Age-Related Changes in the Immune Response to Bone Injury

The aged immune system becomes consistently biased towards inflammation, existing in a state of constant low-grade unresolved inflammatory signaling. This changes cell behavior for the worse, and is disruptive to processes that require transient inflammation and participation of immune cells, such as regeneration following injury, or clearance of infectious pathogens. Here researchers discuss some of the details relating to the participation of the immune system in regeneration following bone injury. It is interesting to note the sizable differences between sexes, in addition to those introduced by aging. Inflammation is thought to be dysregulated with age leading to impaired bone fracture healing. However, broad analyses of inflammatory processes during homeostatic bone aging and during repair are lacking. Here, we assessed changes in inflammatory cell and cytokine profiles in circulation and in bone tissue to identify age- and sex-dependent differences during homeostasis and repair. During homeostatic aging, male mice demonstrated accumulation of CD4+ helper T cells and CD8+ cytotoxic T cells within bone while both pro-inflammatory "M1" and anti-inflammatory "M2" macrophage numbers decreased. Female mice saw no age-associated changes in immune-cell population in homeostatic bone. Concentrations of IL-1β, IL-9, IFNγ, and CCL3/MIP-1α increased with age in both male and female mice, whereas concentrations of IL-2, TNFα, TNFR1, IL-4, and IL-10 increased only...
Source: Fight Aging! - Category: Research Authors: Tags: Daily News Source Type: blogs