Boswellic acid and apigenin alleviate methotrexate-provoked renal and hippocampal alterations in rats: Targeting autophagy, NOD-2/NF-κB/NLRP3, and connexin-43

The neuronal and renal deteriorations observed in patients exposed to methotrexate (MTX) therapy highlight the need for medical interventions to counteract these complications. Boswellic acid (BA) and apigenin (APG) are natural phytochemicals with prominent neuronal and renal protective impacts in various ailments. However, their impacts on MTX-provoked renal and hippocampal toxicity have not been reported. Thus, the present work is tailored to clarify the ability of BA and APG to counteract MTX-provoked hippocampal and renal toxicity. BA (250 mg/kg) or APG (20 mg/kg) were administered orally in rats once a day for 10 days, while MTX (20 mg/kg, i.p.) was administered once on the sixth day of the study. At the histopathological level, BA and APG attenuated MTX-provoked renal and hippocampal aberrations. They also inhibited astrocyte activation, as proven by the inhibition of glial fibrillary acidic protein (GFAP). These impacts were partially mediated via the activation of autophagy flux, as proven by the increased expression of beclin1, LC3-II, and the curbing of p62 protein, alongside the regulation of the p-AMPK/mTOR nexus. In addition, BA and APG displayed anti-inflammatory features as verified by the damping of NOD-2 and p-NF-κB p65 to reduce TNF-α, IL-6, and NLRP3/IL-1β cue. These promising effects were accompanied with a notable reduction in one of the gap junction proteins, connexin-43 (Conx-43). These positive impacts endorse BA and APG as adjuvant modulators to control MTX-driven hippocampal and nephrotoxicity.

Immunomodulatory poly(L-lactic acid) nanofibrous membranes promote diabetic wound healing by inhibiting inflammation, oxidation and bacterial infection

Background

Given the significant impact on human health, it is imperative to develop novel treatment approaches for diabetic wounds, which are prevalent and serious complications of diabetes. The diabetic wound microenvironment has a high level of reactive oxygen species (ROS) and an imbalance between proinflammatory and anti-inflammatory cells/factors, which hamper the healing of chronic wounds. This study aimed to develop poly(L-lactic acid) (PLLA) nanofibrous membranes incorporating curcumin and silver nanoparticles (AgNPs), defined as PLLA/C/Ag, for diabetic wound healing.

Methods

PLLA/C/Ag were fabricated via an air-jet spinning approach. The membranes underwent preparation and characterization through various techniques including Fourier-transform infrared spectroscopy, measurement of water contact angle, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, assessment of in vitro release of curcumin and Ag+, testing of mechanical strength, flexibility, water absorption and biodegradability. In addition, the antioxidant, antibacterial and anti-inflammatory properties of the membranes were evaluated in vitro, and the ability of the membranes to heal wounds was tested in vivo using diabetic mice.

Results

Loose hydrophilic nanofibrous membranes with uniform fibre sizes were prepared through air-jet spinning. The membranes enabled the efficient and sustained release of curcumin. More importantly, antibacterial AgNPs were successfully reduced in situ from AgNO3. The incorporation of AgNPs endowed the membrane with superior antibacterial activity, and the bioactivities of curcumin and the AgNPs gave the membrane efficient ROS scavenging and immunomodulatory effects, which protected cells from oxidative damage and reduced inflammation. Further results from animal studies indicated that the PLLA/C/Ag membranes had the most efficient wound healing properties, which were achieved by stimulating angiogenesis and collagen deposition and inhibiting inflammation.

Conclusions

In this research, we successfully fabricated PLLA/C/Ag membranes that possess properties of antioxidants, antibacterial agents and anti-inflammatory agents, which can aid in the process of wound healing. Modulating wound inflammation, these new PLLA/C/Ag membranes serve as a novel dressing to enhance the healing of diabetic wounds.

Cinnamaldehyde inhibits the NLRP3 inflammasome by preserving mitochondrial integrity and augmenting autophagy in Shigella sonnei-infected macrophages

BACKGROUND

Worldwide, more than 125 million people are infected with Shigella each year and develop shigellosis. In our previous study, we provided evidence that Shigella sonnei infection triggers activation of the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome in macrophages. NLRP3 inflammasome is responsible for regulating the release of the proinflammatory cytokines interleukin (IL)-1β and IL-18 through the protease caspase-1. Researchers and biotech companies have shown great interest in developing inhibitors of the NLRP3 inflammasome, recognizing it as a promising therapeutic target for several diseases. The leaves of Cinnamomum osmophloeum kaneh, an indigenous tree species in Taiwan, are rich in cinnamaldehyde (CA), a compound present in significant amounts. Our aim is to investigate how CA affects the activation of the NLRP3 inflammasome in S. sonnei-infected macrophages.

METHODS

Macrophages were infected with S. sonnei, with or without CA. ELISA and Western blotting were employed to detect protein expression or phosphorylation levels. Flow cytometry was utilized to assess H2O2 production and mitochondrial damage. Fluorescent microscopy was used to detect cathepsin B activity and mitochondrial ROS production. Additionally, colony-forming units were employed to measure macrophage phagocytosis and bactericidal activity.

RESULTS

CA inhibited the NLRP3 inflammasome in S. sonnei-infected macrophages by suppressing caspase-1 activation and reducing IL-1β and IL-18 expression. CA also inhibited pyroptosis by decreasing caspase-11 and Gasdermin D activation. Mechanistically, CA reduced lysosomal damage and enhanced autophagy, while leaving mitochondrial damage, mitogen-activated protein kinase phosphorylation, and NF-κB activation unaffected. Furthermore, CA significantly boosted phagocytosis and the bactericidal activity of macrophages against S. sonnei, while reducing secretion of IL-6 and tumour necrosis factor following infection.

CONCLUSION

CA shows promise as a nutraceutical for mitigating S. sonnei infection by diminishing inflammation and enhancing phagocytosis and the bactericidal activity of macrophages against S. sonnei.

PANoptosis and Autophagy-Related Molecular Signature and Immune Landscape in Ulcerative Colitis: Integrated Analysis and Experimental Validation

Background

Ulcerative colitis (UC) is an autoimmune inflammatory disorder of the gastrointestinal tract. Programmed cell death (PCD), including PANoptosis and autophagy, plays roles in inflammation and immunity. This study aimed to investigate the molecular signature and immune landscape of the PANoptosis- and autophagy-related differentially expressed genes (DEGs) in UC.

Methods

Analyzing UC dataset GSE206285 yielded DEGs. Differentially expressed PANoptosis- and autophagy-related genes were identified using DEGs and relevant gene collections. Functional and pathway enrichment analyses were conducted. A protein-protein interaction (PPI) network was established to identify hub genes. TRRUST database predicted transcription factors (TFs), pivotal miRNAs, and drugs interacting with hub genes. Immune infiltration analysis, UC-associated single-cell sequencing data analysis, and construction of a competing endogenous RNA (ceRNA) network for hub genes were conducted. Machine learning identified key candidate genes, evaluated for diagnostic value via receiver operating characteristic (ROC) curves. A UC mice model verified expression of key candidate genes.

Results

Identifying ten PANoptosis-related hub DEGs and four autophagy-related hub DEGs associated them with cell chemotaxis, wound healing and positive MAPK cascade regulation. Immune infiltration analysis revealed increased immunocyte infiltration in UC patients, with hub genes closely linked to various immune cell infiltrations. Machine learning identified five key candidate genes, TIMP1, TIMP2, TIMP3, IL6, and CCL2, with strong diagnostic performance. At the single-cell level, these genes exhibited high expression in inflammatory fibroblasts (IAFs). They showed significant expression differences in the colon mucosa of both UC patients and UC mice model.

Conclusion

This study identified and validated novel molecular signatures associated with PANoptosis and autophagy in UC, potentially influencing immune dysregulation and wound healing, thus opening avenues for future research and therapeutic interventions.

In the Eyes of the Beholder-New Mertk Knockout Mouse and Re-Evaluation of Phagocytosis versus Anti-Inflammatory Functions of MERTK

Greg Lemke's laboratory was one of the pioneers of research into the TAM family of receptor tyrosine kinases (RTKs). Not only was Tyro3 cloned in his laboratory, but his group also extensively studied mice knocked out for individual or various combinations of the TAM RTKs Tyro3, Axl, and Mertk. Here we primarily focus on one of the paralogs-MERTK. We provide a historical perspective on rodent models of loss of Mertk function and their association with retinal degeneration and blindness. We describe later studies employing mouse genetics and the generation of newer knockout models that point out incongruencies with the inference that loss of MERTK-dependent phagocytosis is sufficient for severe, early-onset photoreceptor degeneration in mice. This discussion is meant to raise awareness with regards to the limitations of the original Mertk knockout mouse model generated using 129 derived embryonic stem cells and carrying 129 derived alleles and the role of these alleles in modifying Mertk knockout phenotypes or even displaying Mertk-independent phenotypes. We also suggest molecular approaches that can further Greg Lemke's scintillating legacy of dissecting the molecular functions of MERTK-a protein that has been described to function in phagocytosis as well as in the negative regulation of inflammation.

