Bilirubin induces microglial NLRP3 inflammasome activation in vitro and in vivo

Potential inflammatory mechanisms of the ketogenic diet against febrile infection-related epilepsy syndrome

Febrile infection-related epilepsy syndrome (FIRES) is a rare epilepsy syndrome with unclear pathogenesis, characterized by fever-induced, super-refractory status epilepticus and high mortality. Studies have shown that ketogenic diet (KD) is effective in controlling convulsions in FIRES, but its mechanisms are unclear. This paper intends to summarize the mechanisms by which KD may exert effects against FIRES. Clinical studies have shown that patients with FIRES have elevated levels of various inflammatory factors such as interleukin (IL)-6, IL-8, IL-10, and so on. KD may exert anti-FIRES effects through several potential inflammatory pathways, including nuclear factor -κB (NF-κB) and NLR family pyrin domain containing 3 (NLRP3). Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) network suggested that KD may play an anti-inflammatory role through several pathways such as cellular senescence and neutrophil extracellular trap formation. These mechanisms need to be further investigated.

A new strategy for the treatment of intracerebral hemorrhage: Ferroptosis

Intracerebral hemorrhage, is a cerebrovascular disease with high morbidity, mortality, and disability. Due to the lack of effective clinical treatments, the development of new drugs to treat intracerebral hemorrhage is necessary. In recent years, ferroptosis has been found to play an important role in the pathophysiological process of intracerebral hemorrhage, which can be treated by inhibiting ferroptosis and thus intracerebral hemorrhage. This article aims to explain the mechanism of ferroptosis and its relationship to intracerebral hemorrhage. In the meantime, it briefly discusses the molecules identified to alleviate intracerebral hemorrhage by inhibiting ferroptosis, along with other clinical agents that are expected to treat intracerebral hemorrhage through this mechanism. In addition, a brief overview of the morphological alterations of different forms of cell death and their role in ICH is provided. Finally, the challenges that may arise in translating ferroptosis inhibitors from basic research to clinical use are presented. This article serves as a reference and provides insights to aid in the treatment of intracerebral hemorrhage in the clinic.

[Impact of chaperone-mediated autophagy on bilirubin-induced damage of mouse microglial cells]

OBJECTIVES

To investigate the effect of chaperone-mediated autophagy (CMA) on the damage of mouse microglial BV2 cells induce by unconjugated bilirubin (UCB).

METHODS

The BV2 cell experiments were divided into two parts. (1) For the CMA activation experiment: control group (treated with an equal volume of dimethyl sulfoxide), QX77 group (treated with 20 μmol/L QX77 for 24 hours), UCB group (treated with 40 μmol/L UCB for 24 hours), and UCB+QX77 group (treated with both 20 μmol/L QX77 and 40 μmol/L UCB for 24 hours). (2) For the cell transfection experiment: LAMP2A silencing control group (treated with an equal volume of dimethyl sulfoxide), LAMP2A silencing control+UCB group (treated with 40 μmol/L UCB for 24 hours), LAMP2A silencing group (treated with an equal volume of dimethyl sulfoxide), and LAMP2A silencing+UCB group (treated with 40 μmol/L UCB for 24 hours). The cell viability was assessed using the modified MTT method. The expression levels of p65, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), and cysteinyl aspartate specific proteinase-1 (caspase-1) were detected by Western blot. The relative mRNA expression levels of the inflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were determined by real-time quantitative polymerase chain reaction. Levels of IL-6 and TNF-α in the cell culture supernatant were measured using ELISA. The co-localization of heat shock cognate protein 70 with p65 and NLRP3 was detected by immunofluorescence.

RESULTS

Compared to the UCB group, the cell viability in the UCB+QX77 group increased, and the expression levels of inflammation-related proteins p65, NLRP3, and caspase-1, as well as the mRNA relative expression levels of IL-1β, IL-6, and TNF-α and levels of IL-6 and TNF-α decreased (P<0.05). Compared to the control group, there was co-localization of heat shock cognate protein 70 with p65 and NLRP3 in both the UCB and UCB+QX77 groups. After silencing the LAMP2A gene, compared to the LAMP2A silencing control+UCB group, the LAMP2A silencing+UCB group showed increased expression levels of inflammation-related proteins p65, NLRP3, and caspase-1, as well as increased mRNA relative expression levels of IL-1β, IL-6, and TNF-α and levels of IL-6 and TNF-α (P<0.05).

