Faculty Bibliography

BACKGROUND: A few tau immunotherapies are now in clinical trials with several more likely to be initiated in the near future. A priori, it can be anticipated that an antibody which broadly recognizes various pathological tau aggregates with high affinity would have the ideal therapeutic properties. Tau antibodies 4E6 and 6B2, raised against the same epitope region but of varying specificity and affinity, were tested for acutely improving cognition and reducing tau pathology in transgenic tauopathy mice and neuronal cultures. RESULTS: Surprisingly, we here show that one antibody, 4E6, which has low affinity for most forms of tau acutely improved cognition and reduced soluble phospho-tau, whereas another antibody, 6B2, which has high affinity for various tau species was ineffective. Concurrently, we confirmed and clarified these efficacy differences in an ex vivo model of tauopathy. Alzheimer's paired helical filaments (PHF) were toxic to the neurons and increased tau levels in remaining neurons. Both toxicity and tau seeding were prevented by 4E6 but not by 6B2. Furthermore, 4E6 reduced PHF spreading between neurons. Interestingly, 4E6's efficacy relates to its high affinity binding to solubilized PHF, whereas the ineffective 6B2 binds mainly to aggregated PHF. Blocking 4E6's uptake into neurons prevented its protective effects if the antibody was administered after PHF had been internalized. When 4E6 and PHF were administered at the same time, the antibody was protective extracellularly. CONCLUSIONS: Overall, these findings indicate that high antibody affinity for solubilized PHF predicts efficacy, and that acute antibody-mediated improvement in cognition relates to clearance of soluble phospho-tau. Importantly, both intra- and extracellular clearance pathways are in play. Together, these results have major implications for understanding the pathogenesis of tauopathies and for development of immunotherapies.

Classical immunization methods do not generate catalytic antibodies (catabodies), but recent findings suggest that the innate antibody repertoire is a rich catabody source. We describe the specificity and amyloid beta (Abeta)-clearing effect of a catabody construct engineered from innate immunity principles. The catabody recognized the Abeta C terminus noncovalently and hydrolyzed Abeta rapidly, with no reactivity to the Abeta precursor protein, transthyretin amyloid aggregates, or irrelevant proteins containing the catabody-sensitive Abeta dipeptide unit. The catabody dissolved preformed Abeta aggregates and inhibited Abeta aggregation more potently than an Abeta-binding IgG. Intravenous catabody treatment reduced brain Abeta deposits in a mouse Alzheimer disease model without inducing microgliosis or microhemorrhages. Specific Abeta hydrolysis appears to be an innate immune function that could be applied for therapeutic Abeta removal.

Antibodies or their derivatives as imaging probes for pathological tau protein have great potential, but have not been well studied. In particular, smaller, single-chain-variable antibody fragments (scFv's) are attractive for detecting tau lesions in live subjects. Here, we generated libraries of scFv's and identified numerous phospho-tau-selective scFv's. Peripheral injection of one of these scFv's consistently resulted in a strong in vivo brain signal in transgenic tauopathy mice, but not in wild-type or amyloid-beta plaque mice. The parent tau antibody provided similar results, albeit with a weaker signal intensity. The imaging signal correlated very well with colocalization of the probe with intraneuronal tau aggregates. Both were associated with markers of endosomes, autophagosomes, and lysosomes, suggesting their interaction in these degradation pathways. Such specific antibody-derived imaging probes have great potential as diagnostic markers for Alzheimer's disease and related tauopathies.

Although levels of poly- and perfluoroalkyl substances (PFASs) in human maternal and neonatal blood have been widely reported in the literature, relationship of maternal-fetal transmission of PFASs with carbon chain length is presently not well understood. In this study, 11 PFASs were analyzed in matched samples, including not only maternal blood (MB, n = 31) and cord blood (CB, n = 30), but also placenta (n = 29) and amniotic fluid (AF, n = 29). Except for perfluorohexanoic acid (PFHxA), the detection frequencies of PFASs were similar among placenta, MB, and CB (>80% for 8 PFASs, nondetectable for 2 PFASs). Though only perfluorooctanoic acid (PFOA) was frequently detected (>90%) in AF, with a median concentration of 0.043 ng/mL, other 5 PFASs were also detectable in AF samples with low concentrations (mean: 0.013-0.191 ng/mL). This suggests that in addition to blood-borne in utero exposure, the fetus is also exposed to low levels of PFASs through AF. Concentrations of PFOA in AF were positively correlated with those in MB (r = 0.738, p < 0.01) and CB (r = 0.683, p < 0.001), suggesting that AF concentration could reflect fetal PFOA exposure during pregnancy and can be used as a biomarker. To clarify the effects of carbon chain length on maternal transfer of PFASs, we calculated maternal transfer efficiencies of PFASs from MB to CB (TMB-CB). A U-shaped trend in TMB-CB of C7-C12 perfluoroalkyl carboxylic acids (PFCAs) with increasing carbon chain length was found in this study for the first time. The U-shaped TMB-CB of PFCAs with carbon chain length is an integrated result of opposite trend of the ratios between MB/placenta and placenta/CB based on carbon chain length. This is the first study to report the occurrence of PFASs in human placenta. The results reported here enable better understanding of the maternal-fetal transmission of PFASs.

