Hyperleptinemia as a marker of various phenotypes of obesity and overweight in women with rheumatoid arthritis and systemic lupus erythematosus

Abstract

Objective – to identify different phenotypes of overweight in women with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) based on body mass index (BMI) and serum leptin levels, as well as to determine the frequencies of various metabolic disorders, hypertension and cardiovascular complications in individual phenotypes. Material and methods. The study included 50 women with RA and 46 with SLE aged 18 to 65 years without a history of diabetes and fasting hyperglycemia. The concentration of leptin (ELISA), insulin (electrochemiluminescence analysis) was determined in all patients, and the HOMA-IR index was calculated. Hyperleptinemia was diagnosed at leptin concentrations >11,1 ng/ml, insulin resistance (IR) – at HOMA-IR values ≥2,77. Three main phenotypes of overweight were distinguished: “classic” (BMI≥25 kg/m2  + hyperleptinemia), “healthy” (BMI≥25 kg/m2 , without hyperleptinemia), “hidden” or “latent” (BMI<25 kg/m2  + hyperleptinemia), as well as “normal weight” (BMI<25 kg/m2 , without hyperleptinemia). Results. Patients with RA and SLE were similar in age (p=0.4), disease duration (p=0.2) and BMI (p=0.5). Hyperleptinemia was found in 46% of women with RA and 74% – with SLE (p=0.005), IR – in 10% and 22% of patients, respectively (p=0.2). The “classic” phenotype of overweight was diagnosed in 30%, “healthy” – in 8%, “hidden” – in 16% of cases with RA and in 44%, 0% and 30% of cases with SLE, respectively. IR was found in 3%, hypertension – in 6% of patients with “normal weight”. With the “classical” phenotype, IR (29%) and hypertension (66%) were more common than with “normal weight” (p<0.01 in all cases), with the “hidden” phenotype, significant differences were obtained only in hypertension frequency (45%; p=0.0012), but not IR (18%). 3 out of 4 women with a history of cardiovascular complications suffered from “classic” overweight, one patient had a “normal weight”. Conclusion. In women with SLE up to 65 years of age, the frequency of hyperleptinemia, but not IR, is higher than in patients with RA. In both diseases, the “classic” overweight phenotype is most common. In RA, a “hidden” phenotype was detected less often than in SLE, at the same time, a “healthy” phenotype is not characteristic of SLE. The frequencies of metabolic disorders and hypertension is low with the “normal weight” and “healthy” phenotype, high – with the “classic”, intermediate – with the “hidden” phenotype.