Epigenetic Mechanisms of the Anti-inflammatory Action of the Opioid Peptide Leutragin: Role of Sirtuin 1

Sirtuin 1 (SIRT1) is a class III histone deacetylase that plays a key role in resolving inflammation through known epigenetic mechanisms involving histone and nuclear factor κB (NF-κB) deacetylation. Deacetylation reduces the transcriptional activity of NF-κB and the associated production of pro-inflammatory cytokines such as interleukin 1β (IL-1β), tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). In the present study, we show for the first time that biomodeling of acute lung inflammation by a single injection of lipopolysaccharide (LPS) induces synchronous oscillations of mRNA levels of cytokines IL-1β, TNF-α, IL-6 and SIRT1 deacetylase in the lungs, the maximum amplitudes of cytokine mRNA oscillations are observed between 1.5 and 5 hours, whereas high levels of SIRT1 mRNA are observed up to 24 hours, when cytokine mRNA oscillations have already faded, which is consistent with the hypothesis about the role of SIRT1 as a factor acting in the phase of inflammation resolution. The study shows that the mechanism of anti-inflammatory action of inhaled hexapeptide Leutragin, a δ-opioid receptor agonist, is related to its ability to increase SIRT1 mRNA expression and decrease the amplitudes of IL-1β, TNF-α, and IL-6 mRNA oscillations in the lungs, which generally leads to the resolution of inflammation in the conditions of biomodeling of acute lung inflammation.