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  • Title: Impairment of agonist-induced M2 muscarinic receptor activation by autoantibodies from chagasic patients with cardiovascular dysautonomia.
    Author: Beltrame SP, Carrera Páez LC, Auger SR, Sabra AH, Bilder CR, Waldner CI, Goin JC.
    Journal: Clin Immunol; 2020 Mar; 212():108346. PubMed ID: 31954803.
    Abstract:
    Previous studies showed that circulating autoantibodies against M2 muscarinic receptors (anti-M2R Ab) are associated with decreased cardiac parasympathetic modulation in patients with chronic Chagas disease (CD). Here we investigated whether the exposure of M2R to such antibodies could impair agonist-induced receptor activation, leading to the inhibition of associated signaling pathways. Preincubation of M2R-expressing HEK 293T cells with serum IgG fractions from chagasic patients with cardiovascular dysautonomia, followed by the addition of carbachol, resulted in the attenuation of agonist-induced Gi protein activation and arrestin-2 recruitment. These effects were not mimicked by the corresponding Fab fractions, suggesting that they occur through receptor crosslinking. IgG autoantibodies did not enhance M2R/arrestin interaction or promote M2R internalization, suggesting that their inhibitory effects are not likely a result of short-term receptor regulation. Rather, these immunoglobulins could function as negative allosteric modulators of acetylcholine-mediated responses, thereby contributing to the development of parasympathetic dysfunction in patients with CD.
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