Matrix metalloproteinases promote inflammation and fibrosis in asbestos-induced lung injury in mice

Repeated Silica exposures lead to Silicosis severity via PINK1/PARKIN mediated mitochondrial dysfunction in mice model

BACKGROUND AND OBJECTIVES

Silicosis, one of the occupational health illnesses is caused by inhalation of crystalline silica. Deposition of extracellular matrix and fibroblast proliferation in lungs are linked to silicosis development. Mitochondrial dysfunction plays critical role in some diseases, but how these processes progress and regulated in silicosis, remains limited. Detailed study of silica induced pulmonary fibrosis in mouse model, its progression and severity may be helpful in designing future therapeutic strategies.

METHODS

In present study, mice model of silicosis has been developed after repeated silica exposures which may closely resemble clinical symptoms of silicosis in human. In addition to efficiently mimicking the acute/chronic transformation processes of silicosis, this is practical and efficient in terms of time and output, which avoids mechanical injury to the upper respiratory tract due to surgical interventions. Sonicated sterile silica suspension (120 mg/kg) was administered through intranasal route thrice a week at regular intervals (21, 28 and 35 days).

RESULTS

Presence of minute to larger silicotic nodules in H&E-stained lung sections were observed in all silica induced model groups. Enhanced ECM deposition was noted in MT stained lung sections of silica exposure groups as compared to control which were confirmed by significantly higher MMP9 expression levels and hydroxyproline content in silica 35 days group. Increase in Reactive oxygen species (ROS), inflammatory cell recruitment mainly, neutrophils and macrophage were observed in all three silica exposure groups. Transmission electron microscopic analysis has confirmed presence of many aberrant shaped mitochondria (swollen, round shape) in 35 days model where autophagosomes were minimum. Western blot analysis of mitophagy and autophagy markers such as Pink1, Parkin, Cytochrome c, SQSTM1/p62, the ratio of light chain LC3B II/LC3B I was found higher in 21 and 28 days which were significantly reduced in 35 days silica model.

CONCLUSIONS

Higher MMP9 activity and MMP9 /TIMP1 ratio demonstrate excessive extracellular matrix damage and deposition in 35 days model. Significantly reduced expressions of autophagy and mitophagy markers have also confirmed progression in fibrosis severity and its association with repeated silica exposures in 35 days model group.

Macrophage-derived MMP12 promotes fibrosis through sustained damage to endothelial cells

Macrophages are essential for the maintenance of endothelial cell function. However, the potential impact and mechanisms of crosstalk between macrophages and endothelial cells during silicosis progression remain unexplored. To fill this knowledge gap, a mouse model of silicosis was established. Single cell sequencing, spatial transcriptome sequencing, western blotting, immunofluorescence staining, tube-forming and wound healing assays were used to explore the effects of silicon dioxide on macrophage-endothelial interactions. To investigate the mechanism of macrophage-mediated fibrosis, MMP12 was specifically inactivated using siRNA and pharmacological approaches, and macrophages were depleted using disodium chlorophosphite liposomes. Compared to the normal saline group, the silica dust group showed altered macrophage-endothelial interactions. Matrix metalloproteinase family member MMP12 was identified as a key mediator of the altered function of macrophage-endothelial interactions after silica exposure, which was accompanied by pro-inflammatory macrophage activation and fibrotic progression. By using ablation strategies, macrophage-derived MMP12 was shown to mediate endothelial cell dysfunction by accumulating on the extracellular matrix. During the inflammatory phase of silicosis, MMP12 secreted by pro-inflammatory macrophages caused decreased endothelial cell viability, reduced migration, decreased trans-endothelial resistance and increased permeability; while during the fibrotic phase, macrophage-derived MMP12 sustained endothelial cell injury through accumulation on the extracellular matrix.

The endothelium in lung fibrosis: a core signaling hub in disease pathogenesis?

Pulmonary fibrosis (PF) is a progressive chronic lung disease characterized by excessive deposition of extracellular matrix (ECM) and structural destruction, associated with a severe 5-year mortality rate. The onset of the disease is thought to be triggered by chronic damage to the alveolar epithelium. Since the pulmonary endothelium is an important component of the alveolar-capillary niche, it is also affected by the initial injury. In addition to ensuring proper gas exchange, the endothelium has critical functional properties, including regulation of vascular tone, inflammatory responses, coagulation, and maintenance of vascular homeostasis and integrity. Recent single-cell analyses have shown that shifts in endothelial cell (EC) subtypes occur in PF. Furthermore, the increased vascular remodeling associated with PF leads to deteriorated outcomes for patients, underscoring the importance of the vascular bed in PF. To date, the causes and consequences of endothelial and vascular involvement in lung fibrosis are poorly understood. Therefore, it is of great importance to investigate the involvement of EC and the vascular system in the pathogenesis of the disease. In this review, we will outline the current knowledge on the role of the pulmonary vasculature in PF, in terms of abnormal cellular interactions, hyperinflammation, vascular barrier disorders, and an altered basement membrane composition. Finally, we will summarize recent advances in extensive therapeutic research and discuss the significant value of novel therapies targeting the endothelium.

Exposure to Sodium Hypochlorite or Cigarette Smoke Induces Lung Injury and Mechanical Impairment in Wistar Rats

Pulmonary irritants, such as cigarette smoke (CS) and sodium hypochlorite (NaClO), are associated to pulmonary diseases in cleaning workers. We examined whether their association affects lung mechanics and inflammation in Wistar rats. Exposure to these irritants alone induced alterations in the lung mechanics, inflammation, and remodeling. The CS increased airway cell infiltration, acid mucus production, MMP-12 expression, and alveolar enlargement. NaClO increased the number of eosinophils and macrophages in the bronchoalveolar lavage fluid, with cells expressing IL-13, MMP-12, MMP-9, TIMP-1, and iNOS in addition to increased IL-1β and TNF-α levels. Co-exposure to both irritants increased epithelial and smooth muscle cell area, acid mucus production, and IL-13 expression in the airways, while it reduced the lung inflammation. In conclusion, the co-exposure of CS with NaClO reduced the pulmonary inflammation, but increased the acidity of mucus, which may protect lungs from more injury. A cross-resistance in people exposed to multiple lung irritants should also be considered.

Changes to gut amino acid transporters and microbiome associated with increased E/I ratio in Chd8+/- mouse model of ASD-like behavior

Autism spectrum disorder (ASD), a group of neurodevelopmental disorders characterized by social communication deficits and stereotyped behaviors, may be associated with changes to the gut microbiota. However, how gut commensal bacteria modulate brain function in ASD remains unclear. Here, we used chromodomain helicase DNA-binding protein 8 (CHD8) haploinsufficient mice as a model of ASD to elucidate the pathways through which the host and gut microbiota interact with each other. We found that increased levels of amino acid transporters in the intestines of the mouse model of ASD contribute to the high level of serum glutamine and the increased excitation/inhibition (E/I) ratio in the brain. In addition, elevated α-defensin levels in the haploinsufficient mice resulted in dysregulation of the gut microbiota characterized by a reduced abundance of Bacteroides. Furthermore, supplementation with Bacteroides uniformis improved the ASD-like behaviors and restored the E/I ratio in the brain by decreasing intestinal amino acid transport and the serum glutamine levels. Our study demonstrates associations between changes in the gut microbiota and amino acid transporters, and ASD-like behavioral and electrophysiology phenotypes, in a mouse model.

The gut microbiota has been shown to modulate the neural function via the microbiota-gut-brain axis. Here, the authors show that Bacteroides uniformis, a gut commensal bacterium, restores the ASD-like phenotypes by reducing intestinal amino acid transport in an ASD mouse model.

Mechanotransduction in fibrosis: Mechanisms and treatment targets

To perceive and integrate the environmental cues, cells and tissues sense and interpret various physical forces like shear, tensile, and compression stress. Mechanotransduction involves the sensing and translation of mechanical forces into biochemical and mechanical signals to guide cell fate and achieve tissue homeostasis. Disruption of this mechanical homeostasis by tissue injury elicits multiple cellular responses leading to pathological matrix deposition and tissue stiffening, and consequent evolution toward pro-inflammatory/pro-fibrotic phenotypes, leading to tissue/organ fibrosis. This review focuses on the molecular mechanisms linking mechanotransduction to fibrosis and uncovers the potential therapeutic targets to halt or resolve fibrosis.

