The inhibitory action of PDCD4 in lipopolysaccharide/D-galactosamine-induced acute liver injury

Modulation of long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression in the liver of Beagle dogs by Toxocara canis infection

BACKGROUND

Long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) play crucial roles in regulating various physiological and pathological processes. However, the role of lncRNAs and mRNAs in mediating the liver response during Toxocara canis infection remains incompletely understood.

METHODS

In the present study, the expression profile of lncRNAs and mRNAs was investigated in the liver of Beagle dogs infected by T. canis using high-throughput RNA sequencing.

RESULTS

Compared with the control groups, 876 differentially expressed (DE) lncRNAs and 288 DEmRNAs were identified at 12 h post-infection (hpi), 906 DElncRNAs and 261 DEmRNAs were identified at 24 hpi, and 876 DElncRNAs and 302 DEmRNAs were identified at 36 days post-infection (dpi). A total of 16 DEmRNAs (e.g. dpp4, crp and gnas) were commonly identified at the three infection stages. Enrichment and co-localization analyses identified several pathways involved in immune and inflammatory responses during T. canis infection. Some novel DElncRNAs, such as LNC_015756, LNC_011050 and LNC_011052, were also associated with immune and inflammatory responses. Also, LNC_005105 and LNC_005401 were associated with the secretion of anti-inflammatory cytokines, which may play a role in the healing of liver pathology at the late stage of infection.

CONCLUSIONS

Our data provided new insight into the regulatory roles of lncRNAs and mRNAs in the pathogenesis of T. canis and improved our understanding of the contribution of lncRNAs and mRNAs to the immune and inflammatory response of the liver during T. canis infection.

Pdcd4 promotes lipid deposition by attenuating PPARα-mediated fatty acid oxidation in hepatocytes

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation in hepatocytes. The involvement of programmed cell death 4 (Pdcd4) in inflammation and metabolic diseases has been widely reported. However, the precise regulatory role of Pdcd4 in hepatocytic lipid metabolism and NAFLD is not well known.

RESEARCH DESIGN AND METHODS

We established a high-fat diet-induced NAFLD (HFD-NAFLD) rat model and a free fatty acids (FFAs)-treated cell model, and analyzed the expression and distribution of PDCD4. The lentivirus for Pdcd4 knockout and the vector for Pdcd4 overexpression were used to alter Pdcd4 expression in BRL 3A cells. Thereafter, lipid accumulation, FA metabolic gene expression, and peroxisome proliferator-activated receptor alpha (Pparα)-dependent peroxisomal β-oxidation-related gene expression, especially that of the critical transcription factors and enzymes acyl-CoA oxidases 1-3 (Acox1-3), were detected both at the mRNA and protein levels.

RESULTS

PDCD4 expression increased and it was mainly distributed in hepatocyte nuclei of the HFD-NAFLD rats. as well as the FFAs-treated CBRH-7919 and BRL 3A cell lines. Pdcd4 knockout significantly suppressed FFAs-induced lipid accumulation, and Pdcd4 overexpression accelerated FFAs-induced lipid accumulation in hepatocytes. Mechanistically, Pdcd4 negatively regulated the expression Pparα and Acox1-3. In addition, rescue experiments confirmed that Pparα knockdown could attenuate the expression of Acox1-3 in Pdcd4 knockout cells, which ultimately restored lipid deposition to normal levels. PPARα expression decreased in the liver of the HFD-NAFLD rats. The enrichment of PDCD4 in hepatocyte nuclei correlated with lower PPARα expression after FFAs treatment in vitro.

CONCLUSION

Our results indicate that the abundance of PDCD4 under high-fat conditions facilitates hepatocellular lipid accumulation by decreasing PPARα-dependent FA peroxisomal β-oxidation.

