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.     

A conserved matrix epitope based DNA vaccine protects mice against influenza A virus challenge

DNA vaccination represents a unique strategy to overcome the limitations of immunization with conventional vaccines which is restricted by the high variability of influenza viruses. We evaluated the protective efficacy of a plasmid DNA (pDNA), encoding an evolutionarily conserved epitope of viral matrix protein, against the influenza A virus infection. It was found that the mice immunized via the intra-muscular route purely elicited cell mediated immune response to the pDNA, with enhanced level of Th1 cytokines viz. IL-12 and IFNγ production in the stimulated splenocyte supernatant. The cytotoxic T lymphocytes in the spleen of immunized mice significantly lysed the virus-infected MDCK cells. A significant decrease in virus replication was also observed in the lungs of immunized mice and 83% of the mice were protected against the lethal challenge of influenza A viruses. These findings suggest that the plasmid DNA expressing a single matrix epitope may serve as a promising vaccine candidate to provide effective immunity in the susceptible (mouse) population.     

Polyfunctional CD8(+) T cells are associated with the vaccination-induced control of a novel recombinant influenza virus expressing an HCV epitope

In hepatitis C virus (HCV) infection, CD8(+) T cell responses have been shown to be important in viral clearance. Examining the efficacy of CD8(+) T cell vaccines against HCV has been limited by the lack of an HCV infectious model in mice and the differences between MHC restriction in humans and mice. Using HLA-A2 transgenic HHD mice, we demonstrate that intranasally delivered Pam2Cys-based lipopeptides containing HLA-A2-restricted HCV epitopes can induce polyfunctional CD8(+) T cell responses in several organs including the liver. To examine the activity of these responses in an infectious context, we developed a recombinant influenza virus that expresses the NS5B(2594-2602) epitope from non-structural protein 5B of hepatitis C virus (PR8-HCV(NS5B)). We showed that mice inoculated with a lipopeptide containing the NS5B epitope had reduced viral loads following challenge with the PR8-HCV(NS5B) virus. This reduction was associated with the induction of NS5B(2594-2602)-specific IFN-γ and TNF-α co-producing CD8(+) T cells. The T cell receptor usage in the NS5B(2594-2602) response was found to exhibit a Vβ8.1/8.2 bias that was characterized by a narrow repertoire and a common CDR3β motif. This work has identified CD8(+) T cell functions induced by lipopeptides that are associated with viral control and demonstrate the potential of lipopeptide-based vaccines as candidates for treatment of HCV infection.     

Immune responses to fungal infections and therapeutic implications

Host responses to fungi result from a coordinate interplay between innate and adaptative immune system. Neutrophils and monocytes are involved in the non specific clearance of yeasts (e.g. Candida albicans and Cryptococcus neoformans), while T helper 1 type responses are protective via release of interferon gamma. By contrast, T helper 2 responses (IL-4 and IL 10 release) correlate with disease exacerbation and pathology. IL-12 production which enhances T helper 1 type responses seem to exert a beneficial role in the course of Candida infection. In particular, its production from neutrophilis may support memory T helper 1 cell responses of the fungus. With respect to anti-Candida vaccines several approaches are in progress, such as use of heat-killed Candida albicans in combination with adjuvants, purified peptides and proteins and immunogenic peptide-lipid conjugates. Furthermore, exogenous IL-12 may play an important role in inducing a T helper 1 anticandidal response, also replacing neutrophils in neutropenic patients. At the same time, granulocyte-colony stimulating factor has exhibited therapeutic efficacy in experimental and human models of fungal infection.     

Proinflammatory and Th1 cytokine alterations following ultraviolet radiation enhancement of disease due to influenza infection in mice.

