Homologs of CRP: a diverse family of proteins with similar structure

Rat C-reactive protein causes a charge modification of LDL and stimulates its degradation by macrophages

We have previously shown the binding of low-density lipoprotein (LDL) to immobilized rat C-reactive protein (CRP) and the formation of a fluid-phase complex between these two proteins. In this report we used immunoelectrophoresis and agarose gel electrophoresis to show increased anodic migration of the LDL particle as a result of the modification of LDL by rat CRP. The degradation of the modified 125I-LDL by rat peritoneal macrophages was increased more than twofold in the presence of rat CRP. The increase in rat CRP-mediated 125I-LDL degradation by macrophages was dependent on the concentrations of 125I-LDL and rat CRP. This increased 125I-LDL degradation was inhibited by phosphorylcholine. In contrast, the degradation of 125I-acetyl-LDL by macrophages was not affected by rat CRP, although acetylated LDL inhibited the rat CRP-stimulated degradation of 125I-LDL. Increasing concentrations of LDL did not affect the degradation of rat 125I-CRP by the macrophages, which suggested that the rat CRP and the modified LDL did not enter the cell as a complex. Our results suggested that the increased degradation of 125I-LDL was caused by the charge modification of 125I-LDL by rat CRP, due to a fluid-phase complex formation between 125I-LDL and rat CRP, and that the degradation involved the scavenger receptor present on the macrophages.

C-reactive protein--a characteristic feature of health control in swine

In this study 120 weaned female piglets were clinically examined and porcine C-reactive protein (CRP) concentration determined in blood serum by means of a competitive enzyme ligand assay. CRP values were put into relation to clinical (catarrh, diarrhoea, inflammation and fever) and pathomorphological findings. It was found, that CRP values are clearly elevated during infections with fever and inflammatory processes, but not in the case of catarrh and diarrhoea. The pathomorphological investigations of some animals with clinical findings revealed changes in lungs, bowels and liver. Special attention has to be paid to the fact that, as in man, CRP is an acute phase reactant, and therefore a sensitive, but non-specific indicator for infections and inflammation processes. Serum CRP screening seems to be a good means for the supervision of the general state of health in pigs.

The rat female protein, a pentraxin with lectinic properties

The C-reactive protein is the major acute phase protein (APP) in humans which binds lectin-like to different membraneous structures and exerts an important function in non-specific defense. Because of a pentameric molecular symmetry CRP as well as serum amyloid P component (SAP) and hamster female protein (FP) was merged into a special protein family named pentraxins. In rats a protein was found referred to as rat FP which was close related to hamster FP with respect to hormonal regulation and APP nature as well. Based on this conformity the molecular structure of rat FP was analyzed and as the results a pentameric structure could be demonstrated for rat FP, too. Furthermore, the response of rat CRP and FP on injection of adrenal hormones, agents being involved in acute phase reaction, was investigated. Epinephrine administration led to an increase in CRP and a decrease in FP serum concentration. Dexamethasone has the same effect in case of FP and changed the CRP concentration in a biphasic way with a maximum at about 0.01 mg/kg, a minimum at 0.6 mg/kg and a return to control values at 1.8 mg/kg. Thus, the results indicate a neuroendocrine control of CRP and FP but probably in a different way. Using FITC-labelled lectin the exposition of galactose-containing membraneous structures could be demonstrated in carbon tetrachloride-injured liver tissue in contrast to controls. These binding sites are in accordance with increased FP-binding shown by immunofluorescence histochemistry. Thus, lectin-like properties may be ascribed to rat FP comparable to CRP and SAP activity. The results are discussed with respect to findings from literature that also the acetylcholine receptor seems to have a pentameric structure.

Estrogen induction of hepatocellular carcinomas in Armenian hamsters

Liver tumors were found in most Armenian hamsters (Cricetulus migratorius) injected with on 15-mg pellet of diethylstilbestrol. The tumors were detectable as early as 1 1/2 mo after diethylstilbestrol administration and were usually present as multiple nodules that progressively increased in size. Histologically, the multicentric neoplasms were all hepatocellular carcinomas of varied degrees of differentiation and frequently (42.8%) contained Mallory bodies; preneoplastic lesions were not observed. This hepatocellular carcinoma hamster model is unique because estrogen alone without any other known mutagen is responsible for induction of hepatocellular carcinoma.

