Oral administration of heat-killed Lactobacillus pentosus strain b240 augments protection against influenza virus infection in mice

Host-defense mechanisms against influenza virus (IFV) infection involve both innate and acquired immunities. Among other components, secretory immunoglobulin A (SIgA) in the airway mucosa plays a particularly pivotal role in preventing IFV infection. Among 150 strains of lactic acid bacteria, Lactobacillus pentosus strain b240 (b240) has the highest IgA-inducing potency in mouse Peyer's patch cells. We previously reported a practical new finding that oral ingestion of nonviable heat-killed b240 elevates salivary IgA secretion in humans. The present study aimed to determine if nonviable b240 can prevent IFV infection in mice. In a BALB/c mouse model infected with lethal levels of IFV A/PR8/34 (H1N1), oral administration of b240 for 3 weeks by gavage prior to IFV infection significantly prolonged the survival period. For IFV infection at nonlethal levels, the infectious titers of IFV in the lungs 7 days after infection were significantly reduced after similar b240 administration. Both anti-IFV IgA and immunoglobulin G titers in bronchoalveolar lavage fluid and plasma on day 7 were significantly higher in the b240-treated group than the control group. The augmentation of the anti-IFV immune response by b240 application was preliminarily confirmed by the elevated production of IFV-driven T-cell factors during mixed lymphocyte reactions with b240-primed splenocytes. These results suggest that oral nonviable heat-killed b240 intake can facilitate protection against IFV infection.     

Intranasal administration of live Lactobacillus species facilitates protection against influenza virus infection in mice

Influenza virus infections continue to be a significant public health problem. For improved therapies and preventive measures against influenza, there has been an increased tendency in modern medicine involving the use of probiotics. In this study, we compared the protective efficacy of various live and dead Lactobacillus species against challenge with influenza virus in mice according to the administration route and dose. In addition, to understand the underlying mechanism behind this clinical protective effect, we performed immunologic assays including examination of IgA levels and cytokine profiles in the lung. The survival rate of mice receiving intranasal administration of Lactobacillus was higher than after oral administration, and administration of live bacteria was more protective than of dead bacteria. The lung levels of interleukin (IL)-12 and IgA were significantly increased (P < 0.05). Conversely, the levels of the pro-inflammatory cytokines tumor necrosis factor-alpha and IL-6 were decreased. Interestingly, there were huge differences in protective effects of various Lactobacillus strains on influenza virus infection. Therefore, for clinical applications, selection of effective strains could be critical and individually optimized application regimens of the selected strains are required.     

Oral administration of Bifidobacterium longum ameliorates influenza virus infection in mice

We investigated whether the oral administration of Bifidobacterium longum BB536 could ameliorate influenza virus (IFV) infection in a mice model. Mice were orally administrated BB536 or saline for 2 weeks and then infected with IFV. Orally administered BB536 significantly alleviated symptoms, reduced the loss of body weight, and inhibited viral proliferation in the lungs relative to the control group findings. Histopathological findings in the lungs were improved in the BB536 group compared to control group findings. There was no significant difference in the levels of interleukin-6 (IL-6), interferon-γ (IFN-γ), IL-10 and IL-12p40 in the lungs between the groups, but the levels of IL-6 and IFN-γ were lower (p=0.076, 0.103, respectively) in the BB536 group compared with those of control group. The levels of IL-6 and IL-10 correlated significantly with the values of weight loss, and the levels of IFN-γ correlated with the virus titers in the lungs. These results suggested the potential of the oral administration of BB536 in ameliorating IFV infection and the possible involvement of anti-inflammatory effects of BB536 in the anti-infection effects against IFV.     

Oral administration of heat-killed Lactobacillus plantarum L-137 enhances protection against influenza virus infection by stimulation of type I interferon production in mice

We have previously reported that heat-killed Lactobacillus plantarum L-137 (HK-LP) stimulates macrophage/dendritic cells to produce T helper (Th) 1-related cytokines in vitro and in vivo in mice. We here examined the effect of oral administration of HK-LP on protection against influenza virus infection in mice. C57BL/6 mice were orally given HK-LP from day − 7 to 7 and intranasally infected with influenza virus A/FM/1/47 (H1N1, a mouse-adapted strain) at 100 pfu on day 0. The survival time was significantly prolonged in mice treated with HK-LP than that in mice treated with PBS as controls. The viral titers in the lung were significantly lower in mice treated with HK-LP than controls at the early stage after influenza virus infection. An appreciable level of interferon (IFN)-β was detected in the serum of mice treated with HK-LP, while no IFN-β was detected in controls after influenza infection. Our results suggest that HK-LP, a potent IFN-β inducer, is useful for prevention against influenza infection.     

