Leptin and soluble leptin receptor changes after pulmonary endarterectomy: relations to cortisol and cytokine network

Leptin is a hormone that regulates food intake. During inflammatory status, leptin may contribute to the anorexia and cachexia of infection. Pulmonary endarterectomy was used as a model of non-infectious cytokine network hyperstimulation. Leptin and soluble leptin receptor (SLR) were compared with evolution of cortisol and inflammatory cytokines in twenty-two patients with chronic thromboembolic pulmonary hypertension treated with pulmonary endarterectomy using cardiopulmonary bypass (CBP) and deep hypothermic circulatory arrest (DHCA). Leptin, SLR, cortisol, IL-beta, IL-6, IL-8, and TNFalpha concentrations in arterial blood were measured before/after sternotomy, last DHCA, separation from bypass, 12, 18, 24, 36, and 48 h after sternotomy. Mean duration of CPB was 338.2 min.; mean circulatory arrest time 39.9 min. The initial decline of leptin, SLR, TNFalpha, IL-6, and IL-8 was followed by an increase culminating 6-24 h after sternotomy. Leptin peak levels were detected 24 h after sternotomy (28.0 ng/ml, 21.9-37.6). IL-6 culminated after separation from CPB, IL-8 was highest 12 h after sternotomy. Leptin concentrations correlated with IL-6 (r=0.82), and TNFalpha (r=0.73). Large cardiovascular surgery caused a significant increase in serum leptin, indicating its acute regulation by stress factors. This effect may be secondary to the inflammatory response mediated via cytokine stimulation. Correlation between leptin and IL-6 indicates the role of IL-6 in leptin induction.