Increase In Lung Hydroxyproline Content Research Articles

A therapeutic role for mesenchymal stem cells in acute lung injury independent of hypoxia‐induced mitogenic factor

Bone marrow mesenchymal stem cells (BM-MSCs) have therapeutic potential in acute lung injury (ALI). Hypoxia-induced mitogenic factor (HIMF) is a lung-specific growth factor that participates in a variety of lung diseases. In this study, we evaluated the therapeutic role of BM-MSC transplantation in lipopolysaccharide (LPS)- induced ALI and assessed the importance of HIMF in MSC transplantation. MSCs were isolated and identified, and untransduced MSCs, MSCs transduced with null vector or MSCs transduced with a vector encoding HIMF were transplanted into mice with LPS-induced ALI. Histopathological changes, cytokine expression and indices of lung inflammation and lung injury were assessed in the various experimental groups. Lentiviral transduction did not influence the biological features of MSCs. In addition, transplantation of BM-MSCs alone had significant therapeutic effects on LPS-induced ALI, although BM-MSCs expressing HIMF failed to improve the histopathological changes observed with lung injury. Unexpectedly, tumour necrosis factor α levels in lung tissues, lung oedema and leucocyte infiltration into lungs were even higher after the transplantation of MSCs expressing HIMF, followed by a significant increase in lung hydroxyproline content and α-smooth muscle actin expression on day 14, as compared to treatment with untransduced MSCs. BM-MSC transplantation improved LPS-induced lung injury independent of HIMF.

Simvastatin attenuates experimental small airway remodelling in rats

The aim of this study was to assess the beneficial effects of simvastatin on cigarette smoke-induced small airway remodeling in rats. Simvastatin was administered at different doses for 16 weeks to rats with cigarette smoke-induced small airway remodelling. Morphological analyses were performed, and collagen deposition, production of growth factors, inflammatory parameters and RhoA, as well as the Smad signalling pathway in the lungs, were examined. Simvastatin attenuated small airway wall thickening and prevented the increase in lung hydroxyproline content and collagen deposition induced in airway walls by cigarette smoking. In addition, simvastatin downregulated transforming growth factor-beta1 and connective tissue growth factor protein and gene expression in the lungs. Furthermore, accumulation of macrophages and neutrophils and increases in tumour necrosis factor-alpha concentration in BAL fluid were inhibited by simvastatin. Simultaneously, the expression of RhoA and the phosphorylation of Smad2 and Smad3 in lungs exposed to cigarette smoke were inhibited during simvastatin administration. However, the increased expression of Smad2 and Smad3 proteins and the decreased level of Smad7 protein in remodelled lungs were not affected by simvastatin. Simvastatin attenuated experimental small airway remodelling, as indicated by decreases in collagen deposition and small airway wall thickening. Simvastatin may inhibit cigarette smoke-induced small airway remodelling by reducing growth factor expression and inflammation. The mechanism of action of simvastatin on small airway remodelling involved RhoA and the Smad signalling pathway. These findings indicate that simvastatin may have potential beneficial effects in the treatment of COPD.

Curcumin inhibition of bleomycin-induced pulmonary fibrosis in rats.

Curcumin, an anti-inflammatory, antioxidant, was evaluated for its ability to suppress bleomycin (BLM)-induced pulmonary fibrosis in rats. A single intratracheal instillation of BLM (0.75 U 100(-1) g, sacrificed 3, 5, 7, 14 and 28 days post-BLM) resulted in significant increases in total cell numbers, total protein, and angiotensin-converting enzyme (ACE), and alkaline phosphatase (AKP) activities in bronchoalveolar lavage fluid. Animals with fibrosis had a significant increase in lung hydroxyproline content. Alveolar macrophages from BLM-administered rats elaborated significant increases in tumour necrosis factor (TNF)-alpha release, and superoxide and nitric oxide production in culture medium. Interestingly, oral administration of curcumin (300 mg kg(-1) 10 days before and daily thereafter throughout the experimental time period) inhibited BLM-induced increases in total cell counts and biomarkers of inflammatory responses in BALF. In addition, curcumin significantly reduced the total lung hydroxyproline in BLM rats. Furthermore, curcumin remarkably suppressed the BLM-induced alveolar macrophage production of TNF-alpha, superoxide and nitric oxide. These findings suggest curcumin as a potent anti-inflammatory and anti-fibrotic agent against BLM-induced pulmonary fibrosis in rats.

