Elevated Serum Interleukin-1β Levels in Male, but not Female, Collision Sport Athletes with a Concussion History

It is increasingly reported that a history of concussion may be associated with chronic deleterious consequences. While the pathophysiology that contributes to these consequences is not well understood, neuroinflammation is postulated to be critical. Activation of multi-protein complexes termed inflammasomes, a key component of this inflammatory response, has been reported in more severe TBIs; however, it has not been investigated in milder TBIs, such as concussion. This study investigated serum levels of interleukin (IL)-1 beta and IL-18 (key proteins activated downstream of these inflammasomes) at acute, sub-acute, and chronic time-points post-concussion. We recruited 105 Australian footballers (65 male, 40 female) during the pre-season, then prospectively followed these players for the occurrence of concussion during the season. At baseline, 58 footballers reported a previous concussion history, and 47 reported no previous concussion history. Additionally, 25 players sustained a mid-season concussion and were sampled at 2, 6, and 13 days post-concussion. Serum levels of IL-1 beta and IL-18 were quantified using highly sensitive Simoa HD-X Analyzer assays. At baseline, IL-1 beta levels were higher in male, but not female, footballers with a previous concussion history compared with footballers with no concussion history. There was also a positive correlation between years of collision sport participation and IL-18 levels in males. No evidence was found in males or females to indicate that IL-1 beta or IL-18 levels differed at 2, 6, or 13 days post-concussion. These findings provide novel insights into potential sex-specific physiological consequences of concussion, and suggest that neuroinflammation may be persistent chronically following concussion in male athletes.

Automated summary

This study investigated serum levels of interleukin (IL)-1 beta and IL-18 post-concussion, finding higher IL-1 beta levels in male athletes with a history of concussion. It also discovered a positive correlation between years of collision sport participation and IL-18 levels in males. However, there were no differences in IL-1 beta or IL-18 levels post-concussion between males and females.