Spatial cytokine distribution following traumatic injury

- Spatial cytokine gradients exist in tissues following traumatic injury.
- IL-6 concentrations decrease as distance from the injury site increases in both muscle and vessel tissue.
- Cytokines represent potential biomarkers that may be used to define the zone of injury.

Temporal changes in cytokine concentrations following traumatic injuries have been extensively studied. Less is known regarding spatial differences in cytokine concentrations following traumatic injury. The primary aim of this study was to determine the spatial relationship between cytokines and the zone of injury (ZOI). Muscle and vessel tissues obtained from rats subjected to an open femoral fracture were analyzed to determine if spatial cytokine gradients exist that could potentially be used as biomarkers of the ZOI. Samples were collected at 4 time points following fracture from 3 distinct locations: at the fracture site, 1-cm away from the fracture, and from the opposite leg. The concentrations of IL-6, IL-1α, IL-1ß, IL-2, GM-CSF, TNF-α, and MIP-1α were quantified in each sample. Temporally and spatially regulated variations in cytokine concentrations were found. IL-6 showed the most promise as a ZOI biomarker with statistically different spatial concentrations that were inversely proportional to the distance from the fracture in both tissues. IL-1ß and IL-2 also showed spatial differences in concentration in both tissues, while GM-CSF, MIP-1α, and TNF-α showed spatial differences in vessel samples. These results demonstrate that spatial cytokine gradients exist following traumatic injury, representing potential biomarkers that may be used to define the ZOI.