Pirfenidone inhibits dimethylnitrosamine-induced hepatic fibrosis in rats

Vitamin A-modified ZIF-8 lipid nanoparticles for the therapy of liver fibrosis

Liver fibrosis (LF) is one of the major diseases that threaten human health. Until now, no effective drugs have been approved for clinical anti-liver fibrosis treatment. In this study, zeolitic imidazolate framework-8 (ZIF-8) lipid nanoparticles loaded with pirfenidone (PFD) and modified with vitamin A (VA) were constructed (VA-PFD@ZIF-8@DMPC NPs). PFD was embedded in ZIF-8 by the "one-pot" method, and the prepared ZIF-8 had a small particle size (84.3 nm) and high drug loading (54.46%). Moreover, the inherent pH sensitivity of ZIF-8 makes it stable in a normal physiological environment and collapsed in an acidic environment, thus controlling drug release and preventing drug leakage. Besides, the phospholipid layer makes the nano-drug delivery system dispersible and improves its biocompatibility. More importantly, VA is modified on the surface of nanoparticles (NPs), which can target the highly expressed retinol-binding protein receptor (RBPR) on the surface of hepatic stellate cells (HSCs), thereby accurately increasing the local drug concentration at the site of LF. In vivo experiments showed that VA-PFD@ZIF-8@DMPC NPs can reduce liver injury, improve the degree of LF, and exert specific therapeutic effects on LF. In conclusion, this nano-delivery system may become a novel and effective anti-liver fibrosis treatment.

Increased Fibrosis in White Adipose Tissue of Male and Female bGH Transgenic Mice Appears Independent of TGF-β Action

Fibrosis is a pathological state caused by excess deposition of extracellular matrix proteins in a tissue. Male bovine growth hormone (bGH) transgenic mice experience metabolic dysfunction with a marked decrease in lifespan and with increased fibrosis in several tissues including white adipose tissue (WAT), which is more pronounced in the subcutaneous (Sc) depot. The current study expanded on these initial findings to evaluate WAT fibrosis in female bGH mice and the role of transforming growth factor (TGF)-β in the development of WAT fibrosis. Our findings established that female bGH mice, like males, experience a depot-dependent increase in WAT fibrosis, and bGH mice of both sexes have elevated circulating levels of several markers of collagen turnover. Using various methods, TGF-β signaling was found unchanged or decreased-as opposed to an expected increase-despite the marked fibrosis in WAT of bGH mice. However, acute GH treatments in vivo, in vitro, or ex vivo did elicit a modest increase in TGF-β signaling in some experimental systems. Finally, single nucleus RNA sequencing confirmed no perturbation in TGF-β or its receptor gene expression in any WAT cell subpopulations of Sc bGH WAT; however, a striking increase in B lymphocyte infiltration in bGH WAT was observed. Overall, these data suggest that bGH WAT fibrosis is independent of the action of TGF-β and reveals an intriguing shift in immune cells in bGH WAT that should be further explored considering the increasing importance of B cell-mediated WAT fibrosis and pathology.

A new approach based on CXCR4-targeted combination liposomes for the treatment of liver fibrosis

Liver fibrosis results from excessive extracellular matrix accumulation due to injury and leads to cirrhosis, cancer, and death. Herein, we propose a chemokine receptor 4 (CXCR4)-targeted combination (CTC) liposomal therapy to treat carbon tetrachloride (CCl₄)-induced liver fibrosis in a mouse model. This study aims to combine small molecules such as pirfenidone and AMD3100 in a single nanoplatform to investigate their synergistic antifibrotic effects in a setting of CCl₄-induced liver fibrosis. CTC liposomes (CTC lipo) were prepared using the thin-film hydration method. CTC lipo exhibited a spherical shape, and the particle size was recorded at the nanoscale which confirms its appropriateness for in vitro and in vivo applications. CTC lipo had good storage and serum stability. The entrapped drugs in CTC lipo showed reduced toxicity at higher concentrations. CTC lipo displayed CXCR4 mediated cell uptake and were internalized by caveolae-mediated endocytosis. CTC lipo showed CXCR4 targeting and stromal cell-derived factor 1α (SDF1-α)/CXCR4 axis blocking activity. CTC lipo reduced the elevated serum aspartate aminotransferase (AST), alanine transaminase (ALT), and hydroxyproline (HYP) levels. The histological studies showed improved liver architecture and reduced collagen deposition after treatment. Transforming growth factor β (TGFβ), alpha-smooth muscle actin (α-SMA), and collagen I were elevated by CCl₄ in comparison with the Sham. Upon CTC liposomal treatment, the quantitative score for the elevated fibrotic proteins such as TGFβ, α-SMA, and collagen I was normalized. CTC lipo displayed significant downregulation of the upregulated TGFβ, α-SMA, collagen I, and P-p38 expressions at the molecular level. The CXCR4 targeted liposomes showed prolonged biodistribution at 24 h. Our findings indicated that CTC lipo might be an alternative antifibrotic therapy that may offer new access to research and development. In a nutshell, the present study suggests that systemic administration of CTC lipo has efficient antifibrotic potential and deserves to be investigated for further clinical applications.

Pirfenidone attenuates acetaminophen-induced liver injury via suppressing c-Jun N-terminal kinase phosphorylation

Acetaminophen (APAP)-induced liver injury is the most frequent cause of acute liver failure in Western countries. Pirfenidone (PFD), an orally bioavailable pyridone derivative, is clinically used for idiopathic pulmonary fibrosis treatment and has antifibrotic, anti-inflammatory, and antioxidant effects. Here we examined the PFD effect on APAP-induced liver injury. In a murine model, APAP caused serum alanine aminotransferase elevation attenuated by PFD treatment. We performed terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) and vital propidium iodide (PI) stainings simultaneously. APAP induced TUNEL-positive/PI-negative necrosis around the central vein and subsequent TUNEL-negative/PI-positive oncotic necrosis with hemorrhage and caused the upregulation of hypercoagulation- and hypoxia-associated gene expressions. PFD treatment suppressed these findings. Western blotting revealed PFD suppressed APAP-induced c-Jun N-terminal kinase (JNK) phosphorylation despite no effect on JNK phosphatase expressions. In conclusion, simultaneous TUNEL and vital PI staining is useful for discriminating APAP-induced necrosis from typical oncotic necrosis. Our results indicated that PFD attenuated APAP-induced liver injury by suppressing TUNEL-positive necrosis by directly blocking JNK phosphorylation. PFD is promising as a new option to prevent APAP-induced liver injury.

