Spinal Cord Motor Neuron Phenotypes and Polygenic Risk Scores in Sporadic Amyotrophic Lateral Sclerosis: Deciphering the Disease Pathology and Therapeutic Potential of Ropinirole Hydrochloride

This study investigated the genetic factors associated with the onset of amyotrophic lateral sclerosis (ALS) and the mechanism of action of Ropinirole hydrochloride (ROPI) in ALS treatment. Firstly, ALS is a neurodegenerative disease characterized by the degeneration of both upper and lower motor neurons (MNs), and identifying the genetic factors of sporadic ALS (SALS) has been challenging. However, ALS-like phenotypes have been observed in induced pluripotent stem cell-derived lower MNs (iPSC-LMNs) of SALS patients, suggesting a polygenic contribution to SALS pathogenesis, and ROPI has emerged as a novel therapeutic candidate for ALS treatment. Moreover, recent genome-wide association studies (GWAS) have suggested an association between high levels of blood total cholesterol (bTC) and ALS. The study aimed to combine iPSC-LMN phenotypes and polygenic risk scores (PRS) to quantify the genetic background of patients and analyze the mechanism of action of ROPI in ALS treatment. Twenty SALS patients were included in the study, and iPSC-LMN phenotypes, PRS for 58 quantitative traits, and ALS were calculated. The results indicated that patients with a higher PRS for bTC showed changes in iPSC-LMN phenotypes, particularly a higher response to ROPI. Additionally, a correlation was observed between bTC levels and the expression of cholesterol biosynthesis (CB) enzymes in MNs, suggesting their involvement in the pathogenesis of SALS. Furthermore, the study compared the liver and spinal cord expression of CB enzymes and found a correlation between bTC levels and CB enzyme expression, particularly in MNs, which may partly explain the MN-specific pathogenesis of SALS. In conclusion, the study suggests that high bTC levels and increased CB activity may contribute to the pathogenesis of SALS, and CB suppression may be a potential therapeutic strategy for ALS, supported by the mechanism of action of ROPI in ALS treatment. ### Competing Interest Statement Hideyuki Okano reports grants and personal fees as a Chief Scientific Officer from K Pharma, Inc. during the conduct of the study; personal fees from Sanbio Co. Ltd., outside the submitted work; In addition, Hideyuki Okano has a patent on a therapeutic agent for amyotrophic lateral sclerosis and composition for treatment licensed to K Pharma, Inc. Q.S.W is currently an employee of Calico Life Science LLC. Involvement in the presented research was prior to the affiliation. The other authors have declared that no conflict of interest exists. ### Funding Statement This study was supported by the grant support from Japan Society for the Promotion of Science (JSPS) (KAKENHI Grant No. JP21H05278 and JP22K15736 to S.M., JP22K07500 to S.T. and JP20H00485 to H.O.), Japan Agency for Medical Research and Development (AMED) (Grant No. JP22ek0109616, JP23bm1123046, JP23kk0305024 to S.M., JP21wm0425009, JP22bm0804003, JP22ek0109616, JP23bm1423002 to H.O.)., and Miyata Yukihiko Memorial ALS Research Grant Foundation to S.M., research grant of Kanae Foundation for the Promotion of Medical Science to S.M., Okasan-Kato Foundation Research Grant to S.M. and Yoshio Koide Grant, Japan ALS Association to S.M., and Daiichi Sankyo Foundation of Life Science to S.M. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the Institutional Review Board of Keio University School of Medicine (approval No. 20080016), and written informed consent was obtained from the participants. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.