The natural product phyllanthusmin C enhances IFN-γ production by human NK cells through upregulation of TLR-mediated NF-κB signaling

Arabinogalactan G1-4A isolated from Tinospora cordifolia induces PKC/mTOR mediated direct activation of natural killer cells and through dendritic cell cross-talk

BACKGROUND

Tinospora cordifolia polysaccharide G1-4A activates antigen-presenting cells, but its effect on natural killer (NK) cells is not known. The objective of this study is to assess the effect of G1-4A on NK cells; direct effects as well as through dendritic cell (DC) cross-talk.

METHODS

NK cell phenotype and function were assessed in spleen cells treated in vitro with G1-4A or isolated from mice administered with G1-4A. Following treatment with G1-4A in vitro or in cells isolated from G1-4A treated mice (in vivo), activated NK cell phenotype was characterized as CD3^-NKp46⁺CD69⁺ cells by flow cytometry; NK cell function was evaluated by IFN-γ secretion (ELISA) and cytotoxicity assay (calcein release by target cells in effector: target cells co-culture assay).

RESULTS

Both in vitro as well as in vivoG1-4A treatment increased phenotypic and functional activation of NK cells. So, we wanted to determine if this was through NK-DC crosstalk or direct activation of NK cells. There was increased NK cell activation following co-culture with bone marrow derived DC matured withG1-4A in vitro or splenic DC isolated from G1-4A administered mice indicating crosstalk. G1-4A also increased activation of NK cells in (a) CD11c depleted splenic cells that was contact dependent and (b) purified NKp46⁺ cells that was abrogated by PKC/mTOR inhibitors indicating direct effects on NK cells.

CONCLUSION

In summary, treatment with G1-4A results in phenotypic and functional activation of NK cells directly as well as through NK-DC cross talk and has the potential to be used as an immunotherapeutic agent.

B7H6 Serves as a Negative Prognostic Marker and an Immune Modulator in Human Pancreatic Cancer

Pancreatic cancer (PC), the third leading cause of cancer-related death in the U.S., is frequently found too late to be cured by traditional chemotherapy. Expression of B7 homolog 6 (B7H6), a member of the B7 family of immunoreceptors, has been found in PC and several other cancers. B7H6 is a ligand for cytotoxicity triggering receptor 3 (NKp30), which is expressed on NK cells. Here, we demonstrate that B7H6 can be detected in PC tissues but not normal organs. Its expression in patients associated significantly with tumor differentiation grade and lymphatic metastasis. The soluble form of B7H6 was detected in the PC patients’ sera, and its concentration associated with tumor differentiation grade and tumor, node, metastasis (TNM) stages. Also, higher levels of B7H6 in PC patients’ malignant tissues or serum correlated with shorter overall survival. In vitro, downregulation of B7H6 by CRISPR/Cas9 or siRNA technology had no significant impact on the viability or mobility of PC cells. Instead, knocking out B7H6 sensitized PC cells to NK-mediated cytotoxicity and cytokine production. These results indicate that B7H6 not only serves as a negative prognostic marker but also acts as an immune modulator in PC.

Identification of nafamostat mesylate as a selective stimulator of NK cell IFN-γ production via metabolism-related compound library screening

Natural killer (NK) cells play important roles in controlling virus-infected and malignant cells. The identification of new molecules that can activate NK cells may effectively improve the antiviral and antitumour activities of these cells. In this study, by using a commercially available metabolism-related compound library, we initially screened the capacity of compounds to activate NK cells by determining the ratio of interferon-gamma (IFN-γ)⁺ NK cells by flow cytometry after the incubation of peripheral blood mononuclear cells (PBMCs) with IL-12 or IL-15 for 18 h. Our data showed that eight compounds (nafamostat mesylate (NM), loganin, fluvastatin sodium, atorvastatin calcium, lovastatin, simvastatin, rosuvastatin calcium, and pitavastatin calcium) and three compounds (NM, elesclomol, and simvastatin) increased the proportions of NK cells and CD3⁺ T cells that expressed IFN-γ among PBMCs cultured with IL-12 and IL-15, respectively. When incubated with enriched NK cells (purity ≥ 80.0%), only NM enhanced NK cell IFN-γ production in the presence of IL-12 or IL-15. When incubated with purified NK cells (purity ≥ 99.0%), NM promoted NK cell IFN-γ secretion in the presence or absence of IL-18. However, NM showed no effect on NK cell cytotoxicity. Collectively, our study identifies NM as a selective stimulator of IFN-γ production by NK cells, providing a new strategy for the prevention and treatment of infection or cancer in select populations.

Screening for Active Compounds Targeting Human Natural Killer Cell Activation Identifying Daphnetin as an Enhancer for IFN-γ Production and Direct Cytotoxicity

Natural killer (NK) cells are a potent weapon against tumor and viral infection. Finding active compounds with the capacity of enhancing NK cell effector functions will be effective to develop new anti-cancer drugs. In this study, we initially screened 287 commercially available active compounds by co-culturing with peripheral blood mononuclear cells (PBMCs). We found that five compounds, namely, Daphnetin, MK-8617, LW6, JIB-04, and IOX1, increased the IFN-γ⁺ NK cell ratio in the presence of IL-12. Further studies using purified human primary NK cells revealed that Daphnetin directly promoted NK cell IFN-γ production in the presence of IL-12 but not IL-15, while the other four compounds acted on NK cells indirectly. Daphnetin also improved the direct cytotoxicity of NK cells against tumor cells in the presence of IL-12. Through RNA-sequencing, we found that PI3K-Akt-mTOR signaling acted as a central pathway in Daphnetin-mediated NK cell activation in the presence of IL-12. This was further confirmed by the finding that both inhibitors of PI3K-Akt and its main downstream signaling mTOR, LY294002, and rapamycin, respectively, can reverse the increase of IFN-γ production and cytotoxicity in NK cells promoted by Daphnetin. Collectively, we identify a natural product, Daphnetin, with the capacity of promoting human NK cell activation via PI3K-Akt-mTOR signaling in the presence of IL-12. Our current study opens up a new potential application for Daphnetin as a complementary immunomodulator for cancer treatments.

