Junling Shi

Biological activity of lipopeptides from Bacillus

The lipopeptides of Bacillus are small metabolites that contain a cyclic structure formed by 7–10 amino acids (including 2–4 d-amino acids) and a beta-hydroxy fatty acid with 13–19 C atoms. These lipopeptides exhibit a variety of biological activities, including interactions with biofilms, and anti-fungal, anti-inflammatory, anti-tumor, anti-virus, and anti-platelet properties. The multiple activities of lipopeptides have stimulated significant interest in the exploitation of these lipopeptides for use as antibiotics, feed additives, anti-tumor agents, urgent thrombolytic therapeutic agents, and drug delivery systems. Understanding the natural function of these structurally diverse lipopeptides in Bacillus provides insight into microbial regulatory programs and is required for efficient development of more effective products. Currently, there is still insufficient knowledge of the direct target of these lipopeptides, and continued efforts are needed to enhance their biosynthesis efficiency for industrial applications.

Capacity of lactic acid bacteria in immunity enhancement and cancer prevention

Lactic acid bacteria are associated with the human gastrointestinal tract. They are important for maintaining the balance of microflora in the human gut. An increasing number of published research reports in recent years have denoted the importance of producing interferon-gamma and IgA for treatment of disease. These agents can enhance the specific and nonspecific immune systems that are dependent on specific bacterial strains. The mechanisms of these effects were revealed in this investigation, where the cell walls of these bacteria were modulated by the cytokine pathways, while the whole bacterial cell mediated the host cell immune system and regulated the production of tumor necrosis factors and interleukins. A supplement of highly active lactic acid bacteria strains provided significant potential to enhance host’s immunity, offering prevention from many diseases including some cancers. This review summarizes the current understanding of the function of lactic acid bacteria immunity enhancement and cancer prevention.

Multiple effects of IL-21 on human NK cells in ex vivo expansion.

Natural killer (NK) cells (CD56(+)CD3(-)) are large, granular immunocytes that play a very pivotal role in the anti-inflammatory response and tumor surveillance. As an ideal cytotoxic lymphocyte (CTL), NK cells have attracted much attention in clinical trials. However, an insufficient number and their limited life span are bottlenecks that limit the application of NK cells in adoptive immunotherapy. Interleukins such as IL-2, IL-15 and IL-18 are recognized as factors that stimulate NK cells and have been used in NK cells ex vivo expansion. Similar to IL-2 and IL-15, IL-21 is a common γ-chain cytokine that is important in NK cell activation, maturation and proliferation. The present study aims to assess the effects of membrane-bound and soluble IL-21 on primary human NK cells during ex vivo expansion. IL-21 was found to have multiple effects on NK cells, increasing their cytotoxicity in a concentration-dependent manner by up-regulating IFN-γ and Granzyme-B expression. Nevertheless, at a high concentration (50 ng/mL), IL-21 curtailed the life span of NK cells by significantly inducing apoptosis. Moreover, when treated with IL-21, the number of NKT (CD56(+)CD3(+)) cells increased among peripheral blood mononuclear cells (PBMCs) during ex vivo expansion in a concentration-dependent manner. IL-21 also promoted expanded cells to enter into S phase of the cell cycle during the first to second weeks of culture. All these results suggest that IL-21 has multiple effects on NK cell development and functions. More attention should be given to the dosage and multiple effects of IL-21 when it was applied to NK cells in ex vivo expansion.

