COMPARISON OF NEURAMINIDASE ACTIVITY OF INFLUENZA A VIRUS SUBTYPE H5N1 AND H1N1 USING REVERSE GENETICS VIRUS

Abstract. Neuraminidase (NA) is an envelope surface glycoprotein of influenza A viruses. It cleaves α-(2,3) or α-(2,6) glycosidic linkage between a terminal sialic acid residue of the host cell receptor and hemagglutinin of the viral envelope, thus releasing viral progeny from the infected cell. In this study, a reassortant virus (H1N1-NA-H5N1) containing the NA gene from A/duck/Phitsanulok/ NIAH6-5-0001/2007 (H5N1) virus and seven remaining genetic segments from A/ Puerto Rico/8/1934 (H1N1) was constructed using reverse genetic technique. NA activity of H1N1-NA-H5N1 virus was lower than that of A/Puerto Rico/8/1934 (H1N1), and NA activity of A/duck/Phitsanulok/NIAH6-5-0001/2007 study (H5N1) was the lowest among them (p < 0.05). To our knowledge, this is the first comparative study of NA activity of H1N1 and H5N1 virus using reverse genetic technique. It also indicates that the NA gene may be expressed at a higher level in the H1N1 infected cell than the H5N1 infected cell

Anti-CD3 Fab Fragments Enhance Tumor Killing by Human γδ T Cells Independent of Nck Recruitment to the γδ T Cell Antigen Receptor

T lymphocytes expressing the γδ T cell receptor (γδ TCR) can recognize antigens expressed by tumor cells and subsequently kill these cells. γδ T cells are indeed used in cancer immunotherapy clinical trials. The anti-CD3ε antibody UCHT1 enhanced the in vitro tumor killing activity of human γδ T cells by an unknown molecular mechanism. Here, we demonstrate that Fab fragments of UCHT1, which only bind monovalently to the γδ TCR, also enhanced tumor killing by expanded human Vγ9Vδ2 γδ T cells or pan-γδ T cells of the peripheral blood. The Fab fragments induced Nck recruitment to the γδ TCR, suggesting that they stabilized the γδ TCR in an active CD3ε conformation. However, blocking the Nck-CD3ε interaction in γδ T cells using the small molecule inhibitor AX-024 neither reduced the γδ T cells’ natural nor the Fab-enhanced tumor killing activity. Likewise, Nck recruitment to CD3ε was not required for intracellular signaling, CD69 and CD25 up-regulation, or cytokine secretion by γδ T cells. Thus, the Nck-CD3ε interaction seems to be dispensable in γδ T cells

Anti-CD3 Fab Fragments Enhance Tumor Killing by Human γδ T Cells Independent of Nck Recruitment to the γδ T Cell Antigen Receptor

T lymphocytes expressing the γδ T cell receptor (γδ TCR) can recognize antigens expressed by tumor cells and subsequently kill these cells. γδ T cells are indeed used in cancer immunotherapy clinical trials. The anti-CD3ε antibody UCHT1 enhanced the in vitro tumor killing activity of human γδ T cells by an unknown molecular mechanism. Here, we demonstrate that Fab fragments of UCHT1, which only bind monovalently to the γδ TCR, also enhanced tumor killing by expanded human Vγ9Vδ2 γδ T cells or pan-γδ T cells of the peripheral blood. The Fab fragments induced Nck recruitment to the γδ TCR, suggesting that they stabilized the γδ TCR in an active CD3ε conformation. However, blocking the Nck-CD3ε interaction in γδ T cells using the small molecule inhibitor AX-024 neither reduced the γδ T cells' natural nor the Fab-enhanced tumor killing activity. Likewise, Nck recruitment to CD3ε was not required for intracellular signaling, CD69 and CD25 up-regulation, or cytokine secretion by γδ T cells. Thus, the Nck-CD3ε interaction seems to be dispensable in γδ T cells

Protective effect of silk lutein on ultraviolet B-irradiated human keratinocytes

Carotenoids are efficient antioxidants that are of great importance for human health. Lutein and zeaxanthin are carotinoids present in high concentrations in the human retina which are involved in the photoprotection of the human eye. Lutein may also protect the skin from ultraviolet (UV)-induced damage. The present study investigated the protective effect of lutein extracted from yellow silk cocoons of Bombyx mori on human keratinocytes against UVB irradiation. A human keratinocyte cell line and primary human keratinocytes were used to investigate the UVB protection effects of silk lutein and plant lutein. Silk lutein showed no cytotoxicity to keratinocytes. Treatment with silk lutein prior to UVB irradiation enhanced cell viability and cell proliferation, and reduced cell apoptosis. The protective effects of silk lutein may be superior to those of plant lutein. Silk lutein may have a benefit for protection of keratinocytes against UVB-irradiation

Nitro Dihydrocapsaicin, a Non-Pungent Capsaicin Analogue, Inhibits Cellular Senescence of Lens Epithelial Cells via Upregulation of SIRT1