Hearts utilize fatty acids as a primary source of energy. The sources of those lipids include free fatty acids and lipoprotein triglycerides. Deletion of the primary triglyceride-hydrolyzing enzyme lipoprotein lipase (LPL) leads to cardiac dysfunction. Whether heart LPL-knockout (hLPL0) mice are compromised due a deficiency in energetic substrates is unknown. To test whether alternative sources of energy will prevent cardiac dysfunction in hLPL0 mice, two different models were used to supply nonlipid energy. 1) hLPL0 mice were crossed with mice transgenically expressing GLUT1 in cardiomyocytes to increase glucose uptake into the heart; this cross-corrected cardiac dysfunction, reduced cardiac hypertrophy, and increased myocardial ATP. 2) Mice were randomly assigned to a sedentary or training group (swimming) at 3 mo of age, which leads to increased skeletal muscle production of lactate. hLPL0 mice had greater expression of the lactate transporter monocarboxylate transporter-1 (MCT-1) and increased cardiac lactate uptake. Compared with hearts from sedentary hLPL0 mice, hearts from trained hLPL0 mice had adaptive hypertrophy and improved cardiac function. We conclude that defective energy intake and not the reduced uptake of fat-soluble vitamins or cholesterol is responsible for cardiac dysfunction in hLPL0 mice. In addition, our studies suggest that adaptations in cardiac metabolism contribute to the beneficial effects of exercise on the myocardium of patients with heart failure.

BACKGROUND: The prognosis of metastatic melanomas to the brain (MBM) is variable with prolonged survival in a subset. It is unclear whether MBM differ from extracranial metastases (EcM) and primary melanomas (PrM). METHODS: To study the biology of MBM, histopathologic analysis of tumor blocks from patients' craniotomy samples and whole-genome expression profiling (WGEP) with confirmatory immunohistochemistry were performed. RESULTS: High mononuclear infiltrate and low intratumoral hemorrhage were associated with prolonged overall survival (OS). Pathway analysis of WGEP data from 29 such craniotomy tumor blocks demonstrated that several immune-related BioCarta gene sets were associated with prolonged OS. WGEP analysis of MBM in comparison with same-patient EcM and PrM showed that MBM and EcM were similar, but both differ significantly from PrM. Immunohistochemical analysis revealed that peritumoral CD3(+) and CD8(+) cells were associated with prolonged OS. CONCLUSIONS: MBMs are more similar to EcM compared with PrM. Immune infiltrate is a favorable prognostic factor for MBM.

A long standing problem with antidepressant drugs is their delayed onsets of action which has made them unsatisfactory in the rapid treatment of serious depressions involving agitated and suicidal behavior. Two new approaches to this problem involve the glutamatergic antagonist, ketamine, recently reviewed, and the acute inhibition of central stress circuits, which is the subject of the present review. The rationale behind stress-circuit inhibition comes from the findings that both clinical and experimental depressions are accompanied by increased neural activity in the stress network together with inhibited activity in regions underlying active motivated behaviors, and that both changes are reversed by effective antidepressant treatment. It has been shown further that direct pharmacological inhibition of central noradrenergic stress nuclei produces immediate reversal of depressive-like passive as well as sickness behaviors. Dipivalyl-6-fluoronorepinephrine (dp6FNE), a brain-permeable pro-drug of 6FNE, a full agonist at inhibitory brain alpha- adrenoceptors in brainstem noradrenergic stress nuclei, has been developed and found in preliminary studies to cause rapid reversal of both passivity and anhedonia as well as anxiolysis without significant hypoactivity in the open field. Low doses of agonists of glucocorticoid and 5HT1A autoreceptors, which respectively inhibit the hypothalamic-pituitaryadrenal axis and serotonergic stress systems, may also share these effects as well as potentiate the actions of dp6FNE. Anti-stress effects may also be involved in the rapid therapeutic effects found with intracerebral administration of first generation antidepressants and may prove helpful in potentiating the therapeutic actions of stimulants. Stone et al

