ObjectiveTo observe the changes of serum cytokines in patients with neuromyelitis optic neuromyelitis optic spectrum disorder (NMOSD) associated optic neuritis (NMOSD-ON) before and after intravenous methylprednisolone pulse (IVMP) treatment. MethodsA prospective clinical study. From November 2020 to December 2021, 24 NMOSD-ON patients who visited the Neuro-Ophthalmology Clinic of Beijing Tongren Hospital Affiliated to Capital Medical University were included. Among them, 9 patients were male; 15 patients were female. According to the detection results of aquaporin 4 (AQP4) immunoglobulin G (IgG) antibody (AQP4-IgG) in peripheral blood, the patients were divided into AQP4-lgG positive group and AQP4-lgG negative group, which were 10 and 14 cases respectively. Twenty healthy volunteers were selected as control group. Age (F=0.639) and sex (χ2=2.373) composition ratio of the three groups were compared, the difference were not statistically significant (P=0.504, 0.333). All patients were treated with 500 mg/d or 1 000 mg/d IVMP. Peripheral venous blood of all subjects, and quantitatively analyze interferon-gamma (IFN-γ), interleukin (IL)- 4, IL-31, IL-33, IL-17A, IL-6, IL-21, IL-23, IL-10, tumor necrosis factor (TNF)-α level in serum with Luminex FLEX MAP 3D liquid-phase suspension chip detection system were collected. The differences among groups were analyzed by one-way ANOVA and Kruskal Wallis H test. ResultsBefore IVMP treatment, serum IL-17A concentrations in AQP4-lgG positive group, AQP4-lgG negative group and control group were 2.39, 2.17 and 1.97 pg/ml, respectively. TNF-α concentrations were 5.60, 4.17 and 5.89 pg/ml, respectively. Compared with control group, serum IL-17A concentration in AQP4-IgG positive group was increased, while TNF-α concentration in AQP4-IgG negative group was decreased, with statistical significance (H=12.720, 10.900; P=0.040, 0.039). The levels of IL-17A, IL-6 and other cytokines did not change significantly. After IVMP treatment, serum IL-6 in AQP4-lgG positive group and AQP4-lgG negative group were 0.72 pg/ml and 0.73 pg/ml, respectively. TNF-α concentrations were 4.17 pg/ml and 3.88 pg/ml, respectively. IFN-γ concentrations were 2.15 pg/ml and 2.55 pg/ml, respectively. Compared with before treatment, serum levels of IL-6, TNF-α and IFN-γ in AQP4-lgG positive patients were significantly decreased, with statistical significance (Z=－2.668, －2.547, －2.201; P=0.008, 0.011, 0.028). Serum levels of IL-6 and TNF-α were significantly decreased in AQP4-lgG negative patients, and the difference was statistically significant (Z=－2.501, －1.978; P=0.012, 0.048). ConclusionGlucocorticoid may play a therapeutic role by affecting the levels of serum IL-6, TNF-α, IFN-γ in patients with NMOSD-ON.