Metformin attenuates lipopolysaccharide-induced epithelial cell senescence by activating autophagy

Acute lung injury (ALI) is a life-threatening medical condition with higher mortality and morbidity in elderly patients. Recently, metformin, a drug commonly used to lower blood glucose in type 2 diabetes patients, has been shown to be an effective anti-inflammatory agent in ALI. However, the mechanism of this regulation still remains poorly understood. In our study, we found that epithelial cell senescence was elevated after lipopolysaccharide (LPS) exposure in vivo and in vitro, accompanied by decreased expression of ATG5 and impaired autophagy activity. To further discover the molecular regulation mechanism between cellular senescence and autophagy in LPS-treated MLE-12 cells, we demonstrated that inhibition of ATG5 could decrease autophagy levels and promote the senescence of MLE-12 cells. On the contrary, elevating the expression of ATG5 could effectively suppress LPS-induced cellular senescence via enhancing autophagy activity. In addition, we demonstrated that metformin could protect MLE-12 cells from LPS-induced senescence via increasing the expression of ATG5 and augmenting autophagy activity. Our data implicate that activation of autophagy by metformin may provide a preventive and therapeutic strategy for ALI.     

FGF21 alleviates acute liver injury by inducing the SIRT1‐autophagy signalling pathway

Liver injury can lead to different hepatic diseases, which are the mainly causes of high global mortality and morbidity. Autophagy and Sirtuin type 1 (SIRT1) have been shown protective effects in response to liver injury. Previous studies have showed that Fibroblast growth factor 21 (FGF21) could alleviate acute liver injury (ALI), but the mechanism remains unclear. Here, we verified the relationship among FGF21, autophagy and SIRT1 in carbon tetrachloride (CCl₄)‐induced ALI. We established CCl₄‐induced ALI models in C57BL/6 mice and the L02 cell line. The results showed that FGF21 was robustly induced in response to stress during the development of ALI. After exogenous FGF21 treatment in ALI models, liver damage in ALI mice was significantly reduced, as well as serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Consistently, FGF21 also greatly reduced the levels of ALT, AST, pro‐inflammatory cytokines interleukin 6 (IL6) and tumour necrosis factor‐alpha (TNFα) in ALI cell lines. Mechanistically, exogenous FGF21 treatment efficiently upregulated the expression of autophagy marker microtubule‐associated protein light chain‐3 beta (LC3 II) and autophagy key molecule coiled‐coil myosin‐like BCL2‐interacting protein (Beclin1), which was accompanied by alleviating hepatotoxicity in CCl₄‐treated wild‐type mice. Then, we examined how FGF21 induced autophagy expression and found that SIRT1 was also upregulated by FGF21 treatment. To further verify our results, we constructed an anti‐SIRT1 lentit‐RNAi to inhibit SIRT1 expression in mice and L02 cells, which reversed the protective effect of FGF21 on ALI. In summary, these results indicate that FGF21 alleviates ALI by enhancing SIRT1‐mediated autophagy.     

Targeting autophagy for drug-induced hepatotoxicity

Autophagy is a lysosomal degradation pathway for bulk cytosolic proteins and damaged organelles, and is well known to act as a cell survival mechanism. Acetaminophen (APAP) overdose can cause liver injury in animals and humans by inducing necrosis due to mitochondrial damage. We recently found that pharmacological induction of autophagy by rapamycin protects against, whereas pharmacological suppression of autophagy by chloroquine exacerbates, APAP-induced liver injury in mice. Autophagy is induced to remove APAP-induced damaged mitochondria and thus attenuates APAP-induced hepatocyte necrosis. To our surprise, we found that liver-specific Atg5 knockout mice are not more susceptible, but are resistant to APAP-induced liver injury due to compensatory effects. Our work suggests that pharmacological modulation of autophagy is a novel therapeutic approach to ameliorate APAP-induced liver injury. Moreover, our work also suggests that caution needs to be exercised when using genetic autophagy gene knockout mice for pathophysiological studies.     

