Cleavage of GSDMD by inflammatory caspases determines pyroptotic cell death. Nature. 2015;526:660-665. [PMID: 26375003 DOI: 10.1038/nature15514]

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Alpha1-antitrypsin impacts innate host-pathogen interactions with Candida albicans by stimulating fungal filamentation

Our immune system possesses sophisticated mechanisms to cope with invading microorganisms, while pathogens evolve strategies to deal with threats imposed by host immunity. Human plasma protein α1-antitrypsin (AAT) exhibits pleiotropic immune-modulating properties by both preventing immunopathology and improving antimicrobial host defence. Genetic associations suggested a role for AAT in candidemia, the most frequent fungal blood stream infection in intensive care units, yet little is known about how AAT influences interactions between Candida albicans and the immune system. Here, we show that AAT differentially impacts fungal killing by innate phagocytes. We observed that AAT induces fungal transcriptional reprogramming, associated with cell wall remodelling and downregulation of filamentation repressors. At low concentrations, the cell-wall remodelling induced by AAT increased immunogenic β-glucan exposure and consequently improved fungal clearance by monocytes. Contrastingly, higher AAT concentrations led to excessive C. albicans filamentation and thus promoted fungal immune escape from monocytes and macrophages. This underscores that fungal adaptations to the host protein AAT can differentially define the outcome of encounters with innate immune cells, either contributing to improved immune recognition or fungal immune escape.

Comprehensive integration of single-cell RNA and transcriptome RNA sequencing to establish a pyroptosis-related signature for improving prognostic prediction of gastric cancer

Cell pyroptosis, a Gasdermin-dependent programmed cell death characterized by inflammasome, plays a complex and dynamic role in Gastric cancer (GC), a serious threat to human health. Therefore, the value of pyroptosis-related genes (PRGs) as prognostic biomarkers and therapeutic indicators for patients needs to be exploited in GC. This study integrates single-cell RNA sequencing (scRNA-seq) dataset GSE183904 with GC transcriptome data from the TCGA database, focusing on the expression and distribution of PRGs in GC at the single-cell level. The prognostic signature of PRGs was established by using Cox and LASSO analyses. The differences in long-term prognosis, immune infiltration, mutation profile, CD274 and response to chemotherapeutic drugs between the two groups were analyzed and evaluated. A tissue array was used to verify the expression of six PRGs, CD274, CD163 and FoxP3. C12orf75, VCAN, RGS2, MKNK2, SOCS3 and TNFAIP2 were successfully screened out to establish a signature to potently predict the survival time of GC patients. A webserver (https://pumc.shinyapps.io/GastricCancer/) for prognostic prediction in GC patients was developed based on this signature. High-risk score patients typically had worse prognoses, resistance to classical chemotherapy, and a more immunosuppressive tumor microenvironment. VCAN, TNFAIP2 and SOCS3 were greatly elevated in the GC while RGS2 and MKNK2 were decreased in the tumor samples. Further, VCAN was positively related to the infiltrations of Tregs and M2 TAMs in GC TME and the CD274 in tumor cells. In summary, a potent pyroptosis-related signature was established to accurately forecast the survival time and treatment responsiveness of GC patients.

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.

Mechanism of dexmedetomidine protection against cisplatin induced acute kidney injury in rats

OBJECTIVE

This study explored the molecular mechanisms by which dexmedetomidine (Dex) alleviates cisplatin (CP)-induced acute kidney injury (AKI) in rats.

METHODS

CP-induced AKI models were established, and Dex was intraperitoneally injected at different concentrations into rats in the model groups. Subsequently, rats were assigned to the control, CP, CP + Dex 10 μg/kg, and CP + Dex 25 μg/kg groups. After weighing the kidneys of the rats, the kidney arterial resistive index was calculated, and CP-induced AKI was evaluated. In addition, four serum biochemical indices were measured: histopathological damage in rat kidneys was detected; levels of inflammatory factors, interleukin (IL)-1β, IL-18, IL-6, and tumor necrosis factor alpha, in kidney tissue homogenate of rats were assessed through enzyme-linked immunosorbent assay (ELISA); and levels of NLRP-3, caspase-1, cleaved caspase-1, gasdermin D (GSDMD), and GSDMD-N in kidney tissues of rats were determined via western blotting.

RESULTS

Dex treatment reduced nephromegaly and serum clinical marker upregulation caused by CP-induced AKI. In addition, hematoxylin and eosin staining revealed that Dex treatment relieved CP-induced kidney tissue injury in AKI rats. ELISA analyses demonstrated that Dex treatment reduced the upregulated levels of proinflammatory cytokines in the kidney tissue of AKI rats induced by CP, thereby alleviating kidney tissue injury. Western blotting indicated that Dex alleviated CP-induced AKI by inhibiting pyroptosis mediated by NLRP-3 and caspase-1.

CONCLUSION

Dex protected rats from CP-induced AKI, and the mechanism may be related to NLRP-3/Caspase-1-mediated pyroptosis.

Bilirubin regulates cell death type by alleviating macrophage mitochondrial dysfunction caused by cigarette smoke extract

OBJECTIVES

To explore the effects and mechanisms of bilirubin on mitochondrial function and type of macrophage cell death after exposure to cigarette smoke extract (CSE).

METHODS

RAW264.7 macrophages were treated with different concentrations of CSE and bilirubin solutions and divided into four groups: control, CSE, bilirubin, and bilirubin + CSE groups. The necrotic and apoptotic states of the macrophages were determined using an Annexin V-fluorescein 5-isothiocyanate/propidium iodide (FITC/PI) staining kit. Cytoplasmic NOD-like receptor family, pyrin domain containing 3 (NLRP3) expression in macrophages was detected by immunofluorescence and the levels of IL-1β and IL-18 in the supernatants of culture medium were detected by enzyme linked immunosorbent assay (ELISA) test. A JC-1 mitochondrial membrane potential detection kit was used to assess mitochondrial membrane damage and the adenosine triphosphate (ATP) assay kit was used to determine intracellular ATP levels. After the macrophages were stained with reactive oxygen species (ROS) specific dye, 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA), the fluorescence intensity and proportion of ROS-positive macrophages were measured using flow cytometry.

RESULTS

We observed that compared with those of 0 μM (control group), concentrations of 5, 10, or 20 μΜ bilirubin significantly decreased cell viability, which was increased by bilirubin exposure below 1 μM. The effect of CSE on macrophage viability was concentration- and time-dependent. Bilirubin of 0.2 μM could alleviate the inhibition of macrophage viability caused by 5% CSE. In addition, bilirubin intervention could reduce the occurrence of necrosis and pyroptosis to a certain extent.

CONCLUSIONS

CSE could cause mitochondrial dysfunction in macrophages, as demonstrated by a decrease in mitochondrial membrane potential and intracellular ATP levels and an increase in ROS production, while bilirubin could relieve mitochondrial dysfunction caused by CSE.

Circ_0036490 and DKK1 competitively bind miR-29a to promote lipopolysaccharides-induced human gingival fibroblasts injury

MicroRNA (miRNA) plays a regulatory role in periodontitis. This study aimed to explore whether miR-29a could affect lipopolysaccharides (LPSs)-induced injury in human gingival fibroblasts (HGFs) through the competitive endogenous RNAs (ceRNA) mechanism. Periodontal ligament (PDL) tissues and HGFs were derived from patients with periodontitis and healthy volunteers. Periodontitis cell model was established by treating HGFs with LPS. Expression levels of circ_0036490, miR-29a, and DKK1 were evaluated by the reverse transcription quantitative real-time PCR (RT-qPCR) method. Western blotting assay was performed to assess protein expression levels of pyroptosis-related proteins and Wnt signalling related proteins. Cell viability was evaluated by cell counting kit-8 (CCK-8) assay. Concentration of lactate dehydrogenase (LDH), interleukin (IL)-1β, and IL-18 were determined by Enzyme-linked immunosorbent assay (ELISA). Pyroptosis rate were determined by flow cytometry assay to evaluate pyroptosis. The interaction between miR-29a and circ_0036490 or DKK1 was verified by dual-luciferase reporter and RNA pull-down assays. MiR-29a expression was lower in PDL tissues of patients with periodontitis than that in healthy group; likewise, miR-29a was also downregulated in LPS-treated HGFs. Overexpression of miR-29a increased cell viability and decreased pyroptosis of HGFs induced by LPS while inhibition of miR-29a exerted the opposite role. MiR-29a binds to circ_0036490 and elevation of circ_0036490 contributed to dysfuntion of LPS-treated HGFs and reversed the protection function of elevated miR-29a. In addition, miR-29a targets DKK1. Overexpression of DKK1 abrogated the effects of overexpressed miR-29a on cell vaibility, pyroptosis, and protein levels of Wnt signalling pathway of LPS-treated HGFs. Circ_0036490 and DKK1 competitively bind miR-29a to promote LPS-induced HGF injury in vitro. Wnt pathway inactivated by LPS was activated by miR-29a. Thence, miR-29a may be a promising target for periodontitis.

