Antioxidant effects of quercetin on Chinese hamster ovary (CHO) cells and their electroporation

The normal microbial occupants of the mammalian intestine are crucial for maintaining gut homeostasis, yet the mechanisms by which intestinal cells perceive and respond to the microbiota are largely unknown. Intestinal epithelial contact with commensal bacteria and/or their products has been shown to activate noninflammatory signaling pathways, such as extracellular signal-related kinase (ERK), thus influencing homeostatic processes. We previously demonstrated that commensal bacteria stimulate ERK pathway activity via interaction with formyl peptide receptors (FPRs). In the current study, we expand on these findings and show that commensal bacteria initiate ERK signaling through rapid FPR-dependent reactive oxygen species (ROS) generation and subsequent modulation of MAP kinase phosphatase redox status. ROS generation induced by the commensal bacteria Lactobacillus rhamnosus GG and the FPR peptide ligand, N-formyl-Met-Leu-Phe, was abolished in the presence of selective inhibitors for G protein-coupled signaling and FPR ligand interaction. In addition, pretreatment of cells with inhibitors of ROS generation attenuated commensal bacteria-induced ERK signaling, indicating that ROS generation is required for ERK pathway activation. Bacterial colonization also led to oxidative inactivation of the redox-sensitive and ERK-specific phosphatase, DUSP3/VHR, and consequent stimulation of ERK pathway signaling. Together, these data demonstrate that commensal bacteria and their products activate ROS signaling in an FPR-dependent manner and define a mechanism by which cellular ROS influences the ERK pathway through a redox-sensitive regulatory circuit.

Hypoxia is known to stimulate reactive oxygen species (ROS) generation. Because reduced glutathione (GSH) is compartmentalized in cytosol and mitochondria, we examined the specific role of mitochondrial GSH (mGSH) in the survival of hepatocytes during hypoxia (5% O2). 5% O2 stimulated ROS in HepG2 cells and cultured rat hepatocytes. Mitochondrial complex I and II inhibitors prevented this effect, whereas inhibition of nitric oxide synthesis with Nomega-nitro-L-arginine methyl ester hydrochloride or the peroxynitrite scavenger uric acid did not. Depletion of GSH stores in both cytosol and mitochondria enhanced the susceptibility of HepG2 cells or primary rat hepatocytes to 5% O2 exposure. However, this sensitization was abrogated by preventing mitochondrial ROS generation by complex I and II inhibition. Moreover, selective mGSH depletion by (R,S)-3-hydroxy-4-pentenoate that spared cytosol GSH levels sensitized rat hepatocytes to hypoxia because of enhanced ROS generation. GSH restoration by GSH ethyl ester or by blocking mitochondrial electron flow at complex I and II rescued (R,S)-3-hydroxy-4-pentenoate-treated hepatocytes to hypoxia-induced cell death. Thus, mGSH controls the survival of hepatocytes during hypoxia through the regulation of mitochondrial generation of oxidative stress.

IEX-1 (immediate early response gene X-1) is a stress-inducible gene. Its overexpression can suppress or enhance apoptosis dependent on the nature of stress, yet the polypeptide does not possess any of the functional domains that are homologous to those present in well characterized effectors or inhibitors of apoptosis. This study using sequence-targeting mutagenesis reveals a transmembrane-like integrated region of the protein to be critical for both pro-apoptotic and anti-apoptotic functions. Substitution of the key hydrophobic residues with hydrophilic ones within this region impairs the capacity IEX-1 to positively and negatively regulate apoptosis. Mutations at N-linked glycosylation and phosphorylation sites or truncation of the C terminus of IEX-1 also abrogated its potential to promote cell survival. However, distinguished from the transmembrane-like domain, these mutants preserved pro-apoptotic activity of IEX-1 fully. On the contrary, mutation of nuclear localization sequence, despite its importance in apoptosis, did not impede IEX-1-mediated cell survival. Strikingly, all the mutants that lose their anti-apoptotic ability are unable to prevent acute increases in production of intracellular reactive oxygen species (ROS) at the initial onset of apoptosis, whereas those mutants that can sustain anti-death function also control acute ROS production as sufficiently as wild-type IEX-1. These findings suggest a critical role of IEX-1 in regulation of intracellular ROS homeostasis, providing new insight into the mechanism underlying IEX-1-mediated cell survival.

