Dioscorin isolated from Dioscorea alata activates TLR4-signaling pathways and induces cytokine expression in macrophages

Andrographolide suppresses the malignancy of pancreatic cancer via alleviating DNMT3B-dependent repression of tumor suppressor gene ZNF382

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer type that urgently requires effective therapeutic strategies. Andrographolide, a labdane diterpenoid compound abundant in Andrographis paniculata, has anticancer effects against various cancer types, but its anticancer activity and mechanism against PDAC remain largely uncharacterized.

PURPOSE

This study explores novel drug target(s) and underlying molecular mechanism of andrographolide against PDAC.

STUDY DESIGN AND METHODS

The malignant phenotypes of PDAC cells, PANC-1 and MIA PaCa-2 cells, were measured using MTT, clonogenic assays, and Transwell migration assays. A PDAC xenograft animal model was used to evaluate tumor growth in vivo. Western blot, immunofluorescence and immunohistochemistry were used for measuring protein expression. The TCGA database was analyzed to evaluate promoter methylation status, gene expression, and their relationship with patient survival rates. RT-qPCR was used for detecting mRNA expression. Reporter assays were used for detecting signal transduction pathways. Promoter DNA methylation was determined by sodium bisulfite treatment and methylation-specific PCR (MSP). The biological function and role of specific genes involved in drug effects were measured through gene overexpression.

RESULTS

Andrographolide treatment suppressed the proliferation and migration of PDAC cells and impaired tumor growth in vivo. Furthermore, andrographolide induced the mRNA and protein expression of zinc finger protein 382 (ZNF382) in PDAC cells. Overexpression of ZNF382 inhibited malignant phenotypes and cancer-associated signaling pathways (AP-1, NF-κB and β-catenin) and oncogenes (ZEB-1, STAT-3, STAT-5, and HIF-1α). Overexpression of ZNF382 delayed growth of PANC-1 cells in vivo. ZNF382 mRNA and protein expression was lower in tumor tissues than in adjacent normal tissues of pancreatic cancer patients. Analysis of the TCGA database found the ZNF382 promoter is hypermethylated in primary pancreatic tumors which correlates with its low expression. Furthermore, andrographolide inhibited the expression of DNA methyltransferase 3 beta (DNMT3B) and increased the demethylation of the ZNF382 promoter in PDAC cells. Overexpression of DNMT3B attenuated the andrographolide-suppressed proliferation and migration of PDAC cells.

CONCLUSION

Our finding revealed that ZNF382 acts as a tumor suppressor gene in pancreatic cancer and andrographolide restores ZNF382 expression to suppress pancreatic cancer, providing a novel molecular target and a promising therapeutic approach for treating pancreatic cancer.

Galgravin Isolated from Piper kadsura Ameliorates Lipopolysaccharide (LPS)-Induced Endotoxemia in Mice

Sepsis results from uncontrolled inflammation, characterized by cytokine storm and immunoparalysis. To assess whether galgravin, a natural lignan isolated from Piper kadsura, can be used to treat sepsis, models of bacterial lipopolysaccharide (LPS)-activated macrophages and LPS-induced endotoxemia mice were used. Galgravin suppressed NF-κB activation in LPS-activated RAW 264.7 macrophages without causing significant cytotoxicity, in which proinflammatory molecules like TNF-α, IL-6, iNOS, and COX-2 were downregulated. In addition, the expression of TNF-α and IL-6 was also suppressed by galgravin in LPS-activated murine bone marrow-derived macrophages. Moreover, galgravin significantly downregulated the mRNA expression of TNF-α, IL-6, and iNOS in the lungs and decreased TNF-α and IL-6 in the serum and IL-6 in the bronchoalveolar lavage fluid of LPS-challenged mice. The COX-2 expression in tissues, including the lung, liver, and kidney, as well as the lung alveolar hemorrhage, was also reduced by galgravin. The present study reveals the anti-inflammatory effects of galgravin in mouse models and implies its potential application in inflammation diseases.

Andrographolide suppresses the malignancy of triple-negative breast cancer by reducing THOC1-promoted cancer stem cell characteristics

Triple-negative breast cancers (TNBCs) are difficult to cure and currently lack of effective treatment strategies. Cancer stem cells (CSCs) are highly associated with the poor clinical outcome of TNBCs. Thoc1 is a core component of the THO complex (THOC) that regulates the elongation, processing and nuclear export of mRNA. The function of thoc1 in TNBC and whether Thoc1 serves as a drug target are poorly understood. In this study, we demonstrated that thoc1 expression is elevated in TNBC cell lines and human TNBC patient tissues. Knockdown of thoc1 decreased cancer stem cell populations, reduced mammosphere formation, impaired THOC function, and downregulated the expression of stemness-related proteins. Moreover, the thoc1-knockdown 4T1 cells showed less lung metastasis in an orthotopic breast cancer mouse model. Overexpression of Thoc1 promoted TNBC malignancy and the mRNA export of stemness-related genes. Furthermore, treatment of TNBC cells with the natural compound andrographolide reduced the expression of Thoc1 expression, impaired homeostasis of THOC, suppressed CSC properties, and delayed tumor growth in a 4T1-implanted orthotopic mouse model. Andrographolide also reduced the activity of NF-κB, an upstream transcriptional regulator of Thoc1. Notably, thoc1 overexpression attenuates andrographolide-suppressed cellular proliferation. Altogether, our results demonstrate that THOC1 promotes cancer stem cell characteristics of TNBC, and andrographolide is a potential natural compound for eliminating CSCs of TNBCs by downregulating the NF-κB-thoc1 axis.

West African medicinal plants and their constituent compounds as treatments for viral infections, including SARS-CoV-2/COVID-19

OBJECTIVES

The recent emergence of the COVID-19 pandemic (caused by SARS-CoV-2) and the experience of its unprecedented alarming toll on humanity have shone a fresh spotlight on the weakness of global preparedness for pandemics, significant health inequalities, and the fragility of healthcare systems in certain regions of the world. It is imperative to identify effective drug treatments for COVID-19. Therefore, the objective of this review is to present a unique and contextualised collection of antiviral natural plants or remedies from the West African sub-region as existing or potential treatments for viral infections, including COVID-19, with emphasis on their mechanisms of action.

EVIDENCE ACQUISITION

Evidence was synthesised from the literature using appropriate keywords as search terms within scientific databases such as Scopus, PubMed, Web of Science and Google Scholar.