MicroRNA-21 Plays Multiple Oncometabolic Roles in Colitis-Associated Carcinoma and Colorectal Cancer via the PI3K/AKT, STAT3, and PDCD4/TNF-α Signaling Pathways in Zebrafish

Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. Patients with inflammatory bowel disease (IBD) have a high risk of developing CRC. Inflammatory cytokines are regulated by complex gene networks and regulatory RNAs, especially microRNAs. MicroRNA-21 (miR-21) is amongst the most frequently upregulated microRNAs in inflammatory responses and cancer development. miR-21 has become a target for genetic and pharmacological regulation in various diseases. However, the association between inflammation and tumorigenesis in the gut is largely unknown. Hence, in this study, we generated a zebrafish model (ImiR-21) with inducible overexpression of miR-21 in the intestine. The results demonstrate that miR-21 can induce CRC or colitis-associated cancer (CAC) in ImiR-21 through the PI3K/AKT, PDCD4/TNF-α, and IL-6/STAT3 signaling network. miR-21 activated the PI3K/AKT and NF-κB signaling pathways, leading to initial inflammation; thereafter, miR-21 and TNF-α repressed PDCD4 and its tumor suppression activity. Eventually, active STAT3 stimulated a strong inflammatory response and activated the invasion/metastasis process of tumor cells. Hence, our findings indicate that miR-21 is critical for the development of CRC/CAC via the PI3K/AKT, STAT3, and PDCD4/TNF-α signaling networks.

PDCD4 Simultaneously Promotes Microglia Activation via PDCD4-MAPK-NF-κB Positive Loop and Facilitates Neuron Apoptosis During Neuroinflammation

Neuroinflammation and neuron injury are common features of the central nervous system (CNS) diseases. It is of great significance to identify their shared key regulatory molecules and thus explore the potential therapeutic targets. Programmed cell death factor 4 (PDCD4), an apoptosis-related molecule, extensively participates in tumorigenesis and inflammatory diseases, but its expression and biological function during CNS neuroinflammation remain unclear. In the present study, utilizing the lipopolysaccharide (LPS)-induced neuroinflammation model in mice, we reported an elevated expression of PDCD4 both in injured neurons and activated microglia of the inflamed brain. A similar change in PDCD4 expression was observed in vitro in the microglial activation model. Silencing PDCD4 by shRNA significantly inhibited the phosphorylation of MAPKs (p38, ERK, and JNK), prevented the phosphorylation and nuclear translocation of NF-κB p65, and thus attenuated the LPS-induced microglial inflammatory activation. Interestingly, LPS also required the MAPK/NF-κB signaling activation to boost PDCD4 expression in microglia, indicating the presence of a positive loop. Moreover, a persistent elevation of PDCD4 expression was detected in the H₂O₂-induced neuronal oxidative damage model. Knocking down PDCD4 significantly inhibited the expression of pro-apoptotic proteins BAX and Cleaved-PARP, suggesting the proapoptotic activity of PDCD4 in neurons. Taken together, our data indicated that PDCD4 may serve as a hub regulatory molecule that simultaneously promotes the microglial inflammatory activation and the oxidative stress-induced neuronal apoptosis within CNS. The microglial PDCD4-MAPK-NF-κB positive feedback loop may act as pivotal signaling for neuroinflammation which subsequently exaggerates neuronal injury, and thus may become a potential therapeutic target for neuroinflammatory diseases.

Elevated microRNA-21 Is a Brake of Inflammation Involved in the Development of Nasal Polyps

Background

CRSwNP is an inflammatory disease but the mechanism is not yet fully understood. MiR-21, a member of miRNAs, has been reported to play roles in mediating inflammation. However, the expression of miR-21 and its role in patients with CRSwNP remain elusive.

Methods

Turbinates from control subjects, uncinate processes from CRSsNP, polyp tissues from CRSwNP, and nasal epithelial cells brushed from nasal mucosa were collected. The expression of miR-21 and cytokines in nasal tissues and epithelial cells were detected by qPCR. The localization of miR-21 was detected by ISH, and its target was identified by bioinformation analysis, qPCR, IHC, WB, and luciferase reporter system. The protein and mRNA of PDCD4 and NF-κB P65 were determined by WB and qPCR after miR-21 transfection in HNEpC. The role of miR-21 on cytokines was analyzed in HNEpC and nasal polyp explants.

