NLRP6 contributes to inflammation and brain injury following intracerebral haemorrhage by activating autophagy

Jingfang granules protects against intracerebral hemorrhage by inhibiting neuroinflammation and protecting blood-brain barrier damage

Intracerebral hemorrhage (ICH) can induce intensive oxidative stress, neuroinflammation, and brain cell apoptosis. However, conventional methods for ICH treatment have many disadvantages. There is an urgent need for alternative, effective therapies with minimal side effects. Pharmacodynamics experiment, molecular docking, network pharmacology, and metabolomics were adopted to investigate the treatment and its mechanism of Jingfang Granules (JFG) in ICH. In this study, we investigated the therapeutic effects of JFG on ICH using behavioral, brain water content and Magnetic resonance imaging experiments. However, the key active component and targets of JFG remain unknown. Here we verified that JFG was beneficial to improve brain injury after ICH. A network pharmacology analysis revealed that the anti-inflammatory effect of JFG is predominantly mediated by its activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway through Luteolin, (+)-Anomalin and Phaseol and their targeting of AKT1, tumor necrosis factorα (TNF-α), and interleukin-1β (IL-1β). Molecular docking analyses revealed an average affinity of -8.633 kcal/mol, indicating a binding strength of less than -5 kcal/mol. Metabolomic analysis showed that JFG exerted its therapeutic effect on ICH by regulating metabolic pathways, such as the metabolism of taurine and hypotaurine, biosynthesis of valine, leucine, and isoleucine. In conclusion, we demonstrated that JFG attenuated neuroinflammation and BBB injury subsequent to ICH by activating the PI3K/Akt signaling pathway.

BRCC3 mediates inflammation and pyroptosis in cerebral ischemia/reperfusion injury by activating the NLRP6 inflammasome

AIMS

Neuroinflammation and pyroptosis are key mediators of cerebral ischemia/reperfusion (I/R) injury-induced pathogenic cascades. BRCC3, the human homolog of BRCC36, is implicated in neurological disorders and plays a crucial role in neuroinflammation and pyroptosis. However, its effects and potential mechanisms in cerebral I/R injury in mice are unclear.

METHODS

Cellular localization of BRCC3 and the interaction between BRCC3 and NLRP6 were assessed. Middle cerebral artery occlusion/reperfusion (MCAO) and oxygen-glucose deprivation/reoxygenation (OGD/R) models were established in mice and HT22 cells, respectively, to simulate cerebral I/R injury in vivo and in vitro.

RESULTS

BRCC3 protein expression peaked 24 h after MCAO and OGD/R. BRCC3 knockdown reduced the inflammation and pyroptosis caused by cerebral I/R injury and ameliorated neurological deficits in mice after MCAO. The effects of BRCC3 on inflammation and pyroptosis may be mediated by NLRP6 inflammasome activation. Moreover, both BRCC3 and its N- and C-terminals interacted with NLRP6, and both BRCC3 and its terminals reduced NLRP6 ubiquitination. Additionally, BRCC3 affected the interaction between NLRP6 and ASC, which may be related to inflammasome activation.

CONCLUSION

BRCC3 shows promise as a novel target to enhance neurological recovery and attenuate the inflammatory responses and pyroptosis caused by NLRP6 activation in cerebral I/R injury.

Role of pyroptosis in the pathogenesis of various neurological diseases

Pyroptosis, an inflammatory programmed cell death process, has recently garnered significant attention due to its pivotal role in various neurological diseases. This review delves into the intricate molecular signaling pathways governing pyroptosis, encompassing both caspase-1 dependent and caspase-1 independent routes, while emphasizing the critical role played by the inflammasome machinery in initiating cell death. Notably, we explore the Nucleotide-binding domain leucine-rich repeat (NLR) containing protein family, the Absent in melanoma 2-like receptor family, and the Pyrin receptor family as essential activators of pyroptosis. Additionally, we comprehensively examine the Gasdermin family, renowned for their role as executioner proteins in pyroptosis. Central to our review is the interplay between pyroptosis and various central nervous system (CNS) cell types, including astrocytes, microglia, neurons, and the blood-brain barrier (BBB). Pyroptosis emerges as a significant factor in the pathophysiology of each cell type, highlighting its far-reaching impact on neurological diseases. This review also thoroughly addresses the involvement of pyroptosis in specific neurological conditions, such as HIV infection, drug abuse-mediated pathologies, Alzheimer's disease, and Parkinson's disease. These discussions illuminate the intricate connections between pyroptosis, chronic inflammation, and cell death in the development of these disorders. We also conducted a comparative analysis, contrasting pyroptosis with other cell death mechanisms, thereby shedding light on their unique aspects. This approach helps clarify the distinct contributions of pyroptosis to neuroinflammatory processes. In conclusion, this review offers a comprehensive exploration of the role of pyroptosis in various neurological diseases, emphasizing its multifaceted molecular mechanisms within various CNS cell types. By elucidating the link between pyroptosis and chronic inflammation in the context of neurodegenerative disorders and infections, it provides valuable insights into potential therapeutic targets for mitigating these conditions.