Despite the growing public interest in perfluorinated compounds (PFCs), very few studies have reported the sources and pathways of human exposure to these compounds in China. In this study, concentrations of 10 PFCs were measured in human blood, water (tap water and surface water), freshwater fish, and seafood samples collected from China. On the basis of the data, we calculated daily intakes of PFCs, regional differences in human exposures, and potential risks associated with ingestion of PFCs from diet, drinking water, and indoor dust for the Chinese population. Perfluorooctane sulfonate (PFOS) was the most predominant PFC found with a mean concentration of 12.5 ng/mL in human blood from Tianjin and 0.92 ng/g wet wt in freshwater fish and seafood; perfluorooctanoic acid (PFOA) was the major PFC found in drinking water at a concentration range of 0.10 to 0.92 ng/L. The estimated daily intake of PFOS and PFOA via fish and seafood consumption (EDI(fish&seafood)) ranged from 0.10 to 2.51 and 0.13 to 0.38 ng/kg bw/day, respectively, for different age groups (i.e., toddlers, adolescents and children, and adults) from selected locations (i.e., Tianjin, Nanchang, Wuhan, and Shenyang). The EDI(fish&seafood) of PFCs decreased (p < 0.05) with age. The estimated daily intake of PFOS and PFOA via drinking water consumption (EDI(drinking water)) ranged from 0.006 to 0.014 and 0.010 to 0.159 ng/kg bw/day, respectively. Comparison of EDI(fish&seafood) and EDI(drinking water) values with those of the modeled total dietary intake (TDI) of PFCs by adults from Tianjin, Nanchang, Wuhan, and Shenyang showed that contributions of fish and seafood to TDI of PFOS varied depending on the location. Fish and seafood accounted for 7%, 24%, 80%, and 84% of PFOS intake in Nanchang, Shenyang, Wuhan, and Tianjin, respectively, suggesting regional differences in human exposure to PFOS. Drinking water was a minor source of PFOS (<1%) exposure in adults from all the study locations.

The present study examined the ability of 6-fluoronorepinephrine (6FNE), a full selective alpha-adrenoceptor agonist, to produce antidepressant-like effects in mice. The drug, administered in the 4th ventricle, produced marked anti-immobility effects at mid-dose range in the acute forced swim, tail suspension and repeated open-space forced swim tests with minimal effect on open-field motor activity and also reversed anhedonia following lipopolysaccharide administration. Its antidepressant effects were equal to or greater than that of an established systemic antidepressant, desmethylimipramine, given subacutely. Experiments with alpha-adrenoceptor antagonists indicated that the drug acts primarily via the alpha2-receptor in contrast to endogenous catecholamines which appear to control depressive behaviour primarily via the alpha1-receptor. Antidepressant activity declined at higher doses signifying a possible pro-depressant effect of one of the alpha-adrenoceptor subtypes. Compared to the selective alpha2-agonist, dexmedetomidine, 6FNE showed equivalent antidepressant action in the tail suspension test but appeared to have a greater efficacy or speed of action in the repeated open-space forced swim test which produces a more sustained depression. Studies of regional brain Fos expression induced during the antidepressant tests showed that 6FNE tended to inhibit neural activity in two stress-responsive regions (locus coeruleus and paraventricular hypothalamus) but to enhance activity in two areas involved in motivated behaviour (nucleus accumbens shell and lateral septal nucleus) producing a neural pattern consistent with antidepressant action. It is concluded that 6FNE elicits a rapid and effective antidepressant and anti-stress response that may compare favourably with available antidepressants

This protocol describes a simplified method for inducing a chronic depression-like state in mice that is based on the repeated open-space forced swim method originally developed for rats. The method consists of mice swimming daily in lukewarm water in rat tub cages, for 15 min/day for 4 days, and thereafter once per week. This procedure produces a progressive decrease in distance swum and a concomitant increase in immobility (floating) in approximately 70% of the mice, both of which persist unaltered for weeks. The model has predictive, face, and construct validity and has a number of advantages over previous methods in that it utilizes very mild stress, is short in duration, and is easily standardized. Moreover, since it utilizes a greater swimming area than the traditional (Porsolt) method it can be used to study interactions of depressive behavior with behavioral flexibility and perseveration. Curr. Protoc. Neurosci. 54:9.36.1-9.36.8. (c) 2011 by John Wiley & Sons, Inc