Isolation of human C-reactive protein complementary DNA and localization of the gene to chromosome 1

Pentraxins in invertebrates and vertebrates: From structure, function and evolution to clinical applications

The immune system is divided into two broad categories, consisting of innate and adaptive immunity. As recognition and effector factors of innate immunity and regulators of adaptive immune responses, lectins are considered to be important defense chemicals against microbial pathogens, cell trafficking, immune regulation, and prevention of autoimmunity. Pentraxins, important members of animal lectins, play a significant role in protecting the body from pathogen infection and regulating inflammatory reactions. They can recognize and bind to a variety of ligands, including carbohydrates, lipids, proteins, nucleic acids and their complexes, and protect the host from pathogen invasion by activating the complement cascade and Fcγ receptor pathways. Based on the primary structure of the subunit, pentraxins are divided into short and long pentraxins. The short pentraxins are comprised of C-reactive protein (CRP) and serum amyloid P (SAP), and the most important member of the long pentraxins is pentraxin 3 (PTX3). The CRP and SAP exist in both vertebrates and invertebrates, while the PTX3 may be present only in vertebrates. The major ligands and functions of CRP, SAP and PTX3 and three activation pathways involved in the complement system are summarized in this review. Their different characteristics in various animals including humans, and their evolutionary trees are analyzed. The clinical applications of CRP, SAP and PTX3 in human are reviewed. Some questions that remain to be understood are also highlighted.

Early-Onset Neonatal Sepsis: Role of C-Reactive Protein, Micro-ESR, and Gastric Aspirate for Polymorphs as Screening Markers

INTRODUCTION

Early-onset neonatal sepsis is a major cause of morbidness and death in newborn children. Its timely diagnosis is usually a challenge in developing countries like India.

AIM

To study the efficacy of C-reactive protein (CRP), micro-ESR, and gastric aspirate for polymorphs in the diagnosis of early-onset neonatal sepsis.

MATERIALS AND METHODS

This study included sixty term and preterm children, inborn and referred cases. The children who presented before day seven of life with clinical suspicion of sepsis or who were at high risk of developing sepsis were included. These were further investigated. Significant values for screening tests were taken as C - reactive protein > 0.6 mg/dl, micro-ESR-after 1 hour, fall in the column of blood in capillary tube was measured, and result was taken as mm fall in 1 hr, and gastric aspirate for polymorphs > 5 polymorphs/HPF. Sepsis screen positive result was 2 or more positive tests. The statistical evaluation was done using Fisher, and ANOVA tests using SPSS 20.0 version.

RESULTS

Sixty children were included in the study with forty as the referred ones. Most of them had tachypnea (45%). CRP showed high sensitivity, whereas micro-ESR and gastric aspirate for polymorphs showed high specificity.

CONCLUSIONS

Neonatal sepsis screening is required for the detection of infection as the blood culture report may not be positive in all the cases, and even if positive, the result takes few hours. CRP showed high sensitivity, whereas micro-ESR and gastric aspirate for polymorphs showed high specificity independently as well as when combined.

Neuronal pentraxins as biomarkers of synaptic activity: from physiological functions to pathological changes in neurodegeneration

The diagnosis of neurodegenerative disorders is often challenging due to the lack of diagnostic tools, comorbidities and shared pathological manifestations. Synaptic dysfunction is an early pathological event in many neurodegenerative disorders, but the underpinning mechanisms are still poorly characterised. Reliable quantification of synaptic damage is crucial to understand the pathophysiology of neurodegeneration, to track disease status and to obtain prognostic information. Neuronal pentraxins (NPTXs) are extracellular scaffolding proteins emerging as potential biomarkers of synaptic dysfunction in neurodegeneration. They are a family of proteins involved in homeostatic synaptic plasticity by recruiting post-synaptic receptors into synapses. Recent research investigates the dynamic changes of NPTXs in the cerebrospinal fluid (CSF) as an expression of synaptic damage, possibly related to cognitive impairment. In this review, we summarise the available data on NPTXs structure and expression patterns as well as on their contribution in synaptic function and plasticity and other less well-characterised roles. Moreover, we propose a mechanism for their involvement in synaptic damage and neurodegeneration and assess their potential as CSF biomarkers for neurodegenerative diseases.

