TLR4 sensitizes plasmacytoid dendritic cells for antiviral response against SARS-CoV-2 coronavirus.

Plasmacytoid dendritic cells are a rare subset of dendritic cells that exhibit antiviral functions in response to toll-like receptor 7/8 stimulations. Alternative toll-like receptors such as TLR4 have been known to be active in plasmacytoid dendritic cells for immune regulatory functions. However, it is unclear whether these toll-like receptors differentially activate plasmacytoid dendritic cells as compared with canonical toll-like receptor 7/8 stimulation. Here, we assessed alternative plasmacytoid dendritic cell activation states mediated by toll-like receptors other than endosomal toll-like receptors via the RNA sequencing approach. We found that toll-like receptor 4 stimulation induced a high degree of similarity in gene expression pattern to toll-like receptor 7/8 stimulation in plasmacytoid dendritic cells. Despite high resemblance to toll-like receptor 7/8, we discovered unique genes that were activated under toll-like receptor 4 activation only, as well as genes that were induced at a higher magnitude in comparison to toll-like receptor 7/8 activation. In comparison between toll-like receptor 4-activated plasmacytoid dendritic cells and conventional dendritic cells, we revealed that plasmacytoid dendritic cells and conventional dendritic cells expressed distinct gene sets, whereby conventional dendritic cells mostly favored antigen presentation functions for adaptive immune response regulation while plasmacytoid dendritic cells leaned toward immune response against infectious diseases. Last, we determined that toll-like receptor 4 activation sensitized plasmacytoid dendritic cells against SARS-CoV-2 (COVID-19) single-stranded RNA by enhancing antiviral-related responses and type I interferon production. These findings provided greater insights into the toll-like receptor 4 activation state in plasmacytoid dendritic cells, which can be beneficial for alternative therapeutic interventions involving plasmacytoid dendritic cells for various diseases.

Antileishmanial anthraquinones from the rhyzomes of Rumex abyssinicus Jacq (Polygonaceae).

Phytochemical investigation of the rhyzomes of Rumex abyssinicus (Polygonaceae) afforded six anthraquinones viz chrysophanol (1), physcion (2), emodin (3), mixture of physcion-8-O-ß,D-glucopyranoside (4) and chrypsophanol-8-O-ß,D-glucopyranoside (5), and emodin-8-O-ß,D-glucopyranoside (6). All the compounds were characterised and identified by comparison of their MS and NMR data with available literature data. The isolated compounds were evaluated for their antileishmanial activity. Emodin (3) was the most active compounds with IC50 13.82 and 0.26 µg/mL against Leishmania donovani amastigotes and promastigotes, respectively. Emodin-8-O-ß,D-glucopyranoside (6) also showed a moderate activity with IC50 27.53 and 37.08 µg/mL. This is the first report of antileishmanial compounds from R. abyssinicus and the antileishmanial activities of compounds 2, 4, 5 and 6 are here reported for the first time.

An Immunological Perspective of Circulating Tumor Cells as Diagnostic Biomarkers and Therapeutic Targets.

Immune modulation is a hallmark of cancer. Cancer-immune interaction shapes the course of disease progression at every step of tumorigenesis, including metastasis, of which circulating tumor cells (CTCs) are regarded as an indicator. These CTCs are a heterogeneous population of tumor cells that have disseminated from the tumor into circulation. They have been increasingly studied in recent years due to their importance in diagnosis, prognosis, and monitoring of treatment response. Ample evidence demonstrates that CTCs interact with immune cells in circulation, where they must evade immune surveillance or modulate immune response. The interaction between CTCs and the immune system is emerging as a critical point by which CTCs facilitate metastatic progression. Understanding the complex crosstalk between the two may provide a basis for devising new diagnostic and treatment strategies. In this review, we will discuss the current understanding of CTCs and the complex immune-CTC interactions. We also present novel options in clinical interventions, targeting the immune-CTC interfaces, and provide some suggestions on future research directions.

Anti-plasmodial, Cytotoxic and Antioxidant Activities of Selected Ghanaian Medicinal Plants.

