Aging and estrogen: Modulation of inflammatory responses after injury

Aged subjects have a poor prognosis after traumatic injury and, regardless of the type of injury, they have slower recoveries and suffer more complications than their younger counterparts. The age-dependent responses may be influenced by the hyper-inflammatory state observed in the aged prior to injury, including elevated levels of interleukin-6 (IL-6). physiological levels of estrogen are beneficial to the immune system, due, in part, to the hormone's ability to attenuate aberrant production of pro-inflammatory cytokines. Using two independent injury models, we have found increased mortality and elevated serum levels of IL-6 in aged mice, when compared to young animals (p < 0.05). In parallel Studies, groups of aged mice given estrogen ( 17 beta-estradiol) prior to scald burn, had significantly improved survival (p < 0.05) and lowered serum IL-6 (p < 0.05). Multiple cellular mechanisms may be involved in mediating the beneficial effects of estrogen on inflammatory and immune responses in aged individuals who sustain an injury. These mechanisms are discussed herein. (C) 2006 Elsevier Inc. All rights reserved.