Tehran University of Medical Sciences Journal of Sleep Sciences 2476-2938 1 2 2016 07 27 44 50 EN Demeke Debebe Department of Immunology, School of Medicine, Tehran University of Medical Sciences International Campus, Tehran, Iran Khosro Sadeghniat-Haghighi Occupational Sleep Research Center, Baharloo Hospital, Tehran University of Medical Sciences, Tehran, Iran Yadollah Shakiba Department of Immunology, School of Medicine, Kermanshah University of Medical Science, Kermanshah, Iran Ania Rahimi Golkhandan Occupational Sleep Research Center, Baharloo Hospital, Tehran University of Medical Sciences, Tehran, Iran Maryam Izad Department of Immunology, School of Medicine, International Campus, Tehran University of Medical Sciences,Tehran, Iran 2015 12 03 2016 02 29 Background and Objective: Narcolepsy is a chronic neurological disorder caused by loss of hypocretin (Hcrt) neurons. Both genetic and environmental factors play an important role for the development of narcolepsy. The mechanism of Hcrt loss in narcolepsy is elusive; however, an autoimmune mediated destruction of Hcrt neurons is suspected. The purpose of this study was to assess Th17 related cytokines: interleukin-6 (IL-6), IL-17, IL-23, and transforming growth factor beta (TGF-β) in the pathophysiology of narcolepsy and other types of excessive daytime sleepiness (EDS). Materials and Methods: A total of 15 narcoleptic patients, 35 other patients with EDS and 48 age and sex matched healthy subjects were enrolled in this case-control study. Serum IL-6, IL-17, IL-23, and TGF-β levels were measured using sandwich enzyme-linked immunosorbent assay. Results: There was no significant difference in IL-6 (P = 0.0618) and IL-23 (P = 0.7717) level among participants with narcolepsy, other patients with EDS and controls, whereas TGF-β was significantly decreased in the ones with narcolepsy and other EDS compared to healthy controls (P = 0.0039). Conclusion: Decreased level of TGF-β in narcolepsy and other patients with EDS indicates a clue for the presence of dysregulation of inflammatory cascades in these patients. This study sheds a new insight on the pathophysiology of narcolepsy. https://jss.tums.ac.ir/index.php/jss/article/view/15 https://jss.tums.ac.ir/index.php/jss/article/download/15/24