Rapamycin Inhibited Pyroptosis and Reduced the Release of IL-1β and IL-18 in the Septic Response

Hydrogen Attenuates Cognitive Impairment in Rat Models of Vascular Dementia by Inhibiting Oxidative Stress and NLRP3 Inflammasome Activation

Vascular dementia (VaD) is the second most common form of dementia worldwide. Oxidative stress and neuroinflammation are important factors contributing to cognitive dysfunction in patients with VaD. The antioxidant and anti-inflammatory properties of hydrogen are increasingly being utilized in neurological disorders, but conventional hydrogen delivery has the disadvantage of inefficiency. Therefore, magnesium silicide nanosheets (MSNs) are used to release hydrogen in vivo in larger quantities and for longer periods of time to explore the appropriate dosage and regimen. In this study, it is observed that hydrogen improved learning and working memory in VaD rats in the Morris water maze and Y-maze, which elicits improved cognitive function. Nissl staining of neurons shows that hydrogen treatment significantly improves edema in neuronal cells. The expression and activation of reactive oxygen species (ROS), Thioredoxin-interacting protein (TXNIP), NOD-like receptor protein 3 (NLRP3), caspase-1, and IL-1β in the hippocampus are measured via ELISA, Western blotting, real-time qPCR, and immunofluorescence. The results show that oxidative stress indicators and inflammasome-related factors are significantly decreased after 7dMSN treatment. Therefore, it is concluded that hydrogen can ameliorate neurological damage and cognitive dysfunction in VaD rats by inhibiting ROS/NLRP3/IL-1β-related oxidative stress and inflammation.

Pyroptosis in septic lung injury: Interactions with other types of cell death

Sepsis is a life-threatening systemic inflammatory response syndrome caused by the host imbalanced response to infection. Lung injury is the most common complication of sepsis and one of the leading causes of patient death. Pyroptosis is a specific programmed cell death characterized by the release of inflammatory cytokines. Appropriate pyroptosis can reduce tissue damage and exert a protective effect against infection during sepsis. However, overactivated pyroptosis results in massive cell death, leading to septic shock, multiple organ dysfunction syndrome, and even an increased risk of secondary infection. Recent studies suggest that pyroptosis can interact with and cross-regulate other types of cell death programs to establish a complex network of cell death, which participates in the occurrence and development of septic lung injury. This review will focus on the interactions between pyroptosis and other types of cell death, including apoptosis, necroptosis, PANoptosis, NETosis, autophagy, and ferroptosis, to summarize the role of pyroptosis in sepsis-induced lung injury, and will discuss the potential therapeutic strategies of targeting pyroptosis during sepsis treatment.

Regulation of alveolar macrophage death in pulmonary fibrosis: a review

Pulmonary fibrosis (PF) is a disease in which excessive extracellular matrix (ECM) accumulation occurs in pulmonary mesenchyme, which induces the destruction of alveolar structures and poor prognosis. Macrophage death is responsible for ECM accumulation after alveolar epithelial injury in PF. Depending on the local micro-environments, macrophages can be polarized to either classically activated (M1) or alternatively activated (M2) macrophage phenotypes. In general, M1 macrophages can promote inflammation and sterilization, stop the continuous damage process and prevent excessive repair, while M2 macrophages are anti-inflammatory and promote tissue repair, and excessive M2 macrophage activity may inhibit the absorption and degradation of ECM. Emerging evidence has revealed that death forms such as pyroptosis mediated by inflammasome affect polarization direction and ultimately lead to the development of PF. Pharmacological manipulation of macrophages death signals may serve as a logical therapeutic strategy for PF. This review will focus on the current state of knowledge regarding the regulation and underlying mechanisms of macrophages and their mediators in the influence of macrophage death on the development of PF. We expect to provide help in developing effective therapeutic strategies in clinical settings.

