Comparative characteristics of the main phenotypes of systemic sclerosis

Abstract

Various clinical and immunological phenotypes of systemic sclerosis (SS) differ in the frequency and severity of manifestations of the disease, the progression of damage to internal organs, and prognosis. The detection rate of anti-U1-ribonucleoprotein (RNP) (anti-U1RNP) antibodies in SSD ranges from 5 to 30%. They are found in various rheumatic diseases (SS, systemic lupus erythematosus, rheumatoid arthritis, polymyositis, and Sjo gren’s syndrome) and are associated with a more favorable course, a good response to treatment (in particular, that with glucocorticoids), and a good prognosis. In SS, the clinical and laboratory associations of anti-U1RNP have been insufficiently investigated. Objective: to compare clinical, laboratory, and instrumental findings in patients with SS positive for anti-U1RNP, anti-topoisomerase-I (anti-Scl70), and anticentromere antibodies (ACA). Subjects and methods. Sixty-five anti-U1RNP antibody-positive patients were selected for a study group (Group 1) from the general database of patients who met the 2013 ACR/EULAR criteria for SS and who were followed up at the V.A. Nasonova Research Institute of Rheumatology in 2012 to 2017. The comparison groups included 50 anti-Scl70 antibody-positive patients with SS (Group 2) and 50 ACA-positive ones (Group 3). Anti-U1RNP negativity was confirmed in patients of the comparison groups. Results and discussion . Most patients in Groups 1 and 3 had the limited type of SS (88 and 94%, respectively) and a chronic course of the disease (82 and 94%) while Group 2 patients showed an acute and subacute course (52%) and predominantly the diffuse type of SS (58%). All the patients with SS had a higher level of antinuclear factor. The feature of the anti-U1RNP positive group was a preponderance of the limited type of the disease with minimal skin damage concurrent with a more frequent involvement of the musculoskeletal system (damages to the joints (65%) and muscles (43%), as well as with the high rate of damage to internal organs (in particular, the lung, heart, and gastrointestinal tract). The patients of this group exhibited high inflammatory and immunological activities, hematological disorders (hypocomplementemia (15%) and leukopenia (14%)). Sjo gren’s syndrome was detected in one-third of these patients. Conclusion. Further study of anti-U1RNP-positive SS will be able to create a management algorithm and to more clearly define the risks and prognosis of the disease for this group of patients.