Dynamics of Immune Cell Microvilli.

Microvilli are actin-based microscopic membrane protrusions that are present in a wide variety of immune cells. Scanning electron microscopy (SEM) revealed that the T cell surface is covered by microvilli. Growing evidence shows that microvilli play important roles in T cell antigen detection and signal transduction. T cell microvilli are highly dynamic and constantly scan and palpate the opposing antigen-presenting cell (APC) surface in search of antigens. Visualizing the rapid movement of microvilli that are only hundreds of nanometers in size requires imaging technologies with high spatial and temporal resolution. Lattice light-sheet microscopy can achieve diffraction-limited resolution in all three dimensions with a temporal resolution of seconds, making it the perfect tool for studying dynamic events of microvilli during T cell antigen detection and activation. In this chapter, we describe a protocol for imaging localization and movement of T cell microvilli and surface receptors using lattice light-sheet microscopy.

Ginsenoside Re Attenuates Cisplatin-Induced Intestinal Toxicity via Suppressing GSK-3ß-Dependent Wnt/ß-Catenin Signaling Pathway In Vivo and In Vitro.

Previous reports have confirmed that crude saponins (ginsenosides) in Panax ginseng have a preventive effect on chemotherapy-induced intestinal injury. However, the protective effects and possible mechanisms of ginsenoside Re (G-Re, a maker saponin in ginseng) against chemotherapy-induced intestinal damage have not been thoroughly studied. In this work, a series of experiments in vivo and in vitro on the intestinal toxicity caused by cisplatin have been designed to verify the improvement effect of G-Re, focusing on the levels of Wnt3a and [Formula: see text]-catenin. Mice were intragastric with G-Re for 10 days, and intestinal injury was induced by intraperitoneal administration of cisplatin at a dose of 20 mg/kg. Histopathology, gastrointestinal digestive enzyme activities, inflammatory cytokines, and oxidative status were evaluated to investigate the protective effect. Furthermore, in IEC-6 cells, G-Re statistically reverses cisplatin-induced oxidative damage and cytotoxicity. The TUNEL and Hoechst 33258 staining demonstrated that G-Re possesses protective effects in cisplatin-induced apoptosis. Additionally, pretreatment with G-Re significantly alleviated the apoptosis via inhibition of over-expressions of B-associated X (Bax), as well as the caspase family members, such as caspase 3 and 9, respectively, in vivo and in vitro. Notably, western blotting results showed that G-Re treatment decreased Wnt3a, Glycogen synthase kinase [Formula: see text] (GSK-[Formula: see text]), and [Formula: see text]-catenin expression, suggesting that nuclear accumulation of [Formula: see text]-catenin was attenuated, thereby inhibiting the activation of GSK-[Formula: see text]-dependent Wnt/[Formula: see text]-catenin signaling, which was consistent with our expected results. Therefore, the above evidence suggested that G-Re may be a candidate drug for the treatment of intestinal injury.

Hyperstabilization of T cell microvilli contacts by chimeric antigen receptors.

T cells typically recognize their ligands using a defined cell biology-the scanning of their membrane microvilli (MV) to palpate their environment-while that same membrane scaffolds T cell receptors (TCRs) that can signal upon ligand binding. Chimeric antigen receptors (CARs) present both a therapeutic promise and a tractable means to study the interplay between receptor affinity, MV dynamics and T cell function. CARs are often built using single-chain variable fragments (scFvs) with far greater affinity than that of natural TCRs. We used high-resolution lattice lightsheet (LLS) and total internal reflection fluorescence (TIRF) imaging to visualize MV scanning in the context of variations in CAR design. This demonstrated that conventional CARs hyper-stabilized microvillar contacts relative to TCRs. Reducing receptor affinity, antigen density, and/or multiplicity of receptor binding sites normalized microvillar dynamics and synapse resolution, and effector functions improved with reduced affinity and/or antigen density, highlighting the importance of understanding the underlying cell biology when designing receptors for optimal antigen engagement.