Therapeutic Lowering of C-Reactive Protein

In the blood of healthy individuals C-reactive protein (CRP) is typically quite scarce, whereas its blood concentration can rise robustly and rapidly in response to tissue damage and inflammation associated with trauma and infectious and non-infectious diseases. Consequently, CRP plasma or serum levels are routinely monitored in inpatients to gauge the severity of their initial illness and injury and their subsequent response to therapy and return to health. Its clinical utility as a faithful barometer of inflammation notwithstanding, it is often wrongly concluded that the biological actions of CRP (whatever they may be) are manifested only when blood CRP is elevated. In fact over the last decades, studies done in humans and animals (e.g. human CRP transgenic and CRP knockout mice) have shown that CRP is an important mediator of biological activities even in the absence of significant blood elevation, i.e. even at baseline levels. In this review we briefly recap the history of CRP, including a description of its discovery, early clinical use, and biosynthesis at baseline and during the acute phase response. Next we overview evidence that we and others have generated using animal models of arthritis, neointimal hyperplasia, and acute kidney injury that baseline CRP exerts important biological effects. In closing we discuss the possibility that therapeutic lowering of baseline CRP might be a useful way to treat certain diseases, including cancer.

Acute phase reactants as novel predictors of cardiovascular disease

Acute phase reaction is a systemic response which usually follows a physiological condition that takes place in the beginning of an inflammatory process. This physiological change usually lasts 1-2 days. However, the systemic acute phase response usually lasts longer. The aim of this systemic response is to restore homeostasis. These events are accompanied by upregulation of some proteins (positive acute phase reactants) and downregulation of others (negative acute phase reactants) during inflammatory reactions. Cardiovascular diseases are accompanied by the elevation of several positive acute phase reactants such as C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, white blood cell count, secretory nonpancreatic phospholipase 2-II (sPLA2-II), ferritin, and ceruloplasmin. Cardiovascular disease is also accompanied by the reduction of negative acute phase reactants such as albumin, transferrin, transthyretin, retinol-binding protein, antithrombin, and transcortin. In this paper, we will be discussing the biological activity and diagnostic and prognostic values of acute phase reactants with cardiovascular importance. The potential therapeutic targets of these reactants will be also discussed.

C-reactive protein (CRP) elevation in patients with abdominal aortic aneurysm is independent of the most important CRP genetic polymorphism

OBJECTIVE

C-reactive protein (CRP) is a marker of cardiovascular disease. The objective was to determine if abdominal aortic aneurysm (AAA) and CRP serum concentration and its CRP gene are associated.

METHODS AND RESULTS

AAA patients and AAA negative controls were recruited. CRP concentration was measured and the single nucleotide polymorphism (SNP), rs3091244, assessed. AAA cases were divided into those measuring 30-55 mm and >55 mm in diameter, to assess correlation of CRP with AAA size. A total of 248 (227 male) cases and 400 (388 male) controls were included. CRP concentration was higher in cases (385.0 microl/dL [310.4-442.8] vs 180.3 microl/dL [168.1-196.9]; P < .0001). It was higher in large aneurysms (685.7 microl/dL [511.8-1083.0] vs 291.0 microl/dL [223.6-349.6]; P < .0001), with significant correlation observed to size (r = 0.37, P < .0001). CC was the most common SNP genotype with no difference in distribution (P = .43) between cases and controls. No difference existed in CRP for each genotype in the overall cohort (P = .17), cases (P = .18) and controls (P = .19).

CONCLUSION

The results demonstrate that CRP production may be related to the presence of AAA, especially in advanced disease. The serum concentration of CRP does not appear to be influenced by the functional SNP of the CRP gene, which also appears to have no association with AAA formation.

C-Reactive Protein Gene Polymorphisms, C-Reactive Protein Blood Levels, and Cardiovascular Disease Risk

C-reactive protein (CRP), a blood marker of inflammation and a hallmark of the acute-phase response, has been shown to be a powerful and specific predictor of cardiovascular event risk in populations of otherwise healthy persons. Here we review what is known about CRP gene polymorphisms, discuss how these might affect the epidemiology of CRP and our understanding of CRP's contribution to cardiovascular disease, and examine their potential clinical usefulness. Evidence shows that certain subtle variations in the CRP gene sequence, mostly single nucleotide polymorphisms, predictably and strongly influence the blood level of CRP. Some of these variations are associated with clinical correlates of cardiovascular disease. If future studies can establish with certainty that CRP influences cardiovascular biology, then CRP gene profiling could have clinical utility.

