Plasminogen activator inhibitor-1 suppresses profibrotic responses in fibroblasts from fibrotic lungs

Uric acid-driven NLRP3 inflammasome activation triggers lens epithelial cell senescence and cataract formation

Excessive uric acid (UA) is associated with age-related cataract. A previous study showed that a high UA level in the aqueous humor stimulated the senescence of lens epithelial cells (LECs), leading to cataract progression. To better understand the underlying mechanisms, we investigated UA-driven senescence in human lens tissue samples obtained during surgery, rat lens organ cultures, and in vivo experiments, using senescence-associated β-galactosidase (SA-β-gal) staining, electronic microscopy, Western blotting, and histological analyses. Initially, we identified markedly higher expressions of NLRP3 and caspase-1 in the lens capsules of hyper-uricemic patients compared to normo-uricemic patients. This increase was accompanied by a significant rise in the SA-β-gal positive rate. We next built a cataract model in which rat lenses in an organ culture system were treated with an increasing dosage of UA. Notably, opacification was apparent in the lenses treated with 800 μM of UA starting on the fifth day. Mechanistically, UA treatment not only significantly induced the expression of NLRP3, caspase-1, and IL-1β, but also upregulated the levels of SA-β-gal and the senescence regulators p53 and p21. These effects were fully reversed, and lens opacification was ameliorated by the addition of MCC950, a selective NLRP3 antagonist. Moreover, an in vivo model showed that intravitreal UA injection rapidly induced cataract phenotypes within 21 days, an effect significantly mitigated by co-injection with MCC950. Together, our findings suggest that targeting the UA-induced NLRP3 inflammasome with MCC950 could be a promising strategy for preventing cataract formation associated with inflammageing.

PAI-1 mediates TGF-β1-induced myofibroblast activation in tenocytes via mTOR signaling

Transforming growth factor-beta (TGF-β1) induces plasminogen activator inhibitor 1 (PAI-1) to effect fibrotic pathologies in several organs including tendon. Recent data implicated PAI-1 with inhibition of phosphatase and tensin homolog (PTEN) suggesting that PAI-1-induced adhesions involves phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) signaling. Ergo, we investigated effects of TGF-β1, PAI-1, and mTOR signaling crosstalk on myofibroblast activation, senescence, and proliferation in primary flexor tenocytes from wild-type (WT) and PAI-1 knockout (KO) mice. PAI-1 deletion blunted TGF-β1-induced myofibroblast activation in murine flexor tenocytes and increased the gene expression of Mmp-2 to confer protective effects against fibrosis. While TGF-β1 significantly reduced phosphorylation of PTEN in WT cells, PAI-1 deletion rescued the activation of PTEN. Despite that, there were no differences in TGF-β1-induced activation of mTOR signaling (AKT, 4EBP1, and P70S6K) in WT or KO tenocytes. Phenotypic changes in distinct populations of WT or KO tenocytes exhibiting high or low mTOR activity were then examined. TGF-β1 increased alpha-smooth muscle actin abundance in WT cells exhibiting high mTOR activity, but this increase was blunted in KO cells exhibiting high 4EBP1 activity but not in cells exhibiting high S6 activity. DNA damage (γH2AX) was increased with TGF-β1 treatment in WT tenocytes but was blunted in KO cells exhibiting high mTOR activity. Increased mTOR activity enhanced proliferation (Ki67) in both WT and KO tenocytes. These findings point to a complex nexus of TGF-β1, PAI-1, and mTOR signaling in regulating proliferation, myofibroblast differentiation, and senescence in tenocytes, which could define therapeutic targets for chronic tendon adhesions and other fibrotic pathologies.

Targeting the PAI-1 Mechanism with a Small Peptide Increases the Efficacy of Alteplase in a Rabbit Model of Chronic Empyema

The incidence of empyema is increasing and associated with a mortality rate of 20% in patients older than 65 years. Since 30% of patients with advanced empyema have contraindications to surgical treatment, novel, low-dose, pharmacological treatments are needed. A Streptococcus pneumoniae-induced rabbit model of chronic empyema recapitulates the progression, loculation, fibrotic repair, and pleural thickening of human disease. Treatment with single chain (sc) urokinase (scuPA) or tissue type (sctPA) plasminogen activators in doses 1.0-4.0 mg/kg were only partially effective in this model. Docking Site Peptide (DSP; 8.0 mg/kg), which decreased the dose of sctPA for successful fibrinolytic therapy in acute empyema model did not improve efficacy in combination with 2.0 mg/kg scuPA or sctPA. However, a two-fold increase in either sctPA or DSP (4.0 and 8.0 mg/kg or 2.0 and 16.0 mg/kg sctPA and DSP, respectively) resulted in 100% effective outcome. Thus, DSP-based Plasminogen Activator Inhibitor 1-Targeted Fibrinolytic Therapy (PAI-1-TFT) of chronic infectious pleural injury in rabbits increases the efficacy of alteplase rendering ineffective doses of sctPA effective. PAI-1-TFT represents a novel, well-tolerated treatment of empyema that is amenable to clinical introduction. The chronic empyema model recapitulates increased resistance of advanced human empyema to fibrinolytic therapy, thus allowing for studies of muti-injection treatments.

Attenuation of Ventilation-Enhanced Epithelial–Mesenchymal Transition through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Model

Mechanical ventilation (MV) used in patients with acute lung injury (ALI) induces lung inflammation and causes fibroblast proliferation and excessive collagen deposition—a process termed epithelial–mesenchymal transition (EMT). Phosphoinositide 3-kinase-γ (PI3K-γ) is crucial in modulating EMT during the reparative phase of ALI; however, the mechanisms regulating the interactions among MV, EMT, and PI3K-γ remain unclear. We hypothesized that MV with or without bleomycin treatment would increase EMT through the PI3K-γ pathway. C57BL/6 mice, either wild-type or PI3K-γ-deficient, were exposed to 6 or 30 mL/kg MV for 5 h after receiving 5 mg/kg AS605240 intraperitoneally 5 days after bleomycin administration. We found that, after bleomycin exposure in wild-type mice, high-tidal-volume MV induced substantial increases in inflammatory cytokine production, oxidative loads, Masson’s trichrome staining level, positive staining of α-smooth muscle actin, PI3K-γ expression, and bronchial epithelial apoptosis (p < 0.05). Decreased respiratory function, antioxidants, and staining of the epithelial marker Zonula occludens-1 were also observed (p < 0.05). MV-augmented bleomycin-induced pulmonary fibrogenesis and epithelial apoptosis were attenuated in PI3K-γ-deficient mice, and we found pharmacological inhibition of PI3K-γ activity through AS605240 (p < 0.05). Our data suggest that MV augmented EMT after bleomycin-induced ALI, partially through the PI3K-γ pathway. Therapy targeting PI3K-γ may ameliorate MV-associated EMT.