A HIF-1 Target, ATIA, Protects Cells from Apoptosis by Modulating the Mitochondrial Thioredoxin, TRX2

Biometals play an important role in Alzheimer disease, and recent reports have described the development of potential therapeutic agents based on modulation of metal bioavailability. The metal ligand clioquinol (CQ) has shown promising results in animal models and small phase clinical trials; however, the actual mode of action in vivo has not been determined. We now report a novel effect of CQ on amyloid beta-peptide (Abeta) metabolism in cell culture. Treatment of Chinese hamster ovary cells overexpressing amyloid precursor protein with CQ and Cu(2+) or Zn(2+) resulted in an approximately 85-90% reduction of secreted Abeta-(1-40) and Abeta-(1-42) compared with untreated controls. Analogous effects were seen in amyloid precursor protein-overexpressing neuroblastoma cells. The secreted Abeta was rapidly degraded through up-regulation of matrix metalloprotease (MMP)-2 and MMP-3 after addition of CQ and Cu(2+). MMP activity was increased through activation of phosphoinositol 3-kinase and JNK. CQ and Cu(2+) also promoted phosphorylation of glycogen synthase kinase-3, and this potentiated activation of JNK and loss of Abeta-(1-40). Our findings identify an alternative mechanism of action for CQ in the reduction of Abeta deposition in the brains of CQ-treated animals and potentially in Alzheimer disease patients.

