JNK inhibition reduces lung remodeling and pulmonary fibrotic systemic markers

BACKGROUND

Lung remodeling and pulmonary fibrosis are serious, life-threatening conditions resulting from diseases such as chronic severe asthma and idiopathic pulmonary fibrosis (IPF). Preclinical evidence suggests that JNK enzyme function is required for key steps in the pulmonary fibrotic process. However, a selective JNK inhibitor has not been investigated in translational models of lung fibrosis with clinically relevant biomarkers, or in IPF patients.

METHODS

The JNK inhibitor CC-930 was evaluated in the house dust mite-induced fibrotic airway mouse model, in a phase I healthy volunteer pharmacodynamic study, and subsequently in a phase II multicenter study of mild/moderate IPF (n = 28), with a 4-week, placebo-controlled, double-blind, sequential ascending-dose period (50 mg QD, 100 mg QD, 100 mg BID) and a 52-week open-label treatment-extension period.

RESULTS

In the preclinical model, CC-930 attenuated collagen 1A1 gene expression, peribronchiolar collagen deposition, airway mucin MUC5B expression in club cells, and MMP-7 expression in lung, bronchoalveolar lavage fluid, and serum. In the phase I study, CC-930 reduced c-Jun phosphorylation induced by UV radiation in skin. In the phase II IPF study, there was a CC-930 dose-dependent trend in reduction of MMP-7 and SP-D plasma protein levels. The most commonly reported adverse events were increased ALT, increased AST, and upper respiratory tract infection (six subjects each, 21.4 %). A total of 13 subjects (46.4 %) experienced adverse events that led to discontinuation of study drug. Nine out of 28 subjects experienced progressive disease in this study. The mean FVC (% predicted) declined after 26-32 weeks at doses of 100 mg QD and 100 mg BID. Changes in MMP-7, SP-D, and tenascin-C significantly correlated with change in FVC (% predicted).

CONCLUSIONS

These results illustrate JNK enzymatic activity involvement during pulmonary fibrosis, and support systemic biomarker use for tracking disease progression and the potential clinical benefit of this novel intervention in IPF. Trial registration ClinicalTrials.gov NCT01203943.

Environmental, Inhaled and Ingested Causes of Pulmonary Fibrosis

Pulmonary fibrosis is a general term that refers to a collection of connective tissue around alveolar structures. There are over 200 disorders where the lungs may be involved in a fibrotic response. To determine the cause of pulmonary fibrosis requires an in depth understanding of the pathogenesis of pulmonary fibrosis and breadth of knowledge of the causative agents and associated disorders that may lead to pulmonary fibrosis. A comprehensive evaluation of the patient is absolutely essential, starting with detailed history that includes an occupational and environmental history because fibrogenic exposures can occur in many settings. Equally important is a history of ingestion of pharmaceutical or nonpharmaceutical substances. A physical examination and judicious investigations are always a part of any comprehensive clinical assessment but they are not commonly helpful in elucidating the cause of most pulmonary fibrotic disorders. Although, a chest film is invariably done, a logical and strongly recommended next step is a high-resolution computed tomography (HRCT). HRCT provides a better assessment of the radiological pattern, may suggest a diagnosis as well as direct the site, and type of lung biopsy. If the history and investigations do not lead to a diagnosis then a lung biopsy is required. Prevention or removal of the inciting agent is critical to the treatment of these disorders and in some instances corticosteroids may be of help.

Short beveled sharp cutting needle is superior to facet tip needle for ultrasound-guided rectus sheath block in children with umbilical hernia: a case series

BACKGROUND

The most common peripheral nerve blocks used in umbilical hernia repair are rectus sheath block and regional block (caudal block). Ultrasound guidance of peripheral nerve blocks has reduced the number of complications and improved the quality of blocks. The aim of this study is to assess the post rectus sheath block pain relief in pediatric patients coming for umbilical surgery, and to evaluate the easiness of soft tissue puncture and ultrasonic appearance of two different needle types.

METHODS

Twenty two (22) pediatric patients (age range: 1.5-8 years) scheduled for umbilical hernia repair were included in the study. Following the induction of general anesthesia, the ultrasonographic anatomy of the umbilical region was studied with a 5-16 MHz linear probe. An ultrasound-guided rectus sheath block in the lateral edge of both rectus abdominis muscles (RMs) was performed (total of 44 punctures). A 22 gauge short beveled sharp cutting needle 1.1 x 30 mm needle A (BD Insyte--W, Vialon material. Spain) was used in one side, and a Stimuplex A insulated Needle 22G 50mm (needle B) was used on the other side. Surgical conditions, intraoperative hemodynamic parameters, and postoperative analgesia were evaluated.

RESULTS

Ultrasonograghic visualization of the posterior sheath was possible in all patients. Needle A scored 72.7% of excellent needle tip and shaft view (16 out of 22) compared to 63.63% for needle B (14 out of 22). None of the needles scored poor view. The ultrasound guided rectus sheath blockade provided sufficient analgesia in all children with no need for additional analgesia except for one child who postoperatively requested morphine 0.1 mg/kg intravenously in recovery room. There were no complications.

CONCLUSIONS

Ultrasound guidance enables performances of an effective rectus sheath block for umbilical hernia in the lateral edge of the rectus muscle. Use of the sharp short beveled needle of 22 gauge intravenous (IV) cannula stylet provides easy, less traumatic skin and rectus muscle penetration and better needle visualization by the ultrasound.