Conditions Mimicking the Cancer Microenvironment Modulate the Functional Outcome of Human Chorionic Villus Mesenchymal Stem/Stromal Cells in vitro

Mesenchymal stem/stromal cells isolated from chorionic villi of human term placentae (CV-MSCs) possess unique biological characters. They exhibit self-renewal, directional migration, differentiation, and immunomodulatory effects on other cell lineages, by virtue of which they can be utilized as therapeutic carriers, for drug targeting, and therapy. Tumors display characteristic features of a damaged tissue microenvironment, which is saturated with conditions such as hypoxia, sustained inflammation, and increased oxidative stress. CV-MSCs function normally in a high oxidative stress environment induced by hydrogen peroxide (H₂O₂) and glucose and also protect endothelial cells from their damaging effects. For their therapeutic applications in a disease like cancer, it is necessary to ascertain the effects of tumor microenvironment on their functional outcome. In this study, we investigated the functional activities, of CV-MSCs in response to conditioned media (CM) obtained from the culture of breast cancer cell line MDA-231 (CM-MDA231). CV-MSCs were exposed to CM-MDA231 for different spatio-temporal conditions, and their biological functions as well as modulation in gene expression were evaluated. Effect of CM-MDA231 on factors responsible for changes in functional outcome were also investigated at the protein levels. CV-MSCs exhibited significant reduction in proliferation but increased adhesion and migration after CM-MDA231 treatment. Interestingly, there was no change in their invasion potential. CM-MDA231 treatment modulated expression of various genes involved in important cellular events including, integration, survival, message delivery and favorable outcome after transplantation. Analysis of pathways related to cell cycle regulation revealed significant changes in the expression of p53, and increased phosphorylation of Retinoblastoma (Rb) and Checkpoint Kinase 2 in CV-MSCs treated with CM-MDA231. To summarize, these data reveal that CV-MSCs retain the ability to survive, adhere, and migrate after sustained treatment with CM-MDA231, a medium that mimics the cancer microenvironment. These properties of CV-MSCs to withstand the inflammatory tumor like microenvironment prove that they may make useful candidate in a stem cell based therapy against cancer. However, further pre-clinical studies are needed to validate their therapeutic usage.

Repeated Administration of Clinically Relevant Doses of the Prescription Opioids Tramadol and Tapentadol Causes Lung, Cardiac, and Brain Toxicity in Wistar Rats

Tramadol and tapentadol, two structurally related synthetic opioid analgesics, are widely prescribed due to the enhanced therapeutic profiles resulting from the synergistic combination between μ-opioid receptor (MOR) activation and monoamine reuptake inhibition. However, the number of adverse reactions has been growing along with their increasing use and misuse. The potential toxicological mechanisms for these drugs are not completely understood, especially for tapentadol, owing to its shorter market history. Therefore, in the present study, we aimed to comparatively assess the putative lung, cardiac, and brain cortex toxicological damage elicited by the repeated exposure to therapeutic doses of both prescription opioids. To this purpose, male Wistar rats were intraperitoneally injected with single daily doses of 10, 25, and 50 mg/kg tramadol or tapentadol, corresponding to a standard analgesic dose, an intermediate dose, and the maximum recommended daily dose, respectively, for 14 consecutive days. Such treatment was found to lead mainly to lipid peroxidation and inflammation in lung and brain cortex tissues, as shown through augmented thiobarbituric acid reactive substances (TBARS), as well as to increased serum inflammation biomarkers, such as C reactive protein (CRP) and tumor necrosis factor-α (TNF-α). Cardiomyocyte integrity was also shown to be affected, since both opioids incremented serum lactate dehydrogenase (LDH) and α-hydroxybutyrate dehydrogenase (α-HBDH) activities, while tapentadol was associated with increased serum creatine kinase muscle brain (CK-MB) isoform activity. In turn, the analysis of metabolic parameters in brain cortex tissue revealed increased lactate concentration upon exposure to both drugs, as well as augmented LDH and creatine kinase (CK) activities following tapentadol treatment. In addition, pneumo- and cardiotoxicity biomarkers were quantified at the gene level, while neurotoxicity biomarkers were quantified both at the gene and protein levels; changes in their expression correlate with the oxidative stress, inflammatory, metabolic, and histopathological changes that were detected. Hematoxylin and eosin (H & E) staining revealed several histopathological alterations, including alveolar collapse and destruction in lung sections, inflammatory infiltrates, altered cardiomyocytes and loss of striation in heart sections, degenerated neurons, and accumulation of glial and microglial cells in brain cortex sections. In turn, Masson's trichrome staining confirmed fibrous tissue deposition in cardiac tissue. Taken as a whole, these results show that the repeated administration of both prescription opioids extends the dose range for which toxicological injury is observed to lower therapeutic doses. They also reinforce previous assumptions that tramadol and tapentadol are not devoid of toxicological risk even at clinical doses.

Expression of Matrix Metalloproteinase-2, Matrix Metalloproteinase-9, Tissue Inhibitor of Metalloproteinase-1, and Changes in Alveolar Septa in Patients with Chronic Obstructive Pulmonary Disease

Background

This study investigated the relationship between the pathological alteration of alveolar septa and (1) pulmonary function and (2) matrix metalloproteinase (MMP)-2, MMP-9, and tissue inhibitor matrix metalloproteinase 1 (TIMP-1) expression in chronic obstructive pulmonary disease (COPD).

Material/Methods

Sixty patients with pulmonary disease were divided into control (n=20) and COPD (n=40) groups. Postoperative lung tissue specimens were examined. Hematoxylin and eosin and elastin van Gieson staining detected pathological alterations of pulmonary alveolar septa. Septa thickness was measured. MMP-2, MMP-9, and TIMP-1 expression levels were detected by immunohistochemical staining. Correlations were determined by Pearson analysis.

Results

Forced expiratory volume in 1 s (FEV₁), forced vital capacity, FEV₁ percent predicted (FEV₁%pre), and diffusion capacity of carbon monoxide percent predicted (DLCO%pre) in COPD patients were significantly lower than in those of the control group (P<0.05). MMP-2, MMP-9, and TIMP-1 expression levels were significantly higher in the COPD group than in control, especially the severe group (P<0.05). Septa thickness was negatively correlated with FEV₁%pre (r=−0.335; P<0.05) and positively correlated with MMP-2 and TIMP-1 expression (P<0.05). Proportion of collagenous fiber was negatively correlated with FEV₁%pre and DLCO%pre (P<0.01), and positively correlated with MMP-2, MMP-9, and TIMP-1 expression (P<0.01). Proportion of elastic fibers was negatively correlated with collagenous fiber.

Conclusions

The pathological alteration of alveolar septa was correlated with pulmonary function and expression levels of MMP-2, MMP-9, and TIMP-1, which can play vital roles in COPD progression.

Influence of Obesity on the Organization of the Extracellular Matrix and Satellite Cell Functions After Combined Muscle and Thorax Trauma in C57BL/6J Mice

Obesity has been described as a major factor of health risk in modern society. Next to intricately linked comorbidities like coronary artery disease or diabetes, an influence of obesity on regeneration after muscle injury has been described previously. However, the influence of obesity on tissue regeneration in a combined trauma, merging the more systemic influence of a blunt lung trauma and the local blunt muscle trauma, has not been investigated yet. Therefore, the aim of this study was to investigate the influence of obesity on regeneration in a mouse model that combined both muscle and thorax trauma. Using gene expression analysis, a focus was put on the structure as well as the organization of the extracellular matrix and on functional satellite cell physiology. An increased amount of debris in the lung of obese mice compared to normal weight mice up to 192 h after combined trauma based on visual assessment can be reported which is accompanied by a decreased response of Mmp2 in obese mice. Additionally, a delayed and elongated response of inhibitor genes like Timp1 has been revealed in obese mice. This elongated response to the trauma in obese mice can also be seen in plasma based on increased levels of pro-inflammatory chemo- and cytokines (IL-6, MCP-1, and IL 23) 192 h post trauma. In addition to changes in the lung, morphological analysis of the injured extensor iliotibialis anticus of the left hind leg in lean and diet-induced obese mice revealed deposition of fat in the regenerating muscle in obese animals hindering the structure of a compact muscle. Additionally, decreased activation of satellite cells and changes in organization and build-up of the ECM could be detected, finally leading to a decreased stability of the regenerated muscle in obese mice. Both factors contribute to an attenuated response to the trauma by obese mice which is reflected by a statistically significant decrease in muscle force of obese mice compared to lean mice 192 h post trauma induction.