The anti-fibrotic drug pirfenidone inhibits liver fibrosis by targeting the small oxidoreductase glutaredoxin-1

Activation of the hepatic stellate cells (HSCs) is a key pathogenic event in liver fibrosis. Protein S-glutathionylation (PSSG) of cysteine residues is a distinct form of oxidative response that modifies protein structures and functions. Glutaredoxin-1 (GLRX) reverses PSSG by liberating glutathione (GSH). In this study, we showed that pirfenidone (PFD), an anti-lung fibrosis drug, inhibited HSC activation and liver fibrosis in a GLRX-dependent manner. Glrx depletion exacerbated liver fibrosis, and decreased GLRX and increased PSSG were observed in fibrotic mouse and human livers. In contrast, overexpression of GLRX inhibited PSSG and liver fibrosis. Mechanistically, the inhibition of HSC activation by GLRX may have been accounted for by deglutathionylation of Smad3, which inhibits Smad3 phosphorylation, leading to the suppression of fibrogenic gene expression. Our results have established GLRX as the therapeutic target of PFD and uncovered an important role of PSSG in liver fibrosis. GLRX/PSSG can be both a biomarker and a therapeutic target for liver fibrosis.

Case Report: Efficacy of Ninjin'yoeito Treatment for Idiopathic Pulmonary Fibrosis

Ninjin'yoeito, a Kampo prescription, was administered to two patients with idiopathic pulmonary fibrosis (IPF) over a period of 12 weeks to improve loss of appetite and lassitude. In Case 1, improvements were observed in appetite, lassitude, and breathlessness, as well as increases or increasing tendencies in body weight, blood albumin level, and hemoglobin (Hb) level. Case 2 showed no changes in appetite but improvements in lassitude and no deterioration of breathlessness. His body weight and his blood albumin and Hb levels increased or showed increasing trends. In both cases, a trend for improvement of respiratory function was observed. In summary, ninjin'yoeito trended to improve the subjective symptoms and nutritional status of a patient with pulmonary fibrosis.

Protective role of pirfenidone against experimentally-induced pancreatitis

BACKGROUND

Pirfenidone (PFD) is an orally active antifibrotic agent that has anti-inflammatory activity in diverse animal models. Its effect against acute pancreatitis (AP) has not been elucidated. Hence, the present investigation was carried out to assess the potential protective role of PFD against l-arginine-induced AP in mice.

METHODS

AP was induced in adult male Swiss albino mice via intraperitoneal injections of l-arginine (4 g/kg, twice each 1 h apart). PFD (250 mg/kg, orally) was administered one day before and on the day of l-arginine challenge. Twenty-four hours after l-arginine injection, the severity of AP was evaluated using biochemical and histological analyses. Indices of oxidative stress, inflammation and apoptosis were evaluated using ELISA and immunohistochemistry (IHC).

RESULTS

PFD suppressed the development of l-arginine-induced AP as revealed by the improvement of histopathological lesions of pancreatic specimen and the significant reduction of serum amylase and lipase levels. Notably, PFD reduced the lipid peroxidation and enhanced the antioxidants such as reduced glutathione (GSH) and superoxide dismutase (SOD) in pancreatic tissue. Importantly, PFD suppressed AP-associated elevation of inflammatory cytokines along with depression of nuclear factor kappa-B (NF-κB) immuno-expression in pancreatic tissue. Lastly, PFD efficiently ameliorated AP-induced elevation of the pro-apoptotic protein (Bax) and increased AP-induced reduction of the anti-apoptotic protein (Bcl2).

CONCLUSIONS

PFD protected against l-arginine-induced AP in mice through anti-oxidative, anti-inflammatory and anti-apoptotic properties.

Synthesis and photophysical properties of deuteration of pirfenidone

In order to improve the metabolism of pirfenidone (5-methyl-1-phenylpyridin-2-one, PFD), the methyl-deuterated version of pirfenidone via the substitution of hydrogen (H) at C-5 by its isotope deuterium (D, 5D-PFD) was synthesized and its photophysical properties were investigated. The negative solvatochrom was observed in absorption and fluorescence spectra with increasing solvent polarity, which implied that intermolecular charge transfer (ICT) involved n → π* transition for both of PFD and 5D-PFD. The ground state and excited state dipole moment was calculated as 5.30 D and 3.30 D for PFD, and 3.70 D and 2.18 D for 5D-PFD, respectively, which suggested the more polar nature of PFD in the ground state than that of excited state compared with 5D-PFD. Density functional theory (DFT) results demonstrated a significant propensity of ICT from the electron-donor, methyl and carbonyl group to the amine group as an electron donor. The binding of metal ions with PFD or 5D-PFD induced a red-shift of π → π* transition and blue-shift of n → π* transition, respectively, indicating that the pyridone ring showed more stability upon binding of unoccupied orbital of metal ions with lone-pair electron of oxygen atom and thus prompted the electronic distribution on phenyl unit. Upon addition of metal ions, the aromatic region presented the characteristic upfield shifts, and the resonance contributed by 3-H showed a significant downfield chemical shift/deshielding effect, indicating the deduced resonance of 3-H and the improved electron distribution of phenyl unit. The binding and docking of human serum albumin showed that the affinity of 5D-PFD with HSA was lower than that of PFD, and also 5D-PFD might prefer to present free forms in the blood with better efficacy comparing with PFD. The pharmacokinetic of half-time (T_1/2) for oral and i.v. administration of 5D-PFD was found around 19 and 30 min, higher than that of i.v. administration of PFD, 8.6 min, reported by Giri et al. The results of this work suggest that the deuteration enhances the metabolism of PFD significantly with little change of physical-chemical property.

Effects of pirfenidone in acute and sub-chronic liver fibrosis, and an initiation-promotion cancer model in the mouse

Liver fibrosis results from chronic tissue damage and excessive regeneration with accumulation of extracellular matrix proteins; it is a precursor of liver cirrhosis and hepatocellular carcinoma. Liver fibrosis treatments are primarily directed at inflammation, with few options to combat fibrogenesis. Pirfenidone is a drug approved for idiopathic pulmonary fibrosis and this study was focused on anti-fibrotic and anti-cancer potential of pirfenidone in the liver of male B6C3F1/J mice. In a dose-finding study, mice were treated with CCl₄ (0.2ml/kg ip, 2×wk for 4weeks) while on a pirfenidone-containing (0-600mg/kg) diet. Pirfenidone at doses of 300 and 600mg/kg had significant anti-fibrotic (collagen) and anti-inflammatory (serum transaminases and "ballooning" hepatocyte) effects. In a sub-chronic study (14weeks), mice received CCl₄ while on pirfenidone (300mg/kg) diet. Pirfenidone significantly reduced collagen deposition, but had little effect of inflammation and injury. In an initiation-promotion cancer study with N-nitrosodiethylamine and CCl₄, pirfenidone (300mg/kg) did not affect incidence, size, or multiplicity of liver tumors. Overall, we conclude that while pirfenidone exhibits strong anti-fibrotic effects in early stage liver fibrosis, it is less effective in advanced liver fibrosis and was not protective in an initiation-promotion liver cancer.

