Elastin-like polypeptide delivery of an NF-κB inhibitory peptide for treatment of juvenile mild TBI complicated by high-fat diet consumption

Traumatic brain injury (TBI) involves a primary, force-induced injury to the brain followed by a prolonged and treatment-resistant period of secondary injury. Secondary injury involves adverse neuroinflammation, blood-brain barrier dysfunction, and cell death. Juveniles are at increased risk for mild TBI (mTBI) due to participation in recreational sports, exposure to parental abuse, and vulnerabilities of the developing skull to external damage. Compounding on this increased TBI risk, juveniles frequently consume a diet high in saturated fats and refined sugars, which constitutes a preexisting challenge to brain health prior to the onset of a mTBI. Nuclear factor kappa B (NF-κB) is a transcription factor that regulates numerous proinflammatory genes. NF-κB activity has been implicated in adverse inflammatory states when upregulated following TBI. Inhibition of NF-κB is a promising therapeutic strategy for TBI, as it will induce the downregulation of multiple inflammatory factors, each associated with worse TBI outcomes. We developed a polypeptide biologic, SynB1-ELP-p50i, consisting of an elastin-like polypeptide (ELP) delivered inhibitor of NF-κB (p50i) and the cell-penetrating peptide SynB1. ELPs are non-immunogenic polypeptides derived from human tropoelastin that can stabilize small peptides in circulation and assist with localization of peptide therapeutics. The goal of the current study was to examine the biodistribution, pharmacokinetics, and therapeutic efficacy of SynB1-ELP-p50i in juvenile rats consuming a normal or high-fat (HF) diet exposed to mTBI. Mitigation of the effects of mTBI was assessed behaviorally and with RT-qPCR analysis of inflammatory factors (including markers of gliosis) post-TBI. For the biodistribution and pharmacokinetic experiments, male Long Evans rats were assigned to either chow (CH) or HF diet groups at post-natal day 20 (PND20) and a sham injury or mTBI was induced at PND30 using the closed-head impact model of engineered rotational acceleration device. Ninety minutes following injury, subjects were given 50 mg/kg of rhodamine-labeled SynB1-ELP-p50i. Increased SynB1-ELP-p50i concentration was detected in mTBI versus sham subjects ( t (12) = 2.301, p = 0.04). To assess the therapeutic efficacy of SynB1-ELP-p50i, a separate group of CH and HF diet subjects were treated with SynB1-ELP-p50i or vehicle following a mTBI. Cognitive assessments were performed using the Morris water maze (MWM) 3- and 24-hours post-injury. Relative to sham subjects, TBI subjects performed poorly in the MWM probe test 3 hours post-injury ( p < 0.0001). Likewise, TBI subjects performed worse in the MWM platform-switching task, a test of spatial learning, 24 hours post-injury ( p < 0.05). Effects of injury (but not treatment) on GFAP mRNA expression was detected 3 days post-TBI with RT-qPCR ( p < 0.05). NF-κB inhibition is a viable therapeutic strategy for mTBI, and studies are ongoing to further assess the efficacy of SynB1-ELP-p50i as a treatment to reduce or inhibit secondary injury in juvenile mTBI patients. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.