Pharmacologic Inhibition of Histone Deacetylase 6 Prevents the Progression of Chlorhexidine Gluconate-Induced Peritoneal Fibrosis by Blockade of M2 Macrophage Polarization

Abstract

Peritoneal fibrosis contributes to ultrafiltration failure in peritoneal dialysis (PD) patients and thus restricts the wide application of PD in clinic. Recently we have demonstrated that histone deacetylase 6 (HDAC6) is critically implicated in high glucose peritoneal dialysis fluid (HG-PDF) induced peritoneal fibrosis, however, the precise mechanisms of HDAC6 in peritoneal fibrosis have not been elucidated. Here, we focused on the role and mechanisms of HDAC6 in chlorhexidine gluconate (CG) induced peritoneal fibrosis and discussed the mechanisms involved. We found Tubastatin A (TA), a selective inhibitor of HDAC6, significantly prevented the progression of peritoneal fibrosis, as characterized by reduction of epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) protein deposition. Inhibition of HDAC6 remarkably suppressed the expression of matrix metalloproteinases-2 (MMP2) and MMP-9. Administration of TA also increased the expression of acetylation Histone H3 and acetylation α-tubulin. Moreover, our results revealed that blockade of HDAC6 inhibited alternatively M2 macrophages polarization by suppressing the activation of TGF-β/Smad3, PI3K/AKT, and STAT3, STAT6 pathways. To give a better understanding of the mechanisms, we further established two cell injured models in Raw264.7 cells by using IL-4 and HG-PDF. Our in vitro experiments illustrated that both IL-4 and HG-PDF could induce M2 macrophage polarization, as demonstrated by upregulation of CD163 and Arginase-1. Inhibition of HDAC6 by TA significantly abrogated M2 macrophage polarization dose-dependently by suppressing TGF-β/Smad, IL4/STAT6, and PI3K/AKT signaling pathways. Collectively, our study revealed that blockade of HDAC6 by TA could suppress the progression of CG-induced peritoneal fibrosis by blockade of M2 macrophage polarization. Thus, HDAC6 may be a promising target in peritoneal fibrosis treatment.

Histone deacetylase 8 inhibition prevents the progression of peritoneal fibrosis by counteracting the epithelial-mesenchymal transition and blockade of M2 macrophage polarization

“…According to previous studies by our group, epigenetic regulation plays an important role in the process of peritoneal fibrosis (6,7,13,14).…”

“…Macrophages play a pivotal role in peritoneal fibrosis process (13). Therefore, we detected the infiltration and polarization of macrophages in a mouse peritoneal fibrosis model established by 4.25% glucose PDF.…”

“…Cells were collected and cultured as described previously (13,16). HPMCs (American Type Culture Collection, ATCC; Rockville, MD, United States) were cultured in Dulbecco's modified Eagle's medium (DMEM) with F12 containing 10% fetal bovine serum (FBS), 1% penicillin, and streptomycin.…”

“…Therefore, we detected the infiltration and polarization of macrophages in a mouse peritoneal fibrosis model established by 4.25% glucose PDF. Western blot showed increased expressions of arginase-1 (Arg-1) and CD163 expression [cell markers of M2 phenotype (13)] after exposure to 4.25% glucose PDF, while PCI-34051 administration effectively decreased their expressions (Figures 6A, C, D). These results suggested that M2 macrophage polarization was involved in the process of peritoneal fibrosis, and the inhibition of HDAC8 by PCI-34051 could prevent M2 macrophage polarization.…”

“…Predominance of M2 macrophage response leads to induction of EMT, and upregulate the production of ECM protein, angiogenesis, and fibrosis (12). Our previous studies have demonstrated that M2 macrophage polarization in the peritoneum is regulated by the phosphorylation of signal transducer and activator of transcription 6 (STAT6) and phosphatidylinositol-3kinase (PI3K)/Akt pathways (13).…”