: Trauma and/or haemorrhagic shock (HS) drive an excessive systemic inflammatory response, which contributes to multiorgan dysfunction (MODS), and is the main cause of death in the late post-injury phase. There is no specific therapy for MODS Bruton’s tyrosine kinase (BTK) is known to play a role in the activation of the NLRP3 inflammasome which is a key component of the innate inflammatory response. However, its role in trauma-haemorrhage is unknown. BTK activity can be blocked by the inhibitors acalabrutinib (irreversible) and fenebrutinib (reversible). We hypothesised that inhibition of the effects of BTK would reduce MODS in two rat models of HS.
Methods: Male Wistar rats were subjected to HS by withdrawal of blood from the carotid (acute model) or femoral (chronic model) artery to maintain mean arterial pressure (MAP) at 35±5mmHg for 90min following anaesthesia with sodium thiopentone (120mg/kg i.p.; acute model) or ketamine-xylazine (ketamine, 100mg/kg; xylazine, 10mg/kg i.m.; chronic model). Resuscitation was initiated by rapid infusion of shed blood plus Ringer’s lactate. Animals received acalabrutinib (3mg/kg), fenebrutinib (3mg/kg) or the vehicle (5% DMSO, 95% Ringer’s lactate). At 4h (acute model) or 24h (chronic model) after resuscitation, organ injury and dysfunction were evaluated by measuring creatinine (renal dysfunction), ALT (liver injury) and LDH (general organ injury). Pulmonary and hepatic myeloperoxidase activity were determined as an indicator of neutrophil infiltration (chronic model). Statistical analysis: One-way ANOVA followed by Bonferroni’s post-hoc test and presented as mean±SEM. *P<0.05 was considered statistically significant.
Results: When compared to sham rats, HS-rats treated with vehicle presented with significant circulatory failure at the end of the resuscitation period, which was improved by either acalabrutinib or fenebrutinib (p<0.05). When compared to sham rats, HS-rats treated with vehicle presented with significant renal dysfunction and liver injury, which was attenuated by either inhibitor (p<0.05). When compared to sham rats, HS-rats treated with vehicle presented with significant increases in both pulmonary and hepatic MPO activity, which were attenuated by acalabrutinib (p<0.05). No significant differences were observed between HS-rats treated with either inhibitor (p>0.05). Administration of either inhibitor to sham rats had no significant effect on any of the measured parameters (p>0.05).
Conclusions: The results point to a role of BTK in the pathophysiology of organ injury/dysfunction and circulatory failure caused by trauma-haemorrhage. Notably, no significant differences were found between the two structurally and mechanistically different inhibitors, suggesting that the observed beneficial effects in experimental trauma-haemorrhage are most likely due to a drug class related effect.
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