Both intrinsic and extrinsic apoptotic pathways are involved in Toll-like receptor 4 (TLR4)-induced cell death in monocytic THP-1 cells

Okadaic acid enhances NfKB, TLR-4, caspase 3, ERK ½, c-FOS, and 8-OHdG signaling pathways activation in brain tissues of zebrafish larvae

This study was designed to investigate the potential neuronal damage mechanism of the okadaic acid (OA) in the brain tissues of zebrafish embryos by evaluating in terms of immunofluorescence of Nf KB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG signaling pathways. We also evaluated body malformations. For this purpose, zebrafish embryos were exposed to 0.5 μg/ml, 1 μg/ml and 2.5 μg/ml of OA for 5 days. After application, FITC/GFP labeled protein-specific antibodies were used in immunofluorescence assay for NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG respectively. The results indicated that OA caused immunofluorescence positivity of NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG in a dose-dependent manner in the brain tissues of zebrafish embryos. Pericardial edema (PE), nutrient sac edema (YSE) and body malformations, tail malformation, short tail and head malformation (BM) were detected in zebrafish embryos. These results suggest that OA induces neuronal damage by affecting the modulation of DNA damage, apoptotic, and inflammatory activities in the brain tissues of zebrafish embryos. The increase in signaling pathways shows that OA can cause damage in the structure and function of brain nerve cells. Our results provide a new basis for the comprehensive assessment of the neural damage of OA and will offer enable us to better understand molecular the mechanisms underlying the pathophysiology of OA toxicity.

Harnessing innate immune pathways for therapeutic advancement in cancer

The innate immune pathway is receiving increasing attention in cancer therapy. This pathway is ubiquitous across various cell types, not only in innate immune cells but also in adaptive immune cells, tumor cells, and stromal cells. Agonists targeting the innate immune pathway have shown profound changes in the tumor microenvironment (TME) and improved tumor prognosis in preclinical studies. However, to date, the clinical success of drugs targeting the innate immune pathway remains limited. Interestingly, recent studies have shown that activation of the innate immune pathway can paradoxically promote tumor progression. The uncertainty surrounding the therapeutic effectiveness of targeted drugs for the innate immune pathway is a critical issue that needs immediate investigation. In this review, we observe that the role of the innate immune pathway demonstrates heterogeneity, linked to the tumor development stage, pathway status, and specific cell types. We propose that within the TME, the innate immune pathway exhibits multidimensional diversity. This diversity is fundamentally rooted in cellular heterogeneity and is manifested as a variety of signaling networks. The pro-tumor effect of innate immune pathway activation essentially reflects the suppression of classical pathways and the activation of potential pro-tumor alternative pathways. Refining our understanding of the tumor's innate immune pathway network and employing appropriate targeting strategies can enhance our ability to harness the anti-tumor potential of the innate immune pathway and ultimately bridge the gap from preclinical to clinical application.

Harnessing the innate immune system by revolutionizing macrophage-mediated cancer immunotherapy

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fastgrowing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy.

Acute exposure to gold nanoparticles aggravates lipopolysaccharide-induced liver injury by amplifying apoptosis via ROS-mediated macrophage-hepatocyte crosstalk

Background

Gold nanoparticles (AuNPs) are increasingly utilized in industrial and biomedical fields, thereby demanding a more comprehensive knowledge about their safety. Current toxicological studies mainly focus on the unfavorable biological impact governed by the physicochemical properties of AuNPs, yet the consequences of their interplay with other bioactive compounds in biological systems are poorly understood.

Results

In this study, AuNPs with a size of 10 nm, the most favorable size for interaction with host cells, were given alone or in combination with bacterial lipopolysaccharide (LPS) in mice or cultured hepatic cells. The results demonstrated that co exposure to AuNPs and LPS exacerbated fatal acute liver injury (ALI) in mice, although AuNPs are apparently non-toxic when administered alone. AuNPs do not enhance systemic or hepatic inflammation but synergize with LPS to upregulate hepatic apoptosis by augmenting macrophage-hepatocyte crosstalk. Mechanistically, AuNPs and LPS coordinate to upregulate NADPH oxidase 2 (NOX2)-dependent reactive oxygen species (ROS) generation and activate the intrinsic apoptotic pathway in hepatic macrophages. Extracellular ROS generation from macrophages is then augmented, thereby inducing calcium-dependent ROS generation and promoting apoptosis in hepatocytes. Furthermore, AuNPs and LPS upregulate scavenger receptor A expression in macrophages and thus increase AuNP uptake to mediate further apoptosis induction.

Conclusions

This study reveals a profound impact of AuNPs in aggravating the hepatotoxic effect of LPS by amplifying ROS-dependent crosstalk in hepatic macrophages and hepatocytes.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01203-w.