Targeting autophagy for drug-induced hepatotoxicity

Autophagy is a lysosomal degradation pathway for bulk cytosolic proteins and damaged organelles, and is well known to act as a cell survival mechanism. Acetaminophen (APAP) overdose can cause liver injury in animals and humans by inducing necrosis due to mitochondrial damage. We recently found that pharmacological induction of autophagy by rapamycin protects against, whereas pharmacological suppression of autophagy by chloroquine exacerbates, APAP-induced liver injury in mice. Autophagy is induced to remove APAP-induced damaged mitochondria and thus attenuates APAP-induced hepatocyte necrosis. To our surprise, we found that liver-specific Atg5 knockout mice are not more susceptible, but are resistant to APAP-induced liver injury due to compensatory effects. Our work suggests that pharmacological modulation of autophagy is a novel therapeutic approach to ameliorate APAP-induced liver injury. Moreover, our work also suggests that caution needs to be exercised when using genetic autophagy gene knockout mice for pathophysiological studies.     

Does chemically induced hepatocyte proliferation predict liver carcinogenesis?

Cell proliferation has long been recognized as having an important role in chemically induced carcinogenesis. Based on findings that certain nongenotoxic chemical carcinogens induced cell proliferation in the same organ that had an increased incidence of tumors, it has been hypothesized that a chemically induced response of enhanced DNA synthesis and cellular division causes cancer by increasing the rate of spontaneous mutations. It was further suggested that there would be no increased human risk of cancer by non-DNA-reactive compounds at doses that do not cause a proliferative response. An evaluation of the literature on the relationship between chemically induced cell proliferation and liver carcinogenesis reveals that very few systematic cell proliferation studies have been conducted over periods of extended exposure, and in many cases the exposure concentrations were not similar to those used in the cancer studies. The proliferative response resulting from exposure to many nongenotoxic carcinogens is not well sustained, whereas the carcinogenic response by these chemicals often requires prolonged exposure. The available literature leads to the conclusion that quantitative correspondences between cellular proliferation and carcinogenic responses have not been demonstrated and do not support the hypothesis that chemically induced cell proliferation is the primary mechanism by which nongenotoxic chemicals cause liver cancer. Studies of liver carcinogenesis in two-stage models point out the need to better understand chemical effects on cell loss as well as on cell replication, and demonstrate that measurements of cell proliferation alone are not sufficient to elucidate mechanisms of tumor development.     

Regulation of autophagy protects against liver injury in liver surgery-induced ischaemia/reperfusion

Transient ischaemia and reperfusion in liver tissue induce hepatic ischaemia/reperfusion (I/R) tissue injury and a profound inflammatory response in vivo. Hepatic I/R can be classified into warm I/R and cold I/R and is characterized by three main types of cell death, apoptosis, necrosis and autophagy, in rodents or patients following I/R. Warm I/R is observed in patients or animal models undergoing liver resection, haemorrhagic shock, trauma, cardiac arrest or hepatic sinusoidal obstruction syndrome when vascular occlusion inhibits normal blood perfusion in liver tissue. Cold I/R is a condition that affects only patients who have undergone liver transplantation (LT) and is caused by donated liver graft preservation in a hypothermic environment prior to entering a warm reperfusion phase. Under stress conditions, autophagy plays a critical role in promoting cell survival and maintaining liver homeostasis by generating new adenosine triphosphate (ATP) and organelle components after the degradation of macromolecules and organelles in liver tissue. This role of autophagy may contribute to the protection of hepatic I/R-induced liver injury; however, a considerable amount of evidence has shown that autophagy inhibition also protects against hepatic I/R injury by inhibiting autophagic cell death under specific circumstances. In this review, we comprehensively discuss current strategies and underlying mechanisms of autophagy regulation that alleviates I/R injury after liver resection and LT. Directed autophagy regulation can maintain liver homeostasis and improve liver function in individuals undergoing warm or cold I/R. In this way, autophagy regulation can contribute to improving the prognosis of patients undergoing liver resection or LT.     