Antifibrotic effect of pirfenidone in a mouse model of human nonalcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by steatosis with lobular inflammation and hepatocyte injury. Pirfenidone (PFD) is an orally bioavailable pyridone derivative that has been clinically used for the treatment of idiopathic pulmonary fibrosis. However, it remains unknown whether PFD improves liver fibrosis in a mouse model with human NASH-like phenotypes. In this study, we employed melanocortin 4 receptor-deficient (MC4R-KO) mice as a mouse model with human NASH-like phenotypes to elucidate the effect and action mechanisms of PFD on the development of NASH. PFD markedly attenuated liver fibrosis in western diet (WD)-fed MC4R-KO mice without affecting metabolic profiles or steatosis. PFD prevented liver injury and fibrosis associated with decreased apoptosis of liver cells in WD-fed MC4R-KO mice. Pretreatment of PFD inhibited the tumor necrosis factor-α (TNF-α)-induced liver injury and fibrogenic responses associated with decreased apoptosis of liver cells in wild-type mice. PFD also prevented TNF-α-induced hepatocyte apoptosis in vitro with reduced activation of caspase-8 and -3. This study provides evidence for the antifibrotic effect of PFD in a mouse model of human NASH. The data of this study highlight hepatocyte apoptosis as a potential therapeutic target, and suggest that PFD can be repositioned as an antifibrotic drug for human NASH.

Pirfenidone exerts a suppressive effect on CCL18 expression in U937-derived macrophages partly by inhibiting STAT6 phosphorylation

CONTEXT

CC chemokine ligand 18 (CCL18) is suggested to play a role in the development of pulmonary fibrosis. Macrophages are thought to be the main source of CCL18, and the effect of pirfenidone, an anti-fibrotic agent for idiopathic pulmonary fibrosis, on the expression of CCL18 in macrophages warrants investigation.

OBJECTIVE

The purpose of this study was to investigate the effect of pirfenidone on the expression of CCL18 in macrophages.

MATERIALS AND METHODS

U937 cells were differentiated into macrophages by phorbol myristate acetate and then stimulated with recombinant IL-4 to induce the production of CCL18. The cells were treated with pirfenidone, and the mRNA and protein levels for CCL18 were measured by a reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The effects of pirfenidone on the IL-4 receptor (IL-4R) expression and STAT6 activation were investigated and on the JAK kinase activity were measured using the Z'-LYTE™ kinase assay.

RESULTS

Pirfenidone significantly suppressed the expression of CCL18 when the cells were treated with concentrations of 50-250 μg/mL. Pirfenidone did not affect the expression of the IL-4R components. The selective STAT6 inhibitor AS1517499 suppressed CCL18 expression. Both AS1517499 and pirfenidone suppressed STAT6 phosphorylation (p < .05), although the effect of pirfenidone was less marked than that of AS1517499. The Z'-LYTE™ kinase assay showed a reduction in the activities of JAK1, JAK3 and TYK2 by pirfenidone.

CONCLUSION

Pirfenidone suppresses CCL18 expression in macrophages and this effect is thought to be attributed partly to the inhibition of STAT6 phosphorylation.

Hepatoprotective and Anti-fibrotic Agents: It's Time to Take the Next Step

Hepatic fibrosis and cirrhosis cause strong human suffering and necessitate a monetary burden worldwide. Therefore, there is an urgent need for the development of therapies. Pre-clinical animal models are indispensable in the drug discovery and development of new anti-fibrotic compounds and are immensely valuable for understanding and proofing the mode of their proposed action. In fibrosis research, inbreed mice and rats are by far the most used species for testing drug efficacy. During the last decades, several hundred or even a thousand different drugs that reproducibly evolve beneficial effects on liver health in respective disease models were identified. However, there are only a few compounds (e.g., GR-MD-02, GM-CT-01) that were translated from bench to bedside. In contrast, the large number of drugs successfully tested in animal studies is repeatedly tested over and over engender findings with similar or identical outcome. This circumstance undermines the 3R (Replacement, Refinement, Reduction) principle of Russell and Burch that was introduced to minimize the suffering of laboratory animals. This ethical framework, however, represents the basis of the new animal welfare regulations in the member states of the European Union. Consequently, the legal authorities in the different countries are halted to foreclose testing of drugs in animals that were successfully tested before. This review provides a synopsis on anti-fibrotic compounds that were tested in classical rodent models. Their mode of action, potential sources and the observed beneficial effects on liver health are discussed. This review attempts to provide a reference compilation for all those involved in the testing of drugs or in the design of new clinical trials targeting hepatic fibrosis.

Antifibrotic effect of pirfenidone on human pterygium fibroblasts

OBJECTIVE

The effects of pirfenidone were investigated on cultured human pterygium fibroblasts (HPFs).

METHODS

HPFs were obtained from pterygium surgery and subjected to primary culture. After treatment with 0.5, 1.0 or 1.5 mg/mL pirfenidone, MTT and cell migration assays were performed, and procollagen secretion and TGF-β expression were measured by Western blotting and immunofluorescence analysis.

RESULTS

Pirfenidone had a significant inhibitory effect on HPF proliferation, migration and collagen synthesis. There were no differences between the cells treated with 0.5, 1.0 and 1.5 mg/mL pirfenidone and the controls in the MTT assay. After 48 h of treatment with 1.0 or 1.5 mg/mL pirfenidone, TGF-β expression was significantly decreased.

CONCLUSIONS

These findings demonstrate that pirfenidone inhibits the proliferation, migration and procollagen secretion of HPFs at nontoxic concentrations by decreasing TGF-β expression. Thus, pirfenidone may be considered as a safe adjuvant for pterygium surgery to prevent recurrence.