DEXAMETHASONE PROTECTS HAMSTERS FROM FIBROSIS BUT NOT INFLAMMATION INDUCED BY INTRATRACHEAL AMIODARONE

The antiarrhythmic drug amiodarone (AD) m ay cause severe lung damage in human patients. Often these patients are treated with corticosteroids; the usefulness of steroids in alleviating AD-induced lung disease has never been adequately studied, however. Intratracheal instillation of AD to hamsters causes pulmonary inflammation and fibrosis. The objective of this study was to examine whether corticosteroid treatment protects hamsters from AD-induced pulm onary inflammation and fibrosis. Male Syrian ham sters were treated with dexamethasone or saline and then instilled with AD or saline. Dexam ethasone treatm ent blocked the AD-induced increase in lung hydroxyproline content, an index of fibrosis. Analysis of bronchoalveolar lavage fluid showed that dexamethasone partially blocked AD-induced increases in total cells, m acrophages, and eosinophils. Dexam ethasone did not protect against the increase in neutrophils associated with AD treatm ent; neutrophil influx is widely utilized as a marker of inflamm ation. Dexam ethasone also failed to block the increase in lavage fluid albumin resulting from AD treatment; albumin in lavage fluid is considered an index of alveolar-capillary permeability. This study demonstrates that dexamethasone prevents AD-induced pulmonary fibrosis in hamsters while having m inim al effects on inflam mation.

T lymphocytes and silica-induced pulmonary inflammation and fibrosis in mice.

Silica-induced pulmonary inflammation and fibrosis in animals provides a good model for chronic pulmonary inflammation and fibrosis. Although lymphocytes are implicated in the pathogenesis of pulmonary fibrosis, experimental models using silica-treated athymic nude mice have not been successful in showing the fibrogenic mechanism regulated by T cells. The aim of this study was to re-evaluate the role of T lymphocytes in the development of silicosis by comparing the response to silica administration of nude athymic mutants with that of euthymic animals. Suspensions of silica particles were transnasally administered to nude athymic mice (Balb/c nu/nu) as well as to their euthymic littermates (Balb/c nu/+). The degree of pulmonary inflammation and fibrosis was assessed on days 14, 28, and 56 based upon histological observation, analysis of collagen deposition in the lungs, and analysis of the cellular constituent, protein, and phospholipid content in the bronchoalveolar lavage fluid. Histologically, athymic mice developed less severe interstitial pneumonitis than euthymic mice. In euthymic mice the lung hydroxyproline content increased with time after silica administration from 6.48 (0.38) micrograms hydroxyproline/mg dry lung weight on day 0 to 8.87 (0.41) micrograms/mg on day 56. A gradual increase in lung hydroxyproline content was also observed in athymic mice but the increase was significantly smaller than in euthymic mice (6.63 (0.43) micrograms/mg on day 0, 7.90 (0.19) micrograms/mg on day 56). Administration of silica resulted in an increase in the number of macrophages and neutrophils and in the total protein and phospholipid content of the bronchoalveolar lavage (BAL) fluid in both mouse strains. No significant difference was detected between athymic and euthymic mice in the numbers of macrophages, but the increase in neutrophils in the BAL fluid of athymic mice was significantly smaller than in euthymic mice on days 14 and 56. The total protein and phospholipid content of the BAL fluid from athymic mice was lower than that from euthymic mice. T lymphocytes appear to be involved in the pathogenesis of silica-induced pneumonitis. Since pulmonary fibrosis develops even in nude athymic mice, T cells do not seem to play a primary part in fibrogenic response but they regulate, at least to some extent, the response of inflammatory cells and fibrogenesis of the lung.

