C-reactive protein: structural biology, gene expression, and host defense function

Identification of a distal enhancer that determines the expression pattern of acute phase marker C-reactive protein

C-reactive protein (CRP) is a major acute phase protein and inflammatory marker, the expression of which is largely liver specific and highly inducible. Enhancers are regulatory elements critical for the precise activation of gene expression, yet the contributions of enhancers to the expression pattern of CRP have not been well defined. Here, we identify a constitutively active enhancer (E1) located 37.7 kb upstream of the promoter of human CRP in hepatocytes. By using chromatin immunoprecipitation, luciferase reporter assay, in situ genetic manipulation, CRISPRi, and CRISPRa, we show that E1 is enriched in binding sites for transcription factors STAT3 and C/EBP-β and is essential for the full induction of human CRP during the acute phase. Moreover, we demonstrate that E1 orchestrates with the promoter of CRP to determine its varied expression across tissues and species through surveying activities of E1-promoter hybrids and the associated epigenetic modifications. These results thus suggest an intriguing mode of molecular evolution wherein expression-changing mutations in distal regulatory elements initiate subsequent functional selection involving coupling among distal/proximal regulatory mutations and activity-changing coding mutations.

Targeting C-Reactive Protein by Selective Apheresis in Humans: Pros and Cons

C-reactive protein (CRP), the prototype human acute phase protein, may be causally involved in various human diseases. As CRP has appeared much earlier in evolution than antibodies and nonetheless partly utilizes the same biological structures, it is likely that CRP has been the first antibody-like molecule in the evolution of the immune system. Like antibodies, CRP may cause autoimmune reactions in a variety of human pathologies. Consequently, therapeutic targeting of CRP may be of utmost interest in human medicine. Over the past two decades, however, pharmacological targeting of CRP has turned out to be extremely difficult. Currently, the easiest, most effective and clinically safest method to target CRP in humans may be the specific extracorporeal removal of CRP by selective apheresis. The latter has recently shown promising therapeutic effects, especially in acute myocardial infarction and COVID-19 pneumonia. This review summarizes the pros and cons of applying this novel technology to patients suffering from various diseases, with a focus on its use in cardiovascular medicine.

CHARACTERISTICS OF IRON-DEPENDENT PARAMETERS OF DONORS UNDER THE PRESENCE OF ANTI-SARS-CoV-2 IgG IN THE BLOOD

COVID-19 differs from other respiratory diseases in that it can cause an acute inflammatory reaction following widespread systemic complications in organisms. First, the inflammatory process causes an increase in the concentration of C-reactive protein (CRP), which could be a prognostic biomarker in patients with COVID-19. In addition, some clinical data were used to determine changes in the concentrations of ferritin and transferrin. Our study aimed to establish a relationship between the inflammatory process and iron-dependent parameters, as changes in concentration could lead to pathological status in the post-COVID-19 period. People suffered from COVID-19 with different titers of anti-SARS-CoV-2 IgG in the blood participated in our experiment. It was established that the maximal concentration of CRP and ferritin was characterized for the donor group with a titer of anti-SARS-CoV-2 IgG 95 ± 5 Index (S/C) following the development of inflammatory anemia. Moreover, it was discovered that the group with a minimal titer of anti-SARS-CoV-2 IgG was characterized by the maximal concentration of transferrin, leading to the destruction of iron transport. Due to the acute inflammatory process and damage to the transport and storage of iron by transferrin and ferritin, the iron deficit could destroy the functioning of the muscle system. There was a change in the concentration of creatine kinase in the donor group with a titer of anti-SARS-CoV-2 IgG of 95 ± 5 Index (S/C). The study showed that infection with the SARS-CoV-2 virus in the body often leads to the development of acute inflammatory reactions, resulting in iron transport and storage processes, which cause pathological processes in the post-COVID-19 period.

Crosslinking of human plasma C-reactive protein to human serum albumin via disulfide bond oxidation

Inter- and intra-molecular crosslinks can generate protein dysfunction, and are associated with protein aggregate accumulation in aged and diseased tissues. Crosslinks formed between multiple amino acid side chains can be reversible or irreversible. Disulfides formed either enzymatically, or as a result of oxidant-mediated reactions, are a major class of reversible crosslinks. Whilst these are commonly generated via oxidation of Cys thiol groups, they are also formed by ‘oxidant-mediated thiol-disulfide reactions’ via initial disulfide oxidation to a thiosulfinate or zwitterionic peroxide, and subsequent reaction with another thiol including those on other proteins. This generates new intermolecular protein-protein crosslinks. Here we demonstrate that photooxidation, or reaction with the biological oxidants HOCl and ONOOH, of the single disulfide present in the major human plasma inflammatory protein, C-reactive protein (CRP) can give rise to reversible disulfide bond formation with human serum albumin (HSA). This occurs in an oxidant dose-, or illumination-time-, dependent manner. These CRP-HSA crosslinks are formed both in isolated protein systems, and in fresh human plasma samples containing high, but not low, levels of CRP. The inter-protein crosslinks which involve Cys36 of CRP and Cys34 of HSA, have been detected by both immunoblotting and mass spectrometry (MS). The yield of protein-protein crosslinks depends on the nature and extent of oxidant exposure, and can be reversed by dithiothreitol and tris(2-carboxyethyl)phosphine hydrochloride. These data indicate that oxidation of disulfide bonds in proteins can be a source of novel inter-protein crosslinks, which may help rationalize the accumulation of crosslinked proteins in aged and diseased tissues.

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C-reactive protein (CRP) is a major acute phase inflammatory protein in human plasma.

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Oxidation of the single Cys36-Cys97 disulfide in CRP generates reactive intermediates.

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The oxidized disulfide reacts with Cys34 of human serum albumin to forms a new crosslink.

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The inter-protein CRP-HSA crosslink has been characterized by immunoblotting and LS-MS/MS.

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This novel crosslink may be a long-lived plasma marker of inflammation-induced damage.

