Glucocorticoid-Induced Leucine Zipper (GILZ) Over-Expression in T Lymphocytes Inhibits Inflammation and Tissue Damage in Spinal Cord Injury

Spinal cord injury (SCI) is a traumatic event that causes a secondary and extended inflammation characterized by infiltration of immune cells, including T lymphocytes, release of pro-inflammatory mediators in the lesion site, and tissue degeneration. Current therapeutic approaches for SCI are limited to glucocorticoids (GC) due to their potent anti-inflammatory activity. GC efficacy resides, in part, in the capability to inhibit NF-kappa B, T lymphocyte activation, and the consequent cytokine production. In this study, we performed experiments aimed to test the susceptibility of glucocorticoid-induced leucine zipper (GILZ) transgenic (GILZ(TG)) mice, in which GILZ is selectively over-expressed in T lymphocytes, to SCI induction. Consistent with a decreased inflammatory response, GILZ(TG) were less susceptible to SCI as compared to wild-type littermates. Notably, inhibition of NF-kappa B activation and nuclear translocation, diminished T lymphocytes activation and tissue infiltration, as well as decreased release of cytokines were evident in GILZ(TG) as compared to wild-type mice. Moreover, GILZ(TG) showed a reduced tumor necrosis factor-alpha, IL-1 beta, Inductible nitric oxide synthase (iNOS) and nytrotyrosine production, apoptosis, and neuronal tissue damage. Together these results indicate that GILZ mimics the anti-inflammatory effect of GC and represents a potential pharmacological target for modulation of T lymphocyte-mediated immune response in inflammatory disorders, such as SCI.