Microbial volatile communication in human organotypic lung models.

We inhale respiratory pathogens continuously, and the subsequent signaling events between host and microbe are complex, ultimately resulting in clearance of the microbe, stable colonization of the host, or active disease. Traditional in vitro methods are ill-equipped to study these critical events in the context of the lung microenvironment. Here we introduce a microscale organotypic model of the human bronchiole for studying pulmonary infection. By leveraging microscale techniques, the model is designed to approximate the structure of the human bronchiole, containing airway, vascular, and extracellular matrix compartments. To complement direct infection of the organotypic bronchiole, we present a clickable extension that facilitates volatile compound communication between microbial populations and the host model. Using Aspergillus fumigatus, a respiratory pathogen, we characterize the inflammatory response of the organotypic bronchiole to infection. Finally, we demonstrate multikingdom, volatile-mediated communication between the organotypic bronchiole and cultures of Aspergillus fumigatus and Pseudomonas aeruginosa.

The WinCF Model - An Inexpensive and Tractable Microcosm of a Mucus Plugged Bronchiole to Study the Microbiology of Lung Infections.

Many chronic airway diseases result in mucus plugging of the airways. Lungs of an individual with cystic fibrosis are an exemplary case where their mucus-plugged bronchioles create a favorable habitat for microbial colonization. Various pathogens thrive in this environment interacting with each other and driving many of the symptoms associated with CF disease. Like any microbial community, the chemical conditions of their habitat have a significant impact on the community structure and dynamics. For example, different microorganisms thrive in differing levels of oxygen or other solute concentrations. This is also true in the CF lung, where oxygen concentrations are believed to drive community physiology and structure. The methods described here are designed to mimic the lung environment and grow pathogens in a manner more similar to that from which they cause disease. Manipulation of the chemical surroundings of these microbes is then used to study how the chemistry of lung infections governs its microbial ecology. The method, called the WinCF system, is based on artificial sputum medium and narrow capillary tubes meant to provide an oxygen gradient similar to that which exists in mucus-plugged bronchioles. Manipulating chemical conditions, such as the media pH of the sputum or antibiotics pressure, allows for visualization of the microbiological differences in those samples using colored indicators, watching for gas or biofilm production, or extracting and sequencing the nucleic acid contents of each sample.

An ex vivo lung model to study bronchioles infected with Pseudomonas aeruginosa biofilms.

A key aim in microbiology is to determine the genetic and phenotypic bases of bacterial virulence, persistence and antimicrobial resistance in chronic biofilm infections. This requires tractable, high-throughput models that reflect the physical and chemical environment encountered in specific infection contexts. Such models will increase the predictive power of microbiological experiments and provide platforms for enhanced testing of novel antibacterial or antivirulence therapies. We present an optimized ex vivo model of cystic fibrosis lung infection: ex vivo culture of pig bronchiolar tissue in artificial cystic fibrosis mucus. We focus on the formation of biofilms by Pseudomonas aeruginosa. We show highly repeatable and specific formation of biofilms that resemble clinical biofilms by a commonly studied laboratory strain and ten cystic fibrosis isolates of this key opportunistic pathogen.

Key aspects of the molecular and cellular basis of inhalational anthrax.

Bacillus anthracis is the etiologic agent of the disease inhalational anthrax, an acute systemic infection initiated by inhaling spores, which if not rapidly detected and treated, results in death. Decades of research have elucidated novel aspects of anthrax pathogenesis but there are many issues left unresolved.

In vivo efficacy of sitafloxacin in a new murine model of non-typeable Haemophilus influenzae pneumonia by sterile intratracheal tube.

A novel murine model of non-typeable Haemophilus influenzae (NTHi) pneumonia was established. A plastic tube was inserted into the trachea 7 days before bacterial inoculation. Numbers of NTHi recovered from the lungs and trachea were determined for 7 days. Histologically, bronchioles and adjacent alveoli in the intubation group were filled with numerous inflammatory cells. The efficacy of sitafloxacin was compared with ciprofloxacin using the new murine pneumonia model. The data suggest that sitafloxacin displays equivalent efficacy to ciprofloxacin against H. influenzae pneumonia. This new murine NTHi pneumonia model appears useful not only for in vivo evaluation of antibiotics but also for analysis of the pathogenesis of H. influenzae pneumonia.