BIPHASIC EFFECTS OF SELECTIVE INHIBITION OF TRANSFORMING GROWTH FACTOR β1 ACTIVIN RECEPTOR-LIKE KINASE ON LPS-INDUCED LUNG INJURY

Wnt/β-Catenin Participates in the Repair of Acute Respiratory Distress Syndrome-Associated Early Pulmonary Fibrosis via Mesenchymal Stem Cell Microvesicles

Purpose

The main aim of the present study was to establish whether mesenchymal stem cell microvesicles (MSC MVs) exert anti-fibrotic effects and investigate the mechanisms underlying these effects in a mouse model of acute respiratory distress syndrome (ARDS)-associated early pulmonary fibrosis.

Methods

An ARDS-associated pulmonary fibrosis model was established in mice by an intratracheal injection of lipopolysaccharide (LPS). At 1, 3, and 7 days after LPS-mediated injury, the lungs of mice treated with MSC MVs and untreated controls were carefully excised and fibrosis was assessed based on the extent of collagen deposition. In addition, the development of epithelial–mesenchymal transition (EMT) was evaluated based on loss of E-cadherin and zona occludens-1 (ZO-1) along with the acquisition of α-smooth muscle actin (α-SMA) and N-cadherin. Nuclear translocation and β-catenin expression analyses were also used to evaluate activation of the Wnt/β-catenin signaling pathway.

Results

Blue-stained collagen fibers were evident as early as 7 days after LPS injection. Treatment with MSC MVs suppressed pathological progression to a significant extent. MSC MVs markedly reversed the upregulation of N-cadherin and α-SMA and attenuated the downregulation of E-cadherin and ZO-1. The expression and nuclear translocation of β-catenin were clearly decreased on day 7 after MSC MV treatment.

Conclusion

Analyses indicated that MSC MVs could ameliorate ARDS-associated early pulmonary fibrosis via the suppression of EMT and might be related to Wnt/β-catenin transition signaling.

Effects of Ultrashort Wave Therapy on Inflammation and Macrophage Polarization after Acute Lung Injury in Rats

Acute lung injury (ALI) features dysregulated pulmonary inflammation. Ultrashort waves (USWs) exert anti-inflammatory effects but no studies have evaluated their activity in ALI. Herein, we used an in vivo lipopolysaccharide (LPS)-induced ALI model to investigate whether the anti-inflammatory activity of USWs is mediated by altering the polarization of M1 to M2 macrophages. Twenty-four male Sprague-Dawley rats were randomly divided into control, untreated ALI, and ALI treated with USW groups (n = 8 in each group). ALI was induced by intratracheal LPS instillation. Rats in the USW group were treated for 15 min at 0, 4, and 8 h after a single LPS intratracheal instillation. Histopathologic examination, wet/dry lung weight ratio, enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, and western blot analyses were performed to evaluate the degree of lung injury and to determine macrophage phenotypes. Histopathologic examination disclosed attenuation of ALI, with reduced alveolar hemorrhage and neutrophilic infiltration in the USW group. Serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were significantly decreased after USW therapy. Moreover, the messenger RNA (mRNA) expressions of TNF-α and IL-1β were significantly decreased in the USW group, whereas the mRNA expression of Arginase 1 (Arg1) and the protein expression of mannose receptor significantly increased in comparison with the untreated ALI group. We conclude that USW therapy may attenuate inflammation in LPS-induced ALI through the modulation of macrophage polarization. © 2021 Bioelectromagnetics Society.

A novel approach for monitoring TGF-β signaling in vivo in colon cancer

The TGF-β receptor kinase inhibitors (TRKI) have been reported to inhibit tumorigenicity in colon cancer. However, there is no direct evidence showing that these inhibitors function through inhibiting the TGF-β- mediated tumor-promoting effects in vivo. We established a TGF-β inducible reporter system by inserting a luciferase reporter gene to the vector downstream of TGF-β-inducible promoter elements, and transfected it into colon cancer cell lines. TRKIs SB431542 and LY2109761 were used to treat TGF-β inducible cells in vitro and in vivo. The luciferase activity was induced 5.24-fold by TGF-β in CT26 inducible cells, while it was marginally changed in MC38 inducible cells lacking Smad4 expression. Temporary treatment of mice with SB431542 inhibited the TGF-β pathway and TGF-β induced bioluminescence activity in vivo. Long-term treatment with LY2109761 inhibited tumorigenicity and liver metastasis in vivo in concomitant with reduced luciferase activity in the tumor. In this study, we established a model to monitor the TGF-β pathway in vivo and to compare the antitumor effects of TRKIs. Based on this novel experimental tool, we provided direct evidences that LY2109761 inhibits tumorigenicity and liver metastasis by blocking the pro-oncogenic functions of TGF-β in vivo.

