Cholinergic Dysfunction in Patients with Psoriatic Arthritis and Immunocompetent Controls: A Cross-sectional Study

Background: The parasympathetic system and its main neurotransmitter, acetylcholine, contributes to homeostasis of inflammation. Cholinergic dysregulation is thought to contribute to the pathogenesis of inflammatory rheumatic diseases. Cholinesterase activity in patients with psoriatic arthritis (PsA) has not been investigated. Objectives: To compare the cholinesterase activity in patients with PsA and immunocompetent controls and to explore the correlation between cholinergic status (CS) and PsA disease activity. Methods: Serum acetylcholinesterase (AChE) and total cholinesterase activity were measured in patients with PsA (n=88) and matched controls (n=84). Cholinergic activity before and 3-6 months after the initiation of a biologic treatment was evaluated in seven patients with PsA. Results: The levels of AChE and CS were similar in both PsA patients and controls. PsA patients treated with biologies had significantly lower levels of AChE and CS compared to patients treated with non-biologies: 447.4 vs. 526 substrate hydrolyzed/min/ml, P= 0.005, and 1360.9 vs. 1536, P= 0.029, respectively. We found an association between C-reactive protein levels, AChE activity (r = 0.291, P = 0.008), and cholinergic status (r = 0.247, P = 0.026) in patients with PsA but not in controls. No correlation between AChE activity, cholinergic status, and the indices of PsA disease activity was found. After initiating or switching biologic treatment in 7 patients, AChE levels remained stable. Conclusions: We demonstrated similar cholinesterase activity in patients with psoriatic arthritis and controls, highlighting a potential effect of biologic treatment on cholinergic activity in patients with PsA.