Mitochondria dysfunction and metabolic reprogramming as drivers of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease of unknown etiology. It is characterized by deposition of extracellular matrix proteins, like collagen and fibronectin in the lung interstitium leading to respiratory failure. Our understanding of the pathobiology underlying IPF is still incomplete; however, it is accepted that aging is a major risk factor in the disease while growing evidence suggests that the mitochondria plays an important role in the initiation and progression of pulmonary fibrosis. Mitochondria dysfunction and metabolic reprogramming had been identified in different IPF lung cells (alveolar epithelial cells, fibroblasts, and macrophages) promoting low resilience and increasing susceptibility to activation of profibrotic responses. Here we summarize changes in mitochondrial numbers, biogenesis, turnover and associated metabolic adaptations that promote disrepair and fibrosis in the lung. Finally, we highlight new possible therapeutic approaches focused on ameliorate mitochondrial dysfunction.

The Versatile Role of Matrix Metalloproteinase for the Diverse Results of Fibrosis Treatment

Fibrosis is a type of chronic organ failure, resulting in the excessive secretion of extracellular matrix (ECM). ECM protects wound tissue from infection and additional injury, and is gradually degraded during wound healing. For some unknown reasons, myofibroblasts (the cells that secrete ECM) do not undergo apoptosis; this is associated with the continuous secretion of ECM and reduced ECM degradation even during de novo tissue formation. Thus, matrix metalloproteinases (MMPs) are considered to be a potential target of fibrosis treatment because they are the main groups of ECM-degrading enzymes. However, MMPs participate not only in ECM degradation but also in the development of various biological processes that show the potential to treat diseases such as stroke, cardiovascular diseases, and arthritis. Therefore, treatment involving the targeting of MMPs might impede typical functions. Here, we evaluated the links between these MMP functions and possible detrimental effects of fibrosis treatment, and also considered possible approaches for further applications.

Cancer Conditioned Medium Modulates Functional and Phenotypic Properties of Human Decidua Parietalis Mesenchymal Stem/Stromal Cells

Background

Mesenchymal Stem/Stromal Cells (MSCs) from the decidua parietalis (DPMSCs) of human term placenta express several molecules with important biological and immunological properties. DPMSCs induce natural killer cell expression of inflammatory receptors and their cytotoxic activity against cancer cells. These properties make DPMSCs promising therapeutical agent for cancer. The successful development of MSCs as an anti-cancer therapeutic cells rely on their ability to function in a hostile inflammatory and oxidative stress cancer environment. Here, we studied the effects of conditioned medium obtained from the culture of breast cancer cells (CMMDA-231) on the functional and phenotypic properties of DPMSCs.

Methods

DPMSCs were cultured with CMMDA-231 and important functions of DPMSCs were measured. The effect of CMMDA-231 on DPMSC expression of several genes with different functions was also evaluated.

Results

DPMSCs were able to function in response to CMMDA-231, but with reduced proliferative and adhesive potentials. Preconditioning of DPMSCs with CMMDA-231 enhanced their adhesion while reducing their invasion. In addition, CMMDA-231 modulated DPMSC expression of many genes with various functional (i.e., proliferation, adhesion, and invasion) properties. DPMSCs also showed increased expression of genes with anti-cancer property.

Conclusion

These data show the ability of DPMSCs to survive and function in cancer environment. In addition, preconditioning of DPMSCs with CMMDA-231 enhanced their anti-cancer properties and thus demonstrating their potential as an anti-cancer therapeutic agent. However, future studies are essential to reveal the mechanism underlying the effects of MDA-231 on DPMSC functional activities and also to confirm the anti-cancer therapeutic potential of DPMSCs.

Lung fibroblasts express a miR-19a-19b-20a sub-cluster to suppress TGF-β-associated fibroblast activation in murine pulmonary fibrosis

Lung fibroblasts play a pivotal role in pulmonary fibrosis, a devastating lung disease, by producing extracellular matrix. MicroRNAs (miRNAs) suppress numerous genes post-transcriptionally; however, the roles of miRNAs in activated fibroblasts in fibrotic lungs remain poorly understood. To elucidate these roles, we performed global miRNA-expression profiling of fibroblasts from bleomycin- and silica-induced fibrotic lungs and investigated the functions of miRNAs in activated lung fibroblasts. Clustering analysis of global miRNA-expression data identified miRNA signatures exhibiting increased expression during fibrosis progression. Among these signatures, we found that a miR-19a-19b-20a sub-cluster suppressed TGF-β-induced activation of fibroblasts in vitro. Moreover, to elucidate whether fibroblast-specific intervention against the sub-cluster modulates pathogenic activation of fibroblasts in fibrotic lungs, we intratracheally transferred the sub-cluster-overexpressing fibroblasts into bleomycin-treated lungs. Global transcriptome analysis of the intratracheally transferred fibroblasts revealed that the sub-cluster not only downregulated expression of TGF-β-associated pro-fibrotic genes, including Acta2, Col1a1, Ctgf, and Serpine1, but also upregulated expression of the anti-fibrotic genes Dcn, Igfbp5, and Mmp3 in activated lung fibroblasts. Collectively, these findings indicated that upregulation of the miR-19a-19b-20a sub-cluster expression in lung fibroblasts counteracted TGF-β-associated pathogenic activation of fibroblasts in murine pulmonary fibrosis.

Retracted: Pulmonary fibrosis of mice and its molecular mechanism following chronic inhaled exposure to TiO2 nanoparticles

Nanoparticulate titanium dioxide (nano-TiO2 ) has been widely used in industry, medicine and daily life. However, assessment of nano-TiO2 toxicity on health is an important occupational safety issue. Numerous studies have demonstrated that nano-TiO2 can induced sustained pulmonary inflammation, but whether chronic exposure to nano-TiO2 results in pulmonary fibrosis is unclear. In this study, therefore, nano-TiO2 was administered to the male mice by nasal administration for six consecutive months, the inflammatory and/or fibrogenic responses induced by nano-TiO2 were investigated. The results showed that chronic inhaled nano-TiO2 induced pulmonary inflammation and firosis, increased expression of inflammatory cytokines and fibrotic cytokines including nuclear factor-κB, interleukin-1β, tumor necrosis factor-α, monocyte chemotactic protein 1, macrophage inflammatory protein-2, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, transform growth factor -β1, osteopontin, matrix metalloproteinase-1, -2, -3, and -9, tissue inhibitors of metalloproteinase-1, collagen, platelet derived growth factor, and connective tissue growth factor in mouse lung. Taken together, nano-TiO2 -induced pulmonary inflammation and fibrosis are closely associated with increased expression of inflammatory and/or fibrotic cytokines, an imbalanced production of MMPs and TIMP-1 that favors fibrosis in mice, implying that nano-TiO2 may lead to potential health effects.

Global gene profiling of aging lungs in Atp8b1 mutant mice

Objective

Recent studies implicate cardiolipin oxidation in several age-related diseases. Atp8b1 encoding Type 4 P-type ATPases is a cardiolipin transporter. Mutation in Atp8b1 gene or inflammation of the lungs impairs the capacity of Atp8b1 to clear cardiolipin from lung fluid. However, the link between Atp8b1 mutation and age-related gene alteration is unknown. Therefore, we investigated how Atp8b1 mutation alters age-related genes.

Methods

We performed Affymetrix gene profiling of lungs isolated from young (7-9 wks, n=6) and aged (14 months, 14 M, n=6) C57BL/6 and Atp8b1 mutant mice. In addition, Ingenuity Pathway Analysis (IPA) was performed. Differentially expressed genes were validated by quantitative real-time PCR (qRT-PCR).

Results

Global transcriptome analysis revealed 532 differentially expressed genes in Atp8b1 lungs, 157 differentially expressed genes in C57BL/6 lungs, and 37 overlapping genes. IPA of age-related genes in Atp8b1 lungs showed enrichment of Xenobiotic metabolism and Nrf2-mediated signaling pathways. The increase in Adamts2 and Mmp13 transcripts in aged Atp8b1 lungs was validated by qRT-PCR. Similarly, the decrease in Col1a1 and increase in Cxcr6 transcripts was confirmed in both Atp8b1 mutant and C57BL/6 lungs.