Monocrotaline-induced cardiopulmonary injury in rats: Modification by the neutrophil elastase inhibitor SC39026

Rats were killed after 6 weeks of continuous ingestion of the pneumotoxic alkaloid monocrotaline (2.2mg/kg/day), the neutrophil elastase inhibitor SC39026 (60mg/kg/day), or both. Pulmonary reactions were evaluated by light and electron microscopy. Lung endothelial function was monitored by angiotensin converting enzyme (ACE) activity, plasminogen activator (PLA) activity, and prostacyclin (PGI 2) and thromboxane (TXA 2) production. Lung hydroxyproline content was measured as an index of interstitial fibrosis. Cardiac right ventricular hypertrophy was determined by the right ventricle to the left ventricle plus septum weight ratio (RV/LV + S). Rats receiving SC39026 alone did not differ significantly from untreated control animals with respect to any of the quantitative endpoints, although rarefaction of Type I pneumocytes was observed in the electron micrographs of these animals. Monocrotaline-treated rats, in contrast, developed a significant increase in RV/LV + S, and exhibited pulmonary edema, inflammation, fibrosis, and muscularization and occlusive mural thickening of the pulmonary small arteries and arterioles. These monocrotaline-induced structural changes were accompanied by decreased lung ACE and PLA activities, and increased PGI 2 and TXA 2 production, and by an increase in lung hydroxyproline content. Cotreatment with SC39026 ameliorated the monocrotaline-induced pulmonary vascular wall thickening and the cardiac right ventricular hypertrophy. These data suggest that inappropriate neutrophil elastase activity contributes to monocrotaline pulmonary vasculopathy and hypertension. On the other hand, cotreatment with SC39026 had no significant effect on the severity of the monocrotaline-induced lung inflammatory reaction, the pulmonary endothelial dysfunction, or the increase in lung hydroxyproline content.

Bleomycin and cyclophosphamide toxicity in mice with damaged lung tissue

The clinical use of several anticancer drugs, including bleomysin and cyclophosphamide (CP), is often associated with lung damage which progresses to fibrosis. The effect of existing lung damage on the toxicity of these agents has not been investigated. Male BALB/c mice were treated intraperitoneally with 400 mg/kg butylated hydroxytoluene (BHT), 100 mg/kg CP or 100 mg/kg bleomycin, alone or in combination. Based on analyses of pulmonary DNA synthesis, each agent alone elicited significant lung damage with cell proliferation, peaking on Day 4 for BHT, Day 7 for CP and Day 14 for bleomycin. Quantitatively, the BHT lesion was greater than CP which was much greater than bleomycin. Mice given 100, 75, 50, 40 or 25 mg/kg bleomysin 1 day after BHT exhibited 100, 90, 22, 20 and 21% mortality, respectively. Treatment with 100, 50, 40 or 25 mg/kg CP 1 day after BHT resulted in 100, 54, 33 and 0% mortality, respectively. No mice treated with BHT, bleomycin or CP alone died. Total lung hydroxyproline content, an index of fibrosis, was significantly increased 14 days after the initial treatment in mice given BHT and 50 mg/kg bleomycin compared to mice treated with BHT, bleomycin or vehicle alone. Mice treated with 50 mg/kg CP 1 day after BHT did not develop fibrosis in excess of that attributable to the BHT alone. Treatment of mice with 100 mg/kg CP followed 1 or 2 days later by 100 mg/kg bleomycin resulted in 20–40% mortality, but no increase in lung hydroxyproline content compare to CP alone. Bleomycin delayed the onset of lung cell proliferation normally seen after treatment with BHT while CP attenuated this cell division only after it had begun. Treatments involving BHT and bleomycin did not alter lung sulfhydryl content. These data indicate that overall toxicity is increased in mice pretreated with BHT and then given bleomycin or CP while lung injury is enhanced only after bleomycin. The mechanism of the interaction with bleomycin is not known but may be related to a rapid inhibition of lung repair and not to oxidative stress.