Formation of protein cross-links by singlet oxygen-mediated disulfide oxidation

Cross-links formed within and between proteins are a major cause of protein dysfunction, and are postulated to drive the accumulation of protein aggregates in some human pathologies. Cross-links can be formed from multiple residues and can be reversible (usually sulfur-sulfur bonds) or irreversible (typically carbon-carbon or carbon-heteroatom bonds). Disulfides formed from oxidation of two Cys residues are widespread, with these formed both deliberately, via enzymatic reactions, or as a result of unintended oxidation reactions. We have recently demonstrated that new protein-glutathione mixed disulfides can be formed through oxidation of a protein disulfide to a thiosulfinate, and subsequent reaction of this species with glutathione. Here we investigate whether similar reactions occur between an oxidized protein disulfide, and a Cys residues on a second protein, to give novel protein cross-links. Singlet oxygen (¹O₂)-mediated oxidation of multiple proteins (α-lactalbumin, lysozyme, beta-2-microglobulin, C-reactive protein), and subsequent incubation with the Cys-containing protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH), generates inter-protein cross-links as detected by SDS-PAGE, immunoblotting and mass spectrometry (MS). The cross-link yield is dependent on the ¹O₂ concentration, the presence of the original protein disulfide bond, and the free Cys on GAPDH. MS with ¹⁸O-labeling has allowed identification of the residues involved in some cases (e.g. Cys25 from the Cys25-Cys80 disulfide in beta-2-microglobulin, with Cys149 or Cys244 of GAPDH). The formation of these cross-links results in a loss of GAPDH enzymatic activity. These data provide 'proof-of-concept' for a novel mechanism of protein cross-link formation which may help rationalize the accumulation of cross-linked proteins in multiple human pathologies.

An overview on human serum lectins

An extensive literature survey done on the various naturally occurring lectins in human serum upon its salient features such as methods of detection, level and sites of synthesis, binding specificity, cation dependency, modes of isolation, molecular and functional characterization way back from 1930s to till date was presented in a tabulated section. In addition, the generation of lectin and other immune molecules in vertebrates upon treatment with exogenous elicitors has also been framed in a tabular form. Furthermore, ANEW lectin induced in human serum for the very first time by an exogenous elicitor was detected, isolated and characterized by us whose features are also tabulated explicitly.

[Preprocedural high - sensitivity C-reactive protein (hsCRP) decrease during intensive atorvastatin therapy: the presumable impact on atherosclerosis progression after coronary stenting]

Proinflammatory status is the risk factor for coronary atherosclerosis progression after coronary stenting (CS). Intensive statin treatment is associated with hsCRP concentration decline.

AIM

to evaluate prognostic significance of preprocedural hsCRP level reduction with intensive statin regimen for coronary atherosclerosis progression during one year after CS.

MATERIALS AND METHODS

We enrolled 102 patients with stable angina who were on list for scheduled CS. Group I (n=37) patients received atorvastatin 80 mg for 7 days before and 3 months after CS with further dose adjustment according to LDL; group II (n=65) patients received atorvastatin 20-40 mg/day for LDL goal achievement. HsCRP level was assessed at baseline, before CS and after 1, 3, 6 and 12 months. Coronary atherosclerosis progression was defined as new ≥50% stenosis or ≥30% increase of ≥20% pre - existing stenosis according to coronary angiography (CA) 1 year after CS.

RESULTS

Baseline concentration of hsCRP was comparable: 0.21 (0.13; 0.38) vs. 0.20 (0.1; 0.44) mg/dl in groups I and II, respectively (p>0.05). In group I significant hsCRP level decrease to 0.14 (0.07; 0.32) mg/dl (p.

Toward Early Diagnosis of Late-Onset Sepsis in Preterm Neonates: Dual Magnetoimmunosensor for Simultaneous Procalcitonin and C-Reactive Protein Determination in Diagnosed Clinical Samples

Early diagnosis of sepsis, combining blood cultures and inflammation biomarkers, continues to be a challenge, especially in very low birth weight (VLBW) infants because of limited availability of blood samples. Traditional diagnostic procedures are cumbersome, not fast enough, and require relatively large volumes of sample. Empiric use of antibiotics, before diagnostic confirmation, is required to decrease mortality, leading to potential antibiotic resistance and side effects in VLBW infants. To solve such a serious problem, a dual magnetoimmunosensor is proposed for simultaneous assessment of two of the most important sepsis biomarkers: procalcitonin (PCT for early phase) and C-reactive protein (CRP for late phase). This "sample-to-result" approach exhibited excellent sensitivity, selectivity, precision, and stability using low sample volumes (<30 μL) and under 20 min of total assay. The analytical usefulness of the approach was demonstrated by analyzing clinically relevant samples of preterm neonates with suspicion of sepsis.

Phase Variation of Streptococcus pneumoniae

Streptococcus pneumoniae undergoes phase variation or spontaneous, reversible phenotypic variation in colony opacity, encapsulation, and pilus expression. The variation in colony opacity appears to occur in all strains, whereas the switches in the production of the capsule and pilus have been observed in several strains. This chapter elaborates on the variation in colony opacity since this phenomenon has been extensively characterized. S. pneumoniae produces opaque and transparent colonies on the translucent agar medium. The different colony phases are fundamentally distinct phenotypes in their metabolism and multiple characteristics, as exemplified by cell surface features and phenotypes in colonization and virulence. Opaque variants, which express more capsular polysaccharides and fewer teichoic acids, are more virulent in animal models of sepsis but colonize the nasopharynx poorly. In contrast, transparent variants, with fewer capsular polysaccharides and more teichoic acid, colonize the nasopharynx in animal models more efficiently but are relatively avirulent. Lastly, pneumococcal opacity variants are generated by differential methylation of the genome DNA variation. The reversible switch in the methylation pattern is caused by DNA inversions in three homologous hsdS genes of the colony opacity determinant ( cod ) or SpnD39III locus, a conserved type I restriction-modification (RM) system. The hsdS gene encodes the sequence recognition subunit of the type I RM DNA methyltransferase. The combination of DNA inversion and differential methylation, a complex mechanism of phase variation, generates a mixed population that may allow for the selection of organisms in vivo with characteristics permissive for either carriage or systemic infection.

Postprandial lipemic and inflammatory responses to high-fat meals: a review of the roles of acute and chronic exercise

Postprandial lipemia is an independent risk factor for development of cardiovascular disease. Postprandial inflammation following the prolonged elevation of triglycerides occurring subsequent to ingestion of high-fat meals, provides a likely explanation for increased disease risk. Substantial evidence has shown that acute exercise is an effective modality for attenuation of postprandial lipemia following a high-fat meal. However, much of the evidence pertaining to exercise intensity, duration, and overall energy expenditure for reducing postprandial lipemia is inconsistent. The effects of these different exercise variables on postprandial inflammation is largely unknown. Long-term, frequent exercise, however, appears to effectively reduce systemic inflammation, especially in at-risk or diseased individuals. With regard to an acute postprandial response, without a recent bout of exercise, high levels of chronic exercise do not appear to reduce postprandial lipemia. This review summarizes the current literature on postprandial and inflammatory responses to high-fat meals, and the roles that both acute and chronic exercise play. This review may be valuable for health professionals who wish to provide evidence-based, pragmatic advice for reducing postprandial lipemia and cardiovascular disease risk for their patients. A brief review of proposed mechanisms explaining how high-fat meals may result in pro-inflammatory and pro-atherosclerotic environments is also included.