Pharmacological inhibition of PAI-1 alleviates cardiopulmonary pathologies induced by exposure to air pollutants PM2.5

Numerous studies have established that acute or chronic exposure to environmental pollutants like particulate matter (PM) leads to the development of accelerated aging related pathologies including pulmonary and cardiovascular diseases, and thus air pollution is one of the major global threats to human health. Air pollutant particulate matter 2.5 (PM_2.5)-induced cellular dysfunction impairs tissue homeostasis and causes vascular and cardiopulmonary damage. To test a hypothesis that elevated plasminogen activator inhibitor-1 (PAI-1) levels play a pivotal role in air pollutant-induced cardiopulmonary pathologies, we examined the efficacy of a drug-like novel inhibitor of PAI-1, TM5614, in treating PM_2.5-induced vascular and cardiopulmonary pathologies. Results from biochemical, histological, and immunohistochemical studies revealed that PM_2.5 increases the circulating levels of PAI-1 and thrombin and that TM5614 treatment completely abrogates these effects in plasma. PM_2.5 significantly augments the levels of pro-inflammatory cytokine interleukin-6 (IL-6) in bronchoalveolar lavage fluid (BALF), and this also can be reversed by TM5614, indicating its efficacy in amelioration of PM_2.5-induced increases in inflammatory and pro-thrombotic factors. TM5614 reduces PM_2.5-induced increased levels of inflammatory markers cluster of differentiation 107 b (Mac3) and phospho-signal transducer and activator of transcription-3 (pSTAT3), adhesion molecule vascular cell adhesion molecule 1 (VCAM1), and apoptotic marker cleaved caspase 3. Longer exposure to PM_2.5 induces pulmonary and cardiac thrombosis, but TM5614 significantly ameliorates PM_2.5-induced vascular thrombosis. TM5614 also reduces PM_2.5-induced increased blood pressure and heart weight. In vitro cell culture studies revealed that PM_2.5 induces the levels of PAI-1, type I collagen, fibronectin (Millipore), and sterol regulatory element binding protein-1 and 2 (SREBP-1 and SREBP-2), transcription factors that mediate profibrogenic signaling, in cardiac fibroblasts. TM5614 abrogated that stimulation, indicating that it may block PM_2.5-induced PAI-1 and profibrogenic signaling through suppression of SREBP-1 and 2. Furthermore, TM5614 blocked PM_2.5-mediated suppression of nuclear factor erythroid related factor 2 (Nrf2), a major antioxidant regulator, in cardiac fibroblasts. Pharmacological inhibition of PAI-1 with TM5614 is a promising therapeutic approach to control air pollutant PM_2.5-induced cardiopulmonary and vascular pathologies.

Inhibition of NF-κB by ACT001 reduces fibroblast activity in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease of unknown etiology and poor prognosis. In IPF, aberrant extracellular matrix production by activated, hyperproliferative fibroblasts drives disease progression but the exact mechanisms by which this occurs remains undefined. The transcription factor nuclear factor kappa-B (NF-ĸB) has been suggested as a potential therapeutic target in IPF and therefore the aim of this study was to investigate the efficacy of ACT001, an NF-ĸB inhibitor, on primary fibroblasts derived from patients with and without IPF. Primary lung fibroblasts derived from eight patients with IPF and eight age-matched non-diseased controls (NDC) were treated with 0-10 µM ACT001 and the effects on fibroblast activity (viability and proliferation, fibroblast-to-myofibroblast transition, fibronectin expression), interleukin (IL)-6 and IL-8 cytokine release were quantified. ACT001 inhibited fibroblast activity in a concentration-dependent manner in both groups of fibroblasts. ACT001 inhibited IL-6 but not IL-8 production in unstimulated fibroblasts. ACT001 is a water-soluble compound with a stable half-life in plasma, thus making it an attractive candidate for further investigation as a therapeutic in IPF. This study adds to the growing body of literature that demonstrates anti-fibrotic activity of NF-ĸB inhibition in the context of IPF.

Atorvastatin Inhibits Endothelial PAI-1-Mediated Monocyte Migration and Alleviates Radiation-Induced Enteropathy

Intestinal injury is observed in cancer patients after radiotherapy and in individuals exposed to radiation after a nuclear accident. Radiation disrupts normal vascular homeostasis in the gastrointestinal system by inducing endothelial damage and senescence. Despite advances in medical technology, the toxicity of radiation to healthy tissue remains an issue. To address this issue, we investigated the effect of atorvastatin, a commonly prescribed hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor of cholesterol synthesis, on radiation-induced enteropathy and inflammatory responses. We selected atorvastatin based on its pleiotropic anti-fibrotic and anti-inflammatory effects. We found that atorvastatin mitigated radiation-induced endothelial damage by regulating plasminogen activator inhibitor-1 (PAI-1) using human umbilical vein endothelial cells (HUVECs) and mouse model. PAI-1 secreted by HUVECs contributed to endothelial dysfunction and trans-endothelial monocyte migration after radiation exposure. We observed that PAI-1 production and secretion was inhibited by atorvastatin in irradiated HUVECs and radiation-induced enteropathy mouse model. More specifically, atorvastatin inhibited PAI-1 production following radiation through the JNK/c-Jun signaling pathway. Together, our findings suggest that atorvastatin alleviates radiation-induced enteropathy and supports the investigation of atorvastatin as a radio-mitigator in patients receiving radiotherapy.

Gold nanoparticles inhibit activation of cancer-associated fibroblasts by disrupting communication from tumor and microenvironmental cells

Cancer-associated fibroblasts (CAFs) are a major constituent of the tumor microenvironment (TME) and an important contributor to cancer progression and therapeutic resistance. Regulation of CAF activation is a promising strategy to influence cancer outcomes. Here, we report that ovarian cancer cells (OCs) and TME cells promote the activation of ovarian CAFs, whereas gold nanoparticles (GNPs) of 20 nm in diameter inhibit the activation, as demonstrated by the changes in cell morphology, migration, and molecular markers. GNPs exert the effect by altering the levels of multiple fibroblast activation or inactivation proteins, such as TGF-β1, PDGF, uPA and TSP1, secreted by OCs and TME cells. Thus, GNPs represent a potential tool to help understand multicellular communications existing in the TME as well as devise strategies to disrupt the communication.

Prenatal Exposure to Electronic-Cigarette Aerosols Leads to Sex-Dependent Pulmonary Extracellular-Matrix Remodeling and Myogenesis in Offspring Mice

Electronic-cigarette (e-cig) vaping is a serious concern, as many pregnant women who vape consider it safe. However, little is known about the harmful effects of prenatal e-cig exposure on adult offspring, especially on extracellular-matrix (ECM) deposition and myogenesis in the lungs of offspring. We evaluated the biochemical and molecular implications of maternal exposure during pregnancy to e-cig aerosols on the adult offspring of both sexes, with a particular focus on pulmonary ECM remodeling and myogenesis. Pregnant CD-1 mice were exposed to e-cig aerosols with or without nicotine, throughout gestation, and lungs were collected from adult male and female offspring. Compared with the air-exposed control group, female mice exposed to e-cig aerosols, with or without nicotine, demonstrated increased lung protein abundance of LEF-1 (lymphoid enhancer-binding factor 1), fibronectin, and E-cadherin, whereas altered E-cadherin and PPARγ (peroxisome proliferator-activated receptor γ) levels were observed only in males exposed to e-cig aerosols with nicotine. Moreover, lipogenic and myogenic mRNAs were dysregulated in adult offspring in a sex-dependent manner. PAI-1 (plasminogen activator inhibitor-1), one of the ECM regulators, was significantly increased in females exposed prenatally to e-cig aerosols with nicotine and in males exposed to e-cig aerosols compared with control animals exposed to air. MMP9 (matrix metalloproteinase 9), a downstream target of PAI-1, was downregulated in both sexes exposed to e-cig aerosols with nicotine. No differences in lung histology were observed among any of the treatment groups. Overall, adult mice exposed prenatally to e-cig aerosols could be predisposed to developing pulmonary disease later in life. Thus, these findings suggest that vaping during pregnancy is unsafe and increases the propensity for later-life interstitial lung diseases.

