Interleukin 6, the third mediator of acute-phase reaction, modulates hepatic protein synthesis in human and mouse. Comparison with interleukin 1 beta and tumor necrosis factor-alpha

Ceruloplasmin and cardiovascular disease

Transition metal ion-mediated oxidation is a commonly used model system for studies of the chemical, structural, and functional modifications of low-density lipoprotein (LDL). The physiological relevance of studies using free metal ions is unclear and has led to an exploration of free metal ion-independent mechanisms of oxidation. We and others have investigated the role of human ceruloplasmin (Cp) in oxidative processes because it the principal copper-containing protein in serum. There is an abundance of epidemiological data that suggests that serum Cp may be an important risk factor predicting myocardial infarction and cardiovascular disease. Biochemical studies have shown that Cp is a potent catalyst of LDL oxidation in vitro. The pro-oxidant activity of Cp requires an intact structure, and a single copper atom at the surface of the protein, near His(426), is required for LDL oxidation. Under conditions where inhibitory protein (such as albumin) is present, LDL oxidation by Cp is optimal in the presence of superoxide, which reduces the surface copper atom of Cp. Cultured vascular endothelial and smooth muscle cells also oxidize LDL in the presence of Cp. Superoxide release by these cells is a critical factor regulating the rate of oxidation. Cultured monocytic cells, when activated by zymosan, can oxidize LDL, but these cells are unique in their secretion of Cp. Inhibitor studies using Cp-specific antibodies and antisense oligonucleotides show that Cp is a major contributor to LDL oxidation by these cells. The role of Cp in lipoprotein oxidation and atherosclerotic lesion progression in vivo has not been directly assessed and is an important area for future studies.

Identification of genes differentially expressed in canine vasospastic cerebral arteries after subarachnoid hemorrhage

To understand the molecular processes of continuous vasospasm of cerebral arteries after subarachnoid hemorrhage, mRNA differential display and screening of cDNA expression array were performed to identify genes that are differentially expressed in vasospastic arteries of canine two-hemorrhage models. The expression levels of 18 genes were found to be upregulated, and those of two genes to be downregulated. Of these, 12 represent known genes or homologues of genes characterized previously, and the other eight genes are not related to any sequences in the databases. The known genes include five upregulated inflammation-related genes encoding monocyte chemotactic protein-1, cystatin B, inter-alpha-trypsin inhibitor family heavy chain-related protein, serum amyloid A protein, and glycoprotein 130, suggesting that inflammatory reaction may be involved in the development of cerebral vasospasm. The upregulation of three known genes encoding stress-related proteins of vascular endothelial growth factor, BiP protein, and growth-arrest and DNA-damage-inducible protein may be involved in possible cell survival in the damaged arteries. A full-length cDNA for the unknown clone DVS 27, whose expression was most highly upregulated, was isolated from the cerebral artery cDNA library by hybridization. Characterization of these genes should help to clarify the molecular mechanism of continuous cerebral vasospasm after subarachnoid hemorrhage.

Serum amyloid A, the major vertebrate acute-phase reactant

The serum amyloid A (SAA) family comprises a number of differentially expressed apolipoproteins, acute-phase SAAs (A-SAAs) and constitutive SAAs (C-SAAs). A-SAAs are major acute-phase reactants, the in vivo concentrations of which increase by as much as 1000-fold during inflammation. A-SAA mRNAs or proteins have been identified in all vertebrates investigated to date and are highly conserved. In contrast, C-SAAs are induced minimally, if at all, during the acute-phase response and have only been found in human and mouse. Although the liver is the primary site of synthesis of both A-SAA and C-SAA, extrahepatic production has been reported for most family members in most of the mammalian species studied. In vitro, the dramatic induction of A-SAA mRNA in response to pro-inflammatory stimuli is due largely to the synergistic effects of cytokine signaling pathways, principally those of the interleukin-1 and interleukin-6 type cytokines. This induction can be enhanced by glucocorticoids. Studies of the A-SAA promoters in several mammalian species have identified a range of transcription factors that are variously involved in defining both cytokine responsiveness and cell specificity. These include NF-kappaB, C/EBP, YY1, AP-2, SAF and Sp1. A-SAA is also post-transcriptionally regulated. Although the precise role of A-SAA in host defense during inflammation has not been defined, many potential clinically important functions have been proposed for individual SAA family members. These include involvement in lipid metabolism/transport, induction of extracellular-matrix-degrading enzymes, and chemotactic recruitment of inflammatory cells to sites of inflammation. A-SAA is potentially involved in the pathogenesis of several chronic inflammatory diseases: it is the precursor of the amyloid A protein deposited in amyloid A amyloidosis, and it has also been implicated in the pathogenesis of atheroscelerosis and rheumatoid arthritis.

Inducible Expression and Regulation of the α1-Acid Glycoprotein Gene by Alveolar Macrophages: Prostaglandin E2 and Cyclic AMP Act as New Positive Stimuli

We have reported that α1-acid glycoprotein (AGP) gene expression was induced in lung tissue and in alveolar type II cells during pulmonary inflammatory processes, suggesting that local production of this immunomodulatory protein might contribute to the modulation of inflammation within the alveolar space. Because AGP may also be secreted by other cell types in the alveolus, we have investigated the expression and the regulation of the AGP gene in human and rat alveolar macrophages. Spontaneous AGP secretion by alveolar macrophages was increased 4-fold in patients with interstitial lung involvement compared with that in controls. In the rat, immunoprecipitation of [35S]methionine-labeled cell lysates showed that alveolar macrophages synthesize and secrete AGP. IL-1β had no effect by itself, but potentiated the dexamethasone-induced increase in AGP production. RNase protection assay demonstrated that AGP mRNA, undetectable in unstimulated cells, was induced by dexamethasone. Conditioned medium from LPS-stimulated macrophages as well as IL-1β had no effect by themselves, but potentiated the dexamethasone-induced increase in AGP mRNA levels. In addition to cytokines, PGE2 as well as dibutyryl cAMP increased AGP mRNA levels in the presence of dexamethasone. When AGP expression in other cells of the monocyte/macrophage lineage was examined, weak and no AGP production by human blood monocytes and by rat peritoneal macrophages, respectively, were observed. Our data showed that 1) AGP expression is inducible specifically in alveolar macrophages in vivo and in vitro; and 2) PGE2 and cAMP act as new positive stimuli for AGP gene expression.

Coordinated regulation of ceruloplasmin and metallothionein mRNA by interleukin-1 and copper in HepG2 cells

During the acute phase response, cytokines induce hepatic metallothionein and ceruloplasmin synthesis and the uptake of metals. We have investigated how copper and cytokines may interact in controlling ceruloplasmin (CP) and metallothionein mRNA in liver cells. We found that IL-1alpha, IL-1beta and IL-6 increased both metallothionein-1 (MT-1) and metallothionein-2 (MT-2) mRNA in HepG2 cells. The time and pattern of induction was different, both IL-1alpha and IL-1beta inducing two peaks of MT-1 and MT-2, with that of MT-2 being much larger. IL-6 induced only low levels of both MT-1 and MT-2 mRNA. CP mRNA was also increased after 16 h by IL-1beta, whereas IL-1alpha induced two CP peaks at 8 and 20 h, while IL-6 had little effect. Copper administration gave rise to substantially increased MT-1 mRNA, a slightly lower increase in MT-2 and also a significant increase in CP mRNA with similar kinetics. These parallel increases in MT and CP mRNA suggest that the coordinated expression of these proteins may be important for their synthesis during the acute phase response.