百秋李醇对幽门螺杆菌致小鼠胃炎的保护作用

目的: 探讨百秋李醇对幽门螺杆菌(Helicobacter pylori)感染小鼠胃炎的保护作用及其作用机制。方法: 采用化学致癌剂和幽门螺杆菌联合诱导法建立胃炎模型, 将C57BL/6小鼠分为正常组、模型组、阳性对照组(铋剂四联疗法)、百秋李醇高剂量组(40 mg·kg^-1)、百秋李醇低剂量组(20 mg·kg^-1)。灌胃给药, 连续治疗4周后, 行快速尿素酶试验, 评价胃组织中幽门螺杆菌的定植程度; 酶联免疫吸附法测定血清中白细胞介素8(IL-8)和肿瘤坏死因子α(TNF-α)浓度, 免疫组织化学法和实时定量聚合酶链反应法测定胃黏膜Wnt2、β联蛋白(β-catenin)及核因子κB(NF-κB)的蛋白及基因表达。结果: 各给药组小鼠胃黏膜的腺体排列、炎性细胞浸润及不典型增生等病变现象均有显著减轻, 百秋李醇高、低剂量组对幽门螺杆菌根除率分别为78%、70%, 与模型组相比组间差异均有统计学意义(P＜0.01);与模型组相比, 百秋李醇高、低剂量组小鼠血清IL-8和TNF-α水平均有显著降低(P＜0.01);与模型组相比, 百秋李醇高、低剂量组小鼠胃黏膜Wnt2、β-catenin和NF-κB蛋白及基因表达均有显著降低(P＜0.05或P＜0.01)。结论: 百秋李醇可通过抑制NF-κB信号转导通路及Wnt/β-catenin信号转导通路的持续活化及相关炎性细胞因子的高表达, 减轻胃黏膜炎症反应, 防止胃黏膜细胞上皮-间质样转化的发生, 从而阻止或延缓胃肠癌前病变的进程。     

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 (20 mg/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.     

Oral administration of proteoglycan isolated from Phellinus linteus in the prevention and treatment of collagen-induced arthritis in mice

To examine whether oral administration of proteoglycan derived from Phellinus linteus, which is known as the medicinal mushroom, can prevent or treat collagen-induced arthritis (CIA) in mice as experimental model of autoimmune disease. CIA was induced by intradermal injection of type II collagen (CII) emulsified with complete freund's adjuvant (CFA) into the base of the tail (on day 7) followed by a booster injection on day 21 into the footpad. To examine the ability of proteoglycan to effect the inhibition of CIA, doses of proteoglycan were orally administered on day 0 (pre-administration) or day 28 (post-administration) at two groups. The inhibition of CIA by oral administration of proteoglycan was associated with decrease in anti-CII IgG and IgG2a antibodies (Abs) as well as varying kinds of cytokines including IL-12, TNF-alpha, and IFN-gamma. The results showed that administration of proteoglycan was followed by decrease of CIA of the mice in pre- and post-administration groups. Our findings suggest that immunomodulating proteoglycan isolated from P. linteus may be crucially involved in the prevention and treatment of autoimmune joint inflammation such as rheumatoid arthritis, although no definite role of anti-CII Abs in the human disease has been established.     

The protector effect of ribosomal preparations against experimental influenza infection in mice

A study was conducted on the protective effect of some ribosomal preparations, isolated from chorionic-allantoic membranes of chicken embryos, infected or not with parainfluenza (Sendai) or influenza (AoPR8) virus, in mice experimentally inoculated with influenza virus strain AoPR8 adapted to the mouse. Results showed that the tested preparation, containing ribosomes and polysomes isolated from chorio-allantoic membranes of Sendai virus inoculated chicken embryos, ensure the mice complete protection against AoPR8 virus, if administrated before the control infection.     

