Vascular dysfunction by myofibroblast activation in patients with idiopathic pulmonary fibrosis and prognostic significance

In this study, we demonstrated the importance of telomerase protein expression and determined the relationships among telomerase, endothelin-1 (ET-1) and myofibroblasts during early and late remodeling of parenchymal and vascular areas in usual interstitial pneumonia (UIP) using 27 surgical lung biopsies from patients with idiopathic pulmonary fibrosis (IPF). Telomerase+, myofibroblasts alpha-SMA+, smooth muscle cells caldesmon+, endothelium ET-1+ cellularity, and fibrosis severity were evaluated in 30 fields covering normal lung parenchyma, minimal fibrosis (fibroblastic foci), severe ( mural) fibrosis, and vascular areas of UIP by the point-counting technique and a semiquantitative score. The impact of these markers was determined in pulmonary functional tests and follow-up until death from IPF. Telomerase and ET-1 expression was significantly increased in normal and vascular areas compared to areas of fibroblast foci. Telomerase and ET-1 expression was inversely correlated with minimal fibrosis in areas of fibroblast foci and directly associated with severe fibrosis in vascular areas. Telomerase activity in minimal fibrosis areas was directly associated with diffusing capacity of the lung for oxygen/alveolar volume and ET-1 expression and indirectly associated with diffusing capacity of the lungs for carbon monoxide and severe fibrosis in vascular areas. Cox proportional hazards regression revealed a low risk of death for females with minimal fibrosis displaying high telomerase and ET-1 expression in normal areas. Vascular dysfunction by telomerase/ET-1 expression was found earlier than vascular remodeling by myofibroblast activation in UIP with impact on IPF evolution, suggesting that strategies aimed at preventing the effect of these mediators may have a greater impact on patient outcome.

Increased fibroblast telomerase expression precedes myofibroblast alpha-smooth muscle actin expression in idiopathic pulmonary fibrosis

OBJECTIVE: This study sought to identify the relationship between fibroblast telomerase expression, myofibroblasts, and telomerase-mediated regulatory signals in idiopathic pulmonary fibrosis. METHODS: Thirty-four surgical lung biopsies, which had been obtained from patients with idiopathic pulmonary fibrosis and histologically classified as usual interstitial pneumonia, were examined. Immunohistochemistry was used to evaluate fibroblast telomerase expression, myofibroblast alpha-smooth muscle actin expression and the tissue expression of interleukin-4, transforming growth factor-beta, and basic fibroblast growth factor. The point-counting technique was used to quantify the expression of these markers in unaffected, collapsed, mural fibrosis, and honeycombing areas. The results were correlated to patient survival. RESULTS: Fibroblast telomerase expression and basic fibroblast growth factor tissue expression were higher in collapsed areas, whereas myofibroblast expression and interleukine-4 tissue expression were higher in areas of mural fibrosis. Transforming growth factor-beta expression was higher in collapsed, mural fibrosis and honeycombing areas in comparison to unaffected areas. Positive correlations were found between basic fibroblast growth factor tissue expression and fibroblast telomerase expression and between interleukin-4 tissue expression and myofibroblast alpha-smooth muscle actin expression. Negative correlations were observed between interleukin-4 expression and basic fibroblast growth factor tissue expression in areas of mural fibrosis. Myofibroblast alpha-smooth muscle actin expression and interleukin-4 tissue expression in areas of mural fibrosis were negatively associated with patient survival. CONCLUSION: Fibroblast telomerase expression is higher in areas of early remodeling in lung tissues demonstrating typical interstitial pneumonia, whereas myofibroblast alpha-smooth muscle actin expression predominates in areas of late remodeling. These events seem to be regulated by basic fibroblast growth factor and interleukin-4 tissue expression, respectively.

