Oral administration of Euglena gracilis Z and its carbohydrate storage substance provides survival protection against influenza virus infection in mice.

Euglena gracilis Z is a micro-algae that is used as a food or nutritional supplement. Paramylon, the carbohydrate storage substance of Euglena gracilis Z has ß-1, 3-glucan structure. Euglena gracilis Z and paramylon are reported to affect the immune system. In this study, we investigated the protective effects of Euglena gracilis Z and paramylon against influenza virus infection in mice. Euglena gracilis Z and paramylon were administered to mice as a 2% dietary mixture ad libitum. At 2 weeks after initiation of dietary administration, mice were infected intranasally with influenza virus A/PR/8/34 (H1N1). Survival rate was monitored 10 days after infection. In addition, we performed virus titer and cytokine profiles in the lung. High survival rates were observed for Euglena gracilis Z and paramylon-treated groups compared to the control group. Significantly lower virus titer in the lung was observed in the Euglena gracilis Z and paramylon-treated groups compared to the control group from day 1 after infection. Higher amount of IL-1ß, IL-6, IL-12 (p70), IFN-γ, and IL-10 was observed in the paramylon groups compared to the control group. Our data therefore reveals a novel immunoregulatory role of the Euglena gracilis Z and paramylon which provides protection against influenza virus infection.

Dietary wolfberry supplementation enhances the protective effect of flu vaccine against influenza challenge in aged mice.

Current vaccines for influenza do not fully protect the aged against influenza infection. Although wolfberry (goji berry) has been shown to improve immune response, including enhanced antibody production, after vaccination in the aged, it is not known if this effect would translate to better protection after influenza infection, nor is its underlying mechanism well understood. To address these issues, we conducted a study using a 2 × 2 design in which aged male mice (20-22 mo) were fed a control or a 5% wolfberry diet for 30 d, then immunized with an influenza vaccine or saline (control) on days 31 and 52 of the dietary intervention, and finally challenged with influenza A/Puerto Rico/8/34 virus. Mice fed wolfberry had higher influenza antibody titers and improved symptoms (less postinfection weight loss) compared with the mice treated by vaccine alone. Furthermore, an in vitro mechanistic study showed that wolfberry supplementation enhanced maturation and activity of antigen-presenting dendritic cells (DCs) in aged mice, as indicated by phenotypic change in expression of DC activation markers major histocompatibility complex class II, cluster of differentiation (CD) 40, CD80, and CD86, and functional change in DC production of cytokines interleukin-12 and tumor necrosis factor-α as well as DC endocytosis. Also, adoptive transfer of wolfberry-treated bone marrow DCs (loaded with ovalbumin(323-339)-peptide) promoted antigen-specific T cell proliferation as well as interleukin-4 and interferon-γ production in CD4(+) T cells. In summary, our data indicate that dietary wolfberry enhances the efficacy of influenza vaccination, resulting in better host protection to prevent subsequent influenza infection; this effect may be partly attributed to improved DC function.

Efficacy of oral administration of heat-killed probiotics from Mongolian dairy products against influenza infection in mice: alleviation of influenza infection by its immunomodulatory activity through intestinal immunity.

Some probiotics possess immunomodulatory activities and have been used as complementary and alternative medicines. We previously found that 10 lactic acid bacteria (LAB) strains isolated from traditional Mongolian dairy products showed probiotic potential in vitro. In this study, we assessed the immunomodulatory activity of 10 LABs on influenza virus (IFV) infection in relation to their efficacies in IFV-infected mice. In an intranasal IFV infection model in mice, oral administration of boiled Lactobacillus plantarum 06CC2 strain (20mg/mouse), one of the 10 LABs, twice daily for 10 days starting two days before infection was significantly effective in protecting the body weight loss of infected mice, reducing virus yields in the lungs on days 2, 4, and 6 after infection, and prolonging survival times without toxicity. The total numbers of infiltrated cells in the bronchoalveolar lavage fluid (BALF), especially macrophages and neutrophils, were significantly reduced by 06CC2 administration on day 2. On day 2, tumor necrosis factor (TNF)-α production in BALF was also reduced significantly, but interferon-α, interleukin-12, and interferon-γ productions were augmented and natural killer (NK) cell activity was significantly elevated. Furthermore, the gene expressions of interleukin-12 receptor and interferon-γ in Peyer's patches were augmented by 06CC2 administration on day 2. Thus, 06CC2 was suggested to alleviate influenza symptoms in mice in correlation with the augmentation of NK cell activity associated with the enhancement of interferon-α and Th1 cytokine productions through intestinal immunity and the reduction of TNF-α in the early stage of infection.

A dietary supplement improves outcome in an experimental influenza model in old mice.

Twenty-month-old Swiss mice were allocated into three groups: (A) control; (B) infected group; and (C) infected but treated with 5 mg of the phytocompound MMT. Mice were infected intranasally with 30 microL of 75 HA viral units. MMT markedly blunted the nasal signs of virus infection and the febrile response. Formazan-positive cells, lung and plasma lipoperoxides, and TNF-alpha in lung tissue increased during viral infection, but improvement was seen in the MMT-treated group (P < 0.05). MMT also normalized SOD, catalase activities, and ascorbic acid and determined a significant decrease of lung but not nasal viral titer, although nasal inflammatory infiltrate dropped significantly. MMT has potential clinical applications with and has an excellent safety profile even in old animals.

Effect of long-term dietary antioxidant supplementation on influenza virus infection.

This study compared the effect of vitamin E on the course of influenza infection with that of other antioxidants. (In a previous study we showed that short-term vitamin E supplementation significantly decreased pulmonary viral titer in influenza-infected old mice). Eighteen-month-old C57BL/6NCrlBR mice were fed one of the following semisynthetic diets for 6 months: control, vitamin E supplemented, glutathione supplemented, vitamin E and glutathione supplemented, melatonin supplemented, or strawberry extract supplemented. After influenza virus challenge, mice fed vitamin E-supplemented diet had significantly lower pulmonary viral titers compared to those fed the control diet (10(2.6) vs 10(4.0), p < .05) and were able to maintain their body weight after infection (1.8+/-0.9 g weight loss/5 days postinfection in vitamin E group vs 6.8+/-1.4 g weight loss/5 days postinfection in control group, p < .05). Other antioxidants did not have a significant effect on viral titer or weight loss. There was a significant inverse correlation of weight loss with food intake (r = -.96, p < .01), indicating that the observed weight changes were mainly due to decreased food intake. Pulmonary interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF)-alpha levels increased significantly postinfection. The vitamin E group had lower lung IL-6 and TNF-alpha levels following infection compared to the control group. In addition, there was a significant positive correlation between weight loss and lung IL-6 (r = .77, p < .01) and TNF-alpha (r = .68, p < .01) levels. Because IL-6 and TNF-alpha have been shown to contribute to the anorexic effect of infectious agents, the prevention of weight loss by vitamin E might be due to its reduced production of IL-6 and TNF-alpha following infection. Thus, among the antioxidants tested, only vitamin E was effective in reducing pulmonary viral titers and preventing an influenza-mediated decrease in food intake and weight loss. Other dietary antioxidant supplementations that reduced one or more measures of oxidative stress (4-hydroxynonenal, malondialdehyde, and hydrogen peroxide) did not have an effect on viral titer, which suggests that, in addition to its antioxidant activity, other mechanisms might be involved in vitamin E's beneficial effect on lowering viral titer and preventing weight loss.