NLRP3/1-mediated pyroptosis: beneficial clues for the development of novel therapies for Alzheimer's disease

The inflammasome is a multiprotein complex involved in innate immunity that mediates the inflammatory response leading to pyroptosis, which is a lytic, inflammatory form of cell death. There is accumulating evidence that nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome-mediated microglial pyroptosis and NLRP1 inflammasome-mediated neuronal pyroptosis in the brain are closely associated with the pathogenesis of Alzheimer's disease. In this review, we summarize the possible pathogenic mechanisms of Alzheimer's disease, focusing on neuroinflammation. We also describe the structures of NLRP3 and NLRP1 and the role their activation plays in Alzheimer's disease. Finally, we examine the neuroprotective activity of small-molecule inhibitors, endogenous inhibitor proteins, microRNAs, and natural bioactive molecules that target NLRP3 and NLRP1, based on the rationale that inhibiting NLRP3 and NLRP1 inflammasome-mediated pyroptosis can be an effective therapeutic strategy for Alzheimer's disease.

The monkeypox virus-host interplays

Monkeypox virus (MPXV) is a DNA virus belonging to the Orthopoxvirus genus within the Poxviridae family which can cause a zoonotic infection. The unexpected non-endemic outbreak of mpox in 2022 is considered as a new global threat. It is imperative to take proactive measures, including enhancing our understanding of MPXV's biology and pathogenesis, and developing novel antiviral strategies. The host immune responses play critical roles in defensing against MPXV infection while the virus has also evolved multiple strategies for immune escape. This review summarizes the biological features, antiviral immunity, immune evasion mechanisms, pathogenicity, and prevention strategies for MPXV.

Lipocalin-2-mediated intestinal epithelial cells pyroptosis via NF-κB/NLRP3/GSDMD signaling axis adversely affects inflammation in colitis

Ulcerative colitis (UC) is a major inflammatory bowel disease (IBD) characterized by intestinal epithelium damage. Recently, Lipocalin-2 (LCN2) has been identified as a potential fecal biomarker for patients with UC. However, further investigation is required to explore its pro-inflammatory role in UC and the underlying mechanism. The biological analysis revealed that Lcn2 serves as a putative signature gene in the colon mucosa of patients with UC and its association with the capsase/pyroptosis signaling pathway in UC. In wild-type mice with DSS-induced colitis, LCN2 overexpression in colon mucosa via in vivo administration of Lcn2 overexpression plasmid resulted in exacerbation of colitis symptoms and epithelium damage, as well as increased expression levels of pyroptosis markers (cleaved caspase1, GSDMD, IL-1β, HMGB1 and IL-18). Additionally, we observed downregulation in the expression levels of pyroptosis markers following in vivo silencing of LCN2. However, the pro-inflammatory effect of LCN2 overexpression was effectively restrained in GSDMD-KO mice. Moreover, single-cell RNA-sequencing analysis revealed that Lcn2 was predominantly expressed in the intestinal epithelial cells (IECs) within the colon mucosa of patients with UC. We found that LCN2 effectively regulated pyroptosis events by modulating the NF-κB/NLRP3/GSDMD signaling axis in NCM460 cells stimulated by LPS and ATP. These findings demonstrate the pro-inflammatory role of LCN2 in colon epithelium and provide a potential target for inhibiting pyroptosis in UC.

The role of extracellular vesicles in pyroptosis-mediated infectious and non-infectious diseases

Pyroptosis, a lytic and pro-inflammatory cell death, is important in various pathophysiological processes. Host- and bacteria-derived extracellular vesicles (EVs), as natural nanocarriers messengers, are versatile mediators of intercellular communication between different types of cells. Recently, emerging research has suggested that EVs exhibit multifaceted roles in disease progression by manipulating pyroptosis. This review focuses on new findings concerning how EVs shape disease progression in infectious and non-infectious diseases by regulating pyroptosis. Understanding the characteristics and activity of EVs-mediated pyroptotic death may conducive to the discovery of novel mechanisms and more efficient therapeutic targets in infectious and non-infectious diseases.

Microglia Caspase11 non-canonical inflammasome drives fever

AIM

Animals exhibit physiological changes designed to eliminate the perceived danger, provoking similar symptoms of fever. However, a high-grade fever indicates poor clinical outcomes. Caspase11 (Casp11) is involved in many inflammatory diseases. Whether Casp11 leads to fever remains unclear. In this study, we investigate the role of the preoptic area of the hypothalamus (PO/AH) microglia Casp11 in fever.

METHODS

We perform experiments using a rat model of LPS-induced fever. We measure body temperature and explore the functions of peripheral macrophages and PO/AH microglia in fever signaling by ELISA, immunohistochemistry, immunofluorescence, flow cytometry, macrophage depletion, protein blotting, and RNA-seq. Then, the effects of macrophages on microglia in a hyperthermic environment are observed in vitro. Finally, adeno-associated viruses are used to knockdown or overexpress microglia Casp11 in PO/AH to determine the role of Casp11 in fever.

RESULTS

We find peripheral macrophages and PO/AH microglia play important roles in the process of fever, which is proved by macrophage and microglia depletion. By RNA-seq analysis, we find Casp11 expression in PO/AH is significantly increased during fever. Co-culture and conditioned-culture simulate the induction of microglia Casp11 activation by macrophages in a non-contact manner. Microglia Casp11 knockdown decreases body temperature, pyrogenic factors, and inflammasome, and vice versa.

CONCLUSION

We report that Casp11 drives fever. Mechanistically, peripheral macrophages transmit immune signals via cytokines to microglia in PO/AH, which activate the Casp11 non-canonical inflammasome. Our findings identify a novel player, the microglia Casp11, in the control of fever, providing an explanation for the transmission and amplification of fever immune signaling.

α7-nAChR/P300/NLRP3-regulated pyroptosis mediated poor articular cartilage quality induced by prenatal nicotine exposure in female offspring rats

Nicotine is developmentally toxic. Prenatal nicotine exposure (PNE) affects the development of multiple fetal organs and causes susceptibility to a variety of diseases in offspring. In this study, we aimed to investigate the effect of PNE on cartilage development and osteoarthritis susceptibility in female offspring rats. Wistar rats were orally gavaged with nicotine on days 9-20 of pregnancy. The articular cartilage was obtained at gestational day (GD) 20 and postnatal week (PW) 24, respectively. Further, the effect of nicotine on chondrogenic differentiation was explored by the chondrogenic differentiation model in human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs). The PNE group showed significantly shallower Safranin O staining and lower Collagen 2a1 content of articular cartilage in female offspring rats. Further, we found that PNE activated pyroptosis in the articular cartilage at GD20 and PW24. In vitro experiments revealed that nicotine inhibited chondrogenic differentiation and activated pyroptosis. After interfering with nod-like receptors3 (NLRP3) expression by SiRNA, it was found that pyroptosis mediated the chondrogenic differentiation inhibition of WJ-MSCs induced by nicotine. In addition, we found that α7-nAChR antagonist α-BTX reversed nicotine-induced NLRP3 and P300 high expression. And, P300 SiRNA reversed the increase of NLRP3 mRNA expression and histone acetylation level in its promoter region induced by nicotine. In conclusion, PNE caused chondrodysplasia and poor articular cartilage quality in female offspring rats. PNE increased the histone acetylation level of NLRP3 promoter region by α7-nAChR/P300, which resulting in the high expression of NLRP3. Further, NLRP3 mediated the inhibition of chondrogenic differentiation by activating pyroptosis.

CircPDIA3/miR-449a/XBP1 feedback loop curbs pyroptosis by inhibiting palmitoylation of the GSDME-C domain to induce chemoresistance of colorectal cancer

Although oxaliplatin (OXA) is widely used in the frontline treatment of colorectal cancer (CRC), CRC recurrence is commonly observed due to OXA resistance. OXA resistance is associated with a number of factors, including abnormal regulation of pyroptosis. It is therefore important to elucidate the abnormal regulatory mechanism underlying pyroptosis. Here, we identified that the circular RNA circPDIA3 played an important role in chemoresistance in CRC. CircPDIA3 could induce chemoresistance in CRC by inhibiting pyroptosis both in vitro and in vivo. Mechanistically, RIP, RNA pull-down and co-IP assays revealed that circPDIA3 directly bonded to the GSDME-C domain, subsequently enhanced the autoinhibitory effect of the GSDME-C domain through blocking the GSDME-C domain palmitoylation by ZDHHC3 and ZDHHC17, thereby restraining pyroptosis. Additionally, it was found that the circPDIA3/miR-449a/XBP1 positive feedback loop increased the expression of circPDIA3 to induce chemoresistance. Furthermore, our clinical data and patient-derived tumor xenograft (PDX) models supported the positive association of circPDIA3 with development of chemoresistance in CRC patients. Taken together, our findings demonstrated that circPDIA3 could promote chemoresistance by amplifying the autoinhibitory effect of the GSDME-C domain through inhibition of the GSDME-C domain palmitoylation in CRC. This study provides novel insights into the mechanism of circRNA in regulating pyroptosis and providing a potential therapeutic target for reversing chemoresistance of CRC.