Increased fibroblast telomerase expression precedes myofibroblast α-smooth muscle actin expression in idiopathic pulmonary fibrosis

OBJECTIVE: This study sought to identify the relationship between fibroblast telomerase expression, myofibroblasts, and telomerase-mediated regulatory signals in idiopathic pulmonary fibrosis. METHODS: Thirty-four surgical lung biopsies, which had been obtained from patients with idiopathic pulmonary fibrosis and histologically classified as usual interstitial pneumonia, were examined. Immunohistochemistry was used to evaluate fibroblast telomerase expression, myofibroblast α-smooth muscle actin expression and the tissue expression of inter leu kin-4, transforming growth factor-β, and basic fibroblast growth factor. The point-counting technique was used to quantify the expression of these markers in unaffected, collapsed, mural fibrosis, and honeycombing areas. The results were correlated to patient survival. RESULTS: Fibroblast telomerase expression and basic fibroblast growth factor tissue expression were higher in collapsed areas, whereas myofibroblast expression and interleukine-4 tissue expression were higher in areas of mural fibrosis. Transforming growth factor-β expression was higher in collapsed, mural fibrosis and honeycombing areas in comparison to unaffected areas. Positive correlations were found between basic fibroblast growth factor tissue expression and fibroblast telomerase expression and between interleukin-4 tissue expression and myofibroblast α-smooth muscle actin expression. Negative correlations were observed between interleukin-4 expression and basic fibroblast growth factor tissue expression in areas of mural fibrosis. Myofibroblast α-smooth muscle actin expression and interleukin-4 tissue expression in areas of mural fibrosis were negatively associated with patient survival. CONCLUSION: Fibroblast telomerase expression is higher in areas of early remodeling in lung tissues demonstrating typical interstitial pneumonia, whereas myofibroblast α-smooth muscle actin expression predominates in areas of late remodeling. These events seem to be regulated by basic fibroblast growth factor and interleukin-4 tissue expression, respectively.

Pirfenidone in patients with idiopathic pulmonary fibrosis (CAPACITY): two randomised trials

Background Idiopathic pulmonary fibrosis is a progressive and fatal lung disease with inevitable loss of lung function. The CAPACITY programme (studies 004 and 006) was designed to confirm the results of a phase 2 study that suggested that pirfenidone, a novel antifibrotic and anti-inflammatory drug, reduces deterioration in lung function in patients with idiopathic pulmonary fibrosis. Methods In two concurrent trials (004 and 006), patients (aged 40–80 years) with idiopathic pulmonary fibrosis were randomly assigned to oral pirfenidone or placebo for a minimum of 72 weeks in 110 centres in Australia, Europe, and North America. In study 004, patients were assigned in a 2:1:2 ratio to pirfenidone 2403 mg/day, pirfenidone 1197 mg/day, or placebo; in study 006, patients were assigned in a 1:1 ratio to pirfenidone 2403 mg/day or placebo. The randomisation code (permuted block design) was computer generated and stratified by region. All study personnel were masked to treatment group assignment until after final database lock. Treatments were administered orally, 801 mg or 399 mg three times a day. The primary endpoint was change in percentage predicted forced vital capacity (FVC) at week 72. Analysis was by intention to treat. The studies are registered with ClinicalTrials.gov, numbers NCT00287729 and NCT00287716. Findings In study 004, 174 of 435 patients were assigned to pirfenidone 2403 mg/day, 87 to pirfenidone 1197 mg/day, and 174 to placebo. In study 006, 171 of 344 patients were assigned to pirfenidone 2403 mg/day, and 173 to placebo. All patients in both studies were analysed. In study 004, pirfenidone reduced decline in FVC (p=0·001). Mean FVC change at week 72 was −8·0% (SD 16·5) in the pirfenidone 2403 mg/day group and −12·4% (18·5) in the placebo group (difference 4·4%, 95% CI 0·7 to 9·1); 35 (20%) of 174 versus 60 (35%) of 174 patients, respectively, had a decline of at least 10%. A significant treatment effect was noted at all timepoints from week 24 and in an analysis over all study timepoints (p=0·0007). Mean change in percentage FVC in the pirfenidone 1197 mg/day group was intermediate to that in the pirfenidone 2403 mg/day and placebo groups. In study 006, the difference between groups in FVC change at week 72 was not significant (p=0·501). Mean change in FVC at week 72 was −9·0% (SD 19·6) in the pirfenidone group and −9·6% (19·1) in the placebo group, and the difference between groups in predicted FVC change at week 72 was not significant (0·6%, −3·5 to 4·7); however, a consistent pirfenidone effect was apparent until week 48 (p=0·005) and in an analysis of all study timepoints (p=0·007). Patients in the pirfenidone 2403 mg/day group had higher incidences of nausea (125 [36%] of 345 vs 60 [17%] of 347), dyspepsia (66 [19%] vs 26 [7%]), vomiting (47 [14%] vs 15 [4%]), anorexia (37 [11%] vs 13 [4%]), photosensitivity (42 [12%] vs 6 [2%]), rash (111 [32%] vs 40 [12%]), and dizziness (63 [18%] vs 35 [10%]) than did those in the placebo group. Fewer overall deaths (19 [6%] vs 29 [8%]) and fewer deaths related to idiopathic pulmonary fibrosis (12 [3%] vs 25 [7%]) occurred in the pirfenidone 2403 mg/day groups than in the placebo groups. Interpretation The data show pirfenidone has a favourable benefit risk profile and represents an appropriate treatment option for patients with idiopathic pulmonary fibrosis.

