NLRP3/Caspase-1-Mediated Pyroptosis of Astrocytes Induced by Antipsychotics Is Inhibited by a Histamine H1 Receptor-Selective Agonist

Olanzapine attenuates amyloid-β-induced microglia-mediated progressive neurite lesions

The accumulation of amyloid-β (Aβ) in the brain is the first pathological mechanism to initiate Alzheimer's disease (AD) pathogenesis. However, the precise role of Aβ in the disease progression remains unclear. Through decades of research, prolonged inflammation has emerged as an important core pathology in AD. Previously, a study has demonstrated the neurotoxic effect of Aβ-induced neuroinflammation in neuron-glia co-culture at 72 h. Here, we hypothesise that initial stage Aβ may trigger microglial inflammation, synergistically contributing to the progression of neurite lesions relevant to AD progression. In the present study, we aimed to determine whether olanzapine, an antipsychotic drug possessing anti-inflammatory properties, can ameliorate Aβ-induced progressive neurite lesions. Our study reports that Aβ induces neurite lesions with or without inflammatory microglial cells in vitro. More intriguingly, the present study revealed that Aβ exacerbates neurite lesions in synergy with microglia. Moreover, the time course study revealed that Aβ promotes microglia-mediated neurite lesions by eliciting the secretion of pro-inflammatory cytokines. Furthermore, our study shows that olanzapine at lower doses prevents Aβ-induced microglia-mediated progressive neurite lesions. The increase in pro-inflammatory cytokines induced by Aβ is attenuated by olanzapine administration, associated with a reduction in microglial inflammation. Finally, this study reports that microglial senescence induced by Aβ was rescued by olanzapine. Thus, our study provides the first evidence that 1 µM to 5 µM of olanzapine can effectively prevent Aβ-induced microglia-mediated progressive neurite lesions by modulating microglial inflammation. These observations reinforce the potential of targeting microglial remodelling to slow disease progression in AD.

El Gendy A, Serag A, Abd El-Fadeal NM, Abdel-Karim RI, Mostafa MM, El-Sheikh DH, Zayed MA. Acacia saligna extract alleviates quetiapine-induced sexual toxicity in male albino rats: Insights from UPLC-MS/MS metabolite profiling, structural and PI3K/NF-κB pathway assessments

Background

Quetiapine (QET) abuse has increased due to its anxiolytic and hedonic effects, necessitating protective adjunct treatments. Acacia saligna (A. saligna) flowers, used in traditional medicine, have potential health benefits.

Aim

To investigate the protective role of A. saligna flower extract against QET-induced sexual toxicity, and to elucidate the possible underlying mechanisms through metabolomic and physiological studies.

Methods

A. saligna extract was subjected to metabolite profiling via High-Resolution Ultra-Performance Liquid Chromatography-Mass Spectrometry (UPLC-ESI-qTOF-MS). Forty-eight adult male albino rats were assigned into six groups for 30 days. The intracavernosal pressure (ICP), semen, biochemical, hormonal, histological, genetic and Western blot (WB) analyses were determined.

Results

A. saligna extract is rich in phenolic compounds, flavonoids, tannins, and unsaturated fatty acids. QET significantly decreased ICP and negatively affected semen parameters. A. saligna mitigated decreased sperm motility and ameliorated overexpressed proinflammatory genes in QET-55 group. A. saligna ameliorated the reduction of the antioxidant biomarkers, testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), concurrent with downregulation of the nuclear factor kappa B (NF-κB) protein. A. saligna counteracted the disrupted testicular and prostatic structures revealed by histological examination.

Conclusion

The extract from A. saligna, which contains a high concentration of antioxidants and anti-inflammatory chemicals, effectively mitigates sexual toxicity caused by QET. This study provided the first known explanation of the hypothesized processes behind the protective properties of A. saligna through biological, biochemical, and histological parameters. The results emphasize the potential of A. saligna as a safeguarding agent against drug-induced sexual toxicity.

