Figure 4. HDAC-inhibitory activity of butyrate decreases pro-inflammatory cytokine expression within DC to promote Treg induction.

a) Histone acetylation in Flt3L-elicited DC from B6 mice treated with the indicated SCFA (500 μM) or TSA (10 nM) for 6 h followed by acid extraction of histones from isolated nuclei, SDS-PAGE and blotting with antibody for pan-acetylated H3. Total histone H3 served as a loading control. Shown below is the relative acetylated H3 band intensity calculated over total H3 and normalized as fold over untreated.

b) Induction of Foxp3 expression upon stimulation of naïve CD4⁺ T cells by CD3 antibody in the presence of SCFA or TSA, Flt3L-elicited DC and TGF-β. DC were cultured with titrated amounts SCFA or TSA for 6 h, washed and co-cultured with FACS-purified naïve CD4⁺ T cells in the presence of CD3 antibody and TGF-β. The data are shown as percent CD4⁺ cells expressing Foxp3 after 4 days of culture. Data are representative of at least 2 independent experiments.

c) RelB gene expression quantified by qPCR in purified Flt3L-elicited DC from B6 mice treated for 6 h with SCFA or TSA, as in (a). Data are representative of 4 independent experiments.

d) RelB gene expression quantified by qPCR in purified Flt3L-elicited DC from B6 mice treated with or without TSA in combination with, or in the absence of, butyrate at the indicated concentrations.

Data in this figure are representative of at least 2 independent experiments, unless otherwise noted. The data represent mean +/- SEM.