RESULTS

While some vaccines and small-molecule drugs are now available to combat COVID-19, access to these therapeutic entities in many countries is still quite limited. In addition, significant aspects of the symptomatology, pathophysiology and long-term prognosis of the infection yet remain unknown. The existing therapeutic armamentarium, therefore, requires significant expansion. There is evidence that natural products with antiviral effects have been used in successfully managing COVID-19 symptoms and could be developed as anti-COVID-19 agents which act through host- and virus-based molecular targets.

CONCLUSION

Natural products could be successfully exploited for treating viral infections/diseases, including COVID-19. Strengthening natural products research capacity in developing countries is, therefore, a key strategy for reducing health inequalities, improving global health, and enhancing preparedness for future pandemics.

Understanding immune-modulatory efficacy in vitro

Boosting or suppressing our immune system represents an attractive adjunct in the treatment of infections including SARS-CoV-2, cancer, AIDS, malnutrition, age related problems and some inflammatory disorders. Thus, there has been a growing interest in exploring and developing novel drugs, natural or synthetic, that can manipulate our defence mechanism. Many of such studies, reported till date, have been designed to explore effect of the therapeutic on function of macrophages, being a key component in innate immune system. Indeed, RAW264.7, J774A.1, THP-1 and U937 cell lines act as ideal model systems for preliminary investigation and selection of dose for in vivo studies. Several bioassays have been standardized so far where many techniques require high throughput instruments, cost effective reagents and technical assistance that may hinder many scholars to perform a method demanding compilation of available protocols. In this review, we have taken an attempt for the first time to congregate commonly used in vitro immune-modulating techniques explaining their principles. The study detected that among about 40 different assays and more than 150 sets of primers, the methods of cell proliferation by MTT, phagocytosis by neutral red, NO detection by Griess reaction and estimation of expression of TLRs, COX-2, iNOS, TNF-α, IL-6 and IL-1β by PCR have been the most widely used to screen the therapeutics under investigation.

Birch Pollen Induces Toll-Like Receptor 4-Dependent Dendritic Cell Activation Favoring T Cell Responses

Seasonal exposure to birch pollen (BP) is a major cause of pollinosis. The specific role of Toll-like receptor 4 (TLR4) in BP-induced allergic inflammation and the identification of key factors in birch pollen extracts (BPE) initiating this process remain to be explored. This study aimed to examine (i) the importance of TLR4 for dendritic cell (DC) activation by BPE, (ii) the extent of the contribution of BPE-derived lipopolysaccharide (LPS) and other potential TLR4 adjuvant(s) in BPE, and (iii) the relevance of the TLR4-dependent activation of BPE-stimulated DCs in the initiation of an adaptive immune response. In vitro, activation of murine bone marrow-derived DCs (BMDCs) and human monocyte-derived DCs by BPE or the equivalent LPS (nLPS) was analyzed by flow cytometry. Polymyxin B (PMB), a TLR4 antagonist and TLR4-deficient BMDCs were used to investigate the TLR4 signaling in DC activation. The immunostimulatory activity of BPE was compared to protein-/lipid-depleted BPE-fractions. In co-cultures of BPE-pulsed BMDCs and Bet v 1-specific hybridoma T cells, the influence of the TLR4-dependent DC activation on T cell activation was analyzed. In vivo immunization of IL-4 reporter mice was conducted to study BPE-induced Th2 polarization upon PMB pre-treatment. Murine and human DC activation induced by either BPE or nLPS was inhibited by the TLR4 antagonist or by PMB, and abrogated in TLR4-deficient BMDCs compared to wild-type BMDCs. The lipid-free but not the protein-free fraction showed a reduced capacity to activate the TLR4 signaling and murine DCs. In human DCs, nLPS only partially reproduced the BPE-induced activation intensity. BPE-primed BMDCs efficiently stimulated T cell activation, which was repressed by the TLR4 antagonist or PMB, and the addition of nLPS to Bet v 1 did not reproduce the effect of BPE. In vivo, immunization with BPE induced a significant Th2 polarization, whereas administration of BPE pre-incubated with PMB showed a decreased tendency. These findings suggest that TLR4 is a major pathway by which BPE triggers DC activation that is involved in the initiation of adaptive immune responses. Further characterization of these BP-derived TLR4 adjuvants could provide new candidates for therapeutic strategies targeting specific mechanisms in BP-induced allergic inflammation.

The Dioscorea Genus (Yam)-An Appraisal of Nutritional and Therapeutic Potentials

The quest for a food secure and safe world has led to continuous effort toward improvements of global food and health systems. While the developed countries seem to have these systems stabilized, some parts of the world still face enormous challenges. Yam (Dioscorea species) is an orphan crop, widely distributed globally; and has contributed enormously to food security especially in sub-Saharan Africa because of its role in providing nutritional benefits and income. Additionally, yam has non-nutritional components called bioactive compounds, which offer numerous health benefits ranging from prevention to treatment of degenerative diseases. Pharmaceutical application of diosgenin and dioscorin, among other compounds isolated from yam, has shown more prospects recently. Despite the benefits embedded in yam, reports on the nutritional and therapeutic potentials of yam have been fragmented and the diversity within the genus has led to much confusion. An overview of the nutritional and health importance of yam will harness the crop to meet its potential towards combating hunger and malnutrition, while improving global health. This review makes a conscious attempt to provide an overview regarding the nutritional, bioactive compositions and therapeutic potentials of yam diversity. Insights on how to increase its utilization for a greater impact are elucidated.

Grown to be Blue-Antioxidant Properties and Health Effects of Colored Vegetables. Part I: Root Vegetables

During the last few decades, the food and beverage industry faced increasing demand for the design of new functional food products free of synthetic compounds and artificial additives. Anthocyanins are widely used as natural colorants in various food products to replenish blue color losses during processing and to add blue color to colorless products, while other compounds such as carotenoids and betalains are considered as good sources of other shades. Root vegetables are well known for their broad palette of colors, and some species, such as black carrot and beet root, are already widely used as sources of natural colorants in the food and drug industry. Ongoing research aims at identifying alternative vegetable sources with diverse functional and structural features imparting beneficial effects onto human health. The current review provides a systematic description of colored root vegetables based on their belowground edible parts, and it highlights species and/or cultivars that present atypical colors, especially those containing pigment compounds responsible for hues of blue color. Finally, the main health effects and antioxidant properties associated with the presence of coloring compounds are presented, as well as the effects that processing treatments may have on chemical composition and coloring compounds in particular.

