The balance between AIM2-associated inflammation and autophagy: the role of CHMP2A in brain injury after cardiac arrest

Invasive metastatic tumor-camouflaged ROS responsive nanosystem for targeting therapeutic brain injury after cardiac arrest

Drug transmission through the blood-brain barrier (BBB) is considered an arduous challenge for brain injury treatment following the return of spontaneous circulation after cardiac arrest (CA-ROSC). Inspired by the propensity of melanoma metastasis to the brain, B16F10 cell membranes are camouflaged on 2-methoxyestradiol (2ME2)-loaded reactive oxygen species (ROS)-triggered "Padlock" nanoparticles that are constructed by phenylboronic acid pinacol esters conjugated D-a-tocopheryl polyethylene glycol succinate (TPGS-PBAP). The biomimetic nanoparticles (BM@TP/2ME2) can be internalized, mainly mediated by the mutual recognition and interaction between CD44v6 expressed on B16F10 cell membranes and hyaluronic acid on cerebral vascular endothelial cells, and they responsively release 2ME2 by the oxidative stress microenvironment. Notably, BM@TP/2ME2 can scavenge excessive ROS to reestablish redox balance, reverse neuroinflammation, and restore autophagic flux in damaged neurons, eventually exerting a remarkable neuroprotective effect after CA-ROSC in vitro and in vivo. This biomimetic drug delivery system is a novel and promising strategy for the treatment of cerebral ischemia-reperfusion injury after CA-ROSC.

The cytoplasmic sensor, the AIM2 inflammasome: A precise therapeutic target in vascular and metabolic diseases

Cardio-cerebrovascular diseases encompass pathological changes in the heart, brain and vascular system, which pose a great threat to health and well-being worldwide. Moreover, metabolic diseases contribute to and exacerbate the impact of vascular diseases. Inflammation is a complex process that protects against noxious stimuli but is also dysregulated in numerous so-called inflammatory diseases, one of which is atherosclerosis. Inflammation involves multiple organ systems and a complex cascade of molecular and cellular events. Numerous studies have shown that inflammation plays a vital role in cardio-cerebrovascular diseases and metabolic diseases. The absent in melanoma 2 (AIM2) inflammasome detects and is subsequently activated by double-stranded DNA in damaged cells and pathogens. With the assistance of the mature effector molecule caspase-1, the AIM2 inflammasome performs crucial biological functions that underpin its involvement in cardio-cerebrovascular diseases and related metabolic diseases: The production of interleukin-1 beta (IL-1β), interleukin-18 (IL-18) and N-terminal pore-forming Gasdermin D fragment (GSDMD-N) mediates a series of inflammatory responses and programmed cell death (pyroptosis and PANoptosis). Currently, several agents have been reported to inhibit the activity of the AIM2 inflammasome and have the potential to be evaluated for use in clinical settings. In this review, we systemically elucidate the assembly, biological functions, regulation and mechanisms of the AIM2 inflammasome in cardio-cerebrovascular diseases and related metabolic diseases and outline the inhibitory agents of the AIM2 inflammasome as potential therapeutic drugs.

MLKL Protects Pulmonary Endothelial Cells in Acute Lung Injury

The role of autophagy in pulmonary microvascular endothelial cells (PMVECs) is controversial in LPS-induced acute lung injury (ALI). Mixed lineage kinase domain-like pseudokinase (MLKL) has recently been reported to maintain cell survival by facilitating autophagic flux in response to starvation rather than its well-recognized role in necroptosis. Using a mouse PMVEC and LPS-induced ALI model, we showed that in PMVECs, MLKL was phosphorylated (p-MLKL) and autophagic flux was accelerated at the early stage of LPS stimulation (1-3 h), manifested by increases in concentrations of lipidated MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β; LC3-II), decreases in concentrations of SQSTM1/p62 (sequestosome 1), and fusion of the autophagosome and lysosome by pHluorin-mKate2-human LC3 assay, which were all reversed by either MLKL inhibitor or siRNA MLKL. In mice, the inhibition of MLKL increased vascular permeability and aggravated mouse ALI upon 3-hour LPS stimulation. The p-MLKL induced by short-term LPS formed multimers to facilitate the closure of the phagophore by HaloTag-LC3 autophagosome completion assay. The charged multivesicular body protein 2A (CHMP2A) is essential in the process of phagophore closure into the nascent autophagosome. In agreement with the p-MLKL change, CHMP2A concentrations markedly increased during 1-3-hour LPS stimulation. CHMP2A knockdown blocked autophagic flux upon LPS stimulation, whereas CHMP2A overexpression boosted autophagic flux and attenuated mouse ALI even in the presence of MLKL inhibitor. We propose that the activated MLKL induced by short-term LPS facilitates autophagic flux by accelerating the closure of the phagophore via CHMP2A, thus protecting PMVECs and alleviating LPS-induced ALI.

