Autoimmunity against the beta(2) adrenergic receptor and muscarinic-2 receptor in complex regional pain syndrome

作者：Kohr Danielle; Singh Pratibha; Tschernatsch Marlene; Kaps Manfred; Pouokam Ervice; Diener Martin; Kummer Wolfgang; Birklein Frank; Vincent Angela; Goebel Andreas; Wallukat Gerd; Blaes Franz^*

来源：Pain, 2011, 152(12): 2690-2700.

DOI：10.1016/j.pain.2011.06.012

• Complex regional pain syndrome
• Autoantibodies
• Autoimmunity
• Autonomic nervous system
• beta(2) adrenergic receptor
• Muscarinic-2 receptor

Complex regional pain syndrome (CRPS) is a painful condition affecting one or more extremities of the body, marked by a wide variety of symptoms and signs that are often difficult to manage because the pathophysiology is incompletely understood. Thus, diverse treatments might be ineffective. A recent report revealed the presence of autoantibodies against differentiated autonomic neurons in CRPS patients. However, it remained unclear how the antibodies act in the development of CRPS. We therefore aimed to characterize these antibodies and identify target antigens. Functional properties of affinity-purified immunoglobulin G of control subjects or CRPS patients were assessed using a cardiomyocyte bioassay. Putative corresponding receptors were identified using antagonistic drugs, and synthesized peptide sequences corresponding to segments of these receptors were used to identify the target epitopes. Chinese hamster ovary cells were transfected with putative receptors to ensure observed binding. Further, changes in the intracellular Ca2+ concentration induced by agonistic immunoglobulin G were measured using the Ca2+-sensitive fluorescent dye fura-2 assay. Herein, we demonstrate the presence of autoantibodies in a subset of CRPS patients with agonistic-like properties on the beta(2) adrenergic receptor and/or the muscarinic-2 receptor. We identified these autoantibodies as immunoglobulin G directed against peptide sequences from the second extracellular loop of these receptors. The identification of functionally active autoantibodies in serum samples from CRPS patients supports an autoimmune pathogenesis of CRPS. Thus, our findings contribute to the further understanding of this disease, could help in the diagnosis in future, and encourage new treatment strategies focusing on the immune system.

• 出版日期2011-12