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.

Mechanisms and therapeutic targets of mitophagy after intracerebral hemorrhage

Mitochondria are dynamic organelles responsible for cellular energy production. In addition to regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, clearance of damaged organelles, signaling, and cell survival in the context of injury and pathology. In stroke, the mechanisms underlying brain injury secondary to intracerebral hemorrhage are complex and involve cellular hypoxia, oxidative stress, inflammatory responses, and apoptosis. Recent studies have shown that mitochondrial damage and autophagy are essential for neuronal metabolism and functional recovery after intracerebral hemorrhage, and are closely related to inflammatory responses, oxidative stress, apoptosis, and other pathological processes. Because hypoxia and inflammatory responses can cause secondary damage after intracerebral hemorrhage, the restoration of mitochondrial function and timely clearance of damaged mitochondria have neuroprotective effects. Based on studies on mitochondrial autophagy (mitophagy), cellular inflammation, apoptosis, ferroptosis, the BNIP3 autophagy gene, pharmacological and other regulatory approaches, and normobaric oxygen (NBO) therapy, this article further explores the neuroprotective role of mitophagy after intracerebral hemorrhage.

N6-methyladenosine demethylase FTO regulates synaptic and cognitive impairment by destabilizing PTEN mRNA in hypoxic-ischemic neonatal rats

Hypoxic-ischemic brain damage (HIBD) can result in significant global rates of neonatal death or permanent neurological disability. N6-methyladenosine (m6A) modification of RNA influences fundamental aspects of RNA metabolism, and m6A dysregulation is implicated in various neurological diseases. However, the biological roles and clinical significance of m6A in HIBD remain unclear. We currently evaluated the effect of HIBD on cerebral m6A methylation in RNAs in neonatal rats. The m6A dot blot assay showed a global augmentation in RNA m6A methylation post-HI. Herein, we also report on demethylase FTO, which is markedly downregulated in the hippocampus and is the main factor involved with aberrant m6A modification following HI. By conducting a comprehensive analysis of RNA-seq data and m6A microarray results, we found that transcripts with m6A modifications were more highly expressed overall than transcripts without m6A modifications. The overexpression of FTO resulted in the promotion of Akt/mTOR pathway hyperactivation, while simultaneously inhibiting autophagic function. This is carried out by the demethylation activity of FTO, which selectively demethylates transcripts of phosphatase and tensin homolog (PTEN), thus promoting its degradation and reduced protein expression after HI. Moreover, the synaptic and neurocognitive disorders induced by HI were effectively reversed through the overexpression of FTO in the hippocampus. Cumulatively, these findings demonstrate the functional importance of FTO-dependent hippocampal m6A methylome in cognitive function and provides novel mechanistic insights into the therapeutic potentials of FTO in neonatal HIBD.

Spotlight on NLRP6 and Tumor Research Situation: A Potential Cancer Participant

NOD-like receptor family pyrin domain containing 6 (NLRP6) is a new pattern recognition receptor in the mammalian innate immune system. Both the liver and the gut exhibit substantial levels of cytoplasmic expression. It can speed up cell response to endogenous danger signals or exogenous pathogen infection. NLRP6 can function in various ways as an inflammasome or a noninflammasome. The understanding of NLRP6 is steadily increasing thanks to ongoing investigations, but due to discrepancies in how those studies have described their link with tumors, the significance of NLRP6 in the emergence of cancer is still debatable as of this writing. This article will use the structure and function of NLRP6 as the pivotal point and thoroughly explain the present interactions between NLRP6 and tumors and any possible clinical benefits.