Genome Mining Leads to Diverse Sesquiterpenes with Anti-inflammatory Activity from an Arctic-Derived Fungus

With the advancement of bioinformatics, the integration of genome mining with efficient separation technology enables the discovery of a greater number of novel bioactive compounds. The deletion of the key gene responsible for triterpene cyclase biosynthesis in the polar strain Eutypella sp. D-1 instigated metabolic shunting, resulting in the activation of dormant genes and the subsequent production of detectable, new compounds. Fifteen sesquiterpenes were isolated from the mutant strain, with eight being new compounds. The structural elucidation of these compounds was obtained through a combination of HRESIMS, NMR spectroscopy, and ECD calculations, revealing six distinct skeleton types. Compound 7 possessed a unique skeleton of 5/10 macrocyclic ether structure. Based on the gene functions and newly acquired secondary metabolites, the metabolic shunting pathway in the mutant strain was inferred. Compounds 6, 8, 11, 14, and 15 exhibited anti-inflammatory effects without cytotoxicity through the release of nitric oxide from lipopolysaccharide-stimulated RAW264.7 cells. Notably, acorane-type sesquiterpene 8 inhibited nitric oxide production and modulated the MAPK and NLRP3/caspase-1 signaling pathways. Compound 8 also alleviated the CuSO4-induced systemic neurological inflammation symptoms in a transgenic fluorescent zebrafish model.

Influence of the brain‑gut axis on neuroinflammation in cerebral ischemia‑reperfusion injury (Review)

Stroke, a debilitating cerebrovascular ailment, poses significant threats to human life and health. The intricate interplay between the gut‑brain‑microbiota axis (GBMA) and cerebral ischemia‑reperfusion has increasingly become a focal point of scientific exploration, emerging as a pivotal research avenue in stroke pathophysiology. In the present review, the authors delved into the nexus between the GBMA and neuroinflammation observed post‑stroke. The analysis underscored the pivotal roles of histone deacetylase 3 and neutrophil extracellular traps subsequent to stroke incidents. The influence of gut microbial compositions and their metabolites, notably short‑chain fatty acids and trimethylamine N‑oxide, on neuroinflammatory processes, was further elucidated. The involvement of immune cells, especially regulatory T‑cells, and the intricate signaling cascades including cyclic GMP‑AMP synthase/stimulator of interferon genes/Toll‑like receptor, further emphasized the complex regulatory mechanisms of GBMA in cerebral ischemia/reperfusion injury (CI/RI). Collectively, the present review offered a comprehensive perspective on the metabolic, immune and inflammatory modulations orchestrated by GBMA, augmenting the understanding of its role in neuroinflammation following CI/RI.

The role of NLRP6 in the development and progression of neurological diseases

The nervous system possesses the remarkable ability to undergo changes in order to store information; however, it is also susceptible to damage caused by invading pathogens or neurodegenerative processes. As a member of nucleotide-binding oligomerization domain-like receptor (NLR) family, the NLRP6 inflammasome serves as a cytoplasmic innate immune sensor responsible for detecting microbe-associated molecular patterns. Upon activation, NLRP6 can recruit the adapter protein apoptosis-associated speck-like protein (ASC) and the inflammatory factors caspase-1 or caspase-11. Consequently, inflammasomes are formed, facilitating the maturation and secretion of pro-inflammatory cytokines such as inflammatory factors-18 (IL-18) and inflammatory factors-1β (IL-1β). Precise regulation of NLRP6 is crucial for maintaining tissue homeostasis, as dysregulated inflammasome activation can contribute to the development of various diseases. Furthermore, NLRP6 may also play a role in the regulation of extraintestinal diseases. In cells of the brain, such as astrocytes and neurons, NLRP6 inflammasome are also present. Here, the assembly and subsequent activation of caspase-1 mediated by NLRP6 contribute to disease progression. This review aims to discuss the structure and function of NLRP6, explain clearly the mechanisms that induce and activate NLRP6, and explore its role within the central and peripheral nervous system.