Single- and Multiple-Dose Pharmacokinetics of Pirfenidone, an Antifibrotic Agent, in Healthy Chinese Volunteers

A randomized, dose-escalating study evaluated the pharmacokinetics of single and multiple oral doses of pirfenidone, a promising antifibrotic agent, in 48 healthy Chinese volunteers. The effects of sex and food on the pharmacokinetics of pirfenidone were also evaluated. Pharmacokinetics was determined from serial blood samples obtained up to 12 hours after administration of single 200-, 400-, or 600-mg doses of pirfenidone and after multiple doses of 400 mg administrated 3 times daily (tid). Plasma levels of pirfenidone and areas under the curve were found to be proportional to dose. Pirfenidone was rapidly absorbed (t(max) = 0.33-1 hours) and cleared (t((1/2)) = 2-2.5 hours). Pharmacokinetic parameters after multiple doses were similar to those after single doses. Food had a significant effect (P < .01) on the extent of absorption (AUC(0-infinity) = 37.4 +/- 15.4 mg x h/L [fed] vs 46.6 +/- 16.8 mg x h/L [fasted]), rate of absorption was considerably (P < .001) prolonged (t(max) = 1.5 +/- 0.4 hours [fed] vs 0.7 +/- 0.2 hours [fasted]), and peak concentrations were significantly (P < .001) decreased (C(max) = 9.2 +/- 2.9 mg/L [fed] vs 13.0 +/- 1.8 mg/L [fasted]). No significant sex differences were noted for pharmacokinetic variables. Pirfenidone was well tolerated. These results support a tid regimen of pirfenidone for the management of idiopathic pulmonary fibrosis. Concomitant intake of food will reduce the rate and extent (about 20%) of absorption, which is associated with better tolerability of pirfenidone.

Anchoring hepatic gene expression with development of fibrosis and neoplasia in a toxicant-induced fish model of liver injury

Fish have been used as laboratory models to study hepatic development and carcinogenesis but not for pathogenesis of hepatic fibrosis. In this study, a dimethylnitrosamine-induced fish model of hepatic injury was developed in Japanese medaka (Oryzias latipes) and gene expression was anchored with the development of hepatic fibrosis and neoplasia. Exposed livers exhibited mild hepatocellular degenerative changes 2 weeks' postexposure. Within 6 weeks, hepatic fibrosis/cirrhosis was evident with development of neoplasia by 10 weeks. Stellate cell activation and development of fibrosis was associated with upregulation of transforming growth factor beta 1 (tgfb1), tgfb receptor 2, mothers against decapentaplegic homolog 3 (smad3a), smad3b, beta-catenin (ctnnb1), myc, matrix metalloproteinase (mmp2), mmp14a, mmp14b, tissue inhibitors of metalloproteinase (timp) 2a, timp2b, timp3, collagen type I alpha 1a (col1a1a), and col1a1b and a less pronounced increase in mmp13 and col4a1 expression. Tgfb receptor I expression was unchanged. Immunohistochemistry suggested that biliary epithelial cells and stellate cells were the main producers of TGF-β1. This study identified a group of candidate genes likely to be involved in the development of hepatic fibrosis and demonstrated that the TGF-β pathway likely plays a major role in the pathogenesis. These results support the medaka as a viable fish model of hepatic fibrosis.

Pirfenidone restricts Th2 differentiation in vitro and limits Th2 response in experimental liver fibrosis

Polarized T helper type 2 (Th2) response is linked with fibrosis. Here, we evaluated the effect of the anti-fibrotic agent pirfenidone on Th type 1 (Th1) and Th2 responses. For in vivo testing; Wistar rats were made cirrhotic by intraperitoneal administration of thioacetamide. Once hepatic damage was established, pirfenidone was administered intragastrically on a daily basis during three weeks. Gene expression of Th marks was evaluated by RT-PCR and Western blot assays from liver homogenates. Pirfenidone therapy induced down-regulation of Th2 transcripts and proteins (GATA3 and IL-4), without affecting significantly Th1 genes expression (T-bet and IFN-γ). We found that the activated form of p38 MAPK (identified by Western blot) was reduced by pirfenidone treatment, which is consistent with the anti-Th2 activity observed. Pirfenidone reduced GATA3 nuclear localization without modifying its DNA binding activity (evaluated by electrophoretic mobility shift assay). For in vitro testing; human naive CD4+ T cells were cultured in either Th1 or Th2 polarizing conditions in the presence of pirfenidone and flow cytometric analysis of intracellular synthesis of IFN-γ and IL-4 was conducted. Pirfenidone impaired development of Th2 subpopulation. In conclusion, pirfenidone is capable of impairing Th2 differentiation and limits Th2 profibrogenic response. The mechanism involves p38 inhibition and regulation of GATA3 expression and translocation.

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.

The antifibrotic agent pirfenidone inhibits angiotensin II-induced cardiac hypertrophy in mice

Pirfenidone (5-methyl-1-phenyl-2-[(1)H]-pyridone) is an effective drug for idiopathic interstitial pneumonia that can prevent and reverse tissue fibrosis in several organs. Therefore, we investigated whether pirfenidone has a potential role in preventing angiotensin II (Ang II)-induced cardiac hypertrophy. A cardiac hypertrophic mouse model was created using an Ang II infusion (200 ng kg(-1) min(-1)) in wild-type mice for 2 weeks. Mice were divided into the following three groups: a saline-infused (control) group, an Ang II infusion (vehicle) group and an Ang II infusion+pirfenidone-treated (PFD) group, which received pirfenidone (300 mg kg(-1) per day) by gastric gavage during the Ang II infusion. At 2 weeks, we assessed hemodynamics and cardiac function and investigated tissue fibrosis of the myocardium histologically and genetically. Blood pressure in the vehicle group was significantly increased compared to the control group. Although blood pressure was not different between the vehicle and PFD groups, heart weight was significantly decreased in the PFD group. Echocardiography revealed that left ventricular hypertrophy was significantly increased in the vehicle group vs. the control group. Interestingly, pirfenidone significantly inhibited this effect. Continuous infusion of Ang II increased the perivascular and interstitial tissue fibrosis, and pirfenidone inhibited these fibrotic changes. Pirfenidone also inhibited Ang II-induced hypertrophy. In the vehicle group, the mRNA expressions of atrial natriuretic peptide, brain natriuretic peptide and transforming growth factor-β1 were increased, which was significantly inhibited by pirfenidone. Furthermore, the expression of mineralocorticoid receptors was attenuated by pirfenidone. These results indicate that pirfenidone might be effective as an antifibrotic drug in the treatment of cardiac hypertrophy induced by hypertension.

Role of chymase in the pathogenesis of experimental liver fibrosis in rats

AIM: To investigate the role of chymase in the pathogenesis of dimethylnitrosamine (DMN)-induced liver fibrosis in rats.

