Pirfenidone: a novel antifibrotic agent with implications for the treatment of obliterative bronchiolitis

The anti-fibrotic agent pirfenidone synergizes with cisplatin in killing tumor cells and cancer-associated fibroblasts

Background

Anti-fibrotic drugs such as pirfenidone have been developed for the treatment of idiopathic pulmonary fibrosis. Because activated fibroblasts in inflammatory conditions have similar characteristics as cancer-associated fibroblasts (CAFs) and CAFs contribute actively to the malignant phenotype, we believe that anti-fibrotic drugs have the potential to be repurposed as anti-cancer drugs.

Methods

The effects of pirfenidone alone and in combination with cisplatin on human patient-derived CAF cell lines and non-small cell lung cancer (NSCLC) cell lines were examined. The impact on cell death in vitro as well as tumor growth in a mouse model was determined. Annexin V/PI staining and Western blot analysis were used to characterize cell death. Synergy was assessed with the combination index method using Calcusyn software.

Results

Pirfenidone alone induced apoptotic cell death in lung CAFs at a high concentration (1.5 mg/mL). However, co-culture in vitro experiments and co-implantation in vivo experiments showed that the combination of low doses of cisplatin (10 μM) and low doses of pirfenidone (0.5 mg/mL), in both CAFs and tumors, lead to increased cell death and decreased tumor progression, respectively. Furthermore, the combination of cisplatin and pirfenidone in NSCLC cells (A549 and H157 cells) leads to increased apoptosis and synergistic cell death.

Conclusions

Our studies reveal for the first time that the combination of cisplatin and pirfenidone is active in preclinical models of NSCLC and therefore may be a new therapeutic approach in this disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2162-z) contains supplementary material, which is available to authorized users.

Immunosuppression in lung transplantation

Lung transplantation can be a life-saving procedure for those with end-stage lung diseases. Unfortunately, long term graft and patient survival are limited by both acute and chronic allograft rejection, with a median survival of just over 6 years. Immunosuppressive regimens are employed to reduce the rate of rejection, and while protocols vary from center to center, conventional maintenance therapy consists of triple drug therapy with a calcineurin inhibitor (cyclosporine or tacrolimus), antiproliferative agents [azathioprine (AZA), mycophenolate, sirolimus (srl), everolimus (evl)], and corticosteroids (CS). Roughly 50% of lung transplant centers also utilize induction therapy, with polyclonal antibody preparations [equine or rabbit anti-thymocyte globulin (ATG)], interleukin 2 receptor antagonists (IL2RAs) (daclizumab or basiliximab), or alemtuzumab. This review summarizes these agents and the data surrounding their use in lung transplantation, as well as additional common and novel therapies in lung transplantation. Despite the progression of the management of lung transplant recipients, they continue to be at high risk of treatment-related complications, and poor graft and patient survival. Randomized clinical trials are needed to allow for the development of better agents, regimens and techniques to address above mentioned issues and reduce morbidity and mortality among lung transplant recipients.

In vitro effects of pirfenidone on cardiac fibroblasts: proliferation, myofibroblast differentiation, migration and cytokine secretion

Cardiac fibroblasts (CFs) are the primary cell type responsible for cardiac fibrosis during pathological myocardial remodeling. Several studies have illustrated that pirfenidone (5-methyl-1-phenyl-2-[1H]-pyridone) attenuates cardiac fibrosis in different animal models. However, the effects of pirfenidone on cardiac fibroblast behavior have not been examined. In this study, we investigated whether pirfenidone directly modulates cardiac fibroblast behavior that is important in myocardial remodeling such as proliferation, myofibroblast differentiation, migration and cytokine secretion. Fibroblasts were isolated from neonatal rat hearts and bioassays were performed to determine the effects of pirfenidone on fibroblast function. We demonstrated that treatment of CFs with pirfenidone resulted in decreased proliferation, and attenuated fibroblast α-smooth muscle actin expression and collagen contractility. Boyden chamber assay illustrated that pirfenidone inhibited fibroblast migration ability, probably by decreasing the ratio of matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1. Furthermore, pirfenidone attenuated the synthesis and secretion of transforming growth factor-β1 but elevated that of interleukin-10. These direct and pleiotropic effects of pirfenidone on cardiac fibroblasts point to its potential use in the treatment of adverse myocardial remodeling.

