Antifibrotic activity of an inhibitor of histone deacetylases in DOCA-salt hypertensive rats

Abstract

Background and purpose: Histone deacetylases (HDACs) silence genes by deacetylating lysine residues in histones and other proteins. HDAC inhibitors represent a new class of compounds with anti-inflammatory activity. This study investigated whether treatment with a broad spectrum HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA), would prevent cardiac fibrosis, part of the cardiovascular remodelling in deoxycorticosterone acetate (DOCA)-salt rats.

Experimental approach: Control and DOCA-salt rats were treated with SAHA (25 mg x kg(-1) x day(-1) s.c.) for 32 days. Changes in cardiovascular structure and function were assessed by blood pressure in vivo and in Langendorff perfused hearts, ventricular papillary muscle and in aortic rings in vitro. Left ventricular collagen deposition was assessed by histology.

Key results: Administration of SAHA to DOCA-salt rats attenuated the following parameters: the increased concentration of over 20 pro-inflammatory cytokines in plasma, increased inflammatory cell infiltration and interstitial collagen deposition, increased passive diastolic stiffness in perfused hearts, prolongation of action potential duration at 20% and 90% of repolarization in papillary muscle, development of left ventricular hypertrophy, systolic hypertension and changes in vascular dysfunction.

Conclusions and implications: The HDAC inhibitor, SAHA, attenuated the cardiovascular remodelling associated with DOCA-salt hypertensive rats and improved cardiovascular structure and function, especially fibrosis, in the heart and blood vessels, possibly by suppressing inflammation. Control of cardiac histone or non-histone protein acetylation is a potential therapeutic approach to preventing cardiac remodelling, especially cardiac fibrosis.

Figure 2

Densitometric measurement of relative concentrations in rat plasma of cytokines/chemokines based on % optical density of positive control. Plasma from DOCA and DOCA + SAHA-treated rats. All values are mean ± SEM of three independent experiments (*P < 0.05, **P < 0.01, ***P < 0.001).

Figure 1

Suppression of inflammatory cytokines by SAHA treatment in vivo. Serum cytokines from (A) DOCA-treated rats (B) DOCA + SAHA-treated rats. Each blot represents three independent experiments and is numbered 1, IL1a; 2, CINC2a/b; 3, IL17; 4, IP10; 5, IL2; 6, TNFα; 7, IL4; 8, MIP1a; 9, IFNγ; 10, IL13; 11, IL1b; 12, CINC3; 13, IL1ra; 14, CNTF; 15, IL3; 16, GMCSF; 17, IL6; 18, CINC1; 19, RANTES; 20, thymus chemokine; 21, TIMP1; 22, LIX; 23, fractalkine; 24, L-selectin; 25, VEGF; 26, MIG; 27, sICAM; 28, IL10; 29, MIP3; 30 (control).

Figure 3

Picrosirius red staining of left ventricular perivascular collagen deposition (A–D) and of left ventricular interstitial collagen deposition (E–H) (magnification, ×40) in UNX (A, E), DOCA (B, F), UNX + SAHA (C, G), DOCA + SAHA (D, H)-treated rats. Summary data (n= 4–5) of the histology are shown below for left ventricular perivascular collagen (I) and interstitial collagen (J) deposition (#P < 0.05 vs. UNX; *P < 0.05 vs. DOCA); collagen is stained light red.

Figure 4

Haematoxylin and eosin staining of infiltrating inflammatory cells of left ventricular interstitial region (magnification, ×40) in UNX (A), DOCA (B), UNX + SAHA (C), DOCA + SAHA (D)-treated rats.

Figure 5

Cumulative concentration–response curves for noradrenaline (A), sodium nitroprusside (B) and acetylcholine (C) in thoracic aortic rings from UNX, DOCA, UNX + SAHA and DOCA + SAHA-treated rats (#P < 0.05 vs. UNX; *P < 0.05 vs. DOCA).