Storage time affects the level and diagnostic efficacy of plasma biomarkers for neurodegenerative diseases

Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results.

miR-93-5p Transferred by Exosomes Promotes the Proliferation of Esophageal Cancer Cells via Intercellular Communication by Targeting PTEN

Objective To investigate the relationship between plasma miR-93-5p and the risk of esophageal cancer, as well as the influence of miR-93-5p on the biological function of esophageal cancer cells,exerted through exosomes.Methods The expression of plasma miR-93-5p in esophageal cancer patients and healthy controls was analysed by real-time quantitative PCR. The influence of miR-93-5p on the risk and prognosis of esophageal carcinoma was analyzed by conditional logistic regression and survival analysis. The effect of miR-93-5p on the biological function of recipient cells was investigated by establishing an in vitro donor cell co-culture model. The target gene of miR-93-5p was validated by luciferase reporter assay and Western Blotting.Results Upregulation of plasma miR-93-5p expression significantly increases the risk of esophageal cancer and is associated with poor prognosis. miR-93-5p transferred by exosomes promotes the proliferation of recipient esophageal cancer cells and affects the expression of PTEN and its downstream proteins p21 and cyclin D1.Conclusion Our study provides a reference for the identification of biomarkers for the diagnosis and prognosis of esophageal cancer.

Ultrasensitive assays for detection of plasma tau and phosphorylated tau 181 in Alzheimer's disease:a systematic review and meta-analysis

A lack of convenient and reliable biomarkers for diagnosis and prognosis is a common challenge for neurodegenerative diseases such as Alzheimer's disease(AD).Recent advancement in ultrasensitive protein assays has allowed the quantification of tau and phosphorylated tau proteins in peripheral plasma.Here we identified 66 eligible studies reporting quantification of plasma tau and phosphorylated tau 181(ptau181)using four ultrasensitive methods.Meta-analysis of these studies confirmed that the AD patients had significantly higher plasma tau and ptau181 levels compared with controls,and that the plasma tau and ptau181 could predict AD with high-accuracy area under curve of the Receiver Operating Characteristic Therefore,plasma tau and plasma ptau181 can be considered as biomarkers for AD diagnosis.

Plasma glial fibrillary acidic protein and neurofilament light chain for the diagnostic and prognostic evaluation of frontotemporal dementia

Background:Astrocytes play an essential role in neuroinflammation and are involved in the pathogenesis of neurodenegerative diseases.Studies of glial fibrillary acidic protein(GFAP),an astrocytic damage marker,may help advance our understanding of different neurodegenerative diseases.In this study,we investigated the diagnostic performance of plasma GFAP(pGFAP),plasma neurofilament light chain(pNfL)and their combination for frontotemporal dementia(FTD)and Alzheimer's disease(AD)and their clinical utility in predicting disease progression.Methods:pGFAP and pNfL concentrations were measured in 72 FTD,56 AD and 83 cognitively normal(CN)participants using the Single Molecule Array technology.Of the 211 participants,199 underwent cerebrospinal(CSF)analysis and 122 had magnetic resonance imaging.We compared cross-sectional biomarker levels between groups,studied their diagnostic performance and assessed correlation between CSF biomarkers,cognitive performance and cortical thickness.The prognostic performance was investigated,analyzing cognitive decline through group comparisons by tertile.Results:Unlike pNfL,which was increased similarly in both clinical groups,pGFAP was increased in FTD but lower than in AD(all P<0.01).Combination of both plasma markers improved the diagnostic performance to discriminate FTD from AD(area under the curve[AUC]:combination 0.78;pGFAP 0.7;pNfL 0.61,all P<0.05).In FTD,pGFAP correlated with cognition,CSF and plasma NfL,and cortical thickness(all P<0.05).The higher tertile of pGFAP was associated with greater change in MMSE score and poor cognitive outcome during follow-up both in FTD(1.40 points annually,hazard ratio[HR]3.82,P<0.005)and in AD(1.20 points annually,HR 2.26,P<0.005).Conclusions:pGFAP and pNfL levels differ in FTD and AD;and their combination is useful for distinguishing between the two diseases.pGFAP could also be used to track disease severity and predict greater cognitive decline during follow-up in patients with FTD.

Plasma levels of tissue inhibitor of matrix metalloproteinase-1 correlate with diagnosis and prognosis of glioma patients

Background There is no validated blood biomarker available for glioma management. Invasive growth is the key feature of glioma. We assessed the clinical usefulness of plasma tissue inhibitor of metalloproteinase 1 （TIMP-1）, which has less molecular weight than metalloproteinases, as a potential blood biomarker for glioma. Methods A total of 285 patients and 59 normal subjects were studied. Plasma concentration of TIMP-1 was measured with enzyme-linked immunosorbent assay. Plasma TIMP-1 was compared between normal and glioma patients, between patients with different pathological grades, and between patients with different prognoses. Longitudinal changes in plasma TIMP-1 during treatment were also evaluated. Plasma matrix metalloproteinase （MMP）-9 level was also assayed and its clinical usefulness was compared with that of TIMP-1. Results Plasma TIMP-1 and MMP-9 were both increased in glioma patients compared with normal controls （TIMP-1： P 〈0.001; MMP-9： P=0.007）. Plasma TIMP-1 increases with increased tumor grade. In Grade Ⅳ gliomas, plasma TIMP- 1 significantly increased after ＂successful removal＂ of the tumor （paired samples t-test, before operation vs. during chemotherapy without recurrence, t = -2.131, P=0.038）, but did not change significantly at the time of tumor recurrence （during chemotherapy without recurrence vs. after tumor recurrence, t = -0.652, P=-0.632）. High plasma TIMP-1 level correlated with better survival in Grade IV glioma patients （hazard ratio： 0.550, 95% CI： 0.101-1.000, P=0.036）. In Grade IV gliomas, patients with higher plasma TIMP-1 had significantly longer survival time than those with lower plasma TIMP-1 level （25.23 vs. 18.95 months, log-rank P=0.045）. Plasma MMP-9 did not show significant association with either the pathological grade or the prognosis of glioma patients. Conclusions Plasma TIMP-1 is associated with the diagnosis and prognosis of glioma patients. It appears to have better usefulness for guiding clinical decision making than plasma MMP-9. Further studies in an expanded patient population are needed to better define its clinical usefulness.