Serum cytokines in chronic Chagas' disease

We studied the serum levels of IL-2, IFN-gamma and TNF in different clinical forms of Chagas' disease and in patients clinically compensated and decompensated. Cytokines measured in 91 patients with the chronic form of the disease did not differ from those of 13 normal individuals, suggesting the absence of activation of the TH1 pattern of lymphocyte response. There were no statistical differences among the 17 patients in the indeterminate form of the disease, the patients presenting either early (n = 4) or well-developed signs of cardiomyopathy (n = 62), the digestive (n = 4) or the mixed (n = 4) forms of the disease. Serum TNF was undetectable and IFN-gamma levels did not differ between clinical forms and severities of Chagas' disease. However, we found IL-2 higher levels in the 25 non-controlled patients than in the 66 controlled individuals (p < 0.001). We suggest that IL-2 dosage may be useful as an indicator of the need for more aggressive procedures.

In vitro C3 mRNA expression in Pemphigus vulgaris: complement activation is increased by IL-1alpha and TNF-alpha

BACKGROUND

Pemphigus vulgaris (PV) is a potentially life-threatening disease, characterized immunohistologically by IgG deposits and complement activation on the surface of keratinocytes. Complement activation has been implicated in the pathogenesis with C3 deposits in about 90% of patients.

OBJECTIVE

In order to further elucidate the role of complement in PV and to define which cytokines play a role in C3 mRNA expression, we performed an in vitro study in human keratinocytes.

METHODS

Normal human epidermal keratinocytes (NHuK) were incubated with PV serum and C3 mRNA was measured. We previously had shown that IL-1alpha and TNF-alpha are expressed in PV in vivo and in vitro. Since cytokines are able to modulate complement activation, mRNA expression was evaluated in a similar experiment after pretreatment using antibodies against IL-1alpha and TNF-alpha.

RESULTS

Incubation of NHuK with PV sera caused their detachment from the plates after 20-30 minutes with a complete acantholysis within 12 hours. An early C3 mRNA expression was seen after 30 minutes with a peak level after 1 hour. Blocking studies, using antibodies against human IL-1alpha and TNF-alpha in NHuK together with PV-IgG, showed reduction of in vitro induced acantholysis and inhibition of C3 mRNA expression.

CONCLUSION

This study supports the hypothesis that complement C3 is important in PV acantholysis and that complement activation is increased by IL-1alpha and TNF-alpha.

The combined inactivation of tumor necrosis factor and interleukin-6 prevents induction of the major acute phase proteins by endotoxin

The constellation of changes known as the acute phase response (APR) is a cytokine-driven process initiated by tissue inflammation. The proinflammatory cytokines, TNF, IL-1 and IL-6, are considered to be the primary mediators of the APR. IL-6 and IL-1beta gene-deleted mice (Fattori et al., J. Exp. Med. 1994. 180: 1243-1250; Kopf et al., Nature 1994. 368: 339-342; Fantuzzi et al., J. Immunol. 1996. 157: 291-296, respectively), exhibit impaired APR to turpentine injection but only a slight reduction in plasma acute phase protein levels in response to lipopolysaccharide (LPS). This infers an important role for TNF in the LPS-induced APR, however, in the present study, normal APR to both turpentine and LPS were observed in TNF/LTalpha-deficient mice. A striking absence of elevated major acute phase proteins, SAP and SAA, was observed in mice deficient in TNF/LTalpha and IL-6, suggesting that TNF-alpha or LTalpha do indeed exert important nonredundant synergism in the IL-1/IL-6 primary response. The regulation of other parameters typically altered in an APR, body weight, blood glucose and haptoglobin, was normal in LPS-dosed TNF/LTalpha-deficient and wild-type mice. The observed transcriptional response for SAA and SAP in these TNF/LTalpha/IL-6-deficient mice, in lieu of elevated plasma levels, suggests that SAA and SAP expression is possibly posttranscriptionally regulated.

Anti-CD14 mAb treatment provides therapeutic benefit after in vivo exposure to endotoxin

The presence of endotoxin from Gram-negative bacteria signals the innate immune system to up-regulate bacterial clearance and/or killing mechanisms. Paradoxically, such responses also contribute to septic shock, a clinical problem occurring with high frequency in Gram-negative septicemia. CD14 is a receptor for endotoxin (lipopolysaccharide, LPS) and is thought to have an essential role in innate immune responses to infection and thereby in the development of septic shock. Using a novel rabbit model of endotoxic shock produced by multiple exposures to endotoxin, we show that anti-rabbit CD14 mAb, which blocks LPS-CD14 binding, protects against organ injury and death even when the antibody is administered after initial exposures to LPS. In contrast, anti-rabbit tumor necrosis factor mAb treatment fails to protect when administered after LPS injections. These results support the concept that anti-CD14 treatment provides a new therapeutic window for the prevention of pathophysiologic changes that result from cumulative exposures to LPS during septic shock in man.

Differences among acute, subacute, and chronic chorioamnionitis based on levels of inflammation-associated proteins in cord blood

The serum concentration of inflammation-associated proteins and several complement components in the cord blood of 215 newborns with and without chorioamnionitis (CAM), who were delivered between 17 and 42 weeks of gestation, were measured. We investigated the relationship of levels of serum proteins to acute, subacute, and chronic CAM, and to subacute necrotizing funisitis (SNF). Complement components C3d, C3, and C4 levels increased in subacute CAM (P = 0. 0002, P = 0.0007, P = 0.0029, respectively), whereas factor B increased in each type of CAM (P = 0.0001, P = 0.0009, P = 0.0004, respectively). Among the immunoglobulins, IgG levels were unrelated to the presence or type of CAM, IgM levels increased in subacute CAM (P < 0.0001), and IgA levels increased in chronic CAM (P < 0.0001). Among the acute phase reactants (APR), haptoglobin and C-reactive protein (CRP) levels increased in acute (P < 0.0001, P = 0.0022, respectively) and chronic CAM (P = 0.0035, P = 0.0345, respectively), whereas orosomucoid levels increased in chronic CAM (P = 0.0003). IL-6 levels increased in acute (P = 0.0011) and subacute (P = 0. 0475) CAM. C3d (P = 0.0063), C3 (P = 0.0289), C4 (P = 0.0491), and IgM (P < 0.0001) levels were increased in SNF. These findings suggest that the histologic distinction of acute, subacute, and chronic CAM is a useful indicator of the inflammatory mediator status of the infants. The infants with SNF may have ended their initial active inflammatory states, but they still have subacute immune activation.