Induction of Hepatoma Cell Pyroptosis by Endogenous Lipid Geranylgeranoic Acid-A Comparison with Palmitic Acid and Retinoic Acid

Research on retinoid-based cancer prevention, spurred by the effects of vitamin A deficiency on gastric cancer and subsequent clinical studies on digestive tract cancer, unveils novel avenues for chemoprevention. Acyclic retinoids like 4,5-didehydrogeranylgeranoic acid (4,5-didehydroGGA) have emerged as potent agents against hepatocellular carcinoma (HCC), distinct from natural retinoids such as all-trans retinoic acid (ATRA). Mechanistic studies reveal GGA's unique induction of pyroptosis, a rapid cell death pathway, in HCC cells. GGA triggers mitochondrial superoxide hyperproduction and ER stress responses through Toll-like receptor 4 (TLR4) signaling and modulates autophagy, ultimately activating pyroptotic cell death in HCC cells. Unlike ATRA-induced apoptosis, GGA and palmitic acid (PA) induce pyroptosis, underscoring their distinct mechanisms. While all three fatty acids evoke mitochondrial dysfunction and ER stress responses, GGA and PA inhibit autophagy, leading to incomplete autophagic responses and pyroptosis, whereas ATRA promotes autophagic flux. In vivo experiments demonstrate GGA's potential as an anti-oncometabolite, inducing cell death selectively in tumor cells and thus suppressing liver cancer development. This review provides a comprehensive overview of the molecular mechanisms underlying GGA's anti-HCC effects and underscores its promising role in cancer prevention, highlighting its importance in HCC prevention.

Autophagy in neural stem cells and glia for brain health and diseases

Autophagy is a multifaceted cellular process that not only maintains the homeostatic and adaptive responses of the brain but is also dynamically involved in the regulation of neural cell generation, maturation, and survival. Autophagy facilities the utilization of energy and the microenvironment for developing neural stem cells. Autophagy arbitrates structural and functional remodeling during the cell differentiation process. Autophagy also plays an indispensable role in the maintenance of stemness and homeostasis in neural stem cells during essential brain physiology and also in the instigation and progression of diseases. Only recently, studies have begun to shed light on autophagy regulation in glia (microglia, astrocyte, and oligodendrocyte) in the brain. Glial cells have attained relatively less consideration despite their unquestioned influence on various aspects of neural development, synaptic function, brain metabolism, cellular debris clearing, and restoration of damaged or injured tissues. Thus, this review composes pertinent information regarding the involvement of autophagy in neural stem cells and glial regulation and the role of this connexion in normal brain functions, neurodevelopmental disorders, and neurodegenerative diseases. This review will provide insight into establishing a concrete strategic approach for investigating pathological mechanisms and developing therapies for brain diseases.

Targeting autophagy to counteract neuroinflammation: A novel antidepressant strategy

Depression is a common disease that affects physical and mental health and imposes a considerable burden on afflicted individuals and their families worldwide. Depression is associated with a high rate of disability and suicide. It causes a severe decline in productivity and quality of life. Unfortunately, the pathophysiological mechanisms underlying depression have not been fully elucidated, and the risk of its treatment is still presented. Studies have shown that the expression of autophagic markers in the brain and peripheral inflammatory mediators are dysregulated in depression. Autophagy-related genes regulate the level of autophagy and change the inflammatory response in depression. Depression is related to several aspects of immunity. The regulation of the immune system and inflammation by autophagy may lead to the development or deterioration of mental disorders. This review highlights the role of autophagy and neuroinflammation in the pathophysiology of depression, sumaries the autophagy-targeting small moleculars, and discusses a novel therapeutic strategy based on anti-inflammatory mechanisms that target autophagy to treat the disease.

Fucoidan alleviated dextran sulfate sodium-induced ulcerative colitis with improved intestinal barrier, reshaped gut microbiota composition, and promoted autophagy in male C57BL/6 mice

Although previous research has unveiled the remedial effects of fucoidan, an extract from marine algae, on ulcerative colitis (UC), the precise mechanisms remain elusive. Animal studies have suggested a connection between autophagy and the beneficial influences of fucoidan intervention. We hypothesized that fucoidan's alleviative effects on dextran sulfate sodium (DSS)-induced UC could be ascribed to autophagy. For our study, we chose 36 male C57BL/6 mice and administered 100 or 400 mg/(kg/body weight/day) of fucoidan via gavage for 5 consecutive weeks. During the last week, the mice were given 3% DSS in drinking water to induce UC. In contrast to the DSS-induced UC model, fucoidan intervention prevented DSS-induced body weight loss, mitigated colon shortening, improved colon mucosa damage, enhanced the intestinal barrier, and reduced serum inflammatory factor concentrations. Furthermore, fucoidan intervention reshaped the gut microbiota compositions, increased the relative abundance of Bacteroidota, Muribaculaceae_unclassified, Clostridiales_unclassified, and Lachnospiraceae_NK4A136_group, and decreased the relative abundance of Firmicutes, Proteobacteria, and Escherichia-Shigella, which led to a lower Firmicutes/Bacteroidota ratio. Additionally, fucoidan treatment enhanced autophagy, as evidenced by upregulated protein expressions of BECLIN1, ATG5, ATG7, and an increased microtubule-associated-proteinlight-chain-3-II/microtubule-associated-proteinlight-chain-3-I ratio. Our findings corroborated the ameliorating effects of fucoidan intervention on DSS-induced UC through autophagy activation, reorganization of gut microbiota, and fortification of the intestinal barrier. This lends support to the therapeutic potential of fucoidan as a natural bioactive ingredient for future UC treatments in humans.

Role of Autophagy and Pyroptosis in Intervertebral Disc Degeneration

Intervertebral disc degeneration is a chronic degenerative disease caused by the interaction of genetic and environmental factors, mainly manifested as lower back pain. At present, the diagnosis of intervertebral disc degeneration mainly relies on imaging. However, early intervertebral disc degeneration is usually insidious, and there is currently a lack of relevant clinical biomarkers that can reliably reflect early disease progression. Pyroptosis is a regulatory form of cell death triggered by the activation of inflammatory bodies and caspase, which can induce the formation of plasma membrane pores and cell swelling or lysis. Previous studies have shown that during the progression of intervertebral disc degeneration, sustained activation of inflammasomes leads to nuclear cell pyroptosis, which can occur in the early stages of intervertebral disc degeneration. Moreover, intervertebral disc nucleus pulposus cells adapt to the external environment through autophagy and maintain cellular homeostasis and studying the mechanism of autophagy in IDD and intervening in its pathological and physiological processes can provide new ideas for the clinical treatment of IDD. This review analyzes the effects of pyroptosis and autophagy on IDD by reviewing relevant literature in recent years, in order to explore the relationship between pyroptosis, autophagy and IDD.

Protective Effects of Sitagliptin on Streptozotocin-Induced Hepatic Injury in Diabetic Rats: A Possible Mechanisms

Diabetes is a ubiquitous disease that causes several complications. It is associated with insulin resistance, which affects the metabolism of proteins, carbohydrates, and fats and triggers liver diseases such as fatty liver disease, steatohepatitis, fibrosis, and cirrhosis. Despite the effectiveness of Sitagliptin (ST) as an antidiabetic drug, its role in diabetes-induced liver injury is yet to be fully investigated. Therefore, this study aims to investigate the effect of ST on hepatic oxidative injury, inflammation, apoptosis, and the mTOR/NF-κB/NLRP3 signaling pathway in streptozotocin (STZ)-induced liver injury. Rats were allocated into four groups: two nondiabetic groups, control rats and ST rats (100 mg/kg), and two diabetic groups induced by STZ, and they received either normal saline or ST for 90 days. Diabetic rats showed significant hyperglycemia, hyperlipidemia, and elevation in liver enzymes. After STZ induction, the results revealed remarkable increases in hepatic oxidative stress, inflammation, and hepatocyte degeneration. In addition, STZ upregulated the immunoreactivity of NF-κB/p65, NLRP3, and mTOR but downregulated IKB-α in liver tissue. The use of ST mitigated metabolic and hepatic changes induced by STZ; it also reduced oxidative stress, inflammation, and hepatocyte degeneration. The normal expression of NF-κB/p65, NLRP3, mTOR, and IKB-α were restored with ST treatment. Based on that, our study revealed for the first time the hepatoprotective effect of ST that is mediated by controlling inflammation, oxidative stress, and mTOR/NF-κB/NLRP3 signaling.

Autophagy facilitates intracellular survival of pathogenic rickettsiae in macrophages via evasion of autophagosomal maturation and reduction of microbicidal pro-inflammatory IL-1 cytokine responses

IMPORTANCE

Rickettsia spp. are intracellular bacterial parasites of a wide range of arthropod and vertebrate hosts. Some rickettsiae are responsible for several severe human diseases globally. One interesting feature of these pathogens is their ability to exploit host cytosolic defense responses to their benefits. However, the precise mechanism by which pathogenic Rickettsia spp. elude host defense responses remains unclear. Here, we observed that pathogenic Rickettsia typhi and Rickettsia rickettsii (Sheila Smith [SS]), but not non-pathogenic Rickettsia montanensis, become ubiquitinated and induce autophagy upon entry into macrophages. Moreover, unlike R. montanensis, R. typhi and R. rickettsii (SS) colocalized with LC3B but not with Lamp2 upon host cell entry. Finally, we observed that both R. typhi and R. rickettsii (SS), but not R. montanensis, reduce pro-inflammatory interleukin-1 (IL-1) responses, likely via an autophagy-mediated mechanism. In summary, we identified a previously unappreciated pathway by which both pathogenic R. typhi and R. rickettsii (SS) become ubiquitinated, induce autophagy, avoid autolysosomal destruction, and reduce microbicidal IL-1 cytokine responses to establish an intracytosolic niche in macrophages.

