Ghrelin alleviates traumatic brain injury-induced acute lung injury through pyroptosis/NF-κB pathway

Focus on brain-lung crosstalk: Preventing or treating the pathological vicious circle between the brain and the lung

Recently, there has been increasing attention to bidirectional information exchange between the brain and lungs. Typical physiological data is communicated by channels like the circulation and sympathetic nervous system. However, communication between the brain and lungs can also occur in pathological conditions. Studies have shown that severe traumatic brain injury (TBI), cerebral hemorrhage, subarachnoid hemorrhage (SAH), and other brain diseases can lead to lung damage. Conversely, severe lung diseases such as acute respiratory distress syndrome (ARDS), pneumonia, and respiratory failure can exacerbate neuroinflammatory responses, aggravate brain damage, deteriorate neurological function, and result in poor prognosis. A brain or lung injury can have adverse effects on another organ through various pathways, including inflammation, immunity, oxidative stress, neurosecretory factors, microbiome and oxygen. Researchers have increasingly concentrated on possible links between the brain and lungs. However, there has been little attention given to how the interaction between the brain and lungs affects the development of brain or lung disorders, which can lead to clinical states that are susceptible to alterations and can directly affect treatment results. This review described the relationships between the brain and lung in both physiological and pathological conditions, detailing the various pathways of communication such as neurological, inflammatory, immunological, endocrine, and microbiological pathways. Meanwhile, this review provides a comprehensive summary of both pharmacological and non-pharmacological interventions for diseases related to the brain and lungs. It aims to support clinical endeavors in preventing and treating such ailments and serve as a reference for the development of relevant medications.

Baicalin and probenecid protect against Glaesserella parasuis challenge in a piglet model

Glaesserella parasuis (G. parasuis) induces vascular damage and systemic inflammation. However, the mechanism by which it causes vascular damage is currently unclear. Baicalin has important anti-inflammatory, antibacterial and immunomodulatory functions. In this study, we explored the ability of baicalin and probenecid to protect against G. parasuis challenge in a piglet model. Sixty piglets were randomly divided into a control group; an infection group; a probenecid group; and 25 mg/kg, 50 mg/kg and 100 mg/kg baicalin groups. The probenecid group and the 25 mg/kg, 50 mg/kg and 100 mg/kg baicalin groups were injected intramuscularly with 20 mg/kg body weight (BW) probenecid and 25 mg/kg BW, 50 mg/kg BW and 100 mg/kg BW baicalin, respectively. All piglets except those from the control group were injected intraperitoneally with 1 × 108 CFU of G. parasuis. The control group was injected intraperitoneally with TSB. The results showed baicalin and probenecid protected piglets against G. parasuis challenge, improved body weight and decreased temperature changes in piglets. Baicalin and probenecid attenuated IL-1β, IL-10, IL-18, TNF-α and IFN-γ mRNA levels in the blood for 48 h, inhibited the production of the nucleosides ATP, ADP, AMP and UMP from 24 to 72 h, reduced Panx-1/P2Y6/P2X7 expression, weakened NF-kB, AP-1, NLRP3/Caspase-1 and ROCK/MLCK/MLC signalling activation, and upregulated VE-cadherin expression in the blood vessels of piglets challenged with G. parasuis. Baicalin and probenecid alleviated pathological tissue damage in piglets induced by G. parasuis. Our results might provide a promising strategy to control and treat G. parasuis infection in the clinical setting.

Parabacteroides goldsteinii enriched by Pericarpium Citri Reticulatae 'Chachiensis' polysaccharides improves colitis via the inhibition of lipopolysaccharide-involved PI3K-Akt signaling pathway

Epidemiological and preclinical studies have indicated a factual association between gut microbiota dysbiosis and high incidence of colitis. Dietary polysaccharides can specifically shift the composition of gut microbiome response to colitis. Here we validated the preventive role of polysaccharides from Pericarpium Citri Reticulatae 'Chachiensis' (PCRCP), a well-known traditional Chinese medicine, in colitis induced by dextrose sodium sulfate (DSS) in both rats and mice. We found that treatment with PCRCP not only significantly reduced DSS-induced colitis via down-regulating colonic inflammatory signaling pathways including PI3K-Akt, NLRs and NF-κB, but also enhanced colonic barrier integrity in rats. These protective activities of PCRCP against DSS-induced injuries in rats were in part due to the modulation of the gut microbiota revealed by both broad-spectrum antibiotic (ABX)-deleted bacterial and non-oral treatments. Furthermore, the improvement of PCRCP on colitis was impaired by intestinal neomycin-sensitive bacteria in DSS-exposed mice. Specifically, in vivo and in vitro treatment with PCRCP led to a highly sensible enrichment in the gut commensal Parabacteroides goldsteinii. Administration of Parabacteroides goldsteinii significantly alleviated typical symptoms of colitis and suppressed the activation of PI3K-Akt-involved inflammatory response in DSS-exposed mice. The anti-colitic effects of Parabacteroides goldsteinii were abolished after the activation of PI3K-Akt signaling pathway by lipopolysaccharide treatment in mice exposed to DSS. This study provides new insights into an anti-colitic mechanism driven by PCRCP and highlights the potential prebiotic of Parabacteroides goldsteinii for the prevention of ulcerative colitis.

Water decoction of Pericarpium citri reticulatae and Amomi fructus ameliorates alcohol-induced liver disease involved in the modulation of gut microbiota and TLR4/NF-κB pathway

Introduction

Alcohol consumption alters the diversity and metabolic activities of gut microbiota, leading to intestinal barrier dysfunction and contributing to the development of alcoholic liver disease (ALD), which is the most prevalent cause of advanced liver diseases. In this study, we investigated the protective effects and action mechanism of an aqueous extraction of Pericarpium citri reticulatae and Amomi fructus (PFE) on alcoholic liver injury.

Methods

C57BL/6 mice were used to establish the mouse model of alcoholic liver injury and orally administered 500 and 1,000 mg/kg/d of PFE for 2 weeks. Histopathology, immunohistochemistry, immunofluorescence, Western blotting, qRT-PCR, and 16S rDNA amplicon sequencing were used to analyze the mechanism of action of PFE in the treatment of alcohol-induced liver injury.

Results

Treatment with PFE significantly improved alcohol-induced liver injury, as illustrated by the normalization of serum alanine aminotransferase, aspartate aminotransferase, total triglyceride, and cholesterol levels in ALD mice in a dose-dependent manner. Administration of PFE not only maintained the intestinal barrier integrity prominently by upregulating mucous production and tight junction protein expressions but also sensibly reversed the dysregulation of intestinal microecology in alcohol-treated mice. Furthermore, PFE treatment significantly reduced hepatic lipopolysaccharide (LPS) and attenuated oxidative stress as well as inflammation related to the TLR4/NF-κB signaling pathway. The PFE supplementation also significantly promoted the production of short-chain fatty acids (SCFAs) in the ALD mice.

Conclusion

Administration of PFE effectively prevents alcohol-induced liver injury and may also regulate the LPS-involved gut-liver axis; this could provide valuable insights for the development of drugs to prevent and treat ALD.

Honokiol as an α-glucosidase inhibitor

Honokiol, a naturally occurring compound from Magnolia obovata Thunb., has many biological activities, but its anti-α-glucosidase activity is still unclear. Therefore, we determined its inhibitory effects against α-glucosidase. Activity assays showed that honokiol was a reversible mixed-type inhibitor of α-glucosidase, and its IC50 value was 317.11 ± 12.86 μM. Fluorescence results indicated that the binding of honokiol to α-glucosidase caused a reduction in α-glucosidase activity. 3D fluorescence and CD spectra results indicated that the binding of honokiol to α-glucosidase caused conformational change in α-glucosidase. Docking simulated the detailed interactions between honokiol and α-glucosidase, including hydrogen and hydrophobic bonds. All findings showed that honokiol could be used as a natural inhibitor to develop α-glucosidase agents.