Polymeric inhibitor of influenza virus attachment protects mice from experimental influenza infection

Synthetic sialic acid-containing macromolecules inhibit influenza virus attachment to target cells and suppress the virus-mediated hemagglutination and neutralize virus infectivity in cell culture. To test the protective effects of attachment inhibitors in vivo, mice were infected with mouse-adapted influenza virus A/Aichi/2/68 (H3N2) and treated with synthetic polyacrylamide-based sialylglycopolymer PAA-YDS bearing moieties of (Neu5Acalpha2-6Galbeta1-4GlcNAcbeta1-2Manalpha1)2-3,6Manbeta1-4GlcNAcbeta1-4GlcNAc. Single intranasal inoculations with PAA-YDS 30 min before or 10 min after infection increased the survival of mice (P<0.01). Multiple treatments with aerosolized PAA-YDS on days 2-5 post infection also increased survival (P<0.01), alleviated disease symptoms, and decreased lesions in the mouse lungs. These data suggest that synthetic polyvalent inhibitors of virus attachment can be used for prevention and treatment of influenza.     

FimH, a TLR4 ligand, induces innate antiviral responses in the lung leading to protection against lethal influenza infection in mice

Fimbriae H protein (FimH) is a novel TLR4 ligand that has been shown to stimulate the innate immune system and elicits protective responses against bacterial and viral infections. Here, we evaluated the protective role of local delivery of FimH against influenza A infection in a mouse model. We show that intranasal delivery of FimH prior to lethal challenge with influenza A virus, resulted in decreased morbidity and mortality in wild-type, but not TLR4^−/−, mice. Importantly, FimH was able to reduce the early viral burden in the lung leading to minimal cell infiltration into the airway lumen and reduced pulmonary pathology following infection in wild type mice compared to TLR4^−/− mice. Local delivery of FimH to C57BL/6, not TLR4^−/−, mice in a prophylactic manner increased the IL-12 and RANTES responses as well as neutrophil recruitment into the airway lumen. These effects correlate to the course of influenza infection. The FimH-mediated antiviral response against influenza virus appears to be partially dependent on alveolar macrophages. The antiviral effects are likely mediated by the innate mediators (TNF-α, IL-12 or RANTES) and/or by activation of a feedback inhibition loop to curtail the pulmonary inflammation possibly be the potential mechanisms involved in FimH-mediated protection. FimH thus holds promise to be a possible prophylactic mean of control against influenza viral infection.     

N-acetylcysteine synergizes with oseltamivir in protecting mice from lethal influenza infection

Many studies have shown that oxidative stress is important in the pathogenesis of pulmonary damage during influenza virus infections. Antioxidant molecules are therefore potentially useful against viral infection. Our previous studies show that N-acetylcysteine (NAC) has a protective effect in a model of lethal influenza infection in mice. NAC administration significantly decreased the mortality in infected mice. Further studies have demonstrated that NAC enhanced survival in combination with the antiviral agent ribavirin. In the present study, we report the effect of combined treatment with NAC and Oseltamivir, clinically used in the treatment and prevention of influenza virus infection, in a murine model of lethal influenza infection. NAC was given as a single daily dose of 1000 mg/kg starting from 4 h before infection and until day 4 after infection; Oseltamivir was given twice daily at dose of 1 mg/kg/die for 5 days, starting from 4 h before infection. End-point evaluation was 21-days survival. NAC alone was slightly effective (20%), since a suboptimal treatment was used. Survival increased to 60% with Oseltamivir and to 100% with Oseltamivir and NAC used in combination. Since NAC alone does not show any antiviral action, the present findings suggest that antioxidant therapy increase survival by an improvement in host defense mechanisms, and/or by a direct antioxidant effect against oxidative stress associated with viral infection. Our studies demonstrate the effectiveness of combining agents acting through different mechanisms, such as antiviral drugs oseltamivir and the antioxidant NAC, indicating a possible advantage of combining the two treatments.     

Protection by methyl inosine monophosphate (MIMP) against aerosol influenza virus infection in mice

Methyl inosine monophosphate (MIMP) is a novel thymomimetic purine immunomodulator capable of enhancing a wide variety of immune responses. Intravenous (i.v.) administration of MIMP 1 day prior to influenza virus infection could confer partial protection and significantly increase the mean survival of treated mice. Intranasal (i.n.) administration of MIMP improved survival rates and incorporation of MIMP in squalane-saline emulsion 1 day prior to or 1 h after influenza infection conferred complete protection. Mice administered MIMP had reduced levels of lung virus and lower titers of circulating serum hemagglutination-inhibition (HI) antibodies. Complete survival and reduction of viral load after influenza challenge infection suggests effective stimulation by MIMP of protective responses against influenza virus.     