The relationship between gene polymorphism and CRP level in a Chinese Han population

We investigated the relationships among the +1444C/T polymorphism in the C-reactive protein (CRP) gene and the concentration of CRP and the risk of coronary heart disease. Using polymerase chain reaction-restriction fragment length polymorphism, we analyzed the frequency distribution of genotypes and alleles of the +1444C/T polymorphism in samples from 128 patients with coronary heart disease (coronary stenosis more than 50%) and 119 unrelated normal individuals. The plasma levels of CRP and lipids in the subjects were also measured. The frequencies of the genotypes were CC 89.1%, CT 10.9%, and TT 0% in patients and CC 89.9%, CT 10.1%, and TT 0% in controls. The frequency of allele C was 94.5% in patients and 95.0% in controls, and allele T was 5.5% in patients and 5.1% in controls. The distribution of genotypes and alleles in the Chinese Han population was significantly different from that of the Caucasian population. There were no significant differences between frequencies of genotype and allele of controls and those of patients (P>0.05), but in controls the concentrations of CRP in the CC genotype subgroup were significantly higher than those in the CT genotype subgroup (P<0.05). This suggests that the +1444C/T variant in the CRP gene influences the basal CRP level in normal people. These findings imply that there may eventually be a need to establish genotype-specific risk thresholds of the CRP level.

Diagnostic value of C-reactive protein for predicting activity level of Crohn's disease

BACKGROUND AND AIMS

Measuring Crohn's disease (CD) activity is useful in clinical trials as well as in clinical practice, but each available instrument to measure such activity has some limitations. C-reactive protein (CRP) is a sensitive marker for inflammation and tissue injury. The aims of the study were: to assess the diagnostic value of low level of CRP for predicting a low CD activity, and to calculate optimal CRP cutoff value for selecting patients with moderate or high CD activity.

METHODS

One hundred fifty consecutive patients with active or nonactive CD were included in the study without any pre-selection criteria. CRP was measured, and CD activity was calculated by means of the van Hees index (VHI).

RESULTS

The median VHI score was 154.4 (interquartile range, 126.0-193.4), and the median CRP was 19.1 mg/L (interquartile range, 6.1-50.1 mg/L; upper limit of normal [N], 4 mg/L). Forty-nine percent of our patients had CRP >20 mg/L. CRP was significantly correlated to VHI (P = .0001). The probability that VHI was <150 if CRP was below upper limit of normal was equal to 1 (confidence interval, 0.891-1.000). The diagnostic value for CRP predicting a VHI > or =150 was high; the area under the receiver operating characteristic curve was equal to 0.844 (confidence interval, 0.783-0.906; P = .0001) with an optimal cutoff value of 21.6 mg/L, about 5 x N.

CONCLUSIONS

CRP appears useful to evaluate CD activity, especially to predict inactive or low activity CD.

Linking C-reactive protein to late-life disability in the National Health and Nutrition Examination Survey (NHANES) 1999-2002

BACKGROUND

Chronic inflammation, measured by interleukin-6, predicts incident disability among elderly people. However, little is known about the relation of C-reactive protein (CRP) to disability.

METHOD

Participants (>60 years old, N = 1680) were from the National Health and Nutrition Examination Survey 1999-2002. Disability in activities of daily living (ADL), instrumental activities of daily living (IADL), leisure and social activities (LSA), lower extremity mobility (LEM), and general physical activities (GPA) was obtained by self-report. Peak muscle power was the product of isokinetic peak leg torque and peak force velocity. Functional limitations were evaluated via habitual walking speed, which was obtained from a 20-foot timed walk. CRP levels were quantified by using latex-enhanced nephelometry.

RESULTS

Elevated CRP levels were associated with disability in IADL, LSA, LEM, and GPA, independent of basic demographics, chronic medical diseases, health behaviors, as well as nutritional markers. The corresponding odds ratios of disability for each standard-deviation increase in natural-log-transformed CRP were 1.18 (95% confidence interval [CI], 1.02-1.35), 1.18 (95% CI, 1.00-1.39), 1.17 (95% CI, 1.03-1.33), and 1.17 (95% CI, 1.05-1.31), respectively. The relationship diminished after additional adjustment of leg power and/or walking speed, meaning that impairment in leg power and limitations in gait speed likely mediate the association between CRP and disability. CRP had an inverse relationship to leg power and walking speed. Likewise, additional adjustment for leg power substantially diminished the association between CRP and walking speed, suggesting a mediating effect of power between CRP and gait speed.

CONCLUSIONS

Independent of chronic diseases, elevated CRP is associated with multiple domains of disability through mediation of muscle power, habitual gait speed, or both. Future research is needed to understand CRP as a risk factor for disability in older populations.

