Ziritaxestat, a Novel Autotaxin Inhibitor, and Lung Function in Idiopathic Pulmonary Fibrosis: The ISABELA 1 and 2 Randomized Clinical Trials.

Importance: There is a major need for effective, well-tolerated treatments for idiopathic pulmonary fibrosis (IPF). Objective: To assess the efficacy and safety of the autotaxin inhibitor ziritaxestat in patients with IPF. Design, Setting, and Participants: The 2 identically designed, phase 3, randomized clinical trials, ISABELA 1 and ISABELA 2, were conducted in Africa, Asia-Pacific region, Europe, Latin America, the Middle East, and North America (26 countries). A total of 1306 patients with IPF were randomized (525 patients at 106 sites in ISABELA 1 and 781 patients at 121 sites in ISABELA 2). Enrollment began in November 2018 in both trials and follow-up was completed early due to study termination on April 12, 2021, for ISABELA 1 and on March 30, 2021, for ISABELA 2. Interventions: Patients were randomized 1:1:1 to receive 600 mg of oral ziritaxestat, 200 mg of ziritaxestat, or placebo once daily in addition to local standard of care (pirfenidone, nintedanib, or neither) for at least 52 weeks. Main Outcomes and Measures: The primary outcome was the annual rate of decline for forced vital capacity (FVC) at week 52. The key secondary outcomes were disease progression, time to first respiratory-related hospitalization, and change from baseline in St George's Respiratory Questionnaire total score (range, 0 to 100; higher scores indicate poorer health-related quality of life). Results: At the time of study termination, 525 patients were randomized in ISABELA 1 and 781 patients in ISABELA 2 (mean age: 70.0 [SD, 7.2] years in ISABELA 1 and 69.8 [SD, 7.1] years in ISABELA 2; male: 82.4% and 81.2%, respectively). The trials were terminated early after an independent data and safety monitoring committee concluded that the benefit to risk profile of ziritaxestat no longer supported their continuation. Ziritaxestat did not improve the annual rate of FVC decline vs placebo in either study. In ISABELA 1, the least-squares mean annual rate of FVC decline was -124.6 mL (95% CI, -178.0 to -71.2 mL) with 600 mg of ziritaxestat vs -147.3 mL (95% CI, -199.8 to -94.7 mL) with placebo (between-group difference, 22.7 mL [95% CI, -52.3 to 97.6 mL]), and -173.9 mL (95% CI, -225.7 to -122.2 mL) with 200 mg of ziritaxestat (between-group difference vs placebo, -26.7 mL [95% CI, -100.5 to 47.1 mL]). In ISABELA 2, the least-squares mean annual rate of FVC decline was -173.8 mL (95% CI, -209.2 to -138.4 mL) with 600 mg of ziritaxestat vs -176.6 mL (95% CI, -211.4 to -141.8 mL) with placebo (between-group difference, 2.8 mL [95% CI, -46.9 to 52.4 mL]) and -174.9 mL (95% CI, -209.5 to -140.2 mL) with 200 mg of ziritaxestat (between-group difference vs placebo, 1.7 mL [95% CI, -47.4 to 50.8 mL]). There was no benefit with ziritaxestat vs placebo for the key secondary outcomes. In ISABELA 1, all-cause mortality was 8.0% with 600 mg of ziritaxestat, 4.6% with 200 mg of ziritaxestat, and 6.3% with placebo; in ISABELA 2, it was 9.3% with 600 mg of ziritaxestat, 8.5% with 200 mg of ziritaxestat, and 4.7% with placebo. Conclusions and Relevance: Ziritaxestat did not improve clinical outcomes compared with placebo in patients with IPF receiving standard of care treatment with pirfenidone or nintedanib or in those not receiving standard of care treatment. Trial Registration: ClinicalTrials.gov Identifiers: NCT03711162 and NCT03733444.