Regucalcin ameliorates doxorubicin-induced cytotoxicity in Cos-7 kidney cells and translocates from the nucleus to the mitochondria

Doxorubicin (DOX) is a potent anticancer drug, which can have unwanted side-effects such as cardiac and kidney toxicity. A detailed investigation was undertaken of the acute cytotoxic mechanisms of DOX on kidney cells, using Cos-7 cells as kidney cell model. Cos-7 cells were exposed to DOX for a period of 24 h over a range of concentrations, and the LC₅₀ was determined to be 7 µM. Further investigations showed that cell death was mainly via apoptosis involving Ca²⁺ and caspase 9, in addition to autophagy. Regucalcin (RGN), a cytoprotective protein found mainly in liver and kidney tissues, was overexpressed in Cos-7 cells and shown to protect against DOX-induced cell death. Subcellular localization studies in Cos-7 cells showed RGN to be strongly correlated with the nucleus. However, upon treatment with DOX for 4 h, which induced membrane blebbing in some cells, the localization appeared to be correlated more with the mitochondria in these cells. It is yet to be determined whether this translocation is part of the cytoprotective mechanism or a consequence of chemically induced cell stress.     

Endocrine-active chemicals in mammary cancer causation and prevention

Endocrine-active chemicals alter or mimic physiological hormones. These compounds are reported to originate from a wide variety of sources, and recent studies have shown widespread human exposure to several of these compounds. Given the role of the sex steroid hormone, estradiol, in human breast cancer causation, endocrine-active chemicals which interfere with estrogen signaling constitute one potential factor contributing to the high incidence of breast cancer. Thus, the aim of this review is to examine several common endocrine-active chemicals and their respective roles in breast cancer causation or prevention. The plastic component, bisphenol A (BPA), the synthetic estrogen, diethylstilbestrol (DES), the by-product of organic combustion, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the soy component, genistein, and the red grape phytoalexin, resveratrol, have some degree of structural similarities to each other and estradiol. However, despite these structural similarities, the in vitro and in vivo properties of each of these chemicals vary greatly in terms of breast cancer causation and prevention. Early life exposure to BPA and DES increases rodent susceptibility to chemically induced mammary carcinogenesis, presumably through retardation of normal mammary gland maturation and/or disrupting the ratio of cell proliferation and apoptosis in the mammary gland. On the other hand, early exposures to genistein and resveratrol protect rodents against chemically induced and spontaneous mammary cancers. This is reported to occur through the ability of genistein and resveratrol to accelerate mammary gland maturation. Interestingly, TCDD, which is the most structurally dissimilar to the above chemicals and functions as an anti-estrogen, also increases chemically induced mammary carcinogenesis through retardation of mammary gland maturation. This article is part of a Special Issue entitled 'Endocrine disruptors'.     

自噬在肝再生中的作用

自噬是存在于真核细胞内的一种溶酶体依赖性的降解途径,在肝脏生理和病理过程中发挥着重要作用。肝脏具有强大的再生能力,在受到急、慢性损伤时,残肝细胞将会被激活进入细胞周期进行细胞增殖,以补偿丢失的肝组织和恢复肝功能。文章阐述了各种类型损伤之后的肝再生与自噬的关系。在物理性、酒精、食源性等因素引起的肝损伤中,肝脏通过启动自噬来促进肝再生;在化学性损伤的肝再生模型中,自噬在其中的作用仍然有争议;在病毒感染之后的肝再生中,一些嗜肝病毒（如丙肝病毒和乙肝病毒等）反而利用自噬来促进病毒颗粒复制,抑制肝再生。对自噬和肝再生机制的研究,将有助于进一步阐明再生过程,为治疗肝脏疾病提供新方法。     

