Hippocampal Inflammation and Gene Expression Changes in Peripheral Lipopolysaccharide Challenged Mice Showing Sickness and Anxiety-Like Behaviors.

Neuroinflammation is often associated with the development of depressive and anxiety disorders. The hippocampus is one of the brain regions affected by inflammation that is associated with these symptoms. However, the mechanism of hippocampal inflammation-induced emotional behavior remains unknown. The aim of this study was to clarify temporal changes in the neuroinflammatory responses in the hippocampus and the response of dentate gyrus (DG) neurons using peripheral lipopolysaccharide (LPS)-challenged mice. LPS administration induced anxiety-like activity in the elevated plus maze test and social interaction test after 24 h, at which time the mice had recovered from sickness behavior. We examined the hippocampal inflammation-related gene expression changes over time. The expression of interleukin-1ß (Il1b) and tumor necrosis factor α (Tnfa) was rapidly enhanced and sustained until 24 h after LPS administration, whereas the expression of Il6 was transiently induced at approx. 6 h. IL-6-dependent downstream signaling of transducer and activator of transcription 3 (STAT3) was also activated approx. 3-6 h after LPS treatment. The expression of innate immune genes including interferon-induced transmembrane proteins such as interferon-induced transmembrane protein 1 (Ifitm1) and Ifitm3 and complement factors such as C1qa and C1qb started to increase approx. 6 h and showed sustained or further increase at 24 h. We also examined changes in the expression of several maturation markers in the DG and found that LPS enhanced the expression of calbindin 1 (Calb1), tryptophan-2,3-dioxigenase 2 (Tdo2), Il1rl, and neurotrophin-3 (Ntf3) at 24 h after LPS treatment. Collectively, these results demonstrate temporal changes of inflammation and gene expression in the hippocampus in LPS-induced sickness and anxiety-like behaviors.

Overexpression of NT-3 in the hippocampus suppresses the early phase of the adult neurogenic process.

The dentate gyrus (DG) of the hippocampus regulates stress-related emotional behaviors and ensures neurogenesis throughout life. Neurotrophin-3 (NT-3) is a neurotrophic factor that regulates neuronal differentiation, survival, and synaptic formation in both the peripheral and central nervous systems. NT-3 is expressed in the adult DG of the hippocampus; several chronic stress conditions enhance NT-3 expression in rodents. However, functional modulation of the adult DG by NT-3 signaling remains unclear. To directly investigate the impact of NT-3 on DG function, NT-3 was overexpressed in the hippocampal ventral DG by an adeno-associated virus carrying NT-3 (AAV-NT-3). Four weeks following the AAV-NT-3 injection, high NT-3 expression was observed in the ventral DG. We examined the influence of NT-3 overexpression on the neuronal responses and neurogenic processes in the ventral DG. NT-3 overexpression significantly increased the expression of the mature DG neuronal marker calbindin and immediate early genes, such as Fos and Fosb, thereby suggesting DG neuronal activation. During neurogenesis, the number of proliferating cells and immature neurons in the subgranular zone of the DG significantly decreased in the AAV-NT-3 group. Among the neurogenesis-related factors, Vegfd, Lgr6, Bmp7, and Drd1 expression significantly decreased. These results demonstrated that high NT-3 levels in the hippocampus regulate the activation of mature DG neurons and suppress the early phase of neurogenic processes, suggesting a possible role of NT-3 in the regulation of adult hippocampal function under stress conditions.

TrkB Signaling in Dorsal Raphe Nucleus is Essential for Antidepressant Efficacy and Normal Aggression Behavior.

Brain-derived neurotrophic factor (BDNF) and its high affinity receptor, tropomyosin receptor kinase B (TrkB), have important roles in neural plasticity and are required for antidepressant efficacy. Studies examining the role of BDNF-TrkB signaling in depression and antidepressant efficacy have largely focused on the limbic system, leaving it unclear whether this signaling is important in other brain regions. BDNF and TrkB are both highly expressed in the dorsal raphe nucleus (DRN), a brain region that has been suggested to have a role in depression and antidepressant action, although it is unknown whether BDNF and TrkB in the dorsal raphe nucleus are involved in these processes. We combined the adeno-associated virus (AAV) with the Cre-loxP site-specific recombination system to selectively knock down either Bdnf or TrkB in the DRN. These mice were then characterized in several behavioral paradigms including measures of depression-related behavior and antidepressant efficacy. We show that knockdown of TrkB, but not Bdnf, in the DRN results in loss of antidepressant efficacy and increased aggression-related behavior. We also show that knockdown of TrkB or Bdnf in this brain region does not have an impact on weight, activity levels, anxiety, or depression-related behaviors. These data reveal a critical role for TrkB signaling in the DRN in mediating antidepressant responses and normal aggression behavior. The results also suggest a non-cell autonomous role for BDNF in the DRN in mediating antidepressant efficacy.