Pulmonary rehabilitation improves long-term outcomes in interstitial lung disease: a prospective cohort study

BACKGROUND

Pulmonary rehabilitation improves outcomes in patients with interstitial lung disease (ILD), however it is unclear whether these effects are long lasting and which patients benefit most.

METHODS

Patients with ILD were recruited into this prospective cohort study from three pulmonary rehabilitation programs. Patients completed functional assessments (6-minute walk distance (6MWD), and 4-meter walk time) and surveys (quality of life, dyspnea, depression, and physical activity) before rehabilitation, after rehabilitation, and at six months. Changes from baseline were compared using a paired t-test. Independent predictors of change in 6MWD and quality of life were determined using multivariate analysis.

RESULTS

Fifty-four patients were recruited (22 with idiopathic pulmonary fibrosis), 50 patients (93%) completed the rehabilitation program, and 39 returned for six-month follow-up. 6MWD improved 57.6 m immediately after rehabilitation (95% confidence interval (CI) 40.2-75.1 m, p < 0.0005), and remained 49.8 m above baseline at six months (95%CI 15.0-84.6 m, p = 0.005). The majority of patients achieved the minimum clinically important difference for quality of life (51%), dyspnea (65%), and depression score (52%) immediately after rehabilitation, and improvements were still significant at 6-month follow-up for quality of life, depression, and physical activity. A low baseline 6MWD was the only independent predictor of improvement in 6MWD during rehabilitation (r = -0.49, p < 0.0005). Change in 6MWD was an independent predictor of change in quality of life (r = -0.36, p = 0.01).

CONCLUSIONS

Pulmonary rehabilitation improved multiple short- and long-term outcomes in patients with ILD. While all patients appear to benefit, ILD patients with a low baseline 6MWD had greater benefit from rehabilitation.

CLINICAL TRIALS REGISTRATION NUMBER

NCT01055730 (clinicaltrials.gov).

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.

Menopausal bone changes and incident fractures in diabetic women: a cohort study

SUMMARY

The purpose of this study was to evaluate the rate of bone loss and incident fractures in women with diabetes mellitus (DM) across menopause. During menopause, DM women experienced bone mineral density (BMD) loss that was faster at hip and slower at spine and had a higher risk of fractures, perhaps because of their earlier menopause. The increasing DM epidemic will contribute to higher fracture burden.

INTRODUCTION

Women with DM have a higher risk of fractures independent of age, body mass index (BMI), and BMD. Our objective is to evaluate if women with DM experience greater bone loss and more fractures across menopause.

METHODS

Two thousand one hundred seventy one women, aged 42 to 52 years at baseline (1996), enrolled in the Study of Women's Health Across the Nation (SWAN), a prospective study, with 8 years of annual follow up. One thousand three hundred forty six (62%) completed annual visit 7 (2004). Women with baseline fasting blood glucose level of ≥126 mg/dl and those being treated for diabetes were designated as DM. Annual assessment of menopausal stage, BMD, and urinary N-telopeptide (NTx) were carried out. Rate of change in BMD across menopause and annual self-report data for risk of incident fractures by DM status were determined.

RESULTS

Despite higher baseline BMD at hip (p = <0.001), and lumbar spine (p = <0.001), rate of decline in BMD was faster at hip (β = -0.45 vs. -0.11 gm/cm(2)/year, p = <0.001) for DM women, compared to non-DM. However, lumbar spine bone loss was slower in women with DM as compared to non-DM women (β = 0.04 vs. -0.25 gm/cm(2)/year, p = 0.004). DM women experienced menopause 3 years earlier than non-DM women (p = 0.002), and age adjusted incident fractures were two fold higher in women with DM compared to non-DM (RR = 2.20, 95% CI: 1.26-3.85, p = <0.006).

CONCLUSIONS

BMD loss is greater in hip and slower at spine in DM women during menopausal transition. Women with DM have a higher risk of fractures, perhaps because of their earlier menopause.

Pregnancy outcome in 396 pregnancies in patients with SLE in Saudi Arabia

The aim of this study was to examine the pregnancy outcomes in patients with systemic lupus erythematosus (SLE) and the effect of SLE flare and treatment on pregnancy outcomes. We performed a retrospective evaluation of all pregnancies occurring in patients with SLE during the 27-year period from 1980 to 2006. Of the 319 women with SLE planning pregnancy after SLE onset, 176 (55.2%) conceived resulting in 396 pregnancies. Live births were significantly lower in proportion (70.2% vs. 85.7%) and more likely to end in fetal deaths (29.7% vs. 14.2%) and preterm births (26.7% vs. 5.8 %) in pregnancies occurring after SLE onset than in pregnancies occurring before SLE onset (p < 0.0001). With respect to different disease manifestations, we found that fetal loss was significantly higher in patients with antiphospholipid (aPL) antibodies than without (p < 0.001). Preterm deliveries were significantly more frequent in patients with lupus nephritis, anti-Ro/SSA antibodies, hypertension, history of intravenous cyclophosphamide treatment and aPL than those without these features (p < 0.05). Neonates with intrauterine growth retardation (IUGR) neonates were more common in hypertensive and Raynaud's-positive pregnancies (p < 0.05). SLE flares occurred in 30.8% pregnancies. There was increased risk of fetal loss, preterm births and IUGR in pregnancies with SLE exacerbations than without (p < 0.05). Prednisolone was found to improve the rate of live births, although it was also a predictor of prematurity. The predictors of pregnancy loss were lupus nephritis (odds ratio (OR) 7.3), aPL (OR 3.9), and SLE flares in pregnancy (OR 1.9). There was higher risk of preterm deliveries in patients with lupus nephritis (OR 18.9), anti-Ro antibodies (OR 13.9), hypertension (OR 15.7) and SLE flares (OR 2.5). IUGR was found to be associated with hypertension (OR 37.7), Raynaud's (OR 12.3), and SLE flares (OR 4.2). In conclusion, pregnancies in SLE patients with active lupus nephritis, anti-Ro/SSA antibodies, aPL, hypertension, Raynaud's phenomenon, active disease at conception and SLE exacerbations are at a higher risk of adverse pregnancy outcomes. It is important to carefully plan pregnancy, and experienced rheumatologists and obstetricians should monitor SLE patients in pregnancy and postpartum.