C-Reactive Protein: A Family of Proteins to Regulate Cardiovascular Function

Based on a multitude of clinical studies, C-reactive protein (CRP) has emerged as a risk marker for the development of cardiovascular disease, leading to recently published recommendations for screening the general population for plasma CRP level as a predictor for future cardiovascular events. However, uncertainties exist in how to apply these recommendations to populations with very high serum CRP levels and a high prevalence of cardiovascular disease, such as patients with end-stage renal disease. Furthermore, in vitro results are conflicting concerning the role of CRP in the vessel wall. Although many data are in favor of a proinflammatory effect of CRP, evidence is accumulating that CRP also exerts anti-inflammatory actions, mainly in neutrophils and platelets. Many of the apparently contradictory actions of CRP may be attributed to method issues, but, of interest, also may be explained by the existence of 2 distinct conformations of CRP, the native pentamer (nCRP) and modified CRP (mCRP) forms. nCRP is the classical acute-phase reactant detected in serum, whereas mCRP represents a predominantly tissue-bound form. It is detected immunohistochemically, mainly in and around endothelial and vascular smooth muscle cells. Although mCRP activates endothelial cells and neutrophils, induces neutrophil adhesion to the endothelium, and delays apoptosis of neutrophils in vitro, these effects were absent using nCRP. Clearly defined CRP conformers thus may provide a tool for how to reconcile the reported proinflammatory and anti-inflammatory properties of CRP. There is good evidence to believe that CRP is more than just a "bad guy," and further experiments are needed to determine how these 2 configurations contribute to atherogenesis, development of cardiovascular disease, and acute coronary events.

Serum amyloid P-component in murine tuberculosis: induction kinetics and intramacrophage Mycobacterium tuberculosis growth inhibition in vitro

Serum amyloid P-component (SAP), a pentraxin, is known to play an important role in innate immunity to microbial infections; however, nothing is known about it during tuberculosis (TB). Mice intratracheally infected with Mycobacterium tuberculosis Erdman, showed peak SAP levels (442+/-58.2 microg/ml) on day 21, which declined to background levels by day 60. Their serum interleukin-6 levels paralleled SAP levels, whereas, their serum transforming growth factor-beta levels were paradoxical. During the acute phase of infection, the SAP levels positively correlated with the lung mycobacterial load. Purified mouse SAP (1-50 microg/ml) treatment of M. tuberculosis-infected alveolar macrophages (AMs), in vitro, inhibited their intracellular mycobacterial growth; maximum inhibition (1.1 log10 CFU reduction) occurred at 10 microg/ml, and a 4-day treatment appeared optimal. Treatment of AMs with both rabbit anti-mouse SAP polyclonal antibody and mannose-derived simple sugars, separately, blocked the SAP-induced inhibition of mycobacterial growth. The mycobacterial growth inhibition appeared to be nitric oxide (NO)-dependent as NO synthase inhibitors, both aminoguanidine and N(G)-monomethyl-L-arginine, annulled it. Further, SAP treatment of infected AMs induced significant (P<0.05) elaboration of nitrite (72.1+/-8.3 nM/ml), compared to the controls, and these AMs showed augmented expression of inducible NO synthase. This first study demonstrates that during murine TB the SAP levels were increased, and purified mouse SAP inhibited the intra-AM M. tuberculosis growth, in vitro, apparently via NO-dependent mechanism(s). SAP may thus contribute both to the pathogenesis and pulmonary innate immunity in TB.

C-reactive protein as a marker for inflammatory bowel disease

The production of CRP occurs almost exclusively in the liver by the hepatocytes as part of the acute phase response upon stimulation by IL-6, TNF-alphaand IL-1-betaoriginating at the site of inflammation. Its short half-life makes CRP a valuable marker to detect and follow up disease activity in Crohn's disease (CD). In contrast, ulcerative colitis has only a modest to absent CRP response despite active inflammation, and the reason for this is unknown. In CD, serum levels of CRP correlate well with disease activity and with other markers of inflammation as the CDAI, serum amyloid, IL-6 and faecal calprotectin. CRP is a valuable marker for predicting the outcome of certain diseases as coronary heart disease and haematological malignancies. An increased CRP (>45 mg/L) in patients with IBD predicts with a high certainty the need for colectomy and this by reflecting severe ongoing and uncontrollable inflammation in the gut. Finally, trials with anti-TNF and anti-adhesion molecules have shown that a high CRP predicts better response to these drugs. However, whether we need to include CRP as an inclusion criterion for future trials with biologicals is still a matter of debate.

C-reactive protein and cardiovascular disease: new insights from an old molecule

The classical acute-phase protein, C-reactive protein (CRP), is an exquisitely sensitive systemic marker of disease with broad clinical utility for monitoring and differential diagnosis. Inflammation, the key regulator of CRP synthesis, plays a pivotal role in atherothrombotic cardiovascular disease. There is a powerful predictive association between raised serum CRP values and the outcome of acute coronary syndromes, and, remarkably, between even modestly increased CRP production and future atherothrombotic events in otherwise healthy individuals. Baseline CRP values also reflect metabolic states associated with atherothrombotic events. The presence of CRP within most atherosclerotic plaques and all acute myocardial infarction lesions, coupled with binding of CRP to lipoproteins and its capacity for pro-inflammatory complement activation, suggests that CRP may contribute to the pathogenesis and complications of cardiovascular disease. We review the biological properties of CRP, the association between CRP and cardiovascular disease, and the possibility that CRP may be a novel therapeutic target.