Evaluation of VEGF-A and CCL2 in dogs with brachycephalic obstructive airway syndrome or canine idiopathic pulmonary fibrosis and in normocephalic dogs.

Brachycephalic obstructive airway syndrome (BOAS) and canine idiopathic pulmonary fibrosis (CIPF) of West Highland White Terriers (WHWTs) often cause intermittent or chronic hypoxemia. Our objective was to evaluate serum and bronchoalveolar lavage fluid (BALF) concentrations of hypoxemia-related proinflammatory mediators vascular endothelial growth factor A (VEGF-A) and chemokine (CC motif) ligand 2 (CCL2) in brachycephalic dogs (BDs) and WHWTs with and without CIPF. Additionally, effects of BOAS severity and ageing on these mediators were assessed. 114 BDs (28 English Bulldogs (EBs), 37 French Bulldogs, 49 Pugs), 16 WHWTs with CIPF, 26 healthy WHWTs, and 39 normocephalic control dogs were included. Fifty-four BDs were re-examined after two to three years. Bead-based immunoassay was used for proinflammatory mediator measurements. Compared with controls, significantly higher serum concentrations of VEGF-A were seen in EBs (P = 0.009) and of CCL2 in CIPF and healthy WHWTs (P < 0.001; P = 0.002). BALF samples were available from controls, EBs, and WHWTs. VEGF-A was significantly lower in EBs (P < 0.001) and in CIPF and healthy WHWTs (P = 0.006; P = 0.007) and CCL2 was higher in CIPF WHWTs (P = 0.01) compared with controls. Between visits, only serum VEGF-A significantly decreased in BDs (P < 0.001), but breed, BOAS severity, or its change had no significant effect. In conclusion, in EBs with BOAS proinflammatory changes in VEGF-A were detected in both serum and BALF. Ageing reduced serum VEGF-A in BDs. In WHWTs, our results confirmed earlier findings of CCL2 as an important biomarker for CIPF.

Seguimiento de 20 pacientes portadores de fibrosis pulmonar idiopática tratados con nintedanib / Follow-up of 20 patients with idiopathic pulmonary fibrosis treated with nintedanib

Se presenta un estudio observacional compasivo de seguimiento de 20 pacientes portadores de Fibrosis Pulmonar Idiopática tratados con Nintedanib, que muestra que Nintedanib es un medicamento en general bien tolerado, sin efectos adversos serios, que otorga una sobrevida más prolongada que la que cabría esperar en pacientes con esta enfermedad.

A compassionate observational follow-up study of 20 patients with Idiopathic Pulmonary Fibrosis treated with Nintedanib is presented, showing that Nintedanib is a generally well-tolerated drug, with no serious adverse effects, that grants a longer survival in real-life patients.

Trial of a Preferential Phosphodiesterase 4B Inhibitor for Idiopathic Pulmonary Fibrosis.

BACKGROUND: Phosphodiesterase 4 (PDE4) inhibition is associated with antiinflammatory and antifibrotic effects that may be beneficial in patients with idiopathic pulmonary fibrosis. METHODS: In this phase 2, double-blind, placebo-controlled trial, we investigated the efficacy and safety of BI 1015550, an oral preferential inhibitor of the PDE4B subtype, in patients with idiopathic pulmonary fibrosis. Patients were randomly assigned in a 2:1 ratio to receive BI 1015550 at a dose of 18 mg twice daily or placebo. The primary end point was the change from baseline in the forced vital capacity (FVC) at 12 weeks, which we analyzed with a Bayesian approach separately according to background nonuse or use of an antifibrotic agent. RESULTS: A total of 147 patients were randomly assigned to receive BI 1015550 or placebo. Among patients without background antifibrotic use, the median change in the FVC was 5.7 ml (95% credible interval, -39.1 to 50.5) in the BI 1015550 group and -81.7 ml (95% credible interval, -133.5 to -44.8) in the placebo group (median difference, 88.4 ml; 95% credible interval, 29.5 to 154.2; probability that BI 1015550 was superior to placebo, 0.998). Among patients with background antifibrotic use, the median change in the FVC was 2.7 ml (95% credible interval, -32.8 to 38.2) in the BI 1015550 group and -59.2 ml (95% credible interval, -111.8 to -17.9) in the placebo group (median difference, 62.4 ml; 95% credible interval, 6.3 to 125.5; probability that BI 1015550 was superior to placebo, 0.986). A mixed model with repeated measures analysis provided results that were consistent with those of the Bayesian analysis. The most frequent adverse event was diarrhea. A total of 13 patients discontinued BI 1015550 treatment owing to adverse events. The percentages of patients with serious adverse events or severe adverse events were similar in the two trial groups. CONCLUSIONS: In this placebo-controlled trial, treatment with BI 1015550, either alone or with background use of an antifibrotic agent, prevented a decrease in lung function in patients with idiopathic pulmonary fibrosis. (Funded by Boehringer Ingelheim; 1305-0013 ClinicalTrials.gov number, NCT04419506.).

