Pirfenidone inhibits inflammatory responses and ameliorates allograft injury in a rat lung transplant model

Ferroptosis-A New Dawn in the Treatment of Organ Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) is a common pathological phenomenon that occurs in numerous organs and diseases. It generally results from secondary damage caused by the recovery of blood flow and reoxygenation, followed by ischemia of organ tissues, which is often accompanied by severe cellular damage and death. Currently, effective treatments for I/R injury (IRI) are limited. Ferroptosis, a new type of regulated cell death (RCD), is characterized by iron overload and iron-dependent lipid peroxidation. Mounting evidence has indicated a close relationship between ferroptosis and IRI. Ferroptosis plays a significantly detrimental role in the progression of IRI, and targeting ferroptosis may be a promising approach for treatment of IRI. Considering the substantial progress made in the study of ferroptosis in IRI, in this review, we summarize the pathological mechanisms and therapeutic targets of ferroptosis in IRI.

Multifaceted Roles of Ferroptosis in Lung Diseases

Ferroptosis is a distinct type of programmed cell death (PCD) that depends on iron and is characterized by the accumulation of intracellular iron, exhaustion of glutathione, deactivation of glutathione peroxidase, and promotion of lipid peroxidation. Recently, accumulated investigations have demonstrated that ferroptosis is strongly correlated with the initiation and development of many lung diseases. In this review, we summarized the contribution of ferroptosis to the pathologic process of lung diseases, namely, obstructive lung diseases (chronic obstructive pulmonary disease, asthma, and cystic fibrosis), interstitial lung diseases (pulmonary fibrosis of different causes), pulmonary diseases of vascular origin (ischemia-reperfusion injury and pulmonary hypertension), pulmonary infections (bacteria, viruses, and fungi), acute lung injury, acute respiratory distress syndrome, obstructive sleep apnea, pulmonary alveolar proteinosis, and lung cancer. We also discussed the therapeutic potential of targeting ferroptosis for these lung diseases.

Antifibrotic drugs in lung transplantation and chronic lung allograft dysfunction: a review

This review aims to provide an overview of pre-transplant antifibrotic therapy on peri-transplant outcomes and to address the possible role of antifibrotics in lung transplant recipients with chronic lung allograft dysfunction.Lung transplantation is an established treatment modality for patients with various end-stage lung diseases, of which idiopathic pulmonary fibrosis and other progressive fibrosing interstitial lung diseases are growing indications. Theoretically, widespread use of antifibrotics prior to lung transplantation may increase the risk of bronchial anastomotic complications and impaired wound healing.Long-term graft and patient survival are still hampered by development of chronic lung allograft dysfunction, on which antifibrotics may have a beneficial impact.Antifibrotics until the moment of lung transplantation proved to be safe, without increasing peri-transplant complications. Currently, best practice is to continue antifibrotics until time of transplantation. In a large multicentre randomised trial, pirfenidone did not appear to have a beneficial effect on lung function decline in established bronchiolitis obliterans syndrome. The results of antifibrotic therapy in restrictive allograft syndrome are eagerly awaited, but nonrandomised data from small case reports/series are promising.

Antifibrotic drugs in connective tissue disease-related interstitial lung disease (CTD-ILD): from mechanistic insights to therapeutic applications

Fibrosing interstitial lung disease (ILD) is one of the most important causes of morbidity and mortality in patients with connective tissue diseases (CTDs), which include systemic sclerosis, rheumatoid arthritis, Sjögren's syndrome, idiopathic inflammatory myositis and systemic lupus erythematosus. The treatment of CTD-ILDs is challenging due to the paucity of proven effective treatments. Recently, two antifibrotic drugs conditionally approved for use in patients with idiopathic pulmonary fibrosis, nintedanib and pirfenidone, have been trialled in CTD-ILDs based on overlapping pathological and clinical features between the two diseases. In this narrative review, we discuss the experimental evidence and clinical trials investigating the efficacy and safety of antifibrotic drugs in patients with CTD-ILDs and the potential mechanisms of action involved. Results from clinical trials suggest that nintedanib use retards lung function decline in progressive fibrotic CTD-ILDs. By contrast, the evidence for the efficacy of pirfenidone in these groups is not equally compelling. Further, well-designed randomized clinical trials are needed to evaluate the efficacy and safety of individual antifibrotic drugs in specific CTD-ILD subgroups.