Protein Adsorption on Surfaces Functionalized with COOH Groups Promotes Anti-inflammatory Macrophage Responses

Implants can induce a foreign body reaction that leads to chronic inflammation and fibrosis in the surrounding tissue. Macrophages help detect the foreign material, play a role in the inflammatory response, and may promote fibrosis instead of the desired tissue regeneration around implants. Implant surface properties impact macrophage responses by changing the nature of the adsorbed protein layer, but conflicting studies highlight the complexity of this relationship. In this study, the effect of surface chemistry on macrophage behavior was investigated with poly(styrene) surfaces containing common functional groups at similar surface densities. The protein layer was characterized to identify the proteins that adsorbed on the surfaces from the medium and the proteins secreted onto the surfaces by adherent macrophages. Of the surface chemistries studied, carboxylic acid (COOH) groups promoted anti-inflammatory responses from unstimulated macrophages and did not exacerbate inflammation upon stimulation. These surfaces also enhanced the adsorption of proteins involved in integrin signaling and promoted the secretion of proteins related to angiogenesis, integrin signaling, and cytokine signaling, which have been previously associated with improved biomaterial integration. Therefore, this study suggests that surface modification with COOH groups may help improve the integration of implants in the body by enhancing anti-inflammatory macrophage responses through altered protein adsorption.

Impedimetric Microfluidic Sensor-in-a-Tube for Label-Free Immune Cell Analysis

Analytical platforms based on impedance spectroscopy are promising for non-invasive and label-free analysis of single cells as well as of their extracellular matrix, being essential to understand cell function in the presence of certain diseases. Here, an innovative rolled-up impedimetric microfulidic sensor, called sensor-in-a-tube, is introduced for the simultaneous analysis of single human monocytes CD14+ and their extracellular medium upon liposaccharides (LPS)-mediated activation. In particular, rolled-up platinum microelectrodes are integrated within for the static and dynamic (in-flow) detection of cells and their surrounding medium (containing expressed cytokines) over an excitation frequency range from 10² to 5 × 10⁶  Hz. The correspondence between cell activation stages and the electrical properties of the cell surrounding medium have been detected by electrical impedance spectroscopy in dynamic mode without employing electrode surface functionalization or labeling. The designed sensor-in-a-tube platform is shown as a sensitive and reliable tool for precise single cell analysis toward immune-deficient diseases diagnosis.

Asiaticoside ameliorates acinar cell necrosis in acute pancreatitis via toll-like receptor 4 pathway

Acinar cell necrosis is one of the most prominent pathophysiological changes of acute pancreatitis (AP). Asiaticoside (AS) is a triterpene compound with confirmed apoptosis-and necrosis-related activities. However, the specific effects of AS on AP have not been determined. In this study, we aimed to investigate the protective effect of AS on AP using two mouse models. In the caerulein-induced mild acute pancreatitis (MAP) model, We found that AS administration reduced serum amylase levels and alleviated the histopathological manifestations of pancreatic tissue in a dose-dependent manner. And the levels of toll-like receptor 4 (TLR4) and necrotic related proteins (RIP3 and p-MLKL) of pancreatic tissue were reduced after AS administration. In addition, TLR4 deficiency eliminated the protective effect of AS on AP induced by caerulein in mice. Correspondingly, we elucidated the effect of AS in vitro and found that AS protected against pancreatic acinar cells necrosis and TAK-242 counteracted this protective effect. Meanwhile, we found that AS ameliorated the severity of pancreatic tissue injury and pancreatitis-associated lung injury in a severe acute pancreatitis model induced by l-arginine. Furthermore, Molecular docking results revealed interaction between AS and TLR4. Taken together, our data for the first time confirmed the protective effects of AS on AP in mice via TLR4 pathway.

Toll-like receptor 4 is a therapeutic target for prevention and treatment of liver failure

BACKGROUND & AIMS

Toll-like receptor 4 (TLR4) plays an essential role in mediating organ injury in acute liver failure (ALF) and acute-on-chronic liver failure (ACLF). Herein, we assess whether inhibiting TLR4 signaling can ameliorate liver failure and serve as a potential treatment.

METHODS

Circulating TLR4 ligands and hepatic TLR4 expression were measured in plasma samples and liver biopsies from patients with cirrhosis. TAK-242 (TLR4 inhibitor) was tested in vivo (10 mg/kg intraperitoneally) in rodent models of ACLF (bile duct ligation + lipopolysaccharide [LPS]; carbon tetrachloride + LPS) and ALF (galactosamine + LPS) and in vitro on immortalized human monocytes (THP-1) and hepatocytes (HHL5). The in vivo therapeutic effect was assessed by coma-free survival, organ injury and cytokine release and in vitro by measuring IL-6, IL-1β or cell injury (TUNEL), respectively.

RESULTS

In patients with cirrhosis, hepatic TLR4 expression was upregulated and circulating TLR4 ligands were increased (p <0.001). ACLF in rodents was associated with a switch from apoptotic cell death in ALF to non-apoptotic forms of cell death. TAK-242 reduced LPS-induced cytokine secretion and cell death (p = 0.002) in hepatocytes and monocytes in vitro. In rodent models of ACLF, TAK-242 administration improved coma-free survival, reduced the degree of hepatocyte cell death in the liver (p <0.001) and kidneys (p = 0.048) and reduced circulating cytokine levels (IL-1β, p <0.001). In a rodent model of ALF, TAK-242 prevented organ injury (p <0.001) and systemic inflammation (IL-1β, p <0.001).