P2X7 receptor blockade reduces pyroptotic inflammation and promotes phagocytosis in Vibrio vulnificus infection

Vibrio vulnificus, a gram-negative bacterium, causes serious wound infections and septicemia. Once it develops into early phase sepsis, hyperinflammatory immune responses result in poor prognosis in patients. The present study aimed to examine the possible underlying pathogenic mechanism and explore potential agents that could protect against V. vulnificus cytotoxicity. Here, we report that infection of mouse macrophages with V. vulnificus triggers antiphagocytic effects and pyroptotic inflammation via ATP-mediated purinergic P2X7 receptor (P2X7R) signaling. V. vulnificus promoted P2X7-dependent nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 translocation, modulating the expression of the inflammasome sensor NLR family pyrin domain containing 3 (NLRP3), adaptor apoptosis-associated speck-like protein containing a card (ASC), and pyroptotic protein gasdermin D (GSDMD) in mouse macrophages. V. vulnificus induced the NLRP3/caspase-1 inflammasome signaling complex expression that drives GSDMD transmembrane pore formation and secretion of interleukin (IL)-1β, IL-18, and macrophage inflammatory protein-2 (MIP-2). This effect was blocked by P2X7R antagonists, indicating that the P2X7R mediates GSDMD-related pyroptotic inflammation in macrophages through the NF-κB/NLRP3/caspase-1 signaling pathway. Furthermore, blockade of P2X7R reduced V. vulnificus-colony-forming units in the spleen, immune cell infiltration into the skin and lung tissues, and serum concentrations of IL-1β, IL-18, and MIP-2 in mice. These results indicate that P2X7R plays a vital role in mediating phagocytosis by macrophages and pyroptotic inflammation during V. vulnificus infection and provides new opportunities for therapeutic intervention in bacterial infections.

Pyroptosis and airway homeostasis regulation

Pyroptosis is a form of cell death associated with inflammation. In the maintenance of airway homeostasis, pyroptosis goes through activation and assembly of Inflammasome. The pyroptosis pathway is mediated by caspase which activates the pore-forming effect of substrate gasdermin family members. It eventually leads to lysis and release of the cell contents and then induces an inflammatory response. In this process, it participates in airway homeostasis regulation by affecting airway immunity, airway epithelial structure and airway microbiota. Therefore, we discussed the correlation between airway immunity, airway epithelial structure, airway microbiota and the mechanism of pyroptosis to describe the role of pyroptosis in airway homeostasis regulation which is of great significance for understanding the occurrence and treatment of airway inflammatory diseases.

The Interplay Between Autophagy and Regulated Necrosis

Significance: Autophagy is critical to cellular homeostasis. Emergence of the concept of regulated necrosis, such as necroptosis, ferroptosis, pyroptosis, and mitochondrial membrane-permeability transition (MPT)-derived necrosis, has revolutionized the research into necrosis. Both altered autophagy and regulated necrosis contribute to major human diseases. Recent studies reveal an intricate interplay between autophagy and regulated necrosis. Understanding the interplay at the molecular level will provide new insights into the pathophysiology of related diseases. Recent Advances: Among the three forms of autophagy, macroautophagy is better studied for its crosstalk with regulated necrosis. Macroautophagy seemingly can either antagonize or promote regulated necrosis, depending upon the form of regulated necrosis, the type of cells or stimuli, and other cellular contexts. This review will critically analyze recent advances in the molecular mechanisms governing the intricate dialogues between macroautophagy and main forms of regulated necrosis. Critical Issues: The dual roles of autophagy, either pro-survival or pro-death characteristics, intricate the mechanistic relationship between autophagy and regulated necrosis at molecular level in various pathological conditions. Meanwhile, key components of regulated necrosis are also involved in the regulation of autophagy, which further complicates the interrelationship. Future Directions: Resolving the controversies over causation between altered autophagy and a specific form of regulated necrosis requires approaches that are more definitive, where rigorous evaluation of autophagic flux and the development of more reliable and specific methods to quantify each form of necrosis will be essential. The relationship between chaperone-mediated autophagy or microautophagy and regulated necrosis remains largely unstudied. Antioxid. Redox Signal. 38, 550-580.