Results

MiR-21 was upregulated in CRSwNP relative to control subjects by qPCR, which was determined mainly in nasal epithelial cells of CRSwNP by ISH. Both pro-inflammation cytokines (IL-1β, IL-6, IL-8, IL-25, and TSLP) and a suppressive cytokine (IL-10) were overexpressed in the epithelial cells of CRSwNP. The expression of miR-21 was positively correlated with IL-10 and negatively correlated with IL-6, IL-8, IL-33, and TSLP in the epithelial cells of CRSwNP. As a potential target of miR-21, the expression of PDCD4 was negatively correlated with miR-21 in CRSwNP. In HNEpC, miR-21 could reduce the expression of PDCD4 at both mRNA and protein levels, and bioinformation analysis and luciferase reporter system confirmed PDCD4 as one target of miR-21. Furthermore, miR-21 could decrease the activation of NF-κB and increase IL-10 mRNA. Both SEB and LPS could elevate miR-21, with IL-25, IL-33, TSLP induced by SEB and IL-1β, IL-6, IL-8 induced by LPS, while the miR-21 could regulate the expression of IL-33, TSLP, IL-1β, IL- 6 and IL-8 in vitro and ex vivo. Clinically, miR-21 expression was inversely correlated with the Lund-Mackay CT scores and the Lund-Kennedy scores in CRSwNP.

Conclusion

MiR-21 could be a prominent negative feedback factor in the inflammation process to attenuate the expression of pro-inflammatory cytokines, thereby playing an anti-inflammation role in CRSwNP.

Analysis of miRNA expression changes in bovine endometrial stromal cells treated with lipopolysaccharide

After parturition, bovine uterine stromal cells are often exposed to complex bacterial and viral stimuli owing to epithelial cell rupture, resulting in an inflammatory response. In this study, we used an in vitro model to study the response of bovine endometrial stromal cells to inflammatory mediators and the associated regulated microRNAs in response to lipopolysaccharide. Lipopolysaccharide (LPS) is a bacterial wall component in gram-negative bacteria that causes inflammation upon immune recognition, which is used to create in vitro inflammation models. Thus, we used high-throughput RNA sequencing to identify miRNAs that may have an anti-inflammatory role in the LPS-induced inflammatory response. Two groups of bovine uterine cells were treated with phosphate buffer saline (PBS) and LPS, respectively. Compared with the control (PBS) group, the LPS-treated group had 219 differentially expressed miRNAs, of which 113 were upregulated, and 106 were downregulated. Gene ontology enrichment analysis revealed that the target genes of differentially expressed miRNAs were significantly enriched in several activities, such as transferase activity, small molecule binding, and protein binding. Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the target genes of differential miRNAs were significantly enriched in fluid shear stress and atherosclerosis, MAPK signaling pathway, TNF signaling pathway. By analyzing differentially expressed miRNAs, we found that miR-200c, miR-1247-3p, and let-7b are directly related to the inflammatory response. For instance, miR-200c target genes (MAP3K1, MAP4K3, MAPKAPK5, MAP3K8, MAP3K5) and let-7b target genes (CASP3, IL13, MAPK8, CXCL10) were significantly enriched in the MAPK and IL-17 signaling pathways, respectively. In summary, our research provides insight into the molecular mechanism underlying LPS-induced inflammation in vitro, which may unveil new targets for the treatment of endometritis.

MicroRNA-21 maintains hematopoietic stem cell homeostasis through sustaining the NF-κB signaling pathway in mice

Long-term hematopoietic output is dependent on hematopoietic stem cell (HSC) homeostasis which is maintained by a complex molecular network in which microRNA play crucial roles, although the underlying molecular basis has not been fully elucidated. Here we show that microRNA-21 (miR-21) is enriched in murine HSC, and that mice with conditional knockout of miR-21 exhibit an obvious perturbation in hematopoiesis. Moreover, significant loss of HSC quiescence and long-term reconstituting ability are observed in the absence of miR-21. Further studies revealed that miR-21 deficiency markedly decreases the nuclear factor kappa B (NF-B) pathway, accompanied by increased expression of PDCD4, a direct target of miR-21, in HSC. Interestingly, overexpression of PDCD4 in wild-type HSC generates similar phenotypes as those of miR-21-deficient HSC. More importantly, knockdown of PDCD4 can significantly rescue the attenuation of NF-B activity, thereby improving the defects in miR-21-null HSC. On the other hand, we found that miR-21 is capable of preventing HSC from ionizing radiation- induced DNA damage via activation of the NF-B pathway. Collectively, our data demonstrate that miR-21 is involved in maintaining HSC homeostasis and function, at least in part, by regulating the PDCD4-mediated NF-B pathway and provide a new insight into radioprotection of HSC.

