Vascular endothelial cell activation and chronic inflammatory processes along with concomitant chronic energy deficiency characterize the steady state of sickle cell disease (SCD). Adipose tissue besides its lipid storage has also an endocrine function producing adipokines most important of which are leptin and adiponectin. These two hormones regulate food intake and energy expenditure but they are also involved in the regulation of inflammatory responses, hematopoiesis and angiogenesis. We evaluated leptin and adiponectin blood levels and determined any possible correlations with disease severity and inflammation markers in steady state SCD patients.
We measured leptin and adiponectin using ELISA as well as high sensitivity C-reactive protein (hs-CRP) using nephelometry, in blood serum of 42 patients (24 male-18 female, median age 34 years, range 29–52 years) with steady state sickle cell/beta thalassemia and 40 healthy individuals matched for age, sex and body mass index (BMI) z-score who served as controls. Steady state was defined as a crisis-free period for at least 4 weeks after the previous clinical event and 3 or more months since the last blood transfusion. After natural logarithmic transformation, the measured values were investigated for correlations against hemoglobin, white blood cells, bilirubin, lactate dehydrogenase (LDH), ferritin, insulin levels, fetal hemoglobin (HbF), number of events/year (severe painful crises, transfusions, severe infections or other complications) and treatment with iron-removing agents or hydroxurea.
Leptin was found significantly lower in patients compared to controls (median±SD, 2.9±1.9 vs 8.5±4.9 ng/ml, p=0.006), whereas adiponectin and hs-CRP were found significantly elevated (median±SD 11.3±6.1 vs 7.5±3.1 μg/ml, p=0.003 and 2.8±1.1 mg/L vs 1.4±0.9; p=0.018, respectively). No correlations were found between adipokines and age, gender, chelation or hydroxurea treatment, ferritin, insulin, HbF, hemoglobin or clinical events. Leptin, but not adiponectin, levels were positively correlated with BMI z-score (r= 0.71, p=0.018) and negatively correlated with LDH levels (r=0.69, p=0.012). Concerning adiponectin, significant positive correlation was noted with hs-CRP levels and white blood cell number (r=0.644, p=0.015 and r=0.68, p=0.028).
Adipokine blood levels are altered in steady state SCD possibly reflecting the effect of chronic hemolytic and inflammatory state on adipose tissue dysfunction. This could be considered as another endocrinopathy that affects SCD patients.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.