Clinical and immunological manifestations in 624 SLE patients in Saudi Arabia

Our objective was to study the demographic, clinical, laboratory features, therapy, and outcome of systemic lupus erythematosus (SLE) patients. In this retrospective study, which covered a 27-year period (1980–2006), 624 SLE patients referring to King Khalid University hospital, Riyadh were included. There were 566 females and 58 males (9.8:1) with a mean age of 34.3 (range 8–71) years and mean age at disease onset of 25.3 years (range 0.08–67). The mean disease duration was 9.3 years (range 0.3–30). The most common disease manifestations were hematological abnormalities (82.7%), arthritis (80.4%), and mucocutaneous symptoms (64.3%). The prevalence of malar rash was 47.9%, discoid rash 17.6%, photosensitivity 30.6%, oral ulcers 39.1%, serositis 27.4%, nephritis 47.9%, and neuropsychiatric manifestations 27.6%. Lymphopenia (40.3%), anti-Ro (53.1%), anti-La (26.6%), anti-Sm (41.6%), anticardiolipin IgG (49.7%), and IgM (33.5%) antibodies were highly prevalent. Antinuclear antibodies were detected in 99.7% and anti-DNA in 80.1% patients. Low C3 and C4 were observed in 45.4% and 42.2%, respectively. Therapy included oral steroids (96.2%), IV cyclophosphamide (34.1%) and azathioprine (32.1%) along with other drugs. Long-term remission was achieved in 82.4%, disease was active in 2.6%, renal failure occurred in 4.3% requiring dialysis, 6.7% lost follow up and 4.0% patients died. Infections (48%) and active SLE (36%) were the common causes of death. The 5- and 10-year patient survival rate was 98% and 97%, respectively. This study suggests that, in our patients, SLE manifests with features similar to SLE patients from other Arab countries and Caucasia. In comparison to Caucasians, higher prevalence of anti-Ro antibodies is observed in our study, in some Middle-Eastern and Asian countries; this may likely be due to inter-ethnic variation owing to genetic differences. Our 5-year patient survival rate was similar to that of western countries, while 10-year survival rate was better than that of most places.

The role of TGF-beta in pulmonary fibrosis

Pulmonary fibrosis is an irreversible accumulation of connective tissue in the interstitium of the lung. The pathogenesis of pulmonary fibrosis is not well understood. Research on animal models and studies of human lung disease suggest the initiating events may be a combination of pulmonary injury and the recruitment of inflammatory cells, mainly macrophages. A number of well characterized cytokines, including TGF-beta, have been either found in the injured lung or produced by inflammatory cells removed from the lung. In an animal model of pulmonary fibrosis, TGF-beta production is increased prior to collagen synthesis and is mainly produced by alveolar macrophages. In advanced idiopathic pulmonary fibrosis, a human fibrotic lung disease, extensive TGF-beta deposition can be detected by immunohistochemical staining, primarily in epithelial cells in areas of lung regeneration and remodelling. This suggests that the pathogenesis of the progressive fibrosis characteristic of this lung disease may be an aberrant repair process.

TGF-beta1 increases proliferation of airway smooth muscle cells by phosphorylation of map kinases

BACKGROUND

Airway remodeling in asthma is the result of increased expression of connective tissue proteins, airway smooth muscle cell (ASMC) hyperplasia and hypertrophy. TGF-beta1 has been found to increase ASMC proliferation. The activation of mitogen-activated protein kinases (MAPKs), p38, ERK, and JNK, is critical to the signal transduction associated with cell proliferation. In the present study, we determined the role of phosphorylated MAPKs in TGF-beta1 induced ASMC proliferation.

METHODS

Confluent and growth-arrested bovine ASMCs were treated with TGF-beta1. Proliferation was measured by [3H]-thymidine incorporation and cell counting. Expressions of phosphorylated p38, ERK1/2, and JNK were determined by Western analysis.

RESULTS

In a concentration-dependent manner, TGF-beta1 increased [3H]-thymidine incorporation and cell number of ASMCs. TGF-beta1 also enhanced serum-induced ASMC proliferation. Although ASMCs cultured with TGF-beta1 had a significant increase in phosphorylated p38, ERK1/2, and JNK, the maximal phosphorylation of each MAPK had a varied onset after incubation with TGF-beta1. TGF-beta1 induced DNA synthesis was inhibited by SB 203580 or PD 98059, selective inhibitors of p38 and MAP kinase kinase (MEK), respectively. Antibodies against EGF, FGF-2, IGF-I, and PDGF did not inhibit the TGF-beta1 induced DNA synthesis.

