Serum from Fibromyalgia Patients Activates Satellite Glial Cells in Mouse Peripheral Ganglia

Fibromyalgia (FM) is a complex syndrome associated with chronic widespread pain and with various other symptoms, including sleep and mood disturbances. Its under-lying causes are not fully understood, and the lack of diagnostic blood tests and im-aging, along with the absence of definitive treatments, makes management challenging. Recent studies showed that immunoglobulins in the blood of FM patients activate satellite glial cells (SGCs) in mouse dorsal root ganglia (DRG), leading to pain behaviors in mice after passive transfer. Here, we aimed to determine whether serum from FM patients activates mouse SGCs in DRGs and other ganglia that may be involved in FM’s diverse symptoms. Serum from FM patients (N=15) and healthy controls (HC, N=8) was collected. Sera were incubated with different types of mouse sensory ganglia: DRG, trigeminal ganglion (TG), the nodose ganglion (NG), and the superior cervical sympathetic ganglion (Sup-CG). SGC activation was assessed by immunostaining of SGCs for the glial activation marker glial fibrillary acidic protein (GFAP). We compared this response between male and female mice. All the ganglia tested, DRG, TG, NG, and Sup-CG, showed induced upregulation of GFAP labeling in SGCs after incubation with FM serum compared with HC, indicating SGC activation by the se-rum. Similar responses were observed in both male and female mice. We conclude that serum from FM patients contains factor(s) that can activate SGCs across various types of mouse ganglia, which may reflect the diverse symptom profile of FM. These findings provide objective evidence of pathogenic factor(s) that could serve as a foundation for a diagnostic method for FM and require further purification and identification, hopefully paving the way for future targeted FM therapy.