Open AccessCCS ChemistryRESEARCH ARTICLE1 Feb 2022Sonosensitized Aggregation-Induced Emission Dots with Capacities of Immunogenic Cell Death Induction and Multivalent Blocking of Programmed Cell Death-Ligand 1 for Amplified Antitumor Immunotherapy Shaorui Jia†, Zhiyuan Gao†, Zelin Wu, Heqi Gao, He Wang, Hanlin Ou and Dan Ding Shaorui Jia† Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071 , Zhiyuan Gao† Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071 , Zelin Wu Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071 , Heqi Gao Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071 , He Wang Department of Urology, First Affiliated Hospital of Soochow University, Suzhou 215006 , Hanlin Ou Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071 and Dan Ding *Corresponding author: E-mail Address: [email protected] Key Laboratory of Bioactive Materials Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071 https://doi.org/10.31635/ccschem.021.202101458 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail The combination of immunogenic cell death (ICD) induction and immune checkpoint blockade has emerged as a major direction of cancer immunotherapy. Among currently available ICD inducers, sonosensitizers that produce reactive oxygen species (ROS) under an external trigger to evoke ICD of tumor cells have shown great promise. However, a highly efficient sonosensitizer-based ICD inducer with an aggregation-induced emission (AIE) characteristic has yet to be developed. Herein, a novel AIE sonosensitizer with a twisted molecular structure, very small energy gap between the singlet and triplet excited states (ΔEST), and efficient ROS generation ability, which can serve as an effective ICD inducer, is reported for sonodynamic processes in cancer immunotherapy. Furthermore, an AIE sonosensitizer-based nanosystem with surface modification of anti-PD-L1 peptide is constructed for boosting antitumor immunotherapy. In this system, AIE sonosensitizer-mediated sonodynamic therapy can successfully convert a hypoimmunogenic cold tumor to a hot one and further facilitate the multivalent blocking of programed death ligand (PD-L1) by anti-PD-L1 peptides. Such an advanced nanosystem could effectively initiate the activation of antitumoral immune reactions and modulation of an immunosuppressive microenvironment, contributing to systemic antitumor effects to further inhibit the growth of distant tumors. Download figure Download PowerPoint Introduction Antitumor immunotherapy, which boosts specific cytotoxic T cells to eliminate tumor cells, is recognized as an effective cancer treatment strategy.1 Currently, inducing immunogenic cell death (ICD) of tumor cells is an effective strategy for enhancing recruitment and infiltration of specific cytotoxic T cells into solid tumors (e.g., triple negative breast cancer), converting a cold tumor, with a paucity of T cell infiltration, to hot.2–4 During ICD of tumors, tumor-associated antigens (TAAs) and damage-associated molecular patterns (DAMPs) are generated, featuring surface-exposed calreticulin (ecto-CRT), adenosine triphosphate (ATP) secretion, and release of high-mobility group protein B1 (HMGB1) and heat shock protein 70 (HSP70).5,6 DAMPs act as a vital signal and a natural adjuvant to stimulate the presentation of TAA by antigen-presenting cells (APCs) (such as dendritic cells (DCs)) to T cells, which lead to the further activation of tumor-specific T cell-mediated immune response.7,8 Because of the pivotal role of ICD in antitumor immunotherapy, the development of highly effective ICD inducers with few side effects has attracted great interest during the past decade.5,9 Among currently available ICD inducers, photosensitizers evoke ICD of tumor cells by producing reactive oxygen species (ROS) upon light irradiation, which has showed conspicuous spatiotemporal precision and excellent biocompatibility.10 Our previous work has demonstrated that an aggregation-induced emission (AIE) photosensitizer with high ROS production capacity can massively induce sufficient ICD to evoke antitumor immunity.11,12 However, the limited penetration depth of light is a major challenge for the application of photosensitizer-based photodynamic therapy (PDT) in vivo.13 Sonodynamic therapy (SDT), derived from PDT, which utilizes ultrasound (US) to activate the sonosensitizer to produce ROS, enables deep tissue penetration, provides a more effective and safer strategy for the treatment of deep tumors, and shows unique advantages and great potential in antitumor immunotherapy.14–16 The mechanism of SDT is a complex, combinational output of different mechanisms.17–19 Among them, sonoluminescence was proven important to generate ROS.15,20 Sonoluminescence refers to the light emitted by the collapse of a bubble that is generated by US irradiation, which can activate the energy-matching photoactive sonosensitizers and generate the same photochemical reaction like PDT.21,22 For traditional organic photosensitizers with planar molecular structure, strong intermolecular interactions (e.g., π–π stacking) facilitate a nonradiative pathway of excited states, and the aggregation of photosensitizers within nanoparticles (NPs) causes quenching of the emission and ROS generation.23,24 At present, many organic photosensitizers that can be used as sonosensitizers to produce ROS, kill tumor cells, and induce ICD in tumor cells have been reported in SDT.25–27 Similar to photosensitizers, the aggregation-caused quenching (ACQ) effect also occurs when they are used as sonosensitizers in the aggregate state.28,29 Fortunately, sonosensitizers with AIE properties provide a good solution for the ACQ problem.30,31 AIE sonosensitizers have peripheral intramolecular motion units (e.g., rotating benzene rings) and a three-dimensional (3D) molecular structure.32,33 The 3D molecular structure significantly reduces the intermolecular interactions in NPs and aggregates. Meanwhile, the steric hindrance restricts the molecular motion in the excited state, which allows as much absorbed excitation energy as possible to be used in fluorescence emission or ROS generation.34,35 To the best of our knowledge, however, the ICD effect of AIE in SDT has never been studied. The reason may be the lack of appropriate strategies and AIE sonosensitizers with high efficiency. The application of SDT in immune system activation also faces challenges. Therefore, the design of an efficient AIE sonosensitizer is urgently needed to explore whether AIE can build an effective platform for sonosensitivity-based ICD inducers. Additionally, after successfully eliciting antitumor immune response by the induction of ICD, tumors may express autoprotective checkpoint molecules such as programmed cell death-ligand 1 (PD-L1) to bind with programmed death-1 (PD-1) on activated T cells, escaping attack from the immune system.36–38 Thus, an immune checkpoint blockade (ICB), such as the PD-1/PD-L1 blockade, has been employed to block PD-1/PD-L1 interaction to improve the tumor cell killing effect of T cells, thereby enhancing the inhibition efficacy against ICD-induced hot tumors.39–43 Although ICB holds great promise in cancer treatment, its therapeutic effect is largely limited by the insensitive response and insufficient T cells in cold tumors.44,45 Moreover, the synergistic anticancer efficacy of the integrated ICD induction and ICB is superior to monotherapy with only one of them.37,46,47DPPA (CNYSKPTDRQYHF, D-type PD-L1 peptide antagonists) can effectively block the PD-1/PD-L1 pathway, offering salient advantages such as higher stability, lower cost, and easier modification as compared with clinical anti-PD-L1 monoclonal antibodies.48,49 Consequently, for tremendously amplifying the effect of antitumor immunotherapy, the strategy of combing anti-PD-L1 peptide and ICD inducer in a single nanosystem is valuable and highly desirable but currently rare.50,51 Herein, we report sonosensitized AIE ICD inducer-based dots modified with anti-PD-L1 peptides on the surface for considerable improvement of antitumor immunotherapy outcomes. We designed and synthesized three new AIE luminogens (AIEgens): diphenylamino (DPA)-tetraphenylethylene (TPE)-(4-styryl-cyano)pyridinium salt (SCP), triphenylamine (TPA)-Ph-SCP, and TPA-2Ph-SCP). They have D–π–A structure and abundant intramolecular movement unit. Compared with TPA-Ph-SCP and TPA-2Ph-SCP, DPA-TPE-SCP has a more twisted molecular structure and very small ΔEST, which lead to stronger AIE activity, weaker intermolecular interactions of aggregates, and more efficient ROS generation. By comparison, DPA-TPE-SCP is not only the best photosensitizer, but also the best sonosensitizer. AIE sonosensitizers under US excitation showed superior ICD induction capability when compared with the reported sonosensitizing ICD inducer hematoporphyrin monomethyl ether (HMME), and successfully transformed a cold tumor into a hot one that was sensitized to PD-L1 blocking in vivo. Subsequently, surface modification of sonosensitized AIE dots with anti-PD-L1 peptides endowed them complementary advantages. In vivo experiments demonstrate that such function-cooperative dots significantly enhanced immune responses and relieved immune suppression, triggering a systemic antitumor immune therapeutic effect by virtue of the excellent ICD induction and multivalent PD-L1 blockade. Thus, this work not only provides a molecular guideline to design advanced sonosensitizer-based ICD inducers but also introduces new insights into the combination of ICD induction and ICB for synergistic antitumor immunotherapy (Scheme 1). Scheme 1 | Synthesis of AIE-dots-DPPA and the mechanism of antitumor immune responses induced by AIE-dots-DPPA-mediated sonodynamic therapy. Download figure Download PowerPoint Experimental Methods Computational method Structures of TPA-Ph-SCP, TPA-2Ph-SCP, and DPA-TPE-SCP were optimized in the water phase with the B3LYP method and 6-311G (d, p) basis set, Gaussian 09 program. Energy levels of S1–S6 and T1–T6 were calculated by the vertical excitation of the above optimized structures, with the same method of B3LYP/6-311G (d, p). Preparation of nano-sonosensitizer Nano-sonosensitizer was formulated by a nanoprecipitation approach using an amphiphilic co-polymer, DSPE-PEG2000. In brief, sonosensitizer (1 mg) and DSPE-PEG2000 (3 mg) were dissolved in 1 mL of tetrahydrofuran (THF); the solution was added dropwise into 9 mL of water undergoing sonication (3 min) by a microtip probe sonicator (XL2000, Misonix). An air pump was subsequently used to volatilize THF in the mixture to obtain a sonosensitizer-encapsulated dot aqueous solution. Then, the sonosensitizer-encapsulated dot solution was purified by 5000 rpm ultrafiltration for 10 min and filtration using a 0.45 μm syringe driven filter. Preparation of DPPA-conjugated dots DPPA peptides were modified on the AIE dots. First, DPPA peptides were added to the dots suspension, and then the suspension was stirred for 12 h to couple the thiol group of the peptide with the maleimide group of PEG2000 via the click reaction. Peptides that were not conjugated to the dots were then removed by centrifugation. ROS detection in 4T1 cells The 4T1 cancer cells were incubated in special confocal chambers with each nano-sonosensitizer (10 μg/mL of DPA-TPE-SCP dots, 10 μg/mL of HMME NPs) for 4 h at 37 °C. Subsequently, the cells were washed with 1× phosphate-buffered saline (PBS) three times, and then incubated with 2′,7′-dichlorodihydrofluorescein diacetate (DCF-DA; 20 μM) in FBS free culture medium. The above-mentioned process was performed in the dark. Then, under US exposure (1 MHz, 50% duty cycle, 0.5 W/cm2, 3 min), the cells were imaged with confocal laser scanning microscopy (CLSM) for DCF detection (Ex: 488 nm, Em: 530 ± 20 nm). Ecto-CRT staining in 4T1 cancer cells After the 4T1 cancer cells were incubated with each ICD inducer (10 μg/mL of DPA-TPE-SCP dots, 10 μg/mL of HMME NPs) for 4 h at 37 °C, the cells were washed and irradiated by US for 3 min (1 MHz, 50% duty cycle, 0.5 W/cm2). After 12 h, the cells were washed by precooling 1× saline, fixed with 4% paraformaldehyde on ice for 20 min, and then successively incubated with anticalreticulin antibody (ab2907, 1:200 dilution with 1× PBS) for 2 h and stained with Alexa Fluor 633-conjugated secondary antibody (1:200 dilution with 1× PBS) for another 2 h. The ecto-CRT expression of each ICD inducer-treated cancer cell was visualized by the ecto-CRT immunofluorescence using CLSM with the excitation at 633 nm and signal acquisition in the range from 640 to 670 nm. Detection of extracellular ATP, HMGB1, and HSP70 The 4T1 cancer cells (1 × 105 cells mL−1) were cultured in a black 12-well plate. After adherence, the 4T1 cancers cells were incubated with 10 μg/mL of DPA-TPE-SCP dots and 10 μg/mL of HMME NPs for 4 h at 37 °C, respectively. Next, the treated cells were washed and irradiated by US for 3 min (1 MHz, 50% duty cycle, 0.5 W/cm2). After 12 h, the supernatants were collected and then subjected to centrifugation using 12,000 rpm for 10 min at 4 °C, which was followed by addition of protease and phosphatase inhibitors into the supernatants. Furthermore, the cancer cells in each group were harvested and lysed, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as the internal control. Finally, the extracellular levels of HMGB1 and HSP70 were analyzed by western blot with the anti-HMGB1 antibody (1:500, Abcam, ab79823) and anti-HSP70 antibody (1∶1000, Abcam, ab181606), respectively. The level of secreted ATP was quantitatively determined by ATP Bioluminescent Assay Kit per manufacturer's instruction. In vivo SDT treatment 4T1 cells (1 × 106) dispersed in 50 μL of 1× PBS were injected into the second breast fat pad on the right side of each BALB/c mouse. The mice bearing 4T1 tumors were randomly divided into four groups when their tumors reached about 50 mm3. The AIE dots were intravenously injected into the mice three times on day 2, 4 and 6, respectively (once a day for three days (2, 4, and 6)). The tumors were exposed to US irradiation (1.0 MHz, 50% duty cycle, 1.5 W/cm2, 5 min) at 6-h post each injection. The tumor volume was measured by a caliper and determined with the following formula: Volume = Width2 × Length/2. The mice with tumors reaching 1500 mm3 were euthanized due to the standard animal protocol in this work. To establish a bilateral 4T1 orthotopic tumor model, 4T1 cells (1 × 106) were injected into the second breast fat pad on the right side of each female BALB/c mouse as primary tumor. Four days later, 4T1 cells (2 × 105) were injected into the second breast fat pad on the left side of mice as a distant tumor. The mice bearing ∼50 mm3 of primary tumors were randomly divided into four groups. The AIE dots were intravenously injected into the mice three times on day 2, 4 and 6, respectively (once a day for three days (2, 4, and 6)). At 6 h after each injection, the tumors were exposed to US irradiation for 5 min (1.0 MHz, 50% duty cycle, 1.5 W/cm2). The tumor volume was measured by a caliper and determined with the following formula: Volume = Width2 × Length/2. Flow cytometry analysis At designated time points, lymph nodes and tumors were harvested and homogenized to single-cell suspensions. After that, cell suspensions of lymph nodes were co-stained with anti-CD11c-FITC, anti-CD86-APC, and anti-CD80-PE for flow cytometry analysis of DCs. Single-cell suspensions in tumors were co-stained with different antibodies for flow cytometry analysis of CD8+ T cells (anti-CD3-FITC, anti-CD8-PE, or anti-CD8-APC), PD-L1+ tumor cells (anti-CD45-PE and anti-PD-L1-APC), Treg cells (anti-CD3-FITC, anti-CD4-APC, anti-CD25-PerCP/Cyanine5.5, and anti-Foxp3-PE), and IFN-γ+ of CD8+ T cells (anti-CD3-FITC, anti-CD8-APC, and anti-IFN-γ-PE). Statistical analysis Quantitative data are shown as mean ± standard deviation (SD). All the experiments were repeated at least three times. Statistical comparisons were made by ANOVA analysis and two-sample Student's t-test. P value < 0.05 was considered statistically significant. Results and Discussion Design, synthesis, and characterization of AIEgens Based on our design strategy, the phenylethylene core was used as a π-linker, and compared to triphenylethylene and diphenylethylene, TPE is an excellent AIE skeleton. The D–π–A structure was constructed using a DPA block as an electronic donor (D) and the pyridinium as an electronic acceptor (A). The compounds DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP were designed and synthesized according to the synthetic route shown in Figure 1a. Compound 1 was prepared through a Horner–Wadsworth–Emmons reaction. After quenching with dimethylformamide (DMF), compound 1 containing bromine was functionalized to afford the corresponding aldehyde derivatives, and DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP were obtained from the Knoevenagel condensation of compound 2 and SCP under basic conditions (for detailed synthetic routes of all compounds see Supporting Information Scheme S1). The intermediates were characterized by 1H NMR, and DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP were characterized by 1H NMR, 13C NMR, and high-resolution mass spectrometry (HRMS) ( Supporting Information Figures S1–S17). Figure 1 | (a) Synthetic route to DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP. (b) Plot of ln(A0/A) against light exposure time, where A0 and A are the ABDA absorbance (378 nm) before and after irradiation, respectively. (c) Jablonski diagrams displaying the photophysical properties of the DPA-TPE-SCP. (d) HOMO–LUMO distributions by DFT calculations of DPA-TPE-SCP. (e) Energy levels of S1–S6 and T1–T6 calculated by the vertical excitation of the optimized structures in (f). (f) The dihedral angles of DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP by DFT calculations. Download figure Download PowerPoint Photophysical properties The absorption and photoluminescence (PL) spectra of DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP are shown in Supporting Information Figure S18. The conjugated structure of TPA-Ph-SCP, TPA-2Ph-SCP, and DPA-TPE-SCP becomes more and more distorted, so that their absorption peaks show hypochromatic shifts at 447, 382, and 350 nm; gradual red-shifting maximum emission wavelengths are located at 628, 630, and 638 nm. The PL quantum yields (QYs) of DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP in the solid state were 12.4%, 7.9%, and 2.6%, respectively. When a poor solvent (toluene) was gradually added to the good solution [dimethyl sulfoxide (DMSO)], aggregate formation occurred, and the PL intensities of DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP were significantly intensified, which prove that DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP have an obvious AIE feature. Notably the DPA-TPE-SCP showed the best AIE property when comparing the PL intensity of DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP in a DMSO/toluene mixture with 99% toluene fraction to that in pure DMSO ( Supporting Information Figure S18). Because high ROS generation capacity is a prerequisite for an ICD inducer, we next studied and compared the ROS production of DPA-TPE-SCP, TPA-Ph-SCP, and in a 10 μM) under light irradiation (10 with as the ROS shown in Figure the ABDA of DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP were and that DPA-TPE-SCP is an mechanism Based on the Jablonski the fixed absorption energy excited by light is through three fluorescence through followed by production of ROS or and nonradiative one or energy as much absorbed energy as possible on the is an effective to the efficacy of an To the mechanism of the superior ROS production of DPA-TPE-SCP compared to and TPA-Ph-SCP, calculations were The on electronic structures in the state that DPA-TPE-SCP, TPA-2Ph-SCP, and TPA-Ph-SCP a with the molecular on the and the molecular located on the and Supporting Information Figure in Figure TPA-Ph-SCP has a gap between the singlet and triplet excited of However, using the TPE as the π-linker, DPA-TPE-SCP has a very small value of to the highly ΔEST, was which for the superior ROS generation capability of DPA-TPE-SCP. shown in Figure the optimized structures calculated by DFT that compared with and TPA-Ph-SCP, DPA-TPE-SCP has a much molecular a TPE group used as a π-linker, the structure becomes more For the same dihedral between and to and in DPA-TPE-SCP from the of groups ( Supporting Information Figure The more twisted molecular structure the intermolecular interactions such as π–π and nonradiative in the or solid state, the absorbed excitation energy flow to the Therefore, successfully DPA-TPE-SCP showed higher fluorescence and ROS generation and TPA-Ph-SCP is for DPA-TPE-SCP, TPA-2Ph-SCP, and Such excellent of DPA-TPE-SCP is to our molecular design structure, of intramolecular motion units on π-linker, 3D twisted molecular which the process and the ROS generation efficiency. Preparation of AIE dots and detection of ROS in dots The AIE dots were prepared by the method The amphiphilic was used to the microscopy that DPA-TPE-SCP dots with of about nm, respectively dot has on the ROS generation of DPA-TPE-SCP, as by the same ABDA of DPA-TPE-SCP (10 μM) solution and DPA-TPE-SCP dots (10 on upon light ( Supporting Information Figure shown in Figure the reported dots and dots with excellent ROS production and the available sonosensitized compound HMME NPs were used to the ROS production of DPA-TPE-SCP dots dots and TPA-Ph-SCP dots under US irradiation (1 MHz, 50% duty cycle, 1.5 W/cm2). DPA-TPE-SCP dots showed higher ROS generation the sonosensitizers The of ROS production the ROS that the mechanism of DPA-TPE-SCP dots producing ROS may be activated by Next, was used to the species of The was with water and DPA-TPE-SCP dots, followed by US DPA-TPE-SCP dots showed an obvious For was used as the under detection and the that the dots could also generate post US irradiation Consequently, DPA-TPE-SCP dots were then as AIE dots for the following sonosensitized ICD induction Figure 2 | (a) The of sonosensitized AIE dots. (b) and of DPA-TPE-SCP dots. (c) The structure of and (d) Plot of ln(A0/A) against ultrasound (US) exposure time, where A0 and A are the ABDA absorbance (378 nm) before and after irradiation, respectively. (e) generation by DPA-TPE-SCP dots and water with US using (f) generation by DPA-TPE-SCP dots and water with US using Download figure Download PowerPoint In SDT effect and ICD induction by AIE dots has been that SDT can evoke ICD of cancer cells by producing First, of DPA-TPE-SCP dots by 4T1 breast cancer cells within 4 h was analyzed by flow cytometry ( Supporting Information Figure Next, the ROS generation level in 4T1 cells was by of by ROS to the upon US irradiation for 3 min (1 MHz, 0.5 the CLSM of the 4T1 cells treated with DPA-TPE-SCP dots showed the fluorescence and Supporting Information Figure the fluorescence intensity of dots is higher that of NPs ( Supporting Information Figure the excellent ROS production capacity of DPA-TPE-SCP dots. Then, was used to the therapeutic effect of SDT on 4T1 cells in and The of DPA-TPE-SCP dots in 4T1 cells was at different US the great of DPA-TPE-SCP dots. After exposure to US for 3 min (1 MHz, 0.5 the of 4T1 cells as the of DPA-TPE-SCP dots Furthermore, under different US irradiation time, the AIE 4T1 cancer cells more cell that of HMME All demonstrate that DPA-TPE-SCP dots can produce highly efficient ROS in 4T1 cells, a superior SDT effect by DPA-TPE-SCP dots in Figure 3 | (a) CLSM the ROS levels in 4T1 cancer cells after was used as the ROS 50 (b) Cell of 4T1 cells incubated with different of DPA-TPE-SCP dots with or US (c) Cell of 4T1 cells after with DPA-TPE-SCP dots and HMME followed by US irradiation with different (d) CLSM of ecto-CRT on 4T1 cells surface The cell were stained by 50 (e) Quantitative of ATP in the supernatants of 4T1 cells after different (f) the protein levels of HMGB1 and HSP70 in the 4T1 cell

