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Serum levels of inflammatory cytokines, for example, tumor necrosis factor alpha (TNF α ), interleukin-6 (IL-6), and IL-1 beta (IL-1 β ), are elevated in subjects with major depressive disorder (MDD). The reason why this occurs is unclear. Elevated levels of inflammatory cytokines could be a result of brain dysfunction in MDD. It is also possible that inflammatory cytokines contribute to depressive symptoms in MDD. If the first assumption is correct, one would expect levels to normalize with resolution of the depressive episode after treatment. Several studies have measured changes in cytokine levels during antidepressant treatment; however, the results vary. The purpose of this study was to pool all available data on changes in serum levels of TNF α , IL-6, and IL-1 β during antidepressant treatment to determine whether these levels change. Studies were included if they used an approved pharmacological treatment for depression, patients had a diagnosis of MDD, and serum levels of TNF α , IL-6, and/or IL-1 β were measured before and after treatment. Twenty-two studies fulfilled these criteria. Meta-analysis of these studies showed that, overall, while pharmacological antidepressant treatment reduced depressive symptoms, it did not reduce serum levels of TNF α . On the other hand, antidepressant treatment did reduce levels of IL-1 β and possibly those of IL-6. Stratified subgroup analysis by class of antidepressant indicated that serotonin reuptake inhibitors may reduce levels of IL-6 and TNF α . Other antidepressants, while efficacious for depressive symptoms, did not appear to reduce cytokine levels. These results argue against the notion that resolution of a depressive episode is associated with normalization of levels of circulating inflammatory cytokines; however, the results are consistent with the possibility that inflammatory cytokines contribute to depressive symptoms and that antidepressants block the effects of inflammatory cytokines on the brain.

The interaction of the neuronal protein α-synuclein with lipid membranes appears crucial in the context of Parkinson’s disease, but the underlying mechanistic details, including the roles of different lipids in pathogenic protein aggregation and membrane disruption, remain elusive. Here, we used single-vesicle resolution fluorescence and label-free scattering microscopy to investigate the interaction kinetics of monomeric α-synuclein with surface-tethered vesicles composed of different negatively charged lipids. Supported by a theoretical model to account for structural changes in scattering properties of surface-tethered lipid vesicles, the data demonstrate stepwise vesicle disruption and asymmetric membrane deformation upon α-synuclein binding to phosphatidylglycerol vesicles at protein concentrations down to 10 nM (∼100 proteins per vesicle). In contrast, phosphatidylserine vesicles were only marginally affected. These insights into structural consequences of α-synuclein interaction with lipid vesicles highlight the contrasting roles of different anionic lipids, which may be of mechanistic relevance for both normal protein function (e.g., synaptic vesicle binding) and dysfunction (e.g., mitochondrial membrane interaction).

Neuroinflammation is associated with a broad spectrum of neurodegenerative and psychiatric diseases. The core process in neuroinflammation is activation of microglia, the innate immune cells of the brain. We measured the neuroinflammatory response produced by a systemic administration of theEscherichia colilipopolysaccharide (LPS; also called endotoxin) in humans with the positron emission tomography (PET) radiotracer [11C]PBR28, which binds to translocator protein, a molecular marker that is up-regulated by microglial activation. In addition, inflammatory cytokines in serum and sickness behavior profiles were measured before and after LPS administration to relate brain microglial activation with systemic inflammation and behavior. Eight healthy male subjects each had two 120-min [11C]PBR28 PET scans in 1 d, before and after an LPS challenge. LPS (1.0 ng/kg, i.v.) was administered 180 min before the second [11C]PBR28 scan. LPS administration significantly increased [11C]PBR28 binding 30–60%, demonstrating microglial activation throughout the brain. This increase was accompanied by an increase in blood levels of inflammatory cytokines, vital sign changes, and sickness symptoms, well-established consequences of LPS administration. To our knowledge, this is the first demonstration in humans that a systemic LPS challenge induces robust increases in microglial activation in the brain. This imaging paradigm to measure brain microglial activation with [11C]PBR28 PET provides an approach to test new medications in humans for their putative antiinflammatory effects.