Conclusion

Based on transcriptome profiling, our study indicates that Atp8b1 mutant mice may be susceptible to age-related lung diseases.

Ilomastat, a synthetic inhibitor of MMPs, prevents lung injury induced by γ-ray irradiation in mice

Lung injury is one of the pathological features in human or animal after radiation and the main side effect for patient after lung cancer radiotherapy. The efficient protective strategy still needs to exploit and the underlying mechanisms remain to be investigated. We found that the expression and activity of matrix metalloproteinases (MMPs) significantly increased at the early stage of radiation-induced lung injury (RILI). Pretreatment with Ilomastat, a synthetic inhibitor of MMPs, decreased the expression and activity of MMPs and significantly alleviated the lung inflammation and fibrosis in the irradiated mice, as well as enhanced the survival of irradiated mice. In addition, the levels of TGF-β, IL-6, TNF-α and IL-1β in the tissues dramatically reduced in the irradiated mice pretreated with Ilomastat. Furthermore, our experiments in vitro also showed that radiation significantly increased the MMPs activity, and Ilomastat pretreatment inhibited the activity of MMPs activated by irradiation and increased the cell survival. It is the first report, to our knowledge, to demonstrate that Ilomastat is a potential effective reliever for RILI and MMPs may play important roles in the process of RILI.

Pannexin hemichannels: A novel promising therapy target for oxidative stress related diseases

Pannexins, which contain three subtypes: pannexin-1, -2, and -3, are vertebrate glycoproteins that form non-junctional plasma membrane intracellular hemichannels via oligomerization. Oxidative stress refers to an imbalance of the generation and elimination of reactive oxygen species (ROS). Studies have shown that elevated ROS levels are pivotal in the development of a variety of diseases. Recent studies indicate that the occurrence of these oxidative stress related diseases is associated with pannexin hemichannels. It is also reported that pannexins regulate the production of ROS which in turn may increase the opening of pannexin hemichannels. In this paper, we review recent researches about the important role of pannexin hemichannels in oxidative stress related diseases. Thus, pannexin hemichannels, novel therapeutic targets, hold promise in managing oxidative stress related diseases such as the tumor, inflammatory bowel diseases (IBD), pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), cardiovascular disease, insulin resistance (IR), and neural degeneration diseases.

Role of Proteases in Lung Disease: A Brief Overview

Proteases play an important role in health and disease of the lung. In the normal lungs, proteases maintain their homeostatic functions that regulate processes like its regeneration and repair. Dysregulation of proteases–antiproteases balance is crucial in the manifestation of different types of lung diseases. Chronic inflammatory lung pathologies are associated with a marked increase in protease activities. Thus, in addition to protease activities, inhibition of anti-proteolytic control mechanisms are also important for effective microbial infection and inflammation in the lung. Herein, we briefly summarize the role of different proteases and to some extent antiproteases in regulating a variety of lung diseases.

Lung Microtissue Array to Screen the Fibrogenic Potential of Carbon Nanotubes

Due to their excellent physical and chemical characteristics, multi-wall carbon nanotubes (MWCNT) have the potential to be used in structural composites, conductive materials, sensors, drug delivery and medical imaging. However, because of their small-size and light-weight, the applications of MWCNT also raise health concerns. In vivo animal studies have shown that MWCNT cause biomechanical and genetic alterations in the lung tissue which lead to lung fibrosis. To screen the fibrogenic risk factor of specific types of MWCNT, we developed a human lung microtissue array device that allows real-time and in-situ readout of the biomechanical properties of the engineered lung microtissue upon MWCNT insult. We showed that the higher the MWCNT concentration, the more severe cytotoxicity was observed. More importantly, short type MWCNT at low concentration of 50 ng/ml stimulated microtissue formation and contraction force generation, and caused substantial increase in the fibrogenic marker miR-21 expression, indicating the high fibrogenic potential of this specific carbon nanotube type and concentration. The presented microtissue array system provides a powerful tool for high-throughput examination of the therapeutic and toxicological effects of target compounds in realistic tissue environment.

Aliskiren attenuates bleomycin-induced pulmonary fibrosis in rats: focus on oxidative stress, advanced glycation end products, and matrix metalloproteinase-9

Pulmonary fibrosis is a progressive lung disorder with high mortality rate and limited successful treatment. This study was designed to assess the potential anti-oxidant and anti-fibrotic effects of aliskiren (Alsk) during bleomycin (BLM)-induced pulmonary fibrosis. Male Wistar rats were used as control untreated or treated with the following: a single dose of 2.5 mg/kg of BLM endotracheally and BLM and Alsk (either low dose 30 mg/kg/day or high dose 60 mg/kg/day), and another group was given Alsk 60 mg/kg/day alone. Alsk was given by gavage. Alsk anti-oxidant and anti-fibrotic effects were assessed. BLM significantly increased relative lung weight and the levels of lactate dehydrogenase and total and differential leucocytic count in bronchoalveolar lavage that was significantly ameliorated by high-dose Alsk treatment. As markers of oxidative stress, BLM caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease of superoxide dismutase and glutathione transferase enzymes. High-dose Alsk treatment restored these markers toward normal values. Alsk counteracted the overexpression of advanced glycation end products, matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 in lung tissue induced by BLM. Fibrosis assessed by measuring hydroxyproline content, which markedly increased in the BLM group, was also significantly reduced by Alsk. These were confirmed by histopathological and immunohistochemical examination which revealed that Alsk attenuates signs of pulmonary fibrosis and decreased the overexpressed MMP-9 and transforming growth factor β1. Collectively, these findings indicate that Alsk has a potential anti-fibrotic effect beside its anti-oxidant activity.

Matrix metalloproteinases as therapeutic targets for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a restrictive lung disease that is associated with high morbidity and mortality. Current medical therapies are not fully effective at limiting mortality in patients with IPF, and new therapies are urgently needed. Matrix metalloproteinases (MMPs) are proteinases that, together, can degrade all components of the extracellular matrix and numerous nonmatrix proteins. MMPs and their inhibitors, tissue inhibitors of MMPs (TIMPs), have been implicated in the pathogenesis of IPF based upon the results of clinical studies reporting elevated levels of MMPs (including MMP-1, MMP-7, MMP-8, and MMP-9) in IPF blood and/or lung samples. Surprisingly, studies of gene-targeted mice in murine models of pulmonary fibrosis (PF) have demonstrated that most MMPs promote (rather than inhibit) the development of PF and have identified diverse mechanisms involved. These mechanisms include MMPs: (1) promoting epithelial-to-mesenchymal transition (MMP-3 and MMP-7); (2) increasing lung levels or activity of profibrotic mediators or reducing lung levels of antifibrotic mediators (MMP-3, MMP-7, and MMP-8); (3) promoting abnormal epithelial cell migration and other aberrant repair processes (MMP-3 and MMP-9); (4) inducing the switching of lung macrophage phenotypes from M1 to M2 types (MMP-10 and MMP-28); and (5) promoting fibrocyte migration (MMP-8). Two MMPs, MMP-13 and MMP-19, have antifibrotic activities in murine models of PF, and two MMPs, MMP-1 and MMP-10, have the potential to limit fibrotic responses to injury. Herein, we review what is known about the contributions of MMPs and TIMPs to the pathogenesis of IPF and discuss their potential as therapeutic targets for IPF.

Matrix metalloproteinases contribute to the regulation of chemokine expression and pulmonary inflammation in Cryptococcus infection

Matrix metalloproteinases (MMPs) are a family of extracellular proteases that play roles in regulating the immune response in inflammatory processes. Previous studies indicated that different MMPs were involved in the host defence and tissue damage in response to different pathogens. However, the contributions of MMPs during Cryptococcus infection have not been addressed clearly. Here, we examined the expression and activity of MMPs during Cryptococcus infection. Among MMP family members, we found significant increases of MMP-3 and MMP-12 mRNA levels and MMP12 zymographic activities in response to C. neoformans but not C. gattii infection. The expression of MMP12 was induced in RAW cells after C. neoformans treatment and in alveolar macrophages purified from C. neoformans-infected mice. Interestingly, administration of MMP inhibitor GM6001 into C. neoformans-infected mice resulted in a significantly increased pulmonary fungal burden with attenuated inflammatory cell infiltration. Corresponding to this finding, the expression of the macrophage- and neutrophil-attracting chemokines CCL2 and CXCL1 was inhibited in the GM6001-treated group and MMP12 levels were found to be correlated strongly with CCL2 mRNA expression. Thus, our data suggest that the induction of MMPs by C. neoformans infection potentiates inflammatory cell infiltration by modulating pulmonary chemokines, thereby promoting effective host immunity to pulmonary Cryptococcus infection.

