Lipopolysaccharide downregulates the expression of p53 through activation of MDM2 and enhances activation of nuclear factor-kappa B

Integrating Network Pharmacology and Experimental Validation to Decipher the Anti-Inflammatory Effects of Magnolol on LPS-induced RAW264.7 Cells

INTRODUCTION

Magnolol is beneficial against inflammation-mediated damage. However, the underlying mechanisms by which magnolol exerts anti-inflammatory effects on macrophages remain unclear.

OBJECTIVE

In this study, network pharmacology and experimental validation were used to assess the effect of magnolol on inflammation caused by lipopolysaccharide (LPS) in RAW264.7 cells.

MATERIALS AND METHODS

Genes related to magnolol were identified in the PubChem and Swiss Target Prediction databases, and gene information about macrophage polarization was retrieved from the GeneCards, OMIM, and PharmGKB databases. Analysis of protein-protein interactions was performed with STRING, and Cytoscape was used to construct a component-target-disease network. GO and KEGG enrichment analyses were performed to ascertain significant molecular biological processes and signaling pathways. LPS was used to construct the inflammatory cell model. ELISA and qRT.PCR were used to examine the expression levels of inflammationassociated factors, immunofluorescence was used to examine macrophage markers (CD86 and CD206), and western blotting was used to examine protein expression levels.

RESULTS

The hub target genes of magnolol that act on macrophage polarization were MDM2, MMP9, IL-6, TNF, EGFR, AKT1, and ERBB2. The experimental validation results showed that magnolol treatment decreased the levels of proinflammatory factors (TNF-α, IL-1β, and IL-6). Moreover, the levels of anti-inflammatory factors (IL-10 and IL-4) were increased. In addition, magnolol upregulated the expression of M2 markers (Agr-1, Fizzl, and CD206) and downregulated M1 markers (CD86). The cell experiment results supported the network pharmacological results and demonstrated that magnolol alleviated inflammation by modulating the PI3k-Akt and P62/keap1/Nrf2 signaling pathways.

CONCLUSION

According to network pharmacology and experimental validation, magnolol attenuated inflammation in LPS-induced RAW264.7 cells mainly by inhibiting M1 polarization and enhancing M2 polarization by activating the PI3K/Akt and P62/keap1/Nrf2 signaling pathways.

A novel ferritin L (FerL) in hybrid crucian carp could participate in host defense against Aeromonas hydrophila infection and diminish inflammatory signals

FerL, a multifunctional iron-storage polypeptide, not only exhibited a regulatory role in iron metabolism, but also participated in the regulation of fish immunity. In this study, ORF sequence of WR-FerL was 522 bp, encoding 173 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-FerL was detected in spleen. A. hydrophila challenge and LPS stimulation could sharply enhance WR-FerL mRNA expression in tissues and fish cells, respectively. Purified WR-FerL fusion peptide exhibited in vitro binding activity to A. hydrophila and endotoxin, limited bacterial dissemination to tissues as well as attenuated A. hydrophila-induced production of pro-inflammatory cytokines. Moreover, WR-FerL overexpression could abrogate NF-κB and TNFα promoter activity in fish cells. These results indicated that WR-FerL could play an important role in host defense against A. hydrophila infection.

Chimeric ferritin H in hybrid crucian carp exhibits a similar down-regulation in lipopolysaccharide-induced NF-κB inflammatory signal in comparison with Carassius cuvieri and Carassius auratus red var

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs. A sharp increase of ferritin H mRNA was observed in RCCFCs, WCCFCs and WRFCs following lipopolysaccharide (LPS) challenge. Overexpression of RCC/WCC/WR-ferritin H can decrease MyD88-IRAK4 signal and antagonize NF-κB, TNFα promoter activity in RCCFCs, WCCFCs and WRFCs, respectively. These results indicated that ferritin H in hybrid offspring harbors highly-conserved domains with a close sequence similarity to those of its parents, playing a regulatory role in inflammatory signals.

In Vivo Validation of Alternative FDXR Transcripts in Human Blood in Response to Ionizing Radiation

Following cell stress such as ionising radiation (IR) exposure, multiple cellular pathways are activated. We recently demonstrated that ferredoxin reductase (FDXR) has a remarkable IR-induced transcriptional responsiveness in blood. Here, we provided a first comprehensive FDXR variant profile following DNA damage. First, specific quantitative real-time polymerase chain reaction (qPCR) primers were designed to establish dose-responses for eight curated FDXR variants, all up-regulated after IR in a dose-dependent manner. The potential role of gender on the expression of these variants was tested, and neither the variants response to IR nor the background level of expression was profoundly affected; moreover, in vitro induction of inflammation temporarily counteracted IR response early after exposure. Importantly, transcriptional up-regulation of these variants was further confirmed in vivo in blood of radiotherapy patients. Full-length nanopore sequencing was performed to identify other FDXR variants and revealed the high responsiveness of FDXR-201 and FDXR-208. Moreover, FDXR-218 and FDXR-219 showed no detectable endogenous expression, but a clear detection after IR. Overall, we characterised 14 FDXR transcript variants and identified for the first time their response to DNA damage in vivo. Future studies are required to unravel the function of these splicing variants, but they already represent a new class of radiation exposure biomarkers.

