Pathophysiological Changes in Mice Induced with Autoantibodies to M3 Muscarinic Acetylcholine Receptor

• Main Authors: Miao-Wen Wu, 吳妙文
• Other Authors: Ching-Fong Liao
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/57494917395880197378

碩士 === 國立陽明大學 === 生理學研究所 === 92 === Muscarinic acetylcholine receptors (mAChRs) belong to members of the G protein coupled receptor superfamily with seven hydrophobic transmembrane domains, an extracellular N terminus, three extracellular, and intracellular loops, and an intracellular C terminus. Parasympathetic stimulation can cause increased glandular secretion. The action is through binding of acetylcholine to mAChRs on autonomic organs, such as urinary bladder, pupil, salivary and lacrimal glands, etc. Functional M3 mAChR autoantibodies have been shown to inhibit cholinergic neurotransmission at the postsynaptic level and appear to mediate parasympathetic dysfunction, including sicca symptoms (dry mouth and dry eyes) in Sjögren’s syndrome. In addition to focal lymphocytic infiltration of exocrine glands in histological biopsy, some patients with primary Sjögren’s syndrome have a wide variety of hematological abnormalities such as hemocytopenia. And also there are many kinds of autoantibodies in serum of SS patients, such as rheumatoid factor, antinunuclear antibodies, Ro/SSA ribonucleoprotein, La/SSB ribonucleoprotein, anti-M3 antibodies and so on. However, so far it is unknown what kinds of antibodies induced systemic syndrome in SS patients. In this study, we raised antibodies against the second extracellular loop of the M3 mAChR (hM3e2) and tested the pathophysiological changes in the animal. Peptides of hM3e2, which is identical to the mouse M3 mAChR, were used to immunize the C57BL/6J female mouse. The autoantibodies produced were detected by enzyme-linked immunosorbent assay. The M3 mAChR-regulated organs were analyzed. The results indicated that 1) some hematocrit levels decreased and some increased in the hM3e2-immunized mice, as well as not related to the antibody titer. 2) High percentage of echinocytes was present in the blood smear of the immunized mice. 3) Echinocytes were induced in vitro by incubation of normal red blood cells with anti-hM3e2 antibodies. 4) The spleens enlarged in the immunized mice. 5) Spleen section showed that the sizes of white pulps and red pulps were increased in the immunized mice. 6) Pilocarpine-stimulated saliva production was not altered in the hM3e2-immunized mice. 7) The mucosal and submucosal layers of urinary bladder were highly hyperplasia and looked like “villi”. 8) There were no focal lymphocytic infiltration in the urinary bladder and submandibular salivary gland in the immunized mice. In summary, the mice with anti-M3e2 autoantibodies showed some pathophysiological properties related to M3 mAChR dysfunction.