Quantifying cerebellum grey matter and white matter perfusion using pulsed arterial spin labeling.

To facilitate quantification of cerebellum cerebral blood flow (CBF), studies were performed to systematically optimize arterial spin labeling (ASL) parameters for measuring cerebellum perfusion, segment cerebellum to obtain separate CBF values for grey matter (GM) and white matter (WM), and compare FAIR ASST to PICORE. Cerebellum GM and WM CBF were measured with optimized ASL parameters using FAIR ASST and PICORE in five subjects. Influence of volume averaging in voxels on cerebellar grey and white matter boundaries was minimized by high-probability threshold masks. Cerebellar CBF values determined by FAIR ASST were 43.8 ± 5.1 mL/100 g/min for GM and 27.6 ± 4.5 mL/100 g/min for WM. Quantitative perfusion studies indicated that CBF in cerebellum GM is 1.6 times greater than that in cerebellum WM. Compared to PICORE, FAIR ASST produced similar CBF estimations but less subtraction error and lower temporal, spatial, and intersubject variability. These are important advantages for detecting group and/or condition differences in CBF values.

Advancing the high throughput identification of liver fibrosis protein signatures using multiplexed ion mobility spectrometry.

Rapid diagnosis of disease states using less invasive, safer, and more clinically acceptable approaches than presently employed is a crucial direction for the field of medicine. While MS-based proteomics approaches have attempted to meet these objectives, challenges such as the enormous dynamic range of protein concentrations in clinically relevant biofluid samples coupled with the need to address human biodiversity have slowed their employment. Herein, we report on the use of a new instrumental platform that addresses these challenges by coupling technical advances in rapid gas phase multiplexed ion mobility spectrometry separations with liquid chromatography and MS to dramatically increase measurement sensitivity and throughput, further enabling future high throughput MS-based clinical applications. An initial application of the liquid chromatography--ion mobility spectrometry-MS platform analyzing blood serum samples from 60 postliver transplant patients with recurrent fibrosis progression and 60 nontransplant patients illustrates its potential utility for disease characterization.

Anteroposterior perfusion heterogeneity in human hippocampus measured by arterial spin labeling MRI.

Measurements of blood flow in the human hippocampus are complicated by its relatively small size, unusual anatomy and patterns of blood supply. Only a handful of arterial spin labeling (ASL) MRI articles have reported regional cerebral blood flow (rCBF) values for the human hippocampus. Numerous reports have found heterogeneity in a number of other physiological and biochemical parameters along the longitudinal hippocampal axis. There is, however, only one ASL study of perfusion properties as a function of anteroposterior location in the hippocampus, reporting that rCBF is lower and the arterial transit time (ATT) is longer in the anterior hippocampus than in the posterior hippocampus of the rat brain. The purpose of this article was to measure ATT and rCBF in anterior, middle and posterior normal adult human hippocampus. To better distinguish anteroposterior perfusion heterogeneity in the hippocampus, a modified ASL method, called Orthogonally Positioned Tagging Imaging Method for Arterial Labeling with Flow-sensitive Alternating Inversion Recovery (OPTIMAL FAIR), was developed that provides high in-plane resolution with oblique coronal imaging slices perpendicular to the long axis of the hippocampus to minimize partial volume effects. Perfusion studies performed with this modified FAIR method at 3 T indicated that anterior, middle and posterior human hippocampus segments have unique transit time and rCBF values. Of these three longitudinal hippocampal regions, the middle hippocampus has the highest perfusion and the shortest transit time and the anterior hippocampus has the lowest perfusion and the longest transit time. Copyright © 2013 John Wiley & Sons, Ltd.

Quantitative proteomic analysis of HIV-1 infected CD4+ T cells reveals an early host response in important biological pathways: protein synthesis, cell proliferation, and T-cell activation.

Human immunodeficiency virus (HIV-1) depends upon host-encoded proteins to facilitate its replication while at the same time inhibiting critical components of innate and/or intrinsic immune response pathways. To characterize the host cell response on protein levels in CD4+ lymphoblastoid SUP-T1 cells after infection with HIV-1 strain LAI, we used mass spectrometry (MS)-based global quantitation with iTRAQ (isobaric tag for relative and absolute quantification). We found 266, 60 and 22 proteins differentially expressed (DE) (P-value ≤ 0.05) at 4, 8, and 20 hours post-infection (hpi), respectively, compared to time-matched mock-infected samples. The majority of changes in protein abundance occurred at an early stage of infection well before the de novo production of viral proteins. Functional analyses of these DE proteins showed enrichment in several biological pathways including protein synthesis, cell proliferation, and T-cell activation. Importantly, these early changes before the time of robust viral production have not been described before.

Morphine produces immunosuppressive effects in nonhuman primates at the proteomic and cellular levels.

