Immunesenescence and inflammaging: A contributory factor in the poor outcome of the geriatric trauma patient

Compared to younger patients, traumatic injury in older patients is associated with increased mortality and a range of adverse outcomes such as higher rates of infectious episodes, longer length of hospital stay and poor functional outcome at follow up. Data emerging from human and murine-based studies suggest age-related changes in immune function, collectively termed immunesenescence, and the chronic sub-clinical systemic inflammatory state of older adults, termed inflammaging, may contribute to these poor outcomes. Here, we review the findings of these studies, whose results demonstrate that the geriatric trauma patient elicits an immune response to injury that is distinct to that of younger adults, being characterised by reduced immune cell activation, impaired function and abnormal haematopoiesis, defects that are accompanied by an altered inflammatory response that fails to return to a homeostatic baseline in the days following injury. Although considerable evidence is accumulating that demonstrates clear and significant age-related differences in the immune and inflammatory response to traumatic injury, our current understanding of the mechanism(s) that underlie these changes is limited. Future studies that provide a mechanistic explanation for the unique immune and inflammatory response of older adults to traumatic injury are therefore essential if we are to determine whether manipulation of the immune system has potential as a future therapeutic strategy by which to improve the outcome of the geriatric trauma patient.