CONCLUSION

This study shows that TLR4 signaling is a key factor in the development of both ACLF and ALF; its inhibition reduces the severity of organ injury and improves outcome. TAK-242 may be of therapeutic relevance in patients with liver failure.

LAY SUMMARY

Toll-like receptor 4 (or TLR4) mediates endotoxin-induced tissue injury in liver failure and cirrhosis. This receptor sensitizes cells to endotoxins, which are produced by gram-negative bacteria. Thus, inhibiting TLR4 signaling with an inhibitor (TAK-242) ameliorates organ injury and systemic inflammation in rodent models of acute and acute-on-chronic liver failure.

Distinct anti-proliferative effects of herbal melanin on human acute monocytic leukemia THP-1 cells and embryonic kidney HEK293 cells

BACKGROUND

Herbal melanin (HM) is a dark pigment extracted from the seed coat of Nigella sativa L. and known to exert biological effects via toll-like receptor 4 (TLR4). Recently, TLR4 was described as involved in natural programmed cell death (apoptosis). Tumor and embryonic cells are used as in vitro cellular models for drug and anti-cancer agent screening. To date, no cytotoxic studies have been reported of HM in TLR4-positive acute monocytic leukemia THP-1 cells compared to TLR4-negative human embryonic kidney HEK293 cells.

METHODS

We studied the anti-proliferative effects of several HM concentrations on THP-1 and HEK293 cells by evaluating cell viability using the CellTiter-Glo® luminescent assay, assessing the TLR4 expression level, determining the apoptotic status, and analyzing the cell cycle distribution using flow cytometry. Apoptotic pathways were investigated using mitochondrial transition pore opening, caspase activity assays and immunoblot technology.

RESULTS

Low HM concentrations did not affect THP-1 cell viability, but high HM concentrations (62.5-500 μg/mL) did decrease THP-1 cell viability and induced G0/G1 phase cell cycle arrest. Only at the highest concentration (500 μg/mL), HM slightly increased the TLR4 expression on the THP-1 cell surface, concomitantly upregulated TLR4 whole protein and gene expression, and induced apoptosis in THP-1 cells via activation of the extrinsic and intrinsic pathways. No change of apoptotic status was noticed in TLR4-negative HEK293 cells, although HM decreased HEK293 cell viability and induced cell growth arrest in the G2 phase.

CONCLUSION

HM exerts distinct anti-proliferative effects on human acute monocytic leukemia and embryonic kidney cells mainly through cell cycle interference in a TLR4-independent manner and through apoptosis induction in a TLR4-dependent manner, as observed in only the THP-1 cells.

Inhibiting pannexin-1 alleviates sepsis-induced acute kidney injury via decreasing NLRP3 inflammasome activation and cell apoptosis

AIMS

Sepsis-induced acute kidney injury (SI-AKI) is the fifth most common cause of hospital-acquired acute kidney injury. Pannexin1 (Panx1) triggers inflammation and apoptosis which act as crucial factors in the pathogenesis of SI-AKI. We aimed to investigate the expression of Panx1 and its role on the inflammation and apoptosis in SI-AKI.

MATERIALS AND METHODS

SI-AKI model was established by lipopolysaccharide (LPS) injection in mice and LPS-treated HK-2 cells in vitro. Panx1 was inhibited by pretreating with carbenoxolone (CBX) or small interfering RNA in vivo and vitro, respectively. The expression of Panx1 was determined by qPCR, western blot and immunohistochemistry (IHC). Kidney damage was evaluated by kidney function, histopathological examination and AKI biomarkers. Inflammatory cytokines were detected by qPCR and ELISA. Apoptosis was detected by TUNEL staining and the expression of apoptosis-related proteins. The activation of nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome was measured by western blot.

KEY FINDINGS

Panx1 increased in LPS-induced SI-AKI mice and HK-2 cells, as well as in SI-AKI patients. CBX alleviated the renal function and pathological damage, as well as decreased the mRNA of kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL). Inhibiting Panx1 decreased the production of IL-1β, IL-6 and TNF-α, as well as tubular cell apoptosis in SI-AKI. Inhibiting Panx1 suppressed inflammatory cytokines and apoptosis via inhibiting NLRP3 inflammasome activation and regulating apoptotic protein Bax and Bcl2 expression, respectively.

SIGNIFICANCE

These observations suggest that pharmacological inhibition of Panx1 might be a potential approach in the clinical therapy of SI-AKI.

