MicroCRP: a highly sensitive CRP method applied in the monitoring of renal allograft recipients

Analytical and Clinical Validation of a Time-resolved Immunofluorometric Assay (TR-IFMA) for Canine C-reactive Protein in Serum

A time-resolved immunofluorometric assay (TR-IFMA) was developed for the determination of C-reactive protein (CRP) in canine serum. CRP was isolated from canine acute-phase serum by affinity chromatography on agarose coupled with phosphorylethanolamine. This isolated dog CRP was used as standard to calibrate the assay. Intra-assay and inter-assay coefficients of variation were in the ranges 5.3-7.1% and 4.8-13.3%, respectively. Accuracy, evaluated by adding 2 and 10 microg/ml of CRP to serum samples, provided recoveries of 99.9% and 106.8%. High correlation was found between CRP measurements by TR-IFMA and a by commercial enzyme-linked immunosorbent assay (R2 = 0.98). The limit of detection for the TR-IFMA method was 0.000067 microg/ml and the measurement of CRP in serial dilutions of acute-phase dog sera generated curves with the same slope as the one constructed with purified CRP. The TR-IFMA provides a precise, accurate and highly sensitive assay for CRP determination in dog samples. CRP levels in dogs with different diseases ranged between 10.2 and 210.7 microg/ml and were significantly higher than those observed in healthy dogs (< 7.1 microg/ml).

Serum high sensitivity C-reactive protein is associated with carotid intima-media thickness in type 2 diabetes

BACKGROUND

High sensitivity C-reactive protein (hsCRP) is more sensitive than standard C-reactive protein (CRP) assay in evaluating the risk of coronary heart disease and other atherosclerotic events. By this time, there are several reports that type 2 diabetic subjects have higher serum levels of hsCRP than those of non-diabetic subjects. However, there are few reports about factors which have influence upon the level of serum hsCRP in type 2 diabetic subjects. We had evaluated the association of serum hsCRP level with risk factors of cardiovascular diseases and carotid intima-media thickness (IMT) in type 2 diabetic subjects.

METHODS

One hundred and five patients (59 men and 46 women) with type 2 diabetes were recruited. Subjects with severe cardiovascular diseases were excluded. All subjects were undergone carotid ultrasonography for evaluation of carotid IMT. Serum hsCRP concentrations were measured.

RESULTS

Serum hsCRP level was correlated with mean left IMT (r = 0.366, P = 0.003), maximal left IMT (r = 0.370, P = 0.002), mean right IMT (r = 0.281, P = 0.023) and maximal right IMT (r = 0.370, P = 0.002), body mass index (r = 0.377, P < 0.001), waist circumference (r = 0.342, P < 0.001), waist-hip ratio (r = 0.229, P = 0.020), serum total cholesterol (r = 0.202, P = 0.024), serum triglyceride (r = 0.292, P = 0.022) and serum low-density lipoprotein (r = 0.133, P = 0.044).

CONCLUSION

Our result shows that serum hsCRP level is correlated with carotid IMT and the risk factors of cardiovascular diseases and may be useful to predict accelerated atherosclerotic process in type 2 diabetic subjects.

Plasma C-reactive protein as a marker of cardiac allograft vasculopathy in heart transplant recipients

OBJECTIVES

This study was initiated to determine whether heart transplant recipients (HTRs) with cardiac allograft vasculopathy (CAV) have increased levels of high-sensitivity C-reactive protein (hsCRP) and to examine whether an increase in hsCRP after heart transplantation predicts the development of CAV. Furthermore, the effect of pravastatin on plasma levels of hsCRP in HTRs was investigated.

BACKGROUND

The relationship between CAV and hsCRP, as well as the effect of statins on hsCRP in HTRs, has not been well established.

METHODS

On referral for their annual angiographic control study, 150 consecutive HTRs (mean 6.5 years since transplantation) were included. Plasma levels of hsCRP were measured before angiography and compared with patients with (n = 52) and without (n = 98) CAV. In 49 of these patients, we additionally analyzed hsCRP in blood samples stored from their six-month visit after the transplantation procedure. Furthermore, in a randomized, crossover study, hsCRP was analyzed in 17 male HTRs before and after six weeks of treatment with 20 mg pravastatin.

RESULTS

Median levels of CRP were elevated among patients with CAV compared with those with normal angiograms [3.86 (1.78 to 7.00) vs. 1.08 (0.72 to 2.13) mg/l, p < 0.001]. Prospectively evaluated hsCRP levels from six months to follow-up were significantly higher among those who developed CAV compared with those with normal angiograms [+2.76 (1.56 to 5.00) vs. +0.07 (-0.57 to 0.41) mg/l, p < 0.001]. On multivariate analysis, the increase in hsCRP was the only significant predictor of CAV. Six weeks of treatment with pravastatin significantly reduced hsCRP levels by 25%, without any relation to changes in lipid values.