Programmed cell death factor 4 (PDCD4), a novel therapy target for metabolic diseases besides cancer

Programmed cell death factor 4 (PDCD4) is originally described as a tumor suppressor gene that exerts antineoplastic effects by promoting apoptosis and inhibiting tumor cell proliferation, invasion, and metastasis. Several investigations have probed the aberrant expression of PDCD4 with the progression of metabolic diseases, such as polycystic ovary syndrome (PCOS), obesity, diabetes, and atherosclerosis. It has been ascertained that PDCD4 causes glucose and lipid metabolism disorders, insulin resistance, oxidative stress, chronic inflammatory response, and gut flora disorders to regulate the progression of metabolic diseases. This review aims to summarize the latest researches to uncover the structure, expression regulation, and biological functions of PDCD4 and to elucidate the regulatory mechanism of the development of tumors and metabolic diseases. This review has emphasized the understanding of the PDCD4 role and to provide new ideas for the research, diagnosis, and treatment of tumors and metabolic diseases.

4-hydroxybenzo[d]oxazol-2(3H)-one ameliorates LPS/D-GalN-induced acute liver injury by inhibiting TLR4/NF-κB and MAPK signaling pathways in mice

The purpose of this study was to synthesize 4-hydroxybenzo[d]oxazol-2(3H)-one (HBO) and to investigate its protective effects on lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver injury. HBO (C₇H₅O₃N) was synthesized based on 2-nitro-resorcinol and identified by physicochemical analysis. In the animal experiment, mice were pretreated with HBO (50, 100, 200 mg/kg) for 10 days. At the end of pretreatment, the animals were injected with LPS (10 µg/kg)/D-GalN (700 mg/kg). The results showed that HBO significantly alleviated liver injury induced by LPS/D-GalN in mice. It remarkably decreased inflammatory response by reducing the levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Moreover, HBO notably attenuated hepatocyte apoptosis by inhibiting the release of Cytochrome C (Cyt C) from mitochondria into the cytoplasm and regulating the expression of B-cell lymphoma-2 (Bcl-2) family. Furthermore, the result showed that HBO inhibited the expressions of nuclear factor kappa-B p50 (NF-κBp50), toll-like receptor 4 (TLR4), and myeloid differentiation factor 88 (MyD88), as well as the phosphorylation of inhibitor of nuclear factor kappa-B (IκB), inhibitor of nuclear factor kappa-B kinase-α/β (IKK-α/β), nuclear factor kappa-B p65 (NF-κBp65), suggesting that HBO had a certain influence on the TLR4/NF-κB pathway. In addition, the mitogen-activated protein kinase (MAPK) signaling pathway was also affected by HBO, as evidenced by the decrease in the phosphorylation levels of extracellular regulated protein kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38). In conclusion, our study suggested that HBO could protect against LPS/D-GalN-induced liver injury, moreover, treatment with HBO appeared to be capable of further regulating the TLR4/NF-κB and MAPK signaling pathways.

AKT activator SC79 protects hepatocytes from TNF-α-mediated apoptosis and alleviates d-Gal/LPS-induced liver injury

Tumor necrosis factor-α (TNF-α) is a highly pleiotropic cytokine executing biological functions as diverse as cell proliferation, metabolic activation, inflammatory responses, and cell death. TNF-α can induce multiple mechanisms to initiate apoptosis in hepatocytes leading to the subsequent liver injury. Since the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) pathway is known to have a protective role in death factor-mediated apoptosis, it is our hypothesis that activation of Akt may represent a therapeutic strategy to alleviate TNF-α-induced hepatocyte apoptosis and liver injury. We report here that the Akt activator SC79 protects hepatocytes from TNF-α-induced apoptosis and protects mice from d-galactosamine (d-Gal)/lipopolysaccharide (LPS)-induced TNF-α-mediated liver injury and damage. SC79 not only enhances the nuclear factor-κB (NF-κB) prosurvival signaling in response to TNF-α stimulation, but also increases the expression of cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein L and S (FLIP_L/S), which consequently inhibits the activation of procaspase-8. Furthermore, pretreatment of the PI3K/Akt inhibitor LY294002 reverses all the SC79-induced hepatoprotective effects. These results strongly indicate that SC79 protects against TNF-α-induced hepatocyte apoptosis and suggests that SC79 is likely a promising therapeutic agent for ameliorating the development of liver injury. NEW & NOTEWORTHY SC79 protects hepatocytes from TNF-α-mediated apoptosis and mice from Gal/LPS-induced liver injury and damage. Cytoprotective effects of SC79 against TNF-α act through both AKT-mediated activation of NF-κB and upregulation of FLIP_L/S.