Herbal melanin inhibits colorectal cancer cell proliferation by altering redox balance, inducing apoptosis, and modulating MAPK signaling

Background

Colorectal carcinoma is one of the most deadly cancers that requests effective and safe chemotherapy. Evaluation of natural product-based anticancer drugs as adjuvant treatment with fewer side effects is largely unexplored research fields. Herbal melanin (HM) is an extract of the seed coats of Nigella sativa that modulates an inflammatory response through toll-like receptor 4 (TLR4). This TLR4 receptor is also involved in the modulation of apoptosis. We therefore explored the anticancer potential of HM and specifically its effect on the molecular mechanisms underlying adenocarcinoma and metastatic colorectal cancer (mCRC) cell death in vitro.

Methods

Cell viability was evaluated using the MTT assay. Cellular reactive oxygen species (ROS), glutathione levels, and apoptotic status were assessed using fluorometric and colorimetric detection methods. HM-induced apoptotic and other signaling pathways were investigated using Western blot technology and mitochondrial transition pore assay kit. TLR4 receptor downregulation and blockade were performed using siRNA technology and neutralizing antibody, respectively.

Results

Our results showed that HM inhibited the proliferation of the colorectal adenocarcinoma HT29 and mCRC SW620 cell lines. Furthermore, HM enhanced ROS production and decreased glutathione levels. HM-induced apoptosis was associated with mitochondrial outer membrane permeability and cytochrome c release, inhibition of the Bcl2 family proteins, and activation of caspase-3/-7. In addition, HM modulated MAPK pathways by activating the JNK pathway and by inhibiting ERK phosphorylation. TLR4 receptor downregulation enhanced HM-induced apoptosis while TLR4 receptor blockade partially alleviated HM-inhibited ERK phosphorylation.

Conclusion

Altogether, these findings indicate that HM exerts pro-apoptotic effects and inhibits MAPK pathway through TLR4 in mCRC and colorectal adenocarcinoma cells, suggesting HM as a promising natural-based drug for the treatment of colorectal cancer.

Toll-like Receptor 4 Deficiency Aggravates Airway Hyperresponsiveness and Inflammation by Impairing Neutrophil Apoptosis in a Toluene Diisocyanate-Induced Murine Asthma Model

PURPOSE

Accumulating evidence has suggested that toll-like receptor 4 (TLR4) is critically involved in the pathogenesis of asthma. The aim of this study was to investigate the role of TLR4 in toluene diisocyanate (TDI)-induced allergic airway inflammation.

METHODS

TLR4^-/- and wild-type (WT) C57BL/10J mice were sensitized and challenged with TDI to generate a TDI-induced asthma model. B-cell lymphoma 2 (Bcl-2) inhibitors, ABT-199 (4 mg/kg) and ABT-737 (4 mg/kg), were intranasally given to TDI-exposed TLR4^-/- mice after each challenge.

RESULTS

TDI exposure led to increased airway hyperresponsiveness (AHR), granulocyte flux, bronchial epithelial shedding and extensive submucosal collagen deposition, which were unexpectedly aggravated by TLR4 deficiency. Following TDI challenge, TLR4^-/- mice exhibited down-regulated interleukin-17A and increased colony-stimulating factor 3 in bronchoalveolar lavage fluid (BALF), while WT mice did not. In addition, TLR4 deficiency robustly suppressed the expression of NOD-like receptor family pyrin domain containing 3 and NLR family CARD domain containing 4, decreased caspase-1 activity in TDI-exposed mice, but had no effect on the level of high mobility group box 1 in BALF. Flow cytometry revealed that TDI hampered both neutrophil and eosinophil apoptosis, of which neutrophil apoptosis was further inhibited in TDI-exposed TLR4^-/- mice, with marked up-regulation of Bcl-2. Moreover, inhibition of Bcl-2 with either ABT-199 or ABT-737 significantly alleviated neutrophil recruitment by promoting apoptosis.

CONCLUSIONS

These data indicated that TLR4 deficiency promoted neutrophil infiltration by impairing its apoptosis via up-regulation of Bcl-2, thereby resulting in deteriorated AHR and airway inflammation, which suggests that TLR4 could be a negative regulator of TDI-induced neutrophilic inflammation.

Novel pyridinecarboxaldehyde thiosemicarbazone conjugated magnetite nanoparticulates (MNPs) promote apoptosis in human lung cancer A549 cells

