Aging, traumatic injury, and estrogen treatment

Aged subjects are more likely than young to have a poor prognosis after traumatic injury. Regardless of the type of injury, from scald wound to bone fracture, aged have slower recoveries and suffer more complications than their younger counterparts. This age-dependent phenomenon may be influenced by the hyper-inflammatory state observed in the aged referred to as 'inflamm-aging.' Having elevated levels of pro-inflammatory cytokines, including interleukin-6 (IL-6) and tumor necrosis factor α (TNFα), in the circulation prior to injury may predispose the aged population to produce even higher concentrations of these factors after injury. Marked overproduction of pro-inflammatory cytokines leads to immunosuppression. Since many trauma victims do not die of their primary injuries, but rather succumb following infections and/or other complications at later time points, the functional status of the immune system is of paramount importance. Evidence suggests that at physiological levels, estrogen is beneficial to the immune system. This is due, in part, to the hormone's ability to boost immunity and to attenuate aberrant production of pro-inflammatory cytokines, thus serving as a systemic anti-inflammatory agent. In this short review, an examination of the effects of estrogen on inflammatory and immune responses that are critical to survival and recovery following traumatic injury will be discussed.