DOCK2 contributes to pulmonary fibrosis by promoting lung fibroblast to myofibroblast transition.

Idiopathic pulmonary fibrosis (IPF) is the most common chronic interstitial lung disease and is characterized by progressive scarring of the lung. Transforming growth factor-ß (TGF-ß) signaling plays an essential role in IPF and drives fibroblast to myofibroblast transition (FMT). Dedicator of cytokinesis 2 (DOCK2) is known to regulate diverse immune functions by activating Rac and has been recently implicated in pleural fibrosis. We now report a novel role of DOCK2 in pulmonary fibrosis development by mediating FMT. In primary normal and IPF human lung fibroblasts (HLFs), TGF-ß induced DOCK2 expression concurrent with FMT markers, smooth muscle α-actin (α-SMA), collagen-1, and fibronectin. Knockdown of DOCK2 significantly attenuated TGF-ß-induced expression of these FMT markers. In addition, we found that the upregulation of DOCK2 by TGF-ß is dependent on both Smad3 and ERK pathways as their respective inhibitors blocked TGF-ß-mediated induction. TGF-ß also stabilized DOCK2 protein, which contributes to increased DOCK2 expression. In addition, DOCK2 was also dramatically induced in the lungs of patients with IPF and in bleomycin, and TGF-ß induced pulmonary fibrosis in C57BL/6 mice. Furthermore, increased lung DOCK2 expression colocalized with the FMT marker α-SMA in the bleomycin-induced pulmonary fibrosis model, implicating DOCK2 in the regulation of lung fibroblast phenotypic changes. Importantly, DOCK2 deficiency also attenuated bleomycin-induced pulmonary fibrosis and α-SMA expression. Taken together, our study demonstrates a novel role of DOCK2 in pulmonary fibrosis by modulating FMT and suggests that targeting DOCK2 may present a potential therapeutic strategy for the prevention or treatment of IPF.

An Acute Exacerbation of Idiopathic Pulmonary Fibrosis After BNT162b2 mRNA COVID-19 Vaccination: A Case Report.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by progressive scar tissue formation. An acute exacerbation of IPF (AE-IPF) is a clinically significant respiratory decompensation that accounts for a significant proportion of IPF-related morbidity and mortality. AE-IPF can be idiopathic or associated with pulmonary embolism, infection, aspiration, surgery, and drug toxicity. In this novel case report, we describe a potential association between AE-IPF and BNT162b2 mRNA COVID-19 vaccination that was successfully treated with a short course of glucocorticoids. While our aim is to raise awareness for this yet-to-be-described adverse event, immunization against vaccine-preventable disease remains widely recommended in vulnerable patients with chronic lung disease such as IPF.

Transient Agarose Spot (TAS) Assay: A New Method to Investigate Cell Migration.

