The Crosstalk Between the Epigenome and Mitochondria as a Novel Therapeutic Target to Counteract Remote Degeneration Induced by Spinal Cord Injury

SCI is a devastating neurological disorder for which there are not yet restorative therapies. Thus, there is a need to explore new therapeutic strategies to treat SCI patients. To this end an appropriate selection and enrolment of suitable participants is crucial for the success of the therapeutic protocol [1,2]. The selection of participants in SCI trials is often based on injury categories (e.g. sensorimotor complete vs incomplete), and neglects biological aspects (e.g. biomarkers released into the CSF and/or blood) that may be amenable to specific therapeutic interventions. On a biomolecular standpoint, it is renown that CNS lacks the ability to sustain a complete regenerative response after damage, which is partially due to the inability of damaged neurons to sustain an epigenetic pro-regenerative response [3].

The background of the present protocol study stands in pre-existing data which showed a crosstalk between the epigenome gene and mitochondria activated upon SCI. In particular, previous experimental studies conducted on mice red nuclei (RN) demonstrated proteome changes at 7 days and 28 days post-SCI. Further pathway analysis pointed out to the epigenetic enzyme KDM5A as the upstream regulator of this phenotype. KDM5A is a H3K4me3 demethylase protein that plays a fundamental role in mitochondria biogenesis and function whose activity is regulated by mitochondrial metabolites [4,5]. Thereby, preliminary data suggest that downregulation of KDM5A activity and increased mitochondrial metabolism are involved in early neuronal response to remote damage. However, its role in brain pathologies such as in SCI remains still unexplored. Since it is well-established that structural and functional damages of mitochondria is an early event that contributed to neuronal cell death, hindering the possibility of axonal regeneration [6], the molecular background of the experimental branch of the present protocol study stands in the investigation of epigenetic regulation by KDM5A and mitochondrial function. The clinical branch of this study protocol aims to investigate if and how targeted proteomic changes following the acute and chronic phase of SCI may play a role in determining the severity of neurologic impairments, as determined with ASIA grading scale system, at the time of patients' presentation and in the conversion of ASIA grade during follow-up. A previous pilot study conducted by Wichmann et al. has shed light on proteomics after SCI enabling a profiling of inflammatory responses after spinal cord injury, timing of proteomics changes involved in inflammatory responses and differences between proteins title in CSF and peripheral blood. On the other hand, authors failed to prove a correlation between inflammatory proteins expression and timing of expression and neurologic status [7]. However, their paper proved that proteome expression variations SCI-induced can be detected into patients' CSF and serum and that biomarkers released into the CSF and/or blood may provide a plethora of information as to the patients' biological response to SCI. These samples may contain a unique fingerprint that can be used by scientists and clinicians to elucidate the mechanisms underlying irreversible central nervous system (CNS) degeneration following SCI. This could allow treatments to target specific molecules which promote CNS degeneration. Within this context the identification of prognostic biomarkers of SCI will help to assign SCI patients to the correct therapeutic treatment that, in association with canonical therapies, may synergistically act to improve functional recovery.

The aim of the present study is to investigate the presence of prognostic markers in SCI patient-derived serum and CSF with respect to a control group of healthy patients.