Dexmedetomidine enhances Mitophagy via PINK1 to alleviate hippocampal neuronal Pyroptosis and improve postoperative cognitive dysfunction in elderly rat

Postoperative cognitive dysfunction (POCD) is a common complication in elderly surgical patients, significantly affecting their quality of life. Dexmedetomidine (Dex), an anesthetic, has shown promise in alleviating POCD, but its underlying mechanism remains unclear. This study aims to explore how Dex improves POCD in aged rats by targeting the PINK1-mediated mitochondrial autophagy pathway, reducing caspase-1/11-GSDMD-induced hippocampal neuronal pyroptosis. Transcriptome sequencing identified 300 differentially expressed genes enriched in the mitochondrial autophagy pathway in Dex-treated POCD rat hippocampal tissue, with Pink1 as a key candidate. In a POCD rat model, Dex treatment upregulated hippocampal PINK1 expression. In vitro experiments using H19-7 rat hippocampal neurons revealed that Dex enhanced mitochondrial autophagy and suppressed neuronal pyroptosis by upregulating PINK1. Further mechanistic validation demonstrated that Dex activated PINK1-mediated mitochondrial autophagy, inhibiting caspase-1/11-GSDMD-induced neuronal pyroptosis. In vivo experiments confirmed Dex's ability to reduce caspase-1/11-GSDMD-dependent hippocampal neuronal pyroptosis and improve postoperative cognitive function in aged rats. Dexmedetomidine improves postoperative cognitive dysfunction in elderly rats by enhancing mitochondrial autophagy via PINK1 upregulation, mitigating caspase-1/11-GSDMD-induced neuronal pyroptosis.

Bavachinin, a main compound of Psoraleae Fructus, facilitates GSDMD-mediated pyroptosis and causes hepatotoxicity in mice

Psoraleae Fructus (PF, Psoralea corylifolia L.), a traditional medicine with a long history of application, is widely used clinically for the treatment of various diseases. However, the reports of PF-related adverse reactions, such as hepatotoxicity, phototoxic dermatitis, and allergy, are increasing year by year, with liver injury being the mostly common. Our previous studies have demonstrated that PF and its preparations can cause liver injury in lipopolysaccharide (LPS)-mediated susceptibility mouse model, but the mechanism of PF-related liver injury is unclear. In this study, we showed that PF and bavachinin, a major component of PF, can directly induce the expression of caspase-1 and interleukin-1β (IL-1β), indicating that PF and bavachinin can directly triggered the activation of inflammasome. Furthermore, pretreatment with NLR family pyrin domain-containing 3 (NLRP3), NLR family CARD domain containing 4 (NLRC4) or absent in melanoma 2 (AIM2) inflammasome inhibitors, containing MCC950, ODN TTAGGG (ODN) and carnosol, all significantly reversed bavachinin-induced inflammasome activation. Mechanistically, bavachinin dose-dependently promote Gasdermin D (GSDMD) post-shear activation and then induce mitochondrial reactive oxygen species (mtROS) production and this effect is markedly inhibited by pretreatment with N-Acetylcysteine amide (NAC). In addition, combination treatment of LPS and bavachinin significantly induced liver injury in mice, but not LPS or bavachinin alone, and transcriptome analysis further validated these results. Thus, PF and bavachinin can induce the activation of inflammasome by promoting GSDMD cleavage and cause hepatotoxicity in mice. Therefore, PF, bavachinin, and PF-related preparations should be avoided in patients with inflammasome activation-associated diseases.

Insulin combined with N-acetylcysteine attenuates type 1 diabetes-induced splenic inflammatory injury in canines by inhibiting the MAPKs-NF-κB signaling pathway and pyroptosis

PURPOSE

Type 1 diabetes (T1DM) is a chronic metabolic disorder that can cause damage to multiple organs including the spleen. Sole insulin therapy is not satisfactory. This study aims to investigate the effects and mechanisms of combined treatment with insulin and N-acetylcysteine (NAC) on spleen damage in T1DM canines, in order to identify drugs that may better assist patients in the management of diabetes and its complications.

METHODS

The canine model of T1DM was established by intravenous injection of alloxan (ALX) and streptozotocin (STZ). The therapeutic effects of insulin and NAC were evaluated by clinical manifestations, spleen protein and mRNA expression.

RESULTS

The results indicate that the combined treatment of insulin and NAC can alleviate hyperglycemia and hematologic abnormalities, improve splenic histopathological changes, prevent fibrous tissue proliferation, and glycogen deposition. In addition, we observed that this combination treatment significantly suppressed the protein expression of p-P65/P65 (17.6 %, P < 0.05), NLRP3 (46.8 %, P < 0.05), and p-P38/P38 (37.1 %, P < 0.05) induced by T1DM when compared to insulin treatment alone. Moreover, it also significantly decreased the mRNA expression of TLR4 (45.0 %, P < 0.01), TNF-α (30.3 %, P < 0.05), and NLRP3 (43.3 %, P < 0.05).

CONCLUSIONS

This combination has the potential to mitigate splenic inflammatory injury in T1DM canines by suppressing the activation of MAPKs-NF-κB pathway and pyroptosis. These findings provide a reference for the treatment strategies of diabetes and its complications.

Microglia and Astrocytes Responses Contribute to Alleviating Inflammatory Damage by Repetitive Transcranial Magnetic Stimulation in Rats with Traumatic Brain Injury

Repetitive transcranial magnetic stimulation (rTMS) is a therapeutic strategy that shows promise in ameliorating the clinical sequelae following traumatic brain injury (TBI). These improvements are associated with neuroplastic changes in neurons and their synaptic connections. However, it has been hypothesized that rTMS may also modulate microglia and astrocytes, potentially potentiating their neuroprotective capabilities. This study aims to investigate the effects of high-frequency rTMS on microglia and astrocytes that may contribute to its neuroprotective effects. Feeney's weight-dropping method was used to establish rat models of moderate TBI. To evaluate the neuroprotective effect of high frequency rTMS on rats by observing the synaptic ultrastructure and the level of neuron apoptosis. The levels of several important inflammation-related proteins within microglia and astrocytes were assessed through immunofluorescence staining and western blot. Our findings demonstrate that injured neurons can be rescued through the modulation of microglia and astrocytes by rTMS. This modulation plays a key role in preserving the synaptic ultrastructure and inhibiting neuronal apoptosis. Among microglia, we observed that rTMS inhibited the levels of proinflammatory factors (CD16, IL-6 and TNF-α) and promoted the levels of anti-inflammatory factors (CD206, IL-10 and TNF-β). rTMS also reduced the levels of pyroptosis within microglia and pyroptosis-related proteins (NLRP3, Caspase-1, GSDMD, IL-1β and IL-18). Moreover, rTMS downregulated P75NTR expression and up-regulated IL33 expression in astrocytes. These findings suggest that regulation of microglia and astrocytes is the mechanism through which rTMS attenuates neuronal inflammatory damage after moderate TBI.

The ester-containing prodrug NT-0796 enhances delivery of the NLRP3 inflammasome inhibitor NDT-19795 to monocytic cells expressing carboxylesterase-1

NT-0796 is an ester prodrug which is metabolized by carboxylesterase-1 (CES1) to yield the carboxylic acid NDT-19795, an inhibitor of the NLR family pyrin domain-containing protein 3 (NLRP3) inflammasome. When applied to human monocytes/macrophages which express CES1, however, NT-0796 is much more potent at inhibiting NLRP3 inflammasome activation than is NDT-19795. Comparison of the binding of NDT-19795 and NT-0796 in a cell-based NLRP3 target engagement assay confirms that NDT-19795 is the active species. Moreover, microsomes expressing CES1 efficiently convert NT-0796 to NDT-19795, confirming CES1-dependent activation. To understand the basis for the enhanced potency of the ester prodrug species in human monocytes, we analyzed the accumulation and de-esterification of NT-0796 in cultured cells. Our studies reveal NT-0796 rapidly accumulates in cells, achieving estimated cellular concentrations above those applied to the medium, with concomitant metabolism to NDT-19795 in CES1-expressing cells. Using cells lacking CES1 or a poorly hydrolysable NT-0796 analog demonstrated that de-esterification is not required for NT-0796 to achieve high cellular levels. As a result of a dynamic equilibrium whereby NDT-19795 formed intracellularly is subsequently released to the medium, concentrations of NT-0796 sufficient to inhibit NLRP3 can be completely metabolized to NDT-19795 resulting in a transient pharmacodynamic response. In contrast, when NDT-19795 is applied directly to cells, observed cell-associated levels are below those present in the medium and remain stable over time. Dynamics observed within the context of a closed tissue culture system highlight the utility of NT-0796 as a vehicle for delivering the NDT-19795 acid payload to CES1 expressing cells.