Morphine has long been known to have immunosuppressive properties in vivo, but the molecular and immunologic changes induced by it are incompletely understood. To explore how these changes interact with lentiviral infections in vivo, animals from two nonhuman primate species (African green monkeys and pigtailed macaques) were provided morphine and studied using a systems biology approach. Biological specimens were obtained from multiple sources (e.g. lymph node, colon, cerebrospinal fluid, and peripheral blood) before and after the administration of morphine (titrated up to a maximum dose of 5 mg/kg over a period of 20 days). Cellular immune, plasma cytokine, and proteome changes were measured and morphine-induced changes in these parameters were assessed on an interorgan, interindividual, and interspecies basis. In both species, morphine was associated with decreased levels of Ki-67(+) T-cell activation but with only minimal changes in overall T-cell counts, neutrophil counts, and NK cell counts. Although changes in T-cell maturation were observed, these varied across the various tissue/fluid compartments studied. Proteomic analysis revealed a morphine-induced suppressive effect in lymph nodes, with decreased abundance of protein mediators involved in the functional categories of energy metabolism, signaling, and maintenance of cell structure. These findings have direct relevance for understanding the impact of heroin addiction and the opioids used to treat addiction as well as on the potential interplay between opioid abuse and the immunological response to an infective agent.

Proteome and computational analyses reveal new insights into the mechanisms of hepatitis C virus-mediated liver disease posttransplantation.

UNLABELLED: Liver transplant tissues offer the unique opportunity to model the longitudinal protein abundance changes occurring during hepatitis C virus (HCV)-associated liver disease progression in vivo. In this study, our goal was to identify molecular signatures, and potential key regulatory proteins, representative of the processes influencing early progression to fibrosis. We performed global protein profiling analyses on 24 liver biopsy specimens obtained from 15 HCV(+) liver transplant recipients at 6 and/or 12 months posttransplantation. Differentially regulated proteins associated with early progression to fibrosis were identified by analysis of the area under the receiver operating characteristic curve. Analysis of serum metabolites was performed on samples obtained from an independent cohort of 60 HCV(+) liver transplant patients. Computational modeling approaches were applied to identify potential key regulatory proteins of liver fibrogenesis. Among 4,324 proteins identified, 250 exhibited significant differential regulation in patients with rapidly progressive fibrosis. Patients with rapid fibrosis progression exhibited enrichment in differentially regulated proteins associated with various immune, hepatoprotective, and fibrogenic processes. The observed increase in proinflammatory activity and impairment in antioxidant defenses suggests that patients who develop significant liver injury experience elevated oxidative stresses. This was supported by an independent study demonstrating the altered abundance of oxidative stress-associated serum metabolites in patients who develop severe liver injury. Computational modeling approaches further highlight a potentially important link between HCV-associated oxidative stress and epigenetic regulatory mechanisms impacting on liver fibrogenesis. CONCLUSION: Our proteome and metabolome analyses provide new insights into the role for increased oxidative stress in the rapid fibrosis progression observed in HCV(+) liver transplant recipients. These findings may prove useful in prognostic applications for predicting early progression to fibrosis.

Improved quantification of brain perfusion using FAIR with active suppression of superior tagging (FAIR ASST).

PURPOSE: To address two problems for perfusion studies in the middle or inferior brain regions: (1) to reduce venous artifacts due to the intrinsic superior labeling of FAIR; (2) to alleviate the discrepancy of the existence of both superior and inferior boluses, but with only the inferior bolus having a temporally defined bolus width with Q2TIPs or QUIPSS. MATERIALS AND METHODS: Superior tagging suppression methods for FAIR with different combinations of pre- and postinversion superior saturation pulses were evaluated and compared with FAIR with Q2TIPS for producing perfusion maps of superior, middle, and inferior brain regions. RESULTS: One preinversion plus two postinversion superior saturation radio frequency pulses effectively suppressed the superior tagging of FAIR and sufficiently eliminated venous artifacts without negative effects, avoiding the overestimations of cerebral blood flow that can occur in FAIR. CONCLUSION: FAIR ASST improves FAIR with Q2TIPS and provides more reliable and accurate blood flow estimations for perfusion studies of middle and lower brain regions. FAIR ASST confers the advantages of asymmetric PASL techniques, such as PICORE, in which only the inferiorly labeled blood is used for perfusion quantification, to the symmetric PASL technique FAIR, while preserving the robustness of FAIR against MT effects.

Fas ligand-induced proinflammatory transcriptional responses in reconstructed human epidermis. Recruitment of the epidermal growth factor receptor and activation of MAP kinases.