Advances in plant-derived natural products for antitumor immunotherapy

In recent years, immunotherapy has emerged as a novel antitumor strategy in addition to traditional surgery, radiotherapy and chemotherapy. It uniquely focuses on immune cells and immunomodulators in the tumor microenvironment and helps eliminate tumors at the root by rebuilding the immune system. Despite remarkable breakthroughs, cancer immunotherapy still faces many challenges: lack of predictable and prognostic biomarkers, adverse side effects, acquired treatment resistance, high costs, etc. Therefore, more efficacious and efficient, safer and cheaper antitumor immunomodulatory drugs have become an urgent requirement. For decades, plant-derived natural products obtained from land and sea have provided the most important source for the development of antitumor drugs. Currently, more attention is being paid to the discovery of potential cancer immunotherapy modulators from plant-derived natural products, such as polysaccharides, phenols, terpenoids, quinones and alkaloids. Some of these agents have outstanding advantages of multitargeting and low side effects and low cost compared to conventional immunotherapeutic agents. We intend to summarize the progress of comprehensive research on these plant-derived natural products and their derivatives and discuss their possible mechanisms in regulating the immune system and their efficacy as monotherapies or in combination with regular chemotherapeutic agents.

Development of Broad-Spectrum Antiviral Agents-Inspiration from Immunomodulatory Natural Products

Developing broad-spectrum antiviral drugs remains an important issue as viral infections continue to threaten public health. Host-directed therapy is a method that focuses on potential targets in host cells or the body, instead of viral proteins. Its antiviral effects are achieved by disturbing the life cycles of pathogens or modulating immunity. In this review, we focus on the development of broad-spectrum antiviral drugs that enhance the immune response. Some natural products present antiviral effects mediated by enhancing immunity, and their structures and mechanisms are summarized here. Natural products with immunomodulatory effects are also discussed, although their antiviral effects remain unknown. Given the power of immunity and the feasibility of host-directed therapy, we argue that both of these categories of natural products provide clues that may be beneficial for the discovery of broad-spectrum antiviral drugs.

Dihydromyricetin ameliorates liver fibrosis via inhibition of hepatic stellate cells by inducing autophagy and natural killer cell-mediated killing effect

Background

This study investigated the mechanisms underlying the preventive effect of dihydromyricetin (DHM) against liver fibrosis involving hepatic stellate cells (HSCs) and hepatic natural killer (NK) cells.

Methods

A carbon tetrachloride (CCl₄)-induced liver fibrosis model was established in C57BL/6 mice to study the antifibrotic effect of DHM based on serum biochemical parameters, histological and immunofluorescence stainings, and the expression of several fibrosis-related markers. Based on the immunoregulatory role of DHM, the effect of DHM on NK cell activation ex vivo was evaluated by flow cytometry. Then, we investigated whether DHM-induced autophagy was involved in HSCs inactivation using enzyme-linked immunosorbent assays, transmission electron microscopy, and western blot analysis. Thereafter, the role of DHM in NK cell-mediated killing was studied by in vitro coculture of NK cells and HSCs, with subsequent analysis by flow cytometry. Finally, the mechanism by which DHM regulates NK cells was studied by western blot analysis.

Results

DHM ameliorated liver fibrosis in C57BL/6 mice, as characterized by decreased serum alanine transaminase and aspartate transaminase levels, decreased expressions of collagen I alpha 1 (CoL-1α1), collagen I alpha 2 (CoL-1α2), tissue inhibitor of metalloproteinases 1 (TIMP-1), α-smooth muscle actin (α-SMA) and desmin, as well as increased expression of matrix metalloproteinase 1 (MMP1). Interestingly, HSCs activation was significantly inhibited by DHM in vivo and in vitro. As expected, DHM also upregulated autophagy-related indicators in liver from CCl₄-treated mice. DHM also prevented TGF-β1-induced activation of HSCs in vitro by initiating autophagic flux. In contrast, the autophagy inhibitor 3-methyladenine markedly abolished the antifibrotic effect of DHM. Surprisingly, the frequency of activated intrahepatic NK cells was significantly elevated by DHM ex vivo. Furthermore, DHM enhanced NK cell-mediated killing of HSCs by increasing IFN-γ expression, which was abolished by an anti-IFN-γ neutralizing antibody. Mechanistically, DHM-induced IFN-γ expression was through AhR-NF-κB/STAT3 pathway in NK cells.

Conclusion

These results demonstrated that DHM can ameliorate the progression of liver fibrosis and inhibition of HSCs activation by inducing autophagy and enhancing NK cell-mediated killing through the AhR-NF-κB/STAT3-IFN-γ signaling pathway, providing new insights into the preventive role of DHM in liver fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00589-6.

