Budesonide/formoterol effects on metalloproteolytic balance in TGFbeta-activated human lung fibroblasts

Comprehensive review of potential drugs with anti-pulmonary fibrosis properties

Pulmonary fibrosis is a chronic and progressive lung disease characterized by the accumulation of scar tissue in the lungs, which leads to impaired lung function and reduced quality of life. The prognosis for idiopathic pulmonary fibrosis (IPF), which is the most common form of pulmonary fibrosis, is generally poor. The median survival for patients with IPF is estimated to be around 3-5 years from the time of diagnosis. Currently, there are two approved drugs (Pirfenidone and Nintedanib) for the treatment of IPF. However, Pirfenidone and Nintedanib are not able to reverse or cure pulmonary fibrosis. There is a need for new pharmacological interventions that can slow or halt disease progression and cure pulmonary fibrosis. This review aims to provide an updated overview of current and future drug interventions for idiopathic pulmonary fibrosis, and to summarize possible targets of potential anti-pulmonary fibrosis drugs, providing theoretical support for further clinical combination therapy or the development of new drugs.

TIMP-1 and its potential diagnostic and prognostic value in pulmonary diseases

Tissue inhibitors of metalloproteases (TIMPs) have caught the attention of many scientists due to their role in various physiological and pathological processes. TIMP-1, 2, 3, and 4 are known members of the TIMPs family. TIMPs exert their biological effects by, but are not limited to, inhibiting the activity of metalloproteases (MMPs). The balance between MMPs and TIMPs is critical for maintaining homeostasis of the extracellular matrix (ECM), while the imbalance between MMPs and TIMPs can lead to pathological changes, such as cancer. In this review, we summarized the current knowledge of TIMP-1 in several pulmonary diseases namely, acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), pneumonia, asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis, and pulmonary fibrosis. Considering the potential of TIMP-1 serving as a non-invasive diagnostic and/or prognostic biomarker, we also reviewed the circulating TIMP-1 levels in translational and clinical studies.

Therapeutic targets in lung tissue remodelling and fibrosis

Structural changes involving tissue remodelling and fibrosis are major features of many pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Abnormal deposition of extracellular matrix (ECM) proteins is a key factor in the development of tissue remodelling that results in symptoms and impaired lung function in these diseases. Tissue remodelling in the lungs is complex and differs between compartments. Some pathways are common but tissue remodelling around the airways and in the parenchyma have different morphologies. Hence it is critical to evaluate both common fibrotic pathways and those that are specific to different compartments; thereby expanding the understanding of the pathogenesis of fibrosis and remodelling in the airways and parenchyma in asthma, COPD and IPF with a view to developing therapeutic strategies for each. Here we review the current understanding of remodelling features and underlying mechanisms in these major respiratory diseases. The differences and similarities of remodelling are used to highlight potential common therapeutic targets and strategies. One central pathway in remodelling processes involves transforming growth factor (TGF)-β induced fibroblast activation and myofibroblast differentiation that increases ECM production. The current treatments and clinical trials targeting remodelling are described, as well as potential future directions. These endeavours are indicative of the renewed effort and optimism for drug discovery targeting tissue remodelling and fibrosis.

Blocking LOXL2 and TGFβ1 signalling induces collagen I turnover in precision-cut lung slices derived from patients with idiopathic pulmonary fibrosis

We recently identified epigallocatechin gallate (EGCG), a trihydroxyphenolic compound, as a dual inhibitor of lysyl oxidase-like2 and transforming growth factor-β1 (TGFβ1) receptor kinase that when given orally to patients with idiopathic pulmonary fibrosis (IPF) reversed profibrotic biomarkers in their diagnostic biopsies. Here, we extend these findings to advanced pulmonary fibrosis using cultured precision-cut lung slices from explants of patients with IPF undergoing transplantation. During these experiments, we were surprised to discover that not only did EGCG attenuate TGFβ1 signalling and new collagen accumulation but also activated matrix metalloproteinase-dependent collagen I turnover, raising the possibility of slow fibrosis resolution with continued treatment.