Research and Development of Proteins and Peptides with Therapeutic Potential from Yam Tubers

We discuss the diverse biological activities, therapeutic potential, and clinical applications of peptides and proteins isolated from various yams species including Dioscorea opposita Thunb (Chinese yam), D alata, D japonica (Japanese yam), D pseudojaponica, D batatas (Korea yam), and D cayenensis. Yam peptides and proteins have many pharmacological activities including immunomodulatory, antioxidant, estrogen-stimulating, osteogenic, angiotensin I-converting enzyme inhibiting, carbonic anhydrase and trypsin inhibiting, chitinase, anti-insect, anti-dust mite, lectin, and anti-proliferative activities. Yam peptides and proteins have therapeutic potential for treating cardiovascular diseases, inflammatory diseases, cancers, aging disorders, menopause, and osteoporosis.

Alkali treated antioxidative crude polysaccharide from Russula alatoreticula potentiates murine macrophages by tunning TLR/NF-κB pathway

In our previous research, Russula alatoreticula was demonstrated as a novel species, ethnic myco-food and reservoir of hot water extractable polysaccharides. However, residue after the hydrothermal process still offer plenty of medicinal carbohydrates that could easily be extracted by using alkali solvent. Thus, the present work was attempted to prepare crude polysaccharide using remainder of the conventional method and subsequently a β-glucan enriched fraction, RualaCap, was isolated. The bio-polymers displayed pronounced therapeutic efficacy as evident by radical scavenging, chelating ability, reducing power and total antioxidant capacity. In addition, strong immune-enhancing potential was also observed indicated by augmentation in macrophage viability, phagocytic uptake, nitric oxide (NO) production and reactive oxygen species (ROS) synthesis. Alongside, the polysaccharides effectively triggered transcriptional activation of Toll like receptor (TLR)-2, TLR-4, nuclear factor kappa B (NF-κB), cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, Iκ-Bα, interferon (IFN)-γ and interleukin (IL)-10 genes explaining mode of action. Taken together, our results signify possibility of RualaCap as a potent nutraceutical agent and enhance importance of R. alatoreticula especially in the field of innate immune stimulation.

Pilloin, A Flavonoid Isolated from Aquilaria sinensis, Exhibits Anti-Inflammatory Activity In Vitro and In Vivo

Flavonoids, widely present in medicinal plants and fruits, are known to exhibit multiple pharmacological activities. In this study, we isolated a flavonoid compound, pilloin, from Aquilaria sinensis and investigated its anti-inflammatory activity in bacterial lipopolysaccharide-induced RAW 264.7 macrophages and septic mice. Pilloin inhibited NF-κB activation and reduced the phosphorylation of IκB in LPS-stimulated macrophages. Moreover, pilloin significantly suppressed the production of pro-inflammatory molecules, such as TNF-α, IL-6, COX-2 and iNOS, in LPS-treated RAW 264.7 macrophages. Additionally, pilloin suppressed LPS-induced morphological alterations, phagocytic activity and ROS elevation in RAW 264.7 macrophages. The mitogen-activated protein kinase-mediated signalling pathways (including JNK, ERK, p38) were also inhibited by pilloin. Furthermore, pilloin reduced serum levels of TNF-α (from 123.3 ± 7 to 46.6 ± 5.4 ng/mL) and IL-6 levels (from 1.4 ± 0.1 to 0.7 ± 0.1 ng/mL) in multiple organs of LPS-induced septic mice (liver: from 71.8 ± 3.2 to 36.7 ± 4.3; lung: from 118.6 ± 10.6 to 75.8 ± 11.9; spleen: from 185.9 ± 23.4 to 109.6 ± 18.4; kidney: from 160.3 ± 11.8 to 75 ± 10.8 pg/mL). In summary, our results demonstrate the anti-inflammatory potential of pilloin and reveal its underlying molecular mechanism of action.

Acylphloroglucinol Derivatives from Garcinia multiflora with Anti-Inflammatory Effect in LPS-Induced RAW264.7 Macrophages

Two new acylphloroglucinol derivatives, 13,14-didehydroxygarcicowin C (1) and 13,14-didehydroxyisoxanthochymol (2), have been isolated from the stems of Garcinia multiflora, together with seven known compounds (3⁻9). The structures of new compounds 1 and 2 were elucidated by MS and extensive 1D/2D NMR spectroscopic analyses. Among the isolates, 13,14-didehydroxy-isoxanthochymol (2) and sampsonione B (3) exhibited inhibition against lipopolysaccharide (LPS)-induced NF-κB activation in macrophages at 30 μM with relative luciferase activity values (inhibitory %) of 0.75 ± 0.03 (24 ± 4%) and 0.12 ± 0.03 (88 ± 4%), respectively. Additionally, sampsonione B (3) reduced LPS-induced nitric oxide (NO) production in murine RAW264.7 macrophages and did not induce cytotoxicity against RAW 264.7 cells after 24 h treatment. Compound 3 is worth further investigation and may be expectantly developed as an anti-inflammatory drug candidate.

Water Soluble Antioxidative Crude Polysaccharide From Russula senecis Elicits TLR Modulated NF-κB Signaling Pathway and Pro-inflammatory Response in Murine Macrophages

Russula senecis has recently been reported as a new addition to macrofungal flora of West Bengal. Besides, it also emerged as a seasonal health promoting nutrient to local ethnic people and enlisted for the first time as tribal food in our previous publication. In this context, the present work was designed to establish such usefulness scientifically and to meet the aim, crude polysaccharide, Rusenan, was prepared using conventional heated water reflux. Initially, the polymers were characterized to determine chemical composition and for that spectrophotometry along with Fourier-transform infrared spectroscopy (FT-IR), high-performance thin-layer chromatography (HPTLC), and gas chromatography-mass spectrometry (GC-MS) were performed. Analysis indicated that Rusenan was consisted mainly of carbohydrate conjugated with trace amount of protein. Furthermore, glucose was detected as the major monosaccharide (mainly in β-type glycosidic linkage) while other monomers were presented in the order of galactose > mannose > xylose > rhamnose. Conversely, antioxidant potential was determined following eight in vitro systems where the fraction evidenced strong superoxide, hydroxyl, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activity, high affinity to Fe²⁺ as well as instant ability to donate electron with EC₅₀ values ranging from 80 to 3885 μg/ml concentration. In addition, effect on murine macrophages was also investigated where the polysaccharide treatment increased cell proliferation, phagocytic activity, filopodia or lamellipodia formation, nitric oxide (NO) production and reactive oxygen species (ROS) synthesis. Thereafter, through reverse transcriptase polymerase chain reaction (RT-PCR) analysis, significant increase in the expression of Toll like receptor (TLR)-4, TLR-2 and nuclear factor kappa B (NF-κB) was observed; as a result alleviated level of cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, IκB-α, and interferon (IFN)-γ were also noticed explaining definite immune-stimulatory activity of the fraction. Thus, overall finding suggests that R. senecis can be considered as a functional food and may be used in preparation of dietary supplement to enhance general health.