Combination of genetic polymorphisms in TLR influence cytokine profile in HCV patients treated with DAAs in the State of Amazonas

Hepatitis C is a public health problem and affects approximately 3% of the world's population. HCV infections have a wide spectrum of clinical manifestations, and several single nucleotide polymorphisms (SNPs) in the genes of the toll-like receptors are cited to influence the clinical outcomes. A cross-sectional study was conducted in the Amazonas State, Brazil in which SNPs in TLR4 and TLR9 genes were genotyped by PCR-RFLP in 151 HCV chronic liver disease patients and 206 healthy donors. The circulating cytokines IL-6, TNF, IL-10, IL-2, IFN-γ, IL-4 and IL-17A were measured by cytometric bead array (CBA) which revealed that the combined genotypes of TLR9 -1237T/T and -1486C/T seem to influence the cytokine profile under lipopolysaccharide (LPS) stimulation of the Th17 profile, especially among patients with advanced chronic liver disease when treated with DAAs.

TSLP Exacerbates Septic Inflammation via Murine Double Minute 2 (MDM2) Signaling Pathway

Thymic stromal lymphopoietin (TSLP) is crucial for Th2-mediated inflammation. Sepsis is a serious systemic inflammatory reaction with organ dysfunction by infection. However, the function of TSLP during sepsis is poorly understood. Thus, we investigated a role and regulatory mechanism of TSLP during sepsis. Sepsis was induced by lipopolysaccharides (LPS) or Escherichia coli DH5α injection in mice. TSLP levels were measured in human subjects, mice, and macrophages. TSLP deficiency or murine double minute 2 (MDM2) deficiency was induced using siRNA or an MDM2 inhibitor, nutlin-3a. We found that TSLP levels were elevated in serum of patients and mice with sepsis. TSLP deficiency lowered liver damage and inflammatory cytokine levels in mice with sepsis. TSLP was produced by the MDM2/NF-κB signaling pathway in LPS-stimulated macrophages. TSLP downregulation by an MDM2 inhibitor, nutlin-3a, alleviated clinical symptoms and septic inflammatory responses. Pharmacological inhibition of TSLP level by cisplatin reduced the septic inflammatory responses. Altogether, the present results show that TSLP exacerbates septic inflammation via the MDM2 signaling pathway, suggesting that TSLP may be a potential target for the treatment of sepsis.

Sparstolonin B (SsnB) attenuates liver fibrosis via a parallel conjugate pathway involving P53-P21 axis, TGF-beta signaling and focal adhesion that is TLR4 dependent

SsnB previously showed a promising role to lessen liver inflammation observed in a mouse model of NAFLD. Since NAFLD can progress to fibrosis, studies were designed to unravel its role in attenuating NAFLD associated fibrosis. Using both in vivo and in vitro approaches, the study probed the possible mechanisms that underlined the role of SsnB in mitigating fibrosis. Mechanistically, SsnB, a TLR4 antagonist, decreased TLR4-PI3k akt signaling by upregulating PTEN protein expression. It also decreased MDM2 protein activation and increased p53 and p21 gene and protein expression. SsnB also downregulated pro-fibrogenic hedgehog signaling pathway, inhibited hepatic stellate cell proliferation and induced apoptosis in hepatic stellate cells, a mechanism that was LPS dependent. Further, SsnB decreased fibrosis by antagonizing TLR4 induced TGFβ signaling pathway. Alternatively, SsnB augmented BAMBI (a TGFβ pseudo-receptor) expression in mice liver by inhibiting TLR4 signaling pathway and thus reduced TGFβ signaling, resulting in decreased hepatic stellate cell activation and extracellular matrix deposition. In vitro experiments on human hepatic stellate cell line showed that SsnB increased gene and protein expression of BAMBI. It also decreased nuclear co-localization of phospho SMAD2/3 and SMAD4 protein and thus attenuated TGFβ signaling in vitro. We also observed a significant decrease in phosphorylation of SMAD2/3 protein, decreased STAT3 activation, alteration of focal adhesion protein and stress fiber disassembly upon SsnB administration in hepatic stellate cells which further confirmed the antagonistic effect of SsnB on TLR4-induced fibrogenesis.