Remdesivir ameliorates ulcerative colitis-propelled cell inflammation and pyroptosis in acetic acid rats by restoring SIRT6/FoxC1 pathway

INTRODUCTION

Ulcerative colitis (UC) is a primary culprit of inflammatory bowel disease that entails prompt and effective clinical intervention. Remdesivir (RDV), a broad-spectrum antiviral nucleotide, has been found to exert anti-inflammatory effects in experimental animals.

AIM

This study investigates the prospective anti-inflammatory merit of RDV on an experimental model of UC. The role of SIRT6/FoxC1 in regulating colonic cell inflammation and pyroptosis is delineated.

METHOD

Rats were challenged with a single intrarectal dose of acetic acid (AA) solution (2 ml; 4 % v/v) to induce colitis. RDV (20 mg/kg, ip) and sulfasalazine (100 mg/kg, po) were administered to rats 14 days before the injection of AA.

RESULTS

Administration of RDV ameliorated colonic cell injury and loss as manifested by improvement of severe colon histopathological mutilation and macroscopic damage and disease activity index scores together with restoration of normal colon weight/length ratio. In addition, RDV alleviated colonic inflammatory reactions, thereby curtailing NF-κB activation and the inflammatory cytokines, TNF-α, IL-18, and IL-1β. Mitigation of colonic oxidative stress and apoptotic reactions were also evident in the setting of RDV treatment. Mechanistically, RDV enhanced the anti-inflammatory cascade, SIRT6/FoxC1, together with curbing the pyroptotic signal, NLRP3/cleaved caspase-1/Gasdermin D-elicited colonic inflammatory cell death.

CONCLUSION

This study reveals, for the first time, the anti-inflammatory effect of RDV against experimental UC. Augmenting SIRT6/FoxC1-mediated repression of colonic inflammation and pyroptosis might advocate the colo-protective potential of RDV.

Palmitoylation of NLRP3 Modulates Inflammasome Activation and Inflammatory Bowel Disease Development

Aberrant activity of NLRP3 has been shown associations with severe diseases. Palmitoylation is a kind of protein post-translational modification, which has been shown to regulate cancer development and the innate immune system. Here, we showed that NLRP3 is palmitoylated at Cys419 and that palmitoyltransferase ZDHHC17 is the predominant enzyme that mediates NLRP3 palmitoylation and promotes NLRP3 activation by interacting with NLRP3 and facilitating NIMA-related kinase 7 (NEK7)-NLRP3 interactions. Blockade of NLRP3 palmitoylation by a palmitoylation inhibitor, 2-bromopalmitate, effectively inhibited NLRP3 activation in vitro. Also, in a dextran sulfate sodium-induced colitis model in mice, 2-bromopalmitate application could attenuate weight loss, improve the survival rate, and rescue pathological changes in the colon of mice. Overall, our study reveals that palmitoylation of NLPR3 modulates inflammasome activation and inflammatory bowel disease development. We propose that drugs targeting NLRP3 palmitoylation could be promising candidates in the treatment of NLRP3-mediated inflammatory diseases.

NLRP3 Inflammasomes: Dual Function in Infectious Diseases

The Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome has been the most distinctive polymer protein complex. After recognizing the endogenous and exogenous danger signals, NLRP3 can cause inflammation by pyroptosis and secretion of mature, bioactive forms of IL-1β and IL-18. The NLRP3 inflammasome is essential in the genesis and progression of infectious illnesses. Herein, we provide a comprehensive review of the NLRP3 inflammasome in infectious diseases, focusing on its two-sided effects. As an essential part of host defense with a protective impact, abnormal NLRP3 inflammasome activation, however, result in a systemic high inflammatory response, leading to subsequent damage. In addition, scientific evidence of small molecules, biologics, and phytochemicals acting on the NLRP3 inflammasome has been reviewed. We believe that the NLRP3 inflammasome helps us understand the pathological mechanism of different stages of infectious diseases and that inhibitors targeting the NLRP3 inflammasome will become a new and valuable research direction for the treatment of infectious diseases.

Therapeutic Targeting of Pattern Recognition Receptors to Modulate Inflammation in Atherosclerosis

Atherosclerosis (AS), a potentially fatal cardiovascular disease (CVD), is a chronic inflammatory condition. The disease's onset and progression are influenced by inflammatory and immunological mechanisms. The innate immune pathways are essential in the progression of AS, as they are responsible for detecting first danger signals and causing long-term changes in immune cells. The innate immune system possesses distinct receptors known as pattern recognition receptors (PRRs) which can identify both pathogen-associated molecular patterns and danger-associated molecular signals. Activation of PRRs initiates the inflammatory response in various physiological systems, such as the cardiovascular system. This review specifically examines the contribution of the innate immune response and PRRs to the formation and advancement of AS. Studying the role of these particular receptors in AS would enhance our understanding of the development of AS and offer novel approaches for directly improving the inflammatory response associated with it.

Mycobacterium intracellulare mediates macrophage pyroptosis by activating AIM2 and NLRP3 inflammasomes

Clinically, the incidence of nontuberculous mycobacteria (NTM) lung disease is on the rise, and Mycobacterium intracellulare (M. intracellulare) has attracted much attention as a common opportunistic pathogen in clinical practice. So it is very important to study its immunopathogenic mechanism. In this study, the mechanism of M. intracellulare induced pyroptosis of macrophage was investigated. As shown in Fig. 1, the secretion of IL-1β and IL-18 in J774A.1 cells increased with time after M. intracellulare infection and was affected by caspase-1 activation and K + efflux, while caspase-1 was significantly expressed in infected cells. Further from Fig. 2, NLRP3,AIM2,ASC proteins were significantly expressed in J774A.1 cells after infection, indicating that the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and absent in melanoma 2 (AIM2) inflammasome were involved in the infection process. In addition, when caspase-1 activity and K + efflux were inhibited, the expression of related proteins was significantly reduced. It indicates that the activation of NLRP3 and AIM2 is regulated by caspase-1 and K+. Figure 3, the percentage of dead cells with cell membrane damage increases after infection and cleavage of GSDMD proteins occurs. In summary, infection of J774A.1 cells with M. intracellulare induces pyroptosis, and this process is mediated by caspase-1. Our study provides information for further understanding of the molecular mechanism of M. intracellulare infection.

Caspase-11 mediated inflammasome activation in macrophages by systemic infection of A. actinomycetemcomitans exacerbates arthritis

Clinical studies have shown that Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is associated with aggressive periodontitis and can potentially trigger or exacerbate rheumatoid arthritis (RA). However, the mechanism is poorly understood. Here, we show that systemic infection with A. actinomycetemcomitans triggers the progression of arthritis in mice anti-collagen antibody-induced arthritis (CAIA) model following IL-1β secretion and cell infiltration in paws in a manner that is dependent on caspase-11-mediated inflammasome activation in macrophages. The administration of polymyxin B (PMB), chloroquine, and anti-CD11b antibody suppressed inflammasome activation in macrophages and arthritis in mice, suggesting that the recognition of lipopolysaccharide (LPS) in the cytosol after bacterial degradation by lysosomes and invasion via CD11b are needed to trigger arthritis following inflammasome activation in macrophages. These data reveal that the inhibition of caspase-11-mediated inflammasome activation potentiates aggravation of RA induced by infection with A. actinomycetemcomitans. This work highlights how RA can be progressed by inflammasome activation as a result of periodontitis-associated bacterial infection and discusses the mechanism of inflammasome activation in response to infection with A. actinomycetemcomitans.

Gasdermin D cysteine residues synergistically control its palmitoylation-mediated membrane targeting and assembly

Gasdermin D (GSDMD) executes the cell death program of pyroptosis by assembling into oligomers that permeabilize the plasma membrane. Here, by single-molecule imaging, we elucidate the yet unclear mechanism of Gasdermin D pore assembly and the role of cysteine residues in GSDMD oligomerization. We show that GSDMD preassembles at the membrane into dimeric and trimeric building blocks that can either be inserted into the membrane, or further assemble into higher-order oligomers prior to insertion into the membrane. The GSDMD residues Cys39, Cys57, and Cys192 are the only relevant cysteines involved in GSDMD oligomerization. S-palmitoylation of Cys192, combined with the presence of negatively-charged lipids, controls GSDMD membrane targeting. Simultaneous Cys39/57/192-to-alanine (Ala) mutations, but not Ala mutations of Cys192 or the Cys39/57 pair individually, completely abolish GSDMD insertion into artificial membranes as well as into the plasma membrane. Finally, either Cys192 or the Cys39/Cys57 pair are sufficient to enable formation of GSDMD dimers/trimers, but they are all required for functional higher-order oligomer formation. Overall, our study unveils a cooperative role of Cys192 palmitoylation-mediated membrane binding and Cys39/57/192-mediated oligomerization in GSDMD pore assembly. This study supports a model in which Gasdermin D oligomerization relies on a two-step mechanism mediated by specific cysteine residues.

