Objective This study aimed to explore the relationship between systemic inflammation markers and clinical activity, respiratory failure, and prognosis in patients with myasthenia gravis (MG). Methods One hundred and seventeen MG patients and 120 controls were enrolled in this study. Differences in the four immune‐related markers of two groups based on blood cell counts: neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), lymphocyte to monocyte ratio (LMR), and systemic immune‐inflammation index (SII) were measured. The stability of the associations between systemic inflammation markers and respiratory failure in MG patients was confirmed by adjusted logistic regression analysis. Moreover, Kaplan–Meier curve and multivariate COX regression models were applied to assess the factors affecting the outcome of MG. Results NLR, PLR, and SII were higher in MG patients than those in controls and were positively associated with MGFA classification, but not LMR. Adjusted logistic regression analysis showed that PLR was an independent predictor of MG with respiratory failure. The ROC curve demonstrated that PLR showed good sensitivity and specificity for the diagnosis of MG with respiratory failure. Kaplan–Meier curve showed that GMG, positive AchR‐Ab, respiratory failure, high NLR, PLR, SII, and IVIg exposure correlated with the risk for poor outcomes in MG patients. The multivariate COX regression models indicated that GMG and high SII was a risk factor for poor outcome of MG. Interpretation The systemic inflammation markers expressed abnormally in MG patients, in which PLR may be an independent predictor of respiratory failure, and high SII and GMG were predictive risk factors for poor outcomes in MG patients.

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Myasthenia gravis (MG) is an antibody‐mediated autoimmune disorder characterized by fluctuation of fatigue and weakness of muscle. Due to the heterogeneity of the course of MG, available biomarkers for prognostic prediction are urgently needed. Ceramide (Cer) was reported to participate in immune regulation and many autoimmune diseases, but its effects on MG remain undefined. This study aimed to investigate the ceramides expression levels in MG patients and their potential as novel biomarkers of disease severity. Levels of plasma ceramides were determined by ultra performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS). Severity of disease was assessed by quantitative MG scores (QMGs), MG‐specific activities of daily living scale (MG‐ADLs) and 15‐item MG quality of Life (MG‐QOL15). The concentrations of serum interleukin‐1β (IL‐1β), IL‐6, IL‐17A, and IL‐21 were determined by enzyme‐linked immunosorbent assay (ELISA), and the proportions of circulating memory B cells and plasmablasts were detected by flow‐cytometry assay. Four plasma ceramides levels we studied were detected higher in MG patients. And three of them (C16:0‐Cer, C18:0‐Cer, and C24:0‐Cer) were positively associated with QMGs. In addition, receiver operating characteristic (ROC) analysis suggested that plasma ceramides have a good ability of differentiating MG from HCs. Importantly, only C18:0‐Cer was shown to be positively associated with the concentration of serum IL and circulating memory B cells, and the decrease in plasma C18:0‐Cer paralleled the clinical improvement of patients with MG. All together, our data suggest that ceramides may play an important role in the immunopathological mechanism of MG, and C18:0‐Cer has the potential to be a novel biomarker for disease severity in MG.

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