Development of Yam Dioscorin-Loaded Nanoparticles for Paracellular Transport Across Human Intestinal Caco-2 Cell Monolayers

Dioscorins, the major storage proteins of yam tubers, exert immunomodulatory activities. To improve oral bioavailability of dioscorins in the intestine, recombinant dioscorin (rDioscorin) was coated with N,N,N-trimethyl chitosan (TMC) and tripolyphosphate (TPP), resulting in the formation of TMC-rDio-TPP nanoparticles (NPs). The loading capacity and entrapment efficiency of rDioscorin in the NPs were 26 ± 0.7% and 61 ± 1.4%, respectively. The NPs demonstrated a substantial release profile in the pH environment of the jejunum. The rDioscorin released from the NPs stimulated proliferation and phagocytosis of the macrophage RAW264.7 and activated the gene expression of IL-1β and IL-6. Incubation of the NPs in the Caco-2 cell monolayer led to a 5.2-fold increase of P_app compared with rDioscorin alone, suggesting that rDioscorin, with the assistance of TMC, can be promptly transported across the intestinal epithelia. These results demonstrate that the TMC-rDio-TPP NPs can be utilized for elucidating the immunopharmacological effects of dioscorins through oral delivery.

2-(2-Phenylethyl)-4H-chromen-4-one Derivatives from the Resinous Wood of Aquilaria sinensis with Anti-Inflammatory Effects in LPS-Induced Macrophages

The resinous wood of Aquilaria sinensis, known as agarwood (Chen Xiang in Chinese), is traditionally used for the treatment of abdominal pain, vomiting, circulatory disorders, and dyspnea. Four new 2-(2-phenylethyl)-4H-chromen-4-one derivatives, namely 7-methoxy-2-[2-(4′-hydroxy-phenyl)ethyl]chromone (1), 7-hydroxy-2-[2-(4′-methoxyphenyl)ethyl]chromone (2), 5,6-dihydroxy- 2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]chromone (3), and 6-hydroxy-5-methoxy-2-(2-phenyl-ethyl)chromone (4), have been isolated from the resinous wood of A. sinensis, together with nine known compounds. The structures of these compounds were determined through spectroscopic and MS analyses. Among the isolated compounds, neopetasan, 7-methoxy-2-(2-phenylethyl)-chromone, 6,7-dimethoxy-2-(2-phenylethyl)chromone, and 6,7-dimethoxy-2-[2-(4′-methoxy-phenyl)ethyl]chromone inhibited NF-κB activation in LPS-stimulated RAW 264.7 macrophages with relative luciferase activity values of 0.55 ± 0.09, 0.54 ± 0.03, 0.31 ± 0.05, and 0.38 ± 0.14, respectively, versus that of vehicle control (1.03 ± 0.02). In addition, 5,6-dihydroxy-2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]chromone, 7-methoxy-2-(2-phenylethyl)chromone, 7-dimethoxy-2-(2-phenylethyl)chromone, and 6,7-dimethoxy-2-[2-(4′-methoxyphenyl)ethyl]chromone could suppress LPS-induced NO production in RAW 264.7 cells and did not induce cytotoxicity against RAW 264.7 cells after 24-h treatment.

Characterization of the Dioscorin Gene Family in Dioscorea alata Reveals a Role in Tuber Development and Environmental Response

Dioscorin is one of the major soluble proteins in yam tubers. Unlike other well-known plant storage proteins, such as patatin and sporamin, dioscorin is argued for its function as storage proteins, and the molecular mechanisms underlying its expressional complexity are little understood. In this study, we isolated five dioscorin genes from Dioscorea alata L., comprising three class A (Da-dio1, -3 and -4) and two class B (Da-dio2 and -5) isoforms. Expressions of all dioscorin genes gradually decreased in mother tubers during yam sprouting and regrowth. On the other hand, all dioscorin genes accumulated transcripts progressively with tuber development in new tubers, with Da-dio5 being the most prominent isoform. In yam leaves, the expressions of Da-dio5 were up-regulated by the treatments of five phytohormones (gibberellic acid, salicylic acid, indole-3-acetic acid, abscisic acid, and ethylene), and three abiotic stresses (high-temperature, low-temperature and drought). To further elucidate the regulatory mechanisms of Da-dio5 expressions, transgenic Arabidopsis plants harboring the Da-dio5 promoter-β-glucuronidase (GUS) fusion were generated. GUS staining showed that expressions of the Da-dio5 promoter were detected mainly in the shoot apical meristem (SAM) and hypocotyls, and enhanced by the treatments of the five hormones, and the three abiotic stresses mentioned above. These results suggest diverse roles of Da-dio5 in yam sprouting, regrowth, and tuberization, as well as in response to enviromental cues.

Phytochemicals Approach for Developing Cancer Immunotherapeutics

Phytochemicals or their derived compounds are being increasingly recognized as potentially potent complementary treatments for cancer. Among them, some phytochemicals are being actively evaluated for use as adjuvants in anticancer therapies. For instance, shikonin and hypericin were found to induce immunogenic cell death of specific cancer cells, and this effect was able to further activate the recognition activity of tumor cells by the host immune system. On the other hand, some derivatives of phytochemicals, such as dihydrobenzofuran lignan (Q2-3) have been found to induce the secretion of an endogenous anticancer factor, namely IL-25, from non-malignant cells. These findings suggest that phytochemicals or their derivatives confer a spectrum of different pharmacological activities, which contrasts with the current cytotoxic anticancer drugs commonly used in clinics. In this review, we have collected together pertinent information from recent studies about the biochemical and cellular mechanisms through which specific phytochemicals regulate target immune systems in defined tumor microenvironments. We have further highlighted the potential application of these immunotherapeutic modifiers in cell-based cancer vaccine systems. This knowledge provides useful technological support and know how for future applications of phytochemicals in cancer immunotherapy.

