Article
Imbalanced levels of circulating autoantibodies targeting muscarinic acetylcholine receptors in patients with systemic lupus erythematosus and systemic sclerosis
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Published: | August 29, 2016 |
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Background: Muscarinic acetylcholine receptors belong to the family of G protein-coupled receptors and comprise several subtypes such as M1-M5. They are part of the parasympathetic nervous system but can also be found on non-neuronal cells including immune cells. It has become evident that autoantibodies directed against some of these receptors are involved in the pathogenesis of certain autoimmune diseases, for instance autoantibodies targeting M3 in primary Sjögren's Syndrome. In addition, dysregulated levels of autoantibodies against muscarinic acetylcholine receptors have been reported recently in patients with Chronic Fatigue Syndrome (CFS). CFS is a frequent clinical manifestation in patients with connective tissue diseases (CTDs) such as systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). However, whether patients with SLE and SSc have imbalanced levels of autoantibodies targeting muscarinic acetylcholine receptors remains to be investigated.
Methods: Sera from patients with SLE (n = 249), SSc (n = 376) and healthy control subjects (n = 198) were analyzed for the presence of autoantibodies against muscarinic cholinergic receptors (M1-4) using enzyme linked immunosorbent assay (ELISA).
Results: Patients with SLE demonstrated significantly elevated concentrations of autoantibodies recognizing M1-4 compared to healthy controls. In turn, patients with SSc showed increased titers of autoantibodies directed against M1 only and decreased levels of anti-M2 and -M4.
Conclusion: Imbalanced levels of autoantibodies targeting muscarinic cholinergic receptors in patients with SLE and SSc may explain why CFS is frequently developing in these patients. However, the mechanisms triggered by autoantibodies targeting muscarinic cholinergic receptors in patients with SLE and SSc remain to be further investigated.