Investigation of the Relationship Between Calpain and HMGB1/TLR4/NF-KB Signalling Pathway in Multiple Sclerosis and Other Demyelinating Diseases

Background To develop more effective treatments for demyelinating diseases, it is essential to identify the associated signaling pathways and factors. The objective of this study was to investigate the possible correlation between Calpain-1 (CAPN1) and Calpain-2 (CAPN2) with the HMGB1/TLR4/NF-κB signaling pathway and to evaluate the influence of these proteins on Interleukin 17A (IL-17A) and Interleukin 37 (IL-37) cytokines in individuals with newly diagnosed and untreated Multiple Sclerosis (MS) and Neuromyelitis Optica Spectrum Disorder (NMOSD). Methods In this pilot study, a total of 73 newly diagnosed patients were recruited, including 36 with MS, 9 with NMOSD, and an unhealthy control group composed of 28 individuals with Pseudotumour cerebri (PTC). To ensure accuracy and transparency, all groups’ demographic and clinical characteristics were meticulously described. ELISA technique was utilized to compare levels of CAPN1, CAPN2, HMGB1, TLR4, and NF-KB, as well as IL-17A and IL-37 cytokines, between the case and the unhealthy control groups. The expectation from these findings is to provide valuable insights into the pathophysiological mechanisms of these neurological disorders, possibly opening the door to novel therapeutic perspectives. Results In patients with MS, the levels of CAPN1 were found to be higher than those in patients with NMOSD and PTC. Similarly, the level of CAPN2 was significantly higher in patients with MS than in patients with NMOSD and higher in patients with PTC than in patients with NMOSD. There were no differences in the levels of HMGB1, TLR4, NF-κB, IL-17A, and IL-37 between the groups. Age and gender did not affect any of the parameters. In the MS group, both CAPN1 and CAPN2 showed positive correlation with HMGB1, TLR4, and NF-κB levels. Conclusions It may be suggested that CAPN1 may exhibit greater efficacy than CAPN2 during the initial stages of neuroinflammation. To obtain deeper and more guiding results of the varying levels of CAPN1 and CAPN2, and their relationship with the HMGB1/TLR4/NF-κB signaling pathway, it is advisable to conduct in-vivo and in-vitro prospective studies featuring CAPN1-specific inhibitors with larger study groups. ### Competing Interest Statement The authors have declared no competing interest.