Malaria affects about half of the world's population. The sub-Saharan African region is the most affected. Plant natural products have been a major source of antimalarial drugs; the first (quinine) and present (artemisinin) antimalarials are of natural product origin. Some secondary metabolites demonstrate adjuvant antioxidant effects and selective activity. The focus of this study was to investigate the anti-plasmodial activity, cytotoxicities and antioxidant properties of eight (8) Ghanaian medicinal plants. The anti-plasmodial activity was determined using the SYBR green assay and the tetrazolium-based colorimetric assay (MTT) was employed to assess cytotoxicity of extracts to human RBCs and HL-60 cells. Antioxidant potential of plant extracts was evaluated using Folin-Ciocalteu and superoxide dismutase assays. Phytochemical contstituents of the plant extracts were also assessed. All the extracts demonstrated anti-plasmodial activities at concentrations <50 µg/ml. Parkia clappertoniana and Terminalia ivorensis elicited the strongest anti-plasmodial activities with 50% inhibitory concentrations (IC50) of 1.13 µg/ml and 0.95 µg/ml, respectively. This is the first report on anti-plasmodial activities of Baphia nitida, Tabernaemontana crassa and Treculia Africana. T. Africana showed moderate anti-plasmodial activity with IC50 value of 6.62 µg/mL. Extracts of P. clappertoniana, T. Africana and T. ivorensis (0.4 mg/mL) showed >50% antioxidant effect (SOD). The extracts were not cytotoxicity towards RBCs at the concentration tested (200 µg/ml) but were weakly cytotoxic to HL-60 cell. Selectivity indices of most of the extracts were greater than 10. Our results suggest that most of the plant extracts have strong anti-plasmodial activity and antioxidant activity which warrants further investigations.

Antiproliferative Activities of Methanolic Extract and Fractions of Tetrapleura Tetraptera Fruit.

Most of the current cancer chemotherapeutics are associated with harsh and undesirable side effects, including toxicity and chemoresistance, driving the need for safer and more effective alternatives. In this study, the antiproliferative activities of the methanolic extract of Tetrapleura tetraptera fruits and nine different fractions (C1-C9) from the column chromatographic separation of the extract against leukemia (Jurkat) and human breast cancer (MCF-7) cell lines were investigated using a tetrazolium-based colorimetric assay. Phytochemical screening of the extract and fractions found alkaloids, carbohydrates, flavonoids, glycosides, phenols, saponins, steroids, tannins, and terpenoids in the methanolic extract. Most of the fractions exhibited antiproliferative activity (>100 µg/mL) with the Jurkat cells being more susceptible than the MCF-7 cells. Four of the collected fractions C4, C3, C5, and C2 had good selective indices in decreasing order of activity, in the case of Jurkat cells. Liquid chromatography-mass spectrometry analysis of all samples (except for C4 and C9) revealed that C1, C2, C3, and C5 each had a single component. More importantly, fractions C2, C3, and C5, which were selective to Jurkat cells, also had the same retention time of 1.846 min. Fractions C6 and C8 had two components, with C7 having four components. This study serves as a basis for further work to isolate and characterize potential anticancer agents from the fractions of extracts of T. tetraptera fruits.

Antileishmanial and cytotoxic activities of a new limonoid and a new phenyl alkene from the stem bark of Trichilia gilgiana (Meliaceae).

One new limonoid, trigilgianin (1), one new phenyl alkene, epoxy gilgialkene (2), together with five known compounds: scopoletin (3), sitosteryl-6'-O-undecanoate-ß-D-glucoside (4), sitosteryl-O-ß-D-glucopyranoside (5), cinchonain A (6) and cinchonain B (7) were isolated from the stem bark of Trichilia gilgiana Harms. (Meliaceae). All compounds were isolated for the first time from this species. The structures were elucidated on the basis of spectral studies and by comparison of these data with those from the literature. Compounds 1, 2, 3, 6 and 7 were tested for in vitro antileishmanial activity against visceral leishmaniasis parasite Leishmania donovani and cytotoxicity against macrophage RAW 264.7 cell line. Compounds 1 and 3 showed the highest antileishmanial activity (IC50 values of 6.044 and 6.804 µg/mL, respectively) with low cytotoxicity (CC50 values of >200 and 47.47 µg/mL, respectively), while compound 2 was moderately active on L. donovani promastigotes (IC50 56.81 µg/mL).

In Vitro Antioxidant Potential and Effect of a Glutathione-Enhancer Dietary Supplement on Selected Rat Liver Cytochrome P450 Enzyme Activity.