Cannabidiol protects livers against nonalcoholic steatohepatitis induced by high-fat high cholesterol diet via regulating NF-κB and NLRP3 inflammasome pathway

Cannabidiol (CBD), an abundant nonpsychoactive constituent of marijuana, has been reported previously to protect against hepatic steatosis. In this study, we studied further the functions and mechanisms of CBD on liver inflammation induced by HFC diet. Mice feeding an HFC diet for 8 weeks were applied to test the protective effect of CBD on livers. RAW264.7 cells were incubated with LPS + ATP ± CBD to study the mechanisms of the effect of CBD against inflammasome activation. We found that CBD alleviated liver inflammation induced by HFC diet. CBD significantly inhibited the nuclear factor-κappa B (NF-κB) p65 nuclear translocation and the activation of nucleotide-binding domain like receptor protein 3 (NLRP3) inflammasome both in vivo and in vitro studies, which lead to the reduction of the expression of inflammation-related factors in our studies. In addition, Inhibitor of activation of NF-κB partly suppressed the NLRP3 inflammasome activation, while adding CBD further inhibited NF-κB activation and correspondingly suppressed the NLRP3 inflammasome activation in macrophages. In conclusion, the suppression of the activation of NLRP3 inflammasome through deactivation of NF-κB in macrophages by CBD might be one mechanism of its anti-inflammatory function in the liver.     

Lipoxin A4 receptor agonist BML-111 induces autophagy in alveolar macrophages and protects from acute lung injury by activating MAPK signaling

Background

Acute lung injury (ALI) is a life-threatening lung disease where alveolar macrophages (AMs) play a central role both in the early phase to initiate inflammatory responses and in the late phase to promote tissue repair. In this study, we examined whether BML-111, a lipoxin A4 receptor agonist, could alter the phenotypes of AM and thus present prophylactic benefits for ALI.

Methods

In vitro, isolated AMs were treated with lipopolysaccharide (LPS) to induce ALI. In response to BML-111 pre-treatment, apoptosis and autophagy of AMs were examined by flow cytometry, and by measuring biomarkers for each process. The potential involvement of MAPK1 and mTOR signaling pathway was analyzed. In vivo, an LPS-induced septic ALI model was established in rats and the preventative significance of BML-111 was assessed. On the cellular and molecular levels, the pro-inflammatory cytokines TNF-α and IL-6 from bronchoalveolar lavage were measured by ELISA, and the autophagy in AMs examined using Western blot.

Results

BML-111 inhibited apoptosis and induced autophagy of AMs in response to ALI inducer, LPS. The enhancement of autophagy was mediated through the suppression of MAPK1 and MAPK8 signaling, but independent of mTOR signaling. In vivo, BML-111 pre-treatment significantly alleviated LPS-induced ALI, which was associated with the reduction of apoptosis, the dampened production of pro-inflammatory cytokines in the lung tissue, as well as the increase of autophagy of AMs.

Conclusions

This study reveals the prophylactic significance of BML-111 in ALI and the underlying mechanism: by targeting the MAPK signaling but not mTOR pathway, BML-111 stimulates autophagy in AMs, attenuates the LPS-induced cell apoptosis, and promotes the resolution of ALI.

     

PPARγ/NF-κB and TGF-β1/Smad pathway are involved in the anti-fibrotic effects of levo-tetrahydropalmatine on liver fibrosis

Liver fibrosis is a necessary stage in the development of chronic liver diseases to liver cirrhosis. This study aims to investigate the anti-fibrotic effects of levo-tetrahydropalmatine (L-THP) on hepatic fibrosis in mice and cell models and its underlying mechanisms. Two mouse hepatic fibrosis models were generated in male C57 mice by intraperitoneal injection of carbon tetrachloride (CCl4) for 2 months and bile duct ligation (BDL) for 14 days. Levo-tetrahydropalmatine was administered orally at doses of 20 and 40 mg/kg. An activated LX2 cell model induced by TGF-β1 was also generated. The results showed that levo-tetrahydropalmatine alleviated liver fibrosis by inhibiting the formation of extracellular matrix (ECM) and regulating the balance between TIMP1 and MMP2 in the two mice liver fibrosis models and cell model. Levo-tetrahydropalmatine inhibited activation and autophagy of hepatic stellate cells (HSCs) by modulating PPARγ/NF-κB and TGF-β1/Smad pathway in vivo and in vitro. In conclusion, levo-tetrahydropalmatine attenuated liver fibrosis by inhibiting ECM deposition and HSCs autophagy via modulation of PPARγ/NF-κB and TGF-β1/Smad pathway.     