Preliminary chemical characterization of ethanolic extracts from Colombian plants with promising anti - Trypanosoma cruzi activity

Chagas disease is caused by Trypanosoma cruzi, and it is an important cause of morbidity and mortality in Latin America. There are no vaccines, and the chemotherapy available to treat this infection has serious side effects. In a search for alternative treatments, we determined the in vitro susceptibility of epimastigote and trypomastigote forms of T. cruzi and the cytotoxic effects on peripheral blood mononuclear cells (PBMCs) of ethanolic extracts obtained from six different plant species. The ethanolic extracts of Ageratina vacciniaefolia, Clethra fimbriata and Siparuna sessiliflora showed antiprotozoal activity against epimastigotes and low cytotoxicity in mammalian cells. However, only the ethanolic extract of C. fimbriata showed activity against T. cruzi trypomastigotes, and it had low cytotoxicity in PBMCs. An analysis on the phytochemical composition of C. fimbriata extract showed that its metabolites were primarily represented by two families of compounds: flavonoids and terpenoids. Lastly, we analyzed whether the A. vacciniaefolia, C. fimbriata, or S. sessiliflora ethanolic extracts induced IFN-γ or TNF-α production. Significantly, ethanolic extracts of C. fimbriata induced TNF-α production and S. sessiliflora induced both cytokines. In addition, C. fimbriata and S. sessiliflora induced the simultaneous secretion of IFN-γ and TNF-α in CD8⁺ T cells. The antiprotozoal and immunomodulatory activity of C. fimbriata may be related to the presence of flavonoid and triterpene compounds in the extract. Thus, these findings suggest that C. fimbriata may represent a valuable source of new bioactive compounds for the therapeutic treatment of Chagas disease that combines trypanocidal activity with the capacity to boost the immune response.

Transition Metal-Mediated Annulation Approaches for Synthesis of Arylnaphthalene Lignan Lactones

Arylnaphthalene lignan lactones belong to a class of natural lignans, and more than 60 analogs have been isolated. Their pharmacological activities as well as unique structural features have attracted considerable attention from medicinal and synthetic chemists. Since the first synthesis in 1895, many synthetic methodologies with ionic or pericyclic reaction mechanisms have been reported. Transition metal catalysts sometimes provide exceptional synthetic versatility for the syntheses of natural compounds. Recently, transition metal-mediated methodologies were investigated for the construction of basic scaffolds of arylnaphthalene lignan lactones. Five kinds of transition metal catalysts containing gold, manganese, nickel, palladium, and silver have been explored. Most of the metal catalysts successfully created arylnaphthalene lactones by intermolecular or intramolecular annulative cyclization. In this review, all reports of transition metal-mediated annulative construction of arylnaphthalene lignan lactones were compiled, and synthetic approaches, mechanistic aspects, and successful applications were discussed.

Immune system activation by natural products and complex fractions: a network pharmacology approach in cancer treatment

Natural products and traditional herbal medicine are an important source of alternative bioactive compounds but very few plant-based preparations have been scientifically evaluated and validated for their potential as medical treatments. However, a promising field in the current therapies based on plant-derived compounds is the study of their immunomodulation properties and their capacity to activate the immune system to fight against multifactorial diseases like cancer. In this review we discuss how network pharmacology could help to characterize and validate natural single molecules or more complex preparations as promising cancer therapies based on their multitarget capacities.

TLR1/2 orchestrate human plasmacytoid predendritic cell response to gram+ bacteria

Gram+ infections are worldwide life-threatening diseases in which the pathological role of type I interferon (IFN) has been highlighted. Plasmacytoid predendritic cells (pDCs) produce high amounts of type I IFN following viral sensing. Despite studies suggesting that pDCs respond to bacteria, the mechanisms underlying bacterial sensing in pDCs are unknown. We show here that human primary pDCs express toll-like receptor 1 (TLR1) and 2 (TLR2) and respond to bacterial lipoproteins. We demonstrated that pDCs differentially respond to gram+ bacteria through the TLR1/2 pathway. Notably, up-regulation of costimulatory molecules and pro-inflammatory cytokines was TLR1 dependent, whereas type I IFN secretion was TLR2 dependent. Mechanistically, we demonstrated that these differences relied on diverse signaling pathways activated by TLR1/2. MAPK and NF-κB pathways were engaged by TLR1, whereas the Phosphoinositide 3-kinase (PI3K) pathway was activated by TLR2. This dichotomy was reflected in a different role of TLR2 and TLR1 in pDC priming of naïve cluster of differentiation 4+ (CD4+) T cells, and T helper (Th) cell differentiation. This work provides the rationale to explore and target pDCs in bacterial infection.

Soluble receptor for advanced glycation end-products enhanced the production of IFN-γ through the NF-κB pathway in macrophages recruited by ischemia/reperfusion

The current study investigated the role of sRAGE in the production of IFN‑γ in macrophages with I/R treatment. The number of macrophages in myocardial tissues treated with I/R with or without sRAGE was determined via immunohistochemical staining. Proliferative activity of macrophages was analyzed by a 5‑BrdU incorporation assay. Differentiation of macrophages was detected via immunofluorescence staining of iNOS (M1 macrophage marker). IFN‑γ production, due to sRAGE stimulation, in Raw 264.7 macrophages and the NF‑κB signaling pathway were measured using western blotting. A ChIP assay was used to examine the interactions between NF‑κB and the promoter of IFN‑γ. The results showed that the number of macrophages in I/R‑treated myocardial tissues was increased following sRAGE infusion. Proliferation of macrophages was increased significantly in the presence of sRAGE; after I/R treatment, the cells preferred to differentiate into M1 macrophages. IFN‑γ expression in Raw 264.7 macrophages was suppressed by an NF‑κB inhibitor (Bay117082) but enhanced by sRAGE, with or without I/R treatment. Furthermore, sRAGE increased the phosphorylation of IκB, IKK and NF‑κB, as well as the translocation of NF‑κB into the nucleus of Raw 264.7 macrophages, with or without I/R treatment. ChIP results showed that sRAGE promoted NF‑κB binding to the promoter of IFN‑γ in Raw 264.7 macrophages. Therefore, the findings of the present study indicated that sRAGE protected the heart from I/R injuries, which might be mediated by promoting infiltration and the differentiation of macrophages into M1, which would then synthesize and secrete IFN‑γ through activating the NF‑κB signaling pathway.

