Pirfenidone exacerbates Th2-driven vasculopathy in a mouse model of systemic sclerosis-associated interstitial lung disease

Abstract

Systemic sclerosis (SSc) is an autoimmune disease characterised by severe vasculopathy and fibrosis of various organs including the lung. Targeted treatment options for SSc-associated interstitial lung disease (SSc-ILD) are scarce. Here we assessed the effects of pirfenidone in a mouse model of SSc-ILD.Pulmonary function, inflammation and collagen deposition in response to pirfenidone were assessed in Fra-2-overexpressing (Fra-2 TG) and bleomycin-treated mice. In Fra-2 TG mice, lung transcriptome was analysed after pirfenidone treatment. In vitro, pirfenidone effects on human eosinophil and endothelial cell function were analysed using flow cytometry-based assays and electric cell-substrate impedance measurements, respectively.Pirfenidone treatment attenuated pulmonary remodelling in the bleomycin-model, but aggravated pulmonary inflammation, fibrosis, and vascular remodelling in Fra-2 TG mice. Pirfenidone increased interleukin (IL)-4 levels and eosinophil numbers in lung tissue of Fra-2 TG mice without directly affecting eosinophil activation and migration in vitro. A pronounced immune response with high levels of cytokines/chemokines and disturbed endothelial integrity with low VE-cadherin levels were observed in pirfenidone-treated Fra-2 TG mice. In contrast, eosinophil, IL-4 and VE-cadherin levels were unchanged in bleomycin-treated mice and not influenced by pirfenidone. In vitro, pirfenidone exacerbated the IL-4 induced reduction of endothelial barrier resistance leading to higher leukocyte transmigration.This study shows that anti-fibrotic properties of pirfenidone may be overruled by unwanted interactions with pre-injured endothelium in a setting of high Th2 inflammation in a model of SSc-ILD. Careful ILD patient phenotyping may be required to exploit benefits of pirfenidone while avoiding therapy failure and additional lung damage in some patients.

Fra-2 Is a Dominant Negative Regulator of Natural Killer Cell Development

“…Although, several studies have investigated the immune profile in Fra-2 TG mice, none investigated the presence of NK cells ( 13 , 18 , 21 – 23 , 27 ). Consistent with previous studies we found increased numbers of eosinophils and T and B cells, but decreased alveolar macrophages ( 13 , 21 , 23 ).…”

Animal models in systemic sclerosis: an update

“…In the other hands, pirfenidone aggravated pulmonary inflammation, fibrosis, and vascular remodeling in Fra-2 tg mice. Increased IL-4 levels and eosinophil numbers of pronounced immune response and disrupted endothelial integrity was observed in pirfenidone-treated Fra-2 tg mice [45 ▪ ]. It remains to be seen whether these findings on the lack of efficacy of pirfenidone translate to human studies.…”

“…Nintedanib, an antifibrotic medicine approved for the treatment of SSc-ILD [43,44], ameliorates vascular remodeling, fibrosis, and endothelial cell apoptosis in the Fra-2 tg model. Another interesting study with both of Fra-2 tg mice and intratracheal bleomycin injected mice model study demonstrated that the antifibrotic drug Pirfenidone treatment aggravated pulmonary inflammation, fibrosis, and vascular remodeling in Fra-2 tg mice whereas attenuated bleomycin induced pulmonary remodeling [45 ▪ ]. Pirfenidone is an approved treatment option for IPF, but not for SSc-ILD.…”

The vascular perspective on acute and chronic lung disease

“…This model is characterized by progressive vascular remodeling, PF, chronic Th2 inflammation, and a concomitant decrease in regulatory T cells (Tregs) ( 62 , 96 , 97 ). Importantly, it was shown that Th2 cytokines, such as IL-4, predispose the ECs to exacerbated injury, leading to an aggravated disease phenotype following treatment with the antifibrotic drug pirfenidone in Fra-2–overexpressing mice, but not in bleomycin-treated mice ( 98 ). The clinical importance of restoring T cell homeostasis was also highlighted by treatments that improve vascular remodeling in this model, including the T cell costimulation blocker abatacept ( 99 ) and restoration of Tregs by either adoptive transfer or low-dose IL-2 treatment ( 100 ).…”