Association of serum eosinophil-derived neurotoxin with amyotrophic lateral sclerosis

Introduction: Neuroinflammation is critical in the pathogenesis of amyotrophic lateral sclerosis (ALS). Eosinophil-Derived Neurotoxin (EDN) is an eosinophil granule-derived secretory protein having ribonuclease activity. Higher levels of Eosinophil-Derived Neurotoxin (EDN) in ALS patients suggest it may take part in the pathogenesis of ALS as an inflammatory biomarker and serve as an ALS indicator. Measuring serum EDN level in ALS patients may be helpful for early diagnosis as well as early therapeutic trials. The objective of this study was to find out the association of Eosinophil-Derived Neurotoxin (EDN) with amyotrophic lateral sclerosis (ALS). Methodology: This case-control study was done in the Department of Neurology, Bangladesh Medical University, Dhaka, from December 2019 to March 2021. A total 54 subjects, 27 ALS patients and 27 age- & sex matched control group (CG), were enrolled after satisfying the selection criteria. According to El Escorial diagnostic criteria, ALS patients were sub-grouped into definite, probable (lab-supported) and possible ALS. Severity was assessed by ALS functional rating scale-revised (ALSFRS-R). Then quantitative estimation of serum EDN level of both cases and controls was done by ELISA Kit in the Department of Microbiology and Immunology Laboratory, BSMMU, Dhaka. Results: The mean EDN in ALS cases (13.5±SD 4.05) was higher than the control group (5.72± SD 3.25), (P-value <0.001). The level of EDN was significantly increased by 2.36-fold in the sera of patients with ALS as compared with the control group. EDN level also differentiates definite, probable (Lab supported) and possible ALS from the control group (EDNDefinite– 13.60±3.84, EDNCG – 5.72±3.25; p<0.001. EDNProbable – 14.43±4.27, EDNCG – 5.72±3.25 p<0.001, and EDNPossible – 9.97±3.84, EDNCG – 5.72±3.25; p<0.05). Receiver operating characteristic (ROC) curve analysis showed that EDN reliably differentiated ALS patients from the control group with a cut-off value of 10.3 ng/ml, exhibiting 77.8% sensitivity and 88.9% specificity. Conclusion: EDN was found to be significantly increased in ALS patients than the control group. Thus, EDN level measurement might help in early diagnosis of ALS as well as a possible therapeutic trial.