Telomere shortening activates TGF-β/Smads signaling in lungs and enhances both lipopolysaccharide and bleomycin-induced pulmonary fibrosis

Telomere shortening is associated with idiopathic pulmonary fibrosis (IPF), a high-morbidity and high-mortality lung disease of unknown etiology. However, the underlying mechanisms remain largely unclear. In this study, wild-type (WT) mice with normal telomeres and generation 3 (G3) or G2 telomerase RNA component (TERC) knockout Terc^-/- mice with short telomeres were treated with and without lipopolysaccharide (LPS) or bleomycin by intratracheal injection. We show that under LPS induction, G3 Terc^-/- mice develop aggravated pulmonary fibrosis as indicated by significantly increased α-SMA, collagen I and hydroxyproline content. Interestingly, TGF-β/Smads signaling is markedly activated in the lungs of G3 Terc^-/- mice, as indicated by markedly elevated levels of phosphorylated Smad3 and TGF-β1, compared with those of WT mice. This TGF-β/Smads signaling activation is significantly increased in the lungs of LPS-treated G3 Terc^-/- mice compared with those of LPS-treated WT or untreated G3 Terc^-/- mice. A similar pattern of TGF-β/Smads signaling activation and the enhancing role of telomere shortening in pulmonary fibrosis are also confirmed in bleomycin-induced model. Moreover, LPS challenge produced more present cellular senescence, apoptosis and infiltration of innate immune cells, including macrophages and neutrophils in the lungs of G3 Terc^-/- mice, compared with WT mice. To our knowledge, this is the first time to report telomere shortening activated TGF-β/Smads signaling in lungs. Our data suggest that telomere shortening cooperated with environment-induced lung injury accelerates the development of pulmonary fibrosis, and telomere shortening confers an inherent enhancing factor to the genesis of IPF through activation of TGF-β/Smads signaling.

Pirfenidone ameliorates lipopolysaccharide-induced pulmonary inflammation and fibrosis by blocking NLRP3 inflammasome activation

Acute respiratory distress syndrome(ARDS)is a severe clinical disorder characterized by its acute onset, diffuse alveolar damage, intractable hypoxemia, and non-cardiogenic pulmonary edema. Acute lung injury(ALI) can trigger persistent lung inflammation and fibrosis through activation of the NLRP3 inflammasome and subsequent secretion of mature IL-1β, suggesting that the NLRP3 inflammasome is a potential therapeutic target for ALI, for which new therapeutic approaches are needed. Our present study aims to assess whether pirfenidone,with anti-fibrotic and anti-inflammatory properties, can improve LPS-induced inflammation and fibrosis by inhibiting NLRP3 inflammasome activation. Male C57BL/6 J mice were intratracheally injected with LPS to induce ALI. Mice were administered pirfenidone by oral gavage throughout the entire experimental course. The mouse macrophage cell line (J774 A.1) was incubated with LPS and ATP, with or without PFD pre-treatment. We demonstrated that PFD remarkably ameliorated LPS-induced pulmonary inflammation and fibrosis and reduced IL-1β and TGF-β1 levels in bronchoalveolar lavage fluid(BALF). Pirfenidone substantially reduced NLRP3 and ASC expression and inhibited caspase-1 activation and IL-1β maturation in lung tissues. In vitro, the experiments revealed that PFD significantly suppressed LPS/ATP-induced production of reactive oxygen species (ROS) and decreased caspase-1 activation and the level of IL-1β in J774 A.1 cells. Taken together, the administration of PFD reduced LPS-induced lung inflammation and fibrosis by blocking NLRP3 inflammasome activation and subsequent IL-1β secretion. These findings indicated that PFD can down-regulate NLRP3 inflammasome activation and that it may offer a promising therapeutic approach for ARDS patients.

Therapeutic effect of ulinastatin on pulmonary fibrosis via downregulation of TGF‑β1, TNF‑α and NF‑κB

Pulmonary fibrosis is a chronic, progressive, lethal lung disease characterized by alveolar cell necrosis and dysplasia of interstitial fibrotic tissue, resulting in loss of lung function and eventual respiratory failure. Previously, glucocorticoid drugs were used to treat this lung disorder. However, positive responses were recorded in less than half of treated patients and the cytotoxicity caused by high dosage treatment is still a concern. The present study investigated whether ulinastatin, a typical urinary trypsin inhibitor that mitigates numerous inflammatory responses, could be a treatment option for lung fibrosis. The results demonstrated that ulinastatin had the ability to ameliorate interstitial fibrosis and alveolar exudates and to protect against lung diseases induced by smoke, irradiation or silica particles. The mechanism of ulinastatin resulted in the downregulation of inflammatory cascades: Transforming growth factor-β1, tumor necrosis factor-α and nuclear factor-κB, as demonstrated by western blotting and ELISA. Ulinastatin treatment with a high dose (100,000 U/kg body weight/day) resulted in an attenuated inflammatory response, and inhibited fibrosis formation in lungs, suggesting that ulinastatin may become a part of a clinical therapeutic strategy.

