Grant: Operating Grant

Approximately a third of deaths in the elderly (65 yrs and older) occur due to infectious disease and of these infection, respiratory infections such as pneumonia and influenza are the most common. Indeed approximately 90% of pneumonia deaths in Canada occur in the elderly. Infections like pneumonia often occur after a period of immobility or a hospital stay (e.g. a hip fracture) and are mark the start of a decline in health and independence. Keeping the elderly healthy and infection free would provide them more years of independence and reduce the cost of care. Conventional wisdom states that the elderly are more susceptible to infectious disease because their immune system just "doesn't work" but the data supporting this belief is thin. Indeed, our recent data demonstrate that age-associated immune decline is a very complicated story. For example, when challenged with the bacterium that causes pneumonia specialized white blood cells called macrophages from the elderly mount a very strong pro-inflammatory response but for reasons we don't understand this response does not protect them from infection. Despite having such a strong pro-inflammatory response their macrophages are defective in recognizing, eating (phagocytosing) and killing bacteria. We believe that it is these defects are what predispose them to acquiring infections, especially pneumonia, and that once they acquire an infection these and other immune defects make it very hard for them to clear the bacteria. The aim of this study is to discover how aging alters macrophage responses to bacteria with the long-term goal of discovering how we can improve macrophage function and prevent infections in the elderly.