CONCLUSION

Our data indicate that ASMCs proliferate in response to TGF-beta1, which is mediated by phosphorylation of p38 and ERK1/2. These findings suggest that TGF-beta1 which is expressed in airways of asthmatics may contribute to irreversible airway remodeling by enhancing ASMC proliferation.

Proliferation of Pulmonary Interstitial Fibroblasts Is Mediated by Transforming Growth Factor-β1-induced Release of Extracellular Fibroblast Growth Factor-2 and Phosphorylation of p38 MAPK and JNK

Idiopathic pulmonary fibrosis (IPF; a progressive lung disease) is characterized by parenchymal remodeling with enlarged air spaces called honeycomb cysts and palisades of fibroblasts called fibroblast foci. In IPF, lung epithelial cells covering honeycomb cysts and fibroblast foci aberrantly express the active conformation of the potent fibrogenic cytokine transforming growth factor-beta1 (TGF-beta1). Using explanted rat lung slices, we transfected alveolar epithelial cells with the retrovirus pMX containing a site-directed mutation in which Cys223 and Cys225 were substituted with serines, resulting in release of biologically active TGF-beta1 and fibroblast proliferation and remodeling that resembled IPF. Fibroblasts obtained from transfected explants and in culture for 6 weeks incorporated 6.59 +/- 1.55-fold more [3H]thymidine compared with control fibroblasts without transfection or fibroblasts obtained from transfected explants cultured with antibody to fibroblast growth factor-2 (FGF-2). Primary lung fibroblasts obtained from normal rat lungs cultured with TGF-beta1 expressed increased levels of phosphorylated p38 MAPK and JNK, but not ERK1/2. The presence of TGF-beta1 caused an immediate release of extracellular FGF-2 from primary pulmonary fibroblasts; and in the presence of anti-FGF-2 antibody, phosphorylated p38 MAPK and JNK were abrogated. TGF-beta inhibits cell proliferation by suppression of c-Myc and induction of p15INK46, p21CIP1, or p27KIP. Fibroblasts cultured with TGF-beta1 showed no regulation of c-Myc or induction of p15INK46, p21CIP1,or p27KIP. These findings suggest that pulmonary fibroblasts may not respond to the anti-proliferative effects of TGF-beta1, but proliferate in response to TGF-beta1 indirectly by the release of FGF-2, which induces phosphorylation of p38 MAPK and JNK.

Angiotensin II type 1 receptor blocker inhibits pulmonary injury

PURPOSE

Pulmonary damage and fibrosis may be the result of diverse forms of injury and there is an association between pulmonary diseases and cardiovascular events. The purpose of this study was to evaluate the effects of an angiotensin II type 1 receptor blocker, valsartan, on systemic, cellular, and fibrotic consequences of pulmonary injury induced by the anti-neoplastic antibiotic, bleomycin.

METHODS

Sprague Dawly rats were used in the classical bleomycin model of pulmonary fibrosis. Bleomycin (1 unit, n = 7) was administered intra-tracheally to induce lung injury. Valsartan (0.66 mg) was given either concomitantly (n = 9) or for two days prior to bleomycin (n = 8). A control group (n = 6) was given normal saline.

RESULTS

Valsartan-treated animals showed abrogation of weight loss, suppression of release of total and active transforming growth factor beta-1 (TGF-beta1), and diminished connective tissue synthesis. In an explant, lung tissue culture model devoid of alveolar macrophages (saline control, n = 3; bleomycin, n = 6; bleomycin plus valsartan, n = 12), both total and active TGF-beta1 were suppressed in the valsartan-treated cohort.

CONCLUSIONS

Valsartan, known to have cardio-protective properties, was shown to be protective of bleomycin-induced pulmonary injury. Thus, ARBs may be beneficial in both cardiac and pulmonary diseases.

Idiopathic pulmonary fibrosis: current understanding of the pathogenesis and the status of treatment

Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal pulmonary fibrotic lung disease. The diagnostic histological changes are called usual interstitial pneumonia and are characterized by histological temporal heterogeneity, whereby normal lung tissue is interspersed with interstitial fibrosis, honeycomb cysts and fibroblast foci. Pulmonary functions show restricted volumes and capacities, preserved flows and evidence of decreased gas exchange. High-resolution computed axial tomography demonstrates evidence of fibrosis and lung remodelling such as honeycomb cysts and traction bronchiectasis. There is no known effective treatment for IPF, but lung transplantation improves survival.

Release of biologically active TGF-beta1 by alveolar epithelial cells results in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal fibrotic lung disease. Transforming growth factor (TGF)-beta1 is present in a biologically active conformation in the epithelial cells lining lesions with advanced IPF. To determine the role of aberrant expression of biologically active TGF-beta1 by alveolar epithelial cells (AECs), the AECs of explanted normal rat lungs were transfected with the TGF-beta1 gene using the retrovirus pMX-L-s223,225-TGF-beta1. In situ hybridization using a digoxigenin-labeled cDNA of the puromycin resistance gene contained in the pMX demonstrated that pMX-L-s233,225-TGF-beta1 was selectively transfected into AECs of the explants. Conditioned media overlying explants obtained 7 days after being treated with pMX-L-s223,225-TGF-beta1 contained 14.5 +/- 3.15 pg/ml of active TGF-beta1. With the use of Masson's trichrome staining of explant sections obtained 14 days after transfection, there were lesions similar to those in IPF, characterized by type II AEC hyperplasia, interstitial thickening, extensive increase in interstitial and subepithelial collagen, an increase in the number of fibroblasts, and areas resembling fibroblast buds. Collagens I, III, IV, and V and fibronectin were increased in explants treated with pMX-L-s223,225-TGF-beta1. The findings in the current study suggest that IPF may be a disorder of epithelial cells and not inflammatory cells.