Potential Anticancer Agents Characterized from Selected Tropical Plants

Higher plants are well known for their value in affording clinically useful anticancer agents, with such compounds acting against cancer cells by a range of mechanisms of action. There remains a strong interest in the discovery and development of plant secondary metabolites as additional cancer chemotherapeutic lead compounds. In the present review, progress on the discovery of plant-derived compounds of the biflavonoid, lignan, sesquiterpene, steroid, and xanthone structural types is presented. Several potential anticancer leads of these types have been characterized from tropical plants collected in three countries as part of our ongoing collaborative multi-institutional project. Preliminary structure-activity relationships and work on in vivo testing and cellular mechanisms of action are also discussed. In addition, the relevant work reported by other groups on the same compound classes is included herein.

Molecular characterization and functional analysis of IL-12p40 from Chinese sea bass (Lateolabrax maculatus) under biotic and abiotic stresses

Interleukins are critical cytokines that are ubiquitously present in both vertebrates and invertebrates and constitute the front line of host innate immunity. Here, we identified and analyzed IL-12p40 from the Chinese sea bass Lateolabrax maculatus (LmIL-12p40). The LmIL-12p40 gene is expressed as a 1386-base pair transcript that encodes a polypeptide of 321 amino acids. Transcriptional expression analysis indicated that LmIL-12p40 mRNA was ubiquitously expressed in all tested tissues and had a comparatively high expression level in immune-associated tissues (head-kidney and intestines). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) experiments showed that, after Vibro harveyi and Streptococus agalactiae infection, LmIL-12p40 mRNA expression was significantly up-regulated in the spleen, liver and head-kidney. To further clarify the immune function of LmIL-12p40 after bacterial challenge, the recombinant LmIL-12p40 protein was acquired using a prokaryotic expression method. Furthermore, the LmIL-12p40 dimer (LmIL-12p80) could be produced via protein-protein interactions by incubating p40 monomer expressed from the pET28a vector (pET28a-LmIL-12p40) with p40 monomer expressed from the pGEX4T-1 vector (pGEX4T-1-LmIL-12p40). The antimicrobial activity of the purified LmIL-12p40 and LmIL-12p80 proteins were further studied in vitro using a bacterial growth inhibition test (for both liquid and solid cultures) and in vivo (using a bacterial growth inhibition test with the head-kidney tissues). Furthermore, BL21 (DE3) E. coli cells transformed with the recombinant pET28a-LmIL-12p40 vector were dramatically protected in response to metal toxicity and H₂O₂-related oxidative stress. In summary, this study will provide foundational information regarding the role of LmIL-12p40 in defending against various biotic and abiotic stresses in fishes, which should help to further clarify the functional mechanism of interleukins.

Crosstalks between mTORC1 and mTORC2 variagate cytokine signaling to control NK maturation and effector function

The metabolic checkpoint kinase mechanistic/mammalian target of rapamycin (mTOR) regulates natural killer (NK) cell development and function, but the exact underlying mechanisms remain unclear. Here, we show, via conditional deletion of Raptor (mTORC1) or Rictor (mTORC2), that mTORC1 and mTORC2 promote NK cell maturation in a cooperative and non-redundant manner, mainly by controlling the expression of Tbx21 and Eomes. Intriguingly, mTORC1 and mTORC2 regulate cytolytic function in an opposing way, exhibiting promoting and inhibitory effects on the anti-tumor ability and metabolism, respectively. mTORC1 sustains mTORC2 activity by maintaining CD122-mediated IL-15 signaling, whereas mTORC2 represses mTORC1-modulated NK cell effector functions by restraining STAT5-mediated SLC7A5 expression. These positive and negative crosstalks between mTORC1 and mTORC2 signaling thus variegate the magnitudes and kinetics of NK cell activation, and help define a paradigm for the modulation of NK maturation and effector functions.

The metabolic regulator protein family, mTOR, regulate natural killer (NK) cell development and function, but the underlying mechanism is unclear. Here, the authors show that Raptor/mTORC1 and Rictor/mTORC2 form a feedback crosstalk network to variegate cytokine and cellular signaling and modulate NK maturation and effector functions.

A Synthetic Disaccharide Derivative of Diphyllin, TAARD, Activates Human Natural Killer Cells to Secrete Interferon-Gamma via Toll-Like Receptor-Mediated NF-κB and STAT3 Signaling Pathways

Natural products and their derivatives have long been used as pharmacological agents in the fight against cancer. Human natural killer (NK) cells are critical in our immune system in that they are capable of destroying tumor cells directly. However, there are few reports that elucidate the role of natural products in activating NK cells. In this study, we discovered that a synthetic disaccharide derivative of diphyllin, 4-O-{[2′′,3′′,4′′-tri-O-acetyl-α-D-arabinopyranosyl-(1′′→4′)]-2′,3′-di-O-acetyl-α-L-rhamnopyranosyl}diphyllin (TAARD), can alone stimulate interferon (IFN)-γ secretion in primary human NK cells and the NKL cell line. Additionally, it had an additive effect with IL-12 or IL-15 on IFN-γ production, but little adverse effects on NK cells. Mechanistically, TAARD induced the phosphorylation of NF-κB and STAT3, resulting in their binding on the IFNG promoter, which was dependent on TLR1 and TLR3 signaling, respectively. STAT3 and NF-κB knockdown with lentivirus shRNA as well as the NF-κB-specific inhibitor, N-tosyl-l-phenylalaninechloromethyl ketone, significantly suppressed TAARD-induced IFN-γ generation in primary NK cells. Blockade of TLR1 and TLR3 with neutralizing antibodies considerably decreased TAARD-induced activation of NF-κB and STAT3, respectively, as well as IFN-γ generation in NK cells. Collectively, our data suggest that TAARD can induce NK cell IFN-γ production through TLR1-NF-κB and TLR3-STAT3 signaling pathways, rendering its potential use as an agent for cancer prevention or treatment.