Pathological Insight into 5-HT2B Receptor Activation in Fibrosing Interstitial Lung Diseases

Interstitial lung disease (ILD) encompasses a heterogeneous group of more than 200 conditions, of which primarily idiopathic pulmonary fibrosis (IPF), idiopathic nonspecific interstitial pneumonia, hypersensitivity pneumonitis, ILD associated with autoimmune diseases and sarcoidosis may present a progressive fibrosing (PF) phenotype. Despite different aetiology and histopathological patterns, the PF-ILDs have similarities regarding disease mechanisms with self-sustaining fibrosis, which suggests that the diseases may share common pathogenetic pathways. Previous studies show an enhanced activation of serotonergic signaling in pulmonary fibrosis, and the serotonin (5-HT)₂ receptors have been implicated to have important roles in observed profibrotic actions. Our research findings in support by others, demonstrate antifibrotic effects with 5-HT_2B receptor antagonists, alleviating several key events common for the fibrotic diseases such as myofibroblast differentiation and connective tissue deposition. In this review, we will address the potential role of 5-HT and in particular the 5-HT_2B receptors in three PF-ILDs: ILD associated with systemic sclerosis (SSc-ILD), ILD associated with rheumatoid arthritis (RA-ILD) and IPF. Highlighting the converging pathways in these diseases discloses the 5-HT_2B receptor as a potential disease target for PF-ILDs, which today have an urgent unmet need for therapeutic strategies.

Fibroblast Senescence in Idiopathic Pulmonary Fibrosis

Aging is an inevitable and complex natural phenomenon due to the increase in age. Cellular senescence means a non-proliferative but viable cellular physiological state. It is the basis of aging, and it exists in the body at any time point. Idiopathic pulmonary fibrosis (IPF) is an interstitial fibrous lung disease with unknown etiology, characterized by irreversible destruction of lung structure and function. Aging is one of the most critical risk factors for IPF, and extensive epidemiological data confirms IPF as an aging-related disease. Senescent fibroblasts in IPF show abnormal activation, telomere shortening, metabolic reprogramming, mitochondrial dysfunction, apoptosis resistance, autophagy deficiency, and senescence-associated secretory phenotypes (SASP). These characteristics of senescent fibroblasts establish a close link between cellular senescence and IPF. The treatment of senescence-related molecules and pathways is continually emerging, and using senolytics eliminating senescent fibroblasts is also actively tried as a new therapy for IPF. In this review, we discuss the roles of aging and cellular senescence in IPF. In particular, we summarize the signaling pathways through which senescent fibroblasts influence the occurrence and development of IPF. On this basis, we further talk about the current treatment ideas, hoping this paper can be used as a helpful reference for future researches.

Caveolin-1 scaffolding domain peptide regulates glucose metabolism in lung fibrosis

Increased metabolism distinguishes myofibroblasts or fibrotic lung fibroblasts (fLfs) from the normal lung fibroblasts (nLfs). The mechanism of metabolic activation in fLfs has not been fully elucidated. Furthermore, the antifibrogenic effects of caveolin-1 scaffolding domain peptide CSP/CSP7 involving metabolic reprogramming in fLfs are unclear. We therefore analyzed lactate and succinate levels, as well as the expression of glycolytic enzymes and hypoxia inducible factor-1α (HIF-1α). Lactate and succinate levels, as well as the basal expression of glycolytic enzymes and HIF-1α, were increased in fLfs. These changes were reversed following restoration of p53 or its transcriptional target microRNA-34a (miR-34a) expression in fLfs. Conversely, inhibition of basal p53 or miR-34a increased glucose metabolism, glycolytic enzymes, and HIF-1α in nLfs. Treatment of fLfs or mice having bleomycin- or Ad-TGF-β1-induced lung fibrosis with CSP/CSP7 reduced the expression of glycolytic enzymes and HIF-1α. Furthermore, inhibition of p53 or miR-34a abrogated CSP/CSP7-mediated restoration of glycolytic flux in fLfs in vitro and in mice with pulmonary fibrosis and lacking p53 or miR-34a expression in fibroblasts in vivo. Our data indicate that dysregulation of glucose metabolism in fLfs is causally linked to loss of basal expression of p53 and miR-34a. Treatment with CSP/CSP7 constrains aberrant glucose metabolism through restoration of p53 and miR-34a.

Icariin modulates the sirtuin/NF‑κB pathway and exerts anti‑aging effects in human lung fibroblasts

Icariin (ICA) has been used as a promising anti‑aging drug; however, its underlying molecular mechanism is yet to be elucidated. The present study aimed to determine the anti‑aging molecular mechanisms of ICA. D‑galactose (D‑gal) was used to generate a cell aging model. IMR‑90 human lung fibroblasts were pretreated with different concentrations of ICA (1, 2, 4, 8 and 16 µmol/l) for 6 h and subsequently incubated with D‑gal (200 mmol/l) at 37˚C for 72 h. Senescence of IMR‑90 cells was assessed by senescence‑associated‑β‑galactosidase (SA‑β‑Gal) staining assay. Cell viability, and the expression levels of p53/p21, sirtuin (SIRT) 1/6 and p50/p65 were determined via the MTT assay and western blotting respectively. The results demonstrated that D‑gal notably increased the proportion of SA‑β‑Gal‑positive cells and decreased the viability of IMR‑90 cells; however, pretreatment with ICA reversed the effects of D‑gal on IMR‑90 cells in a concentration‑dependent manner. Furthermore, it was also demonstrated that the activation of p53/p21 and nuclear factor‑κB (NF‑κB) signaling, and downregulation of SIRT1/6 may be involved in IMR‑90 cells, in D‑gal‑induced aging and ICA may effectively prevent IMR‑90 cells from these changes induced by D‑gal. Taken together, the results of the present study suggest that the anti‑aging molecular mechanisms of ICA may be associated with the regulation of the SIRT1/NF‑κB pathway.

Sitagliptin Inhibits Extracellular Matrix Accumulation and Proliferation in Lung Fibroblasts

BACKGROUND Fibroblasts activation-induced fibrosis can cause idiopathic pulmonary fibrosis (IPF). Excessive activation of fibroblasts contributes to poor healing or severe visceral fibrosis and even organ dysfunction. Sitagliptin acts as a dipeptidyl peptidase 4 inhibitor to reduce glucose level in type 2 diabetes, but its role in fibrosis of lung fibroblasts is elusive. We investigated the mechanism of sitagliptin in TGF-ß-activated lung fibroblasts and evaluated the efficacy of sitagliptin in extracellular matrix accumulation and fibroblasts proliferation. MATERIAL AND METHODS By in vitro lung fibroblasts culture, we assessed the expression of lung fibroblasts biomarker (alpha-SMA) and extracellular matrix (Col-1, Col-3, fibronectin) following TGF-ß stimulation and treatment with sitagliptin. Mechanistically, the phosphorylation level of Smad-3 protein in cells was analyzed using Western blotting, and the apoptosis level was assessed by Western blotting and flow cytometry. The degree of proliferation was determined using immunofluorescence and scratch-healing assay. RESULTS We found that treatment with sitagliptin attenuates fibroblasts activation following TGF-ß stimulation. Furthermore, the extracellular matrix was decreased by sitagliptin treatment by suppressing the phosphorylation level of Smad-3 protein. We found that sitagliptin does not affect apoptosis in fibroblasts, but it does affect the degree of proliferation of lung fibroblasts, thus ameliorating fibrosis after TGF-ß stimulation. CONCLUSIONS Sitagliptin inhibits fibrosis in TGF-ß-induced lung fibroblasts activation, which restrains extracellular matrix formation and cell proliferation in fibroblasts. Therefore, sitagliptin appears to have promise as a treatment of fibroproliferative disease caused by activation and proliferation of fibroblasts.