Bruton's tyrosine kinase expression and activity in X-linked agammaglobulinaemia (XLA): the use of protein analysis as a diagnostic indicator of XLA

Mutations in the Bruton's tyrosine kinase (BTK) gene result in XLA. Despite the large numbers of BTK mutations reported, no correlation can be made between the clinical phenotype and the gene defects. Analysis of Btk protein expression and activity in individuals with XLA was performed to characterize the relationship between a particular mutation, the resultant Btk protein and the clinical phenotype. In most patients studied, including those with atypical phenotypes, there was complete absence of protein expression and activity. Furthermore, in two undiagnosed individuals with a clinical phenotype suggestive of XLA, lack of protein expression was used to confirm an abnormality in Btk. These results underline the importance of protein analysis prior to speculating on protein structure and function based on the gene mutation. Lack of Btk expression in atypical phenotypes suggests that there is redundancy in B lymphocyte signalling such that alternative signalling molecules, or mechanisms, can compensate for the lack of Btk. We also suggest that analysis of Btk expression can be used as an indicator of XLA. These rapid assays may be used to screen a wider spectrum of individuals with humoral immunodeficiency in order to characterize fully the extent of Btk deficiency.

Interleukin-6-dependent and -independent regulation of the human C-reactive protein gene

We have investigated the function of different mediators of the regulation of the human C-reactive protein (hCRP) gene in transgenic mice. hCRP was induced by lipopolysaccharide and wounding in interleukin-6 (IL-6) +/+ mice, but not in IL-6 -/- mice. This finding suggested that IL-6 is necessary for the induction of hCRP. However, injection of IL-6 did not induce the hCRP gene. Thus, the induction of hCRP by IL-6 seems to require an additional cofactor. Therefore, we screened different cytokines for their activity in IL-6 +/+ and IL-6 -/- mice. Surprisingly, interleukin-1beta, as well as oncostatin M or leukaemia inhibitory factor, led to an induction of hCRP in both genetic backgrounds. These results indicate an IL-6-dependent and -independent regulation of hCRP. These hCRP transgenic mice therefore represent a novel model system for defining the cytokine network involved in the regulation of acute-phase genes during the course of inflammation.

Secretion of the C3 component of complement by peritoneal cells cultured with encapsulated Cryptococcus neoformans

Two isolates of Cryptococcus neoformans were identified as being widely divergent in pathogenic potential after intratracheal infection of mice. These isolates differed in their ability to upregulate capsule synthesis when grown under tissue culture conditions, and this property correlated with virulence. We postulated that differential capsule synthesis may cause differential stimulation of macrophages to produce products such as complement components. To test this hypothesis, heat-killed yeast cells were incubated with normal mouse peritoneal cells (PC) before the level of C3 secreted was determined. Cryptococcal stimulants were grown on mycological agar, which does not promote capsule synthesis, or in RPMI 1640 at 37 degrees C in an atmosphere of 5% CO2, which stimulates capsule synthesis, to determine the role that the capsule plays in the induction of C3 secretion. C3 levels were elevated in cultures containing cryptococci grown in RPMI 1640 at 37 degrees C in an atmosphere of 5% CO2, and the level of C3 detected was correlated with the amount of capsule expressed by the yeast cell stimulant. Nonencapsulated mutants of C. neoformans did not stimulate C3 secretion. Purified capsular polysaccharide (glucuronoxylomannan [GXM]) also stimulated the PC to secrete C3. Two signals were required before GXM stimulated C3 secretion. The second signal was identified as endotoxin present in small amounts (0.06 ng per ml) in tissue medium. Endotoxin may provide a priming stimulus for PC to express receptors or other cytokines needed for effective stimulation of C3. These experiments show that enhancement of C3 secretion by C. neoformans is due to GXM and is correlated with the virulence of the cryptococcal isolate.

Interleukin-6 is necessary, but not sufficient, for induction of the humanC-reactive protein gene in vivo

We have investigated the involvement of interleukin-6 (IL-6) in the induction of the gene encoding the acute-phase protein human C-reactive protein (hCRP). In transgenic mice the hCRP gene can be induced by lipopolysaccharide (LPS), but not by IL-6. In contrast, hCRP was inducible by IL-6 in primary human hepatocytes and in primary hepatocytes isolated from transgenic mice. To further evaluate the role of IL-6, we introduced the hCRP transgene into animals lacking endogenous IL-6 (IL-6-negative mice). Here, hCRP was not inducible by LPS, but was induced by a combination of LPS and IL-6. These results clearly demonstrate that IL-6 is necessary, but not sufficient, for the induction of hCRP expression. These animal models will allow further dissection of the cytokine network responsible for the regulation of the major human acute-phase reactant CRP.

Characterization of complement C3, C4, and factor B molecules in human bile

We performed molecular analysis of complement components (C3, C4, and factor B) in human bile by sodium dodecyl sulfate-polyarylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Complement C3 was detected as a molecule composed of a 115-kDa alpha-chain linked to a 70-kDa beta-chain by disulfide bonds, and C3 levels ranged from 45 to 650 micrograms/ml (n = 15). C4 was detected as a triple chain (98-kDa alpha-chain, 73-kDa beta-chain, and 33-kDa gamma-chain) molecule linked by disulfide bonds, and C4 levels ranged from 2.5 to 60 micrograms/ml. Factor B, a component of the alternative pathway, was also detected, as an intact form. Factor B levels ranged from 0.3 to 8.0 micrograms/ml. The sizes and subunit structures of complement components in human bile were compatible with those reported in human serum. The results of a hemolytic assay indicated that complement molecules in human bile were functionally active. These molecules may participate in local immune and inflammatory responses in the biliary tract.

C3 production of cultured human epidermal keratinocytes is enhanced by IFNgamma and TNFalpha through different pathways

We investigated the regulation of C3 production by human cultured epidermal keratinocytes by enzyme-linked immunosorbent assay. The results showed that IFNgamma and TNFalpha enhanced the synthesis of C3 by epidermal keratinocytes in a concentration-dependent manner. Moreover, a protein kinase C (PKC) inhibitor blocked C3 production, whereas PMA enhanced it. There was a synergistic effect between IFNgamma and TNFalpha. In experiments to investigate the role of protein tyrosine kinase (PTK) in C3 production, we found that treatment with herbimycin A, a specific inhibitor for the c-Src-related PTK, caused significant enhancement of the C3 production induced by IFNgamma or TNFalpha, suggesting that c-Src-type PTK(s) provides a negative signal to C3 production. Each competitive inhibitor of PTK, genistein or tyrphostin, substantially increased the C3 production by IFNgamma at lower concentrations, although each agent had little effect on TNFalpha-associated production of C3 at the same concentrations. The data show that pro-inflammatory cytokines IFNgamma and TNFalpha synergistically augment C3 production by epidermal keratinocytes by different pathways.

Alternative assay procedures for cytokines and soluble receptors of the IL-6 family

Human hepatoma cells (HepG2 cells) were transfected with expression vectors for human IL-6 (hIL-6) and rat IL-6R (rIL-6-R). The cell lines were used for testing the biological activity of different IL-6 species, soluble hIL-6R (shIL-6R) and some members of the IL-6 cytokine family by means of an ELISA procedure. The assay is based on induction of the gene expression of the acute phase protein haptoglobin in hepatoma cells and provides an alternative bioassay taking advantage of the hepatocyte stimulatory activity of IL-6 (as opposed to the B9 proliferative assay). A dose-response experiment with IL-6 showed that half-maximal stimulation was achieved with approx. 5 ng/ml of hIL-6 in HepG2 cells and with 5-10 ng/ml muIL-6 in HepG2-rIL-6R cells after 24 h. The same response was achieved with 10 ng/ml shIL-6R in HepG2-IL6 cells. In conclusion, the assay is fast and reliable and might be adopted for other cytokines and receptors with hepatocyte stimulating activity.