A Novel, Stable, Estradiol-Stimulating, Osteogenic Yam Protein with Potential for the Treatment of Menopausal Syndrome

A novel protein, designated as DOI, isolated from the Chinese yam (Dioscorea opposita Thunb.) could be the first protein drug for the treatment of menopausal syndrome and an alternative to hormone replacement therapy (HRT), which is known to have undesirable side effects. DOI is an acid- and thermo-stable protein with a distinctive N-terminal sequence Gly-Ile-Gly-Lys-Ile-Thr-Thr-Tyr-Trp-Gly-Gln-Tyr-Ser-Asp-Glu-Pro-Ser-Leu-Thr-Glu. DOI was found to stimulate estradiol biosynthesis in rat ovarian granulosa cells; induce estradiol and progesterone secretion in 16- to 18-month-old female Sprague Dawley rats by upregulating expressions of follicle-stimulating hormone receptor and ovarian aromatase; counteract the progression of osteoporosis and augment bone mineral density; and improve cognitive functioning by upregulating protein expressions of brain-derived neurotrophic factor and TrkB receptors in the prefrontal cortex. Furthermore, DOI did not stimulate the proliferation of breast cancer and ovarian cancer cells, which suggest it could be a more efficacious and safer alternative to HRT.

Lignin-rich enzyme lignin (LREL), a cellulase-treated lignin-carbohydrate derived from plants, activates myeloid dendritic cells via Toll-like receptor 4 (TLR4)

Lignin-carbohydrates, one of the major cell wall components, are believed to be the structures that form chemical linkage between lignin and cell wall polysaccharides. Due to the molecular complexity of lignin-containing substances, their isolation and the assignment of their biological activities have so far remained a difficult task. Here, we extracted two lignin-containing carbohydrates, lignin-rich enzyme lignin (LREL) and pure enzyme lignin (PEL), from barley husk and demonstrated that they act as immune stimulators of dendritic cells (DCs), which are particularly important in linking innate and adaptive immunity. Thioacidolysis, acid hydrolysis, and mild alkali hydrolysis of both LREL and PEL revealed that their immunostimulatory activities depended on the lignin structure and/or content, neutral sugar content (especially the characteristic distribution of galactose and mannose), and presence of an ester bond. Furthermore, we showed that the immunostimulatory potency of the lignin-carbohydrate depended on its molecular weight and degree of polymerization. We also demonstrated that the LREL-induced activation of DCs was mediated via TLR4. Thus, LREL-induced increases in the expression levels of several cell surface marker proteins, production of inflammatory cytokines IL-12p40 and TNF-α, and activation and nuclear translocation of transcription factors, as was observed in the WT DCs, were completely abrogated in DCs derived from the TLR4(-/-) mice but not in DCs derived from the TLR2(-/-), TLR7(-/-), and TLR9(-/-) mice. We further demonstrated that LRELs isolated from other plant tissues also activated DCs. These immunostimulatory activities of lignin-carbohydrates, extracted from edible plant tissues, could have potential relevance in anti-infectious immunity and vaccine adjuvants.

Biological activities and applications of dioscorins, the major tuber storage proteins of yam

Yam tubers, a common tuber crop and an important traditional Chinese medicine in Taiwan, have many bioactive substances, including phenolic compounds, mucilage polysaccharides, steroidal saponins and proteins. Among the total soluble proteins, 80% of them are dioscorins. In the past two decades, many studies showed that dioscorins exhibited biological activities both in vitro and in vivo, including the enzymatic, antioxidant, antihypertensive, immunomodulatory, lectin activities and the protecting role on airway epithelial cells against allergens in vitro. Some of these activities are survived after chemical, heating process or enzymatic digestion. Despite of lacking the intact structural information and the detail action mechanisms in the cells, yam dioscorins are potential resources for developing as functional foods and interesting targets for food protein researchers.

Asn-Trp dipeptides improve the oxidative stress and learning dysfunctions ind-galactose-induced BALB/c mice

Asn-Trp (NW) interventions for 4 weeks can attenuate the oxidative stress and learning dysfunctions induced by dailyd-galactose subcutaneous injection for 8 weeks.

Suppression of allergic reactions in ovalbumin-sensitized mice by yam storage proteins dioscorins

To study the biomedical functions of dioscorins isolated from various species of Dioscorea , we investigated their antiallergic potential using an OVA-induced allergy mouse model. All the dioscorins suppressed allergic reactions by decreasing the serum IgE and histamine levels. The serum IFN-γ and IgG2a levels increased in all the dioscorin-treated mice. The spleen cells from the dioscorin-treated mice also exhibited an up-regulation of IFN-γ secretion in response to ConA stimulation. Although dioscorins did not affect the IgG1 levels, the IL-5 levels decreased to basal levels in mice treated with dioscorins of D. alata or D. japonica and in most of the lymphoid cells of the dioscorin-treated mice in response to ConA stimulation. The decrease of IgE and histamine levels was concomitant with an increase in IFN-γ and IgG2a levels and with a decrease in IL-5 levels, suggesting that dioscorins suppressed the OVA-induced allergic reactions, possibly through modulating an imbalanced Th1/Th2 immune response.

Specific Dioscorea Phytoextracts Enhance Potency of TCL-Loaded DC-Based Cancer Vaccines

Dioscorea tuber phytoextracts can confer immunomodulatory activities ex vivo and improve regeneration of bone marrow cells in vivo. In present study, we evaluated specific Dioscorea phytoextracts for use ex vivo as a bone-marrow-derived dendritic cell- (DC-) based vaccine adjuvant for cancer immunotherapy. Fractionated Dioscorea extracts (DsII) were assayed for their effect on maturation and functions of DC ex vivo and antimelanoma activity of DC-based vaccine in vivo. The phytoextract from 50–75% ethanol-precipitated fraction of Dioscorea alata var. purpurea Tainung no. 5 tuber, designated as DsII-TN5, showed a strong augmentation of tumor cell lysate- (TCL-) loaded DC-mediated activation of T-cell proliferation. DsII-TN5 stimulated the expression of CD40, CD80, CD86, and IL-1β in TCL-loaded DCs and downregulated the expression of TGF-β1. DC vaccines prepared by a specific schema (TCL (2 h) + LPS (22 h)) showed the strongest antitumor activity. DsII-TN5 as a DC vaccine adjuvant showed strong antimelanoma activity and reduced myeloid-derived suppressor cell (MDSC) population in tested mice. DsII-TN5 can also activate DCs to enhance Th1- and Th17-related cytokine expressions. Biochemical analysis showed that DsII-TN5 consists mainly of polysaccharides containing a high level (53%) of mannose residues. We suggest that DsII-TN5 may have potential for future application as a potent, cost-effective adjuvant for DC-based cancer vaccines.

Molecular cloning, structural analysis and mass spectrometric identification of native dioscorins of various yam species

BACKGROUND

Dioscorins are the major storage proteins of yam tubers. However, the molecular nature of their heterogeneity in tubers has not been fully elucidated. In this study the authors isolated the dioscorin gene families of Dioscorea japonica and Dioscorea pseudojaponica, performed matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) and elucidated which dioscorin isoforms are the major constituents in tubers.

