The ability of exogenous interleukin-12 (IL-12) to elicit protective innate immune responses against the extracellular pathogen Streptococcus pneumoniae was tested by infecting BALB/c mice intranasally (i.n.) with S. pneumoniae after i.n. administration of IL-12. It was found that administration of IL-12 resulted in lower bacterial burdens in the infected mice and significantly improved survival rates. All IL-12-treated mice contained higher levels of pulmonary gamma interferon (IFN-␥) after infection and significantly more neutrophils than infected mice not treated with IL-12. IFN-␥ was found to be essential for IL-12-induced resistance and for neutrophil influx into the lungs, and the observed changes correlated with increased levels of the IL-8 homologue keratinocyte-derived chemokine (KC). In addition, in vitro tumor necrosis factor alpha (TNF-␣) production by alveolar macrophages stimulated with heat-killed pneumococci was enhanced by IFN-␥, and TNF-␣ in turn could enhance production of KC by lung cells. Finally, IL-12-induced protection was dependent upon the presence of neutrophils and the KC receptor CXCR2. Taken together, the results indicate that exogenous IL-12 can improve innate defense in the lung against S. pneumoniae by inducing IFN-␥ production, which in turn enhances chemokine expression, and promotes pulmonary neutrophil recruitment into the infected lung. The findings show that IL-12 and IFN-␥ can mediate a protective effect against respiratory infection caused by extracellular bacterial pathogens.Streptococcus pneumoniae is a human pathogen that infects the host mainly through the respiratory tract. Once it crosses natural barriers, it can cause life-threatening diseases, such as pneumonia, bacteremia, and meningitis (10, 11). This grampositive bacterial pathogen remains a leading cause of serious illness among infants, immunocompromised patients, and individuals over 60 years of age (11). The large number of pneumococcal serogroups limits the utility of vaccines, suggesting that alternative approaches that target innate host defense mechanisms may be necessary for optimal protection against this pathogen (10). Elimination of extracellular bacteria from the lung of a naive host is typically thought to be mediated primarily through phagocytosis and intracellular killing by alveolar macrophages and neutrophils recruited to the site of infection (2).The importance of gamma interferon (IFN-␥) and the IFN-␥-inducing cytokine interleukin-12 (IL-12) in phagocyte activation and protection against intracellular pathogens is well accepted, but little is understood about the significance of these cytokines in protection against extracellular microbes (5). Indeed, it has been reported that IL-12 p40 Ϫ/Ϫ BALB/c mice (mice genetically deficient in IL-12 p40 production) and IFN-␥ Ϫ/Ϫ BALB/c mice (mice genetically deficient in IFN-␥ production) are more resistant to pneumococcal infection than wild-type animals are (12, 16). We have now addressed the roles of IL-12 and IFN-␥ in local protection against pulmo...

Based on a lack of severe phenotype in human IgA deficiency syndromes, the role of IgA in controlling respiratory and gastrointestinal (GI) infections has not been clearly defined. C57BL/6 and BALB/c mice lacking IgA (IgA −/− ) were developed and used to address this question. When exposed to a common GI virus, rotavirus, IgA −/− mice exhibited a substantial and significant delay in clearance of the initial infection compared to wild type mice. IgA −/− mice excreted rotavirus in stool up to three weeks after the initial exposure compared to ten days observed in wild type mice. Importantly, IgA −/− mice failed to develop protective immunity against multiple repeat exposures to the virus. All IgA −/− mice excreted virus in the stool upon re-exposure to rotavirus while wild type mice were completely protected against re-infection. These findings clearly indicate a critical role for IgA in the establishment of immunity against a GI viral pathogen.

Infection with antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is one of the primary causes of hospitalizations and deaths. To address this issue, we have designed antimicrobial coatings incorporating carbon nanotube-enzyme conjugates that are highly effective against antibiotic-resistant pathogens. Specifically, we incorporated conjugates of carbon nanotubes with lysostaphin, a cell wall degrading enzyme, into films to impart bactericidal properties against Staphylococcus aureus and Staphylococcus epidermidis. We fabricated and characterized nanocomposites containing different conjugate formulations and enzyme loadings. These enzyme-based composites were highly efficient in killing MRSA (>99% within 2 h) without release of the enzyme into solution. Additionally, these films were reusable and stable under dry storage conditions for a month. Such enzyme-based film formulations may be used to prevent growth of pathogenic and antibiotic-resistant microorganisms on various common surfaces in hospital settings. Polymer and paint films containing such antimicrobial conjugates, in particular, could be advantageous to prevent risk of staphylococcal-specific infection and biofouling.Keywords carbon nanotube; lysostaphin; nanocomposite; antimicrobial film; methicillin-resistant Staphylococcus aureus (MRSA) It is estimated that out of the expected 2 billion people carrying Staphylococcus aureus (S. aureus) worldwide, up to 53 million individuals are infected with methicillin-resistant S. aureus (MRSA).1 Specifically, S. aureus -related diseases such as septicemia and pneumonia are responsible for a large number of hospitalizations (ca. 480,000 in 2005) and deaths (nearly 11,000 in 2005) in the U.S., alone.2 Staphylococcal infection caused by S. aureus and Staphylococcus epidermidis (S. epidermidis) is also a major concern in patients with indwelling devices such as catheters, heart valves, and prostheses.3 While medical and surgical equipment, hospital rooms, and various other objects in hospital settings provide an kaner@rpi.edu, dordick@rpi.edu. Supporting Information Available: Mechanism of Lst-mediated cell wall degradation, bactericidal activity of films against S. epidermidis, bactericidal efficiency of six-times washed films, and SEM characterization of films with different Lst loadings. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public AccessAuthor Manuscript ACS Nano. Author manuscript; available in PMC 2011 July 27.Published in final edited form as: ACS Nano. 2010 July 27; 4(7): 3993-4000. doi:10.1021/nn100932t. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript easily accessible platform for pathogenic bacteria to settle and proliferate, any surface once touched by an infected person serves as a breeding ground for such pathogens.Considering the magnitude of pathogen-related complications and the assistance of various surfaces in growth and spread of these pathogens, significant attention has ...