Pirfenidone: Molecular Mechanisms and Potential Clinical Applications in Lung Disease

Pirfenidone (PFD) is a pharmacological compound with therapeutic efficacy in idiopathic pulmonary fibrosis. It has been chiefly characterized as an antifibrotic agent, although it was initially developed as an antiinflammatory compound because of its ability to diminish the accumulation of inflammatory cells and cytokines. Despite recent studies that have elucidated key mechanisms, the precise molecular activities of PFD remain incompletely understood. PFD modulates fibrogenic growth factors, thereby attenuating fibroblast proliferation, myofibroblast differentiation, collagen and fibronectin synthesis, and deposition of extracellular matrix. This effect is mediated by suppression of TGF-β1 (transforming growth factor-β1) and other growth factors. Here, we appraise the impact of PFD on TGF-β1 production and its downstream pathways. Accumulating evidence indicates that PFD also downregulates inflammatory pathways and therefore has considerable potential as a viable and innovative antiinflammatory compound. We examine the effects of PFD on inflammatory cells and the production of pro- and antiinflammatory cytokines in the lung. In this context, recent evidence that PFD can target inflammasome pathways and ensuing lung inflammation is highlighted. Finally, the antioxidant properties of PFD, such as its ability to inhibit redox reactions and regulate oxidative stress-related genes and enzymes, are detailed. In summary, this narrative review examines molecular mechanisms underpinning PFD and its recognized benefits in lung fibrosis. We highlight preclinical data that demonstrate the potential of PFD as a nonsteroidal antiinflammatory agent and outline areas for future research.

Pirfenidone exerts beneficial effects in patients with IPF undergoing single lung transplantation

Pirfenidone demonstrated pleiotropic antiinflammatory effects in various experimental and clinical settings. The aim of this study was to assess the impact of previous treatment with pirfenidone on short-term outcomes after single lung transplantation (SLTx). Therefore, patients with idiopathic pulmonary fibrosis (IPF) who were undergoing SLTx were screened retrospectively for previous use of pirfenidone and compared to respective controls. Baseline parameters and short-term outcomes were recorded and analyzed. In total, 17 patients with pirfenidone were compared with 26 patients without antifibrotic treatment. Baseline characteristics and severity of disease did not differ between groups. Use of pirfenidone did not increase blood loss, wound-healing, or anastomotic complications. Severity of primary graft dysfunction at 72 hours was less (0.3 ± 0.6 vs 1.4 ± 1.3, P = .002), and length of mechanical ventilation (37.5 ± 34.8 vs 118.5 ± 151.0 hours, P = .016) and intensive care unit (ICU) stay (6.6 ± 7.1 vs 15.6 ± 20.3, P = .089) were shorter in patients with pirfenidone treatment. An independent beneficial effect of pirfenidone was confirmed by regression analysis while controlling for confounding variables (P = .016). Finally, incidence of acute cellular rejections within the first 30 days after SLTx was lower in patients with previous pirfenidone treatment (0.0% vs 19.2%; P = .040). Our data suggest a beneficial role of previous use of pirfenidone in patients with IPF who were undergoing SLTx.

Pirfenidone in restrictive allograft syndrome after lung transplantation: A case series

Pirfenidone may attenuate the decline of pulmonary function in restrictive allograft syndrome (RAS) after lung transplantation. We retrospectively assessed all lung transplant recipients with RAS who were treated with pirfenidone for at least 3 months (n = 11) in our lung transplant center and report on their long-term outcomes following initiation of pirfenidone. Main outcome parameters included evolution of pulmonary function and overall survival. Pirfenidone appears to attenuate the decline in forced vital capacity and forced expiratory volume in 1 second. Notably, 3 patients were bridged to redo-transplantation with pirfenidone for 11 (5-12) months and are currently alive, while 3 other patients demonstrate long-term stabilization of pulmonary function after 26.6 (range 18.4-46.6) months of treatment. Median overall 3-year survival after RAS diagnosis was 54.5%. Subjective intolerance, mainly anorexia and nausea, necessitating pirfenidone dose de-escalation in 55% of patients, as well as calcineurin dose increase requirements with about 20% are important complications during pirfenidone treatment after lung transplantation. Our findings provide further evidence that pirfenidone appears to be safe and may attenuate the rate of decline in lung function in patients with RAS, but the actual clinical benefit cannot be assessed in the context of this study design and requires further investigation in a larger randomized trial.

