The MAO Inhibitor Tranylcypromine Alters LPS- and Aβ-Mediated Neuroinflammatory Responses in Wild-type Mice and a Mouse Model of AD

Mechanisms of Transsynaptic Degeneration in the Aging Brain

A prominent feature in many neurodegenerative diseases involves the spread of the pathology from the initial site of damage to anatomically and functionally connected regions of the central nervous system (CNS), referred to as transsynaptic degeneration (TSD). This review covers the possible mechanisms of both retrograde and anterograde TSD in various age-related neurodegenerative diseases, including synaptically and glial mediated changes contributing to TDS and their potential as therapeutic targets. This phenomenon is well documented in clinical and experimental studies spanning various neurodegenerative diseases and their respective models, with a significant emphasis on the visual pathway, to be explored herein. With the increase in the aging population and subsequent rise in age-related neurodegenerative diseases, it is crucial to understand the underlying mechanisms of.

A systematic review for the development of Alzheimer's disease in in vitro models: a focus on different inducing agents

Alzheimer's disease (AD) is the most common progressive neurodegenerative disease and is associated with dementia. Presently, various chemical and environmental agents are used to induce in-vitro models of Alzheimer disease to investigate the efficacy of different therapeutic drugs. We screened literature from databases such as PubMed, ScienceDirect, and Google scholar, emphasizing the diverse targeting mechanisms of neuro degeneration explored in in-vitro models. The results revealed studies in which different types of chemicals and environmental agents were used for in-vitro development of Alzheimer-targeting mechanisms of neurodegeneration. Studies using chemically induced in-vitro AD models included in this systematic review will contribute to a deeper understanding of AD. However, none of these models can reproduce all the characteristics of disease progression seen in the majority of Alzheimer's disease subtypes. Additional modifications would be required to replicate the complex conditions of human AD in an exact manner. In-vitro models of Alzheimer's disease developed using chemicals and environmental agents are instrumental in providing insights into the disease's pathophysiology; therefore, chemical-induced in-vitro AD models will continue to play vital role in future AD research. This systematic screening revealed the pivotal role of chemical-induced in-vitro AD models in advancing our understanding of AD pathophysiology and is therefore important to understand the potential of these chemicals in AD pathogenesis.

Viscosalactone B, a natural LSD1 inhibitor, inhibits proliferation in vitro and in vivo against prostate cancer cells

Lysine-specific demethylase 1 (LSD1) has been a promising target to treat prostate cancer, and discovery of novel LSD1 inhibitors would have great clinical significance. In this work, viscosalactone B was first identified as a novel LSD1 inhibitor. Viscosalactone B isolated from Withania Somnifera displayed antiproliferative activity against PC3, DU145, C42B, PC3/MDVR, DU145/MDVR, and C42B/MDVR cells with IC₅₀ values of 1.17, 0.72, 3.86, 2.06, 0.96 and 1.15 μM, respectively. In comparison, it was a selective LSD1 inhibitor with an IC₅₀ value of 970.27 nM and could induce a significant accumulation of LSD1 substrates H3K9me1, H3K9me2, and H3K4me1 in a concentration-dependent manner in DU145 cells. According to docking studies, it formed hydrogen bonds with the Thr11, Lys14, and Arg8 residues of LSD1. Importantly, while it displayed potent antitumor efficacy in vivo, it did not show obvious cytotoxicity on the major organs of nude mice. Therefore, viscosalactone B, as a novel LSD1 inhibitor, is a potential candidate that can be used for the treatment of prostate cancer in clinics.

Inhibiting EGFR/HER-2 ameliorates neuroinflammatory responses and the early stage of tau pathology through DYRK1A

The FDA-approved EGFR/HER2 inhibitor varlitinib inhibits tumor growth and is used in cancer treatment. However, the neuroinflammatory response associated with EGFR/HER2 and its underlying mechanism have not been elucidated. This study evaluates the impact of varlitinib on LPS- and tau-mediated neuroinflammatory responses for the first time. In BV2 microglial cells, varlitinib reduced LPS-stimulated il-1β and/or inos mRNA levels and downstream AKT/FAK/NF-kB signaling. Importantly, varlitinib significantly diminished LPS-mediated microglial nlrp3 inflammasome activation in BV2 microglial cells. In primary astrocytes, varlitinib downregulated LPS-evoked astroglial il-1β mRNA levels, AKT signaling, and nlrp3 inflammasome activation. In LPS-treated wild-type mice, varlitinib significantly reduced LPS-stimulated glial activation and IL-1β/NLRP3 inflammasome formation. Moreover, varlitinib significantly reduced micro- and astroglial activation and tau hyperphosphorylation in 3-month-old tau-overexpressing PS19 mice by downregulating tau kinase DYRK1A levels. However, in 6-month-old tau-overexpressing PS19 mice, varlitinib only significantly diminished astroglial activation and tau phosphorylation at Thr212/Ser214. Taken together, our findings suggest that varlitinib has therapeutic potential for LPS- and tau-induced neuroinflammatory responses and the early stages of tau pathology.