Monocrotaline-induced cardiopulmonary damage in rats: amelioration by the angiotensin-converting enzyme inhibitor CL242817.

Pulmonary injury induced by the plant alkaloid monocrotaline is partially prevented by the angiotensin-converting enzyme (ACE) inhibitor captopril. CL242817 [(S-[R*,S*])-1-([3-acetylthio]-3-benzoyl-2-methyl-propionyl)- L-proline] is a new orally active ACE inhibitor under evaluation as an antihypertensive agent. To determine whether CL242817 also can modify monocrotaline-induced pulmonary injury, male rats were divided into four groups: control; CL242817 (60 mg/kg/day, po); monocrotaline (2.4 mg/kg/day, po); or monocrotaline plus CL242817, and were sacrificed after 6 weeks of continuous treatment. Rats receiving monocrotaline alone exhibited occlusive medial thickening of the pulmonary arteries, cardiomegaly, and right ventricular hypertrophy. Electron micrographs of monocrotaline-treated lung revealed degeneration of both endothelial and Type I epithelial cells, as well as marked interstitial hypercellularity and fibrosis. Hydroxyproline (collagen) content of monocrotaline-treated lung also increased significantly, confirming the fibrosis observed in the electron micrographs. These structural changes were accompanied by decreased lung ACE and plasminogen activator (PLA) activities, indicative of pulmonary endothelial dysfunction. Concomitant CL242817 treatment ameliorated all anatomic manifestations of monocrotaline injury, particularly the right ventricular hypertrophy, pulmonary arterial occlusion, epithelial degeneration, and interstitial fibrosis. CL242817 also significantly prevented the monocrotaline-induced increase in lung hydroxyproline content. In contrast, concomitant CL242817 did not significantly influence the suppressed lung ACE and PLA activities in monocrotaline-treated rats. CL242817 alone produced retarded weight gain, decreased heart weight relative to body weight, decreased lung hydroxyproline content and ACE activity, and increased serum ACE activity and plasma AII concentration. Thus CL242817 resembles captopril, both in its ability to ameliorate monocrotaline-induced pulmonary injury in rats, and in many of its side effects.

Pulmonary endothelial dysfunction in the presence or absence of interstitial injury induced by intratracheally injected bleomycin in rabbits.

Previously, we reported that repeated subcutaneous administration of bleomycin (BLM) to rabbits produced functional and structural endothelial damage with no evidence of interstitial fibrosis. In the present study, rabbits received intratracheally a single injection of BLM (6 units/kg, n = 6: "low dose" or 11 units/kg, n = 4: "high dose"); 6 additional animals received intratracheally an injection of saline and served as controls. Four weeks after BLM administration, the low-dose group demonstrated significant reduction in the single-pass pulmonary removal of 14C-5-hydroxytryptamine (5-HT) (p less than 0.05; n = 4), whereas 3H-norepinephrine (NE) removal and 3H-benzoyl-phe-ala-pro (BPAP) substrate for lung angiotensin converting enzyme (ACE) metabolism in vivo, as well as lung and serum ACE activity in vitro remained at control levels. No morphologic or biochemical evidence of fibrosis was observed. In contrast, the high-dose BLM group exhibited significant reductions in 14C-5-HT and 3H-NE removal and 3H-BPAP metabolism in vivo, but no significant changes in lung or serum ACE activity in vitro. Furthermore, there was evidence of fibrosis, as revealed by a 59% increase in lung hydroxyproline content and by light microscopic examination of lung tissue. We conclude that intratracheal administration of BLM to rabbits can produce endothelial dysfunction in the presence or absence of interstitial injury.