RESULTS

The dioscorin gene families of D. japonica (Dj-dioA1-Dj-dioA4, Dj-dioB1 and Dj-dioB2) and D. pseudojaponica (Dp-dioA1-Dp-dioA5 and Dp-dioB1) were cloned from cDNA libraries of yam tubers. The dioscorins isolated from Dioscorea alata (Da-dioscorins), D. japonica (Dj-dioscorins) and D. pseudojaponica (Dp-dioscorins) were mainly monomers, with a few dimers. The monomers contained one intramolecular disulfide bond (Cys(28)-Cys(187)) and belonged to Class A dioscorins with two cysteine residues. The dimers consisted of Class B dioscorins with one intermolecular disulfide bond (Cys(40)-Cys(40)). Results of MALDI-TOF-MS revealed that the Da-dioscorins were mainly encoded by Da-dioA2, Da-dioA3 and Da-dioA4. The majority of the Dj-dioscorins were encoded by Dj-dioA1, Dj-dioA2, Dj-dioA3 and Dj-dioB2. The Dp-dioscorins mainly comprised proteins encoded by Dp-dioA1, Dp-dioA3, Dp-dioA4, Dp-dioB1 and Dp-dioB2.

CONCLUSION

Determination of the constituents of dioscorin isoforms in yam tubers provides a basis for future studies of their physiological and biomedical functions.

Synergistic Induction of iNOS by IFN-γ and Glycoprotein Isolated from Dioscorea batatas

Dioscorea species continue to be used in traditional Chinese medicine, and represent a major source of steroid precursors for conventional medicine. In the previous study, We isolated glycoprotein (GDB) from Dioscorea batatas, characterized, and demonstrated immunostimulating activity in C57BL/6 mice. The aim of this study was to investigate the mechanism whereby GDB activates macrophages. Macrophages activation by GDB was investigated by analyzing the effects of GDB on nitric oxide (NO) production, iNOS expression, mitogen activated protein kinase (MAPK) phosphorylation, and transcription factor activation. In the presence of IFN-γ, GDB strongly stimulated macrophages to express iNOS and produce NO. Furthermore, the activation of p38 was synergistically induced by GDB plus IFN-γ , but SB203580 (a p38 inhibitor) inhibited GDB plus IFN-γ-induced p38 activation. This study indicates that GDB is an important activator of macrophages. Furthermore, due to the critical role that macrophage activation plays in innate immune response, the activation effects of GDB on macrophages suggest that GDB may be a useful immunopotentiating agent.

Recombinant dioscorins of the yam storage protein expressed in Escherichia coli exhibit antioxidant and immunomodulatory activities

Dioscorins, the major storage proteins in yam tubers, exhibit biochemical and immunomodulatroy activities. To investigate the potential application of dioscorins in biomedical research, we expressed the dioscorin genes Dj-dioA3 and Dp-dioA2 from Dioscorea japonica and Dioscorea pseudojaponica, respectively, in E. coli and routinely obtained approximately 15 mg proteins per liter Escherichia coli culture (mg/L) to 30 mg/L of rDj-dioscorinA3 and 4 to 8 mg/L of rDp-dioscorinA2. Western blot analyses revealed that both recombinant dioscorins contained epitopes with similar antigenicities to those of the native dioscorins. Results from dithiothreitol (DTT) treatment followed by monobromobimane (mBBr) staining showed that both recombinant dioscorins, like the native dioscorins, contain an intramolecular disulfide bond between Cys(28) and Cys(187) residues. Circular dichroism spectroscopy findings indicated that the secondary structural contents of the recombinant dioscorins showed high similarity to those of their corresponding native dioscorins. Both recombinant dioscorins, like the native dioscorins, exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and Toll-like receptor 4 signaling activities, and stimulated the phagocytosis of E. coli by macrophage. Overall, our results indicated that substantial amounts of recombinant dioscorins can be purified easily from E. coli and that these recombinant dioscorins are appropriate for application in future investigations of the biomedical functions of dioscorins.

Developing Phytocompounds from Medicinal Plants as Immunomodulators

Imbalance or malfunction of the immune systems is associated with a range of chronic diseases including autoimmune diseases, allergies, cancers and others. Various innate and adaptive immune cells that are integrated in this complex networking system may represent promising targets for developing immunotherapeutics for treating specific immune diseases. A spectrum of phytochemicals have been isolated, characterized and modified for development and use as prevention or treatment of human diseases. Many cytotoxic drugs and antibiotics have been developed from phytocompounds, but the application of traditional or new medicinal plants for use as immunomodulators in treating immune diseases is still relatively limited. In this review, a selected group of medicinal herbs, their derived crude or fractionated phytoextracts and the specific phytochemicals/phytocompounds isolated from them, as well as categorized phytocompound groups with specific chemical structures are discussed in terms of their immunomodulatory bioactivities. We also assess their potential for future development as immunomodulatory or inflammation-regulatory therapeutics or agents. New experimental approaches for evaluating the immunomodulatory activities of candidate phytomedicines are also discussed.

Proteomics characterization of cytoplasmic and lipid-associated membrane proteins of human pathogen Mycoplasma fermentans M64

Mycoplasma fermentans is a potent human pathogen which has been implicated in several diseases. Notably, its lipid-associated membrane proteins (LAMPs) play a role in immunomodulation and development of infection-associated inflammatory diseases. However, the systematic protein identification of pathogenic M. fermentans has not been reported. From our recent sequencing results of M. fermentans M64 isolated from human respiratory tract, its genome is around 1.1 Mb and encodes 1050 predicted protein-coding genes. In the present study, soluble proteome of M. fermentans was resolved and analyzed using two-dimensional gel electrophoresis. In addition, Triton X-114 extraction was carried out to enrich amphiphilic proteins including putative lipoproteins and membrane proteins. Subsequent mass spectrometric analyses of these proteins had identified a total of 181 M. fermentans ORFs. Further bioinformatics analysis of these ORFs encoding proteins with known or so far unknown orthologues among bacteria revealed that a total of 131 proteins are homologous to known proteins, 11 proteins are conserved hypothetical proteins, and the remaining 39 proteins are likely M. fermentans-specific proteins. Moreover, Triton X-114-enriched fraction was shown to activate NF-kB activity of raw264.7 macrophage and a total of 21 lipoproteins with predicted signal peptide were identified therefrom. Together, our work provides the first proteome reference map of M. fermentans as well as several putative virulence-associated proteins as diagnostic markers or vaccine candidates for further functional study of this human pathogen.