Randomized, double-blind, placebo-controlled trial of rapamycin in amyotrophic lateral sclerosis

In preclinical studies rapamycin was found to target neuroinflammation, by expanding regulatory T cells, and affecting autophagy, two pillars of amyotrophic lateral sclerosis (ALS) pathogenesis. Herein we report a multicenter, randomized, double-blind trial, in 63 ALS patients who were randomly assigned in a 1:1:1 ratio to receive rapamycin 2 mg/m2/day,1 mg/m2/day or placebo (EUDRACT 2016-002399-28; NCT03359538). The primary outcome, the number of patients exhibiting an increase >30% in regulatory T cells from baseline to treatment end, was not attained. Secondary outcomes were changes from baseline of T, B, NK cell subpopulations, inflammasome mRNA expression and activation status, S6-ribosomal protein phosphorylation, neurofilaments; clinical outcome measures of disease progression; survival; safety and quality of life. Of the secondary outcomes, rapamycin decreased mRNA relative expression of the pro-inflammatory cytokine IL-18, reduced plasmatic IL-18 protein, and increased the percentage of classical monocytes and memory switched B cells, although no corrections were applied for multiple tests. In conclusion, we show that rapamycin treatment is well tolerated and provides reassuring safety findings in ALS patients, but further trials are necessary to understand the biological and clinical effects of this drug in ALS.

Ocular Surface Allostasis-When Homeostasis Is Lost: Challenging Coping Potential, Stress Tolerance, and Resilience

The loss of ocular surface (OS) homeostasis characterizes the onset of dry eye disease. Resilience defines the ability to withstand this threat, reflecting the ability of the ocular surface to cope with and bounce back after challenging events. The coping capacity of the OS defines the ability to successfully manage cellular stress. Cellular stress, which is central to the outcome of the pathophysiology of dry eye disease, is characterized by intensity, continuity, and receptivity, which lead to the loss of homeostasis, resulting in a phase of autocatalytic dysregulation, an event that is not well-defined. To better define this event, here, we present a model providing a potential approach when homeostasis is challenged and the coping capacities have reached their limits, resulting in the stage of heterostasis, in which the dysregulated cellular stress mechanisms take over, leading to dry eye disease. The main feature of the proposed model is the concept that, prior to the initiation of the events leading to cellular stress, there is a period of intense activation of all available coping mechanisms preventing the imminent dysregulation of ocular surface homeostasis. When the remaining coping mechanisms and resilience potential have been maximally exploited and have, finally, been exceeded, there will be a transition to manifest disease with all the well-known signs and symptoms, with a shift to allostasis, reflecting the establishment of another state of balance. The intention of this review was to show that it is possibly the phase of heterostasis preceding the establishment of allostasis that offers a better chance for therapeutic intervention and optimized recovery. Once allostasis has been established, as a new steady-state of balance at a higher level of constant cell stress and inflammation, treatment may be far more difficult, and the potential for reversal is drastically decreased. Homeostasis, once lost, can possibly not be fully recovered. The processes established during heterostasis and allostasis require different approaches and treatments for their control, indicating that the current treatment options for homeostasis need to be adapted to a more-demanding situation. The loss of homeostasis necessarily implies the establishment of a new balance; here, we refer to such a state as allostasis.

Roles of pyroptosis in intervertebral disc degeneration

Intervertebral disc degeneration (IDD), the key pathological process in low back pain, is characterized by chronic inflammation and progressive cell death. Pyroptosis is a type of pro-inflammatory programmed necrosis mediated by inflammasomes that is dependent on the gasdermin family of proteins. An in-depth study of the pathological mechanisms of IDD has revealed that pyroptosis plays an important role in its occurrence and development. The molecular characteristics and activation signaling mechanisms of pyroptosis are reviewed in this paper. Moreover, the specific roles of pyroptosis in IDD pathology are outlined and various targeted drugs for its treatment are highlighted.

Vitamin A Promotes the Fusion of Autophagolysosomes and Prevents Excessive Inflammasome Activation in Dextran Sulfate Sodium-Induced Colitis

Vitamin A ensures intestinal homeostasis, impacting acquired immunity and epithelial barrier function; however, its role in innate immunity is mostly unknown. Here, we studied the impact of vitamin A in different dextran sulfate sodium (DSS)-induced colitis animal models. Interestingly, more severe DSS-induced colitis was observed in vitamin A-deficient (VAD) mice than in vitamin A-sufficient (VAS) mice; the same was observed in VAD severe combined immunodeficient mice lacking T/B cells. Remarkably, IL-1β production, LC3B-II expression, and inflammasome activity in the lamina propria were significantly elevated in VAD mice. Electron microscopy revealed numerous swollen mitochondria with severely disrupted cristae. In vitro, non-canonical inflammasome signaling-induced pyroptosis, LC3B-II and p62 expression, and mitochondrial superoxide levels were increased in murine macrophages (RAW 264.7) pretreated with retinoic acid receptor antagonist (Ro41-5253). These findings suggest that vitamin A plays a crucial role in the efficient fusion of autophagosomes with lysosomes in colitis.

CDK5RAP3, a key defender of udder, modulates NLRP3 inflammasome activation by regulating autophagolysosome degradation in S. agalactiae-infected mastitis

Streptococcus agalactiae, as one of the main pathogens of clinical and subclinical mastitis, affects animal welfare and leads to huge economic losses to farms due to the sharp decline in milk yield. However, both the real pathogenic mechanisms of S. agalactiae-induced mastitis and the regulator which controls the inflammation and autophagy are largely unknown. Served as a substrate of ubiquitin-like proteins of E3 ligase, CDK5RAP3 is widely involved in the regulation of multiple signaling pathways. Our findings revealed that CDK5RAP3 was significantly down-regulated in mastitis infected by S. agalactiae. Surprisingly, inflammasome activation was triggered by CDK5RAP3 knockdown: up-regulated NLRP3, IL1β and IL6, and cleaved caspase1 promoting by NF-κB, thereby resulting in pyroptosis. Additionally, the accumulation of autophagy markers (LC3B and p62) after CDK5RAP3 knockdown suggested that the autophagolysosome degradation pathway was inhibited, thereby activating the NF-κB pathway and NLRP3 inflammasome. Hence, our findings suggest that downregulation or ablation of CDK5RAP3 inhibits autophagolysosome degradation, causes inflammation by activating the NF-κB /NLRP3 inflammasome, and triggers cell death. In conclusion, CDK5RAP3 holds the key to understanding the interaction between autophagy and immune responses, its anti-inflammatory role in this study will throw new light on the clinical drug discovery to cure S. agalactiae mastitis.

Autophagy in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of visual impairment in the aging population with limited understanding of its pathogenesis and a lack of effective treatment. The progression of AMD is initially characterized by atrophic alterations in the retinal pigment epithelium, as well as the formation of lysosomal lipofuscin and extracellular drusen deposits. Damage caused by chronic oxidative stress, protein aggregation and inflammatory processes may lead to geographic atrophy and/or choroidal neovascularization and fibrosis. The role of macroautophagy/autophagy in AMD pathology is steadily emerging. This review describes selective and secretory autophagy and their role in drusen biogenesis, senescence-associated secretory phenotype, inflammation and epithelial-mesenchymal transition in the pathogenesis of AMD.Abbreviations: Aβ: amyloid-beta; AMBRA1: autophagy and beclin 1 regulator 1; AMD: age-related macular degeneration; ATF6: activating transcription factor 6; ATG: autophagy related; BACE1: beta-secretase 1; BHLHE40: basic helix-loop-helix family member e40; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3 like; C: complement; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CARD: caspase recruitment domain; CDKN2A/p16: cyclin dependent kinase inhibitor 2A; CFB: complement factor B; DELEC1/Dec1; deleted in esophageal cancer 1; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; EMT: epithelial-mesenchymal transition; ER: endoplasmic reticulum; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; FUNDC1: FUN14 domain containing 1; GABARAP: GABA type A receptor-associated protein; HMGB1: high mobility group box 1; IL: interleukin; KEAP1: kelch like ECH associated protein 1; LAP: LC3-associated phagocytosis; LAMP2: lysosomal associated membrane protein 2; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NFE2L2: NFE2 like bZIP transcription factor 2; NLRP3; NLR family pyrin domain containing 3; NFKB/NFκB: nuclear factor kappa B; OPTN: optineurin; PARL: presenilin associated rhomboid like; PGAM5: PGAM family member 5, mitochondrial serine/threonine protein phosphatase; PINK1: PTEN induced kinase 1; POS: photoreceptor outer segment; PPARGC1A: PPARG coactivator 1 alpha; PRKN: parkin RBR E3 ubiquitin protein ligase; PYCARD/ASC: PYD and CARD domain containing; ROS: reactive oxygen species; RPE: retinal pigment epithelium; SA: secretory autophagy; SASP: senescence-associated secretory phenotype; SEC22B: SEC22 homolog B, vesicle trafficking protein; SNAP: synaptosome associated protein; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SQSTM1/p62: sequestosome 1; STX: syntaxin; TGFB2: transforming growth factor beta 2; TRIM16: tripartite motif containing 16; TWIST: twist family bHLH transcription factor; Ub: ubiquitin; ULK: unc-51 like autophagy activating kinase; UPR: unfolded protein response; UPS: ubiquitin-proteasome system; V-ATPase: vacuolar-type H+-translocating ATPase; VIM: vimentin.