Oral administration of L-arginine prevents congestive heart failure in murine viral myocarditis

Naftidrofuryl, a 5-hydroxytryptamine 2 (5-HT 2 ) serotonergic receptor antagonist with vasodilator effects, has successfully been used for intermittent claudication, some forms of dementia, and glaucoma. Recently, an additional mode of action of naftidrofuryl (i.e., mixed endothelin receptor antagonism) has been suggested. However, in the current study naftidrofuryl was unable to block endothelin-3-induced free intracellular calcium increases, in contrast to a mixed endothelin receptor antagonist, bosentan. The inhibition of forskolin-induced renin secretion by endothelin-3 in primary cultures of mouse juxtaglomerular cells and by endothelin-1 in the isolated perfused rat kidney could not be blocked by naftidrofuryl. Naftidrofuryl was unable to block marked endothelin-1-induced renal vasoconstriction in isolated perfused rat kidney. In contrast, naftidrofuryl markedly attenuated serotonin-induced renal vasoconstriction and nearly completely blocked serotonin's renin inhibitory properties in isolated perfused rat kidney. The present results suggest that naftidrofuryl is a potent antagonist of serotonin's renal effects, but has no endothelin receptor-blocking properties.     

Oral administration of exopolysaccharide from Aphanothece halophytica (Chroococcales) significantly inhibits influenza virus (H1N1)-induced pneumonia in mice

The halophilous cyanobacterium Aphanothece halophytica releases large sums of single type sulfated exopolysaccharide in late logarithmic growth phase in culture. This polysaccharide contained sulfate up to 34.46% of the total moieties in the molecular. As a sulfated polysaccharide that can be biosynthesized in large quantities, however, its antiviral activity has not yet been reported. In this study, we examined effects of exopolysaccharide from A. halophytica Fremy (EPAH) on influenza virus A FM (H1N1) (FM1)-induced pneumonia and reduction in immunocompetence in mice. Previous and simultaneous treatment of EPAH at a dose of 60 mg/kg significantly inhibited pneumonia in FM1-infected mice by 30.4% and 26.7%, respectively. In post-treatment, EPAH displayed its most effective inhibition at a dose of 80 mg/kg with the inhibition rate at 18.69%. Simultaneous treatment of FM1-infected mice with EPAH showed effective improvement on reduction of lymphocyte number with its most effective dose at 60 mg/kg. FM1-infected mice simultaneously received EPAH at a dose of 40 mg/kg also acquired obvious enhancement on release of IL-2 on day 15, and those received EPAH at a dose of 60 mg/kg showed similar enhancement on day 10. Simultaneous treatment with EPAH indicated remarkable recovery or improvement of FM1-induced reduction of IL-1beta level and phagocytic capacity of RES. Simultaneous treatment with EPAH significantly resumed the cytolytic activity of natural killer cells in FM1-infected or CP treated mice at doses of 40 and 60 mg/kg. These results suggested that EPAH is an effective agent against FM1. The mechanisms of its action might be mediated, at least in part, by modulating the host immune system and the interaction positive charges in EPAH and negative charges FM1.     

Effects of oral administration of yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 and its exopolysaccharides against influenza virus infection in mice

Yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 (1073R-1) has been shown to reduce the risk of catching cold in the healthy elderly (Makino et al., Br. J. Nutr., 104, 998–1006, 2010). In addition, the exopolysaccharides (EPS) produced by 1073R-1 were also reported to exert immunostimulatory effects in mice such as the augmentation of NK cell activity (Makino et al., J. Dairy Sci., 89, 2873–81, 2006).So, we investigated anti-influenza virus effects of this yogurt and EPS in mice. The yogurt (0.4 ml/day) and EPS (20 μg/day) were orally administered to BALB/c mice for 21 days prior to intranasal infection with influenza virus A/PR/8/34 (H1N1).As a result, the survival periods were prolonged in both yogurt- and EPS-treated groups compared to the water-treated group. Moreover, in these groups, we observed significant decrease of influenza virus titer and significant increase of anti-influenza virus antibodies (IgA, IgG₁) in the bronchoalveolar lavage fluid at 4 days post infection NK cell activity of splenocytes in both groups was also increased significantly. EPS was further fractionated into neutral EPS (NPS) and acidic EPS (APS), and the NPS (20 μg/day) or the APS (20 μg/day) was orally administered to mice for 21 days prior to the intranasal infection. The survival periods were prolonged in APS-treated group, but not in NPS-treated group.Consequently, we concluded that the yogurt fermented with 1073R-1 exerted anti-influenza virus effects in mice by its immunopotentiating activity, and suggested that the APS produced by 1073R-1 was one of active ingredients.