Transforming growth factor-beta: a mediator of cell regulation in acute respiratory distress syndrome

Design, synthesis, and evaluation of pirfenidone-NSAIDs conjugates for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal, chronic and progressive lung disease that threaten public health like many cancers. In this study, targeting the significant driving factor, inflammatory response, of the IPF, several conjugates of pirfenidone (PFD) with non-steroidal anti-inflammatory drugs (NSAIDs), along with their derivatives, were designed and synthesized to enhance the anti-IPF potency of PFD. Among these compounds, the (S)-ibuprofen-PFD conjugate 5b exhibited the most potent anti-proliferation activity against NIH3T3 cells, demonstrating up to a 343-fold improvement compared to PFD (IC50 = 0.04 mM vs IC50 = 13.72 mM). Notably, 5b exhibited superior activity in inhibiting the migration of macrophages induced by TGF-β compared to PFD. Additionally, 5b demonstrated significant suppression of TGF-β-induced migration of NIH3T3 cells and induction of apoptosis in NIH3T3 cells. Mechanistic studies revealed that 5b reduced the expression of collagen I and α-SMA by inhibiting the TGF-β/SMAD3 pathway. In a bleomycin-induced pulmonary fibrosis model, treatment with 5b (40 mg/kg/day, orally) exhibited a more pronounced effect on reducing the degree of histopathological changes in lung tissue and alleviating collagen deposition compared to PFD (100 mg/kg/day, orally). Moreover, 5b could block the expression of collagen I, α-SMA, fibronectin, and pro-inflammatory factors (IL-6, IFN-γ, and TNF-α) compared to PFD, while demonstrating low toxicity in vivo. These preliminary results indicated that the hybridization of PFD with NSAIDs represented an effective modification approach to improve the anti-IPF potency of PFD. Consequently, 5b emerged as a promising candidate for the further development of new anti-IPF agents.

Design, synthesis and evaluation of novel UDCA-aminopyrimidine hybrids as ATX inhibitors for the treatment of hepatic and pulmonary fibrosis

To discover novel anti-fibrotic agents, a series of UDCA-aminopyrimidine hybrids were designed and synthesized as potent ATX inhibitors by molecular hybridization strategy. The ATX inhibitory activities of all synthesized compounds were evaluated using the LPC choline release assay. The preliminary structure-activity relationship was concluded. Among them, 12a and 12h exhibited the strongest ATX inhibitory activities with IC50 values of 7.62 ± 0.62 and 7.51 ± 0.72 nM respectively, which were 9-fold more effective than the positive control drug GLPG-1690. Molecular docking studies revealed that 12a and 12h occupied the hydrophobic pocket and tunnel of the ATX binding site. The cytotoxicity assay of 12a and 12h revealed that they had no obvious toxicity at concentrations up to 80 μM, therefore their anti-hepatic fibrosis and anti-pulmonary fibrosis activities were further investigated. The results suggested that 12a and 12h significantly decreased the gene and protein expression of α-SMA, COL1A1 and FN in both TGF-β1-induced HSC-LX2 and CCC-HPF-1 cells. In addition, 12a and 12h significantly inhibited cells migration in both TGF-β1-induced HSC-LX2 and CCC-HPF-1 cells. Preliminary mechanistic studies indicated that 12a and 12h exerted anti-hepatic fibrosis and anti-pulmonary fibrosis effects by inhibiting the TGF-β/Smad signaling pathway. Overall, our findings suggested that 12a and 12h might be two promising anti-fibrotic agents, or might serve as two new lead compounds for the further development of anti-fibrotic agents.

Resolution of inflammation in xenobiotic-induced mucosal injury and chronic disease

It has been appreciated for decades that exposure to toxicants can induce injury and inflammation leading to multiple pathologies in many organ systems. However, recently the field has begun to recognize that toxicants can cause chronic pathologies and diseases by impairing processes known to promote the resolution of inflammation. This process is comprised of dynamic and active responses including pro-inflammatory mediator catabolism, dampening of downstream signaling, production of pro-resolving mediators, apoptosis, and efferocytosis of inflammatory cells. These pathways promote the return to local tissue homeostasis and prevent chronic inflammation that can lead to disease. The aim of this special issue was to identify and report on the potential hazards of toxicant exposure on the resolution of inflammation responses. Papers included in the issue also provide insights into biological mechanisms by which toxicants perturb these resolution processes and identify potential therapeutic targets.

In vitro and vivo study of tranilast protects from acute respiratory distress syndrome and early pulmonary fibrosis induced by smoke inhalation

BACKGROUND

Tranilast (N-[3＇,4＇-dimethoxycinnamoyl]-anthranilic acid) is an analog of a tryptophan metabolite. It was identified with anti-inflammatory and antifibrotic activities, and used in the treatment of a variety of diseases, such as anti - allergy, bronchial asthma, and hypertrophic scars. As a drug with few adverse reactions, tranilast has attracted great attention, but its application is limited due to the uncertainty of dosages and mechanisms. In this study, the protection effects of different doses of tranilast on smoke inhalation mediated lung injury on rats, and on the damage of three kinds of lung cells in vitro were investigated.

METHOD

In vivo, Sprague-Dawley rats were randomly divided into sham group, smoke group (rats were exposed to pine sawdust smoke three times, each time for 5 min), different doses of tranilast treatment group (doses were 100 mg/kg, 200 mg/kg and 300 mg/kg, ip.) and placebo group. After 1, 3 and 7 days, pulmonary function, pathologic injury by HE staining, cytokines and oxidative stress level by kits were determined. At 7days, lung fibrosis was assessed by Masson's trichrome staining and the level of hydroxyproline (HYP). In vitro, three kinds of lung cells from normal rats were isolated: type II alveolar epithelial cells (AT-II), pulmonary microvascular endothelial cells (PMVECs) and pulmonary fibroblasts (PFs). To investigate the potential effects of tranilast on cell proliferation, cell cycle and cytokine production of three kinds of lung cells exposed to smoke.

RESULTS

Compared with smoke group and placebo group, tranilast treatment significantly reduced histopathological changes (such as pulmonary hemorrhage, edema and inflammatory cell infiltration, etc.), significantly reduced histopathological score (p < 0.05), increased arterial oxygen partial pressure, and decreased the levels of IL-1β, TNF-α, TGF-β1 (p < 0.05), oxidative stress and the expression of nuclear transcription factor κB (NF-κB) smoke exposed rats (p < 0.01). In particular, the effect of 200 mg/kg dose was more prominent. In vitro, smoke induced AT-II and PMVECs apoptosis, improved PFs proliferation (p < 0.01), activity of SOD and decreased the content of MDA (p < 0.01). However, tranilast seems to be turning this trend well. The inflammatory factor IL-11β, TNF-α and TGF-β1, and the expression of NF-κB were significantly lower in the tranilast treatment than in the smoke group (p < 0.01).

CONCLUSION

This study indicates that tranilast had a protective effect on acute respiratory distress syndrome and early pulmonary fibrosis of rats in vivo. In addition, tranilast promotes proliferation of AT-II and PMVECs but inhibits PFs proliferation, down-regulates secretion of inflammatory cytokines and alleviates oxidative stress of AT-II, PMVECs and PFs after smoke stimuli in vitro.

Synthesis and structure–activity relationships of pirfenidone derivatives as anti-fibrosis agents in vitro

Pirfenidone (PFD) was the first approved drug by FDA for the treatment of idiopathic pulmonary fibrosis (IPF). However, the rapid metabolism of 5-methyl of PFD increases the risk of side...

In well-differentiated primary human bronchial epithelial cells, TGF-1 and TGF-2 induce expression of furin

The COVID-19 pandemic is an ongoing threat to public health. Since the identification of COVID-19, the disease caused by SARS-CoV-2, no drugs have been developed to specifically target SARS-CoV-2. To develop effective and safe treatment options, a better understanding of cellular mechanisms underlying SARS-CoV-2 infection is required. To fill this knowledge gap, researchers require reliable experimental systems that express the host factor proteins necessary for the cellular entry of SARS-CoV-2. These proteins include the viral receptor, angiotensin-converting enzyme 2 (ACE2), and the proteases, transmembrane serine protease 2 (TMPRSS2) and furin. A number of studies have reported cell-type-specific expression of the genes encoding these molecules. However, less is known about the protein expression of these molecules. We assessed the suitability of primary human bronchial epithelial (HBE) cells maintained in an air-liquid interface (ALI) as an experimental system for studying SARS-CoV-2 infection in vitro. During cellular differentiation, we measured the expression of ACE2, TMPRSS2, and furin over progressive ALI days by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), Western blot, and immunofluorescence staining. We also explored the effect of the fibrotic cytokine TGF-β on the expression of these proteins in well-differentiated HBE cells. Like ACE2, TMPRSS2 and furin proteins are localized in differentiated ciliated cells, as confirmed by immunofluorescence staining. These data suggest that well-differentiated HBE cells maintained in ALI are a reliable in vitro system for investigating cellular mechanisms of SARS-CoV-2 infection. We further identified that the profibrotic mediators, TGF-β1 and TGF-β2, increase the expression of furin, which is a protease required for the cellular entry of SARS-CoV-2.