Microglia play an essential role in many brain diseases. Microglia are activated by local tissue damage or inflammation, but systemic inflammation can also activate microglia. An important clinical question is whether the effects of systemic inflammation on microglia mediate the deleterious effects of systemic inflammation in diseases such as Alzheimer's dementia, multiple sclerosis, and stroke. Positron Emission Tomography (PET) imaging with ligands that bind to Translocator Protein (TSPO) can be used to detect activated microglia. The aim of this study was to evaluate whether the effect of systemic inflammation on microglia could be measured with PET imaging in nonhuman primates, using the TSPO ligand [11C]PBR28. Six female baboons (Papio anubis) were scanned before and at 1h and/or 4h and/or 22h after intravenous administration of E. coli lipopolysaccharide (LPS; 0.1mg/kg), which induces systemic inflammation. Regional time-activity data from regions of interest (ROIs) were fitted to the two-tissue compartmental model, using the metabolite-corrected arterial plasma curve as input function. Total volume of distribution (VT) of [11C]PBR28 was used as a measure of total ligand binding. The primary outcome was change in VT from baseline. Serum levels of tumor necrosis factor alpha (TNFα), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and interleukin-8 (IL-8) were used to assess correlations between systemic inflammation and microglial activation. In one baboon, immunohistochemistry was used to identify cells expressing TSPO. LPS administration increased [11C]PBR28 binding (F(3,6)=5.1, p=.043) with a 29±16% increase at 1h (n=4) and a 62±34% increase at 4h (n=3) post-LPS. There was a positive correlation between serum IL-1β and IL-6 levels and the increase in [11C]PBR28 binding. TSPO immunoreactivity occurred almost exclusively in microglia and rarely in astrocytes. In the nonhuman-primate brain, LPS-induced systemic inflammation produces a robust increase in the level of TSPO that is readily detected with [11C]PBR28 PET. The effect of LPS on [11C]PBR28 binding is likely mediated by inflammatory cytokines. Activation of microglia may be a mechanism through which systemic inflammatory processes influence the course of diseases such as Alzheimer's, multiple sclerosis, and possibly depression. ► PET imaging can detect microglial activation after lipopolysaccharide administration. ► Systemic inflammation led to increased [11C]PBR28 binding in the brain. ► The increase in binding correlated with blood levels of inflammatory cytokines. ► The effect of systemic inflammation on microglia can be detected with PET. ► Relevant to brain diseases in which systemic inflammation affects disease progression.

Depression is associated with systemic inflammation, and the systemic inflammation caused by endotoxin administration elicits mild depressive symptoms such as fatigue and reduced interest. The neural correlates of depressive symptoms that result from systemic inflammation are poorly defined. The aim of this study was to use (18)F-FDG PET to identify brain regions involved in the response to endotoxin administration in humans. Nine healthy subjects received double-blind endotoxin (0.8 ng/kg) and placebo on different days. (18)F-FDG PET was used to measure differences in the cerebral metabolic rate of glucose in the following regions of interest: insula, cingulate, and amygdala. Serum levels of tumor necrosis factor-α and interleukin-6 were used to gauge the systemic inflammatory response, and depressive symptoms were measured with the Montgomery-Åsberg Depression Rating Scale and other scales. Endotoxin administration was associated with an increase in Montgomery-Åsberg Depression Rating Scale, increased fatigue, reduced social interest, increased levels of inflammatory cytokines, higher normalized glucose metabolism (NGM) in the insula, and, at a trend level, lower NGM in the cingulate. Secondary analyses of insula and cingulate subregions indicated that these changes were driven by the right anterior insula and the right anterior cingulate. There was a negative correlation between peak cytokine levels and change in social interest and between peak cytokine levels and change in insula NGM. There was a positive correlation between the change in NGM in the insula and change in social interest. Systemic inflammation in humans causes an increase in depressive symptoms and concurrent changes in glucose metabolism in the insula and cingulate-brain regions that are involved in interoception, positive emotionality, and motivation.