The natural product chitosan enhances the anti-tumor activity of natural killer cells by activating dendritic cells

Natural products comprise an important class of biologically active molecules. Many of these compounds derived from natural sources exhibit specific physiologic or biochemical effects. An example of a natural product is chitosan, which is enriched in the shells of certain seafood that are frequently consumed worldwide. Like other natural products, chitosan has the potential for applications in clinical medicine and perhaps in cancer therapy. Toward this end, the immunomodulatory or anti-cancer properties of chitosan have yet to be reported. In this study, we discovered that chitosan enhanced the anti-tumor activity of natural killer (NK) cells by activating dendritic cells (DCs). In the presence of DCs, chitosan augmented IFN-γ production by human NK cells. Mechanistically, chitosan activated DCs to express pro-inflammatory cytokines such as interleukin (IL)-12 and IL-15, which in turn activated the STAT4 and NF-κB signaling pathways, respectively, in NK cells. Moreover, chitosan promoted NK cell survival, and also enhanced NK cell cytotoxicity against leukemia cells. Finally, a related in vivo study demonstrated that chitosan activated NK cells against B16F10 tumor cells in an immunocompetent syngeneic murine melanoma model. This effect was accompanied by in vivo upregulation of IL-12 and IL-15 in DCs, as well as increased IFN-γ production and cytolytic degranulation in NK cells. Collectively, our results demonstrate that chitosan activates DCs leading to enhanced capacity for immune surveillance by NK cells. We believe that our study has future clinical applications for chitosan in the prevention or treatment of cancer and infectious diseases.

IFN-γ Induces Gastric Cancer Cell Proliferation and Metastasis Through Upregulation of Integrin β3-Mediated NF-κB Signaling

Interferon γ (IFN-γ), a multifunctional cytokine, was upregulated in the resected gastric cancer tissue. However, whether IFN-γ is involved in the regulation of gastric cancer has not been well elucidated. Herein, we aimed to investigate the effects and mechanism of IFN-γ on gastric cancer. In this study, we found a vital role of IFN-γ in enhancing proliferation, inhibiting apoptosis, and promoting cell migration and invasion in gastric cancer cells SGC-7901 and MGC-803. Additionally, IFN-γ activated nuclear factor κB (NF-κB) signaling pathway by upregulating the phosphorylation expression of p65 and IκBα, and induced the expression of integrin β3 in vitro. Therefore, to further investigate the relationship between IFN-γ and integrin β3, SGC-7901 cells were transfected with integrin β3 siRNA. And then cells expressed lower cell viability, migration, and invasion rates, while cell apoptosis was significantly enhanced. Meanwhile, expression of integrin β3, MMP-2, MMP-9, and NF-κB, including p65 and IκBα, and the nuclear translocation of NF-κB/p65 were dramatically repressed, whereas IFN-γ significantly improved the effects. Moreover, in vivo, the experiment of xenograft model and pulmonary metastasis model also retarded in integrin β3 siRNA group. And the expression of integrin β3, MMP-2, MMP-9, and NF-κB was repressed. However, the treatment with IFN-γ improved tumor volume, lung/total weight, tumor nodules, and the protein expression described above compared with integrin β3 siRNA group. Overall, the results indicated that IFN-γ induces gastric cancer cell proliferation and metastasis partially through the upregulation of integrin β3-mediated NF-κB signaling. Hence, the inhibition of IFN-γ or integrin β3 may be the key for the treatment of gastric cancer.

The Search for Anticancer Agents from Tropical Plants

Many of the clinically used anticancer agents in Western medicine are derived from secondary metabolites found in terrestrial microbes, marine organisms, and higher plants, with additional compounds of this type being currently in clinical trials. If plants are taken specifically, it is generally agreed that the prospects of encountering enhanced small organic-molecule chemical diversity are better if tropical rather than temperate species are investigated in drug discovery efforts. Plant collection in tropical source countries requires considerable preparation and organization to conduct in a responsible manner that abides by the provisions of the 1992 Rio Convention of Biological Diversity and the 2010 Nagoya Protocol on Access to Genetic Resources. Correct taxonomic identifications and enhanced procedures for processing and documenting plant samples when collected in often difficult terrain are required. Phytochemical aspects of the work involve solvent fractionation, known compound dereplication, preliminary in vitro testing, and prioritization, leading to "activity-guided fractionation", compound structure determination, and analog development. Further evaluation of lead compounds requires solubility, formulation, preliminary pharmacokinetics, and in vivo testing in suitable models. Covering the work of the authors carried out in two sequential multidisciplinary, multi-institutional research projects, examples of very promising compounds discovered from plants acquired from Africa, Southeast Asia, the Americas, and the Caribbean region, and with potential anticancer activity will be mentioned. These include plant secondary metabolites of the diphyllin lignan, cyclopenta[b]benzofuran, triterpenoid, and tropane alkaloid types.

Application of ImmunoScore Model for the Differentiation between Active Tuberculosis and Latent Tuberculosis Infection as Well as Monitoring Anti-tuberculosis Therapy

Tuberculosis (TB) is a leading global public health problem. To achieve the end TB strategy, non-invasive markers for diagnosis and treatment monitoring of TB disease are urgently needed, especially in high-endemic countries such as China. Interferon-gamma release assays (IGRAs) and tuberculin skin test (TST), frequently used immunological methods for TB detection, are intrinsically unable to discriminate active tuberculosis (ATB) from latent tuberculosis infection (LTBI). Thus, the specificity of these methods in the diagnosis of ATB is dependent upon the local prevalence of LTBI. The pathogen-detecting methods such as acid-fast staining and culture, all have limitations in clinical application. ImmunoScore (IS) is a new promising prognostic tool which was commonly used in tumor. However, the importance of host immunity has also been demonstrated in TB pathogenesis, which implies the possibility of using IS model for ATB diagnosis and therapy monitoring. In the present study, we focused on the performance of IS model in the differentiation between ATB and LTBI and in treatment monitoring of TB disease. We have totally screened five immunological markers (four non-specific markers and one TB-specific marker) and successfully established IS model by using Lasso logistic regression analysis. As expected, the IS model can effectively distinguish ATB from LTBI (with a sensitivity of 95.7% and a specificity of 92.1%) and also has potential value in the treatment monitoring of TB disease.

