Zhi-Hao Wang

Intracellular accumulation of tau protein is a defining feature of Alzheimer’s disease (AD) and is closely associated with episodic memory loss. In our previous report, we highlighted the high susceptibility of ventral hippocampal Calbindin1^- neurons in the dorsal part of ventral hippocampal CA1 (dvCA1^Calb1- neurons) to tau pathology in AD. However, it remains unclear whether and how dvCA1^Calb1+ neurons are also vulnerable during the chronic and progressive process of AD. In this study, we characterized dvCA1^Calb1+ neurons in terms of circuit connections and behavioral phenotypes under physiological conditions. Postmortem examination of AD patients’ brains and P301L mice revealed a preferential reduction of Calb1 in the dvCA1, accompanied by heightened susceptibility of the dvCA1^Calb1+ neurons to phospho-tau mislocalization. Mechanistically, C/EBPβ was found to bind to the promoter regions of CALB1, resulting in the inhibition of CALB1 transcription. Knockdown of Calb1 accelerated, while overexpression of Calb1 impeded the AD-like tau pathology in dvCA1^Calb1+ neurons. As tau accumulated, dvCA1^Calb1+ neurons lost their firing patterns, leading to contextual social memory deficits. Ursolic acid, by promoting the degradation of C/EBPβ, modified the C/EBPβ-Calb1 pathway, ultimately enhancing the resilience of dvCA1^Calb1+ neurons against tau pathology and improving contextual social memory in AD. Our findings underscore the critical role of the C/EBPβ-Calb1 pathway in controlling the susceptibility of dvCA1^Calb1+ neurons to tau pathology. Furthermore, targeting the C/EBPβ-Calb1 pathway and UA administration could be promising strategies for treating AD in the future.

Dietary capsaicin intake appears to affect the pathogenesis of Alzheimer’s disease (AD), while the underlying mechanisms remain unclear. Here, we found in human cohorts that moderate-to-high level of dietary capsaicin intake was associated with improved cognitive performance. Similarly, long-term oral capsaicin administration in male 5×FAD mice ameliorated AD-like pathologies and reshaped gut microbial composition. Gut microbiota transfer from capsaicin-treated mice produced similar effects of capsaicin intake. Moreover, capsaicin elevated the level of host 24(S)-hydroxycholesterol (24-HC), relating to the increase of gut Oscillibacter genus abundance. The 24-HC elevation enhanced microglial phagocytic activity in the brain, and inhibited proinflammatory factors production via liver x receptor β (LXRβ)-mediated transcriptional regulation. Finally, we observed elevation of 24-HC in plasma in AD patients with higher level of dietary capsaicin intake, which correlated with cognitive scores and plasma Aβ and p-tau biomarkers. These findings suggest the potential of capsaicin or capsaicin-rich diets in the prevention or treatment of AD and related diseases.

Accumulating research has demonstrated a significant association between early-life inflammation and behavioral disorders later in life. However, the effects of early-life inflammation on aggressive behavior in adulthood remain poorly understood. Here, we show that early-life inflammation induced by lipopolysaccharide (LPS) upregulated neuronal dynamin-related protein 1 (DRP1) and impaired mitochondrial function in medial prefrontal cortex (mPFC) of adult mice, thereby increasing aggressive behavior in adulthood. We further identify that CCAAT/enhancer binding protein β (C/EBPβ) is the transcription factor of Dnm1l, which was activated by an increased release of lysophosphatidic acid (LPA) induced by early-life inflammation. Moreover, the overproduction of LPA was due to a specific increase in astrocyte-secreted autotaxin (ATX). Specific knockdown of astrocytic ATX reduced early-life inflammation-induced aggression in wild-type mice, but not in Thy1-C/EBPβ transgenic mice. Remarkably, coenzyme Q10 decreased early-life inflammation-induced aggressive behavior in adult mice. Altogether, these findings provide new insights into the molecular mechanisms by which early inflammation promotes aggressive behavior in adulthood.

Early life experience modulates resilience to stress in later life. Previous research implicated maternal care as a key mediator of behavioral responses to the adversity in adolescence, but details of molecular mechanisms remain elusive. Here, we show social stress activates transcription factor C/EBPβ in mPFC neurons of adolescent mice, which transcriptionally upregulates Dnm1l and promotes mitochondrial dysfunction, thereby conferring stress susceptibility in adolescent mice. Moreover, different maternal separation differentially regulates adolescent stress susceptibility. Mechanistically, this differential effect depends on maternal behavior-stimulated IGF-1, which inhibits neuronal C/EBPβ through mTORC1-induced C/EBPβ-LIP translation. Furthermore, we identify maternal behavior-stimulated IGF-1 is mainly released from mPFC microglia. Notably, increased maternal care under an environmental enrichment condition or maternal behavior impairment induced by repeated MPOA^Esr1+ cells inhibition in dams prevents or promotes stress susceptibility via microglial-to-neuronal IGF-1-C/EBPβ-DRP1 signaling. In this work, these findings have unveiled molecular mechanisms by which maternal behavior promotes stress resilience in adolescents.