Bay-117082 treats sepsis by inhibiting neutrophil extracellular traps (NETs) formation through down-regulating NLRP3/N-GSDMD

During the inflammatory storm of sepsis, a significant quantity of neutrophil extracellular traps (NETs) are generated, which act as a double-edged sword and not only impede the invasion of foreign microorganisms but also exacerbate organ damage. This study provides evidence that NETs can cause damage to alveolar epithelial cells in vitro. The sepsis model developed in this study showed a significant increase in NETs in the bronchoalveolar lavage fluid (BALF). The development of NETs has been shown to increase the lung inflammatory response and aggravate injury to alveolar epithelial cells. Bay-117082, a well-known NF-κB suppressor, is used to modulate inflammation. This analysis revealed that Bay-117082 efficiently reduced total protein concentration, myeloperoxidase activity, and inflammatory cytokines in BALF. Moreover, Bay-117082 inhibited the formation of NETs, which in turn prevented the activation of the pore-forming protein gasdermin D (GSDMD). In summary, these results indicated that excessive NET production during sepsis exacerbated the onset and progression of acute lung injury (ALI). Therefore, Bay-117082 could serve as a novel therapeutic approach for ameliorating sepsis-associated ALI.

Modulating the HSP90 control over NFκB/NLRP3/Caspase-1 axis is a new therapeutic target in the management of liver fibrosis: Insights into the role of TAS-116 (Pimitespib)

Aberrant activation of the NLRP3 inflammasome is recognized to induce a chronic inflammatory response in the liver, ultimately leading to hepatic fibrosis. HSP90 is suggested to regulate NLRP3 activation and its downstream signaling. This study is the first to explore the potential therapeutic role of pimitespib in mitigating liver fibrosis in rats. The results of the study revealed that pimitespib effectively suppressed hepatic inflammation and fibrogenesis by modulating HSP90's control over the NFκB/NLRP3/caspase-1 axis. In vitro experiments demonstrated that pimitespib reduced LDH levels and increased hepatocyte survival, whereas in vivo, it prolonged the survival of rats with hepatic fibrosis. Additionally, pimitespib exhibited improvements in the function and microscopic characteristics of rat livers. Pimitespib effectively inhibited NFκB, which serves as the priming signal for NLRP3 activation. Pimitespib's inhibitory effect on NLRP3, identified as an HSP90 client protein, plays a central role in the observed anti-fibrotic effect. The simultaneous inhibition of both priming and activation signals of NLRP3 by pimitespib led to a reduction in caspase-1 activity and subsequent suppression of the N-terminal fragment of gasdermin D, ultimately constraining hepatocyte pyroptotic cell death. These diverse effects were associated with a decrease in the transcription of inflammatory mediators IL-1β, IL-18, and TNF-α, as well as the fibrogenic mediators TGF-β, TIMP-1, PDGF-BB, and Col1a1. Moreover, pimitespib induced the expression of HSP70, which could further contribute to the repression of fibrosis development. In summary, our findings provide an evolutionary perspective on managing liver fibrosis, positioning pimitespib as a promising candidate for anti-inflammatory and antifibrotic therapy.

Photocatalytic Carbon Dots-Triggered Pyroptosis for Whole Cancer Cell Vaccines

Manufacturing whole cancer cell vaccines (WCCV) with both biosafety and efficacy is crucial for tumor immunotherapy. Pyroptotic cancer cells, due to their highly immunogenic properties, present a promising avenue for the development of WCCV. However, the successful development of WCCV based on pyroptotic cancer cells is yet to be accomplished. Here, a facile strategy that utilized photocatalytic carbon dots (CDs) to induce pyroptosis of cancer cells for fabricating WCCV is reported. Photocatalytic CDs are capable of generating substantial amounts of hydroxyl radicals and can effectively decrease cytoplasmic pH values under white light irradiation. This process efficiently triggers cancer cell pyroptosis through the reactive oxygen species (ROS)-mitochondria-caspase 3-gasdermin E pathway and the proton motive force-driven mitochondrial ATP synthesis pathway. Moreover, in vitro, these photocatalytic CDs-induced pyroptotic cancer cells (PCIP) can hyperactivate macrophage (M0-M1) with upregulation of major histocompatibility complex class II expression. In vivo, PCIP induced specific immune-preventive effects in melanoma and breast cancer mouse models through anticancer immune memory, demonstrating effective WCCV. This work provides novel insights for inducing cancer cell pyroptosis and bridges the gap in the fabrication of WCCV based on pyroptotic cancer cells.

Pyroptosis and the fight against lung cancer

Pyroptosis, a newly characterized type of inflammatory programmed cell death (PCD), is usually triggered by multiple inflammasomes which can recognize different danger or damage-associated molecular patterns (DAMPs), leading to the activation of caspase-1 and the cleavage of gasdermin D (GSDMD). Gasdermin family pore-forming proteins are the executers of pyroptosis and are normally maintained in an inactive state through auto-inhibition. Upon caspases mediated cleavage of gasdermins, the pro-pyroptotic N-terminal fragment is released from the auto-inhibition of C-terminal fragment and oligomerizes, forming pores in the plasma membrane. This results in the secretion of interleukin (IL)-1β, IL-18, and high-mobility group box 1 (HMGB1), generating osmotic swelling and lysis. Current therapeutic approaches including chemotherapy, radiotherapy, molecularly targeted therapy and immunotherapy for lung cancer treatment efficiently force the cancer cells to undergo pyroptosis, which then generates local and systemic antitumor immunity. Thus, pyroptosis is recognized as a new therapeutic regimen for the treatment of lung cancer. In this review, we briefly describe the signaling pathways involved in pyroptosis, and endeavor to discuss the antitumor effects of pyroptosis and its potential application in lung cancer therapy, focusing on the contribution of pyroptosis to microenvironmental reprogramming and evocation of antitumor immune response.

Capsaicin alleviates acute alcohol-induced pyroptosis by activating ESCRT-III-dependent cell membrane repair in hepatocytes

Capsaicin (CAP), the active ingredient in hot chilli peppers, has anti-inflammatory and hepatoprotection effects. Acute alcoholic liver injury (AALI) is liver damage caused by acute alcohol abuse, which can lead to severe liver lesions and even be life-threatening. Pyroptosis is inflammation-related programmed cell death characterized by membrane rupture and plays a key role in AALI. The endosomal sorting complexes required for transport (ESCRT) proteins can gather at damaged areas of the membrane to facilitate the process of sealing the membrane. In this study, we found that CAP could relieve acute alcohol-induced pyroptosis of hepatocytes in vitro and in vivo. Mechanically, we found that CAP could alleviate acute alcohol-induced pyroptosis by activating the ESCRT-III-dependent membrane repair machinery. Furthermore, the data showed that CAP induced ESCRT-III protein expression by activating transient receptor potential vanilloid member 1 (TRPV1) on the cell membrane and Ca2+ influx. TRPV1 inhibitor capsazepine (CPZ) inhibited the relief effect of CAP on acute alcohol-induced pyroptosis. Overall, these results showed that CAP might activate ESCRT-III-dependent membrane repair machinery through Ca2+ influx, which is regulated by TRPV1 calcium channels, therefore mitigating acute alcohol-induced pyroptosis. Our research provides a new perspective on a naturally active food product to promote cell repair and relieve AALI.

Electrostimulation Evokes Caspase-3-Activated Fast Cancer Cell Pyroptosis and Its Nuclear Stress Response Pathways

Pyroptosis of programmed cell death has been recognized as a more effective way to inhibit the occurrence and development of tumors than the better-studied apoptosis. However, it is still challenging to quickly and effectively trigger pyroptosis of cancer cells for high-efficacy cancer treatment. Here, we report on the first use of mild constant-potential electrostimulation (cp-ES) to quickly trigger cancer cell pyroptosis with a probability up to ∼91.4% and significantly shortened time (within 1 h), ∼3-6 times faster than typical drug stimulation to induce pyroptosis. We find that the ES-induced cancer cell pyroptosis is through the activated caspase-3 (pathway) cleavage of gasdermin E (GSDME) to form an N-terminal fragment (GSDME-N) and observe nuclear shrinkage and reduction of the number of nucleoli as well as down-/up-regulated expression of two important nucleoproteins of nucleolin and nucleophosmin (NPM1). The study enriches the basic understanding of pyroptosis and provides a new avenue for potential effective treatment of cancer.