Histopathological and molecular analysis of idiopathic pulmonary fibrosis lungs from patients treated with pirfenidone or nintedanib

AIMS

The objective of this study was to quantify the impact of pirfenidone or nintedanib treatment on lung histopathology and molecular mediators of fibrosis in patients with idiopathic pulmonary fibrosis (IPF).

METHODS AND RESULTS

We collected lung tissue from IPF patients at the time of lung transplantation. Histopathological changes were quantified using a blinded scoring method. Proteins associated with senescence or active TGF-β were quantified in lung tissues by immunoblot and immunostaining. Histopathological quantification showed similar amounts of dense collagen fibrosis, fibroblast foci and alveolar macrophages in untreated or pirfenidone- or nintedanib-treated IPF patients. There was less diffuse alveolar damage and organising pneumonia in pirfenidone-treated IPF patients. Lungs of nintedanib-treated patients had a trend towards less lymphocytic interstitial infiltration. There was no difference in expression of p-SMAD3, p21 or p16 in the lungs of untreated, pirfenidone- or nintedanib-treated IPF patients. Alveolar epithelial cells, but not fibroblast foci, were immunoreactive to p16. Pirfenidone or nintedanib treatment did not inhibit activation of senescence programming in cultured lung epithelial cells mediated by hydrogen peroxide.

CONCLUSION

Pirfenidone and nintedanib do not modulate expression of senescence markers, levels of p-SMAD3 or the amount of fibrosis in IPF lungs. Treated patients have less histopathological evidence of acute lung injury at the time of lung transplantation.

Pirfenidone alleviates lung ischemia-reperfusion injury in a rat model

OBJECTIVE

Lung ischemia-reperfusion injury is among the complications seen after lung transplantation, resulting in morbidity and mortality. Pirfenidone, an antifibrotic agent for the treatment of idiopathic pulmonary fibrosis, is reported to have cytoprotective properties in various disease models. The purpose of this study was to investigate the effect of pirfenidone on lung ischemia-reperfusion injury.

METHODS

Male Lewis rats (260-290 g) were divided into 3 groups: sham group (n = 5), warm ischemia (WI) group (n = 10), and WI plus pirfenidone (WI+PFD) group (n = 10). The sham group underwent 210 minutes of perfusion without ischemia. The WI and WI+PFD groups underwent 90 minutes of warm ischemia and 120 minutes of reperfusion. In the WI+PFD group, pirfenidone (300 mg/kg) was administered orally by gavage 30 minutes before ischemia. After reperfusion, arterial blood gas analysis, lung mechanics, lung wet-to-dry weight ratio, and histologic findings were obtained. The gene expressions of proinflammatory cytokines in lung tissue were measured by quantitative reverse transcription polymerase chain reaction.

RESULTS

Compared with the WI group, the WI+PFD group had significantly better dynamic pulmonary compliance (P < .01) and oxygenation levels (P < .05). The wet-to-dry ratio was lower in the WI+PFD group (P < .05). Histologic analysis showed that the WI+PFD group had reduced perivascular edema and neutrophil infiltration. The expression of tumor necrosis factor-α messenger RNA was decreased in the WI+PFD group (P < .05).

CONCLUSIONS

Our results revealed that in a rat hilar clamp model, pirfenidone alleviated lung ischemia-reperfusion through anti-inflammatory effects.