Reduced supply of monocyte-derived macrophages leads to a transition from nodular to diffuse lesions and tissue cell activation in silica-induced pulmonary fibrosis in mice

Pulmonary fibrosis (PF) is an intractable disorder with a poor prognosis. Lung macrophages have been reported to regulate both progression and remission of bleomycin-induced diffuse PF. However, it remains unclear how macrophages contribute to silica-induced progressive nodular PF and the associated tissue cell responses in vivo. We found that lack of monocyte-derived macrophages results in the formation of diffuse PF after silica instillation. We found that the proportion and the number of monocyte-derived macrophages were persistently higher in silica-induced progressive PF compared with bleomycin-induced PF. Surprisingly, in Ccr2(-/-) mice, in which monocyte-derived macrophage infiltration is impaired, silica administration induced diffuse PF with loose nodule formation and greater activation of tissue cells. In the diffuse lesions, the distribution of epithelial cells, distribution of myofibroblasts, and architecture of the basement membrane were disrupted. Consistent with the development of diffuse lesions, genes that were differentially expressed in CD45(-) tissue cells from the lung of wild-type and Ccr2(-/-) mice were highly enriched in human diffuse, progressive PF. In gene ontology network analyses, many of these genes were associated with tissue remodeling and included genes not previously associated with PF, such as Mmp14, Thbs2, and Fgfr4. Overall, these results indicate that monocyte-derived macrophages prevent transition from nodular to diffuse silica-induced PF, potentially by regulating tissue cell responses.

Common and distinct mechanisms of induced pulmonary fibrosis by particulate and soluble chemical fibrogenic agents

Pulmonary fibrosis results from the excessive deposition of collagen fibers and scarring in the lungs with or without an identifiable cause. The mechanism(s) underlying lung fibrosis development is poorly understood, and effective treatment is lacking. Here we compared mouse lung fibrosis induced by pulmonary exposure to prototypical particulate (crystalline silica) or soluble chemical (bleomycin or paraquat) fibrogenic agents to identify the underlying mechanisms. Young male C57BL/6J mice were given silica (2 mg), bleomycin (0.07 mg), or paraquat (0.02 mg) by pharyngeal aspiration. All treatments induced significant inflammatory infiltration and collagen deposition, manifesting fibrotic foci in silica-exposed lungs or diffuse fibrosis in bleomycin or paraquat-exposed lungs on day 7 post-exposure, at which time the lesions reached their peaks and represented a junction of transition from an acute response to chronic fibrosis. Lung genome-wide gene expression was analyzed, and differential gene expression was confirmed by quantitative RT-PCR, immunohistochemistry, and immunoblotting for representative genes to demonstrate their induced expression and localization in fibrotic lungs. Canonical signaling pathways, gene ontology, and upstream transcription networks modified by each agent were identified. In particular, these inducers elicited marked proliferative responses; at the same time, silica preferentially activated innate immune functions and the defense against foreign bodies, whereas bleomycin and paraquat boosted responses related to cell adhesion, platelet activation, extracellular matrix remodeling, and wound healing. This study identified, for the first time, the shared and unique genes, signaling pathways, and biological functions regulated by particulate and soluble chemical fibrogenic agents during lung fibrosis, providing insights into the mechanisms underlying human lung fibrotic diseases.

Amelioration of bleomycin-induced pulmonary fibrosis in a mouse model by a combination therapy of bosentan and imatinib

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is characterized by alveolitis, progressing into fibrosis. Due to the involvement of both endothelin and platelet-derived growth factor signaling in IPF, combination effects of a bosentan and imatinib were studied in mouse model of bleomycin-induced pulmonary fibrosis.

METHODS

Mice subjected to bleomycin instillation (0.05 U) and were administered with either bosentan (100 mg/kg) and/or imatinib (50 mg/kg). Inflammatory cell count, total protein estimation in bronchoalveolar lavage fluid, lung edema, superoxide dismutase, catalase, myeloperoxidase activities, and Hematoxylin & Eosin staining were performed on day 7. Hydroxyproline content, α-smooth muscle actin (SMA), collagens I and III gene expression analysis, immunohistochemistry, matrix metalloproteinases-9 and -2 activities, trichrome and sirius red staining were performed on day 21.

RESULTS

Combination treatment with bosentan and imatinib prevented bleomycin-induced mortality and loss of body weight more than the individual agents. On day 7, the combination therapy attenuated bleomycin-induced increase of total and differential inflammatory cell counts, total proteins, lung wet/dry weight ratio, myeloperoxidase activity, lung inflammatory cell infiltration more than individual agents alone. Bosentan but not imatinib ameliorated superoxide dismutase and catalase activities, which were lowered following bleomycin instillation. On day 21, combination therapy ameliorated bleomycin-induced increase of fibrosis score, collagen deposition, protein and gene expression of SMA, mRNA levels of collagens-I and -III, matrix metalloproteinase-9 and -2 activities more than monotherapy.

CONCLUSION

Combination of bosentan and imatinib exerted more enhanced protection against bleomycin-induced inflammation and fibrosis than either of the agents alone.

Protective effect of emodin against airway inflammation in the ovalbumin-induced mouse model

OBJECTIVE

To investigate whether emodin exerts protective effects on mouse with allergic asthma.

METHODS

A mouse model of allergic airway inflflammation was employed. The C57BL/6 mice sensitized and challenged with ovalbumin (OVA) were intraperitoneally administered 10 or 20 mg/kg emodin for 3 days during OVA challenge. Animals were sacrificed 48 h after the last challenge. Inflammatory cell count in the bronchoalveolar lavage fluid (BALF) was measured. The levels of interleukin (IL)-4, IL-5, IL-13 and eotaxin in BALF and level of immunoglobulin E (IgE) in serum were measured with enzyme-linked immuno sorbent assay kits. The mRNA expressions of IL-4, IL-5, heme oxygenase (HO)-1 and matrix metalloproteinase-9 (MMP-9) were determined by real-time quantitative polymerase chain reaction.

RESULTS

Emodin induced significant suppression of the number of OVA-induced total inflammatory cells in BALF. Treatment with emodin led to significant decreases in the levels of IL-4, IL-5, IL-13 and eotaxin in BALF and total IgE level in serum. Histological examination of lung tissue revealed marked attenuation of allergen-induced lung eosinophilic inflammation. Additionally, emodin suppressed IL-4, IL-5 and MMP-9 mRNA expressions and induced HO-1 mRNA expression.

CONCLUSION

Emodin exhibits anti-inflammatory activity in the airway inflammation mouse model, supporting its therapeutic potential for the treatment of allergic bronchial asthma.

Indications for distinct pathogenic mechanisms of asbestos and silica through gene expression profiling of the response of lung epithelial cells

Occupational and environmental exposures to airborne asbestos and silica are associated with the development of lung fibrosis in the forms of asbestosis and silicosis, respectively. However, both diseases display distinct pathologic presentations, likely associated with differences in gene expression induced by different mineral structures, composition and bio-persistent properties. We hypothesized that effects of mineral exposure in the airway epithelium may dictate deviating molecular events that may explain the different pathologies of asbestosis versus silicosis. Using robust gene expression-profiling in conjunction with in-depth pathway analysis, we assessed early (24 h) alterations in gene expression associated with crocidolite asbestos or cristobalite silica exposures in primary human bronchial epithelial cells (NHBEs). Observations were confirmed in an immortalized line (BEAS-2B) by QRT-PCR and protein assays. Utilization of overall gene expression, unsupervised hierarchical cluster analysis and integrated pathway analysis revealed gene alterations that were common to both minerals or unique to either mineral. Our findings reveal that both minerals had potent effects on genes governing cell adhesion/migration, inflammation, and cellular stress, key features of fibrosis. Asbestos exposure was most specifically associated with aberrant cell proliferation and carcinogenesis, whereas silica exposure was highly associated with additional inflammatory responses, as well as pattern recognition, and fibrogenesis. These findings illustrate the use of gene-profiling as a means to determine early molecular events that may dictate pathological processes induced by exogenous cellular insults. In addition, it is a useful approach for predicting the pathogenicity of potentially harmful materials.

