Tag Archives: graduate students

Publication: Streptococcus pneumoniae Colonization Disrupts the Microbial Community within the Upper Respiratory Tract of Aging Mice

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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 howNetusha-sm 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

Publication: A naturally occurring transcript variant of MARCO reveals the SRCR domain is critical for function

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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.

‘Inflamm-aging’ by seniors may impact pneumonia susceptibility

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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.

Bowdish Lab attended Queen’s Park Lobby Day with the Ontario Lung Association!

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Bowdish Lab attended Queen’s Park Lobby Day with the Ontario Lung Association!

On Monday November 30th, the last day of Lung Month, members of the Bowdish Lab joined the Ontario Lung Association to lobby for the Lung Health Act at Queen´s Park. PI Dawn Bowdish and four lab members, Andrea Kellner (visiting PhD candidate), Dessi Loukov (PhD candidate), Kyle Novakowski (PhD candidate) and Justin Boyle (undergraduate), advocated for increased funding for lung research through support of Bill 41: The Lung Health Act. It was a great honour to meet the Speaker of the Legislative Assembly of Ontario, David Levac and talk to him about the importance of lung health. This aim was well received and he encouraged the junior researchers to never stop pursuing their scientific goals. Afterwards the team had the opportunity to explore the stunning architecture and history of Queen´s Park, which first opened in 1860. Later the reception afforded the Bowdish lab the privilege to meet MPPs and organizing members of the Lung Association. One exceptional guest and supporter of the Lung Association is Walter Gretzky, who welcomed people warmly and never tired of giving autographs. Especially inspiring was the prospect of meeting people affected by lung diseases as well as people engaged to directly help them as respiratory educators. This emphasized the importance of research performed in the Bowdish Lab and for whom it is done for. In summary, the day highlighted how research and politics can work together to improve the lives of Ontarians and how democracy works in the context of health.

George Habib from the Ontario Lung Association discusses the importance of the Lung Health Act.

George Habib from the Ontario Lung Association discusses the importance of the Lung Health Act.

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Tammy Villeneuve (OLA), Andrea Kellner, Justin Boyle, MPP Dave Levac, Kyle Novakowski, Dessi Loukov and Dr. Dawn Bowdish meet to discuss the Lung Health Act.

Tammy Villeneuve (OLA), Andrea Kellner, Justin Boyle, MPP Dave Levac, Kyle Novakowski, Dessi Loukov and Dr. Dawn Bowdish meet to discuss the Lung Health Act.

Avee Naidoo recognized for her research by the CIHR Institute of Aging.

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As mentioned in an earlier post, Bowdish lab PhD student, Avee Naidoo, won the Fall 2014 CIHR Institute of Aging Anne Martin-Matthews Doctoral Research Prize of Excellence in Research on Aging and is mentioned in the CIHR’s Institute of Aging newsletter!

Avee Naidoo (PhD candidate) wins the Anne Martin-Matthews Doctoral Research Prize of Excellence in Research on Aging!

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Congratulations to Avee Naidoo for winning the Anne Martin-Matthews Doctoral Research Prize of Excellence in Research on Aging! Avee’s work focuses on studying the role of the microenvironment on age and how this affects immune function in the elderly. Her research will help us to understand the mechanisms behind the impaired antibacterial function seen in the elderly, as well as lead to earlier prognosis of individuals at risk of chronic age related diseases.

Avee will be presented her award at this year’s Annual Scientific and Educational Meeting of the Canadian Association on Gerontology in Calgary, Alberta! She will also be a guest judge for the Student Poster Competition at the meeting so bring your A game!

Avee-med

 

The Bowdish lab has a new PhD student! Congrats Avee!

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Avee Naidoo successfully passed her transfer exam today. She now joins the ranks of Fan Fei, Mike Dorrington, Kyle Novakowski, Dessi Loukov, Sara Makaremi, and Pat Schenck as part of the Bowdish lab PhD posse. Well done Avee!

 

Avee-med

Becoming a PhD student in the Bowdish lab is a family affair. Junior lab members sent their favourite stuffie in to wish Avee luck. It must have worked as she aced it!Becoming a PhD student in the Bowdish lab is a family affair. Junior lab members sent their favourite stuffie in to wish Avee luck. It must have worked as she aced it!

...and a little lab humour. We have both skilled scientists (see picture at bottom) and skilled artists (see whiteboard) in our lab.

…and a little lab humour. We have both skilled scientists (see picture at bottom) and skilled artists (see whiteboard) in our lab.

The Bowdish lab attends the 14th Annual Buffalo Immunology Conference.

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This year our lab is taking the Buffalo Immunology Conference by storm!

Nick Yap (MSc candidate with Dr. Brian Golding) was chosen to give a talk “The evolution of the scavenger receptor cysteine-rich domain of the class A scavenger receptor family”. Dessi Loukov (PhD candidate) will be speaking on “MacrophAGING: The effects of chronic inflammation on macrophage anti-microbial immunity” . Dawn will be giving a talk on “The aging microbiome drives age‐associated
inflammation” while many other members of the team give poster presentations.