Influence of Confounding Factors on Radiation Dose Estimation Using In Vivo Validated Transcriptional Biomarkers

For triage purposes following a nuclear accident, blood-based gene expression biomarkers can provide rapid dose estimates for a large number of individuals. Ionizing-radiation-responsive genes are regulated through the DNA damage-response pathway, which includes activation of multiple transcription factors. Modulators of this pathway could potentially affect the response of these biomarkers and consequently compromise accurate dose estimation calculations. In the present study, four potential confounding factors were selected: cancer condition, sex, simulated bacterial infection (lipopolysaccharide), and curcumin, an anti-inflammatory/antioxidant agent. Their potential influence on the transcriptional response to radiation of the genes CCNG1 and PHPT1, two biomarkers of radiation exposure ex vivo, was assessed. First, both CCNG1 and PHPT1 were detected in vivo in blood samples from radiotherapy patients and as such were validated as biomarkers of exposure. Importantly, their basal expression level was slightly but significantly affected in vivo by patients' cancer condition. Moreover, lipopolysaccharide stimulation of blood irradiated ex vivo led to a significant modification of CCNG1 and PHPT1 transcriptional response in a dose- and time-dependent manner with opposite regulatory effects. Curcumin also affected CCNG1 and PHPT1 transcriptional response counteracting some of the radiation induction. No differences were observed based on sex. Dose estimations calculated using linear regression were affected by lipopolysaccharide and curcumin. In conclusion, several confounding factors tested in this study can indeed modulate the transcriptional response of CCNG1 and PHPT1 and consequently can affect radiation exposure dose estimations but not to a level which should prevent the biomarkers' use for triage purposes.

Cellular and behavioral effects of lipopolysaccharide treatment are dependent upon neurokinin-1 receptor activation

Background

Several psychiatric conditions are affected by neuroinflammation and neuroimmune activation. The transcription factor nuclear factor kappa light-chain-enhancer of activated B cells (NFkB) plays a major role in inflammation and innate immunity. The neurokinin-1 receptor (NK1R) is the primary endogenous target of the neuroactive peptide substance P, and some data suggests that NK1R stimulation may influence NFkB activity. Both NK1R and NFkB have been shown to play a functional role in complex behaviors including stress responsivity, depression, and addiction. In this study, we test whether NFkB activity in the brain (stimulated by lipopolysaccharide administration) is dependent upon the NK1R.

Methods

Adult male Wistar rats were treated systemically with the NK1R antagonist L822429 followed by administration of systemic lipopolysaccharide (LPS, a strong activator of NFkB). Hippocampal extracts were used to assess expression of proinflammatory cytokines and NFkB-DNA-binding potential. For behavioral studies, rats were trained to consume 1% (w/v) sucrose solution in a continuous access two-bottle choice model. After establishment of baseline, animals were treated with L822429 and LPS and sucrose preference was measured 12 h post-treatment.

Results

Systemic LPS treatment causes a significant increase in proinflammatory cytokine expression and NFkB-DNA-binding activity within the hippocampus. These increases are attenuated by systemic pretreatment with the NK1R antagonist L822429. Systemic LPS treatment also led to the development of anhedonic-like behavior, evidenced by decreased sucrose intake in the sucrose preference test. This behavior was significantly attenuated by systemic pretreatment with the NK1R antagonist L822429.

Conclusions

Systemic LPS treatment induced significant increases in NFkB activity, evidenced by increased NFkB-DNA binding and by increased proinflammatory cytokine expression in the hippocampus. LPS also induced anhedonic-like behavior. Both the molecular and behavioral effects of LPS treatment were significantly attenuated by systemic NK1R antagonism, suggesting that NK1R stimulation lies upstream of NFkB activation following systemic LPS administration and is at least in part responsible for NFkB activation.

P53 modulates hepatic insulin sensitivity through NF-κB and p38/ERK MAPK pathways

Besides its well-established oncosuppressor activity, the role of p53 in regulating metabolic pathways has been recently identified. Nevertheless, the function of p53 with respect to insulin resistance appears highly controversial. To address this issue, we investigated the expression of p53 in experimental model of insulin resistance. Then we used activator (nutlin-3α) and inhibitor (pifithrin-α, PFT-α) of p53 in HepG2 cell. Here we showed that p53 protein level was decreased in the hepatic tissue of high-fat diet-induced insulin resistance mice, genetically diabetic ob/ob mice and palmitate (PA) treated HepG2 cells. And high expression of phosphor-p38, ERK1/2 and nuclear factor kappa B (NF-κB) p65 accompanied with low expression of p53. But activation of p53 with nutlin-3α prevented PA-induced reduction of glucose consumption and suppression of insulin signaling pathways. At the same time, nutlin-3α downregulated the activation of NF-κB, p38 and ERK1/2 pathways upon stimulation with PA. In contrast, inhibition of p53 with PFT-α decreased glucose consumption and suppressed insulin signaling pathway. Furthermore, PFT-α activated NF-κB, p38 and ERK1/2 pathways in HepG2 cells. Overall, these results suggest that p53 is involved in improving insulin sensitivity of hepatic cells via inhibition of mitogen-activated protein kinases (MAPKs) and NF-κB pathways.