NPAS4 Exacerbates Pyroptosis via Transcriptionally Regulating NLRP6 in the Acute Phase of Intracerebral Hemorrhage in Mice

Intracerebral hemorrhage (ICH) is a severe cerebrovascular disease with a high disability rate and high mortality, and pyroptosis is a type of programmed cell death in the acute phase of ICH. Neuronal Per-Arnt-Sim domain protein 4 (Npas4) is a specific transcription factor highly expressed in the nervous system, yet the role of NPAS4 in ICH-induced pyroptosis is not fully understood. NLR family Pyrin-domain-containing 6 (NLRP6), a new member of the Nod-like receptor family, aggravates pyroptosis via activating cysteine protease-1 (Caspase-1) and Caspase-11. In this study, we found that NPAS4 was upregulated in human and mouse peri-hematoma brain tissues and peaked at approximately 24 h after ICH modeling. Additionally, NPAS4 knockdown improved neurologic dysfunction and brain damage induced by ICH in mice after 24 h. Meanwhile, inhibiting NPAS4 expression reduced the levels of myeloperoxidase (MPO)-positive cells and Caspase-1/TUNEL-double-positive cells and decreased cleaved Caspase-1, cleaved Caspase-11, and N-terminal GSDMD levels. Consistently, NPAS4 overexpression reversed the above alternations after ICH in the mice. Moreover, NPAS4 could interact with the Nlrp6 promoter region (-400--391 bp and -33--24 bp) and activate the transcription of Nlrp6. Altogether, our study demonstrated that NPAS4, as a transcription factor, can exacerbate pyroptosis and transcriptionally activate NLRP6 in the acute phase of intracerebral hemorrhage in mice.

Disruption of the Intestinal Mucosal Barrier Induced by High Fructose and Restraint Stress Is Regulated by the Intestinal Microbiota and Microbiota Metabolites

Environmental (restraint stress) and dietary (high fructose) factors are key triggers for flares of inflammatory bowel disease; however, the mechanisms involved in this phenomenon are not fully elucidated. This study aimed to investigate the mechanisms by which restraint stress and high fructose damage the intestinal mucosal immune barrier. The feces of C57BL/6J mice were subjected to 16S rRNA and untargeted metabolome sequencing, and the intestinal histological structure was analyzed by immunohistochemistry and immunofluorescence staining. The mRNA and protein levels of the intestinal protein were analyzed by reverse transcription-PCR (RT-PCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). The metabolites of the microbiota were tested in vitro, and Akkermansia muciniphila was used for colonization in vivo. Dietary fructose exacerbated the development of restraint stress, with an extensive change in the composition of the gut microbiota and microbial metabolites. The disturbance of the microbiota composition led to an increase in the abundance of histamine and a decrease in the abundance of taurine, which inhibited the expression of tight junction and MUC2 proteins, destroyed the function of NLRP6, and reduced intestinal autophagy level; this in turn disrupted the function of colonic goblet cells to secrete mucus, leading to defects in the intestinal mucosal barrier, which ultimately codrives colon autoinflammation. However, A. muciniphila supplementation counteracted damage to the intestinal mucosal barrier by high fructose and restraint stress. Therefore, the gut microbiota and microbiota metabolites play an important role in maintaining microenvironment homeostasis of the intestinal mucosal barrier. IMPORTANCE A high-fructose diet aggravated restraint stress-induced changes in the composition of the intestinal microbiome, in which the abundance of A. muciniphila was significantly increased. The high-fructose diet exacerbated restraint stress-induced the changes in the composition of the microbial metabolites, with taurine abundance being downregulated and histamine abundance upregulated. High fructose and restraint stress induced colonic mucosal immune barrier damage, possibly due to changes in the abundance of the microbial metabolites taurine and histamine. Colonization with A. muciniphila stimulated the expression of the NLRP6 inflammasome and activated autophagy in goblet cells, thereby producing more new mucins, which could protect the intestinal mucosal barrier.

Autophagy regulates inflammation in intracerebral hemorrhage: Enemy or friend?