Production of cytokines and prostaglandin E2 by subpopulations of guinea pig enterocytes: effect of endotoxin and thermal injury

BACKGROUND

There is increasing evidence that cells other than immune cells have the potential for producing immunomediators. This study determined whether distinct populations of enterocytes from unburned and burned animals responded differently to endotoxin regarding production of tumor necrosis factor, interleukin-1 and -6 and prostaglandin E2.

METHODS

Three subpopulations of enterocytes, progressing from the villus tip towards the crypt, were obtained from washes of the small intestine. The cells were cultured in the presence of endotoxin, and the supernatants were assayed for the mediators.

RESULTS

Thermal injury primed all three populations of enterocytes to produce larger amounts of tumor necrosis factor and interleukin-6 compared to cells from unburned animals. Enterocytes that were nearer the crypt produced the largest amounts of the cytokines.

CONCLUSION

These observations may be important because, as gut integrity is compromised after thermal injury, enterocytes that may have previously been unexposed or less exposed to endotoxin can become a significant source of inflammatory cytokines.

Molecular cloning and sequencing of interleukin 6 cDNA fragments from the harbor seal (Phoca vitulina), killer whale (Orcinus orca), and Southern sea otter (Enhydra lutris nereis)

Using polymerase chain reaction, interleukin-6 (IL-6) cDNA fragments from harbor seal (Phoca vitulina), killer whale (Orcinus orca), and Southern sea otter (Enhydra lutris nereis) were cloned and sequenced. For all three species, a continuous open reading frame encoding 203 residues for harbor seal, 199 residues for killer whale, and 201 residues for sea otter with stop codons located at analogous positions were identified. These fragments correspond to nucleotides 71 - 753 of the human IL-6 transcript and represent 96% of the complete coding nucleotides. Comparison of these marine mammal sequences with other published mammalian IL-6 cDNA demonstrated that both harbor seal and sea otter IL-6 had most similarity to that of other terrestrial carnivores (Mustelidae and Canidae), while killer whale had highest identity with ruminants (Bovidae and Ovidae). Among the three marine mammal species characterized, as well as cDNA sequences from nine other species, 40 invariant amino acids, including a number of residues situated at the putative gp80 and gp130 receptor binding sites, were identified. The presence of invariant amino acids within the receptor-binding portion of IL-6 for twelve different species suggests these positions are essential for biological activity of IL-6 and, moreover, likely account for the cross-reactivity among different mammalian IL-6-like activities in mouse bioassays. An additional significant finding was the presence of several variant residues only within the mouse putative IL-6 receptor binding region, which may account for observations of restricted cross-reactivity of mouse IL-6-like activity in human bioassays. Together, these findings provide insights into the evolution of the mammalian IL-6 gene and additional valuable information regarding amino acid residues essential for the biological activity of mammalian IL-6.

Histopathology of acetaminophen-induced liver changes: role of interleukin 1 alpha and tumor necrosis factor alpha

Administration of 500 mg/kg acetaminophen (APAP) to female B6C3F1 mice resulted in well-documented pathophysiological changes in the liver manifested as increased serum concentration of liver enzymes (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and serum sorbitol dehydrogenase), centrilobular congestion, and hepatocellular degeneration and necrosis. The role of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-alpha) and interleukin 1 alpha (IL-1 alpha), on the hepatotoxicity of APAP was examined at 4, 8, 12, and 24 hr following APAP administration. Neutralization of TNF-alpha or IL-1 alpha with specific antibodies partially prevented the hepatotoxic effects of APAP at the 4- and 8-hr time points. In addition, prior administration of anti-TNF-alpha antibodies shortened the recovery time following APAP treatment. While IL-1 receptor antagonist (IL-1ra) had only a modest protective effect against APAP-induced liver damage, as determined by serum enzyme release, IL-1ra had no effect on the degree of hepatic congestion or necrosis at any of the time points examined. On the other hand, administration of antibodies against IL-1ra exacerbated APAP-induced liver toxicity. These results suggest that TNF-alpha and IL-1 alpha play an important role in the degree of damage and recovery that the liver undergoes following APAP intoxication.

Inflammatory effects of peritoneal dialysis: evidence of systemic monocyte activation

We evaluated in peritonitis-free patients undergoing continuous ambulatory peritoneal dialysis (CAPD) the release of both interleukin-6 (IL-6) and beta-2-microglobulin (beta 2m) by cultured peripheral blood mononuclear cells (PBMC), as well as the levels of serum amyloid A (SAA), that is, the main hepatic acute phase protein during inflammation. The same measurements were obtained in hemodialysis (HD) patients, uremic non-dialyzed patients (ESRD) and healthy controls (CON). In CAPD, IL-6 production from PBMC was markedly increased in comparison to the control value (600.7 +/- 104.3 vs. 14.2 +/- 3.6 pg/3 x 10(6) PBMC/24 hr, P < 0.005). Similarly, a striking enhancement of the PBMC release of beta 2m was detected in CAPD with respect to CON (10.1 +/- 2.6 vs. 0.063 +/- 0.013 micrograms/3 x 10(6) PBMC/24 hr, P < 0.001). Also, the SAA levels were significantly greater in CAPD patients (21.3 +/- 8.7 micrograms/dl) than in controls (3.14 +/- 0.17 micrograms/dl, P < 0.05). Analogous increases of both IL-6 and beta 2m cell releases, as well as of SAA levels, were observed in HD patients. No difference concerning the three parameters was detected between CON and ESRD. In conclusion, CAPD induces per se PBMC activation with an enhanced release of both IL-6 and beta 2m; this is associated to higher levels of SAA. These systemic inflammatory effects are comparable to those observed in HD patients indicating that CAPD is similar to HD in terms of biocompatibility of the treatment.

Drugs affecting plasma fibrinogen levels. Implications for new antithrombotic strategies

Current evidence indicates that plasma fibrinogen is synthesized by the liver; that genetic and environmental factors regulate plasma fibrinogen levels; that interleukin-6 (IL-6) affects the synthesis of plasma fibrinogen by mechanisms involving protein kinase C, and that during the acute-phase response, monocytes generate a variety of monokines including IL-6. Certain drugs and nutrients have been reported to lower plasma fibrinogen levels. The mechanism(s) involved in this effect is poorly understood. However, since most of these substances quantitatively and/or qualitatively affect monocytes, the possibility that these drugs affect plasma fibrinogen levels via these cells should be considered. In addition to fibrinogen, IL-6 also regulates the synthesis of other acute-phase proteins. Especially when combined, major risk factors for atherosclerosis cause vascular injury that triggers inflammatory events. This raises the issue of whether high plasma fibrinogen levels are just the epiphenomenon of as yet unknown events in thrombosis and atherosclerosis. Thus, the issue to be addressed is whether high plasma fibrinogen concentrations should be lowered or should they serve to suggest strong interventions on established risk factors. As for other risk factors, fibrinogen measurements in population-based studies, in parallel with measurements of established risk factors will help define appropriate directions to be followed to gain insight into the issue and define new antithrombotic strategies.

