The acute phase response: an overview

Extent of the acute phase response in fulminant hepatic failure

The extent of the acute phase response and the relation between acute phase proteins and cytokines in plasma was investigated in 50 patients with fulminant hepatic failure. On admission, C reactive protein was significantly higher in fulminant hepatic failure (median: 12.4 micrograms/ml, range:0.2-112 micrograms/ml) than in 20 controls (median: 0.8 microgram/ml, range: 0.3-2.9 micrograms/ml, p < 0.001). Serial measurements showed that plasma C reactive protein increased daily after admission until day 5, the end of the study period. alpha 1-Antitrypsin (AAT) (median: 69.1%, range: 27.5-124%) and fibrinogen (median: 1.10 g/l, range: 0-2.82 g/l) were significantly lower in fulminant hepatic failure on admission than in controls (AAT: median: 126%, range: 75.4-149%; fibrinogen: median 2.48 g/l, range: 1.82-3.39 g/l, p < 0.001) and did not change subsequently. Both AAT and fibrinogen were maintained at significantly higher concentrations in survivors than in those who did not. Bacterial infection occurred in 23 patients during the course of fulminant hepatic failure, but did not influence the concentrations of these three proteins. Interleukin 6 was significantly higher in fulminant hepatic failure (median: 21.2 pg/ml, range: 0-871 pg/ml) than in controls (median: 2.4 pg/ml, range: 1.5-8.2 pg/ml, p < 0.001). There was a significant correlation between interleukin 6 and the C reactive protein concentrations in patients with viral hepatitis on admission and in all patients 48 hours later, consistent with other evidence that interleukin 6 stimulates synthesis of this acute phase protein.

Acute-phase immune response: lipopolysaccharide-induced fever and sleep alterations are not simultaneously conditionable in the rat during the inactive (light) phase

Recent research has demonstrated that specific parameters of the immune system can be augmented by behavioral conditioning. These physiological alterations have been largely achieved by implementation of the conditioned taste aversion paradigm. Fever and sleep alterations are early occurrences within the acute-phase immune response to infection. The present study attempted to concurrently condition these two simultaneous, yet independent, responses. Lipopolysaccharide (LPS) was used as an unconditioned stimulus. When paired with a novel-tasting saccharin solution, a conditioned febrile response was observed. However, the somnogenic effects of LPS were not simultaneously conditionable. The conditioning of fever, as well as other interleukin-1-mediated responses, offers promise in both clinical and experimental applications.

Calcium ion binding regions in C-reactive protein: location and regulation of conformational changes

C-reactive protein (CRP) is a pentameric acute phase serum protein composed of identical 206 amino acid subunits that associate by non-covalent bonds. The biological activities ascribed to CRP are initiated by binding ligands via the single PC-binding site within each subunit. CRP binding to PC requires a conformational change in the intact pentraxin triggered by the binding of two free Ca2+ ions per subunit. Residues 134-148 of each subunit were previously implicated by indirect measures as one of the Ca(2+)-binding sites. In this study, 45Ca2+ autoradiography revealed that fragments of CRP of 6.5 and 16 kDa generated by proteolysis between residues 146 and 147 bind Ca2+ indicating that a second Ca(2+)-binding site is located within the C-terminal 60 amino acids. Synthetic peptides corresponding to residues 134-148 and 152-176 both bound 45Ca2+ in equilibrium dialysis experiments with a Kd = 5.2 x 10(-4) and 1.7 x 10(-4) M, respectively. The addition of Ca2+ to peptide 152-176 induced a shift in the CD-spectra between 210 and 230 nm. Rabbit anti-peptide 152-176 antibody (Ab) inhibited the availability of an epitope within the PC-binding site of CRP recognized by mAb EA4-1. Reactivity of CRP with both anti-peptide 134-148 mAb and anti-peptide 152-176 Ab enhanced the expression of the PC-binding site epitope. The results suggest that the two distinct Ca(2+)-binding sites within each CRP subunit are composed of residues 134-148 and 152-176 and that these two nearly adjacent sites cooperate to exert an allosteric change in conformation allowing access to the PC-binding site.