"Other Than NLRP3" Inflammasomes: Multiple Roles in Brain Disease

Human neuroinflammatory and neurodegenerative diseases, whose prevalence keeps rising, are still unsolved pathobiological/therapeutical problems. Among others, recent etiology hypotheses stressed as their main driver a chronic neuroinflammation, which is mediated by innate immunity-related protein oligomers: the inflammasomes. A panoply of exogenous and/or endogenous harmful agents activates inflammasomes' assembly, signaling, and IL-1β/IL-18 production and neural cells' pyroptotic death. The underlying concept is that inflammasomes' chronic activation advances neurodegeneration while their short-lasting operation restores tissue homeostasis. Hence, from a therapeutic standpoint, it is crucial to understand inflammasomes' regulatory mechanisms. About this, a deluge of recent studies focused on the NLRP3 inflammasome with suggestions that its pharmacologic block would hinder neurodegeneration. Yet hitherto no evidence proves this view. Moreover, known inflammasomes are numerous, and the mechanisms regulating their expression and function may vary with the involved animal species and strains, as well as organs and cells, and the harmful factors triggered as a result. Therefore, while presently leaving out some little-studied inflammasomes, this review focuses on the "other than NLRP3" inflammasomes that participate in neuroinflammation's complex mechanisms: NLRP1, NLRP2, NLRC4, and AIM2. Although human-specific data about them are relatively scant, we stress that only a holistic view including several human brain inflammasomes and other potential pathogenetic drivers will lead to successful therapies for neuroinflammatory and neurodegenerative diseases.

Anti-influenza drug screening and inhibition of apigetrin on influenza A virus replication via TLR4 and autophagy pathways

Activation of Toll-like receptor (TLR) 4 plays important roles in the influenzaA virus (IAV) infection. To explore TLR4 inhibitors, 161 traditional Chinese medicines (TCMs) were screened. Further, we screened out Ixeris sonchifolia Hance, and its active compound, Apigetrin (apigenin-7-O-glucoside). Antiviral activity of Apigetrin was determined by plaque assay. We also further investigated the influence of Apigetrin on immune signaling pathways including TLRs, MAPK, NF-κB and autophagy pathways. The in-vitro results showed that the extract and its several ingredients could significantly inhibit IAV replication. Apigetrin significantly improved IAV-induced oxidative stress, inhibited the IAV-induced cytokine storm by suppressing the excessive activation of TLR3/4/7, JNK/p38 MAPK and NF-κB. Apigetrin decreased autophagosome accumulation and promoted degradation of IAV protein. Interestingly, Apigetrin antiviral activity was reversed by using H2O2 and the agonists of TLR4, JNK/p38, NF-κB and autophagy. Most important, the in-vitro effective concentration is higher than the reported plasma concentration. The in-vivo test showed that Apigetrin significantly increased the average survival time, reduced the lung edema and IAV replication. In conclusion, we have found that Ixeris sonchifolia Hance and its several ingredients can inhibit IAV infection, and the mechanisms of action of Apigetrin against IAV is by regulating TLR4 and autophagy signaling pathways.

GABAB Receptor Activation Attenuates Neuronal Pyroptosis in Post-cardiac Arrest Brain Injury

Brain injury is a major cause of death and disability after cardiac arrest (CA). Previous studies have shown that activating GABAB receptors significantly improves neurological function after CA, but the mechanism of this neuronal protection of damaged neurons remains unclear. Thus, the present study aimed to investigate whether GABAB receptor activation protects against neuronal injury and to reveal the underlying protective mechanisms. In this study, rats underwent 10 min of asphyxia to induce CA, and SH-SY5Y cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) to establish in vivo and in vitro models of hypoxic neuronal injury. Differential gene expression between CA rats and sham-operated rats was identified using RNA-seq. TUNEL and Nissl staining were used to evaluate cortical neuron damage, while Western blotting, qRT-PCR, and immunofluorescence assays were conducted to measure pyroptosis-related indicators. Furthermore, cellular models with high expression of caspase-11 were established to reveal the novel molecular mechanisms by which GABAB receptor activation exerts neuroprotective effects. Intriguingly, our results showed that caspase-11 and GSDMD were highly expressed in rats experiencing cardiac arrest. Specifically, GSDMD was expressed in neurons in the M1 area of the cerebral cortex. Moreover, activation of the GABAB receptor exerted a protective effect on neurons both in vivo and in vitro. Baclofen attenuated caspase-11 activation and neuronal pyroptosis after CA, and the anti-neuronal pyroptosis effect of baclofen was abolished by overexpression of caspase-11 in neuronal cells. In conclusion, GABAB receptor activation may play a neuroprotective role by alleviating neuronal pyroptosis through a mechanism involving caspase-11.