Radiation induced apoptosis and pulmonary fibrosis: curcumin an effective intervention?

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease characterized by interstitial remodeling, leading to compromised lung function. Extra vascular fibrin deposition and abnormalities in the fibrinolysis are the major clinical manifestations of lung diseases such as acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS). ALI progresses to pulmonary fibrosis (PF) and makes patient's life miserable. Anti-fibrinolysis and apoptosis are involved in the progression of PF. Apoptotic markers are detectable within IPF lung tissue and senescent cell deletion can rejuvenate pulmonary health. Enhanced expression of p53 due to DNA damage is seen in irradiated lung tissue. The role of fibrinolytic components such as Urokinase Plasminogen activator (uPA), uPA receptor (uPAR) and Plasminogen activator inhibitor-1 (PAI-1) has been detailed in I. Curcumin is known to possess anti-inflammatory and anti-fibrotic effects. Radioprotective effect of curcumin enables it to attenuate radiation-induced inflammation and fibrosis. Understanding the mechanism of radioprotective effect of curcumin in radiation-induced PF and apoptosis can lead to the development of an effective therapeutic to combat acute lung injury and fibrosis.

Transcriptome sequencing reveals fibrotic associated-genes involved in bovine mammary fibroblasts with Staphylococcus aureus

Bovine mammary fibrosis represents a considerable health problem of cows, primarily indicated by lactation failure. Staphylococcus aureus (S. aureus) can cause mammary damage, this multifactorial disease necessitates to identify how and to what extent molecular pathogen defense mechanisms prevent bacterial infections in bovine mammary gland. In this study, we have aimed to determine the transcriptional responses in bovine mammary fibroblasts (BMFBs) induced by S. aureus using bioinformatics analysis to determine whether mRNA expression profile changes between BMFBs activation and quiescence. Established primary BMFBs obtained from healthy Holstein bovine were induced 10⁶ CFU/mL heat-inactivated S. aureus and total RNA was isolated 6 h after treatment. The 574 DEGs were involved in gene ontology (GO) that were immune response, apoptotic process, extracellular region, receptor binding, endopeptidase activity and protein kinase activity et al. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, distinct pathway contained signaling molecules common to various inflammatory and fibrotic pathways were Pathways in cancer, Cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, TNF signaling pathway, MAPK signaling pathway and Toll-like receptor signaling pathway. The BMFBs was treated with heat-inactivated S. aureus (10⁶ CFU/mL) and also with pharmacological inhibitors of ERK1/2, P38 MAPK and JNK. The MMP-2 activity were examined gelatin zymography, MMP-2, TIMP-1, -2 and PLAU/PAI-1 protein expression were examined in vitro by western blot. The MMP-2 activity was significantly inhibited by simultaneous inhibition of ERK1/2, P38 MAPK and JNK, and MMP-2, TIMP-1,-2 and PLAU/PAI-1 protein expression were significantly decreased by inhibiting ERK1/2, P38 MAPK or JNK. This suggested a crosstalk between the ERK1/2, P38 MAPK or JNK signaling pathways in regulating extracellular matrix metabolism in the BMFBs with S. aureus. Our study complement our initial study on S. aureus-induced responses by fibrosis-associated genes in BMFBs. This may lead to development of novel therapeutic targets to control bovine mammary fibrosis induced by S. aureus.

Acute Lung Injury: IL-17A-Mediated Inflammatory Pathway and Its Regulation by Curcumin

Acute lung injury (ALI) is characterized by acute inflammation and tissue injury results in dysfunction of the alveolar epithelial membrane. If the epithelial injury is severe, a fibroproliferative phase of ALI can develop. During this phase, the activated fibroblast and myofibroblasts synthesize excessive collagenous extracellular matrix that leads to a condition called pulmonary fibrosis. Lung injury can be caused by several ways; however, the present review focus on bleomycin (BLM)-mediated changes in the pathology of lungs. BLM is a chemotherapeutic agent and has toxic effects on lungs, which leads to oxidative damage and elaboration of inflammatory cytokines. In response to the injury, the inflammatory cytokines will be activated to defend the system from injury. These cytokines along with growth factors stimulate the proliferation of myofibroblasts and secretion of pathologic extracellular matrix. During BLM injury, the pro-inflammatory cytokine such as IL-17A will be up-regulated and mediates the inflammation in the alveolar epithelial cell and also brings about recruitment of certain inflammatory cells in the alveolar surface. These cytokines probably help in up-regulating the expression of p53 and fibrinolytic system molecules during the alveolar epithelial cells apoptosis. Here, our key concern is to provide the adequate knowledge about IL-17A-mediated p53 fibrinolytic system and their pathogenic progression to pulmonary fibrosis. The present review focuses mainly on IL-17A-mediated p53-fibrinolytic aspects and how curcumin is involved in the regulation of pathogenic progression of ALI and pulmonary fibrosis.

Telomere length in workers was effected by omethoate exposure and interaction between smoking and p21 polymorphisms

Omethoate is an organophosphorus pesticide that poses a major health hazard, especially DNA damage. The purpose of this study was to investigate the factors affecting telomere length in workers exposed to omethoate by analyzing the interaction between cell cycle gene polymorphism and environmental factors. The exposure group consisted of 118 workers exposed to omethoate for 8-10 years, the control group comprised 115 healthy people without occupational toxicant exposure history. The telomere length of genomic DNA from peripheral blood leucocyte was determined with real-time PCR. Polymerase chain reaction and restriction fragment length polymorphism was used to detect the polymorphisms in p53, p21 and MDM2 gene. The telomere length in the (CA + AA) genotypes for p21 rs1801270 polymorphism was longer than that in the CC genotype in control group (P = 0.015). The generalized linear model analysis indicated the interaction of the p21 rs1801270 polymorphic (CA + AA) genotypes and smoking has a significant effect on telomere length (β = -0.258, P = 0.085). The prolongation of telomere length in omethoate-exposed workers was associated with genotypes (CA + AA) of p21 rs1801270, and interactions of (CA + AA) genotypes and smoking factor.

p53 Expression in Lung Fibroblasts Is Linked to Mitigation of Fibrotic Lung Remodeling

Idiopathic pulmonary fibrosis (IPF) is a debilitating, incurable, and life-threatening disease. A cardinal feature of the pathogenesis of IPF is excessive extracellular matrix deposition attributable to proliferation of activated fibrotic lung fibroblasts (fLfs). To assess the underlying mechanism, we analyzed the status of the tumor suppressor protein p53 in fLfs from the lungs of IPF patients or mice with bleomycin-induced established PF. We report that basal expression of p53 is markedly reduced in fLfs. Forced expression of caveolin-1 in fLfs increased basal p53 and reduced profibrogenic proteins, including collagen-1. Transduction of fLfs with adenovirus expressing p53 reduced expression of these proteins. Conversely, inhibition of baseline p53 in control lung fibroblasts from lung tissues increased profibrogenic protein expression. Lung transduction of adenovirus expressing p53 reduced bleomycin-induced PF in wild-type or caveolin-1-deficient mice. Furthermore, treatment of fLfs or fibrotic lung tissues with caveolin-1 scaffolding domain peptide (CSP) or its fragment, CSP7, restored p53 and reduced profibrogenic proteins. Treatment of wild-type mice with i.p. CSP or CSP7 resolved bleomycin-induced PF. These peptides failed to resolve PF in inducible conditional knockout mice lacking p53 in fLfs, indicating the induction of baseline fLf p53 as the basis of the antifibrotic effects.