Exposure of rodents to immunosuppressive agents such as ozone, dioxin, or ultraviolet radiation (UVR) leads to increased morbidity and mortality following influenza virus infection. However, these adverse effects are not related to the suppression of virus-specific immune responses. Our laboratory showed that UVR increased the morbidity, mortality, and pathogenesis of influenza virus without affecting protective immunity to the virus, as measured by resistance to reinfection, suggesting that UVR and other immunosuppressive pollutants such as dioxin and ozone may exacerbate early responses that contribute to the pathogenesis of a primary viral infection. In the present study, we examined the mechanism of UVR-enhanced mortality in the absence of effects on virus-specific immunity and tested the hypothesis that modulation of cytokine levels was associated with increased deaths and body weight loss. BALB/c mice were exposed to 8.2 kJ/m(2) UVR and were infected 3 days later with a sublethal influenza virus infection (LD(40) of mouse-adapted Hong Kong influenza A/68, H(3)N(2)). Influx of inflammatory cells, proinflammatory cytokines, and cytokines produced by T-helper lymphocytes (Th1 and Th2) were measured in lung homogenates (LH) as well as in bronchoalveolar lavage fluid (BAL). UVR preexposure decreased the influenza-induced lymphocytic influx 5 days after infection, but did not alter macrophage and neutrophil influx into the lung, or increase virus titers significantly. Although interferon (IFN)-gamma, total interleukin (IL)-12, IL-6, and TNF-alpha were altered in mice that received UVR exposure prior to infection, no clear association was made that correlated with the UVR-induced increase in body weight loss and mortality due to influenza infection.     

Immunological effects of the orally administered neuraminidase inhibitor oseltamivir in influenza virus-infected and uninfected mice

Oseltamivir (GS4104), the ethyl ester prodrug of the carbocyclic transition state sialic acid analog GS4071, has been reported to be a striking inhibitor of influenza A and B virus infections in mice and ferrets. Multiple studies indicate this material to also be active against the disease in humans, and it has recently been approved for human use. The effect of oral gavage (p.o.) therapy of oseltamivir on various immune factors considered to be of importance in primary influenza virus infection was studied in mice. Both uninfected animals and those infected with influenza A/NWS/33 (H1N1) virus were used. Doses of 100 mg kg(-1) day(-1) were administered twice daily for 5 days beginning 16 h pre-virus exposure. Two hours after end of treatment, the mice were killed and their spleens assayed for cytotoxic T lymphocyte (CTL) and natural killer (NK) cell activity. Subpopulations of splenic T, T-helper, T-cytotoxic and B lymphocytes as well as macrophages were determined using flow cytometry. Similar significant (P<0.01) increases in CTL activity were seen at effector:target cell ratios of 60:1 and 30:1 in the infected mice treated with oseltamivir or with placebo. NK cell activity was greater in the infected mice than in uninfected mice; the levels in all animals were not significantly affected by treatment with oseltamivir. Macrophage, T, T-helper, T-cytotoxic and B lymphocyte populations were similar in both treated and untreated animals. These data indicate treatment with oseltamivir does not adversely affect the primary in vivo cellular immune responses to influenza virus infection assayed in this study. The experiment was repeated to show that treatment with this compound significantly prevented the development of the infection and inhibited virus titers in the lung. Surviving treated mice on day 21 had mean neutralizing antibody titers of 1:208, and withstood rechallenge with the virus at this time, indicating the initial virus-inhibitory effect also did not prevent the animals from developing an adequate humoral immunity to the virus.     

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.     

Antimetastatic effect of an immunomodulatory arabinomannan extracted from Mycobacterium tuberculosis strain Aoyama B,Z-100, through the production of interleukin-12

In this study, the role of interleukin (IL)-12 on the antimetastatic effect of Z-100 was investigated using wild-type C57BL/6 mice or IL-12p40 knockout (IL-12p40 KO) mice inoculated with highly metastatic B16F10 melanoma. When C57BL/6 mice were inoculated with B16F10 melanoma (2x10(5) cells/mouse i.v.), Z-100 (10 mg/kg i.p.) significantly suppressed the pulmonary metastasis of B16F10 melanoma 14 d after tumor inoculation. On the other hand, the antimetastatic effect of Z-100 was not observed in IL-12p40 KO mice inoculated with B16F10 melanoma. These results indicate that IL-12 is essentially required for the appearance of the antimetastatic effect of Z-100. Since helper T (Th) 2 cell responses have been reported to have a role in tumor metastasis, the regulatory effect of Z-100 on the immune balance of Th1/Th2 cell responses was investigated. In both C57BL/6 mice and IL-12p40 KO mice bearing B16F10 melanoma, Th1 cytokine production (IL-2, interferon-gamma) was significantly suppressed as compared with those in normal mice. On the other hand, Th2 cytokine production (IL-4, IL-10) in these mice was increased. The administration of Z-100 (10 mg/kg i.p.) in C57BL/6 mice bearing B16F10 melanoma improved the balance of Th1/Th2 cell responses from the Th2-dominant state to the normal state. However, the improvement of Th1/Th2 cell responses by Z-100 was not observed in IL-12p40 KO mice bearing the same tumors. In addition, Z-100 significantly increased IL-12 production by macrophages in a concentration-dependent manner, while Z-100 significantly decreased IL-10 production by these cells in vitro. These results suggested that up-regulation of IL-12 production and down-regulation of IL-10 production by Z-100 are related to the improvement of Th1/Th2 cell responses from the Th2-dominant state to the normal state, which resulted in suppression of tumor metastasis.     