Genetic determinants of ammonia-induced acute lung injury in mice

In this study, a genetically diverse panel of 43 mouse strains was exposed to ammonia, and genome-wide association mapping was performed employing a single-nucleotide polymorphism (SNP) assembly. Transcriptomic analysis was used to help resolve the genetic determinants of ammonia-induced acute lung injury. The encoded proteins were prioritized based on molecular function, nonsynonymous SNP within a functional domain or SNP within the promoter region that altered expression. This integrative functional approach revealed 14 candidate genes that included Aatf, Avil, Cep162, Hrh4, Lama3, Plcb4, and Ube2cbp, which had significant SNP associations, and Aff1, Bcar3, Cntn4, Kcnq5, Prdm10, Ptcd3, and Snx19, which had suggestive SNP associations. Of these genes, Bcar3, Cep162, Hrh4, Kcnq5, and Lama3 are particularly noteworthy and had pathophysiological roles that could be associated with acute lung injury in several ways.

Effects of tacrolimus on the TGF‑β1/SMAD signaling pathway in paraquat‑exposed rat alveolar type II epithelial cells

Paraquat is a highly toxic pesticide, which often causes pulmonary interstitial fibrosis after poisoning, and there is no specific antidote. At present, limited studies have reported that tacrolimus, as an immunosuppressant, can inhibit pulmonary fibrosis, but the specific mechanism remains unknown. The aim of the present study was to demonstrate the effect of tacrolimus on the TGF-β1 pathway associated with pulmonary fibrosis in paraquat exposed alveolar type II epithelial cells, and to identify the antipulmonary fibrosis mechanism of tacrolimus The rat alveolar epithelial type II RLE-6TN cell line was exposed to paraquat and treated with or without tacrolimus for 24 h, or with a TGF-β1 receptor type I/II inhibitor (LY2109761) for 1, 4, 8 or 16 h. MTT assays were used to detect the viability of rat alveolar type II epithelial cells under these different treatment conditions, while the concentrations of TGF-β1, SMAD3, SMAD7 and connective tissue growth factor (CTGF) in the cell culture supernatant were determined using ELISAs. Additionally, reverse transcription-quantitative PCR and immunofluorescence were used to analyze the mRNA and protein expression levels of TGF-β1, SMAD3, CTGF and SMAD7. The results demonstrated that the inhibition of the proliferation of RLE-6TN cells exposed to 200 nmol/l paraquat was 26.05±2.99%. The inhibition rate of 10 ng/ml tacrolimus on paraquat-exposed alveolar type II epithelial cells was 18.40±3.49%. The inhibition rate caused by 5 µmol/l LY2109761 was 26.56±4.49%. The expression levels of TGF-β1, SMAD3 and CTGF, as well as their concentrations in the culture supernatant, were significantly downregulated in the tacrolimus group compared with the paraquat group. However, both the concentration and expression levels of SMAD7 were significantly upregulated in the tacrolimus group compared with the paraquat group. In conclusion, tacrolimus can reduce the levels of TGF-β1, SMAD3 and CTGF, increase the level of SMAD7 in TGF-β1 signaling pathway and protect the development of pulmonary fibrosis in paraquat exposed alveolar epithelial cells.

Potential effects of curcumin in the treatment of COVID-19 infection

Coronavirus disease 2019 (COVID-19) outbreak is an ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with considerable mortality worldwide. The main clinical manifestation of COVID-19 is the presence of respiratory symptoms, but some patients develop severe cardiovascular and renal complications. There is an urgency to understand the mechanism by which this virus causes complications so as to develop treatment options. Curcumin, a natural polyphenolic compound, could be a potential treatment option for patients with coronavirus disease. In this study, we review some of the potential effects of curcumin such as inhibiting the entry of virus to the cell, inhibiting encapsulation of the virus and viral protease, as well as modulating various cellular signaling pathways. This review provides a basis for further research and development of clinical applications of curcumin for the treatment of newly emerged SARS-CoV-2.

Immunity-and-matrix-regulatory cells derived from human embryonic stem cells safely and effectively treat mouse lung injury and fibrosis

Lung injury and fibrosis represent the most significant outcomes of severe and acute lung disorders, including COVID-19. However, there are still no effective drugs to treat lung injury and fibrosis. In this study, we report the generation of clinical-grade human embryonic stem cells (hESCs)-derived immunity- and matrix-regulatory cells (IMRCs) produced under good manufacturing practice requirements, that can treat lung injury and fibrosis in vivo. We generate IMRCs by sequentially differentiating hESCs with serum-free reagents. IMRCs possess a unique gene expression profile distinct from that of umbilical cord mesenchymal stem cells (UCMSCs), such as higher expression levels of proliferative, immunomodulatory and anti-fibrotic genes. Moreover, intravenous delivery of IMRCs inhibits both pulmonary inflammation and fibrosis in mouse models of lung injury, and significantly improves the survival rate of the recipient mice in a dose-dependent manner, likely through paracrine regulatory mechanisms. IMRCs are superior to both primary UCMSCs and the FDA-approved drug pirfenidone, with an excellent efficacy and safety profile in mice and monkeys. In light of public health crises involving pneumonia, acute lung injury and acute respiratory distress syndrome, our findings suggest that IMRCs are ready for clinical trials on lung disorders.

Design, synthesis and discovery of 2(1H)-quinolone derivatives for the treatment of pulmonary fibrosis through inhibition of TGF-β/smad dependent and independent pathway

Idiopathic pulmonary fibrosis (IPF) is a progressive, life-threatening and interstitial lung disease with the median survival of only 3-5 years. However, due to the unclear etiology and problems in accurate diagnosis, up to now only two drugs were approved by FDA for the treatment of IPF and their outcome responses are limited. Numerous studies have shown that TGF-β is the most important cytokine in the development of pulmonary fibrosis and plays a role through its downstream signaling molecule TGF-binding receptor Smads protein. In this paper, compounds bearing 2(1H)-quinolone scaffold were designed and their anti-fibrosis effects were evaluated. Of these compounds, 20f was identified as the most active one and could inhibit TGF-β-induced collagen deposition of NRK-49F cells and mouse fibroblasts migration with comparable activity and lower cytotoxicity than nintedanib in vitro. Further mechanism studies indicated that 20f reduced the expression of fibrogenic phenotypic protein α-SMA and collagen Ⅰ by inhibiting the TGF-β/Smad dependent pathways and ERK1/2 and p38 pathways. Moreover, compared with the nintedanib, 20f (100 mg/kg/day, p.o) more effectively alleviated collagen deposition in lung tissue and delayed the destruction of lung tissue structure both in bleomycin-induced prevention and treatment mice pulmonary fibrosis models. The immunohistochemical experiments further showed that 20f could block the expression level of phosphorylated Smad3 in the lung tissue cells, which resulted in its anti-fibrosis effects in vivo. In addition, 20f demonstrated good bioavailability (F = 41.55% vs 12%, compare with nintedanib) and an appropriate elimination half-life (T_1/2 = 3.5 h), suggesting that 20f may be a potential drug candidate for the treatment of pulmonary fibrosis.

Management of Acute Kidney Injury in the Setting of Acute Respiratory Distress Syndrome: Review Focusing on Ventilation and Fluid Management Strategies

Acute respiratory distress syndrome (ARDS) is a major cause of mortality in adults with acute hypoxic respiratory failure and can predispose those afflicted to develop acute kidney injury (AKI). In the setting where AKI and ARDS overlap, incidence of mortality, length of intensive care unit stay, and complexity of management increases drastically. Lung protective ventilation strategy and conservative fluid management are the main focus of therapy in patients with ARDS, but have major implications on renal function. This review aims to provide concise discussion of pathophysiology, ventilation, and fluid management strategies as it relates to AKI in the setting of ARDS.

Regulatory mechanism of NOV/CCN3 in the inflammation and apoptosis of lung epithelial alveolar cells upon lipopolysaccharide stimulation

Lipopolysaccharide (LPS) induces inflammatory stress and apoptosis. Pulmonary epithelial cell apoptosis has been shown to accelerate the progression of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), and is the leading cause of mortality in patients with ALI/ARDS. Nephroblastoma overexpressed (NOV; also known as CCN3), an inflammatory modulator, is reported to be a biomarker in ALI. Using an LPS-induced ALI model, we investigated the expression of CCN3 and its possible molecular mechanism involved in lung alveolar epithelial cell inflammation and apoptosis. Our data revealed that LPS treatment greatly increased the level of CCN3 in human lung alveolar type II epithelial cells (A549 cell line). The A549 cells were also transfected with a specific CCN3 small interfering RNA (siRNA). CCN3 knockdown not only largely attenuated the expression of inflammatory cytokines, interleukin (IL)-1β and transforming growth factor (TGF)-β1, but also reduced the apoptotic rate of the A549 cells and altered the expression of apoptosis-associated proteins (Bcl-2 and caspase-3). Furthermore, CCN3 knockdown greatly inhibited the activation of nuclear factor (NF)-κB p65 in the A549 cells, and TGF-β/p-Smad and NF-κB inhibitors significantly decreased the expression level of CCN3 in A549 cells. In conclusion, our data indicate that CCN3 knockdown affects the expression of downstream genes through the TGF-β/p-Smad or NF-κB pathways, leading to the inhibition of cell inflammation and apoptosis in human alveolar epithelial cells.