UVB Radiation Induces Apoptosis in Keratinocytes by Activating a Pathway Linked to “BLT2-Reactive Oxygen Species”

From human and animal studies, estrogen is known to protect the myocardium from an ischemic insult. However, there is limited knowledge regarding mechanisms by which estrogen directly protects cardiomyocytes. In this report, we employed an in vitro model, in which cultured rat cardiomyocytes underwent prolonged hypoxia followed by reoxygenation (H/R), to study the cardioprotective mechanism of estrogen. 17-beta-estradiol (E2) acting via estrogen receptors inhibited H/R-induced apoptosis of cardiomyocytes. Mitochondrial reactive oxygen species (ROS) generated from H/R activated p38alpha MAPK, and inhibition of p38alpha with SB203580 significantly prevented H/R-induced cell death. E2 suppressed ROS formation and p38alpha activation by H/R and concomitantly augmented the activity of p38beta. Unlike p38alpha, p38beta was little affected by H/R. Dominant negative p38beta protein expression decreased E2-mediated cardiomyocyte survival and ROS suppression during H/R stress. The prosurvival signaling molecule, phosphoinositol-3 kinase (PI3K), has previously been linked to cell survival following ischemia-reperfusion injury. Here, E2-activated PI3K was found to inhibit ROS generated from H/R injury, leading to inhibition of downstream p38alpha. We further linked these signaling pathways in that p38beta was activated by E2 stimulation of PI3K. Thus, E2 differentially modulated two major isoforms of p38, leading to cardiomyocyte survival. This was achieved by signaling through PI3K, integrating cell survival mediators.