Saccharomyces cerevisiae adapts to hypoxia by expressing a large group of "anaerobic" genes. Among these, the eight DAN/TIR genes are regulated by the repressors Rox1 and Mot3 and the activator Upc2/Mox4. In attempting to identify factors recruited by the DNA binding repressor Mot3 to enhance repression of the DAN/TIR genes, we found that the histone deacetylase and global repressor complex, Rpd3-Sin3-Sap30, was not required for repression. Strikingly, the complex was instead required for activation. In addition, the histone H3 and H4 amino termini, which are targets of Rpd3, were also required for DAN1 expression. Epistasis tests demonstrated that the Rpd3 complex is not required in the absence of the repressor Mot3. Furthermore, the Rpd3 complex was required for normal function and stable binding of the activator Upc2 at the DAN1 promoter. Moreover, the Swi/Snf chromatin remodeling complex was strongly required for activation of DAN1, and chromatin immunoprecipitation analysis showed an Rpd3-dependent reduction in DAN1 promoter-associated nucleosomes upon induction. Taken together, these data provide evidence that during anaerobiosis, the Rpd3 complex acts at the DAN1 promoter to antagonize the chromatin-mediated repression caused by Mot3 and Rox1 and that chromatin remodeling by Swi/Snf is necessary for normal expression.The Saccharomyces cerevisiae DAN/TIR genes are among a large group of genes that are upregulated during adaptation to anaerobic growth (37,59,65,66). These genes code for cell wall mannoproteins, which play a significant role in cell wall permeability. The kinetics of expression of these genes ranges from 30 minutes to 3 hours following the onset of anaerobiosis (1,59). This suggests that as the cells descend towards anaerobiosis, certain requirements that are necessary for survival in that milieu are incrementally satisfied by specific alterations in gene expression. The importance of the DAN/TIR genes is further underlined by the fact that disruption of some of them, such as TIR1, TIR3, and TIR4, abrogates anaerobic growth (1), indicating that the corresponding proteins play essential functions during anaerobic adaptation. Moreover, it appears that a complex programmed cell wall remodeling occurs during adaptation to anaerobiosis, as shown by the fact that the major aerobic cell wall mannoproteins encoded by CWP1 and CWP2 are replaced by their anaerobic counterparts, encoded by the DAN/TIR genes, under those conditions (1).The precise mechanisms by which the DAN/TIR genes are regulated are still being elucidated. We showed earlier that these genes are regulated by heme, which is synthesized only in the presence of oxygen, and by three DNA binding transcription factors (2, 13, 59). The activator Upc2 acts through a consensus site termed AR1 to induce the expression of these genes in anaerobiosis. Upc2 was also identified as a regulator of the anaerobic sterol transport system (2, 75). It shares extensive homology with Ecm22 and with a Candida albicans protein (CaUpc2) (71). The repressors Ro...

Asthma is believed to be a risk factor for influenza infection, however little experimental evidence exists to directly demonstrate the impact of asthma on susceptibility to influenza infection. Using a mouse model, we now report that asthmatic mice are actually significantly more resistant to a lethal influenza virus challenge. Notably, the observed increased resistance was not attributable to enhanced viral clearance, but instead, was due to reduced lung inflammation. Asthmatic mice exhibited a significantly reduced cytokine storm, as well as reduced total protein levels and cytotoxicity in the airways, indicators of decreased tissue injury. Further, asthmatic mice had significantly increased levels of TGF-β1 and the heightened resistance of asthmatic mice was abrogated in the absence of TGF-β receptor II. We conclude that a transient increase in TGF-β expression following acute asthma can induce protection against influenza-induced immunopathology.

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The results show that induction of antibacterial humoral immunity is only partially effective in protection against secondary bacterial infections that occur following influenza, and suggest that additional therapeutic strategies to overcome defective antibacterial immunity should be explored.

Sepsis is a complex immune disorder that is characterized by systemic hyperinflammation. Alarmins, which are multifunctional endogenous factors, have been implicated in exacerbation of inflammation in many immune disorders including sepsis. Here we show that Galectin-9, a host endogenous β-galactoside binding lectin, functions as an alarmin capable of mediating inflammatory response during sepsis resulting from pulmonary infection with Francisella novicida, a Gram negative bacterial pathogen. Our results show that this galectin is upregulated and is likely released during tissue damage in the lungs of F. novicida infected septic mice. In vitro, purified recombinant galectin-9 exacerbated F. novicida-induced production of the inflammatory mediators by macrophages and neutrophils. Concomitantly, Galectin-9 deficient (Gal-9-/-) mice exhibited improved lung pathology, reduced cell death and reduced leukocyte infiltration, particularly neutrophils, in their lungs. This positively correlated with overall improved survival of F. novicida infected Gal-9-/- mice as compared to their wild-type counterparts. Collectively, these findings suggest that galectin-9 functions as a novel alarmin by augmenting the inflammatory response in sepsis development during pulmonary F. novicida infection.