TNF-α regulates diabetic macrophage function through the histone acetyltransferase MOF
Aaron D. denDekker, Frank M. Davis, Amrita D. Joshi, Sonya J. Wolf, Ronald Allen, Jay Lipinski, Brenda Nguyen, Joseph Kirma, Dylan Nycz, Jennifer Bermick, Bethany B. Moore, Johann E. Gudjonsson, Steven L. Kunkel, Katherine A. Gallagher
Aaron D. denDekker, Frank M. Davis, Amrita D. Joshi, Sonya J. Wolf, Ronald Allen, Jay Lipinski, Brenda Nguyen, Joseph Kirma, Dylan Nycz, Jennifer Bermick, Bethany B. Moore, Johann E. Gudjonsson, Steven L. Kunkel, Katherine A. Gallagher
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Research Article Immunology Inflammation

TNF-α regulates diabetic macrophage function through the histone acetyltransferase MOF

Abstract

A critical component of wound healing is the transition from the inflammatory phase to the proliferation phase to initiate healing and remodeling of the wound. Macrophages are critical for the initiation and resolution of the inflammatory phase during wound repair. In diabetes, macrophages display a sustained inflammatory phenotype in late wound healing characterized by elevated production of inflammatory cytokines, such as TNF-α. Previous studies have shown that an altered epigenetic program directs diabetic macrophages toward a proinflammatory phenotype, contributing to a sustained inflammatory phase. Males absent on the first (MOF) is a histone acetyltransferase (HAT) that has been shown be a coactivator of TNF-α signaling and promote NF-κB–mediated gene transcription in prostate cancer cell lines. Based on MOF’s role in TNF-α/NF-κB–mediated gene expression, we hypothesized that MOF influences macrophage-mediated inflammation during wound repair. We used myeloid-specific Mof-knockout (Lyz2Cre Moffl/fl) and diet-induced obese (DIO) mice to determine the function of MOF in diabetic wound healing. MOF-deficient mice exhibited reduced inflammatory cytokine gene expression. Furthermore, we found that wound macrophages from DIO mice had elevated MOF levels and higher levels of acetylated histone H4K16, MOF’s primary substrate of HAT activity, on the promoters of inflammatory genes. We further identified that MOF expression could be stimulated by TNF-α and that treatment with etanercept, an FDA-approved TNF-α inhibitor, reduced MOF levels and improved wound healing in DIO mice. This report is the first to our knowledge to define an important role for MOF in regulating macrophage-mediated inflammation in wound repair and identifies TNF-α inhibition as a potential therapy for the treatment of chronic inflammation in diabetic wounds.

Authors

Aaron D. denDekker, Frank M. Davis, Amrita D. Joshi, Sonya J. Wolf, Ronald Allen, Jay Lipinski, Brenda Nguyen, Joseph Kirma, Dylan Nycz, Jennifer Bermick, Bethany B. Moore, Johann E. Gudjonsson, Steven L. Kunkel, Katherine A. Gallagher

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Figure 4

TNF-α promotes MOF expression in vitro and in wound macrophages.

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TNF-α promotes MOF expression in vitro and in wound macrophages. (A) Rep...
(A) Representative figure showing induction of Mof expression by TNF-α in BMDMs. BMDMs were isolated from C57BL6/J mice and stimulated in culture with 25 ng/mL TNF-α for 0, 2, 6, and 10 hours. Mof expression was measured by qPCR (n = 3/time point, repeated twice). (B) Representative figures showing induction of inflammatory cytokine gene expression by TNF-α. BMDMs were isolated from C57BL6/J mice and stimulated in culture with 25 ng/mL TNF-α for 12 hours. Il1b and Tnf expression were measured by qPCR (n = 3, repeated twice). (C) Representative figures showing induction of Mof expression by TNF-α in splenic and wound macrophages. Monocyte/macrophage (CD11b+CD3–CD11c–CD19–Ly6G–NK1.1–) single-cell suspensions were MACS sorted from C57BL/6J mouse spleens and stimulated ex vivo with 25 ng/mL TNF-α for 12 hours. Wound macrophages (CD11b+CD3–CD19–Ly6G–) were MACS sorted at day 5 after injury from C57BL/6J mice and stimulated ex vivo with 25 ng/mL TNF-α for 12 hours. Mof expression was measured by qPCR in both splenic and wound monocytes/macrophages (n = 3 mice pooled/replicate, repeated twice). (D) Representative figure showing H4K16ac deposition on Il1b promoter in response to TNF-α stimulation. Wound macrophages (CD11b+CD3–CD19–Ly6G–) were isolated on day 5 after wounding from C57BL/6J mice, and ChIP analysis was performed for H4K16ac at the NF-κB binding site on the Il1b promoter (n = 6 mice, repeated three times). A was analyzed by 1-way ANOVA followed by Tukey’s test for multiple comparisons. B–D were analyzed using a 2-tailed Student’s t test.