Prior exposure to acrolein accelerates pulmonary inflammation in influenza A-infected mice

The combustion product acrolein contributes to several smoke-related health disorders, but whether this immunomodulatory toxicant alters pulmonary susceptibility to viruses has received little attention. To study the effects of prior acrolein dosing on the severity of influenza A viral infection, male BALB/c mice received acrolein (1mg/kg) or saline (control) via oropharyngeal aspiration either 4- or 7-days prior to intranasal inoculation with either influenza A/PR/8/34 virus or vehicle. At 0, 2, 4 and 7 days post-inoculation, lung samples were assessed for histological changes while pulmonary inflammation was monitored by estimating immune cell numbers and cytokine levels in bronchoalveolar lavage fluid (BALF). After viral challenge, animals that were exposed to acrolein 4 days previously experienced greater weight loss and exhibited an accelerated inflammatory response at 2 days after viral inoculation. Thus compared to saline-pretreated, virus-challenged controls, BALF recovered from these mice contained higher numbers of macrophages and neutrophils in addition to increased levels of several inflammatory cytokines, including IL-1α, IL-1β, IL-6, TNF, IFN-γ, KC, and MCP-1. The acrolein-induced increase in viral susceptibility was suppressed by the carbonyl scavenger bisulphite. These findings suggest acute acrolein intoxication "primes" the lung to mount an accelerated immune response to inhaled viruses.     

Examining the relationship between impaired host resistance and altered immune function in mice treated with TCDD

Exposure to TCDD suppresses the immune response to numerous antigens, including bacterial and viral pathogens. Although we administer a non-lethal infection with influenza A virus, we often observe significant mortality in TCDD-treated animals. With the goal of identifying which TCDD-induced defects impair host resistance, we conducted a dose response study to examine whether alteration of particular immunological endpoints could be correlated with mortality. C57Bl/6 mice were treated with vehicle control, or 1, 2.5, 5, 7.5 or 10 microg/kg TCDD 1 day prior to intranasal (i.n.) infection with influenza virus. Survival was monitored for 9 days, when remaining mice were sacrificed and multiple endpoints evaluated. Lymphocyte migration to the lung and the production of virus-specific IgG2a, IgG1, and IgG2b antibodies were significantly diminished, even at the lower doses. IgA was enhanced in all groups treated with TCDD. In contrast, T cell expansion in the lymph node, and the production of IFNgamma and IL-12 were relatively resistant to suppression. Treatment with TCDD also enhanced pulmonary neutrophilia in infected mice. These results suggest that decreased antibody production and hyperinflammation may contribute to the death of TCDD-treated mice, and underscore the importance of evaluating numerous endpoints before concluding that a chemical is or is not immunotoxic.     

Sheng Jiang San,traditional multi-herb formulation,exerts anti-influenza effects in vitro and in vivo via neuraminidaseinhibition and immune regulation

OBJECTIVE Sheng Jiang San(SJS), a multi-herb formulation, is used in treating high fever, thirsty and anxiety in ancient China and it is sometimes used to treat seasonal influenza in modern. However, there is no evidencebased investigation and mechanism research to support SJS′s anti-influenza efficacy. This study aims to investigate the anti-influenza effect of SJS and its possible mechanisms. METHODS In this study, we examined the inhibitory effect of SJS against different influenza viruses on Madin-Darby canine kidney cells. Influenza virus infected BALB/c mice were employed as in vivo model to evaluate the efficacy. Mice challenged with A/PR/8/34(H1 N1) were orally administrated SJS 1 g·kg~(-1) daily for seven days and monitored for 14 d. The survival rate, body mass changes, lung index, lung viral load, histopathologic changes and immune-regulation of the mice were measured. The underlying anti-influenza virus mechanisms were studied by a series of biological assays in vitro to determine if hemagglutinin, ribonucleoprotein complex or nerauminidase were targets of SJS. RESULTS SJS exerted a broad spectrum of inhibitory effects on multiple influenza strains in a dose-dependent manner. And IC50 of SJS against A/WSN/33(H1 N1) was lower than 35 mg·L~(-1). SJS also protected50% of mice from influenza virus PR8 infection. The lung index and the lung viral load of SJS treated mice were significantly decrease compared with untreated mice. SJS 2 g·L~(-1) inhibited 80% of neuraminidase enzymatic activity. SJS also up-regulated TNF-α and IFN-α and down-regulated IL-2 of influenza virus induced mice. CONCLUSION SJS is a useful formulation for treating influenza virus infection.     