C-reactive protein in human atherogenesis: facts and fiction

The role of C-reactive protein (CRP) in atherosclerosis is controversially discussed. Whereas initial experimental studies suggested a pathogenic role for CRP in atherogenesis, more recent genetic data from Mendelian randomization trials failed to provide evidence for a causative role of CRP in cardiovascular disease. Also, experimental results from laboratories all over the world were indeed contradictory, partly because of species differences in CRP biology and partly because data were not accurately evaluated. Here we summarize the published data from experimental work with mainly human material in order to avoid confusion based on species differences in CRP biology. Experimental work needs to be reevaluated after reconsideration of some traditional rules in research: (1) in order to understand a molecule's role in disease it may be helpful to be aware of its role in physiology; (2) it is necessary to define the disease entity that experimental CRP research deals with; (3) the scientific consensus is as follows: do not try to prove your hypothesis. Specific CRP inhibition followed by use of CRP inhibitors in controlled clinical trials may be the only way to prove or disprove a causative role for CRP in cardiovascular disease.

Possible potentiation by certain antioxidants of the anti-inflammatory effects of diclofenac in rats

In the present study, we investigated the potential beneficial impact of the addition of antioxidant supplements to diclofenac regimen in a model of carrageenan-induced paw. Rats were treated daily with antioxidants, that is, a-lipoic acid (50 mg/kg), selenium (2.5 mg/kg), vitamin C (1 g/kg), vitamin E (300 mg/kg), or zinc (25 mg/kg) on seven successive days and then received a single treatment with diclofenac or saline before carrageenan was injected to induce paw inflammation. The results indicated that these combinations did not significantly affect the percentage inhibition of paw edema caused by diclofenac alone; however, some combination treatments ameliorated signs of concomitant oxidative stress (such as alterations in plasma malondialdehyde (MDA) levels, hemolysate reduced glutathione levels, and erythrocytic superoxide dismutase enzyme activities) imparted by diclofenac alone. In some cases, few tested antioxidants in combination with diclofenac resulted in increased plasma levels of interleukin- (IL-) 6 and C-reactive protein (CRP). In conclusion, the results of these studies suggested to us that the added presence of natural antioxidants could be beneficial as standard anti-inflammatory therapeutics for a patient under diclofenac treatment, albeit that these effects do not appear to significantly build upon those that could be obtained from this common anti-inflammatory agent per se.

Interleukin-6 (IL-6) and C-reactive protein (CRP) concentration prior to total nephrectomy are prognostic factors in localized renal cell carcinoma (RCC)

BACKGROUND

Radical nephrectomy is the gold standard for treatment of renal cell carcinoma (RCC), but even for localized disease the survival rates are still unsatisfactory. Identification of prognostic factorsl is the basis for future treatment strategies for an individual patient.

AIM

The aim of our study was to assess the usefulness of the concentration of IL-6 and CRP as prognostic factors in patients after nephrectomy due to localized RCC.

MATERIALS AND METHODS

Our prospective study included 89 patients (55 men and 34 women) who had been surgically treated for RCC. The examined group included patients with localized advanced disease (from T1 to T3) with no metastases in lymph nodes (N0), and with no distant metastases (M0). All patients had blood samples drawn three times during the study (one day before surgery, six days after surgery and 6 months after surgery) to evaluate the concentration of CRP and IL-6. In each patient RCC of the kidney was removed during radical nephrectomy. Statistical analysis was conducted using statistica v.7.0.

RESULTS

Statistically significant relationships were found between the concentration of CRP before the operation and OS (p = 0.0001). CRP concentration at baseline was statistically significantly correlated with CSS (p = 0.0004). The level of IL-6 assessed before the surgery was significantly correlated with survival times such as OS (p = 0.0096) and CSS (p = 0.0002). The concentration of IL-6 and CRP measured 6 days after surgery and 6 months after surgery were not statistically significantly correlated with survival times.

CONCLUSIONS

Results of our study showed that elevated levels of IL-6 and CRP in peripheral blood before surgery of RCC were correlated with worse OS and CSS.

CRP identifies homeostatic immune oscillations in cancer patients: a potential treatment targeting tool?

The search for a suitable biomarker which indicates immune system responses in cancer patients has been long and arduous, but a widely known biomarker has emerged as a potential candidate for this purpose. C-Reactive Protein (CRP) is an acute-phase plasma protein that can be used as a marker for activation of the immune system. The short plasma half-life and relatively robust and reliable response to inflammation, make CRP an ideal candidate marker for inflammation. The high- sensitivity test for CRP, termed Low-Reactive Protein (LRP, L-CRP or hs-CRP), measures very low levels of CRP more accurately, and is even more reliable than standard CRP for this purpose. Usually, static sampling of CRP has been used for clinical studies and these can predict disease presence or recurrence, notably for a number of cancers. We have used frequent serial L-CRP measurements across three clinical laboratories in two countries and for different advanced cancers, and have demonstrated similar, repeatable observations of a cyclical variation in CRP levels in these patients. We hypothesise that these L-CRP oscillations are part of a homeostatic immune response to advanced malignancy and have some preliminary data linking the timing of therapy to treatment success. This article reviews CRP, shows some of our data and advances the reasoning for the hypothesis that explains the CRP cycles in terms of homeostatic immune regulatory cycles. This knowledge might also open the way for improved timing of treatment(s) for improved clinical efficacy.

Complexity of complement activation in sepsis

The complement system is one of the key players in the defence against infections. Its activation during the innate immune response leads to the generation of several proteins that contribute to the lysis and opsonization of microorganisms, regulate inflammatory reactions and bridge innate immunity with the subsequent adaptive immune response. Complement is also activated in overwhelming bacterial infections that lead to sepsis, and its protective functions play a role in this frequently lethal disorder. However, despite its role in protection, complement can also contribute to the development of severe complications that significantly worsen the prognosis of septic patients. Therefore, an understanding of the mechanisms involved in the activation of complement during sepsis is essential to our efforts to introduce rational therapies targeting complement to the treatment of patients suffering from this condition. This review presents a current view of the mechanisms involved in the activation of complement in sepsis, in the context of the multiple interactions between complement and other biological systems that are involved in the pathogenesis of this disorder.