GM-CSF increases airway smooth muscle cell connective tissue expression by inducing TGF-beta receptors

Fibrosis around the smooth muscle of asthmatic airway walls leads to irreversible airway obstruction. Bronchial epithelial cells release granulocyte/macrophage colony-stimulating factor (GM-CSF) in asthmatics and are in close proximity to airway smooth muscle cells (ASMC). The findings in this study demonstrate that GM-CSF induces confluent, prolonged, serum-deprived cultures of ASMC to increase expression of collagen I and fibronectin. GM-CSF also induced ASMC to increase the expression of transforming growth factor (TGF)-beta receptors type I, II, and III (TbetaR-I, TbetaR-II, TbetaR-III), but had no detectable effect on the release of TGF-beta1 by the same ASMC. The presence of GM-CSF also induced the association of TGF-beta1 with TbetaR-III, which enhances binding of TGF-beta1 to TbetaR-II. The induction of TbetaRs was parallel to the increased induction of phosphorylated Smad2 (pSmad2) and connective tissue growth factor (CTGF), indicative of TGF-beta-mediated connective tissue synthesis. Dexamethasone decreased GM-CSF-induced TbetaR-I, TbetaR-II, TbetaR-III, pSmad2, CTGF, collagen I, and fibronectin. In conclusion, GM-CSF increases the responsiveness of ASMC to TGF-beta1-mediated connective tissue expression by induction of TbetaRs, which is inhibited by corticosteroids.

In vitro wounding of airway smooth muscle cell monolayers increases expression of TGF-beta receptors

During an exacerbation of asthma, there is bronchial epithelial cell injury and influx of inflammatory cells. In these instances, the release of proteases and various cytokines could lead to injury of the airway smooth muscle cells (ASMCs). Airway remodeling is a characteristic finding in asthma but the role of ASMC injury in remodeling is unknown. Previously, we demonstrated that mechanical wounding of confluent monolayers of bovine ASMCs resulted in the release of biologically active transforming growth factor-beta1 (TGF-beta1), which in turn, induced collagen I expression. In the present study, we demonstrate that after mechanical wounding, ASMCs had an increased expression of the signal transducing TGF-beta receptors TbetaR-I and TbetaR-II as detected by flow cytometry and Western analysis. Corticosteroids are standard therapy in asthma and the presence of dexamethasone decreased wound-induced release of TGF-beta1 and the expression of collagen I, fibronectin, and TbetaR-II. These results suggest that ASMC injury may play an important role in airway fibrosis mediated by TGF-beta1, which can be prevented by the use of corticosteroids.

Characterization of the Oum Er Rbia (Morocco) high basin karstic water sources by using solid state nuclear track detectors and radon as a natural tracer

Uranium and thorium contents as well as radon alpha-activities per unit volume were evaluated inside different water samples by using a method based on calculating the CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs) detection efficiencies for the emitted alpha-particles and measuring the resulting track density rates. The validity of the SSNTD technique utilized was checked by analysing uranyl nitrate (UO2(NO3)26H2O) standard solutions. A relationship between water radon concentration and water transmission of different water sources belonging to two regions of the Middle Atlas (Morocco) water reservoir was found. The influence of the water flow rate as well as the permeability and fracture system of the host rocks of the sources studied was investigated.

Increase in the beta chain of hepatocyte growth factor (HGF beta) precedes c-met expression after bleomycin-induced lung injury in the rat

After lung injury the regeneration of the alveolar epithelium is highly dependent on the proliferation of type II alveolar epithelial cells (AECs). Hepatocyte growth factor (HGF), a potent epithelial cell mitogen, is present as a single chain in normal tissue, but after injury HGF is converted to an active form composed of an alpha and a beta chain. In this study it was demonstrated that there was an increase in the beta chain of HGF 4 days after bleomycin administration, coinciding with the time of maximal type II AEC proliferation. Bronchoalveolar lavage fluid (BALF) obtained 4 days after bleomycin administration was maximally mitogenic to L2 cells, a nontransformed rat alveolar epithelial cell line. Type II cells isolated from normal rats do not express the HGF receptor, c-met. However, 4 days after bleomycin injury, using Western blot analysis, an increase in c-met was detected in AEC protein extracts. HGF induced c-met expression by L2 cells and neutralizing antibodies to HGF inhibited the mitogenic activity in the BALF. These findings suggest that HGF may regulate its own receptor on AECs and is an important mitogen for AECs 4 days after bleomycin administration.