LNGFR targets the Wnt/β-catenin pathway and promotes the osteogenic differentiation in rat ectomesenchymal stem cells

Considerable evidence has shown that the Wnt/β-catenin pathway is involved in osteogenic differentiation in various stem cells. However, the role of Wnt/β-catenin pathway in regulating the osteogenic differentiation of rat ectomesenchymal stem cells (EMSCs), which are considered to be the progenitors of dental mesenchymal stem cells, remains unknown. In this study, we demonstrated that nuclear β-catenin was upregulated during EMSC osteogenic differentiation. The Wnt signalling inhibitor IWR-1-endo inhibited EMSC osteogenic differentiation, while the Wnt signalling agonist SKL2001 promoted it. Moreover, nuclear β-catenin was further upregulated by the overexpression of low-affinity nerve growth factor receptor (LNGFR) during EMSC osteogenic differentiation. Further experiments demonstrated that LNGFR overexpression enhanced EMSC osteogenic differentiation, while LNGFR silencing decreased it. Additionally, IWR-1-endo attenuated LNGFR-enhanced EMSC osteogenic differentiation. Collectively, our data reveal that LNGFR targets the Wnt/β-catenin pathway and positively regulates EMSC osteogenic differentiation, suggesting that Wnt/β-catenin pathway may be involved in the development of teeth and that the targeting Wnt/β-catenin pathway may have great potential for applications in dental tissue engineering regeneration.

Black Raspberries Enhance Natural Killer Cell Infiltration into the Colon and Suppress the Progression of Colorectal Cancer

Natural killer (NK) cells are an essential component of innate immunity against cancer development. Many studies have been conducted to evaluate immune-modulating effects using dietary compounds. Our laboratory has been investigating the chemopreventive potential of black raspberries (BRBs) and previously demonstrated their beneficial modulation of genetic and epigenetic biomarkers in patients with colorectal cancer (CRC). The current study investigated their potential on modulating NK cells. To avoid the excessive inflammation caused by the dextran sulfate sodium (DSS) treatment that leads to colitis, we treated the mice with overnight DSS so that it would slightly irritate the colon but still promote colon carcinogenesis with 100% incidence in both the Apc^Min/+ mice and azoxymethane (AOM)-treated mice. A significant decrease of tissue-infiltrating NK cells along the progression of microadenoma-to-adenoma and adenoma-to-adenocarcinoma was observed in the Apc^Min/+ /DSS and AOM/DSS mice, respectively. Depletion of NK cells significantly promoted the development of CRC, suggesting a critical role of NK cells in combating CRC progression. BRBs significantly suppressed the CRC progression and increased the number of tissue-infiltrating NK cells in both mouse models. Moreover, we further determined BRBs' effects on NK cells in the human biopsy specimens collected from our previously completed clinical trial, in which CRC patients consumed BRBs for an average of 4 weeks during a presurgical window. We observed an increased number and an enhanced cytotoxicity of NK cells by BRB intervention. The current study provides evidence that BRBs have the potential to enhance the tumor immunesurveillance of NK cells that can be beneficial in the setting of CRC prevention and treatment.

Discovery of Anticancer Agents of Diverse Natural Origin

Recent progress is described in an ongoing collaborative multidisciplinary research project directed towards the purification, structural characterization, chemical modification, and biological evaluation of new potential natural product anticancer agents obtained from a diverse group of organisms, comprising tropical plants, aquatic and terrestrial cyanobacteria, and filamentous fungi. Information is provided on how these organisms are collected and processed. The types of bioassays are indicated in which initial extracts, chromatographic fractions, and purified isolated compounds of these acquisitions are tested. Several promising biologically active lead compounds from each major organism class investigated are described, and these may be seen to be representative of a very wide chemical diversity.

Genotoxic stress modulates the release of exosomes from multiple myeloma cells capable of activating NK cell cytokine production: Role of HSP70/TLR2/NF-kB axis

Exosomes are a class of nanovesicles formed and released through the late endosomal compartment and represent an important mode of intercellular communication. The ability of anticancer chemotherapy to enhance the immunogenic potential of malignant cells mainly relies on the establishment of the immunogenic cell death (ICD) and the release of damage-associated molecular patterns (DAMPs). Here, we investigated whether genotoxic stress could promote the release of exosomes from multiple myeloma (MM) cells and studied the immunomodulatory properties they exert on NK cells, a major component of the antitumor immune response playing a key role in the immunosurveillance of MM. Our findings show that melphalan, a genotoxic agent used in MM therapy, significantly induces an increased exosome release from MM cells. MM cell-derived exosomes are capable of stimulating IFNγ production, but not the cytotoxic activity of NK cells through a mechanism based on the activation of NF-κB pathway in a TLR2/HSP70-dependent manner. Interestingly, HSP70+ exosomes are primarily found in the bone marrow (BM) of MM patients suggesting that they might have a crucial immunomodulatory action in the tumor microenvironment. We also provide evidence that the CD56high NK cell subset is more responsive to exosome-induced IFNγ production mediated by TLR2 engagement. All together, these findings suggest a novel mechanism of synergism between chemotherapy and antitumor innate immune responses based on the drug-promotion of nanovesicles exposing DAMPs for innate receptors.