Young plasma reverses age‐dependent alterations in hepatic function through the restoration of autophagy

Recent studies showing the therapeutic effect of young blood on aging‐associated deterioration of organs point to young blood as the solution for clinical problems related to old age. Given that defective autophagy has been implicated in aging and aging‐associated organ injuries, this study was designed to determine the effect of young blood on aging‐induced alterations in hepatic function and underlying mechanisms, with a focus on autophagy. Aged rats (22 months) were treated with pooled plasma (1 ml, intravenously) collected from young (3 months) or aged rats three times per week for 4 weeks, and 3‐methyladenine or wortmannin was used to inhibit young blood‐induced autophagy. Aging was associated with elevated levels of alanine transaminase and aspartate aminotransferase, lipofuscin accumulation, steatosis, fibrosis, and defective liver regeneration after partial hepatectomy, which were significantly attenuated by young plasma injections. Young plasma could also restore aging‐impaired autophagy activity. Inhibition of the young plasma‐restored autophagic activity abrogated the beneficial effect of young plasma against hepatic injury with aging. In vitro, young serum could protect old hepatocytes from senescence, and the antisenescence effect of young serum was abrogated by 3‐methyladenine, wortmannin, or small interfering RNA to autophagy‐related protein 7. Collectively, our data indicate that young plasma could ameliorate age‐dependent alterations in hepatic function partially via the restoration of autophagy.     

Autophagy and pathogens: «Bon appétit Messieurs!»

Autophagy is a highly conserved, self-degradative pathway for clearance and recycling of cytoplasmic contents. This ubiquitous cell intrinsic process can be used as a defence mechanism against intracellular pathogens. Indeed autophagy is increased upon pathogen detection, and experimental extinction in vitro and in vivo of this cellular process has been demonstrated as a crucial role to control intracellular pathogens. Co-evolution between host-cells and pathogens has selected numerous micoorganisms able to avoid or usurp autophagy to their own benefit. Understanding mechanisms underlying the anti-microbial properties of autophagy as well as those used by certain pathogens to escape this cellular process might be crucial to manipulate this cellular function in order to prevent or treat infectious diseases.     

DNA ploidy and autophagic protein degradation as determinants of hepatocellular growth and survival