Differential expression of transforming growth factor-beta type I and II receptors by pulmonary cells in bleomycin-induced lung injury: correlation with repair and fibrosis

In a rat model of lung injury induced by the antineoplastic antibiotic, bleomycin, there is loss of type I alveolar epithelial cells (AECs) followed by infiltration of activated inflammatory cells, type II AEC proliferation, and fibrosis. At 4 and 7 days after bleomycin administration alveolar macrophages have increased production and release of active transforming growth factor (TGF)-beta1, an inhibitor of epithelial cell proliferation. Paradoxically at these same time intervals there is a concomitant induction of type II AEC proliferation. For TGF-beta-mediated signal transduction to occur, the expression of both TCF-beta receptor types I (TbetaR-I) and II (TbetaR-II) must be present. Using immunohistochemistry and in situ hybridization, 4 and 7 days after bleomycin administration the expression of TbetaR-I on AECs was reduced whereas that of TbetaR-II was unaltered. However, 14 and 28 days after bleomycin injury, when there is decreased proliferation and induction of differentiation of type II AECs, there was a return of TbetaR-I expression on AECs. In contrast, TbetaR-I and TbetaR-II were observed on interstitial fibroblasts at all time intervals after bleomycin administration. Because both TbetaR-I and TbetaR-II are required for signal transduction, the reduction of TbetaR-I levels on the alveolar epithelium may alter the sensitivity of AECs to the antiproliferative effects of TGF-beta1 present in increased quantities following bleomycin injury. The loss of an antiproliferative response to TGF-beta1 may be important for the regeneration of the alveolar epithelium by proliferation while the expression of both receptors onfibroblasts would result in TGF-1 signaling for the synthesis of connective tissue proteins. Ourfindings suggest that during bleomycin-induced pulmonary fibrosis, the effects of TGF-beta1 on cells may be regulated by the expression of TbetaRs.

Regulation of the effects of TGF-beta 1 by activation of latent TGF-beta 1 and differential expression of TGF-beta receptors (T beta R-I and T beta R-II) in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is characterised by subpleural fibrosis that progresses to involve all areas of the lung. The expression of transforming growth factor-beta1 (TGF-beta 1), a potent regulator of connective tissue synthesis, is increased in lung sections of patients with IPF. TGF-beta 1 is generally released in a biologically latent form (L-TGF-beta 1). Before being biologically active, TGF-beta must be converted to its active form and interact with both TGF-beta receptors type I and II (T beta R-I and T beta R-II). TGF-beta latency binding protein 1 (LTBP-1), which facilitates the release and activation of L-TGF-beta 1, is also important in the biology of TGF-beta 1.

METHODS

Open lung biopsy samples from patients with IPF and normal controls were examined to localise T beta R-I, T beta R-II, and LTBP-1. Alveolar macrophages (AM) and bronchoalveolar lavage (BAL) fluid were examined using the CCL-64 bioassay to determine if TGF-beta is present in its active form in the lungs of patients with IPF.

RESULTS

Immunoreactive L-TGF-beta 1 was present in all lung cells of patients with IPF except for fibroblasts in the subepithelial regions of honeycomb cysts. LTBP-1 was detected primarily in AM and epithelial cells lining honeycomb cysts in areas of advanced IPF. In normal lungs LTBP-1 immunoreactivity was observed in a few AM. AM from the upper and lower lobes of patients with IPF secreted 1.6 (0.6) fmol and 4.1 (1.9) fmol active TGF-beta, respectively, while AM from the lower lobes of control patients secreted no active TGF-beta (p< or =0.01 for TGF-beta in the conditioned media from AM obtained from the lower lobes of IPF patients v normal controls). The difference in percentage active TGF-beta secreted by AM from the lower lobes of patients with IPF and the lower lobes of control patients was significant (p< or =0.01), but the difference between the total TGF-beta secreted from these lobes was not significant. The difference in active TGF-beta in conditioned media of AM from the upper and lower lobes of patients with IPF was also not statistically significant. BAL fluid from the upper and lower lobes of patients with IPF contained 0.7 (0.2) fmol and 2.9 (1.2) fmol active TGF-beta, respectively (p< or =0.03). The percentage of active TGF-beta in the upper and lower lobes was 17.6 (1.0)% and 78.4 (1.6)%, respectively (p< or =0.03). In contrast, BAL fluid from control patients contained small amounts of L-TGF-beta. Using immunostaining, both T beta R-I and T beta R-II were present on all cells of normal lungs but T beta R-I was markedly reduced in most cells in areas of honeycomb cysts except for interstitial myofibroblasts in lungs of patients with IPF. TGF-beta 1 inhibits epithelial cell proliferation and a lack of T beta R-I expression by epithelial cells lining honeycomb cysts would facilitate repair of the alveoli by epithelial cell proliferation. However, the presence of both T beta Rs on fibroblasts is likely to result in a response to TGF-beta 1 for synthesis of connective tissue proteins. Our findings show that biologically active TGF-beta 1 is only present in the lungs of patients with IPF. In addition, the effects of TGF-beta 1 on cells may be further regulated by the expression of T beta Rs.

CONCLUSION

Activation of L-TGF-beta 1 and the differential expression of T beta Rs may be important in the pathogenesis of remodelling and fibrosis in IPF.

Release of biologically active TGF-beta from airway smooth muscle cells induces autocrine synthesis of collagen

In severe or chronic asthma, there is an increase in airway smooth muscle cell (ASMC) mass as well as an increase in connective tissue proteins in the smooth muscle layer of airways. Transforming growth factor-beta (TGF-beta) exists in three isoforms in mammals and is a potent regulator of connective tissue protein synthesis. Using immunohistochemistry, we had previously demonstrated that ASMCs contain large quantities of TGF-beta1-3. In this study, we demonstrate that bovine ASMC-derived TGF-beta associates with the TGF-beta latency binding protein-1 (LTBP-1) expressed by the same cells. The TGF-beta associated with LTBP-1 localizes TGF-beta extracellularly. Furthermore, plasmin, a serine protease, regulates the secretion of a biologically active form of TGF-beta by ASMCs as well as the release of extracellular TGF-beta. The biologically active TGF-beta released by plasmin induces ASMCs to synthesize collagen I in an autocrine manner. The autocrine induction of collagen expression by ASMCs may contribute to the irreversible fibrosis and remodeling seen in the airways of some asthmatics.