Sustained elevation of NF-κB activity sensitizes offspring of maternal inflammation to hypertension via impairing PGC-1α recovery

Growing evidence has demonstrated that maternal detrimental factors, including inflammation, contribute to the development of hypertension in the offspring. The current study found that offspring subjected to prenatal exposure of inflammation by lipopolysaccharide (LPS) challenge during the second semester showed significantly increased systolic blood pressure. In addition, these offspring also displayed augmented vascular damage and reactive oxygen species (ROS) levels in thoracic aortas when challenged with deoxycorticosterone acetate and high-salt diet (DOCA-salt). Interestingly, the antioxidant N-acetyl-L-cysteine markedly reversed these changes. Mechanistically, prenatal LPS exposure led to pre-existing elevated peroxisome proliferators-activated receptor-γ co-activator (PGC)-1α, a critical master of ROS metabolism, which up-regulated the ROS defense capacity and maintained the balance of ROS generation and elimination under resting state. However, continued elevation of NF-κB activity significantly suppressed the rapid recovery of PGC-1α expression response to DOCA-salt challenge in offspring that underwent prenatal inflammatory stimulation. This was further confirmed by using a NF-κB inhibitor (N-p-Tosyl-L-phenylalanine chloromethyl ketone) that restored PGC-1α recovery and prevented blood pressure elevation induced by DOCA-salt. Our results suggest that maternal inflammation programmed proneness to NF-κB over-activation which impaired PGC-1α-mediated anti-oxidant capacity resulting in the increased sensitivity of offspring to hypertensive damage.

Modulation of Toll-like receptor signaling in innate immunity by natural products

For centuries, natural products and their derivatives have provided a rich source of compounds for the development of new immunotherapies in the treatment of human disease. Many of these compounds are currently undergoing clinical trials, particularly as anti-oxidative, anti-microbial, and anti-cancer agents. However, the function and mechanism of natural products in how they interact with our immune system has yet to be extensively explored. Natural immune modulators may provide the key to control and ultimately defeat disorders affecting the immune system. They can either up- or down-regulate the immune response with few undesired adverse effects. In this review, we summarize the recent advancements made in utilizing natural products for immunomodulation and their important molecular targets, members of the Toll-like receptor (TLR) family, in the innate immune system.

Maternal inflammation activated ROS-p38 MAPK predisposes offspring to heart damages caused by isoproterenol via augmenting ROS generation

Maternal inflammation contributes to the increased incidence of adult cardiovascular disease. The current study investigated the susceptibility of cardiac damage responding to isoproterenol (ISO) in adult offspring that underwent maternal inflammation (modeled by pregnant Sprague-Dawley rats with lipopolysaccharides (LPS) challenge). We found that 2 weeks of ISO treatment in adult offspring of LPS-treated mothers led to augmented heart damage, characterized by left-ventricular systolic dysfunction, cardiac hypertrophy and myocardial fibrosis. Mechanistically, prenatal exposure to LPS led to up-regulated expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, antioxidant enzymes, and p38 MAPK activity in left ventricular of adult offspring at resting state. ISO treatment exaggerated ROS generation, p38 MAPK activation but down-regulated reactive oxygen species (ROS) elimination capacity in the left ventricular of offspring from LPS-treated mothers, while antioxidant N-acetyl-L-cysteine (NAC) reversed these changes together with improved cardiac functions. The p38 inhibitor SB202190 alleviated the heart damage only via inhibiting the expression of NADPH oxidases. Collectively, our data demonstrated that prenatal inflammation programs pre-existed ROS activation in the heart tissue, which switches on the early process of oxidative damages on heart rapidly through a ROS-p38 MAPK-NADPH oxidase-ROS positive feedback loop in response to a myocardial hypertrophic challenge in adulthood.

Post-Natal Inhibition of NF-κB Activation Prevents Renal Damage Caused by Prenatal LPS Exposure

Prenatal exposure to an inflammatory stimulus has been shown to cause renal damage in offspring. Our present study explored the role of intra-renal NF-κB activation in the development of progressive renal fibrosis in offspring that underwent prenatal exposure to an inflammatory stimulus. Time-dated pregnant rats were treated with saline (control group) or 0.79 mg/kg lipopolysaccharide (LPS) through intra-peritoneal injection on gestational day 8, 10 and 12. At the age of 7 weeks, offspring from control or LPS group were treated with either tap water (Con+Ve or LPS+Ve group) or pyrollidine dithiocarbamate (PDTC, 120mg/L), a NF-κB inhibitor, via drinking water starting (Con+PDTC or LPS+PDTC group), respectively, till the age of 20 or 68 weeks. The gross structure of kidney was assessed by hematoxylin-eosin, periodic acid–Schiff staining and Sirius red staining. The expression levels of TNF-α, IL-6, α-smooth muscle actin (α-SMA) and renin-angiotensin system (RAS) genes were determined by real time polymerase chain reaction and/or immunohistochemical staining. Our data showed that post-natal persistent PDTC administration efficiently repressed intra-renal NF-κB activation, TNF-α and IL-6 expression. Post-natal PDTC also prevented intra-renal glycogen deposition and collagenous fiber generation as evident by the reduced expression of collagen III and interstitial α-SMA in offspring of prenatal LPS exposure. Furthermore, post-natal PDTC administration reversed the intra-renal renin-angiotensin system (RAS) over-activity in offspring of prenatal LPS exposure. In conclusion, prenatal inflammatory exposure results in offspring’s intra-renal NF-κB activation along with inflammation which cross-talked with excessive RAS activation that caused exacerbation of renal fibrosis and dysfunction in the offspring. Thus, early life prevention of NF-κB activation may be a potential preventive strategy for chronic renal inflammation and progressive renal damage.