The inflammasome pathway: A key player in ocular surface and anterior segment diseases

Inflammasomes are multicomplex molecular regulators with an emerging importance in regulating ocular surface and anterior segment health and disease. Key components found in the eye include NF-κB, NLRP3, NLRC4, NLRP6, ASC, IL-1β, IL-18, and caspase-1. The role of NLRP1, NLRC4, AIM2, and NLRP3 inflammasomes in the pathogenesis of infectious ulcers, DED, uveitis, glaucoma, corneal edema, and other diseases is being studied with many developments. Attenuation of these diseases has been explored by blocking various molecules along the inflammasome pathway with agents like NAC, polydatin, calcitriol, glyburide, YVAD, and disulfiram. We provide a background on the inflammasome pathway as it relates to the ocular surface and anterior segment of the eye, discuss the role of inflammasomes in the above diseases in animals and humans, investigate new therapeutic targets, and explore the efficacy of new anti-inflammasome therapies.

HSF1 Alleviates Brain Injury by Inhibiting NLRP3-Induced Pyroptosis in a Sepsis Model

Background

Sepsis, which could cause a systemic inflammatory response, is a life-threatening disease with a high morbidity and mortality rate. There is evidence that brain injury may be related to severe systemic infection induced by sepsis. The brain injury caused by sepsis could increase the risk of mortality in septic patients, which seriously affects the septic patient's prognosis of survival. Although there remains a focus on sepsis research, clinical measures to prevent and treat brain injury in sepsis are not yet available, and the high mortality rate is still a big health burden. Therefore, it is necessary to investigate the new molecules or regulated pathways that can effectively inhibit the progress of sepsis.

Objective

NLR family pyrin domain-containing 3 (NLRP3) increased in the procession of sepsis and functioned as the key regulator of pyroptosis. Heat shock factor 1 (HSF1) can protect organs from multiorgan dysfunction syndrome induced by lipopolysaccharides in mice, and NLRP3 could be inhibited by HSF1 in many organs. However, whether HSF1 regulated NLRP3 in sepsis-induced brain injury, as well as the detailed mechanism of HSF1 in brain injury, remains unknown in the sepsis model. In this research, we try to explore the relationship between HSF1 and NLRP3 in a sepsis model and try to reveal the mechanism of HSF1 inhibiting the process of brain injury.

Methods

In this study, we used wild-type mice and hsf1 ^-/- mice for in vivo research and PC12 cells for in vitro research. Real-time PCR and Western blot were used to analyze the expression of HSF1, NLRP3, cytokines, and pyrolytic proteins. EthD-III staining was chosen to detect the pyroptosis of the hippocampus and PC12 cells.

Results

The results showed that HSF1 is negatively related to pyroptosis. The pyroptosis in cells of brain tissue was significantly increased in the hsf1 ^-/- mouse model compared to hsf1 ^+/+ mice. In PC12 cells, hsf1 siRNA can upregulate pyroptosis while HSF1-transfected plasmid could inhibit the pyroptosis. HSF1 could negatively regulate the NLRP3 pathway in PC12 cells, while hsf1 siRNA enhanced the pyroptosis in PC12 cells, which could be reversed by nlrp3 siRNA.

Conclusion

These results imply that HSF1 could alleviate sepsis-induced brain injury by inhibiting pyroptosis through the NLRP3-dependent pathway in brain tissue and PC12 cells, suggesting HSF1 as a potential molecular target for treating brain injury in sepsis clinical studies.

The role of pyroptosis in endothelial dysfunction induced by diseases

Most organs in the body rely on blood flow, and vesicular damage is the leading cause of injury in multiple organs. The endothelium, as the barriers of vessels, play a critical role in ensuring vascular homeostasis and angiogenesis. The rapid development of risk factors in endothelial injuries has been seen in the past decade, such as smoking, infectious, and diabetes mellites. Pyroptotic endothelium is an inflammatory mode of governed endothelial cell death that depend on the metabolic disorder and severe infectious such as atherosclerosis, and sepsis-related acute lung injury, respectively. Pyroptotic endothelial cells need GSDMD cleaved into N- and C-terminal by caspase1, and the cytokines are released by a pore constructed by the N-terminal of GSDMD in the membrane of ECs, finally resulting in severe inflammation and pyroptotic cell death. This review will focus on the patho-physiological and pharmacological pathways of pyroptotic endothelial metabolism in diseases. Overall, this review indicates that pyroptosis is a significant risk factor in diseases and a potential drug target in related diseases.