Andrographolide ameliorates d-galactosamine/lipopolysaccharide-induced acute liver injury by activating Nrf2 signaling pathway

Andrographolide (ADH), a diterpenoid lactone extracted from Andrographis paniculata, has been found to have anti-inflammatory and anti-oxidative effects. However, its protective effects and mechanisms on liver injury have not been investigated clearly. This study takes an attempt to reveal the protective effects and mechanism of ADH on lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced acute liver injury in mice. The mice liver injury model was induced by LPS (60 mg/kg) and D-GalN (800 mg/kg), and ADH was given 1 h after LPS and D-GalN treatment. Hepatic tissue histology was measured by H&E staining. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were detected by detection kits. The levels of TNF-α and IL-1β were detected by ELISA. Moreover, malondialdehyde (MDA) and reactive oxygen species (ROS) contents were also detected. Meanwhile, the expression of Nrf2, HO-1, and NF-κB were detected by western blot analysis. The results showed that ADH treatment improved liver histology and decreased the levels of ALT, AST, MPO, IL-1β, TNF-α, as well as MDA and ROS levels of hepatic tissues in a dose-dependent manner. ADH also inhibited LPS/D-GalN-induced NF-κB activation. The expression of Nrf2 and HO-1 were increased by treatment of ADH. In conclusion, ADH protected against LPS/D-GalN-induced liver injury by inhibiting NF-κB and activating Nrf2 signaling pathway.

Oxyresveratrol prevents lipopolysaccharide/d-galactosamine-induced acute liver injury in mice

Oxyresveratrol (Oxy) is a natural polyhydroxystilbene abundant in mulberry that has anti-inflammation and anti-oxidant activities. We evaluated the protective effect of Oxy in the context of the lipopolysaccharide and d-galactosamine (LPS/d-GalN) induced acute liver injury. Oxy restricted the development of histopathological changes, markedly reduced the activity of alanine transaminase (ALT) and aspartate transaminase (AST), which are indicators of impaired liver function. Oxy significantly regulated the contents of oxidative stress related enzymes and products, and inhibited expressions of inflammatory mediators and cytokines. Oxy treatment diminished the Toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB) signaling pathway in liver, activated the Kelch-like ECH-associated protein 1(Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, and increased expressions of heme oxygenase 1 (HO-1) and quinine oxidoreductase 1(NQO1). Pretreatment with Oxy decreased LPS/d-GalN stimulated hepatocyte apoptosis by efficaciously raising the B-cell lymphoma 2 (Bcl-2)/Bcl-2 associated X (Bax) ratio, inhibiting the expression and activation of caspases, and activating the phosphoinoside-3-kinase (PI3K)-Akt pathway. Our results demonstrate the hepatoprotective efficacy of Oxy. The protection is mainly due to the prevention of TLR4/NF-κB pathway activation, induced activation of Keap1-Nrf2 signaling pathway, and decreased hepatocyte apoptosis. Oxy warrants further study as a potential therapeutic agent candidate for the management of acute liver injury.

Role of Human Wharton's Jelly Derived Mesenchymal Stem Cells (WJ-MSCs) for Rescue of d-Galactosamine Induced Acute Liver Injury in Mice

BACKGROUND/AIM

Mesenchymal stem cells (MSCs) are multipotent precursor cells having self-renewal ability making them a candidate for use in regenerative medicine. Acute liver injury results in sudden loss of hepatic function leading to organ failure. Liver transplantation is often required to salvage patients with acute liver failure. Due to shortage of organs, identification of alternate method is the need of the hour. In view of this, an attempt has been made to check the regenerative ability of WJ-MSCs (wharton's jelly derived MSC) in mice models for acute liver injury.

METHODS

Swiss albino mice weighing 25 ± 5 g were used in this study. The control mice (Group I), was given saline. Group II mice received d-Galactosamine (d-GalN-800 mg/kg; i.p). Group III mice similar with Group II, received WJ-MSCs (5 × 105 cells/0.5 ml DMEM) through tail vein, 24 h after d-GalN administration and Group IV mice received MSC alone.

