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)-gamma, interleukin (IL)-1beta, IL-6, IL-10, IL-12 and transforming growth factor (TGF)-beta1. The results were statistically analyzed. RESULTS The lipopolysaccharide (LPS) stimulation significantly elevated levels of IFN-gamma, IL-1beta, 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.