Vienna to Dublin: A successful INBIONET secondment focused on investigating Interferon production in response to bacterial infections

Dec ,05 2016

For a number of years, our group at the Max F. Perutz Laboratories in Vienna has been interested in elucidating the roles of interferons and the mechanisms through which they are induced in the context of bacterial infections. Interferons are cytokines, a class of small signalling molecules secreted by immune cells in response to specific stimuli. They affect the behaviour of surrounding cells by instructing them on how to deal with a particular infection type. As their name suggests, interferons have first been identified through their ability to interfere with viral replication by triggering a so-called antiviral state, making cells harder for viruses to infect. As such, interferon therapy is being used extensively in the clinic to treat viral infections such as hepatitis. In addition, it has long been established that interferons also exert strong immunomodulatory activities and are used to successfully control autoimmune disorders such as multiple sclerosis as well as a number of haematological malignancies.

In the case of bacterial infections, the roles of interferons are much less clear and can be either beneficial or detrimental depending on the particular bacterial pathogen and the type of infection. Our group has made significant discoveries, which shed light on the roles of interferons and the mechanisms through which they are triggered using mouse infections models with our favourite bug, Streptoccocus pyogenes. However, as S. pyogenes is a strictly human pathogen, which does not infect mice outside of the laboratory setting, we needed to confer relevance to our findings by verifying them in the context of human infections.

To achieve this, obvious ethical reasons confined us to in vitro experiments using cell lines and immune cells isolated from the blood of generous donors. Moreover, there were a number of technical challenges to overcome. For one, specific receptors and signalling pathways we had identified in the mouse system were either not present or fundamentally different in human cells. While all the evidence in the literature suggested that there exist human analogues to those molecules and pathways, we needed to start from scratch in order to identify them. In addition, whereas the mouse has one most relevant subtype of interferon in the class we were interested in, humans have upward from 12. While all these human subtypes exert the same biological function by binding the same receptor, each is produced deferentially depending on the particular stimulus or cell type. This latter fact made our task even more challenging given that we were clueless as to the best subtype to use as readout in the context of our infection models.

Luckily, my projects were paired within the INBIONET network with those of Jana Musilova in the group of Andrew Bowie at the Trinity Biomedical Sciences Institute in Dublin, Ireland. This was a perfect match as Andrew and his team of virologists were interested in the human viral recognition pathways overlapping with the ones we were investigating in the context of bacteria. As such, they were a significant source of knowhow in terms of interferon signalling in human cells and had a considerable amount of established technical tools with the potential of being very useful to us. Hence, in August of 2014 I set out to Dublin for a 4-month INBIONET secondment tasked with using the resources available to us in the group of Andrew to investigate the induction of interferons in response to S. pyogenes in human immune cells.

As with any academic exchange, there were initially some obstacles. For example, this was the first instance where a bacterial biosafety level 2 pathogen was being used in Andrew’s laboratory. The proper infrastructure in terms of equipment needed to be set up and some paper work had to be submitted and approved in order to obtain permission to commence my work. Once these hurdles were overcome, I implemented our previously established in vitro human infection models and got to work on testing the various interferon readouts available in Andrew’s lab. While Andrew had in his repertoire genetic assays to measure the induction of most human interferon subtypes individually, a cell-based assay, which can indirectly measure the induction of all interferon subtypes at once, was the one we were most interested in. This particular method makes use of genetically modified reporter cells expressing the receptor for interferons. When bound by any of the interferon subtypes this artificially inserted receptor triggers the release of a chemical color reagent that can be used as an indirect measurement of the sum amount of all interferon subtypes being secreted.

In addition to the technical leap forward my stay in Dublin provided to this particular project, I also benefited from very generous scientific input from Andrew and his team. Moreover, given the different scientific landscape of experts and research topics at the Trinity Biomedical Sciences Institute, I had the opportunity to attend talks from a very broad range of disciplines and rub shoulders with prominent scientists such as Luke O’Neill. Conversely, I’m pleased to have contributed some of my own experience and knowhow to the group of Andrew and particularly to Jana, who during my stay there launched her doctoral project focused on investigating the induction of interferons in response to Staphylococcus aureus, a bacterial pathogen closely related to S. pyogenes in terms of pathology. In conclusion, I am very thankful to Andrew, his team and all INBIONET parties involved for making this personally and scientifically rewarding experience possible.

View on the Liffey river on my way to the Bowie laboratory – Despite what they say is typical of Irish weather, I was blessed with an unusual number of beautiful sunny days during the autumn spent in Dublin