Project 1

The interaction of bacteria with MUC5AC

In collaboration with Dr. Colm Reid, UCD School of Veterinary Medicine we have developed a system that provides full length recombinant versions of the mucins MUC5AC and MUC2. MUC5AC is expressed in the gastric mucosa and the respiratory tract of humans whereas MUC2 is expressed in the intestinal tract. Using the MUC5Ac constructs expressed in gastric and respiratory cell lines we are now characterising the role of MUC5AC in bacterial binding and identification of parts of the molecule that are relevant to this process. The constructs (which provide a source of purified homogenous, and non-denatured, MUC5AC) allows us to analyse the complexity of the interaction between MUC5AC and P. aeruginosa and MUC5AC and H. pylori at the level of both peptide sequence and glycosylation phenotype.

Project 2

Biomodulation of the gastrointestinal epithelial glycome by bacteria.

We are part of the Alimentary Glycoscience Research Cluster an SFI funded strategic research cluster lead by NUI Galway. In this project we aim to investigate the effect of bacterial colonization by both commensals and pathogens on glycosylation in the gut and how these changes can be either beneficial or harmful to the host. As part of this project we are also looking at the direct interaction of bacteria with oligosaccharides found on mucins and epithelial cell membranes and the role these interactions play in mediating infection. 

Project 3

Elucidation of the mechanisms that Helicobacter pylori uses to modulate TFF1 expression in the gastric mucosa.

We have identified TFF1, a member of the trefoil peptide family of proteins as a factor found in gastric mucus, as a protein that interacts with H. pylori. This interaction which is mediated by the LPS of the bacteria plays an important role in mediating colonization of mucus and gastric cells by the bacteria. Recent work in the laboratory has shown that TFF1 mRNA expression is significantly down regulated upon H. pylori infection of a mucus secreting cell line. Infection of humans has also been associated with decreased TFF1 expression. Depletion of binding molecules in gastric mucus could confer an advantage on the organism, enabling it to reach the underlying epithelium and access nutrients thus promoting disease and chronic infection. TFF1 is important for maintaining the integrity of gastric mucus, it plays a role in wound healing and also acts as a tumour suppressor. We hypothesise that H. pylori modulates TFF1 expression during infection to promote bacterial colonization, persistence and development of disease. In a project funded by IRCSET we aim to elucidate how H. pylori regulates TFF1 expression.

Project 4

The role of mucus and mucins in mediating Pseudomonas aeruginosa colonization of the cystic fibrosis lung.

We have recently obtained funding from the Cystic Fibrosis Association of Ireland and the Health Research Board for this project. Pseudomonas aeruginosa is the bacteria most commonly associated with chronic airway infection in CF patients which leads to a decline in lung function and causes severe problems for CF sufferers. The reasons for the particular predilection of P. aeruginosa for the CF airway, and the very significant negative clinical implications of colonisation are incompletely understood. The prevention of chronic P. aeruginosa infection is a cornerstone of clinical care in CF. In this study we hypothesise that the environment of the CF lung, which contains thick stagnant mucus and mucins with altered glycans compared to non diseased individuals, and is hypoxic and even anaerobic in places plays an important role in initiation of colonisation and maintenance of chronic bacterial infection. We aim to test this hypothesis with a variety of CF and non CF mucus secreting cell lines under different environmental conditions. We will look directly at the role of this mucin in mediating colonization and any secondary pathogen mediated effects on MUC5AC. We will look at the direct interaction of P. aeruginosa with crude mucus and purified mucin including recombinant MUC5AC and the effect of hypoxia and anaerobiosis on any interaction. This will allow for elucidation of the role of mucins in mediating infection. All of the above work will be validated using primary culture of bronchial epithelial cells isolated from bronchial brushings obtained from children with CF. Primary cells are a powerful tool for the study of bacterial pathogens which display a specific tropism for those cells in vivo. This work will be done in collaboration with Scientists and Clinicans from Our Lady's Children's Hospital in Crumlin This work will serve as a valuable reference system for the study of pathogens that colonise and infect the complex mucosal environment in the CF lung and could lead to the development of novel therapeutics aimed at prevention of initial bacterial colonization of mucus in the CF lung.