Correlation between serum transforming growth factor β1, interleukin-6 and neonatal respiratory distress syndrome

Trend and correlation of transforming growth factor β1 (TGF-β1) and interleukin-6 (IL-6) in serum of children with neonatal respiratory distress syndrome (NRDS) were investigated. A total of 75 NRDS children born in the Xiangyang Central Hospital from July 2015 to August 2017 were analyzed retrospectively. A total of 45 NRDS premature infants who received pulmonary surfactant (PS) within 12 h after birth were treated as PS group, 30 who did not receive PS treatment as non-PS group, and 32 premature infants without NRDS in the same period were selected as control group. Serum levels of TGF-β1 and IL-6 were detected by enzyme linked immunosorbent assay (ELISA) at various time points after birth and their correlation was analyzed. The expression level of TGF-β1 in serum of children in PS group was significantly higher than that in control group on days 1 and 3 after birth (P<0.05). The expression level of TGF-β1 in non-PS group increased continuously with the increase of number of days and was significantly higher than that in control group on days 1, 3 and 7 after birth (P<0.05), and significantly higher than that in PS group on days 3 and 7 after birth (P<0.05). The analysis of the correlation between the severity of the disease and the expression levels of TGF-β1 and IL-6 showed that the expression levels were elevated with the increase of the disease severity. The expression levels of TGF-β1 and IL-6 were positively correlated with severity of the disease (r=0.7509, P<0.05; r=0.8056, P<0.05). The expression levels of TGF-β1 and IL-6 in PS and non-PS groups were positively correlated (r=0.9042, P<0.05; r=0.8905, P<0.05). The results showed that serum TGF-β1 and IL-6 were elevated in NRDS children, and there was a positive correlation between them.

Transforming Growth Factor-β1 in predicting early lung fibroproliferation in patients with acute respiratory distress syndrome

Background

Fibroproliferative repair phase of the acute respiratory distress syndrome (ARDS) is followed by a restitutio ad integrum of lung parenchyma or by an irreversible lung fibrosis and patients’ death. Transforming Growth Factor-β1 (TGF-β1) is involved in collagen production and lung repair. We investigated whether alveolar TGF-β1 was associated with the presence of fibroproliferation and the outcome of ARDS patients.

Methods

Sixty-two patients were included the first day of moderate-to-severe ARDS. Bronchoalveolar lavage fluid (BALF) was collected at day 3 (and day 7 when the patients were still receiving invasive mechanical ventilation) from the onset of ARDS. Survival was evaluated at day 60. TGF-β1 was measured by immunoassay. The patients were classified as having lung fibroproliferation when the alveolar N-terminal peptide for type III procollagen (NT-PCP-III) measured on day 3 was > 9 μg/L as recently reported. The main objective of this study was to compare the alveolar levels of total TGF-β1 according to the presence or not a lung fibroproliferation at day 3.

Results

Forty-three patients (30.6%) presented a fibroproliferation at day 3. BALF levels of total TGF-β1 were not statistically different at day 3 (and at day 7) according to the presence or not lung fibroproliferation. Mortality at day 60 was higher in the group of patients with fibroproliferation as compared with patients with no fibroproliferation (68.4% vs. 18.6% respectively; p < 0.001). Total TGF-β1 measured on BALF at day 3 was not associated with the outcome. Multiple logistic regression showed that the presence of lung fibroproliferation was associated with death. In contrast, TGF-β1 was not independently associated with death.

Conclusions

Pulmonary levels of TGF-β1 during the first week of ARDS were not associated nor with the presence of fibroproliferation neither with death. TGF-β1 should not be used as a biomarker to direct anti-fibrotic therapies.

TGF-β1 Suppresses the Type I IFN Response and Induces Mitochondrial Dysfunction in Alveolar Macrophages

TGF-β1 is a pleiotropic cytokine with an established role in fibrosis; however, the immunosuppressive effects of TGF-β1 are less characterized. Elevated levels of TGF-β1 are found in patients with acute and chronic lung diseases, and the underlying disease processes are exacerbated by respiratory viral infections. The alveolar macrophage is the first line of cellular defense against respiratory viral infections, and its response to infections is dependent on environmental cues. Using the mouse alveolar macrophage line, MH-S, and human CD14⁺ monocyte-derived macrophages, we examined the effects of TGF-β1 on the type I IFN antiviral response, macrophage polarization, and mitochondrial bioenergetics following a challenge with human respiratory syncytial virus (RSV). Our results showed that TGF-β1 treatment of macrophages decreased the antiviral and proinflammatory response, and suppressed basal, maximal, spare mitochondrial respiration, and mitochondrial ATP production. Challenge with RSV following TGF-β1 treatment further exacerbated mitochondrial dysfunction. The TGF-β1 and TGF-β1+RSV-treated macrophages had a higher frequency of apoptosis and diminished phagocytic capacity, potentially through mitochondrial stress. Disruption of TGF-β1 signaling or rescue of mitochondrial respiration may be novel therapeutically targetable pathways to improve macrophage function and prevent secondary bacterial infections that complicate viral respiratory infections.

Pine bark extract (Pycnogenol®) suppresses cigarette smoke-induced fibrotic response via transforming growth factor-β1/Smad family member 2/3 signaling

Chronic obstructive pulmonary diseases (COPD) is an important disease featured as intense inflammation, protease imbalance, and air flow limitation and mainly induced by cigarette smoke (CS). In present study, we explored the effects of Pycnogenol® (PYC, pine bark extract) on pulmonary fibrosis caused by CS+lipopolysaccharide (LPS) exposure. Mice were treated with LPS intranasally on day 12 and 26, followed by CS exposure for 1 h/day (8 cigarettes per day) for 4 weeks. One hour before CS exposure, 10 and 20 mg/kg of PYC were administered by oral gavage for 4 weeks. PYC effectively reduced the number of inflammatory cells and proinflammatory mediators caused by CS+LPS exposure in bronchoalveolar lavage fluid. PYC inhibited the collagen deposition on lung tissue caused by CS+LPS exposure, as evidenced by Masson's trichrome stain. Furthermore, transforming growth factor-β1 (TGF-β1) expression and Smad family member 2/3 (Smad 2/3) phosphorylation were effectively suppressed by PYC treatment. PYC markedly reduced the collagen deposition caused by CS+LPS exposure, which was closely involved in TGF-β1/Smad 2/3 signaling, which is associated with pulmonary fibrotic change. These findings suggest that treatment with PYC could be a therapeutic strategy for controlling COPD progression.

The Role of Matrix Metalloproteinases in Development, Repair, and Destruction of the Lungs

Normal gas exchange after birth requires functional lung alveolar units that are lined with epithelial cells, parts of which are intricately fused with microvascular capillaries. A significant phase of alveolar lung development occurs in the perinatal period, continues throughout early stages in life, and requires activation of matrix-remodeling enzymes. Failure to achieve an optimum number of alveoli during lung maturation can cause several untoward medical consequences including disabling obstructive and/or restrictive lung diseases that limit physiological endurance and increase mortality. Several members of the matrix metalloproteinase (MMP) family are critical in lung remodeling before and after birth; however, their resurgence in response to environmental factors, infection, and injury can also compromise lung function. Therefore, temporal expression, regulation, and function of MMPs play key roles in developing and maintaining adequate oxygenation under steady state, as well as in diseased conditions. Broadly, with the exception of MMP2 and MMP14, most deletional mutations of MMPs fail to perturb lung development; however, their individual absence can alter the pathophysiology of respiratory diseases. Specifically, under stressed conditions such as acute respiratory infection and allergic inflammation, MMP2 and MMP9 can play a protective role through bacterial clearance and production of chemotactic gradient, while loss of MMP12 can protect mice from smoke-induced lung disease. Therefore, better understanding of the expression and function of MMPs under normal lung development and their resurgence in response respiratory diseases could provide new therapeutic options in the future.

Inhibition of c-Jun N-terminal Kinase Signaling Pathway Alleviates Lipopolysaccharide-induced Acute Respiratory Distress Syndrome in Rats

Background:

An acute respiratory distress syndrome (ARDS) is still one of the major challenges in critically ill patients. This study aimed to investigate the effect of inhibiting c-Jun N-terminal kinase (JNK) on ARDS in a lipopolysaccharide (LPS)-induced ARDS rat model.

Methods:

Thirty-six rats were randomized into three groups: control, LPS, and LPS + JNK inhibitor. Rats were sacrificed 8 h after LPS treatment. The lung edema was observed by measuring the wet-to-dry weight (W/D) ratio of the lung. The severity of pulmonary inflammation was observed by measuring myeloperoxidase (MPO) activity of lung tissue. Moreover, the neutrophils in bronchoalveolar lavage fluid (BALF) were counted to observe the airway inflammation. In addition, lung collagen accumulation was quantified by Sircol Collagen Assay. At the same time, the pulmonary histologic examination was performed, and lung injury score was achieved in all three groups.