The present study highlights the apoptotic activity of magnetic Fe₃O₄ nanoparticulates functionalized by glutamic acid and 2-pyridinecarboxaldehyde thiosemicarbazone (PTSC) toward human lung epithelial carcinoma A549 cell line. To this aim, the Fe₃O₄ nanoparticulates were prepared using co-precipitation method. Then, the glutamic acid and Fe₃O₄ nanoparticulates were conjugated to each other. The product was further functionalized with bio-reactive PTSC moiety. In addition, the synthesized Fe₃O₄@Glu/PTSC nanoparticulates were characterized by physico-chemical techniques including scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and zeta potential analysis. The effects of in vitro cell viability in Fe3O4@Glu/PTSC nanoparticulate indicated the anti-proliferative properties in a dose-dependent manner (IC₅₀ = 135.6 µM/mL). The high selectivity for tumor cells and far below of activity in HEK293 non-tumorigenic cells is considered as an important feature for this complex (SI, 3.48). Based on the results, PTSC failed to reveal any activity against A549 cells alone. However, Fe₃O₄ nanoparticulates had some effects in inhibiting the growth of lung cancer cell. Furthermore, Bax and Bcl-2 gene expressions were quantified by real-time PCR method. The expression of Bax increased 1.62-fold, while the expression of Bcl-2 decreased 0.76-fold at 135.6 µM/mL concentration of Fe₃O₄@Glu/PTSC compared to untreated A549 cells. Furthermore, the Fe₃O₄@Glu/PTSC nanoparticulate-inducing apoptosis properties were evaluated by Hoechst 33258 staining, Caspase-3 activation assay and Annexin V/propidium iodide staining. The results of the present study suggest that Fe₃O₄@Glu/PTSC nanoparticulates exhibit effective anti-cancer activity against lung cancer cells.

IL-1α and IL-1β promote NOD2-induced immune responses by enhancing MAPK signaling

Both toll-like receptors (TLRs) and nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) induce a tightly regulated inflammatory response at risk of causing tissue damage, depending on the effectiveness of ensuing negative feedback regulatory mechanisms. Cross-regulation between TLRs, NLRs, and cytokine receptors has been observed. However, the cross-regulation between interleukin-1 (IL-1) receptors and NOD2 is not completely understood. In this study, we found that IL-1α/β increased NOD2-induced inflammatory response in human monocytic THP1 cells, peripheral blood mononuclear cells (PBMCs), mouse macrophage RWA264.7 cells and spleen cells, and in an in vivo experiment. IL-1α/β pre-treatment induced the production of CXC chemokines, including growth-regulated oncogene (GRO)-α, GRO-β, and IL-8, and proinflammatory cytokines, including IL-1β, IL-6, and TNFα, which are induced by the activation of NOD2, in a dose- and time-dependent manner. However, pre-treatment with the NOD2 ligand muramyl dipeptide (MDP) did not up-regulate the expression of cytokines induced by IL-1α/β re-treatment. IL-1β treatment increased the expression of A20, which is an important inhibitor of the innate immune response. However, the overexpression of A20 failed to inhibit MDP-induced cytokine production, suggesting that A20 had no effects on the NOD2-induced immune response. In addition, IL-1α/β increased the expression of NOD2 and its downstream adaptor RIP2, and IL-1α/β pre-treatment increased MDP-induced activation of mitogen-activated protein kinases (MAPKs), including ERK, JNK, and P38, which contributed to MDP-induced cytokine production. Based on these results, IL-1α/β promote the NOD2-induced immune responses by enhancing MDP-induced activation of MAPK signaling pathways.

Porcine Beta-Defensin 2 Provides Protection Against Bacterial Infection by a Direct Bactericidal Activity and Alleviates Inflammation via Interference With the TLR4/NF-κB Pathway

Porcine beta-defensin 2 (PBD-2) which is a member of the family of antimicrobial peptides, is widely expressed in pig organs with a broad spectrum of bactericidal activities confirmed in vitro. We previously demonstrated that transgenic (TG) pigs overexpressing PBD-2 could resist the infection by the porcine pathogen Actinobacillus pleuropneumoniae. In this study, the roles of PBD-2 in protecting against bacterial infection were further investigated. The biochemical indexes of the blood sample, body weights, histological morphologies, and weights of the organs of TG mice expressing PBD-2 were measured. Results confirmed that these mice showed normal physiological features. An assay of Salmonella Typhimurium infection was conducted on wild-type (WT) and TG mice. The TG mice possessed higher survival rate, less body weight loss, and pathological changes and smaller recovery rates of bacteria after infection with S. Typhimurium. The in vitro synthetic PBD-2 and the serum and tissue homogenates from the TG mice displayed a direct bactericidal activity. Moreover, PBD-2 could inhibit the release of the proinflammatory cytokines, including IL-6, TNF-α, IL-1β, and IL-12, in the TG mice infected with S. Typhimurium or treated with lipopolysaccharide (LPS). The WT mice treated with PBD-2 and S. Typhimurium or LPS showed reduced levels of proinflammatory cytokines. The mouse macrophage cell line RAW 264.7 which expressed PBD-2 was constructed to detect the signal pathways affected by PBD-2. The suppressing effect of PBD-2 on the release of the proinflammatory cytokines was confirmed using RAW 264.7 either expressing PBD-2 or supplemented with PBD-2. The promoter activity and mRNA level of NF-κB were detected, and PBD-2 was shown to significantly inhibit the activation of the NF-κB pathway induced by LPS. The direct interaction of PBD-2 with TLR4 was revealed by isothermal titration calorimetry and far-Western blot in vitro and the coimmunoprecipitation of PBD-2 with TLR4 on RAW 264.7 cells. This interaction indicates one reason for the interference of NF-κB activation. Overall, this study showed that PBD-2 protected against bacterial infection through a direct bactericidal activity and alleviated inflammation by interfering with the TLR4/NF-κB pathway.