Anti-influenza virus effects of crude phenylethanoid glycosides isolated from ligustrum purpurascens via inducing endogenous interferon-γ

ETHNOPHARMACOLOGICAL RELEVANCE

Ligustrum purpurascens Y.C. Yang (Oleaceae) is traditionally recorded as "Ku Ding Cha", a kind of functional tea in southern China for about two thousand years, which has been reported with sore throat alleviating and pathogenic heat expelling effects. However, there are no scientific studies demonstrating its antiviral activity.

THE AIM OF THE STUDY

This study is aimed at investigating the anti-influenza virus effects of phenylethanoid glycosides isolated from L. purpurascens (LPG) as well as its corresponding mechanisms.

MATERIALS AND METHODS

In vitro, hemagglutination assay was employed to detect the influenza virus titer; In vivo, C57BL/6J mice were given oral administration of LPG (100mg/kg, 300mg/kg, 900mg/kg) or ribavirin (100mg/kg) once daily for 5 successive days. Meanwhile, on the second day, mice were infected intranasally (i.n.) with A/FM/1/47 H1N1 virus. Mice survival rate and other clinical index were monitored for 15 days. Infected mice were sacrificed to measure the lung lesion and stained with hematoxylin-eosin. Flow cytometry analyses spleen lymphocytes and interferon-γ (IFN-γ) level. The IFN-γ knockout mice (IFN-γ(-/-) mice, C57BL/6J) which had been verified lacking IFN-γ through Western Blot, were applied in the death-protection test to identify the role of IFN-γ played in LPG antiviral effect.

RESULTS

In vitro, LPG at 0.5mg/ml inhibited Influenza A Virus H1N1 type (H1N1) infection of MDCK cells. In vivo, LPG at 300 and 900mg/kg significantly decreased the mouse lung index (p<0.05), alleviated influenza-induced lethality and clinical symptoms, and therefore enhanced mouse survival (p<0.05). More detailed experiments demonstrated that antiviral cytokine IFN-γ was involved in the antiviral effect of LPG. Flow cytometric analysis revealed that LPG (900mg/kg) significantly induced secretion of IFN-γ by splenic CD4(+) and CD8(+) cells (p<0.05). Moreover, LPG (900mg/kg) protected wild-type C57BL/6J mice from H1N1 injury, whereas LPG-mediated survival protection disappeared in IFN-γ(-/-) mice.

CONCLUSION

These results suggest that up-regulating endogenous IFN-γ by LPG may represent a novel therapeutic approach for H1N1 infection.

Prenatal inflammation-induced NF-κB dyshomeostasis contributes to renin-angiotensin system over-activity resulting in prenatally programmed hypertension in offspring

Studies involving the use of prenatally programmed hypertension have been shown to potentially contribute to prevention of essential hypertension (EH). Our previous research has demonstrated that prenatal inflammatory stimulation leads to offspring's aortic dysfunction and hypertension in pregnant Sprague-Dawley rats challenged with lipopolysaccharide (LPS). The present study found that prenatal LPS exposure led to NF-κB dyshomeostasis from fetus to adult, which was characterized by PI3K-Akt activation mediated degradation of IκBα protein and impaired NF-κB self-negative feedback loop mediated less newly synthesis of IκBα mRNA in thoracic aortas (gestational day 20, postnatal week 7 and 16). Prenatal or postnatal exposure of the IκBα degradation inhibitor, pyrollidine dithiocarbamate, effectively blocked NF-κB activation, endothelium dysfunction, and renin-angiotensin system (RAS) over-activity in thoracic aortas, resulting in reduced blood pressure in offspring that received prenatal exposure to LPS. Surprisingly, NF-κB dyshomeostasis and RAS over-activity were only found in thoracic aortas but not in superior mesenteric arteries. Collectively, our data demonstrate that the early life NF-κB dyshomeostasis induced by prenatal inflammatory exposure plays an essential role in the development of EH through triggering RAS over-activity. We conclude that early life NF-κB dyshomeostasis is a key predictor of EH, and thus, NF-κB inhibition represents an effective interventional strategy for EH prevention.

Transcription factor Foxo1 is a negative regulator of natural killer cell maturation and function

Little is known about the role of negative regulators in controlling natural killer (NK) cell development and effector functions. Foxo1 is a multifunctional transcription factor of the forkhead family. Using a mouse model of conditional deletion in NK cells, we found that Foxo1 negatively controlled NK cell differentiation and function. Immature NK cells expressed abundant Foxo1 and little Tbx21 relative to mature NK cells, but these two transcription factors reversed their expression as NK cells proceeded through development. Foxo1 promoted NK cell homing to lymph nodes by upregulating CD62L expression and inhibited late-stage maturation and effector functions by repressing Tbx21 expression. Loss of Foxo1 rescued the defect in late-stage NK cell maturation in heterozygous Tbx21(+/-) mice. Collectively, our data reveal a regulatory pathway by which the negative regulator Foxo1 and the positive regulator Tbx21 play opposing roles in controlling NK cell development and effector functions.

Cytotoxic and natural killer cell stimulatory constituents of Phyllanthus songboiensis

A dichapetalin-type triterpenoid and a dibenzylbutyrolactone-type lignan, together with five known lignans, a known aromatic diterpenoid, and a known acylated phytosterol, were isolated from the aerial parts of Phyllanthus songboiensis, collected in Vietnam. Their structures were determined by interpretation of the spectroscopic data, and the inhibitory activity toward HT-29 human colon cancer cells of all isolates was evaluated by a cytotoxicity assay. The known arylnaphthalene lignan, (+)-acutissimalignan A, was highly cytotoxic toward HT-29 cells, with an IC50 value of 19 nM, but this compound was inactive as a DNA topoisomerase IIα (topo IIα) poison. The known phytosterol, (-)-β-sitosterol-3-O-β-D-(6-O-palmitoyl)glucopyranoside, was found to stimulate natural killer (NK) cells at a concentration of 10μM in the presence of interleukin 12 (IL-12).