Association of cigarette smoking with neuromyelitis optica-immunoglobulin G sero-positivity in neuromyelitis optica spectrum disorder

Background: Neuromyelitis optica spectrum disorder (NMOSD) is a neuroinflammatory demyelinating disease caused by the presence of a highly specific serum autoantibody marker, NMO-immunoglobulin G (NMO-IgG), that reacts against the water channel aquaporin-4 (AQP4). The present study examined the association between NMO-IgG sero-positivity and environmental factors such as cigarette smoking. Methods: A cross-sectional study was conducted in Sina Hospital, a tertiary referral center in Tehran, Iran. All the patients with a definite diagnosis of NMOSD were involved in this study. The enzyme-linked immunosorbent assay (ELISA) was used to examine the AQP4-IgG status. To assess the association between NMO-IgG sero-positivity and cigarette smoking, a researcher-made questionnaire covering patients’ lifestyle information on smoking habits was designed and administered using the structured face-to-face interviews with the patients. Results: The positive and negative NMO-IgG results were found in 44 (46.8%) and 50 (53.2%) patients, respectively. The increased NMO-IgG sero-positivity odds were observed among the lifetime smokers [odds ratio (OR) = 3.24, 95% confidence interval (CI): 1.16-9.08], current smokers (OR = 6.08, 95% CI: 1.26-29.39), and passive smokers (OR = 2.22, 95% CI: 1.10-4.50). Conclusion: Lifetime and current smoking as well as passive smoking can be regarded as risk factors for NMO-IgG sero-positivity. Smoking with its immunological effects can lead to the production of autoantibodies such as NMO-IgG.