Predictors of 2-year mortality among older male veterans on a geriatric rehabilitation unit

OBJECTIVE

To determine if nutritional parameters and discharge setting are associated with mortality in older male veterans on a Geriatric rehabilitation unit (GRU).

DESIGN

Two-year follow-up of sequential admissions to the GRU who had laboratory studies completed on admission to the acute hospital and on transfer to and discharge from the GRU.

SETTING

University-affiliated VA medical center.

PATIENTS

Eighty-three consecutive older male veterans admitted to the GRU.

MEASUREMENT

Mortality during a period of 2 years post-discharge.

MAIN RESULTS

In a univariate analysis, predictors of mortality were serum albumin level < or = 3.5 g/dL on admission to the GRU (P = .01), moderate or severe Nutritional Status Score (P = .03), discharge to a place other than home (P = .01), and use of antibiotics while on the GRU (P = .05). Discharge albumin remained the single significant predictor of mortality in a multivariate analysis (P = .005).

CONCLUSIONS

Serum albumin is the strongest predictor of 2-year post-hospitalization mortality of older patients cared for on a GRU. Other predictors were presence of infection, Nutritional Status Score of moderate or severe compromise, and discharge to a place other than home.

Microheterogeneity of acute phase proteins in patients with clinically active and clinically nonactive osteoarthritis

Microheterogeneity of two acute phase glycoproteins, alpha-1-acid glycoprotein (AGP) and alpha-1-antichymotrypsin (ACT), concentrations of AGP, ACT, and C-reactive protein (CRP), and levels of three cytokines: interleukin 1 beta (IL-1-beta), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) were determined in 61 serum samples and 7 synovial fluids (SFs) obtained from patients (n = 61) with osteoarthritis. Using affinity immunoelectrophoresis with concanavalin A (conA), a significant decrease in the reactivity of AGP and ACT with this lectin was found in patients with clinically active osteoarthritis when compared to those with clinically nonactive disease (p < 0.001 and p < 0.05, respectively). There was no increase in the concentration of AGP, ACT, and C-reactive protein (CRP) in the sera examined. In particular, no increase in the serum level of these proteins was found in the patients with clinically active disease. Low concentrations of IL-6 and TNF-alpha were found in most sera and SFs examined. In 6 out of 7 SFs available, IL-6 concentrations were higher than in the respective serum samples but for TNF-alpha the same could be shown in one case only. Low concentrations of IL-1-beta were found in 4 serum samples obtained from patients with clinically active osteoarthritis and in no SF specimen studied. In the entire group, serum level of TNF-alpha correlated weakly with the AGP and ACT reactivity coefficients with conA (r = 0.3634, p < 0.005 and r = 0.3324, p < 0.02, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical demonstration of interleukin-1 beta induced changes in acute-phase proteins and albumin in rat liver

Interleukin-1 beta is a potent mediator of the acute-phase response. However, the effects of interleukin-1 beta administration on the topic in vivo production of acute-phase proteins and albumin are so far not well understood. Overnight fasted rats were subcutaneously injected with 0.2 mL 0.9% NaCl (control group) or 6.25 micrograms recombinant human interleukin-1 beta, and rectal temperature was measured at intervals up to 48 h. Livers were perfused-fixed in vivo prior to injection (base-line), and at 9, 24, and 48 h following the interleukin-1 beta injection. Fibrinogen, orosomucoid (alpha 1-acid glycoprotein) and albumin were immunostained using a streptavidin-biotin-immunoperoxidase technique. Rectal temperature peaked 5 h after the single interleukin-1 beta injection, and fell gradually to base-line values by 24 h. Prior to injection only a few hepatocytes, randomly scattered throughout the liver lobule, stained positive for fibrinogen and orosomucoid. In contrast, all hepatocytes stained uniformly positive for fibrinogen and orosomucoid 9 h after interleukin-1 beta injection, whereas at 24 h a predominant centrilobular staining pattern occurred. Due to fasting, albumin positive hepatocytes were already reduced at base-line in both groups. Interleukin-1 beta induced a further significant loss of albumin positive cells in the periportal zone (35 +/- 21%) at 9 h when compared with controls (58 +/- 11%, p = 0.037). In conclusion, subcutaneous interleukin-1 beta (probably by stimulation of interleukin-6) strongly induces fibrinogen and orosomucoid expression in rat liver, and suppresses immunohistochemically stainable albumin in a heterogenous way, mainly in the periportal zone.

Serum levels of interleukin 6 in patients with lung cancer

Serum interleukin 6 (IL-6) levels were measured in 75 patients with lung cancer and in 20 patients with benign lung diseases. IL-6 was detectable in 29 patients with lung cancer (39%), but was not detectable in any of the patients with benign lung diseases. Serum C-reactive protein levels and plasma fibrinogen levels were significantly higher and serum albumin concentration was significantly lower in lung cancer patients with detectable serum IL-6 levels than in those without detectable serum IL-6 levels and in patients with benign lung diseases. On the other hand, no significant difference was observed in blood platelet counts in these three groups. Moreover, serum IL-6 levels were not significantly different in lung cancer patients with or without clinically demonstrated distant metastasis. These results suggest that IL-6 may be a mediator of various reactions including an inflammatory response in lung cancer patients.

Influence of an established acute phase response on the severity of experimental nephritis

Small doses of lipopolysaccharide (LPS) induced an acute phase response (APR), and a number of studies have also shown that this greatly enhances the severity of glomerular injury in the heterologous phase of nephrotoxic nephritis (hNTN), an experimental model of anti-glomerular basement membrane (GBM) disease. Here, we examined the influence of pre-existing subclinical infection and raised APR, assessed by plasma alpha 2-macroglobulin (alpha 2-M) concentration, on the degree of injury in this model of nephritis. Studies were initially performed to determine the normal range of alpha 2-M in rats and its modulation by IL-6 and different doses of LPS. Plasma concentration of alpha 2-M was found to be variable and dependent on the weight of the rats. Single injections of either LPS or IL-6 had a comparable effect, and continuous perfusions of LPS caused a progressive increase in alpha 2-M which peaked at 48 h and declined gradually over 1 week. Following induction of nephritis with 10 mg of anti-GBM antibody, rats with raised alpha 2-M had 14 +/- 3 mg/24 h albuminuria compared with 4 +/- 1 mg/24 h in rats with normal alpha 2-M (P < 0.001, Wilcoxon). Injection of 20 mg anti-GBM antibody caused 36 +/- 11 mg/24 h albuminuria compared with 16 +/- 4 mg/24 h (P < 0.001), respectively. However, all these rats remained active and none of them died. In contrast, injection of 0.25 microgram LPS before induction of nephritis with 10 mg anti-GBM antibody, in rats with raised alpha 2-M, caused severe albuminuria (115 +/- 23 mg/24 h) compared with rats having normal levels of alpha 2-M (72 +/- 15 mg/24 h, P < 0.05). Furthermore, rats with raised alpha 2-M also had severe systemic manifestations characterized by pulmonary haemorrhage and extensive glomerular thrombosis, and many of them died. These results demonstrate the potential effect of pre-existing subclinical infection and raised APR on severity of glomerular injury which may affect the outcome of experimental studies.