Protective Effects of Hydrogen-Rich Saline Against Lipopolysaccharide-Induced Alveolar Epithelial-to-Mesenchymal Transition and Pulmonary Fibrosis

BACKGROUND Fibrotic change is one of the important reasons for the poor prognosis of patients with acute respiratory distress syndrome (ARDS). The present study investigated the effects of hydrogen-rich saline, a selective hydroxyl radical scavenger, on lipopolysaccharide (LPS)-induced pulmonary fibrosis. MATERIAL AND METHODS Male ICR mice were divided randomly into 5 groups: Control, LPS-treated plus vehicle treatment, and LPS-treated plus hydrogen-rich saline (2.5, 5, or 10 ml/kg) treatment. Twenty-eight days later, fibrosis was assessed by determination of collagen deposition, hydroxyproline, and type I collagen levels. Development of epithelial-to-mesenchymal transition (EMT) was identified by examining protein expressions of E-cadherin and α-smooth muscle actin (α-SMA). Transforming growth factor (TGF)-β1 content, total antioxidant capacity (T-AOC), malondialdehyde (MDA) content, catalase (CAT), and superoxide dismutase (SOD) activity were determined. RESULTS Mice exhibited increases in collagen deposition, hydroxyproline, type I collagen contents, and TGF-β1 production in lung tissues after LPS treatment. LPS-induced lung fibrosis was associated with increased expression of α-SMA, as well as decreased expression of E-cadherin. In addition, LPS treatment increased MDA levels but decreased T-AOC, CAT, and SOD activities in lung tissues, indicating that LPS induced pulmonary oxidative stress. Hydrogen-rich saline treatment at doses of 2.5, 5, or 10 ml/kg significantly attenuated LPS-induced pulmonary fibrosis. LPS-induced loss of E-cadherin in lung tissues was largely reversed, whereas the acquisition of α-SMA was dramatically decreased by hydrogen-rich saline treatment. In addition, hydrogen-rich saline treatment significantly attenuated LPS-induced oxidative stress. CONCLUSIONS Hydrogen-rich saline may protect against LPS-induced EMT and pulmonary fibrosis through suppressing oxidative stress.

Chronic lung injury in the neonatal rat: up-regulation of TGFβ1 and nitration of IGF-R1 by peroxynitrite as likely contributors to impaired alveologenesis

Postnatal alveolarization is regulated by a number of growth factors, including insulin-like growth factor-I (IGF-I) acting through the insulin-like growth factor receptor-1 (IGF-R1). Exposure of the neonatal rat lung to 60% O2 for 14 days results in impairments of lung cell proliferation, secondary crest formation, and alveologenesis. This lung injury is mediated by peroxynitrite and is prevented by treatment with a peroxynitrite decomposition catalyst. We hypothesized that one of the mechanisms by which peroxynitrite induces lung injury in 60% O2 is through nitration and inactivation of critical growth factors or their receptors. Increased nitration of both IGF-I and IGF-R1 was evident in 60% O2-exposed lungs, which was reversible by concurrent treatment with a peroxynitrite decomposition catalyst. Increased nitration of the IGF-R1 was associated with its reduced activation, as assessed by IGF-R1 phosphotyrosine content. IGF-I displacement binding plots were conducted in vitro using rat fetal lung distal epithelial cells which respond to IGF-I by an increase in DNA synthesis. When IGF-I was nitrated to a degree similar to that observed in vivo there was minimal, if any, effect on IGF-I displacement binding. In contrast, nitrating cell IGF-R1 to a similar degree to that observed in vivo completely prevented specific binding of IGF-I to the IGF-R1, and attenuated an IGF-I-mediated increase in DNA synthesis. Additionally, we hypothesized that peroxynitrite also impairs alveologenesis by being an upstream regulator of the growth inhibitor, TGFβ1. That 60% O2-induced impairment of alveologenesis was mediated in part by TGFβ1 was confirmed by demonstrating an improvement in secondary crest formation when 60% O2-exposed pups received concurrent treatment with the TGFß1 activin receptor-like kinase, SB 431542. That the increased TGFβ1 content in lungs of pups exposed to 60% O2 was regulated by peroxynitrite was confirmed by its attenuation by concurrent treatment with a peroxynitrite decomposition catalyst. We conclude that peroxynitrite contributes to the impaired alveologenesis observed following the exposure of neonatal rats to 60% O2 both by preventing binding of IGF-I to the IGF-R1, secondary to nitration of the IGF-R1, and by causing an up-regulation of the growth inhibitor, TGFβ1.