Results:

MPO activity in lung tissue was found increased in rats treated with LPS comparing with that in control (1.26 ± 0.15 U in LPS vs. 0.77 ± 0.27 U in control, P < 0.05). Inhibiting JNK attenuated LPS-induced MPO activity upregulation (0.52 ± 0.12 U in LPS + JNK inhibitor vs. 1.26 ± 0.15 U in LPS, P < 0.05). Neutrophils in BALF were also found to be increased with LPS treatment, and inhibiting JNK attenuated LPS-induced neutrophils increase in BALF (255.0 ± 164.4 in LPS vs. 53 (44.5-103) in control vs. 127.0 ± 44.3 in LPS + JNK inhibitor, P < 0.05). At the same time, the lung injury score showed a reduction in LPS + JNK inhibitor group comparing with that in LPS group (13.42 ± 4.82 vs. 7.00 ± 1.83, P = 0.001). However, the lung W/D ratio and the collagen in BALF did not show any differences between LPS and LPS + JNK inhibitor group.

Conclusions:

Inhibiting JNK alleviated LPS-induced acute lung inflammation and had no effects on pulmonary edema and fibrosis. JNK inhibitor might be a potential therapeutic medication in ARDS, in the context of reducing lung inflammatory.

The Role of TGF-β in the Association Between Primary Graft Dysfunction and Bronchiolitis Obliterans Syndrome

Primary graft dysfunction (PGD) is a possible risk factor for bronchiolitis obliterans syndrome (BOS) following lung transplantation; however, the mechanism for any such association is poorly understood. Based on the association of TGF-β with acute and chronic inflammatory disorders, we hypothesized that it might play a role in the continuum between PGD and BOS. Thus, the association between PGD and BOS was assessed in a single-center cohort of lung transplant recipients. Bronchoalveolar lavage fluid concentrations of TGF-β and procollagen collected within 24 h of transplantation were compared across the spectrum of PGD, and incorporated into Cox models of BOS. Immunohistochemistry localized expression of TGF-β and its receptor in early lung biopsies posttransplant. We found an association between PGD and BOS in both bilateral and single lung recipients with a hazard ratio of 3.07 (95% CI 1.76-5.38) for the most severe form of PGD. TGF-β and procollagen concentrations were elevated during PGD (p < 0.01), and associated with increased rates of BOS. Expression of TGF-β and its receptor localized to allograft infiltrating mononuclear and stromal cells, and the airway epithelium. These findings validate the association between PGD and the subsequent development of BOS, and suggest that this association may be mediated by receptor/TGF-β biology.

The effect of positive end-expiratory pressure on inflammatory cytokines during laparoscopic cholecystectomy

Objectives:

To investigate effects of the positive end-expiratory pressure (PEEP) application of 10 cm H₂O on the plasma levels of cytokines during laparoscopic cholecystectomy.

Methods:

A prospective study was conducted on 40 patients who presented to the Department of General Surgery, Medical Faculty, Turgut Özal University, Ankara, Turkey scheduled for laparoscopic cholecystectomy operation during a 10 month period from September 2012 to June 2013. Forty patients scheduled for laparoscopic cholecystectomy operation were randomly divided into 2 groups; ventilation through zero end-expiratory pressure (ZEEP) (0 cm H₂O PEEP) (n=20), and PEEP (10 cm H₂O PEEP) (n=20). All patients were ventilated with 8 ml/kg TV. Levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL 10, and transforming growth factor (TGF)-β1 were measured in the pre- and post-operatively collected samples.

Results:

Blood samples of 30 patients’ were analyzed for plasma cytokine levels, and 10 were excluded from the study due to hemolysis. Post-operative plasma IL-6 levels were observed to be significantly higher than the pre-operative patients (p=0.035). Post-operative plasma TGF-β1 levels in the PEEP group was found significantly higher compared with the pre-operative group levels (p=0.033). However, there were no significant differences in the pre- and post-operative plasma cytokine levels between the 2 groups.

Conclusion:

The application of PEEP of 10 cm H₂O, which has known beneficial effect on respiratory mechanics, does not have any effect on systemic inflammatory response undergoing pneumoperitoneum during laparoscopic cholecystectomy surgery.

Therapeutic effects of bone marrow-derived mesenchymal stem cells on radiation-induced lung injury

Radiation-induced lung injury (RILI) is a fatal condition featured by interstitial pneumonitis and fibrosis. Mesenchymal stem cells (MSCs) have been widely used for treating RILI in rodent models. In the present study, we aimed to investigate whether the therapeutic effects of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) on RILI were in a dose-dependent manner. A total of 100 mice were randomly divided into: a control group (n=25), subject to lung irradiation and injection of phosphate-buffered solution (PBS) via the tail vein; and the hBM-MSC group, subject to lung irradiation followed by injection of a low dose (1x103 hBM-MSCs/g), medium dose (5x103 hBM-MSCs/g) and high dose (1x104 hBM-MSCs/g) of hBM-MSCs in PBS through the tail vein, respectively. After sacrifice, the pulmonary tissues were subject to hematoxylin and eosin (H&E) staining, Masson's trichrome staining and immunohistochemical staining to investigate the pathological changes. Immunofluorescent staining was performed to evaluate the differentiation capacity of hBM-MSCs in vivo by analyzing the expression of SPC and PECAM. hBM-MSCs improved the survival rate and histopathological features in the irradiated mice, especially in the low-dose group. Marked decrease in collagen deposition was noted in the irradiated mice treated using a low dose of hBM-MSCs. In addition, hBM-MSCs attenuated secretion and expression of IL-10 and increased the expression of TNF-α. Furthermore, hBM-MSCs had the potential to differentiate into functional cells upon lung injury. Low-dose hBM-MSCs contributed to functional recovery in mice with RILI.

Hirsutella sinensis mycelium attenuates bleomycin-induced pulmonary inflammation and fibrosis in vivo

Hirsutella sinensis mycelium (HSM), the anamorph of Cordyceps sinensis, is a traditional Chinese medicine that has been shown to possess various pharmacological properties. We previously reported that this fungus suppresses interleukin-1β and IL-18 secretion by inhibiting both canonical and non-canonical inflammasomes in human macrophages. However, whether HSM may be used to prevent lung fibrosis and the mechanism underlying this activity remain unclear. Our results show that pretreatment with HSM inhibits TGF-β1–induced expression of fibronectin and α-SMA in lung fibroblasts. HSM also restores superoxide dismutase expression in TGF-β1–treated lung fibroblasts and inhibits reactive oxygen species production in lung epithelial cells. Furthermore, HSM pretreatment markedly reduces bleomycin–induced lung injury and fibrosis in mice. Accordingly, HSM reduces inflammatory cell accumulation in bronchoalveolar lavage fluid and proinflammatory cytokines levels in lung tissues. The HSM extract also significantly reduces TGF-β1 in lung tissues, and this effect is accompanied by decreased collagen 3α1 and α-SMA levels. Moreover, HSM reduces expression of the NLRP3 inflammasome and P2X₇R in lung tissues, whereas it enhances expression of superoxide dismutase. These findings suggest that HSM may be used for the treatment of pulmonary inflammation and fibrosis.

Paraquat induce pulmonary epithelial-mesenchymal transition through transforming growth factor-β1-dependent mechanism

Pulmonary fibrosis is prevalent in Paraquat (PQ) poisoning. Transforming growth factor β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) of Type II alveolar epithelial cells (AT2) contributed to the pulmonary fibrosis in some pulmonary disease. In this study, we investigated whether PQ could induce EMT in AT2 through transforming growth factor β1 (TGF-β1) signal pathway in vitro. Morphological and phenotypic characterizations were evaluated on AT2 cell lines A549 cells in the presence of PQ with or without TGF-β1 inhibitors SB431542 for 5 days. As a result, PQ induced the transition of A549 cells from epithelial morphology to fibroblast-like morphology, associated with the acquisition of migratory properties. Phenotypically, PQ induced-EMT was characterized by loss of epithelial cell markers including E-cadherin and zonula occludens (ZO-1), while up-expressions of mesenchymal cell markers including α-smooth muscle actin (α-SMA) and vimentin, concurrent with increased type I collagen (Col I). SB431542 suppressed PQ-induced EMT via inhibiting expressions of phospho-Smad2 and phospho-Smad3. These findings conclusively demonstrated that the cultured A549 cells underwent EMT in the presence of PQ, and suggested that TGF-β1 played a central role in PQ-induced EMT.

Early initiation of continuous renal replacement therapy improves clinical outcomes in patients with acute respiratory distress syndrome

BACKGROUND

The acute respiratory distress syndrome (ARDS) is a common devastating syndrome in intensive care unit in critically ill patients. Continuous renal replacement therapy (CRRT) has been shown beneficial effects on oxygenation and survival in patients with ARDS. However, it is still controversial about the timing of initiation of CRRT.

