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
Recently, a major discovery has been uncovered with the collaboration of Brian Lichty and Yonghong Wan from McMaster’s DeGroote School of Medicine. The study can lead to the development of vaccines for viruses like herpes, a common cold or even cancer. This research explains how our immune system detects a viral infection. Licthy have stated: "If the key immune system component identified in these studies is not triggered, then vaccination fails".
The group have focused in studying the cytosolic dna-mediated activation of the transcription factor IRF3 which is a key event in host antiviral responses. The findings have revealed a fundamental regulatory mechanism for the activation of IRF3 in the cytosolic DNA pathway. Nonetheless, the amazing effort by the lead author, Dr. Fuan Wang have revealed a groundbreaking story that impacts everyone who are infected by a virus, receiving a vaccination or fighting cancer
This study was recently published in "Nature Immunology". Further details can be found here.
Dr. Matthew Miller was featured in Part I of the Vice News mini-documentary, “The Pandemic Ticking Time Bomb”. To watch the full video, click here.
Yung Lee, a 2nd year undergraduate student, was recently awarded with the best overall poster presentation at the 29th annual Ontario Biology Day in Toronto. Competing against over 85 students from different universities across Ontario, Yung’s presented his research on examining the effects of female sex hormones on susceptibility to HSV-2 using a novel air-liquid interface culture. Yung’s accomplishment was especially impressive given that he was one of the youngest researchers at the conference. In addition to making his supervisor, Dr. Charu Kaushic, proud, Yung received a certificate and a $250 prize. Congratulations!
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.
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.
MIRC’s own Dr. Zhou Xing was recently featured on CHCH News for his commentary on the increasing incidence of whooping cough. Whooping cough, or pertussis, is a highly contagious disease with symptoms mimicking that of the common cold, in addition to the characteristic cough. According to Professor Xing, the new pertussis vaccine’s effectiveness may less with time, and that may be a reason why there has been an increased number of whooping cough case. He adds, “Receiving the acelluar pertussis vaccine may not trigger as long lasting immunity as the whole cell vaccine”. Vaccination is a priority to maintain herd immunity and protect those at greatest risk – young infants who cannot attain good vaccine protection.
Click here to watch the full interview.
In realization of his lifelong dream, recent MIRC graduate Dr. Victor Ferreira has been selected to compete on ‘Jeopardy!’, the popular, television trivia show. Victor completed his productive PhD in the laboratory of Dr. Charu Kaushic, where he focused on HIV replication in primary genital epithelial cells, and currently works as a medical researcher at the University Health Network in Toronto. Given that the Jeopardy producers recently announced that Canadians are no longer able to apply to be on the television show due to online privacy laws, he could be one of the last Canadians competing! Support Victor on Jeopardy this upcoming Friday (March 11) and watch as he makes MIRC proud.
Our faculty and trainees would like to extend their sincerest congratulations to two freshly minted PhDs from Dr. Charu Kaushic’s lab, Dr. Kristy Roth and Dr. Jessica Kafka. Congratulations are also extended to Dr. Jocelyn Wessels, an incoming post-doctoral fellow who will be joining the Kaushic lab. All three dedicated women celebrated their PhD convocations this past Saturday. Best wishes for a successful future ahead!
The outstanding work of MIRC post-doctoral fellow, Dr. Rodrigo Jiménez-Saiz from Dr. Manel Jordana's Lab, was recently recognized by European Academy of Allergy and Clinical Immunology (EAACI). He was awarded with the 2015 EAACI Mentorship Programme Award. This award promotes ongoing educational and professional opportunities for young scientists and enhancing Junior Members capacity as professionals.
Still debating getting the flu shot? Associate Professor Dawn Bowdish would strongly suggest that you roll up your sleeves, as vaccination now may help to mitigate the onset of chronic disease, such as dementia, decades later.
Featured on CBC’s The National, and on the popular radio show, Metro Morning, Dr. Bowdish discusses the importance of individuals of all ages getting immunized. Numerous studies (e.g. Shah et al., 2013 & Tate et al., 2014) demonstrate that having the flu – or post-influenza pneumonia – can increase one’s chances of developing other inflammatory diseases later in life, such as dementia, cardiovascular disease, or Type II Diabetes. According to the researcher, the flu and pneumonia frequently go hand-in-hand. Often, it is not the influenza that leads to hospitalization, but rather the pneumonia you get after. Upon developing pneumonia, a large inflammatory event is triggered, which elevates your basal level of inflammation. Many of the age-associated chronic diseases, as aforementioned, share this inflammation as their root cause. As such, Dr. Bowdish recommends that people should receive a pneumococcal vaccination, in addition to influenza immunization. "Every year we invest in a vaccination is a year we invest in good health late in life," she says.
Read more on the CBC website or listen to the radio broadcast.