Investigation of Inflammation in Fibromyalgia After a Lipopolysaccharide-Induced Immune Response

Fibromyalgia (FM) is a debilitating chronic pain disorder characterized by widespread musculoskeletal pain. The exact cause of FM is unknown, but current research suggests that an overactive immune response may be involved. The purpose of this study was to examine pathophysiological responses to a low-level immune insult, using in-vivo administration of lipopolysaccharide (LPS). Thirteen women with FM and 13 age-matched healthy controls (HC) completed the study. Blood samples were collected before participants received 0.3ng/kg or 0.4ng/kg endotoxin and 3 hours after. We conducted a mixed analysis of variance (ANOVA) with time as the within-subjects factor (pre-LPS, post-LPS) and the study group as the between-subject factor (FM, HC). LPS dosage was included as another between-subjects factor. A statistical significance threshold of p < 0.05 was used for all analyses. We found no significant interactions with IL-6 or TNF-α outcomes, but we did find a significant group-by-time interaction with CRP (F [1,22] = 4.068, p =.032). An abnormally sensitized reaction to low-level immune insults may be involved in the symptoms of FM. This study is not sufficient to conclusively establish whether fibromyalgia involved irregular inflammatory reactions. Our results suggest further research into immune responses in FM is warranted. This trial was registered at clinicaltrials.gov (NCT04263454) and funded by the American Fibromyalgia Syndrome Association.