Pirfenidone protects against paraquat-induced lung injury and fibrosis in mice by modulation of inflammation, oxidative stress, and gene expression

In this study we investigated the protective effects and possible mechanisms of pirfenidone (PF) in paraquat (PQ)-induced lung injury and fibrosis in mice. Lung injury was induced by injection of PQ (20 mg/kg). Thereafter, mice orally received water and PF (100 and 200 mg/kg) for four weeks. After 28 days, the inflammation and fibrosis were determined in the lungs by analysis of histopathology, bronchoalveolar lavage fluid (BALF) cell count, lung wet/dry weight ratio, hydroxyproline content, and oxidative stress biomarkers. Expression of several genes involved in fibrogenesis and modulation of reactive oxygen species (ROS) production, such as TGF-β1, α-SMA, collagen Iα and IV, NOX1, NOX4, iNOS, and GPX1 were determined using RT-qPCR. PF significantly decreased the lung fibrosis and edema, inflammatory cells infiltration, TGF-β1 concentration, and amount of hydroxyproline in the lung tissue. PF dose-dependently improved the expression level of the studied genes to the near normal. Decreasing of lung lipid peroxidation and catalase activity, and increasing of SOD activity in the treated mice were significant compared to the control group. Pirfenidone ameliorate paraquat induced lung injury and fibrosis partly through inhibition of inflammation and oxidative stress, and downregulation of genes encoding for profibrotic cytokines and enzymatic systems for ROS production.

Pirfenidone for primary Sjögren's syndrome-related fibrotic interstitial pneumonia

Primary Sjögren's syndrome-related interstitial pneumonia (pSS-IP) is occasionally progressive even with immunosuppressive therapy and new treatment options are warranted. A 42-year-old woman was diagnosed with pSS-IP with pathological usual interstitial pneumonia pattern. Although her forced vital capacity (FVC) had temporarily improved after prednisolone therapy, it deteriorated during the prednisolone tapering off period. Therefore, pirfenidone was added in conjunction with prednisolone. During the 12-month treatment period, her FVC was almost stable. A 62-year-old man, a current heavy smoker, was diagnosed with pSS-IP. Chest computed tomography showed bilateral honeycombing with ground-glass attenuation on a background of emphysema. He gradually developed dyspnea on exertion and his FVC deteriorated. Hence, pirfenidone was administered as a monotherapy. Six months later, his FVC and exercise tolerance had significantly improved. Pirfenidone might have a role for the treatment of pSS-IP. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 91-96).

Interleukin-1α induced release of interleukin-8 by human bronchial epithelial cells in vitro: assessing mechanisms and possible treatment options

Survival after lung transplantation is hampered by chronic lung allograft dysfunction (CLAD). Persistently elevated BAL-neutrophilia is observed in some patients despite treatment with azithromycin, which may be induced by IL-1α. Our aim is to establish an in vitro model, assess mechanistic pathways and test different therapeutic strategies of IL-1α-induced release of IL-8 by human bronchial epithelial cells. Bronchial epithelial cells (16HBE) were stimulated with IL-1α with or without azithromycin or dexamethasone. IL-8 protein was analyzed in cell supernatant. Different MAP kinases (p38, JNK, ERK^1/2 , Iκβ) and targets known to be involved in tumor formation (PI3K, Akt) were investigated. Finally, different treatment options were tested for their potential inhibitory effect. IL-1α induced IL-8 in bronchial epithelial cells, which was dose-dependently inhibited by dexamethasone but not by azithromycin. IL-1α induced p38 and Akt phosphorylation, but activation of these MAPK was not inhibited by dexamethasone. JNK, ERK^1/2 , Iκβ and PI3K were not activated. None of the tested drugs reduced the IL-1α induced IL-8 production. We established an in vitro model wherein steroids inhibit the IL-1α-induced IL-8 production, while azithromycin was ineffective. Despite using this simple in vitro model, we could not identify a new treatment option for azithromycin-resistant airway neutrophilia.

Oxidative Modifications of Protein Tyrosyl Residues Are Increased in Plasma of Human Subjects with Interstitial Lung Disease

RATIONALE

Interstitial lung diseases (ILDs) are associated with oxidative stress. Plasma biomarkers that are directly linked to oxidative stress responses in this disease have not been identified. Stable oxidation products of tyrosine residues in proteins may reflect the oxidative microenvironment in the lung or a systemic inflammatory state.

OBJECTIVES

To determine if levels of protein tyrosine oxidation are elevated in plasma of patients with ILD compared with an age- and sex-matched healthy control cohort.

METHODS

Three tyrosine oxidation products (3-chlorotyrosine, 3-nitrotyrosine, and o,o'-dityrosine) were quantified by tandem mass spectrometry in cellular models, a mouse model of injury-induced fibrosis, and in plasma of healthy control subjects and patients with ILD (n = 42 in each group).