Research Progress on Autophagy Regulation by Active Ingredients of Traditional Chinese Medicine in the Treatment of Acute Lung Injury

Autophagy is a highly conserved process that maintains cell stability in eukaryotes, participates in the turnover of intracellular substances to maintain cell function, helps to resist pathogen invasion, and improves cell tolerance to environmental changes. Autophagy has been observed in many diseases, and the symptoms of these diseases are significantly improved by regulating autophagy. Autophagy is also involved in the development of lung diseases. Studies have shown that autophagy may play a beneficial or harmful role in acute lung injury (ALI), and ALI has been treated with traditional Chinese medicine designed to promote or inhibit autophagy. In this paper, the molecular mechanism and common pathways regulating autophagy and the relationship between autophagy and ALI are introduced, and the active ingredients of traditional Chinese medicine that improve ALI symptoms by regulating autophagy are summarized.

Autophagy-Modulated Biomaterial: A Robust Weapon for Modulating the Wound Environment to Promote Skin Wound Healing

Autophagy, a self-renewal mechanism, can help to maintain the stability of the intracellular environment of organisms. Autophagy can also regulate several cellular functions and is strongly related to the onset and progression of several diseases. Wound healing is a biological process that is coregulated by different types of cells. However, it is troublesome owing to prolonged treatment duration and poor recovery. In recent years, biomaterials have been reported to influence the skin wound healing process by finely regulating autophagy. Biomaterials that regulate autophagy in various cells involved in skin wound healing to regulate the differentiation, proliferation and migration of cells, inflammatory responses, oxidative stress and formation of the extracellular matrix (ECM) have emerged as a key method for improving the tissue regeneration ability of biomaterials. During the inflammatory phase, autophagy enhances the clearance of pathogens from the wound site and leads to macrophage polarization from the M1 to the M2 phenotype, thus preventing enhanced inflammation that can lead to further tissue damage. Autophagy plays important roles in facilitating the formation of extracellular matrix (ECM) during the proliferative phase, removing excess intracellular ROS, and promoting the proliferation and differentiation of endothelial cells, fibroblasts, and keratinocytes. This review summarizes the close association between autophagy and skin wound healing and discusses the role of biomaterial-based autophagy in tissue regeneration. The applications of recent biomaterials designed to target autophagy are highlighted, including polymeric materials, cellular materials, metal nanomaterials, and carbon-based materials. A better understanding of biomaterial-regulated autophagy and skin regeneration and the underlying molecular mechanisms may open new possibilities for promoting skin regeneration. Moreover, this can lay the foundation for the development of more effective therapeutic approaches and novel biomaterials for clinical applications.

The Role of NLRP3 Inflammasome in IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide today. The NLRP3 inflammasome is a polyprotein complex and an important participant in inflammation. Accumulating studies have shown that the NLRP3 inflammasome participates in a variety of kidney diseases, including IgAN. This review focuses on the role of the NLRP3 inflammasome in IgAN and summarizes multiple involved pathways, which may provide novel treatments for IgAN treatment.

High p62 expression suppresses the NLRP1 inflammasome and increases stress resistance in cutaneous SCC cells

NLRP1 is the primary inflammasome sensor in human keratinocytes. Sensing of UVB radiation by NLRP1 is believed to underlie the induction of sunburn. Although constitutive NLRP1 activation causes skin inflammation and predisposes patients to the development of cutaneous SCCs, the NLRP1 pathway is suppressed in established SCCs. Here, we identified high levels of the autophagy receptor p62 in SCC cells lines and SCC tumors. Increased NF-κB activity in SCC cells causes p62 up-regulation. Suppression of p62 expression rescues UVB-induced NLRP1 inflammasome activation in early-stage SCC cells. p62 expression protects SCC cells from cytotoxic drugs, whereas NLRP1 sensitizes them. In summary, we identify p62 as a novel negative regulator of the NLRP1 inflammasome in human cutaneous SCC cells, in which suppression of NLRP1 by increased levels of p62 supports stress resistance of skin cancer cells.

The Crohn Disease-associated ATG16L1T300A polymorphism regulates inflammatory responses by modulating TLR- and NLR-mediated signaling

The mechanisms by which the ATG16L1^T300A polymorphism affects cell function and causes an increased risk for the development of Crohn disease remain incompletely understood. Here we report that healthy individuals and mice bearing this polymorphism, even as heterozygotes, manifest enhanced TLR, and NLR cytokine and chemokine responses due to increased activation of NFKB. We elucidated the mechanism of the NFKB abnormality and found that in the ATG16L1^T300A cell, there is enhanced polyubiquitination of TRAF6 or RIPK2 resulting from the accumulation of SQSTM1/p62. Indeed, knockout of Sqstm1 in autophagy-deficient cells almost completely normalized TRAF6 or RIPK2 polyubiquitination and NFKB activation in these cells. Thus, by identifying that autophagy is a pathway-intrinsic homeostatic mechanism that restricts excessive TLR- or NLR-mediated inflammatory signaling, our findings shed new light on how the ATG16L1^T300A polymorphism sets the stage for the occurrence of Crohn disease.Abbreviations: 3-MA: 3-methyladenine; ATG16L1: autophagy related 16 like 1; ATG7: autophagy related 7; BMDM: bone marrow-derived macrophage; CD: Crohn disease; CXCL: C-X-C motif chemokine ligand; IBD: inflammatory bowel disease; iBMDM: immortalized mouse BMDM; IL1B/IL-1β: interleukin 1 beta; IL6: interleukin 6; KI: knockin; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; LPS: lipopolysaccharide; MDP: muramyl dipeptide; MEF: mouse embryonic fibroblast; NFKB/NF-κB: nuclear factor kappa B; NFKBIA/IKBA: NFKB inhibitor alpha; NLR: NOD-like receptor; NOD: nucleotide-binding oligomerization domain containing; RIPK2: receptor interacting serine/threonine kinase 2; SNP: single nucleotide polymorphism; SQSTM1/p62: sequestosome 1; TLR: toll like receptor; TNF/TNF-α: tumor necrosis factor; TRAF6: TNF receptor associated factor 6; Ub: ubiquitin; WT: wild type.

Neuropeptide Y Promotes Human M2 Macrophage Polarization and Enhances p62/SQSTM1-Dependent Autophagy and NRF2 Activation

Neuropeptide Y (NPY) is an abundantly expressed peptide capable of modulating innate and adaptive immune responses and regulating chemotaxis and cytokine secretion by macrophages. Abnormal regulation of NPY is involved in the development of atherosclerosis. The inflammatory infiltrate within atherosclerotic plaque is characterized by accumulation of macrophages, which are subject to reprogram their phenotypes in response to environmental signals. Macrophage number and phenotype influence plaque fate. Here, we investigated the effect of NPY on the changes in phenotype and functions of human macrophages, from the pro-inflammatory phenotype M1 to the reparative M2, indicative of atherosclerosis regression or stabilization. Human monocytes were differentiated in vitro into macrophages with M-CSF (M0) and polarized towards an M1 phenotype with IFN-γ plus LPS M(IFN-γ/LPS) or M2 with IL-10 (M IL-10) and further challenged with NPY (10-7-10-9 M) for 8-36 h. Cell phenotype and functions were analyzed by immunofluorescence and immunochemical analyses. NPY affected macrophage surface markers and secretome profile expression, thus shifting macrophages toward an M2-like phenotype. NPY also prevented the impairment of endocytosis triggered by the oxysterol 7-keto-cholesterol (7KC) and prevented 7KC-induced foam cell formation by reducing the lipid droplet accumulation in M0 macrophages. NPY-treated M0 macrophages enhanced the autophagosome formation by upregulating the cell content of the autophagy markers LC3-II and p62-SQSTM1, increased activation of the anti-oxidative transcription factor NRF2 (NF-E2-related factor 2), and subsequently induced its target gene HMOX1 that encodes heme oxygenase-1. Our findings indicate that NPY has a cytoprotective effect with respect to the progression of the inflammatory pathway, both enhancing p62/SQSTM1-dependent autophagy and the NRF2-antioxidant signaling pathway in macrophages. NPY signaling may have a crucial role in tissue homeostasis in host inflammatory responses through the regulation of macrophage balance and functions within atherosclerosis.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

Pyroptosis and Intervertebral Disc Degeneration: Mechanistic Insights and Therapeutic Implications

Low back pain (LBP) is a common problem worldwide, resulting in great patient suffering and great challenges for the social health system. Intervertebral disc (IVD) degeneration (IVDD) is widely acknowledged as one of the key causes of LBP. Accumulating evidence suggests that aberrant pyroptosis of IVD cells is involved in the pathogenesis of IVDD progression, however, the comprehensive roles of pyroptosis in IVDD have not been fully established, leaving attempts to treat IVDD with anti-pyroptosis approaches questionable. In this review, we summarize the characteristics of pyroptosis and emphasize the effects of IVD cell pyroptosis on the pathological progression of IVDD, including secretion of cytokines, nucleus pulposus cell apoptosis and autophagy, accelerated extracellular matrix degradation, annulus fibrosus rupture, cartilage endplate calcification, vascularization, sensory and sympathetic fiber neoinnervation, and infiltrating lymphatic vessels. Finally, we discuss several interventions used to treat IVDD by targeting pyroptosis. This review provides novel insights into the crucial role of IVD cell pyroptosis in IVDD pathogenesis, and could be informative for developing novel therapeutic approaches for IVDD and LBP.