Bidirectional interaction of airway epithelial remodeling and inflammation in asthma

Asthma is a chronic disease of the airways that has long been viewed predominately as an inflammatory condition. Accordingly, current therapeutic interventions focus primarily on resolving inflammation. However, the mainstay of asthma therapy neither fully improves lung function nor prevents disease exacerbations, suggesting involvement of other factors. An emerging concept now holds that airway remodeling, another major pathological feature of asthma, is as important as inflammation in asthma pathogenesis. Structural changes associated with asthma include disrupted epithelial integrity, subepithelial fibrosis, goblet cell hyperplasia/metaplasia, smooth muscle hypertrophy/hyperplasia, and enhanced vascularity. These alterations are hypothesized to contribute to airway hyperresponsiveness, airway obstruction, airflow limitation, and progressive decline of lung function in asthmatic individuals. Consequently, targeting inflammation alone does not suffice to provide optimal clinical benefits. Here we review asthmatic airway remodeling, focusing on airway epithelium, which is critical to maintaining a healthy respiratory system, and is the primary defense against inhaled irritants. In asthma, airway epithelium is both a mediator and target of inflammation, manifesting remodeling and resulting obstruction among its downstream effects. We also highlight the potential benefits of therapeutically targeting airway structural alterations. Since pathological tissue remodeling is likewise observed in other injury- and inflammation-prone tissues and organs, our discussion may have implications beyond asthma and lung disease.

Metalloproteinases and their Inhibitors under the Course of Immunostimulation by CPG-ODN and Specific Antigen Inhalation in Equine Asthma

Objectives

Inhalation of immunostimulatory bacterial DNA segments (cytosine-phosphate-guanosine-oligodeoxynucleotides, CpG-ODN) normalizes clinical and cytologic parameters in severe equine asthma. We hypothesized that CpG-ODN inhalation also reduces the misbalance of elastinolytic activity in asthmatic horses.

Methods

Twenty asthmatic horses diagnosed by clinical examinations using a scoring system were included. All horses inhaled CpG-ODNs for 14 days in 2-day intervals. Matrix metalloproteinase (MMP-2/-9) and tissue inhibitors of metalloproteinase (TIMP-1/-2) concentrations were measured in tracheal aspirates using equine sandwich ELISAs before and 2 and 6 weeks after CpG-ODN inhalation.

Results

MMP and TIMP concentrations correlated with the results of clinical scoring in all stages of equine asthma. Inhalation therapy led to significant reductions in clinical scores. MMP-2, MMP-9, and TIMP-2 concentrations were significantly reduced immediately, and all MMP and TIMP concentrations 6 weeks after therapy.

Discussion

In equine asthma, overexpression of MMPs contributes to pathological tissue destruction, while TIMPs counteract MMPs with overexpression leading to fibrosis formation. The results of this study show that CpG-ODN inhalation may be an effective therapy to address a misbalance in equine asthma.

Conclusions

Misbalance of elastinolytic activity seems to improve by CpG-ODN inhalation for at least 6 weeks posttherapy, which may reduce the remodeling of the extracellular matrix. Further studies should evaluate this effect in comparison to glucocorticoid inhalation therapy.

Significance

CpG-ODN inhalation may be an effective therapy in the prevention of pulmonary fibrosis formation in equine asthma.