Racial differences in C-reactive protein levels during normal pregnancy

OBJECTIVE

The purpose of this study was to characterize serum C-reactive protein (CRP) levels in a diverse population of healthy pregnant women with the use of a high sensitivity assay.

STUDY DESIGN

We conducted a cross-sectional analysis of a cohort of 775 pregnant women. CRP was measured on serum specimens that were drawn at < 26 weeks of gestation with highly sensitive enzyme-linked immunosorbent assay kits.

RESULTS

Median CRP was 4.8 mg/L (interquartile range, 0.63-15.7). Black women had higher median CRP values than did white women (7.68 vs 2.59 mg/L; P < .001). Black women demonstrated higher levels of CRP, even after the data were controlled for known confounding factors such as smoking and maternal weight.

CONCLUSION

Pregnancy is an inflammatory stressor. The cause of racial differences is unclear but may be important for understanding racial disparities in the incidence of inflammatory disorders such as preterm labor and preeclampsia.

Tenascin-W, a new marker of cancer stroma, is elevated in sera of colon and breast cancer patients

Tenascins are extracellular matrix proteins present during the development of organisms as well as in pathological conditions. Tenascin-W, the fourth and last member of the tenascin family remains the least well-characterized one. Our study aimed to evaluate the potential significance of tenascin-W as cancer biomarker by monitoring its presence in the serum of colorectal and breast cancer patients and its expression in colorectal tumor tissues. To measure serum tenascin-W levels, a sensitive sandwich-ELISA was established. Mean tenascin-W concentration in sera of patients with nonmetastatic colorectal cancer at time of diagnosis was highly increased compared to that of healthy volunteers. A similar tendency was observed for tenascin-C in the same patient cohort. However, the increase was much more striking for tenascin-W. We also detected elevated tenascin-W levels in sera of breast cancer patients. Furthermore, we could show a prominent expression of tenascin-W in extracts from colorectal tumor tissues by immunoblot analysis, whereas tenascin-W was not detectable in the corresponding normal colon mucosa. To confirm the western blot results, we performed immunohistochemistry of frozen sections of the same patients as well as of an additional, independently chosen collection of colorectal cancer tissues. In all cases, similarly to tenascin-C, tenascin-W was detected in the tumor stroma. Our results reveal a clear association between elevated levels of tenascin-W and the presence of cancer. These results warrant further studies to evaluate the potential value of serum and tissue tenascin-W levels as diagnostic, prognostic or monitoring biomarker in colorectal, breast and possibly other solid cancers.

Exaggerated neointima formation in human C-reactive protein transgenic mice is IgG Fc receptor type I (Fc gamma RI)-dependent

Neointima formation after vascular injury is exaggerated in ovariectomized (OVX) human C-reactive protein transgenic mice (CRPtg) compared to nontransgenic mice (NTG). We tested the hypothesis that this CRP-mediated exacerbation requires IgG Fc receptors (Fc gamma Rs). OVX NTG, CRPtg, and CRPtg lacking Fc gamma RI, Fc gamma RIIb, Fc gamma RIII, or the common gamma chain (FcR gamma) had their common carotid artery ligated. Twenty-eight days later neointimal thickening in CRPtg/Fc gamma RI(-/-) and CRPtg/FcR gamma (-/-) was significantly less than in CRPtg and no worse than in NTG, whereas in CRPtg/Fc gamma RIIb(-/-) and CRPtg/Fc gamma RIII(-/-) neointimal thickness was equal to or greater than in CRPtg. Immunohistochemistry revealed human CRP in the neointima of CRPtg, but little or none was observed in those lacking Fc gamma RI or FcR gamma. Real-time reverse transcriptase-polymerase chain reaction demonstrated that Fc gamma R types I to III were expressed in the CRPtg arteries, with Fc gamma RI expression increasing by threefold after ligation injury. Levels of serum complement (C3), neointimal deposition of complement (C3d), and cellular composition (monocytes, macrophages, lymphocytes) in the neointima did not differ among the different CRPtg genotypes. However, by immunofluorescence a neointimal population of F4/80+CRP+ cells was revealed only in OVX CRPtg. The exaggerated response to vascular injury provoked by CRP in OVX CRPtg depends on Fc gamma RI and probably requires its expression by F4/80+ cells.

Carbohydrate ligands of human C-reactive protein: binding of neoglycoproteins containing galactose-6-phosphate and galactose-terminated disaccharide

Binding of carbohydrate ligand by human C-reactive protein (CRP), in both native form and structurally deviated form (neoCRP or mCRP), was investigated using galactose-6-phosphate (Gal6P)- and Galbeta3GalNAc-containing bovine serum albumin (BSA) derivatives. To this end, we synthesized glycosides of Gal6P and Galbeta3GalNAc that can potentially generate a terminal aldehyde group. omega-Aldehydo glycosides were then conjugated to BSA via reductive amination. Using these neoglycoproteins, we showed that: (1) Gal6P-BSA and Galbeta3GalNAc-BSA bound to both forms of CRP, the former with or without calcium and the latter only in the absence of calcium; (2) phosphate-containing ligands can be bound with or without calcium, but the binding is much stronger in the presence of calcium than in the absence, underscoring the importance of direct coordination of phosphate to two calcium ions observed in the X-ray structure of phosphorylcholine (PC)-CRP complex; (3) cross-inhibition studies further corroborated the hypothesis that binding sites of PC and sugar are contiguous; (4) while PC-BSA bound to the native CRP over a wide pH range of 4.5 to 9, all the carbohydrate ligands and protamine-BSA (poly-cation-based ligand) exhibited optimal binding at around pH 6 to 6.5; and (5) ligand-binding conformation of mCRP appears to be more fragile than that of the native CRP in the acidic media (pH < 6).

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.

