Системная склеродермия (ССД) харак-теризуется чрезмерным фиброзообразовани-ем, микроангиопатией и наличием циркули-рующих антител к различным аутоантигенам.Патогенез ССД до сих пор полностью не изу-чен. В частности, остается не до конца выяс-ненной роль аутоиммунитета в развитии кли-нико-патогенетических фенотипов. 418Научно-практическая ревматология. 2016(54)4:418-423 О р и г и н а л ь н ы е и с с л е д о в а н и я Objective: to estimate frequency of autoantibodies in a cohort of Russian patients with systemic sclerosis (SS) and to investigate clinical associations of these autoantibodies. Subjects and methods. In 2012 to 2015, the investigation enrolled 300 patients (58 men and 242 women) who fulfilled the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) SS criteria. All patients underwent immunological examination including determination of antinuclear antibodies, anti-topoisomerase I (anti-Scl-70) antibodies, anti-centromere antibodies (ACA), anti-U1-ribonucleoprotein antibodies (anti-U1 RNP), and anti-RNP III antibodies. Results and discussion. The vast majority of patients were middle-aged females with moderate disease duration. There was a preponderance of patients with limited cutaneous form (55.3%); 37.4% patients had diffuse SS; 5.9% had overlap syndrome; and <1% had visceral and juvenile SS. The vast majority (83.8%) of patients were found to have antinuclear factor. Among the SS-associated antibodies, anti-Scl-70 were most common and were revealed in approximately one-half of the patients. ACA was present in only 44 (14.6%) patients. There was a combination of positivity for ACA and anti-Scl-70 antibodies in 3 patients with limited cutaneous SS, including one with an early form of the disease. 26 patients had anti-U1 RNP antibodies. Among them, there was a preponderance of patients with limited cutaneous SS and overlap syndrome. Anti-RNP III antibodies were found in 5.5% of cases, mainly in those with limited cutaneous SS; these were observed in one patient with diffuse SS and interstitial lung disease. No kidney injury was seen in this patient group. Conclusion. The characteristics of the Russian cohort are the preponderance of the limited cutaneous SS and the frequent detection of anti-Scl-70 antibodies in both diffuse and limited cutaneous SS; no correlation of anti-Scl-70 antibodies with rapid progression of the pathological process, with kidney disease. PROFILE OF AUTOANTIBODIES IN SYSTEMIC SCLEROSIS

Systemic scleroderma (SSD) is a clinically heterogeneous disease characterized by obliterating microangiopathy, autoimmune activation, and fibrosis of the skin and viscera. Interstitial lung fibrosis (ILF) is a characteristic visceral injury in SSD and considered to be a main cause of disability and death. The diagnosis of SSD-associated ILF is made on the basis of a cluster of symptoms, physical examination, external respiratory function changes, and high-resolution computed tomography. Pulmonary fibrosis is included in the 1980 American College of Rheumatology (ACR) classification criteria and in the joint ACR and 2013 European League against Rheumatism diagnostic criteria. According to the definition given in these criteria, pulmonary fibrosis in SSD is described as bilateral changes, most pronounced in the basal lung segments, which are not a sign of primary lung disease. The paper describes a case of a SSD patient with a complete spectrum of characteristic signs of unilateral pulmonary fibrosis. This case is the first description of unilateral ILF in SSD and shows the need for ruling out connective tissue diseases, primarily SSD, when such lung changes concurrent with extrapulmonary manifestations are detected.

Systemic lupus erythematosus, systemic sclerosis, inflammatory myopathy and rheumatoid arthritis are systemic connective tissue disorders which are characterized by heterogeneous clinical symptoms and variable course. To date, updated diagnostic criteria for early diagnosis of each of the diseases of this group have been proposed. At the same time, a proportion of patients already have at the onset of the disease or over time, a combination of signs characteristic of different diseases. Such conditions are referred to as mixed connective tissue disease, undifferentiated connective tissue disease or overlap-syndrome, whose nosological identity remains the subject of discussion. Formerly there has been a kind of terminological confusion and similar conditions were described under different names, depending on the author's preferences. It was also believed that these conditions were an early stage or a clinically "incomplete" form of a connective tissue disease. However, as the observations of large patient groups have shown, whose disease was represented by a number of individual signs of several connective tissue diseases, the clinical manifestation remains unchanged for many years in the majority of them. To recognize the right for nosological independence, one should account for the fact that only for a mixed connective tissue disease various authors and research groups have proposed four variants of diagnostic criteria. These criteria have small differences in the number of clinical signs; however, all criteria include a mandatory sign, i.e. the presence of antibodies to U1-ribonucleoprotein in high titers. Clinical signs common to all these diagnostic criteria include the Raynaud's syndrome, arthritis, myositis and finger swelling or sclerodactyly. Another patient category includes those with mono- or oligosymptomatic manifestations characteristic of systemic connective tissue diseases, but without any specific immunological markers. Some of these patients in a fairly short time, usually from several months to 1–2 years, develop other clinical symptoms and signs corresponding to a reliable diagnosis of a connective tissue disease. At the same time, a significant part of patients with the oligosymptomatic course demonstrate a long-term stability without any further evolution of the disease. Such cases are defined as an undifferentiated connective tissue disease. To avoid the erroneous diagnosis of the transient form or an early stage of any connective tissue disease, the proposed classification criteria, along with the inclusion criteria, also embrace clinical and serological exclusion criteria. A separate category consists of patients with a combination of clinical signs sufficient for a definitive diagnosis of at least two systemic connective tissue diseases. These patients are diagnosed with the overlap-syndrome with indication of the components of connective tissue diseases in each individual case, as it largely determines the individual treatment and prognosis. The possibility of such clinical variants of systemic connective tissue diseases is becoming increasingly justified due to the concept of polyautoimmunity, which has attracted great interest of researchers in the last few years.

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