Immunogenicity of trivalent influenza vaccine in patients with lung cancer undergoing anticancer chemotherapy.

Lung cancer is a leading cause of cancer-related death, and patients with lung cancer are a priority group for influenza vaccination. However, few studies have assessed the immunogenicity of the influenza vaccine in these patients. Here, we performed a prospective study to evaluate the immunogenicity of the influenza vaccine in patients with lung cancer undergoing anticancer chemotherapy. Twenty-five patients with lung cancer undergoing anticancer chemotherapy and 26 patients with chronic obstructive pulmonary disease (COPD) as controls were enrolled. A trivalent influenza vaccine containing inactivated A/California/7/2009 (H1N1) pdm09, A/Texas/50/2012 (H3N2), and B/Massachusetts/2/2012 was administered as a single subcutaneous injection. Serum samples were collected before vaccination, and at 4-6 weeks after vaccination. Levels of serum antibody to hemagglutinin were measured. Among patients with lung cancer, the seroprotection rate (postvaccination titer > 1:40) was 84% for both A(H1N1) and A(H3N2), similar to the levels observed in patients with COPD. However, the seroprotection rate for the B strain was significantly lower in patients with lung cancer than in patients with COPD (64% versus 92%). Even after adjustment for potential confounders, patients with lung cancer had a significantly lower odds ratio for seroprotection against the B strain than patients with COPD. Moreover, in patients with lung cancer, those receiving the platinum doublet treatment tended to exhibit a lower seroprotection rate than those receiving a single agent. Thus, patients with lung cancer undergoing anticancer chemotherapy showed acceptable immune responses to a trivalent influenza vaccine, supporting the recommendation for annual influenza vaccination in these patients.

Functional labeling of neurons and their projections using the synthetic activity-dependent promoter E-SARE.

Identifying the neuronal ensembles that respond to specific stimuli and mapping their projection patterns in living animals are fundamental challenges in neuroscience. To this end, we engineered a synthetic promoter, the enhanced synaptic activity-responsive element (E-SARE), that drives neuronal activity-dependent gene expression more potently than other existing immediate-early gene promoters. Expression of a drug-inducible Cre recombinase downstream of E-SARE enabled imaging of neuronal populations that respond to monocular visual stimulation and tracking of their long-distance thalamocortical projections in living mice. Targeted cell-attached recordings and calcium imaging of neurons in sensory cortices revealed that E-SARE reporter expression correlates with sensory-evoked neuronal activity at the single-cell level and is highly specific to the type of stimuli presented to the animals. This activity-dependent promoter can expand the repertoire of genetic approaches for high-resolution anatomical and functional analysis of neural circuits.

Characterization of meFucoidan as a selective inhibitor for secretory phospholipase A2-IIA and the phosphorylation of meFucoidan-binding proteins by A-kinase in vitro.

The direct interaction of Mekabu fucoidan (meFucoidan) with four functional basic proteins (sPLA2-IIA, bFGF, histone H2B and HBV core protein) and three synthetic FGF-BP peptides (sp5, GE13 and RS6) was characterized in vitro. It was found that (i) meFucoidan inhibited dose-dependently the activity of sPLA2-IIA, but not pPLA2, through its direct binding to the enzyme; (ii) sPLA2-IIA activity was sensitive to meFucoidan rather than heparin, but significantly stimulated by sulfatide; (iii) the A-kinase-mediated phosphorylation of these basic proteins, except sPLA2-IIA, and synthetic peptides, containing potent phosphorylation sites for A-kinase, was inhibited dose-dependently by meFucoidan; and (iv) two consensus meFucoidan-binding motifs (B-B-B-B-X and B-X-B-B-X; B, basic amino acid) in these basic proteins and synthetic peptides could be overlapping to the potent phosphorylation site (B-B-X-S/T) for the kinase in vitro. These results presented here suggest that meFucoidan functions as a selective inhibitor for sPLA2-IIA and the A-kinase-mediated phosphorylation of cellular meFucoidan-binding functional basic proteins in vitro.