11Beta-hydroxysteroid dehydrogenase-1 deficiency or inhibition enhances hepatic myofibroblast activation in murine liver fibrosis

A hallmark of chronic liver injury is fibrosis, with accumulation of extracellular matrix orchestrated by activated hepatic stellate cells (HSCs). Glucocorticoids limit HSC activation in vitro, and tissue glucocorticoid levels are amplified by 11beta-hydroxysteroid dehydrogenase-1 (11βHSD1). Although 11βHSD1 inhibitors have been developed for type 2 diabetes mellitus and improve diet-induced fatty liver in various mouse models, effects on the progression and/or resolution of liver injury and consequent fibrosis have not been characterized. We have used the reversible carbon tetrachloride-induced model of hepatocyte injury and liver fibrosis to show that in two models of genetic 11βHSD1 deficiency (global, Hsd11b1-/- , and hepatic myofibroblast-specific, Hsd11b1fl/fl /Pdgfrb-cre) 11βHSD1 pharmacological inhibition in vivo exacerbates hepatic myofibroblast activation and liver fibrosis. In contrast, liver injury and fibrosis in hepatocyte-specific Hsd11b1fl/fl /albumin-cre mice did not differ from that of controls, ruling out 11βHSD1 deficiency in hepatocytes as the cause of the increased fibrosis. In primary HSC culture, glucocorticoids inhibited expression of the key profibrotic genes Acta2 and Col1α1, an effect attenuated by the 11βHSD1 inhibitor [4-(2-chlorophenyl-4-fluoro-1-piperidinyl][5-(1H-pyrazol-4-yl)-3-thienyl]-methanone. HSCs from Hsd11b1-/- and Hsd11b1fl/fl /Pdgfrb-cre mice expressed higher levels of Acta2 and Col1α1 and were correspondingly more potently activated. In vivo [4-(2-chlorophenyl-4-fluoro-1-piperidinyl][5-(1H-pyrazol-4-yl)-3-thienyl]-methanone administration prior to chemical injury recapitulated findings in Hsd11b1-/- mice, including greater fibrosis.

CONCLUSION

11βHSD1 deficiency enhances myofibroblast activation and promotes initial fibrosis following chemical liver injury; hence, the effects of 11βHSD1 inhibitors on liver injury and repair are likely to be context-dependent and deserve careful scrutiny as these compounds are developed for chronic diseases including metabolic syndrome and dementia. (Hepatology 2018;67:2167-2181).

Human aqueous humor levels of transforming growth factor-β2: Association with matrix metalloproteinases/tissue inhibitors of matrix metalloproteinases

The present study aims to investigate the association of transforming growth factor-β2 (TGF-β2) and matrix metalloproteinases (MMPs), MMP-2 and MMP-3, and tissue inhibitors of matrix metalloproteinases (TIMPs), TIMP-1, TIMP-2 and TIMP-3 in the aqueous humor of patients with high myopia or cataracts. The levels of TGF-β2 and MMPs/TIMPs were measured with the Luminex xMAP Technology using commercially available Milliplex xMAP kits. The association between TGF-β2 and MMPs/TIMPs levels was analyzed using the Spearmans correlation test. The levels of TGF-β2 were identified to be positively correlated with the levels of TIMP-1 and TIMP-3 (TIMP-1: r=0.334; P=0.007; TIMP-3: r=0.309; P=0.012). The levels of MMP-2, MMP-3 and TIMP-2 did not significantly correlate with TGF-β2 levels (P>0.05). A positive correlation was identified between TGF-β2 and TIMPs in the aqueous humor of human eyes with elongated axial length. It appears that TGF-β2 stimulates the expression of TIMPs as a compensatory reaction to the development of high myopia.

Metalloproteinases and their inhibitors are influenced by inhalative glucocorticoid therapy in combination with environmental dust reduction in equine recurrent airway obstruction

Background

Overexpression of matrix-metalloproteinases (MMPs) has been shown to lead to tissue damage in equine recurrent airway obstruction (RAO), as a misbalance with their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), occurs. This favors irreversible pulmonary fibrosis formation. Increased levels of MMPs, TIMPs or altered ratios between them can be used as biomarkers of respiratory disease. We hypothesized that levels of MMPs, TIMPs and their ratios correlate with improvement in clinical findings and bronchoalveolar lavage fluid (BALF) cytology after 10 days of inhalative glucocorticoid therapy and environmental dust reduction (EDR) and may be used to monitor treatment success.