Fibroblasts play a central role in diseases associated with excessive deposition of extracellular matrix (ECM), including idiopathic pulmonary fibrosis. Investigation of different properties of fibroblasts, such as migration, proliferation, and collagen-rich ECM production is unavoidable both in basic research and in the development of antifibrotic drugs. In the present study we developed a cost-effective, 96-well plate-based method to examine the migration of fibroblasts, as an alternative approach to the gold standard scratch assay, which has numerous limitations. This article presents a detailed description of our transient agarose spot (TAS) assay, with instructions for its routine application. Advantages of combined use of different functional assays for fibroblast activation in drug development are also discussed by examining the effect of nintedanib-an FDA approved drug against IPF-on lung fibroblasts.

The antifibrotic effect of pheretima protein is mediated by the TGF-ß1/Smad2/3 pathway and attenuates inflammation in bleomycin-induced idiopathic pulmonary fibrosis.

ETHNOPHARMACOLOGICAL RELEVANCE: Pheretima is a traditional Chinese medicine that could treat various lung diseases such as asthma, pneumonia, and lung cancer effectively; however, limited studies on the use of Pheretima protein in the treatment of lung diseases have been conducted to date. AIM OF THE STUDY: The aim of this study was to explain the antipulmonary fibrosis mechanism of the Pheretima protein and elucidate its possible cell signaling pathways. MATERIAL AND METHODS: Fresh pheretima was freeze-dried to obtain the Pheretima protein. Divide C57BL/6 mice into control and bleomycin (BLM)-induced models, pirfenidone, and Pheretima protein-treatment groups. Three weeks later, they were treated with H&E and Masson's trichrome staining to assess lung injury and fibrosis. Pulmonary fibrosis was assessed using immunohistochemistry (IHC), realtime-PCR (RT-PCR), and western blotting. Inflammation was assessed using the alveolar lavage fluid. RESULTS: Pheretima protein inhibited epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) deposition and reduced inflammation. It also reduced the levels of Smad2/3, pSmad2/3, and transforming growth factor-beta 1 (TGF-ß1). Thus, our results indicate that Pheretima protein can alleviate BLM-induced pulmonary fibrosis in a mouse model. CONCLUSION: Pheretima protein inhibits ECM, EMT, and antiinflammatory markers, which in turn ameliorates BLM-induced pulmonary fibrosis. Preliminary mechanistic studies indicated that Pheretima protein can exert its biological activity by downregulating the TGF-ß1/Smad2/3 pathway.

Effects of low-dose pirfenidone on survival and lung function decline in patients with idiopathic pulmonary fibrosis (IPF): Results from a real-world study.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing interstitial pneumonia of unknown etiology. In several randomized clinical trials, and in the clinical practice, pirfenidone is used to effectively and safely treat IPF. However, sometimes it is difficult to use the dose of pirfenidone used in clinical trials. This study evaluated the effects of low-dose pirfenidone on IPF disease progression and patient survival in the real-world. METHODS: This retrospective, observational study enrolled IPF patients seen at the time of diagnosis at a single center from 2008 to 2018. Longitudinal clinical and laboratory data were prospectively collected. We compared the clinical characteristics, survival, and pulmonary function decline between patients treated and untreated with various dose of pirfenidone. RESULTS: Of 295 IPF patients, 100 (33.9%) received pirfenidone and 195 (66.1%) received no antifibrotic agent. Of the 100 patients who received pirfenidone, 24 (24%), 50 (50%), and 26 (26%), respectively, were given 600, 1200, and 1800 mg pirfenidone daily. The mean survival time was 57.03 ± 3.90 months in the no-antifibrotic drug group and 73.26 ± 7.87 months in the pirfenidone-treated group (p = 0.027). In the unadjusted analysis, the survival of the patients given pirfenidone was significantly better (hazard ratio [HR] = 0.69, 95% confidence interval [CI]: 0.48-0.99, p = 0.04). After adjusting for age, gender, body mass index, and the GAP score [based on gender (G), age (A), and two physiological lung parameters (P)], survival remained better in the patients given pirfenidone (HR = 0.56, 95% CI: 0.37-0.85, p = 0.006). In terms of pulmonary function, the decreases in forced vital capacity (%), forced expiratory volume in 1 s (%) and the diffusing capacity of lung for carbon monoxide (%) were significantly smaller (p = 0.000, p = 0.001, and p = 0.007, respectively) in patients given pirfenidone. CONCLUSIONS: Low-dose pirfenidone provided beneficial effects on survival and pulmonary function decline in the real-world practice.

