibody against B-cell stimulatory factor 2 was able to inhibit hepatocyte-stimulating factor in conditioned medium from human monocytes. Our data show that hepatocyte-stimulating factor and B-cell stimulatory factor 2 are functionally and immunologically related proteins.