Using Stems to Bear Fruit: Deciphering the Role of Alzheimer's Disease Risk Loci in Human-Induced Pluripotent Stem Cell-Derived Microglia

A Pair of Epimers of Lignan Alleviate Neuroinflammatory Effects by Modulating iNOS/COX-2 and MAPK/NF-κB Signaling Pathways

Neuroinflammation is a causative factor in neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis. Previous studies have shown that Artemisia mongolica has anti-inflammatory properties. Aschantin (AM3) has been shown to have anti-inflammatory effects. However, the mechanism of AM3 and its epimer epi-aschantin (AM2) remains controversial. Therefore, the present study explored the mechanism of neuroinflammation by AM2 and AM3 and attempted to reveal the relationship between the structure of AM2 and AM3 and anti-neuroinflammatory activity. We isolated for the first time 12 lignans from A. mongolica that inhibited NO content at 10 μM in LPS-stimulated BV2 cells. Among them, epi-aschantin (AM2) and Aschantin (AM3) showed significant inhibition in NO screening. With further studies, we found that both AM2 and AM3 effectively inhibited the overproduction of NO, PGE2, IL-6, TNF-α and MCP-1, as well as the overexpression of COX-2 and iNOS. Mechanistic studies have shown AM2 and AM3 significantly inhibited the phosphorylation of ERK, JNK and P-38 in the MAPK signaling pathway and p-IκBα,p-p65 and blocked p65 entry into the nucleus. The results suggested that the pair of epimers (AM2 and AM3) can be used as potential therapeutic agents in the treatment of various brain disorders and that structural differences do not differ in anti-neuroinflammatory effects.

Single Nuclei Transcriptomics Reveals Obesity-Induced Endothelial and Neurovascular Dysfunction: Implications for Cognitive Decline

Obesity confers risk for cardiovascular disease and vascular dementia. However, genomic alterations modulated by obesity in endothelial cells in the brain and their relationship to other neurovascular unit (NVU) cells are unknown. We performed single nuclei RNA sequencing (snRNAseq) of the NVU (endothelial cells, astrocytes, microglia, and neurons) from the hippocampus of obese (ob/ob) and wild-type (WT) male mice to characterize obesity-induced transcriptomic changes in a key brain memory center and assessed blood-brain barrier permeability (BBB) by gadolinium-enhanced magnetic resonance imaging (MRI). Ob/ob mice displayed obesity, hyperinsulinemia, and impaired glucose tolerance. snRNAseq profiled 14 distinct cell types and 32 clusters within the hippocampus of ob/ob and WT mice and uncovered differentially expressed genes (DEGs) in all NVU cell types, namely, 4462 in neurons, 1386 in astrocytes, 125 in endothelial cells, and 154 in microglia. Gene ontology analysis identified important biological processes such as angiogenesis in endothelial cells and synaptic trafficking in neurons. Cellular pathway analysis included focal adhesion and insulin signaling, which were common to all NVU cell types. Correlation analysis revealed significant positive correlations between endothelial cells and other NVU cell types. Differentially expressed long non-coding RNAs (lncRNAs) were observed in cells of the NVU-affecting pathways such as TNF and mTOR. BBB permeability showed a trend toward increased signal intensity in ob/ob mice. Taken together, our study provides in-depth insight into the molecular mechanisms underlying cognitive dysfunction in obesity and may have implications for therapeutic gene targeting.

Preclinical translational platform of neuroinflammatory disease biology relevant to neurodegenerative disease

Neuroinflammation is a key driver of neurodegenerative disease, however the tools available to model this disease biology at the systems level are lacking. We describe a translational drug discovery platform based on organotypic culture of murine cortical brain slices that recapitulate disease-relevant neuroinflammatory biology. After an acute injury response, the brain slices assume a chronic neuroinflammatory state marked by transcriptomic profiles indicative of activation of microglia and astrocytes and loss of neuronal function. Microglia are necessary for manifestation of this neuroinflammation, as depletion of microglia prior to isolation of the brain slices prevents both activation of astrocytes and robust loss of synaptic function genes. The transcriptomic pattern of neuroinflammation in the mouse platform is present in published datasets derived from patients with amyotrophic lateral sclerosis, Huntington's disease, and frontotemporal dementia. Pharmacological utility of the platform was validated by demonstrating reversal of microglial activation and the overall transcriptomic signature with transforming growth factor-β. Additional anti-inflammatory targets were screened and inhibitors of glucocorticoid receptors, COX-2, dihydrofolate reductase, and NLRP3 inflammasome all failed to reverse the neuroinflammatory signature. Bioinformatics analysis of the neuroinflammatory signature identified protein tyrosine phosphatase non-receptor type 11 (PTPN11/SHP2) as a potential target. Three structurally distinct inhibitors of PTPN11 (RMC-4550, TN0155, IACS-13909) reversed the neuroinflammatory disease signature. Collectively, these results highlight the utility of this novel neuroinflammatory platform for facilitating identification and validation of targets for neuroinflammatory neurodegenerative disease drug discovery.