Congratulations to Kyle on his wedding. A great time was had by all!
Sara is learning how macrophage receptors move through membranes using high resolution microscopy. Her beautiful work was featured in Decembers bulletin. Congratulations Sara!
For the full bulletin, see here.
Fiona Whelan and Ryan Buensuceso, sit down with the IIDR’s Dr. Dawn Bowdish to discuss how and why she chose science as a career.
Hear the podcast here.
Who’s got the strongest lab at McMaster? I do! We’ve had a great run of success at the Bowdish lab with fully all of our students receiving prestigious scholarships! And that’s not to mention our other successes such as our summer scholarship winners (Jason Fan – IIDR), our students who got their degree and moved on to great things (Dr. Fan Fei – manager of Mass Spec facility, Dr. Mike Dorrington – PDF at the NIH), and our PDF, Dr. Chris Verschoor who got a faculty position!
The Bowdish lab has been working with the Ontario Lung Association to encourage politicians to support Bill #41 – The Lung Health Act. You may not be aware that of all the common chronic diseases (e.g. cardiovascular, diabetes), lung disease is the only one that doesn’t have a dedicated action plan. Because of this rates of lung disease are higher then they need to be and many “best practices” for treating or preventing lung disease are not in place, compromising the health of many Ontarians and increasing health care costs. For this reason MPP Kathryn McGarry put forth a private members bill to create a Lung Health Act for Ontario. Bill 41 would entail establishing a Lung Health Advisory Council to make recommendations to the Minister of Health and Long-Term Care on lung health issues; and requiring the Minister to develop and implement an Ontario Lung Health Action Plan respecting research, prevention, diagnosis and treatment of lung disease. In Novemver our lab attended a provincial lobby day where we discussed the importance of this bill with politicians. On June 6th Dawn gave a deputation to the Committee on Social Policy on why this Bill would be of particular importance to older adults.
To see the entire 4 hours of deputations (ouch!) click here.
To read more of the FAQ around the Lung Health Act click here.
To read more about the Ontario Lung Association’s draft Lung Health Action Plan, click here. (Bonus – you can donate to the Lung Association to support this work via that link too!).
Congratulations to Kyle for passing his comprehensive exam and moving from PhD student to PhD candidate! Well done.
Colonization of Streptococcus pneumoniae within the upper respiratory tract (URT) of elderly individuals is a major concern, as it often results in the development of pneumonia, which can be deadly in this population. A study published by MIRC Masters’ student Netusha Thevaranjan, under the supervision of Dr. Dawn Bowdish, examined how aging can change the composition of the respiratory microbial community and consequently, impact bacterial colonization. Using a mouse model of pneumococcal colonization, the study characterized the composition of the URT microbiota in young, middle-aged, and old mice in both the naïve state, and throughout the course of nasopharyngeal colonization with S. pneumoniae. It was shown that the composition of the URT microbiota differs with age, and that colonization with S. pneumoniae in older mice disrupted pre-existing microbial communities.
Furthermore, the study demonstrated that there were several interspecies interactions between S. pneumoniae and resident microbes. In particular,Streptococcus interacted competitively with Staphylococcus and synergistically with Haemophilus. This work provides insight into how aging influences bacterial colonization, and understanding the relationship between these two factors can help create strategies to protect the elderly from age-associated infections and disease. Read More
Macrophages play a critical role in innate immunity by detecting, engulfing and destroying pathogenic bacteria and alerting neighbouring immune cells to join the fight against infection. They have many different receptors on their cell surface that allow them to carry out these important processes. A particular group of receptors called Scavenger Receptors are vital to this response. A recent study published in Immunology and Cell Biology by PhD student Kyle Novakowski from the laboratory of Dr. Dawn Bowdish has uncovered a mechanism by which a specific scavenger receptor contributes to macrophage-specific antibacterial immunity.
Scavenger Receptors are evolutionarily ancient and have evolved to recognize a wide array of pathogens by detecting ligands that are common across many pathogenic organisms. A particularly important Scavenger Receptor is Macrophage Receptor with Collagenous Structure, or MARCO. MARCO has been shown to significantly contribute to the clearance of Streptococcus pneumoniae colonization of the nose and in models of pneumococcal pneumonia. The NSERC-funded study took a unique approach to functionally characterizing how MARCO contributes to innate immunity by studying a naturally-occurring variant of the receptor. The study highlighted the importance of a particular domain of the receptor that is required for macrophages to bind and internalize ligands. The study also showed that the domain is necessary to enhance the pro-inflammatory response to pathogenic Streptococcus pneumoniae and can enhance cellular adhesion; both vital to proper macrophage functions.
To read the article, please click here.
Antibiotic treatment alone may not be sufficient to treat pneumonia in older adults. In fact, it appears as though the inflammation that comes naturally with age increases the risk of developing pneumonia. “It sounds counterintuitive to limit inflammatory responses during a bacterial infection, but clinical observations and our research indicates anti-bacterial strategies need to be tailored to the age of the patient,” said MIRC’s Associate Professor Dawn Bowdish.
Aging is accompanied by a chronic state of low-level inflammation — sometimes called ‘inflamm-aging’ — which is associated with diseases such as cardiovascular disease, dementia and infections, particularly pneumonia. Upon recognition of an infectious agent, an acute inflammatory response is required to fight infection and resolves shortly after. However, in older adults, where systemic inflammation is already elevated, increases in inflammation during infection do not resolve as quickly. Exposure to these high levels of inflammation appears to impair the ability of monocytes and macrophages to fight infection.
Published today in the journal PLoS Pathogens, MIRC graduate Dr. Alicja Puchta & PhD student Avee Naidoo demonstrated that the higher levels of inflammation in the blood of old mice caused the premature egress of inflammatory monocytes into the blood stream, and contributed to greater systemic inflammation. Although small amounts of inflammation are required to fight infection, enhanced production of inflammation in old mice lead to reduced monocyte and macrophage function. Reducing levels of inflammation in the young mice had no effect but reducing levels in the old mice resulted in improved bacterial clearance and survival against S.pneumoniae.
The research follows a 2015 McMaster study that showed that older adults with pneumonia do better when given drugs, such as corticosteroids, to reduce inflammation in addition to antibiotics. “Our study in mice is consistent with clinical studies that recommend using anti-inflammatories as part of treatment to improve older adults’ defence against pneumonia, and that points to the development of better care,” said Bowdish.
To read the PLoS Pathogens article, please click here.