Effects of polysaccharide from mycelia of Ganoderma lucidum on intestinal barrier functions of rats

The intestinal mucosal barriers play essential roles not only in the digestion and absorption of nutrients, but also the innate defense against most intestinal pathogens. In the present study, polysaccharide from the mycelia of Ganoderma lucidum was given via oral administration to rats (100mg/kg body weight, 21days) to investigate its effects on intestinal barrier functions, including the mechanical barrier, immunological barrier and biological barrier function. It was found that the polysaccharide administration could significantly up-regulate the expression of occludin, nuclear factor-κB p65 (NF-κB p65) and secretory immunoglobulin A (SIgA) in ileum, markedly improve the levels of interferon-γ (IFN-γ), interleukin-2 (IL-2), and IL-4, and decrease the level of diamine oxidase (DAO) in serum. Meanwhile, rats from the polysaccharide group showed significant higher microbiota richness in cecum as reflected by the Chao 1 index compared with the control group. Moreover, the polysaccharide decreased the Firmicutes-to-Bacteroidetes ratio. Our results indicated that the polysaccharide from the mycelia of G. lucidum might be used as functional agent to regulate the intestinal barrier functions.

Strategies for enhancing resveratrol production and the expression of pathway enzymes

Trans-resveratrol (trans-3,5,4′-trihydroxystilbene) is one of the most promising stilbenes, a type of natural phenol that is produced naturally by some plant species in response to stress. Resveratrol exhibits multiple bioactivities and is used in the agriculture, medical, food, and cosmetic industries due to its antitumor, anti-inflammatory, cardioprotective, and antioxidant properties. Due to the increasing demand, an active area of investigation is the use of plant cell culture and metabolic engineering techniques to produce large quantities of active resveratrol. However, most recent studies have focused on the efficiency of synthesizing resveratrol in vitro, but have not investigated the contributions of the transcriptional activities of the genes encoding the related enzymes in the biosynthesis pathway. This article reviews recently developed methods for the biosynthesis of resveratrol and comprehensively reviews the current state of knowledge of the function of the key pathway enzymes in resveratrol synthesis. Approaches for enhancing resveratrol production, such as introducing non-pathway genes and co-localizing enzymes are described in detail.

Concentration-dependent biphasic effects of resveratrol on human natural killer cells in vitro.

Resveratrol (RES) is a polyphenol phytoalexin from plants, which has been reported to possess a variety of biological effects. The properties of RES on human natural killer (NK) cells were assessed in this study. Results showed that RES has concentration-dependent biphasic effects on NK cells. In high concentration (50 μM), RES can inhibit viability and promoted apoptosis of NK cells and human lymphoblastoid T (Jurkat) cells, which may affect the caspase signaling pathway. The Jurkat cells were more sensitive than NK cells on the RES caused cell death. However, when the concentration range reduced from 3.13 to 1.56 μM, RES showed the positive effects on NK cells by increasing the NK cells cytotoxicity via up-regulating the expression of NKG2D and IFN-γ (in mRNA and protein levels). These results indicated that one needs to pay more attention to the dosage and biphasic effects when RES was applied as antitumor drugs or health products.

Cholesterol-Lowering Effects and Mechanisms in View of Bile Acid Pathway of Resveratrol and Resveratrol Glucuronides

Resveratrol (Res) was previously reported to be capable of lowering plasma TC and LDL-C. The mechanism behind Res is not clearly understood, although it is presumed to have an effect on bile acid metabolism in the liver: a significant way in eliminating cholesterol from the body. As one of the major metabolites of Res in the liver, resveratrol glucuronides (Gres) is suspected to also contribute to the overall cholestrol-lowering activity of Res, which needs to be studied. In this research, when HepG2 steatosis hepatic cells were treated with Res and Gres at different concentration levels, Res and Gres showed similar activity in lowering cellular TC content. The presence of Res and Gres caused a significant increase in hepatic CYP7A1 and BSEP, indicating the increase in the synthesis and efflux of bile acids, respectively. The reduction of HMG-CoAR tied to a decrease in de novo synthesis of cholesterol and the increase of ABCG5 suggested the increase of direct efflux of cholesterol. All above variations reduced the hepatic cholesterol level, which triggered the significant enhancement of LDLR, illustrating the improvement of clearance of LDL-C from the plasma and prevention of atherosclerosis. Overall, this study demonstrated both Res and Gres might have capabilities in lowering hepatic cholesterol through increasing in the synthesis and efflux of bile acids, and decreasing in synthesis and increasing in the efflux of cholesterol. Gres would have preferred potential than Res because of its lower cytotoxicity, which indicated that the action of the metabolites should also be considered in the future studies.