MEASUREMENTS AND MAIN RESULTS

Plasma levels of 3-chlorotyrosine, 3-nitrotyrosine, and o,o'-dityrosine were markedly elevated in patients with ILD compared with control subjects with receiver operating characteristic curves separating these groups of 0.872, 0.893, and 0.997, respectively. In a murine model of lung fibrosis, levels of all three oxidative tyrosine modifications were increased in plasma and lung tissue. Cellular models support a critical role for a heme peroxidase and enzymatic sources of reactive oxygen species in the generation of these oxidized products.

CONCLUSIONS

We demonstrate an increase in oxidized tyrosine moieties within proteins in the circulating plasma of patients with ILD. These data support the potential for development of oxidative stress-related biomarkers in early diagnosis, prognostication, and/or in evaluating responsiveness to emerging therapies for ILD.

Pharmacological treatment of idiopathic pulmonary fibrosis - preclinical and clinical studies of pirfenidone, nintedanib, and N-acetylcysteine

Three recent clinical trials on the pharmacologic treatment of idiopathic pulmonary fibrosis (IPF) mark a new chapter in the management of patients suffering from this very severe fibrotic lung disease. This review article summarizes the published investigations on the preclinical studies of three novel IPF drugs, namely pirfenidone, nintedanib, and N-acetylcysteine (NAC). In addition, the study protocols, differences, and the main findings in the recent clinical trials of these pharmacological treatments are reviewed. The strategy for drug development and the timeline from the discovery to the clinical use have been very different in these regimens. Pirfenidone was discovered in 1976 but only recently received approval in most countries, and even now its exact mechanism of action is unknown. On the contrary, nintedanib (BIBF1120) was identified in large drug screening tests as a very specific inhibitor of certain tyrosine kinases, but no published data on preclinical tests existed until 2014. NAC, a mucolytic drug with an antioxidant mechanism of action was claimed to possess distinct antifibrotic properties in several experimental models but proved to be ineffective in a recent randomized placebo-controlled trial. At present, no curative treatment is available for IPF. A better understanding of the molecular mechanisms of IPF as well as relevant preclinical tests including animal models and in vitro experiments on human lung cells are needed to promote the development of therapeutic drugs.

Functional and structural impact of pirfenidone on the alterations of cardiac disease and diabetes mellitus

A synthetic compound, termed pirfenidone (PFD), is considered promising for the treatment of cardiac disease. It leads to beneficial effects in animal models of diabetes mellitus (DM); as well as in heart attack, atrial fibrillation, muscular dystrophy, and diabetic cardiomyopathy (DC). The latter is a result of alterations linked to metabolic syndrome as they promote cardiac hypertrophy, fibrosis and contractile dysfunction. Although reduced level of fibrosis and stiffness represent an essential step in the mechanism of PFD action, a wide range of functional effects might also contribute to the therapeutic benefits. For example, PFD stimulates L-type voltage-gated Ca(2+) channels (LTCCs), which are pivotal for a process known as excitation-contraction coupling (ECC). Recent evidence suggests that these two types of actions - namely structural and functional - aid in treating both cardiac disease and DM. This view is supported by the fact that in DC, for example, systolic dysfunction arises from both cardiac stiffness linked to fibrosis and down-regulation of ECC. Thus, not surprisingly, clinical trials have been conducted with PFD in the settings of DM, for treating not only cardiac but also renal disease. This review presents all these concepts, along with the possible mechanisms and pathophysiological consequences.

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.

Pirfenidone inhibits macrophage infiltration in 5/6 nephrectomized rats

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

Pirfenidone: significant treatment effects in idiopathic pulmonary fibrosis

Pirfenidone has been shown in three recently published trials to slow down the progression of the devastating interstitial lung disease, idiopathic pulmonary fibrosis (IPF). The precise mechanisms that initiate and perpetuate the histopathological process leading to lung fibrosis in IPF are still uncertain, but increased concentrations of reactive oxidative species and fibrogenetic factors have been observed in the pulmonary tissue of patients. Although the exact mechanisms of its action are unknown, pirfenidone is a small molecule with antifibrotic and some hydroxyl scavenger properties that has recently been approved in Europe and elsewhere for the treatment of IPF. Along with the new ATS/ERS/JRS/ALAT 2011 statement for 'Evidence Based Guidelines for Diagnosis and Management', there is now a more profound basis for offering IPF patients an evidence-based evaluation and treatment. This review summarizes the background to the recommended use of pirfenidone for the treatment of IPF.