Asbestos-associated mesothelial cell autoantibodies promote collagen deposition in vitro

Fibrosis, characterized by excessive collagen protein deposition, is a progressive disease that can fatally inhibit organ function. Prolonged exposure to pathogens or environmental toxicants such as asbestos can lead to chronic inflammatory responses associated with fibrosis. Significant exposure to amphibole asbestos has been reported in and around Libby, Montana due to local mining of asbestos-contaminated vermiculite. These exposures have been implicated in a unique disease etiology characterized predominantly by pleural disorders, including fibrosis. We recently reported the discovery of mesothelial cell autoantibodies (MCAAs) in the sera of Libby residents and demonstrated a positive and significant correlation with pleural disease; however, a mechanistic link was not determined. Here we demonstrate that MCAAs induce pleural mesothelial cells to produce a collagen matrix but do not affect production of the pro-inflammatory cytokine tumor growth factor-β. While autoantibodies commonly induce a pro-fibrotic state by inducing epithelial-mesenchymal transition (EMT) of target cells, we found no evidence supporting EMT in cells exposed to MCAA positive human sera. Although implicated in other models of pulmonary fibrosis, activity of the protein SPARC (secreted protein, acidic and rich in cysteine) did not affect MCAA-induced collagen deposition. However, matrix formation was dependent on matrix metalloproteinase (MMP) activity, and we noted increased expression of MMP-8 and -9 in supernatants of mesothelial cells incubated with MCAA positive sera compared to control. These data suggest a mechanism by which MCAA binding leads to increased collagen deposition through altering MMP expression and provides an important mechanistic link between MCAAs and asbestos-related, autoimmune-induced pleural fibrosis.

Rac2 is involved in bleomycin-induced lung inflammation leading to pulmonary fibrosis

BACKGROUND

Pulmonary fibrotic diseases induce significant morbidity and mortality, for which there are limited therapeutic options available. Rac2, a ras-related guanosine triphosphatase expressed mainly in hematopoietic cells, is a crucial molecule regulating a diversity of mast cell, macrophage, and neutrophil functions. All these cell types have been implicated in the development of pulmonary fibrosis in a variety of animal models. For the studies described here we hypothesized that Rac2 deficiency protects mice from bleomycin-induced pulmonary fibrosis.

METHODS

To determine the role of Rac2 in pulmonary fibrosis we used a bleomycin-induced mouse model. Anesthetized C57BL/6 wild type and rac2-/- mice were instilled intratracheally with bleomycin sulphate (1.25 U/Kg) or saline as control. Bronchoalveolar lavage (BAL) samples were collected at days 3 and 7 of treatment and analyzed for matrix metalloproteinases (MMPs). On day 21 after bleomycin treatment, we measured airway resistance and elastance in tracheotomized animals. Lung sections were stained for histological analysis, while homogenates were analyzed for hydroxyproline and total collagen content.

RESULTS

BLM-treated rac2-/- mice had reduced MMP-9 levels in the BAL on day 3 and reduced neutrophilia and TNF and CCL3/MIP-1α levels in the BAL on day 7 compared to BLM-treated WT mice. We also showed that rac2-/- mice had significantly lower mortality (30%) than WT mice (70%) at day 21 of bleomycin treatment. Lung function was diminished in bleomycin-treated WT mice, while it was unaffected in bleomycin-treated rac2-/- mice. Histological analysis of inflammation and fibrosis as well as collagen and hydroxyproline content in the lungs did not show significant differences between BLM-treated rac2-/- and WT and mice that survived to day 21.

CONCLUSION

Rac2 plays an important role in bleomycin-induced lung injury. It is an important signaling molecule leading to BLM-induced mortality and it also mediates the physiological changes seen in the airways after BLM-induced injury.

Effects of lentiviral vector-mediated TRADD expression on the inhibition of hypertrophic scar formation

The tumor necrosis factor receptor-associated death domain protein (TRADD) regulates cell proliferation and apoptosis via tumor necrosis factor alpha (TNF-α)-mediated signaling pathways. Low levels of TRADD expression may result in the excessive proliferation of hypertrophic scar fibroblasts (HSFb). This study investigated the effects of a lentiviral vector carrying the human tradd gene on the proliferation, apoptosis and type I collagen synthesis of HSFb and embryonic fibroblasts (EFb) and further explored the resulting effects on hypertrophic scars (HS). We utilized cytoimmunofluorescence and Western blotting to confirm the expression of TRADD in HSFb and EFb. A PLVX-TRADD-EGFP lentivirus was prepared and transfected into EFb and HSFb, and then the expression of a TRADD-GFP-FLAG fusion protein was detected in HSFb and EFb. After stimulation with 10 ng/mL TNF-α, cell proliferation, apoptosis, and the synthesis of type I collagen were assessed. Our results show that the expression level of TRADD was significantly lower in HSFb than in EFb. A biologically active PLVX-TRADD-EGFP lentivirus was constructed and transfected into HSFb and EFb. The TRADD-GFP-FLAG fusion protein was effectively expressed in HSFb and EFb. Either alone or in combination with 10 ng/mL TNF-α, the PLVX-TRADD-EGFP lentivirus inhibited proliferation, caused a G2/M phase arrest, induced the appearance of a sub-G1 apoptotic peak and inhibited the secretion of type I collagen by HSFb without significantly affecting EFb. These results suggest that the low expression of TRADD in HSFb is a principal reason for their excessive proliferation. The transfection of a PLVX-TRADD-EGFP lentivirus led to the normal expression of TRADD in HSFb. When combined with 10 ng/mL TNF-α, a PLVX-TRADD-EGFP lentivirus transfection could inhibit cell proliferation, promote apoptosis, and reduce the secretion of type I collagen in HSFb, thereby reducing HS formation.

Polyhexamethyleneguanidine phosphate induces severe lung inflammation, fibrosis, and thymic atrophy

Polyhexamethyleneguanidine phosphate (PHMG-P) has been widely used as a disinfectant because of its strong bactericidal activity and low toxicity. However, in 2011, the Korea Centers for Disease Control and Prevention and the Ministry of Health and Welfare reported that a suspicious outbreak of pulmonary disease might have originated from humidifier disinfectants. The purpose of this study was to assess the toxicity of PHMG-P following direct exposure to the lung. PHMG-P (0.3, 0.9, or 1.5 mg/kg) was instilled into the lungs of mice. The levels of proinflammatory markers and fibrotic markers were quantified in lung tissues and flow cytometry was used to evaluate T cell distribution in the thymus. Administration of PHMG-P induced proinflammatory cytokines elevation and infiltration of immune cells into the lungs. Histopathological analysis revealed a dose-dependent exacerbation of both inflammation and pulmonary fibrosis on day 14. PHMG-P also decreased the total cell number and the CD4(+)/CD8(+) cell ratio in the thymus, with the histopathological examination indicating severe reduction of cortex and medulla. The mRNA levels of biomarkers associated with T cell development also decreased markedly. These findings suggest that exposure of lung tissue to PHMG-P leads to pulmonary inflammation and fibrosis as well as thymic atrophy.

Therapeutic Effect of Broussonetia papyrifera and Lonicera japonica in Ovalbumin-induced Murine Asthma Model

Broussonetia papyrifera (L.) Vent. and Lonicera japonica Thunb. have been used in recent medicinal research for their antioxidative and anti-inflammatory properties. The present study investigated the therapeutic efficacy of B. papyrifera and L. japonica ethanolic extracts in a murine model of ovalbumin-induced asthma, in which intra-peritoneal (IP) injections and aerosol ovalbumin delivery were used to induce allergic asthma. Bronchioalveolar lavage fluid (BALF), serum samples, lungs and livers were collected from the experimental groups. In the groups treated with B. papyrifera and L. japonica extracts, CD3, CD4, serum IgE and IL-4 levels; activities of matrix metalloproteinase (MMP)-2 and MMP-9; and eotaxin levels in the BALF significantly decreased to near normal levels. Results of a histopathological analysis showed that the level of inflammation and mucous secretions reduced in the treated groups compared to the corresponding levels in the other groups. Moreover, results of a serum enzymatic analysis showed the non-toxic nature of the extracts in the B. papyrifera and L. japonica treated groups. Taken together, these results clearly indicate that the B. papyrifera and L. japonica extracts may be very effective against asthma and inflammation related diseases.