Real-life prevalence of progressive fibrosing interstitial lung diseases.

The concept of progressive fibrosing interstitial lung disease (PF-ILD) has recently emerged. However, real-life proportion of PF-ILDs outside IPF is still hard to evaluate. Therefore, we sought to estimate the proportion of PF-ILD in our ILD cohort. We also determined the proportion of ILD subtypes within PF-ILD and investigated factors associated with PF-ILDs. Finally, we quantified interobserver agreement between radiologists for the assessment of fibrosis. We reviewed the files of ILD patients discussed in multidisciplinary discussion between January 1st 2017 and December 31st 2019. Clinical data, pulmonary function tests (PFTs) and high-resolution computed tomography (HRCTs) were centrally reviewed. Fibrosis was defined as the presence of traction bronchiectasis, reticulations with/out honeycombing. Progression was defined as a relative forced vital capacity (FVC) decline of ≥ 10% in ≤ 24 months or 5% < FVC decline < 10% and progression of fibrosis on HRCT in ≤ 24 months. 464 consecutive ILD patients were included. 105 had a diagnosis of IPF (23%). Most frequent non-IPF ILD were connective tissue disease (CTD)-associated ILD (22%), hypersensitivity pneumonitis (13%), unclassifiable ILD (10%) and sarcoidosis (8%). Features of fibrosis were common (82% of CTD-ILD, 81% of HP, 95% of uILD). After review of HRCTs and PFTs, 68 patients (19% of non-IPF ILD) had a PF-ILD according to our criteria. Interobserver agreement for fibrosis between radiologists was excellent (Cohen's kappa 0.86). The main diagnosis among PF-ILD were CTD-ILD (36%), HP (22%) and uILD (20%). PF-ILD patients were significantly older than non-F-ILD (P = 0.0005). PF-ILDs represent about 20% of ILDs outside IPF. This provides an estimation of the proportion of patients who might benefit from antifibrotics. Interobserver agreement between radiologists for the diagnosis of fibrotic ILD is excellent.

Development of a nomogram for predicting the presence of combined pulmonary fibrosis and emphysema.

BACKGROUND: In the clinical management of patients with combined pulmonary fibrosis and emphysema (CPFE), early recognition and appropriate treatment is essential. This study was designed to develop an accurate prognostic nomogram model to predict the presence of CPFE. METHODS: We retrospectively enrolled 85 patients with CPFE and 128 patients with idiopathic pulmonary fibrosis (IPF) between January 2015 and January 2020. Clinical characteristics were compared between groups. A multivariable logistic regression analysis was performed to identify risk factors for CPFE. Then, and a nomogram to predict the presence of CPFE was constructed for clinical use. Concordance index (C-index), area under the receiver operating characteristic curve (AUC), and calibration plot was used to evaluate the efficiency of the nomogram. RESULTS: Compared to the IPF group, the proportion of patients with male, smoking and allergies were significantly higher in the CPFE group. In terms of pulmonary function tests, patients with CPFE had lower FEV1/FVC%, DLCO/VA% pred, and higher RV, RV%pred, VC, VC%pred, TLC%pred, VA, TLC, TLC%pred, FVC, FVC%pred and FEV1 with significant difference than the other group. Positive correlation was found between DLCO and VA%, RV%, TLC% in patients with IPF but not in patients with CPFE. By multivariate analysis, male, smoking, allergies, FEV1/FVC% and DLCO/VA%pred were identified as independent predictors of the presence of CPFE. The nomogram was then developed using these five variables. After 1000 internal validations of bootstrap resampling, the C-index of the nomogram was 0.863 (95% CI 0.795-0.931) and the AUC was 0.839 (95% CI 0.764-0.913). Moreover, the calibration plot showed good concordance of incidence of CPFE between nomogram prediction and actual observation (Hosmer-Lemeshow test: P = 0.307). CONCLUSIONS: Patients of CPFE have a characteristic lung function profile including relatively preserved lung volumes and ventilating function, contrasting with a disproportionate reduction of carbon monoxide transfer. By incorporating clinical risk factors, we created a nomogram to predict the presence of CPFE, which may serve as a potential tool to guide personalized treatment.