Background: Disrupted hippocampal functions and progressive neuronal loss represent significant challenges in the treatment of Alzheimer's disease (AD). How to achieve the improvement of pathological progression and effective neural regeneration to ameliorate the intracerebral dysfunctional environment and cognitive impairment is the goal of the current AD therapy.

Introduction: Alzheimer’s disease (AD) is the most prevalent neurodegenerative disease characterized by extracellular senile plaques including amyloid-β peptides and intracellular neurofibrillary tangles consisting of abnormal Tau. Depression is one of the most common neuropsychiatric symptoms in AD, and clinical evidence demonstrates that depressive symptoms accelerate the cognitive deficit of AD patients. However, the underlying molecular mechanisms of depressive symptoms present in the process of AD remain unclear.Methods: Depressive-like behaviors and cognitive decline in hTau mice were induced by chronic restraint stress (CRS). Computational prediction and molecular experiments supported that an asparagine endopeptidase (AEP)-derived Tau fragment, Tau N368 interacts with peroxisome proliferator-activated receptor delta (PPAR-δ). Further behavioral studies investigated the role of Tau N368-PPAR-δ interaction in depressive-like behaviors and cognitive declines of AD models exposed to CRS.Results: We found that mitochondrial dysfunction was positively associated with depressive-like behaviors and cognitive deficits in hTau mice. Chronic stress increased Tau N368 and promoted the interaction of Tau N368 with PPAR-δ, repressing PPAR-δ–mediated transactivation in the hippocampus of mice. Then we predicted and identified the binding sites of PPAR-δ. Finally, inhibition of AEP, clearance of Tau N368 and pharmacological activation of PPAR-δ effectively alleviated CRS-induced depressive-like behaviors and cognitive decline in mice.Conclusion: These results demonstrate that Tau N368 in the hippocampus impairs mitochondrial function by suppressing PPAR-δ, facilitating the occurrence of depressive-like behaviors and cognitive decline. Therefore, our findings may provide new mechanistic insight in the pathophysiology of depression-like phenotype in mouse models of Alzheimer’s disease.

Alzheimer’s disease (AD) is a leading cause of dementia, impacting millions worldwide. However, its complex neuropathologic features and heterogeneous pathophysiology present significant challenges for diagnosis and treatment. To address the urgent need for early AD diagnosis, this review focuses on surface-enhanced Raman scattering (SERS)-based biosensors, leveraging the excellent optical properties of nanomaterials to enhance detection performance. These highly sensitive and noninvasive biosensors offer opportunities for biomarker-driven clinical diagnostics and precision medicine. The review highlights various types of SERS-based biosensors targeting AD biomarkers, discussing their potential applications and contributions to AD diagnosis. Specific details about nanomaterials and targeted AD biomarkers are provided. Furthermore, the future research directions and challenges for improving AD marker detection using SERS sensors are outlined.

Depression, one of the most common causes of disability, has a high prevalence rate in patients with metabolic syndrome. Type 2 diabetes patients are at an increased risk for depression. However, the molecular mechanism coupling diabetes to depressive disorder remains largely unknown. Here we found that the neuroinflammation, associated with high-fat diet (HFD)-induced diabetes and obesity, activated the transcription factor CCAAT/enhancer binding protein β (C/EBPβ) in hippocampal neurons. This factor repressed brain-derived neurotrophic factor (BDNF) expression and caused depression-like behaviors in male mice. Besides, the loss of C/EBPβ expression in C/EBPβ heterozygous knockout male mice attenuated HFD-induced depression-like behaviors, whereas Thy1-C/EBPβ transgenic male mice (overexpressing C/EBPβ) showed depressive behaviors after a short-term HFD. Furthermore, HFD impaired synaptic plasticity and decreased surface expression of glutamate receptors in the hippocampus of wild-type (WT) mice, but not in C/EBPβ heterozygous knockout mice. Remarkably, the anti-inflammatory drug aspirin strongly alleviated HFD-elicited depression-like behaviors in neuronal C/EBPβ transgenic mice. Finally, the genetic delivery of BDNF or the pharmacological activation of the BDNF/TrkB signaling pathway by 7,8-dihydroxyflavone reversed anhedonia in a series of behavioral tests on HFD-fed C/EBPβ transgenic mice. Therefore, our findings aim to demonstrate that the inflammation-activated neuronal C/EBPβ promotes HFD-induced depression by diminishing BDNF expression.

Brain derived neurotrophic factor (BDNF) has multiple biological functions which are mediated by the activation of two receptors, tropomyosin receptor kinase B (TrkB) receptor and the p75 neurotrophin receptor, involving in physiological and pathological processes throughout life. The diverse presence and activity of BDNF indicate its potential role in the pathogenesis, progression and treatment of both neurological and psychiatric disorders. This review is to provide a comprehensive assessment of the current knowledge and future directions in BDNF-associated research in the central nervous system (CNS), with an emphasis on the physiological and pathological functions of BDNF as well as its potential treatment effects in CNS diseases, including depression, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, multiple sclerosis, and cerebral ischemic stroke.