Genes involved in innate immunity associated with asbestos-related fibrotic changes

Objectives

To determine whether genetic polymorphisms in several candidate genes related to innate immunity and protease–antiprotease balance modify individual susceptibility to develop asbestos-related fibrotic pleuropulmonary changes.

Methods

Sixteen polymorphisms from nine genes (NLRP3, CARD8, TNF, TGFB1, GC, MMP1, MMP9, MMP12 and TIMP2) were genotyped from 951 Finnish asbestos-exposed workers. The genotype/haplotype data were compared to signs of fibrosis and pleural thickenings using linear and logistic regression analysis adjusted for potential confounders.

Results

A functional polymorphism (Q705K; rs35829419) in the NLRP3 gene was associated with interstitial lung fibrosis (p=0.013), and the TGFB1 rs2241718 SNP with visceral pleural fibrosis (VPF) (p=0.044). In stratified analysis, the carriage of at least one NLRP3 variant allele conferred a 2.5-fold increased risk for pathological interstitial lung fibrosis (OR 2.44, 95% CI 0.97 to 6.14). Conversely, the carriage of at least one TGFB1 rs2241718 variant allele protected against VPF (OR 0.62, 95% CI 0.39 to 0.98). The TIMP2 rs2277698 SNP and a haplotype consisting of the TGFB1 rs1800469 and rs1800470 SNPs were associated with the degree of pleural thickening calcification (p=0.037 and p=0.035), and the CARD8 rs2043211 SNP with the greatest thickness of pleural plaques (p=0.015).

Conclusions

Our results support the hypothesis that the NLRP3 inflammasome is important in the development of fibrotic lung disease by associating the NLRP3 rs35829419 variant allele with increased risk of asbestos-related interstitial lung fibrosis, and the TGFB1 rs2241718 variant allele with decreased risk of asbestos-related VPF. Polymorphisms in CARD8 and TIMP2 are proposed to modify the development and/or calcification of pleural thickenings.

Chronic exposure to carbon nanotubes induces invasion of human mesothelial cells through matrix metalloproteinase-2

Malignant mesothelioma is one of the most aggressive forms of cancer known. Recent studies have shown that carbon nanotubes (CNTs) are biopersistent and induce mesothelioma in animals, but the underlying mechanisms are not known. Here, we investigate the effect of long-term exposure to high aspect ratio CNTs on the aggressive behaviors of human pleural mesothelial cells, the primary cellular target of human lung mesothelioma. We show that chronic exposure (4 months) to single- and multiwalled CNTs induced proliferation, migration, and invasion of the cells similar to that observed in asbestos-exposed cells. An up-regulation of several key genes known to be important in cell invasion, notably matrix metalloproteinase-2 (MMP-2), was observed in the exposed mesothelial cells as determined by real-time PCR. Western blot and enzyme activity assays confirmed the increased expression and activity of MMP-2. Whole genome microarray analysis further indicated the importance of MMP-2 in the invasion gene signaling network of the exposed cells. Knockdown of MMP-2 in CNT and asbestos-exposed cells by shRNA-mediated gene silencing effectively inhibited the aggressive phenotypes. This study demonstrates CNT-induced cell invasion and indicates the role of MMP-2 in the process.

Noninvasive monitoring of pulmonary fibrosis by targeting matrix metalloproteinases (MMPs)

While idiopathic pulmonary fibrosis (PF) is a devastating lung disease, the management of PF including effective monitoring of disease progression remains a challenge. Herein, we introduce a novel, fast, and ultrasensitive metalloproteinase (MMP) activatable optical probe, named MMP-P12, to noninvasively monitor PF progression and response to PF treatment. A bleomycin (BLM)-induced mouse PF model was subjected noninvasively to optical imaging at various time points after BLM treatment. The mouse PF model developed fibrosis during 21 days of experimental period, and the progression of PF was well correlated with the stepwise increase of MMP-2 expression as examined by quantitative RT-PCR and Western blot analysis on the 7-, 14-, and 21-day post-BLM administration. On these days, MMP-activated fluorescence images were acquired in vivo and ex vivo. Signal quantification showed time-dependent lung-specific incremental increases in fluorescence signals. As a treatment for PF, secretoglobin 3A2 was daily administered intravenously for five days starting on day seven of BLM administration, which resulted in reduced MMP-2 activity and reduction of PF as previously demonstrated. Importantly, the fluorescence signal that reflected MMP activity also decreased in intensity. In conclusion, MMPs may play an important role in PF development and the MMP-P12 probe could be a promising tool for PF detection, even at an early stage of the disease as well as an indicator of therapy response.

Didecyldimethylammonium chloride induces pulmonary fibrosis in association with TGF-β signaling in mice

Didecyldimethylammonium chloride (DDAC) is a representative dialkyl-quaternary ammonium compound that is used as a disinfectant against several pathogens and is also used in commercial, industrial, and residential settings. We previously investigated toxicity on air way system following single instillation of DDAC to the lungs in mice, and found that DDAC causes pulmonary injury, which is associated with altered antioxidant antimicrobial responses; the inflammatory phase is accompanied or followed by fibrotic response. The present study was conducted to monitor transforming growth factor-β (TGF-β) signaling in pulmonary fibrosis induced by DDAC. Mice were intratracheally instilled with DDAC and sacrificed 1, 3, or 7 days after treatment to measure TGF-β signaling. In order to further evaluate TGF-β signaling, we treated isolated mouse lung fibroblasts with DDAC. Fibrotic foci were observed in the lungs on day 3, and were widely extended on day 7, with evidence of increased α-smooth muscle actin-positive mesenchymal cells and upregulation of Type I procollagen mRNA. Developing fibrotic foci were likely associated with increased expression of Tgf-β1 mRNA, in addition to decreased expression of Bone morphogenetic protein-7 mRNA. In fibrotic lung samples, the expression of phosphorylated SMAD2/3 was considerably higher than that of phosphorylated SMAD1/5. In isolated lung fibroblasts, the mRNA levels of Tgf-β1 were specifically increased by DDAC treatment, which prolonged phosphorylation of SMAD2/3. These effects were abolished by treatment with SD208 - a TGF-βRI kinase inhibitor. The results suggest that DDAC induces pulmonary fibrosis in association with TGF-β signaling.

Simultaneous demonstration of gelatinolytic activity, morphology, and immunohistochemical reaction using zymography film

In situ zymography has been used to assess gelatinolytic activity, which is mainly due to matrix metalloproteinases (MMPs) in cancer tissues. MMPs play an important role in cancer invasion and metastasis. Film in situ zymography (FIZ) enables the in situ evaluation of gelatinolytic activity with high reproducibility. In this article, we report a study of FIZ, in a case of breast cancer with an invasive carcinoma component showing clear gelatinolytic activity, and in a non-invasive carcinoma component showing little gelatinolytic activity. Immunohistochemistry on FIZ was also performed. The simultaneous detection of gelatinolytic activity and immunohistochemical reaction was established in a single film. Immunohistochemistry on FIZ may have good potential for the investigation of cancer microenvironment.

Cytokines in chronic respiratory diseases

Cytokines are small, secreted proteins that control immune responses. Within the lung, they can control host responses to injuries or infection, resulting in clearance of the insult, repair of lung tissue, and return to homeostasis. Problems can arise when this response is over exuberant and/or cytokine production becomes dysregulated. In such cases, chronic and repeated inflammatory reactions and cytokine production can be established, leading to airway remodeling and fibrosis with unintended, maladaptive consequences. In this report, we describe the cytokines and molecular mechanisms behind the pathology observed in three major chronic diseases of the lung: asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. Overlapping mechanisms are presented as potential sites for therapeutic intervention.