Crystallization and preliminary X-ray crystallographic analysis of dioscorin from Dioscorea japonica

Dioscorin, the major tuber storage protein in yam, has been reported to possess carbonic anhydrase, trypsin inhibitor, angiotensin-converting enzyme (ACE) inhibitor, free-radical scavenger, dehydroascorbate reductase and monodehydroascorbate reductase activities. Recent research has also found that dioscorin can enhance immune modulation via the toll-like receptor 4 (TLR-4) signal transduction pathway in RAW 264.7 cells, murine bone-marrow cells and human monocytes ex vivo. Resolving the structure of dioscorin would help in better understanding its activities and would provide clues to understanding the mechanism of its multiple functions. The full-length protein (residues 1-246) with an additional His(6) tag at the N-terminus was expressed in Escherichia coli Rosetta (DE3) cells. After His-tag cleavage and purification, the protein was crystallized by the sitting-drop vapour-diffusion method at 278 K. An X-ray diffraction data set was collected to a resolution of 2.11 Å using a synchrotron X-ray source. The crystal belonged to space group C222(1), with unit-cell parameters a = 83.5, b = 156.8, c = 83.6 Å, and was estimated to contain two protein molecules per asymmetric unit.

Characterization and immunopotentiating effects of the glycoprotein isolated from dioscorea batatas

We demonstrate that glycoprotein isolated from Dioscorea batatas (GDB) has immunostimulatory effects including macrophage activation. Analysis of infiltration of inflammatory cells into peritoneal cavity showed GDB treatment significantly increased the recruitment of macrophages, lymphocytes, neutrophils, and monocytes into the peritoneal cavity. Treatment of spleen cells isolated from C57BL/6 mice with GDB significantly increased the proliferation of B cells and T cells induced by LPS and ConA, respectively. Treatment with GDB significantly increased the cytolytic capacity of NK cells and macrophages against YAC-1 and B16 cells, respectively. In order to further confirm and investigate the mechanism of GDB on macrophage activation, we analyzed the effects of GDB on the cytokine expression including iNOS, IL-1β, and TNF-α in mouse macrophage cell line, RAW 264.7 cells. RT-PCR and ELISA showed that GDB increased the expression of IL-1β, and TNF-α, whereas iNOS was not induced by GDB. Collectively, this series of experiments indicates that GDB stimulates immune system including macrophage activation.

ATF3 plays a key role in Kdo2-lipid A-induced TLR4-dependent gene expression via NF-κB activation

BACKGROUND

Activating transcription factor 3 (ATF3) is a negative regulator of proinflammatory cytokine expression in macrophages, and ATF3 deficient mice are more susceptible to endotoxic shock. This study addresses the role of ATF3 in the Kdo(2)-Lipid A-induced Toll-like receptor 4 (TLR4) signaling pathway in mouse embryonic fibroblasts (MEF). Kdo(2)-Lipid A upregulates ATF3 expression in wild type MEF cells and induces both nuclear factor kappa B (NF-κB) and c-Jun N-terminal kinase (JNK) activation via the TLR4 signaling pathway, while neither of these pathways is activated in ATF3-/- MEF cells. Interestingly, in contrast to Kdo(2)-Lipid A, the activation of both NF-κB and JNK by TNF-α was normal in ATF3-/- MEF cells.

METHODOLOGY/PRINCIPAL FINDINGS

We found that several genes were dramatically upregulated in ATF3+/+ MEF cells in response to Kdo(2)-Lipid A treatment, while little difference was observed in the ATF3-/- MEF cells. However, we also found that the signal intensities of IκBζ in ATF3-/- MEF cells were substantially higher than those in wild type MEF cells upon microarray analyses, and upregulated IκBζ expression was detected in the cytosol fraction.

CONCLUSIONS/SIGNIFICANCE

Our findings indicate that ATF3 deficiency affects Kdo(2)-Lipid A-induced TLR4 signaling pathways in MEF cells, that it may upregulate IκBζ expression and that the high levels of IκBζ expression in ATF3-/- cells disrupts Kdo(2)-Lipid A-mediated signaling pathways.

Fisetin inhibits lipopolysaccharide-induced macrophage activation and dendritic cell maturation

Macrophages and dendritic cells are required for initiating innate immunity and adaptive immunity. Aberrant activation of macrophages and dendritic cells can cause detrimental immune responses; thus, agents effectively modulating their functions are of great clinical value. We herein investigated whether fisetin, a flavonoid prevalently present in fruits and vegetables, could inhibit macrophage activation and dendritic cell maturation. Fisetin suppressed LPS-induced NF-κB activation, expression of pro-inflammatory proteins (TNF-α and iNOS), MMP-9 activity, and phagocytic activity in macrophages. Furthermore, upon LPS-induced dendritic cell maturation, fisetin at nontoxic concentrations suppressed the expression of costimulatory molecules (CD80 and CD86), the production of cytokines (IL-12, IL-6, and TNF-α), and the endocytic activity of dendritic cells. Fisetin treatment significantly attenuated migration of dendritic cells into spleens and dendritic cell-mediated T cell activation in LPS-treated mice. Collectively, our data reveal that fisetin inhibits macrophage activation and impairs functional maturation of dendritic cells.

The assessment of efficacy of Diascorea alata for menopausal symptom treatment in Taiwanese women

OBJECTIVE

The aim of this study was to assess the efficacy and safety of Diascorea alata for treatment of menopausal symptoms.

MATERIALS AND METHODS

Two-center, randomized, double-blind, placebo-controlled clinical investigation on 50 menopausal women randomly assigned to two groups, treated for 12 months with either placebo or two sachets daily of Diascorea extracts containing 12 mg/sachet. Primary outcome measures were changes in the Greene Climacteric Scale caused by Diascorea compared with placebo; secondary outcomes were changes in plasma hormone profiles. One-way ANCOVA test was performed to investigate the significance.

RESULTS

At 6 months and at the end of treatment, those women who received Diascorea showed general improvement in almost all the clinical symptoms investigated. A significant reduction was noted in the total Greene scores in the Diascorea group assessed at the end of 12 months' treatment (p < 0.01). This phenomenon was more significant for the psychological parameters of anxiety than for other parameters. Apparent improvements were noted in the parameters 'feeling tense or nervous' (p = 0.007), 'insomnia' (p = 0.004), 'excitable' (p = 0.047) and 'musculoskeletal pain' (p = 0.019) among those receiving Diascorea. Diascorea consumption also resulted in positive effects on blood hormone profiles.

CONCLUSIONS

Compared with placebo, Diascorea alata improves symptoms, particularly the psychological parameters in menopausal women. Safety monitoring indicated that standardized extracts of Diascorea alata were safe during daily administration over a period of 12 months.