METHODS

Fifty-three patients with ARDS admitted to intensive care unit in Zhejiang Provincial People's Hospital, China from 2009 to 2013 were enrolled in the study. The authors compared ventilation parameter, including PaO2/FIO2, A-a gradient, positive end-expiratory pressure, plateau pressure, dynamic compliance and hemodynamic parameters, including central venous pressure, mean arterial pressure, cardiac index, extravascular lung water index, fluid balance between early initiation (within 12 hours after ARDS onset) and late initiation of CRRT (48 hours after ARDS onset) groups. The authors further investigated transforming growth factor (TGF)-β1 level changes in serum and bronchoalveolar lavage fluid (BALF) by enzyme-linked immunosorbent assay during 7 days of follow-up.

RESULTS

Significant improvement of oxygenation and shorter duration of mechanical ventilation were observed in early CRRT group during 7-day follow-up. In addition, TGF-β1 concentrations in serum and BALF were significantly decreased in patients with early initiation of CRRT compared to those with late initiation of CRRT on day 2 and day 7. Furthermore, patients who died of ARDS had higher levels of TGF-β1 in BALF than survivors.

CONCLUSIONS

Our findings showed that early initiation of CRRT is associated with favorable clinical outcomes in ARDS patients, which might be due to the reduced serum and BALF TGF-β1 levels through CRRT. However, large multi-center studies are needed to make further recommendations as to the optimal use of CRRT in ARDS patient populations.

Molecular activation of the NLRP3 Inflammasome in fibrosis: common threads linking divergent fibrogenic diseases

SIGNIFICANCE

Over the past 10 years, there has been a plethora of investigations centering on the NLRP3 inflammasome and its role in fibrosis and other disease pathologies. To date, the signaling pathways from the inflammasome to myofibroblast differentiation and chronic collagen synthesis have not been fully elucidated, and many questions are left to be answered.

RECENT ADVANCES

Recent studies have demonstrated the significant and critical role of reactive oxygen species (ROS) and calcium signaling in the assembly of the inflammasome, and this may result in autocrine signaling maintaining the myofibroblast phenotype, leading to fibrotic disease.

CRITICAL ISSUES

Traditionally, myofibroblasts under tight regulation aid in wound healing and then, once the wound has closed, undergo apoptosis and the collagen in the wound remodels. During fibrosis, however, the myofibroblast maintains an activated state via a chronically activated inflammasome, leading to the continual synthesis of collagens and other extracellular matrix proteins that result in damage to the tissue or organ. The mechanism that is driving this abnormality has not been fully elucidated.

FUTURE DIRECTIONS

However, studies have been conducted to suggest that modulating the calcium or the ROS axis may be of therapeutic value in regulating inflammasome activation. A number of novel drugs are currently being developed that may prove beneficial to patients suffering from fibrotic diseases.

Matrix metalloproteinases and protein tyrosine kinases: potential novel targets in acute lung injury and ARDS

Acute lung injury (ALI) and ARDS fall within a spectrum of pulmonary disease that is characterized by hypoxemia, noncardiogenic pulmonary edema, and dysregulated and excessive inflammation. While mortality rates have improved with the advent of specialized ICUs and lung protective mechanical ventilation strategies, few other therapies have proven effective in the management of ARDS, which remains a significant clinical problem. Further development of biomarkers of disease severity, response to therapy, and prognosis is urgently needed. Several novel pathways have been identified and studied with respect to the pathogenesis of ALI and ARDS that show promise in bridging some of these gaps. This review will focus on the roles of matrix metalloproteinases and protein tyrosine kinases in the pathobiology of ALI in humans, and in animal models and in vitro studies. These molecules can act independently, as well as coordinately, in a feed-forward manner via activation of tyrosine kinase-regulated pathways that are pivotal in the development of ARDS. Specific signaling events involving proteolytic processing by matrix metalloproteinases that contribute to ALI, including cytokine and chemokine activation and release, neutrophil recruitment, transmigration and activation, and disruption of the intact alveolar-capillary barrier, will be explored in the context of these novel molecular pathways.

Pulmonary microRNA expression profiling in an immature piglet model of cardiopulmonary bypass-induced acute lung injury

After surgery performed under cardiopulmonary bypass (CPB), severe lung injury often occurs in infants. MicroRNAs (miRNAs) are potentially involved in diverse pathophysiological processes via regulation of gene expression. The objective of this study was to investigate differentially expressed miRNAs and their potential target genes in immature piglet lungs in response to CPB. Fourteen piglets aged 18.6 ± 0.5 days were equally divided into two groups that underwent sham sternotomy or CPB. The duration of aortic cross-clamping was 2 h, followed by 2 h reperfusion. Lung injury was evaluated by lung function indices, levels of cytokines, and histological changes. We applied miRNA microarray and quantitative real-time polymerase chain reaction (qRT-PCR) analysis to determine miRNA expression. Meanwhile, qRT-PCR and enzyme-linked immunosorbent assay were used for validation of predicted mRNA targets. The deterioration of lung function and histopathological changes revealed the piglets' lungs were greatly impaired due to CPB. The levels of tumor necrosis factor alpha, interleukin 6, and interleukin 10 increased in the lung tissue after CPB. Using miRNA microarray, statistically significant differences were found in the levels of 16 miRNAs in the CPB group. Up-regulation of miR-21 was verified by PCR. We also observed down-regulation in the levels of miR-127, miR-145, and miR-204, which were correlated with increases in the expression of the products of their potential target genes PIK3CG, PTGS2, ACE, and IL6R in the CPB group, suggesting a potential role for miRNA in the regulation of inflammatory response. Our results show that CPB induces severe lung injury and dynamic changes in miRNA expression in piglet lungs. Moreover, the changes in miRNA levels and target gene expression may provide a basis for understanding the pathogenesis of CPB-induced injury to immature lungs.

Mechanical ventilation-associated lung fibrosis in acute respiratory distress syndrome: a significant contributor to poor outcome

One of the most challenging problems in critical care medicine is the management of patients with the acute respiratory distress syndrome. Increasing evidence from experimental and clinical studies suggests that mechanical ventilation, which is necessary for life support in patients with acute respiratory distress syndrome, can cause lung fibrosis, which may significantly contribute to morbidity and mortality. The role of mechanical stress as an inciting factor for lung fibrosis versus its role in lung homeostasis and the restoration of normal pulmonary parenchymal architecture is poorly understood. In this review, the authors explore recent advances in the field of pulmonary fibrosis in the context of acute respiratory distress syndrome, concentrating on its relevance to the practice of mechanical ventilation, as commonly applied by anesthetists and intensivists. The authors focus the discussion on the thesis that mechanical ventilation-or more specifically, that ventilator-induced lung injury-may be a major contributor to lung fibrosis. The authors critically appraise possible mechanisms underlying the mechanical stress-induced lung fibrosis and highlight potential therapeutic strategies to mitigate this fibrosis.

Protein-based therapies for acute lung injury: targeting neutrophil extracellular traps

INTRODUCTION

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are the acute onset of noncardiac respiratory insufficiency associated with bilateral lung infiltrations. During the past decade, mechanical ventilation strategies using low tidal volumes have reduced the mortality of ALI/ARDS to ∼ 20 - 40%. However, ALI/ARDS continues to be a major factor in global burden of diseases, with no pharmacological agents currently available.

AREAS COVERED

In this review, we discuss several inflammatory proteins involved in the molecular pathogenesis of ALI/ARDS. The complement cleavage product, C5a, is a peptide acting as a potent anaphylatoxin. C5a may trigger the formation of neutrophil extracellular traps (NETs) and release of histone proteins to the extracellular compartment during ALI/ARDS. NETs may activate platelets to release TGF-β, which is involved in tissue remodeling during the later phases of ALI/ARDS. Interception of C5a signaling or blockade of extracellular histones has recently shown promising beneficial effects in small animal models of ALI/ARDS.

EXPERT OPINION

Novel protein-based strategies for the treatment of ALI/ARDS may inspire the hopes of scientists, clinicians, and patients. Although neutralization of extracellular histones/NETs, C5a, and TGF-β is effective in experimental models of ALI/ARDS, controlled clinical trials will be necessary for further evaluation in future.

Early activation of pulmonary TGF-β1/Smad2 signaling in mice with acute pancreatitis-associated acute lung injury

Acute lung injury is caused by many factors including acute pancreatitis. There is no specific therapy directed at underlying pathophysiological mechanisms for acute lung injury. Transforming growth factor-β (TGF-β) is involved in the resolution of lung injury in later phases of the disease. Some evidence exists demonstrating that TGF-β not only is involved in the late stages, but also contributes to lung injury early on in the progress of the disease. Acute pancreatitis was induced using ductal ligation in mice. TGF-β1, 2, and 3, TβRII, ALK-5, Smad2, 3, 4, and 7, and P-Smad2 expression in the lungs were analyzed at 9 and 24 h. We demonstrate that TGF- β1 levels in the lungs of mice with acute pancreatitis increase as early as 9 h after induction. We observed an increased expression of ALK-5 in acute pancreatitis at both 9 and 24 h. Inhibitory Smad7 expression was transiently increased at 9 h in acute pancreatitis, but reduced later at 24 h, with a concomitant increased nuclear translocation of phosphorylated Smad2. Our findings demonstrate activation of TGF-β signaling in the lungs as early as 24 h after acute pancreatitis, suggesting that TGF-β may represent a potential therapeutic candidate in acute pancreatitis-induced acute lung injury.