Inhibitory effects of pirfenidone on dendritic cells and lung allograft rejection

BACKGROUND

Pirfenidone (PFD) is an antifibrotic agent with beneficial effects on proinflammatory disorders. In this study, we further investigated PFD and long-acting form, "deuterated PFD," immune-modulating properties by evaluating their effects on mouse dendritic cells (DCs).

METHODS

The effects of PFD on DCs were examined in vivo using an orthotopic mouse lung transplant model and in vitro using isolated bone marrow-derived DCs in response to lipopolysaccharide and allogeneic stimulation.

RESULTS

In mouse lung transplants, PFD and deuterated PFD treatment improved allograft lung function based on peak airway pressure, less infiltrates/consolidation on micro-computed tomography scan imaging, and reduced lung rejection/injury. DC activation from lung allografts was suppressed with PFD, and there seemed to be a greater effect of PFD on CD11c(+)CD11b(-)CD103(+) lung DCs. In addition, PFD reduced the expression of several proinflammatory cytokines/chemokines from lung allografts. In vitro, DCs treated with PFD showed decreased expression of major histocompatibility complex class II and costimulatory molecules and the capacity of these DCs to stimulate T-cell activation was impaired, although antigen uptake was preserved. PFD directly inhibited the release of inflammatory cytokines from isolated DCs, was associated with a reduction of stress protein kinases, and attenuated lipopolysaccharide-dependent mitogen-activated protein kinase p38 phosphorylation.

CONCLUSIONS

PFD has lung allograft protective properties, and in addition to its known effects on T-cell biology, PFD immune-modulating activities encompass inhibitory effects on DC activation and function.

Split-liver procedure and inflammatory response: improvement by pharmacological preconditioning

BACKGROUND

Final outcome of split-liver (SL) transplantation is impaired due to an increased rate of vascular complications and primary non-function. Herein, we hypothesized that an in situ split-liver procedure induces an inflammatory response and a deterioration of graft quality. We further studied whether graft quality can be improved by pharmacologic preconditioning.

MATERIAL AND METHODS

SL-procedure was performed in rats. One group (SL-HPP; n = 8) was pretreated according to a defined protocol [Homburg preconditioning protocol (HPP)], including pentoxyphylline, glycine, deferoxamine, N-acetylcysteine, erythropoietin, melatonin, and simvastatin. A second SL group (SL-Con; n = 8) received NaCl. Untreated non-SL served as controls (Sham; n = 8). Cytokines release, leukocyte invasion, endothelial activation and liver morphology were studied directly after liver harvest and after 8 h cold storage. Lung tissue was studied to determine remote injury.

RESULTS

The SL-procedure induced an increase of TNF-α concentration, intercellular-adhesion-molecule 1 (ICAM-1) expression, leukocytic-tissue infiltration and vacuolization. This was associated with an increased number of apoptotic hepatocytes. HPP reduced TNF-α release, ICAM-1 expression, the number of infiltrated leukocytes, as well as hepatocellular vacuolization and apoptosis. In lung tissue, the SL-procedure caused an increased IL-1 and IL-6 concentration and leukocyte infiltration.

CONCLUSIONS

HPP was capable of abrogating cytokine-mediated leukocytic response. Pharmacologic preconditioning of liver donors prevents the SL procedure-mediated inflammatory response, resulting in an improved graft quality.

The multifaceted role of pirfenidone and its novel targets

BACKGROUND

Pirfenidone (PFD) is a molecule that exhibits antifibrotic properties in a variety of in vitro and animal models of lung, liver and renal fibrosis. These pathologies share many fibrogenic pathways with an abnormal fibrous wound-healing process; consequently, tissue repair and tissue regeneration-regulating mechanisms are altered.

OBJECTIVE

To investigate the usefulness of PFD as an antifibrotic agent in clinical and experimental models of fibrotic disease.