Changes in hepatic gene expression related to innate immunity, growth and iron metabolism in GH-transgenic amago salmon (Oncorhynchus masou) by cDNA subtraction and microarray analysis, and serum lysozyme activity

Growth hormone (GH) transgenic amago salmon (Oncorhynchus masou) were generated with a construct containing the sockeye salmon GH1 gene fused to the metallothionein-B (MT-B) promoter from the same species. This transgene directed significant growth enhancement with transgenic fish reaching approximately four to five times greater weight than control salmon in F(2) and F(3) generations. This drastic growth enhancement by GH transgene is well known in fish species compared with mammals, however, such fish can show morphological abnormalities and physiological disorders like other GH transgenic animals. GH is known to have many acute effects, but currently there are no data describing the chronic effects of over-expression of GH on various hepatic genes in GH transgenic fish. Hepatic gene expression is anticipated to play very important roles in many physiological functions and growth performance of transgenic and control salmon. To examine these effects, we performed subtractive hybridization (using cDNA generated from liver RNA) in both directions to identify genes both increased and decreased in transgenic salmon relative to controls (576 clones were isolated and sequenced in total). Heme oxygenase, vitelline envelope protein, Acyl-coA binding protein, NADH dehydrogenase, mannose binding lectin-associated serine protease, hemopexin-like protein, leucyte-derived chemotaxin2 (LECT2), and many other genes were obtained in higher clone frequencies suggesting enhanced expression. In contrast, complement C3-1, lectin, rabin, alcohol dehydrogenase, Tc1-like transposase, Delta6-desaturase, and pentraxin genes were obtained in lower frequencies. Microarray analysis was also performed to obtain quantitative expression data for these subtracted cDNA clones. Analysis of fish across seasons was also conducted using both F(2) and F(3) salmon. Results of the microarray data essentially corresponded with those of the subtraction data when both F(2) and F(3) fish were completely immature, but the expression pattern was changed when fish approached maturation. Genes showing enhanced expression in GH transgenic fish in F(2) and F(3) by array analysis were vitelline envelope protein, hemopexin-like protein, heme-oxygenase, inter alpha-trypsin inhibitor, LECT2, GTP cyclohydrolase I feedback regulatory protein (GFRP), and bikunin. Reduced expression genes were lectin, Delta6-desaturase, apolipoprotein, and pentraxin. In particular, lectin was found to be highly suppressed in all F(2) and immature F(3) salmon. Further, serum lysozyme activity, one of innate immunity, was significantly (p<0.05) decreased in both F(2) and F(3) GH transgenic fish. These results indicate that the GH transgene fish had altered hepatic gene expression relating to iron-metabolism, innate immunity, reproduction, and growth.

A nuclear receptor corepressor-dependent pathway mediates suppression of cytokine-induced C-reactive protein gene expression by liver X receptor

C-reactive protein (CRP), the prototypical human acute phase protein, is an independent risk predictor of future cardiovascular events, both in healthy individuals and in patients with known cardiovascular disease. In addition, previous studies indicate that CRP might have direct proatherogenic properties. Ligand activation of the liver X receptor (LXR), a member of the nuclear hormone receptor superfamily, inhibits inflammatory gene expression in macrophages and attenuates the development of atherosclerosis in various animal models. We demonstrate herein that 2 synthetic LXR ligands, T0901317 and GW3965, inhibit interleukin-1beta/interleukin-6-induced CRP mRNA and protein expression in human hepatocytes. Knockdown of LXRalpha/beta by short interfering RNAs completely abolished the inhibitory effect of the LXR agonist T0901317 on cytokine-induced CRP gene transcription. Transient transfection experiments with 5'-deletion CRP promoter constructs identified a region from -125 to -256 relative to the initiation site that mediated the inhibitory effect of LXR ligands on CRP gene transcription. Depletion of the nuclear receptor corepressor by specific short interfering RNA increased cytokine-inducible CRP mRNA expression and promoter activity and reversed LXR ligand-mediated repression of CRP gene transcription. Chromatin immunoprecipitation assays indicated that nuclear receptor corepressor is present on the endogenous CRP promoter under basal conditions. Cytokine-induced clearance of nuclear receptor corepressor complexes was inhibited by LXR ligand treatment, maintaining the CRP gene in a repressed state. Finally, treatment of C57Bl6/J mice with LXR ligands attenuated lipopolysaccharide-induced mouse CRP and serum amyloid P component gene expression in the liver, whereas no effect was observed in LXRalphabeta knockout mice. Our observations identify a novel mechanism of inflammatory gene regulation by LXR ligands. Thus, inhibition of CRP expression by LXR agonists may provide a promising approach to impact initiation and progression of atherosclerosis.

Mannose-binding lectin does not act as an acute-phase reactant in adults with community-acquired pneumococcal pneumonia

The objective of this work was to study the role of mannose-binding lectin (MBL) and C-reactive protein (CRP) in pneumococcal pneumonia, to determine whether MBL acts as an acute-phase reactant and whether the severity of the disease correlates with MBL levels. The study comprised 100 patients with pneumococcal pneumonia. The pneumonia severity score was calculated and graded into a risk class of mortality (Fine scale). The MBL genotypes and the levels of MBL and CRP at the acute and recovery phases were determined. Fifty patients with the wild-type MBL genotype showed higher MBL levels in each phase (P < 0.001) and an increased risk to developing bacteraemia, odds ratio (OR) 2.74, 95% confidence interval (CI) 1.01-7.52) (P = 0.02), but this did not correlate with the pneumonia severity class. CRP levels in the acute phase, 79.53 mg/l [standard deviation (s.d.) 106.93], were higher in the subjects with positive blood cultures (P = 0.003), and remained higher [20.12 mg/l (s.d. 31.90)] in the group of patients with an underlying disease (P = 0.01). No correlation was observed between the levels of MBL and CRP in each phase, or with the pneumonia severity score. We cannot conclude that MBL acts uniformly as an acute-phase reactant in pneumococcal pneumonia. MBL levels do not correlate well with the severity of the pneumonia. The risk of developing bacteraemia could be enhanced in individuals with the wild-type MBL genotype.

Innate immunity and the pneumococcus

The innate immune system provides a non-specific first line of defence against microbes and is crucial both in the development and effector stages of subsequent adaptive immune responses. Consistent with its importance, study of the innate immune system is a broad and fast-moving field. Here we provide an overview of the recent key advances made in this area with relation to the important pathogen Streptococcus pneumoniae (the pneumococcus).

Interleukin-1alpha, interleukin-6 and tumor necrosis factor-alpha levels in children with sepsis and meningitis

BACKGROUND

Cytokines are thought to be important endogenous mediators of the host immune response to infection. The purpose of the present study was to evaluate the utility of serum levels of interleukin (IL)-1alpha, IL-6 and tumor necrosis factor (TNF)-alpha in the prediction and differentiation of sepsis and meningitis in children.

METHODS

Blood was collected from 50 children admitted to hospital for suspicion of infection. On the basis of predetermined criteria and investigation, the children were classified into sepsis (n = 30) and meningitis (n = 20) groups, as well as into healthy controls (n = 24) and non-infected sick controls (n = 12). The sepsis group was subdivided according to culture results into S1 (proven sepsis, n = 11) and S2 (clinical sepsis, n = 19). Serum IL-1alpha, IL-6 and TNF-alpha were measured by enzyme-linked immunosorbent assay (ELISA) while C-reactive protein (CRP) was measured by nephelometer.