Novel systems biology insights using antifibrotic approaches for diabetic kidney disease

Although several interventions slow the progression of diabetic nephropathy, current therapies do not halt progression completely. Recent preclinical studies suggested that pirfenidone (PFD) prevents fibrosis in various diseases, but the mechanisms underlying its antifibrotic action are incompletely understood. To explore the therapeutic potential of PFD, we studied the PFD-treated db/db diabetic mouse kidney by liquid chromatography-tandem mass spectrometry proteomics. A total of 21 proteins unique to PFD-treated diabetic kidneys were identified. Analysis of gene ontology and protein-protein interactions of these proteins suggested that PFD may regulate RNA translation. Two key proteins involved in mRNA translation initiation and elongation were further evaluated and found to be regulated by PFD at the level of phosphorylation. In conclusion, insights from combining proteomics and bioinformatics improve the likelihood of rapid advancement of novel clinical therapies focused on reducing inflammation and fibrosis for diabetic complications.

Pirfenidone inhibits T-cell activation, proliferation, cytokine and chemokine production, and host alloresponses

BACKGROUND

We previously showed that pirfenidone, an anti-fibrotic agent, reduces lung allograft injury or rejection. In this study, we tested the hypothesis that pirfenidone has immune modulating activities and evaluated its effects on the function of T-cell subsets, which play important roles in allograft rejection.

METHOD

We first evaluated whether pirfenidone alters T-cell proliferation and cytokine release in response to T-cell receptor (TCR) activation, and whether pirfenidone alters regulatory T cells (CD4CD25) suppressive effects using an in vitro assay. Additionally, pirfenidone effects on alloantigen-induced T-cell proliferation in vivo were assessed by adoptive transfer of carboxyfluorescein diacetate succinimidyl ester-labeled T cells across a parent->F1 major histocompatibility complex mismatch, as well as using a murine heterotopic cardiac allograft model (BALB/c->C57BL/6).

RESULTS

Pirfenidone was found to inhibit the responder frequency of TCR-stimulated CD4 cell total proliferation in vitro and in vivo, whereas both CD4 and CD8 proliferation index were reduced by pirfenidone. Additionally, pirfenidone inhibited TCR-induced production of multiple pro-inflammatory cytokines and chemokines. Interestingly, there was no change on transforming growth factor-beta production by purified T cells, and pirfenidone had no effect on the suppressive properties of naturally occurring regulatory T cells. Pirfenidone alone showed a small but significant (P<0.05) effect on the in vivo allogeneic response, whereas the combination of pirfenidone and low dose rapamycin had more remarkable effect in reducing the alloantigen response with prolonged graft survival.

CONCLUSION

Pirfenidone may be an important new agent in transplantation, with particular relevance to combating chronic rejection by inhibiting both fibroproliferative and alloimmune responses.

Pirfenidone: a novel potential therapeutic agent in the management of chronic allograft rejection

Chronic allograft dysfunction is a leading cause of allograft failure, morbidity, and mortality after solid organ transplantation. The pathogenesis of chronic allograft failure has a final common pathway leading to organ fibrosis. Pirfenidone is an effective and novel antifibrotic agent with anti-inflammatory properties. Clinical use of the agent has been tested in a number of nontransplant recipients and has a favorable safety profile based on available clinical data. Building on these observations and findings, and considering the role of fibrosis in chronic allograft rejection, pirfenidone was initially investigated as adjunct therapy in a rat heterotopic tracheal transplantation model. This led to several studies confirming that pirfenidone may well be worth considering for further investigation. This paper reviews the possibility of using pirfenidone in clinical transplantation management.

Pirfenidone inhibits obliterative airway disease in mouse tracheal allografts

BACKGROUND

Obliterative bronchiolitis (OB) is the histologic correlate of chronic airway rejection, which remains the most significant cause of death in long-term survivors of lung transplantation. Using an established murine heterotopic tracheal transplant model of chronic airway rejection, the effects of the oral anti-fibrotic agent pirfenidone on development of the OB-like lesion were evaluated.

METHODS

Tracheas from BALB/c mice were implanted into the sub-cutaneous tissue of C57BL/6 mice, and the allografts were evaluated morphologically for airway rejection changes and immunohistochemically for transforming growth factor (TGF)-beta at 16 or 28 days after transplantation. In addition, the potential additive effects of pirfenidone in combination with 2 immunosuppressive agents, cyclosporine or rapamycin, was evaluated.

RESULTS

Compared with untreated controls, pirfenidone-fed mice showed less epithelial cell injury and luminal granulation tissue and fibrosis. Plasma TGF-beta levels and local TGF-beta expression based on immunohistochemistry were decreased in the pirfenidone-treated animals. Pirfenidone given on Day 9 or 16 post-transplant through Day 28 resulted in no significant improvement compared with controls. There was no significant additive effect of pirfenidone in combination with cyclosporine, whereas pirfenidone plus rapamycin demonstrated additive protection against the development of the obstructive airway lesion.

