AT2R agonists C21 and NAc significantly reduced secretion of procollagen 1α1 and fibronectin in human precision cut lung slices stimulated with a fibrotic cocktail (p<0.05).
Do AT2R agonists (C21 and NAc) reduce secretion of ECM proteins in human precision cut lung slices stimulated with a fibrotic cocktail?
AT2R agonists C21 and NAc demonstrated superior efficacy to pirfenidone and comparable efficacy to nintedanib in reducing fibrotic matrix protein secretion in an ex vivo human lung slice model of IPF.
p-value: p=<0.05
Abstract Rationale IPF is an incurable lung disease, whereby irreversible fibrosis in the distal lung impairs lung function. Anti-fibrotics pirfenidone (PFD) and nintedanib (Nin) slow progression but are not well tolerated and cannot reverse established disease. The anti-fibrotic angiotensin type 2 receptor (AT2R), which is part of the renin angiotensin system, is a promising novel therapeutic target in IPF. Buloxibutid, also known as Compound 21 (C21), is an AT2R agonist in early clinical trials for IPF, having shown antifibrotic efficacy in a bleomycin mouse model1. The novel, highly selective AT2R agonist NAc has demonstrated efficacy in renal and cardiac models of fibrosis, but its effects in the lung are not known. Aims To compare C21 with the novel AT2R agonist NAc and the IPF drugs pirfenidone and nintedanib, using human precision cut lung slices (hPCLS). Methods Matched hPCLS from agarose-inflated lungs were left untreated or stimulated with fibrotic cocktail (FC = TGFβ1, TNFα, LPA, PDGF)2 ± C21 (10µM), NAc (10µM), PFD (500µM) or Nin (1µM) for 120h. FFPE tissue sections used to quantify AT2R expression with a fluorescent tagged ligand. Secreted ECM proteins were measured by ELISA in conditioned media (CM), collagen neo-epitopes were measured in the CM (Nordic Bioscience). Results FC significantly increased expression of AT2R compared to vehicle (p 0.0001, n = 12) and increased secretion of both procollagen 1α1 (ng/mL: vehicle 40±12; FC 209±28, n = 21, p 0.01, paired t-test) and fibronectin (μg/mL: vehicle 1.6±0.2; FC 4.4±0.3, n = 15, p 0.01). C21, NAc, and Nin, but not PFD, significantly reduced secretion of both matrix proteins (p 0.05, one-way ANOVA, n = 17, 14). FC significantly increased production of PRO-C1 and -C3, but reduced PRO-C6 and C3M. Both C21 and Nin significantly inhibited FC-induced PRO-C1, and C21 trended to decrease PRO-C3 (p = 0.065) - neither NAc or PFD affected either marker. Discussion Fibrogenesis can be modelled ex vivo in hPCLS using a cocktail of IPF-relevant mediators. C21 and NAc, at 50-fold lower concentrations than PFD, demonstrated superior efficacy to PFD and comparable efficacy to Nin. Future studies to establish reversal of fibrosis by AT2R agonists in hPCLS from IPF lung would address a major limitation of current therapy and further support clinical translation of this novel drug class for IPF.1Rathinasabapathy et al. (2018), Front Physiol, 9:1802Alsafadi et al. (2017), Am J Physiol Lung Cell Mol Physiol, 6:312 This abstract is funded by: None
Papagianis et al. (Fri,) conducted a other in Idiopathic Pulmonary Fibrosis. AT2R agonists (C21 and NAc) vs. Pirfenidone (500µM), nintedanib (1µM), and vehicle was evaluated on Secretion of procollagen 1α1 and fibronectin (p=<0.05). AT2R agonists C21 and NAc significantly reduced secretion of procollagen 1α1 and fibronectin in human precision cut lung slices stimulated with a fibrotic cocktail (p<0.05).