Based on network pharmacology and molecular docking to explore the protective effect of Epimedii Folium extract on cisplatin-induced intestinal injury in mice.

Background: Epimedii Folium, as a natural botanical medicine, has been reported to have protective effects on intestinal diseases by modulating multiple signaling pathways. This study aimed to explore the potential targets and molecular mechanisms of Epimedii Folium extract (EFE) against cisplatin-induced intestinal injury through network pharmacology, molecular docking, and animal experiments. Methods: Network pharmacology was used to predict potential candidate targets and related signaling pathways. Molecular docking was used to simulate the interactions between significant potential candidate targets and active components. For experimental validation, mice were intraperitoneally injected with cisplatin 20 mg/kg to establish an intestinal injury model. EFE (100, 200 mg/kg) was administered to mice by gavage for 10 days. The protective effect of EFE on intestinal injury was analyzed through biochemical index detection, histopathological staining, and western blotting. Results: Network pharmacology analysis revealed that PI3K-Akt and apoptosis signaling pathways were thought to play critical roles in EFE treatment of the intestinal injury. Molecular docking results showed that the active constituents of Epimedii Folium, including Icariin, Epimedin A, Epimedin B, and Epimedin C, stably docked with the core AKT1, p53, TNF-α, and NF-κB. In verified experiments, EFE could protect the antioxidant defense system by increasing the levels of glutathione peroxidase (GSH-Px) and catalase (CAT) while reducing the content of malondialdehyde (MDA). EFE could also inhibit the expression of NF-κB and the secretion of inflammatory factors, including TNF-α, IL-1ß, and IL-6, thereby relieving the inflammatory damage. Further mechanism studies confirmed that EFE had an excellent protective effect on cisplatin-induced intestinal injury by regulating PI3K-Akt, caspase, and NF-κB signaling pathways. Conclusion: In summary, EFE could mitigate cisplatin-induced intestinal damage by modulating oxidative stress, inflammation, and apoptosis.

20(S)-ginsenoside Rh1 alleviates T2DM induced liver injury via the Akt/FOXO1 pathway.

Diabetes-associated liver injury becomes a dominant hepatopathy, leading to hepatic failure worldwide. The current study was designed to evaluate the ameliorative effects of ginsenoside Rh1 (G-Rh1) on liver injury induced by T2DM. A T2DM model was established using C57BL/6 mice through feeding with HFD followed by injection with streptozotocin at 100 mg·kg-1.. Then the mice were continuously administered with G-Rh1 (5 and 10 mg·kg-1), to explore the protective effects of G-Rh1 against liver injury. Results showed that G-Rh1 exerted significant effects on maintaining the levels of FBG and insulin, and ameliorated the increased levels of TG, TC and LDL-C induced by T2DM. Moreover, apoptosis in liver tissue was relieved by G-Rh1, according to histological analysis. Particularly, in diabetic mice, it was observed that not only the increased secretion of G6Pase and PEPCK in the gluconeogenesis pathway, but also inflammatory factors including NF-κB and NLRP3 were suppressed by G-Rh1 treatment. Furthermore, the underlying mechanisms by which G-Rh1 exhibited ameliorative effects was associated with its capacity to inhibit the activation of the Akt/FoxO1 signaling pathway induced by T2DM. Taken together, our preliminary study demonstrated the potential mechnism of G-Rh1 in protecting the liver against T2DM-induced damage.

T cells use distinct topographical and membrane receptor scanning strategies that individually coalesce during receptor recognition.