The role of pyroptosis in endothelial dysfunction induced by diseases

Most organs in the body rely on blood flow, and vesicular damage is the leading cause of injury in multiple organs. The endothelium, as the barriers of vessels, play a critical role in ensuring vascular homeostasis and angiogenesis. The rapid development of risk factors in endothelial injuries has been seen in the past decade, such as smoking, infectious, and diabetes mellites. Pyroptotic endothelium is an inflammatory mode of governed endothelial cell death that depend on the metabolic disorder and severe infectious such as atherosclerosis, and sepsis-related acute lung injury, respectively. Pyroptotic endothelial cells need GSDMD cleaved into N- and C-terminal by caspase1, and the cytokines are released by a pore constructed by the N-terminal of GSDMD in the membrane of ECs, finally resulting in severe inflammation and pyroptotic cell death. This review will focus on the patho-physiological and pharmacological pathways of pyroptotic endothelial metabolism in diseases. Overall, this review indicates that pyroptosis is a significant risk factor in diseases and a potential drug target in related diseases.

Vascular smooth muscle cells in low SYNTAX scores coronary artery disease exhibit proinflammatory transcripts and proteins correlated with IL1B activation

BACKGROUND AND AIMS

The SYNTAX score is clinically validated to stratify number of lesions and pattern of CAD. A better understanding of the underlying molecular mechanisms influencing the pattern and complexity of coronary arteries lesions among CAD patients is needed.

METHODS

Human arterial biopsies from 49 patients (16 low-SYNTAX-score (LSS, <23), 16 intermediate-SYNTAX-score (ISS, 23 to 32) and 17 high-SYNTAX-score (HSS, >32)) were evaluated using Affymetrix GeneChip® Human Genome U133 Plus 2.0 microarray. The data were validated by Next-Generation Sequencing (NGS). Primary VSMC from patients with low and high SYNTAX scores were isolated and compared using immunohistochemistry, qPCR and immunoblotting to confirm mRNA and proteomic results.

RESULTS

The IL1B was verified as the top upstream regulator of 47 inflammatory DEGs in LSS patients and validated by another sets of patient samples using NGS analysis. The upregulated expression of IL1B was translated to increased level of IL1β protein in the LSS tissue based on immunohistochemical quantitative analysis. Plausibility of idea that IL1B in the arterial wall could be originated from VSMC was checked by exposing culture to proinflammatory conditions where IL1B came out as the top DEG (logFC = 7.083, FDR = 1.38 × 10-114). The LSS patient-derived primary VSMCs confirmed higher levels of IL1B mRNA and protein.

CONCLUSIONS

LSS patients could represent a group of patients where IL1B could play a substantial role in disease pathogenesis. The LSS group could represent a plausible cohort of patients for whom anti-inflammatory therapy could be considered.

Ceramide induces pyroptosis through TXNIP/NLRP3/GSDMD pathway in HUVECs

Background

Pyroptosis of endothelial cells is a new cause of endothelial dysfunction in multiple diseases. Ceramide acts as a potential bioactive mediator of inflammation and increases vascular endothelial permeability in many diseases, whether it can aggravate vascular endothelial injury by inducing cell pyroptosis remains unknown. This study was established to explore the effects of C8-ceramide (C8-Cer) on human umbilical vein vascular endothelial cells (HUVECs) and its possible underlying mechanism.