Intersectin-1s: an important regulator of cellular and molecular pathways in lung injury

Abstract Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe syndromes resulting from the diffuse damage of the pulmonary parenchyma. ALI and ARDS are induced by a plethora of local or systemic insults, leading to the activation of multiple pathways responsible for injury, resolution, and repair or scarring of the lungs. Despite the large efforts aimed at exploring the roles of different pathways in humans and animal models and the great strides made in understanding the pathogenesis of ALI/ARDS, the only viable treatment options are still dependent on ventilator and cardiovascular support. Investigation of the pathophysiological mechanisms responsible for initiation and resolution or advancement toward lung scarring in ALI/ARDS animal models led to a better understanding of the disease's complexity and helped in elucidating the links between ALI and systemic multiorgan failure. Although animal models of ALI/ARDS have pointed out a variety of new ideas for study, there are still limited data regarding the initiating factors, the critical steps in the progression of the disease, and the central mechanisms dictating its resolution or progression to lung scarring. Recent studies link deficiency of intersectin-1s (ITSN-1s), a prosurvival protein of lung endothelial cells, to endothelial barrier dysfunction and pulmonary edema as well as to the repair/recovery from ALI. This review discusses the effects of ITSN-1s deficiency on pulmonary endothelium and its significance in the pathology of ALI/ARDS.

Curcumin modulates the inflammatory response and inhibits subsequent fibrosis in a mouse model of viral-induced acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) is a clinical syndrome characterized by diffuse alveolar damage usually secondary to an intense host inflammatory response of the lung to a pulmonary or extrapulmonary infectious or non-infectious insult often leading to the development of intra-alveolar and interstitial fibrosis. Curcumin, the principal curcumoid of the popular Indian spice turmeric, has been demonstrated as an anti-oxidant and anti-inflammatory agent in a broad spectrum of diseases. Using our well-established model of reovirus 1/L-induced acute viral pneumonia, which displays many of the characteristics of the human ALI/ARDS, we evaluated the anti-inflammatory and anti-fibrotic effects of curcumin. Female CBA/J mice were treated with curcumin (50 mg/kg) 5 days prior to intranasal inoculation with 10(7)pfu reovirus 1/L and daily, thereafter. Mice were evaluated for key features associated with ALI/ARDS. Administration of curcumin significantly modulated inflammation and fibrosis, as revealed by histological and biochemical analysis. The expression of IL-6, IL-10, IFNγ, and MCP-1, key chemokines/cytokines implicated in the development of ALI/ARDS, from both the inflammatory infiltrate and whole lung tissue were modulated by curcumin potentially through a reduction in the phosphorylated form of NFκB p65. While the expression of TGFß1 was not modulated by curcumin, TGFß Receptor II, which is required for TGFß signaling, was significantly reduced. In addition, curcumin also significantly inhibited the expression of α-smooth muscle actin and Tenascin-C, key markers of myofibroblast activation. This data strongly supports a role for curcumin in modulating the pathogenesis of viral-induced ALI/ARDS in a pre-clinical model potentially manifested through the alteration of inflammation and myofibroblast differentiation.

Pulmonary microRNA profiling in a mouse model of ventilator-induced lung injury

The aim of this study was to investigate the changes induced by high tidal volume ventilation (HVTV) in pulmonary expression of micro-RNAs (miRNAs) and identify potential target genes and corresponding miRNA-gene networks. Using a real-time RT-PCR-based array in RNA samples from lungs of mice subjected to HVTV for 1 or 4 h and control mice, we identified 65 miRNAs whose expression changed more than twofold upon HVTV. An inflammatory and a TGF-β-signaling miRNA-gene network were identified by in silico pathway analysis being at highest statistical significance (P = 10(-43) and P = 10(-28), respectively). In the inflammatory network, IL-6 and SOCS-1, regulated by miRNAs let-7 and miR-155, respectively, appeared as central nodes. In TGF-β-signaling network, SMAD-4, regulated by miR-146, appeared as a central node. The contribution of miRNAs to the development of lung injury was evaluated in mice subjected to HVTV treated with a precursor or antagonist of miR-21, a miRNA highly upregulated by HVTV. Lung compliance was preserved only in mice treated with anti-miR-21 but not in mice treated with pre-miR-21 or negative-control miRNA. Both alveolar-arterial oxygen difference and protein levels in bronchoalveolar lavage were lower in mice treated with anti-miR-21 than in mice treated with pre-miR-21 or negative-control miRNA (D(A-a): 66 ± 27 vs. 131 ± 22, 144 ± 10 mmHg, respectively, P < 0.001; protein concentration: 1.1 ± 0.2 vs. 2.3 ± 1, 2.1 ± 0.4 mg/ml, respectively, P < 0.01). Our results show that HVTV induces changes in miRNA expression in mouse lungs. Modulation of miRNA expression can affect the development of HVTV-induced lung injury.

Sepsis-induced acute respiratory distress syndrome with fatal outcome is associated to increased serum transforming growth factor beta-1 levels

BACKGROUND

TGF-β1 is a promoter of pulmonary fibrosis in many chronic inflammatory diseases. TGF-β1 circulating levels in patients with sepsis-induced Acute Respiratory Distress Syndrome (ARDS) have not been established.

METHODS

In this prospective pilot cohort study, serum bioactive TGF-β1 concentration, determined by sandwich ELISA, was analyzed in 52 patients who fulfilled criteria for septic shock at admission and on days 3 and 7.

RESULTS

Of the 52 patients enrolled in the study, 46.1% fulfilled the criteria for ARDS on admission. At ICU admission, there were not statistical differences in TGF-β1 concentrations between septic shock patients with or without ARDS. After 7 days of follow-up in ICU, circulating TGF-β1 levels were significantly higher in patients with sepsis and ARDS than in those without ARDS [55.47 (35.04-79.48 pg/ml) versus 31.65 (22.89-45.63 pg/ml), respectively] (p = 0.002). Furthermore, in septic shock associated ARDS patients, TGF-β1 levels were significantly higher in nonsurvivors than in survivors [85.23 (78.19-96.30 pg/ml) versus 36.41 (30.21-55.47 pg/ml), respectively] (p = 0.006) on day 7 of ICU follow-up.

CONCLUSIONS

In patients with septic shock, persistent ARDS is accompanied with increased circulating TGF-β1 levels. Furthermore, ARDS patients with fatal outcome show higher TGF-β1 concentrations than survivors. These results suggest the relevance of TGF-β1 levels found in the pathogenesis of persistent sepsis-induced ARDS.

Vimentin is sufficient and required for wound repair and remodeling in alveolar epithelial cells

The physiological and pathophysiological implications of the expression of vimentin, a type III intermediate filament protein, in alveolar epithelial cells (AECs) are unknown. We provide data demonstrating that vimentin is regulated by TGFβ1, a major cytokine released in response to acute lung injury and that vimentin is required for wound repair and remodeling of the alveolar epithelium. Quantitative real-time PCR shows a 16-fold induction of vimentin mRNA in TGFβ1-treated transformed AECs. Luciferase assays identify a Smad-binding element in the 5' promoter of vimentin responsible for TGFβ1-induced transcription. Notably, TGFβ1 induces vimentin protein expression in AECs, which is associated with a 2.5-fold increase in cell motility, resulting in increased rates of migration and wound closure. These effects are independent of cell proliferation. TGFβ1-mediated vimentin protein expression, cell migration, and wound closure are prevented by a pharmacological inhibitor of the Smad pathway and by expression of Ad-shRNA against vimentin. Conversely, overexpression of mEmerald-vimentin is sufficient for increased cell-migration and wound-closure rates. These results demonstrate that vimentin is required and sufficient for increased wound repair in an in vitro model of lung injury.