Mitochondria play a central role in the initiation of apoptosis, which is regulated by various factors such as ATP synthesis, reactive oxygen species, redox status, and outer membrane permeabilization. Disruption of chicken thioredoxin 2 (Trx2), a mitochondrial redox-regulating protein, results in apoptosis in DT40 cells. To investigate the mechanism of this apoptosis, we prepared transfectants expressing control (DT40-TRX2-/-), human thioredoxin 2 (TRX2) (DT40-hTRX2), or redox-inactive TRX2 (DT40-hTRX2CS) in conditional Trx2-deficient DT40 cells containing a tetracycline-repressible Trx2 gene. Production of ATP was not significantly changed by down-regulation of Trx2 expression. The generation of reactive oxygen species was enhanced by the down-regulation of Trx2 expression in DT40-TRX2-/-. Unexpectedly, the change was blocked in both DT40-hTRX2 and DT40-hTRX2CS cells. The down-regulation of Trx2 expression caused the release of cytochrome c and apoptosis-inducing factor on day 3, and apoptosis on day 5. These changes were also suppressed in both DT40-hTRX2 and DT40-hTRX2CS cells, suggesting that TRX2 regulates mitochondrial outer membrane permeabilization and apoptosis by redox-active site cysteine-independent mechanisms. The down-regulation of Trx2 expression caused a decrease in the protein level of Bcl-xL on day 3, whereas the protein level of Bcl-2 did not change until day 4, and the mRNA level of Bcl-xL was unchanged. The decrease in Bcl-xL was not blocked by a caspase 3 inhibitor but blocked in both DT40-hTRX2 and DT40-hTRX2CS. These findings indicate a link between the redox active site cysteine-independent action of TRX2 and the level of Bcl-xL in the regulation of apoptosis.