METHODS: Thirty male Wistar rats were randomly divided into three groups. The model group was administered with 10% DMN. The interventional group was given soybean trypsin inhibitor (SBTI) after induction of liver fibrosis with DMN. The normal group was given normal sodium. Liver histological and ultramicroscopic changes were observed, and serum indices for liver fibrosis, serum transforming growth factor β1 (TGF-β1) and hepatic chymase-like activity were measured at the end of the experiment.

RESULTS: Compared to the model group, the interventional group had narrower fiber separation and showed no typical pseudo-lobule. Transmission electron microscopy demonstrated that hepatic cell damage in the interventional group was lessened significantly as compared to that in the model group, and only scattered collagen fiber was observed in the sinus hepaticus. Serum levels of HA, LN, PC III, C IV, TGF-β1 and hepatic chymase-like activity in the interventional group were significantly lower than those in the model group (all P < 0.05).

CONCLUSION: Chymase participates in the development of liver fibrosis possibly by direct or indirect induction of TGF-β1 and may be a promising therapy target for hepatic fibrosis.

Influence of N-acetylcysteine against dimethylnitrosamine induced hepatotoxicity in rats

This study evaluates the hepatoprotective and antioxidant properties of N-acetylcysteine (NAC) on dimethylnitrosamine (DMN) induced hepatotoxicity in male Wistar albino rats. A single intraperitoneal dose of DMN (5 mg/kg b.w.) caused a significant increase in the levels of the serum marker enzymes (aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), glutamyl transpeptidase (γ-GT)) and a subsequent decrease in AST, ALT, ALP and increase in LDH and γ-GT in the liver tissue indicating hepatocellular damage. Elevation in the status of lipid peroxidation, fall in the activities of the enzymic (superoxide dismutase, catalase) and non-enzymic antioxidants (vitamin C, vitamin E) in the liver tissue further confirms oxidative stress and hepatocellular damage induced on DMN administration. Oral administration of NAC (50 mg/kg b.w.) for 7 days significantly prevented the above alterations in the status of the marker enzymes of hepatotoxicity and antioxidant parameters and restored them towards normalcy, which was further substantiated by the histopathological studies of the liver tissue. These results suggest that NAC offers hepatoprotection by ameliorating DMN-induced oxidative stress and hepatotoxicity and this protective effect was attributed to its antioxidant and free radical scavenging properties.

Pirfenidone for diabetic nephropathy

Pirfenidone is an oral antifibrotic agent that benefits diabetic nephropathy in animal models, but whether it is effective for human diabetic nephropathy is unknown. We conducted a randomized, double-blind, placebo-controlled study in 77 subjects with diabetic nephropathy who had elevated albuminuria and reduced estimated GFR (eGFR) (20 to 75 ml/min per 1.73 m²). The prespecified primary outcome was a change in eGFR after 1 year of therapy. We randomly assigned 26 subjects to placebo, 26 to pirfenidone at 1200 mg/d, and 25 to pirfenidone at 2400 mg/d. Among the 52 subjects who completed the study, the mean eGFR increased in the pirfenidone 1200-mg/d group (+3.3 ± 8.5 ml/min per 1.73 m²) whereas the mean eGFR decreased in the placebo group (-2.2 ± 4.8 ml/min per 1.73 m²; P = 0.026 versus pirfenidone at 1200 mg/d). The dropout rate was high (11 of 25) in the pirfenidone 2400-mg/d group, and the change in eGFR was not significantly different from placebo (-1.9 ± 6.7 ml/min per 1.73 m²). Of the 77 subjects, 4 initiated hemodialysis in the placebo group, 1 in the pirfenidone 2400-mg/d group, and none in the pirfenidone 1200-mg/d group during the study (P = 0.25). Baseline levels of plasma biomarkers of inflammation and fibrosis significantly correlated with baseline eGFR but did not predict response to therapy. In conclusion, these results suggest that pirfenidone is a promising agent for individuals with overt diabetic nephropathy.

Pirfenidone treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a discrete clinicopathologic entity defined by the presence of usual interstitial pneumonia on high-resolution CT scan and/or open lung biopsy and the absence of an alternate diagnosis or exposure explaining these findings. There are currently no FDA-approved therapies available to treat this disease, and the 5-year mortality is ∼80%. The pyridone derivative pirfenidone has been studied extensively as a possible therapeutic agent for use in this deadly disease. This review will present the unique clinical features and management issues encountered by physicians caring for IPF patients, including the poor response to conventional therapy. The biochemistry and preclinical efficacy of pirfenidone will be discussed along with a comprehensive review of the clinical efficacy, safety, and side effects and patient-centered foci such as quality of life and tolerability. It is hoped that this information will lend insight into the complex issues surrounding the use of pirfenidone in IPF and lead to further investigation of this agent as a possible therapy in this devastating disease.

N-acetylcysteine attenuates dimethylnitrosamine induced oxidative stress in rats

Oxidative stress has been implicated in the pathogenesis and progression of various hepatic disorders and hence screening for a good hepatoprotective and antioxidant agent is the need of the hour. The present study was aimed to investigate the hepatoprotective and antioxidant property of N-acetylcysteine (NAC) against dimethylnitrosamine (DMN) induced oxidative stress and hepatocellular damage in male Wistar albino rats. Administration of single dose of DMN (5mg/kg b.w.; i.p.) resulted in significant elevation in the levels of serum aspartate transaminase and alanine transaminase, indicating hepatocellular damage. Oxidative stress induced by DMN treatment was confirmed by an elevation in the status of lipid peroxidation (LPO) and reduction in the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase and in the levels of non-enzymic antioxidants, reduced glutathione, vitamin-C and vitamin-E in the liver tissue. DMN induced oxidative stress and hepatocellular membrane instability was further substantiated by a decline in the status of the membrane bound ATPases in the liver tissue. Post-treatment with NAC (50mg/kg b.w.; p.o.) for 7days effectively protected against the DMN induced insult to liver by preventing the elevation in the status of the serum marker enzymes and LPO, and restoring the activities of both the enzymic and non-enzymic antioxidants and membrane bound ATPases towards normalcy. These results demonstrate that NAC acts as a good hepatoprotective and antioxidant agent in attenuating DMN induced oxidative stress and hepatocellular damage.

Pirfenidone: antifibrotic agent for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with rare incidence but high mortality, and the pathogenesis of which is still poorly understood. Available treatment options have been empirically applied but evidence-based benefits have not yet been confirmed. Pirfenidone is an antifibrotic agent that is potentially effective for IPF treatment. Preclinical studies have been reported using experimental animal models, which revealed inhibitory effects pn profibrotic and proinflammatory cytokines. Several clinical studies provided promising and reproducible effects for inhibition of IPF disease progression in different nations. The efficacy is demonstrated in patients with mild-to-moderate impairment of pulmonary functions, but not confirmed for patients with severe impairment. Major adverse events are photosensitivity and anorexia, but the treatment was generally safe and well tolerated. In this article, the usefulness and limitations of pirfenidone in IPF treatment are discussed to determine its potential for the management of IPF progression.

