Background Systemic lupus erythematosus (SLE) is an autoimmune rheumatic disease that usually develops in women aged 18-50 years. It is known that age at onset modifies the clinical manifestations of SLE, and so the elderly may form a specific patient subgroup. It is now well established that the serum levels of the cytokines interleukin (IL) 6 and IL10 are increased in patients with SLE (1).
Objectives The primary aim was to compare the type of clinical involvement and autoantibodies in patients with late-onset (LO) or early-onset (EO) SLE. The second aim was to compare IL6 levels in the two patient groups and their possible correlations with clinical and immunological manifestations.
Methods Fifty-five patients meeting the American College of Rheumatology (ACR) criteria for the classification of SLE (47 F, 8 M) were consecutively enrolled. They were evaluated for the presence and intensity of clinical manifestations and laboratory abnormalities, and divided into two subgroups on the basis of the age of onset of SLE symptoms. The patients who developed SLE at or after the age of 65 years were considered LO-SLE cases. Antinuclear antibodies (ANA) and anti-double-stranded DNA (dsDNA) were detected by means of indirect immunofluorescence respectively using HEp-2 cells and Crithidiae luciliae as a substrate. Anti-extractable nuclear antigen (anti-ENA) antibodies (anti-Sm, anti-Ro/SSA and anti-La/SSB) were tested by means of counter-immunoelectrophoresis using control sera provided by the Center for Disease Control (Atlanta, USA). Serum IL6 levels were measured using the Quantikine high sensitivity human IL6 immunoassay (R & D Systems Europe, Abingdon, Oxon., UK).
Results Twenty-five patients hadLO-SLE and 30 EO-SLE. The female to male ratio was similar in the two goups (9:1 vs. 8:1). The LO-SLE patients were more likely to have arthritis (88% vs 82%; p =0.813) and serositis (28% vs 13%; p=0.34). The prevalence of the other SLE manifestations was lower in the LO-SLE patients: malar rash (60% vs 82%; p =0.176), nephropathy (3% vs 10%; p =0.245), photosensitivity (35% vs 82%; p=0.176), alopecia (15% vs 82%; p= 0.0001) and Raynaud’s phenomenon (32% vs 70%; p=0.001). The LO-SLE patients had a higher prevalence of anti-SSA (52% vs 33%; p= 0.162), ANA antibodies (30% vs 27%; p=0.295) and were more frequently affected by secondary Sjogren syndrome (SS) (44% vs 16%; p= 0.001). Thee prevalence of other antinuclear antibodies was lower in LO-SLE than in EO-SLE (anti-dsDNA: 74,3% vs. 78,8%, anti-Sm 17,1% vs. 20%; all p=n.s; anti-SSB (24% vs 66%, p=0.002).IL6 levels were significantly higher (p=0.005) in the patients with LO-SLE, and there was a correlation between IL6 levels and secondary SS (p = 0.002, r =20.26).
Conclusions Patients with LO-SLE tend to have a less severe clinical picture than those with EO-SLE; however, they frequently suffer from secondary SS. The increased IL6 levels in the patients with EO-SLE may influence the development of secondary SS. These findings are in line with those of increasing number of studies supporting the existence of physiological links between IL6 and SLE and SS, but further analyses are required to confirm them.
Eilertsen GØ, et al. Interleukin-6promotes arthritis and joint deformation in patients with systemic lupus erythematosus. Lupus. 2011;20:607-13;
Disclosure of Interest None Declared