Human PON1, a biomarker of risk of disease and exposure.

Human paraoxonase 1 (PON1) is a high-density lipoprotein (HDL)-associated serum enzyme that exhibits a broad substrate specificity. In addition to protecting against exposure to some organophosphorus (OP) pesticides by hydrolyzing their toxic oxon metabolites, PON1 is important in protecting against vascular disease by metabolizing oxidized lipids. Recently, PON1 has also been shown to play a role in inactivating the quorum sensing factor N-(3-oxododecanoyl)-l-homoserine lactone (3OC12-HSL) of Pseudomonas aeruginosa. Native, untagged engineered recombinant human PON1 (rHuPON1) expressed in Escherichia coli and purified by conventional column chromatographic purification is stable, active, and capable of protecting PON1 knockout mice (PON1(-/-)) from exposure to high levels of the OP compound diazoxon. The bacterially derived rHuPON1 can be produced in large quantities and lacks the glycosylation of eukaryotic systems that can produce immunogenic complications when inappropriately glycosylated recombinant proteins are used as therapeutics. Previous studies have shown that the determination of PON1 status, which reveals both PON1(192) functional genotype and serum enzyme activity level, is required for a meaningful evaluation of PON1's role in risk of disease or exposure. We have developed a new two-substrate assay/analysis protocol that provides PON1 status without use of toxic OP substrates, allowing for use of this protocol in non-specialized laboratories. Factors were also determined for inter-converting rates of hydrolysis of different substrates. PON1 status also plays an important role in revealing changes in HDL-associated PON1 activities in male patients with Parkinson disease (PD). Immunolocalization studies of PONs 1, 2 and 3 in nearly all mouse tissues suggest that the functions of PONs 1 and 3 extend beyond the plasma and the HDL particle.

Nonconcordance between subclinical atherosclerosis and the calculated Framingham risk score in HIV-infected patients: relationships with serum markers of oxidation and inflammation.

OBJECTIVES: HIV-infected patients show an increased cardiovascular disease (CVD) risk resulting, essentially, from metabolic disturbances related to chronic infection and antiretroviral treatments. The aims of this study were: (1) to evaluate the agreement between the CVD risk estimated using the Framingham risk score (FRS) and the observed presence of subclinical atherosclerosis in HIV-infected patients; (2) to investigate the relationships between CVD and plasma biomarkers of oxidation and inflammation. METHODS: Atherosclerosis was evaluated in 187 HIV-infected patients by measuring the carotid intima-media thickness (CIMT). CVD risk was estimated using the FRS. We also measured the circulating levels of interleukin-6, monocyte chemoattractant protein-1 (MCP-1) and oxidized low-density lipoprotein (LDL), and paraoxonase-1 activity and concentration. RESULTS: There was a weak, albeit statistically significant, agreement between FRS and CIMT (kappa=0.229, P<0.001). A high proportion of patients with an estimated low risk had subclinical atherosclerosis (n=66; 56.4%). In a multivariate analysis, the presence of subclinical atherosclerosis in this subgroup of patients was associated with age [odds ratio (OR) 1.285; 95% confidence interval (CI) 1.084-1.524; P=0.004], body mass index (OR 0.799; 95% CI 0.642-0.994; P=0.044), MCP-1 (OR 1.027; 95% CI 1.004-1.050; P=0.020) and oxidized LDL (OR 1.026; 95% CI 1.001-1.051; P=0.041). CONCLUSION: FRS underestimated the presence of subclinical atherosclerosis in HIV-infected patients. The increased CVD risk was related, in part, to the chronic oxidative stress and inflammatory status associated with this patient population.

Pitfalls in measuring high-density lipoprotein cholesterol concentrations in HIV-infected patients.

OBJECTIVES: HIV infection and its treatment are associated with dyslipidaemia and increased risk of cardiovascular disease. Accurate high-density lipoprotein (HDL) cholesterol values are necessary for the management of these abnormalities, but current methods have not been properly assessed in these patients. The aim of this study was to assess in HIV-infected patients the consistency and accuracy of a synthetic polymer/detergent homogeneous assay used to measure HDL cholesterol concentrations and to evaluate the impact of storage. METHODS: HDL cholesterol was measured using a synthetic polymer/detergent homogeneous method in samples from HIV-infected patients and healthy subjects for each of the storage regimens: baseline, after 1 week at 4 degrees C, and after 12 months at -80 degrees C. The ultracentrifugation and precipitation assays were used for comparison. RESULTS: Three out of every 20 samples from HIV-infected patients had discrepant HDL cholesterol values with respect to the ultracentrifugation method. Overestimation was associated with high C-reactive protein concentrations and underestimation with plasma gamma-globulin concentrations, an effect that was amplified by any of the storage conditions tested. CONCLUSIONS: Caution is needed when using the synthetic polymer/detergent homogeneous method for direct measurement of HDL cholesterol concentrations in HIV-infected patients. This assay is of limited use in clinical trials in which frozen samples are analysed.

[Is there a relationship between cystatin C and inflammatory status, oxidative stress and other cardiovascular risk factors in non-diabetic patients with chronic kidney disease?]. / ¿Existe relación entre los niveles de cistatina C y el estado inflamatorio, el estrés oxidativo y otros factores de riesgo cardiovascular en pacientes no diabéticos con enfermedad renal crónica?