Cell attachment peptide of C-reactive protein: critical amino acids and minimum length

Human C-reactive protein (CRP) is an acute phase blood component that accumulates at sites of tissue damage and necrosis and is degraded by neutrophils to biologically active peptides. A dodecapeptide composed of amino acids 27-38 of CRP mediates cell attachment in vitro. This peptide was designated the cell-binding peptide (CB-Pep) of CRP. Characterization of the interaction between fibroblasts and modified synthetic peptides with sequential deletions from either the N-terminus or C-terminus revealed that the minimal sequence for cell attachment or inhibition of cell attachment to the CB-Pep was Phe-Thr-Val-Cys-Leu, which corresponds to residues 33-37 within each of the five 206 amino acid subunits of CRP. The pentapeptide by itself mediated cell attachment. Substitutions for each residue within the CB-Pep indicated that the critical residues for activity were Phe-33 and Thr-34. This cell-binding pentapeptide represents a recognition motif for cell adhesion not found in other proteins.

Altered Zn status by alpha-hederin in the pregnant rat and its relationship to adverse developmental outcome

The hypothesis that an acute-phase reaction in the pregnant animal causes a systemic redistribution of Zn, resulting in a transient but developmentally adverse Zn deficiency in the embryo, was tested by treating pregnant rats during organogenesis with alpha-hederin, an agent reported to induce substantial metallothionein (MT) synthesis in rat liver, and determining hepatic MT concentration, hepatic and plasma Zn concentration, and systemic distribution of a pulse of 65Zn after treatment. Developmental toxicity was assessed by evaluating morphologic development in term fetuses. A single dose of alpha-hederin, injected sc at dosages of 3 to 300 mumol/kg, caused an acute phase response, indicated by decreased Fe and Zn, and increased Cu, alpha 1-acid glycoprotein, and ceruloplasmin concentration in plasma, along with a dosage-related increase in maternal hepatic MT concentration. The maximum induction of MT was 11 to 15-fold greater than control and occurred at dosages of 30 mumol/kg and higher, and MT concentration reached its peak 12 to 24 h after treatment. Zn concentration in liver and liver cytosol increased along with MT, reaching a maximum level at dosages of 30 mumol/kg and higher. Plasma Zn concentration decreased after alpha-hederin treatment to a level approximately 75% of control at a dosage of 30 mumol/kg and 50% of control at 300 mumol/kg. Therefore, hepatic MT induction was associated with most, but not all, of the decrease in plasma Zn concentration. Zn distribution was evaluated by giving an oral pulse of 65Zn 8 h after treatment with 0, 30, or 300 mumol/kg alpha-hederin on gestation day 11, and measuring 65Zn levels 18 h after treatment. The fraction of 65Zn distributed to the liver of treated rats (either dosage) was twice that of control, but distribution of 65Zn to other maternal tissues was decreased. 65Zn accumulation by conceptuses was significantly decreased, attributable to decreased accumulation in decidua, but not in visceral yolk sacs or embryos; however, at this stage of development the decidua accounts for a greater quantity of Zn than either of the other products of conception and may serve as the Zn-storing tissue for the conceptus. Both 30 and 300 mumol/kg increased resorption incidence, and 300 mumol/kg also decreased fetal weight and increased the incidence of abnormal fetuses. Serum collected from rats two hours after alpha-hederin treatment (i.e., before the onset of MT synthesis) supported rat embryo development in vitro, whereas serum collected 18 h after treatment did not. Adding Zn to this serum restored normal embryonic development.(ABSTRACT TRUNCATED AT 400 WORDS)