The phagosomal solute transporter SLC15A4 promotes inflammasome activity via mTORC1 signaling and autophagy restraint in dendritic cells

Phagocytosis is the necessary first step to sense foreign microbes or particles and enables activation of innate immune pathways such as inflammasomes. However, the molecular mechanisms underlying how phagosomes modulate inflammasome activity are not fully understood. We show that in murine dendritic cells (DCs), the lysosomal histidine/peptide solute carrier transporter SLC15A4, associated with human inflammatory disorders, is recruited to phagosomes and is required for optimal inflammasome activity after infectious or sterile stimuli. Dextran sodium sulfate-treated SLC15A4-deficient mice exhibit decreased colon inflammation, reduced IL-1β production by intestinal DCs, and increased autophagy. Similarly, SLC15A4-deficient DCs infected with Salmonella typhimurium show reduced caspase-1 cleavage and IL-1β production. This correlates with peripheral NLRC4 inflammasome assembly and increased autophagy. Overexpression of constitutively active mTORC1 rescues decreased IL-1β levels and caspase1 cleavage, and restores perinuclear inflammasome positioning. Our findings support that SLC15A4 couples phagocytosis with inflammasome perinuclear assembly and inhibition of autophagy through phagosomal content sensing. Our data also reveal the previously unappreciated importance of mTORC1 signaling pathways to promote and sustain inflammasome activity.

Exosomes, autophagy and ER stress pathways in human diseases: Cross-regulation and therapeutic approaches

Exosomal release pathway and autophagy together maintain homeostasis and survival of cells under stressful conditions. Autophagy is a catabolic process through which cell entities, such as malformed biomacromolecules and damaged organelles, are degraded and recycled via the lysosomal-dependent pathway. Exosomes, a sub-type of extracellular vesicles (EVs) formed by the inward budding of multivesicular bodies (MVBs), are mostly involved in mediating communication between cells. The unfolded protein response (UPR) is an adaptive response that is activated to sustain survival in the cells faced with the endoplasmic reticulum (ER) stress through a complex network that involves protein synthesis, exosomes secretion and autophagy. Disruption of the critical crosstalk between EVs, UPR and autophagy may be implicated in various human diseases, including cancers and neurodegenerative diseases, yet the molecular mechanism(s) behind the coordination of these communication pathways remains obscure. Here, we review the available information on the mechanisms that control autophagy, ER stress and EV pathways, with the view that a better understanding of their crosstalk and balance may improve our knowledge on the pathogenesis and treatment of human diseases, where these pathways are dysregulated.

Extracellular Hsp90α stimulates a unique innate gene profile in microglial cells with simultaneous activation of Nrf2 and protection from oxidative stress

Delivery of exogenous heat shock protein 90α (Hsp90α) and/or its induced expression in neural tissues has been suggested as a potential strategy to combat neurodegenerative disease. However, within a neurodegenerative context, a pro-inflammatory response to extracellular Hsp90α (eHsp90α) could undermine strategies to use it for therapeutic intervention. The aim of this study was to investigate the biological effects of eHsp90α on microglial cells, the primary mediators of inflammatory responses in the brain. Transcriptomic profiling by RNA-seq of primary microglia and the cultured EOC2 microglial cell line treated with eHsp90α showed the chaperone to stimulate activation of innate immune responses in microglia that were characterized by an increase in NF-kB-regulated genes. Further characterization showed this response to be substantially lower in amplitude than the effects of other inflammatory stimuli such as fibrillar amyloid-β (fAβ) or lipopolysaccharide (LPS). Additionally, the toxicity of conditioned media obtained from microglia treated with fAβ was attenuated by addition of eHsp90α. Using a co-culture system of microglia and hippocampal neuronal cell line HT22 cells separated by a chamber insert, the neurotoxicity of medium conditioned by microglia treated with fAβ was reduced when eHsp90α was also added. Mechanistically, eHsp90α was shown to activate Nrf2, a response which attenuated fAβ-induced nitric oxide production. The data thus suggested that eHsp90α protects against fAβ-induced oxidative stress. We also report eHsp90α to induce expression of macrophage receptor with collagenous structure (Marco), which would permit receptor-mediated endocytosis of fAβ.

Research progress on astrocyte autophagy in ischemic stroke

Ischemic stroke is a highly disabling and potentially fatal disease. After ischemic stroke, autophagy plays a key regulatory role as an intracellular catabolic pathway for misfolded proteins and damaged organelles. Mounting evidence indicates that astrocytes are strongly linked to the occurrence and development of cerebral ischemia. In recent years, great progress has been made in the investigation of astrocyte autophagy during ischemic stroke. This article summarizes the roles and potential mechanisms of astrocyte autophagy in ischemic stroke, briefly expounds on the crosstalk of astrocyte autophagy with pathological mechanisms and its potential protective effect on neurons, and reviews astrocytic autophagy-targeted therapeutic methods for cerebral ischemia. The broader aim of the report is to provide new perspectives and strategies for the treatment of cerebral ischemia and a reference for future research on cerebral ischemia.

The Significance of NLRP Inflammasome in Neuropsychiatric Disorders

The NLRP inflammasome is a multi-protein complex which mainly consists of the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain. Its activation is linked to microglial-mediated neuroinflammation and partial neuronal degeneration. Many neuropsychiatric illnesses have increased inflammatory responses as both a primary cause and a defining feature. The NLRP inflammasome inhibition delays the progression and alleviates the deteriorating effects of neuroinflammation on several neuropsychiatric disorders. Evidence on the central effects of the NLRP inflammasome potentially provides the scientific base of a promising drug target for the treatment of neuropsychiatric disorders. This review elucidates the classification, composition, and functions of the NLRP inflammasomes. It also explores the underlying mechanisms of NLRP inflammasome activation and its divergent role in neuropsychiatric disorders, including Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, depression, drug use disorders, and anxiety. Furthermore, we explore the treatment potential of the NLRP inflammasome inhibitors against these disorders.

Interaction Between Autophagy and Porphyromonas gingivalis-Induced Inflammation

Autophagy is an immune homeostasis process induced by multiple intracellular and extracellular signals. Inflammation is a protective response to harmful stimuli such as pathogen microbial infection and body tissue damage. Porphyromonas gingivalis infection elicits both autophagy and inflammation, and dysregulation of autophagy and inflammation promotes pathology. This review focuses on the interaction between autophagy and inflammation caused by Porphyromonas gingivalis infection, aiming to elaborate on the possible mechanism involved in the interaction.

The correlation between the inflammatory effects of activated macrophages in atherosclerosis and aortic dissection

OBJECTIVE

To study the correlation between lipid metabolism index, inflammatory factor index and M1 macrophage content, and aortic dissection.

METHODS

Patients with only basic atherosclerotic diseases were selected as the control group, and patients with only basic atherosclerotic diseases and aortic dissection were set as experiment group. Blood of patients was collected. Chemiluminescent immunoassay was applied to determine the concentration of total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL), apolipoprotein A1 (ApoA1) (ApoA1) and apolipoprotein B1 (ApoB1). ELISA assay was applied to measure the concentration of tumor necrosis factor-α (TNF-α), Interleukin 1β (IL-1β), interleukin-6 (IL-6) and interleukin-10 (IL-10). The content of M1 macrophages in blood was measured with FCM (Flow cytometry) method. The correlation between the inflammatory effects of activated macrophages in atherosclerosis and aortic dissection was analyzed by simple linear regression analysis.

RESULTS

Concentration of TC, TG, LDL-C and ApoB, and the concentration of TNF-α, IL-1β and IL-6 in experiment group were markedly higher compared to those in the control group, while the concentration of HDL-C and ApoA1, and IL-10 concentration in experiment group was markedly lower. The content of M1 macrophage in the control group was significantly lower compared to experiment group. The proportion of M1 macrophages, concentration of TC, TG, LDL, HDL, ApoA1 and ApoB1, and concentration of TNF-α, IL-1β, IL-6 and IL-10 were all significantly correlated to the occurrence of aortic dissection.