Intracerebral hemorrhage (ICH) is the second-largest stroke subtype and has a high mortality and disability rate. Secondary brain injury (SBI) is delayed after ICH. The main contributors to SBI are inflammation, oxidative stress, and excitotoxicity. Harmful substances from blood and hemolysis, such as hemoglobin, thrombin, and iron, induce SBI. When cells suffer stress, a critical protective mechanism called "autophagy" help to maintain the homeostasis of damaged cells, remove harmful substances or damaged organelles, and recycle them. Autophagy plays a critical role in the pathology of ICH, and its function remains controversial. Several lines of evidence demonstrate a pro-survival role for autophagy in ICH by facilitating the removal of damaged proteins and organelles. However, many studies have found that heme and iron can aggravate SBI by enhancing autophagy. Autophagy and inflammation are essential culprits in the progression of brain injury. It is a fascinating hypothesis that autophagy regulates inflammation in ICH-induced SBI. Autophagy could degrade and clear pro-IL-1β and apoptosis-associated speck-like protein containing a CARD (ASC) to antagonize NLRP3-mediated inflammation. In addition, mitophagy can remove endogenous activators of inflammasomes, such as reactive oxygen species (ROS), inflammatory components, and cytokines, in damaged mitochondria. However, many studies support the idea that autophagy activates microglia and aggravates microglial inflammation via the toll-like receptor 4 (TLR4) pathway. In addition, autophagy can promote ICH-induced SBI through inflammasome-dependent NLRP6-mediated inflammation. Moreover, some resident cells in the brain are involved in autophagy in regulating inflammation after ICH. Some compounds or therapeutic targets that regulate inflammation by autophagy may represent promising candidates for the treatment of ICH-induced SBI. In conclusion, the mutual regulation of autophagy and inflammation in ICH is worth exploring. The control of inflammation by autophagy will hopefully prove to be an essential treatment target for ICH.

MicroRNAs modulate neuroinflammation after intracerebral hemorrhage: Prospects for new therapy

Intracerebral hemorrhage (ICH) is the most common subtype of hemorrhagic stroke. After ICH, blood components extravasate from vessels into the brain, activating immune cells and causing them to release a series of inflammatory mediators. Immune cells, together with inflammatory mediators, lead to neuroinflammation in the perihematomal region and the whole brain, and neuroinflammation is closely related to secondary brain injury as well as functional recovery of the brain. Despite recent progress in understanding the pathophysiology of ICH, there is still no effective treatment for this disease. MicroRNAs (miRNAs) are non-coding RNAs 17-25 nucleotides in length that are generated naturally in the human body. They bind complementarily to messenger RNAs and suppress translation, thus regulating gene expression at the post-transcriptional level. They have been found to regulate the pathophysiological process of ICH, particularly the neuroinflammatory cascade. Multiple preclinical studies have shown that manipulating the expression and activity of miRNAs can modulate immune cell activities, influence neuroinflammatory responses, and ultimately affect neurological functions after ICH. This implicates the potentially crucial roles of miRNAs in post-ICH neuroinflammation and indicates the possibility of applying miRNA-based therapeutics for this disease. Thus, this review aims to address the pathophysiological roles and molecular underpinnings of miRNAs in the regulation of neuroinflammation after ICH. With a more sophisticated understanding of ICH and miRNAs, it is possible to translate these findings into new pharmacological therapies for ICH.

Neuroinflammation of microglia polarization in intracerebral hemorrhage and its potential targets for intervention

Microglia are the resident immune cells of the central nervous system (CNS) and play a key role in neurological diseases, including intracerebral hemorrhage (ICH). Microglia are activated to acquire either pro-inflammatory or anti-inflammatory phenotypes. After the onset of ICH, pro-inflammatory mediators produced by microglia at the early stages serve as a crucial character in neuroinflammation. Conversely, switching the microglial shift to an anti-inflammatory phenotype could alleviate inflammatory response and incite recovery. This review will elucidate the dynamic profiles of microglia phenotypes and their available shift following ICH. This study can facilitate an understanding of the self-regulatory functions of the immune system involving the shift of microglia phenotypes in ICH. Moreover, suggestions for future preclinical and clinical research and potential intervention strategies are discussed.

