Does leptin stimulate degranulation and respiratory burst in isolated human neutrophils?

REBOLLEDO N ; CIFUENTES M; CORVALÁN C; RAMOS MV; PALERMO MS,; REYES M

Chania, Creta

Congreso; 3rd International Conference on ImmunoMetabolism; 2015

Metabolism Society

Obesity-driven inflammation includes the participation of neutrophils,and leptin has been suggested as a potential inflammatory stimulus of thisacute response. However, data on the inflammatory effect of leptin arecontroversial and have not taken into account donors? characteristics. Isolated blood neutrophils from a sample of male adolescents (12.1y)with different weight status were incubated (30?) with leptin (Invitrogen; 250ng/mL), vehicle (Tris-HCl) or PMA. Inflammatory response was evaluated byassessing degranulation, using flow citometry (surface expression of CD11b andCD66b: ratio leptin/vehicle), and respiratory burst, using fluorometer(production of DCFA from substrate DCFA-DA). Sex- and age-specific body massindex z-scores (BMIz) were calculated using participant?s weight and height.Fasting serum leptin levels were quantified using ELISA. Data are presented asmedian [range]; non-parametric statistic was used. Participants were heterogeneous in BMIz (.8 [-1.3; 3.3]) and leptinlevels (9.8 [3.3; 32.5] ng/mL). Neutrophils incubation with leptin did notincrease the expression of CD11b (.9 [.7; 1.6]) or CD66b(1.0 [.4; 1.2]; n=21). Compared to vehicle, incubation with leptin also failedinducing respiratory burst (.38 [.13; 1.0] uM DCFA vs .33 [.12; 1.1] uM,respectively; p>0.05; n=20). However, vehicle-treated neutrophils showed agreater respiratory burst than non-treated cells (.3 [.13; .52] uM DCFA;p<0.05 compared to vehicle; n=6). PMA-treated cells showed the expectedinflammatory response. Degranulation and respiratory burst did not differ byweight status nor were associated to BMIz or leptin levels of donors. Leptin stimulus was not able to induce an inflammatory response amonghuman neutrophils when using an appropriated control (other studies have usedPBS as control). Our data suggest that in vitro stimulation with leptin is notan inflammatory trigger for neutrophils, even when taking into accountadiposity or leptin levels of donors.