Increased uptake of 111In-octreotide in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by an uncontrolled accumulation and activation of lung fibroblasts. A modulation of fibroblast activation has been observed in various systems with octreotide, a synthetic somatostatin analog with strong affinity for the somatostatin receptor subtype 2 (sst2). One aim of our study was to evaluate the expression of somatostatin receptors in the lungs of patients with IPF. A second aim was to evaluate the relationship between 111In-octreotide uptake and the effect of pulmonary fibrosis as assessed by lung function tests and parameters and by radiologic findings. METHODS: We investigated 11 patients with IPF, 6 patients with pulmonary fibrosis associated with systemic sclerosis (SSc), and 19 patients with disease not of the lung (control patients). The expression of somatostatin receptors was evaluated in vivo using 111In-octreotide scintigraphy. We evaluated the relationship between 111In-octreotide uptake and the activity of pulmonary fibrosis as assessed by lung function tests, bronchoalveolar lavage (BAL) cellularity, and high-resolution CT (HRCT) of the chest. Planar images and thoracic SPECT (24 h) were performed after injection of 222 MBq of 111In-octreotide. Lung uptake was quantified using the lung-to-background ratio (L/B). In addition, the expression of sst2 was evaluated in vitro, in frozen lung-tissue samples using autoradiography, and in human cultures of lung fibroblasts using a ligand-binding assay. RESULTS: Compared with lung uptake in control patients (median L/B, 1.25; range, 1.14-1.49), lung uptake was increased in all 11 IPF patients (median L/B, 2.63; range, 1.59-3.13; P < 0.001) and in 4 of 6 SSc patients (median L/B, 1.68; range, 1.42-2.16). The L/B was lower in SSc patients than in IPF patients (P = 0.011). Increased uptake correlated with the alteration of lung function (carbon monoxide diffusing capacity [rho = -0.655; P = 0.038], diffusing capacity for carbon monoxide and alveolar volume ratio [rho = -0.627; P = 0.047], vital capacity [rho = -0.609; P = 0.054], and total lung capacity [rho = -0.598; P = 0.058]) and with the intensity of alveolitis (total BAL cellularity [rho = 0.756; P = 0.045], neutrophil counts [rho = 0.738; P = 0.05]), and HRCT fibrosis score (rho = 0.673; P = 0.007). Autoradiography suggested that vascular structures were a prominent binding site. Lung fibroblasts expressed somatostatin receptors in vitro as measured by binding assay. CONCLUSION: Our preliminary results identified an increased expression of sst2 in (mainly idiopathic) pulmonary fibrosis. Lung uptake correlates with the alteration of lung function and with the intensity of alveolitis.

Gastroesophageal reflux and pulmonary fibrosis in scleroderma: a study using pH-impedance monitoring