Long noncoding RNA UBE2R2-AS1 promotes glioma cell apoptosis via targeting the miR-877-3p/TLR4 axis

Introduction: Brain glioma is the most common type of primary malignancy in the central nervous system (CNS), with high recurrence and mortality rate, especially glioblastoma (GBM). Recent evidence suggests a role for many long noncoding RNAs (lncRNAs) in the pathogenesis, proliferation, apoptosis, metastasis, and chemotherapeutic resistance of cancer cells. Although the functions of some lncRNAs in the occurrence and development of gliomas have been confirmed, detailed mechanisms of action are lacking. Furthermore, the biological roles of many other lncRNAs in glioma have not been reported at all.

Methods: In this study, we identified a novel lncRNA, UBE2R2-AS1, which was dramatically downregulated in glioma compared with normal tissue, by performing microarray detection of six pairs of glioma samples and adjacent normal tissues. In vitro experiments demonstrated that UBE2R2-AS1 regulated glioma cell proliferation, apoptosis, and migration.

Results: UBE2R2-AS1 acted as a competing endogenous RNA (ceRNA) to target Toll-like receptor 4 (TLR4) mRNA by binding to miR-877-3p. Furthermore, lncRNA UBE2R2-AS1 suppressed glioblastoma cell growth, migration, and invasion, as well as promoting cell apoptosis by targeting miR-877-3p/TLR4 directly.

Conclusion: This information regarding UBE2R2-AS1 and its glioma-related molecular mechanisms will aid the future identification of new lncRNA-directed diagnostics and drug-targeting therapies.

A Combined Phytochemistry and Network Pharmacology Approach to Reveal the Potential Antitumor Effective Substances and Mechanism of Phellinus igniarius

Phellinus igniarius (P. igniarius) is a medicinal fungus that is widely used in East Asia for the adjuvant treatment of cancer. To elucidate the antitumor effective substances and mechanism of P. igniarius, we designed an approach incorporating cytotoxicity screening, phytochemical analysis, network pharmacology construction, and cellular and molecular experiments. The dichloromethane extract of P. igniarius (DCMPI) was identified as the active portion in HT-29 cells. Nineteen constituents were identified, and 5 were quantified by UPLC-ESI-Q/TOF-MS. Eight ingredients were obtained in the network pharmacology study. In total, 473 putative targets associated with DCMPI and 350 putative targets related to colon cancer were derived from online databases and target prediction tools. Protein-protein interaction networks of drug and disease putative targets were constructed, and 84 candidate targets were identified based on topological features. Pathway enrichment analysis showed that the candidate targets were mostly related to reactive oxygen species (ROS) metabolic processes and intrinsic apoptotic pathways. Then, a cellular experiment was used to validate the drug-target mechanisms predicted by the system pharmacology analysis. Experimental results showed that DCMPI increased intracellular ROS levels and induced HT-29 cell apoptosis. Molecular biology experiments indicated that DCMPI not only increased Bax and Bad protein expression and promoted PARP and caspase-3/9 cleavage but also down-regulated Bcl-2 and Bcl-xl protein levels to induce apoptosis in HT-29 cells. In conclusion, our study provides knowledge on the chemical composition and antitumor mechanism of P. igniarius, which may be exploited as a promising therapeutic option for colon cancer.

Regulated proteolysis of p62/SQSTM1 enables differential control of autophagy and nutrient sensing

The multidomain scaffold protein p62 (also called sequestosome-1) is involved in autophagy, antimicrobial immunity, and oncogenesis. Mutations in SQSTM1, which encodes p62, are linked to hereditary inflammatory conditions such as Paget's disease of the bone, frontotemporal dementia (FTD), amyotrophic lateral sclerosis, and distal myopathy with rimmed vacuoles. Here, we report that p62 was proteolytically trimmed by the protease caspase-8 into a stable protein, which we called p62^TRM We found that p62^TRM, but not full-length p62, was involved in nutrient sensing and homeostasis through the mechanistic target of rapamycin complex 1 (mTORC1). The kinase RIPK1 and caspase-8 controlled p62^TRM production and thus promoted mTORC1 signaling. An FTD-linked p62 D329G polymorphism and a rare D329H variant could not be proteolyzed by caspase-8, and these noncleavable variants failed to activate mTORC1, thereby revealing the detrimental effect of these mutations. These findings on the role of p62^TRM provide new insights into SQSTM1-linked diseases and mTORC1 signaling.