During immune surveillance, CD8 T cells scan the surface of antigen-presenting cells using dynamic microvillar palpation and movements as well as by having their receptors preconcentrated into patches. Here, we use real-time lattice light-sheet microscopy to demonstrate the independence of microvillar and membrane receptor patch scanning. While T cell receptor (TCR) patches can distribute to microvilli, they do so stochastically and not preferentially as for other receptors such as CD62L. The distinctness of TCR patch movement from microvillar movement extends to many other receptors that form patches that also scan independent of the TCR. An exception to this is the CD8 coreceptor which largely comigrates in patches that overlap with or are closely adjacent to those containing TCRs. Microvilli that assemble into a synapse contain various arrays of the engaged patches, notably of TCRs and the inhibitory receptor PD-1, creating a pastiche of occupancies that vary from microvillar contact to contact. In summary, this work demonstrates that localization of receptor patches within the membrane and on microvillar projections is random prior to antigen detection and that such random variation may play into the generation of many individually composed receptor patch compositions at a single synapse.

Spatiotemporal co-dependency between macrophages and exhausted CD8+ T cells in cancer.

T cell exhaustion is a major impediment to antitumor immunity. However, it remains elusive how other immune cells in the tumor microenvironment (TME) contribute to this dysfunctional state. Here, we show that the biology of tumor-associated macrophages (TAMs) and exhausted T cells (Tex) in the TME is extensively linked. We demonstrate that in vivo depletion of TAMs reduces exhaustion programs in tumor-infiltrating CD8+ T cells and reinvigorates their effector potential. Reciprocally, transcriptional and epigenetic profiling reveals that Tex express factors that actively recruit monocytes to the TME and shape their differentiation. Using lattice light sheet microscopy, we show that TAM and CD8+ T cells engage in unique, long-lasting, antigen-specific synaptic interactions that fail to activate T cells but prime them for exhaustion, which is then accelerated in hypoxic conditions. Spatially resolved sequencing supports a spatiotemporal self-enforcing positive feedback circuit that is aligned to protect rather than destroy a tumor.

Maltol mitigates cisplatin-evoked cardiotoxicity via inhibiting the PI3K/Akt signaling pathway in rodents in vivo and in vitro.

Our current research aims to evaluate the efficiency of a flavor enhancer, maltol (produced by heating ginseng) against cisplatin-evoked cardiotoxicity by establishing cisplatin-induced heart injury in vivo and H9C2 rat cardiomyocyte model. The cisplatin-treated mice at 3 mg/kg for four times on the 7th, 9th, 11th and 13th day, and in them appeared a serious cardiac damage accompanied with the increase in indicators of heart damage. Multiple exposure of 3 mg/kg for four times of cisplatin increased cardiac cells apoptosis with increased expression of Bax and cleaved-caspase 3, and decreased expression of Bcl-2. Interestingly, supplement of maltol at doses of 50 and 100 mg/kg for 15 days significantly suppressed the cardiac disturbance. In cultured H9C2 cells, maltol enhanced PI3K/Akt expression level during cisplatin treatment, and reduced cisplatin-induced apoptosis. Notably, inhibition of PI3K/Akt by LY294002 and HY-10249A lessened the efficacy of maltol. In mice, maltol apparently induced PI3K/Akt in heart tissues and protected against cisplatin-induced cardiotoxicity. In conclusion, maltol exerted the protective effects against cisplatin-induced cardiotoxicity, at least partially by inhibiting the activation of PI3K/Akt signaling pathways in cardiomyocytes, to ease oxidative stress, and alleviate reactive oxygen species-mediated apoptosis.

Arctigenin Triggers Apoptosis and Autophagy via PI3K/Akt/mTOR Inhibition in PC-3M Cells.