CONCLUSION

The proportion of M1 macrophages, concentration of TC, TG, LDL, HDL, ApoA1 and ApoB1, and concentration of TNF-α, IL-1β, IL-6 and IL-10 are significantly correlated with the occurrence of aortic dissection.

Autophagy-Inflammation Interplay During Infection: Balancing Pathogen Clearance and Host Inflammation

Inflammation is an essential immune response of the host against infections but is often over-activated, leading to a variety of disorders. Autophagy, a conserved degradation pathway, also protects cells by capturing intracellular pathogens that enter the cell and transporting them to the lysosome for clearance. Dysfunctional autophagy is often associated with uncontrolled inflammatory responses during infection. In recent years, more and more research has focused on the crosstalk between autophagy and inflammation. In this paper, we review the latest research advances in this field, hoping to gain insight into the mechanisms by which the body balances autophagy and inflammation in infections and how this mechanism can be used to fight infections better.

MAPK p38/Ulk1 pathway inhibits autophagy and induces IL-1β expression in hepatic stellate cells

In the past, hepatic stellate cells (HSCs) were considered to be noninflammatory cells and to contribute to liver fibrosis by producing extracellular matrix. Recently, it was found that HSCs can also secrete cytokines and chemokines and therefore participate in hepatic inflammation. Autophagy participates in many immune response processes in immune cells. It is unclear whether autophagy is involved in inflammatory cytokine induction in HSCs. MAPK p38, Ulk1 phosphorylation, and the Ulk1-Atg13 complex were analyzed in HSC-T6 cells after LPS treatment. The relationship between autophagy inhibition and inflammation was investigated in primary rat HSCs. We discovered that LPS inhibited autophagy through MAPK p38. The activation of MAPK p38 induced Ulk1 phosphorylation, which disrupted the Ulk1-Atg13 complex and therefore inhibited autophagy. Furthermore, in primary rat HSCs, we demonstrated that autophagy inhibition regulated IL-1β induction, which depended on the MAPK p38/Ulk1 pathway. Our results reveal a continuous signaling pathway, MAPK p38-Ulk1 phosphorylation-Ulk1-Atg13 disruption, which inhibits autophagy and induces IL-1β expression in HSCs.NEW & NOTEWORTHY LPS inhibits autophagy in a concentration- and dose-dependent manner in HSC-T6 cells. MAPK p38 induces phosphorylation of Ulk1, which disrupts the Ulk1-Atg13 complex and is therefore required for the inhibition of autophagy by LPS. LPS induces IL-1β expression via the MAPK p38/Ulk1 pathway in HSCs.

3β,23-Dihydroxy-12-ene-28-ursolic Acid Isolated from Cyclocarya paliurus Alleviates NLRP3 Inflammasome-Mediated Gout via PI3K-AKT-mTOR-Dependent Autophagy

Gout is regarded as a painful inflammatory arthritis induced by the deposition of monosodium urate crystals in joints and soft tissues. Nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome-mediated IL-1β production plays a crucial role in the pathological process of gout. Cyclocarya paliurus (CP) tea was found to have an effect on reducing the blood uric acid level of people with hyperuricemia and gout. However, its medicinal ingredients and mechanism for the treatment of gout are still unclear. Thus, this study was designed to investigate the effects of the active triterpenoids isolated from C. paliurus on gout and explore the underlying mechanism. The results showed that compound 2 (3β,23-dihydroxy-12-ene-28-ursolic acid) from C. paliurus significantly decreased the protein expression of IL-1β, caspase-1, pro-IL-1β, pro-caspase-1, and NLRP3. Furthermore, the production of ROS in the intracellular was reduced after compound 2 treatment. However, ROS agonist rotenone remarkably reversed the inhibitory effect of compound 2 on the protein expression of NLRP3 inflammasome. Additionally, the expression level of LC3 and the ratio of LC3II/LC3I were increased, but the expression level of p62 was suppressed by compound 2 whereas an autophagy inhibitor 3-methyladenine (3-MA) significantly abolished the inhibitory effects of compound 2 on the generation of ROS and the protein expression of NLRP3 inflammasome. Moreover, compound 2 could ameliorate the expression ratio of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR. Interestingly, mTOR activator MHY-1485 could block the promotion effect of compound 2 on autophagy regulation and inhibitory effect of compound 2 on induction of ROS and IL-1β. In conclusion, these findings suggested that compound 2 may effectively improve NLRP3 inflammasome-mediated gout via PI3K-AKT-mTOR-dependent autophagy and could be further investigated as a potential agent against gout.

Skin damage induced by zinc oxide nanoparticles combined with UVB is mediated by activating cell pyroptosis via the NLRP3 inflammasome-autophagy-exosomal pathway

BACKGROUND

Zinc oxide nanoparticles (ZnONPs) are widely used nanomaterial in personal cosmetics, such as skin creams and sunscreens, due to their whitening properties and strong UV light absorption. However, the safety issues and the hazards of ZnONPs, which can be taken up by the skin and cause skin toxicity, are still unclear. From a chemoprevention point of view, pterostilbene (PT) has been reported to prevent skin damage effectively by its anti-inflammatory and autophagy inducer effect. This study aims to determine the skin toxicity and the potential mechanisms of UVB and ZnONPs exposure and the preventive effect of PT.

RESULTS

The co-exposure of UVB and ZnONPs elicit NLRP3 inflammasome activation and pyroptosis in keratinocytes. Furthermore, exposure to both UVB and ZnONPs also disrupts cellular autophagy, which increases cell exosome release. In vivo UVB and ZnONPs exposure triggers skin toxicity, as indicated by increased histological injury, skin thickness and transepidermal water loss. Notably, the NLRP3 inflammasome-mediated pyroptosis are also activated during exposure. Topical application of pterostilbene attenuates NLRP3 inflammasome activation and pyroptosis by decreasing ROS generation and mitochondrial ROS (mtROS) levels. In addition to its antioxidant effect, PT also reversed autophagy abnormalities by restoring normal autophagic flux and decreasing NLRP3 inflammasome-loaded exosome release.

CONCLUSIONS

Our findings reveal that ZnONPs induce skin damage in conjunction with UVB exposure. This process involves an interplay of inflammasomes, pyroptosis, autophagy dysfunction, and exosomes in skin toxicity. PT alleviates skin inflammation by regulating the inflammasome-autophagy-exosome pathway, a finding which could prove valuable when further evaluating ZnONPs effects for cosmetic applications.

AMPK-mediated autophagy modulates the inflammatory cytokine expression in intestinal epithelial cells induced by high glucose

Introduction: The homeostasis of intestinal epithelial cells (IECs) is disrupted in diabetes, leading to functional changes of the gastrointestinal tract and increasing the risk of diabetic enteropathy. Methods: The aim of this study is to explore the effect of autophagy on the expression of inflammatory factors under high glucose in vitro. The effect of glucose at different concentrations (5, 10, 30 and 50 Mm) on IEC-6 cells was analyzed. Dorsomorphin (AMPK antagonist) and GSK621 (AMPK agonist) were used to examine the relationship between the autophagy and the AMPK/ULK1 signaling pathway in IEC-6 cells. Results: Our results showed that the high glucose significantly inhibited the growth of IECs, and induced more shrinkage and necrosis of cells. Autophagy was inhibited by high glucose. Furthermore, the levels of cytokines, including IL-22, INF-γ, NOS2, and TNF-α, were significantly increased, which were positively correlated with glucose concentration. Additionally, we confirmed that Dorsomorphin down-regulated the expression of p-AMPK and autophagy protein compared with GSK621. Similar, cellular immunofluorescence also detected low autophagy expression. However, GSK621 and Rapamycin increased the level of autophagy and down-regulated the secretion of pro-inflammatory factors compared with Dorsomorphin. Conclusion: Therefore, our results demonstrate that AMPK mediated autophagy may regulate levels of inflammation in IECs and improve cell survival under high glucose.

Identification of Pharmacological Autophagy Regulators of Active Ulcerative Colitis

Background: Ulcerative colitis (UC) is a chronic recurrent disease of unknown etiology. Recently, it has been reported that autophagy-related gene polymorphism is closely associated with increased risk of UC, and the therapeutic effect of some UC drugs is mediated by regulating autophagy pathways. This study aims to identify pivotal autophagy-related regulators in UC pathogenesis and provide novel molecular targets for the treatment of active UC.

Methods: Gene expression profiles and clinical information of active UC patients were obtained from GEO databases. CIBERSORT was adopted to evaluate the immune cell infiltration. We used weighted gene co-expression network analysis (WGCNA) and differential expression analysis to identify the pivotal modules and genes associated with active UC. Subsequently, we conducted validation in the validation set and explored its relationship with commonly used UC therapeutics.

