Influenza vaccination in early Alzheimer's disease rescues amyloidosis and ameliorates cognitive deficits in APP/PS1 mice by inhibiting regulatory T cells.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative disorder strongly correlated with a dysfunctional immune system. Our previous results demonstrated that inactivated influenza vaccine (IIV) facilitates hippocampal neurogenesis and blocks lipopolysaccharide (LPS)-induced cognitive impairment. However, whether IIV improves cognitive deficits in an AD mouse model remains unclear. In addition, early interventions in AD have been encouraged in recent years. Here, we investigated whether IIV immunization at the preclinical stage of AD alters the brain pathology and cognitive deficits in an APP/ PS1 mouse model. METHODS: We assessed spatial learning and memory using Morris water maze (MWM). The brain ß-amyloid (Aß) plaque burden and activated microglia were investigated by immunohistochemistry. Furthermore, flow cytometry was utilized to analyze the proportions of Treg cells in the spleen. A cytokine antibody array was performed to measure the alteration of cytokines in the brain and peripheral immune system. RESULTS: Five IIV immunizations activated microglia, reduced the Aß burden and improved the cognitive impairment. Simultaneously, the IIV-induced immune response broke peripheral immunosuppression by reducing Foxp3+ regulatory T cell (Treg) activities, whereas the restoration of Treg level in the periphery using all-trans retinoic acid (ATRA) blunted the protective effects of IIV on Aß burden and cognitive functions. Interestingly, IIV immunization might increase proinflammatory and anti-inflammatory cytokine expression in the brain of APP/PS1 mice, enhanced microglial activation, and enhanced the clustering and phagocytosis of Aß, thereby creating new homeostasis in the disordered immune microenvironment. CONCLUSIONS: Altogether, our results suggest that early multiple IIV immunizations exert a beneficial immunomodulatory effect in APP/PS1 mice by breaking Treg-mediated systemic immune tolerance, maintaining the activation of microglia and removing of Aß plaques, eventually improving cognitive deficits.

Prenatal influenza vaccination rescues impairments of social behavior and lamination in a mouse model of autism.

BACKGROUND: Prenatal infection is a substantial risk factor for neurodevelopmental disorders such as autism in offspring. We have previously reported that influenza vaccination (VAC) during early pregnancy contributes to neurogenesis and behavioral function in offspring. RESULTS: Here, we probe the efficacy of VAC pretreatment on autism-like behaviors in a lipopolysaccharide (LPS)-induced maternal immune activation (MIA) mouse model. We show that VAC improves abnormal fetal brain cytoarchitecture and lamination, an effect associated with promotion of intermediate progenitor cell differentiation in MIA fetal brain. These beneficial effects are sufficient to prevent social deficits in adult MIA offspring. Furthermore, whole-genome analysis suggests a strong interaction between Ikzf1 (IKAROS family zinc-finger 1) and neuronal differentiation. Intriguingly, VAC rescues excessive microglial Ikzf1 expression and attenuates microglial inflammatory responses in the MIA fetal brain. CONCLUSIONS: Our study implies that a preprocessed influenza vaccination prevents maternal bacterial infection from causing neocortical lamination impairments and autism-related behaviors in offspring.

Silibinin inhibits acetylcholinesterase activity and amyloid ß peptide aggregation: a dual-target drug for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is characterized by amyloid ß (Aß) peptide aggregation and cholinergic neurodegeneration. Therefore, in this paper, we examined silibinin, a flavonoid extracted from Silybum marianum, to determine its potential as a dual inhibitor of acetylcholinesterase (AChE) and Aß peptide aggregation for AD treatment. To achieve this, we used molecular docking and molecular dynamics simulations to examine the affinity of silibinin with Aß and AChE in silico. Next, we used circular dichroism and transmission electron microscopy to study the anti-Aß aggregation capability of silibinin in vitro. Moreover, a Morris Water Maze test, enzyme-linked immunosorbent assay, immunohistochemistry, 5-bromo-2-deoxyuridine double labeling, and a gene gun experiment were performed on silibinin-treated APP/PS1 transgenic mice. In molecular dynamics simulations, silibinin interacted with Aß and AChE to form different stable complexes. After the administration of silibinin, AChE activity and Aß aggregations were down-regulated, and the quantity of AChE also decreased. In addition, silibinin-treated APP/PS1 transgenic mice had greater scores in the Morris Water Maze. Moreover, silibinin could increase the number of newly generated microglia, astrocytes, neurons, and neuronal precursor cells. Taken together, these data suggest that silibinin could act as a dual inhibitor of AChE and Aß peptide aggregation, therefore suggesting a therapeutic strategy for AD treatment.

Ginkgo biloba extract EGb761 protects against mitochondrial dysfunction in platelets and hippocampi in ovariectomized rats.