Feasibility and safety of treatment switch from Pirfenidone to Nintedanib in patients with idiopathic pulmonary fibrosis: a real-world observational study.

OBJECTIVE: Idiopathic Pulmonary Fibrosis is a disease characterized by a devastating fibrosing process. Two anti-fibrotic agents, pirfenidone and nintedanib, have been found to alter the disease progression. In this study, we sought to determine whether switching treatment to nintedanib is feasible and safe in patients that had to discontinue treatment with pirfenidone due to side effects. PATIENTS AND METHODS: We analyzed patients that had to discontinue pirfenidone due to side effects. Patients were prospectively enrolled for treatment with nintedanib between March 2015 and June 2019. Side effects and Pulmonary Function Tests were recorded. RESULTS: 12 patients received nintedanib after discontinuing treatment with pirfenidone. Side-effects that led to discontinuation were diarrhea (33.3%), nausea (16.6%), photosensitivity (33.3%) and difficulty adhering to pirfenidone's dosage scheme (16.6%). After the initiation of nintedanib, diarrhea was the most common side effect (66.6%). Four patients of these patients could not tolerate the full dose of 300 mg daily and had to reduce it to 200 mg daily. No patient has had experienced liver damage. During the last twelve months of treatment with pirfenidone, mean ΔFCV was +2.47 ± 3.69%, mean ΔDLco was -0.36 ± 2.64% and mean difference of the distance walked during the 6MWT was 5 ± 56.48 meters. During the first year of treatment with nintedanib, mean ΔFCV was -1.32 ± 1.12% (p=0.68), mean ΔDLco was -1.59 ± 3.45% (p=0.54) and mean difference of the distance walked during the 6MWT was 14.17 ± 59 meters (p=0.078). 50% of patients had stable disease under pirfenidone (6-month FVC decline < 5% and/or 6-month DLco decline < 10%) vs. 50% under nintedanib, 33.3% had marginal 6-month decline (5% ≤ 6-month FVC ≤ 10% and/or (≤ 10% 6- month DLco decline ≤15%) under pirfenidone vs. 33.3% under nintedanib and 16.6% had disease progression (6-month FVC decline > 10% and/or 6-month DLco decline > 15%) under pirfenidone vs. 16.6% under nintedanib. CONCLUSIONS: These results suggest that nintedanib is a safe option for the treatment of patients that had to discontinue pirfenidone due to adverse reactions. Further studies with greater patient numbers are needed for accurate results concerning efficacy.

Progressive fibrosis in interstitial lung diseases - proposed definition and management.

Interstitial lung diseases may have an unpredictably progressive course, which is manifested as progression of pulmonary fibrosis, causing an increasing impairment of lung function affecting a poor prognosis. The possibility of an effective antifibrotic treatment is a chance for patients to slow down the progression of the disease, perhaps even extend their life. For this reason, standardization of the definition as well as identification criteria for progressive fibrosis interstitial lung disease is a method for optimizing the management in this group of patients.

Longitudinal serological assessment of type VI collagen turnover is related to progression in a real-world cohort of idiopathic pulmonary fibrosis.