RATIONALE: Interstitial lung disease (ILD) in patients with systemic sclerosis (SSc) is associated with increased morbidity and mortality. Gastroesophageal reflux (GER) is considered a contributing factor in the pathogenesis of ILD. OBJECTIVES: To characterize GER (acid and nonacid) in patients with SSc with and without ILD. METHODS: Patients with SSc underwent pulmonary high-resolution computer tomography (HRCT) scan and 24-hour impedance-pH monitoring off-proton pump inhibitor therapy. The presence of pulmonary fibrosis was assessed using validated HRCT-scores. Reflux monitoring parameters included number of acid and nonacid reflux episodes, proximal migration of the refluxate, and distal esophageal acid exposure. Unless otherwise specified, data are presented as median (25th-75th percentile). MEASUREMENTS AND MAIN RESULTS: Forty consecutive patients with SSc (35 female; mean age, 53 yr; range, 24-71; 15 patients with diffuse and 25 with limited SSc) were investigated; 18 (45%) patients with SSc had pulmonary fibrosis (HRCT score >or= 7). Patients with SSc with ILD had higher (P < 0.01) esophageal acid exposure (10.3 [7.5-15] vs. 5.2 [1.5-11]), higher (P < 0.01) number of acid (41 [31-58] vs. 19 [10-23]) and nonacid (25 [20-35] vs. 17 [11-19]) reflux episodes, and higher (P < 0.01) number of reflux episodes reaching the proximal esophagus (42.5 [31-54] vs. 15 [8-22]) compared with patients with SSc with normal HRCT scores. Pulmonary fibrosis scores (HRCT score) correlated well with the number of reflux episodes in the distal (r(2) = 0.637) and proximal (r(2) = 0.644) esophagus. CONCLUSIONS: Patients with SSc with ILD have more severe reflux (i.e., more reflux episodes and more reflux reaching the proximal esophagus). Whether or not the development of ILD in patients with SSc can be prevented by reflux-reducing treatments needs to be investigated.

Treatment of idiopathic pulmonary fibrosis with ambrisentan: a parallel, randomized trial

BACKGROUND Idiopathic pulmonary fibrosis (IPF) is characterized by formation and proliferation of fibroblast foci. Endothelin-1 induces lung fibroblast proliferation and contractile activity via the endothelin A (ETA) receptor. OBJECTIVE To determine whether ambrisentan, an ETA receptor-selective antagonist, reduces the rate of IPF progression. DESIGN Randomized, double-blind, placebo-controlled, event-driven trial. (ClinicalTrials.gov: NCT00768300). SETTING Academic and private hospitals. PARTICIPANTS Patients with IPF aged 40 to 80 years with minimal or no honeycombing on high-resolution computed tomography scans. INTERVENTION Ambrisentan, 10 mg/d, or placebo. MEASUREMENTS Time to disease progression, defined as death, respiratory hospitalization, or a categorical decrease in lung function. RESULTS The study was terminated after enrollment of 492 patients (75% of intended enrollment; mean duration of exposure to study medication, 34.7 weeks) because an interim analysis indicated a low likelihood of showing efficacy for the end point by the scheduled end of the study. Ambrisentan-treated patients were more likely to meet the prespecified criteria for disease progression (90 [27.4%] vs. 28 [17.2%] patients; P = 0.010; hazard ratio, 1.74 [95% CI, 1.14 to 2.66]). Lung function decline was seen in 55 (16.7%) ambrisentan-treated patients and 19 (11.7%) placebo-treated patients (P = 0.109). Respiratory hospitalizations were seen in 44 (13.4%) and 9 (5.5%) patients in the ambrisentan and placebo groups, respectively (P = 0.007). Twenty-six (7.9%) patients who received ambrisentan and 6 (3.7%) who received placebo died (P = 0.100). Thirty-two (10%) ambrisentan-treated patients and 16 (10%) placebo-treated patients had pulmonary hypertension at baseline, and analysis stratified by the presence of pulmonary hypertension revealed similar results for the primary end point. LIMITATION The study was terminated early. CONCLUSION Ambrisentan was not effective in treating IPF and may be associated with an increased risk for disease progression and respiratory hospitalizations. PRIMARY FUNDING SOURCE Gilead Sciences.

