Effects of insulin and glucose on cytokine production from peripheral blood mononuclear cells

Background: Blood glucose levels should be controlled in patients with critical ill, regardless of whether they are diabetic. Whether hyperglycemia or insulin influences the pro-inflammatory or anti-inflammatory cytokine production in circulating cells remains unclear. In this study, we attempted to identify how hyperglycemia and insulin affect cytokine production in in vitro-stimulated peripheral mononuclear cells (PBMCs). Methods: Nine healthy subjects were enrolled in this study. Cell cultures of stimulated PBMCs were performed with or without glucose or insulin treatment. Supernatants were analyzed for levels of interferon (IFN)-γ, interleukin (IL)-1β, IL-6, IL-10, IL-12 and transforming growth factor (TGF)-β1. The results were statistically analyzed. Results: The lipopolysaccharide (LPS) stimulation significantly elevated levels of IFN-γ, IL-1β, IL-10 and IL-12 from the PBMCs. The IL-12 levels under LPS stimulation were significantly elevated after pretreatment with glucose alone, insulin alone, or a combination of glucose and insulin. However, insulin did not affect the response of IL-12 and other cytokines from hyperglycemic PBMCs. Conclusion: Stimulated PBMCs with hyperglycemic status secreted more IL-12 than those with euglycemic status. Insulin treatment did not influence the IL-12 response from hyperglycemic stimulated PBMCs. More studies are needed to investigate the role of IL-12 in septic patients with hyperglycemia.