Prolonged exposure to NaAsO2 induces thyroid dysfunction and inflammatory injury in Sprague‒Dawley rats, involvement of NLRP3 inflammasome‒mediated pyroptosis

Arsenic, a well-known hazardous toxicant, has been found in recent years to act as an environmental endocrine disruptor that accumulates in various endocrine organs, impeding the normal physiological functions of these organs and altering hormone secretion levels. Moreover, some research has demonstrated a correlation between arsenic exposure and thyroid functions, suggesting that arsenic has a toxicological effect on the thyroid gland. However, the specific type of thyroid gland damage caused by arsenic exposure and its potential molecular mechanism remain poorly understood. In this study, the toxic effects of sodium arsenite (NaAsO2) exposure at different doses (0, 2.5, 5.0 and 10.0 mg/kg bw) and over different durations (12, 24 and 36 weeks) on thyroid tissue and thyroid hormone levels in Sprague‒Dawley (SD) rats were investigated, and the specific mechanisms underlying the effects were also explored. Our results showed that NaAsO2 exposure can cause accumulation of this element in the thyroid tissue of rats. More importantly, chronic exposure to NaAsO2 significantly upregulated the expression of NLRP3 inflammasome-related proteins in thyroid tissue, leading to pyroptosis of thyroid cells and subsequent development of thyroid dysfunction, inflammatory injury, epithelial-mesenchymal transition (EMT), and even fibrotic changes in the thyroid glands of SD rats. These findings increase our understanding of the toxic effects of arsenic exposure on the thyroid gland and its functions.

Igniting hope: Harnessing NLRP3 inflammasome-GSDMD-mediated pyroptosis for cancer immunotherapy

In the contemporary landscape of oncology, immunotherapy, represented by immune checkpoint blockade (ICB) therapy, stands out as a beacon of innovation in cancer treatment. Despite its promise, the therapy's progression is hindered by suboptimal clinical response rates. Addressing this challenge, the modulation of the NLRP3 inflammasome-GSDMD-mediated pyroptosis pathway holds promise as a means to augment the efficacy of immunotherapy. In the pathway, the NLRP3 inflammasome serves as a pivotal molecular sensor that responds to inflammatory stimuli within the organism. Its activation leads to the release of cytokines interleukin 1β and interleukin 18 through the cleavage of GSDMD, thereby forming membrane pores and potentially resulting in pyroptosis. This cascade of processes exerts a profound impact on tumor development and progression, with its function and expression exhibiting variability across different tumor types and developmental stages. Consequently, understanding the specific roles of the NLRP3 inflammasome and GSDMD-mediated pyroptosis in diverse tumors is imperative for comprehending tumorigenesis and crafting precise therapeutic strategies. This review aims to elucidate the structure and activation mechanisms of the NLRP3 inflammasome, as well as the induction mechanisms of GSDMD-mediated pyroptosis. Additionally, we provide a comprehensive overview of the involvement of this pathway in various cancer types and its applications in tumor immunotherapy, nanotherapy, and other fields. Emphasis is placed on the feasibility of leveraging this approach to enhance ICB therapy within the field of immunotherapy. Furthermore, we discuss the potential applications of this pathway in other immunotherapy methods, such as chimeric antigen receptor T-cell (CAR-T) therapy and tumor vaccines.

Pyroptosis leads to loss of centrosomal integrity in macrophages

NLRP3 forms a multiprotein inflammasome complex to initiate the inflammatory response when macrophages sense infection or tissue damage, which leads to caspase-1 activation, maturation and release of the inflammatory cytokines interleukin-1β (IL-1β) and IL-18 and Gasdermin-D (GSDMD) mediated pyroptosis. NLRP3 inflammasome activity must be controlled as unregulated and chronic inflammation underlies inflammatory and autoimmune diseases. Several findings uncovered that NLRP3 inflammasome activity is under the regulation of centrosome localized proteins such as NEK7 and HDAC6, however, whether the centrosome composition or structure is altered during the inflammasome activation is not known. Our data show that levels of the centrosomal scaffold protein pericentrin (PCNT) are reduced upon NLRP3 inflammasome activation via different activators in human and murine macrophages. PCNT loss occurs in the presence of membrane stabilizer punicalagin, suggesting this is not a consequence of membrane rupture. We found that PCNT loss is dependent on NLRP3 and active caspases as MCC950 and pan caspase inhibitor ZVAD prevent its degradation. Moreover, caspase-1 and GSDMD are both required for this NLRP3-mediated PCNT loss because absence of caspase-1 or GSDMD triggers an alternative regulation of PCNT via its cleavage by caspase-3 in response to nigericin stimulation. PCNT degradation occurs in response to nigericin, but also other NLRP3 activators including lysomotropic agent L-Leucyl-L-Leucine methyl ester (LLOMe) and hypotonicity but not AIM2 activation. Our work reveals that the NLRP3 inflammasome activation alters centrosome composition highlighting the need to further understand the role of this organelle during inflammatory responses.

Comprehensive analysis, diagnosis, prognosis, and cordycepin (CD) regulations for GSDME expressions in pan-cancers

The Gasdermin E gene (GSDME) plays roles in deafness and cancers. However, the roles and mechanisms in cancers are complex, and the same gene exhibits different mechanisms and actions in different types of cancers. Online databases, such as GEPIA2, cBioPortal, and DNMIVD, were used to comprehensively analyze GSDME profiles, DNA methylations, mutations, diagnosis, and prognosis in patients with tumor tissues and matched healthy tissues. Western blotting and RT-PCR were used to monitor the regulation of GSDME by Cordycepin (CD) in cancer cell lines. We revealed that GSDME expression is significantly upregulated in eight cancers (ACC, DLBC, GBM, HNSC, LGG, PAAD, SKCM, and THYM) and significantly downregulated in seven cancers (COAD, KICH, LAML, OV, READ, UCES, and UCS). The overall survival was longer only in ACC, but shorter in four cancers, including COAD, KIRC, LIHC, and STAD, when GSDME was highly expressed in cancers compared with the corresponding normal tissues. Moreover, the high expression of GSDME was negatively correlated with the poor prognosis of ACC, while the low expression of GSDME was negatively correlated with the poor prognosis of COAD, suggesting that GSDME might serve as a good prognostic factor in these two cancer types. Accordingly, results indicated that the DNA methylations of those 7 CpG sites constitute a potentially effective signature to distinguish different tumors from adjacent healthy tissues. Gene mutations for GSDME were frequently observed in a variety of tumors, with UCES having the highest frequency. Moreover, CD treatment inhibited GSDME expression in different cancer cell lines, while overexpression of GSDME promoted cell migration and invasion. Thus, we have systematically and successfully clarified the GSDME expression profiles, diagnostic values, and prognostic values in pan-cancers. Targeting GSDME with CD implies therapeutic significance and a mechanism for antitumor roles in some types of cancers via increasing the sensitivity of chemotherapy. Altogether, our study may provide a strategy and biomarker for clinical diagnosis, prognostics, and treatment of cancers by targeting GSDME.

HMGB1 released from pyroptotic vascular endothelial cells promotes immune disorders in exertional heatstroke

BACKGROUND AND OBJECTIVE

Exertional heatstroke (EHS) mainly occurs in healthy young people with rapid onset and high mortality. EHS immune disorders can cause systemic inflammatory responses and multiple organ failure; however, the underlying mechanisms remain unclear. As high mobility group box 1 (HMGB1) is a prototypical alarmin that activates inflammatory and immune responses, this study aimed to investigate the effect and mechanism of HMGB1 in the pathogenesis of EHS.

METHODS

Peripheral blood mononuclear cell (PBMC) transcriptome sequencing of healthy volunteers, classical heatstroke patients, and EHS patients was performed. A mouse model of EHS was established and murine tissue damage was evaluated by H&E staining. HMGB1 localization and release were visualized using immunofluorescence staining. Human umbilical vein endothelial cells (HUVECs) and THP-1 cells were co-cultured to study the effects of HMGB1 on macrophages. A neutralizing anti-HMGB1 antibody was used to evaluate the efficacy of EHS treatment in mice.

RESULTS

Plasma and serum HMGB1 levels were significantly increased in EHS patients or mice. EHS-induced endothelial cell pyroptosis promoted HMGB1 release in mice. HMGB1 derived from endothelial cell pyroptosis enhanced macrophage pyroptosis, resulting in immune disorders under EHS conditions. Administration of anti-HMGB1 markedly alleviated tissue injury and systemic inflammatory responses after EHS.

CONCLUSIONS

The release of HMGB1 from pyroptotic endothelial cells after EHS promotes pyroptosis of macrophages and systemic inflammatory response, and HMGB1-neutralizing antibody therapy has good application prospects for EHS.

Multi-omics characterization of the monkeypox virus infection

Multiple omics analyzes of Vaccinia virus (VACV) infection have defined molecular characteristics of poxvirus biology. However, little is known about the monkeypox (mpox) virus (MPXV) in humans, which has a different disease manifestation despite its high sequence similarity to VACV. Here, we perform an in-depth multi-omics analysis of the transcriptome, proteome, and phosphoproteome signatures of MPXV-infected primary human fibroblasts to gain insights into the virus-host interplay. In addition to expected perturbations of immune-related pathways, we uncover regulation of the HIPPO and TGF-β pathways. We identify dynamic phosphorylation of both host and viral proteins, which suggests that MAPKs are key regulators of differential phosphorylation in MPXV-infected cells. Among the viral proteins, we find dynamic phosphorylation of H5 that influenced the binding of H5 to dsDNA. Our extensive dataset highlights signaling events and hotspots perturbed by MPXV, extending the current knowledge on poxviruses. We use integrated pathway analysis and drug-target prediction approaches to identify potential drug targets that affect virus growth. Functionally, we exemplify the utility of this approach by identifying inhibitors of MTOR, CHUK/IKBKB, and splicing factor kinases with potent antiviral efficacy against MPXV and VACV.

