These investigations demonstrate that serum antibodies against muscarinic acetylcholine receptors (mAChR) in primary Sjögren syndrome (pSS) and associated Sjögren syndrome (aSS) bind and activate both cholinergic receptors of M 3 in salivary gland and M 1 in neonatal myocardium and in the cerebral frontal cortex area subtypes; triggering the production of the second messengers and proinflammatory mediators related to mAChR activation. In this way the cholinergic autoantibodies damages these

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... ptors, which thus starts acting as an antigen. On this basis M 3 and M 1 mAChR IgG can be considered new markers of pSS/aSS allowing the differentiation between dry eye and mouth of autoimmune and non-autoimmune nature. Given that cholinergic autoantibodies also deregulate the parasympathetic system of the target organs, they can also be seen as a new factor contributing to the etiopathology of the syndrome.