A monoamine oxidase B inhibitor ethyl ferulate suppresses microglia-mediated neuroinflammation and alleviates ischemic brain injury

Microglia are the resident macrophages in the brain, which play a critical role in post-stroke neuroinflammation. Accordingly, targeting neuroinflammation could be a promising strategy to improve ischemic stroke outcomes. Ethyl ferulate (EF) has been confirmed to possess anti-inflammatory properties in several disease models, including acute lung injury, retinal damage and diabetes-associated renal injury. However, the effects of EF on microglial activation and the resolution of post-stroke neuroinflammation remains unknown. Here, we found that EF suppressed pro-inflammatory response triggered by lipopolysaccharide (LPS) stimulation in primary microglia and BV2 cell lines, as well as post-stroke neuroinflammation in an in vivo transient middle cerebral artery occlusion (tMCAO) stroke model in C57BL/6 mice, consequently ameliorating ischemic brain injury. Furthermore, EF could directly bind and inhibit the activity of monoamine oxidase B (MAO-B) to reduce pro-inflammatory response. Taken together, our study identified a MAO-B inhibitor, Ethyl ferulate, as an active compound with promising potentials for suppressing post-stroke neuroinflammation.

Nilotinib modulates LPS-induced cognitive impairment and neuroinflammatory responses by regulating P38/STAT3 signaling

BACKGROUND

In chronic myelogenous leukemia, reciprocal translocation between chromosome 9 and chromosome 22 generates a chimeric protein, Bcr-Abl, that leads to hyperactivity of tyrosine kinase-linked signaling transduction. The therapeutic agent nilotinib inhibits Bcr-Abl/DDR1 and can cross the blood-brain barrier, but its potential impact on neuroinflammatory responses and cognitive function has not been studied in detail.

METHODS

The effects of nilotinib in vitro and in vivo were assessed by a combination of RT-PCR, real-time PCR, western blotting, ELISA, immunostaining, and/or subcellular fractionation. In the in vitro experiments, the effects of 200 ng/mL LPS or PBS on BV2 microglial cells, primary microglia or primary astrocytes pre- or post-treated with 5 µM nilotinib or vehicle were evaluated. The in vivo experiments involved wild-type mice administered a 7-day course of daily injections with 20 mg/kg nilotinib (i.p.) or vehicle before injection with 10 mg/kg LPS (i.p.) or PBS.

RESULTS

In BV2 microglial cells, pre- and post-treatment with nilotinib altered LPS-induced proinflammatory/anti-inflammatory cytokine mRNA levels by suppressing AKT/P38/SOD2 signaling. Nilotinib treatment also significantly downregulated LPS-stimulated proinflammatory cytokine levels in primary microglia and primary astrocytes by altering P38/STAT3 signaling. Experiments in wild-type mice showed that nilotinib administration affected LPS-mediated microglial/astroglial activation in a brain region-specific manner in vivo. In addition, nilotinib significantly reduced proinflammatory cytokine IL-1β, IL-6 and COX-2 levels and P38/STAT3 signaling in the brain in LPS-treated wild-type mice. Importantly, nilotinib treatment rescued LPS-mediated spatial working memory impairment and cortical dendritic spine number in wild-type mice.

CONCLUSIONS

Our results indicate that nilotinib can modulate neuroinflammatory responses and cognitive function in LPS-stimulated wild-type mice.

Dendrobium Nobile Lindl. Alkaloid Suppresses NLRP3-Mediated Pyroptosis to Alleviate LPS-Induced Neurotoxicity

Alzheimer’s disease (AD) is a neurodegenerative disorder recognized as a global public health priority. Although available treatments temporarily relieve the symptoms, they could not prevent the progression of cognitive decline. Natural compounds have been rich sources for drug discovery. Dendrobium nobile Lindl. alkaloid (DNLA) is the main active compound in Dendrobium nobile Lindl, a traditional Chinese herbal medicine. Recent studies indicated that DNLA produced neuroprotection. However, the mechanisms underlying DNLA-generated neuroprotection remain unknown. To investigate neuroprotection and the underlying mechanisms of DNLA, mouse hippocampus injection of lipopolysaccharide (LPS)-induced neuronal damage was performed. DNLA protected hippocampus neurons and working memory disorder against LPS-induced neurotoxicity. In addition, DNLA suppressed cell undergoing membrane lysis and cell swelling and inhibited the essential mediator of pyroptosis GSDMD-N expressions. Furthermore, DNLA-mediated neuroprotection was dependent on the inhibition of NLRP3 inflammasome activation, as evidenced by the fact that DNLA reduced pro-inflammatory factor (IL-18 and IL-1β) production and inhibited the expression of related proteins. DNLA-exerted neuroprotection against LPS-induced neuronal damage, and cognitive impairment was not observed in NLRP3 knockout mice. Together, this study suggested that DNLA attenuated NLRP3-mediated pyroptosis to generate neuroprotection against LPS-induced neuronal damage and cognitive impairment.