Ten horses with a history of RAO participated in a prospective clinical study. Clinical and cytological scoring was performed before and after inhalative therapy using budesonide (1500 μg BID over 10 days) and EDR (bedding of wood shavings and wet hay as roughage). Gelatin zymography was performed for qualitative and semi-quantitative evaluation of MMP-2 and MMP-9 in BALF supernatant, while fluorimetry was used to evaluate MMP-8 activity. Additionally, specific equine ELISA assays were used for quantitative assessment of MMP-2, MMP-9, TIMP-1 and TIMP-2.

Results

A significant reduction in the total and several single parameters of the clinical score were found after 10 days of inhalative therapy and EDR. The concentrations of MMP-2, MMP-9, TIMP-1 and TIMP-2 (ELISA) as well as their activities (MMP-2 and MMP-9 zymography and MMP-8 fluorimetry) were significantly decreased after therapy. Significant improvements in MMP-8/TIMP-1 and MMP-8/TIMP-2 ratios were also found, differences between other ratios before and after therapy were insignificant.

Conclusions

Metalloproteinases and their inhibitors, in particular MMP-9 and TIMP-2, are valuable markers for clinical improvement in RAO.

Boysenberry ingestion supports fibrolytic macrophages with the capacity to ameliorate chronic lung remodeling

Lung fibrosis negatively impacts on lung function in chronic asthma and is linked to the development of profibrotic macrophage phenotypes. Epidemiological studies have found that lung function benefits from increased consumption of fruit high in polyphenols. We investigated the effect of boysenberry consumption, in both therapeutic and prophylactic treatment strategies in a mouse model of chronic antigen-induced airway inflammation. Boysenberry consumption reduced collagen deposition and ameliorated tissue remodeling alongside an increase in the presence of CD68+CD206+arginase+ alternatively activated macrophages in the lung tissue. The decrease in tissue remodeling was associated with increased expression of profibrolytic matrix metalloproteinase-9 protein in total lung tissue. We identified alternatively activated macrophages in the mice that consumed boysenberry as a source of the matrix metalloproteinase-9. Oral boysenberry treatment may moderate chronic tissue remodeling by supporting the development of profibrolytic alternatively activated macrophages expressing matrix metalloproteinase-9. Regular boysenberry consumption therefore has the potential to moderate chronic lung remodeling and fibrosis in asthma and other chronic pulmonary diseases.

Airway Remodeling in Chronic Obstructive Pulmonary Disease and Asthma: the Role of Matrix Metalloproteinase-9

Chronic obstructive pulmonary disease (COPD) and asthma are both associated with airflow restriction and progressive remodeling, which affect the respiratory tract. Among various biological factors involved in the pathomechanisms of both diseases, proteolytic enzymes--matrix metalloproteinases (MMPs)--play an important role, especially MMP-9. In this review, the authors discuss the current topics of research concerning the possible role of MMP-9 in both mentioned diseases. They include the analysis of protein levels, nucleotide polymorphisms of MMP-9 gene and their possible correlation with asthma and COPD. Finally, the authors refer to the studies on MMP-9 inhibition as a new perspective for increasing the effectiveness of treatment in asthma and COPD.

Asthma therapy and its effect on airway remodelling

Asthma remains a major health problem with significant morbidity, mortality and economic costs. In asthma, airway remodelling, which refers to all the microscopic structural changes seen in the airway tissue, has been recognised for many decades and remains one of the defining characteristics of the disease; however, it is still poorly understood. The detrimental pathophysiological consequences of some features of remodelling, like increased airway smooth muscle mass and subepithelial fibrosis, are well documented. However, whether targeting these by therapy would be beneficial is unknown. Although the prevailing thinking is that remodelling is an abnormal response to persistent airway inflammation, recent evidence, especially from studies of remodelling in asthmatic children, suggests that the two processes occur in parallel. The effects of asthma therapy on airway remodelling have not been studied extensively due to the challenges of obtaining airway tissue in the context of clinical trials. Corticosteroids remain the cornerstone of asthma therapy, and their effects on remodelling have been better studied than other drugs. Bronchial thermoplasty is the only asthma therapy to primarily target remodelling, although how it results in the apparent clinical benefits seen is not exactly clear. In this article we discuss the mechanisms of airway remodelling in asthma and review the effects of conventional and novel asthma therapies on the process.