CONCLUSIONS

In aggregate, these results show that the anti-fibrotic agent pirfenidone inhibits the development of the OB-like lesion in this mouse model of human chronic airway rejection, and that these effects may be mediated by TGF-beta. The results also suggest that pirfenidone may be worthy of investigation in human lung transplant recipients at high risk of developing OB.

Pirfenidone: anti-fibrotic agent with a potential therapeutic role in the management of transplantation patients

Pirfenidone has a simple chemical structure, but may have profound implications for transplantation management. One of the leading causes of allograft failure is chronic allograft dysfunction, manifested by chronic inflammation and chronic fibrosis [Estenne, M., Hertz, M.I., 2002. Bronchiolitis obliterans after human lung transplantation. AJRCCM. 166, 440-444.]. This review summarizes the literature to date on Pirfenidone in the setting of transplantation, and those studies pertinent to the mechanisms of organ rejection and possible use of Pirfenidone in transplantation patients.

Emerging drugs for idiopathic pulmonary fibrosis

Pulmonary fibrosis is often the end stage of chronic, persistent, low-level lung injury, either of known or unknown cause. The most severe form of pulmonary fibrosis is idiopathic pulmonary fibrosis (IPF), a disease process of unknown aetiology and one that often leads to respiratory failure and death. At present there are no proven or effective drug therapies for IPF. Recent advances in understanding of disease pathogenesis have focused attention on drug targeting of fibrogenic pathways, as opposed to traditional anti-inflammatory approaches. In this report, the present status of drug development of a number of emerging antifibrotic strategies and agents that may prove more effective in the therapy of this progressive, debilitating and fatal disease are reviewed.

Idiopathic pulmonary fibrosis: emerging concepts on pharmacotherapy

Idiopathic pulmonary fibrosis (IPF) is a progressive, fibrosing disease of the distal air spaces of the lung of unknown aetiology. IPF is usually fatal with a median survival of < 3 years. There are currently no effective pharmacotherapeutic agents for the treatment of IPF. In this review, unifying concepts on the pathogenesis of IPF based on understanding of host responses to tissue injury are presented. These host responses involve tightly regulated and contextually orchestrated inflammatory and repair processes. Dysregulation of either of these processes can lead to pathological outcomes. Fibrosis results from an exaggerated or dysregulated repair process that proceeds 'uncontrolled' even after inflammatory responses have subsided. Disease heterogeneity may arise when inflammation and repair are in different (dys)regulatory phases, thus accounting for regional disparity. Usual interstitial pneumonia (UIP), the histopathological correlate of clinical IPF, represents a more fibrotic tissue reaction pattern and for which anti-inflammatory agents are ineffective. Emerging 'antifibrotic' drugs and strategies for UIP/IPF are discussed. The importance of accurately phenotyping a highly heterogeneous disease process that may require individualised and 'combined' therapies is emphasised.

Effect of Pirfenidone on Apoptosis-Regulatory Genes in Chronic Cyclosporine Nephrotoxicity

BACKGROUND

: Apoptosis was shown to play a role in the progression of fibrosis in a chronic cyclosporine A (CsA) nephrotoxicity animal model. In addition, the antifibrotic molecule pirfenidone (PFD) was shown to ameliorate fibrosis in this model. We evaluated the role of PFD on the expression of apoptosis-regulatory genes in the kidneys of CsA-treated rats.

METHODS

: Rats were administered CsA 7.5 mg/kg per day, CsA+PFD (250 mg/kg/day), vehicle (VH), or VH+PFD, and sacrificed at 28 days. Physiologic and histologic changes were studied, and apoptosis was detected by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling stain. The mRNA expression of pro-apoptotic genes p53 and Fas-ligand was evaluated by quantitative polymerase chain reaction, and that of Bcl-xL, an anti-apoptotic gene, was evaluated by Northern blot analysis. In addition to mRNA expression, immunohistochemical studies of caspase 3 were performed.

RESULT

: PFD administration to CsA-treated rats significantly ameliorated nephrotoxicity. Apoptosis-positive cells were increased by CsA but significantly reduced by PFD treatment (68+/-19 vs. 3+/-1, P<0.01). In addition, PFD down-regulated the mRNA expression of CsA-induced p53 and Fas-ligand (P<0.01) and increased that of Bcl-xL, previously reduced by CsA (P<0.01). Finally, PFD significantly down-regulated caspase 3 expression, present mostly on renal tubular epithelial cells. None of these changes were observed in VH-treated rats.