Diabetic cataracts are a common complication that can cause blindness among patients with diabetes mellitus. A novel nitro dihydrocapsaicin (NDHC), a capsaicin analog, was constructed to have a non-pungency effect. The objective of this research was to study the effect of NDHC on human lens epithelial (HLE) cells that lost function from hyperglycemia. HLE cells were pretreated with NDHC before an exposure to high glucose (HG) conditions. The results show that NDHC promoted a deacceleration of cellular senescence in HLE cells. This inhibition of cellular senescence was characterized by a delayed cell growth and lower production of reactive oxygen species (ROS) as well as decreased SA-β-galactosidase activity. Additionally, the expression of Sirt1 protein sharply increased, while the expression of p21 and phospho-p38 proteins decreased. These findings provide evidence that NDHC could exert a pharmacologically protective effect by inhibiting the senescence program of lens cells during diabetic cataracts

The selective target of capsaicin on FASN expression and de novo fatty acid synthesis mediated through ROS generation triggers apoptosis in HepG2 cells.

The inhibition of the mammalian de novo synthesis of long-chain saturated fatty acids (LCFAs) by blocking the fatty acid synthase (FASN) enzyme activity in tumor cells that overexpress FASN can promote apoptosis, without apparent cytotoxic to non-tumor cells. The present study aimed to focus on the potent inhibitory effect of capsaicin on the fatty acid synthesis pathway inducing apoptosis of capsaicin in HepG2 cells. The use of capsaicin as a source for a new FASN inhibitor will provide new insight into its possible application as a selective anti-cancer therapy. The present findings showed that capsaicin promoted apoptosis as well as cell cycle arrest in the G0/G1 phase. The onset of apoptosis was correlated with a dissipation of mitochondrial membrane potential (ΔΨm). Apoptotic induction by capsaicin was mediated by inhibition of FASN protein expression which was accompanied by decreasing its activity on the de novo fatty acid synthesis. The expression of FASN was higher in HepG2 cells than in normal hepatocytes that were resistant to undergoing apoptosis following capsaicin administration. Moreover, the inhibitory effect of capsaicin on FASN expression and activity was found to be mediated by an increase of intracellular reactive oxygen species (ROS) generation. Treatment of HepG2 cells with capsaicin failed to alter ACC and ACLY protein expression, suggesting ACC and ACLY might not be the specific targets of capsaicin to induce apoptosis. An accumulation of malonyl-CoA level following FASN inhibition represented a major cause of mitochondrial-dependent apoptotic induction instead of deprivation of fatty acid per se. Here, we also obtained similar results with C75 that exhibited apoptosis induction by reducing the levels of fatty acid without any change in the abundance of FASN expression along with increasing ROS production. Collectively, our results provide novel evidence that capsaicin exhibits a potent anti-cancer property by targeting FASN protein in HepG2 cells

Effects of silk sericin on the proliferation and apoptosis of colon cancer cells

Sericin is a silk protein woven from silkworm cocoons (Bombyx mori). In animal model, sericin has been reported to have anti-tumoral action against colon cancer. The mechanisms underlying the activity of sericin against cancer cells are not fully understood. The present study investigated the effects of sericin on human colorectal cancer SW480 cells compared to normal colonic mucosal FHC cells. Since the size of the sericin protein may be important for its activity, two ranges of molecular weight were tested. Sericin was found to decrease SW480 and FHC cell viability. The small sericin had higher anti-proliferative effects than that of the large sericin in both cell types. Increased apoptosis of SW480 cells is associated with increased caspase-3 activity and decreased Bcl-2 expression. The anti-proliferative effect of sericin was accompanied by cell cycle arrest at the S phase. Thus, sericin reduced SW480 cell viability by inducing cell apoptosis via caspase-3 activation and down-regulation of Bcl-2 expression. The present study provides scientific data that support the protective effect of silk sericin against cancer cells of the colon and suggests that this protein may have significant health benefits and could potentially be developed as a dietary supplement for colon cancer prevention

The effect of dietary sericin on rats

ABSTRACT: Dietary proteins have been reported to be beneficial for lipid metabolism, tissue growth, development, and repair, as well as immune response. The interactions of dietary proteins and their digested products may regulate the physiology and metabolism of the gastrointestinal tract. However, proteins are largely digested before reaching the large intestine. The present study investigated the use of the non-dietary protein, silk sericin, in rats. Rats were fed either with casein or sericin proteins. Their body weight, food consumption, and complete blood count were measured. The results showed that during the experimental periods, rats fed with casein and sericin diets had no significant changes on body weight, food consumption, or complete blood count. Sericin-fed rats had a significantly decreased CD8a and CD80 positive cells when compared with standard casein protein. In conclusion, dietary proteins may have a differential impact on the leukocyte profile. The mechanisms underlying these changes are not clear but they might be due to the different amino acid compositions of the proteins studied