Cyanidin-3-O-β-glucoside, a Natural Polyphenol, Exerts Proapoptotic Effects on Activated Platelets and Enhances Megakaryocytic Proplatelet Formation

This study investigated whether the anthocyanin cyanidin-3-O-β-glucoside (Cy-3-g) could affect platelet apoptosis and proplatelet formation in vitro. Thrombin-stimulated or resting human platelets and Meg-01 megakaryocytes were incubated with Cy-3-g (0, 0.5, 5, or 50 μM). We found that the percentage of the platelet mitochondrial membrane potential treated with 5 and 50 μM Cy-3-g was significantly higher than control (15.50% ± 3.24% and 29.77% ± 4.06% versus 2.76% ± 1.33%, respectively; P < 0.05). Treatment with 5 and 50 μM Cy-3-g significantly increased phosphatidylserine exposure compared with control (40.56% ± 10.53% and 76.62% ± 8.28% versus 15.43% ± 3.93%, respectively; P < 0.05). Moreover, Cy-3-g significantly increased the expression of Bax, Bak, and cytochrome c while markedly decreasing Bcl-xL and Bcl-2 expression as well as stimulating caspase-3, caspase-9, caspase-8, Bid, and gelsolin cleavage in thrombin-activated platelets in a dose-dependent manner ( P < 0.05). However, no significant differences were observed in the apoptosis of resting platelets when treated with Cy-3-g ( P > 0.05). Furthermore, Cy-3-g significantly ( P < 0.05) enhanced cell viability (50 μM versus control, 1.34 ± 0.01 versus 0.35 ± 0.02), the number of colony-forming unit-megakaryocytes (50 μM versus control, 38 ± 3 versus 8 ± 3), CD41 expression (50 μM versus control, 96.80% ± 2.55% versus 25.57% ± 2.86%), DNA ploidy (16N) (50 μM versus control, 19.73% ± 2.34% versus 4.42% ± 1.96%), and proplatelet formation (50 μM versus control, 27.5% ± 3.77% versus 7.67% ± 2.25%) in Meg-01 cells. In conclusion, Cy-3-g promotes activated platelet apoptosis and enhances megakaryocyte proliferation, differentiation, and proplatelet formation in vitro.

Anti-tumor properties of anthocyanins from Lonicera caerulea 'Beilei' fruit on human hepatocellular carcinoma: In vitro and in vivo study

In this study, the anthocyanin from Lonicera caerulea 'Beilei' fruit (ABL) was extracted and purified. The purified component (ABL-2) was then evaluated for its anti-tumor properties on human hepatoma cells (SMMC-7721) in vitro and the murine hepatoma cells (H22) in vivo. In vitro, ABL-2 not only significantly inhibited the growth of SMMC-7721 cells, but also remarkably blocked the cells' cycle in G2/M phase, inducing DNA damage and eventually leading to apoptosis. In vivo, ABL also killed tumor cells, inhibited tumor growth, and improved the survival status of H22 tumor-bearing mice. These effects were associated with an increase in the activities of antioxidase and a decrease in the level of lipid peroxidation, as evidenced by changes in SOD, GSH-Px, GSH, and MDA levels. In addition, ABL-2 also regulated the levels of immune cytokines including IL-2, IFN-γ, and TNF-α. These results revealed that ABL-2 exerts an effective anti-tumor effect by dynamically adjusting the REDOX balance and improving the immunoregulatory activity of H22 tumor-bearing mice. High performance liquid chromatography (HPLC) analysis revealed that cyanidin-3,5-diglucoside (8.16 mg/g), cyanidin-3-glucoside (387.60 mg/g), cyanidin-3-rutinoside (23.62 mg/g), and peonidin-3-glucoside (22.20 mg/g) were the main components in ABL-2, which may contribute to its anti-tumor activity.

Low doses of LPS exacerbate the inflammatory response and trigger death on TLR3-primed human monocytes

TLR sensing of pathogens triggers monocyte activation to initiate the host innate immune response to infection. Monocytes can dynamically adapt to different TLR agonists inducing different patterns of inflammatory response, and the sequence of exposure to TLRs can dramatically modulate cell activation. Understanding the interactions between TLR signalling that lead to synergy, priming and tolerance to TLR agonists may help explain how prior infections and inflammatory conditioning can regulate the innate immune response to subsequent infections. Our goal was to investigate the role of MyD88-independent/dependent TLR priming on modulating the monocyte response to LPS exposure. We stimulated human blood monocytes with agonists for TLR4 (LPS), TLR3 (poly(I:C)) and TLR7/8 (R848) and subsequently challenged them to low doses of endotoxin. The different TLR agonists promoted distinct inflammatory signatures in monocytes. Upon subsequent LPS challenge, LPS- and R848-primed monocytes did not enhance the previous response, whereas poly(I:C)-primed monocytes exhibited a significant inflammatory response concomitant with a sharp reduction on cell viability. Our results show that TLR3-primed monocytes are prompted to cell death by apoptosis in the presence of low endotoxin levels, concurrent with the production of high levels of TNFα and IL6. Of note, blocking of TNFR I/II in those monocytes did reduce TNFα production but did not abrogate cell death. Instead, direct signalling through TLR4 was responsible of such effect. Collectively, our study provides new insights on the effects of cross-priming and synergism between TLR3 and TLR4, identifying the selective induction of apoptosis as a strategy for TLR-mediated host innate response.