Inhibition mechanism investigation of quercetagetin as a potential tyrosinase inhibitor

Tyrosinase is one important rate limiting enzyme in melanin synthesis, directly affecting the melanin synthesis. Quercetagetin is one active ingredient from marigold. Thence, the inhibition effects of quercetagetin against tyrosinase were investigated. The results showed quercetagetin could inhibit tyrosinase activity with IC50 value of 0.19 ± 0.01 mM and the inhibition type was a reversible mixed-type. Results of fluorescence quenching showed quercetagetin could quench tyrosinase fluorescence in static process. CD and 3D fluorescence results showed the interaction of quercetagetin to tyrosinase could change tyrosinase conformation to inhibit activity. Moreover, docking revealed details of quercetagetin's interactions with tyrosinase.

Ghrelin alleviates intestinal ischemia-reperfusion injury by activating the GHSR-1α/Sirt1/FOXO1 pathway

Ischemia-reperfusion (IR) injury is primarily characterized by the restoration of blood flow perfusion and oxygen supply to ischemic tissue and organs, but it paradoxically leads to tissue injury aggravation. IR injury is a challenging pathophysiological process that is difficult to avoid clinically and frequently occurs during organ transplantation, surgery, shock resuscitation, and other processes. The major causes of IR injury include increased levels of free radicals, calcium overload, oxidative stress, and excessive inflammatory response. Ghrelin is a newly discovered brain-intestinal peptide with anti-inflammatory and antiapoptotic effects that improve blood supply. The role and mechanism of ghrelin in intestinal ischemia-reperfusion (IIR) injury remain unclear. We hypothesized that ghrelin could attenuate IIR-induced oxidative stress and apoptosis. To investigate this, we established IIR by using a non-invasive arterial clip to clamp the root of the superior mesenteric artery (SMA) in mice. Ghrelin was injected intraperitoneally at a dose of 50 μg/kg 20 min before IIR surgery, and [D-Lys3]-GHRP-6 was injected intraperitoneally at a dose of 12 nmol/kg 20 min before ghrelin injection. We mimicked the IIR process with hypoxia-reoxygenation (HR) in Caco-2 cells, which are similar to intestinal epithelial cells in structure and biochemistry. Our results showed that ghrelin inhibited IIR/HR-induced oxidative stress and apoptosis by activating GHSR-1α. Moreover, it was found that ghrelin activated the GHSR-1α/Sirt1/FOXO1 signaling pathway. We further inhibited Sirt1 and found that Sirt1 was critical for ghrelin-mediated mitigation of IIR/HR injury. Overall, our data suggest that pretreatment with ghrelin reduces oxidative stress and apoptosis to attenuate IIR/HR injury by binding with GHSR-1α to further activate Sirt1.

Effects of cognitive training and behavior modification on aggressive behavior and sleep quality in schizophrenia

Background

Schizophrenia (SCZ) is linked to a heightened risk of impulsive aggression and disturbances in sleep patterns. Cognitive and social cognitive impairments have been connected to aggression, with social cognitive deficits appearing to play a more immediate role. In this investigation, we conducted a retrospective analysis of the impact of cognitive training and sleep interventions on aggressive behavior and the quality of sleep among individuals with SCZ who were hospitalized.

Methods

This study divided 80 hospitalized patients into two groups according to medical advice, namely the normal group and the study group. The control group received routine drug treatment and education; The research group implemented cognitive training and sleep intervention based on the normal group. Collect basic clinical data, aggressive behavior indicators, and sleep quality indicators.

Results

There is no difference in the basic information statistics between the two groups. Both groups can reduce aggressive behavior and improve sleep quality. In the study group, there was a notable decrease in aggressive behavior compared to the control group. Furthermore, the sleep quality in the study group exhibited significant improvement when compared to the control group.

Conclusion

Cognitive training and sleep intervention have been proven to be effective nonpharmacological treatments, effectively reducing aggressive behavior and improving sleep quality.

Pulmonary Effects of Traumatic Brain Injury in Mice: A Gene Set Enrichment Analysis

Acute lung injury occurs in 20-25% of cases following traumatic brain injury (TBI). We investigated changes in lung transcriptome expression post-TBI using animal models and bioinformatics. Employing unilateral controlled cortical impact for TBI, we conducted microarray analysis after lung acquisition, followed by gene set enrichment analysis of differentially expressed genes. Our findings indicate significant upregulation of inflammation-related genes and downregulation of nervous system genes. There was enhanced infiltration of adaptive immune cells, evidenced by positive enrichment in Lung-Th1, CD4, and CD8 T cells. Analysis using the Tabula Sapiens database revealed enrichment in lung-adventitial cells, pericytes, myofibroblasts, and fibroblasts, indicating potential effects on lung vasculature and fibrosis. Gene set enrichment analysis linked TBI to lung diseases, notably idiopathic pulmonary hypertension. A Venn diagram overlap analysis identified a common set of 20 genes, with FOSL2 showing the most significant fold change. Additionally, we observed a significant increase in ADRA1A→IL6 production post-TBI using the L1000 library. Our study highlights the impact of brain trauma on lung injury, revealing crucial gene expression changes related to immune cell infiltration, cytokine production, and potential alterations in lung vasculature and fibrosis, along with a specific spectrum of disease influence.

Fecal Microbiota Transplantation-Mediated Ghrelin Restoration Improves Neurological Functions After Traumatic Brain Injury: Evidence from 16S rRNA Sequencing and In Vivo Studies

This study aimed to investigate how gut microbiota dysbiosis impacts the repair of the blood-brain barrier and neurological deficits following traumatic brain injury (TBI). Through 16S rRNA sequencing analysis, we compared the gut microbiota of TBI rats and normal controls, discovering significant differences in abundance, species composition, and ecological function, potentially linked to Ghrelin-mediated brain-gut axis functionality. Further, in vivo experiments showed that fecal microbiota transplantation or Ghrelin injection could block the intracerebral TNF signaling pathway, enhance GLP-1 expression, significantly reduce brain edema post-TBI, promote the repair of the blood-brain barrier, and improve neurological deficits. However, the TNF signaling pathway activation could reverse these beneficial effects. In summary, our research suggests that by restoring the balance of gut microbiota, the levels of Ghrelin can be elevated, leading to the blockade of intracerebral TNF signaling pathway and enhanced GLP-1 expression, thereby mitigating post-TBI blood-brain barrier disruption and neurological injuries.

Ghrelin in Focus: Dissecting Its Critical Roles in Gastrointestinal Pathologies and Therapies

This review elucidates the critical role of ghrelin, a peptide hormone mainly synthesized in the stomach in various gastrointestinal (GI) diseases. Ghrelin participates in diverse biological functions ranging from appetite regulation to impacting autophagy and apoptosis. In sepsis, it reduces intestinal barrier damage by inhibiting inflammatory responses, enhancing GI blood flow, and modulating cellular processes like autophagy and apoptosis. Notably, in inflammatory bowel disease (IBD), serum ghrelin levels serve as markers for distinguishing between active and remission phases, underscoring its potential in IBD treatment. In gastric cancer, ghrelin acts as an early risk marker, and due to its significant role in increasing the proliferation and migration of gastric cancer cells, the ghrelin-GHS-R axis is poised to become a target for gastric cancer treatment. The role of ghrelin in colorectal cancer (CRC) remains controversial; however, ghrelin analogs have demonstrated substantial benefits in treating cachexia associated with CRC, highlighting the therapeutic potential of ghrelin. Nonetheless, the complex interplay between ghrelin's protective and potential tumorigenic effects necessitates a cautious approach to its therapeutic application. In post-GI surgery scenarios, ghrelin and its analogs could be instrumental in enhancing recovery and reducing complications. This article accentuates ghrelin's multifunctionality, shedding light on its influence on disease mechanisms, including inflammatory responses and cancer progression, and examines its therapeutic potential in GI surgeries and disorders, advocating for continued research in this evolving field.

