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 underlying causes are not fully understood, and the lack of diagnostic blood tests and imaging, along with the absence of definitive treatments, makes management challenging. Recent studies showed that passive transfer of immunoglobulins from FM patients into mice activated satellite glial cells (SGCs) in mouse dorsal root ganglia (DRG), leading to pain behaviors. Here, we aimed to determine whether whole 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 (HCs, 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). All the ganglia tested, DRG, TG, NG, and Sup-CG, displayed induced upregulation of GFAP labeling in SGCs after incubation with FM serum compared with HCs, indicating SGC activation by the serum. Similar responses were observed in both male and female mice. We conclude that serum from FM patients contains factors that can activate SGCs across various types of mouse ganglia, which may reflect the diverse symptom profile of FM. These findings provide evidence for pathogenic factors 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.