CONCLUSION

: Whereas CsA favored the expression of pro-apoptotic genes, that effect was ameliorated by PFD. Because apoptosis can partly explain the loss of cells associated with fibrosis, the influence of PFD on apoptosis-regulatory genes in a manner that reduces apoptosis may explain some of its antifibrotic properties.

Pirfenidone inhibits obliterative airway disease in a murine heterotopic tracheal transplant model

BACKGROUND

Chronic lung allograft rejection in the form of bronchiolitis obliterans syndrome and its histopathologic correlate, obliterative bronchiolitis (OB), are a major source of morbidity and mortality after lung transplantation. Murine heterotopic tracheal transplants into fully allogeneic mismatched recipients develop obliterative airway disease (OAD), which is a suitable model of OB. Using this murine heterotopic tracheal allograft model, we evaluated the effect of pirfenidone, a novel antifibrotic agent, on the development of OAD.

METHODS

Mice transplanted with complete MHC-mismatched tracheal allografts received pirfenidone (0.5%) in pulverized food according to different schedules: daily for the first 14 days after transplantation or daily for the duration of the study beginning on posttransplantation days 0, 5, or 10.

RESULTS

Mice on a continuous daily regimen of pirfenidone failed to develop evidence of chronic allograft rejection at the termination of the study (60 days). Mice receiving pirfenidone limited to the early posttransplantation period had delayed onset of OAD to 60 days. Forty percent (2/5) of mice receiving a continuous regimen of pirfenidone beginning on day 5 after transplantation had no evidence of OAD at 28 days. However, when the drug was started on day 10, all mice developed OAD by 28 days.

CONCLUSIONS

Our results demonstrate a delay of onset or abrogation of OAD when pirfenidone is administered in the early posttransplantation period. These findings suggest that pirfenidone is a candidate drug to be evaluated for prevention of the fibrotic changes seen in OB in human recipients of lung transplants.

Pirfenidone: A novel anti-fibrotic agent and progressive chronic allograft rejection

In our established model of heterotopic tracheal transplantation, at day 28 following transplantation, obliteration of the lumen is observed, which is histologically similar to that seen in Obliterative Bronchiolitis (OB). Pirfenidone (Pir) is a novel anti-fibrotic agent that causes no immunosuppression, but does downregulate the production of TGF-beta and collagen in vitro. We hypothesized that when used in this in vivo model, that Pir may alter the observed luminal fibrosis and obliteration.

METHODS

The treatment groups were: CSA, Pir and CSA, Pir only (n=6 each). Luminal supernatants and tissue were obtained from these groups at day 28. H&E staining was completed, as well as MTS proliferation assays, and TGF-beta ELISA on the fluids.

RESULTS

The CSA-Pir combined treatment group was the least fibrogenic in vitro (p<0.001). The TGF-beta levels were elevated in all groups (range 203-372 pg/ml). The H&E staining revealed that the luminal obliteration was less organized in the combined CSA-Pir group.

CONCLUSIONS

Our study shows that the combination of CSA-Pir results in a less fibrogenic luminal fluid and a less dense fibrous luminal plug. Pir should be further studied in obliterative airways disease (OAD).

Pirfenidone effectively reverses experimental liver fibrosis

BACKGROUND/AIMS

Our group has been involved in searching for different strategies to ameliorate hepatic cirrhosis. The aim of this study was to evaluate the effect of Pirfenidone in the reversion or prevention of cirrhosis experimentally induced in rats by chronic administration of CCl(4) and bile-duct ligation (BDL).

METHODS

Male cirrhotic Wistar rats (8 weeks of intoxication and then hepatotoxin was discontinued) received either oral saline or Pirfenidone at 500 mg/kg per day.

RESULTS

High levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase decreased significantly (P<0.001) in animals treated with Pirfenidone (n=11) with regard to saline-administrated animals (n=9). Prothrombin activity and bilirubins were also reduced. Computerized fibrosis index demonstrated a 70% decrease (P<0.001) along with less hydroxyproline content, reduction in activated HSC and higher active cell regeneration. A rearrangement of the parenchyma was also noted and gene expression of collagens I, III and IV, transforming growth factor beta-1, Smad-7, TIMP-1 and PAI-1 decreased considerably in treated animals. Cirrhotic rats in which CCl(4) was not discontinued displayed 40% liver fibrosis reduction. In a different cirrhosis model, 4-week BDL rats treated with the drug showed a significant 50% reduction in hepatic fibrosis (P<0.01).

CONCLUSIONS

This new drug might be useful in healing human disease.