Dynamic control of Th2 cell responses by STAT3 during allergic lung inflammation in mice

Signal transducer and activator of transcription (STAT) family molecules play essential roles during the differentiation of helper T cells from naïve precursors. Although the role of STAT3 in driving Th17 cell polarization has been well established, its role on Th2 responses to allergens remains incompletely understood. By employing T cell-specific STAT3 deficient mice, we demonstrate that STAT3 in T cells plays diverse role on Th2 cells depending on their locations in an animal model of allergic asthma. In the bronchial lymph nodes, STAT3-deficient T cells produced significantly reduced levels of Th2 cytokines. The frequencies of Th2 cells among CD4(+) T cells in the lung were comparable between STAT3-sufficient and STAT3-deficient T cells. By contrast, STAT3-deficient T cells in the airway exhibited significantly enhanced production of Th2 cell cytokines compared to STAT3-sufficient T cells. Interestingly, a major population of IL-4/5 producers among STAT3-deficient T cells in the airway co-produced IFNγ. The frequency of Th17 cells was significantly diminished whereas that of Th1 cells was increased in all the lung-associated tissues. Our results demonstrate the dynamic and opposing roles of STAT3 during the development of Th2 cells from bronchial lymph nodes to the airway and propose the need of careful consideration on STAT3-targeting approaches for the treatment of lung diseases.

Prolonged Treatment with Inhaled Corticosteroids does not Normalize High Activity of Matrix Metalloproteinase-9 in Exhaled Breath Condensates of Children with Asthma

The airway remodeling in asthma is associated with increased amount of matrix metalloproteinase (MMP)-9. High levels of MMP-9 were found in mucosal biopsies, sputum and in exhaled breath condensates (EBC) of asthma patients. However, there are no data concerning real in vivo activity. Inhaled corticosteroids are effective in asthma control, but it is unclear, whether they only attenuate inflammation, or also protect against progressive remodeling of respiratory tract. Therefore, the aim of the study was to assess the amount and activity of MMP-9 in context of pro-inflammatory cytokines (IL-6, IL-8 and tumor necrosis factor, TNF), measured in EBC of asthma-suffering children, treated with inhaled steroids. The study involved 27 children with asthma, continuously treated with inhaled fluticasone propionate, and 22 healthy controls. In addition to routine clinical screening, the selected cytokines in EBC were analyzed using Ultrasensitive ELISA, whereas activity of MMP-9 was assessed using a novel immunozymography method. Despite chronic treatment with inhaled steroids mean MMP-9/EBC activity in asthma group was significantly higher than in healthy controls. Moreover, high MMP-9/EBC in asthma-suffering children significantly correlated with IgE serum levels. The IL-6 and IL-8 concentration was below the detection limit in all EBC samples. TNF/EBC levels were similar in both, asthma and healthy children. We hypothesize that MMP-9 hyperactivity in asthma may be closely related to high IgE serum levels. Our results suggest that inhaled steroids may be ineffective to prevent asthma-associated airway remodeling. Finally, we emphasize the necessity of further research focused on MMP-9 inhibition in asthma treatment.

Effects of budesonide/formoterol combination therapy versus budesonide alone on airway dimensions in asthma

BACKGROUND AND OBJECTIVE

Combination therapy with inhaled corticosteroids and long-acting β(2)-agonists results in improved asthma symptom control compared with the use of inhaled corticosteroids alone. However, the effects of combination therapy on structural changes and inflammation of the airways are still unknown. The aim of this study was to compare the effects of budesonide/formoterol with those of budesonide alone on airway dimensions and inflammation in individuals with asthma.