RESULTS

Parameters, indicative of hepatotoxicity and oxidative stress were analyzed. A two-fold elevation in the marker enzymes of liver toxicity such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (SAP), and total serum bilirubin (TBIL) confirms hepatocellular injury, while a greater than four-fold increase in malondialdehyde (MDA) formation, along with around 40% fall in superoxide-dis-mutase (SOD) activity was indicative of oxidative stress and loss of hepatocellular membrane integrity induced by d-GalN. The above biochemical and pathological changes were significantly restored in mice that received WJ-MSCs indicating hepatoprotective and probable regenerative property.

CONCLUSION

The present study showed that WJ-MSC treatment is able to rescue/ameliorate the hepatotoxicity induced by d-GalN in mice.

Asiatic Acid Exhibits Anti-inflammatory and Antioxidant Activities against Lipopolysaccharide and d-Galactosamine-Induced Fulminant Hepatic Failure

Inflammation and oxidative stress are essential for the pathogenesis of fulminant hepatic failure (FHF). Asiatic acid (AA), which is a pentacyclic triterpene that widely occurs in various vegetables and fruits, has been reported to possess antioxidant and anti-inflammatory properties. In this study, we investigated the protective effects of AA against lipopolysaccharide (LPS) and d-galactosamine (GalN)-induced FHF and the underlying molecular mechanisms. Our findings suggested that AA treatment effectively protected against LPS/d-GalN-induced FHF by lessening the lethality; decreasing the alanine transaminase and aspartate aminotransferase levels, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α production, malondialdehyde formation, myeloperoxidase level and reactive oxygen species generation (i.e., H₂O₂, NO, and O2−), and increasing the glutathione and superoxide dismutase contents. Moreover, AA treatment significantly inhibited mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathway activation via the partial induction of programmed cell death 4 (PDCD4) protein expressions, which are involved in inflammatory responses. Furthermore, AA treatment dramatically induced the expression of the glutamate-cysteine ligase modifier subunit, the glutamate-cysteine ligase catalytic subunit, heme oxygenase-1, and NAD (P) H: quinoneoxidoreductase 1 (NQO1), which are largely dependent on activation of the nuclear factor-erythroid 2-related factor 2 (Nrf2) through the induction of AMP-activated protein kinase (AMPK) and glycogen synthase kinase-3β (GSK3β) phosphorylation. Accordingly, AA exhibited protective roles against LPS/d-GalN-induced FHF by inhibiting oxidative stress and inflammation. The underlying mechanism may be associated with the inhibition of MAPK and NF-κB activation via the partial induction of PDCD4 and upregulation of Nrf2 in an AMPK/GSK3β pathway activation-dependent manner.

SOX6 and PDCD4 enhance cardiomyocyte apoptosis through LPS-induced miR-499 inhibition

Sepsis-induced cardiac apoptosis is one of the major pathogenic factors in myocardial dysfunction. As it enhances numerous proinflammatory factors, lipopolysaccharide (LPS) is considered the principal mediator in this pathological process. However, the detailed mechanisms involved are unclear. In this study, we attempted to explore the mechanisms involved in LPS-induced cardiomyocyte apoptosis. We found that LPS stimulation inhibited microRNA (miR)-499 expression and thereby upregulated the expression of SOX6 and PDCD4 in neonatal rat cardiomyocytes. We demonstrate that SOX6 and PDCD4 are target genes of miR-499, and they enhance LPS-induced cardiomyocyte apoptosis by activating the BCL-2 family pathway. The apoptosis process enhanced by overexpression of SOX6 or PDCD4, was rescued by the cardiac-abundant miR-499. Overexpression of miR-499 protected the cardiomyocytes against LPS-induced apoptosis. In brief, our results demonstrate the existence of a miR-499-SOX6/PDCD4-BCL-2 family pathway in cardiomyocytes in response to LPS stimulation.

PDCD4 Deficiency Aggravated Colitis and Colitis-associated Colorectal Cancer Via Promoting IL-6/STAT3 Pathway in Mice

BACKGROUND

Although programmed cell death (PDCD) 4 is generally considered to be a new tumor suppressor, the consequence of Pdcd4 deficiency in tumorigenesis is not well established. The role of PDCD4 in colitis-associated colorectal carcinoma (CRC) remains unknown.