Pharmacokinetics and metabolism of a novel antifibrotic drug pirfenidone, in mice following intravenous administration

The present study describes the pharmacokinetics and metabolism of pirfenidone (PD), a compound which has been shown to have significant antifibrotic effects in rodent models of pulmonary and cardiac fibrosis. Despite the fact that this compound is currently in phase II clinical trials, little data are available on the metabolism and disposition of this agent in rodents or humans. Radioactive PD [benzene ring (14)C(U)] was administered i.v. to mice at 40 mg PD/kg body weight, and animals were killed at varying times for determination of parent compound and metabolites in various tissues. The disappearance of parent compound from the plasma followed apparent 2-compartment elimination kinetics with a terminal elimination half-life of 8.6 min. Cl (0.10 ml/min/g) and V(d(ss)) (0.67 ml/g) indicated that PD was rapidly distributed in body water. This is consistent with the finding that peak tissue radioactivity occurred within 5 min following the i.v. administration of [(14)C]-PD and that well-perfused tissues, kidney>liver>lung have much higher levels of parent compound and metabolites than did fat. Two peaks isolated from plasma samples by HPLC yielded mass spectra that were consistent with initial oxidation to the alcohol followed by further metabolism to the carboxylic acid. The radioactivity recovered in the 24 h urine samples averaged 97% of the administered dose and none of that was associated with the parent compound. The short plasma half-life of parent compound in mice supports the need for additional studies in humans where the compound has been shown to have clinical benefits.

Pirfenidone inhibits early myointimal proliferation but has no effect on late lesion size in rats

AIMS

intimal hyperplasia is mediated by smooth muscle cell proliferation, migration and deposition of extracellular matrix. The anti-fibrotic agent pirfenidone has been shown to inhibit pro-fibrotic growth factors in non-vascular inflammatory models. This study investigated the effect of the novel anti-fibrotic agent pirfenidone on the development of neointima.

METHODS

male Sprague-Dawley rats received either standard diet or diet supplemented with pirfenidone (250, 500, 1000 mg/kg/day). Animals underwent left common carotid balloon angioplasty and were explanted at 4, 8, 14 and 28 days and analysed for intimal thickening, pro-fibrotic gene expression, extracellular matrix deposition and metalloproteinase activity.

RESULTS

neointimal thickness was significantly reduced in a dose-dependent manner at 14 days; pirfenidone 250 mg/kg (p<0.005), pirfenidone 500 mg/kg (p<0.001), pirfenidone 1 g/kg ( p<0.001). There were no significant differences in intimal thickening at 28 days. Expression of MMP-2, MMP-9, TIMP-1, collagen III and TGF-beta were all significantly inhibited at 14 days. Both collagen III expression and ECM deposition were reduced at 28 days ( p<0.05 and <0.002 respectively).

CONCLUSION

pirfenidone reduces expression of MMPs governing smooth muscle cell proliferation and migration (MMP-2 and 9), and genes favouring ECM accumulation (TIMP-1 and collagen III). This study shows that inhibition of MMP activity is not sufficient to inhibit late lesion size.

Pirfenidone treatment decreases transforming growth factor-beta1 and matrix proteins and ameliorates fibrosis in chronic cyclosporine nephrotoxicity

Chronic cyclosporine (CsA) nephrotoxicity is characterized by tubulointerstitial fibrosis. Pirfenidone (PFD) is a novel antifibrotic compound that was shown to prevent and even reverse fibrosis. The mechanism of action of PFD is unclear but involves inhibition of transforming growth factor-beta (TGF-beta). Salt-depleted rats were administered CsA, CsA + PFD, vehicle (VH) or VH + PFD and sacrificed at 28days. Physiologic and histologic changes were studied in addition to TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and biglycan mRNA expressions by Northern blot. TGF-beta1 immunohistochemistry was also performed. Treatment with PFD ameliorated CsA-induced fibrosis by about 50% (p < 0.05). CsA-induced decrease in creatinine clearance improved with PFD but the difference was not significant. TGF-beta1, PAI-1 and biglycan mRNA expressions increased with CsA (p < 0.05 vs. VH) but strikingly improved with PFD treatment (p < 0.05 vs. CsA), which brought the levels down to VH levels. PFD treatment also decreased TGF-beta1 protein expression by 80%. These results demonstrate that PFD can attenuate renal fibrosis in this model. PFD was associated with a decrease in TGF-beta1 expression, which, in turn, was associated with a decrease in matrix deposition. These experiments suggest that PFD can be clinically useful for preventing chronic CsA nephrotoxicity and may prove to be helpful in other progressive renal diseases.