RESULTS

In non-infected sick controls, sepsis and meningitis groups, levels of CRP (P < 0.001, P < 0.05 and P < 0.01, respectively), IL-1alpha (P < 0.001 for all), and IL-6 (P < 0.01, P < 0.001, P < 0.001, respectively) were significantly elevated compared to healthy controls. In sepsis, levels of IL-1alpha increased in the S2 subgroup (P < 0.001) and IL-6 increased in the S1 and S2 subgroups (P < 0.05, P < 0.001, respectively) compared with healthy controls. In meningitis, IL-1alpha had the highest sensitivity and negative predictive value, while IL-6 had the highest specificity and positive predictive value in non-infected sick controls, sepsis and meningitis groups.

CONCLUSION

Interleukin-1alpha, IL-6 and CRP are increased in non-infected sick controls, sepsis and meningitis patients but it is not possible to differentiate between them. IL-1alpha had the highest sensitivity in meningitis while IL-6 had the highest specificity in prediction of sepsis and meningitis and their assessment together may improve accuracy in the diagnosis of childhood infection.

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.

Mannose Binding Lectin Acute Phase Activity in Patients with Severe Infection

Mannose Binding Lectin (MBL) is a liver derived, circulating plasma protein that plays a pivotal role in innate immunity. MBL functions as a pathogen recognition molecule, opsonising organisms and initiating the complement cascade. MBL deficiency arising from mutations and promoter polymorphisms in the MBL2 gene is common and has been associated with risk, severity, and frequency of infection in a number of clinical settings. With MBL therapy on the horizon, the usefulness of replacement MBL therapy has been challenged by the notion, that as an acute phase protein, MBL levels may rise under stress to sufficient levels, in individuals who are usually deficient. This report demonstrates that in patients with sepsis and septic shock, the majority of patients do not display an MBL acute phase response: 41.4% of individuals maintained consistent MBL levels throughout hospital stay, 31.3% of individuals demonstrated a positive acute phase response, and a negative acute phase response was observed in 27.3% of individuals studied. Importantly, a positive acute phase response was generally observed in individuals with wild-type MBL2 genes. When a positive acute phase response was observed in individuals with coding mutation, these individuals demonstrated a normal MBL level on admission to hospital. Furthermore, no individual, regardless of genotype who was MBL deficient at admission was able to demonstrate a positive acute phase response into the normal MBL range. These findings indicate MBL demonstrates a variable acute phase response in the clinical setting of sepsis and septic shock.

Macrophage conditioned medium induces the expression of C-reactive protein in human aortic endothelial cells: potential for paracrine/autocrine effects

C-reactive protein (CRP) is a risk marker for cardiovascular events in apparently healthy persons. Cogent data show that, aside from the liver, CRP is produced in atherosclerotic lesions, kidney, neurons, and alveolar macrophages. Because several proatherogenic effects of CRP have been documented in endothelial cells, we examined human aortic endothelial cells (HAEC) for CRP production. We detected the presence of CRP mRNA by RT-PCR and in situ hybridization, intracellular protein by Western blot and secreted protein by ELISA. Coincubation with the cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor alone and in combination showed that the most potent agonist for CRP production from HAEC is the combination of IL-1 and IL-6 (P < 0.05). To mimic the in vivo situation, we examined whether vascular smooth muscle cell (VSMC) and/or macrophage conditioned media (MCM) could augment CRP production by HAEC. While VSMC-conditioned media had no effect, incubation with MCM resulted in a significant twofold increase in the synthesis of both intracellular and secreted CRP (P < 0.05). The effect of MCM could be reversed by inhibiting both IL-1 and IL-6. Thus, stimulated synthesis and secretion of CRP by cells in the atherosclerotic lesion by paracrine/autocrine loops could result in local concentrations of CRP far in excess of plasma concentrations and could contribute to proinflammatory, proatherogenic effects.

C-reactive protein and end-stage renal disease

The significance of CRP and inflammation has increased over time, especially in the end-stage renal disease (ESRD) population. From a simple marker it now appears that CRP is an active participant in pro-atherosclerotic phenomenon including local pro-inflammatory and thrombotic events. Studies in the general population indicate the usefulness of CRP in prognostication and in monitoring response to therapy. The clinical usefulness of CRP monitoring in chronic kidney disease (CKD) and especially in ESRD deserves closer study. In the meantime, the utility of CRP measurements for monitoring and treatment is on a case-by-case basis. Management of traditional cardiovascular risk factors should be considered. In the interest of optimizing therapy it is prudent to use biocompatible membranes and ultrapure water. A careful search for infectious processes in dialysis patients is recommended, with special attention to vascular access sites, periodontitis, gastritis, and other potentially chronic or covert infections. ACE-inhibitor use should be maximized in all eligible CKD patients. The data on the use of statins in ESRD have been generally positive but await further validation. Individualized use for selected patients is probably beneficial.

The role of inflammation in Alzheimer's disease

Considerable evidence gained over the past decade has supported the conclusion that neuroinflammation is associated with Alzheimer's disease (AD) pathology. Inflammatory components related to AD neuroinflammation include brain cells such as microglia and astrocytes, the classic and alternate pathways of the complement system, the pentraxin acute-phase proteins, neuronal-type nicotinic acetylcholine receptors (AChRs), peroxisomal proliferators-activated receptors (PPARs), as well as cytokines and chemokines. Both the microglia and astrocytes have been shown to generate beta-amyloid protein (Abeta), one of the main pathologic features of AD. Abeta itself has been shown to act as a pro-inflammatory agent causing the activation of many of the inflammatory components. Further substantiation for the role of neuroinflammation in AD has come from studies that demonstrate patients who took non-steroidal anti-inflammatory drugs had a lower risk of AD than those who did not. These same results have led to increased interest in pursuing anti-inflammatory therapy for AD but with poor results. On the other hand, increasing amount of data suggest that AChRs and PPARs are involved in AD-induced neuroinflammation and in this regard, future therapy may focus on their specific targeting in the AD brain.

The complement system in regulation of adaptive immunity

The serum complement system, which represents a chief component of innate immunity, not only participates in inflammation but also acts to enhance the adaptive immune response. Specific activation of complement via innate recognition proteins or secreted antibody releases cleavage products that interact with a wide range of cell surface receptors found on myeloid, lymphoid and stromal cells. This intricate interaction among complement activation products and cell surface receptors provides a basis for the regulation of both B and T cell responses. This review highlights fundamental events, explaining how complement links innate and adaptive immunity as well as describing more recent studies on how this large family of proteins functions locally in peripheral lymph nodes to enhance B and T cell responses.

