Background: Alzheimer’s disease (AD) is the most common form of neurodegenerative dementia among the elderly. Excitotoxicity has been implicated as playing a dominant role in AD, especially related to the hyperactivation of excitatory neurons. Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin-dependent kinase and involved in the pathogenesis of AD, but the roles and mechanisms of DAPK1 in excitotoxicity in AD are still uncertain. Objective: We mainly explored the underlying mechanisms of DAPK1 involved in the excitotoxicity of AD and its clinical relevance. Methods: Differentiated SH-SY5Y human neuroblastoma cells, PS1 V97 L transgenic mice, and human plasma samples were used. Protein expression was assayed by immunoblotting, and intracellular calcium and neuronal damage were analyzed by flow cytometry. Plasma DAPK1 was measured by ELISA. Results: We found that DAPK1 was activated after amyloid-β oligomers (AβOs) exposure in differentiated SH-SY5Y cells. Besides, we found the phosphorylation of GluN2B subunit at Ser1303 was increased, which contributing to excitotoxicity and Ca2+ overload in SH-SY5Y cells. Inhibiting DAPK1 activity, knockdown of DAPK1 expression, and antagonizing GluN2B subunits could effectively prevent AβOs-induced activation of GluN2B subunit, Ca2+ overload, and neuronal apoptosis. Additionally, we found that DAPK1 was elevated in the brain of AD transgenic mouse and in the plasma of AD patients. Conclusion: Our finding will help to understand the mechanism of DAPK1 in the excitotoxicity in AD and provide a reference for the diagnosis and therapy of AD.

Indole is a microbial metabolite produced by the gut microbiota through the degradation of dietary tryptophan, known for its well‐established anti‐inflammatory and antioxidant properties. In this study, we collected fecal samples from mice fed a high‐fat diet (HFD) and those on a standard diet (SD), then conducted 16S rRNA sequencing to analyze their gut microbiota. The analysis revealed distinct differences in the dominant bacterial species between the two groups, with a significant decrease in indole‐producing probiotics in the HFD mice compared to the SD group. Then we administered oral indole treatment to male C57BL/6J mice with HFD‐induced NAFLD and observed a significant improvement in hepatic steatosis and inflammation. Notably, indole alleviated the HFD‐induced decline in serum Angiotensin‐(1–7) [Ang‐(1–7)] levels and Angiotensin‐Converting Enzyme 2 (ACE2) expression. To further investigate the role of indole and ACE2 in NAFLD, we conducted experiments using ACE2 knockout (ACE2KO) mice that were also induced with HFD‐induced NAFLD and treated with indole. Interestingly, the protective effects of indole were compromised in the absence of ACE2. In HepG2 cells, indole similarly stimulated ACE2 expression and, in an ACE2‐dependent manner, reduced ROS generation, maintained mitochondrial membrane potential stability, and increased SIRT3 expression. In summary, our results highlight the formation of a biologically active gut‐liver axis between the gut microbiota and the liver through the tryptophan metabolite indole, which mitigates NAFLD in an ACE2‐dependent manner. Elevating dietary tryptophan and increasing indole levels may represent an effective approach for preventing and treating NAFLD.

Early identification of pre-diabetes provides an opportunity for intervention and treatment to delay its progression to type 2 diabetes mellitus (T2DM). We aimed to identify the biomarkers of impaired glucose tolerance (IGT) through bioinformatics analysis. The GSE76896 dataset, including non-diabetic (ND), IGT, and T2DM clinical samples, was deeply analyzed to identify 309 Co-DEGs for IGT and T2DM. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that inflammatory responses and the PI3K-AKT signaling pathway are important patho-physiological features of IGT and T2DM. Protein–protein interaction (PPI) network analysis and cytoHubba technolgy identified seven hub genes: namely, CCL2, CXCL1, CXCL8, EDN1, FGF13, MMP1, and NGF. The expression and ROC curves of these hub genes were validated using the GSE38642 dataset. Through an immunofluorescence assay, we found that the expression of FGF13 in islets of mice in the HFD and T2DM groups was significantly lower than in the control group. Similarly, the level of FGF13 in the sera of IGT and T2DM patients was lower than that in the healthy group. Together, these results suggest that FGF13 can be treated as a novel biomarker of IGT, which may provide new targets for the diagnosis and treatment of pre-diabetes and T2DM.

Background: Alzheimer disease (AD) is the most common neurodegenerative disorder leading to dementia in the elderly worldwide. Wnt signaling participates in multiple aspects of cellular function, and contributes to synapse formation, synaptic activity and neurogenesis in the brain, and dysfunction of Wnt signaling may aggravate the pathogenesis and progression of AD. Wnt2b has been studied in cancers or tumor‐related diseases, while the roles of Wnt2b in AD is still unknown. Wnt2b is also characterized as a mitochondria‐expressed protein which shuttles between mitochondria and the nucleus, and mitochondrial dysfunction contributes to the development and progression of the pathological process that underlies AD, especially at the early stage. This study investigated the relationship between plasma Wnt2b levels and AD, and explored the effect of Wnt2b on mitochondrial dysfunction in AD.Method: Normal cognitive (NC) and AD subjects, AD transgenic mice and in vitro model were used to investigated the roles of Wnt2b in abnormalities in canonical Wnt signaling and mitochondria in AD. RT‐qPCR, immunoblotting and immunofluorescence analysis were performed to assay canonical Wnt sign aling. Mitochondrial structure was analyzed by electron microscopy. Flow cytometry was used to examine the intracellular calcium and neuronal apoptosis.Result: In this study, we found plasma Wnt2b levels were lower in AD patients than NC subjects and positively correlated with cognitive performance (Figure 1). Similarly, Wnt2b was reduced in the hippocampus of AD mice and in vitro models (Figure 1). Next, Wnt2b overexpression and recombinant Wnt2b was used to endogenously (Figure 2) and exogenously (Figure 3) upregulate Wnt2b levels. Upregulation of Wnt2b could effectively prevent downregulation of canonical Wnt signaling, mitochondrial dysfunction in in vitro AD models. Subsequently, intracellular calcium overload and neuronal damage were ameliorated.Conclusion: Our study highlights that Wnt2b decline is associated with cognitive impairment in AD, and Our findings may advance the understanding of the importance of Wnt family in AD, and we propose that Wnt2b might be a potential diagnostic indicator and therapeutic target for AD.