Dysregulation of Mesenchymal Cell Survival Pathways in Severe Fibrotic Lung Disease: The Effect of Nintedanib Therapy

Impaired apoptotic clearance of myofibroblasts can result in the continuous expansion of scar tissue during the persistent injury in the lung. However, the molecular and cellular mechanisms underlying the apoptotic clearance of multiple mesenchymal cells including fibrocytes, fibroblasts and myofibroblasts in severe fibrotic lung diseases such as idiopathic pulmonary fibrosis (IPF) remain largely unknown. We analyzed the apoptotic pathways activated in mesenchymal cells of IPF and in a mouse model of TGFα-induced pulmonary fibrosis. We found that fibrocytes and myofibroblasts in fibrotic lung lesions have acquired resistance to Fas-induced apoptosis, and an FDA-approved anti-fibrotic agent, nintedanib, effectively induced apoptotic cell death in both. In support, comparative gene expression analyses suggest that apoptosis-linked gene networks similarly dysregulated in both IPF and a mouse model of TGFα-induced pulmonary fibrosis. TGFα mice treated with nintedanib show increased active caspase 3-positive cells in fibrotic lesions and reduced fibroproliferation and collagen production. Further, the long-term nintedanib therapy attenuated fibrocyte accumulation, collagen deposition, and lung function decline during TGFα-induced pulmonary fibrosis. These results highlight the importance of inhibiting survival pathways and other pro-fibrotic processes in the various types of mesenchymal cells and suggest that the TGFα mouse model is relevant for testing of anti-fibrotic drugs either alone or in combination with nintedanib.

Asymmetric dimethylarginine: An crucial regulator in tissue fibrosis

Fibrosis is a reparative process with very few therapeutic options to prevent its progression to organ dysfunction. Chronic fibrotic diseases contribute to an estimated 45% of all death in the industrialized world. Asymmetric dimethylarginine (ADMA), an endothelial nitric oxide synthase inhibitor, plays a crucial role in the pathogenesis of various cardiovascular diseases associated with endothelial dysfunction. Recent reports have focused on ADMA in the pathogenesis of tissue fibrosis. This review discusses the current knowledge about ADMA biology, its association with risk factors of established fibrotic diseases and the potential pathophysiological mechanisms implicating ADMA in the process of tissue fibrosis.

Secretory Inositol Polyphosphate 4-Phosphatase Protects against Airway Inflammation and Remodeling

The asthma candidate gene inositol polyphosphate 4-phosphatase type I A (INPP4A) is a lipid phosphatase that negatively regulates the PI3K/Akt pathway. Destabilizing genetic variants of INPP4A increase the risk of asthma, and lung-specific INPP4A knockdown induces asthma-like features. INPP4A is known to localize intracellularly, and its extracellular presence has not been reported yet. Here we show for the first time that INPP4A is secreted by airway epithelial cells and that extracellular INPP4A critically inhibits airway inflammation and remodeling. INPP4A was present in blood and BAL fluid, and this extracellular INPP4A was reduced in patients with asthma and mice with allergic airway inflammation. In both naive mice and mice with allergic airway inflammation, antibody-mediated neutralization of extracellular INPP4A potentiated PI3K/Akt signaling and induced airway hyperresponsiveness, with prominent airway remodeling, subepithelial fibroblast proliferation, and collagen deposition. The link between extracellular INPP4A and fibroblasts was investigated in vitro. Cultured airway epithelial cells secreted enzymatically active INPP4A in extracellular vesicles and in a free form. Extracellular vesicle-mediated transfer of labeled INPP4A, from epithelial cells to fibroblasts, was observed. Inhibition of such transfer by anti-INPP4A antibody increased fibroblast proliferation. We propose that secretory INPP4A is a novel "paracrine" layer of the intricate regulation of lung homeostasis, by which airway epithelium dampens PI3K/Akt signaling in inflammatory cells or local fibroblasts, thereby limiting inflammation and remodeling.

Amitriptyline attenuates bleomycin-induced pulmonary fibrosis: modulation of the expression of NF-κβ, iNOS, and Nrf2

Amitriptyline is a tricyclic antidepressant that was suggested to have antifibrotic potential. The current study aimed to investigate the modulatory effects of amitriptyline on bleomycin-induced pulmonary fibrosis in rats. Rats were randomly assigned into 4 groups: normal control, bleomycin control, amitriptyline+bleomycin, and amitriptyline only treated group. Lung injury was evaluated through the histological examination and immunohistochemical detection of α-smooth muscle actin (α-SMA) in lung tissue, in addition to the biochemical assessment of pulmonary contents of hydroxyproline and transforming growth factor beta-1 (TGF-β1). In addition, the following parameters were investigated for studying the possible mechanisms of amitriptyline antifibrotic effect: inducible nitric oxide synthase (iNOS), nuclear factor-κβ (NF-κβ), tumor necrosis factor-alpha (TNF-α), serpine-1, p53, nuclear factor erythroid 2-related factor 2 (Nrf2), lipid peroxides, and reduced glutathione (GSH). Amitriptyline exhibited potent antifibrotic effect that was reflected upon the histopathological examination and through its ability to suppress all the fibrotic parameters. Amitriptyline successfully suppressed the expression of NF-κβ, Nrf2, iNOS, and p53 in lung tissues besides the inhibition of other oxidative stress and inflammatory mediators. Amitriptyline could be a promising treatment to pulmonary fibrosis. Amitriptyline not only prevents the depression and its drawbacks in patients suffering from pulmonary fibrosis but also it can suppress fibrosis through variable mechanisms mainly via inhibition of NF-κβ/TNF-α/TGF-β pathway in addition to inhibition of Nrf2 and iNOS expression.

Inflammatory and Fibrinolytic System in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is the most advanced form of acute lung injury (ALI). This is characterized by bilateral pulmonary infiltrates and severe hypoxemia. According to Berlin definition of ARDS, this is defined based on the timings, radiographic changes, edema formation, and severity on the PaO₂/FiO₂ ratio. During ARDS, the loss of integrity of the epithelium causes the septic shock. The degree of epithelial injury is the major prognostic marker of ARDS. In addition to this, inflammatory cell migration, fibro-proliferation, and activation of apoptosis also play an important role in the pathophysiology of ARDS. The alveolar epithelial cell is the prime target during injury where this cell either undergo apoptosis or epithelial-mesenchymal transition (EMT). Injury to the AECs triggers the changes in the DNA fragmentation and activation of certain apoptotic markers such as caspases at the same time some cells undergo biochemical changes and loses its epithelial morphology as well epithelial biomarkers and gain mesenchymal biomarkers and morphology. In both the cases, the fibrinolytic system plays an important role in maintaining the integrity of the disease process efficiently. This review highlights the research evidence of apoptosis and EMT in lung development, injury and its prognosis in ARDS thereby to develop an effective strategy for the treatment of ARDS.

