Subcutaneous Administration of the Anti-Tumor Necrosis Factor α, Etanercept, Immediately After Brain Death Significantly Attenuates Kidney Injury in Rats

Introduction and aim
Brain death (BD) induces a systemic “cytokine storm”. Tumor necrosis factor-alpha (TNFα) has been associated with BD-induced kidney injury. The present study aims at testing whether immediate post-BD administration of the anti-TNFα agent, Etanercept, attenuates the renal damage in rats.

Methods
BD was induced under general anesthesia in 9 male 10-week-old Lewis rats by slow inflation of a 3Fr Fogarty balloon catheter in the extradural space. After confirmation of BD, animals were randomly assigned to receive either a subcutaneous injection of Etanercept (ETNCP group; 2.4 mg/kg, n = 6) or 0.9% NaCl (CTL group, n = 3). Six hours after treatment, circulating TNFα levels were quantified using ELISA. Kidneys were harvested for histological evaluation of acute tubular necrosis (ATN). Immunohistochemistry was performed to assess the kidney injury: KIM-1 for proximal tubular injury; CD11b for myeloid cell infiltration; Caspase 3 for apoptosis; and Ki67 for cellular proliferation. IHC quantification was automated using macros in ImageJ.

Results
Circulating TNFα levels were significantly lower in ETNCPT (14.26 [8.36 - 18.49] pg/mL) compared to CTL (32.60 [18.94 - 38.29] pg/mL, p=0.03). The extent of ATN was reduced in the ETNCP group compared to controls (ETNCPT 30.00 [18.75 - 30.00] vs CTL 40.00 [40.00 - 50.00] % of surface, p = 0.01). ETNCPT versus CTL expressions of KIM1 (0.010 [0.006; 0.013] vs 0.141 [0.094; 0.173] % of surface, p = 0.02), CD11b (0.11 [0.10 - 0.16] vs 0.21 [0.19 - 0.28] % of surface, p = 0.04), and Caspase 3 (0.780 [0.316 - 1.147] vs 2.520 [2.450 - 2.680] of positive tubules/glomeruli, p = 0.04) were significantly different. No difference was observed in Ki67 expression between ETNCPT (1.12 [0.87 - 1.51] % of positive cells) and CTL (1.32 [1.13 - 1.52] % of positive cells) groups (p = 0.54).

Conclusion
Etanercept administration immediately after BD significantly attenuates kidney injury in rats, thereby suggesting that targeted anti-TNFα therapy during donor management may improve kidney transplant health.