丙型肝炎疫苗的研究进展与挑战

丙型肝炎病毒(hepatitis C vires,HCV)是具有高度基因变异性的RNA病毒,恢复期患者或黑猩猩再次暴露于不同型(株)病毒时可发生再感染.因此,研发HCV疫苗存在着巨大的挑战.HCV预防性疫苗黑猩猩体内研究证实,诱导并保持针对多个病毒表位的辅助T细胞和细胞毒性T细胞(cytotoxic T-lymphocyte,CTL)的免疫应答,是清除病毒和防止慢性感染的必要环节.多特异性B细胞应答可快速诱导产生交叉中和抗体,这些抗体有助于细胞免疫应答.此文总结候选HCV疫苗在分子病毒学和抗病毒免疫应答中的研究进展,并就疫苗在黑猩猩和HCV感染者的体内试验研究进行综述.     

Analysis of interleukin 12 protein production and mRNA expression in mice exposed topically to chemical allergens

Interleukin (IL) 12 is a heterodimeric cytokine which stimulates IFN-gamma production and promotes the development of type 1 T helper cells and T cytotoxic cells from their respective precursors. We have described previously that contact allergens such as 2,4-dinitrochlorobenzene (DNCB), and respiratory allergens such as trimellitic anhydride (TMA) induce discrete type 1 and type 2 cytokine secretion patterns, respectively, following repeated topical exposure of BALB/c strain mice. Under such conditions, we have now examined production by draining LNC of the inducible subunit of IL-12 (p40) and p40 and p35 subunit mRNA expression. Cultured LNC prepared from mice treated with DNCB secreted significantly more IL-12 p40 protein than did TMA- or vehicle-activated LNC, such differences becoming more pronounced as the duration of culture increased. Maximal levels of mRNA expression of the IL-12 p40 subunit were observed after 6-24 h of culture in all treatment groups and declined thereafter. Somewhat higher levels were induced following exposure to DNCB, these differences only reached statistical significance at 24 h of culture. Expression of this subunit by LNC from all treatment groups declined with time in culture. Levels of IL-12 p35 mRNA expression were comparable in cultured LNC prepared from allergen and vehicle treated mice and remained constant throughout the entire culture period. These data indicate that the divergent T cell cytokine responses seen in response to contact and respiratory allergens are associated with differential production of IL-12 p40 protein in the absence of substantial changes in the expression of mRNA for either subunit.     

清热祛湿法抗流感病毒的实验研究

目的 观察清热祛湿法对流感病毒所致小鼠病毒性肺炎的作用,通过探讨清热祛湿药物的抗流感病毒免疫调节机制,为指导临床辨证治疗流感提供实验依据.方法 （1）观察清热祛湿法体外抗病毒作用及对小鼠流感病毒性肺炎的影响.（2） 用FM1株甲1型流感病毒感染小鼠.制作病毒性肺炎模型,将小鼠随机分为正常组、模型组、蒿芩清胆汤组、病毒唑对照组,分别用单标法流式细胞仪及ELISA法测定四组小鼠外周血T淋巴细胞哑群（（CD3/CD4、CD8）百分比及比值及血清IL-4、IL-18、IFN-γ的含量.结果 清热祛湿法在体外对流感病毒FM1株无明显的抑制作用,但对小鼠流感病毒性肺炎均有抑制作用,与模型对照组比较,差异有显著性意义（P〈0.05）,与病毒唑组比较,差异无显著性意义（P〉005）蒿芩清胆汤对小鼠感染流感病毒FM1后血中的CD3＋CD4＋百分比和CD3＋CD4＋/CD3＋CD8＋比值下降有一定的抑制作用并且能够降低模型小鼠血清TIL-18及IFN-r的值.结论 清热祛湿药物对流感病毒具有抑制作用,但不是直接杀死流感病毒,而是一方面通过调整T细胞亚群的百分率或CD4＋CD4＋/CD4＋CD8＋比值,另一方面通过降低IFN-r、IL-18表达水平,对流感病毒感染引起的细胞免疫功能降低有一定的抑制作用,从而减少异常的细胞免疫反应,调节和加强体液免疫功能,有利于损伤组织的修复.     