Nutritional status of children with leukemia

Children with cancer represent a high-risk group for protein-energy malnutrition due to side effects associated with treatment. Assessment of nutritional status at the time of diagnosis and during treatment is, therefore, essential for planning nutritional intervention. We studied the nutritional status of 25 children with leukemia [9 newly diagnosed/relapsed (D/R) leukemic patients and 16 children with leukemia in remission (REM)]. Plasma proteins (prealbumin, PA; albumin, Alb; transferrin, Tr; retinol-binding protein, RBP) and acute phase-reactant proteins (alpha 1-acid glycoprotein, AGP; C-reactive protein, CRP; ceruloplasmin, CER) were measured by radial immunodiffusion. Results show that there were no significant deficits in anthropometric measurements among leukemic children. In contrast, the mean levels of all plasma proteins, especially PA (P < 0.005), were significantly lower in the D/R group than in the REM group. All D/R children, compared to 59% of those in remission, had PA levels < 20 mg/dl. Only the D/R group had abnormal levels of RBP, Tr, and Alb. Children who were treated with prednisone had significantly higher mean levels of PA, RBP, and AGP than those who were not receiving prednisone. The mean levels of acute phase-reactant proteins in these leukemic children were comparable to those of healthy children. We conclude that mild/moderate malnutrition is common in leukemic patients at D/R and that PA seems to be the most sensitive indicator of visceral protein status.

Transcriptional regulation of the Xenopus laevis B beta fibrinogen subunit gene by glucocorticoids and hepatocyte nuclear factor 1: analysis by transfection into primary liver cells

The blood-clotting protein fibrinogen is composed of three subunits, designated A alpha, B beta, and gamma, which are encoded by a family of related genes. As part of the acute-phase response, expression of the fibrinogen genes is coordinately regulated in the liver by glucocorticoids. To understand the factors underlying this hormonal response, we have examined control of transcription from fibrinogen gene fragments transfected into hepatocytes from the frog Xenopus laevis. This analysis is the first in any species to define transcriptional regulatory elements for the fibrinogen genes by transfection into primary liver cells, rather than liver-derived cell lines. A transfection vector was constructed containing the Xenopus B beta gene transcription start site and 1293 bp of the 5' flanking sequence linked to the firefly luciferase gene. When this construct was transfected into primary liver parenchymal cells, luciferase expression was induced approximately 14-fold by glucocorticoids, an increase similar to the transcriptional stimulation of the endogenous B beta subunit gene. DNA fragments with as little as 284 bases of upstream sequence retained full hormone responsiveness. This region contains a sequence resembling the canonical glucocorticoid response element (GRE) at bases -148 to -162. Deletions or specific point mutations eliminating this putative GRE led to complete loss of glucocorticoid inducibility. Physical association of the steroid hormone receptor with this functional GRE was demonstrated with a truncated form of the rat glucocorticoid receptor containing the DNA-binding domain. A second possible GRE at positions -526 to -540 was not hormone-responsive, in either the presence or the absence of the more proximal GRE. The regulatory region also has a sequence similar to the binding site for a liver-specific transcription factor, hepatocyte nuclear factor 1 (HNF-1), at positions -120 to -132. Specific point mutations in the HNF-1-binding site, in a construct containing a wild-type GRE, reduced promoter activity by a factor of 10, while stimulation by glucocorticoids was retained. Binding studies confirmed specific interaction between this site and the transcription factor HNF-1 alpha from mouse. Thus, we have identified a GRE sufficient to account for full glucocorticoid inducibility and an HNF-1 site close to the promoter that are major determinants of transcriptional control of the Xenopus fibrinogen B beta subunit gene in cells from normal liver tissue.