Fas ligand (FasL) exerts potent proapoptotic and proinflammatory actions on epidermal keratinocytes and has been implicated in the pathogenesis of eczema, toxic epidermal necrolysis, and drug-induced skin eruptions. We used reconstructed human epidermis to investigate the mechanisms of FasL-induced inflammatory responses and their relationships with FasL-triggered caspase activity. Caspase activity was a potent antagonist of the pro-inflammatory gene expression triggered by FasL prior to the onset of cell death. Furthermore, we found that FasL-stimulated autocrine production of epidermal growth factor receptor (EGFR) ligands, and the subsequent activation of EGFR and ERK1 and ERK2 mitogen-activated protein kinases, were obligatory extracellular steps for the FasL-induced expression of a subset of inflammatory mediators, including CXCL8/interleukin (IL)-8, ICAM-1, IL-1alpha, IL-1beta, CCL20/MIP-3alpha, and thymic stromal lymphopoietin. These results expand the known physiological role of EGFR and its ligands from promoting keratinocyte mitogenesis and survival to mediating FasL-induced epidermal inflammation.

Fas ligand elicits a caspase-independent proinflammatory response in human keratinocytes: implications for dermatitis.

Fas ligand (FasL) causes apoptosis of epidermal keratinocytes and triggers the appearance of spongiosis in eczematous dermatitis. We demonstrate here that FasL also aggravates inflammation by triggering the expression of proinflammatory cytokines, chemokines, and adhesion molecules in keratinocytes. In HaCaT cells and in reconstructed human epidermis (RHE), FasL triggered a NF-kappaB-dependent mRNA accumulation of inflammatory cytokines (tumor necrosis factor-alpha, IL-6, and IL-1beta), chemokines (CCL2/MCP-1, CXCL1/GROalpha, CXCL3/GROgamma, and CXCL8/IL-8), and the adhesion molecule ICAM-1. Oligomerization of Fas was required both for apoptosis and for gene expression. Inhibition of caspase activity abolished FasL-dependent apoptosis; however, it failed to suppress the expression of FasL-induced genes. Additionally, in the presence of caspase inhibitors, but not in their absence, FasL triggered the accumulation of CCL5/RANTES (regulated on activation normal T cell expressed and secreted) mRNA. Our findings identify a novel proinflammatory role of FasL in keratinocytes that is independent of caspase activity and is separable from apoptosis. Thus, in addition to causing spongiosis, FasL may play a direct role in triggering and/or sustaining inflammation in eczemas.

Comparative analysis of immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay using virus-like particles or virus-infected mouse brain antigens to detect IgM antibody in sera from patients with evident flaviviral infections.

The use of immunoglobulin M (IgM) antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA) serves as a valuable tool for the diagnosis of acute flaviviral infections, since IgM antibody titers are detectable early, peak at about 2 weeks postinfection, and subsequently decline to lower levels over the next few months. Traditionally, virus-infected tissue culture or suckling mouse brain (SMB) has been the source of viral antigens used in the assay. In an effort to provide a reliable source of standardized viral antigens for serodiagnosis of the medically important flaviviruses, we have developed a eukaryotic plasmid vector to express the premembrane/membrane and envelope proteins which self-assemble into noninfectious virus-like particles (VLPs). In addition to the plasmids for Japanese encephalitis virus, West Nile virus (WNV), St. Louis encephalitis virus (SLEV), and dengue virus type 2 (DENV-2) reported earlier, we recently constructed the DENV-1, -3, and -4 VLP expression plasmids. Three blind-coded human serum panels were assembled from patients having recent DENV, SLEV, and WNV infections to assess the sensitivity and specificity of the MAC-ELISA using VLPs or SMB antigens. In addition, serum specimens from patients infected with either Powassan virus or La Crosse encephalitis virus were used to evaluate the cross-reactivity of seven mosquito-borne viral antigens. The results of the present studies showed higher sensitivity when using SLEV and WNV VLPs and higher specificity when using SLEV, WNV, and the mixture of DENV-1 to -4 VLPs in the MAC-ELISA than when using corresponding SMB antigens. Receiver operating characteristic (ROC) curve analysis, a plot of the sensitivity versus false positive rate (100 - specificity), was applied to discriminate the accuracy of tests comparing the use of VLPs and SMB antigen. The measurement of assay performance by the ROC analysis indicated that there were statistically significant differences in assay performance between DENV and WNV VLPs and the respective SMB antigens. Additionally, VLPs had a lower cutoff positive/negative ratio than corresponding SMB antigens when employed for the confirmation of current infections. The VLPs also performed better than SMB antigens in the MAC-ELISA, as indicated by a higher positive prediction value and positive likelihood ratio test. Cell lines continuously secreting these VLPs are therefore a significantly improved source of serodiagnostic antigens compared to the traditional sources of virus-infected tissue culture or suckling mouse brain.

Secretion of noninfectious dengue virus-like particles and identification of amino acids in the stem region involved in intracellular retention of envelope protein.