Pyroptosis: a double-edged sword in lung cancer and other respiratory diseases

Pyroptosis is an active cell death process mediated by gasdermin family proteins including Gasdermin A (GSDMA), Gasdermin B (GSDMB), Gasdermin C (GSDMC), Gasdermin D (GSDMD), Gasdermin E (GSDME, DFNA5), and DFNB59. Emerging evidences have shown that pyroptosis contributes to many pulmonary diseases, especially lung cancer, and pneumonia. The exact roles of pyroptosis and gasdermin family proteins are tremendously intricate. Besides, there are evidences that pyroptosis contributes to these respiratory diseases. However, it often plays a dual role in these diseases which is a cause for concern and makes it difficult for clinical translation. This review will focus on the multifaceted roles of pyroptosis in respiratory diseases.

Cofilin Inhibitor Improves Neurological and Cognitive Functions after Intracerebral Hemorrhage by Suppressing Endoplasmic Reticulum Stress Related-Neuroinflammation

Neuroinflammation after intracerebral hemorrhage (ICH) is a crucial factor that determines the extent of the injury. Cofilin is a cytoskeleton-associated protein that drives neuroinflammation and microglia activation. A novel cofilin inhibitor (CI) synthesized and developed in our lab has turned out to be a potential therapeutic agent for targeting cofilin-mediated neuroinflammation in an in vitro model of ICH and traumatic brain injury. The current study aims to examine the therapeutic potential of CI in a mouse collagenase model of ICH and examine the neurobehavioral outcomes and its mechanism of action. Male mice were subjected to intrastriatal collagenase injection to induce ICH, and sham mice received needle insertion. Various concentrations (25, 50, and 100 mg/kg) of CI were administered to different cohorts of the animals as a single intravenous injection 3 h following ICH and intraperitoneally every 12 h for 3 days. The animals were tested for neurobehavioral parameters for up to 7 days and sacrificed to collect brains for hematoma volume measurement, Western blotting, and immunohistochemistry. Blood was collected for cofilin, TNF-α, and IL-1β assessments. The results indicated that 50 mg/kg CI improved neurological outcomes, reversed post-stroke cognitive impairment, accelerated hematoma resolution, mitigated cofilin rods/aggregates, and reduced microglial and astrocyte activation in mice with ICH. Microglia morphological analysis demonstrated that CI restored the homeostasis ramification pattern of microglia in mice treated with CI. CI suppressed endoplasmic reticulum stress-related neuroinflammation by inhibiting inflammasomes and cell death signaling pathways. We also showed that CI prevented synaptic loss by reviving the pre- and post-synaptic markers. Our results unveil a novel therapeutic approach to treating ICH and open a window for using CI in clinical practice.

Ghrelin attenuates the inflammatory response induced by experimental endotoxemia in mice

OBJECTIVE

Aim: The aim of this research is to assess the anti-inflammatory effect of ghrelin in mice models of polymicrobial sepsis.

PATIENTS AND METHODS

Materials and Methods: 35 male albino Swiss mice, ages 8-12 weeks, weighing 23-33g, were randomly separated into five groups n = 7; normal group was fed their usual diets until time of sampling, the sham group subjected to Anaesthesia and laparotomy, sepsis group subjected to cecal ligation and puncture, vehicle group was given an equivalent volume of intraperitoneal saline injections immediately after cecal ligation and puncture, and the ghrelin group was treated with 80 μg/kg of ghrelin intraperitoneal injections immediately following cecal ligation and puncture. Twenty hours after cecal ligation and puncture, mice were sacrificed; myocardial tissue and serum samples were collected. Serum IL-1β, NF-κB, and TLR4 levels were measured, and inflammatory response's effects on cardiac tissue were evaluated.

RESULTS

Results: The mean serum IL-1β, NF-κB, and TLR4 levels were markedly elevated in the sepsis and vehicle groups than in the normal and sham groups. The mean serum levels of IL-1β, NF-κB, and TLR4 were considerably lower in the ghrelin-treated group than in the vehicle and sepsis groups. Myocardium tissue of the normal and sham groups showed normal architecture. The sepsis and vehicle groups had a severe myocardial injury. The histological characteristics of ghrelin-treated mice differed slightly from those of the normal and sham groups.

CONCLUSION

Conclusions: Our study concluded that ghrelin exerts anti-inflammatory effects in polymicrobial sepsis, as indicated by a considerable decrease in the IL-1β, NF-κB and TLR4 serum levels.

The Role of Gasdermin-D-Mediated Pryoptosis in Organ Injury and Its Therapeutic Implications

Gasdermin-D (GSDMD) belongs to the Gasdermin family (GSDM), which are pore-forming effector proteins that facilitate inflammatory cell death, also known as pyroptosis. This type of programmed cell death is dependent on inflammatory caspase activation, which cleaves gasdermin-D (GSDMD) to form membrane pores and initiates the release of pro-inflammatory cytokines. Pyroptosis plays an important role in achieving immune regulation and homeostasis within various organ systems. The role of GSDMD in pyroptosis has been extensively studied in recent years. In this review, we summarize the role of GSDMD in cellular and organ injury mediated by pyroptosis. We will also provide an outlook on GSDMD therapeutic targets in various organ systems.

Emerging Relevance of Ghrelin in Programmed Cell Death and Its Application in Diseases

Ghrelin, comprising 28 amino acids, was initially discovered as a hormone that promotes growth hormones. The original focus was on the effects of ghrelin on controlling hunger and satiation. As the research further develops, the research scope of ghrelin has expanded to a wide range of systems and diseases. Nevertheless, the specific mechanisms remain incompletely understood. In recent years, substantial studies have demonstrated that ghrelin has anti-inflammatory, antioxidant, antiapoptotic, and other effects, which could affect the signaling pathways of various kinds of programmed cell death (PCD) in treating diseases. However, the regulatory mechanisms underlying the function of ghrelin in different kinds of PCD have not been thoroughly illuminated. This review describes the relationship between ghrelin and four kinds of PCD (apoptosis, necroptosis, autophagy, and pyroptosis) and then introduces the clinical applications based on the different features of ghrelin.

SIRT3 alleviates sepsis-induced acute lung injury by inhibiting pyroptosis via regulating the deacetylation of FoxO3a

OBJECTIVE

This study mainly analyzes the mechanism of SIRT3 alleviating sepsis-induced acute lung injury (ALI) by regulating the deacetylation of FoxO3a and inhibiting pyroptosis.

METHODS

SIRT3-overexpressing and silenced BEAS-2B cells were used to evaluate the effect of SIRT3 on apoptosis in LPS-treated lung epithelial cells. FoxO3a-silenced BEAS-2B cells were also used to verify the mechanism by which SIRT3 inhibited oxidative stress and pyroptosis in vitro in ALI. 3-TYP was used to inhibit the deacetylation function of SIRT3 in vivo. Pyroptosis was assessed by detecting GSDMD-N and LDH efflux.

RESULTS

In CLP-induced ALI mice, GSDMD-N and LDH levels were elevated, pyroptosis was induced. Silencing of SIRT3 exacerbated oxidative stress, NLRP3 activation and pyroptosis, and inhibited the deacetylation of FoxO3a. Overexpression of SIRT3 attenuated pyroptosis, induced deacetylation and restored the expression of FoxO3a and MnSOD. Silencing FoxO3a aggravated pyroptosis. Overexpression of SIRT3 restored the reduced FoxO3a expression and suppressed pyroptosis. 3-TYP blocked the promotion of FoxO3a by SIRT3 and the inhibitory effect of SIRT3 on pyroptosis.

CONCLUSION

The reduction of SIRT3 in sepsis caused hyperacetylation of FoxO3a, which in turn exacerbates oxidative stress and induces pyroptosis of ALI. Increasing the level of SIRT3 promotes FoxO3a through deacetylation, thereby inhibiting pyroptosis and relieving ALI.