Methods

HUVECs were exposed to various concentrations of C8-Cer for 12 h, 24 h, 48 h. The cell survival rate was measured using the cell counting kit-8 assay. Western blotting and Real-time polymerase chain reaction (RT-PCR) were used to detect the pyroptosis-releated protein and mRNA expressions, respectively. Caspase-1 activity assay was used to detect caspase-1 activity. Hoechst 33342/propidium iodide double staining and flow cytometry were adopted to measure positive staining of cells. Lactate dehydrogenase release assay and enzyme-linked immunosorbent assay were adopted to measure leakage of cellular contents. FITC method was used to detect the permeability of endothelial cells. ROS fluorescence intensity were detected by flow cytometry.

Results

The viability of HUVECs decreased gradually with the increase in ceramide concentration and time. Ceramide upregulated the expression of thioredoxin interacting protein (TXNIP), NLRP3, GSDMD, GSDMD-NT, caspase-1 and Casp1 p20 at the protein and mRNA level in a dose-dependent manner. It also enhanced the PI uptake in HUVECs and upregulated caspase-1 activity. Moreover, it promoted the release of lactate dehydrogenase, interleukin-1β, and interleukin-18. Meanwhile, we found that ceramide led to increased vascular permeability. The inhibitor of NLRP3 inflammasome assembly, MCC950, was able to disrupt the aforementioned positive loop, thus alleviating vascular endothelial cell damage. Interestingly, inhibition of TXNIP either chemically using verapamil or genetically using small interfering RNA (siRNA) can effectively inhibit ceramide-induced pyroptosis and improved cell permeability. In addition, ceramide stimulated reactive oxygen species (ROS) generation. The pretreatment of antioxidant N-acetylcysteine (NAC), ROS scavenger, blocked the expression of pyroptosis markers induced by C8-cer in HUVECs.

Conclusion

The current study demonstrated that C8-Cer could aggravate vascular endothelial cell damage and increased cell permeability by inducing cell pyroptosis. The results documented that the ROS-dependent TXNIP/NLRP3/GSDMD signalling pathway plays an essential role in the ceramide-induced pyroptosis in HUVECs.

Role of adiponectin in osteoarthritis

Osteoarthritis (OA) is a widespread and most common joint disease which leads to social cost increasing accompany with aging population. Surgery is often the final treatment option. The major progression of OA includes cartilage degradation caused by chondrocytes metabolism imbalance. So, the molecular mechanisms of action in chondrocytes may provide insights into treatment methods for OA. Adiponectin is an adipokine with many biological functions in the cell metabolism. Numerous studies have illustrated that adiponectin has diverse biological effects, such as inhibition of cell apoptosis. It regulates various functions in different organs, including muscle, adipose tissue, brain, and bone, and regulates skeletal homeostasis. However, the relationship between adiponectin and cell death in the progression of OA needs further investigation. We elaborate the structure and function and the effect of adiponectin and state the correlation and intersection between adiponectin, autophagy, inflammation, and OA. From the perspective of oxidative stress, apoptosis, pyroptosis, and autophagy, we discuss the possible association between adiponectin, chondrocyte metabolism, and inflammatory factor efforts in OA. What’s more, we summarize the possible treatment methods, including the use of adiponectin as a drug target, and highlight the potential future mechanistic research. In this review, we summarize the molecular pathways and mechanisms of action of adiponectin in chondrocyte inflammation and death and the pathogenesis of OA. We also review the research on adiponectin as a target for treating OA. These studies provide a novel perspective to explore more effective treatment options considering the complex interrelationship between inflammation and metabolism in OA.

Ferroptosis in sepsis: The mechanism, the role and the therapeutic potential

Sepsis is a common critical illness in the Intensive care unit(ICU) and its management and treatment has always been a major challenge in critical care medicine. The dysregulated host response to infection, causing systemic multi-organ and multi-system damage is the main pathogenesis. Notably, intense stress during sepsis can lead to metabolic disturbances of ions, lipids and energy in the organism. Ferroptosis is an iron-dependent, non-apoptotic cell death distinguished by a disruption of iron metabolism and iron-dependent accumulation of lipid peroxides. Mounting researches have established that ferroptosis has an essential part in anti-inflammatory and sepsis, and drugs targeting ferroptosis-related molecules, such as ferroptosis inhibitors, are gradually proving their effectiveness in sepsis. This paper summarizes and reviews the pathogenesis of ferroptosis, its regulatory network, and its vital involvement in the initiation of sepsis and related organ damage, and finally discusses the possible target drugs provided by the above mechanisms, describes the dilemmas as well as the outlook, in the hope of finding more links between ferroptosis and sepsis and providing new perspectives for the future treatment of sepsis.