Cytokine and insulin regulation of alpha 2 macroglobulin, angiotensinogen, and hsp 70 in primary cultured astrocytes

Acute-phase proteins and heat shock proteins (hsp) are upregulated following exposure to a number of conditions including bacterial infection, tissue injury, or stress. We show here that alpha 2 macroglobulin (alpha 2M), angiotensinogen (AOG), and hsp 70 are regulated by cytokines in primary cultures of astrocytes. In addition, we have found that insulin modulates the effect of cytokines on these proteins. In cells treated with lipopolysaccharide (LPS) conditioned Raw media, interleukin (IL)-6, or IL-1 beta for 24 h, there was a significant decrease of alpha 2M secretion below control levels. In the absence of insulin, however, similar treatments resulted in a significant increase in alpha 2M secretion. AOG secretion increased significantly following treatment with individual cytokines either in the presence or absence of insulin, but conditioned media did not cause a response in the absence of insulin. Hsp 73 concentrations also increased following treatment with conditioned media and IL-1 beta in the presence or absence of insulin. Following IL-6 treatment, however, hsp levels either decreased (- insulin) or did not change (+ insulin). To determine whether acute-phase proteins are regulated similarly to hsp, astrocytes were subjected to elevated environmental temperatures. Cells incubated at 43 degrees C for 90 min showed a marked increase in AOG secretion. However, alpha 2M and hsp 73 levels remained unchanged. In the absence of insulin, heat shock caused a significant increase of alpha 2M and AOG secretion. Thus, in astrocytes, alpha 2M is upregulated by cytokines and heat shock in the absence of insulin, while in the presence of insulin, cytokines function as negative regulators.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneity of Kupffer cells and splenic, alveolar, and peritoneal macrophages for the production of TNF, IL-1, and IL-6

Kupffer cells and alveolar, splenic, and peritoneal macrophages from normal rats were incubated for various periods of time in the presence of LPS, and the culture supernatants were analyzed for IL-6, IL-1, and TNF. There was very little difference in the amounts of the cytokines produced by the macrophages when stimulated with 0.01-10 micrograms/ml of LPS. The shapes of the time course curves for the production of the cytokines by the different types of macrophages were generally similar, although only Kupffer cells continued to produce IL-6 throughout the entire incubation period and splenic macrophages showed a lag period in the production of IL-1. Kupffer cells produced more IL-6 than that produced by the other populations of macrophages, and alveolar macrophages produced more IL-1 compared to that produced by splenic cells. Kupffer cells and peritoneal macrophages produced more IL-6 in 24 h than in 6 h of culture, and splenic macrophages produced more IL-1 in 24 compared to 6 h of culture. Alveolar macrophages produced more TNF than that produced by the other populations of cells but only when integrated over the entire incubation period. These results confirm and extend the observed functional heterogeneity of macrophages obtained from different tissues of the same animal. This study and future studies will lead to a better understanding of the role of cytokines in the inflammatory response.

Changes in body temperature and circulating levels of interleukin-6 after intra-arterial injections or infusions of tumor necrosis factor alpha in guinea pigs

Tumor necrosis factor alpha (TNF) is released systematically during the early phase of endotoxin induced fever. To study the effects of this cytokine in guinea pigs, 2 micrograms TNF were intra-arterially injected as a bolus or slowly infused within 60 min. Both modes of administration induced a biphasic elevation of the animals' abdominal temperature lasting 6 h and stimulated the release of endogenous interleukin-6 (IL-6)-like activity. The second phase of the thermal response and the release of endogenous IL-6-like activity were significantly higher, when TNF was slowly infused into the animals' circulation, in spite of a transiently higher TNF-like activity after the bolus injection of TNF. Both TNF and IL-6 may therefore be regarded as candidates to trigger the febrile response in guinea pigs.

Do high levels of C-reactive protein in Tanzanian children indicate malaria morbidity

Children under 6 years of age living in an area of Tanzania highly endemic for malaria were tested for C-reactive protein (CRP) in order to determine how the acute-phase response is related to malaria in children of different ages and to investigate whether serum CRP concentrations might be useful in the qualification of morbidity in such children. The median CRP level in the 629 finger-prick blood samples measured, 6.0 mg/liter, was much higher than that reported in the blood of children in Europe. The CRP concentration was correlated with recent illness reported by the parents. High CRP levels were most strongly associated with Plasmodium falciparum parasitemia in children under 1 year of age. In older children, lower levels of CRP were associated with parasitemia, and fewer children had increased CRP levels attributable to parasitemia. The levels of malaria-attributable CRP appear to track the acquisition of parasitological and clinical tolerance in this area with very high levels of P. falciparum transmission. Determination of CRP levels should be useful in the rapid assessment of the overall burden of morbidity, especially in infants. In areas where malaria is endemic, CRP associated with increased parasite densities provides an objective measure of malaria-specific morbidity. This would be an efficient approach to estimating malaria morbidity risks from small-scale serological surveys.

Control of activator protein-1 and nuclear factor kappa B activity by interleukin-1, interleukin-6 and metals in HEPG2 cells

The intracellular signals induced by IL-1 and IL-6 have been described but there are few details of the signals they induce in liver-derived cells during initiation of acute phase protein synthesis. We therefore used an in vitro system to investigate signalling by IL-1 and IL-6 in the human liver cell line, HepG2. Chloramphenicol acetyl transferase (CAT) expression vectors, under the control of activator protein-1 (pTRE-CAT), nuclear factor kappa B (pNF-CAT) or no enhancer region (pBLCAT2), were transfected into HepG2 cells and the effects of the cytokines on their activity was studied. Profound changes in liver processing of heavy metals and the induction of metal-dependent acute proteins are also seen during the acute phase response. To determine if the supply of metal ions could itself influence signalling we also investigated the effects of cadmium and zinc on the activity of the transfected vectors. Both alpha and beta forms of interleukin-1 increased the expression of pTRE-CAT and pNF-CAT, but not pBLCAT2, while interleukin-6 had no effect, suggesting that activator protein-1 and nuclear factor kappa B activity was induced by interleukin-1, but not interleukin-6. Specificity of the effect of interleukin-1 alpha was confirmed using an anti-interleukin-1 alpha monoclonal antibody. Zinc and cadmium also increased pTRE-CAT expression, but not pNF-CAT or pBLCAT2. Removal of heavy metal ions from the culture medium resulted in decreased pTRE-CAT expression, while pNF-CAT and pBLCAT2 were relatively unaffected, confirming the stimulatory effect of metals on activator protein-1, but not nuclear protein kappa B activity. Therefore, metal and interleukin-1-mediated signal transduction may involve overlapping pathways, whereas interleukin-1 and interleukin-6 act via different pathways in liver cells.