Investigational approaches to therapies for idiopathic pulmonary fibrosis

IMPORTANCE OF THE FIELD

In fibrosing diseases, scar tissue begins to replace normal tissue, causing tissue dysfunction. For instance, in lung fibrosis, foci of what resembles scar tissue form in the lungs, impeding the ability of patients to breathe. These conditions represent a significant source of morbidity and mortality. More than 150,000 people in the USA have some form of fibrotic lung disease, and the 5-year mortality rate for these diseases can be as high as 80%. Despite this large unmet medical need, there are no FDA-approved therapies. Although our understanding of the causes and the biology of fibrosing diseases remains relatively poor, we have made impressive advances in identifying the major cell populations and many biochemical mediators that can drive this process. As a result, novel therapeutics are being developed based upon these discoveries.

AREAS COVERED IN THIS REVIEW

This review examines the experimental therapies currently under investigation as of late 2009 for a major class of lung fibrosis called idiopathic pulmonary fibrosis (IPF).

WHAT THE READER WILL GAIN

The reader will gain an overview of current experimental therapies for IPF.

TAKE HOME MESSAGE

With the recent approval of Pirfenidone in Japan for use in IPF, and a rich pipeline of experimental therapies in various stages of clinical development, the future looks bright for new treatment options.

Pirfenidone: an anti-fibrotic therapy for progressive kidney disease

IMPORTANCE OF THE FIELD

Many chronic diseases of various etiologies lead to fibrosis and organ dysfunction. Despite many advances in medicine in recent years, options to slow the progression of fibrotic diseases have remained limited. The recent availability of pirfenidone, an antifibrotic and anti-inflammatory investigational agent, thus offers a new hope for treating progressive fibrotic diseases.

AREAS COVERED IN THIS REVIEW

This review provides concise review of the available data regarding the mechanism and pharmacokinetics of pirfenidone and preclinical and clinical data regarding efficacy and safety in fibrotic diseases of the kidney. It also reviews results of clinical trials involving pirfenidone in other fibrotic diseases.

WHAT THE READER WILL GAIN

The review will provide in-depth review of pirfenidone with a renal focus.

TAKE HOME MESSAGE

Because many of the available clinical trials have been small and/or uncontrolled, conclusive evidence regarding efficacy and safety of pirfenidone is lacking, particularly in patients with renal or hepatic dysfunction. Larger studies are needed to better understand long-term efficacy and safety of this medication in various patient populations.

Selective inhibition of activated stellate cells and protection from carbon tetrachloride-induced liver injury in rats by a new PPARgamma agonist KR62776

Activated hepatic stellate cells (HSC) are the primary source of extracellular matrix proteins found in liver fibrosis/cirrhosis patients. Therefore, the prevention of HSC activation is an important strategy for treating severe liver injury. This study examined the effects of KR62776, a new peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, on the rate of cell proliferation and expression of alpha-smooth muscle actin (alpha-SMA) in rat hepatic stellate HSC-T6 cells. In addition, its effects on the liver damage induced by carbon tetrachloride were investigated. KR62776 caused the apoptosis of activated HSC-T6 cells with the concomitant decrease in the alpha-smooth muscle actin levels in a time- and concentration-dependent manner. However, KR62776 did not cause the apoptosis of human HepG2 and rat McARH7777 hepatoma cells, suggesting that KR62776 has a specific effect on stellate cells. KR62776 increased the levels of Gadd45, p27, p21 and PPARgamma proteins but decreased the cell cyclerelated proteins, such as cdk2, cyclin B and cyclin D1. These changes were reversed by BADGE, a specific PPARgamma antagonist, indicating that the effects of KR62776 are, at least in part, PPARgamma-dependent. In addition, KR62776 administration showed some protection against carbon tetrachloride-induced hepatocellular damage in rats. Overall, these results suggest that KR62776 may have potential in the chemoprevention of liver fibrosis/cirrhosis.

Pirfenidone inhibits carbon tetrachloride- and albumin complex-induced liver fibrosis in rodents by preventing activation of hepatic stellate cells

1. Pirfenidone (PFD; 5-methyl-1-phenyl-2(1H)-pyridone) is an effective and novel agent with antifibrotic and anti-inflammatory properties. In the present study, we investigated the antifibrotic effects of PFD on experimental liver fibrosis models in rodents and the possible underlying molecular mechanisms. 2. Liver fibrosis was induced by carbon tetrachloride (CCl(4)) in BALB/c mice. Pirfenidone (250 mg/kg) and silymarin (50 mg/kg) were given to different groups of rats by gastric gavage for 4 weeks. Pirfenidone significantly attenuated fibrosis severity, as determined by histopathological scores and hydroxyproline levels in liver tissue, by 49.8 and 44.9%, respectively, compared with the CCl(4)-treated group. The antifibrotic effects of PFD were significantly greater than those of silymarin, as indicated by a decrease of 23.5 and 24.8% in histopathological scores and hydroxyproline levels, respectively. 3. Liver fibrosis was also induced by albumin antigen-antibody complex in Wistar rats, which were then treated with the same doses of PFD and silymarin for 8 weeks. Pirfenidone significantly reduced the degree of fibrosis compared with CCl(4)-treated rats (by 45.0 and 51.0% as determined by histopathological scores and hydroxyproline levels in liver tissue, respectively). The antifibrotic effects of PFD were comparable to those of silymarin. 4. The effects of PFD on the expression of extracellular matrix-associated genes in human hepatic stellate cells (the LX-2 cell line) were measured by real-time quantitative polymerase chain reaction. LX-2 cells were treated with or without 100 micromol/L or 1 mmol/L PFD for 24 h. Pirfenidone significantly inhibited the expression of a-smooth muscle actin and Type I collagen in 8 ng/mL transforming growth factor-beta1- or 5% fetal bovine serum-activated LX-2 cells in a dose-dependent manner. 5. In conclusion, the results of the present study demonstrate that PFD is effective in ameliorating fibrogenesis induced by CCl(4) in mice and by the albumin complex in rats. These effects were mediated mainly via inhibition of the activation of hepatic stellate cells, as well as antifibrotic actions (i.e. inhibition of collagen synthesis) of PFD.

