Anti M3 Muscarinic Actylcholine Receptor Antibodies in Systemic Lupus Erythematosus and Sjogren Syndrome: Association with other Autoantibodies and Clinical Manifestations

CECILIA PISONI; SILVIA REINA; ALICIA EIMON; CAROLINA CARRIZO; ENRI BORDA

Congreso; 10th International Congress on SLE- Lupus 2013; 2013

Introduction: antibodies against M3 muscarinic actylcholine receptors (mAChRs) have been described in patients with Sjogren syndrome (SS). Little is known about these antibodies in systemic lupus erythematosus (SLE) patients. The aim of this study was to describe the levels of anti M3 mAChR in patients with SLE and SS, associations with other auto-antibodies and clinical manifestations.  Patients and Methods: patients with SLE and primary SS were included. Serum autoantibodies against M3 mAChR synthetic peptide were measured by ELISA (normal value: Mean: 0.26; SD: 0.01). Anti-Ro, anti-La, anti-Sm and anti nRNP were tested by double-diffusion. Anti dsDNA was tested by critidia lucillae IFI assay. Clinical variables were analyzed in SLE patients only, activity score was measured by Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and damage by Systemic Lupus International Collaborating Clinics (SLICC) damage score. Student?s t test and Mann-Whitney test were used to analyze continuous variables.  Results: 32 patients with SLE and 21 patients with SS were studied. Forty seven (88.7%) were female. Mean age at diagnosis was 37.6 ± 12.9. Levels of anti M3 mAChR in SLE patients were mean 0.73 ± SD 0.75 and in SS mean 1.18 ± 0.52 p 0.02.  Table 1 shows the anti M3 mAChR antibodies titer and its association to other autoantibodies in the total population (SLE and SS).                                                            anti M3 mAChR Mean anti M3 mAChR SD p Anti-Ro negative (21) 0.55 0.65   Anti-Ro positive (32) 1.14 0.64 0.002         Anti-Sm negative (52) 0.92 0.70   Anti-Sm positive (1) 0.14 0.00 0.27         Anti -La negative (42) 0.88 0.77   Anti-La positive (11) 1.00 0.31 0.16         Anti-nRNP negative  (48) 0.97 0.70   Anti-nRNP positive (5) 0.33 0.39 0.05         Anti dsDNA negative (49) 0.90 0.67   Anti dsDNA positive (4) 0.96 1.12 0.86   No associations were detected between levels of anti M3 mAChR and SLEDAI ≥6 p 0.18 or SLICC ≥ 1 p 0.87. Patients with SLE and hematological manifestations had levels of anti M3 mAChR median 0.79 (range 0.11- 3.7) and those without had median 0.16 (range 0.13-0.74) p 0.05.  Conclusions: Anti M3 mAChR levels were significantly higher in SS compared to SLE. In the total population (SS and SLE) patients with anti-Ro and nRNP positive had higher levels of anti M3 mAChR. In SLE patients those with hematological manifestations had significantly higher antibody levels.