The potential mechanism of BPF-induced neurotoxicity in adult zebrafish: Correlation between untargeted metabolomics and gut microbiota

Bisphenol F (BPF) is becoming the main substitute for bisphenol A (BPA) in plastics for food and beverage applications. Previous studies have demonstrated the neurotoxicity of BPF; however, its lifecycle toxicity and the underlying mechanisms remain poorly understood. In the current study, zebrafish were continuously exposed to BPF for four months from the embryo to adult stages in order to assess its neurotoxicity. Locomotor behaviors significantly decreased after BPF exposure, which was accompanied by a decrease in body weight, length, and hatching rate. Additionally, BPF increased the expression of inflammatory genes in the brain and destroyed the zebrafishes' intestinal integrity. Meanwhile, the 16S rRNA gene sequence results showed a significantly decreased microbiota abundance and diversity following BPF treatment. Neurotransmitter metabolites were also altered by BPF. Notably, the correlation analysis between microbiota and neurotransmitter metabolism verified that gut microbiota dysbiosis was closely related to the disturbance of neurotransmitter metabolites. Therefore, the present study evaluated the neurotoxicity of lifecycle exposure to BPF and unraveled a novel mechanism involving disturbance of neurotransmitter metabolism and gut dysbiosis, which may provide potential targets for BPF-mediated neurotoxicity.

Microglial pyroptosis: Therapeutic target in secondary brain injury following intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a major cerebrovascular illness that causes substantial neurological sequelae and dysfunction caused by secondary brain injury (SBI), and there are no effective therapies to mitigate the disability. Microglia, the brain-resident macrophage, participates in the primary inflammatory response, and activation of microglia to an M1-like phenotype largely takes place in the acute phase following ICH. A growing body of research suggests that the pathophysiology of SBI after ICH is mediated by an inflammatory response mediated by microglial-pyroptotic inflammasomes, while inhibiting the activation of microglial pyroptosis could suppress the inflammatory cascade reaction, thus attenuating the brain injury after ICH. Pyroptosis is characterized by rapid plasma membrane disruption, followed by the release of cellular contents and pro-inflammatory mediators. In this review, we outline the molecular mechanism of microglial pyroptosis and summarize the up-to-date evidence of its involvement in the pathological process of ICH, and highlight microglial pyroptosis-targeted strategies that have the potential to cure intracerebral hemorrhage. This review contributes to a better understanding of the function of microglial pyroptosis in ICH and assesses it as a possible therapeutic target.

The association between Monocyte-to-Lymphocyte ratio and postoperative delirium in ICU patients in cardiac surgery

Objective

To analyze the relationship between monocyte‐to‐lymphocyte ratio (MLR) and postoperative delirium (POD).

Methods

This cohort study was conducted in the Medical Information Mart for Intensive Care‐III (MIMIC‐III) version 1.4 database. MLR was measured according to the complete blood count. ICD‐9 was used to measure postoperative delirium. Multivariable logistic regression was utilized to examine the relationship between MLR and POD.

Results

Three thousand eight hundred sixty‐eight patients who had received cardiac surgery were retrospectively enrolled, including 2171 males and 1697 females, with a mean age of 63.9 ± 16.2 years. The univariate analysis suggested that high MLR (as a continuous variable) as associated with a 21% higher risk of POD (O R: 1.12, 95% CI, 1.02, 1.43, p = 0.0259), After adjustments for other confounding factors, gender, age, race, temperature, SBP, DBP, MAP, respiratory rate, SOFA, peripheral vascular disease, AG, psychoses, drug, and alcohol addiction, the results showed that high MLR (as a continuous variable) independently served as a risk factor for POD (OR: 1.21; 95% CI: 1.01–1.44; p = 0.0378). MLR was assessed as quintile and tertiles, high MLR was an independent risk factor for POD. In the subgroup analysis, there were no differences in MLR for patients with POD in pre‐specified subgroups.

Conclusions

Monocyte‐to‐lymphocyte ratio was a risk factor for POD. More research is necessary to thoroughly examine the function of MLR in POD.