The Role of IL-6 in Adenosine-Mediated Pulmonary Fibrosis

Adenosine is a purinergic signaling molecule that regulates various aspects of inflammation and has been implicated in the pathogenesis of chronic lung diseases. Previous studies have demonstrated that adenosine up-regulates IL-6 production through the engagement of the A2B adenosine receptor in various cell types, including alveolar macrophages. IL-6 is elevated in mouse models and humans with chronic lung disease, suggesting a potential role in disease progression. Furthermore, chronic elevation of adenosine in the lungs of adenosine deaminase deficient (Ada-/-) mice leads to the development of pulmonary inflammation, alveolar destruction, and fibrosis, in conjunction with IL-6 elevation. Thus, it was hypothesized that IL-6 contributes to pulmonary inflammation and fibrosis in this model. To test this hypothesis, Ada/IL-6 double knockout mice (Ada/IL-6-/-) were generated to assess the consequences of genetically removing IL-6 on adenosine-dependent pulmonary injury. Ada/IL-6-/- mice exhibited a significant reduction in inflammation, alveolar destruction, and pulmonary fibrosis. Next, Ada-/- mice were treated systematically with IL-6 neutralizing antibodies to test the efficacy of blocking IL-6 on chronic lung disease. These treatments were associated with decreased pulmonary inflammation, alveolar destruction, and fibrosis. To determine the role of IL-6 in a second model of pulmonary fibrosis, wild type mice and IL-6-/- mice were subjected to intraperitoneal injections of bleomycin twice a week for four weeks. Results demonstrated that IL-6-/- mice developed reduced pulmonary fibrosis. To examine a therapeutic approach in this model, wild type mice exposed to bleomycin were treated with IL-6 neutralizing antibodies. Similar results were observed as with Ada-/- mice, namely diminished pulmonary inflammation and fibrosis. In both models, elevations in IL-6 were associated with increased phosphorylated STAT-3 in the nuclei of numerous cell types in the airways, including type II alveolar epithelial cells (AEC). Genetic removal and neutralization of IL-6 in both models was associated with decreased STAT-3 activation in type II AEC. The mechanism of activation in these cells that lack the membrane bound IL-6Ra suggests IL-6 trans-signaling may play a role in regulating fibrosis. Characterization of this mechanism demonstrated that the soluble IL-6Ra (sIL-6Ra) is upregulated in both models during chronic conditions. In vitro studies in MLE-12 alveolar epithelial cells confirmed that IL-6, in combination with the sIL-6Ra, activates STAT-3 and TWIST in association with enhancement of epithelial-to-mesenchymal transition, which can contribute to fibrosis. Similarly, patients with idiopathic pulmonary fibrosis demonstrated a similar pattern of increased IL-6 expression, STAT-3 activation, and sIL-6Ra increases. These findings demonstrate that adenosine-dependent elevations in IL-6 contribute to the development and progression of pulmonary inflammation and fibrosis. The implications from these studies are that adenosine and/or IL-6 neutralizing agents represent novel therapeutic targets for the treatment of pulmonary disorders where fibrosis is a detrimental component.

Mouse models and quantitative trait loci of susceptibility to bleomycin- and radiation-induced pulmonary fibrosis

Radiotherapy involving the thoracic cavity and chemotherapy with the drug bleomycin are both dose limited by the development of pulmonary fibrosis. From evidence that there is variation in the population in susceptibility to pulmonary fibrosis, and animal data, it was hypothesized that individual variation in susceptibility to bleomycin-induced, or radiation-induced, pulmonary fibrosis is, in part, genetically controlled. In this thesis a three generation mouse genetic model of C57BL/6J (fibrosis prone) and C3Hf/Kam (fibrosis resistant) mouse strains and F1 and F2 (F1 intercross) progeny derived from the parental strains was developed to investigate the genetic basis of susceptibility to fibrosis. In the bleomycin studies the mice received 100 mg/kg (125 for females) of bleomycin, via mini osmotic pump. The animals were sacrificed at eight weeks following treatment or when their breathing rate indicated respiratory distress. In the radiation studies the mice were given a single dose of 14 or 16 Gy (Co$\sp{60})$ to the whole thorax and were sacrificed when moribund. The phenotype was defined as the percent of fibrosis area in the left lung as quantified with image analysis of histological sections. Quantitative trait loci (QTL) mapping was used to identify the chromosomal location of genes which contribute to susceptibility to bleomycin-induced pulmonary fibrosis in C57BL/6J mice compared to C3Hf/Kam mice and to determine if the QTL's which influence susceptibility to bleomycin-induced lung fibrosis in these progenitor strains could be implicated in susceptibility to radiation-induced lung fibrosis. For bleomycin, a genome wide scan revealed QTL's on chromosome 17, at the MHC, (LOD = 11.7 for males and 7.2 for females) accounting for approximately 21% of the phenotypic variance, and on chromosome 11 (LOD = 4.9), in male mice only, adding 8% of phenotypic variance. The bleomycin QTL on chromosome 17 was also implicated for susceptibility to radiation-induced fibrosis (LOD = 5.0) and contributes 7% of the phenotypic variance in the radiation study. In conclusion, susceptibility to both bleomycin-induced and radiation-induced pulmonary fibrosis are heritable traits, and are influenced by a genetic factor which maps to a genomic region containing the MHC. ^