O’Brien WT, Symons GF, Bain J, Major BP, Costello DM, Sun M, Kimpton JS, Chen Z, Brady RD, Mychasiuk R, O’Brien TJ, Monif M, Shultz SR and McDonald SJ

J Neurotrauma. 2020 Dec 14.

DOI: https://doi.org/10.1089/neu.2020.7479

Abstract

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 multiprotein complexes termed inflammasomes, a key component of this inflammatory response, have been reported in more severe-TBIs; however, it has not been investigated in milder-TBIs such as concussion. This study investigated serum levels of IL-1β 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, and 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-1β and IL-18 were quantified using highly sensitive Simoa HD-X Analyzer assays. At baseline, IL-1β levels were higher in male, but not female, footballers with a previous concussion history compared to 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-1β 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.