METHODS

Experimental colitis and CRC were induced by dextran sodium sulfate and dextran sodium sulfate with azoxymethane, respectively, in wild type and Pdcd4 knockout (Pdcd4(-/-)) mice and were evaluated by clinical examination and histopathology. Levels of cytokines were detected by enzyme-linked immunosorbent assay. Changes in signaling pathways were examined by Western blot and immunofluorescent staining. Cell proliferation was determined by BrdU incorporation and Cell Counting Kit-8 staining.

RESULTS

Pdcd4 deficiency not only aggravated the dextran sodium sulfate-induced acute colitis but also promoted the development of colitis-induced CRC. Mechanically, Pdcd4 deficiency accelerated epithelial cell proliferation during tumorigenesis, markedly up-regulated the expression of proinflammatory cytokines, such as interleukin (IL)-6, and enhanced the activation of signal transducer and activator of transcription (STAT3), a IL-6 downstream effector. Using purified cells, we found that Pdcd4 deficiency increased IL-6 expression in vitro and the susceptibility to IL-6/STAT3 pathway-mediated cell proliferation significantly. Furthermore, blockade of IL-6/STAT3 pathway through sgp130Fc reversed the promoting effect of Pdcd4 deficiency on colonic epithelial cell proliferation in vivo.

CONCLUSION

The Pdcd4 deficiency accelerates colitis and colitis-associated CRC presumably through up-regulating IL-6/STAT3 pathway, suggesting that PDCD4 plays a protective role in inflammation-associated carcinoma and might be a potential target for the treatment of CRC.

The therapeutic effect of CORM-3 on acute liver failure induced by lipopolysaccharide/D-galactosamine in mice

BACKGROUND

Acute liver failure (ALF) is a severe and life-threatening clinical syndrome resulting in a high mortality and extremely poor prognosis. Recently, a water-soluble CO-releasing molecule (CORM-3) has been shown to have anti-inflammatory effect. The present study was to investigate the effect of CORM-3 on ALF and elucidate its underlying mechanism.

METHODS

ALF was induced by a combination of LPS/D-GalN in mice which were treated with CORM-3 or inactive CORM-3 (iCORM-3). The efficacy of CORM-3 was evaluated based on survival, liver histopathology, serum aminotransferase activities (ALT and AST) and total bilirubin (TBiL). Serum levels of inflammatory cytokines (TNF-alpha, IL-6, IL-1beta and IL-10) and liver immunohistochemistry of NF-kappaB-p65 were determined; the expression of inflammatory mediators such as iNOS, COX-2 and TLR4 was measured using Western blotting.

RESULTS

The pretreatment with CORM-3 significantly improved the liver histology and the survival rate of mice compared with the controls; CORM-3 also decreased the levels of ALT, AST and TBiL. Furthermore, CORM-3 significantly inhibited the increased concentration of pro-inflammatory cytokines (TNF-alpha, IL-6 and IL-1beta) and increased the anti-inflammatory cytokine (IL-10) productions in ALF mice. Moreover, CORM-3 significantly reduced the increased expression of iNOS and TLR4 in liver tissues and inhibited the nuclear expression of NF-kappaB-p65. CORM-3 had no effect on the increased expression of COX-2 in the ALF mice. An iCORM-3 failed to prevent acute liver damage induced by LPS/D-GalN.

CONCLUSION

These findings provided evidence that CORM-3 may offer a novel alternative approach for the management of ALF through anti-inflammatory functions.

Pdcd4 deficiency enhances macrophage lipoautophagy and attenuates foam cell formation and atherosclerosis in mice