Significance of Pyroptosis in Immunoregulation and Prognosis of Patients with Acute Respiratory Distress Syndrome: Evidence from RNA-Seq of Alveolar Macrophages

Objective

This study aimed to investigate the role of pyroptosis in alveolar macrophages regarding the immune microenvironment of acute respiratory distress syndrome (ARDS) and its prognosis.

Methods

ARDS Microarray data were downloaded from Gene Expression Omnibus (GEO). Support vector machine (SVM) and random forest (RF) models were applied to identify hub pyroptosis-related genes (PRGs) with prognostic significance in ARDS. RT-PCR was used to detect the relative expression of PRGs mRNA in alveolar macrophages of ARDS mice. Consensus clustering analysis was conducted based on the expression of the PRGs to identify pyroptosis modification patterns. Bioinformatic algorithms were used to study the immune traits and biological functions of the pyroptosis patterns. Finally, protein-protein interaction (PPI) networks were established to identify hub regulatory proteins with implications for the pyroptosis patterns.

Results

In our study, a total of 12 PRGs with differential expression were obtained. Four hub PRGs, including GPX4, IL6, IL18 and NLRP3, were identified and proven to be predictive of ventilator-free days (VFDS) in ARDS patients. The AUC values of the 4 PRGs were 0.911 (GPX4), 0.879 (IL18), 0.851 (IL6) and 0.841 (NLRP3), respectively. In ARDS mice, GPX4 mRNA decreased significantly, while IL6, IL18, and NLRP3 mRNA increased. Functional analysis revealed that IL6 had the strongest positive correlation with the CCR pathway, while GPX4 exhibited the strongest negative correlation with the T co-inhibition pathway. Based on the expression of the 4 PRGs, three pyroptosis modification patterns representing different immune states were obtained, and pattern C might represent immune storm.

Conclusion

The results showed that pyroptosis plays an important regulatory role in the immune microenvironment of ARDS. This finding provides new insights into the pathogenesis, diagnosis, and treatment of ARDS.

CASP8 Is a Potential Therapeutic Target and Is Correlated with Pyroptosis in Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is a major cause of neurological and psychological problems, especially long-term disability. The purpose of this article is to explore molecular mechanisms linking TBI and pyroptosis with the aim of providing a promising target for future therapeutic interventions.

METHODS

GSE104687 microarray dataset was downloaded from the Gene Expression Omnibus database to obtain differential expressed genes. Meanwhile, pyroptosis-related genes were screened from GeneCards database, and the overlapped genes were considered as the pyroptosis-related genes in TBI. The immune infiltration analysis was conducted to quantify lymphocyte infiltration levels. Moreover, we researched the relevant microRNAs (miRNAs) and transcription factors and investigated the interactions and functions of miRNAs. In addition, the validation set and in vivo experiment further verified the expression of hub gene.

RESULTS

Altogether, we found 240 differential expressed genes in GSE104687 and 254 pyroptosis-related genes in the GeneCards database, and the overlapped gene was caspase 8 (CASP8). Immune Infiltration Analysis suggested the abundance of Tregs cells was significantly higher in TBI group. The NKT and CD8+ Tem were positively correlated with the expression levels of CASP8. The most significant term regarding CASP8 in Reactome pathways analysis was related to NF-kappaB. A total of 20 miRNAs and 25 transcription factors associated with CASP8 were obtained. After investigating the interactions and functions of miRNAs, the NF-kappaB-related signaling pathway was still enriched with a relatively low P-value. The validation set and in vivo experiment further verified the expression of CASP8.

CONCLUSIONS

Our study showed the potential role of CASP8 in pathogenesis of TBI, which may provide a new target for individualized therapy and drug development.

Noncoding RNA-mediated regulation of pyroptotic cell death in cancer

Pyroptosis is a newly discovered form of programmed cell death, which is manifested by DNA fragmentation, cell swelling, cell membrane rupture and leakage of cell contents. Previous studies have demonstrated that pyroptosis is tightly associated with the initiation and development of various cancers, whereas the molecular mechanisms underlying pyroptosis remain obscure. Noncoding RNAs (ncRNAs) are a type of heterogeneous transcripts that are broadly expressed in mammalian cells. Owing to their potency of regulating gene expression, ncRNAs play essential roles in physiological and pathological processes. NcRNAs are increasingly acknowledged as important regulators of the pyroptosis process. Importantly, the crosstalk between ncRNAs and pyroptosis affects various hallmarks of cancer, including cell growth, survival, metastasis and therapeutic resistance. The study of the involvement of pyroptosis-associated ncRNAs in cancer pathobiology has become a hot area in recent years, while there are limited reviews on this topic. Herein, we provide an overview of the complicated roles of ncRNAs, mainly including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), in modulating pyroptosis, with a focus on the underlying mechanisms of the ncRNA-pyroptosis axis in cancer pathogenesis. Finally, we discuss the potential applications and challenges of exploiting pyroptosis-regulating ncRNAs as molecular biomarkers and therapeutic targets in cancer.

The role of regulatory necrosis in traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability in the population worldwide, of which key injury mechanism involving the death of nerve cells. Many recent studies have shown that regulatory necrosis is involved in the pathological process of TBI which includes necroptosis, pyroptosis, ferroptosis, parthanatos, and Cyclophilin D (CypD) mediated necrosis. Therefore, targeting the signaling pathways involved in regulatory necrosis may be an effective strategy to reduce the secondary injury after TBI. Meanwhile, drugs or genes are used as interference factors in various types of regulatory necrosis, so as to explore the potential treatment methods for the secondary injury after TBI. This review summarizes the current progress on regulatory necrosis in TBI.

Potential role of ghrelin in the regulation of inflammation

Several diseases are caused or progress due to inflammation. In the past few years, accumulating evidence suggests that ghrelin, a gastric hormone of 28-amino acid residue length, exerts protective effects against inflammation by modulating the related pathways. This review focuses on ghrelin's anti-inflammatory and potential therapeutic effects in neurological, cardiovascular, respiratory, hepatic, gastrointestinal, and kidney disorders. Ghrelin significantly alleviates excessive inflammation and reduces damage to different target organs mainly by reducing the secretion of inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α), and inhibiting the nuclear factor kappa-B (NF-κB) and NLRP3 inflammasome signaling pathways. Ghrelin also regulates inflammation and apoptosis through the p38 MAPK/c-Jun N-terminal kinase (JNK) signaling pathway; restores cerebral microvascular integrity, and attenuates vascular leakage. Ghrelin activates the phosphoInositide-3 kinase (PI3K)/protein kinase B (Akt) pathway and inhibits inflammatory responses in cardiovascular diseases and acute kidney injury. Some studies show that ghrelin exacerbates colonic and intestinal manifestations of colitis. Interestingly, some inflammatory states, such as non-alcoholic steatohepatitis, inflammatory bowel diseases, and chronic kidney disease, are often associated with high ghrelin levels. Thus, ghrelin may be a potential new therapeutic target for inflammation-related diseases.

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

Association between Traumatic Subarachnoid Hemorrhage and Acute Respiratory Failure in Moderate-to-Severe Traumatic Brain Injury Patients

Acute respiratory failure (ARF) with a high incidence among moderate-to-severe traumatic brain injury (M-STBI) patients plays a pivotal role in worsening neurological outcomes. Traumatic subarachnoid hemorrhage (tSAH) is highly prevalent in M-STBI, which is associated with significant adverse outcomes. In this retrospective cohort study, we aimed to explore the association between the severity of the tSAH and ARF in the M-STBI population. A total of 771 subjects were reviewed. Clinical and neuroimaging data of M-STBI patients were retrospectively collected, and ARF was ascertained retrospectively based on their electronic medical record. The degree of tSAH was classified according to Fisher’s criteria, and the grade of tSAH was dichotomized to a low Fisher grade (Fisher grade 1–2) and a high Fisher grade (Fisher grade 3–4). After exclusion procedures, the data of 695 M-STBI patients were analyzed. A total of 284 (30.8%) had a high Fisher grade on admission. The overall rate of ARF within 48 h upon admission was 34.4% (239/695); it was 29.5% (142/481) and 46.3% (99/214) for the low and high Fisher groups, respectively. In a full cohort, a high Fisher grade was associated with ARF after adjusting for age, gender, GCS, smoking history, comorbidities, multiple injuries, characteristics of TBI, and pulmonary factors (OR 1.78; 95% CI, 1.11–2.85, p = 0.016). This result remained robust in the comparisons after PSM (71/132, 42.8% vs. 53/132, 31.9%; OR, 1.59; 95% CI, 1.02–2.49, p = 0.042). A high Fisher SAH grade exposure on admission is associated with ARF in M-STBI patients.