Baicalein Suppresses NLRP3 and AIM2 Inflammasome-Mediated Pyroptosis in Macrophages Infected by Mycobacterium tuberculosis via Induced Autophagy

Mycobacterium tuberculosis (Mtb) continues to pose a significant threat to global health because it causes granulomas and systemic inflammatory responses during active tuberculosis (TB). Mtb can induce macrophage pyroptosis, which results in the release of IL-1β and causes tissue damage, thereby promoting its spread. In the absence of anti-TB drugs, host-directed therapy (HDT) has been demonstrated to be an effective strategy against TB. In this study, we used an in vitro Mtb-infected macrophage model to assess the effect of baicalein, derived from Scutellariae radix, on pyroptosis induced in Mtb-infected macrophages. Further, we investigated the molecular mechanisms underlying the actions of baicalein. The results of the study suggest that baicalein inhibits pyroptosis in Mtb-infected macrophages by downregulating the assembly of AIM2 and NLRP3 inflammasome and promoting autophagy. Further research has also shown that the mechanism by which baicalein promotes autophagy may involve the inhibition of the activation of the Akt/mTOR pathway and the inhibition of the AIM2 protein, which affects the levels of CHMP2A protein required to promote autophagy. Thus, our data show that baicalein can inhibit Mtb infection-induced macrophage pyroptosis and has the potential to be a new adjunctive HDT drug. IMPORTANCE Current strategies for treating drug-resistant tuberculosis have limited efficacy and undesirable side effects; hence, research on new treatments, including innovative medications, is required. Host-directed therapy (HDT) has emerged as a viable strategy for modulating host cell responses in order to enhance protective immunity against infections. Baicalein, extracted from Scutellariae radix, was shown to inhibit pyroptosis caused by Mycobacterium tuberculosis-infected macrophages and was associated with autophagy. Our findings reveal that baicalein can be used as an adjunctive treatment for tuberculosis or other inflammatory diseases by regulating immune function and enhancing the antibacterial ability of the host. It also provides a new idea for exploring the anti-inflammatory mechanism of baicalein.

THE PROTECTIVE EFFECT OF C23 IN A RAT MODEL OF CARDIAC ARREST AND RESUSCITATION

ABSTRACT

Background : Systemic inflammation acts as a contributor to neurologic deficits after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Extracellular cold-inducible RNA-binding, protein (CIRP) has been demonstrated to be responsible in part for the inflammation through binding to toll-like receptor 4 (TLR4) after cerebral ischemia. The short peptide C23 derived from CIRP has a high affinity for TLR4, we hypothesize that C23 reduces systemic inflammation after CA/CPR by blocking the binding of CIRP to TLR4. Methods : Adult male SD rats in experimental groups were subjected to 5 min of CA followed by resuscitation. C23 peptide (8 mg/kg) or normal saline was injected intraperitoneally at the beginning of the return of spontaneous circulation (ROSC). Results : The expressions of CIRP, TNF-α, IL-6, and IL-1β in serum and brain tissues were significantly increased at 24 h after ROSC ( P < 0.05). C23 treatment could markedly decrease the expressions of TNF-α, IL-6, and IL-1β in serum ( P < 0.05). Besides, it can decrease the expressions of TLR4, TNF-α, IL-6, and IL-1β in the cortex and hippocampus and inhibit the colocalization of CIRP and TLR4 ( P < 0.05). In addition, C23 treatment can reduce the apoptosis of hippocampus neurons ( P < 0.05). Finally, the rats in the C23 group have improved survival rate and neurological prognosis ( P < 0.05). Conclusions: These findings suggest that C23 can reduce systemic inflammation and it has the potential to be developed into a possible therapy for post-CA syndrome.

The Expression of Pyroptosis-Related Gene May Influence the Occurrence, Development, and Prognosis of Uterine Corpus Endometrial Carcinoma

BACKGROUND

Increasing evidence has demonstrated that pyroptosis exerts key roles in the occurrence, development, and prognosis of uterine corpus endometrial carcinoma (UCEC). However, the mechanism of pyroptosis and its predictive value for prognosis remain largely unknown.

METHODS

UCEC data were acquired from The Cancer Genome Atlas (TCGA) database. The differentially expressed genes in UCEC vs. normal cases were selected to perform a weighted correlation network analysis (WGCNA). Forty-two UCEC-associated pyroptosis-related genes were identified via applying differential expression analysis. Protein-protein interaction (PPI) and gene correlation analyses were applied to explore the relationship between 21 UCEC key genes and 42 UCEC-associated pyroptosis-related genes. The expression of 42 UCEC-associated pyroptosis-related genes of different grades was also calculated. The immune environment of UCEC was evaluated. Furthermore, pyroptosis-related genes were filtered out by the co-expression. Univariate and a least absolute shrinkage and selection operator (LASSO) Cox analyses were implemented to yield a pyroptosis-related gene model. We also performed consensus classification to regroup UCEC samples into two clusters. A clinically relevant heatmap and survival analysis curve were implemented to explore the clinicopathological features and relationship between two clusters. Furthermore, a Kaplan-Meier survival analysis was implemented to analyze the risk model.

RESULTS

Twenty-one UCEC key genes and 42 UCEC-associated pyroptosis-related genes were identified. The PPI and gene correlation analysis showed a clear relationship. The expression of 42 UCEC-associated pyroptosis-related genes of different grades was also depicted. A risk model based on pyroptosis-related genes was then developed to forecast overall survival among UCEC patients. Finally, Cox regression analysis verified this model as an independent risk factor for UCEC patients.

CONCLUSIONS

The expression of pyroptosis-related gene may influence UCEC occurrence, development, and prognosis.