METHODS

Fifty asthmatic patients were randomized to treatment with budesonide/formoterol (200/6 µg, two inhalations bd) or budesonide (200 µg, two inhalations bd) for 24 weeks. Airway dimensions were assessed using a validated computed tomography technique, and airway wall area (WA) corrected for body surface area (BSA), percentage WA (WA%), wall thickness/Ösquare root BSA, and luminal area (Ai)/BSA at the right apical segmental bronchus, were measured. The percentage of eosinophils in induced sputum, pulmonary function, and Asthma Quality of Life Questionnaires (AQLQ) were also evaluated.

RESULTS

There were significantly greater decreases in WA/BSA (P < 0.05), WA% (P < 0.001) and wall thickness/square root BSA (P < 0.05), and increases in Ai/BSA (P < 0.05), in subjects treated with budesonide/formoterol compared with those treated with budesonide. The reduction in sputum eosinophils and increase in per cent of predicted forced expiratory volume in 1 s (FEV(1) %) were greater for subjects treated with budesonide/formoterol compared with those treated with budesonide alone. In the budesonide/formoterol group, the changes in WA% were significantly correlated with changes in sputum eosinophils and FEV(1%) (r = 0.84 and r = 0.64, respectively). There were improvements in the AQLQ scores after treatment with budesonide/formoterol.

CONCLUSIONS

Budesonide/formoterol combination therapy is more effective than budesonide alone for reducing airway wall thickness and inflammation in individuals with asthma.

Pin1 protein regulates Smad protein signaling and pulmonary fibrosis

Interstitial pulmonary fibrosis is caused by the excess production of extracellular matrix (ECM) by Fb in response to TGF-β1. Here, we show that the peptidyl-prolyl isomerase Pin1 modulates the production of many pro- and antifibrogenic cytokines and ECM. After acute, bleomycin injury, Pin1(-/-) mice showed reduced, pulmonary expression of collagens, tissue inhibitors of metalloproteinases, and fibrogenic cytokines but increased matrix metalloproteinases, compared with WT mice, despite similar levels of inflammation. In primary fibroblasts, Pin1 was required for TGF-β-induced phosphorylation, nuclear translocation, and transcriptional activity of Smad3. In Pin1(-/-) cells, inhibitory Smad6 was found in the cytoplasm rather than nucleus. Smad6 knockdown in Pin1(-/-) fibroblasts restored TGF-β-induced Smad3 activation, translocation, and target gene expression. Therefore, Pin1 is essential for normal Smad6 function and ECM production in response to injury or TGF-β and thus may be an attractive therapeutic target to prevent excess scarring in diverse lung diseases.

What effect does asthma treatment have on airway remodeling? Current perspectives

Airway remodeling, or structural changes of the airway wall arising from injury and repair, plays an important role in the pathophysiology of asthma. Remodeling is characterized as structural changes involving the composition, content, and organization of many of the cellular and molecular constituents of the bronchial wall. These structural changes can include epithelial injury, subepithelial thickening/fibrosis, airway smooth muscle hyperplasia, goblet cell hypertrophy and hyperplasia, and angiogenesis. Historically, these changes are considered a consequence of long-standing airway inflammation. Recent infant and child studies, however, suggest that remodeling occurs in parallel with inflammation in asthmatic subjects. Despite advancements in the recognition of key cellular and molecular mechanisms involved in remodeling, there remains a paucity of information about which treatments or interactions are most likely to regulate these processes. Furthermore, it is unclear as to when is the best time to initiate treatments to modify remodeling, which components to target, and how best to monitor interventions on remodeling. Indeed, inhaled corticosteroids, which are generally considered to have limited influence on remodeling, have been shown to be beneficial in studies in which the dose and duration of treatment were increased and prolonged, respectively. Moreover, several studies have identified the need to identify novel asthma indices and phenotypes that correlate with remodeling and, as a consequence, might specifically respond to new therapies, such as anti-IgE, anti-IL-5, and anti-TNF-α mAbs. Our review will evaluate the development of remodeling in asthmatic subjects and the effects of treatment on these processes.

