SMPDL3B a novel biomarker and therapeutic target in myalgic encephalomyelitis.
Rostami-Afshari, Bita, Elremaly, Wesam, Franco, Anita et al. · Journal of translational medicine · 2025 · DOI
Quick Summary
Researchers identified a protein called SMPDL3B that appears to be elevated in people with ME/CFS and linked to symptom severity. This protein is found in the blood at higher levels in ME patients, particularly in women, and seems to be influenced by hormones and immune system dysfunction. The study also tested two existing diabetes medications (vildagliptin and saxagliptin) in the laboratory and found they could potentially help restore balance to this protein, suggesting a possible new treatment approach.
Why It Matters
This research identifies a measurable biological marker that correlates with ME/CFS severity, potentially enabling better disease assessment and patient stratification. The finding that existing medications might modify SMPDL3B activity offers a promising lead for repurposing approved drugs to treat immune dysfunction in ME, which could accelerate drug development timelines.
Observed Findings
ME patients showed significantly elevated plasma SMPDL3B levels that correlated with symptom severity in both cohorts.
Reduced membrane-bound SMPDL3B on monocytes was accompanied by increased PLCXD1 expression and elevated plasma PI-PLC.
Female ME patients displayed higher plasma SMPDL3B levels than male patients, an effect partially mediated by estrogen.
Estradiol upregulated SMPDL3B expression in vitro, indicating hormonal regulation.
Vildagliptin and saxagliptin reduced soluble SMPDL3B and restored membrane-bound SMPDL3B in laboratory assays through PI-PLC inhibition.
Inferred Conclusions
SMPDL3B represents a key biomarker for ME severity and immune dysregulation, influenced by both hormonal and enzymatic (PI-PLC) regulation.
Dysregulation of SMPDL3B cleavage from cell membranes may be a fundamental mechanism contributing to immune dysfunction in ME.
DPP-4 inhibitors vildagliptin and saxagliptin warrant clinical investigation as potential therapeutic agents to restore membrane-bound SMPDL3B and reduce immune dysfunction.
Remaining Questions
Do elevated SMPDL3B levels directly cause immune dysfunction in ME, or are they a consequence of underlying immune activation?
Will vildagliptin and saxagliptin produce clinical benefit in ME patients, and at what doses and for which patient subgroups?
What This Study Does Not Prove
This study does not prove that SMPDL3B elevation causes ME/CFS symptoms—it only shows correlation. The in vitro drug testing demonstrates theoretical potential only; it does not establish that vildagliptin or saxagliptin will be effective or safe when given to ME patients clinically. Sex differences observed may reflect hormonal influences rather than fundamental disease mechanisms.