Hepatocytes have the ability to go through specialized cell cycles, which, during normal developmental liver growth, result in the formation of binuclear and polyploid cells. In the adult rat liver, the majority of the hepatocytes (about 70%) are tetraploid, 15-20% are octoploid, and only 10-15% are diploid (about 50% in humans). One-third of the hepatocytes in either rats or humans are binuclear (with two diploid or two tetraploid nuclei). Among cultured rat hepatocytes stimulated with growth factors (EGF and insulin), one-half of the mitoses are of the binucleating type (suggesting a "quantal" mechanism), causing one-third of the postmitotic cells to become binuclear. In contrast, regenerative liver growth, induced by partial hepatectomy, is predominantly nonbinucleating. During rat liver carcinogenesis, the early populations of phenotypically altered cells (foci) are predominantly diploid, as are the later neoplastic nodules and carcinomas, which can be shown to have a regeneration-like, largely nonbinucleating growth pattern. A negative correlation between growth capacity and ploidy can be demonstrated in cultured hepatocytes, regenerating livers, neoplastic nodules, and hepatocellular carcinomas, suggesting that suppression of binucleation and polyploidization may carry a growth advantage, in addition to helping to maintain a large population of diploid, potential stem cells. Since a diploid genome is less protected against mutagenic change than a polyploid genome, diploid tumor cells may, furthermore, be more prone than polyploid cells to undergo mutation-based progression toward increasing malignancy. The ability of liver tumor promoters like 2-acetylaminofluorene, cyproterone acetate, -hexachlorocyclohexane and methylclofenapate to induce nonbinucleating hepatocyte growth may, therefore, cooperate with the selective growth stimulation of cancer cells and cancer cell precursors to promote liver carcinogenesis.Autophagy, a mechanism for the bulk degradation of cytoplasm, contributes to intracellular protein turnover and serves to restrict cellular growth. Rat liver carcinogenesis is accompanied by a progressive reduction of autophagic capacity, preneoplastic livers having 50% and hepatocellular carcinoma cells only 20% as much autophagy as normal hepatocytes. The ascites hepatoma cell line AH-130 has virtually no autophagy during logarithmic growth, but some autophagy is turned on when the cells become growth-arrested at high cell density. Ascitic fluid from AH-130 cells is able to completely inhibit autophagy in normal hepatocytes, suggesting that the cancer cells may improve their growth ability through an autocrine, autophagy-suppressive mechanism. Hepatocytes from preneoplastic livers similarly maintain a low autophagic activity under restrictive culture conditions, thereby surviving much better than normal hepatocytes, which switch on their autophagy. In the presence of an autophagy inhibitor (3-methyladenine), normal and preneoplastic hepatocytes survive equally well, testifying to the importance of autophagy as a determinant of cell survival and growth.     

Cutting edge: estrogen drives expansion of the CD4+CD25+ regulatory T cell compartment

CD4(+)CD25(+) regulatory T cells are crucial to the maintenance of tolerance in normal individuals. However, the factors regulating this cell population and its function are largely unknown. Estrogen has been shown to protect against the development of autoimmune disease, yet the mechanism is not known. We demonstrate that estrogen (17-beta-estradiol, E2) is capable of augmenting FoxP3 expression in vitro and in vivo. Treatment of naive mice with E2 increased both CD25(+) cell number and FoxP3 expression level. Further, the ability of E2 to protect against autoimmune disease (experimental autoimmune encephalomyelitis) correlated with its ability to up-regulate FoxP3, as both were reduced in estrogen receptor alpha-deficient animals. Finally, E2 treatment and pregnancy induced FoxP3 protein expression to a similar degree, suggesting that high estrogen levels during pregnancy may help to maintain fetal tolerance. In summary, our data suggest E2 promotes tolerance by expanding the regulatory T cell compartment.     

Involvement of autophagy induction in penta-1,2,3,4,6-O-galloyl-β-D-glucose-induced senescence-like growth arrest in human cancer cells

Growing evidence has demonstrated that autophagy plays important and paradoxical roles in carcinogenesis, while senescence is considered to be a crucial tumor-suppressor mechanism in cancer prevention and treatment. In the present study we demonstrated that both autophagy and senescence were induced in response to penta-1,2,3,4,6-O-galloyl-β-D-glucose (PGG), a chemopreventive polyphonolic compound, in multiple types of cancer cells. Analysis of these 2 events over the experimental time course indicated that autophagy and senescence occurred in parallel early in the process and dissociated later. The long-term culture study suggested that a subpopulation of senescent cells may have the capacity to reenter the cell cycle. Inhibition of autophagy by either a chemical inhibitor or RNA interference led to a significant reduction of PGG-induced senescence, followed by induction of apoptosis. These results suggested that autophagy promoted senescence induction by PGG and that PGG might exert its anticancer activity through autophagy-mediated senescence. For the first time, these findings uncovered the relationships among autophagy, senescence, and apoptosis induced by PGG. In addition, we identified that unfolded protein response signaling played a pivotal role in the autophagy-mediated senescence phenotype. Furthermore, our data showed that activation of MAPK8/9/10 (mitogen-activated protein kinase 8/9/10/c-Jun N-terminal kinases) was an essential upstream signal for PGG-induced autophagy. Finally, the key in vitro results were validated in vivo in a xenograft mouse model of human HepG2 liver cancer. Our findings provided novel insights into understanding the mechanisms and functions of PGG-induced autophagy and senescence in human cancer cells.     