TGFβ-induced matrix production by bronchial fibroblasts in asthma: budesonide and formoterol effects

To investigate the mechanisms of enhanced airway deposition of subepithelial collagen in asthma and its sensitivity to drug therapy with combination of an inhaled glucocorticosteroid (GC) and a long-acting β(2)-agonist (LABA), a cell model system involving bronchial fibroblasts derived from biopsies from patients with stable mild-to-moderate asthma has been used. To mimic unstable conditions and severe asthma, fibroblasts were stimulated ex vivo with TGFβ1. Primary fibroblasts established from central bronchial biopsies from 8 asthmatic patients were incubated for 24 h with 0.4% serum or TGFβ1 (10 ng/ml) with/without the GC budesonide (BUD; 10 nM) and/or the LABA formoterol (FORM; 0.1 nM). Procollagen peptide I (PICP), metalloproteinase (MMP)-1 and tissue inhibitor of MMPs (TIMP-1) were determined in culture media using ELISA while the activity of MMP-2, -3, -9 by zymography. Metabolically labeled proteoglycans, biglycan and decorin, associated with collagen fibrillation/deposition, were separated using chromatography and SDS-PAGE. The levels of PICP and biglycan were increased 2-fold by TGFβ1 (p < 0.05). The BUD and FORM combination reduced the PICP increase by 58% (p < 0.01) and the biglycan by 36% (p < 0.05) while each drug alone had no effect. Decorin levels were reduced by TGFβ1 in fibroblasts of most patients; BUD alone and BUD and FORM completely counteracted this decrease. MMPs and TIMP-1 were not affected by TGFβ1 or the drugs. These results suggest that BUD and FORM combination therapy, without affecting metalloproteolytic balance, has a potential to counteract enhanced collagen production by bronchial fibroblasts in asthma and to normalize the production of small proteoglycans which may affect collagen fibrillation and deposition.

Relationship between matrix production by bronchial fibroblasts and lung function and AHR in asthma

The reasons for enhanced deposition of extracellular matrix in the airways of asthmatic patients and the subsequent consequences on lung function are uncertain. Here, we investigated the synthesis of procollagen I and proteoglycans, the activity of various metalloproteinases (MMPs) and the production of their inhibitor TIMP-1 in biopsy-derived bronchial fibroblasts from eight patients with stable mild-to-moderate asthma, and how they are related to patients' lung function and airway hyperreactivity (AHR). Following 24-h fibroblast incubation in 0.4% serum, procollagen I carboxyterminal propeptide (PICP), TIMP-1 and MMP-1 in cell media were analysed by ELISA, MMP-2, MMP-3, MMP-9 by zymography and total proteoglycan production by [(35)S]-sulphate-incorporation/ion chromatography. Patients' FEV(1)% predicted and methacholine log PD(20) negatively correlated with PICP synthesized by patients' bronchial fibroblasts (r = -0.74 and r = -0.71, respectively). PICP and proteoglycan amounts positively correlated (0.8 ≤ r ≤ 0.9) with MMP-2 and MMP-3 activity. A positive correlation (r = 0.75) was also found between proteoglycan production and TIMP-1. There was no correlation between MMP-9 activity and PICP or proteoglycan production. MMP-9 activity positively correlated with patients' FEV(1)% predicted (r = 0.97) and methacholine log PD(20) (r = 0.86), whereas negative associations (-0.6 ≤ r ≤ -0.7) were observed for MMP-2 and MMP-3. In stable mild-to-moderate asthma, increased procollagen I synthesis and activity of MMP-2 and MMP-3 in bronchial fibroblasts may negatively affect patients' lung function and AHR. In contrast, MMP-9 activity was not associated with procollagen or proteoglycan production, or worsening of patients' lung function and AHR. An enhanced production of procollagen I and proteoglycans might be a result of a negative feedback from their degradation by MMP-2 and MMP-3.