Arctigenin (ARG), a natural lignans compound isolated from Arctium lappa L. In this study, the anti-tumor effect of ARG on prostate cancer cell PC-3M and the mechanism of apoptosis and autophagy induced by phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway were discussed, and further confirmed by the joint treatment of ARG and PI3K inhibitor LY294002. Here, the effect of ARG on cell viability was evaluated in PC-3M cells by Cell Counting Kit-8 reagent (CCK-8) assay. After the treatment of ARG, colony formation assay was used to detect the anti-proliferation effect. Annexin V-fluoresceine isothiocyanate/propidium iodide (FITC/PI) kit and 4',6-diamidino-2-phenylindole (DAPI) staining were used to detect the apoptosis level, and cell cycle changes were analyzed by flow cytometry. The expression of autophagy was detected by acridine orange staining. In addition, the expression levels of apoptosis and autophagy-related proteins were analyzed by Western blot. The result showed that different concentrations of ARG inhibited the proliferation of PC-3M cells. DAPI staining and flow cytometry showed that ARG induced PC-3M cell apoptosis and arrested cell in G0/G1 phase. Acridine orange staining showed that ARG induced autophagy in PC-3M cells. Western blot experiments showed that ARG inhibited the expression of Bcl-2, promoted the expression of Bax and cleaved caspase-3. At the same time, the expression of autophagy-related proteins LC3B-II and Beclin-1 increased after ARG treatment, but P62 decreased. In addition, further studies have shown that treatment with LY294002 enhanced the effects of ARG on the expression of proteins associated with apoptosis and autophagy, indicating that ARG may induce apoptosis and autophagy through PI3K/Akt/mTOR pathway.

Visualizing Synaptic Transfer of Tumor Antigens among Dendritic Cells.

Generation of tumor-infiltrating lymphocytes begins when tumor antigens reach the lymph node (LN) to stimulate T cells, yet we know little of how tumor material is disseminated among the large variety of antigen-presenting dendritic cell (DC) subsets in the LN. Here, we demonstrate that tumor proteins are carried to the LN within discrete vesicles inside DCs and are then transferred among DC subsets. A synapse is formed between interacting DCs and vesicle transfer takes place in the absence of free exosomes. DCs -containing vesicles can uniquely activate T cells, whereas DCs lacking them do not. Understanding this restricted sharing of tumor identity provides substantial room for engineering better anti-tumor immunity.

Study on the Changes of Chemical Constituents in Different Compatibilities of Ginseng-Prepared Rehmannia Root and Their Effects on Bone Marrow Inhibition after Chemotherapy.

Ginseng (G) and Prepared Rehmannia Root (PRR) are commonly used in traditional Chinese medicine for blood supplementation. This study aimed to study G and PRR with different compatibility ratios changes in chemical composition and inhibition of cyclophosphamide-induced myelosuppression. HPLC was used to determine the chemical constituents of 13 ginsenosides, 5-hydroxymethylfurfural (5-HMF) and verbascoside in different proportions of G-PRR. Balb/c mice were injected intraperitoneally with cyclophosphamide (CTX) to induce bone marrow suppression. The effects of different proportions of G-PRR on peripheral blood, bone marrow nucleated cells, thymus and spleen index of myelosuppressed mice were analyzed. The results showed that the compatibility of G and PRR can promote the dissolution of ginsenosides, and the content of conventional ginsenosides decreased, and the content of rare ginsenosides increased. Different proportions of G-PRR increased the number of peripheral blood and bone marrow nucleated cells in cyclophosphamide-induced bone marrow suppression mice (p < 0.01), increased thymus index (p < 0.01), decreased spleen index (p < 0.01). Different proportions of G-PRR can improve the myelosuppression induced by cyclophosphamide in mice, and the combined effect of G-PRR is better than the single decoction of G and PRR. Among them, G-PRR 2 : 3 and G-PRR 1 : 2 were better than the other groups. These results indicate that different proportion of G-PRR can improve bone marrow suppression, and the combined decoction of G-PRR is better than the separate Decoction in improving bone marrow suppression. This improvement may be related to the changes of the substance basis and active ingredients of G-PRR.

[Analysis of parameters of serum concentration and pharmacokinetic of liposome and aqueous solution of toatal ginsenoside of ginseng stems and leaves in rats].