Lack of STAT6 enhances murine acute lung injury through NLRP3/p38 MAPK signaling pathway in macrophages

Background

Signal transducer and activator of transcription 6 (STAT6) is an intracelluar transcriotion factor and NLRP3 (Nod-like receptor containing a pyrin domain 3) is a component of NLRP3 inflammasome in pyroptotic cells. There was increased activation of STAT6 and expression of NLRP3 in mice with murine acute lung injury (ALI). However, it is unknown their roles in the development of murine ALI. We in this study, investigated the effects of STAT6 signaling on murine ALI and pyroptosis in STAT6 knock-out (KO) mice and macrophages.

Results

STAT6 was activated in the lung tissues of mice 2 days after intratracheal treatmemt with 5 mg/kg LPS. Lack of STAT6 expression in KO mice induced more severe lung inflammation, associated with elevated neutrophil influx and expression of TNF-alpha, IL-6 and IL-1beta in the inflamed lung tissues. In addition, the expression of NLRP3, ASC (apoptosis-associated speck-like protein containing a CARD), p-p38 MAPK (p38 mitogen-activated protein kinase) and ratio of LC3-II/I (microtubule-associated protein-1 light chain-3) was increased, accompanied with the increased polarization of Siglec-F(−) subtype macrophages in KO mice with ALI. Further studies in bone marrow-derived macrophages (BMDMs) revealed that lack of STAT6 increased the expression of NLRP3 and p-p38 MAPK, in association with elevated expression of TNF-alpha, IL-1beta and Calreticulin in LPS-treated KO BMDMs.

Conclusions

Lack of STAT6 exacerbated murine ALI through improving the expression of NLRP3 and activation of p38 MAPK in macrophages. STAT6 has an immune suppressive role in the development of ALI and would be a promising therapeutic target in the treatment of ALI and possibly among patients with acute respiratory distress syndrome (ARDS).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00500-9.

Metadherin silencing results in the inhibition of pyroptosis in lipopolysaccharide/adenosine triphosphate - stimulated renal tubular epithelial cells

Pyroptosis is induced following inflammation via activation of the NLRP3 inflammasome. Lipopolysaccharide (LPS)-induced acute inflammation causes pyroptosis in renal tubular epithelial cells, which aggravates kidney damage and is involved in physiopathological processes in multiple renal diseases. Metadherin (Mtdh) induces inflammation by NLRP3 inflammasome activation. Specifically, it induces inflammatory injury in the kidney by activating the nuclear factor kappa B (NF-κB) signaling pathway, which is involved in NLRP3 inflammasome activation. However, the role of Mtdh in pyroptosis in renal tubular epithelial cells is unclear. Therefore, we investigated whether Mtdh participates in pyroptosis in LPS/adenosine triphosphate (ATP)-treated NRK-52E cells by activating the NLRP3 inflammasome and NF-κB signaling pathway. We induced pyroptosis in NRK-52E cells with LPS/ATP, after which Mtdh was silenced via transfection with small interfering RNA. LPS/ATP upregulated Mtdh expression and induced pyroptosis and NLRP3 inflammasome activation in NRK-52E cells. However, downregulation of Mtdh expression resulted in the alleviation of pyroptosis in LPS/ATP-treated NRK-52E cells. Additionally, activation of the NLRP3 inflammasome and NF-κB signaling pathway was inhibited. This demonstrates that downregulation of Mtdh expression results in the inhibition of pyroptosis in LPS/ATP-treated NRK-52E cells through the suppression of NLRP3 inflammasome activation, which occurs via inhibition of the NF-κB signaling pathway.

Emerging Mechanisms and Targeted Therapy of Pyroptosis in Central Nervous System Trauma

Cell death can occur in different modes, ferroptosis, pyroptosis, apoptosis, and necroptosis. Recent studies have shown that pyroptosis can be effectively regulated and that like necroptosis, pyroptosis has been regarded as a type of programmed cell death. The mechanism of its occurrence can be divided into canonical inflammasome-induced pyroptosis and noncanonical inflammasome-induced pyroptosis. In the past research, pyroptosis has been shown to be closely related to various diseases, such as tumors, neurodegenerative diseases, and central nervous system trauma, and studies have pointed out that in central nervous system trauma, pyroptosis is activated. Furthermore, these studies have shown that the inhibition of pyroptosis can play a role in protecting nerve function. In this review, we summarized the mechanisms of pyroptosis, introduce treatment strategies for targeted pyroptosis in central nervous system trauma, and proposed some issues of targeted pyroptosis in the treatment of central nervous system injury.

Mechanism of miR-126 in hypoxia-reoxygenation-induced cardiomyocyte pyroptosis by regulating HMGB1 and NLRP3 inflammasome

OBJECTIVE

Pyroptosis refers to the programmed cell death. This study evaluated the mechanism of miR-126 in hypoxia-reoxygenation (HR)-induced cardiomyocyte pyroptosis.

METHODS

The HR rat cardiomyocyte models were established. The cell viability, cytotoxicity, and levels of miR-126, pro-caspase-1 (p45), activated caspase-1 (p20/p10), caspase-11, gasdermin D (GSDMD), and GSDMD-N were detected. The cells were transfected with miR-126 mimics to verify the effect on rat cardiomyocyte pyroptosis, and added with HMGB1 inhibitor (Glycyrrhizin) or NLRP3 inhibitor (S3680) to explore the regulatory mechanisms on rat cardiomyocyte pyroptosis. The binding relationship of miR-126 and HMGB1 was explored. The regulatory effect of miR-126 and HMGB1 on HR-stimulated cardiomyocytes was verified through co-transfection with miR-126 mimics and pcDNA3.1-HMGB1.

RESULTS

HR treatment inhibited rat cardiomyocyte viability and increased cytotoxicity. After HR treatment, pro-caspase-1 (p45), activated caspase-1 (p20/p10), caspase-11, GSDMD, and GSDMD-N were elevated in rat cardiomyocytes, while miR-126 was evidently downregulated in rat cardiomyocytes. miR-126 overexpression, and inhibition of HMGB1 or NLRP3 partially reversed HR-induced rat cardiomyocyte cytotoxicity and pyroptosis. miR-126 targeted HMGB1 and HMGB1 overexpression partly reversed the inhibition of miR-126 overexpression on HR-induced cardiomyocyte pyroptosis.

CONCLUSION

miR-126 inhibits HMGB1/NLRP3 activity and the caspase-1/11 activation and reduces the GSDMD-N cleaved from GSDMD, ultimately inhibiting HR-induced cardiomyocyte pyroptosis.

