P. falciparum exposure drives epigenetic reprogramming of monocyte/macrophages toward a regulatory phenotype.

Monocytes of U.S. adults (n = 4) were incubated with medium, RBC or Pf-iRBC for 24 hours and then analyzed by chromatin immunoprecipitation (ChIP) and RT-PCR to quantify H3K4me3 enrichment at (A) TNF and (D) IL-6 promoter sites. Replicate monocytes were incubated with medium, RBC or Pf-iRBC, washed at 24 hours, and incubated for 3 days in human serum to permit Mf differentiation. On day 5, cells were analyzed by ChIP and RT-PCR to quantify H3K4me3 enrichment at (B) TNF and (E) IL-6 promoter sites. Finally, replicate monocytes were incubated with medium, RBC or Pf-iRBC, washed at 24 hours, incubated for 3 days in human serum, co-cultured with Pf-iRBC for 24 hours, and analyzed by ChIP and RT-PCR to quantify H3K4me3 enrichment at (C) TNF and (F) IL-6 promoter sites. Kinetics of H3K4me3 enrichment at (G) TNF and (H) IL-6 promoter sites across indicated timepoints. Results are shown as means ±SEM fold enrichment of H3K4me3 antibody as percent of input. (A-F) One-way ANOVA with Tukey’s adjustment for multiple comparisons. P values indicate level of significance. (G, H) Two-way ANOVA with Tukey’s adjustment for multiple comparisons. P values indicate level of significance between Pf-iRBC vs. medium and Pf-iRBC vs. RBC, respectively.