Curcumin down-regulates IL-17A mediated p53-fibrinolytic system in bleomycin induced acute lung injury in vivo

Bleomycin (BLM) induced cellular damage causes inflammation in the alveolar compartment and impairment of fibrinolytic system leads to alveolar epithelial cell apoptosis. Here, we describe novel inflammatory pathway associated with p53-fibrinolytic system and apoptosis of alveolar epithelial cells and pharmacological efficiency of curcumin against this action. In the present study we used C57BL/6 mice. The specific dose and time interval of curcumin were analyzed to assess the intervention. Experiments were designed to investigate the IL-17A mediated modulation in the alveolar epithelial cell apoptosis and injury. Various techniques such as Western blot, RT-PCR, Immunohistochemistry were used for this study. We observed that the BLM-induced lung injury and its progression were successfully regulated by the effective dose and time intervention of curcumin. There was also decreased expression of chemokines, p53, and fibrinolytic components such as PAI-1 and increased uPA, uPAR expression, and decreased alveolar epithelial cell apoptosis, which indicates the IL-17A mediated novel inflammatory pathway. It is confirmed that the IL-17A involved in the modulation of p53-fibrinolytic system and epithelial cell apoptosis in BLM induced mice. The cross-talk between the inflammatory, fibrinolytic, and apoptotic pathways were resolved by curcumin intervention. This pathway and intervention could serve as a modern therapy to resolve the complications to cure the lung injury and its progression.

The fibrogenic actions of the coagulant and plasminogen activation systems in pulmonary fibrosis

Fibrosis causes irreversible damage to lung structure and function in restrictive lung diseases such as idiopathic pulmonary fibrosis (IPF). Extravascular coagulation involving fibrin formation in the intra-alveolar compartment is postulated to have a pivotal role in the development of pulmonary fibrosis, serving as a provisional matrix for migrating fibroblasts. Furthermore, proteases of the coagulation and plasminogen activation (plasminergic) systems that form and breakdown fibrin respectively directly contribute to pulmonary fibrosis. The coagulants, thrombin and factor Xa (FXa) evoke fibrogenic effects via cleavage of the N-terminus of protease-activated receptors (PARs). Whilst the formation and activity of plasmin, the principle plasminergic mediator is suppressed in the airspaces of patients with IPF, localized increases are likely to occur in the lung interstitium. Plasmin-evoked proteolytic activation of factor XII (FXII), matrix metalloproteases (MMPs) and latent, matrix-bound growth factors such as epidermal growth factor (EGF) indirectly implicate plasmin in pulmonary fibrosis. Another plasminergic protease, urokinase plasminogen activator (uPA) is associated with regions of fibrosis in the remodelled lung of IPF patients and elicits fibrogenic activity via binding its receptor (uPAR). Plasminogen activator inhibitor-1 (PAI-1) formed in the injured alveolar epithelium also contributes to pulmonary fibrosis in a manner that involves vitronectin binding. This review describes the mechanisms by which components of the two systems primarily involved in fibrin homeostasis contribute to interstitial fibrosis, with a particular focus on IPF. Selectively targeting the receptor-mediated mechanisms of coagulant and plasminergic proteases may limit pulmonary fibrosis, without the bleeding complications associated with conventional anti-coagulant and thrombolytic therapies.

Safer approaches to therapeutic modulation of TGF-β signaling for respiratory disease

The transforming growth factor (TGF)-β cytokines play a central role in development and progression of chronic respiratory diseases. TGF-β overexpression in chronic inflammation, remodeling, fibrotic process and susceptibility to viral infection is established in the most prevalent chronic respiratory diseases including asthma, COPD, lung cancer and idiopathic pulmonary fibrosis. Despite the overwhelming burden of respiratory diseases in the world, new pharmacological therapies have been limited in impact. Although TGF-β inhibition as a therapeutic strategy carries great expectations, the constraints in avoiding compromising the beneficial pleiotropic effects of TGF-β, including the anti-proliferative and immune suppressive effects, have limited the development of effective pharmacological modulators. In this review, we focus on the pathways subserving deleterious and beneficial TGF-β effects to identify strategies for selective modulation of more distal signaling pathways that may result in agents with improved safety/efficacy profiles. Adverse effects of TGF-β inhibitors in respiratory clinical trials are comprehensively reviewed, including those of the marketed TGF-β modulators, pirfenidone and nintedanib. Precise modulation of TGF-β signaling may result in new safer therapies for chronic respiratory diseases.

Formulation for a novel inhaled peptide therapeutic for idiopathic pulmonary fibrosis

A caveolin-1 scaffolding domain, CSP7, is a newly developed peptide for the treatment of idiopathic pulmonary fibrosis. To develop a CSP7 formulation for further use we have obtained, characterized and compared a number of lyophilized formulations of CSP7 trifluoroacetate with DPBS and in combination with excipients (mannitol and lactose at molar ratios 1:5, 70 and 140). CSP7 trifluoroacetate was stable (>95%) in solution at 5 and 25 °C for up to 48 h and tolerated at least 5 freeze/thaw cycles. Lyophilized cakes of CSP7 trifluoroacetate with excipients were stable (>96%) for up to 4 weeks at room temperature (RT), and retained more than 98% of the CSP7 trifluoroacetate in the solution at 8 h after reconstitution at RT. The lyophilized CSP7 formulations were stable for up to 10 months at 5 °C protected from moisture. Exposure of the lyophilized cakes of CSP7 to 75% relative humidity (RH) resulted in an increase in the absorbed moisture, promoted crystallization of the excipients and induced reversible formation of CSP7 aggregates. Increased molar ratio of mannitol slightly affected formation of the aggregates. In contrast, lactose significantly decreased (up to 20 times) aggregate formation with apparent saturation at the molar ratio of 1:70. The possible mechanisms of stabilization of CSP7 trifluoroacetate in solid state by lactose include physical state of the bulking agent and the interactions between lactose and CSP7 trifluoroacetate (e.g. formation of a Schiff base with the N-terminal amino group of CSP7). Finally, CSP7 trifluoroacetate exhibited excellent stability during nebulization of formulations containing mannitol or lactose.

Serpine 1 induces alveolar type II cell senescence through activating p53-p21-Rb pathway in fibrotic lung disease

Senescence of alveolar type 2 (ATII) cells, progenitors of the alveolar epithelium, is implicated in the pathogeneses of idiopathic pulmonary fibrosis (IPF), an aging‐related progressive fatal lung disorder with unknown etiology. The mechanism underlying ATII cell senescence in fibrotic lung diseases, however, remains poorly understood. In this study, we report that ATII cells in IPF lungs express higher levels of serpine 1, also known as plasminogen activator inhibitor 1 (PAI‐1), and cell senescence markers p21 and p16, compared to ATII cells in control lungs. Silencing PAI‐1 or inhibition of PAI‐1 activity in cultured rat ATII (L2) cells leads to decreases in p53 serine 18 phosphorylation (p53^S18P), p53 and p21 protein expressions; an increase in retinoblastoma protein phosphorylation (ppRb); and a reduction in the sensitivity to bleomycin‐ and doxorubicin‐induced senescence. Silencing p53, on the other hand, abrogates PAI‐1 protein‐stimulated p21 expression and cell senescence. In vivo studies, using ATII cell‐specific PAI‐1 conditional knockout mouse model generated recently in this laboratory, further support the role of PAI‐1 in the activation of p53‐p21‐Rb cell cycle repression pathway, ATII cell senescence, and lung fibrosis induced by bleomycin. This study reveals a novel function of PAI‐1 in regulation of cell cycle and suggests that elevation of PAI‐1 contributes importantly to ATII cell senescence in fibrotic lung diseases.