GM130 protects against blood-brain barrier disruption and brain injury after intracerebral hemorrhage by regulating autophagy formation

Blood-brain barrier (BBB) disruption following intracerebral hemorrhage (ICH) significantly contributes to neurological deficits. Tight junction (TJ) protein loss in brain endothelial cells leads to BBB disruption. We previously revealed the importance of the Golgi apparatus (GA) in maintaining TJ integrity in mouse brain endothelial (bEnd.3) cells, but the specific mechanisms remain unknown. Herein, we investigated the potential role of the GA in BBB damage and neurological dysfunction after ICH using bEnd.3 cells and hemin to mimic hemorrhage in vitro. We used a rat hemorrhage stroke model to evaluate the role of the GA in BBB disruption during ICH. GM130 levels decreased with ICH length in vivo and in vitro. TJ protein destruction further increased following GM130 silencing. GM130 overexpression alleviated TJ protein impairment and improved BBB integrity. bEnd.3 cells treated with an autophagy inhibitor showed reduced TJ protein damage following GM130 silencing. The intracerebroventricular injection of an autophagy inhibitor rescued GM130 silencing-induced BBB leakage. Thus, TJ proteins were destroyed by excessive autophagic pathway activation following ICH, whereas GM130 protected against TJ damage by maintaining proper autophagy. We suggest that GM130-regulated selective autophagy modulates BBB integrity and GM130 upregulation suppresses the autophagy-lysosome pathway, which might maintain BBB function. Therefore, GA protection is beneficial for ICH, and GM130 is a potential therapeutic target for its treatment.

Effects and mechanisms of CTRP3 overexpression in secondary brain injury following intracerebral hemorrhage in rats

C1q/TNF-related protein-3 (CTRP3) is a novel adipokine that serves an important role in oxidative stress, anti-apoptosis, anti-inflammation and immune regulation. The aim of the present study was to investigate the protective role of CTRP3 against intracerebral hemorrhage (ICH)-induced brain injury. A model of autologous arterial blood-induced ICH was constructed in rats. Intracerebral infusion of a lentivirus carrying the CTRP3 gene was used to induce CTRP3 overexpression in the brain. The effects and mechanisms of CTRP3 overexpression on brain injury were investigated by detecting brain edema, blood-brain barrier (BBB) integrity, neurological function and inflammatory-associated factors 3 days after ICH. The present results demonstrated that CTRP3 overexpression ameliorated ICH-induced neurological dysfunction, decreased brain edema, maintained BBB integrity and attenuated inflammation. The protective effect of CTRP3 overexpression was associated with increased activation of silent information regulator 1 (SIRT1). In conclusion, the present study demonstrated that CTRP3 overexpression protected against ICH-induced brain injury in rats, potentially via activating the SIRT1 signaling pathway.

Pyridoxal Isonicotinoyl Hydrazone Improves Neurological Recovery by Attenuating Ferroptosis and Inflammation in Cerebral Hemorrhagic Mice

Ferroptosis and inflammation induced by cerebral hemorrhage result in an excessive inflammatory response and irreversible neuronal injury. Alleviating ferroptosis might be an effective way to prevent neuroinflammatory injury and promote neural functional recovery. Pyridoxal isonicotinoyl hydrazine (PIH), a lipophilic iron-chelating agent, has been reported to reduce excess iron-induced cytotoxicity. However, whether PIH could ameliorate the effects of hemorrhagic stroke is not completely understood. In the present study, the preventive effects of PIH in an intracerebral hemorrhage (ICH) mouse model were investigated. Neurological score, rotarod test, and immunofluorescence around the hematoma were assessed to evaluate the effects of PIH on hemorrhagic injury. The involvement of ferroptosis and inflammation was also examined in vitro to explore the underlying mechanism. Results showed that administration of PIH prevented neuronal cell death and reduced lipid peroxidation in Erastin-treated PC-12 cells. In vivo, mice treated with PIH after ICH attenuated neurological deficit scores. Additionally, we found PIH reduced ROS production, iron accumulation, and lipid peroxidation around the hematoma peripheral tissue. Meanwhile, ICH mice treated with PIH showed an upregulation of the key ferroptosis enzyme, glutathione peroxidase 4, and downregulation of cyclooxygenase-2. Moreover, PIH administration inhibited proinflammatory polarization and reduced interleukin-1 beta and tumor necrosis factor alpha in ICH mice. Collectively, these results demonstrated that PIH protects mice against hemorrhage stroke, which was associated with mitigation of inflammation and ferroptosis.