Gasdermins in Innate Host Defense Against Entamoeba histolytica and Other Protozoan Parasites

Gasdermins (GSDMs) are a group of proteins that are cleaved by inflammatory caspases to induce pore formation in the plasma membrane to cause membrane permeabilization and lytic cell death or pyroptosis. All GSDMs share a conserved structure, containing a cytotoxic N-terminal (NT) pore-forming domain and a C-terminal (CT) repressor domain. Entamoeba histolytica (Eh) in contact with macrophages, triggers outside-in signaling to activate inflammatory caspase-4/1 via the noncanonical and canonical pathway to promote cleavage of gasdermin D (GSDMD). Cleavage of GSDMD removes the auto-inhibition that masks the active pore-forming NT domain in the full-length protein by interactions with GSDM-CT. The cleaved NT-GSDMD monomers then oligomerize to form pores in the plasma membrane to facilitate the release of IL-1β and IL-18 with a measured amount of pyroptosis. Pyroptosis is an effective way to counteract intracellular parasites, which exploit replicative niche to avoid killing. To date, most GSDMs have been verified to perform pore-forming activity and GSDMD-induced pyroptosis is rapidly emerging as a mechanism of anti-microbial host defence. Here, we review our comprehensive and current knowledge on the expression, activation, biological functions, and regulation of GSDMD cleavage with emphases on physiological scenario and related dysfunctions of each GSDM member as executioner of cell death, cytokine secretion and inflammation against Eh and other protozoan parasitic infections.

Electroacupuncture at ST36 (Zusanli) Prevents T-Cell Lymphopenia and Improves Survival in Septic Mice

Purpose

Sepsis is the main cause of death in intensive care unit. Maladaptive cytokine storm and T-cell lymphopenia are critical prognosis predictors of sepsis. Electroacupuncture (EA) is expected to be an effective intervention to prevent sepsis. This study aims to determine the potential of EA at ST36 (Zusanli) to prevent experimental septic mice.

Methods

Mice were randomly assigned into PBS, LPS, or EA+LPS group. EA (0.1 mA, continuous wave, 10 Hz) was performed stimulating the ST36 for 30 min, once a day for 3 days. After the third day, all mice were challenged with PBS or LPS (4 mg/kg) simultaneously. Mice were evaluated for survival, ear temperature, and other clinical symptoms. Lung and small intestine tissue injuries were analyzed by hematoxylin and eosin staining. Bio-Plex cytokine assay was used to analyze the concentration of cytokines. T lymphocytes were analyzed by flow cytometry and Western blot assays. The role of T cells in preventing sepsis by EA was analyzed by using nude mice lacking T lymphocytes.

Results

EA at ST36 improved survival, symptom scores, and ear temperature of endotoxemic mice. EA also improved dramatically pulmonary and intestinal injury by over 50% as compared to untreated mice. EA blunted the inflammatory cytokine storm by inducing a lasting inhibition of the production of major inflammatory factors (TNF-α, IL-1β, IL-5, IL-6, IL-10, IL-17A, eotaxin, IFN-γ, MIP-1β and KC). Flow cytometry and Western blot analyses showed EA significantly reduced T-lymphocyte apoptosis and pyroptosis. Furthermore, T lymphocytes were critical for the effects of EA at ST36 stimulation blunted serum TNF-α levels in wild-type but not in nude mice.

Conclusion

EA halted systemic inflammation and improved survival in endotoxemic mice. These effects are associated with the protective effect of EA on T lymphocytes, and T cells are required in the anti-inflammatory effects of EA in sepsis.