Precision-guided, Personalized Intrapleural Fibrinolytic Therapy for Empyema and Complicated Parapneumonic Pleural Effusions: The Case for the Fibrinolytic Potential

Complicated pleural effusions and empyema with loculation and failed drainage are common clinical problems. In adults, intrapleural fibrinolytic therapy is commonly used with variable results and therapy remains empiric. Despite the intrapleural use of various plasminogen activators; fibrinolysins, for about sixty years, there is no clear consensus about which agent is most effective. Emerging evidence demonstrates that intrapleural administration of plasminogen activators is subject to rapid inhibition by plasminogen activator inhibitor-1 and that processing of fibrinolysins is importantly influenced by other factors including the levels and quality of pleural fluid DNA. Current therapy for loculation that accompanies pleural infections also includes surgery, which is invasive and for which patient selection can be problematic. Most of the clinical literature published to date has used flat dosing of intrapleural fibrinolytic therapy in all subjects but little is known about how that strategy influences the processing of the administered fibrinolysin or how this influences outcomes. We developed a new test of pleural fluids ex vivo, which is called the Fibrinolytic Potential or FP, in which a dose of a fibrinolysin is added to pleural fluids ex vivo after which the fibrinolytic activity is measured and normalized to baseline levels. Testing in preclinical and clinical empyema fluids reveals a wide range of responses, indicating that individual patients will likely respond differently to flat dosing of fibrinolysins. The test remains under development but is envisioned as a guide for dosing of these agents, representing a novel candidate approach to personalization of intrapleural fibrinolytic therapy.

Regulation of p53-mediated changes in the uPA-fibrinolytic system and in lung injury by loss of surfactant protein C expression in alveolar epithelial cells

Pulmonary surfactant protein C (SP-C) expression by type II alveolar epithelial cells (AECs) is markedly reduced in diverse types of lung injuries and is often associated with AEC apoptosis. It is unclear whether loss of SP-C contributes to the increased p53 and urokinase-type plasminogen activator (uPA) system cross-talk and apoptosis of AECs. Therefore, we inhibited SP-C expression in human and murine AECs using lentivirus vector expressing shRNA and tested p53 and downstream changes in the uPA-fibrinolytic system. Inhibition of SP-C expression in AECs induced p53 and activated caspase-3, indicating AEC apoptosis. We also found that bleomycin or cigarette smoke exposure failed to inhibit SP-C expression or apoptosis in AECs in p53- and plasminogen activator inhibitor-1 (PAI-1)-deficient mice. Depletion of SP-C expression by lentiviral SP-C shRNA in PAI-1-deficient mice failed to induce p53 or apoptosis in AECs, whereas it increased both AEC p53 and apoptosis in wild-type and uPA-deficient mice. SP-C inhibition in AECs also increased in CXCL1 and CXCL2 and their receptor CXCR2 as well as ICAM-1 expression, which is indicative of a proinflammatory response. Overexpression of p53-binding 3'-UTR sequences in AECs inhibited PAI-1 induction while maintaining uPA and uPAR protein and mRNA expression. Furthermore, caveolin-1 expression and phosphorylation were increased in AECs, indicating an intricate link between caveolin-1 and Src kinase-mediated cell signaling and AEC apoptosis due to loss of SP-C expression through p53 and uPA system-mediated cross-talk. The role of uPA, PAI-1, and p53 in the regulation of AEC apoptosis after injury was also determined in knockout mice.

p53 and miR-34a Feedback Promotes Lung Epithelial Injury and Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease. The pathogenesis of interstitial lung diseases, including its most common form, IPF, remains poorly understood. Alveolar epithelial cell (AEC) apoptosis, proliferation, and accumulation of myofibroblasts and extracellular matrix deposition results in progressive loss of lung function in IPF. We found induction of tumor suppressor protein, p53, and apoptosis with suppression of urokinase-type plasminogen activator (uPA) and the uPA receptor in AECs from the lungs of IPF patients, and in mice with bleomycin, cigarette smoke, silica, or sepsis-induced lung injury. Treatment with the caveolin-1 scaffolding domain peptide (CSP) reversed these effects. Consistent with induction of p53, AECs from IPF lungs or mice with diverse types of lung injuries showed increased p53 acetylation and miR-34a expression with reduction in Sirt1. This was significantly reduced after treatment of wild-type mice with CSP, and uPA-deficient mice were unresponsive. Bleomycin failed to induce miR-34a in p53- or plasminogen activator inhibitor-1 (PAI-1)-deficient mice. CSP-mediated inhibition of miR-34a restored Sirt1, suppressed p53 acetylation and apoptosis in injured AECs, and prevented pulmonary fibrosis (PF). AEC-specific suppression of miR-34a inhibited bleomycin-induced p53, PAI-1, and apoptosis and prevented PF, whereas overexpression of precursor-miR-34a increased p53, PAI-1, and apoptosis in AECs of mice unexposed to bleomycin. Our study validates p53-miR-34a feedback as a potential therapeutic target in PF.

The fibrogenic actions of lung fibroblast-derived urokinase: a potential drug target in IPF

The role of urokinase plasminogen activator (uPA) in idiopathic pulmonary fibrosis (IPF) remains unclear. uPA-generated plasmin has potent fibrogenic actions involving protease activated receptor-1 (PAR-1) and interleukin-6 (IL-6). Here we characterize uPA distribution or levels in lung tissue and sera from IPF patients to establish the mechanism of its fibrogenic actions on lung fibroblasts (LFs). uPA immunoreactivity was detected in regions of fibrosis including fibroblasts of lung tissue from IPF patients (n = 7). Serum uPA levels and activity were also higher in IPF patients (n = 18) than controls (n = 18) (P < 0.05), being negatively correlated with lung function as measured by forced vital capacity (FVC) %predicted (P < 0.05). The culture supernatants of LFs from IPF patients, as compared to controls, showed an increase in plasmin activity after plasminogen incubation (5–15 μg/mL), corresponding with increased levels of uPA and IL-6 (n = 5–6, P < 0.05). Plasminogen-induced increases in plasmin activity and IL-6 levels were attenuated by reducing uPA and/or PAR-1 expression by RNAi. Plasmin(ogen)-induced mitogenesis was also attenuated by targeting uPA, PAR-1 or IL-6. Our data shows uPA is formed in active regions of fibrosis in IPF lung and contributes to LF plasmin generation, IL-6 production and proliferation. Urokinase is a potential target for the treatment of lung fibrosis.

iTRAQ-Based Proteomics Reveals Novel Biomarkers for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a gradual lung disease with a survival of less than 5 years post-diagnosis for most patients. Poor molecular description of IPF has led to unsatisfactory interpretation of the pathogenesis of this disease, resulting in the lack of successful treatments. The objective of this study was to discover novel noninvasive biomarkers for the diagnosis of IPF. We employed a coupled isobaric tag for relative and absolute quantitation (iTRAQ)-liquid chromatography–tandem mass spectrometry (LC–MS/MS) approach to examine protein expression in patients with IPF. A total of 97 differentially expressed proteins (38 upregulated proteins and 59 downregulated proteins) were identified in the serum of IPF patients. Using String software, a regulatory network containing 87 nodes and 244 edges was built, and the functional enrichment showed that differentially expressed proteins were predominantly involved in protein activation cascade, regulation of response to wounding and extracellular components. A set of three most significantly upregulated proteins (HBB, CRP and SERPINA1) and four most significantly downregulated proteins (APOA2, AHSG, KNG1 and AMBP) were selected for validation in an independent cohort of IPF and other lung diseases using ELISA test. The results confirmed the iTRAQ profiling results and AHSG, AMBP, CRP and KNG1 were found as specific IPF biomarkers. ROC analysis indicated the diagnosis potential of the validated biomarkers. The findings of this study will contribute in understanding the pathogenesis of IPF and facilitate the development of therapeutic targets.