BACKGROUND: There is considerable evidence that many people take dietary supplements including those of herbal origin as an alternative therapy to improve their health. One such supplement, with an amalgam of constituents, is CellGevity®. However, the effect of this dietary supplement on drug-metabolizing enzymes is poorly understood, as it has not been studied extensively. Therefore, we investigated the effect of CellGevity dietary supplement on selected rat liver microsomal cytochrome P450 (CYP) enzymes, the most common drug-metabolizing enzymes. We also determined the total antioxidant potential of this dietary supplement in vitro. METHODS: To determine the antioxidant potential of CellGevity dietary supplement, 2,2-diphenyl-2-picryl-hydrazyl (DPPH), total phenolic, and flavonoid assays were used after initial preparation of a solution form of the supplement (low dose, LD; 4 mg/kg and high dose, HD; 8 mg/kg). Rats received oral administration of these doses of the supplement for 7 days, after which the effect of the supplement on selected liver CYP enzymes was assessed using probe substrates and spectroscopic and high-performance liquid chromatographic methods. Rats which received daily administration of 80 mg/kg of phenobarbitone and distilled water served as positive and negative controls, respectively. RESULTS: The IC50 value of the supplement 0.34 ± 0.07 mg/ml compared to 0.076 ± 0.03 mg/ml of the BHT (positive control). The total phenolic content of the supplement at a concentration of 2.5 mg/ml was 34.97 g gallic acid equivalent (GAE)/100 g while its total flavonoid content at a concentration of 2.5 mg/ml was 6 g quercetin equivalent (QE)/100 g. The supplement significantly inhibited rat CYP2B1/2B2 (LDT 92.4%; HDT 100%), CYP3A4 (LDT 81.2%; HDT 71.7%), and CYP2C9 (LDT 21.7%; HDT 28.5%) while it had no significant inhibitory effect on CYPs 1A1/1A2, CYP1A2, and CYP2D6. CONCLUSION: CellGevity dietary supplement possesses moderate antioxidant activity in vitro and has an inhibitory effect on selected rat liver CYP enzymes, suggesting its potential interaction with drugs metabolized by CYP enzymes.

Isolation of colorectal cancer stem-like cells.

This study is aimed at isolating colorectal cancer stem-like cells in vitro using a neurosphere assay method employed in isolating gliobastoma multiforme tumor cells. This was followed with confirmation of the isolated cells by flow cytometry, pluripotent genes expression and in vivo tumorigenicity assay. Using this culture assay, stem-like and non-stem-like CRC cells were isolated and expanded in vitro from purchased Balb/c mice induced with CT26 colorectal cancer (CRC) cell line. The procedure includes an initial mechanical dissociation and chemical digestion of tumor tissue and subsequently plating the resulting single cell suspension in serum-free medium (SFM) or serum-containing medium (SCM). This selectively permits growth of cancer stem-like cells in SFM and eliminates non-stem-like cancer cells through the process of anoikis or apoptosis. CRC stem cells derived cultures proliferated as non-adherent spheres in vitro in different shapes and sizes. These cells expressed cell surface markers previously reported for tumor stem cells, including CD44, CD133, CD166 and CD26 and formed tumors when implanted in severe combined immunodeficient mice in a concentration dependent manner. Importantly, the stem-like cells had self-renewal properties with significantly higher expression of the pluripotent stem cell genes NANOG, OCT4, and SOX2 compared to the adherent non-stem cells. Collectively, the results of this study indicate that SFM is a defined culture medium that enriches for CRC stem-like cells and represents a suitable in vitro model for the study of CRC stem-like cells. This finding may be useful in developing therapeutic strategies aimed at eradicating the tumorigenic subpopulation within colorectal cancer.

Reduction in the urinary aflatoxin M1 biomarker as an early indicator of the efficacy of dietary interventions to reduce exposure to aflatoxins.

Aflatoxin B1 is a persistent public health issue in Ghana. Assessment of AFB1 intervention efficacy is currently dependent on long-term biomarkers. This study was designed to determine whether daily AFM1 biomarker levels could be utilized as an early detection method for intervention efficacy. Participants were treated with a refined calcium montmorillonite clay (UPSN) or a placebo (calcium carbonate) in a crossover study. Urine samples were assessed for AFM1 levels daily. UPSN treatment reduced AFM1 biomarkers by 55% compared to the placebo. This is the first study to show that daily urinary AFM1 levels can be used as a biomarker of internal aflatoxin B1 exposure in short-term intervention trials to determine efficacy.