High sensitivity C-reactive protein: an emerging role in cardiovascular risk assessment

Coronary heart disease (CHD) is the major cause of death in the developed world and screening for conventional cardiovascular risk factors fails to identify more than 50% of the individuals who will present with acute coronary syndromes. Chronic inflammation appears to play a significant role in the initiation and development of atherosclerosis. Recent investigations have shown an association between inflammatory markers such as C-reactive protein (CRP) and CHD. These markers have proven useful as prognostic indicators in acute coronary syndromes and in predicting future coronary events in apparently healthy men and women. The availability of high sensitivity CRP (hs-CRP) assays has been crucial in exploring the role of this acute phase reactant in primary prevention settings. In this review, we discuss the evidence associating these inflammatory markers, especially CRP, with the pathogenesis of atherosclerosis and acute coronary syndromes, and we address the mechanism of risk as well as the clinical utility of this marker.

C-reactive protein as a predictor of improvement and readmission in heart failure

OBJECTIVES

Only recently, new risk factors to explain atherosclerotic disease have been identified. One of the most important clinical manifestations of atherosclerosis is heart failure. Our study was aimed at investigating C-reactive protein (CRP), a marker of systemic inflammation, in the context of heart failure, and to determine its usefulness in predicting the need for readmission in patients with heart failure and their degree of improvement.

DESIGN

We studied patients admitted to our hospital due to heart failure, independent of the cause. CRP levels were measured with a sensitive standard assay on a Nephelometer analyser. Patients were classified on admission and discharge following New York Heart Association (NYHA) functional criteria; left ejection fraction was also determined by transthoracic echocardiography. Patients presenting clear sources of infection or inflammatory disease were excluded. Our control group consisted of patients admitted for syncope. Each patient was followed up through a computer system controlling admissions to and discharge from the hospital, for a period of 18 months after initial admission. End points considered were NYHA functional class on discharge, readmission and death.

RESULTS

We studied prospectively 76 patients with a mean age of 73.5+/-11 [95% confidence interval (CI) 71.2-75.8]; 44 were male (58%) and 32 female (42%). The mean CRP level in patients with heart failure was 3.94+/-5.87 (95% CI, 1.26-7.60), while in 15 patients with syncope it was 0.84+/-1.95 (95% CI, 0.96-2.94) (P=0.0007). The principal causes of heart failure included dilated cardiomyopathy due to coronary arterial disease (30%), valvular disease (28%) and heart failure secondary to hypertension (25%). The mean left ejection fraction adequately measured in 72 (95%) patients was 50.41+/-9.88 (95% CI, 41.20-59.65). We observed a trend of higher CRP levels in relation to ejection fractions below 35%: 7.50+/-9.88 vs. 3.75+/-4.57, (P=0.09). Our results showed that on discharge CRP levels increased in relation to NYHA class: I: 0.74+/-0.69; II: 3.78+/-3.76; III: 7.4+/-8.65; IV: 12.2+/-15.27 (P<0.05). On follow-up of each patient for 18 months, 32 (43%) were readmitted due to deterioration of their heart condition. For patients who were readmitted, those presenting CRP levels >0.9 mg/dl were identified as candidates for earlier hospitalisation than those with levels below 0.9 mg/dl (P=0.02) RR=1.43. In logistic-regression analysis the only group of tested variables predicting readmission were levels of CRP, NYHA class and plasmatic K on discharge and left ventricle ejection fraction. Analysis of covariates yields CRP levels as being an independent predictor of readmission.

CONCLUSIONS

An inflammatory response is present in deteriorating heart failure. We observed higher CRP levels in patients with higher NYHA functional class, perhaps signalling a poor therapeutic response. Higher CRP levels were also related to higher rates of readmission and mortality and it could be an independent marker of improvement and readmission in heart failure.