Current and future anti-fibrotic therapies for chronic liver disease

Chronic injury results in a wound healing response that eventually leads to fibrosis. The response is generalized, with features common among multiple organ systems. In the liver, various different types of injury lead to fibrogenesis, implying a common pathogenesis. Although several specific therapies for patients who have different liver diseases have been successfully developed, including antiviral therapies for those who have hepatitis B and hepatitis C virus infection, specific and effective antifibrotic therapy remains elusive. Over the past 2 decades, great advances in the understanding of fibrosis have been made and multiple mechanisms underlying hepatic fibrogenesis uncovered. Elucidation of these mechanisms has been of fundamental importance in highlighting novel potential therapies. Preclinical studies have indicated several putative therapies that might abrogate fibrogenesis. This article emphasizes mechanisms underlying fibrogenesis and reviews available and future therapeutics.

Potent antioxidant role of pirfenidone in experimental cirrhosis

Three important features must be considered when proposing therapeutic strategies in liver cirrhosis: inflammation, oxidative stress and fibrogenesis. Pirfenidone is a synthetic molecule which oxidative action has not been tested in cirrhosis. Cirrhosis was induced in rats by ligation of the common bile duct or carbon tetrachloride (CCl(4)) chronic intoxication and treated with pirfenidone or diphenyleneiodonium (a potent known antioxidant) for the last two weeks for bile duct ligation model or for the last three weeks for CCl(4) chronic intoxication. A 60% reduction in fibrosis index for bile duct ligation model and 42% for CCl(4) along with reduced inflammation was observed. Considerable reduction on hepatic enzymes and total and direct bilirubins were detected with pirfenidone in both models. Pirfenidone antioxidant capacity rendered a 28% and 30% reduction in nitrites and malonyldealdehide concentration in bile duct ligation and 52% and 38% in CCl(4). With respect to gene expression, fibrotic genes like transforming growth factor-beta (TGF-beta) and collagen Ialpha (Col-1alpha) were down-regulated by pirfenidone and increased expression of regenerative genes like hepatocyte growth factor (HGF) and c-met . Superoxide dismutase (SOD), catalase (CAT) and inducible nitric oxide synthase (iNOS) gene expression were importantly down-regulated where nuclear factor kappa B (NF-kappaB) binding activity also decreased with pirfenidone treatment. Also, SOD and CAT functional activity decreased after pirfenidone action. On the other hand, diphenyleneiodonium induced a drop in oxidative stress similar in extent to pirfenidone, but it was not as effective as pirfenidone in reducing fibrosis. In this work, we showed antioxidant properties of pirfenidone beyond its well-known antifibrotic effect. These features make pirfenidone an attractive drug for trying fibrotic diseases accompanied by oxidative stress processes.

Pharmacokinetics and metabolism of intravenous pirfenidone in sheep

Pirfenidone, a promising antifibrotic agent, was administered intravenously to six female sheep at 30 mg/kg. Four sheep received 14C-pirfenidone simultaneously. Plasma and urine were obtained for assay of pirfenidone and its metabolites over two days, and tissues were obtained via necropsy. Samples were analysed for pirfenidone and metabolites using HPLC-MS and flow scintillation spectrometry. Plasma pirfenidone disappeared with first order kinetics with a clearance of 1.2 l/kg/h, half-life of 24 min, and distribution volume of 0.71 l/kg. After 48 h, the organs containing the largest quantity of 14C were lungs, liver and intestinal wall. Tissues with the highest concentration of 14C were lung, kidney, brain, liver, lymph node and adipose. Metabolites found in plasma and urine were hydroxypirfenidone (half-life of 44 min) and carboxypirfenidone. Additional metabolites found in urine were hydroxypirfenidone glucuronide and acetoxypirfenidone. Approximately, 80% of the tracer eventually appeared in the urine, and approximately 50% of it was in the form of identifiable metabolites. Less than 1% of the dose appeared in the urine in the form of the parent drug. Quantitatively, most of the metabolites appeared in the urine within 2 h. Thus, the drug is rapidly and completely metabolized.

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.

Simple determination of pirfenidone in rat plasma via high-performance liquid chromatography

A simple, rapid and reliable high-performance liquid chromatographic method was developed and validated for the determination of pirfenidone and its major metabolites in rat plasma. Plasma proteins were precipitated with perchloric acid (10%, v/v) and the supernatant after centrifugation was determined using high-performance liquid chromatography. The analysis was carried out on a Lichrospher C(18) column (250 x 4.6 mm i.d., 5 microm). The mobile phase consisted of acetonitrile-water containing 0.2% acetic acid (23:77, v/v) at a flow-rate of 1 mL/min. The eluant was detected at 310 nm. The calibration curves were linear over a concentration range from 0.15 to 76.67 microg/mL. The accuracy (relative error) of the assay ranged from -2.6 to 7.9% and the precision (coefficient of variation) was less than 4.5%. The established method has been successfully applied to a pharmacokinetic study of pirfenidone following a single oral dose to rats.

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 modulates airway responsiveness, inflammation, and remodeling after repeated challenge

We investigated the therapeutic potential of a newly developed antifibrotic agent, pirfenidone, to regulate airway remodeling and the development of allergic airway inflammation and airway hyperresponsiveness after chronic allergen challenge. Administration of pirfenidone after sensitization but during the period of ovalbumin challenge significantly prevented the development of airway hyperresponsiveness and prevented eosinophil and lymphocyte accumulation in the airways. IL-4, IL-5, and IL-13 levels in bronchoalveolar lavage fluid and ovalbumin-specific serum IgE antibody levels were also significantly reduced. Treatment with pirfenidone significantly reduced transforming growth factor-beta1 and platelet-derived growth factor levels in bronchoalveolar lavage fluid. Pirfenidone reduced the expression of transforming growth factor-beta1, the development of goblet cell hyperplasia and subepithelial collagenization, and the increases in contractile elements in the lung. These data indicate that pirfenidone may play an important role in the treatment of asthma and has the potential reduce or prevent airway remodeling.

Long-term administration of pirfenidone improves cardiac function inmdx mice

Duchenne muscular dystrophy, an X-linked recessive neuromuscular disorder due to lack of the protein dystrophin, manifests as progressive muscle degeneration and cardiomyopathy with increased fibrosis. The exact mechanisms involved in fibrosis are unknown, but a cytokine, transforming growth factor-beta (TGF-beta), is a likely mediator. This study tested whether the TGF-beta antagonist, pirfenidone, could reduce cardiac fibrosis. Eight-month-old mdx mice were treated for 7 months with 0.4%, 0.8%, and 1.2% pirfenidone in drinking water; untreated water was given to control mdx and C57 mice. Mice treated with 0.8% and 1.2% pirfendone had lowered cardiac TGF-beta mRNA and improved in vitro cardiac contractility (P < 0.05) to levels consistent with C57 mice, yet without a change in cardiac stiffness or fibrosis. These results show that the TGF-beta antagonist, pirfenidone, can improve cardiac function in mdx mice, potentially providing a new avenue for developing cardiac therapies for patients with Duchenne muscular dystrophy.

