Correlation of multiple sclerosis severity, expression of ferroptosis genes and products of lipid peroxidation in patients

Abstract

Introduction: Increasing interest in relatively novel iron and lipid peroxidation dependent cell death, ferroptosis, as a possible neurodegeneration modulator, lead us and others to investigate ferroptosis related molecular background in multiple sclerosis (MS). We recently determined ferroptosis related genetic signature with regard to MS course. Objectives/Aims: To further understand clinical relevance of differentially expressed genes we aimed to correlate clinical parameters of MS severity and lipid peroxidation products with gene expression in mild relapse-remitting (RRMS) and severe secondary progressive (SPMS) subgroups of patients. Methods: Neurological impairment was scored by expanded disability status scale (EDSS). Disease severity was presented as multiple sclerosis severity score (MSSS). Study included 48 patients, 24 in each group with minimum ten years of disease duration. Gene expression was determined using AmpliSeq™ Library PLUS for Illumina® and iSeqT 100 System on RNA samples isolated from peripheral blood mononuclear cells. Raw read counts had been normalised by the DESeq2 algorithm workflow. Lipid peroxidation product 4-hydroxynonenal (4-HNE) was quantified in plasma. Results: We found positive correlation of EDSS with 4-HNE (Spearman R 0.57, p=0.01) in RRMS and surprisingly opposite one in SPMS (Spearman R -0.48, p=0.02). Due to narrow EDSS range within MS groups we used MSSS for correlation with gene expression. MSSS correlated with expression of SLC7A11 gene (Spearman R -0.42, p=0.04), in RRMS. In SPMS, MSSS significantly correlated with expression of SLC11A2, GCH1 and EGLN2 genes (Spearman R: 0.52, p=0.009; 0.58, p=0.002, 042, p=0.04). Although we didn’t observe significant correlation of MSSS with lipid peroxidation products, in SPMS 4-HNE significantly correlated with expression of CDKN1A and SAT1 genes (Spearman R 0.44, p=0.03, both). Conclusion: In conclusion, clinical parameter of MS severity was associated with expression of key ferroptosis genes and therapeutic targets, such as SLC7A11. In SPMS, more prominent correlation was found with iron related (SLC11A2) and genes that regulate cell cycle and proliferation, along with positive correlation of unfavourable gene expression with products of lipid peroxidation. Having in mind preliminary nature of the current Results: it is required to validate them in larger groups of patients.