Co‑expression of murine double minute 2 siRNA and wild‑type p53 induces G1 cell cycle arrest in H1299 cells

The therapeutic options available for the treatment of advanced non-small cell lung cancer have increased over the past decade. Small molecule gene therapy has emerged as an effective therapy for the treatment of lung cancer in vitro and in vivo although it has not been tested in a clinical setting. In particular, therapies that target the negative feedback loop between p53 and murine double minute 2 (MDM2) provide a favorable outcome by maintaining activation of the tumor suppressor gene p53. The present study used transfection to simultaneously knockdown MDM2 expression using small interfering (si)RNA, and overexpress wild‑type p53 in H1299 cells. The effects of transfection on cell proliferation and cell cycle progression were determined using an MTT assay and flow cytometry, and the effects on mRNA and protein expression were determined by western blotting and reverse transcription polymerase chain reaction. The results indicated that simultaneously knocking down MDM2 and overexpressing p53 was able to inhibit proliferation and induce G1 cell cycle arrest in H1299 cells, compared with either alone. These findings indicated that the si‑MDM2‑p53 co‑expression plasmid may induce cell cycle arrest, and may be considered a novel therapeutic option for the treatment of lung cancer.

Molecular cloning and characterization of PTEN in the orange-spotted grouper (Epinephelus coioides)

PTEN is a key tumor suppressor gene that can play a regulatory role in the cellular proliferation, survival and apoptosis. In this study, the full-length PTEN (EcPTEN) was obtained, containing a 5'UTR of 745 bp, an ORF of 1269 bp and a 3'UTR of 106 bp. The EcPTEN gene encoded a polypeptide of 422 amino acids with an estimated molecular mass of 49.14 KDa and a predicted isoelectric point (pI) of 6.34. The deduced amino acid sequence analysis showed that EcPTEN comprised the conserved residues and the characteristic domains known to the critical functionality of PTEN. qRT-PCR analysis revealed that EcPTEN mRNA was broadly expressed in all the examined tissues, while the highest expression level was observed in liver, followed by the expression in blood, kidney, spleen, heart, gill, muscle and intestine. The groupers challenged with Vibrio alginolyticus showed a sharp increase of EcPTEN mRNA expression in immune tissues. In addition, western blotting analysis confirmed that the up-regulation of EcPTEN protein expression was steadily induced in liver. Subcellular localization analysis indicated that EcPTEN was localized in both nucleus and cytoplasm. Overexpression of EcPTEN can activate the apoptotic cascade and abrogate NF-kB, AP-1, Stat3 and Myc promoter activity in Hela cells. These results indicated that EcPTEN harboring highly-conserved domains with a close sequence similarity to those of PTP superfamily may disrupt the mammalian signalings and play a regulatory role in the apoptotic process.

Molecular cloning, characterization and expression analysis of (B-cell lymphoma-2 associated X protein) Bax in the orange-spotted grouper (Epinephelus coioides) after the Vibrio alginolyticus challenge

Bax is a pro-apoptotic member of Bcl-2 like superfamily, playing an important role in regulating the apoptosis. In this study, the full-length Bax (EcBax) was obtained, containing a 5'UTR of 64 bp, an ORF of 579 bp and a 3'UTR of 1021 bp. The EcBax gene encoded a polypeptide of 192 amino acids with an estimated molecular mass of 21.55 KDa and a predicted isoelectric point (pI) of 6.75. The deduced amino acid sequence analysis showed that EcBax comprised the conserved residues and the characteristic domains known to the critical function of Bax. qRT-PCR analysis revealed that EcBax mRNA was broadly expressed in all of the examined tissues, while the highest expression level was observed in blood, followed by the expression in liver, gill, spleen, kidney, heart, muscle and intestine. A sharp increase of EcBax expression was observed in the vibrio challenge group by comparing with those in the control. Subcellular localization analysis revealed that EcBax was predominantly localized in the cytoplasm. EcBax exerted a regulatory role in modulating the mitochondrial membrane potential, promoting the cytochrome c release, and then activating the downstream caspase signaling. Moreover, the overexpression of EcBax can decrease the cell viability and antagonize NF-kB, AP-1, Stat3 promoter activity in Hela cells. These results indicate that EcBax containing the conserved domain of pro-apoptotic member of Bcl-2 family may disrupt the mammalian signaling and play a regulative role in the apoptotic process.