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.

Pirfenidone inhibits lung allograft fibrosis through L-arginine-arginase pathway

Transplant-related lung fibrosis is characterized by excessive fibro-collagenous deposition. Induction of arginase, an enzyme that metabolizes L-arginine to urea and L-ornithine, is vital for collagen synthesis. Pirfenidone is an investigational anti-fibrotic agent shown to be effective in blocking pulmonary fibrosis. The purpose of this study was to determine if pirfenidone was protective against the development of fibro-collagenous injury in rat lung orthotopic transplants through altering L-arginine-arginase metabolic pathways. Lung transplants were performed using Lewis donors and Sprague-Dawley recipients (allografts) or the same strain (isografts). Recipients were given pirfenidone (0.5% chow) 1-21-day post-transplantation. A significantly increased peak airway pressure (PawP) with excessive collagen deposition was found in untreated lung allografts. Pirfenidone treatment decreased PawP and collagen content in lung allografts. The beneficial effects were associated with downregulation of arginase protein expression and activity. In addition, pirfenidone decreased endogenous transforming growth factor (TGF)-beta level in lung allografts, and TGF-beta stimulated arginase activity in a dose-dependent manner in both lung tissue and fibroblasts. These results suggest that pirfenidone inhibits local arginase activity possibly through suppression of endogenous TGF-beta, hence, limiting the development of fibrosis in lung allografts.

Pharmacokinetics of orally administered pirfenidone in male and female beagles

Pirfenidone, a promising antifibrotic agent, was administered orally to dogs at 0, 40, 140, and 400 mg/kg/day. Serum was collected for pirfenidone assay at 0, 26 and 39 weeks of treatment. From the pirfenidone concentrations, pharmacokinetic parameters were determined for each dog at each treatment interval. The only significant differences because of gender were for concentration maxima. Unsurprisingly, there were many significant differences because of dose in concentration maximum and area under curve (AUC), and significant, positive linear correlations of both parameters with dose. There were few significant differences in time of maximal concentration and no correlation with dose. The mean +/- SE clearances were 1.99 +/- 0.13, 1.64 +/- 0.13 and 1.78 +/- 0.14 L/h/kg for doses of 40, 140, and 400 mg/kg, respectively, with no significant differences attributable to dose. There was an unexplained pattern in maximal concentration and AUC with regard to duration of treatment, with the parameters being highest at week 0, lowest at week 26, and intermediate at week 39. Clearance had the reverse pattern; time of maximal concentration had no pattern.

The anti-fibrotic effect of pirfenidone in rat liver fibrosis is mediated by downregulation of procollagen alpha1(I), TIMP-1 and MMP-2

BACKGROUND

Pirfenidone (5 methyl-1-phenyl-2(1H)-pyridone) is a novel anti-fibrotic agent, which has been shown to decrease collagen deposition in a variety of animal models in vivo, and recently in hepatic fibrosis also. At cellular level, we have recently demonstrated that pirfenidone is able to inhibit proliferation of hepatic stellate cells induced by platelet-derived growth factor, as well as collagen type I accumulation and alpha1(I) procollagen mRNA expression.

AIMS

To evaluate if pirfenidone maintains its anti-fibrotic properties also when administered after the induction of hepatic damage and to further investigate the molecular mechanisms leading to the anti-fibrotic effect of pirfenidone.

METHODS AND RESULTS

Rats treated with dimethylnitrosamine (10 mg/kg) for 5 weeks received a liquid diet containing 0.5% pirfenidone starting from the third week. Pirfenidone treatment reduced the degree of liver injury, as determined by alanine aminotransferase values and necro-inflammatory score, which was associated with reduced hepatic stellate cells proliferation and collagen deposition. Treatment with dimethylnitrosamine increased transcripts levels for transforming growth factorbeta1, procollagen alpha1(I), tissue inhibitors of metalloproteinase-1 and matrix metalloproteinase-2 by 7-, 7-, 4- and 15-fold, respectively. Pirfenidone administration downregulated elevated levels of those transcripts by 50-60%, and this was associated with a 70% reduction in collagen deposition.

CONCLUSIONS

(1) Pirfenidone is effective also if administered after the induction of the hepatic damage; (2) the anti-fibrotic effect of pirfenidone is mainly due to the reduced expression of profibrogenic procollagen alpha1(I) and TIMP-1, most likely through the downregulation of transforming growth factorbeta1 mRNA, and of matrix metalloproteinase-2, which is mainly implicated in the degradation of the normal extracellular matrix.

Pirfenidone inhibits the induction of iNOS stimulated by interleukin-1beta at a step of NF-kappaB DNA binding in hepatocytes

BACKGROUND/AIMS

Pirfenidone has antiinflammatory effects in animals with endotoxemia. We reported that pirfenidone inhibits the enhancement of inflammatory cytokines and inducible nitric oxide synthase (iNOS) in liver of endotoxin-treated rats, leading to the prevention of hepatic injury. However, the mechanisms involved in suppression of these gene inductions are obscure. Studies were performed to investigate whether pirfenidone directly influences iNOS induction in hepatocytes.

METHODS

Cultured hepatocytes were treated with interleukin-1beta (IL-1beta) in the presence and absence of pirfenidone, and iNOS induction and its signal including NF-kappaB were analyzed.

RESULTS

Pirfenidone inhibited the induction of iNOS mRNA and protein, resulting in the decrease of nitric oxide production. Gel shift assay demonstrated that pirfenidone inhibited the activation of NF-kappaB. Consistent with this observation, transfection experiments revealed that pirfenidone decreased transcriptional activation of iNOS gene promoter. In contrast, pirfenidone had no effect on the degradation of IkappaB, and could not prevent nuclear translocation of p50/p65. Finally, pirfenidone inhibited the activation of Akt and up-regulation of IL-1 receptor stimulated by IL-1beta.

CONCLUSIONS

Results indicate that pirfenidone inhibits the induction of iNOS gene expression at a step of NF-kappaB DNA binding, but not its nuclear translocation, partly through the inhibition of IL-1 receptor induction in hepatocytes.