Post translational activation of latent transforming growth factor beta (L-TGF-beta): clinical implications

Transforming growth factor-betas (TGF-betas) are multifunctional cytokines that exist in 3 isoforms in mammals. The TGF-betas are ubiquitously expressed and all isoforms are secreted as biologically inactive precursors called latent TGF-beta (L-TGF-beta). L-TGF-betas are generally not effective molecules because they are unable to interact with their receptors. However, the removal of or conformational change of the precursor protein called the latency associated peptide (LAP) results in the generation of biologically active TGF-beta. In vitro active TGF-beta has many biological effects but from a clinical point of view one of the most recognized associations of aberrant TGF-beta production is with diseases characterized by enhanced connective tissue synthesis. Recently a number of observations in the context of fibrotic disorders suggest mechanisms of activation of L-TGF-beta1 in vivo. The recognition of mechanisms that activate L-TGF-beta1 in vivo offers the possibility of interfering with the activation of L-TGF-beta1 for therapeutic purposes.

A role for hyaluronan in macrophage accumulation and collagen deposition after bleomycin-induced lung injury

Elevated concentrations of hyaluronan (HA) are associated with the accumulation of macrophages in the lung after injury. We have investigated the role of HA in the inflammatory and fibrotic responses to lung injury using the intratracheal instillation of bleomycin in rats as a model. After bleomycin-induced lung injury, both HA content in bronchoalveolar lavage (BAL) and staining for HA in macrophages accumulating in injured areas of the lung were maximal at 4 d. Increased HA in BAL correlated with increased locomotion of isolated alveolar macrophages. HA-binding peptide was able to specifically block macrophage motility in vitro. Importantly, systemic administration of HA-binding peptide to rats before injury not only decreased alveolar macrophage motility and accumulation in the lung, but also reduced lung collagen alpha (I) messenger RNA and hydroxyproline contents. We propose a model in which HA plays a critical role in the inflammatory response and fibrotic consequences of acute lung injury.

A CD36 synthetic peptide inhibits bleomycin-induced pulmonary inflammation and connective tissue synthesis in the rat

Transforming growth factor (TGF)-beta1 is an important regulator of inflammation and fibrosis. TGF-beta1 is usually secreted as a biologically latent protein called latent TGF-beta1 (L-TGF-beta1). L-TGF-beta1 has no biologic effect unless L-TGF-beta1 is converted to its active form. Using a well-recognized model of lung injury induced by the antineoplastic antibiotic bleomycin (Blm), we demonstrated that 7 d after intratracheal Blm administration, total lung TGF-beta was maximally increased. This induction was due to TGF-beta1 production by alveolar macrophages that, when explanted, generated increased quantities of L-TGF-beta1 complexed with the glycoprotein thrombospondin (TSP)-1. The TSP-1/L-TGF-beta1 complex was associated with CD36, a receptor for TSP-1. The association of TSP-1/L-TGF-beta1 to CD36 was critical for plasmin-mediated release of mature TGF-beta1. In this paper we show that, compared with administration of Blm by itself, when a synthetic peptide of CD36 between amino acids 93 and 110 is given concomitantly with Blm to rats, alveolar macrophages generate markedly less active TGF-beta1, the rats gain weight more rapidly, and there is less inflammation, collagen I and III, and fibronectin synthesis. These findings demonstrate a novel in vivo mechanism of activation of L-TGF-beta1 in lung injury and the importance of alveolar macrophage- derived active TGF-beta1 in the pathogenesis of pulmonary inflammation and fibrosis.

Evidence for the involvement of dietary lipids on the modulation of transforming growth factor-beta1 in the platelets of male rats

Transforming growth factor beta1 (TGF-beta1), a multifunctional cytokine participates in the proliferation and differentiation of various cell types. Platelets are an important source of TGF-beta1 and are physiologically linked to a variety of chronic illnesses including cancer, heart disease and inflammation. It is well known that dietary lipids modulate platelet function. Whether dietary lipids affect growth factor status of platelets is not known. This study addresses the effect of dietary lipids on TGF-beta1 status of the platelets. Male 8 month-old Sprague Dawley rats were allocated to different diet groups. The high fat diets ( 18% by weight) comprising of high fat beef tallow (HFB), high fat corn oil (HFC), high fat fish oil (HFF) and high fat olive oil (HFO) and one low fat diet containing low fat soybean oil (LFS) (5% by weight) were fed to the experimental animals for 6 weeks. The TGF-beta1 status in the platelet lysate was assessed by using the CCL-64 mink lung cell bioassay and by Western blot analysis. Platelet lysates were evaluated for their ability to inhibit the growth of the CCL-64 mink lung cells, unexpectedly platelet lysates stimulated growth. The stimulatory effect of platelet lysate was in the order HFF > HFO > HFB > HFC > LFS. Acidification of the lysates to activate the latent form of TGF-beta1 resulted in the loss of the growth stimulatory potential of the platelet lysates in all the groups. Western blot analysis of the platelet lysates to detect the level of TGF-beta1 protein demonstrated that HFB diet group had the highest level of TGF-beta1 and the HFC diet group had the lowest level of TGF-beta1 and were significantly different (p < 0.05) as compared to the other three diet groups. These findings demonstrate that dietary lipids varying in their fatty acid composition, profoundly affect the level of growth modulating constituents of the platelets. Further studies are warranted to refine our understanding of the effect of dietary constituents on the physiology of the platelets.

