Interleukin 7 Regulates Adaptive Immunity and Promotes Neurorecovery After Moderate to Severe Traumatic Brain Injury 1,2Shick TJ., 1,2Fine D., 1Vaughan LE., 2,3Vagni V., 1,2Russell AL., 2,3Kochanek PM., 1,2,4Wagner AK. 1. Department of Physical Medicine and Rehabilitation, University of Pittsburgh 2. Safar Center for Resuscitation Research, University of Pittsburgh 3. Department of Critical Care Medicine, University of Pittsburgh 4. Center for Neuroscience, University of Pittsburgh

INTRODUCTION In the MWM, CCI mice treated with high dose rhIL-7 had reduced Inflammation Panel platform acquisition latencies and spent more time in the target zone during probe trials compared to CCI vehicle Luminex findings revealed an uncoordinated adaptive immune response in serum after Sham or CCI vehicle injury, and a more coordinated response with rhIL-7 based on correlational analyses

Lymphopenia is a natural reaction to the innate systemic inflammatory response mounted after CNS injury. rhIL-7 Dosages: • Low Dose = 0.5 μg rhIL-7 OBJECTIVES • High Dose = 5 μg rhIL-7

RESULTS Anxiety Future Directions Motor In the EPM, high dose rhIL-7 treatment recovered TBI-induced Since IL-7 is promiscuous, in the future we would like to perform Wire grip testing showed that TBI-impaired motor strength was anxiety post-CCI more correlations between selective cytokine and soluble improved with low dose rhIL-7 treatment but not high dose receptor markers and behavior, and between lymphocyte counts and behavior.

Interleukin 7 (IL-7) is a cytokine central to lymphoproliferation CONCLUSIONS and influences antibody (Ab) production. Our previous findings suggest elevated IgM autoantibodies (AAbs) to the pituitary and/or Moderate to severe TBI causes lymphopenia and behavioral hypothalamus may result in a “protective autoimmune” state that deficits, which can be significantly improved via intermittent improves neurorepair and reduces the risk for neuroendocrine treatment with rhIL-7, possibly through a coordinated adaptive dysfunction in a clinical population with traumatic brain injury (TBI). immune response.

• The objective of this study was to investigate recombinant humanized (rh)IL-7 as a post-acute, rehabilitation-relevant, REFERENCES neuroreparative treatment that works by modifying and 1. Kumar RG, Boles JA, Wagner AK. Chronic Inflammation After Severe Traumatic coordinating the adaptive immune response post-TBI. Brain Injury: Characterization and Associations With Outcome at 6 and 12 Months Postinjury. J Head Trauma Rehabil. June 2014. doi:10.1097/HTR.0000000000000067. • Since rhIL-7 has a role in lymphoproliferative processes that can 2. Barton DJ, Kumar RG, McCullough EH, et al. Persistent Hypogonadotropic support/restore T-cell homeostasis, rhIL-7 may have a neuro- Learning & Memory Hypogonadism in Men After Severe Traumatic Brain Injury: Temporal Hormone Profiles protective effect post-TBI by alleviating lymphopenia and and Outcome Prediction. J Head Trauma Rehabil. September 2015. promoting IgM AAb synthesis that supports CNS repair and While vehicle treatment had no impact on novel zone entries and doi:10.1097/HTR.0000000000000188. improves behavioral outcomes. time in the NOR test, low dose and high dose rhIL-7 treatment 3. Wagner AK, Brett CA, McCullough EH, et al. Persistent hypogonadism influences improved performance with both parameters in CCI mice estradiol synthesis, cognition and outcome in males after severe TBI. Brain Inj. MATERIALS & METHODS 2012;26(10):1226-1242. doi:10.3109/02699052.2012.667594. 4. Riegger T, Conrad S, Schluesener HJ, et al. Immune depression syndrome following Lymphocyte Counts human spinal cord injury (SCI): A pilot study. Neuroscience. 2009;158(3):1194-1199. Abbreviation Key: doi:10.1016/j.neuroscience.2008.08.021. 5. Brait VH, Arumugam TV, Drummond GR, Sobey CG. Importance of T lymphocytes • CCI = Controlled Flow cytometry revealed that reduction of lymphocytes after CCI in brain injury, immunodeficiency, and recovery after cerebral ischemia. J Cereb Blood Cortical Impact were rescued by rhIL-7 treatment Flow Metab. 2012;32(4):598-611. doi:10.1038/jcbfm.2012.6. • VEH = Vehicle 6. Lundstrom W, Highfill S, Walsh STR, et al. Soluble IL7R potentiates IL-7 bioactivity and promotes autoimmunity. Proc Natl Acad Sci. 2013;110(19):E1761-E1770. • NOR = Novel object IL-7 Blood Lymphocytes IL-7 Spleen Lymphocytes doi:10.1073/pnas.1222303110. recognition 7. Schluns KS, Kieper WC, Jameson SC, Lefrançois L. Interleukin-7 mediates the • MWM = Morris water homeostasis of naïve and memory CD8 T cells in vivo. Nat Immunol. 2000;1(5):426- 432. doi:10.1038/80868. maze 8. Ernst B, Lee DS, Chang JM, Sprent J, Surh CD. The peptide ligands mediating • EPM = Elevates Plus positive selection in the thymus control T cell survival and homeostatic proliferation in Maze the periphery. Immunity. 1999;11(2):173-181. 9. Lü H-Z, Xu L, Zou J, et al. Effects of autoimmunity on recovery of function in adult • TZTA = Target zone rats following spinal cord injury. Brain Behav Immun. 2008;22(8):1217-1230. doi:10.1016/j.bbi.2008.06.006. time allocation Lymphocytes (%) Lymphocytes (%) 10. Schwartz M, Kipnis J. Protective autoimmunity: regulation and prospects for Statistical Analysis: vaccination after brain and spinal cord injuries. Trends Mol Med. 2001;7(6):252-258. • Overall group differences were assessed by one-way or two-way repeated measures ANOVAs using Prism ACKNOWLEDGEMENTS • Multiple comparisons were assessed using Fisher’s LSD post-hoc The authors would like to thank Ian Gober, Luke Persin, Anisha multiple comparisons in Prism (*p<0.05, **p<0.01, ***p<0.001, Mandava, Emma Majerske, and Vaish Bandari at the University ****p<0.0001) of Pittsburgh for their extensive help throughout the project. This • Two-group comparisons were assessed using paired t-tests in Prism research is funded by the UPP Foundation and UPMC Rehab (*p<0.05, **p<0.01, ***p<0.001, ****p<0.0001) Institute.