Background IL-6 is one of the cytokines with greater presence in Systemic Sclerosis (SSc) and also one of the key cytokines in the development of atherosclerosis (AS). A recent study (Schiopu E, et al. Rheumatology 2014;53:704–713) has shown a relationship between IL-6 and carotid AS. However, the number of patients was scarce, the results were not confirmed in a multivariate analysis and whether these results are replicable in different populations in different geographical areas has not been tested.
Objectives To assess the relation between plasma IL-6 and AS findings (carotid ultrasound, ankle-brachial index [ABI] and arterial pressure difference between arms) in patients with SSc.
Methods Transverse descriptive study with analytical components. Study population: a cohort of 115 patients with SSc controlled in the Rheumatology Department of a tertiary hospital. Variables: 1) clinical variables; 2) determination of serum IL-6 (IMMULITE 2000; Siemens Healthcare Diagnostics, UK); 4) vascular study: ABI and carotid doppler ultrasound (ESAOTE MyLab XV70, 7–12 MHz linear transducer, software RFQIMT) measuring intima-media thickness (IMT) and presence of atheroma plaques (Mannheim Consensus). A vascular surgeon measured ABI, and the doppler ultrasound was done by a highly experienced rheumatologist, blind to the rest of findings, in a term of 3 months. Statistical analysis: IBM-SPSS Statistics v22.0 package.
Results 115 patients where included consecutively, of which finally 108 were studied; with a mean age of 60,16 years (SD ±15.16); 99 women (91.7%) and 9 men (8.3%). Mean SSc evolution time was 11.45 years (SD ±8.84). LSSc was most frequently diagnosed (50%), followed by SSc without scleroderma (18.5%) and, decreasingly, DSSc (16.7%), overlap syndrome (9.3%) and pre-SSc (5.6%). 38.9% of patients were hypertensive, 46.3% suffered a DL and 6.3% were diabetic. Mean concentrations of serum IL-6 were 4.34 pg/mL (SD ± 5). Mean right IMT was 0.579 mm (SD ± 0.126), and left 0.657 mm (SD ±0.158); 33.3% had atheroma plaque. In total, 37% had a pathological carotid ultrasound and 39.8% macrovascular damage (atheroma plaque and/or IMT>0.9 mm and/or ABI<0.9).
In the bivariate analysis, serum IL-6 was associated to the IMT as well as the presence of atheroma plaque (p-value = 0.002).This association was maintained when jointly considering an ABI<0.9 (p-value = 0.003). Serum IL-6 was also related to the difference in systolic arterial pressure between both arms (r-Pearson =0.236; p-value = 0.022). In the multivariate analysis, the number of atheroma plaques and the macrovascular damage variable maintained statistical significance in the different models.
Conclusions Serum IL-6 concentrations are independently related to the presence of AS and macrovascular disease in patients with SSc. Blocking the action of IL-6 by means of specific therapies could be a therapeutic option which could reduce macrovascular damage in patients with SSc.
Disclosure of Interest None declared