Protective effect of Coptisine from Rhizoma Coptidis on LPS/D-GalN-induced acute liver failure in mice through up-regulating expression of miR-122

Coptisine (COP), one of the main active ingredients of Rhizoma Coptidis, reportedly has anti-inflammatory, anti-colon cancer properties, but it remains elusive whether COP owns hepatoprotective activity. Mice were pretreated with COP for 7d prior to lipopolysaccharide/d-galactosamine (LPS/D-GalN) administration to detect the hepatic protective effects of COP. The mechanism was explored in using HepG2 cells with low level of miR-122 and LO2 cells with high level of miR-122, combining with miR-122 agomir transfection by means of detecting the expression of miR-122 and proteins, clinical index and apoptosis. COP ameliorated the LPS/D-GalN-induced liver failure by lowering serum levels of ALT and AST, raising hepatic GSH and SOD levels, and maintaining the morphology of hepatocytes, along with an increase in miR-122 expression in mice. The results in vitro indicated that, after miR-122 mimic administration, the alone treatment of COP and the co-treatment of COP and LPS transfection obviously promoted the apoptosis of HepG2, which was increased by 152.67% and 113.97% compared with NC (P < 0.05 vs NC). LPS significantly induced the apoptosis of L02 cells, but COP treatment attenuated that of L02 cells. Further analysis showed that COP increased the miR-122 level and the expression of Bax, cleaved-casp3 and decreased Bcl-2, Bcl-xL in LPS-treated HepG2 cells. COP increased the miR-122 level but decreased the expression of TLR4, Bcl-2, Bcl-xL in LPS-treated L02 cells. COP attenuated LPS/D-GalN-induced ALF by up-regulating the level of miR-122, synergistically promoting apoptosis, and suggesting COP which showed a potential protective effect on ALF.

The regulatory effect of oxymatrine on the TLR4/MyD88/NF-κB signaling pathway in lipopolysaccharide-induced MS1 cells

BACKGROUND

Oxymatrine (OM), a major quinolizidine alkaloid extracted from the roots of Sophora flavescens, has been proved to regulate a variety of signaling pathways to produce a wide range of pharmacological effects.

OBJECTIVES

The regulatory effects of OM on the TLR4/MyD88/NF-κB signaling pathway under the stimulation of lipopolysaccharide (LPS) in MS1 cells were explored to illuminate the potential anti-inflammatory mechanism of OM for pancreatitis treatment.

METHODS

The signaling molecules related to the TLR4/MyD88/NF-κB pathway in MS1 cells were detected by Western blotting under different conditions, including OM pretreatment and LPS stimulation. The mRNA expression levels of TLR4, MyD88, NF-κB p65 and IκBα were detected by real-time PCR. The NF-κB p65 nuclear translocation in MS1 cells was measured by immunofluorescence, and the pro-inflammatory cytokine of IL-1β was detected by ELISA.

RESULTS

Increased levels of TLR4, MyD88 and NF-κB p65, induced by LPS stimulation, were significantly inhibited by OM pretreatment in MS1 cells. The decreased protein, but not mRNA, level of IκBα induced by LPS stimulation was increased by OM pretreatment. Meanwhile, LPS induced NF-κB p65 protein translocation to the nucleus as well as LPS increased expression of IL-1β were also inhibited by OM pretreatment.

CONCLUSION

Inhibitory effects of OM on molecules related to the TLR4/MyD88/NF-κB signaling pathway in pancreatic microvascular endothelial cells can alleviate inflammatory responses.

Tryptophan end-tagging for promoted lipopolysaccharide interactions and anti-inflammatory effects

The objective of the present study is the investigation of possibilities for boosting peptide anti-inflammatory effects by tryptophan end-tagging, including identification of underlying mechanisms for this. In doing so, effects of tryptophan end-tagging of KYE21 (KYEITTIHNLFRKLTHRLFRR), a peptide derived from heparin co-factor II, on membrane and lipopolysaccharide (LPS) interactions were investigated by ellipsometry, NMR, fluorescence spectroscopy, and circular dichroism measurements. Through its N-terminal W stretch, WWWKYE21 displays higher membrane binding, liposome rupture, and bacterial killing than unmodified KYE21. Analogously, W-tagging promotes binding to E. coli LPS and to its endotoxic lipid A moiety. Furthermore, WWWKYE21 causes more stable peptide/LPS complexes than KYE21, as evidenced by detailed NMR studies, adopting a pronounced helical conformation, with a large hydrophobic surface at the N-terminus due to the presence of W-residues, and a flexible C-terminus due to presence of several positively charged arginine residues. Mirroring its increased affinity for LPS and lipid A, WWWKYE21 displays strongly increased anti-inflammatory effect due to a combination of direct lipid A binding, peptide-induced charge reversal of cell membranes for LPS scavenging, and peptide-induced fragmentation of LPS aggregates for improved phagocytosis. Importantly, potent anti-inflammatory effects were observed at low cell toxicity, demonstrated for both monocytes and erythrocytes.