TELOMERASE MEDIATEDS PYROPTOSIS BY NF-κB Chicken telomerase reverse transcriptase mediates LMH cell pyroptosis by regulating the nuclear factor-kappa B signaling pathway

The activation of human telomerase reverse transcriptase is regulated by the nuclear factor kappa B (NF-κB) signaling pathway to various degrees to promote the occurrence and development of tumors. However, the regulatory roles of chicken telomerase reverse transcriptase (chTERT) and the NF-κB signaling pathway in chickens are still elusive, particularly in respect to the regulation of cell pyroptosis. In this study, we found that chTERT upregulated the expression of p65 and p50, downregulated the expression of IκBα, promoted the phosphorylation of p65, p50, and IκBα, and significantly increased the transcript levels of the inflammatory cytokines IFNγ, TNFα, and IL-6 in LMH cells. The activity of NF-κB was significantly decreased after siRNA-mediated chTERT silencing. The expression of chTERT and telomerase activity were also significantly decreased when the NF-κB signaling pathway was blocked by p65 siRNA, MG132 or BAY 11-7082. In cells treated with LPS, the activity of NF-κB signaling pathway and the expression of chTERT were significantly upregulated. All of the results suggested that chTERT and the NF-κB pathway could regulate each other, reciprocally. Moreover, the expression of Caspase-1, NLRP3, GSDMA, IL-18, and IL-1β and caused membrane perforation, suggesting the development of pyroptosis by chTERT in LMH cells. And the expression of caspase-11 did not significantly increased in chTERT overexpression group. Genetic silence of NF-κB p65 or chTERT gene by siRNA suppressed the expression of these proinflammatory cytokines, indicating that chTERT mediates pyroptosis by regulating the NF-κB signaling pathway in LMH cells.

The role of S100B/RAGE-enhanced ADAM17 activation in endothelial glycocalyx shedding after traumatic brain injury

Background

Traumatic brain injury (TBI) remains one of the main causes for disability and death worldwide. While the primary mechanical injury cannot be avoided, the prevention of secondary injury is the focus of TBI research. Present study aimed to elucidate the effects and mechanisms of S100B and its receptor RAGE on mediating secondary injury after TBI.

Methods

This study established TBI animal model by fluid percussion injury in rats, cell model by stretch-injured in astrocytes, and endothelial injury model with conditioned medium stimulation. Pharmacological intervention was applied to interfere the activities of S100B/RAGE/ADAM17 signaling pathway, respectively. The expressions or contents of S100B, RAGE, syndecan-1 and ADAM17 in brain and serum, as well as in cultured cells and medium, were detected by western blot. The distribution of relative molecules was observed with immunofluorescence.

Results

We found that TBI could activate the release of S100B, mostly from astrocytes, and S100B and RAGE could mutually regulate their expression and activation. Most importantly, present study revealed an obvious increase of syndecan-1 in rat serum or in endothelial cultured medium after injury, and a significant decrease in tissue and in cultured endothelial cells, indicating TBI-induced shedding of endothelial glycocalyx. The data further proved that the activation of S100B/RAGE signaling could promote the shedding of endothelial glycocalyx by enhancing the expression, translocation and activity of ADAM17, an important sheddase, in endothelial cells. The damage of endothelial glycocalyx consequently aggravated blood brain barrier (BBB) dysfunction and systemic vascular hyper-permeability, overall resulting in secondary brain and lung injury.

Conclusions

TBI triggers the activation of S100B/RAGE signal pathway. The regulation S100B/RAGE on ADAM17 expression, translocation and activation further promotes the shedding of endothelial glycocalyx, aggravates the dysfunction of BBB, and increases the vascular permeability, leading to secondary brain and lung injury. Present study may open a new corridor for the more in-depth understanding of the molecular processes responsible for cerebral and systemic vascular barrier impairment and secondary injury after TBI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02412-2.

Kindlin-2 Mediates Lipopolysaccharide-Induced Acute Lung Injury Partially via Pyroptosis in Mice

Acute lung injury (ALI) is characteristic of the wholesale destruction of the lung endothelial barrier, which results in protein-rich lung edema, influx of pro-inflammatory leukocytes, and intractable hypoxemia, contributing to high mortality. Kindlin-2 is involved in the process of tumor- and wound healing-associated inflammation. However, the effects of kindlin-2 on lipopolysaccharide (LPS)-induced ALI and its mechanisms remain unknown. In this study, we found that the concentration of kindlin-2 was elevated in the lungs of ALI mice. The specific deletion of kindlin-2 by kindlin-2 siRNA attenuated the severity of lung injury, which was demonstrated by the reduced number of pro-inflammatory cells in bronchoalveolar lavage fluid and lung wet/dry weight ratio, and ameliorated pathologic changes in the lungs of ALI mice. Furthermore, kindlin-2 siRNA decreased the mRNA levels of pro-inflammatory factors (IL-1β, IL-6, and TNF-α) and the protein levels of pyroptosis-related proteins. In vitro studies confirmed that LPS + ATP promoted the expressions of pro-inflammatory factors and pyroptosis-related proteins, which was prevented by kindlin-2 siRNA pretreatment in endothelial cells (ECs). In conclusion, inhibition of kindlin-2 developes protective effects against LPS-induced ALI and the cytotoxicity of ECs, which may depend on blocking pyroptosis.

Cellular and Molecular Signatures of Oxidative Stress in Bronchial Epithelial Cell Models Injured by Cigarette Smoke Extract

Exposure of the airways epithelium to environmental insults, including cigarette smoke, results in increased oxidative stress due to unbalance between oxidants and antioxidants in favor of oxidants. Oxidative stress is a feature of inflammation and promotes the progression of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). Increased oxidative stress leads to exhaustion of antioxidant defenses, alterations in autophagy/mitophagy and cell survival regulatory mechanisms, thus promoting cell senescence. All these events are amplified by the increase of inflammation driven by oxidative stress. Several models of bronchial epithelial cells are used to study the molecular mechanisms and the cellular functions altered by cigarette smoke extract (CSE) exposure, and to test the efficacy of molecules with antioxidant properties. This review offers a comprehensive synthesis of human in-vitro and ex-vivo studies published from 2011 to 2021 describing the molecular and cellular mechanisms evoked by CSE exposure in bronchial epithelial cells, the most used experimental models and the mechanisms of action of cellular antioxidants systems as well as natural and synthetic antioxidant compounds.

Melatonin alleviates lipopolysaccharide (LPS) / adenosine triphosphate (ATP)-induced pyroptosis in rat alveolar Type II cells (RLE-6TN) through nuclear factor erythroid 2-related factor 2 (Nrf2)-driven reactive oxygen species (ROS) downregulation

Pyroptosis has pivotal parts within disease development, rendering this attractive mechanism for novel therapeutics. This investigation aimed at analyzing melatonin roles within pyroptosis together with related mechanistics. RLE-6TN cultures were exposed to varying LPS doses for 4.5 h followed by concomitant culturing in the presence of ATP (5 mM) for 0.5 h to induce injury, and the roles of melatonin, N-Acety-L-cysteine (NAC - a ROS scavenger), ML385 (specific Nrf2 inhibitor) were examined. Apoptosis analysis was performed through lactate dehydrogenase (LDH) activity assays, together with propidium iodide (PI) stain-assay. Intracellular ROS were quantified through 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA). Pyrolysis-associated proteins, such as nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), cysteine aspartate-specific protease-1 P20 (Caspase-1 P20), gasdermin D-N (GSDMD-N), and mature interleukin-1β (IL-1β), were identified through Western blotting. Dataset outcomes demonstrated LPS/ATP induce RLE-6TN cell pyroptosis, while melatonin alleviated this phenomenon, visualized through increased cell survival rate, reduction of LDH discharge and PI⁺ cellular count. Moreover, melatonin effectively reduced NLRP3 inflammasome triggering in RLE-6TN cells. Meanwhile, this study demonstrated melatonin thwarting over NLRP3 inflammasome triggering was depending on ROS. In addition, this study found that melatonin activated Nrf2/Heme Oxygenase-1 (HO-1) pathway, with pyroptotic-inhibiting function of melatonin was reverted through a bespoke Nrf2-inhibitor and siNrf2. In summary, this study concluded that melatonin prevents RLE-6TN cellular pyroptosis through Nrf2-triggered ROS downregulation.

