Recombinant T cell receptor ligands improve outcome after experimental cerebral ischemia

Abstract

A key target for novel stroke therapy is the regulation of post-ischemic inflammatory mechanisms. Recent evidence emphasizes the role of T lymphocytes of differing subtypes in the evolution is ischemic brain damage. We have recently demonstrated the benefit of myelin antigen-specific immunodulatory agents known as recombinant T cell receptor ligands (RTLs) in a standard murine model of focal stroke. The aim of the current study was to extend this initial observation to RTL treatment in a therapeutically relevant timing after middle cerebral artery occlusion (MCAO) and verify functional benefit to complement histological outcome measures. We observed that the administration of mouse-specific RTL551 reduced infarct size and improved sensorimotor outcome when administered within a 3 h post-ischemic therapeutic window. RTL551 treatment reduced cortical, caudate putamen, and total infarct volume as compared to vehicle-treated mice. Using a standard behavioral testing repertoire, we observed that RTL551 reduced sensorimotor impairment 3 days after MCAO. Humanized RTL1000 (HLA-DR2 moiety linked to hMOG-35-55 peptide) also reduced infarct size in HLA-DR2 transgenic mice. These data indicate that this neuroantigen-specific immunomodulatory agent reduces damage when administered in a therapeutically relevant reperfusion timeframe.

Fig. 1

RTL551 treatment 4 h after the onset of ischemia reduces infarct volume in C57Bl/6 mice. Representative TTC-stained brains from vehicle- (a) and RTL551-treated (b) mice. Sixty-minute transient MCAO was followed by four daily treatments with vehicle (Tris-HCl) or 100 µg RTL, and the infarction volume was quantified as a percentage of the non-ischemic contralateral hemisphere. (c) Quantification of infarct volume of vehicle- and RTL551-treated mice. Group sizes were n=9 for vehicle and n=11 for RTL551. Data are presented as mean±SEM of individual mice. *Different than vehicle, P<0.05

Fig. 2

RTL551 treatment improved functional recovery after MCAO-affected paw use in vehicle- (Tris-HCl) or RTL551-treated mice were tested 1 day before MCAO (pre), 3 days after MCAO (day 3) and 7 days after MCAO (day 7). Group sizes were n=18 and n=12 for vehicle-treated MCAO and sham mice, respectively, and n=17 and n=13 for RTL551-treated MCAO and sham mice. Data are presented as mean±SEM of individual mice. *Different than vehicle, P<0.05

Fig. 3

RTL1000 treatment 4 h after the onset of ischemia reduces infarct volume in DR2 transgenic mice. Sixty-minute transient MCAO was followed by four daily treatments with vehicle (Tris-HCl) or 100 µg RTL, and infarction volume was quantified as a percentage of the non-ischemic contralateral hemisphere. Quantification of infarct volume of vehicle- and RTL551-treated mice. Group sizes were n=10 for vehicle and n=10 for RTL1000. Data are presented as mean±SEM of individual mice. *Different than vehicle, P<0.05