TQS‐168, a first‐in‐class small‐molecule inducer of peroxisome proliferator‐activated receptor gamma coactivator 1‐alpha gene expression, is in development for the treatment of amyotrophic lateral sclerosis. A single‐ascending‐dose (SAD) and multiple‐ascending‐dose (MAD) study of TQS‐168 was carried out in healthy male subjects to investigate safety, tolerability, pharmacokinetics (PK), food effect, and preliminary pharmacodynamic effects (PD). Since solubility enhancement could be beneficial, assessment of three formulations was incorporated into the study using an integrated rapid manufacturing and clinical testing approach. Dosing in the SAD part was initiated with a crystalline methylcellulose (MC) suspension, and then spray‐dried dispersion (SDD) and hot‐melt extrusion (HME) suspensions were evaluated. The HME and SDD formulations showed two and fourfold higher exposure than the MC suspension, respectively, and the SDD formulation was selected for progression to subsequent SAD and MAD cohorts, in which there was further investigation of the food effect on exposure in addition to assessments of safety, tolerability, PK, and PD. Cmax and AUC plasma exposures of TQS‐168 were supra‐proportional at higher doses, irrespective of formulation. Median Tmax for TQS‐168 occurred between 0.5 and 4.0 h post‐dose and occurred later with higher doses. Geometric mean half‐lives (T1/2) for TQS‐168 were independent of formulation and food, ranging from 3.2 to 10.5 h following single doses and 4.1 to 7.3 h following multiple doses. Food blunted TQS‐168 Cmax but had minimal impact on AUC. TQS‐168 was considered to be safe and generally well tolerated following single and multiple oral doses. The SDD formulation was selected for future patient studies.

Targeting immune-mediated, age-related, biology has the potential to be a transformative therapeutic strategy. However, the redundant nature of the multiple cytokines that change with aging requires identification of a master downstream regulator to successfully exert therapeutic efficacy. Here, we discovered CCR3 as a prime candidate, and inhibition of CCR3 has pro-cognitive benefits in mice, but these benefits are not driven by an obvious direct action on central nervous system (CNS)-resident cells. Instead, CCR3-expressing T cells in the periphery that are modulated in aging inhibit infiltration of these T cells across the blood-brain barrier and reduce neuroinflammation. The axis of CCR3-expressing T cells influencing crosstalk from periphery to brain provides a therapeutically tractable link. These findings indicate the broad therapeutic potential of CCR3 inhibition in a spectrum of neuroinflammatory diseases of aging. CCR3 is shown to play a role in age-related T cell infiltration into the brain in mice as well as age-related changes in cognition, highlighting its therapeutic potential for age-related diseases.

BackgroundAntiepileptic drugs, levetiracetam (LEV) and brivaracetam (BRV), bind to synaptic vesicle glycoprotein 2A (SV2A). In their anti-seizure activity, speed of brain entry may be an important factor. BRV showed faster entry into the human and non-human primate brain, based on more rapid displacement of SV2A tracer 11C-UCB-J. To extract additional information from previous human studies, we developed a nonlinear model that accounted for drug entry into the brain and binding to SV2A using brain 11C-UCB-J positron emission tomography (PET) data and the time-varying plasma drug concentration, to assess the kinetic parameter K1 (brain entry rate) of the drugs.MethodDisplacement (LEV or BRV p.i. 60 min post-tracer injection) and post-dose scans were conducted in five healthy subjects. Blood samples were collected for measurement of drug concentration and the tracer arterial input function. Fitting of nonlinear differential equations was applied simultaneously to time-activity curves (TACs) from displacement and post-dose scans to estimate 5 parameters: K1 (drug), K1(11C-UCB-J, displacement), K1(11C-UCB-J, post-dose), free fraction of 11C-UCB-J in brain (fND(11C-UCB-J)), and distribution volume of 11C-UCB-J (VT(UCB-J)). Other parameters (KD(drug), KD(11C-UCB-J), fP(drug), fP(11C-UCB-J, displacement), fP(11C-UCB-J, post-dose), fND(drug), koff(drug), koff(11C-UCB-J)) were fixed to literature or measured values.ResultsThe proposed model described well the TACs in all subjects; however, estimates of drug K1 were unstable in comparison with 11C-UCB-J K1 estimation. To provide a conservative estimate of the relative speed of brain entry for BRV vs. LEV, we determined a lower bound on the ratio BRV K1/LEV K1, by finding the lowest BRV K1 or highest LEV K1 that were statistically consistent with the data. Specifically, we used the F test to compare the residual sum of squares with fixed BRV K1 to that with floating BRV K1 to obtain the lowest possible BRV K1; the same analysis was performed to find the highest LEV K1. The lower bound of the ratio BRV K1/LEV K1 was ~ 7.ConclusionsUnder appropriate conditions, this advanced nonlinear model can directly estimate entry rates of drugs into tissue by analysis of PET TACs. Using a conservative statistical cutoff, BRV enters the brain at least sevenfold faster than LEV.