Total astragalosides decrease apoptosis and pyroptosis by inhibiting enterovirus 71 replication in gastric epithelial cells

Enterovirus 71 (EV71) is one of the primary pathogens involved in severe hand, foot and mouth disease in children. EV71 infection causes various types of programmed cell death. However, there are currently no clinically approved specific antiviral drugs for control of EV71 infection. Astragalus membranaceus (AM), a Traditional Chinese medicine, has been used in antiviral therapy in China. The aim of the present study was to determine whether total astragalosides (ASTs), bioactive components of AM, protect against EV. DAPI nuclear staining was used to observe morphological changes of the nucleus and the protective effect of ASTs, which revealed that the nucleus shrank following EV71 infection, while ASTs reversed it. Cell Counting Kit-8 assay found that human normal gastric epithelial cell (GES-1 cell) viability decreased following EV71 infection, while lactate dehydrogenase (LDH) assay showed that EV71 infection induced GES-1 cell damage. Western blotting was used to measure the expression levels of apoptosis and pyroptosis marker protein to determine whether EV71 infection induced apoptosis and pyroptosis in GES-1 cells. Reverse transcription-quantitative PCR was used to determine the anti-EV71 effect of ASTs. The results showed that ASTs protected GES-1 cells from EV71-induced cell apoptosis and pyroptosis. Furthermore, the present data demonstrated that the protective effect of ASTs was exerted by suppressing EV71 replication and release. These findings suggested that ASTs may represent a potential antiviral agent for the treatment of EV71 infection.

Programmed cell death in aortic aneurysm and dissection: A potential therapeutic target

Rupture of aortic aneurysm and dissection (AAD) remains a leading cause of death. Progressive smooth muscle cell (SMC) loss is a crucial feature of AAD that contributes to aortic dysfunction and degeneration, leading to aortic aneurysm, dissection, and, ultimately, rupture. Understanding the molecular mechanisms of SMC loss and identifying pathways that promote SMC death in AAD are critical for developing an effective pharmacologic therapy to prevent aortic destruction and disease progression. Cell death is controlled by programmed cell death pathways, including apoptosis, necroptosis, pyroptosis, and ferroptosis. Although these pathways share common stimuli and triggers, each type of programmed cell death has unique features and activation pathways. A growing body of evidence supports a critical role for programmed cell death in the pathogenesis of AAD, and inhibitors of various types of programmed cell death represent a promising therapeutic strategy. This review discusses the different types of programmed cell death pathways and their features, induction, contributions to AAD development, and therapeutic potential. We also highlight the clinical significance of programmed cell death for further studies.

Transcriptional and Epigenetic Regulation of Gasdermins

Gasdermins (GSDM) are a family of six homologous proteins (GSDMA to E and Pejvakin) in humans. GSDMA-E are pore-forming proteins targeting the plasma membrane to trigger a rapid cell death termed pyroptosis or bacterial membranes to promote antibacterial immune defenses. Activation of GSDM relies on a proteolytic cleavage but is highly dependent on GSDM expression levels. The different GSDM genes have tissue-specific expression pattern although metabolic, environmental signals, cell stress and numerous cytokines modulate their expression levels in tissues. Furthermore, expression of GSDM genes can be modulated by polymorphisms and have been associated with susceptibility to asthma, inflammatory bowel diseases and rhinovirus wheezing illness. Finally, the expression level of GSDMs controls the balance between apoptosis and pyroptosis affecting both the response and the toxicity to chemotactic drugs and antitumoral treatments. Numerous cancer demonstrate positive or negative modulation of GSDM expression levels correlating with distinct tumor-specific prognosis. In this review, we present the transcriptional and epigenetic mechanisms controlling GSDM levels and their functional consequences in asthma, infection, cancers and inflammatory bowel disease to highlight how this first layer of regulations has key consequences on disease susceptibility and response to treatment.

