(1606) GJA1-20K Reduces Levels of Interleukin-6 in Patients With REBOA-Induced Ischemia-Reperfusion Injury

Introduction: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a valuable resuscitation tool for noncompressible torso hemorrhage. REBOA preserves perfusion to the heart and brain while interrupting severe blood loss. However, patients often suffer ischemia-reperfusion injury after REBOA. We previously found that treatment with GJA1-20k, a stress response protein upregulated during ischemia that protects mitochondrial function, reduced serum concentration of interleukin-6 (IL-6). IL-6 concentration correlates with tissue injury severity and predicts mortality. This study investigated whether GJA1-20k reduced IL-6 expression in the renal medulla and liver. We hypothesized that GJA1-20k treatment would be associated with lower renal medullary and hepatic IL-6 expression.

Methods: Twelve anesthetized pigs underwent a splenectomy and 25% of their estimated blood volume was hemorrhaged, followed by 45 minutes of complete supra-coeliac aortic occlusion via REBOA. Twenty-five minutes into the occlusion period, animals received a 1-hr intravenous infusion of 0.9% saline (placebo) or GJA1-20k (0.01 mg/kg). Subsequently, autologous blood was transfused and REBOA was removed. Pigs received critical care and algorithmic resuscitation with isotonic crystalloids and norepinephrine to maintain normotension. Renal medulla and liver samples were obtained following the procedure. The relative mRNA and protein IL-6 expression were quantified by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC), respectively.

Results: RT-qPCR and IHC analyses revealed no difference in liver expression of IL-6 between groups. RT-qPCR analysis revealed lower levels of renal medullary expression of IL-6 in the treated group (Control: 0.51 [0.33-0.69]; GJA1-20k: 0.16 [0.12-0.3] IL-6 mRNA fold change) (p=0.0140). IHC showed lower fluorescence intensity in the renal medulla of animals in the treated group (Control: 126.76 [114.57-150.693]; GJA1-20k: 96.61 [94.14-121.95] mean fluorescence) (p=0.0262).

Conclusions: Animals treated with GJA1-20k had lower levels of IL-6 production in the renal medulla but not the liver. Further studies are needed to understand whether GJA1-20k reduces inflammation, thus decreasing IL-6 production, or if GJA1-20k directly inhibits IL-6 production.