BACKGROUND: Remodeling of the extracellular matrix (ECM) is a central mechanism in the progression of idiopathic pulmonary fibrosis (IPF), and remodeling of type VI collagen has been suggested to be associated with disease progression. Biomarkers that reflect and predict the progression of IPF would provide valuable information for clinicians when treating IPF patients. METHODS: Two serological biomarkers reflecting formation (PRO-C6) and degradation (C6M) of type VI collagen were evaluated in a real-world cohort of 178 newly diagnoses IPF patients. All patients were treatment naïve at the baseline visit. Blood samples and clinical data were collected from baseline, six months, and 12 months visit. The biomarkers were measured by competitive ELISA using monoclonal antibodies. RESULTS: Patients with progressive disease had higher (P = 0.0099) serum levels of PRO-C6 compared to those with stable disease over 12 months with an average difference across all timepoints of 12% (95% CI 3-22), whereas C6M levels tended (P = 0.061) to be higher in patients with progressive disease compared with stable patients over 12 months with an average difference across all timepoints of 12% (95% CI - 0.005-27). Patients who did not receive antifibrotic medicine had a greater increase of C6M (P = 0.043) compared to treated patients from baseline over 12 months with an average difference across all timepoints of 12% (95% CI - 0.07-47). There were no differences in biomarker levels between patients receiving pirfenidone or nintedanib. CONCLUSIONS: Type VI collagen formation was related to progressive disease in patients with IPF in a real-world cohort and antifibrotic therapy seemed to affect the degradation of type VI collagen. Type VI collagen formation and degradation products might be potential biomarkers for disease progression in IPF.

Curcumin inhibition of bleomycin-induced changes in lung collagen synthesis, deposition and assembly.

BACKGROUND: Idiopathic pulmonary fibrosis is characterized by progressive lung tissue remodeling and disproportionate deposition of collagenous proteins with limited therapeutic interventions. The purpose of this study was to determine whether curcumin inhibits bleomycin (BLM)-induced increases in synthesis, degradation and cross-linking of lung collagen in rats. METHODS AND RESULTS: Following a single intratracheal instillation of BLM to rats (0.75 U/100 g, sacrificed 3, 5, 7, 14 and 28 days post-BLM), lung collagen synthesis (determined by incorporation of 3H-proline) and deposition (determined by lung hydroxyproline content) progressively increased at days 7, 14 and 28 post-BLM injection. Lung lavage fluid hydroxyproline and collagenase levels (a measure of collagen turnover) were increased in BLM rats compared with control groups. In addition, BLM instillation resulted in increased concentrations of collagenase and collagenolytic cathepsin in the lungs. Furthermore, increased cross-linking (as determined by aldehyde content of acid soluble collagen), and decreased susceptibility of fibrotic lung insoluble collagen to denaturing agents occurred in BLM-injured lungs. Significant increases in alveolar macrophage (AM) release of transforming growth factor-ß1 (TGF-ß1) were noted at various time points (days 3, 5, 7, 14 and 28 post-BLM) during the development and progression of lung fibrosis in rats. Curcumin treatment to BLM rats (300 mg/kg 10 days before and daily thereafter throughout the experimental time period) was associated with marked reductions in lung collagen synthesis and deposition, BALF and lung collagenase activity, BALF hydroxyproline content and lung collagenolytic levels. Additionally, reduced levels of collagen cross-linking and enhanced susceptibility of insoluble lung collagen to denaturing agents were observed in curcumin-treated BLM rats. Finally, curcumin inhibited BLM-induced increases in AM production of TGF-ß1. CONCLUSIONS: Our data demonstrate for the first time that curcumin prevents fibrotic deposits by modulating collagen turnover, assembly and deposition in BLM-instilled rat lungs, and that curcumin treatment protects against BLM activation of macrophages by suppressing the release of TGF-ß1.