Cloning and tissue-specific expression of the gene for mouse C-reactive protein

C-reactive protein is a serum acute-phase reactant that increases several thousand-fold in concentration during inflammation in most mammals. However, mouse C-reactive protein is considered to be a minor acute-phase reactant, since its blood level increases only from approx. 0.1 to 1-2 micrograms/ml. A mouse genomic clone of approximately 5 kb was obtained to determine the molecular basis for the regulation of the expression of mouse C-reactive protein. Several cis-acting elements in the 5' flanking region that potentially regulate transcription were identified: two glucocorticoid-responsive elements, two CCAAT-enhancer-binding protein C (C/EBP) consensus elements that are required for the interleukin-1 responsiveness of some acute-phase reactant genes, an interleukin-6-responsive element, two hepatocyte nuclear factor-1 (HNF-1) elements and a single heat-shock element. Transfection of the hepatoma cell line Hep 3B.2 with a pCAT expression vector containing the 5' flanking sequence from -1083 to -3 bp from the transcriptional start site, and truncations of this sequence, localized elements that control the tissue-specific expression of mouse C-reactive protein to the two HNF-1 elements and a C/EBP, interleukin-1-responsive element located between -220 and -153, and -90 and -50 bp from the transcriptional start site. A constitutive nuclear protein from mouse-liver hepatocytes specifically binds to the HNF-1 elements. These findings explain the tissue-specific expression of the gene, as well as its limited expression during the acute-phase response.

Acute phase reactants and severity of homozygous sickle cell disease

Serum concentrations of seven acute-phase reactants: albumin, transferrin (Tf), alpha-1-antitrypsin (AIAT), caeruloplasmin (Cp), alpha 2-macroglobulin (alpha 2-MG), haptoglobin (hp) and C-reactive protein (CRP) were determined in 73 subjects with varying severities of homozygous sickle cell (HbSS) disease. Fifty healthy subjects of comparable sex, age and socio-economic class distributions as the HbSS subjects served as controls. Albumin and alpha 2-MG were comparable in all the subject groups. Tf and hp levels were significantly reduced in the HbSS groups relative to the control group. Conversely, AIAT, CRP and CP were significantly elevated. However only Tf and CRP manifested significant correlations with any of the indices of disease severity employed. Transferrin and CRP are suggested as plasma proteins worthy of further evaluation as indicators of severity in homozygous sickle cell disease.

Electrophoretic analysis of serum and urinary proteins in rats with aminonucleoside-induced nephrotic syndrome

Albumin; and alpha 1-, alpha 2-, beta-, and gamma-globulins were estimated by cellulose acetate electrophoresis in the serum and urine from rats with nephrotic syndrome (NS), 2, 4, 6, 8, 10, 12, 16, 20, and 30 days after a single injection of puromycin aminonucleoside (PAN). It was found that: (a) total serum protein level decreased on days 4-16, and total urine protein excretion rose on days 6-16; (b) serum albumin level fell on days 4-16, and urine albumin excretion increased on days 6-16; (c) serum alpha 1-globulin level rose on days 8-30, and urine alpha 1-globulin excretion increased on days 8-16; (d) serum alpha 2-globulin level remained essentially unchanged, and urine alpha 2-globulin excretion rose on days 4-10; (e) serum beta-globulin level decreased on days 4-20, and urine beta-globulin excretion increased on days 6-16, (f) serum gamma-globulin level diminished on days 6, 8, and 12, and urine gamma-globulin excretion rose on days 6-10. All serum protein fractions were excreted in the urine of nephrotic rats; these findings suggest that proteinuria is nonselective. The differences observed in the serum protein profiles, even when all protein fractions were lost in the urine, suggest an independent regulation of each protein fraction in PAN-nephrotic rats. In addition, the electrophoretic profile of serum proteins in PAN-nephrotic rats is different from previously reported patterns in human nephrosis and in rats with an acute-phase response.

