Influence of kidney function and CSF/serum albumin ratio on plasma Aß42 and Aß40 levels measured on a fully automated platform in patients with Alzheimer's disease.

INTRODUCTION: Alzheimer's disease  (AD) is characterized by decreased cerebrospinal fluid (CSF) Aß42 and Aß42/Aß40 ratio. Aß peptides can now be measured also in plasma and are promising peripheral biomarkers for AD. We evaluated the relationships of plasma Aß species with their CSF counterparts, kidney function, and serum/CSF albumin ratio (Q-Alb) in AD patients. MATERIALS AND METHODS: We measured plasma Aß42 and Aß40, as well as CSF AD biomarkers, with the fully automated Lumipulse platform in a cohort of N = 30 patients with clinical and neurochemical diagnosis of AD. RESULTS: The two plasma Aß peptides correlated strongly with each other (r = 0.7449), as did the corresponding CSF biomarkers (r = 0.7670). On the contrary, the positive correlations of plasma Aß42, Aß40, and Aß42/Aß40 ratio with their CSF counterparts and the negative correlation of plasma Aß42/Aß40 ratio with CSF P-tau181 were not statistically significant. Plasma levels of both Aß species negatively correlated with estimated glomerular filtration rate (eGFR) (Aß42: r = -0.4138; Aß40: r = -0.6015), but plasma Aß42/Aß40 ratio did not. Q-Alb did not correlate with any plasma Aß parameter. DISCUSSION: Plasma Aß42 and Aß40 are critically influenced by kidney function; however, their ratio is advantageously spared from this effect. The lack of significant correlations between plasma Aß species and their CSF counterparts is probably mainly due to small sample size and inclusion of only Aß + individuals. Q-Alb is not a major determinant of plasma Aß concentrations, highlighting the uncertainties about mechanisms of Aß transfer between CNS and periphery.

A Novel Automated Chemiluminescence Method for Detecting Cerebrospinal Fluid Amyloid-Beta 1-42 and 1-40, Total Tau and Phosphorylated-Tau: Implications for Improving Diagnostic Performance in Alzheimer's Disease.

Recently, a fully automated instrument for the detection of the Cerebrospinal Fluid (CSF) biomarker for Alzheimer's disease (AD) (low concentration of Amyloid-beta 42 (Aß42), high concentration of total tau (T-tau) and Phosphorylated-tau (P-tau181)), has been implemented, namely CLEIA. We conducted a comparative analysis between ELISA and CLEIA methods in order to evaluate the analytical precision and the diagnostic performance of the novel CLEIA system on 111 CSF samples. Results confirmed a robust correlation between ELISA and CLEIA methods, with an improvement of the accuracy with the new CLEIA methodology in the detection of the single biomarkers and in their ratio values. For Aß42 regression analysis with Passing−Bablok showed a Pearson correlation coefficient r = 0.867 (0.8120; 0.907% 95% CI p < 0.0001), T-tau analysis: r = 0.968 (0.954; 0.978% 95% CI p < 0.0001) and P-tau181: r = 0.946 (0.922; 0.962 5% 95% CI p < 0.0001). The overall ROC AUC comparison between ROC in ELISA and ROC in CLEIA confirmed a more accurate ROC AUC with the new automatic method: T-tau AUC ELISA = 0.94 (95% CI 0.89; 0.99 p < 0.0001) vs. AUC CLEIA = 0.95 (95% CI 0.89; 1.00 p < 0.0001), and P-tau181 AUC ELISA = 0.91 (95% CI 0.85; 0.98 p < 0.0001) vs. AUC CLEIA = 0.98 (95% CI 0.95; 1.00 p < 0.0001). The performance of the new CLEIA method in automation is comparable and, for tau and P-tau181, even better, as compared with standard ELISA. Hopefully, in the future, automation could be useful in clinical diagnosis and also in the context of clinical studies.

Prothrombin induced by vitamin K absence or antagonist-II and alpha foetoprotein to predict development of hepatocellular carcinoma in Caucasian patients with hepatitis C-related cirrhosis treated with direct-acting antiviral agents.

BACKGROUND: Prothrombin induced by vitamin K absence or antagonist-II (PIVKA-II) and alpha fetoprotein (AFP) are biomarkers for hepatocellular carcinoma (HCC). However, their performance in patients with cirrhosis related to hepatitis C virus (HCV) treated with direct-acting antiviral agents (DAA) is unknown. AIM: To evaluate PIVKA-II and AFP as HCC predictors in DAA-treated patients with HCV-related cirrhosis METHODS: In this single centre study, patients with cirrhosis from chronic HCV infection and with a sustained virological response (SVR) to DAA were tested for PIVKA-II and AFP (Fujirebio, Japan) at the start of DAA treatment (baseline), end of treatment (EOT) and at HCC diagnosis. RESULTS: We included 400 patients with mean age 65 (24-92); 56% were men. From baseline to EOT, PIVKA-II did not change (35 vs 35 mAU/mL, P = 0.43) while AFP significantly decreased (12 vs 6 ng/mL, P < 0.0001). After 52 (3-66) months from baseline, 34 (8.5%) patients developed de novo HCC; median AFP 9 (2-12 868) ng/mL and PIVKA-II 80 (22-1813) mAU/mL. EOT-PIVKA-II (HR 3.05, P < 0.0001) and AFP (HR 2.77, P = 0.001) independently predicted HCC together with diabetes (HR 6.12, P < 0.001) and GGT (HR 1.01, P = 0.03). The 4-year cumulative probability of HCC was 24% vs 2% in patients with EOT-PIVKA-II > or ≤41 mAU/mL (P < 0.0001), and 26% vs 9% for EOT-AFP > or ≤15 ng/mL (P = 0.02). By combining EOT-PIVKA-II and AFP, the 4-year probabilities of HCC were 3% in patients testing negative for both markers, 18% in patients positive for both, and 38% in patients positive for at least one (P < 0.0001). CONCLUSIONS: In patients with HCV-related cirrhosis treated with DAA, PIVKA-II and AFP independently predicted HCC, while their combination improved risk stratification.