Using ovariectomized middle-aged rats to mimic the post-menopausal pathophysiological changes in women, we have previously demonstrated that estrogen withdrawal and age-related decrease in the functional reserve of mitochondria might co-operate to induce persistent mitochondrial dysfunction, which may be critical in inducing degenerative processes in the brain later in post-menopausal women. The standardized Ginkgo biloba extract EGb761 has long been considered a natural antioxidant. More recently it has also proposed to have direct protective effects on the mitochondria. In this work, effects of EGb761 on mitochondrial function in platelets and hippocampi of ovariectomized and sham-operated rats were investigated. It was found that EGb761 protected against the decrease of cytochrome c oxidase (COX) activity, mitochondrial ATP (adenosine-5'-triphosphate) content and mitochondrial glutathione (GSH) content in both platelets and hippocampi of ovariectomized rats, suggesting its peripheral and central effects against estrogen withdrawal-induced degeneration. In contrast, in sham-operated rats, EGb761 increased mitochondrial GSH content in platelets but failed to show similar effect on hippocampi, suggesting that EGb761 may help to enhance the functional reserve of mitochondria, but this effect was limited to the outside of the central nervous system. EGb761 displayed similar effects on platelets and hippocampi of ovariectomized rats but showed differential effects on platelets and hippocampi of sham-operated rats, possibly because estrogen withdrawal induced an increase of blood brain barrier (BBB) permeability. Therefore, while EGb761's effect may be limited to the outside of the nervous system under normal physiological conditions, EGb761 may be a potential protective agent against central neurodegeneration in post-menopausal women.

Protective effects of Ginkgo biloba extract (EGb761) and its constituents quercetin and ginkgolide B against beta-amyloid peptide-induced toxicity in SH-SY5Y cells.

Ginkgo biloba extract EGb761 has been shown to protect against beta-amyloid peptide (Abeta)-induced neurotoxicity but the specific mechanisms remain unclear. In the present study, effects of EGb761 and two of its constituents, quercetin and ginkgolide B, on the cytotoxic action of Abeta (1-42) were tested with human neuroblastoma SH-SY5Y cells. We found that EGb761 was able to block Abeta (1-42)-induced cell apoptosis, reactive oxygen species (ROS) accumulation, mitochondrial dysfunction and activation of c-jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt signaling pathways. Both quercetin and ginkgolide B may be involved in the inhibitory effects of EGb761 on JNK, ERK1/2 and Akt signaling pathways. Ginkgolide B also helped to improve mitochondrial functions but quercetin failed to show this effect. Additional experiments suggest that, protective effects of EGb761 against Abeta toxicity may be associated with its antioxidant and platelet activating factor (PAF) antagonist activities. Quercetin but not ginkgolide B is one of the constituents responsible for the antioxidant action of EGb761. Both quercetin and ginkgolide B may be involved in the PAF antagonist activity of EGb761. Overall, actions of individual EGb761 components provide further insights into direct mechanisms underlying the neuroprotective effects of EGb761.

Dosage effects of EGb761 on hydrogen peroxide-induced cell death in SH-SY5Y cells.

Standardized extract from the leaves of the Ginkgo biloba tree, labeled EGb761, is one of the most popular herbal supplements, taken for its multivalent properties. In this study, dosage effects of EGb761 on hydrogen peroxide (H(2)O(2))-induced apoptosis of human neuroblastoma SH-SY5Y cells were investigated. It was found that H(2)O(2)-induced apoptotic cell death in SH-SY5Y cells, which was revealed in DNA fragmentation, mitochondrial membrane potential depolarization, and activation of Akt, c-Jun N-terminal kinases (JNK) and caspase 3. Low doses of EGb761 (50-100 microg/ml) inhibited H(2)O(2)-induced cell apoptosis via inactivation of Akt, JNK and caspase 3 while high doses of EGb761 (250-500 microg/ml) enhanced H(2)O(2) toxicities via inactivation of Akt and enhancement of activation of JNK and caspase 3. Additional experiments revealed that H(2)O(2) decreased intracellular GSH content, which was also inhibited by low concentrations of EGb761 but enhanced after high concentrations of EGb761 treatment. This further suggests to us that dosage effects of EGb761 on apoptotic signaling proteins may be correlated with regulation of cell redox state. Therefore, treatment dosage may be one of the vital factors that determine the specific action of EGb761 on oxidative stress-induced cell apoptosis. To understand the mechanisms of dosage effects of EGb761 may have important clinical implications.

Effects of the aqueous extract of the Chinese medicine Danggui-Shaoyao-San on rat pineal melatonin synthesis.

OBJECTIVES: The purpose of this study is to investigate if the aqueous extract of the Chinese medicine Danggui-Shaoyao-San (DSS) can increase the plasma level of melatonin and enhance the function of the pineal gland of naturally aged rats. METHODS: The rats were treated with DSS at doses of 3ml or same volume of distilled water by oral administration at 11 p.m. for three weeks. The plasma level of melatonin were measured by radioimmunoassay. The function of pineal gland were measured through three parameters: pineal beta adrenergic receptor binding investigated by [3H]DHA binding; pineal expression of NAT mRNA detected by real-time RT-PCR; phosphorylation of CREB (P-CREB) and total level of CREB (T-CREB) measured by western blot analysis. RESULTS: DSS significantly increased melatonin level at night after oral administration for 3 weeks. By measurement of pineal [3H]DHA binding, it was found DSS improved the beta-adrenergic receptors binding in pineals. The stimulatory effect of DSS on the expression of NAT mRNA in the old rat pineal gland has been demonstrated in this study. Western blot analysis showed that DSS significantly increased phosphorylation of CREB. CONCLUSIONS: Our results indicate that a downstream pathway for DSS induction of melatonin synthesis in the rat pineal gland acts via cyclic AMP-dependent cascade and transcription mechanism.