Hepatocellular expression of a dominant-negative mutant TGF-beta type II receptor accelerates chemically induced hepatocarcinogenesis

The potent growth-inhibitory activity of cytokines of the transforming growth factor-beta (TGF-beta) superfamily and their widespread expression in epithelia suggest that they may play an important role in the maintenance of epithelial homeostasis. To analyse TGF-beta mediated tumor suppressor activity in the liver, we generated transgenic mice overexpressing a dominant negative type II TGF-beta receptor in hepatocytes under control of the regulatory elements of the human C-reactive protein gene promoter. Transgenic animals exhibited constitutive and liver-specific transgene expression. The functional inactivation of the TGF-beta signaling pathway in transgenic hepatocytes was shown by reduced TGF-beta induced inhibition of DNA synthesis in primary hepatocyte cultures. Liver morphology and spontaneous tumorigenesis were unchanged in transgenic mice suggesting that interruption of the signaling of all three isoforms of TGF-beta in hepatocytes does not disturb tissue homeostasis in the liver under physiological conditions. However, following initiation with the carcinogen diethylnitrosamine and tumor-promotion with phenobarbital transgenic mice exhibited a moderate albeit significant increase in the incidence, size and multiplicity of both preneoplastic tissue lesions in the liver and of hepatocellular carcinomas. These results give in vivo evidence for a tumor suppressor activity of the endogenous TGF-beta system in the liver during chemical hepatocarcinogenesis.

High-sensitivity C-reactive protein and atherosclerosis: from theory to therapy

Atherosclerosis remains the leading cause of morbidity and mortality in Western countries. Recent evidence has demonstrated that atherosclerosis is not simply a disease of lipid deposition. Inflammation plays a major role in the initiation, progression, and destabilization of atheromas. High-sensitivity C-reactive protein (hs-CRP) is a circulating acute-phase reactant that reflects active systemic inflammation. Large prospective trials have shown hs-CRP to be a strong predictor of future cardiovascular events. Increased hs-CRP concentration is in fact associated with higher cardiovascular events in individuals with and without clinical evidence of atherosclerotic disease. The relative risk associated with hs-CRP is independent of other cardiovascular disease risk factors. Assays for hs-CRP measurement are currently available but must be standardized because patients' results will be interpreted by using population-based cutpoints. A risk-stratifying algorithm incorporating hs-CRP and total cholesterol to high-density lipoprotein cholesterol ratio has been proposed. Further research into the mechanisms and pharmacological treatment of vascular disease will provide novel management strategies in the very near future.

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.

TGF-beta1 in liver fibrosis: an inducible transgenic mouse model to study liver fibrogenesis

Transforming growth factor-beta1 (TGF-beta1) is a powerful stimulus for collagen formation in vitro. To determine the in vivo effects of TGF-beta1 on liver fibrogenesis, we generated transgenic mice overexpressing a fusion gene [C-reactive protein (CRP)/TGF-beta1] consisting of the cDNA coding for an activated form of TGF-beta1 under the control of the regulatory elements of the inducible human CRP gene promoter. Two transgenic lines were generated with liver-specific overexpression of mature TGF-beta1. After induction of the acute phase response (15 h) with lipopolysaccharide (100 microgram ip), plasma TGF-beta1 levels reached >600 ng/ml in transgenic animals, which is >100 times above normal plasma levels. Basal plasma levels of uninduced transgenic animals were about two to five times above normal. As a consequence of hepatic TGF-beta1 expression, we could demonstrate marked transient upregulation of procollagen I and procollagen III mRNA in the liver 15 h after the peak of TGF-beta1 expression. Liver histology after repeated induction of transgene expression showed an activation of hepatic stellate cells in both transgenic lines. The fibrotic process was characterized by perisinusoidal deposition of collagen in a linear pattern. This transgenic mouse model gives in vivo evidence for the important role of TGF-beta1 in stellate cell activation and liver fibrogenesis. Due to the ability to control the level of TGF-beta1 expression, this model allows the study of the regulation and kinetics of collagen synthesis and fibrolysis as well as the degree of reversibility of liver fibrosis. The CRP/TGF-beta1 transgenic mouse model may finally serve as a model for the testing of antifibrogenic agents.

Comparison of sequence of cDNA clone with other genomic and cDNA sequences for human C-reactive protein

A clone for C-reactive protein (CRP) has been isolated from a human liver cDNA library; this clone harbors a plasmid, pC81, which has an insert of 1631 bp. When compared to genomic and cDNA sequences published to date now, pC81 has revealed homologies and differences that might help to clarify the structure of this gene and the presence of allelic variants in man.