Influenza induces endoplasmic reticulum stress, caspase-12-dependent apoptosis, and c-Jun N-terminal kinase-mediated transforming growth factor-β release in lung epithelial cells

Influenza A virus (IAV) infection is known to induce endoplasmic reticulum (ER) stress, Fas-dependent apoptosis, and TGF-β production in a variety of cells. However, the relationship between these events in murine primary tracheal epithelial cells (MTECS), which are considered one of the primary sites of IAV infection and replication, is unclear. We show that IAV infection induced ER stress marker activating transcription factor-6 and endoplasmic reticulum protein 57-kD (ERp57), but not C/EBP homologous protein (CHOP). In contrast, the ER stress inducer thapsigargin (THP) increased CHOP. IAV infection activated caspases and apoptosis, independently of Fas and caspase-8, in MTECs. Instead, apoptosis was mediated by caspase-12. A decrease in ERp57 attenuated the IAV burden and decreased caspase-12 activation and apoptosis in epithelial cells. TGF-β production was enhanced in IAV-infected MTECs, compared with THP or staurosporine. IAV infection caused the activation of c-Jun N-terminal kinase (JNK). Furthermore, IAV-induced TGF-β production required the presence of JNK1, a finding that suggests a role for JNK1 in IAV-induced epithelial injury and subsequent TGF-β production. These novel findings suggest a potential mechanistic role for a distinct ER stress response induced by IAV, and a profibrogenic/repair response in contrast to other pharmacological inducers of ER stress. These responses may also have a potential role in acute lung injury, fibroproliferative acute respiratory distress syndrome, and the recently identified H1N1 influenza-induced exacerbations of chronic obstructive pulmonary disease (Wedzicha JA. Proc Am Thorac Soc 2004;1:115-120) and idiopathic pulmonary fibrosis (Umeda Y, et al. Int Med 2010;49:2333-2336).

Pulmonary microvascular endothelial cells from bleomycin-induced rats promote the transformation and collagen synthesis of fibroblasts

Accumulation and activation of myofibroblasts are the hallmark of progressive pulmonary fibrosis, and the resident fibroblasts are the major source of myofibroblasts. However, the key factors involved in the transformation of fibroblasts are unknown. Pulmonary microvascular endothelial cells (PMVECs), major effector cells against pathogenesis in early stages of the disease, can secrete cytokines to induce the differentiation of mesenchymal cells. We speculated that PMVECs could secrete pro-fibrotic cytokines and promote the transformation of fibroblasts into myofibroblasts. Accordingly, we established a co-culture system with PMVECs and fibroblasts to examine the specific transformation and collagen synthesis of the co-cultured fibroblasts by FACS and Western blot, prior to and after treatment with neutralizing antibodies against transforming growth factor-beta1 (TGF-β1) and connective tissue growth factor (CTGF). We also analyzed expression of TGF-β1 and CTGF in PMVECs. The synthesis and secretion of TGF-β1 and CTGF protein were up-regulated in PMVECs isolated from bleomycin (BLM)-treated rats, most prominently at 7 days post-instillation. We showed that the PMVECs isolated from BLM-induced rats could induce the transformation of normal fibroblasts and their secretion of collagen I, which was inhibited by both neutralizing anti-TGF-β1 and anti-CTGF antibodies. Therefore, up-regulation of TGF-β1 and CTGF in PMVECs plays an important role in activation, transformation, and collagen synthesis of fibroblasts; in particular, these effects in PMVECs are likely to be the key factors for activation and stimulation of static fibroblasts in lung interstitium in early stages of pulmonary fibrosis disease.

Effect of nilotinib on bleomycin-induced acute lung injury and pulmonary fibrosis in mice

BACKGROUND

The tyrosine kinase inhibitor imatinib mesylate was developed as an inhibitor of the kinase activity of BCR-ABL. However, imatinib also has potent inhibitory activity against the platelet-derived growth factor receptor (PDGFR). Nilotinib is approved for treating patients with chronic myeloid leukemia showing resistance or intolerance to imatinib. Like imatinib, nilotinib selectively inhibits the tyrosine kinase activity of PDGFR.

OBJECTIVES

We examined the effect of imatinib and nilotinib on acute lung injury and pulmonary fibrosis in a mouse model.

METHODS

Mice were treated by intratracheal instillation of bleomycin. Imatinib or nilotinib were administered by oral gavage. To study the early inflammatory and late fibrotic phases of lung injury, mice were sacrificed on days 3, 7, 14 and 21 after bleomycin instillation.

RESULTS

Histopathology showed that imatinib and nilotinib attenuated the extent of lung injury and fibrosis. The numbers of inflammatory cells and levels of IL-6, IL-1β and tumor necrosis factor-α were decreased in the imatinib and nilotinib groups on days 3 and 7. Imatinib and nilotinib therapy significantly reduced the levels of hydroxyproline on days 14 and 21, which was accompanied by decreased expression levels of transforming growth factor (TGF)-β1 and PDGFR-β. Imatinib and nilotinib also significantly reduced the expression levels of the genes for TGF-β1 and platelet-derived growth factor (PDGF). Imatinib and nilotinib treatment also significantly inhibited the PDGF-induced proliferation of lung fibroblasts in vitro. When imatinib or nilotinib was given 7 days after the instillation of bleomycin, only nilotinib attenuated pulmonary fibrosis.

CONCLUSIONS

Imatinib and nilotinib attenuated bleomycin-induced acute lung injury and pulmonary fibrosis in mice. In a therapeutic model, nilotinib showed more potent antifibrotic effects than imatinib.

Haplotype association mapping of acute lung injury in mice implicates activin a receptor, type 1

RATIONALE

Because acute lung injury is a sporadic disease produced by heterogeneous precipitating factors, previous genetic analyses are mainly limited to candidate gene case-control studies.

OBJECTIVES

To develop a genome-wide strategy in which single nucleotide polymorphism associations are assessed for functional consequences to survival during acute lung injury in mice.

METHODS

To identify genes associated with acute lung injury, 40 inbred strains were exposed to acrolein and haplotype association mapping, microarray, and DNA-protein binding were assessed.

MEASUREMENTS AND MAIN RESULTS

The mean survival time varied among mouse strains with polar strains differing approximately 2.5-fold. Associations were identified on chromosomes 1, 2, 4, 11, and 12. Seven genes (Acvr1, Cacnb4, Ccdc148, Galnt13, Rfwd2, Rpap2, and Tgfbr3) had single nucleotide polymorphism (SNP) associations within the gene. Because SNP associations may encompass "blocks" of associated variants, functional assessment was performed in 91 genes within ± 1 Mbp of each SNP association. Using 10% or greater allelic frequency and 10% or greater phenotype explained as threshold criteria, 16 genes were assessed by microarray and reverse real-time polymerase chain reaction. Microarray revealed several enriched pathways including transforming growth factor-β signaling. Transcripts for Acvr1, Arhgap15, Cacybp, Rfwd2, and Tgfbr3 differed between the strains with exposure and contained SNPs that could eliminate putative transcriptional factor recognition sites. Ccdc148, Fancl, and Tnn had sequence differences that could produce an amino acid substitution. Mycn and Mgat4a had a promoter SNP or 3'untranslated region SNPs, respectively. Several genes were related and encoded receptors (ACVR1, TGFBR3), transcription factors (MYCN, possibly CCDC148), and ubiquitin-proteasome (RFWD2, FANCL, CACYBP) proteins that can modulate cell signaling. An Acvr1 SNP eliminated a putative ELK1 binding site and diminished DNA-protein binding.

CONCLUSIONS

Assessment of genetic associations can be strengthened using a genetic/genomic approach. This approach identified several candidate genes, including Acvr1, associated with increased susceptibility to acute lung injury in mice.

Effect of methylprednisolone on perivascular pulmonary edema, inflammatory infiltrate, VEGF and TGF-beta immunoexpression in the remaining lungs of rats after left pneumonectomy

Pneumonectomy is associated with high rates of morbimortality, with postpneumonectomy pulmonary edema being one of the leading causes. An intrinsic inflammatory process following the operation has been considered in its physiopathology. The use of corticosteroids is related to prevention of this edema, but no experimental data are available to support this hypothesis. We evaluated the effect of methylprednisolone on the remaining lungs of rats submitted to left pneumonectomy concerning edema and inflammatory markers. Forty male Wistar rats weighing 300 g underwent left pneumonectomy and were randomized to receive corticosteroids or not. Methylprednisolone at a dose of 10 mg/kg was given before the surgery. After recovery, the animals were sacrificed at 48 and 72 h, when the pO(2)/FiO(2) ratio was determined. Right lung perivascular edema was measured by the index between perivascular and vascular area and neutrophil density by manual count. Tissue expression of vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-β) were evaluated by immunohistochemistry light microscopy. There was perivascular edema formation after 72 h in both groups (P = 0.0031). No difference was observed between operated animals that received corticosteroids and those that did not concerning the pO(2)/FiO(2) ratio, neutrophil density or TGF-β expression. The tissue expression of VEGF was elevated in the animals that received methylprednisolone both 48 and 72 h after surgery (P = 0.0243). Methylprednisolone was unable to enhance gas exchange and avoid an inflammatory infiltrate and TGF-β expression also showed that the inflammatory process was not correlated with pulmonary edema formation. However, the overexpression of VEGF in this group showed that methylprednisolone is related to this elevation.

