Digoxin and digoxin-like immunoreactive factors (DLIF) modulate the release of pro-inflammatory cytokines

Cardiac glycosides such as digoxin and their endogenous counterpart digoxin-like immunoreactive factor (DLIF) may possess anti-inflammatory properties. Pro-inflammatory cytokines from human peripheral blood mononuclear cells (PBMC) were measured by ELISA using specific antibodies. Immunocytochemistry was used to localize NF-kB. Non-stimulated PBMC constitutively secreted minimum amounts of cytokines. LPS (1 mg/L) stimulation lead to steep increases in TNF-alpha, IL-6 and IL-8 concentrations with peak rises at 8 h. An 8 h delay was observed for IL-10. Increases in IL-10 were sustained for18 h period. Significant inhibition (P > 0.05) of TNF-alpha, IL-6 and IL-8 at non-toxic of digoxin concentration (< 100 nM) and DLIF (10 nM digoxin equivalent (de)) was observed whereas no such effect was seen for IL-10. Inhibition of the degradation of activated NF-kB in the PBMC was observed with the indicated concentrations of digoxin, DLIF or Pyrrolidine dithiocarbamate (PDTC). Digoxin and DLIF inhibit the release of proinflammatory cytokines from PBMC via NF-kB-dependent pathway suggesting an anti-inflammatory effect.