Introduction This phase 2 trial evaluated the safety, tolerability, and feasibility of repeated infusions of the plasma fraction GRF6019 in mild‐to‐moderate Alzheimer's disease. Methods In this randomized, double‐blind, dose‐comparison trial, 47 patients were randomized 1:1 to receive daily infusions of 100 mL (n = 24) or 250 mL (n = 23) of GRF6019 for 5 consecutive days over two dosing periods separated by a treatment‐free interval of 3 months. Results The mean (standard deviation [SD]) age of the enrolled patients was 74.3 (6.9), and 62% were women. Most adverse events (55%) were mild, with no clinically significant differences in safety or tolerability between the two dose levels. The mean (SD) baseline Mini‐Mental State Examination score was 20.6 (3.7) in the 100 mL group and 19.6 (3.7) in the 250 mL group; at 24 weeks, the within‐patient mean change from baseline was –1.0 points (95% confidence interval [CI], –3.1 to 1.1) in the 100 mL group and +1.5 points (95% CI, –0.4 to 3.3) in the 250 mL group. The within‐patient mean change from baseline on the Alzheimer's Disease Assessment Scale‐Cognitive subscale was –0.4 points (95% CI, –2.9 to 2.2) in the 100 mL group, while in the 250 mL group it was –0.9 points (95% CI, –3.0 to 1.2). The within‐patient mean change from baseline on the Alzheimer's Disease Cooperative Study‐Activities of Daily Living was –0.7 points in the 100 mL group (95% CI, –4.3 to 3.0) and –1.3 points (95% CI, –3.4 to 0.7) in the 250 mL group. The mean change from baseline on the Category Fluency Test, Clinical Dementia Rating Scale–Sum of Boxes, Alzheimer's Disease Cooperative Study–Clinical Global Impression of Change, and Neuropsychiatric Inventory Questionnaire was similar for both treatment groups and did not show any worsening. Discussion GRF6019 was safe and well tolerated, and patients experienced no cognitive decline and minimal functional decline. These results support further development of GRF6019.

We conducted a meta-analysis of randomized, placebo-controlled trials of omega-3 fatty acid (FA) treatment of major depressive disorder (MDD) in order to determine efficacy and to examine sources of heterogeneity between trials. PubMed (1965-May 2010) was searched for randomized, placebo-controlled trials of omega-3 FAs for MDD. Our primary outcome measure was standardized mean difference in a clinical measure of depression severity. In stratified meta-analysis, we examined the effects of trial duration, trial methodological quality, baseline depression severity, diagnostic indication, dose of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in omega-3 preparations, and whether omega-3 FA was given as monotherapy or augmentation. In 13 randomized, placebo-controlled trials examining the efficacy of omega-3 FAs involving 731 participants, meta-analysis demonstrated no significant benefit of omega-3 FA treatment compared with placebo (standard mean difference (SMD)=0.11, 95% confidence interval (CI): −0.04, 0.26). Meta-analysis demonstrated significant heterogeneity and publication bias. Nearly all evidence of omega-3 benefit was removed after adjusting for publication bias using the trim-and-fill method (SMD=0.01, 95% CI: −0.13, 0.15). Secondary analyses suggested a trend toward increased efficacy of omega-3 FAs in trials of lower methodological quality, trials of shorter duration, trials which utilized completers rather than intention-to-treat analysis, and trials in which study participants had greater baseline depression severity. Current published trials suggest a small, non-significant benefit of omega-3 FAs for major depression. Nearly all of the treatment efficacy observed in the published literature may be attributable to publication bias.