Pulmonary injury as a predictor of cerebral hypoxia in traumatic brain injury: from physiology to physiopathology

Traumatic brain injury is caused by mechanical forces impacting the skull and its internal structures and constitutes one of the main causes of morbidity and mortality in the world. Clinically, severe traumatic brain injury is associated with the development of acute lung injury and so far, few studies have evaluated the cellular, molecular and immunological mechanisms involved in this pathophysiological process. Knowing and investigating these mechanisms allows us to correlate pulmonary injury as a predictor of cerebral hypoxia in traumatic brain injury and to use this finding in decision making during clinical practice. This review aims to provide evidence on the importance of the pathophysiology of traumatic brain injury-acute lung injury, and thus confirm its role as a predictor of cerebral hypoxia, helping to establish an appropriate therapeutic strategy to improve functional outcomes and reduce mortality.

Ketogenic diet reduces early mortality following traumatic brain injury in Drosophila via the PPARγ ortholog Eip75B

Traumatic brain injury (TBI) is a common neurological disorder whose outcomes vary widely depending on a variety of environmental factors, including diet. Using a Drosophila melanogaster TBI model that reproduces key aspects of TBI in humans, we previously found that the diet consumed immediately following a primary brain injury has a substantial effect on the incidence of mortality within 24 h (early mortality). Flies that receive equivalent primary injuries have a higher incidence of early mortality when fed high-carbohydrate diets versus water. Here, we report that flies fed high-fat ketogenic diet (KD) following TBI exhibited early mortality that was equivalent to that of flies fed water and that flies protected from early mortality by KD continued to show survival benefits weeks later. KD also has beneficial effects in mammalian TBI models, indicating that the mechanism of action of KD is evolutionarily conserved. To probe the mechanism, we examined the effect of KD in flies mutant for Eip75B, an ortholog of the transcription factor PPARγ (peroxisome proliferator-activated receptor gamma) that contributes to the mechanism of action of KD and has neuroprotective effects in mammalian TBI models. We found that the incidence of early mortality of Eip75B mutant flies was higher when they were fed KD than when they were fed water following TBI. These data indicate that Eip75B/PPARγ is necessary for the beneficial effects of KD following TBI. In summary, this work provides the first evidence that KD activates PPARγ to reduce deleterious outcomes of TBI and it demonstrates the utility of the fly TBI model for dissecting molecular pathways that contribute to heterogeneity in TBI outcomes.

Wolf-Hirschhorn syndrome candidate 1 facilitates alveolar macrophage pyroptosis in sepsis-induced acute lung injury through NEK7-mediated NLRP3 inflammasome activation

Sepsis is a complex clinical syndrome with high incidence and mortality. Acute lung injury (ALI) is a common complication of sepsis. At present, there is no effective therapeutic strategy to treat ALI. The SET domain-containing histone methyltransferase Wolf-Hirschhorn syndrome candidate 1 (WHSC1) regulates cancer progression, while its role in sepsis-induced ALI remains unclear. Thus, this study aimed to study the effect of WHSC1 on sepsis-induced ALI and to explore the potential mechanism of action. In the study, LPS treatment induced lung injury. WHSC1 was highly expressed in LPS-induced ALI. Knockdown of WHSC1 attenuated LPS-induced ALI and pyroptosis in vivo. Besides, knockdown of WHSC1 attenuated LPS-induced alveolar macrophage pyroptosis in vitro. Furthermore, NIMA-related kinase-7 (NEK7) expression could be regulated by WHSC1, and NEK7 bound to NLRP3 in alveolar macrophages. Moreover, WHSC1 regulated alveolar macrophage pyroptosis through modulating NEK7-mediated NLRP3 inflammasome activation. In conclusion, WHSC1 was highly expressed in LPS-induced ALI. WHSC1 facilitated alveolar macrophage pyroptosis in sepsis-induced ALI through NEK7-mediated NLRP3 inflammasome activation. WHSC1 may be a valuable target for the therapy of sepsis-induced ALI.

Polydatin alleviates severe traumatic brain injury induced acute lung injury by inhibiting S100B mediated NETs formation

Severe traumatic brain injury (sTBI)-induced acute lung injury (sTBI-ALI) is regarded as the most common complication of sTBI that is an independent predictor of poor outcomes in patients with sTBI and strongly increases sTBI mortality. Polydatin (PD) has been shown to have a potential therapeutic effect on sTBI-induced neurons injury and sepsis-induced acute lung injury (ALI), therefore, it is reasonable to believe that PD has a protective effect on sTBI-ALI. Here, to clarify the PD protective effect following sTBI-ALI, a rat brain injury model of lateral fluid percussion was established to mimic sTBI. As a result, sTBI induced ALI, and caused an increasing of wet/dry weight ratio and lung vascular permeability, as well as sTBI promoted oxidative stress response in the lung; sTBI caused inflammatory cytokines release, such as IL-6, IL-1β, TNF-α and MCP-1; and sTBI promoted NETs formation, mainly including an increasing expression of MPO, NE and CitH3. Simultaneously, sTBI induced a significant increase in the level of S100B; however, when inhibition of S100B, the expression of MPO, NE and CITH3 were significantly inhibited following sTBI. Inhibition of S100B also promoted lung vascular permeability recovery and alleviated oxidative stress response. Furthermore, PD treatmentreduced the pathological lung damage, promoted lung vascular permeability recovery, alleviated oxidative stress response and inflammatory cytokines release; more importantly, PD inhibited the expression of S100B, and NETs formation in the lung following sTBI. These results indicate that PD alleviates sTBI-ALI by inhibiting S100B mediated NETs formation. Thus, PD may be valuable in sTBI-ALI treatment.

Potential Antioxidative, Anti-inflammatory and Immunomodulatory Effects of Ghrelin, an Endogenous Peptide from the Stomach in SARS-CoV2 Infection

The current COVID-19 pandemic is one of the most devastating events in recent history. The respiratory effects of this disease include acute respiratory distress syndrome, systemic inflammation, cytokine storm, and pulmonary fibrosis. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, is a peptide hormone secreted mainly by the stomach. Interestingly, ghrelin possesses promising antioxidant, anti-and inflammatory effects, making it an attractive agent to reduce the complications of the SARS-CoV-2. In addition, ghrelin exerts a wide range of immunomodulatory and anti-inflammatory effects and can mitigate the uncontrolled cytokine production responsible for acute lung injury by upregulating PPARγ and down-regulating NF-κB expression. Ghrelin has also been reported to enhance Nrf2 expression in inflammatory conditions which led to the suppression of oxidative stress. The current opinion summarizes the evidence for the possible pharmacological benefits of ghrelin in the therapeutic management of SARS-CoV-2 infection.

Cigarette smoke extract induces pyroptosis in human bronchial epithelial cells through the ROS/NLRP3/caspase-1 pathway

AIMS

Pyroptosis and inflammation are involved in the development of chronic obstructive pulmonary disease (COPD). However, the cigarette smoke-mediated mechanism of COPD remains unclear. In this study, we aimed to investigate the role of nucleotide-binding domain-like receptor protein-3 (NLRP3) inflammasome-mediated pyroptosis in the death of human bronchial epithelial (HBE) cells after cigarette smoke extract (CSE) exposure.

MAIN METHODS

The protein level of NLRP3 in lung tissue was measured after cigarette smoke exposure in vivo. In vitro, HBE cells were treated with CSE. Subsequently, the activity of caspase-1, lactate dehydrogenase (LDH) release, release of interleukin (IL)-1β and NLRP3 expression levels were measured. The involvement of reactive oxygen species (ROS) was also explored.

KEY FINDINGS

After exposure to CSE, increased release of LDH, the transcriptional and translational upregulation of NLRP3, the caspase-1 activity levels, and enhanced IL-1β and IL-18 release were observed in 16HBE cells. In addition, NLRP3 was required to activate the caspase-1. Our results suggested that pre-stimulated of 16HBE with a caspase-1 inhibitor, or using NLRP3 siRNA to silence NLRP3 expression, also caused the decrease of IL-1β release and pyroptosis.

SIGNIFICANCES

CSE induced inflammation and contributed to pyroptosis through the ROS/NLRP3/caspase-1 pathway in 16HBE cells. The NLRP3 inflammasome participates in CSE-induced HBE cell damage and pyroptosis, which could provide new insights into COPD.