CONCLUSIONS

There is a growing understanding of the molecular effects of PFD on the wound healing mechanism, leading to novel approaches for the management of fibrosis in lung, liver and renal tissues. Although the optimum treatment for fibrosis remains undefined, it is possible that combined therapeutic regimens that include this wide-application molecule, pirfenidone, could offer a useful treatment for fibrotic disease.

Fluorofenidone attenuates collagen I and transforming growth factor-beta1 expression through a nicotinamide adenine dinucleotide phosphate oxidase-dependent way in NRK-52E cells

AIM

Fluorofenidone (1-(3-fluorophenyl)-5-methyl-2-(1H)-pyridone) is a novel pyridone agent. The aim of the present study is to investigate the effects of fluorofenidone on angiotensin (Ang)II-induced fibrosis and the involved molecular mechanism in rat proximal tubular epithelial cells.

METHODS

NRK-52E cells, a rat proximal tubular epithelial cell line, were incubated with medium containing AngII, with or without nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor diphenylene iodonium (DPI), losartan, fluorofenidone (2, 4 and 8 mmol/L) and pirfenidone (8 mmol/L) for 24 h. Cells in the serum-free medium were controls. The expression of three subunits of NADPH oxidase, including p47phox, Nox-4 and p22phox, were determined by real-time reverse transcription polymerase chain reaction (RT-PCR) and western blot. NADPH oxidase activity was measured directly by superoxide dismutase (SOD) inhibitable cytochrome C reduction assay. The generation of reactive oxygen species (ROS) was measured by dichlorofluorescein fluorescence analysis. The mRNA and protein expression of collagen I and transforming growth factor (TGF)-beta1 were determined by real-time RT-PCR and enzyme-linked immunosorbent assay.

RESULTS

Fluorofenidone significantly inhibited TGF-beta1 and collagen I expression upregulation induced by AngII or TGF-beta1 respectively. Moreover, fluorofenidone greatly reduced the elevation of expression and activity of NADPH oxidase and inhibited ROS generation induced by AngII in rat proximal tubular epithelial cells. These responses were also attenuated by DPI, losartan, and pirfenidone.

CONCLUSION

Fluorofenidone acted as an anti-oxidative and anti-fibrotic agent through the mechanisms of blocking NADPH oxidase-dependent oxidative stress and inhibiting TGF-beta1 expression in rat proximal tubular epithelial cells.

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.

Reduced cytotoxic function of effector CD8+ T cells is responsible for indoleamine 2,3-dioxygenase-dependent immune suppression

Indoleamine 2,3-dioxygenase (IDO), a potent immunosuppressive enzyme, contributes to tumoral escape, immune tolerance, and protection against allograft injury. In this paper, we report that inhibition of CD8(+) T cell-mediated cytotoxic function is an important mechanism behind IDO's immune-modulating property. The experimental rat lung allograft proved attractive for evaluating effector CD8(+) T cells. Enhanced IDO activity achieved by using a lung-tissue-targeted nonviral human IDO gene transfer approach reduced, but did not eliminate, infiltrating CD8(+) T cells. Although CD8(+) T cells existed in the IDO-high lung allografts, CD8(+) T cells remained viable and could proliferate for an extended period. However, cells lost their ability to attack allogeneic donor lung cells in vivo and allogeneic target cells in vitro. The impaired cytotoxic function seen in the IDO-treated CD8(+) T cells was accompanied by defects in production of granule cytotoxic proteins, including perforin and granzyme A and B. Furthermore, we discovered that IDO leads to an impaired bioenergetic condition in active CD8(+) T cells via selective inhibition of complex I in the mitochondrial electron transfer chain. These intriguing findings provide a base for establishing a novel mode of IDO's immune-suppressing action. Additionally, donor lung IDO delivery, a direct and/or leukocyte passenger effect, impaired CD8(+) effector cell function.

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.