The experiment was aimed to investigate the difference of plasma concentration and pharmacokinetic parameters between liposome and aqueous solution of toatal ginsenoside of ginseng stems and leaves in rats, such as ginsenosides Rg1, Re, Rf, Rb1, Rg2, Rc, Rb2, Rb3, Rd. After intravenous injection of liposome and aqueous solution in rats, the blood was taken from the femoral vein to detect the plasma concentration of the above 9 ginsenoside monomers in different time points by using HPLC. The concentration-time curve was obtained and 3p97 pharmacokinetic software was used to get the pharmacokinetic parameters. After the intravenous injection of ginsenosides to rats, nine ginsenosides were detected in plasma. In general, among these ginsenosides, the peak time of the aqueous solution was between 0.05 to 0.083 3 h, and the serum concentration peak of liposome usually appeared after 0.5 h. After software fitting, the aqueous solution of ginsenoside monomers Rg1, Re, Rf, Rg2, Rc, Rd, Rb3 was two-compartment model, and the liposomes were one-compartment model; aqueous solution and liposome of ginsenoside monomers Rb1 were three-compartment model; aqueous solution of ginsenoside monomers Rb2 was three-compartment model, and its liposome was one-compartment model. Area under the drug time curve (AUC) of these 9 kinds of saponin liposomes was larger than that of aqueous solution, and the retention time of the liposomes was longer than that of the aqueous solution; the removal rate was slower than that of the aqueous solution, and the half-life was longer than that of the water solution. The results from the experiment showed that by intravenous administration, the pharmacokinetic parameters of two formulations were significantly different from each other; the liposomes could not only remain the drug for a longer time in vivo, but also reduce the elimination rate and increase the treatment efficacy. As compared with the traditional dosage forms, the total ginsenoside of ginseng stems and leaves can improve the sustained release of the drug, which is of great significance for the research and development of new dosage forms of ginsenosides in the future.

Super-resolution imaging of synaptic and Extra-synaptic AMPA receptors with different-sized fluorescent probes.

Previous studies tracking AMPA receptor (AMPAR) diffusion at synapses observed a large mobile extrasynaptic AMPAR pool. Using super-resolution microscopy, we examined how fluorophore size and photostability affected AMPAR trafficking outside of, and within, post-synaptic densities (PSDs) from rats. Organic fluorescent dyes (≈4 nm), quantum dots, either small (≈10 nm diameter; sQDs) or big (>20 nm; bQDs), were coupled to AMPARs via different-sized linkers. We find that >90% of AMPARs labeled with fluorescent dyes or sQDs were diffusing in confined nanodomains in PSDs, which were stable for 15 min or longer. Less than 10% of sQD-AMPARs were extrasynaptic and highly mobile. In contrast, 5-10% of bQD-AMPARs were in PSDs and 90-95% were extrasynaptic as previously observed. Contrary to the hypothesis that AMPAR entry is limited by the occupancy of open PSD 'slots', our findings suggest that AMPARs rapidly enter stable 'nanodomains' in PSDs with lifetime >15 min, and do not accumulate in extrasynaptic membranes.

Visualizing dynamic microvillar search and stabilization during ligand detection by T cells.

During immune surveillance, T cells survey the surface of antigen-presenting cells. In searching for peptide-loaded major histocompatibility complexes (pMHCs), they must solve a classic trade-off between speed and sensitivity. It has long been supposed that microvilli on T cells act as sensory organs to enable search, but their strategy has been unknown. We used lattice light-sheet and quantum dot-enabled synaptic contact mapping microscopy to show that anomalous diffusion and fractal organization of microvilli survey the majority of opposing surfaces within 1 minute. Individual dwell times were long enough to discriminate pMHC half-lives and T cell receptor (TCR) accumulation selectively stabilized microvilli. Stabilization was independent of tyrosine kinase signaling and the actin cytoskeleton, suggesting selection for avid TCR microclusters. This work defines the efficient cellular search process against which ligand detection takes place.

The Synthesis and Evaluation of Arctigenin Amino Acid Ester Derivatives.

