To investigate the in vitro activation of NF-κB (nuclear factor kappa B) and STAT3 pathways in central memory CD4+ T (CD45RA- CD62L+, Tcm) cells of MOGAD patients after antigen and cytokine stimulation or glucocorticoid treatment compared to age-matched healthy controls (HC).

There is increasing evidence that T cells play a key role in MOGAD. Proinflammatory cytokines IL6 and TNFα, activators of STAT3 and NF-κB pathways, respectively, are reported to increase in CSF of MOGAD patients and increase during infections, which commonly precede MOGAD relapses, We previously found decreased A20, a negative regulator of NF-κB, serum levels at relapse. 

4 pediatric MOGAD remission samples (untreated) and 4 sex and age-matched HC were studied. 8×10⁴ PBMCs were plated per well. Cells were stimulated with MOG peptides, anti-CD3/CD28, TNFα, IL6, or PMA/Ionomycin. A20, IκBα (inhibitor kappa B-alpha), p-p65 (phospho-p65), and p-STAT3 (phospho-STAT3) expression levels (MFI, mean fluorescence intensity) were determined by flow cytometry and MFI levels in Tcm. 

Ex vivo expression levels of A20, IκBα, p-p65, and p-STAT3 levels were not significantly different in MOGAD compared to HC in Tcm. Upon short IL6 or TNFα (0-15/7-75 minutes) stimulation, we observed similar NF-κB and STAT3 activation in the Tcm, while STAT3 activation was significantly higher at 75 minutes in MOGAD. MOG peptide stimulation for 24 hours decreased A20 and IκBα levels and increased p-STAT3 and p-p65 levels in both MOGAD and HC. When co-incubated with either MOG peptide or CD3, prednisolone decreased NF-κB and STAT3 activation. 

MOG peptide stimulation activates STAT3 and NF-κB in CD4+Tcm cells from MOGAD and HC, while prednisolone treatment had the opposite effect. IL6 and TNFα also activate Tcm similarly in MOGAD and HC, while STAT3 activation was more extended in MOGAD. Modulating the NF-κB-A20 or IL6/STAT3 pathway in T cells may have therapeutic potential in MOGAD.