Bao-Xi Qu

cPLA2α knockout mice exhibit abnormalities in the architecture and synapses of cortical neurons.

Cytosolic phospholipase A2α (cPLA2α) affects membrane fluidity and permeability by catalyzing the hydrolysis of membrane phospholipids. We hypothesize that cPLA2α deficiency induces rigidity and architectural changes in cell membranes, especially in large cortical neurons. These membrane changes are discernible using light and electron microscopy. Through careful comparison with wild-type counterparts, we observed significant morphological changes in cortical neurons of cPLA2α knockout mice. These changes included the following: (1) increased numbers of nucleoli and enlarged nuclei, (2) narrower spaces between the inner and outer nuclear membranes, (3) reduced numbers of nuclear pores and altered nuclear pore structure, and (4) morphological changes in synaptic clefts. These results further suggest that cPLA2α and its cleaved arachidonic acids play important roles in cortical neuronal maturation and in normal neurochemical processes.

Preservation and enumeration of endothelial progenitor and endothelial cells from peripheral blood for clinical trials

AIMS Endothelial progenitor cells (EPCs) are markers of vascular repair. Increased numbers of circulating endothelial cells (ECs) are associated with endothelial damage. MATERIALS & METHODS We enumerated EPC-EC by using Enrichment kit with addition of anti-human CD146-PE/Cy7 from peripheral blood mononuclear cell (PBMC) isolated either by red blood cell (RBC) lysing solution or by Ficoll centrifugation, and from fresh and preserved samples. PBMCs were quantified by flow cytometry. RESULTS RBC lysis yielded higher percentage of PBMC (p = 0.0242) and higher numbers of PBMC/ml (p = 0.0039) than Ficoll. Absolute numbers of CD34(+)CD133(+)VEGFR2(+) and CD146(+)CD34(+)VEGFR2(+) were higher (p = 0.0117 for both), when isolated by RBC lysis than by Ficoll, when no difference in other subsets was found. Cryopreservation at -160°C and -80°C and short-term preservation at room temperature decreased EPC-EC. CONCLUSIONS Our data support use of fresh samples and isolation of PBMC from human blood by RBC lysis for enumeration of EPC and EC.

Higher exosomal phosphorylated tau and total tau among veterans with combat-related repetitive chronic mild traumatic brain injury

ABSTRACT Objective: The objective of the study is to measure plasma and exosomal levels of tau, phosphorylated tau (p-tau), and amyloid beta (Aβ) in Veterans with historical mild traumatic brain injury (mTBI) and chronic neuropsychological symptoms. Methods: Tau, p-tau, Aβ40, and Aβ42 were measured by ultrasensitive immunoassay in plasma and exosomes from 195 Veterans enrolled in the Chronic Effects of Neurotrauma Consortium Multicenter Observational Study. Protein biomarkers were compared among groups with and without mTBI with loss of consciousness (LOC) or post-traumatic amnesia (PTA), and also in those with and without repetitive (≥3) mTBI (rTBI) compared to those with 0 (TBI-neg) and 1–2 mTBI. Results: There were no differences in measures of plasma and exosomal protein levels among mTBI with LOC or PTA, mTBI with alteration of consciousness only or TBI-neg. Exosomal tau and exosomal p-tau were elevated in rTBI compared to those with 2 or fewer mTBIs and TBI-neg (p < 0.05). Elevations of exosomal tau and p-tau significantly correlated with post-traumatic and post-concussive symptoms, with exosomal tau also relating specifically to cognitive, affective, and somatic post-concussive symptoms (p < 0.05). Conclusion: rTBI is associated with elevations of exosomal p-tau and exosomal tau, suggesting that blood-based exosomes may provide a peripheral source of informative, centrally derived biomarkers in remote mTBI and that rTBI may contribute to chronic neuropsychological symptoms.

Heterozygous knockout of cytosolic phospholipase A2α attenuates Alzheimer’s disease pathology in APP/PS1 transgenic mice

Cytosolic phospholipase A2α (cPLA2α) is a key enzyme in regulation of inflammation process and neuromembrane homeostasis, both of which are critical in pathogenesis of Alzheimers diseases. By hybride APP/PS1 Tg-AD mice with cPLA2α knockout mice, three lines of APP/PS1 Tg-AD mice were produced with genotypes of cPLA2α+/+, cPLA2α+/- and cPLA2α-/-. Compared to cPLA2α+/+ Tg-AD mice, the amyloid plaque formation was significantly downregulated in the brain of cPLA2α+/- Tg-AD mice, but not in cPLA2α-/- Tg-AD mice. The reactive gliosis were also significantly downregulated in both cPLA2α+/- and cPLA2α-/- Tg-AD mouse lines. The paradoxical effects of cPLA2α on the amyloid plaques reveal a complex role of cPLA2α in pathogenesis of AD and could be a potential target for prevention and treatment of AD.

Biomarkers of Vascular Integrity in Traumatic Brain Injury and Correlation with Cerebrovascular Reactivity

Objective: Several plasma proteins, such as Angiopoietins (Ang), Tumor Necrosis Factor (TNF), Serum Amyloid A (SAA), Soluble Intercellular Adhesion Molecule (sICAM-1), Von Willebrand Factor (vWF), and Tie2, have been implicated as potential biomarkers of vascular integrity and angiogenesis in traumatic brain and vascular injuries (TBI and TVI). Our goal is to test the hypothesis that (1) plasma biomarkers of vascular integrity and angiogenesis can assess TVI during chronic TBI; (2) Cerebrovascular Reactivity (CVR) may be a sensitive biomarker in chronic TBI and TVI and may correlate with the plasma biomarkers. Design: Plasma levels of 18 proteins were measured using high sensitivity electro-chemiluminescent sandwich immunoassays (Meso Scale Discoveries, LLC). Subjects were 23 patients with chronic TBI and persistent post-concussive symptoms (PCS, TBI-Sx), 9 chronic TBI patients without PCS (recovered TBIs or TBI-Rec), and 21 healthy controls (HC). TVI was assessed using MRI by measuring CVR-CO2 by assessing the BOLD response to hypercapnia. All subjects underwent MRI with hypercapnia challenge. Nominal a=0.05 was judged to be statistically significant. Results: Plasma concentration of Ang-1 was decreased in patients with chronic TBI with symptoms (TBI-Sx) compared to HC or TBI-Rec (p<0.05), as was the ratio of Ang-1/Ang-2 (p<0.05). SAA was decreased in TBI-Rec patients compared to the TBI-Sx group (P<0.01). CVR-CO2 was decreased in TBI-Sx group compared to HC (P<0.05). Baseline CVR-CO2 correlated with plasma levels of VEGF, VEGF-C, and P-selectin in all TBI patients, but not in HC group. Conclusions: A panel of plasma biomarkers (Ang-1/Ang-2, SAA, VEGF, P-selectin, and vWF) and assessment of CVR may be useful as predictive biomarkers for therapies designed to improve cerebrovascular function after TBI.