The vitronectin RGD motif regulates TGF-β-induced alveolar epithelial cell apoptosis

Transforming growth factor-β (TGF-β) is a critical driver of acute lung injury and fibrosis. Injury leads to activation of TGF-β, which regulates changes in the cellular and matrix makeup of the lung during the repair and fibrosis phase. TGF-β can also initiate alveolar epithelial cell (AEC) apoptosis. Injury leads to destruction of the laminin-rich basement membrane, which is replaced by a provisional matrix composed of arginine-glycine-aspartate (RGD) motif-containing plasma matrix proteins, including vitronectin and fibronectin. To determine the role of specific matrix proteins on TGF-β-induced apoptosis, we studied primary AECs cultured on different matrix conditions and utilized mice with deletion of vitronectin (Vtn(-/-)) or mice in which the vitronectin RGD motif is mutated to nonintegrin-binding arginine-glycine-glutamate (RGE) (Vtn(RGE/RGE)). We found that AECs cultured on fibronectin and vitronectin or in wild-type mouse serum are resistant to TGF-β-induced apoptosis. In contrast, AECs cultured on laminin or in serum from Vtn(-/-) or Vtn(RGE/RGE) mice undergo robust TGF-β-induced apoptosis. Plasminogen activator inhibitor-1 (PAI-1) sensitizes AECs to greater apoptosis by disrupting AEC engagement to vitronectin. Inhibition of integrin-associated signaling proteins augments AEC apoptosis. Mice with transgenic deletion of PAI-1 have less apoptosis after bleomycin, but deletion of vitronectin or disruption of the vitronectin RGD motif reverses this protection, suggesting that the proapoptotic function of PAI-1 is mediated through vitronectin inhibition. Collectively, these data suggest that integrin-matrix signaling is an important regulator of TGF-β-mediated AEC apoptosis and that PAI-1 functions as a natural regulator of this interaction.

The Role of Mitochondrial DNA in Mediating Alveolar Epithelial Cell Apoptosis and Pulmonary Fibrosis

Convincing evidence has emerged demonstrating that impairment of mitochondrial function is critically important in regulating alveolar epithelial cell (AEC) programmed cell death (apoptosis) that may contribute to aging-related lung diseases, such as idiopathic pulmonary fibrosis (IPF) and asbestosis (pulmonary fibrosis following asbestos exposure). The mammalian mitochondrial DNA (mtDNA) encodes for 13 proteins, including several essential for oxidative phosphorylation. We review the evidence implicating that oxidative stress-induced mtDNA damage promotes AEC apoptosis and pulmonary fibrosis. We focus on the emerging role for AEC mtDNA damage repair by 8-oxoguanine DNA glycosylase (OGG1) and mitochondrial aconitase (ACO-2) in maintaining mtDNA integrity which is important in preventing AEC apoptosis and asbestos-induced pulmonary fibrosis in a murine model. We then review recent studies linking the sirtuin (SIRT) family members, especially SIRT3, to mitochondrial integrity and mtDNA damage repair and aging. We present a conceptual model of how SIRTs modulate reactive oxygen species (ROS)-driven mitochondrial metabolism that may be important for their tumor suppressor function. The emerging insights into the pathobiology underlying AEC mtDNA damage and apoptosis is suggesting novel therapeutic targets that may prove useful for the management of age-related diseases, including pulmonary fibrosis and lung cancer.

Regulation of Gene Expression by Sodium Valproate in Epithelial-to-Mesenchymal Transition

PURPOSE

Epithelial-to-mesenchymal transition (EMT) is an important mechanism in cancer metastasis and pulmonary fibrosis. Previous studies demonstrated effect of histone H3 and H4 acetylation in cancer and pulmonary fibrosis, so we hypothesized that histone modification might play a crucial role in gene regulation during EMT. In this study, we investigated the mechanism behind EMT by analyzing comprehensive gene expression and the effect of sodium valproate (VPA), a class I histone deacetylase inhibitory drug, on histone modification.

METHODS

EMT was induced in human alveolar epithelial cells (A549) using 5 ng/mL of transforming growth factor (TGF)-β1. Various concentrations of VPA were then administered, and Western blotting was used to analyze histone acetylation or methylation. Comprehensive gene expression analysis was carried out by RNA sequencing, and chromatin immunoprecipitation was performed with an anti-acetyl histone H3 lysine 27 antibody.

RESULTS

TGF-β1 stimulation led to a decrease in histone acetylation, especially that of histone H3K27, and H3K27ac localization was decreased at particular gene loci. This decrease was recovered by VPA treatment, which also up-regulated the mRNA expression of genes down-regulated by TGF-β1, and correlated with the localization of H3K27ac. However, genes up-regulated by TGF-β1 stimulation were not suppressed by VPA, with the exception of COL1A1.

CONCLUSIONS

Histone acetylation was down-regulated by TGF-β1 stimulation in A549 cells. VPA partially inhibited EMT and the decrease of histone acetylation, which plays an important role in the progression of EMT.

Enhanced chemokine-receptor expression, function, and signaling in healthy African American and scleroderma-patient monocytes are regulated by caveolin-1

Background

A major health disparity suffered by African Americans (AA) is a predisposition toward fibrotic diseases of the skin, lung, and other organs. We previously showed that healthy AA and scleroderma (systemic sclerosis (SSc)) patient monocytes share biochemical and functional differences from control Caucasian (C) monocytes that may predispose AA to SSc. The central difference is a decrease in caveolin-1. Low caveolin-1 levels promote monocyte migration, their differentiation into fibrocytes, and fibrocyte recruitment into fibrotic tissues. Here we have greatly expanded our studies on the mechanism of action in fibrosis of caveolin-1 in AA and SSc monocytes.

Results

Expression of chemokine receptors (CCR1, CCR2, CCR3) is enhanced in healthy AA monocytes compared to healthy C monocytes and further increased in SSc monocytes. A parallel increase in function occurs assessed by migration toward chemokines MCP-1 and MCP-3. Chemokine-receptor expression and function are inhibited by the caveolin-1 scaffolding domain peptide (CSD) via its action as a surrogate for caveolin-1. Cells bearing chemokine receptors accumulate to high levels in fibrotic lung and skin tissue from SSc patients and from mice treated with bleomycin. This accumulation is almost completely blocked in mice treated with CSD. In signaling studies, Src activation is enhanced in AA monocytes compared to C monocytes and further increased in SSc monocytes. Lyn is also highly activated in SSc monocytes. Src and Lyn activation are inhibited by CSD. Src and Lyn’s roles in monocyte migration were demonstrated using specific inhibitors.

Conclusions

To the best of our knowledge, this is the first report that the expression and function of CCR1, CCR2, and CCR3 are upregulated in monocytes from healthy AA and from SSc patients via molecular mechanisms involving caveolin-1, Src/Lyn, and MEK/ERK. The results suggest that the migration/recruitment of monocytes and fibrocytes into fibrotic tissues, mediated at least in part by CCR1, CCR2, and CCR3, plays a major role in the progression of lung and skin fibrosis and in the predisposition of AA to fibrotic diseases. Our findings further suggest that chemokine receptors and signaling molecules, particularly caveolin-1, that control their expression/function are promising targets for treating fibrotic diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13069-015-0028-7) contains supplementary material, which is available to authorized users.