Nonviral gene delivery with indoleamine 2,3-dioxygenase targeting pulmonary endothelium protects against ischemia-reperfusion injury

Pulmonary endothelial dysfunction induced by inflammation and inflammation-associated reactive oxygen species is a central component in the pathophysiology of lung transplant ischemia-reperfusion (IR) injury. Indoleamine-2,3-dioxygenase (IDO) is a unique cytosolic enzyme possessing both immune modulating and antioxidant properties. This study investigated whether enhanced pulmonary endothelial IDO activity by a targeted nonviral gene transfer approach ameliorates lung IR injury. Orthotopic syngeneic lung transplants were performed in Lewis rats. A human IDO (hIDO)-expressing plasmid driven by an endothelial cell-specific endothelin-1 promoter was generated and intravenously delivered to donor lung using cationic polymer polyethylenimine. This nonviral gene transfer approach augmented hIDO expression specifically in endothelial cells within lung grafts. Importantly, enhanced IDO activity induced by the hIDO transgene prevented endothelial cell apoptosis, reduced vascular permeability and leukocyte extravasation, and consequently improved graft function and histologic appearance. Furthermore, our in vitro studies showed that increased IDO activity in endothelial cells protected its mitochondrial function and ultrastructure from oxidative stress through stabilization of intracellular redox status. The approach used in these experiments has properties that could eliminate the inherent side effects associated with viral vectors and/or antibody-directed targeted therapy, and thus may represent a potential therapeutic strategy against lung IR injury in patients.

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.

Therapeutic targets in the treatment of allograft fibrosis

The dramatic improvements in short-term graft survival and acute rejection rates could only have been dreamed of 20 years ago. Late graft loss following kidney transplantation is now the critical issue of this decade. Frequently, graft loss is associated with the development of tubular atrophy and interstitial fibrosis within the kidney (i.e. chronic allograft nephropathy; CAN). Major treatment strategies in this disorder are non-specific and the focus of intervention has been on limiting injurious events. Following graft injury is a fibrogenesis phase featuring both proliferative and infiltrative responses mediated by chemokines, cytokines and growth factors. In particular, TGFbeta has been strongly implicated in the pathogenesis of chronic injury and epithelial-mesenchymal transformation (EMT) may be part of this process. The cascade of events results in matrix accumulation, due to either increased production and/or reduced degradation of matrix. Recent investigations into the pathogenesis of tissue fibrosis have suggested a number of new strategies to ameliorate matrix synthesis. While the majority of therapies have focused on TGFbeta, this may not be an ideal maneuver in transplant settings and alternative targets identified in other fibrotic diseases will be discussed. Attacking graft fibrosis should be a new focus in organ transplantation.

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.

Novel Action of Indoleamine 2,3-Dioxygenase Attenuating Acute Lung Allograft Injury

RATIONALE

Lung allografts are prone to reperfusion injury and acute rejection, which, in addition to infiltrating lymphocytes, are accompanied by neutrophil infiltration and neutrophil-associated oxidative stress. Indoleamine 2,3-dioxygenase (IDO) is a unique cytosolic enzyme that possesses T-cell-suppressive and antioxidant properties.

OBJECTIVES

The purpose of this study was to determine if genetic up-regulation of IDO could ameliorate acute lung allograft injury.

METHODS

Lung orthotopic transplants were performed using Lewis donors and Sprague-Dawley rat recipients (allografts) or the same strain (isografts). Plasmid-encoding human IDO was delivered to donor lungs in vivo using a nonviral gene-transfer vector, polyethylenimine. Transplanted lungs were evaluated at 6 d post-transplantation based on pulmonary function, histology, inflammatory responses, and their associated oxidative stress. Basic biology of the IDO-overexpressing lung cells was evaluated in vitro in response to external oxidant.

MEASUREMENTS AND MAIN RESULTS

This gene delivery method led to uniform transgene expression in lung tissue distributed in airway, alveolar epithelial, and endothelial cells. IDO overexpression in lung allografts resulted in a significant protective effect with improvement in functional properties (peak airway pressure and oxygenation) and histologic appearance. Although IDO was able to block local T-cell responses, it failed to abrogate neutrophilic infiltration and the inflammation-associated oxidative stress. IDO-enhanced lung cells were resistance to oxidant-induced necrosis and apoptosis by limiting intracellular reactive oxygen species formation.

CONCLUSIONS

These results demonstrate that IDO prevents acute lung allograft injury through augmenting the local antioxidant defense system and inhibiting alloreactive T-cell responses.