Elevated levels of acute phase plasma proteins in major depression

Levels of acute phase and other plasma proteins were measured in 21 men with major depression, 28 men with alcohol dependence, and 12 men who acted as controls. The depressed men had significantly elevated levels of the acute phase proteins, haptoglobin and alpha-1-antichymotrypsin, and of immunoglobulin G. The elevations in haptoglobin and alpha-1-antichymotrypsin were highly correlated with each other, and were correlated with the severity of depression and negatively correlated with the thyroid stimulating hormone response to thyrotropin. The alcoholic men had elevated haptoglobin levels, but significantly decreased levels of immunoglobulin G. These findings provide further evidence for an inflammatory response during depression.

Measurement of T-kinin in rat plasma using a specific radioimmunoassay

T-kinin (Ile-Ser-Bradykinin) has been isolated only from the plasma of the rat and it is unclear whether the peptide, or its biosynthetic precursor, T-kininogen, circulates in the human. An NH2-terminally directed antiserum to T-kinin was raised in rabbits using an immunogen prepared by coupling the free -SH group of T-kinin extended from its COOH-terminus by a cysteinyl residue to an -NH2 group on human serum albumin. A radioimmunoassay was developed using this antiserum and 125I-labelled [Tyr10]T-kinin as tracer that was sensitive (least-detectable concentration 3 fmol/tube) and relatively specific for T-kinin (cross-reactivity with bradykinin and kallidin less than 1%). Treatment of rat plasma with an excess of trypsin in the presence of a kininase inhibitor generated T-kinin immunoreactivity equivalent to 455 +/- 71 pmol/ml (mean +/- S.E.M.; n = 9) and this immunoreactivity was eluted from a reversed-phase HPLC column as a single peak with the same retention time as synthetic T-kinin. In contrast, treatment of plasma from healthy human subjects (n = 8) and from patients (n = 8) with inflammation due to acute or chronic gastrointestinal disease under the same conditions did not generate any detectable T-kinin immunoreactivity. It is concluded, therefore, that T-kininogen, the biosynthetic precursor of T-kinin in the rat, is either absent from the plasma of human subjects or is present in a concentration less than 30 fmol/ml. Similarly, T-kininogen is probably not an acute phase reactant in humans.

Two-dimensional electrophoresis analysis of human serum proteins during the acute-phase response

The serum of patients with meningitis, due to infection by Haemophilus influenzae type b, was analyzed. Several known acute-phase proteins were separated by two-dimensional electrophoresis and estimated quantitatively. In addition, hitherto undescribed reactants were recognized. Gels were calibrated and relevant spots related to master spot numbers in the human serum protein database.

Individual regulation of different hepatocellular functions during sepsis

The purpose of this study was to test the hypothesis that different hepatocellular functions are regulated individually during sepsis. This was done by simultaneously measuring bile production, release of liver transaminases, and synthesis of secreted proteins in perfused livers from control and septic rats. Sepsis was induced by cecal ligation and puncture (CLP); control rats were sham-operated. After 16 hours, livers were perfused in situ, and bile flow, synthesis rates of albumin and alpha 1-acid glycoprotein (a major acute-phase protein in rats), and release of glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) into perfusate were determined. Within the same livers, sepsis resulted in a 54% increase in the synthesis of alpha 1-acid glycoprotein and approximately 30% inhibition of albumin synthesis concomitant with 50% lower bile flow. The concentrations of GOT and GPT in the perfusate increased slightly during the experiments, both when control and septic livers were perfused. The maintained tissue levels of adenosine triphosphate (ATP) and the uptake of Evans blue dye by less than 1% of the hepatocytes, although a late test of viability, suggest that both control and septic livers remained viable during perfusion. The results are consistent with the concept that different hepatocellular functions are individually regulated during sepsis. Thus, impairment of certain hepatocellular functions does not necessarily imply generalized liver failure.