Telomere reverse transcriptase (TERT) rs2735940 increases cancer risk.

Background Telomerase reverse transcriptase (TERT) rs2735940 polymorphism was found to be associated with increased cancer risk. However, recent studies reported controversial results. The aim of our study was to detect its relationship with cancer risk. Material/Methods EMBASE and PubMed databases were searched for all publications until October 2014. ORs and 95% CIs were applied to investigate the association in the random-effects model. Results Thirteen case-control studies with 19385 cases and 17558 controls were included in this study. We found a significant association between cancer risk and TERT rs2735940 polymorphism (OR=1.06, 95% CI 1.02–1.11, P=0.005). In the subgroup analysis by ethnicity, a marginal association was found in Caucasians (OR=1.05, 95% CI 1.00–1.10, P=0.05), but not in Asians (OR=1.01, 95% CI 0.82–1.24, P=0.93). In the subgroup analysis by cancer site, this polymorphism was significantly associated with lung cancer risk (OR=1.08, 95% CI 1.02–1.13, P=0.004). Conclusions TERT rs2735940 polymorphism was significantly associated with cancer risk, especially lung cancer.

Fungal silver nanoparticles: synthesis, application and challenges

Abstract Purpose: This paper aims to summarize recent developments regarding the synthesis, application and challenges of fungal AgNPs. Possible methods to overcome the challenge of synthesis and reduce the toxicity of AgNPs have been discussed. Materials and methods: This review consults and summary a large number of papers. Results: Silver nanoparticles (AgNPs) have great potential in many areas, as they possess multiple novel characteristics. Conventional methods for AgNPs biosynthesis involve chemical agents, causing environmental toxicity and high energy consumption. Fungal bioconversion is a simple, low-cost and energy-efficient biological method, which could successfully be used for AgNPs synthesis. Fungi can produce enzymes that act as both reducing and capping agents, to form stable and shape-controlled AgNPs. Conclusions: AgNPs have great potential in the medical and food industries, due to their antimicrobial, anticancer, anti-HIV, and catalytic activities. However, the observed in vitro and in vivo toxicity poses considerable challenges in the synthesis and application of AgNPs.

Validation of reference genes for normalization of gene expression by qRT-PCR in a resveratrol-producing entophytic fungus ( Alternaria sp. MG1)

Alternaria sp. MG1, an endophytic fungus isolated from Vitis vinifera, can independently produce resveratrol, indicating that this species contains the key genes for resveratrol biosynthesis. Identification of these key genes is essential to understand the resveratrol biosynthesis pathway in this strain, which is currently unknown in microorganisms. qRT-PCR is an efficient and widely used method to identify the key genes related to unknown pathways at the level of gene expression. Verification of stable reference genes in this strain is essential for qRT-PCR data normalization, although results have been reported for other Alternaria sp. strains. In this study, nine candidate reference genes including TUBA, EF1, EF2, UBC, UFD, RPS5, RPS24, ACTB and 18S were evaluated for expression stability in a diverse set of six samples representing different growth periods. We compared cell culture conditions and an optimized condition for resveratrol production. The comparison of the results was performed using four statistical softwares. A combination of TUBA and EF1 was found to be suitable for normalization of Alternaria sp. MG1 in different developmental stages, and 18S was found to be the least stable. The reference genes verified in this study will facilitate further research to explore gene expression and molecular mechanisms as well as the improvement of secondary metabolite yields in Alternaria sp. MG1. To our knowledge, this is the first validation of reference genes in Alternaria with the capability to produce resveratrol. Additionally, these results provide useful guidelines for the selection of reference genes in other Alternaria species.