Dual role of TGF-β1 on Fas-induced apoptosis in lung epithelial cells

Recent evidence suggests that TGF-β1 has a dual role in regulating cell response to Fas/Fas ligand (FasL)-induced apoptosis. TGF-β1 may play a positive or negative role on cell sensitivity to apoptosis via Fas/FasL system, depending on cell types and their specific environment. TGF-β1 and the Fas/FasL system are also involved in pathological processes of acute lung injury (ALI) and interstitial lung diseases including early lung injury and subsequent tissue repair. However, it is not well understood how TGF-β1 regulates Fas/FasL mediated apoptotic signaling in lung epithelium. In this study, we found that TGF-β1 could affect the sensitivity of lung epithelial A549 cells to Fas/FasL mediated apoptosis in a time-dependent manner. Apoptosis of A549 cells could be enhanced significantly by co-treatment with TGF-β1 and FasL, or pretreatment with TGF-β1 followed by FasL exposure, as evidenced by markedly increased caspase-8 and JNK activities. However, prolonged exposure to TGF-β1 could result in an obvious inhibition of the Fas/FasL-induced apoptosis, accompanied by down-regulation of Fas and up-regulation of c-Flip. Our results also showed that the effect of TGF-β1 on cell sensitivity to Fas-mediated apoptosis was independent of Akt pathway activation. These findings suggest that timely interplay of TGF-β1 and the Fas/FasL system could determine the final outcomes of cell survival/death signaling, for example, switching cell death signaling to survival signaling during early injury and later repair process of lung epithelium.

Integrating microRNAs into a system biology approach to acute lung injury

Acute lung injury (ALI), including the ventilator-induced lung injury (VILI) and the more severe acute respiratory distress syndrome (ARDS), are common and complex inflammatory lung diseases potentially affected by various genetic and nongenetic factors. Using the candidate gene approach, genetic variants associated with immune response and inflammatory pathways have been identified and implicated in ALI. Because gene expression is an intermediate phenotype that resides between the DNA sequence variation and the higher level cellular or whole-body phenotypes, the illustration of gene expression regulatory networks potentially could enhance understanding of disease susceptibility and the development of inflammatory lung syndromes. MicroRNAs (miRNAs) have emerged as a novel class of gene regulators that play critical roles in complex diseases including ALI. Comparisons of global miRNA profiles in animal models of ALI and VILI identified several miRNAs (eg, miR-146a and miR-155) previously implicated in immune response and inflammatory pathways. Therefore, via regulation of target genes in these biological processes and pathways, miRNAs potentially contribute to the development of ALI. Although this line of inquiry exists at a nascent stage, miRNAs have the potential to be critical components of a comprehensive model for inflammatory lung disease built by a systems biology approach that integrates genetic, genomic, proteomic, epigenetic as well as environmental stimuli information. Given their particularly recognized role in regulation of immune and inflammatory responses, miRNAs also serve as novel therapeutic targets and biomarkers for ALI/ARDS or VILI, thus facilitating the realization of personalized medicine for individuals with acute inflammatory lung disease.

Effect of pravastatin on bleomycin-induced acute lung injury and pulmonary fibrosis

1. Pravastatin is best known for its antilipidemic action. Recent studies have shown that statins have immunomodulatory and anti-inflammatory effects. The present study aimed to determine whether or not pravastatin can attenuate acute lung injury and fibrosis in a mouse model. 2. Bleomycin was given to C57BL6 mice through intratracheal instillation. Pravastatin was given through intraperitoneal injection. To study the effect of pravastatin on the early inflammatory phase and the late fibrotic phase, mice were killed on days 3, 7, 14 and 21. 3. Pravastatin attenuated the histopathological change of bleomycin-induced lung injury and fibrosis. The accumulation of neutrophils and increased production of tumor necrosis factor-α in bronchoalveolar lavage fluid were inhibited in the early inflammatory phase. Pravastatin effectively inhibited the increase of lung hydroxyproline content induced by bleomycin. Furthermore, pravastatin reduced the increased expression of transforming growth factor (TGF)-β1, connective tissue growth factor (CTGF), RhoA and cyclin D1. The increased levels of TGF-β1 and CTGF mRNA expression were also significantly inhibited by pravastatin. 4. Pravastatin effectively attenuated bleomycin-induced lung injury and pulmonary fibrosis in mice. Our results provide evidence for the therapeutic potential of pravastatin in the treatment of acute lung injury and pulmonary fibrosis.

Luteolin ameliorates experimental lung fibrosis both in vivo and in vitro: implications for therapy of lung fibrosis

Lonicera japonica (Caprifoliaceae) has been known as an anti-inflammatory herb in traditional Chinese medicine for thousands of years and is used constantly for upper respiratory tract infections. Luteolin, an active flavonoid compound isolated from Lonicera japonica, has a spectrum of biological activities, especially with antioxidative and anti-inflammatory properties. However, whether luteolin has a direct inhibitory effect on lung fibrosis has not been established. In this study, we examined the effects of luteolin on lung fibrosis both in vivo and in vitro. We found that oral administration of luteolin (10 mg/kg) efficiently suppressed the neutrophil infiltration as well as TNF-α and IL-6 elevation in the bronchoalveolar lavage fluid in bleomycin-instilled C57BL/6J mice. Luteolin also alleviated collagen deposition, TGF-β1 expression, and lung fibrosis upon bleomycin instillation. A similar tendency was observed in both early and delayed luteolin-treated groups. Next, our in vitro studies showed that luteolin inhibited TGF-β1-induced α-SMA, type I collagen, and vimentin expression in primary cultured mouse lung fibroblasts. Moreover, luteolin significantly blocked TGF-β1-mediated epithelial marker (E-cadherin) downregulation and mesenchymal cell markers (fibronectin and vimentin) upregulation, as well as retaining epithelial morphology in human alveolar epithelial-derived A549 cells. Additionally, luteolin could attenuate TGF-β1-induced Smad3 phosphorylation in both lung fibroblasts and A549 cells. These findings suggest that luteolin has a potent antifibrotic activity; this effect was mediated, at least in part, by inhibition of lung inflammation and suppression of myofibroblast differentiation as well as epithelial-to-mesenchymal transition.

Role of growth factors in acute lung injury induced by paraquat in a rat model

Paraquat (PQ) can cause acute lung injury in humans and experimental animals. However, the role of growth factors in the progression of injury has not been clearly established. We developed an animal model of PQ-induced lung injury using Wistar rats. One milliliter of PQ solution (30, 60, and 120 mg/kg) was applied through the lavage, while the same amount of vehicle was applied to control rats. Based on histopathology, the lungs of some animals exposed to PQ showed acute fulmination, resulting in death, while others showed a more protracted injury, resulting in typical pulmonary fibrosis at 21 days. Using this PQ-poisoned rat model, we examined the intrapulmonary gene expression and circulatory level of cytokines and growth factors at 8 hours, 24 hours, 3 days, 7 days, 14 days, and 21 days after PQ administration. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrated that the gene expression levels of interleukin-1 beta and interleukin-6 were significantly increased at 21 days after PQ challenge compared with the controls. The mRNA expression of tumor necrosis factor-alpha was also significantly increased except on days 14 and 21 after PQ treatment. Moreover, PQ-treated rats showed enhanced gene expression of growth factors such as platelet-derived growth factor-A and insulin-like growth factor-1 at 21 days and transforming growth factor-beta 1 at 14 days. ELISA results showed the circulatory level of cytokines and growth factors coincided with intrapulmonary gene expression. The synergistic effects of these molecules are presumed to cause pulmonary damage due to PQ challenge and may become targets of treatment.

Transforming growth factor-β1 induces expression of human coagulation factor XII via Smad3 and JNK signaling pathways in human lung fibroblasts

Coagulation factor XII (FXII) is a liver-derived serine protease involved in fibrinolysis, coagulation, and inflammation. The regulation of FXII expression is largely unknown. Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine that has been linked to several pathological processes, including tissue fibrosis by modulating procoagulant and fibrinolytic activities. This study investigated whether TGF-beta1 may regulate FXII expression in human lung fibroblasts. Treatment of human lung fibroblasts with TGF-beta1 resulted in a time-dependent increase in FXII production, activation of p44/42, p38, JNK, and Akt, and phosphorylation and translocation into the nucleus of Smad3. However, TGF-beta1-induced FXII expression was repressed only by the JNK inhibitor and JNK and Smad3 antisense oligonucleotides but not by MEK, p38, or phosphoinositide 3-kinase blockers. JNK inhibition had no effect on TGF-beta1-induced Smad3 phosphorylation, association with Smad4, and its translocation into the nucleus but strongly suppressed Smad3-DNA complex formation. FXII promoter analysis revealed that the -299/+1 region was sufficient for TGF-beta1 to induce FXII expression. Sequence analysis of this region detected a potential Smad-binding element at position -272/-269 (SBE-(-272/-269)). Chromatin immunoprecipitation and streptavidin pulldown assays demonstrated TGF-beta1-dependent Smad3 binding to SBE-(-272/-269). Mutation or deletion of SBE-(-272/-269) substantially reduced TGF-beta1-mediated activation of the FXII promoter. Clinical relevance was demonstrated by elevated FXII levels and its co-localization with fibroblasts in the lungs of patients with acute respiratory distress syndrome. Our results show that JNK/Smad3 pathway plays a critical role in TGF-beta1-induced FXII expression in human lung fibroblasts and implicate its possible involvement in pathological conditions characterized by elevated TGF-beta1 levels.