Research Article: Involvement of autophagy induction in penta-1,2,3,4,6-O-galloyl-β-D-glucose-induced senescence-like growth arrest in human cancer cells

Growing evidence has demonstrated that autophagy plays important and paradoxical roles in carcinogenesis, while senescence is considered to be a crucial tumor-suppressor mechanism in cancer prevention and treatment. In the present study we demonstrated that both autophagy and senescence were induced in response to penta-1,2,3,4,6-O-galloyl-β-D-glucose (PGG), a chemopreventive polyphonolic compound, in multiple types of cancer cells. Analysis of these 2 events over the experimental time course indicated that autophagy and senescence occurred in parallel early in the process and dissociated later. The long-term culture study suggested that a subpopulation of senescent cells may have the capacity to reenter the cell cycle. Inhibition of autophagy by either a chemical inhibitor or RNA interference led to a significant reduction of PGG-induced senescence, followed by induction of apoptosis. These results suggested that autophagy promoted senescence induction by PGG and that PGG might exert its anticancer activity through autophagy-mediated senescence. For the first time, these findings uncovered the relationships among autophagy, senescence, and apoptosis induced by PGG. In addition, we identified that unfolded protein response signaling played a pivotal role in the autophagy-mediated senescence phenotype. Furthermore, our data showed that activation of MAPK8/9/10 (mitogen-activated protein kinase 8/9/10/c-Jun N-terminal kinases) was an essential upstream signal for PGG-induced autophagy. Finally, the key in vitro results were validated in vivo in a xenograft mouse model of human HepG2 liver cancer. Our findings provided novel insights into understanding the mechanisms and functions of PGG-induced autophagy and senescence in human cancer cells.     

Caveolin-1 identified as a key mediator of acute lung injury using bioinformatics and functional research

Acute lung injury (ALI) is a potentially life-threatening, devastating disease with an extremely high rate of mortality. The underlying mechanism of ALI is currently unclear. In this study, we aimed to confirm the hub genes associated with ALI and explore their functions and molecular mechanisms using bioinformatics methods. Five microarray datasets available in GEO were used to perform Robust Rank Aggregation (RRA) to identify differentially expressed genes (DEGs) and the key genes were identified via the protein-protein interaction (PPI) network. Lipopolysaccharide intraperitoneal injection was administered to establish an ALI model. Overall, 40 robust DEGs, which are mainly involved in the inflammatory response, protein catabolic process, and NF-κB signaling pathway were identified. Among these DEGs, we identified two genes associated with ALI, of which the CAV-1/NF-κB axis was significantly upregulated in ALI, and was identified as one of the most effective targets for ALI prevention. Subsequently, the expression of CAV-1 was knocked down using AAV-shCAV-1 or CAV-1-siRNA to study its effect on the pathogenesis of ALI in vivo and in vitro. The results of this study indicated that CAV-1/NF-κB axis levels were elevated in vivo and in vitro, accompanied by an increase in lung inflammation and autophagy. The knockdown of CAV-1 may improve ALI. Mechanistically, inflammation was reduced mainly by decreasing the expression levels of CD3 and F4/80, and activating autophagy by inhibiting AKT/mTOR and promoting the AMPK signaling pathway. Taken together, this study provides crucial evidence that CAV-1 knockdown inhibits the occurrence of ALI, suggesting that the CAV-1/NF-κB axis may be a promising therapeutic target for ALI treatment.Subject terms: Cell signalling, Respiratory tract diseases