Inflammatory Caspases Drive Pyroptosis in Acute Lung Injury

Acute lung injury (ALI), a critical respiratory disorder that causes diffuse alveolar injury leads to high mortality rates with no effective treatment. ALI is characterized by varying degrees of ventilation/perfusion mismatch, severe hypoxemia, and poor pulmonary compliance. The diffuse injury to cells is one of most important pathological characteristics of ALI. Pyroptosis is a form of programmed cell death distinguished from apoptosis induced by inflammatory caspases, which can release inflammatory cytokines to clear cells infected by pathogens and promote monocytes to reassemble at the site of injury. And pyroptosis not only promotes inflammation in certain cell types, but also regulates many downstream pathways to perform different functions. There is increasing evidence that pyroptosis and its related inflammatory caspases play an important role in the development of acute lung injury. The main modes of activation of pyroptosis is not consistent among different types of cells in lung tissue. Meanwhile, inhibition of inflammasome, the key to initiating pyroptosis is currently the main way to treat acute lung injury. The review summarizes the relationship among inflammatory caspases, pyroptosis and acute lung injury and provides general directions and strategies to conduct further research.

Ghrelin as an Anti-Sepsis Peptide: Review

Sepsis continues to produce widespread inflammation, illness, and death, prompting intensive research aimed at uncovering causes and therapies. In this article, we focus on ghrelin, an endogenous peptide with promise as a potent anti-inflammatory agent. Ghrelin was discovered, tracked, and isolated from stomach cells based on its ability to stimulate release of growth hormone. It also stimulates appetite and is shown to be anti-inflammatory in a wide range of tissues. The anti-inflammatory effects mediated by ghrelin are a result of both the stimulation of anti-inflammatory processes and an inhibition of pro-inflammatory forces. Anti-inflammatory processes are promoted in a broad range of tissues including the hypothalamus and vagus nerve as well as in a broad range of immune cells. Aged rodents have reduced levels of growth hormone (GH) and diminished immune responses; ghrelin administration boosts GH levels and immune response. The anti-inflammatory functions of ghrelin, well displayed in preclinical animal models of sepsis, are just being charted in patients, with expectations that ghrelin and growth hormone might improve outcomes in patients with sepsis.

Diagnostic Accuracy of Plasma Ghrelin Concentrations in Pediatric Sepsis-Associated Acute Respiratory Distress Syndrome: A Single-Center Cohort Study

Background: Ghrelin is the endogenous ligand of growth hormone secretagogue receptor 1a, which plays a role in regulating immunity and inflammation. The aim of this study is to assess the diagnostic value of plasma ghrelin in sepsis-associated pediatric acute respiratory distress syndrome (PARDS). Methods: We recruited patients who were admitted to the pediatric ICU (PICU) of the Children's Hospital of Chongqing Medical University between January 2019 and January 2020 and met the diagnostic criteria for sepsis. Data on clinical variables, laboratory indicators, plasma ghrelin concentrations, and inflammatory factors were collected and evaluated, and patients were followed up for 28 days. The area under the receiver-operating characteristic curves (AUROC) were determined using logistic regression to calculate and test cut-off values for ghrelin as a diagnostic indicator of sepsis-associated PARDS. The log-rank test was used to compare survival according to ghrelin levels. Main results: Sixty-six PICU patients (30 with ARDS and 36 without ARDS) who met the diagnostic criteria of sepsis were recruited. The ghrelin level was significantly higher in the ARDS group than in the non-ARDS group. The AUROC of ghrelin was 0.708 (95% confidence interval: 0.584-0.833) and the positivity cutoff value was 445 pg/mL. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of plasma ghrelin for the diagnosis of PARDS-associated sepsis were 86.7, 50.0, 59.1, 81.8, 1.734, and 0.266%, respectively. The survival rate of sepsis patients were significantly improved when the ghrelin level was >445 pg/mL. Conclusions: Ghrelin plasma levels were higher in sepsis-associated PARDS, and accompanied by increased levels of inflammatory factors. High ghrelin levels are a positive predictor of ICU survival in sepsis patients. Yet, there is no evidence to prove that elevated ghrelin is a promising diagnostic indicator of sepsis-associated PARDS. Trial registration: Clinicaltrials, ChiCTR1900023254. Registered 1 December 2018 - Retrospectively registered, http://www.clinicaltrials.gov/ChiCTR1900023254.

Survival Following Traumatic Brain Injury in Drosophila Is Increased by Heterozygosity for a Mutation of the NF-κB Innate Immune Response Transcription Factor Relish

Traumatic brain injury (TBI) pathologies are caused by primary and secondary injuries. Primary injuries result from physical damage to the brain, and secondary injuries arise from cellular responses to primary injuries. A characteristic cellular response is sustained activation of inflammatory pathways commonly mediated by nuclear factor-κB (NF-κB) transcription factors. Using a Drosophila melanogaster TBI model, we previously found that the main proximal transcriptional response to primary injuries is triggered by activation of Toll and Imd innate immune response pathways that engage NF-κB factors Dif and Relish (Rel), respectively. Here, we found by mass spectrometry that Rel protein level increased in fly heads at 4-8 hr after TBI. To investigate the necessity of Rel for secondary injuries, we generated a null allele, Reldel , by CRISPR/Cas9 editing. When heterozygous but not homozygous, the Reldel mutation reduced mortality at 24 hr after TBI and increased the lifespan of injured flies. Additionally, the effect of heterozygosity for Reldel on mortality was modulated by genetic background and diet. To identify genes that facilitate effects of Reldel on TBI outcomes, we compared genome-wide mRNA expression profiles of uninjured and injured +/+, +/Reldel , and Reldel /Reldel flies at 4 hr following TBI. Only a few genes changed expression more than twofold in +/Reldel flies relative to +/+ and Reldel /Reldel flies, and they were not canonical innate immune response genes. Therefore, Rel is necessary for TBI-induced secondary injuries but in complex ways involving Rel gene dose, genetic background, diet, and possibly small changes in expression of innate immune response genes.

Ethanol Intoxication Alleviates the Inflammatory Response of Remote Organs to Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) may cause damage to distant organs. Acute ethanol intoxication (EI) induces complex local and systemic anti-inflammatory effects and influences the early outcomes of traumatized patients. Here, we evaluated its effects on the BI-induced expression of local inflammatory mediators in the trauma-remote organs the lungs and liver. Male mice were exposed to ethanol as a single oral dose (5g·kg^–1, 32%) before inducing a moderate blunt TBI. Sham groups underwent the same procedures without TBI. Ether 3 or 6h after the TBI, the lung and liver were collected. The gene expression of HMGB1, IL-6, MMP9, IL-1β, and TNF as well as the homogenate protein levels of receptor for advanced glycation end products (RAGE), IL-6, IL-1β, and IL-10 were analyzed. Liver samples were immunohistologically stained for HMGB1. EI decreased the gene expressions of the proinflammatory markers HMGB1, IL-6, and MMP9 in the liver upon TBI. In line with the reduced gene expression, the TBI-induced protein expression of IL-6 in liver tissue homogenates was significantly reduced by EI at 3h after TBI. While the histological HMGB1 expression was enhanced by TBI, the RAGE protein expression in the liver tissue homogenates was diminished after TBI. EI reduced the histological HMGB1 expression and enhanced the hepatic RAGE protein expression at 6h post TBI. With regard to the lungs, EI significantly reduced the gene expressions of HMGB1, IL-6, IL-1β, and TNF upon TBI, without significantly affecting the protein expression levels of inflammatory markers (RAGE, IL-6, IL-1β, and IL-10). At the early stage of TBI-induced inflammation, the gene expression of inflammatory mediators in both the lungs and liver is susceptible to ethanol-induced remote effects. Taken together, EI may alleviate the TBI-induced pro-inflammatory response in the trauma-distant organs, the lungs and liver, via the HMGB1-RAGE axis.