A rat model of smoke inhalation injury

CONTEXT

Smoke inhalation injury is the leading cause of acute respiratory failure in critical burn victims. Advances in the treatment of smoke inhalation injury have been limited in the past years. To further explore the pathogenesis, stable and practical animal models are necessary.

OBJECTIVE

To develop a rat model of smoke inhalation injury.

MATERIALS AND METHODS

The smoke composition including the particulate matters, irritant gases, chemical carcinogens was measured. The blood gas values, pro-inflammatory and protein concentration in bronchoalveolar lavage fluid and lung wet to dry weight ratio were assayed. Pathological evaluations of pulmonary were performed at 24 h, 96 h, 7 days and 28 days post-injury. Masson-Goldner trichrome staining was performed on day 7 and 28 post-injury, along with the measurement of hydroxyproline and collagen I and III.

RESULTS

In our present animal model, smoke inhalation caused a significant hypoxemia and CO poisoning. A surge of pro-inflammatory response and microvascular hyperpermeability with neutrophils accumulations were also found in our animal model. At 24 h post-smoke inhalation, the hematoxylin and eosin results exhibited that there were inflammatory exudates and diffuse hemorrhage in the lung tissue with significant edema. With the time going, the lung injuries appeared at alveolar collapse and alveolar septum thickening, which indicated that smoke inhalation further induced damage to lung parenchyma. Specially, the markedly collagen deposition appeared at 28 days post-injury indicated that pulmonary fibrosis happened.

DISCUSSION AND CONCLUSION

In conclusion, this rat smoke inhalation injury model induced by our novel self-made smoke generator could be used for acute and chronic lung injury experiments.

Concurrent inhibition of TGF-β and mitogen driven signaling cascades in Dupuytren's disease - non-surgical treatment strategies from a signaling point of view

Dupuytren's disease (DD) is a benign progressive fibro-proliferative disorder of the fascia palmaris of the hand. Currently, treatment consists of surgical excision with a relatively high recurrence rate and risk of complications. To improve long-term outcome of DD treatment, research focus has shifted towards molecular targets for DD as an alternative to surgery. Therefore, complete and exact understanding of the cause of DD is needed. Transforming growth factor (TGF)-β is considered a key player in DD. We recently showed that increased TGF-β expression in DD correlates not only with elevated expression and activation of downstream Smad effectors, but also with overactive ERK1/2 MAP kinase signaling. Both TGF-β/Smad and non-Smad signaling pathways increase expression of key fibrotic markers and contractility of Dupuytren's myofibroblasts. What is not yet known is whether these two signaling cascades each accelerate DD autonomously, successively or in conjunction. Elucidation of this mechanism will help develop new potential non-surgical treatments. We hypothesize that TGF-β-induced short-term activation of the MAPK pathway leads to an autonomous non-Smad driven fibrosis. Therefore, successful treatment strategies will target not only TGF-β/Smad, but also intracellular MAPK signaling. In this review we discuss possible scenarios in which such a drift from TGF-β induced Smad signaling to autonomous non-Smad signaling could be observed in DD. The potential therapeutic effects of small cytokine signaling cascades inhibitors, such as TGF-β type I receptor-, (pan-) tyrosine- or ERK1/2 MAP-kinase inhibitor will be highlighted. To abrogate the fibrotic trait and the recurrence of DD, we speculate on sequential and co-application of such molecules in order to provide possible new non-operative strategies for DD.

Calpain mediates pulmonary vascular remodeling in rodent models of pulmonary hypertension, and its inhibition attenuates pathologic features of disease

Pulmonary hypertension is a severe and progressive disease, a key feature of which is pulmonary vascular remodeling. Several growth factors, including EGF, PDGF, and TGF-β1, are involved in pulmonary vascular remodeling during pulmonary hypertension. However, increased knowledge of the downstream signaling cascades is needed if effective clinical interventions are to be developed. In this context, calpain provides an interesting candidate therapeutic target, since it is activated by EGF and PDGF and has been reported to activate TGF-β1. Thus, in this study, we examined the role of calpain in pulmonary vascular remodeling in two rodent models of pulmonary hypertension. These data showed that attenuated calpain activity in calpain-knockout mice or rats treated with a calpain inhibitor resulted in prevention of increased right ventricular systolic pressure, right ventricular hypertrophy, as well as collagen deposition and thickening of pulmonary arterioles in models of hypoxia- and monocrotaline-induced pulmonary hypertension. Additionally, inhibition of calpain in vitro blocked intracellular activation of TGF-β1, which led to attenuated Smad2/3 phosphorylation and collagen synthesis. Finally, smooth muscle cells of pulmonary arterioles from patients with pulmonary arterial hypertension showed higher levels of calpain activation and intracellular active TGF-β. Our data provide evidence that calpain mediates EGF- and PDGF-induced collagen synthesis and proliferation of pulmonary artery smooth muscle cells via an intracrine TGF-β1 pathway in pulmonary hypertension.