Rapamycin inhibits LOC102553434-mediated pyroptosis to improve lung injury induced by limb ischemia-reperfusion

Limb ischemia reperfusion (I/R) triggers local or systemic injury, and whether the process is mediated by pyroptosis remains unclear, we aimed to explore whether pyroptosis was involved in the process of rapamycin alleviating lung injury induced by I/R and investigate the molecular mechanisms. The histopathology of lung injury induced by I/R was confirmed by hematoxylin-eosin (HE) staining, and malondialdehyde (MDA), superoxide dismutase (SOD), and the expression of pyroptosis related molecules were detected. RNA sequencing was used to mine key long non-coding RNAs (lncRNAs). The model of lipopolysaccharide (LPS)-induced L2 cell damage was also used to explore the effect and mechanism of rapamycin on lncRNA. Rapamycin treatment alleviated I/R-induced lung histopathologically injury and increased the concentration of MDA while decreased activity of SOD and expression of NLRP3, Caspase-1, interleukin-1β (IL-1β), and IL-18 in rat. A total of 63 differentially expressed lncRNAs (DElncRNAs) were identified from IR + Rap group compared with IR group, and these DElncRNAs were mainly involved in cell adhesion molecules (CAMs) and endocytosis pathway. The lncRNA LOC102553434 and its target gene MMP9 were most significantly up-regulated in I/R-injured rat. In vitro experiments showed that LPS induction caused a significant increase in LOC102553434, MMP9, IL-1β, and IL-18 in L2 cells, but rapamycin treatment significantly reversed the effects. After interfering with the expression of LOC102553434 in the LPS-injured cells pretreated with rapamycin, cell proliferation significantly increased, and the expression of MMP, NLRP3 and caspase-1 were significantly decreased. Rapamycin protects the lung from limb I/R injury by regulating LOC102553434 expression and inhibiting pyroptosis pathway. LOC102553434 plays a role in promoting pyroptosis and thus provides a target for clinical treatment of I/R-induced lung injury.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02708-9.

Autophagy Regulation on Pyroptosis: Mechanism and Medical Implication in Sepsis

Sepsis is defined as a life-threatening disease involving multiple organ dysfunction caused by dysregulated host responses to infection. To date, sepsis remains a dominant cause of death among critically ill patients. Pyroptosis is a unique form of programmed cell death mediated by the gasdermin family of proteins and causes lytic cell death and release of proinflammatory cytokines. Although there might be some positive aspects to pyroptosis, it is regarded as harmful during sepsis and needs to be restricted. Autophagy was originally characterized as a homeostasis-maintaining mechanism in living cells. In the past decade, its function in negatively modulating pyroptosis and inflammation during sepsis has attracted increased attention. Here, we present a comprehensive review of the regulatory effect of autophagy on pyroptosis during sepsis, including the latest advances in our understanding of the mechanism and signaling pathways involved, as well as the potential therapeutic application in sepsis.

Lipopolysaccharide induces vascular endothelial cell pyroptosis via the SP1/RCN2/ROS signaling pathway

Endothelial cell pyroptosis is a novel cause of endothelial dysfunction in sepsis. Reticulocalbin-2 (RCN2) is involved in regulating vascular inflammation and plays an important role in the cardiovascular system. However, the role of RCN2 in inflammation-induced endothelial cell pyroptosis remains to be explored. Here, we found that RCN2 was upregulated after lipopolysaccharide (LPS) treatment in a concentration- and time-dependent manner. RCN2 knockdown resulted in a significant decrease in pyroptosis, reduced LDH and IL-1β release and ROS production and inhibited the expression of pyroptosis-related proteins (NLRP3, cleaved caspase-1, and cleaved GSDMD) (all p < 0.05). N-acetyl-L-cysteine (NAC) counteracted the effects of RCN2 on pyroptosis (all p < 0.01). The silencing of RCN2 antagonized the inhibitory effect of LPS on the phosphorylation of eNOS (p < 0.05). We predicted and confirmed that specificity protein-1(SP1) could directly bind to the RCN2 promoter and regulate RCN2. RCN2 overexpression rescued the inhibitory effect of SP1 inhibitor on HUVEC pyroptosis induced by LPS (all p < 0.05). These findings suggested that the activation of the SP1/RCN2/ROS signaling pathway could promote LPS-induced endothelial cell pyroptosis.