Massive upper GI bleeding in a child

Two year and seven month female child, known case of cerebral palsy, presented with sudden onset of hematemesis, which progressed to uncontrollable massive upper GI bleeding requiering devascularization and more than 36 blood transfusions.

TGF-beta: from latent to active

The transforming growth factor-betas (TGF-betas) are synthesized as precursor proteins that are modified intracellularly prior to secretion. One of the most relevant intracellular modifications is the cleavage of the C-terminal pro-region from the N-terminal portion of the protein. The C-terminal pro-region is referred to as the latency-associated peptide (LAP) while the N-terminal region is called the mature TGF-beta or active TGF-beta. However, with some exceptions the LAP noncovalently associates with the mature TGF-beta prior to secretion. When the mature TGF-beta is associated with the LAP it is called L-TGF-beta and cannot interact with its receptor and has no biological effect. The TGF-betas and their receptors are very ubiquitously expressed, suggesting that the regulation of TGF-beta activity is likely to be complex and multifactorial. However, one of the most important means of controlling the biological effects of TGF-beta is the regulation of converting L-TGF-beta to active TGF-beta. The current literature supports two major mechanisms of activation of L-TGF-beta and suggests that the mechanism of activation of L-TGF-beta may be varied and context-dependent. For TGF-beta to become biologically active the LAP has to be either released from its associations with L-TGF-beta or undergo conformational change such that the LAP is not released from the L-TGF-beta complex but exposes the TGF-beta receptor binding site. Since TGF-beta has been associated with the pathogenesis of numerous diseases, the various mechanisms of activation of L-TGF-beta in context offer the possibility of controlling TGF-beta activity localized to the organ of involvement and to a more specific disease process.

Activation of rat alveolar macrophage-derived latent transforming growth factor beta-1 by plasmin requires interaction with thrombospondin-1 and its cell surface receptor, CD36

Transforming growth factor-beta-1 (TGF-beta1) is secreted by cells in a latent form (L-TGF-beta1) noncovalently bound to a latency-associated peptide. Activated alveolar macrophages obtained from rat lungs after bleomycin-induced pulmonary injury released increased amounts of active TGF-beta1 as well as plasmin, a protease, and thrombospondin-1 (TSP-1), a trimeric glycoprotein. Previously we had demonstrated that plasmin was critical to the activation of L-TGF- beta1. In the present study we demonstrated that TSP-1 is also important for the activation of L-TGF- beta1 because the activation can be inhibited by anti-TSP-1 monoclonal antibody. Proteins obtained from alveolar macrophage cell lysates immunoprecipitated with antibodies specific for TSP-1 were identified on immunoblots as LAP and TGF-beta1, indicating that TSP-1/L-TGF-beta1 complexes are present on alveolar macrophages. However, in the presence of plasmin both latency-associated peptide and TGF-beta1 were decreased in the same cell lysates, indicating that L-TGF-beta1 associated with TSP-1 is released by plasmin. Using immunofluorescence and antibodies to TGF-beta1 and CD36, a receptor for TSP-1, there was colocalization of TGF-beta1 with CD36. Because TSP-1 but not TGF-beta1 is a natural ligand for CD36, these findings suggest that the L-TGF-beta1 in a complex with TSP-1 localizes to the macrophage cell surface when TSP-1 interacts with its receptor, CD36. Furthermore, the association of TSP-1/L-TGF-beta1 complex with CD36 is necessary to the activation of L-TGF-beta1 because antibodies to CD36 prevent the colocalization of TGF-beta1 with CD36 as observed by immunofluorescence and inhibit activation of the L-TGF-beta1 by explanted alveolar macrophages. These findings suggest that activation of L-TGF-beta1 by plasmin occurs at the cell surface of activated alveolar macrophages and requires a TSP-1/CD36 interaction.

Use of mouth pressure twitches induced by cervical magnetic stimulation to assess voluntary activation of the diaphragm

There is a need for a simple method to assess the adequacy of diaphragm activation during voluntary inspiratory efforts in patients with suspected respiratory muscle weakness. We have compared mouth (Pmo,t), oesophageal (Poes,t) and transdiaphragmatic (Pdi,t) twitch pressure elicited by cervical magnetic stimulation (CMS) in five normal men (mean (SD) age 32.2 (1.8) yrs) on two separate study days. Single magnetic stimuli were delivered at functional residual capacity during relaxation and during graded voluntary inspiratory efforts against a closed airway. As voluntary-effort transdiaphragmatic and oesophageal pressure increased, Pdi,t and Poes,t decreased linearly (r range, respectively, 0.82-0.98 and 0.87-0.95). During relaxation, Pmo,t was unreliable due to the poor transmission of intrathoracic pressure, but during inspiratory efforts, the relation between voluntary mouth pressure and Pmo,t was also linear (r range 0.84-0.95). On average, our subjects voluntarily generated 99, 100 and 102% of the maximum transdiaphragmatic, oesophageal and mouth pressures predicted by the respective linear regression equations. Pmo,t was correlated to both Poes,t and Pdi,t during inspiratory efforts, but not during relaxation. These studies confirm that twitch pressures induced by CMS during inspiratory efforts can be assessed at the mouth in normal subjects, providing a simple and non-invasive technique for assessing diaphragm activation during voluntary inspiratory efforts. Potentially, this technique could be made more sensitive and accurate and applied to detect submaximal efforts in patients.