CONCLUSIONS

Elevated plasma levels of CRP are associated with angiographic evidence of CAV, and the increase in hsCRP is a strong predictor of development of CAV. Statin treatment reduces levels of hsCRP and should be used in HTRs, regardless of their lipid levels.

Double blind, randomized study of estradiol replacement therapy on markers of inflammation, coagulation and fibrinolysis

Estrogen replacement therapy (ERT) has been found to be associated with increased cardiovascular risk in the first year after initiation of ERT. We compared the effects of oral and transdermal estradiol (E2) replacement therapy on markers of inflammation, coagulation and fibrinolysis in a randomized double-blind trial. Forty-three healthy women were randomized 6 weeks after surgically induced menopause to receive treatment with either oral or transdermal E2 over a period of 28 weeks. At baseline and after 28 weeks, levels of serum lipids and lipoproteins, and markers of coagulation, fibrinolysis and inflammation were determined. Among fibrinolytic parameters, oral E2 shortened euglobulin clot lysis time (P<0.05) and reduced tissue type plasminogen activator antigen (P=0.01) and plasminogen activator inhibitor activity (P<0.05). Among coagulation parameters, both routes of E2 replacement decreased fibrinogen levels (P=0.002 for oral and P=0.007 for transdermal E2). Oral E2 resulted in an increase in C-reactive protein (CRP) from 2.15 (0.71-4.05) to 3.41 (1.12-5.92) mg/l (P=0.04), while transdermal E2 showed no effect. Levels of serum amyloid A (SAA), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) did not change significantly after oral and transdermal E2. Oral E2 significantly improved the lipid profile, while transdermal E2 had a less pronounced effect. Both oral and transdermal E2 significantly reduced fasting glucose. Oral E2 was associated with a pro-inflammatory response, but at the same time improved fibrinolytic capacity, showed no pro-coagulatory effects, and acted beneficially on lipids and lipoproteins. There was no influence of transdermal E2 on markers of coagulation activation, fibrinolysis and inflammation, but it decreased fibrinogen levels significantly. Further studies are needed to explore the clinical relevance of these observations.

Serum C-reactive protein in pediatric kidney and liver transplant patients

The clinical manifestations of different complications after organ transplantation (Tx) are often vague, and simple laboratory tests for early diagnosis would be valuable. In this work we retrospectively analyzed our data on the daily measurements of serum C-reactive protein (CRP) in 132 children after 63 liver and 83 kidney Txs. A total of 3,886 CRP measurements were performed and 353 episodes of elevated CRP were recorded. One-third of these were regarded as a response to surgery. The CRP level normalized within 5-10 days post-operatively in patients who had a favorable outcome, but in patients with a poor outcome CRP tended to remain elevated. Half of the CRP elevations were associated with complications such as acute rejection, infection or thrombotic events. An elevated serum CRP level was found in 68% of the rejection episodes, in 88% of the bacterial infections, and in 73% of the viral infections. The most significant elevations were associated with bacterial infection. In nine of 11 vascular complications, an elevation of CRP was also recorded. Serum CRP responded to rejection therapy in 86% of the episodes. The initial CRP level did not predict steroid-resistant rejection. CRP seemed to be a more sensitive marker than fever or white blood cell (WBC) count in all complications. We conclude that the daily measurement of serum CRP is a simple and fairly sensitive, but non-specific, method for detecting rejection and infectious complications after pediatric liver and kidney Tx.

An increase in myeloid-related protein serum levels precedes acute renal allograft rejection

Upon interaction with activated endothelium, monocytes and neutrophils form complexes of myeloid-related protein 8 (MRP8) (S100A8) and MRP14 (S100A9), two members of the calcium-binding S100 family that are secreted during transendothelial migration. In a pilot study of 20 renal transplant recipients and a validation study of 36 renal transplant recipients, MRP8/14 serum levels were measured with an enzyme-linked immunosorbent assay for 28 d, associated with C-reactive protein and creatinine serum levels, and grouped according to biopsy-proven acute rejection. Serum levels of MRP8/14 but not C-reactive protein were significantly increased for several days during the first 2 wk for the acute rejection groups in both studies (P < 0.005, on day 6 after transplantation). As determined by using receiver operating characteristic curves, the optimal cutoff for 100% specificity and high sensitivity (67%) for acute rejection on day 6 after transplantation was calculated to be 4.2 microg/ml for MRP8/14 in the pilot study; this value was confirmed in the validation study. Positive MRP8/14 serum levels preceded acute rejection episodes by a median of 5 d. A 3-d course of intravenous methylprednisolone therapy reduced prerejection MRP8/14 serum levels from 5.7 microg/ml to 3.3 microg/ml (P < 0.05). All MRP8/14 serum levels were below the cutoff during urinary tract infections, delayed graft function, or cytomegalovirus infections, and these values did not differ significantly from control values. It is concluded that the MRP8/14 complex is a very early serum marker suitable for monitoring of acute rejection with high sensitivity and specificity.