UNLABELLED: Cystatin C is a marker of renal function and a major cardiovascular risk factor. In the general population, cystatin C appears to be influenced by factors other than renal function alone. However, information for serum cystatin C levels in chronic kidney disease (CKD) is lacking. METHODS: We studied 52 nondiabetic patients (38 men, mean age 49 years) with CKD stage 3 (22), 4 (25) or 5 (5) who had measurements of serum cystatin C levels, estimated glomerular filtration rate (MDRD), inflammatory (C-reactive protein, interleukin-6 and fibrinogen), and oxidative markers (anti-oxidized LDL antibodies, serum paraoxonase-1 activity and concentration), left ventricular mass index by echocardiography and other cardiovascular risk factors. RESULTS: Mean cystatin C levels were 2.35 +/- 0.9 mg/l. Cystatin C was positively correlated with creatinine serum levels, estimated glomerular filtration rate, PTH levels and negatively with anti-oxidized LDL antibodies. On the other hand, cystatin C was not related to inflammatory markers, serum paraoxonase-1 activity and concentration, proteinuria, HDL or LDL cholesterol, serum triglycerides, left ventricular mass index or demographic factors such as age, body mass index and blood pressure. After adjustment for PTH levels and anti- oxidized LDL antibodies, only estimated glomerular filtration rate was independently related serum cystatin C levels (beta = -0.500, p = 0.001). CONCLUSION: In nondiabetic patients with CKD, cystatin C is closely related to the degree of renal dysfunction. In contrast, inflammatory state, oxidative stress, left ventricular mass index and other cardiovascular risk factors are not related to cystatin C levels in this population.

¿Existe relación entre los niveles de cistatina C y el estado inflamatorio, el estrés oxidativo y otros factores de riesgo cardiovascular en pacientes no diabéticos con enfermedad renal crónica? / No disponible

La cistatina C es un marcador de función renal y predictor de morbimortalidad cardiovascular. En la población general, la cistatina C está condicionada por diversos factores independientes de la función renal, pero es poco conocido qué factores se relacionan con esta proteína en fases avanzadas de la Enfermedad Renal Crónica (ERC). Pacientes y métodos: se estudian 52pacientes no diabéticos (38 hombres, edad media 49 años) en diferentes estadios de ERC (22 en estadio 3, 25 en estadio 4 y 5en estadio 5), en los que se determinaron los niveles de cistatina C, filtrado glomerular estimado (MDRD), estado inflamatorio (PCR, IL-6 y fibrinógeno), estrés oxidativo (anticuerpos antiLDL oxidada, actividad y concentración de paraoxonasa-1[PON-1]), masa ventricular izquierda (ecocardiograma) y otros factores de riesgo cardiovascular. Resultados: los niveles medios de cistatina C fueron de 2,35 ± 0,9 mg/l. La cistatina C se correlacionó con los niveles séricos de creatinina, filtrado glomerular estimado, niveles de PTH, y negativamente con los anticuerpos anti-LDL oxidada. Por el contrario, no se encontró ninguna relación entre esta proteína y los marcadores de inflamación, la actividad y concentración de PON, los niveles de colesterol y sustracciones, triglicéridos, proteinuria, masa ventricular izquierda ni parámetros demográficos como edad, Índice de Masa Corporal (IMC) o tensión arterial. En un análisis de regresión múltiple, después de ajustar por los niveles de PTH y anticuerpos anti-LDL oxidada, sólo el filtrado glomerular estimado se relacionó independientemente con los niveles de cistatina C (Beta=-0.500, p=0.001). Conclusión: en pacientes no diabéticos con ERC prediálisis, los niveles de cistatina C están estrechamente relacionados con el grado de disfunción renal. El estado inflamatorio, el estrés oxidativo, la masa cardíaca y otros factores de riesgo cardiovascular no son determinantes de los niveles de cistatina C en fases avanzadas de la ERC. Palabras clave: Cistatina C, inflamación, estrés oxidativo, paraoxonasa-1, factores de riesgo, enfermedad renal crónica (AU)

Cystatin C is a marker of renal function and a major cardiovascular risk factor. In the general population, cystatin C appears to be influenced by factors other than renal function alone. However, information for serum cystatin C levels in chronic kidney disease (CKD) is lacking. Methods: We studied 52 non diabetic patients (38 men, mean age 49 years) with CKD stage 3 (22), 4 (25) or 5 (5)who had measurements of serum cystatin C levels, estimated glomerular filtration rate (MDRD), inflammatory(C-reactive protein, interleukin-6 and fibrinogen), and oxidative markers (anti-oxidized LDL antibodies, serumparaoxonase-1 activity and concentration), left ventricular mass index by echocardiography and other cardiovascular risk factors. Results: Mean cystatin C levels were 2.35 ± 0.9mg/l. Cystatin C was positively correlated with creatinine serum levels, estimated glomerular filtration rate, PTH levels and negatively with anti-oxidized LDL antibodies. On the other hand, cystatin C was not related to inflammatory markers, serum paraoxonase-1 activity and concentration, proteinuria, HDL or LDL cholesterol, serum triglycerides, left ventricular mass index or demographic factors such as age, body mass index and blood pressure. After adjustment for PTH levels and anti- oxidized LDL antibodies, only estimated glomerular filtration rate was independently related serum cystatin C levels (â = -0.500, p= 0.001). Conclusion: In non diabetic patients with CKD, cystatin C is closely related to the degree of renal dysfunction. In contrast, inflammatory state, oxidative stress, left ventricular mass index and other cardiovascular risk factors are not related to cystatin C levels in this population (..) (AU)