Anti-satellite glia cell IgG antibodies in FM patients are related to symptom severity and to metabolite concentrations in thalamus and... 2023 Fanton

Full title: Anti-satellite glia cell IgG antibodies in fibromyalgia patients are related to symptom severity and to metabolite concentrations in thalamus and rostral anterior cingulate cortex

Highlights

• FMS have higher anti-SGC IgG levels compared to healthy controls.
• FMS with high, compared to low, anti-SGC IgG levels have a worse disease status.
• Anti-SGC IgG and metabolite concentrations in rACC and thalamus in FMS are negatively correlated.
• Anti-SGC IgG are not associated with the cerebral processing of evoked pain in FMS.
• Anti-SGC IgG may have a potential CNS-mediated action relative to spontaneous pain.

Abstract

Recent translational work has shown that fibromyalgia (FM) might be an autoimmune condition with pathogenic mechanisms mediated by a peripheral, pain-inducing action of IgG antibodies binding to satellite glia cells (SGC) in the dorsal root ganglia (DRG). A first clinical assessment of the postulated autoimmunity showed that fibromyalgia subjects (FMS) had elevated levels of antibodies against SGC (termed anti-SGC IgG) compared to healthy controls and that anti-SGC IgG were associated with a more severe disease status.

The overarching aim of the current study was to determine whether the role of anti-SGC IgG in driving pain is exclusively through peripheral mechanisms, as indirectly shown so far, or could be attributed also to central mechanisms. To this end, we wanted to first confirm, in a larger cohort of FMS, the relation between anti-SGC IgG and pain-related clinical measures. Secondly, we explored the associations of these autoantibodies with brain metabolite concentrations (assessed via magnetic resonance spectroscopy, MRS) and pressure-evoked cerebral pain processing (assessed via functional magnetic resonance imaging, fMRI) in FMS.

Proton MRS was performed in the thalamus and rostral anterior cingulate cortex (rACC) of FMS and concentrations of a wide spectrum of metabolites were assessed. During fMRI, FMS received individually calibrated painful pressure corresponding to low and high pain intensities.

Our results confirmed a positive correlation between anti-SGC IgG and clinical measures assessing condition severity. Additionally, FMS with high anti-SGC IgG levels had higher pain intensity and a worse disease status than FMS with low anti-SGC IgG levels. Further, anti-SGC IgG levels negatively correlated with metabolites such as scyllo-inositol in thalamus and rACC as well as with total choline and macromolecule 12 in thalamus, thus linking anti-SGC IgG levels to the concentration of metabolites in the brain of FMS. However, anti-SGC IgG levels in FMS were not associated with the sensitivity to pressure pain or the cerebral processing of evoked pressure pain.

Taken together, our results suggest that anti-SGC IgG might be clinically relevant for spontaneous, non-evoked pain. Our current and previous translational and clinical findings could provide a rationale to try new antibody-related treatments in FMS.

Open access, https://www.sciencedirect.com/science/article/pii/S0889159123002672

 

Seems to be a follow up to Fibromyalgia patients with elevated levels of anti–satellite glia cell immunoglobulin G antibodies present with more severe symptoms 2023 Krock et al