Association between IL-15 and insulin plasmatic concentrations in patients with pulmonary tuberculosis and type 2 diabetes.

IL-15 is part of the immune response in pulmonary tuberculosis (PTB) but amazingly, it may also induce physiological effects similar to those of insulin. We evaluated the IL-15 and insulin plasmatic levels in adults with PTB and with or without type 2 diabetes mellitus (DM2), who received previous antituberculosis therapy for at least 2 months. We analyzed the concentrations of glucose, glycated hemoglobin, insulin, as well as levels of IL-15, IL-2, IFN-γ, and TNF-α in patients with PTB, patients with PTB-DM2, household contacts with DM2 (C-DM2), and healthy household contacts (H-C). Our results showed unexpected high levels of glucose, insulin, and IL-15 in the PTB and C-DM2 groups. In comparison, low levels of these same indicators were observed in the PTB-DM2 and H-C groups. Interestingly, our analysis showed a positive correlation of IL-15 with insulin in the PTB group (r = 0.73) and in the C-DM2 group (r = 0.66). In comparison, a weak correlation between IL-15 and insulin was observed in the PTB-DM group (r = 0.10) and in the H-C group (ρ = 0.26). Our results suggest an association between IL-15 and insulin levels in the patient with PTB. Intriguingly, this association was weaker in the patient with PTB-DM2.

IL-15 that a regulator of TNF-α in patients with diabetes mellitus type 2.

Diabetes mellitus type 2 (DM2), obesity, and the metabolic syndrome are considered that a low-grade chronic inflammatory condition. Although synthesis of different pro- and anti-inflammatory cytokines has been implicated in this process, this low-grade inflammatory condition is characterized especially by an increase in Tumor Necrosis Factor alpha (TNF-α), a cytokine that has been associated to the development of insulin resistance and muscle wasting in the diabetic patients. In consequence, mechanisms implicated in attenuating the deleterious effects of TNF-α are activated. One of these mechanisms may involve interleukin 15 (IL-15), which has proven effect on intermediate metabolisms, regulating blood glucose and lipid levels, and diminishing proteolysis in striated muscle. This suggests that the induction of endogenous IL-15 production by a simple event as physical activity may aid in decreasing or even inhibiting the negative effects of TNF-α in patient with DM2 or obesity, in which a low grade chronic inflammatory condition is present.