The aging male: testosterone deficiency and testosterone replacement. An up-date

The significance of the age-related decline of androgens remains unclear in terms of cardiovascular risk, mood and cognition, and prostatic health. Although much research has been undertaken in this area and men's health has received still more attention in the latest years, there are no data based on randomized controlled clinical studies in aging men investigating the long-term effects of androgen replacement therapy on various aspects of the cardiovascular system, the immune system, body composition, and the brain. In men receiving long-term androgen replacement therapy, the safety aspects regarding the prostate are also an area of clinical importance. In this paper we present an up-dated review of the experimental and clinical evidence of androgen deficiency and androgen replacement therapy on carbohydrate metabolism, on coagulation and fibrinolysis, inflammatory effects, effects on lipoprotein metabolism, direct arterial effects, effects on body composition, effects on cognitive function and mood, and prostatic effects. The evidence clearly shows that data for the most part are conflicting, with only very few randomized studies available.

Apoptosis, subcellular particles, and autoimmunity

Firm evidence links the process of apoptosis to the induction of autoimmune disease. However, questions remain regarding the precise interactions of dying cells with the immune system. Genetic analyses indicate that deficiencies in serum proteins or receptors that mediate clearance of apoptotic cells increase the risk of autoimmunity. Moreover, administration of apoptotic cells to naive animals elicits transient autoimmune responses. Because known autoantigens are covalently modified and redistributed to cell surface blebs during the execution stage of apoptosis, increasing attention is being directed at this stage of programmed cell death, and researchers have identified a variety of autoantigens that are sequestered within blebs. However, blebs are merely a transition stage toward the complete cellular fragmentation, as blebs quickly convert into apoptotic bodies, subcellular particles (SCPs) of heterogeneous size, surface composition, and cargo. Because certain types of subcellular particles represent packets of highly enriched autoantigens, we propose that they are relevant to our understanding of autoimmunity.

PTX3 plays a key role in the organization of the cumulus oophorus extracellular matrix and in in vivo fertilization

PTX3 is a prototypic long pentraxin that plays a non-redundant role in innate immunity against selected pathogens and in female fertility. Here, we report that the infertility of Ptx3(-/-) mice is associated with severe abnormalities of the cumulus oophorus and failure of in vivo, but not in vitro, oocyte fertilization. PTX3 is produced by mouse cumulus cells during cumulus expansion and localizes in the matrix. PTX3 is expressed in the human cumulus oophorus as well. Cumuli from Ptx3(-/-) mice synthesize normal amounts of hyaluronan (HA), but are unable to organize it in a stable matrix. Exogenous PTX3 restores a normal cumulus phenotype. Incorporation in the matrix of inter-alpha-trypsin inhibitor is normal in Ptx3(-/-) cumuli. PTX3 does not interact directly with HA, but it binds the cumulus matrix hyaladherin tumor necrosis factor alpha-induced protein 6 (TNFAIP6, also known as TSG6) and thereby may form multimolecular complexes that can cross-link HA chains. Thus, PTX3 is a structural constituent of the cumulus oophorus extracellular matrix essential for female fertility.

Inter-relationships between rheumatoid arthritis and periodontal disease. A review

This review considers the considerable similarities between periodontal disease and rheumatoid arthritis (RA). While the etiology of these two diseases may differ, the underlying pathogenic mechanisms are remarkably similar and it is possible that individuals manifesting both periodontitis and RA may suffer from a unifying underlying systemic dysregulation of the inflammatory response. In light of these findings, the implications for the use of disease-modifying medications in the management of these two chronic inflammatory conditions is apparent. Further longitudinal studies and medication-based intervention studies are required to determine just how closely these two conditions are allied.

Intensive insulin therapy exerts antiinflammatory effects in critically ill patients and counteracts the adverse effect of low mannose-binding lectin levels

Adverse outcome of critical illness is often caused by systemic inflammation and sepsis. A recent study showed that mortality is significantly reduced by maintenance of normoglycemia using intensive insulin therapy. We examined whether the beneficial effects of intensive insulin therapy involve modulations of mannose-binding lectin (MBL) and C-reactive protein (CRP) levels. From a study of 1548 patients randomly assigned to either conventional treatment or intensive insulin therapy at an intensive care unit (ICU) we included all 451 patients who needed prolonged intensive care (>5 d). CRP and MBL concentrations were measured on admission, d 5, d 15, and the last day in the ICU. In all patients, serum MBL concentrations increased with time in the ICU (P < 0.0001). This acute phase response was suppressed by intensive insulin therapy at all time points studied (P < 0.02). Selectively in patients receiving conventional therapy, MBL concentrations at baseline were almost 3 times higher in survivors than in nonsurvivors (P = 0.04). Baseline CRP concentrations were elevated, but decreased with time in ICU (P < 0.0001). The decrease in CRP was significantly more pronounced in the intensive insulin-treated patients compared with the conventionally treated patients (P </= 0.02) at all time points. Multivariate logistic regression analysis, corrected for all other determinants of outcome, revealed that the antiinflammatory action on CRP, but not on MBL, largely explained the beneficial effects of intensive insulin therapy on morbidity and mortality. In conclusion, intensive insulin therapy exerts a powerful antiinflammatory effect during critical illness which at least partially explains improvement in morbidity and mortality. Possible adverse effects of low baseline MBL are overcome by intensive insulin therapy.

Fcgamma receptor IIA and IIIB polymorphisms are associated with susceptibility to cerebral malaria

Human FcgammaRIIA and FcgammaRIIIB exhibit genetic polymorphisms, FcgammaRIIA-131H/R and FcgammaRIIIB-NA1/NA2, coding for different capacities for IgG binding and phagocytosis. Recently, FcgammaRIIA-131R was reported to be associated with protection against high-density Plasmodium falciparum infection in Kenya. Furthermore, FcgammaRIIIB-NA1/NA2 polymorphism was shown to influence FcgammaRIIA function in an allele-specific manner. In this study, we examined a possible association of FcgammaRIIA-131H/R and FcgammaRIIIB-NA1/NA2 polymorphisms with malaria severity in 107 cerebral malaria patients, 157 non-cerebral severe malaria patients, and 202 mild malaria controls living in northwest Thailand. This study reveals that, with the FcgammaRIIIB-NA2 allele, the FcgammaRIIA-131H/H genotype is associated with susceptibility to cerebral malaria (OR 1.85, 95% CI 1.14-3.01; P=0.012), although these polymorphisms are not individually involved in the disease severity. Our results suggest that FcgammaRIIA-131H/R and FcgammaRIIIB-NA1/NA2 polymorphisms have an interactive effect on host defense against malaria infection.

