Pirfenidone inhibits macrophage infiltration in 5/6 nephrectomized rats

Abstract

Tubulointerstitial macrophage infiltration is a hallmark of chronic kidney disease involved in the progression of renal fibrosis. Pirfenidone is a newly identified antifibrotic drug, the potential mechanism of which remains unclear. The aim of this study was to investigate the effects of pirfenidone on M1/M2 macrophage infiltration in nephrectomized rats. Nephrectomized rats were treated with pirfenidone by gavage for 12 wk. Twenty-four hour urinary protein, N-acetyl-␤-Dglycosaminidase (NAG) activity, systolic blood pressure, and C-reactive protein were determined. Paraffin-embedded sections were stained for CD68, CCR7, and CD163 macrophages. Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1␣ (MIP-1␣), as well as M1 and M2 macrophages secretory markers, were evaluated by real-time RT-PCR and Western blotting analysis. Pirfenidone significantly improved the elevated proteinuria and NAG activity from week 2 onward after surgery. Pirfenidone attenuated interstitial fibrosis and decreased expression of fibrotic markers including transforming growth factor-␤ 1, connective tissue growth factor, ␣-smooth muscle actin, fibronectin, and fibroblast-specific protein-1. Pirfenidone significantly decreased the infiltrating macrophages. The number of M1 and M2 macrophages was significantly lower after pirfenidone treatment. MCP-1 and MIP-1␣ were increased in nephrectomized rats at mRNA and protein levels. Pirfenidone treatment significantly inhibited their expression. The TNF-␣, IL-6, and nitric oxide synthases-2 expressed by M1 macrophages were increased in nephrectomized rats, and pirfenidone significantly attenuated their expression. Pirfenidone treatment also significantly decreased arginase-1, dectin-1, CD206, and CD86 expressed by M2 macrophages. Thus pirfenidone inhibits M1 and M2 macrophage infiltration in 5/6 nephrectomized rats, which suggests its efficacy in the early and late periods of renal fibrosis.

Improved Mitochondrial Function Underlies the Protective Effect of Pirfenidone against Tubulointerstitial Fibrosis in 5/6 Nephrectomized Rats

“…However, the precise anti-fibrosis mechanism of this drug is not clear. Our previous study in the same animal model found that fibronectin was decreased significantly after pirfenidone treatment [21]. The present study successfully demonstrated that pirfenidone improved renal functions and ameliorated tubulointerstitial fibrosis by preventing mitochondrial dysfunction in renal tubular cells.…”

TGF-β signaling in the kidney: profibrotic and protective effects

“…Pirfenidone's effects are, in part, mediated via inhibition of TGF-␤1 synthesis (78). In the kidney, the effects of pirfenidone in suppressing renal fibrosis have been shown in several experimental models including diabetic nephropathy, unilateral ureteral obstruction (UUO), and subtotal nephrectomy (9,74,82). An open-label, single-center pilot study demonstrated that pirfenidone significantly slowed renal function decline rate in patients with FSGS, with a median improvement of 25% in patients who have moderate to severe CKD and are already being treated with angiotensin antagonists (11).…”

Therapeutic targets for treating fibrotic kidney diseases

“…The compound exerts anti-fibrotic and anti-inflammatory activities in a variety of animal and cell-based models, and its effects are, in part, mediated by inhibition of TGF-β1 synthesis. 37 The effect of pirfenidone in reducing renal fibrosis has been demonstrated in several experimental models including unilateral ureteral obstruction (UUO), 38 subtotal nephrectomy, 39-41 and diabetic nephropathy. 42 The antifibrotic effects of pirfenidone have also been demonstrated in other models of tissue fibrosis such as bleomycin-induced pulmonary fibrosis.…”