Interleukin-6 enhances hepatic transferrin uptake and ferritin expression in rats

To explore a mechanism of interleukin (IL)-6-induced hypoferremia in rats, iron metabolism was investigated both in vivo and in vitro. Recombinant IL-6 was intraperitoneally administered to male Wistar rats and the serial change of parameters related to iron metabolism was examined. After administration of IL-6, plasma IL-6 concentration increased rapidly, reached its maximum in 1 hr and thereafter decreased quickly. Plasma IL-6 3 hr after IL-6 injection (50 micrograms/kg) was 3 units/ml, which is a concentration capable of inducing hepatic 125I-labeled transferrin uptake in vitro using isolated hepatocytes. Plasma iron concentration and transferrin saturation had decreased to approximately one third of the initial level within 3 hr and then recovered. Total iron binding capacity remained unchanged for 6 hr, then began to decrease. Red blood cell count and hemoglobin concentration showed no remarkable changes during this period. By ferrokinetic study with plasma that contained iron 59-labeled transferrin, the plasma iron disappearance half time, calculated from the disappearance curve, was significantly shortened from 55 min to 22 min by IL-6 treatment (p < 0.01). The ferritin concentration in the liver was increased significantly after the administration of IL-6 (p < 0.001), but transiently decreased in the spleen. The plasma ferritin showed a gradual increase during the 6-hr period after IL-6 injection. The uptake of 125I-labeled diferric transferrin by isolated hepatocytes was increased by IL-6 treatment and this increment was inhibited by addition of 100-fold excess unlabeled transferrin. On the other hand, no significant increment of 125I-labeled diferric transferrin uptake was observed in Kupffer cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcapillary escape rate of albumin positively correlates with plasma albumin concentration in acute but not in chronic inflammatory disease

The relationship among "negative" plasma acute-phase proteins (APP), ie, albumin, prealbumin, and transferrin, and "positive" APP, ie, C-reactive protein (CRP), fibrinogen, and orosomucoid, was investigated in patients with acute infectious disease (n = 8) and in patients with chronic malignant disease (n = 9). In addition, the transcapillary escape rate (TER) and outflux (J(alb)) of albumin were investigated using an intravenous injection of 2 microCi 125I-albumin. Interleukin-6 (IL-6) plasma concentrations were measured with an enzyme immunoassay. In the majority of patients, negative APP were decreased, whereas positive APP were increased. However, in patients with infectious disease, there were no significant correlations between any of the negative and positive APP. Also, in patients with infectious disease, TER was increased to 8.6 +/- 3.4%/h (mean +/- SD), and J(alb) to 114 +/- 60 mg/kg/h, compared with normal values of 4.3 +/- 2.6%/h and 108 +/- 7 mg/kg/h, respectively. Unexpectedly, there was a significant positive correlation between plasma albumin and both TER (r = .8279, P = .011) and J(alb) (r = .8683, P = .005). In patients with malignomas, significant correlations within negative and positive APP and inverse correlations between negative and positive APP resulted. Malignant disease induced only a slight elevation in TER (6.6 +/- 2.4%/h), J(alb) was within normal limits (92 +/- 35 mg/kg/h), and no correlations between plasma albumin concentrations and TER (r = -.0174, P = .97) or J(alb) (r = .4090, P = .27) were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of haptoglobin expression in IL-6 treated HepG2 cells by ELISA and by RNA hybridization--evaluation of a quantitative method to measure IL-6

Interleukin-6 (IL-6) is known to be an important modulator of acute phase (AP) protein expression in hepatocytes both in vivo and in vitro. In the present study the inducing activity of IL-6 on the expression of the AP protein haptoglobin (HP) by the human hepatoma cell line HepG2, has been evaluated. HP mRNA inducibility was analysed by Northern and slot-blot hybridization, while HP protein was detected by means of an ELISA procedure. A dose-response relationship from 0.3 to 4.8 ng/ml of a human recombinant IL-6 preparation derived from a Chinese hamster ovary (CHO) cell line was observed after 48 h of treatment. Comparable results were obtained by analysing both HP mRNA expression and HP protein secretion. Detectable induction of HP protein secretion was observed with as little as 25 pg/ml of IL-6. The effect of IL-6 was potentiated by dexamethasone, while an inhibition on HP mRNA inducibility could be prevented by lowering the foetal calf serum (FCS) concentration to 1%. Preliminary data indicate that neither IL-1 beta nor TNF-alpha were able to induce significantly HP mRNA expression and protein secretion. The activity ratio between two IL-6 preparations (from CHO and E. coli cells) obtained with a conventional IL-6 bioassay (i.e., T1165 cell growth assay) was comparable to that obtained in the induction of HP expression. The nominal specific activity of the CHO-derived IL-6 was two to three times higher with both responses.

Human hepatoma cells synthesize and secrete lysozyme: modulation by cytokines

Plasma lysozyme levels are elevated in several different pathological conditions. In our study we show that well differentiated human hepatoma cells Hep3B and HepG2 are active synthesis sites of lysozyme and that this synthesis can be modulated by acute phase mediators. The production and modulation of lysozyme synthesis was studied by means of Northern-blot analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a specific bioassay after treatment of the cells with interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha. Hep3B and HepG2 cells constitutively synthesize high amounts of lysozyme. Lysozyme synthesis and secretion were found to be augmented by interleukin-1 beta and tumor necrosis factor-alpha in both cell lines. Interleukin-6 caused an increase in lysozyme production in Hep3B but a decrease in the HepG2 cells. As expected, the synthesis of albumin was decreased in both cell lines. Furthermore we demonstrated that HepG2 and Hep3B cells produce a biologically active form of the enzyme as measured by a specific bioassay. The results demonstrate that lysozyme is constitutively synthesized by Hep3B and HepG2 hepatoma cell lines and that lysozyme synthesis is modulated by acute-phase mediators. Well differentiated human hepatoma cells may respond differently to different cytokines.

Prostaglandin E2 stimulates the production of interleukin-6 by neonatal mouse parietal bones

The pleiotropic cytokine interleukin-6 (IL-6) is thought to be involved in bone homeostasis. A number of bone resorbing agents have been shown to induce the release of IL-6 from bone. We wished to determine whether prostaglandin E2 (PGE2), which is a mediator of bone resorption, can elicit the production of IL-6. IL-6 was measured by the proliferative response of B9 hybridoma cells and could be completely neutralised by an anti-IL-6 antibody. Parietal bones from neonatal mice were maintained in culture in the presence of indomethacin (10(-6) M) with or without PGE2. The time course and dose-response to PGE2 of IL-6 production were determined. After 6 h in culture, 10(-8) M PGE2 produced significantly more IL-6 than the controls (P < 0.005). PGE2 (10(-6) M) stimulated the production of a mean of 12.8 ng/ml IL-6 over 6 h. Preincubating bones with indomethacin for 20 h prior to a 6 h culture with indomethacin led to a lowering of the production of IL-6 (mean 1.8 ng/ml) compared to bones cultured without the preincubation period (5.8 ng/ml). When the indomethacin preincubation period was used, a significant increase in IL-6 production was found with 10(-9) M PGE2 (P < 0.005), and 10(-6) M PGE2 caused the production of 39.9 ng/ml IL-6 over 6 h. Stripping endocranial and ectocranial membranes from bones demonstrated the membranes to be the major site of IL-6 production. However, intact bones were required for maximal stimulated IL-6 production.