Programmed cell death in hepatocellular carcinoma: mechanisms and therapeutic prospects

Hepatocellular Carcinoma (HCC), the most common primary liver cancer, ranks as the third most common cause of cancer-related deaths globally. A deeper understanding of the cell death mechanisms in HCC is essential for developing more effective treatment strategies. This review explores programmed cell death (PCD) pathways involved in HCC, including apoptosis, necroptosis, pyroptosis, ferroptosis, and immunogenic cell death (ICD). These mechanisms trigger specific cell death cascades that influence the development and progression of HCC. Although multiple PCD pathways are involved in HCC, shared cellular factors suggest a possible interplay between the different forms of cell death. However, the exact roles of different cell death pathways in HCC and which cell death pathway plays a major role remain unclear. This review also highlights how disruptions in cell death pathways are related to drug resistance in cancer therapy, promoting a combined approach of cell death induction and anti-tumor treatment to enhance therapeutic efficacy. Further research is required to unravel the complex interplay between cell death modalities in HCC, which may lead to innovative therapeutic breakthroughs.

Interleukin-17F suppressed colon cancer by enhancing caspase 4 mediated pyroptosis of endothelial cells

The combination of anti-angiogenic treatment and immunotherapy presents a promising strategy against colon cancer. Interleukin-17F (IL-17F) emerges as a critical immune cell cytokine expressed in colonic epithelial cells, demonstrating potential in inhibiting angiogenesis. In order to clarify the roles of IL-17F in the colon cancer microenvironment and elucidate its mechanism, we established a mouse colon carcinoma cell line CT26 overexpressing IL-17F and transplanted it subcutaneously into syngeneic BALB/c mice. We also analyzed induced colon tumor in IL-17F knockout and wild type mice. Our results demonstrated that IL-17F could suppress colon tumor growth in vivo with inhibited angiogenesis and enhanced recruitment of cysteine-cysteine motif chemokine receptor 6 (CCR6) positive immune cells. Additionally, IL-17F suppressed the tube formation, cell growth and migration of endothelial cells EOMA in vitro. Comprehensive bioinformatics analysis of transcriptome profiles between EOMA cells and those treated with three different concentrations of IL-17F identified 109 differentially expressed genes. Notably, a potential new target, Caspase 4, showed increased expressions after IL-17F treatment in endothelial cells. Further molecular validation revealed a novel downstream signaling for IL-17F: IL-17F enhanced Caspase 4/GSDMD signaling of endothelial cells, CT26 cells and CT26 transplanted tumors, while IL-17F knockout colon tumors exhibited decreased Caspase 4/GSDMD signaling. The heightened expression of the GSDMD N-terminus, coupled with increased cellular propidium iodide (PI) uptake and lactate dehydrogenase (LDH) release, revealed that IL-17F promoted pyroptosis of endothelial cells. Altogether, IL-17F could modulate the colon tumor microenvironment with inhibited angiogenesis, underscoring its potential as a therapeutic target for colon cancer.

Nanohybrid-Based Redox Homeostasis Perturbators Escaped from Early Lysosomes toward Amplified Sensitization of Tumor Cells and Photothermally Maneuvered Pyroptosis Therapy

Reactive oxygen species (ROS) hold great potential in tumor pyroptosis therapy, yet they are still limited by short species lifespan and limited diffusion distance. Inducing cells into a metastable state and then applying external energy can effectively trigger pyroptosis, but systemic sensitization still faces challenges, such as limited ROS content, rapid decay, and short treatment windows. Herein, a nanohybrid-based redox homeostasis-perturbator system was designed that synergistically induce early lysosomal escape, autophagy inhibition, and redox perturbation functions to effectively sensitize cells to address these challenges. Specifically, weakly alkaline layered double hydroxide nanosheets (LDH NSs) with pH-responsive degradation properties enabled early lysosomal escape within 4 h, releasing poly(L-dopa) nanoparticles for inducing catechol-quinone redox cycling in the cytoplasm. The intracellular ROS levels were systematically rebounded by 3-4 times in tumor cells and lasted for over 4 h. Subsequently induced lysosomal stress and Ca2+ signaling activation resulted in severe mitochondrial dysfunction, as well as a perilous metastable state. Thereby, sequential near-infrared light was applied to trigger amplified stress through a local photothermal conversion. This led to sufficiently high levels of cleaved caspase-1 and GSDMD activation (2.5-2.8-fold increment) and subsequent pyroptosis response. In addition, OH- released by LDH elevated pH to alleviate the limitation of glutathione depletion by quinones at acidic pH and inhibit protective autophagy. Largely secreted inflammatory factors (2.5-5.6-fold increment), efficient maturation of dendritic cells, and further immune stimulation were boosted for tumor inhibition as a consequence. This study offers a new paradigm and insights into the synergy of internal systematic cellular sensitization and sequential external energy treatment to achieve tumor suppression through pyroptosis.

Proteasome Inhibition Induces Apoptosis Through Simultaneous Inactivation of MCL-1/BCL-XL by NOXA Independent of CHOP and JNK Pathways

Proteasome inhibitors have been employed in the treatment of relapsed multiple myeloma and mantle cell lymphoma. The observed toxicity caused by proteasome inhibitors is a universal phenotype in numerous cancer cells with different sensitivity. In this study, we investigate the conserved mechanisms underlying the toxicity of the proteasome inhibitor bortezomib using gene editing approaches. Our findings utilizing different caspase knocking out cells reveal that bortezomib induces classic intrinsic apoptosis by activating caspase-9 and caspase-3/7, leading to pore-forming protein GSDME cleavage and subsequent lytic cell death or called secondary necrosis, a phenotype also observed in many apoptosis triggers like TNFα plus CHX, DTT and tunicamycin treatment in HeLa cells. Furthermore, through knocking out of nearly all BH3-only proteins including BIM, BAD, BID, BMF and PUMA, we demonstrate that NOXA is the sole BH3-only protein responsible for bortezomib-induced apoptosis. Of note, NOXA is well known for selectively binding to MCL-1 and A1, but our studies utilizing different BH3 mimetics as well as immunoprecipitation assays indicate that, except for the constitutive interaction of NOXA with MCL-1, the accumulation of NOXA after bortezomib treatment allows it to interact with BCL-XL, then simultaneous relieving suppression on apoptosis by both anti-apoptotic proteins BCL-XL and MCL-1. In addition, though bortezomib-induced significant ER stress and JNK activation were observed in the study, further genetic depletion experiments prove that bortezomib-induced apoptosis occurs independently of ER stress-related apoptosis factor CHOP and JNK. In summary, these results provide a solid conclusion about the critical role of NOXA in inactivation of BCL-XL except MCL-1 in bortezomib-induced apoptosis.

Gasdermin-E-mediated pyroptosis drives immune checkpoint inhibitor-associated myocarditis via cGAS-STING activation

Immune checkpoint inhibitor (ICI)-induced myocarditis involves intensive immune/inflammation activation; however, its molecular basis is unclear. Here, we show that gasdermin-E (GSDME), a gasdermin family member, drives ICI-induced myocarditis. Pyroptosis mediated by GSDME, but not the canonical GSDMD, is activated in myocardial tissue of mice and cancer patients with ICI-induced myocarditis. Deficiency of GSDME in male mice alleviates ICI-induced cardiac infiltration of T cells, macrophages, and monocytes, as well as mitochondrial damage and inflammation. Restoration of GSDME expression specifically in cardiomyocytes, rather than myeloid cells, in GSDME-deficient mice reproduces ICI-induced myocarditis. Mechanistically, quantitative proteomics reveal that GSDME-dependent pyroptosis promotes cell death and mitochondrial DNA release, which in turn activates cGAS-STING signaling, triggering a robust interferon response and myocardial immune/inflammation activation. Pharmacological blockade of GSDME attenuates ICI-induced myocarditis and improves long-term survival in mice. Our findings may advance the understanding of ICI-induced myocarditis and suggest that targeting the GSDME-cGAS-STING-interferon axis may help prevent and manage ICI-associated myocarditis.