Results: 36 healthy controls and 46 active UC patients have been obtained from the training set of GSE53306, GSE87466, and GSE134025. There were 423 differentially expressed genes (DEGs) found, which dramatically enriched in autophagy-related pathways. And more infiltration of mast cells, activated T cells, dendritic cells, and M1 macrophages were observed in the intestinal mucosa of active UC, while more infiltration of resting immune cells and M2 macrophages in healthy controls. WGCNA indicated that the turquoise and blue modules were the critical modules. CASP1, SERPINA1, and CCL2 have been identified as the hub autophagy-related genes of active UC, after combining DEGs and 232 autophagy-related genes from HADb with the genes of turquoise and blue modules, respectively. We further verified that CASP1, SERPINA1, and CCL2 were positively associated with active UC and served as an autophagy-related biomarker for active UC. Moreover, increased SERPINA1 in the involved intestinal mucosa was reduced in patients with active UC who responded to golimumab or glucocorticoid therapy. But, neither CASP1, SERPINA1, and CCL2 were changed by treatment of 5-aminosalicylic acid (5-ASA) and azathioprine.

Conclusion: CASP1, SERPINA1, and CCL2 are autophagy-related hub genes of active UC. And SERPINA1 may serve as a new pharmacological autophagy regulator of UC, which provides a new target for the use of small molecules targeting autophagy in the treatment of active UC.

LKB1 Regulates Vascular Macrophage Functions in Atherosclerosis

Liver kinase B1 (LKB1) is known to shape the regulation of macrophage function by participating in multiple processes including cell metabolism, growth, and polarization. However, whether LKB1 also affects the functional plasticity of macrophages in atherosclerosis has not attracted much attention. Abnormal macrophage function is a pathophysiological hallmark of atherosclerosis, characterized by the formation of foam cells and the maintenance of vascular inflammation. Mounting evidence supports that LKB1 plays a vital role in the regulation of macrophage function in atherosclerosis, including affecting lipid metabolism reprogramming, inflammation, endoplasmic reticulum stress, and autophagy in macrophages. Thus, decreased expression of LKB1 in atherosclerosis aggravates vascular injury by inducing excessive lipid deposition in macrophages and the formation of foam cells. To systematically understand the role and potential mechanism of LKB1 in regulating macrophage functions in atherosclerosis, this review summarizes the relevant data in this regard, hoping to provide new ideas for the prevention and treatment of atherosclerosis.

Phagosome maturation and modulation of macrophage effector function by intracellular pathogens: target for therapeutics

Macrophages are important cells that regulate various innate functions. Macrophages after engulfment of pathogens proceed for phagosome maturation and finally fuse with lysosomes to kill pathogens. Although pathogen degradation is one of the important functions of phagosomes, various immune-effector functions of macrophages are also dependent on the phagosome maturation process. This review discusses signaling processes regulating phagosome maturation as well as various effector functions of macrophages such as apoptosis, antigen presentation, autophagy and inflammasome that are dependent on the phagosome maturation process. It also discusses strategies adopted by various intracellular pathogens to counteract these functions to evade intracellular destruction mechanisms. These studies may give direction for the development of new therapeutics to control various intracellular infections.

A rapid increase in lysophospholipids after geranylgeranoic acid treatment in human hepatoma-derived HuH-7 cells revealed by metabolomics analysis

Geranylgeranoic acid (GGA) was developed as a preventative agent against second primary hepatoma, and was reported to induce cell death in human hepatoma cells via Toll-like receptor 4 (TLR4)-mediated pyroptosis. We recently reported that GGA is enzymatically biosynthesized from mevalonic acid in human hepatoma-derived HuH-7 cells and that endogenous GGA is found in most rat organs including the liver. An unbiased metabolomics analysis of ice-cold 50% acetonitrile extracts from control and GGA-treated cells was performed in this study to characterize the intracellular metabolic changes in GGA-induced pyroptosis and to analyze their relationship with the mechanism of GGA-induced cell death. The total positive ion chromatograms of the cellular extracts in ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry were apparently unchanged after GGA treatment, but an orthogonal partial least squares-discriminant analysis score plot clearly discriminated the intracellular metabolite profiles of GGA-treated cells from that of control cells. S-plot analysis revealed 15 potential biomarkers up-regulated by 24-h GGA treatment according to their variable importance in the projection value of more than 1, and the subsequent metabolomics analysis identified nine of these metabolites as a group of lysophospholipids containing lysophosphatidylcholine with C16:0, C20:4, or C20:3 fatty acids. The possible roles of these lysophospholipids in GGA-induced pyroptosis are discussed.

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Metabolomics analysis was performed on geranylgeranoic acid (GGA)-treated cells.

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Total positive ion chromatograms were apparently similar after GGA treatment.

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The OPLS-DA score plot distinguished the GGA-treated cells from control cells.

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The S-plot analysis revealed GGA-induced upregulation of lysophospholipids.

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The possible roles of lysophospholipids in GGA-induced pyroptosis are discussed.

Ratio of serum amyloid A to C-reactive protein is constant in the same patients but differs greatly between patients with inflammatory diseases

C-reactive protein (CRP) is commonly monitored to track the activity of inflammation and has become the gold standard in the management of all inflammatory diseases. Indeed, serum amyloid A (SAA) have seemed to correlate moderately with CRP, but the discrepancy of CRP and SAA levels has often been reported, especially in rheumatoid arthritis. Then, we examined CRP reflects a real magnitude of inflammation in patients with rheumatic and infectious inflammatory diseases. A total of 414 patients with infectious and non-infectious inflammatory diseases were enrolled. At initial visit, each patient underwent a clinical assessment and had also laboratory tests such as SAA and CRP. In each patient, we carried out a longitudinal analysis of CRP and SAA levels. We determined the inter-individual correlation between SAA and CRP and also clarified intra-individual changes of SAA/CRP ratio. SAA and CRP levels changed approximately linearly over time within individuals irrespective of rheumatic and infectious inflammatory diseases. However, SAA/CRP ratios differed dramatically between patients (from 0.117 to 50.8, median 5.71). In patients with high SAA/CRP ratio (>8.44), SAA is a better predictor of inflammation than CRP. In contrast, CRP is a better predictor in patients with low ratio (<3.52). Our results suggest that the SAA/CRP ratio differed greatly between individuals but was constant in intra-individuals. Low CRP levels could be accompanied by SAA levels predicting any degree of inflammation, implying that CRP is not reflecting a real magnitude of inflammation. To evaluate the real magnitude of inflammation, to access the SAA/CRP ratio in advance is essential.

Beclin1 controls caspase-4 inflammsome activation and pyroptosis in mouse myocardial reperfusion-induced microvascular injury

BACKGROUND

Myocardial reperfusion injury is often accompanied by cell death and inflammatory reactions. Recently, pyroptosis is gradually recognized as pivotal role in cardiovascular disease. However, little is known about the regulatory role of beclin1 in the control of caspase-4 activation and pyroptosis. The present study confirmed whether beclin1 regulates caspase-4 mediated pyroptosis and thereby protects Human Cardiac microvascular endothelial cells (HCMECs) against injury.

METHODS

TTC and Evan's blue dye, western blot, immunofluorescence and immunohistochemistry staining were performed in wild mice and transgenic mice with overexpression of beclin 1(BECN1-Tg). CMECs were transfected with a beclin1 lentivirus. The cell cytotoxicity was analyzed by LDH-Cytotoxicity Assay Kit. The protein levels of autophagy protein (Beclin1, p62 and LC3II/LC3I) and caspase-4/GSDMD pathway were determined by western blot. Autophagic vacuoles in cells were monitored with RFP-GFP-LC3 using fluorescence microscope.

RESULTS

I/R caused caspase-4 activity and gasdermin D expression increase in vivo and in vitro. Overexpression of beclin1 in heart tissue and CMECs suppressed the caspase-4 activity and decreased the levels of gasdermin D; meanwhile beclin1 overexpression also reduced IL-1β levels, promoted autophagy (p62 expression was inhibited while LC3II expression was increased) in the heart and CMECs. Interestingly, beclin1 overexpression increased animal survival and attenuated myocardial infarct size (45 ± 6.13 vs 22 ± 4.37), no-reflow area (39 ± 5.22 vs 16 ± 2.54) post-myocardial ischemia reperfusion.

CONCLUSIONS

Induction of beclin-1 signaling can be a potential therapeutic target in myocardial reperfusion-induced microvascular injury. Video Abstract.

Extracellular Hsp90 and protection of neuronal cells through Nrf2

Heat shock protein 90 (Hsp90), although one of the most essential intracellular chaperones, can also play key roles in the extracellular milieu. Here, we review the properties of extracellular Hsp90 in cellular homeostasis in the heat shock response (HSR), focusing on cells of the central nervous system. Hsp90 can be secreted by microglia as well as other cell types by non-canonical pathways of secretion. The chaperone may then influence the behavior of distant cells and can for instance protect neuronal cells from the oxidative burst accompanying phagocytosis by microglia of beta-amyloid fibrils. A mechanism involving activation of the transcription factor Nrf2, and induction of the antioxidant response is reported. We review the potential role of extracellular Hsp90, Nrf2 and transcellular chaperone signaling in the non-cell-intrinsic HSR.