Effect of Hochu-ekki-to (TJ-41), a Japanese herbal medicine, on the survival of mice infected with influenza virus

The antiviral effect of Hochu-ekki-to (TJ-41), a Japanese herbal medicine, was investigated using mice infected with influenza virus. TJ-41 was found to increase the survival rate, prolong the mean survival days, suppress viral growth in bronchoalveolar labage fluid (BALF) and inhibit the lung index (lung consolidation) on day 4 after infection in mice infected with influenza, after the agent had been administered orally once daily from day 7 to 2 before infection and from day 0 to 4 after infection. Administration of TJ-41 decreased the BALF concentrations of IL-1alpha, IL-6 and GM-CSF, but not TNF-alpha or interferon-gamma (IFN-gamma), on day 4 after infection. In addition, TJ-41 elevated the level of IFN-alpha in BALF on day 2 after infection. Yet, TJ-41 did not show any inhibitory effect on the growth of influenza virus in vitro. These results suggest that TJ-41 exerts its inhibitory effect on influenza virus infection via enhancement of the host immune responses in this experimental murine system.     

Intranasal Administration of the TLR2 Agonist Pam2Cys Provides Rapid Protection against Influenza in Mice

The protective role played by the innate immune system during early stages of infection suggests that compounds which stimulate innate responses could be used as antimicrobial or antiviral agents. In this study, we demonstrate that the Toll-like receptor-2 agonist Pam2Cys, when administered intranasally, triggers a cascade of inflammatory and innate immune signals, acting as an immunostimulant by attracting neutrophils and macrophages and inducing secretion of IL-2, IL-6, IL-10, IFN-γ, MCP-1 and TNF-α. These changes provide increased resistance against influenza A virus challenge and also reduce the potential for transmission of infection. Pam2Cys treatment also reduced weight loss and lethality associated with virulent influenza virus infection in a Toll-like receptor-2-dependent manner. Treatment did not affect the animals' ability to generate an adaptive immune response, measured by the induction of functional influenza A virus-specific CD8(+) T cells following exposure to virus. Because this compound demonstrates efficacy against distinct strains of influenza, it could be a candidate for development as an agent against influenza and possibly other respiratory pathogens.     

Diesel exhaust enhanced susceptibility to influenza infection is associated with decreased surfactant protein expression

We have previously shown that exposure of respiratory epithelial cells to diesel exhaust (DE) enhances susceptibility to influenza infection and increases the production of interleukin (IL)-6 and interferon (IFN)-beta. The purpose of this study was to confirm and expand upon these in vitro results by assessing the effects of DE exposure on the progression of influenza infection and on development of associated pulmonary immune and inflammatory responses in vivo. BALB/c mice were exposed to air or to DE containing particulate matter at concentrations of 0.5 or 2 mg/m(3) for 4 h/day for 5 days and subsequently instilled with influenza A/Bangkok/1/79 virus. Exposure to 0.5 mg/m(3) (but not the higher 2-mg/m(3) dose) of DE increased susceptibility to influenza infection as demonstrated by a significant increase in hemagglutinin (HA) mRNA levels, a marker of influenza copies, and greater immunohistochemical staining for influenza virus protein in the lung. The enhanced susceptibility to infection observed in mice exposed to 0.5 mg/m(3) of DE was associated with a significant increase in the expression of IL-6, while antiviral lung IFN levels were unaffected. Analysis of the expression and production of surfactant proteins A and D, which are components of the interferon-independent antiviral defenses, showed that these factors were decreased following exposure to 0.5 mg/m(3) of DE but not to the higher 2-mg/m(3) concentration. Taken together, the results demonstrate that exposure to DE enhances the susceptibility to respiratory viral infections by reducing the expression and production of antimicrobial surfactant proteins.     