Properties of four acute phase proteins: C-reactive protein, serum amyloid A protein, alpha 1-acid glycoprotein, and fibrinogen

Four plasma proteins, referred to as positive acute phase proteins because of increases in concentration following inflammatory stimuli, are reviewed: C-reactive protein (CRP), serum amyloid A protein (SAA), alpha 1-acid glycoprotein (AAG), and fibrinogen. The CRP and SAA may increase in concentration as much as 1000-fold, the AAG and fibrinogen approximately twofold to fourfold. All are synthesized mainly in the liver, but each may be produced in a number of extrahepatic sites. The role of cytokines in induction of the acute phase proteins is discussed, particularly the multiple functional capabilities of interleukin-6 (IL-6). Other cytokines that regulate acute phase gene expression and protein synthesis include IL-1, tumor necrosis factor alpha, interferon gamma, as well as other stimulatory factors and cofactors. The physicochemical characteristics of each protein are reviewed together with the molecular biology. For each protein, the known biological effects are detailed. The following functions for CRP have been described: reaction with cell surface receptors resulting in opsonization, enhanced phagocytosis, and passive protection; activation of the classical complement pathway; scavenger for chromatin fragments; inhibition of growth and/or metastases of tumor cells; modulation of polymorphonuclear function; and a few additional diverse activities. The role of plasma SAA is described as a precursor of protein AA in secondary amyloidosis; other functions are speculative. AAG may play an immunoregulatory role as well as a role in binding a number of diverse drugs. In addition to clot formation, new data are described for binding of fibrinogen and fibrin to complement receptor type 3. Finally, the concentration of each protein is discussed in a wide variety of noninfectious and infectious disease states, particularly in connective tissue diseases. The quantification of the proteins during the course of various acute and chronic inflammatory disorders is useful in diagnosis, therapy, and in some cases, prognosis.

The biochemical genetics of amyloid fibril proteins

Amyloidoses are a very heterogeneous set of diseases, characterized by extracellular deposition of fibrillar proteins in different tissues. It is still a matter of debate whether the different forms of amyloidosis can share some common etiological mechanisms, or they are completely unrelated. The biochemical characterization of the protein component of the deposits provides a powerful system of classification for the different amyloidotic disorders and shades light on the molecular mechanisms of selective precipitation from soluble precursors and of tissue-specific deposition. Furthermore, identification and analysis of the genes coding for the precursors, and clarification of the kind of inheritance in some familial forms of amyloidosis, make prevention through genetic counselling and predictive diagnosis possible.

Liver-specific and high-level expression of human serum amyloid P component gene in transgenic mice

To analyze the regulation of human serum amyloid P component (SAP) gene expression, we have produced seven transgenic mice. The 3.3 kb human SAP genes containing about 0.8 kb of 5' and 1.5 kb of 3' flanking region were injected into fertilized eggs of C57BL/6 mice. In five of the seven transgenic mice, human SAP was detected in the sera and serum concentrations were higher than that of human serum in three lines. The human SAP gene was expressed only in the liver. Amounts of human mRNA in the liver and serum concentrations of human SAP were roughly proportional to the copy number of the integrated gene. Human SAP production lowered the serum levels of mouse endogenous SAP. With the intraperitoneal administration of lipopolysaccharide, the mRNA levels in the liver and serum levels of mouse SAP increased several-fold in both the control and transgenic mice. On the other hand, neither the mRNA nor the serum levels of human SAP increased significantly.

Structure of the mouse C-reactive protein gene

A genomic DNA clone corresponding to the mouse C-reactive protein (CRP) has been isolated and characterized. The mouse CRP gene is 1.9-kilobase pairs in length and contains a single intron of 213-base pairs which interrupts the codon for the 2nd amino acid residue of the mature CRP protein. We compared nucleotide sequences of the mouse and human CRP genes and discussed structures of possible regulatory sequences. With this characterization, the isolation and sequence analyses of a set of mouse and human pentraxin genes, i.e. CRP and serum amyloid P component genes is not complete.

Stimulation of human neutrophils, monocytes, and platelets by modified C-reactive protein (CRP) expressing a neoantigenic specificity

C-reactive protein (CRP) can be structurally modified by heat, acid, or urea-chelation to express a neoantigen designated by us as neo-CRP. This antigen is also expressed on the in vitro primary protein translation products of both human and rabbit CRP. Unmodified CRP and CRP complexed with pneumococcal C-polysaccharide (CPS) do not express neo-CRP. Forms of CRP expressing neo-CRP but not native CRP antigenicity (even in the presence of CPS) consistently and in a dose-dependent manner potentiated the respiratory burst response of human polymorphonuclear leukocytes and peripheral blood monocytes to heat-modified IgG. Forms of CRP expressing neo-CRP antigenicity also induced reactions of aggregation and secretion from isolated platelets and potentiated platelet activation stimulated by ADP in platelet-rich-plasma, while native CRP alone or complexed with CPS again did not. Unlike CRP-CPS complexes, forms of CRP expressing neo-CRP were not able to activate the complement system. These data emphasize the biologic potential inherent in this humoral acute-phase reactant, particularly in the activation of the formed elements of the blood important in the inflammatory response. Since these cell-activating properties are preferentially observed when CRP is structurally modified to express the neo-CRP antigen, such a molecular conversion may be central to the structure-function relationships of CRP at local sites of inflammation and tissue injury.