DNA plasmids that express flavivirus premembrane/membrane (prM/M) and envelope (E) proteins in the form of virus-like particles (VLPs) have an excellent potential as DNA vaccine candidates against virus infection. The plasmid-expressed VLPs are also useful as safe, noninfectious antigens in serodiagnostic assays. We have constructed plasmids containing the prM/M and E gene regions for DENV-1, -3, and -4 that express and secrete VLPs when electroporated into Chinese hamster ovary cells. Constructs containing the full-length DENV-1 E protein gene did not secrete VLPs into tissue culture fluid effectively. However, a 16-fold increase in ELISA titers of DENV-1 VLPs was achieved after replacing the carboxy-terminal 20% region of DENV-1 E protein gene with the corresponding sequence of Japanese encephalitis virus (JEV). DENV-3 plasmids containing either the full-length DENV-3 E protein gene or the 20% JEV sequence replacement secreted VLPs to similarly high levels. Whereas DENV-4 VLPs were secreted to high levels by plasmids containing the full-length DENV-4 E protein gene but not by the chimeric plasmid containing 20% JEV E replacement. Domain substitutions by replacing prM/M protein stem-anchor region with the corresponding prM/M stem-anchor region of JEV or DENV-2 in the chimeric DENV-4 construct failed to promote the secretion of DENV-4 VLPs. Using the DENV-2 chimeric plasmid with carboxy-terminal 10% of JEV E gene, the sequence responsible for intracellular localization of E protein was mapped onto the E-H1 alpha-helix domain of DENV-2 E protein. Substitution of three amino acids from the DENV-2 sequence to the corresponding amino acids in the JEV sequence (I398L, M401A, and M412L) in the E-H1 was sufficient to promote extracellular secretion and resulted in detectable titers of DENV-2 VLP secretion.

Noninfectious recombinant antigen for detection of St. Louis encephalitis virus-specific antibodies in serum by enzyme-linked immunosorbent assay.

Proper surveillance of virus activity and a timely response to viral outbreaks depend upon the rapid diagnosis of viral infections. The immunoglobulin M (IgM) antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA) is a fast, sensitive test routinely used for the diagnosis of the medically important West Nile and St. Louis encephalitis flaviviruses. However, the suckling mouse brain-derived (SMB) antigen used in this assay is tedious to prepare and has a risk of exposing personnel to live virus and hazardous chemicals. We report the development of a St. Louis encephalitis virus (SLEV) noninfectious recombinant antigen that is a safe and easily produced alternative antigen for use in diagnostic assays. The expression plasmid pCB8SJ2, containing the premembrane and envelope structural protein-encoding regions of SLEV, was constructed to express secreted extracellular virus-like particles (VLPs) from CHO cells. Blind-coded human serum panels were assembled from patients having recent SLEV, West Nile virus (WNV), Powassan virus, or La Crosse encephalitis virus infections to assess the sensitivity and specificity of assays with SLEV VLP or SMB antigen. MAC-ELISAs with either antigen had comparable sensitivity for the detection of IgM antibodies against SLEV. Importantly, when these two antigens were tested against a human serum panel from patients having recent WNV or Powassan virus infections, the SLEV VLPs were less likely than SMB antigen to detect flavivirus cross-reactive IgM antibodies. An optimized IgG antibody capture ELISA (GAC-ELISA) with both WNV and SLEV VLPs was developed to circumvent the frequently observed higher background in the antigen-capture IgG-ELISA (ACG-ELISA). For the detection of IgG antibodies against WNV, the GAC-ELISA resulted in a statistically significant higher performance accuracy (P = 0.003) than the ACG-ELISA when the WNV VLP antigen was used in both assays. However, no statistical difference was observed in the assay performance of the GAC-ELISA with SLEV VLP or the ACG-ELISA with SLEV SMB antigen.

Recent advancement in flavivirus vaccine development.

Lately, the magnitude of cumulative diseases burden caused by flaviviruses, such as dengue virus, Japanese encephalitis virus, tick-borne encephalitis virus, West Nile virus and yellow fever virus, has reached an unprecedented level with the sizes of human and animal populations at risk increasing sharply. These diseases present highly complex medical, economic and ecologic problems, some effecting primarily human and others affecting human, livestock and wildlife. The large body of recent publications on the development of vaccines taking advantage of new generations of bio-engineering techniques clearly reflects the profound interests and deep sense of urgency in the scientific and medical communities in combating those diseases. This review reveals a collection of remarkable progresses thus far made in flaviviral vaccine research not only employing a diverse range of new strategies but also re-tooling old techniques to improve the existing vaccines. The efficacy and safety of some of the new vaccine candidates have been evaluated and proven in human clinical trials. Besides the technical advancement in vaccine development, in this review, the importance of somewhat neglected and yet critical subjects, such as adequacy of animal model, vaccine safety, vaccine formulation and delivery, complication in serodiagostics and economic factor, was examined in-depth.