Protective efficacy of an H1N1 cold-adapted live vaccine against the 2009 pandemic H1N1, seasonal H1N1, and H5N1 influenza viruses in mice

Vaccination is a key strategy for preventing influenza virus infections. Here, we generated a reassortant virus (SC/AAca) containing the hemagglutinin and neuraminidase genes from a 2009 pandemic influenza virus A/Sichuan/1/2009 (H1N1) (SC/09) and six internal genes from the cold-adapted virus A/Ann Arbor/6/60 (H2N2) (AAca). The SC/AAca reassortant induced a sound humoral immune response and complete protection against homologous SC/09 virus challenge in mice after intranasal administration of an at least 10(6) 50% egg infectious dose (EID(50)) of SC/AAca. SC/AAca inoculation also induced significant CD4+ and CD8+ T cell responses and provided solid protection against heterologous H1N1 and H5N1 virus challenge. Our results suggest that this 2009 H1N1 live vaccine will provide protection against both 2009 pandemic and seasonal H1N1 virus infection and might reduce the severity of H5N1 virus infection in humans. The induction of cross-reactive virus-specific T cell responses may be an effective approach to develop universal influenza vaccines.     

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suppresses the humoral and cell-mediated immune responses to influenza A virus without affecting cytolytic activity in the lung.

The immune response to influenza virus is exquisitely sensitive to suppression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); however, the cellular mechanisms underlying the suppressive effects of TCDD are unknown. Mice exposed to TCDD exhibited a dose-responsive increase in mortality following an otherwise non-lethal influenza virus infection. Given that cytotoxic T lymphocytes (CTL) are generally thought to resolve primary infections in the lung, we tested the hypothesis that exposure to TCDD suppresses T-cell responsiveness, leading to decreased CTL in the lung. After infection with influenza virus, naive CD8+ lymphocytes are activated and differentiate in the mediastinal lymph node (MLN). In mice exposed to TCDD and infected with influenza virus, the number of CD8+ MLN cells was reduced 60% compared to vehicle-treated mice. Moreover, MLN cells from TCDD-treated mice failed to develop cytolytic activity, and the production of interleukin (IL)-2 and interferon (IFN)-gamma was suppressed. Exposure to TCDD also altered the production of virus-specific antibodies, decreased the recruitment of CD8+ cells to the lung, reduced the percentage and number of bronchoalveolar lavage cells bearing a CTL phenotype (CD8+CD44hiCD62L(l) degrees ), and suppressed IL-12 levels in the lung. Despite our findings that exposure to TCDD suppressed T cell-dependent functions, the cytolytic activity of lung lavage cells from TCDD and vehicle treated mice was equivalent, and IFN gamma levels in the lungs of mice treated with TCDD were enhanced 10-fold. Thus, while exposure to TCDD suppressed a number of responses associated with the development of adaptive immunity to influenza virus, a direct link between these effects and enhanced susceptibility to influenza remains unclear.     

Oral administration of patchouli alcohol isolated from Pogostemonis Herba augments protection against influenza viral infection in mice

Seasonal influenza A infection results in considerable morbidity and mortality. The limited efficacy of available therapeutic strategies stresses the need for development and study of new molecules against influenza virus (IFV). Patchouli alcohol (PA), the major chemical constituent of Pogostemonis Herba, was previously found to strongly inhibit influenza H1N1 replication in vitro. In the present study, the in vivo anti-IFV effect of PA was investigated. In a mouse model infected with lethal levels of FM1, oral administration of PA (20 mg/kg to 80 mg/kg) for 7 d post IFV infection significantly increased the survival rate and survival time. For IFV infection at nonlethal levels, the quantity of IFV in the lungs 5 d after infection was significantly reduced after PA (20 mg/kg to 80 mg/kg) administration. Anti-IFV IgA, IgM, and IgG titers in serum on day 6 were significantly higher in the PA-treated group than the IFV-control group. Anti-IFV immune response augmentation was further confirmed by the elevated production of CD3+, CD4+, and CD8+ T cell levels in blood. Furthermore, the levels of inflammatory cytokines, including TNF-alpha, IL-10 and IFN-gamma in serum of mice, were regulated. Lung inflammation was reduced significantly after PA administration, and the effect may be mediated, at least in part, by regulating the lung levels of inflammatory cytokines. Thus, oral administration of PA appears to be able to augment protection against IFV infection in mice via enhancement of host immune responses, and attenuation of systemic and pulmonary inflammatory responses.