The use of arctigenin (ARG), a traditional medicine with many pharmacological activities, has been restricted due to its poor solubility in water. Five amino acid derivatives of ARG have been synthesized using glycine, o-alanine, valine, leucine, and isoleucine, which have t-butyloxy carbonyl (BOC) as a protective group. In this study, we examined the effects of removing these protective groups. The results showed that the amino acid derivatives have better solubility and nitrite-clearing ability than ARG. Among the compounds tested, the amino acid derivatives without protective group were the best. Based on these results, ARG and its two amino acid derivatives without protective group (ARG8, ARG10) were selected to evaluate their anti-tumor activity in vivo at a dosage of 40 mg/kg. The results indicated that ARG8 and ARG10 both exhibit more anti-tumor activity than ARG in H22 tumor-bearing mice. The tumor inhibition rates of ARG8 and ARG10 were 69.27 and 43.58%, which was much higher than ARG. Furthermore, the mice treated with these compounds exhibited less damage to the liver, kidney and immune organs compared with the positive group. Furthermore, ARG8 and ARG10 improved the serum cytokine levels significantly compared to ARG. In brief, this study provides a method to improve the water solubility of drugs, and we also provide a reference basis for new drug development.

[Research on quality changes in ginseng stems and leaves before and after frost].

The present study is to investigate the quality changes of ginseng stems and leaves before and after frost. The contents changes of ginsenoside, free amino acid, and total phenolic compounds, as well as DPPH radical scavenging effect before and after frost were measured. The content of 9 ginsenoside monomer in ginseng stems was decreased except for Rg, and Re after frost, but in ginseng leaves was all decreased. The total content of amino acids was decreased in ginseng stems after frost, while increased in ginseng leaves. The content of phenolic compounds in ginseng stems and leaves were both decreased after frost while the ability of DPPH radical scavenging was improved. The factor of frost has great impact on the quality of ginseng stems and leaves.

Small quantum dots conjugated to nanobodies as immunofluorescence probes for nanometric microscopy.

Immunofluorescence, a powerful technique to detect specific targets using fluorescently labeled antibodies, has been widely used in both scientific research and clinical diagnostics. The probes should be made with small antibodies and high brightness. We conjugated GFP binding protein (GBP) nanobodies, small single-chain antibodies from llamas, with new ∼7 nm quantum dots. These provide simple and versatile immunofluorescence nanoprobes with nanometer accuracy and resolution. Using the new probes we tracked the walking of individual kinesin motors and measured their 8 nm step sizes; we tracked Piezo1 channels, which are eukaryotic mechanosensitive channels; we also tracked AMPA receptors on living neurons. Finally, we used a new super-resolution algorithm based on blinking of (small) quantum dots that allowed ∼2 nm precision.

Fluorescence imaging with one-nanometer accuracy (FIONA).

Fluorescence imaging with one-nanometer accuracy (FIONA) is a simple but useful technique for localizing single fluorophores with nanometer precision in the x-y plane. Here a summary of the FIONA technique is reported and examples of research that have been performed using FIONA are briefly described. First, how to set up the required equipment for FIONA experiments, i.e., a total internal reflection fluorescence microscopy (TIRFM), with details on aligning the optics, is described. Then how to carry out a simple FIONA experiment on localizing immobilized Cy3-DNA single molecules using appropriate protocols, followed by the use of FIONA to measure the 36 nm step size of a single truncated myosin Va motor labeled with a quantum dot, is illustrated. Lastly, recent effort to extend the application of FIONA to thick samples is reported. It is shown that, using a water immersion objective and quantum dots soaked deep in sol-gels and rabbit eye corneas (>200 µm), localization precision of 2-3 nm can be achieved.

Stable small quantum dots for synaptic receptor tracking on live neurons.

We developed a coating method to produce functionalized small quantum dots (sQDs), about 9 nm in diameter, that were stable for over a month. We made sQDs in four emission wavelengths, from 527 to 655 nm and with different functional groups. AMPA receptors on live neurons were labeled with sQDs and postsynaptic density proteins were visualized with super-resolution microscopy. Their diffusion behavior indicates that sQDs access the synaptic clefts significantly more often than commercial QDs.