Objective:

To evaluate serum levels of Tfh and Th17 related cytokines/molecules in patients with myasthenia gravis (MG).

Background:

The role of cytokines associated with Th1 and Th2 cells in the pathogenesis of myastenia gravis (MG) is well-studied. However, there is no data about the role of Tfh and Th17-related cytokines in MG pathogenesis.

Design/Methods:

Blood samples were collected from generalized MG patients in remission (MG), and from MG patients with myasthenic crisis (cMG) before rescue treatment (plasmapheresis or IVIg) and 24 hours after the last dose/session of the treatment. The disease severity and treatment response were assessed by MGFA classification. Serum levels of IL-21, IL-22, IL-17A, CXCL13, sPD-L1, sICOSLG and sCD40L were analyzed by ELISA.

Results:

Ten MG patients in remission and twelve cMG patients (6 treated with IVIg, 6 with plasmapheresis) were included. CXCL13 levels tended to be lower in MG patients (p=0,056) and it was inversely correlated with disease severity (r=0,429, p<0,05). However, IL-17A levels were significantly higher in cMG patients (p<0,001) and correlated with disease severity (r=0,678, p=0.001). sPDL1, sICOSLG, IL22 levels did not differ between MG and cMG groups. In addition, significant decrease was observed in sPDL1, sICOSLG and CXCL13 serum levels in treated cMG patients (p<0,05), regardless of the treatment method, whereas IL22 levels increased significantly after treatment (p<0,05).

Conclusions:

High serum IL-17A levels seem to contribute to disease severity of MG. Decrease in serum CXCL13 level after treatment may demonstrate its role in myasthenic crisis. Lastly, increase in serum IL-22 levels after treatment, highlight its protective effect in MG.