A Pyroptosis-Inducing Arsenic(III) Nanomicelle Platform for Synergistic Cancer Immunotherapy

Immunogenic cell death (ICD) could activate anti-tumor immune responses, which is highly attractive for improving cancer treatment effectiveness. Here, this work reports a multifunctional arsenic(III) allosteric inhibitor Mech02, which induces excessive accumulation of 1O2 through sensitized biocatalytic reactions, leading to cell pyroptosis and amplified ICD effect. After Mech02 is converted to Mech03, it could actualize stronger binding effects on the allosteric pocket of pyruvate kinase M2, further interfering with the anaerobic glycolysis pathway of tumors. The enhanced DNA damage triggered by Mech02 and the pyroptosis of cancer stem cells provide assurance for complete tumor clearance. In vivo experiments prove nanomicelle Mech02-HA NPs is able to activate immune memory effects and raise the persistence of anti-tumor immunity. In summary, this study for the first time to introduce the arsenic(III) pharmacophore as an enhanced ICD effect initiator into nitrogen mustard, providing insights for the development of efficient multimodal tumor therapy agents.

Microbiota alterations associated with vascular diseases: postbiotics as a next-generation magic bullet for gut-vascular axis

The intestinal microbiota represents a key element in maintaining the homeostasis and health conditions of the host. Vascular pathologies and other risk factors such as aging have been recently associated with dysbiosis. The qualitative and quantitative alteration of the intestinal microbiota hinders correct metabolic homeostasis, causing structural and functional changes of the intestinal wall itself. Impairment of the intestinal microbiota, combined with the reduction of the barrier function, worsen the pathological scenarios of peripheral tissues over time, including the vascular one. Several experimental evidence, collected in this review, describes in detail the changes of the intestinal microbiota in dysbiosis associated with vascular alterations, such as atherosclerosis, hypertension, and endothelial dysfunction, the resulting metabolic disorders and how these can impact on vascular health. In this context, the gut-vascular axis is considered, for the first time, as a merged unit involved in the development and progression of vascular pathologies and as a promising target. Current approaches for the management of dysbiosis such as probiotics, prebiotics and dietary modifications act mainly on the intestinal district. Postbiotics, described as preparation of inanimate microorganisms and/or their components that confers health benefits on the host, represent an innovative strategy for a dual management of intestinal dysbiosis and vascular pathologies. In this context, this review has the further purpose of defining the positive effects of the supplementation of bacterial strains metabolites (short‑chain fatty acids, exopolysaccharides, lipoteichoic acids, gallic acid, and protocatechuic acid) restoring intestinal homeostasis and acting directly on the vascular district through the gut-vascular axis.

Co-exposure of bisphenol A and selenium deficiency induces pyroptosis via ROS/NLRP3 pathway in chicken spleen

Bisphenol A (BPA) is widely applied in plastic products, which will produce immunotoxicity to organisms after spilling in the environment, and become a kind of endocrine disruptor. Selenium (Se) is an essential trace element and plays an important role in maintaining redox homeostasis and immune function. BPA exposure and Se deficiency often occur together in livestock and poultry farming, however, studies on the effects of joint exposure on chicken immunotoxins have not been reported. Therefore, this study established a chicken spleen and MDCC-MSB1 cell model under the combined effects of BPA exposure or/and Se deficiency. Transcriptomic analysis showed that BPA exposure and/or Se deficiency induced differential enrichment of positive regulatory pathways such as NLRP3 inflammatory complex assembly, inflammatory response and cellular oxidative stress response. In the -Se+BPA group, pathological damage was significantly increased, Se content decreased, BPA accumulation, oxidative stress and pyroptosis. Meanwhile, the roles and mechanisms of oxidative stress and pyroptosis in BPA exposure or/and Se deficiency-induced splenic tissue injury were investigated by using IF and qRT-PCR methods. The results showed that joint BPA exposure with Se deficiency resulted in more significant changes in the above outcomes than 1 of them. The oxidative stress inhibitor NAC effectually reduced Se deficiency and BPA-induced oxidative stress and pyroptosis, further suggests that oxidative stress mediated Se deficiency or/and BPA-induced pyroptosis. This study revealed that BPA exposure and Se deficiency induced spleen pyroptosis in chickens via the ROS/NLRP3 pathway. These results provide the theoretical basis for the toxicity of BPA in poultry and enrich the toxicological mechanism of combined exposure of Se deficiency and environmental toxins.

Dying for a cause: The pathogenic manipulation of cell death and efferocytic pathways

Cell death is a natural consequence of infection. However, although the induction of cell death was solely thought to benefit the pathogen, compelling data now show that the activation of cell death pathways serves as a nuanced antimicrobial strategy that couples pathogen elimination with the generation of inflammatory cytokines and the priming of innate and adaptive cellular immunity. Following cell death, the phagocytic uptake of the infected dead cell by antigen-presenting cells and the subsequent lysosomal fusion of the apoptotic body containing the pathogen serve as an important antimicrobial mechanism that furthers the development of downstream adaptive immune responses. Despite the complexity of regulated cell death pathways, pathogens are highly adept at evading them. Here, we provide an overview of the remarkable diversity of cell death and efferocytic pathways and discuss illustrative examples of virulence strategies employed by pathogens, including oral pathogens, to counter their activation and persist within the host.

Neuroprotective role of Carvacrol via Nrf2/HO-1/NLRP3 axis in Rotenone-induced PD mice model

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder whose cause is unclear. Neuroinflammation is recognized as one of the major pathogenic mechanisms involved in the development and progression of PD. NLRP3 inflammasome is the most widely studied inflammatory mediator in various diseases including PD. Several phytoconstituents have shown neuroprotective role in PD. Carvacrol is a phenolic monoterpene commonly found in the essential oils derived from plants belonging to Lamiaceae family. It is well known for its anti-inflammatory and antioxidant properties and has been widely explored in several diseases. In this study, we explored the role of Carvacrol in suppressing neuroinflammation by regulating NLRP3 inflammasome through Nrf2/HO-1 axis and subsequently, inflammatory cytokines like IL-1β, IL-18 in Rotenone induced PD mice model. Three doses (25 mg/kg, 50 mg/kg, 100 mg/kg p.o.) of Carvacrol were administered to, respectively, three groups (LD, MD, HD), one hour after administration of Rotenone (1.5 mg/kg, i.p.), every day, for 21 days. Treatment with Carvacrol ameliorated the motor impairment caused by Rotenone. It alleviated neurotoxicity and reduced inflammatory cytokines. Further, Carvacrol also alleviated oxidative stress and increased antioxidant enzymes. From these results, we show that Carvacrol exerts neuroprotective effects in PD via anti-inflammatory and antioxidant mechanisms and could be a potential therapeutic option in PD.

Yersinia infection induces glucose depletion and AMPK-dependent inhibition of pyroptosis in mice

Nutritional status and pyroptosis are important for host defence against infections. However, the molecular link that integrates nutrient sensing into pyroptosis during microbial infection is unclear. Here, using metabolic profiling, we found that Yersinia pseudotuberculosis infection results in a significant decrease in intracellular glucose levels in macrophages. This leads to activation of the glucose and energy sensor AMPK, which phosphorylates the essential kinase RIPK1 at S321 during caspase-8-mediated pyroptosis. This phosphorylation inhibits RIPK1 activation and thereby restrains pyroptosis. Boosting the AMPK-RIPK1 cascade by glucose deprivation, AMPK agonists, or RIPK1-S321E knockin suppresses pyroptosis, leading to increased susceptibility to Y. pseudotuberculosis infection in mice. Ablation of AMPK in macrophages or glucose supplementation in mice is protective against infection. Thus, we reveal a molecular link between glucose sensing and pyroptosis, and unveil a mechanism by which Y. pseudotuberculosis reduces glucose levels to impact host AMPK activation and limit host pyroptosis to facilitate infection.

Leveraging the redundancy of S-denitrosylases in response to S-nitrosylation of caspases: Experimental strategies and beyond

Redox-based protein posttranslational modifications, such as S-nitrosylation of critical, active site cysteine thiols have garnered significant clinical attention and research interest, reasoning for one of the crucial biological implications of reactive messenger molecule, nitric oxide in the cellular repertoire. The stringency of the S-(de)nitrosylation-based redox switch governs the activity and contribution of several susceptible enzymes in signal transduction processes and diverse pathophysiological settings, thus establishing it as a transient yet reasonable, and regulated mechanism of NO adduction and release. Notably, endogenous proteases like cytosolic and mitochondrial caspases with a molecular weight ranging from 33 to 55 kDa are susceptible to performing this biochemistry in the presence of major oxidoreductases, which further unveils the enormous redox-mediated regulational control of caspases in the etiology of diseases. In addition to advancing the progress of the current state of understanding of 'redox biochemistry' in the field of medicine and enriching the existing dynamic S-nitrosoproteome, this review stands as a testament to an unprecedented shift in the underpinnings for redundancy and redox relay between the major redoxin/antioxidant systems, fine-tuning of which can command the apoptotic control of caspases at the face of nitro-oxidative stress. These intricate functional overlaps and cellular backups, supported rationally by kinetically favorable reaction mechanisms suggest the physiological relevance of identifying and involving such cognate substrates for cellular S-denitrosylases that can shed light on the bigger picture of extensively proposing targeted therapies and redox-based drug designing to potentially alleviate the side effects of NOx/ROS in disease pathogenesis.