Effect of Insulin on Hydrogen Peroxide Production by Human Polymorphonuclear Leukocytes

Abstract

This study evaluated the effect of insulin on the respiratory burst of human polymorphonuclear leukocytes (PMNLs) and the signalling pathways involved in this process, especially the involvement of protein kinase C (PKC). Isolated human PMNLs from healthy volunteers were incubated with different concentrations of insulin (10^-10-10^-7 mol/l) and for different durations of incubation (5-90 min). The intracellular production of hydrogen peroxide (H₂O₂) was detected employing a previously validated flow cytometric assay using 2’,7’-dichlorofluorescein-diacetate (DCFH-DA) as a marker for H₂O₂production. Specificity of insulin action was verified using an insulin antagonist (the monoclonal antibody MA-10). To identify the signalling pathway involved, we used: (a) monoclonal antibody MA-5, directed against the α-subunit of the insulin receptor, that partially mimics insulin without activating tyrosine kinase; (b) H7, an inhibitor of PKC involved in O₂^- production in PMNLs, and (c) phorbol myristate acetate (PMA) that binds and stimulates PKC. Insulin caused a dose- and time-dependent stimulation of H₂O₂ release by human PMNLs. The effect of insulin was blocked by MA-10. The actions of insulin and PMA on H₂O₂ release were additive, whereas the actions of MA-5 and PMA were not. H7 partially inhibited the H₂O₂ production stimulated by insulin and completely inhibited MA-5 action. We conclude that insulin stimulates, in a dose- and time-related manner, the respiratory burst of human PMNLs. PKC activation can only partially account for the intracellular mechanisms involved in this process.

Insulin-stimulated chemokinesis in normal human neutrophils is dependent on D-glucose concentration and sensitive to inhibitors of tyrosine kinase and phosphatidylinositol 3-kinase

“…In the different forms of diabetes, insulin levels can be either low (type-1 diabetes) or elevated due to insulin resistance (type-2 diabetes) [18]. The effect of insulin on the in vivo and in vitro functions of neutrophils from diabetics and healthy individuals is still obscure [7,10,11,[19][20][21][22]. Recently, however, it was found that insulin could stimulate chemokinesis in normal human neutrophils [19].…”

Insulin increases resistance to burn wound infection-associated sepsis

“…Specifically, Dandona and colleagues (40) proposed that insulin may develop its anti-inflammatory effects via reduction of intranuclear NF-κB and simultaneous stimulation of its inhibitor IκB. Flow cytometry studies of human leukocytes have shown insulin receptors on lymphocytes, monocytes, and neutrophils (41), and insulin has been found to increase the functions of activated lymphocytes (42, 43) and neutrophils (44) and to enhance the proliferation and differentiation of T cells (43). These data suggest that insulin may have some direct effects on certain immune cell populations.…”

Einfluss der Tonsillektomie auf metabolische Kontrolle und Insulinbedarf bei erwachsenen Diabetikern

“…Ebenso entscheidend ist die Tatsache, dass eine bessere Stoffwechseleinstellung sogar mit einer geringeren Insulindosis erreicht werden konnte. Dies ist insofern von Bedeutung für den weiteren Krankheitsverlauf eines Patienten, als dass Insulin selbst an der Entwicklung von Komplikationen, besonders der Mikroangiopathieentstehung, mitbeteiligt sein kann [16]. Die gute Stoffwechseleinstellung nach Ablauf von 3 Monaten zeigt den positiven Einfluss der Sanierung des chronischen Entzün-dungsfocus auf den längerfristigen Therapieerfolg bei Diabetikern.…”