Macrophage foam cells, a major component of the atherosclerotic lesion, have vital roles in the development of atherosclerosis. Lipoautophagy, a type of autophagy characterized by selective delivery of lipid droplet for lysosomal degradation, may impact atherosclerosis by regulating macrophage foam cell formation. Previously, we reported that programmed cell death 4 (PDCD4), a tumor suppressor, negatively regulated autophagy in tumor cells. However, its roles in macrophage lipoautophagy, foam cell formation and atherosclerosis remain to be established. Here we found that Pdcd4 deficiency clearly improved oxidized low-density lipoproteins-impaired autophagy efflux, promoted autophagy-mediated lipid breakdown in murine macrophages and thus prevented macrophage conversion into foam cells. Importantly, Pdcd4 deficiency in mice significantly upregulated macrophage autophagy in local plaques along with attenuated lipid accumulation and atherosclerotic lesions in high-fat-fed Apolipoprotein E knockout mice. Bone marrow transplantation experiment demonstrated that PDCD4-mediated autophagy in hematopoietic cells contributed to the development of atherosclerosis. These results indicate that endogenous PDCD4 promotes for macrophage foam cell formation and atherosclerosis development via inhibiting autophagy and provides new insights into atherogenesis, suggesting that promoting macrophage autophagy through downregulating PDCD4 expression may be beneficial for treating atherosclerosis.

Recql5 protects against lipopolysaccharide/D-galactosamine-induced liver injury in mice

AIM: To investigate the effects of Recql5 deficiency on liver injury induced by lipopolysaccharide/D-galactosamine (LPS/D-Gal).

METHODS: Liver injury was induced in wild type (WT) or Recql5-deficient mice using LPS/D-Gal, and assessed by histological, serum transaminases, and mortality analyses. Hepatocellular apoptosis was quantified by transferase dUTP nick end labeling assay and Western blot analysis of cleaved caspase-3. Liver inflammatory chemokine and cytochrome P450 expression was analyzed by quantitative reverse transcription-PCR. Neutrophil infiltration was evaluated by myeloperoxidase activity. Expression and phosphorylation of ERK, JNK, p65, and H2A.X was determined by Western blot. Oxidative stress was evaluated by measuring malondialdehyde production and nitric oxide synthase, superoxide dismutase, glutathione peroxidase, catalase, and glutathione reductase activity.

RESULTS: Following LPS/D-Gal exposure, Recql5-deficient mice exhibited enhanced liver injury, as evidenced by more severe hepatic hemorrhage, higher serum aspartate transaminase and alanine transaminase levels, and lower survival rate. As compared to WT mice, Recql5-deficient mice showed an increased number of apoptotic hepatocytes and higher cleaved caspase-3 levels. Recql5-deficient mice exhibited increased DNA damage, as evidenced by increased γ-H2A.X levels. Inflammatory cytokine levels, neutrophil infiltration, and ERK phosphorylation were also significantly increased in the knockout mice. Additionally, Recql5-deficicent mice exhibited increased malondialdehyde production and elevated inducible nitric oxide synthase, superoxide dismutase, glutathione peroxidase, catalase, and glutathione reductase activity, indicative of enhanced oxidative stress. Moreover, CYP450 expression was significantly downregulated in Recql5-deficient mice after LPS/D-Gal treatment.

CONCLUSION: Recql5 protects the liver against LPS/D-Gal-induced injury through suppression of hepatocyte apoptosis and oxidative stress and modulation of CYP450 expression.

Deficiency of programmed cell death 4 results in increased IL-10 expression by macrophages and thereby attenuates atherosclerosis in hyperlipidemic mice

Programmed cell death 4 (Pdcd4) is a newly defined inhibitor of transcription and translation and a tumor suppressor. Recent studies have suggested that Pdcd4 may also be involved in some inflammatory diseases. However, its role in atherosclerosis, a chronic inflammation of the arterial wall, remains to be investigated. Here, we found that Pdcd4 deficiency in mice increased the expression of IL-10 in macrophages and decreased the expression of IL-17 in T cells in the presence of an atherosclerosis-associated stimulator in vitro and in high fat-induced atherosclerotic plaques. Importantly, knocking out Pdcd4 led to a decrease in atherosclerotic lesions in Apoe(-/-) mice fed a high fat diet. This effect could be partly reversed by blocking IL-10 with a neutralizing antibody but not by the application of exogenous IL-17. Further mechanistic studies revealed that Pdcd4 negatively regulated the expression of IL-10 in an ERK1/2- and p38-dependent manner. These results demonstrate that Pdcd4 deficiency attenuates atherosclerosis in hyperlipidemic mice in part through the upregulation of the anti-inflammatory cytokine IL-10. This indicates that endogenous Pdcd4 promotes atherosclerosis and therefore represents a potential therapeutic target for patients with atherosclerosis.