Non-redundant role of the long pentraxin PTX3 in anti-fungal innate immune response

Pentraxins are a superfamily of conserved proteins that are characterized by a cyclic multimeric structure. The classical short pentraxins, C-reactive protein (CRP) and serum amyloid P component (SAP), are acute-phase proteins produced in the liver in response to inflammatory mediators. Short pentraxins regulate innate resistance to microbes and the scavenging of cellular debris and extracellular matrix components. In contrast, long pentraxins have an unrelated, long amino-terminal domain coupled to the carboxy-terminal pentraxin domain, and differ, with respect to short pentraxins, in their gene organization, chromosomal localization, cellular source, and in their stimuli-inducing and ligand-recognition ability. To investigate the in vivo function of the long pentraxin PTX3, we generated mice deficient in Ptx3 by homologous recombination. Ptx3-null mice were susceptible to invasive pulmonary aspergillosis. Ptx3 binds selected microbial agents, including conidia of Aspergillus fumigatus, and we found that susceptibility of Ptx3-null mice was associated with defective recognition of conidia by alveolar macrophages and dendritic cells, as well as inappropriate induction of an adaptive type 2 response. Thus, the long pentraxin Ptx3 is a secreted pattern-recognition receptor that has a non-redundant role in resistance to selected microbial agents, in particular to the opportunistic fungal pathogen Aspergillus fumigatus.

Direct modulatory effect of C-reactive protein on primary human monocyte adhesion to human endothelial cells

C-reactive protein (CRP) is the prototypic acute phase serum protein in humans. The effects of CRP on primary human monocyte adhesion molecule expression and interaction with the endothelium have not been studied. Herein, we describe an investigation into the phenotypic and functional consequences of CRP binding to peripheral blood monocytes ex vivo. Peripheral whole blood was collected from healthy, non-smoking males. Mononuclear cells (MNC) and monocytes were isolated by differential centrifugation using lymphoprep and Dynal negative isolation kit, respectively. Cells were exposed to CRP from 0 to 250 micro g/ml for 0-60 min at 37 degrees C and analysed for (a) CD11b, PECAM-1 (CD31) and CD32 expression by flow cytometry and (b) adhesion to LPS (1 micro g/ml; 0-24 h) treated human umbilical vein endothelial cells (HUVEC). CD14+ monocyte expression of CD11b increased significantly up to twofold when exposed to CRP, compared to controls. There was no significant difference in CD32 expression, whereas CD31 expression decreased after exposure to CRP. CRP treatment of monocytes inhibited their adhesion to early LPS-activated HUVEC (0-5 h). However, the adhesion of CRP-treated monocytes to HUVEC was significantly greater to late activation antigens on HUVEC (24 h, LPS) compared to controls. We have shown that CRP can affect monocyte activation ex vivo and induce phenotypic changes that result in an altered recruitment to endothelial cells. This study provides the first evidence for a further role for C-reactive protein in both monocyte activation and adhesion, which may be of importance during an inflammatory event.

In vitro leishmanicidal activity of a monoclonal antibody mimicking a yeast killer toxin

The microbicidal effect of a monoclonal antiidiotypic antibody, mimicking the activity of a yeast killer toxin, characterized by a wide antimicrobial spectrum, has been evaluated in vitro against two relevant species of protozoan parasites, Leishmania major and Leishmania infantum. The antiidiotypic antibody exerted a significant and dose-dependent antileishmanial activity against parasite promastigotes in comparison to an irrelevant isotype-matched monoclonal antibody. This is the first demonstration that an antibody, which had been already shown to be fungicidal and bactericidal, may also exert a direct microbicidal activity against protozoa.

Effects of C-reactive protein and pentosan polysulphate on human complement activation

Complement (C) activation is believed to play an adverse role in several chronic degenerative disease processes, including atherosclerosis, myocardial infarction and Alzheimer's disease. We developed several in vitro quantitative assays to evaluate processes which activate C in human serum, and to assess candidates which might block that activation. Binding of C-reactive protein (CRP) to immobilized cell surfaces was used as a tissue-based method of activation, while immunoglobulin G in solution was used as a surrogate antibody method. Activation was assessed by deposition of C fragments on fixed cell surfaces, or by capture of C5b-9 from solution. We observed that several cell lines, including SH-SY5Y, U-937, THP-1 and ECV304, bound CRP and activated C following attachment of cells to a plastic surface by means of air drying. Treatment of human neuroblastoma SH-SY5Y cells with the reactive oxygen intermediates generated by xanthine (Xa) - xanthine oxidase (XaOx) prior to air drying or by hydrogen peroxide solutions after air drying, enhanced C activation, possibly through oxidation of the cell lipid membrane. Several C inhibitors were tested for their effectiveness in blocking these systems. Pentosan polysulphate (PPS), an orally active agent, blocked C activation in the same concentration range of 1-1000 microg/ml as heparin, dextran sulphate, compstatin and fucoidan. PPS may have practical application as a C inhibitor.

Mapping the binding areas of human C-reactive protein for phosphorylcholine and polycationic compounds. Relationship between the two types of binding sites

We developed a fluorescence-based assay method for determining ligand binding activities of C-reactive protein (CRP) in solution. Using this method, we compared the phosphorylcholine (PC)- and polycation-based binding activities of human CRP. The PC-based binding required calcium, whereas a polycation (e.g. poly-l-lysine) was bound in the presence of either calcium or EDTA, the binding being stronger in the presence of EDTA. The published crystallographic structures of CRP and the CRP.PC complex show it to be a ring-shaped pentamer with a single PC-binding site per subunit facing the same direction. As expected from such a structure, binding affinity of a ligand increased tremendously when multiple PC residues were present on a macromolecular structure. In addition to PC-related structures, certain sugar phosphates (e.g. galactose 6-phosphate) are bound near the PC-binding site, and one of the sugar hydroxyl groups appears to interact with CRP. The best small ligands for the polycationic binding site were Lys-Lys and Lys4. Because of the presence of multiple Lys-Lys sequences, polylysines have tremendously enhanced affinity. Although PC inhibits both PC- and polycation-based binding, none of the amines that inhibit polylysine binding inhibits PC binding, suggesting that the PC and polycationic binding sites do not overlap.