Bovine haptoglobin: single radial immunodiffusion assay of its polymeric forms and dramatic rise in acute-phase sera

Using purified bovine haptoglobin (Hp) and specific antisera, a single radial immunodiffusion (SRID) assay method has been developed to measure the serum Hp level in cattle. Bovine Hp is a highly polymerized protein showing heterogeneous molecular forms in serum. After treatment with cysteine or glutathione, Hp was partially reduced to a homogeneous form, suitable for SRID assay. This method gives values comparable to those obtained by hemoglobin-binding capacity assay, and has the advantage of being simple and convenient. Although serum Hp was not detectable in healthy cattle, it was found more than 50-fold after invasive surgery, indicating that Hp is a characteristic acute-phase protein in cattle.

Inhibition of the oxidative burst response of N-formyl peptide-stimulated neutrophils by serum amyloid-A protein

Strong binding of the acute phase protein serum amyloid-A (SAA) to human neutrophils was found using flow cytometry. This binding was shown to be functionally relevant with respect to the oxidative burst reaction assayed on N-formyl peptide-stimulated neutrophils by the intracellular oxidation of non-fluorescent dihydrorhodamine to fluorescent rhodamine 123. The results show reduction of the oxidative burst response by isolated SAA (and recombinant SAA2). Inhibition was also demonstrated by acute phase as compared to normal human serum. This inhibitory effect was abolished by the purified monoclonal anti-amyloid A antibody mc29, strongly suggesting that SAA counteracts neutrophil responses to cytokines or bacterial products. This newly recognized function of SAA may help to prevent oxidative tissue destruction.

An immunochemical quantitative analysis of the protein pattern in physiologic and pathologic vitreous

Biochemical changes in the vitreous in different vitreoretinal disorders have not yet been thoroughly studied. Using enzyme-linked immunosorbent analysis (ELISA), we established mean values and 95% confidence intervals for six proteins of physiologic human vitreous: albumin (293 +/- 18 mg/l), transferrin (73.7 +/- 6.6 mg/l), immunoglobulin G (IgG), (33.5 +/- 3 mg/l), alpha 1-antitrypsin (14.1 +/- 2.9 mg/l), alpha 1-acid glycoprotein (4 +/- 0.7 mg/l), and lactoferrin (less than 50 micrograms/l). These six proteins were also determined in vitreous aspirates from patients with idiopathic proliferative vitreoretinopathy (n = 10), traumatic proliferative vitreoretinopathy (n = 10), and proliferative diabetic retinopathy (n = 15). The pattern of protein levels varied widely within each of the disorders. An analysis of absolute protein levels showed significant differences in total protein and alpha 1-antitrypsin levels between controls and pathologic vitreous samples. We observed differences in transferrin between controls and proliferative diabetic retinopathy (PDR), and differences in alpha 1-acid glycoprotein between controls and both types of proliferative vitreoretinopathy (PVR). The single disorders themselves could not be differentiated by any of the proteins. When the relative contribution of single proteins to total vitreal protein was compared, albumin was lower in all three disorders than in controls. Transferrin was lower in traumatic PVR than in controls, in PDR, or in idiopathic PVR. Our results indicate that the three vitreoretinal disorders studied are characterized by a breakdown of blood-ocular barriers.

Serum interleukin 6, C-reactive protein and pancreatic secretory trypsin inhibitor (PSTI) as acute phase reactants after major thoraco-abdominal surgery

We measured serum immunoreactive interleukin 6 (IL-6) levels in patients after major thoraco-abdominal surgery and compared them with changes in serum C-reactive protein (CRP) and pancreatic secretory trypsin inhibitor (PSTI) levels. Serum IL-6 levels were elevated earlier than serum CRP or PSTI. There were significant relationships between the peak levels of serum IL-6 and the operation time (p less than 0.05) or the volume of blood loss during surgery (p less than 0.05), showing that serum IL-6 can be a useful laboratory test for the evaluation of tissue injuries due to surgical intervention. Though there was a significant relationship between the peak levels of IL-6 and CRP (p less than 0.01), there was no relationship between the peak levels of IL-6 and PSTI.

Interleukin-6 and the acute phase response

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