We studied inhibition of
histone deacetylases (HDACs), which results in the unraveling of
chromatin, facilitating increased gene expression.
ITF2357, an orally active, synthetic inhibitor of HDACs, was evaluated as an
anti-inflammatory agent. In
lipopolysaccharide (LPS)-stimulated cultured human peripheral blood mononuclear cells (PBMCs),
ITF2357 reduced by 50% the release of
tumor necrosis factor-alpha (
TNFalpha)
at 10 to 22 nM, the release of intracellular
interleukin (IL)-1alpha at 12 nM, the secretion of IL-1beta at 12.5 to 25 nM, and the production of
interferon-gamma (IFNgamma) at 25 nM. There was no reduction in
IL-8 in these same cultures. Using the combination of
IL-12 plus
IL-18, IFNgamma and
IL-6 production was reduced by 50% at 12.5 to 25 nM, independent of decreased
IL-1 or
TNFalpha. There was no evidence of cell death in LPS-stimulated PBMCs at 100 nM
ITF2357, using assays for
DNA degradation,
annexin V, and
caspase-3/7. By Northern blotting of PBMCs, there was a 50% to 90% reduction in LPS-induced steady-state levels of
TNFalpha and IFNgamma
mRNA but no effect on IL-1beta or
IL-8 levels. Real-time PCR confirmed the reduction in
TNFalpha RNA by
ITF2357.
Oral administration of 1.0 to 10 mg/kg
ITF2357 to mice reduced LPS-induced serum
TNFalpha and IFNgamma by more than 50%. Anti-CD3-induced
cytokines were not suppressed by
ITF2357 in PBMCs either in vitro or in the circulation in mice. In
concanavalin-A-induced
hepatitis, 1 or 5 mg/kg of oral
ITF2357 significantly reduced liver damage. Thus, low, nonapoptotic concentrations of the
HDAC inhibitor ITF2357 reduce pro-inflammatory
cytokine production in primary cells in vitro and exhibit anti-inflammatory effects in vivo.