Amyloidosis and female protein in the Syrian hamster. Concurrent regulation by sex hormones

Previous results have shown that when compared to male Syrian hamsters, female Syrian hamsters have a distinct predisposition to acquire amyloidosis either normally with aging or experimentally with sodium caseinate or diethylstilbestrol (DES) treatments. In the present study, we tested the influence of testosterone on expression of amyloid to determine if this hormone was solely responsible for the sex-limited amyloidosis of the Syrian hamster. Males deprived of testosterone by castration acquired amyloid at an unusually young age, an age of onset similar to that in female hamsters. Also, the amyloidogenic effect of DES in male Syrian hamsters was inhibited by concomitant injections of testosterone, indicating that estrogens induce amyloid in male hamsters by inhibiting testosterone synthesis. When administered to female hamsters, testosterone inhibited expression of amyloid in aging female Syrian hamsters and extended the life span of this gender. Of the two components of amyloid, the major component Amyloid A-derived fibril or the minor constituent, Amyloid P component, only the P component is under sex hormone control in the Syrian hamster; testosterone inhibits the hepatic synthesis of the P component homologue (called female protein), which is normally expressed 100-200-fold greater in female vs. male Syrian hamster. In general, the serum level of female protein under various experimental conditions correlated with the presence of amyloid and indicated that in the Syrian hamster the P component homologue is of primary importance in the deposition of amyloid.

Effect of rat phosphorylcholine-binding protein on platelet aggregation

Rat serum phosphorylcholine-binding protein (PCBP), also referred to as rat C-reactive protein, is present in serum under normal physiological conditions. In the present study, PCBP is shown to inhibit, in a dose-dependent manner, ADP- and platelet-activating factor (PAF)-induced platelet aggregation, using either washed rat platelets or platelet-rich plasma from rats or humans. Rat platelets, as expected, were refractory to aggregation by PAF. However, when rabbit antiserum against PCBP was added to rat platelet-rich plasma, it resulted in aggregation of platelets by PAF. PCBP also inhibited the PAF-induced aggregation of human platelets in a dose-dependent manner. The inhibition of ADP-induced platelet aggregation by PCBP was reversed by adding phosphorylcholine. Our results suggest that PCBP present in rat serum could be the cause of the refractory response of rat plasma to PAF. It is possible that PCBP inhibits platelet aggregation by binding to the platelet surface phospholipids.

The rat C-reactive protein--isolation and response to experimental inflammation and tissue damage

A new isolation procedure of rat C-reactive protein (CRP) by affinity chromatography on amino-coupled phosphorylcolamine-Sepharose is described. CRP serum level of rats injured by turpentine injection or two different arthritis models was determined to test the potency of this protein as an marker of inflammation. The influence of repeated administration of carbon tetrachloride as a hepatotoxic agent was investigated in the same way. It was shown that CRP determination is a useful method to observe the course of experimental inflammations and other tissue injuries as well.

Hamster female protein, a sex-limited pentraxin, is a constituent of Syrian hamster amyloid

Female protein (FP) is a pentraxin of Syrian hamster which is a homologue of two human pentraxins, C-reaction protein (CRP) and amyloid P component (AP). Functionally, FP has been shown to be similar to CRP, although FP has more homology at the amino terminus with AP. The present work investigated amyloid in the Syrian hamster to determine whether FP was involved in a manner analogous to AP. FP was found to be a constituent of Syrian hamster amyloid. This conclusion was based on the following results: (a) FP was consistently detected in amyloid deposits by fluorescent microscopy with specific antisera; (b) The amount of FP extractable from hamster livers directly correlated with the presence of amyloid; and (c) 125I-FP injected intravenously into amyloidotic hamsters rapidly left the intravascular compartment and was found subsequently in amyloid deposits. This unusual alteration of plasma metabolism and amyloid localization of 125I-FP was a characteristic finding in amyloidotic hamsters and was specific for 125I-FP. Therefore, as an amyloid component, FP appears to be functionally similar to human AP. However, FP synthesis is under sex steroid control and the unique sex-limited expression of this pentraxin was associated with an equally novel propensity for deposition of amyloid in female hamsters under normal or experimental conditions. Thus, a high serum level of FP, as found in normal females or diethylstilbestrol-treated males, was associated with enhanced amyloidosis. Although speculative at present, a primary role for serum FP in hamster amyloid deposition may be experimentally approachable by hormonal manipulation of FP synthesis.

Diethylstilbestrol-induced jaundice in the Chinese and Armenian hamster

An unusual and impressive hyperbilirubinemia was induced in Chinese hamsters by administration of diethylstilbestrol (DES). This icterus was dose-dependent and affected females more severely than males. However, a similar mortality was detected in both sexes. Another hamster, the Armenian hamster, was even more susceptible to the icteric and lethal effects of DES. The hamster model of DES-induced icterus showed many clinical dissimilarities when compared to the human estrogen-induced jaundice, simple cholestatic jaundice. Furthermore, hepatic pathology was distinctly different as canalicular cholestatic was absent although other degenerative and regenerative hepatocellular changes were present. Livers of Armenian hamsters were more severely affected than were livers from Chinese hamsters and contained Mallory bodies even within 1 week after DES treatment. A modest, nonlethal jaundice also was detected in European hamsters after DES injection, whereas Syrian hamsters were not affected even after larger doses. This unique sensitivity to DES, and the spectrum of sensitivity within these related hamsters (Armenian greater than Chinese greater than European vs. resistant Syrian) provide an interesting model for study of DES effect on hepatic function.