YopP-Expressing Variant of Y. pestis Activates a Potent Innate Immune Response Affording Cross-Protection against Yersiniosis and Tularemia

Plague, initiated by Yersinia pestis infection, is a rapidly progressing disease with a high mortality rate if not quickly treated. The existence of antibiotic-resistant Y. pestis strains emphasizes the need for the development of novel countermeasures against plague. We previously reported the generation of a recombinant Y. pestis strain (Kim53ΔJ+P) that over-expresses Y. enterocolitica YopP. When this strain was administered subcutaneously to mice, it elicited a fast and effective protective immune response in models of bubonic, pneumonic and septicemic plague. In the present study, we further characterized the immune response induced by the Kim53ΔJ+P recombinant strain. Using a panel of mouse strains defective in specific immune functions, we observed the induction of a prompt protective innate immune response that was interferon-γ dependent. Moreover, inoculation of mice with Y. pestis Kim53ΔJ+P elicited a rapid protective response against secondary infection by other bacterial pathogens, including the enteropathogen Y. enterocolitica and the respiratory pathogen Francisella tularensis. Thus, the development of new therapies to enhance the innate immune response may provide an initial critical delay in disease progression following the exposure to highly virulent bacterial pathogens, extending the time window for successful treatment.     

The role of pre-symbiotic auxin signaling in ectendomycorrhiza formation between the desert truffle <Emphasis Type="Italic">Terfezia boudieri</Emphasis> and <Emphasis Type="Italic">Helianthemum sessiliflorum</Emphasis>

The ectendomycorrhizal fungus Terfezia boudieri is known to secrete auxin. While some of the effects of fungal auxin on the plant root system have been described, a comprehensive understanding is still lacking. A dual culture system to study pre mycorrhizal signal exchange revealed previously unrecognized root–fungus interaction mediated by the fungal auxin. The secreted fungal auxin induced negative taproot gravitropism, attenuated taproot growth rate, and inhibited initial host development. Auxin also induced expression of Arabidopsis carriers AUX1 and PIN1, both of which are involved in the gravitropic response. Exogenous application of auxin led to a root phenotype, which fully mimicked that induced by ectomycorrhizal fungi. Co-cultivation of Arabidopsis auxin receptor mutants tir1-1, tir1-1 afb2-3, tir1-1 afb1-3 afb2-3, and tir1-1 afb2-3 afb3-4 with Terfezia confirmed that auxin induces the observed root phenotype. The finding that auxin both induces taproot deviation from the gravity axis and coordinates growth rate is new. We propose a model in which the fungal auxin induces horizontal root development, as well as the coordination of growth rates between partners, along with the known auxin effect on lateral root induction that increases the availability of accessible sites for colonization at the soil plane of fungal spore abundance. Thus, the newly observed responses described here of the root to Terfezia contribute to a successful encounter between symbionts.     

Cognitive Performance during Sustained Wakefulness: A Low Dose of Caffeine Is Equally Effective as Modafinil in Alleviating the Nocturnal Decline

Cognitive performance at night exhibits a substantial drop, typically before dawn. One of the means of dealing with this phenomenon, as well as with the accompanying sleepiness during sustained wakefulness, is the administration of stimulants. The most widely used and well‐documented stimulants are caffeine, amphetamines, and modafinil. Of these, amphetamines are the least recommended, as they may severely affect behavior. Caffeine and modafinil seem to produce relatively milder side effects and usually only at high doses. Previous comparison studies have revealed equal efficacy of both the stimulants in maintaining alertness and performance during sustained wakefulness. However, these studies used relatively high, and thus not completely safe, doses of these drugs (600 mg caffeine and 400 mg modafinil). Therefore, the aim of the present study was to assess the efficacy of a low and medically safe dose of caffeine (200 mg) and modafinil (200 mg) in maintaining cognitive performance during sustained wakefulness. A flight simulation task was chosen for the assessment of the stimulants in a counter‐balanced, within‐subject design under four different conditions: baseline (no drugs), placebo, caffeine (200 mg), and modafinil (200 mg). The equal effectiveness of both drugs in abolishing the nocturnal drop in cognitive performance, as well as of oral temperature and blood pressure, supported the use of low doses of caffeine and modafinil for the maintenance of alertness in healthy subjects during sustained wakefulness.     