Roles of PRR-Mediated Signaling Pathways in the Regulation of Oxidative Stress and Inflammatory Diseases

Oxidative stress is a major contributor to the pathogenesis of various inflammatory diseases. Accumulating evidence has shown that oxidative stress is characterized by the overproduction of reactive oxygen species (ROS). Previous reviews have highlighted inflammatory signaling pathways, biomarkers, molecular targets, and pathogenetic functions mediated by oxidative stress in various diseases. The inflammatory signaling cascades are initiated through the recognition of host cell-derived damage associated molecular patterns (DAMPs) and microorganism-derived pathogen associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). In this review, the effects of PRRs from the Toll-like (TLRs), the retinoic acid-induced gene I (RIG-I)-like receptors (RLRs) and the NOD-like (NLRs) families, and the activation of these signaling pathways in regulating the production of ROS and/or oxidative stress are summarized. Furthermore, important directions for future studies, especially for pathogen-induced signaling pathways through oxidative stress are also reviewed. The present review will highlight potential therapeutic strategies relevant to inflammatory diseases based on the correlations between ROS regulation and PRRs-mediated signaling pathways.

FUNDC1 inhibits NLRP3-mediated inflammation after intracerebral hemorrhage by promoting mitophagy in mice

Inflammation is a fundamental element in secondary brain injury (SBI) besides intracerebral hemorrhage (ICH). Pyrin domain that contains 3 inflammasome (NLRP3) was regarded as a key role of the nod-like receptor family and played an important part in the inflammatory response following ICH-induced injury. FUN14 domain containing 1 (FUNDC1) is a kind of mitophagy receptor, which can eliminate mitochondrial dysfunction after hypoxia and mitochondrial stress. Previous research showed that mitophagy prevents inflammation through inhibiting NLRP3 inflammasome pathway. However, the relationship between FUNDC1 and ICH-induced inflammatory response stays uncertain. In this study, we investigate that FUNDC1 inhibit NLRP3 inflammasome activation by promoting mitophagy, thereby alleviate ICH-induced injury. We established ICH model by injecting tail venous blood into the basal ganglia of C57 mice (healthy, male adult). We injected siRNA to knockdown FUNDC1. In order to deeply seek for the mechanisms of FUNDC1 in ICH-induced injury, FUNDC1 was overexpressed by adeno-associated virus (AAV) and mitophagy was suppressed by specific inhibitor (mdivi-1). The protein level of FUNDC1 was upregulated and got peak at 12h after ICH. We noticed that silencing FUNDC1 can suppress mitophagy, promote NLRP3-mediated inflammation and exacerbate ICH injury. Furthermore, the results indicated that mitophagy participated in the inhibitory effect of FUNDC1 on NLRP3-mediated inflammatory response after ICH. Our results showed that FUNDC1 alleviated ICH-induced inflammation in mice by promoting mitophagy. Those data suggested that FUNDC1 may be a potential target for the treatment of ICH.

Microglia: A Double-Edged Sword in Intracerebral Hemorrhage From Basic Mechanisms to Clinical Research

Microglia are the resident immune cells of the central nervous system (CNS). It is well established that microglia are activated and polarized to acquire different inflammatory phenotypes, either pro-inflammatory or anti-inflammatory phenotypes, which act as a critical component in the neuroinflammation following intracerebral hemorrhage (ICH). Microglia produce pro-inflammatory mediators at the early stages after ICH onset, anti-inflammatory microglia with neuroprotective effects appear to be suppressed. Previous research found that driving microglia towards an anti-inflammatory phenotype could restrict inflammation and engulf cellular debris. The principal objective of this review is to analyze the phenotypes and dynamic profiles of microglia as well as their shift in functional response following ICH. The results may further the understanding of the body's self-regulatory functions involving microglia following ICH. On this basis, suggestions for future clinical development and research are provided.

NLRP6 in host defense and intestinal inflammation

NLRP6 is a member of the NLR (nucleotide-oligomerization domain-like receptor) family of proteins that recognize pathogen-derived factors and damage-associated molecular patterns in the cytosol. The function of NLRP6 has been attributed to the maintenance of epithelial integrity and host defense against microbial infections. Under some physiological conditions, NLRP6 forms a complex with ASC and caspase-1 or caspase-11 to form an inflammasome complex cleaving pro-interleukin-1β (IL-1β) and IL-18 into their biologically active forms. Here, we summarize recent advances in the understanding of the mechanisms of activation of the NLRP6 inflammasome and discuss its relevance to human disease.