Effects of miRNAs in exosomes derived from α-synuclein overexpressing SH-SY5Y cells on autophagy and inflammation of microglia

Our previous study has revealed that GFP-α-synuclein overexpressing SH-SY5Y cells-derived exosomes (GFP-SNCA Exo) decrease autophagy in microglia via their load of miRNAs. However, it is unclear whether GFP-SNCA Exo can affect microglial inflammation via modulation of autophagy. In order to investigate the effects of miRNAs carried by GFP-SNCA Exo on autophagy and inflammation of microglia. SH-SY5Y cells were transfected with lentivirus expressing α-synuclein and then their exosomes were collected. Western blot and laser confocal images showed that α-synuclein transferred between SH-SY5Y cells and microglia through exosomes. Differentially expressed miRNAs between GFP-SNCA Exo and the vector exosomes were detected by microarray analysis. After bioinformatics analysis of the differentially expressed miRNAs, we found that their target genes were enriched in the MAPK and autophagy-associated signaling pathway. The expression of P62, p-JNK/JNK, and p-ERK/ERK and the release of IL-6 significantly increased whereas LC3 II/I decreased in microglia exposed to GFP-SNCA Exo for 48 h when compared to the control group. But rapamycin could reverse the increasing expression of p-JNK/JNK, p-ERK/ERK and the release of IL-6 induced by GFP-SNCA Exo. Dual immunofluorescence staining for LC3B and LAMP1 showed that the fluorescence density of LC3B decreased and the fluorescence of LC3B and LAMP1 were not co-located in microglia after 48 h co-culture with GFP-SNCA Exo compared with the control group, which indicated that these exosomes decreased autophagy and impaired the autophagy flux in recipient microglia. Taken together, our results indicate that GFP-SNCA Exo activate the MAPK signaling pathway and inflammation by decreasing autophagy in microglia.

Leojaponin inhibits NLRP3 inflammasome activation through restoration of autophagy via upregulating RAPTOR phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCE

Duan Teng Yimu decoction is a Chinese herbal medicine compound with proven therapeutic effects on inflammasome-related diseases, such as rheumatoid arthritis. This decoction consists of three Chinese herbal medicines, including Leonurus japonicus (L. japonicus), which promotes the blood circulation and exhibits detumescence activity, traditionally curing gynecologic and inflammasome diseases.

AIM OF THE STUDY

To explore the anti-inflammasome activity and the underlying mechanisms of action of the compounds from L. japonicus.

MATERIALS AND METHODS

A series of compounds were isolated from L. japonicus. Their anti-inflammasome activities were evaluated in macrophages that were co-stimulated by lipopolysaccharide (LPS) and NLRP3 inflammasome inducers. NLRP3 inflammasome formation and apoptosis speck like containing a CARD (ASC) oligomerization were evaluated by immunofluorescent microscopy and Western blot analysis. The regulation of autophagy after treatment of this compound was also evaluated. Lastly, in vivo activity of Leojaponin was analyzed in a mouse acute gouty arthritis model.

RESULTS

Here we show that Leojaponin, a diterpenoid compound from L. japonicus, suppressed lactate dehydrogenase and IL-1β release in Nigericin-stimulated macrophages in a pyroptosis model. Leojaponin inhibits NLRP3 inflammasome activation in both J774A.1 cells and bone marrow-derived macrophages in a dose dependent manner. Moreover, Leojaponin suppressed NLRP3-mediated ASC specks formation and ASC oligomerization. These activities of Leojaponin depend on restoration of autophagy via promoting RAPTOR phosphorylation. Furthermore, Leojaponin ameliorated monosodium urate (MSU)-induced acute gouty arthritis in vivo.

CONCLUSION

Our findings suggest that Leojaponin inhibits NLRP3 inflammasome activation through enhancing autophagy via RAPTOR phosphorylation, thereby highlighting Leojaponin as a potent drug for inflammasome-related diseases.

Activation of AMPK/mTOR-driven autophagy and inhibition of NLRP3 inflammasome by saxagliptin ameliorate ethanol-induced gastric mucosal damage

AIMS

Saxagliptin, a selective/potent dipeptidyl peptidase-4 inhibitor, has revealed remarkable anti-inflammatory features in murine models of nephrotoxicity, hepatic injury, and neuroinflammation. However, its potential effect on ethanol-induced gastric mucosal injury has not been examined. Hence, the present work investigated the prospect of saxagliptin to attenuate ethanol-evoked gastric injury, with emphasis on the AMPK/mTOR-driven autophagy and NLRP3/ASC/caspase-1 pathway.

MATERIALS AND METHODS

In ethanol-induced gastropathy, the gastric tissues were examined by immunohistochemistry, immunoblotting, histopathology, and ELISA.

KEY FINDINGS

The results demonstrated that saxagliptin (10 mg/kg; by gavage) suppressed the gastric pathological signs (area of gastric ulcer and ulcer index scores), histopathologic aberrations/damage scores, without provoking hypoglycemia in rats. These protective features were attributed to the enhancement of gastric mucosal autophagy flux, as proven with increased expression of LC3-II and Beclin 1, decreased accumulation of p62 SQSTM1, and activation of the autophagy-linked AMPK/mTOR pathway by increasing the expression of p-AMPK/AMPK and decreasing the expression of the autophagy suppressor p-mTOR/mTOR signal. In tandem, saxagliptin counteracted the ethanol-induced pro-apoptotic events by downregulating Bax, upregulating Bcl2 protein, and lowering the Bax/Bcl2 ratio. Equally important, saxagliptin suppressed the NLRP3 inflammasome in the gastric tissue by lowering the expression of NLRP3, ASC, and nuclear NF-κBp65, decreasing the activity of caspase-1, and diminishing the IL-1β levels. In the same regard, saxagliptin suppressed the mucosal oxidative stress by lowering lipid peroxide levels, increasing GSH and GPx antioxidants, and activating Nrf2/HO-1 pathway.

SIGNIFICANCE

Saxagliptin may be a promising intervention against ethanol-evoked gastropathy by activating AMPK/mTOR-driven autophagy and inhibiting NLRP3 inflammasome.

TAX1BP1 protects against myocardial infarction-associated cardiac anomalies through inhibition of inflammasomes in a RNF34/MAVS/NLRP3-dependent manner

Acute myocardial infarction (MI), one of the most common cardiovascular emergencies, is a leading cause of morbidity and mortality. Ample evidence has revealed an essential role for inflammasome activation and autophagy in the pathogenesis of acute MI. Tax1-binding protein 1 (TAX1BP1), an adaptor molecule involved in termination of proinflammatory signaling, serves as an important selective autophagy adaptor, but its role in cardiac ischemia remains elusive. This study examined the role of TAX1BP1 in myocardial ischemic stress and the underlying mechanisms involved. Levels of TAX1BP1 were significantly downregulated in heart tissues of patients with ischemic heart disease and in a left anterior descending (LAD) ligation-induced model of acute MI. Adenovirus carrying TAX1BP1 was delivered into the myocardium. The acute MI induced procedure elicited an infarct and cardiac dysfunction, the effect of which was mitigated by TAX1BP1 overexpression with little effect from viral vector alone. TAX1BP1 nullified acute MI-induced activation of the NLRP3 inflammasome and associated mitochondrial dysfunction. TAX1BP1 overexpression suppressed NLRP3 mitochondrial localization by inhibiting the interaction of NLRP3 with mitochondrial antiviral signaling protein (MAVS). Further investigation revealed that ring finger protein 34 (RNF34) was recruited to interact with TAX1BP1 thereby facilitating autophagic degradation of MAVS through K27-linked polyubiquitination of MAVS. Knockdown of RNF34 using siRNA nullified TAX1BP1 yielded protection against hypoxia-induced MAVS mitochondrial accumulation, NLRP3 inflammasome activation and associated loss of mitochondrial membrane potential. Taken together, our results favor a cardioprotective role for TAX1BP1 in acute MI through repression of inflammasome activation in a RNF34/MAVS-dependent manner.

New insights into crosstalk between pyroptosis and autophagy co-induced by molybdenum and cadmium in duck renal tubular epithelial cells

Pyroptosis and autophagy are two different biological processes that determine cell fates. Our previous studies revealed that pyroptosis and autophagy were involved in cytotoxicity co-induced by molybdenum (Mo) and cadmium (Cd) in duck renal tubular epithelial cells, but crosstalk between them is unclear. Hence, the cells were treated with 500.0 μM Mo, 4.0 μM Cd, 10.0 μM Z-YVAD-fluoromethylketone (YVAD), 2.5 μM 3-methyladenine (3-MA) and 10.0 μM chloroquine (CQ) alone or in combination for 12 h (CQ for the last 4 h). Under Mo and Cd co-stress, data evidenced that YVAD addition decreased the number of autophagosomes, LC3 puncta, and AMPKα-1, Atg5, Beclin-1, LC3A, LC3B mRNA levels and LC3-II/LC3-I, Beclin-1 protein levels, and increased p62 expression levels. Besides, both 3-MA and CQ addition increased NLRP3, Caspase-1, NEK7, ASC, GSDMA, GSDME, IL-1β, IL-18 mRNA levels, NLRP3, Caspase-1 p20, ASC, GSDMD protein and ROS levels, and NO, LDH, IL-1β, IL-18 releases. Collectively, our results revealed that pyroptosis and autophagy co-induced by Mo and Cd were interrelated in duck renal tubular epithelial cells, and inhibiting pyroptosis might attenuate Mo and Cd co-induced autophagy, but inhibiting autophagy might promote Mo and Cd co-induced pyroptosis.