Identification of sequences responsible for acute-phase induction of human C-reactive protein

Human C-Reactive protein (CRP) is inducible in liver cells during acute inflammation. Around 90 bp from the 5' flanking region of the human CRP gene contain, as shown here, information to induce the expression of a linked bacterial CAT gene specifically in human hepatoma (Hep3B) cells. The promoter is induced rapidly, faithfully and at high efficiency when transfected cells are exposed to conditioned medium from lipopolysaccharide stimulated peripheral monocytes. The sequences required for inducibility are located immediately upstream to the TATA element. A DNA segment from base -121 to -50 is capable of inducing transcription from the heterologous SV40 early promoter. Induction of CRP expression is probably exerted via the binding of at least one positive trans-acting factor.

Monocyte-conditioned medium, interleukin-1, and tumor necrosis factor stimulate the acute phase response in human hepatoma cells in vitro

Human hepatoma cells mimic the acute phase response after treatment with monocyte-conditioned medium. Levels of secreted fibrinogen, alpha-1 acid glycoprotein, C-reactive protein, haptoglobin, and the third component of complement were elevated compared with control levels after 48 h of incubation with conditioned supernatant medium from an enriched fraction of normal peripheral monocytes. Albumin levels declined and alpha-1 antitrypsin remained unchanged. Levels of specific mRNA were measured by hybridization to slot blots and Northern blots and changed in correspondence with protein alterations. Interleukin-1 and tumor necrosis factor stimulated the third component of complement, but did not elevate any other member of the acute phase group and were therefore only partially active in this system. The identification of an in vitro model of the human acute phase response will permit analysis of the molecular basis for coordinate regulation of this group of facultative genes.

Expression of murine 21-hydroxylase in mouse adrenal glands and in transfected Y1 adrenocortical tumor cells

The S region of the murine major histocompatibility complex contains two structurally related genes (21-OHase A and 21-OHase B) that encode 21-hydroxylase (21-OHase), an enzyme essential for the synthesis of adrenal steroids. Expression of these two genes has been analyzed by using oligonucleotide probes specific for the 21-OHase A and B genes and by DNA-mediated gene transfer. Hybridization of the oligonucleotides to blots of BALB/c adrenal RNA demonstrated that all 21-OHase mRNA is derived from the 21-OHase A gene. Cosmids bearing either the 21-OHase A or B gene were introduced into Y1 adrenocortical tumor cells by cotransfection with pSV2-neo. Cells transfected with the 21-OHase A gene expressed 21-OHase as determined by steroid metabolism and by RNA blot hybridization; 21-OHase transcripts were not detected in parent Y1 cells or in cells transfected with the 21-OHase B gene. Treatment of 21-OHase A transfectants with adrenocorticotropin increased 21-OHase mRNA levels by up to 10-fold, thus mimicking the observed effect of this hormone on 21-OHase levels in primary adrenal cultures. The regulated expression of the 21-OHase A gene in transfected Y1 cells should provide a useful system for the investigation of factors controlling the adrenal-specific regulation of 21-OHase activity.

Mouse serum amyloid P-component (SAP) levels controlled by a locus on chromosome 1

Recombinant inbred strains were used to demonstrate the existence of a major locus on chromosome 1, designated Sap, which controls the endogenous concentration of the mouse acute phase reactant, serum amyloid P-component (SAP). Levels of SAP were associated with alleles at the Ly-9 locus in two sets of RI strains: BXD (C57BL/6J X DBA/2) and BXH (C57BL/6J X C3H/HeJ). Low endogenous levels of SAP were present in the C57BL/6J progenitor strain and in most of the RI strains which inherited the Ly-9b allele. High levels of SAP were present in the DBA/2J and C3H/HeJ progenitors and in most of the RI strains which inherited the Ly-9a allele. In the BXD strains 91% of the genetic variation of SAP levels was accounted for by segregation at the Ly-9 locus while an additional 9% was attributed to genetic factors unlinked to Ly-9. In the BXH strains the percentage of genetic variation accounted for by Ly-9 segregation was reduced to 46%, while 54% was accounted for by other genetic factors. Because of background genetic variation it was not possible to detect any crossovers between Sap and Ly-9. However, in the BXD strains the linkage between Sap and Ly-9 appears to be quite close. The B6.C-H-25c congenic strain, which carries a segment of BALB/c chromosome 1 including the minor histocompatibility locus H-25 on a C57BL/6By background, had the same endogenous SAP level as the BALB/c donor strain.