CONCLUSIONS

CMA is inhibited in UCB-induced BV2 cell damage, and activating CMA may reduce p65 and NLRP3 protein levels, suppress inflammatory responses, and counteract bilirubin neurotoxicity.

Glycyrrhizin alleviates varicellovirus bovinealpha 1-induced oxidative stress, inflammation, and apoptosis in MDBK cells by inhibiting NF-κB/NLRP3 axis through the Nrf2 signalling pathway

Varicellovirus bovinealpha 1 (BoAHV-1) is one of the crucial pathogens of bovine respiratory diseases, and its pathogenic mechanism involves oxidative stress, inflammation response, and apoptosis. Glycyrrhizin (GLY) possesses powerful antiviral, antioxidant, anti-inflammatory, and anti-apoptotic bioactivities. However, the anti-BoAHV-1 activity of GLY and its role in BoAHV-1-induced oxidative stress, inflammation, and apoptosis remain unclear. Therefore, the current study investigated the anti-BoAHV-1 effect of GLY and its ability to alleviate BoAHV-1-induced oxidative stress, inflammation, and apoptosis using an in vitro model (MDBK cells). Our results showed that BoAHV-1 titers significantly increased in MDBK cells after infection, and GLY reduced the BoAHV-1 titers in MDBK cells exposed to it. Furthermore, Interleukin (IL)-1β, IL-8, tumor necrosis factor (TNF)-α, phosphorylated NF-κB p65 (p-NF-κB p65), the NLR pyrin domain containing 3 (NLRP3), Caspase-1, and Cleaved Caspase-3 levels were significantly upregulated when MDBK cells were challenged with BoAHV-1. In BAY 11-7085 (a specific NF-κB inhibitor) treated MDBK cells, IL-1β, IL-8, TNF-α, p-NF-κB p65, NLRP3, Caspase-1, and Cleaved Caspase-3 levels were downregulated. Notably, GLY treatment had the same trend as the BAY 11-7085 treatment. Thus, these results suggested that GLY exerted anti-inflammatory and anti-apoptotic activities by blocking NF-κB/NLRP3 axis. In addition, after BoAHV-1 infection, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and p-NF-κB p65 and apoptosis rate were increased, and catalase (CAT) and glutathione peroxidase (GSH-Px) enzyme activities, as well as NF-E2-related nuclear factor erythroid-2 (Nrf2) protein expression were repressed. Compared with BoAHV-1-infected MDBK cells, GLY treatment significantly downregulated intracellular ROS, MDA, and p-NF-κB p65 levels and apoptotic rates and significantly increased intracellular CAT and GSH-Px enzyme activities and Nrf2 expression. Additionally, ML385 (a specific Nrf2 inhibitor) abolished the enhancing effect of GLY on Nrf2 and the attenuating effect on ROS, p-NF-κB p65, and apoptosis. These results suggested that GLY had an anti-BoAHV-1 effect and could mitigate BoAHV-1-induced oxidative stress, inflammation, and apoptosis by activating the Nrf2 signalling and restraining NF-κB/NLRP3 axis.

Bilirubin and Redox Stress in Age-Related Brain Diseases

Cellular redox status has a crucial role in brain physiology, as well as in pathologic conditions. Physiologic senescence, by dysregulating cellular redox homeostasis and decreasing antioxidant defenses, enhances the central nervous system's susceptibility to diseases. The reduction of free radical accumulation through lifestyle changes, and the supplementation of antioxidants as a prophylactic and therapeutic approach to increase brain health, are strongly suggested. Bilirubin is a powerful endogenous antioxidant, with more and more recognized roles as a biomarker of disease resistance, a predictor of all-cause mortality, and a molecule that may promote health in adults. The alteration of the expression and activity of the enzymes involved in bilirubin production, as well as an altered blood bilirubin level, are often reported in neurologic conditions and neurodegenerative diseases (together denoted NCDs) in aging. These changes may predict or contribute both positively and negatively to the diseases. Understanding the role of bilirubin in the onset and progression of NCDs will be functional to consider the benefits vs. the drawbacks and to hypothesize the best strategies for its manipulation for therapeutic purposes.