Transient cardiac ischemia activates cell survival signaling, conferring subsequent ischemia tolerance to the heart. This biological phenomenon, termed ischemic preconditioning, results in improved clinical outcome and attenuated infarct size following myocardial infarction. To explore genomic modifications underpinning this ischemia tolerance, we delineated the regulation and function of the cardiac enriched mitochondrial uncoupling proteins 2 and 3 during delayed ischemic preconditioning in the rat. Cardiac transcripts of genes encoding uncoupling proteins 2 and 3 are up-regulated in parallel with infarct size reduction in preconditioned hearts. Mitochondria isolated from preconditioned hearts exhibit an augmented inducible proton leak. In parallel, following anoxia-reoxygenation these mitochondria generate less hydrogen peroxide compared with non-preconditioned mitochondria. Preconditioning in rat cardiac derived myoblasts is abolished following uncoupling protein-2 depletion by RNA-interference. RNAi of uncoupling protein-3 partially attenuates the capacity to precondition these cells. Functional characterization of anoxia and reoxygenation tolerance following uncoupling protein 2 or 3 and combined 2 and 3 RNAi shows the largest reduction in viability follows depletion of both homologues. Uncoupling protein-2 depletion alone significantly attenuates anoxia-reoxygenation tolerance but uncoupling protein-3 depletion does not reduce anoxia tolerance. In parallel combined uncoupling protein depletion and isolated uncoupling protein-2 depletion augments ROS production in viable cardiomyocytes following anoxia-reoxygenation. Concurrent anti-oxidant administration ameliorates the uncoupling protein-depleted anoxia-susceptible phenotype. In conclusion, mitochondrial uncoupling proteins are necessary components of ischemia tolerance and function as components of the cellular antioxidant defense program. In the cytoprotective hierarchy, uncoupling protein-2 appears to play a greater role than uncoupling protein-3 in modulating ischemia/anoxia tolerance in heart-derived cells.