Upregulation of TLR2/4 expression in mononuclear cells in postoperative systemic inflammatory response syndrome after liver transplantation

BACKGROUND

To explore the relationship between Toll-like rpheral blood mononuclear cells (PBMC) and systemic inflammatory response syndrome (SIRS) in postoperative patients of liver transplantation (LT).

METHODS

Blood samples of 27 patients receiving LT were collected at T1 (after induction of anaesthesia), T2 (25 minutes after the beginning of anhepatic phase), T3 (3 hours after graft reperfusion), and T4 (24 hours after graft reperfusion). The expression of TLR2/4 on PBMC and serum concentration of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-8 were measured. The patients were divided into SIRS group (n = 12) and non-SIRS group (n = 15) for analysis.

RESULTS

Blood loss and transfusion were higher in the SIRS group than in the non-SIRS group. Both the preanhepatic and anhepatic phase were significantly longer in the SIRS group. The TLR2/4 expression on PBMC as well as serum TNF-alpha, IL-1beta, and IL-8 were significantly higher at T3 and T4 than that at T1 and T2 in the SIRS patients. The expression of TLR4 on PBMC is positively correlated to serum TNF-alpha, IL-8. Expression of TLR2/4 on PBMC and serum concentrations of TNF-alpha, IL-1beta, did not differ among the 4-time points in non-SIRS patients.

CONCLUSIONS

Upregulation of TLR2/4 expression on PBMC may contribute to the development of postoperative SIRS during perioperative period of LT.

Yam storage protein dioscorins from Dioscorea alata and Dioscorea japonica exhibit distinct immunomodulatory activities in mice

The aim of this study was to elucidate the effect of the major storage protein dioscorin isolated from two different yam species, Tainong No. 1 (TN1-dioscorins) and Japanese yam (Dj-dioscorins), on the immune activities of mice. Dj-dioscorins, like TN1-dioscorins, could induce expression of the pro-inflammatory cytokines and stimulate phagocytosis of RAW 264.7. Intraperitoneal injection of the TN1-dioscorins into mice stimulated phagocytosis of bone marrow, spleen, and thymic cells. In contrast, the T and B cells in bone marrow, spleen, and thymus isolated from mice injected with Dj-dioscorins had higher proliferative responses to mitogens. Furthermore, Dj-dioscorins enhanced proliferation of CD4(+), CD8(+), and Tim3(+) (Th1) cells in spleen and CD19(+) cells in both spleen and thymus. Supplement of Dj-dioscorins in the lymphoid cells isolated from Dj-dioscorins primed mice induced cell proliferation of both spleen and thymic cells. These findings indicated that TN1-dioscorins have a higher ability to stimulate the phagocytic activity of the lymphoid cells than Dj-dioscorins, whereas Dj-dioscorins possess more abilities than TN1-dioscorins to enhance the proliferation of the lymphoid cells.

Polysaccharides from Dioscorea batatas induce tumor necrosis factor-alpha secretion via Toll-like receptor 4-mediated protein kinase signaling pathways

The bioactive polysaccharides (named ZPF1) from yam ( Dioscorea batatas) were chemically determined, suggesting repeating beta-1,4-mannan as mainly having a feature of acetylation on C2-OH and C3-OH, around 28%. The ZPF1 participated in the stimulation of murine wild-type macrophages predominantly in tumor necrosis factor-alpha (TNFalpha). Toll-like receptor 4 is proved to be one of the cellular receptors in ZPF1-mediated TNFalpha secretion. Reactive oxygen species transmission and PI3-kinase are found necessary for regulating TNFalpha secretion by ZPF1 stimulation. Moreover, we found that extracellular signal-regulated kinase 1/2, Jun N-terminal kinase 1/2, and p38 mitogen-activated protein kinase play important roles in the regulation of TNFalpha secretion in ZPF1-stimulated macrophages.

Aqueous extract of Rhodiola imbricata rhizome stimulates Toll-like receptor 4, granzyme-B and Th1 cytokines in vitro

Rhodiola imbricata is a medicinal plant, native to mountainous regions of Asia, parts of Europe, and the Arctic. Traditionally it is recommended to help combat fatigue and restore energy. It exhibits anti-stress, anti-cancer, and immunostimulatory activities. However, the effect of Rhodiola on immunological responses largely remains unknown. In this study, we have investigated the effect of aqueous extract of R. imbricata rhizome (RAE), on Toll-like receptor-4 (TLR-4) and intracellular granzyme-B expression in mouse splenocytes. Furthermore, TH1/TH2 cytokine profile was analyzed in RAE-treated human peripheral blood mononuclear cells (PBMCs) using multiplex flowcytomix kit. Our findings suggest that RAE induces TLR-4 expression and intracellular granzyme-B in treated splenocytes while RAE stimulated IL-1beta, IL-6, and TNF-alpha in human PBMCs. The present study suggests that RAE stimulates the innate immune pathway and has potent immunostimulatory activity, which can be used in modulating the immune system of immunocompromised individuals.

The nuclear receptor Rev-erbalpha is a liver X receptor (LXR) target gene driving a negative feedback loop on select LXR-induced pathways in human macrophages

A role of the nuclear receptor Rev-erbalpha in the regulation of transcription pathways involving other nuclear receptors is emerging. Indeed, Rev-erbalpha is a negative regulator of transcription by binding to overlapping response elements shared with various nuclear receptors, including the peroxisome proliferator-activated receptors and the retinoid-related orphan receptor alpha (RORalpha). Here, we show that Rev-erbalpha is expressed in primary human macrophages and that its expression is induced by synthetic ligands for the liver X receptors (LXRs), which control cholesterol homeostasis, inflammation, and the immune response in macrophages. LXRalpha binds to a specific response element in the human Rev-erbalpha promoter, thus inducing Rev-erbalpha transcriptional expression. Interestingly, Rev-erbalpha does not influence basal or LXR-regulated cholesterol homeostasis. However, Rev-erbalpha overexpression represses the induction of toll-like receptor (TLR)-4 by LXR agonists, whereas Rev-erbalpha silencing by short interfering RNA results in enhanced TLR-4 expression upon LXR activation. Electrophoretic mobility shift, chromatin immunoprecipitation, and transient transfection experiments demonstrate that Rev-erbalpha represses human TLR-4 promoter activity by binding as a monomer to a RevRE site overlapping with the LXR response element site in the TLR-4 promoter. These data identify Rev-erbalpha as a new LXR target gene, inhibiting LXR-induction of TLR-4 in a negative transcriptional feedback loop, but not cholesterol homeostasis gene expression.