Histamine deficiency deteriorates LPS-induced periodontal diseases in a murine model via NLRP3/Caspase-1 pathway

Histamine is a versatile biogenic amine, generated by the unique enzyme histidine decarboxylase (Hdc). Accumulating evidence has proven that histamine plays important roles in numerous biological and pathophysiological processes. However, the role and mechanism of Hdc/Histamine signaling in periodontal diseases remain unclear. In our current study, the concentration of histamine increased in the serum, and Hdc gene expression was upregulated in the gingiva of WT mice with LPS-induced periodontal inflammation. With Hdc-GFP mice, we identified that Hdc/GFP in the periodontium was expressed in CD11b⁺ myeloid cells, rather than in tryptase-positive mast cells. Hdc-expressing CD11b⁺Gr-1⁺ neutrophils significantly increased in the peripheral blood of Hdc-GFP mice one day after LPS injection. Lack of histamine in Hdc^-/- mice not only promoted the activation and infiltration of more CD11b⁺ cells into the peripheral blood but also upregulated mRNA expression levels of IL-1β, IL-6, MCP-1and MMP9 in the gingiva compared to WT mice one day after LPS stimulation. 28 days after LPS treatment, we observed that Hdc^-/- mice exhibited more alveolar bone loss and more osteoclasts than WT mice, which was slightly ameliorated by the administration of exogenous histamine. In vivo and in vitro mechanistic studies revealed that the mRNA expression levels of proinflammatory cytokines and protein levels of NLRP3, Caspase-1, and cleaved-Caspase-1 were upregulated after blocking histamine receptor 1 and 2, especially histamine receptor 1. Taken together, CD11b⁺Gr-1⁺ neutrophils are the predominant Hdc-expressing sites in periodontal inflammation, and deficiency of endogenous histamine in Hdc^-/- mice exacerbates the destruction of the periodontium. Disruption of the histamine/H₁R/H₂R axis aggravates the inflammatory immune response via NLRP3/Casapse-1 pathway.

The role of hypothalamic endoplasmic reticulum stress in schizophrenia and antipsychotic-induced weight gain: A narrative review

Schizophrenia (SCZ) is a serious mental illness that affects 1% of people worldwide. SCZ is associated with a higher risk of developing metabolic disorders such as obesity. Antipsychotics are the main treatment for SCZ, but their side effects include significant weight gain/obesity. Despite extensive research, the underlying mechanisms by which SCZ and antipsychotic treatment induce weight gain/obesity remain unclear. Hypothalamic endoplasmic reticulum (ER) stress is one of the most important pathways that modulates inflammation, neuronal function, and energy balance. This review aimed to investigate the role of hypothalamic ER stress in SCZ and antipsychotic-induced weight gain/obesity. Preliminary evidence indicates that SCZ is associated with reduced dopamine D2 receptor (DRD2) signaling, which significantly regulates the ER stress pathway, suggesting the importance of ER stress in SCZ and its related metabolic disorders. Antipsychotics such as olanzapine activate ER stress in hypothalamic neurons. These effects may induce decreased proopiomelanocortin (POMC) processing, increased neuropeptide Y (NPY) and agouti-related protein (AgRP) expression, autophagy, and leptin and insulin resistance, resulting in hyperphagia, decreased energy expenditure, and central inflammation, thereby causing weight gain. By activating ER stress, antipsychotics such as olanzapine activate hypothalamic astrocytes and Toll-like receptor 4 signaling, thereby causing inflammation and weight gain/obesity. Moreover, evidence suggests that antipsychotic-induced ER stress may be related to their antagonistic effects on neurotransmitter receptors such as DRD2 and the histamine H1 receptor. Taken together, ER stress inhibitors could be a potential effective intervention against SCZ and antipsychotic-induced weight gain and inflammation.