Introduction:
Leptin is an important adipokin that is synthesized in accordance with the amount
of fat stored in adipocytes and contributes centrally to energy homeostasis.[1] However,
elevated plasma leptin levels have been shown to adversely influence immune response
by enhancing proinflammatory cytokine secretion and thus increasing oxidative stress.[2]
Oppositely, immunosuppressive states have been associated with leptin depletion.[3]
Most studies dealing with this interconnection focus on obesity, however, there is
only few data regarding anorexia nervosa (AN) patients and athletes available. We
aimed to evaluate the plasma leptin, inflammation and oxidative stress levels in a
cohort of females of divergent energy states.
Methods:
107 females (18 – 40 years) of various energy status groups (anorexia nervosa AN,
normal weight NW, overweight OW, obese OB, and athletes AT) were enrolled. C-reactive
protein (CRP) and interleukin 6 (IL-6) were chosen as inflammation marker and determined
in plasma by a particle enhanced turbidimetric assay. Total oxidant capacity (T0C)
that refers to the total of peroxides and leptin were measured in serum samples by
ELISAs.
Results:
The BMI range was 13.24 to 46.89 kg/m2. Leptin levels differed significantly between the groups (p < 0.001) and correlated
with the BMI (rs= 0.863, p < 0.001), the inflammation marker CRP (rs= 0.576, p < 0.001) and IL-6 (rs= 0.522, p < 0.001), and T0C (rs= 0.387, p < 0.001). Group comparisons revealed significantly higher CRP levels in
OB (OB:AN/NW/AT p < 0.001, OB:OW p = 0.003), significantly higher T0C in OB compared
to AN (p < 0.001) and NW (p = 0.001) and lower T0C in AN compared to AT (p = 0.021).
Conclusion:
In our study population an increase of plasma leptin levels was associated with elevated
inflammation markers and oxidative stress, supporting the proposed proinflammatory
ability of leptin found in cell and animal models. Although inflammation marker were
not elevated in AT, T0C was strikingly high. This might be explained by the enhanced
exercise burden. No striking deviations in AN could be observed. Further research
in clinical settings focusing on specific immune marker and taking nutritional anti-oxidant
status into account is needed to investigate the interconnection of leptin on the
immune system.
References:
[1] Farooqi I, O'Rahilly S. Leptin: a pivotal regulator of human energy homeostasis.
Am J Clin Nutr 2009 Mar;89(3):980S-984S
[2] Perez-Perez A., Vilarino-Garcia T. et.al.: Role of leptin as a link between metabolism
and the immune system. Cytokine Growth Factor Rev 2017 Jun;35:71 – 84.
[3] Francisco V., Pino J. et al.: Obesity, Fat Mass and Immune System: Role for Leptin.
Front Physiol 2018 Jun 1;9:640.