This study was designed to evaluate the effects of semen processing on the generation of intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in spermatozoa, and to develop reliable indexes for the evaluation of sperm quality during sperm preparation. Swim-up and density gradient centrifugation methods were used to separate semen in oligoasthenoteratozoospermia (OAT), leucocytospermia (LC) and normozoospermia groups. Levels of ROS and MMP were measured by flow cytometry. Before preparation, the patients with abnormal semen parameters had a lower MMP and higher ROS, and there was a negative correlation between MMP and ROS. The levels of MMP and ROS increased significantly, especially ROS produced by swim-up. A significant difference was found between the correlation of MMP and total normal motile sperm count after preparation in the OAT group. The level of ROS was associated with the amount of white blood cells in the LC group. The MMP can be used as an objective index to evaluate the sperm quality of OAT patients, and the combination of MMP and ROS can be used to assess the efficiency of sperm preparation in LC patients. These findings can guide selection of the ideal sperm separation technique for different sperm samples.

Higher levels of reactive oxygen species are associated with anergy in chronic lymphocytic leukemia2][3] As in other cells, mitochondria appear to be the main source of ROS and CLL cells have an increased mitochondrial mass compared to that of normal B cells. 2,4Higher levels of ROS confer increased sensitivity to induction of apoptosis by agents which further enhance ROS and it may be possible to exploit this as the basis for new treatments. 1,2,5]5,6 Analyses have mainly been performed on samples from patients with more advanced disease and, in that setting, prior therapy appeared to be a major determinant of ROS levels. 3,5,6This may reflect a direct effect of drugs on ROS production, perhaps linked to accumulation of mitochondrial DNA damage. 6However, a recent study demonstrated variable ROS levels in cells from untreated patients 2 indicating an influence of other factors.The B-cell receptor (BCR) is now recognized as a key determinant of variable behavior of CLL 7 and is a target for therapeutic attack.Antigen engagement appears to be iterative, with the outcome being either proliferation or anergy, a balance likely to influence disease outcome. 7,8Anergy

Emerging Designs of Aggregation-Induced Emission Agents for Enhanced Phototherapy Applications

Silibinin is an active constituent extracted from blessed milk thistle (Silybum marianum). Our previous study demonstrated that silibinin induced autophagy and apoptosis via reactive oxygen species (ROS) generation in HeLa cells. In this study, we investigated whether the autophagy- and apoptosis-associated molecules also involved in ROS generation. Silibinin promoted the expression phosphorylated-p53 (p-p53) in a dose-dependent manner. Pifithrin-α (PFT-α), a specific inhibitor of p53, reduced ROS production and reversed silibinin's growth-inhibitory effect. The ROS scavenger N-acetyl cysteine (NAC) attenuated silibinin-induced up-regulation of p-p53 expression, suggesting that p53 might be regulated by ROS and forms a positive feedback loop with ROS. On the other hand, silibinin dose-dependently promoted the expression of phosphorylated-c-Jun N-terminal kinase (p-JNK). Inhibition of JNK by SP600125 decreased ROS generation. NAC down-regulated the expression of p-JNK, indicating that JNK could be activated by ROS. Activation of p53 was suppressed by SP600125 and expression of p-JNK was inhibited by PFT-α, therefore silibinin might activate a ROS-JNK-p53 cycle to induce cell death. Silibinin up-regulated the PUMA and Bax expressions and down-regulated the mitochondrial membrane potential (MMP) level. PFT-α reduced the expression of PUMA and Bax. These results showed that p53 could interfere with mitochondrial functions such as MMP via PUMA pathways, thus resulting in ROS generation. In order to elucidate the functions of p53 in silibinin induced ROS generation, we have chosen the A431 cells (human epithelial carcinoma) because they lack p53 activity (p53His273 mutation). Interestingly, silibinin did not up-regulate the ROS level in A431 cells but lower the ROS level. PFT-α had no influence on ROS level in A431 cells. p53 activation plays a crucial role in silibinin induced ROS generation.

Increased seminal reactive oxygen species levels in patients with varicoceles correlate with varicocele grade but not with testis size