Suppressed antibody and interleukin-6 responses to acute pyelonephritis in pregnancy

This study examined the effect of pregnancy on the host response to acute pyelonephritis. Urine and serum samples were obtained at the time of diagnosis and after two weeks, from non-pregnant and pregnant women with acute pyelonephritis. The samples were analyzed for interleukin-6 (IL-6) and specific antibody activity to antigens extracted from the Escherichia coli strain infecting each patient. The host response to infection was further quantitated as fever, C-reactive protein, and renal concentrating capacity. Acute pyelonephritis in non-pregnant and pregnant women was accompanied by a significant serum and urine antibody response. The serum antibody response was significantly lower in the pregnant group. The IL-6 levels in serum and urine at diagnosis were significantly higher in the non-pregnant compared to the pregnant women. These results demonstrate that the immunosuppression of pregnancy includes the mucosal IL-6 and specific antibody responses to acute pyelonephritis caused by E. coli.

Effect of cytokines on the secretion of the fifth and eighth complement components by HepG2 cells

Liver cells can be induced by interleukin-1, tumor necrosis factor and interleukin-6 to secrete higher amounts of complement components. Information, so far available only for the early components, indicates that these cytokines exhibit different effects on various complement proteins. For instance, they promote the biosynthesis of C3 and B but have no effect on that of C4 and C2. These observations led us to evaluate the ability of interleukin-1, tumor necrosis factor and interleukin-6 to modulate the secretion of the late complement components by HepG2 cells, a human hepatoma-derived cell line known to produce several complement proteins. The amount of complement components in the culture supernatant was evaluated by a sensitive enzyme-linked immunosorbent assay revealing picogram levels of these proteins. The HepG2 cells were found to secrete a substantial amount of C3 (approximately 1 microgram/10(6) cells), easily detectable C5 (approximately 150 ng/10(6) cells) and C8 (approximately 10 ng/10(6) cells) and a low amount of C6 (approximately 0.5 ng/10(6) cells), whereas the levels of both C7 and C9 could not be measured. The addition of interleukin-1, tumor necrosis factor and interleukin-6 to the cell culture resulted in an enhanced secretion of C8, whereas that of C5 was only marginally increased. None of these cytokines had a clear effect on the secretion of C6 nor induced the production of C7 and C9.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of acute-phase proteins in interleukin-1-induced nonspecific resistance to bacterial infections in mice

Treatment with a single low dose (80 to 800 ng) of interleukin-1 (IL-1) 24 h before a lethal bacterial challenge of granulocytopenic and normal mice enhances nonspecific resistance. Since IL-1 induces secretion of acute-phase proteins, liver proteins which possess several detoxifying effects, we investigated the role of these proteins in the IL-1-induced protection. Inhibition of liver protein synthesis with D-galactosamine (GALN) completely inhibited the IL-1-induced synthesis of acute-phase proteins. GALN pretreatment abolished the protective effect of IL-1 on survival completely (neutropenic mice infected with Pseudomonas aeruginosa) or partially (nonneutropenic mice infected with Klebsiella pneumoniae). Pretreatment with IL-6, a cytokine induced by IL-1, did not reproduce the protection offered after IL-1 pretreatment, nor did it enhance or deteriorate the IL-1-enhanced resistance to infection. A protective effect of IL-1 via effects on glucose homeostasis during the acute-phase response was investigated by comparing plasma glucose levels in IL-1-treated mice and control mice before and during infection. Although glucose levels in IL-1-pretreated mice were somewhat higher in the later stages of infection, no significant differences from levels in control mice were present, and the glucose levels in control-treated animals never fell to hypoglycemic values. We conclude that the IL-1-induced nonspecific resistance is mediated neither by the induction of IL-6 nor by the effects of IL-1 on glucose homeostasis. Acute-phase proteins generated after IL-1 pretreatment, however, seem to play a critical role in the IL-1-induced protection to infection.

Interleukin 6-producing malignant mesothelioma

Systemic amyloidosis of the amyloid A (AA) type, is occasionally associated with various neoplasms, but the cause is still unclear. We obtained interleukin 6 (IL-6)-producing cells designated YO from a primary culture of a malignant peritoneal mesothelioma of epithelial type obtained from a 62-year-old woman. Post mortem examination revealed that the patient had systemic amyloidosis of the AA type. The supernatant media of YO cells, as well as recombinant human IL-6, successfully induced nonneoplastic liver cells to produce serum AA (SAA). Our data suggest that IL-6 produced by the tumor cells may have played an important role in the paraneoplastic syndrome of AA amyloidosis in this patient.

Identification and partial characterization of common seal (Phoca vitulina) and grey seal (Haliochoerus grypus) interleukin-6-like activities

Interleukin-6 (IL-6) is a pleiotropic molecule with many important immune modulatory actions. We have investigated the production of biological activity of this cytokine in two species of European seal. IL-6-like activity was detected in supernatants from cultured peripheral blood leucocytes. This IL-6-like activity had an apparent molecular weight of 17-26 kDa, similar to that of human IL-6. IL-6-like activity was also detected in plasma taken from seals with symptoms of systemic infection, but not from apparently healthy seals. Inhibition of this plasma and leucocyte derived activity was accomplished with both rabbit and goat antisera raised against recombinant human IL-6. Further investigation using polymyxin-B showed that this activity was not due to residue LPS present in the supernatants or infected plasmas.

Complement biosynthesis by mononuclear phagocytes

Mononuclear phagocytes are an important in vivo source of a wide range of complement components. They are able to rapidly up-regulate or down-regulate complement synthesis in response to many different pharmacological and biological stimuli. This ability is likely to make a significant contribution to maintaining host defences particularly in peripheral tissues. The important role of molecular biology in the study of complement biosynthesis by mononuclear phagocytes will be emphasised.

Molecular cloning and characterization of a ruminant interleukin-6 cDNA

By hybridization with a human interleukin-6 (IL-6) cDNA fragment a corresponding ruminant (ovine) cDNA was isolated from a lipopolysaccharide (LPS)-stimulated alveolar macrophage library. The nucleotide sequence of the cDNA and the predicted amino acid sequence of the protein showed significant homology to the human and murine molecules. Ovine IL-6 cDNA encodes a polypeptide of 208 amino acids that, based on analysis of human IL-6, is processed to a protein of 180 amino acids. Northern blot analysis and the 7TD1 bioassay were used to analyse regulatory aspects of IL-6 production by primary ovine fibroblasts. Both LPS and recombinant ovine IL-1 alpha were shown to induce IL-6 mRNA with peak levels occurring at 1 h post-stimulation and declining thereafter. When fibroblasts were pretreated with cyclohexamide prior to stimulation the level of induction by LPS and IL-1 alpha increased dramatically and peak levels were observed at 5 h post-stimulation. The level of secreted IL-6 increased rapidly over the first 24 h and continued to increase over the next 48 h.