Inverse association between Helicobacter pylori and pediatric asthma in a high-prevalence population

Background: Helicobacter pylori‐associated disease has led to aggressive diagnostic and eradication protocols that are partially responsible for the decrease in prevalence of H. pylori carriage. Recent evidence indicates that in low‐prevalence populations, H. pylori may have protective effects on allergic diseases. The aim of this study was to explore the relationship between pediatric asthma and H. pylori infection in a population with high prevalence of H. pylori infection. Materials and Methods: A national referral laboratory was screened for all ¹³C urea breath tests performed in children aged 5–18 years between 2007 and 2008, for patient demographics and physician‐diagnosed asthma. Data concerning asthma‐associated medication usage were extracted from electronic medical records and databases. Data were analyzed using a stepwise logistic regression model. Results: During the study period, 6959 patients underwent urea breath testing (average age 12.4 ± 3.5 years). Of these, 3175/6959 (45.6%) were positive for H. pylori, and 578/6959 (8.3%) had asthma. Rates of asthma in H. pylori‐positive and H. pylori‐negative children were 7.3 and 9.1%, respectively (odds ratio 0.82; 95% confidence interval (CI) 0.69–0.98; p = .032). We also confirmed that male gender, urban residence, and age are associated with childhood asthma. Conclusions: We demonstrate an inverse association between H. pylori and pediatric asthma in a population with a high prevalence of H. pylori.     

Helicobacter pylori and Non-malignant Diseases

In 2007 Helicobacter pylori research continued to deal with some controversies raised in the last decade. The main problems remain unsolved: peptic ulcer disease negative for H. pylori , synergism of H. pylori infection and aspirin and other nonsteroidal anti-inflammatory drugs or cyclooxygenase 2 specific inhibitors, the role of H. pylori eradication in uninvestigated and nonulcer dyspepsia, and the possible protective effect of H. pylori infection against gastroesophageal reflux disease and its complications such as Barrett's esophagus and adenocarcinoma. The incidence and prevalence of peptic ulcer disease as well as ulcer-related mortality are continuing to decline all over the world. The increasing consumption of anti-inflammatory and antisecretory drugs was not found to change the trend over the last period and therefore H. pylori was considered the key factor in causing ulcer-related mortality. Some progress has been achieved in understanding H. pylori -induced immunological processes, and attack mechanisms, as well as specific pathogenesis in uremic and cirrhotic patients. There is still a lot to learn about the bacterium and host factors related to H. pylori infection and its complications.     

A preliminary analysis of hepatitis C virus in pancreatic islet cells

Background

An association between hepatitis C virus (HCV) and type 2 diabetes (T2D) is supported by numerous epidemiologic studies. We hypothesized that HCV could infect human pancreatic islet cells in vitro.

Methods

Measures of HCV RNA synthesis and protein production were used to evaluate HCV infection of pancreatic islets recovered from human donors.

Results

Significant co-staining of insulin and the HCV entry factor CD81 was observed in pancreatic islets. Positive- and negative-sense HCV RNA were detected in HCV-exposed islets at days 1, 3, 7, and 14 post-infection. The HCV core and NS3 proteins were expressed and increased with time providing further evidence of viral replication. Interferon and an HCV polymerase inhibitor reduced viral replication in islet cells. In HCV-infected islets, TNFα levels were elevated at days 1, 3, and 7 post-infection, while IL-6 levels were elevated at day 1 but not days 3 or 7. Overall, the expression of miR-122 was low in islets compared to the Huh7.5 hepatocyte-derived cell line, although the relative expression of miR-122 increased in islet cells after viral infection (1, 6.63, and 5.83 at days 1, 3, and 7, respectively).

Conclusions

In this pilot study, viral infection was demonstrated in pancreatic islet cells from multiple donors using complementary measures of viral replication, thus providing evidence of in vitro infection. Altered cytokine expression may contribute to the development of insulin deficiency, and understanding the etiology of diabetes in individuals with HCV infection may facilitate the development of novel treatment modalities and prevention strategies. This in vitro system provides an important model for mechanistic studies of HCV-pancreas interactions and facilitates future studies of the potential impact of viral infection on islet cell function.

     

Morphological analysis of young and old pellicles of Salmonella Typhimurium

A wide variety of microorganisms are able to form biofilms at the interface between air and liquid (pellicles). In this study changes during the maturation of the pellicle of Salmonella Typhimurium were analysed and the role of cellulose in the pellicle structure and morphology evaluated. The morphology of both sides of the pellicle was characterised using atomic force microscopy and scanning electron microscopy. Overall, there was a marked difference in the morphology of the water-facing (WF) and air-facing (AF) biofilm surfaces. While the AF side appeared to be uniform, and extensively covered with an exocellular coating, cells in the WF side were distributed into clusters and were less covered. However, the similarity in size and shape of single cells from both sides of the pellicle may indicate that the bacterial cells across the pellicle have a similar physiological status. During maturation, porous structures with multiple cracks and channels were created in the pellicle, leading to disintegration. By comparison with the structure of pellicles of a cellulose-deficient mutant, it was demonstrated that the observed disintegration of mature pellicles probably occurred in part by self-hydrolysis of components of the matrix.