Macrophages and fibrosis: How resident and infiltrating mononuclear phagocytes orchestrate all phases of tissue injury and repair

Certain macrophage phenotypes contribute to tissue fibrosis, but why? Tissues host resident mononuclear phagocytes for their support to maintain homeostasis. Upon injury the changing tissue microenvironment alters their phenotype and primes infiltrating monocytes toward pro-inflammatory macrophages. Several mechanisms contribute to their deactivation and macrophage priming toward anti-inflammatory and pro-regenerative macrophages that produce multiple cytokines that display immunosuppressive as well as pro-regeneratory effects, such as IL-10 and TGF-beta1. Insufficient parenchymal repair creates a tissue microenvironment that becomes dominated by multiple growth factors that promote the pro-fibrotic macrophage phenotype that itself produces large amounts of such growth factors that further support fibrogenesis. However, the contribution of resident mononuclear phagocytes to physiological extracellular matrix turnover implies also their fibrolytic effects in the late stage of tissue scaring. Fibrolytic macrophages break down fibrous tissue, but their phenotypic characteristics remain to be described in more detail. Together, macrophages contribute to tissue fibrosis because the changing tissue environments prime them to assist and orchestrate all phases of tissue injury and repair. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Diospyros blancoi attenuates asthmatic effects in a mouse model of airway inflammation

Asthma is a complex disease linked to various pathophysiological events, including proteinase activity. In this study, we examined whether a Diospyros blancoi methanolic extract (DBE) exerts protective effects on allergic asthma in a murine asthma model. To investigate the specific role of DBE, we employed a murine model of allergic airway inflammation. BALB/c mice sensitized and challenged with ovalbumin (OVA) were orally administered 20 or 40 mg/kg DBE for 3 days during OVA challenge. DBE induced significant suppression of the number of OVA-induced total inflammatory cells, including eosinophils, macrophages, and lymphocytes, in bronchoalveolar lavage fluid (BALF). Moreover, treatment with DBE led to significant decreases in interleukin (IL)-4, IL-5, and eotaxin levels in BALF and OVA-specific immunoglobulin (Ig)E and IgG1 levels in serum. Histological examination of lung tissue revealed marked attenuation of allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells in the airway. Additionally, DBE suppressed matrix metalloproteinase-9 activity and induced heme oxygenase-1 expression. The present findings collectively suggest that DBE exhibits anti-inflammatory activity in an airway inflammation mouse model, supporting its therapeutic potential for the treatment of allergic bronchial asthma.

Fra-1/AP-1 transcription factor negatively regulates pulmonary fibrosis in vivo

The Fra-1/AP-1 transcription factor plays a key role in tumor epithelial cell progression; however, its role in pathogenic lung fibrosis remains unclear. In the present study, using a genetic approach (Fra-1 deficient mice), we have demonstrated a novel regulatory (protective) role for Fra-1 in lung fibrosis. We found greater levels of progressive interstitial fibrosis, characterized by increased levels of inflammation, collagen accumulation, and profibrotic and fibrotic gene expression in the lungs of Fra-1^Δ/Δ mice than in those of Fra-1^+/+ mice following bleomycin treatment. Fra-1 knockdown in human lung epithelial cells caused the upregulation of mesenchymal marker N-cadherin, concomitant with a downregulation of the epithelial phenotype marker E-cadherin, under basal conditions and in response to bleomycin and TGF-β1. Furthermore, Fra-1 knockdown caused an enhanced expression of type 1 collagen and the downregulation of collagenase (MMP-1 and MMP-13) gene expression in human lung epithelial cells. Collectively, our findings demonstrate that Fra-1 mediates anti-fibrotic effects in the lung through the modulation of proinflammatory, profibrotic and fibrotic gene expression, and suggests that the Fra-1 transcription factor may be a potential target for pulmonary fibrosis, a progressive disorder with poor prognosis and treatment.

SP-1 regulation of MMP-9 expression requires Ser586 in the PEST domain

Rac1, a small GTPase, regulates macrophage MMP (matrix metalloproteinase)-9 in an ERK (extracellular-signal-regulated kinase)- and SP (specificity protein)-1-dependent manner. SP-1 contains a PEST (Pro-Glu-Ser-Thr) domain that may modulate protein stability. We hypothesize that Thr578, Ser586 and/or Ser587 in the PEST domain are required for SP-1 stability and MMP-9 expression secondary to activation of ERK, a serine/threonine kinase. We determined the effects of Rac1 and ERK on MMP-9 expression driven by SP-1WT (wild-type) and the SP-1 mutants T578A, S586A and S587A. Expression of WT and mutant SP-1 increased MMP9 promoter activity in alveolar macrophages. However, constitutively active Rac1 suppressed MMP9 promoter activity in cells expressing SP-1WT, SP-1T578A and SP-1S587A, but not SP-1S586A. Furthermore, constitutive ERK activation, which was inhibited by Rac1, significantly increased MMP9 transcription in cells expressing SP-1WT, but not SP-1S586A. As Rac1 activation and ERK inactivation increased degradation of SP-1WT and not SP-1S586A, the results of the present study suggest that SP-1 stability mediated at Ser586 regulates MMP9 transcription. Ex vivo, alveolar macrophages obtained from patients with asbestosis had less MMP-9 expression that was associated with decreased SP-1 expression and ERK activation. These observations demonstrate that Ser586 in the PEST domain of SP-1 is important for MMP9 gene expression in alveolar macrophages and highlight the importance of these proteins in pulmonary fibrosis.

Bone marrow-derived matrix metalloproteinase-9 is associated with fibrous adhesion formation after murine flexor tendon injury

The pathogenesis of adhesions following primary tendon repair is poorly understood, but is thought to involve dysregulation of matrix metalloproteinases (Mmps). We have previously demonstrated that Mmp9 gene expression is increased during the inflammatory phase following murine flexor digitorum (FDL) tendon repair in association with increased adhesions. To further investigate the role of Mmp9, the cellular, molecular, and biomechanical features of healing were examined in WT and Mmp9^−/− mice using the FDL tendon repair model. Adhesions persisted in WT, but were reduced in Mmp9^−/− mice by 21 days without any decrease in strength. Deletion of Mmp9 resulted in accelerated expression of neo-tendon associated genes, Gdf5 and Smad8, and delayed expression of collagen I and collagen III. Furthermore, WT bone marrow cells (GFP⁺) migrated specifically to the tendon repair site. Transplanting myeloablated Mmp9^−/− mice with WT marrow cells resulted in greater adhesions than observed in Mmp9^−/− mice and similar to those seen in WT mice. These studies show that Mmp9 is primarily derived from bone marrow cells that migrate to the repair site, and mediates adhesion formation in injured tendons. Mmp9 is a potential target to limit adhesion formation in tendon healing.

New insights into the role of oxidative stress in scleroderma fibrosis

Systemic sclerosis (Scleroderma – SSc) is a connective tissue disorder of unknown aetiology characterized by extensive fibrosis of the skin and visceral organs, by vascular abnormalities and immunological manifestations.

Recent evidence suggest that the cellular redox state may play a significant role in the progression of scleroderma fibrosis. Mechanisms involved include an autoamplification circuit linking ROS, Ras and ERK 1-2 which in turn amplifies and maintains the autocrine loop made up by cytokines, growth factors and their cognate receptors.

This review summarizes the recent progress on the role of oxidative stress in the pathophysiology of scleroderma and disorders characterised by organ fibrosis

Cytokine-like factor 1 gene expression is enriched in idiopathic pulmonary fibrosis and drives the accumulation of CD4+ T cells in murine lungs: evidence for an antifibrotic role in bleomycin injury

Idiopathic pulmonary fibrosis (IPF) is a progressive and typically fatal lung disease. To gain insight into the pathogenesis of IPF, we reanalyzed our previously published gene expression data profiling IPF lungs. Cytokine receptor-like factor 1 (CRLF1) was among the most highly up-regulated genes in IPF lungs, compared with normal controls. The protein product (CLF-1) and its partner, cardiotrophin-like cytokine (CLC), function as members of the interleukin 6 (IL-6) family of cytokines. Because of earlier work implicating IL-6 family members in IPF pathogenesis, we tested whether CLF-1 expression contributes to inflammation in experimental pulmonary fibrosis. In IPF, we detected CLF-1 expression in both type II alveolar epithelial cells and macrophages. We found that the receptor for CLF-1/CLC signaling, ciliary neurotrophic factor receptor (CNTFR), was expressed only in type II alveolar epithelial cells. Administration of CLF-1/CLC to both uninjured and bleomycin-injured mice led to the pulmonary accumulation of CD4(+) T cells. We also found that CLF-1/CLC administration increased inflammation but decreased pulmonary fibrosis. CLF-1/CLC leads to significantly enriched expression of T-cell-derived chemokines and cytokines, including the antifibrotic cytokine interferon-γ. We propose that, in IPF, CLF-1 is a selective stimulus of type II alveolar epithelial cells and may potentially drive an antifibrotic response by augmenting both T-helper-1-driven and T-regulatory-cell-driven inflammatory responses in the lung.