Pharmacological inhibition or genetic deletion of a neurotoxin found abundantly at sites of spinal cord injury will neuroprotect and improve outcome.

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Background:Spinal cord injuries or brain injuries disable millions of people each year, and the cost to national economies run into tens of billions of pounds. Therapies which reduce the extent of neural cell death after injury and that improve survivor outcomes are badly needed.Innovation: We have discovered a neurotoxic molecule that is found abundantly at sites of neurotrauma in humans, rats, and mice after it is released by white blood cells (including neutrophils). Per molecule, it is up to 700 times more neurotoxic than glutamate (a molecule which is toxic at high concentrations when released from injured neurons). Pharmaceutical companies have spent hundreds of millions of pounds trying to develop medicines that inhibit toxins like glutamate; given our discovery of this even more potent neurotoxin at sites of neurotrauma, it merits urgent attention and could be a highly valuable target. Surprisingly, this neurotoxin remains essentially unstudied after neurological injury. Excitingly, we have identified a polyclonal antibody which completely blocks this molecule's ability to kill CNS neurons for at least 48 hours in vitro.Aim 1: We wish to develop therapeutic "monoclonal antibodies" that inhibit this neurotoxin. "Monoclonal antibodies" are a class of therapeutic that can be extraordinarily effective at inhibiting defined molecular targets; they are amenable to engineering for specific properties (e.g., size, longevity in the body, safety profile) and already provide health and commercial benefits worldwide. We now seek to develop and evaluate novel monoclonal antibodies that improve survival of human and rodent CNS neurons exposed to this neurotoxin in Petri dishes (Aim 1 and 2) or in vivo (Aim 3). Aim 2: We have also discovered that cerebrospinal fluid obtained by lumbar puncture from humans within 48 hours of spinal cord injury is toxic to rodent CNS neurons cultured in Petri dishes; we now wish to maximise survival of injured human neurons in Petri dishes by applying our new therapeutic antibodies without, or combined with, inhibitors of other toxins (e.g., glutamate and reactive oxygen species). We will analyse any other residual toxic molecule(s) by separating cerebrospinal fluid into component parts (e.g., based on molecular charge or size), for identification using modern biochemical methods, including but not limited to proteomics. Aim 3: We wish to test the idea that injection of these therapeutic monoclonal antibodies by lumbar puncture (into the cerebrospinal fluid) in mice would improve outcome in a clinically relevant model of contusive spinal cord injury when given in a medically feasible time frame. We predict that short-term treatment with the therapeutic monoclonal antibodies will neutralize this neurotoxin, will improve survival of human CNS neurons, and will improve sensorimotor outcomes (e.g., walking) in the long-term. Alternatively, we will evaluate whether lumbar injection of a known human protein inhibitor of this toxin can improve outcome. Aim 4: Finally, we wish to determine whether mice that lack the mouse equivalents of this neurotoxin show better CNS cell survival and improved recovery in the same clinically relevant model of contusive spinal cord injury. This will enable us to confirm the specificity of our therapeutic monoclonal antibodies, and their mechanisms of action, which in turn will help us optimise our therapy for maximum benefit.Clinical importance: These experiments are important because monoclonal antibodies could be given by straightforward lumbar puncture, within hours of injury, to reduce the amount of disability after spinal cord injury, and potentially also after stroke or traumatic brain injury.These experiments will help us take this potential therapy one step closer to clinical trials.